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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer network, and more particularly, to a network-device management apparatus and method relating to a network-device management program for controlling network devices connected to a computer network. 2. Description of the Related Art Today, computers are often interconnected via a local area network (LAN). The local area network is constructed in a floor or the entirety of a building, a group of buildings (an enclosure), a local area, or a larger area. It is also possible to interconnect such networks, and connect the networks to a worldwide network. Each of such interconnected LANs has, in some cases, various hardware interconnecting techniques and a plurality of network protocols. In a simple LAN isolated from other LANs, each user can exchange an apparatus, install software, or examine problems. On the other hand, in a large-scale complicated LAN or a large group of interconnected LANs, “management” is required. The word “management” indicates management by both a network device manager (a human being), and software used by that manager. In the present invention, the word “management” indicates management by software (a network-device management program) for managing the entire system, and the word “user” indicates a human being who uses the network-device management program. Usually, the user is a network-device manager or a person responsible for system management. By using a network-device management program, the user can obtain management data from each network device and change the management data. Usually, a large-scale network system is a dynamic system in which addition or removal of an apparatus, updating of software, detection of problems, and the like are incessantly performed. A description will now be provided of a large-scale network which requires “management”. FIG. 1 is a diagram illustrating a large-scale network. Usually, a printer 102 having an open architecture is connected to a network via a network board (NB) 101 . The NB 101 is connected to a LAN 100 via a LAN interface, such as an Ethernet interface 10Base-2 having a coaxial connector, or 10Base-T having RJ-45, or the like. A plurality of personal computers (PCs), such as a PC 103 , a PC 104 and the like, are also connected to the LAN 100 . These PC 103 , PC 204 and the like can communicate with the NB 101 under the control of a network operating device. The user can use the PC 103 as a PC for managing network devices. A local printer 105 is connected to the PC 104 . Similarly, a local printer, such as the printer 105 or the like, may be connected to the PC 103 , although such is not shown in FIG. 1 . A file server 106 is also connected to the LAN 100 . The file server 106 manages access to a file stored in a large-capacity (for example, ten billion bytes) network disk 107 . A print server 108 manages printing requests to a plurality of printers 109 , the printer 105 installed at a remote location, and the like. Any other peripheral apparatus (not shown) may also be connected to the LAN 100 . A WWW (world wide web) server 150 is also connected to the LAN 100 . The WWW server 150 transmits an HTML (Hyper Text Markup Language) document generated by an installed network-device management program to the PC 103 , which can display the HTML document on a display by means of an installed WWW browser. Alternatively, when the user performs setting of a printer using the WWW browser in the PC 103 , the PC 103 can transmit the contents of the setting to a specific printer via the network-device management program of the WWW server 150 . More specifically, in the network shown in FIG. 1 , in order to perform efficient communication between various network members, network software, such as Novell®, NetWare®, UNIX® or the like, may be used. Although any network software may be used, NetWare (a registered trademark of the Novell Corporation; hereinafter omitted) software is an example of software that is fully suited for this use. For more detailed description relating to this software package, refer to the on-line documentation enclosed in the NetWare package). This documentation can be purchased from the Novell Corporation together with the NetWare package. FIG. 1 will now be briefly described. The file server 106 operates as a file management unit, and performs reception, storage, queuing, caching, and transmission of files. For example, data files formed by each of the PC 103 and PC 104 are transmitted to the file server 106 . The file server 106 sequentially arranges these data files and performs queuing, and sequentially transmits the data files to a printer 109 in accordance with a command from the print server 108 . Each of the PC 103 and PC 104 is an ordinary PC which can perform generation of a data file, transmission of the generated data file to the LAN 100 , reception of files from the LAN 100 , and display and/or processing of the received files. Although only PCs are illustrated in FIG. 1 , any other computers which are suitable for executing network software may also be connected to the network. For example, when UNIX software is used, UNIX workstations may be connected to the network. Such workstations may be used together with the illustrated PCs in an appropriate situation. Usually, the LAN provides a relatively local user group, for example, a user group on a single floor or on a plurality of consecutive floors within a building with service. As the distance between users increases, for example, when users are located in different buildings or prefectures, a wide-area network (WAN) may be constructed. A WAN is basically an aggregate of LANs formed by interconnecting various LANs with a high-speed digital network, such as ISDN (Integrated Services Digital Network) or the like. Accordingly, as shown in FIG. 1 , a WAN is formed by interconnecting the LAN 100 , a LAN 110 and a LAN 120 via modem/transponders 130 , 130 b and a backbone 140 . Dedicated PCs, and if necessary, a file server and a print server, are connected to each of the LANs. As shown in FIG. 1 , a PC 111 , a PC 112 , a file server 113 , a network disk 114 , a print server 115 and a number of printers 116 are connected to the LAN 110 . On the other hand, only a PC 121 and a PC 122 are connected to the LAN 120 . The devices connected to the LAN 100 , the LAN 110 and the LAN 120 can access the functions of apparatuses connected to other LANs via the WAN connection. In order to manage devices connected to networks constituting such a large-scale network system, various attempts have been made by a large number of standardization organizations. The International Organization for Standardization (ISO) has provided a general-purpose standard framework called an Open System Interconnection (OSI) model. The OSI model of a network-device control protocol is called a Common Management Information Protocol (CMIP). The CMIP is a network-device control protocol common in Europe. Recently, a modification of the CMIP, called a Simple Network Management Protocol (SNMP), has been used as a network-device management protocol capable of being more commonly used (see the first edition, Aug. 20, 1992, of “Introduction to TCP/IP Network-Device Management: Aiming at Practical Management” written by M. T. Rose, translated by Takeshi Nishida, published by Toppan Printing Company, Limited). A network-device management system according to this SNMP network-device management technique includes at least one network-device management station (NMS), a plurality of nodes to be managed, each including an agent, and a network-device management protocol to be used by the network-device management station and the agent for exchanging management information. Usually, the user can obtain data on the network or change the data by communicating with agent software on a node to be managed using a network-device management program in the NMS. The word “agent” indicates software running at each node to be managed as a background process. When the user requests management data to a device on the network, the network-device management program puts object identifying information in a management packet or frame, and transmits the packet or frame to the agent of the device. The agent interprets the object identifying information, puts data corresponding to the object identifying information in a packet, and transmits the packet to the network-device management program. The agent calls, in some cases, a corresponding process in order to extract data. The agent holds management data relating to the state of the device in the form of a database. This database is called an MIB (management information base). The MIB has the data structure of a tree, in which all nodes are uniquely numbered. An identifier for each of the nodes is called an object identifier. The structure of the MIB is called a Structure of Management Information (SMI), which is provided in “RFC1155 Structure and Identification of Management Information for TCP/IP-Based Internets”. In this specification, management data for a network device is equivalent to information allocated to the MIB object identifier (MIB information). Next, the SNMP will be briefly described. Communication is performed between a PC (manager) where the network-device management program operates and a network device (agent) to be managed where an SNMP agent operates using the SNMP. The SNMP has five types of commands, i.e., Get-request, Get-next-request, Get-response, Set-request, and Trap. Get-request and Get-next-request commands are commands to be transmitted from the manager to the agent in order for the manager to acquire the value of the MIB object (MIB information) of the agent. The agent which has received this command transmits a Get-response command in order to notify the manager of the value of the MIB object. A Set-request command is a command transmitted from the manager to the agent in order for the manager to set the value of the MIB object of the agent. The agent which has received this command sets the value of the MIB object, and transmits a Get-response command to the manager in order to notify the manager of the result of the setting. A Trap command is a command transmitted from the agent to the manager in order to notify the manager of a change in the state of the agent's own device. A system is well known in which the SNMP agent operates in the printer itself or the network board (NB 101 ) connected to the printer, and the network-device management program, serving as the SNMP manager, operates in the PC. SUMMARY OF THE INVENTION In accordance with recent spread of use of the Internet, a system has been proposed in which a dedicated network-device management program operates in a server, and a WWW browser is used as a user interface. An outline of the operation of an ordinary WWW system and the operation of an SNMP management program based on the WWW system will now be described with reference to FIG. 2 . In FIG. 2 , a WWW server program 1501 operates in a PC 150 . A large number of WWW page data (WWW documents or templates for generating respective WWW documents) described using the HTML are stored on a hard disk of the PC 150 . In order to display a page assigned by the user, a WWW browser program 1031 requests the WWW server program 1501 operating in the PC 150 to acquire page data of the assigned page. The WWW server program 1501 transmits the assigned page data in response to the request from the WWW browser program 1031 . The WWW browser program 1031 analyzes the acquired page data and displays the page based on the description. When a request using a CGI (Common Gateway Interface) is included within the request to acquire the page data from the WWW browser program 1031 , the WWW server program 1501 starts an external script or program using the CGI. The WWW server program 1501 then acquires page data generated by the external script or program, and transmits the acquired data to the WWW browser program 1031 . Next, a description will be provided of a case in which the external program started by the CGI is a network-device management program. A network-device management program 1502 started by the WWW server program 1501 using the CGI acquires management data from a device connected to the network, for example, a printer 102 , using the SNMP. The network-device management program 1502 generates page data described by the HTML (hereinafter termed an “HTML document”) based on the acquired management data, and transmits the generated data to the WWW server program 1501 . FIGS. 9 and 10 illustrate examples of display of HTML documents generated by the network-device management program 1502 . FIG. 9 is an example of display of a device list in which a summary of network devices connected to the network is displayed. In this example, MIB information, including the device name, the product name, the network interface board name, the network address and the state, is acquired from each network device connected to the network, and the acquired information is displayed. FIG. 10 is an example of display of the details of each device performed when the user has selected a specific device in the display shown in FIG. 9 , in order to display further details of the selected device. In the case of FIG. 10 , the state of the network device (printer), the status of mounting of optional devices, the states of sheet feeding and discharging units, and the like are acquired as MIB information, and display is performed based on the acquired MIB information. If the network-device management program 1502 utilizing the WWW system acquires management data from a network device every time a request to display MIB information is provided from the WWW browser program 1031 , too much time is required from the request of display to display of management data. Accordingly, the network-device managment program 1502 preserves management data acquired from a device to be managed in a memory (RAM (random access memory)) or a hard disk (HD) in a local PC (a device storing data, such as a RAM, a HD or the like, will be hereinafter termed a “cache”, and data stored therein will be hereinafter termed a “cache file”). Instead of newly acquiring management data from a device to be managed, the network-device management program 1502 generates an HTML document using management data preserved in the cache for a specific period from the acquisition of the management data. In this approach, a problem arises in that the user cannot know when management data displayed on the WWW browser as shown in FIG. 9 or 10 which has been acquired from a network device by the network-device management program that uses the cache was acquired from the network device. For example, even if management data obtained by the user by starting the WWW browser is management data which has been just displayed on the WWW browser via the network-device management program of the WWW server (the user feels as if the displayed data is information newly acquired from the network device), there is the possibility that the displayed data is actually old management data acquired from the network device by the network-device control program a few hours before, based on a request from another WWW browser. To the contrary, even if information displayed on the WWW browser is information just now acquired from the network device by the network-device management program based on a request from the WWW browser, the user cannot know if the management data in the network device coincides with the management data displayed on the WWW browser (i.e., if the very latest information is displayed). Accordingly, there arises a problem in that the user may unnecessarily provide a command to “update to latest information” (the user can instruct the network-device management program to generate an HTML document by newly acquiring management data by depressing a button 903 shown in FIG. 9 or a button 1003 shown in FIG. 10 , instead of merely reaquiring the HTML document), thereby increasing the load on the network-device management program operating in the WWW server beyond what is necessary. It is an object of the present invention to provide a network-device management apparatus and method using a cache represented by a network-device management program in a WWW system or the like, in which the above-described problems are solved. According to one aspect of the present invention, a network-device management method for managing network devices connected to a network includes an acquisition step, of acquiring device information relating to a network device, a time acquisition step, of acquiring time data substantially indicating a time of acquisition of the device information, and a conversion step, of converting the device information and the time data into a form conforming to a predetermined display format. According to another aspect of the present invention, in a method for controlling a network-device management system including a network-device management apparatus for managing network devices connected to a network, and an information processing apparatus capable of displaying device information relating to a network device managed by the network-device management apparatus, a method for controlling the network-device management apparatus includes a reception step, of receiving a command from the information processing apparatus, an acquisition step of acquiring the device information, a time acquisition step, of acquiring time data substantially indicating a time of acquisition of the device information, a conversion step, of converting the device information and the time data into a form conforming to a predetermined display format, and a transmission step, of transmitting the device information and the time data to the image processing apparatus in the form after being converted in the conversion step. A method for controlling the image processing apparatus includes a command transmission step of transmitting the command to the network-device management apparatus, and an information reception step, of receiving the device information and the time data in the converted form. According to still another aspect of the present invention, a network-device management apparatus for managing network devices connected to a network includes acquisition means for acquiring device information relating to a network device, time acquisition means for acquiring time data substantially indicating a time of acquisition of the device information, and conversion means for converting the device information and the time data into a form conforming to a predetermined display format. According to yet another aspect of the present invention, in a network-device management system including a network-device management apparatus for managing network devices connected to a network, and an information processing apparatus capable of displaying device information relating to a network device managed by the network-device management apparatus, the network-device management apparatus includes reception means for receiving a command from the information processing apparatus, acquisition means for acquiring the device information, time acquisition means for acquiring time data substantially indicating a time of acquisition of the device information, conversion means for converting the device information and the time data into a form conforming to a predetermined display format, and transmission means for transmitting the device information and the time data to the image processing apparatus in the form after being converted by the conversion means. The image processing apparatus includes command transmission means for transmitting the command to the network-device management apparatus, and information reception means for receiving the device information and the time data in the form after being converted. According to yet a further aspect of the present invention, in a recording medium storing a network-device management program for managing network devices connected to a network, the network-device management program includes an acquisition step, of acquiring device information relating to a network device, a time acquisition step, of acquiring time data substantially indicating a time of acquisition of the device information, and a conversion step, of converting the device information and the time data into a form conforming to a predetermined display format. According to still another aspect of the present invention, in a recording medium storing programs for a network-device management system including a network-device management apparatus for managing network devices connected to a network, and an information processing apparatus capable of displaying device information relating to a network device managed by the network-device management apparatus, a program in the network-device management apparatus includes a reception step, of receiving a command from the information processing apparatus, an acquisition step, of acquiring the device information, a time acquisition step, of acquiring time data substantially indicating a time of acquisition of the device information, a conversion step, of converting the device information and the time data into a form conforming to a predetermined display format, and a transmission step, of transmitting the device information and the time data to the image processing apparatus in the form after being converted in the conversion step. A program in the image processing apparatus includes a command transmission step, of transmitting the command to the network-device management apparatus, and an information reception step, of receiving the device information and the time data in the converted form. According to still another aspect of the present invention, in a transmission apparatus for transmitting a network-device management program for managing network devices connected to a network, the network-device management program includes an acquisition step, of acquiring device information relating to a network device, a time acquisition step, of acquiring time data substantially indicating a time of acquisition of the device information, and a conversion step, of converting the device information and the time data into a form conforming to a predetermined display format. According to still another aspect of the present invention, in a transmission apparatus for transmitting programs for a network-device management system including a network-device management apparatus for managing network devices connected to a network, and an information processing apparatus capable of displaying device information relating to a network device managed by the network-device management apparatus, a program in the network-device management apparatus includes a reception step of receiving a command from the information processing apparatus, an acquisition step, of acquiring the device information, a time acquisition step, of acquiring time data substantially indicating a time of acquisition of the device information, a conversion step, of converting the device information and the time data into a form conforming to a predetermined display format, and a transmission step, of transmitting the device information and the time data to the image processing apparatus in the form after being converted in the conversion step. A program in the image processing apparatus includes a command transmission step of transmitting the command to the network-device management apparatus, and an information reception step, of receiving the device information and the time data in the converted form. The foregoing and other objects, advantages and features of the present invention will become more apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating the configuration of a LAN; FIG. 2 is a block diagram illustrating an outline of the operation of an ordinary WWW system and the operation of a network-device management program based on the WWW system; FIG. 3 is a block diagram illustrating the configuration of a PC, in which a network-device management program can operate, according to an embodiment of the present invention; FIG. 4 is a block diagram illustrating the configuration of each module of a network-device management program according to that embodiment; FIG. 5 is a flowchart illustrating processing of acquiring management data from a network device in that embodiment; FIG. 6 is a flowchart for a case in which management data is preserved in a form before being converted into information for display when generating the information for display in response to a request from a client, in that embodiment; FIG. 7 is a flowchart when management data is preserved in a form after being converted into information for display in that embodiment; FIG. 8 is a flowchart when the form of preserving management data can be changed according to information for display in that embodiment; FIG. 9 is a diagram illustrating an example of display of a device list in which a summary of network devices to be managed that are connected to a network is displayed; FIG. 10 is a diagram illustrating an example of display of the details of a network device, in which further detailed information of the device is displayed; FIG. 11 is a diagram illustrating an example of display of a device list generated by a network-device management program in the embodiment of FIG. 3 ; FIG. 12 is a diagram illustrating an example of display of the details of a device generated by the network-device management program in that embodiment; FIG. 13 is a diagram illustrating an image of a memory map of a storage medium storing the network-device management program in that embodiment; and FIG. 14 is a diagram illustrating a storage medium storing program codes, and a transmission apparatus for transmitting the program codes. DESCRIPTION OF THE PREFERRED EMBODIMENT A network-device management method according to an embodiment of the present invention will now be described. Particularly, a description will be provided of a network-device management method using a WWW system with reference to the drawings. A network-device management method or apparatus according to the present invention is realized by PCs having the same configuration as PCs which can realize a conventional network-device management apparatus, as shown in FIG. 3 . In FIG. 3 , a network-device management program operates in a PC 150 , which is equivalent to the PC 150 shown in FIG. 1 . A CPU (central processing unit) 301 executes a network-device management program stored in a storage medium, such as a ROM (read-only memory) 302 , a hard disk (HD) 311 , a floppy disk (FD) 312 or the like, and controls respective devices connected to a system bus 304 . A RAM 303 operates as a main memory, a working area or the like for the CPU 301 . A keyboard controller (KBC) 305 controls input from a keyboard (KB) 309 or a pointing device (not shown). A CRT (cathode-ray tube) controller (CRTC) 306 controls display on a CRT display (CRT) 310 . A disk controller (DKC) controls access to the hard disk (HD) 311 and the floppy disk (FD) 312 storing boot programs, various application programs, editing files, user files, the network-device management program and the like. A network interface card (NIC) 308 performs two-way data exchange with an agent or a network device via a LAN 100 . In the following description, unless otherwise mentioned, the subject of execution in hardware is the CPU 3012 , and the subject of execution in software is the network-device management program stored in the hard disk (HD) 311 . In FIG. 1 , a combination, for example, of the network board (NB) 101 connected to the network and the printer 102 where the network board 101 is mounted is termed a network device. FIG. 4 is a diagram illustrating the configuration of each module of a network-device management program 1502 of the embodiment. The network-device management program 1502 of the embodiment is stored in the HD 311 shown in FIG. 3 , and is executed by the CPU 301 . At that time, the CPU 301 uses the RAM 303 as a working area. In FIG. 4 , the network-device management program 1502 is started from a WWW server program 1501 , and exchanges CGI parameters and HTML documents with the WWW server program 1501 via a CGI (common gateway interface) 402 . An overall control module 403 registers a CGI parameter for a parameter module (to be described later), and then allocates control to one of a system module 405 , a device-list module 407 and a device-detail module 409 (to be described later) in accordance with a command parameter within the CGI parameter. If there is an error in the CGI parameter, the overall control module 403 generates, in some cases, an HTML document indicating the presence of error in the CGI parameter via a template module 412 (to be described later). A parameter module 404 preserves/manages CGI parameters registered by the overall control module 403 in the form of a table. Any other module can acquire a desired parameter from the parameter module 404 whenever necessary. The system module 405 controls display/setting of system parameters for defining the operation of the network-device management program 1502 (such as the interval of automatic updating of an HTML document, and the like), and generates a related HTML document via the template module 412 . The system module 405 acquires a command parameter from the parameter module 404 . When the contents of the acquired command parameter indicate a request to display a system parameter, the system module 405 reads necessary information from a system setting file 406 , and generates and HTML document for system parameter display via the template module 412 . When the contents of the acquired command parameter indicate a request to set a system parameter, the system module 405 writes the notified system parameter in the system setting file 406 , and generates an HTML document to be displayed after setting via the template module 412 . Although not illustrated in FIG. 4 , a system parameter preserved in the system setting file 406 can be read by each module constituting the network-device management program 1502 , whenever necessary. The device-list module 407 generates an HTML document indicating a summary of devices (device list) retrieved by a device-discovery module 408 (to be described below) via the template module 412 . Processing of optional display of the device list, and the like are also controlled by the device-list module 407 . A device-discovery module 408 discovers a network device connected to the network. The device-detail module 409 performs control for displaying/setting detailed information relating to a specific network device assigned by a CGI parameter, and generates a related HTML document via the template module 412 . In order to acquire/set detailed information relating to the assigned device, the device-detail module 409 uses a device specific module 410 (to be described below) corresponding to the assigned network device. A device specific module 410 is provided for each device (a printer, a network interface board or the like) to be managed by the network-device management program. When displaying device-detail information, the device specific module 410 acquires necessary information from the device, and provides the template module 412 with the acquired information. When setting a setting value for the network device, the device specific module 410 converts the setting value notified in a CGI parameter into a value capable of being interpreted by the network device, and transmits the obtained value to the device. A protocol module 411 performs control of various protocols necessary for the network-device management program to communicate with the network device, such as handling of MIB, transmission/reception of an SNMP packet, control of a transport protocol, and the like. The template module 412 generates an HTML module as a result of output of the network-device management program, based on a template file 413 preserved in the hard disk 311 shown in FIG. 3 . The template module 412 opens a template file assigned by a CGI parameter, the entire control module 403 , the system module 405 , the device-list module 407 or the device-detail module 409 , and analyzes the contents of the template file. The template module 412 also generates an HTML document by replacing a template variable contained in the template file by a value transmitted from the entire control module 403 , the system module 405 , the device-list module 407 , the device-detail module 409 or the device specific module 410 , whenever necessary. The generated HTML document is transmitted to the WWW server program via the CGI interface 402 . The value of the template variable used when generating the HTML document or the generated HTML document file can also be preserved on the hard disk 311 shown in FIG. 3 as a cache file 414 . Thus, processing time when generating an HTML document at the second or later time based on the same template file is shortened. Next, a description will be provided of the processing of the network-device management program when preserving the template variable or the management data used when generating the HTML document on the hard disk 311 as a cache file, with reference to FIGS. 5 and 6 . FIG. 5 is a flowchart illustrating the processing of acquisition of management data from a network device by the network-device management program. In step S 501 , Get-request and Get-next-request commands are transmitted to the concerned network device. By receiving a Get-response command, management data of the network device is acquired via the network. Although not illustrated in FIG. 5 , when a Get-response command expected for the Get-request and Get-next-request commands could not be received, appropriate error recovery processing, for example, retransmission of commands, is, of course, performed. Usually, a network device is assigned in the form of a network address or the like as a CGI parameter. In step S 502 , system-time data (time of acquisition of management data) of the WWW server when the processing of the above-described step S 501 has been completed is acquired. In step S 503 , the management data acquired in the above-described step S 501 and the management-data acquisition time acquired in the above-described step S 502 are preserved as the cache file 414 shown in FIG. 4 . It is assumed that the contents of the cache file 414 are preserved and can be referred to for each type of request from the WWW browser. FIG. 6 is a flowchart illustrating the processing of generating an HTML document for displaying network-device management data in accordance with a request from the WWW browser by the network-device management program of the embodiment. In step S 601 , it is determined if management data corresponding to the request for display (management data necessary for a page requested to be displayed) is present in the cache file. If the result of the determination in step S 601 is affirmative, the process proceeds to step s 602 . If the result of the determination in step S 601 is negative, the process proceeds to step S 603 . In step S 602 , aquisition-time data of management data corresponding to the request for display within the cache file is compared with the system time (the current time) of the WWW server. When the management data is acquired within a specific period before the current time, i.e., relatively new information, the process proceeds to step S 604 . When the management data is not acquired within the specific period, i.e., old information, the process proceeds to step S 603 . The specific period, i.e., an effective period for data preserved in the cache file 414 , may be determined so as to be inherent in the system of the network-device management program, or may be set by the user, for example, according to a system setting page of the network-device management program. In step S 603 , the processing of acquiring information relating to the requested management data shown in FIG. 5 is executed. In step S 604 , the requested management data is read from the cache file 414 . In step S 605 , data relating to the acquisition time of the requested management data in the cache file 414 is read, and the process proceeds to step S 606 . In step S 606 , the management data read in the above-described step S 604 and the acquisition-time data read in the above-described step S 605 are converted into a form capable of being displayed on the WWW browser (for example, an HTML document), and an HTML document is generated and output. In the flowcharts shown in FIGS. 5 and 6 , after newly acquiring the management data and the acquisition-time data in the information acquisition processing, the acquired data is prevserved in the cache, and the preserved data is then read to form an HTML document. However, after generating an HTML document from the newly acquired data (the management data and the acquisition-time data), the acquired data (the management data and the acquisition-time data) may be preserved in the cache. FIG. 7 is a flowchart illustrating the processing of generating an HTML document for displaying network-device management data in response to a request from the WWW browser by the network-device management program, when the generated HTML document is preserved on the hard disk as the cache file 414 . In step S 701 , it is determined if the HTML document for a page requested to be displayed is present in the cache. If the result of the determination in step S 701 is affirmative, the process proceeds to step S 702 . If the result of the determination in step S 701 is negative, the process proceeds to step S 704 . In step S 702 , data relating to the acquisition time of management data for the HTML document within the cache file (data relating to the generation time of the HTML document may be used assuming that the generation time of the HTML document is the acquisition time of the management data) is compared with the system time (the current time) of the WWW server. When the management data is acquired within a specific period before the current time, i.e., is relatively new information, the process proceeds to step S 703 . When the management data is not acquired within the specific period, i.e., old information, the process proceeds to step S 704 . The specific period, i.e., an effective period for data preserved in the cache file 414 , may be determined so as to be inherent in the system of the network-device management program, or may be set by the user, for example, according to a system setting page of the network-device management program. In step S 703 , the HTML document for a page requested to be displayed is read from the cache file and is output. In step S 704 , Get-request and Get-next-request commands are transmitted to the concerned network device, and a Get-response command is received. Then, management data of the network device is acquired via the network. Although not illustrated in FIG. 7 , when a Get-response command expected for the Get-request and Get-next-request commands could not be received, appropriate error recovery processing, for example, retransmission of commands, is, of course, performed. Usually, a network device is assigned in the form of a network address or the like as a CGI parameter. In step S 705 , the system time data (the time of acquisition of the management data) of the WWW server when the processing of the above-described step S 704 has been completed is acquired. In step S 706 , using the management data acquired in the above-described step S 704 and the management-data acquisition time acquired in the above-described step S 705 , an HTML document (in a form capable of being displayed on the WWW browser) is generated and output. In step S 707 , the HTML document generated in the above-described step S 706 is preserved as a cache file, and the processing is terminated. In the above-described description with reference to FIG. 7 , the management-data acquisition time is compared with the current time, and it is determined if the acquired management data is a document within an effective period. However, the management-data acquisition time may be obtained by reading data contained within the HTML document, or a file for managing the time may be formed and used separately from the HTML document. In the flowchart shown in FIG. 7 , after generating and outputting the HTML document in steps S 706 and S 707 , the HTML document is preserved. However, a configuration may, of course, be adopted in which after generating and preserving the HTML document, the HTML document is read and output. When preserving data in the cache, the data is preferably preserved in the form of an HTML document or as the value of a template variable depending on the type of information for display. For example, when it is necessary to frequently change management data within information for display, the data may be preserved as the value of a template variable, and when it is unnecessary to frequently change the management data, the data may be preserved in the form of an HTML document. FIG. 8 is a flowchart in which either one of the processing shown in FIGS. 5 and 6 and the processing shown in FIG. 7 is selected depending on information to be displayed. In step S 801 , it is determined if information for display (an HTML document is a type of information for display) requested to be displayed is to be preserved in the form of an HTML document in the cache. If the result of the determination in step S 801 is affirmative, the process proceeds to step S 802 . If the result of the determination in step S 801 is negative, the process proceeds to step S 803 . In step S 802 , the display requesting processing shown in FIG. 7 is executed, and the process is then terminated. In step S 803 , the display requesting processing shown in FIGS. 5 and 6 is executed, and the process is then terminated. Although a description has been provided with reference to the flowcharts shown in FIGS. 5 through 8 , any other time may be used as the acquisition-time data, provided that the used time can be dealt with as a time substantially the same as the time of acquisition of management data. For example, when management data is acquired and immediately preserved as in the case of FIG. 5 , the time of preservation may be dealt with as the time of acquisition without causing any problem. When management data is acquired and information for display is immediately generated and preserved as in the case of FIG. 7 , the time of preservation of the information for display may be dealt with as the time of acquisition without causing any problem. Acquisition-time data may be acquired/preserved for a plurality of management data (a group of management data) within information for display (for example, an HTML document), for each management data within information for display, or for each information for display. When determining whether or not management data or information for display preserved in the cache is old, acquisition-time data preserved in order to be used for information for display may be used. Alternatively, time data which can be substantially dealt with as the acquisition time may be preserved as different data to be used for the determination. In the aboved-described embodiment, generated/preserved information for display may be in the form of an HTML documentation, or in any other form capable of being displayed on the WWW browser (an HTML format, a text format, an image format or the like). In the preferred embodiment, it is assumed that the network-device management program is operated on the WWW server and information for display is displayed on the WWW browser. However, the present invention may, of course, be used in order that a network-device management program in a server/client system other than the WWW system, a network-device management program using a cache, or the like notifies the user of when managment data displayed on a display picture surface has been acquired. In the above-described embodiment, in order to indicate whether or not management data preserved in a cache module within a network-device management program is old, time data is displayed in information for display. However, when the network-device management program side does not have a cache, and a display program (such as a WWW browser or the like) at the client side has a mechanism for preserving information for display, time data may be substantially contained in information for display in order to indicate when management data contained in information for display has been acquired. In this case, also, as in the above-described embodiment, it is possible to prevent the user from executing an unnecessary “update to latest information” command, reduce the load of the network device or the network-device management program, and reduce traffic in the network. FIG. 11 illustrates an example of display of a device list generated by the network-device management program in this embodiment. FIG. 12 illustrates an example of display of device details generated by the network-device management program in this embodiment. In FIG. 11 , reference numeral 1105 represents the time of acquisition of management data from each network device subjected to summary display by the network-device management program. In FIG. 12 , reference numeral 1204 represents the time of acquisition of detailed information of management data from the concerned network device by the network-device management program. The user can confirm how new displayed management data is by confirming the displayed time. The user can also execute a command for updating information to the latest information whenever necessary (by depressing a button 1103 or 1203 ). The network-device management program of the embodiment may also be executed by a PC having a configuration equivalent to the configuration of the PC 150 shown in FIG. 5 according to a program installed from the outside. In such a case, the objects of the present invention may, of course, be achieved by supplying a system or an apparatus with a storage medium, such as a storage medium 1402 shown in FIG. 14 , storing program codes of software for realizing the functions of the above-described embodiment, and reading and executing the program codes stored in the storage medium by means of a computer (or a CPU or an MPU (microprocessor unit)) of the system or the apparatus. In such a case, the program codes themselves read from the storage medium realize the functions of the above-described embodiment, so that the storage medium storing the program codes constitutes the present invention. For example, a magnetic disk, such as a floppy disk, a hard disk or the like, an optical disk, a magnetooptical disk, a CD(compact disc)-ROM, a CD-R (recordable), a DVD(digital versatile disc)-ROM, a DVD-RAM, a magnetic tape, a memory card, a ROM or the like may be used as the storage medium for supplying the program codes. The present invention may, of course, be applied to a case in which a program is distributed from storage medium storing program codes of software for realizing the functions of the above-described embodiment via a communication line for PC communication or the like. FIG. 13 is a diagram illustrating a memory map of a storage medium, such as a CD-ROM or the like. In FIG. 13 , a region 1301 stores directory information which indicates the positions of a region 1302 storing an install program and a region storing a network-device management program 1303 . When the network-device management program of the embodiment is installed in a PC equivalent to the PC 150 shown in FIG. 3 , first, the install program stored in the region 1302 is loaded into the PC, and is executed by the CPU 301 . Then, the install program executed by the CPU 301 reads the network-device management program from the region 1303 storing the network-device management program, and stores the read program onto the hard disk 311 . When the present invention is applied to the above-described storage medium, program codes corresponding to the above-described flowcharts are stored in the storage medium. Briefly speaking, each module as that shown in the example of the module configuration of FIG. 4 is stored in the storage medium. The objects of the present invention may, of course, be applied to a case in which, as shown in FIG. 14 , a transmission apparatus 1404 , such as an HTTP (Hyper Text Transfer Protocol) server, an FTP (File Transfer Protocol) server or the like, transmits program codes of software for realizing the various functions of the above-described embodiment, a computer (or a CPU or an MPU) of the system or the apparatus receives the transmitted program codes via a network, a public network, radio transmission or the like represented by reference numeral 1405 , the computer executes the program codes. In such a case, the program codes themselves transmitted from the transmission apparatus realize the functions of the above-described embodiment, so that the transmission apparatus for ttransmitting the program codes constitutes the present invention. The present invention may be applied to a system or a composite apparatus comprising a plurality of apparatuses (such as a host computer, an interface apparatus, a reader and the like) or to an apparatus comprising a single unit. The present invention may be applied not only to a case in which the functions of the above-described embodiment are realized by executing program codes read by a computer, but also to a case in which an OS (operating system) or the like operating in a computer executes a part or the entirety of actual processing, and the functions of the above-described embodiment are realized by the processing. The present invention may also be applied to a case in which, after writing program codes read from a storage medium into a memory provided in a function expanding board inserted in a computer or in a function expanding unit connected to the computer, a CPU or the like provided in the function expanding board or the function expanding unit performs a part or the entirety of actual processing, and the functions of the above-described embodiment are realized by the processing. As described above, accoring to the present invention, it is possible to display time data substantially indicating the time of acquisition of device information in information for display for displaying the device information (management data). According to an instruction from the client side (user side), the information for display can be displayed at the client side. By allowing preservation of device information, it is possible to reduce the number of acquisition of device information. It is also possible to preserve device information in a form before conversion into information for display or in a form after conversion into information for display, so as to be convenient for processing. By allowing automatic change of the form of preservation depending on the type of device information, the efficiency in display processing can be improved. By automatically determining whether or not preserved device information is old, it is possible to display device information acquired within a predetermined period. In the determination, by preserving time data to be used as a criterion for the determination separately from the acquired time data, it is possible to efficiently perform the determination. If the determination is performed based on the above-described acquisition-time data without preserving time data as a criterion for the determination, it is possible to reduce the capacity of a memory for preserving the data. Since the substantial time of acquisition of device information may be used as the acquisition time if there is little differece between the two types of times, time acquisition processing can be appropriately performed. By generating and transmitting information for display when a command from a client has been received, it is possible to reduce the load of the management program and the network device. By peforming transmission/reception with the client via the WWW server program, the client side need not newly introduce a program for displaying device information if an existent WWW browser has been introduced. By thus indicating the time of acquisition of device information from a network device, it is possible to reduce the number of operations of transmitting a command to cause the network-device management program to acquire device information from a client (user), and efficiently preserve management data. Hence, it is possible to reduce the load on the network traffic and the network-device management program, the load on the network device, and the like. The individual components shown in outline or designated by blocks in the drawings are all well known in the network-device management apparatus and method, recording medium, and transmission apparatus arts and their specific construction and operation are not critical to the operation or the best mode for carrying out the invention. While the present invention has been desribed with respect to what is presently considered to be the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment. To the contrary, the present invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretations so as to encompass all such modifications and equivalent structures and functions.

In a management system for managing network devices connected to a network, it is considered to reduce the load of the network and the devices by preserving device information acquired from each device and not acquiring new information from the device for a predetermined period. However, this approach has a problem in that the user cannot know when the displayed information was acquired. In the present invention, when preserving device information, the time of acquisition of the device information is preserved as acquisition-time data, which is displayed within displayed information together with the device information. The above-described probem is thereby solved, and the user can acquire very reliable information.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an electrical connector and an electrical connector assembly, more particularly to an electrical connector and an electrical connector assembly for power transmission. [0003] 2. Description of Related Art [0004] Electrical connectors are widely used today. In general, electrical connectors can be classified into personal use and industrial use. When in personal use, electrical connectors can be classified as desktop connectors, laptop connectors, mobile phone connectors, consuming connectors, and other types. When in industrial use, electrical connectors can be used in industrial computers, servers, and workstations. Power connector is one common kind of electrical connector used in different equipments. Usually, a plug-type power connector and a receptacle-type power connector mate with each other to supply power to the equipments. Contacts of the plug connector and the receptacle connector contact one another to form electrical connection. [0005] China Patent No. CN200820212432.9 disclosed a plug connector and a receptacle connector mating with each other for power transmission. The plug connector comprises a plug insulative housing and a plurality of plug contacts received in the plug insulative housing for power transmission. The plug insulative housing defines a receiving cavity for receiving the receptacle connector. The plug contact is of slice structure and extends into the receiving cavity for electrically connecting with the receptacle connector. Since the slice-shape plug contacts are exposed into the receiving cavity directly without any protection to contacting ends thereof, the contacting ends are prone to be contacted when in improper use status. Therefore, electric shock phenomenon has great possibility to be generated and the contacting ends are easy to be polluted or damaged. It is more serious when the connectors are used for high-power, high-voltage situations. [0006] Europe Patent No. EP1703597A1 disclosed a power connector comprising an insulative housing and a plurality of contacts assembled in the insulative housing. A one-piece retainer is assembled to the insulative housing and has protecting sections partially covering the front ends of contacting portions and upper and lower surfaces of the contacts. The retainer protects the contacting portions of the contacts from being touched unintendedly. Also, the protected contacting portions of the contacts also can avoid arc-discharge generation which is capable of influencing safe power transmission. The patent assures the contacts not to be touched from outside and also assures that the contacts not to be polluted or damaged for safe power transmission. However, the retainer is of one-piece structure and needs to align with all the contacting portions of the contacts before assembled to the insulative housing which adds the difficulty of assembly. Further, the contacting portions of the contacts are only partially covered by the retainer. The uncovered parts of the contacting portions of the contacts are still very close to the outside and easy to be polluted or damaged. Also, the one-piece structure has relative slim figure and insufficient strength which is not good enough. Further, when one contact is out of use, the whole retainer needs to be removed for repair which is not convenient enough. [0007] Hence, it is disable to design an electrical connector and an electrical connector assembly to address problems mentioned above. BRIEF SUMMARY OF THE INVENTION [0008] Accordingly, an object of the present invention is to provide an electrical connector with improved protection means for providing reliable power transmission. [0009] Another object of the present invention is to provide an electrical connector assembly with improved protection means for providing reliable power transmission. [0010] In order to achieve the above-mentioned object, an electrical connector comprises an insulative housing, at least one contact and at least one protecting insulator. The insulative housing defines a mating direction, a mating face and a receiving cavity recessed from the mating face along said mating direction. The at least one contact is received in the insulative housing and comprises a contacting portion exposed into the receiving cavity, a retaining portion extending from one end of the contacting portion to be interferentially received in insulative housing, a forward end extending from the other end of the contacting portion to locate more closely to the mating face of the insulative housing than the contacting portion, and a connecting portion extending from the retaining portion to be exposed beyond the insulative housing. The protecting insulator entirely covers the forward end of the at least one contact. [0011] In order to achieve the above-mentioned object, an electrical connector assembly comprises a plug connector and a receptacle connector mating with the plug connector. The plug connector comprises a first insulative housing defining a mating face and a receiving cavity recessed along a mating direction from the mating face, at leas one first contact received in the first insulative housing, and at least one protecting insulator. The at least one first contact comprises a first contacting portion exposed in the receiving cavity, a first retaining portion extending from one end of the first contacting portion and retained in the first insulative housing, a forward end extending from the other end of the first contacting portion to be closer to the mating face than the first contacting portion. The at least one protecting insulator entirely covers the forward end of the at least one contact. The receptacle connector comprises a second insulative housing, and at least one second contact received in the second insulative housing. The at least one second contact comprises an elastic second contacting portion electrically connecting with the at least one first contact. The second insulative housing is received in the receiving cavity of the first insulative housing, and the elastic second contacting portion of the at least second contact slides along the protecting insulator then forms electrical connection with the first contacting portion of the at least one first contact. [0012] The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter, which form the subject of the claims of the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0013] For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: [0014] FIG. 1 is an assembled, perspective view of an electrical connector assembly in accordance with the first embodiment of the present invention, wherein a plug connector (electrical connector) and a receptacle connector (electrical connector) of the electrical connector assembly are in mating status; [0015] FIG. 2 is a view similar to FIG. 1 , but viewed from a different aspect; [0016] FIG. 3 is a perspective view of the electrical connector assembly with the plug connector and the receptacle connector in separate status; [0017] FIG. 4 is a view similar to FIG. 3 , but viewed from a different aspect; [0018] FIG. 5 is an exploded, perspective view of the plug connector in accordance with the first embodiment of the present invention; [0019] FIG. 6 is an exploded, perspective view of a first contact and a protecting insulator of the plug connector; [0020] FIG. 7 is an exploded, perspective view of the receptacle connector (electrical connector) in accordance with a first embodiment of the present invention; [0021] FIG. 8 is a cross-section view taken along line 8 - 8 of FIG. 1 ; [0022] FIG. 9 is an assembled, perspective view of an electrical connector assembly in accordance with the second embodiment of the present invention; [0023] FIG. 10 is an exploded, perspective view of a plug connector in accordance with the second embodiment of the present invention; [0024] FIG. 11 is a view similar to FIG. 10 , but viewed from a different aspect; [0025] FIG. 12 is a perspective view of an additional grounding contact of the plug connector; [0026] FIG. 13 is an assembled, perspective view of the plug connector in accordance with the second embodiment of the present invention; [0027] FIG. 14 is an exploded, perspective view of the receptacle connector in accordance with the second embodiment of the present invention; [0028] FIG. 15 is a view similar to FIG. 14 , but viewed from a different aspect; [0029] FIG. 16 is an assembled, perspective view of FIG. 15 ; and [0030] FIG. 17 is a cross-section view taken along line 17 - 17 of FIG. 9 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0031] In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be obvious to those skilled in the art that the present invention may be practiced without such specific details. In other instances, well-known circuits have been shown in block diagram form in order not to obscure the present invention in unnecessary detail. For the most part, details concerning timing considerations and the like have been omitted inasmuch as such details are not necessary to obtain a complete understanding of the present invention and are within the skills of persons of ordinary skill in the relevant art. [0032] Reference will be made to the drawing figures to describe the present invention in detail, wherein depicted elements are not necessarily shown to scale and wherein like or similar elements are designated by same or similar reference numeral through the several views and same or similar terminology. [0033] Referring to FIGS. 1-4 , an electrical connector assembly 100 in accordance with the first embodiment of the present invention comprises a plug connector 10 and a receptacle connector 20 mating with each other. The plug connector 10 and the receptacle connector 20 are power connectors for power transmission in the preferred embodiment of the present invention, but the connectors are not only restricted to power type connectors. Also, the plug connector 10 and the receptacle connector 20 are the electrical connectors in accordance with the present invention. [0034] In the first embodiment of the present invention, the plug connector 10 comprises a first insulative housing 1 , a plurality of first contacts 2 attached to the first insulative housing 1 , and an additional grounding contact 4 also attached to the first insulative housing 1 . The receptacle connector 20 comprises a second insulative housing 6 and a plurality of second contacts 7 attached to the second insulative housing 6 . The first contacts 2 and the additional grounding contact 4 electrically connect with the second contacts 7 for power transmission. [0035] please refer to FIGS. 1-2 , 4 - 5 and 8 , the first insulative housing 1 defines a first mating face 11 , a receiving cavity 12 recessed rearward from the first mating face 11 , and a surrounding rib 13 enlarged from the circumferential edges of the receiving cavity 12 . The receiving cavity 12 is circumscribed by opposite top wall 111 and bottom wall 112 , a pair of opposite sidewalls 113 , and a rear wall 114 . The bottom wall 112 defines a rectangular recess 14 behind the surrounding rib 13 . A plurality of horizontal and vertical partition racks 115 extend into the receiving cavity 12 to divide the receiving cavity 12 into three first contact-receiving passageways 121 arranged in triangle relationship for receiving the first contacts 2 and penetrating through the rear wall 114 . The horizontal and vertical partition racks 115 connect with one another to assure that at least two adjacent sides of each first contact 2 are surrounded by the partition racks 115 . [0036] Please refer to FIGS. 5-6 and 8 , the first contacts 2 are three power contacts arranged in triangle relationship and received in the first contact-receiving passageways 121 . The two first contacts 2 aligning with each other and arranged on the same horizontal line are a positive contact and a negative contact in power transmission. The first contact 2 located at the top of the triangle is a grounding contact in power transmission. Each first contact 2 is of straight shape with a certain height and comprises a first retaining portion 21 interferentially engaged with the rear wall 114 of the first insulative housing 1 , a first connecting portion 22 extending rearward from the first retaining portion 21 to be exposed beyond the rear wall 114 for electrically connecting with wires (not shown), a flat first contacting portion 23 extending forward from the first retaining portion 21 , and a forward end 24 extending forward from the first contacting portion 23 ( FIG. 6 ). The forward end 24 is shrunk from the first contacting portion 23 with width and thickness both smaller that those of the first contacting portion 23 . The first contacting portion 23 has a contacting surface 231 behind the forward end 24 . When the first contacts 2 are retained in the first insulative housing 1 , the contacting portions 23 and the forward ends 24 are all exposed in the receiving cavity 12 , the connecting portions 22 extend beyond the rear wall 114 . The forward end 24 ha a front face 241 close to the first mating face 11 and an extending face 242 located at the same side as that of the contacting surface 231 . [0037] Since the forward ends 24 are located closer to the first mating face 11 , the forward ends 24 are easier to be touched by fingers or other things, or covered by dust from outside, all cause the forward ends 24 (especially the front faces 241 thereof) are prone to be polluted or damaged, further influence the stability of power transmission or raise unsafe problems. Please refer to FIGS. 5 and 6 , a protecting insulator 3 is overmolded with the forward end 24 of the first contact 2 in the preferred embodiment of the present invention which protects the forward end 24 from the problems described above. Of course, in an alternative embodiment, the protecting insulators 3 also can be assembled to the forward ends 24 of the first contacts 2 . The protecting insulator 3 is a hollow cuboid with one open end toward the forward end 24 of the first contact 2 . The protecting insulator 3 comprises a front end portion 31 covering the front face 241 of the forward end 24 and a cover portion 32 extending rearward from the end portion 31 to cover the extending faces 242 . Therefore, the insulated area is extended into inner section of the receiving cavity 12 which protects the contacting portion 23 from being polluted or damaged. The problems addressed above are solved to assure stability of power transmission and safety. [0038] In addition, the outer surface 321 of the cover portion 32 is coplanar with the contacting surface 231 for assuring the stability of the second contact 7 of the receptacle connector 20 sliding along the outer surface 321 and the contacting surface 231 . [0039] Please refer to FIGS. 5 and 8 , the additional grounding contact 4 is longitudinal and located below the grounding first contact 2 and together received in the same first contact-receiving passageway 121 with the grounding first contact 2 . The additional grounding contact 4 comprises an additional retaining portion 41 retained in the first insulative housing 2 , an additional connecting portion 42 extending rearward from the additional retaining portion 41 and beyond the first insulative housing 2 , and an additional contacting portion 43 extending forward from the additional retaining portion 41 and forming a contacting end 430 curved upward slightly. The contacting end 430 is located below a front section of the outer surface 321 of the protecting insulator 3 to assure that the additional grounding contact 4 electrically contacts the grounding second contact 7 of the receptacle connector 20 after the grounding first contact 2 . That means, the additional grounding contact 4 and the grounding first contact 2 form electrical connection with the same grounding second contact 7 . Thus, the additional grounding contact 4 is a spare grounding contact to assure an always grounding function even when the grounding first contact 2 is invalid. The grounding function is very important for high-power, high-voltage power connectors. [0040] Please refer to FIGS. 2 and 7 - 8 , the second insulative housing 6 comprises a second mating face 61 and a plurality of second contact-receiving passageways 60 recessed forward from the second mating face 61 . A protection block 62 protrudes upward from a bottom surface of each second contact-receiving passageway 60 and extends forward from the second mating face 60 into the second contact-receiving passageway 60 a certain distance. In FIGS. 2 and 8 , a latch arm 63 is disposed at a bottom of the second insulative housing 6 for latching with the recess 14 of the first insulative housing 1 . The latch arm 63 comprises a latch section 631 and a pressing section 632 respectively at opposite ends of the latch arm 63 . [0041] The second contact 7 comprises a flat second retaining portion 71 retained in the second insulative housing 6 , an elastic second contacting portion 72 extending rearward from the second retaining portion 71 and bending upwardly slightly, and a second connecting portion 74 extending forward from the second retaining portion 71 beyond the second insulative housing 6 for electrically connecting with wires (not shown). The second contacting portion 72 comprises an elastic contacting free end 73 with certain deformation ability. In FIG. 8 , when the second contacts 7 are retained in the second insulative housing 6 , the elastic second contacting portions 72 extend beyond upper surfaces of the protection blocks 62 . While, when the plug connector 10 and the receptacle connector 20 mate with each other, the elastic second contacting portions 72 are compressed by the contacting surfaces 231 of the second contacts 2 . The free ends 73 are compressed to be below the upper surfaces of the protection blocks 62 , thus, the second contacts 7 are prevented from being touched or damaged by outside. Correspondingly, the second contacts 7 also comprise three power contacts in triangle relationship in the preferred embodiment of the present invention, a positive second contact, a negative second contact and a grounding second contact 7 located at the top point of the triangle. Of course, the three second contact-receiving passageways 60 are also arranged in triangle relationship with the top second contact-receiving passageway 60 defines an additional contact-receiving passageway 65 at the bottom thereof to protrude through the protection block 62 . [0042] Please refer to FIG. 8 , when the plug connector 10 mates with the receptacle connector 20 , the second insulative housing 6 is received in the receiving cavity 12 of the first insulative housing 1 . The protection blocks 62 guide the first contacts 2 into the second contact-receiving passageways 60 to form electrical connection with the second contacts 7 . During the mating process, the elastic second contacting portion 72 slides along the outer surface 321 of the cover portion 32 firstly and then slide beyond the cover portion 32 to finally form electrical connection with the contacting surface 231 of the first contacting portion 23 . At the same time, the latch section 631 of the latch arm 63 ′ protrudes into the recess 14 of the first insulative housing 1 to improve the retention force between the plug connector 10 and the receptacle connector 20 . The additional grounding contact 4 protrudes through the additional contact-receiving passageway 65 to contact the grounding second contact 7 after the grounding first contact 2 contacts the grounding second contact 7 . [0043] When need to separate the plug connector 10 and the receptacle connector 20 , user just needs to press the pressing section 632 of the latch arm 63 downward, the latch section 631 is caused to be separated from the recess 14 . In alternative embodiments, the latch arm 63 also can be disposed on the first insulative housing 1 of the plug connector 10 and the recess 14 is defined in the second insulative housing 6 which also can realize the same purpose. The first contacts 2 can be assembled to or insert-molded with the first insulative housing 1 , and the second contacts 7 also can be assembled to or insert-molded with the second insulative housing 6 . In addition, the additional grounding contact 4 also can be disposed in the second insulative housing 6 of the receptacle connector 20 after a skilled person in the art makes some simple changes to the second insulative housing 6 . [0044] FIGS. 9-17 disclose a second embodiment of the present invention, a plug connector 10 ′ and a receptacle connector 20 ′ of an electrical connector assembly 100 ′ have similar designs as described in the first embodiment. Hence, only differences will be introduced hereinafter. [0045] Compared with the plug connector 10 , the plug connector 10 ′ has different first contact structure. The first contacts 2 ′ have different first connecting portions 22 ′ which bend upward (for grounding first contact 2 ′) and downward (for power first contacts 2 ′). The plug connector 10 ′ also comprises a first retainer 5 ′ insert-molded with the first contacts 2 ′ together to form a first contact module. The protecting insulators 3 ′ are firstly insert-molded with the forward ends 24 ′ of the first contacts 2 ′, then the first retainer 5 ′ is insert-molded with the first contacts 2 and together assembled to the first insulative housing 1 ′. The first retainer 5 ′ is assembled to a rear end of the first insulative housing 1 ′ and has a pair of latch means 51 ′ on opposite lateral sides thereof to latch into a pair of through holes 117 ′ of locking means 116 ′ of the first insulative housing 1 ′. An L-shape cutout 52 ′ is recessed downward from a top edge of the first retainer 5 ′ for penetration of the additional grounding contact 4 ′. The first insulative housing 1 ′ defines an additional contact-receiving passageway 122 ′ with a front end thereof communicating with the top first contact-receiving passageway 121 ′. [0046] The additional grounding contact 4 ′ comprises an additional retaining portion 41 ′, a flat additional contacting portion 43 ′ extending forward from the additional retaining portion 41 ′, and an additional connecting portion 42 ′ extending rearward from the additional retaining portion 41 ′. The additional contacting portion 43 ′ penetrates through the additional contact-receiving passageway 122 ′ to be exposed in the top first contact-receiving passageway 121 ′ together with the grounding first contact 2 ′. A contacting end 430 ′ is stamped with a bump to electrically contact the grounding second contact 7 ′ of the receptacle connector 20 ′. The additional retaining portion 41 ′ comprises a main portion 412 ′ located in a horizontal surface and a rib 411 ′ extending vertically from one edge of the main portion 412 ′ to locate in a vertical surface. A plurality of first barbs 410 ′ and a plurality of second barbs 413 ′ are respectively formed at rear ends of the main portion 412 ′ and the rib 411 ′ to interferentially engage with inner walls of the additional contact-receiving passageways 122 ′ for retaining the additional grounding contact 4 ′ in the first insulative housing 1 ′. The additional connecting portion 42 ′ comprises an L-shape extended section 421 ′ mainly located in a horizontal surface and extending from the additional retaining portion 41 ′, and a connecting section 422 ′ bending upwardly from the extended section 421 ′. [0047] FIGS. 14-16 disclose the receptacle connector 20 ′. Compared with the receptacle connector 20 , the receptacle connector 20 ′ further comprises a second retainer 9 ′ retaining the second contacts 7 ′ together with the second insulative housing 6 ′. The second retainer 9 ′ is assembled to the second insulative housing 6 ′ after the second contacts 7 ′ are assembled to be received in the second contact-receiving passageways 60 ′ of the second insulative housing 6 ′. The second contacts 7 ′ are sandwiched between the second retainer 9 ′ and the second insulative housing 6 ′ to provide better support to the second connecting portions 74 ′. The second retainer 9 ′ forms a pair of latch means 95 ′ on opposite lateral sides to lock into through holes 66 ′ of a pair of locking means 64 ′ of the second insulative housing 6 ′ to attach the second retainer 9 ′ tightly to the second insulative housing 6 ′. Further, the second contacting portion 71 ′ is of bifurcated shape to improve elasticity thereof. [0048] Since the plug connector 10 , 10 ′ and the receptacle connector 20 , 20 ′ are high-power power connectors, heat radiation issue must be considered. In the second embodiment of the present invention, heat-radiation structures are designed. The first insulative housing 1 ′ defines a plurality of heat-radiating holes 17 ′ to communicate with at least one first contact-receiving passageway 121 ′, while, the second insulative housing 6 ′ defines a plurality of heat-radiating holes 67 ′ to communicate with at least one second contact-receiving passageway 60 ′. In addition, the second retainer 9 ′ also defines a plurality of heat-radiating passages 97 ′ to communicate with at least one second contact-receiving passageway 60 ′. These heat-radiating structures 17 ′, 67 ′ and 97 ′ communicate the first and second contact-receiving passageways 121 ′, 60 ′ with outside to radiate heat generated by mated first and second contacts 2 ′, 7 ′ to the outside in time to satisfy the heat-radiating requirement. [0049] It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. For example, the tongue portion is extended in its length or is arranged on a reverse side thereof opposite to the supporting side with other contacts but still holding the contacts with an arrangement indicated by the broad general meaning of the terms in which the appended claims are expressed.

An electrical connector includes an insulative housing, at least one contact and at least one protecting insulator. The insulative housing defines a mating direction, a mating face and a receiving cavity recessed from the mating face along said mating direction. The at least one contact is received in the insulative housing and includes a contacting portion exposed into the receiving cavity, a retaining portion extending from one end of the contacting portion to be interferentially received in the insulative housing, and a forward end extending from the other end of the contacting portion to locate more closely to the mating face of the insulative housing than the contacting portion, and a connecting portion extending from the retaining portion to be exposed beyond the insulative housing. The protecting insulator entirely covers the forward end of the at least one contact.

CROSS REFERENCE TO RELATED APPLICATIONS The present application is a continuation of U.S. patent application Ser. No. 13/658,735, filed Oct. 23, 2012, entitled, “VIRTUAL MULTICARRIER DESIGN FOR ORTHOGONAL FREQUENCY DIVISION MULTIPLE ACCESS COMMUNICATIONS,” which is a continuation of U.S. patent application Ser. No. 12/242,755 filed Sep. 30, 2008, entitled, “VIRTUAL MULTICARRIER DESIGN FOR ORTHOGONAL FREQUENCY DIVISION MULTIPLE ACCESS COMMUNICATIONS,” the entire specification of which is hereby incorporated by reference in its entirety for all purposes. FIELD Embodiments of the present disclosure relate to the field of wireless access networks, and more particularly, to virtual multicarrier design for orthogonal frequency division multiple access communications in said wireless access networks. BACKGROUND Orthogonal frequency division multiple access (OFDMA) communications use an orthogonal frequency-division multiplexing (OFDM) digital modulation scheme to deliver information across broadband networks. OFDMA is particularly suitable for delivering information across wireless networks. The OFDM digital modulation scheme uses a large number of closely-spaced orthogonal subcarriers to carry information. Each subcarrier is capable of carrying a data stream across a network between OFDMA terminals. OFDMA-based communication systems are well known to have out of band emission (OOBE) issues that result in intercarrier interference (ICI). Prior art networks control this ICI by providing guard bands, e.g., unused subcarriers, between adjacent carriers. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals designate like structural elements. Embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings. FIG. 1 illustrates a wireless communication environment in accordance with embodiments of this disclosure. FIG. 2 is a flowchart depicting operations of a base station in accordance with some embodiments. FIG. 3 is a flowchart depicting operations of a mobile station in accordance with some embodiments. FIG. 4 is a graph illustrating OOBE on two adjacent carriers in accordance with some embodiments. FIG. 5 illustrates various views of a configuration of assigned bandwidth in accordance with some embodiments. FIG. 6 illustrates an OFDMA frame in accordance with some embodiments. FIG. 7 illustrates a multicarrier transmission being processed with and without reuse of guard band subcarriers in accordance with some embodiments. FIG. 8 illustrates how teachings of various embodiments facilitate a flexible deployment and upgrading of network equipment in accordance with some embodiments. FIG. 9 illustrates a computing device capable of implementing a virtual carrier terminal in accordance with some embodiments. DETAILED DESCRIPTION In the following detailed description, reference is made to the accompanying drawings which form a part hereof wherein like numerals designate like parts throughout, and in which is shown by way of illustration embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments in accordance with the present invention is defined by the appended claims and their equivalents. Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments of the present invention; however, the order of description should not be construed to imply that these operations are order dependent. For the purposes of the present invention, the phrase “A and/or B” means “(A), (B), or (A and B).” For the purposes of the present invention, the phrase “A, B, and/or C” means “(A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).” The description may use the phrases “in an embodiment,” or “in embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present invention, are synonymous. Embodiments of the present disclosure describe virtual multicarrier designs for OFDMA communications as may be used by multicarrier transmission schemes presented in, e.g., the Institute of Electrical and Electronics Engineers (IEEE) 802.16—2004 standard along with any amendments, updates, and/or revisions (e.g., 802.16m, which is presently at predraft stage), 3 rd Generation Partnership Project (3GPP) long-term evolution (LTE) project, ultra mobile broadband (UMB) project (also referred to as “3GPP2”), etc. FIG. 1 illustrates a wireless communication environment 100 in accordance with an embodiment of this disclosure. In this embodiment, the wireless communication environment 100 is shown with three wireless communication terminals, e.g., base station 104 , mobile station 108 , and mobile station 112 , communicatively coupled to one another via an over-the-air (OTA) interface 116 . In various embodiments, the mobile stations 108 and 112 may be a mobile computer, a personal digital assistant, a mobile phone, etc. The base station 104 may be a fixed device or a mobile device that may provide the mobile stations 108 and 112 with network access. The base station 104 may be an access point, a base transceiver station, a radio base station, a node B, etc. The wireless communication devices 104 , 108 , and 112 may have respective antenna structures 120 , 124 , and 128 to facilitate the communicative coupling. Each of the antenna structures 120 , 124 , and 128 may have one or more antennas. An antenna may be a directional or an omnidirectional antenna, including, e.g., a dipole antenna, a monopole antenna, a patch antenna, a loop antenna, a microstrip antenna or any other type of antenna suitable for transmission/reception of radio frequency (RF) signals. Briefly, the base station 104 may have a baseband processing block (BPB) 132 coupled to a transmitter 136 . The BPB 132 may be configured to encode input data, which may be received in a binary format, as an OFDM signal on logical subcarriers of a virtual carrier. The logical subcarriers may be mapped to physical subcarriers from at least two adjacent physical carriers. The BPB 132 may then control the transmitter 136 to transmit the OFDM signal on the physical subcarriers. FIG. 2 is a flowchart depicting operations of the base station 104 in accordance with some embodiments. At block 204 , an encoder 140 of the BPB 132 may receive input data from upper layers of the base station 104 . At block 208 , the encoder 140 may encode the input data into frequency domain OFDM signal having logical subcarriers of a virtual carrier. At block 212 , the encoder 140 may map the logical subcarriers to physical subcarriers of one or more physical carriers according to a mapping scheme provided by the mapper 144 . In some embodiments, the mapping scheme may map indices of the logical subcarriers to indices of the physical subcarriers. For example, consider a simple embodiment in which the encoder 140 encodes an OFDMA signal onto 20 logical subcarriers of a virtual carrier. The logical subcarriers may have indices 1-20. A mapping scheme may map the logical subcarrier indices 1-20 to physical subcarrier indices 1-5 of a first physical carrier, physical subcarrier indices 1-5 of a second physical carrier, and physical subcarrier indices 1-10 of a third physical carrier. In an actual implementation, the number of subcarriers will be significantly higher. Furthermore, the total number of logical subcarriers need not be equal to the total number of physical subcarriers as is described in this example. The frequency domain OFDM signal may be provided to an inverse fast Fourier transformer (IFFT) 148 that transforms the signal into a time domain OFDM signal, having a plurality of time domain samples for associated physical subcarriers. At block 216 , the transmitter 136 may be controlled to transmit the physical subcarriers. The transmitter 136 may provide a variety of physical layer processing techniques, e.g., adding cyclic prefix, upconverting, parallel-to-serial conversion, digital-to-analog conversion, etc. to effectuate the transmission. The receiving process of the mobile stations may operate in a manner that complements the transmitting process described above. FIG. 3 is a flowchart depicting operations of the mobile station 108 in accordance with some embodiments. At block 304 , a receiver 152 of the mobile station 108 may receive the physical carriers that carry the OFDM signal via the OTA interface 116 , process the OFDM signal and present it, as a time domain OFDM signal, to a BPB 156 . The complementary physical layer processing techniques of the receiver 152 may include, e.g., removing cyclic prefix, down converting, serial-to-parallel conversion, analog-to-digital conversion, etc. to effectuate reception and facilitate subsequent processing. The BPB 156 may include a fast Fourier transformer (FFT) 160 to receive the time domain OFDM signal from the receiver 152 . The FFT 160 may generate a frequency domain OFDM signal and forward the signal to a decoder 164 . At block 308 , the decoder 164 may map the physical subcarriers of the physical carriers to logical subcarriers of the virtual carrier according to the mapping scheme provided by mapper 168 . In some embodiments, information related to the mapping scheme may be transmitted to the mobile station 108 from the base station 104 in, e.g., downlink (DL) control messages, DL broadcast channel messages, etc. At block 312 , the decoder 164 may decode the logical subcarriers to retrieve the transmitted data. This data may then be output to upper layers of the mobile station 108 at block 316 . The use of virtual multicarriers for communications between terminals may, for example, allow a base station to scale its bandwidth, provide support for mobile stations having various bandwidths, facilitate deployment and upgrading of network equipment due, at least in part, to legacy support, etc. These aspects will be discussed in further detail below. While the described embodiments discuss the base station 104 transmitting, and the mobile station 108 receiving, on virtual carriers, other embodiments may additionally/alternatively include the mobile station 108 transmitting, and the base station 104 receiving, on virtual channels. Furthermore, various embodiments of this disclosure describe aligning subcarriers of adjacent physical carriers of a virtual carrier. As used herein, subcarrier of adjacent physical carriers may be aligned if the spacing between a subcarrier of a first physical carrier and a subcarrier of a second physical carrier is equal to, or a multiple of, a spacing between adjacent subcarriers within the first (or second) physical carrier. This alignment may reduce, either in part or in total, ISI, which may, in turn, enable use of subcarriers traditional reserved for guard band. Using these subcarriers for data transmission may increase an overall spectrum utilization ratio. To understand the effect of subcarrier spacing between adjacent carriers, consider an OFDM signal that is expressed in the time domain as: y ⁡ ( t ) = ∑ k = 0 M - 1 ⁢ ⁢ X ⁡ ( k ) ⁢ ⅇ j ⁢ ⁢ 2 ⁢ ⁢ π ⁢ ⁢ q k ⁢ Δ ⁢ ⁢ ft , ⁢ 0 ≤ t ≤ T u , ⁢ T u ⁢ Δ ⁢ ⁢ f = 1 , ⁢ q k ⁢ : ⁢ ⁢ int ∈ [ - N 2 , N 2 - 1 ] Eq . ⁢ 1 and in the frequency domain as: y ⁡ ( t ) = T u ⁢ ∑ k = 0 M - 1 ⁢ ⁢ X ⁡ ( k ) ⁢ Sinc ⁡ ( ( f - q k ⁢ Δ ⁢ ⁢ f ) ⁢ T u ) ⁢ ⅇ - j ⁢ ⁢ 2 ⁢ ⁢ π ⁡ ( g - q k ⁢ Δ ⁢ ⁢ f ) ⁢ T u Eq . ⁢ 2 where M is the number of used subcarriers, T u is useful symbol duration, q k is the position, or index, of the used subcarrier. Eq. 2 may be used to calculate the average power spectrum as: E ⁢ {  Y ⁡ ( f )  2 } = ⁢ σ s 2 ⁢ ∑ k = 0 M - 1 ⁢ ⁢  Sinc ( ( f - q k ⁢ Δ ⁢ ⁢ f ) ⁢ T u  2 = ⁢ σ s 2 ⁢  sin ⁡ ( β ⁢ ⁢ π )  2 ⁢ ∑ k = 0 M - 1 ⁢ ⁢ 1  π ⁡ ( f - q k ⁢ Δ ⁢ ⁢ f ) ⁢ T u  2 , Eq . ⁢ 4 Eq . ⁢ 3 where β is a misalignment factor that ranges from 0˜1, and σ s is an expression of subcarrier energy. FIG. 4 is a graph illustrating OOBE on two adjacent carriers 404 and 408 that have a maximum misalignment factor of 0.5, a 10 MHz bandwidth, 840 subcarriers, and no low-pass filter. As can be seen, there is a 0 to −29 dB interference signal at guard band subcarriers. The power of the interference signal from a neighboring carrier may be: 10 ⁢ ⁢ log ⁡ ( σ s 2 ⁢ ∑ k = 0 M - 1 ⁢ ⁢ 1  π ⁡ ( f - q k ⁢ Δ ⁢ ⁢ f ) ⁢ T u  2 ) + 10 ⁢ ⁢ log (  sin ( β ⁢ ⁢ π  2 ) . Eq . ⁢ 5 When the subcarriers of adjacent carriers are aligned, as described in accordance with various embodiments, the alignment factor β=0 and the value of the expression “10 log(|sin(βπ| 2 )” of Eq. 5 will go to negative infinity. Accordingly, there will be no (or very little) interference due to OOBE after the neighboring carriers are well aligned. The alignment of the subcarriers in adjacent carriers may be accomplished in a variety of ways. In one embodiment, the IFFT 148 may be one transformer that utilizes all of the frequency domain samples corresponding to one virtual channel as one vector input group. In this manner, the subcarriers across an entire virtual carrier of, e.g., a 20 MHz band, may then be equally spaced. The 20 MHz band may be subdivided into various physical carriers, e.g., two 5 MHz and one 10 MHz carriers. In another embodiment, the IFFT 148 may include more than one transformer, e.g., it may include a transformer for each physical carrier, with each transformer producing a physical carrier. In this embodiment, each of the distinct transformers may perform transform functions on distinct vector input groups of the frequency domain samples. When separate transformers are used to independently produce physical carriers, care may be taken to ensure that subcarriers of adjacent carriers are aligned. In various embodiments, subcarrier alignment may be performed by changing the channel raster to, e.g., 175 kHz; by shifting the center frequency of adjacent carriers; and/or to change the subcarrier spacing to, e.g., 12.5 kHz. FIG. 5 illustrates various views of a configuration of assigned bandwidth 500 in accordance with embodiments of this disclosure. In this embodiment, the assigned bandwidth 500 may be a 20 MHz band. The base station 104 may configure the assigned bandwidth 500 as three physical carriers, e.g., physical carrier (PC) 504 , PC 508 , and PC 512 . PCs 504 and 508 may be 5 MHz bands, while the PC 512 may be a 10 MHz band. A “physical carrier,” as used herein, may refer to a continuous spectrum of radio frequencies in which at least one mobile station of the wireless communication environment 100 is capable of, and restricted to, communicating with the base station. The configured PCs may be viewed differently according to the capabilities of the receiving terminal. A terminal capable of communicating with virtual carriers (hereinafter also referred to as “VC terminal”) may have a VC terminal view 516 , while a terminal not able to communicate with virtual carriers (hereinafter also referred to as “legacy terminal”) may have a legacy terminal view 520 . The base station 104 may adapt communications accordingly. The base station 104 may communicate with a VC terminal having a 20 MHz receiver by a virtual carrier shown in the VC terminal view 516 . With the subcarriers of adjacent PCs being aligned, e.g., PC 504 and 508 and/or PC 508 and PC 512 , the base station 104 may utilize at least some of the edge subcarrier groups, which are reserved as guard band subcarriers in prior art systems, for communication. As used herein, “an edge subcarrier group” may be a group of consecutive subcarriers of a particular PC that includes a subcarrier that is adjacent to subcarriers of an adjacent PC. Edge subcarrier groups that are adjacent to a PC of a common virtual carrier may be referred to as interior edge subcarrier groups. In FIG. 5 , the interior edge subcarrier groups may be groups 524 , 528 , 532 , and 536 . Given the subcarrier alignment, these interior edge subcarrier groups may be utilized for communications. However, in order to avoid ICI with PCs external to the virtual carrier, the groups 540 and 544 , or external edge subcarrier groups, may be reserved for a guard band. The base station 104 may communicate with legacy terminal by PC 504 , 508 , or 512 as seen in the legacy terminal view 520 . Each legacy terminal will only be capable of receiving data communications on one of the PCs. Furthermore, unlike the VC terminals, a legacy terminal will see the edge subcarrier groups 524 , 528 , 532 , and 536 as being reserved for a guard band. Accordingly, the legacy terminal will not be able to transmit or receive on subcarriers within these groups. Communications between the base station 104 and a legacy terminal will not compromise a contemporaneous communication of the base station 104 and a VC terminal that uses the full range of available subcarriers. FIG. 6 illustrates an OFDM frame 600 in accordance with embodiments of the present disclosure. In this embodiment, PCs 604 , 608 , and 612 are shown. PCs 604 and 608 may each have, e.g., a 10 MHz band, while PC 612 may have a 5 MHz band. Each PC may include a preamble 616 , edge subcarriers 620 , and a broadcast messaging section 624 . In one embodiment, the base station 104 may encode data onto a first virtual carrier (VC1) that includes all three of the PCs 604 , 608 , and 612 . In this embodiment, one or more receiving terminals including, e.g., mobile station 108 , may have a 25 MHz receiver that accommodates the entire range of VC1. The base station 104 may transmit allocation information on a common messaging section 628 to communicate DL and UL allocations to VC terminals. In this embodiment, the base station 104 may use the common messaging section 628 to inform the mobile station 108 that downlink communications will be sent to the mobile station 108 at resource 632 and that the mobile station 108 may upload information to the base station 104 at resource 636 . As can be seen, the resource 632 may incorporate edge subcarriers of PCs 604 and 608 . The base station 104 may also encode data onto other virtual carriers that include various subsets of adjacent PCs. For example, the base station 104 may encode data onto a second virtual carrier (VC2) that includes only PC 604 and PC 608 . VC2 may be used for communications with VC terminals having 20 MHz receivers. Hereinafter, a VC terminal having a 20 MHz receiver may also be referred to as a 20 MHz VC terminal. In this embodiment, the base station 104 may communicate, to a particular 20 MHz VC terminal, DL allocations at resource 640 and UL allocations at resource 644 , which also includes edge subcarrier groups of PC 604 and PC 608 . The base station 104 may additionally/alternatively encode data onto a third virtual carrier (VC1) that includes only PC 608 and PC 612 . VC3 may be used for communications with 15 MHz VC terminals. In this embodiment, the base station 104 may communicate, to a particular 15 MHz VC terminal, DL allocations at resource 652 and UL allocations at resource 656 , which may include edge subcarrier groups of PC 608 and PC 612 . The base station 104 may also use individual PCs to communicate with legacy terminals. In this embodiment, e.g., 10 MHz legacy terminals may communicate with the base station 104 on PC 608 . The base station 104 may communicate, to a particular 10 MHz legacy terminal, DL allocations at resource 660 and UL allocations at resource 664 . It may be noted that communications between the base station 104 and the legacy terminal may not use the edge subcarrier groups of the PC 608 . However, these same edge subcarrier groups of PC 608 may be used for communications between the base station 104 and VC terminals without adversely affecting the communications with the legacy terminal. Dividing an assigned bandwidth into various PCs, which may or may not have the same bandwidths, and utilizing the different PCs in various combinations to provide a variety of virtual carriers, may allow base stations endowed with teachings of this disclosure to scale communications to terminals configured to operate on any number of different bandwidths. In some embodiments, one or more of the PCs of a virtual carrier may be used as a data only pipe. For example, in VC1 control and signaling information may be transmitted in PC 608 while the entire spectrum of PC 612 is reserved for data communications. However, if a PC is being used to communicate with a legacy terminal, some amount of control and signaling information may be desired in said PC. FIG. 7 illustrates a multicarrier transmission being processed with and without reuse of edge subcarriers in accordance with an embodiment of the present disclosure. Referring to FIG. 7( a ) , a virtual carrier, including PCs 704 and 708 , may be used for transmissions to a VC terminal and PC 704 may be used for transmissions to a legacy terminal. Each of the PCs 704 and 708 may have 10 MHz bands. Data may be distributed among the PCs according to a partial usage subchannelization (PUSC) scheme with each PC having 841 subcarriers (not including edge carrier groups) over a 9.1984 MHz band. In order to align the two PCs, the center frequency of PC 708 may be shifted by 3.125 KHz, which may result in the center frequencies of the two bands being 9.996875 MHz apart. The value of this frequency shift is purely exemplary and may be adjusted in various embodiments according to, e.g., carrier bandwidth, subcarrier spacing, etc. FIG. 7( b ) illustrates subcarriers 712 that represent the 841 subcarriers of the PC 704 , subcarriers 716 that represent the 73 guard subcarriers, and subcarriers 720 that correspond to the 841 subcarriers of the PC 708 . The legacy terminal may include a 10 MHz band selection filter 724 that corresponds to the PC 704 . FIG. 7( c ) illustrates data tones that may result from the sampling of the subcarriers of FIG. 7( b ) when all of the subcarriers, including the subcarriers 716 , are used for data transmission in accordance with an embodiment of the present disclosure. In this embodiment, a common sampling rate of 11.2 MHz for a 10 MHz carrier is used. FIG. 7( d ) illustrates data tones that may result from the sampling of the subcarriers of FIG. 7( b ) when the subcarriers 716 are not used for data transmission in accordance with an embodiment of the present disclosure. As can be seen by FIGS. 7( c ) and 7( d ) , the values of the subcarriers that are used by the legacy terminal, e.g., subcarriers 712 , are not impacted regardless of whether or not the guard band subcarriers 716 are used. Therefore, data transmissions to a legacy terminal will not be affected, even when the guard subcarriers of the PC 708 are used and the PC 708 is effectively shifted closer to the PC 704 due to the alignment processing. FIG. 8 illustrates how teachings of various embodiments facilitate a flexible deployment and upgrading of network equipment in accordance with various embodiments of this disclosure. At an initial stage 804 , 20 MHz of assigned bandwidth may be configured into two 10 MHz bands. The first band may be designated a PC 808 to be used only for communications with legacy terminals. The other 10 MHz band may be reserved. At deployment stage 812 , the formally reserved band may be configured as PC 816 to be used only for communications with VC terminals. At deployment stage 820 , the legacy-only PC 808 may be configured as PC 824 to be used for communications with legacy and/or VC terminals. This stage may be similar to the embodiment discussed with reference to FIG. 6 . At deployment stage 828 , the legacy/VC PC 824 may be configured as PC 832 to be used only for communications with VC terminals. In this embodiment, the 20 MHz bandwidth may thus be used as two different 10 MHz bands or one 20 MHz band for various VC terminals of the wireless communication environment. FIG. 9 illustrates a computing device 900 capable of implementing a VC terminal in accordance with various embodiments. As illustrated, for the embodiments, computing device 900 includes processor 904 , memory 908 , and bus 912 , coupled to each other as shown. Additionally, computing device 900 includes storage 916 , and communication interfaces 920 , e.g., a wireless network interface card (WNIC), coupled to each other, and the earlier described elements as shown. Memory 908 and storage 916 may include in particular, temporal and persistent copies of coding and mapping logic 924 , respectively. The coding and mapping logic 924 may include instructions that when accessed by the processor 904 result in the computing device 900 performing encoding/decoding and mapping operations described in conjunction with various VC terminals in accordance with embodiments of this disclosure. In particular, these coding and mapping operations may allow a VC terminal, e.g., base station 104 and/or mobile station 108 , to transmit and/or receive communications over virtual carriers as described herein. In various embodiments, the memory 908 may include RAM, dynamic RAM (DRAM), static RAM (SRAM), synchronous DRAM (SDRAM), dual-data rate RAM (DDRRAM), etc. In various embodiments, the processor 904 may include one or more single-core processors, multiple-core processors, controllers, application-specific integrated circuits (ASICs), etc. In various embodiments, storage 916 may include integrated and/or peripheral storage devices, such as, but not limited to, disks and associated drives (e.g., magnetic, optical), universal serial bus (USB) storage devices and associated ports, flash memory, read-only memory (ROM), nonvolatile semiconductor devices, etc. In various embodiments, storage 916 may be a storage resource physically part of the computing device 900 or it may be accessible by, but not necessarily a part of, the computing device 900 . For example, the storage 916 may be accessed by the computing device 900 over a network. In various embodiments, computing device 900 may have more or less components, and/or different architectures. Although certain embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments in accordance with the present invention be limited only by the claims and the equivalents thereof.

Embodiments of the present invention provide a virtual multicarrier design for orthogonal frequency division multiple access communications. Other embodiments may be described and claimed.

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority of U.S. Provisional Application Ser. No. 60/710,682, filed Aug. 22, 2005, having attorney docket no. 05542-613P01, entitled “SPECTRUM BASED ENDPOINTING FOR CHEMICAL MECHANICAL POLISHING.” BACKGROUND The present invention relates to generally to chemical mechanical polishing of substrates. An integrated circuit is typically formed on a substrate by the sequential deposition of conductive, semiconductive, or insulative layers on a silicon wafer. One fabrication step involves depositing a filler layer over a non-planar surface and planarizing the filler layer. For certain applications, the filler layer is planarized until the top surface of a patterned layer is exposed. A conductive filler layer, for example, can be deposited on a patterned insulative layer to fill the trenches or holes in the insulative layer. After planarization, the portions of the conductive layer remaining between the raised pattern of the insulative layer form vias, plugs, and lines that provide conductive paths between thin film circuits on the substrate. For other applications, such as oxide polishing, the filler layer is planarized until a predetermined thickness is left over the non planar surface. In addition, planarization of the substrate surface is usually required for photolithography. Chemical mechanical polishing (CMP) is one accepted method of planarization. This planarization method typically requires that the substrate be mounted on a carrier or polishing head. The exposed surface of the substrate is typically placed against a rotating polishing disk pad or belt pad. The polishing pad can be either a standard pad or a fixed abrasive pad. A standard pad has a durable roughened surface, whereas a fixed-abrasive pad has abrasive particles held in a containment media. The carrier head provides a controllable load on the substrate to push it against the polishing pad. A polishing slurry is typically supplied to the surface of the polishing pad. The polishing slurry includes at least one chemically reactive agent and, if used with a standard polishing pad, abrasive particles. One problem in CMP is determining whether the polishing process is complete, i.e., whether a substrate layer has been planarized to a desired flatness or thickness, or when a desired amount of material has been removed. Overpolishing (removing too much) of a conductive layer or film leads to increased circuit resistance. On the other hand, underpolishing (removing too little) of a conductive layer leads to electrical shorting. Variations in the initial thickness of the substrate layer, the slurry composition, the polishing pad condition, the relative speed between the polishing pad and the substrate, and the load on the substrate can cause variations in the material removal rate. These variations cause variations in the time needed to reach the polishing endpoint. Therefore, the polishing endpoint cannot be determined merely as a function of polishing time. SUMMARY In one general aspect, the invention features an assembly for chemical mechanical polishing. The assembly includes a polishing pad having a polishing surface. The assembly includes a solid window situated in the polishing pad to provide optical access through the polishing pad. The solid window includes a first portion made from polyurethane and a second portion made from quartz. The first portion has a surface that is co planar with the polishing surface of the polishing pad. In another general aspect, the invention features a polishing pad that includes a polishing layer having a top surface and a bottom surface. The pad includes an aperture having a first opening in the top surface and a second opening in the bottom surface. The top surface is a polishing surface. The pad includes a window that includes a first portion made of soft plastic and a crystalline or glass like second portion. The window is transparent to white light. The window is situated in the aperture so that the first portion plugs the aperture and the second portion is on a bottom side of the first portion, wherein the first portion acts a slurry-tight barrier. In another general aspect, the invention features a method of making a polishing pad. The method includes placing mass of crystalline or glass like material in a mold of a polishing pad window, the mass being transparent to white light. The method includes dispensing a liquid precursor of a soft plastic material into the mold, the soft plastic material being transparent to white light. The method includes curing the liquid precursor to form a window that includes a first portion made of soft plastic material and a crystalline or glass like second portion. The method includes placing the window in a mold of a polishing pad. The method includes dispensing a liquid precursor of a polishing pad material into the mold of the polishing pad. The method includes curing the liquid precursor of the polishing pad material to produce the polishing pad, wherein the window is situated in the mold of the polishing pad so that, when the polishing pad is produced, the window is situated in the polishing pad so that the first portion acts a slurry-tight barrier. In another general aspect, the invention features a method of making a polishing pad. The method includes placing mass of crystalline or glass like materials in a mold of a polishing pad window, the mass being transparent to white light. The method includes dispensing a liquid precursor of a soft plastic material into the mold, the soft plastic material being transparent to white light. The method includes curing the liquid precursor to form a window that includes a first portion made of soft plastic material and a crystalline or glass like second portion. The method includes forming a polishing layer that includes an aperture, the polishing layer having a top surface and a bottom surface, the aperture having a first opening in the top surface and a second opening in the bottom surface, the top surface being a polishing surface. The method includes inserting the window in the aperture, the window being situated in the aperture so that the first portion plugs the aperture and the second portion is on a bottom side of the first portion, wherein the first portion acts a slurry-tight barrier. In another general aspect, the invention features a method of making a polishing pad. The method includes forming a first portion of a polishing pad window, the first portion having a recess and being transparent to white light. The method includes inserting a mass of crystalline or glass like material into the recess, the mass being transparent to white light. The method includes forming a polishing layer that includes an aperture, the polishing layer having a top surface and a bottom surface, the aperture having a first opening in the top surface and a second opening in the bottom surface, the top surface being a polishing surface. The method includes inserting the window in the aperture, the window being situated in the aperture so that the first portion plugs the aperture and the second portion is on a bottom side of the first portion, wherein the first portion acts a slurry-tight barrier. As used in the instant specification, the term substrate can include, for example, a product substrate (e.g., which includes multiple memory or processor dies), a test substrate, a bare substrate, and a gating substrate. The substrate can be at various stages of integrated circuit fabrication, e.g., the substrate can be a bare wafer, or it can include one or more deposited and/or patterned layers. The term substrate can include circular disks and rectangular sheets. Possible advantages of implementations of the invention can include one or more of the following. Endpoint determination can be made virtually without consideration of variations in polishing rate. Factors that affect polishing rate, for example, consumables, generally need not be considered. A flushing system can be less likely to dry out slurry on a substrate surface being polished. A polishing pad window can enhance the accuracy and/or precision of endpoint determination. The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the invention will become apparent from the description, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a chemical mechanical polishing apparatus. FIGS. 2A-2H show implementations of a polishing pad window. FIG. 3 shows an implementation of a flushing system. FIG. 4 shows an alternative implementation of the flushing system. FIG. 5 is an overhead view of a polishing pad and shows locations where in-situ measurements are taken. FIG. 6A shows a spectrum obtained from in-situ measurements. FIG. 6B illustrates the evolution of spectra obtained from in-situ measurements as polishing progresses. FIG. 7A shows a method for obtaining a target spectrum. FIG. 7B shows a method for obtaining a reference spectrum. FIGS. 8A and 8B show a method for endpoint determination. FIGS. 9A and 9B show an alternative method for endpoint determination. FIGS. 10A and 10B show another alternative method for endpoint determination. FIG. 11 shows an implementation for determining an endpoint. FIG. 12 illustrates peak-to-trough normalization of a spectrum. Like reference numbers and designations in the various drawings indicate like elements. DETAILED DESCRIPTION FIG. 1 shows a polishing apparatus 20 operable to polish a substrate 10 . The polishing apparatus 20 includes a rotatable disk-shaped platen 24 , on which a polishing pad 30 is situated. The platen is operable to rotate about axis 25 . For example, a motor can turn a drive shaft 22 to rotate the platen 24 . The polishing pad 30 can be detachably secured to the platen 24 , for example, by a layer of adhesive. When worn, the polishing pad 30 can be detached and replaced. The polishing pad 30 can be a two-layer polishing pad with an outer polishing layer 32 and a softer backing layer 34 . Optical access 36 through the polishing pad is provided by including an aperture (i.e., a hole that runs through the pad) or a solid window. The solid window can be secured to the polishing pad, although in some implementations the solid window can be supported on the platen 24 and project into an aperture in the polishing pad. The polishing pad 30 is usually placed on the platen 24 so that the aperture or window overlies an optical head 53 situated in a recess 26 of the platen 24 . The optical head 53 consequently has optical access through the aperture or window to a substrate being polished. The optical head is further described below. The window can be, for example, a rigid crystalline or glassy material, e.g., quartz or glass, or a softer plastic material, e.g., silicone, polyurethane or a halogenated polymer (e.g., a fluoropolymer), or a combination of the materials mentioned. The window can be transparent to white light. If a top surface of the solid window is a rigid crystalline or glassy material, then the top surface should be sufficiently recessed from the polishing surface to prevent scratching. If the top surface is near and may come into contact with the polishing surface, then the top surface of the window should be a softer plastic material. In some implementations the solid window is secured in the polishing pad and is a polyurethane window, or a window having a combination of quartz and polyurethane. The window can have high transmittance, for example, approximately 80% transmittance, for monochromatic light of a particular color, for example, blue light or red light. The window can be sealed to the polishing pad 30 so that liquid does not leak through an interface of the window and the polishing pad 30 . In one implementation, the window includes a rigid crystalline or glassy material covered with an outer layer of a softer plastic material. The top surface of the softer material can be coplanar with the polishing surface. The bottom surface of the rigid material can be coplanar with or recessed relative to the bottom surface of the polishing pad. In particular, if the polishing pad includes two layers, the solid window can be integrated into the polishing layer, and the bottom layer can have an aperture aligned with the solid window. Assuming that the window includes a combination of a rigid crystalline or glassy material and a softer plastic material, no adhesive need be used to secure the two portions. For example, in one implementation, no adhesive is used to couple the polyurethane portion to the quartz portion of the window. Alternatively, an adhesive that is transparent to white light can be used or an adhesive can be applied so that light passing through the window does not pass through the adhesive. By way of example, the adhesive can be applied only to the perimeter of the interface between the polyurethane and quartz portion. A refractive index gel can be applied to a bottom surface of the window. A bottom surface of the window can optionally include one or more recesses. A recess can be shaped to accommodate, for example, an end of an optical fiber cable or an end of an eddy current sensor. The recess allows the end of the optical fiber cable or the end of the eddy current sensor to be situated at a distance, from a substrate surface being polished, that is less than a thickness of the window. With an implementation in which the window includes a rigid crystalline portion or glass like portion and the recess is formed in such a portion by machining, the recess is polished so as to remove scratches caused by the machining. Alternatively, a solvent and/or a liquid polymer can be applied to the surfaces of the recess to remove scratches caused by machining. The removal of scratches usually caused by machining reduces scattering and can improve the transmittance of light through the window. FIGS. 2A-2H show various implementations of the window. As shown in FIG. 2A , the window can have two portions, a polyurethane portion 202 and a quartz portion 204 . The portions are layers, with the polyurethane portion 202 situated on top of the quartz portion 204 . The window can be situated in the polishing pad so that the top surface 206 of the polyurethane layer is coplanar with a polishing surface 208 of the polishing pad. As shown in FIG. 2B , the polyurethane portion 202 can have a recess in which the quartz portion is situated. A bottom surface 210 of the quartz portion is exposed. As shown in FIG. 2C , the polyurethane portion 202 can include projections, for example, projection 212 , that project into the quartz portion 204 . The projections can act to reduce the likelihood that the polyurethane portion 202 will be pulled away from the quartz portion 204 due to friction from the substrate or retaining ring. As shown in FIG. 2D , the interface between the polyurethane portion 202 and quartz portion 204 can be a rough surface. Such a surface can improve the strength of the coupling of the two portions of the window, also reducing the likelihood the polyurethane portion 202 will be pulled away from the quartz portion 204 due to friction from the substrate or retaining ring. As shown in FIG. 2E , the polyurethane portion 202 can have non-uniform thickness. The thickness at a location that would be in the path 214 of a light beam is less than the thickness at a location that would not be in the path 214 of the light beam. By way of example, thickness t 1 is less than thickness t 2 . Alternatively, the thickness can be less at the edges of the window. As shown in FIG. 2F , the polyurethane portion 202 can be attached to the quartz portion 204 by use of an adhesive 216 . The adhesive can be applied so that it would not be in the path 214 of the light beam. As shown in FIG. 2G , the polishing pad can include a polishing layer and a backing layer. The polyurethane portion 202 extends through the polishing layer and at least partially into the backing layer. The hole in the backing layer can be larger in size than the hole in the polishing layer, and the section of the polyurethane in the backing layer can be wider than the section of the polyurethane in the polishing layer. The polishing layer thus provides a lip 218 which overhangs the window and which can act to resist a pulling of the polyurethane portion 202 away from the quartz portion 204 . The polyurethane portion 202 conforms to the holes of the layers of the polishing pad. As shown in FIG. 2H , refractive index gel 220 can be applied to the bottom surface 210 of the quartz portion 204 so as to provide a medium for light to travel from a fiber cable 222 to the window. The refractive index gel 220 can fill the volume between the fiber cable 222 and the quartz portion 204 and can have a refractive index that matches or is between the indices of refraction of the fiber cable 222 and the quartz portion 204 . In implementations where the window includes both quartz and polyurethane portions, the polyurethane portion should have a thickness so that, during the life time of the polishing pad, the polyurethane portion will not be worn so as to expose the quartz portion. The quartz can be recessed from the bottom surface of the polishing pad, and the fiber cable 222 can extend partially into the polishing pad. The above described window and polishing pad can be manufactured using a variety of techniques. The polishing pad's backing layer 34 can be attached to its outer polishing layer 32 , for example, by adhesive. The aperture that provides optical access 36 can be formed in the pad 30 , e.g., by cutting or by molding the pad 30 to include the aperture, and the window can be inserted into the aperture and secured to the pad 30 , e.g., by an adhesive. Alternatively, a liquid precursor of the window can be dispensed into the aperture in the pad 30 and cured to form the window. Alternatively, a solid transparent element, e.g., the above described crystalline or glass like portion, can be positioned in liquid pad material, and the liquid pad material can be cured to form the pad 30 around the transparent element. In either of the later two cases, a block of pad material can be formed, and a layer of polishing pad with the molded window can be scythed from the block. With an implementation in which the window includes a crystalline or glass like first portion and a second portion made of soft plastic material, the second portion can be formed in the aperture of the pad 30 by applying the described liquid precursor technique. The first portion can then be inserted. If the first portion is inserted before the liquid precursor of the second portion is cured, then curing can bond the first and second portions. If the first portion is inserted after the liquid precursor is cured, then the first and second potions can be secured by using an adhesive. The polishing apparatus 20 can include a flushing system to improve light transmission through the optical access 36 . There are different implementations of the flushing system. With implementations of the polishing apparatus 20 in which the polishing pad 30 includes an aperture instead of a solid window, the flushing system is implemented to provide a laminar flow of a fluid, e.g., a gas or liquid, across a top surface of the optical head 53 . (The top surface can be a top surface of a lens included in the optical head 53 .) The laminar flow of fluid across the top surface of the optical head 53 can sweep opaque slurry out of the optical access and/or prevent slurry from drying on the top surface and, consequently, improves transmission through the optical access. With implementations in which the polishing pad 30 includes a solid window instead of an aperture, the flushing system is implemented to direct a flow of gas at a bottom surface of the window. The flow of gas can prevent condensation from forming at the solid window's bottom surface which would otherwise impede optical access. FIG. 3 shows an implementation of the laminar-flow flushing system. The flushing system includes a gas source 302 , a delivery line 304 , a delivery nozzle 306 , a suction nozzle 308 , a vacuum line 310 , and a vacuum source 312 . The gas source 302 and vacuum source can be configured so that they can introduce and suction a same or a similar volume of gas. The delivery nozzle 306 is situated so that the laminar flow of gas is directed across the transparent top surface 314 of the in-situ monitoring module and not directed at the substrate surface being polished. Consequently, the laminar flow of gas does not dry out slurry on a substrate surface being polished, which can undesirably affect polishing. FIG. 4 shows an implementation of the flushing system for preventing the formation of condensation on a bottom surface of the solid window. The system reduces or prevents the formation of condensation at the bottom surface of the polishing pad window. The system includes a gas source 402 , a delivery line 404 , a delivery nozzle 406 , a suction nozzle 408 , a vacuum line 410 , and a vacuum source 412 . The gas source 402 and vacuum source can be configured so that they can introduce and suction a same or a similar volume of gas. The delivery nozzle 406 is situated so that the flow of gas is directed at the bottom surface window in the polishing pad 30 . In one implementation that is an alternative to the implementation of FIG. 4 , the flushing system does not include a vacuum source or line. In lieu of these components, the flushing system includes a vent formed in the platen so that the gas introduced into the space underneath the solid window can be exhausted to a side of the platen or, alternatively, to any other location in the polishing apparatus that can tolerate moisture. The above described gas source and vacuum source can be located away from the platen so that they do not rotate with the platen. In this case, a rotational coupler for convey gas is included each of the supply line and the vacuum line. Returning to FIG. 1 , the polishing apparatus 20 includes a combined slurry/rinse arm 39 . During polishing, the arm 39 is operable to dispense slurry 38 containing a liquid and a pH adjuster. Alternative, the polishing apparatus includes a slurry port operable to dispense slurry onto polishing pad 30 . The polishing apparatus 20 includes a carrier head 70 operable to hold the substrate 10 against the polishing pad 30 . The carrier head 70 is suspended from a support structure 72 , for example, a carousel, and is connected by a carrier drive shaft 74 to a carrier head rotation motor 76 so that the carrier head can rotate about an axis 71 . In addition, the carrier head 70 can oscillate laterally in a radial slot formed in the support structure 72 . In operation, the platen is rotated about its central axis 25 , and the carrier head is rotated about its central axis 71 and translated laterally across the top surface of the polishing pad. The polishing apparatus also includes an optical monitoring system, which can be used to determine a polishing endpoint as discussed below. The optical monitoring system includes a light source 51 and a light detector 52 . Light passes from the light source 51 , through the optical access 36 in the polishing pad 30 , impinges and is reflected from the substrate 10 back through the optical access 36 , and travels to the light detector 52 . A bifurcated optical cable 54 can be used to transmit the light from the light source 51 to the optical access 36 and back from the optical access 36 to the light detector 52 . The bifurcated optical cable 54 can include a “trunk” 55 and two “branches” 56 and 58 . As mentioned above, the platen 24 includes the recess 26 , in which the optical head 53 is situated. The optical head 53 holds one end of the trunk 55 of the bifurcated fiber cable 54 , which is configured to convey light to and from a substrate surface being polished. The optical head 53 can include one or more lenses or a window overlying the end of the bifurcated fiber cable 54 (e.g., as shown in FIG. 3 ). Alternatively, the optical head 53 can merely hold the end of the trunk 55 adjacent the solid window in the polishing pad. The optical head 53 can hold the above-described nozzles of the flushing system. The optical head 53 can be removed from the recess 26 as required, for example, to effect preventive or corrective maintenance. The platen includes a removable in-situ monitoring module 50 . The in-situ monitoring module 50 can include one or more of the following: the light source 51 , the light detector 52 , and circuitry for sending and receiving signals to and from the light source 51 and light detector 52 . For example, the output of the detector 52 can be a digital electronic signal that passes through a rotary coupler, e.g., a slip ring, in the drive shaft 22 to the controller for the optical monitoring system. Similarly, the light source can be turned on or off in response to control commands in digital electronic signals that pass from the controller through the rotary coupler to the module 50 . The in-situ monitoring module can also hold the respective ends of the branch portions 56 and 58 of the bifurcated optical fiber 54 . The light source is operable to transmit light, which is conveyed through the branch 56 and out the end of the trunk 55 located in the optical head 53 , and which impinges on a substrate being polished. Light reflected from the substrate is received at the end of the trunk 55 located in the optical head 53 and conveyed through the branch 58 to the light detector 52 . In one implementation, the bifurcated fiber cable 54 is a bundle of optical fibers. The bundle includes a first group of optical fibers and a second group of optical fibers. An optical fiber in the first group is connected to convey light from the light source 51 to a substrate surface being polished. An optical fiber in the second group is connected to received light reflecting from the substrate surface being polished and convey the received light to a light detector. The optical fibers can be arranged so that the optical fibers in the second group form an X-like shape that is centered on the longitudinal axis of the bifurcated optical fiber 54 (as viewed in a cross section of the bifurcated fiber cable 54 ). Alternatively, other arrangements can be implemented. For example, the optical fibers in the second group can form V-like shapes that are mirror images of each other. A suitable bifurcated optical fiber is available from Verity Instruments, Inc. of Carrollton, Tex. There is usually an optimal distance between the polishing pad window and the end of the trunk 55 of bifurcated fiber cable 54 proximate to the polishing pad window. The distance can be empirically determined and is affected by, for example, the reflectivity of the window, the shape of the light beam emitted from the bifurcated fiber cable, and the distance to the substrate being monitored. In one implementation, the bifurcated fiber cable is situated so that the end proximate to the window is as close as possible to the bottom of the window without actually touching the window. With this implementation, the polishing apparatus 20 can include a mechanism, e.g., as part of the optical head 53 , that is operable to adjust the distance between the end of the bifurcated fiber cable 54 and the bottom surface of the polishing pad window. Alternatively, the proximate end of the bifurcated fiber cable is embedded in the window. The light source 51 is operable to emit white light. In one implementation, the white light emitted includes light having wavelengths of 200-800 nanometers. A suitable light source is a xenon lamp or a xenon-mercury lamp. The light detector 52 can be a spectrometer. A spectrometer is basically an optical instrument for measuring properties of light, for example, intensity, over a portion of the electromagnetic spectrum. A suitable spectrometer is a grating spectrometer. Typical output for a spectrometer is the intensity of the light as a function of wavelength. Optionally, the in-situ monitoring module 50 can include other sensor elements. The in-situ monitoring module 50 can include, for example, eddy current sensors, lasers, light emitting diodes, and photodetectors. With implementations in which the in-situ monitoring module 50 includes eddy current sensors, the module 50 is usually situated so that a substrate being polished is within working range of the eddy current sensors. The light source 51 and light detector 52 are connected to a computing device operable to control their operation and to receive their signals. The computing device can include a microprocessor situated near the polishing apparatus, e.g., a personal computer. With respect to control, the computing device can, for example, synchronize activation of the light source 51 with the rotation of the platen 24 . As shown in FIG. 5 , the computer can cause the light source 51 to emit a series of flashes starting just before and ending just after the substrate 10 passes over the in-situ monitoring module. (Each of points 501 - 511 depicted represents a location where light from the in-situ monitoring module impinged and reflected off.) Alternatively, the computer can cause the light source 51 to emit light continuously starting just before and ending just after the substrate 10 passes over the in-situ monitoring module. With respect to receiving signals, the computing device can receive, for example, a signal that carries information describing a spectrum of the light received by the light detector 52 . FIG. 6A shows examples of a spectrum measured from light that is emitted from a single flash of the light source and that is reflected from the substrate. Spectrum 602 is measured from light reflected from a product substrate. Spectrum 604 is measured from light reflected from a base silicon substrate (which is a wafer that has only a silicon layer). Spectrum 606 is from light received by the optical head 53 when there is no substrate situated over the optical head 53 . Under this condition, referred to in the present specification as a dark condition, the received light is typically ambient light. The computing device can process the above-described signal to determine an endpoint of a polishing step. Without being limited to any particular theory, the spectra of light reflected from the substrate 10 evolve as polishing progresses. FIG. 6B provides an example of the evolution as polishing of a film of interest progresses. The different lines of spectrum represent different times in the polishing. As can be seen, properties of the spectrum of the reflected light changes as a thickness of the film changes, and particular spectrums are exhibited by particular thicknesses of the film. The computing device can execute logic that determines, based on one or more of the spectra, when an endpoint has been reached. The one or more spectra on which an endpoint determination is based can include a target spectrum, a reference spectrum, or both. As used in the instant specification, a target spectrum refers to a spectrum exhibited by the white light reflecting from a film of interest when the film of interest has a target thickness. By way of example, a target thickness can be 1, 2, or 3 microns. Alternatively, the target thickness can be zero, for example, when the film of interest is cleared so that an underlying film is exposed. FIG. 7A shows a method 700 for obtaining a target spectrum. Properties of a substrate with the same pattern as the product substrate are measured (step 702 ). The substrate which is measured is referred to in the instant specification as a “set-up” substrate. The set-up substrate can simply be a substrate which is similar or the same to the product substrate, or the set-up substrate could be one substrate from a batch. The properties can include a pre-polished thickness of a film of interest at a particular location of interest on the substrate. Typically, the thicknesses at multiple locations are measured. The locations are usually selected so that a same type of die feature is measured for each location. Measurement can be performed at a metrology station. The set-up substrate is polished in accordance with a polishing step of interest and spectra of white light reflecting off a substrate surface being polished are collected during polishing (step 704 ). Polishing and spectra collection can be performed at the above described polishing apparatus. Spectra are collected by the in-situ monitoring system during polishing. The substrate is overpolished, i.e., polished past an estimated endpoint, so that the spectrum of the light that reflected from the substrate when the target thickness is achieved can be obtained. Properties of the overpolished substrate are measured (step 706 ). The properties include post-polished thicknesses of the film of interest at the particular location or locations used for the pre-polish measurement. The measured thicknesses and the collected spectra are used to select, from among the collected spectra, a spectrum determined to be exhibited by a thickness of interest (step 708 ). In particular, linear interpolation can be performed using the measured pre-polish film thickness and post-polish substrate thicknesses to determine which of the spectra was exhibited when the target film thickness was achieved. The spectrum determined to be the one exhibited when the target thickness was achieved is designated to be the target spectrum for the batch of substrates. Optionally, the spectra collected are processed to enhance accuracy and/or precision. The spectra can be processed, for example: to normalize them to a common reference, to average them, and/or to filter noise from them. Particular implementations of these processing operations are described below. As used in the instant specification, a reference spectrum refers to a spectrum that is associated with a target film thickness. A reference spectrum is usually empirically selected for particular endpoint determination logic so that the target thickness is achieved when the computer device calls endpoint by applying the particular spectrum-based endpoint logic. The reference spectrum can be iteratively selected, as will be described below in reference to FIG. 7B . The reference spectrum is usually not the target spectrum. Rather, the reference spectrum is usually the spectrum of the light reflected from the substrate when the film of interest has a thickness greater than the target thickness. FIG. 7B shows a method 701 for selecting a reference spectrum for a particular target thickness and particular spectrum-based endpoint determination logic. A set up substrate is measured and polished as described above in steps 702 - 706 (step 703 ). In particular, spectra collected and the time at which each collected spectrum is measured is stored. A polishing rate of the polishing apparatus for the particular set-up substrate is calculated (step 705 ). The average polishing rate PR can be calculated by using the pre and post-polished thicknesses T 1 , T 2 , and the actual polish time, PT, e.g., PR=(T 2 −T 1 )/PT. An endpoint time is calculated for the particular set-up substrate to provide a calibration point to test the reference spectrum, as discussed below (step 707 ). The endpoint time can be calculated based on the calculated polish rate PR, the pre-polish starting thickness of the film of interest, ST, and the target thickness of the film of interest, TT. The endpoint time can be calculated as a simple linear interpolation, assuming that the polishing rate is constant through the polishing process, e.g., ET=(ST−TT)/PR. Optionally, the calculated endpoint time can be evaluated by polishing another substrate of the batch of patterned substrates, stopping polishing at the calculated endpoint time, and measuring the thickness of the film of interest. If the thickness is within a satisfactory range of the target thickness, then the calculated endpoint time is satisfactory. Otherwise, the calculated endpoint time can be re-calculated. One of the collected spectra is selected and designated to be the reference spectrum (step 709 ). The spectrum selected is a spectrum of light reflected from the substrate when the film of interest has a thickness greater than and is approximately equal to the target thickness. The particular endpoint determination logic is executed in simulation using the spectra collected for the set-up substrate and with the selected spectrum designated to be the reference spectrum (step 711 ). Execution of the logic yields an empirically derived but simulated endpoint time that the logic has determined to be the endpoint. The empirically derived but simulated endpoint time is compared to the calculated endpoint time (step 713 ). If the empirically derived endpoint time is within a threshold range of the calculated endpoint time, then the currently selected reference spectrum is known to generate a result that matches the calibration point. Thus, when the endpoint logic is executed using the reference spectrum in a run-time environment, the system should reliably detect an endpoint at the target thickness. Therefore, the reference spectrum can be kept as the reference spectrum for run time polishing of the other substrates of the batch (step 718 ). Otherwise, steps 709 and 711 are repeated as appropriate. Optionally, variables other than the selected spectrum can be changed for each iteration (i.e., each performance of steps 709 and 711 ). For example, the above-mentioned processing of the spectra (for example, filter parameters) and/or a threshold range from a minimum of a difference trace can be changed. The difference trace and the threshold range of a minimum of the difference trace are described below. FIG. 8A shows a method 800 for using spectrum-based endpoint determination logic to determine an endpoint of a polishing step. Another substrate of the batch of patterned substrates is polished using the above-described polishing apparatus (step 802 ). At each revolution of the platen, the following steps are performed. One or more spectra of white light reflecting off a substrate surface being polished are measured to obtain one or more current spectra for a current platen revolution (step 804 ). The one or more spectra measured for the current platen revolution are optionally processed to enhance accuracy and/or precision as described above in reference to FIG. 7A and as described below in reference to FIG. 11 . If only one spectrum is measured, then the one spectrum is used as the current spectrum. If more than one current spectra is measured for a platen revolution, then they are grouped, averaged within each group, and the averages are designated to be current spectra. The spectra can be grouped by radial distance from the center of the substrate. By way of example, a first current spectrum can be obtained from spectra measured as points 502 and 510 ( FIG. 5 ), a second current spectrum can be obtained from spectra measured at points 503 and 509 , a third current spectra can be obtained from spectra measured at points 504 and 508 , and so forth. The spectra measured at points 502 and 510 are averaged to obtain a first current spectrum for the current platen revolution. The spectra measured at points 503 and 509 are averaged to obtain a second current spectrum for the current platen revolution. The spectra measured at points 504 and 508 are averaged to obtain a third current spectrum for the current platen revolution. A difference between the one or more current spectra and a reference spectrum is calculated (step 806 ). The reference spectrum can be obtained as described above in reference to FIG. 7B . In one implementation, the difference is a sum of differences in intensities over a range of wavelengths. That is, Difference = ∑ λ = a b ⁢ ⁢ abs ⁡ ( I current ⁢ ⁡ ( λ ) - I reference ⁡ ( λ ) ) where a and b are the lower limit and upper limit of the range of wavelengths of a spectrum, respectively, and I current (λ) and I reference (λ) are the intensity of a current spectra and the intensity of the target spectra for a given wavelength, respectively. Each calculated difference is appended to a difference trace (step 808 ). The difference trace is generally a plot of the calculated difference. The difference trace is updated at least once per platen revolution. (When multiple current spectra are obtained for each platen revolution, the difference trace can be updated more than once per platen revolution.) Optionally, the difference trace can be processed, for example, smoothing the difference trace by filtering out a calculated difference that deviates beyond a threshold from preceding one or more calculated differences. Whether the difference trace is within a threshold value of a minimum is determined (step 810 ). After the minimum has been detected, the endpoint is called when the different trace begins to rise past a particular threshold value of the minimum. Alternatively, the endpoint can be called based on the slope of the difference trace. In particular, the slope of the difference trace approaches and becomes zero at the minimum of the difference trace. The endpoint can be called when the slope of the difference trace is within a threshold range of the slope that is near zero. Optionally, window logic can be applied to facilitate the determination of step 808 . Window logic suitable for use is described in commonly assigned U.S. Pat. Nos. 5,893,796 and 6,296,548, which are incorporated by reference. If the difference trace is NOT determined to have reached a threshold range of a minimum, polishing is allowed to continue and steps 804 , 806 , 808 , and 810 are repeated as appropriate. Otherwise, an endpoint is called and polishing is stopped (step 812 ). FIG. 8B illustrates the above described method for determining endpoint. Trace 801 is the raw difference trace. Trace 803 is the smoothed difference trace. Endpoint is called when the smoothed difference trace 803 reaches a threshold value 805 above the minimum 807 . As an alternative to using a reference spectrum, a target spectrum can be used in the method 800 . The difference calculation would be between a current spectrum and the target spectrum, and endpoint would be determined when the difference trace reaches a minimum. FIG. 9A shows an alterative method 900 for using a spectrum-based endpoint determination logic to determine an endpoint of a polishing step. A set-up substrate is polished and a target spectrum and reference spectrum are obtained (step 902 ). These spectra can be obtained as described above in reference to FIGS. 7A and 7B . A target difference is calculated (step 904 ). The target difference is the difference between the reference spectrum and the target spectrum and can be calculated using the above-described difference equation. Polishing of another substrate of the batch of substrates is started (step 906 ). The following steps are performed for each platen revolution during polishing. One or more spectra of white light reflecting off a substrate surface being polished are measured to obtain one or more current spectra for a current platen revolution (step 908 ). A difference between the current one or more spectra and the reference spectrum is calculated (step 910 ). The calculated difference or differences (if there are more than one current spectrum) are appended to a difference trace (step 912 ). Whether the difference trace is within a threshold range of the target difference is determined (step 914 ). If the difference trace is NOT determined to have reached a threshold range of the target difference, polishing is allowed to continue and steps 908 , 910 , 912 , and 914 are repeated as appropriate. Otherwise, an endpoint is called and polishing is stopped (step 916 ). FIG. 9B illustrates the above described method for determining endpoint. Trace 901 is the raw difference trace. Trace 903 is the smoothed difference trace. Endpoint is called when the smooth difference trace 903 is within a threshold range 905 of a target difference 907 . FIG. 10A shows another method 1000 for determining an endpoint of a polishing step. A reference spectrum is obtained (step 1002 ). The reference spectrum is obtained as described above in reference to FIG. 7B . The spectra collected from the process of obtaining the reference spectrum are stored in a library (step 1004 ). Alternatively, the library can include spectra that are not collected but theoretically generated. The spectra, including the reference spectrum, are indexed so that each spectrum has a unique index value. The library can be implemented in memory of the computing device of the polishing apparatus. A substrate from the batch of substrates is polished, and the following steps are performed for each platen revolution. One or more spectra are measured to obtain a current spectra for a current platen revolution (step 1006 ). The spectra are obtained as described above. The spectra stored in the library which best fits the current spectra is determined (step 1008 ). The index of the library spectrum determined to best fits the current spectra is appended to an endpoint index trace (step 1010 ). Endpoint is called when the endpoint trace reaches the index of the reference spectrum (step 1012 ). FIG. 10B illustrates the above described method for determining endpoint. Trace 1014 is the raw index trace. Trace 1016 is the smoothed difference trace. Line 1018 represents the index value of the reference spectrum. Multiple current spectra can be obtained in each sweep of the optical head beneath the substrate, e.g., a spectra for each radial zone on the substrate being tracked, and an index trace can be generated for each radial zone. FIG. 11 shows an implementation for determining an endpoint during a polishing step. For each platen revolution, the following steps are performed. Multiple raw spectra of white light reflecting off a substrate surface being polished are measured (step 1102 ). Each measured raw spectra is normalized to remove light reflections contributed by mediums other than the film or films of interest (step 1104 ). Normalization of spectra facilitates their comparison to each other. Light reflections contributed by media other than the film or films of interest include light reflections from the polishing pad window and from the base silicon layer of the substrate. Contributions from the window can be estimated by measuring the spectrum of light received by the in-situ monitoring system under a dark condition (i.e., when no substrates are placed over the in-situ monitoring system). Contributions from the silicon layer can be estimated by measuring the spectrum of light reflecting of a bare silicon substrate. The contributions are usually obtained prior to commencement of the polishing step. A measured raw spectrum is normalized as follows: normalized spectrum=( A −Dark)/( Si −Dark) where A is the raw spectrum, Dark is the spectrum obtained under the dark condition, and Si is the spectrum obtained from the bare silicon substrate. Optionally, the collected spectra can be sorted based on the region of the pattern that has generated the spectrum, and spectra from some regions can be excluded from the endpoint calculation. In particular, spectra that are from light reflecting off scribe lines can be removed from consideration (step 1106 ). Different regions of a pattern substrate usually yield different spectra (even when the spectra were obtained at a same point of time during polishing). For example, a spectrum of the light reflecting off a scribe line in a substrate is different from the spectrum of the light reflecting off an array of the substrate. Because of their different shapes, use of spectra from both regions of the pattern usually introduces error into the endpoint determination. However, the spectra can be sorted based on their shapes into a group for scribe lines and a group for arrays. Because there is often greater variation in the spectra for scribe lines, usually these spectra can be excluded from consideration to enhance precision. A subset of the spectra processed thus far is selected and averaged (step 1108 ). The subset consists of the spectra obtained from light reflecting off the substrate at points of a region on the substrate. The region can be, for example, region 512 or region 413 ( FIG. 5 ). Optionally, a high-pass filter is applied to the measured raw spectra (step 1110 ). Application of the high pass filter typically removes low frequency distortion of the average of the subset of spectra. The high-pass filter can be applied to the raw spectra, their average, or to both the raw spectra and their average. The average is normalized so that its amplitude is the same or similar to the amplitude of the reference spectrum (step 1112 ). The amplitude of a spectrum is the peak-to-trough value of the spectrum. Alternatively, the average is normalized so that its reference spectrum is the same or similar to a reference amplitude to which the reference spectrum has also been normalized. A difference between the normalized average and a reference spectrum is calculated (step 1114 ). The reference spectrum is obtained as described in reference to FIG. 7B . The difference is calculated using the above-described equation for calculating differences between spectra. A difference trace is updated with the current difference (step 1116 ). The difference trace exhibits calculated differences between normalized averages and the reference spectrum as a function of time (or platen revolution). A median and low-pass filter is applied to the updated difference trace (step 1118 ). Application of these filters typically smoothes the trace (by reducing or eliminating spikes in the trace). Endpoint determination is performed based on the updated and filtered difference trace (step 1120 ). The determination is made based on when the difference trace reaches a minimum. The above described window logic is used to make the determination. More generally, the signal processing steps of steps 1104 - 1112 can be used to improve endpoint determination procedures. For example, instead of generation of a difference trace, the normalized average spectra could be used to select a spectra from a library to generate an index trace, as described above in reference to FIG. 10A . FIG. 12 illustrates the normalization of step 1112 . As can be seen, only a portion of a spectrum (or an average of spectra) is considered for normalization. The portion considered is referred to in the instant specification as a normalization range and, furthermore, can be user selectable. Normalization is effected so that the highest point and the lowest point in the normalization range are normalized to 1 and 0, respectively. The normalization is calculated as follows: g =(1−0)/( r max −r min ) h =1 −r max ·g N=R·g+h where, g is a gain, h is an offset, r max is the highest value in the normalization range, r min is the lowest value in the normalization range, N is the normalized spectrum, and R is the pre normalized spectrum. Embodiments of the invention and all of the functional operations described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structural means disclosed in this specification and structural equivalents thereof, or in combinations of them. Embodiments of the invention can be implemented as one or more computer program products, i.e., one or more computer programs tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, data processing apparatus, e.g., a programmable processor, a computer, or multiple processors or computers. A computer program (also known as a program, software, software application, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file. A program can be stored in a portion of a file that holds other programs or data, in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub-programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network. The processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). The above described polishing apparatus and methods can be applied in a variety of polishing systems. Either the polishing pad, or the carrier head, or both can move to provide relative motion between the polishing surface and the substrate. For example, the platen may orbit rather than rotate. The polishing pad can be a circular (or some other shape) pad secured to the platen. Some aspects of the endpoint detection system may be applicable to linear polishing systems, e.g., where the polishing pad is a continuous or a reel-to-reel belt that moves linearly. The polishing layer can be a standard (for example, polyurethane with or without fillers) polishing material, a soft material, or a fixed-abrasive material. Terms of relative positioning are used; it should be understood that the polishing surface and substrate can be held in a vertical orientation or some other orientation. Particular embodiments of the invention have been described. Other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results.

Methods and apparatus for providing a chemical mechanical polishing pad. The pad includes a polishing layer having a top surface and a bottom surface. The pad includes an aperture having a first opening in the top surface and a second opening in the bottom surface. The top surface is a polishing surface. The pad includes a window that includes a first portion made of soft plastic and a crystalline or glass like second portion. The window is transparent to white light. The window is situated in the aperture so that the first portion plugs the aperture and the second portion is on a bottom side of the first portion, wherein the first portion acts a slurry-tight barrier.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for calculating, storing and displaying the score of a competitive sport or game that is similar to tennis. 2. Description of the Prior Art In any competitive game, it is of great value to keep a reliable record of scores as the game progresses. In games that are generally regarded as spectator sports, it is often worthwhile for owners of the playing facilities to invest in large scoreboards so that the results and timing of a game are immediately visible to spectators, players and officials alike. But many sports are played only in the presence of the players, and costly scoreboard arrangements are not economically feasible. Some games, such as tennis, lawn tennis, table tennis and volleyball have scoring systems that are not as straightforward as simply counting a point score until a particular value is reached. In each of the games cited, there is at some point in the game a condition in which a player must achieve a certain number of points greater than those of his opponent in order to win and terminate the game. The two conditions described above indicate a need for a device which may be used without costly construction, without hindering the physical activities of the players, and with the ability to construct a score sequence that goes beyond ordinary point counting. U.S. Pat. No. 3,254,433 to Saile and Saile describes a partial but useful approach to these problems, wherein a scoring device mountable on the fence of a tennis court contains an actuating mechanism on its front panel, which indexes a score displaying mechanism whenever a tennis ball is thrown at it. This allows the scores to be displayed without requiring either player to carry a bulky scorekeeping device, and without participation by any third party. It does not, however, teach means for identifying and calculating the existence of a "deuce" or "advantage" condition as is frequent in tennis; such a condition may be displayed, but requires the player to strike the target panel more than once to position the display device to the proper score. A comprehensive solution to the needs of scoring a game such as tennis would necessarily involve a device that may be adapted for either public display (as in a scoreboard), or which may be small and light enough for the player to wear without discomfort or restriction of his playing skill. It should also respond to any new point scored in tennis or similar games without requiring the player to divert his consciousness from the actual playing of the game, and hence should be fully automatic in its calculation of a new score, as well as in its ability to identify the winning of a game and the subsequent increase in a player's set score. In addition to the scoring of games, there are other features which are incidental to the playing of a game and which would render such a device much more useful, explicitly to the tennis player. Some games including tennis require the exchange of sides of the playing court after a certain number of games are played, to insure fairness in the presence of local playing conditions such as sunlight or wind. Accordingly, it is an object of the present invention to provide a court change indication based on a particular class of scoring states. When several players must share the same facilities, local rules frequently provide for a particular time limit for playing. Accordingly, it is an object of the present invention to provide an indication of a preset elapsed time, and to provide for the possible indication of time of day or elapsed time. U.S. Pat. Nos. 3,928,960 and 3,803,834, both to Reese, disclose conventional arithmetic calculators in combination with a time-of-day indication, but do not teach the application of game scoring in their respective calculator functions. SUMMARY OF THE INVENTION The present invention is applied to an electronic calculator for scoring of tennis and similar games in which winning of a game requires one opponent's score to be a specific number of points greater than the score of the other opponent. To avoid the use of point-counting registers of infinite or impractically large numeric capacity, the present invention allows either score to reach a maximum value, and thereafter operates to decrement the opponent's score until a condition is reached in which the winning of a new point results in the winning of a game. Means are provided to clear an incorrect entry and return to the previous, valid score values. For games in which the achievement of a particular set of point values changes the method of declaring scores, as for example the use of "deuce" or "advantage" scores in tennis, display means and display encoder circuitry are provided to recognize such an endgame condition and to display the scores as required. Additional means are provided to count and display the number of games won for each opponent, to derive and display a court-change indication based on the number of games played, and to derive and indicate the passage of a particular time limit, as is often required when players are using shared facilities. The present invention makes use of logic circuitry which may be packaged as medium--or large-scale integrated circuits, so that it may be small and light enough for the players to wear on a belt, or in a configuration similar to a wristwatch, or in combination with an electronic wristwatch with shared or separate displays and controls. These and other features, objects and advantages of the present invention will become apparent to those skilled in the art from a consideration of the following detailed description of a preferred embodiment of the invention, taken in conjunction with the appended drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a drawing of a control and display panel for actuation of the present invention and for display of the results; and FIG. 2 is a block diagram showing a preferred partitioning of circuit modules within the present invention; and FIG. 3 is a logic diagram of data entry keys and associated circuitry of the preferred embodiment; and associated circuitry of the preferred embodiment; and FIG. 4 is a block diagram of memory means for deriving and storing score results, and FIG. 5 is a logic diagram of counter means for deriving and storing score results; and FIG. 6 is a logic diagram for circuitry common to the scoring for two players for use with the counter means of FIG. 5; and FIG. 7 is a logic diagram of a display decoder and game score display means of the present invention; and FIG. 8 is a logic diagram of circuitry for calculating and displaying set score of the present invention; and FIG. 9 is a logic diagram of circuits common to the set score calculation and display for two players. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, there is shown one of many possible layouts of a control and display panel for activating the present invention, and for viewing the results of its calculations. A switch 10 applies power from a suitable storage cell or similar power source. A CLEAR key 11 causes all scores to be effectively set to zero, and all internal status registers to be reset to an appropriate inital value. A pair of point-entry keys 12 causes the score of each of two players to be incremented, and a CLEAR ENTRY key 13 reverses the process in the event of an incorrect entry by the user. Game displays 14 and 15 show the current value of each player's score in a format that is suitable for the game being played. So that the calculator may be capable of accumulating the number of individual games won by each player, there is included one set score display 16 for each player. The set display 16 may additionally be capable of blinking for a period of time after a new game has been won, as an auxiliary means for indicating which of the two players has won the most recently completed game. A court change indicator 17 may be included to indicate that the players must change courts, or perform another action which is based on alternate games completed. In tennis, the court change indicator is configured to light whenever the sum of the set scores is an odd number, i.e., after every other game. An additional indicator, not shown in FIG. 1, may be a COURT TIME ALARM, which may be a visible indicator or an audible alarm, and whose purpose is to remind the players that a specified period of time has passed since their period of play began. In tennis, for example, a one-hour time limit is typical for the use of shared courts. As a means to facilitate the use and interpretation of results of scoring, both the data entry keys 12 and the score indicators 15 and 16 may be compatibly color coded so that the user has an immediate and clear idea of which keys to press and of which scores are associated with which keys. Referring now to FIG. 2, there is shown the perferred embodiment of the present invention, in the form of a block diagram. It will be understood that lines representing signal flow between and among the different modules is for illustrative purposes, and that a wide variety of partitioning modes is possible, within the constraints of the matter disclosed herein. A KEY ENCODER AND STROBE GENERATOR 20 contains the function keys 11, 12 and 13 of FIG. 1, and additionally contains storage registers, logic and strobe-generation circuitry to provide appropriate command signals to the remainder of the circuits and displays. A GAME STATUS REGISTER AND LOGIC 21 contains registers and logic that are commonly required to calculate and display the game scores of both players. GAME SCORE REGISTERS AND LOGIC 22 are duplicated identically for each player and contain a counting register appropriate to the game being scored, in conjunction with logic to cause each player's score to be changed as each successive point is scored, or as a scored point is withdrawn via the CLEAR ENTRY key 13 of FIG. 1. Because it is advisable from the standpoint of keeping circuitry to a practical minimum, certain functions are created in one of the GAME SCORE REGISTERS AND LOGIC 22, and used as an input in the opponent's corresponding logic. Hence, the data flow is shown as running in both directions between the GAME STATUS REGISTER 21 and the GAME SCORE REGISTER 22. Based on the logical signals derived in 22 and elsewhere within the calculator, a GAME ENCODER AND DISPLAY 23 encodes the resulting score into display format for each player and presents it on a pair of conventional seven-segment display devices shown as 14 and 15 in FIG. 1. The essential functions of both the game and set score calculating modules are twofold: to store a digital representation of the current score in each case, and to replace that score with a new one on command, based on a logical combination of the current score and the input keys being actuated. Because there are many conventions associated with logic design, and many design choices that may be passed on economy or availability of components but are otherwise arbitrary, it will be understood that a variety of different combinations of data registers and logic elements may be constructed without departing from the inventive concept disclosed herein. Referring now to FIG. 3, there is shown preferred means for decoding keystrokes and generating strobe and control signals to actuate the remainder of the circuitry of the invention. The key switches 11, 12 and 13 are drawn as the electrical equivalent of those of FIG. 1, and in the preferred embodiment will create a low logic level whenever each key is depressed. It will be recalled that the actual polarities of these resultant logic signals, as well as all the remaining signals disclosed herein, are totally arbitrary and may be exchanged at will, provided that they remain logically compatible with the signals which will be used in combination with them. Upon depression of the ENTER A switch 12a or the ENTER B switch 12b, a register 30, also known as a flip-flop or a bistable latch, will be set to a state corresponding to output signals POINT A or POINT B, respectively, as an indication of which player is to receive the new point. At approximately the same time, an OR gate 32 generates a pulse meaning that either one of the ENTER switches 12 has been depressed. This pulse sets another register 31, as an indication that the last action was a SCORE as opposed to a CLEAR ENTRY condition. If either a SCORE or a CLEAR ENTRY action has taken place, a monostable multivibrator or triggering device 35 generates a pulse called STROBE upon release of the key in question. To prevent multiple triggering of the CLEAR ENTRY function, it is desirable to provide an INHIBIT function to the triggering device 35, whose logic state is derived from the CLEAR ENTRY signal and the logical inverse of the SCORE signal, as combined in the AND gate 34. It will be observed that all references to AND gates and OR gates will be construed to include corresponding inverted functions such as NAND and NOR, and that a small circle drawn at an input or output denotes a logic level inversion that is appropriate to the signals being acted upon within the preferred embodiment. Finally, depression of the CLEAR key 11 will generate a pulse of appropriate level to reset registers within the invention at the start of operation. This function may be performed automatically when power is first applied, as is common and well known in the art. As is also common, it is desirable to provide "pull-up" resistors to each keyswitch to firmly establish its inactive electrical state and prevent false triggering due to electrical noise. Although not shown on the drawings, each active circuit requires the application of electrical power, and grounds for power and signal. Recalling that two of the principal functions of the invention are to store each new score as it is calculated, and to derive the next score based on a logical combination of the previous score and the keyswitch last actuated, FIG. 4 illustrates one method for accomplishing these objectives. A data register or LATCH 41 is used to contain a representation of the last score derived. In the preferred embodiment, as applied to the game of tennis, the scores of two players are contained in two two-bit registers (A0, A1) and (B0, B1), where A and B refer to the respective players and the digits 0 and 1 refer to the lower-order and high-order binary digits respectively. The meaning of the digits with respect to ordinary scoring is simply a binary count of the points received; thus in tennis, register (A0, A1) would initially contain score representations according to the following table: ______________________________________ TENNIS SCORE A1 A0______________________________________ 0 (LOVE) 0 0 15 0 1 30 1 0 40 1 1______________________________________ In tennis and many other sports, however, there is a condition within a game where the numerical scoring as illustrated above is abandoned, and the scorekeepers switch to an alternate method based on points-ahead rather than the absolute number of points scored. The convention in tennis, for example, is to declare the score DEUCE or DEUCE GAME whenever the score is 40--40, and every time thereafter that the players have an identical number of points. When one player has a one-point lead, the score is declared ADVANTAGE or AD for that player, and a two-point lead constitutes the winning of GAME. To account for such a condition within the present invention, a single register has been provided within the LATCH 41 of FIG. 4, and its output state is called END. Thus for a complete game of tennis, all the scores possible may be represented by the following table: ______________________________________TENNISSCORE A1 A0 END______________________________________0(LOVE) 0 0 015 0 1 030 1 0 040(not DEUCE) 1 1 0DEUCE 1 1 1AD (player A) 1 1 1AD (player B) 1 0 1______________________________________ All that is required to calculate a subsequent score is to decode the combined logic states of the registers within the LATCH 41, comprising A0, A1, B0 and B1, in combination with the input logic states POINT A (which is always the logical inverse of POINT B) and whether or not the SCORE condition (as opposed to the CLEAR ENTRY condition) is being requested by the circuitry of FIG. 3. One method of accomplishing the decoding function is via the use of a NON-VOLATILE MEMORY 40, which may be any of a wide variety of memory products including a read-only memory or any form of magnetic core provided with non-destructive readout or a means for refreshing its contents after reading. The address of a particular memory location comprises the logic states of A0, A1, B0, B1, POINT A and SCORE presented in any order, and the contents of the memory location will be preset with the appropriate values of A0, A1, B0 and B1. The actual contents of such a memory table are not presented here because of their length, although one skilled in the art could easily construct such a table and pre-program the NON-VOLATILE MEMORY 40 to select new values for each score condition. Because of its utility in interpreting the resulting scores for display purposes, an additional output function END is shown in FIG. 4. It is not absolutely necessary to include this function, although it is preferable to render the required logic circuitry minimum that it be included in the outputs presented to LATCH 41. By reference to the latter of the two score tables above, it is observed that a DEUCE is represented by a TRUE bit in both registers A0 and A1. The same condition could just as effectively be represented by a TRUE in the A1 register and a FALSE in the A0 register for DEUCE, provided that A registers and the B registers both contained the same score, and means were provided to inform the display circuitry that the score being represented were a DEUCE as opposed to 30-30 or 40-40. The END logic state serves this function for use in display coding, and in the preferred embodiment it is also used to force the internal representation of a DEUCE score to 11 (binary) rather than 10, for purposes of reducing logic required to decode the score. Thus the END option is included as a latched output in FIG. 4. Still with reference to FIG. 4, the STROBE input generated within the circuitry of FIG. 3 or its functional equivalent is used to cause the MEMORY 40 to retrieve each new score, and the LATCH 41 to preserve the retrieved output. It will be understood that memory products with built-in latches for output are functionally and structurally equivalent to the combination of FIG. 4. Another embodiment of the score register and score encoder combination of the present invention is disclosed in FIGS. 5 and 6. Referring now to FIG. 5, a pair of registers 50 and 51 are shown as containing the score bits A1 and A0, respectively, it being understood that the entirety of the circuit in FIG. 15 is replicated for players A and B, identically. In the circuit of FIG. 5, the registers themseleves contain decoding inputs J and K and are commonly known as J-K flip-flops. Whenever a strobe is applied to the clocking input C of either, the resulting output state will transition to a new value depending upon the initial states of J and K, according to the following table: ______________________________________INITIAL VALUES OUTPUT J K Q______________________________________0 0 Same as prior output0 1 01 0 11 1 Opposite prior output______________________________________ It will be shown that the circuit of FIG. 5 can be made to function as an up-down counter which may be loaded to an initial state 01 (binary) or 00, to satisfy the scorekeeping requirements of the present invention. Whenever the STROBE is received, the AND gate 57 will allow that strobe to pass to registers 50 and 51 if the output of the EXCLUSIVE-OR gate 56 is high. The latter condition will be true whenever the POINT A input is TRUE, unless the EXCHANGE STROBES input is TRUE, in which case the gate 57 will pass the strobe only if POINT B (the inverse of POINT A) is in the TRUE state. As an example of the need to exchange the strobes in this fashion, it will be recalled that following a DEUCE score, it is desirable upon the winning of a point by player B to decrease player A's score register to binary 10 rather than increment player B's register, which would be interpreted by the display and set-score circuitry to denote the winning of a game. Whenever registers 50 and 51 receive a strobe from gate 57, they will assume a new state based on their respective J and K inputs. Referring to the truth table shown above, the registers 50 and 51 will increment their binary count under normal circumstances. With J0 and K0 both TRUE, the lower-order bit A0 will always change states, as it should for either an up--or down-count. If the special-condition inputs DOWN and FIRST are both in the FALSE state as they will be for usual operation, the value of J1 and K1 will both assume the value of A0 after their passage through gates 52, 53 and 54. This will mean that when the prior state of A0 is TRUE, A1 will change states, and when the prior state of A0 is FALSE, then A1 will not change states. Thus the binary up-count 00, 01, 10, 11, 00 . . . etc. is satisfied and the circuit functions as an up-counter. By presentation of the DOWN input signal, the sense of A0 is inverted as it passes through the EXCLUSIVE-OR gate 52, the binary sequence 11, 10, 01, 00, 11 . . . is satisfied and the circuit functions as a down-counter. Under special circumstances, the register comprising 50 and 51 will need to be loaded to an initial value. After a game has been won by one of the players, and when the next point has been scored, it is desirable to set the score of the winner of that point to binary 01, and that of the loser to binary 00. To accomplish this, the higher-order bits A1 and B1 are both set to zero by loading the J1 and K1 inputs of each register with 0 and 1 respectively. Existence of a TRUE state on input FIRST will force J1 to FALSE via the AND gate 53, and will force K1 to TRUE via the OR gate 54. To load the proper initial score into the lower-order bit of each register, the winner's J0 input will be FALSE due to AND gate 55 in the opponent's register. Consequently, the J-K inputs represented by binary 10 will render the winner's low-order register 1, and, by symmetry, the loser's corresponding register 0. Although the embodiment shown uses J-K flip-flops as the register and counting element, those skilled in the art will observe that there are other choices of register element. For example, a device commonly known as a D flip-flop will assume its input state upon receipt of a strobe, and it is easy for those skilled in the art to configure that logic gates to derive an appropriate D input rather than two J-K inputs for each one-bit register. In addition to the score-calculating functions, certain outputs of each individual rgeister are useful for display and other functions to be described below. Thus the AND gate 58 goes TRUE whenever both bits of the register are 0, and the AND gate 59 whenever they are both 1, creating outputs A00 and A11, respectively. The AND combination of A11 and POINT A is derived by gate 60 for use in detecting the winning of a new game. Referring now to FIG. 6, there is shown a circuit for providing the common logic signals that are used by both the individual score registers 22a and 22b of FIG. 2. The AND combination of A11 and B11 creates a DEUCE condition via gate 67, whose output is used to preset register 65 and render the END signal TRUE. The latter signal is needed for the display to distinguish between numerical scores 0-15-30-40, and the endgame scores DEUCE and AD. The same register 65 is cleared during a STROBE cycle by setting its J input to FALSE and permanently wiring its K input to TRUE. The J-K combination represented by binary 01 then forces the END output to FALSE. Similarly, to create the logic state NEW, which records the fact that a game has been completed and is awaiting a new point or a CLEAR ENTRY command, the register 66 has its J input set to TRUE by either (A11 AND A) or (B11 AND B) via the OR gate 69. The K input of the same register 66 is set to FALSE normally, but goes TRUE when its own output is TRUE, and is thus self-clearing. The possible state changes are thus TRUE (JK=10) and FALSE (JK=01). Under normal operation, JK=00, and no change takes place, i.e., the NEW output remains FALSE. The remaining input condition, JK=11, will reset the NEW state to FALSE just as JK=01. A system CLEAR will preset the NEW register 66 to TRUE and blank the displays. As with the individual registers, certain auxiliary logic signals are useful. SCORE•DEUCE will set the EXCHANGE output to TRUE and hence the DOWN output to TRUE unless the SCORE input is FALSE, via the action of AND gate 70 and EXCLUSIVE-OR gate 74. The same effect is derived via AND gate 71 by the values END•SCORE•GAME. The latter value is derived in OR gate 73. The combination NEW•SCORE creates the logic state FIRST, to signify the beginning of a new game. Finally, DEUCE+NEW is derived in OR gate 75 and inhibits display of the left digit of the score in ENABLE L. Referring now to FIG. 7, there is shown a circuit for decoding the game registers 50 and 51 of FIG. 5 and the auxiliary registers 65 and 66 of FIG. 6, plus their logical combinations and keyboard input signals, into a format suitable for display in a commonly available device such as a light-emitting diode (LED) or liquid crystal display (LCD) with seven segments. One of the principal features of the present invention is the encoding of a display of two or more digits using common circuitry, and the ability efficiently to create symbols for the DEUCE and ADVANTAGE conditions. In FIG. 7, conventional symbology has been used for the seven segment displays 14a and 15a, namely that lower-case letters a through g denote the seven segments individually as shown on reference FIG. 15a. The action of the decoder, as embodied in gates 80 through 90, is best understood by reference to the following logic table: ______________________________________DIGIT SEGMENT CONDITION______________________________________LEFT a = ##STR1## b = TRUE (always active) c = TRUE d = ##STR2## e = END f = -d · g g = ##STR3##RIGHT a = e (LEFT) b = g (LEFT) c = TRUE d = TRUE e = b f = a g = -e + END______________________________________ It will be understood that a TRUE condition on one of the display segments will cause the segment to become active, and will either illuminate or present a contrasting reflection, depending upon its construction. It is desirable to blank one or both the digits under some circumstances; each digit will become active for the following input conditions: LEFT: [ENABLE L•A0]+]ENABLE L•A1•A0 •END] RIGHT: NEW+[DISPLAY B0•END]. It will also be understood that the display circuitry is symmetrical for two players A and B, including the creation of DISPLAY A0 and DISPLAY B0 signals to be routed to the opponent's display encoder. The resulting encoded signals are shown to the right of FIG. 7, including the all-blank condition (new game or opponent's advantage), the scores 0, 15, 30 and 40, and the derived alphabetic scores Ad and d, the latter being logically identical to Ad but with the left digit blanked. It will be observed that due to equalities within the logic table, only seven active lines are required for output; this means that an encoder similar in construction to a conventional seven-segment numeric display encoder could be built or created from a programmable logic array (PLA). Referring now to FIG. 8, there is shown a preferred circuit for counting and displaying set scores, or the tally of games won. An up-down counter 103 is driven by the STROBE accompanying the player's own game score, and under normal operation will increment the set score whenever a new game is won, as identified by the logical input SET UP, to be described below. If a new game is followed by a CLEAR ENTRY, however, it is necessary to count down, and the combination of POINT A•SET DN accomplishes this via the AND gate 102. Counter 103 is in this preferred example a four-bit binary-coded decimal counter whose outputs SET A0 through SET A3 drive a BCD to seven-segment display encoder 104, such as is common in the art. The encoder 104 in turn drives a seven-segment numerical display device 16a, which creates the digits 0 through 9. A separate BLINK input causes the selected display to flash for a predetermined time interval after the winning game. The set score calculator and display of FIG. 8 is duplicated identically for players A and B, except for the naming of logic signals. Referring now to FIG. 9, there are shown preferred circuits for commonly creating the logic signals necessary to drive the individual set score registers. The logical ouput SET UP used in FIG. 8 is created by the AND gate 110 using SCORE and GAME as its inputs. Similarly, NOT SCORE and NEW are combined in AND gate 111 to create the output SET DN. EXCLUSIVE-OR gate 112 determines that the gross set scores are odd or even as represented by their low-order bits SET A0 and SET B0, and activates a COURT CHANGE INDICATOR 17, shown here as a LED indicator. Monostable timers 114, 116 and 117 act to flash the winner's set score display upon receipt of a trigger BLINK A or BLINK B from the individual set score registers. Timer 114, driven by OR gate 113, will start the flashing and keep it active for a period of time (approximately two seconds is preferred), and the timers 116 and 117 alternately turn the display on and off, via the output called BLINK, which is combined with the most recent point signal (POINT A of FIG. 8) to flash the appropriate display. Finally, timer 118 as set to start timing when power is applied to the entire device, and to activate a visual or aural alarm 119 after a preset time limit. For tennis, a one-hour time limit is frequently applied to the use of shared courts, and is preferred for the present embodiment. While a specific embodiment of the invention has been described, it will be realized by those skilled in the art that various changes may be made therein without departing from the spirit or intent of the inventive concept. Therefore, it is intended that the scope of the present invention be delimited only by the claims appended below.

An electronic device for calculating, storing and indicating the scores and related information for a game of tennis is described. The circuit provides for the special requirements of tennis and similar games by recognizing the existence of an endgame condition such as "deuce" in tennis and registering each new score as a function of the previous score and the point most recently won. Both up-down counters and decoders using non-volatile memory, including "read-only memory" (ROM) are disclosed for the point-calculation function, and a display encoder is described which efficiently provides for the display of alphanumeric scores, including "deuce" and "advantage" conditions. The invention includes features for indicating court change requirements, elapsed time, time of day, and display emphasis when a game is won. All score calculations are subject to a clear-entry feature to rectify operating error.

RELATED PATENT DATA [0001] This application claims priority to U.S. Provisional Patent Application Ser. No. 61/946,610, filed Feb. 28, 2014, entitled, “System and Method for Time Managing Loads in the Transport of Goods”, the entirety of which is hereby incorporated by reference. TECHNICAL FIELD [0002] This disclosure pertains to business-to-business (B2B) transactions. More particularly, this disclosure relates to apparatus and methods for managing the transportation of freight. BACKGROUND [0003] Techniques are known for scheduling loads for delivery on behalf of a customer using a carrier. Such scheduling typically involves collating of multiple independent communications from one or more of phone calls, emails, and facsimiles from one or more customer and/or carriers. Logistics capabilities have yet to minimize efforts in intermediating load delivery for customers by carriers. Therefore, there exists a need to improve temporal selection of a load to be delivered and a load to be scheduled for delivery by a carrier that is to be transported for a prospective transportation industry customer. SUMMARY OF THE INVENTION [0004] A system and method are provided for managing the transportation of freight between shippers, brokers, and carriers. Functional interaction between the shippers, brokers, and carriers is provided in a different manner than is currently implemented in a “bricks & mortar” business model. [0005] According to one aspect, a computer-implemented system of providing date and time selection to a client from a server is provided to enable temporal scheduling of a load to be transported for a prospective transportation industry customer. The system includes user information and instructions and a computer processor. The user information and instructions are stored in a computer memory at a host server. The computer processor accesses the memory at a host server to retrieve the user information and instructions and executes the instructions to perform steps including: presenting from the server to the client at a user interface one or more of a selectable date range and a time range for which the user provides a temporal-based requirement for picking up a customer load; enabling selection of one or more of a date range and a time range at a user interface of the client; receiving a selected one or more of the date range and the time range at the server from a user at the client; storing the received information into the database; associating the stored temporal data with a waypoint indicative of a cargo delivery destination desired by a customer; associating the stored waypoint to a load; and associating the attached load to the customer. [0006] According to another aspect, a method is provided for enabling date and time selection from a client through a server to enable temporal scheduling of a load to be transported for a prospective transportation industry customer. BRIEF DESCRIPTION OF THE DRAWINGS [0007] Preferred embodiments of the disclosure are described below with reference to the following accompanying drawings. [0008] FIG. 1 is a block diagram of the central processing system and network used to carry out temporal selection of a load to be delivered and a load to be scheduled for delivery by a carrier that is to be transported for a prospective transportation industry customer according to an exemplary embodiment. [0009] FIG. 2 illustrates a flowchart for implementing user authentication and permissions to access through one or more interfaces the features and functionality of FIG. 1 in accordance with an exemplary embodiment. [0010] FIG. 3 illustrates a flowchart for displaying load data to users and clients and for selecting and transmitting temporal data requirements for shipping the load. [0011] FIGS. 4A and 4B together illustrate a flowchart for a customer selecting carrier bids, approving carrier rates, accepting carrier bids, and storing multiple customer approved bids on a load. [0012] FIG. 5 illustrates a screen shot of a web page for a simple request for a broker for posting loads and identifying shippers and receivers of a type that would be displayed on the screen of one of the computers connected for communication with the processing circuitry of the server for the system of FIG. 1 . [0013] FIG. 6 illustrates a screen shot of a web page for a date/time/selection menu that pops up when a user selects a “Date & Time” field in one of the shipper and received fields of FIG. 5 . [0014] FIG. 7 illustrates a screen shot of a web page showing a user “mousing over” a selected date range field prior to selecting a time range. [0015] FIG. 8 illustrates a screen shot of a web page showing a selected temporal range achieved in FIG. 7 . [0016] FIG. 9 illustrates a screen shot of a web page showing selection of a receiver “Set Date & Time” field. [0017] FIG. 10 illustrates a screen shot of a web page showing a selected a temporal range for the pop-up menu of FIG. 6 . [0018] FIG. 11 illustrates a screen shot of a web page for realizing the temporal range selected in FIG. 10 . [0019] FIG. 12 illustrates a screen shot of a user login page. [0020] FIG. 13 illustrates a screen shot of a customer dashboard. [0021] FIG. 14 illustrates a screen shot showing customer load details. [0022] FIG. 15 illustrates a screen shot showing a customer new load. [0023] FIG. 16 illustrates load details including a new load with a temporal range selection. [0024] FIG. 17 illustrates a flowchart depicting account manager load interaction flow and privileges in accordance with an exemplary embodiment. [0025] FIGS. 18A and 18B together illustrate a flowchart depicting a system for rating carriers having checks and balances in accordance with an exemplary embodiment. [0026] FIGS. 19A and 19B together illustrate a flowchart depicting logic behind selection of a temporal range in accordance with an exemplary embodiment. [0027] FIG. 20 illustrates a screen shot for a carrier profile to access through one or more interfaces the features and functionality of FIG. 1 in accordance with an exemplary embodiment. [0028] FIG. 21 illustrates a screen shot depicting a load profile with quotes attached to a load with ratings. [0029] FIG. 22 illustrates a screen shot depicting a menu for interacting with a carrier rate on a load menu. [0030] FIG. 23 illustrates a screen shot depicting a customer profile. [0031] FIG. 24 illustrates a screen shot depicting a brand new load. [0032] FIG. 25 illustrates a screen shot depicting the selection of equipment for the new load depicted in FIG. 24 . [0033] FIG. 26 illustrates a screen shot depicting a new load and adding a line item to a customer's invoice. [0034] FIG. 27 illustrates a screen shot depicting realization of the line item added to the customer's invoice of FIG. 26 . [0035] FIG. 28 illustrates a screen shot depicting the ability to add a shipper and a receiver for a designated city and state. [0036] FIG. 29 illustrates a screen shot depicting a pop-up menu while selecting a temporal date range. [0037] FIG. 30 illustrates a screen shot depicting the pop-up menu of FIG. 30 while selecting a temporal time range. [0038] FIG. 31 illustrates a screen shot depicting the pop-up menu of FIGS. 30 and 31 while selecting a temporal “after” time range. [0039] FIG. 32 illustrates a screen shot depicting a realized selected temporal range implemented via actions depicted in FIGS. 29-31 . [0040] FIG. 33 illustrates a screen shot depicting automatically converted units of weight for a specific cargo over that entered in the screen shot of FIG. 32 . [0041] FIG. 34 illustrates a screen shot depicting a load status change “PUT ON HOLD” resulting from selection of a “POST TO LOAD BOARDS” field in FIG. 35 . [0042] FIG. 35 illustrates a screen shot depicting the adding of a carrier quote where permissions change the rate and “XYZ TRUCKING” is added. [0043] FIG. 36 illustrates a screen shot depicting the addition of a second carrier quote to provide for multiple quotes. [0044] FIG. 37 illustrates a screen shot depicting a carrier quote menu. [0045] FIG. 38 illustrates a screen shot depicting a pop-up menu for adding carrier quote equipment. [0046] FIG. 39 illustrates a screen shot depicting realized changes of carrier quote equipment type from FIG. 38 to FIG. 39 . [0047] FIG. 40 illustrates a screen shot depicting the addition of a note to a carrier. [0048] FIG. 41 illustrates a screen shot depicting realization of the added note input in FIG. 40 . [0049] FIG. 42 illustrates a screen shot depicting realizing equipment changes for the listed carrier with the added note and approval of “XYZ TRUCKING”. [0050] FIG. 43 illustrates a screen shot depicting realized changes for approved carrier “XYZ TRUCKING”. [0051] FIG. 44 illustrates a screen shot depicting creation of carrier rate paperwork. [0052] FIG. 45 illustrates a screen shot depicting a pop-up screen that provides a secondary check to a user indicating that this operation is desired by the user. [0053] FIG. 46 illustrates a screen shot depicting realization of carrier rate confirmation paperwork. [0054] FIG. 47 illustrates a screen shot depicting realization of customer rate confirmation paperwork. [0055] FIG. 48 illustrates a screen shot depicting selection of change of load status to “IN TRANSIT”. [0056] FIG. 49 illustrates a screen shot depicting realization of selection of the changed load status in FIG. 48 . [0057] FIG. 50 illustrates a screen shot depicting added notes to a load with carrier permissions to view. [0058] FIG. 51 illustrates a screen shot depicting that selection is being made for making it visible to a customer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0059] This disclosure is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8). [0060] FIG. 1 shows a platform or system 10 used to carry out temporal selection of a load to be delivered and a load to be scheduled for delivery by a carrier that is to be transported for a prospective transportation industry customer according to an exemplary embodiment. The system 10 includes a network, such as the Internet 12 , a server 14 , and terminals, or clients 16 , 18 , 20 , 22 , 24 and 26 . Server 14 includes one or more processor having processing circuitry 28 and data storage having memory 32 communicating with the processing circuitry. Memory 32 includes, or defines one or more databases 33 configurable to store data. Server 14 includes one or more network adapters 15 that enables communication with a network, such as the Internet 12 . Clients 16 and 18 comprise shipper terminals used by Shipper A and Shipper B, respectively. Clients 20 and 22 comprise broker terminals used by Broker A and Broker B, respectively. Clients 24 and 26 comprise carrier terminals used by Carrier A and Carrier B, respectively. Each client is further understood to include a wired or wireless communications device, memory, one or more processors having processing circuitry, an input/output device with a display driver for connecting the client to an input/output (I/O) device, such as a display, a keyboard, and a mouse. The display driver transforms digital data into visual images perceptible by a user at the client capable of generating screen images visible on the display. In several forms, client is a personal computer, a laptop, a tablet, or a smart phone. [0061] As shown in FIG. 1 , it is understood that one or more input modules can be generated by server 14 . Such modules are each configured to cause a graphical user interface to be rendered on a user's client machine, or computer to enable a user to input data relating to selection, scheduling, and delivery of a load (freight). Such interface renders features provided on the screen shots provided herein. Similarly, output modules are configured to display results of the data that is input by a user. [0062] FIG. 2 illustrates a flowchart for implementing user authentication and permissions to access through one or more interfaces the features and functionality of FIG. 1 in accordance with an exemplary embodiment. With reference to FIG. 2 , a flow of logic that is executed in various embodiments, when implementing user authentication and permissions is illustrated. The process can start at step 200 . After start 200 , the process proceeds to step 201 where a user public page is presented at one or more clients where a user can input their credentials. After step 201 , the process proceeds to step 202 where the input user credentials are sent via HyperText Transfer Protocol Secure (HTTPS) to server 14 (of FIG. 1 ). After performing step 202 , the process proceeds to step 203 where a user is authenticated (with a userid and a password). If the user is authenticated, then the process proceeds to step 204 . If the user is not authenticated, the process proceeds to step 201 . In step 204 , the process compares user type and user group to determine which category a user is identified with including a customer interface at step 205 , a carrier interface at step 206 and a “Type N” interface at step 207 . Once a user has been identified and assigned to a user category, the process proceeds to step 208 . In step 208 , the process prepares permissions and views based on a user sub-type, such as “broker”, “customer”, and “account manager”. After performing step 208 , the process proceeds to step 209 . In step 209 , a completely functional interface is displayed to the authenticated (identified) and permissioned user. [0063] FIG. 3 illustrates a flowchart for displaying load data to users and clients and for selecting and transmitting temporal data requirements for shipping the load. With reference to FIG. 3 , a flow of logic that is executed in various embodiments, when implementing the display of load data to users and clients and for selecting and transmitting temporal data requirements (date range and time range) is illustrated. The process can start at step 300 . In step 300 , a complete interface (with complete interface functionality) is displayed to a user at a specific client. After performing step 300 , the process proceeds to either step 301 or step 302 . In step 301 , a user searches for a load, then proceeds to step 302 . In step 302 , a user selects a load default from a list. After performing step 302 , the process proceeds to step 303 where a client sends a request to server 14 (of FIG. 1 ). After performing step 303 , the process proceeds to step 304 where the server returns load information to the client. After performing step 304 , the process proceeds to step 305 where the client displays the load data. After performing step 305 , the process proceeds to step 306 where the user selects a waypoint temporal data input field (such as a range of dates and/or a range of times) for which a designated load is to be picked-up/delivered to a desired destination. After performing step 306 , the process proceeds to step 307 where the client displays a user interface with a temporal data selector (a date range and/or a time range). After performing step 308 , the process proceeds to step 308 where the user inputs required temporal data (date range and/or time range). After performing step 308 , the process proceeds to step 309 where the client transmits the selected temporal data to the server 14 (of FIG. 1 ). After performing step 309 , the process proceeds to step 310 where the server stores the selected temporal data to an associated waypoint (a coordinate or location on the freight delivery path). [0064] As detailed in FIG. 3 , temporal date/time range storage is provided for logistics purposes. For each “waypoint” in a freight delivery (begin, midpoint, end, etc.) on a load to be transported, there exist pick-up and drop-off dates and/or times. There exist five different options to fill the temporal field with data including: “Between”; “Before”; “After”; “At”; and “N/A” (not available). These dates and times are then parsed in different ways in order to distribute them to industry standard load boards, such as GetLoaded, Dat360, and Internet Truckstop. Such distribution is an optional feature. [0065] As used herein, the terms “carrier rate”, “carrier bid”, and “carrier quote” are used interchangeably until a carrier is fully signed on for a load, after which the designation becomes “carrier-on-board”. [0066] FIGS. 4A and 4B together illustrate a flowchart for a customer selecting carrier bids, approving carrier rates, accepting carrier bids, and storing multiple customer approved bids on a load. With reference to FIGS. 4A and 4B , a flow of logic that is executed in various embodiments, when implementing the display of load data to users and clients and for selecting and transmitting temporal data requirements (date range and time range) is illustrated. The process can start at step 400 . After step 400 , the process proceeds either to step 401 or step 402 . In step 401 , a customer searches for a load using a specific client. After performing step 401 , the process proceeds to step 402 where a user selects a load default from a list of loads. After performing step 402 , the process proceeds to step 403 where the client sends a request to the server 14 (of FIG. 1 ). After step 403 , the process proceeds to step 404 where the server returns load information to the client. After step 404 , the process proceeds to step 405 where the clients displays load data. After step 405 , a query is made at step 406 as to whether a specific account type and load status is enabled to view bids. If not, the process proceeds to step 407 where a load is displayed without any bids. If enabled, the process proceeds to step 408 where all current carrier bids and/or quotes are displayed at a client (including multiple bids displayed concurrently). After performing step 408 , the process proceeds to step 409 where a customer selects a carrier bid from a list of currently submitted bids. After performing step 409 , the process proceeds to step 410 where a multi-variate query is made about four responses that can be taken after carrier bid information is displayed at a client. At step 410 , a user is presented with four choices. A first choice is triggered by a user selecting an approved button (on a user interface of the client) that causes the process to proceed to step 411 . A second choice is triggered by a user selecting a decline button (on a user interface of the client) that causes the process to proceed to step 422 . A third choice is triggered by a user selecting an add note/comment via a text box and submitting it that causes the process to proceed to step 423 . A fourth choice is triggered by a user selecting a click on name button (listing a static profile for a carrier) which proceeds to step 424 . After performing step 424 , the user then clicks on a back button to return the process back to step 410 . In step 411 , the customer approves the provided carrier rate. In step 422 , a customer denies a carrier rate and the process proceeds to step 414 . After a customer denies a rate at step 422 , the system changes the status of the bid relative to the customer's interface. In step 423 , a customer sends the carrier a message and the process proceeds to step 414 . After step 411 , the process proceeds to step 412 where the client sends approval to the server. After step 412 , the process proceeds to step 413 where the server marks the bid as approved. After step 414 , the process proceeds to step 414 where a notification is dispatched to the carrier and/or account representative. After step 414 , the process either proceeds back to step 409 or forward to step 415 . In step 415 , the server stores multiple customer approved bids on a load. After step 415 , the process proceeds to step 416 where individual carriers are notified of bid approval and asked to confirm their availability to deliver a specific load. After performing step 416 , the process proceeds to step 417 where the carrier responds by confirming their availability (to the server). After step 417 , the process proceeds to step 418 where the server sets the first carrier to respond to the load. After step 418 , the process proceeds to step 419 where the server updates the load past the bidding status. After step 419 , the process proceeds to step 420 where the server sends out notification to all non-conforming carriers that the specific load is closed (and not open for bid acceptance). More particularly, the term “closed” is applied to loads to denote that the load is delivered. After performing step 420 , the process proceeds to step 421 where the server sends out notification to the customer that a carrier has been set (or assigned) to carry their particularly load. At this point, the process terminates. [0067] As detailed in FIG. 4 , a multiple quote and simultaneous approval process is disclosed. When a customer is logged in and look at quotes that have been submitted by various carriers, they are enabled with the ability to approve multiple carriers at the same time. Once this happens, an automated notification goes out to all carriers approved, requesting confirmation of their availability. The first carrier that logs into the website and provides an availability verification to complete the load in question is then changed to become the provider. The remaining carriers are then automatically notified that they were too slow to become the provider, and the load is no longer available. [0068] FIG. 5 illustrates a screen shot of a web page for a simple request for a broker for posting loads and identifying shippers and receivers of a type that would be displayed on the screen of one of the computers connected for communication with the processing circuitry of the server for the system of FIG. 1 . More particularly, a cursor 501 is positioned over “Set Date & Time” field 502 which provides a selectable navigation link that opens up a temporal range pop-up window 601 depicted in FIG. 6 , below. [0069] FIG. 6 illustrates a screen shot of a web page for a date/time/selection menu that pops up when a user selects a “Set Date & Time” field 502 in one of the shipper and received fields of FIG. 5 . More particularly, pop-up menu 601 includes a temporal date range selection menu item 602 and a corresponding temporal time range selection menu 603 via which a user can select a temporal range (time and/or date) using a single click/drag of a mouse and cursor over the calendar displayed in selection menu 602 . A temporal date range is shown as selection field 606 . A selectable date identifier “At” 607 is selected in menu 601 corresponding with a single selected date shown in a date field 605 shown directly below. Another date indicated by menu item 604 representing Jan. 22, 2104 shows the current date via a round circle, whereas the “At” selected date will show up on the calendar via a rectangular surround feature corresponding with the date shown in date field 605 . Other date identifiers of menu 601 for selecting a date, or date range that are selectable include, “Between”, “Before”, “After”, and “Don't Set”. [0070] FIG. 7 illustrates a screen shot of a web page showing a user “mousing-over” and selecting date range field 606 (with a cursor) of temporal date range selection menu 602 separate from selecting a time range 609 via a “between” time field selection 608 of a temporal date range selection menu 602 . Furthermore, a temporal time range selection menu 603 is also provided for selecting and inputting dates for respective date ranges. [0071] FIG. 8 illustrates a screen shot of a web page showing a selected temporal range achieved in FIG. 7 . More particularly, a cursor 801 is positioned over a selectable navigation date range link 802 that opens up the temporal range pop-up window 601 depicted in FIG. 7 , above. [0072] FIG. 9 illustrates a screen shot of a web page showing selection of a receiver “Set Date & Time” field 902 by “mousing-over” a cursor 902 and selecting field 902 . More particularly, cursor p 01 is positioned over “Set Date & Time” 902 which provides a selectable navigation link that opens up a temporal range pop-up window 601 depicted in FIG. 10 , below. [0073] FIG. 10 illustrates a screen shot of a web page showing a selected temporal range for the pop-up menu of FIG. 6 that pops up when a user selects a “Set Date & Time” field 902 in the receiver field of FIG. 9 . More particularly, pop-up menu 601 includes a temporal date range selection menu item 602 and a corresponding temporal time range selection menu 603 via which a user can select a temporal range (time and/or date) using a single click/drag of a mouse and cursor over the calendar displayed in selection menu 602 . A temporal date range is shown by selection field 1006 . A date identifier “Between” 1008 is selected in menu 601 corresponding with a range of dates shown in a date field 1005 shown directly below. Another date indicated representing Jan. 22, 2104 shows the current date via a round circle. Other date identifiers of menu 601 for selecting a date, or date range that are selectable include, “At”, “Before”, “After”, and “Don't Set”. [0074] FIG. 11 illustrates a screen shot of a web page for realizing the temporal range selected in FIG. 10 . More particularly, a temporal date and time range 1102 and 1104 is provided for the shipper and the receiver, respectively. [0075] FIG. 12 illustrates a screen shot of a user login page having a login menu 1201 for receiving user login information including email adrees, and password information that enables permissioned login to features of the website portal described variously in FIGS. 1-52 . [0076] FIG. 13 illustrates a screen shot of a customer dashboard illustrating a customer's specific freight requests, or loads that a particular customer has pending. Loads are shown in various stages in any scenario. One exemplary shown freight request for shipping a freight load from Seattle, Wash. to Key West, Fla. is shown in field 1302 when a “My Freight” menu item 1304 is selected with a mouse (or input device) via cursor 1301 . A draft load request 1306 is shown for a load that the customer is still working on, but is not yet fully filled in and submitted. In contrast, field 1302 shows a customer name 1312 , an in-house tracking number 1318 for identifying a load, an originating location identifier 1314 with a preferred date of pickup identifier 1316 , and a destination location identifier 1320 with a preferred date of drop-off identifier 1322 . Furthermore, field 1302 includes a truck icon 1308 that traverses along a line 1310 from start location identifier 1314 at one end to finish location identifier 1320 at an opposite end. Position of truck icon 1308 is provide along line 1310 at a location corresponding with the distance presently travelled by the carrier with the cargo, as determined by GPS monitoring of the actual carrier (and cargo). In this way, a user of the system can monitor status (relative position) of the cargo and carrier relative to the total distance being traveled between the start location and the finish location during the delivery. [0077] FIG. 14 illustrates a screen shot showing customer load details in a detail menu 1402 including status of a load submitted and pending, as well as status of carrier approval. A status indicator field 1404 shows the status of a shipping request under review. [0078] FIG. 15 illustrates a screen shot showing a customer new load data entry input menu 1506 obtained by selecting a “Create New Load” identifier 1504 with a mouse cursor 1502 . Menu 1506 includes an explanation, or “How it works” explanation field 1508 , a “What are you shipping and where is it going?” field 1510 , a “Weight & Dimensions” field 1512 , and a “Shipping & Receiving Dates” field 1514 . [0079] FIG. 16 illustrates load details including a newly created load realized by accessing “Create New Load” field 1504 with a temporal range pop-up menu 1603 . Menu 1603 is generated by selecting “Preferred Earliest Pickup Date” field 1602 within field 1514 using a mouse cursor 1601 . [0080] FIG. 17 illustrates a flowchart for depicting account manager load interaction flow and privileges in accordance with an exemplary embodiment. With reference to FIG. 17 , a flow of logic that is executed in various embodiments, when implementing the creation and submission of load data is illustrated. The process can start at step 1700 . After step 1700 , the process proceeds to step 1701 where a load is created by a user. After performing step 1701 , the process proceeds to step 1702 where a query is made as to whether the created load has required data (for submission to the load boards). If so, the process proceeds to step 1704 . If not, the process proceeds to step 1703 . After step 1703 , the process terminates. In step 1703 , the load does not have required data and cannot be posted to the board(s). In step 1705 , the load board hooks are fired. After step 1706 , carriers add bids to the load on the load board. After performing step 1706 , the process proceeds to step 1707 where a broker approves a carrier (from those that have added a bid to the load). After performing step 1707 , the process proceeds to step 1708 where the load status changes to “waiting for pickup”. After performing step 1708 , the process proceeds to step 1709 where “waiting for pickup” hooks are fired that trigger a series of system events that are mandatory for that status of the load and operation of the system. After performing step 1709 , the process proceeds to step 1710 where a broker changes load status to “on road”. After performing step 1710 , the process proceeds to step 1711 where the load status on the system actually changes to “on road”. After performing step 1711 , the process proceeds to step 1712 where “on road” hooks are fired. After performing step 1712 , the process proceeds to step 1713 where the load status changed to “load delivered”. After performing step 1713 , the process proceeds to step 1714 where “load delivered” hooks are fired. After performing step 1714 , the load is marked “BOL received”. After performing step 1715 , the process proceeds to step 1716 where “BOL received” hooks are fired. After performing step 1716 , the process proceeds to step 1717 where broker privileges are changed to “view only” status. After step 1717 , the process is terminated. [0081] As detailed in FIG. 17 , the disclosed system provides for account management and accountability for brokers. First, account representatives (or brokers) cannot modify a load after it has been delivered. Secondly, all management of load after delivery is shifted to other departments. For example, after the shift (or lock-out), an exemplary account representative will only be enabled with the ability to view load and account information. Thirdly, only the accounting department can close a load after it has been delivered. Finally, only an administrator can modify the load outside of the normal flow process. A normal flow process for a brokered process proceeds sequentially, as follows: created ->submitted to boards->carriers add bids->broker approves carrier->load on road->load delivered->BOL (Bill of Lading) received->load closed (after billing). A normal flow process for a dispatched customer's flow process proceeds sequentially, as follows: draft->submitted to rep->submitted to boards->carriers add bids->customer approves bids->carrier signifies availability->load on road->load delivered->BOL received->load closed (after billing). [0082] FIGS. 18A and 18B together illustrate a flowchart depicting a system for rating carriers having checks and balances in accordance with an exemplary embodiment. With reference to FIGS. 4A and 4B , a flow of logic that is executed in various embodiments, when implementing a system of checks and balances in the process of rating carriers is illustrated. The process can start at step 1800 . In step 1800 , carrier data is modified from user input or external data. After performing step 1800 , the process proceeds to step 1802 . In step 1801 , the process can start when a user selects a black flag under a carrier profile. After performing step 1801 , the process proceeds to step 1802 . In step 1802 , a carrier status update starts. After performing step 1802 , the process proceeds to step 1803 where a query is implemented to determine whether a carrier has common or contract authority. If the carrier does have authority, then the process proceeds to step 1804 . If not, the process proceeds to step 1805 . In step 1804 , a query is implemented to determine if the carrier has cargo and auto insurance. If the carrier does have the insurance, the process proceeds to step 1807 . If not, the process proceeds to step 1805 . In step 1807 , a query is implemented to determine if the carrier is flagged “black”. If the carrier has been flagged “black”, the process proceeds to step 1805 . If not, the process proceeds to step 1808 . In step 1805 , the carrier is flagged “red”. In step 1808 , a query is implemented to determine if a carrier's insurance has been internally flagged as a high risk. If so, the process proceeds to step 1809 . If not, the process proceeds to step 1811 . After performing step 1805 , the process proceeds to step 1806 where carrier bids can be added, but not approved for any load. After performing step 1808 , the process proceeds to step 1809 where a carrier is flagged “yellow”. After performing step 1809 , the process proceeds to step 1810 where a carriers updated data and status are saved to a database. In step 1811 , a query is implemented to determine if a carrier contract or common authority is pending. If so, the process proceeds to step 1809 . If not, the process proceeds to step 1812 . In step 1812 , a query is implemented to determine if carrier cargo or auto insurance will expire within “X” days (X being a determined or set number of days, such as 30 days). If so, the process proceeds to step 1809 . If not, the process proceeds to step 1813 . In step 1813 , a query is implemented to determine if a carrier has proper attached paperwork to their profile. If so, the process proceeds to step 1814 . If not, the process proceeds to step 1809 . In step 1814 , a carrier is flagged “green”. After performing step 1814 , the process proceeds to step 1816 and to step 1810 . In step 1816 , the carrier bids can be approved and they can be assigned to the load. After performing step 1816 , the process terminates. In step 1815 , a broker determines if carrier status is relevant on a case-by-case basis. After performing step 1815 , the process proceeds to step 1806 and step 1816 . [0083] As detailed in FIG. 18 , the disclosed system provides for carrier compliance including an inter-office black list. Carriers are color coded for usability: namely, green (safe/insured), yellow (elevated risk/close to losing insurance), and red (risky/lost insurance). Notifications are provided if a particular carrier loses their insurance on a load (this data is pulled from both third-party systems and applicant's own internal management system). Such notifications are shown by item 2002 (of FIG. 20 ) and items 2110 and 2112 (of FIG. 21 ). Current logic for color coding is as follows: red is the worse case indicating no insurance; yellow is between red and green and indicates that insurance is soon at risk of loss; and green indicates insurance is in place and the carrier does not present a know risk. In addition, or optionally, black can be used to indicate that a carrier has been internally black-flagged, and should not be considered for any deliveries. If insurance is flagged due to an imminent lapse, a yellow designation is applied. If the carrier has neither common or contract authority, then a yellow designation is used. If no cargo or auto insurance is in place, a red designation is used. If cargo or auto insurance is going to expire in less than 30 days, then a yellow designation is used. All other cases will be provided with a green designation. Other suitable criteria for setting a risk-based color designation on a carrier include using information as to whether they have a W-9/EIN on file with applicant, as well as whether there is an existing contract in place with the carrier. [0084] FIGS. 19A and 19B together illustrate a flowchart depicting logic behind selection of a temporal range in accordance with an exemplary embodiment. The process can start at step 1900 . In step 1900 , a user opens a temporal modal. After step 1900 , the process proceeds to step 1901 where a user provides input from a mouse (or input device) at a client. From step 1901 , a user proceeds to one of steps 1902 , 1906 , 1910 , 1914 , 1918 , 1921 , 1923 , 1925 , 1929 , 1933 , and 1936 . In step 1902 , the user selects “BETWEEN”. After step 1902 , the process proceeds to step 1903 where the selected type is set. After step 1903 , a query is made to determine if the dates are set. If the dates are set, the process proceeds to step 1905 where days between the set (or selected) dates are highlighted (inclusive). After step 1905 , the process proceeds to step 1901 . If the dates are not set, the process proceeds to step 1901 . In step 1906 , the user selects “BEFORE”. After step 1906 , the process proceeds to step 1907 where the selected type is set. After step 1907 , a query is made at step 1908 to determine if the dates are set. If the dates are set, the process proceeds to step 1909 where days before the set (or selected) end date are highlighted (inclusive). After step 1909 , the process proceeds to step 1901 . If the dates are not set, the process proceeds to step 1901 . In step 1910 , the user selects “AFTER”. After step 1910 , the process proceeds to step 1911 where the selected type is set. After step 1911 , a query is made at step 1912 to determine if the dates are set. If the dates are set, the process proceeds to step 1913 where days after the set (or selected) start date are highlighted (inclusive). After step 1913 , the process proceeds to step 1901 . If the dates are not set, the process proceeds to step 1901 . [0085] In step 1914 , the user selects “AT”. After step 1914 , the process proceeds to step 1915 where the selected type is set. After step 1915 , a query is made at step 19126 to determine if the dates are set. If the dates are set, the process proceeds to step 1917 where only the start date is highlighted (inclusive). After step 1917 , the process proceeds to step 1901 . If the dates are not set, the process proceeds to step 1901 . [0086] In step 1918 , the user selects “N/A” (not available). After step 1918 , the process proceeds to step 1919 where the selected type is set. After step 1919 , the process proceeds to step 1920 where all highlights are removed. After step 1920 , the process proceeds to step 1901 . [0087] In step 1921 , the user selects “USE TIME”. After step 1921 , the process proceeds to step 1922 where the display of time input is toggled. After step 1922 , the process proceeds to step 1901 . [0088] In step 1923 , the user selects a time input. After step 1923 , the process proceeds to step 1924 where the user inputs time. After step 1924 , the process proceeds to step 1901 . [0089] In step 1925 , the user selects or clicks on a date. After step 1925 , the process proceeds to step 1926 where type is set to “AT”. After step 1926 , the process proceeds to step 1927 where start is set to the date selected. After step 1927 , the process proceeds to step 1928 where only the start date is highlighted. After step 1928 , the process proceeds to step 1901 . [0090] In step 1929 , the user clicks and drags between two dates. After step 1929 , the process proceeds to step 1930 where the type is set to “BETWEEN”. After step 1930 , the process proceeds to step 1931 where a user sets start and end to first and last dates selected. After step 1931 , the process proceeds to step 1932 where days between selected dates are highlighted. After step 1932 , the process proceeds to step 1901 . [0091] In step 1933 , the user selects “OK”. After step 1933 , the process proceeds to step 1934 where a temporal timeframe string is prepared. After step 1934 , the process proceeds to step 1935 where the timeframe string is passed to a parent object. After step 1935 , the process proceeds to step 1937 where the modal is closed. [0092] In step 1936 , the user selects “CANCEL”. After step 1936 , the process proceeds to step 1937 where the modal is closed. [0093] FIG. 20 illustrates a screen shot for a carrier profile for “FDC Enterprises LLC” to access through one or more interfaces the features and functionality of FIG. 1 in accordance with an exemplary embodiment. More particularly, the carrier profile of FIG. 20 shows [0094] FIG. 21 illustrates an account manager/broker screen shot depicting a load profile with quotes attached to a load with carrier ratings. More particularly, [0095] FIG. 22 illustrates an account manager/broker screen shot depicting a menu for interacting with a carrier rate on a load menu. Multiple quotes from unique sources (indicated by carriers 2106 and 2108 ) are shown, as further previously depicted by reference numeral 408 of FIG. 4B . More particularly, a note text field 2202 enables a user to input comments relating to that carrier bid and a selectable “Approve” button 2204 and “Decline” button 2206 enable a user to indicate approval or decline of a particular carrier bid. [0096] FIG. 23 illustrates a broker-side screen shot depicting a customer profile. More particularly, an “Account” type display field 2302 is shown above a “Loads” type display field 2308 . Field 2302 includes an “Account Type” field category 2304 with a presently displayed “Fully Brokered” field value, or visual indicia that is further represented by one of a series of vehicle representations by vehicle icon 2305 . Field 2304 correlates with item 406 in FIG. 4A . [0097] FIG. 24 illustrates a broker-side screen shot depicting a brand new load. A cursor is “moused-over” a preferred equipment “Unspecified” field 2402 which generates pop-up menu 2502 in FIG. 25 , below. [0098] FIG. 25 illustrates a screen shot depicting the selection of equipment for the new load depicted in FIG. 25 . More particularly, pop-up menu 2502 depicts a list of unique trailer types that can be selected by a user via menu 2502 . The list of unique trailer types is queried from a database of industry standard trailer types and transportation methods (including intermodal). A search box field 2504 is also provided for inputting and searching the database for a specific type of trailer or transportation method. [0099] FIG. 26 illustrates a screen shot depicting a new load and adding a new line item to a customer's invoice. More particularly, a pop-up menu 2602 is used to add a line item to a customer invoice based on industry-specific needs. The data input via menu 2602 is automatically provided as input into an accounting management program, such as Quick Books™. [0100] FIG. 27 illustrates a screen shot depicting realization of the line item added to the customer's invoice of FIG. 26 . More particularly, “Tarp/Tailgate” field 2702 has been added along with a value field entry 2704 of $150. [0101] FIG. 28 illustrates a screen shot depicting the ability to add a shipper and a receiver for a designated city and state. A “Route” data entry field 2802 is provided with a “Shipper” data entry field 2804 and a “Receiver” data entry field 2806 . Shipper waypoint location and load information is entered by a user into field 2804 . Receiver waypoint location and load information is entered by a user into field 2806 . [0102] FIG. 29 illustrates a screen shot depicting a pop-up menu 2902 while selecting a temporal date range. More particularly, a “Between” date range selection feature 2904 has been selected to enable a single tactile input gesture (such as click-and-drag operation) for selecting a range of dates. [0103] FIG. 30 illustrates a screen shot depicting the pop-up menu 2902 of FIG. 29 while selecting a temporal time range. A selected date range is shown for a “Shipper” as subsequently depicted in FIG. 32 . Encircled “5” indicates the present date. [0104] FIG. 31 illustrates a screen shot depicting the pop-up menu 2902 of FIGS. 29 and 30 while selecting a temporal “after” time range 3104 shown for a “Reciever” as subsequently depicted in FIG. 32 . More particularly, all dates after (and including) Feb. 19, 2014 are selected. [0105] FIG. 32 illustrates a screen shot depicting a realized selected temporal range implemented via actions depicted in FIGS. 29-31 . A selected date range 3202 and 3204 is shown for both the “Shipper” and the “Receiver”, respectively. Additionally, a “Weight” data entry field 3206 has received an input of “3T” (lb.). [0106] FIG. 33 illustrates a screen shot depicting automatically converted units of weight for a specific cargo over that entered in the screen shot of FIG. 32 . “Weight” data entry field 3206 has been automatically converted in units (from tons) into pounds (lb.). Additionally, automatic conversions of units, such as English and metric unit measures are implemented via such system and feature. Finally, a cursor 3201 is “moused-over” “POST TO LOAD BOARD” button which triggers posting of the input information to the load board. [0107] FIG. 34 illustrates a screen shot depicting a load status change “PUT ON HOLD” designated by item 3402 resulting from selection of a “POST TO LOAD BOARDS” field 3203 (in FIG. 33 ). Further details of the load status change are provided in FIG. 17 , above. [0108] FIG. 35 illustrates a screen shot depicting the adding of a carrier quote where permissions change the rate and “XYZ TRUCKING” is added. A notifications message window 3502 is shown after selecting “Notifications” selection item 3504 . [0109] FIG. 36 illustrates a screen shot depicting the addition of a second carrier quote indicated by reference item 3602 to provide for multiple quotes. Item 3602 represents a rate of $3,500 for “XYZ Transport” which comprises an “Open Quote”. [0110] FIG. 37 illustrates a screen shot depicting a carrier quote menu. More particularly, a cursor 3701 is “moused-over” a “No Equipment Specified” menu selection item 3702 which causes pop-up menu 3802 to be enabled in FIG. 38 . [0111] FIG. 38 illustrates a screen shot depicting a pop-up menu for adding carrier quote equipment. More particularly, pop-up menu 3802 depicts a list of unique trailer types that can be selected by a user via menu 3802 . The list of unique trailer types is queried from a database of industry standard trailer types and transportation methods (including intermodal). A search box field is also provided for inputting and searching the database for a specific type of trailer or transportation method. [0112] FIG. 39 illustrates a screen shot depicting realized changes of carrier quote equipment type from actions taken by a user depicted previously in FIG. 37 and FIG. 38 . [0113] FIG. 40 illustrates a screen shot depicting the addition of a note to a carrier. More particularly, “XYZ Trucking” text input field 4002 includes a note input field 4004 in which indicia, or text 4006 has been input by a user. [0114] FIG. 41 illustrates a screen shot depicting realization of the added note input in FIG. 40 . [0115] FIG. 42 illustrates a screen shot depicting realizing equipment changes for the listed carrier with the added note and approval of “XYZ TRUCKING”. A cursor 4201 is “moused-over” an “Approved” selection button, when clicked, causes the identified carrier to be approved on the load. A “Decline” selection button 4204 is also provided for declining that carrier. [0116] FIG. 43 illustrates a screen shot depicting realized changes for approved carrier “XYZ TRUCKING” resulting from selection of “Approved” selection button 4204 (in FIG. 42 ). In addition, a “Carrier” field 4302 now shows “XYZ Trucking”. An “Equipment” field 4304 shows “Cargo Van”. A carrier pay field 4306 shows “$3,900”. [0117] FIG. 44 illustrates a screen shot depicting creation of carrier rate paperwork. By selecting a lock icon 4308 above carrier pay field 4306 using cursory 4401 , it creates paperwork as shown below with reference to FIGS. 45 and 46 . [0118] FIG. 45 illustrates a screen shot depicting a pop-up screen 4502 that provides a secondary check to a user indicating that this operation is desired by the user. A user is presented with an “OK” selection button 4504 and a “Cancel” selection button 4506 for respectively launching or cancelling the “lock” to respective system data and limits the ability for values to be changed, such as permission-locking user access to only administrative or broker level personnel (other users will be prevented from unlocking the data and making changes). [0119] FIG. 46 illustrates a screen shot depicting realization of carrier rate confirmation paperwork which is triggered as a result of selecting “OK” button 4504 in FIG. 45 . As a result, “Paperwork” menu portion 4602 is shown having an added “Carrier Rate Confirmation” item 4604 . A carrier pay rate item 4606 is also provided as “$3,900”. [0120] FIG. 47 illustrates a screen shot depicting realization of customer rate confirmation paperwork. A cursor is shown selecting item 4606 which, in a locked state, generates a “disabled feature” icon 4702 . [0121] FIG. 48 illustrates a screen shot depicting selection of change of load status to “IN TRANSIT”. A cursor 4801 is shown selecting “MOVE TO IN TRANSIT” button 4802 which causes a screen display change represented below in FIG. 49 . [0122] FIG. 49 illustrates a screen shot depicting realization of selection of the changed load status in FIG. 48 . A “MOVE TO DELIVERED” button 4902 is then provided for selection by a user. [0123] FIG. 50 illustrates a screen shot depicting added notes to a load with carrier permissions to view. A cursory 5001 is provided (hovers) over a carrier note permissions icon 5002 . A tool tips, or pop-up box 5004 is generated to display the current carrier note permissions status. [0124] FIG. 51 illustrates a screen shot depicting that selection is being to enable viewing by the carrier of note text. [0125] In compliance with the statute, the subject matter disclosed herein has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the claims are not limited to the specific features shown and described, since the means herein disclosed comprise example embodiments. The claims are thus to be afforded full scope as literally worded, and to be appropriately interpreted in accordance with the doctrine of equivalents.

An apparatus is provided for improved processing of instructions to provide temporal selection to a client when scheduling a load to be transported for a prospective transportation industry customer. The apparatus includes a processor and a non-transitory machine readable memory. The processor is designed to process instructions to provide date and time selection to a client from a server to enable temporal scheduling of a load to be transported for a prospective transportation industry customer. The non-transitory machine readable memory at a host server has stored therein computer instructions programmed to cause the processor to store and access user information and instructions, and to present, enable, receive, store and associate date ranges, time ranges and waypoints for a load and cargo delivery destination. A method is also provided.

FIELD OF THE INVENTION [0001] The present invention relates to two wheeler stands. In particular, this invention relates to a device for providing improved safety in using a side stand for parking the two wheeled vehicle. BACKGROUND OF THE INVENTION [0002] Support stands are typically used to position a two wheeled vehicle in stationary position when not being driven by a rider. These stands have to be pushed open or extended from a closed inactive position to an open active position adapted to support the weight of the vehicle in a parked state. There are two types of stands commonly used to park a two wheeler. One of these stands is a side stand and the other is a centre stand. Both are provided between the wheel centers. To park a two wheeler using a stand, the support unit of the stand has to be swiveled to an open position and the vehicle pulled backwards or tilted to one side to achieve a parked stationary position. [0003] The centre stand of a two wheeler keeps the vehicles while parked, in plane normal to the ground level as compared to a slightly tilted position achieved while using a side stand. Both these stands are provided with stoppers to limit the movement of the stand with reference to the vehicle frame. A typical side stand for a two wheeler consists of bracket fastened to the frame of the vehicle, between the front wheel and rear wheels. The bracket is provided with a pivoted joint consisting of a swiveling support leg assembly. A spring is used to keep the leg assembly in a substantially horizontal position raised and away from the ground level, to prevent the stand from accidentally opening whilst the vehicle is in motion. Starting and riding a two wheeler with the side stand in a deployed state can lead to accidents and injuries to the rider and also to the bystanders. [0004] Various attempts have been made to alert the rider about the deployed state of the side stand support either by preventing engine start or alarms. [0005] U.S. Pat. No. 4,016,538 discloses a “Safety device for a motorcycle”. This device actuates the horn of a motorcycle if the side stand is down, the ignition is on, and the motorcycle is in the driving position using a mercury contact switch which is activated by the tilted position of the motor cycle when parked using a side stand and another switch mechanically connected to the stand. The horn is activated when the driver turns the ignition and brings the motor cycle to a substantially vertical position without putting up the side stand. The use of contact type switches and mercury filled position switch, acting in unison, to activate a sound alarm, is subject to wear and tear due to physical contact, electrical arcing, leakage of mercury and abrasion due to inclusion of dust particles. [0006] U.S. Pat. No. 6,733,025 discloses a “Motorcycle stand control mechanism”. This is a motorcycle stand control device having a rotor adapted to rotate when the wheels of the motorcycle is rotating. The rotor is provided with a set of magnets alternatively arranged around the periphery of the rotor and a circuit board having sensor adapted to act with the magnets and to output a corresponding control signal to turn the motorcycle stand of the motorcycle subject to the status of the rotary driven member. This device consists of many mechanical components like rotating wire positioned in a flexible cable to transmit the drive, direct current motor and gear drive to retract the side stand leg support. All these components are subject to high degree of mechanical wear and tear and the components that are exposed to the road surface and are likely to be damaged in inclement weather conditions and also not suitable for rough and rocky terrains. [0007] U.S. Pat. No. 6,918,607 discloses a “Side stand device”. This device consists of a rotary switch which attempts to prevent transmission of vibrations from a body frame to a rotary switch to reliably maintaining the function and performance of the rotary switch. The rotary switch is provided in coaxial relationship with the side stand through a pivot bolt and a securing bolt. A sheet is interposed between the rotary switch and the pivot bolt, and a tube and a sheet are interposed between the rotary switch and the securing bolt. The sheets and the tube are formed from rubber members. A cushion member is interposed between an engaging member of an inner rotor in the rotary switch and a locking hole of the side stand. The cushion member is formed from a rubber member. The cushioning members and the contacts of the rotary switch are subject to wear and tear and are likely to be damaged in regular use and have to be replaced during periodic maintenance. [0008] U.S. Pat. No. 7,631,885 discloses an “Intelligent interlock for a motorcycle stand”. This device consists of a side stand movable between an extended position in which the stand supports the motorcycle and a retracted position. The motorcycle includes a sensor to generate a signal to indicate the extended or retracted position of the side stand; a gear position sensor to generate signal about the neutral state or the non-neutral state of the transmission gears; a vehicle speed sensor to detect the speed of the motorcycle and a controller programmed for monitoring of the stand signal and for preventing operation of the engine when one of the gear position sensor and the vehicle speed sensor fails to communicate successfully with the controller, preventing operation of the engine being dependent upon the stand signal and an output of the other of the gear position sensor and the vehicle speed sensor. The stand position sensor is a Hall-effect sensor mounted externally and operates to sense the presence of the side stand in the retracted position by sensing a magnet or ferrous material of the side stand. The use of three different sensors and external mounting of the stand position sensor are likely to be damaged in inclement weather conditions, presence of magnets or ferrous particles and are also not suitable for rough and rocky terrains. [0009] Thus, there is a need for a device that warns the rider about the deployed condition of the side stand before he starts to ride the vehicle and which overcomes the problems hitherto encountered in a two wheeler having a side stand arrangement. OBJECTS OF THE PRESENT INVENTION [0010] An object of this invention is to provide a device that improves safety in using a side stand for parking the two wheeled vehicle. [0011] Still another object of this invention is to provide a safety device that positively indicates the deployment of the side stand of a two wheeler. [0012] Yet another object of this invention is to provide a safety device that is adapted to function even in adverse atmospheric conditions and in inclement weather. [0013] Yet another object of this invention is to provide a safety device that is free from wear and tear of the components and adapted to function accurately repeatedly. [0014] Yet another object of this invention is to provide a safety device that can function even at high ambient temperatures. [0015] Yet another object of this invention is to provide a safety device that is easy to install. [0016] Yet another object of this invention is to provide a safety device that does not require periodic servicing or maintenance to be carried out. BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS [0017] All aspects and advantages of the present invention will become apparent with the description of the preferred non limiting embodiment, when read together with the accompanying drawings, in which: [0018] FIG. 1 is the three dimensional view of the side stand of a two wheeler provided with the safety device in accordance with this invention, depicted in an operative position of the side stand; [0019] FIG. 2 is the exploded view of the side stand of a two wheeler provided with the safety device in accordance with this invention, as shown in FIG. 1 ; [0020] FIGS. 3 and 4 are the elevation and side elevation of the side stand of a two wheeler provided with the safety device in accordance with this invention, as shown in FIG. 1 , depicted in an operative position of the side stand; [0021] FIG. 5 is the sectional view of the side stand of a two wheeler provided with the safety device in accordance with this invention, as shown in FIG. 3 , depicted in an operative position of the side stand; [0022] FIGS. 6 and 7 are the elevation and side elevation of the side stand of a two wheeler provided with the safety device in accordance with this invention, as shown in FIG. 1 , depicted in an inoperative position of the side stand; [0023] FIG. 8 is the sectional view of the side stand of a two wheeler provided with the safety device in accordance with this invention, as shown in FIG. 6 , depicted in an inoperative position of the side stand; [0024] FIGS. 9 and 10 are the elevation and the end view of the base plate of the safety device in accordance with this invention as shown in FIG. 1 ; [0025] FIG. 11 is the three dimensional view of the housing of the safety device in accordance with this invention as shown in FIG. 1 ; [0026] FIGS. 12 and 13 are the elevation and sectional view of the plate holder of the safety device in accordance with this invention as shown in FIG. 1 ; [0027] FIGS. 14 and 15 are the plan and elevation of the fastener of the safety device in accordance with this invention as shown in FIG. 1 ; [0028] FIGS. 16 and 17 are elevation and end view of the printed circuit board of the safety device in accordance with this invention as shown in FIG. 1 ; and [0029] FIG. 18 is the functional diagram of the programmable mixed signal CMOS technology Hall-effect sensor used in the safety device in accordance with this invention as shown in FIG. 1 . SUMMARY OF THE INVENTION [0030] According to this invention there is provided a safety device for a side stand mounted on a two wheeled vehicle, said device comprising: [0031] a base plate adapted to be fastened to the frame of the two wheeler between the wheels centers, said base plate provided with specific peripheral cut out having two edges defining an included angle “X” between said edges; a holding member defining a first surface, an integral coaxial annular disc, a circular cavity and an arcuate cut out; said holding member pivot-ably mounted on the base plate; a move-able element rigidly mounted on said first surface of the holding member; a housing comprising a circular disc having an integral circular side wall defining a cavity provided with a central cylindrical projection normal to the circular disc; said central cylindrical projection defining at least three cylindrical locating regions; said circular disc provided with at least two spaced apart locating pins; said housing removably fastened to the base plate; an integrated circuit unit comprising a sensor unit, resistors-capacitors and pad connector points; said integrated circuit unit provided at least two mounting locations; in an assembled configuration the integrated circuit unit adapted to mount in said housing so as maintain specific orientation and locational accuracy with reference to the first locating region, mounting locations and said locating pins; a support element pivot ably mounted on said base plate; said support element adapted to swivel from an inoperative closed position to an operative open position within the included angle “X” of edges and; a fastener element provided with a central cylindrical cavity adapted to pivot-ably fasten said holding member with reference to the base plate; in an assembled configuration the circular cavity of the holding member adapted to receive the one end of the fastener and the central cylindrical cavity adapted to locate the third locating region of the housing so as to maintain specific orientation and locational accuracy of said move-able member with reference to the sensor unit in a first inoperative swiveled close position and an operative swiveled open position of the of the support element. [0032] Typically the included angle “X” is preferably more than 90 degrees but less than 125 degrees. [0033] Typically the move able element is a permanent magnet selected from a group of permanent magnets consisting of Alnico, Samarium-Cobalt, Neodymium-Iron-Boron magnets. [0034] Typically the integrated circuit unit is mounted on a rigid polymer base and covered with protective coating. [0035] Typically the sensor unit is a programmable digital Hall effect sensor. [0036] Typically the safety device of this invention is adapted to be retrofitted to a two wheeled vehicle. DESCRIPTION OF THE INVENTION [0037] The present invention relates to a safety device for the side stand of a two wheeler which overcomes the limitations hitherto encountered in existing devices employed for preventing accidents and injuries in using the side stand of the two wheeler. [0038] Referring FIG. 1 , the safety device for the side stand of a two wheeler in accordance with this invention is indicated generally by the reference numeral 100 . The safety device for the side stand of a two wheeler ( 100 ) comprises a base plate ( 1 ) adapted to be fastened to the frame (not specifically shown) of the two wheeler between the wheels centers. The base plate ( 1 ) is provided with a pivot able support element ( 6 ). A housing ( 4 ) is provided to secure the components of the safety device ( 100 ). [0039] FIG. 2 is the exploded view of the safety device for the side stand of a two wheeler ( 100 ) comprising base plate ( 1 ); a holding member ( 2 ); a move-able element ( 3 ); a housing ( 4 ); an integrated circuit unit ( 5 ); a support element ( 6 ); and a fastener element ( 7 ). The holding member ( 2 ) and the support element ( 6 ) are pivot ably secured to base plate ( 1 ) by the fastener element ( 7 ). The move-able element ( 3 ) is rigidly secured to the holding member ( 2 ). The integrated circuit unit ( 5 ) positioned within the housing ( 4 ). The housing ( 4 ) is removably fastened to the base plate ( 1 ) of the safety device for the side stand of a two wheeler ( 100 ). [0040] Referring to FIGS. 3 and 4 the safety device for the side stand of a two wheeler ( 100 ) is in an operative swiveled open position of the support element ( 6 ). In this operative condition (refer FIG. 5 ) the move-able element ( 3 ) positioned in close proximity of the integrated circuit unit ( 5 ). A sensor (not specifically shown in this view) embedded in the integrated circuit unit ( 5 ) is adapted to sense the relative position of the move-able element ( 3 ) and generate an output signal to indicate of the operative swiveled open position of the support element ( 6 ). [0041] Referring to FIGS. 6 and 7 the safety device for the side stand of a two wheeler ( 100 ) is in an inoperative swiveled close position of the support element ( 6 ). In this inoperative condition (refer FIG. 8 ) the move-able element ( 3 ) is positioned angularly displaced to be relatively away from the integrated circuit unit ( 5 ). The sensor (not specifically shown in this view) embedded in the integrated circuit unit ( 5 ) is adapted to sense the relative position of the move-able element ( 3 ) and generate an output signal to indicate of the inoperative swiveled closed position of the support element ( 6 ). [0042] Referring to FIGS. 9 and 10 the base plate ( 1 ) of the safety device for the side stand of a two wheeler ( 100 ) is provided with circular opening ( 15 ) adapted to receive the fastener element ( 7 ) (not specifically shown). The base plate ( 1 ) is also provided with specific peripheral cut out having two edges ( 17 ) and ( 19 ) defining an included angle “X” between said edges. [0043] In an assembled operative condition of the safety device for the side stand of a two wheeler ( 100 ) the fastener element ( 7 ), the holding member ( 2 ) and the support element ( 6 ) (not specifically shown in these figures) are adapted to be angularly displaced with reference to the centre of said circular opening ( 15 ). Said displacement limited within the included angle “X” defined by edges ( 17 ) and ( 19 ). [0044] Referring to FIG. 11 the housing ( 4 ) of the side stand of a two wheeler ( 100 ) comprises of a circular disc ( 25 ) provided with an integral circular side wall ( 27 ) so as to define a cavity provided with a central cylindrical projection ( 31 ) normal to the circular disc ( 25 ). The central cylindrical projection ( 31 ) defining three cylindrical locating regions ( 33 ) ( 35 ) and ( 37 ) having different diameters. In an assembled operative condition of the safety device for the side stand of a two wheeler ( 100 ) the cylindrical locating regions ( 33 ) ( 35 ) and ( 37 ) are adapted to locate and position the integrated circuit unit ( 5 ), the holding member ( 2 ) and the fastener element ( 7 ) respectively, so as to maintain concentricity and air gap of the assembled components in an inoperative swiveled closed position and in an operative swiveled open position of the support element ( 6 ). Two spaced apart locating pins ( 39 ) provided on the circular disc ( 25 ) are adapted to locate the integrated circuit unit ( 5 ). The circular side wall ( 27 ) is provided with an ingress opening ( 41 ) for cable harness connection to the integrated circuit unit ( 5 ). [0045] Referring to FIGS. 12 and 13 the holding member ( 2 ) of the safety device for the side stand of a two wheeler ( 100 ) is an arcuate member provided with a circular opening defining a first surface ( 45 ) provided with an integral coaxial annular disc ( 47 ) adapted to engage and coaxially locate the holding member ( 2 ) in the cylindrical locating region ( 35 ) of the cylindrical projection ( 31 ) provided on the housing ( 4 ) of the safety device for the side stand of a two wheeler ( 100 ). The holding member ( 2 ) further defining a circular cavity ( 49 ) adapted to coaxially locate the a fastener element ( 7 ) and an arcuate cut out ( 51 ) adapted to locate the support element ( 6 ). [0046] Referring to FIGS. 14 and 15 the fastener element ( 7 ) is provided with an hexagonal profile ( 55 ) at one end of a cylindrical surface ( 57 ) and adjoining threaded end ( 59 ). The fastener element ( 7 ) is also provided with a central cylindrical cavity ( 61 ) at the hexagonal end. In an assembled configuration of the safety device for the side stand of a two wheeler ( 100 ) the cylindrical cavity ( 61 ) is adapted to receive the cylindrical locating region ( 37 ) of the cylindrical projection ( 31 ) provided on the housing ( 4 ). [0047] Referring to FIGS. 16 and 17 the integrated circuit unit ( 5 ) is a substantially semicircular disc having a central cutout. the components of the integrated circuit unit ( 5 ) include a sensor unit ( 65 ) resistors and capacitors ( 69 ) and pad connector points ( 67 ) for conducting the signal generated by the sensor unit ( 65 ) to a controller unit (not included in this invention) adapted to read the signal received and generate audio or visual alerts and prevent engine start of the two wheeler engine. The integrated circuit unit ( 5 ) is also provided two mounting location holes ( 71 ) complementary to the spaced apart locating pins ( 39 ) provided on the circular disc ( 25 ) of the housing ( 4 ). These mounting location holes ( 71 ) accurately locate the integrated circuit unit ( 5 ) within the housing ( 4 ), maintaining the relative angular location of the sensor unit ( 65 ) with reference to the move-able element which is rigidly secured to the holding member ( 2 ). The printed circuit board is mounted on a rigid polymer base ( 73 ) and covered with protective coating ( 75 ) The cylindrical locating regions ( 33 ) ( 35 ) provided on the central cylindrical projection ( 31 ) of the housing ( 4 ) locate and maintain the positional accuracy and the air gap between the sensor unit ( 65 ) and the move-able element ( 3 ). [0048] The sensor unit ( 65 ) typically is a complementary metal oxide semiconductor (CMOS) Hall sensor having facility to switch the direction of current through the Hall elements thereby eliminating the offset errors typical of semiconductor Hall elements. Other features like preset-able functional characteristics like gain, offset, temperature coefficient of gain (to compensate different magnetic materials thermal dependencies) provides programmable algorithms for complex signal processing in real time. [0049] In this invention a change in the magnetic flux intensity causes a protected, magnetically biased pre-programmed sensor to go in a precise switch mode. The switching and hysteresis is controlled by the profile of a ferrous strip positioned accurately with controlled air gap between the face of the ferrous strip face and the sensing location of the sensor. A Complementary metal-oxide-semiconductor (CMOS) type Hall effect sensor was used. The Hall effect switch was mounted on a sturdy printed circuit board having a bias magnet, short circuit, reverse polarity protection and with a metal-oxide-semiconductor field-effect transistor (MOSFET) for output indication. The sensor used has wide operational parameters, with an operating voltage range of 2.7V to 24V, a magnetic latch range of ±0.4 mT to ±80 mT and a magnetic switch range of ±1.5 mT to ±66 mT and a programmable hysteresis range between 1 mT and 36 mT. The negative thermal coefficient can be adjusted in the range of 0 to −2000 ppm/° C. to match all currently available permanent magnet materials or to use with electromagnet (current sensing) actuation. This device has an operational temperature range spanning −40° C. to +150° C., making it highly suited for use in demanding automotive or industrial environments. [0050] The Hall effect sensor used for testing the invention was a “Melexis” programmable unit. Referring to FIG. 18 the functional diagram of the programmable Hall-effect sensor provided with mixed signal CMOS technology, includes a voltage regulator, Hall sensor with advanced offset cancellation system and an open-drain output driver, all provided in a single package. The sensor is provided with built-in reverse voltage protection therefore a serial resistor or diode on the supply line is not required and the sensor function effectively at low voltage operation down to 2.7V while being reverse voltage tolerant. In the event of a drop below the minimum supply voltage during operation, the under-voltage lock-out protection will automatically freeze the device, preventing the electrical perturbation to affect the magnetic measurement circuitry. The open drain output is fully protected against short-circuit with a built-in current limit. An additional automatic output shut-off is activated in case of a prolonged short-circuit condition. A self-check is then periodically performed to switch back to normal operation if the short-circuit condition is released. The on-chip thermal protection also switches off the output if the junction temperature increases above an abnormally high threshold. It will automatically recover once the temperature decreases below a safe value. [0051] The advantages of this invention includes: [0052] 1. There are no wear and tear of the components used in the device as the sensing the position of the side stand and generating appropriate signal is fully contact less. This ensures error free sensing in more than one million repetitions. [0053] 2. The components of the device are fully enclosed in a dust and weather proof housing ensuring maintenance free operation. [0054] 3. The extent of angular displacement and locational accuracy is controlled by the complementing projections and openings provided in the housing. [0055] 4. The air gap between the moveable and the fixed components within their entire range of angular displacement is constant. This ensures non varying signal generation repeatedly. [0056] 5. This device may be fitted on varying models and types of two wheelers as modification is required only in the base plate that is used for mechanical fitment. Within the same model or type of two wheeler the variations of vehicle body part and side stand does not adversely affect on the switching performance. This makes the fitment of the unit to the vehicle easy requiring low skill levels. [0057] 6. As the sensor unit is pre-programmable, over a wide range of design variables as required for different models and types of two wheelers, the inventory cost in manufacturing is reduced considerably and the device is highly suitable of for just-in-time inventory management practice at the vehicle assembly line. [0058] While considerable emphasis has been placed herein on the particular features of “a device for providing improved safety in using a side stand for parking the two wheeled vehicle” and the improvisation with regards to it, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiment without departing from the principles of the invention. These and other modifications in the nature of the invention or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is. to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

A device adapted for accurate and quick assembly on a two wheeled vehicle for enhanced safety in using a side stand for parking of the vehicle is disclosed.

This is a divisional of co-pending application Ser. No. 07/188,985, filed on Apr. 29, 1988, now U.S. Pat. No. 5,138,055, which is a continuation of application Ser. No. 06/864,622 filed May 16, 1986, now U.S. Pat. No. 4,742,118. The present invention relates to new and improved urethane-functional amino-s-triazine crosslinking agents, to curable compositions incorporating them and to methods of making and using the new and improved crosslinkers. More particularly, it relates to novel s-triazine compounds containing at least one N,N-bis(alkoxy- or hydroxyalkoxy-carbonylamino C 2 -C 10 alkyl)amino substituent. The novel urethane functional s-triazine crosslinking agents are useful for crosslinking active-hydrogen materials to form cured products characterized by excellent toughness, hardness and flexibility. They are especially useful for providing curable light-stable coatings for articles intended for outdoor use. BACKGROUND OF THE INVENTION Crosslinking agents comprising s-triazine compounds are known in the art. Koral et al., U.S. Pat. No. 3,661,819, for example, disclose a family of s-triazine curing agents comprising fully or partially alkylated melamine-formaldehyde compounds having the formula: ##STR1## or (ii) a benzoguanamine compound of the formula: ##STR2## wherein R is hydrogen or alkyl of from 1 to 12 carbon atoms. It is also known to use oligomers of such compounds, which are low molecular weight condensation products containing for example two, three or four triazine rings, joined by --CH 2 OCH 2 -- linkages, as well as mixtures of any of the foregoing. These are used to self-condense or used to cure active hydrogen-containing materials, especially polymers which contain carboxyl groups, alcoholic hydroxy groups, amide groups and groups convertible to such groups, such as methylol groups. Coatings containing melamine-formaldehyde crosslinkers have good hardness and high crosslink density. The coatings generally do not discolor upon exposure to light, especially ultraviolet from sunlight or other sources, moisture or oxygen. A serious shortcoming of these cross-linkers is that they tend to liberate formaldehyde on curing which is objectionable to both formulators and end-users. Moreover, coatings crosslinked with these materials have a tendency to brittleness, at least as compared with other coatings such as polyurethane coatings. Crosslinking agents based on beta-hydroxyalkyl carbamates are known from Valko, U.S. Pat. No. 4,435,559. Valko describes curable compositions comprising a bis(beta hydroxyalkyl carbamate) crosslinker, an active-hydrogen material and a cure catalyst. The Valko crosslinkers are prepared from diisocyanate intermediates. The coatings derived from aromatic blocked diisocyanates are not light stable in outdoor use. Although coatings prepared therefrom are more flexible than the aforementioned melamine-formaldehyde based coatings, they suffer from poor cross-link density, poor hardness and poor organic solvent resistance. Moreover, they require use and handling of hazardous and toxic isocyanate materials. Another patent dealing with beta-hydroxyalkyl carbamate crosslinkers is Jacobs, III, Parekh and Blank, U.S. Pat. No. 4,484,994, which discloses their use in cathodically electrodepositable coating compositions. Accordingly, to overcome certain drawbacks of the prior art crosslinkers, it is an object of the present invention to provide new and improved crosslinking agents for use with active hydrogen containing materials and polymers which impart the hardness, toughness, solvent resistance and light stability of melamine-formaldehyde crosslinkers but without the brittleness, and which possess the abrasion resistance and flexibility of polyurethane coatings. It is another object of the present invention to provide melamine-urethane crosslinkers for curable systems which are formaldehyde and isocyanate free. It is a further object of the present invention to provide curable coating compositions for use in powder coating, electrocoating and solvent-borne coating applications. SUMMARY OF THE INVENTION In accordance with these and other objects, the present invention provides new and improved urethane-functional s-triazine crosslinking agents comprising: (i) a compound of the formula ##STR3## wherein R 1 is ##STR4## wherein A 1 and A 2 are, independently, straight or branched chain divalent alkylene of from about 2 to about 10 carbon atoms and Q 1 and Q 2 are, independently straight or branched chain alkyl or alkoxyalkyl of from about 1 to about 20 carbon atoms or straight or branched chain beta-hydroxyalky of from about 2 to about 10 carbon atoms; R 2 and R 3 are, independently, the same as R 1 and, in addition, Cl, Br, I, OR 4 , --NHR 5 , --NR 5 R 6 , ##STR5## and R 4 , R 5 , R 6 are, independently, a monovalent- and R 7 is a divalent aliphatic, cycloaliphatic, aromatic or alkylaromatic radial, which can contain heteroatoms such as O, N, S or P, either in the chain or as side substituents and R 8 and R 9 are the same as R 4 , R 5 and R 6 and, in addition, hydrogen or, when R 7 , R 8 and R 9 are taken together, divalent heterocyclic incorporating the nitrogens to which they are attached; (ii) a self-condensed oligomer of (i); (iii) a urethane or urea compound comprising the reaction product of (i) or (ii) with a mono- or polyol or a mono- or polyamine; or (iv) a mixture of any of the foregoing. With respect to compound (i) A 1 and A 2 are preferably C 2 -C 6 alkyl and Q 1 and Q 2 are beta-hydroxyethyl, beta-hydroxy propyl, e.g., a mixture of beta-hydroxy-alpha-methylethyl and beta-hydroxy-beta-methylethyl, or a mixture of beta-hydroxypropyl and butyl or octyl. Also preferred are oligomers of (i) in which A 1 and A 2 are ethylene and Q 1 and Q 2 are beta-hydroxyethyl or beta-hydroxypropyl, as well as triazines in which R 2 and R 3 are the same as R 1 . Also contemplated by the present invention are thermosettable compositions comprising: (a) a cross-linking agent comprising: (i) a triazine compound selected from a compound of the formula: ##STR6## wherein R 1 is ##STR7## wherein A 1 and A 2 are, independently, straight or branched chain divalent alkylene of from about 2 to about 10 carbon atoms and Q 1 and Q 2 are, independently straight or branched chain alkyl or alkoxyalkyl of from about 1 to about 20 carbon atoms or straight or branched chain beta-hydroxyalky of from about 2 to about 10 carbon atoms; R 2 and R 3 are, independently, the same as R 1 and, in addition, Cl, Br, I, OR 4 , --NHR 5 , --NR 5 R 6 , ##STR8## and R 4 , R 5 , R 6 are, independently, a monovalent- and R 7 is a divalent aliphatic, cycloaliphatic, aromatic or alkylaromatic radical, which can contain heteroatoms such as O, N, S or P, either in the chain or as side substituents and R 8 and R 9 are the same as R 4 , R 5 and R 6 and, in addition, hydrogen or, when R 7 , R 8 and R 9 are taken together, divalent heterocyclic incorporating the nitrogens to which they are attached; (ii) a self-condensed oligomer of (i); (iii) a urethane or urea compound comprising the reaction product of (i) or (ii) with a mono- or polyol or a mono- or polyamine; or (iv) a mixture of any of the foregoing, and, optionally, (b) a polymer containing two or more active hydrogen functional groups; and (c) optionally, a cross-linking catalyst; the cross-linking agent (a) and the polymer (b) being stable relative to each other in the composition at ambient temperature and reactive with each other at elevated temperature. In preferred features of this aspect of the invention, the material (b) contains at least two reactive carboxyl, alcoholic hydroxy or amide groups, or a mixture of such groups, preferably a hydroxy-functional acrylic resin, a polyester polyol or a polyether polyol. Preferably the triazine will be as set forth specifically above, and the cure catalyst, if used, will be a metalorganic compound or quaternary salt, as set forth hereinafter. Alternatively, the urethane-functional s-triazine compounds of the above formulae can be used as (a) a self-crosslinkable material, alone, or (b) with an optional catalyst in providing protective and/or decorative coatings and binders. Also provided by the invention are articles of manufacture comprising substrates protectively coated with a baked and cured composition as defined above. Also in accordance with this invention there is provided a novel process for the preparation of a triazine compound of the formula ##STR9## wherein R a 1 is ##STR10## wherein A 1 and A 2 are, independently, straight or branched chain divalent alkylene of from about 2 to about 10 carbon atoms and Q a 1 and Q b 2 are, independently, straight or branched chain beta-hydroxyalkyl of from about 2 to about 10 carbon atoms; R 2 and R 3 are, independently, the same as R a 1 and, in addition, Cl, Br, I or OR a 4 , wherein R a 4 is monovalent aliphatic of from about 1 to about 6 carbon atoms, said process comprising reacting a compound of the formula ##STR11## with a compound of the formula ##STR12## wherein at least one of X, Y and Z are displaceable groups selected from Cl, Br, I or --OR a 4 and any remaining groups are non-displaceable groups of the formula wherein A 1 , A 2 , Q a 1 , and R a 4 are as defined above, optionally in the presence of a condensation catalyst, until formation of the desired compound is substantially complete and, if desired, reacting a product having no more than one of said displaceable groups X, Y and Z with a dialkylamine to form a dimer, self-condensing the product to an oligomer, or forming a urethane or urea compound comprising a product from any such compound having at least one of said displaceable groups by reaction with a mono- or polyol or a mono- or polyamine, and recovering said products. DETAILED DESCRIPTION OF THE INVENTION As starting materials to produce the urethane-functional s-triazine crosslinking agents of this invention, there can be used the triazine, such as cyanuric chloride, and/or obvious chemical equivalents thereof known in the art. Many of the starting materials are commercially available, and they can be made by well known procedures. In accordance with the present invention, the starting materials are reacted with a bis-hydroxyalkyl iminodiethylene dicarbamate made, for example, by reacting a cyclic alkylene carbonate with a polyalkylenepolyamine, such as diethylenetriamine. The preparation of the bis-hydroxyalkyl iminodiethylene biscarbamates is described in U.S. patent application Ser. No. 581,006, filed Feb. 17, 1984. The above-cited Valko patent describes making 2-hydroxyalkyl carbamates by reacting 1,2-diols with isocyanates. The mole ratio of beta-hydroxyalkyl carbamate to triazine compound is selected to provide the desired degree of substitution. As will be seen by the examples herein, the reactants are mixed in suitable media, such as water-acetone-alkanol mixtures, preferably in the presence of an acid acceptor, such as sodium hydroxide, if, for example, cyanuric chloride is used as the source of the triazine ring. Low temperatures, e.g., below about 20° C. promote the formation of mono-substituted products, higher temperatures, e.g., between about 25° and 70° C. favor the formation of di-substituted products; and still higher temperatures, e.g., above about 100° C. favor tri-substitution. Recovery of the product is conventional, e.g., by precipitation and washing free of any acidic byproduct or basic acid acceptor. The monomeric products of the process can be self-condensed to produce oligomeric compounds, suitable such compounds, e.g., monochlorotriazines can also be dimerized, e.g., by reacting with diamines, such as piperazine, and they can also be functionalized with amines, such as piperidine, as will be exemplified. Transesterification with alcohols, polyols, monoamines and polyamines also produce useful derivatives, as will be shown. The substituents defined by A 1 , A 2 , Q 1 and Q 2 , as well as R-R 7 in the Formulae above can vary widely in carbon content, and the groups can be straight chain, branched chain and alicyclic. Representative compounds will be exemplified hereinafter. ##STR13## The composition containing the crosslinking agents, polymers, and, optionally, catalyst, is heated to an elevated temperature at which the hydroxyalkyl carbamate groups of the cross-linker react with active functional groups of the polymer to cross-link the polymer and produce diol leaving groups of low toxicity, such as propylene glycol or ethylene glycol. A typical reaction sequence of, for example, a hydroxy functional group containing polymer of shown in equation (1) and that for an amine functional group containing polymer is shown in equation (2). ##STR14## With carboxyl functional group polymers, amide groups are formed in the reaction and the reaction products of the cross-linking reaction are CO 2 and the corresponding 1,2-diol. Generally, the leaving groups in the cross-linking reaction are, as illustrated above, diols of low toxicity, such as propylene glycol or ethylene glycol. Any attempt to prepare the above described hydroxyalkyl carbamate compounds by reaction of a diisocyanate with a di- or polyol would be difficult or impossible inasmuch as the formation of polyurethane polymers or gelation would occur. The amount of hydroxyalkyl carbamate selected in a typical formulation will of course depend on the cross-linking density desired. Typically, the proportion and compositions of resin and cross-linker are selected to provide from about 0.2 to about 5 moles of hydroxyalkyl carbamate groups per mole of active functional group on the polymer. If larger proportions of cross-linker carbamate groups to functional sites on the polymer are used, the cross-linker will also undergo some self-condensation, as shown in equation (3). ##STR15## The cross-linkable resins utilizable in the present invention may comprise any suitable polymer containing active hydrogen functional groups, i.e., suitable functional groups which will react, upon heating, preferably upon heating in the presence of a catalyst, with the urethane functional groups on the cross-linker of the invention. Such active groups comprise hydroxyl, amine, amide, thiol and carboxyl groups and, accordingly, resins containing such groups are utilizable in the practice of the invention. The functionality of the polymers employed can be as low as 2 but is preferably 3 or higher, and the molecular weight may range, for example, from about 300 to about 100,000. For example, acrylic polymers useful in the invention usually have a molecular weight range of from about 1,000 to about 50,000. A typical functional group content of, for example, hydroxyl resins utilizable in the invention is from about 0.5 to about 4 milliequivalents ("meq") hydroxyl per gram of resin solids. An illustrative, but by no means exhaustive, list of polymers which may be usefully employed in the invention includes acrylic, polyester, vinyl, epoxy, polyurethane, polyamide, cellulosic, alkyd and silicone resins. Acrylic resins useful in the invention can be derived from the acrylic acid or methacrylic acid esters of C 1 to C 18 aliphatic alcohols. Optionally, acrylonitrile, styrene or substituted styrene can be incorporated into the polymer. Additional comonomers suitable for such use are maleic or fumaric acid esters or half esters. Functional groups can be derived from the hydroxyalkyl esters of acrylic, methacrylic, maleic or fumaric acid. Carboxyl functionality can be derived from alpha and beta unsaturated carboxylic acids such as those mentioned below. Polyester and alkyd resins suitable for use with the urethane-functional triazine cross-linker can be derived from diols, polyols, mono-, di-, and polybasic acids. Examples of such suitable diols or polyols are ethylene glycol, propylene glycol, 1,3-butylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, trimethylpentane diol, cyclohexanedimethanol, trimethylolpropane, trimethylolethane and glycerine pentaerythritol. Typical carboxylic acids useful in preparing hydroxy and carboxyl functional polyester and alkyds are C 8 to C 18 aliphatic monocarboxylic acids, C 4 to C 10 aliphatic dicarboxylic acids, aromatic mono-, di, and tricarboxylic acids such as benzoic acid, o-, m-, p-phthalic acids, or tri-mellitic acid, dimeric fatty acids, and hydroxy carboxylic acids such as dimethylol propionic acid or caprolactone. Vinyl polymers particularly suitable for use in the invention are hydroxy and carboxyl functional group-containing polymers containing either vinyl chloride or vinyl acetate as one of the comonomers. Epoxy resins particularly suitable for use in the invention are hydroxy or amine functional resins. These are normally derived from bisphenol-A, bisphenol-F, or phenol formaldehyde resins and epichlorohydrin. The epoxy resins may also be formed from cycloaliphatic epoxies. Polyurethanes particularly suitable for use in the invention may be hydroxyl, carboxyl, or amine functional and may be derived either from polyester or polyether polyols and a polyisocyanate. Polyamides particularly suitable for use in the invention may be either amine or carboxyl functional and can be obtained by the conventional techniques of condensing polybasic acids with polyamines or by reacting polyamines with caprolactam. Cellulose based hydroxyl functional resins such as cellulose acetobutyrate, and hydroxyethyl cellulose can also be reacted with the hydroxyalkyl carbamate-containing amines of the invention. Hydroxy functional silicones can also be cross-linked with the hydroxyalkyl carbamate cross-linker and are therefore well-suited for use in the invention. All of the above mentioned active functional group-containing resins can be used in either organic solvent solution, as a powdered solid, or as dispersions in water or organic co-solvent aqueous solutions. Depending on resin structure, these uncross-linked polymers will be preferably used in one of the above mentioned forms. Blends of two or more of the above polymers can also be used. Further, the polymer and carbamate cross-linking agent blend may be pigmented, as is known in the art, to achieve a desired appearance of the coating. Depending on the application process, either a solid powder or a liquid is applied onto the substrate to be coated and after evaporation of any solvent present, the system is cured for a sufficient period of time, e.g., from several minutes to several hours, at temperatures sufficient to effect cure, e.g., from about 200 to about 400° F. (about 93 to 204° C.). A cross-linking catalyst may be used to promote cross-linking of the thermosetting composition of the invention. The catalyst may be an external catalyst or it may be incorporated as an internal catalyst during preparation of the functional group-containing resin, as is known in the art. For example, quaternary ammonium hydroxide groups may be incorporated into the resin. Any suitable crosslinking catalyst may be utilized (such as known metal-containing catalysts, e.g., lead, tin, zinc, and titanium compounds) as well as ternary or quaternary compounds as described below. Benzyltrimethyl ammonium hydroxide, dibutyltindilaurate, tetrabutyl diacetoxy stannoxane and similar compounds are good catalysts for achieving cross-linking at elevated temperatures in the range of from about 100 to about 175° C. (about 212 to about 347° F.) for a period of a few seconds to about 30 minutes. A catalyst may be present in a formulation in the amount of from about 0.1 to about 10% by weight of the polymer, preferably from about 1 to about 5% by weight of the polymer. The catalyst may comprise ternary or quaternary catalysts such as known compounds of the formula: ##STR16## where R p , R q , R r and R s may be equivalent or different and may be a C 1 to C 20 aliphatic, aromatic, benzylic, cyclic aliphatic and the like, where M may be nitrogen, phosphorus, or arsenic (to provide, respectively, quaternary ammonium, phosphonium or arsonium compounds), where S is sulfur (to provide a ternary sulfonium compound) and where X - may be hydroxide, alkoxide, bicarbonate, carbonate, formate, acetate, lactate, and other carboxylates derived from volatile organic carboxylic acids or the like. Such salts of carboxylic acids are effective to promote the low temperature cure provided that the carboxylic acid portions of the salt are volatile. The compositions of the present invention are stable at ambient temperature and must be heated to an elevated temperature in order to cause the cross-linking reaction to occur at an appreciable rate. Generally, an elevated temperature of about 200° F. (about 93° C.) or more is required to effectuate the cross-linking reaction at an appreciable rate. As used herein and in the claims, an "elevated" temperature is one which is sufficient to cure the deposited composition by causing the cross-linking reaction to occur at a desired rate, usually a rate sufficient to effectuate cure within a period of 1 hour or less. In many instances a pigment composition and various conventional additives such as antioxidants, surface active agents, coupling agents, flow control additives, and the like, can be included. The pigment composition may be of any conventional type, such as, one or more pigments such as iron oxides, lead oxides, strontium chromate, carbon black, titanium dioxide, talc, barium sulfate, cadmium yellow, cadmium red, chromic yellow, or the like. After deposition on a substrate, such as a steel panel, the coating composition is devolatilized and cured at elevated temperatures by any convenient method such as in baking ovens or with banks of infrared heat lamps or in microwave ovens. Curing can be obtained at temperatures in the range of from 120° C. to about 300° C., preferably from 150° C. to about 200° C. for from about 30 minutes at the lower temperatures to about 1 minute at the higher temperatures. DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples illustrate the compounds and compositions of the present invention. They are not to be construed as limiting the claims in any manner. All parts are by weight. EXAMPLE 1 2,4-Bis[N,N-bis[(2-hydroxyethoxycarbonylamino)-ethyl]amino]-6-chloro-s-triazine (TECT) (I) To 50 g water in a 3-neck flask equipped with stirrer and a thermometer, were added 9.2 g (0.05 m) of cyanuric chloride, dissolved in 50 g acetone below 10° C. To the white slurry of cyanuric chloride, 27.9 g of bis(2-hydroxyethyl) (iminodiethylene)biscarbamate (HEC), NH(CH 2 CH 2 NHCO 2 CH 2 CH 2 H) 2 dissolved in 50 g of water was added over a period of 15 minutes. During the addition, the reaction temperature was maintained below 12° C. After complete addition of HEC, the slurry turned into a clear solution. To this was added 10% caustic to maintain the reaction pH at about 7 and the reaction mixture was allowed to warm up to 25° C. At 25° C., as the reaction progressed, a white crystalline solid slowly separated out. After 4 hrs. at 25-35° C., the solids were separated by filtration, washed with water and recrystallized from ethanol. The product yield was 24 g and m.p. 174° C. The structure of the product was confirmed by nuclear magnetic resonance (nmr) and fast atomic bombardment (fab), mass spectrometry to be that of FORMULA I: ##STR17## EXAMPLE 2 Hexakis[2-(2-hydroxyethoxycarbonylamino)ethyl]melamine (HECM)(II) To 6.7 g of (I) (Example 1, TECT) were added 2.8 g HEC, 0.84 g sodium bicarbonate and 25 g ethylene glycol. The reaction mixture was then heated to 115° C. in an oil bath for 4 hours, after which most of the HEC had reacted with TECT as indicated by amine titration of the reaction mixture. Ethyelene glycol was distilled off under reduced pressure. The residue was poured into methanol. Separated solids were filtered and recrystallized from methanol. Yield 5.6 g (60% of theoretical), m.p. 192° C. The nmr and fab mass spectra confirmed the product to be of FORMULA II: ##STR18## EXAMPLE 3 Hexakis[2-(2-hydroxypropoxycarbonylamino)ethyl]melamine (HPCM) (III) As in Example 1, 9.2 g (0.05 m) of cyanuric chloride was slurried into water in a suitably equipped 3 neck flask. To the slurry was added 78 g (0.02 m) of bis(2-hydroxypropyl) (iminodiethylene)bis carbamate (HPC), an isomeric mixture of NH(CH 2 CH 2 NHCO 2 CH(CH 3 )CH 2 OH) 2 and NH(CH 2 CH 2 NHCO 2 CH 2 CH(CH 3 )OH) 2 , (80% by weight in isobutanol) below 10° C. After complete addition of HPC to the reaction mixture, the temperature of the mixture was allowed to rise to 25° C. A clear, pale yellow solution was obtained. The clear solution after several hours at 25° C. was treated with Dowex® 1×8 (OH - ) anion exchange resin to remove HCl. The HCl free solution was then stripped under reduced pressure to remove acetone and water. The water-free syrupy residue, 90 g, and 100 g of propylene glycol were heated on an oil bath to 115° C. for 4 hours. The total free amine in the mixture was 36 meq. The reaction mixture in methanol was treated first with Dowex® 1×8(OH - ) and subsequently with Dowex® 50W×8(H + ) ion exchange resins to remove Cl - and free HPC. After removal of methanol and ethylene glycol under reduced pressure a white solid product was obtained. Its structure was confirmed by spectroscopy to be of FORMULA III: ##STR19## wherein R 1 , R 2 and R 3 are --N(CH 2 CH 2 NHCO 2 CH(CH 3 )CH 2 OH) 2 or --N(CH 2 CH 2 NHCO 2 CH 2 CH(CH 3 )OH) 2 The product (III) as shown by the above formula was an isomeric mixture of compounds containing primary and secondary hydroxy groups. The yield was 32 g (64% of theory), and the melting point was 110-120° C. EXAMPLE 4 2,4-Bis[N,N-bis[(2-hydroxypropoxy carbonylaminoethyl)amino]-6-chloro-s-triazine (TPCT) (IV) In a suitably equipped 3-neck flask, 9.2 g (0.05 m) of cyanuric chloride solution in 50 g of acetone was slurried in 50 g of water below 10° C. To this was added slowly 38.8 g of HPC (80% in isobutanol) dissolved in 50 g of water below 10° C., maintaining temperature of the reaction mixture. At the complete addition of HPC, the reaction mixture turned into a clear, pale yellow solution. The batch temperature was allowed to rise while maintaining the pH of 6-7 by slow addition of 10% caustic solution to the batch. After completion of the reaction (after 3-4 hours at 25-30° C.) water was removed from the reaction mixture by azeotroping with n-butanol under reduced pressure. The separated sodium chloride was filtered off. The clear filtrate was vacuum stripped to remove butanol. After the removal of butanol, a syrupy product was obtained, which on long standing, solidified. The mass spectrum of the syrup product indicated it to be of FORMULA IV: ##STR20## wherein R 2 and R 3 are --N(CH 2 CH 2 NHCO 2 CH(CH 3 )CH 2 OH) 2 or --N(CH 2 CH 2 NHCO 2 CH 2 CH(CH 3 )OH) 2 (IV) The solidified product (TPCT), which is an isomeric mixture as shown by the above formula, was crystallized from acetone. The yield was 6 g and the melting point was 135-140° C. EXAMPLE 5 Reaction of FORMULA I (TECT) with Piperidine In a suitable equipped round bottom flask were charged 6.7 g of the product of Example 1 (TECT)(0.01 m), 0.85 g (0.01 m) of piperidine and 0.85 g of sodium bicarbonate and 25 g of ethylene glycol. The mixture was heated on an oil bath to 115° C. for 4 hours. The total free base after this reaction period was 1.4 meq. Ethylene glycol was removed by distillation under reduced pressure below 150° C. The resinous product was dissolved in methanol. The separated sodium chloride was filtered off and washed with small amounts of methanol. After removal of methanol from the reaction product, a glassy solid was obtained. Mass spectra of the product indicated it to be of FORMULA V: ##STR21## EXAMPLE 6 Reaction of FORMULA IV (TPCT) with Piperidine In a suitable equipped round bottom flask were charged 43.5 g (0.06 m) of the product of Example 4 (TPCT), 11.5 g (0.13 m) of piperidine, 5.43 g (0.06 m) of sodium bicarbonate, and 96 g of propylene glycol mono-methyl ether. The mixture was heated at 120° C. for 5 hours. Sodium chloride was separated from the product by filtration. Dowex® 50W×8(H+) ion exchange resin was added to the solution and stirred 30 minutes to remove excess amine. The resin beads were separated from the product by filtration. The propylene glycol mono-methyl ether was stripped from the product under vacuum at 110° C. The product was a resinous material. Mass spectra indicated the compound to be of Formula VI: ##STR22## wherein R 2 and R 3 are --N(CH 2 CH 2 NHCO 2 CH(CH 3 )CH 2 OH) 2 or --N(CH 2 CH 2 NHCO 2 CH 2 CH(CH 3 )OH) 2 (VI) EXAMPLE 7 Reaction of FORMULA IV (TPCT) with Dodecylamine In a reaction vessel were charged 16.6 g (0.02 m) of the product of Example 4 (TPCT), 8.5 g (0.04 m) of dodecylamine, 1.9 g (0.02 m) of sodium bicarbonate, and 50 g of propylene glycol monomethyl ether. The mixture was heated at 115° C. for 2.5 hours. Sodium chloride was separated from the product by filtration. Dowex® 1×8(OH-) ion exchange resin was added and the mixture was stirred 30 minutes to remove free chloride ions. The resin beads were filtered out and Dowex® 50W×8(H+) ion exchange resin was added. The mixture was stirred 30 minutes to remove excess amine and then the resin beads were removed by filtration. The propylene glycol monomethyl ether was stripped from the product under vacuum at 110° C. The product was resinous material. Mass spectra indicated the compound to be of FORMULA (VII): ##STR23## wherein R 1 and R 2 are --N(CH 2 CH 2 NHCO 2 CH(CH 3 )CH 2 OH) 2 or --N(CH 2 CH 2 NHCO 2 CH 2 CH(CH 3 )OH) 2 (VII) EXAMPLE 8 REACTION OF FORMULA I (TECT) WITH PIPERAZINE In a suitable equipped round bottom flask were charged 14.85 g (0.02 m) of the product of Example 1 (TECT), 0.987 g (0.01 m) of piperazine, 1.89 g (0.02 m) of sodium bicarbonate, and 53 g of propylene glycol mono-methyl ether. The mixture was heated at 115° C. for 5 hours. The propylene glycol monomethyl ether was stripped from the product under vacuum at 110° C. The solid product was washed with water to remove sodium chloride. The product was finally dried to remove water. Mass spectra indicated the product to be of FORMULA VIII: ##STR24## R 1 and R 2 are --N(CH 2 CH 2 NHCO 2 CH 2 CH 2 OH) 2 (VIII) EXAMPLE 9 REACTION OF FORMULA IV (TPCT) WITH PIPERAZINE In a suitably equipped round bottom flask were, charged 32.6 g (0.045 m) of the product of Example 4 (TPCT), 1.3 g (0.015 m) of piperazine, 3.8 g (0.045 m) of sodium bicarbonate, and 61 g of propylene glycol monomethyl ether. The mixture was heated at 115° C. for 4 hours. Sodium chloride and sodium bicarbonate were separated from the product by filtration. The propylene glycol monomethyl ether was stripped from the product under vacuum at 110° C. The product was a resinous material. Mass spectra confirmed the structure to be of FORMULA IX: ##STR25## wherein R 1 and R 2 are --N(CH 2 CH 2 NHCO 2 CH(CH 3 )CH 2 OH) 2 or --N(CH 2 CH 2 NHCO 2 CH 2 CH(CH 3 )OH) 2 (IX) EXAMPLE 10 Preparation of 2-Bis[N,N-bis[(2-hydroxypropoxy carbonylaminoethyl]-amino-4,6-dichloro-s-triazine (X) To a reaction vessel is added 15.6 g (0.05 m) of bis(2-hydroxypropyl)(iminodiethylene)bis carbamate dissolved in 50 g of N-butanol. To this solution is added 4.2 g of sodium bicarbonate. Then, at 0-5° C., is added slowly 9.2 g (0.05 m) of cyanuric chloride dissolved in 75 g of ethyl acetate. The reaction mixture is allowed to stir at 0-5° C. and progress of the reaction was monitored by thin layer chromatography (tlc). As soon as all the cyanuric chloride is converted to monosubstituted product, the reaction mixture is filtered and washed with ethyl acetate to separate sodium chloride from the filtrate. The product is isolated by removing ethyl acetate and n-butanol under reduced pressure. EXAMPLE 11 Preparation of 2-Bis[N,N-bis[(2-hydroxyethoxy carbonyl aminoethyl]amino]4,6-dichloro-s-triazine (XI) This compound is prepared by the same procedure as in Example 10 except that cyanuric chloride (0.05 m) is reacted with bis(2-hydroxyethyl)(iminodiethylene)biscarbamate (0.05 m). EXAMPLE 12 Preparation of 2,4-bis[N,N-bis[(2-hydroxypropoxy carbonyl aminoethyl]-amino]-6-di-n-butylamino-s-triazine (XII) In a suitably equipped round bottom flask were charged 21.75 g (0.03 m) of the product of Example 4 (TPCT), 4.65 g (0.036 m) of di-n-butylamine, 2.52 g (0.03 m) of sodium bicarbonate, and 200 g n-butanol. The mixture was heated to reflux (118-120° C.) for 4.5 hours. The reaction was followed by thin layer chromatography (tlc). The reaction was stopped when practically all of IV was converted to the product. The reaction mixture was filtered to remove sodium chloride. The trace amount of di-n-butyl amine was removed by Dowex® 50W×8(H+) ion exchange resin. After removal of n-butanol the product was recrystallized from ethyl acetate. Yield: 17 g (69% of theory) mp 125-130° C. N.m.r. of the product confirmed the structure as shown below. The product is soluble in common organic solvents used in coatings. ##STR26## wherein R 1 and R 2 are --N(CH 2 CH 2 NHCO 2 CH 2 (CH 3 )CH 2 OH 2 ) 2 or --N(CH 2 CH 2 NHCO 2 CH(CH 3 )OH) 2 (XII) EXAMPLE 13 Preparation of 2,4-bis[N,N-bis[(2-hydroxypropoxy carbonyl amino ethyl]-amino]-6-di-iso-butylamino-s-triazine (XIII) In a suitably equipped round bottom flask were charged 21.5 g (0.03 m) of the product of Example 4 (TPCT), 4.65 g (0.036 m) of diisobutylamine, 2.52 g (0.03 m) of sodium bicarbonate, and 60 g 2-propoxypropanol. The mixture was heated to reflux for 7 hours. tlc shows practically all product and only a trace amount of IV. The reaction mixture was worked up as in Example 12. After removal of solvent a sirupy product was obtained. On complete drying a glassy solid was obtained m.p., ˜55° C. The yield was quantitative. The n.m.r. confirmed the structure as shown below. The product is soluble in common organic solvents such as methyl ethyl ketone, toluene, ethyl acetate, n-butanol, etc. It is insoluble in water. ##STR27## wherein R 1 and R 2 are --N(CH 2 CH 2 NHCO 2 CH(CH 3 )CH 2 OH 2 ) 2 or --N(CH 2 CH 2 NHCO 2 CH 2 CH(CH 3 )OH) 2 (XIII) EXAMPLE 14 Preparation of 2-bis[N,N-bis[(2-hydroxy propoxy carbonyl aminoethyl]-amino]-4,6-dibutylamino-s-triazine (XIV) This compound is prepared in two steps. First the compound described in Example 10 is prepared without isolating it. Then, to this product 8.4 g NaHCO 3 , and 12.9 g (0.lm) of di-n-butylamine are added and the reaction temperature is raised slowly to 115° C., after distilling off ethyl acetate. The reaction temperature is maintained at 115° C. for several hours to complete the substitution of chlorine atoms by dibutylamine. After the reaction is complete, sodium chloride formed during the reaction is filtered off. After removal of n-butanol the desired product is obtained. EXAMPLE 15 Preparation of 2-bis[N,N-bis[(2-hydroxypropoxy carbonyl aminoethyl]-amino]-4,6-dianilino-s-triazine (XV) This compound is prepared by following the procedure of Example 14, but instead of di-n-butylamine, aniline (9.2 g, 0.lm) is used. EXAMPLE 16 Preparation of 2-bis[N,N-bis[(2-hydroxypropoxy carbonylaminoethyl]-amino-4-butylamino-6-anilino-s-triazine (XVI) To a suitably equipped 3-necked flask, are added 15.6 g (0.05 m) of bis(2-hydroxypropyl)(imino diethylene)bis carbamate dissolved in 50 g of n-butanol. To this solution are added slowly 9.2 g (0.05 m) of cyanuric chloride dissolved in 75 g of ethylacetate. The reaction mixture is allowed to stir at 0-5° C. and progress of the reaction is monitored by tlc. After all the cyanuric chloride is reacted to the mono substituted product, 8.4 g of sodium bicarbonate and 3.65 g (0.05 m) of n-butylamine are added. The reaction temperature is raised to 35-45° C. and maintained there until most of the n-butylamine has reacted. At this point 4.7 g (0.05 m) aniline are added and the reaction temperature raised to 115° C. after distilling out ethyl acetate. After about 5-6 hours, sodium chloride is filtered off. After removal of n-butanol and reaction work up and above-described product is obtained in high yields. ##STR28## wherein R 1 is --N(CH 2 CH 2 NHCO 2 CH(CH 3 )CH 2 OH) 2 or --N(CH 2 CH 2 NHCO 2 CH 2 CH(CH 3 )OH) 2 (XV) EXAMPLE 17 Transesterification of FORMULA III to Produce Crosslinker XVII In an autoclave were charged 100 g (0.1 m) of the compound of Example 3 (HPCM)(III), 225 g (3.0 m) of n-butanol, and 1.2 g of dibutyltindilaurate catalyst. The autoclave was heated in an oil bath on a magnetic stirrer hot plate to 155° C. The reaction mixture was kept in the oil bath at 155° C. for 5 hours. The pressure in the autoclave was about 40 psi. The resulting product mixture was a clear yellow solution. It was soluble in common organic solvents at room temperature. It was also miscible with commercially available acrylic resins and polyesters. The clear solution was concentrated to 45% solids. The proton n.m.r. of the product showed that about 40% of hydroxypropylcarbamate groups were transesterified with n-butanol. The average distribution of the hydroxypropylcarbamate to butylcarbamate was 2:3. The transesterification reaction is shown below: ##STR29## EXAMPLE 18 Preparation of Crosslinker XVIII In an autoclave were charged 100 g (0.lm) of the compound of Example 3 (HPCM)(III), 320 g (2.7 m) of 2-propoxy-propanol, and 1.2 g of dibutyltindilaurate catalyst. The autoclave was heated in an oil bath on a magnetic stirred hot plate to 155° C. The reaction mixture in the autoclave was stirrer with a magnetic stirrer. The reaction mixture was kept in the oil bath at 155° C. for 6 hours. After this period the resulting product mixture was a pale amber solution It was soluble in common organic solvents it was also misible with commercially available polyesters and acrylic resins such as Joncryl® 500 (S.C. Johnson and Son, Inc.). The proton n.m.r. of the product showed that about 50% of hydroxypropylcarbamate groups were transesterified with 2-propoxypropanol. The average distribution of the hydroxypropyl carbamate to 2-propoxypropyl carbamate was 1:1. The product solution was concentrated to 45.3% by partial removal of 2-propoxypropanol. EXAMPLE 19 Self-Crosslinked Melamine-Urethane Polymer Film 2.2 g of the reaction product of piperidine and TECT (Compound V from Example 5) was dissolved in n-butanol. To this butanol solution were added 2 drops of benzyltrimethylammonium hydroxide (40%) and a drop of 1% solution of fluorocarbon surfactant FC 431 in n-butanol. The clear, pale yellow blend was cast as a film on a zinc phosphate treated cold rolled steel panel and baked at 150° C. for 20 minutes. The resulting film was very hard and glass-like, and had excellent resistance to acetone. The film thickness was 0.6 mil, Knoop hardness was 37, pencil hardness was greater than 5H and it passed the 1/8" mandrel bend test. EXAMPLE 20 A hydroxy-functional acrylic resin was prepared by copolymerizing a blend of n-butyl acrylate (60 wt %), styrene (20 wt %), and 2-hydroxyethyl methacrylate (20 wt %), using dicumyl peroxide initiator and n-dodecyl mercaptan chain transfer agent. The polymerization was carried out in 2-ethoxyethanol at reflux temperature (135-140° C.). Ten grams of 75% solution of a hydroxy functional acrylic resin was blended with 2.5 g of crosslinker of FORMULA III (HPCM), 0.3 g tetrabutyl diacetoxy stannoxane catalyst and 5 g n-butanol. The blend was warmed to make it homogenous. The well-mixed homogenous blend was cast on a zinc phosphate treated cold rolled steel panel using #22 Wirecator®. The films were baked at 150° C. and 175° C. for 20 minutes respectively. The film properties are shown in Table 1. TABLE 1______________________________________Properties of Acrylic Coatings A B______________________________________Bake schedule 20'/150° C. 20'/175° C.Film thickness 0.8 mil 0.9 milPencil hardness 2B-B HB-FImpact resistance (Reverse) 80 in.lbs. 80 in.lbs.MEK resistance (Double Rub) 100+ 100+Humidity resistance (140° F.) Passes 2 wks. Passes 3 wks.______________________________________ EXAMPLE 21 Four formulations were prepared by blending a commercially available polyester resin Multron® 221-75 (Mobay), crosslinker FORMULA III (HPCM) and a tin catalyst. Amounts of each component are shown in Table 2. The 175° C. baked films obtained from formulation E and F were essentially crosslinked as indicated by MEK rubs. Films from formulations C and D required 200° C. bake to achieve crosslinking. Films from formulations E and F had 200°+ MEK rubs. These results show that tetrabutyl diacetoxy stanoxane (TBDAS) is a more effective catalyst than dibutyltin dilaurate (DBTL) in these formulations. TABLE 2______________________________________Properties of Polyester - HPCM Coatings C D E F______________________________________Multron ® 221-75 16 g 15 g 15 g 16 gCrosslinker III 4 5 5 4DTL 0.2 0.2 -- --TBDAS -- -- 0.2 0.2n-BuOH 8 8 8 8Bake Schedule175° C./20' No cure 35 175 100(MEK rubs)200°/20' 70 85 200+ 200+(MEK rubs)______________________________________ The results reported in Tables 1 and 2 demonstrate that the compound of FORMULA III (HPCM) functions as a cross-linker to cross-link acrylic and polyester thermoset resins with pendant hydroxy groups. The reduced cure response of the polyester resin versus that of the acrylic resin is due to the fact that the polyester resin has residual acid (acid number 10) while the acrylic resin is free of any acid (acid number 2). The presence of nonvolatile acid in the film results in retardation of cure rate of transesterification reaction required for cross-linking. EXAMPLE 22 Modification of FORMULA III (HCPM) for Use as Crosslinker For Cathodic Electro Coating (EC) Compositions 9.96 g (0.01 m) of HPCM (Example 3) and 65 g (0.05 m) of 2-ethylhexanol were heated together to 155-160° C. in the presence of 2 g of tetrabutyl diacetoxy stannoxane for 61/2 hours. After this period, 2-ethylhexanol was distilled off under reduced pressure at 150-160° C. A white creamy solid residue was obtained (17 g) which dissolved in n-butanol (4.7 g) to a clear amber colored solution. Mass Spectra of the product indicated the product mainly to be a mixture of the following: ##STR30## The product was insoluble in water and very hydrophobic. These properties make the product a suitable cross-linker for cathodic EC compositions. Similar hydrophobic cross-linkers can be prepared by oligomerization and by transesterification of FORMULA III (HPCM) with hydrophobic alcohols. Other hydrophobic s-triazine compounds with pendant hydroxyalkylcarbamate groups, carbamate groups or mixture of hydroxyalkyl carbamate groups can be used in cathodic electrocoating as crosslinking agents. The cross-linking ability of the product of this Example 22 is demonstrated in Example 23 by cross-linking a cationic resin suitable for cathodic electrocoating. EXAMPLE 23 Nine and three-tenths grams of a cationic resin (prepared according to U.S. Pat. No. 3,984,299, adduct C) was blended with 6 g of the product of Example 22 (50% solution) along with 0.1 g of dibutyltin dilaurate catalyst. The blend was cast on a steel panel and baked at 175° C./20'. The film after the bake had a film thickness of 1 mil; a pencil hardness of 3H; and a MEK rub resistance of 75-100. EXAMPLE 24 To show efficacy of crosslinking agents of FORMULAE XII, XIII, XVII, and XVIII, clear formulations were prepared using hydroxy functional acrylic and polyester resins as shown in Table 3. A formulation was also prepared with an acrylic resin and methylated melamine-formaldehyde resin, used widely in many industrial coatings (Control No. 7). TABLE 3__________________________________________________________________________Coating FormulationsFORMULATION 1 2 3 4 5 6 7COMPOSITION (this invention) (control)__________________________________________________________________________Acrylic Resin.sup.1 -- -- 3.6 7.6 10 9.3 57.2Joncryl ® 500.sup.2 3.3 -- -- -- -- -- --Cargill 5776.sup.3 -- 2.9 -- -- -- -- --Crosslinker XII -- 0.9 -- -- -- -- --Crosslinker XIII.sup.4 -- -- -- -- 3.4 4 --75% solutionCrosslinker XVII.sup.5 -- -- 1.65 4.2 -- -- --Crosslinker XVIII.sup.6 1.7 -- -- -- -- -- --Cymel ® 3037 -- -- -- -- -- -- 12.5TBDAS.sup.8 0.03 0.03 0.036 0.1 0.1 0.1 --n-DDBSA.sup.9 -- -- -- -- -- -- 0.3Resin/Crosslinker 77/23 75/25 75/25 75/25 75/25 70/30 75/25Ratio__________________________________________________________________________ .sup.1 Acrylic polymer prepared by copolymerizing nbutyl acrylate (50 wt %), styrene (30 wt %), and 2hydroxy ethyl methacrylate (20%). Hydroxy No. 94, 75% solution in 2propoxypropanol. .sup.2 A commercially available resin from Johnson Wax. .sup.3 A commercially available polyester resin from Cargill. .sup.4 75% solution in 2methoxypropanol. .sup.5 45% solution in nbutanol. .sup.6 48.5% solution in 2propoxypropanol. .sup.7 methylated melamineformaldehyde resin available commercially from American Cyanamid Company (Control). .sup.8 Tetrabutyl diacetoxy stannoxane. .sup.9 ndodecylbenzenesulfonic acid, 70% solution. The formulations were cast on zinc phosphate pretreated steel panels and the films were baked at 150° C. and 175° C. respectively. In case of formulation 2, the films were cast on aluminium panels and baked at 260° C. for 60 seconds, commonly used in coil coating. The results of testing are set forth in Table 4: TABLE 4__________________________________________________________________________FILM PROPERTIESFORMULATION 1 2* 3 4 5 6 7__________________________________________________________________________Bake Schedule 175 260 150 175 150 175 150 175 150 175 150 175°C./min. 20 20 20 20 20 20 20 20 20 20 20 20Film Thickness 0.7 0.6 1.0 0.7 0.8 0.8 0.7 0.6 0.7 0.5 1.0 1.0(mils)Knoop Hardness 11.8 -- 11.2 11.0 4.8 11.5 8.6 11.0 8.3 13.2 10.9 12.6Pencil Hardness 2H 2H F-H H F 2H H 2H H 2H H HHumidityResistance 3 wks -- -- -- -- -- 3 wks 3 wks 3 wks 3 wks 3 wks 3 wks(140° F.) N.C.** -- -- -- -- -- N.C. N.C. N.C. N.C. 8B 7BSalt SprayResistance 10; -- -- -- -- -- 6; 9; 6; 9; 5; 5;(240 hrs) 0 mm 3 mm 0 mm 2 mm 0 mm 10 mm 10 mmMEK Double Rub 200+ 200+ 200+ 180 200+ 200+ 200+ 200+ 200+ 200+ 200+ 200+T-Bend T3 passesImpact (Rev.) 0-10 50 50 50 50 30-40 50 50 50 50 0-10 0-10in.lbs.__________________________________________________________________________ *Films were cast on aluminum panels Alodine ® 1200s **N.C. no corrosion Film properties in Table 4 show that crosslinked films obtained by utilizing crosslinking agents of FORMULAE XII, XIII, XVII and XVIII have good solvent resistance, excellent hardness, and good flexibility. The humidity and salt spray resistance of these films is also superior to the films obtained from the acrylic-methylated melamine-formaldehyde crosslinking agent based control formulation. The other advantage is that the formulations are formaldehyde free. Experiments have also shown that, in unpigmented coatings, crosslinked films obtained by using the novel urethane-functional s-triazine crosslinker XVII had better corrosion resistance, humidity resistance and better post-forming properties as compared with films obtained with commercially available alkylated melamine formaldehyde crosslinkers as in control formulation 7. EXAMPLE 25 Transesterification of FORMULA III (HPCM) with 2-Butoxyethanol 50 g (0.05 m) of HPCM (III, Example 3) and 295 g of 2-butoxyethanol were heated to reflux at 160° C. in the presence of 5 g of tetrabutyl diacetoxy stannoxane for four hours. The excess 2-butoxyethanol and propylene glycol formed during the reaction were removed under reduced pressure. The viscous residue was dissolved in methanol. On standing, the tin catalyst separated from the solution. It was filtered off and an amber colored residue was dissolved in n-butanol, solids, content, 50.4%. The product was insoluble in water. The expected structure of the product having pendant 2-butoxyethylcarbamate groups is shown below. The infrared spectrum was consistent with a product of FORMULA XXV. ##STR31## R 1 and R 3 are --N(CH 2 CH 2 NHCO 2 CH 2 CH 2 OC 4 H 9 ) 2 and R 2 is --N(CH 2 CH 2 NHCO 2 CH(CH 3 )CH 2 OH) 2 (XXV) EXAMPLE 26 Preparation of Cationic Acrylic Polymer and Cross-linking with Compound (XXV) A cationic acrylic polymer with pendant hydroxy groups (Hydroxy number 90) was prepared according to U.S. Pat. No. 4,026,855 (1977), described as cationic polymeric material E in column 8. There were three minor changes (i) instead of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate was utilized; (ii) the monomer-acrylic acid ester of methoxy polyethylenoxyglycol (55) was eliminated; and (iii) the final resin solids were 76%. Thirty-five grams of the cationic acrylic resin, 23 g of crosslinking agent of Example 25, 12.5 g rutile titanium dioxide OR®600, 0.5 g acetic acid, and 0.5 g of tetrabutyl diacetoxy stannoxane were blended together on high speed stirrer to obtain good dispersion and wetting of the pigment. To this was slowly added deionized water to make up the final volume of the paint dispersion to 500 ml. The final paint solids were 10%, the bath pH was 4.9 and bath conductivity was 440 Ohm -1 cm -1 . The bath was allowed to age overnight at room temperature. Next day phosphate coated steel panels (BO 100®) were electrocoated using stainless steel anode. The deposition characteristics and film properties after baking for 20 minutes are shown in Table 6. TABLE 5__________________________________________________________________________Electrodeposited Cross-linked Acrylic CoatingsDeposition Time (Depositing) Bake Film Thickness Knoop Impact (rev.) MEK RubVoltage(v) (secs) Temp.°C. (mil) Hardness in.lb. Resistance__________________________________________________________________________100 60 150 0.62 11.2 -- 200+100 90 150 0.6 11.2 -- 200+100 90 175 0.6 12.0 -- 200+200 60 150 1.0 6.8 40+ 200+200 60 175 1.0 12.5 20-30 200+250 30 150 1.0 6.9 40+ 200+250 30 175 1.0 12.6 20-30 200+__________________________________________________________________________ The results in Table 6 show that the bath had good electrodeposition characteristics and films were completely crosslinked at 150° C. in 20 minutes. However, the electrocoating bath showed signs of instability after two weeks of aging at room temperature. EXAMPLE 27 A coating composition is prepared comprising an acrylic resin which is a copolymer of n-butyl acrylate, styrene and 2-hydroxyethyl methacrylate in 2-ethoxyethanol (solids 75%, hydroxy number, 85), 18.7 g, Compound of FORMULA III (HPCM), (40% in cellosolve), 15 g, and 0.2 g of tetrabutyl diacetoxy stannoxane catalyst were blended together to form a clear resinous solution. Films were cast onto phosphate treated steel panels and baked at 150° C. for 20 minutes. The films were completely cured as indicated by resistance to 200+ MEK rubs. EXAMPLE 28 A coating composition is prepared comprising the reaction product of 1 mole of bisphenol A and 6 moles of ethylene oxide (hydroxyl number 212, Dow Chemical Co. XD-8025 polyol), 10 g, compound of FORMULA III, (HPCM) Example 3, 6 g, tetrabutyl diacetoxy stannoxane catalyst, 0.2 g, butanol, 5 g, water 2 g, blended together until clear and homogeneous. The solution was cast onto phosphate treated steel panels and baked at 150° C. for 20 minutes. The film thickness was 0.7 mil; pencil hardness FH; Knoop hardness was 5, reverse impact resistance was 80 + in.lbs.; humidity resistance at 60° C. was 21+ days; and the MEK double rub test was 200+. The above-mentioned patents and publications are incorporated herein by reference. Many variations of this invention will suggest themselves to those skilled in this art in light of the above, detailed description. For example, instead of hydroxyfunctional polyesters and polyacrylates, epoxy resins, such as the polyglycidylethers of bisphenol A and the reaction products thereof with amines and ammonia can be used. Or, for example, the s-triazine cross-linkers of this invention may be used in other types of coating compositions, such as high solids coatings, cathodic electrocoatings and powder coatings formulations. They may also be used in polyurethane RIM (reaction injection molding) and foam formulations as one of the polyol components. All such obvious modifications are within the full intended scope of the appended claims.

Novel s-triazine compounds containing at least one N,N-bis(alkoxy or hydroxyalkoxy-carbonyl-amino C 2 -C 10 alkyl) amino substituent function in self-condensation and as cross-linkers for compounds containing active hydrogen groups. The compositions cure to coatings with excellent properties, especially corrosion resistance, humidity resistance, abrasion resistance and flexibility. The coatings have excellent exterior durability.

CROSS REFERENCE TO RELATED APPLICATION This application is a continuation application claiming priority to Ser. No. 12/022,636 filed Jan. 30, 2008, status allowed. TECHNICAL FIELD Embodiments are generally related to data-processing systems and methods. Embodiments also relate in general to the field of computers and similar technologies, and in particular to software and hardware components utilized in this field. In addition, embodiments relate to user input devices, such as keyboards, keypads, and so forth. BACKGROUND OF THE INVENTION With the development of compacting mobile computing technology, such as PDA (Personal Digital Assistant) devices, cellular telephones, portable media players, and so forth, current mobile devices are equipped with various functions, such as internet browsing, sending emails, camera, or games. As the functions of the mobile computing devices expand, the input interface becomes a critical issue. For example, the dimensions of current mobile devices tend to be minimized, and therefore the input interface is limited to number keyboards only or even several function keys. While the user intends to enter various alphabetic and numerical functions, such as letters, numbers, symbols, emoticons, etc., the only available approach is to enter via those number keyboards. Usually, one particular number key will represent several alphabets, and the user has to select the desired alphabet, which is an inefficient and time-consuming process often involving entering data into an options screen to change back and forth among the alphabets. Moreover, current mobile computing devices are often provided, for example, with gaming options and other applications such as streaming video and interactive texting. The keyboard configuration required for game playing, for example, is usually different from that of the conventional mobile computing device. The user, however, will also be restricted to the current available number keyboards while playing the game or utilizing an application via the mobile computing device, which significantly discourages the user from continued use of the application. Additionally, user input areas for small portable devices such as cell phones, PDAs and media devices are inefficient and prone to input error. For most mobile devices, a standard QWERTY keyboard apparatus (virtual or physical) can be used for input. Such a keyboard was designed for two handed input with spacing between keys matching that of spacing between human fingers. Various layouts with small keys or multiple displays have been implemented in small devices; however, these are usually adaptations of the QWERTY keyboard layout and as such not optimized for input with less than two hands. The optimization of keyboard layout for mobile devices should take into account research into the functioning of the human eye and human information processing. The following except is offered as a reference: “From physiological studies we know several basic facts about how the eye processes information and about the physical constraints that limit how this information is presented to the brain. During a fixation, the eye has access to three regions for viewing information: the foveal, parafoveal, and peripheral. The foveal region is the area that we think of as being in focus and includes 2 degrees of visual angle around the point of fixation, where 1 degree is equal to three or four letters (thus, six to eight letters are in focus). The parafoveal region extends to about 15 to 20 letters, and the peripheral region includes everything in the visual field beyond the parafoveal region. The fovea is concerned with processing detail, with anything beyond producing a marked drop in acuity; words presented to locations removed from the fovea are more difficult to identify” (Rayner & Sereno, 1994). A copy of the unabridged article is available at the following website as a reference: http://www.readingonline.org/research/eyemove.html Most, if not all, input apparatuses for small devices are variations of the standard keyboard or the number pad. These input apparatuses perform poorly when operated with one or two fingers as required by space constrained mobile devices. Circular and semi-circular inputs apparatuses are known in the art; however these apparatuses are designed for two finger or greater input and lack the dynamic rearrangement features required for efficient input on mobile devices. Therefore, there is a need for an improved mobile computing input interface that a user can utilize more conveniently. There is also a need for an improved input interface that facilitates the minimization of the mobile computing device. It is believed that the embodiments described in greater detail herein offer a solution to these current drawbacks. BRIEF SUMMARY The following summary is provided to facilitate an understanding of some of the innovative features unique to the present invention and is not intended to be a full description. A full appreciation of the various aspects of the embodiments disclosed herein can be gained by taking the entire specification, claims, drawings, and abstract as a whole. It is, therefore, one aspect of the present invention to provide for an improved data-processing method, system and computer-usable medium. It is another aspect of the present invention to provide for a method, system and computer-usable medium for providing a virtual self-adapting keyboard. It is a further aspect of the present invention to provide for a method, system and computer-usable medium for providing a circular keyboard for use with small input devices. The aforementioned aspects and other objectives and advantages can now be achieved as described herein. A method, apparatus and computer-usable medium are described herein for implementing virtual keyboards for use with small input devices. A circular keyboard can be graphically displayed, in response to a user input by a user via a small input device. A circular and centrally located key can be graphically positioned and displayed within the center of the circular keyboard, wherein character keys radiate outward from the circular and centrally located key (i.e., the “central key”) Character keys that are most commonly utilized by the user are preferably located closer to the circular and centrally located key within the circular keyboard. Character keys least commonly utilized by the user are preferably located at the edges of the keyboard, thereby permitting the circular keyboard to function as a self-adapting virtual keyboard for use with small input devices based on the usage of the keyboard by the user. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention. FIG. 1 illustrates a schematic view of a computer system in which the present invention may be embodied; FIG. 2 illustrates a schematic view of a software system including an operating system, application software, and a user interface for carrying out the present invention; FIG. 3 depicts a graphical representation of a network of data processing systems in which aspects of the present invention may be implemented; FIG. 4 illustrates a virtual keyboard apparatus that can be adapted for use with a small input device in order to improve the speed and accuracy of user input to such a small input device, in accordance with a preferred embodiment; FIG. 5 illustrates a small input device adapted for use with the virtual keyboard apparatus depicted in FIG. 4 , wherein the small input device includes a display screen and a rigid shell in accordance with a preferred embodiment; and FIGS. 6, 7, and 8 respectively illustrate flow charts depicting methods for implementing the virtual keyboard apparatus of FIG. 4 , in accordance with a preferred embodiment. DETAILED DESCRIPTION The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment and are not intended to limit the scope of such embodiments. FIGS. 1-3 are provided as exemplary diagrams of data processing environments in which embodiments of the present invention may be implemented. It should be appreciated that FIGS. 1-3 are only exemplary and are not intended to assert or imply any limitation with regard to the environments in which aspects or embodiments of the present invention may be implemented. Many modifications to the depicted environments may be made without departing from the spirit and scope of the present invention. As depicted in FIG. 1 , the present invention may be embodied in the context of a data-processing apparatus 100 comprising a central processor 101 , a main memory 102 , an input/output controller 103 , a keyboard 104 , a pointing device 105 (e.g., mouse, track ball, pen device, or the like), a display device 106 , and a mass storage 107 (e.g., hard disk). Additional input/output devices, such as a printing device 108 , may be included in the data-processing apparatus 100 as desired. As illustrated, the various components of the data-processing apparatus 100 communicate through a system bus 110 or similar architecture. It can be appreciated that data-processing apparatus 100 may implemented in the context, a desktop computer, computer workstation, a server, a laptop computer, and any number of small input devices, such as mobile computing devices, including cellular telephones, PDA (Personal Digital Assistant), portable medial players, and so forth. Illustrated in FIG. 2 , a computer software system 150 is provided for directing the operation of the data-processing apparatus 100 . Software system 150 , which is stored in main memory 102 and on mass storage 107 , generally includes a kernel or operating system 151 and a shell or interface 153 . One or more application programs, such as application software 152 , may be “loaded” (i.e., transferred from mass storage 107 into main memory 102 ) for execution by the data-processing apparatus 100 . The data-processing apparatus 100 receives user commands and data through user interface 153 ; these inputs may then be acted upon by the data-processing apparatus 100 in accordance with instructions from operating module 151 and/or application module 152 . The interface 153 , which is preferably a graphical user interface (GUI), also serves to display results, whereupon the user may supply additional inputs or terminate the session. In an embodiment, operating system 151 and interface 153 can be implemented in the context of a “Windows” system or another type of operation system such as, for example, Linux, etc. Application module 152 , on the other hand, can include instructions, such as the various operations described herein with respect to the various components and modules described herein, such as, for example, the method 600 depicted in FIG. 6 . FIG. 3 depicts a graphical representation of a network of data processing systems in which aspects of the present invention may be implemented. Network data processing system 300 is a network of computers in which embodiments of the present invention may be implemented. Network data processing system 300 contains network 302 , which is the medium used to provide communications links between various devices and computers connected together within network data processing apparatus 100 . Network 302 may include connections, such as wire, wireless communication links, or fiber optic cables. In the depicted example, server 304 and server 306 connect to network 302 along with storage unit 308 . In addition, clients 310 , 312 , and 314 connect to network 302 . These clients 310 , 312 , and 314 may be, for example, personal computers or network computers. Data-processing apparatus 100 depicted in FIG. 1 can be, for example, a client such as client 310 , 312 , and/or 314 . Thus, clients 310 , 312 , 314 , can be implemented as devices such as personal computers, computer workstations, PDA's, cell phones, portable media players, and so forth. Alternatively, data-processing apparatus 100 can be implemented as a server, such as servers 304 and/or 306 , depending upon design considerations. In the depicted example, server 304 provides data, such as boot files, operating system images, and applications to clients 310 , 312 , and 314 . Clients 310 , 312 , and 314 are clients to server 304 in this example. Network data processing system 300 may include additional servers, clients, and other devices not shown. Specifically, clients may connect to any member of a network of servers which provide equivalent content. In the depicted example, network data processing system 300 can constitute the Internet with network 302 representing a worldwide collection of networks and gateways that use the Transmission Control Protocol/Internet Protocol (TCP/IP) suite of protocols to communicate with one another. At the heart of the Internet is a backbone of high-speed data communication lines between major nodes or host computers, consisting of thousands of commercial, government, educational and other computer systems that route data and messages. Of course, network data processing system 300 also may be implemented as a number of different types of networks, such as for example, an intranet, a local area network (LAN), or a wide area network (WAN). Network 300 can also be implemented in the context of a wireless network, such as a cellular telephone network, Wi-Fi network, and so forth. The configurations depicted in FIGS. 1-3 are intended to serve as an example, and not as an architectural limitation for different embodiments of the present invention. The following description is presented with respect to embodiments of the present invention, which can be embodied in the context of a data-processing system such as data-processing apparatus 100 , computer software system 150 and data processing system 300 and network 302 depicted respectively FIGS. 1-3 . The present invention, however, is not limited to any particular application or any particular environment. Instead, those skilled in the art will find that the system and methods of the present invention may be advantageously applied to a variety of system and application software, including database management systems, word processors, and the like. Moreover, the present invention may be embodied on a variety of different platforms, including Macintosh, UNIX, LINUX, and the like. Therefore, the description of the exemplary embodiments which follows is for purposes of illustration and not considered a limitation. FIG. 4 illustrates a virtual keyboard apparatus 400 that can be adapted for use with a small input device (e.g., input device 500 depicted in FIG. 5 ) in order to improve the speed and accuracy of user input to such a small input device, in accordance with a preferred embodiment. FIG. 5 illustrates a small input device 500 adapted for use with the virtual keyboard apparatus 400 , and including a display screen 504 and a rigid shell 502 in accordance with a preferred embodiment. Note that in FIGS. 4-5 , identical or similar parts or elements are generally indicated by identical reference numerals. Note that display screen 504 is analogous to the display device 106 depicted in FIG. 1 , and the small input device 500 is analogous to the data-processing apparatus 100 depicted in FIG. 1 , albeit on a smaller scale. It can be appreciated that the display screen 504 (and analogous display device 106 ) can be implemented as a touch screen display. The virtual keyboard apparatus 400 can be implemented as a keyboard displayed on a small touch screen, a thumbstick operated keyboard with an associated visual display. The virtual keyboard apparatus 400 can be alternatively implemented in the context of keys with the ability to display characters (e.g., using known OLE technology or another method). Virtual keyboard apparatus 400 can be implemented with a substantially circular keypad 401 , having keys such as number keys 1, 2, 3, etc. and letter keys A, B, C, D, etc., along with keys providing other characters such as colon, semi-colon, period, plus and minus signs, and so on. A centrally located circular central key 410 can be implemented at the center of the circular keypad 401 with character keys radiating from the central key 410 . The central key 410 may be, for example, a key such as a space key, an enter key, or another type of preferred key. In the embodiment disclosed herein, a space key is shown as the central key 410 . In other embodiments, however, the central key 410 may be another type of key, such as, for example, an enter key. The most commonly utilized characters can be placed closest to the central key 410 and the least commonly used characters positioned on the edge of the circular keypad 401 forming a part of the overall virtual keyboard apparatus 400 . Examples of such least commonly utilized keys, include, for example, shift key 402 , delete key 404 , enter key 406 , and caps lock key 408 . For devices that utilize a display and thumbstick (or button) for input, a cursor can be programmed to return to the central key 410 after each user input. The virtual keyboard apparatus 400 is therefore optimized for single finger input by placing the keys most commonly used around a central point (e.g., central key 410 ) and placing the keys used less often further out from the center. In addition, this virtual keyboard apparatus 400 may modify the layout by relocating keys based on usage patterns to optimize key placement for frequently used keys. Such adaptive measures enable the user to input text on small devices faster than current known input apparatus. A circular presentation for smaller key layouts is advantageous due to the way the human eye sees information. It is known that the human eye focuses on a singular point and darts around that point filling in background information. Standard keyboard layouts such as QWERTY and Dvorak require memorization for maximum efficiency. Once a keyboard becomes smaller than the hand, however, this system is inefficient and even with memorization most users must look at the keys to use them. By organizing the keyboard such that the most common keys are arranged circularly around a point, memorization becomes unnecessary since the eye can find the keys quickly, and the distance traveled to any key is less than in known layouts. Since most users must look at smaller device keyboards to quickly input text the benefits of memorization are lessened. Additional advantages of this approach include the adaptability for both different languages and optimization for users that operate keyboards or communicate differently from the majority of known users. Further advantages of the virtual keyboard apparatus 400 exist for task oriented input tasks, such as interacting with HTML by leveraging current and future display technology to dynamically modify the keyboard layout and optimally placing keys based on the user's current input type. Most handheld devices do not conform to the rectangular shape of the standard keyboard, yet they implement a standard keyboard layout for input. This prevents optimization of both ergonomics, aesthetics and may reduce screen space for entered text. The virtual keyboard apparatus 400 , on the other hand, can fit to almost any proportion or device design and function. The virtual keyboard apparatus 400 is likely of most value to users who do not memorize keyboard layouts and do not input on virtual devices with regularity. Such users likely include mobile device “Luddites” with a limited typing ability and who “hunt and peck” when typing. It is known that the human eye focuses on a singular point and fills in information around that point by rapidly scanning and processing information close to that point. Virtual keyboard apparatus 400 thus represents a significant enhancement over the standard layout of keys. Improved efficiency results from a keyboard layout that may be rapidly processed by the human eye. By placing the keys most needed around the central point on the keyboard, the eye may locate a needed key faster than traditional keyboard layouts. FIGS. 6, 7, and 8 respectively illustrate a flow chart of operations depicting methods 600 , 601 , and 603 for implementing the virtual keyboard apparatus 400 , in accordance with a preferred embodiment. Note that methods 600 , 601 and 603 can be implemented in the context of or in association with a computer-useable data storage medium that contains a program product. The methods 600 , 601 , and 603 depicted in FIGS. 6, 7 and 8 can also be implemented in a computer-usable data storage medium containing a program product. Programs defining functions of the present invention can be delivered to a data storage system or a computer system via a variety of data storage media, which include, without limitation, non-writable data storage media (e.g., CD-ROM), writable data storage media (e.g., hard disk drive, read/write CD-ROM, optical media), and system memory such as but not limited to Random Access Memory (RAM) It should be understood, therefore, that such data storage media when storage computer readable instructions that direct method functions in the present invention, represent alternative embodiments of the present invention. Further, it is understood that the present invention may be implemented by a system having means in the form of hardware, software, or a combination of software and hardware as described herein or their equivalent. Thus, the methods 600 , 601 and 603 described herein can be deployed as process software in the context of a computer system or data-processing system as that depicted in FIGS. 1-3 and the virtual keyboard apparatus 400 and small input device 500 respectively illustrated in FIG. 4-5 . A preferred implementation of methods 600 , 601 and 603 generally includes two key areas for providing the virtual keyboard apparatus 400 described above. The first area involves operations generally required for keyboard layout. Such operations can include, but are not limited, to layout and application specific layout operations. The second area for providing the virtual keyboard apparatus 400 involves keyboard optimization. Thus, as indicated at block 602 , the process begins. Keyboard Layout Configuration As indicated at block 604 , upon keyboard invocation (e.g., touch screen), an operation can be initiated in which keys are placed on the screen as previously described based on a particular default layout, as indicated thereafter at block 606 . If the user has performed manual augmentations to the layout, as illustrated at block 608 , those settings are retained as indicated at block 610 , and the layout is affected accordingly and the operations continue. If the user had not performed manual augmentations to the layout then the process continues without such manual augmentations. Additionally, if the keyboard optimization component has modified the layout, as depicted at block 612 , those settings can be retained and keys laid out according to the optimization component as indicated at block 614 . The process then continues, as indicated by continuation block 616 . Embodiments may vary, but in general user requested augmentations should take precedence over automatic keyboard optimizations. A user may opt to disable optimization mutations on a per application basis and may still manually configure the key layout. A user may also desire to disable the optimization feature in several applications. For example, in a gaming application the user may only need a limited number of keys and expect certain keys to be in specific locations for input. Layout After acquiring the proper configuration, the keys of virtual keyboard apparatus 400 can be located in a circular fashion radiating outward from the central space button or key 410 as depicted at block 618 in FIG. 7 . Unless prevented by user augmentation, the most commonly used keys are placed closest to the center and the less commonly used keys are placed towards the edge of the keyboard as indicated at block 620 . Embodiments may vary, but in the preferred embodiment, the shift and other modifier keys are preferably placed in the corners as indicated at block 622 and as described earlier. Following the operation depicted at block 622 , an operation can be processed for determining if a touch screen is being utilized as indicated at block 624 . In touch screen devices with one screen for input and display, when a keyboard is required, the keyboard can be rendered onto the screen as indicated thereafter at block 626 , leaving enough room for textual display and the keys activated for textual input. Application Specific Layout Each application may have a specific layout. For example, a portable HTML editing program may include a different optimal key layout compared to that of a chat client. In the preferred embodiment, as the user switches applications the keyboard layout may switch to an optimized layout for that application as indicated respectively at blocks 628 and 630 . The user may, however, modify the layout for individual applications and the optimization component may optimize the layouts for each application. The process then continues, as indicated at block 632 Keyboard Optimization Keyboard optimization is illustrated by the method 603 depicted in FIG. 8 . As the user enters text, their key usage can be recorded and placed in a data storage location as indicated at block 634 . Keystroke analytics for each application can be used to derive the individual user's most used keys for each potential application specific keyboard layout as depicted at blocks 636 and 638 . The analytics may vary by embodiments, but most embodiments should detect the most frequently used keys, and the most frequently used key combinations as illustrated thereafter at block 640 . Keys and key combinations used more often should be placed closer to the center of the keyboard as described at block 642 . For example, a common key combination in a document writing program may be “t-h-e”, and as such those keys should be placed close to the center of the keyboard. In the preferred embodiment a user may enable or disabled the keyboard optimization component. The process can then terminate, as depicted at block 644 . It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.

A method, apparatus and computer-usable medium for implementing a virtual keyboard for use with small input devices. A circular keyboard can be graphically displayed, in response to a user input by a user via a small input device. A circular and centrally located key can be graphically located and displayed within the center of the circular keyboard, wherein character keys radiate outward from the centrally located key (i.e., the “central key”). Character keys that are most commonly utilized by the user are preferably located closed to the circular and centrally located key within the circular keyboard. Character keys least commonly utilized by the user are preferably located at the edges of the keyboard, thereby permitting the circular keyboard to function as a self-adapting virtual keyboard for use with small input devices based on the usage of the keyboard by the user.

BACKGROUND OF THE INVENTION 1. Technical Field The present invention relates to an improved data processing system and, in particular, to a method and system for data processing system reliability, and more specifically, for digital logic testing. 2. Description of Related Art As computers become more sophisticated, diagnostic and repair processes have become more complicated and require more time to complete. A service engineer may “chase” errors through lengthy diagnostic procedures in an attempt to locate one or more components that may be causing errors within the computer. For example, a diagnostic procedure may indicate an installed component or field replaceable unit (FRU) that is a likely candidate for the error, and the installed FRU may be replaced with a new FRU. The reported problem may be considered resolved at that point. If, after further testing of the previously installed FRU, the FRU is later determined to be reliable, the original problem has not actually been resolved and may remain unresolved until the next error is reported. In addition to paying for unnecessary components, a business must also pay for the recurring labor costs of the service engineer and lost productivity of the user of the error-prone system. Diagnosing errors during initial program load (IPL) is especially difficult because the operating system, which may contain sophisticated error logging functions, has not yet been loaded at that stage of system initialization, and the IPL code is purposefully devoid of many diagnostic functions in order to keep the IPL code efficient. Many computer systems employ chipsets designed with built-in self-tests (BISTs). The BISTs are dedicated test circuits integrated with other circuitry on a chip. During power-on reset (POR) of the system, POR BISTs automatically start and complete within a few seconds. As a result, a bit signature, or binary data pattern, is generated by the BIST. The IPL code reads the POR BIST signatures and compares the generated BIST signatures with predetermined signatures stored in the IPL code during code compilation, i.e. hardcoded into the IPL code. In addition to the POR BIST, the IPL code may initiate logical BISTs (LBISTs) or array BISTs (ABISTs) and verify their signatures. A problem may arise when there is a need to update one of the system chipsets with a newer version. When a new chipset is deployed, any IPL code containing associated BIST signatures must be updated to reflect the BIST signatures for the new chips. For most systems, the IPL code is stored in a flash module on the native I/O (NIO) planar. If there is a problem during the flash update of the IPL code that corrupts the IPL code, then the NIO planar must be replaced. If the chipset that needs to be upgraded or parts of the chipset that become defective are on different planars then the NIO planar is on a different planar than the NIO planar, then multiple planars may be replaced. In either case, replacement of a flash module results in increased costs and downtimes. Therefore, it would be advantageous to provide a method and apparatus for efficiently storing BIST signatures within a data processing system other than in the IPL module. SUMMARY OF THE INVENTION A method and apparatus for storing and using chipset built-in self-test (BIST) signatures is provided. A BIST for a chip in a data processing system may be initiated by a power-on-reset in the data processing system. The BIST signature generated during the BIST is compared with a predetermined BIST signature stored in a vital products data (VPD) module associated with the chip is read. A difference between the generated BIST signature and the predetermined BIST signature is then reported. BRIEF DESCRIPTION OF THE DRAWINGS The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: FIG. 1 is a pictorial representation depicting a data processing system in which the present invention may be implemented; FIG. 2A is a block diagram depicting a typical organization of internal components in a data processing system; FIG. 2B is a block diagram depicting an organization of internal components in a data processing system in accordance with a preferred embodiment of the present invention; and FIG. 3 is a flowchart depicting a process by which IPL code verifies BIST signatures in accordance with a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference now to FIG. 1, a pictorial representation depicts a data processing system in which the present invention may be implemented. A computer 100 is depicted, which includes a system unit 110 , a video display terminal 102 , a keyboard 104 , storage devices 108 , which may include floppy drives and other types of permanent and removable storage media, and mouse 106 . Additional input devices may be included with computer 100 . Computer 100 can be implemented using any suitable computer, for example, an IBM RISC/System 6000 system, a product of International Business Machines Corporation in Armonk, N.Y., running the Advanced Interactive Executive (AIX) operating system, also a product of IBM. Although the depicted representation shows a server-type computer, other embodiments of the present invention may be implemented in other types of data processing systems, such as workstations, network computers, Web-based television set-top boxes, Internet appliances, etc. Computer 100 also preferably includes a graphical user interface that may be implemented by means of system software residing in computer readable media in operation within computer 100 . FIG. 1 is intended as an example and not as an architectural limitation for the present invention. With reference now to FIG. 2A, a block diagram depicts a typical organization of internal components in a data processing system. Data processing system 200 employs a variety of bus structures and protocols. Although the depicted example employs a PCI bus, an ISA bus, a 6XX bus, and an inter-integrated circuit (I 2 C) bus, other bus architectures and protocols may be used. I 2 C is a simple two wire serial communications bus that employs an open collector to dot-and several ICs onto a bus. The 2 signals are serial clock line (SCL) and serial data line (SDL). This technology is patented by Philips Semiconductor. Processor card 201 contains processor 202 , L2 cache 203 , and vital product data module (VPD) 204 that are connected to 6XX bus 205 . System 200 may contain a plurality of processor cards. Processor card 206 contains processor 207 , L2 cache 208 , and VPD module 209 . 6XX bus 205 supports system planar 210 that contains 6XX bridge 211 and memory controller/cache 212 that supports memory card 213 . System planar 210 also has a unique vital product data module, VPD 214 . Memory card 213 contains local memory 214 consisting of a plurality of dual in-line memory modules (DIMMs) 215 and 216 . Each DIMM contains its own VPD module, such as VPDs 217 and 218 . In addition, memory card 213 also has unique VPD 219 . 6XX bridge 211 connects to PCI bridges 220 and 221 via system bus 222 . PCI bridges 220 and 221 are contained on native I/O (NIO) planar 223 which supports a variety of I/O components and interfaces. PCI bridge 221 provides connections for external data streams through network adapter 224 and a number of card slots 225 - 226 via PCI bus 227 . PCI bridge 220 connects a variety of I/O devices via PCI bus 228 . Hard disk 229 may be connected to SCSI host adapter 230 , which is connected to PCI bus 228 . Graphics adapter 231 may also be connected to PCI bus 228 as depicted, either directly or indirectly. ISA bridge 232 connects to PCI bridge 220 via PCI bus 228 . ISA bridge 232 provides interconnection capabilities through NIO controller 233 via ISA bus 234 , such as serial connections 235 and 236 . Floppy drive connection 237 provides removable storage. Keyboard connection 238 and mouse connection 239 allow data processing system 200 to accept input data from a user. Non-volatile RAM (NVRAM) 240 provides non-volatile memory for preserving certain types of data from system disruptions or system failures, such as power supply problems. System firmware 241 is also connected to ISA bus 234 and controls the initial BIOS using initial program load (IPL) code 242 containing hard-coded built-in self-test (BIST) signatures 243 . Service processor 244 is connected to ISA bus 234 and provides functionality for system diagnostics or system servicing. Service processor 244 detects errors and passes information to the operating system. The source of the errors may or may not be known to a reasonable certainty at the time that the error is detected. The operating system may merely log the errors against the system planar. For example, boot-time errors, severe intermittent problems, and adverse environmental computing conditions, such as conditional bandwidth bottlenecks, may be logged by the service processor into an error report buffer. These errors are eventually output and reported in some form, either to a hard drive or one of many types of backup systems. Each detected error may result in the generation of an error record comprising a timestamp at the time of detection, detailed data pertinent to the failing function, including physical location code, symptom bits, etc. Further analysis may be done at a later time if the error logs are stored in an error log file or error log buffer containing the data that some problem determination procedures may require for analysis. The manner of logging and processing a detected error may depend on the type of error and when the error occurs, e.g., whether the error occurs during system initialization procedures. If an error is detected during system initialization, all devices, components, or services within the data processing system may not have been initialized. For example, if an error is detected during system initialization, the service firmware may present certain errors to a system operator by writing error codes or error messages to an LCD display or system display monitor physically connected to the data processing system without being able to log error-derived data to the system log file. In other cases, the action of logging the data may start problem determination procedures in the operating system automatically. This may be accomplished by a deamon within the operating system that invokes pre-registered procedures based on the personality traits of the error logged. NIO planar 223 also contains unique VPD module 245 . Service processor 244 may read VPD modules 204 , 209 , 214 , 217 - 219 , and 245 via I 2 C bus 299 . The vital product data modules contain configuration information, such as product serial numbers, location of manufacturing, engineering change (EC) level data, FRU number, and part numbers that describe associated chips, boards, parts, etc. Other VPD information may include the speed, size, or other operational parameters of associated modules. Some of the VPD information in the VPD module may be written into the VPD module in a write-protected manner by a manufacturer just prior to completion and shipping of a product. Other VPD modules may be implemented within system 200 , such as a VPD module within network adapter 224 . Those of ordinary skill in the art will appreciate that the hardware in FIG. 2A may vary depending on the system implementation. For example, the system may have more processors, and other peripheral devices may be used in addition to or in place of the hardware depicted in FIG. 2 A. The depicted examples are not meant to imply architectural limitations with respect to the present invention. With reference now to FIG. 2B, a block diagram depicts an organization of internal components in a data processing system in accordance with a preferred embodiment of the present invention. Similar reference numerals refer to similar components in FIG. 2 A and FIG. 2 B. However, VPD modules 204 , 209 , 214 , 217 - 219 , and 245 in FIG. 2A have been replaced in FIG. 2B with VPD′ modules 290 - 296 , and IPL code 298 in FIG. 2A has been replaced with IPL code 299 in FIG. 2 B. Service processor 244 may still access VPD′ modules 290 - 296 via I 2 C bus 299 in which the VPD′ modules contain BIST signatures. By storing the chipset BIST signatures, such as POS BIST, LBIST, and ABIST signatures, in the VPD′ modules associated with the chipset, such as in VPD modules 290 - 296 , the IPL code can compare the chip BIST signatures that are generated during BISTs with the correct BIST signatures stored in the VPD modules rather than relying on a hard-coded BIST signature stored in the IPL code or system firmware. When the need arises to replace a planar with a newer chipset, the VPD′ modules 290 - 296 will be preconfigured with the new BIST signature for the new chipset. The present invention eliminates the need to modify the IPL code or perform a flash update for the new IPL code, which may corrupt the IPL code. With reference now to FIG. 3, a flowchart depicts a process by which IPL code verifies BIST signatures in accordance with a preferred embodiment of the present invention. The process begins with the power-on-reset initiating a BIST for a chip (step 302 ). The IPL code reads the BIST signature generated during the BIST, (step 304 ), and the IPL code also reads the predetermined, correct BIST signature stored in the VPD module associated with the chip (step 306 ). A determination is then made as to whether the generated BIST signature and the stored BIST signature are equal (step 308 ). If so, the IPL code continues with other boot functions. If not, then the BIST discrepancy is reported in an appropriate manner (step 310 ). The process is then complete with respect to initializing the chip. The advantages provided by the present invention should be apparent in view of the detailed description of the invention provided above. By storing BIST signatures in VPD modules, the need for potentially problematic updates of IPL code is eliminated, thereby saving repair cost and system downtime. It is important to note that while the present invention has been described in the context of a fully functioning data processing system, those of ordinary skill in the art will appreciate that the processes of the present invention are capable of being distributed in the form of a computer readable medium of instructions and a variety of forms and that the present invention applies equally regardless of the particular type of signal bearing media actually used to carry out the distribution. Examples of computer readable media include ROM chips or writable-type media such a floppy disc, a hard disk drive, a RAM, and CD-ROMs as well as transmission-type media such as digital and analog communications links. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention, the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

A method and apparatus for storing and using chipset built-in self-test (BIST) signatures is provided. A BIST for a chip in a data processing system may be initiated by a power-on-reset in the data processing system. The BIST signature generated during the BIST is compared with a predetermined BIST signature stored in a vital products data (VPD) module associated with the chip is read. A difference between the generated BIST signature and the predetermined BIST signature is then reported.

CROSS REFERENCE TO RELATED APPLICATIONS The present application claims priority under the International Convention of German Utility Model Application No. G 94 13 334.4, filed Aug. 18, 1994, the disclosure of which is incorporated herein by reference for all purposes. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to buffet platters, and more particularly to stackable buffet platters. 2. Description of the Prior Art Buffet platters for making up buffet meals are in common use in the catering trade, the known buffet planers consisting of a six or more sided plastic frame, which is assembled from six or more identical individual segments. These individual segments are screwed together, hidden on the inside. A mirror about four millimeters thick is clamped in the frame made up from the individual segments, a groove being cut in the inner side of the individual frame segments, in which groove the mirror is fitted and clamped by the screwing together of the individual segments. The upper and lower edges of these individual segments are so profiled that they prevent sideways slipping when stacking one on the other. These plastics frames have a frame height of about ten centimeters, so that the buffet platters can be stacked even with food served up on the mirror. However this construction has several disadvantages. Firstly, relative expensive manufacture results from the multi-part design with the individual segments, since the screw connections have to be made separately in the frame, which leads to substantial additional expense, especially with twelve or sixteen sided designs. Moreover round or oval basic shapes of the buffet platter can hardly be produced in this way. Secondly, a relatively small torsional strength results from the screwed construction, so that the clamped-in mirror can easily break with stronger one-sided loading. In addition, the mirror of the glass plate must be made as a food-carrying plate with a relatively large wall thickness, in order to be able to carry the served up food and provide sufficient stiffness even with twisting. However, this makes the buffet platter relatively heavy and thus awkward to handle. Furthermore, a particular disadvantage is that, because of the mirror clamped in the individual segments, juices or marinades can run into the clamping groove from the served up food, so that, for reasons of hygiene, the buffet platter has to be completely disassembled and thoroughly cleaned after practically every serving. SUMMARY OF THE INVENTION The present invention avoids the aforementioned disadvantages of the prior art with a buffet platter that is simple to make, is light in weight, and which is highly stable during use. Particularly simple manufacture results from the formation of the buffet platter in one piece, since its plastics frame can preferably be made as a deep drawn part in one working step. Thus, the manufacture of screw bores, threaded bushes and assembly of the individual segments are no longer necessary. In addition, this buffet platter has enhanced stability on account of the one-piece structure, so that the wall thickness can also be reduced and the overall weight of the buffet platter be reduced. A particular advantage is that the food-carrying plate is supported by a base surface formed in one piece with the plastics frame. This firstly results in additional stiffening of the plastics frame and secondly provides direct support for the food-carrying plate, so that this mirror or glass plate can also be made with a very small wail thickness. The wall strength or thickness of the food-carrying plate can even be reduced to a foil thickness, since the smooth surface is supported by the base surface. This results in further reduction of the total weight of the buffet planer, so that in all very good handiness is obtained. It is further of particular advantage that the food-carrying plate no longer has to be clamped in the plastics frame, because of the continuous support on the base surface, but can be placed directly on the frame, whereby the grooves at the edge of the buffet platter which demand so much cleaning are avoided. It is further advantageous that, on account of the small wall thickness of the plastics frame, provision of a parking edge by the raised profiling of the plastics frame cooperating with the lower edge of the buffet platter stacked thereon, gives security against sideways slipping, without the underside having to have additional profiling worked thereon. This results in reliable centring of the buffet platters stacked on top of each other, so that relatively high stacks can be made up for serving or catering purposes. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the buffet platter will now be described in more detail and explained with reference to the drawings, in which: FIG. 1 is a plan view of a buffet platter with a six-sided basic shape; FIG. 2 is a side view of the buffet platter according to FIG. 1 in half section, with a schematic representation of stacking; FIG. 3 shows an enlarged edge region of the buffet platter according to FIG. 2. DESCRIPTION OF THE PREFERRED EMBODIMENTS A buffet platter 1 is shown in FIG. 1, with a six-sided basic shape, the buffet platter 1 being formed essentially by a likewise six-sided plastics frame 2 and a food-carrying plate 3 placed thereon for serving foodstuffs. There is a raised profiling 4 surrounding the outer edge of the plastics frame 2, so that when placing several buffet platters 1 one on top of the other (cf. FIG. 2), the profiling 4 is engaged by the respective bottom edge la of the buffet platter 1, wherein a narrow parking edge 4a of the plastics frame 2 is provided adjacent the surrounding profiling 4 as a transition to the outer periphery of the plastics frame 2, on which edge 4a the bottom edge 1a bears. In accordance with the novelty, the plastics frame 2 of the buffet platter 1 is provided with a base surface 5, on which the food-carrying plate 3, preferably a mirrored glass plate, lies and is thus supported. The plastics frame 2 is preferably formed from a plastics plate as a deep drawn part, so that the shape shown in half section in FIG. 2 results. It is important that arbitrary shapes, for example semicircular or oval shapes can be formed in a simple way by suitable design of the deep drawing tool, because of the formation of the plastics frame 2 in one piece. The food-carrying plate 3 is at least for the most part supported by the base surface 5, this base surface 5 being reined continuously in general. However openings 6, recesses and/or hollows can be formed or pressed in the base surface 5 in the deep drawing operation, so that there is a further reduction in weight and an increase in the stiffness of form of the plastics frame 2. It should be noted that, in contrast to the known buffet platter with a plastics frame consisting of a plurality of individual segments, each side is connected through the base surface 5 to the opposed side of the plastics frame 2 by virtue of the one-piece design of the plastics frame 2, so that a construction which is particularly torsionally stiff results. Handles 9 or gripping recesses can be formed directly on the plastics frame 2, so that the buffet platter 1 can be carried easily. The buffet platter 1 according to FIG. 1 is shown in half section in FIG. 2, from which the direct bearing and wide-area support of the food-carrying plate 3 by the base surface 5 is in particular apparent. It should be mentioned that, on account of this support by means of the base surface 5, the food-carrying plate 3 can be made relatively thin and can even only have a wall thickness like that of a foil. The food-carrying plate 3 can also be in the form of a transparent glass plate, so that the base surface 5 can also serve as a display plate by virtue of its recessed form, for example through a hollow 6' shown in broken lines, in which hollow 6' decorations, for example flowers, can be placed. The hollow 6' can also be accessible by a drawer or a screw cover. Partial silvering of the food-carrying plate 3 is also possible, in which the annular region of the food-carrying plate 3 which lies on the base surface 5 is silvered, while the central region over the, hollow 6' or the opening 6 is transparent, in order to leave the view clear to the decoration or a business logo. In order to increase the sideways security against slipping with a plurality of buffet platters 1, 1', 1", etc. stacked on each other as shown in FIG. 2, plurality of clips 10 can be provided on the inner periphery of the plastics frame 2, having an offset part engaging the profiling 4 of the buffet platter 1' stacked thereunder from the inside. Thus, in addition to the engagement of the lower edge 1a with the profiling 4 from the outside, there is a further engagement from the inside, as is shown especially in FIG. 3 in an enlargement of the corner region B. It should be mentioned that these clips could be stuck on to the inner periphery of the plastics frame 2 but also in implementation with only two clips 10, they can be screwed on at the same time as the handles 9, as is shown in FIG. 3. As can be seen from FIG. 2, when the buffet platter 1 is placed on the buffet platter 1' stacked thereunder, the lower edge 1a engages the profiling 4 from the outside and the clips 10 engage the profiling 4 from the inside, so that a particularly stable stack results from stacking a plurality of buffet platters in accordance with the arrow A. As is further apparent, by stacking a plurality of buffet platters 1, 1', 1", etc. on one another, a hollow space is created in each case, so that prepared meals can be kept dust-tight and be transported. The region B indicated by a circle in FIG. 2 is shown enlarged and in cross section in FIG. 3. From this can be seen in particular the relatively thin-walled design of the plastics frame 2, the raised form of the profiling 4 and the support of the food-carrying plate 3 by the base surface 5, In order to increase the stiffness of the shape, raised parts 7 in the form of webs, ribs or pips can also be provided on the base surface 5, which also results in the food-carrying plate 3 resting at points. In order to reduce the weight, stamped out pans or openings 6 can be provided in the base surface 5, without the load-beating capacity of the base surface 5 being substantially reduced. The food-carrying plate 3 is stuck on to the base surface 5 in order to fix it inside the plastics frame 2, preferably by spot application of adhesive, as is known in fixng tiles for example. The gap resulting at the edge region of the food-carrying plate 3 relative to the plastics frame 2 and its profiling 4 is filled with a jointing material 8 impervious to foodstuffs, in order to avoid leakage of food juices, sauces and the like here, as well as to facilitate cleaning. Irregularities in the cutting of the food-carrying plate by the glassworks can also be compensated for by this jointing material 8, preferably a silicone, so that, in contrast to the known buffet platter the food-carrying plate 3 does not have to be cut particularly accurately out of mirror glass. In the side region of FIG. 3 there is moreover shown the fixing of the handle 9, in which its yoke is merely stuck through the plastics frame 2 and screwed up by a cap nut. The offset clips 10 can be fixed at the same time by means of aligned bores. The underside of the clips 10 then fits from the inside round the profiling 4 of the next buffet platter thereunder in the superimposed state. In general two or three such clips 10 suffice for this additional security against slipping by internal engagement, as is shown for example in FIG. 1 in hidden, broken lines. Although a six-sided buffet platter 1 is here shown in FIGS. 1 and 2, the plastics frame 2 and correspondingly the food-carrying plate 3 can have any arbitrary basic shape, especially a circular or oval shape, as is often desired for buffet serving of dishes. Six, eight or twelve-sided shapes can also be made simply. After making the one-piece plastics frame 2 by forming of a unitary plastics sheet, preferably by deep drawing a unitary or one-piece plastics plate, the food-carrying plate 3 is cut according to the basic shape of the plastics frame 2 and laid on the base surface 5 and stuck on. It is important that the food-carrying plate 3 is held without stress within the plastics frame 2 and is no longer clamped in, in contrast to the state of the art. This reduces the danger of breakage substantially, since there are not stresses in the food-carrying plate 3. Because of this the novel buffet platter 1 can even drop from small heights without breaking. Furthermore the food-carrying plate 3 can also consist of very thin glass or even of mirrored metal foil or an electro-deposited metal layer, since the support function is taken over by the base surface 5. This results in a substantial saving in weight and thus easier handling in transport and in making up the buffet. While this invention has been described in terms of several preferred embodiments, it is contemplated that alterations, permutations, and equivalents thereof will become apparent to those skilled in the art after studying preceding descriptions and the drawing. It is therefore intended that the following appended claims be interpreted to include all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.

A buffet platter with a plastic frame for maintaining the space between buffet platters stacked on each other has a smooth-surfaced, preferably mirrored, food-carrying plate at the upper side is surrounded by the plastic frame, which is profiled at the outer edge to engage with a buffet platter of the same design stacked thereon, in order to prevent sideways slipping. The plastic frame is formed in one piece and the food-carrying plate is supported on a base surface of the plastic frame that is formed in one piece with the plastics frame.

CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation of U.S. patent application Ser. No. 12/185,425, filed Aug. 4, 2008, now U.S. Pat. No. 8,148,699, issued Apr. 3, 2012, which is a continuation of U.S. patent application Ser. No. 11/078,706, filed Mar. 14, 2005, now U.S. Pat. No. 7,408,174, issued Aug. 5, 2008, which claims the benefit under 35 U.S.C. §119(e) of provisional patent application Ser. No. 60/552,185 filed on Mar. 12, 2004 and Ser. No. 60/613,215 filed on Sep. 28, 2004, the contents of each of which are hereby incorporated by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention In one of its aspects, the present invention relates to a fluid treatment system, more particularly, an ultraviolet radiation water treatment system. In another of its aspects, the present invention relates to a method for treating a fluid, more particularly a method for irradiating water. 2. Description of the Prior Art Fluid treatment systems are generally known in the art. More particularly, ultraviolet (UV) radiation fluid treatment systems are generally known in the art. Early treatment systems comprised a fully enclosed chamber design containing one or more radiation (preferably UV) lamps. Certain problems existed with these earlier designs. These problems were manifested particularly when applied to large open flow treatment systems which are typical of larger scale municipal waste water or potable water treatment plants. Thus, these types of reactors had associated with them the following problems: relatively high capital cost of reactor; difficult accessibility to submerged reactor and/or wetted equipment (lamps, sleeve cleaners, etc); difficulties associated with removal of fouling materials from fluid treatment equipment; relatively low fluid disinfection efficiency, and/or full redundancy of equipment was required for maintenance of wetted components (sleeves, lamps and the like). The shortcomings in conventional closed reactors led to the development of the so-called “open channel” reactors. For example, U.S. Pat. Nos. 4,482,809, 4,872,980 and 5,006,244 (all in the name of Maarschalkerweerd and all assigned to the assignee of the present invention and hereinafter referred to as the Maarschalkerweerd #1 Patents) all describe gravity fed fluid treatment systems which employ ultraviolet (UV) radiation. Such systems include an array of UV lamp modules (e.g., frames) which include several UV lamps each of which are mounted within sleeves which extend between and are supported by a pair of legs which are attached to a cross-piece. The so-supported sleeves (containing the UV lamps) are immersed into a fluid to be treated which is then irradiated as required. The amount of radiation to which the fluid is exposed is determined by the proximity of the fluid to the lamps, the output wattage of the lamps and the flow rate of the fluid past the lamps. Typically, one or more UV sensors may be employed to monitor the UV output of the lamps and the fluid level is typically controlled, to some extent, downstream of the treatment device by means of level gates or the like. The Maarschalkerweerd #1 Patents teach fluid treatment systems which were characterized by improved ability to extract the equipment from a wetted or submerged state without the need for full equipment redundancy. These designs compartmentalized the lamp arrays into rows and/or columns and were characterized by having the top of the reactor open to provide free-surface flow of fluid in a “top open” channel. The fluid treatment system taught in the Maarschalkerweerd #1 Patents is characterized by having a free-surface flow of fluid (typically the top fluid surface was not purposely controlled or constrained). Thus, the systems would typically follow the behavior of open channel hydraulics. Since the design of the system inherently comprised a free-surface flow of fluid, there were constraints on the maximum flow each lamp or lamp array could handle before either one or other hydraulically adjoined arrays would be adversely affected by changes in water elevation. At higher flows or significant changes in the flow, the unrestrained or free-surface flow of fluid would be allowed to change the treatment volume and cross-sectional shape of the fluid flow, thereby rendering the reactor relatively ineffective. Provided that the power to each lamp in the array was relatively low, the subsequent fluid flow per lamp would be relatively low. The concept of a fully open channel fluid treatment system would suffice in these lower lamp power and subsequently lower hydraulically loaded treatment systems. The problem here was that, with less powerful lamps, a relatively large number of lamps was required to treat the same volume of fluid flow. Thus, the inherent cost of the system would be unduly large and/or not competitive with the additional features of automatic lamp sleeve cleaning and large fluid volume treatment systems. This led to the so-called “semi-enclosed” fluid treatment systems. U.S. Pat. Nos. 5,418,370, 5,539,210 and Re36,896 (all in the name of Maarschalkerweerd and all assigned to the assignee of the present invention and hereinafter referred to as the Maarschalkerweerd #2 patents) all describe an improved radiation source module for use in gravity fed fluid treatment systems which employ UV radiation. Generally, the improved radiation source module comprises a radiation source assembly (typically comprising a radiation source and a protective (e.g., quartz) sleeve) sealingly cantilevered from a support member. The support member may further comprise appropriate means to secure the radiation source module in the gravity fed fluid treatment system. Thus, in order to address the problem of having a large number of lamps and the incremental high cost of cleaning associated with each lamp, higher output lamps were applied for UV fluid treatment. The result was that the number of lamps and subsequent length of each lamp was dramatically reduced. This led to commercial affordability of automatic lamp sleeve cleaning equipment, reduced space requirements for the treatment system and other benefits. In order to use the more powerful lamps (e.g. medium pressure UV lamps), the hydraulic loading per lamp during use of the system would be increased to an extent that the treatment volume/cross-sectional area of the fluid in the reactor would significantly change if the reactor surface was not confined on all surfaces, and hence such a system would be rendered relatively ineffective. Thus, the Maarschalkerweerd #2 patents are characterized by having a closed surface confining the fluid being treated in the treatment area of the reactor. This closed treatment system had open ends which, in effect, were disposed in an open channel. The submerged or wetted equipment (UV lamps, cleaners and the like) could be extracted using pivoted hinges, sliders and various other devices allowing removal of equipment from the semi-enclosed reactor to the free surfaces. The fluid treatment system described in the Maarschalkerweerd #2 patents was typically characterized by relatively short length lamps which were cantilevered to a substantially vertical support arm (i.e., the lamps were supported at one end only). This allowed for pivoting or other extraction of the lamp from the semi-enclosed reactor. These significantly shorter and more powerful lamps inherently are characterized by being less efficient in converting electrical energy to UV energy. The cost associated with the equipment necessary to physically access and support these lamps was significant. Historically, the fluid treatment modules and systems described in the Maarschalkerweerd #1 and #2 patents have found widespread application in the field of municipal waste water treatment (i.e., treatment of water that is discharged to a river, pond, lake or other such receiving stream). In the field of municipal drinking water, it is known to utilize so-called “closed” fluid treatment systems or “pressurized” fluid treatment systems. Closed fluid treatment devices are known—see, for example, U.S. Pat. No. 5,504,335 (Maarschalkerweerd #3). Maarschalkerweerd #3 teaches a closed fluid treatment device comprising a housing for receiving a flow of fluid. The housing comprises a fluid inlet, a fluid outlet, a fluid treatment zone disposed between the fluid inlet and the fluid outlet, and at least one radiation source module disposed in the fluid treatment zone. The fluid inlet, the fluid outlet and the fluid treatment zone are in a collinear relationship with respect to one another. The at least one radiation source module comprises a radiation source sealably connected to a leg which is sealably mounted to the housing. The radiation source is disposed substantially parallel to the flow of fluid. The radiation source module is removable through an aperture provided in the housing intermediate to fluid inlet and the fluid outlet thereby obviating the need to physically remove the device for service of the radiation source. U.S. Pat. No. 6,500,346 [Taghipour et al. (Taghipour)] also teaches a closed fluid treatment device, particularly useful for ultraviolet radiation treatment of fluids such as water. The device comprises a housing for receiving a flow of fluid. The housing has a fluid inlet, a fluid outlet, a fluid treatment zone disposed between the fluid inlet and the fluid outlet and at least one radiation source having a longitudinal axis disposed in the fluid treatment zone substantially transverse to a direction of the flow of fluid through the housing. The fluid inlet, the fluid outlet and the fluid treatment zone are arranged substantially collinearly with respect to one another. The fluid inlet has a first opening having: (i) a cross-sectional area less than a cross-sectional area of the fluid treatment zone, and (ii) a largest diameter substantially parallel to the longitudinal axis of the at least one radiation source assembly. Practical implementation of known fluid treatment systems of the type described above have been such that the longitudinal axis of the radiation source is: (i) parallel to the direction of fluid flow through the fluid treatment system, or (ii) orthogonal to the direction of fluid flow through the fluid treatment system. Further, in arrangement (ii), it has been common to place the lamps in an array such that, from an upstream end to a downstream end of the fluid treatment system, a downstream radiation source is placed directly behind an upstream radiation source. The use of arrangement (ii) in an UV radiation water treatment system has been based on the theory that radiation was effective up to a prescribed distance from the radiation source, depending on the transmittance of the water being treated. Thus, it has become commonplace to interspace the radiation sources in arrangement (ii) such that the longitudinal axes of adjacent radiation sources are spaced at a distance equal to approximately twice the prescribed distance mentioned in the previous sentence. Unfortunately, for the treatment of large volumes of fluid, arrangement (ii) can be disadvantageous for a number of reasons. Specifically, implementation of arrangement (ii) requires a relatively large “footprint” or space to house the radiation sources. Further, the use of a large number of radiation sources in arrangement (ii) creates a relatively large coefficient of drag resulting in a relatively large hydraulic pressure loss/gradient over the length of the fluid treatment system. Still further, the use of a large number of radiation sources in arrangement (ii) can produce vortex effects (these effects are discussed in more detail hereinbelow) resulting in forced oscillation of the radiation sources—such forced oscillation increases the likelihood of breakage of the radiation source and/or protective sleeve (if present). Accordingly, there remains a need in the art for a fluid treatment system, particularly a closed fluid treatment system which has one or more of the following features: it can treat large volumes of fluid (e.g., wastewater or drinking water and the like); it can increase the limit of the maximum admissible velocity through the reactor; it requires a relatively small “footprint”; it results in a relatively lower coefficient of drag resulting in an improved hydraulic pressure loss/gradient over the length of the fluid treatment system; it results in relatively lower (or no) forced oscillation of the radiation sources thereby obviating or mitigating breakage of the radiation source and/or protective sleeve (if present); it can be readily adapted to make use of relatively recently developed so-called “low pressure high output” (LPHO), amalgam and/or other UV emitting lamps while allowing for ready extraction of the lamps from the fluid treatment system for servicing and the like; it can employ a lamp of a standard length for varying widths of reactors; it can be readily combined with a cleaning system for removing fouling materials from the exterior of the radiation source(s); it can be readily installed in a retrofit manner in an existing fluid treatment plant; and it provides relatively improved disinfection performance compared to conventional fluid treatment systems. SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel fluid treatment system which obviates or mitigates at least one of the above-mentioned disadvantages of the prior art. In one of its aspects, the present invention relates to a fluid treatment system comprising: an inlet; an outlet; a fluid treatment zone disposed between the inlet and the outlet, the fluid treatment zone having disposed therein: (i) an elongate first radiation source assembly having a first longitudinal axis, and (ii) an elongate second radiation source assembly having a second longitudinal axis; wherein the first longitudinal axis and the second longitudinal axis are non-parallel to each other and to a direction of fluid flow through the fluid treatment zone. In another of its aspects, the present invention relates to a fluid treatment system comprising: an inlet; an outlet; a fluid treatment zone disposed between the inlet and the outlet, the fluid treatment zone having disposed therein an array of radiation source assemblies arranged serially from an upstream region to a downstream region of fluid treatment zone such that: (i) each radiation source assembly has a longitudinal axis transverse to a direction of fluid flow through the fluid treatment zone, (ii) the longitudinal axis of an upstream radiation source assembly is staggered with respect to a downstream radiation source assembly in a direction orthogonal to the direction of fluid flow through the fluid treatment zone to define a partial overlap between the upstream radiation source assembly and the downstream radiation source assembly, and (iii) a flow of fluid has no unobstructed path through the fluid treatment zone. In another of its aspects, the present invention relates to a fluid treatment system comprising: an inlet; an outlet; a fluid treatment zone disposed between the inlet and the outlet, the fluid treatment zone having disposed therein an array of rows of radiation source assemblies; each radiation source assembly having a longitudinal axis transverse or parallel to a direction of fluid flow through the fluid treatment zone; each row comprising a plurality of radiation source assemblies in spaced relation in a direction transverse to the direction of fluid flow through the fluid treatment zone to define a gap through which fluid may flow between an adjacent pair of radiation source assemblies; all rows in the array being staggered with respect to one another in a direction orthogonal to the direction of fluid flow through the fluid treatment zone such that the gap between an adjacent pair of radiation source assemblies in an upstream row of radiation source assemblies is partially or completely obstructed in the direction of fluid flow by at least two serially disposed downstream rows of radiation source assemblies. In yet another of its aspects, the present invention relates to a fluid treatment system comprising: an inlet; an outlet; a fluid treatment zone disposed between the inlet and the outlet, the fluid treatment zone having disposed therein an array of radiation source assemblies, each radiation source assembly having a longitudinal axis transverse to a direction of fluid flow through the fluid treatment zone; the array of radiation source assemblies comprising: a first row of radiation source assemblies, a second row of radiation source assemblies downstream from the first row of radiation source assemblies, a third row of radiation source assemblies downstream from the second row of radiation source assemblies and a fourth row of radiation source assemblies downstream from the third row of radiation source assemblies; an adjacent pair of radiation source assemblies in the first row defining a first gap through which fluid may flow, a radiation source assembly from the second row partially obstructing the first gap to divide the first gap into a second gap and a third gap, a radiation source assembly from the third row at least partially obstructing the second gap and a radiation source assembly from the fourth row at least partially obstructing the third gap. In yet another of its aspects, the present invention relates to a fluid treatment system comprising: an inlet; an outlet; a fluid treatment zone disposed between the inlet and the outlet, the fluid treatment zone having disposed therein an array comprising 4 rows radiation source assemblies arranged serially from an upstream portion to a downstream portion of the fluid treatment zone; each radiation source assembly having a longitudinal axis transverse to a direction of fluid flow through the fluid treatment zone; wherein: (i) a first pair of rows of radiation source assemblies in the array comprise substantially uniform spacing between adjacent pairs of radiation source assemblies in the row; and (ii) a second pair of rows of radiation source assemblies in the array comprise substantially non-uniform spacing between adjacent pairs of radiation source assemblies in the row. In addition to the arrayed arrangement of radiation source assemblies described above, it is possible to utilize so-called boundary radiation source assemblies—i.e., radiation source assemblies placed in parallel and in close proximity to the opposed reactor walls. All axes of the boundary radiation source assemblies adjacent to one another, either of the respective outer boundary radiation source assemblies are in the same plane. Thus, the present inventors have discovered a fluid treatment system having one or more of the following advantages: it can treat large volumes of fluid (e.g., wastewater, drinking water or the like); it can increase the limit of the maximum admissible velocity through the reactor; it requires a relatively small “footprint”; it results in a relatively lower coefficient of drag resulting in an improved hydraulic pressure loss/gradient over the length of the fluid treatment system; it results in relatively lower (or no) forced oscillation of the radiation sources thereby obviating or mitigating of breakage of the radiation source and/or protective sleeve (if present); it can be readily adapted to make use of low pressure ultraviolet emitting lamps and relatively recently developed so-called “low pressure high output” (LPHO), amalgam and/or other ultraviolet radiation and photon emitting lamps while allowing for ready extraction of the lamps from the fluid treatment system for servicing and the like; it can employ a lamp of standard length for varying widths of reactors simply by varying the transverse angle between the lamps; it can be readily combined with a cleaning system for removing fouling materials from the exterior of the radiation source(s); it can be readily installed in a retrofit manner in an existing fluid treatment plant; and it provides relatively improved disinfection performance compared to conventional fluid treatment systems (e.g., systems in which the radiation source is disposed such that its longitudinal axis is parallel or orthogonal to the direction of fluid flow through the fluid treatment zone contained within the system). In one of its general aspects, the present invention relates to a fluid treatment system comprising at least two radiation source assemblies arranged in a novel manner. Specifically, the radiation source assemblies are arranged such that the respective longitudinal axes of the radiation sources therein are in a non-parallel relationship with each other and with respect to the direction of fluid flow through the fluid treatment zone. This is different than conventional fluid treatment systems wherein all lamps are arranged such that the longitudinal axes of the respective radiation sources within the radiation source assemblies are in a parallel relationship and these axes are orthogonal or parallel to the direction of fluid flow. In a particularly preferred embodiment of this aspect of the invention, the radiation source assemblies are arranged in an array which is generally V-shaped. In this embodiment, it is preferred to have respective banks of radiation source assemblies which are stacked to form the V-shaped arrangement. As will be discussed in more detail below, one of the advantages of orienting the radiation source assemblies in this matter is a significant reduction in forced oscillation of the radiation sources due to vortex effects. In another of its aspects, the present invention relates to a fluid treatment system wherein the radiation source assemblies are arranged transverse or parallel to the direction of fluid flow through the fluid treatment zone as a series of rows, each row comprising a plurality of radiation sources assemblies spaced apart in a direction orthogonal to the direction of fluid flow through the fluid treatment zone. In one embodiment of this aspect of the invention (also referred to as the “staggered/transverse orientation”), the radiation source assemblies are arranged transverse to the direction of fluid flow through the fluid treatment zone and oriented in a manner whereby, from an upstream portion to a downstream portion of the fluid treatment zone, the radiation source assemblies are staggered in a direction orthogonal to a direction of fluid flow through the fluid treatment zone to define partial overlap between these assemblies. Preferably, the collection of assemblies is arranged such that a flow of fluid has no unobstructed path through the arrangement of radiation source assemblies in the fluid treatment zone. Practically, one may envision this by viewing the inlet of the fluid treatment zone and seeing no clear, unobstructed path through the arrangement of radiation source assemblies in the fluid treatment zone from the inlet to the outlet. In another embodiment of this aspect of the invention (also referred to as the “staggered/parallel orientation”), the radiation source assemblies are arranged parallel to the direction of fluid flow through the arrangement of radiation source assemblies in the fluid treatment zone and oriented in a manner whereby, from an upstream portion to a downstream portion of the fluid treatment zone, the radiation source assemblies are arranged as in the form of at least two serially disposed banks such that rows of radiation source assemblies in an upstream bank are staggered with respect to rows of radiation source assemblies in a downstream bank in a direction orthogonal to the direction of fluid flow through the arrangement of radiation source assemblies in the fluid treatment zone. In another of its aspects, the present invention relates to a fluid treatment system in which an array of radiation source assemblies are arranged in the fluid treatment zone. The radiation source assemblies are oriented transverse to the direction of fluid flow through the fluid treatment zone. The array of radiation source assemblies includes a first row of radiation source assemblies arranged to define a predetermined spacing between pairs of radiation source assemblies in the row in a direction orthogonal to the direction of fluid flow through the fluid treatment zone. At least two further rows of radiation source assemblies are disposed downstream of the first row of radiation source assemblies. In one preferred embodiment, these downstream rows of radiation source assemblies (i.e., two or more of such rows) combine to fill or occupy the pre-determined spacing between pairs of radiation source assemblies within the column of lamps in the first row—i.e., if one were to view the array of radiation source assemblies from the inlet of the fluid treatment system. In another preferred embodiment, these downstream rows of radiation source assemblies (i.e., two or more of such rows) combine only to partially fill or occupy the pre-determined spacing between pairs of radiation source assemblies within the column of lamps in the first row—i.e., if one were to view the array of radiation source assemblies from the inlet of the fluid treatment system. In the present fluid treatment system, it is possible to incorporate a so-called transition region upstream and/or downstream of the fluid treatment zone. Preferably, such a transition region serves to funnel or otherwise transition the flow of fluid in a manner such that cross-sectional area of the flow of fluid orthogonal to the direction of fluid flow is: (i) increased (if the transition region is placed upstream of the fluid treatment zone) thereby decreasing fluid flow velocity, or (ii) decreased (if the transition region is placed downstream of the fluid treatment zone) thereby increasing fluid flow velocity. Throughout the specification, reference is made to terms such as “closed zone”, “closed cross-section” and “constrained”. In essence, these terms are used interchangeably and are intended to encompass a structure which effectively surrounds the fluid flow in a manner similar to that described in the Maarschalkerweerd #2 patents (with particular reference to the fluid treatment zone described therein). Further, as used throughout this specification, the term “fluid” is intended to have a broad meaning and encompasses liquids and gases. The preferred fluid for treatment with the present system is a liquid, preferably water (e.g., wastewater, industrial effluent, reuse water, potable water, ground water and the like). Still further, the terms “rows” and “columns” are used throughout this specification in relation to arrangements of radiation sources and it is to be understood that these terms are used interchangeably. Those with skill in the art will recognize that there is reference throughout the specification to the use of seals and the like to provide a practical fluid seal between adjacent elements in the fluid treatment system. For example, those of skill in the art will recognize that it is well known in the art to use combinations of coupling nuts, O-rings, bushings and like to provide a substantially fluid tight seal between the exterior of a radiation source assembly (e.g., water) and the interior of a radiation source assembly containing the radiation source (e.g., an ultraviolet radiation lamp). BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will be described with reference to the accompanying drawings, wherein like numerals designate like elements, and in which: FIG. 1 illustrates, in perspective view, partially cutaway, a schematic of a first embodiment of the present fluid treatment system; FIG. 2 illustrates a perspective view, partially cutaway of a second embodiment of the present fluid treatment system; FIG. 3 illustrates an end view from the inlet of the fluid treatment system illustrated in FIG. 2 ; FIG. 4 illustrates a top view (partially cutaway) of the fluid treatment system illustrated in FIG. 2 ; FIG. 5 illustrates a side elevation of the fluid treatment system illustrated in FIG. 2 ; FIG. 6 illustrates a schematic side elevation of orientation of radiation source assemblies in a third embodiment of the present fluid treatment system; FIG. 7 illustrates a schematic side elevation of orientation of radiation source assemblies in a fourth embodiment of the present fluid treatment system; FIG. 8 a illustrates a top view (partially cutaway) of a fifth embodiment of the present fluid treatment system; FIG. 8 b illustrates a top view (partially cutaway) of a sixth embodiment of the present fluid treatment system; FIG. 9 illustrates a top view of an array of radiation source assemblies incorporating a cleaning device for removing fouling materials from the exterior of the assemblies; FIG. 10 illustrates vortices generated as fluid flows passes a radiation source assembly of a prior art fluid treatment system; FIG. 11 illustrates vortices generated as fluid flows passes a radiation source assembly of a fluid treatment system in accordance with the present invention; FIGS. 12-15 , there is illustrated schematic end views (i.e., viewed through the fluid treatment zone) of a number of embodiments of the staggered/parallel orientation referred to above; and FIG. 16 illustrates a schematic side elevation of orientation of radiation source assemblies in a highly preferred embodiment of the present fluid treatment system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1 , there is illustrated a fluid treatment system 10 . Fluid treatment system 10 comprises an inlet 12 and an outlet 24 . Disposed between inlet 12 and outlet 24 is a fluid treatment zone 20 . Fluid treatment zone 20 is interconnected to inlet 12 by an inlet transition zone 14 comprising a first transition region 16 and intermediate transition region 18 . Outlet 24 is interconnected to fluid treatment zone 20 by an outlet transition zone 22 . As illustrated, fluid passes through fluid treatment system 10 (including fluid treatment zone 20 ) in the direction of arrow A. As shown, each of inlet 12 , inlet transition zone 14 , fluid treatment zone 20 , outlet transition zone 22 and outlet 24 have a closed cross-section. The use of the term “closed cross-section” is intended to mean an enclosure which bounds a flow of fluid on all sides and/or surfaces. As shown, inlet 12 and outlet 24 have a circular cross-section much like a conventional pipe arrangement. As further illustrated, fluid treatment zone 20 has a square or rectangular cross-section. Of course it is possible to configure fluid treatment zone 20 to have other cross-sectional shapes. Disposed in fluid treatment zone 20 is a first bank 26 of radiation source assemblies and a second bank 28 of radiation source assemblies. Each radiation source assembly in banks 26 and 28 is elongate and has a longitudinal axis which is angled with respect to the direction of fluid flow (see arrow A or dashed lined 30 which is a projection of arrow A) through fluid treatment zone 20 . The radiation source assemblies in bank 26 are mounted on one side of fluid treatment zone 20 and have a distal end thereof supported by a support element 32 . Similarly, each radiation source assembly in bank 28 has one end mounted on a side of fluid treatment zone 20 and a distal end thereof supported by support element 32 . In the result, the array of radiation source assemblies presented by banks 26 and 28 to the flow of fluid is in the form of an V-shaped configuration with the apex of the “V” being pointed toward the flow of fluid. Of course, the apex of the “V” could be pointed in the opposite direction. Further, while the distal end of each radiation source assembly in banks 26 and 28 is supported by a single support element 32 , other support elements will be apparent of those of skill in the art. As shown, intermediate transition region 18 serves the purpose of providing a nesting region for the apex of the array of lamps. As such, it is preferred to have the sides of intermediate transition region 18 tapered to a smaller dimension while, in the illustrated embodiment, maintaining the top and bottom at a consistent dimension (this will be discussed further below). First transition region 16 interconnects intermediate transition region 18 and inlet 12 , and serves the purpose of: (i) reducing the dimension of the enclosure, and (ii) transitioning the cross-section shape from a polygon to a circle. Similarly, outlet transition zone 22 serves to reduce the dimension of the enclosure and transition the cross-sectional shape of the enclosure from a circle to a polygon. The use of inlet transition zone 14 and outlet transition zone 22 also serves to obviate or mitigate hydraulic head loss problems that might occur if dramatic changes in dimensions of the enclosure were cast into the system. A second embodiment of the present fluid treatment system will now be discussed with reference to FIGS. 2-5 . In FIGS. 2-5 , elements having the same last two digits as elements appearing in FIG. 1 are attended to denote like elements. With reference to FIGS. 2-5 , there is illustrated a fluid treatment system 100 . Fluid treatment system 100 comprises an inlet 112 and an outlet 124 . Fluid treatment system 100 further comprises a fluid treatment zone 120 . Inlet 112 is interconnected to fluid treatment zone 120 by an inlet transition zone 114 . Fluid outlet 124 is interconnected to fluid treatment zone 120 by an outlet transition zone 122 . Inlet transition zone 114 comprises a first transition region 116 and an intermediate transition region 118 . Disposed in fluid treatment zone 120 is a first bank 126 of radiation source assemblies and a second bank 128 of radiation source assemblies. The orientation of the radiation source assemblies in banks 126 and 128 with respect to the direction of fluid flow through fluid treatment zone 120 is similar as that described above with respect to FIG. 1 . As shown, the distal portion of each radiation source assembly in banks 126 and 128 is supported by a support post which is disposed transverse to: (i) the direction of fluid flow through fluid treatment zone 120 , and (ii) the longitudinal axis of each radiation source assembly. As shown, particularly with respect to FIG. 4 , a support post 134 is used for each column of radiation source assemblies in banks 126 and 128 . As further illustrated FIG. 4 , the upstream end of the array of radiation sources comprises a column of radiation source assemblies from bank 126 connected to a support post 134 —i.e., there is no similar column of radiation source assemblies from bank 128 supported by the upstream centre support. This arrangement is reversed at a downstream support post 134 a . Otherwise, each centre post serves the purpose of supporting a distal portion of radiation source assemblies from one column of each of banks 126 and 128 . In some cases support post 134 also acts as a baffle, and likely will act as a protective shield behind which will be parked a cleaning device (described below). With particular reference to FIGS. 2 and 5 , it can be seen that mounting sleeves 136 are cast or otherwise secured to the exterior surface of fluid treatment zone 120 . The proximal region of each radiation source assembly is received in mounting sleeves 136 and a fluid type seal (not shown) can be achieved in a conventional manner. As further illustrated in FIGS. 2-5 , inlet 112 and outlet 124 can be adapted to have a suitable standard flange element 113 and 125 , respectively. This facilitates insulation of fluid treatment system 100 in conventional piping. For example, it is possible for flange elements 113 and 125 to be configured for conventional piping sizes between, for example, 12 inches and 72 inches. With particular reference to FIG. 3 , it will be seen that banks 126 and 128 are arranged as an array of radiation source assemblies that present an obstruction which completely fills fluid treatment zone 120 when the fluid treatment zone 120 is viewed through inlet 112 . In other words, there is no apparent path by which fluid can pass through fluid treatment zone 120 without being forced to detour around a radiation source assembly in banks 126 and/or 128 . This being the case, the axis of each radiation source assembly can be seen by an observer looking along the direction of fluid flow through fluid treatment zone 120 . This effect is created by partially staggering the orientation of radiation source assemblies in banks 126 and 128 . For example, with reference to FIG. 5 , it can be seen that, proceeding lengthwise along fluid treatment zone 120 , there is partial overlap of an upstream radiation source assembly with a downstream radiation source assembly in a successive manner—see, for example, lines 150 in FIG. 5 which illustrate such a gradual staggering of radiation source assemblies in each of banks 126 and 128 . In other words, a downstream radiation source assembly is partially exposed and partially obscured by an adjacent upstream radiation source assembly. Thus, it can be seen that the complete obstruction of the cross-sectional area the section of fluid treatment zone 120 (i.e., the section in which banks 126 and 128 are disposed) discussed above is not achieved by staggering of two successive columns of radiation source assemblies in banks 126 and 128 such that a downstream radiation source assembly fills the space between a pair of upstream radiation source assemblies. Rather, in this embodiment, three or more columns of such radiation source assemblies are oriented, in combination, to achieve the complete obstruction. Preferably, each radiation source assembly preferably comprises of an elongate radiation source (e.g. an ultraviolet radiation lamp such as a low pressure high output ultraviolet radiation lamp) disposed within a protective sleeve (e.g. made from a radiation transparent material such as quartz and the like). In some case it may be possible (and preferred) to utilize a radiation source without a protective sleeve (e.g., photon emitting lamps without a protective sleeve). As can be seen, particularly with reference to FIG. 5 , intermediate region 118 of inlet transition zone 114 has a transverse direction the same as fluid treatment zone 120 . The sides of intermediate region 118 of inlet transition zone 114 are tapered as shown in FIG. 4 . This arrangement allows for the tapering transition on the one hand while leaving adequate room for the apex of the array of radiation sources on the other hand. The radiation source assemblies in banks 126 and 128 have longitudinal axes which are angled with respect to the direction of fluid flow (arrow A) through fluid treatment zone 120 . The result is an apex-shape orientation of radiation source assemblies in banks 126 and 128 as clearly seen in, for example, FIG. 4 . The angle .alpha. between the respective longitudinal axes of radiation source assemblies in banks 126 and 128 is preferably in the range of from about 15.degree. to about 170.degree., more preferably from about 35.degree. to about 120.degree., even more preferably from about 50.degree. to about 120.degree., most preferably from about 60.degree. to about 90.degree. It will be appreciated by those of skill in the art that, with a fixed length radiation source, the angle will determine the cross sectional area of the reactor. Further, although not illustrated specifically in the drawings herein, it is preferred and desirable to incorporate in the present fluid treatment system a cleaning device for removing fouling materials from the exterior of the radiation source assemblies in banks 126 and 128 . An example of incorporating a cleaning device in the present fluid treatment system is illustrated schematically in FIG. 9 . As shown, it is possible to incorporate the cleaning device as a sleeve which travels in a reciprocal manner over the exterior of the radiation source assemblies. As shown, a cleaning device 28 is provided for each radiation source assembly in the form of a movable sleeve. In the illustrated embodiment, cleaning device 28 is “parked” such that it is downstream of support post 134 . The nature of cleaning device 28 is not particularly restricted. See, for example, U.S. Pat. No. 6,342,188 [Pearcey et al.] and U.S. Pat. No. 6,646,269 [Traubenberg et al.], both assigned to the assignee of the present invention. With reference to FIG. 6 , there is illustrated the side elevation, in schematic, of an arrangement of radiation source assemblies. Generally, this arrangement is the same as the V-shaped configuration discussed above. As shown, there is a row B of 6 radiation source assemblies disposed vertically in the fluid treatment zone. Between each pair of radiation source assemblies in row B, there is a pre-determined spacing C. As illustrated, radiation source assemblies downstream of row B are arranged in a manner whereby more than two subsequent downstream vertical rows of radiation source assemblies are required to partially obscure pre-determined spacing C. In other words, if one were to view the array of radiation source assemblies along arrow D the flow of fluid through pre-determined spacing C would be obstructed as a result of the arrangement of at least two rows of radiation source assemblies downstream of row B. It will be appreciated by those of skill in the art that, with a relatively large enough number of rows B, the staggered radiation source assemblies per row can completely obstruct the line of vision through the staggered array whereas with fewer radiation source assemblies, the line of sight would not be completely obstructed. As shown, the array of radiation source assemblies includes a quartet of boundary lamps disposed in the same plain at the outer edges of the staggered array, in this embodiment, of the fluid treatment zone. As further illustrated, the array of radiation source assemblies is arranged to define repeating pattern consisting of a parallelogram containing four radiation source assemblies. FIG. 7 illustrates a schematic similar to the one shown in FIG. 6 with the exception that the staggering of the radiation source assemblies is different from that shown in FIG. 6 . Specifically, it will be seen that the parallelogram repeating pattern referred to above with reference to FIG. 6 does not appear in the arrangement shown in FIG. 7 . Otherwise, FIG. 7 does illustrate the use of boundary lamps and the staggering of subsequent rows of radiation source assemblies such that the gap between pairs of radiation source assemblies in the first row is effectively filled by more than two subsequent rows as one views the array of radiation source assemblies from one end of the fluid treatment zone. FIG. 8 a is a schematic similar to that shown in FIG. 4 with the exception that two arrays 120 a and 120 b are used in the fluid treatment zone. As shown, each of array 120 a and array 120 b is a V-configuration similar to that shown in FIGS. 1-4 described above. FIG. 8 b is a schematic similar to that shown in FIG. 4 with the exception that four arrays 120 a , 120 b , 120 c and 120 d are used in the fluid treatment zone. As shown, each of array 120 a , 120 b , 120 c and 120 d is a V-configuration similar to that shown in FIGS. 1-4 described above. Preferably, each array 120 a , 120 b , 120 c and 120 d is arranged as described below with reference to FIG. 16 . In FIG. 8 b , it is preferred that the spacing between adjacent arrays 120 a , 120 b , 120 c and 120 d is equal to the spacing between adjacent pairs lamps in a column of lamps in an array (e.g., dimension X in FIG. 16 ). With reference to FIG. 10 , there is shown, in schematic, a radiation source assembly E which is disposed such that its longitudinal axes is orthogonal to the direction of fluid flow shown by arrow A—such an orientation is known from the prior art. As will be understood by those of skill in the art, this orientation of radiation source assembly E presents a circular cross-section to the direction of fluid flow shown by arrow A. Consequently, vortices are generated downstream of radiation source assembly E which are random and wide-angled. The result of this is forced oscillation of radiation source assembly E and/or other radiation source assemblies in the vicinity of radiation source assembly E which can lead to breakage thereof. With reference to FIG. 11 , there is shown, in schematic, a radiation source assembly F orientated in the manner described above with reference to FIGS. 1-4 . In this orientation, radiation source assembly F presents an oval or ellipse cross-section to the direction of the flow of fluid depicted by arrow A. Consequently, vortices downstream of radiation source assembly F are more regular and less likely to create the forced oscillation disadvantages that can result in breakage of the radiation source assembly. With reference to FIGS. 12-15 , there is illustrated schematic end views (i.e., view thorough the fluid treatment zone) of a number of embodiments of the staggered/parallel orientation referred to above. In FIGS. 12-15 , reference is made to “First”, “Second” and “Third” ( FIG. 13-15 ) when describing a “Bank” of radiation source assemblies. These terms are intended to denote serial placement of a given “Bank” in a direction from an upstream portion to a downstream portion of the fluid treatment zone. Thus, with reference to FIG. 12 , it will be seen that the rows of radiation source assemblies in the “First Bank” are staggered in two respects: (i) there is a stagger with respect to a downstream (or upstream) “Second Bank” of radiation source assembles, and (ii) there is a stagger between adjacent rows of radiation source assemblies in the “First Bank”. The arrangement of radiation source assemblies shown in FIG. 12 is particularly well suited for application in fluid treatment systems such as those described in the Maarshalkerweerd #2 patents. With reference to FIG. 13 , there is illustrated another schematic arrangement of radiation source assemblies in accordance with the staggered/parallel orientation referred to above. The arrangement of radiation source assemblies shown in FIG. 13 is particularly well suited for application in open channel fluid treatment systems such as those described in the Maarshalkerweerd #1 Patents. As shown, the arrangement of radiation source assemblies comprises a First Bank, a Second Bank and a Third Bank. It will be seen that, in an end view, for an adjacent trio of rows of radiation source assemblies in the First Bank, the Second Bank and the Third Bank, each of the First Bank and the Third Bank is: (i) staggered with respect to the Second Bank, and (ii) non-staggered respect to the other. The resulting orientation of radiation may be characterized by: (i) an equilateral triangle though the axis of radiation source assemblies in adjacent rows of the same Bank, and (ii) an equilateral triangle though the axis of radiation source assemblies in an adjacent trio rows of the First Bank, the Second Bank and the Third Bank. With reference to FIGS. 14 and 15 , there are illustrated schematic views of arrangements of radiation source assemblies similar to that discussed above with reference to FIG. 13 . In FIG. 13 , from the left hand reactor wall, the positioning of rows is: First Bank followed by Second Bank followed by Third Bank. In FIG. 14 , from the left hand reactor wall, the positioning of rows is: Second Bank followed by Third Bank followed by First Bank. In FIG. 15 , from the left hand reactor wall, the positioning of rows is: Second Bank followed by First Bank followed by Third Bank. With reference to FIG. 16 , there is illustrated a highly preferred arrangement of radiation source assemblies for use in the present fluid treatment system. Thus, in FIG. 16 , there is illustrated a schematic arrangement (e.g., specific details support, electrical connection and sealing of the radiation source assemblies has been omitted for clarity) of the radiation source assemblies shown in a side elevation of the fluid treatment system. Each oval in FIG. 16 denotes an opening in a wall of the fluid treatment system through which an end of the radiation soured assembly would emanate. It is preferred to arrange the radiation source assemblies in a manner such as illustrated above with reference to any of FIGS. 1-4 , 8 a and 8 b. With continued reference to FIG. 16 , there is illustrated a fluid treatment system 200 comprising, in a preferred embodiment, an enclosed (or closed) fluid treatment zone having a reactor ceiling 205 and a reactor floor 240 . Disposed between reactor ceiling 205 and reactor floor 240 are four modules A, B, C and D of radiation source assemblies. Modules A, B. C and D are substantial the same. Those with skill in the art will appreciate that, while four modules are illustrated in FIG. 16 , it is possible to use fewer or greater then four depending on the volume of fluid being treated, the quality of fluid being treated and other factors within the purview of a person skilled in the art. Each of modules A, B, C and D comprises four rows 210 , 215 , 220 and 225 . As shown, rows 215 and 220 each comprise a series of radiation source assemblies where each adjacent pair of radiation source assemblies in each row are spaced apart in a substantially uniform manner. Specifically, the distance between all adjacent pairs of radiation source assemblies in row 215 is X as is the distance between all adjacent pairs of radiation source assemblies in row 220 . With reference to rows 210 and 225 , it will be seen that most of the pairs of adjacent radiation source assemblies are equally spaced and, in a preferred embodiment, the spacing is X as shown with respect of rows 215 and 220 . However, rows 210 and 225 also contain a pair of radiation source assemblies with a spacing Y that is less then spacing X used elsewhere in rows 210 and 225 . As will be seen with reference to module A, a quartet of radiation source assemblies including a single radiation source assembly from each of rows 210 , 215 , 220 and 225 is arranged to define a parallelogram repeating unit E. Parallelogram repeating unit E comprises all of the radiation source assemblies in module A except the pair of boundary radiation source assemblies 230 . Those with skill in the art will appreciate that it is possible to use parallelogram repeating pattern E to scale up or scale down module A (or one or more modules B, C and D) depending on factors such as the volume of fluid being treated and the like. Another feature of module A is the so-called stagger order of the radiation source assemblies appearing in the parallelogram repeating unit E. As shown, progressing from reactor ceiling 205 to reactor floor 240 , for a given parallelogram repeating pattern E, the following is the order of rows from which the radiation source assembly is derived: 210 , 220 , 215 and 225 . In other words, for a given parallelogram repeating unit E, the sequence of rows progressing from an upstream portion of the fluid treatment zone to a downstream portion of the fluid treatment zone (i.e., 210 , 215 , 220 and 225 ) differs from the sequence of rows progressing from reactor ceiling 205 to reactor floor 240 (i.e., 210 , 220 , 215 and 225 ). This results in the parallelogram repeating unit E and provides advantageous in the ability to efficiently treat fluid passing through fluid treatment system 200 . Specifically, this so-called stagger order allows for scalability and modulation of the power used to operate the fluid treatment system. By this it is meant that, using a stagger order such as parallelogram repeating pattern E, it is possible to lower the power consumption or even turn off of the power to certain rows of radiation source assemblies within a given module (e.g., one, some or all of modules A, B, C and D) to account for factors such as fluid transmittance, type and/or concentration of a particular contaminant and the like. For example, it is possible to operate the radiation source assemblies in rows 210 and 215 at full power while lowering or turning off the power to the radiation source assemblies in rows 220 and 225 . This allows for advantageous fining tuning of the overall power consumption of the fluid treatment system (power consumption is usually the single largest operating expense associated with the fluid treatment system). Such fine tuning would be difficult to achieve if the sequence of rows progressing from an upstream portion of the fluid treatment zone to a downstream portion of the fluid treatment zone (i.e., 210 , 220 , 215 and 225 ) was the same as the sequence of rows progressing from reactor ceiling 205 to reactor floor 240 (i.e., 210 , 215 , 220 and 225 ). In this situation, to modify power consumption, it would be necessary to turn off entire modules within the fluid treatment zone resulting in relatively uneven fluid treatment. With further reference to FIG. 16 , it can be seen that the spacing V between rows 210 and 215 is the same as the spacing between rows 220 and 225 . It can be further seen that the spacing Z between rows 215 and 220 is greater that spacing V. In certain cases, it may be desirable for spacing V and spacing Z to be substantially the same. Still further, there is a spacing T between adjacent modules A, B, C and D. It can be seen that spacing T is greater than spacing V. In certain cases, it may be desirable for spacing V and spacing T to be substantially the same. Further, in certain cases, it may be desirable for spacing V, spacing Z and spacing T to be substantially the same. While this invention has been described with reference to illustrative embodiments and examples, the description is not intended to be construed in a limiting sense. Thus, various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description. For example, while the illustrated embodiments described above with reference to the accompanying drawings relate to a fluid treatment system comprising a fluid treatment zone having a closed cross-section, it is possible and, in some cases, preferred to implement the present fluid treatment system with a fluid treatment zone having an open or other non-closed cross-section (e.g., in an open channel system such as is described in the Maarschalkerweerd #1 Patents referred to above). Still further, it is possible and, in some cases, preferred to implement the present fluid treatment system with a fluid treatment zone having an semi-enclosed cross-section (e.g., such as is described in the Maarschalkerweerd #2 patents referred to above). Still further, it is possible and, in some cases, preferred to implement the present fluid treatment system with a fluid treatment zone that employs so-called “hybrid” radiation source modules (e.g., such as described in United States patent application publication No. 2002/113021 [Traubenberg et al.] or in International Publication Number WO 04/000,735 [Traubenberg et al.]). as stated above, it is possible to incorporate a mechanical or chemical/mechanical cleaning system to remove fouling materials from the exterior of the radiation source assemblies as described various published patent applications and issued patents of Trojan Technologies Inc. Still further, a variety of conventional sealing systems made of a variety of materials may be used in the present fluid treatment system. The selection of sealing materials and the placement thereof to obtain a sufficient seal is not particularly restricted. Still further, it is possible to modify the illustrated embodiments to use weirs, dams and gates upstream, downstream or both upstream and downstream to optimize fluid flow upstream and downstream of the fluid treatment zone defined in the fluid treatment system of the present invention. Still further, it is possible to modify the illustrated embodiments to include sloped and/or stepped channel surfaces such as is disclosed in International Publication Number WO 01/66469 [Brunet et al.]. Still further, it is possible, to modify the illustrated embodiments to include mixers or mixing elements on the walls of the channel of the fluid treatment system and/or the radiation source module, for example as taught in one or more of U.S. Pat. No. 5,846,437 [Whitby et al.], U.S. Pat. No. 6,015,229 [Cormack et al.], U.S. Pat. No. 6,126,841 [Whitby et al.], U.S. Pat. No. 6,224,759 [Whitby et al.] and U.S. Pat. No. 6,420,716 [Cormack et al.], and in International Publication Number WO 01/93995 [Brunet et al.]. Such mixers or mixing elements (sometimes also referred to in the art as “baffles”) can be used to supplement or replace the use of so-called boundary lamps or boundary radiation source assemblies discussed above. Still further, it is possible to modify the illustrated embodiments to provide multiple banks of radiation source assemblies in hydraulic series. Still further, it is possible to modify the illustrated embodiments to utilized a radiation source assembly comprising a plurality of radiation sources disposed in a protective sleeve (i.e., sometimes referred to in the art as a “lamp bundle”). Still further, it is possible to modify the illustrated embodiments in FIGS. 1 and 2 such that banks 126 and 128 are disposed serially rather than in a side-by-side relationship (of course the dimensions of other elements of the fluid treatment system would need to be modified accordingly). It is therefore contemplated that the appended claims will cover any such modifications or embodiments. All publications, patents and patent applications referred to herein are incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety.

A fluid treatment system having: an inlet; an outlet; and a fluid treatment zone disposed therebetween. The fluid treatment zone has: (i) an elongate first radiation source assembly having a first longitudinal axis, and (ii) an elongate second radiation source assembly having a second longitudinal axis. The first and second longitudinal axes are non-parallel to each other and to a direction of fluid flow through the treatment zone. The present fluid treatment system can treat large volumes of fluid (e.g., wastewater, drinking water or the like); it requires a relatively small “footprint”; it results in a relatively lower coefficient of drag resulting in an improved hydraulic pressure loss/gradient over the length of the treatment system; and it results in relatively lower (or no) forced oscillation of the radiation sources thereby mitigating breakage of the radiation source and/or protective sleeve (if present).

CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims priority to U.S. Provisional Patent Application Ser. No. 61/602,346, entitled “Deck System and Components”, filed Feb. 23, 2012 and U.S. patent application Ser. No. 13/465,512, entitled, “Deck System and Components”, filed May 7, 2012, the entire disclosures of which are hereby incorporated by reference in its entirety. BACKGROUND [0002] 1. Field of the Invention [0003] Various aspects of the invention relate to structures such as floors, roofing and exterior decking, and more specifically, relate to deck boards, deck planks, porch boards, flooring, the connection of adjacent boards to each other, the connection of the end of boards to each other, and various accessories used with such structures. [0004] Certain aspects of the invention relate to the management of rain water & melting snow to keep the underside of a deck system substantially dry, providing for storage of articles and the ability to have a first floor patio/deck area underneath it without rain water affecting the enjoyment of the space or reaching the foundation of the house. [0005] 2. Description of Related Art [0006] Deck systems are in wide use in both residential and commercial applications. Some deck systems consist of simple wooden boards having a rectangular cross-section each arranged longitudinally parallel to each other onto a supporting structure. Similar systems are in use with the deck boards being made of manmade material such as a composite or plastic based material. [0007] These known systems sometimes have several disadvantages. For example, the parallel boards usually are spaced apart from each other laterally to some degree, and even if the deck boards are abutting each other along their length, there is generally still some type of gap between them. This gap between the long edges of the boards allows water to pass through. Thus, when natural rain water or a cleaning water, spilled water, melting snow or other liquid contacts the top surface of the deck boards, it will typically leak down through between the deck boards. This can be undesirable in situations where it is preferred that the region under the deck surface be kept dry. Such situations include structures having a deck surface on an upper floor and a residential area on a lower floor beneath the deck surface. Other situations where it is preferred that the region under the deck surface be kept dry include decks having a dirt surface beneath the deck surface. By keeping the dirt surface beneath the deck surface dry, the resident may prevent the dirt beneath the deck surface from becoming a haven for insects and weeds. In other commercial or industrial uses, it is desirable to keep liquids on the upper surface from inadvertently dripping to the lower area. In addition, where deck boards are also end-to-end, there is typically a space between the end surfaces of the deck boards. In some instances a relatively wide space is left between the ends of the deck boards in order to allow for a thermal expansion and contraction of boards placed end to end. This gap also can allow for undesirable fluid leakage or liquid leakage under the deck as described above. [0008] Another disadvantage of some deck boards is that in some instances it is necessary to screw the deck boards down to the supporting structure and in a conventional rectangular cross-section board, the screw heads are exposed on the top surface which may be undesirable for cosmetic or other reasons. SUMMARY [0009] In light of the present need for improved decking systems and accessories, a brief summary of various embodiments is presented. Some simplifications and omissions may be made in the following summary, which is intended to highlight and introduce some aspects of the various embodiments, but not to limit the scope of the invention. [0010] Various embodiments disclosed herein can relate to new and useful decking board constructions. For example, the decking board may feature an extruded cross-section having a generally tongue-and-groove mating fit between lateral and adjacent boards. In various embodiments, the decking board may be a symmetrical, two sided product, with each side optionally having different pattern or color, thereby creating two products in one. One side of the board may feature an upwardly directed U-shaped hook next to a downwardly directed groove or channel. The other side of the decking board may have a complimentary, but opposite shaped, downwardly directed U-shaped hook adjacent to an upwardly directed groove or channel. When the boards are interlocked side-to-side, each hook will mate into each groove thereby providing secure connection between the boards. Further, since the tongues and grooves are overlapping, there is no vertical path for water on the top of the board to pass in between the boards. In various embodiments, the upwardly directed U-shaped tongue forms a primary water channel to collect and direct water along the length of the structure to the end of the structure. [0011] In another aspect, a flashing element may be provided to act as a butt joint to connect the butt ends of the boards. The flashing element has a complimentary shape to the upper surface of the board, and can reside in longitudinal grooves that are cut into the butt ends of the boards. The flashing can also be a sharpened and or hardened element which is installed by tapping the first sharp end of the flashing element into the relatively soft edge of the first board, and then bringing the second board into contact with the second end of flashing element and then tapping the far end of the second board so that the second edge of the flashing element is pushed into the relatively soft first end of the second board. When installed, the flashing prevents water from passing downward between the butt ends of the boards. In various embodiments, the flashing allows for expansion and contraction of the boards due to fluctuations between hot and cold environments. In one embodiment, a metal flashing that taps into place can be held in place by an integral structure that then presses or affixes onto one or more edges of the board or boards and holds it in place to make assembly easier. [0012] Another embodiment of the butt joint involves installation of a polymer part having a primarily “V-shaped” profile that flexes. The polymer part having a primarily “V-shaped” profile is installed between the butt ends of the planks. The flexing of the polymer part ensures a tight fit is maintained during expansion and contraction of the planks. [0013] In another aspect, the boards may feature one or more longitudinal hollow regions. The longitudinal hollow regions may accept a heating element such as a heatable wire or a heating fluid conduit or hose. Other heating elements such as radiant heating elements or hot air containing passages may reside in or be part of the interior of the board. In some instances, a particular longitudinal hollow shape may be provided, or the heating elements may be embedded in the structure during manufacture. [0014] In addition, at least one flexible member may be added inside the tongue and groove area on either part to align the planks when originally installed tightly together and to also withstand the expansion and contraction of the planks in the widthwise direction during hot and cold weather. Initially, at points of contact between adjacent tongues and grooves of adjacent boards, a bumper protrusion may be provided on one board which will frictionally engage with a complimentary groove on the other board. [0015] In another embodiment, a gutter may be added to the perimeter of the deck surface to collect the water that is shed from the surface and direct it downwards in a controlled fashion to connectors connecting to a leader which guides water away from the underside of the deck. [0016] In another embodiment, the addition of a perimeter element may take the form of a bull nose type extrusion that provides some protection to the end boards when objects come in contact with the end of the deck. This may be particularly useful where the ends of the deck may come in contact with vehicles such as carts or, where the deck is being used as a dock and may come in contact with watercraft. [0017] In another embodiment, the decking board comprises first and second longitudinal sides. The first longitudinal side has a male projecting member with an upwardly directed rib and the second longitudinal side has a female slot defining a downwardly directed rib. The boards can be interlocked adjacent each other with the upwardly directed rib snapped past the downwardly directed rib to form a frictional engagement therebetween. A central main body portion is disposed in longitudinal sides. [0018] In another embodiment, the decking board comprises a first longitudinal side having an extension member including a first surface and an opposing second surface, the first surface including an upwardly projected abutment defining a first lip. The second surface has a recess formed therein. The second longitudinal side includes a first portion defining a tongue and a second portion including a second lip. The tongue includes a first flexible member extending generally upward from the first portion. The second lip includes a second flexible member extending generally downward from the second portion. [0019] a main central body disposed intermediate to the first longitudinal side and second side; [0020] wherein the first portion and second portion of the second longitudinal side define a cavity therebetween to receive an extension member of an associated decking board therein. [0021] In another aspect, a dock board may be provided in the form of a relatively simple dock board extrusion. BRIEF DESCRIPTION OF THE DRAWINGS [0022] In order to better understand various exemplary embodiments, reference is made to the accompanying drawings, wherein: [0023] FIG. 1A shows various elements of a decking system, including decking boards and a flashing element. [0024] FIG. 1B is a cross-section of the embodiment of FIG. 1A . [0025] FIG. 1C is a detailed view of a part of the cross-section of FIG. 1B . [0026] FIG. 1D shows a cross-section of one embodiment of a decking board. [0027] FIG. 1E shows a cross-section of another embodiment of a decking board. [0028] FIG. 1F shows a cross-section of yet another embodiment of a decking board. [0029] FIG. 2A shows a number of decking boards according to the embodiment of FIG. 1F in an installed condition. [0030] FIG. 2B shows additional details of the system of FIG. 2A . [0031] FIG. 2C shows a number of decking boards according to the embodiment of FIG. 1E in an installed condition. [0032] FIG. 3A illustrates a drain and gutter system. [0033] FIG. 3B is an exploded view of the system of FIG. 3A . [0034] FIG. 3C is a further exploded view of the system of FIG. 3A . [0035] FIG. 3D depicts components of the drain and gutter system. [0036] FIG. 3E shows a drain and gutter system corner connector [0037] FIG. 4 shows a cross-section of a component of the drain and gutter system having a bull nose profile. [0038] FIG. 5 shows a simplified decking board in the form of a dock plank. [0039] FIG. 6 shows a bull nose component for mounting to the end a deck or dock system. [0040] FIGS. 7A and 7B show polymer parts which aid in connecting planks of FIG. 1 in an end-to-end relationship. [0041] FIG. 8A is a cross-sectional view of another embodiment of a decking board. [0042] FIG. 8B shows two decking boards according to FIG. 8A joined together. [0043] FIG. 9A is a cross-sectional view of another embodiment of a decking board. [0044] FIG. 9B shows two decking boards according to FIG. 9A joined together. [0045] FIG. 10A is a cross-sectional view of another embodiment of a decking board. [0046] FIG. 10B shows two decking boards according to FIG. 10A joined together. [0047] FIG. 11A is a cross-sectional view of another embodiment of a decking board. [0048] FIG. 11B is a side view of the board of FIG. 11A . [0049] FIG. 11C is a bottom view of the board of FIG. 11A . [0050] FIG. 11D is a top view of the board of FIG. 11A . [0051] FIG. 11E is a cross-sectional view of two boards according to FIG. 11A mounted together. [0052] FIG. 12A is a cross-sectional view of another embodiment of a dock board. [0053] FIG. 12B is a side view of the dock board of FIG. 12A . [0054] FIG. 12C is a bottom view of the dock board of FIG. 12A . [0055] FIG. 12D is a top view of the dock board of FIG. 12A . [0056] FIG. 13A is a side view of a decking board system, illustrating two decking boards in locking engagement. [0057] FIG. 13B is a cross-sectional view of another embodiment of a decking board. [0058] FIG. 13C is a sectional view of the decking board of FIG. 13B , further illustrating the decking board connection and fastening component. [0059] FIG. 13D is a side view of a decking board system of FIG. 13A illustrating the attachment of plural decking boards. DETAILED DESCRIPTION [0060] Referring now to the drawings, in which like numerals refer to like components or steps, there are disclosed broad aspects of various exemplary embodiments. [0061] The board is used herein to refer to any type of longitudinal surface or substrate board. Some embodiments are referred to as decking boards, but any embodiments could be used in porches, floors, roofing or other uses as will be understood by one skilled in the art of construction components. [0062] Various embodiments disclosed herein can relate to new and useful decking board constructions. For example, the decking board may feature an extruded cross-section having a generally tongue-and-groove mating fit between lateral and adjacent boards. One side of the board may feature an upwardly directed U-shaped hook next to a downwardly directed channel. The other end of the decking board may have a complimentary, but opposite shaped, downwardly directed U-shaped hook adjacent to an upwardly directed groove. When the boards are interlocked side-to-side, each hook will mate into each groove thereby providing secure connection between the boards. Further, since the tongues and grooves are overlapping, there is no vertical path for water on the top of the board to pass in between the boards. In addition, the downwardly directed U-shaped tongue forms a water channel to collect and direct water along the length of the structure to the end of the structure. [0063] FIG. 1A depicts a deck system 10 including a plurality of decking boards 12 . Each board 12 has a downwardly directed tongue 14 which has an upwardly facing groove 16 . Located inward of the downward facing tongue 14 is a downward facing groove 18 . A reversed structure is provided on the other side of the board 12 including an upward facing tongue 20 having a downward facing channel 22 . Located inward of the upward facing tongue 20 is an upward facing groove 24 . FIG. 1A also shows the boards interconnected with each other with the downward facing tongue 14 residing in the upward facing groove 24 of an adjacent board. The farthest edge 26 of the downward facing tongue 14 slides against a resilient tab 28 . Similarly, the outer surface 30 of the board will abut against a tab 32 in an adjacent board. In the assembled system, therefore, a water collecting channel 40 is provided which appears from the upper surface of the deck as a simple downward rectangular channel. In various embodiments, the boards are symmetrical so the customer can turn the decking boards upside down while still allowing interconnection between the boards. In some embodiments, the symmetrical boards have identical patterns and colors on each side. This contributes to ease of assembly, as each board may be used with either side uppermost. In some embodiments, the symmetrical boards have different patterns or colors on each side. The presence of different patterns or colors on each side of the decking boards allows the customer to choose between two different or complementary surface styles while buying only one board item version. [0064] In another aspect, a flashing element may be provided to connect the butt ends of the boards. The flashing element has a complimentary shape to the upper surface of the board, and can reside in longitudinal grooves that are cut into the butt ends of the boards. When installed, the flashing element prevents water from passing downward between the butt ends of the boards. This is true even if a relatively wide end to end gap is selected to allow for thermal expansion and contraction. [0065] Into the end of each board is cut a slot 42 which extends a predetermined distance into the board, but not all the way through its length. The slot 42 is sized to receive the insertion of a flashing element 50 . The flashing element, therefore, resides in the slots 42 in the butt ends of boards 12 placed end to end, and prohibits any water flow between the ends of the boards. To the extent the flashing element 50 is visible between butt end gap between the boards, any liquid that contacts the flashing will be directed into a channel portion 52 of the board and will, once a certain volume of liquid is reached, be carried away by channel 40 . The flashing element 50 can be made from folded or extruded metal and may have its edges sharpened for tapping into place into slots 42 in the butt ends of the boards. [0066] In various embodiments, the flashing can be a sharpened and/or hardened element which is installed by tapping the first sharp end of the flashing element into the relatively soft end of a first board, and then bringing a second board into contact with the second end of flashing element and then tapping the far end of the second board so that the second edge of the flashing element is pushed into the relatively soft first end of the second board. In such embodiments, the presence of slots 42 in the butt ends of boards 12 is optional. [0067] A feature of the boards 12 shown in FIG. 1A is that they can be slid together along their length. That is, rather than snapping the boards in together to mate from the top, which is possible, another assembly option is to slide the boards together end to end, one next to another. Accordingly, boards can be assembled into an overlapping deck without the use of any hardware to hold the boards to each other. [0068] A device for facilitating formation of watertight butt joints is shown in FIG. 7A , It is a polymer part 700 that has a primarily “V-shaped” profile 701 that flexes during installation between the butt ends of the planks. The butt ends of the planks contact the outer surface of the “V-shaped” profile 701 . Flexing of the profile 701 ensures a tight fit is maintained during expansion and contraction of the planks. The polymer part 700 may also have a hidden tape or other sealant material to keep the butt joint in place and provide further water sealant ability. The polymer part 700 may have one or more snap provisions to hold it down in place between the ends of the planks. This “V-shaped” profile 701 directs the water that would normally have fallen between the ends of the planks into channel 702 , which fits into rain grooves 40 in the planks and bridges rain grooves in two planks in an end-to-end relationship. Channel 702 guides water into the rain groove 40 in FIG. 1A . [0069] Another embodiment of the device for facilitating formation of watertight butt joints is shown in FIG. 7B , and is a polymer part 210 that has a primarily “T-shaped” profile 711 installed between the butt ends of the planks, with the vertical member of the “T-shaped” profile 711 fitting between the butt ends of the boards. The polymer part 710 may have a sealant or tape used to keep it in place and may have one or more snap provisions to keep it in place between the ends of the deck planks. The horizontal member of the “T-shaped” profile 711 covers the top surface of the planks and has a “U-shaped” extension forming channel 712 that fits on top of and spanning the space between the ends of the rain grooves 40 of the planks whose ends are being joined. This embodiment may or may not have some sealant, tape or snap fit to help hold it into place. [0070] In an alternate embodiment, a device for facilitating formation of watertight butt joints is a polymer part 710 that has a primarily “I-shaped” profile installed between the butt ends of the planks, with the vertical member of the “I-shaped” profile fitting between the butt ends of the boards. The “I-shaped” profile has an upper horizontal member which covers the top surface of the planks and has a “U-shaped” extension forming a channel that fits on top of and spans the space between the ends of the rain grooves 40 of the planks whose ends are being joined. The “I-shaped” profile has a lower horizontal member. The butt ends of the boards fit between the upper and lower horizontal members. [0071] Device 700 and 710 for facilitating formation of watertight butt joints may have a snap fit feature for securing them between boards. [0072] Returning to FIG. 1A , the boards may also be assembled by installing a first board having an upwardly facing groove 24 , and then connecting a second board having a downwardly facing tongue 14 to the first board. This is done by placing the downwardly facing tongue 14 of the second board over the already installed first board. Then the second board's downwardly facing tongue 14 is aligned over the first board's upwardly facing groove 24 and the second board is dropped down onto and over the top of the edge of the first board so tongue 14 goes into groove 24 . The second board then slides into the groove 24 of the first board, tightly against the first board, so that the edge 26 of the downward facing tongue 14 slides against a resilient tab 28 in groove 24 . The edge 26 of the downward facing tongue 14 makes tight contact with tab 28 . This creates a perfect alignment between the boards as the installer puts screws down onto the surface of grooves 24 , securing the boards in place. This also contributes to the water tightness of channel 40 , which also has upwardly facing and downwardly facing interconnecting elements. The resilient tab 28 allows for thermal based expansion of the boards after assembly. It may be desirable to mount the boards to an underlying structure (this will be described further with reference to FIG. 2A using the board of FIG. 1F ). The board of FIG. 1A provides a conveniently accessible mounting location for such screws through the surface of the groove 24 , which may or may not be pre-drilled with holes 63 for ease of installation. [0073] In another aspect, the boards may feature one or more longitudinal hollow regions 62 . The longitudinal hollow regions may accept a heating element such as a heatable wire or a heating or cooling fluid conduit or hose. Other thermal elements such as radiant heating elements or hot air containing passages may reside in or be part of the interior of the board. In some instances, a particular longitudinal hollow shape may be provided, or the heating elements may be embedded in the structure during manufacture. [0074] The board 12 also includes a main body region 60 . This main body region 60 may be solid or may be provided with one or more hollow regions 62 . The hollow region 62 may provide a number of benefits including, for example, reducing the weight of the board compared to a solid board. Further, the hollow region 62 may allow for the insertion of heating devices. The board depicted in FIG. 1A also features stiffening ribs 64 . These ribs 64 can provide stiffening, and can also maintain heater cables separate from each other if they are installed in back and forth rows. [0075] It is also noted that the openings 62 may have a wide variety of shapes as are shown in the other figures, and other cross-sectional shapes. In addition to or instead of containing heating elements, other items such as wires for power outlets, speakers, dog fences, or other wire based products may be passed through the hollow portions 62 . [0076] In another aspect, a flexible assembly tab or member such as tab 28 , 32 and 128 may be provided on the boards near the tongue and groove region to provide a firm frictional contact between the adjacent tongues and grooves and to align the boards during assembly. Initially, at points of contact between adjacent tongues and grooves of adjacent boards, a bumper protrusion may be provided on one board which will frictionally engage with a complimentary groove on the other board. It is also noted that tabs 28 , 32 and 128 provide a stop feature during the assembly process, but further allow for lateral expansion and contraction of the boards during temperature extremes. The tabs 28 , 32 nd 128 may be referred to as flexible members. The resilient or flexible members may provide for alignment and frictional engagement. They may thus be in a slightly bent configuration in the assembled state. However the tabs may also be sacrificial in that they are designed to be breakable or frangible, that is, they may break off upon application of sufficent force during installation of adjacent boards. [0077] FIG. 1D shows a decking board having a different cross-section from FIG. 1A . This board 112 may be thought of as having a tongue 114 which projects into a groove 124 . An upward facing channel 116 is provided that will function similarly to the channel 16 described above. A resilient tab 128 is also provided. Instead of an upwardly directed tongue, this embodiment features a laterally extending tongue 120 . The tongue 120 can provide for a screw location similar to that in the channel 24 and may or may not be pre-drilled with holes for easy assembly. The tongue 120 can also nest in a rectangular notch 118 provided on the other side of an adjacent board. An additional relief area 119 is provided on the lower surface of the tongue 114 which permits clearance for a screw head. The embodiment of FIG. 1D features a single central hollow area 162 . FIG. 1D also schematically depicts heating elements 170 in hollow portion 162 . [0078] FIG. 1E shows a deck board similar to the board of FIG. 1D , but without the central hollow area 162 . FIG. 1E shows a decking board having a tongue 114 which projects into a groove 124 . A resilient tab 128 is also provided. This embodiment features a laterally extending tongue 120 . The tongue 120 can nest in a rectangular notch 118 provided on the other side of an adjacent board. The embodiment of FIG. 1D optionally includes a pivot bump 117 , and a pocket 126 . Pocket 126 is adapted to receive a mounting screw. However the pocket 126 can also serve as a track for accepting a longitudinal heating wire 130 as shown. [0079] FIG. 1F shows a deck board having a similar outer profile to that of FIGS. 1D and 1C , but having a central hollow opening 162 that includes stiffening ribs 164 . FIG. 1D also illustrates that the lower surface of the hollow region 162 has a parabolic concave upward shape to reflect heat upwards. A fastener 66 is shown being screwed into hole 63 for mounting. [0080] FIGS. 2A and 2B show additional details utilizing the board of FIG. 1F . In this embodiment, the board of FIG. 1F has been further provided with a bump/rib 115 and a corresponding bump/rib 125 . Instead of both items 115 and 125 being projecting bumps, one or the other could be a small groove notch, dimple or detent. It will be appreciated that as shown in the lower portion of FIG. 2A , the bumps/ribs 115 and 125 can engage each other to enhance the frictional connection of adjacent boards. Another bump or protrusion 117 may be placed at the edge of the bottom surface next to 118 . This bumper creates a pivot point for the plank so that when fastening the board at area 120 , the wall tongue 114 is pushed upwards to create a tight fit between the seal elements 115 & 125 . Further, FIG. 2A depicts installation screws being placed through the laterally extending tongues 120 . [0081] In this embodiment, a top surface 111 of each board 112 has a slightly crowned surface to direct water towards the water channels 140 between the boards. FIG. 2A also shows further details of the interaction between the bump/ribs 115 and 125 , and screws 127 . [0082] FIG. 2C shows an embodiment in which the board has been further provided with a bump/rib 115 and a corresponding bump/rib 125 . In the embodiment of FIG. 2C , the boards are provided with pockets 126 , and are assembled so that pockets 126 of the boards are aligned under tongues 114 of an adjacent board. The water channel 140 defined by tongue 114 of the adjacent board is thus positioned above pocket 126 . Pocket 126 is provided with heating wire 130 . Heating wire 130 provided in one board thus serves to heat channel 140 defined by tongue 114 of the adjacent board. Channel 140 is a groove for carrying rainwater. Heating wire 130 serves to prevent rainwater or melting snow in channel 140 from freezing. [0083] At the end of a board, the wire 130 may be bent and wrapped around the end of the plank to an adjacent plank. The wire then fits into pocket 126 on the adjacent plank, and travels longitudinally along the adjacent plank. Notches 131 may be provided at the ends of the boards to guide the wire from one plank to another. Heating wire 130 can be a cylindrical wire or a flat or rectangular wire having two opposed major surfaces and two opposed edge surfaces. If a flat wire is used, then the wire should be arranged so that the opposed major surfaces are vertical, i.e., perpendicular to the upper surface of the boards. If the opposed surfaces are horizontal, it is more difficult to bend the wire at the end of the plank. [0084] Pocket 126 and heating wire 130 may also be installed in the outer edge of tongue 114 or in groove 124 . Each of these locations places the heating wire in proximity to channel 140 , allowing the heating wire to heat water in the channel. [0085] In another aspect, a drain system may be provided at the longitudinal end of a deck that is made up of adjacent boards. The drain system may include a main T-downspout piece which collects and directs water to a leader, and individual adjacent gutter pieces that connect to the T-downspout. These can be mounted at the ends of the boards on the supporting structure. [0086] FIGS. 3A , 3 B, 3 C and 3 D depict various components of a gutter system. The gutter system can be used with any deck that can direct and shed surface water, including the decking systems described herein. The gutter system generally includes a main T-downspout 210 and adjacent gutter pieces 212 . The main T-downspout 210 can connect with a leader downspout 214 . The gutter portions 212 may feature an outwardly curved projecting shape 212 a which may provide some bumper protection for the end of the overall decking structure and provide a pleasing appearance by hiding the cut edges of the planks and hiding the heater wire that may be installed and running through and between each plank. Such a rounded outward portion may also be provided on the main T-downspout (although not shown) or this feature may be provided by a separate cover 216 that can be mounted along with T-downspout to cover it as shown. FIG. 3 illustrates these components and further illustrates a corner piece 318 . [0087] In another embodiment, the gutter may form a bull nose type extrusion that provides some protection to the end boards when objects come in contact with the end of the deck. This may be particularly useful where the ends of the deck may come in contact with vehicles such as carts or, where the deck is being used as a dock and may come in contact with watercraft. FIG. 4 shows a cross-section of a bull nose structure 400 that can provide a relatively simple gutter and/or bumper item that may be mounted on the edge and the end of a deck system. Alternatively, the lower portion of this type gutter extrusion can be made of various lengths so as to be useful for cutting off and using as a trim board in other areas of the deck as needed. [0088] In another aspect, a dock board may be in the form of a relatively simple dock board extrusion. FIG. 5 shows a deck board in the form of a relatively simple dock plank. This plank 500 features a relatively flat top surface, tilted sides 512 , and upwardly directed recesses 514 . The recesses 514 may assist with saving weight by still providing longitudinal bending strength. [0089] In another aspect, a bull nose structure may be provided that does not provide water gutter features, but rather provides a projecting cushion structure at the end of the deck similar to the bull nose described above. FIG. 6 depicts a bull nose structure that can be used similar to the bull nose of FIG. 4 . However, this structure has a different cross-sectional shape with structure 600 has a different cross-sectional shape including a mounting tab 612 , and a rounded compressible projection 614 that has a central lap 616 . [0090] Any or all of the various deck boards, dock boards, downspouts, gutters or bumpers and other components can be manufactured from any suitable material. In many embodiments, the various items can be manufactured by extrusion methods. Any suitable extrudable material may be used. In some embodiments the boards can be manufactured using a compression molding process. In some examples, the items may be manufactured, by extruding or otherwise, from hydrophobic polymers, i.e., PVC or polyolefins, and hydrophobic coconut coir fibers which have been treated to remove coconut coir therefrom. In various embodiments, the composite items may be manufactured without any step chemically modified coconut coir fibers. However, the disclosure herein is not limited to the use of coconut based materials. For example, as an alternative to coir fibers, extruded materials may include ramie or bamboo fibers to reinforce polymeric products. In other embodiments, the materials may simply be extruded or molded from polymeric and/or wood based composite extrudable or moldable materials. Simple plastics may also be used. Further, it may be preferable to manufacture the flashing of a metal such as stainless steel or extruded metals. [0091] The decking boards may be made by extrusion of a thermoplastic material, i.e., polyester, polyvinyl chloride, or polyolefin, preferably polyethylene or polypropylene. The thermoplastic material may contain a filler, including organic fillers such as wood powders, wood fibers, and coir fibers; inorganic fillers, such as glass fibers, carbon fibers, mineral fibers, silica, alumina, titania, carbon black, nitride compounds, and carbide compounds. The decking boards may be uncoated, or coated with a decorative coating of paint. The decking boards may be coated with a protective coating. The protective coating may be applied by coating a mixture of monomers and/or oligomers on the completed board, and then curing the coating to form a protective coating. [0092] Coated decking boards may also be made by coextrusion of: [0093] a core layer comprising a thermoplastic material, i.e., polyethylene or polypropylene, containing optional fillers, including organic fillers such as wood powders, wood fibers, and coir fibers; inorganic fillers, such as glass fibers, carbon fibers, mineral fibers, silica, alumina, titania, carbon black, nitride compounds, and carbide compounds; and [0094] a coating layer (such as for example PolyEthylene with additives) of a protective thermoplastic polymer. Suitable protective polymers include polyvinyl chloride; acrylic resins, i.e., poly(ethylene-co-methacrylic acid) (Surlyn®); polyester; polycarbonate; and polystyrene. [0095] In various embodiments, the coating layer contains UV stabilizers which reduce the likelihood of the core layer undergoing degradation from exposure to ultraviolet light. Such UV stabilizers include organic light stabilizers, such as benzophenone light stabilizers, hindered amine light stabilizers, and benzotriazoles; and inorganic light stabilizers. such as barium metaborate and its hydrates. [0096] In various embodiments, the coating layer contains antifungal agents which increase resistance of the board to mold and other organisms. The antifungal agents may be incorporated in the coating layer alone, or in both the core and coating layers. Useful antifungal agents for coatings include copper (II) 8-quinolinolate; zinc oxide; zinc-dimethyldithiocarbamate; 2-mercaptobenzothiazole; zinc salt; barium metaborate; tributyl tin benzoate; bis tributyl tin salicylate; tributyl tin oxide; parabens: ethyl parahydroxybenzoate; propyl parahydroxybenzoate; methyl parahydroxybenzoate and butyl parahydroxybenzoate; methylenebis(thiocyanate); 1,2-benzisothiazoline-3-one; 2-mercaptobenzo-thiazole; 5-chloro-2-methyl-3(2H)-isothiazolone; 2-methyl-3(2H)-isothiazolone; zinc 2-pyridinethiol-N-oxide; tetra-hydro-3,5-di-methyl-2H-1,3,5-thiadiazine-2-thione; N-trichloromethyl-thio-4-cyclohexene-1,2-dicarboximide; 2-n-octyl-4-isothiazoline-3-one; 2,4,5,6-tetrachloro-isophthalonitrile; 3-iodo-2-propynyl butylcarbamate; diiodomethyl-p-tolylsulfone; N-(trichloromethyl-thio)phthalimide; potassium N-hydroxy-methyl-N-methyl-dithiocarbamate; sodium 2-pyridinethiol-1-oxide; 2-(thiocyanomethylthio)benzothiazole; and 2-4(-thiazolyl)benzimidazole. [0097] The coating layer may help provide scratch resistance to the decking board surface, either by using a coating with a polymer which is harder than the core layer or through the use of certain additives. Additives which help increase scratch resistance in coatings include lubricants and very hard mineral fillers, including carbide and nitride ceramics. [0098] The coating layer may also include inorganic pigments, organic pigments, or dyes as colorants. The coating layer may be embossed with a decorative pattern, i,e., wood grain or imitation stone. [0099] In situations where a coating layer or “capcoat” is applied by coextrusion. the coating layer has a thickness of from about 0.01 to 0.25 inch, preferably from about 0.02 to 0.15 inch, more preferably from about 0.04 to 0.08 inch. The capcoat may cover the entire longitudinal surface of the board; the top and sides of the board, with the bottom surface being uncoated; or the top of the board, with the bottom surface and sides being uncoated. [0100] As discussed above, at least one flexible member may be added inside the tongue and groove area on the decking planks to align the planks to help withstand expansion and contraction of the planks. Also, a bumper protrusion may be provided on a board which will frictionally engage with a complimentary groove on another board. In various embodiments made by coextrusion of a core material and a capcoat, these flexible members and bumpers may be formed from the same material as the core material, and optionally coated with the capcoat material. In various embodiments made by coextrusion, these flexible members and bumpers may be formed from the capcoat material alone. In certain embodiments, flexible members and bumpers formed from the capcoat material have increased toughness, resistance to breakage, and flexibility, when compared to embodiments in which flexible members and bumpers are made from the core material, i.e., a wood fiber- or coir fiber-filled polyolefin. [0101] A further design for a flexible member produced from a capcoat polymer layer can be envisioned to be attached to the outside edge of the tongue portion, i.e., on the outside edge 26 of the tongue 14 , or on the outer surface of rain-groove element 40 , as seen in FIG. 1A . The flexible member produced from the capcoat polymer can thereby set the assembly gap between planks during installation. Additionally, a flexible member produced from the capcoat polymer and positioned on edge 26 may contact an inner surface of groove 24 , when boards are fitted together as in FIG. 1A . This provides a flexible water seal between boards as boards expand with heat and then contract again. [0102] A further design for a flexible member (not shown in FIG. 1C ) produced from a capcoat polymer layer can be envisioned to be attached to the outer edge of the tongue portion 114 or 116 , as seen in FIG. 1C , and adapted to contact the interior of groove 124 , as seen in FIG. 1C . Contact between flexible members produced from a capcoat polymer layer and groove 124 of FIG. 1C produces a flexible water seal. [0103] Also, a bumper protrusion may be provided on a board which will frictionally engage with a flexible member made of capcoat material on another board. The cap coat material is a tough resilient polymer, and may be used to produce watertight elements. [0104] FIG. 8A is a cross-sectional view of a board 800 having a top cap coat 801 and a lower cap coat 802 . A male side of the board 814 includes an upwardly projecting bump 816 and a lower pivot bump 817 . A female side 820 of the board includes a projecting bump 822 that can snap over and interlock with the projecting bump 816 , a flexible tap 832 , which can help hold the boards together in alignment, and accommodate for expansion of the boards, and a water drain channel 824 . Further, the female end has an open area to the inside of the flexible tab 832 which can be sized and dimensioned to receive a heating wire or cable. FIG. 8A shows the heating element 870 as having a generally vertical rectangular cross-section. [0105] FIG. 8B shows two of the boards 800 interlocked adjacent to each other. [0106] FIG. 9A is a cross-sectional view of a board 900 having a top cap coat 901 and a lower cap coat 902 . This board is narrower than that of FIG. 81 and thus may be more suitable for use as a porch board in some instances. A male side of the board 914 includes an upwardly projecting bump 916 and a lower pivot bump 917 . A female side 920 of the board includes a projecting bump 922 that can snap over and interlock with the projecting bump 916 , a flexible tap 932 , which can help hold the boards together in alignment, and accommodate for expansion of the boards, and a water drain channel 924 . Further, the female end has an open area to the inside of the flexible tab 932 which can be sized and dimensioned to receive a heating wire or cable. FIG. 9A shows the heating element 970 as having a generally vertical rectangular cross-section. [0107] FIG. 9B shows two of the boards 900 interlocked adjacent to each other. [0108] FIG. 10A is a cross-sectional view of a board 1000 having a top cap coat 1001 and a lower cap coat 1002 . A male side of the board 1014 includes an upwardly projecting bump 1016 and a lower pivot bump 1017 . A female side 1020 of the board includes a projecting bump 1022 that can snap over and interlock with the projecting bump 1016 , a flexible tap 1032 , which can help hold the boards together in alignment, and accommodate for expansion of the boards, and a water drain channel 1024 . Further, the female end has an open area to the inside of the flexible tab 1032 which can be sized and dimensioned to receive a heating wire or cable. FIG. 10A shows the heating element 1070 as having a generally vertical rectangular cross-section. [0109] FIG. 10B shows two of the boards 1000 interlocked adjacent to each other. In this embodiment, the aperture on the female end is shaped more vertically, so that the heating element can be oriented more vertically. [0110] FIG. 11A is a cross-sectional view of a board 1100 having a top cap coat 1101 and a lower cap coat 1102 . A male side of the board 1114 includes an upwardly projecting bump 1116 and a lower pivot bump 1117 . A female side 1120 of the board includes a projecting bump 1122 that can snap over and interlock with the projecting bump 1116 , a flexible tab 1132 , which can help hold the boards together in alignment, and accommodate for expansion of the boards, and a water drain channel 1124 . Further, the female end has an open area to the inside of the flexible tab 1132 which can be sized and dimensioned to receive a heating wire or cable. FIG. 11A shows the heating element 1170 as having a generally vertical rectangular cross-section. [0111] FIG. 11B shows two of the boards 1100 interlocked adjacent to each other. [0112] The female sided of the boards of FIGS. 8A through 11D form a partially enclosed conduit for holding the heating element 870 , 970 , 1070 , 1170 , etc. When the boards are installed adjacent each other the male sides in some embodiments will substantially enclose the female-side conduit so the heating element is not exposed to water. [0113] FIGS. 12A-12D show the cross-sectional and other views of a dock board 1200 . [0114] Referring now to FIGS. 13A-13D , there is shown a decking board system 1312 including plural decking boards, in interlocking position. As shown in FIGS. 13A and 13B , the decking board 1300 generally includes a top cap coat 1301 and lower cap coat 1302 , as similarly disclosed in previous embodiments. As further shown, the decking board 1300 includes a male side or first longitudinal side 1306 of the decking board, a female side or second longitudinal side 1308 , and a main body 1304 intermediate to the male side 1306 and second side 1308 . [0115] In the decking system 1312 , the decking boards 1300 are configured for interlocking engagement with each other. As shown, the male side 1306 of the decking board 1300 is configured for cooperative interlocking engagement with the female side 1308 of an associated decking board 1300 . To facilitate this engagement, the male side 1306 generally includes an extension member 1314 , which extends generally laterally outward from the male side 1306 . The extension member 1314 is configured for insertion into the female side 1308 of an associated decking board 1300 in the system 1312 . [0116] The extension member 1314 generally includes a first surface 1326 and an opposing second surface 1336 defining a notch 1337 . As shown, the extension member 1314 further includes a generally upwardly projecting first lip 1316 positioned, proximate to the first surface 1326 . The extension member 1314 further defines an opening 1338 configured to receive a tongue 1320 from an associated decking board 1300 therein. The configuration of the male side 1306 in combination with the extension member 1314 provides a u-shaped configuration 1340 . [0117] The female side 1308 of the decking board 1300 generally includes a first portion or tongue 1320 and a second portion 1321 including a second lip 1322 or bump. The first portion 1320 and second portion 1321 have an opening formed therebetween defining a cavity 1362 configured to receive an extension member 1314 of a male side therein. [0118] As shown in FIG. 13B , the second lip 1322 extends in a generally downward direction from the second portion 1321 and is configured for snapping and/or interlocking engagement with a first lip 1316 provided by an associated decking board 1300 . The second portion 1321 further includes a second flexible member 1324 , positioned generally adjacent to the second lip 1322 , along the inner surface 1330 of the second portion 1321 . [0119] The second flexible member 1324 extends in a generally downward direction from the inner surface 1330 such that when the decking board 1300 is in locking engagement with an associated decking board, the second flexible member 1324 engages the surface 1326 of the extension member 1314 . The second flexible member 1324 has at least one prong extending generally downward. As shown in FIG. 13C , the second flexible member 1324 may have a two-prong configuration for engagement with the extension member 1314 . The first prong 1333 of the second flexible member 1324 may form a second seal, and the second prong 1331 of the second flexible member 1324 may form a third seal. Notably it is contemplated that the second flexible member 1324 can include more than two prongs 1331 , 1333 , without departing from the scope of the present invention. It is further contemplated that multiple second flexible members 1324 can be provided on the inner surface 1330 to provide additional seals with the extension member 1314 , without departing from the scope of the present invention. [0120] The tongue 1320 extends generally laterally outward from the female side 1308 . As shown, the tongue 1320 has a generally sloped inner surface 1332 . The female side 1308 of the decking board further includes at least one first flexible member 1328 , which extends from the surface 1332 in a generally upward direction. As such, the first flexible member 1328 is configured for engagement with an extension member 1314 of an associated decking board 1300 Notably it is contemplated that the first flexible member 1328 can include multiple prongs or members to provide multiple points of engagement with the extension member 1314 . Further it is noted that one or more first flexible members 1328 can be provided on the tongue 1320 to provide multiple seals with the extension member 1314 to further block moisture. [0121] FIGS. 13A and 13D shows a decking board system 1312 including a first decking board 1300 a and a second decking 1300 b, configured to be interlocked adjacent to each other. As shown, the extension member 1314 a of decking board 1300 a is inserted into cavity 1362 b of the decking board 1300 b. The second flexible member 1324 b and first flexible member 1328 b cooperatively engage the extension member 1314 a. As such, the second flexible member 1324 b engages the surface 1326 a of the extension member 1314 a forming a seal, and the first flexible member 1328 b engages the notch or recess 1337 a. The first lip 1316 a of the extension member 1314 a engages the inner surface 1330 b of the decking board 1300 b. The second lip 1322 b of the decking board 1300 b engages the inner surface 1326 a of the decking board 1300 a. Additionally, the tongue 1320 b is inserted below the surface 1338 a. [0122] As shown in FIG. 13C , the decking board 1300 provides an opening 1342 for receiving a fastening member or component, such as a bolt or screw. As such, the decking board 1300 may be secured to an adjacent surface. Additionally, FIG. 13C illustrates that when the decking boards are in engagement, channel 1340 is formed between the decking boards 1300 a, 1300 b to facilitate fluid removal from the decking board surfaces. [0123] Although the various embodiments have been described in detail, it should be understand that the invention that the invention is capable of other embodiments and its details are capable of modifications in various obvious respects. As is readily apparent to those skilled in the art, variations and modifications can be affected while remaining within the spirit and scope of the invention. Accordingly, the foregoing disclosure, description, and figures are for illustrative purposes only and do not in any way limit the invention, which is defined only by the claims.

A decking system is made up of a variety of decking boards and other components are disclosed. In some aspects, the decking boards are connectable to each other so that adjacent boards will provide a water barrier and a drainage channel. Some versions of the boards may have a hollow region to accept the provision of heating elements or other accessory structures. A connector piece is disclosed in various embodiments span the gap between the butt ends of the boards to provide a water barrier at the butt ends of the boards. A gutter and downspout system is disclosed, as well as structures for protecting the ends or sides of the deck structure.

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims priority to U.S. Provisional Application Ser. No. 60/494,974, filed Aug. 14, 2003, and incorporated herein by reference. BACKGROUND [0002] Individual investors seeking diversification and professional management of their investments have frequently chosen mutual funds as their preferred investment vehicle. Often a small or mid-tier investor would hold a small portfolio of individual securities for speculation or amusement, but would look to mutual funds for long-term growth. Only the wealthiest investors had sufficient assets to build well-diversified portfolios from individual securities or attract the attention of professional money managers. [0003] For many investors, managed accounts are a superior alternative to mutual funds. Two advantages they offer investors are direct ownership of securities and a tax regime in which only the investor's own portfolio determines the investor's tax liability. However, managed accounts require a large investment that is prohibitive to all but the wealthiest investors. SUMMARY [0004] In one embodiment, customizable, index-based stock management methodology is provided. This methodology provides for diversification and risk control of indexing combined with individual customization and active tax management. A system employing the methodology permits individual investors to invoke investment processes that track indexes to gain specified market exposure, control risk, and minimize costs while invoking individual preferences, current holdings, or social concerns. [0005] Security selection and indexing systems and methods are provided to allow smaller investors to achieve similar performance of a target index in separately managed accounts. These systems and methods (“active indexing”) provide pre-tax performance similar to those of specific benchmark indexes with a subset of securities. Furthermore, active tax management strategies allow for greater post-tax returns. Active indexing provides similar returns to a target index and the tax management strategies only available to separately managed accounts but without the large investment required by traditional managed accounts. [0006] As an aid to understanding the disclosure herein, the Standard and Poor's 500 Index (S&P 500) is used as an exemplary index in a non-limiting context. Other indexes may be selected as a matter of design choice, such as an investor's preference. For example, an investor may select a health care index, over the S&P 500, in the belief that such an index would be more lucrative than a general market index. The S&P 500 has established categories (“sectors”) within the S&P 500 determined by the Global Industry Classification Standard (“GICS”). If another publicly available index or custom index is used, then a corresponding subdivision of the index into sectors may be made to further distinguish subsections comprising the index. When referring to the S&P 500 exemplary index, individual securities may be referred to as stocks. However, if another index is substituted for the S&P 500, individual securities may be bonds, commodities, futures contracts, or other financial instruments that comprises the selected index. [0007] In one embodiment, a security selection method is provided to achieve similar pre-tax performance of the target index with a subset of the constituent securities. The method may comprise selecting an index, determining the index's sector weights, selecting a target number of securities for the account, and purchasing the securities. [0008] An index is selected based on an investor's preference, existing portfolio, and/or other personal or strategic factors. For example, a belief that the general market is a lucrative investment may lead an investor to select the S&P 500. Next, the index's sector weights are determined. Weighting by market capitalization is one method of determining weights. Other weighting methods may be employed to target a particular segment of the market, for example, earnings ratio, yield, debt-to-equity, market share, or other attribute. Weighting of the index is reflected by the weighting of the sectors within the portfolio. For example, if the S&P 500 energy sector has a market capitalization of $200 billion and the health care segment has a market capitalization of $100 billion, the portfolio would be built with a corresponding capitalization having substantially twice the investment in the energy sector stocks as health care sector. Optionally, an adjustment may be employed to exclude securities or sectors based on, for example, an investors existing portfolio or investment strategy. Adjustment factors provide a custom index that may be created from a publicly available index and modified to suit the investor. As a benefit, an investor who views a particular industry segment as detrimental or lucrative to his portfolio may modify the index. As another benefit, investors that have an existing investment in a given sector may not wish to increase their exposure in that sector and the resulting index may then exclude the given sector. Individual securities may be excluded, as discussed below. Once the sectors and sector weights of an index have been determined, and optionally customized, individual securities are selected. [0009] In another embodiment, methods of selecting securities within a sector is provided. In the embodiment, securities are sorted by market capitalization, from largest to smallest. Categories of securities are then determined based on an investor's preference. [0010] In another embodiment, a division of securities within sector is determined by buckets. As a further embodiment, buckets are market capitalization tranches. [0011] In another embodiment, a target number of securities are selected reflective of an investor's objectives. The investor's preference may be governed by cost of trading large versus small blocks of securities, diversification preferences, or other personal or strategic objectives. [0012] In another embodiment, the number of securities to put into each sector is determined. The number of target securities is preferably larger than the number of sectors in the index. At least one security is put into each sector first, then the number of securities per sector is determined by: ROUND[(percentage of securities in sector)×(total number of securities desired−number of sectors)]+1. [0013] In another embodiment, an investor may wish to exclude a selected security. As an option the excluded security is omitted. As another option, the target index is customized to exclude the excluded security. As yet another option, a substitute security replaces the excluded security. And as yet another option, additional investment in other selected securities replaces the excluded security. [0014] In another embodiment, an exchange traded fund (“ETF”) is added to a portfolio with a number of securities below a threshold number, such as 50. As a benefit, adding an ETF to a small security-count portfolio may reduce its index tracking error. [0015] In another embodiment, the ETF comprises a reserve, such as 1% of the portfolio, to provide a ready source of liquidity to pay fees and to provide reserve for market fluctuations between the determination of a portfolio to acquire and the actual acquisition cost. [0016] In another embodiment, a percentage of the portfolio is cash, such as 1% to provide a ready source of liquidity to pay fees and to provide reserve for market fluctuations between the determination of a portfolio and the actual acquisition of the portfolio. [0017] As markets fluctuate, a need for rebalancing may arise to keep the portfolio aligned with the target index. In one embodiment, rebalancing is applied to a sector, category, or individual security. If a sector misweight is greater than a misweight threshold, such as 2%-absolute the sector is rebalanced. Using cash from tax-loss harvesting, disclosed below, replacement securities are then selected. The largest underweight sector is rebalanced first by purchasing constituent securities. If a sector is missing a security, the missing security is purchased first according to the initial allocation, disclosed above. For example, if the sector has 9 securities, it would then purchase security number 10 from the next category to be populated. If the sector is not missing any securities, additional shares of existing securities are purchased. Securities in the first category, such as the first tranche, may be purchased according to the initial portfolio setup, such as purchasing tranche 1 securities from largest to smallest and tranches 2, 3, or 4 securities from the next closest to the median. As an option, a replacement method may be selected which is dissimilar to the method used to populate the initial portfolio. [0018] In another embodiment, additional rebalancing occurs repeatedly as needed. Securities at or above the over-weighted threshold are sold and rebalanced but additional rebalancing may be required at the sector level, even though no individual security is overweight. Sector securities are sold to eliminate a sector over-weight. [0019] In another embodiment, tax-loss harvesting is provided. As a security declines in price, upward price potential may still be present. Simultaneously, the owner may wish to realize the lost value of the security for tax purposes. Current tax laws in countries such as the United States prohibit realizing a loss if the same security is purchased 30 days before or after the sale, known as the “Wash Sale Rule.” By repurchasing a similar security, e.g., purchasing Ford after selling General Motors, or purchasing McDonnell Douglas after selling Boeing, a sector's position is rebalanced back to the target index and a tax loss may be realized. [0020] In another embodiment, dividend income is invested in ETF until a threshold, for example 1.5% of the portfolio value, is held in the ETF. Once the ETF threshold is met, securities are purchased according to at least one methodology disclosed herein. [0021] In another embodiment, total portfolio liquidation is provided by selling all securities, ETF, and other non-cash holdings. As an option the account may be closed. In another embodiment, a partial reduction in holdings is executed; as an option, the owner of the account may receive a disbursement of the resulting funds. As a further option, the remaining portfolio is rebalanced. BRIEF DESCRIPTION OF ILLUSTRATED EMBODIMENTS [0022] FIG. 1 shows a stock selection and indexing system. [0023] FIG. 2 . shows one process embodiment for selecting and indexing stocks. [0024] FIG. 3 , FIG. 4 , FIG. 5A , FIG. 5B , FIG. 5C , FIG. 6 , FIG. 7A , FIG. 7B , FIG. 7C , FIG. 7D , FIG. 7E , FIG. 7F , FIG. 8A , FIG. 8B , FIG. 9A , FIG. 9B , FIG. 10A , FIG. 10B , FIG. 11A and FIG. 11B illustrate an embodiment of processes for selecting and manage securities. [0025] FIG. 12 illustrates tax savings obtained. [0026] FIG. 13 illustrates tracking differences. [0027] FIG. 14 illustrates distribution curves pre-tax. [0028] FIG. 15 illustrates benefits of stock selection and indexing according to the teachings herein. DESCRIPTION OF PREFERRED EMBODIMENTS [0029] FIG. 1 shows a stock selection and indexing system 10 that applies principles of stock indexing while providing customization and tax management capabilities. System 10 is shown in an exemplary architecture that includes a server 12 . Server 12 has stock selection and indexing software 14 , a processor 16 and a database 18 . A remote computer 20 may connect with server 12 through a network 22 (e.g., the Internet) such that a user at computer 20 may initiate and run software 14 . For example, processor 16 responds to requests from network 22 to initiate and run software 14 . Results from software 14 may be stored locally within database 18 or communicated over network 22 to computer 29 , for example. [0030] Server 12 may also connect with remote databases 24 that provide, for example, information (e.g., price) regarding traded securities on the stock exchange. Databases 24 may connect to server 12 through a network 26 (e.g., the Internet). [0031] Server 12 may also connect with a management computer 28 , through network 30 (e.g., a local area network), which may be used to update software 14 , for example. [0032] In an example of operation, system 10 provides selection and indexing of securities in response to user requests at computer 20 . Through separately managed accounts, each such user (investor or client) may utilize system 10 to manage direct ownership of securities, customizing stock portfolios to individual needs and preferences while managing taxes. As described in more detail below, tax-management strategies may be employed to shelter gains and harvest losses to increase after-tax returns. [0033] Indexing employed by system 10 may serve to maximize market exposure while minimizing portfolio risk, to match performance of a particular index by investing in all, or a subset of, securities within the targeted index. System 10 may therefore build portfolios that provide a pre-tax return similar to a selected benchmark that is consistent with requested customization and tax management. [0034] Through system 10 , stocks may be allocated and selected by a stratified sampling within a sector. The selected stocks may then be equally overweighted, thus avoiding overly-large active bets on one stock versus another. Loss harvesting and rebalancing may be performed at quarter end dates. If the portfolio holds a security that is deleted from the index, additional rebalancing may occur on that date. Both loss harvesting and rebalancing may be controlled by thresholds. [0035] FIG. 2 shows a process 100 for allocating and selecting securities. Process 100 is for example implemented by software 14 , FIG. 1 . Briefly, in step 101 , net assets are calculated. In step 102 , cash is reserved in a buffer. An example of step 102 is to reserve the cash for exchange traded funds (EFTs). In step 103 , non-indexed securities are sold. In step 104 , loss harvisting is performed. Step 104 is for example implemented when stock prices decline by X% or more; for example X is five (5).In step 105 , new stocks are determined for a portfolio. In step 106 , weightings (e.g., equal overweighting) and cash distributions are set in the portfolio. [0036] By implementing process 100 , a portfolio may continue to track an index despite the sale securities that were originally desired but which can no longer be purchased due to wash sale restrictions. Accordingly, through system 10 an initial portfolio may be constructed such that, if harvested, there would be suitable securities available to minimize tracking differences to the index. For example, an initial portfolio with the largest stocks may track the index reasonably well, but, upon harvesting, a porfolio is createed with smaller stocks. [0037] Additional exemplary detail of steps 101 - 106 are now described. In step 101 , Net Assets are the sum of the current market value of securities and cash in a portfolio. The cash component includes all dividends earned during the period (applies only to existing portfolios). For initial portfolios, the net assets may use a starting value of $100,000. [0038] In step 102 , accounts may hold reserve cash for fees (e.g., 1% of portfolio value) and/or for ETFs, for example. Using ETFs results in lower active risk (because ETFs nearly track an index perfectly) but will also result in lower tax alpha. Each percentage increase in ETFs reduces the standard deviation of tracking differences by the same percentage, but also reduces the tax alpha by a similar percentage. So, for example, if a portfolio without ETFs has a standard deviation (active risk) of 3.0% and an average tax alpha of 2.0%, holding ETFs at 10% of the portfolio reduces the active risk to about 2.7% and reduces the tax alpha to about 1.8%. System 10 and/or process 100 by therefore reserve cash for ETFs for any of the following three purposes: to create, by proxy, a tracking portfolio with substantially fewer stocks than the benchmark's 1500; to decrease tracking differences, for example by holding 10% of the portfolio in ETFs; and/or to manage cash. [0039] In step 103 , once cash and ETF balances are reserved, non-index securities are sold. This is customizable if, for example, a user requires only tax-free transitioning or restricts the sale of certain securities. If all non-index securities are sold as of the last day within the index, for example, closing prices and applied transaction costs of 35 basis points may be applied to represent the spread. [0040] In step 104 , securities that reach a desired loss harvesting threshold are sold. Harvesting is for example performed if sufficiently exceeding estimated costs of the trade. One exemplary threshold for harvesting occurs when the estimated tax benefit exceeded 175 basis points times the market value of the trade (this is approximately a price depreciation of 5%). The tax benefit may be estimated by multiplying the unrealized capital loss by the appropriate combined tax rate. The loss harvest threshold is met, in this example, when the tax rate x unrealized capital loss>1.75% times the market value. The tax rate may be determined per lot using long-term or short-term capital gains tax rates. If there are no securities in the portfolio (as in an initial portfolio), this step may be skipped. [0041] In step 105 , the Global Industry Classification Standard (GICS) may be used to divide the index into its ten (10) sectors. The portfolio stocks are allocated to each sector in roughly the same proportions. Mathematically, they may be adjusted to ensure that each sector has at least one stock and rounded to whole numbers as in the following algorithmic example: Initial number of stocks per sector=Round down (# stocks per sector index/# stocks in index)−(number of desired stocks in portfolio−number of sectors)+1. This algorithmic example typically results in fewer than the total desired number of stocks. The sectors may then be sorted by ascending initial number of stocks per sector and descending sector index market capitalization. One stock may be added per sector, from top to bottom, until the total number of stocks allocated reaches the total desired number; this yields the adjusted number of target stocks per sector in the portfolio, in this example. [0042] Continuing with step 105 , each sector in the index is then divided into tranches. In an exemplary embodiment, the number of tranches per sector is equal to the greater of four or the number of portfolio stocks allocated. (referred to herein as “Flex Min Bucketing”). Stocks may be sorted in descending weight within each sector, and then divided into tranches, where each tranche is split at 1 divided by the number of desired tranches. If for example five tranches are desired, the breakpoints are for every 20% in cumulative weight. Because the cumulative weight does not fall exactly on a breakpoint, only the cumulative weight less than the next breakpoint is included in the tranche. The stock where the cumulative weight is greater than the breakpoint falls into the next tranche. Hence, for example, instead of tranches at the 20%, 40%, 60%, 80%, and 100% cumulative weight marks, they may instead be at 18.8%, 38.3%, 59.6%, 78.5%, and 100% (in this example; all stocks that do not fit into the second to last tranche automatically fall into the last tranche). [0043] Continuing with step 105 , once a desired target number of stocks per sector and the associated tranches are known, stocks are selected. In selecting stocks, all stocks remaining in the portfolio after loss harvesting and selling non-index constituents are first added to the rebalanced portfolio. Each of these becomes the selected stock for their respective tranche. For example, if five stocks are desired and three remain in the portfolio after loss harvesting and selling non-index securities, they will be added to the new portfolio. If these stocks are in the first, third, and fifth tranches, additional securities will not be added into those tranches. Additional stocks may be added to the portfolio if stocks are missing from their target tranche, but extras may not be removed. In this case, a new stock would be added to the second and fourth tranches. [0044] If additional stocks are to be added, they may adhere to the following rules. In the first tranche, the largest stock is selected (but if there is already a stock in the tranche, no new stock need be selected, so the stock in the new portfolio may not be the largest stock. If the largest stock is restricted (due to wash sale rules or client restrictions, for example), then the next largest unrestricted stock is selected. If there are no other available candidates in the first tranche (e.g., it may have only one harvested stock, or it may have all restricted stocks), then the next largest stock is chosen, regardless of how far down it needs to search in subsequent tranches. For stocks initially targeted in tranches other than the first, the stock closest to the mean of the cumulative weight of the trance may be selected. If restricted, the next closest stock may be chosen. If no stock is available in its tranche, it may look to the closest to the mean stock in the next lower tranche. If no stock is available in the last tranche, then no stock may be chosen. [0045] Due to market movement and index reconstitution, portfolios may have multiple securities falling into the same tranche over time. For example, if five stocks are desired and three stocks remain in the portfolio, after loss-harvesting, it would appear that two more stocks would be purchased; however, more stocks may actually be purchased in this case depending on which trances the existing stocks are in. If two of the three remaining stocks are in the first trance and the third is in the third tranche, then the strategy may for example choose one new stock in each of the second, fourth, and fifth tranches, resulting in six total stocks in the new portfolio. If strict adherence to the total number of desired target stocks is maintained, more stocks may be sold (e.g., those that have shifted tranches from the prior rebalance), thereby increasing turnover and capital gains; alternatively, tranches in this case may be left unfilled, disrupting the portfolio's ability to track an index. As neither of these scenarios is desirable, the portfolio sizes may be allowed to float. [0046] In step 106 , weights the selected stocks. An incorrect weighting may cause substantial tracking differences to an index. For example, the S&P 500 and S&P Equal Weight Indexes have the same constituents, but substantial tracking error to one another. Accordingly, in step 106 , portfolios are weighted to be sector neutral. For example, if Financials are 23% of the index, then they will be 23% of the portfolio. The target weight for each stock within a sector may be equal to the stock's index weight within the sector, plus an overweight. By using only a subset of the index securities in the portfolio, some or all of the selected stocks may be overweighted. The overweight amount may be the same for all stocks and determined by the sum of the security weights within a sector for those securities not chosen to be in the portfolio; this figure is then divided by the number of target stocks in the sector. For example, the sum of the index weights of the chosen securities within a sector may be 80%, leaving 20% of the weight in the sector to be equally distributed among five stocks. Thus, each of the stocks, in this example, receives 20%/5=4% overweight. If a selected stock has an index weight of 18% of a sector, its weight in the portfolio will be 22%. Likewise, if a selected stock has an index weight of 1%, its weight in the portfolio will be 5%. [0047] A current stock may be restricted from purchasing due to wash sale rules (there may be multiple lots per stock, and only those lots that exceed threshold may be harvested), in which case no further shares may be purchased. The cash that would have been distributed to the stock may be redistributed. A priority may be to keep the cash in the same sector first and then redistribute the cash evenly amongst the other unrestricted stocks. If all stocks are restricted, then the cash may be redistributed across the other sectors. [0048] Since stocks in the portfolio may be misweighted versus their target, buy and sell tolerances may be used to avoid excessive rebalancing. While rebalancing maintains a well-constructed index-based portfolio and manages active risk, there is a tradeoff between tracking and transaction costs. Thus, securities that are overweighted by more than 1.5% versus their target may be sold down to their target weights. Likewise, small purchases for rebalancing may be limited if they increase turnover. When securities in gain positions are sold for rebalancing purposes, they may be sold by lot in order of minimizing taxes using respective long-term or short-term tax rates and applying them to losses before gains. [0049] It should be apparent to those skilled in the art that there are many alternatives to distributing where and how to overweight. Overweighting nonethless may provide several advantages over cap weighting or tranche weighting (e.g., setting the weight of each of 5 stocks to 20%). For example, cap weighting forces the largest absolute percentage overweight to the largest names, possibly reducing the weight of the smallest names to the point that they round to 0 or some other impractically small amount. Using tranche weighting on the other hand artificially increases the weight of the smallest names, essentially creating an equal weighted portfolios within sectors which would poorly track a cap weighted index. [0050] FIG. 3 , FIG. 4 , FIG. 5A , FIG. 5B , FIG. 5C , FIG. 6 , FIG. 7A , FIG. 7B , FIG. 7C , FIG. 7D , FIG. 7E , FIG. 7F , FIG. 8A , FIG. 8B , FIG. 9A , FIG. 9B , FIG. 10A , FIG. 10B , FIG. 11A and FIG. 11B illustrate another embodiment of processes suitable to select and manage securities; such processes are for example implemented by system 10 of FIG. 1 , such as through operations by software 14 . FIG. 3 shows a rebalancing process 1000 . FIG. 4 shows a harvesting process 1100 . FIG. 5A-5C shows a rebalancing process 1200 . FIG. 6 shows a lot harvesting process 1300 . FIG. 7A-7F show a stock selection process 1400 . FIG. 8A-8B show an invest remaining portfolio value process 1600 . FIG. 9A-9B show a loop content process 1700 . FIG. 10A-10B show a select representative constituents process 1800 . FIG. 11A-11B show a loop content two process 1900 . [heading-0051] BACKTEST EXAMPLE [0052] The following describes a backtest which confirms delivery of superior, after tax performance versus the S&P 500 by applying tax loss harvesting on an index-based account generated by system 10 and employing processes such as described in connection with FIG. 1-15 . While index funds tend to be tax efficient by their nature of low turnover, their after tax returns still tend to be less than their pre-tax returns. But using the above-descrived methodology (described in connection with FIG. 1 and 2 , for example) results in after tax returns that are greater than pre-tax returns. [0053] The benchmark results utilized portfolios with 50, 100, 150, 200, and 250 initial stocks, 1% cash holdings, and include estimated transaction costs of 35 basis points on all trades. They do not include additional wrap or management fees. [0054] This backtest used the S&P 500 as the benchmark. Portfolios were run beginning Dec. 31, 1994 through Dec. 31, 2002 with a new portfolio starting each month, yielding 96 portfolios and 3655 rolling twelve-month observations: The portfolio beginning Dec. 31, 1994 has 85 rolling twelve-month periods, beginning Jan 31, 1995 has 84 rolling twelve-month periods, and so on. Table 1 shows these results for any given twelve month period: TABLE 1 Rolling 12 Month periods (out of 3655 observations): 50 Base 50 Stocks 100 Stocks 150 Stocks 200 Stocks 250 Stocks Pre-Tax Average Tracking Difference 0.16% −0.81% −0.61% −0.17% 0.14% 0.47% Median Difference 0.13% −0.62% −0.45% −0.08% 0.20% 0.46% Standard Deviation 3.21% 3.54% 2.61% 2.16% 2.08% 2.07% Most Underperforming 12 Month Period −11.10% −15.61% −9.99% −7.63% −9.76% −9.56% Most Overperforming 12 Month Period 9.57% 10.28% 9.27% 11.28% 8.59% 9.62% Probability of Underperforming > 0.5% 42.05% 51.63% 49.03% 41.45% 34.97% 28.48% Probability of Underperforming > 3.5% 11.35% 19.53% 13.65% 6.43% 4.24% 3.01% Probability of Underperforming > 5.5% 4.46% 9.96% 3.72% 1.56% 1.01% 1.18% Post-Tax Average Tracking Difference −0.75% 2.11% 2.57% 2.99% 3.38% 3.70% Median Difference −0.65% 2.28% 2.44% 2.63% 2.87% 3.11% Standard Deviation 3.20% 4.03% 3.30% 3.13% 3.24% 3.35% Most Underperforming 12 Month Period −12.96% −14.17% −7.86% −4.13% −4.77% −6.74% Most Overperforming 12 Month Period 8.11% 15.14% 16.09% 20.06% 19.10% 20.18% Probability of Underperforming > 0.5% 52.37% 24.57% 17.26% 9.74% 6.68% 4.46% Probability of Underperforming > 3.5% 16.63% 8.15% 2.65% 0.25% 0.25% 0.19% Probability of Underperforming > 5.5% 6.89% 3.34% 0.33% 0.00% 0.00% 0.08% Tax Alpha Average Tax Alpha −0.91% 2.92% 3.18% 3.16% 3.24% 3.24% Median Tax Alpha −1.05% 2.48% 2.82% 2.59% 2.62% 2.60% Standard Deviation 1.14% 3.00% 2.67% 2.46% 2.34% 2.31% Worst Case Tax Alpha −5.28% −2.58% −1.84% −0.52% 0.29% 0.02% Best Case Tax Alpha 2.55% 16.31% 15.45% 15.99% 15.70% 14.81% Probabilityof Tax Alpha > 0.5% 12.28% 73.21% 84.51% 95.76% 98.91% 99.21% Tracking Statistics R-Squared 97.53% 97.09% 98.35% 98.87% 98.99% 99.05% Correlation 0.9876 0.9853 0.9917 0.9943 0.9949 0.9953 Beta 0.9966 1.0074 0.9922 0.9787 0.9698 0.9589 50 Base: 50 Stocks, No Loss Harvesting, No Transaction Costs, 1% Cash The other cases use loss harvesting, 35 bps transaction costs, 1% Cash [0055] The following observations and findings are determinable from the backtest: Excluding transaction costs and loss harvesting, a 50 stock portfolio tracks an index pre-tax with a standard deviation of 3.2%. Increasing the number of stocks in the portfolio results in smaller tracking differences (active risk) pre-tax. Tax alpha from loss harvesting varies substantially depending on the date of the initial investment and the subsequent market conditions. Pre-tax active risk for a 50 stock portfolio is about 3.5%; for 100 stocks portfolios it is about 2.6% and falls to about 2% at 200 stocks. Loss harvesting opportunities are greater in declining, volatile markets. Tax alpha in any twelve month period may range from about −2.6% to +16.3%, with an average of 2-3%. The probability of a tax alpha greater than 0.5% in any twelve month period is 73% for a 50 stocks, 85% for a 100 stocks, 96% for 150 stocks, and 99% for 200 and 250 stocks. In rising markets, tax alpha may be negative due to rebalancing the portfolio with positions in capital gains. There is a trade-off between minimizing tracking differences, maximizing tax alpha, and minimizing costs. The strategy provides upside market gains with downside post-tax protection. Adding ETFs to a portfolio proportionately reduces the active risk, but it also proportionately reduces the tax alpha. Pre-tax underperformance is expected due to including transaction costs and the assumption of holding 1% in cash. Roughly 25 basis points per year are attributable to transaction costs and another 15 basis points per year for cash drag. [0068] The “50 Base” portfolio of Table 1 shows that process 100 tracks an index closely using stratified sampling. This base case used 50 stocks with no transaction costs and no loss harvesting. Rebalancing was done quarterly for risk management purposes only. Such a portfolio track a pre-tax index with a standard deviation of 3.2% over the observed time period. The observed time period included extremely volatile markets up and down, yet the base case portfolio had an r-squared of 98%, correlation of 0.99, and a beta of nearly 1. As a point of reference, the 50 stock S&P 500 portfolio has a predicted tracking error of 2.6% using Barra as of Dec. 31, 2003. [0069] The backtest also illustrated tradeoffs between the otherwise conflicting goals of high correlation and maximizing tax alpha. Ideally, the “best” portfolio tracks the index with perfect correlation on a pre-tax basis, while maximizing loss harvesting, and, hence, maximized after-tax returns. However, harvesting losses require portfolio rebalancing, thereby incurring transaction costs and portfolio weighting to something less than ideal (if, for example, minimizing pre-tax tracking were the only concern). This in turn may lead to greater tracking variances. If priority is placed on minimizing tracking differences, it would require holding more stocks and forgo loss harvesting, thus reducing post-tax alpha. [0070] Parameters may therefore be selected to balance these opposing objectives; these parameters include, but are not limited to: sell tolerances, buy tolerances, loss harvesting thresholds, transaction costs, cash balances, ETF holding levels, initial number of stocks, and tax rates. [0071] Note that the backtest included transaction costs (spread) of 35 basis points for every trade, and assumed holdings of about 1% in cash to avoid overdrawing the accounts and to reserve for payments of fees. Further, the backtest used only a whole number of shares. The backtest was therefore realistic of actual transactions. [0072] In the backtest, portfolios of all sizes outperformed the index after tax if loss harvesting is used, yet they still tracked the index (pre-tax) with high r-squared and correlation figures and betas close to 1. [0073] Indexing by system 10 , FIG. 1 , and process 100 , FIG. 2 , thus follows the market on a pre-tax basis (less transaction costs and cash drag), yet outperforms on a post-tax basis by tax loss harvesting. Loss harvesting involves realizing capital losses by selling securities that have declined in value. These losses may be used to offset capital gains inside or outside the portfolio for tax purposes. The end result is tax savings up to for example 41% on the amount of the realized capital loss. That is, for every $10,000 in capital losses realized, a user of system 10 may save roughly $4100 in taxes. The money raised from loss harvesting is used to buy new securities, or additional shares of existing securities, to construct a new index-based portfolio while obeying wash sale rules and user-specific restrictions. [0074] Note that loss harvesting benefits do not eliminate taxes permanently, but rather defers the taxes into the future because proceeds generated from loss harvesting are reinvested into the portfolio, lowering the cost basis. Maximum benefit is realized if assets are passed on to an heir since they will receive a “step up” value in cost basis (i.e., the cost basis is reset to current market values, erasing unrealized capital gains). This is an enhanced version of a classic buy-and-hold strategy, which has a tangible tax benefit by deferring the realization of capital gains for as long as possible. But unlike a standard buy-and-hold strategy, loss harvesting actively realizes losses. [0075] The backtest used data from Compustat's Expressfeed from S&P; but this data is somewhat different than the published index data. The main differences are in the shares outstanding and treatment of corporate actions. Expressfeed updates shares outstanding as they obtain the information. However, the S&P indexes only make immediate changes in shares outstanding when they are greater than 5%, to avoid excessive turnover from a practitioner's point of view. This timing difference creates artificial tracking errors in the backtest. With regard to corporate action, when an index constituent (e.g., Palm) spins off part of its company, a real shareholder will receive value (usually in the form of shares) for the new company (e.g., PalmSource). In Expressfeed data, the share price of the parent security falls by the value of the spinoff, but the value of the new security is not accounted for, making the portfolio appear to lose value. To adjust for this in the backtest, such spinoffs were treated as a dividend to the parent company. Not all such situations could be accounted for, however; for that reason, calculated indices trend slightly negative over time. [0076] A shadow portfolio is a fully-replicating index portfolio, consisting of all stocks in the benchmark in their respective weights (essentially an index fund). All index additions and deletions were accounted for on the effective date of their changes. In the following description, shadow portfolios were allowed to hold fractional shares in order to avoid misweights due to rounding. All dividends and splits were captured and accounted for. [0077] There are two main reasons in creating and using shadow portfolios as a benchmark. First, they are used to most accurately calculate an after-tax benchmark (no indexes currently report their performance figures after-tax), and, second, to have the capability to provide custom pre- and post-tax benchmark returns. For example, S&P does not construct an S&P 500 Ex-Technology or S&P 500 Ex-Tobacco index. When such a portfolio is needed, system 100 may manage and benchmark the portfolio. [0078] For the most part, the shadow portfolios tracked the index total returns within 50 basis points due to a few small differences in data. As explained earlier, the main differences are the timing of shares outstanding updates and the treatment of spinoffs. Shadow benchmarking was used instead of the published index because it is most consistent with the data available for the backtest. Additionally, the shadow provides the most accurate representation of a benchmark for calculating post-tax comparable performance and subsequent tax alpha. While the shadow portfolios did not perfectly match the published index returns due to the limitations of the data, the backtested strategies were calculated based on the same data. Thus, the results of the backtest must only be compared to the performance of the shadow portfolios, not the published index. [0079] During the backtest, on a pre-tax basis, portfolios were measured monthly for beginning to ending market value to calculate pre-tax returns. Transaction costs of 35 basis points were applied to all trades. On a post-tax basis, portfolio performance was calculated as the difference between the current period's after tax value and the prior end of month's pre-tax market value. The current month's after tax value was calculated by subtracting the estimated taxes from the current pre-tax value. A federal tax rate of 35% was applied to short-term capital gains. The tax rate used for dividends and long-term capital gains was 15%. Calculations also included a California tax rate of 9.3%. Combined effective tax rates were applied using the federal rate×Calif. state tax rate (1- federal tax rate) to account for the state tax deductibility for federal taxes. If there were net losses realized, this would result in negative taxes (tax savings) and higher after-tax performance. Net gains result in tax costs and lower after-tax performance. All tax benefits are applied to the portfolios in the month in which they occurred. This convention is consistent with AIMR after-tax reporting guidelines. [0080] For purposes of the backtest, “tax alpha” (see Table 1) is defined as the difference between the post-tax tracking error and the pre-tax tracking error and may be positive or negative. Tax alpha in this definition is thus the net benefit (or cost, if negative) to the portfolio due to taxes. Pre-tax tracking error is the difference between the pre-tax performance of the portfolio and the shadow portfolio (the index as calculated). Post-tax tracking error is the difference between the post-tax performance of the portfolio and the shadow portfolio (the after-tax index, as calculated). The shadow portfolio used the same rules for applying taxes to realized capital gains/losses and dividends. Note that the shadow portfolio does not loss harvest and is representative of a full replication index fund. [0081] In the backtest, simulated backtests were run beginning Dec. 31, 1994 (as far back as GICS codes have history) through Dec. 31, 2002. A new portfolio started at the end of each month for a total of 96 portfolios (8 years×12 portfolios/year). Simulations were run for 50, 100, 150, 200, and 250 stock initial portfolios. Returns and performance figures were measured for the composite and for the individual portfolios. Tracking differences were measured before and after tax versus the calculated index (shadow portfolio). Portfolios were loss harvested and rebalanced at calendar quarters (and when a holding was deleted from the index), use transaction costs of 35 bps per trade, have minimum purchases of $100 per trade, will sell securities with more than 1.5% in overweight, and target 1% in cash. [0082] Measuring composite performance helps determine what the total performance is for all assets under management. Using the composite demonstrates how well short-term and long-term portfolios perform in up and down markets. [0083] The backtest results suggest that the composite tracks the index well on a pre-tax basis. Portfolios of all sizes have high r-squares and correlation, with betas close to 1. The composites outperformed on a post-tax basis over time, though there are a few cases in single years where the composites underperformed their after-tax benchmark; these are because the tax alpha generated was not sufficient to make up for any pre-tax underperformance. The backtest composites had positive tax alpha every year for all portfolio sizes over the duration of this backtest. [0084] Since portfolio performances in a composite offset one another, the standard deviations and range of the outliers tend to be smoothed over. Thus, the backtest considered the data two additional ways: 1) 8 full calendar year portfolios (i.e., Dec. 31, 1994-Dec. 31, 2002, Dec. 31, 1995-Dec. 31, 2002, etc.) to see how an investor would have performed if he had an initial investment at year-end, and 2) 96 individual portfolios analyzed in 3655 rolling twelve-month time periods. For full calendar years, the average portfolio has positive after-tax differences. The tax alpha generated for these portfolios more than made up for any pre-tax losses. In down markets, the outperformance post-tax tends to grow larger by actively loss harvesting. These results may be illustrated such as in FIG. 12 . [0085] As mentioned above, loss harvesting is highly dependent upon the start date of the portfolio. The full-year simulations were run with start dates of December 31 of each year rolling forward for full years though Dec. 31, 2002. Note that for a portfolio starting Dec. 31, 1994 the tax alpha is actually negative. This is due to rebalancing the portfolio (for risk management purposes) while it is predominantly has capital gain positions due to large advances in the market. Tax alpha becomes positive in later years when the market if falling. The tax alpha in those years is less than if a portfolio were to begin in a down market because the cost basis for the Dec. 31, 1994 portfolio is lower, so the market needs to fall further before the equivalent amount of tax alpha can be generated. [0086] Because the tax loss harvest benefit is highly dependent on the inception date (and thus cost basis) of the portfolio, simulations of the backtest were also run with a new portfolio starting every monthend beginning Dec. 31, 1994 and running through Dec. 31, 2002. Using this data, performance that any individual investor might see over 12, 24, and 36 month periods was evaluated. For the time period of the data, there were 85 portfolios with 12 months or more of data, yielding 3655 data points. The portfolio beginning Dec. 31, 1994 had 85 rolling 12-month periods; the portfolio beginning Jan. 31, 1995 had 84 rolling 12-month periods and so on. There were 2701 data points with 24-month rolling periods and 1891 data points with 36-month rolling periods. [0087] In the benchtest, it was shown that although a pre-tax portfolio may not track the pre-tax index perfectly in any given year, it will get closer on an annualized basis over time. Likewise, increasing the number of stocks in a portfolio decreases the active risk. See FIG. 13 . Also, holding fewer stocks achieves the same distribution as a portfolio with more stocks if you hold it for a longer period of time. See FIG. 14 . For example, the distribution curve for 50 stocks annualized over 36-month periods is very similar to that of 100 stocks annualized over 24-month periods or 150 stocks over 12-month periods. What this means is that you will eventually end up in about the same place, regardless of size, but you'll need to hold your portfolio longer with a fewer number of stocks. The longer your time horizon, the less size matters pre-tax. [0088] The benefit of loss harvesting rises when going from 50 to 150 stocks, but then tends to flatten out, due to having suitable stocks to reinvest in after harvesting. If the portfolio gets too large, it may result in “lockup,” where there are no other stocks to buy without violating wash sale rules. See FIG. 15 . [0089] The following statistical definitions were used with the benchtest: Beta: The measure of systematic risk of a security. Beta (or beta coefficient) is a means of measuring the volatility of a security or portfolio of securities in comparison with the market as a whole. Beta is calculated using regression analysis. A beta of 1 indicates that the portfolio's change in value will move with the market. A beta greater than 1 indicates that the portfolio's change in value will be more volatile than the market. A beta less than 1 means that it will be less volatile than the market. Correlation: A measure that determines the degree to which two variable's movements are associated. The correlation coefficient is calculated as: ρ xy = Cov ⁡ ( r x , r y ) σ x ⁢ σ y The correlation coefficient will vary from −1.0 to 1.0. −1.0 indicates perfect negative correlation, and 1.0 indicates perfect positive correlation. Standard Deviation: A measure of the dispersion of a set of data from its mean. The more spread apart the data is, the higher the deviation. In finance, standard deviation is applied to the annual rate of return of an investment to measure the investment's volatility (risk).One standard deviation away from the average accounts for somewhere around 68 percent of the annual returns in the time period. Two standard deviations away from the mean account for roughly 95 percent of the annual returns. And three standard deviations account for about 99 percent of the annual returns. R-Squared: A statistical measure that represents the percentage of a portfolio's movements that are explained by movements in a benchmark index. R-squared values range from 0 to 1. A higher R-squared value will indicate a more useful beta figure. A low R-squared means you should ignore the beta.

A system, method and software product describe a customizable, index-based stock management methodology. This methodology provides for diversification and risk control of indexing combined with individual customization and active tax management. The system employing the methodology permits individual investors to invoke investment processes that track indexes to gain specified market exposure, control risk, and minimize costs while invoking individual preferences, current holdings, or social concerns

BACKGROUND OF THE INVENTION The present invention relates to a transistor circuit employing insulated gate field effect transistors, and more particularly to a voltage-current converter circuit. Insulated gate field effect transistors (hereinafter abbreviated as IGFET's) have been widely used. Among their principal application, there exists a current source for supplying or absorbing a predetermined value of current. Such current sources are utilized, for example, as a constant current source for a differential amplifier or a current source for effecting charge or discharge of a time constant circuit. In accordance with improvements in circuit techniques in recent years, a capability of controlling a current value has been desired for a current source. In addition, due to the fact that power supply voltages have become low-voltage, stabilization of an operation at a low voltage and operations over a wide voltage range have been required. As is well-known, a source-drain current of an IGFET would not vary linearly as a fuction of a gate-source voltage. More particularly, representing a gate-source voltage by V GS , a drain-source current by I DS , a threshold voltage by V T and a current amplification factor by β, when the drain-source voltage V DS fulfils the condition of V DS >V GS -V T , the following relation is established: I.sub.DS =β(V.sub.GS -V.sub.T).sup.2 ( 1) and therefore, the drain-source current I DS has a square (the second powered) characteristic with respect to the gate-source voltage V GS . In various applications, this becomes great obstruction in the case where an IGFET is used in a linear circuit for which a linear relation beween a voltage and a current is required. However, even with IGFET's having such a characteristic, it is possible to contrive to obtain a linear relation between a voltage and a current. Now it is assumed that two IGFET's having respective threshold voltages V T1 and V T2 and an identical current amplification factor β are prepared and a common voltage V GS is applied between their gates and sources. Then, the respective drain-source currents I DS1 and I DS2 are represented by the following equations, similarly to Equation-(1) above: I.sub.DS1 =β(V.sub.GS =V.sub.T1).sup.2 ( 2) I.sub.DS2 =β(V.sub.GS -V.sub.T2).sup.2 ( 3) At this moment, the respective drain-source voltages V DS1 and V DS2 fulfil the relations of V GS1 >V GS -V T1 and V DS2 >V GS -V T2 . Considering now the difference between these currents flowing through the respective IGFET's, from Equations-(2) and -(3) above it can be seen that the following relation is established. I.sub.DS1 -I.sub.DS2 =2βV.sub.GS (V.sub.T2 -V.sub.T1)+V.sub.T1.sup.2 -V.sub.T2.sup.2 ( 4) In other words, the difference current between the drain-source currents of the two IGFET's has a linear relationship to the common gate-source voltage V GS . Accordingly, if provision is made such that when the same gate-source voltage is applied to two IGFET's having different threshold voltages and the same current amplification factor, the difference current between the drain-source currents of the respective IGFET's can be detected. Thus, even in a circuit constructed of IGFET's it is possible to realize a linear voltage-current characteristic. Although a sum of currents flowing through two IGFET's, respectively, can be obtained simply by connecting the IGFET's in parallel, a simple method for obtaining a difference between two currents has not been known. SUMMARY OF THE INVENTION It is one object of the present invention to provide a current source circuit which can output a current having a controllable current value. Another object of the present invention is to provide a linear voltage-current converter circuit. Still another object of the present invention is to provide a current source circuit having a wide range of operation voltage. Yet another object of the present invention is to provide a circuit in which a difference current between currents flowing through two IGFET's can be obtained in a relatively simple manner. According to one feature of the present invention, there is provided a linear voltage-current converter circuit comprising a first load element having one end connected to a first voltage source; a first IGFET having a drain electrode connected to the other end of said first load element, a source electrode connected to a second voltage source and a gate electrode connected to a first input terminal; a second load element having one end connected to said first voltage source; a second IGFET having a drain electrode connected to the other end of said second load element, a source electrode connected to said second voltage source and a gate electrode connected to a second input terminal; a third IGFET having a drain electrode connected to the drain electrode of said second IGFET and a source electrode connected to the source electrode of said second IGFET; a fourth IGFET having a drain electrode connected to an output terminal, a gate electrode connected to the gate electrode of said third IGFET and a source electrode connected to said second voltage source, and a differential amplifier having an inverted input terminal connected to the junction between said first load element and the drain electrode of said first IGFET, an uninverted input terminal connected to the junction between said second load element and the drain electrode of said second IGFET and an output terminal connected to the gate electrode of said third IGFET and the gate electrode of said fourth IGFET; said first and second input terminals being supplied with input voltages such that when said third IGFET is removed, the current flowing through said first load element may become larger than the current flowing through said second load element. According to another feature of the present invention, there is provided a differential amplifier comprising a first IGFET having a drain electrode connected to a first voltage source, a gate electrode connected to a control terminal and a source electrode connected to a first output terminal; a second IGFET having a drain electrode connected to said first voltage source, a gate electrode connected to said control terminal and a source electrode connected to a second output terminal; a third IGFET having a drain electrode connected to said first output terminal, a gate electrode connected to a first input terminal and a source electrode connected to a second voltage source; a fourth IGFET having a drain connected to said second output terminal, a gate electrode connected to a second input terminal and a source electrode connected to said second voltage source; and means for inversely amplifying a sum of a voltage variation on said first output terminal and a voltage variation on said second output terminal and applying the amplified signal to said control terminal. In the linear voltage-current converter circuit according to the present invention, a current proportional to an input voltage can be obtained over a wide range of input voltage. By employing such a linear voltage-current converter circuit as a current source for charging or discharging a capacitor in a time constant circuitry of an oscillator, it is possible to realize a variable frequency oscillator. The linear voltage-current converter circuit according to the present invention can be also utilized effectively in an analog-digital converter for converting an analog input voltage to an analog input current proportional to the input voltage, or on the contrary, in a digital-analog converter for converting an analog output voltage to an analog output current proportional to the output voltage. BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other features and objects of the present invention will become more apparent with reference to the following description of preferred embodiments of the invention taken in conjunction with the accompanying drawings, wherein: FIG. 1 is a circuit diagram showing one preferred embodiment of the present invention, FIG. 2 is a circuit diagram showing another preferred embodiment of the present invention, FIG. 3 is a diagram showing an input-output characteristic of the preferred embodiment shown in FIG. 2, FIG. 4 is a circuit diagram showing one example of an amplifier employed in the preferred embodiment illustrated in FIG. 1 or 2. FIG. 5 is a circuit diagram showing still another preferred embodiment of the present invention, FIG. 6 is a circuit diagram showing yet another preferred embodiment of the present invention, FIG. 7 is a circuit diagram illustrating one practical example of the preferred embodiment shown in FIG. 6, FIG. 8 is a circuit diagram showing a first example of an application of the present invention, FIG. 9 is a diagram showing an input-output characteristic of a Schmitt trigger circuit in FIG. 8, FIG. 10 is a circuit diagram showing a second example of application of the present invention, FIG. 11 is a circuit diagram illustrating one practical example of an oscillator circuit in FIG. 10. FIG. 12 is a circuit diagram showing a differential amplifier circuit in the prior art, FIG. 13 is a circuit diagram showing a differential amplifier circuit according to the present invention, and FIG. 14 is a circuit diagram illustrating one practical example of the differential amplifier circuit in FIG. 13. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now one preferred embodiment of the present invention will be described with reference to FIG. 1. While the description will be made, assuming that the IGFET's used in the preferred embodiment are N-channel type MOSFET's for convenience of explanation, the present invention should not be limited to such type of IGFET's, but the invention could be practiced basically in the same manner even with P-channel type MOSFET's. In the preferred embodiment shown in FIG. 1, while depletion type MOSFET's Q 5 and Q 6 having their respective gate electrode and source electrode connected together are used as first and second load elements, respectively, the present invention should not be limited to the use of such load elements. The voltage-current characteristics of the first load element Q 5 and the second load element Q 6 are selected to be identical. A first MOSFET Q 1 and a second MOSFET Q 2 have their gate electrodes connected to input terminals 8 and 9, respectively. The characteristics of the first MOSFET Q 1 and the second MOSFET Q 2 are selected such that under the condition where a third MOSFET Q 3 is removed, in the input voltage range for which this circuit must operate, the current flowing from a first voltage source 14 through the MOSFET's Q 5 and Q 1 to ground which forms a second voltage source may become larger than the current flowing from the first voltage source 14 through the MOSFET's Q 6 and Q 2 to ground. This means that under the above-mentioned condition the voltage V 11 at a point 11 is lower than the voltage V 12 at a point 12. A differential amplifier 7 should preferably have a gain of infinity in the ideal case, and it is connected in such polarity that when the voltage V.sub. 11 is lower than the voltage V 12 , the voltage at a point 13 is made more positive. When the voltage V 11 at the point 11 is lower than voltage V 12 at the point 12, the voltage difference is amplified by the differential amplifier 7 to make the voltage at the point 13 more positive, resulting in increase of the drain-source current of the MOSFET Q 3 , and thereby the voltage V 12 is lowered. On the contrary, when the voltage V 11 is higher than the voltage V 12 , the voltage V 13 is lowered, so that the drain-source current of the MOSFET Q 3 decreases, and thereby the voltage V 12 is raised. In this way, the voltages V 11 and V 12 are equalized by negative feedback. Since the current-voltage characteristics of the load elements Q 5 and Q 6 are identical, under the condition where the voltages V 11 and V 12 are equal to each other, the values of the currents flowing through the respective load elements are equal to each other. Accordingly, if the currents flowing through the drain-source paths of the MOSFET's Q 1 , Q 2 and Q 3 are represented by I 1 , I 2 and I 3 , respectively, the relation of: I.sub.1 =I.sub.2 +I.sub.3 is established, and consequently, the current I 3 becomes equal to the difference between the currents I 1 and I 2 . Since the threshold values of the MOSFET Q 3 and a fourth MOSFET Q 4 are identical, so long as the voltages V 12 , V 13 and V 10 at the points 12, 13 and 10, respectively, fulfil the relations of V 12 >V 13 -V T and V 10 >V 13 -V T , where V T represents the threshold values of the MOSFET Q 3 and MOSFET Q 4 , the current flowing through the drain-source path of the MOSFET Q 3 and the current flowing through the drain-source path of the MOSFET Q 4 are proportional to each other. In other words, in the illustrated circuit, an output current proportional to a difference between the drain-source current of the MOSFET Q 1 and the drain-source current of the MOSFET Q 2 can be derived from the output terminal 10. Furthermore, if the current amplification factors of the MOSFET's Q 3 and Q 4 are adjusted to be equal to each other, then it is also possible to obtain an output current equal to the difference current. Although the ground was used as the second voltage source in the above-described embodiment, the second voltage source should not be limited to such voltage source. Now another preferred embodiment of the present invention will be described with reference to FIG. 2. In this embodiment, enhancement type MOSFET's Q 5 ' and Q 6 ' having their gates and drains connected in common to a voltage source V DD are used as load elements, and an input voltage V in is applied to input terminals 8 and 9 in common. In FIG. 2, it is assumed that the voltage of the first voltage source (V DD ) is 10V and the second voltage source is the ground. It is also assumed that all the MOSFET's are of N-channel type, a threshold voltage V T1 of a MOSFET Q 1 is 0.5 V and threshold voltages of MOSFET's Q 2 , Q 3 , Q 4 , Q 5 ' and Q 6 ' are 1.0 V. Current amplification factors β of the MOSFET's Q 1 and Q 2 are selected to be equal to each other. To this end, in the case where mobilities of electrons in the channels of the respective MOSFET's are equal to each other, it is only necessary to select channel width W and channel length L, respectively, to be equal to each other. However, in the case where the threshold voltages V T of the respective MOSFET's are made different by a known technique of ion implantation into the respective channel regions then the electron mobilities are also different between the respective MOSFET's, and hence, their respective W/L ratios are made different by the corresponding amount. The value of the ratio of mobilities is typically 70-100%, and by way of example, assuming that the electron mobility in the MOSFET Q 1 is equal to 90% of the electron mobility in the MOSFET Q 2 , then it is only necessary to select the channel width W of the MOSFET Q 2 to be 0.9 times as small as the channel width W of the MOSFET Q 1 . By way of example, the current amplification factors β of the MOSFET's Q 5 ' and Q 6 ' are selected to be equal to 1/2 of that of the MOSFET Q 2 . To that end, it is only necessary, for example, to design the channel widths W of the MOSFET's Q 5 ' and Q 6 ' to be 0.5 times as small as the channel width W of the MOSFET Q 2 and to design the channel length L of the MOSFET's Q 5 ' and Q 6 ' to that of be equal to that of the MOSFET Q 2 . The current amplification factors β of the MOSFET's Q 3 and Q 4 could be selected arbitrarily, and by way of example, they could be selected to both be equal to the current amplification factor β of the MOSFET Q 2 . To that end, it is only necessary to design the channel widths W and channel lengths L of the MOSFET's Q 3 and Q 4 to be equal to those of the MOSFET Q 2 . The relation between the input voltage V in and the output current I out in the above-described circuit arrangement is illustrated in FIG. 3. It is to be noted that the output current I out is represented as normalized with respect to the current amplification factor β, of the MOSFET Q 1 . In FIG. 3 is also indicated a current I, flowing through the MOSFET Q 1 . As seen from FIG. 3, while the current I 1 flowing through the MOSFET Q 1 has a large non-linearity, the current I out derived at the output is linear in the input voltage range of 1 V to V 1 , which is equal to about 4 V. In this circuit arrangement, the lower limit of the input voltage V in is the voltage which makes the MOSFET Q 2 cut off, that is, the threshold voltage V T2 , which is equal to 1.0 V in the assumed case. On the other hand, the upper limit of the input voltage V in is the input voltage V in1 at the moment when the voltage V 11 at the point 11 becomes lower than V in -V T1 and hence the MOSFET Q 1 goes out of the saturated region, and accordingly, the threshold voltage V T (Q.sbsb.5 ' ) must satisfy the relation of V in1 >V T (Q.sbsb.5 ' ). This is always possible by increasing the current amplification factor β of the MOSFET Q 5 ' to a necessary extent. Therefore, under the ideal condition that the MOSFET's Q 1 and Q 2 have perfect square characteristics, the current amplification factors β of the MOSFET's Q 1 and Q 2 are perfectly identical to each other and the gain A of the differential amplifier is infinite, a perfectly linear output current can be obtained with respect to an input voltage V in which falls in the range of V T2 <V in <V in1 . In practice, however, such an ideal condition is impossible to be realized. Hence, a certain deviation from the perfectly linear relationship is necessary. Among the above-described requirements, it is not so difficult in such an integrated circuit to make the characteristics of the MOSFET's Q 5 ' and Q 6 ' coincide with each other to a practically unobjectionable extent because the configurations of the MOSFET's Q 5 ' and Q 6 ' could be made identical. In addition, with respect to the deviation of the characteristics of the MOSFET's Q 1 and Q 2 from the square characteristics, also their characteristics can be approximated to the square characteristics to a practically unobjectionable extent by elongating the channel lengths to a certain extent. In view of the above-mentioned facts, the remaining two requirements serve as factors of principally limiting the linear characteristics. With regard to the current amplification factors β of the MOSFET's Q 1 and Q 2 , while they can be closely approximated by designing the configurations of the respective MOSFET's to be identical, in the case where more precise coincidence is desired to be realized, it can be realized by preliminarily seeking for a difference in electron mobilities due to a difference in the amount of ion implantation and determining configuration ratios while taking this difference into account. With regard to the requirement for the gain of the differential amplfier, representing the gain of the amplifier by A and the ratios of channel width/channel length of the MOSFET's Q 3 and Q 6 by S 3 and S 6 , respectively, the following equation is fulfilled: ##EQU1## Since the relation of (S 2 /S 6 )>2 is normally satisfied, it can be seen from the equation that a good linearity having a current deviation ratio of 1% is obtained with a gain A of about 50. A differential amplifier having a gain or a degree of amplification of about 50 can be realized by a simple circuit as illustrated in FIG. 4. In this figure, a gate electrode of a MOSFET Q 11 serves as an uninverted input terminal, while a gate electrode of MOSFET Q 12 serves as an inverted input terminal, and a point 13 serves as an output terminal. Only MOSFET's Q 13 and Q 14 are depletion type MOSFET's, and the other MOSFET's Q 11 , Q 12 , Q 15 , Q 16 and Q 17 are enhancement type MOSFET's. The MOSFET's Q 15 and Q 17 are applied with a bias voltage V 13 at their gates to serve as current sources. Now additional preferred embodiments of the present invention will be described with reference to FIGS. 5 and 6. In the preferred embodiment illustrated in FIG. 5, load elements 51 and 52 have constructions similar to the MOSFET's Q 5 and Q 6 in FIG. 1 or similar to the MOSFET's Q 5 ' and Q 6 ' in FIG. 2. MOSFET's Q 51 , Q 52 and Q 53 have the functions equivalent to those of the MOSFET's Q 1 , Q 2 and Q 3 , respectively, in FIG. 1. In this preferred embodiment, there are provided MOSFET's Q 54-1 , Q 54-2 , . . . Q 54-n for deriving a plurality of output currents I out 1, I out 2, . . . I out n. In this instance, it is possible to differently preset the coefficients of variations of the respective output currents I out 1, I out 2, . . . , I out n with respect to the input voltage by varying the ratio of channel width/channel length of the respective MOSFET's Q 54-1 , Q 54-2 , . . . , Q 54-n . The circuit according to this preferred embodiment can be effectively utilized, for example, as a plurality of weighted current sources for feeding a D/A converter or an A/D converter, by respectively weighting the current values of the currents flowing through the MOSFET's Q 54-1 , Q 54-2 , . . . Q 54-n , respectively. In the preferred embodiment illustrated in FIG. 6, control of gate voltages of enhancement type MOSFET's Q 65 and Q 66 serving as load elements is effected by means of an output of an amplifier 68 which generates an inverted output proportional to a sum of voltages at points 11 and 12. In other words, this preferred embodiment employs active loads as load elements, and in this embodiment a sum of voltages at drain electrodes of input MOSFET's Q 61 and Q 62 is negatively fed back to the gate electrodes of the MOSFET's Q 65 and Q 66 which serve as the active loads. In the embodiment lacking such negative feedback as shown in FIG. 1 or 2, as the input voltage approaches the voltage V DD of the first voltage source, the voltages at the drain electrodes of the input MOSFET's will change in the direction for approaching the voltage V SS of the second voltage source, and eventually the input MOSFET Q 1 goes out of the saturation region, so that it cannot achieve the desired operation. This phenomenon restricts the input voltage range of the circuit shown in FIG. 1 or 2. However, if negative feedback is effected as shown in FIG. 6, the voltage changes at the drain electrodes of the input MOSFET's Q 61 and Q 62 can be suppressed to small changes, and hence the input voltage range can be expanded. One example of a practical circuit arrangement according to the above-described embodiment is illustrated in FIG. 7. In this circuit arrangement, MOSFET's Q 72 and Q 73 are transistors having the same configuration and the same threshold voltage, and a parallel combined output of these two MOSFET's controls an output of a ratio circuit consisting of a load element 71 and a MOSFET Q 74 . Now description will be made with regard to examples of application of the circuit according to the present invention. In an oscillator circuit, wherein an oscillation period is determined approximately in proportion to a time required for charging or discharging a capacitor up to a predetermined voltage by means of a current source, by employing the circuit according to the present invention as the current source for charging or discharging the capacitor, one can construct an oscillator circuit in which an oscillation frequency varies in a linear relationship with respect to an input voltage. Such an oscillator circuit is essentially necessary for forming a phase-locked loop (PLL). One example of a circuit arrangement of such an oscillator is illustrated in FIG. 8. In this figure, a MOSFET Q 4 is an output transistor of a circuit 100 according to the present invention, and a MOSFET Q 82 is a transistor having a sufficiently large current amplification factor as compared to that of the MOSFET Q 4 . A Schmitt trigger circuit 14 has an input point 15 and an output point 16. A capacitor 13 has one end connected to the input point 15 and the other end end connected to an arbitrary fixed voltage point. The input-output characteristic of the Schmitt trigger circuit 14 are illustrated in FIG. 9. It is to be noted that in this figure the change of the input voltage V in in the rightward direction along the abscissa and the change of the output voltage V out in the upward direction along the ordinate represent voltage changes in the same direction. Assuming now that the relations of V 2 >V 1 and V 4 >V 3 are satisfied for convenience of explanation, as the input voltage V in is successively increased starting from a voltage lower than the voltage V 1 , at the moment when the input voltage V in has reached the voltage V 2 , the output voltage V out changes from the voltage V 4 to the voltage V 3 , whereas when the input voltage V in is successively decreased starting from a voltage higher than the voltage V 2 , at the moment when it has reached the voltage V 1 , the output voltage V out changes from the voltage V 3 to the voltage V 4 . In FIG. 8, it is assumed that under the condition where the output voltage V out is equal to V 4 , the MOSFET Q 82 changes the capacitor 13 to bring the input voltage V in up to a fixed voltage V 5 that is higher than V 2 and thereby change the output voltage V out to V 3 , whereas under the condition where the output voltage V out is equal to V 3 , the MOSFET Q 82 is in a cut-off condition, while the MOSFET Q 4 in the circuit 100 of the present invention discharges the capacitor 13, so that the input voltage V in is gradually lowered and eventually it reaches V 1 , when the output voltage V out is again raised to V 4 . If the current amplification factor of the MOSFET Q 82 is so high that the time required for the MOSFET Q 82 to change the capacitor 13 and bring the input voltage V in to V 5 when the output voltage V out is V 4 is sufficiently shorter than the time required for the MOSFET Q 4 to discharge the capacitor 13 and bring the input voltage V in to V 1 when the output voltage V out is V 3 , then the oscillation period of this oscillator circuit is approximately equal to the time required for the current generated at the drain electrode of the MOSFET Q 4 as an output current according to the present invention to discharge the capacitor 13 and change the voltage across the capacitor 13 from V 5 to V 1 . Another example of similar oscillator circuits is illustrated in FIG. 10. In this figure, MOSFET's Q 22-1 and Q 22-2 are output transistors according to the present invention, and an oscillator circuit 24 is an oscillator circuit whese oscillation period is proportional to the time required for discharging a capacitor 23 by means of an external current source (in this instance, the MOSFET's Q 22-1 and Q 22-2 ). One example of such an oscillator circuit constructed by MOSFET's is illustrated in FIG. 11, in which MOSFET's Q 30 , Q 31 , Q 36 and Q 39 are enhancement type MOSFET's and MOSFET's Q 37 and Q 38 are depletion type MOSFET's. As described above, according to the present invention a difference between currents flowing through two MOSFET's can be obtained through a relatively simple method, and so, the invention has a great effect in the case where it is desired to derive a difference current as in the case where a linear voltage-current characteristic is desired to realize in a MOSFET circuit. Now more detailed description will be made on the circuit construction of the active load as used in the preferred embodiment illustrated in FIG. 6. Heretofore, in a linear integrated circuit employing MOSFET's, a circuit having a common current source similar to that used in an integrated circuit of bipolar transistors has been used as a differential amplifier circuit. One typical example of such a known circuit in the prior art is illustrated in FIG. 12. In FIG. 12, when voltage variations in the same directions are applied to input terminals 86 and 87, that is, upon applying the so-called in-phase input, a current flowing through a first branch including MOSFET's Q 81 and Q 83 and a current flowing through a second branch including MOSFET's Q 82 and Q 84 are equal to each other. Moreover, the sum of these currents is constant owing to the action of MOSFET Q 85 , so that the currents flowing through the respective branches would not change, and accordingly voltages at output terminals 88 and 89 would not change. Whereas, when voltage variations in the opposite directions are applied to the input terminals 86 and 87, that is, upon applying the so-called differential input, the current flowing through the first branch including the MOSFET's Q 81 and Q 83 and the current flowing through the second branch including the MOSFET's Q 82 and Q 84 are subjected to variations in the opposite directions to each other, so that a difference would be produced between the respective currents, though the sum of the respective currents is held constant owing to the action of the MOSFET Q 85 , and the difference is observed as a voltage difference between output terminals 88 and 89 by the actions of the load elements Q 83 and Q 84 . As described above, the circuit shown in FIG. 12 would not produce any change in the output in response to an in-phase component of the input, but it would amplify only a differential component of the input. As described above, in order for the heretofore known circuit shown in FIG. 12 to operate as a differential amplifier, it is necessary that a constant current flows through the drain-source path of the MOSFET Q 85 , and in order that the constant current flows independently of the voltage at the junction 93, the MOSFET Q 85 must be held in a saturation region. To that end, representing the threshold voltage of the MOSFET Q 85 by V T85 , the bias voltage applied to the gate electrode of the MOSFET Q 85 by V B and the voltage at the junction 93 by V 93 , it is only ncessary to fulfil the following relation: V.sub.B -V.sub.T85 <V.sub.93 Accordingly, representing the voltage of the second voltage source by V SS , the voltage V 93 can be lowered to the proximity of the voltage V SS by selecting the bias voltage V B at a value that is only a little larger than V SS +V T85 . However, as the bias voltage V B is lowered for the above-mentioned purpose, the current amplification factor of the MOSFET Q 85 must be increased by the corresponding amount, this means to increase the channel width of the MOSFET Q 85 , and consequently, the geometrical dimensions of the MOSFET Q 85 are increased. Because of this increase of the geometrical dimensions, in practice, the bias voltage V B can be lowered only to the extent of about V SS +2V T85 , and accordingly, the voltage V 92 can be lowered only to the extent of about V SS +V T85 . Since the voltages applied to the input terminals 86 and 87, respectively, must be higher than the voltage V 93 at least by the common threshold voltage V T of the MOSFET's Q 81 and Q 82 , the lower limit of the allowable in-phase input voltages to the differential amplifier circuit shown in FIG. 12 is at most equal to the following value: V.sub.SS +V.sub.T85 +V.sub.T Since V T85 is normally equal to the common threshold voltage V T , the in-phase input voltages in this instance cannot be chosen lower than the value that is higher than the voltage V SS of the second voltage source by about twice the threshold voltage V T . However, recently in a MOSFET integrated circuit the demand for lowering the power supply voltage has been remarkable. Therefore, with the aforementioned fact that in the heretofore known circuit shown in FIG. 12 the lower limit of the in-phase input must take a value that is higher than the second power supply voltage V SS by about twice the threshold voltage of the enhancement type MOSFET, there is a big shortcoming that lowering of the power supply voltage is restricted in view of the necessity of obtaining a sufficiently large in-phase input region. The concept of the previously discussed active load which has been proposed according to the present invention, can be expanded to a differential amplifier having a novel circuit arrangement which has a broader in-phase input voltage range than the known differential amplifiers in the prior art. One example of improved differential amplifiers according to the present invention will now be described. In FIG. 13, MOSFET's Q 93 and Q 94 are MOSFET's prepared so as to have manually matched electric characteristics, the source electrode of the MOSFET Q 93 is connected to a first output terminal 88, and the source electrode of the MOSFET Q 94 is connected to a second output terminal 89. The respective drain electrodes are both connected to a first voltage source 80 having a voltage V DD , and the respective gate electrodes are both connected to an output of an amplifier 97. MOSFET's 81 and 82 are also MOSFET's prepared so as to have mutually matched electric characteristics. The drain electrode of the MOSFET Q 81 is connected to the first output terminal 89, its gate electrode is connected to a first input terminal 86 and its source electrode is connected to a second voltage source 91. The drain electrode of the MOSFET Q 82 is connected to the second output terminal 89, its gate electrode is connected to a second input terminal 87 and its source electrode is connected to the second voltage source 91. The amplifier 97 inverts and amplifies the sum of the output voltage at the first output terminal 88 and the output voltage at the second output terminal 89, and applies the amplified voltage to the gates of the MOSFET's Q 93 to Q 94 , respectively. Now the operation of the preferred embodiment shown in FIG. 13 will be described. The voltage variations in the same direction generated at the output terminals 88 and 89 are inversely amplified by the amplifier 97, and the output of the amplifier 97 is applied to the gates of the MOSFET's Q 93 and Q 94 . The voltage applied to the gate electrodes of the MOSFET's Q 93 and Q 94 in this way acts upon these MOSFET's in the direction for offsetting the voltage variations originally generated at the output terminals 88 and 89. Under the ideal condition that the absolute value of the gain of the amplifier 97 is infinite, the voltage variations in the same direction generated at the output terminals 88 and 89 are perfectly offset, and consequently, no voltage variation occurs at the output terminals 88 and 89. On the other hand, the voltage variations having the same magnitude and opposite directions generated at the output terminals 88 and 89 would not influence the output of the amplifier 97 because the sum of the voltage variations is zero, and hence the voltage variations would not be offset. Voltage variations in the same direction applied to the input terminals 86 and 87, that is, the so-called in-phase input voltages art to generate voltage variations in the same direction at the output terminals 88 and 89, and therefore, in this case the voltages at the output terminals 88 and 89 would not be altered by the action of the amplifier 97, as described above. On the other hand, voltage variations in the opposite directions applied to the input terminals 86 and 87, that is, the so-called differential input voltages act to generate voltage variations in the opposite directions at the output terminals 88 and 89, and hence these voltage variations would not be offset as described above. As discussed above, the illustrated circuit is provided with desired characteristics as a differential amplifier circuit which amplifies only a differential input without generating any variation at the outputs in response to an in-phase input. Considering now the limit of the in-phase input voltages for sustaining the operation of the illustrated differential amplifier when the in-phase input voltages are made to approach the voltage of the second voltage source 91 in the preferred embodiment shown in FIG. 13, the differential amplifier is operable until the MOSFET Q 81 or Q 82 becomes cut off, and accordingly, the differential amplifier can operate until the in-phase input voltages reach the voltage that is higher in N-channel elements or lower in P-channel elements than the voltage of the second voltage source 91 by the threshold voltage of the MOSFET's Q 81 and Q 82 . Recalling now the fact that in the heretofore known differential amplifier illustrated in FIG. 12 the in-phase input voltages were allowed to approach the voltage of the second voltage source 91 only as close as about twice the threshold voltage of the MOSFET's, the advantage obtained by the preferred embodiment of the present invention illustrated in FIG. 13 will be quite obvious. In the circuit shown in FIG. 13, even if MOSFET's, resistor elements or other elements for adjusting a frequency response are disposed between the drain electrode of the MOSFET Q 93 and the first voltage source 80 and between the drain electrode of the MOSFET Q 94 and the first voltage source 80, or between the drain electrode of the MOSFET Q 81 and the output terminal 88 and between the drain electrode of the MOSFET Q 82 and the output terminal 89, and the respective locations are connected via these elements, so long as they are conductively communicated with respect to D.C. currents, these connections would not interfere with the effect of the present invention. However, it is not favorable to connect resistor elements or other elements between the source electrodes of the MOSFET's Q 81 and Q 82 , respectively, and the second voltage source 91, because the allowable range of the in-phase input is narrowed by the amount equal to the voltages appearing across these connected elements. In addition, it must be carefully done to connect other elements between the source electrode of the MOSFET Q 93 and the output terminal 88 and between the source electrode of the MOSFET Q 94 and the output terminal 89, because sometimes the variations at the output of the amplifier 97 would be hardly reflected to the voltage variations at the output terminals, and in the case where the gain of the amplifier 97 is finite, the variations of the outputs in response to an in-phase input could not be sufficiently suppressed. FIG. 14 shows a more detailed circut arrangement of the embodiment illustrated in FIG. 13. The circuitry consisting of MOSFET's Q 101 , Q 102 , Q 103 , Q 104 and Q 105 in FIG. 14 is one example of a practical circuit arrangement of the amplifier 97 in FIG. 13. The MOSFET's Q 101 and Q 102 are MOSFET's prepared so as to have mutually matched electric characteristics, their respective drain electrodes are both connected to the first voltage source 80, their respective source electrodes are both connected to a junction 46, and their gate electrodes are respectively connected to a first output terminal 88 and a second output terminal 89. The drain electrode of the MOSFET Q 103 is connected to the junction 46, its source electrode is connected to the second voltage source 91, and its gate electrode 47 is applied with a bias voltage. The gate electrode of the MOSFET Q 104 is connected to the junction 46, and the source electrode thereof is connected to the second voltage source 91. The MOSFET Q 105 is a load element, its drain electrode is connected to the first voltage source 80, and its source electrode and gate electrode are connected to the drain electrode of the MOSFET Q 104 and also connected to the gate electrodes of the MOSFET's Q 93 and Q 94 . The circuitry consisting of the MOSFET's Q 101 , Q 102 and Q 103 form a source-follower circuit which responds the sum of the voltage variations applied to the gate electrodes of the MOSFET's Q 101 and Q 102 , respectively, to derive an output at the junction 46, and the above-referred sum of the voltage variations is transmitted to the subsequent stage as a voltage variation at the junction 46. The MOSFET's Q 104 and Q 105 form a so-called inverter, which inverts and amplifies the voltage variation at the junction 46 and applies the invertedly voltage change to the gate electrodes of the MOSFET's Q 93 and Q 94 . Accordingly, the circuitry consisting of the MOSFET's Q 101 , Q 102 , Q 103 , Q 104 and Q 105 can achieve the desired amplifier operation. As described in detail above, according to the present invention there is provided a differential amplifier circuit which has a broader in-phase input voltage range that the differential amplifiers in the prior art, and especially, the present invention can provide a great advantage upon lowering the power supply voltage.

A linear voltage-current converter circuit having a simplified circuit structure and operable over a wide voltage range is disclosed. The circuit comprises a first transistor having a drain connected to a power voltage through a first load element, a second and a third transistor having drains connected to the power voltage through a second load element, means for supplying gates of the first and second transistor with voltage signal, means responsive to a voltage difference at drains of the first and second transistors for controlling a gate voltage of the third transistor so as to reduce the voltage difference to zero, an output transistor, and means for supplying a gate of the output transistor with the same voltage as the gate voltage of the third transistor.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dot-matrix printing device for calculating and accounting machines, typewriters and other printing office machines, wherein a series of striking elements in the proximity of the recording medium are movable transversely with respect to the medium and are adapted to be actuated by the armatures of corresponding electromagnets for impressing the individual dots of each character. 2. Description of the Prior Art A series-parallel dot-matrix printing device is known wherein electromagnets actuating striking elements in the form of flexible wires have their cores fixed to the frame of the machine and their armatures have fixed to them the corresponding flexible wires, which are guided in the proximity of the recording medium by corresponding guide tubes fixed to a slide which is aligned with respect to the printing line. The slide is moved with a reciprocating motion parallel to the printing line so as to allow the ends of the wires to shift along the rows of the character matrix. The electromagnets are actuated selectively for printing the dots disposed in the rows of the matrix. In order to limit the lateral stresses exerted on the armatures of the electromagnets and on the guide tubes and to permit a sufficient and uniform action at the printing ends of the wires, the wires themselves are relatively long and are arched along a wide radius of curvature in order to accommodate the movements of the slide relative to the electromagnets. A device of this type becomes complex, bulky and costly because of the further need to connect the printing wires, which have high hardness and flexibility characteristics, individually to the armatures, of which high magnetic characteristics are required. A series-parallel dot-matrix printing device is also known wherein the printing elements are constituted by styluses which are relatively short and rigid and fixed to cylindrical armatures of corresponding electromagnets of the hollow-core, solenoid type. The guides of the styluses and the electromagnets are fixed to a carriage shifted with a reciprocating motion parallel to the platen. This device requires a carriage and a corresponding guide structure which are rather heavy and bulky because of the need to absorb the reaction of all the armatures when printing takes place. The driving mechanism of the carriage itself has to be rather strong and therefore bulky and costly. There is likewise known a series-parallel dot-matrix printing device wherein the striking elements are constituted by projections aligned with the printing line and formed at the ends of corresponding leaf springs in such manner as to form a comb. The springs are fixed on a carriage and are moved with a reciprocating motion parallel to the line so that each projection may print all the dots of a row of the matrix of a corresponding character. The end of each spring is adjacent the core of an electromagnet so as to be selectively attracted by the core itself and be released to print the corresponding dot, using the energy stored in the spring. A device of this type has the disadvantage of requiring electromagnets of relatively large dimensions and considerable energy for activating the electromagnets, which makes this device costly. A dot printer operating on telegraph tape is known wherein the dots of a row of the character matrix are printed in parallel by corresponding bars connected by means of springs to a frame moved forward and backward by an actuating eccentric in front of the printing point. Each bar can be coupled selectively to the armature of an electromagnet to be left inoperative or to be actuated for printing by the actuating eccentric. A device of this type is very complex and costly and, moreover, cannot be used advantageously in page printers because of the high construction tolerances required by the arrangement of the bars in parallel. There is also known a serial printing device having seven flexible printing wires, wherein the free ends are vertically aligned by a resin guide. The other ends are each fixed to corresponding armatures arranged in a semi-circle and normally retained on the pole pieces of a magnetic core by the magnetic field generated by a permanent magnet and in opposition to the action of respective printing springs. The device, including the magnetic circuit, the armatures, the wires and the guides, is borne by a carriage movable transversely of the printing line. In the proximity of each armature there is moreover prearranged in the magnetic circuit a winding which, when it is energised, creates a magnetic field opposed to that of the permanent magnet, which allows the striking spring to actuate the wire for printing the dot. In this device, the recovery of the armature must be effected by the magnetic force of the permanent magnet in opposition to the action of the striking spring. The field of the permanent magnet must be fairly intense, the dimensions of the permanent magnet therefore become considerable and the energy required for printing the dot, although lower than in printing with positive actuation of the wire, is nevertheless high and requires an electronic control of high power. For these reasons, the device can find application only in those printers in which the problems of cost and size are not important. There has also been proposed a printing device provided with a series of flexible wires which are also aligned vertically and fixed to corresponding armatures. These armatures, in turn, are retained against the pole pieces of an electromagnet by the magnetic field generated therein by the energising current of the electromagnets themselves and in opposition to the action of striking springs. By de-energising each electromagnet, the striking spring actuates the wire for printing the dot and a common cam brings the armature back into contact with the pole pieces of the electromagnet. In this device, since the electromagnets themselves must create the force necessary for retaining the armatures, with a very limited air gap, a relatively low pulse energy is required, but, since the styluses are generally in the inoperative position, the windings of the electromagnets are constantly traversed by the energising current. The dimensions of the electromagnets are therefore large and necessitate a relatively high average energising energy which requires a rather costly supply. SUMMARY OF THE INVENTION The object of the present invention is to provide a simple and economic series-parallel dot printing device of small dimensions wherein the inertias of the moving parts are reduced to the maximum degree and which requires very limited consumption of energy. According to the present invention there is provided a dot-matrix printing device for a printing office machine, wherein a series of striking elements in the proximity of the recording medium are movable transversely of the medium for printing dots in different locations and are adapted to be actuated by the armatures of corresponding electromagnets for impressing individual dots of characters, the striking elements being substantially rigid bars guided in the proximity of the recording medium by a movable guide which effects the transverse movement and each electromagnet having a fixed core and a movable armature in articulated engagement with the corresponding bar. The invention makes it possible to reduce to the minimum the dimensions of the striking elements and the inertias of the masses having a reciprocating motion, which are limited here to the guides of the ends of the bars, and it has been possible to optimise the magnetic circuit, both from the point of view of dimensions and of efficiency and simplicity of construction. Another object of the invention is to provide a dot printing device having low pulse energy consumption, like those devices which utilise electromagnets subject to control for actuating the printing elements, and with a low average-energy consumption, as in those devices in which the retention of the wires is achieved by the force of a permanent magnetic field. There is therefore provided a device in accordance with the invention, wherein each armature is provided with an actuating spring which tends to move the armature away from the core of the electromagnet, means establishing a bias magnetic flux such as to keep the armature at rest in opposition to the action of the actuating spring and a winding which can be energised selectively to generate a flux opposed to the bias flux so as to allow the actuating spring to move the armature away from the core for impression of a dot, the device including a reloading member which acts on the armatures to bring them back into contact with the cores of the electromagnets. A further object of the invention is to provide a dot printing machine having low constructive and testing cost, without effecting neither the reliability nor the printing quality. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail, by way of example, with reference to the accompanying drawings, wherein: FIG. 1 is a plan view, partly in section, of a printing device embodying the invention; FIG. 2 is a section on the line II-II of FIG. 1; FIG. 3 is a section on the line III--III of FIG. 1; FIG. 4 is a section on the line IV--IV of FIG. 3; FIG. 5 is a circuit diagram for the control of the printing device; FIG. 6 is a diagram showing the shape or nature of a number of signals of the circuit of FIG. 5; FIG. 7 is a diagram illustrating the printing scheme of the device; FIG. 8 is a plan view of a modified form of the printing device; FIG. 9 is a section on the line IX--IX of FIG. 8; FIG. 10 is a side view from the left, partly in section, of the device of FIG. 8; FIG. 11 is a section on the line XI--XI of FIG. 8; FIG. 12 is a section on the line XII--XII of FIG. 11; FIG. 13 is a diagram illustrating a detail of the device of FIG. 8 on a larger scale; and FIG. 14 is a diagram showing various operating modes of the printing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT According to the preferred embodiment of the invention, the printing device includes a frame 11, 411 (FIGS. 1 and 8) constituted by a base plate 14, 414 of ferromagnetic material and two vertical sides 12, 412 and 13, 413 in which a platen 15, 415 supporting a sheet of paper 16, 416 is journalled. In front of the platen 15, 415 there is arranged a horizontal slide 18, 418 which can slide in the sides 12, 412 and 13, 413 parallel to the platen 15, 415. On the slide 18, 418 there is mounted a series of bars 20, 420 which are parallel to one another and slidable individually in guides 19, 419 (FIGS. 2 and 10) of the slide 18, 418. Each bar 20, 420 has a thickness of 0.3 mm and has one end 21, 421 tapered in the form of a wedge to define a printing tip of substantially square cross-section. Interposed between the sheet of paper 16, 416 and the bars 20, 420 there is arranged an inked ribbon 22, 422 of known type. On the slide 18, 418 there is mounted a block 120, 520 of plastics material provided with openings 121, 521 in which the printing ends 21, 421 of the bars 20, 420 are accommodated. This block 120, 520 prevents the inked ribbon 22, 422 touching the bars 20, 420 when the latter are not actuated. Moreover, when the inked ribbon is put on, the length of ribbon interposed between the bars and the platen 15, 415 is prevented from being able to foul the said bars 20, 420. Each bar 20, 420 is provided with a groove 23, 423 in which there is seated the upper end 24, 424 of an armature 26, 426 of a control electromagnet 27, 427. Each armature 26, 426 is of ferromagnetic material and has its lower end 29, 429 shaped in the form of a fork which is accommodated in the base plate 14, 414. Moreover, each armature 26, 426 co-operates with a corresponding pole piece 32, 432 of the electromagnet 27, 427. The pole pieces 32, 432 are formed as tongues of a single plate 30, 430 (FIGS. 1 and 8) of ferromagnetic material which is connected to the plate 14, 414 through blocks 33, 433 of non-magnetic material and clamping screws 34, 434 (FIGS. 2 and 10). Between the plate 30, 430 and the plate 14, 414 there is arranged a permanent magnet 35, 435 constituted, for example, by a strip of magnetic rubber. This magnetic rubber is compressed between the said two plates, so that air gaps are avoided, and creates a constant magnetic bias flux between the plate 14, 414 and the pole pieces 32, 432 which keeps the armatures 26, 426 in contact with the pole pieces 32, 432. Around each pole piece 32, 432 there is arranged a spool 36, 436 of plastics material. Each spool 36 (FIG. 2) is integral with a bracket having a locating peg 37 inserted in a corresponding hole 38 in the base plate 14. On each spool 36, 436 (FIGS. 2 and 10) there is wound the turns of an energising coil 40, 440 through which electric current does not normally flow and which can be energised to cancel out the bias flux in the corresponding pole piece 32, 432. Between the spools 36, 436 and the armatures 26, 426 there is arranged a single support 42, 442 of plastics material which is fixed by means of screws 39 (shown only in FIG. 1) to the base plate 14, 414 and is provided with through holes 43, 443 for housing the ends of the pole pieces 32, 432. A series of springs 45, 445 tend to urge the armatures 26, 426 towards the platen 15, 415 in opposition to the action of the flux created by the permanent magnet 35, 435. More particularly, in the support 42 (FIGS. 1 and 2), in correspondence with each armature 26, there is formed a cylindrical recess 44 inside which there is arranged one of the springs 45, which is of spiral type and is compressed between the bottom of the recess 44 and the corresponding armature 26. Except when a winding is energised, the action of the bias flux prevails over the action of the spring. The slide 18, 418 (FIGS. 1 and 8) and the bars 20, 420 are caused to move with a reciprocating motion in front of the platen 15, 415 by shifting means which comprise an electric motor 50, 450, a cam 58, 458 set in rotation by the motor 50, 450, and cam followers 59, 459 and 60, 460 which co-operate with the cam 58, 458 and are connected in turn to the slide 18, 418. The motor 50, 450 rotates a worm 55, 455 in mesh with a corresponding gear 56, 456 mounted rotatably on a vertical spindle 57, 457 of the frame 11, 411. The motor 50 is mounted on a third vertical side member 51 of the frame 11 and has its driving shaft 52 connected through an axially sliding flexible coupling 53 to the worm 55. On the spindle 57, 457, fast with the gear 56, 456, is mounted the cam 58, 458, with which the cam followers 59, 459 and 60, 460 co-operate. A spiral spring 123, 523 stretched between a point 124, 524 of the cam follower 59, 459 and a point 125, 525 of the cam follower 60, 460 holds the two cam followers 59, 459 and 60, 460 constantly against the edge of the cam 58, 458 in order to take up any possible play due to wear. The cam follower 59 is carried by a horizontal slider 62 which is guided in the side members 12 and 13 of the frame 11, and the cam follower 60 is carried by a plate 128 which is connected to the slider 62. This slider is provided with a slot 65 (FIGS. 1 and 2) into which a bottom shank 66 of the slide 18 is inserted so as to render the slider 62 and the slide 18 fast with one another. The cam 58, 458 (FIGS. 1 and 8) is shaped in such manner as to cause the slide 18, 418 to perform an oscillation the amplitude of which is substantially equal to the width of two print characters along a printing line on the sheet of paper 16, 416. More particularly, each bar 20, 420 is adapted to print two characters (FIG. 7) dot by dot in a 7 × 5 matrix. The cam 58, 458 which controls the movement of the slide 18, 418 is shaped so that the bars 20, 420 are shifted at substantially constant speed in the spaces in which the characters are to be printed and accelerate and decelerate during the spaces between two characters. Moreover, in order also that the first and last dot of each character row may be equidistant from the other dots, the effective stroke of the bars 20, 420 is greater than the distance between the extreme dots of a row of the matrix. Furthermore, the width of each upper part 24, 424 (FIGS. 1 and 8) of each armature 26, 426 is substantially equal to the amplitude of the said oscillation, so that each armature 26, 426 always co-operates with the same bar 20, 420 during the movements of the latter in front of the sheet of paper 16, 416. Also fast with the gear 56, 456 (FIGS. 3 and 9) is a second worm 68, 468 which has a pitch varying along its circumference and is in mesh with the teeth of a toothed wheel 69, 469 mounted rotatably on a horizontal spindle 70, 470 supported by the side members 13, 413 and 51, 451 (FIGS. 1 and 8). The toothed wheel 69, 469 transmits the motion to the platen 15, 415 via a set of gears 72, 472. To the worm 55, 455 there is keyed a shaft 73, 473 which is journalled in the side members 12, 412 and 13, 413 and rotates a reloading member 74, 474 comprising a cam which co-operates with the armatures 26, 426 to bring them cyclically back into contact with the corresponding pole pieces 32, 432. A synchronising disc 76, 476 (FIGS. 4 and 12) is mounted rotatably on the vertical spindle 57, 457 and is fast with the cam 58, 458. The synchronising disc 76, 476 (FIGS. 4 and 12) is constituted by a support of plastics material on one surface of which there is deposited, for example by the printed circuit technique, a layer 79, 479 of a metallic material which is a good electric conductor, such as, for example, gold. The conductive layer defines four circular and concentric tracks 85, 485; 86, 486; 87, 487; 88, 488, with which four sensing tongues or strips 80, 480; 81, 481; 82, 482 and 83, 483, respectively, co-operate. More particularly, the track 85, 485 is entirely metallic, the tracks 86, 486 and 87, 487 have insulating zones 89, 489 and 90, 490, respectively, alternating with conducting zones 91, 491 and 92, 492, respectively, and the track 88, 488 has a single conducting zone 93, 493, while the remaining part is of insulating material. Moreover, the conducting zones 91, 491 and 92, 492 are angularly offset from one another and uniformly distributed around the respective circumferences and are also offset with respect to the conducting zone 93, 493 of the track 88, 488. The tongue 80, 480 is constantly supplied with an electric reference voltage and the tongues 81, 481; 82, 482 and 83, 483 are adapted to detect the passage of the conducting zones 91, 491; 92, 492 and 93, 493, respectively, to send corresponding electric timing signals SP1, SP2 and SF1 to a sequencing circuit 96 (FIG. 5) of known type, for example of the type described in U.S. Pat. No. 3,951,247. More particularly, the signals SP1 and SP2 which are derived from the tongues 81 and 82, because of the rebounds to which the contact portions of the tongues may be subjected, are composed of a sequence of groups of pulses SP' (FIG. 6), while the signal SF1 output from the tongue 83 is composed of a sequence of groups of pulses SF'; each group of pulses SF' is generated every twenty groups of pulses SP'. In order to limit the sliding distances between the contacts, the conducting zones and the adjacent insulating zones are disposed around the periphery of the disc so that their width is the minimum possible compatible with the possibility of processing the signals by means of relatively simple circuits. Since the pulses SP1' and SP2' have a relatively short average duration, rebound between the contacts can be recognized as the end of the pulse itself and the resumption of contact with respect to the same conducting zone can be recognised as the beginning of a new pulse SP1' and SP2'. For the purpose of preventing erroneous interpretations of the pulses SP' and SF', the signals SP1, SP2 and SF1 are sent to flip-flops 130, 131 and 132, respectively. The flip-flops 130 and 131 are changed over by the leading edge of each group of pulses SP' and their outputs are connected to a shaping circuit 142 from which issues the shaped signal SP which is the actual timing signal of the printing dots. The flip-flop 132, on the other hand, is changed over by the first leading edge of each group of pulses SF' and has its output connected to a shaping circuit 133 from which issues the shaped signal SF which is the actual timing signal of an elementary printing cycle (20 printing dots to a complete oscillation of the slide 18). The signals SP and SF are sent to a sequencing circuit 96, at which the information relating to the characters which are to be printed arrives on a channel 134 from a calculator 135 to which the printing device may be connected or from a keyboard 136. The sequencing circuit 96 has outputs 137 connected to the selector electromagnets 27, 427 for selective energisation thereof and comprises a first binary counter 138 and a second binary counter 139 which are adapted to count the timing pulses of the signal SP. More particularly, the counter 138 gives a constant signal as output after five SP' pulses and the counter 139 gives an end-of-cycle signal after eighty SP' pulses, as will be described hereinafter. The sensing tongues 80, 480; 81, 481; 82, 482 and 83, 483 are supported by a block 95, 495 (FIGS. 4 and 12) of plastics material which is pivoted on the spindle 57, 457 of the fixed frame 11, 411. The block 95 (FIGS. 1 and 4) is constantly pulled towards the side member 51 of the frame 11 by a spring 99 and has a lug 103 bearing against an adjusting screw 104 which can be screwed into, or out of, the side member 51. In this way, by screwing the screw 104 in or out, a turning action of the block 95 with respect to the side member 51 is produced, which advances or retards the picking-up of the synchronising signals by the tongues 81, 82 and 83. The use of a sliding synchronising disc with the characteristics already described enables a transducer to be obtained which is economic and reliable and which, in contrast to optical or magnetic transducers, does not require high current inputs to be provided for the power supply of the printing device, which is therefore also of limited dimensions for this reason. In order to bring the reloading member 74, 474, which brings the armatures 26, 426 back cyclically against the corresponding pole pieces 32, 432, into phase with the synchronising disc 76, 476, a leaf spring 106 (shown only in FIG. 1) is fixed to the vertical side member 12, 412. This spring 106 has one end 108 disposed between two flanges 109 and 110 of the shaft 74, 473 and is provided with a through hole 111 through which there extends an adjusting screw 112 screwed into the side member 12, 412. The spring 106 constantly tends to shift the shaft 73, 473 to the left. By screwing the adjusting screw 112 in or out, axial movements of the shaft 73, 473 (FIGS. 1 and 8) and the worm 55, 455 with respect to the driving shaft 52, 452 are produced. The axial movements of the shaft 73 are possible because of the presence of the coupling 53. These axial movements cause the gear 56, 456 and the synchronising disc 76, 476 to rotate, while the cam 74, 474 is only shifted axially. Moreover, this adjustment can be made with the machine in operation in order if necessary to correct the phase of energisation of the electromagnets 27, 427 and improve the printing cycle, as will be described hereinafter. The printing device hereinbefore described operates in the following manner. In the inoperative position, the motor 50, 450 is stationary and the slide 18, 418 is stationary at any point of its travel in front of the platen 15, 415. On the switching on of the machine, the counter 138 and 139 of the circuit 96 (FIG. 5) are zeroised in any known manner. By supplying the motor 50, 450 (FIGS. 1 and 8), the worm 55, 455 is set in rotation and consequently causes the cam 58, 458, the worm 68, 468 of varying pitch and the synchronising disc 76, 476 to rotate. The slide 18, 418 and the bars 20, 420 thus begin to oscillate in front of the sheet of paper 16, 416. After each rotation of the worm 68 through 180°, the platen 15, 415 carries out a small rotation so as to cause the sheet 16, 416 to advance by one elementary step (i.e., the pitch between dots in the matrix) which, in accordance with current standards, is about 0.38 mm. The sensing tongues 81, 481; 82, 482 and 83, 483 detect the passage of the conducting zones 91, 491; 92, 492 and 93, 493, respectively, sending corresponding electric timing signals SP and SF to the sequencing circuit 96 (FIG. 5) which controls the energisation of the electromagnets 27, 427. After counting five timing pulses SP', the counter 138 generates a signal enabling printing true and proper. The first pulse SF' which arrives at the sequencing circuit 96 after the enabling signal of the counter 138 gives the start for the printing cycle. It is to be noted that the synchronising disc 76, 476 (FIGS. 3 and 11), the worm 68, 468 of varying pitch and the cam 58, 458 are offset from one another so that the pulses SF' are generated in coincidence with the advance of the platen 15, 415 and when the slide 18, 418 is located shifted completely to the right (FIGS. 1 and 8). The first row of dots is therefore printed from right to left. As has been seen, each bar 20, 420 is adapted to print two print characters for each printing line and, therefore, all the 70 dots of the two 7 × 5 matrices must be covered in successive passes, the inked ribbon 22, 422 being impressed only when a predetermined dot is to be printed on the basis of a predetermined code. Thus, for example, if a bar 20, 420 is to print the numerals one and two (FIG. 7), during the first pass from right to left it imprints the 2nd, 3rd, 4th and 8th dots, while during the second pass, from left to right, it imprints the 12th, 13th, 16th and 20th dots after the paper has been advanced by one elementary step. Referring only to the device of FIGS. 1 to 7, after the second pass and before the third a second phasing pulse SF' is generated. After seven passes the bar 20 completes the printing of two characters, but the slide continues to oscillate at least until the completion of the eighth pass. After eighty pulses SP', in fact, the counter 139 generates an end-of-cycle signal which arrests the motor 50, unless an order to print a following line of characters arrives at the sequencing circuit 96 from the calculator 135 or from the keyboard 136. On sending the end-of-cycle signal after the eightieth pulse SP' from the commencement of the printing, before the motor stops it carries out, owing to inertia, a further small rotation which causes another pulse SF' to be generated and the slide 18 to stop at any point between the ninth and tenth passes. As a rule, the slide 18 stops at least five positions before the completion of the tenth pass. In this way, when the order for another printing cycle is given, a fresh pulse SF' is generated after the counter 138 has generated the enabling signal, having already counted five pulses SP'. By this expedient, while the slide 18 performs three idle passes, line-spacing equal to three elementary advances of the paper 16 is obtained between two successive lines of characters. The cam 58 is shaped so as to cause the slide 18 to shift at constant speed when the bars 20 are located in correspondence with the printing points and to cause it to accelerate and decelerate during its movement between one character and the other, so that the time taken by the bars 20 to bring themselves from the 5th to the 8th column of the matrices may be equal to the unit time which is taken for the movement between two adjacent columns. Moreover, in this way, the conducting zones 91 and 92 of the synchronising disc 76 are also uniformly distributed along the tracks 86 and 87. The printing of a dot takes place in the following manner. Referring to the device according to the two embodiments, the armatures 26, 426 are held when inoperative or at rest with a force of about 100 g. against the corresponding pole pieces 32, 432 by the effect of the bias magnetic field created by the strip 35, 435 of magnetic rubber and in opposition to the force of the springs 45, 445 which is equal to about 70 g. The corresponding selector magnet 27, 427 is now energised by means of a current pulse of about 100 mA for 1 msec. at 18 v. in the coil 40, 440. This creates in the corresponding pole piece 32, 432 a magnetic flux which is opposed to that of the previously existing field, in such manner as to reduce the net magnetic force below the force of the springs 45, 445. The spring 45, 455 can thus urge the armature 26, 426 towards the platen 15, 415, causing it to rotate with respect to its pivoting seat 31, 431. As soon as the armature 26, 426 separates from the pole piece 32, 432, an air gap is formed which further reduces the residual magnetic force and enables the spring 45, 445 to accelerate the armature 26, 426 strongly towards the platen 15, 415. In this way, the bar 20, 420 is also moved at high speed towards the platen 15, 415 and a dot of substantially square section is imprinted on the sheet of paper 16, 416. Once the printing of the dot has been effected, the cam 74, 474 brings the armature 26, 426 back cyclically into contact with the pole piece 32, 432. In this cyclic system with mechanical recovery of the armatures, the energisation of the electromagnet 27, 427 which begins substantially at the same instant when the timing pulses are picked up on the synchronising disc 76, 476 must be in phase with the rotation of the cam 74, 474. In order to optimise the printing cycle, this is effected with the machine in operation by screwing the screw 112 into or out of the side member 12, as has been seen hereinbefore. More precisely, referring to FIG. 14, on a space-time graph v of the cam 74, 474 and between the instant when the command of energisation is given to the electromagnets 27, 427 and the instant when the armatures 26, 426 are close to the platen 15, 415, a fixed time tr of about 2.3 msec. elapses due to the inductances of the magnetic circuit, the mechanical characteristics of the springs 45, 445 and the inertia of the armatures 26, 426. The command of energisation is therefore given at an instant to which is a time tr in advance with respect to the instant t1 when the cam 74, 474 is beyond the path of the armatures 26, 426 towards the platen 15, 415. Moreover, to enable the bars 20, 420 to imprint a dot correctly on the sheet of paper 16, 416, the recovery of the armatures 26, 426 (instant t2) must begin at least after a time ta of the order of about 1.5 msec. With times tr and ts close to the values already given, the nominal printing cycle T becomes about 6.25 msec., which corresponds to a printing speed of two lines per second for the printing system used. During the operation of the device, the supply conditions of the electric motor 50, 450 may vary and, consequently, the speed of rotation of the shaft 52, 452 may also vary, and therefore that of the cam 74, 474. The variations in speed of the motor 50, 450, acting on the cycle T and not on the times tr and ta, alter the conditions of release and recovery of the armatures 26, 426. More particularly, for a lower limit value, corresponding to a curve v", the instant at which the bar 20, 420 touches the platen coincides with the instant t1" at which the cam 74, 474 would tend to arrest the bar. Below this value, the armature 26, 426 would beat against the cam 74, 474 before this has brought itself beyond the path of the armatures 26, 426, thereby preventing the printing of the dot. On the other hand, the speed cannot rise above a value (curve v') such that the instant t2' arrives before the time (tr + ta) has elapsed from the command of energisation of the electromagnets 27, 427, because in this case the armatures 26, 426 would be brought back towards the corresponding pole pieces before the printing of the dot on the sheet of paper 16, 416 has been completed. In the programming of the nominal speed v, account is therefore taken of a safety margin in order to define the range v' and v" within which the speed will always be satisfactory for obtaining a good printing quality. On the other hand, the times (tr and ta), which are optimized for a prototype, may assume values different from one to another in the mass production units. Above all it is desired to have in mass production wide margin of tolerances. Accurate phasing is therefore advisable on each individual unit to take account of the specific characteristics of the unit itself. This can easily be done, with the device in operation, by varying the speed of the motor and thereafter controlling the regularity of the printing in the following manner. First, the motor 50, 450 is brought to the lower limit speed which, for example, may be 10% lower than the nominal speed, and the screw 112 is operated on so that, with good operation, the picking-up of the timing pulses is advanced to the maximum with respect to the phase of the cam 74, 474, so that the striking occurs at the instant t1", precisely at a time tr after the energization of the selector electromagnets 27, 427. Then the motor 50, 450 is brought to the highest speed, which may be, for example, 10% higher than the nominal speed, and it is checked that the instant t2' occurs after the time (tr + ta) has elapsed. It is therefore clear that because of this adjustment or setting-up neither further gradual adjustments in the stationary state on the same unit, nor the use of special test equipment are necessary. In addition to the phasing already described, the device enables phasing to be effected easily of the instant of energization of the electromagnets 27, 427 with respect to the position of the slide 18, 418 along the printing line, for obtaining a good printing quality with the zig-zag method of printing already described. In fact, if the command to the bars 20, 420 is given when they have not yet reached the nominal printing position or have already gone beyond it, the dots of the rows printed in the passes from right to left will be disposed to the right or to the left, respectively, of the theoretical position, and, conversely, the dots of the rows printed in the passes from left to right will be disposed to the left or to the right, respectively, of the theoretical position, thus giving rise to staggering of the dots in the same column of the matrix. For this phasing, the adjusting screw 104 is operated on to shift the tongues 80, 480; 81, 481; 82, 482 and 83, 483 with respect to the synchronising disc 76, 476, thus advancing or retarding in this way the picking-up of the timing signals until such time as the dots in the same column are visibly aligned. This adjustment can therefore also be made with the machine in operation, thus permitting an immediate check by the operator on the result of the printing. The printing device illustrated in FIGS. 8 to 13 has the following modifications with respect to the printing device illustrated in FIGS. 1 to 7. Each bar 420 (FIGS. 8 and 13) has a front end 550 (remote from the platen) guided in a corresponding slot 551 in the support 442, so that the bars 420, instead of shifting in parallel together with the slide 418, oscillate about their pivoting point constituted by the slot 551, thus describing a circular arc with their printing ends 421. This modification with respect to the device of FIG. 1 enables the dimensions of the upper ends 424 of the armatures 426 which co-operate with the grooves 423 of the bars 420 to be reduced. In the device of FIG. 1, in fact, the printing tip 21 of each bar 20 is at a distance of 5.1 mm from the adjacent printing tip, since in accordance with current standards with a step equal to 10 characters per inch a print character has a width of about 1.757 mm and the distance between one character and another is about 0.793 mm. The pitch between two adjacent armatures 26 is 5.1 mm. Moreover, since each printing point is at a distance of 0.364 mm from the adjacent point, the useful stroke of each printing tip 21 of the bars 20, and therefore also of the slide 18 in front of the platen 15, is about 4.004 mm and the actual stroke which, for the reasons already described, is greater than the distance between the extreme dots of a row of the dot matrix, is about 4.3 mm. Consequently, in order to be able to co-operate always with the same bar 20, each armature 26 must have its upper end 24 at least 4.6 mm wide. It is moreover expedient that this end 24 of the armatures 26 be wider than the length of the actual stroke of the bars 20. In fact, their width is 4.8 mm. In this way, the nominal clearance between one armature 26 and the adjacent one comes out at 0.3 mm. Consequently, the tolerances, both at the pivoting seats 31 and at the armatures 26, have to be rather fine. In the device of FIG. 8, on the other hand, while the excursion which the printing tip 421 must perform in front of the platen 415 is still 4.004 mm, it is sufficient that the upper end 424 of each armature 426 be 3.5 mm wide. In this way, the armature 426 being still pitched at intervals of 5.1 mm, the ends 424 have a clearance of 1.6 mm between them and therefore the tolerances may be relaxed. It is obvious that, in order to reduce the dimensions of the armatures 426 further, they could be placed closer to the pivoting point 551, but, since the rise of the circular arc described by the printing end 421 decreases with the approach of the armature 426 to the end 421, the armatures 426 are disposed at an intermediate point so that the rise may be contained within acceptable and practically negligible levels if these are related to the distance at rest between the printing end 421 and the platen 415. It is obvious that this rise could also be completely nullified by shaping the armature 424 so that it is curved and has a central valley or hollow corresponding to the value of the rise which it is desired to take up. In order to permit the bars 420 to oscillate, the guides 419 of the slide 418 are slightly wider than the bars 420 themselves. The play which is created between the guide 419 and the bar 420 is, however, negligible when the bars are inclined, whereas it would be excessive when the bars are in the intermediate positions. Since, however, with the printing system adopted, the points intermediate between two characters are never printed on, there is no disadvantage because of this play. In the modified construction of FIG. 8, instead of the springs 445 being of spiral type, they are constituted by a plurality of leaf springs formed from a single metal plate 560 fixed at the bottom to the support 442 by means of a clamping element 561 of plastics material (FIGS. 8 and 10). The armatures 426 are also modified with respect to the armatures 26. More particularly, on each of these there is formed a horizontal front projection 570 and a projecting element 572, which is also at the front. The horizontal projection 570 has an end 571 in the form of a spherical cap which normally co-operates with the corresponding pole piece 432. On the projecting elements 572, in turn, there bear the terminal portions of the springs 445. The use of a spherical surface which contacts the pole piece 432 enables an air gap which is very limited (of the order of 0.02 mm) and constant to be obtained even if the armature 426 is not perfectly aligned, because of the clearance with which it is pivoted, with a negligible air gap, in its seat 431. Moreover, the area of contact being limited, the specific force between the cap 571 and the pole piece 432 becomes very high. This causes any possible foreign particles or traces of lubricant to remain outside the air gap and not affect the reluctance of the magnetic circuit. The support 442 is also modified with respect to the corresponding support 42. More particularly, in order to receive the ends 571 of the individual armatures 426, a recess 580 is formed in correspondence with each of these. The aim of this recess 580 is to prevent contaminants such as oil, dust or paper fibres, interposing themselves between the armature and the pole piece and thus cause deterioration of the working conditions. Inside the support 442 and over the entire length thereof there is arranged a non-magnetic metal plate 581 provided with slots 582 in which hooked shanks 583 of each spool 436 are engaged. As has been seen hereinbefore, an elementary printing cycle T (printing of a dot) has a duration of about 6.25 msec, which corresponds to a frequency of 160 Hz. Therefore, the shaft 73 and the cam 74 rotate under normal conditions at 9,600 revolutions per minute. In order to deaden the noise due to the impact between the cam 74 and the armature 26 during the recovery of the latter, the cam 74 is constituted by an eccentric and, in correspondence with each armature 26, there is arranged slidably in a groove a ring 190 (FIGS. 1 and 2) of plastics material or sufficiently hard rubber. These rings balance the forces on the various armtures 26 and, by rotating in their respective grooves, act so that throughout the period during which the eccentrics 74 maintain the armatures 26 in contact they limit the wear between the parts in reciprocal movement. As a modification, for the purpose of reducing the speed of rotation of the armature reloading member, in particular on account of the problems of balancing that this requires, the cam 474 (FIGS. 8 and 10) has a profile comprising three lobes offset by 120° from one another. Both the speed of rotation of the shaft 473 and that of the motor 450 are thus reduced in the ratio of 3 to 1. Moreover, in order to reduce the overall dimensions of the device, the motor 450 is fixed to the side member 412 below the platen 415. In this case, in order to reduce the noise due to the reloading of the armatures, between the cam 474 and the armatures 426 there are interposed leaf springs 575 formed from a single metal plate 576 which is fixed to a bent lower portion 577 of the frame 411 by means of a clamping element 578 of plastics material. Each upper end 574 of the leaf springs 575 acts on a spherical cap 573 which is formed on the armature 426 opposite the horizontal projection 570, at the rear of the armature. For the purpose of reducing the time taken to carry out line-spacing between two lines of characters and the wear between the worm and the corresponding pin, the worm 468 (FIGS. 9 and 11) is formed on the periphery of a drum 580 of plastics material and inside which there is formed the profile of the cam 458. Pins 581 of the wheel 469 co-operate with the grooved profile of the worm 468. This profile 468 is formed so that after each 180° of rotation of the drum 580, simultaneously with the reversal of the movement of the slide 418, the platen 415 advances by one elementary step, equal to 0.38 mm, during the first seven passes, and advances by three elementary steps, equal to 1.14 mm, when the slide 418 has completed the seventh pass and is about to perform the eighth (see also FIG. 7). In this way, the sliding for each character between the surface of the worm 468 and the pin 581 is reduced in the ratio of 5 to 1 with respect to the corresponding sliding between the surface of the worm 68 and the teeth of the gear 69. Moreover, the time taken to carry out the line-spacing is substantially equal to that taken for printing a line of dots. To do this, the system for detecting the timing signals is partly modified. More particularly, instead of the pulses SF' being generated every twenty printing dots, they are generated only at the beginning of a line of characters. In fact, the tongue 483 is normally kept spaced from the synchronising disc 476 by a block 590 arranged on the block 495. The tongue 483 is urged cyclically towards the disc 476 by a slider 591 slidable inside the block 495 and controlled in turn by a bail lever 592. The lever 592 is pivoted on a fixed pin 594 (see also FIG. 12) and has an arm 593 in contact with the slider 591 and an arm 595 in contact with the outer profile 596 of the wheel 469. A spring 597 ensures contact between the lever 592 and the wheel 469. The outer profile 596 of the wheel 469 is shaped in such manner as to shift the lever 592 cyclically clockwise (FIG. 11) to bring the slider 591 upward and thus bring the tongue 483 against the corresponding track 488 of the disc 476 only at the beginning of each line of characters. As has already been described, the synchronising disc 76 for picking up the twenty timing pulses SP', which produce the printing of the twenty dots of an elementary printing cycle, has on its tracks 86 and 87 ten conducting zones 91 and 92, respectively, for each track and contact of each of these conducting zones with the corresponding tongues 81 and 82 causes the generation of a timing pulse SP'. Apart from the advantages of easy processing of shaped signals, this also entails reducing to the minimum the dimensions of the disc 76 and the unit sliding effects between the individual tongues and the conducting zones 91 and 92. The separation of the picking-up of the timing signals on two different members (tongues 81 and 82), however, requires careful precision in the arrangement of the tongues 81 and 82 with respect to the synchronising disc 76. Mutual misalignment thereof, in fact, would lead to a phase difference between the picking-up of the pulses of the track 86 and those of the track 87, and a consequent inequality between the distances between the dots of the matrix. Moreover, this could limit the tolerance in the phasing between the synchronising disc 76 and the recovery member 74 for the armatures 26. In order to obviate this possible drawback, the synchronising disc 476 presents the following modifications. In each of the tracks 486 and 487 there are twenty conducting zones 491 and 492, so that at each revolution of the disc 476 twenty pulses SP1' and twenty pulses SP2' are generated. The signals SP1 and SP2 are sent in one case to the set input and in the other case to the reset input of a single flip-flop which has an output connected directly to the sequencing circuit 96. The pulses SP1' act in this way as actual timing pulses, while the pulses SP2', which are out of phase with respect to the pulses SP1', serve only to reset the pulses SP1'. In this way, the timing pulses SP', which correspond to the pulses SP1', are picked up by a single element (tongue 482) and are all equidistant. Moreover, this enables a second flip-flop and a shaping circuit to be saved, compared with the device of FIGS. 1 to 7. Moreover, as another modification, the block 495 is fixed to the frame 411 by means of a clamping screw 495a which engages a slot 598 in the block 495 itself to clamp it removably with respect to the frame 411. By slackening the screw 597, the block 495 can be rotated manually with respect to the frame 411 to advance or retard the picking-up of the timing signals by the tongues 481, 482 and 483 for the purposes seen hereinbefore. Finally, as a last modification, the profile of the cam 458 is modified with respect to that of the cam 58. In fact, as has been seen, the cam 58 is shaped in such manner as to cause the slide 18 to move at constant speed when the bars 20 are in correspondence with the printing points and cause it to accelerate and decelerate during the movement between one character and the other. In practice, this causes each dot to be printed on the fly, while the slide 18 advances with a continuous motion in front of the sheet of paper 16. According to the modification, on the other hand, the cam 458 is shaped in such manner as to cause the slide 418 to move step by step in front of the platen 415, so that the slide 418 itself is stationary when the bars 420 are actuated. For the protection of all the bars 420, a cover 599 (FIG. 10) of plastics material is provided, this being arranged above the support 442. It is moreover to be noted that in order to reduce the cost of the device the armatures 26, 426 are produced by sintering powders of ferromagnetic materials, for example by the method described in the U.S. Pat. No. 3,020,589. It is obvious that other modifications or additions of parts may be made in the printing devices hereinbefore described without departing from the scope of the claims. For example, both the synchronising disc and the cam which controls the movement of the slide 18, 418 may be keyed directly on the shaft 73, 473 which carries the recovery member for the armatures 26, 426, thus eliminating the coupling between the worm 55, 455 and the gear 56, 456. The structure of the electromagnets is not limited by the using of particular printing elements. In particular these elements may be flexible wires instead of rigid bars. Moreover, with respect to the synchronizing signals and to the mechanism for the movements between the printing elements and the recording medium, the invention is not limited to the using in impact printers, but it may applied to non-impact printers as in the electrothermal printing unit of the U.S. Pat. No. 3,951,247, which is incorporated herein as reference. In this last case, instead of using as printing elements the bars actuated by electromagnets, it may be used a corresponding plurality of resistors carried by a corresponding support member.

A dot-matrix printing device for a printing office machine, comprising a series of striking bars in the proximity of the recording medium movable transversely of the medium for printing dots in different locations. The bars are adapted to be actuated by the armatures of corresponding electromagnets for impressing individual dots of characters. The striking bars are guided in the proximity of the recording medium by a movable guide which effects the transverse movement and each electromagnet has a fixed core and a movable armature in articulated engagement with the corresponding bar. Each armature is provided with an actuating spring which tends to move the armature away from the core of the electromagnet. A permanently magnetized rubber establishes a bias magnetic flux such as to keep the armatures at rest in opposition to the action of the actuating springs and a plurality of windings can be energized selectively to generate a flux opposed to the bias flux so as to allow the actuating springs to move the armatures away from the cores for impression of the dots. The device further includes a reloading member which acts on the armatures to bring them back into contact with the cores of the electromagnets.

CLAIM OF PRIORITY [0001] The present patent application claims the priority benefit of the filing date of U.S. provisional application No. 60/921,213 filed Apr. 1, 2007, the entire content of which is incorporated herein by reference. TECHNICAL FIELD [0002] This disclosure relates generally to menu presentation generation for computational machines to facilitate navigation during use of an application. COPYRIGHT NOTICE/PERMISSION [0003] A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. The following notice applies to the software and data as described below and in the drawing hereto: Copyright ©2007, SAP, AG, All Rights Reserved. BACKGROUND [0004] Users of an application can often access the application under different contexts. For example a user can access an application by using a desktop platform, but at a different occasion, may access the same application while using a mobile platform such as a handheld computational machine, which may cause a difficulty for the user. [0005] The menu method of accessing the application can differ significantly between the platforms, and indeed, can even differ among the first two, and a third platform such as an audio-only platform. DESCRIPTION OF DRAWINGS [0006] The disclosure is illustrated by way of example and not limited to the figures of the accompanying drawings, in which like references may indicate similar elements and in which: [0007] FIG. 1 illustrates a mapping between a conventional navigational list and a navigational list according to an embodiment. [0008] FIG. 2 illustrates various presentations for migrating across different hardware platforms according to an embodiment. [0009] FIG. 3 illustrates a software platform for the generation of a menu presentation relative to a given menu orientation according to an embodiment. [0010] FIG. 4 illustrates a time-dependent navigational tool for a radiant-energy menu presentation according to an embodiment. [0011] FIG. 5 illustrates a hand-held platform for accessing any of the menu presentation embodiments. [0012] FIG. 6 illustrates a hand-held platform for accessing any of the menu presentation embodiments. [0013] FIG. 7 illustrates a hand-held platform for accessing any of the menu presentation embodiments. [0014] FIG. 8 is a diagram of a method for presenting a navigational control record of a browsing session according to an example embodiment of the disclosure. [0015] FIG. 9 is a block diagram of a machine in the illustrative form of a computer system within which a set of instructions, for causing the machine to perform any one or more of the methodologies discussed herein, may be executed. [0016] FIG. 10 is a diagram of an architecture according to various embodiments. [0017] FIG. 11 displays two different conventional presentations that can occur between two platforms that present the same application. DETAILED DESCRIPTION [0018] The following description contains examples and embodiments that are not limiting in scope. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of an embodiment of the present disclosure. It will be evident, however, to one skilled in the art that the present disclosure may be practiced without these specific details. [0019] A desktop platform may have an abundance of visual/graphical display area to present a menu with useful navigational targets, but a handheld platform will likely have comparatively limited visual/graphical display area to present the same navigational targets. [0020] With a visual/graphical presentation for example, menu presentations can have a top-accessible origination point with a menu that opens downwardly, a bottom-accessible origination point with a menu that opens upwardly, or even a sideways-opening menu, among others. With a visual/graphical presentation, these differing presentations can occur even with a single standard software package. [0021] A difficulty for the user can arise in the hand-held environment, such as a delivery worker who is returning to his vehicle and at the same time accessing an application with his hand-held platform while walking along a busy thoroughfare. The worker desires to focus his viewing upon traffic, both vehicular and pedestrian, but at the same time access the application within the hand-held platform. [0022] FIG. 11 displays two different conventional presentations that can occur between two platforms that present the same application. [0023] A top-down menu presentation 1101 includes the origination point 1110 such as a menu bar. It may include a first navigational target 1114 that represents a data-access location (DAL) that was first accessed. Several other navigational targets are depicted, such as a second navigational target 1116 that represents a DAL, an intermediate navigational target 1118 that represents a DAL, and a last navigational target 1122 that represents a DAL. A difficulty for a user such as a delivery worker who is accessing the application from a hand-held platform and who may be distracted by traffic, is that he may want to access the DAL represented by the first navigational target 1114 , but he may be positioned starting at the origination point 1110 in the menu. Consequently, the delivery worker may have to push a navigational button several times to reach the DAL represented by the first navigational target 1114 , which may require diverting his eyes significantly long from observing traffic. [0024] A similar problem exists with a bottom-up menu presentation 1102 where the user reaches the desired DAL by visually scanning the menu display. The same software may be used for the presentation 1101 , but the user has migrated to a different hardware platform. The presentation 1102 includes the origination point 1130 such as a menu bar. It also includes a first navigational target 1134 that represents a DAL that was first accessed. Similarly to the top-down menu presentation 1101 , the bottom-up menu presentation 1102 may display several other navigational targets, such as a second navigational target 1136 that represents a DAL, an intermediate navigational target 1138 that represents a DAL, and a last navigational target 1142 that represents the last-accessed DAL. The difficulty for a delivery worker is similar to that depicted with the top-down menu presentation 1101 as for this bottom-up menu presentation 1102 . The delivery worker may want to access the DAL represented by the first navigational target 1134 , but he may be positioned in the menu at the origination point 1130 . Consequently, the delivery worker may have to push a navigational button several times to reach the DAL represented by the first navigational target 1134 , which may require diverting his eyes significantly long from observing traffic if the navigation tasks requires him to visually track the results of his navigational behavior. [0025] Terminology [0026] The following terminology is exemplary but not limiting. A “selectable target” is synonymous with a menu element that can be selected by a user. A “data-access location” (DAL) is accessed by using a selectable target. [0027] A “navigational target” is an accessible target on a presentation of a menu that directs the user to a different location within a given application, or to a different application. [0028] An “object target” is a selectable target on a presentation of a menu that can import or export a file, or a data structure that is stored in memory. [0029] In the various embodiments disclosed herein, there are visual menu presentations, audio menu presentations, tactile menu presentations, and combinations thereof. [0030] FIG. 1 illustrates a comparison between a conventional navigational list and a navigational list that is generated as a menu presentation according to an embodiment. A bottom-up menu presentation 100 , as a conventional menu orientation, includes the origination point 110 such as a menu bar. It may also include the first navigational target 112 that represents a data-access location that was first accessed. The bottom-up menu presentation 100 may display several other navigational targets, such as a second navigational target 114 that represents a DAL, an intermediate navigational target 116 that represents a DAL, and the second to last navigational target 118 that represents a DAL as well as the last navigational target 120 that represents the last-accessed DAL. Again, the difficulty is that a user may want to access the DAL represented by the first navigational target 112 , but the user may be positioned in the menu at the origination point 110 at the onset of starting to navigate to DAL 112 . Consequently, the user may have to push a navigational button several times to reach the DAL represented by the first navigational target 112 , which may require diverting his eyes significantly long from observing traffic in order to ensure that he reaches the desired DAL by visually scanning the menu display. [0031] The bottom-up menu presentation 101 for a given computational machine, according to an embodiment, represents a transformation of the bottom-up menu presentation 100 , such that it is a generation of a menu presentation relative to the given menu presentation 101 . This embodiment includes the origination point 111 such as a menu bar. It may also include the first navigational target 113 that represents a DAL that was first accessed. The bottom-up menu presentation 101 may display several other navigational targets, such as a second navigational target 115 that represents a DAL, an intermediate navigational target 117 that represents a DAL, and the second to last navigational target 119 that represents a DAL as well as the last navigational target 121 that represents the last-accessed DAL. [0032] Where the user likely wants to navigate from the origination point 111 to the first navigational target 113 , only a single, generic command is required such as a single button push, and the first navigational target 113 is accessible accordingly at the onset of starting to navigate to DAL 112 and subsequently reached immediately as a result of the single button push. The computational machine presentation therefore re-arranges the first navigational target 113 in a spatial relationship to a presentation location that is nearer the origination point 111 . Consequently, the user need not divert his attention from traffic, but with haptic knowledge of the menu presentation can navigate more easily from the origination point 111 to the first navigational target 113 . [0033] The “first navigational target 113” may be a most likely or most frequently accessed navigational target 113 to be first accessed when the user has returned to the platform to access data. The most frequently accessed navigational target 113 may also be referred to as a most frequently visited data-access location. For example, a delivery worker may have a queue of deliveries that are electronically stored in data-access locations, and after delivering to a customer, he accesses the application from a hand-held device, and navigates to the first navigational target 113 . Consequently the DAL, accessed at the first navigational target 113 , allows the delivery worker to immediately and with a single action, ascertain his next customer in the delivery queue. Further, the single action does not require diversion of his attention. In a method embodiment, the method includes compiling a list of visited data-access locations. In an embodiment, however, a method may further include monitoring a selection likelihood of a first selectable target such as the first navigational target 113 and a second selectable target such as the second navigational target 115 , and when the second selectable target becomes more likely to be selected than the first selectable target, the method further includes re-arranging the second selectable target to a presentation nearer the origination point, and re-arranging the first selectable target to a presentation less near the origination point than the second selectable target. In other words, the second selectable target is presented as a prominent selectable target or a most recently visited data-access location. In an embodiment, re-arranging the order of selectable targets may occur consistently for all platforms that may be available for use of the same application. [0034] It can be seen that another method embodiment includes a second selectable target and a third selectable target, the method including, where re-arranging the second selectable target because it is less likely to be selected first, to a presentation nearer the origination point, but re-arranging the third selectable target less likely to be selected second, to a presentation nearer the origination point, but the second selectable target is re-arranged to a presentation nearer the origination point than the third selectable target. [0035] FIG. 2 illustrates various presentations 200 for migrating across different hardware platforms (also referred to as “hardware contexts”), according to an embodiment. [0036] A bottom-up menu presentation 201 shows an origination point 211 and then DALs named ORANGE 213 , APPLE 215 , BANANA 217 , and KIWI 219 . These DALs are rearranged according to likelihood of access from the origination point 211 , based upon frequency of use, or based upon likelihood of being used next according to an embodiment. [0037] A top-down menu presentation 203 shows an origination point 231 and then DALs named ORANGE 233 , APPLE 235 , BANANA 237 , and KIWI 239 . These DALs are rearranged according to likelihood of access from the origination point 231 , based upon frequency of use, or based upon likelihood of being used next according to an embodiment. In an embodiment, a user has migrated between two hardware platforms, which display the respective menu presentations, one being bottom-up 201 and the other being top-down 203 . Because the presentation style persists between the two hardware platforms, the user experiences an ease of use despite migrating between the two respective hardware platforms. [0038] A left-to-right sideways menu presentation 205 shows an origination point 251 and then DALs named ORANGE 253 , APPLE 255 , BANANA 257 , and KIWI 259 . These DALs are rearranged according to likelihood of access from the origination point 251 , based upon frequency of use, or based upon likelihood of being used next according to an embodiment. In an embodiment, a user has migrated between two hardware platforms, which display the respective menu presentations, one being bottom-up 201 and the other being left-to right sideways 205 . The user experiences an ease of use despite migrating between the two respective hardware platforms. [0039] A right-to-left sideways menu presentation 207 shows an origination point 271 and then DALs named ORANGE 273 , APPLE 275 , BANANA 277 , and KIWI 279 . These DALs are rearranged according to likelihood of access from the origination point 271 , based upon frequency of use, or based upon likelihood of being used next according to an embodiment. In an embodiment, a user has migrated between two hardware platforms, which display the respective menu presentations, one being bottom-up 201 and the other being right-to-left sideways 207 . The user experiences an ease of use despite migrating between the two respective hardware platforms. [0040] FIG. 3 illustrates a software platform 300 for the generation of a menu presentation relative to a given menu orientation according to an embodiment. In an embodiment, several different domains may be used to access the software platform 300 . In an embodiment, several different hardware contexts may be used to access the software platform 300 . Specialized hardware contexts may use only a portion of the software platform 300 . [0041] In an embodiment, a user may invoke the software platform 300 , and a user domain is recognized thereby. In an embodiment a user FIRST DOMAIN 310 represents a recognition capability of the software platform 300 . Where a user may migrate between hardware contexts, the user may still access the same data from the user FIRST DOMAIN 310 , although he may be using a different hardware context. Other domains are represented, including a user SECOND DOMAIN 312 and so on until a user n th DOMAIN 314 . In an embodiment a given user domain may be an internet-based source through which a user is operating. In an embodiment a given user domain may be a telephonic communications-based source through which a user is operating. [0042] A user may also invoke the software platform 300 by a subsequent hardware context 320 , such as a mobile platform (mobile machine), a desktop platform (desktop machine), a laptop platform (laptop machine), or other platforms. [0043] In an embodiment, the user domain and the hardware platform are recognized by the software platform 300 , and the software platform 300 adapts to the combination for a configuration that is useful for the specific user, but that may adapt for an alternative user. [0044] The software platform 300 also recognizes a relationship, in concert with the given domain and hardware context. In an embodiment, a RELATIONSHIP 0 th 330 is recognized such as a specific customer with specific needs. In an embodiment, the RELATIONSHIP 0 th 330 represents a default relationship, such as a most likely relationship for a given configuration of the software platform 300 . In an example embodiment of the delivery person, the relationship may invoke a specialized subset of a given application, such that the specialized subset has been configured to meet the most useful needs of the delivery person as the user of the software platform 300 . At another time, the delivery person may invoke the software platform 300 that requires a different relationship. For example in the field, the delivery person RELATIONSHIP 0 th 330 maybe useful, but in a reporting meeting such as a headquarters, a different relationship is more useful. [0045] In an example embodiment, the software platform 300 is configured for private individual use such as a wireless telephone user. The RELATIONSHIP 1 st 332 may be configured for the wireless telephone user, and the wireless telephone user may be accessing an email attachment that requires the execution of a software program such as a word processor. Accordingly the RELATIONSHIP 1 st 332 may allow the wireless telephone user to have an efficient session while opening and navigating through the word processor. For example, where the RELATIONSHIP 1 ST 332 is a wireless telephone network, a user such as a delivery person may migrate from a wireless first hardware context to a desktop (subsequent) hardware context 320 and continue working on a task. Accordingly, the bottom-up presentation may be emulated within the desktop (subsequent) hardware context 320 that matches the presentation that was in the wireless telephone first hardware context 320 . [0046] Other relationships are also depicted, including a RELATIONSHIP 2 nd 334 , a RELATIONSHIP 3 rd 338 , and so on until a RELATIONSHIP n th 340 . In an embodiment, the various relationships may represent various different customers who have distinct and specific customer needs the software platform may be designed to handle. [0047] In an embodiment, the RELATIONSHIP 2 nd 334 depicts sub-relationships, including a RELATIONSHIP 2.1 st 333 , a RELATIONSHIP 2.2 nd 335 , and so on until a RELATIONSHIP 2.n th 337 . In an embodiment, the various sub-relationships may represent various different subdivisions within a customer, where each subdivision has distinct and specific customer needs that the software platform 300 may be designed to handle. [0048] For example, a delivery person using, e.g., a wireless FIRST DOMAIN 310 and a mobile first hardware context 320 , may have a selected menu presentation such as bottom-up. The computational machine presentation therefore re-arranges a first navigational target to a presentation location that is nearer the origination point. In other words, the computational machine presentation therefore re-arranges a first navigational target to a presentation location that makes it a prominent navigational target. An associate of the delivery person using, e.g., a wide-area network (WAN) user SECOND DOMAIN 312 and a laptop (subsequent) hardware context 320 , may observe the menu presentation, but it may be identical to the presentation observable by the delivery person, e.g., bottom-up, or it may be a presentation that is different. Further, another associate of the delivery person using, e.g. an internet n th DOMAIN 314 and a desktop (subsequent) hardware context 3 , may observe the menu presentation, but it may be identical to the presentation observable by the delivery person, e.g., bottom-up, or it may be a presentation that is different. In other words, the computational machine presentation therefore re-arranges the first navigational target to a presentation location that is not nearer the origination point, rather, it may be re-arranged in a manner such as is depicted at 100 in FIG. 1 . [0049] In an embodiment, the various sub-relationships may represent various different customer types that are not necessarily related as business entities, but where each subdivision has distinct and specific customer needs for that given customer type that the software platform 300 may be designed to handle. [0050] The software platform 300 recognizes a user domain, a hardware context, a relationship, and a user interface 350 . The user interface 350 can vary even with a single user, as he may migrate among different hardware platforms, but may access the same application from the various different hardware platforms. Examples of various user interfaces (UIs) include a graphical UI 352 , an audio UI 354 , a tactile/motile UI 356 , or an other UI 358 . In an embodiment, any combination of the given UIs may be used to assist the user. In an embodiment, a user migrates between a first hardware platform and a second hardware platform, and retains the same UI presentation to the various illustrated embodiments depicted in FIG. 2 [0051] In an embodiment, a transformation of a bottom-up menu presentation for a given computational machine, such as the menu presentation 101 depicted in FIG. 1 , is carried out with a graphic UI 352 . In an embodiment, however, a visually impaired user may require a different UI. For example, a delivery person may be negotiating movement through vehicular and pedestrian traffic, and an audio UI 354 interface is more useful such that the delivery person may receive auditory feedback and need not divert his vision away from the traffic. The audio UI 354 , however, allows the delivery person to immediately access, e.g., the first navigational target 113 , and an audio signal informs the delivery person that the requested DAL has been accessed. In an embodiment with the delivery person, the delivery person may have tactile-sequential access to the UI 356 , but with a button push, an audio signal informs the delivery person that the requested DAL has been accessed by use of the audio UI 354 . Consequently, a combination graphical UI 352 , audio UI 354 , and tactile/motile UI 356 has been employed to assist the user. [0052] In an embodiment, a user with visually impaired eyesight may use the audio UI 354 with neither graphical, not tactile/motile assistance. In this embodiment, the user makes a single audible command, which the audio UI 354 recognizes, and in an example embodiment, the audible command equivalent to “NAVIGATIONAL TARGET FIRST” but a simplified command such as “push”, which emulates single button push of a tactile/motile UI. [0053] After the software platform 300 recognizes the domain, the hardware context, the relationship and sub-relationship if necessary, and the specific user interface, the software platform 300 accepts a query 360 . A query 360 may be a button push, an audible command, a screen position selection on a graphical UI, or an other query. [0054] Thereafter, a rendering module 370 gives communication feedback through the hardware context 320 to the user. Accordingly, the computational machine presentation may be customized by re-arranging a first selectable target more likely to be selected first, to a presentation nearer the origination point. The software platform therefore allows a user to migrate between hardware contexts 320 , to migrate between domains, and even migrate between relationships, such that the user interface may be re-arranged to simplify or reduce the number and complexity of commands needed to efficiently access the given software. [0055] FIG. 4 illustrates a time-dependent navigational tool for a radiant-energy menu computational machine presentation 400 according to an embodiment. This embodiment includes an origination point 410 . The origination point 410 is depicted with radiant-energy lines, as it represents an audio signal for example. The origination point 410 may also represent a visual presentation such as a single display at a given time. A timeline 408 represents a zeroth time for the origination point 410 , and several other times up to an n th time (t nth ) In an embodiment, a user invokes the origination point 410 by an audible command, and a first navigational target 413 is executed by an audio reply. When the user desires to access the DAL represented by the first navigational target 413 , the user may give a second audible command accordingly. [0056] Should the user, however, choose a different navigational target, several other navigational targets may be broadcast to the user while he waits. FIG. 4 depicts other navigational targets such as a second navigational target 415 that represents a DAL, an intermediate navigational target 417 that represents a DAL, and a second to last navigational target 419 that represents a DAL as well as a last navigational target 421 that represents the last-accessed DAL. This embodiment may be used by the user, for example, where the user is visually impaired. Further according to an embodiment, the user may configure the radiant-energy menu presentation 400 in a given instance where he may be visually distracted by negotiating traffic. At another time, the user may configure a different menu presentation where he may not be visually distracted, but he may have migrated to a different hardware platform. [0057] In an embodiment, the user may want an audio menu computational machine presentation 400 , but has tactile access to his hardware context 320 such as a hand-held computing machine. Where the user likely wants to navigate from the origination point 410 to the first navigational target 413 , a single command such as a single button push is first required, and the first navigational target 413 is presented. The user then may repeat a button push, or, he may give an audible command to access the DAL represented by the first navigational target 413 . Consequently, the user need not divert his attention from traffic, but with audible and haptic knowledge of the menu presentation but will navigate more easily from the origination point 410 to the first navigational target 413 by embracing the audio presentation or the haptic presentation. [0058] FIG. 5 illustrates a hand-held platform 500 for accessing any of the menu presentation embodiments. The hand-held platform 500 can be a computational machine that includes a graphical UI 510 , an audio UI 512 , and a tactile/motile UI 514 . In an embodiment, a software platform such as the software platform 300 or a subset thereof, recognizes the hand-held platform 500 as an appropriate hardware context. The software platform may also recognize a domain, a relationship, and based upon a given likely user, a selected combination of UIs such as some of the UIs 350 depicted in FIG. 3 . The tactile/motile UI 514 is represented as four directional navigation buttons. It can be seen that a given user with the hand-held platform 500 , may access a given application by several combinations, including presenting the most likely to be accessed DAL first in time or closest to an origination point. [0059] FIG. 6 illustrates a hand-held platform 600 for accessing any of the menu presentation embodiments. The hand-held platform 600 includes a graphical UI 610 , an audio UI 612 , and a tactile/motile UI 614 . In an embodiment, a software platform such as the software platform 300 or a subset thereof, recognizes the hand-held platform 600 as an appropriate hardware context. The software platform may also recognize a domain, a relationship, and based upon a given likely user, a selected combination of UIs such as some of the UIs 250 depicted in FIG. 3 . The tactile/motile UI 614 is represented as a toggle navigation button. It can be seen that a given user with the hand-held platform 600 , may access a given application by several combinations, including presenting the most likely to be accessed DAL first in time or closest to an origination point, or by displaying the same UI presentation because the user may have migrated to a different hardware platform. [0060] In an embodiment, the software platform may be web-based accessible, and the specific UI configuration may be programmable into the hardware context, depending upon the specific user profile etc., and the tasks the user will be or is undertaking. [0061] FIG. 7 illustrates a hand-held platform 700 for accessing any of the menu presentation embodiments. The hand-held platform 700 includes a graphical UI 710 , an audio UI 712 , and a tactile/motile UI 714 . In an embodiment, a software platform such as the software platform 300 or a subset thereof, recognizes the hand-held platform 700 as an appropriate hardware context. The software platform may also recognize a domain, a relationship, and based upon a given likely user, a selected combination of UIs such as some of the UIs 350 depicted in FIG. 3 . The tactile/motile UI 714 is represented as a single navigation button. With a single navigation button, and where the software platform assists the user, the hand-held platform 600 , may be used to access a given application by several combinations, including presenting the most likely to be accessed DAL first in time or closest to an origination point. Further with any of the input/output functionalities, a user may wrap around a presented menu if a given navigational target is missed. [0062] Accordingly, a first hand-held platform may be a Pocket PC®, and a second hand-held platform may be a Blackberry®. In other words, a first computation computational machine and a second computational machine belong to a single user, and the user migrates from one to the other, but requires further computation on the second, as a continuing session from the first. Consequently, re-arranging the first selectable target is derived from instructions for the first computational machine. In the first computational machine, the first selectable target is originally presented nearer the origination point. [0063] FIG. 8 is a diagram of a method 800 for presenting a navigational control record of a browsing session according to an example embodiment of the disclosure. [0064] At 802 , the method includes recognizing a hardware context. [0065] At 804 , the method includes recognizing a user interface. [0066] At 806 , the method includes recognizing a query. [0067] At 808 , the method includes at least one of recognizing a domain and a relationship. [0068] At 810 , the method includes presenting a menu layout in a first presentation in a first hardware context. [0069] At 820 , the method includes presenting the same menu layout in the first presentation in a second hardware context. [0070] At 830 , the method includes rendering feedback through the second hardware context. [0071] FIG. 9 is a block diagram of a computing machine 999 in the example form of a computer system 900 within which a set of instructions, for causing the machine 999 to perform any one or more of the methodologies discussed herein, may be executed. For example, computer instructions include generating a computational machine presentation using an origination point for a user and re-arranging a first selectable target more likely to be selected first, to a presentation nearer the origination point. In an embodiment, computer instructions recognize a user who has migrated between a first hardware platform and a second hardware platform, and the instructions are to preserve the UI configuration the user had in the first hardware platform. [0072] In alternative embodiments, the machine operates as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, the machine may operate in the capacity of a server or a client machine in server-client network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The machine may be a personal computer (PC), a tablet PC, a set-top box (STB), a Personal Digital Assistant (PDA), a cellular telephone, a web appliance, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated, the term “machine” shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. [0073] The example computer system 900 includes a processor 902 (e.g., a central processing unit (CPU), a graphics processing unit (GPU) or both), a main memory 904 and a static memory 906 that communicate with each other via a bus 908 . The computer system 900 may further include a video display unit 910 (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)). The computer system 900 also includes an alphanumeric input device 912 (e.g., a keyboard), a user interface (UI) navigation device 914 (e.g., a mouse), a disk drive unit 916 , a signal generation device 918 (e.g., a speaker) and a network interface device 920 . [0074] The disk drive unit 916 includes a machine-readable medium 922 on which is stored one or more sets of instructions and data structures (e.g., software 924 ) embodying or utilized by any one or more of the methodologies or functions described herein. The instructions 924 may also reside, completely or at least partially, within the main memory 904 and/or within the processor 902 during execution thereof by the computer system 900 , the main memory 904 and the processor 902 also constituting machine-readable media. [0075] The instructions 924 may further be transmitted or received over a network 926 via the network interface device 920 utilizing any one of a number of well-known transfer protocols (e.g., hyper-text transfer protocol, HTTP). In various embodiments, the machine 999 is a wireless device and includes an antenna 930 that communicatively couples the machine 999 to the network 926 or other communication devices. Other devices may include other machines similar to the machine 999 , wherein the machine 999 and the other machines operate in an ad-hoc mode of communicator with one and other. [0076] In various embodiments, the network 926 couples the machine 999 to a database 950 . In various embodiments, the database 950 includes data that may be displayed with assistance of the machine 999 by using the video display 910 . [0077] While the machine-readable medium 922 is shown in an example embodiment to be a single medium, the term “machine-readable medium” should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of instructions. The term “machine-readable medium” shall also be taken to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies of the disclosed embodiments, or that is capable of storing, encoding or carrying data structures utilized by or associated with such a set of instructions. The term “machine-readable medium” shall accordingly be taken to include, but not be limited to, solid-state memories, optical and magnetic media, and carrier wave signals. The disclosed embodiments can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. The disclosed embodiments can be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network. [0078] In various embodiments, the machine 999 includes a display generation module 940 . In various embodiments, the display generation module 940 is a software application. In various embodiments, the display generation module 940 includes hardware which may include a memory storage device 942 , which may include software stored on the memory storage device. In various embodiments, display generation module 940 is operable to generate commands to format data to be displayed on the video display 910 according to the various methods described herein. [0079] The embodiments can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. The disclosed embodiments can be implemented as a computer program product, for example, a computer program tangibly embodied in an information carrier, for example, in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, data processing apparatus, for example, a programmable processor, a computer, or multiple computers. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network. [0080] Method operations of any disclosed embodiments and their equivalents can be performed by one or more programmable processors executing a computer program to perform functions of the disclosed embodiments by operating on input data and generating output. Method operations can also be performed by, and apparatus of the disclosed embodiments can be implemented as, special purpose logic circuitry, for example, an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). [0081] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, for example, EPROM, EEPROM, and flash memory devices; magnetic disks, for example, internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in special purpose logic circuitry. [0082] FIG. 10 is a diagram of an architecture 1000 according to various embodiments for generating a computational machine presentation. In various embodiments, the architecture 1000 includes a module 1020 . The module 1020 may be software, hardware, or may be a combination of software and hardware. In various embodiments, module 1020 may include software stored as instructions, for example the instructions 924 associated with the processor 902 in FIG. 9 . In various embodiments, the module 1020 may be the display generation module 940 as shown in FIG. 9 . In various embodiments, the module 1020 includes instructions that may be stored in more than one place within the architecture 1000 . In various embodiments, the module 1020 includes one or more of the following: hardware context recorder 1022 , user interface recorder 1023 , domain recorder 1024 , relationship recorder 1025 , and rendering type recorder 1026 . In various embodiments, the module 1020 is coupled to the data input interface 1010 . In various embodiments, the data input interface 1010 is operable to receive input data 1012 and to provide the module 1020 with the data, such as data derived from a user's navigation through an application. [0083] In various embodiments, module 1020 is coupled to a display driver interface 1030 . In various embodiments, the display driver interface 1030 interfaces with the module 1020 to receive data provided by the module 1020 and provides an output 1032 to control a display. Various embodiments of apparatus, methods, and system have been described herein. Various embodiments include an apparatus comprising a display to provide a visual representation of a generation of a menu presentation relative to a given menu orientation. [0084] Various embodiments include a system comprising a wireless device including an antenna to communicatively couple the wireless devices to one or more other devices, and the wireless device including a display and a display generation module couple to the display, the display generation module to generate commands to cause the display to provide a presentation generation of a menu presentation relative to a given menu orientation. [0085] Various embodiments include a machine-readable medium embodying instructions that, when executed by a machine, cause the machine to display a generation of a menu presentation relative to a given menu orientation. [0086] The embodiments can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. The embodiments can be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network. [0087] Method operations of the embodiments can be performed by one or more programmable processors executing a computer program to perform functions of the embodiments by operating on input data and generating output. Method operations can also be performed by, and apparatus of the embodiments can be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). [0088] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in special purpose logic circuitry. [0089] The embodiments can be implemented in a computing system that includes a back-end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front-end component, e.g., a client computer having a graphical user interface or an Web browser through which a user can interact with an implementation of the embodiments, or any combination of such back-end, middleware, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (“LAN”), a wide area network (“WAN”), and the Internet. [0090] The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. [0091] Certain applications or processes are described herein as including a number of modules or mechanisms. A module or a mechanism may be a unit of distinct functionality that can provide information to, and receive information from, other modules. Accordingly, the described modules may be regarded as being communicatively coupled. Modules may also initiate communication with input or output devices, and can operate on a resource (e.g., a collection of information). [0092] Although an embodiment have been described with reference to specific example embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the embodiments. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. The accompanying drawings that form a part hereof, show by way of illustration, and not of limitation, specific embodiments in which the subject matter may be practiced. The embodiments illustrated are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed herein. Other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. Embodiments from one or more drawings may be combined with embodiments as illustrated in one or more different drawings. This Detailed Description, therefore, is not to be taken in a limiting sense, and the scope of various embodiments is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. [0093] While the foregoing disclosure shows a number of illustrative embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made herein without departing from the scope of the embodiments as defined by the appended claims. Accordingly, the disclosed embodiment are representative of the subject matter which is broadly contemplated by the embodiments, and the scope of the embodiments fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the embodiments is accordingly to be limited by nothing other than the appended claims. [0094] Moreover, ordinarily skilled artisans will appreciate that any illustrative logical blocks, modules, circuits, and process operations described herein may be implemented as electronic hardware, computer software, or combinations of both. [0095] To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and operations have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the embodiments. [0096] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the embodiments. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the embodiments. Thus, the embodiments are not intended to be limited to the embodiments shown herein but are to be accorded the widest scope consistent with the principles and novel features disclosed herein. [0097] The abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b), requiring an abstract that will allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. [0098] In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.

Methods are disclosed for a computational machine presentation including an origination point for a user, re-arranging a first selectable target more likely to be selected first, to a presentation nearer the origination point. The presentation format persists for any given user across a variety of computational machines, thus minimizing the effort for a given user in terms of cross computational-machine transfer and in terms of an on the average shortened navigational distance for any of the computational machines. The persistent format is consistent for cross computational-machine transfer, and this consistency coincides with a systematic decrease in navigational distance.

REFERENCE TO RELATED APPLICATIONS This is a continuation-in-part of U.S. patent application, Ser. No. 501,969, filed Aug. 30, 1974, now U.S. Pat. No. 3,897,950. BACKGROUND OF THE INVENTION The play of spiking is one of the most interesting in the game of volleyball and one for which volleyball players take great pleasure in establishing or setting and then completing. It involves more required coordination on the part of the spiking player than any other play in the sport and consequently is more difficult than any other play. Successful spiking requires that the ball be set, that is, lofted by a companion player into position such that it begins its descending arc almost vertically and in a position adjacent to the net and not over the net or accessible to defensive players. The spiker must be able to run or jump to meet the ball on its descending route, strike it while it is still above the level of the net and direct it over and downward into opposing territory. The play of spiking when being set up is obvious to the opposing team which allows them as players, to assume defensive positions. This makes the art of spiking even more difficult since the spiking player must not only coordinate his move with that of the set ball, but he must be able to watch opposing players, analyze their defense and spike to avoid them. Because the spiking step is one which involves a dynamic situation of both the ball and the spiking player as well as the defensive players, the training of spikers is difficult. Spiking defense, on the other hand, involves one or more players jumping at the appropriate time and location, and presenting a barrier with their open hands and arms. If successful, the defense players cause a rebound at high velocity and unpredictable direction. BRIEF STATEMENT OF THE INVENTION I have discovered that it is possible to segregate the separate steps in spiking and thereby facilitate the training of volleyball players. I have segregated the steps of the actual spike from that of playing the set through the use of a device including a support and a pair of arms at adjustable height above the ground level. The arms include flexible holders which cradle the volleyball at the correct position for the learning player to spike. The device is adjustable in height to teach the effects of the height of the ball at the time of the spike and also it is useful in teaching defensive players how to combat the spike. In its alternate embodiment, a substitute head for the spike training device is an array of spaced bars which, when struck with a spiked volleyball, will return the volleyball in an unpredictable direction and velocity depending upon its attitude when it is struck. This is comparable to the unpredictable nature of the block of a spike by a trained defensive player. It is adjustable in height and attitude as well. In a second alternate embodiment, the substitute head for the training device includes an array of spaced bars which extend in a vertical direction as opposed to a horizontal direction. Likewise, the frame member supporting the vertical bars is slightly concave in order to provide a limit for lateral return of the ball. BRIEF DESCRIPTION OF THE DRAWING This invention may be more clearly understood by the following detailed description and by reference to the drawings in which: FIG. 1 is a side elevational view of a spike training device in position for use; FIG. 2 is an enlarged fragmentary front elevational view of the ball holding head of this invention; FIG. 3 is a fragmentary vertical section to the support portion of the device of this invention; FIG. 4 is a perspective view of an alternate embodiment of this invention; FIG. 5 is a vertical section through the head of the embodiment of FIG. 4 taken along lines 5--5; FIG. 6 is a side elevational view of a variation of the embodiment of FIG. 4; FIG. 7 is a fragmentary sectional view of the apparatus of FIG. 6 taken along lines 7--7 of FIG. 6; and FIG. 8 is a fragmentary side elevational view of the apparatus of FIGS. 6 and 7; FIG. 9 is a perspective view of an alternate embodiment of this invention; FIG. 10 is a top plan view of the operating head of the embodiment of FIG. 9; FIG. 11 is a fragmentary top plan view of the embodiment of FIG. 9 shown in playing position; and FIG. 12 is an enlarged fragmentary sectional view along lines 12--12 of FIG. 9. DETAILED DESCRIPTION OF THE INVENTION As indicated above, the object of this invention is to place a volleyball in certain positions for the training of spiking and of the defense to spiking. In spike training the volleyball is positioned in the region of the net and at a selected height so that the player may have a virtually unobstructed view of the net, opposing players or defensive devices, and the ball, and be able to strike the ball without interference just as in the case of actual play. Each of these requirements are met by the device of FIG. 1. Now referring to FIG. 1, the volleyball training device includes a base 10 which may be merely the crutch tip type of base or, as shown in the drawing, a heavy base 10, sufficient to hold the device upright when in use. As is shown in the drawing, the base 10 is a hollow plastic body which may be filled with either sand or water to provide the necessary weight. It includes a recess 11 into which a support standard 12 is positioned. Extending in telescoping relationship with the support standard 12 is the operating head 13 which includes a pair of arms 14 and 15 having ball holders 16 and 20. The arm 15 is generally C shaped and constitutes an extension of the operating head 13 having sufficient height H and sufficient width W to provide a free clearance area for the player. Now referring to FIG. 2 for the details of the ball support 16 and 20 where they may be more clearly seen, the support members 16 and 20 are preferably of all foam plastic such as polystyrene having tapered inward extending faces, 30 and 31 respectively. The supports 16 and 20 are of sufficient length to telescope over the ends of the arms 14 and 15. Therefore the entire region adjacent to the ball 17 has a soft plastic consistency to protect the hands of the spiker. The tapered surfaces 30 and 31 cradle the ball 17 and release it upon being struck by the spiker's hand. I have found that the use of foam plastic effectively cradles the ball 17, and the spiker hardly detects any support, particularly at the moment of impact. This simulates as closely as possible the ball in free flight at the time of spiking. In accordance with this invention, the support 12 and operating head 13 are manufactured of anodized tubular aluminum. For example, its head exhibits a degree of flexibility and lightness in weight so that it may be easily moved and stored. In use, it is recommended that in addition to the support given by the base 10, a player hold the support standard 12 during use, to prevent overturning of the device in the event of a direct blow by an inexperienced player to the operating head. The holding person may well be trainer or coach who can readily observe at close hand the student spiker. I have found that the device, in accordance with this invention, must be light weight to afford easy handling and storage and the arms 14 and 15 must exhibit a degree of flexibility to allow easy movement of the ball 17 from its support 16 and 20 without interference with the direction or velocity of the spiked ball. This requirement of flexibility is achieved employing aluminum tubing as specified above. When subject to actual play, the points of greatest strain on the device are at the junction of the arms 14 and 15 in the operating head 13. I have found that the required flexibility in the operating head may be maintained while significant strength and resistance to permanent deformation or breakage may be accomplished in a manner as shown in FIG. 3. Now referring to FIG. 3, which is a sectional view at the intersection of the arms 14 and 15, the arm 14 is secured as by welding with the fillets apparent in the drawing. Within the tube 13, coextensive with the region of the intersection of arm 14 and 15, is an internal reinforcing tube 32 which is secured to the operating head 14 and arm 15 portion by a pair of machine bolts or other similar equivalent fasteners 33. In actuality, the stiffening member 32 and bolt 33 may also serve an additional function. That is that because of the size of the training device, it is sometimes desirable to segment it for storage. When such is the case, it is possible to have a seam between the arm 15 and the operating head 13 and between the bolts 33 and the stiffening member 32 which serves as an interconnecting member. In such case, the entire assembly may be reduced to approximately 1/3 of its maximum dimension as shown in FIG. 1. The principal purpose, however, of stiffening member 32 is to provide the strength for arms 14 and 15 while allowing the arms 14 and 15 per se to be flexible for light restraint on the ball 17. At the bottom of the operating head 13 there is a locking device of the twist lock type which allows the standard 12 and operating head 13 to be telescoped and locked at the appropriate height by twisting parts 12 and 13 with respect to each other. A particularly desirable lock for this purpose is illustrated in U.S. Pat. Nos. 3,095,825 and 3,515,418. Suffice it to say the lock 34 is effective to securely bind the operating head 13 to the standard 12 at any desired height ready for use as illustrated in FIG. 1. As indicated above, the training of a student spiker also allows the training of defensive players who position themselves on the opposite side of the net ready to attempt to block and return the spiked ball. When the defensive players are successful, the returned ball reflecting the high energy of a spiked ball and the closeness of the defensive players to the net allows the return ball to travel at high velocity in unpredictable direction. Incorporating the substitute head for the assembly of FIG. 1, the simulation of a return spike may be accomplished. This defensive training device appears in FIG. 4. Now, directing our attention to FIG. 4, you may see that the same base 10 in standard 12 is used, in this case, a substitute head 40 comparable to the operating head 13 portion of FIG. 1 being present. The operating head 40 includes a plurality of generally horizontally spaced bars 41 having a spacing therebetween less than the diameter of a volleyball. The use of spaced bars rather than a solid surface is truly significant to this invention. A simple reflective baffle board will serve to predictably return a ball. Players from the earliest ages have learned to detect that the angle of deflection of a ball striking a surface is approximately equal to the angle of incidence. Therefore, a truly representative condition cannot be achieved using a planar deflective surface. In this case, any spiked ball striking the device of FIG. 4 will strike either a single one of the bars 41, the upright 40 or its counterpart at the outer end 42. Striking a single or combination of the bars will result in a totally different direction of rebound. This is illustrated in FIGS. 6 and 7 showing an elevational view in FIG. 6 and a top view in FIG. 7. For example, if the operating bars 41 are in the exact vertical direction and the volleyball, as shown in FIG. 6, strikes midway between two adjacent bars, a direct return can be expected. However, any variation in the direction of incidence and the degree of impact on any one of the bars will unpredictably determine the rebound flight direction. This is true in both the vertical and horizontal planes. In the case of the rebound trainer of FIG. 4, the bars are all in fixed vertical arrangement. It has been found desirable, however, to change the angle of the array of bars 41. This is accomplished, as illustrated in FIGS. 6, 7 and 8, wherein the operating head 40 has an auxiliary member 40a, best seen in FIG. 8. The bars 41 are fixed to member 40a instead of head 40 and a sector vertical adjustment member 44 engages the operating head 40 and its adjustable counterpart 40a. Thus, by simply loosening a wing nut 45 and changing the angle of section 44, the entire array may be adjusted in angularity and the total effect of an impacting ball is changed. It is apparent that both training devices may be used simultaneously or separately and a single device with both the operating heads 13 and 40 may be used to alternately train spikers and defenders. Now referring to FIG. 9, one may see an alternate embodiment of this invention employing a similar base 10 with a single upright member 12 supported in opening 11 of the base 10 and supporting an operating head 50 which may be pivoted by hinge assembly 51 or may be a single rigid assembly. The operating head includes a lower bar 52 and an upper bar 53 joined by end bars 54 and 55. The upper and lower bars 53 and 52 may be either acute or angular with the angle or center of arc generally at a. Joining the upper and lower bars 53 and 52 are a number of intermediate bars 56. The vertical members may be variable in number and variable in spacing provided the spacing between adjacent members is less than the diameter of a volleyball. In the drawing as shown, there are five vertical members 56 between the ends of 54 and 55 and there are all shown in a vertical array. It may be recognized that by bending the assembly at the hinge 51, the angle of attack and return may be changed for the device and further, that the bars 56 need not all be parallel. One other feature which is apparent in FIG. 9 is that a single central support member is employed. This is, of course, an advantage over the embodiment of FIG. 4, where two supports are used with the resultant increase in total cost. Of additional significance is the fact that the embodiment of FIG. 9 is not planar but with the angle, tends to return balls into the playing area. The angular form appears in FIG. 10. Now referring to FIG. 10, the angularity of the operating head may be clearly seen. In the embodiment of FIG. 9, the device includes straight portions for the top and bottom members 53 and 52, of which top member 53 is visible and each side section 53a and 53b, offset by an angle A or B respectively. The angles A and B may be equal for a symetrical design or they may be different. I have found that the degree of angularity up to 20° is desirable to maintain the ball on the court, when in use, and also to provide a near reasonable simulation of actual play in spiking defense. This is particularly true since the spike defense player will not normally attempt to rebound the ball directly at the spiker, but to one side or the other. The typical play angles are illustrated in FIG. 11 where at the top the spiker has spiked direct onto the operating head 50 over the net 21. The rebound is at an angle with respect to the net. Below, in FIG. 11b, in the position shown similar to that of FIG. 11a, an angular rebound which more or less matches the angle of deviation of the head, provides a near direct rebound. It must be taken into account that in addition to the effect of the angle of the head, the principal factor in determining the angle of rebound of the ball is the uncontrolled and random relationship that occurs depending upon whether the ball strikes directly between two upright figure members 56 as illustrated in FIG. 12, or strikes one bar in 56 alone, or any other intermediate possibility. Therefore, the spiker cannot really predict where the return will be, adding to the effective training of the spiker. As is fairly apparent from a comparison of the blocking devices of FIG. 4 and FIG. 9, the device of FIG. 4 illustrated in FIG. 7, generally produces a return of the spike which deviates from the angle of incidence principally in the vertical plane, while the device of FIG. 9 provides principally lateral deviation. By periodic exchange of heads, the training of the spiker may be enhanced. Also, employing the embodiment of FIG. 9, the change of angularity by action at the hinge 51 enhances the vertical displacement on rebound. In each embodiment, the operation is significantly superior to any planar surface device. The above described embodiments of this invention are merely descriptive of its principles and are not to be considered limiting. The scope of this invention instead shall be determined from the scope of the following claims, including their equivalents.

A device for assisting in the training of volleyball players to learn the art and defense to the play known as spiking. This device is a holder for a volleyball at selected elevations near the volleyball net or a rebound surface. The holder allows a player to run, jump and strike the ball in a manner to drive it with great energy over the net and into opposing team's territory. The rebounder deflects a spiked ball in an unpredictable direction. The rebounder comprises a plurality of arms spaced less than a volleyball diameter apart and constituting an operating head. The operating head is positioned adjustably by a standard, whereby it may be located above and adjacent to a volleyball net to deflect unpredictably volleyballs spiked against it, for training of the defense to volleyball spiking.

CROSS REFERENCE OF RELATED APPLICATIONS [0001] Under 35 U.S.C. §119(e), this application claims priority of U.S. Provisional Patent Application Ser. No. 61/149,688 filed Feb. 3, 2009, entitled “LIGHTWEIGHT PINCH GRIP HANGER”, the disclosure of which is hereby incorporated by reference in its entirety for all purposes. BACKGROUND OF THE INVENTION [0002] 1. Field of Invention [0003] The present invention relates generally to molded plastic garment hangers as are widely used for the purpose of shipping and displaying garments. More specifically, the present invention relates to a lightweight pinch grip hanger with improved hanger body and pinch grips, which consumes less material and less energy for processing the material as compared to the prior art pinch grip hangers, while enhancing the pinch grip strength of the hanger, and without compromising the structural integrity and mechanical performance of the hanger. [0004] 2. Description of Related Art [0005] In the area of retail garment sales, so-called Garment-On-Hanger (GOH) programs have become preferred by retailers. In a GOH program, garments are delivered to retail merchants already suspended from hangers, where upon arrival at the retail location the garments are immediately placed on display for sale. Those hangers are normally plastic molded hangers as widely used for the purpose of shipping and displaying garments. [0006] In particular, different retailers have specified particular hangers or hanger characteristics among their several suppliers in order to achieve uniformity on their sales floors. To this end, industry standards as to hanger size, shape, performance characteristics, etc., are maintained, for example, by organizations such as the Voluntary Inter-industry Commerce Standards Association (VICS). [0007] With the continuing consumption of the natural resources, it is popular and necessary in the manufacturing industry, especially for mass production, to optimize the product design to save materials and energy and concomitantly reduce the manufacturing and transportation costs, without compromising performance. The resultant product under such a material and energy saving concept is recognized as an environmentally friendly product, and is much more market competitive than its prior art counterpart. Specifically, in the plastic hanger molding industry, millions of plastic hangers are manufactured each year. Thus, a lightweight pinch grip hanger, which consumes less material and less energy for processing the material compared to the prior art pinch grip hangers, greatly reduces manufacturing and transportation costs of a large amount of the hangers. Accordingly, the lightweight pinch grip hanger is environmentally advantageous, and also provides a significant commercial advantage to the manufacturer, transporter and retailer in the industry. [0008] It is desirable, however, that when a large amount of improved hangers, such as lightweight hangers, are transported and handled by the existing mechanical systems, these hangers do not conflict or interfere with the existing mechanical systems to adversely impact operability. [0009] Accordingly, there is a need for a novel pinch grip hanger that employs less material in manufacturing, reduces transportation costs and enhances the pinch grip strength of the hanger, while maintaining its structural integrity and mechanical performance to satisfy current industry standards, for example, the VICS standards. [0010] Accordingly, there is a need for a novel pinch grip hanger that is lightweight and easy to handle while enhancing the pinch grip strength and still maintaining the performance of the hanger. [0011] Accordingly, there is a need for a novel pinch grip hanger that effectively reduces manufacturing and transportation costs of the hanger, and uses less material to protect the environment. [0012] Accordingly, there is a need for a novel pinch grip hanger made from less material while enhancing the pinch grip strength and still maintaining performance and compatibility with the existing mechanical systems in the retailer facilities for transporting and handling hangers. BRIEF SUMMARY OF THE INVENTION [0013] Therefore, in order to overcome certain deficiencies of the prior art, provided according to the present invention is a lightweight pinch grip hanger. The pinch grip hanger includes a hook member and a body connected to the hook. The body includes a first arm extending from a centerline of the body to a first end of the body and a second arm extending from the centerline to a second end of the body. The hanger further includes a first pinch grip connected to the first end of the body, which includes a fixed jaw connected to the first end and a movable jaw mounted to the fixed jaw through a pivot shaft. The movable jaw includes an upper end which is moved toward an upper end of the fixed jaw when the movable jaw is actuated to open the pinch grip. The body further includes an upper flange, a lower flange and a connecting web between the upper flange and the lower flange. The first upper end of the movable jaw and the second upper end of the fixed jaw extend upwardly beyond the upper flange of the body. [0014] Preferably, the hanger body further includes an elevated portion formed substantially in the middle of the hanger body. [0015] Preferably, the pinch grip of the hanger is dimensioned to have a narrowed width relative to standard prior art pinch grip hangers. [0016] Preferably, the upper flange and lower flange of the hanger body are substantially horizontal and parallel to each other and the connecting web is substantially vertical to the upper and lower flanges. [0017] Preferably, the connecting web includes an upper straight portion, a lower straight portion, and a curved portion connecting the upper straight portion and the lower straight portion. [0018] Preferably, the first pinch grip includes a spring for applying a biasing force, against which the upper end of the moveable jaw and the upper end of the fixed jaw are moved toward each other to open the pinch grip. More preferably, the spring includes a cutout. [0019] Preferably, the hanger further includes a second pinch grip connected to the second end of the body. The second pinch grip includes a fixed jaw connected to the first end and a movable jaw mounted to the fixed jaw through a pivot shaft, the movable jaw comprising an upper end which is moved toward an upper end of the fixed jaw when the movable jaw is actuated to open the pinch grip. [0020] Preferably, the hanger further includes a supporting web integrally molded with the hanger body and the first pinch grip. More preferably, the hanger includes a first supporting web integrally molded with the hanger body and the first pinch grip and a second supporting web integrally molded with the hanger body and the second pinch grip. [0021] Preferably, the hanger body further includes a post extending upward from the body for receiving the hook member and a pair of reinforcing flanges disposed angularly between the post and the upper flange of the body. More preferably, the hanger further includes a size indicator operatively engaging the post and/or the reinforcing flanges to mount the indicator onto the hanger body, the size indicator capable of being actuated to release the engagement between the indicator and the hanger body. More preferably, the hanger further includes a size indicator operatively engaging the upper flange of the hanger body to mount the indicator onto the hanger body, the size indicator capable of being actuated to release the engagement between the indicator and the hanger body. [0022] Provided according to another aspect of the present invention is a pinch grip hanger. The hanger includes a hook member, a body connected to the hook, and an elevated portion arranged between the hook member and the body. The body includes a first arm extending to a first end of the body and a second arm extending oppositely to a second end of the body. The body further includes an upper flange and a lower flange connected by a middle web, the middle web including an upper straight portion, a lower straight portion and a curved portion between the upper straight portion and the lower straight portion. The hanger further includes a first pinch grip, having a first fixed jaw integrally molded to the first end of the body, a first movable jaw mounted to the first fixed jaw through a first pivot shaft, and a first biasing member against which the first movable jaw is actuated to selectively open the first pinch grip. The first fixed jaw includes an upper end positioned vertically above the upper flange of the body and the first moveable jaw includes an upper end positioned vertically above the upper flange of the body. The hanger further includes a second pinch grip, having a second fixed jaw integrally molded to the second end of the body, a second movable jaw mounted to the second fixed jaw through a second pivot shaft, and a second biasing member against which the second movable jaw is actuated to selectively open the second pinch grip. The second fixed jaw includes an upper end positioned vertically above the upper flange of the body and the second moveable jaw includes an upper end positioned vertically above the upper flange of the body. [0023] Provided according to another aspect of the present invention is a combination of hanger and size indicator. The combination includes a hanger and a size indicator. The hanger includes a hook member, a body connected to the hook, and a first pinch grip connected to the body. The body includes a first arm extending from a centerline of the body to a first end of the body and a second arm extending from the centerline to a second end of the body. The first pinch grip includes a fixed jaw connected to the first end and a movable jaw mounted to the fixed jaw through a pivot shaft. The movable jaw includes an upper end which is moved toward an upper end of the fixed jaw when the movable jaw is actuated to open the pinch grip. The body further includes an upper flange, a lower flange and a connecting web between the upper flange and the lower flange, and the upper end of the movable jaw and the upper end of the fixed jaw extend upwardly beyond the upper flange of the body. The body further includes a post extending upward from the body for receiving the hook member and a pair of reinforcing flanges disposed angularly between the post and the upper flange of the body. The size indicator operatively engages at least one of the post, the reinforcing flanges and the upper flange of the body, to mount the indicator onto the hanger body. The size indicator is capable of being actuated to release the engagement between the indicator and the hanger body. BRIEF DESCRIPTION OF THE DRAWINGS [0024] These and other features, aspects and benefits of the present invention will be made apparent with reference to the following specification and accompanying drawings, where like reference numerals refer to like features across the several views, and wherein: [0025] FIG. 1 is a prior art pinch grip hanger; [0026] FIG. 2 is a cross section view along line 2 - 2 in FIG. 1 , showing M section configuration of the prior art pinch grip hanger; [0027] FIG. 3 is an enlarged view of the prior art pinch grip hanger taken along the phantom line in FIG. 1 , showing the details of a pinch grip of the hanger; [0028] FIG. 4 is a front view showing a pinch grip hanger according to an exemplary embodiment of the present invention; [0029] FIG. 5 is a cross section view along line A-A in FIG. 4 , showing an I-beam section of the pinch grip hanger; [0030] FIG. 6 is a front view showing a pinch grip hanger according to another exemplary embodiment of the present invention; [0031] FIG. 6A is an enlarged view of a portion of the hanger in FIG. 6 ; [0032] FIG. 7 is a front view showing a pinch grip hanger according to another exemplary embodiment of the present invention; [0033] FIG. 8 is a front view showing a pinch grip hanger according to another exemplary embodiment of the present invention; and [0034] FIG. 9 is a cross section view along line B-B in FIG. 8 , showing a curved beam of the pinch grip hanger. DETAILED DESCRIPTION OF THE INVENTION [0035] Referring to FIG. 1 , illustrated is a pinch grip hanger 100 as is known in the art. The hanger has a hook member 110 and a hanger body 120 connected to the hook member 110 substantially at the middle of the body 120 . The hanger body 120 is substantially symmetrical along a centerline CL of the body, as shown in the figure. [0036] The body 120 has an upper portion, which includes a centrally located boss 130 , to which the hook member 110 is rotatably mounted. The boss 130 is reinforced by a pair of flanges 132 and 134 on opposite sides thereof, which are integrally molded and joined to a the body 120 . Preferably, the pair of flanges 132 and 134 are substantially symmetrical to one another relative to the centerline CL of the hanger body 120 . [0037] The region of the hanger, where the boss 130 and the flanges 132 and 134 are disposed and where the hook member 110 joins the hanger body 120 , is normally identified as a lower neck region of the hanger. The lower neck region can be used to attach an indicator for displaying information indicia with respect to the size, color and so on of the garments. [0038] The hook member 110 is preferably fabricated from wire stock and is connected to the hanger by insertion into the boss 130 . The removal of the metal hook member is prevented by any conventional attachment such as a threaded connection or an anchor clip. [0039] The hanger body 120 includes a first arm 140 extending from the centerline CL of the body 120 to a first end 142 of the body and a second arm 150 extending from the centerline CL of the body 120 to a second end 152 of the body. The first arm 140 and the second arm 150 are geometrically symmetrical to one another relative to the centerline CL and are integrally molded to provide a single piece hanger beam. The hanger 100 further includes a first pinch grip 160 integrally molded to the first end 142 and a second pinch grip 180 integrally molded to the second end 152 . The pinch grips can be actuated by a user to switch from a closed configuration to an open configuration for selectively holding a portion of a garment, which will be described later with reference to FIG. 3 . [0040] Referring to FIG. 2 , illustrated is a cross section view of the body 120 . The body 120 includes an upper flange 144 , a lower flange 146 and a web 148 for connecting the upper flange 144 and the lower flange 146 . The upper flange 144 and the lower flange 146 are substantially horizontal and parallel to one another. The web 148 connects the upper flange 144 and the lower flange 146 , thus to provide an M section configuration of the body 120 . [0041] Referring to FIG. 3 , illustrated is an enlarged view of the hanger 100 in the phantom line of FIG. 1 , showing the details of the pinch grip 160 and conjunction of the first pinch grip 160 with the hanger body 120 . [0042] The first pinch grip 160 includes a fixed jaw 162 integrally molded to the first end 142 of the hanger body 120 , a movable jaw 164 mounted to the fixed jaw 162 through a pivot shaft 166 . The movable jaw 164 includes an actuating portion 168 formed at the upper end 170 of the movable jaw 164 . The actuating portion 168 can be engaged by a user's finger to pivotally move the movable jaw 164 relative to the fixed jaw 162 around the pivot shaft 166 , against the biasing force applied by a spring 172 operatively mounted to the first pinch grip 160 . With the movement of the movable jaw 164 , the upper end 170 of the movable jaw 164 approaches the upper end 174 of the fixed jaw 162 , while the lower end 176 of the movable jaw 164 moves away from the lower end 178 of the fixed jaw 162 . Accordingly, the first pinch grip 160 switches from its closed configuration to its open configuration, to selectively hold a portion of a garment. [0043] As shown in FIG. 3 , the first pinch grip 160 has a first width W 1 , defined substantially from the left most point of the first pinch grip 160 to the right most point of the pinch grip 160 , and a first height H 1 , defined substantially from the upper most surface of the upper ends 170 and 174 to the lower most surface of the lower ends 176 and 178 . The hanger body 120 has a second height H 2 , defined substantially from the upper flange 144 to the lower flange 146 of the body 120 . [0044] Furthermore, the first pinch grip 160 is joined to the first end 142 of the hanger body 120 in such a manner that the upper end 170 of the movable jaw 164 and the upper end 174 of the fixed jaw 162 are in flush with the upper flange 144 of the hanger body 120 . In other words, the upper most surface of the upper end 170 , the upper most surface of the upper end 174 , and the surface of the upper flange 144 are substantially in a same horizontal plane. [0045] The configuration of the second pinch grip 180 is correspondingly similar. [0046] Referring again to FIG. 1 , the height of the hanger, from the upper most point of the hook member 110 to the lower flange 146 of the hanger body 120 , is shown as H A . [0047] Referring to FIG. 4 , illustrated is a lightweight pinch grip hanger according to an exemplary embodiment of the present invention, identified by numeral 200 . The hanger 200 includes a hook 220 and a body 240 connected to the hook 220 . Preferably, the body 240 is substantially symmetrical to a vertical centerline CL 1 of the hanger. [0048] The hanger 200 further includes a post 250 extending upward from the body 240 , the intersection of the post 250 and the body 240 defining a lower neck region of the hanger, where a lower neck sizer may be attached. The hook 220 is mounted to the post 250 through any known implement, such as mating threads. An example of the lower neck sizer can be found at U.S. Pat. No. 7,513,400 under the title “Spring Top Lower Neck Hanger Sizing” or U.S. Pat. No. 7,516,875 under the title “Lower Neck Indicator for Wire Hook Hanger”, which are commonly owned by the applicant of the present application. The entire disclosures of the above patents are incorporated by reference for all purposes. [0049] The hanger 200 further includes a pair of flanges 270 and 272 , disposed angularly between the post 250 and the body 240 , for reinforcing the post 250 . The reinforcing flanges 270 and 272 are disposed on opposite sides of the post 250 and are integrally molded to the body 240 and the post 250 . Preferably, the pair of flanges 270 and 272 substantially symmetrical to one another relative to the centerline CL 1 of the hanger body 240 . For example, the lower neck sizer operatively engages the post 250 and/or the flanges 270 and 272 , to mount the sizer onto the hanger. Alternatively, the lower neck sizer may engage an upper flange of the hanger body, which will be described later. Preferably, the indicator can be actuated to selectively release the engagement between the sizer and the hanger. [0050] The hanger body 240 includes a first arm 242 extending from the centerline CL 1 to a first end 244 of the hanger body 240 and a second arm 246 extending oppositely from the centerline CL 1 to a second end 248 of the hanger body 240 . [0051] Preferably, the first arm 242 and the second arm 246 are geometrically symmetrical to one another relative to the centerline CL 1 to provide a unitary single-piece hanger beam. A first pinch grip 280 is integrally molded to the first end 244 and a second pinch grip 290 is integrally molded to the second end 248 . Preferably, the pinch grips 280 and 290 can be actuated by a user or a machine to switch from a closed configuration to an open configuration for selectively holding at least a portion of a garment. [0052] FIG. 5 is a cross section view of the hanger body 240 . The body 240 includes an upper flange 241 , a lower flange 243 , and a connecting web 245 between the upper flange 241 and the lower flange 243 . Preferably, the upper flange 241 and the lower flange 243 are substantially horizontal and parallel to one another, and the connecting web 245 is substantially perpendicular to the upper flange 241 and the lower flange 243 . Accordingly, the hanger beam is substantially an I-beam. Alternatively, the web 245 can assume any other suitable shape, profile or position to provide an appropriate beam configuration for the hanger, such as a C-section beam. [0053] Referring back to FIG. 4 , the first pinch grip 280 includes a fixed jaw 282 integrally molded to the first end 244 of the first arm 242 , a movable jaw 283 mounted to the fixed jaw 282 through a pivot shaft 284 . The movable jaw 283 includes an actuating portion 285 formed at the upper end 286 of the movable jaw 283 . The actuating portion 285 can be engaged by a user's finger to pivotally move the movable jaw 283 relative to the fixed jaw 282 around the pivot shaft 284 , against the biasing force applied by a spring 288 operatively mounted to the first pinch grip 280 . [0054] With the movement of the movable jaw 283 , the upper end 286 of the movable jaw approaches the upper end 287 of the fixed jaw 282 , while the lower end of the movable jaw 283 moves away from the lower end of the fixed jaw 282 . Accordingly, the first pinch grip 280 switches from its closed configuration to its open configuration, to selectively hold a portion of a garment. [0055] Preferably, the lower end of the movable jaw 283 and the lower end of the fixed jaw 282 are formed with a plurality of teeth for enhancing the pinching and gripping capacity of the grip. Other gripping configurations known in the art including a long jaw with a single elongated tooth or a padded surface are also contemplated. [0056] Now referring to FIG. 5 , the hanger body 240 has a third height H 3 , defined substantially from the top of the upper flange 241 to the bottom of the lower flange 243 of the hanger body 240 . The third height H 3 is smaller than the second height H 2 of the standard prior art hanger 100 . Consequently, the resin material used for molding the hanger body 240 is reduced, compared to the prior art hanger 100 . Preferably, the ratio of the third height H 3 to the second height H 2 is approximately in the range of 40-90%. Accordingly, 10-60% less resin material is used for molding the hanger body 240 as compared to the material used for molding the hanger body 120 of the prior art hanger 100 . [0057] The upper end 286 of the movable jaw 283 and the upper end 287 of the fixed jaw 282 extend upwardly beyond the upper flange 241 of the hanger body 240 . In other words, either the upper end 286 or the upper end 287 is positioned substantially in a horizontal plane vertically above the horizontal plane in which the upper flange 241 resides. [0058] Furthermore, the inventor of the present invention has discovered that in such a configuration wherein the upper end 286 of the movable jaw 283 and the upper end 287 of the fixed jaw 282 extend upwardly beyond the upper flange 241 of the hanger body 240 , the leverage offered by the pinch grip is greater as compared to the prior art hanger 100 wherein the upper ends of the jaws of the pinch grip are flush with the upper flange of the hanger body. Accordingly, it is much more convenient for a user to operate the pinch grips of the hanger. The second pinch grip 290 is preferably structurally symmetrical to the first pinch grip 280 . In this regard, the pinch grip hanger 200 consumes less material by having a narrowed hanger beam, as well as shows a better performance for a user to operate the pinch grips. [0059] In addition, the pinch grips 280 and 290 , according to the embodiment of the present invention, are narrowed, having a narrowed width compared to the pinch grips of the standard prior art hanger, in order to further enhance the gripping capacity of the pinch grips. In this way, the same biasing force applied by the same spring is distributed along a shorter distance at the lower ends of fixed jaw and the moveable jaw, compared to the known pinch grips having a greater width. Thus, the unit gripping force of the fixed jaw and the moveable jaw of the present invention is higher than that of the prior art hanger. Accordingly, a further advantage, that the garments are reliably gripped by the pinch grips, can be provided. [0060] Specifically, as shown in FIG. 4 , taking the first pinch grip 280 as an example, the first pinch grip 280 has a second width W 2 , defined substantially from the left most point of the first pinch grip to the right most point of the first pinch grip. The second width W 2 is considerably smaller than the first width W 1 of the prior art hanger. Therefore, further material savings can be achieved by the slimmed pinch clip 280 , without compromising the mechanical performance of the hanger, in fact, enhancing the gripping capacity of the pinch grip. [0061] FIG. 6 illustrates a pinch grip hanger 300 according to another exemplary embodiment of the present invention. The hanger 300 includes a hook 320 and a body 340 connected to the hook 320 . Preferably, the body 340 is substantially symmetrical to a vertical centerline CL 2 of the hanger. [0062] The hanger 300 further includes a post 350 extending upward from the body 340 , the intersection of the post 350 and the body 340 defining a lower neck region of the hanger, where a lower neck sizer may be attached. The hook 320 is mounted to the post 350 through any known implement, such as mating threads. [0063] The hanger 300 further includes a pair of flanges 370 and 372 , disposed angularly between the post 350 and the body 340 , for reinforcing the post 350 . The reinforcing flanges 370 and 372 are disposed on opposite sides of the post 350 and are integrally molded to the body 340 and the post 350 . Preferably, the pair of flanges 370 and 372 are substantially symmetrical to one another relative to the centerline CL 2 of the hanger body 340 . [0064] The hanger body 340 includes a first arm 342 extending from the centerline CL 2 to a first end 344 of the hanger body 340 and a second arm 346 extending oppositely from the centerline CL 2 to a second end 348 of the hanger body 340 . Preferably, the first arm 342 and the second arm 346 are geometrically symmetrical to one another relative to the centerline CL 2 to provide a unitary single-piece hanger beam. A first pinch grip 360 is integrally molded to the first end 344 and a second pinch grip 380 is integrally molded to the second end 348 . [0065] The body 340 includes an upper flange 341 , a lower flange 343 , and a connecting web 345 between the upper flange 341 and the lower flange 343 . Preferably, the upper flange 341 and the lower flange 343 are substantially horizontal and parallel to one another, and the connecting web 345 is substantially perpendicular to the upper flange 341 and the lower flange 343 . Accordingly, the hanger beam is substantially an I-beam. Alternatively, the web 345 can assume any other suitable shape, profile or position to provide an appropriate beam configuration for the hanger, such as a C-section beam. [0066] The first pinch grip 360 includes a fixed jaw 362 integrally molded to the first end 344 of the first arm 342 , a movable jaw 363 mounted to the fixed jaw 362 through a pivot shaft 364 . The movable jaw 363 includes an actuating portion 365 formed at the upper end 366 of the movable jaw 363 . The actuating portion 365 can be engaged by a user's finger to pivotally move the movable jaw 363 relative to the fixed jaw 362 around the pivot shaft 364 , against the biasing force applied by a spring 368 operatively mounted to the first pinch grip 360 . [0067] With the movement of the movable jaw 363 , the upper end 366 of the movable jaw approaches the upper end 367 of the fixed jaw 362 , while the lower end of the movable jaw 363 moves away from the lower end of the fixed jaw 362 . Accordingly, the first pinch grip 360 switches from its closed configuration to its open configuration, to selectively hold at least a portion of a garment. Similar to the hanger body 240 of the previous embodiment, the hanger body 340 has a same height H 3 defined from the upper flange of the hanger body to the lower flange of the hanger body. [0068] Similarly, the second pinch grip 380 includes a fixed jaw 382 integrally molded to the second end 348 of the second arm 346 , a movable jaw 383 mounted to the fixed jaw 382 through a pivot shaft 384 . The movable jaw 383 includes an actuating portion 385 formed at the upper end 386 of the movable jaw 383 . The actuating portion 385 can be engaged by a user's finger to pivotally move the movable jaw 383 relative to the fixed jaw 382 around the pivot shaft 384 , against the biasing force applied by a spring 388 operatively mounted to the first pinch grip 380 . [0069] The hanger 300 further includes an elevated portion 390 continuous to the hanger body 340 , under the post 350 and the support flanges 370 and 372 . The elevation portion 390 is formed to implement a seamless interchangeability between the hangers according to the present invention and the prior art hangers. Thus, for existing mechanical systems in the retailer's facility for transporting and handling garments and hangers, such as suspension bars, racks and conveyers, the prior art hangers can be replaced by the hangers of the present invention, without causing any problem regarding the compatibility of the hangers with the conventional mechanical systems. Specifically, the distance between the suspension bar and the hanger body can be maintained. [0070] The elevated portion 390 includes an upper flange 392 and a pair of side flanges 394 and 396 . The pair of side flanges 394 and 396 are integrally molded to the upper flange 391 to provide a substantially trapezoidal or plateau shape of the elevated portion 390 with a continuous contour. Furthermore, the side flanges 394 and 396 are molded continuously and integrally with the upper flange of the hanger body 340 , and the elevation portion 390 is integrally molded with the hanger body 340 through a single molding process. Preferably, the elevated portion 390 is substantially symmetrical relative to the centerline CL 2 of the hanger body 340 . In the shown embodiment, the elevated portion 390 is substantially trapezoidal. However, it should be understood by a person of ordinary skill in the art that the elevated portion 390 can be of any suitable profile and shape. [0071] Referring to FIG. 6A , the elevated portion 390 has a fourth height H 4 defined substantially from the upper flange 392 of the elevated portion 390 to the upper flange of the hanger body 340 . Compared to the embodiment shown in FIGS. 4 and 5 , the elevation portion 390 of the hanger 300 vertically raises the hanger hook 310 and the post 350 . [0072] Thus, although the height H 3 of the hanger body 340 is smaller than the height H 2 of the hanger body 120 of the prior art hanger, the overall height H B of the hanger 300 , defined from the hook 320 to the lower flange of the hanger body 340 , is maintained substantially the same as the height H A of the prior art hanger 100 . [0073] Accordingly, the hangers of the present invention can be readily interchanged with the prior art hangers in a retailer's facility, to accommodate the existing garment/hanger conveying systems used in a Garment-On-Hanger system. [0074] Moreover, the height and the profile of the elevation portion 390 can be strategically adjusted, in association with the hook 310 , to further reduce the overall weight of the garment hanger 300 . [0075] For example, the height H 4 of the elevation portion 390 can be further extended, and the hook 310 can be shortened and minimized correspondingly. The extended height of elevation portion 390 compensates for the shortening of the hook 310 , which additionally reduces the overall weight of the hanger, while still maintaining the overall height of the hanger for the purpose of accommodating conventional hanger/garment conveying systems in the retailer's facility. [0076] FIG. 7 illustrates a pinch grip hanger 400 according to another exemplary embodiment of the present invention. The hanger 400 includes a hook 420 and a body 440 connected to the hook 420 . Preferably, the body 440 is substantially symmetrical to a vertical centerline CL 3 of the hanger. [0077] The hanger 400 further includes a post 450 extending upward from the body 440 , the intersection of the post 450 and the body 440 defining a lower neck region of the hanger, where a lower neck sizer may be attached. The hook 420 is mounted to the post 450 through any known implement, such as mating threads. [0078] The hanger 400 further includes a pair of flanges 470 and 472 , disposed angularly between the post 450 and the body 440 , for reinforcing the post 450 . The reinforcing flanges 470 and 472 are disposed on opposite sides of the post 450 and are integrally molded to the body 440 and the post 450 . Preferably, the pair of flanges 470 and 472 are substantially symmetrical to one another relative to the centerline CL 3 of the hanger body 440 . [0079] The hanger body 440 includes a first arm 442 extending from the centerline CL 3 to a first end 444 of the hanger body 440 and a second arm 446 extending oppositely from the centerline CL 3 to a second end 448 of the hanger body 440 . Preferably, the first arm 442 and the second arm 446 are geometrically symmetrical to one another relative to the centerline CL 3 to provide a unitary single-piece hanger beam. A first pinch grip 460 is integrally molded to the first end 444 and a second pinch grip 480 is integrally molded to the second end 448 . [0080] The body 440 includes an upper flange 441 , a lower flange 443 , and a connecting web 445 between the upper flange 441 and the lower flange 443 . Preferably, the upper flange 441 and the lower flange 443 are substantially horizontal and parallel to one another, and the connecting web 445 is substantially perpendicular to the upper flange 441 and the lower flange 443 . Accordingly, the hanger beam is substantially an I-beam. Alternatively, the web 445 can assume any other suitable shape, profile or position to provide an appropriate beam configuration for the hanger, such as a C-section beam. [0081] The first pinch grip 460 includes a fixed jaw 462 integrally molded to the first end 444 of the first arm 442 , a movable jaw 463 mounted to the fixed jaw 462 through a pivot shaft 464 . The movable jaw 463 includes an actuating portion 465 formed at the upper end 466 of the movable jaw 463 . The actuating portion 465 can be engaged by a user's finger to pivotally move the movable jaw 463 relative to the fixed jaw 462 around the pivot shaft 464 , against the biasing force applied by a spring 468 operatively mounted to the first pinch grip 460 . [0082] With the movement of the movable jaw 463 , the upper end 466 of the movable jaw approaches the upper end 467 of the fixed jaw 462 , while the lower end of the movable jaw 463 moves away from the lower end of the fixed jaw 462 . Accordingly, the first pinch grip 460 switches from its closed configuration to its open configuration, to selectively hold at least a portion of a garment. Similar to the hanger body 240 of the previous embodiment, the hanger body 440 has a same height H 3 defined from the upper flange of the hanger body to the lower flange of the hanger body. [0083] Similarly, the second pinch grip 480 includes a fixed jaw 482 integrally molded to the second end 448 of the second arm 446 , a movable jaw 483 mounted to the fixed jaw 482 through a pivot shaft 484 . The movable jaw 483 includes an actuating portion 485 formed at the upper end 486 of the movable jaw 483 . The actuating portion 485 can be engaged by a user's finger to pivotally move the movable jaw 483 relative to the fixed jaw 482 around the pivot shaft 484 , against the biasing force applied by a spring 488 operatively mounted to the first pinch grip 480 . [0084] In the embodiment, the hanger 400 further includes a pair of supporting webs 920 and 940 , positioned between the first end 444 and the fixed jaw 462 of the first pinch grip 460 and between the second end 448 and the fixed jaw 482 of the second pinch grip 480 , respectively. The supporting webs 920 and 940 structurally expand between the ends of the hanger body and the pinch grips. Specifically, the first supporting web 920 structurally connects the undersurface of the lower flange 443 , at the first end 444 , to the right lateral side of the fixed jaw 462 ; and the second supporting web 940 structurally connects the undersurface of the lower flange 443 , at the second end 448 , to the left lateral side of the fixed jaw 482 . Preferably, the supporting web 920 is integrally molded to the fixed jaw 462 of the first pinch grip 460 and the first end 444 of the hanger body 440 , and the supporting web 940 is integrally molded to the fixed jaw 482 of the second pinch grip 480 and the second end 448 of the hanger body 440 . [0085] The provision of the supporting webs effectively enhances the physical connection between the hanger beam and the pinch grips as well as the overall strength and integrity of the hanger body. Accordingly, the undesirable breaking off of the pinch grip is further prevented. [0086] In the shown embodiment, both supporting webs 920 and 940 are a thin layer of plastic material in the shape of substantial triangle with a curved underside. However, a person of ordinary skill in the art should appreciate that any other suitable shape and profile can be applied in place of or in addition to the shown structure. [0087] Furthermore, in the shown embodiment, the supporting webs 920 and 940 are both disposed under the lower flange 443 of the hanger body 440 , connecting the underside of the hanger body 440 with a lateral side of the fixed jaws of the pinch grips. Alternatively, the supporting webs 920 and 940 can be formed on the on the upper flange 441 of the hanger body 440 , connecting the upside of the hanger body 440 with a lateral side of the fixed jaws of the pinch grips. [0088] The hanger 400 further includes an elevated portion 490 continuous to the hanger body 440 , under the post 450 and the support flanges 470 and 472 . The elevation portion 490 is formed to implement a seamless interchangeability between the hangers according to the present invention and the prior art hangers. Thus, for existing mechanical systems in the retailer's facility for transporting and handling garments and hangers, such as suspension bars, racks and conveyers, the prior art hangers can be replaced by the hangers of the present invention, without causing any problem regarding the compatibility of the hangers with the conventional mechanical systems. Specifically, the distance between the suspension bar and the hanger body can be maintained. [0089] FIG. 8 illustrates a pinch grip hanger 500 according to another exemplary embodiment of the present invention. The hanger 500 includes a hook 520 and a body 540 connected to the hook 520 . Preferably, the body 540 is substantially symmetrical to a vertical centerline CL 4 of the hanger. [0090] The hanger 500 further includes a post 550 extending upward from the body 540 , the intersection of the post 550 and the body 540 defining a lower neck region of the hanger, where a lower neck sizer may be attached. The hook 520 is mounted to the post 550 through any known implement, such as mating threads. [0091] The hanger 500 further includes a pair of flanges 570 and 572 , disposed angularly between the post 550 and the body 540 , for reinforcing the post 550 . The reinforcing flanges 570 and 572 are disposed on opposite sides of the post 550 and are integrally molded to the body 540 and the post 550 . Preferably, the pair of flanges 570 and 572 substantially symmetrical to one another relative to the centerline CL 4 of the hanger body 540 . [0092] The hanger body 540 includes a first arm 542 extending from the centerline CL 4 to a first end 544 of the hanger body 540 and a second arm 546 extending oppositely from the centerline CL 4 to a second end 548 of the hanger body 540 . Preferably, the first arm 542 and the second arm 546 are geometrically symmetrical to one another relative to the centerline CL 4 to provide a unitary single-piece hanger beam. [0093] The hanger 500 includes a first pinch grip 560 connected to the first end 544 and a second pinch grip 580 integrally molded to the second end 548 . The first pinch grip 560 includes a fixed jaw 562 integrally molded to the first end 544 of the first arm 542 and a movable jaw 563 mounted to the fixed jaw 562 through a pivot shaft 564 . The movable jaw 563 includes an actuating portion 565 formed at the upper end 566 of the movable jaw 563 . The actuating portion 565 can be engaged by a user's finger to pivotally move the movable jaw 563 relative to the fixed jaw 562 around the pivot shaft 564 , against the biasing force applied by a spring 568 operatively mounted to the first pinch grip 560 . [0094] With the movement of the movable jaw 563 , the upper end 566 of the movable jaw approaches the upper end 567 of the fixed jaw 562 , while the lower end of the movable jaw 563 moves away from the lower end of the fixed jaw 562 . Accordingly, the first pinch grip 560 switches from its closed configuration to its open configuration, to selectively hold at least a portion of a garment. The second pinch grip 580 has same or similar structures. [0095] The hanger 500 further includes an elevated portion 590 continuous to the hanger body 540 , under the post 550 and the support flanges 570 and 572 . The elevation portion 590 is similar to the elevation portion 390 of the hanger 300 . [0096] FIG. 9 is a cross section view of the hanger body 540 , along the sectional lines B-B in FIG. 8 . The body 540 includes an upper flange 541 , a lower flange 543 , and a connecting web 545 between the upper flange 541 and the lower flange 543 . [0097] Preferably, the upper flange 541 and the lower flange 543 are substantially horizontal and parallel to one another. In this exemplary embodiment, the connecting web 545 includes an upper straight portion 546 , a lower straight portion 547 and a middle curved portion 548 between the upper straight portion 546 and the lower straight portion 547 . Accordingly, viewed from the side, the hanger beam has a raised membrane from the plane of the vertical part of the hanger beam, as shown in FIG. 9 . The rippled configuration of the hanger beam significantly improves the rigidity of the hanger beam. Preferably, the curved portion 548 extends through the overall length of the hanger body 540 . [0098] Although only one curved portion 448 is shown in the figure, it should be understood by a person of ordinary skill in the art that a plurality of curved portions can be formed, raising from either side of the hanger beam. [0099] Similar to the hanger body 240 and 340 of the previous embodiments, the hanger body 540 has a same height H 3 defined from the upper flange 541 of the hanger body 540 to the lower flange 543 of the hanger body 540 , such that the hanger 500 can readily replace a prior art hanger in a Garment-On-Hanger system, without causing any conflict or interference with the existing bars, racks and conveyers of the retailer's facility. [0100] The inventor of the present invention has conducted a comparison experiment for assessing the resin material saved by an example of the novel configuration of the pinch grip hanger according to the present invention. [0101] Following Table 1 presents the comparison of the parameters of the hanger according to the present invention vis-à-vis the parameters of a market-accessible prior art hanger (such as a “6012/12” pinch grip hanger according to VICS), both hangers meeting the requirements of the acknowledged industry standards, such as the VICS standards. [0000] TABLE 1 Prior Art Pinch Grip Pinch Grip Hanger of the Hanger (having Present Invention (having Parameters an I beam) an I beam) Height of I beam 0.75″ 0.50″ Width of I beam 0.30″ 0.30″ Height/width ratio of I beam 2.5  1.67  Weight of metal hook 8.0 g 8.0 g Weight of metal springs 5.0 g 5.0 g Weight of K resin of hanger 23.6 g 20.0 g body Weight of K resin of clips 7.5 g 6.2 g Total weight of K resin of 31.1 g 26.2 g hanger Total weight of hanger 44.1 g 39.2 g [0102] It can be concluded from the Table 1 that, compared to the prior art hanger averagely consuming 31.1 g of K resin, the hanger according to the present invention consumes 26.2 g of K resin. In other words, 4.9 g of K resin are saved per hanger, which accounts for about 15.75% of the total resin material of the prior art hanger. With significantly less resin material consumed, the mechanical performances of the hanger according to the present invention are still maintained at a level same or even superior than that of the prior art hanger. [0103] Each year, about 750 million pinch grip hangers are manufactured in accordance with the VICS standards. Thus, the pinch grip hanger according to the present invention would reduce the K resin material by about 8.1 million pounds annually, which would eliminate about 24.0 million pounds of CO 2 emission for producing the same amount of K resin. Furthermore, the reduction of resin material leads to less consumption of energy and resources for storing, transporting and handling the hangers. Hence, the pinch grip hanger according to the present invention helps to preserve environment and resources, while still providing improved products to the consumers. [0104] The hanger of the present invention can be formed of one or more of polystyrene, SAN, ABS, PPO, nylon, polypropylene (PP), polyethylene, PET, polycarbonates (PC), acrylics, K-resin, and polyvinyl chloride (PVC) among others. [0105] From the foregoing illustrations it is readily apparent that the present invention is directed to a lightweight molded plastic garment hanger for high volume injection molding. According to the shown embodiments of the present invention, the resin material for molding the hanger body can be significantly reduced, and concomitantly the manufacturing cost and transportation cost of the hangers can be significantly reduced, while maintaining the strength, integrity and performance of the hanger. Consequently, the pinch grip hanger according to the present invention can offer the manufacturers, transporters and retailers of the hangers a market advantage, which cannot be offered by the traditional pinch grip hanger. [0106] The hangers of the present invention consume less material while still maintaining the mechanical performance under industry standards, for example, the VICS standards. Moreover, the production of such hangers is environmentally advantageous. [0107] The present invention has been described with respect to certain exemplary embodiments. Certain alterations and/or modifications will be apparent to those skilled in the art, in light of the instant disclosure, without departing from the spirit or the scope of the invention. These embodiments are offered as merely illustrative, and not limiting, on the scope of the invention, which is defined solely with reference to the following appended claims.

In a lightweight and environmentally friendly pinch grip hanger, the height of the hanger body is reduced to have the upper ends of the jaws of the pinch grip to extend beyond the upper flange of the hanger body. This configuration reduces the weight of the hanger and saves the raw material used to mold the hanger. The hanger is environmentally friendly. The hanger further has an elevated portion formed below a lower neck region of the hanger where the hook of the hanger mounted to the hanger body. The hanger body further has a raised rib extending throughout the entire length of the hanger body.

BACKGROUND OF THE INVENTION 1. Technical Field The present invention relates to a method for making a pita chip or crisp and other such products in a continuous sheeting operation. Specifically, the process involves cutting a sheeted dough into longitudinal strips, cooking these longitudinal strips to form tubes, and pressing these tubes with a nub press prior to cutting and finish cooking. 2. Description of Related Art Pita bread is a type of flatbread typically a round pocket bread, believed to have originated in the Middle East. The baking process typically involves forming, by rolling, a flat dough disk that is baked in a hot oven, usually in excess of 500° F., on a flat support surface. The “pocket” inside the finished loaf is created during cooking when the outside layers of the bread are seared, thus forming a cap that impedes the release of steam from the interior of the bread. This trapped steam puffs up the dough in the middle of the bread forming a pocket. As the bread cools and flattens, a pocket is left in the middle that can be later stuffed for making sandwiches and the like. Pita “chips” or “crisps” (these two terms are used interchangeably herein) can be made by cutting or chopping pita bread loaves into chip sized pieces. Making individual round pita bread loaves and cutting each loaf into chip sized pieces can be time consuming and is not conducive to an efficient, continuous operation. One prior art approach to this issue involves pressing a dough ball between two hot plates to form the pita loaf and then cutting the loaf into smaller chip sizes. This approach is referred to as a dough ball press method followed by chopping of the bread loaves. The dough ball press method is not particularly efficient and has not demonstrated desirable throughput rates on continuous or semi-continuous product lines. One attempt at developing a continuous process that makes pita chips or crisps more efficiently than the dough ball press method can be found in U.S. Pat. No. 6,291,002 entitled “Method for Preparing Elongated Pita Bread” issued on Sep. 18, 2001, to inventor George Goglanian (the “Goglanian Patent”). The Goglanian Patent describes a process whereby dough is sheeted and then cut longitudinally into continuous strips. These strips are run through an oven, thereby producing a tube-shaped bread product. A tube shape, however, is not conducive to making into a flat chip, because cutting the resultant tube would yield shorter tube segments as opposed to flat chips. Consequently, the Goglanian Patent teaches cutting this tube along its longitudinal edges into two sections, a top section and a bottom section. When these sections are cut into chip shapes, the sections fall away from each other, thus making chips of both the top and the bottom of the tube. The process described in the Goglanian Patent produces a pita chip or crisp with only one side having the characteristic pita bread exterior texture. The other side of the chip comprises the interior of the cooked tube and, therefore, presents a different texture than the outside surface. Further the Goglanian Patent requires the cutting step that separates the top half of the tube from the bottom half of the tube. This step requires special cutting equipment and leads to product loss during the cutting itself. While the Goglanian Patent can produce a chip from flatbread, it does not produce the pita chip similar to one made by chopping or cutting a round pita bread loaf. Consequently, a need exists for a continuous pita chip process, along with the accompanying equipment, that can efficiently produce a pita chip having the exterior pita texture on both sides of the chip such that it resembles a pita chip made by cutting a traditional pita bread loaf. Such process should be capable of throughput rates typical of sheeter lines and, preferably, use equipment which provides for a minimal plant footprint. SUMMARY OF THE INVENTION In a preferred embodiment the invention mixes raw ingredients to produce a sheetable dough. In one embodiment, the dough is then subjected to a low stress sheeting step followed by a proofing step. After the dough is proofed it is cut, for example into longitudinal strips, and then proceeds continuously to a pita oven for cooking. Shortly after exiting the oven the cooked dough, now in a tube shape, is run through a nub press, which in a preferred embodiment is a pin roller. After this pressing step, the product is allowed to cool, is cut into chip shaped pieces, and is further cooked and seasoned prior to packaging. The invention provides for a continuous process that produces a pita chip or crisp that resembles a pita chip made by cutting a traditional pita bread loaf into chips. Yet, such process provides for substantially increased throughput and minimal plant footprint. BRIEF DESCRIPTION OF THE DRAWINGS The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred embodiment, further objectives and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein: FIG. 1 is flowchart of Applicants' method for making pita chips; FIG. 2 illustrates cooked dough tubes exiting a pita oven as a part of Applicants' method; FIG. 3 is a perspective view of a portion of one of the dough tubes of FIG. 2 ; FIG. 4 is a perspective view of a chip produced by Applicants' invention; FIG. 5 is a schematic of one embodiment of Applicants' oven and press combination; and FIGS. 6 a , 6 b , and 6 c illustrate a preferred embodiment nub press pin roller of Applicants' invention. DETAILED DESCRIPTION Referring to FIG. 1 , Applicants' process starts with sheeting of a dough during a sheeting step 102 . In a preferred embodiment, this sheeting step 102 is a low-stress sheeting operation, typically involving two or more sheeter roller pairs, such that the thickness of the sheet is gradually reduced, thereby limiting the work imparted to the dough by the sheeters. In one embodiment, the dough sheet is sheeted 102 to a final thickness of approximately 0.0625 ( 1/16) inches to 0.1875 ( 3/16) inches. This dough sheet then continues down a conveyor system through a proofing step 104 , typically involving a proofer box or proofer. A proofer is a type of food processing equipment that allows the dough to rise in a relatively warm and humid environment for a period of time before further processing. Proofing relaxes the stress in the dough and lets the yeast work. A proofer box is a chamber that is humidity and temperature controlled, for example at around 90° F. and about 50% relative humidity. The proofing time using Applicants' invention varies between zero minutes to twenty minutes, depending upon the amount of flour in the dough, the amount of yeast in the dough, and the preferred texture of the end product. For example, a softer textured product requires a longer proofing time than a harder textured product. After exiting the proofer at the proofing step 104 , the dough continues down a conveyor through a continuous cutter at a cutting step 106 . In a preferred embodiment, this cutter cuts the dough into continuous longitudinal flat strips. However, the cutter can also make shapes other than longitudinal flat strips, such as longitudinal hexagonal shapes and longitudinal round shapes. In an alternative embodiment, the cutting step 106 can occur prior to the proofing step 104 . The continuous longitudinal strips formed by the cutting step 106 continue along a conveyor and are spread apart by a spreading conveyor in order to input small gaps between the strips prior to entering a continuous pita oven where it is cooked during a cooking step 108 . These small gaps assure that the strip doesn't join back together during cooking 108 . In a preferred embodiment, the pita oven is a two zone oven set at 850° F. and 575° F. for zones 1 and 2, respectively, for a dwell time, in a preferred embodiment, of between six and thirty seconds, depending on product thickness and heat intensity. During this cooking step 108 , the longitudinal strips puff up, thereby forming a cavity in the center of each strip, as can be seen in FIG. 3 , resulting in tube-like longitudinal strips (or hollow ropes) exiting the pita oven, as can be seen in FIG. 2 . Returning to FIG. 1 , after the cooking step 108 , these longitudinal tubes can be subjected to an optional cooling step 110 varying from zero seconds to fifteen seconds depending on the line speed required to achieve the desired texture and shape of the end product. For example, eliminating the cooling step 110 results in a harder product than conducting a cooling step 110 of up to fifteen seconds. After the cooling step 110 , the longitudinal tubes are subjected to a pressing step 112 . In a preferred embodiment, this involves a nub press or pin roller, as will be described in more detail in reference to FIGS. 6 a , 6 b , and 6 c . This pin roller presses the interior surfaces of the tube together. Because this pressing step 112 occurs very shortly after the cooking step 108 , the dough inside the longitudinal tube is still somewhat pliable and tacky. Consequently, the pressing step 112 generally flattens the tube such that the inner surfaces of the pocket adhere in places, thereby forming a relatively flat, double layered product resembling a standard pita flatbread in its cross-section, but without the completely open pocket. After the pressing step 112 this now generally flattened longitudinal strip is subjected to a second cooling step 114 that varies in time from zero to thirty seconds, depending on the cooling conditions and desired end product, prior to cutting into snack size pieces. If a single layered pita chip resembling that described in relation to the Goglanian Patent is desired, the flattened tube is next subjected to a splitting step 116 . This splitting step 116 separates the flattened tube into a top and bottom strip. This step 116 is listed as optional, as the preferred embodiment maintains the upper and lower portions in contact to thus later form a food piece having two layers. The flattened longitudinal strip is next cut in a cutting step 118 by, for example, a cutting roller that forms individual chip-sized pieces, such as is illustrated in reference to FIG. 4 . Finally, and again in reference to FIG. 1 , these individual pieces are finish cooked and seasoned 120 prior to packaging. Each of the individual steps described in general with reference to FIG. 1 will now be described in more specific detail in relation to a preferred embodiment of Applicants' invention. Table 1 below shows the dough formula used to produce a pita chip in accordance with this preferred embodiment. TABLE 1 Ingredient Weight Percentage Wheat Flour 30-62 Whole Wheat Flour  0-31 White Whole Wheat Flour 1-2 Sugar 1-2 Salt 0-2 Oat Fiber 0-1 Yeast 1 Actual water 32-34 The raw ingredients listed in Table 1 are first fixed mixed to hydration in order to form a pliable dough. This can be done, for example, by a triple roller horizontal bar mixer. A typical mix time is between two and six minutes to a dough temperature of about 82° F. to 90° F. Once the dough is formed, it is fed into a sheeter. The preferred sheeter utilizes three sets of sheeting rollers in order to progressively sheet 102 to a thinner sheet thickness while imparting a minimum amount of work into the dough during the process. A final sheet thickness of between 1/16 inch and 3/16 inch is preferred given the ingredients for the dough listed in Table 1. The proofing step 104 is a continuous step that mimics the static resting of the dough in an environment with a constant temperature and humidity. This is accomplished by the use of a proofer box such as a continuous proofer with humidity and temperature control, which is a cascading multi-tier proofer designed to process a continuous dough sheet. Preferably, the proofer box used with Applicants' invention is maintained at a temperature of between 75° F. and 95° F. and a humidity level of between 45% and 65%. More preferably, the temperature inside the proofer is about 85° F. and about 55% humidity. The dwell time during the proofing step 106 is adjusted depending on the composition of the dough admix and the preferred texture of the end product. In relation to the dough composition disclosed in FIG. 1 , the dwell time in the proofer preferably ranges between one minute and fifteen minutes. Applicants most preferred embodiment using the dough described in Table 1 involves a proofing step at 85° F. and 55% humidity for a period of about eight minutes. After exiting the proofer, the dough is subjected to a cutting step 106 , preferably cut into longitudinal strips that are 1.25 inches wide. As noted previously, the cutting step 106 can optionally occur prior to the proofing step 104 . After the cutting 106 , the longitudinal strips are slightly separated by a spreading conveyor in order to maintain some distance between each longitudinal strip as they proceed through the next step, the cooking step 108 . A gap of 0.125 inches is accomplished by the spreading conveyor in a preferred embodiment, but other distances are acceptable as long as the strips are not touching each other at their lateral edges. Referring again to the dough made by the ingredients listed in Table 1, Applicants' preferred embodiment involves a continuous infrared oven with radiant, connective and conductive heat from both the top and bottom sides of the product conveyor. It is preferred to subject the dough made by the ingredients of Table 1 to a temperature of greater than 500° F. for a dwell time during the cooking step 108 of less than one minute. Doing so sears the exterior of the longitudinal dough strips causing capping layers on the exterior of the strips and a continuous cavity to form inside the strips. This makes the dough strips into partially-cooked bread tubes or hollow ropes. This can best be understood with reference to FIGS. 2 and 3 . In a preferred embodiment a two zone oven is used with temperature settings of 850° F. and 575° F. in zones 1 and 2, respectively, for a dwell time of between ten and fifteen seconds or, more preferably, about 12.7 seconds. It should be noted that the cooking step 108 is only a partial cooking of the dough. In a preferred embodiment, the dough enters the oven at 42% water by weight and exits the oven at 32% water by weight, thereby reducing the moisture level of the dough during the cooking step 108 by less than 11%. The strips as they exit the oven are still pliable and somewhat tacky on the inside. Referring to FIG. 2 , several of these bread tubes 220 are shown exiting the oven 250 immediately after the cooking step by way of a conveyor 252 . A perspective view of a cross-sectional portion of one of these tubes 220 is shown in FIG. 3 as a tube piece 320 . By viewing the piece 320 in cross-section, it can be seen that a cavity has formed between the upper layer 322 and the lower layer 324 . Also shown is one of the lateral edges 326 . Returning to FIG. 1 , Applicants' method can incorporate an optional cooling step 110 depending on the environmental temperature and line speed. If a tube 220 is pressed together while the product is too hot, the interior cavity can be joined back together, so to speak, making the finished product harder. The cooler the product before pressing, the less bonding spots and the softer the finished product. It should be noted that the cooling step 110 is, in any event, relatively short such that the partially cooked bread tubes are not allowed to set up or harden in the shape illustrated by both FIGS. 2 and 3 . Instead, the tubes are either immediately or within a short period of time after the cooking step 108 , and certainly no more than 15 seconds thereafter, subjected to the pressing step 112 . It is preferred that the internal temperature of the dough tube at the time of the pressing step 112 should be at least 140° F. and preferably of between 140° F. and 210° F. The purpose of this pressing step 112 is to collapse the tube and reform these continuous ropes into flat longitudinal strips. This is accomplished, in a preferred embodiment, by a device referred to as a nub press or pin roller. A nub press is a flat plate having protrusions or nubs that is periodically pressed onto the passing partially cooked bread tubes. A more preferable embodiment uses a pin roller such as illustrated in FIG. 6 . A pin roller is a cylindrical roller with protruding pins. Ideally, and as it is illustrated in FIG. 5 , this pin roller 562 is located in close proximity to the exit of the pita oven 550 such that the bread ropes or tubes that exit the oven 550 on the conveyor belt 552 are shortly thereafter subjected to the previously described pressing step. This pressing step, in a preferred embodiment, occurs continuously with the tubes proceeding along the conveyor 522 to be pressed between the pin roller 562 and a support plate 564 . Thereafter, the flattened strips continue along the direction indicated on the conveyor 552 to the next processing step. Referring now to FIGS. 6 a , 6 b , and 6 c , a pin roller 662 is illustrated. FIG. 6 a shows a perspective view in elevation of the pin roller 662 . The pin roller 662 is mounted on a shaft 670 . The pin roller 662 consists of a curved surface interspersed with raised pins 682 . The pin roller 662 illustrated has an overall tube length 672 of 20.0 inches or 508 mm. Referring to FIG. 6 b , which is a side view of the pin roller 662 mounted on the shaft 670 , the height or outside diameter 676 of the tube 662 (not taking into account the pins 682 ) is 5.229 inches or 133 mm. Taking into account the pins 682 , the over diameter 674 of the pin roller 662 is 5.729 inches or 146 mm. In the embodiment illustrated, the height of each individual pin 682 from the tube surface of the pin roller 662 is 0.250 inches or about 6 mm. Further, the roller is spaced from the conveyor surface such that the end of the pins 682 are 1/16 inch away from the conveyor surface at the closest point. FIG. 6 c is a cut away section of the pin roller surface flattened in order to illustrate the relative distance between the pins 682 and the pattern used. It can be seen that the pins 682 are arranged in a triangular pattern resulting in a series of vertical and horizontal rows. FIG. 6 c is oriented such that the horizontal rows of pins 682 are parallel to the shaft 670 and the vertical row of pins 682 are perpendicular to the shaft 670 . The vertical distance 688 between pins 682 in vertical rows is 1.0 inches or 25 mm, while the vertical distance 680 as between pins 682 in adjacent vertical rows is 0.50 inches or 13 mm. The horizontal distance 684 between adjacent vertical rows is 0.866 inches or 22 mm, while the horizontal distance 686 between two vertical rows separated by a third vertical row is 1.7320 inches or 44 mm. The roller 662 depicted, therefore, is 23 pins wide and 18 pins around. Each pin 682 has a spherical radius of 0.188 inches. The pins 682 illustrated in FIGS. 6 a , 6 b , and 6 c provide for points of increased pressure along the bread tube during the pressing step. For a dough thickness out of the sheeter of about 3/32 inch, a press gap of 1/16 inch is preferred in order to impart the desired structure for a pita chip end product. The pressing with a nub press or pin roller of such configuration is preferable because it allows for a continuous process, providing controlled contact or press points without completely flattening the strips, which in turn contributes to the textural characteristics of the end product. The triangular pattern center of 1 inch is optimized for the thickness of the product to manage the span between the attachment points to minimize breakage. This varies depending on product thickness and strength. Returning again to FIG. 1 , after the pressing step 112 is accomplished, the now flattened and partially cooked strips continue along a conveyor and are allowed to cool, typically in ambient conditions, for between 12 minutes and 20 minutes. Referring again to the dough formulation listed in Table 1, is it preferable for the formation of a pita chip that the dough be allowed to cool at this cooling step 114 for approximately 15 minutes. If it is desirable to produce a pita chip wherein one side of the chip is characteristic of the outside surface of a pita and the other side of the chip is characteristic of the inside surface of the pita pocket, Applicants' invention can optionally employ a splitting step 116 that involves splitting the piece along its lateral edges. This can be done, by example, with a modified band saw typically used for cutting bread. In a preferred embodiment, however, the flattened strips proceed to a cutting step 118 , typically involving a cutting roller, that can cut the strips into chip sized shapes, such as rectangular shapes or triangular shapes. A rectangular shaped chip is illustrated in FIG. 4 , which shows a pita chip 420 with an upper surface 422 , a lower surface 424 , and two lateral edges 426 , 428 . It can be seen that this end product 420 exhibits an undulating exterior surface. The interior surface also maintains variations in the distance between the two distinct layers of the chip 120 produced by the process, such that in places the layers are physically connected and in other are separated slightly by small pockets of between 0.5 mm and 2.0 mm in height, for example. After cutting the strips to form the chips 420 shown in FIG. 4 , the chips 420 are finished cooked and seasoned. This finish cooking can involve convection baking, hot air drying, microwave cooking, frying, or other finish cook methods known in the art in order to lower the end product moisture level to a desired end point. In a preferred embodiment, the moisture level is lowered to between 3% and 1% by weight. Thereafter, the finished product is packaged by methods known in the art. Table 2 below shows the composition of a finished product in accordance with one embodiment of Applicants' invention. The ingredients are listed by weight percentage of the finished crisp. TABLE 2 Finished Product Composition Percentage Wheat Flour 73.3 Salt 2.4 Sugar 1.8 Yeast 2.8 Oat Fiber 0.9 Vegetable Oil 17.4 Water 1.4 It should be noted that the entire process described as Applicants' preferred embodiment involves the continuous movement of the dough or product starting from the sheeting step through the finish cooking and seasoning step. The process is intended to take place using conveyors along with equipment that accommodates the continuous operation of each of the steps described. This allows for the continuous production of a flat bread type product without the need for the use of the dough ball and hot press equipment used in prior art. Equipment used in this continuous process is said to be ‘in communication,” because dough and/or product moves continuously from one piece of equipment (such as sheeter, proofer, oven, press, etc.) to the next piece of equipment. Further, while Applicants' invention has been described with reference to a pita chip embodiment, the processing steps and equipment used with Applicants' invention and described herein are equally adaptable for producing any number of types of flat bread products on a continuous processing line, including crackers. Adjustments can be made to the initial dough composition and various processing parameters, including cooling times, oven temperatures, dwell times at various stages, and temperature and humidity during the proofing stage, to produce flat bread products of varying types and consistencies. For example, a differential speed in conveyors of 2:1 can be used between the proofing step and oven to create a cracker like texture in the final product by stretching the dough before cooking. It should be understood that Applicants' invention can substitute for the prior art dough ball and hot press method and equipment in order to produce any type of flat bread, such as the East Indian Naan bread, previously made by prior art methods but with the efficiencies and throughput of a continuous process. While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

A continuous process for making a pita chip or other similar products using a continuous pressing step that occurs shortly after a continuous oven initial cooking step. Applicants' invention produces a final product with characteristics of a traditionally cooked pita chip using equipment that provides for significant increases in manufacturing throughput. The use of a continuous oven with the relatively concurrent pressing step allows for the production of a flat chip piece on a continuous product line.

BACKGROUND OF THE INVENTION Repair clamps for repairing leaks in pipes are well-known and widely used. Generally these clamps have a gasket overlain with a metal band encircling the pipe. These bands may be in the form of two half-circles, or a single full circle having a pair of flanges at the longitudinal joint. Bolt and nut assemblies usually connect these flanges and are tightened to draw the band (and the gasket) about the pipe over the leak. In the case of lines which are usually below ground, after excavating for a working area around the leak, the leaking fluid tends to collect in the area, making working conditions hazardous as well as unpleasant. As stated above, the present method of installing the repair clamp includes tightening the nuts on the bolts with a socket wrench or the like. This is relatively time-consuming. SUMMARY OF THE INVENTION It is accordingly a primary object of this invention to provide a tool for drawing together the flanges of a repair clamp in a rapid manner, and providing a tight shut-off while the clamp bolt-and-nut assemblies are being drawn up. It is another important object of this invention to provide two lever systems in a tool, one for rapid closure while the resistance is relatively low, and a second for exerting considerably greater closing force. It is another object of this invention to provide a method of rapidly and positively shutting off a leak from a fluid-filled pipe using a repair clamp assembly and the tool of the instant invention. The instant invention is a compound tool designed for particular use with repair clamps useful in sealing leaks in fluid pipe lines, but also finding utility in other areas where spaced flanges are to be brought closer together. One prior art patent, U.S. Pat. No. 3,108,783, solves a portion of this problem in a very limited fashion, but does not envision anything like the solution presented herein. The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. Also, a method of applying a repair clamp to a pipe is claimed. However, for a full understanding of the tool, attention is directed to the following embodiment, shown in the drawings and described herein. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of the tool of the instant invention; FIG. 2 is an end view of the tool of FIG. 1; and, FIG. 3 is a section along the line III--III of FIG. 1. DESCRIPTION OF THE PREFERRED EMBODIMENT The tool 10, as seen in FIG. 1, resembles in general outline a miniature of the clam-shell buckets used on heavy construction cranes. The pairs of jaws 12 and 12a and 14 and 14a move similarly to those aforementioned buckets. However, a handle assembly 16 is fixed to jaws 12 and 12a, and a screw-lever assembly 18 is connected between jaws 14 and 14a and ratchets 20 and 20a for a greater mechanical force application between the jaws 12 and 14. By inspection of FIG. 2, it can be seen that the jaws 12 and 12a and 14 and 14a are each paired, as is ratchet plate 20 and 20a. Each pair operates as a unit, having cross-braces between them and a common axle 22 about which all of them rotate. For this reason, when the expression "jaw or "ratchet" is used in the singular, the plural is usually intended. The same is also true of the two-bar linkages 24 and 24a and 26 and 26a which connect jaws 14 to ratchet plates 20. Referring now to the Figures, front jaws 12 and 12a are mounted to pivot about axle 22, and are joined adjacent the gripping surfaces 28 by a stiffener-cross member 30. These gripping surfaces 28 are adapted to engage one flange of a repair clamp, with the two front jaws 12 and 12a spaced to straddle one bolt seat. At the top of the jaws 12 and 12a as seen in the Figures, another stiffener-cross member 32, which also acts as a retainer for a spring 34 and has a protruding portion 36, projecting outwardly for a purpose to be discussed later, connects the two front jaws 12 and 12a and reinforces them with upstanding flange portions 38 and 38a fixed to jaws 12 and 12a, respectively. Projecting rearwardly from front jaws 12 and 12a is the handle assembly 16. This assembly has a grip portion 40 at the extreme rear of the tool 10, which divides into a bifurcated member, each leg 42 and 42a being fixed to the outside of a front jaw, 12 and 12a respectively. The legs are fixed to their respective jaws by welding or other suitable means, and is located surrounding axle 22, with the legs having a suitable bore for receiving axle 22. Pivotally mounted atop the front jaws is a pawl 44, which is biased into engagement with the teeth 46 and 46a of ratchets 20 and 20a, respectively, by pawl spring 34. Pawl 44 has fixed on either side, stub shafts 45 and 45a which are received in bores through flanges 38 and 38a, respectively, and front jaws 12 and 12a, respectively. The shafts 45 and 45a are axially retained in these bores by suitable means, such as washers 47 and retaining rings 47a. As is usual with a ratchet-pawl combination, front jaws 12 and 12a can move clockwise about axle 22 as seen in FIG. 1, with pawl 44 riding over the teeth 46 and 46a, but in order to move the front jaws counter-clockwise with respect to the ratchets, pawl 44 must be lifted out of engagement. A handle portion 48 projects forwardly generally parallel to and spaced apart from, the protruding portion 36 of the upper cross member 32. By grasping handle 48 and protruding portion 36, pawl 44 may be lifted clear of teeth 46 and 46 a, and this is free to move either way about axle 22. Stop members are provided to limit the relative movement of jaws 12 and 12a with respect to ratchets 20 and 20a. On the outside of ratchet 20, between ratchet 20 and jaw 12, an L-shaped stop member 50 is fixed to ratchet 20, with the horizontal leg 52 projecting toward jaw 12. This stop is positioned to contact cross member 30 in the position shown in the Figures, to limit the travel of jaws 12 and 12a in the counter-clockwise direction as seen in FIG. 1. Additionally, another L-shaped stop member 54 is fixed on the outside of jaw 12, with leg 56 turned inwardly towards ratchet 20. When jaws 12 and 12a are rotated clockwise as seen in FIG. 1, leg 56 contacts leg 52 on stop member 50, preventing pawl 44 from running off ratchet teeth 46. The above-described front jaw-ratchet interaction, where the front jaws 12 and 12a are moved by handle 16 relative to ratchets 20 and 20a, is one lever assembly for fast closing action against relatively minor resistance. There is a second lever assembly for applying greater force, which will now be described. It was mentioned above that the ratchets 20 and 20a are connected to act as a unit. They have cross members similar to the lower cross member 30 of the front jaws 12 and 12a. One such cross member 58 is seen in FIG. 2, while the other cross member 60 is positioned on the axis of the connection journals of links 24 and 24a. These cross members 58 and 60 may be of any configuration that provides proper spacing of the ratchets 20 and 20a, and stiffens them so that they act together. It was found convenient to make cross member 58 of solid construction, while cross member 60 was made of hollow tubing (not shown), then a rod member 62 inserted through the tubing and projecting from the outer side of each of ratchets 20 and 20a, respectively, to provide a bearing for links 24 and 24a. This rod member 62 projects beyond the links on either side, and is fastened in place in any suitable manner. Peening the end of the rod is satisfactory, or retaining rings (not shown) received in suitable grooves in rod 62. The other end of link 24 (and of 24a) is journaled on a block 64 having its ends 65 and 65a shaped to receive the links 24 and 26 on one side, and 24a and 26a on the other. These link ends are fastened on the block using washer 66 and retaining ring 68 on each side. Rear jaws 14 and 14a are similarly constructed to the front jaws and the ratchets to act as a unit. A cross member 70 is fixed between the jaws near the gripping surfaces 72 (which are similar to gripping surfaces 28 on the front jaws). Another cross member 74 is positioned at the axis of the journal of the connection with links 26 and 26a. Cross member 74 is constructed similar to cross member 60, with hollow tubing providing rigidity and spacing to the jaws 14 and 14a, and a rod 76 is inserted through the tubing and projecting from the jaws 14 and 14a to provide a bearing for links 26 and 26a, respectively. The links are connected to the rear jaws in the same fashion as the front links are fastened to the ratchet plates as described above. Referring now to FIGS. 2 and 3, it will be seen that axle 22 is mounted in a longitudinal bore 78 in a block 80. A transverse bore 82 receives a threaded rod 84, which is fixed in place by a pin 86. A stop member 88 is fixed atop block 80 for a reason to be explained later. Axle 22 has block 80 centered on its longitudinal axis and ratchets 20 and 20a fit against the ends of block 80. Abutting ratchets 20 and 20a on axle 22 are rear jaws 14 and 14a, respectively. Abutting rear jaws 14 and 14a are spacer washers 90 and 90a, respectively. Bearing against the outer surfaces of spacers 90 and 90a are front jaws 12 and 12a and attached handle legs 42 and 42a, respectively. Retaining the whole assembly on axle 22 are washers 92 and 92a retaining rings 94 and 94a, respectively. Returning our attention to block 64 which has the links 24, and 26 and 24a and 26a mounted as pairs on respective ends, it can be seen by observing FIG. 3 that there is a transverse bore 96 through it aligned with bore 82 in block 80. Journaled in bore 96 is crank assembly 98. Crank assembly 98 has a stem 100 journaled in bore 96. Stem 100 has an enlarged portion 102 above block 64, which seats on a thrust bearing 104. Below block 64, another thrust washer, or bearing, 106 is retained in place by retaining ring 108 seated in a groove 110 in stem 100. A crank arm 112 and hand grip 114 provide the leverage to turn crank assembly 98. Stem 100 has a through bore 116, threaded on the bottom portion with threads 118 to match rod 84. The upper end of bore 116 is enlarged for provision of a stop member 120 fixed atop rod 84 by a capscrew 122. It will thus be seen that the second lever system comprises a two-bar linkage with provision for changing the angle between the links, thus moving the rear jaws 14 and 14a with respect to ratchets 20 and 20a by means of a screw jack type of leverage. The stop 120 limits the upward movement of crank assembly 98, while stop member 88, fixed to block 80, limits the downward movement of the crank. The foregoing describes a tool particularly useful in rapidly tightening leak repair clamps around a leak in a fluid pipe line. Referring to FIG. 1, in which the clamp is shown wrapped about the pipe at the point of leakage, the tool can be grasped by the hand grip 114 of the screw-lever assembly with one hand, and the grip portion 36 of the stiffner 32 with the other hand. The gripping surfaces 72 of rear jaws 14 and 14a are placed on one flange of the repair clamp, straddling a bolt with jaws 14 and 14a. The front jaws 12 and 12a are then lowered to contact the other flange of the repair clamp. Holding the screw lever assembly 18 in position with the hand holding grip 114, the other hand moves to grip 40 and is lifted (or brought toward the first hand). This moves front jaws 12 and 12a along with pawl 44, down over ratchet plates 20 and 20a and pawl 44 rides down teeth 46 and 46a of the ratchets. Upon encountering more resistance than the operator can overcome with this lever system, pawl 44 is allowed to seat itself in the nearest teeth of the ratchets, and the crank 98 is then turned to actuate the screw-lever assembly 18. By cranking crank assembly 98 downwardly on rod 84, the included angle between links 26, 26a and 24, 24a becomes greater, pushing ratchets 20 and 20a clockwise about axle 22 with respect to rear jaws 14 and 14a. Through engagement of teeth 46, 46a with pawl 44, front jaws 12, 12a are also rotated the same way, providing a much greater closing force between jaw surfaces 28 and 72 than was possible with the first lever system. Upon attaining shut-off of the leaking fluid, the bolts of the repair clamp can be tightened, and the tool of the subject invention removed. To remove the tool after the clamp bolts have been tightened, one merely releases the pressure by reversing the rotation of crank 98 for a portion of a revolution, then the pawl 44 may be disengaged from the ratchet teeth 46, 46a, and the front jaws 12, 12a moved to their fully retracted position with respect to ratchets 20, 20a (that shown in FIG. 1). After removing the tool from the clamp, it is a good idea to fully retract the crank assembly 98--that position shown in FIGS. 1 and 3--to be ready for the next use. It will be seen from the above description and the drawings that a novel tool and method of using it have been invented.

A tool for rapidly clamping a repair clamp tightly around a pipe. The tool has a two-stage operation, the first for rapidly taking up any slack, and the second for applying the necessary clamping force for tightening the clamp on the pipe.

BACKGROUND OF THE INVENTION 1. Technical Field of the Invention The present invention relates in general to thin film devices and more specifically to a method, apparatus and computer program product for identifying electrostatic discharge (ESD) damage to a thin film device. 2. Description of the Related Art Magnetic head disk drive systems are widely employed in the computer industry as a cost effective form of data storage. In a magnetic disk drive system, a magnetic recording medium, in the form of a disk, rotates at a high speed while a magnetic read/write transducer, generally referred to as a magnetic head, elevates slightly above the surface of the rotating disk. The magnetic head is attached to or formed integrally with a “slider” that is suspended over the disk on a spring-loaded support arm known as an actuator arm. As the magnetic disk is rotated at its operating speed, moving air generated by the rotating disk in conjunction with the physical design of the slider operate to lift the magnetic head allowing it to glide or elevate slightly above and over the disk surface on a cushion of air, generally referred to as an air bearing. The height at which the magnetic head elevates over the disk surface is typically only a few microinches or less and is primarily a function of the disk's rotation, the aerodynamic properties of the slider assembly and the force exerted by the spring-loaded arm. The magnetic head typically includes a magnetoresistive (MR) transducer or sensor element electrically connected to detection circuitry. MR sensors are well known in the art and are particularly useful as read elements in magnetic transducers, especially at high data recording densities. The MR sensor generally has a resistance that modulates in response to changing magnetic fields corresponding to magnetically encoded information. The detection circuitry detects the resulting changes in resistance by passing a sense current through the MR sensor and measuring the voltage drop across the MR sensor. The detected voltage signal is then used to recover information from the magnetic disk. The MR read sensor provides a higher output signal than an inductive read head. This higher output signal results in a higher signal to noise ratio for the recording channel and consequently permits higher area density of recorded data on a magnetic disk surface. A major problem encountered during the manufacturing and assembly of magnetic heads is the buildup of electrostatic charges on the various elements of a magnetic head or other objects that come into contact with the magnetic head and the accompanying spurious discharges of static energy generated. For example, static charges may be generated by the presence of certain materials, such as plastics, during the manufacture and subsequent handling of the magnetic heads. These charges can induce or result in electrostatic discharge. The net effect of such a discharge often damages or degrades the MR sensor in reading data correctly. Currently, the ESD screening regimes employed in the manufacture of MR sensors are typically of two general types. One approach is to employ a sampling method wherein a number of randomly chosen MR sensors are selected and undergo a detail inspection. This approach, however, may not catch all the sensors that may have suffered ESD damage. Another method is to take a first measurement of the resistance of every sensor prior to final fabrication and a second subsequent resistance measurement of all the sensors after final fabrication. The two resistance measurements are then compared with each other to identify potential ESD damage. This method, however, requires two measurements that increase the time required to fabricate a sensor. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method, apparatus and computer program product for identifying electrostatic discharge (ESD) damage to a thin film device. To achieve the foregoing object, and in accordance with the invention as embodied and broadly described herein, a method, apparatus and computer program product for identifying electrostatic damage to a thin film device is disclosed. The method includes (1) determining a cold resistance of the thin film device, (2) determining a hot resistance of the thin film device, (3) calculating a heating delta resistance (HDR) from the hot and cold resistances and (4) comparing the HDR to a threshold value to ascertain if the thin film device has suffered ESD damage. The HDR of the thin film device is characterized by the following relationship: HDR=(hot resistance-cold resistance)/(cold resistance). The present invention recognizes that there is a noticeable difference between the resulting heating delta resistance (HDR) value of a thin film device, such as MR sensor, that has suffered ESD damage from the HDR value of an undamaged device. The present invention utilizes this identified difference between the HDR values of a damaged and unaffected device to provide a more efficient and time effective screening mechanism that may be advantageously employed in, but not limited to, the manufacturing and fabrication processes of thin film devices. In one embodiment of the present invention, the thin film device is a magnetoresistive (MR) sensor. In a related embodiment, the MR sensor is a ansitropic magnetoresistive (AMR) sensor. Alternatively, the MR sensor may be a giant magnetoresistive (GMR) sensor. In yet another embodiment of the present invention, determining the hot resistance value of the MR sensor includes applying an operational current of the MR sensor. In an embodiment to be described in greater detail herein, the operational current ranges from about 4 milliamps to about 10 milliamps. In another related embodiment, on the other hand, determining the cold resistance of the MR sensor includes applying a current of less than 1 milliamp. The foregoing description has outlined, rather broadly, preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject matter of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form. BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: FIG. 1 illustrates a block diagram of an embodiment of a testing environment constructed according to the principles disclosed by the present invention; FIG. 2A illustrates an exemplary graph of calculated HDR measurements for a plurality of AMR sensors that have been subjected to a simulated ESD versus ESD ΔR; FIG. 2B illustrates an exemplary graph of calculated HDR measurements for a plurality of GMR sensors that have been subjected to a simulated ESD versus ESD ΔR; and FIG. 3 illustrates a high-level process flow of an embodiment of an ESD screening process employing the principles disclosed by the present invention. DETAILED DESCRIPTION With reference now to the figures, and in particular, with reference to FIG. 1, there is depicted a block diagram 100 of an embodiment of a testing environment constructed according to the principles disclosed by the present invention. In the illustrated embodiment, a magnetoresistive (MR) sensor 110 , e.g., a thin film device, is shown coupled to a conventional current generator 130 and a data acquisition device 140 via first and second electrical conductors 120 , 125 , respectively. First and second electrical conductors are typically part of MR sensor 110 . Data acquisition device 140 is also shown coupled to current generator 130 and a controller 150 . In an advantageous embodiment, data acquisition device 140 is an analog to digital (A/D) circuit card that is resident in controller 150 . Data acquisition device 140 is used to control the current output of current generator 130 and to measure the voltage Vout across first and second electrical conductors 120 , 125 . It should be readily apparent to those skilled in the art that current generator 130 , data acquisition device 140 and controller 150 may also be embodied in an automatic testing equipment (ATE) such as a Hewlett-Packard HP4145B Semiconductor Parameter Analyzer. Controller 150 , in an advantageous embodiment, is an IBM™ PC computer manufactured by IBM Corporation of Armonk, N.Y. It should also be readily apparent to those skilled in the art, however, that alternative computer system architectures may be employed. Generally, controller 150 , embodied in a PC computer, comprises a bus for communicating information, a processor coupled to the bus for processing information, a random access memory coupled to the bus for storing information and instructions for the processor, a read-only memory coupled to the bus for storing static information and instructions for the processor, a display device coupled to the bus for displaying information for a computer user, an input device coupled to the bus for communicating information and command selections to the processor and a data storage device, such as a magnetic disk and associated disk drive, coupled to the bus for storing information and instructions. The processor may be any of a wide variety of general purpose processors or microprocessors, such as the i486™ or Pentium™ brand microprocessor manufactured by Intel Corporation of Santa Clara, Calif. However, it should be apparent to those skilled in the art that other varieties of processors may be utilized in a computer system. The display device may be a liquid crystal device, cathode ray tube (CRT), or other suitable display device. The data storage device may be a conventional hard disk drive, floppy disk drive, or other magnetic or optical data storage device for reading and writing information stored on a hard disk drive, floppy disk drive, or other magnetic or optical data storage medium. In general, the processor retrieves processing instructions and data from a data storage medium using the data storage device and downloads this information into random access memory for execution. Thereafter, the processor then executes an instruction stream from random access memory or read only memory. Command selections and information input at the input device are used to direct the flow of instructions executed by the processor. The results of this processing execution are then displayed on the display device. MR sensor 110 generally comprises a sensing element (not shown) composed of a ferromagnetic material that is enclosed by a shield made of a highly permeable magnetic material such as Permalloy or Sendust. The shield minimizes the magnetic interferences from affecting the sensing element and thereby producing extraneous electrical pulses. Conductive leads, i.e., first and second electrical conductors 120 , 125 , attach electrically at the end portions of the sensing element to provide a means for measuring the resistance of the sensing element. As discussed previously, static electrical charges build up on the various components of the sensor assembly or on any object, equipment or person that may come into contact with the sensor. These charges are generated during the fabrication process and poses serious potential damage to the sensor. The electrical charges migrate from the areas at which they are generated to build up along conductive paths. The buildup of static charges subsequently discharge from one conductive element across a dielectric, which experiences “breakdown,” to another conductive element, in the manner of a capacitive discharge. The discharge typically causes damage by burnout or the like at the areas of the conductive material that function as terminals for the discharge of the stored static electrical energy. The present invention recognizes that there is a noticeable difference between the resulting heating delta resistance (HDR) value of a thin film device, such as MR sensor 110 , that has suffered ESD damage from the HDR value of an undamaged device. The present invention utilizes this identified disparity between the HDR values of a damaged and unaffected device to provide a more efficient and time effective screening mechanism that may be advantageously employed in, but not limited to, the manufacturing and fabrication processes of thin film devices. The HDR is defined by the following relationship: HDR=(hot resistance-cold resistance)/(cold resistance), where the hot resistance is the resistance of the MR sensor 110 when an operational current is applied to it. The cold resistance is the resistance of MR sensor 110 when a minimum current (typically 1 mA or less) is applied, i.e., no or nearly no Joule heating is generated during the measurement process. The values of the operational and minimum currents are dependent on the type of MR sensor and materials used to construct the sensor. In the illustrated embodiment, MR sensor 110 is a ansitropic magnetoresistive (AMR) sensor. Alternatively, in another embodiment, MR sensor 110 is a giant magnetoresistive (GMR) sensor. With both AMR and GMR type sensors, the operational current is typically four to ten milliamps. Similarly, with both AMR and GMR sensors, the minimum current utilized for the cold resistance measurement is generally less than one milliamp. The differences in the resistance values of the hot and cold resistances is a result of Joule heating within the sensor which is dependent on the heat capacitance of the sensor and the heat conductance of the materials surrounding the sensor; the HDR is a characteristic property of the sensor. The relationship between the HDR of a sensor and ESD damage incurred by the sensor is described hereinafter in greater detail with reference to FIGS. 2A and 2B. Referring now to FIGS. 2A and 2B, there are illustrated exemplary graphs illustrating the HDRs of AMR and GMR sensors following the application of simulated ESD transients across the sensors. In particular, FIG. 2A depicts an exemplary graph 200 of calculated HDR measurements for a plurality of AMR sensors that have been subjected to a simulated ESD versus change in resistance ESD ΔR (where ESD ΔR is defined as R post ESD initiation—R pre ESD initiation). FIG. 2B depicts an exemplary graph 210 of calculated HDR measurements for a plurality of GMR sensors that have been subjected to a simulated ESD versus ESD ΔR. An ESD event is initiated by applying a 150 nanosecond exponential decay current pulse, i.e., Human Body Model (HBM) transient, across the MR sensor to simulate an ESD transient. As illustrated in FIG. 2A, for the AMR sensors that have been damaged by the HBM transient, their calculated HDR values have decreased along with experiencing an increase in their overall resistance value. An AMR sensor that has encountered ESD damage typically suffers an increase in its resistance. For severely damaged AMR sensors, their HDR value is reduced to zero. For the GMR sensors that have suffered damage due to ESD, as depicted in FIG. 2B, HDR decreases for those sensors that have a resistance increase of less than forty ohms. The HDR of a ESD damaged GMR sensor could be significantly higher than its initial HDR value or have a negative value if its resistance increase as a result of ESD damage is greater than forty ohms. Referring now to FIG. 3, with continuing reference to FIG. 1, there is depicted a high-level process flow 300 of an embodiment of an ESD screening process employing the principles disclosed by the present invention. Process 300 is initiated, as depicted in step 310 , when the screening process is queued for execution. Next, as illustrated in step 320 , the cold resistance of MR sensor 110 is determined. This is accomplished by generating a reference current Iref, using current generator 130 , to simulate a minimum current of MR sensor 110 . In the illustrated embodiment of FIG. 1, controller 150 is executing an application program that instructs current generator 130 , through data acquisition device 140 , to initiate a current flow at a predetermined level and for a predetermined time. The minimum current is typically less than one milliamp. The value of the minimum current applied and the application period is dependent on the type of MR sensor under test and materials used to fabricate the MR sensor. Concurrent with the application of the minimum current, the voltage Vout across first and second electrical conductors 120 , 125 is measured by data acquisition device 140 that, in turn, provides voltage Vout to controller 150 . Controller 150 calculates the cold resistance of MR sensor 110 , as is well known in the art, by dividing voltage Vout by reference current Iref. Following the determination of the cold resistance of MR sensor 110 , the hot resistance of the MR sensor 110 is determined as depicted in step 330 . The determination of the hot resistance value is analogous to the manner in which the cold resistance was determined. In the case of the hot resistance, current generator 130 supplies a reference current Iref at an operational level, generally four to ten milliamps for a period of less than one second. Again, controller 150 calculates the hot resistance value of MR sensor 110 by dividing the measured voltage Vout by reference current Iref. It should be noted that although obtaining the cold resistance value prior to obtaining the hot resistance value is the preferred sequence, as shown in the illustrated embodiment, the alternative sequence of first determining the hot resistance value prior to determining the cold resistance value may also be advantageously employed. After obtaining both the hot and cold resistance values of MR sensor 110 , as illustrated in step 340 , the heating delta resistance (HDR) of MR sensor 110 is calculated. Using the previously determined hot and cold resistances, controller 150 calculates the HDR using the following relationship: HDR=(hot resistance-cold resistance)/(cold resistance). With the calculated HDR, controller 150 next, as depicted in step 350 , compares a predetermined threshold value with the HDR of MR sensor 110 to ascertain if MR sensor 110 has suffered ESD damage. The predetermined threshold value is calculated using the same process described above using a “good” or undamaged MR sensor to establish a baseline value. In other advantageous embodiments, the threshold value may be a constant value or, alternatively, a function of certain measured parameters of a batch of sensors, wafer or neighbouring heads on a wafer. The parameters, e.g., may be the stripe height, resistance or signal amplitude of the MR sensor. It should also be noted that the threshold value varies depending on the type of MR sensor under evaluation and type of materials employed to fabricate the MR sensor. Furthermore, the level of deviation of the HDR value of a MR sensor under test from the baseline HDR value used to screen a “failed” MR sensor is also dependent on the level of screening desired. For example, a more rigorous quality control standard may be implemented wherein MR sensors with HDR deviations larger than 2% are rejected. Typically, a baseline between 5 to 15% is employed. It should be noted that the baseline values utilized is very much design dependent. It should noted that although the present invention has been described in the context of a computer system, those skilled in the art will readily appreciate that the present invention is also capable of being distributed as a computer program product in a variety of forms; the present invention does not contemplate limiting its practice to any particular type of signal-bearing media, i.e., computer readable medium, utilized to actually carry out the distribution. Examples of signal-bearing media includes recordable type media, such as floppy disks and hard disk drives, and transmission type media such as digital and analog communication links. In a preferred embodiment, the present invention is implemented in a computer system programmed to execute the method described herein. Accordingly, in an advantageous embodiment, sets of instructions for executing the method disclosed herein are resident in RAM of one or more of computer systems configured generally as described hereinabove. Until required by the computer system, the set of instructions may be stored as computer program product in another computer memory, e.g., a disk drive. In another advantageous embodiment, the computer program product may also be stored at another computer and transmitted to a user's computer system by an internal or external communication network, e.g., LAN or WAN, respectively. The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

A method, apparatus and computer program product for identifying electrostatic discharge (ESD) damage to a thin film device. The method includes (1) determining a cold resistance of the thin film device, (2) determining a hot resistance of the thin film device, (3) calculating a heating delta resistance (HDR) from the hot and cold resistances and (4) comparing the HDR to a threshold value to ascertain if the thin film device has suffered ESD damage. The HDR of the thin film device is characterized by the following relationship: HDR=(hot resistance-cold resistance)/(cold resistance).

RELATED APPLICATIONS [0001] This application is a division of U.S. application Ser. No. 09/300,992 filed Apr. 28, 1999. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to information cards generally, and more specifically to a card having a plurality of separable elements or features, such as an embroidered patch and a heat transfer, that may each be removed from such card and applied to a consumer article either independently of, or in conjunction with each other. [0004] 2. Preliminary Discussion [0005] Keepsakes, memorabilia, souvenirs and the like serve important and useful functions in our society. Not only do they convey information and memorabilia concerning a particular experience, but they allow an individual to take and share such experience with their friends and family. [0006] For example, an individual who visits a city attraction, such as a zoo or the like, for the first time might purchase a hat adorned with the individual's favorite animal and the name of the zoo. In this example, the markings on such hat, and more particularly the name of the zoo, transform the function of the hat from one of complete utility to an ongoing remembrance of the individual's visit. Such markings also serve an important marketing purpose with respect to the direct purchaser, but they also serve as a general marketing medium, i.e. it is anticipated that others seeing the source indicator might also desire to visit or frequent such source. [0007] In general, whether a business is a pure “tourist trap,” such as Disney World® or the Statue of Liberty, or whether a business is a tourist trap by virtue of its placement in a particular city or location, such as the Washington Monument and the Smithsonian Museum, or whether the business is a purely local concern trying to attract customers, such as the sandwich shop down the street, the more people that frequent a particular location, the greater the benefit to the target business and the local economy. Consequently, businesses spend huge sums trying to attract customers or patrons to frequent their establishments. [0008] Once customers or patrons are “through the doors” so to speak, they are immediately enticed to spend money. Everyone knows that tourists, in particular, don't like to go away empty handed. But even more importantly, tourists like to purchase items that have lasting value. For example, a photograph, magnet, button or an informational booklet describing or displaying a particular experience has lasting value, and can usually be enjoyed by future generations. An article of clothing displaying an aspect of a particular memorable experience tends to have a lesser amount of lasting value, since clothing tends to wear out with age and excessive use, but does in fact have great exhibition value, especially when it is important for the owner to convey that he or she has taken part in a particular experience. Patrons of rock concerts, professional sports games and plays that purchase licensed or sanctioned or authorized clothing items are perfect examples, and are also usually walking advertisements for such events, while university and college attendees and parents of the same frequently will wear items adorned with their college name or logo to show their school spirit or pride in being connected with such an institution. [0009] Memorabilia usually come in one of two forms. The most popular type of memorabilia is the utilitarian or functional type, such as a shirt, button, magnet or the like. These items provide the patron with instant, expressive gratification as discussed above. The other type of memorabilia is the non-utilitarian or non-functional type, such as a booklet of information about a particular experience. Souvenir-type items in the form of booklets or other sources of audio, visual or literary-type information tend to have lasting value to the purchaser, and are usually intended to serve as a more complete reference commemorating a particular experience. [0010] It is rare, however, that prospective patrons or customers are provided with the ability to purchase an item or souvenir that is both functional and non-functional as described above. The item of the present invention is a unique product designed to convey information about a particular topic, i.e. in the form of a non-functional card-type medium, along with the provision of a plurality of functional keepsakes related to such topic and integrated into such product. The functional articles provided along with the information card may be separated from the information card and applied to another object to create an additional keepsake incorporating such functional articles. More specifically, the assembly of the present invention is comprised of an informational card having a first article, preferably a patch, embroidered emblem or the like, removably attached thereto and capable of being applied to a separate object, and a second article, preferably an adhesively applied heat transfer, removably attached thereto and capable of being applied to the same separate object either independently of, or in conjunction with the first removable article. Both removable articles bear indicia that are preferably related in some fashion to the material conveyed on the informational card. Therefore, the owner of the informational card of the present invention obtains the lasting benefit and value of having an item of written information about a particular subject or experience, and the further ability to create independent functional item or items related to such subject or experience. [0011] 3. Description of Related Art [0012] It is known to provide functional items in packages or as assemblies, with such functional items being related to information provided in or on such packages or assemblies. For example, a pizzeria that delivers to a local area might distribute cards with their menu printed thereon, and such cards might also have a magnet adhesively attached thereto with the name and phone number of the pizzeria printed on the face of such magnet. In this example, the functional aspect of the information card is the menu, while the non-functional aspect is the magnet that would presumably be attached to a prospective customer's refrigerator for easy access to the information printed thereon. While the magnet is essentially non-functional with respect to the business except with respect to whatever advertising information it may embody, it is at least potentially functional for the customer, which is the reason the customer hopefully retains it in the modern throwaway society. Furthermore, the magnet serves as an immediate reference for dialing the pizzeria and possibly ordering items that don't require the perusal of the lengthier menu, while the menu serves as a more complete reference for perusing the totality of options. [0013] Other methods of conveying information and functional articles in a single package are known in the greeting card art. For example, U.S. Pat. No. 2,547,359 to R. Bacharach discloses a combination greeting card and framed picture, with the picture shown through a cutout in the front of the card. The picture is removable and capable of being displayed in one's home, and thus provides the recipient with an essentially functional keepsake, while the card serves as a medium to convey a written message, i.e. non-functional information. [0014] U.S. Pat. No. 4,070,778 issued to H. H. Mahler et al. discloses a combination greeting/post card with a wax-like adhesive applied to the back surface of the card for display-like attachment to a wall or the like. The front sheet of the card may be separated from the back and mailed as a postcard, leaving the back sheet adhered to the wall. The adhesive surface transforms the nonfunctional back part of the card into a functional display piece, while the greeting or message printed thereon is retained as a keepsake or mailed as a postcard. [0015] U.S. Pat. No. 4,109,851 issued to D. T. Goates discloses a thermocontractive plastic plate adhesively applied to a postcard for subsequent thermal transformation into a novelty item. The card with the plate attached is placed in an oven and heated until the adhesive between the plate and the card dissolves and the plate shrinks into a novelty item. The Goates reference illustrates the application of a single, distinct, removable article from an information card, which article is transformed into a stand-alone novelty item. [0016] U.S. Pat. No. 4,200,222 issued to E. P. Feuer discloses a removable decal with a removable backing sheet that is viewed through a window in the front sheet of a greeting card. The decal may be removed from the card and applied to another surface, thereby enabling the user to create a single, functional item from the removable decal. Similarly, U.S. Pat. No. 4,439,941 issued to E. Halperin discloses a greeting card with a removable and reusable insert in the form of a multicolored embroidered emblem that is adhesively or heat-applied to a separate article. [0017] U.S. Pat. No. 5,284,365 issued to J. H. Stuart discloses a greeting card with a removable message insert of various embodiments. The removable insert is disclosed as being adhesively or magnetically attachable to a surface, or capable of being hung like a holiday ornament. [0018] None of the prior art references of which the inventor is presently aware discloses an informational-type card assembly designed to convey information about a particular topic along with the provision of a plurality of functional keepsakes related to such topic and integrated into such product, with such plurality of functional articles capable of being applied to a separate object either independently of, or in conjunction with each other. [0019] More specifically, none of the prior art references disclose an informational card having both a removable heat transfer and a removable emblem, patch or the like, each of which can be applied to separate articles independently of each other, or to the same article in an overlapping fashion, such that the combination of the applied articles on a single surface creates a homogeneous image consistent with, or distinct from an image shown on the informational card. OBJECTS OF THE INVENTION [0020] It is an object of the present invention, therefore, to provide an informational card having a plurality of separable elements or features that may each be removed from such card and applied to a separate article either independently of, or in conjunction with each other. [0021] It is a further object of the present invention to provide an informational card having both utilitarian and non-functional aspects in a single assembly. [0022] It is a still further object of the present invention to provide an informational card having a removable heat transfer and a removable emblem, patch or the like, each of which can be applied to separate articles independently of each other, or to the same article in an overlapping fashion. [0023] It is a still further object of the present invention to provide an informational card having a removable heat transfer and a removable emblem, patch or the like, which when applied to the same article in an overlapping fashion create a homogeneous image. [0024] It is a still further object of the present invention to provide an informational card having a removable heat transfer and a removable emblem, patch or the like, which when applied to the same article in an overlapping fashion create a homogeneous image consistent with, or distinct from an image shown on the informational card. [0025] It is a still further object of the present invention to provide a folding informational card having a removable emblem positioned along an inside surface of the card that is viewable from the front surface of the card. [0026] It is a still further object of the present invention to provide a folding informational card having a removable patch or emblem positioned along an inside surface of the card that is viewable from the front surface of the card and a removable heat transfer removably positioned along the back surface of the card. [0027] It is a still further object of the present invention to provide an informational card having a removable heat transfer that is removably positioned along the back surface of the card. [0028] It is a still further object of the present invention to provide an informational card having a removable heat transfer that is removably positioned along the back of the card and consists of the same image as viewed from the front of the card. [0029] It is a still further object of the present invention to provide a folding informational card having a removable patch or emblem positioned along an inside surface of the card that is viewable from the front surface of the card and a removable heat transfer removably positioned along the back surface of the card that is also viewable from the front surface of the card. [0030] It is a still further object of the present invention to provide an informational card having a removable heat transfer removably positioned along the back surface of the card and which is applied to a separate and distinct article via the direct application of heat through the information card. [0031] It is a still further object of the present invention to provide an informational card having a removable emblem, patch or the like positioned along a front surface of the card, and a removable heat transfer positioned along the back surface of the card, that are both applied to a separate and distinct article together via the direct application of heat through the front surface of the card. [0032] Still other objects and advantages of the invention will become clear upon review of the following detailed description in conjunction with the appended drawings. SUMMARY OF THE INVENTION [0033] An informational card incorporating a plurality of separable, functional articles that are removable from such card and capable of being applied to a separate article or articles, either independently of, or in conjunction with each other. More specifically, the informational card of the invention comprises a removable patch, embroidered emblem or the like, that may be adhesively or heat applied to a separate article, with indicia that bears some relation to the information conveyed on the card. A second removable article, preferably in the form of a heat transfer or the like, is also adhesively applied to the back of the information card, and such heat transfer or the like may be transferred to a separate article via the direct application of heat through the surface of the informational card. Means are provided in the second removable article to accommodate the placement or positioning of the first removable article during the conjunctive application of both removable articles to an article separate and distinct from the informational card. [0034] The informational card of the present invention is designed to function as a keepsake, item of memorabilia, souvenir or the like, conveying information about a particular topic or item of interest. The informational card of the invention is also equipped with removable functional articles that enhance the value of the card by providing the owner with the ability to create additional keepsakes capable of being worn or otherwise displayed separate and apart from the informational card. BRIEF DESCRIPTION OF THE DRAWINGS [0035] [0035]FIG. 1 is a front view of the first surface or cover of the information card of the present invention. [0036] [0036]FIG. 2 is a front view of the second and third surfaces, or inside surfaces, of the information card of the present invention. [0037] [0037]FIG. 3 is a front view of the fourth or back surface of the information card of the present invention. [0038] [0038]FIG. 3A is a front view of the fourth or back surface showing an alternative embodiment of the second removable article. [0039] [0039]FIG. 4 is a front view of the inside of the card showing non-opaque third and fourth surfaces of the card of the present invention. [0040] [0040]FIG. 4A is an alternative embodiment of the view of FIG. 4 with the addition of placement lines. [0041] [0041]FIG. 5 is a front view of the inside surfaces of the card of the invention showing the second removable article on the second surface. [0042] [0042]FIG. 6 is a front view showing application of the removable articles to a garment using the front cover of the card as a means of transferring such articles. [0043] [0043]FIG. 7 is a front view of a garment with a first article applied thereto. [0044] [0044]FIG. 7A is a front view of a garment with the first and second articles applied thereto to form a composite image. [0045] [0045]FIGS. 8 through 10 are front views of an alternative, two-sided embodiment of the information card of the present invention. [0046] [0046]FIG. 11 is a front view of the inside surfaces of an information card showing the second removable article positioned on a separate transfer sheet and inserted loosely between the second and third inside surfaces. [0047] [0047]FIG. 12 is a front view of the inside surfaces of an information card showing the second removable article positioned on a separate transfer sheet that is removably attached between the second and third inside surfaces. DESCRIPTION OF THE PREFERRED EMBODIMENTS [0048] The following detailed description is of the best mode or modes of the invention presently contemplated. Such description is not intended to be understood in a limiting sense, but to be an example of the invention presented solely for illustration thereof, and by reference to which in connection with the following description and the accompanying drawings one skilled in the art may be advised of the advantages and construction of the invention. [0049] [0049]FIGS. 1 through 3 are front views of the surfaces of a folded information card of the present invention, with FIG. 1 illustrating the first surface 100 or front cover, FIG. 2 illustrating the second and third surfaces 200 and 300 respectively or the surfaces that are viewed once the card is opened, and FIG. 3 illustrating the fourth surface 400 or the back cover with the second surface 200 shown partially therebehind, with the first and second opposing surfaces 100 and 200 forming a first leaf of the card and the second and third opposing surfaces 300 and 400 forming a second leaf of the card. While the card of the present invention will be shown and described in some cases as a folded card, generally consisting of four separate surfaces, it will be understood that the elements or aspects of the present invention can preferably be applied to a card having at least two surfaces, and up to “x” number of surfaces as the case may be, as long as the card is able to accommodate the removable articles of the invention to be described herein. Furthermore, while the informational card of FIGS. 1 through 3 is shown with the fold or spine 250 , such fold or spine 250 occurring between the second and third surfaces 200 and 300 , aligned in a generally vertical orientation, it will be clearly understood that such fold or spine could also be aligned in a generally horizontal orientation as is commonly seen in the marketplace. In other words, the card of FIGS. 1 through 3 could also be rotated ninety degrees and be operative in the same manner as described herein. [0050] [0050]FIG. 1 is a front view of the first surface 100 of the card of the invention with the card in a closed position. One viewing the front surface 100 of the information card of the invention would immediately notice certain desirable aspects of the card. First, there will usually be some identifying indicia 105 noted thereon representative of a particular experience or summarizing such experience. Such indicia 105 may, for example, be the name of a particular location, its logo or design or the like. Or such identifying indicia may be the title of a particular theme, as specifically shown in FIG. 1 with the title “PANSIES.” It will be appreciated that such indicia may also be textual or pictorial in nature. The first surface 100 also generally comprises an orifice or cutout 150 of a particular dimension, such that a first article 500 , shown here in the form of a bumble bee, removably attached to the third surface 300 (see FIG. 2) of the card will be visible through such orifice 150 . Surrounding such orifice or cutout 150 on the first surface 100 and around the first removable article 500 is a further design 125 , shown here as a grouping of pansies, which design or image 125 matches the design or image on the second article 600 (see FIG. 3, and FIG. 4 to be discussed), such second article 600 being removably attachable to the fourth surface 400 . Consequently, when both articles 500 and 600 are removed from the information card in a manner to be described herein, and applied to a separate object or article with the image of the first article 500 being surround by the image of the second article 600 , the combined image on such separate object will be identical to the image viewed by looking at the first surface 100 of the card of the invention when the card is in the closed position. [0051] The first removable article 500 is either two dimensional, such as a sticker or a decal, or more preferably three dimensional, such as a patch of the embroidered variety or non-embroidered variety or some other type of three dimensional object. While stickers and decals are literally three dimensional, it will be understood for purposes of explanation that the distinction between a sticker and patch is an actual noticeable depth dimension that creates a unique impression for the viewer, and is also often associated with a unique feel to the touch. For purposes of illustration, the first article 500 , again shown for purposes of illustration as a bumble bee, will be described as an embroidered patch, or just a patch, which is clearly an article that can be considered as having a noticeable depth dimension or is, in general, “raised” from a particular surface. A patch is useful to illustrate some of the more desirable features of the invention because a patch, which has a depth dimension, creates a unique sensation when touched, and tends to look nicer when applied to articles of clothing or the like (as opposed to a mere sticker or decal). A three-dimensional patch, when applied to the third surface 300 of the card of the invention, will preferably show through the second surface 200 and be viewable along with the first surface 100 when the card is in the closed position. The patch 500 would be equipped with a combination heat seal and pressure sensitive back, allowing the patch to be heat applied to a textile article, such as to clothing for example, or pressed on via the pressure sensitive adhesive to virtually any other article or surface. While the patch 500 is preferably equipped with a combination heat seal and pressure sensitive back, it could also be equipped with either a pressure sensitive back only, or a heat seal only, or a combination surface preferably. [0052] As shown in FIGS. 1 and 2, the cutout 150 extends between the first and second surfaces 100 and 200 respectively, and the outline dimension of the cutout 150 is designed to accommodate the dimension of the first article 500 , such that, as noted above, the article 500 might preferably extend through the cutout 150 and form part of the front surface view when the card is in the closed position and viewed in this manner. Of course, the cutout 150 could be dimensioned so that the article 500 does not extend through such cutout, but is instead merely exposed through such cutout, in which case its image will enhance the overall view of the front surface 100 as opposed to both its image and its depth, if any. If the first article 500 was a patch, then such patch would be exposed through the cutout 150 when the card is in the closed position, creating the impression that the patch 500 forms part of the first surface 100 , even though it would temporarily reside on the third surface 300 as shown in the embodiment of the invention in FIGS. 1 through 3. [0053] The second article 600 (see FIG. 3) removably attachable to the fourth surface 400 is also either two dimensional, such as a sticker or a decal, or three dimensional, such as a patch of the embroidered variety or non-embroidered variety or some other type of three dimensional object. For purposes of illustration, the second article 600 will be preferably in the form of an image-bearing heat transfer of the t-shirt variety, i.e. for transfer to t-shirts or the like, which does not have as extensive a depth dimension as a patch, but does have more of a depth dimension than a sticker or a decal. The second article 600 in the form of a heat transfer or the like would be equipped both with an adhesive or temporary adhesive first surface mountable to the fourth surface 400 of the card, and preferably a combination heat seal and pressure sensitive surface on the other side, or second side, of the transfer, allowing the transfer to be temporarily pressed onto a textile article and positioned thereon prior to the more permanent heat application of the transfer to such article of clothing or the like. Such application of the second article 600 to an article of clothing or the like would preferably occur by the direct application of heat, by an iron or other heat press or the like, applied to the third surface 300 of the card, which heat would transfer through such third surface 300 to the fourth surface 400 , thereby dissolving the temporary adhesive securing first side of the second article 600 to the fourth surface 400 and perfecting the heat application of the second article 600 to an article of clothing or the like. [0054] It will be understood that the first side of the article 600 will be the finished side, which will be ultimately viewable on the clothing or the like, and the second side may be unfinished. However, the second side may also be finished or decorated to form a more complete back to the card of the invention. Furthermore, in a more modern type of transfer, the transfer attached to the rear of the card or the fourth surface 400 will have merely a color transferable second surface that will, upon the application of heat, be transferred directly to the article of clothing, leaving the transfer itself still attached to the back of the card. In such case, the separate transfer will be attached to the back of the card or surface 600 by permanent adhesive. In a still further type of arrangement, the back of the card will itself be the transfer, the image and color of which may be transferred directly to the clothing surface by the application of heat from an iron or the like. [0055] As shown in FIG. 3, the second article 600 preferably has a cutout 155 , similar to the cutout 150 present between the first and second surfaces 100 and 200 , and bears an image that is preferably, although not necessarily, identical to the design or image 125 present on the first surface 100 of the card. If desired, the second article 600 might not have a cutout 155 but might instead have a continuation of the design or image 125 so that the second article, when applied to a separate object alone, i.e. without the conjunctive application of the first article 500 , does not appear discontinuous or with a cutout in the central portion of the article 600 . Since the second article 600 is preferably in the nature of a heat transfer or the like, the image or design on such second article 600 is usually not viewable by viewing the fourth surface 400 , since the design side of the second article would be initially, temporarily adhesively attached to the fourth surface 400 as shown. Since the second article 600 may, however, as explained above, be merely a heat transferrable pigment image on the back of the card or fourth surface 400 , the second article may be viewable on the back of the card as a mirror image of what will be transferred ultimately to a clothing article or the like (see FIG. 3A). [0056] The operation of the preferred embodiment of the card of the present invention is as follows. A recipient of the card would view the first surface 100 and notice a composite image or design comprised of the design or image 125 surrounding a first removable article 500 , such first removable article 500 appearing or peeking through a cutout 150 in the first surface 500 . Other indicia 105 on the first surface 100 would summarize or introduce the subject matter of the card to the recipient. By viewing the first surface 100 or cover of the card, the recipient is able to touch or feel the surface texture of the first article 500 . Another highly desirable feature of the cover image is that the cover of the card illustrates the composite design of the two articles, namely articles 500 and 600 , as such composite design might appear on a separate article, such as a shirt for example. Since the design or image of the second article 600 is preferably identical to the design or image 125 on the first surface 100 , and since the second article 600 comprises a cutout 155 that is preferably identical to the cutout 150 in the first surface 100 and/or is preferably identical to the outline dimension of the first article 500 , the recipient is able to initially view the composite image or design of both articles 500 and 600 as if such articles were removed from the card of the invention and applied to a separate article, such as a shirt, by the recipient. In other words, the recipient is able to view the card and realize the nature of the design that can be extracted from the articles attached to the card and applied to a separate article such as a shirt or the like. The recipient or purchaser of a card is therefore able to select a particular design or image that he or she would wish to apply to a separate article, such as a shirt, by merely perusing the front covers of the available cards. [0057] After the purchaser or recipient opens the card of the invention, he or she will immediately notice the first article 500 temporarily and preferably attached to the third surface 300 of the card. The second and third surfaces 200 and 300 will preferably be enhanced with further indicia, i.e. text, graphics or a combination of the two, or information about the particular experience illustrated by such card or about the topic of the card, and may even include written or pictorial (or both) instructions on how a recipient or user may fully utilize the removable articles attached to such card. Since such first article 500 is preferably equipped with a combination heat seal and pressure sensitive back, the article 500 may be removed from the surface 300 and pressed onto a separate object (see FIG. 7), or it may be temporarily applied to a garment via the pressure sensitive back and then heat applied in a more permanent fashion to such garment for a lasting effect (again, see FIG. 7). The design or image of the first article 500 is preferably, although not necessarily, printed on the surface of the card underneath the removably attached first article 500 , such that the design or image of the first article 500 is retained as part of the card once the actual first article 500 is removed from the card. The cutout 150 may also preferably, but by no means necessarily, be provided with a non-opaque covering that may also extend slightly forward to protect the article 500 while the card is displayed on a rack in a vending establishment. This would be particularly useful if the card of the invention was not vended it is own wrapping or other package-type container. [0058] Instructions will also preferably be provided on one of the surfaces of the card or in an insert-type sheet vended or otherwise provided with the card concerning the application of the second article 600 to a garment or the like. The second article 600 , as described above, is preferably a heat transfer, which is generally heat applied to a garment though the forceful application of heat via an iron or other type of heat press. The card of the invention provides the owner of the card with the necessary means to transmit the application of heat through the article 600 and onto a garment or the like. The surfaces of the card are impervious to the direct application of heat from an iron or the like, such that the second article 600 may be heat applied to a garment through the application of heat to the surface of the card directly upon the surface on which the article 600 is temporarily adhesively applied. In other words, one must merely position the card such that the second article 600 , currently adhesively secured to the fourth surface 400 , is in the proper location against a garment, and then apply heat directly to the third surface 300 (see FIGS. 2 and 3), which heat will be transmitted though the third and fourth surfaces 300 and 400 and to the second article 600 , which heat releases the article 600 from its temporary adhesive bond with the fourth surface 600 and activates the heat seal that creates a more permanent-type affixation to a garment or the like. Alternatively, as explained above and shown in FIG. 3A, merely the pigment from the transfer, which in this case may be the fourth surface or sheet itself, may be released by the heat and applied to an adjacent surface. [0059] It should be noted that another desirable feature of the card of the present invention, and more particularly the nature of the removable articles attached to the card, is the manner in which such articles may be removed and applied to a separate object either independently of, or in conjunction with each other on such separate object. Since the cutout 155 in the second article 600 is specifically designed to accommodate the dimensions of the first article 500 , it will be understood that a highly desirable feature of the card of the invention will be the conjunctive heat application of both articles 500 and 600 to a separate object, with such first article 500 fitting nicely within the cutout 155 of the second article 600 , such that a composite image may be created on such separate object that matches the image viewed on the cover of the card (see FIG. 1). In other words, the first article 500 can be removed from the surface of the card of the invention and adhesively applied to a garment or the like, and then the second article 600 can be positioned over the first article 600 such that the first article 500 is positioned within the orifice or cutout 155 of the second article, after which both articles can be simultaneously heat applied to a garment or the like, resulting in a composite image on such garment that is consistent with the image shown on the cover of the card when the card is in the closed position. Normally, if the first article 500 is an embroidered patch, such article 500 must be separated or protected by a separate sheet or covering from the direct application of heat from an iron or the like. However, the use of the card surface 300 (in FIGS. 2 and 3) to simultaneously and directly apply heat to the first and second articles, now located adjacent the fourth surface 400 , protects both articles from the hot surface of the iron or the like, and makes an additional sheet separate from the card itself unnecessary. Consequently, the information card of the invention acts as a protective surface during the heat application of the articles 500 and 600 to a separate garment surface or the like. [0060] It should be noted that the card surfaces are constructed in such a manner that the removal of the articles 500 and 600 through manual means, heat means or otherwise, does not destroy the integrity of the card surfaces or the indicia noted thereon, thus allowing the informational card of the invention to be used as a keepsake, souvenir or collectible, both with and without the removably attached articles attached thereto. [0061] The positioning of the information card of the invention against an article of manufacture, such as a garment or the like, in preparation for heat application of the second article 600 is fairly straightforward. The second article 600 will preferably be centered on the fourth surface 400 of the information card, and therefore, the card itself will serve as a positioning and guiding means against a garment or the like. FIG. 4 is a front view of an alternative embodiment of the information card of the invention, shown with non-opaque mounting surfaces 300 and 400 for easier positioning of the second article 600 against a garment or the like. Non-opaque can either mean transparent, semi-transparent, translucent or the like. A purchaser of the card of FIG. 4 might find it useful or desirable, for example, to be able to see the placement of the second article 600 , through the third and fourth surfaces 300 and 400 , and against a garment or the like. Non-opaque surfaces 300 and 400 would also be desirable if, for example, the first article 500 was removed and positioned on a garment, and it became necessary to view or visualize the subsequent placement of the second article 600 about or around the first article (via the cutout 155 ) prior to heat application of both articles to a garment or the like. It might also be desirable to have non-opaque card surfaces if the garment or the like has additional indicia that should be avoided or circumvented during the application of the image-bearing articles to such garment, i.e. necessitating precision placement of such articles to such garment. It might also be desirable to have placement lines 315 , as shown in FIG. 4A, for the positioning of the card against a garment surface or the like, although placement lines along a non-opaque surface might not be too desirable at times, particularly because the second article 600 would be viewable through the heat application surface prior to heat application of the articles 500 and 600 to the garment. [0062] [0062]FIG. 5 is a front view of surfaces 200 and 300 of an alternative embodiment of the information card of the present invention, showing the first article 500 removably attachable to the third surface 500 and the second article 600 removably attachable to the second surface 600 (as opposed to the fourth surface 400 as discussed above). The first surface 100 of the card of FIG. 5 would be unchanged as compared with the embodiments discussed above. Having the second article 600 attached to the second surface 200 as opposed to the fourth surface 400 has one distinct advantage over the embodiments of the invention described in connection with FIGS. 1 through 3, particularly during the heat application of both articles to a garment or the like. Once the first article 500 is removed from the third surface 300 and applied to a garment or the like, the second surface 200 must merely be placed directly over the first article in preparation for heat application to the first surface 100 and through the second surface 200 , such that the first article 500 extends through the orifice or cutout 155 in the second article 600 and cutout 150 between the first and second surfaces 100 and 200 . Having the first article 500 prepositioned on the garment and extending through the first and second surfaces of the card almost assures that the first article will be heat applied to the garment in proper position with respect to the second article, i.e. with the first article positioned within the cutout 155 of the second article. [0063] One of the disadvantages of having the second article 600 temporarily affixed to the second surface 200 , as opposed to the fourth surface 400 , is the space taken by the second article 600 , which otherwise might have contained written or pictorial descriptions or the like about the subject matter of the card. In other words, if the second article 600 were affixed to the back cover, or fourth surface 400 of the card, there would be more room to include informational material on the inside of the card, or on the second and third surfaces 200 and 300 . If the second article 600 were positioned on the inside of the card, it would be possible, although probably not desirable, to have some additional information noted on the back or the fourth surface 400 of the card. However, if the creator of the information card does not require a lot of room, or does not require that there be information noted on the second and third surfaces 200 and 300 , but instead only on the third surface 300 , then it really doesn't matter that the second article 600 is taking up room on the second surface 200 , which might otherwise just be blank. [0064] Another possible disadvantage of having the second article 600 on the second surface 200 with the heat being applied against the first surface 100 and directly against the first article 500 already prepositioned on a garment and peeking through the cutouts 150 and 155 , is that the direct topical application of heat against the first article 500 might harm in some manner the outer surface of the first article 500 , particularly if such first article is an embroidered patch. Usually, an additional sheet of material is placed between a patch and a direct application of heat from an iron or like, in order to protect the patch from the hot metal or other surface as the case may be. With the embodiment of FIG. 5, it would preferably be necessary to place an additional sheet of material over the first surface 100 prior to the application of heat against such surface in order to protect the first article 500 , which would be exposed through the cutouts 150 and 155 . One way to overcome this problem, without the need to find or otherwise obtain and use an additional protective sheet, would be to provide a temporary flap of protective material 510 (see FIG. 6) removably attachable to the first surface 100 and covering the entire cutout 150 , which flap of material would protect the exposed surface of the first article 500 during the heat application, and which flap of material 510 may then be easily removed from the first surface 100 after the articles have been transferred to the garment 900 or the like. Another way to overcome this problem would be to provide a temporary covering 520 (see FIG. 7) removably attachable to the outer surface of the first article 500 , which would protect the first article 500 during the direct heat application to a garment or the like, and would be easily removable by peeling or the like once the first article 500 was heat transferred to the garment. A further method of providing heat protection to the first article 500 would be to use a non-opaque dust cover, as described above, that is sufficiently thick or heat absorbent to also act as a heat shield over the article 500 . Of course, if the first article 500 is merely going to be adhesively applied to a separate object, such as a dry flat surface, then it might not be necessary to retain the protective covering 510 or 520 (see FIGS. 6 and 7) for any meaningful period of time, and it can be discarded if the owner of the card does not intend to heat apply such first article 500 . [0065] [0065]FIG. 8 is a front view of an alternative, two-sided or two-surfaced embodiment of the information card of the present invention, having a first or front surface 700 , a second or back surface 800 , and indicia or informational material 725 provided on such front surface 700 . The second removably attachable article 600 is shown in phantom attached to the second surface 800 in the same manner as previously described above, with a cutout 155 within such second article 600 designed to accommodate the placement of the first removable article 500 during simultaneous heat application of the two articles to a garment or the like. In the two-sided embodiment of the invention of FIG. 8, the first article 500 would be removably attachable to the first surface 700 , similar to the manner in which the first article 500 is removably attachable to the third surface 300 of FIGS. 2 and 4. In fact, the two-sided embodiment of FIG. 8 is essentially the same as the four-sided embodiment of FIGS. 1 through 3, for example, but without the first and second surfaces 100 and 200 of FIGS. 1 through 3. However, the first article 500 of FIG. 8 is actually attachable directly to the front cover 700 , as opposed to being viewable through a cutout 150 as in FIG. 1. [0066] Since the first article 500 of FIG. 8 is attachable directly to the surface 700 , it may be removed directly from such surface 700 and either pressure applied to a separate object, such as a garment, or temporarily pressure applied to a garment in preparation for the heat application of just the first article 500 , or the combination of the first and second articles 500 and 600 through the direct application of heat through the front surface 700 . As with all of the embodiments discussed herein, the surfaces of the information card may be opaque or non-opaque depending on the desired effect and the desires of the purchasers of such card. If the front surface 700 was completely opaque, then the positioning of the card of FIG. 8 over a prepositioned, pressure applied first article 500 , for the heat application of both articles to a garment, would be somewhat difficult. However, if the front surface 700 was non-opaque, or if just the surface 750 directly underneath the first article 500 (see FIG. 9 illustrating the first surface without the first article attached thereto) were non-opaque, the subsequent placement of the card over the prepositioned first article 500 , in order to line up the cutout 155 of the second article 600 with the outline or dimension of the prepositioned first article 500 , would be much easier, since the first article 500 would be viewable through such non-opaque section 750 of the front surface 700 . With the embodiments of FIGS. 8 and 9, the direct application of heat to the first surface 700 , with the first and second articles 500 and 600 prepositioned adjacent a garment or the like, is transmitted through the first and second surfaces 700 and 800 for the heat application of the articles 500 and 600 to such garment, and the first surface 700 also protects against the heat problems that might occur with the direct application of heat to the first article 500 (see. FIGS. 6 and 7 and the discussion related thereto). [0067] [0067]FIG. 10 is a front view of yet another alternative embodiment of the present invention, and more particularly an alternative embodiment of the invention described in FIGS. 8 and 9, showing a two-sided card having a removably attachable protectible layer 520 on the outer surface of the first article 500 , allowing for the direct application of heat to the first article 500 , and a heat dissolvable undersurface 750 directly under the first article 500 and extending between the first and second surfaces 700 and 800 . The heat dissolvable undersurface 750 allows the application of both articles 500 and 600 to a garment or the like without having to first remove and separately preposition the first article 500 on the garment. One would merely position the card of the invention on a textile surface, such as a shirt or other garment, and apply heat directly to the first surface 700 and the protective covering 520 of the first article 500 , which heat would dissolve the undersurface 750 and allow for the subsequent heat application of the first article 500 directly to the garment. [0068] Consequently, one could take the card of the invention adorned with informational material and removable articles, and apply such card directly to a garment, and the application of heat to such card would result in a garment adorned with the articles that were originally attached to the card, and a card containing information about a particular subject or experience (no longer having removable articles attached thereto). In other words, if one purchased the informational card of the invention, one would actually be purchasing the ability to create a separate keepsake in the form of a garment or other physical object adorned with heat applied articles, with the informational card serving as the method or means for applying such articles to such a garment. Once the articles are removed from the informational card, if desired, the informational card itself serves as a meaningful keepsake or memento, since it would generally be adorned with interesting information about a particular place, thing or event, with the removable articles being related in some fashion to such information on the card. [0069] The second removable article 600 , generally in the form of a heat transfer or the like, is primarily designed for heat application in conjunction with the first removable article 500 , generally a patch or the like. The informational card of the present invention could, for example, be vended with the second article loosely removable from the card assembly either as an insert sheet 920 to the card assembly (see FIG. 11), or loosely attached via breakable means 950 or the like (see FIG. 12). In FIG. 12 for example, the second article could be attached to a sheet that is connected to the card assembly via breakable means 950 , i.e. a tear line, fold line, perforated line or the like. In any case, the second article 600 should be able to accommodate the positioning of the first article 500 within an orifice or cutout of the second article, and it will understood that while only two removable articles are discussed herein, the information card of the present invention can comprise more than two removable articles, which then, when applied to a garment, or other surface or the like, would create an image that is consistent with the image shown on the informational card. [0070] The present inventor contemplates many uses for the informational card of the present invention. For example, auto dealerships wishing to advertise or solicit business might distribute information cards having information about the dealership printed thereon, accompanied by removable articles related to the dealership logo or the automobiles vended by such dealership. Zoos might distribute or sell informational cards for conveying information about the zoo or a particular animal at the zoo, with removable articles associated with such card and related to the zoo or a particular animal at the zoo. In fact, a zoo could vend many different informational cards having the same information printed thereon, but different removable articles associated therewith, directed to purchasers, for example, that might wish to create a garment each with a different type of animal. School, colleges and universities might sell informational cards with interesting information about the college, as well as removable articles associated therewith, which gives the purchaser the ability to create a personalized garment having school-bearing indicia applied thereto, while retaining the informational card for future reference about that particular school or institution of learning. Other typical uses would include, but would be by no means limited to, tourist attractions and theme parks, concerts and plays, or even manufacturers wishing to distribute information and articles about a new or emerging product. [0071] The informational card of the present invention, therefore, provides a useful tool for disseminating information about a particular person, place, thing or experience, while at the same time enabling recipients of the card to create additional keepsakes or mementos from removable articles attached to the card. The removable articles enhance the overall image of the card, and are designed to interact with each other during the final positioning and attachment to a garment or the like. The card of the invention also allows a recipient to review the final image or design created from the application of such removable articles to a garment or the like, and therefore, provides a means to discriminate between different informational cards. The card itself also provides a tool or the medium for application of the removable articles to a separate object, requiring only that the recipient have an iron or the like, with the card providing all of the other means for fully utilizing and applying the articles to a separate object such as a garment. [0072] While the present invention has been described at some length and with some particularity with respect to the several described embodiments, it is not intended that it should be limited to any such particulars or embodiments or any particular embodiment, but it is to be construed with references to the appended claims so as to provide the broadest possible interpretation of such claims in view of the prior art and, therefore, to effectively encompass the intended scope of the invention.

An informational card is disclosed incorporating a plurality of separable, functional articles that are removable from such card and capable of being applied to a separate article or articles, either independently of, or in conjunction with each other. The removable articles, such as a patch, embroidered emblem, heat transfer or the like, may be removed from the card and adhesively or heat applied to a separate article, with indicia that bears some relation to the information conveyed on the card. One of the removable articles has a cutout to accommodate the placement of a first removable article during the conjunctive application of a series of removable articles to an article separate and distinct from the informational card. The informational card of the present invention functions as a keepsake about a particular topic, and is equipped with removable articles that enhance the value of the card by providing the owner with the ability to create additional keepsakes capable of being worn or otherwise displayed separate and apart from the informational card.

This application claims priority under 35 USC § 119 (e) (1) of provisional application Ser. No. 60,064,309, filed Nov. 5, 1997. FIELD OF THE INVENTION The present invention is generally related to wireless communications systems, and more particularly to fixed wireless systems provided with HomeZone service whereby subscribers are provided communications service, and billed accordingly, depending on whether or not a subscriber's mobile station (MS) is located within one of its designated HomeZones. BACKGROUND OF THE INVENTION The implementation of wireless communications systems throughout the world is growing rapidly. This can be seen by the extensive sales and marketing of mobile cellular phone service throughout North America as well as the rest of the World. Existing and emerging technologies include AMPS, TDMA, CDMA, and GSM just to name a few. In these systems, a subscriber of an MS is typically billed for calls at a rate determined by a plan contracted to by the subscriber of the MS, whereby the rate per minute may be based on the time of day, the amount of use and the geographical location of the MS during a call. Another emerging wireless communication system is known as a fixed wireless system. In many parts of the world including Europe and Asia, subscribers are being provided with wireless communication transceivers e.g. mobile stations as their primary communication device for use within a residence, business and other defined locations. These fixed wireless transceivers are specially suitable where wireline services are to date not available, inadequate, or exceptionally expensive to install. With the decreasing cost of wireless transceivers and supporting infrastructure, those places of the world in need of new or upgraded communication systems are finding fixed wireless systems as economically attractive and versatile solutions. In fixed wireless communication systems, a subscriber's mobile station is assigned to one or more HomeZones. Each HomeZone defines a geographical home area in which the wireless mobile station is to receive and originate wireless calls at a predetermined low billing rate. While it is primarily intended that a subscriber will primarily use its mobile station within the HomeZone areas, these mobile stations may be transported by a subscriber outside the HomeZone calling areas and may be allowed to originate or receive calls outside the HomeZone area at another predetermined billing rate. The HomeZone service allows telecommunications providers to define the HomeZone calling areas for their MSs, where the tariff for calls originated and terminated in one of the HomeZones is different than the regular wireless tariff. The HomeZone service is attractive for telecommunications providers wanting to offer both fixed wireless and wireless services to subscribers over one mobile phone. One of the significant costs in providing wireline services is laying copper to each subscribers home. HomeZone service eliminates this cost by using wireless systems which don't require the cost of laying copper. The HomeZone service allows the provider to charge subscribers a particular tariff when they use their mobile station in one of their HomeZones at their wireline rate, and at another tariff when they use their mobile station outside their HomeZones at their wireless rate. The wireline rate is usually less expensive than the wireless rate. This attractive to consumers because they are charged the same low rates in their Homezone as they would have been charged by a wireline provider but without the hassle of multiple phones bills. As part of the HomeZone feature, on call termination, the location of the mobile station must be determined before the call is routed to the network access element, such as a visitors mobile switching center (VMSC), currently serving the mobile station, so that the network can potentially disallow or reroute the termination if the subscriber's mobile station is not in one of is HomeZones. There is a need to provide a method for determining whether a mobile station is located in one of its HomeZones, and also a method for speeding up the potential termination to the mobile station that may follow. SUMMARY OF THE INVENTION The present invention achieves technical advantages as a method of establishing call termination to a called mobile station in a wireless communication network which can be only allowed to receive call terminations in one of its HomeZones by determining the mobile station's location and identity before completing a call termination to the network access element currently serving the mobile station. In the preferred embodiment of the present invention, the method comprises first determining if a call termination received by a wireless communication network is a HomeZone type call. This may be done, for instance, at a gateway MSC by identifying prefix digits attached to the call. Upon determining that the call termination is a HomeZone type call, the location of the called mobile station to the cell level is first identified in the wireless communication network before routing the call termination to a network access element currently serving the mobile station. It is then determined if the identified location (e.g. serving cell of the mobile station) is within one of the mobile station's HomeZones. If the mobile station's location is determined to be within one of the mobile station's HomeZones, then the call termination is routed to the network access element currently serving the mobile station, and the call termination is completed to the mobile station by the network access element currently serving the mobile station. Preferably, the network access element comprises an MSC, but could comprise other equivalent network devices. If the mobile station is determined to be outside its HomeZones, the call may be routed by the network to the mobile stations voicemail, or to an associated wireless phone number and billed accordingly. According to the present invention, a mobile station radio link is established between the MSC currently serving the mobile station and the mobile station during the mobile station location process, wherein the call termination is completed to the mobile station on the same mobile station radio link. The radio link is preferably established by sending a PSI message from a HLR to the MSC currently serving the mobile station and paging the mobile station, whereby the mobile station then responds to the page with a page response to the serving MSC. If the mobile station is currently on a call, the location of the MS is known to the serving MSC and is returned to the HLR. If a subsequent termination arrives at the serving MSC, then the call termination to the mobile station is completed if the MS is configured to receive multiple calls e.g. call waiting, without establishing a new radio link between the MSC serving the mobile station and the mobile station. A PAGE_RESPONSE message which includes the mobile station's identity is generated in response to the page message by the mobile station. The identity included in the PAGE_RESPONSE message comprises preferably either the mobile station's International Mobile Subscriber Identity (IMSI) or Temporary Mobile Subscriber Identity (TMSI). If the response contains the TMSI, the TMSI is used by the serving MSC to find the IMSI. The page response also includes the mobile station's current Cell ID and the mobile station's current location area code (LAC). The mobile station's identity, LAC, and Cell ID are all sent by the MSC serving the mobile station to the home location register (HLR) of the mobile station. The mobile station's identity, LAC and Cell ID are then sent to a service control point (SCP) of the wireless communication network. The SCP determines if the mobile station is in one of the mobile station's HomeZones. If the SCP determines the mobile station is in one of its HomeZones, the SCP notifies the gateway MSC of the wireless communication network to complete the call termination to the mobile station. If the mobile station is determined to be outside its HomeZones, the call may be routed by the SCP to the mobile station's voicemail, or to an associated wireless phone number and billed accordingly. The present invention achieves technical advantages by determining the location of the mobile station to the cell level before the call is routed to the serving MSC, and speeding up the potential call termination to the mobile station that may follow. BRIEF DESCRIPTION OF THE DRAWINGS Referring now to FIG. 1, there is illustrated a typical fixed wireless communication network generally which is well suited to benefit from the method of the present invention; and FIG. 2 is flow diagram of a method of identifying a mobile station location to provide HomeZone service according to the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is generally shown at 10 a typical fixed wireless communication network which is adapted to provide HomeZone service according to the method of the present invention. The network 10 is seen to comprise a fixed network 12 which may comprise a public switched telephone network (PSTN), a gateway mobile switching center (GMSC) 14 and a subscriber switching center 16 which may be a MSC, serving a wireless mobile station (MS) 18 via a base switching station (BSS) 20 . MS 18 is seen to be assigned to one or more HomeZone location areas, one HomeZone area generally shown at 22 , which may be one geographic cell area served by BSS 20 . Associated with the serving/visited switching center MSC 16 is a visitors location register (VLR) 26 . A home location register (HLR) 30 is assigned to handle all of the MS 18 information, including the address of the MSC currently serving the MS, service capabilities, etc. A service control point (SCP) 32 interfaces with the GMSC 14 and HLR 30 . The present invention provides a method to determine if the MS 18 subscribing to a HomeZone service is in one of its HomeZones 22 before routing a call termination to the network access element 16 serving the MS, such as MSC 16 . One HomeZone 22 may be a subscriber's office, another HomeZone 22 may be a subscriber's home and so forth. The present invention allows the network 10 to potentially disallow the termination of a call to the MS 18 if the MS is not in one of its HomeZones 22 . The present invention also provides a method to precisely determine the MS's location. In addition, the present invention speeds up the potential termination to the MS that may follow by using the same radio link in the call termination that was used to find the mobile stations location. By way of illustration, but without limitation to the specific implementation that will soon be described, reference is made to the network of FIG. 1 and the message flow of FIG. 2 which illustrates the preferred embodiment of the present invention to provide the HomeZone feature. The present invention is illustrated and described in considerable detail to provide an understanding of implementation and use of the present invention. It is to be understood that some of the basic elements of the network 10 can be substituted with other equivalent network elements to provide the intended function. For instance, the gateway MSC (GMSC) 14 can be substituted with other network access elements e.g. routers, depending on the technology implementing the HomeZone feature. The present invention is ideal for implementation in a GSM network, but can function in other types of networks as well. With reference to FIG. 1, upon a call termination from the fixed network 12 to GMSC 14 , the GMSC 14 determines if the called number is a HomeZone type number. This is preferably done by ascertaining call data e.g. prefix digits provided with a call termination from the fixed network 12 , although other methods are possible. The GMSC 14 then queries the SCP 32 to determine if the termination is allowed to the intended MS 18 . To determine this, the SCP 32 then queries the HLR 30 to find the location of the MS 18 , and specifically, to determine if the MS 18 is located in one of its assigned HomeZones 22 . The HLR 30 then queries the MSC 16 known by the HLR 30 to be currently servicing the MS 18 , whereby the serving MSC 16 will page the MS 18 . The MS 18 responds to the page with a PAGE_RESPONSE message including its exact location including its current location area code (LAC) and current Cell ID, which is known by the mobile station based on broadcast messages by the serving cell. It is noted that the serving MSC 16 will know the LAC that the MS is located in, before paging, but the LAC is not enough information for the SCP to determine if the MS is in one of its HomeZones 22 . The PAGE_RESPONSE message also includes the mobile station identify, comprising the mobile station International Mobile Subscriber identify (IMSI) or Temporary Mobile Subscriber Identify (TMSI). If the response includes the TMSI, the TMSI is used by the serving MSC to determine the IMSI. The MS 18 will provide a page response containing its LAC and Cell ID to the serving MSC 16 , which information is then sent to the HLR 30 by the serving MSC 16 for that MS 18 . The HLR 30 then sends the LAC and Cell ID to the SCP 32 , which then instructs the GMSC 14 if and how to route the call to the MS 18 . For example, if the SCP 32 determines the MS 18 is in one of its HomeZones 22 , the call will be terminated to the MS 18 . If, however, the MS 18 is determined to be outside its HomeZones 22 , the call may be forwarded to the voicemail associated with MS 18 , or, terminated to an associated wireless phone number, e.g. MSISDN number, associated with the MS 18 wherein the subscriber is billed at the wireless rate, which is usually higher than the wireline rate. After sending the MS LAC and Cell ID location information back to the SCP 32 via the HLR 30 , it is specifically noted that the serving MSC 16 leaves the radio link (RR) connection up in anticipation of a reception of a call termination for that MS 18 . A timer at serving MSC 16 having a predetermined stop time e.g. 3 seconds is started at the serving MSC 16 once the MS LAC and Cell ID information has been sent to the HLR upon receiving the PAGE_RESPONSE message from the mobile station 18 . If a call termination does not arrive to the serving MSC 16 within the specified time, the established RR connection is then cleared by the serving MSC 16 . However, if the call termination does arrive within the predetermined time, the RR connection established between MSC 16 and MS 18 when the location of the MS was determined is then used. Thus, the MS 18 does not need to be paged again. The present invention achieves technical advantages by providing a significant improvement in time and processing over the prior art. The call set up time is improved by not having to page the MS again, by re-using the RR connection that was set up when the location of the MS was first determined. To more fully understand the preferred embodiment for providing the present invention, reference is now made to the preferred message flow diagram in FIG. 2 . The steps illustrated in FIG. 2 correspond to the message number illustrated in FIG. 1 . Again, this specific implementation is preferred, although variations are possible and covered by the present invention. At step 1 , the GMSC 14 is seen to receive an incoming call termination seen as an Initial Address Message (IAM) from the PSTN 12 . The GMSC 14 then determines if this call termination is to be a HomeZone termination. This is determined by ascertaining a call data e.g. prefix digits provided at the beginning of the call termination which identifies the type of call. At step 2 , the GMSC 14 initiates a query message to the SCP 32 by sending an InitDP message. At step 3 , the SCP 32 initiates identifying the location of the mobile station 18 by sending an AnyTimeIntegration message (ATI) to the HLR 30 . At step 4 the HLR 30 requests the called MS's location from the VLR 26 associated with the serving MSC 16 using the Provide MS Information (PSI) message. At step 5 , if the mobile station 18 is not on a call, the visited MSC 16 serving the mobile station 18 pages the mobile station 18 to ascertain its location. At step 6 , the mobile station 18 responds to this page with a PAGE_RESPONSE message to the serving MSC 16 containing its Location Area Code (LAC) and its Cell ID. In this regard, the present invention uses the PSI message in a novel way to trigger the serving MSC 16 to ascertain the MS 18 location. The MSC 16 starts the 3 second timer upon receipt of the PAGE_RESPONSE message, and leaves the established radio link to the MS 18 up in anticipation of an imminent call termination. At step 7 , the VLR 26 sends this LAC and Cell ID to the HLR 30 in a PSI response message. In step 8 , the HLR 30 forwards the LAC and Cell ID information to the SCP 32 using an ATI Response message. At step 9 , based on the specific location information received, the SCP 32 determines if the mobile station 18 is in one of its Home Zone's 22 , or if it is outside the HomeZones 22 . At step 10 , if the SCP 32 determines in step 9 that the mobile station 18 is in one of its HomeZones 22 , the GMSC 14 sends a Send Routing Info (SRI) message to the HLR 30 . If the SCP 32 , however, determines the MS 18 is out of its HomeZones, the call is either terminated to the voicemail of the MS 18 at the wireline rate, or terminated to the MS 18 but at the wireless rate. The servicing MSC 16 handles billing of the call. At step 11 , the HLR 30 responds to the GMSC 14 with a subscriber MS Roaming Number (MSRN) for the terminating mobile station 18 in the SRI ACK message. The MSRN number is generated by the serving MSC 16 and is included in the PRN ACK message per the GSM standard. At step 12 , the GMSC 14 then sends an IAM message to the visited MSC 16 . At step 13 , the visited MSC 16 terminates the call as normal, except that the Paging is skipped since it has already been done earlier in step 5 , as long as the timer at MSC 16 has not expired. The existing radio link established with MS 18 in step 5 is used. As a result, the Authentication Request message is the first message sent, if authentication is required, to the mobile station 18 after the IAM message is received from the GMSC 14 . The forgoing message flow as described with reference to FIG. 2 in view of FIG. 1 is the preferred implementation of the present invention, however, limitation to these specific messages is not to be inferred by the present invention. The present invention encompasses identifying if a MS is in one of its HomeZones prior to routing a call termination to the serving switching center for the mobile station, and using an existing RR connection to eliminate paging a mobile station a second time if a call termination is to be established. A timer is utilized at the switching center serving the MS, upon which the expiration of the timer of the RR connection is released. Though the invention has been described with respect to a specific preferred embodiment, many variations and modifications will become apparent to those skilled in the art upon reading the present application. It is therefore the intention that the appended claims be interpreted as broadly as possible in view of the prior art to include all such variations and modifications.

A method of establishing call termination to a mobile station of a called subscriber in a fixed wireless communication network which can be only allowed to receive call terminations in one of its HomeZones. The identification and location of the MS is ascertained prior to routing a call to the switching center serving the MS. The radio link between the serving switching center and the MS is maintained and used to terminate a call if the MS is determined to be within a HomeZone. The present invention eliminates the need to page a MS twice thereby speeding up the call termination. The MS provides its location area code and Cell ID to the serving/visited mobile switching center to facilitate the SCP identifying the MS's location prior to routing the call termination to the MS. The HomeZone call may be routed to a mobile station voicemail if it is determined to be outside its HomeZones, or, terminated to the mobile station but at a higher wireless billing rate.

FIELD OF THE INVENTION The present invention refers to a gob distributor for machines for the shaping of articles of glass or other materials which effectively and efficiently regulates the various movements of the distributor scoops towards respective shaping stations, which is of reduced size and easy to construct as compared with the known distributors, which can operate at higher speed of production by increasing the distance of fall of the gob between the feeder bowl and the scoops. BACKGROUND OF THE INVENTION In the manufacture of articles of glass or other materials molten glass is supplied in a continuous stream from a feeder bowl and is continuously cut by suitable cutters into portions known as gobs, which are distributed, by a gob distributor, to one or more cavities of a plurality of article-shaping stations, generally eight, which constitute the machine. Gob distributors for distributing the gobs to the shaping sections of the machine for the manufacture of articles of glass are well known and have achieved very effective development during the last few years, so that this type of mechanism has become an extremely efficient unit which makes possible the formation of articles of glass in multiple-station machines, which has increased the production capacity to a great extent. For example, U.S. Pat. No. 3,597,187 of Aug. 3, 1971, to Urban P. Trudeau assigned to Owens Illinois Inc. describes a molten glass gob distributor which comprises a pair of curved movable scoops supported on vertical shafts which by means of suitable gears are caused to turn through a predetermined angle of turn by a transverse bar which contains a cam follower which is pressed against the control cam, which has a shape such that it causes the curved scoops to turn simultaneously between one molding station and the next. The control cam in its turn is turned by means of a ring gear and a worm which is coupled to the shaft which is turned by a synchronous motor which turns the cam at a constant speed in synchronism with the operation controls, for instance the time drum which controls the various operations of each station of a multi-station machine for the shaping of glass articles. In U.S. Pat. No. 3,721,544 of Mar. 20, 1973, to Wasyl Bystrianyk and Francis A. Sarkozy, assigned to Emhart Corporation, there is also described a distributor for gobs of molten glass which comprises essentially a pair of rotatable curved scoops, a mechanism for supporting the curved scoops in dependent relationship side by side in order to turn them on each of their vertical axes, which mechanism includes a ring spur gear adjacent to the upper end of each scoop, a horizontally extending slideable member supported in a housing which supports the mechanism and which at one end has a portion which defines a rack for coupling with the spur gears on the scoops in order to turn them and at its other end a cam follower which is compelled by a spring to follow the path of a rotating multilobe cam, each of the lobes having a predetermined lift which results in a reciprocating movement which defines the position at which the curved scoops turn. This type of distributor has a cooling system for each scoop, consisting of a cooling passage of spiral configuration provided in a funnel-shaped portion. The cooling liquid generally employed is water and it is introduced through an entrance gate and into an annular passage through a neck in which the ring gear is defined within the profiled spiral groove in the inner portion of the tubular funnel and from there upward and downward within an aligned passage defining the scoop portion, having a similar return portion with reference to the other scoop and funnel. Finally, U.S. Pat. No. 3,775,083 of Nov. 27, 1973, to Nebelung et al., assigned to Emhart Corporation, describes and claims a gob distributor for machines for the forming of articles of glass which differs with regard to the manner of controlling the movement of the ring gears which in their turn move the shafts connected to the movable scoops since, in the particular case of the patent to Nebelung et al., such shafts are movable by means of ring gears which are connected to different racks, each of which is actuated by a fluid-driven linear motor, each one of which has a plurality of pistons which are driven through suitable distances and held by means of suitable stops in such a manner that a sequential movement can be imparted to each of the fluid-operated motors in order to enable the mechanism to move the scoops of the distributor between one station and the following one marked in the sequence by mere fluid pulses or signals instead of the use of the traditional cams which are employed both by Trudeau and by Bistrianyk. Nebelung, et al., however, use a plurality of individual pistons placed in tandem within respective pneumatic cylinders, which pistons are moved individually by air signals which come from each of the individual sections of the machine in order to move the distribution scoops in suitable sequence. In this distribution system, the cooling of each distributor scoop is constituted by the walls in the portions of the funnels, which have cooling passages arranged in a spiral through which the cooling water is directed. The cooling fluid protects the support of the frame of the gearing, conducted from the outside and directed via the upper portion of a groove through the profile of each spiral scoop and from there to a cooling passage within the scoops, the manufacture of this type of distributor being rather complicated. The problems which have been caused by the use of cooling passages for each scoop in the distribution of gobs of the different machines for the shaping of glass articles are known and reside essentially in the cooling of the bushings of the distributor scoops by means of a system of internal conduits of spiral configuration within the frame through which the cooling fluid is directed, its manufacture being more complicated and the size of the distributor being increased. Another substantial disadvantage present resides in the fact that the present distribution units, because they are of larger size, occupy a greater amount of space between the feeder bowl which contains the molten glass and the different scoops of the shaping stations, thus preventing operation at higher speeds by shortening the distance of fall of the gob. Another substantial disadvantage of the present distributors is that their manufacture is more complicated and their cost of manufacture greater. SUMMARY OF THE INVENTION A main object of the present invention is to provide a gob distributor for machines for the shaping of articles of glass or other materials which eliminates the liquid cooling system of the known distribution mechanism, replacing it with a cooling system which is less complicated. Another object of the present invenion is to provide a gob distributor which does not require water-cooled bronze bushings. Still another object of the present invention is, by reducing the space between the dosing source and the different channels of the shaping stations, to make it possible to work at higher speeds by increasing the height of fall of the gob. Still another object of the present invention is that the size of the distributor is reduced to half that of the present distributors, its construction being less complicated. A further object of the present invention is to provide a gob distributor which is of very great efficiency and precision and of lower competitive cost. The above objects and others related thereto are obtained preferably, in accordance with the present invention, by providing a gob distributor for machines for the shaping of articles of glass which comprises in combination: a support housing or frame; fastening means rigidly coupled to the upper end of each curved distributor scoop; a drive member and an auxiliary member which firmly and turnably hold the curved distributing scoops between them by fastening means in dependent linear relationship; linking means which turn on a central shaft fastened to the housing or support frame which holds the distributor scoops aligned closely together side by side and which, through their fastening means, link and transmit the movement of the drive member inversely to the auxiliary member which acts as support, so as to permit the simultaneous synchronized turning of all the scoops; and a positioner coupled to the drive member in order to impart movements of advance and retraction to it so as to move the curved scoops simultaneously through an angle to selective positions of delivery in a programmed sequence, with precise movements between the different sections of the shaping machine. BRIEF DESCRIPTION OF THE DRAWINGS The novel features which are considered characteristic of the present invention will be set forth in detail in the accompanying claims. However, the invention itself, both on basis of its organization and its method of operation, together with additional objects and advantages thereof, will be better understood from the following description, read in conjunction with the accompanying drawings, in which: FIG. 1 is a perspective view of the gob distributor of the present invention, showing a first arrangement for coupling with a positioner; FIG. 2 shows the inner rack-gear coupling along the section B--B' of FIG. 1; FIG. 3 shows the inner mechanism along a section A--A' through the distributor shown in FIG. 1; FIG. 4 is a top plan view of the distributor shown in FIG. 1; FIG. 5 is a convention perspective view of another embodiment of the present invention, showing a second arrangement for coupling with a positioner. DETAILED DESCRIPTION FIG. 1 shows the distributor 40 of the present invention which comprises essentially a support frame or housing 10 having four distributing scoops 15 arranged in tandem and each one having a gob receiver receiving gobs from a feeder bowl (not shown) in order to distribute them to the different forming sections (not shown) of the machine for the molding of glass articles. This set of scoops 15 is moved in synchronism by a drive rack 11 which is coupled to a positioner (not shown) in order to impart movement in a given synchronized sequence, in combination with an auxiliary rack 14. Referring now to FIG. 2, a view along the section line B--B' of FIG. 1, there is seen a distributing scoop 15 which has coupled to it a ring gear 30 integrated with the upper part of the distributor scoop 15; this ring gear 30 is held firmly between an upper plate or flange 50 and a lower one 27; each scoop 15 is coupled between a pair of toothed racks 11 and 14; the toothed rack 11 is a drive rack which transmits its movement by means of the positioner (not shown) via the gear 30 to the auxiliary toothed rack 14 in order to move the scoops 15 in synchronism to the respective shaping sections (not shown). The drive rack 11 is supported by the frame 10 by means of a guide 29 which is fastened to the structure of the frame 10 and which makes it possible for the drive rack 11 to slide longitudinally. The auxiliary rack 14 also has a guide 25, not fixed, which makes it possible to adjust the play present between the two racks 11 and 14 and gears 30 due to the wear which they suffer, due to the constant movement, in the course of time. The guide 25 is adjusted by means of a compensating screw 24 for each scoop 15 and is supported by the frame 10. The gears 30 are intercoupled to each scoop 15 by a lower plate or flange 27 which permits correct assembly between each gear 30 and scoop 15 and, as a result, upon the transmission of the movement via the drive rack 11, permits each scoop 15 to distribute in proper and orderly manner the gobs or batches of molten glass to the different forming sections of the machine. This connection between the ring gear 30 and the scoop 15 is effected via the fastening means 51 and 52. In the lower part of the gear 30, located at the height of the plate 27 which connects the scoop 15 and the gear 30, there is a pan-shaped part 26 which makes it possible to recover the oil by gravity in a tank 35 and to be able to recirculate this oil for the lubrication of the inner mechanism of the distributor 40 and furthermore prevent its leaking out, for which there is furthermore interposed an oil seal ring 28 between the lower plate or flange 27 and the gear portion 30. With respect to the upper part of the distributor 40 there is a cover 19 which bears, connected to it, a fixed funnel portion 21 for each distributor scoop 15, which avoids the diverting of the gob out of the distributor. FIG. 3 shows a view along the section A--A' of FIG. 1 at least one gear 31, which may be coupled directly or indirectly to the frame 10 and the function of which is to impart synchronism to the auxiliary rack 14, providing support and movement to the gears 30 which, coupled with the scoops 15, comply with the movement of the drive rack 11, moving at the same time from one position to the other. This gear 31 is supported on the cover 19 of the distributor 40 by an inner bushing 20 which is rotatable on a pin 39 which is supported by separate fastening means 32, 53 on a plate 17. Through this gear 31, the drive rack 11 and the auxiliary rack 14 maintain the gears 30 aligned side by side and the movement of the drive rack 11 is transmitted to the auxiliary rack 14 to permit the synchronized turning of all the gears of the scoops. The fastener 32 extends above the cover 19 of the distributor 40, said cover having a slot (not shown) which permits the sliding of the aforementioned gear 31 laterally of the cover when there is an adjustment between racks 11 and 14, by means of the guide 25 and screw 24, which are shown in FIG. 2. FIG. 4 shows a plan view of the distributor 40 in which there can be seen the coupling present between the drive rack 11, the gears with their projecting plates 17 and 50 and the auxiliary rack 14. Referring now to FIG. 1, coupling directly or indirectly to the frame 10 is an air cooling system 36 which makes it possible to cool the inner mechanism of the distributor 40 through the internal passages 23 shown in FIG. 2. This cooling by air will prevent the overheating of the gears 30 and both racks 11 and 14. Referring in particular to FIG. 5, there is shown therein another arrangement of the distributor 40 for coupling with a positioner of the fork type (not shown) which includes a connecting rod 60 articulately coupled at one of its ends to the drive rack 11. As is well known in the art, the stream of molten glass issuing from the feeder bowl which is continuously cut into portions known as gobs, which are then distributed to the different forming sections (not shown) by means of the scoops 15 which move in synchronism from one position to the next via the drive rack 11 and the auxiliary rack 14 and which in a given sequence feed the gobs to the different sections of the machine for the shaping of glass articles. It will be understood that the invention is not limited to the embodiment set forth above and that those skilled in the art will be able, based on the teaching of the present invention, to make changes in the design and distribution of the component parts of the invention which fall clearly within the true spirit and scope of the invention which is claimed in the following claims.

A gob distributor for glass-working machines in which the scoops are indexed angularly in unison by paired racks which provide the sole support and positioning members for the scoops.

TECHNICAL FIELD [0001] The present invention relates to an electric parking brake device and, in particular, an electric parking brake device configured such that a parking lever in a drum brake is driven from a return position to an operating position by forward drive of an electric actuator to drive a brake shoe from a return position to an operating position and the parking lever is driven from the operating position to the return position by reverse drive of the electric actuator to drive the brake shoe from the operating position to the return position. BACKGROUND ART [0002] The electric parking brake device of this type is described in, for example, the following Patent Literature 1. A parking brake switch is actuated and operated to make it possible to drive an electric actuator forward and to make it possible to drive a parking lever from a return position to an operating position (more specifically, to set a parking brake in an operating state (lock state)). When the parking brake switch is operated to be released to make it possible to reversely drive the electric actuator and to make it possible to drive the parking lever from the operating position to the return position (more specifically, to set the parking brake in a release state (release state)). CITATION LIST Patent Literature [0003] Patent Literature 1: Japanese Unexamined Patent Publication No. H11-105680 [0004] In the electric parking brake device described in the Patent Literature 1, an electric motor (motor) included in the electric actuator is rotated forward to make it possible to drive the electric actuator forward, and when a predetermined current or more flows in the forward-rotating electric motor, the electric motor is stopped to make it possible to always obtain a predetermined parking brake force. The Patent Literature 1 also describes that the electric motor (motor) included in the electric actuator is reversely rotated to make it possible to reversely drive the electric actuator, and, when a current flowing in the reversely rotating electric motor is a no-load current, a power supply to the electric motor is disconnected. SUMMARY OF INVENTION [0005] In the electric parking brake device described in the Patent Literature 1, depending on a current value flowing in the electric motor, an operation/stop state of the electric motor can be advantageously controlled (a sensor for electrically detecting the state of a parking lever is advantageously unnecessary). However, the brake shoe of the drum brake generally includes a return spring biasing the brake shoe toward the return position. For this reason, when the parking brake is released, the reverse drive of the electric actuator is assisted by the return spring. [0006] Thus, a timing at which a current flowing in the reverse-rotating electric motor becomes a no-load current may be disadvantageously different from a timing at which the parking lever returns to the return position. For this reason, when the parking brake is released, the parking lever may be incompletely returned or excessively returned disadvantageously. When the parking lever is incompletely returned, for example, the brake is disadvantageously dragged. When the parking lever is excessively returned, for example, a drawback such as a delay of response in the next operation of the parking brake may occur. [0007] The present invention has been made to solve the above problem (to prevent a parking lever from being incompletely returned or excessively returned in a release state of the parking brake), and has as its object to provide [0008] an electric parking brake device configured such that a parking lever in a drum brake is driven from a return position to an operating position by forward drive of an electric actuator to drive a brake shoe from a return position to an operating position and the parking lever is driven from the operating position to the return position by reverse drive of the electric actuator to drive the brake shoe from the operating position to the return position, wherein [0009] the electric actuator includes [0010] an electric motor which can be rotationally driven forward/reversely and the operation of which can be controlled by a motor control unit depending on a rotational load, [0011] a conversion mechanism which can convert rotational motion into linear motion, can move the parking lever from the return position to the operating position in a forward drive state in which the electric motor rotates forward, and can move the parking lever from the operating position to the return position in a reverse drive state in which the electric motor reversely rotates, and [0012] a load applying mechanism drives a constituent member of the conversion mechanism after the parking lever moves from the operating position to the return position by reverse rotation of the electric motor to apply a rotational load increasing depending on a drive amount of the constituent member to the electric motor, and [0013] the motor control unit includes a calculation unit which calculates a rotational load determination value to determine whether a rotational load applied to the electric motor by the load applying mechanism when the electric motor reversely rotationally drives is a set value or more on the basis of a current supplied to the electric motor, and a reversely rotational drive stop unit which stops the reversely rotational drive of the electric motor when the rotational load determination value is a reference value or more a set time after the reversely rotational drive of the electric motor is started. [0014] In the electric parking brake device according to the present invention, the motor control unit can obtain a parking brake operation such that the electric motor is rotated forward by an actuating operation of the parking brake switch, and the forward-rotating electric motor is stopped by a current value obtained when a rotational load acting on the forward-rotating electric motor becomes a set value. At this time, when the parking brake switch is actuated and operated, the electric motor rotates forward, and the parking lever at the return position is driven from the return position to the operating position by forward drive of the electric actuator to drive a brake shoe from the return position to the operating position. At this time, since the device is set such that the forward-rotating electric motor is stopped by a current value (target current value) obtained when the rotational load (load obtained when the brake shoe moves to the operating position and is brought into press contact with the brake drum) acting on the forward rotating electric motor becomes the set value, predetermined parking brake force can be always obtained. [0015] The motor control unit is set such that the electric motor is reversely rotated by a releasing operation of the parking brake switch, and the reversely rotating electric motor is stopped by a current value obtained when a rotational load acting on the reversely rotating electric motor becomes a set value, so as to make it possible to release the parking brake. At this time, when the parking brake switch is released, the electric motor reversely rotates, and the parking lever at the operating position is driven from the operating position to the return position by reverse drive of the electric actuator to drive the brake shoe from the operating position to the return position. At this time, since the device is set such that the reversely rotating electric motor is stopped by a current value obtained when the rotational load (load obtained by the load applying mechanism) acting on the reversely rotating electric motor becomes the set value, the parking lever can always be stopped in a state in which the parking lever is always returned to the predetermined return position. [0016] Thus, in the electric parking brake device according to the present invention, the parking lever can be prevented from being incompletely returned or excessively returned when the parking brake is released. In this manner, a drawback (for example, drag of the brake) caused by incomplete return of the parking lever can be prevented, and a drawback caused by excessive return of the parking lever (for example, delay of response in the next operation of the parking brake) can be prevented. [0017] In the electric parking brake device according to the present invention, the operation/stop of the electric motor can be advantageously controlled by a current value supplied to the electric motor (a sensor for electrically detecting the state of the parking lever is advantageously unnecessary), and the motor control unit can be simply configured at low costs. Since the motor control unit includes the calculation unit and the reversely rotational drive stop unit, the reversely rotational drive of the electric motor can be accurately stopped, and a rotational load required by the load applying mechanism can be set to be small. As a result, the load applying mechanism can be miniaturized and manufactured at low costs. [0018] In execution of the present invention described above, [0019] the rotational load determination value is a current value supplied to the electric motor, and a sum of a no-load current value detected in a reversely rotational drive state of the electric motor and a preset predetermined current value can also be defined as the reference value. [0020] In this case, a sum of the no-load current value and the preset predetermined current value is defined as the reference value, and the no-load current value serves as a part of the reference value. For this reason, a fluctuation in performance caused by a manufacturing error or the like in the conversion mechanism or the load applying mechanism can be excluded. Thus, determination accuracy when the reversely rotational drive of the electric motor is stopped can be improved, and a rotational load required by the load applying mechanism can be reduced. As a result, the load applying mechanism can be miniaturized and manufactured at low costs. [0021] In execution of the present invention described above, [0022] the rotational load determination value is a differential value of a current value supplied to the electric motor, and the preset predetermined value can also be defined as the reference value. [0023] In this case, since the rotational load determination value is the differential value of the current value supplied to the electric motor, in comparison with the case in which the sum of the no-load current value detected in the reversely rotational drive state of the electric motor and the preset predetermined current value is defined as the reference value, a stop timing can be more quickly determined. For this reason, determination accuracy when the reversely rotational drive of the electric motor can be improved, and the load applying mechanism can be further miniaturized and manufactured at low costs. [0024] In each of the cases of the present invention, [0025] the motor control unit can also include an abnormal-state reversely rotational drive stop unit which, when it is determined that the rotational load determination value is a reference value or more within the set time except for an operation initial time zone in which a current supplied to the electric motor is unstable from the start of the reversely rotational drive of the electric motor, stops the reversely rotational drive of the electric motor, and an abnormality notification unit which notifies of abnormality. In this case, the abnormal electric actuator in the device can be rapidly detected to stop the abnormal operation and to make it possible to notify of the abnormal operation. BRIEF DESCRIPTION OF DRAWINGS [0026] FIG. 1 is a perspective view showing an embodiment of an electric parking brake device according to the present invention. [0027] FIG. 2 is a front view of the electric parking brake device shown in FIG. 1 . [0028] FIG. 3 is a sectional view showing a configuration of an electric actuator in the electric parking brake device shown in FIG. 1 and FIG. 2 , and shows a cross-sectional plan view of a coupling part between a parking lever and a rod along 3 - 3 line in FIG. 4 . [0029] FIG. 4 is a front view showing the parking lever and the rod shown in FIG. 3 and a coupling mechanism coupling the parking lever and the rod. [0030] FIG. 5 is a flow chart showing a main routine executed by an electric control device shown in FIG. 3 . [0031] FIG. 6 is a flow chart showing a sub-routine executed in a lock control process shown in FIG. 5 . [0032] FIG. 7 is a flow chart showing a sub-routine executed in a release control process shown in FIG. 5 . [0033] FIG. 8 is a flow chart showing a sub-routine executed in an in-abnormal-state process shown in FIG. 7 . [0034] FIG. 9 is a flow chart showing a sub-routine executed in an in-normal-state process shown in FIG. 7 . [0035] FIG. 10 is a graph showing a relationship between a time (time in which the electric motor reversely rotates) in which the sub-routines shown in FIG. 7 , FIG. 8 , and FIG. 9 are executed and a motor current (current supplied to the electric motor). DESCRIPTION OF EMBODIMENTS [0036] Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 to FIG. 4 show an embodiment of an electric parking brake device according to the present invention. The electric parking brake device according to the embodiment includes a drum brake 10 having a parking brake mechanism and an electric actuator 20 driving the parking brake mechanism. [0037] The drum brake 10 , as shown in FIG. 1 and FIG. 2 , includes a disk-like back plate 11 , one pair of brake shoes 12 and 13 assembled on the back plate 11 , an anchor block 14 , a wheel cylinder 15 , and the like. The back plate 11 is configured to be fixed to an attaching part (not shown) on a vehicle body side. [0038] The brake shoes 12 and 13 are assembled on the back plate 11 such that the brake shoes 12 and 13 can move in a specific direction (direction along a plate plane) with reference to the back plate 11 , and integrally include arc-shaped linings 12 a and 13 a pressed against a brake drum (not shown) in a brake operating state, respectively. A coupling member 16 with adjustment mechanism and return springs S 1 and S 2 are assembled between the brake shoes 12 and 13 . [0039] The brake shoe 12 on the left in FIG. 1 and FIG. 2 is configured to be engaged with a left piston (not shown) of the wheel cylinder 15 at an upper end of the brake shoe 12 , engaged with the anchor block 14 at the lower end, and pressed and spread to the left toward the brake drum (not shown) in a brake operation state. A parking lever 17 is swingably assembled on the brake shoe 12 . [0040] On the other hand, the brake shoe 13 on the right in FIG. 1 and FIG. 2 is configured to be engaged with a right piston (not shown) of the wheel cylinder 15 at an upper end of the brake shoe 13 , engaged with the anchor block 14 at the lower end, and pressed and spread to the right toward the brake drum (not shown) in a brake operation state. A return spring S 3 (the spring S 3 has an upper end locked on the back plate 11 and a lower end locked on the brake shoe 13 ) is assembled on the brake shoe 13 . [0041] The anchor block 14 is fixed to a lower part of the back plate 11 in the drawing by using one pair of fixtures 14 a and 14 b . The wheel cylinder 15 is fixed to an upper part of the back plate 11 in the drawing by using one pair of fixtures 15 a and 15 b . The wheel cylinder 15 includes one pair of pistons (not shown) which come away from the left and right sides in the operation of the brake to open the left and right brake shoes 12 and 13 , the wheel cylinder 15 housing the pair of pistons therein. [0042] A coupling member 16 is tiltably engaged with an upper part of the brake shoe 12 at a left-end part and tiltably engaged with an upper part of the parking lever 17 , and tiltably engaged with an upper part of the brake shoe 13 at a right-end part. The coupling member 16 is configured to have a length which can be automatically adjusted (increasable) by a known adjustment mechanism 16 a depending on amounts of abrasion of the linings 12 a and 13 a. [0043] The parking lever 17 is disposed along the left brake shoe 12 in the drawing and tiltably (rotatably) coupled to the brake shoe 12 at the upper-end part by using a pin 17 a and a clip 17 b . The parking lever 17 is configured such that the parking lever 17 , at the lower end, as shown in FIG. 3 , is engaged with a coupling mechanism 29 on the electric actuator 20 and driven in the left-right direction by the coupling mechanism 29 (rotatably driven around the pin 17 a ). [0044] The electric actuator 20 , as shown in FIG. 1 and FIG. 2 , is disposed in the drum brake 10 . The electric actuator 20 , as shown in FIG. 3 , includes an electric motor 21 , a conversion mechanism 22 , and a stopper 27 and a disk spring assembly 28 which function as a load applying mechanism, and also includes the coupling mechanism 29 . The electric motor 21 can be rotationally driven forward/reversely, and is configured to be operated with a motor control unit (electric control device) ECU depending on a current value changing depending on a rotational load. The current value depending on the rotational load can be detected by a current monitor IM included in the motor control unit (electric control device) ECU. [0045] The conversion mechanism 22 can convert rotational motion of the electric motor 21 into linear motion of a rod (screw shaft) 22 e (swinging operation of the parking lever 17 through the coupling mechanism 29 ), can axially move the rod 22 e from a return position (position in FIG. 3 ) to an operating position (position on the right of the position in FIG. 3 by a predetermined length) in a forward drive state in which the electric motor 21 rotates forward, and can axially move the rod 22 e from the operating position to the return position in a reverse drive state in which the electric motor 21 reversely rotates. [0046] The conversion mechanism 22 includes a pinion 22 a integrally disposed on a rotating shaft 21 a of the electric motor 21 , a first intermediate gear 22 b 1 and a second intermediate gear 22 b 2 which are rotationally driven with the pinion 22 a , an output gear 22 c rotationally driven with the second intermediate gear 22 b 2 , a screw mechanism 22 d disposed at the center (center of axis) of the output gear 22 c , and the rod 22 e coupled to the output gear 22 c through the screw mechanism 22 d . The first intermediate gear 22 b 1 and the second intermediate gear 22 b 2 decrease rotation of the rotating shaft 21 a to transmit the rotation to the output gear 22 c. [0047] The first intermediate gear 22 b 1 , the second intermediate gear 22 b 2 , and the output gear 22 c are rotatably assembled in a housing 22 g . A thrust bearing 22 h which receives reaction force (force to the left in FIG. 3 ) from the parking lever 17 is assembled between the output gear 22 c and the housing 22 g . The output gear 22 c is configured to be able to move in an axial direction with reference to the housing 22 g . The electric motor 21 and the housing 22 g are fixed to the back plate 11 by using a fixture (not shown). [0048] The screw mechanism 22 d includes a female screw part formed at the center (center of axis) of the output gear 22 c and a male screw part formed from an intermediate part of the rod 22 e to the right end thereof, and the female screw part and the male screw part are meshed with each other. In the screw mechanism 22 d , when axial movement (movement to the left in the drawing) of the output gear 22 c is regulated, rotation (rotational motion) of the output gear 22 c is converted into axial movement (linear motion) of the rod 22 e . When axial movement (movement to the left in the drawing) of the rod 22 e is regulated by the stopper 27 , rotation (rotational motion) of the output gear 22 c is converted into axial movement of the output gear 22 c. [0049] In the screw mechanism 22 d , leads of the female screw part and the male screw parts are arbitrarily set, and the output gear 22 c is set not to be rotated by reaction force (axial force) from the parking lever 17 . The male screw part formed on the rod 22 e is covered and protected with a boot 22 j disposed between the distal-end part (left-end part) of the rod 22 e and the housing 22 g . The boot 22 j is configured to extend and contract with the axial movement of the rod 22 e. [0050] The stopper 27 and the disk spring assembly 28 which function as the load applying mechanism are designed to function after the parking lever 17 moves from the operating position to the return position, and the stopper 27 is fixed to the back plate 11 by using a fixture (not shown). The stopper 27 , after the parking lever 17 moves from the operating position to the return position, as shown FIG. 3 , is engaged with a first coupling pin 29 a of the coupling mechanism 29 to regulate axial movement of the rod 22 e in a return direction (to the left in the drawing). [0051] By reverse rotation of the output gear 22 c with reverse rotation of the electric motor 21 , after the parking lever 17 moves from the operating position to the return position, in a state in which the first coupling pin 29 a is engaged with the stopper 27 to regulate the axial movement of the rod 22 e with the stopper 27 , when the output gear 22 c moves from the return position in an operating direction (to the right in the drawing) in FIG. 3 with the reverse rotation of the output gear 22 c , the disk spring assembly 28 is engaged with the right end of the output gear 22 c to elastically regulate the axial movement (movement to the right) of the output gear 22 c so as to apply a rotational load to the output gear 22 c . The rotational load described above increases depending on a drive amount (axial movement) of the output gear 22 c , and the rotational load applied to the electric motor 21 increases accordingly. [0052] The disk spring assembly 28 , in the housing 22 g , is disposed coaxially with the output gear 22 c between the housing 22 g and the right end of the output gear 22 c . The disk spring assembly 28 includes a holder 28 a , three disk springs 28 b , and a thrust plate 28 c . The holder 28 a is to movably support the three disk springs 28 b and the thrust plate 28 c in a small-diameter cylindrical part, is disposed coaxially with the output gear 22 c , and is fixed to the housing 22 g in a large-diameter part. [0053] The three disk springs 28 b are disposed between the large-diameter part of the holder 28 a and the thrust plate 28 c alternatively as shown in the drawing (such that the large-diameter parts contact with each other and the small-diameter parts contact with each other), and are almost freely disposed in the illustrated state. The thrust plate 28 c is disposed between the disk spring 28 b at the left end in the drawing and the right end of the output gear 22 c , and can rotatably bear the right end of the output gear 22 c . The thrust plate 28 c , at the position in FIG. 3 , is fixed to the small-diameter cylindrical part of the holder 28 a not to be removed therefrom (not to move to the left). [0054] The coupling mechanism 29 , as shown in FIGS. 3 and 4 , includes the first coupling pin 29 a , a second coupling pin 29 b , and one pair of coupling plates (coupling members) 29 c . The first coupling pin 29 a is assembled on a distal end (end part) of the rod 22 e , orthogonal to the rod 22 e , and disposed in parallel with the pin (support shaft) 17 a of the parking lever 17 . An intermediate part of the first coupling pin 29 a is integrally fitted and fixed to an attaching hole 22 e 1 formed in the distal end (end part) of the rod 22 e . Both the end parts of the first coupling pin 29 a are assembled on first hole parts 29 c 1 each having an oval shape and formed in the coupling plates 29 c such that both the end parts can relatively rotate and move in a long-diameter direction (left-right direction in FIG. 3 and FIG. 4 ). When the rod 22 e returns and moves to the return position, as shown in FIG. 3 , both the end parts of the first coupling pin 29 a are set to be able to contact with the stopper 27 . [0055] The second coupling pin 29 b is assembled on a swinging end part 17 c of the parking lever 17 and disposed in parallel with the first coupling pin 29 a . The second coupling pin 29 b is relatively rotatably assembled on a circular assembling hole 17 c 1 formed in the swinging end part 17 c at the intermediate part and relatively rotatably assembled on circular second hole parts 29 c 2 formed in coupling plates 29 c at both the end parts. The second coupling pin 29 b has both ends each having a diameter larger than that of the intermediate part to prevent the second coupling pin 29 b from being removed. [0056] Each of the coupling plates 29 c can rotate in a first hole part 29 c 1 assembled in the first coupling pin 29 a in the circumferential direction of the first coupling pin 29 a with reference to the end part of the rod 22 e , can rotate in the second hole part 29 c 2 assembled in the second coupling pin 29 b in the circumferential direction of the second coupling pin 29 c 2 with reference to the parking lever 17 , and couples the first coupling pin 29 a and the second coupling pin 29 b to each other. [0057] In the configuration, on the parking lever 17 and the rod 22 e coupled by the coupling mechanism 29 , a swinging surface of the parking lever 17 and an axial line of the rod 22 e are disposed on the same plane. For this reason, in the embodiment, driving force of the electric actuator 20 can be smoothly transmitted to the swinging end part 17 c of the parking lever 17 . [0058] The motor control unit (electric control device) ECU, for example, has a function of stopping an operation (forward rotational drive) of the electric motor 21 when a rotational load reaches a set value (obtained by moving the parking lever 17 to the operating position) in a forward rotational drive state of the electric motor 21 , and a function of stopping an operation (reversely rotational drive) of the electric motor 21 when the rotational load reaches a predetermined value in a reversely rotational drive state of the electric motor 21 . [0059] The motor control unit (electric control device) ECU is configured such that the motor control device ECU is also connected to a parking lock switch SW 1 and a parking release switch SW 2 (when any one of the switches is turned on, the other is turned off) which are disposed in the driver seat of the vehicle (see FIG. 3 ), and, as shown in FIG. 5 , when the parking lock switch SW 1 is turned on in a state in which a parking brake release state (release state) is stored, a lock control process in step 100 and an end process in step 99 are executed to end the program. When the parking release switch SW 2 is turned on in a state in which a parking brake operating state (lock state) is stored, a release control process in step 200 and the end process in step 99 are executed to end the program. The release state is configured to be stored when the reversely rotational drive of the electric motor 21 is normally completed, and the lock state is configured to be stored when the forward rotational drive of the electric motor 21 is normally completed. [0060] When the motor control unit (electric control device) ECU executes the lock control process in step 100 in FIG. 5 , a lock control process routine in FIG. 6 is executed. In the lock control process routine in FIG. 6 , the process is started in step 101 , forward rotational drive of the electric motor 21 is started in step 102 , and an elapsed time T is counted up (Tup) in step 103 . In step 104 , it is determined whether the elapsed time T is a predetermined value T1 or longer. The predetermined value T1 corresponds to a time required until a current supplied to the electric motor 21 at the beginning of the forward rotational drive of the electric motor 21 becomes stable, and steps 103 and 104 are repeatedly executed until the elapsed time T reaches the predetermined value T1. [0061] In this manner, when the elapsed time T reaches the predetermined value T1, step 105 is executed to determines whether a current value A (This is calculated on the basis of an output from the current monitor IM.) supplied to the electric motor 21 is a target current value A1 or more. The target current value A1 is obtained when the parking lever 17 moves from the return position to the operating position to make a rotational load (load obtained when the brake shoes 12 and 13 move to the operating positions to bring the linings 12 a and 13 a into press contact with the brake drum) obtained by the forward rotational drive of the electric motor 21 becomes a set value, and steps 105 and 106 are repeatedly executed until the current value A reaches the target current value A1. In step 106 , a condition establishment duration Ta is reset. [0062] When the current value A reaches the target current value A1, steps 107 and 108 are executed to determine whether the condition establishment duration Ta is a predetermined value T2 or more. The predetermined value T2 is to determine a stop timing of the electric motor 21 , and is arbitrarily set. Steps 105 , 107 , and 108 are repeatedly executed until the condition establishment duration Ta reaches the predetermined value T2. When the condition establishment duration Ta reaches the predetermined value T2, “Yes” is determined in step 108 , steps 109 to 112 are executed to return the ECU to the main routine in FIG. 5 . The forward rotational drive of the electric motor 21 is stopped in step 109 , the lock state is stored in step 110 , and the elapsed time T and the condition establishment duration Ta are reset in step 111 . In step 112 , the return process is performed to end the program in step 99 in FIG. 5 . [0063] On the other hand, when the motor control unit (electric control device) ECU executes the release control process in step 200 in FIG. 5 , a release control process routine in FIG. 7 is executed. In the release control process routine in FIG. 7 , the process is started in step 201 , reversely rotational drive of the electric motor 21 is started in step 202 , and the elapsed time T is counted up in step 203 . In step 204 , it is determined whether the elapsed time T is a predetermined value T3 or longer. The predetermined value T3 corresponds to a time required until a current supplied to the electric motor 21 at the beginning of the reversely rotational drive of the electric motor 21 becomes stable (see T3 in FIG. 10 ), and steps 203 and 204 are repeatedly executed until the elapsed time T reaches the predetermined value T3. [0064] In this manner, when the elapsed time T reaches the predetermined value T3, step 205 is executed to determine whether the current value A supplied to the electric motor 21 is an abnormality determination current value A2 or more. The abnormality determination current value A2, for example, is obtained when rotational load obtained by the reversely rotational drive of the electric motor 21 is an abnormal value (see a virtual line and A2 in FIG. 10 ) when the parking lever 17 moves from the operating position to the return position (for example, an abnormally high rotational resistance is generated on the screw mechanism 22 d of the conversion mechanism 22 ). At this time, “Yes” is determined in step 205 to execute an in-abnormal-state process in step 210 . [0065] When the motor control unit (electric control device) ECU executes the in-abnormal-state process in step 210 in FIG. 7 , an in-abnormal-state process routine in FIG. 8 is executed. In the in-abnormal-state process routine in FIG. 8 , the process is started in step 211 , and an abnormal condition establishment duration Tb is counted up (Tbup) in step 212 . In step 213 , it is determined whether the abnormal condition establishment duration Tb is a predetermined value T4 or more. The predetermined value T4 is to determine a stop timing of the electric motor 21 (see T4 in FIG. 10 ), and is arbitrarily set. Until the abnormal condition establishment duration Tb reaches the predetermined value T4, “No” is determined in step 213 , and step 205 in FIG. 7 and steps 211 to 213 in FIG. 8 are repeatedly executed. [0066] When the abnormal condition establishment duration Tb reaches the predetermined value T4, “Yes” is determined in step 213 , and steps 214 to 217 are executed. The electric motor 21 is stopped in step 214 , an alarm for abnormality is generated in step 215 , and the elapsed time T and the abnormal condition establishment duration Tb are reset in step 215 . In step 217 , the return process is performed to end the program in step 99 in FIG. 5 . [0067] In a period in which the elapsed time T falls within the range of the predetermined value T3 to a set value T5, when the current value A supplied to the electric motor 21 does not increase not to reach the abnormality determination current value A2 (more specifically, as indicated by a solid line or a broken line in FIG. 10 , when the electric motor 21 normally operates), steps 205 to 208 in FIG. 7 are repeatedly executed. “No” is determined in step 205 , the elapsed time T is counted up in step 206 , the abnormal condition establishment duration Tb is reset in step 207 , and “No” is determined in step 208 . The set value T5 is set on the basis of a time required when the parking lever 17 moves from the operating position to the return position by normal reversely rotational drive of the electric motor 21 . [0068] In this manner, when the elapsed time T reaches the set value T5, “Yes” is determined in step 208 in FIG. 7 , and an in-normal-state process is executed in step 220 . When the motor control unit (electric control device) ECU executes the in-normal-state process in step 220 in FIG. 7 , an in-normal-state process routine in FIG. 9 is executed. In the in-normal-state process routine in FIG. 9 , the process is started in step 221 , a no-load current value Ao is calculated in step 222 , and it is determined in step 223 whether the current value A supplied to the electric motor 21 is a load determination current value (Ao+A3) or more. The no-load current value Ao is a current value supplied to the electric motor 21 before the first coupling pin 29 a is brought into contact with the stopper 27 by the reversely rotational drive of the electric motor 21 (more specifically, in a no-load state set until the first coupling pin 29 a contacts with the stopper 27 after the elapsed time T becomes the set value T5). A predetermined value A3 corresponds to a current value increasing depending on an increase in load obtained by the load applying mechanism (the stopper 27 and the disk spring assembly 28 ), and is arbitrarily set. Until the current value A reaches the load determination current value (Ao+A3), “No” is determined in step 223 , and steps 223 to 229 in FIG. 9 are repeatedly executed. In step 229 , a load condition establishment duration Tc is reset. [0069] Until the current value A reaches the load determination current value (Ao+A3), “Yes” is determined in step 223 , and steps 224 to 225 are executed. The load condition establishment duration Tc is counted up in step 224 (Tcup), and it is determined in step 225 whether the load condition establishment duration Tc is a predetermined value T6 or more. The predetermined value T6 is to determine a stop timing of the electric motor 21 (see T6 in FIG. 10 ), and is arbitrarily set. Until the load condition establishment duration Tc reaches the predetermined value T6, “No” is determined in step 225 , and steps 223 to 225 are repeatedly executed. [0070] When the load condition establishment duration Tc reaches the predetermined value T6, “Yes” is determined in step 225 , steps 226 to 228 are executed. The reversely rotational drive of the electric motor 21 is stopped in step 226 , the release state is stored and the elapsed time T and the load condition establishment duration Tc are reset in step 227 , and the return process is performed in step 228 to end the program in step 99 in FIG. 5 . [0071] In the embodiment described above, although the determination is made by setting the durations Ta, Tb, and Tc to avoid an erroneous determination caused by signal noise or the like, the determination can also be made without setting the durations Ta, Tb, and Tc (executed such that, after T becomes T1, the forward rotational drive of the electric motor 21 is stopped when A reaches A1, the reversely rotational drive of the electric motor 21 is stopped when T is T3 to T5 and A reaches A2, and the reversely rotational drive of the electric motor 21 is stopped after T becomes T5 and when A reaches (Ao+A4)). [0072] As described above, in short, in the embodiment, in the electric parking brake device according to the present invention, the operation/stop of the electric motor 21 can be advantageously controlled by a current value A supplied to the electric motor 21 (a sensor for electrically detecting the state of the parking lever 17 is advantageously unnecessary), and the motor control unit (electric control device) ECU can be simply configured at low costs. Since the motor control unit (electric control device) ECU includes the calculation unit (steps 222 and 223 ) and the reversely rotational drive stop unit (steps 223 to 226 ) and is configured to stop the reversely rotational drive of the electric motor 21 when it is determined that the rotational load determination value (current value A) is the reference value (Ao+A3) or more the set time after the reversely rotational drive of the electric motor 21 is started (T=0) (T≧T5), the reversely rotational drive of the electric motor 21 can be accurately stopped, and a rotational load required for the load applying mechanism (the stopper 27 and the disk spring assembly 28 ) can be set to be small. As a result, the load applying mechanism (the stopper 27 and the disk spring assembly 28 ) can be miniaturized and manufactured at low costs. [0073] In the embodiment, the sum (Ao+A3) of the no-load current value Ao and the preset predetermined current value A3 is defined as a reference value for reversely rotational drive stop determination of the electric motor 21 , and the no-load current value Ao serves as a part of the reference value. For this reason, a fluctuation in performance caused by a manufacturing error or the like in the conversion mechanism 22 or the load applying mechanism (the stopper 27 and the disk spring assembly 28 ) can be excluded. Thus, determination accuracy when the reversely rotational drive of the electric motor 21 is stopped can be improved, and a rotational load required by the load applying mechanism (the stopper 27 and the disk spring assembly 28 ) can be reduced. As a result, the load applying mechanism (the stopper 27 and the disk spring assembly 28 ) can be miniaturized and manufactured at low costs. [0074] In the embodiment, when it is determined that the rotational load determination value (current value A) is the reference value (A2) or more within the set time (time zone from T3 to T5) except for an operation initial time zone (time zone from 0 to T3) in which a current is unstable from the start of the reversely rotational drive (T=0) of the electric motor 21 , the abnormal-state reversely rotational drive stop unit (step 214 ) for stopping the reversely rotational drive of the electric motor 21 and the abnormality notification unit (step 215 ) for notifying of abnormality are included in the motor control unit (electric control device) ECU. For this reason, abnormality in the electric actuator 20 in the device is detected to make it possible to stop an abnormal operation and to notify of the abnormal operation. [0075] In the embodiment, the program is executed such that the sum (Ao+A3) of the no-load current value Ao and the preset predetermined current value A3 is defined as the reference value for determining a timing of stopping the reversely rotational drive of the electric motor 21 and the current value A supplied to the electric motor 21 is defined as the rotational load determination value. However, in execution of the present invention, a differential value of the current value A supplied to the electric motor 21 may be employed as the rotational load determination value. In this case, the stop timing can be determined rapidly more than that in the embodiment, determination accuracy at which the reversely rotational drive of the electric motor 21 is stopped can be improved, and the load applying mechanism can be further miniaturized and manufactured at low costs. [0076] In the embodiment, the determination is made such that the sum (Ao+A3) of the no-load current value Ao and the preset predetermined current value A3 is defined as the reference value for determining a timing of stopping the reversely rotational drive of the electric motor 21 and the current value A supplied to the electric motor 21 is defined as the rotational load determination value. However, in execution of the present invention, the determination can also be made such that the set value A4 (see FIG. 10 ) larger than (Ao+A3) is employed as the reference value. [0077] In the embodiment, an abnormality determination is made by the current value A supplied to the electric motor 21 . However, for example, the abnormality determination can also be made by a differential value of the current value A supplied to the electric motor 21 , and various changes can be effected without departing from the contents described in the scope of claims.

Electric parking brake devices are configured such that a parking lever is driven by an electric actuator. The electric actuator is provided with: an electric motor drivable in a forward/reverse direction and operationally controlled by a motor control unit according to rotational loads; a conversion mechanism capable of converting a rotational motion into a linear motion, moving the parking lever from a return position toward an operating position through forward rotation of the electric motor, and moving the parking lever from the operating position toward the return position through the reverse rotation of the electric motor; and a load applying mechanism (a stopper and a disc spring assembly) for applying a predetermined rotational load to the electric motor by driving a constituent member of the conversion mechanism after the parking lever is moved from the operating position to the return position through the reverse rotation of the electric motor.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to molecular biology and clinical diagnostics, specifically to methods, devices, and compositions for fractionation and processing of microparticles from biological samples, and to methods for obtaining and using the microparticles for biomarker discovery. Biological samples include cell-free fluids, for example blood plasma, blood serum, cerebrospinal fluid, urine, and saliva, as well as conditioned media. Conditioned media is the liquid growth media used to propagate cells in vitro. Purification of microparticles from cell-free fluids is challenging, typically accomplished by prolonged ultracentrifugation. We have developed an alternative method for efficiently harvesting and processing microparticles from cell-free fluids and from conditioned media. The invention also generally relates to use of the microparticles and their contents recovered from conditioned media derived from propagation of human and animal cells, as a source of biomarkers for diagnosis and prognosis of diseases and pathological conditions. [0003] 2. Description of the Relevant Art [0004] There is a growing appreciation of the biological role of different types of membrane-bound microparticles (MPs) shed by cells and tissues. As used in this application, the term “microparticles” refers to all types of membrane-bound particles released by cells and platelets, including microvesicles, microparticles, tumor microvesicles, exosomes, ectosomes, platelet dust, apoptotic bodies, etc. These particles, which may be roughly spherical or irregular in shape, differ according to size and origin, for example apoptotic bodies range in size from one to several micrometers and are shed from cells undergoing apoptosis (the process of “programmed cell death”), while microvesicles, which are smaller than 1 μm, are thought to bud off directly from the plasma membrane of healthy cells. Exosomes are even smaller, on the order of 30-100 nanometers (nm), and are released from multivesicular bodies by the process of exocytosis. The distinction between different types of MPs is not always clear. For example the term apoptotic bodies has been used synonymously with microparticles. [0005] MPs contain integral membrane proteins reflecting their cells of origin, and bioactive molecules including mRNA, microRNA and proteins. Many recent publications describe between-cell delivery of biological signals mediated by proteins and RNA contained in MPs (see above references). MPs are thought to be produced by all or most types of cells and tissues. MPs shed from cells and solid tissues can enter the circulation and occur in cell-free fluids, for example in the non-cellular fraction of blood known as plasma or serum. MPs are also shed in abundance into conditioned media, which is the media used to propagate cells in vitro, including eukaryotic and prokaryotic cells, mammalian cells, and especially including human cells. Large quantities of MPs are shed into conditioned media from malignant cells, from which the shedding of MPs may be increased compared to non-malignant cells. MPs shed from tumors may enter the circulation and mediate growth of tumors, for example by inducing growth of blood vessels that deliver nutrients to support tumor growth. MPs detected in the circulating blood of cancer patients are potential sources of diagnostic and prognostic biomarkers. Current research is focused on gaining a better understanding of the role of MPs in delivery of biological signals between cells and tissues, in both disease and health, and in identifying MP-based biomarkers. Improved methods for concentrating MPs from conditioned media and from cell-free body fluids will allow samples to be processed more rapidly and at a lower cost. This will permit detection of low-abundance MP-derived analytes, including RNAs and proteins, and increase the sensitivity of assays aimed at quantitative detection of MPs for clinical purposes, including biomarker discovery. The term “biomarkers” refers to molecules of biological origin (for example RNA, DNA, and proteins) derived from patient samples, whose levels have diagnostic and/or prognostic value. [0006] A limitation in MP-based research is that current methods for recovering these particles from the relatively large volumes of fluids in which they occur, are laborious, time-consuming, and require expensive specialized equipment. The currently used methods for concentrating MPs from blood or culture media involve sequential centrifugation of liquid samples at increasing relative centrifugal force (rcf) to first remove intact cells and larger cell fragments and debris by low-speed centrifugation, followed by centrifugation at higher rcf to pellet the particles of interest. The rcf used to recover particles varies according to their size. For example, in one study, conditioned media was centrifuged for 10 min at 800×g to remove dead cells and cell debris, then further centrifuged for 20 min at 16,000×g to pellet the relatively large apoptotic bodies. In another study, microvesicles shed by cultured tumor cells were isolated by centrifuging the culture media for 30 min at 2,000 rpm to remove cell debris, followed by centrifugation at 20,000 rpm for 2 hours to pellet the MPs. To recover smaller particles, even higher ref is required, for example one study showed that for isolation of microvesicles it is widely accepted that ultracentrifugation should be performed at 100,000×g from 20-60 minutes and that in order to recover MPs smaller than 100 nm (the so-called exosomes), sucrose gradient ultracentrifugation is required. [0007] Concentrating MPs by centrifugation requires expensive equipment. For example Beckman ultracentrifuges retail for around $60,000-$70,000 and the rotors required for their use list for $20,000-$23,000. Such equipment is not routinely available, especially in clinical labs and small research labs. These considerations argue for the need for better methods to facilitate processing of liquid samples to purify MPs. Once this hurdle has been passed, rapid gains can be expected in basic and applied research needed to exploit the use of MPs for therapeutic and diagnostic applications. The invention described herein overcomes the requirement for sequential centrifugation and for ultracentrifugation to purify MPs. The invention further describes the use of MPs from conditioned media for discovery of biomarkers. The biomarkers will enable use of MPs produced by patient cells propagated in vitro for improved diagnosis and treatment of disease. [0008] Several research groups have reported identification of candidate biomarkers in RNA, microRNA, or proteins extracted from MPs present in human cell-free bodily fluids, especially blood plasma and serum. However, size-fractionated MPs recovered from conditioned media from patients' cultured cells have not been described as source of biomarkers. A major technical advantage of identifying RNA biomarkers in MPs compared to using solid tissues or circulating blood cells or cells cultured in vitro as the source tissue, is that RNA in MPs is expected to be much more stable in the transcriptionally inactive particles shed from cells (MPs), compared to their status in metabolically active tissues and cells, where rapid up-and down-regulation of specific RNA levels has been well-documented. Also, RNA in MPs is protected from the nucleases present in high concentrations in conditioned media and in cell-free body fluids such as blood plasma and urine. The potential of MPs to serve as biomarkers and potentially also as therapeutic agents will require considerable basic research followed by major development efforts to translate new findings into clinical assays and products. An important first step toward this goal is to create methods that allow rapid, economical, high-yield purification of MPs and their contents, especially RNA and proteins. [0009] In light of the above considerations and notwithstanding the acknowledged ambiguity in the nomenclature used to describe the various types and origins of cell-derived microparticles, it can be reasonably concluded that MPs can be classified according to size into at least 3 categories: a. MPs greater than approximately 1 micron in diameter (for example apoptotic bodies); b. MPs smaller than 1 micron but larger than approximately 0.1 micron in diameter (for example microvesicles); c. MPs smaller than 0.1 micron in diameter (for example exosomes); and further, that MPs can be fractionated from fluids containing mixtures of different types of MPs by sequential centrifugation of the fluids at increasing centrifugal forces of approximately 800-2,000×g, 16,000-20,000×g, and 80,000-100,000×g. Further, MPs can be recovered from primary and long-term in vitro cultures of mammalian cells, including human cells. “Primary” cell cultures are those in which the cells originated from living tissues removed from an animal, whereas long-term cultures relate to populations of cells surviving after the primary culture has been “passaged” many times. “Passaging” cultured cells means removing a subset of growing cells, typically along with some of the conditioned media in which they have been growing, and transferring them to a new vessel, along with fresh culture media; after transfer, the cells continue to grow and divide (a process known as “expansion”). Typically, after a set number of passages, many of the primary cells and their progeny undergo the process of senescence, meaning they fail to continue to divide; however, a relatively few minority of cells may survive senescence and continue to grow and divide, thus establishing a long-term immortal cell line derived from a particular primary culture. Examples of tissues used as source of primary cells for in vitro culture are cells from solid tumors or malignancies of the blood, as well as healthy tissues including blood, endothelial cells, skin fibroblasts, epithelial tissue, etc. [0010] MPs isolated from conditioned media from primary and/or long-term culture of a patient's cells have potential to serve as source of biomarkers. When the primary cells are pathological in origin, the MPs may serve as a source for clinically useful biomarkers for diagnosis and/or treatment of the pathological condition, for example, malignancy. It is contemplated that MPs can be harvested from conditioned media obtained from primary and/or long-term culture of an individual's cells, and that contents of the MPs, including RNA, microRNA, and proteins, can be extracted from the MPs to provide clinically useful information. It is further contemplated that the information content of the MPs will be more useful when the naturally occurring heterogeneous mixtures of MPs are first fractionated according to size, prior to extracting their contents for analysis. It is further contemplated that analysis of contents of MPs fractionated according to size will improve the ability to discover MP-derived biomarkers and apply them for clinical use. [0011] Many experimental approaches are contemplated for biomarker discovery and use in MPs obtained from conditioned media. One approach is comparison of the levels of biomolecules in MPs derived from patient samples, with the levels of the same biomolecules derived from healthy individuals. Another approach is investigation of MP content in temporal space, which may itself consist of at least 2 types. One type of temporal analysis is analysis of MPs from conditioned media collected over a time-course, for example collected after shorter and longer periods of culture of primary cells derived from a patient's tumor. Another type of temporal analysis is analysis of MPs from primary cells obtained from tissues harvested sequentially at different times during the course of disease, for example from a needle biopsy of a newly-diagnosed malignancy and from a subsequent biopsy of a tumor from the same patient after treatment. Analysis of sequential MP samples from conditioned media samples obtained over temporal space is expected to lead to identification of associative patterns that can be developed into clinically useful biomarkers. Another approach for biomarker discovery in MPs harvested from conditioned media is to compare contents of MPs recovered from cells of different lineages, for example malignant tumor cells, endothelial cells, or blood leukocytes, that may grow out of a single tissue isolate. Yet another approach for MP-based biomarker discovery and use is to analyze MPs recovered from experimentally treated cells, for example cells treated to induce apoptosis. One of the most straightforward treatments of cultured cells to induce apoptosis is to grow them under “serum starvation” conditions, that is, in media from which the usual component of fetal bovine serum (typically added to basic liquid growth media to a level of ˜10%-20%) is withheld. These approaches are not mutually exclusive and can be combined. For example, one could carry out temporal analysis of MPs recovered from conditioned media from treated cells of several lineages derived from a single tumor. For all of these approaches, the promise of identifying new biomarkers for clinical use will be more easily realized by using size-fractionated MPs, rather than using complex mixtures of MPs of divergent sizes (which reflect their divergent biological origins). Better methods to fractionate and process conditioned media-derived MPs will facilitate MP-related basic research, leading to significant clinical benefits. The present disclosure overcomes current limitations in obtaining and processing size-fractionated MPs from heterogeneous samples. SUMMARY OF THE INVENTION [0012] In one embodiment, a method for concentrating and fractionating microparticles according to their size from a liquid sample, comprises passing the sample sequentially through at least two filters having different pore sizes, wherein said filters are effective to trap membrane-bound particles of different sizes from the liquid sample. The filters may be contained in devices having inlet and outlet ports such that the devices can be attached to each other and to standard syringe(s). One or more of the filters may include a pre-filter effective to remove debris from the liquid sample which could otherwise interfere with entrapment of the membrane-bound particles. [0013] In one embodiment, a sample is passed through a first filter having a pore size effective to trap larger particles from the liquid sample, and subsequently passed through one or more additional filters having pore size(s) effective to trap particles smaller than the larger particles from the liquid sample. The first filter may have has a pore size of about 200 nanometers (nm) and one or more of the additional filter has a pore size of about 20 nm. In another embodiment, the first filter has a pore size of about 700 nm-1,000 nm, a second filter has a pore size of about 200 nanometers (nm), and a third filter has a pore size of about 20 nm. [0014] In an embodiment, the filters are attached to each other prior to passing the liquid sample through them, such that the sample passes through a first filter and then through one of more additional filters. The filters may be separated after passing the liquid sample through them. The separated filters with trapped particles may be processed to extract the contents of the particles. In one embodiment, the process of extracting the contents of the particles includes: passing a reagent through the separated filters, said reagent having a composition effective to disrupt the membranes of the trapped particles, thereby forming a particle lysate; collecting the particle lysate; and treating the particle lysate in a manner to purify and concentrate one or more biological components present in said lysate. Biological components that may be extracted include RNA, DNS, proteins, or combinations thereof. [0015] In one embodiment, a method for identifying biomarkers having clinical utility for diagnosis and/or treatment of disease includes: obtaining two or more samples of tissue or cells; treating and maintaining the samples under conditions effective to allow in vitro propagation of cells in said samples in a liquid medium; recovering the liquid medium used to propagate the cells from the samples; processing the liquid medium from the samples using filters to recover membrane-bound particles present in the samples; purifying one or more biological components from particles retained on the filters from the samples; determining the levels of one or more purified biological components from the samples; comparing the levels of one or more of the purified biological components recovered from one or more samples between said samples; and determining associations between compared levels of one or more of the purified biological components recovered from one or more samples, where said associations have correlations with different physiological conditions in the one or more samples. The biological component being compared may be RNA (e.g., microRNA), DNA, proteins, or combinations thereof. [0016] In one embodiment, a method for obtaining diagnostic or prognostic information for clinical use includes: obtaining a sample of tissue or cells from an individual; treating and maintaining the sample under conditions effective to allow in vitro propagation of cells in said samples in a liquid medium; recovering the liquid medium used to propagate the cells from the sample; processing the liquid medium from the sample using filters to recover membrane-bound particles present in the samples; purifying one or more biological components from particles retained on the filter from the sample; determining the levels of one or more purified biological components from the sample; and analyzing the levels of one or more of the purified biological components recovered from the sample to determine associations between said levels and known expected values of said components, said analysis effective to provide prognostic or diagnostic information relevant to the individual. [0017] In one embodiment, a method for obtaining diagnostic or prognostic information for clinical use includes: obtaining a sample of cell-free bodily fluid from an individual; processing the fluid using filters to recover membrane-bound particles present in the fluid; purifying one or more biological components from particles retained on the filter from the sample; determining the levels of one or more purified biological components from the sample; and analyzing the levels of one or more of the purified biological components recovered from the sample to determine associations between said levels and known expected values of said components, said analysis effective to provide prognostic or diagnostic information relevant to the individual. [0018] In one embodiment, a kit for fractionating MPs from biological samples, includes one or more filters and devices effective to capture said MPs from the samples, and optionally also comprising reagents for extracting, concentrating, and purifying the contents of said MPs. [0019] In one embodiment, a method for preparing lipids and/or lipid-containing material from MPs includes: concentrating and fractionating microparticles according to their size from a liquid sample; treating the fractionated microparticles with reagent(s) effective to disrupt and solubilize their membranes; and recovering the disrupted and solubilized membrane components. The disrupted and solubilized membrane components may be further purified by treatment with nucleases and/or proteases and/or treated to remove solvents or detergents. BRIEF DESCRIPTION OF THE DRAWINGS [0020] Advantages of the present invention will become apparent to those skilled in the art with the benefit of the following detailed description of embodiments and upon reference to the accompanying drawings in which: [0021] FIG. 1 depicts an analysis of RNA extracted from MPs trapped on filters. [0022] While the invention may be susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. The drawings may not be to scale. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but to the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0023] It is to be understood the present invention is not limited to particular devices or biological systems, which may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include singular and plural referents unless the content clearly dictates otherwise. [0024] Described herein are methods, devices and reagents for fractionating and purifying microparticles (MPs) and their contents from biological samples. A primary feature of the embodiments described herein are the use of a series of filters having suitable properties for trapping MPs of different sizes from biological samples, and devices to allow use of such filters for recovering MPs from biological samples. Examples of biological samples that may be used with said filters and devices are blood serum and blood plasma from humans and other mammalian and non-mammalian animals, as well as conditioned media used to propagate cells in culture. The MPs captured on the filters may subsequently be recovered from the filters as intact particles, said particles having potential for use as delivery agents for transferring their contents to recipient cells. Contents of potential interest that may be transferred by intact MPs are proteins, chemicals, DNA, mRNAs, microRNAs, siRNAs, and other non-coding RNAs. [0025] As an alternative to recovering intact MPs from the filters for use as delivery agents, the MPs captured on the filters may be processed by disrupting the MPs and collecting their contents. Disruption of captured MPs may be accomplished by removing the filters along with the trapped MPs to a second vessel, for example a microfuge tube, and adding reagent(s) capable of disrupting the MP membrane and releasing its contents. Alternatively, recovery of the MP contents may be accomplished by in situ disruption of the MP's membranes without removing the filters from the device in which they are placed, for example by flushing the filters with reagent(s) effective to disrupt the captured MPs and release their contents into a separate vessel. Disruption of MPs can be accomplished by use of various reagents. For disruption of MPs and subsequent purification of their RNA and/or protein contents, single-phase reagents containing chaotropic agent(s) (such as guanidinium thiocyanate or guanidinium hydrochloride) and organic solvent (such as phenol) are especially useful. Alternative reagents such as those based on other denaturing chemicals such as urea, or on other nuclease-inactivating reagents such as proteases, may be used instead of single-phase reagents containing guanidinium and phenol. Other types of membrane-disrupting reagents familiar to those skilled in the art of molecular biology may also be used to disrupt the MPs. Further purification and concentration of the contents of disrupted MPs can be accomplished using a variety of different methods known to those skilled in the art, for example alcohol precipitation or solid-phase extraction onto silica matrices. An aspect of the process includes the use of reagents and protocols for further purifying and concentrating the contents of MPs trapped on filters. A further aspect of the process relates to use of biomolecules recovered from MPs released by cells, especially those grown in vitro, as a source for discovery of biomarkers and as source sample for use of said biomarkers for diagnosis and prognosis of pathological conditions. [0026] In addition to recovering and using the contents of disrupted MPs, it is contemplated that recovery of the lipid monomers and other lipid-containing materials originating from the disrupted membranes of MPs, may also be useful. Such lipids or lipid-containing materials could be recovered by solubilizing the MPs in solvents such as chloroform or by disrupting the MPs in reagents containing detergents. The solvents or detergents can then be removed, for example by evaporation or by chromatography, leaving the lipids and lipid-containing materials in a more concentrated foam. It is contemplated that such lipids and lipid-containing materials will be useful for preparing liposomes for delivery of natural or synthetic molecules, especially for clinical purposes. Examples of synthetic molecules that may be delivered by MP-derived liposomes and that have utility for clinical purposes are small interfering RNA molecules (siRNAs) and synthetic DNA molecules that may encode siRNAs, and recombinant viral vectors. Examples of natural molecules that may be delivered by MP-derived liposomes and that have utility for clinical purposes are plasmids, viruses, and antibodies. Natural and synthetic molecules may be incorporated into the liposome membranes and/or into the interior space of the liposomes. In cases where it is desirable to recover lipids or lipid-containing materials derived from membranes of MPs in a substantially pure form wherein the lipids or lipid-containing materials are not mixed with the contents of the MPs, the contents of the MPs can be removed or rendered inactive by disrupting the MPs, or by treating the material comprising disrupted MPs, with reagents containing nucleases, including DNases and RNases, and/or by treating or disrupting the MPs with reagents containing proteases. [0027] In one embodiment, a process uses filtration, instead of the currently used method of centrifugation, to directly capture MPs from liquid samples. In an embodiment, a series of two or more filters having different properties are used to allow entrapment of MPs of different sizes. Liquid samples containing mixtures of MPs that differ in their origin, sizes, and contents, may be recovered as separate populations for further analysis. In one embodiment, the filters are contained in plastic devices that provide support for the filters and that allow attachment of the filters to a reservoir that is used to contain the liquid sample prior to processing. An especially useful design for such devices is as so-called “syringe filters”, in which filters are placed over a perforated support to allow liquid to flow through the filter, and with the device having inlet and outlet ports designed such that the devices can be readily connected to each other and to standard syringes. The syringes can be of different sizes, ranging from less than 1 ml to 60 ml, to allow processing of samples of a wide range of volumes. For cases in which two or more syringe filter devices are connected to each other, they are connected such that the top filter, that is the filter in which the liquid sample is first contacted, has the largest effective pore size, enabling entrapment of the largest particles, and subsequent filters are in order of decreasing pore size, to enable successive entrapment of smaller and smaller particles. The top filter in a series of connected filters may have a pore size of >1 μM, effective to trap intact cells with minimal entrapment of smaller microparticles. To maximize recovery and size homogeneity of MPs, a liquid sample may be passed over a series of 2 or more filters, or over a single filter, and the “flow-through” liquid passing through the filter(s) may be recovered and passed once again over the same filter(s). After the liquid sample has been passed over a series of one or more filters, the filters are then disconnected and processed separately, to allow recovery of the size-fractionated MPs or their contents as separate preparations. [0028] In one process, filters are used to harvest MPs from cells grown in tissue culture. Different types of mammalian cells are known to naturally shed MPs into the culture media. As discussed above, these MPs can serve as a source of biomarkers. Those skilled in the art of molecular biology will also appreciate that primary cells or immortalized cell lines can be engineered, using methods known to those with skill in the art, to make MPs with useful RNA and/or protein content. [0029] The following examples are included to demonstrate preferred embodiments of the invention. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventor to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention. Example 1 Fractionation of Populations of Smaller and Larger MPs from Tissue Culture Media [0030] Conditioned media was obtained from several human cancer cell lines (A549 lung cancer, CLL lymphoma cells, and HL60 liver cancer cells) growing as adherent cells, that is, the cells were attached to the bottom of the culture vessels. Typical volumes of conditioned media from adherent cells range from about 5 ml-15 ml per 100 mm tissue culture dish. In general, the conditioned media may be loaded into a syringe of appropriate capacity for the volume of sample, by aspirating the media into the syringe. Syringe filters having pore sizes effective to trap MPs from the conditioned media are then attached to the outlet port of the syringe. Alternatively, the plunger of the syringe may be removed, the syringe filter(s) then attached, and the conditioned media then loaded by pouring it into the barrel of the syringe and then reinserting the plunger. In either case, the end result is a syringe containing the conditioned media, with the filter(s) attached. The latter option for loading the sample into a 12 ml syringe was used in this Example. [0031] The filters used in this Example consist of two syringe filters, each ˜25 mm in diameter, with the top filter having a pore size of ˜200 nanometers (0.2 microns), and the bottom filter having a pore size of ˜20 nanometers (0.02 microns). The syringe filters were obtained from Tisch Scientific (Village of Cleves, Ohio 45002, USA). The filter having a pore size of ˜200 nanometers was catalog #SF14499, and the filter having a pore size of ˜20 nanometers was catalog #SF15016. The syringe filter-syringe assembly was then positioned over a vessel to catch the flow-through. The plunger of the syringe was then gently depressed to apply the force needed to drive the media sample through the connected filters. After the sample had passed through the filters, they were removed from the syringe and then disconnected from each other. Residual media in the filter devices was removed by tapping the outlet ports of the devices on a paper towel. Each of the filter devices were separately processed by attaching each to a 6 ml syringe which had been preloaded with 1 ml of a single-phase reagent (BiooPure RNA Extraction Reagent, Bioo Scientific, Austin, Tex.) comprising phenol, guanidinium thiocyanate, and other components effective to disrupt cell membranes, including the membranes that delineate cellular MPs. The assemblies were positioned over 1.5 ml microcentrifuge tubes, and the plungers of the syringes slowly depressed to force the BiooPure reagent into the filter device. The assembly was tilted during delivery of the BiooPure reagent into the filter device, in order to maximize contact of the reagent with the surface of the filter. Contact of the reagent with the entire surface of the filter is confirmed visually, by presence of green color on the entire surface of the filter. Contact of the reagent with the trapped MPs causes their membranes to be disrupted, resulting in release of their contents. The plungers were then fully depressed to flush the reagent, along with the contents of the disrupted MPs, into 1.5 ml receiving tubes. The samples (lysates from size-fractionated MPs) were then mixed thoroughly by vortexing. Samples may be processed immediately to purify and concentrate the released contents of the MPs, or the samples may be stored for subsequent processing. In this Example, the samples were stored at −20 C. for several days prior to further processing. Example 2 Extraction of RNA from MPs Recovered from Conditioned Media [0032] Extraction of RNA from MPs was carried out using a proprietary reagent (BiooPure RNA Extraction Reagent) developed at Bioo Scientific, which is similar to Trizol (sold by Sigma and other vendors). Trizol has also been used for extraction of MPs captured from conditioned media on filters. Trizol and BiooPure are both single-phase reagents containing phenol and guanidinium, and the extraction protocols are similar. RNA was extracted by thawing the preparations (described in Example 1) and adding 0.1 ml of 1-bromo-3-chloropropane (purchased from Sigma Life Science Research products, cat #B9673), vortexing the prep for ˜20 sec, then centrifuging the prep in a microcentrifuge for ˜15 min at 4 C. The resulting separated aqueous phase (top phase) was transferred to a new 1.5 ml tube and mixed with 50 μg of linear polyacrylamide (Bioo Scientific), followed by mixing with 0.75 ml of isopropyl alcohol. The prep was stored at room temp for ˜15 min and then centrifuged for 15 min at 12,000 rpm at 4 C. The supernatant fluid was carefully removed and the pelleted material was washed by adding 0.6 ml of 75% ethanol (diluted in nuclease-free water), vortexing to dislodge the pellet, then re-centrifuging the prep for 10 min at 10,000 rpm at 4 C. The supernatant fluid was thoroughly removed and the pellet of RNA dissolved in 50 μL of 0.1 mM EDTA made in nuclease-free water. To aid solubilization, the prep was vortexed, then incubated for 5 min at 65 C. in a heat block, then re-vortexed and centrifuged briefly to collect all liquid at the bottom of the tube. The preparation was then stored at −20 C. until use. Example 3 Quantitative Detection of microRNAs in RNA Extracted from Size-Fractionated MPs Recovered from Conditioned Media [0033] Recovery of RNA from the MPs captured on filters from conditioned media was verified by using a commercially available microRNA-detection assay from Life Technologies Inc. This assay is based on reverse transcription followed by quantitative PCR(RT-qPCR). We have also used this assay to detect microRNA in preps from MPs recovered from human serum. [0034] The reverse transcription step was carried out in a 7.5 μL volume containing 2.5 μL of RNA prepared as described in Example 2 along with approximately 50 units of MMLV Reverse Transcriptase (Bioo Scientific), standard buffer components, and reverse transcription primers for several microRNAs (miR-150, miR-191, and miR-337), provided in the Life Technologies assays. Reactions were incubated according to the Life Technolgies protocol. For the qPCR step, 1.5 μL of each reverse transcription reaction was used as template for duplicate amplification reactions (“technical duplicates”) of 20 μL, using the microRNA target-specific amplification primers from the Life Technologies assay according to manufacturer's instructions. Reactions were carried out using a BioRad iQ real-time instrument and Ct values recorded. Ct stands for cycle threshold, the amplification cycle number at which a detectable fluorescent signal is generated over a preset background level; in this study the instrument default value was used for the background and detection settings. The lower the Ct value, the higher the abundance of target molecule in the sample (since the more abundant the target, the fewer PCR cycles are needed to amplify it to a detectable level). Due to the exponential nature of PCR, a difference of 3.32 Ct's corresponds to a ˜10-fold difference in target abundance (since 2̂3.32˜10). We observed the following data in this experiment: [0000] Sample RNA miR-150 Ct value miR-191 Ct value miR-337 Ct value RNA recovered from Technical duplicates: Technical duplicates: Technical duplicates: MPs trapped on top 29.76/29.69, 24.62/24.63 32.07/32.39 filter having larger avg = 29.72 Avg = 24.62 Avg = 32.23 pore size RNA recovered from Technical duplicates: Technical duplicates: Technical duplicates: MPs trapped on 28.22/27.91 27.69/26.63 31.81/31.95 bottom filter having Avg = 28.07 Avg = 27.16 Avg = 31.88 smaller pore size Negative control (no Not detected (Ct > 45) Not detected (Ct > 45) Not detected (Ct > 45) input cDNA in PCR step) This experiment demonstrates the effectiveness of the filters for concentrating microRNA from conditioned media. Since the relative levels of specific microRNAs in fractionated MPs obtained from conditioned media have not been reported previously, there is no basis for comparison of our results to those of others. However this experiment indicates that the filters trapped different populations of MPs, because the relative levels of the 3 microRNAs differed in the MPs trapped on the filter with larger pore size compared to the filter having smaller pore size. The level of miR-191 is ˜34-fold higher than miR-150 in MPs captured on the filter with larger pore size (2̂5.1), while the level of miR-191 is only ˜1.9 fold higher than miR-150 in MPs captured on the filter with smaller pore size (2̂0.91). Example 4 Fractionation and Processing of MPs from Human Serum [0035] Human blood serum was purchased from a commercial source (Innovative Research) and approximately 5 ml of serum from a single donor was fractionated over a filter having a 20 nm pore size as described in Example 1. The filter was then flushed with RNA extraction reagent to lyse the trapped particles as described in Example 2; the lysate was recovered and saved for RNA extraction. This sample is referred to as “Serum filter”. Prior to filtration, 0.25 ml of serum was removed and mixed with RNA extraction reagent as described in Example 2 (this sample is referred to as “pre-filtration serum”). After filtration, 0.25 ml of serum that had passed through the filter was removed and mixed with RNA extraction reagent (this sample is referred to as “flow-through serum”). RNA was then extracted from the 3 samples using the method described in Example 2, and the RNA from each sample was resuspended in an equal volume (30 μL) of 0.1 mM EDTA. Equal volumes of RNA recovered from each sample was used for detection of a microRNA, miR-191, as described in Example 3. The Ct values are shown below. [0000] Prefiltration serum Serum filter Flow-through serum Avg Ct miR-191: Avg Ct miR-191: Avg Ct miR-191: 32.31 27.83 34.01 [0036] The ability of the filter to concentrate RNA signal from human serum is verified by comparing the mir-191 signal in RNA extracted from unfractionated serum and in the flow-through sample, with the level in RNA extracted from purified MPs. The signal in the filter sample is approximately 22-fold greater than in the prefiltered sample (2̂4.48) and 73-fold greater than in the flow-through sample (2̂6.18). The flow-through sample is depleted from miR-191 signal by ˜3.2 fold compared to the prefiltration sample (2̂1.7). [0037] In the experiments described above, filters with captured MPs were processed by flushing them with RNA extraction reagent, which immediately disrupts the MN and stabilizes their RNA. While this procedure will be useful for serum biomarker discovery, for use as delivery vehicles, the MPs would need to be recovered as intact particles. A further embodiment is to recover intact MPs after their entrapment on filters. To recover intact MPs, the filters with MPs could be removed to vessels containing a physiological buffer such as PBS and vortexed to release the MPs, or the filters with trapped MPs could be back-flushed with a physiological buffer such as PBS to release the intact trapped particles. Example 5 Analysis of RNA from Conditioned Media on Agilent Bioanalyzer [0038] RNA was extracted as described in Example 2, from MPs trapped on filters from conditioned media and from the corresponding flow-through, and analyzed on an Agilent Bioanalyzer as shown in FIG. 1 . This instrument uses capillary electrophoresis to separate RNA samples according to size. In the electropherograms shown below, the concentration of RNA in the samples is reflected by the height of the peaks (the higher concentration, the higher the peak height) and the size of the RNA is reflected in the position of the peak along the X-axis (the larger the RNA, the further it migrates in the right-hand direction). The small “hump” seen in the lower left-hand corner of the electropherogram traces in Samples 7, 8, 9, and 10 in the FIG. 2 is the RNA recovered from MPs trapped on 20 nanometer filters from 4 different conditioned media samples. Samples 11, 12, 13, and 14 show material extracted from the corresponding flow-through conditioned media. The lack of the peak in Samples 11-14 indicate that the filters were highly effective for recovering RNA from the conditioned media samples. The position of the peak near the left-hand side of the X-axis, and the lack of peaks further to the right, shows that all of the RNA detectable by this instrument in RNA retained on the filters was small RNA, of a size range centered around ˜100 bases (as calibrated by comparison of the peak positions to the molecular size marker “ladder” shown in the last panel). Example 6 Use of Biomolecules Recovered from MPs for Biomarker Discovery [0039] It is contemplated that RNA recovered from fractionated MPs obtained from different samples of cell-free bodily fluids will be used as input for determination of the relative levels of multiple different microRNAs in the samples (a process known as “microRNA profiling”). Comparison of microRNA profiles between different types of samples will allow associations to be made between microRNA profiles and phenotypic differences between the samples. For example, microRNA profiles in RNA extracted from size-fractionated MPs obtained from cell-free bodily fluids from healthy individuals, can be compared with microRNA profiles in RNA extracted from size-fractionated MPs obtained from cell-free bodily fluids from individuals known or suspected of having pathological condition(s), and appropriate analyses carried out to identify differences in microRNA profiles that can be correlated with specific pathological condition(s). In a similar manner, it is contemplated that RNA recovered from fractionated MPs obtained from different samples of conditioned media derived from primary or long-term cultures of cells grown in vitro will be used as input for determination of the relative levels of multiple different microRNAs in the samples. Comparison of microRNA profiles between different types of conditioned media samples will allow associations to be made between the microRNA profiles and phenotypic differences of the individuals from whom the cells that were used to generate the conditioned media were obtained. For example, microRNA profiles in RNA extracted from size-fractionated MPs obtained from conditioned media recovered from cells cultured from healthy individuals, can be compared with microRNA profiles in RNA extracted from size-fractionated MPs obtained from conditioned media recovered from cells cultured from individuals known or suspected of having pathological conditions, and appropriate analyses carried out to identify differences in microRNA profiles that can be correlated with specific pathological conditions. [0040] In a similar manner, it is further contemplated that proteins and other types of nucleic acid, including DNA and messenger RNA (mRNA) recovered from fractionated MPs obtained from different samples of cell-free bodily fluids and conditioned media will be used as input for determination of the relative levels of multiple different proteins and other types of nucleic acids. Comparison of levels of proteins and other types of nucleic acids between different types of samples will allow associations to be made between their levels and phenotypic differences between the samples. For example, levels of proteins and/or mRNA extracted from size-fractionated MPs obtained from cell-free bodily fluids from healthy individuals or from conditioned media derived from the cultured cells of healthy individuals, can be compared with levels of proteins and/or mRNA extracted from size-fractionated MPs obtained from cell-free bodily fluids or conditioned media derived from the cultured cells of individuals known or suspected of having a pathological condition, and appropriate analyses carried out to identify differences in microRNA profiles that can be correlated with specific pathological condition(s). In all of the above examples, it is contemplated that observed differences in levels of analytes between samples can be validated for use as biomarkers. [0041] Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may in some cases be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.

Described herein are methods, devices, and compositions for fractionation and processing of microparticles from biological samples, and to methods for obtaining and using the microparticles for biomarker discovery. Biological samples include cell-free fluids, for example blood plasma, blood serum, cerebrospinal fluid, urine, and saliva, as well as conditioned media. Conditioned media is the liquid growth media used to propagate cells in vitro. Purification of microparticles from cell-free fluids is challenging, typically accomplished by prolonged ultracentrifugation. Described herein is an alternative method for efficiently harvesting and processing microparticles from cell-free fluids and from conditioned media. Embodiments described herein relate to use of the microparticles and their contents recovered from conditioned media derived from propagation of human and animal cells, as a source of biomarkers for diagnosis and prognosis of diseases and pathological conditions.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to and is a continuation of U.S. patent application Ser. No. 10/989,285 filed Nov. 17, 2004, said application claiming priority to U.S. Provisional Patent Application Ser. No. 60/520,385 filed Nov. 17, 2003, entitled “Method and System for De-Identification of Patient Microdata,” each of which is assigned to the assignee of this application and is incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention is directed to computer-related and/or assisted systems, methods, and computer program devices for facilitating efficient and effective use of patient and/or individual related information. More particularly, the present invention relates to techniques for facilitating efficient and effective use of patient and/or individual related information such as medical and/or health related information in compliance with Health Insurance Portability and Accountability Act (HIPAA) of 1996. [0004] 2. Description of the Related Art [0005] Some prior attempts have been made in unrelated fields in the healthcare industry to protect patient related information for various reasons. The prior art has not addressed what can be shared or disclosed based on HIPAA regulations. [0006] The Knapp patent, U.S. Pat. No. 6,278,999, incorporated herein by reference, discloses an information management system for personal health digitizers (see FIG. 1 ) wherein a centralized database 100 collects and stores monitoring data from a large number of individuals and processing elements 101 - 108 perform statistical analysis of the collected data on a per consumer, population segment, or query-specific basis. The database is architected in a hierarchical manner to limit users' access to only that prepartitioned segment of the collected data that the particular class of user is authorized to analyze. Data is gathered from remotely located sources T 1 -Tn, comprised of individual consumers using Personal Health Digitizers to take readings on themselves or family members and downloading the data to the information management system IMS via a personal computer modem and Internet browser T 1 -Tn communicating with an interactive website WS and its data router DR. Alternatively, data can be communicated to the information management system IMS via consumer terminal equipment T 1 -Tn and the Pubic Telephone Switched Network PTSN. [0007] Data from Personal Health Digitizers communicated to the information management system IMS can be accessed by those consumers who communicate the data via terminal equipment T 1 -Tn, by health care providers at their terminal equipment and servers S 1 -Sm, by institutions via their terminal equipment and servers I 1 -Ij, by medical practitioners, and others whom the consumer designates. These users, broken down into classes, can access the information management system IMS and its analysis functions only to the extent authorized by the consumer. Access control via the communication network PTSN is enforced by the use of database filters 103 - 106 architected to provide customized access to selected classes of users. The granularity of the data made available to the various classes of users is further selected and limited to prevent the users from deriving information about the consumer population that they are not entitled to receive. Data processing algorithms 108 operate on the raw physiological data collected from individual consumers and produce additional data that aids in identifying potential physiological problems. Interpretive processing systems 107 , either standard software database processes or neuromorphic systems, such as expert systems or neural networks, use pattern recognition operations to analyze the collected data for correlations with regard to cohort-based sets of criteria identified. [0008] The Petculescu patent, U.S. Pat. No. 6,405,207, incorporated herein by reference, discloses a multidimensional, multilevel database system (see FIG. 2 ) wherein query syntax is used to operate a database engine 204 that extracts and aggregates in a report 206 only the data from those items that are specified in the query. A database client 201 provides facilities for multiple users to specify the data to be provided from the database 205 . The query 202 then passes to query processor 203 , where it is converted into sequenced operations performed by an execution engine 204 to obtain the specified data. The execution engine 204 then aggregates data into a report which the database client 201 displays. The query processor 203 , execution engine 204 , and database 205 are typically components residing in one or more central computers accessed by query software operating from individual personal computers that serve as database clients 201 . [0009] The Zubelida patent, U.S. Pat. No. 6,397,224, incorporated herein by reference, discloses a system (see FIG. 3 ) for anonymously linking multiple data records 352 by double-encoding and assigning an anonymization code to data elements that can be used to identify an associated individual. Data records 352 are stored within an input database 354 , either conventional or computerized. Each record includes a plurality of identifying elements 356 including, for example, name birth date, address, ZIP code, telephone number, healthcare identifier, and the like. Identifying elements 356 of the data records 352 are encoded by two or more modules 358 that can be combined or integrated into a single software application or device. The identity reference encoding modules 358 operate in multiple steps. First, identifying elements 356 of a data record are broken into subsets 362 . The identifying elements are then translated into encoded identity references 360 by applying a cryptographic hash function or other hashing scheme, such as symmetric or public key cryptographic algorithms. This process can be repeated one or more times if the system 350 contains one or more additional identity reference encoding modules 358 , with the goal of reducing the probability of an unintended collision where two subsets 362 share the same encoded identity reference 360 . [0010] The system 350 also includes an anonymization code database 368 that stores anonymization code 366 assignments (for example, serial numbers) associated with encoded identity references 360 and in turn a particular individual, group, or population. An anonymization code lookup module 364 utilizes a database query module 370 to retrieve the anonymization code 366 for each of the encoded identity references 360 . If no code is associated with a particular reference, an anonymization code assignment module 372 uses an anonymization code generation module 374 to assign a new, unique anonymization code 366 to each of the encoded identity references 360 that describe an individual, group or population. A database update module 376 is used to ensure that the assigned anonymization code 366 corresponds to the multiple encoded identity references 360 associated with an individual, group, or population. Finally, an anonymization code insertion module 380 inserts the assigned anonymization code 366 into the anonymized data record 382 . The inclusion of an identifying element removal module 378 is optional. [0011] However, to the knowledge of the inventors, no attempts have been made to aggregate information about population, drug usage, health and/or medical related information in a manner that can be legitimately used. In addition, no attempts appear to have been made to aggregate health and/or medical related information in compliance with HIPAA regulations and/or in a manner that can be used to assist healthcare providers, health management companies, in research, healthcare and/or marketing, for example, in a small geographic area. SUMMARY OF THE INVENTION [0012] The present invention is a method and/or computer-implemented system to provide patient medical information in a way that in at least one embodiment, for example, conforms to HIPAA regulations regarding maximum re-identification risk. The invention is based on aggregation methods. The first aggregation method uses geographic proximity among patients, the second uses similarity of medical information. Other aggregation methods may be combined and/or utilize the overall aggregations process developed in the present invention to de-identify geographic, individual or patient-related data and/or conform to HIPAA regulations. [0013] The first aggregation method, while maintaining low overall re-identification risk, also dramatically reduces the range of the risk of re-identification between zip codes. The second aggregation method provides more useful information than HIPAA “safe harbor” regulations, while also resulting in a much lower risk of re-identification. [0014] The aggregation based on geographic proximity in the present invention includes as a first step ensuring that the input data is valid. This process begins by identifying patient records without zip codes. Those patient records without a zip code that cannot be corrected for are removed and/or filtered from the database. Next, the first unmerged zip code and its corresponding population is retrieved. If the population of the zip code is greater than the minimum needed to conform to HIPAA regulations (the safe limit), then the zip code is left alone. If the population is less than the safe limit, the zip code is then combined with nearby zip codes until the geographic area is greater than the safe limit. This is repeated until the aggregation process for all zip codes is finished. [0015] The second method of aggregation, which is based on aggregating across medical information, has an initial process of clustering, followed by coding, and finally a process for providing the de-identified data. The process is implemented on a computer that is connected to a patient profile database, a cluster database, and a database of patient medical information. The clustering part of the de-identification process is intended to place the medical information into a hierarchy that is meaningful to the intended user of the de-identified information. The coding process is the second part of the de-identification method. The process of coding extracts the necessary information from the patient medical information database and the patient profile database to determine the prevalence of a medical characteristic in a zip code. This level of usage by zip code is then stored into the cluster database. The final part of the de-identification method is to receive request for zip codes or medical characteristics and respond with the appropriate de-identified information. [0016] In one embodiment of the invention, a computer-implemented method for de-identifying data collected for patients, includes providing information representative of at least one patient, at least one medical characteristic associated with at least one patient, and a geographic area. This method also includes associating at least one patient with at least one geographic area, and creating at least one aggregated geographic area capable of de-identifying information through aggregating zero or more smaller geographic areas. Finally, the method aggregates information by medical characteristic and associates this information with the aggregated geographic area capable of de-identifying information. [0017] In another embodiment of the invention, a computer-implemented method for de-identifying data collected for patients includes providing information representative of at least one patient, at least one medical characteristic associated with at least one patient, and a geographic area of the at least one patient. This method also provides at least one organizational structure for organizing medical characteristics, then associating the organizational structure with at least one geographical area and at least one medical characteristic. Information is then aggregated by the at least one medical characteristic and the at least one geographic area therein into the organizational structure. [0018] In another embodiment of the invention, a computer-implemented method assesses compliance of de-identified data with data de-identification requirements, which includes safe harbor. The method includes the steps of quantifying a safe harbor risk for at least one data set by applying the safe harbor to the at least one data set, and then also applying at least one method of de-identifying data to the at least one data set. The method next compares the re-identification risk of the at least one de-identifying method to the safe harbor risk to determine whether the re-identification risk is lower than the safe harbor risk. [0019] In another embodiment of the invention, two previous embodiments are combined together. The embodiment of aggregating medical information with an organizational structure is advantageously combined with the embodiment based on aggregating smaller geographic areas. [0020] There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. [0021] In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. [0022] As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. [0023] These together with other objects of the invention, along with the various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0024] FIG. 1 is an illustration of a prior art information management system for personal health digitizers. [0025] FIG. 2 is an illustration of a prior art multidimensional, multilevel database system. [0026] FIG. 3 is an illustration of a prior art system for anonymously linking multiple data records. [0027] FIG. 4 is a block diagram illustrating the overall system layout for aggregation based on medical information. [0028] FIG. 5 is a flow chart illustrating the steps performed in organizing the medical characteristics into a hierarchy. [0029] FIG. 6 is a flow chart illustrating the steps performed in coding the information contained in the patient records. [0030] FIG. 7 is a flow chart illustrating the steps performed in providing the de-identified information in response to a specific request. [0031] FIG. 8 shows a block diagram of a computer used for implementing one or more embodiments of the present invention, in accordance with a computer implemented embodiment. [0032] FIG. 9 illustrates a block diagram of the internal hardware of the computer of FIG. 8 . [0033] FIG. 10 illustrates a block diagram of an alternative computer of a type suitable for carrying out the present invention. [0034] FIG. 11 is a flow chart illustrating the steps performed in aggregating medical information based on zip code [0035] FIG. 12 is a diagram illustrating anomalous birth dates in the patient database. DETAILED DESCRIPTION OF THE INVENTION [0036] The following detailed description includes many specific details. The inclusion of such details is for the purpose of illustration only and should not be understood to limit the invention. Throughout this discussion, similar elements are referred to by similar numbers in the various figures for ease of reference. In addition, features in one embodiment may be combined with features in other embodiments of the invention. [0037] The present invention is a method and/or computer-implemented system to provide patient medical information in a way that in at least one embodiment, for example, conforms to HIPAA regulations regarding maximum re-identification risk. The invention is based on aggregation methods. The first aggregation method uses geographic proximity among patients, the second uses similarity of medical information. Other aggregation methods may be combined and/or utilize the overall aggregations process developed in the present invention to de-identify geographic, individual or patient-related data and/or conform to HIPAA regulations. [0038] The first aggregation method, while maintaining low overall re-identification risk, also dramatically reduces the range of the risk of re-identification between zip codes. The second aggregation method provides more useful information than HIPAA “safe harbor” regulations, while also resulting in a much lower risk of re-identification. [0039] The aggregation based on geographic proximity method in the present invention, includes as a first step, providing de-identified data that is useful for marketing or other purposes, to ensure that the input data is valid. This process begins by identifying patient records without zip codes. Those patient records without a zip code that cannot be corrected for are removed and/or filtered from the database. The remaining records are treated as any other records that originally had zip codes. In an actual test database of patient information, records with out zip codes made up about 38.6% of the total patient records. The removal of any records without a zip code advantageously results in an under estimate of re-identification. It is less likely that a patient could be identified with public records, when that person does not have a zip code, as compared to one who does. [0040] One group of records in the test database with missing zip codes, belonged to zip codes that could not be found in the 2000 Decennial Census. This accounted for 19.2% of zip codes but only 1.9% of patients of the baseline population. This can occur because these are new zip codes created since the last census and because the Census Bureau and the United States Post Office differ in their assignment of zip codes. [0041] More information about how the zip code assignment differs between the United States Post Office and the Census Bureau may be found at http://pe.usps.gov/text/dmm/1606.htm and http://www.galaxymaps.com/wezipchg.htm. The information found at these sites was used to map the 2000 census data into the zip codes used by customers, which are United State Post Office zip codes. This mapping is preferred because not only is it more forward looking and current, but because it also maximizes the estimated risk of re-identification. It disaggregates the Census data into the United State Post Office zip codes rather than aggregating the United State Post Office data into Census zip codes. This disaggregation was also used to correct for patients who lived in new zip codes that had been formed out of previously existing zip codes. [0042] The disaggregation proceeded as follows. [0000] C i =Census population in i th code, and [0000] P ij =Population in j th zip code formerly part of i th zip code, then [0000] C ij =C i *P ij /Σ j P ij (summing over all zip codes formerly part of the i th zip code) [0043] In general, a population was assigned to new zip codes that split the population of the old zip code equally among the new ones created out of it. It was assumed that when a new zip code was formed out of an old one, that the new zip code shared equally in the population. As before, this works to over estimate re-identification risk, since new zip codes areas are growing more quickly than already established zip codes, and therefore, ought to be assigned some proportionately higher degree of the population. [0044] Another group of invalid zip codes, referred to as non-residential areas, are not associated with any geographic area. Instead they represent a specific office building, post office, of post office box. Very few of these zip codes were found in an actual database. [0045] Incorrect zip codes are another source of invalid data. One case of this can be detected when an unrealistically high percentage of the population of are customers. Sometimes this means, an insurance carrier has used its zip code for the zip code of all its patients. A two step search was used to find these incorrect zip codes. The first step was to determine individual zip codes where an insurance company had significantly high over-representation. The second step was to decide if within such a zip code, whether a particular insurance carrier had an unrealistically high share of the total patient records. For the first determination, a straightforward studentization of the insurance company population was used as shown below: [0000] C j =Census population for j th zip code [0000] B j =Insurance company patient population for j th zip code [0000] Exp j =Cj * (Total B Pop)/(Total Census Pop) [0000] Score=( B j −Exp j )/sqrt(Exp j ) [0046] This determination was made, for example, on a purely statistical basis, although additional factors may also be utilized in the first determination. The second determination—identification of possibly aberrant carriers within an overrepresented zip code—was based on the expectation that carriers' shares of the insurance companies patients within a zip code should follow an exponential distribution given a uniform distribution of carriers' population. Since many, if not most, carriers are, however, geographically centered, it is likely that a given carrier might have the bulk of their business within a particular zip code. [0047] Incorrect birthdates were another source of invalid data. These were removed to the extent possible. For instance, the current database has 4 times more centenarians than the 2000 Decennial Census recorded, and also contained a few individuals whose birthdates were in the future. Other dates, such as January 1st of every year, and the first and last day of each month, are also overrepresented. To correct for this, the residuals were calculated from a smooth trace running through all the data. One exemplary representation of the data is plotted, for example, in FIG. 12 . [0048] The first method of aggregation for reducing re-identification risk is based on geographic proximity. The HIPAA “safe harbor” regulations require any geographic indicator to contain at least 20,000 people, and recommend that zip codes be aggregated to the 3 digit level to provide this floor. This level of aggregation has been determined to be generally unnecessary except for a very few zip codes. The present invention advantageously preserves more information than HIPAA “safe harbor” regulations by, for example in one embodiment, making geographic areas more uniform in population size. This is accomplished in one embodiment by merging zip codes only when necessary to achieve a population size whose risk of re-identification would conform to HIPAA “safe harbor” regulations. [0049] The level of risk allowed by HIPAA “safe harbor” regulations was determined by creating a regression model based on the published re-identification risk numbers in the HIPAA legislation. A population of 500,000 can have a re-identification risk of 0.4%, a population of 100,000 can have an identification risk of 3%, and a population of 25,000 can have an identification risk of 10%, these numbers came from a study done by the National Center for Health Statistics. A log linear regression model was created based on these numbers for estimating re-identification risk: [0000] Re-identification probability=10 (−0.66048*sqrt(n/1000)) [0050] From this model it is estimated that the 2000 Decennial Census had an average re-identification risk of 0.85%, with a maximum risk of 8.77% for any one zip code. The estimate for the 1990 Decennial census was an average re-identification risk of 1.01%. The present invention here advantageously results in less risk than the HIPAA legislation models would have resulted in for the 2000 Census data when using the aggregation processes described herein. [0051] This re-identification risk estimate can be made more accurate by accounting for the imperfections in actual data. For example in one embodiment, this imperfection in data due to reasons explained above lower the re-identification risk by about 10%. This is because missing zip anomalies accounted for 9.11% of the data, incorrect zip codes inserted by the insurance accounted for 3.48%, age and birth date anomalies for 1.73%, and age distribution for 3.87%. The overall effect of this is (1−3.48%)*(1−1.73%)*(1+3.87%)/(1+9.11%)=90.30%, or lowering re-identification risk by 10%. [0052] In one embodiment of the present invention, the estimated re-identification risk was 0.16%. This was derived from the baseline patient population containing 448,883 unique 5 digit zip code and birth year combinations. This resulted in a naive re-identification risk of 0.72%. But the population of a particular medical provider is not that same as the entire population. It was 4.62 smaller than the national population, meaning the estimated re-identification risk was 0.72%/4.62=0.16%, since not every patient record will also be unique in the national population. This low rate of re-identification means gender information could also be added.\ [0053] Aggregating to the 3 digit level for zip codes is generally unnecessary to meet the level of risk allowed, except for a very few zip codes. Matching records using zip code and birth year results in a very low risk of re-identification even when using the entire 5 digit zip code. This hypothesis was validated using actual public information along with actual patient information. Software and data was purchased from Pallorium corporation, along with their “People Finder” software for the states of New York and Texas. The data CDs contain a combination of driver's license, voter registration, and property tax records, together with name, address phone number and birth date for each record. This information was compared to the information in the patient database to see how many unique matches occurred, which meant someone could be re-identified. The results are shown in the table below, showing the experimental re-identification risk of 0.01%. At that risk level, gender information can easily be added in compliance with HIPAA “safe harbor” regulations, but birth month, which would increase risk by 12 times, cannot. This means where age, gender, and 5 digit zip code are the only fields in a record matched in a public use data file, de-identification risk can meet HIPAA “safe harbor” regulations. [0000] TABLE Actual Re-Identification Risk for 5-Digit Zip and Birth year New York (%) Texas (%) Patient database 2,844,109 3,524,857 Unique records patient 24,490 0.86% 26,321 0.75% database Public: Found 15,847 0.56% 18,534 0.53% Public: “Unique” 1,096 0.04% 2,038 0.06% Public: True Match 299 0.01% 344 0.01% 2000 Census (estimated risk) 0.84% 0.84% [0054] Turning to FIG. 11 , the process of aggregation based on geographic proximity is described. In FIG. 11 , the process starts by retrieving the first unmerged zip code and its corresponding population 1102 . If the population of the zip code is greater than the minimum needed to conform to HIPAA regulations (the safe limit), then the zip code is left alone 1103 . For example, with one embodiment of the invention, which contained a database with the prescription purchases of over 100 million patients, a zip code with 250,000 people is sufficiently large to conform to HIPAA “safe harbor” regulations. If the population is less than the safe limit 1103 , the zip code is then combined with nearby zip codes containing the same first 4 digits 1104 , until the geographic area is greater than the safe limit 1105 , 1106 . In one embodiment of the invention, this process of combining zip codes was done using a “greedy” algorithm. If the population is still not above the safe limit after merging with all zip code with the same first 4 digit, then it is combined with nearby zip codes with the same first 3 digits 1107 until it is greater than the safe limit 1108 , 1109 . Regardless, if after merging with all other zip codes with the same first 3 digits the population is greater than the safe limit, the aggregation process is finished. This is repeated until the aggregation process for all zip codes is finished 1110 . Other modified version of this process may also be used in the present invention and/or in combination. For example, instead of combining population with the same first 3 digits, other populations may be added to increase the population for the safe limit. [0055] The second method of aggregation, which is based on aggregating across medical information, has an initial process of clustering, followed by coding, and finally a process for providing the de-identified data. The overall design of aggregation based on medical information is shown in FIG. 4 . The process is implemented on a computer 401 that is connected a patient profile database 405 , a cluster database 407 , and a database of patient medical information 413 . The patient profile database stores profile information about patients that is partially independent of their medical information. This includes information like name, address, zip code, etc. The patient medical information database contains their medical information, which could be information such as prescription purchases, current medical conditions, and/or genetic traits. Finally, the cluster database 407 stores the information that is produced during the clustering and coding parts of the aggregation process. [0056] If additional information is needed during any phases of the aggregation process, it can be accessed, for example, at public databases 409 that are connected through the Internet 411 . Information such as census data, population studies, and surveys, can be useful in preparing and filtering patient profile and patient medical information databases. [0057] The clustering part of the de-identification process is intended to place the medical information into a hierarchy that is meaningful to the intended user of the de-identified information. For one embodiment of the invention, the medical information comprised drugs that were placed into a hierarchy based on similarity of drugs. Other types of medical information such as specific medical conditions or genetic traits may optionally be placed into their own hierarchy. For one embodiment of the invention, based on drug usage, prescription purchases of all drugs were placed into a hierarchy that began with the standard 79 second level categories of the uniform formulary therapeutic classification scheme. This is a uniform system of drug classification that many health insurance plans have adopted. These 79 second level categories are then advantageously grouped into one of 30 third level clusters. Those 30 clusters are then grouped into one of 13 fourth level clusters, and finally, those 13 clusters are grouped into one of 4 meta-clusters. In one embodiment of the invention, a single third level cluster optionally contains beta-blockers, direct acting miotics, glaucoma drugs, and sympathomimetics. A single meta-cluster optionally contains sub-clusters like antihistamines, migraine medication, and immunosuppressants. [0058] As illustrated in FIG. 5 , the clustering process begins by associating the medical information with the proper lowest level category 503 . The next step in the process, grouping the lowest level categories into the higher level clusters is done, for example, by determining points of similarity that exist between the separate levels 505 . This determination is made by using an agglomerative clustering algorithm The algorithm is one which places the two closest objects together in one cluster; then the two next closest objects (which can themselves be clusters), and so on, until all objects are in one large cluster. [0059] Once all the second level categories have been associated with higher level clusters 507 , they are then processed 509 and associated with one of the meta-clusters 511 . The grouping into the meta-clusters is more straightforward because of the breadth of the categories. In one embodiment of the invention 4 meta-clusters were used: acute, chronic, dermatological, and miscellaneous, although any number of meta-clusters may be used. After the clusters have been associated with a meta-cluster 513 , all this information regarding the hierarchy structure is stored 515 in the cluster database. The clustering process is then finished 517 . The coding process, shown in FIG. 6 , is the second part of the de-identification method. It combines, in one embodiment, the patient medical information database, the patient profile database, and the cluster database. The process of coding extracts the necessary information from the patient medical information database and the patient profile database to determine the prevalence of a medical characteristic in a zip code. In one embodiment of the invention, involving a prescription database, the information extracted corresponds to whether there is a high/average/low usage for a drug in a zip code. This level of usage by zip code is then stored into the cluster database. The specific combination of high/average/low usage may be determined by the application, user, drug, condition, and the like. [0060] The process of coding 601 retrieves a zip code 603 , it then associates one path of the cluster hierarchy with the zip code 605 . In one embodiment of the invention, an association is performed with one combination of a second level category, a third and fourth level cluster, and a meta-cluster. Additional associations and/or combinations may optionally be used. The process of retrieving zip codes and associating them with the hierarchy is automatic since each zip code is eventually associated with each possible path. The next step is to retrieve a patient profile record from the zip code, and the corresponding record from the patient medical information database 607 . A counter is then incremented that corresponds to the characteristic of the patient's medical information that is of interest 609 . In one embodiment of the invention, the counters for a drug are incremented if a patient bought a prescription for that drug. This is optionally continued until all patient profile records in the zip code have been processed 611 . The usage in the zip code is then compared to the expected usage for the zip code, and the result of high/average/low is stored in the cluster database 615 . This process continues until all zip codes have been processed 613 . The coding process is then finished 617 . Alternative combinations or sequences of the above described coding process may optionally be used. [0061] The final part of the de-identification process is shown in FIG. 7 . This phase retrieves the de-identified data in response to a request to identify an area with a high/average/low level of a medical characteristic 701 . The process begins by receiving a request for a characteristic 703 , then determining what path in the hierarchy that characteristic has been associated with 705 . Next, for the requested medical characteristic, the level of prevalence for all zip codes is retrieved 707 . In one embodiment of the invention, this corresponds to the amount of a drug purchased in that zip code. This retrieval process can be accomplished by retrieving all records for a characteristic, since in the previous clustering process a prevalence level for each zip code of a medical characteristic was stored in the cluster database associated with a hierarchy path. Finally, a response listing is provided 709 , and the process is finished 711 . [0062] Many other types of response listings are also possible after the clustering and coding processes have organized information in the database. For instance, instead of returning a prevalence level by zip code for a medical characteristic, the opposite process could be easily done. The user could make a request for the prevalence level of a medical characteristic for a zip code, and that information could be returned for each level in the cluster hierarchy. In addition, alternative and/or modified steps can be used to filter cluster, and/or aggregate information to appropriately de-identify information in accordance with the present invention. [0063] The present invention is advantageously implemented or, or assisted with on a computer. FIG. 8 is an illustration of a computer 858 used for implementing the computer processing in accordance with a computer-implemented embodiment of the present invention. The procedures described herein may be presented in terms of program procedures executed on, for example, a computer or network of computers. [0064] Viewed externally in FIG. 8 , computer 858 has a central processing unit (CPU) 868 having disk drives 869 , 870 . Disk drives 869 , 870 are merely symbolic of a number of disk drives that might be accommodated by computer 858 . Typically, these might be one or more of the following: a floppy disk drive 869 , a hard disk drive (not shown), and a CD ROM or digital video disk, as indicated by the slot at 870 . The number and type of drives varies, typically with different computer configurations. Disk drives 869 , 870 are, in fact, options, and for space considerations, may be omitted from the computer system used in conjunction with the processes described herein. [0065] Computer 858 also has a display 871 upon which information may be displayed. The display is optional for the computer used in conjunction with the system described herein. A keyboard 872 and/or a pointing device 873 , such as a mouse 873 , may be provided as input devices to interface with central processing unit 868 . To increase input efficiency, keyboard 872 may be supplemented or replaced with a scanner, card reader, or other data input device. The pointing device 873 may be a mouse, touch pad control device, track ball device, or any other type of pointing device. [0066] Alternatively, referring to FIG. 10 , computer 1058 may also include a CD ROM reader 1095 and CD recorder 1096 , which are interconnected by a bus 1097 along with other peripheral devices 1098 supported by the bus structure and protocol. Bus 97 serves as the main information highway interconnecting other components of the computer. It is connected via an interface 1099 to the computer 1058 . [0067] FIG. 9 illustrates a step diagram of the internal hardware of the computer of FIG. 8 . CPU 975 is the central processing unit of the system, performing calculations and logic operations required to execute a program. Read only memory (ROM) 976 and random access memory (RAM) 977 constitute the main memory of the computer. Disk controller 978 interfaces one or more disk drives to the system bus 974 . These disk drives may be floppy disk drives such as 979 , or CD ROM or DVD (digital video/versatile disk) drives, as at 980 , or internal or external hard drives 981 . As previously indicated these various disk drives and disk controllers are optional devices. [0068] A display interface 982 permits information from bus 974 to be displayed on the display 983 . Again, as indicated, the display 983 is an optional accessory for a central or remote computer in the communication network, as are infrared receiver 988 and transmitter 989 . Communication with external devices occurs using communications port 984 . [0069] In addition to the standard components of the computer, the computer may also include an interface 985 , which allows for data input through the keyboard 986 or pointing device, such as a mouse 987 . [0070] The system according to the invention may include a general purpose computer, or a specially programmed special purpose computer. The user may interact with the system via e.g., a personal computer or over PDA, e.g., the Internet, an intranet, etc. Either of these may be implemented as a distributed computer system rather than a single computer. Similarly, the communications link may be a dedicated link, a modem over a POTS line, and/or any other method of communicating between computers and/or users. Moreover, the processing could be controlled by a software program on one or more computer systems or processors, or could even be partially or wholly implemented in hardware. [0071] Further, this invention has been discussed in certain examples as if it is made available to a single user. The invention may be used by numerous users, if preferred. The system used in connection with the invention may rely on the integration of various components including, as appropriate and/or if desired, hardware and software servers, database engines, and/or other content providers. [0072] Although the computer system in FIG. 8 is illustrated as having a single computer, the system according to one or more embodiments of the invention is optionally suitably equipped with a multitude or combination of processors or storage devices. For example, the computer may be replaced by, or combined with, any suitable processing system operative in accordance with the principles of embodiments of the present invention, including sophisticated calculators, hand held, laptop/notebook, mini, mainframe and super computers, as well as processing system network combinations of the same. Further, portions of the system may be provided in any appropriate electronic format, including, for example, provided over a communication line as electronic signals, provided on floppy disk, provided on CD Rom, provided on optical disk memory, etc. [0073] Any presently available or future developed computer software language and/or hardware components can be employed in such embodiments of the present invention. For example, at least some of the functionality mentioned above could be implemented using Visual Basic, C, C++ or any assembly language appropriate in view of the processor being used. It could also be written in an interpretive environment such as Java and transported to multiple destinations to various users. [0074] As another example, the system may be a general purpose computer, or a specially programmed special purpose computer. It may also be implemented to include a distributed computer system rather than as a single computer; some of the distributed system might include embedded systems. Similarly, the processing could be controlled by a software program on one or more computer systems or processors, or could be partially or wholly implemented in hardware. [0075] As another example, the system may be implemented on a web based computer, e.g., via an interface to collect and/or analyze data from many sources. It may be connected over a network, e.g., the Internet, an Intranet, or even on a single computer system. Moreover, portions of the system may be distributed (or not) over one or more computers, and some functions may be distributed to other hardware, and still remain within the scope of this invention. The user may interact with the system via e.g., a personal computer or over PDA, e.g., the Internet, an intranet, etc. Either of these may be implemented as a distributed computer system rather than a single computer. Similarly, a communications link may be a dedicated link, a modem over a POTS line, and/or any other method of communicating between computers and/or users. Moreover, the processing could be controlled by a software program on one or more computer systems or processors, or could even be partially or wholly implemented in hardware. [0076] User interfaces may be developed in connection with an HTML display format. It is possible to utilize alternative technology for displaying information, obtaining user instructions and for providing user interfaces. [0077] The system used in connection with the invention may rely on the integration of various components including, as appropriate and/or if desired, hardware and software servers, database engines, and/or other process control components. The configuration may be, alternatively, network-based and may, if desired, use the Internet as an interface with the user. [0078] The system according to one or more embodiments of the invention may store collected information in a database. An appropriate database may be on a standard server, for example, a small Sun™ Sparc™ or other remote location. The information may, for example, optionally be stored on a platform that may, for example, be UNIX-based. The various databases may be in, for example, a UNIX format, but other standard data formats may be used. The database optionally is distributed and/or networked. [0079] Although the system is illustrated as having a single computer, the system according to one or more embodiments of the invention is optionally suitably equipped with a multitude or combination of processors or storage devices. For example, the computer may be replaced by, or combined with, any suitable processing system operative in accordance with the principles of embodiments of the present invention, including sophisticated calculators, hand held, laptop/notebook, mini, mainframe and super computers, one or more embedded processors, as well as processing system network combinations of the same. Further, portions of the system may be provided in any appropriate electronic format, including, for example, provided over a communication line as electronic signals, provided on floppy disk, provided on CD ROM, provided on optical disk memory, etc. [0080] The invention may include a process and/or steps. Where steps are indicated, they may be performed in any order, unless expressly and necessarily limited to a particular order. Steps that are not so limited may be performed in any order. [0081] To confirm the advantages of the present invention, experiments were carried oui on actual data. The first aggregation method, which was based on geographic proximity, was applied to an actual patient database. This aggregation scheme resulted in about the same number of zip areas ( 889 ) as under the HIPAA “safe harbor” rules ( 875 ), which recommends 3 digit zip codes. More importantly, while not significantly affecting the overall risk, it resulted in a dramatic reduction in maximum risk as the table below shows. [0000] % Unique records when applied to actual patient database Average Risk Minimum Risk Maximum Risk HIPAA “Safe Harbor” .78% .00% 9.61% aggregation Zip code aggregation .77% .36% 1.14% [0082] The second aggregation method, which was based on aggregation across medical information, was run on approximately 700 million actual prescription drug claims made during the 2000-2001 year. This aggregation scheme, applied to the 4 level hierarchy, ideally produces 81 different types of zip codes. There are 3 different levels for each of the four meta-clusters, which results in 3×3×3×3=81 types. At this level of aggregation, the method results in only 148 unique age type pairs, or 0.00024% of the population. This means when age, gender, and zip code are the only fields in a record matched to a public use data file, aggregation based on drug usage can conform to HIPAA “safe harbor—when providing birth •year, birth month; and gender. Further, ages over 90 do not need to be re-coded or aggregated in the de-identified microdata file. This demonstrates that aggregation based on drug usage can preserve useful information, while dramatically reducing re-identification risk in accordance with the embodiments of the present invention. [0083] The many features and advantages of the embodiments of the present invention are apparent from the detail specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention that fall within the true spirit and scope of the invention. Further, since numerous modifications and variations were readily occurred to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents maybe resorted to, falling within the scope of the invention.

A computer-implemented method de-identifies data collected for patients. In at least one embodiment, the method comprises the sequential, non-sequential and/or sequence independent steps of providing information representative of at least one patient, at least one medical characteristic associated with at least one patient thereto, and a geographic area of the at least one patient, and providing at least one organizational structure for organizing medical characteristics. The method also includes associating the at least one organizational structure with at least one geographical area and at least one medical characteristic, and aggregating, in the at least one organizational structure, said information by medical characteristic and the at least one geographic area therein. Various alternative embodiments are additionally disclosed.

This application claims the benefit of U.S. provisional patent application No. 60/410,782, filed Sep. 13, 2002. BACKGROUND OF THE INVENTION This invention relates to a machine for generating energy from a wind source. More particularly, this invention relates to a machine having a rotor that is caused to rotate around a vertical axis by a wind source. The rotor may be coupled to a dynamo-electric generator in order to produce electric power for downstream consumption. Currently, machines for generating energy from wind sources can include large wind turbines mounted at wind sites, along with various deflectors placed upstream of the turbine. Such arrangements can be difficult to install at the wind sites, as the placement of the various deflectors can be complex. In addition, such an arrangement can be unaesthetic and can lessen the beauty of the landscape at the wind site. Accordingly, it would be desirable to provide a machine for generating energy from a wind source having a casing structure within which a rotor having a vertical axis of rotation is positioned. SUMMARY OF THE INVENTION In accordance with the present invention, a machine for generating energy from a wind source is provided having a casing structure within which a rotor having a vertical axis of rotation is positioned. The solutions of the present invention simplify the construction process of the machinery and its installation at a wind site. Furthermore, the machinery may be adjusted to optimize the power extraction from a wind source, and achieves a minimal ecological impact when installed at the wind site. The machinery is applicable for a wide range of power rating consumptions (e.g., from ratings of domestic applications to ratings of primary wind power stations). In some embodiments of the present invention, the machine for generating usable energy from a wind source has a casing structure. A rotor having a blade structure is positioned within the casing structure and has a substantially vertical axis of rotation. The casing structure may define an air inlet upstream of the rotor that is oriented with respect to a prevailing wind direction and an air outlet downstream of the rotor. The casing structure may have a main passage through which air flows and interacts with the blade structure. The casing structure may have first and second side passages that are delimited by first and second sidewalls of the casing structure, respectively. The first and second side passages may converge toward one another near the air outlet forming a zone of low pressure downstream of the rotor. Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial perspective view of the energy generating machine of the present invention, with certain parts removed to show other parts that would otherwise be hidden. FIG. 2 is a view as seen from direction 2 — 2 of FIG. 1 . FIG. 3 is an enlargement of portion 3 of FIG. 2 . FIG. 4 is a sectional view as seen from direction 4 — 4 of FIG. 2 , and which also shows the parts which have been removed in FIG. 1 . DETAILED DESCRIPTION OF THE INVENTION As shown in FIGS. 1-3 , rotor 10 is located in passage 12 for rotation around vertical axis 14 in direction 15 when driven by a wind source (e.g., a natural wind source). Vertical axis 14 is substantially perpendicular to upper cover plate 16 and lower cover plate 18 of general casing structure 20 . Upper cover plate 16 and lower cover plate 18 may be substantially horizontal, and therefore parallel to a ground plane that supports general casing structure 20 . (In FIG. 1 , upper cover plate 16 is not shown in order to show other parts of the machine that would otherwise be hidden.) Rotor 10 may include a blade structure. In the example shown in the FIGS., the blade structure of rotor 10 includes a plurality of blades 22 that are cantilevered from rotation shaft 24 . Blades 22 may be panels having a concave configuration, as shown in the FIGS. Blades 22 may have other configurations, such as a spiral shape, to increase the power extraction from the wind source. Passage 12 may be delimited laterally by opposite side walls 26 and 28 and vertically by upper and lower cover plates 16 and 18 , respectively. Side walls 26 and 28 extend from inlet opening 30 of passage 12 to outlet opening 32 of passage 12 . Side walls 26 and 28 may be substantially parallel to each other in portion 34 of passage 12 , while sidewalls 26 and 28 may converge towards each other in portion 36 of passage 12 . Inlet opening 30 faces a prevailing wind direction in order to collect and achieve air flow F in portion 34 of passage 12 . In portion 34 , the path of air flow F is initially parallel to sidewalls 26 and 28 . Air flow deflector members, consisting of upstanding panels 38 - 43 , are spaced apart at predetermined positions in portion 34 in order to partially surround rotor 10 along a circular sector 46 . Portions F i of air flow F are deflected by panels 38 - 43 , thereby causing the air particles of flow F to fill compartments 48 of the rotor. Compartments 48 are delimited by blades 22 and upper and lower cover plates 16 and 18 , respectively. The configurations of panels 38 - 43 (shown as both concave and straight in the FIGS.), and their orientation, cause the air particles to impinge on the surfaces of blades 22 at predetermined angles. The predetermined angles influence the resultant driving force achieved on rotor 10 by the wind source. The air particles that enter compartments 48 rotate with rotor 10 and run along blades 22 until they are discharged through passage 50 . Thus, the air particles lose their quantity of motion or energy in order to drive rotor 10 . Narrow passages 52 and 54 , which are respectively delimited by sidewalls 26 and 28 , are on opposite sides of the circular sector 46 occupied by panels 38 - 43 . Upper and lower cover plates 16 and 18 , respectively, vertically delimit passages 52 and 54 . Upstanding casing structures 56 and 58 are located in another circular sector 60 surrounding rotor 10 . Face 62 of casing structure 56 , together with panel 38 , form passage 64 . Similarly, face 66 of casing structure 58 , together with panel 43 , form passage 68 . Face 70 of casing structure 56 surrounds a portion of rotor 10 . Similarly, face 72 of casing structure 58 surrounds another portion of rotor 10 . Passage 50 is formed between face 74 and face 76 . Face 78 and sidewall 26 complete narrow passage 52 . Similarly, face 80 and sidewall 28 complete narrow passage 54 . Preferably, passage 50 is centered on axis 82 , and narrow passages 52 and 54 are spaced symmetrically apart with respect to axis 82 , as shown in the FIGS. By means of the described arrangement, portions of air flow F that have not entered rotor 10 (see portions of air flow F referenced as F 1 and F 2 ) will run through narrow passages 52 and 54 to create a low pressure region in portion 36 . The low pressure region in portion 36 induces the extraction of air particles from rotor 10 through passage 50 . The extraction occurs when a compartment 48 of rotor 10 is facing passage 50 . The sectional size of passage 50 influences the average speed of the air particles when moving with rotor 10 . More particularly, a restricted sectional size of passage 50 , compared to the total sectional size of passages formed by panels 38 - 43 on sector 46 , increases the average speed of the air particles rotating with rotor 10 . The increase in the average speed of the air particles extracts more rotation power for rotor 10 , which consequently increases the electric power that can be obtained for downstream consumption. The low pressure region 36 extends beyond outlet opening 32 so that the air particles of flow F are ultimately discharged from passage 32 . Rotor 10 is supported for rotation in direction 15 by supporting shaft 24 in bearings 84 and 86 , seated in upper cover plate 16 and lower cover plate 18 , respectively (see FIG. 4 ). Dynamo-electric generator 88 may be coupled to shaft 24 , as shown in FIG. 4 . External plates 90 and 92 , which have a cylindrical shape, surround side walls 26 and 28 . As a result, general casing structure 20 has a homogenous cylindrical appearance to the external observer. In addition, the resulting cylindrical form of general casing structure 20 presents low disruption to air flow investing the entirety of general casing structure 20 . Lower case plate 18 may be provided with wheels 94 , which may be supported and guided by ground rail 96 . Ground rail 96 may be circular in order to rotate lower case plate 18 around a vertical axis of the machinery. Circular rack 98 , which lines lower cover plate 18 and is concentric to the vertical axis of the machinery, may be engaged by pinion 100 of motor 102 . By rotation of motor 102 , general casing structure 20 may be rotated around the vertical axis of the machinery to orient inlet opening 30 with respect to a prevailing wind direction, thereby maximizing power extraction from the wind source. The prevailing wind direction may be sensed by a wind direction sensor that supplies information signals which may be used by a control and regulation unit to drive motor 102 , resulting in calculated rotations that orient inlet opening 30 with respect to the prevailing wind direction. The external cylindrical form of general casing structure 20 offers low air obstruction when rotating general casing structure 20 around the vertical axis of the machinery to orient inlet opening 30 with respect to the prevailing wind direction. Limiting the power extraction from the wind source in situations of high wind speeds may be achieved by rotating baffles 104 towards each other to form a diverging passage for the air flow reaching and passing through rotor 10 . A rotated position of baffles 104 is shown by the dashed lines in FIG. 2 . The inclusion of rotor 10 within general casing structure 20 greatly reduces the noise level that rotor 10 produces during rotation caused by the wind source. Furthermore, protection grids (not shown) may be installed across inlet opening 30 and outlet opening 32 to prevent humans and animals from entering passage 12 . The protection grids would be visible and would present low air obstructions to the air flow F needed in passage 12 . Higher power ratings of the machinery may be achieved by increasing the overall sizes of rotor 10 and passage 12 . The major increases in size can be in the diameter of rotor 10 and in the plan dimensions of passage 12 . These alterations would result in a lower height of general casing structure 20 with respect to the height of traditional wind driven machinery having the same power rating. An increase of the power ratings can also be achieved by mounting multiple units, such as the unit shown in FIG. 4 , one above the other in order to form a vertical column of small plan occupancy. The machine of the present invention may be installed in various locations where it is desired to produce electric power from a wind source. For example, the machine of the present invention may be installed on a roof of a tall building in an urban setting, thereby taking advantage of the high winds present at such a height and making efficient use of available space. Thus, a wind powered energy generating machine is provided. One skilled in the art will realize that the present invention can be practiced by other than the described embodiments, which are presented for purposes of illustration and not of limitation, and that the present invention is limited only by the claims which follow.

A machine for generating usable energy from a wind source is provided. The machine includes a casing structure that may define an air inlet oriented with respect to a prevailing wind direction and an air outlet. The casing structure may be substantially cylindrical. A rotor having a blade structure is positioned within the casing structure and has a substantially vertical axis of rotation. The casing structure may include two side passages for creating a zone of low pressure downstream of the rotor near the air outlet.

SUMMARY OF THE INVENTION The basic purpose of the invention is to provide a training device for interactively guiding a tennis racquet by means of exercising a towing force on a cord, which is connected with the tennis racquet, in the sequence corresponding to some certain points and phases of the swing during the execution of the strokes. In particular, for the serve, fore-, and backhand smash, fore-, and backhand slice, and volley strokes. This is achieved according to the invention with a training device, which includes a vertically adjustable support that is telescopically connected with a vertical guide pole that is fixed on the wall. On the upper part of the support is arranged a frame for supporting a shaft of a swivel-arm that is constructed such that the swivel-arm is slanted upward. On the proximal end of the swivel-arm, a weight-balance is fixed that turns the swivel-arm into the upper position in which the swivel-arm is automatically arrested by means of an arresting mechanism fixed on the frame. On the distal end of the swivel-arm is fixed a ring, which includes a suspension arrangement to hang a ball. On the support and the swivel-arm are arranged some pulleys and devices to exercise the towing force on the cord, which is connected with the tennis racquet through a stirrup. The mechanisms for exercising the towing force on the cord are adjustable to define the parameters such as direction, quantity, and timing of the towing force according to the kind of stroke, the body height of the player and the player's skill level. The motto of the present training device is “Practice slowly, learn quicker”. That means: the player is not under pressure to respond quickly and can thereby feel and sense the whole movement involved. The ball being placed in the ideal hitting zone gives even a beginner the possibility of hitting the ball in the very first practice. The player is able to watch in slow motion the way in which the racquet face comes to the ball. In particular, it is very important to watch the difference between the flat-, slice- and topspin serve swing at the meeting point. The prescribed position of the hanging ball is defined by means of a stepping plate with marked footprints placed at certain distances from the hanging ball or from the ring. During serve training, the ring allows the player to visualize the ideal tossing zone, and both the direction and the height of the toss for the different kinds of serves, i.e., flat-, slice-, and topspin serves. During training of the fore- and backhand slice and volley, the marked footprints give the player the possibility of training or learning the footwork in the sequence corresponding to the swing. The cord, by being connected with the tennis racquet distinguishes the present training device, in particular by the interactive guiding of the tennis racquet during the swing. The other portion of the cord runs through some pulleys and a moveable releasing device to an anchor point on the support. The towing force on the cord is exercised by means of an elastic rope that is fixed in the moveable releasing device. In addition, a trigger is mounted on the support to fix and release a bead that is pressed on the cord at a certain distance from the anchor point. At the waiting stance for serve training, the bead is fixed in the trigger and the portion of the cord between the anchor point and the bead is strained by means of the elastic rope, the proximal end of the swivel-arm is free from the arresting mechanism to let it turn and thereby let a player pull the racquet down. From the waiting stance to the end of the back swing (the upper, at-rest position of the swivel-arm), the weight-balance on the proximal end of the swivel arm exercises a relatively weak force on the cord to let same guide the tennis racquet in the correct way to the end of the back swing at which the proximal end of the swivel-arm is arrested. Thus, the tennis player is forced to go through the prescribed position on the end of the back swing because the defined length of the cord does not allow dropping the right elbow lower than shoulder height and tilting the racquet shaft to the wall. At the end of the back swing, there is no hindrance from the cord so as to allow the player to execute the next phase of the swing (i.e. a loop) in the correct direction back, downward. The construction of the stirrup does not allow the racquet and arm to go in the wrong direction, but rather allows the arm to drop the head of the racquet in the correct way, that is, to the small of the back. At the lowest point of the loop, after a short plucking of the cord which releases the trigger, the towing force will be activated overall on the cord and a player will be interactively led to the next prescribed position of the swing, which includes the full stretching of the arm and body. At the full stretching of the arm and body (the point is adjustable), the moveable releasing device enters into a releasing port that is adjustably mounted on the lower part of the support, and through this interaction the cord will be set free from the releasing device so as to allow the player to hit the hanging ball and follow-through without hindrance from the cord. All points and phases of the swing are adjustable by means of shifting both the trigger and the releasing port. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be discussed in detail hereinafter in connection with the drawings, whereby the individual aspects and advantages of the invention, whether or not they have been discussed above, can be recognized more clearly. All figures of the drawings relate to the same preferred exemplary embodiment of the training device of the invention, whereby: FIG. 1 is a side view of the device for serve training, FIG. 2 is a top view of FIG. 1, FIG. 3 shows the tennis player in position with a racquet at the lowest point of the loop of the serve swing, FIG. 4 is an opposite side view of the device for slice, volley, and smash training, FIG. 5 is a top view of FIG. 4 of the stepping plate for slice, volley and smash training, FIG. 6 is a side view of FIG. 7, FIG. 7 is a front view of the grip of the tennis racquet with the stirrup, FIG. 8 is an enlarged fragmentary view of a top part of the holder shown in FIG. 1, FIG. 9 is a cross-sectional view along the line IX—IX of FIG. 8, FIG. 10 is an enlarged, fragmentary view of a lower part of the holder shown in FIG. 1, FIG. 11 is a cross-sectional view along the line XI—XI of FIG. 10, FIG. 12 is a longitudinal cross-sectional view along the line XII—XII of FIG. 13, FIG. 13 is an enlarged, fragmentary front view of the lower part of the holder shown in FIG. 1, FIG. 14 is an enlarged, fragmentary view of the top part of the holder shown in FIG. 4, FIG. 15 is an enlarged, fragmentary front view of the releasing port shown in FIG. 14, and FIG. 16 is a side view of FIG. 15 . DETAILED DESCRIPTION According to the basic design illustrated in FIGS. 1, 2 , 4 and 5 , the training device illustrated in the drawings includes a vertically adjustable support 1 , which is telescopically connected with a vertical guide pole 2 that is fixed by means of two pylons 3 on a wall 4 . The support 1 can be moved along the guide pole 2 and fixed by hand at the desired height by means of a fixture 5 . Smooth sliding of the support 1 is provided by means of two plastic cuffs 6 which are firmly fixed on both ends of a telescopic tube 7 of the support 1 (see FIGS. 1 and 10 ). On the upper part of the telescopic tube 7 is arranged a three-cornered frame 8 that is constructed such that the upper side of the triangle is slanted upward. The free end of the frame 8 has a support 9 for a shaft 10 of a vertically swiveling arm 11 which has on a proximal end an adjustable fixed balance-weight 12 that turns the swivel-arm 11 into the upper at-rest position 11 that is defined by a catch 13 arranged on the frame 8 . The swivel-arm 11 can be set free by pulling a releasing cord 14 to disengage the catch 13 (see FIGS. 1, 8 and 9 ) On a distal end of the swivel-arm 11 , a ring 15 is fixed asymmetrically relative to the long axis of the swivel-arm to train the user with respect to tossing the ball during serve training. The ring 15 includes a suspension 16 for hanging a ball 17 in the desired hitting zone, which comprises two pieces of Velcro™ fastening 18 being hung on two threads 19 in such a way as to enable the ball to fly by hitting it with a tennis racquet 20 (see FIGS. 1 and 2 ). According to FIG. 2, the position of the tennis player P relative to the ring 15 and correspondingly to the ball 17 and to a pulley 25 is defined by means of a pair of footprints 21 on a stepping plate M, which is placed on the ground 43 . On the stepping plate M are marked three pairs of footprints 21 , 21 a , 21 b with the base line markings 22 , 22 a , 22 b at different distances relative to a point F, which is the vertical projection of the ring center (see FIG. 1 ), to define the position of the player P depending upon the different kinds of serve (flat, slice, topspin serve). According to FIGS. 1, 6 and 7 a stirrup 23 is fixed on the tennis racquet 20 , which is connected with a cord 24 that runs upwards to the pulley 25 fixed on the distal end of the swivel-arm 11 , through the pulley 25 , to a further pulley 26 fixed on the top of the telescopic tube 7 , and then downwards through a trigger mechanism 33 to a moveable releasing device 27 , which has a releasing pulley 28 . After turning around the pulley 28 , the cord 24 runs upwards along the tube 7 to an anchor point 29 . On the tube 7 , between the frame 8 and the fixture 5 , vertically adjustable clamp 32 is arranged, which includes the trigger mechanism 33 fixed on a plate 34 . The trigger 35 turns on a stub axle 36 through a torsion spring 37 from a level position 35 f into a vertical position 35 v , which are defined or limited by a stop 38 (see FIGS. 1, 8 , 10 , 13 ). In FIG. 8, the trigger 35 is shown in the working, level position 35 f being stopped on the stop 38 under the pressure of a bead 39 , which bead 39 is steadily clamped on the cord 24 at a certain distance from the anchor point 29 . The pressure on the bead 39 is exercised through the cord 24 by means of an elastic rope 30 one end of which is fixed on the moveable releasing device 27 , then the elastic rope 30 runs through three pulleys 31 fixed on the lower and middle parts of the tube 7 to another moveable releasing device 70 (see FIGS. 1, 4 , 8 , 10 , 13 ). The elastic rope 30 , being prestretched in the trigger position 35 f , exercises the towing force through the releasing device 27 only on the part of the cord between the bead 39 and the anchor point 29 . The working level position of the trigger 35 f corresponds to the execution of the serve swing from a waiting stance of the player P A (shown on FIG. 1 as the racquet 20 A with a hand), through a position of the player P B (see FIG. 1) up to a lowest point of the loop of the serve swing, and through a position of the player P C (see FIG. 3 ). Only at the lowest point of the loop, i.e. the position of the player P C (FIG. 3 ), the towing force will be activated overall on the cord 24 , correspondingly on the racquet 20 , by means of the plucking the cord 24 and moving the bead 39 shortly upwards to let the trigger 35 turn or move via the torsion spring 37 into the vertical position 35 v and move the bead 39 out of contact with a fork-like cutting 40 of the trigger 35 (see FIG. 13 ). On FIG. 8 in large scale, the upper part of the support 1 is shown with the frame 8 , on which the catch 13 is arranged to fix the swivel-arm 11 in the upper attest position. A pin 41 fixed on the proximal end of the swivel-arm 11 will be automatically arrested with the catch 13 , this turns with a torsion spring 42 on an axle 45 . In the waiting stance, the catch 13 is stopped by means of a stop 44 (see FIG. 9 ). The moveable releasing device 28 includes a carrying member 46 to fix the elastic rope 30 between two clamping screws 47 , an offset hinged folding-bracket 48 and a releasing mechanism 49 . As shown on FIG. 13, the folding-bracket 48 is offset hinged relative to the cord 24 , on a joint-pin 50 in the carrying member 46 in order to provide the moment arm for secure folding out after releasing the stub axle 51 , bearing the turn-pulley 28 , out of the contact with two rotary latches 52 of the releasing mechanism 49 . The rotary latches 52 with flange cheeks 53 turn on an axle 54 with a torsion spring 55 partly overlapping a hold 56 in the carrying member 46 and being in a groove 57 of the stub axle 51 in the closed position, which is defined by means of a stop 56 and a cutting 57 in the latches 52 (see FIGS. 12 and 15 ). The releasing port 58 is fixed on a vertically adjustable clamp 60 , which is placed on the down part of the tube 7 (see FIGS. 10, 11 and 13 ). By entering into a releasing port 58 , the rotary latches 52 with flanged cheeks 53 will be turned through the contact with flanged cheeks 59 of the releasing port 58 letting the folding-bracket 48 fold out and thereby set the cord 24 free. After releasing the cord 24 , the releasing device 27 is stopped on a rubber shock absorber 61 , which is fixed on the releasing port 58 (see FIGS. 12, 13 and 15 ). FIGS. 6 and 7 show the connection of the cord 24 with the tennis racquet 20 by means of the stirrup 23 , which is fixed on two flanges 62 , 63 bridging the grip of the tennis racquet 20 . The stirrup 23 includes a round rod 64 , an adjustable member 65 , protecting rubber rings 66 , and a glide ring 67 to connect the cord 24 . The flanges 62 , 63 are clamped on the grip by means of two demountable yokes 68 . The form of the rod 64 , the adjustable member 65 and the glide ring 67 provide the shifting of the point of connection accordingly the point of the exerting of the towing force on the tennis racquet 20 , which is a necessary condition during the swing. Although a particular preferred embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.

A training device which interactively guides a tennis racquet by exerting a towing force on a card which is connected to the tennis racquet. The device includes a vertically adjustable support connected with a guide pole fixed to a wall. A swivel arm is movably supported on the support and has a distal end which suspends a ball therefrom. The cord extends along the swivel arm and the support, and one end thereof is connected to the racquet through a stirrup.

CROSS REFERENCE TO RELATED APPLICATION This application is a national phase application based on PCT/EP2003/010812, filed Sep. 30, 2003, the content of which is incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable with a coating layer made from a waste material. More particularly, the present invention relates to a cable including at least one core comprising at least one transmissive element and at least one coating layer, said coating layer being made from a coating material comprising at least one polyethylene obtained from a waste material. Moreover, the present invention relates to a process for producing said cable. For the purposes of the present description and of the subsequent claims, the term “core” of a cable is used to indicate a semi-finished structure comprising a transmissive element, such as an electrical energy transmissive element, an optical signal transmissive element or an element which both transmits both electrical energy and optical signals, and at least one electrical isolation or, respectively, at least one containment element (such as, for example, a tube, a sheath, a microsheath or a grooved core), or at least two elements, one of which is an electrical isolation element and one is a containment element, arranged at a radially outer position with respect to the corresponding transmissive element. For the purposes of the present description and of the subsequent claims, the term “electrical energy transmissive element” is used to indicate any element capable of transmitting electrical energy such as, for example, a metallic conductor element. As an illustrative example, if we consider a cable for transporting or distributing medium/high voltage electrical energy (where medium voltage indicates a voltage comprised between about 1 kV and about 30 kV, whereas high voltage indicates a voltage greater than about 30 kV), the “core” of the cable further comprises an inner semiconductive coating layer arranged at a radially outer position with respect to the conductor element, an outer semiconductive coating layer arranged at a radially outer position with respect to the electrical isolation element, a metallic screen arranged at a radially outer position with respect to said outer semiconductive coating layer, and an external layer arranged at a radially outer position with respect to said metallic screen. For the purposes of the present description and of the subsequent claims, the term “optical signal transmissive element” is used to indicate any transmission element comprising at least one optical fibre. Therefore, such a term identifies both a single optical fibre and a plurality of optical fibres, optionally grouped together to form a bundle of optical fibres or arranged parallel to each other and coated with a common coating to form a ribbon of optical fibres. As an illustrative example, if we consider an optical cable the “core” of the cable further comprises a coating layer arranged at a radially outer position with respect of the grooved core, a tensile reinforcing layer at a radially outer position with respect to said outer coating layer, and an external layer arranged at a radially outer position with respect to said tensile reinforcing layer. For the purposes of the present description and of the subsequent claims, the term “mixed electro-optical transmissive element” is used to indicate any element capable of transmitting both electrical energy and optical signals in accordance with the abovementioned definitions. For the purposes of the present description and of the subsequent claims, the term “coating layer” means any coating deposited on the transmissive element of a cable for protective purposes, e.g. to preventing the damages of the transmission element due to mechanical stresses during manufacturing, installation and use. The present inventions also refers to cables provided with a plurality of cores as defined above, known in the field with the terms “bipolar cable”, “tripolar cable” and “multipolar cable”, depending on the number of cores incorporated therein (in the mentioned cases in number of two, three, or greater, respectively). In accordance with the abovementioned definitions, the present invention refers to cables provided with one or more cores of any type. In other words, the present invention refers to unipolar or multipolar cables, of electrical type for transporting or distributing electrical energy, or of the optical type comprising at least one optical fibre, or of the mixed energy/telecommunications type. 2. Description of the Related Art Nowaday, the possibility of using polymer obtained from waste materials for the manufacturing of new products, is a problem of increasing importance for ecological reason and for reducing costs. In the field of cables, some efforts have been already done in order to use recycled polymer materials, in particular polyvinyl chloride or ethylene polymers obtained from waste cable sheaths. Said recycled polymer materials are generally used for making cable coating layers. For example, JP 2002/080671 discloses a polyvinyl chloride-based recycled plastic composition obtained by mixing and melting covering plastics and sheaths of waste cables containing: (A) polyvinyl chloride and (B) polyethylene or silane-crosslinked polyethylene, with chlorinated polyethylene. The abovementioned polyvinyl chloride-based resin is said to be useful for making cable sheaths. JP 2001/098124 relates to a thermoplastic resin composition and to an electrical cable covered with said composition. The thermoplastic resin composition comprises: (A) 1-99 parts by weight of a resin composition containing a polyvinyl chloride resin and a polyethylene resin, said polyvinyl chloride resin and polyethylene resin obtained from waste electrical cables; and (B) 1-99 parts by weight of a multiphase graft copolymer containing (i) 5%-99% by weight of thermoplastic elastomeric units and (ii) 1%-95% by weight of vinyl polymer units where one of the units form a dispersed phase with a particle size of between 0.001 μm-10 μm in the other units. The abovementioned resin composition is said to have a good flexibility and processability when used as an insulating layer or sheath for a cable. JP 2002/363364 relates to a recycled polyvinyl chloride resin composition comprising a plasticizer having a molecular weight of at least 500 such as, for example, a trimellitate-based, a polyester-based or an epoxy-based plasticizer. The abovementioned composition is said to be useful as covering materials for electrical cables. JP 2002/363363 relates to a recycled polyvinyl chloride-containing resin composition and to an electrical wire or cable made therefrom. Said composition comprises 100 parts by weight of a 99:1 to 70:30 mixture of a polyvinyl chloride resin which typically is a recycled material and a polyolefin resin, and 1-20 parts by weight with respect to 100 parts by weight of said mixture, of a block copolymer of an acrylic polymer and a hydrogenated polybutadiene in a ratio of 50:50 to 10:90. The abovementioned composition is said to be useful as a covering material for wires and cables. JP 2002/103329 relates to a method for recycling used vinyl films (e.g. polyvinyl chloride films) for agriculture. The method comprises cutting the used vinyl films roughly; removing impurities such as metals and sand from cut pieces; feeding dried fluff obtained by grinding, washing, dehydrating, and drying said pieces, a plasticizer, a heat stabilizer, and other additives to a heater mixer; keading them; feeding the mixture in a semi-molten state to a cooler mixer; stirring it feeding it to an extruder; extruding it under heated conditions; passing trough a water bath; and pelletizing it. The obtained pellets are dried to form a compound for molding the electrical cable sheath material. Said electrical cable is said to have good properties comparable to a cable having a virgin polyvinyl chloride sheath. However, the use of recycled polymers may show some drawbacks. In particular, the Applicant has noticed that the use of recycled polyethylene may provide coating layers having poor mechanical properties, in particular stress at break and elongation at break, and poor environmental stress cracking resistance, with respect to those obtained from virgin polymer materials. Moreover, said coating layers may show poor appearance, mainly due to the formation of defects on their surface such as, for example, little agglomerates, which impair not only their appearance and smoothness but also their mechanical properties. The Applicant believes that the above drawbacks may be due to partial degradation of polyethylene upon prolonged exposure to sunlight and to atmospherical agents, and/or to reprocessing to which said polyethylene is subjected, such degradation causing worsening of mechanical properties and processability. SUMMARY OF THE INVENTION Applicant has found that a polyethylene obtained from waste material, in particular a polyethylene obtained from used agricultural films, may be advantageously used for the manufacturing of a coating layer of a cable. In particular, the Applicant has found that the addition of at least one polyethylene having a density higher than 0.940 g/cm 3 to said recycled polyethylene, allows to obtain a coating material able to overcome the above mentioned drawbacks. As a matter of fact, said coating material may be advantageously used in the manufacturing of a coating layer of a cable, said coating layer showing mechanical properties (in particular, stress at break and elongation at break) comparable to those obtained from a virgin polyethylene. Moreover, said coating layer shows a good hot pressure resistance. Furthermore, said coating layer shows an improved environmental stress cracking resistance with respect to the coating layer obtained from a recycled polyethylene alone. In a first aspect, the present invention thus relates to a cable including at least one core comprising at least one transmissive element and at least one coating layer made from a coating material, wherein the coating material comprises: at least a first polyethylene having a density not higher than 0.940 g/cm 3 , preferably not lower than 0.910 g/cm 3 , more preferably of between 0.915 g/cm 3 and 0.938 g/cm 3 , and a Melt Flow Index (MFI), measured at 190° C. with a load of 2.16 Kg according to ASTM D1238-00 standard, of between 0.05 g/10 min, and 2 g/10 min, preferably of between 0.1 g/10 min and 1 g/10 min, said first polyethylene being obtained from a waste material; at least a second polyethylene having a density higher than 0.940 g/cm 3 , preferably not higher than 0.970 g/cm 3 , more preferably of between 0.942 g/cm 3 , and 0.965 g/cm 3 . Preferably, said coating layer is a cable external layer having a protective function. According to a further aspect, the present invention also relates to a process for producing a cable including at least one core comprising at least one transmissive element and at least one coating layer made from a coating material, said process comprising the steps of: providing at least a first polyethylene having a density not higher than 0.940 g/cm 3 , preferably not lower than 0.910 g/cm, more preferably of between 0.915 g/cm 3 and 0.938 g/cm 3 , and a Melt Flow Index (MFI), measured at 190° C. with a load of 2.16 Kg according to ASTM D1238-00 standard, of between 0.05 g/10 min and 2 g/10 min, preferably of between 0.1 g/10 min and 1 g/10 min, in a subdivided form, said first polyethylene being obtained from a waste material; providing at least a second polyethylene having a density higher than 0.940 g/cm 3 , preferably not higher than 0.970 g/cm 3 , more preferably of between 0.942 g/cm 3 and 0.965 g/cm 3 , in a subdivided form; conveying at least one core comprising at least one transmissive element into an extruding apparatus comprising a housing and at least one screw rotatably mounted into said housing, said housing including at least a feed hopper and at least a discharge opening; feeding said first and second polyethylenes to said extruding apparatus; melting and mixing said first and second polyethylenes in said extruding apparatus to form a homogeneous mixture; filtering said mixture; depositing said mixture onto said core comprising at least one transmissive element so as to obtain the coating layer. For the purpose of the present description and of the subsequent claims, the expression “in a subdivided form”, generally means a product of granular form, with an average diameter generally of between about 0.5 mm and about 5 mm, preferably of between 1 mm and about 4 mm, more preferably of between 1.5 mm and 3 mm. Preferably, said extruding apparatus is a single-screw extruder. Preferably said melting and mixing is carried out at a temperature of between 150° C. and 250° C., more preferably of between 120° C. and 230° C. According to one preferred embodiment, said first polyethylene and said second polyethylene are premixed before the step of feeding them to the extruding apparatus. According to one preferred embodiment, said coating material may further comprise a carbon black. According to a further preferred embodiment, said first polyethylene has a melting point lower than 130° C., preferably of between 100° C. and 125° C. According to a further preferred embodiment, said first polyethylene has a melting enthalpy (ΔH m ) of between 50 J/g and 150 J/g, preferably of between 80 J/g and 140 J/g. Said melting enthalpy (ΔH m ) may be determined by Differential Scanning Calorimetry with a scanning rate of 10° C./min: further details regarding the analysis method will be described in the examples given hereinbelow. Said first polyethylene may further comprise a carbon black. Generally, said carbon black may be present in the polyethylene in an amount higher than 2% by weight, preferably of between 2.5% by weight and 4.0% by weight, with respect to the total weight of the polyethylene. Said first polyethylene may be selected from low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), or mixtures thereof. Mixtures of low density polyethylene with a small amount of linear low density polyethylene, preferably an amount not higher than 15% by weight with respect to the total weight of the polyethylene, are particularly preferred. According to one preferred embodiment, said first polyethylene is present in the coating material in an amount of between 30% by weight and 90% by weight, preferably of between 40% by weight and 60% by weight, with respect to the total weight of the coating material. Examples of said first polyethylene which may be used according to the present invention and which are currently commercially available are the products coming from used agricultural polyethylene films (e.g. the products Alfaten® from Alfagran). According to one preferred embodiment, said second polyethylene has a Melt Flow Index (MFI), measured at 190° C. with a load of 2.16 Kg according to ASTM D1238-00 standard, of between 0.05 g/10 min and 2 g/10 min, preferably of between 0.1 g/10 min and 1 g/10 min. According to a further preferred embodiment, said second polyethylene has a melting point higher than 120° C., preferably of between 125° C. and 165° C. According to a further preferred embodiment, said second polyethylene has a melting enthalpy (ΔH m ) of between 125 J/g and 200 J/g, preferably of between 130 J/g and 185 J/g. Said melting enthalpy (ΔH m ) may be determined by Differential Scanning Calorimetry as disclosed above. According to a further preferred embodiment, said second polyethylene is a polyethylene obtained from waste material. Optionally, said polyethylene obtained from waste material comprises a small amount, preferably an amount not higher than 15% by weight with respect to the total weight of the polyethylene, of polypropylene. According to one preferred embodiment, said second polyethylene is present in the coating material in an amount of between 10% by weight and 70% by weight, preferably of between 40% by weight and 60% by weight, with respect to the total weight of the coating material. Examples of said second polyethylene which may be used according to the present invention and which are currently commercially available are the products DGDK-3364® Natural from Dow Chemical, or the products coming from used polyethylene bottles (e.g. from Breplast). In order to protect the coating material from UV degradation said coating material, as reported above, may further comprise carbon black. Preferably, the carbon black is added to the coating material in an amount of between 2% by weight and 5% by weight, preferably of between 2.5% by weight and 4.0% by weight, with respect to the total weight of the coating material. The carbon black may be added to the coating material as such or as a masterbatch in polyethylene. Masterbatch is particularly preferred. Other conventional additives may be added to the coating material according to the present invention such as, for example antioxidants, processing aids, lubricants, pigments, foaming agents, plasticizers, UV stabilizers, flame-retardants, fillers, thermal stabilizers, or mixtures thereof. Conventional antioxidants suitable for the purpose may be selected from antioxidants of aminic or phenolic type such as, for example: polymerized trimethyl-dihydroquinoline (for example poly-2,2,4-trimethyl-1,2-dihydroquinoline); 4,4′-thiobis-(3-methyl-6-t-butyl)-phenol; pentaerythryl-tetra-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]; 2,2′-thiodiethylene-bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], or the mixtures thereof. Conventional processing aids suitable for the purpose may be selected, for example, from: calcium stearate, zinc stearate, stearic acid, paraffin wax, or mixtures thereof. Conventional fillers suitable for the purpose may be selected, for example, from glass particles, glass fibers, calcinated clay, talc, or mixtures thereof. The coating material according to the present invention may be either crosslinked or non-crosslinked according to the required countries specifications. Preferably, said coating material is non-crosslinked. If crosslinking is carried out, the coating material comprises also a crosslinking system, of the peroxide or silane type, for example. It is preferable to use a silane-based crosslinking system, using peroxides as grafting agents. Examples of organic peroxides that may be advantageously used, both as crosslinking agents or as grafting agents for the silanes, are dicumyl peroxide, t-butylcumylperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexane, di-t-butylperoxide, t-butylperoxy-3,3,5-trimethyl-hexanoate, ethyl-3,3-di(t-butylperoxy)butyrate. Examples of silanes that may be advantageously used are (C 1 -C 4 )-alkyloxyvinylsilanes such as, for example, vinyldimethoxysilane, vinyltriethoxysilane, vinyldimethoxyethoxysilane. The crosslinking system may also comprise a cross-linking catalyst selected from those known in the art. In the case of crosslinking with silanes, for example, lead dibutyl dilaurate may be advantageously used. Said first polyethylene may be obtained from waste material as a product in subdivided form by means of processes known in the art. For example, said product in a subdivided form may be obtained by means of a process comprising the following steps: (a) sorting out the impurities (such as, for example, metal, paper, etc) optionally present in a waste material (for example, by feeding said waste material to a conveyor belt and manually sorting out the impurities); (b) feeding the waste material obtained in step (a) [(for example, by means of the same conveyor belt used in step (a)], to a mill obtaining flakes having an average diameter generally of between about 0.1 cm and about 2.0 cm; (c) washing the flakes obtained in step (b) in water and filtering the same in order to discard the impurities having a density higher than 1 kg/l; (d) drying the flakes obtained in step (c) (for example, in a drying apparatus) with warm and dry air; (e) feeding the dried flakes obtained in step (d) to an extruding apparatus comprising a housing and at least one screw rotatably mounted into said housing, including at least a feed hopper and a discharge opening; (f) melting and mixing said flakes obtaining a homogeneous mixture; (g) filtering and granulating the homogeneous mixture obtained in step (f) obtaining a product in a subdivided form; (h) cooling the product in a subdivided form obtained in step (g) (for example, in water); (i) drying the cooled product obtained in step (h) (for example, in a drying apparatus) with warm and dry air. Preferably, the homogeneous mixtures obtained in step (f) is fed to a second extruding apparatus to obtain a more homogeneous mixture. Preferably, said extruding apparatuses are single-screw extruders. Preferably, the granulation in step (g) may be carried out, by means of chopping or shredding the homogeneous mixture obtained in step (f) by means of cutting devices known in the art. BRIEF DESCRIPTION OF THE DRAWINGS Further details will be illustrated in the following, appended drawings, in which: FIG. 1 shows, in cross section, an electrical cable of the unipolar type according to one embodiment of the present invention; FIG. 2 shows, in cross section, an electrical cable of the tripolar type according to a further embodiment of the present invention; FIG. 3 shows, in perspective view, a length of cable with parts removed in stages, to reveal its structure according to a further embodiment of the present invention; FIG. 4 , shows, in cross section, an optical cable according to a further embodiment of the present invention; FIG. 5 , shows, in cross section, an optical cable according to a further embodiment of the present invention; FIG. 6 shows, in perspective view, a length of an optical cable with parts removed in stages, to reveal its structure according to a further embodiment of the present invention; FIG. 7 a and FIG. 7 b show respectively a side view and a partial plan view of a process line according to one embodiment of the present invention; FIG. 8 shows a full scale photograph of an extruded coating layer obtained from recycled polyethylene alone (sample (A)) and an extruded coating layer obtained from the coating material according to the present invention (sample (B)). DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1 , cable 1 comprises a conductor 2 , an internal insulating coating layer 3 and an external layer 4 which may be made according to the present invention. Referring to FIG. 2 , cable 1 comprises three conductors 2 , each one covered by an insulating coating layer 3 . The conductors 2 thus insulated are wound around one another and the interstices between the insulated conductors 2 are filled with a filler material that forms a continuous structure having a substantially cylindrical shape. The filler material 5 is preferably a flame-retarding material. An external layer 6 , which may be made according to the present invention, is applied, generally by extrusion, to the structure thus obtained. Referring to FIG. 3 , cable 11 comprises, in order from the centre outwards: a conductor 12 , an internal semiconducting layer 13 , an insulating coating layer 14 , an external semiconducting layer 15 , a metallic screen 16 , and an external layer 17 . The conductor 12 generally consists of metal wires, preferably of copper or aluminium, stranded together according to conventional techniques. The internal and external semiconducting layers 13 and 15 are extruded on the conductor 12 , separately or simultaneously with the insulating coating layer 14 . A screen 16 , generally consisting of electrically conducting wires or tapes, wound spirally, is usually arranged around the external semiconducting layer 15 . Said screen is then covered with an external layer 17 , which may be made according to the present invention. The cable may in addition be provided with an outer protective structure (not shown in FIG. 3 ), which mainly performs the function of mechanical protection of the cable against impact and/or compression. Said protective structure may be, for example, a metallic armour or a layer of expanded polymeric material as described in patent application WO 98/52197. FIG. 4 is a sectional view of an optical cable 1 a consisting of an external layer 2 a which may be made according to the present invention, a certain number of tubes 3 a of polymeric material within which are housed the optical fibres 4 a , normally embedded in a packing material 5 a which has the purpose of preventing the longitudinal propagation of water in case of accidental rupture; the tubes containing the optical fibres are wound around a central support 6 a normally made of glass-fiber reinforced plastic and capable of limiting the thermal contractions of the cable (the stranding may be of the continuous or alternate type, commonly called S-Z). Optionally, there may be inserted between the external layer 2 a and the tubes 3 a an interstitial packing material 7 a capable of penetrating into the interstices between the tubes and the coating, between one tube and the next, and between the tubes and the support, in order to limit the longitudinal propagation of water inside the cable. FIG. 5 is a sectional view of an optical cable similar to that described in FIG. 4 , with the difference that inside the external layer 2 a there is a tensile reinforcing layer 8 a (for example a glass fiber or polyaramid fiber such as the product known commercially as Kevlar®); additionally, the tubes 3 a containing the optical fibres are surrounded by a sheath of a polymeric material 2 b having one or more layers, which may be made according to the present invention Additionally, according to the embodiment shown in FIG. 5 , the central support comprises a core 6 a , made for example of glass-fiber reinforced plastic or similar materials, capable of limiting the thermal contractions of the cable, and a coating 6 b , made for example of polymeric material, such that it increases the diameter of the core to a value capable of receiving the desired number of tubes wound around it. FIG. 6 is a perspective view of an optical cable 11 a according to the present invention in which the optical fibres 13 a are located in housings in a central grooved core 12 a made of polymeric material, which if necessary may be in contact with a suitable packing 14 a ; the grooved core may optionally contain a central support made of glass-fiber reinforced plastic 15 a . The grooved core is therefore surrounded by a set of layers ( 16 a , 16 b ) at least one of which may be made according to the present invention, and by a tensile reinforcing layer 17 a which as been described above; optionally, the cable structure may also comprise a tape for the purposes of containment and/or protection of the fibers 18 a and a wet-expanding tape 18 b (for example a polyester or polyamide tape filled with wet-expanding material, such as sodium polyacrylate) for the purpose of limiting the longitudinal propagation of water inside the cable. FIGS. 1 , 2 , 3 , 4 , 5 and 6 show just some possible embodiments of a cable according to the present invention. Referring to FIG. 7 a and FIG. 7 b , the main steps of a processing line for producing cables in accordance with the present invention are shown in schematic form, said process comprising the following steps: a step of unwinding a core comprising at least one transmissive element from a feeding reel and conveying said core inside of the extrusion head of a given extruder; a step of feeding a first polyethylene and a second polyethylene forming the coating layer of said cable into said extruder; a step of melting and mixing said first and second polyethylenes within the extruder, followed by the steps of filtrating the obtained mixture and conveying the filtrated mixture into the extrusion head where the coating layer thus obtained is deposited around the aforesaid core; a step of cooling the cable thus produced, and a phase of collecting the finished cable on a reel. In the case where the coating material used is of a crosslinkable type, a crosslinking operation is provided upstream from the cooling stage. More specifically, FIG. 7 a represents a schematic side view of processing line 20 referred to above, and FIG. 7 b represents a partial plan view of said line 20 , in which the first stages of said process are shown. With reference to the aforesaid FIG. 7 a and FIG. 7 b , a core 21 comprising a conductor, for example a conductor made of copper, and an insulating coating layer, is unwound from a feeding reel 22 according to any known technique and conveyed towards the extrusion head of an extruder 23 , for example an extruder of the screw type turned by a motor of conventional type (not represented). In FIG. 7 b , a second feeding reel 22 ′, in non-operating position, which substitutes first reel 22 once the unwinding operation of core 21 from said first reel is completed, is shown. Also shown in FIG. 7 a is a system 24 consisting of a plurality of pulleys and gears whose purpose is to ensure a regular and continuous feeding of the core 21 to extruder 23 , especially at the stage where reel 22 is exhausted, and also a constant pull on core 21 , at a predefined speed, so as to ensure uniform extrusion of the coating layer onto the core 21 . In general the forward speed of the core is between 10 m/min to 1000 m/min. Simultaneously with the unwinding of the core 21 from feeding reel 22 , the first polyethylene, the second polyethylene and the conventional additives optionally present in the coating material referred to above, are fed into the inlet of extruder 23 in a known manner, for example by means of a hopper 25 . The first polyethylene, the second polyethylene and the conventional additives optionally present in the coating material, as reported above, may be premixed before being fed to the extruder, in a device upstream from the processing line represented in FIG. 7 a or FIG. 7 b . The premixing of the first polyethylene with the second polyethylene and with the conventional additives optionally present in the coating material, may be carried out, for example, in a Banbury mixer, in a twin-screw extruder, or during the process for obtaining the first polyethylene in a subdivided form above disclosed. Preferably, for the aim of the present invention, the first polyethylene, the second polyethylene and the conventional additives optionally present in the coating material, are premixed in the extruding apparatus used in step (e) of the process for obtaining the first polyethylene in a subdivided form above disclosed. Said first polyethylene, said second polyethylene, and the conventional additives optionally present in the coating material, as such or premixed, are charged inside of hopper 25 by means of suction nozzles which draw the material directly from packing containers. Within extruder 23 , said polyethylenes with the conventional additives optionally present, are homogeneously mixed and brought to plastification, i.e. to the molten state, by the work performed by the screw which pushes the coating material of the coating layer, imparting to it, moreover, the pressure necessary to overcome the pressure losses due to the presence of the various components which form the extrusion line. The obtained coating material is then subjected to a filtration step, which will be better described below, and in the final portion of extruder 23 it is deposited on the core 21 so as to obtain the desired coating layer. In the shown embodiment, this cable is then subsequently subjected to a suitable cooling cycle effected by moving the cable inside of a cooling channel 26 containing a suitable fluid, generally water at environmental temperature. Furthermore, in FIG. 7 a is shown a system 27 for multiple passage of the cable in cooling channel 26 , this system consisting, for example, of a storage unit for the processing line capable of guaranteeing an accumulation of cable on a scale sufficient to ensure a forward speed of the cable that is constant and equal to the preset value. This system 27 can also fulfil the function of making the cable thus obtained to follow a longer path within cooling channel in order to guarantee a more efficient cooling cycle of the cable itself. Finally, downstream from this cooling stage, the cable is dried by means of air blowers (not represented) and then wound onto a collector reel 28 and sent to a storage area. The filtration operation of the coating material, plasticized and rendered homogeneous by said screw, is performed by means of the positioning of a filter pack downstream from said screw, at the inlet to a connecting duct which links the extrusion head with the housing within which the extrusion screw is moved. The filter pack may comprises one or more filter screens placed in series, generally three or even more filter screens, which are supported on a filter support plate 32 . It should be emphasized that the choice of the number and the type of the filter screens to be used in the filtration section of a production process is markedly influenced by the chemical and physical properties of the coating material to be subjected to filtration. The process for producing a cable disclosed in FIG. 7 a and in FIG. 7 b , is described with reference to the case in which it is required to make a single core (unipolar) energy cable illustrated in FIG. 1 above disclosed. If different energy cable, or optical cable, or mixed electro-optical cable, are to be produced, the process above described, may be suitably modify as well known in the art. The present invention is further described in the following examples, which are merely for illustration and must not be regarded in any way as limiting the invention. Examples 1-5 Preparation of the Coating Materials Table 1 shows the characterization of the components used in the examples. The components were the following: recycled PE: mixture of 90% by weight of low density polyethylene and 10% by weight of linear low density polyethylene, comprising 2.5% by weight of carbon black, coming from used agricultural films; DGDK-3364® Natural: high density polyethylene from Dow Chemical; recycled HDPE: high density polyethylene comprising 10% by weight of isotactic polypropylene coming from used bottles (Breplast); DFDG 6059® Black: linear low density cable jacketing compound from Dow Chemical. The Melt Flow Index (MFI) was measured at 190° C. with a load of 2.16 Kg according to ASTM D1238-00 standard. The density was measured, at 23° C., according to CEI EN 60811-1-3 standard. The melting point and the melting enthalpy (ΔH m ) were measured by Mettler DSC instrumentation (second melting value) with a scanning rate of 10° C./min (instrument head type DCS 30; microprocessor type PC 11, Mettler software Graphware TA72AT.1). The carbon black content was determined by Mettler TGA instrumentation using the following method: heating from 20° C. to 85° C. at a scanning rate of 20° C./min in N 2 (60 ml/min); leaving at 850° C. for 1 min in N 2 (60 ml/min); leaving at 850° C. for 10 min in air (60 ml/min). The obtained data are given in Table 1. TABLE 1 Melting Melting Carbon Density point enthalpy black COMPONENT MFI (g/cm 3 ) (° C.) (J/gr) (%) Recycled PE 0.45 0.920 121 110 2.5 DGDK-3364 ® 0.70 0.945 127 180 — Natural Recycled 0.21 0.960 131 156 — HDPE DFDG 6059 ® 0.60 0.932 — — 2.6 Black The coating materials given in Table 2 (the amounts of the various components are expressed in % by weight with respect to the total weight of the coating material) were prepared as follows. Agricultural films were fed to a conveyor belt and the impurities present (metal, paper, etc) were manually sorted out. Subsequently, the films were fed, by means of the same conveyor belt, to a mill obtaining flakes having an average diameter generally of between about 0.1 cm and about 2.0 cm. The obtained flakes were washed in water and subsequently filtered in order to discard the impurities having a density higher than 1 kg/l. The flakes were subsequently dried in a drying apparatus with warm and dry air. The dried flakes so obtained, Vibatan® PE black 99415, Anox® HB, DGDK® 3364, recycled HDPE, in the amount given in Table 2, were fed to a first single-screw extruder in 32 D configuration, with rotary speed of about 60 rev/min, with temperature in the various zones of the extruder of 215-225-225-220-225-225° C., the temperature of the extrusion head was 220° C. The obtained mixture was filtered (filter mesh: 180 μm) and subsequently fed to a second single-screw extruder in 32 D configuration, with rotary speed of about 100 rev/min, with temperature in the various zones of the extruder of 128-167-167-177-190-206° C., the temperature of the extrusion head was 200° C. The obtained mixture was filtered (filter mesh: 110 μm) and subsequently granulated with a cutting device having a rotatory blades obtaining granules having an average diameter of about 4 mm. The obtained granules were then cooled in water and dried in a drying apparatus with warm and dry air. TABLE 2 EXAMPLE 1 (*) 2 3 4 5 (*) Recycled PE 100 56 56 51 — Vibatan ® PE Black — 3 3 3 — 99415 Anox ® HB — 1 1 1 — DGDK-3364 ® — — 40 — — Natural Recycled HDPE — 40 — 45 — DFDG-6059 ® Black — — — — 100 (*): comparative. Vibatan ® PE Black 99415: 40% dispersion of carbon black in low density polyethylene (VIBA Group); Anox ® HB: 2,2,4-trimethyl-1,2-dihydroquinoline polymer (Great Lakes Chemical). The obtained granules were subjected to the following analysis. Hot Pressure Resistance The hot pressure resistance test at 115° C. was determined according to IEC 60811-3-1 standard. For this purpose, plates with thickness of 1 mm were prepared by compression moulding at 190° C. and 20 bar after preheating for 10 min at the same temperature. The obtained plates were subjected to a temperature of 115° C., under a weight of 475 g, for 6 hours. After, their residual thickness was measured. The resistance to hot pressure test is the residual thickness expressed as a percentage of the initial thickness. The obtained data are given in Table 3. Hardness The Shore D hardness was determined according to ASTM D2240-03 standard. For this purpose, plates with thickness of 8 mm were prepared according to the process above disclosed. The obtained data are given in Table 3. Environmental Stress Crack Resistance (ESCR) The ESCR was determined according to D-1693 standard, Cond. A. For this purpose, plates with thickness of 3 mm and cut thickness of 0.65 mm in the case of the coating material of Example 1 (comparative), and with thickness of 2 mm and cut thickness of 0.4 mm in the case of the coating materials of Examples 2-4 according to the present invention and of Example 5 (comparative), were prepared according to the process above disclosed. The measurement was carried out at a temperature of 50° C. in the presence of 10% Igepal solution. The obtained data are given in Table 3. TABLE 3 EXAMPLE 1 (*) 2 3 4 5 (*) Hot pressure 30 97.5 96 97 90 resistance (%) ESCR <24 96 96 72 >500 (hours) Shore D 50 55 55 57 56 (*): comparative. The data above reported show that the coating materials according to the present invention (Examples 2-4) have hot pressure resistance and Shore D hardness values higher with respect to those obtained from recycled polyethylene alone (Example 1) and comparable or even higher with respect to those obtained from a commercial product (Example 5). With regard to the stress cracking resistance, the coating material according to the present invention shows improved values with respect to those obtained from recycled polyethylene alone. Examples 6-10 Small cables were then prepared by extruding the coating materials according to Examples 1-5 onto a single red copper wire with a cross-section of 1.5 mm 2 , so as to obtain a 3.4 mm thick cable. The extrusion was carried out by means of a 45 mm Bandera single-screw extruder in 25 D configuration, with rotary speed of about 45 rev/min. The speed line was about 10 m/min, with temperature in the various zones of the extruder of 115-160-190-190-180° C., the temperature of the extrusion head was 180° C. Samples were taken with hand punches from the extruded layer to measure its mechanical properties in accordance with CEI 20-34, section 5.1, with an Instron instrument at a draw speed of 25 mm/min. The obtained data are given in Table 4. TABLE 4 EXAMPLE 6 (*) 7 8 9 10 (*) Stress at 15.8 19.4 18.9 19.8 20.9 break (MPa) Elongation at 515 622 629 650 710 break (%) (*): comparative. The data above reported show that the coating materials according to the present invention (Examples 7-9) have mechanical properties higher with respect to those obtained from recycled polyethylene alone (Example 6) and comparable to those obtained from a commercial product (Example 10). Furthermore, two samples obtained as reported above were also examined in order to determine the presence of defects on the surface of the extruded coating layers: the enclosed photo (FIG. 8 —full scale) shows that the extruded coating layer obtained from recycled polyethylene alone [Example 6—sample (A)] showed the presence of defects on its surface (e.g. small agglomerates are present); on the contrary, the extruded coating layers obtained from the coating material according to the present invention [Examples 9—sample (B)] did not show any detectable defects on its surface.

A cable including at least one core having at least one transmissive element and at least one coating layer made from a coating material, wherein the coating material has at least a first polyethylene having a density not higher than 0.940 g/cm 3 , preferably not lower than 0.910 g/cm 3 , more preferably 0.915 g/cm 3 to 0.938 g/cm 3 , and a Melt Flow Index (MFI), measured at 190° C. with a load of 2.16 Kg according to ASTM D1238-00 standard, of 0.05 g/10′ to 2 g/10′, preferably 0.1 g/10′ to 1 g/10′; the first polyethylene being obtained from a waste material; at least a second polyethylene having a density higher than 0.940 g/cm 3 , preferably not higher than 0.970 g/cm 3 , more preferably 0.942 g/cm 3 to 0.965 g/cm 3 . Preferably, the coating layer is a cable external layer having a protective function.

This application is the national phase of International Application No. PCT/CN2011/083179, titled “MAINTENANCE TOOL FOR INSULATOR OF DIRECT CURRENT TRANSMISSION LINE”, filed on Nov. 29,2011, which claims priority to Chinese patent application No. 201020685182.8 titled “MAINTENANCE TOOL FOR INSULATOR OF DIRECT CURRENT TRANSMISSION LINE” and filed with State Intellectual Property Office of PRC on Dec. 28, 2010, the entirety of which are incorporated herein by reference in its entirety. FIELD OF THE INVENTION The present application relates to the field of the electric power, and particularly to a maintenance tool for an insulator on a direct current transmission line. BACKGROUND OF THE INVENTION As the power grid construction of China is improved increasingly, the extra high voltage transmission line becomes the backbone of the power grid frame of China, which also has a higher requirement on the maintenance work. Especially as the 660 kV grade of direct current transmission line is firstly applied in China, in order to ensure the normal operation of the transmission line and that troubles found during the operation of the transmission line can be solved timely, to thereby ensure the safe operation of the direct current transmission line, it is necessary to develop a set of tools for the maintenance of the transmission line in operation. One of the primary contents of the maintenance work of the transmission line is to repair and replace an insulator. Most high voltage transmission lines are supported on a crossarm via an insulator which plays a fundamental role of supporting the wire and preventing the current from returning to the ground in the aerial transmission lines. The 660 kV grade of direct current transmission line, compared with the extra high voltage and ultrahigh voltage transmission lines in operation currently, employs a different material, for example, the wire is the aluminum conductor steel reinforced of 4×JL/G3A-1000/45 mm 2 , and the distance between the electrodes of the wire is 18 m. The linear insulator is a V-type composite insulator which has a length of 8.5 m in the light polluted area and 9.2 m in the heavy polluted area. And the tension insulator string is a 550 kN double porcelain insulators in parallel. Influenced by the length of the string of the insulators and the electric clearance, the tower head for carrying the insulators and the transmission lines has a large size, and affected by the project, the vertical load of the lines increases accordingly, which causes the change of the tension, the length and the like, thereby has a higher requirement on the replacement of the insulator in aspects such as the tension and the length. At present, maintenance tools for the transmission line at a voltage grade below 500 kV have been more perfect, however, due to the increase of the voltage grade, the diameter of the transmission line and the length of the insulator string are increased. Thus the maintenance tools have been far from the requirements for the replacement. SUMMARY OF THE INVENTION It is provided according to one technical problem to be solved by the present application a maintenance tool for an insulator on a direct current transmission line. In view of this, the present application adopts the following technical solutions. A maintenance tool for an insulator on a direct current transmission line including a clamping device configured to be clamped at two ends of the insulator and a tension device configured to be connected between the clamping device. The clamping device includes: a closed clamp configured to be clamped on the insulator, a single string clamp fixed on a towing plate, and a wire end clamp fixed on a wire end yoke plate. The tension device is a mechanical transmission screw rod. When replacing a first insulator at a crossarm end, a cooperation of the single string clamp, the closed clamp and the tension device is used. When replacing a first insulator at a wire end, a cooperation of the wire end clamp, the closed clamp and the tension device is used. When replacing a single insulator or multiple insulators in the middle portion, or a long rod insulator, two closed clamps and two tension devices are sufficient for the replacing of the insulator. The structure of the closed clamp is that: the closed clamp includes a closed clamp main body and an upper cover arranged on the closed clamp main body. One end of the upper cover is moveably connected to the closed clamp main body via a pin shaft, and the other end of the upper cover is fixedly connected to the closed clamp main body via a bolt. A through hole for receiving the insulator is formed between the closed clamp main body and the upper cover. Each of two end portions of the main body is provided with a pin hole for connecting the tension device; and an inner side of the pin hole is provided with a lifting device for lifting the insulator. The improvements of the closed clamp lie in that: the lifting device is a support fixed on the closed clamp main body, and the support is provided with a pulley wheel for hanging a cable; the lifting device is configured for lifting a heavy long rod insulator in replacing the long bar insulator. The structure of the single string clamp is that: the single string clamp includes a single string clamp main body. A wing plate is arranged on each of two sides of the single string clamp main body, and an end portion of the wing plate is provided with a pin hole for connecting the tension device. A lower portion of the main body is fixedly connected with an insert plate having a clamping groove, and a lower end portion of the insert plate is provided, at a position corresponded to that of a connecting hole on the towing plate, with a pin hole. The structure of the wire end clamp is that: the wire end clamp includes a wire end clamp main body and a plate turning clamp arranged on the wire end clamp main body. One end of the plate turning clamp is movably connected with the wire end clamp main body via a pin shaft, and the other end of the plate turning clamp is fixedly connected with the wire end clamp main body via a bolt. A through hole for receiving a wire end yoke plate is formed between the wire end clamp main body and the plate turning clamp. Each of the wire end clamp main body and the plate turning clamp is provided with a hole corresponded to a nut on the wire end yoke plate. Each of two end portions of the wire end clamp main body is movably connected with a steel connector for connecting the tension device. The improvement of the tension device is that: the tension device includes a mechanical transmission screw rod and a hydraulic device connected to one end of the mechanical transmission screw rod via a locating pin or an insulation pulling rod. With the above technical solutions, the present application has the following technical progresses. Based on characters of the direct current transmission line such as the tower-shaped structure, the hanging manner of the insulator string and parameters of the earth wire, the present application provides a maintenance tool for live or power outage maintaining of the long rod insulator, a single porcelain insulator or multiple porcelain insulators on a 660 kV direct current transmission line. The maintenance tool has advantages such as a proper structure, a high overall strength, a small volume, a light weight and a reliable operation, thereby providing a reliable guarantee for the safe commissioning as well as the routine maintenance after the commissioning of the 660 kV direct current transmission line. The arrangement of the lifting device on the closed clamp enables the operator to lift a heavy long rod insulator during the replacing operation of the long rod insulator, which reduces the labor intensity and increases the working efficiency of the operator. The tension device is configured to be a composition of the mechanical transmission screw rod and the hydraulic device for shortening or enlarging idle strokes of the clamps, which overcomes the disadvantages that the hydraulic transmission system has a slow transmission speed when being used for transmitting a large mechanical load, and reduces the working time of the operator when working high above the ground. Besides, the structure has a function of mutual protection, that is, when one of the transmission mechanisms fails, the normal work of the other transmission mechanism would not be influenced, thereby the operation reliability is greatly improved. Further, since the tension device is assembled from separate structures, when the tension device is in idle, the separate structures may be stored separately, thereby facilitating the replacement and the maintenance. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a closed clamp; FIG. 2 is a top view of a closed clamp; FIG. 3 is a front view of a single string clamp; FIG. 4 is a schematic structural view of a wire end clamp; FIG. 5 is a bottom view of FIG. 4 ; FIG. 6 is a connecting relationship diagram for replacing a long rod insulator according to the present application; FIG. 7 is a connecting relationship diagram for replacing a first insulator at a wire end according to the present application; and FIG. 8 is a connecting relationship diagram for replacing a first insulator at a crossarm end according to the present application. REFERENCE NUMBERS IN THE FIGURES 1 . closed clamp, 11 . closed clamp main body, 12 . upper cover, 13 . support, 14 . pulley wheel, 2 . single string clamp, 21 . single string clamp main body, 22 . wing plate, 23 . clamping groove, 24 . insert plate, 3 . wire end clamp, 31 . wire end clamp main body, 32 . plate turning clamp, 33 . steel connector, 4 . mechanical transmission screw rod, 5 . hydraulic device, and 6 . insulation pulling rod. DETAILED DESCRIPTION The present application will be illustrated in detail hereinafter in conjunction with the accompanying drawings and the embodiments. A maintenance tool for an insulator on a direct current transmission line includes a clamping device configured to be clamped at two sides of the insulator and a tension device connected between the clamping device. The clamping device includes a closed clamp 1 , a single string clamp 2 and a wire end clamp 3 . The clamping device is made of a TC4 titanium alloy material, and has characters including a high strength, a good plasticity, a light weight, a small volume, a high load bearing capacity and facilitates working high above the ground. The closed clamp is clamped on a steel cover of the insulator, the structure of which is shown in FIG. 1 and FIG. 2 . The closed clamp includes a closed clamp main body 11 and an upper cover 12 arranged on the closed clamp main body. One end of the upper cover is movably connected with the closed clamp main body via a pin shaft, and the other end of the upper cover is fixedly connected with the closed clamp main body via a bolt. A through hole for receiving the insulator is formed between the closed clamp main body and the upper cover. Each of two end portions of the main body is provided with a pin hole for connecting the tension device, and an inner side of the pin hole is provided with a lifting device for lifting the insulator. The lifting device is configured as a support 13 fixed on the closed clamp main body, and a pulley wheel 14 for hanging a cable is provided on the support. The single string clamp is fixedly connected on a towing plate, the structure of which is shown in FIG. 3 . The single string clamp includes a single string clamp main body 21 , a wing plate 22 and an insert plate 24 . The wing plate 22 is provided at each of two sides of the single string clamp main body 21 , and an end portion of the wing plate is provided with a pin hole for connecting the tension device. The insert plate 24 is fixedly connected at a lower portion of the single string clamp main body 21 , a lower portion of the insert plate 24 is formed with a clamping groove 23 , and a lower end portion of the insert plate is provided, at a position corresponded to that of a connecting hole on the towing plate, with a pin hole. The wire end clamp is fixed on a wire end yoke plate, as shown in FIG. 4 and FIG. 5 . The wire end clamp includes a wire end clamp main body 31 and a plate turning clamp 32 . The plate turning clamp 32 is arranged on the wire end clamp main body, one end of the plate turning clamp is movably connected with the wire end clamp main body 31 via a pin shaft, and the other end of the plate turning clamp is fixedly connected with the wire end clamp main body via a bolt. A through hole for receiving a wire end yoke plate is formed between the wire end clamp main body and the plate turning clamp. Each of the wire end clamp main body 31 and the plate turning clamp 32 is provided with a hole corresponded to a nut on the wire end yoke plate. Each of two end portions of the wire end clamp main body 31 is movably connected with a steel connector 33 for connecting the tension device. The tension device is connected between the closed clamp and the wire end clamp or between the closed clamp and the single string clamp, and the tension device is a combination of a mechanical transmission screw rod 4 and a hydraulic device 5 . The mechanical transmission screw rod is connected to the hydraulic device via an insulation pulling rod 6 . First Embodiment In a case that the present application is use for replacing a single insulator, multiple insulators in the middle portion or a long rod insulator on a 660 kV direct current transmission line, two closed clamps and two tension devices are sufficient, as shown in FIG. 6 . The upper cover of the closed clamp is opened, and is rotated to one side of the closed clamp main body about a pin shaft. Then the closed clamp is clamped on a steel cover at one of two ends of the insulator, and then the upper cover is covered to its original position. Then the upper cover and the closed clamp main body is fixedly connected via a bolt, thereby the closed clamp is fixedly connected on the insulator. Then the mechanical transmission screw rods and the hydraulic devices of the two tension devices are respectively connected to pin holes at ends of the two closed clamps, and then the insulation pulling rod 6 is connected between the mechanical transmission screw rod and the hydraulic device, so as to tension the insulator in the case that the insulator is long. After the connecting operation, the screw rod is tightened or the hydraulic device is actuated to thereby tension the closed clamps, such that the insulator is relaxed and no tension is applied thereon, and thus the insulator may be replaced. The lifting device on the closed clamp may be used to lift the insulator in cases that the insulator is heavy, which can save the labor resource and improve the safety of the operation. Second Embodiment When replacing a first insulator at a wire end on a 660 kV direct current transmission line, a composition of the wire end clamp, the closed clamp and the tension device is used, as shown in FIG. 7 . The difference between the second embodiment and the first embodiment lie in that: one closed clamp is clamped on the steel cover of the first insulator at the wire end; then the plate turning clamp of the wire end clamp is rotated to one side of the wire end clamp main body about a pin shaft such that the wire end yoke plate is clamped between the wire end clamp main body and the plate turning clamp, then the nut on the wire end yoke plate is inserted into the bolt hole of the wire end clamp; and then the other end of the plate turning clamp is fixedly connected with the wire end clamp main body via a bolt; next the mechanical transmission screw rod and the hydraulic device of the tension device is connected between the closed clamp and the wire end clamp, and the insulation pulling rod is connected between the mechanical transmission screw rod and the hydraulic device, thereby the insulator can be tensioned in a case that the insulator is long. In cases that the first insulator is near to the wire end yoke plate, the tension device may only includes the mechanical transmission screw rod or the hydraulic device. Third Embodiment When replacing a first insulator at a crossarm end on a 660 kV direct current transmission line, a composition of the single string clamp, the closed clamp and the tension device is used, as shown in FIG. 8 . The difference between the third embodiment and the second embodiment lie in that, one closed clamp is mounted on the steel cover of the first insulator at the crossarm end; then the insert plate, having the clamping groove, of the single string clamp is mounted on the towing plate such that the connecting hole on the towing plate is aligned with the pin hole of the single string clamp, then a bolt is passed through the holes such that the single string clamp is fixedly connected with the towing plate.

A maintenance tool for an insulator of a direct current transmission line comprises clamping devices and a tensioning device. The clamping devices are mounted at the two sides of the insulator through clamping, and the tensioning device is connected between the clamping devices. The clamping devices comprise a closed clamp ( 1 ), a single serial clamping device ( 2 ) and a wire end clamping device ( 30 ). The clamping device has advantages such as strong overall strength and bearing capacity, small size, light weight, and reliable working, and can be applied to replacement of various insulators on the direct current transmission line, reliably ensuring safe commissioning and regular maintenance of transmission lines.

APPLICATION CROSS REFERENCE This application claims the priority benefit of Provisional Application Ser. No. 60/319,189 filed Apr. 16, 2002 the teachings of which are hereby incorporated by reference. BACKGROUND OF INVENTION The invention relates to a peptide compound having an improved binding affinity to somatostatin receptors, comprising a somatostatin analogue as the peptide and a chelating group covalently linked to the N-terminal free amino group of said peptide Such peptide compounds and their radiolabelled derivatives can be used for therapy of somatostatin—receptor positive tumors. Detectably labeled somatostatin—peptide compounds are also useful for in vivo imaging. See in this respect the patent publications of Albert et al. (U.S. Pat. No. 5,753,627; U.S. Pat. No. 5,776,894), of Krenning et al. (U.S. Pat. No. 6,123,916), of De Jong et al. (WO 00/18440), and of Srinivasan et al. (U.S. Pat. Nos. 5,804,157; 5,830,431). Albert et al., disclose complexed somatostatin peptides for in vivo imaging of somatostatin receptor—positive tumors, which peptides are derived from somatostatin analogues, carrying an optionally substituted phenylalanine residue or a beta- or 2-naphthylalanine residue in its 3-position. Selective internal tumor therapy with radiolabelled peptides has become very important in nuclear medicine in the past years. Especially somatostatin derivatives have been successfully applied in the clinic for tumor diagnosis and therapy, showing that the principle of receptor targeting is working in practice. For more than four years already much experience has been gained in clinical trials with the use of 90 Y—labeled DOTA-[Tyr 3 ]-octreotide (DOTA-TOC) for tumor therapy (M. de Jong: Eur. J. Nucl. Med. 26, 1999, 693–698). Yet DOTA-TOC only shows high affinity to the somatostatin receptor subtype 2 (sst 2), whereas the affinity to other somatostatin subtypes, in particular sst 3 and sst 5, which are found also in a variety of tumors, is too low to contribute essentially to tumor targeting. For example, most thyroid tumors express these last-mentioned somatostatin receptor subtypes, but have only low levels of sst 2 (E. B. Forssell-Aronsson et al.: J. Nucl. Med. 41, 2000, 636–642). SUMMARY OF THE INVENTION It is the objective of the present invention to provide a peptide compound which has a considerable binding affinity to a plurality of somatostatin receptor subtypes, compared with the above known somatostatin peptides. It is an additional advantage if such a peptide compound should have a substantially improved overall affinity to somatostatin receptors. On account of its multispecificity, such a peptide compound, in particular after labeling with a suitable radionuclide, could be therapeutically used for treating a broader variety of tumors. In addition, after labeling with a suitable detectable element, such a peptide compound should have an improved suitability for in vivo detecting and localizing tissues, in particular tumors and metastases thereof, carrying somatostatin receptor types in varying levels. This objective can be achieved, according to the present invention, by a peptide compound as defined herein, wherein said somatostatin analogue carries an 1-naphthylalanine or a 3-benzothienylalanine residue in its 3-position. It has been found, that the new peptide compounds of the invention have an unexpectedly high affinity to a plurality of somatostatin receptor subtypes. This favorable binding affinity makes the new peptide compounds promising candidates both for diagnosis, after labeling, and for tumor therapy. Internalization experiments show a substantially increased internalization rate. Biodistribution experiments in vivo show that the labeled new peptide compounds of the invention have a significantly higher tumor uptake than known somatostatin peptide derivatives. More in particular, the present invention relates to a new peptide compound as defined above, wherein the peptide is a somatostatin analogue of the general formula H-(A 0 ) n -A 1 -cyclo[Cys 2 -A 3 -A 4 -A 5 -A 6 -Cys 7 ]-A 8   (I) wherein: n is 0 or 1, A 0 is optionally halogenated Tyr or Phe, A 1 is optionally halogenated Tyr, or optionally halogenated or methylated Phe or Nal, A 3 is 1-Nal or 3-benzothienylalanyl, A 4 is Trp, optionally N-methylated in its side-chain, A 5 is Lys, optionally N-methylated in its side-chain, A 6 is Thr, Val, Ser, Phe or Ile, and A 8 is Thr, Trp or Nal, wherein the terminal carboxy group may be modified to an alcohol or an, optionally C1–C3 alkylated, amide group. Suitable examples of the above new somatostatin analogues of formula I are: H-(D)Phe-cyclo[Cys-1-Nal-(D)Trp-Lys-Thr-Cys]-Thr-ol  (1) H-(D)Nal-cyclo[Cys-1-Nal-(D)Trp-Lys-Val-Cys]-Thr-NH 2   (2) H-(D)Phe-cyclo[Cys-(L) 3 -benzothienylalanyl-(D)Trp-Lys-Thr-Cys]-Thr-ol  (3) The above examples are covered by the general formula II, encompassing preferred somatostatin analogues: H-(Á 0 ) n -(D)Á 1 -cyclo[Cys 2 -(L)A 3 -(D)Trp 4 -Lys 5 -Á 6 -Cys 7 ]-Á 8   (II) wherein: n is 0 or 1, Á 0 is optionally halogenated Tyr, Á 1 is optionally halogenated Tyr, or Phe, or Nal, A 3 is 1-Nal or 3-benzothienylalanyl, Á 6 is Thr or Val, and Á 8 is Thr-ol, Thr-OH or Thr-NH 2 . The inventors have already disclosed results of the above labeled compound (1) of their invention at two Symposia, viz. at Jun. 11–15, 2001, and at Aug. 26–29, 2001. These presentations have been published as Symposium Abstracts in J. Labeled Cpd. Radiopharm. 44, Suppl. 1 (2001), 5697–5699, and in Eur. J. Nucl. Med. 28/8, OS 24 (2001), 966, respectively. The peptide compound according to the invention comprises a chelating group covalently linked to the N-terminal free amino group of the peptide. Various well-known chelating groups can be used, for example, those selected from: (i) N 2 S 2 -, N 3 S- and N 4 -tetradentate ring structure containing groups, (ii) isocyanate, carbonyl, formyl, diazonium, isothiocyanate and alkoxycarbimidoyl containing groups, (iii) groups derived from N-containing di- and polyacetic acids and their derivatives, and from (iv) 2-iminothiolane and 2-iminothiacyclohexane containing groups. The chelating groups sub (iii) above are preferred, encompassing chelating groups derived from ethylenediamine tetraacetic acid (EDTA), diethylenetriamine pentaacetic acid (DTPA), ethyleneglycol-OO′-bis(2-aminoethyl)-N,N,N′,N′-tetraacetic acid (EGTA), N,N′-bis(hydroxybenzyl)ethylenediamine-N,N′-diacetic acid (HBED), triethylenetetramine hexaacetic acid (TTHA), substituted EDTA or DTPA, 1,4,7,10-tetraazacyclododecane-N,N′, N″,N′″-tetraacetic acid (DOTA), 1,4,7-triazacyclonane-1,4,7-triacetic acid (NOTA) or 1,4,8,11-tetraazacyclotetradecane-N,N′,N″,N′″-tetraacetic acid (TETA). The method of linking the chelating group to the somatostatin analogue for obtaining the peptide compound of the invention is generally known in the art. The synthesis of the peptide compound having the above chelating group sub (iv) is described in WO 89/07456. Generally, for the purpose in view, the peptide compound of the invention is labeled with a detectable element selected from gamma- or positron-emitting radionuclides, Auger-electron-emitting isotopes and paramagnetic ions of nonradioactive elements, or with a therapeutic radionuclide. Suitable detectable elements for imaging purposes are gamma- or positron-emitting radionuclides, selected from the group consisting of 99m Tc, 203 Pb, 66 Ga, 67 Ga, 68 Ga, 72 As, 111 In, 113m In, 97 Ru, 62 Cu, 64 Cu, 52 Fe, 51 Cr, 24 Na, 157 Gd, 52m Mn, 162 Dy, 123 I, 131 I, 75 Br and 76 Br, or paramagnetic ions of elements, selected from the group consisting of nonradioactive Gd, Fe, Mn and Cr. In addition to the use of radioisotopes as detectable elements, which enables in vivo detection by a gamma camera, paramagnetic ions of nonradioactive elements, such as Gd, Fe, Mn or Cr, preferably of Gd, can be used, viz. for in vivo detection by MRI. For therapeutic purposes the compounds of the invention can advantageously be labeled with therapeutic radionuclides, selected from the group consisting of 186 Re, 188 Re, 77 As, 90 Y, 67 Cu, 169 Er, 121 Sn, 127 Te, 142 Pr, 143 Pr, 198 Au, 109 Pd, 165 Dy, 177 Lu, 161 Tb, 211 At, 123m Rh, 111 In and 153 Sm. Chelation of the above metal isotopes can easily be effected in a manner known per se for related compounds, for example, by bringing the peptide compound of the invention in contact with a compound, often a salt, of the desired isotope in a suitable solvent or diluent, if desired at higher temperature. The preparation of radioactive-halogen labeled peptide compounds according to the present invention can be carried out by a method as described for related compounds in the above-mentioned WO 00/18440, in order to introduce the desired halogen radionuclide into an aromatic nucleus in position 0 or 1 of the peptide. This labeling can conveniently be performed by introducing a halogen atom or a radioactive halogen atom into an radioactive nucleus, preferably an activated aromatic nucleus such as tyrosyl, present in the above position in the peptide compound, if necessary followed by exchange with the desired halogen radionuclide. The radiohalogenation reaction is preferably performed by reacting the peptide compound with a solution of an alkali metal radionuclide selected from 123 I − , 131 I − , 211 At − , 75 Br − and 76 Br − under the influence of a halide-oxidizing agent, such as chloramine T or iodogen. Alternatively, the above substitution reaction can be carried out with nonradioactive halogen, after which halo-exchange with radioactive halogen is performed, e.g. as described in European patent 165630. The present invention further relates to a pharmaceutical composition, comprising in addition to a pharmaceutically acceptable carrier and, if desired, at least one pharmaceutically acceptable adjuvant, as the active substance a labeled peptide compound as defined above, or a pharmaceutically acceptable salt thereof. Such pharmaceutical compositions can be used for diagnostic purposes; then the peptide compounds are provided with detectable elements as described above. If the compositions are intended for tumor therapy, advantageously the above-mentioned therapeutic radionuclides can be used for labeling the peptide compounds. The present invention also relates to a method for detecting and localizing tissues having somatostatin receptors in the body of a warm-blooded living being, This diagnostic method comprises (i) administering to said being a pharmaceutical composition, labeled with a suitable detectable element, as defined above, comprising the active substance in a quantity sufficient for external imaging, and thereupon (ii) subjecting said being to external imaging to determine the targeted sites in the body of said being in relation to the background activity, in order to allow detection and localization of said tissues in said body. The present invention further relates to a method for the therapeutic treatment of tumors, having on their surface somatostatin receptors, in the body of a warm-blooded living being, which comprises administering to said being a pharmaceutical composition labeled with a suitable therapeutic radionuclide, as defined above, comprising the active substance in a quantity effective for combating or controlling tumors. It is sometimes hardly possible to put the ready-for use radiolabelled composition at the disposal of the user, in connection with the often poor shelf life of the radiolabelled peptide compound and/or the short half-life of the radionuclide used. In such cases the user can carry out the labeling reaction with the radionuclide in the clinical hospital or laboratory. For this purpose the various reaction ingredients are then offered to the user in the form of a so-called “kit”. It will be obvious that the manipulations necessary to perform the desired reaction should be as simple as possible to enable the user to prepare from the kit the radioactive-labeled composition by using the facilities that are at his disposal. Therefore the invention also relates to a kit for preparing a radiopharmaceutical composition. Such a kit according to the present invention may conveniently comprise a peptide compound as defined hereinbefore, viz. derived from a somatostatin analogue carrying an 1-naphthylalanine or 3-benzothienylalanine residue in its 3-position, to which substance, if desired, an inert pharmaceutically acceptable carrier and/or formulating agents and/or adjuvants are added, (ii) a solution of a radionuclide compound selected from the group consisting of 99m Tc, 203 Pb, 66 Ga, 67 Ga, 68 Ga, 72 As, 211 At, 111 In, 113m In, 97 Ru, 62 Cu, 64 Cu, 52 Fe, 52m Mn, 51 Cr, 24 Na, 157 Gd, 186 Re, 188 Re, 77 As, 90 Y, 67 Cu, 169 Er, 121 Sn, 127 Te, 142 Pr, 143 Pr, 198 Au, 109 Pd, 165 Dy, 177 Lu, 161 Tb, 123m Rh and 153 Sm, and (iii) instructions for use with a prescription for reacting the ingredients present in the kit. The kit according to the invention preferably comprises a peptide compound derived from a somatostatin analogue of the general formula I, wherein the symbols have the meanings given hereinbefore. BRIEF DESCRIPTION OF DRAWINGS For a better understanding of the present invention, reference may be made to the accompanying drawing win which: FIG. 1 illustrates a graphical representation of a rat study showing that tumor and non- tumor tissue uptake is receptor specific (except for kidneys) and specifically discloses observed uptake of 111 In-DOTA-[1-Na 3 ]-TATE peptide in somatostatin receptor expressing tissues being blocked by coinjection of non-radioactive, competitor, somatostatin analogs that have various receptor subtype specificity. DETAILED DESCRIPTION OF THE INVENTION The invention will now be described in greater detail with reference to the following specific Examples. EXAMPLE I Synthesis of Peptide Compounds The new peptide compounds or peptide conjugates of the invention are synthesized by Fmoc-solid-phase synthesis on 2-chloro-tritylchloride resin (Int. J. Pept. Protein Res. 35, 1990, 161–214). According to this method Fmoc-protected amino acids are successively coupled, each time followed by cleavage of the protecting Fmoc-group in basic medium. Finally cleavage of the fully protected conjugates from the resin, oxidative cyclization to the cystine-containing cyclic peptide, and introduction of the DOTA-chelator, (e.g. as described by Heppeler et al. in Chem Eur. J. 1999; 5: 1974–1981), leads to the desired peptide compounds comprising the somatostatin analogues (1), (2) and (3), mentioned hereinbefore, as the somatostatin analogues carrying DOTA as the metal-chelating moiety, linked to the N-terminal free amino group of the peptide. EXAMPLE II Labeling of Peptide Compounds The above DOTA carrying peptide compounds (1) and (3) are labeled with 111 In by dissolving each compound in 0.01 M acetic acid, mixing this solution with 111 InCl 3 — solution (1 mCi/100 μl) in 0.05 M aqueous sodium acetate at higher temperature, and finally neutralizing the solution with HEPES buffer. Labeling with 90 Y, obtained from a 90 Sr— 90 Y radionuclide generator, is performed as follows. A solution of each of the above DOTA carrying peptide compounds (1) and (3) in 0.01 M acetic acid is treated with 90 Y (1.0 mCi/50 μl 0.5 M acetate solution). The mixture is left for approx. 1 hr at higher temperature to effect chelation. EXAMPLE III In Vitro Binding Experiments In vitro binding affinities are determined using transfected cell lines with somatostatin human receptor subtypes (hsst) 2, 3 and 5, as described by Reubi et al. in Eur. J. Nucl. Med. 27, 2000, 273–282. The affinity profiles (IC 50 values), determined for these somatostatin receptor subtypes, are presented in Tables I and II below. In these tables the results of labeled peptide compounds according to the invention, viz. 90 Y-labelled DOTA-(D)Phe-cyclo[Cys-(D)1-Nal-(D)Trp-Lys-Thr-Cys]-Thr-ol (Y-DOTA-[1-Nal 3 ]-OC; cpd. 8) and 90 Y-labelled DOTA-(D)Phe-cyclo[Cys-(D)3-benzothienylalanyl-(D)-Trp-Lys-Thr-Cys]-Thr-ol (Y-DOTA-[BzThi 3 ]-OC; cpd. 9), are compared with those of Y-DOTA-[2-Nal 3 ]-OC (cpd. 10) and Y-DOTA-[3-Pya 3 ]-OC (cpd. 11), referenced to the respective data of somatostatin 28 (cpd. 0) (Table II). Compounds 10 and 11 are prepared according to a method corresponding to the synthesis of compounds 8 and 9: see Examples I and II. For purpose of comparison, recently published results (Reubi et al.—see above) of an additional series of IC 50 values are also presented in Table I: OC to Y-DOTA-TOC (cpds. 4–7), also referred to the corresponding data of somatostatin S28 (SS-28; cpd. 0). TABLE I Cpd. No. Compound hsst 2 hsst 3 hsst 5 0 SS-28 2.7 ± 0.3 (19) 7.7 ± 0.9  (15) 4.0 ± 0.3 (19) 4 OC 2.0 ± 0.7 (5) 187 ± 55  (3) 22 ± 6   (5) 5 Y-DOTA-OC  20 ± 2   (5) 27 ± 8  (5) 57 ± 22  (4) 6 Y-DOTA-LAN  23 ± 5   (4) 290 ± 105 (4) 16 ± 3.4 (4) 7 Y-DOTA-TOC  11 ± 1.7 (6) 389 ± 135 (5) 114 ± 29  (5) Affinity profiles (IC 50 ) for human sst (hsst) 2, 3 and 5 receptors. All values are IC 50 ± SEM in nM. The number of experiments is given in parentheses. OC = Octreotide = H-(D)Phe 1 -cyclo[Cys 2 -Phe 3 -(D)Trp 4 -Lys 5 -Thr 6 -Cys 7 ]-Thr 8 -ol LAN = Lanreotide = H-(D)2-Nal-cyclo[Cys-Phe-(D)Trp-Lys-Val-Cys]-Thr-NH 2 TOC = H-(D)Phe-cyclo[Cys-Tyr-(D)Trp-Lys-Thr-Cys]-Thr-ol TABLE II Cpd. No. Compound hsst 2 hsst 3 hsst 5  0 SS-28 2.7 ± 0.3 (8) 3.7 ± 0.3 (8) 2.9 ± 0.4  (8)  8 Y-DOTA-[1-Nal 3 ]-OC 3.3 ± 0.2 (3) 26 ± 1.9 (3) 10 ± 1.6  (3)  9 Y-DOTA-[BzThi 3 ]-OC 3.4 13 4.1 10 Y-DOTA-[2-Nal 3 ]-OC 25 ± 1.0 (2) 133 ± 68  (2) 98 ± 12.5 (2) 11 Y-DOTA-[3-Pya 3 ]-OC 22 ± 9   (4) 205 ± 43  (4) 648 ± 165  (4) The above results show that the peptide compounds according to the present invention (cpds. 8 and 9) have a highly promising affinity profile with respect to somatostatin receptors. They are binding in the same range or even better to sst 5 as cpd. 6 and have significantly higher affinity than cpd. 5 for this receptor, even taken into account the different values for the SS-28 (cpd. 0) determined in separate laboratories (Table I and II). The affinity of cpd. 8 to sst 3 is in the same order of magnitude as for cpd. 5, but approx. five times better than for cpd. 6; compound 9 is even significantly better. Most surprising, however, is the affinity to the important receptor sst 2. Both compounds 8 and 9 have an approx. three times better binding affinity to sst 2 than even compound 7. From the above tables it will be clear, that compounds 10 and 11 have only moderate to low binding affinities to sst 2, 3 and 5. EXAMPLE IV Internalization Experiments The above favorable binding affinity has been confirmed in internalization experiments. Four 111 In-labelled compounds, viz. 111 In-labelled DOTA-[2-Nal 3 ]-OC, 111 In-labelled DOTA-TOC, 111 In-labelled DOTA-OC and an 111 In-labelled peptide compound of the invention, viz. 111 In-labelled DOTA-[1-Nal 3 ]-OC (DOTA-NOC), were tested in parallel in the same internalization assay. The experiments were carried out using 2.5 pmol 111 In-labelled peptide compound per 1 million AR42J cells. The internalization rate is clearly highest with the labeled peptide compound of the present invention, viz. 111 In-labelled DOTA-NOC: at 4 hours 26.6% injected dose (ID) per 1 million cells, compared with 12.0% ID/mio-cells for labeled DOTA-TOC, 8.0% ID/mio-cells for labeled DOTA-OC and only 0.6% ID/mio-cells for labeled DOTA-[2-Nal 3 ]-OC. EXAMPLE V Biodistributions In Vivo Biodistributions were carried out in tumor bearing Lewis rats. 111 In-labelled DOTA-NOC was used for these experiments and injected in Lewis rats bearing CA 20948 or AR42J tumors (see M. de Jong et al.: Eur. J. Nucl Med. 24, 1997, 368–371). In these biodistribution studies 111 In-labelled DOTA-NOC according to the present invention showed a significant higher tumor uptake and lower kidney uptake than 111 In-labelled DOTA-TOC, in comparison tests. EXAMPLE VI Binding Affinity The following example provides comparative data regarding peptides of the formula: (D)Phe 1 -cyclo[Cys 2 -A 3 -(D)Trp 4 -Lys 5 -Thr 6 -Cys 7 ]-A 8 wherein the amino acid at position A 8 is L-threonine and the amino acid at position A 3 is selected from the group consisting of 3-Iodo-Tyrosine (hereinafter 3-I-Tyr), 3-Benzothienlyalanine (hereinafter 3-BzThi) and 1-Napthylalanine (hereinafter 1-Nal). The latter three have the following structures: The evaluated peptides have the addition of the metal chelating ligand DOTA at the N-terminus and are chelated with stable or radioactive isotopes of Yttrium or Indium as indicated. Table III, presents the binding affinity of the new compounds to human somatostatin receptor subtypes as compared to the compound, Y-DOTA-TATE, described by Srinivasan et al. (U.S. Pat. No. 5,830,431). The data shows that both new peptide analogs with the amino acids 1-Nal, or 3-BzThi at the A 3 position have very high binding affinity to three subtype of the human somatostatin receptor, which is not observed with the previously described molecules, demonstrating that these compounds will be useful for imaging and therapy of human tumors that express one or more somatostatin receptor subtype especially those which do not express high levels of subtype 2. TABLE III In vitro Binding Affinity of Peptide Analogs to Human Somatostatin Receptor Subtypes IC 50 values Peptide (nM concentration) 2 No. Compound 1 hsst2 hsst3 hsst5 1 Y-DOTA-TATE 1.6 >1000 187 2 Y-DOTA-[3-I-Tyr 3 ]-TATE 1.2 170 65 3 In-DOTA-[1-Nal 3 ]-TATE 1.6 13 4.3 4 In-DOTA-[3-BzThi 3 ]-TATE 1.1 7 4 Derivatives of the claimed sequence: (D)Phe 1 -cyclo[Cys 2 -A 3 -Trp 4 -Lys 5 -Thr 6 -Cys 7 ]-Thr 8 Where peptide No. 1 is the comparison peptide with the natural amino acid, L-Tyrosine, at the A 3 position and peptides No. 2 through 4 are compounds of the invention. Peptides are DOTA-ligand linked at the N-terminal position and the DOTA ligand is complexed with stable isotopes of Y (Yttrium-89) or In (Indium-114), and A 3 is one of the amino acids listed in FIG. 1, and the C-terminal amino acid (A 8 ) is Threonine. IC 50 values were determined as described by Reubi et al. (Eur J Nuc Med 28:836–846, 2001). EXAMPLE VII Biodistribution Data Table IV and Table V present the biodistribution properties of Indium-111 radiolabeled versions of the new compounds in a rat tumor model, and show that the compounds have excellent biodistribution characteristics. Most notable are rapid blood clearance, high tumor uptake, predominately renal excretion, and low uptake in tissues which do not express somatostatin receptors. Somostatin receptors are present at high levels in tumor, pancreas and adrenals. TABLE IV Biodistribution of 111 In-DOTA-(1-Nal) 3 -TATE in AR42J Tumor Bearing Lewis Rats (Percent Injected Dose per Gram Tissue). Tissue 4 hr ± StdDev 24 hr ± StdDev 48 h ± StdDev Blood 0.04 ± 0.00 0.00 ± 0.00 0.00 ± 0.00 Tumor 4.01 ± 0.50 1.82 ± 0.26 1.11 ± 0.05 Kidneys 1.51 ± 0.09 0.75 ± 0.12 0.74 ± 0.08 Adrenals 10.76 ± 0.55  5.87 ± 1.40 5.22 ± 0.30 Pancreas 12.31 ± 0.88  2.45 ± 0.31 2.16 ± 0.24 Spleen 0.11 ± 0.01 0.04 ± 0.00 0.04 ± 0.01 Stomach 1.83 ± 0.62 0.92 ± 0.11 0.42 ± 0.33 Bowel 0.25 ± 0.07 0.17 ± 0.00 0.14 ± 0.01 Liver 0.09 ± 0.06 0.04 ± 0.01 0.06 ± 0.03 Lung 0.09 ± 0.01 0.03 ± 0.00 0.02 ± 0.01 Heart 0.02 ± 0.00 0.01 ± 0.00 0.01 ± 0.00 Bone 0.02 ± 0.00 0.01 ± 0.00 0.00 ± 0.00 TABLE V Biodistribution of 111 In-DOTA-(BzThi) 3 -TATE in AR42J Tumor Bearing Lewis Rats (Percent Injected Dose per Gram Tissue). Tissue 4 hr ± StdDev 24 hr ± StdDev 48 h ± StdDev Blood 0.02 ± 0.00 0.01 ± 0.00 0.01 ± 0.01 Tumor 4.12 ± 0.62 2.05 ± 0.75 1.10 ± 0.18 Kidneys 1.79 ± 0.15 1.83 ± 0.17 0.94 ± 0.30 Adrenals 5.71 ± 0.53 3.34 ± 0.72 2.84 ± 0.63 Pancreas 10.33 ± 0.34  3.30 ± 0.20 2.53 ± 0.57 Spleen 0.05 ± 0.01 0.05 ± 0.00 0.10 ± 0.11 Stomach 0.81 ± 0.23 0.66 ± 0.36 0.47 ± 0.07 Bowel 0.15 ± 0.02 0.13 ± 0.01 0.18 ± 0.02 Liver 0.10 ± 0.01 0.07 ± 0.01 0.10 ± 0.09 Lung 0.06 ± 0.00 0.05 ± 0.00 0.10 ± 0.13 Heart 0.01 ± 0.00 0.01 ± 0.00 0.01 ± 0.00 Bone 0.01 ± 0.01 0.01 ± 0.00 0.01 ± 0.00 EXAMPLE VIII Tissue Uptake Tumor and non-tumor tissue uptake is receptor specific (except for kidneys) as shown in the rat study presented in FIG. 1, which demonstrates that the observed uptake of 111 In-DOTA-[1-Nal 3 ]-TATE peptide in somatostatin receptor expressing tissues can be blocked by coinjection of non-radioactive, competitor, somatostatin analogs that have various receptor subtype specificity. As expected the efficacy of the unlabeled derivatives to compete with the uptake the radioactive compounds corresponds to expression level of somostatin receptors and specific subtypes. Having described the invention in detail, those skilled in the art will appreciate that modifications may be made of the invention without departing from its spirit and scope. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments described.

The invention relates to a peptide compound having an improved binding affinity to somatostatin receptors, comprising a somatostatin analogue as the peptide and a chelating group covalently linked to the N-terminal free amino group of said peptide, wherein said somatostatin analogue carries an 1-naphthylalanine or a 3-benzothienylalanine residue in its 3-position. The invention further relates to said peptide compound labeled with a detectable element or with a therapeutic radionuclide, as well as to a diagnostic method and to a method for the therapeutic treatment of tumors, by using the labeled compounds.

CLAIM OF PRIORITY This application claims the benefit of priority under 35 U.S.C. §119(e) of U.S. Provisional Application Ser. No. 61/341,806, filed on Apr. 5, 2010, which application is incorporated by reference herein, and is a Divisional Application of U.S. patent application Ser. No. 13/065,008, filed on Mar. 11, 2011, and which is incorporated by reference herein. FIELD The present disclosure relates generally to collectors for extreme ultraviolet (EUV) radiation, and in particular to EUV collector systems having enhanced EUV radiation collection capability. BACKGROUND ART EUV collector systems are used in EUV lithography systems to collect EUV radiation from an EUV radiation source and direct the EUV radiation to an aperture typically referred to as or associated with the intermediate focus. The radiation from the intermediate focus is then relayed by an illuminator to illuminate a reflective reticle. Radiation reflected from the illuminated reticle is then projected onto a wafer coated with a photosensitive material such as photoresist that records the reticle image. The wafer is then processed to form integrated microcircuits. FIG. 1 is a schematic diagram of a generalized configuration of a collector system 10 N that uses a normal-incidence collector (NIC) mirror MN. FIG. 2 is a schematic diagram of a generalized configuration of a collector system 10 G that uses a grazing-incident collector (GIC) mirror MG. Each collector system 10 N and 10 G has an EUV radiation source RS that emits EUV radiation 12 , a central axis A 1 , and an intermediate focus IF. Each collector system 10 N and 10 G is shown arranged adjacent an illuminator 20 that has an entrance aperture member 22 that defines an entrance aperture 24 . Entrance aperture member 22 is arranged at or near the intermediate focus IF. NIC mirror MN has a common input and output side 17 , while GIC mirror MG has an input end 16 and an output end 18 . In each collector system 10 N and 10 G, an important performance metric for EUV lithography is the amount and angular distribution of EUV radiation 12 the collector mirror MN or MG can deliver to the intermediate focus IF and through the entrance aperture 24 of illuminator 20 . As mentioned above, also of importance is the angular distribution of the EUV radiation 12 delivered through entrance aperture 24 of illuminator 20 . Entrance aperture 24 is used to define the limits of the intermediate focus IF so that illuminator 20 can have the proper field size and numerical aperture for illuminating the reticle (not shown). However, because neither type of collector system 10 N or 10 G can be made to perform perfectly, and because of magnification constraints on the system design, entrance aperture member 22 of illuminator 20 may also end up intercepting a substantial amount of EUV radiation 12 L, so that this intercepted EUV radiation 12 L is lost and is not utilized by the illuminator 20 , as illustrated in FIG. 3 . Also, due to design limitations or manufacturing imperfections in the collector system 10 N or 10 G, EUV radiation 12 passing through the entrance aperture 24 may not have the optimum angular distribution for use by the illuminator 20 . This lost or non-optimum EUV radiation 12 L is problematic because as much useable EUV radiation 12 as possible must be provided to illuminator 20 so that there is sufficient radiation to uniformly illuminate the reticle and adequately expose the photosensitive material (photoresist) on the wafer. SUMMARY The present disclosure is directed to EUV collector systems having enhanced EUV radiation collection capability. The enhanced EUV radiation collection capability is provided by a radiation-collection enhancement device (RCED) that is arranged at or adjacent an illuminator entrance aperture member that defines an entrance aperture. One RCED on either side of the illuminator entrance pupil (aperture) can be used, or two RCEDs on either side of the illuminator entrance pupil (aperture) can be used. The RCED can be configured so that EUV radiation that would otherwise not pass through the entrance aperture is redirected through the entrance aperture. In addition, by selectively configuring the inner surface of the RCED, a desired angular distribution (e.g., one that is more compatible with illumination system requirements) of the EUV radiation passing through the entrance aperture can be obtained. The RCED need not be circularly symmetric and can have one or more different types of inner surfaces (e.g., polished, planar, rough, undulating, etc.) that can grazingly reflect or otherwise re-direct incident EUV radiation. Some of this redirected EUV radiation can be used to illuminate discrete detectors that may be, for example, part of an EUV lithography alignment system. A roughened inner surface, for example, may be employed in certain applications, and on some or all of the at least one inner surface, where it is advantageous to scatter the otherwise less useful EUV radiation through the entrance aperture of the illuminator, for example to homogenize the radiation distribution in the far field. The one or more inner surfaces are thus referred to herein below also as “redirecting surfaces.” Some embodiments of the RCED include multiple inner surfaces, such as defined by concentric mirror shells. The RCED can be attached to the entrance aperture of the illuminator or can be spaced apart therefrom. The RCED can be configured (or be exchanged out for another RCED at a semiconductor manufacturing facility) to accommodate changes in the requirements on the EUV radiation being delivered to the illuminator. The RCED can be used to reduce the collection specifications on the collector mirror, making it easier to build and/or lower the cost of the collector system. The RCED is particularly useful in mitigating adverse affects due to collector system misalignments and perturbations. The RCED can be configured so that the captured light that would otherwise be lost or be less useful because of improper angular distribution can be redirected to the illuminator while still preserving (or at least substantially preserving) the etendue of the collector-illuminator system. An example RCED uses grazing-incident reflection to direct otherwise lost or less useful radiation through the entrance aperture of the illuminator. The redirecting surface of RCED can be highly polished and have a coating that maximizes the critical angle for grazing-incident reflection and enhances the collection solid angle. The coating may comprise a single layer or multilayer. Example coating materials include Ruthenium for a single-layer coating and Mo/Si for multilayer coatings. Thus, an aspect of the disclosure is a collector system for collecting and directing EUV radiation from an EUV radiation source through an aperture of an aperture member. The collector system includes a collector mirror configured to collect and direct the EUV radiation toward the aperture. The collector system also includes a radiation-collection enhancement device arranged at or adjacent the aperture and configured to collect a portion of the EUV radiation that would not otherwise pass through the aperture or would pass through the aperture at less than optimum angular distribution and redirect said portion of the EUV radiation through the aperture and with an angular distribution better suited for use by the illuminator. Another aspect of the disclosure is a method of collecting EUV radiation from an EUV radiation source and directing the EUV radiation through an aperture. The method includes collecting the EUV radiation from the radiation source and directing the EUV radiation to the aperture. The method also includes collecting a portion of the directed EUV radiation that would not otherwise pass through the aperture with at least one redirecting surface arranged adjacent the aperture, and redirecting said portion of EUV radiation through the aperture. Another aspect of the disclosure is a method of collecting EUV radiation in EUV lithography system having an aperture member with an aperture. The method includes generating the EUV radiation with an EUV radiation source. The method also includes collecting the EUV radiation from the EUV radiation source with an EUV collector and directing the EUV radiation to the aperture. A first portion of the directed EUV radiation is directed to pass through the aperture and a second portion of EUV radiation is directed to be intercepted by the aperture member. The method further includes collecting the second portion of EUV radiation with at least one first redirecting surface arranged adjacent the aperture, and redirecting the portion of EUV radiation through the aperture so that both the first and second portions of the directed EUV radiation pass through the aperture. Additional features and advantages of the disclosure are set forth in the detailed description below, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the disclosure as described herein, including the detailed description which follows, the claims, as well as the appended drawings. The claims set forth hereinbelow constitute part of this specification and are incorporated herein directly and by reference. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a generalized prior art NIC collector system, illustrating how some of the focused EUV radiation does not make it through the -entrance aperture; FIG. 2 is a schematic diagram of a generalized prior art GIC collector system, illustrating how some of the focused EUV radiation does not make it through the entrance aperture member; FIG. 3 is a close-up cross-sectional view of the entrance aperture, illustrating how a portion of the EUV radiation generally directed to the intermediate focus is blocked by the entrance aperture member; FIG. 4 is a close-up cross-sectional view similar to FIG. 3 , but that includes an example RCED and that shows how the RCED redirects EUV radiation that would otherwise be lost to pass through the entrance aperture; FIG. 5A is a cross-section view of an example multi-shell RCED; FIG. 5B is a face-on view of the multi-shell RCED of FIG. 5A showing the spokes of a support structure (“spider”) for the two reflective shells; FIG. 6 is a schematic cross-sectional view of an example RCED that is spaced apart from the entrance aperture member and that is attached thereto via a support structure; FIG. 7 is a generalized NIC collector system similar to that of FIG. 1 , but with a RCED; FIG. 8 is a more detailed schematic diagram of an example EUV NIC collector system and that includes a RCED and a LPP EUV source; FIG. 9 is a generalized GIC collector system similar to that of FIG. 2 , but with a RCED; FIG. 10 is a more detailed schematic diagram of an example EUV GIC collector system and that includes a RCED and a LPP EUV source; FIG. 11 is an isometric view of an example conic RCED having circular symmetry and linear walls; FIG. 12 is a side cross-sectional view of an example conic RCED having circular symmetry and curved walls; FIG. 13 is a cross-section view of an example RCED, where the inner wall includes a plurality of facets and has non-circular symmetry; FIG. 14 is a cross-sectional view of an example RCED, where the inner wall includes a variety of different configurations such as planar, roughened, undulating and curved polished; FIG. 15 is a lateral cross-sectional view of an example RCED where the inner surface includes an undulating surface; FIG. 16 is similar to FIG. 12 but includes a roughened inner surface portion adjacent the output end; FIG. 17 is a schematic diagram similar to FIG. 2 and shows an example GIC collector system 10 G with illuminator 20 , illustrating the etendue limitations associated with transferring the EUV radiation from the radiation source to the illuminator; FIG. 18A is similar to FIG. 4 and illustrates an example embodiment where the RCED includes front and rear tapered bodies (sections) on either side of the aperture member; FIG. 18B is similar to FIG. 18A , except that the tapered bodies are separated from the aperture member; FIG. 19 is similar to FIG. 5A and illustrates an example RCED that includes multiple inner surfaces on either side of the aperture member; FIG. 20 is similar to FIG. 6 and illustrates another example RCED that includes a single front mirror shell and a single rear mirror shell as stood off from aperture member by respective stand-off support structures; FIG. 21 is similar to FIG. 16 and illustrates another example RCED having front and rear tapered bodies on either side of the aperture member; FIG. 22 is similar to FIG. 21 except that the RCED includes cooling channels on its outer surface; FIG. 23 is a schematic diagram of an EUV lithography system that uses an EUV collector system that employs the RCED of the present disclosure. The various elements depicted in the drawing are merely representational and are not necessarily drawn to scale. Certain sections thereof may be exaggerated, while others may be minimized. The drawing is intended to illustrate an example embodiment of the disclosure that can be understood and appropriately carried out by those of ordinary skill in the art. In the discussion below, the term “far field” is generally understood as being a substantial distance beyond the intermediate focus IF, e.g., 1 meter or greater. DETAILED DESCRIPTION FIG. 4 is a close-up, cross-sectional view of an entrance aperture member 22 of illuminator 20 similar to FIG. 3 , but showing an example RCED 100 arranged along central axis A 1 and adjacent entrance aperture member 22 on the side closest to EUV radiation source RS (not show in FIG. 4 ; see e.g., FIGS. 1 and 2 ). RCED 100 has a body portion 110 that includes a central aperture 114 that, along with body portion 110 , defines a tapered inner surface 120 that goes from wider at an input end 122 to narrower at an output end 124 , i.e., the taper generally narrows in the +Z direction. Inner surface 120 is designed to redirect at least a portion of EUV radiation 12 L so that this EUV radiation 12 L, which would otherwise not pass through entrance aperture 24 or that would pass through the entrance aperture 24 but with a less than optimum angle for use by the illuminator 20 , passes through entrance aperture 24 . In an example embodiment, inner surface 120 is smooth and covered with a coating 121 (single-layer or multi-layer, as described below) designed to enhance the reflectivity of the inner surface 120 at EUV wavelengths and the grazing incidence angles of EUV radiation 12 L. Various forms for RCED 100 are discussed in greater detail below. In an example embodiment, RCED 100 is or includes a grazing-incidence mirror element. EUV wavelengths typically range from 10 nm to 15 nm, with an exemplary EUV wavelength being 13.5 nm. In an example embodiment, inner surface 120 of RCED 100 is configured to match the numerical aperture (NA) requirements of illuminator 20 . In another example, RCED 100 can be adjusted or swapped out for a different RCED to accommodate changes (e.g., NA changes) in illuminator 20 . Generally, RCED 100 can be configured to match or otherwise accommodate particular angular distribution requirements of illuminator 20 . An aspect of the disclosure includes using RCED 100 to reduce the focusing requirements on the collector mirror (MN or MG) to allow the design of an illuminator 20 having a smaller entrance aperture 24 than could reasonably be accommodated by using a collector mirror (MN or MG) alone. This aspect of the disclosure can serve to simplify the collector requirements and/or illuminator design, which in turn reduces the collector and/or illuminator cost. In an example, RCED 100 is disposed adjacent entrance aperture member 22 of illuminator 20 , and can be attached to the entrance aperture member 22 or spaced apart therefrom. Attachment of RCED 100 to entrance aperture member 22 can be accomplished mechanically or magnetically so that the RCED 100 and the entrance aperture member 22 appear integrally formed, as shown in FIG. 4 . A spaced-apart RCED 100 (discussed below in connection with FIG. 6 ) may be preferred in some instances to achieve specific performance goals, or for ease of manufacture and assembly. In such case, a stand-off mechanism may be configured to achieve a precise separation distance. FIG. 5A is a cross-sectional view that illustrates an example RCED 100 that includes multiple inner surfaces 120 , such as formed by concentrically arranged mirror shells 103 - 1 and 103 - 2 . The concentric mirror shells 103 - 1 and 103 - 2 define two RCED apertures 114 - 1 and 114 - 2 . FIG. 5B is a face-on view of RCED 100 of FIG. 5A showing spokes 105 of a support structure (“spider”) that maintain the two mirror shells 103 - 1 and 103 - 2 in a spaced-apart and aligned configuration. Thus, RCED 100 generally includes at least one inner surface 120 , and in certain embodiments includes multiple inner surfaces 120 . FIG. 6 is a schematic cross-sectional view of an example RCED 100 that is spaced apart from entrance aperture member 22 of illuminator 20 , and that is attached thereto via a stand-off support structure 113 . In FIG. 5A and in FIG. 6 , the intermediate focus IF is shown as located in the plane PL defined by entrance aperture member 22 of illuminator 20 . The intermediate focus IF represents the central location of the focused EUV radiation distribution formed by the GIC collector system 10 G. It is noted here that while RCED 100 redirects at least a portion of EUV radiation 12 L that otherwise would not make it through entrance aperture 24 of illuminator 20 , in some embodiments RCED 100 is configured to also redirect through the entrance aperture 24 at least some EUV radiation 12 that would in fact have made it through the entrance aperture 24 had it not been redirected (see, e.g., one of the scattered EUV radiation 12 in FIG. 16 ). In such an embodiment, the redirection of EUV radiation 12 that would have made it through the entrance aperture 24 anyway will typically be done to change the angular distribution of the EUV radiation 12 passing through entrance aperture 24 and thereby make such EUV radiation 12 better suited to meet the angular input requirements of the illuminator 20 . In an example, the redirection of EUV radiation 12 is optimized to the angular distribution requirements of illuminator 20 . The output end 124 of RCED 100 can be smaller than entrance aperture 24 and still provide improved light collection. Experiments have shown that an RCED 100 with an output end 124 having a diameter of 4 mm passes substantially the same amount of EUV radiation 12 as a 6 mm entrance aperture 24 but resulted in a better angular distribution of the EUV radiation 12 in the far field. NIC Collector with RCED FIG. 7 shows a generalized NIC collector system 150 similar to NIC collector system 10 N of FIG. 1 , but with a RCED 100 arranged adjacent entrance aperture member 22 of illuminator 20 . FIG. 8 is a more detailed schematic diagram of an example NIC collector system 150 based on the generalized NIC collector system 10 N of FIG. 7 . FIG. 7 and FIG. 8 show the illuminator 20 acceptance angle θ that applies generally for both types of collector systems. The numerical aperture NA of illuminator 20 is given by NA=n·sin θ, where n is the refractive index of the medium, which is presumed to be a vacuum for an EUV lithography system (i.e., n=1). With reference to FIG. 8 , NIC collector system 150 includes a high-power laser source LS that generates a high-power, high-repetition-rate laser beam 11 having a focus F 11 . NIC collector system 150 also includes along a central axis A 1 a fold mirror FM and a large (e.g., ˜600 mm diameter) ellipsoidal NIC mirror MN that includes a surface S 1 with a multilayer coating 154 . The multilayer coating 154 provides good reflectivity at EUV wavelengths. NIC collector system 150 also includes a Sn source 160 that emits a stream of Sn pellets (or droplets) 162 that pass through and are irradiated by laser beam focus F 11 . In the operation of NIC collector system 150 , laser beam 11 from laser source LS irradiates Sn pellets (or droplets) 162 as the pellets (or droplets) pass through the laser beam focus F 11 , thereby produce a high-power laser-produced plasma source LPP-RS. Laser-produced plasma source LPP-RS typically resides on the order of a few hundred millimeters from NIC mirror MN and emits EUV radiation 12 , as well as energetic Sn ions, particles, neutral atoms, and visible, UV and infrared (IR) radiation. The portion of the EUV radiation 12 directed toward NIC mirror MN is collected by the NIC mirror MN and directed (focused) toward entrance aperture 24 to intermediate focus IF to form intermediate radiation distribution RD. As discussed above, some of the EUV radiation 12 (identified as 12 L) has a trajectory that would be blocked by entrance aperture member 22 . However, at least a portion of EUV radiation 12 L is collected by RCED 100 and redirected through entrance aperture 24 of illuminator 20 . This provides more EUV radiation 12 for forming a far-field radiation distribution RD, and thus more radiation for ultimately forming an image of the reticle at the wafer in an EUV lithography system. It is noted here that the EUV radiation directed toward entrance aperture 24 by the EUV collector system is not tightly focused precisely at intermediate focus IF and does not generally form a perfectly uniform far-field radiation distribution RD. Rather, the radiation distribution RD formed by the collector system at the intermediate focus IF is somewhat ill-defined due to imperfections (aberrations) in the particular collector system used, as well as scattering effects in the collector system. Further, illuminator 20 is typically designed so that it does not require as an input a sharply focused spot or a crisply defined disk. FIG. 12 , introduced and discussed below, shows an intermediate focus region IFR and that schematically illustrates a more realistic extent of the intermediate focus IF as caused by aberrations and scattering, and that is representative of the extent of an actual EUV radiation distribution. Illuminator 20 typically is configured to receive EUV radiation that passes through entrance aperture 24 with a specified angular distribution and uniformity. The illuminator 20 serves to condense and uniformize this EUV radiation for uniformly illuminating the reflective reticle (usually to within a few percent (e.g., between 2% and 5% uniformity). Thus, RCED 100 may be designed to capture additional misdirected EUV radiation from the collector mirror and redirect it to meet the illuminator specifications, thereby enhancing illuminator performance, and in particular increasing the amount of EUV radiation that can be effectively used to illuminate the reticle in an EUV lithography system. In an example embodiment, the NIC mirror MN or GIC mirror MG is formed with looser (reduced) tolerances than would otherwise be possible, and RCED 100 is used to compensate for the reduced tolerances, errors, misalignments, thermal distortions, etc. The combination of the collector mirror and RCED 100 can thus be used to meet the system tolerance at the intermediate focus plane PL for the radiation distribution RD. This approach makes it easier and likely less expensive to form the NIC or GIC mirror when such mirror is used in combination with a RCED 100 . GIC Collector with RCED FIG. 9 shows a generalized GIC collector system 180 similar to GIC collector system 10 G of FIG. 2 , but with a RCED 100 arranged adjacent entrance aperture member 22 . FIG. 10 is a more detailed schematic diagram of an example GIC collector system 180 based on the generalized GIC collector of FIG. 9 . GIC collector system 180 includes a laser source LS that generates a laser beam 11 . GIC mirror MG is shown as having GIC shells M 1 and M 2 arranged along central axis A 1 . In practice, one or more GIC shells can be used. A lens L and a fold mirror FM serve to direct laser beam 11 along central axis A 1 and through the GIC mirror MG in the −Z direction to a focus Fll on the opposite side of GIC mirror MG from laser source LS. In an example embodiment, GIC shells M 1 and M 2 include Ru coatings, which are relatively stable and can tolerate a certain amount of Sn coating. Note that fold mirror FM and laser beam 11 from laser source LS are shown located between GIC mirrors MG and the intermediate focus IF. An alternative arrangement places laser source LS and fold mirror FM between the input end 16 of GIC mirror MG and the laser beam focus F 11 . A high-mass, solid, moving Sn target 182 having a surface 184 is arranged along central axis A 1 so that a portion of the surface 184 of Sn target 182 is at focus F 11 . A target driver 186 (e.g., a motor) is shown for moving Sn target 182 by way of example. The laser beam- 11 incident upon surface 184 of Sn target 182 forms laser-produced plasma source LPP-RS. Moving Sn target 182 at high speed allows for laser beam 11 to be incident upon surface 184 of Sn target 182 at a different location for each laser pulse. The emitted EUV radiation 12 from laser-produced plasma source LPP-RS formed on Sn target 182 is generally in the +Z direction and travels through GIC mirror MG in the opposite direction of laser beam 11 , i.e., in the +Z direction. Some of EUV radiation 12 passes directly through RCED 100 and to intermediate focus plane PL to form radiation distribution RD, while other EUV radiation 12 L is collected by RCED 100 and directed through entrance aperture 24 by grazing-incidence reflection from reflective inner surface 120 . As with the NIC collector system 150 , this configuration provides more useful radiation (e.g. an angular distribution the better meets the illuminator specifications) passing through the intermediate focus aperture radiation for forming radiation distribution RD and thus more radiation for ultimately forming an image of the reticle at the wafer in an EUV lithography system. While the example EUV radiation source has been described above as an LPP EUV radiation source, a discharge-produced plasma (DPP) EUV radiation source can also be used in connection with the embodiments of the present disclosure. Example RCEDs RCED 100 can have a wide range of configurations that have a generally tapered shape in the +Z direction when placed in front of (i.e. on the collector side of) the entrance aperture member 22 , and a generally shape in the -Z direction when placed behind (i.e. on the illuminator side of) the entrance aperture member 22 . If the RCED 100 is intended to homogenize and otherwise improve the angular distribution of EUV radiation in the far field behind entrance aperture member 22 of illuminator 20 , then it can have a fairly complex inner surface configuration. For example, the inner surface configuration can include a precisely contoured reflecting surface or an undulating surface or even a roughened inner surface configured to uniformize and otherwise optimize the EUV radiation coming from, for example, distributed shells of a multi-shell GIC mirror MG. On the other hand, if RCED 100 is intended to distribute EUV radiation to larger angles behind entrance aperture member 22 to optionally illuminate an alignment structure beyond the field of the illuminator 20 , then the inner surface 120 of RCED 100 can be preferably configured to maximize the angles passing through entrance aperture 24 of illuminator 20 . Or, if RCED 100 is only intended to maximize the amount of EUV radiation 12 through the entrance aperture 24 of illuminator 20 , then inner surface 120 can be designed to have one or more surface configurations that achieve this goal. FIG. 11 is an isometric view of an example RCED 100 that illustrates an example conic RCED 100 that has a reflective inner surface 120 with a linear taper. RCED 100 has a central axis AC. A coating 121 is shown on inner surface 120 . The linear taper can be configured to correspond (e.g., match) the NA or the angular distribution of illuminator 20 . A simple version of RCED 100 includes a polished inner surface 120 that, along with coating 121 , grazingly reflects EUV radiation 12 L. FIG. 12 is a longitudinal cross-sectional view of an example RCED 100 that illustrates an example where the RCED 100 that has a reflective inner surface 120 with a curved (i.e., flared) taper. As discussed above, the curved taper can be configured to correspond (e.g., match) the NA or the required angular distribution of illuminator 20 . FIG. 13 is lateral cross-sectional view of an example RCED 100 that has an inner surface 120 that is not rotationally symmetric and that has a plurality of (e.g., eight) inner surfaces 120 F- 1 through 120 F- 8 . The faceted inner surface 120 F can be, for example, linearly tapered or curved tapered. FIG. 14 is similar to FIG. 13 , and shows an example RCED 100 having a variety of inner surfaces 120 , such as one or more inner surface 120 F, an undulating or grooved inner surface 120 G, a roughened inner surface 120 R and a polished, curved inner surface 120 P. Such a multi-form inner surface 120 may be employed for specialized applications. FIG. 15 is a lateral cross-sectional view of an example RCED 100 where inner surface 120 includes an undulating or grooved inner surface 120 G. Such an inner surface 120 G can serve to smooth out or otherwise optimize the far-field EUV radiation distribution RD without using scattering from a high-spatial-frequency roughened surface. FIG. 16 is similar to FIG. 12 , but includes a portion of roughened inner surface 120 R adjacent output end 124 . The portion of Roughened surface 120 R serves to provide wider scattering angles for EUV radiation 12 L than a polished inner surface 120 (e.g., 120 P; see FIG. 14 ), and serves to uniformize or otherwise improve (or optimize) the EUV radiation distribution RD at entrance aperture 24 of illuminator 20 . Body portion 110 of RCED 100 may be formed from a metal, a ceramic, a plastic or a glass or glass-like material. In an example, body portion 110 (including inner surface 120 ) of RCED 100 is smooth and has a controlled high-spatial-frequency roughness (as understood in the art of EUV mirrors) to control scattering. However, example embodiments include cases where inner surface 120 (and optional coating 121 ) are configured with a surface roughness configured to generate a select scattering (e.g., a broad scattering) of EUV radiation collected by the RCED 100 , as discussed above in connection with FIG. 16 . If body portion 110 of RCED 100 is made of a plastic or other material that can be cast, then it can indeed be made very inexpensively and with a high degree of surface smoothness limited only by the smoothness of the master cast. Such a plastic or other non-metal RCED substrate can be coated with a high-atomic-number material (e.g., Ruthenium) to improve or optimize the grazing incidence reflection from the inner surface 120 of RCED 100 . If RCED 100 is to be subjected to a significant thermal load, then a preferred body material may be a metal. In an example embodiment, a metal body portion 110 of RCED 100 has an inner surface 120 that is polished to a desired smoothness, or is electroformed. Example metals for body portion 110 of RCED 100 include stainless steel, nickel, copper, aluminum, and like metals that can be highly polished. Another example material for body portion 110 of RCED 100 is a thermally resistant material such as ZERODUR. In an example embodiment, body portion 110 of RCED 100 is configured to support a cooling mechanism, such as cooling channels 129 (see FIG. 4 ). As discussed above, inner surface 120 may include a reflective coating 121 tailored to optimize the reflectivity of EUV radiation 12 at grazing incidence. While Ru is a preferred coating material, other high-atomic-number materials—such as Cu, Au, Pd, Sn, Pt, and Au—can also be used, as long as the specific application would not prohibit the use of such a coating. In addition, a resonant multilayer coating 121 can be used. Such a coating 121 would serve to broaden the acceptance angle and can increase the efficiency of RCED 100 . An example multilayer coating 121 includes layers of Mo and Si. RCED with Front and Rear Sections The amount of EUV radiation 12 that can be transferred from radiation source RS through GIC mirror MG and to illuminator 20 is limited by the overall system etendue , and in particular the design input etendue of the illumination system. However, in the case of a grazing incidence collector it is worth noting that the etendue of the individual GIC shells (M 1 , M 2 , etc.) will typically be considerably smaller than that of the illuminator 20 , and that the far-field EUV radiation distribution RD from the GIC will have gaps due to the nature of the separated shells. Thus, much of the EUV radiation 12 P (Refer to FIG. 17 ) that would be lost can be recovered by RCED 100 without violating the etendue principle, and in particular without exceeding the etendue of the illuminator 20 . Indeed, the RCED 100 can be used to redistribute the angular distribution of the far field radiation to better match the input angular distribution specifications of the illuminator 20 without violating the optical invariant (i.e., the etendue principle). As discussed above, much of the recovered EUV radiations 12 P gets directed into dark spaces on either side of the unaided far-field images formed by the GIC mirrors MG. This serves to homogenize and further optimize the far-field radiation distribution RD. FIG. 17 is a schematic diagram similar to FIG. 2 and shows an example GIC collector system 10 G with illuminator 20 . Illuminator 20 and entrance aperture member 22 define input and output acceptance angle limits 19 -I and 19 -O on the input and output sides of the entrance aperture 24 . Even for the EUV radiation 12 that passes through entrance aperture member 22 , some of this EUV radiation 12 P has an angle relative to central axis A 1 that precludes this radiation from entering and being processed by illuminator 20 . This is because the image formation process associated with GIC collector system 10 G is imperfect and is generally directed to trying to get as much EUV radiation 12 as possible from radiation source RS to illuminator 20 . With reference to FIG. 18A , in an example embodiment RCED 100 includes front and rear sections 110 F and 110 R on either side of entrance aperture member 22 . FIG. 18B is similar to FIG. 18A , except that the front and rear sections 110 F and 110 R are separated from entrance aperture member 22 . FIGS. 18A and 18B illustrate EUV radiation 12 that passes through RCED 100 with no bounces ( 12 ), one bounce ( 12 L) and two bounces ( 12 P). Note that the front and rear sections 110 F and 110 R can also be considered separate RCEDs with possibly different curvatures or patterning on the front RCED versus the rear RCED. Accordingly, so the description of these sections 110 F and 110 R as being part of one RCED 100 or as being two different RCEDs is the same, and in some instances herein, front and rear RCED sections are referred to simply as front and rear RCEDs. In an example, front and rear sections 110 F and 110 R are axially tapered in opposite directions, as shown. FIG. 19 is similar to FIG. 5A and illustrates an example RCED 100 that includes multiple inner surfaces 120 on either side of entrance aperture member 22 , such as formed by two sets of concentrically arranged mirror shells, namely front mirror shells 103 F- 1 and 103 F- 2 , and rear mirror shells 103 R- 1 and 103 R- 2 . Each of the mirror shells 103 F- 1 , 103 F- 2 , 103 R- 1 and 103 R- 2 can be considered sections of RCED 100 or even a separate RCED 100 . Once again, it is noted that front section 110 F may have one or more surfaces whereas rear section 110 R may have a number of surfaces different from the front section 110 F. Similarly, front section 110 F may be separated from the entrance aperture member 22 while rear section 110 R may be attached to or separated from the entrance aperture member 22 , or vice versa. FIG. 20 is similar to FIG. 6 and illustrates another example RCED 100 that includes a single front mirror shell 103 F and a single rear mirror shell 103 R as stood off from entrance aperture member 22 by respective stand-off support structures 113 F and 113 R. Front and rear mirror shells 103 F and 103 R can also be considered as separate RCED sections or as separate RCEDs with different curvatures, different stand-offs, and a different number of surfaces between the front and rear RCEDs, etc. FIG. 21 is similar to FIG. 16 and illustrates another example RCED 100 having front and rear sections 110 F and 110 R on either side of entrance aperture member 22 . Front and rear sections 110 F and 110 R have respective axial lengths LF and LR, and in an example have an axial taper, as shown. FIG. 22 is the same as FIG. 21 and includes cooling channels 129 arranged on each of the sections 110 F and 110 R to cool these sections by flowing a cooling fluid through the cooling channels 129 . In an example, one of the cooling channels 129 runs around the input end 122 . As discussed above, front and rear sections 110 F and 110 R can also be considered as separate RCED sections or as separate RCEDs with different curvatures, different cooling configurations, different stand-offs, and different number of surfaces between the front and rear RCEDs, etc. A desirable feature in a collector system is the ability to filter out unwanted broadband infrared radiation 240 generated by the EUV radiation source RS. Thus, with reference again to FIG. 22 , an IR filter 250 is disposed adjacent input end 122 or output end 124 of front section 110 F. Other locations for IR filter 250 are also possible. IR filter 250 is configured to filter out broadband infrared radiation 240 that may also be collected and reflected by the grazing incidence or normal incidence collector and delivered to entrance aperture member 22 . In an example embodiment, IR filter 250 comprises a low-density, free-standing grating having crossed-grating lines 252 (see insets, FIG. 22 ) and a support frame 254 . The crossed-grating lines 252 have a period smaller than the wavelength of infrared radiation 240 . If the areal density of crossed-grating lines 252 is relatively low (e.g. only 3% areal density coverage with metal crossed-grating lines 252 ) then the filtration of the infrared radiation 240 can be high while letting most (e.g. ˜97%) of the EUV radiation pass through. Where IR filter 250 has metal crossed-grating lines 252 , it can be thermally attached to the cooled RCED 100 to carry away any thermal load to which it may be subjected. Thus, an aspect of the methods disclosed herein includes filtering infrared radiation 240 from the EUV radiation source RS immediately upstream or downstream of the at least one redirecting surface associated with RCED 100 . An example method of making a suitable crossed-grating-based IR filter 250 is now described. To filter infrared radiation 240 while transmitting EUV radiation, the grating period needs to be less than the IR radiation wavelength. Also, since a substrate will generally absorb EUV radiation, it is preferred that the grating be freestanding, or alternatively, the supporting substrate be very thin (i.e., membranous) and be made of a material that has low absorption at 13.5 nm. For example, a half-micron thick Si membrane would reduce the EUV transmission at 13.5 nm by about a factor of 2×. If a 0.1 micron thick Si membrane were used, it would have a transmission at 13.5 nm of about 87%, which might be deemed acceptable. For a linear grating in the vertical (Y) direction, polarization components of the infrared radiation 240 in the Y direction would get reflected, with some absorption in the metal of the grating depending on its conductivity. To reflect all polarization components, a crossed-grating is employed, i.e., grating lines running in both the X and Y directions. All wavelengths below the period of the grating would pass thru the grating spaces. Any EUV radiation that hits the grating lines will get absorbed, while that which passes through the spaces is transmitted. If the grating lines represent only 5% of the grating area, then 5% of the EUV radiation will be absorbed, 95% will be transmitted, and substantially no infrared radiation at wavelengths longer than the grating period will be transmitted. To produce a master pattern of grating lines with the appropriate period and the appropriate linewidths, a suitable substrate is selected. An example substrate is a silicon wafer or thin glass. The wafer is coated with a thin chrome layer (e.g., less than 0.1 micron thick) as an adhering layer. The thin chrome layer is then coated with a thin (e.g., about 0.1 micron) plate-able metal layer, such as gold or other suitable metal. The metal layer is then coated with photoresist of a desired thickness. A master grid pattern with the appropriate period is lithographically formed in the photoresist layer. Developing the photoresist provides the negative of the grating pattern in the photoresist atop the plate-able metal layer. The photoresist layer is then plated with the same plate-able metal as the underlying plate-able metal layer. The photoresist is then washed away, e.g., using acetone. The resulting structure is now a thick metal grating atop of the approximately 0.2 micron thick chrome and plate-able metal layers supported by the substrate. A support structure can be attached to the outside of the metal grating structure so that the metal structure can be free-standing inside of the support structure. An example support structure is a washer that is epoxied to the metal grating structure. The grating structure periphery can be made to be thick and free of grating lines. At this point, chrome and plate-able metal layers are removed, e.g., using a liquid or beam etch process. Next, the substrate is removed, e.g., by a liquid etch suitable for the particular substrate (e.g., HF for a glass substrate). The result is a free-standing, metal crossed grating supported around its outer edge so that it can be handled and also mounted into position relative to the RCED 100 . EUV Lithography System with EUV Collector and RCED FIG. 23 is an example EUV lithography system (“lithography system”) 300 according to the present disclosure. Example lithography systems are disclosed, for example, in U.S. Patent Applications No. U.S. 2004/0265712A1, U.S. 2005/0016679A1 and U.S. 2005/0155624A1, which are incorporated herein by reference. Lithography system 300 includes a system axis AS and an EUV radiation source RS that emits working EUV radiation 12 nominally at λ=13.5 nm. Lithography system 300 also includes along system axis AS an EUV collector mirror (NIC or GIC) 310 and a RCED 100 as described above. EUV collector mirror 310 and RCED 100 comprise a collector system 312 . Collector system 312 also optionally includes EUV radiation source RS. EUV radiation source RS may include, for example, a LPP EUV radiation source or a DPP EUV radiation source. An illuminator 20 with an input end 20 A and an output end 20 B is arranged along system axis AS and adjacent and downstream of collector system 312 . Illuminator 20 includes entrance aperture member 22 with entrance aperture 24 . EUV collector mirror 310 (shown configured as a GIC mirror for illustration) collects EUV radiation 12 from EUV radiation source RS located at source focus SF. The collected EUV radiation 12 is directed to entrance aperture 24 , with the intention of forming a radiation distribution RD at intermediate focus IF. RCED 100 operates as described above to enhance the EUV radiation 12 focusing process by redirecting at least a portion of EUV radiation 12 L that would otherwise not pass through entrance aperture 24 to the illuminator 20 , to pass through entrance aperture 24 . Thus, illuminator 20 receives at input end 20 A EUV radiation 12 at the intermediate focus plane PL from radiation distribution RD and outputs at output end 20 B a more uniform EUV radiation 12 ′ (i.e., condensed EUV radiation) to a reflective reticle 336 . Where lithography system 300 is a scanning type system, EUV radiation 12 ′ is typically formed as a substantially uniform line of EUV radiation at reflective reticle 336 that scans over the reflective reticle 336 . It is also noted that illuminator 20 may image a portion of the EUV radiation passing through entrance aperture 24 to a region outside of the reticle patterned area (e.g., in a kerf), and that this EUV radiation (denoted 12 ′A in FIG. 23 ) can be used for alignment purposes, e.g., by being incident upon reticle alignment marks that reside outside of the patterned area used for forming microcircuit features. In an example embodiment, EUV radiation 12 ′A is detected by a photodetector 360 , which forms electronic signals S 360 that can be processed (e.g., in a computer, not shown) to perform alignment. A projection optical system 326 is arranged along (folded) system axis AS downstream of illuminator 20 and reflective reticle 336 . Projection optical system 326 has an input end 327 facing output end 20 B of illuminator 20 , and an opposite output end 328 . Reflective reticle 336 is arranged adjacent the input end 327 of projection optical system 326 and a semiconductor wafer 340 is arranged adjacent output end 328 of projection optical system 326 . Reflective reticle 336 includes a pattern (not shown) to be transferred to semiconductor wafer 340 , which includes a photosensitive coating (e.g., photoresist layer) 342 . In operation, the uniformized EUV radiation 12 ′ irradiates reflective reticle 336 and reflects therefrom, and the reticle pattern is imaged onto surface of photosensitive coating 342 of semiconductor wafer 340 by projection optical system 326 . In a lithography system 300 , the reticle image scans over the surface of photosensitive coating 342 to form the pattern over the exposure field. Scanning is typically achieved by moving reflective reticle 336 and semiconductor wafer 340 in synchrony. Once the reticle pattern is imaged and recorded on semiconductor wafer 340 , the patterned semiconductor wafer 340 is then processed using standard photolithographic and semiconductor processing techniques to form integrated circuit (IC) chips. Note that the components of lithography system 300 are shown lying along a common folded system axis AS in FIG. 23 for the sake of illustration. One skilled in the art will understand that there can be more than one fold in lithography system 300 , and that there can be an offset between entrance and exit axes for the various components such as for illuminator 20 and for projection optical system 326 . It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the spirit and scope of the disclosure. Thus it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

A collector system for extreme ultraviolet (EUV) radiation includes a collector mirror and a radiation-collection enhancement device (RCED) arranged adjacent an aperture member of an illuminator. The collector mirror directs EUV radiation from an EUV radiation source towards the aperture member. The RCED redirects a portion of the EUV radiation that would not otherwise pass through the aperture of the aperture member or that would not have an optimum angular distribution, to pass through the aperture and to have an improved angular distribution better suited to input specifications of an illuminator. This provides the illuminator with greater amount of useable EUV radiation than would otherwise be available from the collector mirror alone, thereby enhancing the performing of an EUV lithography system that uses such a collector system with a RCED.

FIELD OF THE INVENTION The invention generally relates to a process for maintaining a consistent surface on and extending the lifespan of a continuous rubber blanket. More specifically, the invention relates to a process and apparatus for continuously conditioning a continuous rubber blanket such as the variety used in the compressive shrinkage of webs of material. BACKGROUND Many textile fabrics, and in particular those made wholly or partly from cellulosic fibers, have a tendency to shrink undesirably as a result of becoming wet or undergoing conventional laundering processes. To obviate undesirable shrinking, many such fabrics are customarily treated using a compressive or compaction shrinkage process, in order to pre-shrink the fabrics and increase their stability. Examples of compressive shrinkage processes are described in U.S. Pat. No. 2,146,694 to Wrigley, et al. and U.S. Pat. No. 3,469,292 to Hojyo, U.S. Pat. No. 4,156,955 to Joy, and U.S. Pat. No. 4,446,606 to Lawrence et al, the disclosures of which are incorporated herein by reference. Also, a popular compressive shrinkage process is known by the tradename SANFORIZE. In compressive shrinkage processes, a fabric web is typically laid out over the working face of a thick endless rubber blanket so that it is free of folds or wrinkles. The rubber blanket is positioned on a plurality of rotatable rolls which support the blanket along its 10 bearing surface, and the blanket is typically conveyed along an endless path by way of a driven cylinder which contacts the outer blanket surface. In this way, the fabric web placed on the outer surface of the blanket is caused to be carried through a number of processing stations. First, the fabric is typically moistened, then it is compressed along with the blanket between a roll and a heated cylinder or shoe. As the fabric and blanket pass between the nip (i.e., the point of contact between the two contiguous elements) and the blanket is compressed, adjacent portions of the outer surface of the blanket are caused to be extended. As the blanket and fabric leave the roll, the blanket contracts, and the fabric is forced to follow suit. As a result, the yarns in the warp direction are caused to shorten, and the filling yarns are pushed upwardly, thereby mechanically shrinking the fabric. The fabric is then fed to a dryer, where it is dried in its preshrunk condition. Because the rubber blanket is endless, a web of fabric can be processed in a continuous manner. However, the surface of the rubber blanket must be cooled following contact with the heated cylinder before it again contacts the fabric web. Such cooling is generally performed by applying water to the blanket as it travels between the point of web removal and the point of untreated fabric web lay-down. Because too much moisture on the blanket can interfere with proper fabric conditioning, it is generally necessary that the amount of water on the blanket working surface be closely controlled. Generally this is performed by water removal rolls, which squeegee the excess water from the cooled blanket. Because it is important that the blanket stay properly lubricated, water is often added to the bearing surface of the blanket at various positions throughout the process, e.g., before the point of fabric lay-down and following contact of the blanket with the heated cylinder. As should be apparent, the rubber blankets are exposed to great stresses during the compression shrinkage process as a result of the repeated heating and cooling, the tensions at which the blanket must be run on the machine, the compression forces endured by going through the nip, and the repeated wetting operations. Under these conditions, the working surface of the blanket slowly oxidizes. This results in an increase in hardness and a decrease in wettability. In addition, finishes present on the fabric surface are often transferred to the rubber surface. Over a relatively short time this finish tends to form a glaze on the rubber surface, further decreasing the wettability and friction characteristics of the surface. As will be readily appreciated by those of ordinary skill in the art, the reduction in frictional characteristics on the web-contacting surface of the blanket reduces its effectiveness in gripping the fabric web. As a result, the surface characteristics of the blanket must be modified to restore its frictional characteristics in order that it can continue to properly and uniformly process fabrics. For example, in commercial applications, once the blanket hardness has been found to deviate upwardly or downwardly about 12% from its original level, blanket manufacturers recommend that the blanket be ground to remove the dead rubber on its surface. In this way, the surface of the blanket is prevented from becoming too slick or from losing its ability to grab hold of the fabric being treated. Such grinding is usually performed by stopping the machine and backing the rubber blanket up against a rotatable roll covered with abrasive material (e.g., grinding cloth or sandpaper), which grinds the working face of the rubber blanket until the dead rubber area has been removed. Typically the grinding process requires the removal of about a sixteenth of an inch of the blanket surface with each grinding. Because, for example, a blanket which begins at 3 inches thick usually must remain at least two inches thick to work effectively, the number of grindings is thus very limited. As a result, the life of the rubber blanket used in these types of apparatus can be undesirably short. It can also be appreciated that intermittent grinding of the blanket produces a surface that is variable over time, resulting in a greater amount of variability in compressive efficiency, and greater variability in the shrinkage characteristics of the final product. As the overall pre-shrinkage may need to be increased to avoid producing out-of-specification goods, the fabric yield will be less. In addition, small cuts and nicks in the blanket can form and grow over time due to oxidation and the constant stretching and releasing of the blanket rubber surface. When the blanket is ground, additional blanket thickness must be sacrificed in order to insure that all cracks are removed. This contributes to a shorter blanket life. During grinding of the blanket, production is halted, as the blanket must be ground dry to avoid premature decomposition or destruction of the grinding cloth or sandpaper. In addition, a considerable amount of rubber debris is formed due to the conventional grinding process. A heavy dusting of talc is typically applied during the grinding process, to reduce the friction and heat generated and to keep the blanket from becoming too sticky during the grinding operation. This talc and surplus rubber material must be cleaned from the blanket to prevent them from collecting on fabrics or materials being processed after the grinding operation. In addition, blankets typically require frequent cleaning to remove the build-up of baked-on fabric finishes, oils, and the like. Again, production must be halted so that the blanket may be cooled, and detergents applied. However, if such finishes and oils are not removed on a timely basis, they can adversely affect the process performance as well as contribute to the decomposition of the rubber blanket. The requirements of frequent cleaning and grinding prevent the rubber blanket machine from operating in-line with modern webprocessing equipment, which generally operate continuously, and which cannot economically be stopped to accommodate belt cleaning and grinding. A typical blanket grinding operation takes about 8 hours to perform, which is significant lost time from a fabric producer's perspective. Therefore, the grinding operation is recognized as being a significant source of machine downtime. One attempt to increase the lifespan of blankets in compressive shrinkage apparatus is described in U.S. Pat. No. 5,791,029 to Maker, the disclosure of which is incorporated herein by reference. The '029 patent describes a rubber blanket construction having a bearing face which is beveled. The patentee describes that this construction reduces the tendency of the edges of the blanket to curve upwardly when the blanket is tensioned to perform a grinding operation and reduces the tendency of the edges to crack. While this method may reduce the tendency of the blanket to crack, it does not overcome the need for frequent blanket cleaning and grinding. SUMMARY OF THE INVENTION The present invention is directed to a process and apparatus for continuously conditioning the working face of a rubber blanket such as that used on compressive shrinkage apparatus. As a result, the useful life of the blanket can be extended to a significant extent. (For purposes of this invention, the term “rubber blanket” is intended to encompass all blankets useful in compressive shrinkage type apparatus, whether they are substantially all rubber, partially rubber, made from synthetic rubber, or the like. Similarly, although the term “continuously conditioning” is used, it is to be noted that this terminology encompasses substantially continuous conditioning methods of a like nature as well, and in particular, when the user has elected to discontinue the conditioning briefly for various reasons.) Because the process of the instant invention can be readily incorporated into the regular machine processing operations (i.e., the web processing operation), the need for machine downtime to allow blanket grinding can be eliminated. This in turn enables the apparatus to be used more efficiently, by not requiring the machine downtime typically required for conventional blanket conditioning methods. In addition, existing compressive shrinkage machines can be readily retrofit to form the apparatus of the invention, thereby minimizing associated costs. The invention achieves the above-noted advantages through the provision of an abrasive device, and in particular an abrasive roll, on the apparatus such that the abrasive roll is in contact with the working surface of the rubber blanket during regular operation of the compressive shrinkage apparatus during its regular web treatment process. In this way, the abrasive roll can provide a low level of consistent grinding for continuous periods of time. In a preferred form of the process, the abrasive roll contacts the blanket at substantially all times during operation of the machine and advancement of the blanket. Alternatively, the abrasive roll could be provided to contact the blanket less than 100% of the time the blanket is advancing (although constant contact is generally preferred.) The speed of the abrasive roll relative to that of the working surface of the blanket can be adjusted to provide the desired amount of grinding. Preferably, only a small differential in speeds exists, such that a constant low level of grinding can be achieved. Similarly, the pressure of the abrasive roll against the blanket can be selected to achieve an optimal level of grinding. Furthermore, it is particularly preferred that the rotation of the abrasive roll is directly associated with the travel of the blanket, so that the grinding operation is halted simultaneously upon the cessation of blanket movement. In this way the formation of irregularities in the blanket surface as a result of the grinding operation can be minimized. In other words, in the embodiments of the invention where the grinding is directly associated with the blanket movement, the risk that the blanket will cease movement while grinding continues can be avoided (thereby avoiding the risk that irregular regions of greater grinding are formed.) Surprisingly, a working surface having characteristics indistinguishable from that of the usual high speed dry grinding using talc may be achieved and consistently maintained, even in the hot and wet conditions typically associated with compressive shrinkage processes. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of one embodiment of an apparatus of the instant invention. DETAILED DESCRIPTION In the following detailed description of the invention, specific preferred embodiments of the invention are described to enable a full and complete understanding of the invention. It will be recognized that it is not intended to limit the invention to the particular preferred embodiment described, and although specific terms are employed in describing the invention, such terms are used in a descriptive sense for the purpose of illustration and not for the purpose of limitation. With reference to the drawing, FIG. 1 illustrates one embodiment of apparatus according to the present invention. Although described specifically to correspond with the illustrated apparatus, it is noted that the features of the invention can be included with other similar types of apparatus having a continuous blanket and in particular, other types and configurations of compressive shrinkage apparatus. In addition, although described in connection with the compressive shrinkage of textile fabrics (such as woven, knit and nonwoven fabrics), it is noted that the invention would have application to other types of compressive shrinkage apparatus, such as those designed to process paper webs. The apparatus, shown generally at 10 , desirably includes many of the elements included in a conventional compressive shrinkage apparatus. In particular, the apparatus 10 desirably includes a first roll 12 , which cooperates with a heated drum 14 to form a nip 16 therebetween. The apparatus also desirably includes a tensioning roll 18 , an idler roll 20 , and water removal rolls 22 . A rubber blanket 24 is positioned so that it extends around the rolls 12 , 18 , 20 and 22 in the manner illustrated. In this way, the rolls define a continuous path through which the blanket 24 travels during the web processing operation. As illustrated, a web W is fed into the apparatus so that it extends in an overlying relationship to the web-contacting surface 24 a of the blanket. In this way, the web of material W is compressed between the nip roll 12 and the heated drum 14 along with the blanket 24 , so that it is compressively shrunk in a conventional manner. In the illustrated embodiment of the invention, a first roll 26 is placed in pressure contact with the web-contacting surface of the blanket 24 , and is allowed to be driven by the blanket at a synchronous surface speed. As will be appreciated by those of ordinary skill in the art, the surface texture and/or pressure at which the drive roll contacts the blanket enables the roll to be rotated upon an advancing motion by the blanket. Preferably, the surface of this first roll is abrasive (e.g. by way of a stippled or textured surface, or more preferably through the provision of grit particles on the surface of the roll.) This drive roll 26 is then differentially geared to a second abrasive roll 28 , also in pressure contact with the web-contacting surface of the blanket 24 , so that it is driven at an asynchronous surface speed to the blanket. First and second backup rolls 30 , 32 may also be provided in order to provide or increase pressure between the drive and abrasive rolls 26 , 28 . In this way, the abrasive roll 28 serves to remove a portion of the web-contacting surface 24 a of the blanket as the blanket circulates along its web-processing endless pathway. Therefore, grinding can be performed during the normal compressive shrinkage operation rather than as a separate operation. As will be appreciated by those of ordinary skill in the art, by increasing the pressure of the abrasive roll 28 against the blanket, the span of contact between the roll and blanket is increased, thereby also increasing the rate of grinding. Furthermore, the differential speed (defined as the magnitude of the difference in the surface speed between the first and second rolls 26 , 28 , divided by the surface speed of the faster abrasive roll and multiplied by 100 percent) may vary from about 2 to 95 percent, but should preferably lie in the range of 5 to 50 percent, and most preferably in the range of about 8 to 25 percent. The pressure of the abrasive roll against the blanket is preferably about 20 to about 2000 pounds, and more preferably about 100 to about 1500 pounds, and most preferably about 200 to about 1000 pounds, such pressures being selected depending on, among other things, the speeds at which the machine is to be run and the amount of grinding desired. The abrasive rolls may be geared together, but are preferably coupled by means of a synchronous (e.g. toothed) belt. However, other means for achieving the speed correlation between the rolls may be utilized within the spirit of the invention. As noted above, pressure of the abrasive rolls against the blanket is preferably achieved by use of a back-up roll, most preferably with an individual back-up roll for each abrasive roll. In this way, a nip is created with the blanket running therebetween, with the abrasive roll loaded against the back-up roll, preferably by means of air cylinders. Two nips are preferably created. Utilizing this arrangement and two abrasive rolls, one can increase the pressure at one nip relative to the other, to thereby determine which roll serves as the drive roll, and which serves as the conditioning roll. This may be done intermittently, if desired, in order that the blanket can be abraded in both the forward and reverse directions. As a further alternative, the abrasive roll 28 could be independently controlled by way of supplemental drive means, to grind the blanket while it proceeds through its regular web processing operation. However, the use of an abrasive roll which is rotated in response to blanket motion is preferred, since this reduces machinery complexity and reduces the opportunity for grinding-induced blanket defects. Furthermore, additional rolls could be utilized as desired, to provide additional amounts of and locations of grinding. In addition, although illustrated as being provided relatively close to the web take-off location, it is noted that the abrasive roll(s) can be provided anywhere other than web-contacting portions of the apparatus, within the scope of the invention. The drive and abrasive rolls each desirably have abrasive surfaces. In particular, the abrasive rolls are preferably coated with diamond grit in the range of 60 to 400 grit, and more preferably in the range of 100 to 220 grit. The grit is preferably bonded directly to the roll by means of a metal matrix, where the metal is resistant to corrosion. In a preferred form of the invention, the metal matrix is selected from the group consisting of nickel, chromium, other metals with similar physical characteristics, or combinations thereof. The grit used for the drive roll and the conditioning roll may be different, thus allowing abrasion with two different grit sizes if the functions of the drive and conditioning rolls are interchanged by varying the nip pressures. While a single roll may be used as a conditioning roll, (with a preferable surface speed of between 2 and 200 percent of blanket working surface speed) by driving the roll by means of a variable speed motor, or by belt or geared connection of drive elements of the compressive shrinkage apparatus itself, it is preferred that the conditioning roll be surface driven by the blanket, as this insures that the blanket is not accidentally damaged during a stoppage, when the roll might otherwise continue to rotate after the blanket has stopped. Surface driving of the conditioning roll also insures that the rate of conditioning is proportional to the blanket speed. Because the rate of blanket wear is also proportional to the blanket speed, the rate of conditioning and wear are balanced, insuring a consistent blanket surface. Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In addition, although specific terms are employed, they are used in a generic and descriptive sense and not for purpose of limitation, the scope of the invention being defined in the claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.

A method for continuous conditioning of a rubber blanket such as the type used on compressive shrinkage apparatus is described. The blanket includes an inner bearing surface defining a bearing face and an outer surface defining a web-contacting face. The web-contacting face is contacted under pressure with an abrasive conditioning roll while the blanket is in its regular, web treating operation. The blanket working face can thus be continuously conditioned without the need for lengthy machine stops. In this way, the conventional grinding and cleaning operations can be minimized or eliminated.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for preparing a chilled beverage product, which contains milk and a food acid. The process of the present invention provides a means for making smooth-textured, low viscosity beverage products which contain milk proteins and a food acid, but which exhibit little or no sedimentation. 2. Description of the Prior Art When formulating a flavored drink containing milk proteins at a low pH of between pH 3.5 and 4.5, which contains milk solids, whey proteins are generally favored because they are soluble under acidic conditions. Acidic, flavored drinks with casein proteins are known to be unstable and produce large amounts of casein precipitate. A process and formulation for flavored low pH milk protein-containing beverages, which provides for significantly improved stability of the casein proteins with 97 to 99% stability is herein disclosed. The explanation of the chemistry is below. Milk proteins are generally divided into two classes: casein and whey. Casein is generally recognized as being insoluble under acidic conditions around its isoelectric point of about 4.6. This property of milk proteins is well known and is generally exploited in the manufacturing of cheese. Whey protein is more stable in acid solution and tends to offer less of a precipitation problem. A pH of 4.0 or less is desired for the milk beverage, however, to prevent microbial activity and thus allow for a longer shelf life and to provide a basis for fruit flavor. Where a milk product which contains casein at a pH below 4.6 is desired, additional treatment is required such as the addition of stabilizers or other processes known in the art. Even these known processes have problems of precipitation over time, and require that the product be shaken prior to drinking. Food grade stabilizers such as pectin, propylene glycol alginate, carboxymethylcellulose, xanthan gum, locust bean and combinations thereof have been used to prevent the sedimentation and coagulation of the milk proteins and to improve stability of the beverages. It is reported that even when these food stabilizers are employed, beverage products containing milk proteins and acid or acidic juice at a pH below 4.5 tend to exhibit undesirable sedimentation/precipitation over time. It would be desirable to provide a stable acidic, milk based beverage product which shows enhanced stability with little or no sediment or precipitation. This product should be prepared with conventional processing techniques. The present invention discloses a composition and processing technique for an acidic, milk based beverage with enhanced stability. Known methods for combining acidic fruit juices with milk products have taken several general approaches. Most common is the addition of a stabilizer to the mixture to control precipitation of milk proteins at a lowered pH. U.S. Pat. No. 2,859,115 to Rivoche describes how mixing fruit juice with milk can cause milk proteins to precipitate, because the fruit juice lowers the pH of the beverage. The reference describes overcoming this problem through he use of stabilizers such as pectin. A food powder is mixed with a colloidal stabilizer such as pectin or algin in water, followed by the addition of an alkaline earth salt such as calcium carbonate. A dry acid powder, such as tartaric acid is then added to initiates gel formation. The stabilized mixture is then mixed with milk and stirred at a controlled shear so that the gel is broken up, and a desired viscosity is reached. Similar approaches are employed in U.S. Pat. No. 4,031,264 to Arolski, et al., U.S. Pat. No. 4,046,925 to Igoe, and U.S. Pat. No. 4,078,092 to Nishiyama, all employ similar methods of creating a gel-stabilized mixture, which viscosity is then adjusted by the controlled application of mechanical shear. In Arolski, et al., a fruit mash is mixed with milk and the ensuing coagulation is then controlled by the addition of pectin as a stabilizer. The mixture is stirred and sterilized prior to storage. Igoe involves the formulation of a thickening agent from carboxymethyl cellulose, locust bean gum and xanthan gum in admixture. This stabilizer, with sugar, is added to milk, followed by the addition of fruit juice. In Nishiyama sodium carboxymethyl cellulose is added to the fruit juice first to form a juice composition which can then be added to milk to produce a stable milk product. U.S. Pat. No. 5,648,112 to Yang, et al. describes mixing milk with a food stabilizer under high shear mixing conditions and maintaining a median particle size of less than 0.8 microns to prevent precipitation of milk proteins. Afterward, the pH is reduced to between 3.2 and 4.5 by the addition of food grade acid. U.S. Pat. No. 3,692,532 to Shenkenburg, et al. describes a process whereby a stabilizer having carboxyl groups is added to milk, followed by the addition of fruit juice. According to the process disclosed, sugar and carboxymethyl cellulose are mixed with milk, and sufficient time allowed for the carboxyl groups of the stabilizer to react with the casein. The described reaction is said to occur at temperatures below 90° F., and the resulting mixture is aged, pasteruized and homogenized. The resulting product is stated to be stable at a pH below 5.0. Another approach to creating a stable milk and fruit juice beverage is employed in U.S. Pat. No. 4,520,036 to Rialland, et al., and U.S. Pat. No. 4,676,988 to Efstathiou, et al. These two refernces describe a process whereby milk is passed through a cation exchange resin. The pH of the milk is thus lowered to a value 3.8 (Rialland, et al.) and to between 3.2 and 1.5 (Efstathiou, et al.). Lastly, U.S. Pat. No. 4,416,905 to Lundstedt, et al. describes permitting milk to ferment and achieve a pH in the range between 6.2 to 4.9 and then acidifying the beverage to a pH below 4.7, to produce a better tasting butter milk product SUMMARY OF THE INVENTION It is therefore the object of the present invention to provide a milk protein beverage which contains milk proteins and a food acid, said beverage having a long shelf life and exhibiting little or no sedimentation over time. It is a further object of the present invention to provide a means for making a milk protein beverage which contains milk proteins and a food acid, said beverage having a long shelf life and exhibiting little or no sedimentation over time. It is a further object of the present invention to provide a nutritious and flavorful milk protein beverage which exhibits a smooth texture and a low viscosity, and a means for making same. The present invention relates to a composition and a process for preparing an acidic milk protein based beverage product. The products prepared according to the process of the present invention are stable and do not show sediment or precipitate over time. These products contain from about 0.5% to 5.0% milk proteins and 0.5 to 2.0% of a food stabilizer mixture and a food acid sufficient to lower the pH below 4.5. The present invention comprises concentrated milk protein which is a dry powder which is reconstituted with water to form a solution of milk proteins, specifically casein and whey. The milk protein may be substituted with other milk products, such as whole milk, skim milk, dehydrated milk powder, etc. The process of the present invention comprises, as a first step, mixing the milk proteins with a weak base to elevate the pH. The weak base can be a salt of a weak organic acid, such as sodium citrate, sodium malate, sodium lactate or sodium fumerate. Sodium citrate is the preferred weak base additive. The sodium citrate is added to the concentrated milk protein in sufficient amounts to raise the pH to a range of 7.0 to 8.0. The addition of weak base creates an environment wherein the casein molecules are enhanced in a manner which promotes the association of stabilizer molecules to the surface of the protein. The basic environment also reduces the role of calcium by inhibiting the bridging of calcium with the protein, thus limiting coalescence and sedimentation of the proteins. Stabilizers are then added to the mixture. Stabilizers employed in the invention include pectin, propylene glycol alginate and others, which consist of acidic hydrocolloids. These acidic hydrocolloids are negative charged bodies when present in the basic environment. The negatively charged hydrocolloids adhere to the surface of casein molecules, forming colloidal complexes which are themselves negatively charged. These colloidal complexes resist agglomeration, and thus remain in stable suspension in the mixture, even at low pH and low viscosity. The food stabilizer is added under low shear conditions sufficient to form an intimate mixture. These conditions avoid excessive shear for extended periods of time, which can act to break up the negatively charged colloidal complexes, denature the milk proteins and cause foam. Upon formation of the negatively charged colloidal complexes which effectively stabilize the milk proteins, optional ingredients, such as flavors, colors, sweeteners, vitamin and mineral supplements, microbiological stabilizers, etc. may then be added. The mixture is then homogenized and cooled below 30° C., preferably below 10° C. Acid is then added under low shear conditions to the cooled mixture. A food grade acid such as citric acid is added to bring the pH down to between 3.2 and 4.5. The acid is added in a chilled state, generally below 10° C. Mixing remains under low-shear conditions, so as not to break up the stable colloidal complexes. The final product is then packaged and may stored at room temperature or refrigerated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention relates to a formulation and process for preparing acidic milk based beverage products which develop little of no sediment or precipitation over time. The beverages provide the milk appearance and the flavor of a fruit flavored milk drink at a low viscosity, thus providing a refreshing and rich beverage which is unique. Generally, milk products are formulated at a high pH to avoid sedimentation and precipitation. Milk proteins are known to be unstable at low pH. The stability of the protein must be enhanced with food grade stabilizers or gums, which coat the surface of the protein and inhibit the sedimentation. Mixing of the milk protein with a weak base enhances the structure of the casein proteins and improves the coating of the casein particle with the stabilizing gums. The weak base also can reduce the role of calcium in promoting the coalescence and sedimentation of milk proteins. The stabilizers can be predissolved in water or added directly to the alkaline milk protein base under low shear conditions, to produce the intimate mixture of milk proteins and stabilizers. Optional ingredients are added and the mixture is homogenized to ensure a uniform mix and dispersion. Acid is added under cooled conditions to a pH below 4.5. Particular ingredients and processing steps are described below. A. Process Materials The materials employed in the process of the present invention include milk or concentrated milk protein, a weak base, a food acid and food stabilizer, as well as other optional ingredients. These are described more particularly as follows: 1. Milk The milk proteins used in the process of the present invention may be derived from all forms of milk including, but not limited to, whole milk, skim milk, milk powder, concentrated milk proteins and whey. The milk proteins can be from a dairy ingredient of any form: native, homogenized, concentrated or powder. The amount of milk protein employed in the formulation of the present invention and present in the final beverage products will typically range from about 0.5% to about 5.0% preferably from about 1.0% to about 4.0% which is equivalent to the protein content of native milk. 2. Weak Base The formulation and process employ a weak base to condition the structure of the milk proteins for coating with food stabilizers. The weak base can be salts of weak organic acids like sodium citrate, sodium malate, sodium lactate, or sodium fumarate. Sodium citrate is preferred. Typically, when this is added to the milk proteins, the resulting pH is within a range of 7.0 to 8.0, preferably 7.3-7.7. 3. Food Acid The process of the present invention also employs a food acid. The food acid can include any food grade organic or inorganic acid, for example, citric acid, malic acid, lactic acid, gluconic acid, succinic acid, tartaric acid, phosphoric acid, fumaric acid, and ascorbic acid. Aliphatic hydroxycarboxylic acids (e.g., malic acid, lactic acid, and citric acid) are typicially preferred for use herein. Citric acid is most preferred for use herein. The amount of acid employed is an amount sufficient to adjust the pH of the milk/stabilizer mixture to from about 3.2 to about 4.5, preferably from about 3.5 to about 4.5, most preferably from about 3.8 to about 4.2. Where the acid used is citric acid, typically the citric acid is added in an amount ranging from about 0.3% to about 1.0% by weight of the beverage, preferably between 0.5 to 0.8%. 4. Stabilizer The various food stabilizers which can be employed in the present invention include hydrophilic colloidal stabilizers commonly known in the art such as gum arabic, gelatin, xanthan, locust bean, propylene glycol alginate, and pectin, as well as anionic polymers derived from cellulose (e.g., carboxymethylcellulose), which are water soluble and tolerant of low pH's. A blend of pectin and propylene glycol alginate is typically preferred for use herein. The stabilizer is typically used in an amount ranging from about 0.1% to about 2.0% by weight of the beverage, preferably from about 0.3% to about 1.0%. The amount of stabilizer used is dependent in part on the level of milk solids present in the beverage product. In general, the greater the level of milk solids present in the beverage, the more stabilizer that will be required to stabilize the beverage. The mixture of stabilizers can be adjusted to provide low beverage viscosity and stability of the milk proteins. 5. Other Ingredients Acid dairy beverages usually are formulated to provide a base for fruit flavored products. The fruit flavor can be supplied from fruit juice, fruit concentrates, or flavors, as desired. The formulation of the present invention can also employ a sweetener. The sweetener can include, for example, maltose, sucrose, glucose, fructose, invert sugars and mixtures thereof. These sugars can be incorporated into the beverage products in solid or liquid form, but are typically incorporated as a syrup, more preferably as concentrated syrup such as high fructose corn syrup. For purposes of preparing the beverage products described herein, these optional sweeteners can be provided to some extent by other components of the beverage products, such as by the fruit juice component. Sweeteners are typically employed in the process of the present invention in amounts ranging from about 0.0% to about 15%. Preferred carbohydrate sweeteners for use in the process of the present invention are sucrose, fructose and mixtures thereof. Fructose can be obtained or provided as liquid fructose, high fructose corn syrup, dry fructose or fructose syrup, but is preferably provided as high fructose corn syrup. High fructose corn syrup (HFCS) is commercially available as HFCS-42, HFCS-55 and HFCS-90, which comprise 42%, 55% and 90%, respectively, by weight of the sugar solids therein as fructose. Artificial or noncaloric sweeteners for use in the formulation of the present invention include, for example, saccharin, cyclamates, acetosulfam, L-aspartyl-L-phenyalanine lower alkyl ester sweeteners (e.g., aspartame). A particularly preferred sweetener is aspartame. They may be used as the sole source of sweetness or in combination with caloric sweeteners discussed above. Artificial or noncaloric sweeteners, if used, are typically employed in an amount ranging from about 0.02% to about 1%, preferably from about 0.02% to about 0.10% by weight of the beverage products. The process of the present invention can also optionally employ a preservative. Any food grade preservative can suitably be used in the process of the present invention. Suitable preservatives include sorbic acid, benzoic acid, alkali metal salts thereof, and mixtures thereof. Preferred preservatives include sodium benzoate and potassium sorbate. The preservative is typically present in an amount ranging from about 0.01% to about 0.10% by weight of the beverage product, depending on the method and temperatures of commercial distribution. The formulation of the present invention can also be fortified with various vitamins and minerals. B. Process Steps Milk proteins are added to a solution of a weak base. If the milk protein are in the dry form sufficient time is provided for a uniform dispersion and hydration. This time is highly dependent on the temperature of the solution. At 35° C., two minutes at high shear and 10 minutes at low shear are sufficient to provide a uniform dispersion. The resulting mixture has an elevated pH, which is within a range of 7.0 to 8.0, preferably 7.3 to 7.7. Stabilizers perform best when they are prepared by dispersion and hydration in heated water before the addition to milk proteins. This can be accomplished by many combinations of time, temperature, and shear and depends on the stabilizers employed. For the preferred pectin and propylene glycol alginate mixture, it is desirable to use heated water at a temperature between 55° C. and 75° C. Under high shear conditions, 5 minutes is sufficient to disperse and hydrate the stabilizers. Under low shear conditions, 20 minutes is sufficient to disperse and hydrate the stabilizers. The fully hydrated stabilizers are added to the alkaline milk proteins employing low shear and sufficient time to ensure a complete mixture. Optional ingredients can then be added to the weak base/milk protein/stabilizer mix. If these ingredients are in dry form like sodium benzoate, etc., care should be taken to ensure a complete solution is achieved. The unacidified mix is homogenized under conventional conditions. A two-stage piston homogenizer can be employed at 500/2000 homogenization pressures. The homogenization pressures are not critical to the process and should be sufficient to provide a smooth homogenous mix. Acid can then be added to the homogenized mixture with low shear. It is beneficial to dissolve powdered acids before there addition to the protein mixture. This provides a better mixing of the acid with the protein under low shear conditions. The mix should be cooled before the addition of acid to below 30° C., preferably below 10° C. The acid is similarly cooled to between 1° C. and 30° C. Acid addition rate is not critical to the stability of the mix. EXAMPLES Example 1 Ingredients are used in the following proportions. Ingredients Weight % Water 90.56 Aspartame 0.04 Milk protein 2.35 Sodium citrate 0.34 Vitamin premix 0.15 Sodium benzoate 0.01 Potassium sorbate 0.01 High fructose corm syrup 4.89 Propylene glycol alginate 0.46 Pectin 0.21 Citric acid 0.68 Flavor 0.19 Color 0.12 A tank with high shear is beneficial for completely dispersing and dissolving dry ingredients. Initially, 30 pounds of sodium citrate is dissolved in 3500 pounds of water at 35° C. this is followed by the addition of 208 pounds of dried milk protein concentrate to the sodium citrate solution. The solution is mixed for 2 minutes under high shear, and then is transferred to a larger tank with a low shear mixer for the addition of other ingredients. In a separate vessel, 41 pounds of propylene glycol alginate and 19 pounds of pectin are dissolved in 2000 pounds of water at 65° C. and mixed for 5 minutes. The stabilizers are added to the alkaline milk protein. The remainder of all the other ingredients except the acid are pre-dissolved in 1500 pounds of water and mixed for 2 minutes. The mix is then homogenized in a two-stage piston homogenizer with back pressures of 500/2000 psi. The mix is cooled to less than 5° C. and the chilled acid (below 5° C.) is added to the homogenized mix with a low shear mixer. The resulting product exhibits little or no sediment. Thus, the several aforementioned objects and advantages are most effectively attained. Although a single preferred embodiment of the invention has been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.

Acidic milk based beverage products which do not precipitate over time and are physically stable, and a process for preparing these products, are disclosed. These products contain from about 0.5% to 5.0% milk proteins and 0.1 to 2.0% of a food stabilizer and a food acid sufficient to lower the pH below 4.5. The first step of the process involves mixing milk proteins with a food grade weak base to raise the pH above 7.0. Food grade stabilizers are added to the elevated pH mixture of milk proteins and base under low shear conditions. Other ingredients are then added to provide the desired sweetness, flavor, color and microbiological stability. This mixture is homogenized before acidification. A chilled food grade acid is then added at a temperature below 30° c. under low to moderate shear conditions.

CLAIM OF PRIORITY [0001] This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. § 119 from an application for CHASSIS STRUCTURE FOR PLASMA DISPLAY MODULE, AND PLASMA DISPLAY MODULE COMPRISING THE SAME, earlier filed in the Korean Intellectual Property Office on Dec. 10, 2004 and there duly assigned Ser. No. 10-2004-0104035. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a chassis structure for a plasma display module and a plasma display module including the plasma display module, and more particularly, to a chassis structure for a plasma display panel that effectively dissipates heat generated by a plasma display panel and improves assembly of the plasma display module, and a plasma display module including the chassis structure. [0004] 2. Description of the Related Art [0005] In general, a plasma display panel is a flat panel display apparatus displaying images using a gas discharge phenomenon. Some of the advantages of the plasma display panel are a large screen with large viewing angle, small thickness, and high image quality. In the plasma display apparatus, a discharge occurs between electrodes due to a Direct Current (DC) or Alternating Current (AC) voltage supplied to the electrodes, and ultraviolet rays generated due to the gas discharge excite a phosphor material to emit visible light. [0006] A plasma display module the plasma display module includes a plasma display panel, a plurality of circuit boards, on which circuits for driving the plasma display panel are mounted, and a chassis supporting the plasma display panel and the circuit boards. [0007] The plasma display panel and the chassis are attached to each other via a dual-adhesive unit attached on a back surface of the plasma display panel, and the dual-adhesive unit is generally a dual-adhesive tape. [0008] A heat dissipation sheet having excellent thermal conductivity is disposed between the plasma display panel and the chassis to dissipate the heat generated during driving the plasma display panel to the chassis. [0009] The chassis is generally formed of metal such as aluminum, and is fabricated in a casting or a press process. [0010] A circuit device is mounted on the circuit board, and the circuit board is mounted on the chassis using a boss and a screw bolt. [0011] However, the chassis of such a plasma display module does not include a heat dissipation structure, and thus, it is difficult to effectively dissipate the heat transmitted to the chassis from the plasma display panel. [0012] In addition, since the base portion of the chassis is formed as a single plate, processes for fabricating the boss having a female screw unit and pressing the boss 0 into the chassis to install the boss are required so as to fix the circuit boards onto the chassis. Therefore, the number of processes for assembling such a plasma display module is increased, and thus, fabrication of the plasma display module is expensive and time-consuming. SUMMARY OF THE INVENTION [0013] The present invention provides a chassis structure for plasma display module, which is capable of effectively dissipating heat generated by a plasma display panel and improving assembly of the plasma display module, and a plasma display module including the chassis structure. [0014] According to one aspect of the present invention, a chassis structure for a plasma display module is provided, the chassis comprising: a front plate; a back plate separated from the front plate; and a heat dissipation member arranged between the front plate and the back plate, and having a bent cross-section arranged so that some surfaces of the heat dissipation member contact the front plate and some surfaces of the heat dissipation member contact the back plate to allow air flow between the front and back plates. [0015] The heat dissipation member preferably comprises a serpentine cross-section. The heat dissipation member alternatively preferably comprises a convex-concave cross-section. The heat dissipation member preferably comprises a heat conductive material. [0016] According to another aspect of the present invention, a plasma display module is provided comprising: a plasma display panel; at least one circuit board adapted to drive the plasma display panel; a front plate adapted to support the plasma display panel; a back plate adapted to support the at least one circuit board and separated from the front plate; and a heat dissipation member arranged between the front plate and the back plate, and having a bent cross-section arranged so that some surfaces of the heat dissipation member contact the front plate and some surfaces of the heat dissipation member contact the back plate to allow air flow between the front and back plate. [0017] The plasma display module preferably further comprises a heat dissipation sheet arranged between the plasma display panel and the front plate. [0018] The heat dissipation member preferably comprises a serpentine cross-section. The heat dissipation member alternatively preferably comprises a convex-concave cross-section. The heat dissipation member preferably comprises a heat conductive material. [0019] The back plate preferably comprises an aperture adapted to fix the circuit board thereon. [0020] The plasma display module preferably further comprise a connection unit adapted to fix the at least one circuit board on the back plate, wherein a first end of the connection unit is arranged on the at least one circuit board, and wherein a second end of the connection unit passes through the aperture to be arranged in a space between the front and back plates. [0021] The second end of the connection unit preferably comprises a tapered wing. The connection unit preferably comprises a synthetic resin. BRIEF DESCRIPTION OF THE DRAWINGS [0022] The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: [0023] FIG. 1 is a perspective view of a plasma display module; [0024] FIG. 2 is a cross-sectional view of the plasma display module taken along line II-II of FIG. 1 ; [0025] FIG. 3 is a cross-sectional view of a chassis structure of a plasma display module according to a first embodiment of the present invention; [0026] FIG. 4 is a perspective view of a heat dissipation member according to the first embodiment of the present invention; [0027] FIG. 5 is a cross-sectional view of a modified example of chassis structure of the plasma display module according to the first embodiment of the present invention; [0028] FIG. 6 is a perspective view of a modified example of the heat dissipation member according to the first embodiment of the present invention; [0029] FIG. 7 is a perspective view of another modified example of the heat dissipation member according to the first embodiment of the present invention; and [0030] FIG. 8 is a partial cross-sectional view of a chassis structure of a plasma display module according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION [0031] FIG. 1 is a perspective view of a plasma display module in a plasma display apparatus, and FIG. 2 is a cross-sectional view of the plasma display module taken along line II-II of FIG. 1 . [0032] Referring to FIG. 1 , the plasma display module 100 includes a plasma display panel 100 , a plurality of circuit boards 120 , on which circuits for driving the plasma display panel 110 are mounted, and a chassis 130 supporting the plasma display panel 110 and the circuit boards 120 . [0033] The plasma display panel 110 and the chassis 130 are attached to each other via a dual-adhesive unit 140 affixed to a back surface of the plasma display panel 110 , and the dual-adhesive unit 140 is generally a dual-adhesive tape. [0034] A heat dissipation sheet 150 having excellent thermal conductivity is disposed between the plasma display panel 110 and the chassis 130 to transmit the heat generated during the driving of the plasma display panel 110 to the chassis 130 . [0035] The chassis 130 is generally formed of metal such as aluminum, and is fabricated by casting or pressing. [0036] A circuit device is mounted on the circuit board 120 , and the circuit board 120 is mounted on the chassis 130 using a boss 160 and a screw bolt 170 . [0037] However, the chassis 130 of the plasma display module 100 does not include a heat dissipation structure, and thus, it is difficult to effectively dissipate the heat transmitted to the chassis 130 from the plasma display panel 110 . [0038] In addition, since the base portion of the chassis 130 is formed as a single plate, processes for fabricating the boss 160 having a female screw unit and pressing the boss 160 into the chassis 130 to install the boss 160 are required so as to fix the circuit boards 120 onto the chassis 130 . Therefore, the number of processes for assembling the plasma display module is increased, and thus, fabrication of this plasma display module is expensive and time-consuming. [0039] Referring to FIGS. 3 and 4 , a plasma display module 200 according to a first embodiment of the present invention includes a plasma display panel 210 , a plurality of circuit boards 220 , on which circuits for driving the plasma display panel 210 are mounted, and a chassis 230 supporting the plasma display panel 210 and the circuit boards 220 . [0040] The chassis 230 includes a front plate 231 , a back plate 232 , and a heat dissipation member 233 . [0041] The plasma display panel 210 and the front plate 231 are attached to each other by a dual-adhesive unit 240 affixed to a back surface of the plasma display panel 210 , and a circuit device 221 is disposed on the circuit board 220 . [0042] A heat dissipation sheet 250 is disposed between the plasma display panel 210 and the front plate 231 to transmit heat generated by the plasma display panel 210 to the front plate 231 . [0043] The back plate 232 is separated a predetermined distance from the front plate 231 , and the predetermined distance can be determined by a designer of the module in consideration of the heat dissipating performance and thickness of the plasma display module 200 . [0044] In FIGS. 4 and 5 , the heat dissipation member 233 is located between the front plate 231 and the back plate 232 , and has a serpentine cross-section. In addition, the heat dissipation member 233 is formed of a thermally conductive material, that is, generally metal. [0045] Ridge portions 234 of the heat dissipation member 233 contact the front plate 231 and the back plate 232 . In addition, valley portions 235 at the opposing side of the ridge portions 234 , the front plate 231 , and the back plate 232 form air flow paths 280 . Therefore, some of the heat transmitted to the heat dissipation member 233 is transmitted to the air flowing in the air flow paths 280 to be dissipated, and the residual heat transmitted to the heat dissipation member 233 is transmitted to the back plate 232 and dissipated. [0046] It is desirable that the heat dissipation member 233 bent with a constant curvature is disposed between the front plate 231 and the back plate 232 , and then, these elements are brazed together. [0047] The circuit board 220 is mounted on the back plate 232 using a boss 260 and a screw bolt 270 . [0048] The operation of the chassis structure according to the first embodiment of the present invention is as follows. [0049] When the plasma display module 200 is driven, a lot of heat is generated by the plasma display panel 210 . The generated heat is transmitted to the front plate 231 after passing through the heat dissipation sheet 250 . [0050] The heat transmitted to the front plate 231 is transmitted to the heat dissipation member 233 . Since the heat dissipation member 233 has a serpentine cross-section, a surface area of the heat dissipation member 233 is large, and a plurality of air flow paths 280 are formed, and thus, a large amount of the heat transmitted to the heat dissipation sheet 233 is dissipated out of the chassis 230 . [0051] That is, since the edges of the chassis 230 are open, external air can be induced and discharged into/out of the chassis 230 . The air induced in the chassis 230 absorbs the heat while contacting the heat dissipation member 233 , and then, is exhausted out of the chassis 230 . Thus, a large amount of the heat transmitted to the heat dissipation member 233 can be exhausted effectively out of the chassis 230 by the air induced in the chassis 230 . [0052] In addition, the residual heat transmitted to the heat dissipation member 233 is transmitted to the back plate 232 and dissipated. [0053] That is, according to the first embodiment of the present invention, the chassis 230 includes the front plate 231 , the back plate 232 , and the heat dissipation member 233 , and the heat generated by the plasma display panel 210 is effectively dissipated by the heat dissipation member 233 . [0054] Hereinafter, a modified example of the above chassis structure according to the first embodiment of the present invention is described with reference to FIGS. 5-7 , and different elements from those of the above example are described. [0055] FIG. 5 is a cross-sectional view of a modified example of chassis structure of the plasma display module according to the first embodiment of the present invention, and FIG. 6 is a perspective view of a modified example of the heat dissipation member according to the first embodiment of the present invention. [0056] The plasma display module 300 includes a plasma display panel 310 , circuit boards 320 , and a chassis 330 . [0057] The chassis 330 includes a front plate 331 , aback plate 332 , and a heat dissipation member 333 , and the plasma display panel 310 is supported at the front plate 331 using a dual-adhesive unit 340 . [0058] Compared to the above first embodiment, the modified example of the first embodiment has a heat dissipation member 333 of a different shape than that of the heat dissipation member 233 of FIGS. 3-4 . [0059] That is, unlike the heat dissipation member 233 having the serpentine cross-section, the modified heat dissipation member 333 has a convex-concave cross-section. [0060] The heat dissipation member 333 is formed of a thermally conductive material. Ridge portions 334 of the heat dissipation member 333 contact the front plate 331 and the back plate 332 . Valley portions 335 at the opposing side of the ridge portions 334 , the front plate 331 , and the back plate 332 form air flow paths 380 . [0061] Therefore, the heat generated by the plasma display panel 310 is transmitted to the front plate 331 through the heat dissipation sheet 350 . A large amount of the heat transmitted to the front plate 331 is transmitted to the heat dissipation member 333 , and some of the heat transmitted to the heat dissipation member 333 is absorbed by the air flowing in the air flow paths 380 to be dissipated, and the residual heat transmitted to the heat dissipation member 333 is transmitted to the back plate 332 and dissipated. [0062] FIG. 7 is a perspective view of another modified example of the heat dissipation member according to the first embodiment of the present invention. The heat dissipation member 433 is formed by slightly changing the shape of the heat dissipation member 333 of FIG. 6 . That is, connections between ridge portions 434 and valley portions 435 are slanted. [0063] The elements of the modified examples of the heat dissipation member perform the same functions as those of the elements in the dissipation member of the first embodiment. However, the heat dissipation members 333 and 433 of FIGS. 5-7 have larger ridge portions 334 and 434 contacting the front and back plates 231 and 232 than those of the heat dissipation member 233 of the first embodiment. Therefore, the heat dissipation members 333 and 433 have some different characteristics from those of the heat dissipation member 233 in that the heat from the plasma display panel can be easily transmitted to the heat dissipation members 333 and 433 and that the heat dissipation members 333 and 433 have relatively smaller heat dissipation surface area. [0064] Hereinafter, a plasma display module according to a second embodiment of the present invention is described with reference to FIG. 8 . [0065] The plasma display module 500 according to the second embodiment of the present invention includes a plasma display panel 510 , a plurality of circuit boards 520 , on which circuits driving the plasma display panel 510 are mounted, and a chassis 530 supporting the plasma display panel 510 and the circuit boards 520 . [0066] The chassis 530 includes a front plate 531 , a back plate 532 , and a heat dissipation member 533 . [0067] The plasma display panel 510 and the front plate 531 of the chassis 530 are attached to each other by a dual-adhesive unit 540 affixed to a back surface of the plasma display panel 510 . [0068] A heat dissipation sheet 550 is disposed between the front plate 531 and the plasma display panel 510 to transmit the heat generated by the plasma display panel 510 to the front plate 531 . [0069] The back plate 532 is separated a predetermined distance from the front plate 531 , and a heat dissipation member 533 is located between the front plate 531 and the back plate 532 . In addition, air flow paths 580 are formed by the front plate 531 , the back plate 532 , and the heat dissipation member 533 . [0070] The heat dissipation member 533 has the same structure and function as those of the heat dissipation member 433 of the previous embodiment. [0071] That is, the heat generated when the plasma display panel 510 is driven is transmitted to the heat dissipation member 533 after passing through the heat dissipation sheet 550 , and some of the heat transmitted to the heat dissipation member 533 is absorbed by the air flowing in the air flow paths 580 and dissipated, and the residual heat is transmitted to the back plate 532 and dissipated. [0072] In addition, the back plate 532 includes holes 590 for fixing the circuit boards 520 , and the circuit boards 520 are fixed on the back plate 532 by connection units 570 . [0073] The connection unit 570 is formed of synthetic resin. In addition, a first end 571 of the connection unit 570 is mounted on the circuit board 520 , and a second end 572 of the connection unit 570 passes through the hole 590 formed on the back plate 532 and is located in the space between the front plate 531 and the back plate 532 . [0074] The second end 572 of the connection unit 570 includes a wing part 573 having tapered shape, and thus, it can be only inserted into the hole 590 formed on the back plate 532 in one direction, and when the second end 572 of the connection unit 570 is inserted into the hole 590 , the wing part 573 is bent inward. [0075] After the wing part 573 of the connection unit 570 passes through the hole 590 , the wing part 573 is recovered to the original status by an elastic force, and thus, the second end 572 of the connection unit 570 is located between the front plate 531 and the back plate 532 . Therefore, the second end 572 of the connection unit 570 and a suspending step 574 can fix the circuit board 520 onto the back plate 532 . [0076] In addition, referring to FIG. 8 , it is desirable that the end 572 of the connection unit 570 is located toward the valley portion of the heat dissipation member 533 avoiding from the ridge portion of the heat dissipation member 533 . [0077] Therefore, in order to assemble the plasma display module 500 according to the second embodiment of the present invention, the circuit board 520 can be firmly fixed on the back plate 532 simply by mounting the first end 571 of the connection unit 570 on the circuit board 520 and pushing the second end 572 of the connection unit 570 into the hole 590 of the back plate 532 . Therefore, a process of forming the boss on the chassis for fixing the circuit board on the chassis is not necessary. [0078] The assembling way of the plasma display module 500 according to the second embodiment of the present invention cannot be applied to a conventional plasma display module, in which the chassis is formed as a single plate, since the second end 572 of the connection unit 570 collides with the plasma display panel in the conventional plasma display module even if the connection unit 570 is inserted after forming the hole on the chassis. Therefore, the connection unit 570 cannot be fixed on the chassis of the conventional plasma display module. That is, since the chassis of the conventional plasma display module is formed as a single plate, there is no space to receive the second end 572 of the connection unit 570 , and thus, the connection unit 570 cannot be fixed on the chassis in the conventional plasma display module. [0079] According to the plasma display module of the second embodiment of the present invention, since the chassis 530 includes the front plate 531 , the back plate 532 , and the heat dissipation member 533 , the heat dissipation member 533 can effectively dissipate the heat transmitted to the front plate 531 . In addition, the circuit boards 520 can be mounted on the back plate 532 in easy and effective way by using the space between the front plate 531 and the back plate 532 and the connection unit 570 . [0080] As described above, according to the present invention, the chassis includes the front plate, the back plate, and the heat dissipation member, and thus, the heat generated by the plasma display panel can be dissipated using the heat dissipation member. [0081] In addition, since the front plate and the back plate are separated a predetermined distance from each other, the circuit board can be mounted on the back plate in easy and effective way using the connection unit, and the assembling convenience of the plasma display module can be improved. Therefore, the production time and manufacturing costs can be reduced. [0082] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various modifications in form and detail can be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

A chassis structure for a plasma display module, and a plasma display module including the chassis structure effectively dissipate heat generated by a plasma display panel and improve assembly of the plasma display module. The chassis base includes: a front plate; a back plate separated from the front plate; and a heat dissipation member disposed between the front plate and the back plate, and having a bent cross-section arranged so that some surfaces of the heat dissipation member contact the front plate and some surfaces of the heat dissipation member contact the back plate to allow air flow between the front and back plate.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority from United States Provisional Patent Application Serial 60/441,097 filed Jan. 17, 2003; the disclosures of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. TECHNICAL FIELD [0003] The invention relates generally to merchandise display systems. More particularly, the invention relates to a merchandise display system that is lockable to prevent the merchandise from being removed. Specifically, the invention relates to such a system wherein merchandise can be handled and viewed by the consumer while remaining locked to thwart shoplifting. [0004] 2. BACKGROUND INFORMATION [0005] In seeking out products to buy, consumers have a natural desire to be able to handle and view the products for making their purchase. However, vendors naturally have a concern that products will be stolen. As a result, vendors desire merchandise displays which are lockable to prevent such theft. The problem that arises is that merchandise display assemblies do not generally allow the consumer to easily handle and view products without the merchandise assembly being unlocked first. [0006] Thus, the art needs a merchandise assembly which is both lockable to prevent theft and also allows the consumer to easily handle and view the product without the need for the vendor to unlock the display assembly until the consumer has already made the decision to purchase the product. The merchandise display assembly of the present invention solves this problem by allowing merchandise to hang from a display rod by a hanging assembly which allows the merchandise to pivot and swivel freely such that the consumer can handle the product and see it from nearly every angle. [0007] U.S. Pat. No. 3,495,716 to Gregory discloses a stereo tape display holder which includes a lockable case to hold the tape, the case having openings in an end wall and side walls thereof through which printed data on the tape may be viewed. A swivel means includes a first annular link coaxially connected to a boss on the case by a bolt or rivet and a second annular link rotatably connected to the first link by a rivet. The second link encircles a rod of a wire display rack sitting atop a display cabinet. The swivel means allows rotation about an axis so that the lockable case is rotatable about said axis with respect to the second link. The rod is freely received by the second link so that the second link may easily slide along and rotate about the rod. This configuration allows the lockable case to be lifted upwardly from the display rack in pivoting relation to the rod and rotated about the axis to facilitate viewing by a consumer. [0008] The configurations disclosed in the Gregory patent leave a variety of areas for improvement. First, the Gregory swivel means rotates about only one axis, so that the swivel means and case must rotate about the rod to allow rotation about a second axis. Applicants' invention, by contrast, includes a swivel which itself allows rotation about first and second axes perpendicular to one another. Thus, Applicants' swivel assembly enhances the ability to maneuver the display case as desired. [0009] Further, the first link of Gregory's swivel means is connected to the display case by a bolt or rivet and the first and second links are attached by a rivet, thus making the case and swivel inseparable, whereas Applicants' invention provides a variety of options whereby the use of a rivet and the like is eliminated and portions of the swivel assembly are separable from one another to allow removal of the display case from the rod assembly. Applicants' ball and socket arrangement requires only two pieces and still provides the additional rotational capability in comparison to the four or more pieces of Gregory's swivel means. The ball and socket configuration provides this simplicity by connecting to the case by a snap fit engagement and linking the two pieces together by interference engagement, thus eliminating separate fasteners. The hinge pin embodiment provides multiple tasking by the hinge pin so that the swivel assembly connects to the case via the hinge pin, rotation about the hinge pin is coaxial with the second axis, and rotation of the display case lid and base occurs about the hinge pin to open and close the display case. Applicants' embodiment using a hanging member, a swivel member and a lower member eliminates need for a boss on the display case, provides a simple snap fit engagement between the hanging and swivel members and provides a snap fit engagement between the swivel and lower members with the latter snap fit providing rotation about the second axis. The various snap fit engagements facilitate assembly of the swivel assembly and the connection to the display case. [0010] As noted above, the Gregory swivel means is configured to be unremovable from the display case and does not permit the display case to be removed from the display rack. Applicants' invention, by contrast, provides a swivel assembly with separable elements which permit the display case to be removed from the rod assembly without unlocking the rod assembly from the support structure, such as a peg board. Thus, after a customer has viewed the item of merchandise while still connected to the rod assembly, a store employee may then easily unlock the display case from the rod assembly to allow purchase of the item. One advantage of this configuration is that the item display case may be removed from the rod assembly without separating the rod assembly from the support structure. Another advantage is that the item may remain in the case until immediately prior to purchase at the cash register, thus providing at least a visual indicator to store or security personnel that the item has not yet been purchased. Additionally, an electronic article surveillance tag may be connected to the display case as opposed to the merchandise, so that an alarm may sound while the item is in the case, but not after it is removed from the lockable display case. [0011] Because Gregory does not include the separable elements noted above, the Gregory device does not need a corresponding locking mechanism. Gregory does disclose locking mechanisms for locking the display case, namely a padlock and a lock with a slidable plunger, but these are standard locks operable with a standard key. Applicants' locking mechanism for holding the separable elements together may be magnetically unlockable and invisible to the eye of a potential thief. The invisibility may prevent a thief from even recognizing that there are separable elements. In addition, the same key may be used for the lock used with the separable elements, the lock used to lock the rod assembly to the support structure and the lock used with the end assembly. [0012] Further, the wire rack display and display cabinet of Gregory have several limitations. First, Gregory's wire display rack is bulky and cumbersome even if not attached to the display cabinet. When attached atop the boxlike display cabinet, the display support structure is particularly cumbersome if not stationary and certainly consumes a great deal of space. In addition, the wire rack is configured in a shelf-like fashion whereby the display cases rest upon one or more wires while attached via the swivel means to the rod. [0013] By contrast, Applicants' rod assemblies are simple and compact, and are thus easily manufactured at a relatively low cost and consume far less precious floor space. Applicants' rod assemblies are easily attachable to support structures such as peg boards and are lockable to such structures to prevent the entire rod assembly and merchandise from being rapidly removed. Rod assemblies are provided which either attach at both ends to the support structure (including the U-shaped embodiment) or include an end assembly, each option configured to prevent unauthorized removal of merchandise from the rod assemblies while permitting easy loading of merchandise thereon. In addition, Applicants' rod assemblies are easily movable and are removable from the support structure to allow reuse of the rod assemblies elsewhere and facilitate reorganization upon the support structure as needed. [0014] Gregory's display case uses walls having openings therein to permit a consumer to view printed material on the merchandise stored therein. Gregory's case also provides a partition wall spaced from one of the walls, the partition wall intended to make the case fit a smaller item of merchandise and being removable in a breakaway fashion to allow the case to fit a larger item. Applicants' display case fully encloses an item of merchandise, thus providing better protection from vandalism and accommodating a variety of sizes of items to be displayed therein without the need for such a partition wall. In addition, Applicants' transparent case offers visibility from all sides without concern for creating wall openings, which must be particularly sized to securely retain the merchandise and simultaneously allow visibility of pertinent indicia on the merchandise. BRIEF SUMMARY OF THE INVENTION [0015] The invention generally provides a system for securely displaying merchandise in a manner that allows customers to handle and view the merchandise without removing the merchandise from a display case. The invention provides different interchangeable display configurations that allow a customer to handle, pivot, and rotate a secured item of merchandise. [0016] In one embodiment, the present invention provides a merchandise display system that includes a display structure; a swivel assembly rotatable about a first axis and rotatable about a second axis substantially perpendicular to the first axis; the swivel assembly adapted to be connected to the display structure; and a display case adapted to carry an item of merchandise; the display case being connected to the swivel assembly so that the display case is rotatable about the first and second axes. [0017] In another embodiment, the present invention provides a merchandise display system that includes a display structure; a first member and a swivel member rotatably connected to the first member about a first axis; the first member being adapted to be connected to the display structure; a display case having a pair of members selectively lockable to one another and being adapted to carry an item of merchandise; and at least one hinge pin having a longitudinal second axis substantially perpendicular to the first axis and rotatably connecting the swivel member to the display case about the second axis so that the display case is rotatable about the first and second axes; the at least one hinge pin rotatably connecting the display case members to one another about the second axis whereby the display case members are rotatably movable between open and closed positions when unlocked. [0018] In another embodiment, the present invention provides a merchandise display system having a display structure; a first member, a swivel member and a U-shaped lower member having a pair of legs extending from an intervening base; the swivel member being rotatably connected to the first member about a first axis by a snap fit engagement; the first member being adapted to be connected to the display structure; a display case adapted to carry an item of merchandise; the display case defining a pair of spaced holes on one end thereof and being lockable to selectively retain or release the item of merchandise; and the lower member base being disposed within the display case and the lower member legs respectively extending through the holes in the display case so that the lower member supports the display case and the lower member legs rotatably connect the lower member to the swivel member by a snap fit engagement about a second axis substantially perpendicular to the first axis so that the display case is rotatable about the first and second axes. [0019] The invention also provides an embodiment wherein a display rod is locked at both of its ends to a display structure. The display rod is adapted to carry items of merchandise. [0020] The invention also provides an embodiment wherein a connector is snap fit to a display case in a one-way snap fit connection. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0021] [0021]FIG. 1 is a side elevational view of the first embodiment showing the merchandise display system of the present invention. [0022] [0022]FIG. 2 is a fragmentary exploded perspective view of the first embodiment showing the various members of the hanging assembly and the display case. [0023] [0023]FIG. 3 is a fragmentary perspective view of the first embodiment of the hanging assembly and display case. [0024] [0024]FIG. 4 is a fragmentary partial sectional view of the first embodiment of the hanging assembly and the display case. [0025] [0025]FIG. 5 is a fragmentary perspective view of the first embodiment showing the display case and hanging assembly hanging from the lower rod in a display position. [0026] [0026]FIG. 6 is a fragmentary perspective view of the first embodiment similar to FIG. 5 with the hanging assembly and display case in a partially rotated position. [0027] [0027]FIG. 7 is a fragmentary perspective view of the first embodiment similar to FIGS. 5 and 6 showing the display case and hanging assembly in a further rotated position. [0028] [0028]FIG. 8 is a fragmentary side elevational view of the first embodiment showing the display case rotated upwardly from the display position (shown in phantom lines). [0029] [0029]FIG. 9 is a fragmentary side elevational view of the first embodiment similar to FIG. 8 showing the door of the display case being opened and the merchandise being removed from the display case. [0030] [0030]FIG. 10 is a side elevational view of a second embodiment of the present invention. [0031] [0031]FIG. 11 is a fragmentary exploded view of the second embodiment showing the hanging assembly and display case. [0032] [0032]FIG. 12 is a perspective view of the second embodiment showing the hanging assembly and display case. [0033] [0033]FIG. 13 is a fragmentary partial sectional view of the second embodiment showing the hanging assembly and the display case. [0034] [0034]FIG. 14 is a fragmentary side elevational view of the second embodiment showing a display case rotated upwardly from a display position (shown in phantom lines). [0035] [0035]FIG. 15 is a fragmentary side elevational view of the second embodiment showing the display case in an open position with the item of merchandise being removed therefrom. [0036] [0036]FIG. 16 is a side elevational view of a third embodiment of the present invention. [0037] [0037]FIG. 17 is a fragmentary exploded view of the third embodiment showing the hanging assembly and display case. [0038] [0038]FIG. 18 is a fragmentary perspective view of the third embodiment showing the hanging assembly and display case. [0039] [0039]FIG. 19 is a partial sectional view showing the display case and hanging assembly including a locking device in a locked position. [0040] [0040]FIG. 20 is a side elevational view of the third embodiment including an alternate rod assembly and one display case in a rotated position. [0041] [0041]FIG. 21 is a top plan view of the third embodiment as shown in FIG. 20. [0042] [0042]FIG. 22 is a fragmentary partial sectional view of the third embodiment showing the rod assembly, display case and hanging assembly including a magnetic key and the locking device in an unlocked position. [0043] [0043]FIG. 23 is a fragmentary exploded partial sectional view of the third embodiment as shown in FIG. 22 wherein the locking device is unlocked and in a released position. [0044] [0044]FIG. 24 is a side elevational view of a fourth embodiment of the present invention. [0045] [0045]FIG. 25 is a fragmentary exploded perspective view of the fourth embodiment showing the hanging assembly and display case. [0046] [0046]FIG. 26 is a fragmentary partially exploded perspective view of the fourth embodiment showing the hanging mechanism intact and showing how the locking tabs of the mechanism insert into the slots in the display case. [0047] [0047]FIG. 27 is a partial sectional view of the fourth embodiment as viewed from the side showing the hanging assembly in a position prior to being inserted into the slots in the display case. [0048] [0048]FIG. 28 is a view similar to FIG. 27 with the hanging assembly connected to the display case. [0049] [0049]FIG. 29 is a fragmentary perspective view similar to FIG. 26 showing the hanging assembly connected to the display case. [0050] [0050]FIG. 30 is a fragmentary partial sectional view of the fourth embodiment taken on line 30 - 30 of FIG. 28. [0051] Similar numbers refer to similar parts throughout the specification. DETAILED DESCRIPTION OF THE INVENTION [0052] A first embodiment of the merchandise display system of the present invention is indicated generally at 100 and is shown in FIGS. 1-9. Display system 100 includes a lockable rod assembly 102 , a hanging assembly 104 which hangs from rod assembly 102 and a lockable merchandise display case 106 which is connected to and hangs from hanging assembly 104 . Hanging assembly 104 is configured to allow display case 106 and merchandise 122 within to pivot and swivel in a manner such that the consumer can easily handle case 106 and view merchandise 122 within case 106 . [0053] Lockable rod assembly 102 includes an inner end 108 which is lockable to a peg board 110 or the like. Inner end 108 may also be securely fixed to a wall or other type of display unit. Rod assembly 102 includes lockable base assembly 109 adjacent inner end 108 . Rod assembly 102 further includes an upper rod 112 and a lower rod 114 which are substantially parallel and extend outwardly and horizontally from inner end 108 to an outer end 116 . Inner rod assembly 102 further includes a locking mechanism 118 adjacent outer end 116 , the locking mechanism locking onto rod 114 to prevent removal of merchandise from lower rod 114 . One embodiment of a rod assembly that may be used is more fully described in U.S. Pat. No. 6,474,478 granted to Huehner et al. on Nov. 5, 2002, and said patent is incorporated herein by reference. [0054] Display case 106 includes an interior chamber 120 in which is inserted an item of merchandise 122 . Display case 106 includes a front side 119 , a back side 121 , and a pair of lateral sides 123 . Display case 106 further includes an upper end 124 and a lower end 126 . A lockable door 128 is hingedly connected to case 106 by hinge 130 adjacent lower end 126 . Case 106 also includes an upper wall 132 adjacent upper end 124 in opposed relation to door 128 . Upper wall 132 defines a pair of slots 134 for receiving a portion of hanging assembly 104 as described below. Any of a variety of known lockable cases may be used as display case 106 . [0055] In accordance with the present invention, hanging assembly 104 includes a hanging member 136 , a swivel member 138 , a U-shaped lower member 140 and a cap 142 . Hanging member 136 has an upper portion 144 which defines a hole 146 for receiving lower rod 114 . Hanging member 136 further includes a lower portion 148 which includes a pair of downwardly extending spaced prongs 150 each of which includes a neck 152 , a shoulder 154 extending outwardly from neck 152 and a surface 156 which tapers downwardly and inwardly from shoulder 154 . [0056] Swivel member 138 defines a vertical hole 158 for receiving prongs 150 of hanging member 136 . Swivel member 158 further includes shoulders 160 (FIG. 4) which separate a cylindrical upper chamber 162 and a cylindrical lower chamber 164 of hole 158 , the upper chamber having a smaller diameter than the lower chamber. Hole 158 is configured to receive prongs 150 of hanging member 136 such that shoulders 160 and shoulders 154 engage one another in a snap fit engagement which prevents removal of hanging member 136 from swivel member 138 . Tapered surfaces 156 facilitate in section of prongs 150 into hole 158 . Cap 142 covers lower chamber 164 of hole 158 and may do so by snap fit engagement or be secured in another manner known in the art. Swivel member 138 has ends 166 , from each of which extend downwardly an inner tab 168 and an outer tab 170 opposed to one another in spaced relation to define a slot 172 . Outer tab 170 defines a horizontal hole 173 . [0057] U-shaped lower member 140 includes a substantially flat and rectangular base member 174 from which extend upwardly a pair of spaced tabs 176 in opposed relation to one another. Each tab 176 has an outer surface 178 from which extends a dome-shaped knob 180 . Base member 174 of lower member 140 is configured to be positioned in interior chamber 120 of display case 106 adjacent upper wall 132 to provide the connection of member 174 to case 106 . Tabs 176 of member 140 extend through slots 134 in upper wall 132 of display case 106 and into slots 172 of swivel member 138 . Knobs 180 slide into respective holes 173 in outer tabs 170 to form a snap fit engagement. An axis 182 extends vertically through hole 158 of swivel member 138 and also between prongs 150 of hanging member 136 . An axis 184 passes through knobs 180 , as shown in FIG. 8. [0058] In operation, hanging assembly 104 allows display case 106 to be maneuvered easily in a great variety of positions so that a consumer can easily view all sides of merchandise 122 encased therein. FIGS. 5-9 indicate the various positions of the case and show its maneuverability and overall use. As seen in FIG. 5, hanging assembly 104 is in a display position as it ordinarily would be for display purposes as it hangs from lower rod 114 of rod assembly 102 . In this position, swivel member 138 and display case 106 are situated substantially normal to lower rod 114 as viewed from above. FIG. 6 shows hanging assembly 104 along with display case 106 in a position rotated approximately 90° from the position shown in FIG. 5 about axis 182 . In this position, swivel member 138 and display case 106 are situated substantially parallel to lower rod 114 as viewed from above. Swivel member 138 swivels about axis 182 as supported by shoulders 160 resting on shoulders 154 of prongs 150 . The diameter of upper chamber 162 of hole 158 is large enough to allow chamber 162 to rotate about neck 154 of prongs 150 while the diameter of lower chamber 164 likewise allows rotation about tapered surfaces 156 of prong 150 . Cap 142 functions to prevent tampering with prongs 150 by a shoplifter attempting to break prongs 150 or disengage them from within hole 158 . The display position of FIG. 5 shows upper wall 132 , front side 119 and lateral sides 123 . FIG. 6, like FIG. 5, continues to show upper wall 132 and the same lateral side 123 , but in the 90° swivelled position also shows back side 121 of case 106 . [0059] [0059]FIG. 7 shows hanging assembly 104 and display case 106 rotated approximately 180° from the display position shown in FIG. 5. Thus, FIG. 7 shows back side 121 and upper wall 132 along with the other lateral side 123 of display case 106 . The rotational movement of swivel member 138 allows swivel member 138 and display case 106 to rotate 360° about axis 182 , thereby allowing all sides of display case 106 and merchandise 122 encased therein to be seen by consumers. Because a plurality of items of merchandise 122 are displayed within respective cases 106 hanging from lower rod 114 , ordinarily the simple rotational movement allowed by swivel member 138 may not be sufficient to allow a consumer to view all the sides easily due to interference of such movement by the other cases 106 . This difficulty is resolved by the additional ability of hanging assembly 104 to pivot upwardly as shown in FIG. 8. [0060] More particularly, lower member 140 is configured to rotate about axis 184 which passes through knobs 180 . Tabs 176 of lower member 140 move freely within slots 172 defined by swivel member 138 and knobs 180 move freely within respective holes 173 . However, the snap fit engagement of knobs 180 into holes 173 is sufficiently secure to prevent removal by a shoplifter or make such removal rather difficult. The rotational motion about axis 184 allows display case 106 to travel an arc of at least 180° in the direction between inner end 108 and outer end 116 of rod assembly 102 , limited only by interference with lower rod 114 , locking mechanism 118 , base assembly 109 , peg board 110 , or any other display cases 106 hanging from rod 114 . Referring back to the position shown in FIG. 6, the rotational motion indicated in FIG. 8 from the position shown in FIG. 6 would allow case 106 to be moved in a far broader arc approaching that of a full circle, limited only by the interference with upper rod 112 and other such members. The overall movement allowed by the rotation about axes 182 and 184 allows display case 106 to be maneuvered in nearly any position so that item of merchandise 122 can be easily viewed and relevant information read from all sides of said item. The overall movement of display case 106 is also facilitated and enhanced by the fact that hanging assembly 104 is able to rotate about lower rod 114 . FIG. 9 shows display case 106 rotated upwardly towards outer end 116 of rod assembly 102 . Further, lockable door 128 is shown in an open position after rotating about hinge 130 . Finally, item of merchandise 122 is shown being removed from case 106 . [0061] Thus, merchandise display system 100 provides a secure system by which items of merchandise 122 are encased in display cases 106 which have lockable doors 128 to prevent merchandise 122 from being removed without authorization. Further, system 100 prevents unauthorized removal from lower rod 114 of hanging assembly 104 and display case 106 hanging therefrom. System 100 also allows the consumer to maneuver display case 106 with item of merchandise 122 therein to easily view merchandise 122 without the need for removal from rod 114 . Thus, system 100 provides security for the seller as well as convenient review of merchandise 122 for the consumer. [0062] A second embodiment of the merchandise display system of the present invention is indicated generally at 200 and is shown in FIGS. 10-15. Display system 200 includes a lockable rod assembly 202 , a hanging assembly 204 which hangs from rod assembly 202 and a lockable merchandise display case 206 which is connected to and hangs from hanging assembly 204 . Hanging assembly 204 is configured to allow display case 206 and merchandise 222 within to pivot and swivel in a manner such that the consumer can easily handle case 206 and view merchandise 222 within case 206 . [0063] Lockable rod assembly 202 includes an inner end 208 which is lockable to a peg board 210 or the like. Rod assembly 202 includes lockable base assembly 209 adjacent inner end 208 . Rod assembly 202 further includes an upper rod 212 and a lower rod 214 which are substantially parallel and extend outwardly and horizontally from inner end 208 to an outer end 216 . Inner rod assembly 202 further includes a locking mechanism 218 adjacent outer end 216 , the locking mechanism locking onto rod 214 to prevent removal of merchandise from lower rod 214 . Rod assembly 202 is more fully described in U.S. Pat. No. 6,474,478, as noted above. [0064] Display case 206 includes an interior chamber 220 in which is inserted an item of merchandise 222 . Display case 206 includes a front side 219 , a back side 221 , and a pair of lateral sides 223 . Display case 206 further includes an upper end 224 and a lower end 226 . Unlike display case 106 , display case 206 does not have a lockable door adjacent the lower end. Instead, display case 206 includes an inner shell 228 and an outer shell 229 which rotate about a pair of common hinge pins 230 (FIG. 11) between a closed position (FIG. 14) and an open position (FIG. 15), the inner shell and outer shell being lockable in the closed position. [0065] In accordance with the present invention, hanging assembly 204 includes a hanging member 236 , a swivel member 238 , hinge pins 230 and a cap 242 . Hanging member 236 has an upper portion 244 which defines a hole 246 for receiving lower rod 214 . Hanging member 236 further includes a lower portion 248 which includes a pair of downwardly extending prongs 250 each of which includes a neck 252 , a shoulder 254 extending outwardly from neck 252 and a surface 256 which tapers downwardly and inwardly from shoulder 254 . [0066] Swivel member 238 defines a vertical hole 258 for receiving prongs 250 of hanging member 236 . Swivel member 258 further includes shoulders 260 (FIG. 13) which separate a cylindrical upper chamber 262 and a cylindrical lower chamber 264 of hole 258 , the upper chamber having a smaller diameter than the lower chamber. Hole 258 is configured to receive prongs 250 of hanging member 236 such that shoulders 260 and shoulders 254 engage one another in a snap fit engagement which prevents removal of hanging member 236 from swivel member 238 . Tapered surface 256 facilitates in section of prongs 150 into hole 258 . Cap 242 covers lower chamber 264 of hole 258 and may do so by snap fit engagement or be secured in another manner known in the art. Swivel member 238 has ends 266 and a pair of arms 268 extending downwardly adjacent respective ends 166 . Arms 268 define a pair of respective horizontal holes 273 which are substantially in alignment with one another and also configured to align with hinge holes 231 formed in inner shell 228 and hinge holes 233 formed in outer shell 229 of display case 206 . Hinge pins 230 are inserted in hinge holes 231 and 233 and into hole 273 in arms 268 , thereby allowing for rotational movement about axis 235 (FIG. 13), which extends through hinge pins 230 . This rotational movement may be accomplished, for example, by the diameters of hinge holes 233 of outer shell 229 forming a snug fit with hinge pins 230 while hinge holes 231 of inner shell 228 and holes 273 of arms 268 are large enough to permit a rotational movement of hinge pins 230 . [0067] In operation, hanging assembly 204 allows display case 206 to be maneuvered easily in a great variety of positions so that a consumer can easily view all sides of merchandise 222 encased therein. FIGS. 5-7 showing the first embodiment of the present invention are generally applicable as to the movement of the second embodiment as well, and in combination with FIGS. 14-15, indicate the various positions of the case and show its maneuverability and overall use. Hanging assembly 204 functions in the same manner as hanging assembly 104 in regard to the rotational or swiveling properties as viewed from above, as described in regard to assembly 104 above. [0068] Like assembly 104 , hanging assembly 204 pivots upwardly as shown in FIG. 14. While the same motion is allowed, assembly 204 utilizes a different configuration to achieve that effect. More particularly, with hinge pins 230 inserted into hinge holes 231 and 233 of display case 206 and holes 273 of arms 268 , display case 206 is able to rotate about axis 235 with respect to swivel member 238 . The maneuverability of display case 206 about axis 235 is essentially the same as display case 106 about axis 184 . Further, the overall maneuverability of display case 206 is substantially the same as that of case 106 , as described above. [0069] [0069]FIG. 15 shows display case 206 rotated upwardly towards outer end 216 of rod assembly 202 . FIG. 15 also shows display case 206 in an open position. Display case 206 differs from case 106 in that display case 206 includes an inner shell 228 and an outer shell 229 that pivot with respect to one another about axis 235 with the use of hinge pins 230 . FIG. 15 further shows item of merchandise 222 being removed from case 206 . Inner shell 228 and outer shell 229 may be locked to one another in a closed position (FIG. 14) to prevent unauthorized removal of merchandise 222 . [0070] Thus, merchandise display system 200 provides a secure system by which items of merchandise 222 are encased in display cases 206 which have lockable inner and outer shells 228 and 229 to prevent merchandise 222 from being removed without authorization. Further, system 200 prevents unauthorized removal from lower rod 214 of hanging assembly 204 and display case 206 hanging therefrom. System 200 also allows the consumer to maneuver display case 206 with item of merchandise 222 therein to easily view merchandise 222 without the need for removal from rod 214 . Thus, system 200 provides security for the seller as well as convenient review of merchandise 222 for the consumer. [0071] A third embodiment of the merchandise display system of the present invention is indicated generally at 300 and is shown in FIGS. 16-23. Display system 300 includes a lockable rod assembly 302 , a hanging assembly 304 which hangs from rod assembly 302 and a lockable merchandise display case 306 which is connected to and hangs from hanging assembly 304 . Hanging assembly 304 is configured to allow display case 306 and merchandise 322 within to pivot and swivel in a manner such that the consumer can easily handle case 306 and view merchandise 322 within case 306 . [0072] Lockable rod assembly 302 includes an inner end 308 which is lockable to a peg board 310 or the like. Rod assembly 302 includes lockable base assembly 309 adjacent inner end 308 . Rod assembly 302 further includes an upper rod 312 and a lower rod 314 which are substantially parallel and extend outwardly and horizontally from inner end 308 to an outer end 316 . Inner rod assembly 302 further includes a locking mechanism 318 adjacent outer end 316 , the locking mechanism locking onto rod 314 to prevent removal of merchandise 322 from lower rod 314 . Rod assembly 302 is the same as assemblies 102 and 202 . [0073] Display case 306 includes an interior chamber 320 in which is inserted an item of merchandise 322 . Display case 306 includes a front side 319 , a back side 321 , and a pair of lateral sides 323 . Display case 306 further includes an upper end 324 and a lower end 326 . A lockable door 328 is hingedly connected to case 306 by hinge 330 . Case 306 also includes an upper wall 332 adjacent upper end 324 in opposed relation to door 328 . Upper wall 332 defines a pair of slots 334 for receiving a portion of hanging assembly 304 as described below. [0074] In accordance with the present invention, hanging assembly 304 includes a hanging member 336 , a swivel member 338 , a U-shaped lower member 340 and a cap 342 . Hanging assembly 304 allows case 306 to be removed from rod assembly 302 when a lock is unlocked. The key that unlocks this lock may be the same key that unlocks rod assembly 302 . Hanging member 336 includes an upper member 341 and a lower member 343 . Upper member 341 of hanging member 336 has an upper portion 344 which defines a hole 346 for receiving lower rod 314 . A cylinder 345 defining an interior chamber 347 (FIG. 22) extends downwardly from upper portion 344 of upper member 341 . Cylinder 345 has a lower end 337 and defines an annular recessed area 339 adjacent lower end 337 . Recessed area 339 is part of interior chamber 347 . Lower member 343 includes a lower portion 348 and a generally cylindrical rod 349 extending upwardly therefrom. Rod 349 defines a notch 351 extending lengthwise on one side of rod 349 . An annular flange 357 complementary to recessed area 339 extends radially outward from rod 349 below notch 351 . A plate spring 353 is disposed within interior chamber 347 of cylinder 345 to one side of chamber 347 . In an assembled form, rod 349 of lower member 343 is disposed within interior chamber 347 of cylinder 345 with annular flange 357 disposed within recessed area 339 in a snap-fit engagement. In a locked position (FIG. 19), plate spring 353 is partially disposed within notch 351 and engages an upper portion of rod 349 . FIG. 22 shows hanging assembly 304 in an unlocked position wherein a magnetic key 355 attracts the portion of plate spring 353 which was disposed within notch 351 in the locked position so that plate spring 353 lies flat outside the bounds of notch 351 . [0075] Swivel member 338 , cap 342 and U-shaped lower member 340 are identical to their counterparts in the first embodiment as described above. However, in accordance with the present invention, FIGS. 20 and 21 show an alternate embodiment of a lockable rod assembly 303 . Rod assembly 303 includes a pair of ends 305 which may be fixed to a display or which can be locked in a lockable base assembly 307 connected to a peg board 309 or the like. At least one base assembly 307 is configured to allow upper portions 344 to be placed on the rod when assembly 307 is unlocked. [0076] In operation, hanging assembly 304 functions in the same manner as hanging assembly 104 of the first embodiment, except for the removably connected upper and lower members 341 and 343 of hanging member 336 and the locking mechanism created by upper member 341 , lower member 343 and plate spring 353 . In addition, the maneuverability of display system 300 is altered somewhat by the use of the alternate U-shaped lockable rod assembly 303 , as described below. [0077] When rod 349 is disposed in interior chamber 347 with flange 357 forming a snap-fit engagement with recessed area 339 , flange 357 supports the lower portions of hanging assembly 304 along with display case 306 and merchandise 322 . However, this snap-fit engagement still allows reasonably easy removal of rod 349 from interior chamber 347 when hanging assembly 304 is in the unlocked position. [0078] The locking mechanism of hanging member 336 functions as follows. Rod 349 is inserted into interior chamber 347 of cylinder 345 so that the inwardly extending portion of plate spring 353 is depressed outwardly until notch 351 aligns with said portion of plate spring 353 , thereby allowing said portion of plate spring 353 to move inwardly into notch 351 and engage an upper portion of rod 349 , to prevent removal of rod 349 from interior chamber 347 of cylinder 345 . To unlock the locking mechanism, magnetic key 355 is placed against cylinder 345 adjacent plate spring 353 to attract the inwardly disposed portion of plate spring 353 , thus removing said portion of plate spring 353 from within notch 351 , as shown in FIG. 22. Rod 349 may be removed from interior chamber 347 , as shown in FIG. 23. This allows the lower portion of hanging assembly 304 to be removed along with display case 306 and item of merchandise 322 as desired. This gives an alternative method of removing display case 306 from rod 314 or rod assembly 303 without having to unlock the rod assembly itself. [0079] As viewed from above, U-shaped lockable rod assembly 303 allows for similar movement as with rod assembly 302 , which as noted above, is the same as assemblies 102 and 202 . However, the maneuverability of display case 306 hanging from rod assembly 303 is not limited by an upper rod or a locking mechanism at the end of an upper and lower rod as is the case with rod assembly 302 . Similar to rod assembly 302 , assembly 303 would be limited by any additional display cases 306 hanging from rod assembly 303 . However, maneuverability would also be limited by a peg board 309 or the like. Nonetheless, display case 306 is able to rotate in a 360° arc as viewed from above and also may rotate about axis 384 such that it may travel an arc of at least 180° in a direction between a pair of ends 305 of rod assembly 303 . [0080] Thus, merchandise display system 300 provides a secure system by which items of merchandise 322 are encased in display cases 306 which have lockable doors 328 to prevent merchandise 322 from being removed without authorization. Further, system 300 prevents unauthorized removal from lower rod 314 of hanging assembly 304 and display case 306 hanging therefrom. Assembly 300 also allows the consumer to maneuver display case 306 with item of merchandise 322 therein to easily view merchandise 322 without the need for removal from rod 314 . Thus, system 300 provides security for the seller as well as convenient review of merchandise 322 for the consumer. [0081] A fourth embodiment of the merchandise display system of the present invention is indicated generally at 400 and is shown in FIGS. 24-30. Display system 400 includes a lockable rod assembly 402 , a hanging assembly 404 which hangs from rod assembly 402 and a lockable merchandise display case 406 which is connected to and hangs from hanging assembly 404 . Hanging assembly 404 is configured to allow display case 406 and merchandise 422 within to pivot and swivel in a manner such that the consumer can easily handle case 406 and view merchandise 422 within case 406 . [0082] Lockable rod assembly 402 is the same as rod assembly 102 and functions in the same manner. In addition, display case 406 is similar to display case 106 except that upper wall 432 , instead of defining a pair of slots, defines a pair of holes 434 . As viewed from above, holes 434 are substantially shaped like a cross-section of a light bulb wherein there is a circular portion 433 with a U-shaped portion 435 extending outwardly therefrom. [0083] In accordance with the present invention, hanging assembly 404 includes a hanging member 436 and a swivel member 438 . Hanging member 436 has an upper portion 444 which defines a hole 446 for receiving lower rod 414 . Upper portion 444 also includes a pair of ears 445 extending outwardly therefrom. Hanging member 436 further includes a lower portion 448 which includes a downwardly extending neck 452 from which extends downwardly a spherical member 450 . [0084] Swivel member 438 defines a vertical cylindrical hole 458 for receiving spherical member 450 of hanging member 446 . Hole 458 is bounded by cylinder 447 having an upper end 449 and a lower end 451 . Hole 458 is narrowed adjacent upper end 449 of cylinder 447 by inwardly extending annular flange 453 . A pair of wings 455 extend horizontally outwardly from cylinder 447 adjacent lower end 451 . A pair of ribs 457 extend outwardly in a vertical plane from cylinder 447 and upwardly from respective wings 455 . A pair of spaced locking tabs 459 extend downwardly from respective wings 455 . As shown in FIGS. 26-28, each locking tab includes a neck 461 extending downwardly from respective wing 455 and a substantially circular foot 463 connected to neck 461 there below. In relation to neck 461 , foot 463 extends toward front side 419 of display case 406 when swivel member 438 is connected thereto, and foot 463 also extends laterally toward lateral sides 423 of case 406 . Each locking tab 459 also includes a finger which extends downwardly from respective wing 455 and outwardly from respective neck 461 away from the forward extension of foot 463 such that finger 465 extends toward back side 421 of display case 406 when swivel member 438 is installed thereon. [0085] In assembling hanging assembly 404 , upper portion 444 of hanging member 436 is inserted upwardly through hole 458 of swivel member 438 so that upper portion 444 is disposed above cylinder 447 and spherical member 450 rests against annular flange 453 . The distance defined by the outermost portions of ears 445 is larger than the diameter defined by the innermost portion of annular flange 453 . Ears 455 nonetheless slide past flange 453 so that during assembly ears 445 prevent hanging member 436 from slipping back through hole 458 before hanging member 436 is hung on lower rod 414 of rod assembly 402 . The diameter of spherical member 450 is wide enough to prevent spherical member 450 from being pushed upwardly beyond annular flange 453 , but is small enough to allow easy movement within hole 458 of cylinder 447 . [0086] Locking tabs 459 form a locking engagement with display case 406 when inserted properly into holes 434 . FIGS. 26-28 indicate how locking tabs 459 are inserted into holes 434 . First, each foot 463 is aligned with and inserted into a respective circular portion 433 of hole 434 . Each foot 463 is then slid toward front side 419 of case 406 so that each neck 461 fits into a respective U-shaped portion 435 . Simultaneously, each finger 465 slides along upper wall 432 until it snaps downwardly into a respective circular portion 433 of hole 434 . Once in this configuration, as shown in FIG. 28, locking tabs 459 form a locking engagement with case 406 . [0087] In operation, hanging assembly 404 allows display case 406 to be maneuvered easily in a great variety of positions so that a consumer can easily view all sides of merchandise 422 encased therein. Hanging assembly 104 functions somewhat similarly to the previous embodiments in that it allows for substantially the same type of movement. Particularly, assembly 404 and case 406 may be rotated 360° about vertical axis 482 . In addition, the ball and socket configuration of assembly 404 allows swivel member 438 and display case 406 to pivot upwardly in any direction from axis 482 . While this upward movement is multi-directional, it is more limited than in the previous embodiments. The limiting factor is an interference between annular flange 453 or upper end 449 of cylinder 447 and neck 452 of hanging member 436 as swivel member 438 and display case 406 are moved in an upward direction. Nonetheless, with the additional mobility provided by rotational movement of hanging member 436 about lower rod 414 , display case 406 may be maneuvered sufficiently to view any side of display case 406 without difficulty. [0088] Thus, merchandise display system 400 provides a secure system by which items of merchandise 422 are encased in display cases 406 which have lockable doors 428 to prevent merchandise 422 from being removed without authorization. Further, system 400 prevents unauthorized removal from lower rod 414 of hanging assembly 404 and display case 406 hanging therefrom. System 400 also allows the consumer to maneuver display case 406 with item of merchandise 422 therein to easily view merchandise 422 without the need for removal from rod 414 . Thus, system 400 provides security for the seller as well as convenient review of merchandise 422 for the consumer. [0089] In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. [0090] Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.

A merchandise display system includes a rod lockably connected to a peg board, a hanging member hanging from the rod and a swivel member rotatably connected to the hanging member about a first axis. The swivel member is connected to a lockable display case for carrying an item of merchandise and is rotatable about a second axis perpendicular to the first axis. Thus, the display case is rotatable about the first and second axes to facilitate viewing the merchandise from any angle while the case is lockably connected to the rod. The hanging and swivel members may be a ball and socket combination. Alternately, the swivel member may connect to the display case via a hinge pin about which portions of the case may rotate to open and close. Alternately, a lower member may extend from within the case through holes therein to rotatably connect to the swivel member about the second axis.

CROSS REFERENCE TO REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Patent Application 62/253,681 entitled “Post-Tensioning Apparatus and System for Structures” filed on Nov. 11, 2015, the entire contents of which are incorporated herein by reference in its entirety for all purposes. FIELD OF THE INVENTION [0002] The present invention pertains in general to post-tensioning apparatus and systems surrounding the fabrication and repair of concrete and other construction materials. The present invention surrounds apparatus and system directed to the post-tensioning for reinforcement of existing and new concrete structures through the application of tensile forces between two attachment points anchored to the structure to be mended. BACKGROUND OF THE INVENTION [0003] The field of concrete installation and maintenance, particularly surrounding structural or load bearing concrete, requires site preparation and formula of mix to create the desired preparation. Although mechanically strong in compression, concrete is relatively weak in tensile and bending loads and is subject to cracking and breakage under such conditions. [0004] Practices including techniques of post-tensioning, which involves the pre-stressing of steel tendons within the concrete form to account for its relative weakness in tension. This practice is often used in installation for purposes such as commercial and residential construction where beams, floors and bridging components must span a length exceeding longer than practical with ordinary reinforced concrete. [0005] Although the practice of post-tensioning aims to pre-load concrete and place it under a resting compressive load to counteract tensile and bending loads to mitigate mechanical failures. However, uncontrollable variables such as frost heaving, ground movement, erosion, water infiltration and others compromise the structural integrity of concrete and can cause cracking and mechanical failure of the structure of the concrete installation. [0006] Due to the costly or nature or logistical impossibility of the replacement of concrete installations, many solutions aim to repair concrete after mechanical failure. Although it may seem sensible to replace a concrete installation in some situations, it will be appreciated that even the wholesale demolition and reinstallation of the concrete may not guarantee against failure in the future. [0007] Cracks in concrete are caused due to the mechanical failure of the concrete in a localized area due to a possible variety of problems with the installation. For this reason, tensioning may be desired in scenarios such as the cross-linking of independently poured concrete installations or providing tension in “post-tensioning” to repair a concrete installation using tensile strengthening features. The application of metal structure for the tensile reinforcement is typically placed across a mechanical failure zone such as a fissure or crack where the concrete installation has mechanically failed. Post-tensioning typically involves preloading of a metal structure prior to adding more concrete to reinforce the repair. SUMMARY OF THE INVENTION [0008] Some solutions aim to fill the crack with a bonding adhesive or cement to repair the concrete. However, the lack of strength afforded by cements, often referred to as hydraulic cement, proves problematic. When considering the structural integrity of a concrete installation, the cost of repeated failure depends upon the application of the concrete. And cement patches have a high risk of repeated failure due to weak bond and structural integrity of the cement. [0009] Other solutions to the mechanical failure of concrete resulting in cracks is addressed through internal metal stitching as proposed by U.S. Pat. No. 5,476,340, ('340), and U.S. Pat. No. 5,771,557, ('557), incorporated herein by reference, to Contrasto. Constrasto '340 discloses a method surrounding the use of apparatus '557 to bridge a crack using a series of cuts across a crack, inserting metal structure, and making additional cuts across the previous cuts and metal structure to add cross structure in the form of metal brackets prior to the addition of filler material. Contrasto '340 fails to provide any method of tension application to the concrete. [0010] Constrasto '557 aims to provide increased localized tensile strength for the concrete around a crack. The higher ductility of steel as compared to concrete does not prevent the movement of the concrete beyond a failure threshold and therefore cannot prevent further cracking in the localized region and Contrastro '557 fails to provide the ability to pre-tension the structure or provide post-tensioning to the concrete structure. [0011] Some solutions aim to address failed concrete by placing devices across cracks due to mechanical failure in efforts to provide post-tensioning by preloading metal members spanning across the crack. These metal members comprise plates with a post at either distal end affixed to one side that are inserted into pre-drilled apertures for anchoring. The metal members are then tensioned using wedge or cam based mechanisms to tension the metal member after the posts have been inserted into the concrete. These tensioning mechanisms, however, are limited in travel. If the apertures created for the posts are spaced too far apart, the user may not be able to install the metal member. If the apertures created for the posts are too close together, the user may not be able to tension the metal member as prescribed. [0012] The present invention relates to a post-tensioning apparatus and system providing functionality of post-tensioning to existing structures. The present disclosure relates to the repair of concrete structures but is not limited to such application. Embodiments of the invention permit the application and adjustment of a modular post-tensioning apparatus including at least two attachment features interconnected by at least one tensioning mechanism. The modularity of the apparatus surrounds the ability to select and use different attachment features based upon the location, substrate, desired tensioning properties and other relevant variables in the tensioning of a structure. [0013] In certain embodiments of the present invention, a modular apparatus and system provides tension to existing structures, such as an existing concrete installation, where it is desired to provide post structural reinforcement. [0014] Embodiments of the apparatus provide tensile strength across a mechanical failure zone without further tensioning of the apparatus. However, tensioning the apparatus preloads the apparatus to resolve tolerances or gaps between the apparatus and the points of application within a structure to which it is applied. Tensioning the apparatus also places the apparatus in tension and compresses the structure between attachment features applied to the structure. This also mitigates tensile forces bearing on the concrete, as concrete is typically weaker in tension than in compression. [0000] Certain embodiments of the present invention comprise at least two tension application components interconnected by one tensioning mechanism. Once the tension application components are applied to the structure, the tensioning mechanism is actuated to apply a tensile load to the tension application components, placing the apparatus in a tensile state. [0015] Tension application components translate forces from the tensioning mechanism to the structure by attaching to the structure, such as a concrete installation. Each tension application component may also be attached to one or more application points. These application points may be on a singular structure or spanning two separate structures. It will be appreciated that the tension application components may comprise a variety of forms including, but not limited to, a post-like device, hook, loop and/or plate with attachment features for attachment to a structure. In certain embodiments, the apparatus permits modular use of a variety of tension application components where the apparatus may be used with two tension application devices of similar or dissimilar size, shape or form. It will be further appreciated that application points may comprise apertures in the structure, other features within the concrete or hardware pre-affixed to the concrete. [0016] In certain embodiments, a tensioning mechanism comprising two axially aligned threaded female features, one having standard clockwise threading and the opposing exhibiting counter-clockwise threading, is referred to as a turnbuckle. In such an embodiment, the tension application components have a cylindrical cross-section with a length of screw threading at a proximal end to engage with the threaded female features of the tensioning mechanism. Furthermore, the distal section of the tension application component has as bend, which provides a post-like form to allow the application of force upon an existing structure. A structure may also be prepared by creating an aperture in the structure where one can place the tension application component to apply force on the structure. [0017] It will be appreciated that a tensioning mechanism may comprise a turnbuckle. The tensioning mechanism may also comprise a rotational device with a set of indexed features radially around the rotational device in which a pawl, cog, or tooth engages to allow motion in one direction only, such as a ratchet, or a geared mechanism such as a rack-and-pinion or worm gear. [0018] Certain embodiments of the present invention are directed to the repair of a concrete structure where a fissure or crack has occurred. The surface is prepared by creating plurality of apertures with at least one aperture being on a first side of a fissure or crack, and at least one aperture being on a second side of a fissure or crack. The apertures are positioned at a distance that generally corresponds to the length of the apparatus prior to actuation of the tensioning mechanism which shortens the apparatus. The distal ends of first and second tension application components are then inserted into the corresponding apertures of the prepared surface. Tension can then be applied by actuating the tensioning mechanism, creating post-tensioning in the area surrounding the crack or fissure. [0019] In certain embodiments, a tension application component is used to apply a tensile load across a portion of a structure. The tension application component comprises an attachment end configured to engage with a tensioning mechanism. The attachment end engages the tensioning mechanism at a proximal end of the tensioning application component. The distal end of the tension application component has a feature such as an aperture or hook-form configured to engage with features installed in the structure. Such features which include, but are not limited to a post or rebar affixed to the structure. [0020] Certain embodiments of the present invention comprise a tensioning application component that engages with the tensioning mechanism. The proximal end of the tension application component has an attachment feature configured to engage with the tensioning mechanism. The distal end of the tension application component is configured to engage the apertures within a prepared surface or extents of an existing structure with a plurality of post-like features. Having a plurality of post-like features distributes the load of the tensioning apparatus across a larger area. The distribution of forces allows the installation of a post-tensioning apparatus with structures having limited structural stability rather than an apparatus with a more concentrated loading which may risk further damage to the structure to be repaired. A scenario in which a user may want to use more than one post-tensioning apparatus, the plurality of post-like features allows the use of fewer post-tensioning apparatuses over a given length of a fissure or crack to achieve stronger structural stability. [0021] Certain embodiments have a tension application component. In certain embodiments, the tension application component comprises a plate-form. The plate-form affixes to a structure to apply tensile load to the structure at the desired location. The plate-form can be affixed by welding or using at least one threaded fastener, masonry anchor or other methods known to those skilled in the art. The plate-form may further comprise a fixation point such as a loop or hook to allow the engagement of a tension application component. It may be desired to affix the plate-form to the structure using a plurality of fasteners or anchors to distribute tensile loading across a larger area of concentration on the structure. This distributed loading can also provide tensile strength between independent structures where other types of tension application components cannot. In contrast, post-like forms create a higher localized concentration of stress. Furthermore, the use of plate-forms may allow the post-tensioning between adjacent structures that are not coplanar such as adjacent planar structures disposed at not offer the necessary structural stability to provide tension between independent structures. [0022] In certain embodiments, a tension application component has a plate-form having at least one aperture. The tension application component includes an engagement feature extending outward from the surface of the plate-form. The engagement features can engage with a tensioning mechanism, including through the use of a threaded male component, the threaded male component typically being axially parallel to the bore of the aperture in the plate-form. In such an embodiment, a tension application component can be attached to a first surface at an angle, typically orthogonal, and attached to a second surface. This allows post-tensioning across a crack or fissured that has occurred proximal to a corner where two sections of a structure meet at an angle. [0023] Certain embodiments of the present invention comprise a tension application component having at least two parallel post structures. The two parallel post structures are disposed at an angle from a connecting body. The tension application component has an aperture, located medial to the post structures. The aperture is also typically axially parallel to the post structures. The tension application component distributes the load applied to the structure and provides a post-tensioning effect to a larger area. In certain embodiments, the tension application component has a post feature attached to a tensioning mechanism, where the post feature is disposed through the medially located aperture. [0024] In certain embodiments of the invention, the apparatus comprises a tensioning mechanism having a consistent cross-sectional profile. The tensioning mechanism can have female threaded features at its distal ends. The threaded receptacles have opposing threading direction. Thus, when engaged with rotationally constrained male threaded features, the opposite threading direction allows both male threaded features to be drawn toward the center of the tensioning mechanism when rotated in a first direction and forces the male threaded features away from center when rotated a second direction, opposite the first direction. Alternatively, it will be appreciated that the tensioning mechanism may have male threaded features and the tension application components have female threaded features. [0025] In certain embodiments, the tensioning mechanism has a torque application feature. The torque application feature actuates the tensioning mechanism by applying rotational forces to tension application components. The torque application feature may have different individual forms or a combination of forms as known to those skilled in the art. The profile of the tensioning mechanism may have forms including but not limited to elliptical, circular, hexagonal, octagonal or square. [0026] In certain embodiments, the external profile of the tensioning device has a form with parallel exterior surfaces, such as a square, hexagonal or octagonal form. The external profile may be used for the application of torque with a tool such as a wrench or other standard torque applying tool. [0027] In certain embodiments, the tensioning mechanism has at least one aperture. The aperture passes through the tensioning mechanism perpendicular to central axis of the mechanism typically intersecting the central axis. The aperture allows for torque application through the use of a rod or other shaft-like object inserted into the aperture. After torque application it may be desired to dispose a rod in the aperture to prevent counter-rotation by engaging the rod with the structure, such as concrete, to which an apparatus comprising a tensioning mechanism is applied. It will be appreciated by those skilled in the art that such apertures are typically in a medial section of the tensioning mechanism. Furthermore, it may be desired to have a plurality of apertures. The additional apertures can be angularly displaced from other apertures such as on 45-degree or 90-degree increments that allow for easier adjustment of the tensioning mechanism in tighter locations. The apertures may be coplanar to the axis of the central axis. In certain embodiments, the apertures may be located on offset yet parallel planes that are perpendicular to the central axis of the tensioning mechanism. [0028] Embodiments of the present disclosure may be used in a system comprising at least one tensioning mechanism and at least two tension application components. Furthermore, different tensioning components may be used interchangeably with a tensioning mechanism to allow system customization for each application. BRIEF DESCRIPTION OF FIGURES [0029] FIG. 1A —A top view of a post tensioning system [0030] FIG. 1B —A side view of a post tensioning system [0031] FIG. 2 —A side view of a turnbuckle embodiment of a tensioning mechanism [0032] FIG. 3 —A side view of a tension application component [0033] FIG. 4A —A side view of a tension application component [0034] FIG. 4B —A top view of a tension application component [0035] FIG. 5A —A top view of a post tensioning system [0036] FIG. 5B —A side view of a post tensioning system [0037] FIG. 6A —A perspective view of a tension application component [0038] FIG. 6B —A top view of a tension application component [0039] FIG. 6C —A side view of a tension application component [0040] FIG. 7A —A top view of a post tensioning system [0041] FIG. 7B —A side view of a post tensioning system [0042] FIG. 8A —A bottom view of a tension application component [0043] FIG. 8B —A side view of a tension application component [0044] FIG. 8C —A top view of a tension application component [0045] FIG. 9A —A perspective view of a post tensioning system [0046] FIG. 9B —A side view of a post tensioning system [0047] FIG. 9C —A front view of a post tensioning system [0048] FIG. 10A —A side view of a tension application component [0049] FIG. 10B —A top view of a tension application component [0050] FIG. 11 —A perspective view of a tension application component DETAILED DESCRIPTION [0051] In certain embodiments of the present invention, a modular apparatus and system provides tension to existing structures, such as an existing concrete installation, wherein it is desired to provide structural reinforcement. Tensioning may be desired in many scenarios such as the cross-linking of independently poured concrete installations or providing tension in “post-tensioning” to repair a concrete installation using tensile strengthening features. The application of metal structure for the tensile reinforcement is typically placed across a mechanical failure zone such as a fissure or crack where the concrete installation has mechanically failed. [0052] An apparatus 100 , as shown in FIGS. 1A and 1B , embodying the inventive principles of the invention comprises at least two tension application components 101 a and 101 b and one tensioning mechanism 102 disposed and attached therebetween. When the tension application components 101 are constrained, the actuation of the tensioning mechanism 102 applies tensile force to the tension application components 101 resulting in placing the apparatus in a tensile state. Certain embodiments of such an apparatus may comprise an overall length of 30.5 cm (12 in). [0053] The tension application component 101 translates forces from the tensioning mechanism 102 to the structure by attaching to a structure, such as a concrete installation. The tension application component 101 may also be attached to two or more independent elements or structures. It will be appreciated that the tension application components 101 may comprise a variety of forms including, but not limited to, a post-like device, hook, loop and/or plate with attachment features for attachment to a structure. In certain embodiments the apparatus 100 permits modular use of a variety of tension application components wherein the apparatus may be used with two tension application devices of similar or dissimilar size, shape or form. [0054] In certain embodiments of the apparatus, as shown in FIG. 2 , a tensioning mechanism 102 comprises two axially aligned threaded female features, 201 a and 201 b , having opposing threading at first and second distal ends of the tensioning mechanism 102 . For instance, an embodiment of a tensioning mechanism 102 may comprise 201 a having standard clockwise threading and the 201 b having counter-clockwise threading. This configuration of tensioning mechanism 102 is commonly referred to as a turnbuckle. In certain embodiments a tensioning mechanism 102 comprises a length of 10.2 cm (4.0 in) and diameter of 15.875 mm (0.625 in) In such an embodiment the tension application components 101 a and 101 b , as shown in FIG. 3 , have a cylindrical profile with a length of screw threading, 301 a and 301 b , at a proximal end 302 to engage with the threaded female features, 201 a and 201 b , of the tensioning mechanism 102 . Furthermore, the distal section 303 of the tension application component has a bend which provides a post-like form 304 to allow the application of force upon an existing structure or aperture prepared in a structure for the placement of the tension application components 101 a and/or 101 b . It will be appreciated that the bend in the tension application components 101 a and/or 101 b may comprise a plurality of angular bends typically totaling at least 90-degrees. In certain embodiments the female threaded features as illustrated by FIG. 2 , the threaded female features 201 a and 201 b have screw threading having a lead of 1.5875 mm (0.0625 in) and a diameter of 9.525 mm (0.375 in). It will be appreciated to those skilled in the art that lead, surrounding male threaded features, indicates the axial travel for a single revolution of the screw thread. In such an embodiment, the screw threading 301 a and 301 b , seen in FIG. 3 , also have screw threading having a lead of 1.5875 mm (0.0625 in). Such embodiments may be designated with ANSI thread designation as ⅜-16 per ANSI/ASME B1.1-1989 (R2001). Certain embodiments of a post-like form 303 as seen in FIG. 3 , comprises a length of 44.45 mm (1.75 in) and diameter of 9.525 mm (0.375 in). It will be appreciated that other embodiments may have post-like forms of different lengths. It will be appreciated that a tension application component 303 , shown to have a matching cross-section to the male threaded features 301 a and 301 b , are not limited to a round cross-section or dimensions matching that of the male threaded features 301 a and 301 b . It will be further appreciated that the threading associated with the male threaded features 301 a and 301 b , seen in FIG. 3 , and the female threaded features 201 a and 201 b may comprise threading larger or smaller than embodiments described herein. Certain embodiments of a tension application feature 101 a and 101 b may comprise a length of 12.7 cm (5.0 in). [0055] It will be appreciated by those skilled in the art that a post-tensioning device may be made of a steel alloy designated as a hot rolled and proof stressed alloy steel conforming to ASTM A722 CAN/CSA (G279-M1982). It will be further appreciated that certain embodiments may be made of a steel allow such as AISI 1144, sometimes referred to by an associated trade name of Stressproof®. AISI 1144 steel is appreciated to those skilled in the art as a is a carbon-manganese grade steel which is severely cold worked to produce high tensile properties. [0056] Certain embodiments such as those shown in FIGS. 1A-3 are directed to the repair of a concrete structure where a fissure or crack has occurred due to mechanical failure. The surface is prepared by placing apertures in the concrete on either side of the fissure or crack. The apertures are positioned at a distance that generally corresponds to the the length of the apparatus 100 with attached tension application components 101 a and 101 b prior to actuation of the tensioning mechanism 102 which shortens the mechanism. The distal end 303 of tension application components 101 a and 101 b , such as the those shown in FIG. 3 , into the corresponding apertures of the prepared surface. Tension can then be applied by actuating the tensioning mechanism 102 to creating post-tensioning in the area surrounding the crack or fissure. [0057] In certain embodiments of the apparatus as shown in FIGS. 4A-5C , a tension application component 401 applies tensile load across a desired structure. The tension application component 401 comprises an attachment feature 402 at a proximal end 403 for engaging with a tensioning mechanism and an aperture 404 . The distal end 405 has a tension application feature 404 , such as an aperture or hook-form, configured to engage with features installed in the structure. Such features include, but are not limited to, a post or rebar, affixed to the structure. [0058] Certain embodiments of the invention, as shown in FIGS. 6A, 6B, 7A, 7B and 7C , comprise a tension application component 601 that engages with a tensioning mechanism 102 . A proximal end 603 of the tension application component 601 has an attachment feature 602 configured to engage with the tensioning mechanism 102 . The distal end 605 of the tension application component 601 is configured to engage the apertures of a prepared surface or the edges of an existing structure by having a plurality of post-like features 604 . Having a plurality of post-like features 604 distributes the load of the tensioning mechanism 102 across a larger area. The distribution of forces allows the installation of a post-tensioning apparatus 601 in conjunction with structures that cannot offer structural stability for an apparatus with a more concentrated loading. Certain embodiments of a tension application component 601 as seen in FIG. 6A-C has a two parallel post-like features 604 interconnected such that the post like features are separated by a distance of 8.89 cm (3.5 in). In the scenario which a user may want to use more than one post-tensioning apparatus 601 , the plurality of post-like features 604 allows the use of fewer post-tensioning apparatuses 601 over a given length of a fissure or crack to achieve stronger structural ability. Certain embodiments of an aperture 404 as seen in FIG. 4 , comprise a length of 19.05 mm (0.75 in) and width of 12.7 mm (0.5 in). Certain embodiments of a tension application feature 405 as seen in FIGS. 4A and 4B has a length of 59.18 mm (2.33 in), width of 31.75 mm (1.25 in) and thickness of 9.525 mm (0.375 in). [0059] Certain embodiments have a tension application component. Such as those shown in FIGS. 8A, 8B, 8C, 9A, 9B and 9C , a tension application component 801 comprises a plate-form 802 , the plate-form 802 having at least one aperture 803 . The plate-form 802 affixes to a structure, typically using at least one aperture 803 in the plate-form 802 . The plate-form 802 may be affixed to the structure through an aperture 803 . Fixation strategies include the use of threaded features, masonry anchors and other methods known to those skilled in the art. This allows the application of tensile load to the structure at the desired location. The plate-form 802 further comprises and engagement features, such as a threaded male component 804 extending outward from the surface of the plate-form, typically axially parallel to the bore of an aperture in the plate-form. This engagement feature is configured to engage with a tensioning mechanism 102 . In such an embodiment, a tension application component 801 can be attached to a first surface at an angle to, typically orthogonal, and attached to a second surface. This allows post tensioning across a crack or fissure that has occurred proximal to a corner where two surfaces of the structure or adjacent structures meet at an angle. It will be appreciated to those skilled in the art that a plurality of apertures 803 may be used to affix the plate-form 802 to the structure. The use of a plurality of apertures 803 in conjunction distributes the load born by the fixation features. Certain embodiments of a plate-form 802 has a length of 12.7 cm (5.0 in), width of 31.75 mm (1.25 in) and thickness of 6.35 mm (0.25 in). In such embodiments, a plate-form 802 further comprises a male threaded component 804 disposed centrally to the width of the plate-form and 8.255 mm (0.325 in) from a longitudinal end of the plate-form, extending orthogonally from the plate-form. [0060] Certain embodiments of the invention, as shown in FIGS. 10A and 10B , comprise a tension application component 1001 having at least two parallel post structures 1002 . The two parallel post structures 1002 are disposed at an angle from a connecting body 1003 . The tension application component 1001 has an aperture 1004 located medial to the post structures 1002 . The aperture 1004 is also typically axially parallel to the post structures. The tension application component 1001 distributes the load applied to the structure and provides a post-tensioning effect to a larger area. In certain embodiments, a second tension application component, such as 101 a in FIG. 3 , has a post feature attached to a tensioning mechanism, where the post-feature 304 is disposed through the medially located aperture 1004 . Certain embodiments of a tension application component as seen in FIG. 10B comprises a medially located aperture 1004 in a medially mounted tab 1005 affixed to the tension application component. In such embodiments, a medially located aperture 1004 comprises a width of 12 mm (0.473 in) and length of 12.7 mm (0.5 in), the medially mounted tab 1005 having a length and width of 25.4 mm (1.00 in), and the tension application component having an overall length of 30.5 cm (12.0 in). [0061] Certain embodiments have a tension application component. In certain embodiments of, as shown in FIG. 11 , the tension application component comprises a plate-form 1102 . The plate-form 1102 affixes to a structure to apply tensile load to the structure at the desired location. The plate-form 1102 can be affixed by masonry anchors or threaded features through apertures 1103 in the plate-form 1102 , welding or other methods known to those skilled in the art. The plate-form 1102 further comprises a fixation point 1104 configured to engage through a secondary tension application component, such as having a loop, hook, post-like feature or aperture. In the case of the plate-form 1102 being fixated through the use of a plurality of fasteners or anchors, this distributes any tensile loading applied to the fixation point such as when applying post-tensioning across a fissure or crack. The distributed load can also provide tension between independent structures where other types of tension application components cannot. For example, post-like forms create a higher localized concentration of stress and do not offer the necessary structural stability to provide tension between independent structures. [0062] In certain embodiments of the invention such as that shown in FIG. 2 , the apparatus comprises a tensioning mechanism, the tensioning mechanism 102 having consistent cross-section. The tensioning mechanism 102 can have female threaded features, 201 a and 201 b , at its distal ends. The threaded receptacles, 201 a and 201 b , having opposing threading direction. Thus, when engaged with rotationally constrained male threaded features, the opposite threading direction allows both male threaded features to be drawn toward the center of the tensioning mechanism 102 when rotated in a first direction and forces the male threaded features away from center when rotated a second direction, opposite the first direction. Alternatively, it will be appreciated that the tensioning mechanism may have male threaded features and the tension application components have female threaded features. [0063] In certain embodiments, the tensioning mechanism has a torque application feature. The torque application feature actuates the tensioning mechanism by to applying rotational forces to tension application components. The torque application feature may have different individual forms or a combination of forms as known to those skilled in the art. The profile of the tensioning mechanism may have forms including but not limited to elliptical, circular, hexagonal, octagonal or square. [0064] In certain embodiments the tensioning mechanism 102 , such as that shown in FIG. 2 , has at least one at least one torque application aperture 202 . The torque application aperture 202 , passes through the tensioning mechanism perpendicular to the central axis of the mechanism typically intersecting the central axis of the tensioning mechanism 102 . The torque application aperture 202 allows for torque application through the use of a rod or other shaft-like object. After torque application, it may be desired to dispose a rod in the torque application aperture 202 to prevent counter-rotation by engaging the rod with the structure, such as concrete, to which an apparatus comprising a tensioning mechanism 102 is applied. It will be appreciated to those skilled in the art, that apertures 202 are typically be in a medial section of the tensioning mechanism 102 . Furthermore, it may be desired to have a plurality of apertures. The additional apertures 202 can be radially displaced from other apertures such as on 45-degree or 90-degree increments that allow for easier adjustment of the tensioning mechanism 102 in tighter locations. The apertures 202 may be coplanar to the axis of the central axis. In certain embodiments, the apertures 202 may be located on offset yet parallel planes perpendicular to the axis of the central axis of the tensioning mechanism 102 . [0065] In certain embodiments, the external profile of a tensioning device comprises a form with parallel exterior surfaces, such as a square, hexagonal or octagonal form, wherein the external profile may be used for the application of torque with a tool such as a wrench or other standard torque tool. [0066] Embodiments of the invention disclosed herein may be used in a system comprising at least one tensioning mechanism and at least two tension application components wherein the tensioning components are interchangeably with a tensioning mechanism to allow system customization for each application. In such an embodiment of a system the tension application components may have a threading to match the tensioning mechanism with right-hand or left-hand threads alternatively. It will be appreciated that a system comprising at least one tensioning mechanism and at least two tension application components may comprise a first tension application component of a first type and a second tension application component of a second type. [0067] In the foregoing specification, specific embodiments have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present teachings. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.

The present invention pertains in general to post-tensioning apparatus and systems surrounding the fabrication and repair of concrete and other construction materials. The present invention surrounds apparatus and system directed to the post-tensioning for reinforcement of existing and new concrete structures through the application of tensile forces between two attachment points anchored to the structure to be mended.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of and claims priority to Patent Cooperation Treaty Application No. PCT/EP2015/060034, filed on May 7, 2015, which claims priority to German Application No. DE 10 2014 106 596.4 filed on May 9, 2014, each of which applications are hereby incorporated herein by reference in their entireties. BACKGROUND [0002] Means for fastening bellows produced from elastomer materials, in particular pleated bellows and roller bellows, are well known. Thus, for some time so-called mutually overlapping retaining straps have been available that attain a clamping effect by tautening the two free strap ends with suitable means. However, the pleated bellows can be damaged in the region of the free strap ends, and the latter also require considerable space for installation. A number of so-called endless annularly closed clamping rings have therefore been suggested in the past. Their diameter is reduced by crimping, i.e., by radial compression by means of suitable tools, so that during the crimping process a bellows is ultimately securely held on a fastening body, for instance, a joint housing or a shaft. [0003] To produce such endless annularly closed clamping rings, it is known to roll tape pieces trimmed from an endless tape material and butt-weld them to one another perpendicular to the center line of the ring, but this technique is very time-consuming. In contrast, instead of such welding, known from DE 40 21 746 A1 is providing on the first and second free ends of a tape segment outside and inside closure strips that are embodied complementary to one another and have undercut regions so that, when the closed connection is under tensile load, inwardly directed forces that permit a point connection of the two complementary closure strips act on the outer closure straps. An end region may be embodied, for instance, such that an essentially T-shaped head piece is embodied thereon, while the second end region complementary hereto provides a jaw-shaped fork adapted to the first end region, the two end regions linearly butting and engaging one another. A plurality of dovetail or T-shaped strips may also be provided on the ring width. Such endless annularly closed tensioning rings described in DE 40 21 746 A1 have become known as such with a so-called puzzle lock. However, it is a disadvantage of the endless tensioning ring known from DE 40 21 746 A1 that these can open occasionally, whether during transport to the consumer or user of the closed endless tensioning rings, or whether during use of the latter, for instance for retaining pleated bellows or roller bellows on outer joint housing parts or shafts. There is therefore a need for fasteners that have improved closure of the two free ends of a strip-like segment for forming an endless tensioning ring. SUMMARY [0004] Disclosed herein is a fastener, in particular for bellows, comprising a male end segment and a female end segment complementary to the male end segment, as well as the use thereof for fastening bellows on joint housings and/or shafts, which fastener has an improved closing behavior. The fastener has at least one undercut region being embodied in the male end segment. [0005] The fastener, in particular for bellows, comprises a male end segment and a female end segment complementary to the male end segment, each having at least a first transversal undercut region, and wherein a first width b 1 of the male end segment is determined either by the minimum width b 1 of a first foot segment extending away from a first base in the first male transversal undercut region, or, if there is a recess that is arranged displaced beyond the base in a length direction of the fastener, by minimum widths b 11 and b 12 of longitudinal segments in the region of the recess, and wherein the female end segment has a first and a second outer longitudinal segment, each having a second minimum width b 21 and b 22 in the region of the first female transversal undercut and, possibly, having an innerly disposed transversal undercut region with a second foot segment, wherein the latter extends away from a second base and has a third minimum width b 3 in the innerly disposed transversal undercut region, wherein b 1 :(b 21 +b 22 +b 3 ) or (b 11 +b 12 ):(b 21 +b 22 +b 3 ) is in a range from approximately 0.79 to approximately 1.27. [0006] The specific cross-sectional width ratios help to ensure that, given the many stresses to which the fastener is exposed during use, it experiences only slight crack formation between the contact surfaces of the male and female end segments so that the service life in use is extended. Apart from the claimed ranges for the cross-sectional width ratio b 1 :(b 21 +b 22 +b 3 ) or (b 11 +b 12 ):(b 21 +b 22 +b 3 ), wherein b 3 is only to be taken into consideration if there is an innerly disposed transversal undercut region, analyses of a number of generic fasteners using finite element methods have found the occurrence of transversal crack formations, that is, those transverse to a longitudinal extension of the fastener, especially immediately adjacent to an outer wall of the fastener. These occur in particular when there is tensile-bending strain. With the present fastener, these crack formations are significantly reduced or do not occur. [0007] Both the male and the female end segments may have a first transversal undercut region, but they may also each additionally have a second or third or fourth transversal undercut region. The number of transversal undercut regions in the male end segment and in the female end segment is always equal. The possibly present at least one innerly disposed transversal undercut region of the male end segment likewise has a counterpart in an innerly disposed transversal undercut region of the female end segment. It is possible that exactly one innerly disposed transversal undercut region is present in the female end segment and in the male end segment. In the context of the present application, a first transversal undercut region relative to the male and female segments shall be construed to mean the transversal undercut region next to the base of the male segment, wherein in the case of the female end segment this refers to the fastener being in the closed condition. Alternatively, with respect to the female segment when the fastener is in the open condition, the first transversal undercut region may be defined as the undercut region next to an end of the female end segment. The end of the female end segment is associated with the base of the male end segment in the closed condition or is immediately adjacent thereto. If only one transversal (outer) undercut region is provided in the male and female end segments, therefore just a first undercut region for each, these are associated with one another when the fastener is in the closed condition. In contrast, if more than one transversal male and female undercut regions are provided, they are not associated with one another. For instance, in this case the first male transversal (outer) undercut region is associated with the second female transversal (outer) undercut region. There are the same number of male and female transversal (outer) undercut regions. [0008] With respect to determining the cross-sectional width ratios as disclosed and/or claimed herein, there is a first, second, third, and fourth stage depending on the first, second, third, fourth, etc. transversal undercut regions. The first stage relates to the first transversal undercut regions of the male and female end segments, the second stage relates to the second transversal undercut regions of the male and female end segments, the third stage relates to the third transversal undercut regions of the male and female segments, the fourth stage relates to the fourth transversal undercut regions of the male and female segments, etc. [0009] When the present disclosure addresses an inner or interiorly disposed (transversal) undercut region, this means an undercut region that is formed exclusively using the embodiments of the male and female end segments, and has neither a direct transversal nor a direct longitudinal undercut with respect to an outer wall of the fastener. In this context, transversal means that undercuts are embodied transverse to a length direction of the fastener, the term “transverse” here encompassing not only transversal undercuts that run at a right angle to the outer wall of the fastener, but also those that run at an angle with respect to the outer wall of the fastener. In this context, longitudinal means that undercuts run in the length direction of the fastener, “length direction” meaning that they may run both approximately parallel to the outer wall of the fastener and at an angle thereto. The inner undercut region also has transversal undercuts, but these are formed in recesses of the female and/or male end segment and therefore do not relate to the outer wall of the fastener. [0010] For an interiorly disposed undercut region, it is always necessary for at least one recess to be provided in a center element, arranged in the male or female end segment, in which a complementary center element of the female or male end segment may engage. In the context of the present disclosure, more than one inner undercut region, for instance two or three undercut regions, may also be provided. [0011] The male segment may be considered as provided with a tongue-like projection. The latter has at least one foot part and at least one head part arranged thereon, wherein the head part, in the case of the male end segment, has first and second extensions that project beyond an outer contour of the foot part. The example of the female end segment with an interiorly disposed undercut region may also be considered mushroom-shaped or the like with respect to the foot segment with a head part, or may also be considered tongue-like. However, the extension of this tongue or this mushroom head in the length direction of the fastener is at most approximately 50% of that of the tongue-like projection of the male end segment, possibly between approximately 15% and approximately 42%. The foot segment with head part, arranged approximately centrally in the female end segment, may be considered to be a projection, especially a mushroom head-shaped projection, arranged on the base of the female end segment. This projection is possibly arranged on the base with longitudinal segments of the female end segment adjacent on both sides. The projection may project over the longitudinal segments in the length direction of the fastener or may be arranged within one of these defined spaces. The mushroom head-shaped projection of the female end segment is possibly arranged or arrangable inside the male end segment in a recess of the latter when the fastener is in the closed condition. Apart from any overcuts provided in edge areas for better connection when closed, an outer contour of the mushroom head-shaped projection of the female end segment essentially corresponds to an inner contour of the male end segment. A recess in the male end segment is arranged in a center element for forming an inner undercut region, possibly in a head part arranged there. The means for forming an inner undercut region on the male end segment possibly has a foot part that carries the head part with the recess. The head part possibly projects beyond the foot part, forming two extension parts. The recess is possibly provided between them. Outer or first, second, third, fourth, etc. transversal (outer) undercut regions shall be understood in the context of the present invention to be those regions that, with respect to the male end segment, are those undercuts that are transversal or longitudinally directly relative to the outer wall of the fastener. [0012] In the present disclosure, when an inner undercut region and at least one first outer or transversal undercut region are mentioned, undercut regions that have transversal undercuts are meant. Transversal undercuts in the context of the present disclosure are oriented transverse in any direction of the fastener apart from a length direction. They are possibly formed from linear and/or curved segments, frequently having different radii. [0013] The inner undercut region and the at least one outer or transversal undercut region extend in the length direction of the fastener, possibly between minimum widths, relative to the specific undercut regions, of the center elements arranged in the male and female end segments. For instance, an inner undercut region of the female end segment extends proceeding from the minimum width b 3 of the foot segment of the female end segment to the minimum widths b 61 and b 62 of the two extension parts of the head part of the male end segment. For instance, a first outer or transversal undercut region extends approximately between a region of minimum width b 1 of the first foot segment that is arranged on the first base of the male end segment to approximately a minimum width b 21 and b 22 of two longitudinal segments of the complementary female end segment, arranged on both sides of a second foot segment of the female end segment that is arranged centrally on the second base. [0014] Alternatively or additionally, the reason for the improved statically dynamic behavior is also the provision of the foot segment with the head part, which is arranged approximately in the center in the female end segment and which can be engaged in the male end segment embodied complementary thereto. A corresponding recess is provided there through which an inner undercut region is embodied in the male end segment. In addition to the inner undercut region, the male end segment has at least one outer or transversal undercut region. A female end segment in the context of the present disclosure describes such an undercut region, which receives a male end segment and is primarily lateral. [0015] The subject matter of the present disclosure is alternatively or additionally a fastener of the type cited above, a female end segment comprising a base on which is arranged a foot segment arranged approximately centrally there, on which is arranged a head part that projects laterally over an outer contour of the foot segment transverse and, seen in a transverse direction of the fastener, comprising lower lateral surfaces for embodying at least one inner undercut region in a recess of the male end segment. Both examples of the fastener, which may also be cumulative, are improvements with regard to both static and dynamic loads compared to those from the prior art. [0016] The disclosed fastener is possibly embodied in a ribbon-like form. It is produced in this shape and then bent to create a closed ring. In one example, therefore, the claimed fastener may be closed to create a closed ring, and especially may be embodied as a closed ring, the complementary male and female end segments being connected to one another. It may be advantageously provided that the male or female end segment may have material overcuts, especially in their respective head parts, but also in the foot part, wherein overcuts means material overcuts, so that when the ribbon-like fastener is closed to create a closed ring, deformations due to material overlays occur in these regions. Due to this, in regions in which cracks may be formed when the fastener is in use and are very highly stressed, this crack formation may be prevented so that the service life of the fastener embodied as a closed ring is extended in the fastening condition. [0017] By bending the strip-like fastener to create a closed ring and also by crimping for fastening, for instance, a bellows with the fastener on a shaft, for instance, forge deformations and/or other deformations of the male and female end segments occur. Therefore, in the present disclosure, when reference is made to geometric values, value-related terms such as parallel, etc., or value ranges such as for instance angles or radii, these references relate to the ribbon-like fastener, that is, not to the closed fastener. The minimum widths are generally approximately retained in a closed and crimped fastener. [0018] In the present disclosure, when the term “approximately” is used in reference to concrete values, value-related terms like parallel, etc. or ranges of values, these shall be construed to include such deviations as the person skilled in the art considers to be normal in the field of the technical expert, especially deviations of +/−10% of the specific value or term, possibly +/−5% of the specific value or value-related term. [0019] In one example of the fastener, the widths b 1 or (b 11 +b 12 ) and (b 21 +b 22 ) together are at least 38%, possibly at least 40%, of a total width b of the fastener. The aforesaid widths are possibly approximately 38% to approximately 80%, possibly approximately 40% to approximately 75%, of the total width b of the fastener. A longitudinal force acting on the fastener can be transferred best to the center element of the male and female end segment, especially to the male foot segment, with the ratios or ranges provided above. [0020] In another example, arranged in at least one transversal undercut region are notch radii of at least approximately 0.3 mm, possibly of at least approximately 0.5 mm, and possibly particularly in a range from approximately 0.3 mm to approximately 0.9 mm. In a further example, another notch radius of a maximum of approximately 0.3 mm is associated with a notch radius of at least approximately 0.3 mm. Particularly possible in the context of the present invention, provided in the at least one transversal undercut region are notch radii of approximately 0.4 mm to approximately 0.9 mm, and associated with these are a further notch radius of approximately 0.2 mm to approximately 0.35, possibly of approximately 0.2 mm to approximately 0.3 mm. In another example of the present invention, a notch radius is at least approximately 0.3 mm, possibly at least 0.5 mm, and possibly in a range from approximately 0.4 mm to approximately 0.85 mm in the transition from the first base of the male end segment to the foot segment. Here, as well, different radii may possibly be used, as described in the foregoing. [0021] Notch radii of at least approximately 0.3 mm, possibly at least approximately 0.5 mm, and more possibly particularly in a range from approximately 0.3 mm to approximately 0.9 mm are arranged in the region between lateral longitudinal surfaces of the foot segment and lateral transverse surfaces of the extension parts of the male end segment. It may advantageously be provided that different radii are used, wherein in the region of the minimum width b 1 of the foot segment of the male end segment greater notch radii in a range from approximately 0.7 mm to approximately 0.9 mm are advantageously provided, to which are connected minimum radii in a range of approximately 0.25 mm to approximately 0.5 mm, possibly in a range from approximately 0.3 mm to approximately 0.4 mm. [0022] In one particularly example of the present invention, provided in the region of minimum widths of the first, second, third, fourth, etc. transversal undercut regions or innerly disposed transversal undercut regions are the greatest possible notch radii, in particular those in a range from approximately 0.5 mm to approximately 0.9 mm, particularly possibly those in a range from approximately 0.6 mm to approximately 0.9 mm, to which are connected minimum notch radii in a range of approximately 0.2 mm to approximately 0.35 mm. This advantageously suppresses the static or dynamic load-related widening of cracks and the like in the undercut regions of the inventive fastener that are critical for load transfer. [0023] The first foot segment on the first base of the male end segment possibly has a greater width b 4 than the first minimum width b 1 . It is furthermore possible that a transition angle γ (gamma) is between the first base and the first foot segment of the male end segment in a range from approximately 90.5° to approximately 110°, possibly in a range from approximately 91° to approximately 102°. Using this specific example of the first foot segment of the male end segment it is advantageously possible to realize the greatest possible notch radii in critical regions, especially in regions of minimum widths b 1 . [0024] Possibly provided at the first base of the male end segment are at least two lengthening segments that may be arranged in complementary recesses of the female end segment. These lengthening segments thus provide additional transversal undercut regions, which permits improved meshing of the female end segment with the male end segment. [0025] Lateral surfaces formed by the first foot segment of the male end segment are advantageously embodied at an acute angle to lateral transverse surfaces embodied in the first male transversal undercut region by first and second extension parts. [0026] The extension parts comprise lateral transverse surfaces for embodying the at least one outer transversal undercut region. The lateral transverse surfaces, with lateral longitudinal surfaces of the foot segment of the male end segment, form an acute angle W in a range from approximately 45° to approximately 88°, possibly in a range from approximately 68° to approximately 88°, possibly in a range from approximately 75° to approximately 86°. Possibly, the acute angle W is 80°+5°, which means that an acute angle W of 80° is possible, but it may have a production tolerance of +5°. [0027] The minimum widths b 21 and b 22 of both outer longitudinal segments and the minimum width b 3 of the second foot segment of the female end segment, when present, are selected such that they have a ratio b 1 :(b 21 +b 22 +b 3 ) or (b 11 +b 12 ):(b 21 +b 22 +b 3 ) of approximately 0.79 to approximately 1.27, possibly approximately 0.85 to approximately 1.18, more possibly approximately 0.95 to approximately 1.05 to the minimum width b 1 of the foot segment of the male end segment or to the minimum widths b 11 and b 12 of the longitudinal segments in the region of the recess. This ratio has proved to be essential during the calculation by means of finite element analysis for supplying the best figures for tensile stresses that occur. In principle the ratios of the minimum widths (cross-section width ratios) of the male and female end segments are formed systematically at a first male and a first female stage, or at a second male and second female stage, or at a third male and third female stage, etc., relative to such outer transversal undercut regions, and are possibly in the aforesaid regions in the context of the present disclosure. [0028] It is particularly possible that a width b 5 of the first base or of the lengthening segments that are provided on the first base of the male end segment is at least 1.0 mm, the width b 5 is possibly in a range from approximately 1.2 mm to approximately 2.0 mm, if lengthening segments are provided, wherein the width b 5 of the first base then possibly essentially equals the width of the lengthening segments. If no lengthening segments are provided, the width b 5 of the first base is possibly between approximately 1.5 mm and approximately 3.2 mm. [0029] In a finite element analysis, it was shown that the fastener has excellent values not only for static tensile elongation, but also for dynamic tensile-bending strain. In addition, finite element methods demonstrated that the inventive fastener yield very good values for a static crack opening, determined in an intermediate stress step during the assembly of the binder. For all of the aforesaid variables that are determined normalized using finite element methods, values less than 100%, and possibly less than 80%, could be determined. This means that only extremely small crack openings will occur in use or during post-production delivery of the closed, ring-shaped fastener. The values for dynamic tensile-bending strain are in particular <=100 possibly at a maximum of approximately 80%, possibly a maximum of approximately 75%, possibly in a range from approximately 20% to approximately 80%, and thus are values that are clearly below those values for puzzle connections according to the prior art, likewise determined by finite element methods and normalized, the values of which are often significantly greater than 100%. [0030] In one example, the second foot segment of the female end segment, when present, is embodied proceeding from the base thereof tapering to a minimum width b 3 . Furthermore, in this example a transition angle β between base and second foot segment is in a range from approximately 91° to approximately 110°, possibly in a range from approximately 93° to approximately 108°. Furthermore, arranged between lateral surfaces of the second foot segment and the lower lateral surfaces of the head part of the female end segment there can be radial regions having notch radii of at least approximately 0.3 mm, further possible are notch radii of at least approximately 0.5 mm, and yet further possible are notch radii in a range from approximately 0.3 mm to approximately 0.9 mm. It is possible that different notch radii are provided in the aforesaid radial ranges. Particularly possible in the range of minimum widths, such as for instance the minimum width of the second foot segment of the female end segment, are radii of approximately 0.7 mm to approximately 0.9 mm, possibly approximately 0.8 mm to approximately 0.9 mm, to which then a minimum radius in a range from approximately 0.3 mm to approximately 0.4 mm can connect. The aforesaid minimum radii, which are possibly in a range from approximately 0.25 mm to approximately 0.5 mm, possibly in a range from approximately 0.3 mm to approximately 0.4 mm, serve to make available the most possible functions such as undercuts or load-bearing cross-sectional surfaces of the inventive fastener on the available narrow space. A normal width b of a fastener is in a range from approximately 8 mm to approximately 20 mm, possibly approximately 9 mm to approximately 13 mm. However, these minimum radii are not used in the region of the minimum widths, because otherwise strong notch effects would occur there. Only when there is at least a 0.1 mm enlargement of the cross-section due to a larger radius, in particular a radius in a range from approximately 0.7 mm to approximately 0.9 mm, should a minimum radius be provided connecting thereto. In the region of a critical cross-section, that is, a minimum cut or width of the male or female end segment, for instance a minimum width of the foot segments, possibly the largest possible notch radii are used in a range from approximately 0.4 mm to approximately 1 mm, possibly to approximately 0.9 mm. The transition from a minimum radius to a larger radius or vice versa is always tangentially continuous. The aforesaid local radii of curvature are advantageously determined by comparing different known conforming radii. [0031] At least parts of, possibly all, the lateral surfaces of the head part of the female end segment, when present, are advantageously embodied curved with notch radii of at least approximately 0.3 mm, possibly of at least approximately 0.5 mm, more possibly with notch radii in a range from approximately 0.3 mm to approximately 0.9 mm. In this case, as well, different radii may connect to one another, as described in the foregoing. One lateral head surface of the head part is embodied in at least one sub-region approximately parallel to the base of the female end segment. It is particularly possible that the radial regions of the lateral surfaces of the head part transition, with notch radii of at least approximately 0.5 mm, possibly at least approximately 0.7 mm, particularly possibly in a range of approximately 0.7 mm to approximately 0.9 mm, into the lateral head surface of the head part. A linear region without any curvature may be provided following the radial region. [0032] In one example, an outer longitudinal segment whose outer wall transitions flush into the outer wall of the fastener is arranged on both sides of the foot segment of the female end segment. In their ends that are associated with the male end segment, the longitudinal segments may have recesses in which lengthening segments of the male end segment may be arranged. This provides additional longitudinal undercuts that further prevent the risk of a connection between male and female end segments in a closed inventive fastener from being opened if there is a bending stress. [0033] In a first embodiment, the two outer longitudinal segments project beyond the head part of the female end segment in a length direction of the fastener. In a second embodiment, as seen in a length direction of the fastener, the head part of the female end segment projects beyond the outer longitudinal segments, or projects out beyond the ends of the outer longitudinal segments. In the second embodiment, therefore, the male end segment has a recess embodied beyond the base thereof as seen in the length direction of the strip, in which recess the foot part engages with the head part of the complementary female end segment. [0034] In one example of the inventive fastener, in addition to the at least one outer transversal undercut region, the male end segment includes at least one inner undercut region. It may also be provided that at least two or three or even more transversal undercut regions are provided, but possibly one or two or three transversal undercut regions are provided. [0035] In another example, arranged on the end of the foot segment of the male end segment facing away from the base is a head part with extension parts that embody the inner undercut region, in particular in that they form a recess for foot part with head part of a female end segment. [0036] Lateral surfaces of the extension parts are advantageously approximately parallel to the outer wall of the fastener. However, it may also be provided that the lateral surfaces are slightly angled to the outer wall of the fastener, i.e., especially advantageously the head part of the male end segment as seen in the long direction of the fastener tapers somewhat. The deviations from a parallel orientation are possibly in a range from approximately +/−10°, more possibly in a range from approximately +/−5°. The lateral surfaces of the extension parts may be not only linear, which is preferred, but also in another manner, in particular they may have bent regions that form bulges or indentations in the extension parts of the head part of the male end segment. The transition between the lateral surfaces of the extension parts of the head part of the male end segment and the particular lateral head surfaces thereof, which may be associated with the base of the female end segment, is possibly at a right angle. For technical production reasons, however, minimum notch radii may be up to 0.3 mm. This cannot be avoided for technical production reasons. [0037] Furthermore, between the extension parts is a recess that is complementary to the foot segment with head part, when present, arranged on the base of the female end segment. The recess may be described as approximately mushroom head-shaped. Because of this, the center elements that are arranged in the male end segment and that comprise foot part and head part with the two extension parts and the recess, are shaped something like a stag beetle. When more than one inner undercut region is provided, tree-like contours may then be added, for instance. [0038] In another example, a length l of the foot segment and of the head part with the extension parts of the male end segment is shorter than a width b of the fastener. The length l is possibly approximately 70% to approximately 98%, more possibly approximately 78% to approximately 95%, of the width b of the fastener. [0039] The present disclosure further relates to the use of the fastener for fastening bellows on joint housings, in particular on outer joint housing parts and/or shafts, especially of automobiles, especially of constant velocity joints. From bellows and a fastener a system is formed that makes it possible to fasten bellows. In particular, this system has a pleated bellows and/or a roller bellows. SUMMARY OF THE DRAWINGS [0040] The foregoing and other advantages of the present fastener are explained in greater detail using the following figures. [0041] FIG. 1 is a top view onto a ribbon-like inventive fastener in a first example; [0042] FIG. 2A is a male end segment of the fastener according to FIG. 1 ; [0043] FIG. 2B is a female end segment of the fastener according to FIG. 1 ; [0044] FIG. 3 is a perspective elevation of the fastener according to FIGS. 1 through 3 in the closed ring condition. [0045] FIG. 4 is a top view onto a second example of a closed ring-shaped fastener; [0046] FIG. 5 is a third example of a closed fastener; [0047] FIG. 6 is a fourth example of a closed fastener; [0048] FIG. 7 is a fifth example of a closed fastener. [0049] FIG. 8 is a sixth example of a closed fastener; [0050] FIG. 9 is a seventh example of a closed fastener; [0051] FIG. 10 is an eighth example of a closed fastener; [0052] FIG. 11 is a ninth example of a closed fastener; and, [0053] FIG. 12 is a detail Y from FIG. 4 . DETAILED DESCRIPTION [0054] It should first be noted that the examples of the fastener depicted in the figures should not be interpreted as limiting; for instance, two or more foot segments with head part and extension parts may also be arranged at the base of the female and male end segments in the case of the male end segment. The features described in the figures may be combined to create another embodiment with the features provided in the description above. Moreover, it should be noted that the reference numbers indicated in the description of the figures do not limit the scope of protection for the present invention, but instead merely refer to the exemplary embodiments illustrated in the figures. Provided no information to the contrary is explicitly provided, identical parts or part with the same function have the same reference numbers in the following. [0055] FIG. 1 is a top view onto a first example of a fastener 10 , which is shown in a ribbon-like shape, i.e., in the non-closed condition. The fastener 10 has a male end segment 14 and a female end segment 12 between which a strip segment 12 is arranged. The fastener 10 has an outer wall 11 on both sides. [0056] FIG. 2A depicts a first embodiment of the male end segment 14 of the fastener 10 according to FIG. 1 . A width b, determined between the outer walls 11 , of the fastener 10 or strip segment 12 , is greater than a length l of the male end segment, measured between a base 22 and lateral head surfaces 33 . 1 and 33 . 2 . The length l is approximately 80% of the width b. [0057] The male end segment 14 has a foot segment 20 and a head part 21 . The head part 21 has two extension parts 32 . 1 and 32 . 2 that project laterally beyond an outer contour of the foot part 20 . The foot part 20 has lateral longitudinal surfaces 30 . 1 , 30 . 2 , an obtuse angle γ (gamma), approximately 93°, being formed between the base 22 and the lateral longitudinal surfaces 30 . 1 and 30 . 2 . A notch radius r 5 of approximately 0.3 mm is provided in the region of the transition from the base 22 to the lateral longitudinal surfaces 30 . 1 and 30 . 2 . The foot part 20 is embodied tapering to a minimum width b 1 . Provided following this minimum width b 1 is a first notch radius r 1 , having a value of 0.8 mm, which transitions continuously tangentially into a notch radius r 2 of 0.3 mm. These notch radii r 1 and r 2 represent the transition from the lateral longitudinal surfaces 30 . 1 and 30 . 2 of the foot segment 20 to lateral transverse surfaces 34 . 1 and 34 . 2 of the extension parts 32 . 1 and 32 . 2 , which lateral transverse surfaces 34 . 1 and 34 . 2 are arranged in a first and only outer undercut region 26 . These then transition into lateral surfaces 35 . 1 and 35 . 2 of the extension parts 32 . 1 and 32 . 2 with a minimum notch radius r 3 of 0.3 mm and connecting thereto continuously tangentially with a notch radius r 4 of 0.8 mm. The lateral surfaces 35 . 1 and 35 . 2 are not embodied running parallel to the outer wall 11 of the fastener 10 , but instead at an angle of approximately 3° thereto, so that the extension parts 32 . 1 and 32 . 2 are embodied somewhat tapering toward the lateral head surfaces 33 . 1 and 33 . 2 thereof that can be associated with the female end segment 16 . This provides a region, following the notch radius r 4 , having a minimum width b 2 in the complementary female segment 16 , as may be seen below in FIG. 2 b . In the male end segment 14 , the foot segment 20 has a greater width b 4 on the base 22 than in the region of the minimum width b 1 . [0058] The transition between the lateral longitudinal surfaces 35 . 1 and 35 . 2 of the extension parts 32 . 1 and 32 . 2 into the lateral head surfaces 33 . 1 and 33 . 2 runs essentially at a right angle. [0059] Due to production tolerances, however, notch radii may be up to 0.3 mm. [0060] The lateral transverse surfaces 34 . 1 and 34 . 2 of the extension parts 32 . 1 and 32 . 2 are embodied at an acute angle W of 85° with the lateral longitudinal surfaces 30 . 1 and 30 . 2 of the foot segment 20 . [0061] The head part 21 of the male end segment 16 has a mushroom head-shaped recess 38 that is for forming an inner undercut region 36 and that is embodied proceeding from the lateral head surfaces 33 . 1 and 33 . 2 of the extension parts 32 . 1 and 32 . 2 . The lateral head surfaces 33 . 1 and 33 . 2 transition to inner lateral longitudinal surfaces 40 . 1 and 40 . 2 for forming a sort of mushroom stem for the mushroom head-shaped recess 38 . The mushroom head of the mushroom head-shaped recess 38 has a lateral base surface 41 , some of which is linear and parallel to the base 22 and transitions into curved inner lateral surfaces 42 . 1 and 42 . 2 without any linear segments so that ultimately a mushroom head is formed. Minimum widths b 61 and b 62 of the extension parts 32 . 1 and 32 . 2 may be found in the region of the mushroom head-shaped recess 38 . [0062] FIG. 2 b depicts the female end segment 16 of the fastener 10 in which are shown the first and only outer transversal undercut region 27 , also cited with respect to the complementary embodiment to the male end segment 14 , and the innerly disposed transversal undercut region 36 . The first transversal undercut regions 26 and 27 extend from the minimum width b 1 of the foot segment 20 of the male end segment 14 to the minimum width b 21 or b 22 of longitudinal segments 50 . 1 and 50 . 2 of the female end segment 16 . The innerly disposed transversal undercut region 36 extends from a minimum width b 3 of a foot segment 56 of the female end segment 16 to the minimum widths b 61 and b 62 of the extension parts 32 . 1 and 32 . 2 of the male end segment 14 . Proceeding from a base 54 of the end segment 16 , a foot segment 56 with a head segment 57 is arranged approximately in the center. The foot segment 56 has a minimum width b 3 . Lateral longitudinal surfaces 58 . 1 and 58 . 2 of the length segment 56 transition from an obtuse angle β of approximately 95° into the base 54 . The foot segment 56 is thus embodied tapering towards the head part 57 . Connecting to the lateral longitudinal surfaces 58 . 1 and 58 . 2 of the length segment are lower lateral transverse surfaces 63 . 1 and 63 . 2 that are embodied at least in part parallel to the base 54 and transition to curved lateral surfaces 62 . 1 and 62 . 2 , which themselves transition to a lateral head surface 60 that is embodied with a center sub-region approximately parallel to the base 54 . In the transition between the lateral longitudinal surfaces 58 . 1 and 58 . 2 of the foot segment 56 and the lower lateral transverse surfaces 63 . 1 and 63 . 2 , radial regions 59 . 1 and 59 . 2 immediately following the minimum width b 3 have a notch radius of 0.8 mm and then tangentially continuously a notch radius of 0.3 mm. [0063] Length segments 50 . 1 and 50 . 2 , whose outer walls 51 . 1 and 51 . 2 transition flush into the outer wall 11 of the fastener 10 , are embodied on both sides of the mushroom head-shaped center formed by the foot segment 56 and the head part 57 . At its end that may be associated with the male end segment, the length segments 50 . 1 and 50 . 2 have recesses 53 . 1 and 53 . 2 in which extension segments 24 . 1 and 24 . 2 (see FIG. 2A ) of the male end segment 14 may engage. This provides a longitudinal undercut 28 (see FIG. 2A ). Projections 52 . 1 and 52 . 2 of the length segments 50 . 1 and 50 . 2 , associated with the male end segment 14 , come to be positioned therein in recesses 25 . 1 and 25 . 2 (see FIG. 2A ). [0064] The length segments 50 . 1 and 50 . 2 have minimum widths b 21 and b 22 . These minimum widths b 21 and b 22 follow second inner lateral transverse surfaces 65 . 1 and 65 . 2 within the undercut region 27 and are in the transition to the second inner lateral longitudinal surfaces 64 . 1 and 64 . 2 , wherein immediately connected to the minimum widths b 21 and b 22 is a notch radius of 0.8 mm and provided connected therein is a notch radius of 0.3 mm. The second inner lateral transverse surfaces 65 . 1 and 65 . 2 then transition into the first inner lateral transverse surfaces 66 . 1 and 66 . 2 . [0065] The ratio of the widths b 1 :(b 21 +b 22 +b 3 ) is approximately 0.87. With such a ratio, the minimum cross-sectional width of the male end segment 14 and the minimum cross-sectional widths of the female end segment 16 optimize the values for tensile stresses in the fastener once it has been closed to create a ring. [0066] The outer first undercut region 26 of the male end segment 14 comprises the lateral transverse surfaces 34 . 1 and 34 . 2 with connecting radial regions. According to FIG. 2B , the inner undercut region 36 is formed by the lower lateral transverse surfaces 63 . 1 and 63 . 2 and the radial regions connected thereto. [0067] FIG. 3 is a perspective elevation of the first example of the fastener 10 , shaped as a closed ring. In contrast, FIG. 4 is a top view onto a closed ring in a second example of the fastener 10 , the detail Y being shown in FIG. 6 . This second example is essentially similar to the first example according to FIGS. 1 through 3 , but the lateral longitudinal surfaces 35 . 1 and 35 . 2 of the extension parts 32 . 1 and 32 . 2 of the head part 21 are oriented exactly parallel to an outer wall 11 of the fastener 10 . In addition, an angle α, which is determined by the lateral transverse surfaces 34 . 1 and 34 . 2 and their linear segments on the one hand and, on the other hand, by a straight line running through the base 22 of the male end segment 14 or a parallel thereto, is 10° and not 5°, as in the example according to FIG. 2A . Consequently, in this example the value for the acute angle W, which is not shown in FIG. 12 , is approximately 80°, since the angle γ, which is also not shown in FIG. 12 , is 93°, just as in the first example according to FIG. 2A . However, the acute angle W may also be, for instance, 70° in an alternative to the example according to FIG. 12 . FIG. 12 provides an idealized view of the union of the male end segment 14 and the female end segment 16 on the fastener 10 that has been closed to create a ring. In fact, due to the use of bending tools there may be minor material deformations, however, so that the precise geometrical values, that is, the precise shape of the male and female end segments 14 , 16 in the closed ring, deviate somewhat from those of the open ribbon segment as shown in FIGS. 1 and 2 a/b. [0068] FIG. 5 depicts a third example of the inventive fastener 10 that has three stages of outer transversal undercut regions, wherein FIG. 7 illustrates a similarly embodied fifth example. In the region of a first base 22 of a male end segment 14 , the third example is similar to the male end segment 16 according to FIG. 2 a . A base 22 of the fifth example according to FIG. 7 is different from that of the third example in that there a material accumulation 74 . 1 and 74 . 2 is provided to a first male foot segment 20 . 1 , which material accumulation is more or less linearly increasing proceeding from the base 22 so that chamfering is formed. In the region of a first base 22 of a male end segment 14 , the third example is similar to the male end segment 16 according to FIG. 2A . The third example has in particular a first transversal undercut region 26 . 1 , a second transversal undercut region, 26 . 2 , and a third transversal undercut region 26 . 3 of the male end segment 14 , as well as a first transversal undercut region 27 . 1 , a second transversal undercut region 27 . 2 , and a third transversal undercut region 27 . 3 of the female end segment 16 . The third example, depicted in FIG. 5 , may be considered as (fir) tree-like. The cross-sectional width ratio of the first stage is calculated from the minimum width b 1 of the first male foot segment 20 . 1 and the minimum widths b 11 and b 12 of the extension segments 50 . 1 and 50 . 2 of the female end segment 16 (see also FIG. 7 ). It is approximately 1, and is likewise for the fifth embodiment according to FIG. 7 . The cross-sectional width ratio of the third stage, with respect to the third outer transversal undercut of the male end segment 14 and of the female end segment 16 , is calculated from the width b 2 of a third male foot segment 20 . 3 of the male end segment 14 and minimum widths b 21 and b 22 of the retention parts 50 . 1 and 50 . 2 of the female end segment 16 (b 2 :(b 21 +b 22 )). It is approximately 0.93, and is likewise for the fifth example according to FIG. 7 . [0069] FIG. 6 depicts a fourth example of an inventive fastener 10 that is the same as the sixth example according to FIG. 8 (see below, as well) apart from an inner undercut region 36 . This fourth example has a two-stage embodiment with transversal outer undercut regions 26 . 1 and 26 . 2 or 27 . 1 and 27 . 2 . A first transversal undercut region 26 . 1 of a male end segment 14 and a second transversal undercut region 27 . 2 of the female end segment 16 are provided, as is a first transversal undercut region 27 . 1 of a female end segment 16 and a second transversal undercut region 27 . 2 of the female end segment 16 . A cross-sectional width ratio on the second stage, calculated from a minimum width b 2 of a second male foot segment 20 . 2 and widths b 21 and b 22 from longitudinal segments 50 . 1 and 50 . 2 of the female end segment 16 in the region of the second transversal undercut 27 . 1 is approximately 1. A trough-like recess 48 is arranged in the male end segment 16 in the second head part. [0070] FIG. 8 depicts a sixth example of the inventive fastener 10 in the closed ring-shaped condition. In this example, two outer transversal undercut regions 26 . 1 and 26 . 2 of a male end segment and two outer transversal undercut regions 27 . 1 and 27 . 2 of the female end segment 16 are provided. The shape of the male end segment may be considered to be tree-like. The minimum width b 2 of a second male foot segment 20 . 2 in the second undercut region 26 . 2 is therefore used to determine for the ratio of the second stage b 2 :(b 21 +b 22 ), which is approximately 0.8, while for determining the cross-sectional width ratio on the first stage, a minimum width b 1 of a first male foot segment 20 . 1 in the first undercut region 26 . 1 is used and widths b 11 and b 12 of the outer lateral longitudinal segments 50 . 1 and 50 . 2 of the female end segment 16 in the undercut region 27 . 1 are used, as well as a minimum width b 3 of the inner undercut region 36 , and the ratio there b 1 :(b 11 +b 12 +b 3 ) is approximately 0.8. Because two outer undercut regions 26 . 1 and 26 . 2 are provided, the sixth example according to FIG. 8 has excellent values for static tensile elongation. Following the first undercut region 26 . 1 , then, a longitudinal undercut region is again provided due to the trough-like formation 44 , as is provided by the projections 24 . 1 and 24 . 2 in the first example according to FIG. 2 a , for instance. In addition, however, corresponding projections 24 . 1 and 24 . 2 are also provided on the base 22 . Otherwise the upper part with the recess 38 is identical to the second example according to FIGS. 4 and 12 . If there was a desire to provide two inner undercut regions, in a tree-like manner a recess 38 would be provided in the adjacent segment or a foot 20 . 1 would also be provided. [0071] FIG. 9 depicts a seventh example of the inventive fastener 10 that has first transversal undercut regions 26 . 1 and second transversal undercut regions 26 . 2 of the male end segment 14 and first transversal undercut regions 27 . 1 and second transversal undercut regions 27 . 2 of the female end segment 16 . On the second stage the cross-sectional width ratio, determined from a minimum width b 2 of a second male foot segment 20 . 1 and minimum widths b 21 and b 22 of longitudinal segments 50 . 1 and 50 . 2 of the female end segment 16 , is approximately 1, for the first stage the cross-sectional width ratio is approximately 0.91. The seventh example according to FIG. 9 has additional trough-like recesses 44 following the extension parts 32 . 1 and 32 . 2 and facing the second male foot segment 20 . 2 , though which is provided additional longitudinal undercuts and further improved meshing of the female end segment 16 with the male end segment 14 . The second head region of the male end segment 14 has a depression 82 , and at the base of this segment are arranged lengthening segments 80 . 1 and 80 . 2 in the form of small projections having a primarily curved outer contour that has a width b 5 of approximately 1.5 mm. These further improve meshing and make additional undercuts available. [0072] FIG. 10 depicts an eighth example of a fastener 10 similar to that shown in FIG. 9 . In particular the cross-sectional width ratios of the eighth example correspond to those of the seventh example according to FIG. 9 . However, the eighth example is different in the region of the first base 22 of the male end segment 14 . Similar to the first example according to FIG. 2A , provided in the male end segment 14 are lengthening segments 24 . 1 and 24 . 2 into which projections 52 . 1 and 52 . 2 of the longitudinal segments 50 . 1 and 50 . 2 of the female end segment 16 engage. [0073] FIG. 11 depicts a ninth example of the fastener 10 when closed, i.e., with male and female end segments, this example differing from, e.g., the first and second embodiments primarily in that the foot segment 56 of the female end segment 16 has been lengthened significantly, specifically beyond the base 22 of the male end segment 14 in the length direction of the fastener 10 . Because of this, the head part 57 is disposed on the far side of the base 22 so that then, ultimately, embodied in the male end segment 14 is a recess 38 that is displaced beyond the base 22 in the length direction of the fastener. In the embodiment according to FIG. 11 , the minimum width b 1 is formed by the two sub-widths b 11 and b 12 , so that there is a ratio (b 11 +b 12 ):(b 21 +b 22 +b 3 ) of 0.8. The widths b 11 and b 12 of the male end segment 16 then relate to the longitudinal segments 18 . 1 and 18 . 2 thereof, which were created due to the displacement of the recess 38 beyond the first base 22 in the length direction of the fastener. [0074] With the disclosed fastener, a fastener is provided that supplies better values in terms of tensile and bending load, so that ultimately crack openings are prevented during operation and the service life of the inventive fastener is thereby significantly extended.

A fastener, in particular for bellows, comprises a male end segment and a female end segment complementary to the male end segment. The fastener can be used to fasten bellows to joint housings and/or shafts, said fastener having improved closing behavior.

RELATED APPLICATION This application is a continuation of U.S. patent application Ser. No. 11/298,944 filed Dec. 12, 2005, which is incorporated herein by reference. BACKGROUND A. Field of the Invention Implementations consistent with the principles of the invention relate generally to information dissemination and, more particularly, to decentralized techniques for allowing web annotation. B. Description of Related Art The World Wide Web (“web”) contains a vast amount of information. When browsing a particular document on the web, such as a web page, users are typically limited to only viewing the web page itself. Supplementary information, such as information provided by other web sites or other web users about the particular site being viewed, can be difficult to easily view. For example, assume that a user is viewing the manufacturer's web page relating to a product the user is interested in purchasing. To see other web pages reviewing or commenting on the product, the user may need to separately search for other web sites pages that contain formal reviews or other comments about the product. One attempt to allow users to annotate particular web pages with comments that could be viewed by other users when visiting the web page was the “Third Voice” browser plug-in. Third Voice allowed users to post public notes about a web site that could then be seen by other Third Voices users that later visit the web site. One problem suffered by this product was that comments about a web site were often “low quality” comments that were spammy and/or inappropriate. SUMMARY One aspect is directed to a method that includes detecting when a user visits a web site; receiving, in response to the detection, a group of blog posts that link to the web site; and displaying an indication of the group of blog posts to the user while the user is visiting the web site. Another aspect is directed to a method including detecting when a user visits a web site and submitting, in response to the detection, a search query to a search engine. The search query requests documents relevant to the web site. The method further includes receiving documents in response to the submitted search query and displaying an indication of the documents to the user while the user is visiting the web site. Yet another aspect is directed to a system including a blog search engine and a client device connected to the blog search engine over a network. The client device includes a software component configured to display web sites to users and to concurrently determine and display portions of blog posts that link to a currently displayed web site. The blog posts are determined based on a query to the blog search engine for blog posts linking to the currently displayed web site. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, explain the invention. In the drawings, FIG. 1 is a diagram of an exemplary system in which concepts consistent with the principles of the invention may be implemented; FIG. 2 is a diagram of an exemplary client or server shown in FIG. 1 ; FIGS. 3A and 3B are diagrams of exemplary graphical user interfaces presented to a user by the DCom (“Distributed Web Comments”) component and browser shown in FIG. 1 ; FIG. 4 is a flowchart illustrating exemplary operations through which a user may initially install or configure the DCom component; FIG. 5 is a flow chart illustrating exemplary operations that may be performed during minimized operation of the DCom component; FIG. 6 is a flow chart illustrating exemplary operations that may be performed during operation of the DCom component; and FIGS. 7A-7D are diagrams of additional exemplary graphical user interfaces that may be presented to a user by the DCom component and the browser. DETAILED DESCRIPTION The following detailed description of the invention refers to the accompanying drawings. The detailed description does not limit the invention. Overview As described herein, an easy entry point is provided through which users may annotate web pages and see other users' annotations. The annotations may be taken from blog posts relating to the web page being annotated. A “blog,” which is a shortened term for weblog, may be defined as a website through which an individual or a group generates text, photographs, video, audio files, and/or links, typically but not always on a daily or otherwise regular basis. Authoring a blog, maintaining a blog or adding an article to an existing blog is called “blogging”. Individual articles on a blog are called “blog posts”, “posts”, or “entries”. The person who posts these entries is called a “blogger”. Frequently, bloggers generate posts that comment on and/or link to other web pages. Consistent with an aspect of the invention, a user viewing a web site may concurrently view blog posts about the web site. By using blog posts as annotation information for a web site, inappropriate or spammy comments about a web site can be reduced, as blog posts tend to have an inherent level of seriousness associated with them and the blog posts can be ranked or otherwise filtered based on the quality of the underlying blog. System Description FIG. 1 is an exemplary diagram of a system 100 in which concepts consistent with the principles of the invention may be implemented. System 100 may include clients 110 coupled to servers 120 and 122 via a network 140 . Network 140 may include a local area network (LAN), a wide area network (WAN), a telephone network, such as the Public Switched Telephone Network (PSTN), an intranet, the Internet, or a combination of networks. Two clients 110 and two servers 120 and 122 have been illustrated as connected to network 140 for simplicity. In practice, there may be more clients and/or servers. Also, in some instances, a client may perform the functions of a server and a server may perform the functions of a client. Clients 110 may include a device, such as a wireless telephone, a personal computer, a personal digital assistant (PDA), a lap top, or another type of computation or communication device, a thread or process running on one of these devices, and/or an object executable by one of these devices. Clients 110 may include software such as a browser 115 that is used to access and display web pages from a web server such as server 120 or 122 . Browser 115 may include, for example, the Firefox™ browser. Clients 110 may additionally include a software component designed to interact with browser 115 to allow users to annotate and view annotations relating to web pages. This software component will be referred to herein as DCom (Distributed Web Comments) component 118 . DCom component 118 may be, for example, in some implementations, a web browser plugin or extension. In other implementations, DCom component 118 may be a separate program on client 110 . Servers 120 and 122 may provide services on behalf of clients 110 , and may include, for example, a web server, a file server, or an application server. In one implementation, server 120 may include a search engine 125 usable by clients 110 . Search engine 125 may be a query-based document search engine. Search engine 125 may be designed to return links to web pages that include information relevant to a search query. Search engine 125 may be a specialized search engine, such as a blog search engine designed to return blog posts or links that are relevant to user's search query. Search engine 125 may respond to user search queries based on documents stored in database 135 . The documents stored in database 135 may include web pages that are connected to network 140 and that were previously crawled and indexed by search engine 125 . When search engine 125 is a blog search engine, the documents stored in database 135 may be indexed blog posts or blogs. Although shown as a single database in FIG. 1 , database 135 could be distributed over multiple storage devices. Similarly, although shown as a single device in FIG. 1 , servers 120 / 122 and search engine 125 may be implemented in a distributed manner over multiple computing devices. FIG. 2 is an exemplary diagram of a client 110 , server 120 , or server 122 , referred to as computing device 200 , according to an implementation consistent with the principles of the invention. Computing device 200 may include a bus 210 , a processor 220 , a main memory 230 , a read only memory (ROM) 240 , a storage device 250 , an input device 260 , an output device 270 , and a communication interface 280 . Bus 210 may include a path that permits communication among the components of computing device 200 . Processor 220 may include any type of processor, microprocessor, or processing logic that may interpret and execute instructions. Main memory 230 may include a random access memory (RAM) or another type of dynamic storage device that stores information and instructions for execution by processor 220 . ROM 240 may include a ROM device or another type of static storage device that stores static information and instructions for use by processor 220 . Storage device 250 may include a magnetic and/or optical recording medium and its corresponding drive. Input device 260 may include a mechanism that permits a user to input information to computing device 200 , such as a keyboard, a mouse, a pen, voice recognition and/or biometric mechanisms, etc. Output device 270 may include a mechanism that outputs information to the user, including a display, a printer, a speaker, etc. Communication interface 280 may include any transceiver-like mechanism that enables computing device 200 to communicate with other devices and/or systems. For example, communication interface 280 may include mechanisms for communicating with another device or system via a network, such as network 140 . Software components of system 100 , such as search engine 125 , browser 115 , and DCom component 118 may be stored in a computer-readable medium, such as memory 230 . A computer-readable medium may be defined as one or more physical or logical memory devices and/or carrier waves. The software instructions defining the software components may be read into memory 230 from another computer-readable medium, such as data storage device 250 , or from another device via communication interface 280 . The software instructions contained in memory 230 cause processor 220 to perform processes that will be described later. Alternatively, hardwired circuitry may be used in place of or in combination with software instructions to implement processes consistent with the present invention. Thus, implementations consistent with the principles of the invention are not limited to any specific combination of hardware circuitry and software. Operation of DCom Component 118 FIG. 3A is a diagram illustrating an exemplary graphical user interface 300 for a web browser 115 presented to a client 110 using DCom component 118 . User interface 300 may include menu section 305 , navigation toolbar 310 , a web page display section 315 , and a status bar 320 . Menu section 305 presents a number of menus to the user through which the user may control the operation of web browser 115 . Navigation toolbar 310 may include one or more controls through which the user can control web browser 115 when navigating the web, such as “forward” and “back” buttons and an input box to enter uniform resource locators (URLs). Web page display section 315 may present the web page currently being visited and status bar 320 may display status information relating to the operation of web browser 115 . Status bar 320 may additionally display an indication of how highly the web site or web page currently being visited (i.e., the site in display section 315 ) is annotated. In the example shown in FIG. 3A , this function is performed via a “buzz” icon 325 , which is illustrated as a graphical meter. Buzz icon 325 may be displayed in status bar 320 on behalf of or under the control of DCom component 118 . Buzz icon 325 may change based on a “buzz rating” determined based on the annotations associated with the current web site. For example, when a user is visiting a web site with no associated annotations, buzz icon 325 may not be shown or may be shown as an graphical bar or meter with an empty or zero reading. When a user is visiting a web site with annotations, buzz icon 325 may change to reflect the number, quality, and/or temporal relevance of the annotations. For example, a user visiting a site with a lot of annotations may see a buzz icon with a full meter reading. In some implementations, the size or color of buzz icon 325 may also change. The particular design used by buzz icon 325 to reflect the annotations for a site is not critical. In general, buzz icon 325 may be designed so that sites with a high “buzz” rating are given a “stronger” icon, where the buzz rating may be based on some combination of the number, quality, or timeliness of the annotations associated with the web site. In some implementations, timeliness of the annotations for a site may be based on timeliness relative to the last time the user visited a site. In other words, buzz icon 325 may indicate how much the annotations for the site have changed since the last time the user visited the site. Additionally, in some implementations, the functionality of buzz icon 325 may be presented to the user in sections of browser 115 other than status bar 320 . FIG. 3B is a diagram illustrating a second exemplary graphical user interface 350 for a web browser 115 presented to a client 110 using DCom component 118 . Graphical user interface 350 is similar to graphical user interface 300 , except that a sidebar 355 is additionally shown within web page display section 315 . Sidebar 355 may be displayed in response to the user indicating an interest in the annotations for a site. For example, the user may be able to toggle sidebar 355 by clicking on buzz icon 325 , by typing a specific keyboard combination, or by selecting the sidebar from menu 305 . Sidebar 355 may display the annotations, portions of the annotations, or links to the annotations associated with a particular site. Sidebar 355 may additionally allow the user to post comments to his/her blog about the site. As shown in the example of FIG. 3B , sidebar 355 displays portions of three blog posts, labeled as posts 360 - 362 , that link to the current web site. Each blog post 360 - 362 may include a link (i.e., the underlined portion), that, when selected by the user, may take the user to the web page corresponding to the selected blog post. Sidebar 355 may additionally include a “more” link 365 that, when selected, causes additional annotations to be shown, and a “create post” link 367 that, when selected, may provide a convenient entry point through which the user may create a blog post in their own blog about the web site. The operation of DCom component 118 in conjunction with browser 115 will next be described in more detail with reference to the flow charts shown in FIGS. 4-6 . FIG. 4 is a flowchart illustrating exemplary operations through which a user may initially install or configure DCom component 118 . The user may initially install DCom component 118 at client computer 110 at which DCom component 118 is to be used (act 401 ). DCom component 118 may be a browser plugin, extension, or other browser addon component that is downloaded from server 120 or 122 . In other implementations, DCom component 118 may be script or other code that can be downloaded and run by client 110 on an as-needed basis. In still other implementations, DCom component 118 may be a separate application that runs in parallel with browser 115 at client 110 . When initially running DCom component 118 , the user may be queried to determine whether they have a blog hosted at a site recognized by DCom component 118 (act 402 ). If yes, the user may enter their registration information, such as their username and password, for their blog (act 403 ). This information may be later used to allow the user to post or to begin a post from within sidebar 355 . If the user does not have a blog hosted at a site recognized by DCom component 118 , the user may be prompted to determine whether they would like to sign up for a new blog (act 404 ). If the user decides they would like to sign up for a new blog, a new web page may be opened at a registration page for the new blog. After the initial installation, login, and/or registration shown in acts 401 - 404 , DCom component 118 may execute normally on client 110 (act 405 ). Normal execution of DCom component 118 will be described in more detail below with reference to FIGS. 5 and 6 . After initial installation and registration, acts 401 - 403 may not need to be performed each time the user uses client 110 . FIG. 5 is a flow chart illustration exemplary operations that may be performed during minimized operation of DCom component 118 . DCom component 118 may monitor the browsing session of the user for changes to the web site or web page the user is viewing (act 501 ). When DCom component 118 detects a new site, or possibly, a new web page within a site, DCom component 118 may obtain the buzz rating, or information that can be used to obtain the buzz rating, for the site (acts 502 and 503 ). The buzz rating is designed to generally reflect the likelihood that a user will want to view the annotations for the site. As previously mentioned, the buzz rating may be based on some combination of the number, quality, or timeliness of the annotations associated with the web site. In one implementation, DCom component 118 may calculate the buzz rating based on the examination of the annotations (i.e., blog posts) that correspond to a site. The annotations may be obtained by querying a blog search engine, such as search engine 125 , in a manner that restricts the search results to blog posts that link to the current site. For example, queries to the existing Google™ blog search engine of the form “link: <URL>” restricts results to blog posts that link to “URL.” Using the example web site shown in FIG. 3A , DCom component may submit the query “link: labs.google.com”. The results of this query from search engine 125 may include a number of blog posts for this web site “labs.google.com”. Based on the number, timeliness, and/or quality of these blog posts, DCom component 118 may generate the buzz rating. As one example of generating a buzz rating, the buzz rating may be equal to the number of blog posts returned from search engine 125 that is more recent than a particular cut-off date (such as the date associated with the last time the user visited the site). The buzz rating calculated in act 503 may be presented to the user (act 504 ). For example, the buzz rating may be visually presented to the user via buzz icon 325 . As previously mentioned, buzz icon 325 may be designed so that sites with a high “buzz” rating are given a “stronger” (visually more distinctive) icon. FIG. 6 is a flow chart illustrating exemplary operations that may be performed during operation of DCom component 118 when the user is viewing the main user interface for DCom component 118 (e.g., when the user has clicked buzz icon 325 to display sidebar 355 ). DCom component 118 may retrieve the annotations, or links to the annotations, for the current site, such as by querying search engine 125 (act 601 ). The annotations may previously have been downloaded by DCom component 118 in generating the buzz rating ( FIG. 5 ). In this situation, DCom component 118 may not need to re-query search engine 125 . The annotations, or a pre-selected number of the annotations, may then be displayed to the user (act 602 ). In the example shown in FIG. 3B , three annotations for the current site are shown to the user in sidebar 355 . DCom component 118 may appropriately respond to user actions in sidebar 355 . For example, if the user clicks on a link associated with one of the annotations, browser 115 may be directed to display the complete blog or blog post corresponding to the annotation (act 603 ). In situations where more annotations are available, the user may choose to see more annotations in sidebar 355 , such as by selecting the “more” link 355 (act 604 ). Still further, the user may choose to post a comment about the current site by creating a post for their blog (act 605 ). The user may initiate their blog post by selecting “create post” link 367 . Doing so may, for example, take the user to a web page at which the user may manage the blog and, in particular, create a new post for the blog. The new blog post may be preset to include a link back to the current site (i.e., “labs.google.com” in the example shown in FIG. 3B ). Exemplary Additional User Interfaces As mentioned, the user interface shown in FIGS. 3A and 3B are exemplary. Additional exemplary user interfaces that may be provided by DCom component 118 will now be described with reference to FIGS. 7A-7D . In this exemplary implementation of DCom component 118 , DCom component 118 may communicate with the user through popup windows instead of through the sidebar shown in FIG. 3B . In some implementations, how DCom component 118 communicates with the user, such as a popup window or browser sidebar windows, may be a user-configurable parameter. FIG. 7A is a diagram illustrating an exemplary graphical user interface 700 for a web browser 115 presented to a client 110 using DCom component 118 . Graphical user interface 700 may include a buzz icon 725 that functions similarly to buzz icon 325 . Instead of sidebar 355 , graphical user interface 700 may include a popup window 755 that displays a number of annotations for the site currently being viewed. Popup window 755 may include a header link 760 for each annotation, a “show lots more” link 765 , and an “add comment” link 767 . Header link 760 , when selected by the user, may open a web browsing window at the blog post corresponding to the header. Show lots more link 765 and add comment link 767 may function similarly to “more” link 365 and “create post” link 367 , respectively. Specifically, show lots more link 765 , when selected, causes additional annotations for the web site, if available, to be displayed in popup window 755 . Add comment link 767 may provide a convenient entry point through which the user may create a blog post in their own blog about the web site. FIG. 7B is a diagram illustrating an exemplary graphical user interface 702 in which popup window 755 is shown as a smaller popup window. Users may switch between the larger version of popup window 755 and the smaller version of popup window 755 using standard sizing icons in the upper right corner of the window. FIG. 7C is a diagram illustrating an exemplary popup dialog 704 that may be provided to the user when the user selects “add comment” 767 link without having a registered blog. As shown, dialog 704 provides fields through which users may enter their blog username and password. Additionally, dialog 704 provides a link through which the user may register for a new blog and a link through which the user may recover a forgotten password. FIG. 7D is a diagram illustrating an exemplary dialog 706 that may be provided to the user when the user selects “add comment” link 767 and the user has registered their blog. As shown, dialog 706 provides an area 770 in which the user may compose their blog post. Area 770 may be pre-populated with a link back to the web page currently being viewed. In the example shown in FIG. 7D , this link is illustrated as the underlined text “Read . . . ”. When the user is ready to publish the blog post to his/her blog, the user may select “publish” button 772 . Although DCom component 118 was generally described above as receiving and operating on web annotations from a blog search engine, DCom component 118 may more generally operate to receive annotations from other search engines in which the search results are in someway limited by the site or web page currently being visited. More generally, DCom component 118 may operate to receive annotation information from any other website that links to and in someway comments on the current web site. The linking websites may include websites that in someway provide reviews, commentary, critiques, or feedback to the current website or webpage. Additionally, instead of receiving annotations from a search engine, DCom component 118 may receive the annotations from a different server, such as an annotation server designed to operate specifically with DCom component 118 . CONCLUSION Techniques for providing decentralized user web annotations were described above. The web annotations may be based on blog posts, providing the system with an existing initial base of web annotations. Additionally, because the annotations may be received from a blog search engine, which may already provide quality and/or spam filtering controls on the blogs it is indexing, the annotations are likely to be less spammy or inappropriate relative to existing web annotation systems. The foregoing description of exemplary embodiments of the invention provides illustration and description, but are not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. For example, while a series of acts have been described with regard to FIGS. 4-6 , the order of the acts may be varied in other implementations consistent with the invention. Moreover, non-dependent acts may be implemented in parallel. It will also be apparent to one of ordinary skill in the art that aspects of the invention, as described above, may be implemented in many different forms of software, firmware, and hardware in the implementations illustrated in the figures. The actual software code or specialized control hardware used to implement aspects consistent with the principles of the invention is not limiting of the invention. Thus, the operation and behavior of the aspects of the invention were described without reference to the specific software code—it being understood that one of ordinary skill in the art would be able to design software and control hardware to implement the aspects based on the description herein. Further, certain portions of the invention may be implemented as “logic” or as a “component” that performs one or more functions. This logic or component may include hardware, such as an application specific integrated circuit or a field programmable gate array, software, or a combination of hardware and software. No element, act, or instruction used in the description of the invention should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items. Where only one item is intended, the term “one” or similar language is used. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

Annotations relating to web sites may be based on blog posts relating to the web sites. A user viewing a web site may concurrently view related blog posts about the web site. More particularly, in one implementation, a method includes detecting when a user visits a web page and receiving, in response to the detection, a group of blog posts that link to the web page. The method further includes displaying an indication of the group of blog posts to the user while the user is visiting the web site.

This is a divisional application of U.S. Application Ser. No. 07/565,306 filed Aug. 9, 1990. BACKGROUND OF THE INVENTION Excessive excitation by neurotransmitters can cause the degeneration and death of neurons. It is believed that this degeneration is in part mediated by the excitotoxic actions of glutamate and aspartate at the N-methyl-D-aspartate (NMDA) receptor. This excitotoxic action is responsible for the loss of neurons in cerebrovascular disorders such as: cerebral ischemia or cerebral infraction resulting from a range of conditions such as thromboembolic or hemorrhagic stroke, cerebral vasospasm, hypoglycemia, cardiac arrest, status epilepticus, perinatal asphyxia, cerebral trauma and anoxia (such as from drowning and pulmonary surgery). There are no specific therapies for these neurodegenerative diseases, however, compounds which act specifically as antagonists of the NMDA receptor complex, either competitively or noncompetitively, offer a novel therapeutic approach to these disorders: R. Schwarcz and B. Meldrum, The Lancet 140 (1985); B. Meldrum in "Neurotoxins and Their Pharmacological Implications" edited by P. Jenner, Raven Press, New York (1987); D. W. Choi, Neuron 1:623 (1988). Confirmation of the protective effects of noncompetitve NMDA antagonists in various pharmacological models of neurodegenerative disorders have appeared in the literature: J. W. McDonald, F. S. Silverstein, and M. V. Johnston, Eur. J. Pharmocol. 140:359 (1987); R. Gill, A. C. Foster, and G. N. Woodruff, J. Neurosci. 7:3343 (1987); S. M. Rothman, J. H. Thurston, R. E. Hauhart, G. D. Clark, and J. S. Soloman, Neurosci. 21:673 (1987); M. P. Goldbert, P-C. Pham, and D. W. Choi, Neurosci. Lett. 80:11 (1987); L. F. Copeland, P. A. Boxer, and F. W. Marcoux, Soc. Neurosci. Abstr. 14 (part 1):420 (1988); J. A. Kemp, A. C. Foster, R. Gill, and G. N. Woodruff, TIPS 8:414 (1987); R. Gill, A. C. Foster, and G. N. Woodruff, J. Neurosci. 25:847 (1988); C. K. Park, D. G. Nehls, D. I. Graham, G. M. Teasdale, and J. M. McCulloch, Ann. Neurol. 24:543 (1988); G. K. Steinburg, C. P. George, R. DeLaPlaz, D. K. Shibata, and T. Gross, Stroke 19:1112 (1988); J. F. Church, S. Zeman, and D. Lodge, Anesthesiology 69:702 (1988). The compounds of the present invention are useful in the treatment of neurodegenerative disorders including cerebrovascular disorders. Such disorders include but are not limited to cerebral ischemia or cerebral infarction resulting from a range of conditions such as thromboembolic or hemorrhagic stroke, cerebral vasospasm, hypoglycemia, cardiac arrest, status epilepticus, perinatal asphyxia, cerebral trauma and anoxia such as from drowning and/or pulmonary surgery. Other treatments are for schizophrenia, epilepsy, spasticity, neurodegenerative disorders such as Alzheimer's disease or Huntington's disease, Olivo-pontocerebellar atrophy, spinal cord injury, and poisoning by exogenous NMDA poisons (e.g., some forms of lathyrism). Further uses are as analgesics and anesthetics, particularly for use in surgical procedures where a finite risk of cerebrovascular damage exists. SUMMARY OF THE INVENTION The present invention concerns compounds of the formula I ##STR1## or a pharmaceutically acceptable acid addition salt thereof wherein R 1 , R 2 , R 3 , m, and n are as described herein below. The present invention also includes a pharmaceutical composition comprising a therapeutically effective amount of a compound of formula I together with a pharmaceutically acceptable carrier. The present invention also includes a method for treating cerebrovascular disorders which comprises administering to a patient in need thereof the above pharmaceutical composition in unit dosage form. The present invention also includes a method of treating disorders responsive to the blockade of glutamic and aspartic acid receptors in a patient comprising administering a therapeutically effective amount of the above composition. The invention also includes a method for treating cerebral ischemia, cerebral infarction, cerebral vasospasm, hypoglycemia, cardiac arrest, status epilepticus, cerebral trauma, schizophrenia, epilepsy, neurodegenerative disorders, Alzheimer's disease, or Huntington's disease comprising administering to a patient in need thereof a therapeutically effective amount of the above composition. The invention also includes a method for treating stroke in patients in need thereof which comprises administering to a patient in need thereof a therapeutically effective amount of the above composition. The invention also includes using as an anesthetic the above composition in surgical operations where a risk of cerebrovascular damage exists. The invention further includes processes for the preparation of compounds of formula I. The invention still further includes novel intermediates useful in the processes. DETAILED DESCRIPTION The present invention concerns compounds of the formula ##STR2## or a pharmaceutically acceptable acid addition salt thereof wherein: R 1 is hydrogen, lower alkyl, lower alkenyl, lower alkynyl, arylloweralkyl, cyclopropylloweralkyl, or a pharmaceutically acceptable labile group; R 2 and R 3 are each independently hydrogen, lower alkyl, hydroxy, lower alkoxy, halogen, amino, monoloweralkylamino, diloweralkylamino; m is an integer of from 0 to 2; and n is an integer of from 2 to 4. Preferred compounds of the instant invention are those of formula I wherein: R 1 is hydrogen, lower alkyl, lower alkenyl, cyclopropylmethyl or arylloweralkyl; R 2 and R 3 are independently hydrogen, lower alkyl, hydroxy, or lower alkoxy; m is an integer of 0 or 1; n is 2 or 3; and indicates the ring is cis relative to its attachment at to the molecule. More preferred compounds of the instant invention are those of formula I wherein: R 1 is hydrogen, lower alkyl, cyclopropylmethyl, or arylloweralkyl; R 2 and R 3 are independently hydrogen, hydroxy, or lower alkoxy; m is an integer 0 or 1; and n is an integer 2 or 3. Still more preferred are compounds of formula I wherein: R 1 is hydrogen, methyl, ethyl, propyl, allyl, cyclopropylmethyl, or benzyl; R 2 and R 3 are each independently hydrogen, methoxy, or hydroxy; m is the integer 0 or 1; and n is the integer 2 or 3. Other more preferred compounds of the instant invention include: (+), (-), or (±)-2,3-Dihydro-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole, (+), (-), or (±)-2,3-Dihydro-7-methoxy-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole, (+), (-), or (±)-2,3-Dihydro-1-methyl-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole, (+), (-), or (±)-2,3-Dihydro-7-methoxy-1-methyl-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole, (+), (-) or (±)-2,3-Dihydro-7-methoxy-1-ethyl-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole, (+), (-), or (±)-2,3,4,5-tetrahydro-1-(2-propenyl)-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-3a,9b-butano-1H-benz[g]indol-8-ol, (+), (-), or (±)-2,3,4,5-Tetrahydro-1-methyl-3a,9b-butano-1H-benz[g]indol-8-ol, (+), (-), or (±)-2,3-Dihydro-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrol-7-ol, (+), (-), or (±)-2,3-Dihydro-1-methyl-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrol-7-ol, (+) (-), or (±)-1,2,3,4,5,6-Hexahydro-4a,10b-butanobenz[h]quinoline, (+), (-), or (±)-1,2,3,4,5,6-Hexahydro-9-methoxy-4a,10b-butanobenz[h]quinoline, (+), (-), or (±)-1,2,3,4,-Tetrahydro-4a,9b-butano-5H-indeno[1,2-b]pyridine, (+), (-) , or (±)-1,2,3,4,-Tetrahydro-8-methoxy-4a,9b-butano-5H-indeno[1,2-b]pyridine (+), (-), or (±)-1,2,3,4,5,6-Hexahydro-1-methyl-4a,10b-butanobenz[h]quinoline, (+), (-), or (±)-1,2,3,4,5,6-Hexahydro-9-methoxy-1-methyl-4a,10b-butanobenz[h]quinoline, (+), (-), or (±)-1,2,3,4,-Tetrahydro-1-methyl-4a,9b-butano-5H-indeno[1,2-b]pyridine, (+), (-), or (±)-1,2,3,4,-Tetrahydro-8-methoxy-1-methyl-4a,9b-butano-5H-indeno[1,2-b]pyridine, (+), (-), or (±)-1,2,3,4,5,6-Hexahydro-4a,10b-butanobenz[h]quinolin-9-ol, (+), (-), or (±)-1,2,3,4,5,6-Hexahydro-1-methyl-4a,10b-butanobenz[h]quinolin-9-ol, (+), (-), or (±)-1,2,3,4-Tetrahydro-1a,9b-butano-5H-indeno[1,2-b]pyridin-8-ol, and (+), (-), or (±)-1,2,3,4-Tetrahydro-1-methyl-4a,9b-butano-5H-indeno[1,2-b]pyridin-8-ol. Most preferred compounds of the instant invention are: (+), (-), or (±)-2,3,4,5-Tetrahydro-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-1-methyl-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-1-ethyl-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-1-propyl-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-1-(cyclopropylmethyl)-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-1-phenylmethyl-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-8-methoxy-3a,9b-butano-1H-benz[g]indole, (+), (-), or (±)-2,3,4,5-Tetrahydro-8-methoxy-1-methyl-3a,9b-butano-1H-benz[g]indole, and (+), (-), or (±)-2,3,4,5-Tetrahydro-8-methoxy-1-ethyl-3a,9b-butano-1H-benz[g]indole. Compounds of the instant invention include solvates, hydrates, and pharmaceutically acceptable salts of compounds of formula I above. The compounds of the present invention contain asymmetric carbon atoms. The instant invention includes the individual enantiomers, which may be prepared or isolated by methods known in the art. Any resulting racemates can be resolved into the optical antipodes by known methods, for example by separation of the diastereomeric salts thereof, with an optically active acid, and liberating the optically active amine compound by treatment with a base. Racemic compounds of the instant invention can thus be resolved into their optical antipodes e.g., by fractional crystallization of d- or 1- (tartarates, mandelates, or camphorsulfonate) salts. The compounds of the instant invention may also be resolved into the optical antipodes by the formation of diastereomeric carbamates by reacting the compounds of the instant invention with an optically active chloroformate, for example (-)-menthyl chloroformate, or by the formation of a diastereomeric amide by reacting the compounds of the instant invention with an optically active activated carboxy acid such as that derived from (+) or (-) phenylalanine, (+) or (-) phenylglycine, (-)-camphanic acid or the like. Additional methods for resolving optical isomers, known to those skilled in the art may be used, for example those discussed by J. Jaques, A. Collet, and S. Wilen in "Enantiomers, Racemates and Resolutions", John Wiley and Sons, New York (1981). The term lower in connection with organic groups, radical or compounds includes up to and including seven members, preferably up to and including four and most preferably one, two, or three carbon atoms except as otherwise specifically described. Lower alkyl means a straight or branched chain of from one to four carbon atoms including but not limited to methyl, ethyl, propyl, isopropyl, and butyl. Lower alkenyl means a group from one to four carbon atoms, for example, but not limited to ethylene, 1,2- or 2,3-propylene, 1,2- 2,3-, or 3,4-butylene. Preferred is 2,3-propylene. Lower alkynyl means a group from one to four carbon atoms, for example, but not limited to ethynyl, 2,3-propynyl, 2,3-, or 3,4-butynyl; propynyl is the preferred group. Cyclopropylloweralkyl means cyclopropyl-C 1-4 -alkyl, meaning for example, cyclopropylmethyl, 2-(cyclopropyl)ethyl, 3-(cyclopropyl)propyl; cyclopropylmethyl is the preferred group. Lower alkoxy means a group of from one to four carbon atoms, for example, but not limited to methoxy, ethoxy, propoxy; methoxy is the preferred group. Halogen is fluorine, chlorine, bromine, or iodine; fluorine, chlorine, and bromine are the preferred groups. Arylloweralkyl means aryl-C 1-4 -alkyl, meaning for example, benzyl, 2-phenylethyl, 3-phenylpropyl; preferred group is benzyl. The aryl groups may be substituted, for example, by lower alkyl, lower alkoxy, hydroxy, and halogen. Monoloweralkylamino means a group containing from one to four carbon atoms, for example, but not limited to methylamino, ethylamino, n- or i-(propylamino or butylamino). Diloweralkylamino means a group containing from one to four carbon atoms in each lower alkyl group, for example, but not limited to dimethylamino, diethylamino, di-(n-propyl)-amino, di-(n-butyl)-amino, or may represent a fused ring, for example piperidine. Physiologically labile group includes but is not limited to such derivatives described by; I. H. Pitman in Med. Chem. Rev. 2:189 (1981); J. Alexander, R. Cargill, S. R. Michelson and H. Schwam in J. Med. Chem. 31:318 (1988); V. H. Naringrekar and V. J. Stella in European Patent Application 214,009-A2 and include certain amides, such as amides of amino acids, for example glycine, or serine, enaminone derivatives and (acyloxy)alkylcarbamates. Well-known protecting groups and their introduction and removal are described, for example, in J. F. W. McOmie, Protective Groups in Organic Chemistry, Plenum Press, London, New York (1973), and T. W. Greene, Protective Groups in Organic Synthesis, Wiley, New York (1981). Salts of the compounds of the invention are preferably pharmaceutically acceptable salts. The compounds of the invention are basic amines from which acid addition salts of pharmaceutically acceptable inorganic or organic acids such as strong mineral acids, for example, hydrohalic, e.g., hydrochloric or hydrobromic acid; sulfuric, phosphoric or nitric acid; aliphatic or aromatic carboxylic or sulfonic acids, e.g., acetic, propionic, succinic, glycolic, lactic, malic, tartaric, gluconic, citric, ascorbic, maleic, fumaric, pyruvic, pamoic, nicotinic, methanesulfonic, ethanesulfonic, hydroxyethanesulfonic, benzenesulfonic, p-toluenesulfonic, or napthlenesulfonic acid can be prepared. For isolation or purification purposes, salts may be obtained which might not be useful for pharmaceutical purposes. Pharmaceutically acceptable salts useful for therapeutic purposes are preferred. The present invention also includes processes for making the compounds of formula I above. One process for the preparation of compounds of formula I is illustrated in Scheme A below. ##STR3## Step (1) The compound of formula II wherein m is 0 or 1 ##STR4## and R 2 and R 3 are as previously defined are treated with 1,4-dibromobutane under conditions described in Bull. Soc. Chim. France 346 (1957) to give the compounds of the formula III. ##STR5## Step (2) The compounds of the formula III are treated with lithioacetonitrile, in a solvent such as ether, tetrahydrofuran, or the like, at a temperature between -78° C. and 20° C. to afford the compounds of the formula IV. ##STR6## Step (3) The compounds of the formula IV are hydrogenated in the presence of a catalyst such as Raney Nickel, or the like, in a solvent such as methanol or ethanol containing ammonia, under a hydrogen atmosphere to give the compounds of the formula V wherein n is 2. ##STR7## Step (4) Alternatively, the compounds of the formula III are treated with a compound of the formula VI ##STR8## under conditions described by Evans et al in J. Amer. Chem Soc. 371, (1979) or by other methods known to those skilled in the art, such as those described in Tetrahedron 205, (1983) to give the compounds of the formula VII. ##STR9## Step (5) The compounds of the formula VII are treated with ammonia in a solvent such as toluene, tetrahydrofuran, or the like to give the compounds of the formula VIII. ##STR10## Step (6) The compounds of the formula VIII are reduced using lithium aluminum hydride, diborane, or the like, in a solvent such as ether, tetrahydrofuran, or the like to give the compounds of the formula V wherein n is 3. Step (7) The compounds of the formula V are treated with methyl chloroformate, ethyl chloroformate, 2,2,2-trichloroethyl chloroformate or an optically active chloroformate, for example (-)-menthyl chloroformate, (-)-α-methylbenzyl chloroformate or the like, in the presence of a trialkylamine such as triethylamine, tributylamine, diisopropylethylamine or the like, in a solvent such as dichloromethane, chloroform, or the like, to give the compounds of the formula IX wherein R 5 is methyl, ethyl, 2,2,2-trichloroethyl, (-)-menthol, (-)-α-methylbenzyl, or other acid stable protecting group. ##STR11## Step (8) The compounds of the formula IX are treated with acetic acid, formic acid, triflouroacetic acid, sulfuric acid or the like or combinations thereof, preferably combinations of acetic acid and sulfuric acid to give the compounds of the formula X ##STR12## Step (9) The compounds of the formula X are treated to remove the carbamate functionalitity using methods known to those skilled in the art for example wherein R 5 is 2,2,2-trichloroethyl the compounds are treated with zinc dust in methanol, ethanol or the like, in the presence of acetic acid, to afford the compounds of the formula I wherein n is 2 or 3, m is 0 or 1, R 1 is hydrogen and R 2 and R 3 are as previously defined. Step (10) The compounds of the formula I wherein R 1 is hydrogen are treated with an aldehyde such as formaldehyde, acetaldehyde, benzaldehyde or the like or with a ketone such as acetone, acetophenone, or the like, in the presence of a reducing agent such as sodium cyanoborohydride or the like, in a solvent such as methanol, ethanol or the like to give the compounds of the formula I wherein n is 2 or 3, m is 0 or 1, R 1 is as previously defined excepting hydrogen, and R 2 and R 3 are as previously defined. Step (11) Alternatively the compounds of the formula X are reduced in the presence of lithium aluminum hydride, diborane or the like, in a solvent such as ether, tetrahydrofuran or the like, to afford the compound of the formula I wherein R 1 is methyl. Novel intermediates useful in the preparation of compounds of formula I are: Spiro[cyclopentane-1,1'-[1H]inden]-2'(3'H)-one, 7,-methoxy-spiro[cyclopentane-1,1'-[1H]inden]-2'(3'H)-one, (+), (-), or (±)-3',4'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-napthalen]-2'-acetonitrile, (+), (-), or (±)-3',4'-dihydro-2'-hydroxy-7'-methoxyspiro[cyclopentane-1,1'(2'H)-napthalen]-2'-acetonitrile, (+), (-), or (±)-2',3'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'-[1H]inden]-2'-acetonitrile, (+), (-), or (±)-2',3'-Dihydro-2'-hydroxy-6-methoxyspiro[cyclopentane-1,1'-[1H]inden]-2'-acetonitrile, (+), (-), or (±)-2'-(2-aminoethyl)-3',4'-dihydrospiro[cyclopentane-1,1'(2H)-napthalen]-2'-ol, (+), (-), or (±)-2'-(2-aminoethyl)-3',4'-dihydro-7'-methoxyspiro[cyclopentane-1,1'(2'H)-napthalen]-2'-ol, (+), (-), or (±)-2'-(2-aminoethyl)-2',3',-dihydrospiro[cyclopentane-1,1'-[1H]inden-2'-ol, (+), (-), or (±)-2'-(2-aminoethyl)-2',3'-dihydro-6'-methoxyspiro[cyclopentane-1,1'-[1H]inden-2'-ol, Ethyl (+), (-), or (±)-[2-(3',4'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-napthalen]-2'yl)ethyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-[2-(3',4'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-naphthalen]-2'-yl)ethyl]carbamate, (+), (-, ) or (±)-2,2,2-Trichloroethyl-[2-(3',4'-dihydro-2'-hydroxy-7'-methoxyspiro[cyclopentane-1,1'(2'H)-naphthalen]-2'-yl)ethyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-[2-[2',3'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'-[1H]inden]-2'-yl)ethyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-[2-2',3'-dihydro-2'-hydroxy-6'-methoxyspiro[cyclopentane-1,1'-[1H]inden]-2'-yl)ethyl]carbamate, Ethyl (+), (-), or (±)-2,3,4,5-tetrahydro-3a,9b-butano-1H-benz[g]indole-1-carboxylate, (+), (-), or (±)-2,2,2-Trichloroethyl-2,3,4,5-tetrahydro-3a,9b-butano-1H-benz[g]indole-1-carboxylate, (+), (-), or (±)-2,2,2-Trichloroethyl-2,3,4,5-tetrahydro-8-methoxy-3a,9b-butano-1H-benz[g]indole-1-carboxylate, (+), (-), or (±)-2,2,2-Trichloroethyl-2,3-dihydro-1H,4H-3a,8b-butanoindeno-[1,2-b]pyrrole-1-carboxylate, (+), (-), or (±)-2,2,2-Trichloroethyl-2,3-dihydro-7-methoxy-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole-1-carboxylate, (+), (-), or (±)-3',3",4',4"Tetrahydrodispiro[cyclopentane-1,1'(2'H)-napthlene-2',2"(5"H)-furan]-5"-one, (+), (-), or (±)-3',3",4',4"-Tetrahydro-7'-methoxydispiro[cyclopentane-1,1'(2'H)-napthlene-2',2"(5"H)-furan]-5"-one, (+), (-), or (±)-3",4"-Dihydrodispiro-[cyclopentane-1,1'-[1H]indene-2'(3'H),2"(5"H)furan]-5"-one, (+), (-), or (±)-3",4"-Dihydro-6'-methoxydispiro[cyclopentane-1,1'-[1H]indene-2'(3'H),2"(5"H)furan]-5"-one, (+), (-), or (±)-3',4'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-naphthalene]-2'-propanamide, (+), (-), or (±)-3',4'-Dihydro-2'-hydroxy-7'methoxyspiro[cyclopentane-1,1'(2'H)-naphthalene]-2'-propanamide, (+), (-), or (±)-2',3',-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'-[1H]indene]-2'-propanamide, (+), (-), or (±)-2',3'-Dihydro-2'-hydroxy-6'-methoxyspiro[cyclopentane-1,1'-[1H]indene]-2'-propanamide, (+), (-), or (±)-2'-(3-aminopropyl)-3',4'-dihydrospiro[cyclopentane-1,1'(2'H)napthalen]-2'-ol, (+), (-), or (±)-2'-(3-aminopropyl)-3',4'-dihydro-7'-methoxyspiro[cyclopentane-1,1'(2'H)napthalen]-2'-ol, (+), (-), or (±)-2'-(3-aminopropyl)-2',3'-dihydrospiro[cyclopentane-1,1'-[1H]inden]-2'-ol , (+), (-), or (±)-2'-(3-aminopropyl)-2',3'-dihydro-6'-methoxyspiro[cyclopentane-1,1'-[1H]inden]-2'-ol, (+), (-), or (±)-2,2,2-Trichloroethyl-[3-(3',4'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-napthlene]-2'-yl)propyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-[3-(3',4'-dihydro-2'-hydroxy-7'-methoxyspiro[cyclopentane-1,1'(2'H)-napthlene]-2'-yl)propyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-[3-(2',3'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'-[1H]inden]-2'-yl)propyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-[3-(2',3'-dihydro-2'-hydroxy-6'-methoxyspiro[cyclopentane-1,1'-[1H]inden]-2'-yl)-propyl]carbamate, (+), (-), or (±)-2,2,2-Trichloroethyl-3,4,5,6-tetrahydro-4a,10b-butanobenz[h]quinoline-1(2H)-carboxylate, (+), (-), or (±)-2,2,2-Trichloroethyl-3,4,5,6-tetrahydro-9-methoxy-4a,10b-butanobenz[h]quinoline-1(2H)-carboxylate, (+), (-), or (±)-2,2,2-Trichloroethyl-3,4-dihydro4a,9b-butano-5H-indeno[1,2-b]pyridine-1(2H)-carboxylate, and (+), (-), or (±)-2,2,2-Trichloroethyl-3,4-dihydro-8-methoxy-4a,9b-butano-5H-indeno[1,2-b]pyridine-1(2H)-carboxylate. The compounds of the instant invention exhibit valuable pharmacological properties by selectively blocking the N-methyl-D-aspartate sensitive excitatory amino acid receptors in mammals. The compounds are thus useful for treating diseases responsive to excitatory amino acid blockade in mammals. The effects are demonstrable in in vitro tests or in vivo animal tests using mammals or tissues or enzyme preparations thereof, e.g., mice, rats, or monkeys. The compounds are administered enterally or parenterally, for example, orally, transdermally, subcutaneously, intravenously, or intraperitoneally. Forms include but are not limited to gelatin capsules, or aqueous suspensions or solutions. The applied in vivo dosage may range between about 0.01 to 100 mg/kg, preferably between about 0.05 and 50 mg/kg, most preferably between about 0.1 and 10 mg/kg. The ability of the compounds of the instant invention to interact with phencyclidine (PCP) receptors which represents a noncompetitive NMDA antagonist binding site, is shown by Examples 23 and 27 which bind with an affinity of less than 10 μM. Tritiated 1-[1-(2-thienyl)cyclohexyl]pipiridine (TCP) binding, designated RBS1, was carried out essentially as described in J. Pharmacol. Exp. Ther. 238, 739 (1986). For medical use, the amount required of a compound of formula I or pharmacologically acceptable salt thereof--(hereinafter referred to as the active ingredient) to achieve a therapeutic effect will, of course, vary both with the particular compound, the route of administration and the mammal under treatment and the particular disorder or disease concerned. A suitable systemic dose of a compound of formula I or pharmacologically acceptable salt thereof for a mammal suffering from, or likely to suffer from any condition as described herein before is in the range 0.01 to 100 mg of base per kilogram body weight, the most preferred dosage being 0.05 to 50 mg/kg of mammal body weight. It is understood that the ordinarily skilled physician or veterinarian will readily determine and prescribe the effective amount of the compound for prophylactic or therapeutic treatment of the condition for which treatment is administered. In so proceeding, the physician or veterinarian could employ an intravenous bolus followed by intravenous infusion and repeated administrations, parenterally or orally, as considered appropriate. While it is possible for an active ingredient to be administered alone, it is preferable to present it as a formulation. Formulations of the present invention suitable for oral administration may be in the form of discrete units such as capsules, cachets, tablets, or lozenges, each containing a predetermined amount of the active ingredient; in the form of a powder or granules; in the form of a solution or a suspension in an aqueous liquid or nonaqueous liquid; or in the form of an oil-in-water emulsion or a water-in-oil emulsion. The active ingredient may also be in the form of a bolus, electuary, or paste. A tablet may be made by compressing or molding the active ingredient optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing, in a suitable machine, the active ingredient in a free-flowing form such as a powder or granules, optionally mixed with a binder, lubricant, inert diluent, surface active, or dispersing agent. Molded tablets may be made by molding, in a suitable machine, a mixture of the powdered active ingredient and a suitable carrier moistened with an inert liquid diluent. Formulations suitable for parenteral administration conveniently comprise a sterile aqueous preparation of the active ingredient which is preferable isotonic with the blood of the recipient. Formulations suitable for nasal or buccal administration (such as self-propelling powder dispensing formulations described hereinafter), may comprise 0.1 to 20% w/w, for example, 2% w/w of active ingredient. The formulations, for human medical use, of the present invention comprise an active ingredient in association with a pharmaceuticaly acceptable carrier therefor and optionally other therapeutic ingredient(s). The carrier(s) must be `acceptable` in the sense of being compatible with the other ingredients of the formulations and not deleterious to the recipient thereof. So the pharmacologically active compounds of the invention are useful in the manufacture of pharmaceutical compositions comprising an effective amount thereof in conjunction or admixture with excipients or carriers suitable for either enteral or parenteral application. Preferred are tablets and gelatin capsules comprising the active ingredient together with a) diluents, e.g. lactose, dextrose, sucrose, mannitol, sorbitol, cellulose, and/or glycine; b) lubricants, e.g. silica, talcum, stearic acid, its magnesium or calcium salt, and/or polyethyleneglycol; for tablets also c) binders e.g. magnesium aluminum silicate, starch paste, gelatin, tragacanth, methylcellulose, sodium carboxymethylcellulose and/or polyvinylpyrrolidone; if desired d) disintegrants, e.g. starches, agar, alginic acid, or its sodium salt, or effervescent mixtures; and/or e) absorbents, colorants, flavors, and sweeteners. Injectable compositions are preferably aqueous isotonic solutions or suspensions, and suppositories are advantageously prepared from fatty emulsions, or suspensions. Said compositions may be sterilized and/or contain adjuvants, such as preserving, stabilizing, wetting or emulsifying agents, solution promoters, salts for regulating the osmotic pressure, and/or buffers. In addition, they may also contain other therapeutically valuable substances. Said compositions are prepared according to conventional mixing, granulating, or coating methods, respectively, and contain about 0.1 to 75%, preferably about 1 to 50%, of the active ingredient. The formulations may conveniently be presented in unit dosage form and may be prepared by any of the methods well-known in the art of pharmacy. All methods include the step of bringing the active ingredient into association with the carrier which constitutes one or more accessory ingredients. In general, the formulations are prepared by uniformly and intimately bringing the active ingredient into association with a liquid carrier or a finely divided solid carrier or both, and then, if necessary, shaping the product into the desired formulation. The following examples are illustrative of the present invention but are not intended to limit it in any way. EXAMPLE 1 ##STR13## 3',4'-Dihydrospiro[cyclopentane-1,1'(2'H)-napthlen]-2'-one A suspension of KOt-Bu (76.3 g, 0.68 mol) in 500 mL of xylene was treated dropwise with 2-tetralone (50 g, 0.34 mol). The resulting solution was treated dropwise with 1,4-dibromobutane (74.0 g, 0.34 mol) (exothermic reaction). The resulting suspension was heated to reflux for 18h. The reaction mixture was treated with water (200 mL) and the organic phase was collected. The aqueous phase was extracted with ethyl acetate (2×200 mL) and the combined organic extracts were dried (MgSO 4 ), filtered and concentrated. Distillation of the residue provided the product (65.6 g, 96%) as a colorless liquid. EXAMPLE 2 ##STR14## 3',4'-Dihydro-7'-methoxyspiro-8 cyclopentane-1,1'(2'H)-napthlen]-2'-one In a manner similar to that described in Example 1, 7-methoxy-2-tetralone (20.0 g, 0.113 mol) was converted to the title compound (10.3 g, 40%) as a colorless oil. EXAMPLE 3 ##STR15## Spiro[cyclopentane-1,1'-[1H]inden]-2'(3'H)-one In a manner similar to that described in Example 1, 2-indanone is converted to the title compound. EXAMPLE 4 ##STR16## 6'-Methoxy-spiro[cyclopentane-1,1'-[1H]inden]-2'(3'H)-one In a manner similar to that described in Example 1, 5-methoxy-2-indanone is converted to the title compound. EXAMPLE 5 ##STR17## (±)-3',4'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-napthalen]-2'-acetonitrile A solution of acetonitrile (1.1 g, 27.5 mmol) in 100 mL of anhydrous tetrahydrofuran (THF) was cooled to -78° C. and treated with lithium diisopropylamide (18 mL of a 1.5 M solution in tetrahydrofuran). The resulting suspension was stirred at -78° C. for 30 minutes and treated dropwise with a solution of the product from Example 1 (5.0 g, 24.9 mmol) in 10 mL of anhydrous THF. The resulting solution was warmed to room temperature and saturated aq. NH 4 Cl solution (15 mL) was added. The organic phase was collected and the aqueous phase was extracted with ether (3×50 mL). The combined organic phases were dried (MgSO 4 , filtered and concentrated. The solid which formed was suspended in diisopropyl ether and collected by suction filtration. The material was dried under vacuum to give the title compound (4.14 g, 69%) as a white solid mp 165°-166° C. Anal. (C 16 H 19 NO) Calc'd: C, 79.63; H, 7.94; N, 5.80 Found: C, 79.72; H, 7.86; N, 5.81 EXAMPLE 6 ##STR18## (±)-3',4'-Dihydro-2, hydroxy-7'-methoxyspiro[cyclopentane-1,1'(2'H)-napthalen]-2'-acetonitrile In a manner similar to that described in Example 5, the product of Example 2 (10.0 g, 43.4 mmol) was converted to the title compound (4.33 g, 37%) as a tan solid mp 126°-127° C. Anal. (C 17 H 21 NO 2 ) Calc'd C, 75.25; H, 7.80; N, 5.16 Found: C, 75.36; H, 7.67; N, 4.94 EXAMPLE 7 ##STR19## (±)-2',3'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'-[1H]inden]-2'-acetonitrile In a manner similar to that described in Example 5, the product of Example 3 is converted to the title compound. EXAMPLE 8 ##STR20## (±)-2',3'-Dihydro-2'-hydroxy-6-methoxyspiro[cyclopentane-1,1'-[1H]inden]-2'-acetonitrile In a manner similar to that described in Example 5, the product of Example 4 is converted to the title compound. EXAMPLE 9 ##STR21## (±)-2'-(2-Aminoethyl)-3',4'-dihydrospiro[cyclopentane-1,1'(2'H)-napthalen]-2'-ol A solution of the product from Example 5 (2.50 g, 10.3 mmol) in 100 mL of methanolic ammonia was hydrogenated over Raney nickel (2.0 g) at 52 psi for 7.5 hours. The reaction mixture was filtered to remove the catalyst and the filtrate concentrated to give the title compound (2.59 g, quantitative) as a pale green solid mp 107°-109° C. Anal. (C 16 H 23 NO) Calc'd: C, 79.63; H, 7.94; N, 5.81 Found: C, 79.37; H, 8.02; N, 5.59 EXAMPLE 10 ##STR22## (±)-2'-(2-Aminoethyl)-3',4'-dihydro-7'-methoxyspiro[cyclopentane-1,1(2'H)-napthalen]-2'-ol In a manner similar to that described for Example 9, the product of Example 6 (4.85 g, 17.9 mmol) was hydrogenated to give the title compound (4.86 g, 99%) as a pale green solid. Anal. (C 17 H 25 NO 2 ) Calc'd: C, 74.14; H, 9.15; N, 5.08 Found C, 73.40; H, 9.19; N, 5.04 EXAMPLE 11 ##STR23## (±)-2'-(2-Aminoethyl)-2',3'-dihydrospiro[cyclopentane-1,1'-[1H]inden-2'-ol In a manner similar to that described for Example 9, the product of Example 7 is hydrogenated to give the title compound. EXAMPLE 12 ##STR24## (±)-2'-(2-Aminoethyl)-2',3'-dihydro-6'-methoxyspiro-[cyclopentane-1,1'-[1H]inden-2'-ol In a manner similar to that described for Example 9, the product of Example 8 is hydrogenated to give the title compound. EXAMPLE 13 ##STR25## Ethyl (±)-[2-(3',4'-dihydro-2'-hydroxyspiro-[cyclopentane-1,1'(2'H)-napthalen]-2'-yl)ethyl]-carbamate A solution of the product from Example 9 (1.05 g, 4.28 mmol) and triethylamine (0.44 g, 4.35 mmol) in 10 mL of CH 2 Cl 2 was cooled to 0° C. and ethyl chloroformate (0.47 g, 4.33 mmol) in 5 mL CH 2 Cl 2 was added dropwise. The reaction was warmed to room temperature and washed with water. The aqueous phase was extracted with CH 2 Cl 2 (3×20 mL) and the combined organic extracts were dried (MgSO 4 ), filtered and concentrated. The residue was purified by chromatography (silica gel, 1:1 heptane/ethyl acetate) to give the title compound (1.33 g, 98%) as an oil. EXAMPLE 14 ##STR26## 2,2,2-Trichloroethyl (±)-[2-(3',4'-dihydro-2'-hydroxyspiro-8 cyclopentane-1,1'(2'H)-naphthalen]-2'yl)ethyl]carbamate A solution of the product from Example 9 (0.88 g, 3.59 mmol) and triethylamine (0.40 g, 3.78 mmol) in 10 mL of CH 2 Cl 2 was cooled to 0° C. and treated dropwise with 2,2,2-trichloroethylchloroformate (0.80 g, 3.78 mmol) in 2 mL CH 2 Cl 2 . The resulting solution was stirred at 0° C. for 30 minutes and warmed to room temperature. The reaction mixture was washed with saturated aq. NaHCO 3 solution (10 mL). The aqueous phase was extracted with CH 2 Cl 2 (10 mL). The combined organic extracts were dried (MgSO 4 ), filtered and concentrated. The residue was purified by chromatography (silica gel, 10:1 heptane/ethyl acetate) to give the title compound (1.18 g, 78%) as a viscous oil. EXAMPLE 15 ##STR27## 2,2,2-Trichloroethyl (±)-[2-(3',4'-dihydro-2'-hydroxy-7'-methoxyspiro[cyclopentane-1,1'(2'H)-naphthalen]-2'-yl)ethyl]carbamate In a manner similar to that described in Example 14, the product of Example 10 (4.66 g, 16.9 mmol) is converted to the title compound (6.81 g, as a foamy white solid. EXAMPLE 16 ##STR28## 2,2,2-Trichloroethyl (±)-[2-[2',3'-dihydro-2'-hydroxy-spiro[cyclopentane-1,1'-[1H]inden]-2'-yl)ethyl]carbamate In a manner similar to that described in Example 14, the product of Example 11 is converted to the title compound. EXAMPLE 17 ##STR29## 2,2,2-Trichloroethyl (±)-[2-[2',3'-dihydro-2'-hydroxy-6'-methoxyspiro[cyclopentane-1,1'-[1H]inden]-2'-yl)ethyl]carbamate In a manner similar to that described in Example 14, the product of Example 12 is converted to the title compound. EXAMPLE 18 ##STR30## Ethyl (±)-2,3,4,5-tetrahydro-3a,9b-butano-1H-benz[g]indole-1-carboxylate A solution of the product from Example 13 (1.68 g, 5.29 mmol) in 15 mL of 3:1 acetic acid/concentrated sulfuric acid (v/v) was stirred at room temperature for 18 hours. The reaction mixture was poured into water (50 mL) and the resulting mixture was extracted with CH 2 Cl 2 (4×30 mL). The combined organic extracts were dried (MgSO 4 ), filtered and concentrated. The residue was dissolved in CH 2 Cl 2 (100 mL and washed with saturated aq. bicarbonate solution (30 mL). The organic phase was dried (MgSO 4 ), filtered and concentrated. The residue was purified by chromatography (silica gel, 9:1 heptane/ethyl acetate) to give the title compound (0.94 g, 59%) as a white solid mp 67°-69° C. Anal. (C 19 H 25 NO 2 ) Calc'd: C, 76 22; H, 8.42; N, 4.68 Found: C, 75.99; H, 8.38; N, 4.41 EXAMPLE 19 ##STR31## 2,2,2-Trichloroethyl (±)-2,3,4,5-tetrahydro-3a,9b-butano-1H-benz[g]indole-1-carboxylate In a manner similar to that described in Example 18, the product of Example 14 (0.98 g, 2.33 mmol) was converted to the title compound (0.71 g, 76%) as an oil. EXAMPLE 20 ##STR32## 2,2,2-Trichloroethyl (±)-2,3,4,5-tetrahydro-8-methoxy-3a,9b-butano-1H-benz[g]indole-1-carboxylate In a manner similar to that described in Example 18, the product of Example 15 (5.16 g, 11.4 mmol) was converted to the title compound (4.18 g, 84%) as an oil. EXAMPLE 21 ##STR33## 2,2,2-Trichloroethyl (±)-2,3-dihydro-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole-1-carboxylate In a manner similar to that described in Example 18, the product of Example 16 is converted to the title compound. EXAMPLE 22 ##STR34## 2,2,2-Trichloroethyl (±)-2,3-dihydro-7-methoxy-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole-1-carboxylate In a manner similar to that described in Example 18, the product of Example 17 is converted to the title compound. EXAMPLE 23 ##STR35## (±)-2,3,4,5-Tetrahydro-3a,9b-butano-1H-benz[g]indole hydrochloride A solution of the product from Example 19 (0.70 g, 1.74 mmol) in 20 mL of methanol and 0.5 mL acetic acid was treated with zinc dust (1.58 g, 320 mesh) and the resulting suspension stirred at room temperature for three hours. The reaction mixture was filtered and the filtrate concentrated. The residue was dissolved in ether (30 mL) and extracted with aqueous 1N HCl (3×15 mL). The combined acid extracts are made basic (pH=11) with potassium carbonate and the resulting aqueous solution was extracted with CH 2 Cl 2 (5×15 mL). The combined organic extracts were dried (Na 2 SO 4 , filtered and concentrated. The residue (0.30 g) was converted to its HCl salt by dissolution in ether and treatment with a saturated solution of HCl (gas) in ether. The solid which formed was collected by filtration and dried under vacuum (100° C.) to give the title compound (0.25 g, 54%) as a white solid mp >270° C. Anal (C 16 H 19 N.HCl) Calc'd: C, 72.85; H, 8.40; N, 5.31; Cl, 13.44 Found: C, 72.66; H, 8.38, N, 4.98; Cl, 13.83 EXAMPLE 24 ##STR36## (±)-2,3,4,5-Tetrahydro-8-methoxy-3a,9b-butano-1H-benz[g]indole In a manner similar to that described in Example 23, the product of Example 20 (3.76 g, 8.67 mmol) was converted to the title compound (1.47 g, 70%) as an oil. An analytical sample was prepared by crystallization of the fumarate salt from acetaone which gave a white solid mp 203°-204° C. Anal. (C 17 H 23 NO.C 4 H 4 O 4 ) Calc'd: C, 67.54; H, 7.29; N, 3.75 Found: C, 67.55; H, 7.18; N, 3.61 EXAMPLE 25 ##STR37## (±)-2,3-Dihydro-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole In a manner similar to that described in Example 23, the product of Example 21 is converted to the title compound. EXAMPLE 26 ##STR38## (±)-2,3-Dihydro-7-methoxy-1H,4H-3a,8b-butanoindeno-[1,2-b1pyrrole In a manner similar to that described in Example 23, the product of Example 22 is converted to the title compound. EXAMPLE 27 ##STR39## (±)-2,3,4,5-Tetrahydro-1-methyl-3a,9b-butano-1H-benz[g]indole hydrochloride A solution of the product from Example 18 (0.77 g, 2.56 mmol) in 5 mL of THF was added dropwise to a suspension of lithium aluminum hydride (0.76 g, 20.0 mmol) in 15 mL of THF. The reaction mixture was stirred at room temperature for 18 hours and then heated to reflux for 1 hour. The reaction mixture was cooled to room temperature and quenched by the addition of small portions of Na 2 SO 4 -10H 2 O until no further gas evolution was observed. The reaction mixture was filtered and the filtrate was concentrated. The residue was dissolved in ether and treated with a saturated solution of dry HCl in ether. The solid which formed was collected by suction filtration and dried under vacuum (100° C.) to give the product (0.51 g, 72%) as a white solid mp 241°-253° C. Anal. (C 17 H 23 N.HCl) Calc'd: C, 73.49; H, 8.71; N, 5.04; Cl, 12.76 Found: C, 73.39; H, 8.73; N, 4.82; Cl, 13.16 EXAMPLE 28 ##STR40## (±)-2,3,4,5-Tetrahydro-8-methoxy-1-methyl-3a,9b-butano-1H-benz[g]indole A solution of the product from Example 24 (0.79 g, 3.08 mmol) and sodium cyanoborohydride (0.80 g, 12.7 mmol) in 10 mL methanol was treated dropwise with a 37% aqueous formalin solution (5 mL). The resulting solution was stirred at room temperature for 30 minutes, concentrated, and partitioned between 1N HCl (20 mL) and ether (20 mL). The organic phase was extracted with IN HCl (2×10 mL) and the combined aqueous extracts were washed with ether. The aqueous phase was made basic with K 2 CO 3 and extracted with CH 2 Cl 2 (3×20 mL). The combined organic extracts were dried K 2 CO 3 , filtered and concentrated to give the title compound (0.87 g, quantitative) as a white solid mp 100°-102° C. Anal. (C 18 H 25 NO) Calc'd: C, 79.66; H, 9.29; N, 5.16 Found: C, 79.52; H, 9.53; N, 4.71 EXAMPLE 29 ##STR41## (±)-2,3-Dihydro-1-methyl-1H,4H-3a,8b-butanoindeno-[1,2-b]pyrrole In a manner similar to that described in Example 28, the product of Example 25 is converted to the title compound. EXAMPLE 30 ##STR42## (±)-2,3-Dihydro-7-methoxy-1-methyl-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrole In a manner similar to that described in Example 28, the product of Example 26 is converted to the title compound. EXAMPLE 31 ##STR43## (±)-2,3,4,5-Tetrahydro-1-ethyl-3a,9b-butano-1H-benz[g]indole fumarate In a manner similar to that described in Example 28, the product from Example 23 (0.30 g, 1.32 mmol) and sodium cyanoborohydride (0.30 g, 4.77 mmol) was treated dropwise with acetaldehyde (0.20 g, 4.10 mmol) in 5 mL of methanol. Workup followed by crystallization of the fumarate salt from acetone gave the title compound (0.32 g, 65%) as a white solid mp 172°-173° C. Anal. (C 18 H 25 N.C 4 H 4 O 4 ) Calc'd: C, 71 13; H, 7.87; N, 3.77 Found: C, 70.90: H, 7.79; N, 3.75 EXAMPLE 32 ##STR44## (±)-2,3,4,5-Tetrahydro-8-methoxy-1-ethyl-3a,9b-butano-1H-benz[g]indole hydrobromide In a manner similar to that described in Example 31, the product of Example 24 (0.27 g, 1.13 mmol) and acetaldehyde (0.32 g, 7.12 mmol) are reacted. Workup, followed by crystallization from ether and HBr gave the title compound (0.27 g, 64%) as a white solid mp 248°-251° C. Anal. (C 19 H 27 NO.HBr) Calc'd: C, 62.29; H, 7.71; N, 3.82; Br, 21.81 Found: C, 62.39; H, 7.65; N, 3.77; Br, 21.98 EXAMPLE 33 ##STR45## (±)-2,3,4,5-Tetrahydro-1-propyl-3a,9b-butano-1H-benz[g]indole hydrobromide In a manner similar to that described in Example 32, the product from Example 23 (0.25 g, 1.10 mmol) and propionaldehyde (0.20 g, 3.47 mmol) was converted to the title compound (0.23 g, 60%) as a white solid mp 196`-198° C. Anal. (C 19 H 27 N.HBr) Calc'd: C, 64.92; H, 8.13; N, 4.07; Br, 23.09 Found C, 65.14; H, 8.06; N, 4.00; Br, 22.80 EXAMPLE 34 ##STR46## (±)-2,3,4,5-tetrahydro-1-(cyclopropylmethyl)-3a,9b-butano-1H-benz[g]indole fumarate In a manner similar to that described in Example 31, the product from Example 23 (0.25 g, 1.10 mmol) and cyclopropanecarboxaldehyde (0 23 g, 1.10 mmol) was converted to the title compound (0.26 g, 58%) as a white solid mp 150°-152° C. Anal. (C 20 H 27 N.1.2.C 4 H 4 O 4 ) Calc'd: C, 70.80; H, 7.62; N, 3.33 Found: C, 71.05; H, 7.67, N, 3.32 EXAMPLE 35 ##STR47## (±)-2,3,4,5-tetrahydro-1-phenylmethyl-3a,9b-butano-1H-benz[g]indole hydrochloride In a manner similar to that described in Example 32, the product from Example 23 (0.34 g, 1.50 mmol) and benzaldehyde are reacted. Workup, followed crystallization from ether and HCl gave the title compound (0 22 g, 42%) as a white solid mp 235-237° C. Anal. (C 23 H 27 N.HCl) Calc'd: C, 78.05; H, 7.98; N, 3.96; Cl, 10.02 Found: C, 77.60; H, 8.00, N, 3.34; Cl, 10.24 EXAMPLE 36 ##STR48## (±)-2,3,4,5-Tetrahydro-1-(2-propenyl)-3a,9b-butano-1H-benz[g]indole In a manner similar to that described in Example 32, the product from Example 23 is converted to the title compound. EXAMPLE 37 ##STR49## (±)-2,3,4,5-Tetrahydro-3a,9b-butano-1H-benz[g]indol-8-ol A solution of the product from Example 24 is heated to reflux in 48% aqueous HBr until the starting material is consumed. The reaction mixture is poured into cold NH 4 OH solution and extracted into ethyl acetate. The combined organic extracts are dried (Na 2 SO 4 ) and concentrated to give the title compound. EXAMPLE 38 ##STR50## (±)-2,3,4,5-Tetrahydro-1-methyl-3a,9b-butano-1H-benz[g]indol-8-ol In a manner similar to that described in Example 37, the product from Example 28 is converted to the title compound. EXAMPLE 39 ##STR51## (±)-2,3-Dihydro-1H,4H-3a,8b-butanoindeno[1,2-b]pyrrol-7-ol In a manner similar to that described in Example 37, the product from Example 26 is converted to the title compound. EXAMPLE 40 ##STR52## (±)-2,3-Dihydro-1-methyl-1H,4H-3a,8b-butanoindeno[1,2-b]-pyrrol-7-ol In a manner similar to that described in Example 37, the product from Example 30 is converted to the title compound. EXAMPLE 41 ##STR53## 3',3",4',4"-Tetrahydrodispiro[cyclopentane-1,1'(2'H)-napthlene-2',2"(5"H)-furan]-5"-one A solution of triethylsilyl N,N,N',N'-tetramethyl phosphoramidate (J. Amer. Chem. Soc. 1978, 100, 3468) (1.1 eq.) in anhydrous ether is cooled to 0° C. and treated with acrolein (1.0 eq.) in anhydrous ether. The resulting solution is stirred at 0° C. for 4.5 hours then cooled to -78° C. and a solution of n-butyllithium (1.0 eq.) is added. The resulting solution is treated with the product from Example 1 (1.0 eq.) and stirred at -78° C. for several hours. The reaction mixture is quenched with brine and extracted with several portions of ether. The combined extracts are dried and concentrated. The residue is dissolved in THF and cooled to 0° C. and tetra-n-butylammonium flouride (5 eq.) is added. The reaction mixture is warmed to room temperature and worked up as above to give the title compound. EXAMPLE 42 ##STR54## 3',3",4',4"-Tetrahydro-7, methoxydispiro-[cyclopentane-1,1'(2'H)-napthlene-2',2"(5"H)-furan1-5"-one In a manner similar to that described in Example 41, the product from Example 2 is converted to the title compound. EXAMPLE 43 ##STR55## 3",4"-Dihydrodispiro[cyclopentane-1,1'-[1H]indene-2'(3'H),2"(5"H)-furan]-5"-one In a manner similar to that described in Example 41, the product from Example 3 is converted to the title compound. EXAMPLE 44 ##STR56## 3",4"-Dihydro-6'-methoxydispiro[cyclopentane-1,1'-[1H]indene-2'(3'H),2"(5"H)-furan]-5"-one In a manner similar to that described in Example 41, the product from Example 4 is converted to the title compound. EXAMPLE 45 ##STR57## (±)-3',4'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-naphthalene]-2'-propanamide A solution of the product from Example 41 is placed in a high pressure reactor and dissolved in tetrahydrofuran. Ammonia is condensed into the solution and the reaction vessel is sealed and the reaction mixture is stirred at room temperature for approximately 24 hours. The reaction vessel is vented and the remaining solvent is concentrated to give the title compound. EXAMPLE 46 ##STR58## (±)-3',4'-Dihydro-2'-hydroxy-7'-methoxyspiro-[cyclopentane-1,1'(2'H)-naphthalene]-2'-propanamide In a manner similar to that described in Example 45, the product from Example 42 is converted to the title compound. EXAMPLE 47 ##STR59## (±)-2',3'-Dihydro-2'-hydroxyspiro[cyclopentane-1,1'-[1H1indene]-2'-propanamide In a manner similar to that described in Example 45, the product from Example 43 is converted to the title compound. EXAMPLE 48 ##STR60## (±)-2',3,-Dihydro-2'-hydroxy-6'-methoxyspiro[cyclopentane-1,1'-[1H]indene]-2'-propanamide In a manner similar to that described in Example 45, the product from Example 44 is converted to the title compound. EXAMPLE 49 ##STR61## (±)-2'-(3-Aminopropyl)-3',4'-dihydrospiro[cyclopentane-1,1'(2'H)napthalen]-2'-ol A solution of the product from Example 45, in tetrahydrofuran (THF) is added dropwise to a suspension of lithium aluminumhydride in THF. The resulting suspension is heated to reflux for 1 hour and then stirred at room temperature for 18 hours. The reaction mixture is quenched by the addition of small portions of Na 2 SO 4 -10H 2 O until no more gas evolution is observed. The resulting suspension is filtered and the filtrate is concentrated to give the title compound. EXAMPLE 50 ##STR62## (±)-2'-(3-Aminopropyl)-3',4'-dihydro-7',-methoxyspiro[cyclopentane-1,1'(2'H)napthalen]-2'-ol In a manner similar to that described in Example 49, the product from Example 46 is converted to the title compound. EXAMPLE 51 ##STR63## (±)-2'-(3-Aminopropyl)-2',3'-dihydrospiro-[cyclopentane-1,1'-[1H]inden]-2'-ol In a manner similar to that described in Example 49, the product from Example 47 is converted to the title compound. EXAMPLE 52 ##STR64## (±)-2'-(3-Aminopropyl)-2',3'-dihydro-6'-methoxyspiro[cyclopentane-1,1'(2',H)-NAPTHLENE]-2'-yl)propyl]carbamate In a manner similar to that described in Example 49, the product from Example 48 is converted to the title compound. EXAMPLE 53 ##STR65## 2,2,2-Trichloroethyl (±)-[3-(3',4'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'(2'H)-napthlene]-2'-yl)propyl[carbamate A solution of the product from Example 49 (1.0 eq.) and triethylamine (1.1 eq.) in CH 2 Cl 2 is cooled to 0° C. and a solution of 2,2,2-trichloroethylchloroformate (1.1 eq.) in CH 2 Cl 2 is added dropwise. The resulting solution is stirred at 0° C. for 30 minutes and warmed to room temperature. The reaction mixture is washed with bicarbonate, dried and concentrated t give the title compound. EXAMPLE 54 ##STR66## 2,2,2-Trichloroethyl (±)-[3-(3',4'-dihydro-2'-hydroxy-7'-methoxyspiro[cyclopentane-1,1'(2'H)napthlene]-2'-yl)propyl]carbamate In a manner similar to that described in Example 53, the product from Example 50 is converted to the title compound. EXAMPLE 55 ##STR67## 2,2,2-Trichloroethyl (±)-[3-(2',3'-dihydro-2'-hydroxyspiro[cyclopentane-1,1'[1H]inden]-2'yl)propyl]carbamate In a manner similar to that described in Example 53, the product from Example 51 is converted to the title compound. EXAMPLE 56 ##STR68## 2,2,2-Trichloroethyl (±)-[3-(2',3'-dihydro-2'-hydroxy-6'-methoxyspiro[cyclopentane-1,1'[1H]inden]-2'-yl)propyl]carbamate In a manner similar to that described in Example 53, the product from Example 52 is converted to the title compound. EXAMPLE 57 ##STR69## 2,2,2-Trichloroethyl (±)-3,4,5,6-tetrahydro-4a,10b-butanobenz[h]quinoline-1(2H)-carboxylate In a manner similar to that described in Example 18, the product from Example 53 is converted to the title compound. EXAMPLE 58 ##STR70## 2,2,2-Trichloroethyl (±)-3,4,5,6-tetrahydro-9-4a,10b-butanobenz[h]quinoline-1(2H)-carboxylate In a manner similar to that described in Example 18, the product from Example 54 is converted to the title compound. EXAMPLE 59 ##STR71## 2,2,2-Trichloroethyl (±)-3,4-dihydro-4a,9b-butano-5H-indeno[1,2-b]pyridine-1(2H)-carboxylate In a manner similar to that described in Example 18, the product from Example 55 is converted to the title compound. EXAMPLE 60 ##STR72## 2,2,2-Trichloroethyl (±)-3,4-dihydro-8-methoxy-4a,9b-butano-5H-indeno[1,2-b]pyridine-1(2H)-carboxylate In a manner similar to that described in Example 18, the product from Example 56 is converted to the title compound. EXAMPLE 61 ##STR73## (±)-1,2,3,4,5,6-Hexahydro-4a,10b-butanobenz[h]-quinoline In a manner similar to that described in Example 23, the product from Example 57 is converted to the title compound. EXAMPLE 62 ##STR74## (±)-1,2,3,4,5,6-Hexahydro-9-methoxy-4a,10b- butanobenz[h]-quinoline In a manner similar to that described in Example 23, the product from Example 58 is converted to the title compound. EXAMPLE 63 ##STR75## (±)-1,2,3,4-Tetrahydro-4a,9b-butano-5H-indeno[1,2-b]pyridine In a manner similar to that described in Example 23, the product from Example 59 is converted to the title compound. EXAMPLE 64 ##STR76## (±)-1,2,3,4-Tetrahydro-8-methoxy-4a,9b-butano-5H-indeno[1,2-b]pyridine In a manner similar to that described in Example 23, the product from Example 60 is converted to the title compound. EXAMPLE 65 ##STR77## (±)-1,2,3,4,5,6-Hexahydro-1-methyl-4a,10b-butanobenz[h]quinoline In a manner similar to that described in Example 28, the product from Example 61 is converted to the title compound. EXAMPLE 66 ##STR78## (±)-1,2,3,4,5,6-Hexahydro-9-methoxy-1-methyl-4a,10b-butanobenz[h]quinoline In a manner similar to that described in Example 28, the product from Example 62 is converted to the title compound. EXAMPLE 67 ##STR79## (±)-1,2,3,4-Tetrahydro-1-methyl-4a,9b-butano-5H-indeno[1,2-b]pyridine In a manner similar to that described in Example 28, the product from Example 63 is converted to the title compound. EXAMPLE 68 ##STR80## (±)-1,2,3,4-Tetrahydro-8-methoxy-1-methyl-4a,9b-butano-5H-indeno[1,2-b]pyridine In a manner similar to that described in Example 28, the product from Example 64 is converted to the title compound. EXAMPLE 69 ##STR81## (±)-1,2,3,4,5,6-Hexahydro-4a,10b-butanobenz[h]quinoline-9-ol In a manner similar to that described in Example 37, the product from Example 62 is converted to the title compound. EXAMPLE 70 ##STR82## (±)-1,2,3,4,5,6-Hexahydro-1-methyl-4a,10b-butanobenz[h]quinoline-9-ol In a manner similar to that described in Example 37, the product from Example 64 is converted to the title compound. EXAMPLE 71 ##STR83## (±)-1,2,3,4-Tetrahydro-4a,9b-butano-5H-indeno[1,2-b]pyridin-8-ol In a manner similar to that described in Example 37, the product from Example 66 is converted to the title compound. EXAMPLE 72 ##STR84## (±)-1,2,3,4-Tetrahydro-1-methyl-4a,9b-butano-5H-indeno[1,2-b]pyridin-8-ol In a manner similar to that described in Example 37, the product from Example 68 is converted to the title compound.

A novel series of tetracyclic amines, methods of preparation, compositions containing the amines, and methods for using them in the treatment and/or prevention of cerebrovascular disorders are disclosed.

FIELD [0001] The present invention relates generally to communications devices, and more particularly to mobile hand held communications networks. BACKGROUND [0002] Many people are familiar with mobile handsets. Mobile handsets are typically small electronic devices that communicate with a base station to place mobile calls. Many mobile handsets also perform other features in addition to placing mobile calls. For example, some mobile handsets are capable of transmitting data in addition to voice. [0003] A popular feature on many mobile handsets is push-to-talk. With push-to-talk a mobile handset user is able to push a single button to complete a call to a specific mobile handset, or some small number of mobile handsets. The mobile handset acts like a “walkie-talkie.” However, generally, instead of communicating directly to another “walkie-talkie” a mobile handset with push-to-talk typically communicates through a base station to another mobile handset using a single button push to initiate the connection. Additionally, like a “walkie-talkie” when using a mobile handset with push-to-talk, after a user pushes the button they are able to speak without having to wait for the other mobile handset to ring and the other user to answer. [0004] However, some delay between pushing the button and connecting to the other mobile handset may exist. It would be advantageous to try to lower that delay as much as possible. Additionally, while this delay may typically be more noticeable to a user using push-to-talk, or other single button push services, the delay may exist with other mobile handset services including, but not limited to mobile telephone calls and mobile data calls. It would also be advantageous to try to lower the delay as much as possible when using any other communications services that exhibit a delay when communicating with a base station or other transceiver. [0005] One cause of delay when beginning a mobile call, including push-to-talk, and data calls is related to how often a mobile communicates with a base station. Many current mobile handsets are designed to communicate with a base station at specific time intervals. These time intervals are the only time that the mobile handset can begin a mobile call. The longer the delay between intervals, the longer it is likely to take to set up a mobile call. It will be understood by those of skill in the art that the delay will be variable and somewhat random. Depending on when a user initiates a call relative to the next slot cycle. Slot cycle is the time when the mobile handset communicates with the base station. If the user attempts a call close to the next slot cycle, the delay may be relatively short, however, if the user attempts a call just after a slot cycle, the delay may be relatively long. [0006] As stated above one aspect to consider regarding mobile handsets is how often and when the mobile handset should communicate with the base station. Typically, the more often the mobile handset communicates with the base station the faster the mobile handset will be able to respond when the person using the mobile handset attempts to make a call. For example, if the mobile handset communicates with the base station every second, when a user attempts to make a call it will only be one second, at most before the mobile handset is able to communicate with the base station and start the process of placing the call. However, if the mobile handset only communicates with the base station every two seconds, then it could be as long as two seconds before the process of placing the call begins. [0007] So, to speed up placing a mobile call, the mobile handset should communicate with the base station as often as possible. However, communicating with the base station as often as possible has many drawbacks. Transmitting to the base station typically takes power. On a battery-operated device, this can be a critical consideration. Additionally, in many cases the more often a mobile handset communicates with a base station, the fewer mobile handsets that are able to use the base station. This is due to the fact that the base station typically has a limited number of transceivers to communicate with mobile stations. For this reason, each mobile station is given a time when it can communicate with the base station. Multiple mobile handsets are able to communicate with the base station by time-sharing. The more often a mobile handset communicates with the base station, the fewer other mobile handsets can communicate with the base station. For these reasons, and possibly others, the delay between communications between mobile handsets and base stations is not typically made arbitrarily short. [0008] Referring to FIG. 12 more details of communication between mobile handsets and base stations will be discussed. The diagram 700 includes a graph 704 . The graph 704 shows when a mobile handset 724 communicates with a base station 722 . The communication is shown as electromagnetic signals 720 . Communications occur at 707 , 709 , and 712 . It should be noted that this is only one possible example. The time between communications between base station and mobile handset may not always the same. [0009] Typically the slot cycle index is initially negotiated between the base station and the mobile handset. by the manufacturer. The number of clock cycles is known as slot cycle index. Slot cycle index is not a linear. Slot cycle index 0 indicates that communication occurs every cycle. Slot cycle index 1 indicates that a communication occurs every cycle. Referring back to FIG. 12 a slot cycle index 3 indicates that a communication occurs every four cycle. Slot cycle index above slot cycle index 3 are also possible. Slot cycle index timing can be summarized as follows, where x is the slot cycle index: TIME BETWEEN COMMUNICATION=1.28×(2 n ) For example, for slot cycle index 0 a communication occurs every 1.28 seconds, slot cycle index 1 is a communication every 2.56 seconds, and for slot cycle 2 a communication occurs every 5.12 seconds. Other slot cycle indexes are possible. Additionally, “negative” slot cycles are possible. In one possible implementation of “negative” slot cycles the number “n” in the equation above is a negative number. The use of “negative” slot cycles allows communication to occur more often than every 1.28 seconds. BRIEF DESCRIPTION OF THE FIGURES [0010] FIG. 1 illustrates a flowchart describing one method of dynamically changing a slot cycle index, according to one embodiment of the present invention. [0011] FIG. 2 illustrates a mobile handset user, in an embodiment of the present invention. [0012] FIG. 3 illustrates a flowchart describing one method of dynamically changing a slot cycle index based on a trigger event, according to one embodiment of the present invention. [0013] FIG. 4 illustrates a flowchart describing one method of dynamically changing a slot cycle index based on a trigger event, according to one embodiment of the present invention. [0014] FIG. 5 illustrates a flowchart describing one method of dynamically changing a slot cycle index based on a trigger event, according to one embodiment of the present invention. [0015] FIG. 6 illustrates one embodiment of a handset. [0016] FIG. 7 illustrates a base station, in an embodiment of the present invention. [0017] FIG. 8 illustrates a base station, a mobile phone, and a method of use, in an embodiment of the present invention. [0018] FIG. 9 illustrates a graph of a clock signal for reference timing, in an embodiment of the present invention. [0019] FIG. 10 illustrates a system and method for dynamically changing a slot cycle index, according to one embodiment of the present invention. [0020] FIG. 11 illustrates a graph showing several possible slot cycle priorities, in an embodiment of the present invention. [0021] FIG. 12 generally illustrates prior art involving communication between mobile handsets and a base station including a slot cycle graph. SUMMARY [0022] Many people use mobile handsets. As many users may have noticed, sometimes it can take a while to complete a mobile call. One thing that may affect is known as slot cycle index. The slot cycle index is the amount of time that the mobile handset must wait before communicating with the base station. The higher the slot cycle index the longer the mobile handset must wait before communicating with the base station. The lower the slot cycle index the shorter the delay. However shorter slot cycle priorities limit the number of mobile handsets that can communicate with a base station. Additionally, shorter slot cycle index typically increase the amount of battery power used by the mobile handset, commonly lowering standby and talk time. [0023] The slot cycle index is currently negotiated by a mobile handset and a base station. However, if the slot cycle index could be selected dynamically a mobile handset that operates more efficiently for the user would result. Talk time could be maximized when the battery, or other mobile power source is low, while connect time for a mobile call could be minimized when the battery is near fully charged or at times when the user is likely to make a mobile call. Additionally, location could be used to determine the likelihood that the user will make a mobile call. However, current network usage would typically need to be considered when determining if the slot cycle index should be changed. Mobile handset users could also charged for quicker response times, or mobile handset users on more expensive plans could be given typically faster response times. Many different things can be considered in determining when to adjust slot cycle index. More examples will be given below. [0024] Dynamically adjusting slot cycle index allows a mobile handset to, in some cases, operate more efficiently. In some cases the mobile handset may exhibit faster response time due to lower slot cycle index, while in other cases the mobile handset may use less battery power due to the higher slot cycle index. In addition, the service provider will be able to dynamically change slot cycle index to allow more users access to a base station. DETAILED DESCRIPTION [0025] Several methods of dynamically changing slot cycle index are possible. Referring now to FIG. 1 a flowchart 100 that illustrates one possible example will be discussed. [0026] The flowchart 100 shows one example of a method of dynamically changing slot cycle index. The flowchart 100 begins at 103 . In step 106 a request from a mobile handset to operate at a higher slot cycle index is received. The mobile handset may send a request to operate in a higher slot cycle index for several reasons. Typically, the occurrence of a trigger event will cause the mobile handset to send the request. Trigger events at the mobile handset can include the battery power available at the mobile handset, the time of day, or feature availability at the mobile handset. More details regarding trigger events will be discussed with respect to FIG. 3 . Additionally, trigger events that are generally related to specific devices, such as the mobile handset or the base station, as well as groups of devices such, as the network will be discussed with respect to FIG. 10 . [0027] It is determined if the current system loading will allow an increase in slot cycle index for the mobile handset in step 109 . If the current system loading will allow, the mobile handset is set at a higher slot cycle index in step 113 . As can be seen in this example, typically, the base station and the mobile station negotiate to determine if the mobile handset should operate in a higher slot cycle index. [0028] The flowchart 100 is one possible example of a method of dynamically changing slot cycle index. Other examples are possible. For example, a request may come from a base station instead of a mobile handset. In this example, the base station sends a request to the mobile handset to operate at a higher slot cycle index. For this example, as discussed with respect to FIG. 1 above, typically, the base station and the mobile handset negotiate to determine if the mobile handset slot cycle index should be changed. Additionally, slot cycle index may be increased, as shown, decreased, or kept the same based on different trigger events. [0029] Several examples of trigger events will be discussed below with respect to FIG. 3 below. FIG. 3 includes discussions of trigger events that may increase or decrease slot cycle index. In some cases different trigger events may be considered at the same time to determine if slot cycle index should be changed. The term trigger event is used throughout to describe an event that causes the method to change slot cycle index. However, in some cases the term trigger state may be better. For example, if several factors are considered at one time, it is the state of each factor that determines the outcome. Additionally, it may be the change of a single factor that causes the determination to occur. Alternately, several states changing could cause a determination to occur. In this application, the term trigger event will be used to describe a state, or change in state that causes a request to operate at a different slot cycle index to be transmitted. In FIG. 2 an example of a specific mobile handset user will be discussed. [0030] Some advantages include the ability to conserve battery power when the battery is low by raising slot cycle index. However, in some cases it may be determined that slot cycle index should be increased even though the battery is low. Additionally, system loading can typically, in some cases, be lowered if necessary during times users are using up network capacity. [0031] Referring now to FIG. 2 an example will be discussed with respect to a diagram 125 . The diagram 125 includes a sports stadium 127 , an office building 130 , and a road 131 . Additionally, the diagram 125 includes a car 133 and a house 135 . In the example of FIG. 2 a mobile handset user, Mary, begins her day at the house 135 . When at home, Mary does not tend to user her mobile handset. However, during her drive to work Mary tends to make many calls using her mobile handset. Mary's mobile handset requests a higher slot cycle index during times of day that the mobile handset is typically used. [0032] Typically, on her way to work Mary's mobile handset is set at a higher slot cycle index. When Mary arrives at work in her building 130 she continues to use her mobile handset throughout the day. The mobile handset typically operates in a higher slot cycle index. This enables Mary to complete calls more quickly typically. However, Mary's building is close to the sports stadium 127 . On days that sports events occur at the stadium 127 many people normally attend, and typically carry mobile handsets. The large number of people at the stadium 127 put a large load on the base station 140 that is near the stadium 127 . When the loading at the base station 140 is high, Mary's mobile handset is not allowed to operate at a higher slot cycle index. The base station 140 is able to communicate with more mobile handsets when the slot cycle index is decreased. [0033] It should be pointed out that the discussion of FIG. 2 is only one possible example. Dynamically modifying slot cycle index could occur for a variety of reasons. Additionally, not allowing slot cycle index to be changed could happen for a variety of reasons. Slot cycle index can be increased when a trigger event occurs, as will be discussed with respect to FIG. 3 or slot cycle index can be decreased when a trigger event occurs as discussed with respect to FIG. 4 . [0034] Referring now to FIG. 3 , a flowchart 200 will be discussed. The flowchart 200 begins at step 202 . At step 204 it is determined that a trigger event has occurred. The trigger event is evaluated in step 206 and a determination is made to request a higher priority slot cycle in step 209 . The request for a higher priority slot cycle is made in step 212 . In the flowchart 200 of FIG. 3 a trigger event occurs that causes a request for a higher slot cycle index. However, a trigger event can also occur that would cause a request for a lower slot cycle index, as will be discussed with respect to FIG. 4 . Many events can be considered trigger events. Several examples will be discussed below, however, other examples are possible. One example of a trigger event is battery power. Operating a mobile handset in a high slot cycle index state usually increases the amount of battery power consumed for a given period of time. High battery power may be a trigger event to operate in a higher slot cycle index. Conversely, low battery power may be a trigger event to operate in a lower slot cycle index. [0035] Another example of a trigger event is time of day. If the current time of day is one that a mobile handset user tends to make many calls, or one that the service providers expect many calls to be made, a request to operate in a higher slot cycle index may occur. Again, as with the battery power example, the converse is also true. If it is a time of day when it is unlikely that a call will occur, this may be a trigger event to operate in a lower slot cycle index. [0036] A third example of possible trigger events is system loading. Higher slot cycle index places increased demands on system resources. When system loading is low, slot cycle index may typically be increased without placing a burden on the base station that the based station is unable to meet. However, when system loading is high, one possible way to decrease these demands is to lower the slot cycle index on some mobile handsets. It is important to note that these are only examples. [0037] The examples discussed above and other examples discussed below will be factors considered when deciding to increase or decrease slot cycle index. In some cases several different trigger events will be considered before an increase or a decrease of slot cycle index is made. For example, if battery power is low, the time of day is one that a call is likely to occur, and the system loading would allow for an increase slot cycle index, the slot cycle index may be decreased to save battery power, even though two other factors would allow for an increase in slot cycle index. [0038] Another trigger event is location. The mobile handset may be in a location where the user has made one or more, possibly many, mobile calls in the past. In this case it may be advantageous to increase the slot cycle index of the mobile handset. However, typically, other trigger events will be considered. For example, as discussed with respect to FIG. 2 when Mary is at work but a sporting event is occurring near by, even though she usually makes many calls using her mobile handset, it may not be possible to increase the slot cycle index of her mobile handset because system loading is to large. [0039] Location may effect the decision to increase or decrease slot cycle index in another way. Location tends to effect the amount of transmit power needed to communicate with a base station. In locations where transmit power is high it may be advantageous to decrease slot cycle index. In locations where transmit power is low, it may be advantageous to increase slot cycle index. As with examples discussed above, transmit power can be considered in conjunction with other factors. [0040] In another example, battery power may be high, while system loading is low and time of day is one that a call is likely to occur, however, the mobile handset may be located at a location where a large amount of transmit power is needed to communicate with the base station. In that case it may be advantageous to operate in a lower slot cycle index. [0041] In some cases mobile handset users may pay for higher performance service. For example, users may be more to have higher slot cycle index. In some cases, higher slot cycle index may be included on higher priced plans as part of a package of services provided. [0042] In some cases it may be likely that when a call occurs another call may occur soon after. The fact that a call has recently occurred may be used as a trigger event to increase slot cycle index. One case where several calls in rapid succession tend to be likely is one button push services, such as push-to-talk. [0043] Additionally, in some cases a feature may exist that requires higher slot cycle index. Or, in some cases the carrier or the mobile handset may desires higher slot cycle performance. Feature availability may be a trigger event. When a feature is available, for example, due to mobile handset proximity to a base station that supports the feature, the availability of the feature may trigger an increase, or decrease in slot cycle index, depending on the requirements of the feature. As with other trigger events, several trigger events can be combined to determine if slot cycle index should be increased or decreased. [0044] As was discussed above, with respect to FIG. 3 , a trigger event may trigger an increase in slot cycle index, while another trigger event may cause a decrease in slot cycle index. As shown in FIG. 4 , a trigger event may cause a request for a lower slot cycle. FIG. 4 is a flowchart 225 . The flowchart 225 begins at step 227 . At step 229 it is determined that a trigger event has occurred. In step 232 the trigger event is evaluated and it is determined that triggers a lower slot cycle has occurred. In step 234 it is determined that a request for a lower slot cycle should occur. A lower priority slot cycle is requested at step 240 . Summarizing FIGS. 3 and 4 , a trigger event occurs and depending on the type of trigger event a request for a lower or higher slot cycle occurs. In some cases a combination of trigger events or current states may be considered when deciding to request a higher or lower slot cycle. Additionally, trigger events or states may occur in a mobile handset, at a base station, or they may be inherent in the service that a user has purchased. For examples, see FIG. 10 below. The combination of trigger events discussed above could occur in a combination of the mobile handset, and base station and could also be based on the service purchase. Advantages may include the ability to increase performance of a mobile handset during periods of time or in locations where a mobile handset user is likely to make a mobile call. [0045] It will be clear to those of skill in the art that the converse is also true. The lack of some trigger events may cause slot cycle index to be increased. [0046] Referring now to FIG. 5 , a flowchart 250 will be discussed. The flowchart 250 is similar to the flowchart 200 of FIG. 3 . The flowchart 250 includes the addition of several possible trigger events, listed at step 255 . Beginning at 252 , the flowchart 250 determines that a trigger event has occurred at step 255 . Step 255 is the same or similar to step 205 of FIG. 3 . Possible trigger events include, but are not limited to: available battery power, time of day, location, transmit power needed, system loading, priority, occurrence of a call, and feature availability. As stated above, several trigger events can be considered when determining if slot cycle index should be increased, decreased, or kept the same. Additionally, each trigger event may be given a different weight when determining slot cycle index. At step 260 a request for a slot cycle index change occurs. Step 260 of FIG. 5 is the same or similar to a combination of 212 of FIG. 3 and step 240 of FIG. 4 . [0047] Referring back to step 255 , low battery power would typically be considered a trigger event for a lower priority slot cycle because higher priority slot cycles typically consume more battery power. The converse is also true. A high battery power would typically be considered a trigger event for a higher priority slot cycle. It should be noted that this is only one example. It will be understood by those of skill in the art that “low” battery power and “high” battery power are not precisely defined here and may vary widely from one specific implementation to another. [0048] Power stored in a battery can be thought of as a predetermined percentage, for example, 100% or fully charged, 75% charged, 50%, 25% charged, etc. Generally the percentage charge of a battery can be a function of the battery voltage, which can decrease as the battery discharges. Thus the charged state of a battery in a battery powered mobile handset can be a trigger event. For example, if enough charge is stored in the battery to complete at least one call, this can be a trigger event to request a different slot cycle index. The percentage charge can also be a trigger event, for example, greater than 25%, 50%, or 75%. In an embodiment that uses a mobile power source other than a battery, reaching a predetermined level of mobile power can be a trigger event. [0049] In some cases battery power may be considered with other trigger events. Additionally, in some examples, battery power may not be considered at all. Specific trigger events used in any particular application can be customized depending on the needs of that particular application. Some trigger events will be discussed further with respect to FIG. 10 . Advantages may include the ability to change slot cycle index to conserve battery power when battery power is low. [0050] When placing a call, especially a push to talk call, it may be likely that several calls will be placed in rapid succession. Generally increasing slot cycle index when a call has recently been placed will tend to have the advantage of increasing the ability of the mobile handset to place calls rapidly. For example, slot cycle index can be increased when a call has been placed within ten minutes, thirty minutes, or some other period of time. [0051] Referring now to FIG. 6 , a mobile handset 280 will be discussed. The mobile handset 280 includes an antenna 284 . The antenna 284 is a transducer for coupling radio frequency signals to a transceiver 282 . The transceiver 282 includes a transmitter and a receiver for sending and receiving radio frequency signals. The transceiver 282 is coupled to a processor 295 . The processor 295 is used to perform processing function necessary for the mobile handset. It will be understood by those of skill in the art that the processor could be a single processor or multiple processors. Additionally, the processor could be a microprocessor, a microcontroller, or multiple microprocessors or microcontrollers, or similar devices. The processor could be a digital signal processor or multiple digital signal processors. The processor could be a combination of different types of processors, including, but not limited to microprocessors, microcontrollers, and digital signal processors. The processor could also be stand alone digital logic, programmable logic, such as field programmable gate arrays, complex programmable logic devices, or other forms of programmable logic. The processor could be any circuit capable of performing the steps included in the claims. The processor 295 is coupled to a memory 293 . The memory 293 is used to store information used by the processor 293 . [0052] A mobile power source in the form of a battery, 298 is coupled to the processor to provide power to the processor. It will be clear to those of skill in the art that the battery 298 may provide power to other circuits in the mobile handset. Additionally, the battery 298 may be other types of mobile power sources, for example, the battery 298 may actually be a fuel cell, or other mobile power source. Additionally, the mobile handset is enclosed by a case 288 . In many cases lowering the slot cycle index will tend to conserve battery power at the mobile handset. Advantages may also include the ability to increase a mobile handsets performance when placing a push-to-talk call. In some cases the push-to-talk call may connect more quickly. [0053] Referring now to FIG. 7 , a base station 330 will be discussed. The base station 330 includes an antenna 332 . The antenna couples radio frequency signals to a transceiver 337 . The transceiver 337 is coupled to a processor 349 . Additionally, the processor 349 typically communicates with a terrestrial communications network. The processor 339 is coupled to a memory. The base station 330 is enclosed by a case 334 . Allowing the base station to dynamically change the slot cycle index used by a mobile station will tend to have the advantage of allowing the base station to manage system loading. When system loading is high, slot cycle index may be decreased. Decreased slot cycle index decreases how often mobile handsets communicate with the base station. [0054] Referring now to FIG. 8 a diagram 375 will be discussed. The diagram 375 includes a mobile handset 280 . The mobile handset 280 is the same or similar to the mobile handset 280 of FIG. 6 . Additionally, the diagram 375 of FIG. 8 includes a base station 330 . The base station 330 is the same or similar to the base station 330 of FIG. 6 . The mobile handset 280 and the base station 330 transmit electromagnetic signals to allow information to be communicated between the two devices. It will be clear to those of skill in the art that the base station may communicate with multiple mobile handsets, including the mobile handset 280 . In some cases not all mobile handsets will have dynamically adjustable slot cycle index. In other cases, it is possible that all mobile handsets will have adjustable slot cycle index. Additionally, it is important to note that typically the base station 330 and the mobile handset 280 will negotiate to determine slot cycle index setting. Many different ways to negotiate slot cycle index setting will be apparent to those of skill in the art. For example, the multiple trigger events, as discussed above, can be combined. Different trigger events can have different “weights” associated with them when trying determine what course of action to take. [0055] Additionally, in some cases it may be advantageous to have some trigger events cause slot cycle index to change independent of any other trigger event. For example, when the battery is low, it may be advantageous to always lower slot cycle index regardless of the other trigger events. Similarly, when system loading is high, it may be advantageous to always lower slot cycle index. However, it is important to note that these are only possible examples. In other cases these examples may not apply. In some cases slot cycle index may be increased or kept the same when the battery is low or system loading is high. [0056] In another example, in some cases it may be advantageous to allow one device to dictate slot cycle index to another. For example, perhaps it would be advantageous to not allow a mobile handset to refuse a request to lower slot cycle index. In this example, assume that system loading is high. A base station that is communicating with a mobile station sends a request, or in this case, perhaps it can be considered a command, to operate in a lower slot cycle index. In this example, the mobile handset is required to operate in the lower slot cycle index. It again should be stressed that these are only examples. Other examples are possible. It will be clear to those of skill in the art that specific trigger events, specific “weightings” for trigger events, specific combinations of trigger events, and specific ways to negotiate dynamic slot cycle index can be determined based on the needs of a particular implementation. Many different possibilities will be clear to those of skill in the art. For brevity, only a few examples are shown here. Advantages may include the ability to lower power used to transmit between the mobile handset 280 and the base station 330 . This may be especially important when the battery on the mobile handset 280 is low. [0057] Referring now to FIG. 9 , a diagram 400 will be discussed. The diagram 400 includes a graph of a clock signal 402 . The clock signal 402 is a reference for timing of transmissions between a base station 330 and a mobile handset 280 . For example, the base station 330 and the mobile handset 280 of FIG. 8 . A graph 404 of a dynamic slot cycle is also shown on the diagram 400 . The graph includes a period of time when the handset 280 operates in slot cycle 1406 . After a trigger event 412 the mobile handset 280 operates in slot cycle 0 for a period of time. Another trigger event occurs at 419 . The trigger event 419 is a trigger event that causes a decrease in slot cycle index. After 419 the mobile handset returns to slot cycle 1 . FIG. 9 is only one possible example, other examples are possible. Changes in slot cycle can occur other than just changing from slot cycle 0 to slot cycle 1 . For example mobile handset could change from slot cycle 2 to slot cycle 4 . Slot cycle could be changed by multiple slot cycles in a single change, for example, as stated above, from slot cycle 2 to slot cycle 4 . [0058] As stated above changes in slot cycle could be based a combination of trigger events. For example, the trigger events could be combined in the form of a function. Additionally, the combination of trigger events could be weighted differently. Some trigger events could be considered more important than others. The trigger events could be combined in the form of a function. For example, slot cycle change could be a function of battery power available, system loading, and location. [0059] In one example battery power could be considered more important than the other two trigger events. In this example battery power could be given more weight in a function the determines if a trigger event should occur. [0060] Additionally, these trigger events could be continuously monitored. In another example the trigger events can be monitored continually. In yet another example, the trigger events could be monitored only when one or more trigger events change. It will be clear to those of skill in the art that this is only an example, other examples, using other trigger events, or other combinations of trigger events are possible. Advantages include the ability to change slot cycle based on the conditions during a specific time period. [0061] Referring now to FIG. 10 a diagram 475 is shown. The diagram 475 generally shows the relationship between a network 480 , a base station 482 , a mobile handset 485 , and services 489 . On the diagram under base station 482 location, system load, and feature availability are listed. These trigger events are typically associated with the base station 482 , however, other groupings are possible. For example, feature availability is listed under both base station 482 and handset 485 . Additionally, if the handset could determine system loading, then system loading could be listed under handset 485 . However, handsets do not typically have access to system loading information, so system loading information, so system loading has not been included under handset 485 . The diagram is meant to be general and to show typical groups of trigger events and what devices tend to monitor for those trigger events. But, as can be seen above, the lists are not exhaustive. [0062] The section for handset 485 includes a list of trigger events such as power, time of day, and feature availability. As stated above, the list is intended to be an example. The list is not intended to be exhaustive. Other trigger events are possible. Additionally, trigger events could occur related to headings such as base station 482 , handset 485 , and service 489 in ways not shown on FIG. 10 . For example, if a base station 482 is able to determine battery power available then power could be listed under base station 482 above. However, since typically, the base station 482 does not know the battery power available to a mobile handset 485 , power is not listed under base station 482 . [0063] As stated above, FIG. 10 also includes service 489 . Service 489 includes priority service. In some cases a customer may pay extra for faster call completion typically brought about by higher slot cycle index. In other cases the service may be a part of other prepackaged services. Advantages may include the increased revenue due to the ability to charge some customers for typically faster call completion. However, in some cases, the service may be included with specific calling plans. [0064] Referring now to FIG. 11 a diagram 550 is shown. The diagram 550 is similar to the diagram 400 of FIG. 9 . However, the diagram 550 shows several possible slot cycle priorities 559 , 562 , 568 , 571 and indicates that a mobile handset can switch between the different priorities. Using the diagram 550 , the different slot cycle priorities 559 , 562 , 568 , 571 can easily be compared. It can be seen from the diagram 550 that the higher the slot cycle index, the more often the mobile station communicates with the base station. It should be noted that higher slot cycle index is indicated by a lower slot cycle number. For example' slot cycle 0 is a higher slot cycle index than slot cycle 1 . The ability to dynamically change between slot cycle priorities has many advantages, as discussed above. Dynamically changing slot cycle index typically allows a mobile handset to operate more efficiently and in some cases adapt to the current state of the handset, the network, or the service purchased. [0065] Many examples are discussed above. However, these are only examples. Other examples are possible. Additionally, many advantages are discussed above. However, these are only possible advantages. Advantages may vary from one specific implementation to the next. Additionally, some advantages may be an important aspect of one implementation while unimportant or possibly not included in another. Embodiments should only be limited by the claims.

The slot cycle index is currently negotiated by a mobile handset and a base station. However, if the slot cycle index could be selected dynamically a mobile handset that operates more efficiently for the user would result. Talk time could be maximized when the battery, or other mobile power source is low, while connect time for a mobile call could be minimized when the battery is near fully charged or at times when the user is likely to make a mobile call. Additionally, location could be used to determine the likelihood that the user will make a mobile call. However, current network usage would typically need to be considered when determining if the slot cycle index should be changed. Mobile handset users could also charged for quicker response times, or mobile handset users on more expensive plans could be given typically faster response times. Many different things can be considered in determining when to adjust slot cycle index, such as, for example, battery power, time of day, or system loading. Additionally, combinations of factors can be considered to determine when to adjust slot cycle index.

[0001] The present application is a continuation of U.S. patent application Ser. No. 10/715,218 filed Nov. 17, 2003, now U.S. Pat. No. 7,062,475, which is a continuation of U.S. patent application Ser. No. 09/584,057 filed May 30, 2000, which is abandoned. FIELD OF THE INVENTION [0002] The present invention relates to the field of personal and personalized information services, and more particularly to the field of improved personalized computer user interfaces for database systems, more particularly those systems designed to organize information and information object references. BACKGROUND OF THE INVENTION [0003] Vendors of information appliances, such as personal computers, and even embedded devices with human computer interfaces, have often wrestled with providing an optimal presentation of customized of personalized information, both in the nature of the information to be presented, and the optimal presentation thereof. Personalization and customization of computer user interfaces is often in conflict with a desire for standardization and consistency. Thus, the more an interface is malleable to represent personalized factors, the less that interface represents a standard, and that deviation can lead to support and training difficulties. See, e.g., Horvitz et al, U.S. Pat. No. 6,021,403, expressly incorporated herein by reference. [0004] In order to customize computer user interfaces, typically the visual factors are treated as objects, such as view type, font, color scheme, wallpaper, sounds, icons, and the like, which may be altered globally or locally by altering a characteristic of the visual object. In order to personalize computer user interfaces, typically the layout of different types of information, such as news, weather, financial data and the like, is predicated by interests of the user. [0005] As a separate scheme, computer user interfaces may also track a user's activity, thereby creating a history. It is often desirable to facilitate common functions of programmable interfaces for the user and/or to recall recently performed operations that are desirable to be repeated or for which traceability is desired. Thus, many software constructs record a list of recently used files, which is then presented as a readily accessible list of potential choices for the user. Likewise, graphic user interfaces for operating systems and favorite lists for browsers are generally directly modifiable by the user to alter the selection and grouping of information-related objects presented. [0006] In a system having a hypermedia structure, information objects can be browsed by following links provided between each other. In conventional hypermedia systems, however, a problem may often occur in which a path that the user has followed is lost and the user cannot return to a desired location or the user becomes unable to make out his whereabouts in the system. This problem is generally known as the problem of lost path in the hypermedia system. [0007] Conventional hypermedia systems often have history files that tell the routes the user has followed. Generally, most of such history files simply list character information in the order in which the user has been browsing. Some of the history files indicate the hypermedia links in a tree structure to allow grasping of the connection state of the information objects, while others show the nodes in images reduced in size and sometimes referred to as thumbnails. [0008] Modern Internet browsers, such as Microsoft's Internet Explorer, and Netscape's Navigator provide access to a list of viewed Web pages, albeit through different means. This history is generated automatically based on actual Web pages viewed, and is non-editable by definition, except that Microsoft allows deletion of pages from the history list. Revisits to a Web page add additional versions of the page in the history list of Microsoft Internet Explorer. The browser history is acquired as a list of the Web page addresses referred to as URLs, or uniform resource locators, represented in the address input box of the browser. If a desired object is not identified by a representation in the address input box, it is not recorded or not definitively recorded, and indeed also cannot be appropriately added as a favorite. This history may thus incompletely define the state of the system, for example, when the system executes a script, applet or plugin, or other machine state not fully defined by the URL. In these cases, the history list is not usable to completely restore a prior state of the browser. [0009] A Uniform Resource Identifier (RFC 1630) is the name for the standard generic object in the World Wide Web. Internet space is inhabited by many points of content. A URI (Uniform Resource Identifier is the way you identify any of those points of content, whether it be a page of text, a video or sound clip, a still or animated image, or a program. The most common form of URI is the Web page address, which is a particular form or subset of URI called a Uniform Resource Locator (URL). A URI typically describes: the mechanism used to access the resource; the specific computer that the resource is housed in; and the specific name of the resource (a file name) on the computer. Another kind of URI is the Uniform Resource Name (URN). A URN is a form of URI that has “institutional persistence,” which means that its exact location may change from time to time, but some agency will be able to find it. [0010] In these known systems, only Web pages and downloaded elements are stored and recorded. In contrast, certain information, such as search queries that are not returned as part of a URL, as well as other arbitrary information selected by the user or server, cannot be included on the history list unless separately represented as a defined Web page. Thus, scriptlet and applet communications sessions may completely bypass the browser's ability to record the session progress, and thus make the browser unable to define the associated states and return to a prior state. [0011] A related problem occurs where the remote server employs cookies to define the Web page transmitted. If the cookie is changed, and indeed such changes may be made by the remote server during subsequent interaction, the state defined by the URL cannot be used to return the browser to the prior state. [0012] Cookies files stored in conjunction with user agents (web browsers, etc.) to hold small amounts of state information associated with a user's web browsing. Common applications for cookies include storing user preferences, automating low security user signon facilities, and helping collect data used for “shopping cart” style applications. See, RFC 2109, Network Working Group, HTTP State Management Mechanism. See, also RFC 2068, Network Working Group, Hypertext Transfer Protocol—HTTP/1.1 [0013] U.S. Pat. No. 6,018,344, expressly incorporated herein by reference, provides a system which, at a server, records requests for URLs by users, and provides a two dimensional map representing the usage history. U.S. Pat. No. 6,038,610, expressly incorporated herein by reference, provides a system and method for storage of site maps at respective servers, which are then communicated to client systems. [0014] Because of the limitations just discussed, among others, the implemented history list function employed by available browsers, i.e., standardized software executing on client systems for interacting with the Internet Web servers, fails to achieve the ability to return reliably the browser to a prior state in a number of common instances. [0015] In order to elucidate the problems involved in capturing the user's session history, it is necessary to consider the state of the client and server during a user session. In order to define the state of the machine, user activity is tracked. Storing a complete image of all processes, memory and registers is untenable, since literally this requires turning back the clock, with loss of all intervening information, which is either impossible or itself undesired. User activity may traditionally be tracked in a number of known ways. For example, a local computer application can track user activity. Likewise, any system interposed within a necessary communication path may also log user activity. A computer identifier, such as commonly included within a browser cookie, may be used to identify, and thus subsequently track the user, at a remote server. However, since the user may delete browser cookies, this technique is not reliable between sessions. In some cases, a communications address, such as an IP address, may be used to track a user; however, since users may share IP addresses, and IP addresses may be dynamically assigned, this technique is not globally reliable between communications sessions. SUMMARY AND OBJECTS OF THE INVENTION [0016] The present invention therefore seeks to provide improved human computer user interfaces, as well as supporting infrastructures. A particular problem confronting a user is an organization of information in a usage session or group of sessions. As a part of typical usage of an Internet system, users explore new content, through search engines, embedded hyperlinks, and the like. Often, the exploration is initially unfocused or noncommittal, as the user seeks to understand the field being searched. This initial exploration may include trial and error content review, as well as a comprehensive or exhaustive search of potentially relevant information. Typically, this exploration precedes normal and specific usage of the information, and thus the process invariably includes some degree of backtracking over previously reviewed information. [0017] The present invention thus provides enhanced methods for the identification, recall and organization of search paths and results. [0018] These are effected by improved methods of tracking, user activity, thus defining relevant states, and improved methods of presenting past user activity patterns, thus facilitating efficient usage thereof. [0019] In some cases, the exploration phase conducted by one user may be used to facilitate the search by another. Thus, the search path may be employed as an object that is employed by other users. [0020] These objects are created to record goal-directed behavior of the user, and may thus be relevant to other users having the same goals. Often, the goal is a more complex semantic concept than any single search represented within the set, and thus the identification of the goal may be a richer source of information regarding a user and the surrounding context than search queries. Once the goal is defined, an automated system may be provided to anticipate the user's requirements, which may then be presented to the user. Advantageously, when the detected or defined goal includes a transaction, an automated system is provided for presenting to the user transaction possibilities within the scope of the goal. Thus, for example, advertisements or other commercial information may be presented to the user. When the user's goal is non-transactional, the system may operate differently. For example, goal-related information from a variety of sources and general type advertisements may be directed to the user. [0021] Internet search engines and portals typically operate on a commercial subsidy model; this may include payment on a per-ad basis, a per-click-through basis, or a per-consummated transaction basis, for example. The use of targeting technology tends to favor transaction-biased models over ad-volume-based models. The present invention thus provides a capability for higher-level analysis of the user, at a goal rather than search query level. This technique may also be combined with user profiling, such that the status, context and history may be used to adaptively define the state of the system. See, U.S. Pat. No. 5,774,357, expressly incorporated herein by reference. [0022] The Internet's World Wide Web is typically considered a large set of Web pages that are aggregated into Web sites, with each Web site generally having a home page, from which other Web pages are accessible through hyperlinks. Normal use of the Web site may therefore entail multiple viewings of the home page. A diagram of normal usage therefore often appears like a hierarchal tree, with the home page at the root, other pages as branches, and potentially detailed pages or referenced database entries as leaves. Of course, embedded hyperlinks and other types of usage may complicate the diagram. [0023] Present browsers support “back” and “forward” functions, which allow a user to move through a historical list of visited Web pages to a referencing Web page (back), and referenced Web page (forward). However, where there is an ambiguity, the forward function provides the last visited page, and the back function provides a “higher level” referencing page. Thus, in a complex Web site, the back and forward functions may fail to provide full navigational capability. In short, history-of-use information is lost. [0024] The present invention addresses this problem by providing a “Session Mapping™” feature, in which one or more time lines are constructed from “history objects” that are, for example, each defined by a set of one or more Web pages visited by the user, and, potentially, activities performed by the user with respect to those Web pages. Thus, a user may return to a past-visited Web page by direct and random access thereof. This history object and related information, for example, may be stored as an information object at a server, and therefore, the user may potentially end his browser session without loss of the history context for that session. Likewise, this history object may be provided in editable format and further presented or transmitted to other users, allowing a sharing of a search experience, as well as a possible viral marketing advantage to the provider of the session mapping service or its sponsors. The history object may preferably also include a chronology, allowing a synchronized presentation of the history object, for example using Synchronized Multimedia Integration Language (SMIL) [Boston Specification (W3C Working Draft 3-August-1999; http://www.w3.org/1999/08/WD-smil-boston-19990803)]. [0025] Preferably, a history object is defined as a set of URLs, optionally with descriptive text, time, duration and/or number of accesses. This information is preferably presented with management and organizational tools for editing and organizing a set of history objects. The editing functions may include, for example, stripping of personal information from the URLs, for example where a user seeks to generalize the history object for third party use. Other functions may include deletion of certain steps or URLs, insertion of objects or URLs, appending and truncating sequences, saving and recalling, manual editing of command line entries and associated files, e.g., cookies, and archiving. Organizing functions include naming, renaming, ordering, deleting, copying, sending, receiving, sharing, privatizing, and “sanitizing” of history objects. The system may also provide a sanitizing function, for example, globally analyzing the URLs and associated objects to ensure that they do not contain personal information or private passwords (and if so, eliminating this information) and do not contain obscene or scandalous materials. This later analysis may include implementation of a (Mattel) Cyperpatrol-type filter along with semantic filtering. This filtering may encompass the history object itself, or require an analysis of the pages and objects referenced within the history object. [0026] A particular aspect of the present invention is that it allows a dynamic process to be defined. If a URL in the history object references a Web page whose underlying information changes, e.g., if the URL itself defines a search query on a database, and the contents of the database change, or the URL defines a dynamically defined object, then the subsequent access of the URL through the history object will represent the updated content. Thus, the history object may be used to define a set of content dynamically. [0027] On the other hand, sometimes a user seeks to define information statically as seen at a particular point in time. If the exact state of the URL is intended to be preserved, means may be established to cache the Web page content and reference the cached content rather than live Web page content, e.g., through an alias. This caching may be performed locally or through an external service. Typically, the history object will continue to appear to reference the source page (live) URL, although a hyperlink will direct recall of the cached copy. [0028] In still further instances, a user is interested in analyzing changes in the referenced Web pages. Therefore, both the cached and live versions of a Web page would be pertinent. Such analysis may also be performed locally, through a special application, or by corresponding application on a server. [0029] In some cases, the client computer request to the server does not correspond to a stateless. URL, and therefore the URL transmitted by the browser to the server would be insufficient to fully define the returned information. Rather, the returned information may relate to additional information, such as a sequence of events leading up to when the URL is transmitted to the server, or information defined by a cookie. The present invention, in fact, addresses both of these possibilities. With respect to the former, the history object directly addresses this issue by maintaining the sequence (path) by which a user achieves a given state of the system. With respect to the later, the present invention preferably encompasses a cookie manager, for example operating as an application within the client system, or on a remote server, which associates an appropriate cookie with each step within the history object, where necessary. Thus, the state of the cookie at the time of the original reference is preserved. As discussed above, according to one embodiment of the invention, the cookie manager resides within a server. In this case, the server acts as a third party proxy to the request. The client browser transmits URLs through the proxy server, and these URLs are modified as appropriate to achieve a desired state. In fact, a macro-sequence of URLs may be triggered to, define automatically a complex, path-dependent state with a single act by the user. Rather than acting as a complete proxy, requiring the proxy server to stand as an intermediary for all communications, the proxy server may spoof the client system's address (i.e., send a communication with a false IP address, causing the communicating partner to respond to redirect communications). It is noted that, while generally, spoofing is considered an undesirable security violation, in instances where the respective parties are aware and permissive of this activity, it may be an acceptable method. Alternatives to spoofing to achieve essentially the same results may be employed as well. Thus, in this asymmetric communication case, the proxy server selectively intercepts upstream communications and not the downstream communications. When the server downloads a cookie or applet to the client, this communication bypasses the proxy; however, the next time that modified cookie is uploaded, it passes through the proxy, and is captured at that time. [0030] It is noted that some of the functions implemented by the system according to the present invention are generally deemed to require security permissions or certifications. The user therefore will typically be requested to configure the security settings (or allow automatic reconfiguration by, or example, an applet) to permit system operation. The functionality gained from use of the system will, of course, provide sufficient benefit to the user to interest him in configuring the system (or allowing system reconfiguration) for such operation. Alternately, in most instances, the functions according to the present invention may also be implemented without requiring security setting reconfiguration, or in systems which do not support some of the functionality, such as scripts and applets. For example, displays may be presented as static web pages without scripts or applets, with necessary communication directly with the server or through a formal proxy server/application server. [0031] It is noted that this type of proxy may be present as a separate resource on the Internet or within a local area network. Furthermore, this proxy may be integrated with another proxy server, such as a firewall device. [0032] It is further noted that the cookie substitution and other aspects of the transaction need not be transparent to the proxy server; the information may be fully encrypted, since the proxy server acts in a content-neutral fashion. So long as the address information within each packet is open, and cookies are unambiguously identified, the proxy may perform its intended function. [0033] In order to allow this type of three-party communication, the content server system is preferably “fooled” into thinking that the communications are actually separate two-party streams. For example, the history object may form the basis of a communication to transmit a URL and possibly associated information, such as cookies, thus defining the desired state, to the proxy server. The proxy server then forwards the URL and optional cookie, each of which is possibly modified to achieve the desired state of the client system, to the content server. [0034] Correspondingly, the proxy server returns a simple redirect response to the client system, including an appropriate URL for the content server. The content server, in this case, responds to the spoofed (forged IP header) communication, effectively pushing the Web page to the client. The client system, in turn, since it has requested a URL from the content server via the redirect, sees the returned Web page as being the one requested, and accepts it. The proxy server function is therefore implemented without modification of the remote server, and with minimal modification of the client system (e.g., ensure security is set with permission to accept server-side redirect), and therefore maintains broad compatibility. [0035] The history object characteristics may be contained within an application or applet, including the desired functionality, and executed on the client system hardware. In this case, greater flexibility is available, but may result in certain incompatibilities. For example, the IP stack itself may be modified to implement the desired functions, which in this case would include a parallel transmission of packets to the remote server and history management server. Thus, a remote history management server would be assured a complete record of the transmitted information. Likewise, a local server may be provided proximate to the client system, through which the browser communicates. In this case, all transmitted and received URLs and Web pages may be managed locally. It is noted that an OCX (Microsoft ActiveX applet) may be able to perform these types of functions. [0036] A Session Mapping™ applet or scriptlet may also be provided on the client system to capture the URL information, which may then be stored or transmitted to a remote server. In this case, the Session Mapping™ applet or scriptlet typically does not have access to local operating system level functions, and cannot intercept or alter communications between the browser and stack, or stack and network interface. However, most common browsers do provide a function wherein the most recent URL is available for inspection. Thus, a Session Mapping™ applet or scriptlet may capture this information and convey it to a history management system. Likewise, cookies may be transmitted from the browser to remote servers when properly requested; thus, the appropriate cookies may also be communicated to the history management system. [0037] The Session Mapping™ applet according to the present invention is distinguished from the applet described in U.S. Pat. No. 6,035,332, expressly incorporated herein by reference, since the applet of U.S. Pat. No. 6,035,332 requires that the tracked Web page be served from a controlled or cooperating Web server, rather than any random Web server. It is also noted that the graphic user interface of U.S. Pat. No. 6,035,332 is dissimilar in key respects. [0038] A particular advantage of browser scripts is that no distinct download and installation is necessary. It is noted that some of the techniques described herein violate traditional security principles, and, but for the desirable functionality, might be considered intrusive. It is further noted that the techniques described herein may be used to implement functions other than history management. For example, a similar technique may be used to synchronize two or more client systems on the Internet; for each transaction, one system acts as a master, requesting a URL and also transmitting the URL and an optional cookie to a proxy site. At the proxy site, the URL is also requested, with the identical cookie available for upload. Thus, the states of the two (or more) systems will be synchronized. This technique would facilitate the sharing of a session experience on the Web with many other users. [0039] The techniques according to the present invention may also be used for remote logging and monitoring of users. [0040] According to the present invention, a Session Mapping™ applet may process a history object to recreate the original sequence (or a modification thereof), including an automatic sequencing of states. [0041] In performing a search, typically a large proportion of the pages visited will be irrelevant or secondary. For example, a user searching for jewelry may submit the search query “diamond” into a search engine. The search query URL is trapped by the Session Mapping™ applet or scriptlet and either processed locally or transmitted to the host site. The user is then typically presented with a list of Web pages (URLs) that correspond to the search query. Some of these URLs may contain content only, without opportunity for purchase, while others may include purchasing opportunities. Some responsive URLs may, in fact, be irrelevant or distasteful. Often, the user must explore the presented information in order to categorize the sites. In some instances, the user may search the topic using a variety of search terms or execute the same search query on a variety of search engines. [0042] After the user has completed a search and acquired background information, the next step is typically to employ that information gainfully. According to the prior art, the user was forced, using memory or rudimentary tools, to relocate the best sites from the search, which typically occurred before a complete analysis of the available information. This prospect often lead to a truncation of a search when a minimally-acceptable Web page or well-known site was identified, rather than facing the prospect of finding it again using inadequate tools. According to the present invention, the user is permitted to complete his search and investigation, with reasonable prospects of easily finding and retrieving any previously visited sites, including defined states thereof. [0043] As each Web page is visited, it is added to a list, and preferably maintained and presented in a “Personal Services Infrastructure”™ (PSI™) format, which is displayed on the screen generated by a browser and/or applet. For example, this information is presented in a marginal frame of a browser, or within a visually presented applet. Therefore, when the user seeks to retrace his steps, each significant hop or state is separately listed, possibly including additional descriptive information, such as the duration of content viewing, the time(s) of viewing, and the like (the duration of a visit being, among other things, a key indicator of value for the user). Furthermore, each entry may be provided with certain editing features, for example, the URL, description and order may be edited. [0044] In defining a state of the client's session, a number of options are available. Commonly, each Web site is accessed through a special Web page called a home page. Often the Web site home page is associated with an Internet Top Level Domain name (TLD), or domain name, such as WWW.MYSITE.COM. Therefore, the membership of web sites is often classified based on the associated domain name. Other methods are available, however, to determine membership within a Web site. According to one embodiment of the invention, each Web site is provided with a separate region within a Session Map™. When the user selects a respective region of the Session Map™, the chronological path of the user within that Web site may be expanded, possibly with a hierarchal representation of the organization of the site (or limited to pages hyperlinked by the user), or to a linear session map opening from within the segment of the session map. Of course, the user may traverse a path that seamlessly traverses a number of TLDs or Web sites, so that this distinction may be arbitrary. Thus, other modes of presentation may be offered to the user, based on the stored information and possibly an analysis of the Web page content referred to thereby. Another organizational method relates to the amount of time that a user dwelled on a web page, or composite set of pages, e.g., a site; the longer the dwell, the higher the implied importance. A further organizational principle involves analyzing the use of a Web page as a hub; if the user returns to a page a number of times in the course of an activity, that page is considered an important hub, with Web pages traversed thereby considered spokes. This analysis, it is noted, does not require that the TLD be the same for the hub and spokes. [0045] Another organizational principle seeks to employ Web page expiry data. Typically, a static home page will not expire, while dynamically generated pages quickly expire. Pages that have associated ID numbers (or alphanumeric sequences) typically result from a sequence of actions, wherein the user session, is initiated and tracked by means of the ID number. In order to recreate the state of the system, the series of URLs and forms which lead to the desired URL must be replicated, allowing the ID number to change according to the newly recreated sequence. Thus, the history object is processed by an application to parse URLs and construct synthetic URLs representing the desired states, without forcing the user to track manually the prior actions. In this case, when a user selects a Web page that requires a series of interactions to recall from the server, this series of interactions is automatically invoked from a logical starting point. In representing this to the user, it is the lower level Web pages within a hierarchy that take on greater importance, with the higher level Web pages serving merely as conduits. Thus, if the history display is collapsed, it is the end Web page that is represented, and the path toward that Web page becomes unveiled only when the user specifically selects the end Web page. [0046] In this regard, the history of use may be represented as a set of chains, with the top and/or bottom of each chain defining a relevant feature or identifier, and the intervening portions having presumed lower importance. Each node within the chain may be represented by a separate history object. Thus, a two dimensional data set may advantageously be normally represented as a one dimensional “time line,” preferably with only one hierarchal chain visible at a time, and otherwise merely with an identification of the chain available for access by the user. [0047] An example where the highest level is relevant to the user is, for example, at a corporate Web site, where a user is investigating various aspects of the company. The home page is therefore an appropriate starting point and identifier for the string of events. [0048] On the other hand, an example where the highest level is not relevant is where the user is searching a set of content through a portal. In this case, the identification of the portal is nearly irrelevant. The search query, however, defines the data set, with the retrieved and inspected URLs or Web pages encompassing the relevant material. Thus, the string is preferably defined by the search query. [0049] The present invention provides a procedure that records in detail a history of a search, notwithstanding that a respective search engine does not or cannot do so itself. The present invention therefore seeks to trap or capture detailed information about the path taken by the user in completing a task, including scriptlet and applet usage, regardless of which search engine or server is accessed for information, and preferably allows a standard browser to be employed. [0050] According to a preferred embodiment of the invention, the history is provided for each session, and extends for the duration of the session. The history is preferably presented as a time line extending horizontally, which may be scrolled horizontally or which is wrapped in successive rows, as the listed history exceeds the column width. Preferably, the time line also captures the beginning and end time of each state, or the duration, or both. The time-line entry for each page or step may be annotated or provided with descriptive text, which may be provided by a history object, automatically generated from the history object, or manually associated with the history object. Preferably, the time line information includes details sufficient for the user to understand the nature of the transition between successive history objects. Preferably, also, the time-line is searchable by text or by characteristic, such as URL, title, date, time. [0051] According to the present invention, this presented history need not encompass a literal record of the path taken by the user, but may, in fact, include information derived from a variety of sources. First, the information list may be enhanced to include advertisements or marketing information. This information is preferably derived either from a user profile, and predicted to be relevant to the user based thereon, or from the search context, and thus related to the information included within the history. Therefore, it is apparent that a presented history bar, including history objects and supplemental commercial objects, may be a source of commercial subsidy. By linking the commercial subsidy with a useful feature, consumer acceptance thereof may be enhanced. [0052] The information may also be enhanced by analysis and presentation of additional content, distinct from the actual history. In some cases, this enhanced information may be identical to the advertisements; thus, where a user is seeking to make a purchase, and the search is for relevant vendors, the enhanced information is an advertisement of the type sought by the user. In other instances, the advertisements are of a general nature. Additionally or alternatively to advertising information, other enhanced information may be provided. For example, hints or suggestions, motivational messages, or other information may be automatically or manually inserted. [0053] In some instances, the system is not supported by commercial subsidy. Therefore, the enhanced information presented may take the form, for example, of goal directed enhanced information or status information. [0054] The graphic display objects according to the present invention may also include user interface functions for performing complex tasks or URL references. Thus, in contrast to prior systems presenting a user history as a set of URLs accessed by the user, the present invention provides enhancements to the accessible functionality with respect to identifications of past activities. [0055] Typical functionality which may be made available, as appropriate, include “summarize page,” “find like sites,” “add to favorites,” and “add to shopping cart,” “vote on value of site (or product),” “see others' votes,” “make a note,” “see other users' notes,” or an omnibus service icon or control that brings up a group of choices. [0056] It is therefore an object of the invention to provide an apparatus, comprising means for automatically tracking a URL path of a user; and means for displaying the URL path of the user. [0057] It is a further object of the invention to provide a human computer interface enhancement for an object browser, each object having an object resource locator, comprising means for automatically logging an object resource locator traversal history by the user; and a software construct, executable for defining a display pane in conjunction with the browser, said display pane comprising a set of hyperlinks and associated human-readable tags for object resource locators. [0058] It is a still further object of the invention to provide a history display system, comprising means for automatically storing a history of object references by a user; means for editing, by the user, the stored history; and means for display of the history, wherein said display hyperlinks to the referenced objects to allow arbitrary selection of an object. [0059] It is another object of the invention to provide a history display system, comprising means for automatically storing a history of states induced by a user; means for editing, by the user, the stored history; and means for display of the history, wherein said display hyperlinks to the referenced states to allow arbitrary selection of a historical state. The display hyperlinks are preferably displayed linearly, in chronological order. The display hyperlinks may also be displayed in hierarchal order, and may include importance-weighting information. [0060] It is a further object of the invention to provide a method of trapping URL references in an unmodified Web browser, comprising the steps of providing an applet executing in association with the Web browser, storing a current URL as a favorite within the browser, and capturing a last saved favorite URL from a favorites list. [0061] It is a still further object of the invention to provide a method of trapping URL references in an unmodified Web browser supporting frames, comprising the steps of loading a Web page from a cooperative server in a first frame; identifying a desired URL with the browser to request an Internet resource in a second frame, providing a script in the first frame to capture the identified URL in the second frame and transmit it to the cooperative server, and downloading, from the cooperative server to the Web browser first frame, a sequence of identified URLs. BRIEF DESCRIPTION OF THE DRAWINGS [0062] The purpose and advantages of the invention will be apparent to those skilled in the art from the following detailed description in conjunction with the appended drawings, in which: [0063] FIGS. 1A 1 E show sequential states of a history display applet; and [0064] FIG. 2 shows a Web browser user interface. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Example 1 [0065] A first embodiment of the invention provides a system which operates in conjunction with a modern Web-enabled computer system with a standard browser installed. For example, a so-called WinTel (Intel Pentium III Processor, executing Microsoft Windows 9X or NT/2000 software) standard personal computer and either Netscape Navigator or Microsoft Internet Explorer, both of which are JavaScript and Java enabled, and frames-capable. Alternately, an Internet appliance platform (e.g., designed specifically for Internet usage rather than general purpose home or office tasks) may be employed. The system communicates with a remote server which is provided as discussed herein. [0066] A particular aspect of this embodiment of the invention is that enhanced features are provided for a standard browser system by means that do not require use of non-standard browsers, a special installation procedure or a computer reboot. Thus, the system provides broad compatibility, platform independence, portability, and a low probability of causing conflicts, system bugs or instabilities. The server-side hardware technology is also standard, while the server application software is custom. [0067] By operating within frames, the browser permits two Web pages to be displayed simultaneously and to be interactive. This communication or interactivity occurs within the browser and generally is subject to certain security controls. Accordingly, certain security measures that seek to limit inter process communications and preemption must be disabled. [0068] FIGS. 1A 1 E show a sequence of Session Maps™, generated by an applet executing within the user's web browser. In the Session Maps™, a user's progressive search on the Web for a diamond ring merchant is traced. Each frame represents a step, and any previous step can be returned in one click by treating that frame as a hyper-link. In the first step, shown in FIG. 1A , the user is represented at the home page, “Double Agent”. In the second frame, shown in FIG. 1B , the user accesses the “Double Agent” support page. In the third frame, shown in FIG. 1C , the search query itself, “diamonds,” is captured. In the fourth frame, shown in FIG. 1D , the user selects a taxonomic class, “jewelry” (which is distinct from, for example, baseball, industrial, and graphic images involving the same word). The fifth frame, shown in FIG. 1E , captures user's finding of a relevant Web page, “Diamond Depot.” The icons in the fifth frame represent a set of single-click services available to the user, with respect to the represented Web page. These services include “find like sites,” “save to favorites,” and “add to shopping cart,” which are represented as icons within a respective frame, where appropriate, and “summarize page,” represented by an icon external to each frame within the chain. For example, the shopping cart is available only for Web pages compliant with a shopping cart standard associated with the system, while the find like sites, save to favorites and summarize page are available for Web pages in general. Other possible services available to be offered through icons associated with the segments of the session map include: make an annotation; see other user's annotations or comments; vote on the worth of a site; see others' votes; see review information; compare price; see address, phone, e-mail and/or other contact information about a web site. [0069] In practice, the user calls up a URL 1 in the browser 10 from a cooperative remote server which provides a pair of frames; a first frame 3 a controlled by the cooperative remote server, having an associated executable software construct, e.g., JavaScript, and a second frame 3 b for display and manipulation of content. The user, within the second frame 3 b or in the address bar, identifies a desired URL 1 , for example by typing or hyperlinking. The JavaScript construct captures the URL 1 , which is then transmitted to the cooperative remote server. [0070] The cooperative remote server then uses the acquired URL 1 , which is transmitted in a form that identifies the browser system or user thereof, to construct a history of use for the session, called herein a Session Map™. The history of use is then transmitted back to the first frame 3 a , and displayed for the user, including a set of hyperlinks, each defining a respective prior state of the system and allowing return thereto. [0071] The history of use is preferably displayed with a second JavaScript construct, in the form of a time line 4 , for example disposed horizontally at the bottom of the screen. The remote server analyzes historical sequences in order to define goal-directed behavior sets and to segregate distinct goals. This segregation is based on conceptual factors, such as the relation of sequential URLs, e.g., hierarchal relation within a Web site or file storage system, time spent at particular Web pages or web sites, hiatus between uses or activity, semantic analysis or search queries or Web pages, as well as layout issues, such as an optimum number of displayed behavior sets, e.g., five displayed horizontally across the screen, complexity of each behavior set, and the like. [0072] The conceptual analysis may also seek to separate mixed concepts. For example, a user might be conducting two or more searches simultaneously, which may be related or unrelated. If these are related, the desired Session Map™ consolidates the histories and resolves ambiguities or artifacts. If these are unrelated, the desired Session Map™ isolates the trails, either as separate goal directed behaviors in the displayed linear sequence, or as a separate time line sequence. [0073] Each goal directed behavior identified in the time line display represents one or more states of the browser. If the number of goal directed behaviors exceeds the display space, then the display applet may provide scroll functions. Alternately, the display may be provided within a frame, with scrolling supported by the browser and/or operating system. [0074] The remote server seeks to provide, for each set of states, a semantic description thereof. In some cases, a graphic or acoustic description or label is preferred. Therefore, the present embodiment may support flexible labeling, including text, icon, thumbnail graphic, sound clip, or the like. The remote server may derive these labels by first, an analysis of the URLs, to determine whether the URL conveys a useful semantic label. For example, in many cases, a search engine query is a part of the URL and is descriptive the content of the Web page, as well as the associated set of Web pages. In other instances, the URL will be uninformative. In that case, the remote server may request the page, and perform an analysis thereof, to generate a summary or topical statement (or, if appropriate, musical clip, icon or thumbnail). The result of the analysis is transmitted to the browser, for display associated with a hyperlink. When the user selects the hyperlink, the entire associated chronological string is revealed. This string may be stored internally within the browser, or downloaded from the server. According to one embodiment, the search history is presented as a hierarchal tree, with each node of the tree representing a URL, and being hyperlinked thereto. Example 2 [0075] The present invention provides a set of Mini Agent™ functions that may be associated with objects, for example representing web pages or web sites. These are described with respect to FIG. 2 . [0076] A first Mini Agent™ function, providing a summarize page function, is accessed by selecting a hyperlink icon 11 associated with a history object representing a Web page. The icon 11 , for example, shows a script lower case serif “i”, representing “information”. The hyperlink, in turn, includes an identification, e.g., URL, of the Web page, which is passed to a summarizer server. The summarizer server receives the URL, and accesses a database, to determine whether an existing summary exists for the URL. If so, this is returned to the user. If not, the summarizer accesses the URL, and performs a semantic (or other content-dependent) analysis of the corresponding Web page, and optionally objects incorporated into the Web page. As a result of the semantic or other content-dependent analysis, a brief message is passed to the user, providing a Web page summary. A preferable semantic analysis analyzes the Web page text to parse context-defining words or phrases, of which many web pages have few, and transmits these parsed words and phrases to the user. An editor may also analyze Web pages and, for example, store manually generated summaries in the database. [0077] A second Mini Agent™ serves to “find like sites”. This is represented by an icon 12 corresponding to the mathematical equivalence symbol. Like the summarize page function, the function is accessed by selecting a hyperlink icon associated with a history object representing a Web page. The hyperlink, in turn, includes an identification, e.g., URL, of the Web page, which is passed to a similar site server. The similar site server receives the URL, and accesses a database, to determine whether an existing record, defining a set of similar sites, exists for the URL. If so, this is returned to the user. If not, the similar site server accesses the URL, and performs a content-dependent analysis of the corresponding Web page, and optionally objects incorporated into the Web page. As a result of the content-dependent analysis, a query, for example a Boolean query or other query type, is passed to an Internet search engine. [0078] Alternately, the classification of the Web page within a taxonomic hierarchy may be determined, the similar pages being defined as those that are similarly classified. The resulting list of similar sites is passed to the user. A human editor may also analyze commonly visited Web pages and, for example, store manually generated sets of similar sites in the database. Likewise, a collaborative filter may be employed to provide “similar” pages based on a probability of being accessed temporally proximate in time to the respective Web page by a group of persons. [0079] A third Mini Agent™ is “add to favorites”. This is represented by a thumb-tack icon 13 . In this case, the function does not represent a URL, but rather a script applet which executes within the browser to add the respective URL of the associated web page to the favorites list maintained by the browser. This script is typically defined distinctly for each history object. [0080] A fourth Mini Agent™ is “add to shopping cart”. This is represented by an “S” icon 14 . An electronic shopping cart is an electronic store, associated with an individual user, identifying objects for purchase. In this case, the implementation is in some sense similar to that described in U.S. Pat. No. 5,960,411 (Hartman, et al., Sep. 28, 1999), expressly incorporated herein by reference, although the functionality differs. This function may be implemented in two ways. First, the hyperlink may invoke an applet, and indeed may have a context sensitive functionality, i.e., the icon representing the function will vary depending on the Web page or content thereof, or the status of the Web page and/or user system. Second, the existing shopping cart hyperlink from the referenced Web page may be copied or emulated as the hyperlink associated with the icon, and therefore a selection of the icon representing “add to shopping cart” will have the same effect as a selection of that hyperlink from within the Web page itself. [0081] The “add to shopping cart” functionality may be limited to compliant Web sites, providing special support for this functionality, or be available to all sites that have an accessible shopping cart function. [0082] For example, a Web page identified by a URL represents a description of a single item available for purchase. The user, in the midst of a search for the item, may not be ready to consummate a sale, and thus may not wish to place the object in a “shopping cart”. Rather, only after a search is complete will a user identify the item and most preferable vendor. [0083] Using the “add to shopping cart” icon, the user may, without reopening the web page, directly add the item to a shopping cart, which indeed the shopping cart may be consolidated for a number of vendors and/or different that the shopping cart normally provided for user of the Web site. At a later point in time, the user may then “check out”, or provide transactional details to close the purchase for objects in the shopping cart. [0084] The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are, therefore, intended to be embraced therein. The term “comprising”, as used herein, shall be interpreted as including, but not limited to inclusion of other elements not inconsistent with the structures and/or functions of the other elements recited.

A system and method for tracking a user history, for presentation thereof within a browser display. An executable software construct operates at a client machine to trap object references, which are then transmitted to a server. The server analyzes the object references and organizes them into a display structure. The display structure is then displayed within the browser, including hyperlinks to allow the user to select a prior system state to which he seeks to return. Preferably, the software construct also manages objects associated with the object reference, for example cookies associated with URLs, in order to assure full definition of the desired state. The display structure may also be provided to browsers distinct from the originating browser.

[0001] This application claims the benefit of the Korean Application No. P2001-10321 filed on Feb. 28, 2001, which is hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a method for controlling a memory in a digital system. [0004] 2. Background of the Related Art [0005] In embedded systems developed recently, there are ones that require processing and managing of a large amount of data. For an example, the digital system, such as a digital TV receiver, employs a web data used in a computer environment, or a data received from, and required for broadcasting, or an additional data. Recently, a broadcasting for transmission of data is under preparation. [0006] A current data base system developed and used for more convenient and effective processing of a large amount of data uses disks for recording data, and uses techniques of transaction management, query handling, synchronism control, indexing, hashing, and the like. [0007] Moreover, though a main memory resident type data base system that is made possible by development of a memory size also has a main data base on the memory, in most of the cases, the main memory resident type data base system is based on disks which can back up the main data base. The system having such a disk makes no assumption of a limitation of a maximum storage capacity of data. [0008] However, the case is limited, in which the disk is based in the embedded system actually, and, though memory technologies are developing currently, a system only having the memory is required to assume very limited use of the memory in comparison to a disk, to require a system that manage data in the system only having a limited memory. [0009] Moreover, though it does not matters for a system having an amount of data fixed in advance required to be stored in the system, there can be a storage demand greater than a memory size capable to store in a system the data is kept added, erased, and queried because a maximum required storage capacity is not fixed. SUMMARY OF THE INVENTION [0010] Accordingly, the present invention is directed to a method for controlling a memory in a digital system that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. [0011] An object of the present invention is to provide a method for controlling a memory in a digital system having a limited size of memory, which can minimized a system performance deterioration, and facilitates storage of data greater than the limited capacity of the memory, [0012] Another object of the present invention is to provide a method for controlling a memory in a digital system, which has advantages of the present data base system, such as avoidance of duplication of data, and an easy access to a data, and the like. [0013] Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. [0014] To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the method for controlling a memory in a digital system includes the steps of (a) dividing the memory into a plurality of fixed sized memory blocks, (b) defining at least one of the memory blocks as a region for compression/decompression, (c) assigning compression priorities to rest of the memory blocks except the memory blocks defined as region for compression/decompression, and (d) making the memory blocks to deal with an external data received according to an external command, and carrying out compression/decompression of data required in the dealing with the external data according to the compression priorities. [0015] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS [0016] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention: [0017] In the drawings: [0018] [0018]FIG. 1 illustrates a block diagram showing a system of a digital TV receiver in accordance with a preferred embodiment of the present invention; [0019] [0019]FIG. 2 illustrates a flow chart showing the steps of a process for controlling a memory in a digital system in accordance with a preferred embodiment of the present invention; [0020] [0020]FIG. 3 illustrates a flow chart showing the steps of a process for inserting a data in a memory in a digital system in accordance with a preferred embodiment of the present invention; [0021] [0021]FIG. 4 illustrates a flow chart showing the steps of a process for erasing a data from a memory in a digital system in accordance with a preferred embodiment of the present invention; [0022] [0022]FIG. 5 illustrates a flow chart showing the steps of a process for up-dating a data stored in a memory in a digital system in accordance with a preferred embodiment of the present invention; and, [0023] [0023]FIG. 6 illustrates a flow chart showing the steps of a process for reading a data stored in a memory in a digital system in accordance with a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0024] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In this embodiment, a digital TV receiver is taken into account among the digital systems. FIG. 1 illustrates a block diagram showing a system of a digital TV receiver in accordance with a preferred embodiment of the present invention. [0025] Referring to FIG. 1, the digital TV receiver includes a tuner 10 for receiving a digital broadcasting signal, a TP (transport) signal analyzer 20 for analyzing a TP signal from the digital broadcasting signal, to detect an audio signal and a video signal, a separator 30 for separating, and respectively decoding the audio signal and the video signal detected at the TP signal analyzer 20 , a decoder 40 for decoding the audio signal and the video signal decoded at the separator 30 , and a microcomputer 50 for controlling parts of the TV receivers. [0026] The microcomputer 50 divides channel data, program data, and information data received through the tuner 10 into fixed size blocks, stores in the memory 90 , and manages the stored data blocks. [0027] The digital TV receiver also includes an OSD (On Screen Display) processor 70 for providing an OSD text, and a display 80 for selectively superimposing the audio signal and the video signal decoded at the decoder 40 with the OSD text from the OSD processor 70 , and displaying on a screen. [0028] The microcomputer 50 in the digital TV receiver includes a storage managing module 51 for storing all the data from the tuner 10 in forms of data blocks by indexing or hashing, and carrying out a function to find a desired block from the stored data blocks quickly, a request processing module 52 for facilitating storage of a desired data in the memory 90 , or erasing or finding the desired data from the memory, a synchronism control module 53 for processing various requests on the sane time, and a memory managing module 54 for managing the memory 90 with the memory 90 divided into same sized blocks. [0029] The operation of the digital TV receiver of the present invention will be explained with reference to the attached drawings in detail. FIG. 2 illustrates a flow char showing the steps of a process for controlling a memory in a digital TV receiver in accordance with a preferred embodiment of the present invention, [0030] Referring to FIG. 2, the memory managing module 54 in the microcomputer 50 divides the memory 90 , to be used as a storage space, into fixed size blocks. Then, memory managing module 54 combines at least one of the memory blocks and designates as a compression/decompression region for temporary storage of a compressed data, or compressing a data. [0031] The memory managing module 54 records a number of access times to the data in each memory block, and measures an access frequency of the memory block based on the number of access times. The memory managing module 54 sets up priorities of compression of the memory blocks based on the access frequency for compressing data when a capacity of the memory 90 lacks. The lower the frequency of access, the higher the compression priority, Then, the microcomputer processes the received data. [0032] The data processing includes data insertion, data erasure, data up-dating, and data read. The steps of the data processing will be explained with reference to the attached drawings. FIG. 3 illustrates a flow chart showing the steps of a process for inserting a data in a memory in a digital system in accordance with a preferred embodiment of the present invention. [0033] Referring to FIG. 3, as explained, after the microcomputer 50 divides the memory 90 into a plurality of fixed size memory blocks according to the process shown in FIG. 2, the microcomputer 50 designates at least one of the memory blocks as the compression/decompression region. [0034] Then, the microcomputer 50 assigns the priorities of compression to rest of fixed size memory blocks except the compression/decompression region. It is determined if the memory 90 has an empty memory space for the data to be inserted. [0035] As a result of the comparison, it is known that there is no space in the memory 90 for receiving a data to be inserted therein even after all the memory blocks are compressed, the microcomputer 50 proceeds to an error processing state. Opposite to this, if there is an empty memory block or blocks as large as the data to be inserted, the data is inserted in the empty memory block or blocks of the memory 90 . [0036] Then, upon completion of insertion of the data, the microcomputer 50 compares a number of the empty memory blocks remained presently to a preset threshold value (a number of minimum memory blocks required). As a result of the comparison, if the preset threshold value is smaller than the number of empty memory blocks, the process for inserting a data is finished. [0037] Opposite to this, if the preset threshold value is greater than the number of empty memory blocks, the microcomputer 50 selects a memory block to be compressed presently from remained memory blocks according o the priorities of compression. [0038] The step for selecting the memory block to be compressed is started with reference to the compression priorities from a moment when use of a last memory block available for the data insertion is started, or the preset threshold value is exceeded. [0039] Then, the microcomputer 50 transfers the data in the memory block selected for the compression to the compression/decompression region, and compresses the data. The data in the selected memory block under compression can be accessed normally. [0040] The data in the compressed memory block is stored at other designated location of the memory 90 provided for the compressed memory block, and the compressed memory block is defined as an empty memory block by the microcomputer 50 . [0041] References representing the data in the compressed memory block are changed to a first starting address of the compressed memory block. Accordingly, when it is intended to make an indirect access to the data in the compressed memory block, the microcomputer 50 is required to determine the memory block under access presently is a compressed memory block. [0042] If it is determined that the memory block under access presently is a compressed memory block, the microcomputer 50 decompresses the compressed memory block in the compression/decompression region, and reads the decompressed memory block. [0043] [0043]FIG. 4 illustrates a flow chart showing the steps of a process for erasing a data from a memory in a digital TV receiver in accordance with a preferred embodiment of the present invention. [0044] Referring to FIG. 4, the microcomputer 50 divides the memory 90 into fixed sized memory blocks according to the process in FIG. 2. The microcomputer 50 defines at least one of the memory blocks as a compression/decompression region. Then, the microcomputer 50 assigns to a memory block each having a compression priority set up according to a frequency of access. [0045] The microcomputer 50 determines the data intended to erase is a data stored in the compression/decompression region. As a result of the determination, if it is determined that the data intended to erase is a data, not in the compression/decompression region, but in the memory blocks, the data is erased. [0046] Opposite to this, as a result of the determination, if it is determined that the data intended to erase is a data in the compression/decompression region, the microcomputer 50 calculates a size of memory occupied by the data to be erased in respective data blocks in the compression/decompression region. [0047] That is, if the occupied memory size is large, the microcomputer 50 determines that the memory in the block having the data erased therefrom has most of the memory left as a room space, and if the occupied memory size is small, the microcomputer 50 determines that the memory in the block having the data erased therefrom has many other data still stored in the memory block even if the data to be erased is erased. [0048] Therefore, the microcomputer 50 compares the occupied memory size in the memory block in the compression/decompression region and the threshold occupied memory size. [0049] As a result of the comparison, the occupied memory size calculated for each of the memory blocks is smaller than the threshold occupied memory size, the microcomputer 50 erases the compressed data and finishes the erasing process. Opposite to this, if the occupied memory size for each of the memory blocks is larger than the threshold occupied memory size, the microcomputer 50 decompresses the data. [0050] In this instance, referring to FIG. 4, before decompression of the compressed memory, i.e., compressed memory block, the microcomputer 50 compares a number of empty memory blocks in the memory 90 to the threshold value of empty memory blocks. Only when the number of empty memory blocks are greater than the threshold value of empty memory blocks, i.e., only when room of the memory is adequate, the microcomputer 50 decompresses the compressed data. In this instance, as explained, the data in the memory block can be accessed normally until the erasing process is finished completely. [0051] When the memory block is decompressed other memory block can also be decompressed by the microcomputer 50 . [0052] [0052]FIG. 5 illustrates a flow chart showing the steps of a process for up-dating a data stored in a memory in a digital TV receiver in accordance with a preferred embodiment of the present invention. [0053] Referring to FIG. 5, the microcomputer 50 divides the memory 90 into fixed sized memory blocks according to the process in FIG. 2, The microcomputer 50 defines at least one of the memory blocks as a compression/decompression region. Then, the microcomputer 50 assigns memory blocks each having a compression priority set up according to a frequency of access. [0054] The microcomputer 50 determines whether the data to be updated is stored in the compression/decompression region, or in the memory block. As a result of the determination, if it is determined that the data to be updated is stored in the memory blocks, the data is updated. [0055] As a result of the determination, if it is determined that the data to be updated is stored in the compression/decompression region, the microcomputer 50 determines a type of the data to be updated is of a variable size type or not. [0056] As a result of the determination, if the data to be updated is not the variable size type, the microcomputer 50 decompresses the compressed memory block temporarily, and updates the data to be updated. That is, when a fixed size data, with a fixed total size, is updated, the microcomputer 50 decompresses the compressed memory block, updates the data, and compresses the updated data. [0057] On the other hand, as a result of the determination, if the data to be updated is the variable size type, the microcomputer 50 assigns a new memory block and updates the data to be updated. The microcomputer 50 erases the existing data. The updating process has the inserting process explained in FIG. 3 and the erasing process explained in FIG. 4. [0058] [0058]FIG. 6 illustrates a flow chart showing the steps of a process for reading a data stored in a memory in a digital TV receiver in accordance with a preferred embodiment of the present invention. [0059] Referring to FIG. 6, the microcomputer 50 divides the memory 90 into fixed sized memory blocks according to the process in FIG. 2. The microcomputer 50 defines at least one of the memory blocks as a compression/decompression region. Then, the microcomputer 50 assigns to memory blocks each having a compression priority set up according to a frequency of access. [0060] The microcomputer 50 determines whether the data to be read is stored in the compression/decompression region. As a result of the determination, if it is determined that the data to be read is stored in one of the memory blocks, the microcomputer 50 reads the data. [0061] On the other hand, as a result of the determination, if the data to be read is stored in the compression/decompression region, the microcomputer decompresses the memory block having the data to be read stored therein temporarily and reads the data. [0062] As explained, the microcomputer 50 is programmed such that an access to the memory block is possible when the memory block is compressed/decompressed during the time the microcomputer 50 processes the data in the memory block, such as insertion, erasure, updating, and reading. [0063] In this instance, it is required that access to a data stored in a memory block is possible during the data is compressed/decompressed. Therefore, it is required that a final address of a compressed memory is fixed after compression of the memory block is finished completely, and the memory block under compression is valid until all the references indirectly indicating the data in the compressed memory block are revised. [0064] Opposite to this, it is also required that a compressed memory block is valid until the compressed memory block is decompressed into a general memory block, and all the references indicating the data in the general memory block is restored into original values before compression. [0065] An has been explained, the method for controlling a memory in a digital TV receiver of the present invention has the following advantages. [0066] First, the division of a data into a plurality of storage units in managing the data, and the partial compression of the data permits reduce a system performance deterioration and storage of more data when it is required to store collected data in a limited memory size. [0067] Second, the system does not come into an error state, but remains operative even if an allocated memory capacity lacks due to continuous addition of data and the like. [0068] Third, the division of a memory into fixed sized memory blocks and compression of a part of the memory blocks permits to reduce an overall data processing time period required to process entire system. [0069] It will be apparent to those skilled in the art that various modifications and variations can be made in the method for controlling a memory in a digital system of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Method for controlling a memory in a digital system, including the steps of (a) dividing the memory into a plurality of fixed sized memory blocks, (b) defining at least one of the memory blocks as a compression/decompression region, (c) assigning compression priorities to rest of the memory blocks except the memory blocks defined as the compression/decompression region, and (d) making the memory blocks to deal with an external data received according to an external command, and carrying out compression/decompression of data required in the dealing with the external data at the compression/decompression region according to the compression priorities.

CROSS-REFERENCE TO RELATED APPLICATIONS The following U.S. applications were filed on Jan. 16, 1984 and assigned to the same assignees as this application: T. S. Rzeszewski 2, "Single Sideband Modulated Chrominance Information for Compatible High-Definition Definition Television", Ser. No. 571,117; and T. S. Rzeszewski 3, "Time Multiplexing Chrominance Information for Compatible High-Definition Television", Ser. No. 571,183. The following U.S. application was filed on Jan. 28, 1983, and assigned to the same assignees as this application: T. S. Rzeszewski 1, "Fully Compatible High-Definition Television", Ser. No. 462,065. TECHNICAL FIELD This invention relates to a system for improving television picture quality and particularly to encoding and decoding facilities for use in a system that provides an improved aspect ratio to specially designed receivers and a signal of usual quality to conventional receivers without alteration. BACKGROUND OF THE INVENTION Within the television (TV) industry, aspect ratio is defined to be the ratio of the width of a picture to its height. In the present United States television picture as specified by the National Television Standards Committee (NTSC), the aspect ratio is 4 to 3. A motion picture screen in a commercial theater has an aspect ratio of at least 5 to 3. Studies have shown that the present NTSC television picture aspect ratio of 4 to 3 is not desirable from a human factors point of view for certain types of production techniques. For example, the article entitled "High-Definition Wide-Screen Television System for the Future", Takashi Fujio, IEEE Transactions On Broadcasting, Vol. BC-26, No. 4, Dec. 1980, pp. 113-124, indicates that the 5 to 3 aspect ratio is desirable for a television picture. The desirability of a larger aspect ratio than the present NTSC becomes much more important when the resolution of the picture is increased. The higher resolution picture allows scenes to be displayed at a distance rather than only close up while still retaining picture detail. Since many production techniques can make advantageous use of a wider screen for displaying scenes at a distance, the need for a larger aspect ratio arises. However, it has long been recognized that the human eye tends to focus on the center of a screen and is not conscious of the edges. Hence, the same degree of resolution is not needed at the edge of a picture as required at the center. An approach to providing high-definition television that could be received as a conventional television picture by conventional television receivers operating according to the NTSC standard or that could be received as a high-definition television picture by newly designed receivers without requiring prohibitively large amounts of bandwidth is disclosed in the above-identified application of T. S. Rzeszewski 1, "Fully Compatible High-Definition Television", Ser. No. 462,065. In that system, one television channel carries the conventional information while high-frequency luminance and high-frequency chrominance information are provided in a second television channel. That system has an aspect ratio of 4 to 3. Whereas, for many applications the aspect ratio of 4 to 3 is suitable, there exist applications for which a greater aspect ratio is desirable. Therefore, there exists a need for a high-definition television system that is compatible with the standard NTSC system but that can also provide improved aspect ratio information without requiring a greater bandwidth than that provided by two television channels. SUMMARY OF THE INVENTION The foregoing problems are solved and a technical advance is achieved in accordance with the principles of this invention incorporated in an illustrative method and structural embodiment in which high-definition television picture signals with improved aspect ratio information are provided that can be received on conventional unmodified television sets and that can be received on modified receivers by the utilization of two conventional broadcast television channels. The conventional television signal is transmitted in one channel, and the other channel communicates the high-frequency luminance and chrominance information. Advantageously, the additional aspect ratio information is transmitted during the horizontal retrace interval of the other television channel relying on the conventional television channel to provide horizontal synchronization information for both television channels. Advantageously, a television receiver designed in accordance with our invention decodes the conventional luminance and chrominance information using standard techniques and is responsive to the high-frequency luminance and chrominance information in the other channel to also decode that information. In addition, that receiver is responsive to the extended aspect ratio information transmitted during the horizontal retrace interval of the other channel to gate the extended aspect ratio luminance and chrominance information from the other channel so that it can be filtered and properly translated in frequency. The receiver then combines the conventional luminance and chrominance information and the high-frequency luminance and chrominance information with the processed extended aspect ratio luminance and chrominance information for purposes of display. In addition, the extended aspect ratio chrominance information (I e Q e segments) is placed in alternate horizontal retrace intervals. Since the I e and Q e segments are alternately received, the receiver provides a storage mechanism for storing the segment received on a previous interval so that this segment can be reutilized with a present segment during the present horizontal information interval. Advantageously, the extended aspect ratio luminance and chrominance information from a high-resolution TV camera is encoded into the horizontal retrace interval of the other television channel by modulating the luminance and chrominance information before insertion into the horizontal retrace interval. The extended aspect ratio chrominance information comprises I e and Q e segments that are transmitted in alternate horizontal retrace intervals. The conventional chrominance and luminance information is encoded into a conventional television channel. The high-frequency luminance and chrominance information is encoded into the other television channel. The encoded high-frequency chrominance information is alternately transmitted during active horizontal intervals. The novel method is provided for encoding high-definition luminance and chrominance information from a high-definition video camera into conventional luminance and chrominance information communicated in a first TV channel, high-frequency chrominance and luminance information communicated in a second channel, and extended aspect ratio luminance and chrominance information communicated in the horizontal retrace interval of the second TV channel. The steps involve encoding the low-frequency luminance and chrominance information into the first TV channel, encoding the high-frequency luminance and chrominance information into the second TV channel, filtering the extended aspect ratio luminance and chrominance information from the high-definition luminance and chrominance information, gating and encoding the filtered extended aspect ratio luminance and chrominance information into the horizontal retrace interval of the second TV channel, and transmitting the first and second TV channels to TV receivers. At the receivers, the method provides for decoding the first and second channels by the following steps: decoding the low-frequency luminance and chrominance information, decoding the high-frequency luminance and chrominance information, decoding the extended aspect ratio luminance and chrominance information, and combining the decoded low-frequency luminance and chrominance information, the decoded high-frequency luminance and chrominance information, and the decoded extended aspect ratio luminance and chrominance information together for display purposes. Our invention particularly pertains to high-definition signal encoding and decoding method and apparatus illustratively embodied in video signal processing in the TV transmitter, and in TV receivers for high-definition picture display with extended aspect ratio information. BRIEF DESCRIPTION OF THE DRAWING In general, system elements, when first introduced on a figure, are each designated with a number that uses the figure number as the most significant digits of the element number. FIG. 1 shows the amplitude-frequency characteristics of the conventional baseband video signal; FIG. 2 shows the NTSC standard video wave form; FIG. 3 shows the baseband amplitude-frequency characteristics of a wideband video luminance source; FIG. 4 shows a video signal illustratively capable of providing an aspect ratio of 4.76 to 3 with a 63.5 microsecond horizontal interval; FIG. 5 illustrates the center information of FIG. 4 including synchronization and blanking signals; FIG. 6 illustrates the edge information of the video signal illustrated in FIG. 4; FIG. 7 shows the results of high-pass filtering the baseband amplitude-frequency characteristics of FIG. 3; FIG. 8 shows the two sidebands produced by modulating the signal of FIG. 7; FIG. 9 shows the composite baseband amplitude-frequency characteristics including the high-frequency chrominance and luminance information; FIGS. 10 and 11 are a block diagram of the high-definition encoder of our invention; FIG. 12 illustrates the signals generated by timing generator 1066 of FIG. 10; FIGS. 13 and 14 are a block diagram of the high-definition decoder of our invention; and FIGS. 15 and 16 show the manner in which certain of the figures should be arranged to show the specific illustrative embodiment of the invention. GENERAL DESCRIPTION The following describes a TV system that is fully compatible with conventional NTSC TV receivers and also capable of displaying high resolution and extended aspect ratio TV pictures on the system's specially designed receivers. The system uses one TV channel for carrying the conventional TV signal and a second channel for carrying the high-frequency luminance and chrominance information plus the extended aspect ratio information. During the active horizontal line time of the first TV channel, a high-definition signal from a wideband video source is separated into low-frequency and high-frequency signals. The low-frequency signal is encoded and transmitted in the first channel, and the high-frequency signal is encoded and transmitted in the second channel. During the synchronization and retrace interval of the first channel, the high-definition signal is band-limited, encoded, and transmitted in the second channel in order to provide extended aspect ratio information to the specially designed receivers. The latter are responsive to both channels to display high resolution TV pictures with extended aspect ratio information. FIG. 1 shows the nominal baseband amplitude-frequency characteristics of the video signal at the transmitter in the conventional NTSC system. The frequency of the chrominance subcarrier F sc is displaced by the 455th harmonic of half the horizontal line-scanning frequency F H from the origin. This relationship was chosen to take advantage of the fact that the luminance spectra, Y n , is actually not continuous (as shown) but exists as a multiplicity of groups of signals (not shown) centered about the harmonics of the line-scanning frequency F H . The chrominance subcarrier F sc is set at a frequency which is an odd harmonic of half the line-scanning frequency, so as to lie in a valley between two of such signal groups. The chrominance subcarrier F sc is conventionally quadrature amplitude modulated by two chroma signals designated I n and Q n in FIG. 1. The Q n chroma signal reproduces colors from the yellow-green to purple, while the I n chroma signal transmits hues ranging from bluish-green (cyan) to orange. The I n chroma signal contains both double sideband and single sideband portions (it is a vestigial sideband signal). The double sideband portion extends 0.5 megahertz (MHz) on either side of the in-phase chrominance subcarrier. The single sideband portion extends from 0.5 to 1.5 MHz below the in-phase chrominance subcarrier. The narrow band Q n chroma signal is double sideband, extending 0.5 MHz on either side of the quadrature chrominance subcarrier. The normal NTSC video signal uses a 15.7 kilohertz (kHz) scan rate resulting in 63.5 microsecond scan periods. The normal NTSC video signal allots approximately 11 microseconds (referred to as the horizontal retrace interval) in each 63.5 microsecond scan period for synchronization and blanking information resulting in 52.5 microseconds for an active video signal time. This nominal video waveform is illustrated in FIG. 2. With a 15.7 kHz line scan rate and utilizing 52.5 microseconds out of each 63.5 microsecond scan period, the NTSC video signal delivers a 4 to 3 aspect ratio picture to a conventional TV receiver. In FIG. 3, the baseband amplitude-frequency characteristic of a wideband video source having an illustrative luminance bandwidth of 7.5 MHz, adequate to provide a horizontal resolution of 600 lines, is shown. This broadened baseband source is assumed to be provided by improved camera technology which is described in greater detail with respect to FIG. 10 and 11. This improved camera technology produces a video signal, X, as illustrated in FIG. 4 that provides 62.5 microseconds of active time per each horizontal scan line at a 15.7 kHz scan rate. This video signal illustratively provides an aspect ratio of 4.76 to 3 with 1 microsecond being allowed for the active horizontal retrace interval. The format of the X signal represents the format of both the luminance information, Y, and the chrominance information, C (which comprises I and Q signals), from the improved camera. If the horizontal retrace interval can be reduced to 0.1 microsecond, the aspect ratio can be increased to 4.83 to 3, with 4.84 to 3 being the theoretical maximum as the retrace interval goes to zero. The encoder of our system proportions the X signal illustrated in FIG. 4 into a center portion, X c , as illustrated in FIG. 5 and into an edge portion, X e , as illustrated in FIG. 6. When the wideband luminance source signal, Y of FIG. 3, is presented to both a conventional (NTSC) encoder (after gating with the center signal of FIG. 12) and to a high-pass filter, the NTSC encoder accepts the lower 4.2 MHz of the 7.5 MHz luminance signal as shown in FIG. 1, and the high-pass filter, with a cutoff frequency of approximately 3 MHz communicates a luminance output, Y H , as shown in FIG. 7 of approximately 5 MHz. The luminance output Y H is delivered to a balanced modulator, advantageously of the "product" type, having a local oscillator whose frequency is set at 7/2 times the frequency of the chrominance subcarrier F sc embedded in the NTSC portion of FIG. 1. The modulator's output contains the upper and lower sideband signals shown in FIG. 8. The upper sideband of FIG. 8 is suppressed and the lower sideband is added to the conventional NTSC portion to yield the composite baseband amplitude-frequency characteristic (exclusive of the high-frequency chrominance information, C') shown in FIG. 9. As illustrated in FIG. 9 the conventional NTSC chrominance information comprising the normal NTSC chroma information (I n and Q n ) is transmitted in the conventional manner in the lower portion of FIG. 9 which is a conventional television channel. High-frequency chrominance information, C', in the form of the X c signal of FIG. 5 is also transmitted in the Y' portion of the composite baseband amplitude-frequency characteristics shown in FIG. 9. The high-frequency chrominance information, C', which consists of I' and Q' components is in the frequency spectrum between 0.5 MHz to 2 MHz as received from the high-definition TV camera. The I' and Q' signals are communicated in a time multiplexed manner. During any given active time either Q' or I' is transmitted along with the Y' signal (frequency interlaced) of FIG. 9 with the other color component being transmitted in the next active horizontal interval. The edge luminance and chrominance information in the form of the X e signal is transmitted during the 11 microsecond horizontal retrace interval of the second channel (Y' and C') illustrated in FIG. 9. This horizontal retrace interval corresponds in time to the horizontal retrace and synchronization interval of the first channel. This information can be transmitted during the horizontal retrace interval in the second channel since the horizontal sync pulse and color burst information are transmitted in the first channel as part of the standard NTSC signals. To utilize the 10 microseconds of the available 11 microseconds in the horizontal retrace interval of the second channel for transmission of the X e form signals, it is necessary to first band limit the luminance signal, Y, to 5.2 MHz and the chrominance signals, Q and I to 1.5 MHz. These signals, after being band limited, are then modulated in a similar manner in which the Y' and C' signals in the format of the X c signal were modulated before being inserted into the horizontal retrace interval of the second channel. DETAILED DESCRIPTION Referring now to FIG. 10 and 11, a block diagram of an extended aspect ratio high-definition TV encoder is described. The increased bandwidth baseband signal of FIG. 3 is provided by circuit 1000. Circuit 1000 advantageously may be of the type described in the article "Concepts for a Compatible HI-FI Television System" by B. Wendland in NTG-FACHBER, (Germany), Vol. 7, September, 1980, at pp. 407-416. That article describes an improved video source camera 1001 capable of providing an output having more than the conventional number of scanning lines. The circuit 1000 is further improved so as to provide the additional active information in a horizontal scan line as illustrated in FIG. 4. Illustratively, camera 1001 is capable of functioning as a 1050 line source of wideband red, green, and blue (R, G, B) signals. The wideband R, G, B signals from camera 1001 are then subject to the anti-aliasing filtering by circuit 1002 to remove frequency components above the Nyquist rates. Because the scanning process that changes the image into an electrical signal in the camera and then reassembles the image on the picture tube is really a sampling process, the vertical resolution is usually determined by reducing the effective number of scan lines (the total number less the number of lines in the vertical blanking interval) by a "Kell" factor of 0.6 to 0.7. Vertical filtering of the camera/source signal, however, reduces the affects of aliasing and provides a "Kell" factor approaching unity so that a vertical resolution approaching 483 lines, (525 minus (2×21)) is achieved. The point spread function (PSF) of the camera and the display are analogous to the impulse response of a linear system and are usually adjusted by shaping the electronic beam. However, a narrow PSF in the vertical direction means a wide frequency spectrum and aliasing, and a wide PSF means overlapping of adjacent lines and low-pass filtering in the vertical direction (defocusing). In the NTSC system, the PSF is adjusted to compromise between aliasing and defocusing. Anti-aliasing (prefiltering) is employed in circuit 1000 of the encoder apparatus of FIG. 10 and interpolation (postfiltering) is employed at the corresponding circuit 1350 decoder apparatus of the receiver, (FIGS. 13 and 14). In circuit 1000, the anti-alias filtered camera signals are applied by circuit 1002 to scan converter 1003. Scan converter 1003 deletes every second line of each of the 1050 line R, G, B signals to obtain a 525 line signal for ultimate transmission that is compatible with the existing (NTSC) television receivers. The wideband R, G, B signals at the output of the scan converter 1003 are applied to the R, G, B to Y, I, Q conversion matrix 1020. The output of matrix circuit 1020 takes the form of the X signal of FIG. 4. Because of the wideband input of the R, G, B signals, the luminance output Y of conversion matrix 1020 exhibits the wideband amplitude-frequency characteristics of FIG. 3. The selection of the information illustrated in FIGS. 5 and 6 from the output of matrix circuit 1020 is controlled by a center signal and an edge signal that are generated by timing generator 1066. The time relationship of the center and edge signals is illustrated in FIG. 12. When the center signal is at the "1" state, the center information illustrated in FIG. 5 is being transmitted from matrix 1020; and when the edge signal is at the "1" state, the edge information illustrated in FIG. 6 is being transmitted from matrix 1020. When the center signal is in the "1" state, the Y, I, and Q signals from matrix 1020 are processed by the NTSC encoder 1030, the Y signal by subcircuit 1101, the I signal by subcircuit 1102, and the Q signal by subcircuit 1103 to produce the two baseband signals illustrated in FIG. 9 that are transmitted after summation by adder 1071 as two conventional TV channels. Gate 1050 is responsive to the center signal to transmit the Y signal from matrix 1020 to the NTSC encoder 1030 and high-pass filter 1033. Gate 1051 is responsive to the center signal to transmit the I signal from matrix 1020 to NTSC encoder 1030 and adder circuit 1062. Correspondingly, gate circuit 1052 is responsive to the center signal to transfer the Q signal to NTSC encoder 1030 and adder circuit 1065. NTSC encoder 1030 in response to the gated Y, I, and Q signals provides conventional luminance and chrominance output signals, Y n +C n , to adder 1071. In the absence of any other input, the output of adder 1071 would simply be a conventional NTSC baseband signal communicated to the final video modulator stage (not shown) that would radiate a signal to a designated TV channel according to the frequency of the video carrier selected. However, adder 1071 receives additional inputs C', C' e , Y', and Y' e , to be described, and the latter are transmitted by the final modulator stage (not shown) in the second of two designated TV channels. These channels should preferably be adjacent channels to minimize the affects of weather, however, more widely separated channels may also be employed. The high-frequency, gated portion of the Y signal from 1020 is modulated and transmitted to adder 1071 by blocks 1033, 1032, 1061, 1034 and 1053. Oscillator 1031 receives the chrominance subcarrier F sc from encoder 1030 and serves as a local oscillator for modulator 1032. The frequency of the local oscillator's output is advantageously chosen to be 7/2 the frequency of the chrominance subcarrier F sc . In the NTSC system, where the baseband chrominance subcarrier is 455×F H /2, the local oscillator frequency, F c , provided by oscillator 1031 to modulator 1032 is approximately 12.53 MHz. The other signal that is received by modulator 1032 is the upper portion of the wideband luminance signal, Y H , which is received from the output of gate 1050 during the active time of the center signal. The output of gate 1050 is first filtered by high-pass filter 1033. Filter 1033 is advantageously chosen to have a crossover frequency of approximately 3 MHz. In response to these two inputs, the output of modulator 1032 contains the two sideband signals shown in FIG. 8. The upper sideband signal is suppressed by bandpass filter 1034, and the lower sideband signal of Y' is communicated to adder 1071. Before the Y' signal is communicated to filter 1034, it must be communicated through gate circuit 1053 and summation circuit 1061. The purpose of summation circuit 1061 is to allow the luminance signal to consist of either Y' or Y e depending upon whether the center or edge signal is presently active. The center signal controls gate 1053 to gate the Y' signal to summation circuit 1061 at the proper time, and summation circuit 1061 then communicates the signal to filter 1034. The latter suppresses the upper sideband signal and communicates the lower sideband signal to adder 1071. During the center time, adder 1071 combines signals Y n and C n from NTSC encoder 1030 with the wideband luminance signal Y' from filter 1034 to yield a baseband output signal having the baseband amplitude-frequency characteristics (with the exception of C') of FIG. 9. This baseband amplitude-frequency characteristic is capable of providing a high definition image within a signal spectrum requiring not more than two conventional (6 MHz) video channels. The definition of the high-frequency chrominance components of the video signal during the center time is also enhanced in the following manner. The gated I and Q signals from matrix 1020 are delivered via summation circuits 1062 and 1065 to filters 1043 and 1044, respectively, which limit each chrominance component to a 1.5 MHz bandwidth extending from 0.5 to 2.0 MHz. These signals are delivered to bandpass filters 1043 and 1044 during the center time by gates 1051 and 1052 responding to the I and Q signals, respectively, from matrix 1020 and gating the signals to summation circuits 1062 and 1065. The band limited outputs of filter 1043 and 1044 are alternately gated at half the normal line rate (F H /2) by color multiplexor 1070 under control of the line selection circuit 1085. Line selection circuit 1085 receives the composite sync signal from NTSC encoder 1030 and controls multiplexor 1070, by counting the sync pulses, so that each new field starts its first line from the I signal output of filter 1043. The chrominance components I and Q are alternately selected by multiplexor 1070 and are applied to product modulator 1045. The frequency of local oscillator 1047 F o , that is applied to the product modulator 1045 is chosen so that the chrominance output spectra of the modulator interleave, without interference, with the high-frequency luminance spectra of the signals from band-pass filter 1034. Since multiplexor 1070 samples the chrominance components at half the horizontal line rate, the multiplexor's output spectra is naturally grouped at multiples of half the line rate. To avoid this interference with the high-frequency luminance spectra, the local oscillator frequency, F o , as applied to the product modulator 1045 is proportioned according to the formula F o =288 F H which is approximately 4.53 MHz. The high-frequency multiplex chrominance components at the output of modulator 1045 are applied to band-pass filter 1046 to eliminate the upper sideband. The upper sideband output, C', of filter 1046 is applied to one input of adder 1071. Since the other inputs of adder 1071 during the center time period are the conventional NTSC baseband signal and the high-frequency luminance signal, Y', the output of adder 1071 provides the composite baseband signal of FIG. 9 including C'. The edge luminance and chrominance information from matrix 1020 is inserted into the second television channel during the horizontal retrace interval in the following manner. The luminance information, Y, from matrix 1020 is received by low-pass filter 1068 that limits the bandwidth to 5.2 MHz. During the edge time, gate 1054 is responsive to the edge signal from timing generator 1066 to communicate the band limited Y signal from filter 1068 to product modulator 1161. Modulator 1161 translates the band limited Y signal into the proper frequency range of the second channel. The other input to modulator 1161 is a 10.1 MHz signal (a multiple of F H ) from oscillator 1060. The output of modulator 1161 is a double sideband suppressed carrier signal which is communicated to band-pass filter 1034 by summation circuit 1061. The upper sideband is eliminated or made into a vestigal sideband signal by band-pass filter 1034 resulting in the Y' e signal that is communicated by band-pass filter 1034 to adder 1071. The Y' e signal occupies the same position in the spectrum during the horizontal retrace interval as is occupied by the Y' signal during the center time. During each horizontal scan period, Y' is present during the center time (duration of 52.5 microseconds) and the Y' e signal is present during the edge time (duration of 10 microseconds). The chrominance edge information is communicated to the television receiver in the following manner. The I and Q signal from matrix 1020 are first communicated to low-pass filters 1042 and 1041, respectively, in order to band limit the I and the Q signals. The gates 1055 and 1056 produce the band limited chroma signals during only the edge time. These two signals are translated in frequency by modulating with a 2 MHz carrier (a multiple of F H )to produce two double sideband signals that are then passed through 0.5 to 2.0 MHz band-pass filters to suppress the upper sideband signals. The two resulting signals are then alternately selected by multiplexor 1070 and modulated and filtered by circuits 1045 and 1046, respectively, as was previously described for the I' and Q' signals. Describing this process now in greater detail, the output of low-pass filter 1042 is gated to modulator 1063 during the edge time by gate 1055 responding to the edge signal from timing generator 1066. Modulator 1063 is responsive to the I signal to output a double sideband signal to adder 1062 which transfers it and the center gated I signal to band-pass filter 1043. Filter 1043 suppresses the upper sideband of the signal and makes a resulting single sideband representation of the I e signal available to multiplexor 1070. Blocks 1041, 1056, 1064, 1048, 1065 and 1044 process the Q signal in the same manner as previously described for the I signal to produce a similar Q e edge signal. Multiplexor 1070 responds to these signals in the identical manner as previously described for the I' and Q' signals to produce a C e signal during the edge time which alternately contains the I e or Q e signals. Modulator 1045 is responsive to the output of multiplexor 1070 to produce C' e that alternately contains I' and Q' e . Adder 1071 is continuously responsive to the Y', Y' e , C', C' e , Y n and C n signals to produce the Z signal as illustrated in FIG. 9 (with Y' e and C' e added to Y' and C', respectively) which is then modulated and transmitted over conventional video channels. A decoder for receiving the signal shown in FIG. 9 is illustrated in FIG. 13. Radio frequency (RF) tuner, video detector, and intermediate frequency (IF) stage 1301 receives the incoming TV signal, i.e., the two TV channels containing the broadband luminance and chrominance information heretofore described. Accordingly, stage 1301 may contain either a broadband RF tuner capable of receiving two adjacent TV channels or separate RF tuners each tuned to a respective channel. In either event, the output of stage 1301 provides the baseband amplitude-frequency characteristic of FIG. 9 with Y' e and C' e added to Y' and C', respectively. Stage 1301 is coupled at its output to circuits 1360, 1340, 1302, 1312, and 1361. The low-frequency luminance information, Y L , is recovered by low-pass filter 1360 whose output is communicated to sum circuit 1374. The high-frequency luminance signal, Y H , is recovered by blocks 1340, 1366, 1341, and 1331 during the center time. The Y H and Y L signals are combined by sum circuit 1374 and the result is gated to sum circuit 1372 at the center time by gate 1375 in response to the center signal from block 1303. The Y' signal is recovered from the output of stage 1301 by band-pass filter 1340 limiting the Y signal to a region from 4.9 to 10.1 MHz and comb filter 1366 removing the C' signal. Modulator 1341 and filter 1331 are responsive to the output of comb filter 1366 to deliver a lower sideband signal, 2.5 to 7.5 MHz, containing the Y' information. Modulator 1341 receives a local oscillator input from oscillator 1367 that is 7/2 times the frequency of the color subcarrier F sc as detected by the NTSC decoder 1302. The other input to modulator 1341 is the upper portion of the baseband video signal (Y) in the center of the image extending from approximately 4.9 to 10.1 MHz as shown in FIG. 9 as Y' and separated by band-pass filter 1340 and comb filter 1366. The output of filter 1331 contains the translated Y H signal and is communicated to sum circuit 1374. Gate 1375 communicates the Y L and the translated Y H to sum circuit 1372 only during the center time in response to the center signal from frequency synthesizer 1303. The luminance information contained in the edge luminance signal, Y' e , is recovered from the output of stage 1301 by the blocks 1340, 1366, 1368, and 1370. Filters 1340 and 1366 filter the Y' e signal received from stage 1301 in the same manner as was previously described for the Y' signal. The Y' e signal is then translated down to baseband frequency by modulator 1368 that multiplies the Y' e signal with a carrier at approximately 10.1 MHz that is derived by oscillator 1369. Low-pass filter 1370 retains only the baseband portion of the output of modulator 1368. The output of low-pass filter 1370, which is Y e , is gated at the edge time to sum circuit 1372 by gate 1371 in response to the edge signal. The output of sum circuit 1372 is the combination of Y L plus the translated Y H during the center time and the Y e signal during the edge time so that adder 1307 is constantly receiving a luminance signal (Y) from sum circuit 1372. The chrominance information is recovered from the output of stage 1301 in the following manner. NTSC decoder 1302 receives the broadband signal of FIG. 9 with Y' e and C' e included from stage 1301 and at its output provides the low frequency Q n and I n , chrominance signals (band limited to 0.5 MHz) designated Q L and I L , to adders 1304 and 1305, respectively. Adders 1304 and 1305 combine the Q L and I L signals with high frequency chrominance signals (Q H and I H translated and center gated) and edge chrominance signals (Q e and I e translated and edge gated) that are recovered from the output of stage 1301 by subcircuit 1320. Subcircuit 1320 demodulates the high frequency chrominance signals, I' and Q' from the output of 1301 in the following manner. The I' and Q' signals are being transmitted on alternate horizontal lines in the upper 6 MHz band by a distant television transmitter. Band-pass filter 1361 is responsive to the output of stage 1301 to limit the signals to the region of 5.0 to 6.5 MHz in which the high frequency and edge chrominance signals are transmitted as shown in the baseband signal of FIG. 9. The comb filter 1362 removes the Y' and Y' e signals before transmitting the chrominance information to modulator 1363. Modulator 1363 provides a frequency translation function by modulating the chrominance information into the proper chrominance band of 0.5 to 2.0 MHz. The modulator also translates the chrominance information up to the 2F o range but this is removed by filter 1365. The output of filter 1365 is the C H signal which alternately comprises I H and Q H signals. Since the I' and Q' signals are being alternately transmitted, it is necessary to store one signal from a previous line and reuse it on the present line in order to obtain the desired information. Delay line circuit 1386 performs this storage function. Multiplexor 1373 is responsive to the output of frequency synthesizer 1303 to alternate between the output of bandpass filter 1365 and delay line 1386 so that the information for the Q H and I H signals is continuous from multiplexor 1373. The translated Q H and I H signals from multiplexor 1373 are communicated by gates 1387 and 1388 in response to the center signal from frequency synthesizer 1303 during the center time to sum circuits 1398 and 1399, respectively. During the center time, sum circuits 1398 and 1399 communicate the translated and gated Q H and I H signals to adders 1304 and 1305, respectively. The Q L signal and the translated and gated Q H signal are combined by adder 1304, similarly the I L signal and the translated and gated I H signal are combined by adder 1305 before transmission to matrix circuit 1306. The edge chrominance information is handled in a similar manner as the chrominance high-frequency information by subcircuit 1320 with the following exception. The chrominance edge information occupies a bandwidth of 0 to 1.5 MHz and in order to recover this information from the output of multiplexor 1373, it is necessary to frequency translate the outputs of multiplexor 1373 by 2 MHz. The modulators 1390 and 1393 generate both the baseband edge signals and components translated up by 4 MHz. The upper portion of these signals are then eliminated by low-pass filters leaving only the baseband signals that occupy the region from 0 to 1.5 MHz and contain the edge chrominance information. These operations are performed by blocks 1390 through 1395. The resulting outputs of low-pass filters 1392 and 1395 contain the baseband versions of I e and Q e , respectively, and only need to be gated with the edge signal controlling gates 1396 and 1397, respectively, to produce the desired edge chrominance information. The translated and gate Q e signal is communicated by gate 1396 to sum circuit 1398 and the translated and gated Q H signal is communicated by gate 1387 to sum circuit 1398 at the appropriate times. Sum circuit 1398 combines the translated and gated Q e and Q H signals before transmission to adder 1304. Similarly, the translated and gated I H and I e signals are combined by sum circuit 1399 before transmission to adder circuit 1305. The translated Q H and I H signals are transmitted during the center time to adders 1304 and 1305, respectively, while the translated Q e and I e signals are transmitted during the edge time to adders 1304 and 1305, respectively. In turn, adders 1304 and 1305 communicate the I and Q signals to matrix circuit 1306. Matrix circuit 1306 combines the I and Q signals outputted by adders 1305 and 1304, respectively, to produce the R-Y, G-Y, B-Y, signals that are transmitted to adder 1306. Adder 1307, in response to the outputs of adder 1372 and the matrix circuit 1306, produces the R, G, and B signals that are then used to display the video picture by subcircuit 1350. While the illustrative embodiments of our invention have been described specifically with relation to NTSC standards and protocols, it is to be understood that the principles of our invention are applicable to other standards and protocols, such as PAL. Furthermore, these circuits and amplitude-characteristics which have been described are deemed to be illustrative of the principles of our invention. Numerous modifications may be made by those skilled in the art without departing from the spirit and scope of our invention.

A television system having a fully compatible high-definition signal with extended aspect ratio information receivable at conventional resolution by conventional TV receivers without auxiliary apparatus with one TV channel carrying the conventional TV signal while high-frequency luminance and chrominance information plus extended aspect ratio information are provided in a second TV channel. The extended aspect ratio information including luminance and chrominance information is transmitted during the horizontal retrace interval of the second TV channel. The extended aspect ratio chrominance information comprises I e and Q e segments which are transmitted during alternate horizontal retrace intervals. Since the segments are alternately transmitted, a storage mechanism is provided so that a segment received during a previous horizontal retrace interval can be reused during the present horizontal retrace interval for displaying the complete chrominance edge information.

BACKGROUND [0001] Technical Field [0002] This present disclosure generally relates to electronic commerce software applications and, more particularly, to evaluating prices and transactions for purchasing. [0003] Description of the Related Art [0004] Commodity items such as lumber, agricultural products, metals, and livestock/meat are usually traded in the open market between a number of buyers and sellers. The sales transactions of most commodity items involve a number of parameters. For instance, in the trade of commodity lumber, a buyer usually orders materials by specifying parameters such as lumber species, grade, size (i.e., 2×4, 2×10, etc.), and length, as well as the “tally” or mix of units of various lengths within the shipment, method of transportation (i.e., rail or truck), shipping terms (i.e., FOB or delivered), and desired date of receipt, with each parameter influencing the value of the commodity purchase. Given the multiple possible combinations of factors, a commodity buyer often finds it difficult to objectively compare similar but unequal offerings among competing vendors. [0005] For example, in a case where a lumber buyer desires to order a railcar load of spruce (SPF) 2×4's of #2 & Better grade, the buyer would query vendors offering matching species and grade carloads seeking the best match for the buyer's need or tally preference at the lowest market price. Lumber carloads are quoted at a price per thousand board feet for all material on the railcar. When the quoted parameters are not identical, it is very difficult for buyers to determine the comparative value of unequal offerings. [0006] Typically, a lumber buyer will find multiple vendors each having different offerings available. For example, a railcar of SPF 2×4's may be quoted at a rate of $300/MBF (thousand board feet) by multiple vendors. Even though the MBF price is equal, one vendor's carload may represent significantly greater marketplace value because it contains the more desirable lengths of 2×4's, such as market-preferred 16-foot 2×4's. When the offering price varies in addition to the mix of lengths, it becomes increasingly difficult to compare quotes from various vendors. Further, because construction projects often require long lead times, the lumber product may need to be priced now, but not delivered until a time in the future. Alternately, another species of lumber (i.e., southern pine) may represent an acceptable substitute. [0007] Therefore, from the foregoing, there is a need for a method and system that allows buyers to evaluate the price of commodity offerings possessing varying shipping parameters. BRIEF SUMMARY [0008] The present disclosure describes a system that operates in a networked environment. The system comprises at least one server that includes a network interface, a non-transitory computer-readable medium, and a processor in communication with the network interface and the computer-readable medium. The computer-readable medium has computer-executable instructions stored thereon that, when executed, implement components including at least a metric server adapter and a metrics application. The processor is configured to execute the computer-executable instructions stored in the computer-readable medium. [0009] In various embodiments, the metric server adapter includes governing logic programmed to manage at least one evaluation service and a plurality of predefined instructions that pertain to the evaluation service and/or data used to provide the at least one evaluation service. The metrics application includes one or more production applications or modules programmed to manage one or more purchase and/or analysis processes, to execute the evaluation service in coordination with the metric server adapter. The metrics application also manages one or more user interfaces that, in operation, facilitate interactions with the server. [0010] In operation, the server is configured to receive a plurality of price data sets from at least one computing device in communication with the server, or retrieve a plurality of price data sets from at least one data source accessible to the server. Each price data set comprises an offer to buy or sell that identifies price data for at least one item possessing a plurality of attributes that include two or more parameter values or a plurality of items having attributes that differ by at least one parameter value. At least one price data set represents an unequal offer in that the price data set identifies at least one item that differs by at least one parameter value from the item as identified in another price data set. [0011] In response to receipt or retrieval of at least one price data set, the server implements the evaluation service which causes the metrics application, for each price data set, to obtain time-dependent metric data from at least one data source accessible to the server. The obtained metric data includes market reference price data for one or more responsive items possessing attributes that are responsive to attributes of a respective item identified in the price data set. Each responsive item in the metric data possesses a plurality of attributes that include at least one parameter value. [0012] The metrics application evaluates the plurality of attributes of each responsive item in the metric data relative to the attributes for the respective item identified in the price data set to dynamically discover relationships within the attributes. Discovery of a relationship comprising a difference is disclosed to the metric server adapter which enables the metric server adapter to define offer-specific instructions for adapting the metric data for the respective item. [0013] The metrics application normalizes the metric data by executing the offer-specific instructions for adapting the metric data for the respective item. Execution of at least one offer-specific instruction causes one or more adjustment values to be generated and applied to the market reference price data for at least one responsive item that differs by at least one parameter value from the respective item as identified in the price data set, transforming the market reference price data for the at least one responsive item and automatically producing one or more offer-specific market reference price data values for the respective item. [0014] The metrics application generates at least one comparative metric that pertains to the at least one evaluation service. The comparative metric is based, at least in part, on one or a combination of the offer-specific market reference price data values produced for the respective item or items identified in a price data set. The comparative metric comprises a differential ratio or index value that compares the price data identified for the item or items in the offer with the offer-specific market reference price data values produced for the item or items. [0015] Also disclosed herein, in various embodiments, is a method for evaluating unequal offers in a networked environment. The method includes receiving, at at least one server, a plurality of price data sets. The server operates under control of computer-executable instructions that, when executed by a processor, implement components including at least a governing logic component and a production component. Each price data set comprises an offer to buy or sell that identifies price data for at least one item possessing attributes that include two or more parameter values or a plurality of items having attributes that differ by at least one parameter value. At least one price data set represents an unequal offer in that the price data set identifies at least one item that differs by at least one parameter value from the item as identified in another price data set. [0016] For each received price data set, the method further comprises implementing, by the server, at least one evaluation service. In operation, the evaluation service includes obtaining, by the production component, time-dependent market-reference data from at least one data source accessible to the server. The market reference data includes market-reference price data for one or more responsive items possessing attributes that are responsive to attributes of a respective item identified in the price data set, wherein each responsive item possesses a plurality of attributes including at least one parameter value. [0017] The evaluation service further includes evaluating, by the production component, the plurality of attributes of each responsive item in the market reference data relative to the plurality of attributes for the respective item as identified in the price data set to dynamically discover relationships within the attributes. Discovery of a relationship comprising a difference is disclosed to the governing logic component which enables the governing logic component to define offer-specific instructions for adapting the market reference data for the respective item. [0018] The market reference data is normalized, wherein the production component executes the offer-specific instructions for adapting the market reference data for the respective item. Execution of at least one offer-specific instruction causes one or more adjustment values to be generated and applied to the market reference price data for at least one responsive item that differs by at least one parameter value from the respective item as identified in the price data set, transforming the market reference price data for the at least one responsive item and automatically producing one or more offer-specific market reference price data values for the respective item. [0019] At least one comparative metric that pertains to the evaluation service is generated by the production component. The comparative metric is based, at least in part, on one or a combination of the offer-specific market reference price data values produced for the respective item or items identified in the price data set. The comparative metric comprises a differential ratio or index value that compares the price data identified for the item or items in the offer with the offer-specific market reference price data values produced for the item or items. [0020] Further disclosed herein is a non-transitory computer-readable medium having computer-executable instructions stored thereon. The computer-executable instructions, when executed, cause at least one server in a networked environment to perform operations that include receiving, at the server, a plurality of price data sets. The server operates under control of the computer-executable instructions that, when executed by a processor, implement components including a governing logic component and a production component. [0021] Each price data set includes price data and represents an offer to buy or sell at least one identified item possessing attributes that include two or more parameter values or a plurality of items having attributes that differ by at least one parameter value. At least one price data set represents an unequal offer in that the price data set identifies at least one item that differs by at least one parameter value from the item as identified in another price data set. [0022] Implementing at least one evaluation service, for each received price data set, the computer-executable instructions cause the server to obtain, by the production component, time-dependent market-reference data from at least one data source accessible to the server. The market reference data includes market-reference price data for one or more responsive items possessing attributes that are responsive to attributes of a respective item identified in the price data set. Each responsive item in the market-reference data possesses a plurality of attributes including at least one parameter value. [0023] The production component evaluates the plurality of attributes of each responsive item in the market reference data relative to the plurality of attributes for the respective item as identified in the price data set to dynamically discover relationships within the attributes. Discovery of a relationship comprising a difference is disclosed to the governing logic component which enables the governing logic component to define offer-specific instructions for adapting the market reference data for the respective item. [0024] The production component normalizes the market reference data, wherein the production component executes the offer-specific instructions for adapting the market reference data for the respective item. Execution of at least one offer-specific instruction causes one or more adjustment values to be generated and applied to the market reference price data for at least one responsive item that differs by at least one parameter value from the respective item as identified in the price data set, transforming the market reference price data for the at least one responsive item and automatically producing one or more offer-specific market reference price data values for the respective item. [0025] The production component generates at least one comparative metric that pertains to the at least one evaluation service. The comparative metric is based, at least in part, on one or a combination of the offer-specific market reference price data values produced for the respective item or items identified in the price data set. The comparative metric comprises a differential ratio or index value that compares the price data identified for the item or items in the offer with the offer-specific market reference price data values produced for the item or items. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0026] The foregoing aspects and many of the attendant advantages of the present disclosure will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: [0027] FIG. 1 is a block diagram of a prior art representative portion of the Internet; [0028] FIG. 2 is a pictorial diagram of a system of devices connected to the Internet, which depict the travel route of data; [0029] FIG. 3 is a block diagram of the several components of the buyer's computer shown in FIG. 2 that is used to request information on a particular route; [0030] FIG. 4 is a block diagram of the several components of an information server shown in FIG. 2 that is used to supply information on a particular route; [0031] FIG. 5 is a flow diagram illustrating the logic of a routine used by the information server to receive and process the buyer's actions; [0032] FIGS. 6A-6B are flow diagrams illustrating another embodiment of the logic used by the information server to receive and process the quotes and quote requests of both buyers and vendors; [0033] FIG. 7 is a flow diagram illustrating another embodiment of the logic used by the information server to execute the process of a catalog purchase; [0034] FIGS. 8A-8D are images of windows produced by a Web browser application installed on a client computer accessing a server illustrating one embodiment of the present disclosure; and [0035] FIG. 9 is a flow diagram illustrating one embodiment of the normalization process described herein. DETAILED DESCRIPTION [0036] The term “Internet” refers to the collection of networks and routers that use the Internet Protocol (IP) to communicate with one another. A representative section of the Internet 100 as known in the prior art is shown in FIG. 1 in which a plurality of local area networks (LANs) 120 and a wide area network (WAN) 110 are interconnected by routers 125 . The routers 125 are generally special-purpose computers used to interface one LAN or WAN to another. Communication links within the LANs may be twisted wire pair, or coaxial cable, while communication links between networks may utilize 56 Kbps analog telephone lines, or 1 Mbps digital T-1 lines, and/or 45 Mbps T-3 lines. Further, computers and other related electronic devices can be remotely connected to either the LANs 120 or the WAN 110 via a modem and temporary telephone link. Such computers and electronic devices 130 are shown in FIG. 1 as connected to one of the LANs 120 via dotted lines. It will be appreciated that the Internet comprises a vast number of such interconnected networks, computers, and routers and that only a small representative section of the Internet 100 is shown in FIG. 1 . [0037] The World Wide Web (WWW), on the other hand, is a vast collection of interconnected, electronically stored information located on servers connected throughout the Internet 100 . Many companies are now providing services and access to their content over the Internet 100 using the WWW. In accordance with the present disclosure, and as shown in FIG. 2 , there may be a plurality of buyers operating a plurality of client computing devices 235 . FIG. 2 generally shows a system 200 of computers and devices to which an information server 230 is connected and to which the buyers' computers 235 are also connected. Also connected to the Internet 100 is a plurality of computing devices 250 associated with a plurality of sellers. The system 200 also includes a communications program, referred to as CEA, which is used on the sellers' computing devices 250 to create a communication means between the sellers' backend office software and the server applications. [0038] The buyers of a market commodity may, through their computers 235 , request information about a plurality of items or order over the Internet 100 via a Web browser installed on the buyers' computers. Responsive to such requests, the information server 230 , also referred to as a server 230 , may combine the first buyer's information with information from other buyers on other computing devices 235 . The server 230 then transmits the combined buyer data to the respective computing devices 250 associated with the plurality of sellers. Details of this process are described in more detail below in association with FIGS. 5-7 . [0039] Those of ordinary skill in the art will appreciate that in other embodiments of the present disclosure, the capabilities of the server 230 and/or the client computing devices 235 and 250 may all be embodied in the other configurations. Consequently, it would be appreciated that in these embodiments, the server 230 could be located on any computing device associated with the buyers' or sellers' computing devices. Additionally, those of ordinary skill in the art will recognize that while only four buyer computing devices 235 , four seller computing devices 250 , and one server 230 are depicted in FIG. 2 , numerous configurations involving a vast number of buyer and seller computing devices and a plurality of servers 230 , equipped with the hardware and software components described below, may be connected to the Internet 100 . [0040] FIG. 3 depicts several of the key components of the buyer's client computing device 235 . As known in the art, client computing devices 235 are also referred to as “clients” or “devices,” and client computing devices 235 also include other devices such as palm computing devices, cellular telephones, or other like forms of electronics. A client computing device can also be the same computing device as the server 230 . An “agent” can be a person, server, or a client computing device 235 having software configured to assist the buyer in making purchasing decisions based on one or more buyer-determined parameters. Those of ordinary skill in the art will appreciate that the buyer's computer 235 in actual practice will include many more components than those shown in FIG. 3 . However, it is not necessary that all of these generally conventional components be shown in order to disclose an illustrative embodiment for practicing the present invention. As shown in FIG. 3 , the buyer's computer includes a network interface 315 for connecting to the Internet 100 . Those of ordinary skill in the art will appreciate that the network interface 315 includes the necessary circuitry for such a connection and is also constructed for use with TCP/IP protocol. [0041] The buyer's computer 235 also includes a processing unit 305 , a display 310 , and a memory 300 , all interconnected along with the network interface 315 via a bus 360 . The memory 300 generally comprises a random access memory (RAM), a read-only memory (ROM), and a permanent mass storage device, such as a disk drive. The memory 300 stores the program code necessary for requesting and/or depicting a desired route over the Internet 100 in accordance with the present disclosure. More specifically, the memory 300 stores a Web browser 330 , such as Netscape's NAVIGATOR® or Microsoft's INTERNET EXPLORER® browsers, used in accordance with the present disclosure for depicting a desired route over the Internet 100 . In addition, memory 300 also stores an operating system 320 and a communications application 325 . It will be appreciated that these software components may be stored on a computer-readable medium and loaded into memory 300 of the buyers' computer 235 using a drive mechanism associated with the computer-readable medium, such as a floppy, tape, or CD-ROM drive. [0042] As will be described in more detail below, the user interface which allows products to be ordered by the buyers are supplied by a remote server, i.e., the information server 230 located elsewhere on the Internet, as illustrated in FIG. 2 . FIG. 4 depicts several of the key components of the information server 230 . Those of ordinary skill in the art will appreciate that the information server 230 includes many more components than shown in FIG. 4 . However, it is not necessary that all of these generally conventional components be shown in order to disclose an illustrative embodiment for practicing the present invention. As shown in FIG. 4 , the information server 230 is connected to the Internet 100 via a network interface 410 . Those of ordinary skill in the art will appreciate that the network interface 410 includes the necessary circuitry for connecting the information server 230 to the Internet 100 , and is constructed for use with TCP/IP protocol. [0043] The information server 230 also includes a processing unit 415 , a display 440 , and a mass memory 450 , all interconnected along with the network interface 410 via a bus 460 . The mass memory 450 generally comprises a random access memory (RAM), read-only memory (ROM), and a permanent mass storage device, such as a hard disk drive, tape drive, optical drive, floppy disk drive, or combination thereof. The mass memory 450 stores the program code and data necessary for incident and route analysis as well as supplying the results of that analysis to consumers in accordance with the present disclosure. More specifically, the mass memory 450 stores a metrics application 425 formed in accordance with the present disclosure for managing the purchase forums of commodities products, and a metric server adapter 435 for managing metric data. In addition, mass memory 450 stores a database 445 of buyer information continuously logged by the information server 230 for statistical market analysis. It will be appreciated by those of ordinary skill in the art that the database 445 of product and buyer information may also be stored on other servers or storage devices connected to either the information server 230 or the Internet 100 . Finally, mass memory 450 stores Web server software 430 for handling requests for stored information received via the Internet 100 and the WWW, and an operating system 420 . It will be appreciated that the aforementioned software components may be stored on a computer-readable medium and loaded into mass memory 450 of the information server 230 using a drive mechanism associated with the computer-readable medium, such as floppy, tape, or CD-ROM drive. In addition, the data stored in the mass memory 450 and other memory can be “exposed” to other computers or persons for purposes of communicating data. Thus, “exposing” data from a computing device could mean transmitting data to another device or person, transferring XML data packets, transferring data within the same computer, or other like forms of data communications. [0044] In accordance with one embodiment of the present disclosure, FIG. 5 is a flow chart illustrating the logic implemented for the creation of a Request for Quote (RFQ) by a singular buyer or a pool of buyers. In process of FIG. 5 , also referred to as the pooling process 500 , a buyer or a pool of buyers generate an RFQ which is displayed or transmitted to a plurality of sellers. Responsive to receiving the RFQ, the sellers then send quotes to the buyers. [0045] In summary, the creation of the RFQ consists of at least one buyer initially entering general user identification information to initiate the process. The buyer would then define a Line Item on a Web page displaying an RFQ form. The Line Item is defined per industry specification and units of product are grouped as a “tally” per industry practice. The pooling process 500 allows buyers to combine RFQ Line Items with other buyers with like needs. In one embodiment, the pool buy feature is created by a graphical user interface where the RFQ Line Items from a plurality of buyers are displayed on a Web page to one of the pool buyers, referred to as the pool administrator. The server 230 also provides a Web-based feature allowing the pool administrator to selectively add each RFQ Line Item to one combined RFQ. The combined RFQ is then sent to at least one vendor or seller. This feature provides a forum for pooling the orders of many buyers, which allows individual entities or divisions of larger companies to advantageously bid for larger orders, thus providing them with more bidding power and the possibility of gaining a lower price. [0046] The pooling process 500 begins in step 501 where a buyer initiates the process by providing buyer purchase data. In step 501 , the buyer accesses a Web page transmitted from the server 230 configured to receive the buyer purchase data, also referred to as the product specification data set or the Line Item data. One exemplary Web page for the logic of step 501 is depicted in FIG. 8A . As shown in FIG. 8A , the buyer enters the Line Item data specifications in the fields of the Web page. The Line Item data consists of lumber species and grade 803 , number of pieces per unit 804 , quantities of the various units comprising the preferred assortment in the tally 805 A-E, delivery method 806 , delivery date 807 , delivery location 808 , and the overall quantity 809 . In one embodiment, the buyer must define the delivery date as either contemporaneous “on-or-before” delivery date or specify a delivery date in the future for a “Forward Price” RFQ. In addition, the buyer selects a metric or multiple metrics in a field 810 per RFQ Line Item (tally). As described in more detail below, the metric provides pricing data that is used as a reference point for the buyer to compare the various quotes returned from the sellers. The buyer RFQ Line Item data is then stored in the memory of the server 230 . [0047] Returning to FIG. 5 , at a next step 503 , the server 230 determines if the buyer is going to participate in a pool buy. In the process of decision block 503 , the server 230 provides an option in a Web page that allows the buyer to post their Line Item data to a vendor or post their Line Item data to a buyer pool. The window illustrated in FIG. 8A is one exemplary Web page illustrating these options for a buyer. As shown in FIG. 8A , the links “Post Buyer Pool” 812 and “Post to Vendors” 814 are provided on the RFQ Web page. [0048] At step 503 , if the buyer does not elect to participate in a pool buy, the process continues to step 513 where the server 230 generates a request for a quote (RFQ) from the buyer's Line Item data. A detailed description of how the server 230 generates a request for a quote (RFQ) is summarized below and referred to as the purchase order process 600 A depicted in FIG. 6A . [0049] Alternatively, at decision block 503 , if the buyer elects to participate in a pool buy, the process continues to step 505 where the system notifies other buyers logged into the server 230 that an RFQ is available in a pool, allowing other buyers to add additional Line Items (tallies) to the RFQ. In this part of the process, the Line Items from each buyer are received by and stored in the server memory. The Line Items provided by each buyer in the pool are received by the server 230 using the same process as described above with reference to block 501 and the Web page of FIG. 8A . All of the Line Items stored on the server 230 are then displayed to a pool administrator via a Web page or an e-mail message. In one embodiment, the pool administrator is one of the buyers in a pool where the pool administrator has the capability to select all of the Line Item data to generate a combined RFQ. The server 230 provides the pool administrator with this capability by the use of any Web-based communicative device, such as e-mail or HTML forms. As part of the process, as shown in steps 507 and 509 , the pool may be left open for a predetermined period of time to allow additional buyers to add purchase data to the current RFQ. [0050] At decision block 509 , the server 230 determines if the pool administrator has closed the pool. The logic of this step 509 is executed when the server 230 receives the combined RFQ data from the pool administrator. The pool administrator can send the combined RFQ data to the server 230 via an HTML form or by other electronic messaging means such as e-mail or URL strings. Once the server 230 has determined that the pool is closed, the process continues to block 510 where the Line Items from each buyer (the combined RFQ) are sent to all of the buyers in the pool. The process then continues to step 513 where the server 230 sends the combined RFQ to the vendors or sellers. [0051] Referring now to FIG. 6A , one embodiment of the purchase-negotiation process 600 is disclosed. The purchase-negotiation process 600 is also referred to as a solicited offer process or the market purchase process. In summary, the purchase-negotiation process 600 allows at least one buyer to submit an RFQ and then view quotes from a plurality of vendors and purchase items from selected vendor(s). The logic of FIG. 6A provides buyers with a forum that automatically manages, collects, and normalizes the price of desired commodity items. The purchase-negotiation process 600 calculates a normalized price data set that is based on a predefined metric(s). The calculation of the normalized price data set in combination with the format of the Web pages described herein create an integrated forum where quotes for a plurality of inherently dissimilar products can be easily obtained and compared. [0052] The purchase-negotiation process 600 begins at step 601 where the RFQ, as generated by one buyer or a pool of buyers in the process depicted in FIG. 5 , is sent to a plurality of computing devices 250 associated with a plurality of sellers or vendors. The vendors receive the RFQ via a Web page transmitted by the server 230 . In one embodiment, the vendors receive an e-mail message having a hypertext link to the RFQ Web page to provide notice to the vendor. Responsive to the information in the buyers' RFQ, the process then continues to step 603 where at least one vendor sends their quote information to the server 230 . [0053] In the process of step 603 , the vendors respond to the RFQ by sending their price quote to the server 230 for display via a Web page to the buyer or buyer pool. Generally described, the vendors send an HTML form or an e-mail message with a price and description of the order. The description of the order in the quote message contains the same order information as the RFQ. [0054] FIG. 8B illustrates one exemplary Web page of a vendor quote that is displayed to the buyer. As shown in FIG. 8B , the vendor quote includes the vendor's price 813 , the lumber species and grade 803 , number of pieces per unit 804 , quantities of the various units comprising the preferred assortment in the tally 805 A-E, delivery method 806 , delivery date 807 , and delivery location 808 . In the quote response message, the vendor has the capability to modify any of the information that was submitted in the RFQ. For example, the vendor may edit the quantity values for the various units comprising the preferred assortment in the tally 805 A-E. This allows the vendor to adjust the buyer's request according to the vendor's inventory, best means of transportation, etc. All of the vendor's quote information is referred to as price data set or the RFQ Line Item (tally) quote. [0055] Returning to FIG. 6A , the process continues to step 605 , where the server 230 normalizes the price of each RFQ Line Item (tally) quote from each vendor. The normalization of the vendor's price is a computation that evaluates the vendor's price utilizing data from a metric. The normalization process is carried out because each vendor may respond to the Line Items of an RFQ by quoting products that are different from a buyer's RFQ and/or have a different tally configuration. The normalization of the pricing allows the buyers to objectively compare the relative value of the different products offered by the plurality of vendors. For example, one vendor may produce a quote for an RFQ of one unit of 2×4×10, two units of 2×4×12, and three units of 2×4×16. At the same time, another vendor may submit a quote for three units of 2×4×10, one unit of 2×4×12, and two units of 2×4×16. Even though there is some difference between these two offerings, the price normalization process provides a means for the buyer to effectively compare and evaluate the different quotes even though there are variations in the products. The price normalization process 900 is described in more detail below in conjunction with the flow diagram of FIG. 9 . [0056] Returning again to FIG. 6A , at step 607 the vendor's quote information is communicated to the buyer's computer for display. As shown in FIG. 8B and described in detail above, the vendor's quote is displayed via a Web page that communicates the vendor's quote price 813 and other purchase information. In addition, the vendor's quote page contains a metric price 815 and a quote price versus metric price ratio 816 . The metric price 815 and the quote price versus metric price ratio 816 are also referred to as a normalized price data value. A ratio higher than one (1) indicates a quote price that is above the metric price, and a lower ratio indicates a quote price that is below the metric price. [0057] Next, at step 609 , the buyer or the administrator of the buyer pool compares the various products and prices quoted by the vendors along with the normalized price for each Line Item on the RFQ. In this part of the process, the buyer may decide to purchase one of the products from a particular vendor and sends a notification to the selected vendor indicating the same. The buyer notifies the selected vendor by the use of an electronic means via the server 230 , such as an HTML form, a chat window, e-mail, etc. For example, the quote Web page depicted in FIG. 8B shows two different quotes with two different tallies, the first quote price 813 of $360, and the second quote price 813 A of $320. If the buyer determines that they prefer to purchase the materials listed in the first quote, the buyer selects the “Buy!” hyperlink 820 or 820 A associated with the desired tally. [0058] If the buyer is not satisfied with any of the listed vendor quotes, the server 230 allows the buyer to further negotiate with one or more of the vendors to obtain a new quote. This step is shown in decision block 611 , where the buyer makes the determination to either accept a quoted price or proceed to step 613 where they negotiate with the vendor to obtain another quote or present a counter-offer. Here, the server 230 provides a graphical user interface configured to allow the buyer and one vendor to electronically communicate, using, e.g., a chat window, streaming voice communications, or other standard methods of communication. There are many forms of electronic communications known in the art that can be used to allow the buyer and vendors to communicate. [0059] The buyer and seller negotiate various quotes and iterate through several steps 603 - 613 directed by the server 230 , where each quote is normalized, compared, and further negotiated until a quote is accepted by the buyer or negotiations cease. While the buyer and seller negotiate the various quotes, the server 230 stores each quote until the two parties agree on a price. At any step during the negotiation process, the system always presents the buyer with an option to terminate the negotiation if dissatisfied with the quote(s). [0060] At decision block 611 , when a buyer agrees on a quoted price, the process then continues to step 615 where the buyer sends a notification message to the vendor indicating they have accepted a quote. As described above with reference to steps 603 - 613 , the buyer notification message of step 615 may be in the form of a message on a chat window, e-mail, by an HTML form, or the like. However, the buyer notification must be transmitted in a format that allows the system to record the transaction. The buyer notification may include all of the information regarding the specifications by RFQ Line Item, such as, but not limited to, the buy price, date, and method of shipment, and payment terms. [0061] The purchase-negotiation process 600 is then finalized when the system, as shown in step 617 , sends a confirmation message to a tracking system. The confirmation message includes all of the information related to the agreed sales transaction. [0062] Optionally, the process includes step 619 , where the server 230 stores all of the information related to RFQ, offers, and the final sales transaction in a historical database. This would allow the server 230 to use all of the transaction information in an analysis process for providing an improved method of obtaining a lower market price in future transactions and in identifying optimum purchasing strategy. The analysis process is described in further detail below. Although the illustrated embodiment is configured to store the data related to the sales transactions, the system can also be configured to store all of the iterative quote information exchanged between the buyer and vendor. [0063] Referring now to FIG. 6B , an embodiment of the unsolicited offer process 650 is disclosed. In summary, the unsolicited offer process 650 , also referred to as the unsolicited market purchase process, allows at least one buyer to view unsolicited offers from a plurality of vendors and purchase items from a plurality of vendors from the offers. The logic of FIG. 6B provides buyers with a forum that automatically manages, collects, and normalizes price quotes based on metric data. By the price normalization method of FIG. 6B , the server 230 creates an integrated forum where offers from a plurality of inherently dissimilar products can be obtained and normalized for determination of purchase. [0064] The unsolicited offer process 650 begins at step 651 where the plurality of vendors is able to submit offers to the server 230 . This part of the process is executed in a manner similar to step 603 of FIG. 6A , where the vendor submits a quote to the server 230 . However, in the Web page of step 651 , the server 230 generates a Web page containing several tallies from many different vendors. In addition, at step 651 , the server 230 stores all of the unsolicited offer data provided by the vendors. [0065] Next, at step 653 , a buyer views the offers stored on the server 230 . This part of the process is carried out in a manner similar to the process of step 603 or 607 where the server 230 displays a plurality of offers similar to the tallies depicted in FIG. 8A . [0066] Next, at step 655 , the buyer selects a metric for the calculation of the normalized price associated with the selected offer. As described in more detail below, metric data may come from publicly available information, i.e., price of futures contracts traded on the Chicago Mercantile Exchange, subscription services such as Crowes™ or Random Lengths™ accessed via the metric server adapter 435 (shown in FIG. 4 ), or internally generated metrics derived from the data stored in the server 230 . The normalization calculation, otherwise referred to as the normalization process, occurs each time the buyer views a different offer, and the normalization calculation uses the most current metric data for each calculation. The normalization process is carried out because each vendor will most likely offer products that may vary from products of other vendors and have a different tally configuration from those supplied by other vendors. The normalization of the pricing allows the buyers to compare the relative value of the different products offered by the number of vendors. The metric price for each selected offer is displayed in a similar manner as the metric price 815 and 816 shown in the Web page of FIG. 8B . [0067] Next, at decision block 657 , the buyer selects at least one offer for purchase. This is similar to the process of FIG. 6A in that the buyer selects the “Buy!” hyperlink 820 associated with the desired tally to purchase an order. The process then continues to steps 659 - 663 , where, at step 659 , the process transmits a buy notice to the vendor, then, at step 661 , sends a purchase confirmation to the tracking system, and then, at step 663 , saves the transaction data in the server database. The steps 659 - 663 are carried out in the same manner as the steps 615 - 619 of FIG. 6A . In the above-described process, the buyer notification may include all of the information regarding the specifications by RFQ Line Item, and data such as, but not limited to, the buy price, date, and method of shipment, and the payment terms. [0068] Referring now to FIG. 7 , a flow diagram illustrating yet another embodiment of the present disclosure is shown. FIG. 7 illustrates the catalog purchase process 700 . This embodiment allows buyers to search for a catalog price of desired commerce items, enter their purchase data based on the pre-negotiated catalog prices, and to compare those catalog prices with a selected metric price and the current market price, wherein the current market price is determined by the purchase-negotiation process 600 . [0069] The process starts at step 701 where the buyer selects a program buy catalog 443 . The program buy catalog 443 provides buyers with the published or pre-negotiated price of the desired products. Next, at step 703 , based on the catalog information, the buyer then enters their purchase data. Similar to step 501 of FIG. 5 and the tally shown in FIG. 8A , the buyer sends purchase data to the server 230 , such as the desired quantity of each item and the lumber species, grade, etc. [0070] The process then proceeds to decision block 707 where the buyer makes a determination of whether to purchase the items using the catalog price or purchase the desired product in the open market. Here, the server 230 allows the user to make this determination by displaying the metric price of each catalog price. This format is similar to the metric price 815 and 816 displayed in FIG. 8B . [0071] At decision block 707 , if the buyer determines that the catalog price is better than a selected metric price, the process then proceeds to steps 709 , 711 , and 713 , where a program buy from the catalog is executed, and the buyer's purchase information is stored on the server 230 and sent to the vendor's system to confirm the sale. These steps 711 - 713 are carried out in the same manner as the confirmation and save steps 617 and 619 as shown in FIG. 6A . [0072] At decision block 707 , if the buyer determines that the metric price is better than the catalog price, the process continues to step 717 where the buyer's purchase data is entered into an RFQ. At this step, the process carries out the first five steps 601 - 609 of the method of FIG. 6A to provide buyers with the price data from the open market, as well as provide the normalized prices for each open market quote. At step 719 , the server 230 then displays a Web page that allows the user to select from a purchase option of a catalog or spot (market) purchase. At decision block 721 , based on the displayed information, the buyer will then have an opportunity to make a determination of whether they will proceed with a catalog purchase or an open market purchase. [0073] At decision block 721 , if the buyer proceeds with the catalog purchase, the process continues to step 709 where the catalog purchase is executed. Steps 709 - 713 used to carry out the catalog purchase are the same as if the buyer had selected the catalog purchase in step 707 . However, if at decision block 721 the buyer selects the option to proceed with the market purchase, the process continues to step 723 where the RFQ generated in step 717 is sent to the vendor. Here, the process carries out the steps of FIG. 6 to complete the open market purchase. More specifically, the process continues to step 609 where the buyer compares the normalized prices from each vendor. Once a vendor is selected, the negotiation process of steps 603 - 613 is carried out until the buyer decides to execute the purchase. Next, the transaction steps 615 - 619 are carried out to confirm the purchase, notify the tracking system, and save the transactional data on the historical database. [0074] Optionally, the process can include a step where the server 230 stores all of the information related to program buy and metric comparisons and the final sales transaction in a historical database. This would allow the server 230 to use all of the transaction information in an analysis process for providing an improved method of obtaining the value of the program. Although the illustrated embodiment is configured to store the data related to the sales transactions, the system can also be configured to store all of the iterative quote information exchanged between the buyer and vendor. [0075] The analysis process allows the server 230 to utilize the sales history records stored in steps 619 and 711 to generate price reports for communication to various third parties as well as provide a means of calculating current market prices for products sold in the above-described methods. The sales history records are also used as the source for a metric, such as those used in the process of FIGS. 6A, 6B, and 7 . As shown in steps 619 , 663 , and 711 , the server 230 continually updates the historical database for each sales transaction. The analysis reporting process allows a buyer or manager of buyers to conduct analysis on the historical information. This analysis would include multi-value cross compilation for purposes of determining purchasing strategies, buyer effectiveness, program performance, vendor performance, and measuring effectiveness of forward pricing as a risk management strategy. [0076] Referring now to FIG. 9 , a flow diagram illustrating the logic of the normalization process 900 is shown. The logic of the normalization process 900 resides on the server 230 and processes the quotes received from commodity sellers. The logic begins at step 905 where quote data is obtained from the seller in response to the buyer's RFQ as described above. [0077] Next, at step 910 , routine 900 iteratively calculates the board footage (BF) of each type of lumber. Once all the totals are calculated for each type, routine 900 continues to step 915 where the server 230 calculates the total type price. [0078] At step 915 , routine 900 iteratively calculates the total type price for the amount of each type of lumber specified in the quote. This is accomplished by taking the total board footage (BF) calculated in block 910 and multiplying the total BF by the price per MBF specified in the quote. Once all the prices are calculated for each type, routine 900 continues to step 920 where the server 230 calculates the total quoted price. At step 920 , the routine 900 calculates the total price for the quote by summing all of the total type prices calculated at step 915 . [0079] At step 925 , routine 900 iteratively retrieves the most current price for each type of lumber specified in the quote from a predefined metric source(s). Metric data may come from publicly available information, i.e., price of futures contracts traded on the Chicago Mercantile Exchange, subscription service publications such as Crowes™ or Random Lengths™ accessed via the metric server adapter 435 (shown in FIG. 4 ), or internally generated metrics derived from the server database. Once all the prices are retrieved for each type, at step 930 , the routine 900 then iteratively calculates the market price for the quantity of each type of lumber in the quote. Once the totals for all types are calculated, routine 900 continues to step 935 where the routine 900 calculates the total market price for the quote by summing all the most current prices calculated in step 930 . Although this example illustrates that steps 910 - 920 are executed before steps 925 - 935 , these two groups of steps can be executed in any order, or in parallel, so long as they are both executed before a comparison step 940 . [0080] At step 940 , routine 900 compares the total quoted to the metric price to arrive at a comparative value. In one exemplary embodiment of the current invention, the comparative value is a “percent of metric” value. A value higher than one hundred (100) percent indicates a price that is above the metric rate, and a lower percent indicates a price that is below the metric rate. [0081] The operation of routine 900 can be further illustrated through an example utilizing specific exemplary data. In the example, a buyer sends out a request for a quote (RFQ) requesting a lot of 2×4 S&B lumber consisting of five units of 2″×4″×8′, two units of 2″×4″×14′, and five units of 2″×4″×16′. The buyer then receives quotes from three sellers. Seller A responds with a tally of six units of 2″×4″×8′, four units of 2″×4″×14′, and three units of 2″×4″×16′ for $287 per thousand board feet. Seller B responds with a lot of five units of 2″×4″×8′, one unit of 2″×4″×14′, and six units of 2″×4″×16′ for $283 per thousand board feet. Seller C responds with a lot of one unit of 2″×4″×8′, five units of 2″×4″×14′, and five units of 2″×4″×16′ for $282 per thousand board feet. Suppose also that the typical unit size is 294 pieces/unit, and the metric or reported market price for 2″×4″×8's is $287.50, for 2″×4″×14's is $278.50, and for 2″×4″×16′ is $288. [0082] Viewing the MBF prices for the respective quotes is not particularly informative, given that certain lengths of lumber are more desirable and priced accordingly in the marketplace. By processing the quote from Seller A using routine 900 , we arrive at a total MBF of 29.792, giving a total quoted price of $8,550.30. The selected metric price for the same types and quantities of lumber would be $8,471.12; therefore, the quoted price would have a percent of market value of 100.93%. Processing the quote from Seller B using routine 900 , we arrive at a total MBF of 29.400, giving a total quoted price of $8,320.20. The selected metric price for the same types and quantities of lumber, however, would be $8,437.21; therefore, the quoted price would have a percent of market value of 98.61%. Finally, processing the quote from Seller C using routine 900 , we arrive at a total MBF of 30.968, giving a total quoted price of $8,732.98. The selected metric price for the same types and quantities of lumber, however, would be $8,767.66; therefore, the quoted price would have a percent of market value of 99.38%. By looking at the percent of selected metric value, it is apparent that the price from Seller B is a better value. As shown in the methods of FIGS. 5-7 , this price normalization process allows users to compare inherently different offers having different quality and quantity values. [0083] In yet another example of an application of the normalization process, additional exemplary data is used to demonstrate the analysis of a transaction having one RFQ from a buyer and two different quotes from a seller, normalized to comparable product of another species. In this example, the buyer produces an RFQ listing the following items: one carload of Eastern SPF (ESPF) lumber having four units of 2″×4″×8′, four units of 2″×4″×10′, six units of 2″×4″×12′, two units of 2″×4″×14′, and six units of 2″×4″×16′. The vendor then responds with two different quotes with two different unit tallies and two different prices. The first response lists a quote price of $320 per thousand board feet, and a slight modification of the tally provides four units of 2″×4″×8′, four units of 2″×4″×10′, six units of 2″×4″×12′, three units of 2″×4″×14′, and five units of 2″×4″×16′. The second response quotes per the requested tally at a price of $322 per thousand board feet. Both quotes list the delivery location as “Chicago.” [0084] To display the quotes, the server 230 produces a Web page similar to that displayed in FIG. 8C , where the vendor's modified tally is displayed in highlighted text. The buyer can then view summary metric comparison or select the hypertext link “View Calculation Detail,” which then invokes the server 230 to produce a Web page as shown in FIG. 8D . Referring now to the Web page illustrated in FIG. 8D , the data produced by server 230 compares the response to a selected metric of a different species, Western SPF (WSPF), for items of the same size, grade, and tally. The market price for the same 2×4 tally of ESPF and WSPF are thus simultaneously compared. In an example, Eastern quoted at $322 per thousand board feet, Western metric (Random Lengths™ 6/26/2000 print price plus freight of $80 as defined in Metric Manager) for the same tally being $331.791. This metric comparison is also represented as Quote/Metric Value or Eastern price representing 0.970490, or 97% of comparable Western product. [0085] In review of the normalization process, the buyer must select a metric source for price information for a defined item given a set of attributes, i.e., grade, species, and size. The metric may then be mapped to the RFQ item for comparison and does not have to be the equivalent of the item. For instance, as explained in the above-described example, it may be desirable to map the market relationship of one commodity item to another. The most current pricing data for the metric is electronically moved from the selected source to the server 230 . As mentioned above, metric data may come from publicly available information, (i.e., price of futures contracts traded on the Chicago Mercantile Exchange), or subscription services, (i.e., Crowes™ or Random Lengths™ publications), or be an internal metric generated by the server 230 . This metric data is used in the normalization process for all calculations, as described with reference to the above-described methods. [0086] While various embodiments of the invention have been illustrated and described, it will be appreciated that within the scope of the appended claims, various changes can be made therein without departing from the spirit of the invention. For example, in an agricultural commodity, an order for Wheat U.S. #2 HRW could be compared to a selected metric of Wheat U.S. #2 Soft White, similar to how different species are analyzed in the above-described example. [0087] The above system and method can be used to purchase other commodity items, such as in the trade of livestock. In such a variation, order information such as a lumber tally would be substituted for a meat type, grade, and cut. Other examples of commodity items include agricultural products, metals, or any other items of commerce having several order parameters.

A system includes at least one server that implements a metric server adapter and a metrics application. The metric server adapter includes governing logic that manages an evaluation service and predefined instructions and/or data used to provide the evaluation service. The metrics application executes the evaluation service in coordination with the metric server adapter. The server receives or retrieves price data sets, at least one of which represents an unequal offer. The metrics application obtains time-dependent metric data including market reference price data for one or more responsive items, dynamically discovers a difference in the attribute data, and defines offer-specific instructions for adapting the metric data. One or more adjustment values applied to the market reference price data transforms the market reference price data. A comparative metric comprising a differential ratio or index value compares the price data in the offer with the offer-specific market reference price data values.

Related Applications The present invention is particularly directed to use in an adaptive inference testing system which will employ varying features and functions, described in differing aspects in any one or more of the following copending patent applications, including this one, all filed concurrently and assigned to the present assignee: Ser. No. 07/433,612 for "INTERACTIVE ADAPTIVE INFERENCE SYSTEM"; Ser. No. 07/433,591 for "SYSTEM FOR DISPLAYING ADAPTIVE INFERENCE TESTING DEVICE INFORMATION"; Ser. No. 07/433,335 for "METHOD FOR CALCULATING ADAPTIVE INFERENCE TEST FIGURE OF MERIT"; Ser. No. 07/433,594 for "UNPREDICTABLE FAULT DETECTION USING ADAPTIVE INFERENCE TESTING TECHNIQUES". BACKGROUND OF THE INVENTION The present invention relates to an adaptive inference testing device and, more particularly to an array structure for use therein. In the field of electronics in general and in printed circuit board assembly in particular, electronic components are generally mounted, affixed, plugged into or otherwise associated with printed circuit boards. Such electronic components may be analog devices, digital devices, integrated circuits and the like. The boards, in turn, usually have electrical contacts along one or more sides thereof for plugging into connectors. On a typical personal computer, for example, some five to ten boards are provided and are associated, by means of connectors, with a so-called mother board. Of course, more sophisticated machines would tend to have a greater number of boards and less sophisticated instruments would have tend to have fewer boards. As the technology of electronic devices advances and as the consumer market for advanced products matures, not only does the functional complexity and the number of manufactured machines increase, but so too may the number of components per board increase. This makes it difficult to directly access all of the test points required to test a loaded board completely. Finally, components mounted on the boards become ever more powerful and more difficult to test as new functions are required. It therefore has become increasingly important to enhance procedures for testing proper operation of components, boards and machines. To the extent that such testing procedures can be improved, more efficient methods and more accurate methods are ensured. For purposes of this description, the term "adaptive inference" means the ability to predict the cause of a previously unobserved fault from the relationships with other known fault information. Also for purposes of this description, the term "unit under test (UUT)" is used to identify any component or assembly to be tested. Heretofore, UUTs were tested by technicians with the aid of certain instruments as simple as a voltmeter or as complex as a mainframe computer. Such testing methods were necessarily time consuming and labor intensive. More recently, programmable systems have been used to test specific UUTs. These systems tend to be more efficient than manual methods, by allowing a greater number of UUTs to be tested in a given amount of time. But in order to use these programmable systems to test every possible condition of a component or board, every possible stimulant must be applied to the UUT and every possible response must be analyzed or at least compared with its associated proper reference response. Even on a simple UUT, unanticipated problems can arise in many ways. Previous methods required a test engineer to program each of these possible faults into a machine. This required enormous amounts of programming. Over 25,000 lines of code and six months of effort were not unusual. The present invention eliminates this programming effort for fault isolation by mathematically comparing a new fault to previously stored faults. A figure of merit is derived and displayed to indicate likely causes and closeness to known faults. For instance, a certain circuit node may be shorted to ground and the faults recorded and stored in memory. When the same node is shorted to +5v, the acquired data is not going to be identical, but may be very close. In a traditional programming environment, two separate programs would be needed to cover both those cases. But the present invention indicates a high probability (figure of merit) that the indicated node is the source of the fault. Powerful display tools in accordance with the present invention, such as waveform displays with color highlighting to show discrepancies, aid in localizing the troublesome area. A figure of merit less than 100% for faults never before experienced can signal the operator to investigate. In the above example, when the operator discovers that a node is stuck high (not grounded), with a single keystroke the new fault can be added to memory. If the fault occurs again, the message displayed indicates this new fault with a high figure of merit: that same node is likely to be stuck to +5v. The next time the test is run with the same node stuck high, the system displays the message and indicates the second most likely diagnosis is the same node stuck low with a figure of merit less than 100%. In this way, the system accumulates a representation of knowledge that it has gained in the past. It can infer things it has never seen. It operates similarly to the way that a human operator would debug a circuit. Moreover, the system improves with time and, of course, it never forgets. A particularly vexing problem relates to the fact that testing procedures conventionally are performed in a serial manner. That is, the UUT is tested by applying one stimulus thereto and tracing its effect through the UUT, finally arriving at the overall UUT response, which is checked against a reference response. With sophisticated, complex electronic devices, having a great number of possible and appropriate stimuli, each resulting in a different response, the serial technique of the prior art is woefully inefficient and time consuming. Moreover, if a plurality of responses is acceptable for a given stimulus, prior art testing systems are generally inadequate to detect proper operation within a range of values. Baker et al. U.S. Pat. No. 4,847,795 discloses a system for diagnosing electronic assembly defects. The system has a knowledge base for storing information on UUT and receiving current test failure. The system has a pattern search which compares current test data to stored information. A voting section recommends a repair process. The knowledge base is updated with information as to whether or not the repair eliminated the defect. Hogan Jr., et al. U.S. Pat. No. 4,841,456 discloses a system in which an artificial intelligence system is interfaced with an automatic test system such that the actions of the AI are indistinguishable from those of a human operator. The automatic testing system includes an automatic test equipment controller, at least one test instrument and a UUT. There is a storage means for storing a functional test procedure (FTP) for the UUT. The FTP data set contains the results obtained by executing the FTP. An expert system means processes the FTP data and indicates when a failure has occurred and, if possible, the defective UUT portion that may have caused the failure. The expert system means produces output data identifying the defective UUT portion. The automatic test system may also comprise a diagnostic test procedure for the UUT should the expert system determine that further testing is required. It would be advantageous to provide an adaptive inference testing system capable of massively parallel operations. It would also be advantageous to provide an adaptive inference testing system with an array structure. It would also be advantageous to provide such a testing system with a method for comparing test response data with reference response data. It would also be advantageous to provide such an adaptive inference testing system with means for comparing actual test data with a range of proper responses. It would also be advantageous to provide an adaptive inference testing system with a library of errors, which can be updated by an operator. SUMMARY OF THE INVENTION In accordance with the present invention there is provided an adaptive inference system for testing electrical or electronic devices or assemblies. A mechanism is provided for performing position-dependent, time-ordered tests upon electrical or electronic devices in order to obtain a test data array. A mechanism is also provided to define a reference array containing acceptable data for comparison with test data. A comparator is connected to the test data array and to the reference array for providing an error array. An error array library is also provided, which contains accumulated error data. Finally, an error array comparator is connected between the error array library and the error array providing a diagnostic analysis of the electrical or electronic devices or assemblies. BRIEF DESCRIPTION OF THE DRAWINGS A complete understanding of the present invention may be obtained by reference to the accompanying drawings, when taken in conjunction with the detailed description thereof and in which: FIG. 1 is a perspective view of the MFI and MCP of the present invention; FIG. 2 is a perspective view of the probe assembly; FIG. 3 is a block diagram of the MFI and MCP of the present invention; FIG. 4 is a schematic representation of a display on a video monitor; FIG. 5 is a schematic representation of data arrays used in accordance with the present invention; FIG. 6 is a flow chart of the testing process in accordance with the present invention; and FIG. 7 is a schematic representation of the testing process in accordance with the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is illustrated the preferred physical embodiment of the present invention. The invention includes a microprocessor-based Multifunction Instrument (MFI) 10. The MFI 10 supplies system control and power and can perform complex tasks without requiring a host PC 12, such as is manufactured by IBM CORP. However, when the MFI 10 is connected to inferential software, described hereinbelow, which is hosted on the PC 12, other testing functions can be performed, as described herein. The MFI chassis provides an optional printer connector, not shown, communications connector 14, and a GPIB connector, not shown. A keypad 16 is built into the MFI chassis providing an input interface for stand alone operation. The keypad 16 contains function keys 18 used to respond to MFI menus and data displays, described later herein. A video monitor 18 is connected to the MFI 10 via a monitor cable 20. The video monitor 18 is used during stand alone operation to view data displays and menus, described later herein. The MFI chassis has two hardware modules called plugins 22 and 24 that configure the MFI 10. There are plug-ins 22 and 24 for data acquisition, pattern generation, EPROM programming, EPROM emulation and other functions. The MFI 10 must have at least one plug-in (two plug-ins are shown in the FIGURE) 22 and 24 installed in order to operate as a testing tool. Connected to the plug-ins 22 and 24, in turn, are probes 26, at least one or two for each plug-in 22 and 24, only one of which is shown in FIG. 1. Different types of probes 26 can be used with a particular type of plug-in 22 and 24 to achieve different functions. Referring now also to FIG. 2, there is shown a perspective view of the probe assembly. Probes 26 extend from the plug-ins 22 and 24 (FIG. 1) to test leads 28 attachable to a unit under test (UUT), not shown. In this way, probes are the conduit between the UUT and the MFI 10. Probes 26 contain a set of ground pins 30 and signal pins 32 that are connected by means of test clips 34 to the UUT. Each plug-in 22 and 24 and probe 26 must be correctly matched to perform desired functions (e.g., data acquisition, pattern generation, and continuity testing). A label 36 identifies the function of the probe 26. Referring now to FIG. 3, there is shown a block diagram of the preferred embodiment of the present invention. The inventive circuit testing tool has the microprocessor-based Multifunction Instrument (MFI) 10 connected to an MFI Control Program (MCP) 11 by means of a GPIB interface (shown by arrow), which MCP 11 is hosted on the personal computer 12 (FIG. 1). A printout of the MCP program listing is printed as Appendix A, filed with the aforementioned patent application No. 07/433,612 titled "Interactive Adaptive Inference System", and is herein, incorporated by reference (A copy may also be found in the patented file of this application). Connected to MFI 10 is a unit under test (UUT) 38. UUT 38 may be a large, complex printed circuit board, not shown, or a smaller component that may be disposed on or near such a board. It should also be understood that such a component can be displaced from a larger assembly or disconnected entirely therefrom. Any electrical or electronic device or assembly can be used with the system. The MFI 10 contains a high speed random access memory 42, an address counter 44, a data clock control 46, a state machine 48 and buffer memory 50. State machine 48 is connected to data clock control 46 by means of lines 48a. Data clock control 46 is connected to address counter 44 by means of lines 46a. State machine 48 is connected to plugins 22 and 24 by means of lines 48b. Address counter 44 is connected to RAM 42 by means of lines 44a. RAM 42 is connected to memory 50 by means of line 42a. Connected to plug-ins 22 and 24 are probes 26 and Analog/Digital/Drive/Sensor (ADDS) boards 40. The MFI 10 operates as a logic analyzer, digital pattern generator, continuity tester, signature analyzer, microprocessor, disassembler, digital storage oscilloscope, analog waveform generator, EPROM programmer or EPROM emulator. These functions can be controlled by the MFI 10 in the stand alone mode or by the MCP 11 in the coupled mode. When the MFI 10 is coupled with the MCP 11, the combination of devices can run automatic tests and can learn from the results of completed tests. MFI 10 runs an internal firmware program generating menus and data displays; responding to keypad inputs (stand alone mode); controlling the operation of the address counter 44, data clock 46, ADDS boards 40, and trigger control 48; and responding to the control status and data communication from the host PC 12 running MCP software. A plurality of MFI's may be stacked. When in this mode, one MFI 10 acts as the master processor controlling interfaces, not shown, between the other processors. The multiple MFI's can simultaneously acquire (read) and generate (write) digital and analog data, not shown. Data is acquired or sent via the ADDS boards 40. The MFI 10 typically contains several digital and analog ADDS boards 40. The functionality of ADDS boards 40 (analog/digital, drive/sense) is controlled via MFI menus, described in greater detail hereinbelow. Attached to the ADDS boards 40 are the plug-ins 22 and 24, used to configure the MFI 10 for the data acquisition or pattern generation. Data output to or input from the UUT 38 via the ADD boards 40, plug-in 22 and 24, and probes 26 is resident in the RAM 42. The RAM 42 is structured into 96 channels with each channel being 2K samples deep. All data is stored in the RAM 42. Such data is stored in the RAM 42 as digital data, but represents the analog form. That is, analog data input is converted to digital form prior to storage in RAM 42 and converted from digital to analog form when output from RAM 42. RAM control is performed by the address counter 44, data clock control 46 and trigger control 48. The MFI 10 operates in three states: a) an IDLE state where the data clock 46 is OFF, the address counter 44 is OFF, and no data is being written to or read from the RAM 42; b) an ARMED state where the data clock 46 is ON or halted, the address counter 44 is ON and data is being written to or read from the RAM 42; and c) a TRIGGERED state where the data clock 46 is Stopped, the address counter 44 is stopped, and the contents of the RAM 42 are Frozen. When the MFI 10 is ARMED, it is active either generating data for or acquiring data from the UUT 38. The trigger control 48 determines the length of time the data clock 46 will be operable (i.e., how long the MFI 10 will be ARMED). Trigger control 48 monitors the acquired data searching for sequences of trigger patterns. A trigger pattern is a combinational state of the acquisition channels of the MFI 10. States can be high, low or "don't care". Several trigger patterns can be used simultaneously. Once the specified sequence of trigger patterns has been recognized, the MFI 10 enters a TRIGGERED state. The state machine 48 counts the number of samples past the trigger event. Several triggers can be used to start and stop data collection. Once the RAM 42 is full or the last trigger is reached, the data clock 46 and address counter 44 are stopped and the RAM 42 frozen. The MFI 10 reads the contents of the RAM 42 into local memory 50. Once data is in local memory 50, the MFI 10 can create a data display that is output to the video monitor 18 or transferred to the PC 12 for analysis. The address counter 44 points to a sample address in the RAM 42 where data is either written into or read out of the ADDS boards 40. The data clock 46, which may be sourced externally, determines the speed that the address counter 44 counts through the RAM channels and determines the time between samples. Data clock 46 can be made to operate at a speed greater than the speed at which the UUT 38 would normally operate. In the stand alone mode, the MFI 10 operation described above is controlled by menus 49 accessed via the keypad 16 and viewed on the video monitor 18. Each menu 49a-49k has a series of questions that, when answered, provides the capability to modify or adjust MFI operation. The MFI 10 reconfigures these menus 49 to show only those questions and answers that relate to the types of plug-ins 22 and 24 and probes 26 that have been installed. The first menu that appears when the MFI 10 is activated is the configuration menu 49a. This menu 49a provides information about the present configuration of the MFI 10, such as what plug-ins 22 and 24 are attached, whether the MFI 10 is stacked or uncoupled, which machine or operating state the MFI 10 is in, and what SETUP mode is selected. A SETUP mode is the set of all MFI 10 operating parameters a user can modify on all the menus plus one display parameter. There are two complete setups allowing a user to change setups without having to remodify all the menus. In addition to status information, this configuration menu 49a provides the capability to change configurations. A communication menu 49b sets up the printer ports and the communication ports on the MFI 10. This menu can be accessed only from the configuration menu 49a. The data parameter menu 49c provides the capability to select the display mode, trigger delay, probe and channel options, and auto arm. The trigger delay provides the capability to adjust the number of samples to be acquired after the sequence has been satisfied. The clock menu 49d provides the capability to determine what points in time are to be sample points. Sample points are those points at which acquisition channels sample data and when generation channels output data. The trigger pattern definition menu 49e provides the capability to set up to 14 trigger patterns. The trigger pattern is a set of logic levels, one logic level defining each acquisition channel. Logic levels can be defined as HI, LO, and DON'T CARE for each acquisition channel. When these logic levels simultaneously occur on all the acquisition channels, the trigger pattern has occurred. The trigger sequence menu 49f provides the capability to instruct the MFI 10 to perform different actions as different trigger patterns occur. The pattern generation menu 49g provides the capability to control the pattern generation plug-ins 22 and 24 and probes 26. There are two sources of patterns: algorithmic pattern, useful for generating analog signals; and "from the screen" pattern source which uses data records in the MFI buffer memory 50 as pattern sources. The continuity test menu 49h controls the continuity tester plug-in 22 and 24 and probe 26. The analog menu 49i provides the capability to specify that the data records of selected probes 26 be displayed on the timing display shown on either video monitor 18 or PC 12 (FIG. 1) as analog waveforms. The signature analysis menu 49j provides control over the signature plug-in 22 and 24. The EPROM programming menu 49k provides the capability to control the EPROM plug-in 22 and 24 and probe 26. Data displays that appear on video monitor 18 or PC 12 provide the capability to observe and modify data acquired or generated by the MFI 10. There are four data displays provided with the MFI 10: a) timing display, not shown, displaying waveform data. The timing display acts as an adjustable window on the data record, not shown. The data record is larger than the window, but the window may be moved back and forth or up and down to show the whole data record. The data may also be magnified under the window for more precise observations. b) binary/hex display. These standard displays, well known in the art and not shown in detail herein, provide the capability to examine the data records sample by sample and channel by channel; c) octal display. This standard display, well known in the art and not shown in detail, displays the data record as a sequence of octal data; and d) processor disassembly displays, providing the capability to observe the processor code execution in the assembly language of the UUT processor. Referring now also to FIG. 4, there is shown a typical timing diagram displayed on video monitor 18 or the PC 12 (FIG. 1). The timing diagram display illustrates some of the key concepts described above. This example shows twelve digital channels and one analog channel. In the simplified example observe the following items: DATA CLOCK 72 The user selected sampling rate for the data shown in this display is 20 ns per sample. The dotted horizontal line 73 in the middle of the display shows the actual positions of the sample clock. TRIGGER POSITION 74 The trigger event 75 is indicated by the vertical dashed line. At this point in time, the states of the acquisition channels matched the user described trigger pattern. "Trig=00303" indicates the position of the trigger event as sample number 303 in the record. SCREEN POSITION 76-78 "S=0248" indicates that the left edge of the screen 76 is displaying the 248th sample of the record. At the top right corner 78 "0359" indicates that the right edge of the screen is displaying the 359th sample of the record. Typically, the earliest sample in the record is sample 0 and the last is sample 1023. The last sample number is a function of record size. CHANNELS 80 The indications on the left edge of the display are the channel labels. These labels identify the plug-in probe pin 32 (FIG. 2) that was connected to the point in the user's circuit that generated the waveform 82 to the right of the label. WAVEFORMS 82 The waveforms displayed to the right of each channel label are representations of digital data captured by the MFI. This is the result of ACQUISITION. MFI STATUS 84 This indicates MFI status as either ARMED, TRIGGERED, or as evidenced in this example, IDLE. MAGNIFICATION 86 This indicates the resolution of the display. In this example, MAG=1 shows separate sample points at the highest resolution, 112 samples across the display. TIMING CURSOR INDICATORS 88 These vertical solid lines are used to locate the signal events within the data record or to measure the time period of a signal event. TIMING CURSOR 1 POSITION 90 AND TIMING CURSOR 2 POSITION 92 Indicate the sample number positions of the timing cursors. DIFFERENCE BETWEEN TIMING CURSORS 94 Indicate the number of samples or time units between the timing cursors 90-92. VOLTAGE CURSOR INDICATORS 96 Measure the amplitude of the analog waveforms. DIFFERENCE BETWEEN VOLTAGE CURSORS 98 Indicates the number of vertical divisions between the voltage cursors 96. ANALOG VOLTS PER DIVISION 100 This indicates the vertical scale of the analog channel. Divisions are actually the pixel size on the display. When this example has completed its activities, the MFI 10 has obtained a set of data and stored it in the RAM 42. MFI stand alone operation (FIG. 3) is summarized in the following example of the MFI 10 functioning as logic analyzer. The following example is prescribed for explanatory purposes only and is not intended to limit the scope of the invention as defined by the appended claims. The MFI 10 is configured for this example as follows: capacity of 32 channels of timing data represented by two DDA50 plug-ins 22 and 24 (each with 16 channels digital) and each plug-in 22 and 24 with two P8v probes 26 (each probe with 8 channels available). The probes 26 are attached to a set of circuit boards 38. Each acquisition channel 32 (FIG. 2) on the probes 26 is assigned to a point in the unit under test 38 (FIG. 3). Each channel acquires logic level samples (1's and 0's) from the point in the UUT 38. Sampling occurs at points in time (sample points) determined by the operator's selected data clock 46. An analog channel uses eight digital channels in the preferred embodiment to represent the analog wave form. Sampling begins when the MFI 10 is ARMED. The MFI 10 is ARMED when one of the following occurs: The Arm Key Trig Key on the keypad 16, or the MFI 10 receives an Arm Key or Trig Key command over the communications port 14 from the MCP software 11, while the MFI 10 is IDLE (not ARMED). The MFI 10 is triggered while in AUTO-ARM mode. Sampling stops when one of the following occurs: The MFI 10 is disarmed by pressing the Arm Key on the keypad 16 or sending the Arm Key command to the communications port 14 to the MCP software 11, while the MFI 10 is ARMED. The MFI 10 is triggered. The MFI 10 is triggered by one of the following: The occurrence of a specified sequence of trigger patterns followed by a trigger delay number of data clocks 46. The Trig Key on the keypad 16 is pressed or the Trig Key command is sent to the communications port 14 to the MCP software 11. When the MFI 10 is triggered it will display the acquired data on the video monitor 18 or on the PC 12. Each channel maintains a data record of the most recent samples. The number of samples in a channel's record is determined by the plug-in 22 and 24 type and data clock 46 for that channel. The record size can also be affected by concurrent pattern generation within the MFI. Generally, the record size is from 512 to 8192 samples. A trigger pattern is an operator defined combinational state of input channels. For a particular trigger pattern, the user can assign a state for each acquisition channel, a 1 or a 0 or an x (for "DON'T CARE"). When this combination of states occurs simultaneously on the acquisition channels, the defined trigger pattern is said to have occurred. ______________________________________ TRIGGER PATTERN______________________________________PROBE # 22221111111100000000Pin # 32107654321076543210TP01 XXXXXXXXXXXXXXXXXXXX______________________________________ When the MFI 10 is triggered, the channel records are available in their final form to be viewed on the MFI's display screens. These records may be viewed as timing diagrams (FIG. 4) or as one of many data domain displays, including microprocessor disassembly, that the MFI 10 can generate. The above discussion on the invention data acquisitions/sending operations is the same in either the stand alone mode (MFI 10 controls the activity) or the coupled mode (MCP 11 controls the activity). Referring now again to FIG. 3, the MFI control program (MCP) 11 provides the capability to use PC based technology to control and enhance the performance of the MFI 10. The MFI 10 is connected to the MCP 11 by standard interfaces 14 (e.g., RS-232 communications port or GPIB IEEE-488 interface). The MCP 11 operates as a menu driven, interactive program organized into six major functions: control 52, editing 54, filing and transfer 56, viewing 58, testing 60, and other 62. The control menu 52 provides the capability to control the MFI 10 directly, including the MFI menus 49. There are two modes associated with this menu: a) blind control provides keys on the PC keyboard as replacements for the keys on the MFI keypad 16. Control is exercised by using the keyboard keys to interact with the menus and displays produced by the MFI 10; and b) remote control provides the capability to replace both the MFI keypad 16 and monitor 18 with the PC 12. The PC 12 displays the current MFI display on one half of the monitor 18 and displays valid MCP control keys on the other half. Editing menus 54 provide the capability to change or modify data contained in the MCP memory 50. Data can be edited using either the digital/analog waveform display (such as illustrated in FIG. 4) or the hexadecimal character display. Additional functions are provided to edit the waveform display; mark, unmark, copy, fill, and duplicate digital waveform segments; generate digital counting patterns; generate simple analog waveforms; and perform mathematical operations on analog waveforms. Filing and transfer menus 56 provide the capability to control the transfer of information between the MFI 10 and the MCP 11. It allows the MCP 10 and MCP 11 to share setups and data. Setups are the copy of all working menu variables and reflect menu settings (MFI menus 49a-49k and MCP menus 52-62). Filing functions provide disk accessing and storage on the PC disk system. Viewing menus 58 provide the capability to select the data being displayed, to label and arrange the order of the channels in the display, to control the resolution of the display, to display specific portions of the data, and to select between a waveform representation and a hexadecimal character representation. Testing menus 60 provide the capability to test chips, circuits, PC boards, and other electrical or electronic devices or assemblies. The MFI 10 is automatically reconfigured for a specific test through the filing functions. Other menus 62 provide the following miscellaneous functions: setting communications baud rate, copying among buffers, listing files in the working directory, changing directories, outputting a control byte to the parallel port, uploading and downloading EPROM images. In addition to the aforementioned menus 52-62, the MCP 11 provides the capability to record operator commands as they are entered from the PC 12 (FIG. 1) keyboard or keypad 16 and to execute these sequences on command, generating the same activity as when they were first recorded. The macro functions 64 allow the MCP 11 to run tests without operator interaction. Referring now also to FIG. 5, there is shown a schematic representation of data arrays as used in accordance with the present invention. In operation, test vectors 102 are applied to a unit under test (UUT) 38. While UUT 38 is usually a printed circuit board, it may also be a single device. The invention contemplates several ways of creating test vectors 102. If UUT 38 contains a microprocessor or other intelligence, and actually performs a function when the power is turned on, MCP 11 (FIG. 3) can learn the function of UUT 38 by connecting to it and observing the normal response. Alternatively, an operator can visually create test vectors using a highly interactive graphical user interface and editor. Another method to create test vectors is to download simulation data from a computer aided design (CAD) system database, not shown, to PC 12. When a device or a board is designed, a simulation using a CAD system is often created to validate the design. While such a simulation may not be perfect information for the test process, it is usually a good starting point. Test vectors 102 are applied to UUT 38 to acquire data for the board under test 38. An acquired data plane or array 104 is generated as a result of applying test vectors 102 to UUT 38. Circles 104a-104c in FIG. 5 indicate information gathered. The two-dimensional representation of this plane of information 104 illustrates one of the unique features of the invention. Wherever a test point is interrogated, information is gathered continuously in the form of a data array. For purposes of this description, it is useful to know that reference data are the responses and information gathered from a known good board. Data represented by three circles 104a-104c on the acquired data plane 104 are compared to reference data 106a, 106b on reference data plane 106. A single test is sufficient to obtain a reference. A number of good boards 38 can be used to create a tolerance data plane 108. Since a known good board can have variations that are considered normal, the tolerance plane 108 is a representation of the normal variations of a known good board. For example, a pulse might be one millisecond wide on the board that is being measured. But it is quite likely that a range of, say, from 0.9 to 1.1 milliseconds is valid normal acceptable data. One could measure a plurality of good boards (e.g., 50 boards) and vary their power supply and temperature to learn normal variance from the good boards. Alternatively, one can use an interactive graphical user interface, hereinbelow described in greater detail, and "tolerate out" (i.e., specify) that range of values, 0.9-1.1 milliseconds. Thus, test vectors 112 are applied to UUT 38 to acquire data 104. Reference data 106 from one good board is already in memory. A simple logical compare (EXCLUSIVE NOR) is performed on a bit-by-bit basis hundreds of thousands of times between the acquired data 104 and the reference data 106. Any deviations between data in the two planes 104, 106 are then compared to data in the tolerance data plane 108. Here a logical AND operation is used as a mask. Any deviations that have been seen in the first array operations are now compared to this mask 108 again. In this way, massively parallel logical operations occur hundreds of thousands of times. By the time the error plane 110 is reached, all deviations which have been observed or predicted by simulations are identified. The mode of analyzing data is far different than traditional methods. As a result, faults are defined that would simply be missed by other kinds of test systems. To build tolerance, an operator decides that the deviations are acceptable; acquired data 104 is compared to reference data 106 and any variances within the tolerance plane 108 are accepted. Once tolerance has been built up, the system is ready to check for errors. Acquired data 104 not favorably compared to reference data 106 nor within tolerance plane 108 results in errors, stored in an error plane 110. An error is defined as an acquired response that is not tolerated out. A pass/fail, go/no-go test can be performed at this point. If there are no errors, the board under test 38 passes. If, however, errors exist, the system can memorize data patterns of faults as well as data patterns of known good boards. If there is a variance, the system can identify that condition and associate that pattern with an English language message 116 previously provided by an operator. For example, "U2, pin 3 Shorted to Ground" would be the sort of message that an operator might see, which is associated with a purely internal mathematical representation. One advantage of this diagnosis is that the system can provide an associated fault with an English language message, which an unskilled operator can then use to debug a UUT 38. The system can store many of these fault patterns, each under a different message. In the process of learning what a good board is or in the process of creating reference data 106, an operator can train the system with a certain number of known faults. In this case, the operator essentially provides the system with a knowledge of faults. For example, U2, pin 2 can be shorted to U2, pin 3. When the test is run, it will fail and the operator enters the appropriate error message. This fault is added to a directory 116 with that English language message. This process can be repeated for different intentionally provoked faults. Subsequently, a test is performed on another UUT 38, resulting in an error. The board fails and the system checks its memory to see if the fault patterns match any that has been seen before. If such a match occurs, the appropriate English language message is displayed. In such a case, the system indicates close to 100% certainty that an error is caused by a fault previously stored. Referring now also to FIG. 6, there is shown a flow chart of the testing process. Test vectors and test parameters are entered into the MCP 11, step 118. These vectors and parameters are downloaded, step 119, into the inferential software 68 (FIG. 5). As explained above, the system enters an ARMED state, step 121, where data is acquired from the UUT 38 until the Trigger is encountered when data is sent to the MCP 11 via the interface 14. Reference and tolerance data are developed, step 120. Initially, these data are developed by setting the reference data set to test data and setting the tolerance data to zero or by using the waveform editor 54 (FIG. 1). Test data acquired from the UUT 38 is compared to the reference and tolerance data, step 124. Results, step 122, that differ from the reference and tolerance data are entered into the fault database. From known good boards, the tolerance data is increased by the difference, step 120. Failure data is passed to fault image and displayed, step 126. Fault isolation improves with increased fault database size. The operator directs any newly discovered fault to the fault database, step 128. At this point in the process the operator can edit any previous diagnosis. The operator can set the testing options, step 130, and the diagnosis options, step 132. Referring now again to FIG. 5, the inferential software 68 provides the capability to "learn" to recognize fault conditions in analog and/or digital signals. A fault directory is either created by simulating failures or by learning faults as they occur during normal testing. Once fault data is stored in memory, a newly-detected fault can be compared with the stored faults. A relationship between the stored fault data and the detected fault is determined. The system indicates the cause of the detected fault to the operator based on stored fault data that is most probably related to the detected fault. This system analysis and range of potential causes can be evaluated by an operator. Referring now to FIG. 7, there is shown a schematic representation of the inferential software principles behind the testing strategies. These strategies are summarized below: Repeatable Results The principle utilized in testing assumes that the operation of a circuit may be judged by examining its operating signals. The first step in developing any test is to devise test vectors and acquisition points that, when applied to the unit under test 38, will produce the same results repeatedly. A device that is working properly will produce a predictable and identifiable result. It is assumed that any deviation from predicted operation is produced by an error in the UUT 38. That UUT 38 has failed the test. Reference and Tolerance Comparison Even devices which are working properly may show some normal drifting and timing jitter between successive iterations of the same test. The test mechanism was designed to cope with this problem. In order for the MCP 11 to be able to determine when a device passes and when it fails, the software must have a standard to judge the incoming results (the Acquired data 133). This standard is referred to as the reference image 134. In most cases, the reference image 134 is simply a copy of the first set of results returned by a good device. The test is performed again and the new results are compared against the old results and stored in the reference image 134. Any differences that occur between successive tests of the same device are recorded in the tolerance image 136. Once all the deviations of the good device are characterized, the good device will always pass because any deviations from the norm have been recorded in the tolerance image 136 and are ignored. This procedure is then repeated with other known good UUTs 38 until the tolerance image 136 has become broad enough to include all the discrepancies which normally occur among properly working UUTs 38. Error Pattern Processing The inferential software, shown in FIG. 7 with dashed lines and identified by reference numeral 68, assumes that, depending upon the specific test configuration, unique faults in the unit under test 38 will produce unique patterns of discrepancies. One fault, a bad chip for example, might cause massive failures all across four channels; whereas another fault, say one signal stuck low, might cause failures during only part of the test on only one channel. In each case, the position, timing and location of the resulting test deviations show that each fault produces a very different pattern of failures in the test data 144. The function of the inferential software 68 can be expressed as follows: 1) Reduce the actual test failure data to a failure synopsis, or fault pattern, which is saved in a database file assigned automatically on a test by test basis. 2) Associate a specific fault diagnosis or comment with each fault pattern stored in the database 138. 3) Compare the incoming fault pattern with all patterns in the database and display the diagnosis descriptions of patterns that match closely 142. 4) Provide a menu-driven interactive interface for developing, utilizing, and maintaining the fault diagnostic databases. Inferential software 68 keeps a record, or mathematical representation, of the specific error patterns that occur in the process of testing. When a fault pattern is added to the database 138, it is associated with an operator-defined 64-character string referred to as the fault diagnosis 140. Initially, the fault patterns can be associated with a descriptive comment. As the causes for these errors are determined, the initial comment can be replaced with the diagnosis. The next time an error occurs, the inferential software 68 will report any fault patterns in the database 138 that are similar to the new fault pattern. Once an error has been identified by the user, the inferential software 68 will be able to recognize and diagnose that error with a high degree of accuracy because it will recognize that fault's unique pattern. Furthermore, even when processing a pattern for the first time, the inferential software 68 will correlate to the most likely fault already stored and will display at least the best match it can find. The inferential software 68 is an extension of the testing mechanism already inherent in the MCP 11 (FIG. 3), so all user access to the inferential software 68 is achieved through the testing functions menus 60 (FIG. 3) of the MCP 11. The inferential software database 138 is maintained in two files (in addition to those generated by the MCP 11 itself). The names of these fields are derived from the MCP 11 data file name and the currently loaded storage frame number. For example, if the full filename of the data file currently open is "TSTNAME.DAT", the following files would be created during test development and diagnosis: TSTNAME.22 Reference file 106 and tolerance file 108 for frame 22. TSTNAME.F22 Inferential software database 138 file of fault descriptions for frame 22. TSTNAME.X22 Inferential software database 138 file of fault patterns for frame 22. The fault description file 137 name is formed, as shown above, by taking the reference file 106 name and inserting the letter `F` between the period `.` and the frame number. This file consists of linefeed terminated strings, each within a fixed 80-character cell. It is possible to use the DOS "TYPE" command or any standard ASCII text editor to display this file. The index number refers to the fault's actual position in the file. The fault pattern file 139 name is formed in the same way as the fault description file 106 except that the letter `X` is inserted instead of the letter `F`. This file consists of fixed size blocks; each block contains one fault pattern. The index number of a fault pattern is identical to the index number of its corresponding position. The fault diagnosis menu 146 is the focal point for all inferential software 68 activity. On entry to this menu 146, the current failures are abstracted from the exception buffer, not shown, and a new fault pattern is formed, which is matched automatically against all patterns in the database 138. Diagnoses are displayed by group according to the percentage of correlation (figure of merit) between the new fault pattern 139 and each fault in the database 138. Each fault description 116 (FIG. 5) is labeled with its unique fault index. A list of fault diagnosis menu functions appears in Table I, below. Table I. FAULT DIAGNOSIS MENU FUNCTIONS Best Conduct the matching process again in order to display the group of faults which match best. Change Select a specific fault by its index and change the fault description or comment. Delete Select a specific fault and delete it from participation in the matching process. Examine Select a fault and examine the associated error pattern synopsis. Find Find all fault descriptions which match the target string entered by the user. Include Include the new fault pattern under an existing description. List Generate the same display as the Examine function, also sending it to the standard print device. New Add the new error pattern to the database with an associated diagnosis or comment. Options Select Fault Diagnosis Options such as fault type and weight. Query Query the database for matches against a specific fault pattern already in the database. Replace Replace the fault pattern for an existing description with the current fault pattern. Show Next Display the next best group of matching diagnoses. Test Return to the Testing Menu (FIG. 3) 60 and execute the Test function. ESC Return to the Testing Menu (FIG. 3) 60. The figure of merit (FOM) is displayed for each group of faults displayed. This value is a percentage from 0 to 100 which indicates how closely the listed fault patterns match the new fault pattern. A figure of merit of 100% indicates that the listed fault pattern matches the new pattern exactly, whereas 0% indicates that the patterns do not match at all. In order to understand how the figure of merit is calculated, it is helpful to imagine an error plane consisting of "channels" on one axis and "time samples" on the other. All entries are normally binary zero. Each time a discrepant value (i.e., an error) is found, a binary one is placed in the array. The number of channels is arbitrarily 96 and the number of time samples is 2K (i.e., 2048). The contents of each channel is a number (e.g., 2K in the preferred embodiment) of binary data samples representing error information from the UUT collected during a test frame. It is desirable to represent the contents of each channel in several forms, each providing a different way of looking at the data. Three ways of describing this information are by means of BIT, GROUP and RANGE. BIT is a binary word representing the number of errors in the 2K record. GROUP is a binary word representing the number of times the error data goes from "no error" to "error". RANGE includes bits that, when set, represent the case when a segment contains an error. The 2K record is divided into sixty four, 32-bit segments. In the following example, data are placed in groups of eight for simplicity of discussion herein. __________________________________________________________________________00111010 11110000 01010100 00000000 Derived No.__________________________________________________________________________BIT 4 + 4 + 3 + 0 = 11GROUP2 + 1 + 3 + 0 = 6RANGE 1 = 1__________________________________________________________________________ Each of the aforementioned three derived numbers is stored on a per channel basis. The FOM calculation uses the three derived numbers as a basis of its calculations. It is desirable to generate a 1 (100%) if all errors match and a 0 (0%) if no match exists. In normal operation, these numbers are stored for each specific error pattern. Each pattern has an English language message associated therewith. The test is run on a new UUT and the three derived parameters are generated. These parameters are compared with stored fault information in the following way, in which the following terms are defined as shown below. Base Bits=No. of error bits in stored error plane. New Bits=No. of error bits in acquired error plane. Match Bits=No. of error bits in common between Base Bits and New Bits. Using the above-mentioned BIT, GROUP and RANGE numbers independently, the following ratios are calculated. ##EQU1## As can be seen by the foregoing equation, the figure of merit as reported on the monitor represents the weighted average of the different methods. Moreover, other sources of information can be used in this manner, without departing from the scope of the present invention, to contribute to the weighted average. In particular, serial bit streams (as in J-Tag and other boundary scan information) complete data without BIT, RANGE or GROUP calculation. Encoding schemes, including transition encoding, to preserve all information in a compressed form are all valid ways to create a FOM using this technique. Many other ways are possible to accent a way that a UUT might fail in practical situations. Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention.

An adaptive inference system for testing electrical or electronic devices or assemblies. A mechanism is provided for performing position-dependent, time-ordered tests upon electrical or electronic devices in order to obtain a test data array. A mechanism is also provided to define a reference array containing acceptable data for comparison with test data. A comparator is connected to the test data array and to the reference array for providing an error array. An error array library is also provided, which contains accumulated error data. Finally, an error array comparator is connected between the error array library and the error array providing a diagnostic analysis of the electrical or electronic devices or assemblies.

BACKGROUND OF THE INVENTION This invention relates to a printhead and a printing apparatus using the printhead, and more particularly, to a printhead which performs printing in accordance with an ink-jet method and a printing apparatus using the printhead. In ink-jet printing, noise upon printing is very small and negligible, and printing speed is high, further, a print image can be fixed onto a so-called normal paper without special processing. Recently, attention is focused on the ink-jet printing method having these advantages. Among ink-jet printing methods, a printing method disclosed in Japanese Patent Publication Laid-open No. 54-51837 and DOLS No. 2843064, for example, has a feature different from other ink-jet printing methods in that thermal energy is applied to liquid such as ink so as to obtain a driving force for discharging the liquid. That is, according to the above printing method disclosed in these publications, printing is performed by causing a state change with sudden volume increase in the liquid acted upon by the thermal energy, then discharging the liquid from an orifice at the end of a printhead by the action based on the state change, as liquid droplets, and attaching the liquid droplets to a print medium. Especially, according to DOLS No. 2843064, the method is very effectively applied to so-called drop-on-demand printing. Further, the method easily realizes a full-line type printhead having a printing width corresponding to the entire width of a print medium and orifices in a high density. Accordingly, high-resolution and high quality image can be printed at a high speed. The printhead to which the printing method is applied has orifices to discharge liquid, liquid channels, connected to the orifices, each including a heat action portion to supply thermal energy to liquid, and a substrate having electrothermal transducers (heat generators) to generate the thermal energy. Recently, the substrate not only holds the plurality of heat generators but also integrates a plurality of drivers to drive the respective heat generators, a logic circuit including a shift register for temporarily storing image data of number of bits corresponding to the number of heat generators, to transfer the image data serially inputted from a printing apparatus to the respective drivers in parallel, a latch circuit which temporarily latches data outputted from the shift register, and the like. FIG. 16 is a block diagram showing the arrangement of a logic circuit in a conventional printhead having N heat generators (printing elements). In FIG. 16, reference numeral 400 denotes a circuit board; 401 , heat generators; 402 , power transistors; 403 , an N-bit latch circuit; and 404 , an N-bit shift register. Numeral 415 denotes a sensor for monitoring resistance values of the heat generators 401 and the temperature of the circuit board 400 and a heater to maintain the temperature of the circuit board 400 . The sensor may be integrated with the heater, or a plurality of sensors and heaters may be packaged. Numerals 405 to 414 and 416 denote input/output pads. Among these input/output pads, the pad 405 is a clock input pad for inputting a clock (CLK) to operate the shift register 404 ; the pad 406 , an image data input pad for serially inputting image data (DATA); the pad 407 , a latch input pad for inputting a latch clock (LTCLK) to hold image data in the latch circuit 403 ; the pad 408 , a drive signal input pad for inputting a heat pulse (HEAT) to externally control driving period by turning the power transistors 402 ON to energize the heat generators 401 ; the pad 409 , a drive power input pad for inputting a driving power (3-8V; generally 5V) for the logic circuit; the pad 410 , a GND terminal; the pad 411 , a heat generator power input pad for inputting power to drive the heat generators 401 ; the pad 412 , a reset input pad for inputting a reset signal (RST) to initialize the latch circuit 403 and the shift register 404 ; and the pad 413 , an HGND terminal for heat generator drive power source. Further, numerals 414 a and 414 b denote an output pad for outputting a monitor signal and an input pad for inputting control signals for sensor drive and drive of the temperature maintaining heater. Further, numerals 416 -( 1 ) to 416 (n) denote block-selection signal input pads for inputting block selection signals (BLK 1 to BLKn) for block selection in time-division drive. In time-division drive, the N heat generators are divided into n blocks, and driven in block units. Numeral 417 a denotes AND circuits which calculate the logical products of the outputs from the latch circuit 403 and the block selection signals (BLK 1 to BLKn); and 417 b , AND circuits which calculate the logical products of outputs from the AND circuit 417 a and the heat signal (HEAT). Numerals 418 a and 418 b denote parasitic resistances which occur on the wiring used for driving the heat generators 401 . The drive sequence of the printhead having the above construction is as follows. In the following description, image data (DATA) is binary data where 1 bit corresponds to 1 pixel. First, the image data (DATA) is serially outputted from a printing apparatus main body to which the printhead is attached, in synchronization with a clock (CLK), then the data is inputted into the shift register 404 . Next, the image data (DATA) is temporarily stored in the latch circuit 403 , and ON/OFF outputs in correspondence with image data value (“0” or “1”) are made from the latch circuit 403 . In this state, when a heat pulse (HEAT) and a block selection signal are inputted, power transistors supplied with ON outputs from the latch circuit 403 , corresponding to heat generators in a block selected by the block selection signal, are driven for “ON” period of the input heat pulse (HEAT). Then, an electric current flows through the corresponding heat generators. Thus, the print operation is performed. Next, the parasitic resistances 418 a and 418 b will be described. It is preferable that the parasitic resistance does not exist, however, actually it cannot be ignored. The example of FIG. 16 shows the parasitic resistances in the logic circuit of the printhead, however, parasitic resistance also exists on a PCB (printed circuit board) within the printhead or a flexible printer cable (FPC) connecting the printhead and the printing apparatus. In FIG. 16, as the resistances are common to the plurality of heat generators 401 , the ratio between the parasitic resistances and the resistance of all the driven heat generators differs dependent on the number of time-divisionally driven heat generators. As a result, the value of a voltage applied to the heat generators (in other words, the value of voltage drop by the parasitic resistances) changes. Accordingly, the voltage applied to both ends of the heat generators changes due to the duty of a pattern to drive the heat generators, which causes variation in energy to the heat generators. On the other hand, in accordance with the recent tendency of increase in printing speed, a growing number of heat generators are provided in a printhead, and the drive frequency is increasing. In time division drive, the number of simultaneously-driven heat generators is increasing, therefore, the change of voltage drop due to parasitic resistance is not negligible. Conventionally, some methods to prevent voltage drop have been proposed. One of these methods is to feed-back control a heat pulse (HEAT) to drive heat generators, on the printing apparatus side, so as to change the pulse width based on a pattern for driving the heat generators of the printhead. More specifically, as shown in FIG. 17A, on the printing apparatus side, a counter 801 counts the number of simultaneously-driven heat generators based on generated image data, then the counted number is stored into a memory 802 . A drive pulse generator 803 modulates the pulse width based on the number. Otherwise, as shown in FIG. 17B, the counter 801 provided in the printing apparatus counts the number of bits of serially-transferred image data at each time-division drive, and the drive pulse generator 803 controls the pulse width based on the counted number. Further, Japanese Patent Publication Laid-open No. 2-508 discloses a technique to count the number of simultaneously-driven heat generators and to control the pulse width. However, in the conventional art, the shift register and the latch circuit, which have been already provided in the printhead, a circuit to recognize a pattern to drive the heat generators by time-division drive, a counter circuit used for changing the heat pulse width and the like, must be provided on the printing apparatus side. Thus, control on the printing apparatus side is complicated, and the production cost of the apparatus increases. The complexity of control will be described with reference to FIG. 18 . FIG. 18 shows image data of a character “H” represented as a 16×16 matrix with 16 dots in a printhead scanning direction and 16 dots in direction of nozzle array of the printhead. Generally, image data generated in the printing apparatus main body is sequentially transferred in accordance with the order of numbers allotted to the matrix, from “1” to “256”, as shown in FIG. 18 . However, when the above data is transferred to the printhead, the order of data transfer is changed in accordance with the construction of the printhead, and the processed data is transferred. That is, in accordance with the number of nozzles and the printing cycle of the printhead, the order of data transfer is rearranged. As shown in FIG. 18, the transfer order in a case where the number of nozzles of the printhead is “8” is different from that in a case where the number of nozzles is “16”. Further, as described above, the heat generators of the printhead are time-divisionally driven in one printing cycle. Thus, the control is very complicated since factors to be considered include various numbers of nozzles of the printhead, the number of simultaneously-driven blocks, and the number of simultaneously-driven heat generators based on image data, and these factors must be fed back for modulation of the pulse width to drive the printhead. The complicated control will be considered with the examples of FIGS. 17A and 17B. In FIG. 17A, calculation processing is complicated since image data to be subjected to counting dynamically changes in accordance with the construction of the printhead such as the number of nozzles, simultaneously-driven blocks and the like, and the change must be considered in counting processing. On the other hand, in FIG. 17B, as the number of simultaneously-driven heat generators in one printing cycle changes in accordance with the construction of the printhead, the process of transfer image data is complicated. In both cases, the increase in processing load on the printing apparatus main body side cannot be avoided, and in conventional technique nothing could undertake the processing load on the printhead side. Further, although the printhead and the printing apparatus are separable, and they are separately manufactured, further, the printhead is exchangeable, in the controller of the printing apparatus side, not only data interface with respect to the printhead but also the construction of the printhead must be considered. Thus, development and design of printing apparatus have been very troublesome. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a printhead with a comparatively simple construction, which reduces the cost of the entire system and development load, effectively utilizes an essential constituent devices of a logic circuit of a printhead such as a shift register, while omits control on a printing apparatus side, and performs stable print operation by itself, while suppresses variation of energy to heat generators due to voltage drop by parasitic resistance, and a printing apparatus using the printhead. According to one aspect of the present invention, the foregoing object is attained by providing a printhead having plural heat generators, a driver which drives the plural heat generators, and a divider which divides the plural heat generators into plural blocks and time-divisionally drives the plural blocks based on an externally-inputted block selection signal, comprising: a counter which counts the number of simultaneously-driven heat generators based on externally-inputted image data and the block selection signal; and a modulator which modulates a pulse width of a drive signal applied to the simultaneously-driven heat generators based on a value obtained from counting by the counter. Preferably, the modulator has an input pad in which a signal used for modulating the pulse width of the drive signal is inputted. The modulation circuit has various embodiments in accordance with the type of signal inputted into the input pad. That is, in a case where the printhead further comprises a plurality of input pads, and drive signals having different pulse widths are respectively inputted into the plurality of input pads, it is preferable that the modulator includes: (1) a memory for storing a plurality of threshold values; (2) a comparator which compares the plurality of threshold values stored in the memory with the value obtained from counting by the counter; and (3) a selector which selects one of the plurality of drive signals having different pulse widths in accordance with the result of comparison by the comparator. Further, in a case where a clock signal used for inputting the image data is inputted into the input pad, it may be arranged such that the modulator includes: (1) a generator which generates a plurality of drive signals having different pulse widths based on the clock signal; (2) a memory for storing a plurality of threshold values; (3) a comparator which compares the plurality of threshold values stored in the memory with the value obtained from counting by the counter; and (4) a selector which selects one of the plurality of drive signals having different pulse widths generated by the generator, in accordance with the result of comparison by the comparator. Alternatively, the modulator may include: (1) a memory for storing a plurality of threshold values; (2) a comparator which compares the plurality of threshold values stored in the memory with the value obtained from counting by the counter; and (3) a generator which generates a drive signal having an optimum pulse width, based on the clock signal, in accordance with the result of comparison by the comparator. Further, in a case where the printhead further comprises: an N-bit shift register which inputs the image data; an N-bit latch circuit which latches N-bit image data stored in the N-bit shift register; and N AND circuits which obtain logical products of the N-bit image data outputted from the N-bit latch circuit and the block selection signal, the counter counts the number of simultaneously-driven heat generators based on outputs from the N AND circuits. It is preferable that outputs to heat generators which are not simultaneously driven in time-division drive are connected to one of common signal lines, and the common signal lines are connected to the counter. Note that the circuit related to common signal lines has various embodiments. That is, it may be arranged such that (1) the common signal lines are pulled up, and inverters are provided between the common signal lines and the N AND circuits, or (2) the common signal lines are pulled down, and open-drain or open-collector outputs from the N AND circuits are connected to the common signal line, or (3) the common signal lines are pulled down, and amplifiers are provided between the common signal lines and the N AND circuits, further, open-drain or open-collector outputs from the amplifiers are connected to the common signal lines, or (4) the common signal lines are pulled down, and diode switches are provided between the common signal lines and the N AND circuits, further outputs from the diode switches are connected to the common signal lines, or (5) in addition to the construction (4), a bus terminator is connected to an end of each of the common signal lines. Further, the number of common signal lines is equal to or more than a maximum number of heat generators simultaneously-driven in the time-division drive, and less than the number of the heat generators. Further, the counter is preferably an adder, and the adder adds up outputs from the common signal lines. It is preferable that the modulator performs modulation such that when the number of simultaneously-driven heat generators obtained from counting by the counter is larger, the pulse width of the drive signal is wider, while when the number of simultaneously-driven heat generators obtained from counting by the counter is smaller, the pulse width of the drive signal is narrower. Preferably, the printhead is an ink-jet printhead which performs printing by discharging ink. In this case, the printhead has an electrothermal transducer which generates thermal energy to be supplied to the ink, to discharge the ink by utilizing the thermal energy. According to the present invention, the foregoing object is attained by providing a printing apparatus which performs printing by using the printhead having the above construction. In accordance with the printhead of the present invention as described above, the pulse width of a drive signal applied to heat generators is automatically modulated in the printhead in accordance with the number of simultaneously-driven heat generators which always changes based on image data. The invention is particularly advantageous since the variation in energy to the heat generators, due to the number of heat generators driven in the printhead and parasitic resistance of the printhead, can be suppressed, thus stable printing operation can be performed. In this construction, it is not necessary to control the energy to the heat generators so as to reduce the variation in the energy due to parasitic resistance of the printhead on a printing apparatus side, and it is not necessary to provide special circuits on the printing apparatus side. This results in suppressing increase in production cost. Further, as it is not necessary to consider the characteristic of a printhead in development and design of a printing apparatus, the printing apparatus can be developed independently of the printhead. Further, according to the Invention, as the signal used for modulating the pulse width of the drive signal in the modulation circuit is one of drive signals having different pulse widths or a clock signal used for image data input, it is not necessary to generate specific data on the printing apparatus side. Also, it is not necessary to process the specific data on the printhead side. Thus, the pulse width of the drive signal can be modulated with a simple construction. Further, according to the present invention, as signal lines used for counting the number of simultaneously-driven heat generators are commonly used, the area of circuit board can be reduced, thus the printhead can be downsized. Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. FIGS. 1A and 1B are block diagrams showing a portion to count the number of simultaneously-driven heat generators based on image data, and a problem accompanying counting by the part in FIG. 1A; FIGS. 2A and 2B are block diagrams conceptually showing the reduction of the number of count lines; FIG. 3 is a block diagram showing an example of the construction of a circuit which feeds back the number of simultaneously-driven heat generators to heat pulse signal modulation; FIG. 4 is a block diagram showing the relation between a printing apparatus and a printhead according to the present invention; FIG. 5 is a perspective view showing the structure of an ink-jet printer IJRA as a representative embodiment of the present invention; FIG. 6 is a block diagram showing the construction of a controller of the ink-jet printer IJRA; FIG. 7 is a partially-cutaway perspective view showing the internal structure of the printhead mounted on the printer in FIG. 5; FIG. 8 is a block diagram showing the construction of a logic circuit of a printhead IJH; FIG. 9 is a timing chart showing various signals used for printing operation; FIG. 10 is a timing chart showing pulse waveforms of heat enable signals; FIG. 11 is a block diagram showing a first modification in connection with a common use of the count lines; FIG. 12 is a block diagram showing a second modification in connection with a common use of the count lines; FIG. 13 is a block diagram showing a third modification in connection with a common use of the count lines; FIG. 14 is a block diagram showing a fourth modification in connection with a common use of the count lines; FIG. 15 is a block diagram showing a modification of an optimum heat enable signal generator; FIG. 16 is a block diagram showing the construction of the logic circuit of the conventional printhead; FIGS. 17A and 17B are block diagrams showing the relation between the conventional printhead and printing apparatus; and FIG. 18 is an explanatory view showing image data process executed in the conventional printing apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiment of the present invention will now be described in detail in accordance with the accompanying drawings. First, the concept of the present invention will be described. <Concept of Invention> As it is understood from the conventional art, to perform stable printing operation, it is necessary to count the number of simultaneously-driven heat generators based on image data, and feed back the result of counting to drive pulse control, somewhere in a printing apparatus or printhead. FIGS. 1A and 1B are block diagrams showing the portion to count the number of heat generators simultaneously driven based on image data and the problem accompanying the counting. FIG. 1A shows the construction of an AND circuit to drive one heater driver (power transistor). FIG. 1B shows the arrangement of the AND circuits in the printhead. In the present invention, as shown in FIG. 1A, attention is focused on a signal line 1001 , which is turned ON when both image data (DATA) and a block selection signal (BLKi) as a time division signal are ON. The number of ON state signal lines 1001 is counted all over the printhead, and the count value is fed back for modulating a pulsewidth of a heat signal (HEAT). Accordingly, it is unnecessary to temporarily store the number of simultaneously-driven heat generators. This arrangement will be described in detail later. If the above idea is simply applied to manufacturing of circuit board, count lines must be provided corresponding to the number of the heat generators, as shown in FIG. 1 B. However, in a current printhead having 128, 256 or more heat generators, to provide a large number of count lines, a considerably large chip size is required. For example, in a printhead having 128 heat generators, if a width of 4 μm is required for an aluminum (Al) line and insulating space, a chip width of 4×128 μmm≅0.5 mm is required. Accordingly, the simple application of the above idea to board manufacturing results in deficiency in view of downsizing the apparatus and reducing production cost. Accordingly, in addition to the above idea, to reduce the area of the circuit board necessary to provide count lines, the present invention focuses attention on the fact that the maximum number of simultaneously-driven heat generators is the maximum number of heat generators which can be simultaneously driven in each time-division drive and the fact that each count line is turned OFF when time-division drive is not performed, and reduces the number of count lines. FIGS. 2A and 2B are block diagrams conceptually showing the reduction of the number of count lines. FIG. 2A shows the number of count lines which are turned ON in each time-division drive. FIG. 2B shows a construction where the count lines are commonly used, in consideration of the above-described maximum number of count lines which are turned ON upon each time-division drive. As it is understood from FIG. 2A, count lines 1001 a to 1001 c are not turned ON when a time division signal A (BLKA) is not ON, and the maximum number of ON lines is “3”. At this time, all the other count lines not driven by the time division signal A (BLKA) are turned OFF. Similarly, count lines 1001 d and 1001 e can not be turned ON except for a case where a time division signal B (BLKB) is ON, and the maximum number of ON lines is “2”. At this time, all the other count lines not driven by the time division signal B (BLKB) are turned OFF. Accordingly, the number of signal lines necessary to count the number of simultaneously-driven heat generators is the maximum number of heat generators belonging to each time-division section. As shown in FIG. 2B, as a count line belonging to different time-division sections is commonly used for counting in these sections, the number of count lines can be reduced while conflict of ON-state timing can be avoided. As a result, in FIG. 2A, only three count lines 1001 a to 1001 c are used. The commonly-used count lines as above are connected to an adder in the printhead. The adder counts the number of simultaneously-driven heat generators in real time. The result of counting is fed back to heat pulse signal modulation. FIG. 3 is a block diagram showing an example of the construction of a circuit which feeds back the number of simultaneously-driven heat generators to heat pulse signal modulation. In FIG. 3, the adder 104 , connected to the count lines 1001 a to 1001 c commonly used for counting, counts the number of simultaneously-driven heat generators, inputted from these lines, and outputs the result of addition to a heat signal selector 102 a . On the other hand, the heat signal selector 102 a inputs a plurality of heat pulse signals having predetermined different pulse widths. The heat signal selector 102 a selects one of the heat pulse signals in accordance with the result of addition inputted from the adder 104 , and uses the selected heat pulse signal as a drive pulse. When the printhead having the above construction is mounted on a printing apparatus, the relation between the printing apparatus and the printhead is as shown in FIG. 4 . That is, as the printing apparatus simply outputs a plurality of heat pulse signals having predetermined pulse widths generated by the drive pulse generator 803 , a circuit in consideration of the construction of the printhead can be omitted on the printing apparatus side. On the other hand, the printhead selects an appropriate heat pulse signal from the input plurality of heat pulse signals, based on the real-timely counted number of simultaneously-driven heat generators, thus enabling heat pulse width to be controlled independently of the printing apparatus. Hereinbelow, an embodiment to which the above concept of the present invention is applied will be described. First, the structure of a printer carrying a printhead which performs printing according to the present invention will be described. <Outline of Apparatus Main Body> FIG. 5 is a perspective view showing the structure of an ink-jet printer (hereinafter referred to as “printer”) IJRA as a representative embodiment of the present invention. In FIG. 5, a carriage HC is engaged with a spiral groove 5004 of a lead screw 5005 which rotates via drive force transmission gears 5009 to 5011 interlocking with forward/reverse rotation of a drive motor 5013 . The carriage HC has a pin (not shown) and is reciprocated in directions represented by arrows a and b held by a guide rail 5003 . The carriage HC has an ink-jet cartridge IJC which integrally comprises a printhead IJH and an ink tank IT. A paper holding plate 5002 presses a print sheet P against a platen 5000 along the moving direction of the carriage HC. Photocouplers 5007 and 5008 are home position detecting members for confirming the existence of lever 5006 of the carriage in this area and changing over the rotational direction of motor 5013 . A support member 5016 supports a cap member 5022 for capping the front surface of the printhead IJH. A suction member 5015 performs suction-restoration of the printhead through the inside of the cap member 5022 via a cap inner opening 5023 . Member 5019 allows a cleaning blade 5017 to move in a back-and-forth direction. A main body support plate 5018 supports the member 5019 and the cleaning blade 5017 . It is apparent that any well-known cleaning blade is applicable to the printer of the embodiment. Numeral 5021 denotes a lever for starting the suction operation of the suction-restoration. The lever 5021 moves along the movement of a cam 5020 engaged with the carriage HC. A well-known transmission mechanism such as change-over of a clutch controls a drive force from the drive motor. When the carriage HC is at the home position area, a desired one of these capping, cleaning and suction-restoration is executed at its corresponding position by the lead screw 5005 . The timing of any of these processings is not limited to the printer of the embodiment, if a desired processing is performed at a well-known timing. Further, in the ink-jet printer IJRA having the above structure, an automatic sheet feeder (not shown) is provided to automatically feed the print sheet P. <Construction of Controller> Next, the construction of a controller for executing print-control of the above printing apparatus will be described. FIG. 6 is a block diagram showing the construction of a controller of the ink-jet printer IJRA. Referring to FIG. 6 showing the control circuit, reference numeral 1700 denotes an interface for inputting a print signal; 1701 , an MPU; 1702 , a ROM for storing control programs executed by the CPU 1701 ; and 1703 , a DRAM for storing various data (the print signal, print data and the like supplied to the printhead). Reference numeral 1704 denotes a gate array (G. A.) for performing control on print data supply to the printhead IJH. The gate array 1704 also performs data-transfer control among the interface 1700 , the MPU 1701 , and the RAM 1703 . Reference numeral 1710 denotes a carrier motor for transferring the printhead IJH; 1709 , a conveyance motor for conveying the print sheet; 1705 , a head driver for driving the printhead IJH; and 1706 and 1707 , motor drivers for driving the conveyance motor 1709 and the carrier motor 1710 . The operation of the above control arrangement will be described below. When a print signal is input into the interface 1700 , the print signal is converted into print data for a printing operation between the gate array 1704 and the MPU 1701 . The motor drivers 1706 and 1707 are driven, and the printhead IJH is driven in accordance with the print data supplied to the head driver 1705 , thus performing the printing operation. <Internal Structure of Printhead IJH> FIG. 7 is a partially-cutaway perspective view showing the internal structure of the printhead IJH. In FIG. 7, numeral 100 denotes a circuit board holding a logic circuit; 500 , orifices for ink discharge; 501 , ink channels; 502 , a common ink chamber, communicating with the plurality of ink channels, for temporarily storing ink; 503 , an ink supply orifice which supplies ink from an ink tank (not shown); 504 , a top plate; 505 , liquid channel wall members which form the ink channels 501 when assembled with the top plate 504 ; 701 , heat generators; and 507 , wirings connecting the logic circuit to the heat generators 701 . The logic circuit, the heat generators 701 and the wirings 507 are formed by semiconductor manufacturing process on the circuit board 100 . The top plate holding the ink supply orifice 503 and the liquid channel wall members 505 are attached to the circuit board, thus constructing the printhead IJH. Then, ink supplied from the ink supply orifice 503 is stored in the internal common ink chamber 502 and supplied to the respective ink channels 501 . In this state, by driving the heat generators 701 , the ink is discharged from the discharge orifices 500 . <Construction of Logic Circuit of Printhead IJH> FIG. 8 is a block diagram showing the construction of the logic circuit of the printhead IJH. In FIG. 8, constituent elements corresponding to those in the conventional logic circuit in FIG. 16 have the same reference numerals, and explanations of the elements will be omitted. In the above-described concept of the present invention, in time-division drive of the printhead, regarding heat generators driven at different timings, the count line is commonly used. In an actual logic circuit, various circuits are used to input outputs from the count lines into the adder. In the example of FIG. 8, the output from an AND circuit 417 a is inverted by an inverter and pulled up. In FIG. 8, numerals 101 -( 1 ) to 101 -(k) denote input pads for inputting heat enable signals (HTSEL 1 to HTSELk) having different pulse widths supplied from the printer IJRA; 102 , a heat enable selector which selects one of the plurality of heat enable signals (HTSEL 1 to HTSELk); 103 , a comparator which outputs a signal to control the selected heat enable signal from the heat enable selector 102 ; 104 , the adder which adds the number of heat generators simultaneously-driven in time-division drive of the printhead, and outputs the result of addition to the comparator 103 ; and 105 , a memory for storing threshold data for comparison with the output from the adder 104 by the comparator 103 . Numeral 106 denotes m (=N/n) signal lines (count lines) used for determination of the number of simultaneously-driven heat generators; 107 , m pull-up resistors; and 108 , inverters of open-drain (or open-collector) output. The count lines 106 are connected to the adder 104 . As the inverters 108 are provided in correspondence with the respective AND circuits 417 a , N inverters 108 are provided in the logic circuit. The outputs from the inverters 108 are connected to the count lines 106 . As described above, in connection between the inverters 108 and the count lines 106 , the outputs from the AND circuits 417 a selected in the same block by the block selection signal (BLK 2 to BLKn) are not connected to the same count line 106 . By this connection, the maximum count value at the adder 104 is m (=N/n). Further, the respective count lines in the adder 104 are pulled up by the resistors 107 . According to the above construction, as the number of signal lines necessary to count the number of heat generators simultaneously driven by time-division drive and the possible count value can be N/n, the increase in the construction of the logic circuit can be suppressed. Next, drive control of the printhead having the above construction will be described in a case where the number of heat generators is 128 (N=128), the number of time division drive is 8 (n=8), the maximum number of simultaneously-driven heat generators is 16 (m=N/n=128/8), the number of heat enable signals is 4 (k=4), the number of count lines 106 is 16, and the heat enable signals (HTSEL 1 to HTSEL 4 ) are inputted into the input pads 101 -( 1 ) to 101 ( 4 ). Accordingly, in this example, the maximum count value of the adder 104 is “16”. On the other hand, three threshold values are stored in the memory 105 . The comparator 103 compares these threshold values with the count value (CNT) of the adder 104 . If 1≦CNT≦4 holds, the heat enable selector 102 selects the heat enable signal HTSEL 1 ; if 5≦CNT≦8 holds, the heat enable selector 102 selects the heat enable signal HTSEL 2 ; if 9≦CNT≦12 holds, the heat enable selector 102 selects the heat enable signal HTSEL 3 ; and if 13≦CNT≦16 holds, the heat enable selector 102 selects the heat enable signal HTSEL 4 . FIG. 9 is a timing chart showing various control signals used for drive control on the printhead. As is in the case of the conventional art, 128-bit image data (DATA) is inputted into the 128-bit shift register 404 in accordance with the clock (CLK). Further, the image data is stored into the 128-bit latch circuit 403 in accordance with the latch clock (LTCLK). Thereafter, the heat generators are driven based on the latched image data. As shown in FIG. 9, the 128 heat generators are divided into eight blocks each including 16 heat generators, and driven by the block selection signals (BLK 1 to BLK 8 ). In FIG. 9, numerals 1 to 128 are allotted to the 128 heat generators. The heat generators 1 to 16 are selected by the block selection signal BLK 1 ; the heat generators 17 to 32 are selected by the block selection signal BLK 2 ; and the heat generators 113 to 128 are selected by the block selection signal BLK 8 . As an example, FIG. 8 shows the heat generators surrounded by a broken-line, selected by the block selection signal BLK 1 as objects of time-division drive. Next, the four heat enable signals (HTSEL 1 to HTSEL 4 ) having different pulse widths are inputted from the printer IJRA via the input pads 101 -( 1 ) to 101 ( 4 ). As shown in FIG. 9, as the relation among the pulse widths of the heat enable signals, HTSEL 1 <HTSEL 2 <HTSEL 3 <HTSEL 4 holds. The number of heat generators simultaneously driven in each time-divisionally driven block (the number of simultaneously-driven heat generators) is determined based on the image data (DATA) latched by the 128-bit latch circuit 403 . In an example shown in FIG. 9, the numbers in the respective blocks are 2 , 16 , 9 , . . . , 6 . Under these conditions, the adder 104 adds the number of simultaneously-driven heat generators and outputs the result of addition into the comparator 103 . Then, the heat generators selected by the block selection signal BLK 1 are driven with the heat enable signal HTSEL 1 as a heat generator drive signal. The heat generators selected by the block selection signal BLK 2 are driven with the heat enable signal HTSEL 4 as a heat generator drive signal. The heat generators selected by the block selection signal BLK 3 are driven with the heat enable signal HTSEL 3 as a heat generator drive signal. Then, the heat generators selected by the block selection signal BLK 8 are driven with the heat enable signal HTSEL 2 as a heat generator drive signal. In this manner, the greater the number of simultaneously-driven heat generator becomes, the wider the pulse width supplied to the heat generators becomes. If the number of simultaneously-driven heat generators is large, the voltage drop due to the parasitic resistance is large, which reduces the voltage at both ends of the heat generator. To compensate the reduction of actual power supplied to the heat generators due to the voltage drop, the pulse width is increased so as to obtain uniform power. In the above description, specific numbers are employed as the number of heat generators, the number of heat enable signals (referred to as “level number”). Assuming that the pulsewidth of the heat enable signal is wider as the level number is greater, the relation between the simultaneously-driven heat generators and each level is in a general form as shown in Table 1. [TABLE 1] SIMULTANEOUSLY-DRIVEN HEAT LEVEL GENERATORS 1 1 to N/n 2 N/n + 1 to 2N/n . . . . . . i (i − 1) × N/n + 1 to i × N/n . . . . . . k (n − 1)N/n to N Further, as the count lines 106 connected to the adder 104 are pulled up, in data transferred on the count lines 106 , a period required for changing from an active state (“L”) to an inactive state (“H”) is longer than that required for changing from an inactive state (“H”) to an active state (“L”). Accordingly, it is desirable that the pulse waveforms of the heat enable signals have rising edges at the same timing, and have different falling edges, thus having different pulse widths, as shown in FIG. 10 . Assuming that an appropriate pulse width at level 1 is Pw( 1 ), the resistance value of one heat generator is R, and the parasitic resistance value that occurs on wiring related to the heat generator or power transistor is r, the pulse width at an arbitrary level (i) is expressed as follows: Pw ( i )=(2 Xr+R )· Pw ( 1 )/(2 r+R ) X =( i− 1)· N/k ( i<k ). In accordance with the above-described embodiment, a circuit which selects one of a plurality of heat enable signals based on the number of simultaneously-driven heat generators is provided on a logic circuit board of a printhead. In this arrangement, if a printer carrying the printhead simply supplies a plurality of heat enable signals having different pulse widths to the printhead, in the printhead, a heat enable signal having an optimum pulse width is automatically selected in accordance with image data in real time, and printing operation is performed. According to this arrangement, if the number of simultaneously-driven heat generators is small, since the voltage drop due to parasitic resistance is small, a heat enable signal having a relatively narrow pulse width is applied. On the other hand, if the number of simultaneously-driven heat generators is large, since the voltage drop due to parasitic resistance is large, a heat enable signal having a relatively wide pulse width is applied so as to compensate for power loss due to the parasitic resistance. Accordingly, even though the number of simultaneously-driven heat generators changes based on image data, approximately constant energy is supplied to the heat generators. Thus, a stable printing operation can always be performed. Further, this energy uniformization contributes to realization of a long life for the printhead. Further, as the printhead having the above-described construction does not use a clock synchronization circuit for a heat enable signal selection, printing operation is highly tolerant to noise. Furthermore, the circuit for heat enable signal selection can be formed in a layer under the wiring of the heat generators and power transistors and the like, of the logic circuit board, which conventionally has not been fully utilized for prevention of erroneous operation, together with these devices, by a semiconductor manufacturing process. In this case, the chip size is not substantially different from the conventional chip size. Further, the selection of heat enable signal having an optimum pulse width can be automatically performed within the printhead. In other words, the printing apparatus side does not have to be involved in the selection. The printing apparatus side simply transmits a plurality of heat enable signals having different widths to the printhead. Thus, it is not necessary for the printing apparatus to perform various control in accordance with the construction of the printhead as pointed out in the conventional techniques. Accordingly, the printing apparatus and the printhead can be designed and manufactured independently of each other except for matching between respective signal interfaces, and factors considered in design can be reduced. Note that in the above description, the number of heat generators is 128; however, the present invention is not limited to this number. The number of heat generators may be 256 or 512, for example. <Various Modifications in Connection with a Common Use of Count Lines> In the construction as shown in FIG. 8, the inverters 108 are provided between the AND circuits 417 a and the count lines 106 , and the count lines are pulled up, however, the present invention is not limited to this arrangement, but various modifications can be made. Hereinbelow, some of these modifications will be described. (1) First Modification FIG. 11 is a block diagram showing a first modification. In FIG. 11, the open-drain or open-collector output from the AND circuit 417 a is directly connected to the count line 106 , and the count line 106 is connected the ground by using a pull-down resistor 107 ′, thus pulled down. (2) Second Modification FIG. 12 is a block diagram showing a second modification. In FIG. 12, the output from the AND circuit 417 a is amplified via an OP amplifier 109 , and open-drain or open-collector output from the OP amplifier 109 is directly connected to the count line 106 . The count line 106 is connected to the ground, by using the pull-down resistor 107 ′, thus pulled down. In this arrangement, as an amplified signal is outputted onto the count line 106 , the voltage drop can be suppressed in a case where the distance from the contact of the count line 106 to the adder is long. (3) Third Modification FIG. 13 is a block diagram showing a third modification. In FIG. 13, the output from the AND circuit 417 a is directly connected to the count line 106 via a switch 110 comprising a diode or the like, and the count line 106 is connected to the ground by using the pull-down resistor 107 ′, thus pulled down. This arrangement prevents entrance of signal outputted onto the count line 106 from another AND circuit 417 a in an opposite direction by setting a threshold value of the switch 110 to a predetermined voltage value. (4) Fourth Modification FIG. 14 is a block diagram showing a fourth modification. In FIG. 14 having the same construction as that of FIG. 13, a bus terminator 111 is added to the end of the count line 106 so as to improve the drive performance with respect to the count line 106 . <Modification of Optimum Heat Enable Signal Generator> In the above-described embodiment, a plurality of heat enable signals having different pulse widths are inputted, and a heat enable signal having an optimum pulse width is selected, however, the present invention is not limited to this arrangement, but various modifications can be provided. That is, in place of the construction to input a plurality of heat enable signals and select one of these signals, a circuit which inputs a clock (CLK) used for image data (DATA) transfer and generates a plurality of heat pulse signals having different pulse widths based on the clock (CLK) may be provided in the printhead. Then, as described above, the comparator 103 compares the result of addition by the adder 104 with the threshold data stored in the memory 105 , and a heat enable signal having an optimum pulse width can be selected from the generated signals, based on the result of comparison. In this arrangement, as the pads for inputting the plurality of heat enable signals are omitted, the area of the circuit board can be reduced, thus the printhead circuit board can be downsized. Alternatively, as shown in FIG. 15, the printhead may have a heat signal generator 102 ′ which inputs the clock (CLK) used for image data (DATA) transfer and directly generates a heat enable signal having an optimum pulse width based on the clock (CLK) and the result of comparison by the comparator 103 between the result of addition by the adder 104 and the threshold data stored in the memory 105 . In the above-described embodiment, the printhead performs printing in accordance with an ink-jet method, however, the present invention is not limited to this printhead. The present invention is applicable to a printhead which performs printing in accordance with e.g. a thermal-transfer method or thermal printing method. However, the present invention can attain a high-density, high-precision printing operation by employing an ink-jet printer, which comprises means (e.g., an electrothermal transducer, laser beam generator, and the like) for generating heat energy as energy utilized upon execution of ink discharge, and causes a change in state of an ink by the heat energy, among the ink-jet printers. As the typical arrangement and principle of the ink-jet printing system, one practiced by use of the basic principle disclosed in, for example, U.S. Pat. Nos. 4,723,129 and 4,740,796 is preferable. The above system is applicable to either one of the so-called on-demand type or a continuous type. Particularly, in the case of the on-demand type, the system is effective because, by applying at least one drive signal, which corresponds to printing information and gives a rapid temperature rise exceeding nucleate boiling, to each of electrothermal transducers arranged in correspondence with a sheet or liquid channels holding a liquid (ink), heat energy is generated by the electrothermal transducer to effect film boiling on the heat acting surface of the printhead, and consequently, a bubble can be formed in the liquid (ink) in one-to-one correspondence with the drive signal. By discharging the liquid (ink) through a discharge opening by growth and shrinkage of the bubble, at least one droplet is formed. If the drive signal is applied as a pulse signal, the growth and shrinkage of the bubble can be attained instantly and adequately to achieve discharge of the liquid (ink) with the particularly high response characteristics. As the pulse drive signal, signals disclosed in U.S. Pat. Nos. 4,463,359 and 4,345,262 are suitable. Note that further excellent printing can be performed by using the conditions described in U.S. Pat. No. 4,313,124 of the invention which relates to the temperature rise rate of the heat acting surface. As an arrangement of the printhead, in addition to the arrangement as a combination of discharge nozzles, liquid channels, and electrothermal transducers (linear liquid channels or right angle liquid channels) as disclosed in the above specifications, the arrangement using U.S. Pat. Nos. 4,558,333 and 4,459,600, which disclose the arrangement having a heat acting portion arranged in a flexed region is also included in the present invention. In addition, the present invention can be effectively applied to an arrangement based on Japanese Patent Publication Laid-Open No. 59-123670 which discloses the arrangement using a slot common to a plurality of electrothermal transducers as a discharge portion of the electrothermal transducers, or Japanese Patent Publication Laid-Open No. 59-138461 which discloses the arrangement having an opening for absorbing a pressure wave of heat energy in correspondence with a discharge portion. Furthermore, as a full line type printhead having a length corresponding to the width of a maximum printing medium which can be printed by the printer, either the arrangement which satisfies the full-line length by combining a plurality of printheads as disclosed in the above specification or the arrangement as a single printhead obtained by forming printheads integrally can be used. In addition, an exchangeable chip type printhead which can be electrically connected to the apparatus main unit and can receive an ink from the apparatus main unit upon being mounted on the apparatus main unit can be applicable to the present invention as well as a cartridge type printhead in which an ink tank is integrally arranged on the printhead itself, as described in the above embodiment. It is preferable to add recovery means for the rinthead, preliminary auxiliary means and the like to the above-described construction of the printer of the present invention since the printing operation can be further stabilized. Examples of such means include, for the printhead, capping means, cleaning means, pressurization or suction means, and preliminary heating means using electrothermal transducers, another heating element, or a combination thereof. It is also effective for stable printing to provide a preliminary discharge mode which performs discharge independently of printing. Furthermore, as a printing mode of the printer, not only a printing mode using only a primary color such as black or the like, but also at least one of a multi-color mode using a plurality of different colors or a full-color mode achieved by color mixing can be implemented in the printer either by using an integrated printhead or by combining a plurality of printheads. Moreover, in each of the above-mentioned embodiments of the present invention, it is assumed that the ink is a liquid. Alternatively, the present invention may employ an ink which is solid at room temperature or less and softens or liquefies at room temperature, or an ink which liquefies upon application of a use printing signal, since it is general practice to perform temperature control of the ink itself within a range from 30° C. to 70° in the ink-jet system, so that the ink viscosity can fall within a stable discharge range. In addition, in order to prevent a temperature rise caused by heat energy by positively utilizing it as energy for causing a change in state of the ink from a solid state to a liquid state, or to prevent evaporation of the ink, an ink which is solid in a non-use state and liquefies upon heating may be used. In any case, an ink which liquefies upon application of heat energy according to a printing signal and is discharged in a liquid state, an ink which begins to solidify when it reaches a printing medium, or the like, is applicable to the present invention. In this case, an ink may be situated opposite electrothermal transducers while being held in a liquid or solid state in recess portions of a porous sheet or through-holes, as described in Japanese Patent Publication Laid-Open No. 54-56847 or 60-71260. In the present invention, the above-mentioned film boiling system is most effective for the above-mentioned inks. In addition, the ink-jet printer of the present invention may be used in the form of a copying machine combined with a reader and the like, or a facsimile apparatus having a transmission/reception function in addition to an image output terminal of an information processing apparatus such as a computer. The present invention can be applied to a system constituted by a plurality of devices (e.g., a host computer, an interface, a reader and a printer) or to an apparatus comprising a single device (e.g., a copying machine or a facsimile apparatus). As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

A printhead with a comparatively simple construction, which contributes to reducing the cost of the entire system and development work, effectively utilizes essential constituent devices of a logic circuit of the printhead such as a shift register, while omitting control on the printing apparatus side, and individually performs stable print operation, while suppressing variation of energy inputted to heat generators due to voltage drop by parasitic resistance. A printing apparatus incorporates the printhead. The printhead has a counter which counts the number of simultaneously-driven heat generators, which always changes in accordance with image data, based on externally-inputted image data and block selection signal, and a modulator which modulates the pulse width of a drive signal applied to the simultaneously-driven heat generators based on a value obtained from counting by the counter.

BACKGROUND OF THE INVENTION The present invention relates to automobile security equipment, particularly to anti-theft devices for automobiles. The prior art includes various security devices for automobiles which effectively disable the steering wheel by preventing its turning. Such prior steering wheel disabling devices may be divided into two general classes. The first includes steering wheel locking devices which comprise steering column interlocking or engaging components. Such prior devices are typically mechanically or electro-mechanically interconnected to the automobile ignition locking system. The second general classification of prior steering wheel locking devices includes those devices which comprise removable mechanical steering wheel engaging elements which come into movement-limiting contact with a fixed member of the automobile. The present invention is of the latter general classification of steering wheel locking devices. Chen (U.S. Pat. No. 5,199,283) discloses an automobile steering lock which, in many ways, is typical of prior removable steering wheel-engaging security devices. The Chen device is popularly known and marked under the trade name "THE CLUB". Although these prior devices are advertised to prevent or deter automobile theft, such devices have several short-comings and, in many cases, have failed in this endeavor. Most prior removable steering wheel-engaging security devices, such as the Chen device, comprise a rigid elongated portion and locking means for temporarily securing the rigid elongated portion to the steering wheel. The locking portion typically involves a lock and key set, and openable jaws which are adapted to engage the rim of the steering wheel. The rigid elongated portion typically comprises a hard metallic bar, or the like, which extends well beyond the rim of the steering wheel. When properly installed (i.e. locked into place) onto the rim of a steering wheel, the elongated bar prevents full and safe rotation of the steering wheel because, depending upon the design of the elongated portion and the make of the automobile, the elongated bar comes into a fixed member of the automobile (eg. the window, the door, the dash board, the windshield, etc.). Clearly, proper operation of such prior devices depends on (1) the adequacy of the locking portion to tightly secure to the steering wheel rim, and (2) the strength of the elongated portion. Accordingly, such prior devices typically have over-designed, excessively strong locks, and have elongated portions constructed of excessively strong metal or composite materials. Largely overlooked with prior removable steering wheel-engaging security devices is that, in order to defeat or bypass such devices, it is only necessary to cut (i.e. saw) the steering wheel rim at the point of attachment to the locking member. For example, in order to defeat the elongated steering wheel locking device of Chen (U.S. Pat. No. 5,199,283) it is only necessary to make one (or, at the most, two) small cuts in the rim of the steering wheel. Once the rim of the steering wheel is cut, the locking device is quite easily removed and the automobile can readily be steered. It will be appreciated by those skilled in the art that such prior removable steering wheel-engaging security devices can be defeated in such a manner, totally independent of the strength of lock or the hardness of the elongated portion. SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide a removable steering wheel-engaging security device which significantly and materially lessens the probability of the theft of an automobile. Another object of the present invention is to provide a device of the character described which is easily visible from the exterior of a vehicle, and which may deter a potential thief from attempting to steal the vehicle equipped with this invention on its steering wheel. Yet another object of the invention is to provide an apparatus of the character described that is not cumbersome, easy to use, and is inexpensive in relation to its benefits. Another object of the present invention is to provide a removable steering wheel-engaging security device which provides greater anti-theft deterrence than prior devices, by preventing physical access to a steering wheel surface. Another object of the present invention is to provide a removable steering wheel-engaging security device which prevents the removal of the device and protects the steering wheel from cutting, by way of hack saw, by denying a thief access to the surface of the steering wheel. Another object of the present invention is to provide a removable steering wheel-engaging security device which provides a simple detachable device which is easily carried and stored within the vehicle and is easy to manufacture. These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being made to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view of the present invention shown installed on an automobile steering wheel; FIG. 2 is a plan view of one form of the invention as shown in FIG. 1; FIG. 3 is a side view of the security rod hook flanges located on the side apron of the invention; FIG. 4 is front elevation of the present invention shown installed on an automobile steering wheel; FIG. 5 is a top view of the present invention installed on an automobile steering wheel, shown in partial cross-section; FIG. 6 is a side view of the invention as placed in its fixed position on a steering wheel; and FIG. 7 shows the present invention mounted on a steering wheel of an automobile. DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 through 6, there is shown a rigid metal housing, or "shield" (generally designated (50) in the drawings), having a shield body (22) which is positioned in front of, and encompasses, the surface of a steering wheel (W), and a side apron (14) which extends around the side of the steering wheel (W). The shield body (22) has a predetermined configured opening (32) which is designed to allow manual access to a tubular security rod member (26) for placement on the steering wheel (W) and to facilitate adjustment of the telescopic security rod member (30). The shield opening (32) can be shaped, or configured to accommodate any style steering wheel, including, but not limited to, flat to convex configurations to accommodate any steering wheel configuration, including, but not limited to steering wheels with airbags. A pair of security rod hump housings (24) are integrally formed on the shield body (22). The security rod hump housings are located at diametrically opposed positions on the face of the shield body (22). An adjustable telescopic security rod member (48) extends through both hump housings (24) and traverses the center of the shield body (22). The telescopic security rod member (48) comprises a first telescopic security rod member (30) telescopically engaged with a second tubular security rod member (26). Each telescopic security rod member extends through one of the hump housings. The adjustable security rod member (48) is immovable, and neither the telescopic security rod member (30) nor the tubular security rod member (26) can be removed or separated from their respective hump housings (24). The tubular security rod member (26) and the telescopic security rod member (30) have single welded steel security rod hooks (10) connected and attached at the diametrically opposed ends of the shield security rod members (26) and (30), respectively. A hand grip 40 is installed on the free end of the telescopic security rod member (30). The telescopic security rod member 30, when extended to its maximum position on the steering wheel (W), allows the diametrically opposed security rod hooks (10) to snugly engage under the bottom, or under-surface of the steering wheel (W). The security rod hooks (10) will then insert themselves into the hook flange catches (12) which are located at diametrically opposed positions on the shield body's side apron (14). The telescopic security rod member (48) may be optimally extended on the steering wheel (W), by manually gripping the knurled hand grip (42) on the tubular security rod member (26), which is longitudinally connected to the telescopic security rod member (30) as shown in FIG. 6. The telescopic security rod member (48) will automatically lock in place by means of any well known locking mechanism (36) for locking a pair of telescoping tubular rods. In the preferred embodiment of the invention the telescopic security rod member (30) is long enough that, in operation, it extends sufficiently outboard of the rim of the steering wheel (W) to come into contact with a fixed member of the automobile (such as the door, or the dashboard, or the floor, or the windshield, etc.) when the steering wheel is turned. The locking mechanism (36) can be configured and placed in any appropriate location on either the tubular security rod member (26) or on the telescopic security rod member (30). The shield body (22) and its apron (14) are preferably constructed of a rigid metal, (such as steel), since the strength of this device is of paramount importance. It will be understood from the foregoing description that a device constructed in accordance with the present invention provides a rigid metal anti-theft shield body (22) having an accurately contoured apron (14) with two diametrically opposed welded, or fixed hook flange catches (12), which, when placed on a steering wheel (W) completely covers the surface, rim, and periphery of the steering wheel. The telescopic security rod member (30) and the tubular security rod member (26) together provide an immovable, albeit adjustable, security rod which together are designated as (48) in the drawings. This encased, immovable, adjustable steel security rod (48) traverses horizontally through the center of the shield body (22), and same is encased within security rod hump housings (24) that are designed to allow longitudinal (i.e. axial) telescopic movement of the telescopic security rod member (30). The security rod (48) is connected to the steering wheel (W) by single welded steel hooks (10), which are attached at diametrically opposed ends of the security rod (48). A configured access, or opening (32) in the center surface face of the shield body (22) is designed to allow manual access to the security rod (48) for its placement on the steering wheel (W), and to telescopically extend the hooks (10) into the shield body's hook flange catches (12). A mesh surface (42) is provided on the security rod (48) to facilitate manual gripping of the security rod. Once fully extended, the diametrically opposed hooks (10) on the security rod (48) engage snugly under the bottom surface of the steering wheel (W), and then are inserted into the hook flange catches (12) located on the shield body's side apron (14), by telescopically extending the security rod (48) which automatically engages the security rod locking mechanism (36) after extending to its maximum position on the steering wheel (W). Once the shield (50) is securely fixed on the steering wheel (W), it will be readily apparent to any potential automobile thief that the vehicle will be too difficult, and, more importantly, too time consuming to attempt a theft of the vehicle, or to remove the shield (50) to gain access to the steering wheel in order to operate the vehicle. In particular, because the shield 50 completely surrounds the front and side of the steering wheel, it would be readily apparent to any potential automobile thief that the security device made in accordance with the present invention could not be removed from the steering wheel, for example, by simply making one or two saw cuts through the steering wheel's rim. Although the description above contains the material specification of the invention, these should not be construed as limiting the scope of the invention, but as merely providing illustrations of the presently preferred embodiment of the invention. For example, the shield body (22) can be of several shapes other than circular, such as square, oval, concave, etc., the shield body's hook flanges located on the shield body's side apron (14), which engage the telescopic security rod hooks can have other shapes and locations on the shield body's side apron (14), and can be more than two as specified in the present invention, the shield body's aperture, or opening (32), can be any shape, or configuration, such as circular, oval, trapezoidal, square, rectangular, etc., to accommodate a particular steering wheel design; the metal shield (50) can be constructed of any rigid metal or combination metal/fiberglass composition, or other materials to provide the necessary body strength of the shield body (22) and the shield body's side apron (14). Additionally, the security rod hump housings (24) may be of any configuration, such as square, round or concave, etc., and can be either flush with the surface of the shield body (22), or encased in any depth within said shield body, consistent with the operation and adjustment of the telescopic security rod. Further, the number of security rod hooks, and their shape, or configuration, and the location, or position of the hooks on the telescopic security rod may vary in the invention. The telescopic security rod shape can be round, square or of any specified length, weight or predetermined configuration consistent with the hump housings (24) which will accommodate the adjustment of the telescopic security rod (30), and which will secure the shield 50 to a steering wheel (W). In addition, the locking means mechanism on the invention's telescopic security rod can be of any size, means or location on the security rod, or on the shield body, or a combination of both, consistent with the intended purpose of the invention to secure and fix the housing enclosure to a steering wheel, and to render the steering wheel unaccessible. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and, accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. Accordingly, the scope of the invention should be determined not by the embodiment illustrated, but by the appended claims and their legal equivalents.

An anti-theft device for attachment to a steering wheel of an automobile, has a continuous metal shield, having a shield body which is accurately shaped to completely cover the top surface of the steering wheel and a shield body's side apron which is accurately shaped to completely surround the outer periphery of the steering wheel. The metal shield is configured to encase an elongate rigid security rod in diametrically opposed hump housings located on the face of the shield body. A pair of opposing hooks engage the rim of the steering wheel when the elongate rigid security rod is telescopically extended. Hook flanges extending from the underside of the shield body's apron engage the two hooks. A keyed lock secures the device to the steering wheel. Access to the keyed lock is provided by an access opening in the center of the shield body.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image-forming optical system used for a projection type image display apparatus such as a projector and an image pickup apparatus such as a camera. 2. Description of the Related Art A projection type image display apparatus displays an image by illuminating an image display element such as a liquid crystal panel or digital micro mirror device with luminous flux from a light source and enlarging/projecting transmitted light or reflected light modulated by the image display element on a screen, etc. using a projection lens. FIG. 4 shows a projection optical system disclosed in International Publication No. WO97/01787, which relates to patents to be republished. In this optical system, luminous flux emitted from a light source 101 a is reflected by reflection mirrors such as illumination optical systems 101 b , 101 c and 101 d and incident upon a reflection type image display panel 102 . Then, the luminous flux modulated and reflected by the image display panel 102 is reflected by mirrors 103 a , 103 b , 103 d , 103 e and a flat mirror 103 f which are capable of image-forming, and diagonally projected onto a screen 104 . On the other hand, various image-forming optical systems using a decentered optical system aiming at miniaturization of the entire optical system have been recently proposed. A decentered optical system introduces a concept called a “reference optical axis” and can construct an optical system with aberration sufficiently corrected by forming a rotationally asymmetric aspherical surface or so-called free form surface. For example, Japanese Patent Laid-Open No. 9-5650 proposes the design method and Japanese Patent Laid-Open No. 8-292371 and Japanese Patent Laid-Open No. 8-292372 propose design examples thereof. When an off-axial optical system, that is, a reference optical axis along the ray penetrating the center of an object (or the center of an image) and the center of the pupil is considered, this decentered optical system is defined as an optical system including an off-axial curved surface where the plane normal at the intersection with the reference optical axis of the configured surface is not on the optical axis and is referred to as an optical system with a folded reference optical axis. This optical system, by appropriately configuring, prevents eclipse even on the reflecting surfaces, and therefore it is easier to construct an optical system using the reflecting surfaces. The off-axial optical system also features the ability to route optical paths relatively freely. Furthermore, using a reflection image-forming optical system only using surface curved mirrors makes it possible to remove almost all influences of chromatic aberration which is a problem of a refractor system. In a projection optical system disclosed in International Publication No. WO97/01787 shown in FIG. 4 , reflectors 103 a , 103 b , 103 d and 103 e having image-forming action in particular are constructed of rotationally symmetric aspherical reflectors having a common rotation axis and images are diagonally projected using the reflectors of these concave mirrors and convex mirrors partially. However, there are restrictions on the degree of freedom, such that the surfaces should have a common axis, and therefore there are limitations to correcting aberration and brightening the reflection optical system (reducing the F number). Furthermore, according to this projection optical system, luminous flux that has passed through an aperture-stop 103 c is incident upon a convex mirror 103 b and the divergent luminous flux from this convex mirror 103 b is incident upon the next convex mirror 103 d . For this reason, the effective diameter of the convex mirror 103 d has a tendency to increase. In this way, the distance between the reflectors of the projection image-forming optical system constructed by combining a plurality of mirrors tends to increase and the problem is that the size of the entire apparatus increases. With regard to an image projection apparatus, a projection apparatus generally uses a transmission type liquid crystals for the image display panel. Furthermore, as an image-forming optical system used for the projection apparatus, almost all products use refraction lenses under actual circumstances. In the image-forming optical system used with this transmission type liquid crystal panel device, it is well known that the object, which is the image display panel, needs to have a telecentric optical configuration in order to improve light utilization efficiency. Though it depends on the specification of the product, the projection image-forming optical system is generally required to be brighter than F3.0 in order to reduce the load on the illumination optical system, reduce costs and power consumption and provide optimal apparatus performance. When an image-forming optical system constructed by combining a plurality of curved reflection mirrors is used instead of a projection image-forming system using refraction lenses, the off-axial optical system is characterized in that the off-axial optical system can set the projection angle (projection angle of elevation) high (large) more easily than the refraction optical system. However, designing the refraction optical system with high projection angles requires an extremely wide angle of view, which results in a problem that the design becomes more difficult and the diameter of lenses increases. Constructing an optical system by only combining surface reflection mirrors with a hollow configuration per se has an advantage of preventing influences of chromatic aberration, etc. However, attempting to apply an image-forming optical system combining curved reflection mirrors as the projection image-forming optical system meeting requirements of the projection apparatus using the above-described liquid crystal panel involves the following problems. In the case of a lens, which is brighter than F3.0 on the image display panel side, it is unavoidable that the effective diameter of the first mirror on the object side increases. Furthermore, as described above, since the object side is telecentric, points from which spread luminous flux is emitted in the direction perpendicular to the surface of the object are arranged side by side with the height of the object corresponding to the size of the image display panel as object points, and the effective diameter of the first mirror unavoidably increases all the more. This results in a problem that the size of the entire optical system increases. SUMMARY OF THE INVENTION It is an object of the present invention to provide a compact image-forming optical system used for a projection type image display apparatus and image pickup apparatus capable of projecting at a high angle of elevation when used, for example, for a projection type image display apparatus and also brightening the F number. In order to attain the above-described object, an image-forming optical system of the present invention, provided with a plurality of curved mirrors whereby two points at different distances are made to have an optically conjugate relationship, when an optical path is traced from a first conjugate point which is nearer to a second conjugate point which is farther, in order starting with the first conjugate point, comprises the following elements. That is, the image-forming optical system comprises a first mirror which reflects luminous flux from the first conjugate point to transform the luminous flux into substantially parallel luminous flux, and a second mirror which reflects the luminous flux reflected by the first mirror while keeping the luminous flux substantially parallel. Then, the following condition should be satisfied: |Arctan(1/2 F )−|2×(ξ−η)||≦10[deg]  (1) where ξ is an absolute value of an angle formed by the normal line of the first mirror and a reference axis at an intersection of the reference axis and the first mirror, the reference axis is an optical path along which a central ray of the luminous flux from the first conjugate point progresses, η is an absolute value of an angle formed by the normal line of the second mirror and the reference axis at an intersection of the reference axis and the second mirror, and F is an effective F number on the first conjugate point side. Furthermore, an image-forming optical system of the present invention, provided with a plurality of curved mirrors whereby two points at different distances are made to have an optically conjugate relationship, when an optical path is traced from a first conjugate point which is nearer to a second conjugate point which is farther, in order starting with the first conjugate point, comprises the following elements. That is, the image-forming optical system comprises a first mirror which reflects luminous flux from the first conjugate point to transform the luminous flux into substantially parallel luminous flux and a second mirror which reflects the luminous flux reflected by the first mirror while keeping the luminous flux substantially parallel. Then, the following condition should be satisfied: 2.3≧2 ×L 1 ×sin η/Φ 1 ≧1.1  (2) Φ 1 = L 0 ′/ F+P   (3) where P is a size of a conjugate surface which has a predetermined size and includes the first conjugate point within the meridional cross section, the meridional cross section is a flat plane including a reference axis which has been folded by the first and second mirrors, the reference axis is an optical path along which a central ray of the luminous flux from the first conjugate point progresses, F is an effective F number on the first conjugate point side, L 0 ′ is an air equivalent distance along the reference axis from the first conjugate point to the first mirror, L 1 is an air equivalent distance along the reference axis from the first mirror to the second mirror and η is an absolute value of an angle formed by the normal of the second mirror and the reference axis at an intersection of the reference axis and the second mirror. Furthermore, an image-forming optical system of the present invention for sequentially reflecting and projecting luminous fluxes which are modulated by a display element using a plurality of curved mirrors, comprises the following elements. That is, an image-forming optical system comprises a first to final (k)th mirrors provided as the above-described plurality of curved mirrors, in the order in which luminous flux progresses from the display element side. Then, the (k−1)th, (k−2)th and (k−3)th mirrors are given positive, negative and positive power, respectively and the (k)th mirror is given positive power. Furthermore, an image-forming optical system of the present invention for sequentially reflecting and projecting luminous fluxes which are modulated by a display element using a plurality of curved mirrors, comprises the following elements. That is, an image-forming optical system comprises a first to final (k)th mirrors are provided as the above-described plurality of curved mirrors in the order in which luminous flux progresses from the display element side. Then, when a reference axis is an optical path along which a central light ray of the luminous flux from the display element progresses and distances along the reference axis from the (k−1)th and (k−2)th curved mirrors to the next (k)th and (k−1)th curved mirrors are L(k−1) and L(k−2), respectively, the following condition should be satisfied. L ( k −1)> L ( k −2)  (4) A detailed configuration of the image-forming optical system, projection type image display apparatus and image pickup apparatus of the invention, the above and other objects and features of the invention will be apparent from the embodiments, described below. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a detailed block diagram of a projection optical system of a projection type image display apparatus according to an embodiment of the present invention; FIG. 2 is an overall block diagram of the projection optical system of the projection type image display apparatus shown in FIG. 1 ; FIG. 3 is a block diagram of an image pickup apparatus according to another embodiment of the present invention; and FIG. 4 is a block diagram of a conventional projection optical system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings. Before explaining embodiments of the present invention, the way of presenting the configuration specifications in the embodiments and elements common to all the embodiments will be explained. The embodiments of the present invention will explain the case where an image-forming optical system of the present invention is mainly used as the projection optical system. In this case, the first conjugate point which is nearer corresponds to a point on an image display element and the second conjugate point which is farther corresponds to a point on a screen (a point on an image pickup medium such as an image pickup element corresponds to the first conjugate point and a point on an object corresponds to the second conjugate point in the case of an image pickup optical system). Then, each reflecting surface making up the optical system is determined in such a way that the (m)th surface in the order in which light progressing from the first conjugate point side (image display element side) to the surface of the image on the second conjugate point side (screen or projection surface side) arrives is expressed as the “(m)th surface”. In the case of the projection optical system, the image display element corresponds to the object and the projection surface (screen) corresponds to the surface of the image. Each reflecting surface is a surface mirror made up of a surface form molded with plastics, etc. coated with a reflection coating, etc. and the medium that fills the space between mirrors is air. Thus, all the embodiments are so-called hollow type optical systems. By the way, since it is possible to give an aspheric surface power component with a diffraction grating to the surface of a spherical surface mirror by shaping at least one of the reflecting surfaces like a diffraction grating, the shape of the base mirror can be simplified in comparison with an aspheric surface (shaped) reflector. Furthermore, by forming a plurality of free form surfaces on the back surface of a bulk of glass or plastic and forming a reflecting coating on them to use at least one reflecting surface as a backside mirror, it is also possible to provide a configuration whereby luminous flux progresses inside the bulk medium. In order to explain the embodiments, three items; a reference axis, a global coordinate system and a local coordinate system, will be defined first. Since the optical system according to the embodiments of the present invention is an off-axial optical system, the optical surfaces making up the optical system do not have a common optical axis. In the embodiments of the present invention, light emitted from the center of the image display element which is an object in the direction perpendicular to this image display element is a reference, and this light ray is regarded as a reference light ray. Then, the optical path along which this reference light ray progresses, that is, the optical path along which the central light ray of the luminous flux progresses from the first conjugate point is regarded as a reference axis. The reference axis has directivity (orientation). The direction of the reference axis is the one in which the reference light ray progresses to form an image. The reference axis finally reaches the center of the surface of the image while changing the direction along the set sequence of surfaces according to the law of reflection. Then, a global coordinate system (global coordinates are expressed by capital letters XYZ) with the center of the surface of the object which is the image display element as the origin will be considered. The axes of the global coordinate system will be defined as follows. Suppose the coordinate system is a right-hand system. {circle around (1)} Z-axis: A straight line which passes through the global origin and is perpendicular to the surface of the object. The direction from the surface of the object to the first mirror is considered positive. {circle around (2)} Y-axis: A straight line which passes through the global origin and forms 90° counterclockwise with respect to the Z-axis. This embodiment assumes that the above-described reference axis exists within the YZ plane. Therefore, all the curved mirrors making up the reflection image-forming optical system of each embodiment are tilted within the YZ plane. Furthermore, a meridional cross section coincides with the YZ plane. Furthermore, in the drawings of the respective embodiments, the plane of the sheet coincides with the YZ plane. The orientation of the sign of the Y-axis is arbitrary. However, in the embodiments, the direction in which the reference axis is reflected and progresses by each mirror is considered positive. Therefore, the positive direction of the Y-axis in the drawing of each embodiment is upward in the drawing. {circle around (3)} X-axis: A straight line which passes through the origin and is perpendicular to the Z-axis and Y-axis (straight line perpendicular to the plane of the sheet in each drawing). Since it is the right-hand system, the direction toward the back of the sheet is positive. When expressing the shape of the (m)th surface making up the optical system, setting a local coordinate system (local coordinate system is expressed with small letters xyz) corresponding to each surface by regarding each point advanced by the distance between surfaces on the reference axis as a local origin is easier to understand the shape of each of surfaces, than expressing the shapes of the surfaces in a global coordinate system, and therefore the shape of the (m)th surface is expressed in a local coordinate system (right-hand system). Furthermore, suppose tilting of a surface is also expressed by tilting the local coordinate system corresponding to each surface. The tilt angle within the YZ plane of the local coordinate system corresponding to the (m)th surface is expressed with an angle θm (unit is °, which will be omitted hereafter) with the counterclockwise direction with respect to the Z-axis of the global coordinate system considered positive. Thus, all the origins of the local coordinates of the respective surfaces in the embodiments are naturally on the YZ plane. In the embodiments, there is a relationship between ξ, and η and θm described below: 2×ξ=|2×θ 1 |, 2×η=|2×(θ 2 −2×θ 1 )| Furthermore, there is no eccentricity of planes within the XZ and XY planes. Additionally, the y-axis and z-axis of the local coordinates (x, y, z) of the (m)th surface are inclined by an angle θm within the YZ plane with respect to the global coordinate system (X, Y, Z) and are specifically set as follows: {circle around (4)} z-axis: A straight line which passes through the origin of the local coordinates and is inclined by an angle θm counterclockwise within the YZ plane with respect to the Z direction in the global coordinate system. {circle around (5)} y-axis: A straight line which passes through the origin of the local coordinates and forms 90° counterclockwise within the YZ plane with respect to the z direction. {circle around (6)} x-axis: A straight line which passes through the origin of the local coordinates and is perpendicular to the YZ plane. {circle around (7)} Lm is scalar indicating the distance between the origins of local coordinates of the (m)th and (m+1)th surfaces. L 6 is the distance from the 6th mirror to the surface of the image. Moreover, as described above, both the global coordinates and local coordinates use the YZ plane and yz plane as the meridional cross sections of their respective optical systems. The optical system of the embodiments have at least a rotationally asymmetrical aspheric surface and the shape is expressed in the local coordinate system by the following expression, where C 02 , C 20 , C 03 , C 21 , C 04 , C 22 , C 40 , C 05 , C 23 , C 41 , C 06 , C 24 , C 42 and C 60 are aspheric surface coefficients. z=C 02 y 2 +C 20 x 2 +C 03 y 3 +C 21 x 2 y+C 04 y 4 +C 22 x 2 y 2 +C 40 x 4 +C 05 y 5 +C 23 x 2 y 3 +C 41 x 4 y+C 06 y 6 +C 24 x 2 y 4 +C 42 x 4 y 2 +C 60 x 6   (5) Since the above-described curved surface expression (5) consists of only terms of even degrees with respect to x, the curved surface specified by the above-described curved surface expression is plane-symmetric with the yz plane as the symmetric plane. The above-described curved surface expression also expresses a shape symmetric with respect to the xz plane when the following condition is satisfied: C 03 =C 21 =C 05 =C 23 =C 41 =0 Furthermore, it expresses a rotationally symmetric shape when the following conditions are satisfied: C 02 =C 20 C 04 = C 40 = C 22 /2 C 06 = C 60 = C 24 /3 =C 42 /3 When the above-described conditions are not satisfied, it expresses a rotationally asymmetric shape (shape of free form surface). Then, embodiments of the present invention will be explained. FIG. 1 and FIG. 2 show the entire optical path from the reflection projection optical system (image-forming optical system) formed of free form reflection mirrors up to a screen 10 . FIG. 1 is a schematic view showing the configuration of a projection type image display apparatus using the projection optical system. FIG. 2 is an overall view of the projection optical system in FIG. 1 . With respect to numerical examples, only design values will be shown and drawings will be omitted, but they have almost the same configuration as this embodiment. This embodiment is a projection optical system that projects light whose intensity is modulated onto the screen 10 by the image display element 1 and uses an off-axial system to form an image on the screen. In FIG. 1 , the surface of the object coincides with the surface of the image display element 1 . The image display element 1 is illuminated by luminous flux emitted from an illumination system (not shown) and transmitting through the element 1 from the back. The illumination system is constructed of a lamp, condenser lens and filter for selecting a wavelength, etc. Furthermore, this embodiment has a configuration whereby three RGB image display elements are used to combine RGB three color image light components through a color combining prism 2 and project the combined light. However, FIG. 1 only shows one image display element 1 . This embodiment is constructed of six reflecting surfaces of a first mirror (concave surface) 3 , second mirror (convex surface) 4 , third mirror (concave surface) 5 , fourth mirror (convex surface) 6 , fifth mirror (concave surface) 7 and sixth mirror (concave surface) 8 . An aperture-stop S is placed between the second mirror 4 and third mirror 5 . The luminous flux from the image display element 1 is reflected by the first mirror to transform into substantially parallel luminous flux and then reflected by the second mirror 4 while being kept substantially parallel. All the above-described reflecting surfaces are only symmetric with respect to the YZ plane and rotationally asymmetric. The luminous flux emitted from the image display element 1 forms an intermediate image on an intermediate image forming surface between the fifth mirror 7 and sixth mirror 8 and the image of the aperture-stop S is formed at a position behind the sixth mirror 8 (on the screen 10 side). In the following numerical embodiments, the size of the image display element 1 is diagonal 0.7 inches (10.7×14.2 mm). Furthermore, the size of the screen 10 is diagonal 70 inches of an aspect ratio 3:4 (1067×1422 mm). The normal of the screen 10 is inclined 40 degrees with respect to the reference axis immediately before incidence upon the screen 10 . By the way, the projection optical system of the present invention may also be constructed to have lens systems and other reflection optical systems in addition to the optical system shown in FIG. 1 and FIG. 2 . The features of the projection optical system (image-forming optical system) of this embodiment will be explained below. Here, it is the prerequisite that the first mirror 3 is provided with power to transform the luminous flux spread from the image display element 1 to substantially parallel luminous flux and the second mirror 4 is provided with moderate power to reflect this substantially parallel luminous flux as is. First, the projection optical system according to this embodiment satisfies the following condition: |Arctan(1/2 F )−|2×(ξ−η)||≦10[deg]  (1) where ξ is an absolute value of an angle formed by the normal of the first mirror 3 (that is, the local z-axis in the first mirror 3 ) and the reference axis at an intersection of the reference axis and the surface of the first mirror 3 , η is an absolute value of an angle formed by the normal of the second mirror 4 (that is, the local z-axis in the second mirror 4 ) and the reference axis at an intersection of the reference axis and the surface of the second mirror 4 , and F is an effective F number on the first conjugate point (image display element 1 ) side. Expression (1) is a condition to enable luminous fluxes folded by reflections on the first mirror 3 and second mirror 4 to come as close as possible to each other. Within the meridional cross section, a marginal light ray on the optical path from the image display element 1 to the first mirror 3 and a marginal light ray on the optical path of the luminous flux reflected by the second mirror 4 are nearly parallel on the neighboring sides, and therefore when, for example, the first mirror 3 and third mirror 5 are placed side by side, it is possible to shorten the distance between the spatial positions of these first and third mirrors, and as a result, it is possible to make a configuration of these neighboring mirrors more compact. When F is the effective F number on the image display element 1 side of the optical system, the angle formed by the marginal light ray on the optical path from the image display element 1 to the first mirror 3 with respect to the reference axis on the same optical path is given as: Arctan(1/2F)  (1-a) The luminous flux from the first mirror 3 at the height of each object is converged into substantially parallel luminous flux and reaches the second mirror 4 . Then the luminous flux reflected by the second mirror 4 forms the following angle with respect to the reference axis: 2×(ξ−η)  (1-b) The luminous flux reflected by the second mirror 4 is substantially parallel luminous flux, and therefore the marginal light ray also has a similar angle. At this time, if the marginal light rays on the neighboring sides are nearly parallel to each other, that is, the difference in absolute values of the angles shown in expressions (1-a) and (1-b) is set to 10° or less including certain margins, it is possible to bring the optical path from the image display element 1 to the first mirror 3 sufficiently close to the optical path of the luminous flux reflected by the second mirror 4 without interfering with each other. Thus, from expressions (1-a) and (1-b), the above-described expression (1) is obtained as the conditional expression concerning the absolute value of the angle. Then, when P is the size of the display surface of the image display element 1 within the meridional cross section, F is an effective F number on the image display element 1 side of the optical system, L 0 ′ is an air equivalent distance along the reference axis from the image display element 1 to the first mirror 3 , and L 1 is an air equivalent distance along the reference axis from the first mirror 3 to the second mirror 4 , the following condition should be satisfied: 2.3≧2 ×L 1 ×sin η/Φ 1 ≧1.1  (2) where, Φ 1 =L 0 ′/ F+P   (3) Expression (2) indicates the condition for preventing each mirror from becoming too large and setting each mirror to a size within the necessary minimum range so that luminous fluxes do not interfere with each other. Φ 1 indicated by Expression (3) is an approximation of the effective diameter of luminous flux in the meridional section of the image display element 1 on the first mirror 3 . By the way, when a prism (e.g., color combining prism), etc. is placed on the optical path between the image display element 1 and the first mirror 3 , the above-described air equivalent distance L 0 ′ can be calculated as: L 0 ′= D 0 + D 1 / N+L 0   (2-a) where D 1 is a thickness of the prism measured along the reference axis, N is a refraction index of the glass of the prism, D 0 is a distance measured along the reference axis from the image display element 1 to the prism incident end and L 0 is a distance measured along the reference optical axis from the prism exiting end to the first mirror 3 . Furthermore, 2×L 1 ×sin η  (2-b) indicates an approximate distance of the light ray (reference light ray) on the reference axis, which progresses after being reflected at the center of the first mirror 3 and reflected by the second mirror 4 , from the center of the first mirror 3 when this light ray passes right next to the first mirror 3 . In the case where the above-described third mirror 5 is provided as described in this embodiment, the third mirror 5 is often necessarily placed next to the first mirror 3 on the substantially same plane in order to design a compact optical system. In this case, the value in above-described expression (2-b) is a value that can be said to be the distance between the center of the first mirror 3 and the center of the third mirror 5 . If the distance according to above-described expression (2-b) is too long, the first mirror 3 is distant from the third mirror 5 , which increases the size of the optical system. If the distance is too short, the luminous flux on the first mirror 3 overlaps with the luminous flux of the third mirror 5 , failing to establish the optical system. Since luminous flux is transformed to substantially parallel luminous flux by the first mirror 3 and the second mirror 4 has only weak power that preserves the condition, the diameter of luminous flux on the first mirror 3 is almost equivalent to the diameter of luminous flux on the third mirror 5 . Therefore, the following expression (2-c) expresses the magnitude of the value in expression (2-b) corresponding to the value in expression (3), that is, the distance from the center the first mirror 3 to the center of the third mirror 5 (reference axis of the reflection optical path from the second mirror 4 ) corresponding to the effective diameter of luminous flux on the first mirror 3 . If: 2×L 1 ×sin η/Φ 1   (2-c) is within the range of 1.1 times to a maximum of 2.3 times (that is, if above-described expression (2) is satisfied) including various margins, it is possible to provide an optical system of an appropriate size which is not too large or which prevents luminous fluxes from interfering with each other. Furthermore, in this embodiment, when the first to final (k)th mirrors are provided, in the order in which luminous flux progresses from the image display element 1 side, the (k−1)th, (k−2)th and (k−3)th mirrors are given positive, negative and positive power, respectively and the (k)th mirror is given positive power. Thus, arranging the three mirrors immediately before the final mirror as positive, negative and positive, that is, concave, convex and concave mirrors provides a power configuration similar to the Offner type, which is known to be non-aberration optical system with a reflection type equimultiple exposure apparatus, etc. This makes it unlikely to cause unnecessary adverse influences on luminous fluxes whose aberration has been corrected by mirrors immediately before the three mirrors. Further, making the surfaces of these three mirrors rotationally asymmetric (free form surfaces) allows the residual aberration components that have not been successfully removed from the surfaces before the above-described three mirrors to be effectively corrected. Then, as it is known that using a positive or concave mirror as the final mirror is advantageous in correcting aberration for projection at a high angle of elevation, it is possible to form an image of the aperture-stop after the final mirror (projection surface side). Furthermore, when the distances along the reference axis from the (k−1)th and (k−2)th curved mirrors to the next (k)th and (k−1)th curved mirrors are L(k−1) and L(k−2), respectively, the following condition should be satisfied. L ( k −1)> L ( k −2)  (4) In the case of projection at a high angle of elevation, forming an image of the aperture-stop after the final mirror is known to be advantageous in correcting aberration of the optical system. And this expression (4) is expressed also as an effective condition to prevent spatial interference between the luminous flux reflected by the final mirror and directed to the projection surface, and the edge of the preceding mirror. Furthermore, in the case where a concave mirror is used for the final mirror, spatially separating the light rays forming respective portions of an angle of view on this concave surface as much as possible, when the light rays are reflected on the concave surface, is advantageous in correcting aberration. This has an effect of making it easier to correct aberration remaining for each portions of the angle of view through control of local surface shapes on the final mirror and correct distortion of the diagonally projected image by controlling the curvature of the field. As the configuration condition for this, when the system is constructed of a total of k surfaces and the distances along the reference axis from the (k−1)th and (k−2)th curved mirrors to the next (k)th and (k−1)th curved mirrors are L(k−1) and L(k−2), the above-described expression (4) should be satisfied. Satisfying this condition makes it possible to place only the final mirror at a place more distant from the immediately preceding mirror with regard to distances among the mirrors. This produces an extra space for the space around the final mirror, avoiding interference in configuration such as eclipse of luminous flux or making it easier to adopt a configuration for reflecting luminous flux while keeping a tendency of separating luminous flux at each portion of the angle of view on the surface of the final mirror. By satisfying the above-described conditions, it is possible to realize an image-forming optical system suitable as the image-forming optical system for a projection type image display apparatus especially using a transmission type image display element, only made up of reflecting surfaces combining a plurality of curved mirrors, whose object side is substantially telecentric, bright (e.g., brighter than F3.0), avoiding size expansion of the mirrors and capable of projection at a high angle of elevation. Numerical embodiments of the present invention will be shown below. In all the numerical embodiments: {circle around (1)} The total number of reflection curved surfaces is 6. {circle around (2)} The distance D 0 from the surface of an object (image display element 1 ) to the color combining prism 2 is 11.0 mm. {circle around (3)} The thickness D 1 of the color combining prism 2 is 28.0 mm. {circle around (4)} The refraction index Nd of the color combining prism 2 is 1.872690 and Abbe's number νd is 32.33. {circle around (5)} The distance L 0 from the exiting end surface of the prism 2 to the local coordinate origin of the first mirror 3 is 40.0 mm. (Numerical Embodiment 1) Table 1 shows design values according to numerical embodiment 1. Configuration data is numbered sequentially from the surface of the image display element 1 to the surface of the image (surface of the screen 10 ). The F number on the object side is 2.0. TABLE 1 1st Mirror L 1 60 θ 1 −27 C2 −2.62990E−03 C3 −2.16320E−07 C4 −1.20530E−07 C5 −1.49020E−09 C6 −1.36120E−11 C20 −1.59860E−03 C21 −1.06840E−05 C22 −1.47820E−07 C23 −6.39140E−11 C24 2.09980E−11 C40 −1.12010E−07 C41 −1.06060E−09 C42 −2.51680E−11 C60 −2.01920E−11 2nd Mirror L 2 58 θ 2 −17 C2 2.57220E−04 C3 −1.26550E−05 C4 −1.68350E−07 C5 −1.37600E−09 C6 −2.05140E−11 C20 6.90530E−04 C21 −1.29610E−05 C22 −1.45430E−07 C23 −2.12890E−09 C24 −2.81640E−11 C40 −1.00680E−07 C41 −1.71720E−09 C42 −3.23350E−11 C60 −4.62060E−12 3rd Mirror L 3 60 θ 3 −6 C2 −2.88920E−03 C3 −1.27960E−05 C4 8.15880E−08 C5 −1.26220E−09 C6 8.58590E−13 C20 −3.93300E−03 C21 −4.86140E−06 C22 4.39810E−08 C23 −3.36290E−09 C24 1.91890E−11 C40 −3.49090E−08 C41 −1.04590E−09 C42 9.92250E−12 C60 −5.89450E−13 4th Mirror L 4 60 θ 4 +7 C2 −4.66820E−03 C3 −2.20370E−06 C4 4.58740E−07 C5 −4.70960E−09 C6 −8.87360E−11 C20 −7.09870E−04 C21 1.03720E−04 C22 −4.49650E−07 C23 −3.48160E−08 C24 1.81040E−10 C40 −4.09900E−08 C41 −1.14720E−08 C42 4.39340E−10 C60 −1.37690E−10 5th Mirror L 5 90 θ 5 +18 C2 −2.87050E−03 C3 −4.52490E−07 C4 −2.48480E−08 C5 −8.63240E−10 C6 1.23230E−11 C20 −1.14370E−02 C21 5.48810E−05 C22 −6.98790E−07 C23 4.50210E−09 C24 −7.34250E−11 C40 −9.51650E−07 C41 1.28360E−08 C42 −2.39830E−10 C60 2.20530E−11 6th Mirror L 6 2360 θ 6 +15 C2 3.11270E−03 C3 −2.39510E−05 C4 3.15000E−07 C5 −3.11740E−09 C6 1.50310E−11 C20 −1.10200E−03 C21 −1.48510E−05 C22 −3.39740E−07 C23 5.01470E−09 C24 −7.54510E−11 C40 −9.93860E−08 C41 9.25250E−10 C42 4.09830E−11 C60 2.63620E−11 (Numerical Embodiment 2) Table 2 shows design values according to numerical embodiment 2. The F number on the object side is 2.2. TABLE 2 1st Mirror L 1 60 θ 1 −27 C2 −3.45470E−03 C3 −3.43110E−06 C4 −1.18920E−07 C5 −1.10840E−09 C6 −1.75660E−11 C20 −3.86300E−03 C21 −2.80060E−05 C22 −4.51860E−07 C23 −2.65260E−09 C24 −1.78960E−11 C40 1.13220E−07 C41 −1.85280E−09 C42 −6.53940E−11 C60 5.04350E−11 2nd Mirror L 2 58 θ 2 −17 C2 −8.95970E−05 C3 −1.16880E−05 C4 −2.46060E−07 C5 −2.31260E−09 C6 −5.05480E−11 C20 −7.08200E−03 C21 −7.05900E−05 C22 −7.00660E−07 C23 −7.54210E−09 C24 −1.17420E−10 C40 2.30970E−07 C41 −1.04850E−09 C42 −7.24290E−11 C60 1.76270E−10 3rd Mirror L 3 60 θ 3 −6 C2 −2.97790E−03 C3 −1.31910E−05 C4 4.97300E−08 C5 −9.14870E−10 C6 −4.76540E−12 C20 −5.95630E−03 C21 1.40430E−07 C22 −1.76920E−07 C23 −1.80170E−09 C24 2.84940E−12 C40 −1.97720E−07 C41 9.89490E−11 C42 −1.36170E−11 C60 −1.31600E−11 4th Mirror L 4 60 θ 4 7 C2 −3.22570E−03 C3 −5.14890E−06 C4 3.03330E−07 C5 −2.94870E−09 C6 4.21640E−11 C20 −2.32130E−03 C21 1.62720E−04 C22 −1.37010E−06 C23 9.54750E−09 C24 −1.38730E−10 C40 −3.60700E−07 C41 −3.32270E−08 C42 5.26710E−10 C60 3.74070E−10 5th Mirror L 5 90 θ 5 18 C2 −3.23350E−03 C3 4.40360E−06 C4 1.50230E−08 C5 5.95530E−10 C6 5.44740E−12 C20 −1.13810E−02 C21 −1.24900E−05 C22 3.15290E−07 C23 3.29840E−10 C24 7.28890E−12 C40 −9.66530E−07 C41 −5.75770E−09 C42 2.69510E−10 C60 −2.18500E−10 6th Mirror L 6 2360 θ 6 15 C2 1.34650E−03 C3 −1.68040E−06 C4 9.91660E−08 C5 −1.55470E−09 C6 1.11750E−11 C20 −1.14430E−04 C21 −7.55550E−06 C22 1.11850E−07 C23 7.43030E−10 C24 −3.55670E−11 C40 1.54350E−07 C41 5.83010E−09 C42 2.29590E−11 C60 −5.96550E−12 (Numerical Embodiment 3) Table 3 shows design values according to numerical embodiment 3. The F number on the object side is 2.5. TABLE 3 1st Mirror L 1 60 θ 1 −27 C2 −2.82290E−03 C3 −8.39020E−06 C4 −2.15920E−07 C5 −1.73820E−09 C6 −1.18040E−11 C20 −2.92540E−03 C21 −2.56290E−05 C22 1.77300E−08 C23 2.67590E−09 C24 1.17010E−11 C40 5.95940E−08 C41 −2.55510E−09 C42 −4.38720E−11 C60 1.72090E−11 2nd Mirror L 2 58 θ 2 −17 C2 6.15930E−05 C3 −2.04790E−05 C4 −2.61300E−07 C5 −3.05570E−09 C6 −4.74500E−11 C20 −2.76560E−03 C21 −1.07810E−05 C22 4.56360E−07 C23 7.40050E−09 C24 9.86610E−11 C40 5.81510E−08 C41 7.63600E−10 C42 2.34840E−11 C60 2.62710E−11 3rd Mirror L 3 60 θ 3 −6 C2 −2.47730E−03 C3 −1.69230E−05 C4 1.07440E−07 C5 −1.48060E−09 C6 −3.79440E−12 C20 −5.26230E−03 C21 7.37020E−06 C22 1.07850E−07 C23 −2.48380E−09 C24 4.52080E−11 C40 −1.42710E−07 C41 4.94900E−10 C42 4.14600E−11 C60 −7.30370E−12 4th Mirror L 4 60 θ 4 7 C2 −2.03880E−03 C3 −2.71950E−08 C4 1.18910E−07 C5 −1.99550E−09 C6 −3.81030E−11 C20 −1.44660E−03 C21 1.87520E−04 C22 −8.91840E−07 C23 −3.74300E−09 C24 9.17790E−11 C40 −2.20620E−06 C41 −4.66870E−08 C42 9.73520E−10 C60 1.76210E−09 5th Mirror L 5 90 θ 5 18 C2 −1.68920E−03 C3 2.01510E−06 C4 −1.62160E−07 C5 −1.10580E−09 C6 1.88300E−11 C20 −1.06760E−02 C21 2.38450E−05 C22 −8.61220E−08 C23 −4.13700E−09 C24 −5.56080E−11 C40 −7.14770E−07 C41 3.19510E−09 C42 −8.22270E−11 C60 −8.16020E−11 6th Mirror L 6 2360 θ 6 15 C2 3.65330E−03 C3 −2.17560E−05 C4 2.66200E−07 C5 −2.74490E−09 C6 1.44350E−11 C20 −2.71280E−03 C21 −3.02460E−06 C22 −4.83180E−07 C23 5.47270E−09 C24 −7.46490E−11 C40 6.47570E−07 C41 4.93880E−09 C42 2.53670E−10 C60 −1.76960E−10 (Numerical Embodiment 4) Table 4 shows design values according to numerical embodiment 4. The F number on the object side is 2.8. TABLE 4 1st Mirror L 1 60 θ 1 −27 C2 -2.8898E−03 C3 -7.8773E−06 C4 -2.0967E−07 C5 -1.7026E−09 C6 -1.3058E−11 C20 -2.8814E−03 C21 -2.4490E−05 C22 5.8433E−08 C23 3.4577E−09 C24 1.6376E−11 C40 9.1834E−08 C41 -2.6967E−09 C42 -3.4943E−11 C60 3.2961E−11 2nd Mirror L 2 58 θ 2 −17 C2 5.0246E−05 C3 -1.9943E−05 C4 -2.5939E−07 C5 -2.8618E−09 C6 -4.8075E−11 C20 -2.8115E−03 C21 -5.9288E−06 C22 5.7097E−07 C23 8.8495E−09 C24 1.1055E−10 C40 7.4373E−08 C41 1.1162E−09 C42 2.6441E−11 C60 3.1819E−11 3rd Mirror L 3 60 θ 3 −6 C2 -2.4331E−03 C3 -1.7384E−05 C4 1.1195E−07 C5 -1.4727E−09 C6 -5.4818E−12 C20 -5.3683E−03 C21 8.8846E−06 C22 1.3012E−07 C23 -2.2319E−09 C24 4.8964E−11 C40 -1.5317E−07 C41 7.2041E−10 C42 4.6359E−11 C60 -8.3890E−12 4th Mirror L 4 60 θ 4 7 C2 -1.9285E−03 C3 -9.3206E−07 C4 1.3423E−07 C5 -2.0951E−09 C6 -4.4435E−11 C20 -2.3054E−03 C21 2.1589E−04 C22 -1.0703E−06 C23 -2.8856E−09 C24 8.3340E−11 C40 -2.5050E−06 C41 -5.6641E−08 C42 1.2383E−09 C60 2.2638E−09 5th Mirror L 5 90 θ 5 18 C2 -1.5474E−03 C3 2.5468E−06 C4 -1.8768E−07 C5 -1.5289E−09 C6 2.3362E−11 C20 -1.0472E−02 C21 1.9738E−05 C22 1.6806E−08 C23 -4.6789E−09 C24 -6.4027E−11 C40 -7.1077E−07 C41 2.4256E−09 C42 -4.9469E−11 C60 -1.1212E−10 6th Mirror L 6 2360 θ 6 15 C2 3.5875E−03 C3 -2.0414E−05 C4 2.4500E−07 C5 -2.4251E−09 C6 1.1429E−11 C20 -2.7382E−03 C21 -1.9202E−06 C22 -4.9902E−07 C23 5.3182E−09 C24 -7.0459E−11 C40 6.8669E−07 C41 4.8212E−09 C42 2.8058E−10 C60 -2.0137E−10 Here, the calculation results of the above-described expressions (1) and (4) in the above-described numerical embodiments are shown. TABLE 5 Expression (1) a b ≦10° F ξ η Arctan (1/2F) | 2(ξ − η) | |a − b| Judgement Embodiment 1 2.0 27 37 14.036 20 5.9638 available Embodiment 2 2.2 27 37 12.804 20 7.1957 available Embodiment 3 2.5 27 37 11.310 20 8.6901 available Embodiment 4 2.8 27 37 10.125 20 9.8753 available TABLE 6 Expression (4) 2.3 ≦ Expression ≦ 1.1 DO D1 N LO F P φ1 L1 η 2L1sinη 2L1sinη/φ1 Judgement Embodiment 1 11 28 1.87269 40 2.0 5.4 38.376 60 37 72.2178 1.882 available Embodiment 2 11 28 1.87269 40 2.2 6.4 36.378 60 37 72.2178 1.985 available Embodiment 3 11 28 1.87269 40 2.5 7.4 33.781 60 37 72.2178 2.138 available Embodiment 4 11 28 1.87269 40 2.8 8.4 31.954 60 37 72.2178 2.260 available The above embodiments have described the projection type image display apparatuses, but the present invention is also applicable to an image pickup optical system. When an image-forming optical system of the present invention is used as an image pickup optical system, as shown in FIG. 3 , the positions of the object and image of the above-described optical system can be switched round. Then, the image display element may be replaced by an image pickup element 20 such as a CCD or CMOS sensor, and the image of the object 40 is formed on the image pickup element 20 through 30 by the image-forming optical system according to the invention. In the case where a color CCD is used as the image pick element 20 , color images can be taken by a single CCD, and therefore no prism is required. Further, changing the specification as appropriate according to the operating conditions such as shortening the focal length compared to the projection type image display apparatus makes it possible to realize an apparatus to read a document placed on a flat surface from diagonal direction as in the case of an art camera. In addition, the present invention can also be used as a general image pickup apparatus such as a monitoring camera. When the image-forming optical system is used for an image pickup system, the image pickup system has the merit of producing no color aberration as far as the system is a surface reflection system as in the case of a projection system. For example, the prism for combining RGB three-color liquid crystal images for the projection type image display apparatus can be changed to a cover glass (a thin plate of approximately 0.7 mm in thickness) of the CCD. To be precise, since the above-described prism and cover glass are refraction elements, color aberration may be generated there, but the operating conditions are limited in a projection system, and therefore it is possible to remove influences of color aberration through an adjustment and make the most of the feature of being free of color aberration of the reflection image-forming optical system. On the other hand, in the case of the image pickup system, conditions such as image pickup distance may vary, etc., but the cover glass is thin, and therefore little color aberration is generated here and there are possibly no substantial influences. As described above, according to the present invention, it is possible to bring luminous fluxes folded by reflections on the first mirror and second mirror of the image-forming optical system close to each other without interference with each other and thereby reduce the size of the image-forming optical system made up of only reflecting surfaces. Furthermore, the present invention can prevent the mirrors from becoming too big and reduce them to within a minimum necessary range preventing luminous fluxes from interfering with each other and thereby reduce the size of the image-forming optical system. Moreover, the three positive, negative and positive mirrors before the final mirror can optimally correct various aberrations and use of a positive mirror for the final mirror can form an image of the aperture-stop after the final mirror (projection surface side), which is advantageous in correcting aberration for projection at a high angle of elevation. Furthermore, when an image of the aperture-stop is formed after the final mirror, the image-forming optical system can prevent spatial interference between the luminous flux directed to the projection surface and the edge of the mirror immediately before the final mirror. For the above-described reasons is it possible to realize an image-forming optical system which is especially suitable for the projection type image display apparatus using a transmission type image display element. Further, it is possible to realize an image-forming optical system which is made up of only reflecting surfaces by a combination of a plurality of curved mirrors and whose object side is substantially telecentric, bright, preventing expansion in the size of mirrors, capable of projection at a high angle of elevation. While preferred embodiments have been described, it is to be understood that modification and variation of the present invention may be made without departing from the sprit or scope of the following claims.

The present invention discloses an image-forming optical system provided with a plurality of curved mirrors whereby two points at different distances are made to have an optically conjugate relationship, sequentially starting with a first conjugate point which is nearer when an optical path is traced from the first conjugate point to a second conjugate point which is farther, comprises, a first mirror which reflects luminous flux from the first conjugate point to transform the luminous flux into substantially parallel luminous flux, and a second mirror which reflects the luminous flux reflected by the first mirror while keeping the luminous flux substantially parallel. Further, the optical system satisfies the following condition: |Arctan(1/2 F )−|2×(ξ−η)||≦10[deg]

This application is a continuation of application Ser. No. 07/591,891, filed on Oct. 2, 1990, now abandoned. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to fiber-reinforced molding compositions having superior mechanical properties which are based on polyphenylene ether resins, and also to a process for the preparation of these molding compositions. 2. Description of The Background Polyphenylene ethers (PPE), also known as polyphenylene oxides, are polymers having a high heat resistance and also good mechanical and electrical properties. As a rule, they are used as blends with polystyrene resins, for example, DE-C-2,119,301 and 2,211,005 and/or polyoctenylene (DE-A-3,442,273 and 3,518,277). Many attempts have been made to increase the rigidity of PPE-containing molding compositions by admixing reinforcing fibers composed of inorganic or organic material in the resin. For instance, DE-A-2,364,901 discloses polymer mixtures of PPE, polystyrene resins and glass fibers, the glass fibers used in this case having a length of between 3.1 and 25.4 mm, preferably of below 6.35 mm. EP-A-0,243,991 and the corresponding U.S. Pat. No. 4,749,737 describe the mixing of very short, unsized fibers with Si-H bond-containing siloxanes, to improve the fiber-matrix adhesion in the composition, followed by mixing in the melt with PPE and a polystyrene resin. A specific modification of the fiber surface by treating the glass fibers with vinylsilanes or gamma-glycidoxypropyl-trimethoxysilanes for use in PPE-containing molding compositions is described in DE-A-2,132,595, JP 73/97,954, JP 74/10,826 and JP 85/88,072. DE-A-2,719,305 proposes the opposite method, i.e. end-group modification of the PPE via a silylation carried out before compounding. This technique however is a roundabout and labor-intensive method of achieving an improved fiber-matrix coupling. A commonly used surface modification of the reinforcing fibers is achieved by treatment with aminoalkylsilanes, for example gamma-aminopropyltriethoxysilane. Glass fibers which have been sized in this manner are incorporated in numerous PPE-containing compositions, it always being necessary to additionally modify the composition of the thermoplastic matrix to bond the fibers to the matrix. For instance, JP 87/15,247 describes the addition of, for example, maleic anhydride-modified polypropylene. JP 85/46,951 describes the addition of ethylene-maleic anhydride copolymers and JP 85/44,535, DE-A-3,246,433 and JP 82/168,938 describe the addition of styrene-maleic anhydride copolymers. However, these polymeric additives have the disadvantage that they reduce the heat resistance of the molding compositions or else they are only partly compatible with the PPE matrix or in most cases are incompatible and therefore impair the mechanical properties of the molding compositions. A need continues to exist for a PPE based molding composition of improved mechanical properties. SUMMARY OF THE INVENTION Accordingly, one object of the present invention is to provide fiber-reinforced molding compositions based on PPE, which, while avoiding the disadvantages described above, exhibit an improved adhesion between fiber and matrix. Briefly, this object and other objects of the present invention as hereinafter will become more readily apparent can be attained by a molding composition comprising a) 97 to 50% by weight, relative to the sum of (a) and (b), of a mixture of 30 to 100 parts by weight of a polyphenylene ether, 0 to 70 parts by weight of a styrene polymer, 0 to 10 parts by weight of a polyoctenylene and 0.1 to 2.5 parts by weight of an α-β-unsaturated carboxylic acid derivative or a precursor thereof; b) 3 to 50% by weight of carbon fibers and/or glass fibers whose surfaces bear functional groups which are capable of entering into chemical coupling reactions with α,β-unsaturated carboxylic acid derivatives; and optionally c) dyes, pigments, plasticizers, flame retardant additives, processing auxiliaries, other customary additives or combinations thereof. DESCRIPTION OF THE DRAWINGS A more complete understanding of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: FIG. 1 is a scanning electron micrograph of the fiber reinforced molding composition of Comparative Example A; and FIGS. 2a and 2b are scanning electron micrographs of the fiber reinforced molding composition of Example 2 of the present invention, wherein FIG. 2b is an enlargement of FIG. 2a. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The molding compositions of the invention can be processed to give molded articles by the customary methods of thermoplastics processing, for example injection molding or press molding. Suitable polyphenylene ethers include primarily polyethers based on 2,6-dimethylphenol, the ether oxygen of one unit being bonded to the benzene nucleus of the adjacent unit. In principle, it is also possible to use other o,o'-dialkylphenols whose alkyl radical preferably contains a maximum of 6 carbon atoms as long as this radical does not have a tertiary carbon atom in the alpha position. Furthermore, it is possible to use phenols which are substituted only in one ortho-position by a tertiary alkyl radical, in particular a tertiary butyl radical. Each of the monomeric phenols listed may be substituted by a methyl group in the 3-position, and optionally also in the 5-position. Obviously, it is also possible to use mixtures of the monomeric phenols mentioned here. The polyphenylene ethers may be prepared, for example, in the presence of complex-forming agents such as copper bromide and morpholine, from the phenols as disclosed in DE-A-3,224,692 and 3,224,691. The viscosity numbers J, determined in accordance with DIN 53 728 in chloroform at 25° C. are in the range of from 35 to 80 cm 3 /g (concentration 5 g/l). Preference is given to the polymer of 2,6-dimethylphenol, poly-(2,6-dimethyl-1,4-phenylene ether), having a viscosity number J from 45 to 70 cm 3 /g. Normally, the polyphenylene ethers are used in the form of powders or granules. The polyoctenylenes are prepared by the ring-opening or ring-expanding polymerization of cyclooctene (see, for example, A. Draxler, Kautschuk+Gummi, Kunststoffe 1981, pages 185 to 190). Polyoctenylenes having different proportions of cis- and trans-double bonds and also different J-values and correspondingly different molecular weights are obtainable by methods known in the literature. Preference is given to polyoctenylenes having a viscosity number of from 50 to 350 cm 3 /g, preferably 80 to 160 cm 3 /g, determined on a 0.1% strength solution in toluene. 55 to 95%, preferably 75 to 85%, of their double bonds are in the trans-configuration. There are various methods of preparing a mixture of polyphenylene ether and the polyoctenylene. One method is to dissolve the two polymers in a suitable solvent and to isolate the mixture by evaporating off the solvent or by precipitating it with a non-solvent. Another method is to combine the two polymers in the melt. Further details are given in DE-A-3,518,277. In a preferred embodiment, the molding composition contains 1 to 10 parts by weight of polyoctenylene. α,β-Unsaturated carboxylic acid derivatives are understood to mean, for example, compounds of the formulae (I) and (II): R.sup.1 --CO--CR.sup.2 ═CR.sup.3 --CO--R.sup.4 (I) R.sup.1 --CO--CR.sup.2 ═CR.sup.3.sub.2 (II) in which R 1 and R 4 are hydroxyl, aryloxy and/or alkoxy groups having up to 12 carbon atoms or together are --O-- or --NR 5 --, R 2 and R 3 denote hydrogen, an alkyl or cycloalkyl group having up to 12 carbon atoms, an alkyl group substituted by the radical COR 1 , an aryl group, chlorine or together an alkylene group having up to 12 carbon atoms, while R 5 is hydrogen, alkyl, aralkyl or aryl groups, each having up to 12 carbon atoms. Examples of these acids are maleic acid, fumaric acid, itaconic acid, aconitic acid, tetrahydrophthalic acid, methylmaleic acid, maleic anhydride, N-phenylmaleimide, diethyl fumarate and butyl acrylate. In this selection, preference is given to the use of fumaric acid and maleic anhydride. Obviously, it is also possible to use mixtures. It is also possible to use precursors of α,β-unsaturated carboxylic acid derivatives of this type which, under the conditions of mixing in the melt, are converted to the said carboxylic acid derivatives by known reactions such as, for example, elimination or reverse Diels-Alder reaction. Obviously, it is possible to add other compounds which promote the incorporation of the α,β-unsaturated carboxylic acid derivatives, for example, by alternating copolymerization while grafting. Suitable compounds in this category are primarily vinylaromatics such as, for example, styrene, which enter into a reaction of this type in particular with maleic anhydride. The preparation of graft copolymers of this type is described in the German patent application DE-A-3,831,348. The styrene polymer which is optionally added during the preparation or the working-up of the polyphenylene ether should preferably be compatible with the polyphenylene ether used. Its molecular weight Mw is in the range from 1,500 to 2,000,000, preferably in the range from 70,000 to 1,000,000. Particularly preferred styrene polymers are polystyrene, impact-modified polystyrene and also styrene-butadiene copolymers. Obviously, mixtures of these polymers may also be used. The styrene-butadiene copolymers may be random, tapered or block copolymers. The toughness is increased by giving preference to the use of block copolymers of the A-B-A type. The polystyrene blocks A have an average molecular weight Mw of 4,000 to 150,000 and together make up to 33% by weight of the block copolymer. The polybutadiene block B, which may also be hydrogenated or partly hydrogenated, has an average molecular weight Mw of 20,000 to 480,000. The reinforcing fiber present in the molding composition of the invention bears on its surface preferably free amino, epoxide or isocyanate groups. Amino groups are introduced, for example, by sizing with a copolyamide, with low molecular weight amine compounds or specifically in the use of glass fibers, with gamma-aminopropyltriethoxysilane; epoxide groups by impregnation with uncrosslinked epoxy resins or, in the case of glass fibers, with gamma-glycidoxypropyltrimethoxysilane; isocyanate groups by sizing with a solution of uncrosslinked, preferably low molecular weight polyurethane resins. The components III are preferably used to a maximum amount of 30% by weight, relative to I. The individual components may be mixed either simultaneously or in succession. Generally, the unreinforced molding composition is initially prepared in granule or melt form and to this is admixed the functionalized fibers in a mixer having a good kneading action. This mixing may for example be carried out using a single or twin-screw kneader or co-kneader. Generally, the mixing temperature is between 250° and 350° C., preferably between 260° and 310° C., and the residence time is generally between 1 and 10 minutes, preferably between 3 and 5 minutes. The molding compositions of the invention can be processed by customary injection molding procedures under the same conditions as the corresponding prior-art thermoplastic molding compositions. Even large molded objects can be produced simply using the said molding compositions. The molding compositions of the invention are used to produce moldings which are subject to particular service stress (intermittent and/or constant), a good fiber-matrix adhesion being of crucial importance in these moldings. The molded objects are employed, for example, in the construction of machines and apparatus for example for gear wheels or pump components, in sporting equipment, in the motor vehicle industry or in the electrical industry. Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified. Comparative Example A 100 parts by weight of polyphenylene ether having a J-value of 68 cm 3 /g, which has been obtained by oxidative coupling of 2,6-dimethylphenol, termination of the reaction and subsequent combined reaction/extraction in accordance with DE-A-3,313,864 and 3,323,777 followed by evaporation of the solvent and extruding the melt via a degassing extruder, are remelted with 2 parts by weight of diphenylcresyl phosphate (DISFLAMOLL® DPK, Bayer) and one part of the antioxidant IRGANOX® 1010 and also 15.6 parts by weight of an NH 2 group-bearing carbon fiber (GRAFIL® XAS/PA 6, Courtaulds Advanced Materials), which are metered into the PPE melt in a twin-screw kneader at 280° C. Before the product is discharged, the volatile components are removed in a degassing zone. The product is granulated, dried and injection molded to give test pieces. The properties obtained from these are listed in Table 1. It can be seen clearly from the scanning electron micrograph (SEM) that no adhesion exists between fiber and matrix (low temperature fracture surface) (FIG. 1). EXAMPLES 1 to 3 The experiment described in Comparative Example A is repeated but with the addition of 0.5 to 1.5 parts by weight of maleic anhydride to the mixture of PPE, diphenylcresyl phosphate and IRGANOX® 1010 and subsequent metering of the carbon fiber into the melt. The constituents and properties of the composition prepared in this way are listed in Table 1. The scanning electron micrograph from Example 2 shows that an excellent adhesion exists between fiber and matrix (low temperature fracture surface) (FIGS. 2a and 2b). COMPARATIVE EXAMPLE B The experiment described in Comparative Example A is repeated but, instead of the carbon fiber used in that example, an epoxy resin-sized carbon fiber (TENAX® HTA-6-CN, Akzo (Enka AG) is used (Table 1). EXAMPLE 4 The experiment described in Comparative Example B is repeated but, as described in Examples 1 to 3, 1.5 parts of maleic anhydride are additionally used (Table 1). Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein. TABLE 1______________________________________ Example A 1 2 3 B 4______________________________________PPE Parts by 100 100 100 100 100 100 weightDiphenylcresyl Parts by 2 2 2 2 2 2phosphate weightIRGANOX ® Parts by 1 1 1 1 1 11010 weightMaleic Parts by -- 0.5 1 1.5 -- 1.5anhydride weightGRAFIL ® Parts by 15.6 15.6 15.6 15.6 -- --XAS/PA 6 weightTENAX ® Parts by -- -- -- -- 15.6 15.6HTA-6-CN weightModulus of MPa 8600 8400 9100 9200 7000 9500elasticity intensionDIN 53 457Tensile strength MPa 98 117 132 122 92 136DIN 53 455Elongation at % 1.5 1.8 1.9 2.2 1.9 1.8breakDIN 53 455Impact strength kJ/m.sup.2 13 17 17 13 14 16DIN 53 453______________________________________

A fiber-reinforced molding composition, comprising: a) 97 to 50% by weight, relative to the sum of (a) and (b), of a mixture of 30 to 100 parts by weight of a polyphenylene ether, 0 to 70 parts by weight of a styrene polymer, 0 to 10 parts by weight of a polyoctenylene and 0.1 to 2.5 parts by weight of an α,β-unsaturated carboxylic acid derivative or a precursor thereof; b) 3 to 50% by weight of carbon fibers and/or glass fibers whose surfaces bear functional groups which are capable of entering into chemical coupling reactions with the α,β-unsaturated carboxylic acid derivatives; and optionally c) dyes, pigments, plasticizers, flame retardant additives, processing auxiliaries, other customary additives or combinations thereof.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to electronic commerce. More specifically, it relates to a system for performing virtual customized vehicle design including component allocation and pricing; as well as financing, purchase, negotiation, and final acquisition using an internet capable computing device. [0003] 2. Description of the Prior Art [0004] With the development of electronic commerce in recent years, there has been a substantial increase in the availability and sophistication of commercial websites specializing in the sale and distribution of various products and services. These websites typically have software interfaces which allow consumers, or potential consumers, to browse products and services prior to selecting and finalizing a sale for a particular product, service, or combination of products. For certain products, specifically those which are customizable by the addition or subtraction of various components or subcomponents, it is desirable to provide an interface which allows the user to select the various components to be assembled, and/or added or subtracted to an underlying base product. The more sophisticated of such interfaces also allow the user to visualize a completed version of the product, while also providing information on the pricing of the product. [0005] Still other interfaces associated with commercial sites allow for performing various actions relating to the completion of a transaction for the sale of customized goods and services including various methods for payment. However, these interfaces have limited capability for allowing a user to perform all of the necessary steps for customizing a product such as a vehicle, as there are many issues which arise from the acquisition and integration of disparate components from a plurality of manufacturers and/or dealers, primarily issues involving the price, availability, and even compatibility of components selected for inclusion with the final product, as well as the price and availability of the completed product. A single interface which allows a user to resolve all of these issues is the primary object of the invention. [0006] The following known prior art has been directed to providing a summary of the various systems of the prior art. [0007] U.S. Pat. No. 7,353,192 issued to Ellis et al., discloses a system which allows for customizing a vehicle and viewing a virtual image of the vehicle prior to purchase. [0008] U.S. Pat. No. 7,542,925 issued to Tung discloses a system for customizing a plurality of domestic environments, complete with visualization of completed environments, which allows a user to select and have shipped a desired combination of furniture and interior decor items. [0009] None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. SUMMARY OF THE INVENTION [0010] Briefly, the invention comprises an electronic system for the customization, visualization, integration, purchase, and acquisition of a vehicle; the system implemented on a computer server or equivalent device, where the server is accessible over the interne via a suitable end-user operated computing device, the server generating a menu driven visual interface viewable on the computing device. The system allows for all aspects of a customized vehicle purchase to be performed by the user, substantially streamlining the selection and acquisition process. Once a vehicle is selected using the system interface, a three dimensional simulation is presented on the user device, along with an additional menu for selecting various components to be added to the vehicle. Selected components are displayed positioned at the appropriate position on or within the vehicle, the system automatically configuring the view most suitable for providing a realistic virtual image of the component in situ. In addition, the system will show the manufacturer's suggested retail price (MSRP) for the vehicle as currently configured, with the price updated in real time as components are added/deleted. The system can be configured for direct access by the user or for access through a dealer website, where, in the latter case, an adjusted price based on a particular dealer's pricing schedule will be displayed. Once all components are selected, the system will interface with the vehicle manufacturer's inventory database to search the inventory to ensure chosen component parts/options are in stock and if not, expected date of receipt, and reserve the chosen component parts/options and schedule the vehicle in the manufacturer's production schedule. If the system is accessed through a dealer website, the interface will then offer an opportunity to negotiate a final sales price with the dealer, offer financing and payment options either through the manufacture's or dealer's financing options, and at the end of the process provide an electronic and/or print out of a sales agreement. [0011] Accordingly, it is a principal object of the invention to provide a comprehensive system for performing virtual customized vehicle design including component allocation and pricing; as well as financing, purchase, negotiation, and final acquisition using an interne capable computing device. [0012] It is a major object of this invention to provide a comprehensive system for performing virtual customized vehicle design which can be used to design any motor vehicle including, but not limited to, automobiles, motorcycles, and RVs. [0013] It is another object to provide a comprehensive system for performing virtual customized vehicle design which can be implemented through a dealer website. [0014] It is another object to provide a comprehensive system for performing virtual customized vehicle design which allows for the inclusion of both components available from the manufacturer of a particular vehicle and compatible components from other manufacturers. [0015] It is another object to provide a comprehensive system for performing virtual customized vehicle design which allows the user to access price and availability of selected components. [0016] It is another object to provide a comprehensive system for performing virtual customized vehicle design which allows for display of a realistic three dimensional virtual image of a selected vehicle including real time depiction of the vehicle as various components are added/deleted. [0017] It is another object to provide a comprehensive system for performing virtual customized vehicle design which allows for negotiating a final sales price for a customized vehicle. [0018] It is another object of the invention to provide a comprehensive system for performing virtual customized vehicle design where a manufacturer builds custom vehicles exclusively in accordance with the method of the invention to substantially reduce parts inventory. [0019] Finally, it is a general goal of the invention to provide improved elements and components thereof in a system for the purposes described which is fully effective in accomplishing its intended purposes. [0020] Thus it can be seen that the potential fields of use for this invention are myriad and the particular preferred embodiment described herein is in no way meant to limit the use of the invention to the particular field chosen for exposition of the details of the invention. [0021] A comprehensive listing of all the possible fields to which this invention may be applied is limited only by the imagination and is therefore not provided herein. Some of the more obvious applications are mentioned herein in the interest of providing a full and complete disclosure of the unique properties of this previously unknown general purpose article of manufacture. It is to be understood from the outset that the scope of this invention is not limited to these fields or to the specific examples of potential uses presented hereinafter. [0022] These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. [0023] The present invention meets or exceeds all the above objects and goals. Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS [0024] Various other objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: [0025] FIG. 1 is a perspective view of an image of a vehicle shown on a product display screen to be customized in accordance with the inventive system. [0026] FIG. 2 is a graphical representation of the overall system of the invention illustrating the interconnection of the various computing resources necessary to perform the several functions of the invention. [0027] FIG. 3 is a flowchart of the system of the invention. [0028] FIG. 4 is a representation of a webpage associated with the system of the invention. [0029] FIG. 5 is a representation of a webpage associated with the system of the invention. [0030] FIG. 6 is a representation of a webpage associated with the system of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0031] Referring now to FIGS. 1 and 2 , a representative vehicle displayed on a simulated webpage, generally designated by the numeral 10 , is shown, the vehicle 10 to be customized and, if desired, purchased using the system of the present invention. The vehicle 10 can be modified both cosmetically and mechanically to enhance either aesthetics or performance or both. A key aspect of the invention is that a vehicle may be customized by the addition or removal of external and internal components using the system of the invention, with the resulting change in appearance, if any, being viewable on a product display screen transmitted to a user operated computing device or terminal 12 . In accordance with the method of the invention, the customized vehicle 10 would be available directly from a vehicle manufacturer (Ford, GM), where the manufacturer includes the selected components prior to shipping to a dealer selected by the user as described below. It can be appreciated that the vehicle manufacturer is in the best position to determine the compatibility of customizing components, and is therefore best able to choose the components from a wide variety of available components which can be most effectively integrated with a given vehicle. [0032] With particular reference to FIG. 2 , the system 14 may be provided as software for use with a host data processing or computing facility 18 . Single user operated computing devices such as a PC 12 may be selectively connected by one or more electronic networks 19 to various remote computing resources 16 , including the host computing facility 18 of the present invention, either by wire or wirelessly via, e.g., the internet or world wide web 19 . The computing devices 12 are operated by users authorized by the e.g., automobile manufacturer or dealer, to access system 14 , the level of access granted being variable. Typically, a user will not have full access to the system 14 until registering with the system and providing at least some identification, the details of the registration process being outside of the scope of this application. However, prior to accessing the system, the user will have to enter at least some data, including at least first and last name, e-mail address, phone number, street address including zip code, with the system 14 including a log in screen (not shown) displayable on the user terminal 12 to allow for the entry of the data. This minimal entry of data will limit casual price shopping to preserve system 14 computing resources, and can also be used by the system to determine delivery times and dealer locations as will be described in more detail later. [0033] The host computing facility 18 , which is of course typically operated by an entity engaged in the business of providing computing services and associated software to commercial entities (manufacturers of vehicles in the present example) engaged in interstate commerce as noted above, may include one or more servers 21 for volume data and program storage, including the software application necessary to implement the system 14 , and allows for inputting, accessing, (i.e. data capture), and editing all data necessary to allow the user of, e.g., a PC 12 to select, customize, and finally purchase an automobile. At least one intelligent client associated with the servers 21 allows for limited and secure access to the servers 21 . The host computing facility 18 allows for selectively accessing the remote computing resources 16 (e.g., manufacturer's servers for aftermarket manufacturers of the various components) for performing the various tasks associated with the system 14 , the resources 16 providing data relating to price, availability, compatibility, as well as other information necessary for the implementation of the system 14 as will be explained in more detail later. System administrators associated with computing facility 18 serve as a human interface to the system 10 and perform various tasks such as upgrading software, hardware maintenance, and communicating various reports and messages to users, including those associated with the manufacturer and or dealer of automobiles, or aftermarket manufacturers, as is known in the art. [0034] Referring again to FIG. 1 , the vehicle 10 is represented as a three dimensional image which may be from an actual photograph. In any event, the image of the vehicle 10 would be made as realistic as possible using CAD/CAM techniques as is known in the art. The vehicle 10 to be customized includes many interior and exterior components. By way of an example, two such components, the grill 30 and rims 32 are to be selected for customization by the user of PC 12 . The display screen or webpage 33 displaying the selected vehicle includes various icons/textboxes to allow the user to navigate the selection and customization process. A column of textboxes 34 , 36 includes identifying indicia appropriate to the component to be considered by the user. In the present example two textboxes 34 , 36 are shown, but in practice many will be displayed corresponding to a complete list of components which can be added to the particular vehicle selected. The list of components available for any particular vehicle will of course vary, as will the textboxes 34 , 36 and the underlying links. The user can request to view a selected component by clicking (with a computer mouse or equivalent webpage navigating device available for the end user device 12 ) on a particular textbox, for example textbox 34 labeled grills, which allows the user to navigate to another webpage displaying actual images, e.g. JPEG photos, of an array of grills 30 available for the particular vehicle 10 selected. The navigation process will be a function of underlying “links”, i.e. URLs associated with data processing resources 18 , 16 of the manufacturer of the particular component selected. Clicking on the textbox 34 will thus cause the user to navigate to a webpage hosted by data processing resource 18 , the webpage having a plurality of components displayed thereon. The user can then double click on the photo of a particular one of the components whereupon a link to a complete virtual or actual image of the component is made. The image is accompanied by text data indicating price, availability, manufacturer, and model no. of the selected grill 30 and is displayed in block 35 , after the user is automatically navigated back to the webpage 33 . If, for example the user selects grills 30 , then all grills 30 available for the selected vehicle are shown, including those available from the manufacturer of the selected vehicle 10 . If the grill 30 selected is available from an aftermarket manufacturer, then the user will be navigated to a resource 16 corresponding to the aftermarket manufacturer so that the selected grill image is displayed in block 35 , though this process can be transparent to the user as is known in the art. If the user decides to add a particular grill 30 , the image of the grill 30 may be double clicked which, after returning to webpage 33 and displaying the image of the component in block 35 , also causes a display of a virtual image of the vehicle 10 with the selected grill 30 . This action is repeated for every component to be selected until the user completes the customization process. It should be noted that all aspects of the vehicle configuration will be customizable using the web interface 33 as shown in FIG. 1 including, but not limited to, vehicle color, engine size, interior treatments, rims, tires, grills, hood ornaments, spoilers etc. Also, in the case of interior treatments, which includes dashboard and console configurations, materials, trim, and seat and floor mat colors, a simulation of the vehicle interior will be shown, the display being facilitated by way of a suitable CAD/CAM program configured in accordance with the specific requirements of the system of the invention. For example, if the user chooses a full complement of oval gauges, with walnut trim, black leather seats, and gold floor mats, the display in FIG. 1 will display, with sufficient resolution and detail, the selected vehicle interior with the layout as modified by the components chosen. The particular component under consideration (i.e., the most recent component selected) will be displayed in box 35 , with the text data as described above. [0035] The image displayed in box 35 will include the estimated delivery time to the manufacturer of the vehicle 10 of the selected component. It can be appreciated that the system 14 of the invention would require some cooperation of the vehicle manufacturer with manufacturers of various aftermarket components, including compatibility of image data associated with the aftermarket components as displayed on the computing resources 16 associated with the aftermarket manufacturers, as well as compensation agreements and any other arrangements to ensure the efficient delivery of a selected component as would be apparent to one of skill in the art. The delivery time of a selected component is viewable by the user of device 12 . Also, the user can click on a particular part of the vehicle 10 as displayed in FIG. 1 to display a particular component in box 35 . For example, the user can position the navigating device on wheels 32 to display a selected component for wheels 32 in box 35 . Thus, the user can view image and availability data of each component selected in box 35 , with the default image in box 35 being the last component added. If the user is not satisfied with the delivery date or the appearance of a selected component, she can choose another component. [0036] Referring now to FIG. 3 a flowchart illustrating the method of the invention is shown. It should be noted that while the invention is implemented as software on a computer server 18 in communication with an end user device 12 , the final result, in the event of a purchase, is a customized vehicle which may be an automobile, motorcycle, RV, SUV, or boat. Thus the invention is equally applicable to virtually any commodity which is modifiable by the addition or removal of components having an impact on the overall aesthetic or functional qualities of the commodity. The term block or step are used interchangeably and are considered equivalent. The first step of the invention after the initialization of a web browser on the user device 12 is the display of the web page provided by the, e.g., manufacturer of a vehicle to be purchased, which web page prompts the user for the type and model of the vehicle to be customized as shown in block 102 . Once the user (the term user hereinafter referring to the user of the end user device 12 unless otherwise indicated) enters the identifying information as described above, the interface or webpage 33 is shown allowing for the display of the vehicle, along with the components and options such as rims 32 , wheels, grills 30 , fabric options, vehicle color options, etc. as indicated in block 104 , and described in more detail above. Also, the MSRP of the vehicle is displayed, as well as the possible delivery date in text box 39 as will be discussed in more detail later. The image of the vehicle 10 is displayed, modified in accordance with the user's selection, updated in real time also as discussed above. [0037] Decision block 106 indicates the recurring steps of selecting and viewing (step 104 ) a component on or in a virtual image of the vehicle 10 ( FIG. 1 ) until all desired corrections or changes are made. Once the user is satisfied with the vehicle 10 and the selected components as displayed in FIG. 1 , he can click the seek icon 37 which causes server 21 to initialize a final search of all relevant databases, including those databases associated with server 21 and resources 16 , and advances the system to block 108 . The server 21 database will include all components available directly from the vehicle manufacturer. The resources 16 searched by the server 21 include, but are not limited to, databases of the vehicle manufacturer subsidiaries and manufacturers of aftermarket products as shown in block 108 , to ascertain that the selected components are available as indicated during step 104 . The updated, customized vehicle displayed at step 104 ( FIG. 1 ) includes a display of the price data (MSRP), which data includes the price for individual components available as discussed above. In block 110 , the system 18 will determine, and display in FIG. 1 ( 39 ), an approximate delivery date of the customized vehicle 10 . The determination of the delivery date will be based upon a number of factors including the shipping time and delivery of selected components, and the backlog of existing orders for vehicles 10 if any. If the delivery date shown in block 110 ( FIG. 1 ) is not acceptable, then the user may navigate back to the step shown in block 104 , to determine, inter alia, which components are delaying the delivery date and perhaps choosing other components using the method as described above, before progressing again to step 106 as shown in block 112 . A key aspect of the invention is that the vehicle 10 delivery date can be advanced by selecting more readily available aftermarket components if the user so desires, with the system allowing some transparency regarding which components are delaying the delivery date as discussed above. Otherwise, if the delivery date is acceptable, the customization process is complete and the user proceeds to step 114 by clicking on the next icon 41 ( FIG. 1 ) to view participating dealers and select the most convenient dealer location 43 , 45 as seen in FIG. 4 . The dealer location will be based upon the user's geographical location which may be determined by the user entering the log in/registration data as described above, the user selecting a maximum radius to limit the display of dealers to those within a reasonable distance if desired. The user may then proceed to the financing/documentation step as shown in block 116 , by clicking on next icon 51 as seen in FIG. 4 . During this step, displayed in FIG. 5 , the user is shown a number of financing options, along with the appropriate forms for proceeding with the application for financing process, which forms are accessed by clicking on a desired option 53 , 55 . The forms presented to the user at this point will be those prepared by the selected dealer, and the vehicle price (MSRP) will be adjusted in accordance with the dealer pricing schedule. Of course, the financing documentation will include all data relevant to the dealer, already filled in the appropriate boxes/columns, such as make, model, options, price, etc. The user of course fills in the necessary finance data, such as income, desired monthly payment, etc. After selecting a desired financing option and filling out the appropriate forms, the user may then either complete the transaction by printing out (block 117 ) and physically presenting the accumulated documentation to the dealer, which documentation will include information regarding the vehicle make and model, the components and relevant part numbers selected by the user, and the financing documentation as shown in block 116 , or the user can proceed with the fully online option as shown in block 118 , if available. It can be appreciated that not all manufacturers would desire such a complex transaction to be carried out online with the possibility of interne fraud so this option may only be available to a certain class of users as determined during the log-in and registration process, with the type of verification and documentation required being solely at the discretion of the manufacturer and/or dealer. If the end user device 12 is at the dealer's store location, then the user will be limited to the physical presentation option of step 116 . If the user proceeds with the online option of step 118 by clicking on next icon 61 , then an additional interface may be presented as shown in FIG. 6 at the option of the dealer selected, which interface will allow for some degree of negotiation of the price, and all allow for the secure entry of data necessary to complete the transaction. At this point, a representative of the selected dealer may be notified by the server 18 of an ongoing negotiation, and intervene to conduct an online or telephonic negotiation to both expedite and refine the process. Methods of notification may include an internet message (IM) directed to personnel designated for continuous monitoring of online negotiations. The system 14 thus allows the dealer to expedite and streamline sales initiated by an internet user, but only after the user 12 has indicated a high level of interest in purchasing the vehicle, to avoid burdening the dealer personnel with users that are merely price shopping. Of course, the system 14 can be used to alert the dealer as soon as the dealer has been selected by the user. [0038] Once the user has completed the customization, financing, and price negotiation, if any, a final date for delivery of the vehicle 10 is established, and the user then acquires the vehicle. [0039] It is to be understood that the provided illustrative examples are by no means exhaustive of the many possible uses for my invention. [0040] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.

An electronic system for the customization, visualization, integration, purchase, and acquisition of a vehicle from a vehicle manufacturer. The system is implemented on a computer server or equivalent device, where the server, operated by the manufacturer, is accessible over the internet via a suitable end-user operated computing device, the server generating a menu driven visual interface viewable on the computing device. The system allows for all aspects of a customized vehicle purchase to be performed by the user, substantially streamlining the selection and acquisition process. The system can be interfaced with third party parts databases, allowing for incorporation of parts from a variety of manufacturers.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 13/850,577, filed Mar. 26, 2013 (now U.S. Pat. No. ______), which is a continuation of U.S. patent Application No. 13/714,748, filed Dec. 14, 2012 (now U.S. Pat. No. 8,553,079), which is a continuation of U.S. patent application Ser. No. 12/700,055, filed Feb. 4, 2010, which is a continuation of U.S. patent application Ser. No. 10/866,191, filed Jun. 14, 2004, which is a continuation of U.S. patent application Ser. No. 09/433,297, filed Nov. 3, 1999 (now U.S. Pat. No. 6,750,848), which claims benefit of U.S. Provisional Application No. 60/107,652, filed Nov. 9, 1998. These applications are hereby incorporated by reference. REFERENCES TO RELATED APPLICATIONS BY THE INVENTORS [0002] U.S. patent application Ser. No. 09/138,339, filed Aug. 21, 1998. [0003] U.S. Provisional Application No. 60/056,639, filed Aug. 22, 1997. [0004] U.S. Provisional Application No. 60/059,561, filed Sep. 19, 1998. [0005] Man Machine Interfaces: Ser. No. 08/290,516, filed Aug. 15, 1994, and now U.S. Pat. No. 6,008,800. [0006] Touch TV and Other Man Machine Interfaces: Ser. No. 08/496,908, filed Jun. 29, 1995, and now U.S. Pat. No. 5,982,352. [0007] Systems for Occupant Position Sensing: Ser. No. 08/968,114, filed Nov. 12, 1997, now abandoned, which claims benefit of 60/031,256, filed Nov. 12, 1996. [0008] Target holes and corners: U.S. Ser. No. 08/203,603, filed Feb. 28, 1994, and Ser. No. 08/468,358 filed Jun. 6, 1995, now U.S. Pat. No. 5,956,417 and U.S. Pat. No. 6,044,183. [0009] Vision Target Based Assembly: U.S. Ser. No. 08/469,429, filed Jun. 6, 1995, now abandoned; Ser. No. 08/469,907, filed Jun. 6, 1995, now U.S. Pat. No. 6,301,763; Ser. No. 08/470,325, filed Jun. 6, 1995, now abandoned; and Ser. No. 08/466,294, filed Jun. 6, 1995, now abandoned. [0010] Picture Taking Method and Apparatus: Provisional Application No. 60/133,671, filed May 11, 1998. [0011] Methods and Apparatus for Man Machine Interfaces and Related Activity: Provisional Application No. 60/133,673 filed May 11, 1998. [0012] Camera Based Man-Machine Interfaces: Provisional Patent Application No. 60/142,777, filed Jul. 8, 1999. [0013] The copies of the disclosure of the above referenced applications are incorporated herein by reference. BACKGROUND OF THE INVENTION [0014] 1. Field of the Invention [0015] The invention relates to simple input devices for computers, particularly, but not necessarily, intended for use with 3-D graphically intensive activities, and operating by optically sensing object or human positions and/or orientations. The invention in many preferred embodiments, uses real time stereo photogrammetry using single or multiple TV cameras whose output is analyzed and used as input to a personal computer, typically to gather data concerning the 3D location of parts of, or objects held by, a person or persons. [0016] This continuation application seeks to provide further detail on useful embodiments for computing. One embodiment is a keyboard for a laptop computer (or stand alone keyboard for any computer) that incorporates digital TV cameras to look at points on, typically, the hand or the finger, or objects held in the hand of the user, which are used to input data to the computer. It may also or alternatively, look at the head of the user as well. [0017] Both hands or multiple fingers of each hand, or an object in one hand and fingers of the other can be simultaneously observed, as can alternate arrangements as desired. [0018] 2. Description of Related Art [0019] My referenced co-pending applications incorporated herein by reference discuss many prior art references in various pertinent fields, which form a background for this invention. BRIEF DESCRIPTION OF FIGURES [0020] FIG. 1 illustrates a laptop or other computer keyboard with cameras according to the invention located on the keyboard surface to observe objects such as fingers and hands overhead of the keyboard. [0021] FIG. 2 illustrates another keyboard embodiment using special datums or light sources such as LEDs. [0022] FIG. 3 illustrates a further finger detection system for laptop or other computer input. [0023] FIG. 4 illustrates learning, amusement, monitoring, and diagnostic methods and devices for the crib, playpen and the like. [0024] FIG. 5 illustrates a puzzle toy for young children having cut out wood characters according to the invention. [0025] FIG. 6 illustrates an improved handheld computer embodiment of the invention, in which the camera or cameras may be used to look at objects, screens and the like as well as look at the user along the lines of FIG. 1 . [0026] FIGS. 7A-B illustrate new methods for internet commerce and other activities involving remote operation with 3D virtual objects display. DESCRIPTION OF THE INVENTION [0027] FIG. 1 [0028] A laptop (or other) computer keyboard based embodiment is shown in FIG. 1 . In this case, a stereo pair of cameras 100 and 101 located on each side of the keyboard are used, desirably having cover windows 103 and 104 mounted flush with the keyboard surface 102 . The cameras are preferably pointed obliquely inward at angles Φ toward the center of the desired work volume 170 above the keyboard. In the case of cameras mounted at the rear of the keyboard (toward the display screen), these cameras are also inclined to point toward the user at an angle as well. [0029] Alternate camera locations may be used such as the positions of cameras 105 and 106 , on upper corners of screen housing 107 looking down at the top of the fingers (or hands, or objects in hand or in front of the cameras), or of cameras 108 and 109 shown. [0030] One of the referenced embodiments of the invention is to determine the pointing direction vector 160 of the user's finger (for example pointing at an object displayed on screen 107 ), or the position and orientation of an object held by the user. Alternatively, finger position data can be used to determine gestures such as pinch or grip, and other examples of relative juxtaposition of objects with respect to each other, as has been described in co-pending referenced applications. Positioning of an object or portions (such as hands or fingers of a doll) is also of use, though more for use with larger keyboards and displays. [0031] In one embodiment, shown in FIG. 2 , cameras such as 100 / 101 are used to simply look at the tip of a finger 201 (or thumb) of the user, or an object such as a ring 208 on the finger. Light from below, such as provided by single central light 122 can be used to illuminate the finger that typically looks bright under such illumination. [0032] It is also noted that the illumination is directed or concentrated in an area where the finger is typically located such as in work volume 170 . If the light is of sufficient spectral content, the natural flesh tone of the finger can be observed—and recognized by use of the color TV cameras 100 / 101 . [0033] As is typically the case, the region of the overlapping cameras viewing area is relatively isolated to the overlapping volumetric zone of their fields 170 shown due to focal lengths of their lenses and the angulation of the camera axes with respect to each other. This restricted overlap zone helps mitigate against unwanted matches in the two images due to information generated outside the zone of overlap. Thus there are no significant image matches found of other objects in the room, since the only flesh-toned object in the zone is typically the finger or fingers of the user. Or alternatively, for example, the user's hand or hands. Similarly objects or targets thereon can be distinguished by special colors or shapes. [0034] If desired, or required, motion of the fingers can be also used to further distinguish their presence vis-a-vis any static background. If for example, by subtraction of successive camera frames, the image of a particular object is determined to have moved it is determined that this is likely the object of potential interest which can be further analyzed directly to determine if is the object of interest. [0035] In case of obscuration of the fingers or objects in the hand, cameras in additional locations such as those mentioned above, can be used to solve for position if the view of one or more cameras is obscured. [0036] The use of cameras mounted on both the screen and the keyboard allows one to deal with obscurations that may occur and certain objects may or may not be advantageously delineated in one view or the other. [0037] In addition, it may be in many cases desirable to have a datum on the top of the finger as opposed to the bottom because on the bottom, it can get in the way of certain activities. In this case the sensors are required on the screen looking downward or in some other location such as off the computer entirely and located overhead has been noted in previous application. [0038] To determine finger location, a front end processor like that described in the target holes and corners co-pending application reference incorporated U.S. Ser. Nos. 08/203,603 and 08/468,358 can be used to also allow the finger shape as well as color to be detected. [0039] Finger gestures comprising a sequence of finger movements can also be detected by analyzing sequential image sets such as the motion of the finger, or one finger with respect to another such as in pinching something can be determined. Cameras 100 and 101 have been shown at the rear of the keyboard near the screen or at the front. They may mount in the middle of the keyboard or any other advantageous location. [0040] The cameras can also see one's fingers directly, to allow typing as now, but without the physical keys. One can type in space above the plane of the keyboard (or in this case plane of the cameras). This is useful for those applications where the keyboard of conventional style is too big (e.g., the hand held computer of FIG. 6 ). [0041] FIG. 2 [0042] It is also desirable for fast reliable operation to use retro-reflective materials and other materials to augment the contrast of objects used in the application. For example, a line target such as 200 can be worn on a finger 201 , and advantageously can be located if desired between two joints of the finger as shown. This allows the tip of the finger to be used to type on the keyboard without feeling unusual—the case perhaps with target material on tip of the finger. [0043] The line image detected by the camera can be provided also by a cylinder such as retroreflective cylinder 208 worn on the finger 201 which effectively becomes a line image in the field of view of each camera (assuming each camera is equipped with a sufficiently coaxial light source, typically one or more LEDs such as 210 and 211 ), can be used to solve easily using the line image pairs with the stereo cameras for the pointing direction of the finger that is often a desired result. The line, in the stereo pair of images provides the pointing direction of the finger, for example pointing at an object displayed on the screen 140 of the laptop computer 138 . [0044] FIG. 3 [0045] It is also possible to have light sources on the finger that can be utilized such as the 2 LED light sources shown in FIG. 3 . This can be used with either TV camera type sensors or with PSD type analog image position sensors as disclosed in references incorporated. [0046] In particular the ring mounted LED light sources 301 and 302 can be modulated at different frequencies that can be individually discerned by sensors imaging the sources on to a respective PSD detector. Alternatively, the sources can simply be turned on and off at different times such that the position of each point can be independently found allowing the pointing direction to be calculated from the LED point data gathered by the stereo pair of PSD based sensors. [0047] The “natural interface keyboard” here described can have cameras or other sensors located at the rear looking obliquely outward toward the front as well as inward so as to have their working volume overlap in the middle of the keyboard such as the nearly full volume over the keyboard area is accommodated. [0048] Clearly larger keyboards can have a larger working volume than one might have on a laptop. The pair of sensors used can be augmented with other sensors mounted on the screen housing. It is noted that the linked dimension afforded for calibration between the sensors located on the screen and those on the keyboard is provided by the laptop unitary construction. [0049] One can use angle sensing means such as a rotary encoder for the laptop screen tilt. Alternatively, cameras located on the screen can be used to image reference points on the keyboard as reference points to achieve this. This allows the calibration of the sensors mounted fixedly with respect to the screen with respect to the sensors and keyboard space below. It also allows one to use stereo pairs of sensors that are not in the horizontal direction (such as 101 / 102 ) but could for example be a camera sensor such as 100 on the keyboard coupled with one on the screen, such as 106 . [0050] Knowing the pointing angles of the two cameras with respect to one another allows one to solve for the 3D location of objects from the matching of the object image positions in the respective camera fields. [0051] As noted previously, it is also of interest to locate a line or cylinder type target on the finger between the first and second joints. This allows one to use the fingertip for the keyboard activity but by raising the finger up, it can be used as a line target capable of solving for the pointed direction for example. [0052] Alternatively one can use two point targets on the finger such as either retroreflective datums, colored datums such as rings or LED light sources that can also be used with PSD detectors which has also been noted in FIG. 2 . [0053] When using the cameras located for the purpose of stereo determination of the position of the fingers from their flesh tone images it is useful to follow the preprocessing capable of processing data obtained from the cameras in order to look for the finger. This can be done on both color basis and on the basis of shape as well as motion. [0054] In this invention, I have shown the use of not only cameras located on a screen looking downward or outward from the screen, but also cameras that can be used instead of or in combination with those on the screen placed essentially on the member on which the keyboard is incorporated. This allows essentially the keyboard to mounted cameras which are preferably mounted flush with the keyboard surface to be unobtrusive, and yet visually be able to see the users fingers, hands or objects held by the user and in some cases, the face of the user. [0055] This arrangement is also useful for 3D displays, for example where special synchronized glasses (e.g., the “Crystal Eyes” brand often used with Silicon Graphics work stations) are used to alternatively present right and left images to each eye. In this case the object may appear to be actually in the workspace 170 above the keyboard, and it may be manipulated by virtually grasping (pushing, pulling, etc.) it, as has been described in co-pending applications. [0056] FIG. 4 : Baby Learning and Monitoring System [0057] A baby's reaction to the mother (or father) and the mother's analysis of the baby's reaction is very important. There are many gestures of babies apparently indicated in child psychology as being quite indicative of various needs, wants, or feelings and emotions, etc. These gestures are typically made with the baby's hands. [0058] Today this is done and learned entirely by the mother being with the baby. However with an Electro-optical sensor based computer system, such as that described in co-pending applications located proximate to or even in the crib (for example), one can have the child's reactions recorded, not just in the sense of a video tape which would be too long and involved for most to use, but also in terms of the actual motions which could be computer recorded and analyzed also with the help of the mother as to what the baby's responses were. And such motions, combined with other audio and visual data can be very important to the baby's health, safety, and learning. [0059] Consider for example crib 400 with computer 408 having LCD monitor 410 and speaker 411 and camera system (single or stereo) 420 as shown, able to amuse or inform baby 430 , while at the same time recording (both visually, aurally, and in movement detected position data concerning parts of his body or objects such as rattles in his hand) his responses for any or all of the purposes of diagnosis of his state of being, remote transmission of his state, cues to various programs or images to display to him or broadcast to others, or the like. [0060] For one example, baby's motions could be used to signal a response from the TV either in the absence of the mother or with the mother watching on a remote channel. This can even be over the Internet if the mother is at work. [0061] For example, a comforting message could come up on the TV from the mother that could be prerecorded (or alternatively could actually be live with TV cameras in the mother's or father's workplace for example on a computer used by the parent) to tell the baby something reassuring or comfort the baby or whatever. Indeed the parent can be monitored using the invention and indicate something back or even control a teleoperater robotic device to give a small child something to eat or drink for example. The same applies to a disabled person. [0062] If the father or mother came up on the screen, the baby could wave at it, move its head or “talk” to it but the hand gestures may be the most important. [0063] If the mother knows what the baby is after, she can talk to baby or say something, or show something that the baby recognizes such as a doll. After a while, looking at this live one can then move to talking to the baby from some prerecorded data. [0064] What other things might we suppose? The baby for example knows to puts its hand on the mother's cheek to cause the mother to turn to it. The baby also learns some other reflexes when it is very young that it forgets when it gets older. Many of these reflexes are hand movements, and are important in communicating with the remote TV based mother representation, whether real via telepresense or from CD Rom or DVD disk (or other media, including information transmitted to the computer from afar) and for the learning of the baby's actions. [0065] Certainly just from the making the baby feel good point-of-view, it would seem like certain motherly (or fatherly, etc.) responses to certain baby actions in the form of words and images would be useful. This stops short of physical holding of the baby which is often needed, but could act as a stop gap to allow the parents to get another hour's sleep for example. [0066] As far as the baby touching things, I've discussed in other applications methods for realistic touch combined with images. This leads to a new form of touching crib mobiles that could contain video imaged and or be imaged themselves—plus if desired—touched in ways that would be far beyond any response that you could get from a normal mobile. [0067] For example, let us say there is a targeted (or otherwise TV observable) mobile 450 in the crib above the baby. Baby reaches up and touches a piece of the mobile which is sensed by the TV camera system (either from the baby's hand position, the mobile movement, or both, and a certain sound is called up by the computer, a musical note for example. Another piece of the mobile and another musical note. The mobile becomes a musical instrument for the baby that could play either notes or chords or complete passages, or any other desired programmed function. [0068] The baby can also signal things. The baby can signal using agitated movements would often mean that it's unhappy. This could be interpreted using learned movement signatures and artificial intelligence as needed by the computer to call for mother even if the baby wasn't crying. If the baby cries, that can be picked up by microphone 440 , recognized using a voice recognition system along the lines of that used in IBM Via Voice commercial product for example. And even the degree of crying can be analyzed to determine appropriate action. [0069] The computer could also be used to transmit information of this sort via the internet email to the mother who could even be at work. And until help arrives in the form of mother intervention or whatever, the computer could access a program that could display on a screen for the baby things that the baby likes and could try to soothe the baby through either images of familiar things, music or whatever. This could be useful at night when parents need sleep, and anything that would make the baby feel more comfortable would help the parents. [0070] It could also be used to allow the baby to input to the device. For example, if the baby was hungry, a picture of the bottle could be brought up on the screen. The baby then could yell for the bottle. Or if the baby needed his diaper changed, perhaps something reminiscent of that. If the baby reacts to such suggestions of his problem, this gives a lot more intelligence as to why he is crying and while mothers can generally tell right away, not everyone else can. In other words, this is pretty neat for babysitters and other members of the household so they can act more intelligently on the signals the baby is providing. [0071] Besides in the crib, the system as described can be used in conjunction with a playpen, hi-chair or other place of baby activity. [0072] As the child gets older, the invention can further be used also with more advanced activity with toys, and to take data from toy positions as well. For example, blocks, dolls, little cars, and moving toys even such as trikes, scooters, driveable toy cars and bikes with training wheels. [0073] The following figure illustrates the ability of the invention to learn, and thus to assist in the creation of toys and other things. [0074] FIG. 5 : Learning Puzzle Roy [0075] Disclosed in FIG. 5 is a puzzle toy 500 where woodcut animals such as bear 505 and lion 510 are pulled out with handle such as 511 . The child can show the animal to the camera and a computer 530 with TV camera (or cameras) 535 can recognize the shape as the animal, and provide a suitable image and sounds on screen 540 . [0076] Alternatively, and more simply, a target, or targets on the back of the animal can be used such as triangle 550 on the back of lion 511 . In either case the camera can solve for the 3D, and even 5 or 6D position and orientation of the animal object, and cause it to move accordingly on the screen as the child maneuvers it. The child can hold two animals, one in each hand and they can each be detected, even with a single camera, and be programmed in software to interact as the child wishes (or as he learns the program). [0077] This is clearly for very young children of two or three years of age. The toys have to be large so they can't be swallowed. [0078] With the invention in this manner, one can make a toy of virtually anything, for example a block. Just hold this block up, teach the computer/camera system the object and play using any program you might want to represent it and its actions. To make this block known to the system, the shape of the block, the color of the block or some code on the block can be determined. Any of those items could tell the camera which block it was, and most could give position and orientation if known. [0079] At that point, an image is called up from the computer representing that particular animal or whatever else the block is supposed to represent. Of course this can be changed in the computer to be a variety of things if this is something that is acceptable to the child. It could certainly be changed in size such as a small lion could grow into a large lion. The child could probably absorb that more than a lion changing into a giraffe for example since the block wouldn't correspond to that. The child can program or teach the system any of his blocks to be the animal he wants and that might be fun. [0080] For example, he or the child's parent could program a square to be a giraffe where as a triangle would be a lion. Maybe this could be an interesting way to get the child to learn his geometric shapes! [0081] Now the basic block held up in front of the camera system could be looked at just for what it is. As the child may move the thing toward or away from the camera system, one may get a rough sense of depth from the change in shape of the object. However this is not so easy as the object changes in shape due to any sort of rotations. [0082] Particularly interesting then is to also sense the rotations if the object so that the animal can actually move realistically in 3 Dimensions on the screen. And perhaps having the de-tuning of the shape of the movement so that the child's relatively jerky movements would not appear jerky on the screen or would not look so accentuated. Conversely of course, you can go the other way and accentuate the motions. [0083] This can, for example, be done with a line target around the edge of the object is often useful for providing position or orientation information to the TV camera based analysis software, and in making the object easier to see in reflective illumination. [0084] Aid to Speech Recognition [0085] The previous co-pending application entitled “Useful man machine interfaces and applications” referenced above, discussed the use of persons movements or positions to aid in recognizing the voice spoken by the person. [0086] In one instance, this can be achieved by simply using ones hand to indicate to the camera system of the computer that the voice recognition should start (or stop, or any other function, such as a paragraph or sentence end, etc.). [0087] Another example is to use the camera system of the invention to determine the location of the persons head (or other part), from which one can instruct a computer to preferentially evaluate the sound field in phase and amplitude of two or more spaced microphones to listen from that location—thus aiding the pickup of speech—which often times is not able to be heard well enough for computer based automatic speech recognition to occur. [0088] Digital Interactive TV [0089] As you watch TV, data can be taken from the camera system of the invention and transmitted back to the source of programming. This could include voting on a given proposition by raising your hand for example, with your hand indication transmitted. Or you could hold up 3 fingers, and the count of fingers transmitted. Or in a more extreme case, your position, or the position of an object or portion thereof could be transmitted—for example you could buy a coded object—whose code would be transmitted to indicate that you personally (having been pre-registered) had transmitted a certain packet of data. If the programming source can transmit individually to you (not possible today, but forecast for the future), then much more is possible. The actual image and voice can respond using the invention to positions and orientations of persons or objects in the room—just as in the case of prerecorded data—or one to one internet connections. This allows group activity as well. [0091] In the extreme case, full video is transmitted in both directions and total interaction of users and programming sources and each other becomes possible. [0092] An interim possibility using the invention is to have a program broadcast to many, which shifts to prerecorded DVD disc or the like driving a local image, say when your hand input causes a signal to be activated. [0093] Handwriting Authentication [0094] A referenced co-pending application illustrated the use of the invention to track the position of a pencil in three dimensional space such that the point at which the user intends the writing point to be at, can be identified and therefore used to input information, such as the intended script. [0095] As herein disclosed, this part of the invention can also be used for the purpose of determining whether or not a given person's handwriting or signature is correct. [0096] For example, consider authentication of an Internet commercial transaction. In this case, the user simply writes his name or address and the invention is used to look at the movements of his writing instrument and determine from that whether or not the signature is authentic. (A movement of one or more of his body parts might also or alternatively be employed). For example a series of frames of datum location on his pen can be taken, to determine one or more positions on it as a function of time, even to include calculating of its pointing direction, from a determined knowledge in three axes of two points along the line of the pen axis. In this case a particular pointing vector sequence “signature” would be learned for this person, and compared to later signatures. [0097] What is anticipated here is that in order to add what you might call the confirming degree of authenticity to the signature, it may not be necessary to track the signature completely. Rather one might only determine that certain aspects of the movement of the pencil are the authentic ones. One could have people write using any kind of movement, not just their signature having their name. The fact is that people are mostly used to writing their name and it would be assumed that that would be it. However, it could well be that the computer asks the user to write something else that they would then write and that particular thing would be stored in the memory. [0098] Optionally, one's voice could be recognized in conjunction with the motion signature to add further confirmation. [0099] This type of ability for the computer system at the other end of the Internet to query a writer to write a specific thing in a random fashion adds a degree of cryptographic capacity to the invention. In other words, if I can store the movements in my hand to write different things, then clearly this has some value. [0100] The important thing though is that some sort of representation of the movements of the pencil or other instrument can be detected using the invention and transmitted. [0101] FIG. 6 : Hand Held Computer [0102] FIG. 6 illustrates an improved handheld computer embodiment of the invention. For example, FIG. 8 of the provisional application referenced above entitled “camera based man machine interfaces and applications” illustrates a basic hand held device and which is a phone, or a computer or a combination thereof, or alternatively to being hand held, can be a wearable computer for example on one's wrist. [0103] In this embodiment, we further disclose the use of this device as a computer, with a major improvement being the incorporation of a camera of the device optionally in a position to look at the user, or an object held by the user—along the lines of FIG. 1 of the instant disclosure for example. [0104] Consider hand held computer 901 of FIG. 6 , incorporating a camera 902 which can optionally be rotated about axis 905 so as to look at the user or a portion thereof such as finger 906 , or at objects at which it is pointed. Optionally, and often desirably, a stereo pair of cameras to further include camera 910 can also be used. It too may rotate, as desired. Alternatively fixed cameras can be used as in FIG. 1 , and FIG. 8 of the referenced co-pending application, when physical rotation is not desired, for ruggedness, ease of use, or other reasons (noting that fixed cameras have fixed fields of view, which limit versatility in some cases). [0105] When aimed at the user, as shown, it can be used, for example, to view and obtain images of: [0106] Ones self-facial expression etc., also for image reasons, id etc., combined effect. [0107] Ones fingers (any or all), one finger to other and the like. This in turn allows conversing with the computer in a form of sign language which can replace the keyboard of a conventional computer. [0108] One or more objects in one's hand. Includes a pencil or pen, and thus can be used rather than having a special touch screen and pencil if the pencil itself is tracked as disclosed in the above figure. It also allows small children to use the device, and those who cannot hold an ordinary stylus. [0109] One's Gestures. [0110] The camera 902 (and 910 if used, and if desired), can also be optionally rotated and used to viewpoints in space ahead of the device, as shown in dotted lines 902 a. In this position for example it can be used for the purposes described in the previous application. It can also be used to observe or point at (using optional laser pointer 930 ) points such as 935 on a wall, or a mounted LCD or projection display such as 940 on a wall or elsewhere such as on the back of an airline seat. [0111] With this feature of the invention, there is no requirement to carry a computer display with you as with a infrared connection (not shown) such as known in the art one can also transmit all normal control information to the display control computer 951 . As displays become ubiquitous, this makes increasing sense—otherwise the displays get bigger the computers smaller trend doesn't make sense if they need to be dragged around together. As one walks into a room, one uses the display or displays in that room (which might themselves be interconnected). [0112] The camera unit 902 can sense the location of the display in space relative to the handheld computer, using for example the four points 955 - 958 on the corners of the display as references. This allows the handheld device to become an accurate pointer for objects displayed on the screen, including control icons. And it allows the objects on the screen to be sensed directly by the camera—if one does not have the capability to spatially synchronize and coordinate the display driver with the handheld computer. [0113] The camera can also be used to see gestures of others, as well as the user, and to acquire raw video images of objects in its field. [0114] A reverse situation also exists where the cameras can be on the wall mounted display, such as cameras 980 and 981 can be used to look at the handheld computer module 901 and determine its position and orientation relative to the display. [0115] Note that a camera such as 902 , looking at you the user, if attached to hand held unit, always has reference frame of that unit. If one works with a screen on a wall, one can aim the handheld unit with camera at it, and determine its reference frame to the handheld unit. Also can have two cameras operating together, one looking at wall thing, other at you (as 902 and 902 a ) in this manner, one can dynamically compare ref frames of the display to the human input means in determining display parameters. This can be done in real time, and if so one can actually wave the handheld unit around while still imputing accurate data to the display using ones fingers, objects or whatever. [0116] Use of a laser pointer such as 930 incorporated into the handheld unit has also been disclosed in the referenced co-pending applications. For example, a camera on the hand held computer unit such as 902 viewing in direction 902 a would look at laser spot such as 990 (which might or might not have come from the computers own laser pointer 930 ) on the wall display say, and recognized by color and size/shape reference to edge of screen, and to projected spots on screen. [0117] FIGS. 7A-B : Internet and Other Remote Applications [0118] FIG. 7A illustrates new methods for internet commerce and other activities involving remote operation with 3D virtual objects displayed on a screen. This application also illustrates the ability of the invention to prevent computer vision eye strain. [0119] Let us first consider the operation of the invention over the internet as it exists today in highly bandwidth limited form dependent on ordinary phone lines for the most part. In this case it is highly desirable to transmit just the locations or pointing vectors of portions (typically determined by stereo photo-grammetry of the invention) of human users or objects associated therewith to a remote location, to allow the remote computer 10 to modify the image or sound transmitted back to the user. [0120] Another issue is the internet time delay, which can exist in varying degrees, and is more noticeable, the higher resolution of the imagery transmitted. In this case, a preferred arrangement is to have real time transmission of minimal position and vector data (using no more bandwidth than voice), and to transmit back to the user, quasi stationary images at good resolution. Transmission of low resolution near real time images common in internet telephony today, does not convey the natural feeling desired for many commercial applications to now be discussed. As bandwidth becomes more plentiful these restrictions are eased. [0121] Let us consider the problem posed of getting information from the internet of today. A user 1000 can go to a virtual library displayed on screen 1001 controlled by computer 1002 where one sees a group 1010 of books on stacks. Using the invention as described herein and incorporated referenced applications to determine my hand and finger locations, I the user, can point at a book such as 1014 in a computer sensed manner, or even reach out and “grab” a book, such as 1020 (dotted lines) apparently generated in 3D in front of me. [0122] My pointing, or my reach and grab is in real time, and the vector (such as the pointing direction of ones finger at the book on the screen, or the position and orientation closing vectors of one's forefinger and thumb to grab the 3D image 1020 of the book) indicating the book in question created is transmitted back by internet means to the remote computer 1030 which determines that I have grabbed the book entitled War and Peace from the virtual shelf. A picture of the book coming off the shelf is then generated using fast 3D graphical imagery such as the Merlin VR package available today from Digital Immersion company of Sudbury, Ontario. This picture (and the original picture of the books on the shelves) can be retransmitted over the internet at low resolution (but sufficient speed) to give a feeling of immediacy to the user. Or alternatively, the imagery can be generated locally at higher resolution using the software package resident in the local computer 1002 which receives key commands from the distant computer 1030 . [0123] After the book has been “received” by the user, it then can be opened automatically to the cover page for example under control of the computer, or the users 10 hands can pretend to open it, and the sensed hands instruct the remote (or local, depending on version) computer to do so. A surrogate book such as 1040 can also be used to give the user a tactile feel of a book, even though the real book in questions pages will be viewed on the display screen 1001 . One difference to this could be if the screen 1001 depicting the books were life size, like real stacks. Then one might wish to go over to a surrogate book incorporating a separate display screen—just as one would in a real library, go to a reading table after removing a book from a stack. [0124] Net Grocery stores have already appeared, and similar applications concern picking groceries off of the shelf of a virtual supermarket, and filling ones shopping cart. For that matter, any store where it is desired to show the merchandise in the very manner people are accustomed to seeing it, namely on shelves or racks, generally as one walks down an aisle, or fumbles through a rack of clothes for example. In each case, the invention, which also can optionally use voice input, as if to talk to a clothing sales person, can be used to monitor the person's positions and gestures. [0125] The invention in this mode can also be used to allow one to peruse much larger objects. For example, to buy a car (or walk through a house, say) over the internet, one can lift the hood, look inside, etc., all by using the invention to monitor the 3D position of your head or hands and move the image of the car presented accordingly. If the image is presented substantially life-size, then one can be monitored as one physically walks around the car in one's room say, with the image changing accordingly. In other words just as today. [0126] Note that while the image can be apparently life-size using virtual reality glasses, the natural movements one is accustomed to in buying a car are not present. This invention makes such a natural situation possible (though it can also be used with such glasses as well). [0127] It is noted that the invention also comprehends adding a force based function to a feedback to your hands, such that it feels like you lifted the hood, or grabbed the book, say. For this purpose holding a surrogate object as described in co-pending applications could be useful, in this case providing force feedback to the object. [0128] If one looks at internet commerce today, some big applications have turned out 10 to be clothes and books. Clothes are by far the largest expenditure item, and let's look closer at this. [0129] Consider too a virtual mannequin, which can also have measurements of a remote shopper. For example, consider diagram 78 , where a woman's measurements are inputted by known means such as a keyboard 1050 over the internet to a CAD program in computer 1055 , which creates on display screen 1056 a 3D representation of a mannequin 1059 having the woman's shape in the home computer 1060 . As she selects a dress 1065 to try on, the dress which let's say comes in 10 sizes, 5 to 15, is virtually “tried on” the virtual mannequin and the woman 1070 looks at the screen 1056 and determines the fit of a standard size 12 dress. She can rapidly select larger or smaller sizes and decide which she thinks looks and/or fits better. [0130] Optionally, she can signal to the computer to rotate the image in any direction, and can look at it from different angles up or down as well, simply doing a rotation in the computer. This signaling can be conventional using for example a mouse, or can be using TV based sensing aspects of the invention such as employing camera 1070 also as shown in FIG. 1 for example. In another such case, she can reach out with her finger 1075 for example, and push or pull in a virtual manner the material, using the camera to sense the direction of her finger. Or she can touch herself at the points where the material should be taken up or let out, with the camera system sensing the locations of touch (typically requiring at least a stereo pair of cameras or other electro-optical system capable of determining where her fingertip is in 3D space. Note that a surrogate for the tried on dress in this case, could be the dress she has on, which is touched in the location desired on the displayed dress. [0131] The standard size dress can then be altered and shipped to her, or the requisite modifications can be made in the CAD program, and a special dress cut out and sewed which would fit better. [0132] A person can also use her hands via the TV cameras of the invention to determine hand location relative to the display to take clothes off a virtual manikin which could have a representation of any person real or imaginary. Alternatively she can remotely reach out using the invention to a virtual rack of clothes such as 1090 , take an object off the rack, and put it on the manikin. This is particularly natural in near life-size representation, just like being in a store or other venue. This ability of the invention to bring real life experience to computer shopping and other activity that is a major advantage. [0133] The user can also feel the texture of the cloth if suitable haptic devices are 15 available to the user, which can be activated remotely by the virtual clothing program, or other type of program. [0134] Modifications of the invention herein disclosed will occur to persons skilled in the art, and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.

A method for enhancing a well-being of a small child or baby utilizes at least one TV camera positioned to observe one or more points on the child or an object associated with the child. Signals from the TV camera are outputted to a computer, which analyzes the output signals to determine a position or movement of the child or child associated object. The determined position or movement is then compared to preprogrammed criteria in the computer to determine a correlation or importance, and thereby to provide data to the child.

BACKGROUND OF THE INVENTION The present invention relates in general to a variable height support apparatus and more specifically to a variable height support apparatus for use in combination with a solid object dispenser such as a pill or capsule dispenser. The variable height support of this invention is an improvement in that it allows a dispenser for filling blister packs with pills or capsules to be easily modified to dispense pills or capsules of various thicknesses without reconfiguration or modification of the dispenser apparatus. With the conventional pill or capsule card filling apparatus it is generally necessary to modify or reconfigure the apparatus whenever changing the size, and particularly the thickness of the pills or capsules to be placed in the receptacle portions of the conventional pill or capsule card or blister pack. Blister packs, consisting of a molded semi-rigid base covered and sealed by a rupturable material, are commonly used for packaging pills and capsules. Blister packs are used both by pharmaceutical companies which manufacture the drugs and package them in blister packs, and by smaller health care facilities which use the blister packs for packaging individual doses. These blister packs are also manufactured by companies in the business of providing unfilled blister packs for filling by third parties. Many conventional dispensers are manufactured to dispense only one size or shape of pill or capsule. Such dispensers are commonly used by pharmaceutical companies which are geared to produce the filled pill or capsule cards or blister packages in large quantities for a particular pill or capsule. However, for smaller manufacturers or health care facilities it is desirable to be able to produce and fill the cards or blister packages with pills or capsules of various sizes and shapes and use a minimum number of different dispenser. A single, easily modified dispenser is particularly suited to this portion of the industry. Conventional dispensers are available which can be modified to dispense pills or capsules of varying shapes and sizes. However, these conventional dispensers do not include the improvements included in the present invention as described more fully herein and illustrated in the accompanying drawings. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a pill or capsule dispensing support structure in which the height of pill or capsule guiding or transfer member of the structure is easily varied. Another object of the present invention is to provide a support structure in which the height of the aforementioned structure is varied in 1/32" units. A further object of the present invention is to provide a variable height support structure which is economically constructed with a minimum of parts to avoid expensive repair or replacement. Still another object of the present invention is to provide a variable height support structure which is suitable for use in combination with a solid object dispenser. Still a further object of the present invention is to provide a dispenser capable of filling blister packs with pills or capsules of various thicknesses by simply turning a knob. To accomplish the foregoing and other objects of this invention there is provided a variable height support structure for use in combination with a dispenser. The variable height support structure comprises a work surface supported by an asymmetrical cam, the cam and corresponding axle being supported by a pillow block. The axle protrudes beyond the support structure and includes an end knob to facilitate turning. When the knob is turned, a different portion of the asymmetric cams are presented to their respective contact portions of the work surface, resulting in movement of the work surface up or down. The cams are preferably designed to move the work surface in increments of 1/32", corresponding to the standard variation in pill or capsule thickness. The cams are held in place at the stated increments by an indexing device comprising a spring-loaded ball bearing mounted within the pillow block and semi-spherical recesses on the cam face. The work surface is held in level vertical alignment with the dispenser by telescoping support members at the corners of the structure. When used with a dispenser, the height of the work surface is adjusted to correspond to the thickness of the pill or capsule being dispensed. A conventional paddle containing the blister packs to be filled is inserted into the structure and supported by the work surface. Once a blister pack is filled, then the paddle is used to move the blister pack to a heat sealing device. The dispenser device includes a bin for holding the bulk pills or capsules to be dispensed and rotating brushes to keep the pills in motion. The pills or capsules are swept by the brushes through apertures or openings in a stationary plate which forms the base of the bin. A spring-loaded shuttle plate which has openings corresponding to the size or thickness and shape of the pill or capsule is positioned underneath the apertures of openings in the stationary plate such that the pills or capsules fall into the openings. The shuttle plate then moves horizontally until the openings are aligned with apertures in a dispensing plate located beneath the shuttle plate. The dispensing plate includes apertures which are selected to correspond to the shape of the pill or capsule being dispensed. These apertures in the dispensing plate are aligned with the openings in the blister packs. It will be understood that the number of apertures and their arrangement or pattern in the dispensing plate will vary depending upon the number of receptacles and their arrangement in the receiving blister pack. The blister packs are held in position by a paddle plate. The pills or capsules drop through the dispensing plate and into the blister packs. The paddle with the now filled blister package is removed and replaced with an unfilled blister pack or another paddle with an unfilled blister pack is placed in position within the apparatus of the present invention. These and other objects and features of the present invention will be better understood and appreciated from the following detailed description of preferred embodiments thereof, selected for purposes of illustration and shown in the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the support structure of the present invention in combination with a solid object dispenser; FIG. 2 is a perspective view of the support structure of FIG. 1; FIG. 3 is a plan view of the support structure FIG. 2 with the work surface in dashed lines to show the cam and axle which vary the height of the work surface; FIG. 4 is a cross section of the structure of FIG. 2 taken along line 4--4 in FIG. 2; FIG. 5 is a front elevation of the structure of FIG. 2 with the work surface in its lowered position; FIG. 6 is a front elevation of the structure of FIG. 2 with the work surface in its raised position; FIG. 7 is a front perspective view of the cam assembly; FIG. 8 is a rear perspective view of the cam assembly illustrating the indexing device recesses on the cam face; FIG. 9 is a cross sectional view of the cam assembly showing a spring-loaded ball-bearing assembly; FIG. 10 is a plan view further illustrating the shuttle plate spring device and the dispenser surfaces; FIGS. 11 and 12 are plan views of apertured stationary plates located below the bin used in the dispenser of FIG. 1, including FIG. 11 illustrating a stationary plate having elongated slots for use in filling a conventional 30 or 31 pill or capsule blister package and FIG. 12 illustrating a stationary plate having apertures or openings arranged for filling a conventional 90 pill or capsule blister pack; FIGS. 13, 14 and 15 are plan views of the shuttle apertured plate openings, used in the dispenser of the present invention depicted in FIG. 1 with FIG. 13 illustrating the pill or capsule shaped aperture for filling a conventional 30 pill or capsule blister package, FIG. 14 illustrating an apertured plate for filling a conventional blister package with 90 relatively small pills or capsules, and FIG. 15 illustrating an apertured plate for filling a conventional blister package with 90 relatively larger sized pills or capsules; FIG. 16, 17 and 18 are plan views of a plurality of dispensing plates used in the dispenser shown in FIG. 1, wherein FIG. 16 illustrates elongated slots or openings for filling a conventional blister package with 30 or 31 pills or capsules, and FIG. 17 and FIG. 18 illustrate apertured plates for dispensing either 90 relatively small or relatively larger pills or capsules; FIG. 19 is a typical end view of the dispensing plate illustrating one embodiment of a shoulder arrangement on the sides of the dispensing plate in which the shoulder facilitates the insertion of the dispensing plate into the supporting frame member; and FIG. 20 illustrates a view of a blister pack paddle used in concert with the other plates by an operator of the dispenser structure and supported by the dispenser structure of FIG. 1. DETAILED DESCRIPTION Referring now to the drawings there is shown a preferred embodiment for the variable height support structure for the dispenser of this invention. The support structure is described in connection with a solid object dispenser, more particularly a dispenser for dispensing pills or capsules into blister packs. The support structure allows variation of the height of a work surface by use of asymmetric cams supporting the work surface. As the axle bearing the cams is turned, a portion of the cam having a different radius is presented to the work surface. The variation in cam radius results in a variation of the work surface height. The support structure of the present invention is particularly adapted for use with a pill or capsule dispenser. The location of the adjustable work surface that supports the dispenser plate is determined so as to allow the blister packs to be filled efficiently. It will be understood that the vertical location of the work relative to the shuttle plate surface can be changed as required as the thickness, shape or size of the pill or capsule being dispensed requires. The support structure of the present invention allows the work surface height to be adjusted in 1/32" increments by turning the axle-mounted knob. This obviates the need to completely disassemble or substantially reconfigure the dispenser to accommodate pills or capsules of varying thicknesses. The drawings show a preferred embodiment of the variable height support structure generally designated 10 in combination with a solid object dispenser generally designated 12 in FIG. 1. The presently preferred dispenser 12 has a dispenser base 17 in which the support structure 10 is housed. Base 17 includes a U-shaped cover portion 14 with one or more moveable tabs 15. The cover 14 supports a circular collar 16 which acts as a bin to hold a pill, capsule, pills or capsules to be dispensed. The tabs 15 hold the collar 16 in place. Mixer rods 18 having brushes 20 rotate to move and mix the pill, capsules, pills or capsules within the collar bin 16 with the rotating brushes. The rods 18 are rotated by a motor 22, and the rotation speed is controlled by the user through a selector 24. It will be understood that a motor driven brush arrangement of this type is conventional. As shown more clearly in FIG. 10, the U-shaped cover 14 has a recessed ledge 82 around its inner perimeter. The ledge 82 further includes two notches 84 and 86 located preferably at the mid-point along each of the "legs" of the U-shaped cover 14. A spring device 88 is mounted on the base portion of the cover 14 and extends horizontally over the recessed ledge 82. The support structure 10 is shown in more detail in FIG. 2 where the front face of dispenser base 17 has been removed. Structure 10 includes a work surface 28 which is framed by a U-shaped upwardly extending portion 26. Extending inwardly from the top of the U-shaped extension portion 26 is a second framing portion 90. The work surface 28 is preferably retained in level alignment by telescoping alignment members generally designated 29 located at the four corners of work surface 28. The alignment members 29 include a guide base 30, an inner telescoping member 32 and an outer telescoping member 34. The alignment members 29 are mounted on a base 36. It will be understood that other alignment arrangements are readily substituted for that shown with the preferred embodiment. The work surface 28 rests on the asymmetric cams 40, 41. The work surface 28 is shown in dashed lines in FIG. 3 to illustrate and clarify the location of the cam structure. It will be understood that the actual shape of the cam portion of the cam structure may be altered in the event that more than the 1/4" inch adjustment is required. This also underscores the fact that the present invention is not limited to the dispensing of pills or capsules in order to fill blister packs for later dispensing. The cams and the corresponding axle 42 are preferably supported by a pillow block 44 mounted to the base 36. A portion of the axle 42 extends beyond the structure 10 and includes a handle or a knob 46 to allow a user to turn the axle 42 and therefore the cams 40, 41. These cams 40, 41 and the axle 42 construction is shown in cross section in FIG. 4. The cams 40, 41 in the illustrated embodiment are asymmetric in shape. In the presently preferred embodiment one quadrant of both of the cams 40, 41 have a gradually increasing radius, the radius at its longest point being 1/4" longer than at its shortest point. The knob 46 turns the cams so that the radius of cams 40, 41 presented to the work surface increases in discreet 1/32" increments. This corresponds to the industry standard thicknesses of pills and capsules. These increments are accomplished by an indexing device as shown in FIG. 8 and FIG. 9. The rear cam 41 preferably includes semi-spherical recesses on the rear face of the cam. The portion of the corresponding pillow block adjacent to the cam face or the rear cam includes a spring-loaded ball bearing sized correspondingly to fit within the recesses on the cam face. As the knob 46 turns the cam 41, the ball-bearing 100 exerts pressure on the cam face. As a cam recess 94 is presented to the ball bearing 100, the spring 104 forces the ball-bearing 100 into the recess 94, "locking" the cam in position. By turning the knob 46 again, the force applied forces the ball bearing 100 back out of the recess 94. The ball bearing 100 then presses against the cam face until another recess 94 is presented. The nine cam recesses are located in relation to the cam and spring-loaded ball bearing so that each "locked" position corresponds to a 1/32" variation in the cam radius being presented to the work surface. FIG. 5 shows the cams 40, 41 positioned so that the shortest radius is presented to and supports work surface 28 so that the work surface 28 is in it lowest position. FIG. 6 shows the cams 40, 41 positioned so that the longest radius is presented to and supports the work surface 28 so that the work surface 28 is in its uppermost position. In use, the preferred combination dispenser 12 and the support structure 10 includes a desired number of replaceable plates and four replaceable plates are illustrated, each selected for a particular application. The uppermost plate 50, shown in FIGS. 11 and 12, as preferred for the described embodiment, is octagonal and forms the base of the bin 16. Plate 50 includes one or more apertures 52 through which the pill, pills, capsules or pills are swept by the rotating brushes 20. FIG. 11 illustrates a plate 50 with apertures 52 for ultimately dispensing pills or capsules into blister packages of either thirty (30) or thirty-one (31) openings. FIG. 12 shows a plate for use when the blister package has ninety (90) pills or capsules. It will be understood by one skilled in the art that the plate 50 is readily modified for use with the desired blister packages. A shuttle plate 64 shown in FIG. 13, FIG. 14 and FIG. 15 has openings 66 generally corresponding to the size and/or thickness of the pills or capsules to be dispensed. FIG. 13 generally illustrates a shuttle plate 64 used when filling blister packages of thirty (30) pills or capsules. It will be understood that this shuttle plate can be further modified to add another opening for use when filling blister packages of thirty-one (31) pills or capsules. FIG. 14 generally illustrates a shuttle plate 64 for use in filling blister packages of ninety (90) pills or capsules. FIG. 15 generally illustrates another embodiment of a shuttle plate 64 for use when filling blister packages of ninety (90) pills or capsules. The shuttle plate 64 includes projections or ears 70 which fit into receiving notches 84, 86 of the recessed ledge 82. The projections or ears are of a width sufficiently less than the notches 84, 86 so as to allow movement of the shuttle plate 64 in a front-to-back horizontal direction. A dispensing plate 56, shown in FIGS. 16, 17 and 18, has apertures 58 corresponding generally to the shape of the pills or capsules being dispensed. The plate 56 of FIG. 16 is used when dispensing pills or capsules into blister packages of either thirty (30) or thirty-one (31) count, while the dispensing plates illustrated in FIGS. 17 and 18 are shown to illustrate the dispensing plates used when dispensing relatively smaller and larger pills or capsules into ninety (90) count blister packages. Each dispensing plate 56 preferably includes a shoulder portion 92 along opposing outer side edges as generally illustrated in FIG. 19. When assembled the upper horizontal portion of each of the shoulder portions 92 are intended to rest on framing portion 90. This arrangement is one preferred embodiment for maintaining the desired alignment. It will be understood that other alignment arrangements are possible. It will be understood from filling conventional blister packages or cards with conventional filling devices that the shape of the apertures of this and the other plates may vary without effecting the scope of the present invention. It will be further understood that it would not be possible to illustrate every combination of number and size of holes. A particular arrangement can readily be formed when the size and number of pills or capsules and the blister package or card arrangement is known. Thus, one skilled in the art will now realize how the present invention can be readily adapted for as yet unknown pill or capsule size and number. The fourth plate is a conventional paddle 76 as shown in FIG. 20. The paddle 76 supports a blister pack 78, including one or more molded blister package recesses 30 to be filled. The plates are assembled as follows. Each blister pack 78 to be filled is positioned on its respective paddle 76 and the paddle is inserted. The paddle 76 is supported by the adjustable height work surface 28 of structure 10. The dispensing plate 56 is positioned above the paddle 76, with its shoulders 92 resting in the notches 92 of framing portion 90. The height of the support structure 10 is then adjusted as described below to correspond to the thickness of the pills or capsules to be dispensed. The shuttle plate 64 is positioned above the dispenser plate 56. The spring device 88 is mounted relative to the recessed ledge 82 and is depressed as the shuttle plate 64 is moved into place. The projections 70 are aligned with and fit into the notches 96 defined by the recessed ledge 82. When the force used to depress the spring device 88 is released, the bias of the spring device 88 forces the shuttle plate 64 back toward the front of the dispenser 12. The movement or displacement of the shuttle plate 64 is limited by the interference between the edges of the notches 96 and the projections 70 located in the notches. The upper plate 50 is then mounted on the U-shaped cover surface 14, between the cover surface 14 and the bin 16 which is held in place by tabs 15. To dispense pills or capsules, the appropriate plates form a group of available plates that are selected and assembled as previously described. The distance between the work surface 28 supporting the dispensing plate 56 and the shuttle plate 64 is then adjusted to allow for the thickness of the plates and the size and shape of the pills or capsules being dispensed. Without the aforementioned adjustment, the thickness of the particular adjacent plates chosen for the job and the thickness and/or shape and/or size of the pills or capsules intended to be dispensed could interfere with or even prevent the intended dispensing and filling of blister packages. Furthermore, this vertical height adjustment allows the apparatus of the present invention to be used for the same count but different size and/or shape pills or capsules to be dispensed with only the vertical height adjusted as taught herein. The height of the support structure 10 is adjusted by turning the knob 46 on axle 42, the 1/32" increments in the height of work surface 28 corresponding to the standard variation in pill or capsule thickness. It will be understood that other increments and total adjustment may vary depending upon the application in which the present invention is used. The bulk volume of the object to be dispensed is located in the collar bin 16. The rotation speed of the mixing rods 18 and brushes 20 is then selected when the mixing motor is turned on. The speed of the motor and brushes may be changed during the process if necessary to effect the movement of the pills or capsules within the bin 16. The brushes then sweep the pills or capsules over the apertures or openings of the first plate 50, and gravity acts on the pills or capsules which then fall through the apertures 52 and into the apertures or openings 66 of the shuttle plate 64 when the shuttle plate is in a receiving position. The shuttle plate 64 is then moved by applying a force against the spring mechanism. When the shuttle plate openings 66 are in vertical alignment with the dispensing plate 56 and its openings or apertures 58, then the pills or capsules fall through the dispensing plate 56 and into the molded recesses 30 of the blister package 78. The shuttle plate is then allowed to move back to its original biased position by the spring device. The filled blister packages 78 in the paddle 76 are replaced with another un-filled blister packages 78, which can be accomplished by either replacing the blister package or the entire paddle 76 and blister package combination. A cover 80 is heat sealed over the blister package to complete the process.* This is a brief summary of the operation of conventional dispensing apparatus as well as the apparatus of the present invention. The operation of the present invention is described below. When a pill or capsule of a differing shape or thickness is to be dispensed, the appropriate plates are inserted and the work surface height adjusted correspondingly. The ability to adjust the height of the work surface as shown and described herein provides an efficient and time saving manner in which the pills or capsules of varying thicknesses and shapes are allowed to be dispensed by the same machine without completely dismantling or extensively modifying the dispenser 10. From the foregoing description those skilled in the art will appreciate that all of the objects of the present invention are realized. A support structure is provided in which the height of the structure is easily varied. For the application disclosed herein the structure provides a surface work height that can be varied in 1/32" increments. The structure provided uses a minimum of parts, making the structure economical to produce and maintain. The structure is suitable for use in combination with a solid object dispenser, and thereby provides a dispenser capable of being modified to dispense objects of various sizes and shapes without disassembly of the dispenser. When used in combination with a pill or capsule dispenser, the structure provides a dispenser capable of filling blister packs with pills or capsules of varying thicknesses by simply turning a knob. While a specific embodiment has been shown and described, many variations are possible. The dispensing mechanism disclosed herein is preferred, but any suitable mechanism may be substituted. The 1/32" increments of height variation are presently useful in drug dispensing, but the height variations may be modified for the particular application. The combination dispenser is not limited to use with blister packs and may be used to fill any suitable container. While the telescoping members which keep the work surface level are presently preferred, any suitable leveling means may be substituted. The cam configuration disclosed is presently preferred, but any shape cam which provides proper height adjustment may be utilized. Further the structure should not be read as to be limited to the axle/pillow block construction disclosed herein. Any suitable indexing mechanism may be utilized to lock the cam in the desired position. The pill or capsule dispensing method is described utilizing manual control of the axle position and the shuttle plate movement. Any or all portions of the method can be mechanized without departing from the applicant's invention. Having described the invention in detail, those skilled in the art will appreciated that modifications may be made of the invention without departing from its spirit. Therefore, it is not intended that the scope of the invention be limited to the specific embodiment illustrated and described. Rather, it is intended that the scope of this invention be determined by the appended claims and their equivalents.

A variable height support structure is provided for use in combination with a solid object dispenser such as a pill or capsule dispenser. The height of the support structure is varied by the use of asymmetrical cam designed to move the support structure surface in discreet units. The apparatus allows a dispenser to fill blister packs with pills or capsules of various shapes and thicknesses without dispenser component reconfiguration or modification or replacement.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel (PDP) and, more particularly, to a composition of plasma display panel. 2. Description of the Background Art In general, a plasma display panel (PDP) device receives much attention as a next-generation display device together with a thin film transistor (TFT), a liquid crystal display (LCD), an EL (Electro-Luminescence) device, an FED (Field Emission Display) and the like. The PDP is a display device which uses a luminescent phenomenon according to an energy difference made when red, green and blue fluorescent materials are changed from an excited state to a ground state after being excited by 147 nm of ultraviolet rays which are generated as a He+X3 gas or N3+X3 gas is discharged from a discharge cell isolated by a barrier rib. Thanks to its properties of facilitation in manufacturing from a simple structure, a high luminance, a high light emitting efficiency, a memory function, a high non-linearity, a 160° or larger optical angular field and the like, the PDP display device is anticipated to occupy a 40″ or wider large-scale display device markets. A structure of the conventional PDP will now be described with reference to FIG. 1 . FIG. 1 is a sectional view showing a structure of a conventional PDP. As shown in FIG. 1 , the conventional PDP includes: a lower insulation layer 20 formed on a lower glass substrate 21 ; an address electrode 22 formed at a predetermined portion on the lower insulation layer 20 ; a lower dielectric layer 19 formed on the address electrode 22 and the lower insulation layer 20 ; an isolation wall 17 defined in a predetermined portion on the lower dielectric layer 19 in order to divide each discharging cell; a black matrix layer 23 formed on the isolation wall 17 ; a fluorescent layer 18 formed with a predetermined thickness on the side of the black matrix layer 23 and the isolation wall 17 and on the lower dielectric layer 19 , and receiving ultraviolet ray and emitting each red, green and blue visible rays; a glass substrate 11 ; a sustain electrode 12 formed at a predetermined portion on the upper glass substrate 11 in a manner of vertically intersecting the address electrode 22 ; a bus electrode 12 formed on a predetermined portion on the sustain electrode 12 ; a first upper dielectric layer 14 formed on the bus electrode 13 , the sustain electrode 12 and the upper glass substrate 11 ; a second upper dielectric layer 15 formed on the first upper dielectric layer 14 ; and a protection layer (MgO) 16 formed on the second upper dielectric layer 15 in order to protect the second upper dielectric layer 15 . The first and second upper dielectric layers 14 and 15 are called upper dielectric layers. The operation of the conventional PDP will now be described. First, as the upper glass substrate 11 and the lower glass substrate 21 of the conventional PDP, an SLS (Soda-Lime Silicate) glass substrate is used. The lower insulation layer 20 is positioned on the lower glass substrate 21 , the SLS glass substrate, and the address electrode 22 is positioned on the lower insulation layer 20 . The lower dielectric layer 19 positioned on the address electrode 22 and the lower insulation layer 20 blocks visible rays emitted toward the lower glass substrate 21 . In order to increase the luminous efficacy, a dielectric layer having a high reflectance is used as the lower dielectric layer 19 . The lower dielectric layer 19 , a translucent dielectric layer with a reflectance of 60% or above, minimizes loss of light. The fluorescent layer 18 is formed by laminating in a sequential order of red, green and blue fluorescent materials. A specific wavelength of visible ray is emitted depending on an intensity of an ultraviolet ray according to plasma generated between the isolation walls 17 . Meanwhile, at a lower surface of the upper glass substrate 11 , the SLS glass substrate, there are formed the sustain electrode 12 positioned to vertically intersect the address electrode 22 and the bus electrode 13 positioned on the sustain electrode 12 . And upper dielectric layers 14 and 15 with an excellent light transmittance are positioned on the bus electrode 13 . The protection layer 16 is positioned on the upper dielectric layer 15 in order to prevent the upper dielectric layer 15 from being damaged due to generation of plasma. Herein, since the first upper dielectric layer 14 is directly contacted with the sustain electrode 12 and the bus electrode 13 , it must have a high softening temperature in order to avoid a chemical reaction with the sustain electrode 12 and the bus electrode 13 . In addition, since the second upper dielectric layer 15 is expected to have a high smoothness because the protection layer 16 is formed thereon, its softening temperature must be lower by scores of ° C. than the first upper dielectric layer 14 . Commonly, the PDP display device has a problem of jitter occurrence. The jitter phenomenon, which occurs as discharging is delayed for a certain time for a specific applied scan pulse, causes a mis-discharging and interferes a high speed driving. The jitter phenomenon is affected mainly by a surface state of the protection layer (MgO) and a crystallinity, an electric permittivity (that is, a dielectric constant) and thickness of each layer, a structure and a gap of isolation walls and electrodes, a driving method, a type and a content of a discharging gas, and the like. Especially, Xe has a low diffusion rate in a discharging space, so if the Xe content is increased in order to obtain a high efficacy characteristics, there is higher probability that the jitter phenomenon occurs. Therefore, in the conventional art, in order to solve the problem of the mis-discharging due to the jitter phenomenon, usually, an electric permittivity of the upper dielectric layer and the lower dielectric layer is increased or their thickness is reduced. In general, the upper dielectric layer and the lower dielectric layer of the PDP has an electric permittivity of about 12˜15 range, and especially, in case of the lower dielectric layer, because it contains TiO 2 powders for increasing the reflectance, it has a higher electric permittivity. However, if the electric permittivity is increased by about twice, a discharge voltage is degraded due to the increase in the capacitance, and thus, about 20% of the overall jitter is reduced. In addition, the jitter characteristics is also changed due to a change in the thickness of the upper dielectric layer and the lower dielectric layer of the PDP. For example, if the gap between the upper electrodes 12 and 13 and the lower electrode 22 narrows as the thickness of the upper dielectric layer and the lower dielectric layer of the PDP is reduced, the discharge voltage would be dropped and thus the jitter can be reduced. The lower dielectric layer and the upper dielectric layer are made of a material having PbO as a principal component with an electric permittivity of about 12˜15, and the gap between the upper electrode and the lower electrode is maintained at about 100 μm. The fabrication method of the lower dielectric layer 19 and the upper dielectric layers 14 and 15 will now be described in detail. The lower dielectric layer is formed as follows: Mixed powders, in which scores of % of oxide in a powder state such as TiO 2 or Al 2 O 3 having a particle diameter of below 2 μm is mixed for improving reflection characteristics and controlling an electric permittivity, is mixed with an organic solvent to produce a paste with a viscosity of about 40000˜50000 cps, and the paste is printed/fired, thereby forming the lower dielectric layer. In this case, the firing temperature is usually at the range of 550˜600° C., and the thickness of the lower dielectric layer is about 20 μm. The upper dielectric layer is formed as follows: a paste obtained by mixing an organic binder is coated to boro-silicate glass (BSG) powder with a size of a particle diameter of 1 μm˜2 μm and containing about 40% of Pb in a screen printing method, and then, the coated paste is fired at a temperature of 550° C.˜580° C. Characteristics change in the jitter according to the change in the electric permittivity will now be described with reference to FIGS. 2A and 2B . FIG. 2A shows jitter occurrence characteristics in case that a distance constant of the upper dielectric layer and the lower dielectric layer for a general PDP is 14, and FIG. 2B illustrates jitter occurrence characteristics in case that a distance constant of the upper dielectric layer and the lower dielectric layer for a general PDP is 25. As shown in FIGS. 2A and 2B , if the electric permittivity is changed from 14 to 25, an operation speed is increased from 1.25 μs to 1.14 μs due to the increase in the capacitance, and according to which the overall jitter is reduced by about 11%. However, since a withstand voltage is reduced according to the increase in the electric permittivity, there is a limitation in increasing the electric permittivity of the PbO-based dielectric material (the material of the upper dielectric layer and the lower dielectric layer). In addition, in the case of increasing the capacitance by reducing the thickness of the material having the same electric permittivity, a problem arises that the conventional dielectric can not withstand the withstand voltage of about 560V. To sum up, as stated above, the dielectric layer of the conventional PDP has the following problem. That is, since the dielectric layer is made of the PbO-based dielectric material, if the electric permittivity of the dielectric is increased in order to reduce the jitter, the withstand voltage would be reduced. Thus, the electric permittivity of the dielectric can not be increased to its maximum. In addition, if the thickness of the upper dielectric layer and the lower dielectric layer is reduced, the withstand voltage would be lowered down, causing the problem that jitter can not be effectively reduced, and thus, a high speed driving is hardly performed. Other conventional PDPs and their fabrication methods are disclosed in the U.S. Pat. No. 5,838,106 issued on Nov. 17, 1998, a U.S. Pat. No. 6,242,859 issued on Jun. 5, 2001, and a U.S. Pat. No. 6,599,851 issued on Jul. 29, 2003. SUMMARY OF THE INVENTION Therefore, one object of the present invention is to provide a composition of a plasma display panel (PDP) capable of effectively reducing a jitter. Another object of the present invention is to provide a composition of a PDP capable of preventing jitter occurrence and mis-discharging by increasing an electric permittivity of a dielectric to its maximum and increasing a capacitance. Still another object of the present invention is to provide a composition of a PDP capable of heightening a luminance and an efficiency by reflecting a portion of a visible ray radiated from a fluorescent material. To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a composition of a PDP containing a ferroelectric transparent ceramics material. To achieve the above object, there is also provided a composition of a PDP, including: a lower dielectric layer containing a ferroelectric transparent ceramics material; an upper dielectric layer containing the ferroelectric transparent ceramics material; and a fluorescent material with the ferroelectric transparent ceramics material mixed therein or having a ferroelectric transparent ceramics thin film. To achieve the above object, there is also provided a ferroelectric transparent ceramics material contained in a composition of a PDP is at least one of (Pb—La)(ZrTi)O 3 , (Pb,Bi)—(ZrTi)O 3 , (Pb,La)—(HfTi)O 3 , (Pb,Ba)—(ZrTi)O 3 , (Sr,Ca)—(LiNbTi)O 3 , LiTaO 3 , SrTiO 3 , La2Ti 2 O 7 , LiNbO 3 , (Pb,La)—(MgNbZtTi)O 3 , (Pb,Ba)—(LaNb)O 3 , (Sr,Ba)—Nb 2 O 3 , K(Ta,Nb)O 3 , (Sr,Ba,La)—(Nb 2 O 6 ), NaTiO 3 , MgTiO 3 , BaTiO 3 , SrZrO 3 or KnbO 3 . The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings: FIG. 1 is a sectional view showing a structure of a PDP in accordance with a conventional art; FIG. 2A shows jitter occurrence characteristics in case that a distance constant of the upper dielectric layer and the lower dielectric layer for a general PDP is 14; FIG. 2B illustrates jitter occurrence characteristics in case that a distance constant of the upper dielectric layer and the lower dielectric layer for a general PDP is 25; and FIG. 3 illustrates ferroelectric transparent ceramics materials applied in the present invention and their characteristics. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. A preferred embodiment of a composition of a PDP that is capable of effectively reducing a jitter by containing a ferroelectric transparent ceramics material thereto will now be described. Namely, preferred embodiments of a composition of a PDP capable of increasing an electric permittivity of a dielectric of a PDP to its maximum by containing the ferroelectric transparent ceramics material, preventing a jitter occurrence and a mis-discharging by increasing a capacitance, and improving a luminance and an efficiency by reflecting a portion of a visible ray radiated from a fluorescent material, will now be described. Herein, increase in the capacitance would lead to reduction of a jitter, which results in preventing of a mis-discharging generated when the PDP is at a low temperature or at a high temperature. In addition, in the present invention, a ferroelectric transparent ceramics material having a high withstand voltage, a high electric permittivity (more than 1000), and a high dielectric strength is applied to the upper and lower dielectrics constituting the PDP device, to thereby increasing a capacitance and enhancing a resistance. Moreover, the ferroelectric transparent ceramics material is also applied to a fluorescent material in order to increase the capacitance, and a visible ray reflection is induced to increase luminance and efficiency of the PDP. Preferably, the PDP comprises a dielectric layer and a phosphor layer including a ferroelectric transparent ceramics material. FIG. 3 illustrates ferroelectric transparent ceramics materials applied in the present invention and their characteristics. The materials as shown in FIG. 3 has a 1000 or higher electric permittivity, a 70% or higher visible ray transmittance, and a 10 6 /m or higher dielectric strength (not shown). Herein, since the electric permittivity, the ferroelectric transparent ceramics material applied in the present invention is higher than 1000, the jitter can be effectively reduced even with the less amount of ferroelectric transparent ceramics material. Among the materials, (Pb, Bi)—(ZrTi)O 3 , (Pb, La)—(MgNbZrTi)O 3 , (Pb,Ba)—(LaNb)O 3 are transparent materials with a transmittance of almost 100% while having the high electric permittivity (higher than 1700), so they can be also applied to the upper dielectric of the PDP device. Various embodiments in which the ferroelectric transparent ceramics material is applied to the PDP to reduce the jitter and thus prevent mis-discharging will now be described. First Embodiment In the first embodiment, at least one of ferroelectric transparent ceramics materials of FIG. 3 is applied to the lower dielectric of the PDP. And the ferroelectric transparent ceramics powder is mixed in the conventional lower dielectric material or a ferroelectric transparent ceramics thin film is additionally formed on the conventional lower dielectric layer to increase a capacitance. First, ferroelectric transparent ceramics powder is prepared and mixed to the lower dielectric material. When the ferroelectric transparent ceramics powder is mixed in the lower dielectric material, the ferroelectric transparent ceramics powder with a particle diameter of a few μm is mixed in a range of 1 weight %˜20 weight % in parent glass powder. The ratio of the lower dielectric composition has been obtained by assuming the weight of the lower dielectric layer is 100 wt %. Thereafter, the mixed powder is formed to a paste with a viscosity of about 40000˜50000, which is then printed and fired to form the lower dielectric layer. When a ferroelectric transparent ceramics thin film is formed on the lower dielectric layer, a lower dielectric layer is formed thinner than the thickness of the conventional lower dielectric layer and the ferroelectric transparent ceramics material is coated with a thickness of thousands of Å at the surface of the thin lower dielectric layer or embedded in the lower dielectric layer by E-beam or sputtering. Namely, by forming the ferroelectric transparent ceramics thin film on the lower dielectric layer, the electric permittivity of the lower dielectric can be improved. In addition, by firing the ferroelectric transparent ceramics powder, the dielectric tissue can become denser, so that a life span of the device can be increased. Second Embodiment In a second embodiment of the present invention, at least one of ferroelectric transparent ceramics materials shown in FIG. 3 is applied to the upper dielectric of the PDP. In addition, the ferroelectric transparent ceramics powder is mixed in the conventional upper dielectric material or a ferroelectric transparent ceramics thin film is additionally formed on the conventional upper dielectric layer in order to increase a capacitance. First, ferroelectric transparent ceramics powder is prepared and mixed to the upper dielectric material. When the ferroelectric transparent ceramics powder is mixed in the lower dielectric material, the ferroelectric transparent ceramics powder with a particle diameter of a few nm is mixed in a range of 1 wt %˜5 wt % in parent glass powder. The ratio of the upper dielectric composition has been obtained by assuming the weight of the upper dielectric layer is 100 wt %. Thereafter, the mixed powder is formed to a paste with a viscosity of about 40000˜50000, which is then printed and fired to form the lower dielectric layer. A ferroelectric transparent ceramics thin film is formed in the same manner as in the conventional art. That is, an upper dielectric layer is formed, on which the ferroelectric transparent ceramics material is coated with a thickness of scores of ˜hundreds of Å. Namely, by forming the ferroelectric transparent ceramics thin film on the upper dielectric layer, the electric permittivity of the upper dielectric can be improved. Preferably, the ferroelectric transparent ceramics material used to heighten the electric permittivity of the upper dielectric is selected from the group consisting of (Pb,Bi)—(ZrTi)O 3 , (Pb,La)—(MgNbZrTi)O 3 , (Pb,Ba)—(LaNb)O 3 which have an extremely high transparent. Third Embodiment In the third embodiment of the present invention, at least one of ferroelectric transparent ceramics material shown in FIG. 3 is applied to a fluorescent material of the PDP. The ferroelectric transparent ceramics material is mixed in power form to a conventional fluorescent material or a ferroelectric transparent ceramics thin film is additionally formed on the conventional fluorescent material, to thereby increasing a capacitance. First, ferroelectric transparent ceramics powder is prepared and mixed to the fluorescent material. When the ferroelectric transparent ceramics powder is mixed to the fluorescent material, the fine ferroelectric transparent ceramics powder with a particle diameter of a few nm is mixed in a range of 1 wt %˜10 wt % in the fluorescent material powder. The ratio of the fluorescent material composition has been obtained by assuming the weight of the fluorescent layer is 100 wt %. When the ferroelectric transparent ceramics thin film is formed on the fluorescent layer, the ferroelectric transparent ceramics thin film is formed with a thickness of below 100 Å at the surface of the conventional fluorescent layer in an E-beam or a Sol-Gel method. That is, with the ferroelectric transparent ceramics thin film thereon, the fluorescent material can discharge a secondary electron and increase a surface charge, so that a mis-discharge occurrence can be reduced. In this respect, if the ferroelectric transparent ceramics thin film is too thick, the ferroelectric transparent ceramics thin film is to absorb ultraviolet rays, reducing the luminance of the PDP. Thus, it is preferred that the ferroelectric transparent ceramics thin film has the thickness of below 100 Å. In the present invention, by applying one of the first to third embodiment to the PDP, the electric permittivity of the PDP device can be increased, and accordingly, the capacitance can be also increased. In addition, because the ferroelectric transparent ceramics material used in the present invention has a high dielectric strength, a discharge withstand voltage can be heightened. Therefore, as the capacitance is increased, the jitter can be reduced, and thus, a mis-discharge occurrence rate can be reduced. Moreover, because the ferroelectric transparent ceramics material can reflect a portion of the visible ray radiated from the fluorescent material, the strength of the discharged visible ray can be increased. As so far described, by mixing the ferroelectric transparent ceramics powder to the upper dielectric or/and lower dielectric material or by forming the ferroelectric transparent ceramics thin film on the upper dielectric or/and lower dielectric, the electric permittivity of the upper and lower dielectric can be heightened. In addition, because the electric permittivity of the upper and lower dielectric is heightened, the capacitance is increased, the jitter is reduced, and the mis-discharge occurrence rate can be considerably reduced. Moreover, by mixing the ferroelectric transparent ceramics powder to the fluorescent material or by forming the ferroelectric transparent ceramics thin film on the fluorescent material, the visible ray radiated from the fluorescent material can be partially reflected, so that the luminance and efficiency of the PDP can be also enhanced. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.

A composition of a plasma display panel (PDP) is disclosed. In order to effectively reduce a jitter, the composition contains a ferroelectric transparent ceramics material.

FIELD OF THE INVENTION [0001] The present invention generally relates to computerized methods and systems for assuring compliance with applicable laws and rules. BACKGROUND OF THE INVENTION [0002] In regulated sectors such as healthcare, finance, and accounting, laws such as the U.S. Health Insurance Portability and Accountability Act (HIPAA), the Gramm-Leach-Bliley Act, the Sarbanes-Oxley Act, and related European laws have been enacted over the past decade to establish new or enhanced standards. The length of these laws, the opacity of the legal language, and the complexity of these acts make it difficult for practitioners to determine whether they are in compliance. This complexity becomes even more significant if computer programmers and information technology professionals wish to build and configure automated systems to help business professionals comply with applicable laws. [0003] There is a need in the art for automated systems for assuring compliance with laws and rules. There is a further need to for an automated compliance checking system that is itself amenable to verifying that its programming is correct an in alignment with the applicable laws and rules. SUMMARY OF THE INVENTION [0004] The present invention makes use of a fragment of stratified Datalog with limited use of negation, and implements a specific format for compositionally representing clauses of a law as Datalog rules. An embodiment of the invention provides a framework to formalize the part of the US Health Insurance Portability and Accountability Act (HIPAA) that regulates information sharing in a healthcare provider environment. This executable formalization of legal regulation was tested by implementing a prototype web-based message system and compliance checker based on the Vanderbilt Medical Center MyHealth web portal. [0005] The formalization of the present invention was also used to examine conflicts in the HIPAA regulation. By querying the logic program to return all the possible agents who could gain access to patient information, some anomalies were found regarding lack of regulation of government employees who are granted access to medical data, for example. While the present disclosure focuses on the formalization of HIPAA, the teachings of the present invention can generally be applied to a broad class of privacy regulations. For example, it may be applied to those consistent with Nissenbaum's theory of Contextual Integrity. [0006] Those of skill in the art will appreciate that the teaching of the present invention can be applied to laws, rules, or regulations with similar structures to those of HIPAA as used as an example in the present disclosure. Indeed, the teachings of the present invention can be applied to other aspects of HIPAA not discussed here. [0007] The present invention may also be enhanced by generating meaningful annotated audit logs, as by logging messages with semantic information about each action and compliance issues associated with it. In addition to automating compliance tasks, a formal presentation of HIPAA (or other regulations) could also be useful in training medical personnel about the consequences and non-consequences of the law. These and other extensions of the present invention will be obvious to those of ordinary skill in the art without deviating from the teachings described above and claimed below. BRIEF DESCRIPTION OF THE DRAWINGS [0008] FIG. 1 is a block diagram of a computer system on which embodiments of the present invention can be implemented. [0009] FIG. 2 is a block diagram of a distributed computing system on which embodiments of the present invention can be implemented. [0010] FIG. 3 is a flow diagram of a method according to an embodiment of the present invention. [0011] FIG. 4 is a representation of a graphical user interface according to an embodiment of the present invention. [0012] FIG. 5 is a representation of a graphical user interface according to an embodiment of the present invention. [0013] FIG. 6 is a representation of a graphical user interface according to an embodiment of the present invention. DETAILED DESCRIPTION [0014] Among other things, the present invention relates to methods, techniques, and algorithms that are intended to be implemented in a digital computer system. By way of overview that is not intended to be limiting, digital computer system 100 as shown in FIG. 1 will be described. Such a digital computer or embedded device is well-known in the art and may include variations of the below-described system. [0015] FIG. 1 is a block diagram of a system 100 configured to implement one or more aspects of the present invention. System 100 may be a computer workstation, personal computer, or any other device suitable for practicing one or more embodiments of the present invention. As shown, system 100 includes one or more processing units, such as central processing unit (CPU) 102 , and a system memory 104 communicating via a bus path that may include a memory bridge 105 . CPU 102 includes one or more processing cores, and, in operation; CPU 102 is the master processor of system 100 , controlling and coordinating operations of other system components. System memory 104 stores software applications and data for use by CPU 102 . CPU 102 runs software applications and optionally an operating system. Memory bridge 105 , which may be, e.g., a Northbridge chip, is connected via a bus or other communication path (e.g., a HyperTransport link) to an I/O (input/output) bridge 107 . I/O bridge 107 , which may be, e.g., a Southbridge chip, receives user input from one or more user input devices such as keyboard 108 or mouse 109 and forwards the input to CPU 102 via memory bridge 105 . In alternative embodiments, I/O bridge 107 may also be connected to other input devices such as a joystick, digitizer tablets, touch pads, touch screens, still or video cameras, motion sensors, and/or microphones (not shown). [0016] One or more display processors, such as display processor 112 , are coupled to memory bridge 105 via a bus or other communication path 113 (e.g., a PCI Express, Accelerated Graphics Port, or HyperTransport link); in one embodiment display processor 112 is a graphics subsystem that includes at least one graphics processing unit (GPU) and graphics memory. Graphics memory includes a display memory (e.g., a frame buffer) used for storing pixel data for each pixel of an output image. Graphics memory can be integrated in the same device as the GPU, connected as a separate device with the GPU, and/or implemented within system memory 104 . Display processor 112 periodically delivers pixels to a display device 110 that may be any conventional CRT or LED monitor. Display processor 112 can provide display device 110 with an analog or digital signal. [0017] A system disk 114 is also connected to I/O bridge 107 and may be configured to store content and applications and data for use by CPU 102 and display processor [0018] 112 . System disk 114 provides non-volatile storage for applications and data and may include fixed or removable hard disk drives, flash memory devices, and CD-ROM, DVD ROM, Blu-ray, HD-DVD, or other magnetic, optical, or solid state storage devices. [0019] A switch 116 provides connections between I/O bridge 107 and other components such as a network adapter 118 and various add-in cards 120 and 121 . Network adapter 118 allows system 100 to communicate with other systems via an electronic communications network, and may include wired or wireless communication over local area networks and wide area networks such as the Internet. [0020] Other components (not shown), including USB or other port connections, film recording devices, and the like, may also be connected to I/O bridge 107 . For example, an audio processor may be used to generate analog or digital audio output from instructions and/or data provided by CPU 102 , system memory 104 , or system disk 114 . Communication paths interconnecting the various components in FIG. 1 may be implemented using any suitable protocols, such as PCI (Peripheral Component Interconnect), PCI Express (PCI-E), AGP (Accelerated Graphics Port), HyperTransport, or any other bus or point-to-point communication protocol(s), and connections between different devices may use different protocols, as is known in the art. [0021] In one embodiment, display processor 112 incorporates circuitry optimized for graphics and video processing, including, for example, video output circuitry, and constitutes a graphics processing unit (GPU). In another embodiment, display processor 112 incorporates circuitry optimized for general purpose processing. In yet another embodiment, display processor 112 may be integrated with one or more other system elements, such as the memory bridge 105 , CPU 102 , and I/O bridge 107 to form a system on chip (SoC). In still further embodiments, display processor 112 is omitted and software executed by CPU 102 performs the functions of display processor 112 . [0022] Pixel data can be provided to display processor 112 directly from CPU 102 . In some embodiments of the present invention, instructions and/or data representing a scene are provided to a render farm or a set of server computers, each similar to system 100 , via network adapter 118 or system disk 114 . The render farm generates one or more rendered images of the scene using the provided instructions and/or data. These rendered images may be stored on computer-readable media in a digital format and optionally returned to system 100 for display. [0023] Alternatively, CPU 102 provides display processor 112 with data and/or instructions defining the desired output images, from which display processor 112 generates the pixel data of one or more output images, including characterizing and/or adjusting the offset between stereo image pairs. The data and/or instructions defining the desired output images can be stored in system memory 104 or a graphics memory within display processor 112 . In an embodiment, display processor 112 includes 3D rendering capabilities for generating pixel data for output images from instructions and data defining the geometry, lighting shading, texturing, motion, and/or camera parameters for a scene. Display processor 112 can further include one or more programmable execution units capable of executing shader programs, tone mapping programs, and the like. [0024] In one embodiment, application 150 is stored in system memory 104 . Application 150 may be any application configured to display a graphical user interface (GUI) on display device 110 . Application 150 may be configured to generate and modify documents based on input received from a user. For example, application 150 may be a word processing application or an image editing program. [0025] It will be appreciated that the system shown herein is illustrative and that variations and modifications are possible. The connection topology, including the number and arrangement of bridges, may be modified as desired. For instance, in some embodiments, system memory 104 may be connected to CPU 102 directly rather than through a bridge, and other devices may communicate with system memory 104 via memory bridge 105 and CPU 102 . In other alternative topologies display processor 112 may be connected to I/O bridge 107 or directly to CPU 102 , rather than to memory bridge 105 . In still other embodiments, I/O bridge 107 and memory bridge 105 may be integrated in a single chip. In addition, the particular components shown herein are optional. For instance, any number of add-in cards or peripheral devices might be supported. In some embodiments, switch 116 is eliminated, and network adapter 118 and add-in cards 120 , 121 connect directly to I/O bridge 107 . [0026] An embodiment of the present invention provides a method for representing and processing laws, rules, regulations, and policies in a messaging system. Among other things, the present invention provides a method for representing and processing privacy laws and compliance to such laws is provided. [0027] The U.S. Health Insurance Portability and Accountability Act (HIPAA) title II was enacted in 1996. In an embodiment of the present invention, HIPAA regulations in a messaging system are described. As shown in FIG. 2 , health providers desire to pass messages among doctors 202 , nurses 204 , and patients 206 , for example, through a centralized message server 200 . To address certain privacy concerns, however, such messages must be closely controlled so as to assure compliance with such laws as HIPAA. Towards meeting this need, the present invention provides a novel approach for implementing a privacy policy on server 100 so as to reasonably assure compliance. [0028] The HIPAA regulation is complex for non-experts to follow for a number of reasons. For example, the law generally allows protected information to be shared between appropriate entities for the purpose of treatment. But clause 164.508.a.2, for example, apparently contradicts this by stating that if the protected information is a psychotherapy note then a covered entity, e.g., a health plan, a health care provider or a clearinghouse, must obtain an authorization before disclosure. Thus, simple reasoning based on actions allowed by one portion of the law, without accounting for prohibitions in other portions of the law, may give erroneous results. [0029] The present invention provides a formalization of applicable parts of the HIPAA regulation in a form that can be used in a messaging system. Through Web access to a centralized system, such a messaging system allows patients and medical professionals to exchange messages and, as necessary, request and view information such as prescriptions or lab test results. [0030] The present invention can also be used in such systems to respond to requests from other hospitals and clinics, law enforcement, insurers, and other organizations. A compliance module that decides, as messages are composed or entered into the system, whether a message complies with HIPAA is disclosed. The present invention can further be extended and modified as HIPAA and other applicable laws are modified or supplemented. [0031] Starting with a view of privacy policy, business processes, and compliance, an embodiment of the present invention implements a stratified fragment of the logic programming language Prolog with limited use of negation. [0032] In addition to representing HIPAA precisely enough to determine whether any particular action within the scope of the messaging system would comply with the applicable law, the present invention provides a formalization that is verifiable by lawyers, medical, and computer professionals alike. For this reason, the present invention formalizes the law so that the Prolog presentation can be read and understood section by section, with the meaning of the entire presentation determined in a systematic way from the meaning of its parts. In addition to supporting outside review and audit, this approach also allows HIPAA formalization to be combined with additional policies adopted by regulated enterprises. [0033] An embodiment of the present invention focuses on a specific privacy law, identification of a specific fragment of stratified Datalog that appears appropriate to the task, and a reliance on a general theory of privacy previously articulated for a more expressive but less commonly implemented logical framework. [0034] The present invention identifies a specific fragment of stratified Datalog with one alternation of negation which suits the present invention and supports a certain degree of policy compositionality. The present invention uses this framework to formalize the part of the HIPAA law that regulates information sharing in a healthcare provider environment. The structure of logic programming with predicates, query, and facts correspond to the legal clauses, actions being performed, and relations like roles defined in the law. As a subset of logic programming, the methods of the present invention facilitate the addition of cross references as present in the law. [0035] The present invention also implements a prototype compliance checker and message system as a web-based system. This embodiment is used to decide if a message that a practitioner is about to send is in compliance with the HIPAA regulation. The present invention is also used to examine conflicts in the HIPAA regulation. [0036] While the present invention focuses on the formalization of HIPAA, those of skill in the art will appreciate that the teachings as presented herein apply generally to a broad class of privacy regulations. More generally, the present invention can be applied to other laws, rules, and regulations with an appropriate structure that are used to control actions. [0037] In the present disclosure, the key features and structure of the HIPAA policy and an information sharing model of the present invention will be introduced and summarized. Next, the modified computer language as used in the present invention to model the HIPAA policy and the rule composition approach will be described. [0038] HIPAA both explicitly permits certain transfers of personal health information and prohibits some disclosures. For example, HIPAA provides federal protections for personal health information held by covered entities and gives patients an array of rights with respect to that information. Also, HIPAA regulates the use and disclosure of personal health information. [0039] In HIPAA terminology, a covered entity is a health plan, a health care clearinghouse, or a health care provider that transmits health information in electronic form. Protected health information is individually identifiable health information that is transmitted or maintained in electronic or other media. [0040] For purposes of describing features and aspects of the present invention, the present disclosure focuses section 164 of HIPAA, which regulates the security and privacy issues in the health care industry. One of skill in the art, however, will appreciate that the teachings provided herein are not so limited and can actually be extended to many other applications with appropriately structured laws, rules, or regulations, for example. [0041] An embodiment of the present invention covers general provisions, security standards for the protection of electronic health information, and privacy of individually identifiable health information. The present disclosure specifically addresses subpart 164.502, which covers the general rules for uses and disclosures of protected health information. Of the many subparts it references, the present disclosure considers subpart 164.506, which covers uses and disclosures to carry out treatment, payment, or health care operations, and subpart 164.508, which covers uses and disclosures requiring an authorization. [0042] Shown in FIG. 3 is method for checking compliance with a law such as HIPAA laws according to an embodiment of the invention. Although the method is described in conjunction with the various system representations set forth herein, persons skilled in the art will understand that any system that describes the method steps, in any order, falls within the scope of the present invention. [0043] As shown at step 302 , a desired action is determined. In an embodiment of the invention described further below, the desired action is sending a message that is subject to laws or rules, but other actions can also be processed according to the teachings of the present invention. For example, any action for which there exist certain structured rules is appropriate for implementation according to the teachings of the present invention. [0044] At step 304 , necessary information is then gathered so that determinations can be made as to whether the desired action is to be allowed or forbidden. In an embodiment for a messaging system as described further below, the information collected at step 304 includes To (e.g., to whom a message is addressed), From (e.g., from whom a message is sent), About (e.g., about what is the message), Type (e.g., type of message), Purpose (e.g., purpose of the message), In Reply To (e.g., information about whether the present message is in reply to another message), Consented By (e.g., the person who consented to the message), and Belief (e.g., information about whether the sender has a belief about the subject message). [0045] Shown in FIG. 4 are certain aspects of a graphical user interface (GUI) as may be implemented in accordance with the teachings of the present invention. As shown, screen 402 provides an interface by which the contents of a desired message may be entered. This screen seeks to provide a straightforward for inputting the broad range of patient messages. Shown in FIG. 4 is to field 404 , From field 406 , About field 408 , Type field 410 , and Purpose field 412 . Also show in FIG. 4 is drop down menu 420 for Purpose field 412 . Drop down menus can also be implemented for the other fields of the present invention. Other input techniques are likewise possible in other embodiments of the present invention. Further shown in FIG. 5 are Belief field 414 , and Message field 416 . It should be noted that fields 414 and 416 as well as other fields can also be included in screen 402 of FIG. 4 . [0046] According to an embodiment of the invention to be described further below, the To and From fields indicate the recipient and sender of the message. The About field identifies whose personal health information is contained in the message. The Type field defines, for example, the type of healthcare information mentioned in the message. Further examples include blood tests, X-ray results, or psychotherapy notes. [0047] The Purpose field indicates a reason the message is being sent, such as for medical treatment. When the purpose is needed to determine compliance, the present invention assumes that a professional has asserted a purpose, or an asserted purpose is in some way inferred and made available as input to the compliance module. In an embodiment, the present invention infers when a purpose is needed, and provides the sender with a pulldown menu indicating purposes that would allow the message to be sent. [0048] The In Reply To field describes a disclosure where the message is sent as a response to some earlier message. The Consented By field indicates which people have consented to the message disclosure. [0049] The Belief field contains a collection of assertions about the current situation, such as whether this is a medical emergency, or whether disclosure is (in the opinion of the sender) in the best interest of the health of the patient. Some beliefs may not be indisputable facts in the sense that another person may think differently. But a sender may assert a belief (e.g., from a pulldown menu) or the sender's belief may be established by some other means. In an embodiment, once a message is allowed based on a belief, this reason is recorded and made available to a subsequent audit. [0050] Turning back to the method of FIG. 3 , at step 306 , a determination is made as to whether the desired action is permitted by certain of the applicable laws or rules. In an embodiment of the invention, a messaging system described further below determines whether a desired action is permitted by all the applicable laws or rules (e.g., HIPAA laws). It should be noted, however, that other laws or rules may have a structure where different approaches may be taken. For example, other embodiments may only require that a certain subset of laws or rules allow a particular action. [0051] At step 308 , a determination is made as to whether the desired action is forbidden by certain of the applicable laws or rules. In an embodiment of the invention, a messaging system described further below determines whether a desired action is forbidden by at least one of the applicable laws or rules (e.g., HIPAA laws). It should be noted, however, that other laws or rules may have a structure where different approaches may be taken. For example, other embodiments may allow a particular action a condition exists where one law or rule allows an action but another law or rule forbids the action. Other manners of addressing conflicts in laws and rules are discussed further below. [0052] At step 310 , a determination is made as to whether an exception applies to the desired action as set forth in the applicable laws or rules. In an embodiment of the invention, a messaging system described further below determines whether an exception applies to a desired action that, for example, takes precedence over the results of steps is forbidden by at least one of the applicable laws or rules (e.g., HIPAA laws). It should be noted, however, that other laws or rules may have a structure where different approaches may be taken. For example, other embodiments may allow a particular action a condition exists where one law or rule allows an action but another law or rule forbids the action. Other manners of addressing conflicts in laws and rules are discussed further below. [0053] In an embodiment, patients or professionals enter a message into a centralized message system as shown in screen 402 of FIG. 4 . In this embodiment, the centralized message system can deliver the message by making it visible to other users. Messages may be simple questions from a patient, or may contain lab test results or other forms of protected medical information. Given information about the message, and other information such as the roles of the sender and receiver in the hospital, the HIPAA compliance module of the present invention decides whether delivery of the message complies with HIPAA. Thus, upon entering the appropriate information at screen 402 , a user may be presented with screen 502 that, after execution certain methods of the present invention, notifies the user that the message was in compliance with HIPAA regulations and was sent. Screen 602 , however, is presented if, after execution of certain methods of the present invention, a message is either forbidden or not permitted by HIPAA regulations and the message is not sent. [0054] A structure of the present invention that provides for the formalization of laws, rules, regulations, and policies such as contained in HIPAA will now be described. Among other things, this embodiment of the present invention is designed to make compliance decisions based on eight message characteristics: To, From, About, Type, Purpose, In Reply To, Consented By and Belief. One of ordinary skill in the art will, however, understand how the discussion below can be modified without deviating from the teachings of the present invention. [0055] Action: For the purpose of determining compliance, a message action is represented as an eight-tuple a= u src ,u dst ,u abt , m typ , m pur , a reply , c, b , where (note that underlining indicates a set) [0000] u src , u dst , u abt ε U (the set of users or agents), m typ ε T (the set of types of messages), m pur ε P (the set of purposes), a reply ε A (the set of actions), C = < u by , c type > ε C (the tuple of consents) with u by ε U (the set of users) and c typ ε CT (the set of consent types), b = < u by , U abt , b f > ε B (the set of beliefs) with u by , u abt ε U (the set of users) and b f ε BF (the set of beliefs). [0056] In this embodiment, a HIPAA policy is a function from actions to Booleans (true or false), indicating permission or prohibition. [0000] U×U×U×T×P×A×C×B→{T,F} [0057] Category: A category is a set of field values defining the conditions when a legal clause is applicable to a particular action. For example, one common category of actions is those with type indicating protected health information and purpose indicating medical treatment. [0058] Subcategories: Some field values may indicate that the action belongs to a subcategory of another category of actions. For example “psychotherapy note” is a subtype of “health records,” which implies that policy about health records could also affect decisions about psychotherapy note, but not vice versa. More generally, the possible values associated with any field may be partially ordered. [0059] Roles: While it is possible to express policy about specific individuals, HIPAA policies are written using roles. For example, an individual could be a nurse or a doctor. When an action is considered, the system of the present invention receives the names of the sender and recipient, for example, and then uses information about the hospital to determine the respective role(s). For patients, similar processing (formalized in Prolog) is used to determine whether the patient is an adult or a minor. [0060] Further concepts for the formalization of HIPAA are introduced using 164.508.a.2 of HIPAA as a running example. As stated above, 164.508 as a whole governs uses and disclosures of protected health information that require an authorization. Specifically, 164.508.a.2 states, among other things, that a covered entity must obtain an authorization for any use or disclosure of psychotherapy note, except if it is to be used by the originator of the psychotherapy note for treatment. [0061] Requirement: An action that falls into the category of a legal clause is allowed only if the requirement in the clause is satisfied. For example, 164.508.a.2 states that the specified action is allowed only if an authorization is obtained. [0062] Exception: An exception in a legal clause qualifies its category. For example, 164.508.a.2 states that if the purpose of the action is for use by the originator of the psychotherapy note for treatment, then the requirement does not apply. [0063] Clause vs. Rule: For ease of exposition, a labeled paragraph in the HIPAA law is called a clause, and its translation into logic rules. [0064] To illustrate this terminology, a clause with category given by predicate a, requirement predicate c and exceptions e can be expressed as the following rules: [0000] permitted_by R ( a e ) c [0000] forbiddent)by R ( a e ) c [0000] R_not_applicable a e [0065] Combination: A central concept in the approach of the present invention is the manner in which a policy composed of several legal clauses is expressed by a combination of the associated permitted_by and forbidden_by rules. Given rules R1 . . . Rm, any action is consistent with the policy of these rules if it is permitted by at least one of the rules and not forbidden by any of them. [0000] compliant_with R1 . . . Rm (permitted_by R1 . . . permitted_by Rm ) (forbiddent_by R1 . . . forbiddent_by Rm ) [0066] This approach allows each clause to be translated into rules that are then combined in a systematic way to express the requirements of the law. [0067] Cross-Reference: Frequently a requirement of a clause involves a reference to other clauses of the law. In the formal definition discussed below, the present invention requires an acyclicity condition so that the cross-reference relation among HIPAA clauses forms a directed acyclic graph. [0068] A fragment of stratified Datalog is identified with one alternation of negation, which is referred to for simplicity as pLogic, which suits the present formalization approach and supports a certain degree of policy compositionality. It is designed so that, given an action, the present invention can verify whether the action is compliant with the written policy. [0069] The method of the present invention for translating HIPAA into stratified Datalog with one alternation of negation is structured according to the form of pLogic rules and pLogic policies given below. As is standard in logic programming, a predicate is a symbol with an associated arity. Because the present invention uses only Datalog, a term is a variable (starting with an upper-case letter) or an object constant (starting with a lower-case letter). An atom is an n-ary predicate applied to n terms. A literal is an atom. An expression is ground if it contains no variables. [0070] Intuitively, a pLogic rule is a translation of a HIPAA clause into permitted and forbidden conditions. Each rule R therefore gives conditions on predicates permitted_by R or forbidden_by R , taking actions as arguments, indicating whether the action should be allowed or denied. pLogic facts may be used to define subsidiary predicates or other inputs to the compliance process. [0071] pLogic Facts: A pLogic fact is an atom gi(a1, . . . , an) written using any relation gi of arity n. [0000] pLogic Rule: The pLogic rules associated with a HIPAA clause Ri possibly cross-referencing clauses Rj, . . . , Rk have the form: [0000] permitted_by Ri ( A ) category — Ri ( A ) exception — Ri ( A ) requirement — Ri ( A ) (permitted_by Rj ( A ) op i,j+1 . . . op i,k permitted_by Rk ( A )) [0000] forbidden_by Ri ( A ) category — Ri ( A ) exception — Ri ( A ) (requirement — Ri ( A ) forbiddent_by Rj ( A ) . . . forbidden_by Rk ( A )) [0072] where permitted_by Ri , forbidden_by Ri , category_R i , exception_R i and requirement_R i are predicates on actions, each op i,x is either the (AND) or the (OR) operator, as specified in the corresponding legal clause in HIPAA, category_Ri, exception_Ri and requirement_Ri may appear as the head of additional Datalog rules considered to be part of the rule expressing the clause, Every variable in the body must appear in the head, As indicated, permitted_by Ri may depend on permitted_by Rj for another clause R j , but not forbidden_by Rj , and similarly forbidden_by Ri may depend on another forbidden_by Rj but not permitted_by Rj . [0078] In the definition given above, the requirements are considered to be both may and must. However, the definition could easily be generalized to put one requirement in the permit rule and another in the forbid rule. [0079] pLogic Policy: An pLogic policy is a set Δ of pLogic rules and pLogic facts whose dependency graph (defined below) is acyclic. [0080] The dependency graph V, E of Δ is defined as follows. The vertices V are predicates occurring in Δ and E contains a directed edge from u to v exactly when there is a rule in Δ where the predicate in the head is u and the predicate v appears in the body. The acyclicity condition ensures a nonrecursive stratified Datalog program. [0081] Entailment for pLogic is based on the usual stratified semantics from deductive databases and logic programming. pLogic policy is decidable pLogic policy is a nonrecursive logic program with negation and without function constants. Restricting the arity of the predicates to a constant reduces the complexity to polynomial time. [0082] pLogic is designed so that prohibition takes precedence over permission. But care must be taken in translating HIPAA into pLogic when it comes to overlapping clauses. Two rules are said overlap if the category and exceptions of the two rules allow them to apply to the same action, and one is a subcase of the other if its category and exception make it apply to every action satisfying the category and exceptions of the other. Two overlapping rules conflict if one permits an action while another forbids it; two rules are disjoint if there exists no action to which both apply. [0083] Some example relationships between rules are illustrated in Table 1. All three rules presented in the table are pairwise overlapping. But only rule R 502a1ii has a category that is a subcategory of another, specifically rule 502a1v. [0000] Category Requirement A from A type A purpose A consent R 502a1ii + covered entity health records treatment * permitted_byR506(A) − covered entity health records treatment * forbidden_byR506(A) R 502a1v + covered entity health records * * permitted_byR506(A) − covered entity health records * * forbidden_byR506(A) R 508 + * psy-therapy note * <x, authz> − * psy-therapy note * <x, authz> Table 1 Examples of Overlapping Rules in HIPAA [0084] Based on experience with HIPAA, when two rules are disjoint or overlapping, but neither is a subcase of the other, the general approach of the present invention provides the correct results: an action is permitted if it is permitted by at least one rule and not forbidden by any. When one clause addresses a subcase of another, it often appears to be the expressed intent of the law to have the more specific clause take precedence over the other clause. In other words, it appears correct to disregard both the permitted and forbidden conditions of the less specific clause, and use only the more specific clause. The present invention can handle this correctly within pLogic, by using exceptions to narrow the scope of the less specific rule so that it is not applied in the conflicting subcase. [0085] Generally, disregarding the added complexity of cross-references and exceptions, conflicts happen when the category of an action matches two or more rules, the requirement for one rule is satisfied and the requirement for the other is violated. In the above example, an action like [0086] from: covered entity, type: health records, for: treatment, requirement: —as satisfying R 506 [0000] is permitted by R 502a1ii but forbidden by R 502a1v . Because this embodiment of the invention is designed to give precedence to parts of the law that forbid an action, an action that is permitted by one of two overlapping rules and forbidden by the other will be considered forbidden. Of course, other prioritizations of laws and rules may generate different results. [0087] In cases where one rule specifies a category that is a proper subset of the category of another rule, giving precedence to denial may be incorrect because the more specific clause of the law was intended to have higher priority. A way to modify the translation of the law into rules is to add exceptions to the more generic rule to make the two rules disjoint. In the example illustrated above (in the table), an exception to rule R 502a1ii is added specifying for: treatment. This causes rule R 502a1ii not to be applied when the purpose is treatment, eliminating the problematic conflict. Another solution is to assign priorities and split all the overlapping rules to make them disjoint. If applied throughout, the alternative approach could produce a more efficient compliance checker, but requires substantial effort to properly split all rules because many HIPAA rules are overlapping. [0088] Additionally, the approach of the present invention has the advantage that it better preserves the correspondence between the logic rules and the corresponding legal clauses. To elucidate the structure of HIPAA and its translation in logic an example is provided in the appendix. [0089] Other embodiments of the present invention involve audit, implicit information, and obligations. As mentioned above in connection with beliefs asserted by the sender of a message, compliance decisions depend on the accuracy of the information provided by the users. Users of a hospital medical system are generally professional practitioners who will provide correct information. But there may be some instances in which faulty or questionable information is entered. To provide accountability, auditing systems can be added to provide trace logs of how decisions are made and when beliefs or other potentially questionable input is used. [0090] Another embodiment of the present invention can infer relevant information to reduce the amount of information the user has to provide to send a message. This can be achieved by extracting information from the message itself or by reasoning about the context of an action and information in previous messages among other things. [0091] Since obligations to perform future actions arise in many privacy contexts, the approach of the present invention can be applied to support broader obligations. While the present invention represents the past explicitly through the in-reply-to field of messages, which produces linked structures of relevant past actions, future obligations may require an additional approach. But Although Prolog and Datalog do not have a concept of past or future, one method of providing a chronology can be to periodically run a scheduled process which scans the log and checks whether, for any particular action, any further action is required. The concerned person can then be notified. [0092] An example for encoding a law such as HIPAA will now be provided. The teachings of the present example, can be extended to other HIPAA laws. Indeed, the present teachings can be extended to many other applications. [0093] In this example, a part of clause R164.502 is considered which states that a covered entity can give out health records if it adheres to R 502b or R 506a2 and satisfies additional conditions: [0094] 164.502.b Standard: Minimum necessary 164.502.b.1 Minimum necessary applies. When using or disclosing protected health information or when requesting protected health information from another covered entity, a covered entity must make reasonable efforts to limit protected health information to the minimum necessary to accomplish the intended purpose of the use, disclosure or request. 164.502.b.2 Minimum necessary does not apply. This requirement does not apply to: (i) Disclosure to or requests by a health care provider for treatment; [0100] In short, R 502b implies that when the covered entity is giving out the information to another covered entity, it should ensure that it is minimal information except for the purposes of treatment. Thus, the category for this clause is from: covered entity and to: covered entity and type: health records. The requirement is belief: minimal. The exception is for: treatment. [0101] 164.502 Uses and disclosures of protected health information. 164.502.a Standard. A covered entity may not use or disclose protected health information, except as permitted or required by this subpart or by subpart C of part 160 of this subchapter. 164.502.a.1 Permitted uses and disclosures. A covered entity is permitted to use or disclose protected health information as follows: (ii) For treatment, payment, or health care operations, as permitted by and in compliance with 164.506; [0105] The clause R 502aii implies that when a covered entity is sending health records for the purposes of treatment then it should also comply with R 506 . Here the category is from: covered entity and type: health records and purpose: treatment. The requirement is to comply with R 506 . [0106] Thus the logic translation of the two clauses is: [0107] Rules:— [0000] permitted_by 502b (A)   (A from = covered entity)   (A type =health records)   (A to =covered entity)   (A purpose =treatment)   (A belief =minimal) forbidden_by R502b (A)   (A from =covered entity)   (A type =health records)   (A to =covered entity)   (A purpose =treatment)   (A belief =minimal) permitted_by R502aii (A)   (A from =covered entity)   (A type =health records)   (A purpose =treatment)   forbidden_by R506 (A) [0108] Policy:— [0000]   compliant_with HIPAA    permitted_by 502b    permitted_by R502aii    (forbidden_by R502b    forbidden_by R502aii ) [0109] Attributes:— [0110] Attributes and relations are defined. Consider a relation called in Role that identifies a particular individual and their role. Consider the example where dr_cox, a doctor, and carla, a nurse, work at a hospital, Sacred Heart. [0000] inRole(Carla, nurse) inRole(dr_cox, doctor) inRole(doctor, covered entity) inRole(nurse, covered entity) inRole(sacredHeart, covered entity) employeeOf(sacredHeart, dr_cox) employeeOf(sacredHeart, dr_cox) [0111] A transitive closure of these rules is also possible which would imply that carla and dr_cox are a covered entity. [0112] Given this policy and the list of attributes, assuming dr_cox and carla work for the same hospital and R 506 is satisfied, an action that would be allowed with this particular rule system is: [0113] (from: carla, to: dr_cox, type: health records, for: treatment) [0114] The policy would permit this action because of the rule R 502aii An action like [0115] (from: carla, to: xyz, type: health records, for: treatment) [0000] would not be allowed as there is no relation stating that xyz is some kind of covered entity and there is no other rule in the policy permitting this action. [0116] It should be appreciated by those skilled in the art that the specific embodiments disclosed above may be readily utilized as a basis for modifying or designing other techniques for carrying out the same purposes of the present invention. It should also be appreciated by those skilled in the art that such modifications do not depart from the scope of the invention as set forth in the appended claims.

The complexity of regulations in healthcare, financial services, and other industries makes it difficult for enterprises to design and deploy effective compliance systems. The present invention supports compliance by using formalized portions of applicable laws to regulate business processes that use information systems. An embodiment of the present invention uses a stratified fragment of Prolog with limited use of negation to formalize a portion of the US Health Insurance Portability and Accountability Act (HIPAA). An embodiment of the invention provides for deployment in a prototypical hospital that implements a Web portal messaging system.

FIELD OF THE INVENTION The present invention relates generally to high-performance amplifiers for communications applications, and specifically to highly-linear broadband amplifiers. BACKGROUND OF THE INVENTION Modern mobile communications systems use multiple channels, closely spaced over an assigned frequency band. In order to avoid intermodulation products and spectral regrowth, both in and out of band, it is essential that RF power amplifier circuits used in these systems be highly linear. A high level of linearity is also required in single-channel transmitters which transmit a wideband, variable-envelope signal, such as a CDMA signal. A major source of nonlinearity is distortion, which occurs due to nonlinear amplitude and phase response of the amplifier, particularly as power nears the saturation level. Third-order distortion nonlinearities typically give the strongest intermodulation products, but fifth- and even seventh-order products can be significant. Since a typical cellular communications band has a spectral width of around 25 MHz, high-order intermodulation products in a wideband base station amplifier with large channel spacing can create distortion over a band that is more than 150 MHz wide. One method of correcting for amplifier distortion, and thus improving linearity, is predistortion, in which a controlled, nonlinear distortion is applied to the amplifier input signals. Predistortion circuitry is designed to give nonlinear amplitude and phase characteristics complementary to the distortion generated by the amplifier itself, so that ideally, the distortion is canceled in the amplifier output over the entire signal bandwidth. A feedback connection is generally provided from the amplifier output to the predistortion circuitry, for use in adjusting predistortion coefficients for optimal linearization. Predistortion is often applied to baseband signals, as described, for example, in U.S. Pat. No. 4,291,277, which is incorporated herein by reference. The predistorted signals are then upconverted and fed to the power amplifier. Predistortion may also be combined with other methods of linearization, such as feedforward error correction, as described in U.S. Pat. No. 5,760,646, which is likewise incorporated herein by reference. Various schemes have been proposed for digital-domain predistortion of the baseband signals. Because of the very high bandwidth of the intermodulation products, as mentioned above, extremely fast, wideband processing circuitry has been required in order to compensate effectively for distortion without causing new problems such as aliasing. The required sampling rate is particularly high when the power amplifier has a significant level of high order (fifth or seventh order) intermodulation response. For example, U.S. Pat. No. 4,700,151, which is incorporated herein by reference, describes a predistortion system that operates on baseband signals. The signals are sampled and then interpolated to generate samples having a higher sample rate, thus providing an extended bandwidth as required for effective predistortion. U.S. Pat. No. 5,650,758, also incorporated herein by reference, describes a pipeline architecture for a wideband digital predistortion circuit. Other predistortion schemes are described in an article by Cavers, entitled “Amplifier Linearization Using a Digital Predistorted with Fast Adaptation and Low Memory Requirements,” published in IEEE Transactions on Vehicular Technology, vol. 39, no. 4 (November 1990), pages 374-382, which is incorporated herein by reference. SUMMARY OF THE INVENTION It is an object of some aspects of the present invention to provide an improved predistortion circuit for use in amplification of radio frequency signals. It is a further object of some aspects of the present invention to provide a digital predistortion circuit that operates at a reduced sample rate relative to predistortion circuits known in the art. In preferred embodiments of the present invention, an input signal having a given initial bandwidth is processed by a digital predistortion circuit and is then converted to analog form, upconverted and amplified by a radio frequency (RF) power amplifier. The predistortion circuit receives a stream of samples of the input signal and interpolates the samples to effectively increase the sample bandwidth to an expanded bandwidth at least twice the given bandwidth of the signal. A nonlinear correction is applied to predistort the interpolated samples. The predistorted samples are then low-pass filtered and decimated, so that the bandwidth of the sample stream output by the digital predistortion circuit is again reduced to be on the order of the initial bandwidth. As a result of this design, digital/analog converters and other circuit elements operating on the output sample stream can work at a substantially slower sample rate and narrower signal bandwidth than in predistortion schemes known in the art, in which the expanded bandwidth is maintained throughout. The present invention can thus be made substantially less costly and complex than such schemes. Alternatively or additionally, it can be made to work with signal bandwidths that known predistortion schemes cannot handle with readily available hardware. The sample stream that is output by the predistortion circuit is corrected for distortion by the amplifier within the reduced bandwidth of the predistortion circuit output, but not for additional intermodulation products that typically occur over the rest of the expanded bandwidth. Consequently, the power amplifier may generate substantial distortion products in the wings of the extended bandwidth, outside the reduced-bandwidth region in which the distortion is corrected by the predistortion circuit. The uncorrected distortion products in the wings are preferably suppressed by a bandpass filter at the output of the power amplifier, substantially without affecting the amplified signals within the given bandwidth. Thus, the present invention can be used to correct for distortion that extends over substantially any bandwidth, including intermodulation products both inside and falling partially outside the given bandwidth of the signals. In-band distortion suppression of the amplifier is performed by the predistortion mechanism, whereas the out-of-band distortion is filtered by the band-pass filter. In many applications a band-pass filter or duplexer is already present at the output of the amplifier, so that no extra hardware is needed for this purpose. In some preferred embodiments of the present invention, the digital predistortion circuit operates on baseband signals, whereas in other embodiments, the predistortion circuit is configured to operate on intermediate frequency (IF) signals. The nonlinear correction may be applied to the signals using any suitable form of digital signal processing, including both real- and complex-domain (I/Q or polar) processing. Preferably, the nonlinear correction is applied using a parallel processing architecture, whereby two or more samples are processed simultaneously, in order to accommodate the high sample rate of the expanded bandwidth. In some preferred embodiments of the present invention, digital predistortion as described herein is applied in conjunction with other methods of amplifier linearization, such as feedforward correction of the signals. Most preferably, a feedforward amplifier with digital signal equalization is used, as described in U.S. patent application Ser. No. 09/226,709, which is assigned to the assignee of the present patent application and incorporated herein by reference. There is therefore provided, in accordance with a preferred embodiment of the present invention, linearization circuitry for predistortion of an input signal to an amplifier having a given distortion characteristic, including: a correction circuit, which receives a stream of samples of the input signal at a high sample rate and which applies a correction to the samples responsive to the given distortion characteristic; and a decimation circuit, which receives the corrected samples from the correction circuit and reduces the sample rate of the stream for output to the amplifier, to a reduced rate substantially less than the high sample rate. Preferably, the circuitry includes an interpolator, which receives the stream of samples at an input sample rate less than the high sample rate, and which up-samples the stream to the high sample rate. Further preferably, the correction circuit determines a characteristic of the samples and selects one or more correction coefficients responsive to the characteristic, wherein the one or more correction coefficients preferably include complex coefficients. Preferably, the characteristic of the samples includes a power level thereof. In a preferred embodiment, the correction circuit includes a plurality of parallel processing channels, to which the samples are routed in alternation, wherein at least two of the plurality of processing channels preferably read the coefficients from a common look-up table. Further preferably, each of the parallel processing channels operates on the samples at a sample rate substantially less than the high sample rate. Preferably, the decimation circuit includes a low-pass filter and a decimator. Preferably, the signal output by the circuitry is modulated and amplified by means of the amplifier, and following amplification, the signals are bandpass filtered to suppress distortion products of the amplifier outside a reduced bandwidth corresponding to a Nyquist zone of the reduced sample rate of the filtered stream. Most preferably, the amplifier generates the distortion products over a bandwidth substantially greater than the reduced bandwidth, but generally contained within a high bandwidth corresponding to a Nyquist zone of the high sample rate. Preferably, the high sample rate is at least twice the reduced sample rate, and more preferably at least four times the reduced sample rate. There is also provided, in accordance with a preferred embodiment of the present invention, linearized amplification apparatus for amplifying an input signal, including: digital processing circuitry, which includes: a correction circuit, which receives a stream of samples of the input signal at a high sample rate and applies a predistortion correction to the samples; and a decimation circuit, which receives the corrected samples from the correction circuit and reduces the sample rate of the stream to a reduced rate substantially less than the high sample rate; a modulator, which generates a modulated signal responsive to the sample stream from the digital correction circuitry; and an amplifier, which amplifies the modulated signal, such that distortion in a signal band within a Nyquist zone corresponding to the reduced sample rate is substantially reduced. Preferably, the apparatus includes a low-pass filter, which filters the amplified signal to suppress distortion products outside the signal band. Further preferably, the predistortion correction is determined responsive to a distortion characteristic of the amplifier. Preferably, the apparatus includes a digital/analog converter, which converts the digitally-processed samples to analog signals at the reduced sample rate. There is moreover provided, in accordance with a preferred embodiment of the present invention, a method for linearization of an amplifier having a given distortion characteristic, including: receiving a stream of samples of an input signal, the stream having a high sample rate; applying a predistortion correction to the samples responsive to the given distortion characteristic; reducing the sample rate of the stream of corrected samples to a reduced rate substantially less than the high sample rate; and outputting the corrected, filtered samples for amplification by the amplifier. Preferably, receiving the stream of samples includes receiving a stream of samples having an input sample rate less than the high sample rate and up-sampling the stream to the high sample rate. Further preferably, reducing the sample rate comprises low-pass filtering and decimating the corrected samples. Preferably, outputting the samples includes converting the corrected samples from digital to analog form and modulating the samples at a radio frequency. The present invention will be more fully understood from the following detailed description of the preferred embodiments thereof, taken together with the drawings in which: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram illustrating radio frequency amplifier apparatus including digital predistortion circuitry, in accordance with a preferred embodiment of the present invention; FIGS. 2A-2F are graphs that schematically illustrate spectra of digital signals in the apparatus of FIG. 1; FIGS. 3A-3D are graphs that schematically illustrate spectra of analog signals in the apparatus of FIG. 1; FIG. 4 is a schematic block diagram illustrating a nonlinear correction circuit for use in the apparatus of FIG. 1, in accordance with a preferred embodiment of the present invention; FIG. 5 is a schematic block diagram showing details of predistortion circuitry, in accordance with a preferred embodiment of the present invention; and FIG. 6 is a schematic block diagram showing details of predistortion circuitry, in accordance with another preferred embodiment of the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 is a schematic block diagram illustrating radio frequency amplification apparatus 20 , including digital predistortion circuitry 21 and a power amplifier 34 , in accordance with a preferred embodiment of the present invention. Apparatus 20 receives baseband signals, preferably in the form of a digital stream of I and Q signal samples having a given initial bandwidth, and generates an amplified radio frequency (RF) output to an antenna. The apparatus is particularly suited for use in the context of a wideband, multi-channel amplifier system in a cellular base station and is preferably, although not necessarily, integrated with other amplification and linearization elements as are known in the art. Most preferably, apparatus 20 is integrated with a feedforward amplifier, and particularly with a feedforward amplifier that includes digital equalization, as described in the above-mentioned U.S. patent application. The I and Q baseband signals are input to respective interpolators 22 , which up-sample the signals by an interpolation ratio N 1 , wherein preferably N 1 =2 or 4, and are then filtered by low-pass filters 23 . For each pair of samples, a nonlinear corrector 24 determines a power level and, optionally, other signal characteristics, such as the phase, and applies a predistortion correction responsive to a measure of the distortion introduced by amplifier 34 . The interpolation performed before nonlinear correction effectively expands the processing bandwidth of the correction. Such expansion is generally needed to satisfy the requirement that the predistorted signals be band-limited to within the (expanded) bandwidth in which the nonlinear correction is being performed. Otherwise, aliasing products may be produced. In some applications, however, a certain amount of aliasing is permitted, in which case the predistorted signal may have some spectral density outside the expanded bandwidth, as long as it is no greater than the permitted level. Generally, the nonlinear correction is based on a function which is inverse to the nonlinear distortion of the amplifier. Preferably, the appropriate correction is based on coefficients read from a look-up table (LUT), whose contents are calculated and updated responsive to a feedback sample 38 taken from the amplifier output, as is known in the art. Suitable methods for generating predistortion coefficients are described, for example, in the references cited in the Background of the Invention. Although in preferred embodiments described hereinbelow, the predistortion coefficients are selected based on the signal power, substantially any suitable predistortion function may be used for this purpose. For instance, nonlinear corrector 24 may calculate both magnitude and phase of each complex sample (I,Q pair) and use a two-dimensional LUT to generate correction coefficients as a function of both amplitude and phase. Alternatively, an estimated predistortion polynomial or other computed function may be used instead of a look-up table. Following nonlinear correction, the samples are filtered by low-pass filters 26 and then are decimated by decimators 28 with a decimation ratio N 2 . Although filters 26 and decimators 28 are shown in the figure as separate blocks, it is also possible to implement them in a common filter unit for each of the I and Q channels. Preferably, the decimation ratio N 2 is the same as N 1 , the ratio used in interpolators 22 , so that the output sample rate of predistortion circuitry 21 is reduced to be the same as the input sample rate. The output samples are converted to analog form by digital/analog converters (DACs) 30 and filtered by analog low-pass filters 31 . The reduced output sample rate allows output circuits of predistortion circuitry 21 to be simplified, and similarly reduces substantially the sample rate at which the DACs must operate. In this respect, the present invention differs substantively from digital predistortion schemes known in the art, such as that described in U.S. Pat. No. 4,700,151, in which the full, interpolated sample rate used in predistorting the signals is maintained, and very fast digital/analog conversion is required. Alternatively, it is possible, and sometimes desirable, to use an interpolation ratio N 1 which is different from the decimation ratio N 2 . Having a large interpolation ratio and lower decimation ratio, for example, enables predistortion circuitry 21 to suppress some out-of-band distortion products in addition to the in-band products. The interpolation and decimation ratios may be fixed or variable according to the implementation. The predistorted analog baseband signals output by filters 31 are upconverted to the desired radio frequency by an I/Q modulator 32 , which is driven by a local oscillator. The modulated signals are then amplified by power amplifier 34 . On account of the predistortion effected by circuitry 21 , the output of amplifier 34 is largely free of intermodulation distortion products in and near the frequency band of the modulated signals themselves. Amplifier 34 may also generate distortion products farther outside the signal frequency band, which are not affected by circuitry 21 on account of the limited output sample rate of the circuitry. These out-of-band products are substantially suppressed by a bandpass filter 36 following the amplifier. Reference is now made to FIGS. 2A-2F, which are spectral graphs that schematically illustrate frequency-domain operation of circuitry 21 . In a preferred embodiment of the present invention, the baseband signals input to the circuitry cover a spectral band 40 of 25 MHz (±12.5 MHz), as is typical in cellular systems. The signals are sampled at a rate of 62.5 Msps (million samples per second), so that the Nyquist bandwidth of the complex, sampled signals is 31.25 MHz, giving a “Nyquist zone” of ±31.25 MHz as shown in FIG. 2 A. FIG. 2B shows the spectrum of the samples following up-sampling in interpolators 22 , wherein a value of N 1 =4 is taken. The Nyquist zone now expands to ±125 MHz due to the up-sampling, and a comb of signal replicas 42 is formed alongside band 40 . Low-pass filters 23 remove the undesired replicas, but leave band 40 in the expanded Nyquist zone, as shown in FIG. 2 C. The effect of nonlinear corrector 24 is to generate a broad predistortion band 44 which is generally inverse to the nonlinear distortion of the power amplifier. The wings of band 44 typically extend well beyond the ±31.25 MHz Nyquist zone of the input signals. Therefore, if the predistortion were imposed without first up-sampling and interpolating the signals, the signals would be irretrievably distorted by aliasing effects. After the nonlinear correction has been applied by corrector 24 , however, it is possible to low-pass filter the predistorted signal, as illustrated in FIG. 2 E. Thus, most of the out-of-band portion of signal 44 is removed, except for a portion overlapping with or adjacent to the frequencies of band 40 . The effect of decimators 28 is then to reduce the sampling rate, i.e., to narrow the Nyquist zone back down to ±31.25 MHz, as shown in FIG. 2 F. DACs 30 can thus operate at 62.5 Msps, which is a rate can be achieved by inexpensive, commonly-available commercial components. FIGS. 3A-3D schematically illustrate spectra of analog signals in apparatus 20 , following the digital correction applied by circuitry 21 . FIG. 3A shows the spectrum of the signals following D/A conversion by DACs 30 and upconversion to a carrier frequency f c by modulator 32 . For comparison, FIG. 3B shows the spectrum of amplified signals that would be produced by power amplifier 34 in the absence of predistortion. A broad distortion band 46 is superimposed on signal band 40 . Addition of predistortion band 44 to distortion band 46 , however, removes the distortion in a cancellation region 48 that includes band 40 and adjacent frequencies, as illustrated in FIG. 3 C. Finally, the remainder of the wings of band 46 are suppressed by bandpass filter 36 , leaving only minimal out-of-band distortion 50 , without substantially affecting the amplified signal in band 40 . Apparatus 20 thus achieves linearization of output signals comparable to or better than that of digital predistortion systems operating at the full, up-sampled bandwidth throughout. FIG. 4 is a block diagram that schematically illustrates nonlinear corrector 24 , in accordance with a preferred embodiment of the present invention. Each pair of I and Q samples provided by interpolators 22 is evaluated to determine the instantaneous signal power by an absolute value block 52 . The power determination is used to select a pair of appropriate correction coefficients from a look-up table (LUT) 54 . Both the I and Q samples are multiplied by their respective coefficients in multipliers 56 to provide corrected I and Q outputs to low-pass filter 26 . The entries in LUT 54 are preferably calculated and updated based on feedback sample 38 , as noted hereinabove, and any suitable method known in the art may be used for calculating the coefficients. FIG. 5 is a block diagram that schematically illustrates details of digital predistortion circuitry 21 , in accordance with another preferred embodiment of the present invention. In this case, corrector 24 includes two parallel digital predistorters 58 , each typically comprising a power evaluator and coefficient multipliers as in the corrector circuit of FIG. 4 . The two predistorters preferably share a common LUT 60 . Interpolator 22 (shown here for simplicity as a single block, including the function of low-pass filters 23 , instead of the group of blocks in FIG. 1) up-samples the I and Q inputs, so that the input sample rate to corrector 24 is 125 Msps (equivalent to a complex bandwidth of ±62.5 MHz). The samples are multiplexed between the two predistorters 58 , so that each predistorter need operate only at 62.5 Msps (31.25 Msps×2). The parallel architecture of the circuitry shown in FIG. 5 thus alleviates the need for costly, high-speed digital components. FIG. 6 is a block diagram that schematically illustrates details of circuitry 21 , in accordance with yet another preferred embodiment of the present invention. Here interpolator 22 up-samples the signals by four, to a 250 Msps rate. The samples are multiplexed among four parallel predistorters 62 , each operating at 62.5 Msps. It will thus be observed that the parallel processing architecture of corrector 24 may be adapted to operate at substantially any desired sample rate. Although certain circuit configurations are shown in the figures and described hereinabove by way of illustration, those skilled in the art will understand that the principles of the present invention may be applied using a wide range of different circuit designs, all of which are considered to be within the scope of the present invention. Predistortion circuits based on the present invention may operate in the digital or analog domain, on real or complex (Cartesian or polar) signals, and on baseband or IF signals. They may be integrated with a variety of different amplifier types and linearization architectures and used in different system applications. It will thus be appreciated that the preferred embodiments described above are cited by way of example, and the full scope of the invention is limited only by the claims.

Linearization circuitry for predistortion of an input signal to an amplifier having a given distortion characteristic, including a correction circuit, which receives a stream of samples of the input signal at a high sample rate and which applies a correction to the samples responsive to the given distortion characteristic. The corrected samples are preferably low-pass filtered. A decimation circuit receives the corrected samples from the correction circuit and reduces the sample rate of the stream for output to the amplifier, to a reduced rate substantially less than the high sample rate. The present invention enables significant parts of the circuitry to operate at much lower sample rates that previously achievable and lends itself naturally to parallel implementations.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to switch driver circuitry for use, for example, in digital-to-analog converters. 2. Description of the Related Art FIG. 1 of the accompanying drawings shows parts of a previously-considered current-switched digital-to-analog converter (DAC) 1 . The DAC 1 is designed to convert an n-bit digital input word into a corresponding analog output signal. The DAC 1 includes a plurality of individual binary-weighted current sources 2 1 to 2 n corresponding respectively to the n bits of the digital input word applied to the DAC. Each current source passes a substantially constant current, the current values passed by the different current sources being binary-weighted such that the current source 2 1 corresponding to a least-significant-bit of the digital input word passes a current I, the current source 2 2 corresponding to the next-least-significant-bit of the digital input word passes a current 2 I, and so on for each successive current source of the converter. The DAC 1 further includes a plurality of differential switching circuits 4 1 to 4 n corresponding respectively to the n current sources 2 1 to 2 n . Each differential switching circuit 4 is connected to its corresponding current source 2 and switches the current produced by the current source either to a first terminal connected to a first connection line A of the converter or a second terminal connected to a second connection line B of the converter. The differential switching circuit receives one bit of the digital input word (for example the differential switching circuit 4 1 receives the least-significant-bit of the input word) and selects either its first terminal or its second terminal in accordance with the value of the bit concerned. A first output current I A of the DAC is the sum of the respective currents delivered to the differential-switching-circuit first terminals, and a second output current I B of the DAC is the sum of the respective currents delivered to the differential-switching-circuit second terminals. The analog output signal is the voltage difference V A -V B between a voltage V A produced by sinking the first output current I A of the DAC 1 into a resistance R and a voltage V B produced by sinking the second output current I B of the converter into another resistance R. FIG. 2 shows a previously-considered form of differential switching circuit suitable for use in a digital-to-analog-converter such as the FIG. 1 converter. This differential switching circuit 4 comprises first and second PMOS field effect transistors (FETs) S 1 and S 2 . The respective sources of the transistors S 1 and S 2 are connected to a common node TAIL to which a corresponding current source ( 2 1 to 2 n in FIG. 1) is connected. The respective drains of the transistors S 1 and S 2 are connected to respective first and second output nodes OUTA and OUTB of the circuit which correspond respectively to the first and second terminals of each of the FIG. 1 differential switching circuits. Each transistor S 1 and S 2 has a corresponding driver circuit 6 1 or 6 2 connected to its gate. Complementary input signals IN and INB are applied respectively to the inputs of the driver circuits 6 1 and 6 2 . Each driver circuit buffers and inverts its received input signal IN or INB to produce a switching signal SW 1 or SW 2 for its associated transistor S 1 or S 2 such that, in the steady-state condition, one of the transistors S 1 and S 2 is on and the other is off. For example, as indicated in FIG. 2 itself, when the input signal IN has the high level (H) and the input signal INB has the low level (L), the switching signal SW 1 (gate drive voltage) for the transistor S 1 is at the low level L, causing that transistor to be ON, whereas the switching signal SW 2 (gate drive voltage) for the transistor S 2 is at the high level H, causing that transistor to be OFF. Thus, in this condition, all of the input current flowing into the common node TAIL is passed to the output node OUTA and no current passes to the output node OUTB. When it is desired to change the state of the circuit 4 of FIG. 2 so that the transistor S 1 is OFF and the transistor S 2 is ON, complementary changes are made simultaneously in the input signals IN and INB such that the input signal IN changes from H to L at the same time as the input signal INB changes from L to H. As a result of these complementary changes, it is expected that the transistors S 1 and S 2 will switch symmetrically, that is that the transistor S 1 will turn OFF at exactly the same moment that the transistor S 2 turns ON. However, in practice there is inevitably some asymmetry in the turn-ON and turn-OFF speeds. This can result in a momentary glitch at the common node TAIL which may in turn cause glitches at one or both output nodes of the circuit, producing a momentary error in the DAC analog output value until all of the switches have switched completely. These glitches in the analog output signal may be code-dependent and result in harmonic distortion or even non-harmonic spurs in the output spectrum. As the size of the glitch associated with the switching of the differential switching circuit is dependent on the symmetry of the complementary changes in the input signals IN and INB, much attention has been directed to generating and delivering these input signals to the differential switching circuit synchronously with one another. However, it is found in practice that, even if the input signals are perfectly symmetrical, the drive circuits 6 1 and 6 2 which derive the switching signals from the input signals inevitably introduce asymmetry into the switching signals SW 1 and SW 2 which actually control the transistors S 1 and S 2 . Such asymmetry results in transient output current distortion in any individual differential switch circuit. Furthermore, in a DAC employing multiple differential switch circuits, it also results in a variation between the switching times of the different circuits. These variations lower the spurious-free dynamic range (SFDR) of the DAC (a measure of the difference, in dB, between the rms amplitude of the output signal and the peak spurious signal over the specified bandwidth). These variations also lead to code-dependency of the analog output signal of the converter. SUMMARY OF THE INVENTION According to a first aspect of the present invention there is provided switch driver circuitry comprising: first and second output nodes; a current-voltage converter connected to said first and second output nodes to provide a current path through which current is permitted to flow in a first direction from said first to said second output node, or in a second direction from said second to said first output node, when the circuitry is in use, for producing a potential difference between said first and second output nodes that is dependent upon the magnitude and direction of the current flow; and switching circuitry connected with said first and second output nodes and switchable, in dependence upon an applied control signal, from a first state, in which a current of preselected magnitude is caused to flow in said first direction through said current path, to a second state in which a current of substantially the same magnitude as said preselected magnitude is caused to flow in said second direction through said current path, a current-voltage characteristic of the current-voltage converter being such that said potential differences produced respectively in said first and second states have substantially the same magnitudes but opposite polarities. Such switch driver circuitry can provide improved symmetry of operation. According to a second aspect of the present invention there is provided a switch circuit comprising: first and second output nodes; a current-voltage converter connected to said first and second output nodes to provide a current path through which current is permitted to flow in a first direction from said first to said second output node, or in a second direction from said second to said first output node, when the circuitry is in use, for producing a potential difference between said first and second output nodes that is dependent upon the magnitude and direction of the current flow; switching circuitry connected with said first and second output nodes and switchable, in dependence upon an applied control signal, from a first state, in which a current of preselected magnitude is caused to flow in said first direction through said current path, to a second state in which a current of substantially the same magnitude as said preselected magnitude is caused to flow in said second direction through said current path, a current-voltage characteristic of the current-voltage converter being such that said potential differences produced respectively in said first and second states have substantially the same magnitudes but opposite polarities; a first switch element having a control terminal connected to said first output node and switchable from an OFF state to an ON state by the change in the first-output-node potential brought about when said switching circuitry is switched from one of said first and second states to the other of those states; and a second switch element having a control terminal connected to said second output node and switchable from an ON state to a OFF state by the change in the second-output-node potential brought about when said switching circuitry is switched from said one state to said other state. According to a third aspect of the present invention there is provided a digital-to-analog converter comprising switch driver circuitry comprising: first and second output nodes; a current-voltage converter connected to said first and second output nodes to provide a current path through which current is permitted to flow in a first direction from said first to said second output node, or in a second direction from said second to said first output node, when the circuitry is in use, for producing a potential difference between said first and second output nodes that is dependent upon the magnitude and direction of the current flow; switching circuitry connected with said first and second output nodes and switchable, in dependence upon an applied control signal, from a first state, in which a current of preselected magnitude is caused to flow in said first direction through said current path, to a second state in which a current of substantially the same magnitude as said preselected magnitude is caused to flow in said second direction through said current path, a current-voltage characteristic of the current-voltage converter being such that said potential differences produced respectively in said first and second states have substantially the same magnitudes but opposite polarities; the digital-to-analog converter further comprising: a first switch element having a control terminal connected to said first output node and switchable from an OFF state to an ON state by the change in the first-output-node potential brought about when said switching circuitry is switched from one of said first and second states to the other of those states; a second switch element having a control terminal connected to said second output node and switchable from an ON state to a OFF state by the change in the second-output-node potential brought about when said switching circuitry is switched from said one state to said other state, said first switch element being connected between first and second converter nodes and said second switch element being connected between said first node and a third converter node; and a current source or current sink connected operatively to said first converter node for causing a substantially constant current to pass through said first converter node when the converter is in use. According to a fourth aspect of the present invention there is provided a digital-to-analog converter comprising: a plurality of differential switching circuits, each differential switching circuit having switch driver circuitry comprising: first and second output nodes; a current-voltage converter connected to said first and second output nodes to provide a current path through which current is permitted to flow in a first direction from said first to said second output node, or in a second direction from said second to said first output node, when the circuitry is in use, for producing a potential difference between said first and second output nodes that is dependent upon the magnitude and direction of the current flow; switching circuitry connected with said first and second output nodes and switchable, in dependence upon an applied control signal, from a first state, in which a current of preselected magnitude is caused to flow in said first direction through said current path, to a second state in which a current of substantially the same magnitude as said preselected magnitude is caused to flow in said second direction through said current path, a current-voltage characteristic of the current-voltage converter being such that said potential differences produced respectively in said first and second states have substantially the same magnitudes but opposite polarities; each said differential switching circuit further having: a first switch element having a control terminal connected to said first output node and switchable from an OFF state to an ON state by the change in the first-output-node potential brought about when said switching circuitry is switched from one of said first and second states to the other of those states; a second switch element having a control terminal connected to said second output node and switchable from an ON state to a OFF state by the change in the second-output-node potential brought about when said switching circuitry is switched from said one state to said other state, said first switch element being connected between first and second nodes of the differential switching circuit and said second switch element being connected between said first node and a third node of the differential switching circuit; and the respective second nodes of the differential switching circuits of said plurality being connected together, and the respective third nodes of the differential switching circuits of said plurality being connected together; and the digital-to-analog converter further comprising a plurality of current sources or current sinks, corresponding respectively to the differential switching circuits of said plurality, each current source or current sink being connected operatively to said first node of its said corresponding differential switching circuit for causing a substantially constant current to flow therethrough when the converter is in use. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, discussed hereinbefore, shows parts of a previously-considered current-switched DAC; FIG. 2 shows parts of previously-considered switch driver circuitry in the FIG. 1 DAC; FIG. 3 shows parts of switch driver circuitry according to a first embodiment of the present invention; FIG. 4 shows an example of current switching circuitry to which the FIG. 3 embodiment can be connected; FIGS. 5 (A) to 5 (D) show operating waveforms generated by the FIG. 3 embodiment when in use; FIGS. 6 (A) and 6 (B) are diagrams for use respectively in explaining operation of the FIG. 3 embodiments in first and second different states; FIG. 7 shows a graph for use in explaining a current-voltage characteristic of a circuit element in the FIG. 3 embodiment; FIG. 8 shows a modification which can be applied to embodiments of the invention; and FIG. 9 shows parts of switch driver circuitry according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows parts of switch driver circuitry according to a preferred embodiment of the present invention. The circuitry 10 includes respective first and second inverting input buffers 12 and 14 . The first input buffer receives at an input thereof a first input signal IN and the second input buffer 14 receives at an input thereof a second input signal INB complementary to the first input signal IN. The first input buffer 12 inverts the received IN signal to produce at an output thereof an inverted signal INVB. Similarly, the second input buffer 14 inverts the received INB signal to produce at an output thereof an inverted signal INV. The signals IN, INB, INV and INVB are all logic signals which change between a high logic level (H) and a low logic level (L). The inverted signal INVB is supplied from the output of the first input buffer 12 to an input of a first inverting output buffer 16 . As shown in FIG. 3, the output buffer 16 includes respective PMOS FET and NMOS FET transistors 18 and 20 . The PMOS FET transistor 18 has its source connected to a first common node CN 1 of the circuitry, its gate connected to the output of the first input buffer 12 and its drain connected to a first output node ON 1 of the circuitry. The NMOS FET 20 has its source connected to the first output node ON 1 , its gate connected to the output of the first input buffer 12 , and its drain connected to a second common node CN 2 of the circuitry. The circuitry also includes a second inverting output buffer 22 which, like the first output buffer 16 , has respective series-connected PMOS FET and NMOS FET transistors 24 and 26 . The PMOS FET 24 has its source connected to the first common node CN 1 , its gate connected to the output of the second input buffer 14 , and its drain connected to a second output node ON 2 of the circuitry. The NMOS FET 26 has its source connected to the second output node ON 2 , its gate connected to the output of the second input buffer 14 , and its drain connected to the second common node CN 2 . Connected between a positive supply line ANALOG VDD and the first common node CN 1 of the circuitry are a constant current source transistor 28 and a cascode transistor 30 . Each of the transistors 28 and 30 is a PMOS FET. The constant current source transistor 28 has its gate connected to a first biassing line B 1 of the circuitry which, in use of the circuitry, is maintained at a potential V pcs that is fixed relative to the potential of the positive supply line ANALOG VDD. The cascode transistor 30 has its gate connected to a second biassing line B 2 of the circuitry which, in use of the circuitry, is maintained a potential V pcasc which is also fixed in relation to ANALOG VDD potential. Connected between the second common node CN 2 of the circuitry and a ground potential supply line GND of the circuitry are series-connected first and second resistors R 1 and R 2 and, in parallel with the resistors, a capacitor C 1 . The resistors R 1 and R 2 have a total resistance of approximately 5 kΩ in this embodiment, with a 1:2 resistance ratio. The capacitor C 1 has a capacitance of, for example, 100 fF in this embodiment. Connected between the first and second output nodes ON 1 and ON 2 of the circuitry 10 is a further PMOS FET 32 . The PMOS FET 32 has first and second current-path terminals connected respectively to the first and second output nodes ON 1 and ON 2 . One of the first and second current-path terminals is the source of the FET and the other of the current-path terminals is the drain of the FET, the source and drain designations being dependent on the in-use potentials of the output nodes. Following convention, the higher-potential current-path terminal for a PMOS FET is designated the source, and the lower-potential current-path terminal is designated the drain. As will be explained hereinafter, these designations are swapped around in use of the circuitry. The gate of the transistor 32 is connected to a junction node JN between the first and second resistors R 1 and R 2 . As shown in FIG. 4, the FIG. 3 circuitry may be used to drive current switching circuitry of the same kind as described already with reference to FIG. 2 . Accordingly, a description of the current switching circuitry is not repeated here. The first main switching transistor S 1 in FIG. 4 has its gate connected to the first output node ON 1 of the FIG. 3 switch driver circuitry, and the second main switching transistor S 2 in FIG. 4 has its gate connected to the second output terminal ON 2 of the FIG. 3 switch driver circuitry. As indicated by the parts shown with dotted lines in FIG. 4, each branch of the current switching circuitry preferably includes a cascode transistor 42 or 44 connected between the main switching transistor S 1 or S 2 of the branch and the output terminal OUTA or OUTB of the branch. These optional cascode transistors are described more fully in our co-pending U.S. patent application Ser. No. 09/634,588 (corresponding to United Kingdom patent application no. 9926653.8), the entire content of which is incorporated herein by reference. The cascode transistor 42 or 44 in each branch has its source connected to the drain of the main switching transistor S 1 or S 2 of the branch concerned, its gate connected to the ground potential supply line GND, and its drain connected to the output terminal OUTA or OUTB of the branch concerned. Operation of the FIG. 3 and FIG. 4 circuitry will now be described with reference to FIGS. 5 (A) to 5 (D) and 6 (A) and 6 (B). Incidentally, to make the timing relationships between the various signals easier to see in FIGS. 5 (A) to 5 (D), FIG. 5 (B) is repeated as FIG. 5 (C). Initially, i.e. prior to time A in FIGS. 5 (A) to 5 (D), the first input signal IN has the low logic level L, and the second input signal INB has the high logic level H. This means that the inverted signals INVB and INB are H and L respectively. In this condition, as shown in FIG. 6 (A), in the first output buffer 16 the PMOS FET 18 is OFF and the NMOS FET 20 is ON. In the second output buffer 22 , the PMOS FET 24 is ON and the NMOS FET 26 is OFF. The constant current source transistor 28 supplies a substantially constant current I from the positive supply line ANALOG VDD to the first common node CN 1 . The current I is, for example, 150 μA. The current I passes through the cascode transistor 30 which serves to shield the drain of the current source transistor 28 from voltage fluctuations caused by fluctuations in the potential of the first common node CN 1 arising in use of the circuitry. Thus, the current I supplied to the first common node CN 1 has a first path P 1 between the first and second common nodes, as shown in FIG. 6 (A). This path passes (in order) through the channel of the PMOS FET 24 , the second output node ON 2 , the channel of the PMOS FET 32 , the first output node ON 1 , and the channel of the NMOS FET 20 . From the second common node CN 2 , the current I then passes through the resistor R 1 , the junction node JN and the second resistor R 2 , to reach the ground potential reference line GND. The potentials generated at the various circuitry nodes in this condition are as follows (see FIG. 5 (B)). The potential V JN of the junction node JN is determined by the product I.R 2 of the current I and the resistance of the second resistor R 2 which, in this embodiment, is approximately 0.36V. Similarly, the potential V CN2 of the second common node CN 2 is determined by I(R 1 +R 2 ) which, in this embodiment, is approximately 0.55V. The potential V ON1 of the first output node ON 1 is determined by the sum of the drain potential of the NMOS FET 20 and the on-state drain-source voltage of the NMOS FET 20 , i.e. V ON1 =V CN2 +V DS(ON)20 . In this embodiment, V DS(ON)20 is approximately 50 mV, so that V ON1 is approximately 0.60V. The current I flows through the PMOS FET 32 from the second output node ON 2 to the first output node ON 1 . This means that the source of the transistor 32 (i.e. its higher-potential current-path terminal) is connected to the second output node ON 2 , and its drain is connected to the first output node ON 1 . The current I flowing through the transistor 32 is set high enough to place the transistor 32 in a saturated operating region. In this case, the gate-source voltage V GS32 of the transistor 32 has an unique value determined by the current density in the transistor 32 , i.e. V GS32 =V TP −(I/k), where I is the current flowing through the transistor 32 and V TP and k are parameters of the transistor 32 determined by its physical structure. For example, V GS32 is approximately −0.9V in this embodiment. To obtain the source potential of the transistor 32 it is necessary to subtract this gate-source voltage V GS32 from the gate voltage of the transistor 32 . This source potential of the transistor 32 determines the potential V ON2 of the second output node. Thus, V ON2 =V JN −V GS32 . In this embodiment, with V JN ≈0.36V and V GS32 ≈−0.90V, V ON2 is approximately equal to 1.25V. The potential V CN1 of the first common node CN 1 is determined by the source potential of the PMOS FET 24 . This source potential is in turn determined by the drain potential of the PMOS FET 24 , i.e. V ON1 , and the ON-state drain-source voltage V DS(ON)24 of the PMOS FET 24 . Thus, V CN1 =V ON2 −V DS(ON)24 . Typically, V DS(ON)24 is approximately −150 mV, so that V CN1 is approximately equal to 1.40V in this embodiment. In this condition (FIG. 6 (A)) the first output node ON 1 has a predetermined ON output potential V on of the circuitry, and the second output node ON 2 has a predetermined OFF output potential V OFF of the circuitry, i.e. V ON1 =V on and V ON2 =V off . In this embodiment, V on ≈0.60V and V off ≈1.25V. When these potentials are applied to the switching transistors S 1 and S 2 in the current switching circuitry, the transistor S 1 , which receives the ON output potential V on , is turned ON, and the switching transistor S 2 , which receives the OFF output potential V off , is turned OFF. As a result, the potential difference V B −V A between the output terminals OUTB and OUTA is negative, as shown in FIG. 5 (D). Incidentally, the other potential differences V CASCB −V CASCA and V B ′−V A ′ shown in FIG. 5 (D) are internal signals within the current switching circuitry and will not be discussed further here. At time A in FIGS. 5 (A) to 5 (D) the first and second input signals IN and INB undergo respective complementary logic level changes (L to H for IN, and H to L for INB). In response to these changes the input buffer output signals INV and INVB also undergo complementary logic level changes (L to H for INV and H to L for INVB). As a result, as shown in FIG. 6 (B), a second current path P 2 between the common nodes CN 1 and CN 2 is created, different from the first current path P 1 shown in FIG. 6 (A). In this case, the current I supplied to the first common node CN 1 by the constant current source transistor 28 flows through the channel of the PMOS FET 18 in the first output buffer 16 , the first output node ON 1 , the PMOS FET 32 , the second output node ON 2 the and channel of the NMOS FET 26 in the second output buffer 22 . As in FIG. 6 (A), from the second common node CN 2 the current flows through the resistor R 1 , the junction node JN and the second resistor R 2 , before reaching the ground potential supply line GND. After switching has taken place, it will be appreciated that the potentials V CN1 and V CN2 of the common nodes are substantially unchanged from those prevailing before the switching took place, i.e. the potentials of the common nodes are the same in FIGS. 6 (A) and 6 (B). This is because the same current I flows through the second current path P 2 in FIG. 6 (B) as flows through the first current path P 1 in FIG. 6 (A). Also, substantially the same ON and OFF output potentials V on and V off are generated in FIG. 6 (B) as were generated in FIG. 6 (A). In FIG. 6 (B), however, the ON output potential V on is generated at the second output node ON 2 , and the OFF output potential is generated at the first output node ON 1 , i.e. V ON1 =V off and V ON2 =V on . It will also be appreciated that in FIG. 6 (B), the same current I flows through the transistor 32 as flowed in the FIG. 6 (A) case, but in the opposite direction, i.e. from the first output node ON 1 to the second output node ON 2 in FIG. 6 (B). The current-voltage characteristic of the transistor 32 is shown in FIG. 7 . In FIG. 7, the vertical axis represents current flowing through the transistor channel, and the horizontal axis represents the potential difference between the first and second current-path terminals (i.e. the potential difference across the transistor channel). As can be seen from FIG. 7, the I-V characteristic is perfectly symmetrical for both positive and negative values of the current flowing through the transistor, i.e. whichever direction the current is flowing. This means that the potential difference ΔV between the ON and OFF output potentials in FIGS. 6 (A) and 6 (B) is exactly the same. Furthermore, during switching, the potentials at the first and second output nodes ON 1 and ON 2 of the circuitry have the same rising and falling waveforms when switching (at time A) from the state shown in FIG. 6 (A) to the state shown in FIG. 6 (B) as when switching (at time B) from the state shown in FIG. 6 (B) to the state shown in FIG. 6 (A). This effect can clearly be seen from a comparison of the waveforms at times A and B in FIG. 5 (B). The FETs 18 , 20 , 24 and 26 in the output buffers 16 and 22 are desirably very small to provide for fast switching. As a consequence of their small sizes, they tend not to be closely matched. The implications of the mismatches in terms of both delay variation and amplitude variation of the ON and OFF potentials will now be considered. In terms of delay variation, because the FETs in the switch driver circuitry are very small the rise and fall times of the output node potentials are very fast (see FIG. 5 (B)). This means that although there will be delay mismatches between the FETs of the switch driver circuitry, the magnitude of the resulting delay variation at the output nodes is also very small. In terms of amplitude variation the PMOS FETs 18 and 24 do not influence the output potentials, and so if they are not matched there is no significant impact on the symmetry of the output potentials. The NMOS FETs 20 and 26 affect the output potentials only weakly (because although V on is influenced by V DS(ON) of the NMOS FET 20 or 26 that is on, V DS(ON) is itself small, e.g. 50 mV). The ON and OFF output potentials therefore only have a very small asymmetry due to mismatches of the transistors in the output buffers. The capacitor C 1 is a decoupling capacitor provided to make the potential V TAIL in the current switching circuitry settle as fast as possible. Referring to FIG. 5 (B) it can be seen that when switching occurs, V TAIL has a small rise. This rise is caused by the transient at the second common node CN 2 that occurs during switching. In order to make V TAIL settle as quickly as possible it is desirable to reduce the CN 2 transient. This is achieved, at the expense of a larger transient at the first common node CN 1 , by means of the capacitor C 1 coupled between CN 1 and GND. The transient on CN 1 does not affect the current switching circuitry, and is therefore insignificant. The capacitance value is preferably set to provide a time constant of around 500 ps, similar to the settling times of the internal signals of the switch driver circuitry. Thus, when the sum of R 1 and R 2 is approximately 5 kΩ, C 1 should have a capacitance of approximately 100 fF (giving a RC time constant of 500 ps). The transistor 32 also provides the following further advantages. Firstly, as it has a non-linear I-V characteristic, the voltage developed across it is relatively large even when the current flowing through the channel is relatively low, as occurs during switching (i.e. before and after the crossover of the rising and falling waveforms in FIG. 5 (B). This leads to a very fast settling time for the output node potentials after switching, because most of the switch driver current I is available for driving the output nodes rather than being wasted in the transistor 32 . For example, in FIG. 5 (B) it can be seen that the rising waveform, which is slower than the falling waveform, settles in approximately 600 ps. Thus, in the FIG. 3 switch driver circuitry, all of the internal signals settle in less than 600 ps. The effect of applying these fast-settling internal signals to the FIG. 4 current switching circuitry is illustrated in FIG. 5 (D). In FIG. 5 (D), it is assumed that the cascode transistors 42 and 44 are present. The resulting rise time of the potential difference between the output terminals OUTA and OUTB is approximately 350 ps (for the rise from 10% to 90% of full-scale value). This can provide an output bandwidth of 1 GHz, facilitating a typical sampling rate F DAC of the DAC of 1.6 G samples/s with a worst-case rate of 1 G samples/s. The second advantage is that, because the transistor 32 is a PMOS FET like the transistors in the current switching circuitry of FIG. 4, its saturation drain-source voltage V DS(SAT) varies in the same way as the drain-source saturation voltages V DS(SAT) of the transistors in the current switching circuitry. This is important, as in practice, the drain-source saturation voltage V DS(SAT) of a PMOS transistor may vary by a factor of 2 due to process and/or temperature variations. Considering the FIG. 4 current switching circuitry in more detail, at any given time, one of the main switching transistors S 1 and S 2 is OFF and the other is ON. Referring to FIG. 6 (B), for the purposes of explanation it will be assumed that the OFF transistor is the transistor S 1 and the ON transistor is the transistor S 2 . In this condition, the potential V TAIL of the sources of the transistors S 1 and S 2 is influenced by the drain-source potential of the ON transistor S 2 . When the switching transistors S 1 and S 2 have a relatively high drain-source saturation voltage V DS(SAT)S VTAIL is increased as compared to when V DS(SAT)S is low. This means that in order to maintain the OFF transistor S 1 in the OFF condition, its gate voltage, i.e. the OFF potential V OFF , must also be increased. This increase occurs automatically in the FIG. 3 switch driver circuitry because in that circuitry the difference between the OFF and ON potentials is increased when the drain-source saturation voltage V DS(SAT)32 of the transistor 32 is relatively high as compared to when that drain-source saturation voltage is relatively low. Accordingly, the OFF potential is self-regulating in the FIG. 3 switch driver circuitry. In the FIG.3 circuitry it is also desirable to make the ON output potential track V DS(SAT)32 of the switching transistors S 1 and S 2 and the cascode transistors 42 and 44 (if used) in the current switching circuitry. Considering FIG. 6 (A), and assuming the cascode transistors are present, in the branch of the current switching circuitry that is on, the ON output potential V on must be sufficient for both the cascode transistor 42 and the switching transistor S 1 to be maintained in the saturated condition, even when V DS(SAT) of each of those transistors varies. The nominal drain-source saturation voltage V DS(SAT)S of the switching transistors is, for example, 200 mV. The nominal drain-source saturation voltage V DS(SAT)C of the cascode transistors is, for example 300 mV. By setting V on to a nominal value of 0.6V the potential difference between the cascode transistor gate (GND) and the switching transistor gate (V on ) exceeds V DS(SAT)C by 1.5 times the nominal V DS(SAT)S of the switching transistor. However, as V DS(SAT)S and V DS(SAT)C can each vary by a factor of 2 with process/temperature, preferably V on should also increase when V DS(SAT)S and/or V DS(SAT)C increase. This change in V on to compensate for variations in V DS(SAT)S of the switching transistors S 1 and S 2 (and for variations in V DS(SAT)C of the cascode transistors 42 and 44 , if provided) can be achieved by making the resistances of the resistors R 1 and R 2 in the FIG. 3 circuitry variable in dependence upon V DS(SAT)S and/or V DS(SAT)C . One example of control circuitry for varying the resistances will now be described with reference to FIG. 8 . In FIG. 8 the control circuitry 60 includes a first constant current source 62 connected between a positive power supply line ANALOG VDD of the circuitry and a first node N 1 . A first PMOS FET 64 has its source connected to the node N 1 and its gate and drain connected to the ground potential supply line GND. The circuitry also includes a second PMOS FET 66 which has its source connected to the node N 1 . The gate and drain of the PMOS FET 66 are connected to a second node N 2 , and a constant current sink 68 is connected between the node N 2 and GND. The current I 1 sourced by the constant current source 62 is large compared to the current I 2 sunk by the constant current sink 68 . Also, the first PMOS FET 64 is narrow compared to the second PMOS FET 66 . For example, the width of the FET 64 is w and the width of the FET 66 is 3 w, and I 1 =4I sw and I 2 =I sw , where I sw is the current which flows through each switching transistor S 1 or S 2 when ON. The circuitry 60 further includes a high-output-resistance transconductance amplifier 70 having a first (negative) input connected to the node N 2 . A second (positive) input of the amplifier 70 is connected to a node N 3 of the circuitry. A second constant current source 72 is connected between the ANALOG VDD and the node N 3 . First and second NMOS FETs 74 and 76 are connected in series between the node N 3 and GND. The first NMOS FET 74 has its drain connected to the node N 3 , its gate connected to the output of the amplifier 70 and its source connected to the drain of the second NMOS FET 76 . The NMOS FET 76 has its gate connected to the output of the amplifier 70 and its source connected to GND. An output node N 4 of the circuitry 60 is connected to the output of the amplifier 70 . To enable the resistances of the resistors R 1 and R 2 in the switch driver circuitry to be varied, the resistors R 1 and R 2 are implemented using respective first and second series-connected NMOS FET transistors 80 and 82 . The first NMOS FET 80 has its drain connected to the second common node CN 2 of the switch driver circuitry 10 , its gate connected to the output node N 4 of the control circuitry and its source connected to the junction node JN (gate of the transistor 32 ) in the switch driver circuitry 10 . The NMOS FET 82 has its drain connected to the junction node JN, its gate connected to the output node N 4 and its source connected to GND. In this embodiment the NMOS FET 80 has the same size as the NMOS FET 74 and the NMOS FET 82 has the same size as the NMOS FET 76 . Alternatively, there may be a predetermined scaling factor between the two FETS 74 / 80 and 76 / 82 of each pair. The output node N 4 can also be connected to resistance-setting NMOS FETs in further segments of the DAC circuitry, so as to enable the control circuitry 60 to operate in common for all segments. Operation of the FIG. 8 control circuitry will now be described. The elements 62 to 68 serve to generate at the node N 2 a potential V DS(SAT)P which is a measure of the drain-source saturation voltage of the switching transistors in the current switching circuitry (FIG. 3 ). Because of the difference in currents flowing through the FETs 64 and 66 , and their different widths, the ratio of the current densities in the FETs 64 and 66 is 9:1 (=(I 1 -I 2 )/w:I 2 /3 w). Because V DS(SAT) is proportional to the square root of current density, the ratio between the respective V DS(SAT) s of the FETs 64 and 66 is 3:1. The respective V T s of the FETs 64 and 66 are substantially the same. The potential at node N 1 becomes equal to V DS(SAT)64 +V T64 , where the drain-source saturation voltage V DS(SAT)64 of the FET 64 is e.g. 0.9V and the threshold voltage V T64 of the FET 64 is e.g. 1V. Thus, the potential V N1 of node N 1 is, for example, 1.9V. The voltage drop across the FET 66 is V DS(SAT)66 +V T66 , where V DS(SAT)66 is e.g. 0.3V and V T66 is e.g. 1V, i.e. 1.3V. Thus, the potential at node N 2 is approximately equal to V DS(SAT)64 −V DS(SAT)66 , and this potential is taken as the measure V DS(SAT)P of drain-source saturation voltages of the switching and cascode transistors in the current switching circuitry. Incidentally, because the measure V DS(SAT)P is derived from the difference V DS(SAT)64 −V DS(SAT)66 between the respective V DS(SAT) s of two FETs 64 and 66 , it is possible that it will not accurately reflect the actual V DS(SAT) s of the FETs of interest in the current switching circuitry, i.e. the switching transistors and the cascode transistors (if used). However, if it is expected that the actual V DS(SAT) s of the FETs of interest will be, say, 0.6V in total, then it is preferable to set the conditions of the FETs 64 and 66 so that their respective V DS(SAT) s are offset equally on either side of that total actual V DS(SAT) , which is why in this example V DS(SAT)64 is set to 0.9V and V DS(SAT)66 is set to 0.3V. The second constant current source 72 sources a current I 3 that in this embodiment is substantially equal to the current I sourced by the constant current source 24 in the switch driver circuitry of FIG. 3 . In this embodiment the NMOS FET 74 has the same (variable) resistance as the NMOS FET 80 is to provide the first resistor R 1 . Similarly, the second NMOS FET 76 has the same (variable) resistance as the NMOS FET 82 used to provide the resistor R 2 . This means that the voltage at the node N 3 is the same as the voltage V CN2 at the second common node CN 2 in the switch driver circuitry. The effect of the amplifier 70 , therefore, is to adjust the potential at the output node N 4 until the potential at the node N 3 is equal to the potential V DS(SAT)P of the node N 2 . Changing the N 4 -node potential changes the potential at the node N 3 because the N 4 -node potential determines the respective resistances of the first and second NMOS FET transistors 74 and 76 in the control circuitry. In this way, in this embodiment the potential V CN2 of the second common node CN 2 is set substantially equal to the measure V DS(SAT)P . It will be appreciated that, in the FIG. 8 circuitry, the resistances of the resistors R 1 and R 2 (provided by the NMOS FETs 80 and 82 ) each vary in accordance with the potential at the node N 4 . Accordingly, as V CN2 is varied the potential variation at the junction node JN tracks the potential variation of the second common node CN 2 so as to maintain the gate potential of the transistor 32 as a substantially fixed proportion (e.g. ⅔) of the potential V CN2 . The advantage of using the FIG. 8 control circuitry to adjust the potential of the second common node CN 2 is that the ON output potential V on tracks V DS(SAT) variations of the main switching transistors and (if used) the cascode transistors in the current switching circuitry. The PMOS FET 32 serves automatically to cause V OFF to track V DS(SAT) . It will also be appreciated that in place of the PMOS FET 32 in the FIG. 3 embodiment, other circuit elements can be connected between the first and second output nodes ON 1 and ON 2 of the circuitry to achieve the same basic current-voltage conversion effect. In each case, it is preferable that the circuit element used has the same I-V characteristic irrespective of the direction of current flow through the element concerned. The I-V characteristic of the circuit element is preferably non-linear so as to provide a higher resistance at low values of current and a lower resistance at high values of current, but a linear circuit element such as an ohmic resistance element could be used. A second embodiment of the present invention, using an ohmic resistance element between the first and second output nodes, will now be described with reference to FIG. 9 . In FIG. 9, components that are the same as, or correspond closely to, components in the first embodiment of FIG. 3 have been denoted by the same reference numerals and an explanation thereof is omitted. In the FIG. 9 embodiment, in place of the transistor 32 , a resistor 102 is connected between the first and second output nodes ON 1 and ON 2 . A further resistor 104 is connected between ANALOG VDD and the source of the constant current source transistor 28 . Also, a further resistor 106 is connected between the second common node CN 2 and GND in place of the series-connected resistors R 1 and R 2 in the first embodiment. Each of the resistors 102 , 104 and 106 is an ohmic resistance element, for example a high-resistance n-diffusion resistor. As in the first embodiment, the same current I that is sourced by the constant current source transistor 28 flows selectively either along a first current path P 1 , or along a second current path P 2 , through the circuitry, in dependence upon the state of the complementary input signals IN and INB. As in the first embodiment, the potential V CN2 of the second common node is determined by the product of the current I and the resistance R 106 of the resistor 106 . In the second embodiment, the potential difference ΔV between the potentials of the first and second output nodes V ON1 and V ON2 is determined by the product of the current I and the resistance R 102 of the resistor 102 . The I-V characteristic of the resistor 102 is the same for both directions of current flow through it, so the potential difference ΔV is the same whichever state the circuitry is in (in the steady-state) The resistor 104 is provided to cause the potential V S28 of the source of the current source transistor 28 to track changes in the resistance of the resistor 102 . Within the circuitry, the resistors 102 and 104 are preferably placed physically close to one another so that their resistances will have a substantially fixed ratio irrespective of variations in their resistances brought about by process and/or temperature variations. Such variations may exhibit “gradients” across the device in one or more directions as the segments are laid out in a certain pattern over the device substrate. The make the layout within each segment insensitive to such gradients (at least in one direction) the resistor 104 may be divided into 2 equally-sized portions on opposite sides respectively of the resistor 102 . This means that the resistor 104 has a common centroid with the resistor 102 . Then, if the resistance of the resistor 102 in a segment has an increased value, so will the resistance of the resistor 104 of that segment. This has the effect of lowering the potential V S28 at the source of the constant current source transistor 28 so that, assuming its gate potential V pcs remains unchanged (relative to ANALOG VDD), its gate-source voltage is made less negative, thereby reducing the current I. In this way, the product I.R 102 , which defines ΔV, is left substantially unchanged despite the increase in R 102 . The ratios of the resistances R 102 , R 104 and R 106 are, for example, 1:2:1, with I being approximately 80 μA and R 102 being approximately 7.5 kΩ. This provides a potential difference ΔV between the ON and OFF output potentials of approximately 0.6V. When a resistance element such as the element 102 is used as the current-voltage conversion element it is not essential to use the matching resistance element 104 or, indeed, to carry out any compensation for resistance variation. In this respect, although the potential difference ΔV generated across the resistor 102 is kept substantially fixed by using such compensation, inevitably the change in current affects the circuitry in other ways and, for example, changes the speed of the switching operation of the segment. This may make it preferable to leave the current unchanged in response to resistance variations. Comparing FIG. 4 with FIG. 9, a further advantage of the FIG. 4 circuitry over the FIG. 9 circuitry is that the resistance element 102 (and the compensating resistor 104 if used) is large physically compared to the PMOS FET 32 , because a suitably large resistance (e.g. 7.5 kΩ) can only be achieved with a large physical structure (HN resistors may have a resistance of 1 kΩ/square). Such large structures have an appreciable parasitic capacitance. Also, when resistances are used, scaling of the circuitry becomes difficult since, if (say) the current is halved, the resistances must be doubled to achieve the same voltage, whereas with the PMOS FET 32 the voltage across it is maintained when the transistor is halved in size. Even worse, when the resistance is doubled, parasitic capacitance is also doubled, so that compared to the half-size transistors the parasitic capacitance goes up by a factor of 4. This makes the PMOS FET 32 far more preferable to use as the current-voltage conversion element. Although the use of a circuit element having the same I-V characteristic for both directions of current flow between the output nodes is preferable, it will be appreciated that, by using two closely-matched uni-directional circuit elements connected in parallel between the two output nodes, substantially the same effect can be achieved. For example, back-to-back diode elements could be employed between the two output nodes. Each diode could be implemented using an MOS transistor with its gate connected to its source. Although the foregoing embodiments have employed p-channel switching transistors, it will be appreciated that the present invention can be applied in other embodiments to current switching circuitry employing n-channel switching transistors (and a current sink in place of the current source). In this case, the polarities of the supply lines and the conductivity types of the transistors in the switch driver circuitry are reversed. Furthermore, although the present invention has been described in relation to DACs, it will be understood by those skilled in the art that the present invention is applicable to any type of circuitry that includes switch elements that need to switch in complementary manner with accurately-controlled complementary switching signals.

Switch driver circuity having first and second output nodes with a current-voltage converter connected therebetween and providing current paths of first and second directions between the nodes, switching circuity connected therewith being switchable between first and second states respectively permitting current flow of a common preselected magnitude in respective first and second opposite directions producing potential differences between the first and second output nodes of a common magnitude but respective, opposite polarities.

BACKGROUND OF THE INVENTION 1. Technical Field This invention relates generally to a method and apparatus for molding wall units, and in particular to constructing a wall unit having layered discrete veneer components, such as stones, on the outer surface. 2. Background Art Various methods of forming a stone veneer on a single side of a wall unit have heretofore been performed. In one of the related art techniques, a plurality of stones are arranged face-down, forming a single horizontal layer, upon a base surface as discussed in U.S. Pat. No. 1,856,906. The inherent disadvantage of this method is that, since it entails laying the veneer stones horizontally across the bottom of the form, it is limited to producing a stone veneer on only a single surface of the wall unit. Therefore, if a construction design calls for a wall unit having a stone veneer on more than one side, two wall units would have to be constructed separately and positioned back-to-back to produce the desired fixture. Similarly, if a design specified an end unit with a veneer on two or more sides, this would require two or more separate pours, with the attendant increase in manufacturing, shipping, and construction costs. A second related art method is to pre-cast the core with a plurality of discrete attachment anchors (e.g. slots, ties, etc.) and then create the veneer on the previously finished core using a story pole, sandwiching, or other known technique. See, for example, U.S. Pat. No. 5,761,876 to Keady. This process requires at least two separate casting steps or “pours.” Thus, there exists a need for a method which can be used to produce a stone veneer on multiple sides of a wall unit in an efficient and cost effective manner, for instance, in a single pour of concrete. There also exists a related need for a method which can produce stone veneers on multiple curved, sloped, or angled wall unit surfaces. SUMMARY OF THE INVENTION The present invention provides a method for forming a wall unit using a molding technique, comprising: operationally attaching a plurality of panels in an upright manner; arranging two or more layers of discrete veneer components adjacent one of said plurality of panels; filling said volume with a binding material; and subsequent to curing of the binding material, removing said panels. A wall unit form comprising a first surface; a second surface operatively attached to said first surface; end surfaces operatively attached to said first and second surfaces thereby forming an upright form and opposing sides; and optionally, a pocket structure operatively attached to at least one of said surfaces. It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention. BRIEF DESCRIPTION OF THE DRAWINGS The invention is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice and for the sake of clarity, the various features of the drawings are not drawn to scale. On the contrary, the dimensions of the various features may have been arbitrarily expanded or reduced. Included in the drawings are the following figures: FIG. 1 is an end view of a wall unit form showing mounting of a pair of hinged or removable side panels and an end panel according to a preferred embodiment of the present invention; FIG. 2 is a plan view of the wall unit form of FIG. 1 according to a preferred embodiment of the present invention; FIGS. 3A, 3 B, and 3 C depict front, side and top views, respectively, of a wall unit produced according to a preferred embodiment of the present invention; FIG. 4 depicts a perspective view of a double stone-face wall unit produced according to a preferred embodiment of the present invention; FIG. 5 depicts a detail plan view of the seamless joint between two wall units according to FIG. 4; FIG. 6 depicts a plan view of a double corner end unit according to one possible embodiment of the present invention; FIG. 7 depicts a plan view of a left or right corner end unit with an integral pocket formed therein according to one possible embodiment of the present invention; FIG. 8 depicts a plan view of a left or right end unit according to one possible embodiment of the present invention; FIG. 9 depicts a plan view of a double corner end unit with nonlinear and tapered surfaces according to one possible embodiment of the present invention; and FIG. 10 depicts a perspective view of a wall unit form with extensions in place to form a base or footing according to one possible embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention generally provides a method for forming wall units, and in particular to a method for constructing a wall unit having layered discrete veneer components on the outer surface of at least one side. The present invention further discloses the wall unit form which is utilized in the novel production method disclosed herein. The term “stone” veneer is used throughout the description of the invention solely for ease of communication. There is no intent to limit the veneer material to stone. Rather, any discrete building component may be employed in the method described herein. While this invention is susceptible to embodiment in many different forms, there is shown in the drawings, and will be described in detail, a preferred embodiment of the invention. It should be understood, however, that the present disclosure is to be considered as an exemplification of the principles of this invention and is not intended to limit the invention to the embodiment illustrated. 1. The Wall Unit Form Referring to FIG. 1, this figure shows an end view of a wall unit form 10 with first and second side panels 12 , 14 and a first end panel 16 . All of these panels, and second end panel 18 (FIG. 2 ), are mounted to each other upon the ground or upon a base panel 20 , according to the present invention. The side panels 12 , 14 , as well as the first and second end panels 16 , 18 can be hinged (as shown) or removably attached. An advantage of the movable panels 12 , 14 , 16 , 18 is that they facilitate entry into the wall unit form 10 during various production operations as will be discussed in the Method section below. The wall unit form 10 may also include a cavity to accommodate material that will form a base or footing if the footing is to be molded as an integral piece of the wall unit 50 . The base or footing cavity can be formed by extensions 84 that are attached, as necessary, to movable panels 12 , 14 , 16 , 18 (FIG. 10 ). The extensions 84 may be of any required contour, and these are capable of producing a base having either squared or radiused corners and ends. The wall unit form 10 is also adaptable to receive a form liner. The form liner is operationally attached to the interior of panels 12 , 14 , 16 , 18 and facilitates the desired alignment of irregularly-shaped veneer components, in a random horizontal and vertical orientation, against the form liner. The form-liner is a smooth sheet of material such as, inter alia, wood, metal, plastic, or the like, which covers and protects the interior surface of panels 12 , 14 , 16 , or 18 , and which can be used to reduce the overall size of a finished wall unit. Thus, a single wall unit form 10 , can be combined with a variety of different size form liners, to produce different size wall units. A form liner, as herein described, is thus distinguished from the “guide form” known in the related art (See, for example, U.S. Pat. No. 1,809,504 to Carvel, FIG. 18, element 24; and FIG. 26, element 32). The guide forms of the related art are affixed to the insides of the form panels to provide regular intervals between discrete components. The base panel 20 is further adapted to receive a pocket forming structure such as a footing loop pocket structure 24 . Use of the footing loop pocket structure 24 enables formation of a shear key or footing loop pocket 48 (FIGS. 3A, 3 B) in the bottom surface of the wall unit 50 . The connecting loop pocket structure 22 (FIG. 2 ), the footing loop pocket structure 24 (FIG. 1 ), and the lifting loop pocket structure 56 (FIG. 1) are structures that are temporarily and removably placed upon the panels 12 , 14 , 16 , 18 forming the wall unit form 10 to create longitudinal voids in the finished wall unit 50 . These voids are useful for accommodating means for interlocking adjacent wall units 50 as will be discussed herein below. The loop pocket structures (connecting, footing, and lifting, 22 , 24 , 56 , respectively) may be formed on any surface of the wall unit, but are typically formed on the ends, top, or bottom of the wall unit 50 . The loop pocket structures 22 , 24 , 56 are typically vee-shaped, but they may have any another cross-sectional shape which may be more suited to a particular application. Finally, the loop pocket structures 22 , 24 may be fabricated of metal, wood, plastic, or any other material having the structural properties required by this process. As shown in FIG. 2, the wall unit form 10 can receive a connecting loop pocket structure 22 at either or both ends. The connecting loop pocket structure 22 is attached to either or both end panels 16 , 18 . Use of the connecting loop pocket structure 22 allows a connecting loop pocket 46 (FIG. 3A) to be formed on the ends 52 , 54 of the wall unit 50 . Referring now to FIG. 3, there are shown several views of a wall unit 50 . FIG. 3A presents a front view of a wall unit 50 , showing a connecting loop pocket 46 at each end of the wall unit 50 . Connecting loop rods 30 extend into the connecting loop pockets 46 from the interior of the wall unit 50 . Similarly, lifting loop rods 28 extend into the lifting loop pocket 58 , and provide a means for lifting the wall unit 50 when so required. The connecting loop rods 30 and the lifting loop rods 28 are typically formed from reinforcing rods, commonly known as rebar, of sufficient size and quantity as dictated by the application. A footing loop pocket 48 is shown formed along the bottom of the wall unit 50 . Footing loop rods 70 may be formed that extend into the footing loop pocket 48 , in mirror image fashion compared to the lifting loop rods 28 and the lifting loop pocket 58 . The footing loop rods 70 may be used to anchor the wall unit to a concrete footing 36 or other base, typically by attachment to a footing-to-unit loop rod 64 (FIG. 4 ). Also shown is a chaseway 32 which can accommodate pipes, culverts, wiring, drainage, unit lifting means, windows, doorways, or the like. The chaseway 32 may be placed at other locations within the wall unit 50 . While only a single chaseway 32 is shown, a plurality of chaseways 32 may be employed as necessary. FIG. 3B shows a side view of a wall unit 50 presenting a second view of many of the features described above. Also shown here are a plurality of the stone veneer pieces 26 . The veneer pieces 26 comprise the sides of the wall unit 50 , while the inner space between the veneers is occupied by a binding or cementation material 34 . The binding or cementation material 34 may be cement, concrete, mortar, or other suitably binding material such as certain foams and plastic compounds. FIG. 3C depicts a plan view of the wall unit 50 , which further presents the features discussed above. The wall units 50 are not limited to having a stone veneer 26 on one or two sides. They may have a stone veneer 26 on any number of sides. For instance, FIG. 6 shows a double corner end unit 72 which has a rectangular shape, and a stone veneer covering four sides. A left or right end unit 76 may also be formed (FIG. 8 ). Further, the connecting loop pocket 46 need not be placed at an end of the wall unit 50 . It may be placed on a side to yield the left or right corner end unit 74 shown in FIG. 7 . Finally, the wall unit form 10 is not limited to a rectangular shape. The sides may be angled or curved to meet any design criteria. FIG. 9 depicts a composite wall unit 78 which includes both of these features. 2. Method of Making the Wall Unit The wall unit 50 is produced using the wall unit form 10 illustrated in FIGS. 1 and 2. As a first step, hinged or removable first and second surfaces or side panels 12 , 14 are removably attached to first and second end surfaces or panels 16 , 18 . The panels 12 , 14 , 16 , and 18 may also be affixed to an optional surface base or panel 20 at this time. However, depending on the size and configuration of the wall unit 50 that is to be constructed, either end panel 16 , 18 may be left off to facilitate access to the interior of the wall unit form 10 . The wall unit form 10 may commonly have a rectangular shape, but could have any desired shape, including angled sides, curved sides, or sloped sides (FIG. 9 ). Once the desired panels are in place, removable structures may be affixed to the panels. These structures function as connecting loop pocket structures 22 , footing loop pocket structures 24 , or lifting loop pocket structures 56 , depending on their placement within the form. Next, individual stones are placed along the bottom of at least one side panel. Successive layers of stones are stacked upon the initial layer, thereby forming a stone veneer 26 . Smaller pieces of stone or non-stone material may be used as shims 82 (FIG. 3B) to ensure a specified gap or joint size between the stones. Alternatively, the stones may be stacked with no spaces between them. The stone veneer can also be built to accommodate chaseways, drainage pipes, culverts, windows, doorways, lighting fixtures, etc., as required. A stone veneer may be built against a single wall, or preferably, on more than one wall at the same time. For those units requiring that there be no visible seams between wall units 50 , removable indentation blocks 80 (FIG. 4) are placed in appropriate locations in the stone veneer 26 . Once installation of the stone veneers 26 is completed, reinforcing rods are added as necessary to provide structural integrity, and to provide lifting loop rods 28 , connecting loop rods 30 , and footing loop rods 70 . Now that the discrete components of the wall unit 50 are in place, any panels 12 , 14 , 16 , and 18 which were not installed earlier are attached to complete the form. The wall unit form 10 is then filled with a binding or cementation material 34 . This binding material 34 is poured into the wall unit form 10 through the exposed upper area. The binding material 34 may be textured or colored, and may be a mortar, cement, concrete or similar mixture, or a plastic or foam compound. The binding material 34 is then allowed to cure. In some architectural applications it will be desirable for adjacent wall units 50 to appear as if there is no joint between them. In such cases, a temporary, removable indentation block 80 is placed at any suitable location in the stone veneer 26 array prior to addition of the binding material 34 . The indentation block 80 is removed after curing, thus leaving a void in the stone veneer 26 . A seamless joint can then be accomplished using a stone crossing joint 38 (FIG. 5) which is placed across the vertical joint between the units 50 utilizing the space vacated by the removable indentation block 80 (FIG. 4 ). Similarly, horizontal joints can be disguised between stacked wall units 50 . The wall unit 50 may also be formed with a footing or base 36 , wherein the footing 36 which is poured as an integral portion of the wall unit 50 at the same time that the remainder of the wall unit 50 is poured. The foregoing specification is intended as illustrative and is not intended to be taken as limiting. Still other variations within the spirit and scope of this invention are possible and will readily present themselves to those skilled in the art.

A method of forming a wall unit having a veneer face is disclosed. Initially, a pair of side wall panels and a pair of end panels are mounted substantially upright. Stones or other suitable material are set sequentially in a horizontally disposed course using at least one of the panels. Additional courses of stones or other material may then be stacked upon the initial layer until the desired height is attained. The interior volume of the apparatus is left substantially empty, and is then filled with a binding material. The binding material binds the courses' components together and integrates the individual courses into a single cohesive unit. The wall and end panels are removed and the unit is removed for subsequent installation.

BACKGROUND OF THE INVENTION 1. Field of Invention The present invention relates in general to a distributed temperature sensing method based on the spontaneous Brillouin scattering effect, more particular, to a spectrum decomposing method to achieve high spatial resolution, high temperature resolution and long sensing range of the distributed temperature measurement. 2. Description of Related Art There are two ways to fulfill the distributed sensing approach. One includes the use of single sensors being discretely arranged along a sensing line, but will make the whole sensing system much complicated. The other one as described hereinafter includes the use of optical-fiber sensors to obtain the detecting physical parameters along a linear fiber depending upon the optical characteristics thereof. Under the circumstances, the optical fiber are regarded, on one hand, as an active component for sensing measurement and, on the other hand, as a passive component for the information transmitting material to obtain the following advantages: 1. The optical fiber is small in volume and light. Thus, the optical fiber can be adopted easily anywhere. 2. Since the frequency bandwidth of the optical fiber is large, many signals may be transmitted simultaneously. 3. Since the optical fiber is made of nonconductive insulating material, it is not influenced by external electromagnetic waves. Thus, the signal may be transmitted without noise. 4. Due to the development of optical fiber technology, optical fibers can be manufactured at a low cost. As such, the utilization of fiber-distributed sensing for the measurement of strain and/or temperature distribution is widely applied on many implementations to monitor such as tunnels, bridges, dams and airplanes, buildings and etc. for safety-secured purpose. Recently, the distributed temperature sensors (DTS's) that use Brillouin scattering as the sensing mechanism have been intensive studied. The Brillouin frequency shift is dependent on the temperature and strain conditions of the optical fiber, which provides the basis for a sensing technique capable of detecting these two parameters. In the Brillouin-based distributed temperature sensing system, if a higher spatial resolution is accomplished, the measured temperature distribution is more closed to the practical situation of the fiber. The sensing spatial resolution is defined as the 10%/90% rise times from the unheated section to the heated section of the fiber. To achieve higher spatial resolution in a Brillouin scattering system, the measurements utilizing a short-pulsewidth laser source have been reported, which are disclosed by T. Horguchi, K. Shimizu, T. Kurashima, M. Taleda, and Y Koyamada, published in J. Lightwave Technol ., 13, 1296 (1995), and A. Fellay, L. Thevenaz, M. Facchlni, M. Nikles, and P. Robert, published in Proc. OSA Tech. Dig ., 16, 324 (1997). However, owing to the Brillouin linewidth limitation, it is obvious that using the time-domain pulsed approach is unsuitable for distributed measurements of submeter spatial resolution unless other techniques are employed. More recently, several methods have been reported for performing the measurement with submeter spatial resolution. One such technique, disclosed by K. Hotate and T. Hasegawa, published in Tech. Dig. Opt. Fiber Sens ., 17, 337(1999), is the direct-frequency modulation method that demonstrated a sensing spatial resolution of 45 cm over 7.8 m sensing range, and another techniques, disclosed by M. D. DeMerchant, A. W. Brown, X. Bao, and T. W. Bremner, published in J. Lightwave Technol . 38, 2755 (1999), and A. W. Brown, M. D. DeMerchant, X. Bao, and T. W. Bremner, published in J. Lightwave Technol . 17, 1179 (1999), utilize the sensing fiber with uniform strain and identical length in each section to achieve the spatial resolution of 40 cm and even 25 cm with the enhancement of compound spectra processing method. In addition, a Brillouin-based distributed temperature sensing system that provide a spatial resolution of 35 cm and a temperature resolution of 4.3° C. over 1 km based on measuring the Landau-Placzek ratio with a pulsewidth of 3.5-ns has also been reported by H. H. Kee, G. P. Lees, and T. P. Newson, IEEE Photon, Technol. Lett ., 12, 873 (2000). However, the short-pulsewidth laser sources are requisite for these methods to accomplish measurements of submeter spatial resolution. Thus the sensing ranges of these methods are limited. SUMMARY OF THE INVENTION It is therefore, in one aspect, an object of the present invention to provide a method that can provide a distributed temperature measurement with high spatial resolution and long sensing range based on decomposing the spectra of the spontaneous Brillouin scattered signals. This method utilizes a long-pulsewidth laser source to derive the long sensing range and employs a signal processing technique of decomposing Brillouin spectrum to raise the spatial and resolutions to submeter level. According to the above-mentioned objects of the present invention, the method for distributed temperature measurement based on decomposing spectra of spontaneous Brillouin scattered signals includes: (a) supplying a laser source with an optical pulse to an optical fiber; (b) obtaining a first measured Brillouin spectrum in a reference temperature section of the optical fiber, and at least a second measured Brillouin spectrum and a third measured Brillouin spectrum in a temperature overlapped region of the optical fiber, the measured Brillouin spectra above corresponding to the optical pulse entering a fiber section of the optical fiber with a length of d at a traveling time t d for t i >t d >t 0 and a sampling interval t 1 −t 0 ; (c) determining the length of d according to the measured Brillouin spectra above and a weighting factor ranging from 0 to 1; (d) determining a real Brillouin spectrum profile of the fiber section according to the length of d, the corresponding weighting factor and the measured Brillouin spectra above; and (e) determining a temperature distribution according to Brillouin frequency shifts of the real Brillouin spectrum profile. As a result, a spontaneous Brillouin-based distributed temperature sensing system using a new Brillouin spectrum decomposing technique to achieve high spatial and position resolutions, high temperature resolution and long sensing range. For a 9500-m sensing range of standard single-mode fiber and a 100-ns pulsewidth laser source, a spatial resolution of 20 cm and a temperature resolution of 1° C. are simultaneously achieved by using this signal processing method. Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become fully understood from the detailed description given herein below illustration only, and thus are not limitative of the present invention, and wherein: FIG. 1 ( a ) shows an experimental setup for a long-range sensing approach according to the present invention. FIG. 1 ( b ) shows an experimental setup for a short-range sensing approach according to the present invention. FIG. 2 shows the averaged change in Brillouin frequency shift as a function of temperature change by comparison structure in FIG. 1 ( a ). FIG. 3 shows the measured optical pulse shape and the corresponding weighting factor versus the overlap time of the optical pulse and the sensing fiber. FIG. 4 shows the positions of sensing fiber obtained by the present invention with respect to the ideal one versus the changes. FIG. 5 shows the measured and calculated results of the change in Brillouin frequency shift and the corresponding temperature along the fiber in FIG. 1 ( a ). FIG. 6 shows the measured and calculated results of the change in Brillouin frequency shift and the corresponding temperature along the fiber in FIG. 1 ( b ). DETAILED DESCRIPTION OF THE INVENTION According to the paper discloses by T. Kurashima, M. Taleda, T. Horguchi, and Y Koyamada, published in IEEE Photon, Technol. Lett ., 9, 360 (1997), the Brillouin optical-time-domain reflectormeter (BOTDR) can be used to measure the spontaneous Brillouin spectra along an optical fiber from one-end. If the temperature in a fiber section is not uniform, a compound Brilloum spectrum composed of the frequency-domain signals of two sections is observed in the overlapped area where the traveling optical pulse is crossing these two sections. Assuming that an optical pulse enters a fiber section with a length of d at the traveling time t d and the measured Brillouin spectra, A(t i ) are known for t i >t d >t 0 (t 0 =t 1 —sampling interval), the real Brillouin spectrum in this fiber section can be derived by decomposing the measured Brillouin spectra. The subscript, i, represents the sampling sequence of the returned Brillouin scattering Iightwave within this fiber section. If the real Brillouin spectrum profile of this fiber section is B, then the relationship between B and A(t 1 ) can be expressed by A ( t 0 )·(1 −W ( t i −t d ))+ B ·( W ( t i −t d ))= A ( t i ) for t i −t d <d /( c/n ),  (1) A ( t 0 )·(1 −W ( t i −t d )+ W ( t i −t d −d·n/c ))+ B ·( W ( t i −t d )− W ( t i −t d −d·n/c ))= A ( t i ) for d/(c/n)≦t i −t d ≦pulsewidth,  (2) where c is the velocity of light in a vacuum, n is refraction of index, and W(t i −t d ), ranged from 0 to 1, is a weighting factor determined by the optical pulse shape and overlap time. Thus t d , d and B can be derived from the above equations by substituting the measured profiles of compound Brillouin spectra in the overlap area. Moreover, the corresponding sensing temperature of this fiber section will be obtained from the change in the Brillouin frequency shift of B. For Example, if the temporal sampling interval of BOTDR is short enough to achieve t 2 −t d <d/(c/n), then t d according to Eq. (1), obtained implicitly by A  ( t 0 ) · [ 1 - W  ( t 2 - t d ) + W  ( t 2 - t d ) · ( 1 - W  ( t 1 - t d ) ) W  ( t 1 - t d ) + A  ( t 1 ) · W  ( t 2 - t d ) W  ( t 1 - t d ) - A  ( t 2 ) = 0 ( 3 ) In addition, Brillouin spectrum profile, B, can be given by B = A  ( t 1 ) - A  ( t 0 ) · ( 1 - W  ( t 1 - t d ) ) W  ( t 1 - t d ) ( 4 ) Consequently, the sensing temperature of this fiber section is derived from the Bnulouin frequency shift of B. Nevertheless, the sensing spatial resolution that is defined as the 10%/90% rise times from the unheated section to the heated section is independent of the used optical pulsewidth of BOTDR. As a result, a distributed temperature measurement with a high spatial resolution and a long sensing range can be accomplished by using a short sampling interval and a long-pulsewidth laser source based on this signal processing method of decomposing Brillouin spectra. FIG. 1 shows the experimental setup. A BOTDR with operating wavelength at 1554-nm is used to measure the spontaneous Brillouin spectra along the length of standard single-mode fiber (SMF). For the temperature measurement, three separate sections of the test SMF and an optical switch box are arranged as shown in FIG. 1 ( a ). The optical switch box, as shown in FIG. 1 ( a ), was composed of a pair of 1×5 optical switches and five fiber paths with lengths of 1.20, 1.72, 2.18, 2.71, and 3.18, respectively. The first 9.473-km SMF remained on the original spool as supplied by the manufacturer, the subsequent 20-m SMF is subject to a low-level tension as a reference section, and the final sensing 50-m SMF is placed in a thermally insulated oven. The operating conditions of BOTDR are as following: output power of 23 dBm, pulsewidth of 100 ns, average times of 2 15 , sweep frequency of 5 MHz, and sampling interval of 2m. FIG. 2 is a plot of the averaged change Δν B in Brillouin frequency shift as a function of temperature change (ΔT) by comparing the Brillouin frequency shift of the 50-m sensing SMF with that of the 20-m reference fiber. From these data, the temperature coefficient of the Brillouin frequency shift is determined to be 0.934 MHz/° C. for this SMF. In addition, it can be observed that the temperature resolution is less than 1° C. by using this 50-m sensing SMF. FIG. 3 shows the measured optical pulse shape under the BOTDR condition of 100-ns pulsewidth and the corresponding weighting factor, W(t i −t d ), versus the overlap time, (t i −t d ), of the optical pulse and the sensing fiber. It is obvious that the optical pulse has a rise/fall time of <5-ns and the weighting factor is presenting a linear relationship to the overlap time when the overlap time is not in the rising and falling region. To verify that the submeter position and spatial resolutions can be achieved for the temperature measurement by using this signal processing method, the condition in this experiment setup was as same as that in the above case of FIG. 1 ( a ) except that the BOTDR parameter of 1-m sampling interval is set. By switching the 1×5 optical switch pair, the changes in the position of 50-m sensing fiber with 50-cm step can be obtained. In addition, the temperature in the oven was set as 45° C. and the room temperature for reference was 22° C. Using the arrangement in FIG. 1 ( a ), the Brillouin spectra in the overlap region of reference fiber and sensing fiber are measured for different fiber paths in the optical switch box; thus, the location of 50-m sensing fiber for each case can be derived by substituting the measured results into Eq. (3). FIG. 4 shows the positions of the 50-m sensing fiber that are derived by using this Brillouin spectrum decomposing method versus the changes, ΔL, in the position of 50-m sensing fiber referred to the 1.20 m fiber path. Also from FIG. 4, it is known that the position error is within ±10 cm. To further confirm that the submeter spatial resolution is achievable, the oven temperature of 45.2 or 47.3° C. and the temperature of24° C. in reference fiber section were set. In addition, the optical switch box is removed. FIG. 5 shows the measured and calculated results of the change Brillouin frequency shift and the corresponding temperature along the fiber. The 10%/90% rise times (also defined as the spatial resolution) from the unheated section to the heated section are measured as 8 m and 8.5 m for oven temperature at 45.2 and 47.3° C., respectively. However, they can be dramatically improved to 20 cm and the corresponding temperature error are within ±0.5° C. as shown in the calculated curves. As a result, a distributed temperature measurement with 20-cm position and spatial resolutions, 1° C. temperature resolution and 9500-m sensing range can be accomplished by using this Brillouin-spectrum decomposing method under the condition of 100-ns pulsewidth laser source. To demonstrate the feasibility of this method for the sensing fiber shorter than the product of (c/n) times the optical pulsewidth, the sensing fiber of 1-m is used as shown in FIG. 1 ( b ). In the experimental setup of FIG. 1 ( b ), four separate sections of the test SMF are arranged. Moreover, these four SMF sections are the first 9.473-km SMF remained on the original spool, the subsequent 28-m SMF with low-level tension, the sensing 1-m SMF in the oven, and the final 20-m SMF with low-level tension. The BOTDR parameters are consistent with those in the above experiment. Using this signal processing method, FIG. 6 shows the measured results of the change in Brillouin frequency shift and the corresponding calculated results of temperature along the fiber for oven temperatures at 45.1 and 47.1° C. and reference fiber section at 20° C. for 1-m sensing fiber. After substituting the measured results into Eq. (3) and (4), the positions (t d ) of the 1-m sensing fiber are calculated as 9501.7 and 9501.6 m for over temperatures at 45.1 and 47.1° C., respectively. In addition, the sensing fiber lengths (d) are derived as 1.1 m for over temperature 45.1 and 47.1° C. Also from these calculations, the sensing temperature for oven temperature at 45.1 and 47.1° C. are 45.0 and 47.2° C., respectively. Consequently, the temperature measurement with spatial resolution of 20-m, temperature resolution of 1° C. and sensing range of 9500 m is retrieved by using this Brillouin-spectrum decomposing method under the condition of 100-ns pulsewidth laser source. The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

A method that utilizes a short sampling interval and a long-pulsewidth laser source to obtain the long sensing range and employs a signal processing technique of decomposing Brillouin spectrum to achieve high spatial resolution, high temperature resolution of the distributed temperature measurement is disclosed. The present method includes the steps of measuring the Brillouin spectra of an optical pulse applying to a sensing fiber and a overlapped area thereof, determining the length that the pulse enters according to the measured Brillouin spectra and a weighting factor and then determining a real Brillouin spectrum profile and a temperature distribution according to Brillouin frequency shifts thereof. For a 9500-m sensing range of standard single-mode fiber and a 100-ns pulsewidth laser source, spatial and positon resolutions of 20 cm and a temperature resolution of 1° C. are simultaneously achieved by using this signal processing method.

This application is a continuation application under 37 C.F.R. §1.53(b) of prior application Ser. No. 08/771,808 filed Dec. 23, 1996, now U.S. Pat. No. 5,827,439. The disclosures of the specification, drawings and abstract of application Ser. No, 08/771,808 are incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to a liquid quenching method for manufacturing an amorphous metal wire or thin strip (hereinafter "thin strip") by quenching and solidifying a molten alloy on a moving cooling substrate. More particularly, the present invention relates to a method for supplying molten alloy from a ladle storing the molten alloy to a tundish. 2. Description of the Prior Art Liquid quenching methods for producing thin strips include, for example, the single roll method which discharges a molten alloy on to a single cooling roll rotating at a high speed resulting in the manufacture of a thin strip. In the twin roll method, the molten alloy is discharged between a pair of cooling rolls rotating at a high speed resulting in the manufacture of a thin strip. A liquid quenching method which uses a single roll cooling/solidification apparatus, as shown in FIG. 7, will be explained. Molten alloy 6 is poured into a tundish 5 so that the level of the molten metal becomes constant. Twyer bricks 9 are disposed on the bottom wall of this tundish 5. An intermediate nozzle 10 and a nozzle holder 11 are interconnected to a passage 13 bored in these twyer bricks 9 to provide a fluid path for the molten alloy. An expanded internal space 14 is located inside the nozzle holder 11. A nozzle chip 12 is fitted to the distal end of the nozzle holder 11, and a nozzle slit 15 is inserted inside this nozzle chip 12 for discharging molten alloy onto the chill roll 8. The expanded internal space 14 inside the nozzle holder 11, the nozzle chip 12 and the nozzle slit 15 are illustrated in FIG. 8. Here, the expanded internal space 14 represents an expanded portion of the molten metal passage 13 inside the nozzle holder 11 so as to obtain a thin strip having a large width. The nozzle slit 15 provides an opening for jetting the molten metal flowing through the nozzle chip 12. When a tundish stopper 4 is moved up, the molten alloy 6 inside the tundish 5 is allowed to flow through the molten metal passage 13 and is jetted from the nozzle slit 15 onto the cooling roll 8. At this time, the flow rate of the molten alloy 6 flowing out from the nozzle slit 15 onto the cooling roll 8 is controlled in accordance with the static pressure of the molten metal inside the tundish 5. The molten alloy 6 jetting out from the nozzle slit 15 is rapidly cooled on the surface of the cooling roll 8 and is formed into the thin strip 7. The cooling roll 8 is illustrated in a small scale compared with the large scale of the tundish 5 in FIG. 7 in order to make the entire apparatus more easily understood. In order to obtain the thin strip by either of the liquid quenching methods described above, the cooling rate must be set to at least about 10 2 K/sec. Therefore, there is a limitation on the sheet thickness of the resulting thin strip. It is as small as less than about 0.1 mm. When the thin strips having a thickness of less than 0.1 mm are produced by the liquid quenching method, there are differences in the limiting conditions of the various production factors in comparison with ordinary ingot casting methods and continuous casting methods according to conventional solidification technologies. The most important limiting condition is the feed quantity of the molten alloy. In the case of the continuous casting methods for steels, etc, that have been ordinarily employed, the quantity of the molten alloy that can be provided to a casting mold is several tons per minute. A greater quantity of molten alloy can be provided in ordinary ingot casting methods. In contrast, in the liquid quenching method which is the subject of the present invention, the feed quantity of the molten alloy must be reduced to a very small quantity of not greater than 100 kg/min. This is because of the limitation on the thickness of the thin strip. The maximum strip thickness that can be ordinarily obtained by the single roll method, for example, is about 0.1 mm. The peripheral speed of the cooling roll in this case is about 10 m/sec and the maximum width of the thin strip is about 200 mm. In the case of alloys containing iron as the principal component, the feed quantity of the molten alloy must be controlled to about 90 kg/min. When the thin strip is produced by the liquid quenching method in an industrial practice, it is a very important to minimize the feed quantity of the molten alloy. In the case of a conventional continuous casting method, for example, the molten alloy is supplied from a ladle to the casting mold through a tundish. In this instance, a system using a ladle stopper fitted to a long nozzle hole at the bottom of the ladle is employed as one of the methods of controlling the feed quantity of the molten alloy. In other words, the feed quantity of the molten alloy is controlled by moving the ladle stopper up and down, thereby controlling an opening area of the long nozzle. Since a conventional continuous casting method can supply a large quantity of the molten alloy such as several tons per minute as described above, the feed quantity can be easily controlled by such a stopper system. In contrast, in the case of the liquid quenching method, which is the object of the present invention, the feed quantity of the molten metal must be limited to not greater than 100 kg/min. Therefore, it becomes difficult to employ, as such, the stopper system described above. Japanese Unexamined Patent Publication (Kokai) No. 1-34550, for example, proposes a method which uses the stopper system in the liquid quenching method. Though this method is not limited to the production of the amorphous alloy thin strip, it is devised so as to reduce the relative feed quantity of the molten alloy. It measures the weight of the molten alloy inside the tundish during charging and controls the up or down moving speed of the ladle stopper and the ladle stopper position on the basis of this measurement so as to control the feed quantity of the molten alloy. This method limits the lower limit of the moving distance of the ladle stopper to 2 mm and the upper limit to 6 mm. It can control the feed quantity of the molten alloy with a very high level of accuracy. According to this method, however, the weight of the tundish must be measured during charging and hence, the control becomes complicated. Further, because a measuring instrument and a computer must be installed, the setup cost becomes high and thus the production cost becomes high. If the moving distance of the ladle stopper is limited to an excessively small value, the operation becomes more difficult because most installations are not free from vibrations no matter how precise they may be. Because of vibration problems, the moving distance of the ladle stopper must be at least about 5 mm. SUMMARY OF THE INVENTION It is an object of the present invention to provide a simple and economical method for supplying a molten alloy for producing a thin strip which solves the problems encountered in the feed control of the molten metal in the conventional liquid quenching method by specifying the correlation between a long nozzle and a stopper. The gist of the present invention resides in the following points. The present invention is directed to method for supplying molten alloy to a moving cooling substrate for producing an amorphous metal wire or an amorphous metal thin strip. A ladle is provided for receiving the molten alloy, with the ladle having a bottom wall defining a bottom surface of the ladle. A long nozzle is provided having a length and having an interior passage therein extending the length of the long nozzle. The length of the interior passage extends in a perpendicular direction or inclined to the perpendicular direction. The long nozzle has one end connected to the bottom wall of the ladle placing the interior passage of the long nozzle in fluid communication with the molten alloy in the ladle. A ladle stopper is provided disposed within the ladle. The ladle stopper has an outer wall surface parallel to the perpendicular direction. A tundish is provided below the ladle and in fluid communication with the long nozzle for receiving molten alloy from a distal end of the interior passage of the long nozzle. Molten alloy is supplied from the ladle to the tundish by feeding molten alloy via the interior passage of the long nozzle. Molten alloy is supplied from the tundish to the moving cooling substrate. The ladle stopper is provided with a distal end region having a length which is received by the interior passage of the long nozzle at the one end of the long nozzle. A distance (y) is defined as an overlap distance of the length of the distal end region of the ladle stopper received by the interior passage of the long nozzle during flow of the molten alloy through the interior passage. An opening area (Ao) is defined which is a sectional area for molten alloy flow provided by the opening area in the interior passage of the long nozzle resulting from receiving the distal end region of the ladle stopper. A distance (Ln) is defined as the distance from the bottom surface of the ladle to the minimum cross-sectional area of the interior passage of the long nozzle. A distance (Lm) is defined as the distance from the bottom surface of the ladle to a height of molten alloy in the ladle at start of feed of the molten alloy. When (y) is less than 0.1 mm, Ao is set to be 1.2 cm 2 and a ratio (Ln)/(Lm) is set be at least 1.5. When (y) is 0.1 to 200 mm, Ao is set to be 0.5 to 10cm 2 . In another embodiment of the present invention, feed of molten alloy is started from the ladle to the tundish by moving the ladle stopper upward a selected distance thereby placing the ladle stopper in a selected position. The ladle stopper is maintained in the selected position until feeding of the molten alloy is completed. In a further embodiment of the present invention, the distal end region of the ladle stopper is a protrusion having a length of at least 5 mm and having an outer wall surface, with the outer wall surface of the protrusion being parallel to the perpendicular direction. The interior passage of the long nozzle has an inner wall surface. The outer wall surface of the protrusion does not contact the inner wall surface of the interior passage when the protrusion is received by the interior passage. In still a further embodiment of the present invention, the distal end region of the ladle stopper is a protrusion having a length of at least 5 mm and having an outer wall surface, with the outer wall surface of the protrusion being parallel to the perpendicular direction. The interior passage of the long nozzle has an inner wall surface. A portion of the outer wall surface of the protrusion contacts the inner wall surface of the interior passage when the protrusion is received by the interior passage. In yet another embodiment of the present invention, the interior passage of the long nozzle has an inner wall surface and at least one obstacle to molten alloy flow is disposed on the inner wall surface of the interior passage. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an apparatus used for practicing the method of the present invention. FIGS. 2(a) to 2(c) are views showing an example of a ladle stopper equipped with a protrusion that is used in the method of the present invention. FIG. 3 is a schematic view showing an example of a ladle stopper and a long nozzle used in the method of the present invention. FIG. 4(a) is a schematic view and FIG. 4(b) is an enlarged schematic view showing an example of a ladle stopper equipped with a protrusion and a long nozzle used in the method of the present invention. FIGS. 5(a), 5(c) and 5(d) are sectional views taken along a line I--I of FIG. 3 and a line II--II of FIG. 4(a) showing the relationship of an overlap portion between a ladle stopper and a long nozzle used in the method of the present invention, wherein (a) and (b) show a noncontact state and (c) and (d) show a contact state, respectively. FIGS. 6(a), 6(b), 6(c), 6(d) and 6(e) are views showing an example where an obstacle is disposed inside a long nozzle used in the method of the present invention. FIG. 7 is a schematic view useful for explaining a single roll quenching/solidification apparatus used to cast a thin strip. FIG. 8 is an enlarged schematic view useful for explaining a casting state using a single roll quenching/solidification strip production apparatus. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail with reference to the accompanying drawings. FIG. 1 is a schematic view showing an apparatus for the production of thin strip amorphous metal used for practicing the method of the present invention. A molten alloy held inside a ladle 3 is supplied to a tundish 5 by raising a ladle stopper 1 through a long nozzle 2. Next, the molten alloy is ejected at a high speed from a nozzle 7 and impinged onto a cooling roll 8 rotating at a high speed so as to form an amorphous thin strip 7. The flow of molten alloy is controlled by an opening/closing operation of tundish stopper 4 disposed inside the tundish. The inventors of the present invention conducted intensive studies on methods of uniformly and stably supplying a molten alloy at a rate below 100 kg/min. The present inventors discovered that the feed quantity of the molten alloy depends on the length of an overlap portion between the distal end of the ladle stopper and the long nozzle. The present inventors also discovered that the feed quantity of the molten alloy depended upon the shape of the distal end of the ladle stopper and upon the area of opening defined between the ladle stopper and the long nozzle. The resistance at the time of passage of the molten alloy can be changed by using a stopper having a thin protrusion of a length of 5 mm at the distal end portion thereof as the ladle stopper. An overlap portion is provided in the horizontal direction between the distal end of the ladle stopper and the long nozzle and this overlap portion is changed. By this method, the feed quantity of the molten alloy can be controlled. If the protrusion at the distal end of the ladle stopper is elongated, the overlap portion can be set to a predetermined length even when the moving distance of the ladle stopper is large. As a consequence, even when the moving distance of the ladle stopper is increased to at least 5 mm, the feed quantity of the molten alloy can be stably reduced to a rate not greater than 100 kg/min by combining and controlling the overlap portion and the opening area (Ao) defined by this overlap portion. When the length of this overlap portion is small, however, setting of the opening area (Ao) can be controlled in the following manner. In such a case, the set position of the opening area (Ao) may be shifted below the long nozzle. It is necessary in this case, however, to change the set position of the opening area (Ao) in such a manner as to correspond to the height of the molten metal surface inside the ladle at the start of the feed of the molten alloy. The feed quantity of the molten alloy can be supplied stably and uniformly at a rate of not greater than 100 kg/min by conducting casting so that: (1) The opening area (Ao) inside the long nozzle is not greater than 1.2 cm 2 and the ratio (Ln/Lm) of the distance (Ln) from the bottom surface of the ladle to the position of the minimum sectional area inside the long nozzle to the height (Lm) of the molten metal level inside the ladle from the bottom surface of the ladle at the start of the feed of the molten alloy is at least 1.5 when the distance (y) of the overlap portion between the distal end portion of the ladle stopper and long nozzle is less than 0.1 mm. (2) The opening area (Ao) inside the long nozzle is 0.5 to 10 cm 2 when the distance (y) is from 0.1 to 200 mm. The stopper 1 used in the present invention is equipped with the protrusion 1A at the distal end thereof. This protrusion 1A has a shape corresponding to the intended production condition thin strip. The protrusion may have a small elliptic shape or a rectangular shape as shown in FIGS. 2(a) to 2(c), by way of example. When the protrusion is rectangular, the outer wall surface of this protrusion is preferably in parallel to the perpendicular direction. The example where the protrusion 1A is small and elliptic corresponds to case (1) described above. Since in this instance it is difficult to stably set the opening area (Ao) defined by the overlap portion between the distal end of the ladle stopper and the long nozzle to a predetermined value, the opening area (Ao) inside the long nozzle must be set to a value not greater than 1.2 cm 2 when the distance (y) of the overlap portion between the distal end of the ladle stopper and the long nozzle is less than 0.1 mm. The ratio (Ln/Lm) of the distance (Ln) from the ladle bottom surface to the minimum sectional area position inside the long nozzle to the height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten metal must be set to at least 1.5. On the other hand, when the protrusion 1A has a rectangular shape and when the distance (y) of the overlap portion between the distal end portion of the ladle stopper and the long nozzle is from 0.1 to 200 mm, the opening area (Ao) inside the long nozzle must be set to 0.5 cm 2 to 10 cm 2 . The inventors of the present invention have carried out experiments and studies by using stoppers having the conventional shapes such as those shown in FIGS. 2(a) and 2(b) in order to clarify the relationship between the long nozzle opening area and the flow rate of the molten alloy in the conventional method which reduces the flow rate of the molten alloy by reducing the area of the nozzle opening portion at the distal end of this stopper. Fe--B--Si--C system amorphous alloys were primarily used for this experiment. As a result, it has been discovered that in order to set the flow rate of the molten alloy to a value not greater than 100 kg/min by the conventional method, it is necessary to set the opening area (Ao) of the long nozzle to not greater than 1.2 cm 2 , the distance (y) of the overlap portion between the distal end of the stopper and the long nozzle to less than 0.1 mm and the ratio (Ln/Lm) of the distance (Ln) from the ladle bottom surface to the minimum sectional area position inside the long nozzle to the height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten alloy to at least 1.5, as shown in FIG. 3. It has been further discovered that once the ladle stopper 1 is elevated by a predetermined distance at the start of the feed of the molten alloy, the stopper 1 must be kept at that position until the feed of the molten alloy 6 is completed. It had been believed in the past that the molten metal generates so-called "nozzle clogging" at such a small sectional area. Therefore, the result described above is quite opposite to the common belief. Here, the term "opening area inside the long nozzle" means the minimum value of the sectional area of the long nozzle inner surface in the horizontal direction. In the case of the long nozzle which is conical and whose sectional area in the horizontal direction decreases in the flowing direction of the molten metal 6 as shown in FIG. 3, for example, the term indicates the inner area (Ao in FIG. 3) of the lowermost portion of the long nozzle 2. The terms "distance (Ln) from the ladle bottom surface to the minimum sectional area position inside the long nozzle" and "height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten alloy" will be explained. First, the term "distance (Ln) from the ladle bottom surface to the minimum sectional area position inside the long nozzle" means the distance (Ln in FIG. 3) in the vertical direction from the bottom portion of the ladle 3 to the lowermost portion of the long nozzle 2 representing the minimum sectional area inside the long nozzle. The term "height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten alloy" means the initial height (Lm in FIG. 3) of the molten alloy 6 held in the ladle 3. The sectional area of the long nozzle shown in FIG. 3 in the horizontal direction progressively decreases in the lower direction. Therefore, the minimum sectional area inside the long nozzle exists at the lowermost portion of the long nozzle. When the distance (y) of the overlap portion between the long nozzle and the distal end portion of the stopper is less than 0.1 mm in the long nozzle used in the present invention, the position of the opening area may be at any position inside the long nozzle if the opening area inside the long nozzle is not greater than 1.2 cm 2 . FIG. 3 shows two positions as the stop positions of the ladle stopper. That is, the position before the feed of the molten alloy 6 to the tundish is started and the position at which the molten alloy 6 is being fed. In other words, the solid line represents the former position and the dotted line, the latter position. In the present invention, the ladle stopper 1 is kept fixed at the position indicated by the dotted line while the molten alloy 6 is being fed from the ladle 3 to the tundish. The method of the present invention can keep the feed quantity of the molten alloy constant even when the ladle stopper position is fixed during the feed of the molten alloy. The reason why the feed quantity of the molten alloy can be kept constant even when the ladle stopper is fixed will be described later. Because the position of the ladle stopper can be thus fixed during the feed of the molten alloy, it is no longer necessary to measure the weight of the tundish and to control the feed quantity of the molten alloy by moving the ladle stopper position up and down as has been required in the prior art. Therefore, the molten alloy can be fed easily and economically. Incidentally, the moving distance of the ladle stopper (Ls in FIG. 3) at the start of the feed of the molten alloy is not particularly limited, but a small value is not preferred in consideration of the vibration of the apparatus. The moving distance is preferably from about 5 to about 50 mm. The inventors of the present invention have also discovered that when the ratio (Ln/Lm) of the distance (Ln) from the ladle bottom surface to the minimum opening area position inside the long nozzle to the height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten alloy is set to at least 1.5, thickness fluctuations in the resulting thin strip do not occur. In other words, when the feed quantity of the molten metal changes, the height of the molten metal level of the molten alloy in the tundish changes, and this change of the molten metal level in the tundish directly results in the fluctuation of the jet pressure of the molten alloy impinged onto the cooling roll. Eventually, the fluctuations occur in the sheet thickness of the resulting thin strip. Therefore, the feed quantity of the molten alloy supplied from the ladle must be made as uniform as possible. However, when the ratio (Ln/Lm) of the distance (Ln) from the ladle bottom surface to the minimum sectional area position inside the long nozzle to the height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten alloy is set to at least 1.5, the fluctuations of the strip thickness, which becomes a problem in the resulting thin strip, cannot be observed. This is the reason why the present invention sets the ratio (Ln/Lm) of the distance (Ln) from the ladle bottom surface to the minimum sectional area position inside the long nozzle to the height (Lm) of the molten metal level inside the ladle at the start of the feed of the molten alloy to at least 1.5. In other words, because the distance (Ln) from the ladle bottom surface to the minimum sectional area inside the long nozzle is set to be greater than the height (Lm) of the molten metal level inside the ladle, the influence of the height of the molten metal level inside the ladle, that affects the feed quantity of the molten alloy, becomes small. When the distance (Ln) from the ladle bottom surface to the minimum sectional area inside the long nozzle becomes at least 1.5 times the height (Lm) of the molten metal level inside the ladle, the influence of the height of the molten metal level inside the ladle that affects the feed quantity of the molten alloy presumably becomes zero. Therefore, in the present invention, no fluctuation occurs in the feed quantity of the molten alloy even when the feed quantity is not controlled by moving the ladle stopper up and down during the feeding operation of the molten alloy. In other words, the ladle stopper can be kept fixed from the start till the end of the feed of the molten alloy. The value of Ln/Lm is preferably somewhat greater that 1.5 provided that this is permitted by the installation space. If the production of the long nozzle having a minimum sectional area of not greater than 1.2 cm 2 is difficult, a long nozzle having a large sectional area is produced in advance as shown in FIGS. 6(a) to 6(e). Then an obstacle 16 having a varying shape is fitted into this long nozzle so that the resulting long nozzle has a reduced sectional area. The shape of the obstacle 16 include several different types. Examples are: at least one concentric circle obstacle, a spiral like obstacle, several protruded obstacles or porous like bricks. The sectional shape inside the long nozzle is not particularly limited in the present invention. In other words, so long as the minimum sectional area inside the long nozzle is not greater than 1.2 cm 2 , the sectional shape inside the long nozzle may be round, elliptic, polygonal or flowershaped. Further, the sectional shape inside the long nozzle may change in the flow direction of the molten alloy 6. According to the prior art, the moving distance of the stopper must be set to an extremely small value of not greater than 2 mm. The term "moving distance of the stopper" means the distance indicated by Ls in FIG. 3 and is the stroke distance (hereinafter called the "stopper stroke") at the time of opening of the stopper for feeding the molten alloy. Most setups are not free from vibration even though they may be of a precision type. In view of vibrations, it is extremely difficult to stably set the stopper stroke to not greater than 2 mm in practical operation. In view of vibrations, the stopper stroke is preferably at least about 5 mm. Therefore, the inventors of the present invention have examined feeding methods for molten alloys for setting the flow rate of the molten alloy to not greater than 100 kg/min even at a stopper stroke of at least 5 mm. The inventors found that when the long nozzle has a shape such that the inner wall surface of the opening at its upper portion is parallel to the perpendicular direction and the stopper has the protrusion at the distal end thereof whose outer wall surface is in parallel with the perpendicular direction as already described, the long nozzle opening area can be kept constant even when the stopper stroke is increased. When the y value shown in FIG. 4(a) is increased to a certain extent, the feed quantity of the molten alloy can be kept below 100 kg/min even when the long nozzle opening area exceeds 1.2 cm 2 . The stopper 1 has the protrusion 1A at the distal end thereof, according to the present invention, as shown in FIG. 2(c). The outer wall surface of this protrusion 1A is preferably parallel to the perpendicular direction. The distance (y), in FIG. 4(a), of the overlap portion between the long nozzle 2 and the stopper protrusion 1A, is set to 0.1 to 200 mm and the opening area of the long nozzle is set to 0.5 to 10 cm 2 . Moreover, the inner wall surface at the upper part of the long nozzle 2 is, or is not, brought into contact with the outer wall surface of the protrusion of the stopper so as to feed the molten alloy 6 from the ladle 3 to the tundish. Here, the term "long nozzle upper portion" means the upper end side of the long nozzle. That is, the portion near the end portion of the long nozzle connected to the ladle. More concretely, the term represents the portion within the range of about 200 mm from the uppermost end of the long nozzle towards its lower portion end. The long nozzle used for the method of the present invention is limited to those which have a shape such that the inner wall surface of this upper opening portion is parallel to the perpendicular direction. The term "inner wall surface of upper opening portion" refers to the inner wall surface of the opening indicated by reference numeral 2A in the sectional view of the long nozzle 2 in the perpendicular direction shown in FIG. 4(a). In the long nozzle 2 used for the method of the present invention the inner wall surface 2A of the upper opening portion is in parallel with the perpendicular direction means that the sectional shape of the opening portion of the long nozzle 2 in the horizontal direction has the same shape within the range of about 200 mm from the uppermost end of the long nozzle 2 towards its lower end. An important feature of the method of the present invention resides in that it uses the stopper 1 having the protrusion 1A whose outer wall surface is in parallel with the perpendicular direction. The arrangement wherein the outer wall surface of the protrusion 1A is in parallel with the perpendicular direction means that the sectional shape of the protrusion 1A in the horizontal direction has the same shape throughout the full length. FIGS. 4(a) and (b) show the best feeding method for practicing the method of the present invention. In FIG. 4(a), two positions are shown as the stop positions of the ladle stopper 1 used for the method of the present invention. That is, the position before the start of the feed of the molten alloy 6 to the tundish and the position during the feed of the molten alloy 6. In other words, the dotted line represents the former position and the solid line represents the latter position. FIG. 4(b) is an enlarged view showing the location near the fitting portion between the ladle stopper 1 and the long nozzle 2 when the ladle stopper 1 is at the position at which the molten alloy is flowing into the tundish. FIG. 5(a) is a sectional view taken along a line IV--IV in FIG. 4(b). FIG. 4(a) illustrates an example where the ladle stopper 1 has a circular cylindrical shape and the long nozzle 2 has a cylindrical shape as illustrated are in FIG. 5(a). The "distance (y) of the overlap portion between the long nozzle 2 and the stopper protrusion 1A" and the "opening area (Ao) of the long nozzle" used in the present method will be explained with reference to FIG. 4(a). First, the term "distance (y) of the overlap portion between the long nozzle 2 and the stopper protrusion 1A" is the distance represented by symbol y in FIG. 4(b). It is the distance of the area where the protrusion 1A of the ladle stopper 1 overlaps with the long nozzle 2 in the horizontal direction during the feed of the molten alloy. The case where this y value is from 0.1 to 200 mm will be explained in detail. The term "opening area (Ao) of the long nozzle" is the area represented by symbol Ao in FIG. 5(a) to FIG. 5(d). It is the sectional area of the space defined by the inner wall surface 2A of the opening at the upper part of the long nozzle and the outer wall surface of the protrusion 1A of the stopper 1. In the method of the present invention, the Ao value is limited to 0.5 to 10 cm 2 . In the method of the present invention, the sectional shape of the long nozzle in the horizontal direction is the same as the sectional shape of the protrusion of the stopper in the horizontal direction within the range of the distance y. Therefore, the value of the opening area Ao of the long nozzle has a constant value within the range of the distance y. The reasons why the distance (y) of the overlap portion between the long nozzle 2 and the stopper protrusion 1A is limited to 0.1 to 200 mm and why the opening area (Ao) of the long nozzle is limited to 0.5 to 10 cm 2 in the method of the present invention will be explained. It has been discovered that even when the y and Ao values shown in FIGS. 3 and 4(a), (b) , and FIGS. 5(a) to (d) are limited to 0.1 to 200 mm and to 0.5 to 10 cm 2 , respectively, the feed quantity of the molten alloy is set to a rate not greater than 100 kg/min. This is why the distance (y) of the overlap portion between the long nozzle and the stopper protrusion is limited to 0. 1 to 200 mm and the opening area (Ao) of the long nozzle is limited to 0.5 to 10 cm 2 . Preferred combinations of the distance (y) of the overlap portion between the long nozzle and the stopper protrusion with the opening area (Ao) of the long nozzle will be illustrated concretely in the later-appearing Examples. Fundamentally, however, when the Ao value is decreased within the range described above, the y value can be decreased within the range described above. Their values may be suitably selected in accordance with a predetermined feed quantity for the molten alloy. If the Ao value is less than 0.5 cm 2 , however, clogging of the nozzle is likely to occur even though the feed is the amorphous alloy. For this reason, the method of the present invention limits the Ao value to at least 0.5 cm 2 . On the other hand, the reason why the upper limit of the Ao value is set to 10 cm 2 is to place an upper limit on the y value. The reason why the upper limit is placed on the y value is that problems would occur in fitting the stopper or during its opening and closing operations if the y value is excessively large. For these reasons, the y value is limited to not greater than 200 mm. When the y value exceeds 200 mm, centering with the long nozzle becomes difficult and fitting of the stopper also becomes difficult. If centering of the stopper with the long nozzle becomes inferior, the opening and closing operations of the stopper cannot be carried out smoothly. When the y value is set to 200 mm, the Ao value can be increased up to 10 cm 2 . This is the reason why the upper limit of Ao value is set to 10 cm 2 . The reason why the upper limit of y is 200 mm is described above. The reason why the lower limit of y is 0.1 mm is to stably set a predetermined Ao value. The stopper of the present invention is the stopper for controlling the feed quantity of the molten alloy for producing the amorphous alloy thin strip which is characterized in that the stopper has a thin protrusion, with the length of this protrusion being at least 5 mm. The outer wall surface of the protrusion is in parallel with the perpendicular direction. Here, the term "thin protrusion" means that the protrusion is so thin that it can be fitted into the opening of the long nozzle at the fitting portion with the long nozzle. The length of the protrusion of the stopper is limited to at least 5 mm. The stopper stroke must be at least 5 mm as previously discussed and the y value must be at least 0.1 mm. The discovery that "the feed quantity of the molten alloy can be set to a rate not greater than 100 kg/min even when the stopper stroke is greater than 5 mm by setting the y and Ao value to 0. 1 to 200 mm and to 0. 5 to 10 cm 2 , respectively" was made performing experiments using the Fe-B-Si-C system amorphous alloy. This phenomenon results from the fact that the viscosity of an amorphous alloy in the molten state is far smaller than that of ordinary crystalline alloys. Since this phenomenon does not only occur in the Fe-B-Si-C system amorphous alloy but is believed to occur in a broad range of alloys that can be converted to amorphous alloys, the present invention can be widely applied to a variety of amorphous alloys. According to the method of the present invention, the molten alloy can be provided supplied at a constant feed rate of not greater than 100 kg/min even when the position of the ladle stopper is fixed once the ladle stopper is moved upward at the time of the start of the feed of the molten alloy. Since the method of the present invention does not require the position of the ladle stopper to be moved up and down so as to control the flow rate of the molten alloy as has been necessary in the prior art, the operation can be carried out easily. Since the present invention does not require a complicated apparatus, it can economically supply the molten alloy. When the height of the molten metal level in the tundish fluctuates to some extent due to the effect of the decrease of the molten metal level inside the ladle in the present invention, it is advisable to eliminate the fluctuation of the molten metal level in the tundish by inserting a dummy volume, for example, into the tundish and moving up and down this dummy volume in accordance with the fluctuation of the molten metal level of the tundish. A change of the height of the molten metal level in the tundish can cause fluctuation of the jet pressure of the molten alloy impinging on the cooling roll. Eventually, this can cause a fluctuation in the sheet thickness of the resulting thin strip. Thin strips having a large thickness fluctuation generally cause problems when used as industrial materials. The method of inserting the dummy volume into the tundish and keeping constant the height of the molten metal level in the tundish is an economical method and does not significantly increase the production cost of the thin strip. The present invention does not specifically limit the stopper stroke of the ladle stopper at the start of the feed of the molten alloy. In view of the vibration of the apparatus, it is not preferred to set the stroke to an excessively small value. Preferably, therefore, the range of the stopper stroke is from about 5 to about 50 mm. FIGS. 4(a) and (b) show the case where a circular cylindrical long nozzle is used by way of example. However, the shape of the long nozzle used for the method of the present invention is not specifically limited to a circular cylindrical shape. The sectional shape of the long nozzle may be circular, elliptic, flower-like or polygonal. FIGS. 5(a) to (d) are sectional views taken along a line II--II of FIG. 4(a) and line IV--IV of FIG. 4(b). FIG. 5(b) shows the long nozzle 2 having different shapes on the outside and the inside, that is, a circular outer shape and a flower-like opening shape. Further, the shape of opening of the long nozzle can be different at its upper and lower portions. The present invention does not particularly limit the sectional shape of the protrusion on the stopper. When the shape of the opening of the long nozzle 2 is flower-shaped as shown in FIG. 5(b), for example, the shape of the overlap portion between the stopper 1 and the long nozzle 2 also may be flower-shaped. Needless to say, the sectional shape of the opening of the long nozzle 2 in the horizontal direction does not have to be similar to the sectional shape of the protrusion 1A of the stopper 1 in the horizontal direction as shown in FIGS. 5(c) and 5(d), for example. In other words, FIGS. 5(c) and (d) are sectional views taken along the line IV--IV in FIG. 4(b). As can be appreciated from FIG. 5(c), the sectional shape of the protrusion 1A may be different in the horizontal direction from the sectional shape of the opening of the long nozzle 2 such as in the combination of the stopper 1 having the protrusion 1A whose sectional shape is elliptic used with a circular cylindrical long nozzle 2. The preferred thin strip production apparatus used by the present invention is the single roll apparatus or the twin roll apparatus for jetting the molten alloy through the nozzle to the cooling substrate and quenching and solidifying the molten alloy by the thermal contact. The single roll apparatus includes a centrifugal quenching apparatus using the inner wall of a drum, an apparatus using an endless type belt, and improvement types such as those equipped with an auxiliary roll, a roll surface temperature controller, or casting in an inert gas or in vacuum at a reduced pressure. The casting conditions used for the method of the present invention and specific casting operations will be explained. The jet pressure of the molten metal is 0.01 to 3 kg/cm 2 . It is set primarily by using the height of the molten metal level inside the tundish. The rotating speed (surface speed) of the cooling roll is within the range of 5 to 60 m/sec. Optimum values are selected for these conditions in accordance with the type of the alloys used, the thickness of the intended strips and other production conditions. According to one embodiment of the method of the present invention, at least one portion of the outer wall surface of the protrusion of the stopper is brought into contact with the inner wall surface of the opening at the upper portion of the long nozzle during supplying the molten alloy 6 from the ladle 3 into the tundish 5. Here, the term "outer wall surface of the protrusion of the stopper is brought into contact with the inner wall surface of the opening at the upper portion of the long nozzle" represents the state shown in FIGS. 5(c). These drawing figures show embodiments where two portions of the outer wall surface of the protrusion 1A of the stopper 1 are in contact with two portions of the inner wall surface 2A of the opening at the upper portion of the long nozzle 2. The term "outer wall surface of the protrusion of the stopper is brought into contact with the inner wall surface of the opening at the upper portion of the long nozzle" represents such a state. When the outer wall portion of the protrusion of the stopper is brought into contact with the inner wall surface of the opening at the upper portion of the long nozzle, centering of the long nozzle with the stopper becomes easier. Therefore working factors during the production of the thin strip can be improved, and the supply of the molten alloy becomes easier. EXAMPLE 1 The production of a Fe-B 12 Si 6 .5 C 1 (at %) alloy thin strip was carried out by using a single roll thin strip production apparatus as shown in FIG. 1. The molten alloy was in a ladle equipped with a ladle stopper and with a long nozzle as shown in FIG. 3. The ladle stopper used was of an ordinary type having an elliptic distal end (to which a fine protrusion may be attached). The long nozzle was made of alumina graphite and its inner sectional shape was circular. It had an inner diameter of 30 mm at the uppermost portion, an inner diameter of 12 mm at the lowermost portion, and a length of 1 m. The distance (y) of the overlap portion between the distal end portion of the ladle stopper and the distal end portion of the long nozzle was adjusted to 0.08 mm. The opening area inside the nozzle was 1.13 cm 2 and the distance (Lm) from the ladle bottom surface to the minimum sectional area position inside the long nozzle was 1 m. Melting of the alloy was effected by a radio frequency induction system. The height of the molten alloy level inside the ladle before the start of feeding the molten alloy to the tundish was 250 mm. In other words, the height (Ln) of the level of the molten metal inside the ladle at the start of feeding the molten metal was 250 mm and the Ln/Lm value was 4 in this experiment. The ladle stopper used was made of alumina graphite, the same as the long nozzle, and had a cylindrical shape, a length of 800 mm and an outer diameter of 60 mm. A radius of curvature (combination of R 120 mm and R 15 mm) was applied to only the portion having a length of 35 mm at the distal end. The molten alloy was guided into the tundish by moving up the ladle stopper 20 mm. Immediately thereafter, the production of the thin strip was started by moving up the tundish stopper 20 mm. Both of the ladle stopper and the tundish stopper were kept at the 20 mm elevated positions until the production of the thin strip was completed. Other thin strip production conditions were as follows. Molten alloy temperature inside ladle at charging: 1,350° C.; nozzle opening shape: opening formed by aligning two rectangular slits having a size of 120 mm×0.7 mm with a 1.5 mm-gap; surface speed of cooling roll at casting: 20 m/sec; gap between nozzle and cooling roll: 0.3 mm. As a result, a thin strip having a width of about 120 mm and good properties could be obtained. Samples each having a length of 20 m were collected from the resulting thin strip at five positions spaced apart equidistantly in the longitudinal direction. The weight of each sample was measured. The weight was found to be about 0.95 kg for all the samples. Since each 20 m-long sample was the quantity of the thin strip produced within one second, the quantity of the molten alloy supplied to the tundish was about 57 kg/min. The thickness of the resulting thin strip was about 55 μAm. Fluctuation of the thickness in the longitudinal direction of the thin strip hardly existed. The thin strip so obtained was excellent in both magnetic and mechanical properties. It can be understood from the results described above that the feed quantity of the molten alloy by such a supplying method of the molten alloy was not greater than 100 kg/min and the molten alloy could be uniformly supplied during casting. EXAMPLE 2 The production of a Fe-B 12 Si 6 .5 C 1 (at %) alloy thin strip was carried out by using a single roll thin strip production apparatus as shown in FIG. 1. The molten alloy was in a ladle equipped with a ladle stopper and a long nozzle as shown in FIG. 4(a). The long nozzle used was made of alumina graphite and had a cylindrical shape. It had an inner diameter of 40 mm at the uppermost portion, an inner diameter of 25 mm at the lowermost portion, and a length of 1 m. The inner diameter had a constant value at the portion of a length of 200 mm from the upper-most portion to the lower portion. The lower portion had a predetermined taper. The long nozzle had an outer diameter of 60 mm for the portion having a distance of 200 mm from the uppermost portion towards the lower portion, and the outer diameter was 40 mm at the lowermost portion. The ladle stopper was made of alumina graphite, had a circular cylindrical shape having a length of 860 mm and an outer diameter of 60 mm. It had a circular cylindrical protrusion having a length of 60 mm at the distal end thereof as shown in FIG. 4(b). Three kinds of ladle stoppers were used and the diameter of the protrusion at the distal end of each stopper was changed. Here, the protrusion at the distal end of the stopper and the long nozzle were arranged in such a fashion that they did not come into contact with each other so as to secure the opening area Ao, as shown in FIG. 5(a), (b). Melting of the alloy was effected by a radio frequency induction system. The height of the molten metal level inside the ladle before the start of feeding of the molten alloy to the tundish was 250 mm. The casting experiment was carried out with one charge for each of three kinds of ladle stoppers, that is, three charges in total. As the conditions for each casting experiment for each charge, the values of y and Ao shown in FIG. 4(a), (b) and FIG. 5(a), (b) and the value of the stopper stroke (Ls) of the ladle stopper were tabulated in Table 1. Other thin strip production conditions were as follows. Molten alloy temperature inside ladle at charging: 1,350° C.; nozzle opening shape: opening formed by aligning two rectangular slits having a size of 120 mm×0.7 mm with a 1.5 mm gap; surface speed of cooling roll at casting: 24 m/sec; gap between nozzle and cooling roll: 0.25 mm. As a result, a thin strip having a width of about 120 mm and having excellent properties was obtained. Samples, each having a length of 24 m, were collected from the resulting thin strips at five positions spaced apart equidistantly in the longitudinal direction, and the weight of each sample was measured. Since this weight represented the weight of the molten alloy supplied within one second, the feed quantity of the molten alloy at the time of casting was calculated from this data. The minimum and maximum values were tabulated in Table 1 as the results. TABLE 1______________________________________ resultcasting condition feed q'ty of strip y A.sub.o L.sub.s molten alloy thicknessNo mm cm.sup.2 mm kg/min μm______________________________________1 18 1.8 42 69-71 53-552 28 2.4 32 65-69 49-523 43 3.5 17 85-88 60-63______________________________________ As can be understood from this table, the values of the molten alloy feed quantity from the charge were substantially constant for each charge. The strip thickness of each of the 24 m-long samples collected was measured. The minimum and maximum values of the strip thickness of each sample were also tabulated in Table 1. A great fluctuation in the thickness of the thin strip could not be observed in any charge. It can be understood from this data that no fluctuation which would become a problem from the molten alloy feed quantity occurred in all the charges. The resulting thin strips were excellent in both magnetic and mechanical properties. It can be understood from the results given above that the supplying method of the molten alloy can supply the molten alloy at a feed quantity of not greater than 100 kg/min and furthermore, substantially uniform during casting. EXAMPLE 3 Production experiments for thin strips were carried out by using the same thin strip production apparatus as in Example 2. The ladle stopper had a circular cylindrical shape having a length of 900 mm and an outer diameter of 60 mm. It had a circular cylindrical protrusion having a length of 100 mm at the distal end thereof as shown in FIG. 4(a), (b). Three kinds of ladle stoppers were used, and the diameter of the protrusion at the distal end of each ladle stopper was changed. The casting experiments were carried out by changing the values y and Ao shown in FIGS. 4(a), (b) and 5(a), (b). The values y and Ao used for the respective casting experiments were tabulated in Table 2. The surface speed of the cooling roll was set to 26 m/sec, and other casting conditions were the same as those of Example 2. As a result, thin strips having a width of about 120 mm and good properties could be obtained in all the charges. Samples each having a length of 26 m were collected from the resulting thin strips in the same way as in Example 1. The feed quantity of the molten alloy and the thickness of the thin strips were examined. Table 2 shows the results in the same way as in Table 1. From the data of the feed quantity of the molten alloy and the thickness of the thin strips tabulated in Table 2, fluctuation of the feed quantity of the molten alloy could not be observed in any charge. Fluctuations which would become the problem in the thickness of the thin strips could not be observed. TABLE 2______________________________________ resultcasting condition feed q'ty of strip y A.sub.o L.sub.s molten alloy thicknessNo mm cm.sup.2 mm kg/min μm______________________________________1 62 5.5 38 72-75 52-562 76 6.4 24 63-65 47-513 88 7.3 12 66-69 49-52______________________________________ It can be understood from the results given above that the supplying method of the molten alloy can supply the molten alloy at a feed quantity of not greater than 100 kg/min and furthermore, is substantially uniform during casting. EXAMPLE 4 The production of a Fe-B 12 Si 6 .5 C 1 (at %) alloy thin strip was carried out by using a single roll thin strip production apparatus shown in FIG. 1. The molten was in a ladle equipped with a ladle stopper and with a long nozzle as shown in FIG. 4(a). The long nozzle used was made of alumina graphite and had a cylindrical shape as shown in FIG. 4(a), (b). It had an inner diameter of 40 mm at the uppermost portion, an inner diameter of 25 mm at the lowermost portion and a length of 1 m. The inner diameter had a constant value at the portion of a length of 200 mm from the uppermost portion. The lower portion had a predetermined taper. The long nozzle had an outer diameter of 60 mm for the portion having a distance of 200 mm from the uppermost portion towards the lower portion, and the outer diameter was 40 mm at the lowermost portion. The ladle stopper was made of alumina graphite, had a circular cylindrical shape having a length of 900 mm, an outer diameter of 100 mm, and had an elliptic protrusion having a length of 60 mm at the distal end thereof as shown in FIG. 5(c). The major diameter of this elliptic protrusion was 40 mm. The stopper was in slight contact with the inner wall surface of the opening at the upper portion of the long nozzle at two position at both ends of the major diameter. Three kinds of ladle stoppers were used. The minor diameter of the elliptic shape of the protrusion at the distal end of each stopper was changed. Melting of the alloy was effected by a radio frequency induction system. The height of the molten metal level inside the ladle before the start of the feeding of the molten alloy to the tundish was 250 mm. The casting experiment was carried out in one charge for each of three kinds of the ladle stoppers, i.e., three charges in total. The values of y and Ao shown in FIG. 4(a), (b) and FIG. 5(c) and the value of the stopper stroke (Ls) of the ladle stopper, as the condition of each casting experiment, are tabulated in Table 3. Other thin strip production conditions were as follows. Molten alloy temperature inside ladle at charging: 1,350° C.; nozzle opening shape: opening formed by aligning two rectangular slits having a size of 120 mm×0.7 mm with a 1.5 mm-gap surface; speed of cooling roll at casting: 24 m/sec; gap between nozzle and cooling roll: 0.25 mm. As a result, thin strips having a width of about 120 mm and good properties could be obtained in all of the charges. Samples each having a length of 24 m were collected from the resulting thin strips at five positions spaced apart equidistantly in the longitudinal direction. The weight of each sample was measured. Since this weight represented the weight of the molten alloy supplied for 1 second, the feed quantity of the molten alloy at the time of casting was calculated from this data. The minimum and maximum values of the results were tabulated in Table 3. The feed quantity of the molten metal in the charge was substantially constant for each charge as can be understood from these values. The sheet thickness was measured for each of the 24 m-long samples so collected. The minimum and maximum values of the strip thickness so obtained were also tabulated in Table 3. A great fluctuations could not be observed in the thickness of the thin strip for each charge. It could be understood from this data that no fluctuation which would become a problem resulting from the molten alloy feed quantity occurred in any of the charges. The resulting thin strips were excellent in both magnetic and mechanical properties. It can be understood from the results given above that the supplying method of the molten alloy can supply the molten alloy at a feed quantity of not greater than 100 kg/min and furthermore, substantially uniformly during casting. TABLE 3______________________________________ resultcasting condition feed q'ty of strip y A.sub.o L.sub.s molten alloy thicknessNo mm cm.sup.2 mm kg/min μm______________________________________1 58 5.2 42 68-72 54-572 78 6.5 22 64-67 50-543 89 8.1 11 65-69 52-55______________________________________ EXAMPLE 5 Production experiments for thin strips were carried out by using the same thin strip production apparatus as in Example 4. A ladle stopper had a circular cylindrical shape, a length of 900 mm and an outer diameter of 60 mm. It had a flower-shaped protrusion having a length of 60 mm at the distal end thereof as shown in FIG. 5(d). The y and Ao values shown in FIGS. 4(a), (b) and 5(d) were 13 mm and 1.5 cm 2 , respectively. The other casting conditions were the same as those of Example 4. As a result, thin strips having a width of about 120 mm and good properties could be obtained. Samples were collected from the resulting thin strips in the same way as in Example 1. The feed quantity of the molten alloy and the thickness of the thin strips were examined. As a result, it was found out that the feed quantity of the molten alloy was 62 to 64 kg/min and the thickness of the thin strips was 49 to 52 μm. Fluctuation of the feed quantity of the molten metal could not be observed from these data and fluctuations which would become a problem resulting from molten alloy feed quantity could not be observed. It can be understood from the results given above that the supplying method of the molten alloy can supply the molten alloy at a feed quantity of not greater than 100 kg/min and, furthermore, substantially uniform during casting.

A method for supplying molten metal alloy for producing thin amorphous metal wire or thin amorphous metal strip by liquid quenching and solidification on a moving cooling substrate controls the flow of molten metal from a ladle into a tundish. The ladle has a long nozzle with an interior passage for providing flow of molten metal alloy into the tundish. The ladle stopper has a distal end region received by the interior passage of the long nozzle. Control of the overlap between the distal end region of the ladle stopper received in the long nozzle during molten alloy flow and control of the sectional flow area provided in the long nozzle interior passage controls the flow quantity of molten alloy from the ladle into the tundish.

This application claims priority to provisional application Ser. No. 60/000,671 Jun. 30, 1995. FIELD OF THE INVENTION The present invention relates to a draw-down applicator for use in preparing draw-down samples, and more particularly for use in preparing draw-down samples of a coating. The present invention additionally relates to a method and kit for preparing draw-down samples. BACKGROUND OF THE INVENTION Paint customers generally select paint based upon relatively small cards having multiple colors. These cards are often referred to as "paint chips." After a paint is purchased and applied to a surface, it is sometimes found that the color of the paint does not match the color of the paint chip because of errors in formulating or mixing the paint. Improperly formulated or mixed paint is frustrating for customers, and returned paint and unsatisfied customers can be bad for a paint store's business. Accordingly, paint samples are often prepared to compare the color of recently mixed paint to the color of paint chips. Paint samples for comparing recently formulated and mixed paint to a paint chip should be sufficiently large and have a consistent film thickness so that light is properly absorbed and reflected by the sample. Accordingly, a paint brush or a roller should be used to provide a smooth surface and a sufficient thickness of paint. Using a brush or roller, however, is generally too expensive and time consuming since the brush or roller would have to be thrown out or cleaned after each use. High precision film applicators have been used in laboratories to provide coatings having precise thicknesses. For example, see BYK Gardner Catalog 90, by BYK-Gardner, Inc., Silver Spring, Md. 20910. These bars, however, are made of steel and require machining to very high tolerances, thereby increasing their expense. In addition, the film applicators are too heavy to be used conveniently, can become misaligned if dropped, and may rust or pit in water or other solvent. In order to provide a paint sample for comparison, many paint stores provide a "finger smear" of paint on a piece of scrap paper. Generally, a store clerk prepares a finger smear by dipping his finger into a can of paint and smearing the paint onto a piece of scrap paper. The clerk then either wipes off his finger or marks everything he touches with wet paint. Accordingly, a need exists for an inexpensive and convenient alternative device and method for providing samples of paint. Paint customers often desire to purchase paint which matches paint previously purchased. Many paint stores have a spectrophotometer which measures the light reflected from a sample of the paint, and an accompanying computer calculates the proper mix of pigments to provide a matching paint composition. To provide a sample for the spectrophotometer, a store clerk will prepare a paint sample on a piece of paper. Usually, the paint sample is a finger smear. Since the surface is uneven, the paint does not accurately reflect light and the correct color of the paint is often miscalculated. Since the thickness of the paint prepared by a finger smear is not uniform, thin portions can have insufficient opacity, and thereby allow the substrate color to show through. The thick portions may take some time to dry and may remain wet when handled by the customer. SUMMARY OF THE INVENTION A draw-down applicator is provided by the present invention. The draw-down applicator includes a drawing plate, a first support, and a second support. The drawing plate has a bottom drawing surface, a bottom fluid delivery surface, and first and second ends. The first support includes a bottom sliding surface and can be rigidly connected to the first end of the drawing plate. The second support has a bottom sliding surface and can be rigidly connected to the second end of the drawing bar. The bottom sliding surfaces of the first and second supports form a first plane, and the bottom drawing surface of the drawing plate forms a second plane which is parallel but not coplanar with the first plane. In a preferred embodiment of the invention, the first and second supports of the draw-down applicator each have a top sliding surface which forms a third plane; and the drawing plate has a top drawing surface which is in a fourth plane, and a top fluid delivery surface. In this embodiment, the third and fourth planes are parallel but not coplanar. The applicator is preferably made from a lightweight, non-metallic material resistant to paint solvents. The material can be anything which does not require machining, and which can be molded, preferably by injection molding. Polymeric or plastic materials are preferred. It should be appreciated that the phrase "non-metallic material" is not meant to exclude catalysts or fillers which may contain metal. Rather, it is preferred that the material is one which can be molded rather than machined into a desired shape. Exemplary polymeric materials which can be used in the invention include melt processable thermoplastic materials such as acrylonitrile butadiene-styrene resin, polystyrene, polyamide, polycarbonate, polyester, polyethylene, polypropylene, polyurethane, and mixtures thereof. In a preferred embodiment, the first plane and the second plane, and the second and third planes, respectively, are separated by a distance which is sufficient to provide a draw-down sample of a desired fluid. If the fluid has a low viscosity, the separation can be small, such as about 1 mil. If the fluid has a high viscosity or if a thick layer of the fluid is desired or if aggregate is included in the fluid, a larger distance may be desired, such as 1/8 inch. It is believed that in most applications involving latex paint as the fluid, the distance will be between about 5 mil and 10 mil. An advantage of the draw-down applicator of the invention is that it is lightweight and can be conveniently used, for example, by paint store clerks. Generally, the draw-down applicator has a weight of less than about 0.5 pound. More preferably, the weight is less than about 2 ounces, and even more preferably less than about 1 ounce. In order to provide sufficient structure, it may be difficult to provide a draw-down applicator having a weight of less than 0.1 ounce. A draw-down applicator made of acrylonitrile-butadiene-styrene resin and having drawing surfaces of about 2 inches, a drawing plate depth of about 3/16 inch and width of about 15/16 inch, and two legs having lengths of about 1.1 inch and widths of about 15/16 inch has a weight of about 0.5 ounce. A method for preparing a draw-down sample of a fluid is provided by the present invention. One step in the method includes forming a puddle of fluid on a substrate having a substantially smooth surface and wherein the substrate is separable at a predetermined location into at least two pieces. It should be appreciated that commercially available paper is generally sufficient to provide a substantially smooth surface. Although certain imperfections may be present in the substrate, a more macroscopic view should be used in determining what is "smooth." In addition, separable locations can be provided by perforations, scoring, bending and the like. Additional steps of the method include providing a draw-down applicator, and drawing the draw-down applicator over the puddle of fluid to provide a sample of the fluid having a substantially uniform thickness. It should be appreciated that a "substantially uniform thickness" describes a layer of fluid which can be provided by the draw-down applicator of the present invention. Generally, it is believed that the sample of fluid having a substantially uniform thickness will be provided on commercially available paper and may have imperfections caused by the texture of the paper. The method can additionally include a step of removing a dipper from the substrate and using the dipper to scoop the fluid and apply it to the substantially smooth surface. Furthermore, the method can include allowing the drawn fluid to dry, and separating the substrate along a predetermined separable location to provide at least two separated substrates having drawn fluid thereon. It is particularly preferred that the fluid is paint. Alternative fluids, such as, ink, stain, protective finish, and the like, can be used in by the present invention. A kit for preparing draw-down samples is provided by the present invention. The kit includes a draw-down applicator and a substrate separable at a predetermined location. The substrate is preferably paper which is separable to provide a dipper section and a fluid coatable section. The kit can additionally include a portable smooth and rigid platform which can be used to provide a smooth surface against which the substrate is placed and the draw-down applicator is drawn. Preferably, the kit includes a wash basin for washing the applicator. The wash basin can be a bucket or bowl having sufficient dimensions to hold enough water or other solvent to satisfactorily clean the draw-down applicator after it has been used. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a draw-down applicator according to the principles of the present invention; FIG. 2 is a front view of the draw-down applicator of FIG. 1; FIG. 3 is cross sectional view taken along line 3--3 of the draw-down applicator of FIG. 1; FIG. 4 is a top view of a draw-down card according to the principles of the present invention; FIG. 5 is a bottom view of the draw-down card shown in FIG. 4; and FIG. 6 is a perspective view, in operation, of a kit for preparing a draw-down sample. DETAILED DESCRIPTION OF THE INVENTION The preferred embodiment of the invention will be described in detail with reference to the drawings, wherein like reference numerals represent like parts and assemblies throughout the several views. Reference to the preferred embodiment does not limit the scope of the invention, which is limited only by the scope of the claims attached hereto. Referring to FIGS. 1-3, an embodiment of a draw-down applicator of the present invention is provided at 10, and may be referred to as the applicator. The draw-down applicator 10 includes drawing region 12, first guiding region 14, and second guiding region 16. Preferably, the applicator 10 is an integral piece. It is to be understood that the word "integral" refers to the draw-down applicator 10 being a continuous material which does not separate into subparts except by fracturing. Alternatively, the applicator can be made of parts which snap together to provide an assembled applicator. The drawing region 12 includes a drawing plate 18 having a bottom drawing surface 20 and a bottom fluid delivery surface 22, and a top drawing surface 24 and a top fluid delivery surface 26. As a matter of convenience, one side of the applicator 10 can be referred to as the top side 15 and the opposed side can be referred to as the bottom side 17. It should be appreciated that the designation of "top" and "bottom" reflects opposed surfaces or sides of the applicator 10. Since the applicator 10 is so small and lightweight, it can easily be turned over so that the bottom side 17 is above or "on top of" the top side 15. As will be described in more detail, the fluid delivery surfaces 22, 26 are provided to meter or control the flow of fluid to the drawing surfaces 20, 24 to form a thin film of fluid on a substrate when the applicator 10 is drawn over a puddle of fluid. Accordingly, the angle of the fluid delivery surfaces 22, 26 to the drawing surfaces 20, 24 is provided based upon intended flow properties. One having skill in the art would readily appreciate how fluid rheology effects these angles. For many latex paints, it is acceptable to provide a 45 degree angle as shown. The first guiding region 14 includes a first leg 19 having a bottom sliding surface 28 and a top sliding surface 30. Similarly, the second guiding region 16 includes a second leg 23 having a bottom sliding surface 32 and a top sliding surface 34. The bottom drawing surface 20 lies in a bottom drawing plane which is parallel to the bottom sliding plane formed by the bottom sliding surfaces 28, 32. Similarly, the top drawing surface 24 lies in a top drawing plane which is parallel to the top sliding plane formed by the top sliding surfaces 30, 34. It should be understood that the bottom drawing surface need not entirely be within the bottom drawing plane, and that the top drawing surface need not entirely be within the top drawing plane. In other words, the drawing surfaces can be provided at any desired angle to the sliding surfaces. However, the bottom drawing plane is not coplanar with the bottom sliding plane, and the top drawing plane is not coplanar with the top sliding plane. It is the discontinuity between these plane, or expressed differently, it is the discontinuity along the surfaces 28, 20, 32 and along the surfaces 30, 24, 34 which is important for providing slots 21, 25, respectively, which allow the draw-down applicator 10 to provide draw-down samples as will be described in more detail. The slots 21, 25 are provided with sufficient depth to provide a desired thickness of fluid to flow therethrough. Preferably, the coating provided by the applicator has a substantially uniform thickness on a substrate. It is to be understood that a "substantially uniform thickness" is meant to include a coating on paper where the coating can have irregularities due to pores or fibers therein. For applicator 10, as an example, the distance between the bottom drawing plane and the bottom sliding plane is 8/1000 inch (8 mils) and is indicated by the raised markings 40 on the front of the drawing plate 18. The distance between the top drawing plane and the top sliding plane is 6/1000 inch (6 mils) and is indicated by the raised markings 42. It has been found that for most commercially available paints, these slot sizes are sufficient for providing adequate draw-down samples. For most applications, the slot depth should be above about 1 mil and less than about 10 mil. However, alternative slot sizes can be provided depending, for example, on the viscosity of the fluid and the desired thickness of the coating. The beveled surfaces 46, 48, 51, 53, 55, 56 are provided to reduce the angle of the edges and to reduce the amount of material used to prepare the applicator 10. This additionally keeps the applicator lighter in weight. In addition, the beveled surfaces 51, 53, 55, 56 help reduce the surface area of the sliding surfaces 28, 30, 32, 34 which helps reduce friction and allows the applicator 10 to slide or glide more easily over the surface of a substrate. When the applicator 10 is used to provide a draw-down sample, either the top side 15 or the bottom side 17 is slid across the surface of a substrate. Preferably, the surface of the substrate is a substantially smooth surface. As used herein, a "substantially smooth surface" is a surface which is sufficiently even and uniform to provide a draw-down sample having a relatively consistent coating or film thickness using the draw-down applicator of the present invention. Generally, commercially available paper would be capable of providing a substantially smooth surface. To help provide a substantially smooth surface, a smooth and rigid platform can be placed under the substrate. Exemplary platforms include fixed or relatively immovable objects such as tables, counters, desks, and the like, or portable objects such as glass or metal plates, plexiglass, fiberglass, or other plastic sheet, and the like. A substrate which can be used to provide a draw-down sample according to the present invention is provided in FIGS. 4 and 5, and is referred to as draw-down card 50. The draw-down card 50 has a first side 52 and a second side 54. The draw-down card 50 includes perforations 56, 58, 60 which allow for separation of portions of the card into take home section 62, retention section 64, excess paint section 66, and a dipper section 68. It is preferred to provide a draw-down sample across the first side of the take home section 62 and the retention section 64. It is noted that in place of the perforations, the card can have slits, scoring, indentations, markings, and the like which identify a suitable area for separation by, for example, tearing, cutting, etc. In a preferred embodiment for providing a draw-down sample of latex paint, the dipper section 68 is removed and folded along score line 69 to provide a V-shaped dipper. The remaining part of the card 50 can be placed on a flat and level surface with the first side up. The dipper can be dipped into the paint, and the paint in the dipper can be applied over the paint application line 70 to substantially cover the line and form a puddle of paint. It should be appreciated that the size of the line 70 can be used to indicate a predetermined sufficient amount of paint needed to provide an acceptable draw-down sample. Once the paint has been applied, the dipper can be thrown away. The draw-down applicator 10 can be placed around the puddle of paint so that either the bottom sliding surfaces 28, 32 or the top sliding surfaces 30, 34 are resting on the first surface of the draw-down card 50. Thus, the legs 19, 23 are positioned around the puddle so that the drawing plate 18 is ready to engage the puddle once the applicator 10 is drawn thereover. If the bottom side of the applicator 10 is placed on the card 50, once the card is drawn, the fluid flows over the bottom fluid delivery surface 22 so that the bottom drawing surface 20 provides a coating having a consistent thickness on the card. Once the drawing plate 18 engages the puddle of fluid, the tendency of the fluid would be to spread out. The legs 19, 23, however, typically contain the fluid within the applicator 10 so that a draw-down sample having a width which is equal to the distance between the legs 19, 23 is provided. In a substantially continuous motion, the applicator 10 draws the puddle of paint over the sections 62, 64, 66. An embodiment showing the end of this drawing stage is provided in FIG. 6 showing plexiglass platform 71, draw-down sample 75, and puddle of excess paint 77. Once the draw-down sample 75 is completed, the draw-down applicator 10 can be placed in a wash-up bin or bucket filled with cleaning solution such as water or turpentine, and the excess paint section 66 can be removed along perforation 58 from the card 50 and discarded. The remaining sections 62, 64 can be hung on a hook via hole 72 until the paint dries. It is an advantage of the present invention that the applicator 10 can be easily cleaned since the surfaces are relatively smooth. Alternatively, the applicator 10 is sufficiently inexpensive that it can be disposed or recycled. Furthermore, it is an advantage that draw-down samples can be prepared without creating a mess and without requiring hand cleaning afterwards. The dipper 68 and the excess paint section 66 containing the puddle of excess paint 77 are discarded. It is another advantage that the draw-down card 50 containing a wet draw-down sample 75 can be hung in an out of the way place until the sample dries. Accordingly, the present invention provides for increased organization in preparing draw-down samples. The card 50 can include additional information. For example, the first side of the take home section 62 includes an area for identifying the paint 73, and the second side of the take home section 62 includes an area for identifying the application of the paint 74 and an area for identifying the paint store 76. The second side of the retention section 64 includes an area for identifying the customer and the paint. The take home section 62 can be kept by the customer and the retention section 64 can be kept by the paint store for its records. It should be appreciated that the draw-down card can be modified to provide any information desired. In addition, multiple draw-down cards can be prepared. For example, it may be desirable for architects or contractors to provide draw-down samples to clients along with plans. In such cases, it may be helpful to prepared additional draw-down samples for the store's records, for the architect's records, and for the client's records. Alternatively, the card can be modified to be used in other applications, such as in a laboratory. In such an application, for example, it may be desired to provide only two perforated line, one for separation of the dipper and one for separation of the excess paint section. It is an advantage of the present invention that relatively large samples of paint, or large paint chips, can be inexpensively and conveniently prepared and taken home by paint customers for evaluation. It is understood that paint often looks different in various lighting conditions, and/or when applied to a large surface. It is believed that by providing large samples of paint for customers to evaluate, customer satisfaction with selected paints will increase. Accordingly, the size of the applicator can be modified to provide a desired size draw-down sample. It is preferred that the width of the substrate on which the draw-down sample is prepared is larger than the overall width of the draw-down applicator. This helps provide a substantially consistent film thickness. It is an additional advantage of the present invention that the draw-down applicator can be easily and inexpensively prepared, and can provide desired accuracy in preparing a draw-down sample. As discussed above, high precision film applicators have been used in laboratories to provide coatings having precise thicknesses. These bars, however, are heavy and expensive. The applicator of the invention provides significantly low distribution costs due to its light weight. In addition, it is an advantage of the present invention that the draw-down applicator is light and easy to use, inexpensive to manufacture, and resists corrosion and pitting in water and many solvents commonly used in coating compositions. In addition, the draw-down applicator is sufficiently rigid to resist bending out of shape if dropped. It should be appreciated that many types of fluid can be used with the draw-down applicator and/or the draw-down card of the present invention. Preferably, the fluid is a type which provides a coating on a substrate. Exemplary fluids include paints such as latex and oil based paints, and consumer and industrial paints, finishes such as polyurethane and polyacrylic finishes, stains, and the like. A preferred fluid which can be used to provide a draw-down sample is latex paint since the draw-down applicator can be easily cleaned in water afterwards. The applicator 10 can generally be used on a level or tilted surface. It is desirable, however, that the surface is sufficiently level so as to resist the flow of fluid in any one direction caused by the force of gravity. It is understood that when a fluid is applied to a perfectly level surface, it theoretically will flow in all directions equally. It is desirable, however, that the draw-down applicator provides the force which displaces the fluid to provide the draw-down sample. It should be appreciated that the ability of a fluid to flow is a function of viscosity, and that certain paint compositions are intended to be applied to vertical walls. Thus, the degree of tilt or slant of the substrate is a function of the rheology of the paint composition. For example, if a paint if very viscous, it will resist flow caused by gravity. In contrast, a very low viscosity fluid may exhibit runny characteristics. It is generally desirable that when a paint composition is applied to the substrate, it remains in a puddle and does not flow until drawn by the applicator 10. The draw-down applicator of the present invention can be manufactured without machining. Preferably, the draw-down applicator is prepared, for example, by injection molding or compression molding. Materials which can be used to prepare the draw-down applicator are preferably polymeric materials resistant to solvents normally found in paint composition, and which are melt processable thermoplastics. Exemplary polymeric materials include acrylonitrile-butadiene-styrene (ABS) resin, polystyrene, polyamide, polycarbonate, polyester, polyethylene, polypropylene, polyurethane, mixtures thereof and the like. When preparing the draw-down applicator by injection molding, it is desirable for the walls to be as thin as possible to decrease manufacturing time, yet sufficiently thick to provide desired stability. Thicker walls generally take longer to cool before they can be removed from a mold. Preferably, the wall thickness should be in the range of about 1/4 to 1/16 inch. In order to decrease the wall thickness and provide a sufficiently high manufacturing rate, the first and second legs 19, 23 of the applicator 10 are provided with stabilizers 45 which allow the applicator 10 to be more quickly removed from an injection mold. The stabilizers 45 have a sufficient diameter which allow injector pins to push against the ends thereof to push the applicator out of the mold. Thus, as the diameter of the stabilizers 45 decreases, the time need to cure or solidify before removal from the mold increases. Generally, a diameter in the range of about 1/4 to 1/8 inch is sufficient to provide a desired manufacturing rate. The stabilizers 45 may additionally help reduce warping or bending of the legs. Unless the sliding surfaces are in one plane, the thickness of a film prepared by the applicator may not be sufficiently even. It is believed that warping may increase over time without the stabilizers. In addition, it is believed that the stabilizers may help increase heat transfer thereby decreasing the time to make the applicator. Advantageously, the stabilizers help provide a gripping surface on the sides of the legs when pulling the applicator across a substrate. It should be appreciated that the draw-down applicator and the draw-down card of the present invention can be useful for applications outside of a paint store environment. For example, they can be useful in laboratories, graphic arts applications, and the like. A preferred material for use as the substrate includes 10 point paper coated one side cast coat paper. One commercially available paper stock is CROMECOTE 2000 sold by Champion Paper. It is preferable to provide the draw-down sample on the side of the paper coated with a high gloss coating and provide written information on the uncoated side. It should be kept in mind, however, that uncoated paper can also be used, including any other substrate which is capable of receiving a coating by the draw-down applicator of the present invention. While the invention has been described in conjunction with specific embodiments thereof, it is evident that different alternatives, modifications, variations, and uses will be apparent to those skilled in the art in view of the foregoing description. Accordingly, the invention is not limited to these embodiments or the use of elements having specific configurations and shapes as presented herein.

A method for preparing draw-down samples of paint using a draw-down applicator is provided. The draw-down applicator comprises a drawing plate having a bottom drawing surface and a bottom fluid delivery surface; a first support or arm having a bottom sliding surface and being rigidly connected to the first drawing plate; and a second support having a bottom sliding surface and being rigidly connected to the drawing plate. The bottom sliding surfaces of said first and second supports form a first plane, and the bottom drawing surface of said drawing plate is in a second plane. The two planes are parallel but not coplanar. Furthermore, the applicator is a non-metallic material. The method includes forming a puddle of paint on a substrate having a substantially smooth surface and drawing the draw-down applicator over the puddle of paint so that the applicator delivers a substantially uniform thickness of the paint over the substrate.

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to an electroabsorption modulator, a modulator laser device and a method for producing an electroabsorption modulator. Semiconductor laser diodes which are used as transmitting elements in optical telecommunications must simultaneously fulfill a plurality of requirements which can, however, be optimized only in dependence on one another. For example, in the case of a direct modulation in a semiconductor laser diode, only a high current density or a high internal light intensity ensures a fast intrinsic modulability, but at the same time parasitic effects such as parasitic resistances, parasitic capacitances and parasitic inductances in the supply leads should be minimized, and the internal heating of the component should be limited. This can be achieved with the aid of an optical modulator driven separately electrically. Specifically in the case of a laser structure in which the resonator fixes the wavelength—for example in the case of a d istributed f eed b ack laser (DFB laser) or a v ertical- c avity s urface- e mitting l aser (VCSEL), the relative displacement of the laser wavelength and the absorption edge with temperature mostly ensures a narrow temperature window in which the modulation principle functions. It is therefore desirable to have a modulator which can be used in a wide spectral and temperature range. Moreover, it is also desirable for the transmission of digital signals likewise to have a digital modulation principle in which the optical modulator can assume only two states, for example absorbing (“off” state) and poorly or non-absorbing (“on” state), and these states cannot be influenced by the preceding signal sequence. If, for example, the active surface of the laser is reduced, a high current density and a fast modulability together with a limited thermal heating of the laser are achieved with small currents through the active surface. At the same time, however, the series resistance grows because of the current constriction. In conjunction with existing non-scalable capacitances at the connecting contacts (pads) and in the driver circuit, this leads to an undesired additional RC limitation of the modulability. An external modulator is normally used, first and foremost, in telecommunications applications. However, this is expensive in the datacom sector and would precisely nullify the advantage of an inexpensive laser diode, for example a vertical emitter. By contrast, because of the required compactness, in the case of integrated modulators use is predominantly made of direct modulation of the imaginary part of the refractive index in so-called electroabsorption modulators. 2. Description of the Related Prior Art Laser diodes with a monolithically integrated electroabsorption modulator are already known from the prior art, for example from [1], [2] or [3]. In this case, for example, the Quantum Confined Stark Effect, shortened below to QCSE, is utilized in order to displace the absorption edge in the modulator and thereby to switch the modulator to and from between the “off” state and the “on” state. With such a modulator it is only the efficiency of the charge carrier removal, that is to say the charge carrier emission from the quantum wells and the drift over the field region, which limits the intrinsic speed by analogy with photodetectors. It is disclosed in [4] in this context that filling effects and changes in the local electric field should be avoided because of their strong effects on the optical properties. A substantial disadvantage of this modulation principle is, however, the limited effect of the displacement of the quantum well band gap or of the fundamental exciton absorption concerned as a function of the applied field. In the case of a typical VCSEL structure, which should be operated uncooled between 0° C. and 85° C., the relative displacement between maximum gain and emission energy is approximately 30 meV. Moreover, a deviation of up to ±10 meV between laser resonance and modulator band gap should also be permitted in order to be able to compensate layer thickness tolerances between the individual components. In order in an appropriate modulator quantum well to adapt only the band gap or fundamental exciton absorption line by the overall amount set forth above in relation to the resonator wavelength, an absorption edge displacement of 50 meV will already need to be achieved via the change in bias. According to [5], the realistically achievable displacement is approximately half as large. The fields required for this purpose of the level of a few 10 5 V/m would lead to dissociation of the excitons, and the modulation characteristic would not be uniform in the overall operating range. In addition, for a given voltage range the large field region in the system limits the length of the intrinsic region and thus the minimization of the capacitance. Moreover, nonlinear effects such as impact ionization are also to be considered. For GaAs, the ionization coefficient for electrons is just 10 4 /cm at 250 kV/cm. Consequently, electroabsorption modulators which use the QCSE can be used without a problem only in temperature-controlled systems with defined detuning of the resonator wavelength on the one hand, and between the gain and absorption spectra of the active regions, on the other hand. By contrast with the QCSE modulator, in the case of a modulator which operates with charge carrier filling, when it is switched into the transparent state, the charge carriers are firstly transported to the quantum well and then captured there. Consequently, in the case of this modulator type both the charge carrier emission process and the charge carrier capture process form the fundamental speed limitations. The charge carrier capture in quantum wells with good charge carrier inclusion proceeds yet more quickly than the charge carrier emission and is of the order of magnitude of 10 −12 in accordance with [6]. Neither capture nor emission times would be a fundamental limitation for targeted modulation frequencies up to 40 GHz, since these can be kept shorter than 5 ps by means of a favorable quantum well design and, in the case of the emission time, by means of correspondingly high fields. However, this holds only as long as the charge carrier recombination which is slower by several orders of magnitude is not used for switching, and as long as the charge carrier transport by means of drift or diffusion is fast enough. In the case of a pin quantum well structure being forwardly polarized, transport on the undoped barriers at low carrier densities essentially only takes place by means of diffusion. A pin quantum well structure is to be understood in this case as a quantum well structure of a strongly doped p-region, a strongly doped n-region and an intrinsic region lying therebetween. The diffusion time for holes is determined in accordance with τ diff =L i 2 /4D h . In the case of an assumed spacing of the quantum well from the p-doped region of L i =100 nm and a diffusion constant at room temperature of D h =kTμ h /q=5 cm 2 /s for Al 0.2 Ga 0.8 As, this results in such a case in a transport time of approximately 5 ps, but this grows quadratically with the diffusion length. Depending on the quantum well design and doping profile, thus, it is either the transport time or the physical capture time which predominates. If the undoped diffusion regions are reduced, the capacitance is increased, however. This has a disadvantageous effect on the modulation rate if the charge carriers need to be removed from the quantum well again not, as in the laser, already by means of stimulated recombination, but only by means of a change in the external voltage. In this case, the space charge capacitance in series with the bulk resistance leads to an RC limitation of the modulation bandwidth. The intrinsic series resistance is determined chiefly by the p-doped lead layer on the basis of the low hole mobility in semiconductor materials. Consequently, it would be desirable to have a concept which permits optimum setting of capacitance, transport times and bulk resistance depending on semiconductor material used, modulated design and parasiticities of the lead and/or drive. Thus, the bulk resistance can be substantially reduced, for example, when exclusively n-doped lead layers are used. Such a modulation principle, which comprises nipin-structures (structures composed of a layer stack of n -doped layer, i ntrinsic layer, p -doped layer, i ntrinsic layer and n-doped layer) and operates chiefly with electron filling into a quantum well from a neighboring n -doped heterobarrier (reservoir), has become known under the designation BRAQWET ( B arrier R eservoir A nd Q uantum- W ell E lectron- T ransfer) (compare [7]). In accordance with the BRAQWET, the so-called Burstein-Moss-effect is used, that is to say the reduction of the absorption by filling only one sort of charge carrier into the quantum well. Since the state density of the conduction band is normally substantially smaller than that of the valence band, the quantum well is filled with electrons. Consequently, degeneracy is achieved as early as with a low charge carrier density of approximately 2×10 18 cm −3 , and absorption saturation in the region of the band edge, on the basis of the Pauli exclusion principle. The advantage is that the absorption profile can be displaced both in frequency by means of the QCSE, and also in amplitude by means of filling. Consequently, an increase in the field leads in both cases to increasing the absorption. The electron transport times are generally negligible. However, the structures have some disadvantages. Because of the need to optimize electron filling, operations should be conducted with sufficiently high diffusion barriers relative to the electron reservoir. In accordance with [8], this in turn limits the electron emission rate upon switching over to maximum absorption. The effective barrier height is lowered with high fields, if appropriate. Furthermore, it is known in accordance with the prior art to render the reservoir barrier continuous, it thereby being possible to shorten the electron emission times virtually at will. However, in principle this is done at the cost of the electron inclusion. However, the pump-probe measurements published in [9] exhibit no worsening in the electrooptical properties. In the case of optical excitation, however, long effective hole emission times were observed in the nanosecond region. The barrier height on the extraction side for holes is very high in BRAQWETs, in order to configure the electron filling efficiently and with a low leakage current. The negative effect of the field shielding of remaining holes is not yet explained in this case. In general, it is either possible for a given voltage shift to maximize the absorption shift into a larger spectral range, or to optimize rate. Furthermore, in the case of unipolar filling the state of transparency cannot be completely achieved, and the absorption shift is still a function of temperature, although the spectral dependence of the absorption shift is already reduced by contrast with pure QCSE modulators. In addition, only a quantum well can be filled efficiently in unipolar fashion per npn region. Consequently, several absorption regions are mostly arranged one above another. In accordance with [7], this multiplies the voltage requirement. During a lengthy “on” state (absorption minimum in the modulator), by contrast, a state of transparency is achieved nevertheless because of the generation of holes on the basis of the non-vanishing absorption. On the one hand, the modulation depth is thereby a function of the bit sequence, while on the other hand the plasma then produced must be removed from the pn junction or the quantum well. This does lead, finally, to an increased space charge capacitance. Consequently, the respective other charge carrier type, which necessarily arises upon absorption, should be efficiently swept out even in the case of a theoretically pure absorber operating in a unipolar fashion. Disclosed in [10] is an optical electroabsorption modulator in which a first upper cladding layer and a second upper cladding layer are provided over an optical absorption layer. Provided between the first upper cladding layer and the second upper cladding layer is a barrier layer which is provided for the purpose of preventing a diffusion of foreign atoms from the second upper cladding layer or thereabove into the first upper cladding layer and the optical absorption layer. A monolithically integrated laser diode modulator with a strongly coupled super-lattice is disclosed in [11]. In this laser diode modulator, the same epitaxial layer, specifically a strongly coupled, combined super-lattice, is used as active layer of the laser diode and as absorbing layer of the modulator. [12] discloses an integrated modulator semiconductor laser device which is produced on a semiconductor wafer by means of selective crystal growth. For this purpose, each chip region on the semiconductor wafer is divided into two semiconductor regions. There is produced on each first semiconductor region a semiconductor laser which can emit laser light, and there is produced on each second semiconductor region a light modulator which can modulate the intensity of the laser light emitted by the semiconductor laser. A semiconductor device with cascade-modulation-doped quantum well heterostructures is disclosed in [13]. In this semiconductor device, known modulation-doped quantum well heterostructures are cascaded in order to increase the rate of functioning without significantly increasing the operating potentials. Moreover, [14] discloses a semiconductor device with polarization-independent stacked heterostructure, which is similar in its design to the semiconductor device known from [13]. BRIEF SUMMARY OF THE INVENTION The invention is therefore based on the problem of specifying an electroabsorption modulator, a modulator laser device and a method for producing an electroabsorption modulator, in the case of which modulator/device the modulator can be used in a wide spectral and temperature range and has fast switching times. The problem is solved by means of an electroabsorption modulator, a modulator laser device and a method for producing an electroabsorption modulator with the aid of the features in accordance with the independent patent claims. An electroabsorption modulator comprises a layer sequence of at least five layers, the layer sequence having sequentially a first layer with excess charge carriers of a first charge carrier type, a second layer without excess charge carriers, a third layer with excess charge carriers of a second charge carrier type, a fourth layer without excess charge carriers, and a fifth layer with excess charge carriers of the first charge carrier type. Arranged between the first layer and the third layer is at least one light absorption layer which can generate charge carriers upon irradiation of light of a specific wavelength. Arranged between the third layer and the fifth layer is at least one storage layer which is set up to store charge carriers. A modulator laser device comprises a semiconductor laser and an electroabsorption modulator. The electroabsorption modulator comprises, for example, a layer sequence of at least five layers, the layer sequence having sequentially a first layer with excess charge carriers of a first charge carrier type, a second layer without excess charge carriers, a third layer with excess charge carriers of a second charge carrier type, a fourth layer without excess charge carriers, and a fifth layer with excess charge carriers of the first charge carrier type. Arranged between the first layer and the third layer is at least one light absorption layer, which can generate charge carriers upon irradiation of light of a specific wavelength. Arranged between the third layer and the fifth layer is at least one storage layer which is set up to store charge carriers. The electroabsorption modulator and the semiconductor laser are arranged in such a way that the electroabsorption modulator can transmit or absorb light emitted by the semiconductor laser. In the case of a method for producing an electroabsorption modulator, a layer sequence of at least five sequential layers is produced on a substrate. Excess charge carriers of a first charge carrier type are introduced into the first layer and into the fifth layer of the layer sequence. Excess charge carriers of a second charge carrier type are introduced into the third layer of the layer sequence. By contrast, no excess charge carriers are introduced into the second layer and into the fourth layer of the layer sequence. Both the first layer and the fifth layer of the layer sequence are electrically coupled to in each case at least one electric connection in order to form an electroabsorption modulator. One advantage of the invention can be seen in that the electro a bsorption modulator is clearly a B ipolar Q uantum R eservoir E lectroabsorption M odulator (BIPQREAM) with an npn or a pnp arrangement. Both electrons and holes (therefore the designation “bipolar”) are filled into the absorbing region of the electroabsorption modulator. This leads to a large modulation range between maximum absorption in the swept-out state, that is to say without charge carrier filling in the absorber region, and virtually vanishing absorption in the filled state, that is to say with charge carrier filling in the absorber region. In this case, the modulation range is largely insensitive to spectral and/or temperature fluctuations. The state of maximum absorption is denoted below as “off” state, and the state of minimum absorption as transparency state or “on” state. A further advantage of the invention is the fact that a quantum reservoir is used for storing the charge carriers. This ensures that the maximum modulation shift is reached quickly, since the charge carriers need not be generated each time by absorption of the laser light. In addition, the finite lifetime in the reservoir quantum films ensures a limitation of the quantity of moving charge carriers, and thus of the effective capacitance. It always blocks one of the two pn junctions, for which reason no external current is generated. The charge carrier quantity is automatically controlled during the transparency states, since the charge carrier density in the absorption regions is held just below the respective transparency density dependent on the laser wavelength, because of the type and number of quantum films. The remaining absorption is just so large that it is possible to compensate unavoidable charge carrier losses, chiefly non-radiating and spontaneous recombination in the absorber quantum films. When a switchover is made into the absorption state, the charge carriers are transferred onto the reservoir region. In the case of long absorption times, a permanent filling of the reservoir quantum films is performed from the photocurrent of the modulator quantum wells, which is fed either by a non-vanishing laser signal or—in the special case of pure Q-switching—by the remaining spontaneous emission of the laser. The number of stored charge carriers is limited because of recombination in the reservoir quantum wells. In order to avoid a modulation efficiency dependent on the bit sequence, the type and number of reservoir quantum films should be selected in such a way that the maximum charge carrier quantity is somewhat greater than the quantity required at least for the modulation, and that the latter can be kept even in the case of long “off” states. Possible excess charge carriers are automatically released again to the rising laser field when a switchover is made to “transparent”. The limitation of the charge carrier quantity in this case limits the maximum effective capacitance. The charge reversal of the quantum wells is performed by means of charge carrier drift and by means of diffusion during filling in the respectively forwardly polarized pn junction. The maximum rate is substantially determined by the combined diffusion and capture time and by the charge carrier emission time. The absorption shift can be adapted within a single npn structure by means of the number of quantum wells. Since the absorption in the case of each switching operation changes between maximum (swept-out absorber quantum wells) and vanishing (filled absorber quantum wells), the absorption shift is not in principle a function of the bit sequence. The only variable dependent on the bit sequence is, as described above, the additional space charge capacitance, on the basis of the charge carrier excess after long absorption states. However, it is bounded above by the lifetime of the charge carriers in the reservoir quantum wells. In the electroabsorption modulator according to the invention, use is made for the first time of a bipolar charge carrier filling in order to achieve the largest possible absorption shift in conjunction with the smallest possible spectral sensitivity. In this case, there is neither a need for a biasing current, nor does a rate-limiting recombination occur. The charge carrier quantity required for switching is provided by an appropriate quantum reservoir, which makes scarcely any contribution to the absorption, and is simultaneously bounded above. This permits a very far reaching digital modulation, in which the two optical states are strongly dependent neither on the signal sequence nor on the level of the input signal. The first layer, the third layer and the fifth layer of the layer sequence of the electroabsorption modulator according to the invention are preferably appropriately doped to generate the respective excess charge carriers. Alternatively, the excess charge carriers can also be generated in the respective layers by means of applying appropriate voltages or electromagnetic fields. In a preferred development of the electroabsorption modulator according to the invention, the light absorption layer and the storage layer each have at least one at least one-dimensional quantum system. For example, a layer with embedded quantum points, a layer with at least one quantum wire or a layer made of at least one quantum film can be used as quantum system. The first layer, the third layer or the fifth layer of the electroabsorption modulator according to the invention, or an arbitrary combination of these layers preferably has/have at least one laterally extended insulating layer with a central opening. On the one hand, this limits the current flow through the layer sequence of the electroabsorption modulator and thus the active modulator region in which the laser light to be modulated overlaps with the modulator region. For this purpose, the first layer and the fifth layer of the layer sequence of the electroabsorption modulator are preferably electrically coupled in each case to an electrode. On the other hand, the insulating layer reduces the overall capacitance of the electroabsorption modulator, since the reactive current fraction in the electroabsorption modulator is lower. In this case, the insulating layer is preferably sheathed by the third layer of the electroabsorption modulator. For example, the insulating layer can then be an oxidized region of the third layer. In a preferred development of the modulator laser device according to the invention, the semiconductor laser and the electroabsorption modulator have at least one common electrically conductive connecting layer. In this case, this can be set up in such a way that a common current flow is avoided both through the electroabsorption modulator and through the semiconductor laser. It is thereby possible to achieve a satisfactory decoupling of the electroabsorption modulator from the semiconductor laser. The electroabsorption modulator and the semiconductor laser are preferably monolithically integrated on a semiconductor substrate in the modulator laser device according to the invention. The modulator laser device is therefore a cost-effective component for the datacom sector up to 40 Gbits, which requires no expensive cooling device. For example, the semiconductor laser can be a vertically emitting laser, the electroabsorption modulator and the semiconductor laser then being arranged vertically above one another in the modulator laser device. Alternatively, an edge-emitting laser can be used as semiconductor laser, the electroabsorption modulator and the semiconductor laser being arranged laterally next to one another. If an edge-emitting laser is used as a semiconductor laser, the latter preferably has a resonator based on Bragg structures. The invention therefore constitutes a temperature-noncritical optical electroabsorption modulator which also operates digitally in a specific embodiment. Exemplary embodiments of the invention are illustrated in the figures and will be explained in more detail below. In this case, like reference symbols designate like components. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a schematic diagram of the energy bands of an electroabsorption modulator in accordance with a first exemplary embodiment of the invention; FIG. 2 shows a schematic diagram of the energy bands of an electroabsorption modulator in accordance with a second exemplary embodiment of the invention; FIG. 3 shows a schematic diagram of the energy bands of an electroabsorption modulator in accordance with a third exemplary embodiment of the invention; FIG. 4 shows an equivalent electric circuit diagram for an electroabsorption modulator in accordance with the second exemplary embodiment; FIG. 5 shows a cross section through a modulator laser device in accordance with a first exemplary embodiment of the invention; FIG. 6 shows a cross section through a modulator laser device in accordance with a second exemplary embodiment of the invention; FIG. 7 shows a top view of a modulator laser device in accordance with a third exemplary embodiment of the invention; and FIG. 8 shows a top view of a modulator laser device in accordance with a fourth exemplary embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a schematic diagram 100 of the energy bands of an electroabsorption modulator in accordance with a first exemplary embodiment of the invention. The diagram 100 of the energy bands illustrates the active modulator region of the electroabsorption modulator in the absorbing (“off”) state. The electroabsorption modulator comprises a layer sequence of a first n-doped outer lead layer 101 , a first undoped, intrinsic intermediate layer which forms the reservoir region 104 , a p-doped middle layer 102 , a second undoped, intrinsic intermediate layer, which forms the absorber region 106 , and a second n-doped outer lead layer 103 . The first n-doped outer lead layer 101 forms a first pn junction together with the middle layer 102 , and the second n-doped outer lead layer 103 forms a second pn junction with the middle layer 102 . The first pn junction is forward-biased, while the second pn junction is reverse-biased. The forward-biased first pn junction therefore constitutes the reservoir region 104 , while the reverse-biased second pn junction constitutes the absorber region 106 . A reservoir quantum film 105 is arranged in the reservoir region 104 , and an absorber quantum film 107 is arranged in the absorber region 106 . Use is made for the middle layer 102 of a material which has a higher band gap than the material for the first or second n-doped outer lead layer 101 , 103 , respectively. Electron leakage currents from the forward-biased first pn junction into the reverse-biased second pn junction are thereby reduced. This clearly means that the middle layer 102 substantially reduces an electron flow from the reservoir region 105 into the absorber region 107 . As long as the electroabsorption modulator is in the absorbing state, incident laser light 108 is converted in the absorber quantum film 107 of the absorber region 106 into charge carrier pairs. The positively charged holes (defect electrons) migrate owing to charge carrier drift into the middle layer 102 and finally fill the reservoir quantum film 105 in the reservoir region 104 by means of diffusion. The quantity of electrons which corresponds to the holes flows off via the second n-doped outer lead layer 103 , and induces a photocurrent between the second n-doped outer lead layer 103 and the first n-doped outer lead layer 101 , when the first n-doped outer lead layer 101 and the second n-doped outer lead layer 103 are coupled to one another by means of an outer electric circuit. The fundamental absorption edge of the absorber quantum film 107 is set in such a way that the incident laser light 108 is efficiently absorbed at all operating temperatures. The band gap of the reservoir quantum film 105 is selected either to be greater or to be smaller than the band gap of the absorber quantum film 107 . If the band gap of the reservoir quantum film 105 is greater than the band gap of the absorber quantum film 107 , a short circuit of the electroabsorption modulator (U(t)=0) leads automatically to the transparent state (“on” state) of the electroabsorption modulator, since all generated charge carriers predominantly remain in the absorber quantum film 107 . If the band gap of the reservoir quantum film 105 is smaller than the band gap of the absorber quantum film 107 , a short circuit of the electroabsorption modulator (U(t)=0) leads to the absorption state (“off” state) of the electroabsorption modulator owing to the separation of the generated charge carriers, as a result of which a non-vanishing outer short circuit photocurrent flows. In this case, the optical filling factor of the reservoir quantum film 105 can be selected to be smaller than for the absorber quantum film 107 , in order to reduce the absorption of the incident laser light 108 in the reservoir quantum film 105 . If the filling factors, that is to say the probabilities for the absorption of a photon of the incident laser light 108 , are similar for the reservoir region 104 and the absorber region 106 , it is also possible to carry out a frequency doubling by means of the electroabsorption modulator, since then both quantum films 105 , 107 operate alternately as reservoir and as absorber. The electroabsorption modulator illustrated by means of the diagram 100 is an npn structure in which electrons are used to switch the absorber region 106 . If, instead of this, recourse is made to a pnp structure, holes are used to switch the absorber region 106 . A schematic diagram 200 of the energy bands of an electroabsorption modulator in accordance with a second exemplary embodiment of the invention is illustrated in FIG. 2 . By contrast with FIG. 1 , apart from the p-doped middle layer 102 , the two n-doped outer lead layers 101 , 103 also have a material with a higher band gap, in order to reduce the hole leakage currents. This is particularly sensible whenever very flat quantum films with a low valence band offset are used as reservoir quantum film 105 and as absorber quantum film 107 . All layer junctions, also termed heterobarriers, are implemented by means of suitably doped variation layers 201 , 202 , 203 and 204 , such that the respective majority charge carriers perceive a negligibly small electric resistance. The variation layers 201 , 202 , 203 , 204 comprise a continuous variation in the doping profile. Furthermore, the variation layers 201 , 202 , 203 , 204 in accordance with this exemplary embodiment of the invention comprise a layer thickness of 9 nm in each case. Furthermore, the diagram 200 shows the use of a selectively oxidizable layer 205 within the middle layer 102 . In the preferred material system Al x In y Ga 1−x−y As 1−m−n Sb m N n for growing on GaAs substrates, such a selectively oxidizable layer 205 usually comprises a very high aluminum content of x>0.8. Alternatively, it is also possible to grow a layer sequence of thin super-lattice layers, of which at least one individual layer should then have a correspondingly high aluminum content. During the production of the selectively oxidizable layer 205 , the selective oxidation is stopped in good time in order no longer to oxidize the active modulator region, which has a substantial overlap with the laser light. A reduction in the effective modulator capacitance is achieved by means of the selectively oxidizable layer 205 , as is illustrated in FIG. 4 . FIG. 3 shows a schematic diagram 300 of the energy bands of an electroabsorption modulator in accordance with a third exemplary embodiment of the invention. The difference between the electroabsorption modulator in accordance with the third exemplary embodiment and the electroabsorption modulator in accordance with the second exemplary embodiment is explained with the aid of the difference between the schematic diagrams 200 and 300 . A selectively oxidizable layer 205 within the middle layer 102 is illustrated in FIG. 2 , while FIG. 3 shows the energy bands of an electroabsorption modulator of the two selectively oxidizable layers 301 , 302 . In each case, one of the two selectively oxidizable layers 301 , 302 is arranged at the edge of each of the two n-doped outer lead layers 101 , 103 . A reduction in the effective modulator capacitance is also achieved by means of the two selectively oxidizable layers 301 , 302 . Because of the reduction in the effective modulator capacitance, it is possible to achieve a simplified electrical operation of the electroabsorption modulator, and thus a faster intrinsic modulation of the electroabsorption modulator. It is possible to achieve an increase in the fraction of the electron filling compared with the hole filling by reducing the spacing of the absorber quantum film 107 from the fourth variation layer 204 . This corresponds to a reduced charge carrier transparency density. By contrast with pure BRAQWETs, however, charge carriers of the respective other polarity (here, therefore holes) from the reservoir quantum film 105 are still used for a complete transparency of the electroabsorption modulator. In the borderline case of an n-doped absorber region 106 , only low charge carrier densities are required, but the level of the absorption of the electroabsorption modulator is then directly dependent on the level of the input voltage U(t), and this leads to an analogue (non-digital) modulation response of the electroabsorption modulator. FIG. 4 shows an equivalent electric circuit diagram 400 for an electroabsorption modulator in accordance with the second exemplary embodiment. An input voltage U(t) is present at the electroabsorption modulator. This is compounded from a bias voltage U bias present at the electroabsorption modulator and an effective modulator voltage U mod , which is generated by the generated charge carriers. Both the capacitance effect of the active modulator region and the capacitance effect of the passive modulator region are taken into account for the overall capacitance of the electroabsorption modulator. The ohmic lead resistance of the active modulator region firstly represents an equivalent resistor R sa . The charge carrier generation in the absorber region 106 causes a photocurrent I ph between the external connections of the electroabsorption modulator, which overcomes an ohmic resistance R p during the charge carrier preparation between absorber region 106 and reservoir region 104 . The reservoir region 104 and the absorber region 106 are symbolized respectively by means of a capacitor C 1a , C 2a . An equivalent resistor R sp represents the ohmic lead resistance of the passive modulator region. The laterally selectively oxidizable layer 205 enclosed by the middle layer 102 is symbolized by means of the capacitors C 1p , C ox and C 2p . The capacitance effect of the active and passive modulator regions C mod,act and C mod,pass , respectively, can now be calculated from the following equations, taking account of the generated charge carrier quantity ΔQ: C mod , act = ( 1 C 1 ⁢ a + 1 C 2 ⁢ a ) - 1 + Δ ⁢   ⁢ Q U mod , ( 1 ) C mod , pass = ( 1 C ox + 1 C 1 ⁢ p + 1 C 2 ⁢ p ) - 1 . ( 2 ) The following condition should be satisfied in order to be able to ensure reliable operation of the electroabsorption modulator: C mod,pass R sp <C mod, act ( R sa +R p ).  (3) The overall capacitance of the electroabsorption modulator C mod is therefore yielded by adding the capacitance effects of the active and the passive modulator regions, which is therefore smaller than the overall capacitance C mod c of a modulator without a selectively oxidized layer 205 : C mod =C mod,act +C mod,pass <C mod c .  (4) The maximum achievable 3 dB cut off frequency f 3dB,int for the current modulation of the electroabsorption modulator is therefore yielded in accordance with f 3 ⁢ dB , int = 1 2 ⁢ π ⁡ ( R sa + R p ) ⁢ C mod , act = f 3 ⁢ dB , int 0 , ( 5 ) and is identical to the maximum achievable 3 dB cut off frequency f 3dB,int 0 without a selectively oxidizable layer 205 . FIG. 5 illustrates a cross section through a modulator laser device 500 in accordance with a first exemplary embodiment of the invention. The modulator laser device 500 is composed of an electroabsorption modulator 200 in accordance with the second exemplary embodiment, and of a surface-emitting semiconductor laser with vertical resonator (VCSEL). In this case, the electroabsorption modulator 200 is monolithically integrated within the rear reflector of the semiconductor laser. In accordance with the present embodiment of the invention, Al x Ga 1−x As is used as basic material for the semiconductor laser and for the electroabsorption modulator 200 . This material can have additional constituents such as, for example, indium or nitrogen for producing the individual layers, and/or be n-doped or p-doped in accordance with the requirements. The modulator laser device 500 firstly has an n-doped substrate 501 with a rear n-contact 502 . A plurality of n-doped resonator Bragg reflectors 503 are applied to the n-doped substrate 501 . The n-doped substrate 501 , the n-contact 502 and the n-doped resonator Bragg reflector 503 together form the first n-doped outer lead layer 101 . The following adjoin the main components of the electroabsorption modulator 200 : the reservoir region 104 with at least one reservoir quantum film 105 , followed by the p-doped middle layer 102 with a selectively oxidized layer 205 for reducing the overall capacitance and the absorber region 106 with at least one absorber quantum film 107 . The absorber quantum film 107 and the reservoir quantum film 105 typically each have a thickness of 7 nm. The absorber region 106 and the reservoir region 104 in each case have a layer thickness of the order of magnitude of 120 nm to 150 nm. The layer thickness of the middle layer 102 is of the order of magnitude of 90 nm. Situated above the absorber region 106 is the second n-doped outer lead layer 103 , which forms the common ground contact of the semiconductor laser and of the electroabsorption modulator, and is provided with suitable n-contacts 504 . In order to reduce electrical crosstalk between the semiconductor laser and the electroabsorption modulator, the layer conductivity of the second n-doped outer lead layer 103 should be sufficiently high. This can be ensured by means of a suitable doping and an adequate thickness. An additional reflector layer 505 between the active zone of the semiconductor laser and the electroabsorption modulator is provided for setting the desired absorption or photon round trip time. This additional reflector layer 505 influences the optical overlap of the laser modes with the absorber quantum film 107 . Adjoining the additional reflector layer 505 is the active laser zone 506 of the semiconductor laser with a laser quantum film 507 and a plurality of p-doped resonator Bragg reflectors 508 with a current aperture 509 , and the laser contacts 510 . The laser contacts 510 are arranged in such a way that the laser light 511 emitted by the semiconductor laser and which is influenced by the integrated electroabsorption modulator 200 can leave the modulator laser device 500 perpendicular to the surface. The semiconductor laser emits laser light at a wavelength of 850 nm. The Bragg resonator of the semiconductor laser has an effective length of 1.8 μm, and the current aperture 509 has a diameter of 6 μm. The current density is of the order of magnitude of 5 kA/cm 2 . The present electroabsorption modulator 200 operates in the range of the loss modulation, which is limited in principle only by the mean photon lifetime in the resonator. This is τ p =2.94 ps in the system presented. The emitted wavelength of the semiconductor laser is a function both of the Bragg resonator and of the active laser zone 506 . It is possible, for example, to set and modulate efficiently all the wavelengths in the range from approximately 700 nm to approximately 1500 nm by means of a suitable mixing ratio of Al x In y Ga 1−x−y As 1−m−n Sb m N n for the active laser zone 506 of the semiconductor laser, and of a similar mixing ratio for the absorber quantum film 107 of the electroabsorption modulator. The modulator laser device 500 can be produced by means of conventional process methods. The current aperture 509 of the semiconductor laser can be produced both by means of ion implantation and also by means of lateral oxidation or an appropriate combination of lateral oxidation with ion implantation. FIG. 6 shows a cross section through a modulator laser device 600 in accordance with a second exemplary embodiment of the invention. The modulator laser device 600 in accordance with the second exemplary embodiment differs from the modulator laser device 500 in accordance with the first exemplary embodiment essentially in that instead of being arranged, as shown in FIG. 5 , below the semiconductor laser the electroabsorption modulator 200 is now arranged above it. Situated over the entire surface on the rear of the substrate is the p-contact 601 , followed by p-doped resonator Bragg reflectors 508 with current aperture 509 and the active laser zone 506 with laser quantum film 507 . Arranged there above are the second n-doped outer lead layer 103 , which is laterally extended and serves as common ground layer for the electroabsorption modulator 200 and the semiconductor laser, with the n-contacts 504 , and a coupling reflector 602 for optically coupling the electroabsorption modulator 200 to the semiconductor laser. These are covered by the modulator region comprised of absorber region 106 with absorber quantum film 107 , middle layer 102 with selectively oxidizable layer 205 and reservoir region 104 with reservoir quantum film 105 . The “hot” modulator electrode is formed by the n-doped resonator Bragg reflectors 503 and the metal contact 603 , which together implement the first n-doped outer lead layer 101 . By comparison with the modulator laser device 500 in accordance with the first exemplary embodiment, the modulator laser device 600 in accordance with the second exemplary embodiment has, inter alia, the advantage of a smaller modulator area, as a result of which the capacitances of the electroabsorption modulator are reduced. However, the production of the semiconductor laser, in particular the current aperture 509 , is more complicated because of the required uniformity of the semiconductor laser. The current aperture 509 can, in turn, be produced both by means of oxidation, by means of ion implantation, by means of multiple epitaxy with buried tunnel contact, or by means of a combination of these production methods. A particular feature of the modulator laser device 600 in accordance with the second exemplary embodiment is that it is also suitable in strip geometry for edge-emitting semiconductor lasers with monolithically integrated electroabsorption modulator. In this case, suitable wave guiding layers then replace the resonator Bragg reflector 503 , 508 and the additional reflector layer 505 . Depending on the composition of the wave guiding layers, it is possible to select either a coupled waveguide structure or a common waveguide structure for absorber and laser. FIG. 7 shows a top view of a modulator laser device 700 in accordance with a third exemplary embodiment of the invention. The modulator laser device 700 combines an edge-emitting semiconductor laser with a monolithically integrated electroabsorption modulator. A coupled waveguide structure for the semiconductor laser and the electroabsorption modulator is preferred in this case. The waveguidance of the semiconductor laser is essentially performed via the additional reflector layer 505 , which can be influenced technologically by the type of the resonator grating 701 . The emission of the laser light generated by the semiconductor laser and influenced by means of the electroabsorption modulator takes place by means of the emission opening 702 on the coupled waveguide structure. Given a suitable selection of the waveguide coupling, the position of the resonator grating 701 and its length L G , the overall length L of the modulator laser device 700 and of the modulator length L M , it is also possible to implement semiconductor lasers with a DBR-type or DFB-type laser structure. The decoupling between the electroabsorption modulator and the semiconductor laser can then be optimized by means of the resonator grating for the waves returning from the electroabsorption modulator. A selective oxidation in the lower p-doped resonator Bragg reflector 508 is preferably used to define a current aperture and simultaneous lateral waveguidance for the semiconductor laser. A top view of a modulator laser device 800 in accordance with a fourth exemplary embodiment of the invention is illustrated in FIG. 8 . By contrast with the modulator laser device 700 in accordance with the third exemplary embodiment, in the modulator laser device 800 in accordance with the fourth exemplary embodiment the electroabsorption modulator 200 comprises two sections which are electrically decoupled from one another, but strongly coupled optically to one another. In this case, a common waveguide is used for the semiconductor laser and the electroabsorption modulator 200 , and its optical disturbance on the section L C in the region of the electric decoupling should be as small as possible. The electric decoupling can be performed, for example, by means of deep etching. The optical coupling can be optimized, for example, by means of antireflection coating or by means of filling in material with a sufficiently high refractive index at the disturbed site. The optical overlap of the absorber region 106 can be reduced by means of an asymmetric waveguide design. However, the modulator length L M should then be correspondingly enlarged. Furthermore, the waveguidance within the modulator should be rendered sufficiently strong so that the intensity in the middle layer 102 and in the reservoir region 104 already drops strongly, and thus the disturbance becomes negligibly small over the short section L C . An optional second modulator contact 801 can be provided, for example, with a defined potential in order to switch the passive region, lying there below, of the electroabsorption modulator 200 to be transparent in a defined fashion so that the outcoupling efficiency of the semiconductor laser is not reduced by parasitic absorption. The following publications are quoted in this document: [1] P. Steinmann, B. Borchert, B. Stegmutller: “Improved Behaviour of Monolithically Integrated Laser/Modulator by Modified Identical Active Layer Structure”, IEEE Photonics Technol. Lett., Vol. 9, No. 12, pp. 1561-1563, 1997 [2] S. F. Lim, J. A. Hudgings, L. P. Chen, G. S. Li, W. Yuen, K. Y. Lau, C. J. Chang-Hasnain; “Modulation of a Vertical-Cavity Surface-Emitting Laser using an Intracavity Quantum-Well Absorber”, IEEE Photonics Technol. Lett., Vol. 10, No. 3, pp. 319-321, 1998 [3] J. A. Hudgings, R. J. Stone, C. H. Chang: “Dynamic Behavior and Applications of a Three-Contact Vertical Cavity Surface-Emitting Laser”, IEEE J. of sel. Topics in Quantum Electronics, Vol. 5, No. 3, pp. 512-519, 1999 [4] P. J. Bradley, C. Rigo, A. Stano: “Carrier Induced Transient Electric Fields in a p-i-n InP-InGaAs Multiple-Quantum-Well Modulator”, IEEE J. of Quantum Electronics, Vol. 32, No. 1, pp. 43-52, 1996 [5] K. W. Jelley, R. W. H. Engelmann, K. Alavi, H. Lee: “Well Size Related Limitations on Maximum Electroabsorption in GaAs/AlGaAs Multiple Quantum Well Structures”, Appl. Phys. Lett., Vol. 55, No. 1, pp. 70-72, 1989 [6] M. Preisel, J. Mork: “Phonon-Mediated Carrier Capture in Quantum Well Lasers”, J. Appl. Phys., Vol. 76, No. 3, pp. 1691-1696, 1994 [7] M. Wegener, J. E. Zucker, T. Y. Chang, N. J. Sauer, K. L. Jones, D. S. Chemla: “Absorption and Refraction Spectroscopy of a Tunable-Electron-Density Quantum-Well and Reservoir Structure”, Phys. Rev. B., Vol. 41, No. 5, pp. 3097-3104, 1990 [8] J. Wang, J. P. Leburton, J. L. Educato, J. E. Zucker: “Speed Response Analysis of an Electron-Transfer Multiple-Quantum-Well Waveguide Modulator”, J. Appl. Phys., Vol. 73, No. 9, pp. 4669-4679, 1993 [9] N. Agrawal, M. Wegener: “Ultrafast Graded-Gap Electron Transfer Optical Modulator Structure”, Appl. Phys. Lett., Vol. 65, No. 6, pp. 685-687, 1994 [10] EP 1 069 456 A2 [11] DE 692 03 998 T2 [12] DE 44 29 772 C2 [13] DE 690 15 228 T2 [14] EP 0 599 826 B1

Electroabsorption modulator ( 100 ) having a layer sequence of at least five sequential layers, having at least one light absorption layer ( 106 ) which is arranged between the first layer ( 101 ) and the third layer ( 102 ) and is set up to generate charge carriers upon irradiation of light ( 108 ) of a specific wavelength, and having at least one storage layer ( 104 ) which is arranged between the third layer ( 102 ) and the fifth layer ( 103 ) and is set up to store charge carriers.

FIELD OF THE INVENTION This invention relates generally to the secure delivery and receipt of data using public key cryptography (PKC); more particularly, to the secure delivery and receipt of encrypted messages and Secure Multipurpose Internet Mail Extension (S/MIME) encrypted messages where the sender does not possess the credentials of the recipient either because the recipient is not enrolled in a Public Key Infrastructure (PKI) or the recipient has not provided their public key to the sender. BACKGROUND OF THE INVENTION Several discoveries have been made to address the need for securing messages between a sender and receiver. One such discovery being the Diffie-Hellman algorithm and the Rivest Shamir Adleman public key crypto system discovered in the mid 1970s. The significance of these discoveries is that they have become standards on which present encryption systems are built. The Diffie-Hellman algorithm is especially suited to secure real time communications. The Diffie-Hellman algorithm requires the participation of both the sender and receiver. To execute, the two participants choose two numbers which in turn are used in conjunction with secret numbers which are correspondingly secret to each of the two participants to derive a third number which is exchanged between the two participants. The exchanged numbers are then used in a process to encrypt the messages between the two participants and then to decrypt the messages. This method therefore requires the active participation of the recipient in order to send a secure message. As a consequence, the system is best suited for only two participants in the message, and is not suited for multiple participants. Furthermore, although the system secures the confidentiality of the message satisfactorily it does not ensure the authenticity of the message or the sender in terms of what is known as a “digital signature”. As such, the Diffie-Hellman algorithm is predominantly used to secure the real time communication sessions between a sender and a receiver over a network. The Rivest Shamir Adleman (RSA) public key crypto system, while inspired by the Diffie-Helman algorithm, developed a method that 1.) does not require the active participation of the recipient, 2.) allows for more than two participants in a message, and 3.) established a framework to provide authenticity of both the sender and of the message itself in addition to securing the message between the sender and the recipient(s). Securing messages between senders and recipients can be accomplished in an infinite number of ways. To secure email, arguably the most widely deployed application on the Internet, the S/MIME standard was developed in the late 1990s. While there are proprietary methods for securing email messages such as those developed by organizations such as PGP, Hushmail, Zixit, Ziplip etc., S/MIME has become the dominant world standard to secure email communications. The S/MIME protocol was established by RSA Data Security and other software vendors in 1995. The goal of S/MIME was to provide message integrity, authentication, non-repudiation and privacy of email messages through the use of Public Key Infrastructure (“PKI”) encryption and digital signature technologies. Email applications that support S/MIME assure that third parties, such as network administrators and ISPs, cannot intercept, read or alter messages. S/MIME functions primarily by building security on top of the common MIME (Multipurpose Internet Mail Extension) protocol, which defines the manner in which an electronic message is organized, as well as the manner in which the electronic message is supported by most email applications. Currently, the most popular version of S/MIME is V3 (version three), which was introduced in July, 1999. Further information on S/MIME standardization and related documents can be found on the Internet Mail Consortium web site and the IETF S/MIME working group “web site.” The S/MIME V3 Standard consists generally of the following protocols: Cryptographic Message Syntax (RFC 2630); S/MIME Version 3 Message Specification (RFC 2633); and S/MIME Version 3 Certificate Handling (RFC 2632). S/MIME and similar secure message systems rely on PKC to invoke security. With S/MIME security, a MIME message is secured by digitally signing the message which is conducted by encrypting a message digest hash with the private key of the sender. This is what is known as a digital signature. Optionally, the message content with the digital signature is encrypted using the public key of the recipient. The encrypted message and digital signature comprise the S/MIME email message that is then sent to the recipient. Upon receiving the message, the recipient's private key is used to decrypt the message. The recipient re-computes the message digest hash from the decrypted message and uses the public key of the sender to decrypt the original message digest hash (the digital signature) and compares the two hashes. If the two hashes are the same, the recipient has validation of the authenticity of the sender and of the integrity of the message. Consequently, S/MIME and similar secure message systems generally require that both the sender and the recipient(s) be enrolled in a PKC system and that the public keys of each be accessible in order for the message to be secured and for the sender and message to be authenticated. As such, if the recipient is not enrolled in a PKI, or the sender does not have access to the recipient's(s') key(s), the sender will not be able to send a secure message to the recipient(s). What is needed therefore is a system, computer program and method for delivering encrypted messages to recipient(s) where the sender does not possess the credentials of the recipient(s) or some subset thereof. What is further needed is the aforesaid system, computer program and method that can access or generate message encryption keys, which can be used by the sender to ensure the privacy of the message for the recipient. What is still further needed is the aforesaid system, computer program and method that is easily deployed in either a browser or on a client application provided at the network-connected devices themselves. What is also needed is a web-based or client based system, computer program and method whereby the encryption persists throughout the communication and storage of data. What is also needed is a web-based or client-based system, computer program and method whereby the message decryption key is stored securely and accessed securely by the recipient in order to decrypt the message. SUMMARY OF THE INVENTION The system, method and computer program of the present invention enables users to create and send encrypted email or other encrypted messages either through a browser or through client software without the need to have the certificate(s) or public key(s) of the recipient(s). From a sender usability perspective this eliminates the sender's inability to send secure messages when a recipient is not enrolled in a PKI and therefore does not possess a PKI certificate or when the recipient's certificate is not in the possession of the sender. In another aspect of the present invention permits recipients to access private PKC based encrypted messages without the need to be enrolled in a PKI. In another aspect of the present invention permits recipients to access PKC keys over the Internet from any network-connected device. This eliminates the need for location specific private key and digital certificate storage. BRIEF DESCRIPTION OF THE DRAWINGS A detailed description of the preferred embodiment(s) is(are) provided herein below by way of example only and with reference to the following drawings, in which: FIG. 1 a is a schematic System Architectural Component Diagram of the secure message system of the present invention. FIG. 1 b is a program resource chart illustrating the resources of the application of the present invention, in one embodiment thereof. FIG. 1 c is a program resource chart illustrating the resources of the application of the present invention, in another embedment thereof. FIG. 2 a is a flow chart that depicts the steps in creating, signing, and encrypting a secure message and the generation of security keys for non-enrolled recipients using browser based messaging, in accordance with one aspect of the method of the present invention. FIG. 2 b is a flow chart that depicts the steps in creating, signing, and encrypting a message and the generation of security keys for non-enrolled recipients using client based messaging, in accordance with another aspect of the method of the present invention. FIG. 3 a is a flow chart that depicts the steps for receiving, verifying and decrypting an encrypted message by user who is not enrolled in a PKI using a browser. FIG. 3 b is a flow chart that depicts the steps for receiving, verifying and decrypting an encrypted message by users who are not enrolled in a PKI using a client. FIG. 4 depicts a possible user interface for creating a shared secret to secure a message. FIG. 5 depicts a possible user interface for responding to a challenge question to provide a shared secret FIG. 6 is a flow chart that depicts the steps in signing and encrypting messages in connection with the various components of a PKI infrastructure. FIG. 7 a is a flow chart that depicts the steps in creating, signing, and encrypting a message for non-enrolled recipients using client based messaging and a trusted intermediary. FIG. 7 b is a flow chart that depicts the steps for retrieving and verifying an encrypted message by user who is not enrolled in a PKI using a browser or client and a trusted intermediary. In the drawings, preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood that the description and drawings are only for the purpose of illustration and as an aid to understanding, and are not intended as a definition of the limits of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As illustrated in FIG. 1 , at least one known network-connected device 10 is provided. Network-connected devices 10 may consist of a number of digital devices that provide connectivity to a network of computers. For example, the network-connected device 10 may consist of a known personal computer or a known WAP device, cell phone, PDA or the like. The network-connected device 10 is connected to the Internet 12 in a manner that is known. Specifically in relation to FIG. 1 , the connection of a network-connected device 10 that is a known WAP device to the Internet is illustrated, whereby a known WAP to WEB gateway 107 is provided, in a manner that is also known. Also as shown in FIG. 1 a , each of the network-connected devices 10 may include a known computerized device, which includes a browser 20 and/or client application 40 . The browser can be a standard Internet based browser, such as Netscape's NAVIGATOR.™. or Microsoft's INTERNET EXPLORER.™. or a known mini browser for wireless devices such as cell phones or PDM. Client application 40 can be a known email program such as Microsoft's OUTLOOK.™., OUTLOOK EXPRESS.™., LOTUS NOTES.™., Novell's GROUPWISE.TM., EUDORA.™ or another known email program for wireless devices such as cell phones or PDAs, including those commonly bundled in such devices as part of the devices' operating system or is distributed as a separate component. The client application 40 can also be a custom client used to create secure messages. Each of the network-connected devices 10 also includes the application 22 of the present invention, which consists of the computer program of the present invention. Certain attributes of this application 22 , in particular the manner in which it permits Public Key Cryptography (PKC) enabled communications over wired and wireless networks is disclosed in U.S. Pat. No. 6,678,821 issued to Echoworx Corporation and the Co-Pending patent application Ser. Nos. 10/178,224 and 10/379,528 (the “patent” or the “Co-Pending patent applications”, as applicable). As particularized below, the application 22 includes a PKC utility (not shown). In one particular embodiment of the application 22 , illustrated in FIG. 1 b , the application 22 consists of a specialized browser extension 309 or plug-in. Specifically in this particular embodiment of the invention, the application 22 and the browser 20 inter-operate by means of, for example, customized HTML tags. As opposed to using an intermediate host server, or a relatively large computer program (as is the case with prior art technologies), application 22 preferably provides the necessary resources to enable the network-connected device 10 , as particularized below, to function with any third party PKI system, including for example, ENTRUST™, MICROSOFT™, BALTIMORE™, RSA™ and so forth. It should also be understood that the functions of the application 22 described herein can also be provided as an “ACTIVE X OBJECT” in a manner that is known, or integrated directly into a browser. In another embodiment of application 22 , illustrated in FIG. 1 c , the application 22 consists of a client extension 409 or plug-in is provided in a manner that is known. Specifically, the application 22 and the client application 40 inter-operate by means of, for example, customized programming specific to the client application 40 . As opposed to using an intermediate host server, or a relatively large computer program (as is the case with prior art technologies), application 22 (in this particular embodiment of the invention also) preferably provides the necessary resources on the network-connected device 10 , as particularized below, to function with any third party PKI system, including for example, ENTRUST™, MICROSOFT™, BALTIMORE™, RSA™ and so forth. It should also be understood that the functions of application 22 described herein can also be integrated directly into the client application 40 . Application 22 functions as a cryptographic utility, provided in the manner described in the patent and Co-Pending patent applications, such that the application 22 is adapted to perform at the network-connected device 10 one or more of a series of cryptographic operations, including but not limited to: Digital signature of data in S/MIME format; Encryption of data in S/MIME format; Digital signature of data in form fields; Encryption of data in form fields; Decryption of data in form fields; Verification of signature of data in form fields; Digital signature and encryption of data in form fields; Verification of Digital signature and decryption of data in form fields; Digital signature of full pages; Verification of digital signature of full pages; Encryption of full pages; Decryption of full pages; and File attachment encryption and signing. Specifically, application 22 includes a Crypto Library 300 , provided in a manner that is known. In one particular embodiment of the present invention, the application 22 also includes a User Certificate and Private Key 302 which contains the cryptographic data required to encrypt and/or digitally sign data included in data communications (including email) contemplated by the present invention. For example, in one particular implementation of the present invention, namely one whereby Microsoft software provides the Security Services 312 , the .PFX or DER (Distinguished encoding rules ASN.1) encoded X509 certificate files required to authenticate the sender, or encrypt data for the recipient, are downloaded to the network-connected device 10 or are generated by the network-connected device 10 . The .PFX file is an encrypted file that is used to access the user credentials and private key required to process cryptographic operations. The PFX file is formatted based on the PKCS12 standard. The DER encoded X509 certificate file provides the public key and certificates of the recipient. Security Services 312 should be understood as a general term describing a known PKI infrastructure. PKI infrastructures can vary as to the particulars of their architecture, or their hardware or software components. Typically, however, a PKI infrastructure consists of the components illustrated in FIG. 1 a : a Certificate Authority for issuing and certifying certificates for enrolled users; a Lightweight Directory Access Protocol (or “LDAP”) for storing the public key and certificates of enrolled users; and a Certificate Revocation List (or “CRL”) for revoking certificates. In another aspect of Security Services 12 also illustrated in FIG. 1 a , a Roaming Key Server (or “RKS”) is used for storing private keys of enrolled users. As stated earlier, application 22 of the present invention includes a PKC extension, and specifically a browser extension 309 or the email client extension 409 described below. The PKC extension permits the encryption and decryption of data communications (including email) in a browser or email client, as particularized herein. This has the advantage of broad-based deployment as browser technology and email software is commonplace. This also has the advantage of deployment across wireless and wired networks as the application 22 of the present invention, including the browser or client extension, can be associated with a web browser or a WAP browser, as shown in FIG. 1 a . In addition, the invention disclosed herein requires only a browser or email client and the associated application 22 at each network-connected device 10 rather than a relatively thick client at each network-connected device 10 which reduces the resources required at each such device to provide PKI functionality. Also, as further explained below, in accordance with the present invention, secure encrypted communications are possible without the need to possess the certificates and public key of the recipients, resources usually required to send fully encrypted messages such as S/MIME messages on the network-connected device 10 . Each of the browser extension 309 and the email client extension 409 is generally reduced to code in a manner known by a skilled programmer. However, it is desirable for the browser extension 309 or client extension 409 of the present invention to have a number of attributes. First, as a result of the method of the present invention detailed below, it is desirable that the browser extension 304 and client extension 409 be able to generate a public key pair and to secure the private key based on a secret that is shared between the sender and the recipient such that the password is used to encrypt the private key. Second, the key generation, security, and the encryption and decryption of data described herein involve a potential security risk if the browser extension 309 or client extension 409 is not designed properly. Specifically, it is necessary to ensure that browser memory is (in the case of the browser extension 309 ) utilized in the course of the cryptographic operations such that security is not compromised. In one particular embodiment of the present invention, this is achieved by using the “TEMP” memory space of the browser 20 or client application 40 , in a manner known by a skilled programmer. Third, the browser extension 309 or client extension 409 further includes a CLEANUP ROUTINE or equivalent provided in a manner that is known that eliminates any remnants from the memory associated with the browser, email client, or otherwise with the network-connected device 10 , of either the message, the user credential or private key that is part of the User Certificate and Private Key Store 302 , in order to maintain confidentiality. Specifically, for example in relation to the browser extension 309 , the browser extension 309 is configured such that it will not store a copy of the email in the browser cache. In addition, the browser extension 309 or client extension 409 will delete any copies of any attachments associated with a secure message. As stated earlier, the present invention also contemplates that the browser extension 309 or client extension 409 provides means to establish a shared secret that will be used by the browser extension 309 or the client extension 409 to encrypt the private key corresponding to the public key that is used to encrypt the message or to authenticate a non-enrolled recipient to a trusted intermediary. This particular aspect of the present invention is illustrated in FIGS. 4 and 5 . In addition, the present invention contemplates that the browser extension 309 and the client extension 409 facilitate the notification and delivery of secure messages to a recipient not enrolled in a PKI. More particularly, the browser extension 309 or the client extension 409 is adapted to permit the non-enrolled recipient to respond to a request for a shared secret which upon successful provision thereof releases the private key or authenticate the non-enrolled recipient (illustrated in FIG. 1 a ) to a trusted intermediary in order to decrypt and view the secure message. Also connected to the Internet 12 , is a web server 106 that is provided using known hardware and software utilities so as to enable provisioning of the network-connected device 10 , in a manner that is known. The web server 106 includes a web application 16 . The web application 16 is adapted to execute the operations, including PKI operations, referenced below. The system, computer program and method of the present invention are directed to: 1. Creating, encrypting and delivering secured messages including S/MIME compliant email messages to an email server or a message storage/database server; 2. Retrieving and deciphering secured messages, including S/MIME compliant email messages, from an email server or a message storage/database server; and 3. Creating, securing and delivering recipient data and private key(s) to a secure storage server. In order to achieve the foregoing, the system, computer program and method of the present invention rely on aspects of the patent and the Co-Pending patent applications for engaging in PKI enabled transactions. Specifically, email messages are created and delivered in accordance with the present invention in a manner that is analogous with the “POSTING DATA ON A SECURE BASIS” and “SECURE DELIVERY OF S/MIME ENCRYPTED DATA” described in the Co-Pending patent applications. An email message is retrieved and deciphered in the manner described under the heading “RETRIEVING OF DATA ON A SECURE BASIS” and the “SECURE RECEIPT OF S/MIME ENCRYPTED DATA” also described in the Co-Pending patent Applications. As illustrated in FIG. 1 a , one aspect of the system of the present invention also includes a known email server or message server 306 . The email server or message server 306 sends and receives emails in a manner that is well known. The email server or message server 306 is provided by known hardware and software utilities. Also as illustrated in FIG. 1 a , one aspect of the system of the present invention includes an email protocol translator 308 . The email protocol translator 308 is a known utility which permits the web server 106 and the email server or message server 306 to communicate by translating messages sent by the web server 106 to the particular email protocol understood by the email server or message server 306 such as for example POP3 or IMAP4. Also as illustrated in FIG. 1 a , another aspect of the system of the present invention includes a known message storage/database server 315 . The message storage/database server 315 stores and delivers user credentials and secure messages in a manner that is well known. The message storage/database server 315 is also provided by known hardware and software utilities. The web server 106 , the web application 16 , and the email protocol translator 308 are used to support browser-based encryption and/or decryption of S/MIME messages in the browser as described in the Co-Pending patent applications. The roaming key server 310 is used to store and provision private keys to enrolled users (supporting user mobility) and private message keys for non-enrolled users for the encryption and/or decryption of non-enrolled users for the encryption and/or decryption of S/MIME messages in the browser as described in the Co-Pending patent applications. Normally, private keys are stored on users' desktop computers for use with email client software. However, browser based email allows the user to send or retrieve email from any device with a standard browser. The roaming key server 310 stores and provisions private message keys for use by non-enrolled recipients for decrypting secure messages (as particularized below). In one particular embodiment of the invention, the email server 306 or the message storage/database server 315 is used to store encrypted messages for non-enrolled recipients. In either case, the message storage/database server 315 can be used to store the shared secret for authenticating non-enrolled recipients. The trusted intermediary 316 cooperates with the web server 106 and the web application 16 to authenticate non-enrolled recipients, and in one embodiment of the present invention, upon provision by the recipient of the correct shared secret, decrypt the message and securely deliver the message to the non-enrolled recipient's browser. The Certificate Authority that is part of the Security Services 312 , in one particular embodiment of the present invention, is used to generate “message keys” for non-enrolled recipients. The Directory 314 illustrated in FIG. 1 a , which is part of the Certificate Authority, is used to store public keys of enrolled recipients and to search for the recipient's public keys for encrypting messages. Browser Based Creating, Signing, Encrypting and Sending Messages with Private Key Generation for Non Enrolled Recipients FIG. 2 a illustrates browser based creation and delivery of secure messages for recipients who are not enrolled in a PKI in accordance with the present invention. A user associated with a network-connected device 10 who desires to create and send an email on a secure basis (the “Sender”) requests a page on the web server 106 using the browser 20 loaded on the network-connected device 10 . The web server 106 , and specifically in co-operation with the web application 16 loaded on the web server 106 , responds to the network-connected device 10 by presenting a web page that is a web form requesting that the user associated with the network-device 10 provide authentication in order to gain access to the web application 16 , and specifically a secure message application (not shown) that is included in the web application 16 . The Sender supplies information in the authentication form fields (such as username and password) on the web page and concludes with submitting the form, typically by pressing a ‘SUBMIT’ button or equivalent. The authentication credentials are passed to the web server 106 . The web server 106 in turn delivers the authentication credentials to the email server or message server 306 via the email protocol translator 308 in one embodiment of the application or authenticates the user credentials from the message storage/database server 315 in alternate embodiment of the application. Specifically in accordance with the aspect of the present invention whereby the roaming key server 310 is used to access the User Certificate and Private Key by means of the User Certificate and Private Key Store 302 , the web server 106 also transfers the user credentials to the roaming key server 310 . The email server 306 or message storage/database server 315 authenticates the Sender and then passes back, through the email protocol translator 308 , message waiting lists and other pertinent information about the Sender's email account to the web server 106 for display in the Sender's browser 20 and establishes an email session typically using a cookie, in a manner that is known. The web server 106 authenticates the Sender for the message storage/database server 315 and then passes back message waiting lists and other pertinent information about the Sender's account to the web server 106 for display in the Sender's browser 20 and establishes a session typically using a cookie, in a manner that is known. Again, in accordance with the aspect of the present invention utilizing the roaming key server 310 , the roaming key server 310 authenticates the Sender and transmits the Sender's private key and certificate through the web server 106 to the browser extension 309 . In accordance with the aspect of the present invention whereby the User Certificate and Private Key Store 302 resides on the network-connected device 10 , the private key and certificate is accessed by the browser extension 309 . The Sender prepares a message by completing the appropriate fields of a web form referred to, including for example the message subject, body and intended recipient's fields. In one particular embodiment of the present invention, the application 22 also provides the recipients' shared secret(s). The Security Services 312 is contacted whereby the recipient's(s') public keys and certificates are verified and retrieved from the associated directory 314 or from the sender address book stored on the message storage/database server 315 . In the event that the recipient(s) public key(s) and certificate(s) cannot be retrieved from either “publicly accessible” location, application 22 of the present invention is invoked to create a shared secret and generate a PKC key pair by application 22 to secure the message for non-enrolled recipients. It should be understood that the present invention refers in various places to “non-enrolled recipients”. What is meant is that the sender does not possess, or have access to, the PKI credentials of the recipient, whether the recipient has been enrolled in a PKI or not. In other words, “non-enrolled recipients” also means “non-credentialed recipients”. The private key(s) of the key pair is encrypted in a manner that is well known using the shared secret(s) as the pass phrase which is secured in a manner which is as known. The encrypted private key(s) for non enrolled recipients is(are) stored on the message storage/database server 315 along with recipient information including the shared secret question which the recipient must answer FIG. 5 . Private key(s) storage is not limited to the message storage/database server 315 and could use the roaming key server 310 or email server or message server 306 as alternate locations for private key storage. The message form data is passed to the application 22 , including the browser extension 309 , for signing and encrypting the message and any attachments using the private key of the Sender and the public key(s) of the recipient(s), and in one embodiment of the invention to form an S/MIME compliant email message. The message is returned to the browser 20 and sent from the browser 20 to the web server 106 , and using the email protocol translator 308 to the email server or message server 306 for forwarding to the identified recipients in one embodiment. In another embodiment of the present invention the secured message for non-enrolled recipients is stored to the message storage/database server 315 and an email advisory is generated by the web application 16 and sent to the non-enrolled recipients advising of the secure message waiting and providing instructions on how to retrieve the secure message. Client Based Creating, Signing, Encrypting and Sending Messages with Private Key Generation for Non Enrolled Recipients FIG. 2 a illustrates client based creation and delivery of secure messages for recipients who are not enrolled in a PKI in accordance with the present invention. A user associated with a network-connected device 10 who desires to create and send a message on a secure basis (the “Sender”) invokes the client application 40 (as stated earlier, consisting of a known communication utility such as an email program) loaded on the network-connected device 10 . The Sender supplies authentication information (such as a username and password) and concludes with submitting the form, typically by pressing a ‘SUBMIT’ button or equivalent. Often email client programs are set up such that user authentication is configured in the email client program to automate the authentication process such that it does not require user intervention. The authentication credentials are passed to the email server or message server 306 . The email server or message server 306 authenticates the Sender and then passes back message waiting lists and other pertinent information about the Sender's email account for display in the Sender's client application 40 in a manner that is known. The Sender prepares a message by completing the appropriate fields of the email message form referred to, including for example the message subject, body and intended recipient(s) fields. Security Services 312 is contacted whereby the recipient's(s') public keys and certificates are verified and retrieved from the associated directory 314 or from the sender's address book stored on the communication utility consisting of the email client program 40 . In the event that the recipient(s) public key(s) and certificate(s) cannot be retrieved from either location, application 22 of the present invention is invoked to create a shared secret as illustrated in FIGS. 4 and 5 to generate a PKC key pair to secure the message for non-enrolled recipients. The private key(s) of the key pair are encrypted in a manner that is well known using the shared secret(s) as the pass phrase. The encrypted private key(s) for non enrolled recipients is (are) stored on the message storage/database server 315 along with recipient information including the shared secret question which the recipient must answer as illustrated in FIG. 5 . Private key(s) storage is not limited to the message storage/database server 315 and could use the Roaming Key Server 310 or the email server or message server 306 as alternate locations for private key storage. The message form data is passed to the application 22 , including the email client extension 409 , for signing and encrypting the message and any attachments using the private key of the Sender and the public key(s) of the Recipient(s), and in one embodiment of the invention to form an S/MIME compliant email message. The message is sent from the client to the email server or message server 306 for forwarding to the identified recipients in one embodiment. In another embodiment of the present invention the secured message for non-enrolled recipients is stored to the message storage/database server 315 and an email advisory is generated by the web application 16 and sent to the non-enrolled recipients advising of the secure message waiting and providing instructions on how to retrieve same. Browser Based Retrieving and Decrypting an Encrypted Message from an Email or Message by Non-enrolled Recipients FIG. 3 a illustrates browser based receipt, verification, decryption and display of an encrypted message from an email server or message server 306 or message storage/database server 315 in accordance with the present invention. A non-enrolled user associated with a network-connected device 10 who desires to display an encrypted message or S/MIME email that they have received on a secure basis (the “Recipient”) requests a page from the web application 16 using the browser 20 loaded on the network-connected device 10 . The web application 16 detects if the browser extension 309 is available on the network-connected device 10 . If the browser extension 309 is not available, the web application 16 automatically downloads and installs the browser extension 309 . When the browser extension 309 is available on the network-connected device 10 the recipient's authentication credentials are passed to the browser extension 309 in accordance with the aspect of the present invention whereby message storage/database server 315 or in another embodiment, the roaming key server 310 is used to store the non-enrolled User's Private Key Store 302 which then downloads a copy of the encrypted private key to the browser extension 309 , and for non-enrolled users the question associated with the shared secret pass phrase. The browser extension 309 requests the non-enrolled Recipient to provide authentication and for an answer to the shared secret question, in order to decrypt and display the encrypted message or S/MIME email message. The Recipient supplies password or shared secret information in response to the authentication request ( FIG. 5 ) to the browser extension 309 and concludes with submitting the form, typically by pressing a ‘SUBMIT’ button or equivalent. The authentication credentials are passed to the browser extension 309 in accordance with this aspect of the present invention. The application 22 authenticates against its User Certificate and Private Key Store 302 and if the provided pass phrase is correct, the private key is released to the browser extension 309 component thereof where upon the message signature can be verified and the message decrypted for display in the Recipient's browser 20 . Client Based Creating, Signing, Encrypting and Sending Messages for Non Enrolled Recipients Using a Trusted Intermediary FIG. 7 a illustrates client based creation and delivery of secure messages for recipients who are not enrolled in a PKI using a trusted intermediary 316 in accordance with the present invention. A user associated with a network-connected device 10 who desires to create and send a message on a secure basis (the “Sender”) invokes a client program loaded on the network-connected device 10 . In a preferred embodiment of the present invention the client program would be an email client program such as Microsoft OUTLOOK EXPRESS™. The Sender supplies authentication information (such as username and password) and concludes with submitting the form, typically by pressing a ‘SUBMIT’ button or equivalent. Often email client programs are set up such that user authentication is configured in the email client to automate the authentication process such that it does not require user intervention. The authentication credentials are passed to the email server or message server 306 . The email server or message server 306 authenticates the Sender and then passes back, message waiting lists and other pertinent information about the Sender's email account for display in the Sender's email client 40 in a manner that is known. The Sender prepares a message by completing the appropriate fields of the email client email form referred to, including for example the message subject, body and intended recipients fields. The Security Services 312 is contacted whereby the recipient's(s') public keys and certificates are verified and retrieved from the associated directory 314 or from the sender's address book stored on the email client 40 . In the event that the recipient(s) public key(s) and certificate(s) cannot be retrieved from either location, application 22 of the present invention is invoked to create a shared secret ( FIGS. 4 and 5 ) and retrieves the key pair of the trusted intermediary 316 to secure the message for non-enrolled recipients. The recipient information for non-enrolled recipients including the shared secret question which the recipient must answer ( FIG. 5 ) is(are) stored on the message storage/database server 315 . The message form data is passed to the application 22 , including the email client extension 409 , for signing and encrypting the message and any attachments using the private key of the Sender and the public key(s) of the Recipient(s) and the trusted intermediary 316 for non enrolled recipients, in one embodiment of the invention to form an S/MIME compliant email message. The message is sent from the client to the email server or message server 306 for forwarding to the identified recipients in one embodiment. In another embodiment of the present invention the secured message for non-enrolled recipients is stored to the message storage/database server 315 and an email advisory is generated by the web application 16 and sent to the non-enrolled recipients advising of the secure message waiting and providing instructions on how to retrieve the secure message. In another embodiment, and for reasons of scaleability and efficiency of the encryption algorithm, the secured message for non-enrolled recipients is decrypted by the trusted intermediary 315 , the digital signature is verified, and the message is re-encrypted using a symmetric key unique to the trusted intermediary 316 and stored to the message storage/database server 315 with a copy of the original message stored to a message archive. Client Based Retrieving and Decrypting an Encrypted Message from an Email or Message by Non Enrolled Recipients FIG. 3 b illustrates client based receipt, verification, decryption and display of an encrypted message from an email server or message server 306 or message storage/database server 315 in accordance with the present invention. There are three components required to view and encrypted message: the encrypted message, the client extension 409 and the non-enrolled recipient's private key. The method by which the non-enrolled recipient accesses these components can range from providing a link in an standard email message for the non-enrolled user to access the components as described in the previous section concerning browser based access, to providing all three components as attachments to a standard message as depicted in FIG. 3 b or any combination of the two approaches. As depicted in FIG. 3 b , a non-enrolled user associated with a network-connected device 10 who desires to display an encrypted message that they have received on a secure basis (the “Recipient”) first installs the client extension 409 . When the client extension 409 is available on the network-connected device 10 , the Recipient invokes the decryption process and the encrypted private key for the secure message is passed to the client extension 409 in accordance with this aspect of the present invention. The client extension 409 requests the non-enrolled Recipient to provide the pass phrase in order to decrypt and display the encrypted message. The non-enrolled Recipient supplies the client extension 409 shared secret information in response to the shared secret request ( FIG. 5 ) to the client extension 409 and concludes with submitting the form, typically by pressing a ‘SUBMIT’ button or equivalent. The private key is then passed to the client extension 409 in accordance with this aspect of the present invention where upon the message signature can be verified and the message decrypted for display in the client application 40 . In another aspect of the present invention, the persistent field level encryption disclosed in the patent and Co-Pending patent applications is used for the purposes of the present invention to maintain the confidentiality of the identities of users (and for example their clients with whom they communicate on a secure basis) in accordance with the present invention and other personal information, by encrypting related data and storing the data in an encrypted form at a database (not shown) associated with the web server 106 . The system of the present invention is best understood as the overall system including the network connected device 10 and the resources thereof, including the application 22 , and also the web server 106 and the email server or message server 306 , the message/database storage server 315 as well as the resources of these as well. The computer program of the present invention is the application 22 on the one hand, but also the web application 16 , on the other. Another aspect of the present invention includes the remote key server 310 . FIG. 6 illustrates the interactions involved in signing and encrypting messages in relation to the various components of the PKI infrastructure. A user associated with a network-connected device 10 who desires to create and send an email on a secure basis (the “Sender”) signs on to the web server 106 using the browser 20 loaded on the network-connected device 10 . The web server 106 , and specifically in co-operation with the web application 16 loaded on the web server 106 , responds to the network-connected device 10 by presenting a web page that is a web form requesting that the user associated with the network-device 10 provide authentication in order to gain access to the web application 16 , and specifically a secure message application (not shown) that is included in the web application 16 . The Sender supplies information in the authentication form fields (such as username and password) on the web page and concludes with submitting the form, typically by pressing a ‘SUBMIT’ button or equivalent. The authentication credentials are passed to the web server 106 . The web server 106 in turn delivers the authentication credentials to the email server or message server 306 via the email protocol translator 308 in one embodiment of the application or authenticates user credential for the message storage/database server 315 in an alternate embodiment of the application. Specifically in accordance with the aspect of the present invention whereby the roaming key server 310 is used to access the User Certificate and Private Key from the User Certificate and Private Key Store 302 , the web server 106 also transfers the user credentials to the roaming key server 310 . The email server or message server 306 authenticates the Sender and then passes back, through the email protocol translator 308 , message waiting lists and other pertinent information about the Sender's email account to the web server 106 for display in the Sender's browser 20 and establishes an email session typically using a cookie, in a manner that is known. The web server 106 authenticates the Sender for the message storage/database server 315 and then passes back message waiting lists and other pertinent information about the Sender's account to the web server 106 for display in the Sender's browser 20 and establishes a session typically using a cookie, in a manner that is known. Again, in accordance with the aspect of the present invention utilizing the roaming key server 310 , the roaming key server 310 authenticates the Sender and transmits the Sender's private key and certificate through the web server 106 to the browser extension 309 . In accordance with the aspect of the present invention whereby the User Certificate and Private Key Store 302 resides on the network-connected device 10 , the private key and certificate is accessed by the browser extension 304 . The Sender prepares a message by completing the appropriate fields of the web form referred to, including for example the message subject, body and intended recipient(s) fields. In one particular embodiment of the present invention, the application 22 also provides the recipient(s) the shared secret(s). Security Services 312 is contacted whereby the recipient's(s') public keys and certificates are retrieved and optionally verified from the associated directory 314 or from the sender address book stored on the message storage/database server 315 . In the event that the recipient(s)' public key(s) and certificate(s) cannot be retrieved from either location, application 22 of the present invention is invoked to create a shared secret ( FIG. 4 ) and retrieves the PKC key pair of the trusted intermediary 316 by application 22 to secure the message for non-enrolled recipients. The recipient information for non-enrolled recipients including the shared secret question which the recipient must answer ( FIG. 5 ) is (are) sent by the sender and stored on the message storage/database server 315 . The message form data is passed to the application 22 , including the browser extension 309 , for signing and encrypting the message and any attachments using the private key of the Sender and the public key(s) of the recipient(s) and trusted intermediary 316 for non-enrolled recipients, in one embodiment of the invention to form an S/MIME compliant email message. The message is returned to the browser 20 and sent from the browser 20 to the web server 106 , and using the email protocol translator 308 to the email server or message server 306 for forwarding to the identified recipients in one embodiment of the invention. In another embodiment of the present invention the secured message for non-enrolled recipients is stored to the message storage/database server 315 and an email advisory is generated by the web application 16 and sent to the non-enrolled recipients advising of the secure message waiting and providing instructions on how to retrieve the secure message. In another embodiment, and for reasons of scaleability and efficiency of the encryption algorithm, the secured message for non-enrolled recipients is decrypted by the trusted intermediary 316 , the digital signature is verified, and the message is re-encrypted using a symmetric key unique to the trusted intermediary 316 and stored to the message storage/database server 315 (with an optional copy of the original message stored to a message archive). The method of the present invention is best understood as a process for exchanging PKI encrypted messages and S/MIME messages through a browser, whether a web browser or WAP browser or message client whether personal computer based or wireless device based, for recipients who are not enrolled in a PKI or where the sender does not have access to the PKI credentials of the recipient. The method of the present invention should also be understood as a method for integrating wireless devices with Internet secure messaging using S/MIME or PKI based message encryption for non-enrolled recipients. Another aspect of the method of the present invention is a method for delivering private keys to non-enrolled recipients, through the Internet or a wireless network. Yet another aspect of the method of the present invention, is a method for eliminating the “man in the middle” security hole of proxy based gateways between the Internet and wireless networks by providing persistent secure data communication using S/MIME or PKI for encrypting messages. A still other aspect of the present invention is a method for allocating data resources as between the web server and a wireless device such that PKI is provided on the wireless device so as to provide encryption on a persistent basis. The present invention also provides for persistent field level encryption on a selective basis throughout an Internet-based data process. This promotes efficient utilization of resources by invoking PKI operations in relation to specific elements of an Internet-based data process where security/authentication is most needed. The present invention also provides a set of tools whereby PKI encryption and S/MIME capability is added to a browser in an efficient manner for non enrolled recipients. The present invention should also be understood as a set of tools for complying with legal digital signature requirements, including in association with a wireless device using a web email or client based email system incorporating S/MIME for non-enrolled recipients.

A system for encrypting and decrypting messages using a browser in either a web or wireless device or secure message client software for transmission to or from a web server on the Internet connected to an email server or message server for the situation where the sender does not possess the credentials and public key of the recipients. The encryption and decryption is conducted using a standard web browser on a personal computer or a mini browser on a wireless device, or message client software on either a personal computer or wireless devices such that messages transmitted to the web or wireless browser or message client software can be completed and encrypted and signed by the user such that encrypted and signed data does not require credentials and public key of the recipients. A method for delivering and using private keys to ensure that such keys are destroyed after use is also provided. A method of transmitting encrypted messages to a web or wireless browser or message client and decrypting and verifying such messages by recipients who do not possess or who are not enrolled in a PKI and do not have private keys. A method for authenticating the sender/user of the browser, and a method for accessing or generating public and private keys for encrypting and decrypting messages for recipients who are not enrolled in a public key infrastructure.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present disclosure is related to air conditioning systems. More particularly, the present disclosure is related to methods and systems for controlling air conditioning systems having a free-cooling mode and a cooling mode. [0003] 2. Description of Related Art [0004] During the typical operation of air conditioning systems, the system is run in a cooling mode wherein energy is expended by operating a compressor. The compressor compresses and circulates a refrigerant to chill or condition a working fluid, such as air or other secondary loop fluid (e.g., chilled water or glycol), in a known manner. The conditioned working fluid can then be used in a refrigerator, a freezer, a building, an automobile, and other spaces with climate controlled environment. [0005] However, when the outside ambient temperature is low, there exists the possibility that the outside ambient air itself may be utilized to provide cooling to the working fluid without engaging the compressor. When the outside ambient air is used by an air conditioning system to condition the working fluid, the system is referred to as operating in a free-cooling mode. [0006] As noted above, traditionally, even when the ambient outside air temperature is low, the air conditioning system is run in the cooling mode. Running in cooling mode under such conditions provides a low efficiency means of conditioning the working fluid. In contrast, running the air conditioning system under such conditions in a free-cooling mode is more efficient. In the free-cooling mode, one or more ventilated heat exchangers and pumps are activated so that the refrigerant is circulated by the pumps and is cooled by the outside ambient air. In this manner, the refrigerant, cooled by the outside ambient air, can be used to cool the working fluid without the need for the low efficiency compressor. [0007] Accordingly, it has been determined by the present disclosure that there is a need for methods and systems that improve the efficiency of air conditioning systems having a free-cooling mode. BRIEF SUMMARY OF THE INVENTION [0008] An air conditioning system having a cooling mode and a free-cooling mode. The system having a refrigeration circuit having a compressor and a pump; a suction pressure sensor for measuring a suction pressure of the compressor; a discharge pressure sensor for measuring a discharge pressure of the compressor; a controller for selectively operating in the cooling mode by circulating and compressing a refrigerant through the refrigeration circuit via the compressor or operating in the free-cooling mode by circulating the refrigerant through the refrigeration circuit via the pump; and a recover-refrigerant sequence resident on the controller, the recover-refrigerant sequence being configured to pump the refrigerant in a portion of the refrigeration circuit not used in the free-cooling mode to remaining portions of the refrigeration circuit used in the free-cooling mode when the controller switches from the cooling mode to the free-cooling mode. [0009] A method of controlling an air conditioning system having a cooling mode and a free-cooling mode is provided. The method includes switching the air conditioning system to the free-cooling mode; initiating a recover-refrigerant sequence to recover refrigerant from a portion of a refrigeration circuit that is not used during the free-cooling mode but is used during the cooling mode; and maintaining the air conditioning system in the free-cooling mode after completion of the recover-refrigerant sequence. [0010] The above-described and other features and advantages of the present disclosure will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0011] FIG. 1 is an exemplary embodiment of an air conditioning system in cooling mode according to the present disclosure; [0012] FIG. 2 is an exemplary embodiment of an air conditioning system in free-cooling mode according to the present disclosure; and [0013] FIG. 3 illustrates an exemplary embodiment of a method of operating the air conditioning system of FIGS. 1 and 2 according to the present disclosure. [0014] FIG. 4 illustrates a graph of an exemplary embodiment of the refrigerant recovery sequence according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION [0015] Referring now to the drawings and in particular to FIGS. 1 and 2 , an exemplary embodiment of an air conditioning system (“system”) according to the present disclosure, generally referred to by reference numeral 10 , is shown. System 10 is configured to operate in a cooling mode 12 ( FIG. 1 ) and a free-cooling mode 14 ( FIG. 2 ). [0016] System 10 includes a controller 16 for selectively switching between cooling and free-cooling modes 12 , 14 . Advantageously, controller 16 includes a refrigerant-recovery sequence 18 (“sequence”) resident thereon that monitors pressure in system 10 during the switchover from cooling mode 12 to free-cooling mode 14 . In this manner, system 10 recovers refrigerant from system 10 components that are used in cooling mode 12 , but not in free-cooling mode 14 . This allows the pump to operate during the initiation of free-cooling mode 14 and improves pump reliability. [0017] System 10 also includes a refrigeration circuit 20 that includes a condenser 22 , a pump 24 , an expansion device 26 , an evaporator 28 , and a compressor 30 . Controller 16 is configured to selectively control either compressor 30 (when in cooling mode 12 ) or pump 24 (when in free-cooling mode 14 ) to circulate a refrigerant through system 10 in a flow direction (D). Thus, system 10 , when in cooling mode 12 , controls compressor 30 to compress and circulate the refrigerant in flow direction 30 . However, system 10 , when in free-cooling mode 14 , controls pump 24 to circulate the refrigerant in flow direction 30 . As such, free-cooling mode 14 uses less energy then cooling mode 12 since the free-cooling mode does not require the energy expended by compressor 30 . Moreover, System 10 includes a suction pressure sensor 49 and a discharge pressure sensor 51 . [0018] System 10 includes a compressor by-pass loop 32 and a pump by-pass loop 34 . System 10 includes one or more valves 36 - 1 , 36 - 2 , and 36 - 3 . In one embodiment of the present disclosure valve 36 - 3 is a three-way valve. Valves 36 are controlled by controller 16 in a known manner. Thus, controller 16 can selectively position valves 36 to selectively open and close by-pass loops 32 , 34 as desired. [0019] In cooling mode 12 , controller 16 controls valves 36 so that compressor by-pass loop 32 is closed and pump by-pass loop 34 is open. In this manner, system 10 is configured to allow compressor 30 to compress and circulate refrigerant in the flow direction D by flowing through pump by-pass loop 34 . [0020] In contrast, controller 16 , when in free-cooling mode 14 , controls valves 36 so that compressor by-pass loop 32 is open and pump by-pass loop 34 is closed. In this manner, system 10 is configured to allow pump 24 to circulate refrigerant in the flow direction D by flowing through compressor by-pass loop 32 . [0021] Accordingly, system 10 can condition (i.e., cool and/or dehumidify) a working fluid 38 in heat-exchange communication with evaporator 28 in both cooling and free-cooling modes 12 , 14 . Working fluid 38 can be ambient indoor air or a secondary loop fluid such as, but not limited to, chilled water or glycol. [0022] In cooling mode 12 , system 10 operates as a standard vapor-compression air conditioning system known in the art where the compression and expansion of refrigerant via expansion device 26 are used to condition working fluid 38 . Expansion device 26 can be any known controllable expansion device such as, but not limited to a thermal expansion valve. [0023] In free-cooling mode 14 , system 10 takes advantage of the heat removing capacity of outdoor ambient air 40 , which is in heat exchange relationship with condenser 22 via one or more fans 42 , to condition working fluid 38 . [0024] Although system 10 is described herein as a conventional air conditioning (cooling) system, one skilled in the art will recognize that system 10 may also be configured as a heat pump system to provide both heating and cooling, by adding a reversing valve (not shown) so that condenser 22 (i.e., the outdoor heat exchanger) functions as an evaporator in the heating mode and evaporator 28 (i.e., the indoor heat exchanger) functions as a condenser in the heating mode. [0025] It has been determined by the present disclosure that refrigerant leaving condenser 22 can be in one of several different phases, namely a gas phase, a liquid-gas phase, or a liquid phase. When controller 16 switches system 10 to free-cooling mode 14 , pump 24 is supplied with refrigerant in the different phases until the system reaches a state of equilibrium in full circuit. [0026] After controller 16 initiates free-cooling mode 14 and during the time it takes for system 10 to reach equilibrium, pump 24 is supplied with refrigerant in the different phases. Unfortunately, when pump 24 is supplied with refrigerant in the gas or liquid-gas phases, the pump does not operate as desired. Moreover, the gas phase and/or liquid-gas phase refrigerant can cause pump 24 to cavitate, which can damage the pump and/or the pump motor (not shown). [0027] Turning off pump 24 would stop the potential damage from such cavitation, but also would result in delaying the ability for system 10 to easily switch from cooling mode 12 to free-cooling mode 14 . Advantageously, controller 16 includes sequence 18 that functions to recover refrigerant from system 10 components that are not used during free-cooling mode 14 during the time when system 10 switches out of cooling mode 12 and into free-cooling mode 14 . [0028] System 10 includes a first pressure sensor 44 , a second pressure sensor 46 , a suction pressure sensor 49 , and a discharge pressure sensor 51 in electrical communication with controller 16 . First pressure sensor 44 is positioned at an entrance 48 - 1 of pump 24 , while second pressure sensor 46 is positioned at an exit 48 - 2 of the pump. Controller 16 uses the pressures measured by first and second sensors 44 , 46 to determine a pump pressure difference in real-time. Moreover, controller 16 operates compressor 30 , adjusts the positions of expansion device 26 and valves 36 , and monitors the pressure recorded by a third pressure sensor 49 during the switchover from cooling mode 12 to free-cooling mode 14 . [0029] The operation of sequence 18 is described in more detail with reference to FIG. 3 . FIG. 3 illustrates an exemplary embodiment of a method 50 of controlling system 10 having recover refrigerant in sequence 18 according to the present disclosure. [0030] Method 50 , when system 10 is operating in cooling mode 12 , includes a first free cooling determination step 54 . During first free cooling determination step 54 , method 50 determines whether the temperature of ambient air 40 is sufficient for system 10 to switch to free-cooling mode 14 . If so, method 50 then performs a free-cooling capacity check step 56 wherein system 10 is checked to determine if there is sufficient capacity to operate system 10 in free-cooling mode 14 . If so, method 50 then performs sequence 18 . [0031] Sequence 18 includes a system pump down step 60 and a low pressure equalization step 62 . Initially during sequence 18 , valve 36 - 3 is in a position in accordance with cooling mode 12 , pump 24 is off, and compressor 30 is turned off. [0032] In pump down step 60 , expansion device 26 is closed and compressor 30 is turned on. Compressor 30 remains turned on while a pressure measured by suction pressure sensor 49 is greater than a suction pressure threshold. Compressor 30 is turned off when the pressure measured by suction pressure sensor 49 is less than the suction pressure threshold. There is a pressure differential (“DP”) between suction pressure sensor 49 and discharge pressure sensor 51 . [0033] In equalization sequence 62 , compressor 30 is turned off. When DP is greater than a threshold pressure differential (“DP-threshold”), expansion device 26 is opened at a minimum rate. In one embodiment of the present disclosure, expansion device 26 is positioned approximately 10 percent of a full open position. Expansion device 26 will then close when DP is less than DP-threshold. [0034] Referring now to FIG. 4 , a graph illustrating an exemplary embodiment of sequence 18 according to the present disclosure is shown. As can be seen, system 10 runs in free-cooling capacity check step 56 for approximately eight seconds, wherein sequence 18 is initiated. In sequence 18 , initially, valve 36 - 3 is in a position in accordance with cooling mode 12 , pump 24 is off, and compressor 30 is turned off. During pump down step 60 , expansion device 26 is closed, and compressor 30 is turned on until DP equals approximately 1500 kPa. Equalization sequence 62 is then initiated, wherein expansion device 26 is opened at a minimum while DP is greater than DP-Threshold. In the illustrated embodiment, it is seen that as DP approaches DP-Threshold, the percent opening rate of expansion device 26 decreases to a value of about 3 percent opening rate. [0035] Advantageously, it has been determined by the present disclosure that sequence 18 ensures that there is sufficient compressed refrigerant in liquid form for pump 24 to operate. This improves the reliability of pump 24 when system 10 switches into free-cooling mode 14 . [0036] After sequence 18 has been performed, method 50 switches system 10 into free cooling mode 14 at a free-cooling switching step 64 . [0037] It should be recognized that method 50 is described herein by way of example in use while system 10 is operating in cooling mode 12 . Of course, it is contemplated by the present disclosure for method 50 to find equal use when system 10 is stopped such that sequence 18 avoids pump cavitation during start-up of system 10 into free-cooling mode 14 from a stopped state. [0038] After free-cooling switching step 64 , method 50 includes a pump priming step 66 . After pump 24 has been primed by step 66 , method 50 runs in free-cooling mode 14 at step 68 . System 10 continues to run in free-cooling mode 14 until either controller 16 determines that there is a lack of system capacity at a second capacity determination step 70 or determines that pump 24 is defusing or cavitating at a pump protection step 72 . If either of these conditions are determined to be present, method 50 switches system 10 into cooling mode 12 at a cooling mode switching step 74 . [0039] It should also be noted that the terms “first”, “second”, “third”, “upper”, “lower”, and the like may be used herein to modify various elements. These modifiers do not imply a spatial, sequential, or hierarchical order to the modified elements unless specifically stated. [0040] While the present disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated, but that the disclosure will include all embodiments falling within the scope of the appended claims.

An air conditioning system having a cooling mode and a free-cooling mode. The system having a refrigeration circuit having a compressor and a pump; a suction pressure sensor for measuring a suction pressure of the compressor; a discharge pressure sensor for measuring a discharge pressure of the compressor; a controller for selectively operating in the cooling mode by circulating and compressing a refrigerant through the refrigeration circuit via the compressor or operating in the free-cooling mode by circulating the refrigerant through the refrigeration circuit via the pump; and a recover-refrigerant sequence resident on the controller, the recover-refrigerant sequence being configured to pump the refrigerant in a portion of the refrigeration circuit not used in the free-cooling mode to remaining portions of the refrigeration circuit used in the free-cooling mode when the controller switches from the cooling mode to the free-cooling mode.

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority from U.S. Provisional Patent Application Ser. No. 61/346,976, filed May 21, 2010. FIELD OF THE INVENTION The present invention relates to the art of orthopedic cutting tools, and more particularly, to a disposable cutter used for shaping and preparing the femoral bone for implant insertion. PRIOR ART Cutting tools used in orthopedic procedures are designed to cut bone and associated tissue matter. Specifically, cutters of the present invention are designed to cut and shape the end of a long bone such as a femur or humerus. Typically, the end of the long bone is cut and shaped for insertion of an implant. As such, these cutters are required to be sterile and sharp. Using a dull cutter generates heat that typically leads to tissue necrosis and results in undesireable patient outcomes. A non-sterile cutter blade typically results in an infected and damaged bone that may lead to other problems for the patient. Depicted in FIGS. 1 and 1A are images of a prior art bone cutter 10 designed to cut and shape the femoral head 12 of the femur 14 . As shown in the figures, the prior art cutter 10 is similar to that of a “hole saw” drill. These prior devices 10 generally comprise a hollow cylinder in which a series of cutting teeth slots 16 are formed within the cylinder wall thickness 18 . However, these prior devices 10 do not remove all the bone 14 required to properly fit an implant. Therefore, additional procedures are required to remove this extra bone material 22 and smooth the surface of the bone end 24 . As shown in FIG. 1A , the prior cutter device 10 imparts a channel 20 within the end 24 of the bone 14 . This channel 20 and associated bone material 22 proximate the channel 20 , must be removed to properly fit the implant (not shown) on the end 24 of the bone 14 . Typically, hand tools such as rongeurs are used to remove this extra bone material 22 . Such a bone removal procedure makes it difficult to properly fit an implant over the end 24 of the bone 14 . The extra bone material 22 must be intricately removed to produce a smooth surface and ensure that the bone 14 is shaped to meet the exacting dimensions of the implant. If the implant is not properly fit over the end 24 of the bone 14 , undesirable implant wear or improper implant operation could result. In addition to the inefficient bone removal limitations, traditional bone cutters are typically reused multiple times. That is because of their high cost. Such multiple reuses require that the cutter be cleaned and sterilized before each use. Furthermore, over time, as these cutters are used and reused, they become dull, thus requiring resharpening. Therefore the blades of the cutter are required to be resharpened, cleaned and sterilized. However, these resharpening and sterilization processes add additional costs and increase the possibility of infection. In addition, resharpening tends to deform the dimensions of the cutter. These dimensional changes could adversly impact the optimal fit and function of the implant. Furthermore, there is a high likelihood that the cleaning and sterilization process may not remove all possible infection agents such as bacteria, machining lubricants, and the like. Accordingly, the present invention provides a cost effective single use bone cutter with a novel blade and assembly design that improves cutting efficiency. The enhanced bone cutting and shaping efficiencies of the present invention ensure proper implant fit and reduced implant wear. In addition, the improved bone cutting efficiencies afforded by the present invention, decrease procedural time and minimize patient trauma. Furthermore, the bone cutter of the present invention ensures proper cutter sharpness and cleanliness that promotes optimal patient outcomes. SUMMARY OF THE INVENTION The present invention provides a disposable bone cutter device comprising a cutter assembly and guide rod for orthopedic surgical applications. Specifically, the cutter device of the present invention is designed to re-shape the head of a femur for joint revision surgeries. The cutter assembly comprises a disposable housing and a series of insert blades or a cutter disc arranged in circumferential manner within the assembly. The series of insert blades or cutter disc are preferably secured in the cutter assembly through an interference fit at a distal base portion of the cutter assembly. The housing comprises two cylinders that are joined together at a distal portion of the housing. In a preferred embodiment, a first cylinder is positioned such that its inner diameter circumferentially surrounds the outer diameter of a second cylinder. Both the first and second cylinders are positioned such that they share a common central longitudinal axis. A series of radial connectors join the two cylinders together along the distal base portion of the assembly. In a preferred embodiment, these connectors may take the form of a bar or rod or alternatively be formed into a blade enclosure designed to secure and house the individual insert cutter blades. Furthermore, it is preferred that the distal base portion of the centrally located second cylinder is recessed or offset from the distal base of the first cylinder. This recess establishes an offset rim formed by the wall thickness of the first cylinder. The depth of the offset rim is determined by the gap between the distal base plane of the first cylilnder and the distal base plane of the second cylinder. The offset rim provides a barrier that prevents unintentional damage to nearby bone and/or tissue resulting from contact with the cutting surface of the insert blades or cutting disc. Located at the proximal end portion of the assembly, within the interior of the inner diameter of the centrally located second cylinder, is a boss. The boss comprises a central throughbore that is positioned such that the throughbore is coaxial with the common longitudinal axis. The throughbore of the boss provides an alignment aid to the axis of the desired cut. Another feature of the boss is that it acts as a “stop” to prevent overcutting of the bone. As will be explained in greater detail, the distal end of the boss comes into contact with the end of the bone thus preventing further advancement of the cutter. As such, the position of the boss preferably determines the depth of cut into the bone and prevents unintentional overcutting of the end of the bone. The boss is joined within the interior of the second cylinder through a series of rods which radially extend between the exterior wall surface of the boss and an interior wall surface of the inner diameter of the second cylinder. In addition, these rods serve as an interfacing feature by which the cylindrical cutter attaches to a handle or a motor that rotates the cutter in a clockwide or counterclockwise direction. In a preferred embodiment, the housing can be produced as a single component using an injection molding process. The insert blades are universal and can be manufactured to a minimal size to accommodate all sizes of the cutter. In a preferred embodiment, the series of individual cutter blades are secured within their respective blade enclosures. These blades are preferably of an “L” shape and are designed to provide a cutting edge that extends into the interior of the centrally located second cylinder. The cutter insert blades preferrably include a slot, residing within the surface that extends along the width of the blade. The slot is designed to interface with a post positioned within the blade enclosure. The interaction between the post and slot secures the insert blade therewithin. In this embodiment, the cylindrical cutter is assembled by pressing the insert blades into the blade enclosures of the assembly. The insert blades are designed such that they snap into the blade enclosure. This low cost production process, along with the economical production of the component parts, avoids the need for expensive machining and grinding operations that are common with the prior art. In an alternate embodiment, a cutter disc having a plurality of cutting teeth openings, resides within the distal base portion of the assembly. In a preferred embodiment, the cutting disc comprises an outer diameter, an inner diameter, and a planar surface therebetween. The plurality of cutting teeth are positioned at spaced intervals throughout the planar surface. In operation, the femoral head is first shaped to accept a replacement shell of an implant utilizing the present invention. The shaping of the femoral head is accomplished by first establishing an axis of cut on the femoral head. This axis is established by drilling a guide hole into the femoral head and placing a guide rod into the bone. This guide rod serves to align the axis of the cylindrical cutter to the axis of the intended cut. The cutter of the present invention is then attached to the handle-driver assembly and positioned over the guide rod by means of the hollow boss within the cylindrical cutter. The powered driver provides a means of rotating the cylindrical cutter and advancing the cutter against the femoral head. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a prior art bone cutter and bone. FIG. 1A is a cross-sectional view of the prior art bone cutter and bone shown in FIG. 1 . FIG. 2 is a perspective view of the cutter housing of the present invention. FIG. 3 is an alternate perspective view of the cutter housing of the present invention. FIG. 4 is a cross-sectional view of the cutter housing of the present invention. FIG. 5 is a perspective view of an embodiment of a cutter blade of the present invention. FIG. 6 is a side view of the embodiment of the cutter blade shown in FIG. 5 . FIG. 7 is a perspective view of an alternate embodiment of a cutter blade of the present invention. FIG. 8 is a perspective view illustrating an assembly step of the present invention. FIG. 8A is a perspective view illustrating a preferred embodiment of an assembled bone cutter assembly of the present invention. FIG. 9 is a perspective view of a preferred embodiment of a cutter disc of the present invention. FIG. 10 is a perspective view of the cutter disc and an alternative cutter housing embodiment of the present invention. FIG. 10A is a perspective view of an assembled alternate embodiment of the bone cutter assembly of the present invention shown in FIG. 10 . FIG. 10B is a cross-sectional view of an assembled alternate embodiment of the bone cutter assembly of the present invention shown in FIG. 10 . FIG. 11 is a cross-sectional view of an embodiment of the bone cutter of the present invention being used to shape the end of a bone. FIG. 11A is a cross-sectional view illustrating the shaped end of a bone after using the bone cutter of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now turning to the figures, FIGS. 2-11A illustrate embodiments of a bone cutter 30 of the present invention. In a preferred embodiment, the bone cutter 30 comprises a cutter housing 32 , cutter blades 34 or cutter disc 78 , and a guide rod 36 ( FIGS. 11 , 11 A). As shown in FIGS. 2-4 , 8 , 8 A, and 10 - 11 A, the cutter housing 32 preferably comprises two cylinders, a first cylinder 38 and a second cylinder 40 that are joined therebetween. In a preferred embodiment, the first cylinder 38 comprises a first cylinder inner diameter 42 , a first cylinder outer diameter 44 , and a first cylinder wall thickness 46 therebetween. The second cylinder 40 comprises a second cylinder inner diameter 48 , a second cylinder outer diameter 50 , and a second cylinder wall thickness 52 therebetween. In addition, the first cylinder 38 comprises a first cylinder height 54 extending from a first cylinder distal base portion 56 to a first cylinder proximal end portion 58 . In a preferred embodiment, the distal base portion 56 of the first cylinder 38 is co-planar with an imaginary first cylinder base plane B-B ( FIG. 4 ). This imaginary base plane B-B preferably extends outwardly from the outer diameter 44 of the first cylinder base portion 56 . The second cylinder 40 comprises a second cylinder height 60 extending from a second cylinder distal base portion 62 to a second cylinder proximal end portion 64 . In a preferred embodiment, the distal base portion. 62 of the second cylinder 40 is co-planar with an imaginary second cylinder base plane C-C ( FIG. 4 ). This imaginary base plane C-C preferably extends outwardly from the outer diameter 50 of the second cylinder base portion 62 . In a preferred embodiment, the first and second cylinders 38 , 40 are joined such that the outer diameter 50 of the second cylinder 40 is positioned within the inner diameter 42 of the first cylinder 38 . The first and second cylinders 38 , 40 are further positioned such that they are co-axial to a common central longitudinal axis A-A as shown in FIGS. 2-4 , 8 , 8 A, and 10 - 11 A. In a preferred embodiment, the outer diameter 44 of the first cylinder 38 ranges from about 5 cm to about 10 cm, the inner diameter 42 of the first cylinder 38 ranges from about 4.5 cm to about 9.95 cm and the height 54 of the first cylinder 38 ranges from about 1 cm to about 4 cm. The wall thickness 46 of the first cylinder 38 preferably ranges from about 0.05 cm to about 0.5 cm. In a preferred embodiment, illustrated in FIGS. 2-4 , 8 , 8 A, and 10 - 11 A, the height 60 of the centrally located second cylinder 40 is greater than that of the height 54 of the first cylinder 38 . Furthermore, the height 60 of the centrally located second cylinder 40 ranges from about 5 cm to about 10 cm. The outer diameter 50 of the second cylinder 40 ranges from about 3 cm to about 6 cm and the inner diameter 48 of the second cylinder 40 ranges from about 2 cm to about 6 cm. The wall thickness 52 of the second cylinder 40 ranges from about 0.05 cm to about 0.5 cm. The two cylinders 38 , 40 are joined together by a connector 66 that interfaces between the two cylinders 38 , 40 at a distal end portion 67 of the housing 32 as shown in FIG. 10 . The connector 66 can be of many non-limiting forms such as a bar, a rod, a rectangle or a sphere such that one surface interfaces with the interior wall surface 68 of the inner diameter 42 of the first cylinder 38 and an opposite surface interfaces with the exterior wall surface 70 of the outer diameter 50 of the second cylinder 40 . In a preferred embodiment, a plurality of two or more connectors 66 , radially extend between the inner and outer diameters 42 , 50 of the first and second cylinders 38 , 40 , respectively, and join them therebetween as shown in FIG. 10 . In a preferred embodiment, the connector 66 can be designed as a blade enclosure 72 such that individual insert blades 34 ( FIGS. 2-3 , and 8 - 8 A) are disposed therewithin. This preferred blade enclosure 72 embodiment, will be discussed in more detail. As shown in the embodiments illustrated in FIGS. 3-4 , 8 - 8 A, and 10 - 10 A, the housing 32 is preferably constructed such that an offset rim 74 is formed by a portion of the wall thickness 46 of the first cylinder 38 . The depth 76 of the offset rim 74 is defined by the distance between the first and second imaginary distal base planes B-B, C-C as shown in the cross sectional view of FIG. 4 . In a preferred embodiment, the offset rim 74 preferably has a depth 76 that ranges from about 0.01 cm to about 0.05 cm. The offset rim 74 preferably extends around the perimeter of the first cylinder 38 at the distal base portion 56 . The thickness of the offset rim 74 is defined by the wall thickness 46 of the outer first cylinder 38 . The offset rim 74 is designed to prevent the cutter blades 34 or cutter disc 78 ( FIG. 9 ) from inadvertently damaging nearby bone or tissue, particularly preventing a proximal bone or tissue from being cut or nicked. However, it is contemplated that the housing 32 could be constructed such that the first and second imaginary planes B-B, C-C are coplanar, therefore constructing a housing 32 without an offset rim 74 . It is preferred that both the first and second cylinders 38 , 40 have a hollow interior 80 , 82 within their respective inner diameters 42 , 48 . Such a hollow interior 80 , 82 allows for efficient removal of bone debris as the debris can freely flow through the cutter assembly 84 ( FIGS. 8 , 8 A). It is also contemplated that such a housing 32 , could be constructed with a cylinder having a solid or partially solid interior. In a preferred embodiment shown in FIGS. 2 , 4 , 8 A, and 11 - 11 A, the cutter housing 32 has a boss 86 that is positioned within the inner diameter 48 of the second cylinder 40 . More specifically, the boss 86 is centrally positioned within the inner diameter 48 of the second cylinder 40 . In a preferred embodiment, the boss 86 comprises a throughbore 88 . The boss 86 is preferably further positioned within the inner diameter 48 of the second cylinder 40 such that the throughbore 88 is co-axially aligned with the central axis A-A of the housing 32 as shown in FIGS. 2 , 4 , 8 A, and 11 - 11 A. In a preferred embodiment, illustrated in FIG. 4 , the boss 86 is constructed with a distal planar edge 90 . This distal planar edge 90 is designed to act as a “stop” to prevent further advancement of the cutter 30 into the end 24 of the bone 14 . The boss 86 is preferably positioned with the interior 82 of the second cylinder 40 such that a cut depth 92 is defined between the distal planar edge 90 of the boss 86 and the imaginary second cylinder base plane C-C. It is contemplated that this distal planar edge 90 can be positioned anywhere within the interior 82 of the centrally located second cylinder 40 to establish an optimal cut depth 92 for a particular implant (not shown). In a preferred embodiment the cut depth 92 ranges from about 2 cm to about 10 cm. A plurality of bars 94 secure the boss 86 within the inner diameter 48 of the centrally located second cylinder 40 . A plurality of bars 94 , having a length 96 from about 4 cm to about 8 cm and a thickness 98 from about 0.5 cm to about 1 cm, fluidly extend from the interior wall surface 68 of the inner diameter 48 of the first cylinder 38 to the exterior wall surface 70 of the outer diameter 50 of the second cylinder 40 within the proximal portion 64 of the housing 32 . It is preferred that a plurality of at least two bars 94 , connect the boss 86 within the interior 82 of the second cylinder 40 . It is preferred that the housing 32 be composed of a biocompatible material. In a preferred embodiment, the cutter housing 32 is composed of a biocompatible thermoplastic such as, but not limited to, Acrylonitrile Butadiene Styrene (ABS), Polyarylamide (PAA), or Polyetheretherketone (PEEK). Furthermore it is preferred that the series of cutter blades 34 are positioned in a radial fashion about the outer diameter 50 of the second cylinder 40 as illustrated in FIGS. 8 and 8A . More specifically, these cutter insert blades 34 are positioned between the exterior surface 70 of the outer diameter 50 of the second cylinder 40 and the interior surface 68 of the inner diameter 42 of the first cylinder 38 at the distal base portion 56 of the housing 32 . Preferred embodiments of the cutter insert blade 34 , 130 are shown in FIGS. 5-7 . As illustrated, insert blades 34 , 130 comprise a blade proximal portion 100 and a blade distal portion 102 . The widths 104 , 106 of the proximal and distal portions 100 , 102 are not necessarily equal. In a preferred embodiment, the width 106 of the distal portion 102 is greater than the width 104 of the proximal portion 100 . An insert blade cutting surface 108 preferably extends along the distal width 106 of the insert blade 34 , 130 . In a preferred embodiment, when inserted into the bone cutter housing 32 , the plurality of these blade cutting surfaces 108 align to form an imaginary blade cutting surface plane D-D ( FIG. 4 ). It is further preferred that this imaginary blade cutting surface plane D-D reside between the imaginary first and second cylinder planes B-B, C-C. As shown in FIGS. 5 , 7 and 8 A, the distal width 106 of the insert blade 34 , 130 is greater than the proximal width 104 of the blade 34 , 130 . This extra “width portion” of the insert cutter blade 34 , 130 is defined as the blade extension portion 110 . The blade extension portion 110 is designed such that when the cutter blade 34 , 130 is inserted into the housing 32 , the extension portion 110 protrudes past the inner diameter 48 of the second cylinder 40 towards the interior 82 of the second cylinder 40 . In addition, the blade extension portion 110 acts as a “free end”. This “free end” extension is designed to cut into the head 12 of the bone 14 . As such, this “free end” extension 110 defines a new diameter 112 of the bone head 12 as illustrated in FIG. 11A . If such an extension 110 were not present, the interior wall 69 of the second cylinder 40 would prevent cutting of the bone 14 . In a preferred embodiment, the blade extension 110 has a width from about 0.05 cm to about 0.10 cm. As illustrated in FIGS. 5 and 6 , a groove 114 is preferably formed within the surface 116 of the distal end portion 102 of the insert blade 34 . In a preferred embodiment, the groove 114 has a “V” shape. The groove 114 is designed to establish a rake angle θ of the insert blade 34 . The rake angle θ is defined as the intersection between the distal surface 120 of the “V” cut out portion 114 and a perpendicular line E-E to the cutting edge surface 108 as shown in FIG. 6 . It is preferred that rake angle θ range from about 4° to about 30°. A relief angle Ø, as illustrated in FIG. 6 , is formed between the intersection of the distal end surface 124 of the blade 34 and a tangent line F-F to the blade cutting edge 108 . It is preferred that the relief angle Ø range from about 4° to about 20°. Each cutter blade 34 , 130 is preferably positioned within the cutter blade enclosure 72 as shown in FIGS. 8 and 8A . In a preferred embodiment, the insert blade 34 , 130 is positioned in the housing 32 such that the proximal end portion 104 of the insert blade 34 , 130 resides inside the blade enclosure 72 and the cutting surface 108 of the insert blade 34 , 130 lies outside the blade enclosure 72 . Furthermore, it is preferred that the cutting surface 108 of the insert blade 34 lies parallel to an imaginary cutting plane D-D as shown in FIG. 4 . As shown in FIG. 4 , the imaginary cutting plane D-D lies between the first cylinder imaginary plane B-B and the second cylinder imaginary plane C-C. The blade extension 110 preferably is positioned towards the central axis A-A of the assembly 84 . In a preferred embodiment shown in FIGS. 2 and 3 , each cutter blade enclosure 72 has a post 126 therewithin. The post 126 is preferably designed to snap-fit into a slot 128 within the proximal end portion 100 of the cutter blade 34 ( FIGS. 5 and 6 ). Once the post 126 snaps into the slot 128 , the insert blade 34 is locked within the cutter blade enclosure 72 . In an alternative embodiment, as shown in FIG. 7 , the insert blade 130 can be designed without a groove 114 and slot 128 . In this embodiment, the cutting edge 108 is formed at the intersection of the side blade surface 116 and the distal end surface 124 . It is preferred that a portion of the surface 116 at the proximal end portion 100 of the insert blade 130 has a roughened finish 132 . This roughened surface finish portion 132 provides for a more secure fit when positioned within the blade enclosure 72 . In a preferred embodiment, insert blades 34 , 130 are secured within the blade enclosure 72 with an induction bonding process. Alternatively, the insert blade 34 , 130 can be secured by an alternate means not limited to adhesives, overmolding, press fitting, induction bonding, and the like. In an alternate embodiment, the cutting disc 78 is positioned at the distal end portion 67 of the housing 32 . The cutting disc 78 embodiment provides an additional means of bone removal which is illustrated in FIGS. 9-10A . An embodiment of this alternate cutter assembly 146 is shown in FIG. 10A . The assembly 146 of this embodiment comprises the housing 32 and the cutter disc 78 . The cutting disc 78 preferably comprises an outer disc diameter 134 , an inner disc diameter 136 and a planar surface 138 therebetween. The cutting disc 78 is positioned between the wall thickness 46 of the first cylinder 38 and the wall thickness 52 of the second cylinder 40 at the distal end portion 67 . More specifically, it is preferred that the cutting disc 78 be placed between the inner diameter 42 of the first cylinder 38 and the inner diameter 48 of the second cylinder 40 such that the planar surface 138 of the cutting disc 78 is parallel to the first and second cylinder imaginary planes B-B, C-C ( FIG. 10B ). Positioned throughout the surface 138 of the disc 78 are a series of openings 140 . These openings 140 are preferably positioned throughout the surface 138 of the disc 78 in a helical pattern. Protruding from the opening 140 is a cutting tooth 142 . The cutting teeth 142 are designed such that a cutting surface 144 is positioned outwardly from the planar surface 138 of the disc 78 . Alternately, the cutting surface 144 may protrude inwardly from the surface 138 of the disc 78 . In a preferred embodiment, these cutting surfaces 144 of the cutting teeth 142 align to form an imaginary cutting disc plane G-G. This imaginary plane G-G preferably resides between the first and second imaginary cylinder planes B-B, C-C ( FIG. 10B ). It is preferred that the cutter insert blades 34 , 130 and the cutting disc 78 are composed of a biocompatible metal. In a preferred embodiment, such biocompatible metals include, but are not limited to, stainless steel, MP35N, titanium, and combinations thereof. It is most preferred that cutter blades 34 , 130 and the cutting disc 78 are composed of a 300 series stainless steel. In a preferred embodiment, the cutter housing 32 is first molded from a biocompatible polymer as previously mentioned. After the housing 32 has been molded, the cutter blades 34 , 130 or cutter disc 78 are then inserted in the distal base portion 67 of the housing 32 . As previously mentioned, an induction bonding process is preferably used to secure the cutter blades 34 , 130 or cutter disc 78 to the molded assembly 84 , 146 . Alternatively, adhesives, overmolding, press fitting, and the like may also be used. In this preferred bonding embodiment, electromagnetic current is used to heat the blades 34 , 130 or blade disc 78 . Heat generated from the current, melts the surrounding assembly polymer material, causing the material to flow and engage the cutter blades 34 , 130 or disc 78 . It is well known that alternative processes such as cross pinned engagements, direct insert molding, or ultrasonic insertion may also be used to strengthen the connection or act as a primary means to join the bone cutter 30 of the present invention. FIGS. 11 and 11A illustrate the use of the bone cutter 30 of the present invention. Initially, a guide-hole 148 is drilled into the end 24 of a bone 14 . The guide rod 36 is placed into the guide-hole 148 and the cutter assembly 84 , 146 is placed over the rod 36 as shown. In a preferred embodiment, the guide rod 36 is preferably positioned through the central axis A-A of the bone cutter 30 . Once in place over the end 24 of the bone 14 , the cutter 30 is rotated in either a clockwise or counterclockwise direction. This rotational movement of the cutter 30 , removes bone material from the end 24 of the bone 14 with a smooth surface finish with a bone diameter 112 suitably sized for insertion of an implant (not shown). Once the bone head 12 is properly shaped, the cutter 30 and guide rod 36 are removed. An implant (not shown) is then positioned over the end 24 of the bone 14 . Now, it is therefore apparent that the present invention has many features and benefits among which are promoting proper implant fit, decreased procedural times and minimized patient trauma. While embodiments of the present invention have been described in detail, that is for the purpose of illustration, not limitation.

A single use bone cutter comprised of two concentric cylinders and a series of insert blades or cutter disc is described. The cutter blades or cutter disc is preferably positioned at the distal end of the cutter. The bone cutter also comprises a guide rod that aids in the line of sight when using the cutter device.

FIELD OF THE INVENTION The present invention relates to a rotary device for mounting at intersections of a transport rail system comprising transport units. It serves for guiding the transport units to the transport rails running in any direction and for simultaneously ensuring the supply of power and of control signals to the transport units. Mounted on the transport units are, for example, lamps which are supplied with energy and possibly control signals by the transport units and thus ensure flexible and, if required, even mobile illumination of a room, for example a television studio. DESCRIPTION OF THE PRIOR ART Conventional lighting systems for television studios, theater stages or the like have, for example, spotlights which are mounted on a transport rail system present on the ceiling and comprising turntables and can be manually positioned on the rails. Supply boxes from which a positioned spotlight can be supplied with power and control signals are mounted at regular intervals on the ceiling. However, such an arrangement requires relatively early and manual preparation for the event for which the lighting system is to be used and makes flexible, short-term adaptation of the lighting situation more difficult. Another system for a lighting system envisages mounting a large number of spotlights which are adjustable only in height, it being possible, depending on requirements, to use those spotlights which are located in the suitable place. Only the height of the spotlights can be freely chosen. Although this system permits flexible work, it requires large investments in expensive spotlight systems and considerably limits the number of systems from which a spotlight can be used. Yet another system is based on a transport rail system which can be installed in the ceiling structure of a studio. Thus, a transport rail system has rails which are parallel to one another and run over the entire length of the region in which spotlights are to be used. In each case a plurality of rail sections whose direction of travel is perpendicular to the direction of travel of the rails are mounted displaceably on a pair of such rails. The spotlights are fastened to transport units which can be pushed onto the rail sections. Two rail sections on adjacent pairs of rails can then be brought into position so that they are flush with one another and a transport unit of a spotlight can be moved from one rail section to the next. In this way, a spotlight can in principle be brought to any desired position on the ceiling. however, such a system has the substantial disadvantage that the transport distances on the rail system are long and inconvenient if the lighting system has a relatively large number of spotlights which possibly also are of various design and perform various functions, since rail sections occupied by transport units hinder one another during changes of position. SUMMARY OF THE INVENTION It is the object of the present invention to permit a lighting system which does not have the disadvantages of the systems described above and in which the lamps can be flexibly moved even while they are in use. The invention relates to a rotary device, namely a rotary device for mounting at intersections between stationary transport rails which are provided with contact tracks and form part of a transport rail system for conveying transport units, the rotary device having two components which are rotatable relative to one another and of which one is in the form of a pivot bearing for the other, which rotary bearing serves for fastening at the intersection, while the other is a rail support containing at least one rail section. In the device according to the invention, each rail section of the rail support is provided with contact tracks so that a transport unit present on the rail section and having a current collector can obtain energy. Furthermore, the invention also relates to a lighting system comprising lamps for illuminating television studios, theater or concert stages or the like, wherein the lamps are provided with transport units which can be positioned on a transport rail system comprising transport rails having contact tracks, these transport units having current collectors which make contact with the contact tracks, and wherein one rotary device as described above is present at each of the intersections of this transport rail system. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention is explained below with reference to a drawing. In the drawing, FIG. 1 shows a perspective view of a rotary device according to the invention, FIG. 2 shows a perspective view of the pivot bearing of this device, FIG. 3 shows a view, also a perspective one, of its rail support, FIG. 4 shows a longitudinal section through the rail section of the rail support with mounted trolley shown uncut and FIG. 5 shows a perspective view of a part of a lighting system which is provided with rotary devices according to the invention, with a lamp shown schematically. DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, the rotary device consists of two components, of which one in the form of a pivot bearing, denoted as a whole by 1 and to be installed firmly at intersections of the transport rail system, for the other, denoted as a whole by two, and referred to below as rail support. The pivot bearing 1 essentially comprises a hollow cylinder 11 having an external diameter D a and an internal diameter D i . This is provided with threaded holes 12 which can be engaged by fastening means in order to fasten the rotary device to a ceiling or to a scaffolding. Depending on the structure of the transport rail system, for example, eight rail attachments 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 of stationary transport rails are fixed to the cylinder 11 and are led radially outward from the cylinder surface, in each case two adjacent attachments making an angle of 45° with one another. The rail support 2 likewise essentially comprises a hollow cylinder 50 whose external diameter d a is slightly less than the internal diameter D i of the hollow cylinder 11 belonging to the pivot bearing 1 . It is additionally provided at the top with a flange 51 having an external diameter d f which is at least equal to D a . Mounted in the lower part of the rail support is a rail section 52 which runs along a diagonal of the cylinder 50 . Each of the rail attachments 21 to 28 as well as the rail section 52 are symmetrical with respect to a plane which runs along the rail direction and is vertical in the example shown. Each rail attachment 21 to 28 or each rail section 52 has a ceiling 31 , two side walls 32 , 33 and two runways 34 , 35 . A transport unit 70 in the form of a trolley is displaceable on the runways 34 , 35 , along the direction of travel of the rail. A plastics band 36 is mounted on each of the two side walls 32 , 33 of the rails. Each of the plastics bands is provided with at least two grooves, each of which contains a current-carrying rail 37 or 38 which is opened toward the inside of the rail and serves as a contact track. Those contact tracks 37 , 38 of the rail attachments 21 to 28 which are opposite one another make contact with one another via connections 46 , 47 . The connections 46 , 47 can be, for example, in the form of current-carrying cables mounted on the outside of the rail attachments 21 to 28 , which cables make contact with the contact tracks 37 , 38 through orifices in the side walls 32 , 33 . Also mounted in the interior of the hollow cylinder 11 of the pivot bearing 1 of the rotary device is a plastics band 41 with inserted current-carrying rails 42 , 43 which are connected directly to the current-carrying rails 37 , 38 of the rail attachments 21 to 28 . The rail support 2 has contact pins 44 , 45 which are connected to the contact tracks 37 , 38 of the rail section 52 and, in the state ready for operation, are pressed, for example by a spring, against the current-carrying rails 42 , 43 so that they make electrical contact with them. The trolley 70 shown schematically in FIG. 4 has a plurality of axles with wheels 71 running on the runways 34 , 35 , and drive means by which it can be moved along the rail. Current collectors 72 which slide along the contact tracks 37 , 38 are mounted on that side of the trolley 70 which faces the observer in FIG. 4 . In the embodiment shown in FIG. 2, the trolley 70 has one set of current collectors each at the front and rear in the direction of travel, only two current collectors 72 being present per set, corresponding to the number of contact tracks 37 , 38 . However, the number of current collectors does of course increase with the number of contact tracks 37 , 38 , if more than two of these are present. In addition, the trolley also has wheels 73 which are mounted at its top and, by running on the ceiling 31 , prevent the trolley 70 from rearing up at large accelerations and the current collectors from losing contact with the current-carrying rails 37 , 38 . In the state ready for operation, the rail support 2 , as shown in FIG. 1, is inserted into the pivot bearing 1 of the rotary device. Present between the flange 51 and the upper edge 11 a of the cylinder 11 is a roller bearing 61 which makes it possible for the rail support 2 to be turned with little resistance against the pivot bearing 1 . For this purpose, the rail support 2 has an actuator. An electric motor 63 connected via supply cables 62 to the current-carrying rails 37 , 38 of the rail section 52 is fastened to the inside of the rail support 2 . If required, said motor produces a rotation of the rail support via a plastics gear wheel 64 which engages, through an orifice 65 in the cylinder 50 , the teeth of a plastics toothed rack 66 countersunk in the inner surface of the cylinder 11 . In addition, spherical indentations 67 are provided at predetermined positions at an angular spacing of 45° relative to one another on the inside of the hollow cylinder. A ball 68 is mounted on the outside of the cylinder 50 and is pressed outward by a spring against a stop or, in the state ready for operation, against the inside of the cylinder 11 . It then snaps into one of these indentations when the rail support is aligned in such a way that one of the rail attachments 21 to 28 is in the direction which leads radially outward from its rail section 52 . In this way, the positions in which a transport unit can be moved onto the rail support 2 or away from it are defined as fixed positions of the rail support 2 . The structure and the mode of operation of a lighting system provided with rotary devices according to the invention are described briefly below. FIG. 5 shows a view of a part of such a lighting system comprising a lamp 80 shown only schematically. The lamp 80 is, for example, a spotlight having a set of color filters and a device for inserting a filter from this set. As is known for traditional lighting systems, it is provided with means by which its height can be adjusted and by which its light can be thrown in any desired direction. The spotlights, together with the device for inserting the color filters, are supplied with power via the contact tracks and via the trolley 70 . For feeding current and, depending on requirements, control signals into the contact tracks 37 , 38 , 42 , 43 of the transport rail system, one of the rails installed in a fixed position is in contact with cables which are connected to a power unit and, if required, control devices. The contact tracks 42 , 43 of the pivot bearing 1 , together with the connections 46 , 47 , which connect together the opposite contact tracks 37 , 38 of the stationary rails, and with the connections to the rail sections 52 of the rail support 2 via the contact pins 44 , 45 , ensure that the entire rail network is continuously connected to power units and control devices, subdivision into sectors which in each case have a separate power supply also being possible in the case of relatively large lighting systems. In this case, the trolley of each transport unit, as shown in FIG. 4, has two sets of current collectors one behind the other in the direction of travel and a relay circuit which switches back and forth between the two current collector sets to prevent a trolley from short-circuiting two sectors with one another. The lighting system also has a central control unit not shown in the drawing. With the aid of this control unit, the position and current function of each spotlight can be continuously adapted to the requirements according to a predetermined program or by direct operation. The actuation of the spotlights, of the devices for inserting the color filters, of the trolleys and of the actuators by the control unit is then effected either by a control signal modulated on the power supply, via additional contact tracks for control signal transmission which are not shown in the drawing and are parallel to the current-carrying rails 37 , 38 shown or via an infrared remote control. The continuous power and control signal supplied to the spotlight independently of their position make it possible for them to change their position even during use, permitting novel and spectacular lighting effects during performances, for example at rock concerts. However, because the rotary device according to the invention is provided with an actuator with quiet force transmission via a plastics gear wheel, a lamp can be readily moved, for example in television studios during a broadcast, ensuring greater flexibility in comparison with conventional lighting systems and in particular permitting work with fewer spotlights. Finally, it should also be mentioned that the rotary device described above is by no means the only possible embodiment of the invention and can also be modified in many respects. Thus, for example, it is entirely possible for the entire power supply to operate on the basis of three-phase current, in which case the number of contact tracks 38 , 39 would of course correspondingly increase. It is also entirely possible for a rail support 2 to have more than one rail section 52 . If, for example, two intersecting rail sections making an angle of 90° with one another are mounted on each rail support 2 , the maximum angle through which the rail support has to be turned before a transport unit 70 can be moved from a predetermined stationary rail onto one of its rail sections can be reduced to 45°. In this way, the speed with which the positions of the transport units 70 can be adapted can additionally be increased. It is of course also possible for the structure of the transport rail system to differ from the embodiment shown schematically in FIG. 5 . The rotary device can be installed, for example, in such a way that one rotary device is directly adjacent to the next one, so that the transport units can travel directly from one rail support 2 to the next one without having to travel over fixed rails. In this case, the pivot bearing 1 would of course have not eight rail attachments 21 to 28 but, for example, only four thereof, which would run in the diagonal directions of the transport system. It is not only lamps which are suitable transport units. For example, it is also entirely possible for television cameras, loudspeaker boxes, etc. by themselves or in combination with lamps to be positioned in a flexible and mobile manner on a transport rail system provided with the rotary devices according to the invention. The rotary device is of course also suitable for applications other than for the entertainment sector, for example for use for program-controllable transport devices in a warehouse.

The invention relates to a rotary device for use for lighting systems which ensure flexible and, if required, even mobile illumination of a room, for example of a television studio. The rotary device according to the invention is mounted at intersections of a transport rail system for conveying transport units, for example lamps. It has two components which can be rotated relative to one another and of which one is in the form of a pivot bearing, serving for fastening at the intersection, for the other, while the other is a rail support containing at least one rail section. According to the invention, each rail section of the rail support is provided with contact tracks so that the transport unit present on the rail section and having current collectors can obtain energy.

CROSS-REFERENCE TO RELATED APPLICATION [0001] The present application relates to and claims priority to German Patent Application 102015220178.3, filed Oct. 16, 2015, the entirety of which is hereby incorporated by reference. BACKGROUND OF THE INVENTION Field of the Invention [0002] The invention relates to a capacitive pressure measuring cell for detecting the pressure of a medium adjacent to the pressure measuring cell according to the preamble of claim 1 and a pressure measuring device including such a pressure measuring cell. [0003] Capacitive pressure measuring devices or pressure sensors are used in many industrial fields for pressure measurements. They often comprise a ceramic pressure measuring cell as a transducer for the process pressure and an evaluation unit for signal processing. [0004] Typical measuring cells consist of a compact unit comprising a ceramic base body and a membrane, wherein a glass solder ring is disposed between the base body and the membrane. The cavity thus obtained between the base body and the membrane allows the longitudinal movement of the membrane due to a pressure impact. At the bottom side of the membrane and at the opposite upper side of the base body respective electrodes are provided which together form a measuring capacitor. By the action of pressure a deformation of the membrane is caused resulting in a change in capacitance of the measuring capacitor. [0005] For contacting the electrodes through holes are provided in the base body of the pressure measuring cell on the opposite side of the membrane in a number corresponding to the number of the electrodes. These through holes lead up to the electrodes and comprise an electrically conductive coating at their inner wall over their entire length. A contact pin is inserted into the exit opening of each through hole on the upper side of the base body and an electrical contact with the coating is made using a solder joint such that the electrode can be electrically contacted via the pin. [0006] Such a pressure measurement cell is inter alia known from the documents DE 102012213572 A1, DE 102012208757 A1 and DE 102013213857 A1 of the present applicant, wherein in the former in order to make an electrical contact the printed circuit board rests directly on the coating and thus no pin is required. The production of vias in a substrate is known, for example, from DE 10243961 A1. [0007] A key consideration in such pressure measuring cells is inter alia the mechanical pressure limit, that is how long the measuring cell can withstand a predetermined excess pressure before it is damaged and thus the risk arises that the pressurized medium passes into the interior of the measuring device. Although the strength can be increased when a thicker base body is provided, this measure, however, results in manufacturing problems. For example, with increasing thickness of the base body the formation of the through hole and the conductive inner coating within the through-hole becomes more difficult. Moreover, thereby also the overall construction of the measuring device is extended, which is contrary in particular to the requirements of a configuration as compact as possible. [0008] It is an object of the invention to improve the mechanical pressure limit of the pressure measuring cell without changing the fundamental configuration of known pressure measuring cells of the type in question, in particular as regards the material thickness. SUMMARY OF THE INVENTION [0009] This object is achieved by a pressure measuring cell comprising the features of claim 1 and by an electronic pressure measuring device according to claim 7 . Advantageous embodiments of the invention are specified in the subclaims. [0010] According to the invention the end portions of the through holes at the upper side of the base body each have a funnel shaped extension, wherein the exit edge of each funnel-shaped extension is formed in the shape of an ellipse such that the notch effect is smaller than in a circular form. Herein, the funnel shaped extension is configured such that each exit opening of the through holes at the upper side of the base body at least partially forms a bevel—also referred to as counterbore. By means of the elliptical profile of the exit edges the bevels extend with varying angles. Preferably, the major axes of the ellipses are aligned tangentially. It should be noted that the term “elliptical shape” also means any oval shapes. [0011] The thus achieved technical effect is the reduction of the mechanical stresses obtained by the pressure impact in the base body. This effect is achieved by increasing the radius at the exit opening of the through hole at the upper side of the base body of the pressure measuring cell, while the diameter of the through hole itself remains unchanged. In simple terms this can be expressed so that the radially extending stress flows at the surface of the base body are bypassed by the elliptical shape quasi “laminar” around the obstacle, that is the through hole. Specifically, this means that by means of the elliptical shape the respective occurring notch effect is smaller compared to a circular shape such that in particular occurring tensile stresses are reduced. As a result, by reducing mechanical stresses an increase in strength is achieved which ultimately leads to the fact that the pressure measuring cell can withstand predetermined excessive pressures for a longer time or even higher excessive pressures for the same configuration and unchanged dimensions. [0012] Preferably, the major axes of the ellipses are therefore oriented tangentially. The bevels advantageously have a uniform, i.e. stepless behaviour from the circumference of the through hole up to their exit edge. This inter alia brings about advantages in manufacturing. [0013] Although the invention relates to a capacitive pressure measuring cell it is likewise applicable to resistive measuring cells in which the pressure measurement takes place by means of strain gauges and which comprise a ceramic base body. [0014] The pressure measuring device according to the invention substantially consists of a process connection, a housing and a pressure measuring cell according to the invention. The process connection mostly includes the pressure measuring cell and provides the mechanical connection to a container which accommodates the medium to be measured. The housing is mounted onto the process connection. In the housing in particular the electronic unit necessary for processing and conditioning the measured values into a measurement signal is disposed. In addition, a connector for power and/or signal transmission as well as a display and control unit may be provided at the housing. BRIEF DESCRIPTION OF THE DRAWINGS [0015] The invention will now be explained with reference to an exemplary embodiment shown in the drawings. In the drawings: [0016] FIG. 1 is a schematic cross-sectional view of a pressure measuring cell according to the invention; and [0017] FIG. 2 is a top view of a pressure measuring cell according to the invention. DETAILED DESCRIPTION [0018] In the following description of the preferred embodiments like reference numerals designate identical or comparable components. [0019] FIG. 1 shows a capacitive pressure measuring cell 1 comprising a ceramic base body 3 and a measuring membrane 2 likewise made of ceramic. The measuring membrane 2 and the base body 3 are held spaced apart from each other at the edge by means of a spacer 13 made e.g. of glass, glass solder or a glass alloy and are connected to each other, such that a measuring chamber 4 is formed between the membrane 2 and the base body 4 . [0020] The measuring membrane 2 contacts at its outer side a medium the pressure of which is to be measured by means of the measuring cell 1 . The measuring chamber 4 between the base body 3 and the membrane 2 enables the longitudinal movement of the membrane 2 due to a pressure impact. At the inner sides of the membrane 2 and the opposite base body 3 respective electrodes 10 , 11 , 12 are provided, which together form at least one measuring capacitor. The pressure impact causes a deformation of the membrane 2 resulting in a change in capacitance of the measuring capacitor. [0021] For contacting the electrodes 10 , 11 , 12 a respective through hole 20 is provided in the base body 3 . The through holes 20 are provided with a conductive coating. On the upper side 3 a of the body 3 a respective contact pin 23 is inserted into the exit openings 21 of the through holes 20 which is preferably connected electrically conductive to the coating by means of a solder. For connecting the electrode 10 disposed on the membrane 2 in addition an electrical connection over or through the spacer 13 is required. In this way the electrodes 10 , 11 , 12 can be electrically contacted from the upper side 3 a of the body 3 , i.e. the change in capacitance occurring between the electrodes due to a pressure impact can be tapped. [0022] The through hole 20 in the center is shown in phantom because actually it is not visible in a section through the center of the pressure measuring cell. Here it is again stressed that the view shown in FIG. 1 is a schematic diagram or principle sketch in which the focus is directed at the illustration of the invention. In particular, the contacting of the electrode 12 by means of the inclined extending through hole 20 can be realized differently. In approximate agreement with FIG. 2 this representation has been selected here. [0023] In FIG. 1 the end portions 21 a of the through holes 20 with the funnel-shaped extensions can be seen. According to the invention the exit edges of the funnel-shaped extensions are not configured circular, but elliptical, as is obvious in FIG. 2 . [0024] FIG. 2 shows a top view of a pressure measuring cell according to the invention. The exit openings 21 of the through holes 20 at the upper side 3 a of the base body 3 are arranged along an imaginary circular line K. The circular line K has only been shown here in dashed lines in order to illustrate the aspect of the arrangement. Also indicated is a respective contact pin 23 which is disposed at the center in the through holes 20 . [0025] During a pressure impact onto the measuring cell 1 the membrane 2 and the base body 3 respectively experience a compression on the side facing the medium and an elongation on the opposite side. In this case the elongation side and in particular the upper side 3 a of the base body is critical to the mechanical pressure limit of the measuring cell 1 , because with a cracked membrane 2 in fact no measurements are possible, but the medium yet cannot penetrate into the interior of the pressure measuring device. In order to improve the mechanical pressure limit of the measuring cell 1 the tensile stresses caused by the elongation must be reduced. [0026] This is achieved by an enlargement of the end portions 21 of the through holes 20 disposed at the upper side 3 a of the base body. However, the size of the through hole 20 itself should be made as small as possible in order to simplify the contacting of the pins 23 with the electrically conductive inner coating of the through hole 20 . The solution thus provides a bevel 22 as flat as possible which does not change the diameter of the through hole 20 itself, but increases or extends its exit opening 21 on the upper side 3 a in such a manner that thereby a significant reduction in the tensile stresses is achieved which ultimately leads to an improvement of the mechanical pressure limit of the entire measuring cell 1 . [0027] However, the spatial extent of this enlargement of the exit opening 21 is limited. On the one hand measuring cells of the type in question typically have a diameter of about 2 cm and on the other hand the through holes 20 must be located in the edge region of the measuring cell 1 in order not to affect the pressure-induced movement of the measuring cell 1 in the interior area. Consequently, it is useful to configure the exit openings 21 of the through holes 20 or their exit edges in an elliptical shape in order to achieve an enlargement by an extension in the tangential direction, while in the radial direction the enlargement can be made minimal. Here, the enlargement in the radial direction indeed may be dispensed with such that the smallest radius of the ellipse corresponds to the radius of the through hole 20 or the extension of the minor axis corresponds to the diameter of the through hole 20 . Studies on this have shown that with a ratio between the largest diameter and the smallest diameter or between the extension of the main axis and the extension of the minor axis of the ellipse of 2:1 an optimum between the spatial extension and a reduction of the tensile stresses is achieved. [0028] The elliptical shape of the exit edges in this case represents a preferred embodiment of the invention, however, in principle any oval shapes are conceivable. It is essential that by means of an enlargement of the through holes 20 their radius or circumference is increased. [0029] Although the exemplary embodiment shows a capacitive pressure measuring cell the invention can likewise be applied in resistive measuring cells with strain gauges when the base body is made of ceramic. The base body is often made of steel, but in some cases there are also applications where it is preferred to implement the base of ceramic. In this case there may be a need to implement the connections to the strain gauges through the ceramic body by means of through holes. Since here, too, the ceramic body experiences a pressure-induced longitudinal movement, the thereby occurring mechanical stresses can be minimized by providing the through holes respectively with a bevel and an oval or elliptical exit edge according to the invention, whereby as a result an improvement of the mechanical pressure limit is achieved.

The invention relates to a capacitive pressure measuring cell for detecting the pressure of a medium adjacent to the pressure measuring cell, comprising a ceramic elastic measuring membrane, the first side of which at least partially contacts the medium and the second side of which facing away from the medium comprises a measuring electrode, and a ceramic cylindrical basic body disposed opposite to the second side of the measuring membrane and comprising at least one counter electrode which forms a measuring capacitance with the measuring electrode.

The present application claims the filing benefit of co-pending U.S. Provisional Patent Application No. 60/862,914, filed Oct. 25, 2006, which is incorporated by reference herein in its entirety. TECHNICAL FIELD The present invention relates generally to machinery and mechanisms that operate in a cyclical manner, and more particularly to devices that facilitate cyclically operating such machinery and mechanisms. BACKGROUND Many machines and mechanisms operate in a cyclical manner. For example, rotating machinery such as turbines rotors, and reciprocating mechanisms such as paint shakers, exhibit cyclical motion. In use, these machines and mechanisms may be exposed to varying load conditions. However, many cyclically-operated machines and mechanisms are not able to accommodate varying loads while maintaining desired performance without substantial increases in power consumed. A need therefore exists for a simple, efficient system for driving cyclical machines and mechanisms, and for accommodating varying load conditions. SUMMARY A magnetic drive in accordance with the one aspect of the present disclosure overcomes the foregoing and other shortcomings of the prior systems for driving cyclical machines and mechanisms. In one embodiment, the magnetic drive includes an electrically conductive coil defining a bore and having first and second oppositely disposed ends. A magnetic member is movable from a first position outside the bore and adjacent the first end of the coil, through the bore to a second position outside the bore and adjacent the second end of the coil. The magnetic drive further includes a control that provides current to the coil to generate a magnetic field that interacts with the magnetic member. The control is able to reverse the direction of current through the coil and thereby act on the magnetic member as desired. In another aspect of the present disclosure, a counterbalance mechanism is provided for offsetting a load applied to a supporting structure. In one embodiment, the counterbalance includes a biasing member that is adapted to be coupled to a load support for reacting against a load applied to the load support. The counterbalance further includes a lever arm coupled to the biasing member. The lever arm is selectively positionable relative to the biasing member to vary a preload of the biasing member. The counterbalance may further include a pivot that cooperates with the lever arm and which is selectively positionable relative to the lever arm to vary the preload of the biasing member. In yet another aspect of the present disclosure, an apparatus for reciprocating a person includes a frame and a support platform that is constrained to move in a substantially vertical direction relative to the frame. The apparatus includes a counterbalance, as described above, with a biasing member coupled to the support platform and a lever arm coupled to the biasing member and the frame. The lever arm is selectively adjustable to vary a preload applied by the biasing member on the support platform. While various embodiments are discussed in detail herein, it will be understood that the invention is not limited to these embodiments. On the contrary, the invention includes all alternatives, modifications and equivalents as may be included within the spirit and scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention in sufficient detail to enable one of ordinary skill in the art to which the invention pertains to make and use the invention. FIG. 1 is a perspective view depicting an exemplary apparatus for reciprocating an infant support, with a cover of the housing shown in phantom. FIG. 2 is perspective view of the interior components of the apparatus of FIG. 1 . FIG. 3A is a left-side elevation view of the apparatus of FIG. 1 , with the support platform depicted in a raised position. FIG. 3B is a left-side elevation view of the apparatus of FIG. 1 , with the support platform depicted in a vertically centered position. FIG. 3C is a left-side elevation view of the apparatus of FIG. 1 , with the support platform depicted in a lowered position. FIGS. 4A-4F are cross-sectional elevation views of a magnetic drive used with the apparatus of FIG. 1 , depicting various positions of a magnetic member. FIG. 5 is a cross-sectional view taken along line 5 - 5 of FIG. 2 . DETAILED DESCRIPTION FIG. 1 depicts an exemplary cyclically operated apparatus 10 including an exemplary magnetic drive 12 and a load off-setting, or counterbalancing, device 14 in accordance with the principles of the present disclosure. In this embodiment, the apparatus 10 is configured for reciprocating an infant so as to soothe the infant in a manner similar to that described in U.S. Pat. No. 6,966,082, assigned to the assignee of the present invention and hereby incorporated by reference in its entirety. It will be understood, however, that the drive and load off-setting devices 12 , 14 described herein may alternatively be used in various other mechanisms, or may be used independently of one another. Referring to FIGS. 1 , 2 , and 5 , the apparatus 10 includes a frame 16 having first and second spaced frame members 18 , 20 interconnected by transverse beam members 22 , 24 . In the embodiment shown, the frame members 18 , 20 comprise substantially parallel, vertically-extending sidewalls 26 , 28 . The frame 16 may include adjustable feet or casters 30 to support the frame 16 above a floor surface, and the frame 16 , as well as other components of the apparatus 10 may be enclosed in a housing 32 . As shown in FIGS. 3A , 3 B, and 3 C, housing 32 may comprise a removable upper cover 32 a and a lower base portion 32 b. The apparatus 10 further includes a pair of spaced, parallel upper control arms 34 , 36 and a pair of spaced, parallel lower control arms 38 , 40 (see FIGS. 3C and 5 ) disposed between the vertically extending sidewalls 26 , 28 of the frame 16 . Respective first ends 34 a , 36 a of the upper control arms 34 , 36 and first ends 38 a , 40 a of the lower control arms 38 , 40 are pivotally coupled to the frame 16 by pinned connections 42 , 44 . The respective second ends 34 b , 36 b of the upper control arms 34 , 36 (see FIGS. 3A and 5 ) and first ends 38 b , 40 b of the lower control arms 38 , 40 are pivotally coupled to a support platform 46 by pinned connections 48 , 50 , whereby the upper control arms 34 , 36 and lower control arms 38 , 40 are movable with the support platform 46 to constrain movement of the support platform 46 in a substantially vertical direction. A seat mount 52 may be secured to the support platform 46 to facilitate coupling an infant support 54 to the support platform 46 , whereby the infant support 54 will be constrained for movement with the support platform 46 in a substantially vertical direction. Travel limiting stops, such as a lower limit bumper 56 ( FIG. 5 ) extending downwardly from support platform 46 , and an upper limit bumper (not shown) disposed between the lower control arms 38 , 40 and frame members 18 , 20 , may be provided to control the limits of travel of the support platform 46 . While the travel stops are shown and described herein as bumpers, it will be recognized that various other devices and methods may be used to limit the travel of platform 46 . While this embodiment is described as being configured to accommodate an infant support 54 , it will be recognized that the apparatus may alternatively be used to reciprocate a support for a range of persons, from youths to adults, in a manner similar to that described in co-pending U.S. application Ser. No. 11/257,877, assigned to the assignee of the present invention and hereby incorporated by reference in its entirety. In the embodiment shown, the frame members 18 , 20 , the upper control arms 34 , 36 , lower control arms 38 , 40 , and support platform 46 are formed from sheet metal that has been stamped or otherwise worked or machined to form the respective components of the apparatus. It will be recognized, however, that various other methods for forming the frame members 18 , 20 , upper control arms 34 , 36 , lower control arms 38 , 40 and support platform 46 may alternatively be used. For example, and not as limitation, the frame members 18 , 20 , upper control arms 34 , 36 , lower control arms 38 , 40 and support platform 46 may be formed by molding, casting, machining, or various other methods suitable for fabricating the respective components. With continued reference to FIGS. 1 and 2 , and referring further to FIG. 5 , the apparatus 10 may further include a tunable load-offsetting, or counterbalance, mechanism 14 for accommodating varying loads that may be applied to the support platform 46 . In the embodiment shown, the counterbalance mechanism 14 comprises a biasing member 60 disposed between the support platform 46 and the frame 16 . In this embodiment, the biasing member 60 is a spiral torsion spring having a first end 62 operatively coupled to the support platform 46 , and a second end 64 coupled to a spring lever 66 for selectively adjusting the preload, or initial deflection, of the spiral torsion spring 60 to correspond to a given load applied to the support platform 46 . The spring lever 66 comprises an elongate member having a first end 68 pivotally coupled to the support platform 46 , and a second end 70 cantilevered outwardly from the support platform 46 in a direction between the upper control arms 34 , 36 , the lower control arms 38 , 40 , and the vertically extending sidewalls 26 , 28 of the frame 16 . The second end 70 of the spring lever 66 is biased in a direction toward the lower control arms 38 , 40 by the spiral torsion spring 60 . The spiral torsion spring 60 is coupled to the support platform 46 by a pair of semi-circular disks 72 that are pivotally coupled to the support platform 46 by an arbor 74 around which the spiral torsion spring 60 is wound. With the first end 62 of the spiral torsion spring 60 connected to the disks 72 , an initial, constant preload of the spiral torsion spring 60 may be selectively adjusted by rotating the disks 72 relative to the support platform 46 and then securing the disks 72 at a desired angular position relative to the support platform 46 . In the embodiment shown, a plurality of apertures 74 spaced radially from the arbor are provided around the periphery of the disks 72 and the disks are secured to the support platform 46 by inserting a pin (not shown) through at least one of the apertures 74 and through a corresponding aperture 76 formed in the support platform 46 . The counterbalance mechanism 14 further includes an adjustable pivot, or fulcrum 80 , that is selectively positionable along the length of the spring lever 66 to thereby vary a preload of the platform without changing the initial deflection of the spiral torsion spring 60 . With the platform deflection substantially constant for all preloads, the system resonant frequency will also remain constant. In the embodiment shown, the fulcrum 80 comprises a roller supported on a shaft 82 extending between the vertical walls 26 , 28 of the first and second frame members 18 , 20 . The shaft 82 is received in corresponding slots 84 , 86 formed in the vertical walls 26 , 28 of the frame members 18 , 20 whereby the roller 80 may be maneuvered to various positions along the spring lever 66 by moving the shaft 82 along the slots 84 , 86 . To facilitate positioning the shaft 82 and roller 80 at a desired location along the slots 84 , 86 , pinion gears 88 are provided on the shaft 82 and are rotationally fixed to the shaft 82 at respective ends 90 of the shaft 82 that extend outwardly from the vertical walls 26 , 28 , as shown in FIG. 2 . The pinion gears 88 intermesh with corresponding rack gears 92 provided on the vertical walls 26 , 28 of the frame members 18 , 20 , whereby the position of the shaft 82 and roller 80 may be selected by turning the shaft 82 to cause the pinion gears 88 to move along the rack gears 92 to a desired location. Knobs 94 may be provided on the respective ends 90 of the shaft 82 to facilitate turning the shaft 82 and pinion gears 88 . With the spiral torsion spring 60 connected between the support platform 46 and the spring lever 66 , and with the spring lever 66 being pivoted about the arbor 74 of the spiral torsion spring 60 , a load applied to the support platform 46 is supported as a sprung mass by the spiral torsion spring 60 . Moreover, the static vertical position of the platform 46 and supported load relative to the frame 16 may be selectively adjusted by manipulating the shaft 82 to cause the roller 80 to move along the spring lever 66 , as described above. The support platform 46 and load, together with the spiral torsion spring 60 , therefore comprise a spring-mass system that exhibits a particular natural frequency. The support platform 46 and supported load may thus be moved upwardly and downwardly, supported on the spiral torsion spring 60 , while the upper control arms 34 , 36 and lower control arms 38 , 40 constrain the upward and downward movement in a substantially vertical direction. The natural frequency of the spring-mass system is related to the static deflection of the supported load upon the spiral torsion spring 60 . Accordingly, by adjusting the static vertical height of the support platform 46 relative to the frame 16 , using the roller 80 and spring lever 66 , the apparatus 10 may be adjusted or tuned to accommodate a range of loads supported on the support platform 46 while maintaining the natural frequency of the spring-mass system. Alternatively, the apparatus 10 may be adjusted with a given load to tune the spring-mass system to a desired natural frequency. Referring to FIGS. 2 , 5 , and 4 A- 4 F, in another aspect, the apparatus 10 may include a magnetic drive 12 mounted to the frame 16 and operatively coupled to the support platform 46 to move the support platform 46 upwardly and downwardly in a cyclical fashion. In the embodiment shown, the magnetic drive 12 includes an electric coil 100 comprising conductive wire wound to define a cylindrical barrel 102 having a central bore 104 with oppositely disposed first and second ends 106 , 108 . A magnetic member 110 is sized to be received within the bore 104 of the electric coil 100 whereby the magnetic member 110 may be moved from a first position outside the bore 104 and spaced from the first end 106 of the bore 104 (see FIG. 4A ), through the bore 104 , to a second position outside the bore 104 and spaced from the second end 108 of the bore 104 (see FIG. 4E ). In the embodiment shown, the magnetic member 110 comprises a stack of individual magnets 112 , however, it will be recognized that magnetic member 110 may alternatively comprise a single, unitary magnet. In another embodiment, all components of the drive 12 , except the magnetic member 110 , comprise non-ferrous materials When electric current is passed through the coil 100 , a magnetic field is generated that interacts with the magnetic member 110 . Depending upon the direction of current through the coil 100 , the magnetic field generated by the coil 100 may attract the magnetic member 110 , thereby pulling the magnetic member 110 in a direction into the bore 104 , or the generated magnetic field may repel the magnetic member 110 , effectively pushing the magnetic member 110 out from the bore 104 . When the magnetic member 110 is coupled to a moveable portion of a machine or device, the electric coil 100 can be selectively operated to impart motion to the device. To this end, the drive 12 may include a control 114 (see FIG. 1 ) operable to selectively provide current to the coil 100 and to selectively change the direction of the current, as needed, to move the magnetic member 110 through the bore 104 and thereby impart corresponding motion to the device. The magnetic drive 12 is particularly useful when the motion of the device to be moved is cyclical, such as the cyclical reciprocation of the apparatus 10 shown and described herein. In the embodiment shown, the magnetic member 110 is supported on a rod 116 extending downwardly from the support platform 46 and is positioned to be received through the bore 104 of the electric coil 100 as the support platform 46 is reciprocated in a substantially vertical direction as discussed above. In one embodiment, as the magnetic member 110 moves downwardly with the support platform 46 from a raised position (see FIG. 3A ) and approaches the first end 106 of the bore 104 (see FIG. 4A ), no current flows through the coil 100 and no magnetic forces cooperate with the magnetic field of the magnetic member 110 to induce or hinder motion of the magnetic member 110 . As the lower edge 118 of the magnetic member 110 enters the first end 106 bore of the bore 104 ( FIG. 4B ), current is provided to the coil 100 in a manner that generates a magnetic field that attracts the magnetic member 110 , causing the magnetic member 110 to be drawn into the bore 104 through the interaction of the magnetic fields of the magnetic member 110 and the coil 100 . The coil 100 remains energized as the magnetic member 110 moves into the bore 104 . Just before the lower edge 118 of the magnetic member 110 exits the second end 108 of the bore 104 ( FIG. 4C ), the coil 100 is de-energized to allow the magnetic member 110 to continue moving in a downward direction without the influence of any magnetic field from the coil 100 . Just after the lower end 118 of the magnetic member 110 exits the second end 108 of the bore 104 ( FIG. 4D ), the coil 100 is energized with current in a direction to generate a repulsing magnetic field in the coil 100 that pushes the magnetic member 110 further outside of the second end 108 of the bore 104 . Just as the upper end 120 of the magnetic member 110 exits the second end 108 of the bore 104 , the coil 100 is again de-energized and the magnetic member 110 is allowed to continue moving in a downward direction with no magnetic forces applied by the coil 100 . As the magnetic member 110 continues moving in a downward direction, the spiral torsion spring 60 is deflected by the corresponding downward movement of the support platform 46 until the spring force created by deflecting the spiral torsion spring 60 balances and gradually overcomes the downward inertial force of the loaded platform 46 , and the platform 46 begins to move in the opposite direction, upwardly away from the ground surface. Now, as the upper end 120 of the magnetic member 110 approaches the second end 108 of the bore 104 ( FIG. 4E ), no current is flowing through the coil 100 to create magnetic field lines that cooperate with the magnetic field lines of the magnetic member 110 . As the upper end 120 of the magnetic member 110 enters the second end 108 of the bore 104 ( FIG. 4F ), the coil 100 is energized to generate an attractive magnetic force that interacts with the magnetic field of the magnetic member 110 to thereby draw the magnetic member 110 into the bore 104 . The magnetic member 110 continues moving in an upward direction. Just prior to the upper end 120 of the magnetic member 110 exiting the first end 106 of the bore 104 , the coil 100 is de-energized to permit the magnetic member 110 to move upwardly, unhindered by any magnetic field generated by the coil 100 . Just after the upper end 120 of the magnetic member 110 exits the first end 106 of the bore 104 , the coil 100 is energized with current flowing in a direction that generates a repulsive force that interacts with the magnetic field of the magnetic member 110 , thereby pushing the magnetic member 110 further outside the first end 106 of the bore 104 . Just prior to the lower end 118 of the magnetic member 110 exiting the first end 106 of the bore 104 , the coil 100 is de-energized so that the magnetic field generated by the coil 100 is ceased. The magnetic member 110 continues to move in an upward direction with the support platform 46 until the forces acting on the support platform 46 due to inertia, gravity, spiral torsion spring 60 , and the load carried by the support platform 60 balance out, whereafter the support platform 46 and magnetic member 110 will begin to move downwardly toward the magnetic coil 100 . The control 114 continuously cycles current through the magnetic coil 100 in the manner described above and the motion described above is repeated so that the vertical reciprocating motion of the loaded platform 46 is maintained. The magnetic drive 12 described above is particularly useful when the driven system operates at its natural frequency because a minimum amount of force is needed to be generated by the magnetic drive 12 (to overcome friction losses, for example) whereby the cyclical motion may be maintained with the minimum force applied by the drive 12 . In the embodiment shown, the natural frequency of the loaded support platform 46 may be selectively adjusted by manipulating the roller 80 along the spring lever 66 . As the support platform 46 moves upwardly and downwardly in a reciprocating fashion at the system's natural frequency the magnetic member 110 will be caused to move into and out of the coil 100 as described above, whereby the magnetic drive 12 will maintain the substantially vertical reciprocating motion. Energization of the coil 100 can be automatically adjusted by the control 114 to accommodate variations in natural frequency. In the embodiment shown, the magnetic drive 12 includes a sensor 120 ( FIGS. 1 , 2 , and 5 ) that detects the position of the magnetic member 110 relative to the electric coil 100 and provides signals to the control 114 to energize and de-energize the electric coil 100 in the manner described above. In this embodiment, the sensor 120 comprises an optical position sensor 122 operatively coupled to the frame 16 , and a position indicating member 124 coupled to the support platform 46 (see FIG. 5 ). As the support platform 46 is reciprocated in a substantially vertical direction, the position indicating member 124 is caused to pass by the optical position sensor 122 . When the optical position sensor 122 senses the presence of the position indicating member 124 , signals are provided to the control 114 and the control 114 responds by energizing and de-energizing the electric coil 100 to operate in the manner described above. The control 114 may also be configured to automatically turn the apparatus on and off, by selectively energizing and de-energizing the electric coil 100 . For example, the control 114 may be configured to discontinue energization of the electric coil 100 after a predetermined period of continuous operation, or alternatively after a continuous period of non-use. The control 114 may also be configured such that energization of the electric coil 100 is ceased if no signal is received from the sensor 120 . With such a configuration, the vertical reciprocating motion of the support platform may be stopped simply by holding the platform at a fixed position, either near the uppermost point of travel, or the lowermost point of travel, to thereby prevent the sensor 120 from sending a signal to the control 114 . In a similar fashion, the control 114 may be configured to automatically energize the electric coil 100 at the instant the control receives a signal from the sensor 120 after a period of continuous non-use. When the magnetic drive 12 is used with a system that is configured to operate at its resonance frequency, such as the apparatus 10 described above, and the system further includes a control 114 as described above, a minimum amount of power is required to maintain operation of the system. Moreover, power is conserved by the ability of the control 114 to automatically turn the drive 12 on and off as needed. In an exemplary embodiment, an apparatus 10 for reciprocating an infant support 54 may be powered by six D-cell batteries and may operate continuously for more than approximately 120 hours. While the present invention has been illustrated by the description of an embodiment thereof, and while the embodiment has been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features discussed herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of the general inventive concept.

In one embodiment, a system for providing cyclic motion includes a magnetic drive having an electrically conductive coil defining a bore and a magnetic member movable through the bore. A control provides current to the coil and selectively reverses the direction of the current to move the magnetic member through the bore. In another embodiment, the system includes a counterbalance. The counterbalance includes a biasing member for reacting against a load applied to a support, and a lever arm coupled to the biasing member for varying a preload of the biasing member. In another embodiment, the magnetic drive and the counterbalance may be incorporated into an apparatus for reciprocating a person.

RELATED APPLICATIONS [0001] This application claims the benefit of prior Provisional Application Ser. No. 60/672,747 under 35 U.S.C. § 119 (e) and is hereby specifically incorporated by reference in its entirety STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not Applicable REFERENCE A “MICROFICHE APPENDIX” [0003] Not Applicable FIELD OF THE INVENTION [0004] This invention relates to an apparatus and method to monitor body temperature. BRIEF SUMMARY OF THE INVENTION [0005] An apparatus is provided that is made of a garment, at least one connector attached to the garment and an electronic transmission module connected to the connector. The connector is configured to receive an electronic transmission module. The electronic transmission module is programmed for wireless transmission. [0006] In one embodiment, the apparatus has a sensor positioned in the garment to obtain a temperature reading of a wearer of the garment. In one embodiment, the apparatus has a means to communicate the temperature reading to the electronic transmission module. In one embodiment, the apparatus has an electronic monitor to remotely receive and control electronic transmission for the electronic transmission module. [0007] In one embodiment, the electronic monitor has a device that conforms to the IEEE 802.15.4 Low-Rate Wireless Personal Area Standard. In one embodiment, the electronic transmission module has a device that conforms to the IEEE 802.15.4 Low-Rate Wireless Personal Area Standard. [0008] In one embodiment, the apparatus has a means to extend the electronic transmission range of the electronic transmission module. In one embodiment, the means to extend the electronic transmission range of the electronic transmission module is a range extender. The range extender has a device that conforms to the IEEE 802.15.4 Low-Rate Wireless Personal Area Standard. [0009] A connector is provided for making an electrical connection upon insertion of the connector into a corresponding receiver. The receiver has a plurality of connection pads. At least one of the connection pads of the receiver is connected to a power source. The connector is made of an extended body which has an insertion portion and non-insertion portion. The non-insertion portion has a plurality of solder points. The insertion portion has a plurality of connecting pads. The connecting pads on the insertion portion of the connector correspond to the connecting pads on the receiver. The connector is also made of at least one wire attached to the solder points, at least one trance connecting the at least one wire to at least one pad of the connector, and at least one looping trace connecting at least two connection pads of the connector. [0010] In one embodiment, the connector has two side members contiguous to the non-insertion portion the body. In an embodiment, the extended body is a printed circuit board. [0011] A method is provided for monitoring the body temperature of an individual. The method consists of the following steps: (a) placing a garment on an individual, wherein the garment has at least one sensor positioned to obtain a body temperature reading of the individual, wherein the garment has a connector configured to receive an electronic transmission module, wherein the electronic transmission module is programmed for electronic transmission; (b) securing an electronic transmission module into the connector which is configured to receive an electronic transmission module; (c) determining a body temperature from the sensor; (d) communicating the body temperature from the individual to an electronic monitor over a local wireless connection, wherein the electronic monitor is configured to remotely receive and control electronic transmission from the electronic transmission module; and (e) displaying the body temperature on the electronic monitor. [0012] In one embodiment, the method comprising the step of extending the electronic transmission range between the electronic transmission module and the electronic monitor with a range extender. BRIEF DESCRIPTION OF THE DRAWINGS [0013] FIG. 1 is a schematic rear view of a garment to monitor body temperature. [0014] FIG. 2 is a schematic top view of a garment to monitor body temperature. [0015] FIG. 3 is a side view of an electronic transmission module. [0016] FIG. 4 is a side view of an embodiment of a connector to receive an electronic module. [0017] FIG. 5 is a vertical top view of an electronic transmission module. [0018] FIG. 6 shows a schematic view of the assembly process involving an electronic transmission module inserted into a connector to receive an electronic module. [0019] FIG. 7 is a side view of an electronic monitor. [0020] FIG. 8 is a rear view of an electronic monitor. [0021] FIG. 9 is a front view of an electronic monitor. [0022] FIG. 10 is an enlarged view of the connector with a cut away portion showing the printed circuit board. [0023] FIG. 11 is a schematic front view of a range extender. [0024] FIG. 12 is a schematic side view of the range extender. [0025] FIG. 13 is a schematic top view of the range extender. [0026] FIG. 14 is a flow chart of the process to monitor body temperature. [0027] FIG. 15 is a flow chart of the internal workings of the electronic transmission module. [0028] FIG. 16 is a flow chart of the internal workings of the electronic monitor. DETAILED DESCRIPTION OF THE INVENTION [0029] Referring to FIGS. 1-9 , an embodiment of apparatus 1 to monitor body temperature is disclosed. The apparatus 1 is made of garment 2 , connector to receive an electronic transmission module 4 , electronic transmission module 6 , and electronic monitor 8 . [0030] Referring now to FIGS. 1-2 , garment 2 can be made of any material that will allow garment 2 to fit snuggly against the body of the wearer. Spandex is one example of a material, however other materials, such as a polyester elastane blend, may be used as desired by one of skill in the art. The material of garment 2 has elasticity properties that keep it close to the body of the wearer and such properties prevent garment 2 from stretching out and loosing its conformity to the body. [0031] In one embodiment, garment 2 has thermal sensors 12 sewn into garment 2 in such a way that the sensors 12 are held in close proximity to the body in the area of the underarms. In one embodiment, the sensors 12 are General Electric MA 100™ (GE Thermometrics, Inc. Billerica, Mass.) thermistors but any other sensors that are capable of measuring temperature changes can be used as desired by one of skill in the art. In an embodiment, garment 2 has two sensors 12 but any number of sensors can be used, including one, as desired by one of ordinary skill in the art. In one embodiment, sensors 12 are encased in garment 2 in the area of the underarms, however, sensors 12 may be placed at other locations where such sensors can obtain temperature reading as desired by one of skill in the art. [0032] Two connection wires 68 are connected to each sensor 12 . Connection wires 68 are encased in garment 2 in such a way that the each wire 68 travels from the sensor 12 to the connector 4 . In one embodiment, connection wires 68 travel and are encased along the seams of garment 2 . Garment 2 has antenna 3 appropriate to allow electronic transmission between electronic transmission module 6 and electronic monitor 8 . Antenna 3 is located in the collar of garment 2 . Antenna 3 is appropriate to the IEEE 802.15.4 Standard. [0033] Referring to FIGS. 1-2 and 10 , connector 4 is fixedly attached to garment 2 . In one embodiment, connector 4 is located in pocket 5 located near the collar of garment 2 . Connector 4 is attached to garment 2 by sewing connector 4 to garment 2 . Connector 4 has sewing holes 48 for such attachment (See FIG. 6 ). Other forms of attaching connector 4 may be used as desired by one of skill in the art. In one embodiment, connector 4 is attached to the top shoulder area of garment 2 near the collar but connector 4 can be attached to garment 2 anywhere as desired by one of ordinary skill in the art. Connector 4 is made of a sturdy, water resistant material such as a polymer or plastic but other materials may be used as desired by one of ordinary skill in the art. [0034] Referring now to FIG. 10 , a cut away view of connector 4 is shown. Connector 4 has the size and connection specifications of the male portion of the Micro SD. Other size and connection specification may be used as desired by one of ordinary skill in the art. Connector 4 does not contain an electronic data storage device as contained in the Micro SD. Instead connector 4 is configured to allow connector 4 to make an electrical connection with module 6 upon assembly of module 6 and connector 4 . Connector 4 has an extended body 50 that allows for the physical attachment of connector 4 to receiver 74 of module 6 . (See FIG. 6 ). In one embodiment, connector 4 has side members 52 that allow connector 4 to be attached to another object, such as garment 2 . Body 50 of connector 4 has an insertion portion 54 and a non-insertion portion 56 . Housing 70 covers and protects connector 4 ; however, the connection pads 60 of body 50 are not covered by housing 70 . Connection pads 60 are at the front connection edge of connector 4 . Housing 70 is made of a sturdy, water resistant material such as a polymer or plastic but other materials may be used as desired by one of ordinary skill in the art. Insertion portion 54 has eight connection pads or tabs 60 . Connection pads 60 are metallic connectors. In one embodiment, two of the connection pads 60 are connected by a looping trace 64 . Non-insertion portion 56 has solder points 58 . In one embodiment, five wires 68 are attached to five solder points 58 of non-insertion portion 56 . Traces 62 connect connection wires 68 to connection pads 60 . In one embodiment, connector 4 has snap tabs 76 that snap into snap notches 78 when connector 4 and module 6 are assembled thus reinforcing the assembly between connector 4 and module 6 . [0035] Referring to FIGS. 3 and 6 , module 6 has a receiver 74 . Receiver 74 is reversibly connected to module 6 . Receiver 74 has the size and connection specifications of the female portion of the Micro SD. Other size and connection specifications may be used as desired by one of ordinary skill in the art. Receiver 74 has eight connection pads that correspond to the connection pads 60 of connector 4 . Connection pads of receiver 74 are metallic. Receiver 74 is connected to power supply 20 . [0036] Referring again to FIG. 10 , body 50 is a printed circuit board 66 . In one embodiment, the printed circuit board 66 has five connection wires 68 permanently affixed to board 66 . Two wires 68 (one receiving wire and one transmitting wire) connect to one sensor 12 , two wires 68 (one receiving wire and one transmitting wire) connect to a second sensor 12 , and one wire which connects to antennae 3 that enables the electronic transmission module 6 to transmit information to electronic monitor 8 . The connection wires 68 are insulated except at the point of attachment to board 66 . Housing 70 encases wires 68 as wires 68 exit connector 4 so that moisture is kept out of the internal workings of connector 4 . [0037] Referring now to FIGS. 1-2 , 3 , 5 and 6 , apparatus 1 has an electronic transmission module 6 that connects to connector 4 . Electronic transmission module 6 contains a device 17 that conforms to the IEEE 802.15.4 Low-Rate Wireless Personal Area Standard or to the ZigBee Protocol. ZigBee is a published specification set of high level communication protocols designed to use small, low-power digital radios based on the IEEE 802.15.4 standard for wireless personal area networks. In one embodiment, electronic transmission module 6 is a ZigBee End Device. Pursuant to ZigBee Protocol, module 6 has the functional capabilities to communicate with monitor 8 . In one embodiment, module 6 cannot relay data from other ZigBee devices. In another embodiment, module 6 can relay data from other ZigBee devices, wherein module 6 serves as a ZigBee Router Device. [0038] Device 17 of module 6 contains a radio and a microprocessor which contains the code that enables sensor 12 to constantly measure the temperature of the individual wearing garment 2 upon assembly of module 6 into connector 4 . The microprocessor within device 17 also contains the code that enables the radio of device 17 to function within the specification set forth by the ZigBee 1.0 specifications and subsequent developed versions of such specifications. Electronic transmission module 6 has a power supply 20 (See FIG. 3 ). In one embodiment, power supply 20 is a battery. [0039] Upon assembly of module 6 and connector 4 , eight connection pads 60 of connector 4 line up and connect to eight connection pads located in receiver 74 of module 6 . One of the pads located inside receiver 74 is connected to the power supply 20 of module 6 . This connection is accomplished by a printed circuit board trace between such connection pad inside receiver 74 and power supply 20 . The terminal of power supply 20 is affixed to a point on the printed circuit board inside module 6 . This physical connection allows the electrical current from the power supply 20 to flow from the power supply 20 to such connection pad inside receiver 74 . The electrical current then passes from the pad inside receiver 74 to the corresponding connection pad 60 on connector 4 . The corresponding connection pad 60 on connector 4 has a looping trace 64 connecting such pad 60 to a second connection pad 60 located on connector 4 , thus connecting second connection pad 60 and the corresponding pad inside receiver 74 connected to power-in trace creating a power circuit that allows all electronic components of the module 6 to operate. [0040] Upon assembly of the module 6 and connector 4 , an electrical connection turns module 6 “on” and module 6 sends out a signal to electrical monitor 8 (described below). The electrical connection also enables module 6 to communicate with sensors 12 directing sensors 12 to measure the temperature of the body of the wearer of garment 2 . The electrical connection also enables module 6 to make the connection to antenna 3 which allows the module 6 to transmit electronic communication to the electronic monitor 8 . [0041] Referring now to FIGS. 7-9 , apparatus 1 has an electronic monitor 8 that is configured to remotely receive and control electronic transmission from electronic transmission module 6 . Electronic monitor 8 has a radio that conforms to the IEEE 802.15.4 Low-Rate Wireless Personal Area Standard. Electronic monitor 8 has a microprocessor that operates in accordance with ZigBee 1.0 specifications and subsequently developed versions of such specifications. The ZigBee specifications dictate the communications received and controlled by electronic monitor 8 . [0042] Monitor 8 serves as a Coordinator Device in the ZigBee Mesh Network. Electronic monitor 8 will dictate the frequency of temperature readings and transmissions from the electronic transmission module 6 . Monitor 8 has frequency control option 27 . Electronic monitor 8 contains code that allows the user of apparatus 1 to setup parameters of temperature profiles that trigger audible and visible alarms set off by the electronic monitor 8 when those parameters are met or exceeded. Monitor 8 has alarm control option 26 . Electronic monitor 8 may also contain code that initiates other message activities over the public or a private telephone network, radio or intercom network as well as create messages for electronic communications such as email. [0043] Monitor 8 contains code that allows the temperature readings to be recorded to flash memory for later retrieval through a port or by removal of the flash device. In one embodiment, a USB port 36 is used to retrieve temperature readings but any other port can be used as desired by one of ordinary skill in the art (See FIG. 7 ). [0044] Monitor 8 may communicate with more than one electronic transmission module 6 inserted into the connector 4 of two garments 2 within its Mesh Network. Referring to FIG. 9 , monitor 8 has two temperature reading displays 38 . Monitor 8 has two charging circuits 34 for recharging electronic transmission module 6 (See FIG. 9 ). In one embodiment, monitor 8 has an alarm suspend 30 and clock 40 . Monitor 8 has a commercial plug attachment 28 built into it allowing the user to plug the monitor 8 into commercial power. [0045] Referring now to FIGS. 11-12 , in one embodiment, apparatus 1 has a range extender 10 that extends the electronic transmission range of the electronic transmission module 6 . If module 6 and monitor 8 exceed the operable range, appropriate to the IEEE 802.15.4 Standard, the range extender 10 can be used to extend the range and allow the apparatus 1 to function. The range extender 10 has a radio 16 that conforms to IEEE 802.15.4 Low Rate Wireless Personal Area Standard and range extender 10 has a microprocessor 18 coded with ZigBee 1.0 specifications and subsequently developed specifications. The range extender 10 serves as a ZigBee router. Range extender 10 is connected to a power supply through outlet 19 and has antenna 21 . Antenna 21 is connected to extender 10 by hinge 23 . Antenna 21 is appropriate to the IEEE 802.15.4 Standard. The radio in the range extender 10 follows the ZigBee protocols under the “Router” functional specification. The range extender 10 allows electronic transmission module 6 to be bridged to electronic monitor 8 if it is out of range or if some other force precludes the proper communication between the electronic transmission module 6 and electronic monitor 8 . [0046] Referring now to FIG. 14 with reference to FIGS. 1-10 , the overall process of monitoring body temperature of an individual is provided. Module 6 is removed from charging circuit or unit 34 . Module 6 is snapped into connector 4 . Upon assembly, module 6 communicates with monitor 8 and module 6 begins operating according to firmware or code. Module 6 causes sensor 12 to return a reading of resistance which is converted to a temperature equivalent. Module 6 transmits the temperature reading to monitor 8 which displays or announces the temperature. Monitor 8 compares the display with a potentially pre-set alarm point. If the pre-set alarm point is reached, monitor 8 will sound an alarm and/or vibrate. Monitor 8 records the temperature data in a memory buffer which can be downloaded into other storage devices via the port on monitor 8 . Module 6 is removed from the connector 4 and re-attached to charging circuit or unit 34 on monitor 8 for charging. The process can be started again once module 6 is recharged. [0047] Referring now to FIG. 15 with reference to FIGS. 1-10 , the internal workings of the electronic transmission module 6 are provided. Module 6 is snapped into connector 4 which has looping trace 64 that enables module 6 to operate. Module 6 sends out a beacon request to announce its presence to monitor 8 . Module 6 sends its MAC address to monitor 8 for verification. Module 6 receives validation to operate on network. Module 6 launches operating firmware routine for temperature measurement. Firmware causes printed circuit board components to release electrical current into one wire of sensor 12 . Sensor 12 changes size based on the surrounding temperature. The size change of sensor 12 creates measurable electrical resistance. The resistance is measured as the electrical current is returned to module 6 through the second wire of the sensor. The electrical resistance is measured by virtue of an ADC port on the printed circuit board. The ADC value is compared to an “R to T” chart for sensor 12 . The corresponding temperature found in the “R to T” chart is transmitted to monitor 8 via the 802.15.4 radio. [0048] Referring now to FIG. 16 with reference to FIGS. 1-10 , the internal workings of the electronic monitor 8 are provided. Monitor 8 is plugged into commercial power and/or batteries are installed. After module 6 is charged, module 6 is removed from charging circuit 34 and snapped into connector 4 . Alarm values are set via adjustment buttons on the outside of monitor 8 . Monitor 8 establishes connection with module 6 . The firmware causes the 802.15.4 radio to accept communication that conforms to the correct protocol. The monitor 8 receives data from module 6 . The firmware causes the display to show the corresponding value. Monitor 8 displays the temperature value. An alarm is sounded if the display values are equal to or greater than the alarm values. The display values are recorded in a memory buffer for later retrieval. An outside storage device can be attached to the port on monitor 8 to extract the stored data. [0049] Although the foregoing detailed description has been set forth in some detail by way of illustration and example for purposes of clarity of understanding, it will be obvious that certain changes and modifications can be made within the full scope of the invention.

An apparatus is provided which is made of a garment having at least one connector to receive an electronic transmission module and an electronic monitor configured to remotely receive and control electronic transmission from the electronic transmission module. The garment includes a sensor to detect the temperature of the wearer. This invention also provides a connector for making an electrical connection. This invention also provides a method for monitoring the body temperature of the wearer.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the hunting of wild game and, in particular, to a portable device for the hoisting and skinning of wild game in the field. 2. Description of the Related Art Hunters have hunted, killed and skinned wild game since before recorded history. The skinning and dressing of game in the field is best done when the game is hoisted off of the ground into a hanging position with either the head of the game elevated and the rear legs hanging down, or with the rear legs elevated and the head and the front legs hanging down. Game can be long and heavy, so it is necessary that the game be hoisted to a sufficient height to enable a person to manipulate the game as necessary to remove the skin without the game dragging on the ground. Numerous patents disclose vehicle mounted, tree depending and free standing game hoists. Game hoists are generally used in remote areas and have to be transported to the location of use. Portability is a key factor for game hoists to be used in the field. Tree depending game hoists utilize a tree for structural support, while free standing game hoists generally require a rigid support which may add to the weight of the device. Vehicle depending game hoists are generally similar to free standing devices but are adapted to be supported by a trailer hitch or other component of the motor vehicle. Several inventions are known to those skilled in the art for hoisting killed game into position for skinning. U.S. Pat. No. 5,562,534 (“the '534 patent”) discloses a game hoist having a dual-purpose winch. The '534 patent also discloses a first pulley used with the winch for hoisting game and a second pulley used with the winch for skinning game. After the game is hoisted to a hanging position, the game is secured in the hanging position and the winch is used, in combination with a second pulley, to pull the skin of the game. The '534 patent is a tree depending hoist and requires the user to find a tree having a trunk suitable for receiving straps or chains used to secure the winch, the first pulley and the second pulley. Tree depending game hoists generally require a tree having an uninterrupted section of trunk with no limbs and a diameter within a certain range. A problem with tree depending hoists like the one disclosed in the '534 patent is that a ladder may be required in order to secure the hoist to the tree at a height sufficient to prevent hoisted game from contacting the ground during skinning process. Another problem with tree depending game hoists like the one disclosed in the '534 patent is that the second pulley is secured to the trunk of a tree instead of being strategically positioned directly underneath the hoisted game. This may cause the game to be pulled in a direction other than straight down, and the game may swing or spin during or after the skinning process. Also, the game hoist disclosed in the '534 patent may not be usable if the tree does not have a extended portion of suitable diameter trunk near the ground that is without limbs or other naturally occurring features that may prevent the attachment and use of the lower pulley. Another problem with game hoists like the one disclosed in the '534 patent is the requirement of a second pulley. The user must unthread the strap or cable from the first pulley after hoisting the game, and then thread the strap or cable around the second pulley for skinning the game. This manipulation of the strap or cable may be time consuming and difficult, especially in cold weather when the manual dexterity of the user's hands is impaired by cold or by gloves. Also, the requirement of the second pulley adds unnecessary weight to the device. Another problem with game hoists like the one disclosed in the '534 patent is that it supports only a single game, and will not accommodate multiple game. Hunters that hunt in groups would each need to bring their own individual game hoist or they would have to skin one game at a time while other game lay on the ground attracting insects or scavengers. Another problem with game hoists like the one disclosed in the '534 patent is that it does not assist the user in loading skinned game into a truck or onto a motor vehicle unless the vehicle can be positioned under the tree to which the device is secured. What is needed is a game gallows for hoisting and skinning game that is more portable for easier transport to the field. What is needed is a game gallows that allows the user to hoist and skin the game without removing the strap or cable from a hoisting pulley and rethreading the strap or cable over a skinning pulley. What is needed is a game gallows for simultaneously hoisting and skinning multiple game. What is needed is a game gallows that is suitable for loading game into the bed of a truck or onto a motor vehicle. SUMMARY OF THE INVENTION The present invention provides a device for skinning game that overcomes the disadvantages in the prior art. The present invention provides a game gallows for skinning game that is suitable for being supported by a vehicle or for use as a free standing gallows. The present invention provides a game gallows that allows the simultaneous processing (dressing or skinning) of multiple game. The present invention provides a game gallows that does not require the user to remove and rethread straps or cables around different pulleys. The present invention includes a support and a rotatable hanger assembly. The hanger assembly is designed to accommodate a plurality of killed game and has a generally vertical axis of rotation. The support has a pulley arm pivotally coupled to the support for rotation in a generally vertical plane. In one embodiment, the first leg of the pulley arm is pivotally coupled to the support, and the second leg of the pulley arm extends generally perpendicular from the first leg and is coupled to a pulley. The first leg of the pulley arm also has a winch for pulling a strap or cable that passes around the pulley into tension. The pulley arm pivots between a superior position, with the second leg and the pulley secured into a position near the hanger assembly, and an inferior position, with the second leg and the pulley secured into a position near the ground. The winch operatively engages a strap or pulley that is threaded around the pulley for pulling in a generally vertical direction: upwardly when the second leg and pulley are secured into the superior position near the hanger assembly (for hoisting), and downwardly when the second leg and pulley are secured into the inferior position near the ground (for skinning). With the pulley arm in the superior position, the winch pulls the strap or cable to hoist game into a hanging position for hanging the game onto one of the hangers on the hanger assembly. With the pulley arm in the inferior position, the winch pulls the strap or cable to skin a game that is secured to and hanging on a hanger. BRIEF DESCRIPTION OF THE DRAWINGS So that the above recited features and advantages of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof that are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are, therefore, not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. FIG. 1 is a perspective view of the game gallows of the present invention with the pulley arm in the hoisting position. FIG. 2 is a perspective view of the game gallows of the present invention with the pulley arm in the skinning position. FIG. 3 is a perspective view of the game gallows of the present invention with the pulley arm rotating from the hoisting position to the skinning position. FIG. 4 is an elevational view of the dismembered killed game being hoisted to a hanging position using the game gallows of the present invention. FIG. 5 is an elevational view of a second dismembered game being coupled to an open hanger after the first dismembered game awaits skinning. FIG. 6 is an elevational view of the game gallows of the present invention with the pulley arm in the skinning position and the strap coupled to the skin of a game. FIG. 7 is an elevational view of the game gallows of the present invention with the winch being used to skin a game. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a perspective view of one embodiment of the game gallows of the present invention. The embodiment of the game gallows 10 depicted in FIG. 1 comprises a support 12 having a first end 14 and a second end 16 , a rotatable hanger assembly 20 that is rotatably coupled to the first end 14 of the support 12 . The hanger assembly 20 has a plurality of radially outwardly extending hangers 22 , each of which can support a game. Each hanger 22 has a chain plate 23 coupled along the top of the hanger 22 , and each chain plate 23 has a link channel 25 of a width slightly greater than the diameter of the links of the chain 24 that is secured to the chain plate 23 . The chain 24 can be secured to a game (not shown) by inserting a link of the chain 24 into the link channel 25 of the chain plate 23 as shown on FIG. 1 . In the embodiment shown in FIG. 1 , a base 40 is coupled to the second end 16 of the support 12 . FIG. 1 shows a base 40 having a plurality of radially outwardly extending legs 42 that generally lie in a horizontal plane. Preferably, the legs 42 may have a one to three degree downwardly slope from center to end to provide additional stability when placed upon soft ground. The embodiment of the game gallows 10 is depicted in FIG. 1 further comprises radially outwardly telescoping leg extenders 43 . Deployment of the leg extenders 43 , as shown in FIG. 1 , improves stability of the game gallows 10 . The embodiment of the game gallows 10 depicted in FIG. 1 further comprises a pulley arm 50 having a first leg 52 and a second leg 54 , the first leg 52 being pivotally coupled to the support 12 at a pivot 60 . The first leg 52 of the pulley arm 50 is also coupled to a winch 62 having a strap 64 rolled onto a spool. The second leg 54 of the pulley arm 50 extends generally perpendicular to the first leg 52 and is coupled to a pulley 56 around which the strap 64 is threaded. “Strap,” as that term is used herein, refers to a strap, wire, rope, cable or any other elongated flexible tether suitable for use with a winch. The winch 62 may be any suitable means of reeling in and storing, unreeling and feeding out, and locking strap. Alternately, a winch having a gear sprocket can utilize a chain. A Fulton Performance Products, Inc. (of Mosinee, Wis.) Trailer Winch model T903, 900 pound capacity is preferred. The pulley 56 shown in FIG. 1 comprises a tubular hollow shaft rotatable on an axle received into its hollow interior. The support 12 may have a plurality of foot pegs 70 welded onto the support 12 and generally perpendicular to the support 12 . The pegs 70 are located between the pivot 60 and the second end 16 of the support 12 . The foot pegs 70 enable the user to climb the support 12 to reach the hangers 22 of the hanger assembly 20 or the chains 24 hanging on the hangers 22 . The game gallows 10 further comprises retainer 80 for engaging the pulley arm 50 and securing the pulley arm in the hoisting position. The game gallows 10 further comprises a lower retainer 81 for engaging the pulley arm 50 and for securing the pulley arm 50 in the skinning position. The upper retainer 80 allows the pulley arm 50 to be secured in the hoisting position ( FIG. 1 ), and the lower retainer 81 allows the pulley arm 50 to be secured in the skinning position ( FIG. 2 ). As shown in FIGS. 1 and 2 , each hanger 22 may include a chain 24 . A hanging tool, such as a collar or a gambrel (not shown), is fitted or secured around the head or coupled to the rear legs of a game (not shown), respectively, and is used to couple the game to the hook 26 on the strap 64 to hoist the game into position using the winch 62 . FIG. 3 is a perspective view of the game gallows 10 of the present invention with the pulley arm 50 rotating from the hoisting position (shown in FIG. 1 ) to the skinning position shown in FIG. 2 . The pulley arm 50 is shown in FIG. 3 to be rotating about the pivot 60 away from the upper retainer 80 in a clockwise direction, and will continue to rotate until it reaches the skinning position shown in FIG. 2 and is received into and secured by the lower retainer 81 (shown in FIG. 2 ). FIG. 4 is an elevational view of a first dismembered game 92 being hoisted to a hanging position using the game gallows 10 of the present invention. The game 92 is secured to the strap 64 by the hook 26 that is coupled to the end of the strap 64 . The hook 26 engages the collar 91 that is secured around the neck of the game 92 , and the winch 62 is operated to reel in and pull tension in the strap 64 that is threaded over the pulley 56 . FIG. 5 is an elevational view of the first dismembered game 92 being coupled to the hanger assembly 20 of the game gallows 10 for skinning. The first dismembered game 92 is lifted high enough to allow the user to pull the chain 24 through the collar 91 and to insert a link of the chain 24 into the link channel 25 of the chain plate 23 as shown in FIG. 5 . Once the weight of the first dismembered game 92 is supported by the chain 24 , the hanger 22 and the hanger assembly 20 , the hook 26 and the strap 64 can be disengaged from the collar 91 . The hanger assembly 20 can then rotate to remove the killed game 92 from the lift zone. FIG. 6 is an elevational view of one embodiment of the game gallows 10 of the present invention with a second dismembered game 93 secured to the hanger assembly 20 and the pulley arm 50 rotated to the skinning position. The first dismembered game 92 is shown to have been moved to the right by rotation of the hanger assembly 20 . The strap 64 and hook 26 are coupled to the skin of the second dismembered game 93 using a collar 91 . The hook 26 and the strap 64 are secured to a flap 95 of the skin of the second dismembered game 93 using a skinning tool 94 . The operation of the winch 62 reels in and produces tension in the strap 64 enabling the user to forcibly pull the flap 95 and skin the second dismembered game 93 . FIG. 7 is an elevational view of one embodiment of the game gallows 10 of the present invention with the winch 62 being used to skin the second dismembered game 93 . The flap 95 of the second dismembered game 93 grows larger as the winch 62 is turned to pull the strap 64 and skin the second dismembered game 93 . It will be understood from the foregoing description that various modifications and changes may be made in the preferred and alternative embodiments of the present invention without departing from its true spirit. For example, the game gallows is shown in the drawings as free standing, but is easily adapted for being tree-depending or vehicle depending. For tree depending, the support 12 may be secured to a tree or post using straps, bands or clamps, or any of the other devices used to secure items to trees or posts that are known in the prior art. The device disclosed above and shown in FIGS. 1–7 can be adapted to make a tree depending game hoist by providing an offset between the axis of the rotating hanger assembly 20 and the support 12 . For vehicle depending, the radially outwardly extending leg 42 (see FIG. 1 ) that is opposite the pulley arm 50 may be inserted into a receptacle, such as a standard 1½ inch square or 2 inch square standard trailer hitch. This enables the user to winch a game, couple the game to a hanger 22 , and rotate the hanger assembly 20 to position the game over the bed of a truck or other cargo surface of a vehicle, then use to winch 62 to lower the game onto the truck bed or cargo surface. This description is intended for purposes of illustration only and should not be construed in a limiting sense. The scope of this invention should be determined only by the language of the claims that follow. The term “comprising” within the claims is intended to mean “including at least” such that the recited listing of elements in a claim are an open group. “A,” “an” and other singular terms are intended to include the plural forms thereof unless specifically excluded.

The present invention discloses portable game gallows for hoisting and skinning multiple game. The portable game gallows includes a winch having a strap or cable that can be used to raise game into position for hanging on a rotating tree and for skinning game that is hung from the tree. The present invention discloses a dual purpose pulley that can be locked into a first position for hoisting a game or a second position for skinning a game.

BACKGROUND OF THE INVENTION The present invention relates generally to the art of magnetic resonance. It finds particular application to magnetic resonance imaging receiver coil systems having detachable, relocatable, and/or interchangeable sections. It will be appreciated, however, that the present invention is also applicable to the examination of other portions of the human anatomy and to the imaging or spectroscopic examination of non-human subjects or other objects, materials, and so forth. Conventionally, magnetic resonance imaging systems generate a strong, uniform, static magnetic field in a free space between poles or in a bore of a magnet. This main magnetic field polarizes the nuclear spin system of an object to be imaged placed therein. The polarized object then possesses a macroscopic magnetic moment vector pointing in the direction of the main magnetic field. In a superconducting main annular or bore magnet assembly, the static magnetic field B 0 is generated along a longitudinal or z-axis of the cylindrical bore. To generate a magnetic resonance signal, the polarized spin system is excited by applying a magnetic resonance signal or radio frequency field B 1 perpendicular to the z-axis. The frequency of the magnetic resonance signal is proportional to the gyromagnetic ratio γ of the dipole(s) of interest. The radio frequency coil is commonly tuned to the magnetic resonance frequency of the selected dipole of interest, e.g., 64 MHZ for hydrogen dipoles 1 H in a 1.5 Tesla magnetic field. Typically, a radio frequency coil for generating the magnetic resonance signal is mounted inside the bore surrounding the sample or patient/subject to be imaged. In a transmission mode, the radio frequency coil is pulsed to tip the magnetization of the polarized sample away from the z-axis. As the magnetization precesses around the z-axis back toward alignment, the precessing magnetic moment generates a magnetic resonance signal which is received by the radio frequency coil in a reception mode. For imaging, a magnetic field gradient coil is pulsed for spatially encoding the magnetization of the sample. Typically, the gradient magnetic field pulses include gradient pulses pointing in the z-direction but changing in magnitude linearly in the x, y, and z-directions, generally denoted G x , G y , and G z , respectively. The gradient magnetic fields are typically produced by a gradient coil which is located inside the bore of the magnet and outside of the radio frequency coil. Conventionally, when imaging the torso, a whole body radio frequency coil is used in both transmit and receive modes. By distinction, when imaging the head, neck, shoulders, or an extremity, the whole body coil is often used in the transmission mode to generate the uniform excitation field B 1 and a local coil is used in the receive mode. Placing the local coil surrounding or close to the imaged region improves the signal-to-noise ratio and the resolution. In some procedures, local coils are used for both transmission and reception. One drawback to local coils it that they tend to be relatively small and claustrophobic. One type of local frequency coil is known as the “birdcage” coil. See, for example, U.S. Pat. No. 4,692,705 to Hayes. Typically, a birdcage coil is cylindrical and comprises a pair of circular end rings which are bridged by a plurality of equi-spaced straight segments or legs. Birdcage head coils are capable of providing a high signal-to-noise ratio (SNR) and achieving readily homogeneous images. Birdcage coils are widely used for functional MRI (fMRI) and other applications. Birdcage coils, however, are not without their disadvantages. Since, generally, the SNR and thus image quality increases with decreasing distance between the receiver coil and the volume being imaged, birdcage coils are generally designed so that they will be located very close to the subject's head, particularly since fMRI applications require the ability to extract small signals (e.g., reported to be as low as about 2-5% at 1.5 T). As the name implies, birdcage coils are also closed or cage-like in nature and thus restrict access to the subject's face and head. This results in a lack of space for placement of stimulation devices that would be desirable for fMRI experiments. Stimulation devices are devices constructed to stimulate a specific neural function of a subject, the response to which is sought to be observed through imaging the appropriate region of the brain. Such stimulators may emit, for example, mechanical, electrical, thermal, sound, or light signals designed to stimulate the neural activity of interest. The neural activity is induced by sensory stimuli, such as visual, auditory, or olfactory stimuli, taste, tactile discrimination, pain and temperature stimuli, proprioceptive stimuli, and so forth. Since the birdcage design is close fitting and not particularly open in nature, many such stimulation experiments must be performed in a manner that is suboptimal, if at all. For example, the use of a birdcage coil might preclude, due to space constraints, the use of an auditory stimulation device, such as a headphone set. Likewise, since bars are placed over the face, and in some instances directly over the eyes, birdcage coils are particularly disadvantageous for eye-tracking experiments or other visualization experiments. Another problem with birdcage coils is that the design limits access to the patient, e.g., for therapeutic, physiological monitoring, and patient comfort purposes. Access may be needed, for example, to monitor physiological functions, such as oxygen levels, or to perform interventional medicine or use life-support devices, such as ventilator tubes, tracheotomy tubes, etc., while imaging a patient. Drug delivery, contrast agent delivery, and delivery of gases such as anesthetizing gases, contrast-enhancing gases, and the like, also require patient access. Also, it is also often desirable to enhance patient comfort through the use of patient comfort devices. However, the proximity of the axial segments to one another and to the head of the patient impairs such practices. Yet another problem with birdcage head coils is their claustrophobic effect on patients. Many pediatric and adult patients already experience claustrophobic reactions when placed inside the horizontal bore of a superconducting magnet. Placement of a close-fitting head coil having anterior legs which obstruct the direct view of the patients further adds to their discomfort. Attempts to reduce the discomfort have been made, for example, through the use of illumination inside the magnet bore, air flow, and the use of reflective mirrors. Although claustrophobic reactions and discomfort are sometimes reduced somewhat by such measures, claustrophobia can still be problematic. Birdcage coils are circularly polarized. Removing or altering the spacing of the legs adjacent the face alters the symmetry and can degrade performance. Other types of localized coils include a phased array of smaller surface coils. In this manner, a greater SNR (that increases in proportion to the number of elements) than birdcage design can be achieved. For fMRI applications, flexible coil arrays can be wrapped around the head. However, these so-called flex-wrap designs are lacking in the spatial openness necessary for stimulation studies, interventional imaging, and the accommodation of therapy devices. Furthermore, it is difficult to achieve uniform placement of coils, both as between different subjects and for repeat studies of the same subject. The present invention provides a new and improved localized RF coil that overcomes the above-referenced problems and others. SUMMARY OF THE INVENTION In one aspect, the present invention provides an radio frequency (RF) coil system for magnetic resonance imaging of one or more regions of a subject. The coil system includes a first coil section comprising one or more conductive coils in a first nonconductive housing, and a second coil section comprising one or more conductive coils in a second nonconductive housing, wherein the first and second coil sections are configured to be inherently decoupled or have minimal coupling. The coil system further comprises one or more fasteners removably and movably joining the housings of the first and second coil sections. In a further aspect, the present invention provides a magnetic resonance imaging system comprising a main field magnet for generating a temporally constant magnetic field along a main field axis and an RF coil system. The RF coil system includes a first coil section configured for maximum or predominant field sensitivity along a first axis perpendicular to the main magnetic field axis, a second coil section configured for maximum sensitivity along a second axis perpendicular to the first and main magnetic field axes, and a fastening system for selectively fastening the first and second coil sections on opposite sides of a region of interest for quadrature reception of resonance signals emanating from the region of interest. In yet a further aspect, the present invention provides a magnetic resonance method comprising the steps of establishing a polarizing magnetic field in a region of interest; exciting resonance of selected dipoles in the region of interest to generate magnetic resonance signals; and concurrently receiving the magnetic resonance on one side of the region of interest with a first linear coil having a maximum sensitivity along a first axis orthogonal to the polarizing magnetic field, and on an opposite side of the region of interest with a second linear coil having a maximum sensitivity along a second axis orthogonal to both the polarizing magnetic field and the first axis. One advantage of the present invention is that it increases spatial openness around the subject. Another advantage resides in its ability to easily select the desired coverage. Another advantage resides in improved accommodation for stimulation devices, such as the type used for fMRI experiments, and coil placement or removal options to maximize patient comfort. Another advantage resides in improved accommodation of patient comfort devices. Another advantage of the present invention is that detaching coil sections still permit the remaining coil sections to be operational. Another advantage of the present invention is that it accommodates life support or therapeutic devices such as ventilator tubing, tracheotomy tubes, immobilization collars, etc. Another advantage of the present invention is that it provides detachable and/or relocatable coil sections matched to fMRI experiments, such as auditory or visual fMRI experiments. In addition to providing openness in the space around the subject's head that matches the requirements of the particular fMRI procedure, data acquisition throughput is increased in that the region of interest can be tailored to the appropriate region of the brain, i.e., the region or regions containing the neural activity of interest. Another advantage of the present invention is that aliasing can be reduced by reduction of coverage of the excitation area. Yet another advantage of the present invention is that coil concentration can be increased for areas of interest or extended to areas not well covered by the current coil designs. Another advantage is that switching between different fMRI experiments and/or different stimulation equipment, such as between vision and auditory experiments, can be more readily performed. Still another advantage resides in its ability to monitor relatively small signals, such as in blood oxygen level dependent contrast (BOLD) studies. Yet another advantage of the present invention is that it allows a technologist to readily position and lock non-imaging devices. Still another advantage of the present invention is that it is readily adaptable to time-saving techniques where temporal resolution is desired. Still another advantage of the present invention is its adaptability to subjects having different body shapes and sizes, including subjects for whom the conventional head coil designs might provide an ill fit. Yet another advantage of the present invention is that it is can also be used for interventional imaging. Another advantage is that it allows addition, removal, and exchanging of coils. Other advantages include the improved physiological monitoring, improved drug and contrast agent delivery, and improved delivery of gases such as anesthetizing gases or contrast-enhancing, e.g., hyperpolarized, gases. Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS The invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating preferred embodiments and are not to be construed as limiting the invention. FIG. 1 is a diagrammatic illustration of a magnetic resonance imaging system apparatus including a coil construction in accordance with the present invention; FIGS. 2 and 3 are functional block diagram illustrating alternative embodiments of data acquisition circuitry for use with the RF coil system in accordance with the present invention; FIG. 4 illustrates a first exemplary embodiment of a coil construction according to the present invention; FIG. 5 shows the coil conductors of the embodiment of FIG. 4; FIG. 6 illustrates a manner in which the movable coil section of FIG. 5 can be relocated; FIG. 7 illustrates a second exemplary embodiment of a coil construction according to the present invention; FIG. 8 shows the coil conductors of the embodiment of FIG. 7; FIG. 9 illustrates an exemplary manner in which the movable coil section of FIG. 7 can be relocated; and FIG. 10 illustrates a coil system in accordance with the present invention comprising multiple interchangeable coil sections. FIG. 11 illustrates an alternative embodiment of a coil section of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1, a plurality of primary magnetic coils 10 generate a uniform, temporally constant magnetic field B 0 along a longitudinal or z-axis of a central bore 12 . In a preferred superconducting embodiment, the primary magnet coils are supported by a former 14 and received in a toroidal helium vessel or can 16 . The vessel is filled with helium to maintain the primary magnet coils at superconducting temperatures. The can 16 is surrounded by a series of cold shields 18 which are supported in a vacuum dewar 20 . Of course, annular resistive magnets, open magnets, and the like are also contemplated. A whole body gradient coil assembly 30 includes x-, y-, and z-gradient coils mounted along the bore 12 for generating gradient magnetic fields, G x , G y , and G z along the x, y, and z axes, respectively. Preferably, the gradient coil assembly is a self-shielded gradient coil that includes primary x, y, and z-coil assemblies 32 plotted in a dielectric former and secondary x, y, and z-coil assemblies 34 that are supported on a bore defining cylinder of the vacuum dewar 20 . A whole body radio frequency coil 36 is mounted inside the gradient coil assembly 30 . A whole body radio frequency shield 38 , e.g., copper mesh, is mounted between the whole body RF coil 36 and the gradient coil assembly 30 . An insertable radio frequency head coil system 40 is removably inserted into the bore of an examination region defined about an isocenter of the magnet 10 . In the illustrated embodiment, the insertable radio frequency coil system 40 comprises front or face coil section 42 and rear or back coil section 44 . The front coil section 42 and the rear coil section 44 are shown aligned in opposing, facing relation defining a volume sized to receive a subject's head. The front coil is configured for maximum sensitivity to radio frequency signals along a first axis perpendicular to the main field or z-axis, e.g., the vertical axis. The rear coil is configured for maximum sensitivity to signals along an axis perpendicular to the first axis and the main field axis, e.g., the horizontal axis. In this manner, the front and rear coils are magnetically isolated and achieve quadrature detection. An operator interface and control station 50 includes a human-readable display 52 , such as a video, CRT, CCD, LCD, active matrix monitor, or the like, and one or more operator input devices including a keyboard 54 , a mouse 56 or other pointing device, such as a trackball, track pad, joystick, light pen, touch-screen overlay, and the like. A computer control and reconstruction module 58 includes hardware and software for enabling the operator to select among a plurality of preprogrammed magnetic resonance sequences that are stored in a sequence control memory of a sequence controller 60 . The sequence controller 60 controls gradient amplifiers 62 connected with the gradient coil assembly 30 for causing the generation of the G x , G y , and G z gradient magnetic fields at appropriate times during the selected gradient sequence. A digital transmitter 64 causes a selected one of the whole body and insertable radio frequency coils to generate B 1 radio frequency field pulses at times appropriate to the selected sequence. In certain embodiments, the coil construction 40 is employed as both a transmitter and receiver coil. The use of coil construction 40 for transmission and receiving is particularly advantageous for imaging methods which employ pre-excitation or presaturation pulses prior to the imaging portion of the pulse sequence, such as flow tagging angiographic methods, fat saturation methods, and the like. Resonance signals received by the coil construction 40 are demodulated by a data acquisition circuitry 66 and stored in a data memory 68 . A reconstruction or array processor 70 performs a two- or three-dimensional inverse Fourier transform, or other known transform, to reconstruct a volumetric image representation that is stored in an image memory 72 . A video processor 74 under operator control converts selected portions of the volumetric image representation into slice images, projection images, perspective views, or the like as is conventional in the art for display on the video monitor 52 . Referring now to FIG. 2, in a preferred embodiment of the data acquisition electronics 66 , the signal from each of n individual RF coils in the head coil system 40 is amplified by a corresponding one of n individual preamplifiers 80 a , 80 b , . . . , 80 n , where n is the number of receiver coils in head coil system 40 . The individual amplified signals are demodulated by n individual receivers 82 a , 82 b , . . . , 82 n and fed to an array of A/D converters including n individual A/D converters 84 a , 84 b , . . . , 84 n . A digital combiner 90 processes, weights, and combines the individual digital signals using standard digital signal processing techniques. The operator can also control the combiner 90 to divide the signals to be reconstructed to a plurality of related images. Alternatively, the signals from the coils can be digitized and then demodulated with digital receivers. The number of receiving channels depends on the particular MRI system and thus, it will be recognized that it is not necessary that the number of receiver channels be equal to the number of RF coils. For example, the signals from a plurality of coils may be multiplexed or otherwise combined in analog or digital fashion with appropriate combining circuitry as necessary in light of the number of receiver channels available on the imaging system employed. Referring now to FIG. 3, there appears a block diagram illustrating an alternative embodiment of data acquisition circuitry 66 . The 90° out of phase analog signals received by the front and rear RF coils of head coil system 40 are combined by a conventional quadrature coil combiner 80 , which typically phase shifts and adds the received signals. The resulting combined signal is supplied to a receiver 82 . Receiver 82 demodulates the combined signal and an analog-to-digital converter 84 digitizes the signal to numerical data representative of the magnetic resonance signals. The data thus produced is stored in the data memory 68 . Referring now to FIG. 4, there is shown a first exemplary embodiment of the head coil construction 40 according to the present invention. The front coil section 42 and the rear coil section 44 are constructed such that when arranged in facing relation, as depicted, they are inherently decoupled. As used herein, the terms “inherently decoupled” and “intrinsically isolated” describe coils or coil arrays that exhibit little or no mutual inductance. While complete decoupling is desirable, it will be recognized that complete decoupling is often a condition that cannot be met. Therefore, the terms “inherently decoupled” and “intrinsically isolated” are not intended to preclude small amounts of coupling that are acceptable to the operation of the coils. In the preferred embodiment, the decoupling is achieved by designing the front and rear coils to be linearly polarized along orthogonal axes, although other decoupling techniques are also contemplated. The inherent decoupling enables the front coil section 42 to be freely moved with respect to the rear coil section 44 , or to be removed altogether, without the need to retune either coil system. Also, the front coil section 42 is exchangeable with alternate coil systems having field sensitivity in the same direction, for example, having different sizes, coil configurations, and so forth, without the need to retune the rear coil system 44 . The front coil section 42 of head coil construction 40 comprises a housing 100 constructed of a nonconductive material enclosing conductive RF coils and one or more fasteners or fastening systems 104 . The fasteners 104 are depicted as elongate in the z-direction allowing front coil 42 to be removed and/or removably replaced at a plurality of, and preferably any number of, positions along the z-axis. The manner in which the front coil 42 can be freely positioned with respect to rear coil 44 is illustrated more clearly in FIG. 6 . Fasteners 104 are preferably hook and loop fasteners, such as Velcro® or similar material. Other fastener types include, but are not limited to, removably attachable adhesive material, one or more clamps or latches, straps, snap fit fasteners, fasteners forming a sliding engagement between the coil halves, such as a guide pin, guide roller, guide rib, and so forth engaging a complimentary groove. A means for reproducing a given set up can optionally be provided, such as a scale or other markings or indicia on the housings 100 and 102 . Where a sliding engagement between the coil halves is employed, they can optionally be positionable in a plurality of predetermined positions, for example, by providing one or more resilient or spring biased protrusions engaging a series of complimentary openings or depressions on the fastener 104 or housing halves 100 or 104 . In still further embodiments, handles can be provided on the detachable/relocatable coil section housings to facilitate coil section movement, removal, and replacement. The coils of the head coil construction 40 are illustrated in FIG. 5 . In the embodiment shown, the front coil section 42 comprises a pair of overlapping saddle or loop coils 106 and 108 , which are overlapped and positioned for minimum mutual inductance to form a phased array. Other coils which have maximum sensitivity in the vertical direction are also contemplated. The rear coil section 44 comprises a pair of overlapping butterfly coils 114 and 116 arranged in a phased array. Other coils with maximum sensitivity in the horizontal direction, such as double-D coils, are also contemplated. The coils are built with a conductive material, including but not limited to copper, aluminum, silver, or other conductive material. The coils can be built, for example, by laminating a nonconductive substrate with copper or other conductive foil, depositing a layer of copper or other metal onto a nonconductive substrate, and so forth. The coils can include conventional RF coil circuit components such as capacitors and so forth as appropriate to tune or match the coils as is known to those skilled in the art. Referring now to FIGS. 7 and 8, there is shown a head coil construction 40 ′ according to a second exemplary embodiment of the present invention. The head coil 40 ′ comprises a front coil section 42 ′ and a rear coil section 44 arranged in facing relation. Again, coil configurations which are inherently decoupled have been selected. The front coil section 42 ′ in this embodiment is freely moveable and removable with respect to rear coil section 44 without the need to retune either coil system. Also, the front coil section 42 ′ is exchangeable with alternate coil systems having field sensitivity in the same direction, for example, having different sizes, coil configurations, and so forth, without the need to retune the rear coil system 44 . A head coil system that comprises a plurality of differently configured front coil sections 42 and 42 ′, and the manner of their interchangeability, is illustrated in FIG. 10 . Referring again to FIGS. 7 and 8, front coil section 42 ′ of the head coil construction 40 ′ comprises a housing 100 ′ constructed of a nonconductive material enclosing a conductive RF coil 106 ′ and one or more fasteners 104 , as detailed above by way of reference to FIG. 4 . Again, fasteners 104 allow removal of the front coil 42 ′ and/or removable placement of front coil 42 ′ in a plurality of positions along the z-direction in a manner analogous to that shown in FIG. 6 . Likewise, coil system 42 ′ can also be rotated, e.g., 180 degrees, as illustrated in FIG. 9 . This facilitates placing the front coil close to the region of interest (ROI) to optimize sensitivity to signals from that region, but displaced from sources of artifacts such as moving eyes, metal dental work, and the like. Further, the fasteners can be used to attach other equipment in addition to or instead of the front coil section 42 ′. The coils of the head coil construction 40 ′, illustrated in the embodiment of FIG. 8, include a front coil section 42 ′ comprising a single loop saddle coil 106 ′ and the rear coil section 44 ′, comprising a pair of overlapping butterfly coils 114 and 116 arranged in a phased array. The coils are built with a conductive material and can include additional circuit components as described above by way of reference to FIG. 5 . The use of horizontal field coils in the rear coil is particularly advantageous when imaging the base of the brain, which is in close proximity to the rear coil. When other areas are of primary interest, the front coil can be the horizontal field coil and the rear coil can be the vertical field coil. In preferred embodiments, in addition to being physically displaceable, removable, and/or interchangeable, it is particularly advantageous that the front and rear coil systems of the present invention are electronically individually and selectively removable from the circuit. Likewise, it is particularly advantageous, when either or both of front and rear coil sections are multi-coil systems, that individual coils thereof be electronically individually and selectively removable or replaceable. In certain embodiments, the rear coil 44 includes a coil or a phased array of coils having a maximum sensitivity in a horizontal direction and a coil or phased array of coils having a maximum or predominant sensitivity in the vertical direction. An exemplary embodiment of such a rear coil arrangement is illustrated in FIG. 11, which includes overlapping butterfly coils 114 and 116 , and which further includes overlapping loop coils 120 and 122 . In operation, when a front coil (e.g., 42 , 42 ′)is present, the loop coils 120 and 122 are electronically removed from the circuit. However, when the front coil is removed in accordance with this teaching, coils 120 and 122 can be engaged and the rear coil alone can be used alone to provide quadrature detection. This configuration is advantageous for imaging the cervical spine and the back of the head, and for fMRI applications requiring access to the subject's face. The use of the rear coil section illustrated in FIG. 11 alone in a non-quadrature mode is also contemplated, e.g., wherein a front coil section is removed and wherein coils 120 and 122 are electronically removed. In operation, the RF coil construction in accordance with this teaching allows the MRI operator to perform anatomical imaging of the entire head followed by facile change in coil configuration, e.g., coil or coil set removal (either physical or electronic), adjustment of the front coil or coil set placement, exchange of coil sections for stimulation devices, comfort devices, or alternate coil sets. Calibration, landmark adjustment of the coil, and repeatable position of stimulation devices can also be improved through positioning. In certain embodiments, the entire coil system of the present invention is used for anatomical imaging of the entire head or the head and neck of the subject. The ability to slide or relocate the coil sections improve the adaptability in the coverage, accommodating a wide range of patient profiles, such as patient size, length of neck, kyphotic subjects, and other body types. The coil system in accordance with this teaching can also be used with any other coils or coils sets with which it is decoupled. For example, a head coil system in accordance with this teaching can be operated with a spinal imaging array for imaging the central nervous system. Other coils that can be used with the coil system of the present invention include thyroid coils, cardiac coils, or other local coils, such as a coil for imaging trauma sites, and so forth. Functional images may require only a portion of the region of interest to be acquired. Thus, during fMRI studies, one or more coils are moved or removed (either physically or electronically) to more closely tailor the imaging field of view (FOV) to match the region of interest during fMRI (e.g., the region appropriate to the brain response sought to be observed). This improves imaging throughput and accuracy while also improving access for placement of stimulation devices for use in fMRI experiments. In especially preferred embodiments, stimulation devices or patient comfort devices are connected, e.g., using fasteners 104 , or otherwise, or placed into positions vacated by the detached coil sections. Comfort devices are helpful in achieving patient cooperation, e.g., in the patient cooperating to remaining still. Comfort devices which may be employed with the present invention include, for example, audio and/or visual devices for the presentation of music, movies, television, and so forth. Advantageously, the comfort devices are exchangeable with removable coil section, for example, occupying a space vacated by the removal of a coil section. Coil sections integrating such comfort devices are also contemplated. In certain embodiments, a visual stimulation fMRI experiment is performed using the coil system in accordance with the present invention. The front coil section is moved to a position that does not obstruct the subject's field of vision (and optionally electronically removed) or physically removed. In a preferred aspect, the imaged region comprises the occipital lobe and cerebellum regions of the subject, and the imaged region does not include the subject's eye region. The coil construction of the present invention can also be modified to integrate stimulation devices, e.g., on or within the coil housing. For example, a combined stimulation device/RF coil section can include, for example, an auditory stimulation device such as audio speakers (e.g., in a headphone-like configuration within the coil section), optical displays, and the like. It will be recognized that the present invention is not limited to the above-described embodiments and that the invention is also applicable to other coil types. For example, the front coil loops are not limited to the configurations shown, and can comprise planar and non-planar loops (circular, square, rectangular, elliptical) and phased arrays thereof, Helmholtz coils, and the like. Likewise, the rear coil section can comprise a single butterfly coil or a phased array of more than two butterfly coils, ladder coils, double-D coils, and the like. For optimal signal-to-noise ratio, the front and rear coil systems have a quadrature relationship. Likewise, although the invention has been shown and described herein primarily by way of reference to a moveable, detachable, and/or interchangeable front coil section that is particularly suited for fMRI experiments requiring access to the facial region, other arrangements are contemplated as well. For example, the present invention can be readily adapted so as to provide access to the subject's ears, for example, through the use of removable coils or through the use of a coil configuration and housing having openings or cutaway regions allowing access to the ears. The description above should not be construed as limiting the scope of the invention, but as merely providing illustrations of some of the presently preferred embodiments of this invention. In light of the above description and examples, various other modifications and variations will now become apparent to those skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims. Accordingly, the scope of the invention should be determined solely by the appended claims and their legal equivalents.

An RF coil construction ( 40, 40′ ) includes removable, relocatable, and/or detachable sections ( 42, 44 ) that are inherently decoupled. The sections can be relocated, removed, or exchanged with sections having different coil sizes or coil configurations, allowing the coil configuration to be tailored to a desired imaging procedure and region of the brain. The coil construction provides space for stimulation devices and adjusting patient access and comfort. Since the operator can select coil removal or placement to reduce the amount of data outside the region of interest, the coil construction can also reduce scanning and reconstruction time, reduce artifacts, and provide increased temporal resolution and image throughput.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to provisional application No. 62/299,367, filed Feb. 24, 2016, the entire contents of which are hereby incorporated by reference. FIELD OF THE INVENTION [0002] The present invention relates to hooks for hanging tools. More precisely, the present invention is directed to improvements to a tool mounted multi-position carrying hook. BACKGROUND OF THE INVENTION [0003] Tool hooks are typically used to carry a portable tool or like implements around a job site to leave the user's hands free to do other things such as climb a ladder, support or align construction components, operate other tools, or perform other tasks. One type of hook is separate from the tool device and attached to a user's belt or other user location while the tool is placed and replaced on the hook. Another type of hook is attached as part of the tool—the hook and associated tool are placed and replaced together on the user's belt or other user location. An example of the first type is a hook that is normally affixed to a tool belt upon which a tool is selectively placed. A common example of the second type is a tape measure with integrated hook. SUMMARY OF THE INVENTION [0004] The present invention in a preferred embodiment includes a hook that is normally attached to a portable or hand held tool or other device that is to be carried by a user. The hook is movable on the tool between different positions whereby the hook is usable at or from selectable locations of the tool. The hook may also include a stowed position in which it is not normally accessible for use. For example, the hook may selectively extend from a left and right side of a tool, or only one side, to accommodate different handed users. The hook may further be stowed out of the way to extend from neither side. BRIEF DESCRIPTION OF THE DRAWINGS [0005] FIG. 1 is a left side elevational view of a tool incorporating a deployable belt hook, with the hook stowed. [0006] FIG. 1A a rear elevational view of the tool of FIG. 1 [0007] FIG. 2 is the tool of FIG. 1 with the hook deployed on a left side of the tool. [0008] FIG. 2A is a rear elevational view of the tool of FIG. 2 [0009] FIG. 3 is the tool of FIG. 1 with the hook, not visible, deployed on the right side of the tool. [0010] FIG. 3A is a rear elevational view of the tool of FIG. 3 . [0011] FIG. 4 is a left rear perspective detail view of the tool showing the hook in the stowed position. [0012] FIG. 5 is the tool of FIG. 4 with the hook in an intermediate position between deployed and stowed. [0013] FIG. 6 is the tool of FIG. 4 with the hook deployed on the left side of the tool. [0014] FIG. 7 is a right front perspective detail view of a rear of the tool of FIG. 4 with the hook deployed on the right side of the tool. [0015] FIG. 8 is a partial cross-sectional view of the tool of FIG. 4 showing hook support and securing elements. [0016] FIG. 9 is a left rear perspective view of a subassembly of a hook and support elements. [0017] FIG. 10 is a left front perspective view of the subassembly of FIG. 9 . [0018] FIG. 11 is a rear perspective view of a hook subassembly release button. [0019] FIG. 12 is a rear perspective view of a hook support structure. [0020] FIG. 13 is a rear perspective view of a belt hook. [0021] FIG. 14 is a front perspective view of the subassembly of FIG. 10 , viewed from a more front position. [0022] FIG. 14A is the cross-sectional view indicated in FIG. 14 in a pre-assembly condition. [0023] FIG. 14B is the view of FIG. 14A in an assembled condition. [0024] FIG. 15A is a cross-sectional view of the subassembly of FIG. 14 , with the belt hook not shown and with a release button extended. [0025] FIG. 15B is the view of FIG. 15A with the release button pressed. [0026] FIG. 16 is the view of FIG. 9 with a section line indicated. [0027] FIG. 17 is the perspective, partial cross-sectional view indicated in FIG. 16 . [0028] FIG. 18 is a left, front perspective view of a tool housing showing a subassembly mounting. [0029] FIG. 19 is a top left side perspective view of a tool with an alternative embodiment deployable belt hook, with the hook stowed. [0030] FIG. 20 is the tool of FIG. 19 with the hook deployed. [0031] FIG. 21 is a top view of the tool of FIG. 20 . [0032] FIG. 22 is a right side elevational view of the tool of FIG. 19 with a cut-away exposing hook elements. [0033] FIG. 22A is a transverse cross-sectional view at a hook mounting of the tool of FIG. 22 . [0034] FIG. 22B is a longitudinal cross-sectional view of the tool of FIG. 22 with the hook stowed. [0035] FIG. 22C is the view of FIG. 22B with the hook deployed. [0036] FIG. 23 is a perspective view of a belt hook component of FIGS. 19-22 . [0037] FIG. 24 is an alternative embodiment double hook. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0038] FIGS. 1 to 3 show a preferred first embodiment of a hook assembly fitted to a rear of a staple gun type device. As illustrated, the staple gun is a “forward action” type with a pressing area of handle 12 being above the front area of body 10 where the staples are ejected (i.e., left side of the three side elevation views). A length of the body extends from the front to a rear. A selectively deployable belt hook subassembly is preferably fitted near or at a rear of grip opening 17 within cavity or opening 15 of body 10 . Body 10 includes an upper grip area 13 above the grip opening and a lower body portion 14 under grip opening 17 . Handle 12 forms an upper region of a grip portion of the tool. Preferably as shown, the hook subassembly is positioned lower and rearward on body 10 to clear the grip area of upper grip 13 and handle 12 . In this manner, the hook features do not interfere with gripping, carrying and using the tool while also keeping the hook supported tool balanced in a convenient position for grasping and use. [0039] The hook subassembly includes rotatable hook support structure 20 , release button member 40 and elongated hook 30 . These elements are shown in most of the drawing figures. In FIG. 1 , hook 30 is stowed between sidewalls of body 10 , shown hidden in FIG. 1A . The hook subassembly preferably fits entirely, or nearly so, within confines of body 10 in the stowed condition. Therefore, the provision of the hook feature does not need to add any obstructions or bulk to the size of the tool with which it is used. In this position, the hook is fully out of the way to allow normal use of the staple gun or other tool. The movable hook structure is substantially confined within body 10 of the tool while body 10 , or the tool overall including the hook, need not be enlarged to fit this structure or related attachments thereof although it may be so enlarged. In particular the stowed hook is confined between two sides of the body as well as preferably between a top and a bottom of the body or related structure. In FIG. 1 hook 30 is vertically aligned with hook 20 , being below the support as illustrated. For example, a user who does not wish to use a belt hook will not suffer any compromise in the tool's function or bulk by its inclusion with the tool. As described here the bulk of the tool is an external overall size or envelope of the device wherein the stowed hook fits substantially entirely within the envelope of the tool. This contrasts with typical prior tool mounted hooks which necessarily protrude, or include mountings that add bulk, to an associated tool. Other implements to be carried, for example, hand and power tools and small household appliances, may be used in association with the present invention deployable hook. [0040] Hook support 20 includes a longitudinal axis by which it is pivotally mounted to body 10 . Button 40 includes round perimeter 43 , FIG. 9 . Hook support 20 includes boss 23 extending into housing recess 19 , FIG. 8 , hidden lines in FIG. 18 . Together sides 43 and boss 23 form a pivot axis about which the hook subassembly pivots. Alternatively, perimeter 43 may be part of hook support 20 , for example, with button coaxially fitted within a surrounding structure of hook support 20 . Further, body 10 may include bosses that fit to recesses of the hook subassembly to provide the pivot axis. Other suitable mountings are contemplated. [0041] In FIG. 2 , the hook extends or protrudes out of the page from a left side of the tool and to the left of hook support 20 , FIG. 2A . More broadly the hook is to a side of the hook support. This configuration will be convenient for a right-handed user, or where the work is to the right of a user. In this configuration when using the right hand the tool may be lifted in its usable position from a tool belt or equivalent item on the user. In this manner, the hand is placed atop handle 12 with the index finger extending through grip opening 17 at the front of the opening. In FIGS. 3 and 3A the hook extends from a right side of the tool as well suited for a left-handed user or a work object, implement, or tool that is to the left of a user where the left hand may be most convenient. The deployed hook extends substantially parallel to an exterior face of the body to form a “belt capture slot” whereby it normally captures a tool belt or similar item outside of and against the tool body. [0042] In the preferred embodiment shown, the hook subassembly rotates about 180° between usable positions or stops, in about 90° increments. The hook may rotate other than 180°, for example, a full circle or less, if desired. This may require opening cavity 15 to be larger, extending farther above hook support 20 , for example. As shown, opening cavity 15 extends downward whereby the hook stowed position has hook 30 located under hook support 20 . The hook subassembly may further be rotated by increments other than about 90°, for example about 45° or other positions to fit the contours of a particular tool to which it is attached. In various embodiments, the hook subassembly rotation may be loose or free, friction damped, include hard stops, reversibly locked in place, or any combination thereof, as described in more detail below. [0043] Button 40 is slidably fitted to hook support 20 ; see FIGS. 8, 15A and 15B . FIGS. 11 and 12 show these separate parts. Spring 50 or equivalent element biases button 40 out of recess 22 . Flanges 41 of button 40 terminate outwardly at shoulders 42 . Slot or slots 21 receive flanges 41 . Button 40 therefore can move axially in and out of recess 22 , between a disengaged and an engaged position respectively. Button 40 is substantially fixed in rotation within or upon hook support 20 , with an allowance for some looseness as a result of normal mechanical tolerance. In the normal outward position of FIGS. 8 and 15A , shoulders 42 engage notches or equivalent ribs 18 of housing 10 . In FIG. 8 , horizontal notches 18 are engaged by shoulders 42 . In the deployed left or right hook positions, FIGS. 2 and 3 , vertical notches 18 a, FIG. 18 , are engaged by shoulders 42 . Other relative relations between notches 18 , 18 a and shoulders 42 are contemplated. For example, slots 21 may be positioned about 90° or other angle to the vertical orientation shown in the view of FIG. 12 . With shoulders 42 engaged to notches 18 or 18 a, the hook subassembly is in a fixed or set position, held securely from rotating within cavity 15 or other equivalent location. If spring 50 is stiff enough then the stops may be less determinate or at the limit there are no stops or notches 18 at all whereby hook support 20 rotates against a simple friction engagement for example pressing shoulders 42 against a relatively smooth surface of body 10 . Alternatively, spring 50 may be softer or, along with button 40 , not present at all whereby hook support 20 rotates freely. [0044] Button 40 is exposed and accessible for use on a rear of the tool body as shown. To change the position of the hook, button 40 is pressed inward against the bias of spring 50 to the retracted button position shown in FIGS. 5 and 15B . Button 40 and the hook support structure are then in a released position. Recess 13 surrounding button 40 allows for full pressing of the button while holding the button generally flush with a surrounding housing surface or body envelope in the normal extended position of the button. In this way, the button will not protrude from the tool and can not be easily be pressed accidentally. [0045] With the button pressed, shoulders 42 are now flush with a rear 26 of hook support 20 , FIG. 15B . As seen in FIG. 8 , dashed lines, button 40 moves to the position 40 a while shoulder 42 moves to 42 a. This condition retracts the shoulders from notches 18 , see also FIG. 18 . In FIG. 5 , the hook subassembly is in an intermediate position between the three preferred positions of stowed and deployed. When the hook is moved to one of these preferably three determinate positions, button 40 automatically pops out into notches 18 or 18 a under the bias of spring 50 to hold and operationally fix the selected position of the hook support to the body. No further user action is required to fix the selected position. More or fewer determinate positions or stops may be provided by having more or fewer notches or other equivalent structures. [0046] Preferably, there are redundant features to hold rotational positions of the respective parts. For example, the exemplary embodiment has two slots 21 in hook support 20 with corresponding two flanges 41 of the button structure. Further, there are a pair of respective body notches 18 and 18 a to engage the pair of button shoulders 42 . With more than one rotational fixing feature, the hook is securely held in a selected position. More or fewer than two of each feature or equivalent may be used. The hook is rotationally fixed within movable limits determined by part tolerance and function. [0047] Hook support 20 may be a molded part with hollow front interior 24 ( FIG. 10 ) and a back for the rear features ( FIG. 12 ). This helps keep the structure light weight to minimize its effect on use of the associated tool. Along with recess 22 for button 40 , there is an optional ramp 27 . As seen in FIGS. 14A and 14B , ramp 27 allows for a snap fit of hook 30 into hook support 20 . Hook 30 is a preferably wire-formed structure while it may also be formed from sheet metal, plastic, fiberglass, or other material. The hook includes U returns 34 and internal legs 35 . Preferably single leg 37 , FIGS. 10 and 13 for example, is the operative element to form the tool belt capture slot. Bent ends 31 hold the hook within hook support 20 as seen in FIGS. 14 and 14B . See also FIG. 9 for the positions of these hook elements within hook support 20 . To assemble the hook to the hook support, legs 35 are pressed inward along ramps 27 , FIG. 14A . The legs deflect inward, 31 a and 35 a, until bent ends 31 have slid to catches 27 a, FIG. 14B . The legs then snap into position where bent ends 31 are locked behind catches 27 . Elongated recess 28 holds and stabilizes legs 35 against normal forces of use that would move the legs laterally within hook support 20 while catches 27 hold the hook from pulling rearward out of the hook support. The preferred embodiment snap fitted design is compact, low weight, and low cost. Angled end 33 of the hook guides the hook to behind a belt, waist band or other item of attire. [0048] As shown, the hook has a single operative leg 37 with the single leg extending along an outside of hook support 20 . The hook leg is able to move within and beyond an envelope of the body. As described herein, the envelope of the body is the shape, size or bulk of the body absent any protruding structure of a belt hook. The preferably single leg may include the two joined wire elements illustrated or the sheet metal structure described above. [0049] As shown, opening cavity 15 is fully surrounded within body 10 . In alternative embodiments, the hook subassembly may be fitted into a recess of the body, for example, open at a rear of the tool (not shown). Further, the hook may be mounted substantially externally to the tool, for example, upon ribs extending from the body (not shown) so that the hook subassembly is more exposed on the body. [0050] FIGS. 19 to 22 show a tool using an alternative embodiment deployable tool belt hook. Handle 112 is pivoted near a front of body 110 , left side in FIG. 19 . Grip opening 117 extends from a central area toward a rear of the body. In the illustrated staple gun type fastening device the main operational components, not shown, are in front of grip opening 117 . The hook structure shown may be applicable when there is more limited space available for the hook feature compared for example to the structure of the tool of FIGS. 1 to 18 . Hook 130 is preferably a wire form or equivalent structure. [0051] As seen hook 130 fits within narrow cavity or slot 115 without obstructing grip opening 117 . Slot 115 is about a same height as a diameter of the wire of hook 130 , being less than two times such a diameter. Fastener track 180 is immediately below slot 115 so that slot 115 fits in a small space between track 180 and grip opening 117 . Similar to cavity 15 of FIGS. 1 to 18 , the slot forming cavity 115 is located adjacent to and at a rear of the grip opening. In FIGS. 19 and 22B the hook is stowed. The hook including rear loop 132 is within confines of body 110 whereby the stowed hook does not add to a bulk of the tool. In the other assembly drawing figures, the hook is deployed in an operative position and available for use. The hook is widest at loop 132 and narrowest at clip area 131 . Loop 132 , inner leg 136 and outer leg 137 are all substantially co-planar whereby the wire form of hook 130 fits into narrow cavity slot 115 . In this manner, the plane of the hook defined by the loop and legs is substantially perpendicular to a horizontal plane of the tool as defined by the page of FIGS. 22B and 22C . When deployed leg 137 forms a belt capture slot between body 110 and leg 137 , FIG. 22C . [0052] In FIG. 22 hook pivot 135 is seen. The hook pivots about hinge area 113 of body 110 with a hook pivot axis described by pivot 135 being vertical, see also FIG. 22A . As shown, hinge area 113 includes a member from both halves of the housing body 110 which meet at pivot 135 to rotatably confine the hook. In the stowed position, inner leg 136 abuts rib 111 , or other limit stop structure, FIG. 22B . Inner leg 136 is between loop 132 and pivot 135 . [0053] Access opening 118 , FIGS. 19 and 20 , provides finger access to pull on loop 132 to allow outward deployment of the hook. Resilient detent bumper 120 includes exemplary ridge 121 to hold the hook stable in either the deployed or stowed position. Optionally, the bumper or equivalent structure may be relatively rigid while deflection of the hook wire provides the detent action. With the hook deployed and stable the tool can be clipped or held on a tool belt or equivalent item a user is wearing. The hook remains available for use in this configuration. If the hook is no longer needed it can be easily moved out of the way to the stowed position. [0054] Optionally, the hook of FIGS. 19 to 22 may be held in a position by a secondary structure such as a thumb screw, lever or similar, not shown. In particular, in the deployed position the hook then cannot be unintentionally pushed back in from its operative position. [0055] As shown hook 130 deploys from a single side of the tool. Optionally, the hook could extend both directions for example by rotating about its long axis, not shown, and pivoting out the right housing side. Further there may be two hooks stacked, not shown, that fit in a partially wider slot 115 and operate in opposed directions. Hook 130 may include a structure with two vertically spaced parallel hooks, FIG. 24 . Such a double hook pivots about the same pivot 135 . This taller structure may be suited when there is enough free space in the tool body to fit. Slot cavity 115 then has two spaced parallel slots or a wider single slot. [0056] While the particular forms of the invention have been illustrated and described, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention. It is contemplated that elements from one embodiment may be combined or substituted with elements from another embodiment.

An improved tool belt hook is selectively deployable on a portable tool or device. The hook structure is deployable in selected directions or positions on the tool. A stowed position is also preferably included wherein the hook structure is substantially contained within confines of the tool body to be out of a user's way. A closely integrated pushbutton release may allow the hook to rotate between selected operative positions and automatically engage to such position. The button is easily operated while effectively remaining within confines of the tool body. The tool hook assembly is compact and low cost.

TECHNICAL FIELD [0001] This invention relates to fastener products such as those having an array of projections arranged to resist shear displacement across the surface of the fastener product. BACKGROUNDS [0002] Some fasteners, for example, hook and loop fasteners, include fastener components with engageable elements constructed to engage elements of corresponding fastener components. In the case of self-engaging fasteners, the fastener elements of the two fastener components are similar or the same, and the two fastener components may be regions of a single sheet. [0003] There is a need in certain applications for fasteners that, when engaged, provide high shear strength properties in a desired direction. Some applications also require low cost fasteners offering good resistance to disengagement and in-place adjustability. [0004] There is also a need to be able to consistently and efficiently produce fastener components having differing functional characteristics, using techniques that require limited changeover in basic tooling, yet allow for adjustments to produce the desired fastener characteristics. SUMMARY [0005] According to one aspect of the invention, a self-engageable fastener component includes a sheet-form base, and an array of wedge-shaped, engageable elements extending integrally from at least one side of the sheet-form base. The engageable elements each have an engageable side, and a non-engageable side conterminous at an upper edge of the element. The upper edge of each engageable element defines a curve in top view, and the engageable sides of a majority of the elements are oriented in a common direction. [0006] In some embodiments, the engageable elements are arranged in at least one row along the sheet-form base, the row extending toward the single edge. For some applications, the elements are arranged in an array of multiple rows and columns. In preferred embodiments, the elements are arranged in multiple rows, with elements of adjacent rows offset from one another along their respective rows. The elements of adjacent rows are offset, for example, by about one-half a nominal spacing between adjacent elements within a row. [0007] In some implementations, the curve defined by the upper edge in top view is substantially circular with a constant radius of curvature. In preferred implementations, the constant radius of curvature is from about 0.25 to 2.5 centimeters. [0008] For some applications, the curve defined by the upper edge in top view is not circular, but is, for example, parabolic, ellipsoidal, hyperbolic, or a mixture of such curves. [0009] In preferred embodiments, a maximum elevation of the upper edge above the top surface of the sheet-form base is between about 0.025 and 6.3 millimeters, each engageable element has a width, measured along the sheet-form base perpendicular to said single edge, of between about 0.13 and 6.3 millimeters, each engageable element has a length, measured along the sheet-form base parallel to the edge, of between about 0.13 and 2.54 centimeters, and the non-engageable side of each fastener element rises from the sheet-form base at an angle of between about 5 and 45 degrees. [0010] In some instances, the engageable sides of the wedge-shaped elements overhang the sheet-form base, and the engageable side of each fastener element extends downward from the upper edge toward the sheet-form base at an undercut angle, measured in a midplane bisecting the fastener element and perpendicular to the sheet-form base, of between about 10 and 45 degrees. [0011] For some applications, the engageable elements extend outwardly from two opposite sides of the sheet-form base. In some instances, there are hook-shaped projections, and/or engageable loops proximate the wedge-shaped elements. [0012] In some implementations, the sheet-form base forms a tube, with the wedge-shaped elements extending from a curved surface of the tube. The curved surface can include an outer, or an inner surface of the tube. For some applications, the tube defines a longitudinal gap extending along its length between opposite edges of the sheet-form base. In some cases, the sheet-form base forms an elongated, U-shaped structure, and the wedge-shaped elements extend from an inside surface of the U-shaped structure, a majority of the engageable sides of the wedge-shaped elements directed away from an open edge of the U-shaped structure. In certain application, the wedge-shaped elements extend from an outside surface of the U-shaped structure. [0013] In some embodiments, the sheet-form base forms an elongated strap. In certain instances, the elongated strap includes only a single row of said wedge-shaped elements, all arranged with their engageable sides directed toward an end of the strap. For some applications, an aperture is defined adjacent one end of the strap, and the aperture sized to receive an opposite end of the strap therethrough. In preferred embodiments, the elongated strap includes an exposed retention edge along one side of the aperture, the retention edge is positioned to engage the engageable sides of the wedge-shaped elements with the opposite end of the strap pulled through the aperture, to resist removal of the strap from the aperture. [0014] For some applications, it is advantageous when the sheet-form base is secured to, and overlays a layer of resilient material, and the sheet-form base is flexible. [0015] In preferred embodiments, two fastener components, each as described above, are arranged with the engageable sides of their wedge-shaped elements overlapping one another to resist shear motion between the fastener components. [0016] According to another aspect of the invention, a method of making a fastener component includes providing a molding tool defining an array of cavities extending inwardly from an outer surface thereof. The moldable resin is transferred onto the outer surface of the molding tool, and the resin is pressed into the cavities of the molding tool, thus forming the engageable elements, while forming a base of resin on the surface of the molding tool, the base interconnecting the engageable elements. The cavities form engageable elements that are wedge-shaped, each wedge-shaped element including an engageable side, and a non-engageable side conterminous at an upper edge of the element. The upper edge of each engageable element defines a curve in top view, and the engageable sides of a majority of the elements are oriented toward a single edge of the sheet-form base. [0017] For some applications, the molding tool includes, for example, a rotatable mold roll positioned adjacent a counter-rotating pressure roll to define a pressure nip in which the moldable resin is pressed into the cavities to form the engageable elements. In some implementations, a sheet material is introduced into the nip with the moldable resin, and laminating the moldable resin to the sheet material under pressure in the nip. The sheet material can include, for example, a scrim material. [0018] In certain embodiments, the planar sheet material is formed into a tube, the engageable sides of a majority of the engageable elements being directed away from a common, open end of the tube. [0019] For some applications, the fastener component is in strap form, the method includes forming an aperture at one end of the fastener component, the aperture being sized to receive an opposite end of the fastener component. The fastener component includes an exposed retention edge along one side of the aperture, the retention edge being positioned to engage the engageable sides of the wedge-shaped elements with the opposite end of the strap pulled through the aperture, resisting removal of the strap from the aperture. [0020] According to another aspect of the invention, a seat bun includes a compliant material with a surface having a central region bounded on two opposite sides by elongated trenches, and a fastener component that includes a sheet-form base, and an array of wedge-shaped, engageable elements extending integrally from at least one side of the sheet-form base disposed within each trench. The engageable elements each have an engageable side, and a non-engageable side conterminous at an upper edge of the element. The upper edge of each engageable element defines a curve in top view, and the engageable sides of a majority of the elements are oriented in a common direction. The elements are arranged with the non-engageable sides of its wedge-shaped elements directed out of the trench. For some applications, the fastener components include elongated, U-shaped structures extending along each trench. In some instances, the fastener components comprise tubular structures embedded within each trench. [0021] The term “curve” as used herein is intended to include generally curved outlines that may encompass minor discontinuities or straight segments. [0022] The fastener components and fasteners disclosed herein can be particularly useful in applications requiring high shear strength. In addition to providing high shear strength, many of the fastener components and systems disclosed herein provide for ready disengagement and in-place fastener adjustability. Many embodiments can be molded in flexible form, with very low profile wedges, such that engaged sets of the fasteners occupy very little width between mating surfaces. The wedges can be arranged to allow engaged surfaces to be readily shifted for adjustment along rows of wedges, such as for adjusting the position of a picture frame fastened to a wall surface with such fasteners, for example, with the curved edges of the wedges of each row defining a series of detents for maintaining final engagement once shear load is reestablished between the wedges. The curvature of the edges helps to assist with adjustment of two mating arrays of wedges by allowing the apexes of the wedges to slide across one another without completely separating the mating fastener components, with the wedges overlapping. [0023] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features and advantages of the invention will be apparent from the description and drawings and from the claims. DESCRIPTION OF DRAWINGS [0024] FIG. 1 is a perspective view of a fastener component according to one embodiment. [0025] FIG. 1A is an enlarged top view of a portion of the fastener component shown in FIG. 1 . [0026] FIG. 1B is an enlarged side view of a portion of the fastener component shown in FIG. 1 . [0027] FIG. 1C is a perspective view of a fastener component according to an alternative embodiment. [0028] FIG. 1D is a top view of the fastener component of FIG. 1C . [0029] FIG. 2 is a top view of the fastener component shown in FIG. 1 . [0030] FIG. 2A is a cross-sectional view of the fastener component shown in FIG. 2 , taken along line 2 A- 2 A in FIG. 2 . [0031] FIG. 2B is an enlarged view of a portion of the fastener component shown in FIG. 2A . [0032] FIG. 3 is a top view of the fastener component shown in FIG. 2 , the fastener component oriented such that it is engaging a like fastener component, creating a fastener according to one embodiment. [0033] FIG. 3A is a cross-sectional view of the fastener shown in FIG. 3 , taken along 3 A- 3 A. [0034] FIGS. 3B-3C are top views of a portion of the fastener system illustrated in FIG. 3 . [0035] FIG. 4 is a diagrammatic view of a process for making the fastener component shown in FIG. 1 . [0036] FIG. 4A is a diagrammatic view of a process for making a fastener component shown in FIG. 4B or 4 C. [0037] FIG. 4B is a laminated fastener component made by the process shown in FIG. 4A . [0038] FIG. 4C is a fastener component made by the process shown in FIG. 4A using a scrim web material. [0039] FIG. 4D is a diagrammatic view of a process for making a fastener component with engageable elements on both sides of a sheet-form base. [0040] FIG. 5 is a diagrammatic view of an alternative process for making the fastener component shown in FIG. 1 . [0041] FIG. 6 is a diagrammatic top view of a portion of flat tooling. [0042] FIG. 7 is a cross-sectional view of a tool roll being cut. [0043] FIG. 7A is a side view of a dovetail cutter. [0044] FIG. 7B is an end view of a dovetail cutter. [0045] FIGS. 8-9 are perspective views illustrating formation of a tubular fastener component with engaging elements on the inside. [0046] FIG. 9A is a cross-sectional view of the fastener component shown in FIG. 9 (after joining), taken along line 9 A- 9 A in FIG. 9 . [0047] FIGS. 10-11 are perspective views illustrating formation of a tubular fastener component with engaging elements on the outside. [0048] FIG. 11A is a cross-sectional view of the fastener component shown in FIG. 11 , taken along line 11 A- 11 A in FIG. 11 . [0049] FIG. 12 is a perspective view of a tubular fastener system employing the tubular fastener components shown in FIGS. 9 and 11 . [0050] FIG. 13 is a perspective view of the tubular fastener component shown in FIG. 9A in a plastic body. [0051] FIG. 13A is a side view of a fastener component according to an embodiment. [0052] FIG. 13B is a side view of a fastener component according to another embodiment. [0053] FIG. 13C is a cross-sectional view of a fastener system employing the fastener components of FIGS. 13A and 13B . [0054] FIG. 14 is a perspective view of a mold insert illustrating the tubular fastener component of FIG. 9 (after joining) on a protrusion. [0055] FIG. 14A is a cross-sectional view of a tubular fastener component on a mold protrusion, a portion of the mold protrusion having a diameter larger than the nominal diameter of the fastener component, and the tubular fastener component including a region without engageable elements. [0056] FIG. 14B is a cross-sectional view of a tubular fastener component on a mold protrusion, the fastener component including a seal about an inner surface of the tubular structure. [0057] FIG. 14C is a cross-sectional view of a portion of a tubular fastener component showing overlapped edges that are tapered in thickness. [0058] FIGS. 15-16 are perspective views of alternative fastener components employing the fastener component shown in FIG. 1 . [0059] FIG. 17 is a side view of a fastener component according to an embodiment. [0060] FIG. 18 is a side view of a fastener system according to an embodiment. [0061] FIG. 19 is a perspective view of a fastening system according to an embodiment. [0062] FIG. 20 is a perspective view of a fastener component according to an embodiment. [0063] FIG. 20A is a perspective view of a fastening system according to an embodiment formed from the component of FIG. 20 . [0064] FIG. 21 is an alternative fastening system. [0065] FIG. 22 is a fastener product. [0066] FIG. 23 is a partial cross-sectional view of a fastener product having a releasably retaining arm in a fastened position. [0067] FIG. 24 is a perspective view of a molding nip for producing the fastener product of FIG. 26 . [0068] FIG. 25 shows area 25 of FIG. 24 . [0069] FIG. 26 is a perspective view of a fastener product sheet, and a product that has been separated from the sheet. [0070] FIG. 27 is a plan view of the fastener product of FIG. 26 . [0071] FIG. 28 is a cross-sectional view of a compliant material sandwiched between a tubular structure, and a base that includes engageable elements. DETAILED DESCRIPTION [0072] Referring to FIG. 1 , flexible fastener component 10 includes an array of arcuate engageable elements 12 integrally molded with and extending outwardly from one side of a solid sheet-form base 14 . The engageable elements 12 are arranged in scalloped rows R, and are preferably staggered, as shown. The engageable elements 12 each include an engageable side 18 and a non-engageable side 20 disposed opposite the engageable side. Preferably, the elements are substantially identical to each other, as shown. [0073] The engageable elements 12 may be formed by a process having a machine direction (MD) and a cross-machine direction (CD), in which case the engageable elements 12 may be arranged with rows R extending in the machine direction so that engageable sides 18 face uni-directionally in the cross-machine direction. Each engageable side 18 is defined by an upper edge 17 and by a lower edge 19 where the engageable element intersects the sheet-form base 14 . Both upper and lower edges 17 , 19 define curves, for example, a circular curve as shown in FIG. 1 , in the direction of the rows, for example, the machine direction. A circular curve is a curve that would sweep out a circle if it continued. Because the elements 12 are staggered, the apexes A 1 , A 2 of the arcuate engageable elements 12 in adjacent rows are offset from each other. [0074] In some embodiments, fastener component 10 is made of thermoplastic material. Suitable thermoplastic materials include polyethylenes, polypropylenes, polyamides, PVC, and polyesters. In other embodiments, especially when high chemical resistance and/or high temperature stability is required, fastener component 10 is made of a thermoset material. Suitable thermoset materials include natural rubbers, synthetic rubbers and rigid or flexible polyurethanes. [0075] In some embodiments, the upper and/or lower edge(s) 17 , 19 may define a circular curve with a constant radius of curvature. To illustrate this point, the radius of curvature of lower edge 19 shown in FIG. 1 is r 19 , while the radius of curvature of upper edge 17 is r 17 . The radius of curvature may be, for example, from about 0.1 inch to about 1 inch (0.25 cm-2.5 cm). In other embodiments, the upper and lower edges 17 , 19 may define a curve that is non-circular and, therefore, has a changing radius of curvature. Examples may include curves that are parabolic ellipsoidal or hyperbolic in shape. FIGS. 1C-1D illustrate a fastener component 11 with parabolic upper and lower edges 17 ′, 19 ′. [0076] In some embodiments, the maximum height H ( FIG. 1 ) of the engageable elements 12 above the sheet-form base 14 at the apexes A 1 , A 2 is, for example, from about 0.001 inch to about 0.250 inch (0.0025 cm-0.64 cm). In other embodiments, where the engageable elements resemble “fish scales,” the height H is, for example, from about 0.001 inch to about 0.050 inch (0.0025 cm-0.13 cm). “Fish scale” engageable elements are useful, for example, when maximum flexibility is desired or when the application requires a low degree of skin irritability, for example, when the fastener component is fixed to a garment of clothing. [0077] In some embodiments, a maximum length L of the engageable elements 12 in the direction of the rows is, for example, from about 0.05 inch to about 1.0 inch (0.13 cm-2.5 cm), while the maximum width W in the engaging direction along the sheet-form base is, for example, from about 0.005 inch to about 0.25 inch (0.013 cm-0.64 cm). In some embodiments, the spacing S between rows in the engaging direction, measured along the sheet-form base from an end of a row to the beginning of an adjacent row is, for example, from about 0.005 inch to about 0.25 inch (0.13 cm-0.64 cm). [0078] Referring to FIGS. 2-2B , each engageable element 12 defines angles α and β with respect to sheet-form base 14 . Referring now particularly to FIG. 2A , angle α is the angle formed between the top surface of the sheet-form base and the top surface of the engageable element. Referring to FIGS. 2 and 2 B, lower edge 19 is not directly below upper edge 17 , but is offset, the offset defining an undercut angle β. Referring particularly to FIG. 2B , angle β is the angle formed between a line L 1 connecting upper edge 17 to lower edge 19 in a plane P E in the engaging direction ( FIG. 1 ) that is perpendicular to the sheet-form base, and a line L 2 in the same plane that connects upper edge 17 to the sheet-form base. In some embodiments, angle α is, for example, from about 5° to about 45°, while angle β is, for example, from about 10° to about 45°. The presently preferred embodiment has an α angle to 30° and a β equal to 15°. [0079] Fastener components having engageable elements like those shown in FIG. 1 are useful for engaging, for example, similar fastener components, forming a high shear strength fastener system. Applications and methods of forming the components will be discussed further below. [0080] Referring to FIGS. 3-3C , a high shear fastener 30 includes two flexible fastener components 10 , oriented such that the engageable elements 12 of the top fastener component 32 face the engageable elements 12 of the corresponding bottom fastener component 34 . The top fastener component 32 is further oriented so that the engageable sides 18 of elements 12 point from left to right. Bottom fastener component 34 is oriented such that engageable elements 12 extend upwardly to mate with the engageable elements 12 of the top fastener component 32 . The bottom fastener component 34 is further oriented so that the engageable side 18 of elements 12 point from right to left. Now, referring particularly to FIG. 3A , when the bottom fastener component 34 is fixed, and the top fastener component 32 is moved in a direction indicated by arrow 36 , a high shear engagement occurs as the engageable sides 18 of the fastener elements 12 of both components restrict movement in this direction. However, when the top fastener component 32 is moved in the opposite direction, indicated by arrow 38 , no engagement of the top fastener component 32 with the bottom fastener component 34 occurs and the two components slide relatively freely past each other, making a “clicking” sound as the engageable elements slide past each other. Referring back to FIG. 3 , top fastener component 32 and bottom fastener component 34 are also relatively free to slide past one another in the direction in which the rows of elements extent, i.e., the directions indicated by arrows 40 and 42 . Referring particularly to FIGS. 3B and 3C , which are top views of row R 1 engaged with row R 2 ( FIG. 3 ), when row R 1 is fixed and row R 2 is moved in a direction indicated by arrow 40 or 42 , there is slight resistance to movement, as engaging elements “rise up” from wells 44 ( FIG. 3B ) through the maximum of engageable side 18 and come to rest in adjacent wells 44 ( FIG. 3C ). This feature allows for in-place fastener adjustability. As an example to further illustrate adjustability, fastener component 10 may be, for example, attached to a wall in a room with the engageable side directed upwardly toward the ceiling of the room. Another fastener component 10 may be, for example, attached to the back of a shallow, heavy rectangular object, such as a picture frame with the engageable side directed downwardly. The heavy object may now be placed on the wall and held in place by the engageable elements. While still in-place on the wall, the heavy object may be translated laterally in units of length L along the wall, rising up against gravity from wells 44 and passing over each arcuate element before coming to rest in the adjacent wells as described above. Referring now to FIGS. 1 and 3 A, decreasing spacing S allows for finer adjustment steps. In the example above when the heavy object is a picture frame, decreasing spacing S allows for greater adjustability (smaller steps) along the height of a wall. Referring now again to FIGS. 2A-2B and FIG. 3 , increasing angle α makes it more difficult to slide components 32 and 34 past each other when oriented in the high shear mode discussed above. Increasing angle β allows for enhanced robustness in peel mode. While an angle β equal to 0° will work in shear mode, it will not provide much resistance in peel mode. In the example above where the heavy object is a picture frame, the robustness translates into how easy it is to accidentally cause the picture frame to fall off the wall by bumping the frame in a direction perpendicular to the wall to which it is attached. [0081] Referring now to FIG. 4 , a process for forming the fastener component 10 shown in FIG. 1 is illustrated. Thermoplastic resin 50 from extruder 52 is introduced into nip 54 formed between a supporting pressure roll 56 and a mold roll 58 . Pressure in the nip causes thermoplastic resin 50 to enter blind-ended forming cavities 60 of mold roll 58 while excess resin remains about the periphery of the mold roll and is calendared to form sheet-form base 14 . As the rolls 56 , 58 rotate in opposite directions (shown by arrows), the thermoplastic resin proceeds along the periphery of the mold roll until it is stripped by stripper roll 62 . The resulting fastener component 10 is described above. The direction of travel of the material illustrated in FIG. 4 is referred to as the “machine direction” (MD) of the material and defines the longitudinal direction of the resulting product 10 , while the cross-machine direction (CD) is perpendicular to the machine direction. Further details regarding processing are described in Fischer, U.S. Pat. No. 4,775,310, the disclosure of which is hereby incorporated in full by reference. [0082] In another embodiment, illustrated in FIG. 5 , an alternate technique for producing fastener component 10 of FIG. 1 is employed. The process is similar to that described above with reference to FIG. 4 , except only a mold roll 58 is used, i.e., no pressure roll 56 is necessary. Here, the extruder 52 is shaped to conform to the periphery of the mold roll and the extruded resin 50 is introduced directly to a gap 64 formed between the mold roll and the extruder 52 . From here, flexible fastener component 10 is stripped from the mold cavities 60 by stripper roll 62 as described above. Further details regarding this process are described by Akeno in U.S. Pat. Nos. 5,781,969 and 5,913,482, the disclosures of which are hereby incorporated in full by reference. [0083] Referring now to FIGS. 4A-4C , a process for forming fastener components bonded to a web material is illustrated. Web material 53 is brought into nip 54 formed between roll 58 and roll 56 as discussed above. Web material can be, for example, a relatively non-porous material such as a plastic sheet material or a relatively porous textile gauze material such as a scrim material. If the web material is relatively non-porous, fastener components like that of FIG. 4B result. If the web material is a relatively porous material, fastener components like that of FIG. 4C result, as the molten resin penetrates the pores of the scrim material. Depositing molten resin upon a scrim material is discussed in U.S. patent application Ser. No. 10/688,301, filed Oct. 15, 2003, the entire content of which is hereby incorporated by reference. [0084] Other processes for forming flexible fastener component 10 are possible. For example, the processes described by Jens, U.S. Pat. No. 6,432,339, the disclosure of which is hereby incorporated in full by reference. In yet another process, flexible fastener component 10 may be formed from sheets of a pre-form material that may be, for example, pre-heated and compression molded, the heat and the pressure forming the engageable elements 12 . The advantage of this type of processing may be, for example, the use of flat, inexpensive tooling and the use of a relatively inexpensive hydraulic press. Another advantage of the compression molding process is that it allows for the use of thermoset resins that offer, for example, higher temperature stability and better chemical resistance when compared to thermoplastic materials. The disadvantage of this type of processing may be, for example, relatively low throughput since it is a batch process instead of a continuous process. [0085] Referring to FIG. 4D , a process for forming fastener components with engageable elements on both sides of a sheet-form base is illustrated. Thermoplastic resin 50 from extruder 52 is introduced into nip 54 formed between two mold rolls 58 . Pressure in the nip causes thermoplastic resin 50 to enter blind-ended forming cavities 60 of mold rolls 58 , forming a double-sided fastener component. [0086] Referring now specifically to Box 4 , Box 4 A, Box 4 D and Box 5 of FIGS. 4, 4A , 4 D and 5 , respectively, additional post processing may be applied to fastener components. For example, Boxes 4 , 4 A, 4 D and 5 may represent “flat-topping” stations as described by Provost in U.S. Pat. No. 5,953,797, the disclosure of which is hereby incorporated in full by reference. Flat-topping can, for example, increase the peel strength of fastener systems by increasing the overhang of the engageable elements. [0087] Referring now to FIG. 6 , flat tooling can be machined to create, for example, a compression mold tool. The advantages of compression molding fastener components have been described above. Cavities 60 can be machined or burned (e.g., by EDM) into the tool. Other methods for forming cavities are known in the art. [0088] Referring to FIG. 7 , entire mold rolls 58 or large portions 76 thereof can be machined by holding mold roll 58 on table 70 and machining its surface, for example, with a CNC milling machine 72 to form cavities 60 . The milling machine may include, for example, a dovetail cutter 74 . In comparison to forming mold rolls from machined plates, this process has the advantage, for example, of fewer parts to assemble. In addition, this process can allow for, for example, less expensive tooling, faster tooling changeover, easier tool cleaning and may eliminate or reduce flashing. [0089] FIGS. 7A-7B show, a dovetail cutter 74 suitable for making the tooling described above. The geometry of cutter 74 can be described in terms of cutter diameter A, face width B, shank diameter C, overall length D and included angle φ. Suitable cutters may have, for example, the following dimensions: DIMENSION RANGE A 0.125 inch-3.000 inch (0.318 cm-7.62 cm) B 0.125 inch-2.000 inch (0.318 cm-5.08 cm) C 0.125 inch-1.500 inch (0.318 cm-3.81 cm) D 1.500 inch-4.000 inch (3.81 cm-10.16 cm) φ 30-60° [0090] Referring to FIGS. 8-9A , a tubular fastener component is made wrapping proximal end 80 and distal end 82 of fastener component 10 toward each other, as indicated by arrows 81 and 83 , until ends 80 and 82 physically touch or only a small gap 88 remains. Joining touching ends 80 and 82 can be accomplished by using, for example, an impulse sealer or an ultrasonic welder. In other embodiments, ends 80 and 82 may be joined by filling gap 88 with an elastomeric adhesive. This method can be particularly advantageous when a flexible joint is desired. A flexible joint may be desired, for example, when the tubular structure is placed on an oversized member (not shown), for example, an insert in a reactive injection mold or injection mold. Tubular fastener component 90 includes a first open end 84 and a second open end 86 . In another embodiment, the shape of the tubular fastener is fixed in the shape shown in FIG. 9 (i.e., gap is not closed) by heating the sheet-form base on the side opposite the engageable elements, and then holding in the shown configuration until the sheet-form base cools, thereby permanently setting the shape of FIG. 9 . This embodiment acts like a “spring” in that it the fastener component has radial flex which allows the fastener component to be placed onto over-sized objects, for example, protrusions in molds with a larger diameter than the fastener component. [0091] Referring to FIGS. 10-11A , tubular fastener component 100 may be formed by orienting flexible fastener component 10 so that the engageable elements 12 will extend on an outer surface of the finished tubular fastener component. The ends of fastener component 10 are then wrapped and joined as described above. [0092] Now referring to FIG. 12 , fastener system 110 includes tubular fastener component 90 and tubular fastener component 100 , sized such that the fastener component 100 fits inside of fastener component 90 . To more fully appreciate and understand the operation of the fastener system 110 , imagine fastener component 90 fixed in space, for example, extending from a molded part. Fastener component 100 is substantially free to move over fastener component 90 in a direction indicated by arrow 112 . However, when the fastener component 100 is moved in the opposite direction as indicated by arrow 114 , a high shear strength engagement results as the engageable sides 18 of engageable elements 12 of both tubular fastener components 90 and 100 restrict movement in this direction. [0093] Referring to FIG. 13 , a molded-in fastener component 120 is made by embedding tubular fastener compnent 90 in plastic 122 . This is done by placing tubular fastener compnent 90 on protrusion 132 of a mold insert 130 , for example, as shown in FIG. 14 , with engageable elements 12 adjacent the outer surface of protrusion 132 . Mold insert 130 may be a component, for example, of an injection mold or a reaction injection mold (not shown). The plastic 122 that embeds the tubular fastener compnent 90 may be, for example, a thermoplastic or a thermoset. In order to keep tubular fastener compnent 90 on protrusion 132 during cycling of the mold, it can be advantageous to fill the thermoplastic resin 50 ( FIG. 4 ) that will form fastener component 90 with a magnetic material. Further details about filling thermoplastic resin with magnetic materials, for example, a ferro-magnetic filler, are described by Pollard, U.S. Pat. No. 5,945,193, and Kenney, U.S. Pat. No. 6,129,970, the disclosures of which are hereby incorporated in full by reference herein. When tubular fastener components, such as component 90 of FIGS. 13 and 14 , are molded into a substrate, e.g., a foam bun, the height H of the engageable elements is generally minimized to avoid excessive longitudinal intrusion of material into inner portions of the tubular structure. To prevent intrusion, preferably, elements have a maximum height of less than 0.025 inch (0.635 mm), e.g., 0.010 inch (0.254 mm), or less, e.g., less than 0.005 inch (0.127 mm). [0094] Referring to FIG. 14A , and back again to FIG. 14 , in addition to minimizing the height of the engageable elements, another way to minimize intrusion of material longitudinally into inner portions of the tubular structure is to provide a mold protrusion 303 that includes a distal end portion 306 with a diameter larger than a nominal diameter the tubular structure 305 . The tubular structure 305 has an engageable element-free region 307 that seals against distal end portion 306 . The proximal end of protrusion 303 contains a tapered portion 309 for sealing the opposite end of tubular structure 305 . Distal end portion 306 of protrusion 303 includes a tapered lead-in 313 , and a tapered lead-off 311 to allow fastener component 305 to be easily placed onto, and removed from protrusion 303 . [0095] Referring to FIG. 14B , another way to minimize intrusion of material longitudinally into inner portions of a tubular structure is to provide a tubular fastener 320 that includes a resilient material, e.g., an elastomer, that forms a seal 321 at a distal end of the fastener component. The proximal end of the tubular structure 320 is sealed by tapered portion 324 on protrusion 322 , as discussed above. [0096] Radial intrusion of material into inner portions of a tubular structure can be minimized, for example, by longitudinally sealing the tubular structure with an elastomer, or by thermally fusing previously opposite edges. Referring to FIGS. 14C , another method of preventing radial intrusion of material includes overlapping opposite tapered edges 330 . Additional methods of preventing intrusion, and of attaching a fabric cover to a seat cushion, are discussed in “FASTENERS,” filed concurrently herewith, and assigned U.S. Ser. No. ______, the disclosure of which is hereby incorporated in full by reference, herein. [0097] Referring to FIGS. 13A-13C , a fastener component, for example, fastener component 10 of FIG. 1 , is fixed upon support 119 by, for example, using an adhesive, sewing or employing the process for forming fastener components bonded to web materials discussed above. Depending upon how the fastener component is oriented on support 119 , fastener components 121 and 123 of FIGS. 13A and 13B , respectively, can result. Fastener component 127 results from fixing fastener component 121 upon a support 125 , for example, by stitching. Similarly, fastener component 129 is formed by fixing component 123 onto a foam support 126 by, for example, using adhesive or integrally molding component 123 onto 126 . Pushing component 127 into component 129 creates a high shear fastening system. Support 125 may be, for example, a fabric cover and foam support 126 may be, for example, a foam bun that serves as a seat. Various methods of attaching a fabric cover to a seat cushion are described in Roberts, U.S. Pat. No. 5,964,017, Wildem et al., U.S. Pat. No. 5,605,373 and Angell, U.S. Pat. No. 5,499,859, the entire disclosure of each of which is hereby incorporated in full by reference. [0098] Referring to FIGS. 15-16 , another fastening system is illustrated for joining two sheet materials, for example, attaching an extruded plastic stud 140 to a sheet of metal 150 . Referring particularly to FIG. 16 , extruded stud 140 has a plastic male component 142 that is integral with and extends outwardly from one side. While only one male component 142 is shown, plastic stud 140 may have a plurality of such male components 142 . Male component 142 may be formed by extrusion during the same process as making plastic stud 140 or male component 142 may be, for example, adhesive bonded at a later time. Flexible fastener component 10 that is, for example, adhesive-backed is applied to both sides of the plastic male component 142 such that the engageable sides 18 of each of the engageable elements 12 point generally in an downwardly direction, creating male fastener assembly 144 . As an alternative process, male fastener assembly 144 may be, for example, molded as a single, unitary component. Referring particularly to FIG. 15 , sheet metal female assembly 148 includes an extruded plastic female member 146 attached to sheet metal 150 . While only one female member 146 is shown, sheet metal 150 may be attached to a plurality of such components. In addition, female member 146 may be formed, for example, by extrusion and can, therefore, be of considerable length. Flexible fastener component 10 that is, for example, adhesive-backed is applied to both sides of the plastic female member 146 such that the engageable side 18 of each of the engageable elements 12 point generally in an upwardly direction, creating female fastener component 148 . In an alternative embodiment, female fastener assembly 148 may be, for example, molded as a single, unitary component. Referring now to both FIGS. 15 and 16 , to attach extruded plastic stud 140 to sheet metal 150 , male assembly 144 is moved in direction indicated by arrow 152 while keeping female assembly 148 fixed in place. A high shear strength engagement occurs and high force needs to be applied in a direction indicated by arrow 154 to disassemble male assembly 144 from female assembly 148 . [0099] Referring next to FIGS. 17 and 18 , fastener component 139 includes engageable elements 140 similar to those of FIG. 1 , and hooks 142 , 144 extending outwardly from one side of a sheet-form base 146 . In the embodiment shown in FIG. 17 , hooks 142 , 144 extend toward and away from the viewer, respectively. In addition, loops 148 extend outwardly from the same side of the base 146 as the elements 140 . Elements 140 are positioned between hooks 142 , 144 and loops 148 . In some implementations, the elements 140 , 142 and 144 are molded at the same time using a modified version of the process described in FIG. 4 . In this modified process, the mold roll includes a combination of the tooling described above and the tooling described in Fischer, U.S. Pat. No. 4,775,310. Tooling described in Fischer is formed by a face-to-face assembly of thin, circular plates, of thickness, for example, between about 0.004 inch and 0.250 inch (0.010 cm-0.635 cm). Some of the plates, referred to as mold rings, have cutouts in their circular peripheries that define mold cavities while others, referred to as spacer rings, have smooth circular peripheries. The sides of the spacer rings serve to close the open sides of the cutout mold cavities and to serve to create the row spacing between rows of molded features. In some implementations, the loops 148 are bonded to base 146 by using, for example, adhesive. In other embodiments, loops are fed to the nip and melt incorporated. [0100] Referring now to FIG. 18 , a fastener system 149 that has good shear and peel performance may be formed by engaging two fastener components 139 . When a shear force F 1 is directed as shown in FIG. 18 , fastener system 149 exhibits good shear performance due to engageable elements 140 , as discussed above. In addition, when a peel force F2 is directed as shown in FIG. 18 , fastener system 149 exhibits good peel performance due to the engagement of hooks 142 , 144 with loops 148 . [0101] Referring to FIG. 19 , a container 150 includes a top 152 sized to fit onto a bottom 156 . Fixed upon an inside surface of top 152 are engageable elements 154 . Also, fixed upon an outside surface of bottom 156 are engageable elements 158 . The engageable elements 154 , 158 are similar to those shown in FIG. 1 . Engageable elements 154 are fixed upon top 152 such that the elements 154 are oriented with the engageable sides pointing up as shown. Engageable elements 158 are fixed upon bottom 156 such that the elements 158 are oriented with the engageable sides pointing down as shown. To apply or remove top 152 from bottom 156 , engageable elements 154 and vacant portions 157 are aligned, as are engageable elements 158 and vacant portions 155 . Twisting top 152 clockwise or counter clockwise allows top 152 to become “locked” onto bottom 156 as the rows of engageable elements engage one another. Engageable elements 154 , 158 may be fixed using adhesive, or injection molded during the formation of the part. [0102] Referring to FIG. 20 , fastener component 170 includes engageable elements 172 , 174 that extend from portions of sheet-form base 176 , the portions being disposed on opposite sides of base 176 . Fastener component 174 can be made by the process of FIG. 4D or elements 172 , 174 can be bonded to base 176 using an adhesive. Referring to FIG. 20A , elements 172 , 174 are oriented such that upon wrapping base 176 in the manner shown in FIG. 21 , a tubular structure 180 results that includes a dis-engageable, high shear fastener 181 . Fastener component 170 is useful for, for example, holding insulation to pipes. [0103] Referring to FIG. 21 , two pipes 192 , 198 , such as PVC pipes, can be joined by placing engageable elements 194 , 200 on pipes 192 , 198 . Pipe 192 includes a resilient material 196 bonded to a wall that can act as a fluidic seal. Pipe 192 is sized to accept pipe 198 and engageable elements are oriented such that pushing pipe 198 into pipe 192 creates a high shear engagement, similar to that described when discussing FIG. 12 . A fluid tight seal results upon further pushing pipe 198 into pipe 192 as pipe 198 engages and compresses resilient material 196 . In some embodiments, the resilient material is, for example, a thermoset such as a natural rubber. In other implementations, resilient material 196 is, for example, a thermoplastic elastomer such as elastomeric PVC. [0104] Referring to FIG. 22 , a fastener product 600 A includes an array of arcuate engageable elements 630 A integrally molded with, and extending outwardly from a base 615 A. The engageable elements each include an engageable side 633 A, and a non-engageable side 631 A. Both the upper 632 A and lower edges define curves (e.g., circular curves) such that the engageable side 633 A has a curved shape, as descrbed above in reference to FIGS. 1 , 1 A- 1 B, 2 A- 2 B. Similar fasteners are discussed in “FASTENER PRODUCTS,” filed concurrently herewith, and assigned U.S. Ser. No. ______, the disclosure of which is hereby incorporated in full by reference herein. [0105] Referring to FIGS. 22 and 23 , the head element 610 defines an aperture 645 . When the fastener strap 605 is inserted through the aperture 645 , the head element 610 cooperates with the fastener projections 630 A to prevent the strap 605 from retreating back through the aperture 645 . In other words, the head element 610 is configured such that it provides one-way movement through the aperture 645 . The head element 610 includes a retaining arm 658 that extends into the aperture 645 . When the strap 605 is pulled through the aperture 645 in the direction of the arrow, the first surfaces 631 A (non-engageable side) of the wedge-shaped fastener projections 630 A deflect the retaining arm 658 away from the projections 630 A allowing the strap 605 to proceed through the head element 610 . However, when the strap 605 is pulled in a direction opposite to that shown by the arrow, the second surface 633 A (engageable side) of the projection 630 A abuts and engages the retaining arm 658 . This prevents the strap 605 from exiting the head element 610 . The fastener product shown in FIG. 23 can be used to retain articles (e.g., tubes or pipes) in a bundle. Similarly, they can be used to suspend an article or articles from a beam or other structure. In addition, the fastener products can be useful as a human restraint mechanism (e.g., handcuffs). They can be wrapped around the wrists or ankles of a person and tightly fastened to restrain the person. [0106] Referring to FIG. 24 , an apparatus is shown that can be used to produce the fastener product shown in FIG. 22 . Mold roll 215 includes multiple lanes of molding cavities 252 arranged across its transverse direction. Each lane of molding cavities is circumferentially separated along the mold roll 215 such that the fastener product sheet molded, when molten resin is delivered to nip N by die 205 connected to an extruder, includes multiple, longitudinally separated lanes of fastener projections. In other embodiments, the mold roll can include a continuous array of molding cavities spanning the circumferential surface of the mold roll. The mold roll 215 also includes multiple, circumferentially spaced molding recesses 250 . As a result, the fastener product sheet molded in the process includes multiple, longitudinally spaced apart head elements and/or holes defined by the head elements. [0107] Referring to FIG. 24 , the mold roll 215 includes wedge-shaped molding cavities 252 to mold wedge-shaped fastener projections. The cavities 252 include a first planar surface that extends inward from the peripheral surface of the mold roll 215 at a decline relative to the peripheral surface. The cavities 252 include a second surface that extends inward at a decline substantially steeper than the decline of the first surface. The first and second surfaces join together at their distal ends within the cavities 252 . In some embodiments, the second surface is curved to form a projection having a curved wall. [0108] Referring to FIG. 25 , the molding recesses 250 include an outer recessed portion 271 to form the head element and an inner unrecessed portion 272 to form the hole within the head element. The inner unrecessed portion 272 includes a recess 273 that extends inward at an angle relative to the side surfaces of the head elements for forming the restraining arm that extends from the head element. In the embodiment discussed above, the molding cavities 252 and recesses 250 are each located in the mold roll 215 . In alternative embodiments, the pressure roll 220 can define the molding recesses 250 and cavities 252 . Similarly, the recesses 250 and cavities 252 can be located, in various combinations, in both the mold roll 215 and the pressure roll 220 . [0109] Referring to FIG. 26 and 27 , a fastener product sheet 640 formed using the apparatus shown in FIG. 17 includes a central region 655 and two end regions 660 , 665 . The central region 655 includes a base 615 from which multiple horizontal lanes of fastener projections 630 A extend. The edge regions 660 , 665 include longitudinally spaced head elements 610 that define longitudinally spaced holes or apertures 645 . The fastener product sheet 640 can be separated along predetermined frangible boundaries 699 (e.g., perforated regions) to create multiple, discrete fastener products similar to the fastener product 600 A shown in FIG. 22 . Any of the separating methods discussed above can be used to create the discrete fastener products [0110] Referring to FIG. 28 , a tubular fastener component 350 includes a resilient material 356 , e.g., a foam, or an elastomer, sandwiched between a tubular structure 354 , and a base 352 that includes array of wedge-shaped, engageable elements extending from a first side 352 . The second side 362 of base 352 is bound to the compliant material 356 , e.g., is integral with, or is bound with an adhesive. The array of wedge-shaped, engageable elements each have an engageable side 364 , and a non-engageable side 366 , like those shown in FIG. 1 . Structurally rigid tubular fastener component 370 with has a wall from which wedge-shaped, engageable elements extend. The orientation of the engageable elements that extend from component 370 are generally opposite of those of component 350 . The outer diameter of component 350 is oversized relative to the inner diameter of component 370 . When component 350 is inserted into component 370 in direction 372 , the resilient material allows for radial flex of the engageable elements in directions 371 , 373 as they slide past the engageable elements of component 370 , springing back into regions 374 . This spring-type action ensures good engageability of the engageable elements. [0111] Other embodiments have also been considered. For example, while fastener components having identical elements have been shown in the figures and discussed above, in some cases the fastener components may include elements having different geometries. While hollow tubular components having fastener elements on their inner and outer surfaces have been shown and discussed above ( FIG. 11 ), a solid, injection molded male part in some cases is advantageous. The hooks in the embodiment shown in FIG. 17 may be oriented differently. For example, the hooks may all be oriented in the same direction. [0112] Other embodiments are within the scope of the following claims.

A fastener element with a sheet-form base and an array of wedge-shaped engageable elements molded integrally with a surface of the sheet-form base. The wedge-shaped elements each have a steep side and a gradually rising side, and are arranged with their steep sides all directed in a common sense, such that the array can engage a similar array of oppositely-directed wedge-shaped elements to resist shear motion. The distal edges of the wedges are curved in top view.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a charged particle beam apparatus with a power source unit of a high voltage and a high power output, which is capable of instantaneous self-restoration of a load-short-circuit caused by an electric discharge. 2. Description of Prior Art FIG. 5 is a diagram showing the construction of an electron-beam welding apparatus as an example of conventional apparatuses. In FIG. 5, a reference numeral 1 designates a controllable power source for an inverter, a numeral 2 designates a booster transformer connected to the output side of the controllable power source 1, a numeral 3 designates a rectifying circuit to rectify an alternating current output from the controllable power source 1, a numeral 4 designates a smoothing reactor, a numeral 5 designates a smoothing capacitor, a numeral 6 designates a cathode of a welding machine, a numeral 7 designates an anode of the welding machine, a numeral 8 designates an electron beam emitted from the cathode 6, a numeral 9 designate a Wehnelt electrode for controlling the current intensity of the electron beam 8, a numeral 10 designates a workpiece irradiated by the electron beam 8, a numeral 11 designates a controllable biasing power source which applies a voltage to the Wehnelt electrode 9, a numeral 12 designates an insulating transformer which supplies a power to the controllable biasing power source 11 to keep it at a high potential, a numeral 13 designates a detecting resistor to detect beam accelerating voltage V A , a numeral 14 designates a constant-voltage controlling circuit for the beam accelerating voltage V A , a numeral 15 designates a detecting resistor to detect a power source current I K , a numeral 16 designates a constant-current controlling circuit for the power source current I K , a numeral 17 designates optical fibers for transmitting an output of the constant-current controlling circuit 16 to the controllable biasing power source 11 at a high potential, and a numeral 18 designates a load-short-circuit (hereinbelow referred to as arcing) produced between the anode 7 and the Wehnelt electrode 9 or the cathode 6. FIG. 6 is a diagram showing the construction of the constant-voltage controlling circuit 14 or the constant-current controlling circuit 16. In FIG. 6, a reference numeral 19 designates a feedback signal supplied from the detecting resistor 13 for the beam accelerating voltage V A or the detecting resistor 15 for the power source current I K , a numeral 20 designates a low-pass filter for removing noises contained in the feedback signal, a numeral 21 designates a set signal, a numeral 22 designates a comparator for comparing the feedback signal 19 with the set signal 21, and a numeral 23 designates a controlled signal. FIGS. 7 and 8 respectively show voltage and current waveforms appearing at each part of the apparatus when the arcing 18 takes place. In FIGS. 7 and 8, a symbol V A represents a beam accelerating voltage, a symbol I O represents a power source output current of the controllable power source 1, which is shown by an envelope of the peaks of a high frequency waveform, a symbol I K represents a power source current, a symbol I C represents a beam current, symbols t represent time, a reference numeral 24 represents generation of the first arcing, a numeral 25 represents generation of the second arcing and a numeral 26 represents interruption of the power source. FIG. 9 shows a defect in a weld bead due to generation of the arcing, in which a reference numeral 27 designates a configuration of the surface of the weld bead, a numeral 28 designates a weld line, and a numeral 29 designates a longitudinal cross-sectional view of the weld bead. The operation of the conventional control system for a charged particle beam apparatus will be described with reference to FIGS. 5 to 9. In FIG. 5, an electric power supplied from the controllable power source 1 is stepped up in the booster transformer 2, then rectified by the rectifying circuit 3 and thereafter, smoothed by the smoothing reactor 4 and the smoothing capacitor 5. The smoothed power is supplied across the cathode 6 and the anode 7, thus resulted electron beam 8 irradiating the workpiece 10. The current intensity of the electron beam 8 is controlled by a biasing voltage of the controllable biasing power source 11, which is applied across the Wehnelt electrode 9 and the cathode 6. The biasing voltage is supplied from the insulating transformer 12 and the controllable biasing power source 14 and is overlapped to the beam accelerating voltage V A . The controllable biasing power source 11 is controlled by, for instance, optical fibers 17. The beam accelerating voltage V A is detected by the detecting resistor 13 for the beam accelerating voltage V A to be controlled by the constant-voltage controlling circuit 14. The beam current I C (which is equivalent to the power source current I K under the condition other than generation of arcing) is detected by the detecting resistor 15 for the power source current I K to be controlled by the constant-current controlling circuit 16. Control of constant voltage and constant current is performed in such a manner that as shown in FIG. 6, difference between the feedback signal 19 and the set signal 21 is detected by the comparator 22 and a controlled signal 23 as an output of the comparator 22 is used so that the feedback signal 19 and the set signal 21 become equal by changing, for instance, a duty of an inverter when the beam accelerating voltage V A is controlled, or by changing the biasing voltage of the controllable biasing power source 11 through the optical fibers 17 when the power source current I K is controlled. In this case, when a welding operation is carried out, metallic vapor produced from a molten part of the workpiece 10 flows in a space between the anode 7 and the cathode 6 or the Wehnelt electrode 9, whereby there frequently causes arcing 18 due to a short circuit between both the electrodes. The arcing 18 in vacuum condition occurs with pulsation and is completed in about 100 μs. FIG. 7 shows voltage and current waveforms appearing specified parts in the welding machine at the time of generation of the arcing 18. The beam accelerating voltage V A once becomes zero volt when generation of the arcing 18 is finished since there is no electric charge in the smoothing capacitor 5. However, the power source output current I O of the controllable power source 1 is rapidly increased owing to the constant-voltage control and both the beam accelerating voltage V A and the power source output current I O are largely changed by a time constant (several m sec.) determined by the smoothing reactor 4 and the capacitor 5. In addition, when the arcing 18 takes place, an arcing current having a high peak value is overlapped on the power source current I K which is detected to control the beam current I C . Accordingly, the constant-current controlling circuit 16 functions so as not to flow the beam current I C even though there is in fact no beam current I C . Accordingly, the power source current I K and the beam current I C largely varies after generation of the arcing 18 by the influence of the change in the beam accelerating voltage V A . Thus, when the arcing 18 is once generated, the control of voltage and current becomes unstable in transition time and high voltage and current are produced. Accordingly, the second arcing 18 and the third arcing 18 are produced as shown in FIG. 8, and the output current I O of the controllable power source 1 is remarkably increased, whereby an interruption circuit for the controllable power source 1 is actuated to stop the welding operation. FIG. 9 shows a configuration of the weld bead when the arcing 18 takes place. When the arcing 18 is once generated, the beam accelerating voltage V A and the beam current I C are largely changed even though the power source does not stop. As a result, the width of the bead and the depth of penetration are largely varied. Particularly, when the power source is suddenly stopped due to generation of the arcing 18, molten metal is not supplied to a thin and deep hole formed by the electron beam to fill it to thereby create a deep crater. Repair of the crater is troublesome. To improve unstableness in a control system caused by generation of the arcing, it is considered that the frequency of the low-pass filter 20 is reduced with respect to the feedback signal 19 so that response of the control system becomes sufficiently slow, whereby interruption for the power source is delayed. However, this method sacrifices controllability of the beam accelerating voltage V A and the beam current I C in normal condition. There has been employed a method in which an irradiation path of the electron beam 8 is curved by means of a magnetic field to thereby reduce the metallic vapor entering in the space between the cathode 6 and the anode 7. However, it has been impossible to reduce the probability of generation of the arcing to zero. SUMMARY OF THE INVENTION It is an object of the present invention to provide a control system for a charged particle beam apparatus which does not bring about the stoppage of a power source due to increase in a beam accelerating voltage and a beam current in spite of generation of arcing, whereby defect in a workpiece can be avoided. The present invention is to provide a control system for a charged particle beam apparatus which comprises a controllable power source for feeding a power to a beam generating part, the controllable power source being subject to feedback control in response to a beam accelerating voltage, wherein when a load-short-circuit takes place due to an electric discharge, a feedback signal in a feedback control line is fixed at a predetermined value corresponding to the feedback signal under the condition before occurrence of the load-short-circuit, and then, the fixed feedback signal is released to continue the feedback control. Another aspect of the present invention is to provide a control system for a charged particle beam apparatus which comprises a controllable power source for feeding a power to a beam generating part, the controllable power source being subject to feedback control in response to a beam accelerating voltage, wherein when a load-short-circuit takes place due to an electric discharge, a feedback signal in a feedback control line is fixed at a predetermined value corresponding to the feedback signal under the condition before occurrence of the load-short-circuit; thereafter, the fixed feedback signal is released for the continuation of the feedback control, and application of the beam accelerating voltage is stopped at the time of load-short-circuiting, followed by reopening the application of the beam accelerating voltage before continuing the feedback control. Another aspect of the present invention is to provide a control system for a charged particle beam apparatus which comprises a controllable power source for feeding a power to a beam generating part, the controllable power source being subject to feedback control in response to a beam accelerating voltage and a controllable biasing power source in the beam generating part, which is subject to feedback control by a power source current flowing in a power feeding circuit of the controllable power source, wherein when a load-short-circuit takes place due to an electric discharge, a feedback signal in each feedback control line for the controllable power source and the controllable biasing power source is fixed at a predetermined value corresponding to each of the feedback signals under the condition before occurrence of said load-short-circuit, and then, each of the feedback signals is released to continue the feedback control. Still another aspect of the present invention is to provide a control system for a charged particle beam apparatus which comprises a controllable power source for feeding a power to a beam generating part, the controllable power source being subject to feedback control in response to a beam accelerating voltage and a controllable biasing power source in the beam generating part, which is subject to feedback control by a power source current flowing in a power feeding circuit of the controllable power source, wherein when a load-short-circuit takes place due to an electric discharge, a feedback signal in each feedback control line for the controllable power source and the controllable biasing power source is fixed at a predetermined value corresponding to each of the feedback signals before occurrence of the load-short-circuit; thereafter, each of the feedback signals is released to continue the feedback control, and application of the beam accelerating voltage is stopped at the time of the load-short-circuiting, followed by reopening the application of the beam accelerating voltage before continuing the feedback control. BRIEF DESCRIPTION OF DRAWING FIG. 1 is a diagram of an embodiment of a control circuit for a beam accelerating voltage and a power source current of the present invention; FIG. 2 is waveforms of the voltage and current appearing at specified parts in FIG. 1 when a load-short-circuit occurs; FIG. 3 is a diagram of another embodiment of the control circuit for a beam accelerating voltage and a power source current according to the present invention; FIG. 4 shows waveforms of voltage and current appearing at specified parts in FIG. 3 when a load-short-circuit occurs; FIG. 5 is a diagram showing a construction of a conventional electron beam welding machine; FIG. 6 is a diagram of a conventional control circuit for a beam accelerating voltage and a power source current; FIGS. 7 and 8 respectively waveforms of voltage and current appearing at specified parts of the conventional apparatus when a load-short-circuit occurs; and FIG. 9 is a schematic view showing defect of weld bead caused by generation of load-short-circuit in the conventional apparatus. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to drawing. FIG. 1 is a diagram of the constant-voltage and constant-current control circuit of an embodiment according to the present invention. FIG. 1 is a diagram showing the construction of a constant-voltage and constant-current control circuit. A reference numeral 19a designates a feedback signal from a power source current I K , a numeral 19b designates a feedback signal from a beam accelerating voltage V A , a numeral 20a designates a low-pass filter for the feedback signal 19a of the power source current, a numeral 20b designates a low-pass filter for the feedback signal 19b of the beam accelerating voltage V A , a numeral 30 designates a detecting circuit for detecting generation of arcing 18 according to the feedback signal 19b of the beam accelerating voltage V A , a numeral 31 designates a trigger pulse output from the detecting circuit 30 as soon as the arcing 18 takes place, a numeral 32 designates a monostable multivibrator actuated by the trigger pulse 31, a numeral 33 designates a pulse-width determining device for the monostable multivibrator 32, a numeral 34a designates a sampling-hold circuit for the feedback signal 19a of the power source current I K , a numeral 34b designates a sampling-hold circuit for the feedback signal 19b of the beam accelerating voltage V A , and a symbol V H indicates a holding signal which is output from the monostable multivibrator 32 to keep the sampling-hold circuits 34a, 34b inactive. A symbol V AO indicates an output signal of the sampling-hold circuit 34b, a symbol I KO indicates an output signal of the sampling-hold circuit 34a, numerals 21a and 21b indicate set signals, a numeral 22a designates a comparator for comparing the output signal of the sampling-hold circuit 34a with the setting signal 21a, a numeral 22b designates a comparator for comparing the output signal of the sampling-hold circuit 34b with the setting signal 21b, a numeral 23a designates a controlled signal of the power source current I K and a numeral 23b is a controlled signal of the beam accelerating voltage V A . FIG. 2 shows voltage and current waveforms appearing at specified parts of the welding machine according to the present invention when the arcing 18 takes place. FIG. 1 is a circuit diagram of an embodiment of the present invention, which corresponds to the constant-voltage control circuit 14 and the constant-current control circuit 16 as shown in FIG. 5. The construction other than the control circuits 14, 16 can be employed for the embodiment of the present invention. The operation of the embodiment of the present invention will be described with reference to FIGS. 1 to 4. On generation of the arcing 18, the beam accelerating voltage V A and the power source current I K suddenly vary. Accordingly, when the feedback signal 19b of the beam accelerating voltage V A is input to the detecting circuit 30 composed of a comparator or a differential circuit to detect generation of the arcing, the trigger pulse 31 indicative of the generation of the arcing 18 is produced. When the monostable multivibrator 32 receives the trigger pulse 31, it generates the holding signal V H for the sampling-hold circuits 34a and 34b whereby the feedback signal 19a of the power source current I K and the feedback signal 19b of the beam accelerating voltage V A are held. In this case, it is unnecessary for the feedback signal 19b to be passed through the low-pass filter 20b because the detecting circuit 30 deals the feedback signal 19b having a large variation quantity of the generation of arcing 18 and therefore, the function of the detecting circuit 30 is not influenced even though there is some quantity of noise. Accordingly, the holding signal V H is quickly input in the sampling-hold circuits 34a, 34b whereby the feedback signal 19a of the power source current I K and the feedback signal 19b of the beam accelerating voltage V A having respective values at the time of generation of the arcing 18 can be held (the level of signals is substantially at the value just before generation of the arcing 18 because the low-pass filters 20a, 20b are provided). In other words, when the arcing 18 is generated, control is carried out by the feedback signals 19a, 19b having normal values just before generation of the arcing 18, and the quantity of sudden change in the beam accelerating voltage V A and the power source current I K after generation of the arcing 18 is neglected. Accordingly, a control system of this embodiment can be operated in a stable manner. The beam accelerating voltage V H is returned to the normal condition within several ms although time of return is determined by a time constant given by the smoothing reactor 4 and the smoothing capacitor 5. Accordingly, holding time can be determined to be 20 ms by adjusting the pulse-width determining device 33. Namely, the control circuit of the present invention is operated in such a manner that when arcing 18 takes place, change in control is made from an ordinary feedback control to an open control in which data just before generation of the arcing 18 is used, and the feedback control is again initiated after the beam accelerating voltage V A and the power source current I K are returned to substantially normal values. Even though there is generally large variation in the open control, the open control according to this embodiment is based on data of feedback control just before generation of the arcing 18, and further, the period of the open control is short as much as several tens ms or less. Accordingly, the open control of this embodiment is highly accurate as the feedback control. FIG. 2 shows voltage and current waveforms. When the arcing 18 takes places, the sampling-hold circuits 34a and 34b are actuated. A beam accelerating voltage signal V AO and a power source current signal I KO input in a control circuit do not show substantial change and the beam accelerating voltage V A and the power source current I K are smoothly returned to normal condition. A slight change occurs when the feedback control is started again in order to correct errors resulted in the open control. Accordingly, the output current I O of the controllable power source 1 does not substantially change and there causes no interruption of the controllable power source 1. In this embodiment, the beam accelerating voltage V A and the beam current I C are interrupted for about 10 ms. However, when the speed of welding in typical 6 kW and 100 kW welding machines are respectively determined to be 1 m/min and 0.3 m/min, the distance of movement of electrode in the interruption time of the beam accelerating voltage V A and the beam current I C are respectively 170 μm and 50 μm. Accordingly, no defect is found in welded portion even though there is a trace on the surface of a weld bead. In the above-mentioned embodiment, a control system is constituted by the sampling-hold circuit 34b for the feedback signal 19b of the beam accelerating voltage V A and the sampling-hold circuit 34a for the feedback signal 19a of the power source current I K . However, the object of the present invention can be attained by constructing the control system by only the sampling-hold circuit 34b for the feedback signal 19b of the beam accelerating voltage V A . The values of the feedback signals 19a and 19b are not always the same as values just before generation of the arcing 18. The same effect can be obtained by a value lower than a value just before generation of the arcing 18 due to the delay of the holding signal V H . In the above-mentioned embodiment, the controllable power source 1 which may be a power source for an inverter is actuated even if the arcing 18 takes place. However, it may be such construction as shown in FIG. 3 that the power source is instantaneously stopped. This construction is effective in the case that the operational frequency of the inverter is so high that the arcing 18 of, for instance, about 100 μs to about 1 ms may occurs again when the beam accelerating voltage V A is immediately returned to normal condition. In FIG. 3, when the trigger pulse 31 indicative of generation of the arcing 18 is input another monostable multivibrator 32c, a pulse V S is produced to instantaneously stop the inverter. Preferably, the time for stopping the inverter is determined by adjusting the pulse-width determining device 33c so as to be several ms. The outputs of a PID (proportion-integration-differential) circuit 35 for giving constant-voltage control to the beam accelerating voltage V A and a PWM (pulse-width-modulation) circuit 36 is instantaneously interrupted by a pulse V S for instantaneously stopping an inverter. Accordingly, it is possible to stop supply of the beam accelerating voltage V A for a suitable time as shown in a waveform in FIG. 4. In the above-mentioned embodiment, data of the feedback signal 19 in the condition just before generation of the arcing 18 is held by utilizing time delay of the feedback signal 19 by means of the low-pass filter 20. However, it is possible to use the pre-trigger function of a digital type waveform memory device in which the feedback signal 19 is successively written in a RAM, and data in the condition just before generation of the arcing 18 can be read out when the trigger pulse 31 is input. Description has been made as to a control system for an electron beam welding machine as an example of the present invention. However, the same effect can be obtained in a charged particle beam apparatus of a high voltage, e.g. an ion implantation device. In this case, it is possible to minimize adverse affect against a workpiece during arcing. As stated above, the control system for a charged particle beam apparatus of the present invention is so constructed that when generation of arcing is detected, feedback signals of the beam accelerating voltage and the power source current are held at predetermined values corresponding to the feedback signals in the condition just before generation of the arcing and open control is carried out for several tens ms until the beam accelerating voltage and the power source current are returned to normal condition, and thereafter, feedback control of a high speed is restarted. Accordingly, the control system is operated in a stable manner even in the arcing and the controllable power source can be automatically returned within a short time whereby any defect takes place in the workpiece which is subject to irradiation of the electron beam.

A feedback signal of a beam accelerating voltage, which is input into a feedback control system is fixed at a predetermined value corresponding to a signal under the condition before generation of arcing, when the arcing is generated, and thereafter, the fixed feedback signal is released to continue a feedback control.

BACKGROUND OF THE INVENTION This invention relates to an ignition coil unit for an internal combustion engine and, more particularly, to an ignition coil unit in which an ignition coil and a power switch for controlling a primary current through the ignition coil are integrally combined into a unit. FIG. 4 is an electrical circuit diagram of a known ignition coil unit for an internal combustion engine. The ignition coil unit comprises an ignition coil A having a primary winding 2 and a secondary winding 6, and a power switch circuit B having a plurality of electric and electronic circuit components. In FIG. 4, it is also seen that an electric source C and an ignition signal control circuit D are connected to the ignition coil unit. The power switch circuit B comprises a power transistor 1 for switching a primary current flowing through the primary winding 2 of the ignition coil A, a current limiting circuit 4 and a current detecting circuit 3 for detecting a potential difference generated by the primary current and for transmitting a primary current control signal to the current limiting circuit 4. FIG. 5 is a front view of the known ignition coil unit before it is filled with insulating resin, and FIG. 6 is a sectional side view of the ignition coil unit illustrated in FIG. 5 in which the ignition coil A and the power switch circuit B are integrally combined. In FIGS. 5 and 6, the secondary winding 6 of the ignition coil A is disposed within a casing 5 and concentrically wound around the primary winding 2 of the ignition coil A and an iron core 7. Thus, the ignition coil A is composed of the primary winding 2, the secondary winding 6 and the iron core 7. The iron core 7 is substantially C-shaped member having a pair of substantially U-shaped members welded together at an end of one of the legs of the U positioned in an opposing relationship. An air gap 7a is defined between opposing legs of the U-shaped members. One leg 7b of each of the U-shaped members is much longer than the other leg 7c and the air gap 7a is not centrally located with respect to the ignition coil A. A heat dissipating plate 22 made for example of aluminum is disposed in the casing 5 and a packaged power switch circuit 23 having the power switch circuit B therein is attached to the heat dissipating plate 22. The packaged power switch circuit 23 comprises a mold resin, 23a hermetically sealing and packaging the power switch circuit B into a single unitary piece by the transfer molding. A connector 8 is integrally molded with the casing 5. As illustrated in FIG. 6, an electrically insulating resin 9 is filled within the casing 5. As seen from FIGS. 5 and 6, the connector 8 has a plurality of connector terminals 11, 13, 15, 18. The first connector terminal 11 is electrically connected to the one end of the secondary winding 6 through a secondary winding ground line 10 and the second connector terminal 13 is electrically connected to the one end of the primary winding 2 through a source line 12. The third connector terminal 15 is electrically connected to a base terminal 16 of the power transistor 1 (See FIG. 4) in the power switch circuit B within the packaged power switch circuit 23 through a control signal line 14. The fourth connector terminal 18 is electrically connected to a ground terminal 19 of the power switch circuit B through a ground line 17. A collector terminal 21 of the power transistor 1 is electrically connected to the other end of the primary winding 2 through a collector line 20. In the known ignition coil unit as described above, the primary current of the primary winding 2 flows through the current detection circuit 3, where the current level is detected as the potential difference upon which a control signal is supplied to the current limiting circuit 4. The current limiting circuit 4 controls the primary current flowing through the primary winding 2 of the ignition coil A in accordance with this control signal. In response to this primary current flowing through the primary winding 2, a high voltage to be supplied to a distributor (not shown) is generated in the secondary winding 6 of the ignition coil A. With the known ignition coil unit as described above, after the packaged power switch 23 and the primary and secondary windings 2, 6 are mounted within the casing 5, electrical connections such as the connections between the connector terminals 11, 15, 18, 13 of the connector 8, the primary and secondary windings 2, 6 of the ignition coil A and the power switch circuit B must be provided through separate electrical conductors 10, 12, 14, 17, 20 within the limited space in the casing 5. Therefore, the ignition coil unit cannot be easily and speedily assembled, and these connecting portions sometimes fail to be tightly and correctly connected, and thus may be easily damaged. SUMMARY OF THE INVENTION Accordingly, one object of the present invention is to provide an ignition coil unit for an internal combustion engine free from the above-discussed problems of the known ignition coil unit. Another object of the present invention is to provide an ignition coil unit which can be easily assembled and reliable. A further object of the present invention is to provide an ignition coil unit which simplifies the connecting processes between the ignition coil and the power switch circuit. With the above objects in view, the ignition coil unit of the present invention comprises a coil assembly having an ignition coil, a power switch circuit having a plurality of electric and electronic components therein for interrupting an electric current flowing through the ignition coil and a terminal conductor for electrically connecting the coil assembly to an external circuit, and an electrically insulating transfer-molded resin disposed around the coil assembly for supporting therein the coil assembly. Further, the ignition coil, the power switch circuit and the terminal conductor are mechanically connected into the coil assembly. The present invention also resides in a method for manufacturing an ignition coil unit, comprising the steps of preparing an ignition coil and a power switch circuit having a plurality of electric and electronic components therein for interrupting an electric current flowing through the ignition coil, electrically connecting the power switch circuit and the ignition coil into a coil assembly and transfer-molding an electrically insulating resin around the coil assembly for hermetically sealing and supporting therein the coil assembly. The method further comprises the step of mechanically connecting the ignition coil and the power switch circuit together. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more readily apparent from the following detailed description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings, in which: FIG. 1 is an exploded perspective view illustrating one embodiment of an ignition coil unit of the present invention; FIG. 2 is a perspective view of the ignition coil unit illustrated in FIG. 1; FIG. 3 is a sectional view of the ignition coil unit illustrated in FIGS. 1 and 2; FIG. 4 is a circuit diagram of a known ignition coil to which the present invention is applicable; FIG. 5 is a front view of a known ignition coil unit before it is filled by a filler resin; and FIG. 6 is a sectional view of a known ignition coil unit illustrated in FIG. 5. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 illustrate an embodiment of an ignition coil unit of the present invention which comprises an electrically insulating transfer-molded resin 50 and a coil assembly 55 disposed within the transfer-molded resin 50. The coil assembly 55 is composed of an ignition coil A and a power switch circuit 30 which are mechanically and electrically connected to each other as illustrated in FIG. 3 showing a sectional view of the ignition coil unit. The power switch circuit 30 comprises a plurality of electric and electronic components (not shown) which compose the power switch circuit B illustrated in FIG. 4 including the power transistor 1 and the current limiting circuit 4 and the like. The power switch circuit 30 also comprises a mold resin for hermetically sealing therein these electric and electronic components. In this embodiment, the power switch circuit 30 which is previously molded with the mold resin, that is, the packaged power switch circuit 30 as illustrated in FIGS. 1 and 3 is used. However, the non-packaged power switch circuit which is not molded may be used. The ignition coil A has a primary winding 2 and a secondary winding 6 concentrically wound around the primary winding 2. Inserted into the primary winding 2 is an iron core 7 and the substantially C-shaped iron core 7 has a pair of substantially U-shaped members 71, 72 which are welded together at an end of one of the legs of the U positioned in an opposing relationship. As illustrated in FIG. 3, one leg 7b of the iron core 7 is much longer than the other leg 7c and an air gap 7a between the legs 7b and 7c is not centrally located with respect to the ignition coil A, but is positioned close to one of axial ends of the ignition coil A. Then, as the packaged power switch circuit 30 is relatively remote from the air gap 7a, a heat generated at the air gap 7a does not affect the packaged power switch circuit 30. As illustrated in FIG. 1, the packaged power switch circuit 30 is mounted on a holder 35 and supported by means of a pair of supporting plates 36 extending upwardly from the bottom of the holder 35 along the opposite side surfaces of the packaged power switch circuit 30. Disposed between the packaged power switch circuit 30 and the holder 35 is a heat dissipating plate 34 made for example of aluminum and attached to the packaged power switch circuit 30. The packaged power switch circuit 30 may be, if necessary, covered with cover means 30a such as a silicone sheet for protecting from and absorbing stress caused therebetween. The packaged power switch circuit 30 has a base terminal 31, a ground terminal 32 and a collector terminal 33 which extend outwardly from the mold resin of the packaged power switch circuit 30 and are partitioned by partition walls 37 provided to the holder 35. The partition walls 37 extend from the holder 35 parallel to the terminals 31, 32, 33. A connector 8 is integrally molded with the casing 50 as illustrated in FIG. 2. The connector 8 has a plurality of connector terminals 40, 41, 42, 43, 44. The first connector terminal 40 is electrically connected to the one end of the secondary winding 6 and the second connector terminal 41 is electrically connected to the one end of the primary winding 2 and the third connector terminal 42 is electrically connected to the base terminal 31 of the packaged power switch circuit 30. The fourth connector terminal 43 is electrically connected to the ground terminal 32 of the packaged power switch circuit 30. The terminal 44 electrically connects the collector terminal 33 of the packaged power switch circuit 30 to the other end of the primary winding 2. As illustrated in FIG. 3, a secondary terminal 45 is electrically connected to the other end of the secondary winding 6 for supplying a high voltage generated in the secondary winding 6 to the distributor (not shown). The secondary terminal 45 comprises an outer case 45a illustrated in FIG. 2 which can be integrally manufactured by the transfer-molding at the time when the transfer-molded resin 50 is manufactured. Thus, the packaged power switch circuit 30 and the ignition coil A are electrically connected to each other through these terminals. As illustrated FIG. 1, the holder 35 has a recessed coupler 46 for receiving a projection 47 provided on the ignition coil A. The projection 47 has a substantially T-shaped cross-section and snugly fit into the recessed coupler 46 so that a relatively firm mechanical connection is established between the holder 35 and the ignition coil A. Therefore, the ignition coil A and the packaged power switch circuit 30 are mechanically connected to each other through the holder 35. In the manufacture of the ignition coil unit of the present invention as described above, firstly, the packaged power switch circuit 30 and the ignition coil A are mechanically connected to each other by means of the recessed coupler 46 of the holder 35 and the projection 47 of the ignition coil A. Next, the terminals 31, 32, 33 of the packaged power switch circuit 30, the primary and secondary windings 2, 6 of the ignition coil A, the connector terminals 40, 41, 42, 43, 44 and the secondary terminal 45 are electrically connected to each other to assemble the united coil assembly 55 as illustrated in FIG. 3. The united coil assembly 55 is placed and suitably supported within a mold die (not shown) so that an electrically insulating resin 50 is transfer-molded around the coil assembly 55. The transfer-molded resin 50 is formed into a configuration corresponding to the casing 5 of the unit illustrated in FIGS. 5 and 6 and comprises a main body portion accommodating the ignition coil A and the power switch circuit 30, a connector portion defining the connector 8 for external connection, and a tower portion defining the secondary terminal 45 as illustrated in FIG. 3. According to the ignition coil unit of the present invention as described above, since the packaged power switch circuit is electrically connected to the ignition coil A through the terminals and mechanically assembled into the united coil assembly 55 before they are molded within the molded resin 50, all electrical connections between them can be very easily carried out. Hence, the electrical connection processes between them becomes easy and the connecting portions can be correctly and tightly connected. Therefore the ignition coil unit of the present invention can be easily assembled and reliable. Further, the manufacture processes are improved to be efficient.

An ignition coil unit comprises a coil assembly (55) having an ignition coil (A), a power switch circuit (B) having a plurality of electric and electronic components therein for interrupting an electric current flowing through the ignition coil (A) and a terminal conductor (8) for electrically connecting the coil assembly (55) to an external circuit, and an electrically insulating transfer-molded resin (50) disposed around the coil assembly (55) for supporting therein the coil assembly (55). Further, the ignition coil (A), the power switch circuit (B) and the terminal conductor (8) are mechanically connected into the coil assembly (55). The present invention also resides in a method for manufacturing the same.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical control unit for controlling the schedule run of an NC machine tool. 2. Description of the Conventional Art The automatic timed control of scheduled events is a goal desired in many fields. For example, as disclosed in Laid Open Japanese Patent Publication 1-96003, the scheduling control of various units of lighting areas, energizing motors and operating various systems in buildings or factories is provided. Such goal also is desired in the automatic manufacture of products comprising one or more workpieces, including manufacture by numerical control. Conventionally, a NC machine tool is controlled by a machining program, which gives the machine tool instructions with respect to the machining of a locus on a workpiece, machining conditions and the like, and responds to a variety of input data which may be stored or registered. The sequence of reading registered information concerning the program run sequence, the number or run times, run start time, etc. for the machining program (hereinafter "machining schedule data"), the reading of registered information for a measurement program which gives a machine tool instructions in regards to measurement locus and measurement conditions and the like (hereinafter "measurement schedule data"), and the running of the machine tool in accordance with the machining schedule data and measurement schedule data is commonly called a "schedule run" of the program. FIG. 16 is a hardware configuration diagram of a conventional numerical control unit for performing a schedule run process, as disclosed in Japanese Patent Publication No. 200409 of 1989. FIG. 17 shows an example of a machining program file directory screen for the conventional numerical control unit. FIG. 18 illustrates a scheduling data screen example of the conventional numerical control unit. An embodiment of the conventional art may be described in accordance with the drawings. First the hardware configuration example may be described with reference to FIG. 16, illustrating the hardware configuration of the known numerical control unit. In FIG. 16, a processor (CPU) 111 is used for controlling the whole numerical control unit via a common bus 126 in a conventional system architecture. A ROM 112 storing a control program, a RAM 113 storing various types of data, and a non-volatile storage 114, such as a bubble memory, storing various types of data, parameters, etc, are all accessible by the CBU via the system bus 126. Within memory 114 is scheduling data 114a for determining the machining programs that are to be employed for scheduling runs and the sequence of program execution. Also connected to the system bus is a tape reader 115, used for reading a machining program, etc. from a paper tape, a display control circuit (CRTC) 116 for converting a digital signal into a display signal, a display device 116a, such as a CRT or a liquid crystal display device, and a keyboard 117 for entering various types of data. The operational elements connected to the bus include a position control circuit 118 for controlling a servo motor. Circuit 118 connects to a servo amplifier 119 for controlling servo motor velocity, of a servo motor 120. A tacho-generator 121 is used for velocity feedback, and a position detector 122, such as a pulse coder or an optical scale, receives or inputs from generator 121 and outputs a signal to control circuit 118. While these elements are required for control of each of the machine axes, only those elements used for one axis are mentioned herein. An I/O circuit 123 also connects to the bus 126 for transferring a digital signal to and from an external device, and a manual pulse generator 124 is connected into the system for moving each axis digitally. An interface circuit 125 connects to bus 126 for transferring a signal to and from the external device. An external storage device 130, which may be a hard disk unit, is coupled with the interface 125 via a communication line 131. The external storage device is not limited to the hard disk unit but may be a floppy disk unit or a card reader unit which transfers data to and from an IC card. In this configuration, a plurality of machining programs are stored in the external storage device 130, the sequence of executing the machining programs and the number of execution times are set and stored in-the non-volatile memory 114 as scheduling data 114a, and workpieces are machined according to the scheduling data 114a to allow the job shop type production of complicated workpieces. FIG. 17 provides an example of a machining program file directory screen, wherein 140 indicates a file directory screen, 141 an indication denoting the file directory screen, 142 a file number section, 143 a file name section, and 144 represents file tape lengths. By setting a cursor on the screen to the file number 0000 and pressing a "SELECT" key 145, the screen progresses to a scheduling data screen. FIG. 18 gives an example of the scheduling data screen, wherein 150 indicates a schedule data screen, 151 an indication denoting the schedule data screen, 152 a run sequence section, and 153 a run program file section. 154 indicates a program file run count section, meaning the number of workpieces to be machined. 155 indicates a currently run program file count section, meaning the number of workpieces already machined. In a preferred order for programming the machining of several work pieces, the scheduling data screen 150 is first selected and the data of the run sequence 152, the program file 153 and the run count 154 are entered to complete the scheduling data. This scheduling data is then stored into the non-volatile memory 114 as the scheduling data 114a. By later selecting and executing this scheduling data 114a, a plurality of workpieces can be machined on a predetermined number basis. Multiple pieces of such scheduling data may be created and registered in the non-volatile memory 114. The conventional numerical control unit configured as described above only executes the scheduling data in sequence and cannot achieve a scheduled run meeting complicated conditions in a practical machining environment, as described in several examples given below. In one example, an alarm condition such as tool wear, machine-generated heat, consumable part wear or a machining program error may occur during actual, long-time unattended machining. Without a schedule changing function at the occurrence of alarm, the conventional numerical control unit stops its operation on occurrence of the alarm. Hence, if a schedule command is given to machine 100 workpieces during an unattended operation at night, the occurrence of alarm at the 10th workpiece leaves the remaining 90 workpieces unmachined until the morning, when the operators return to their assigned stations. In another example, machining accuracy tends to deteriorate as the number of workpieces machined increases. This is due to the thermal deformation of the machine, tool wear, etc. in actual long-period unmanned operation. To prevent this, it is desired to add a compensation factor to the original machining data by executing a tool measurement program every time several workpieces have been machined. Since the schedule run function of the known numerical control unit does not allow the measurement program to be registered independently of the machining program, the measurement program is registered together with the machining program. Therefore, the measurement program is called every time only one workpiece has been machined, increasing wasteful non-machining time and reducing productivity. In a further example, assume that two types of parts, part A and part B, are machined by a machine tool which performs a schedule run. Also assume that two pieces of part B will be assembled to one piece of part A in a postprocess. In such a case, it is desired to machine one piece of part A and two pieces of part B as a set in order to decrease an intermediate stock between the machining process of the machine tool and the assembling postprocess. When one piece of part A and two pieces of part B cannot be mounted on one workpiece, a long list of schedule must be registered, e.g. one piece of part A and two pieces of part B, one piece of part A and two pieces of part B, . . . , in the schedule run function of the conventional numerical control unit. However, such registration is not practical because the number of schedule elements that can be registered is limited. Hence, the parts are registered in blocks, e.g. 100 pieces of part A and 200 pieces of part B. This procedure produces an intermediate stock of 100 pieces of part A between the machining process of the machine tool and the assembling postprocess. Such a large intermediate stock requirement reduces the production efficiency of the whole manufacturing line. In another example, when considering how to improve the productivity of a plant, which is not automatic in setup and chip removal work and requires an operator for machining, the warm-up time of a machine is non-production time. It is desired to have finished such warm-up in early morning, before the operator arrives at work. In addition, for example, long-time continuous machining tends to deteriorate machining accuracy due to heat generation. To prevent this, it is desired to provide predetermined machine cooling time between schedules. However, since the schedule run function of the known numerical control unit cannot provide time-of-day information for the schedule, a desirable schedule run cannot be achieved. Finally, the schedule data registration/display function known in the art is an independent function. Therefore, for example, if it is desired to correct the tool numbers of the following machining programs because tool breakage has taken place during the run of a machining program registered to the schedule, a memorandum of all the machining program numbers that follow must be made, a transition made to an edit screen from the keyboard, then the machining program numbers entered, and the machining programs corrected in the sequence written in the memorandum. Hence, a corrected machining program number error is apt to occur. SUMMARY OF THE INVENTION The present invention will overcome the aforementioned disadvantages in the conventional numerical control unit. It is an object of the present invention to provide a numerical control unit which will not stop a schedule run if an alarm occurs during the run but will change the schedule in response to the alarm to continue the schedule run. It is a further object of the present invention to provide a numerical control unit which has a schedule run function allowing a measurement program to be scheduled in addition to the scheduling of workpiece machining to ensure that the schedule run may be made for optimum measurement program execution. It is a further object of the present invention to provide a numerical control unit which will allow the machining of a plurality of workpieces to be scheduled as one set. It is a further object of the present invention to provide a numerical control unit which will allow time-of-day information to be included in the schedule and a run to be performed at desired time of day. It is a further object of the present invention to provide a numerical control unit which will allow a direct transition to be made from a schedule data display screen to a machining program edit screen, without needing to take a memorandum. The numerical control unit concerned with the first, second, third, fourth, fifth, sixth and tenth embodiments is designed to achieve the first goal and includes schedule skipping means for causing a schedule skip at the occurrence of an alarm. The numerical control unit concerned with the seventh embodiment is designed to achieve the second goal and includes a memory for storing a measurement schedule. The numerical control unit concerned with the eighth and ninth embodiments is designed to achieve the third goal and includes a memory allowing at least two or more schedule elements to be registered as one group. The numerical control unit concerned with the eleventh and twelfth embodiments is designed to achieve the fourth goal and includes a memory for storing schedules and run start time of day corresponding to the schedule, a clock and time-of-day reading means. The numerical control unit concerned with the thirteenth embodiment is designed to achieve the fifth goal and includes machining schedule specifying means, schedule display-to-edit transition means and edit-to-schedule display transition means. The schedule skipping means in the first embodiment stops current machining when an alarm occurs, skips to an executable schedule, and resumes the schedule run. The schedule skipping means in the second embodiment stops current machining when an alarm occurs, skips to a next machining program, and resumes the schedule run. The schedule skipping means in the third embodiment stops current machining when an alarm occurs, skips to a next tool change command, and resumes the schedule run. The schedule skipping means in the fourth embodiment stops current machining when an alarm occurs, skips to a next workpiece change command, and resumes the schedule run. The schedule skipping means in the fifth embodiment stops current machining when an alarm occurs, skips to a next pallet change command, and resumes the schedule run. Alarm type determining means in the sixth embodiment identifies an alarm type when an alarm occurs and activates the schedule skipping means associated with the identified alarm type. The schedule skipping means that is activated will stop the current machining, skip .to an executable schedule, and resume the schedule run. The schedule skipping means in the tenth embodiment stops current machining when an alarm occurs, skips to a specified layer, and resumes the schedule run. The memory in the seventh embodiment stores a measurement schedule corresponding to a machining schedule. In the schedule run, not only the machining schedule but the measurement schedule as well is referenced to execute a measurement cycle. The memory in the eighth embodiment allows a plurality of schedule elements to be stored as one group of schedule data. In the schedule run, the schedule elements belonging to the group are executed in sequence. The memory in the ninth embodiment allows at least one or more groups of schedule elements to be stored as one higher-level group of schedule data. In the schedule run, the lowest-level schedule elements belonging to the group are executed in sequence. The memory in the eleventh embodiment stores a schedule and run start time of day corresponding to that schedule. The clock counts the current time of day. A time of day reading means reads the current time of day from the clock, compares it with the run start time of day, and starts a schedule run when the current time of day has passed the run start time of day. The memory in the twelfth embodiment stores a schedule and run start time of day corresponding to that schedule. The run start time of day is stored as a time increment referenced from a particular time of day, for example, the preceding machining end time of day. The clock counts the current time of day. The time-of-day reading means reads the current time of day from the clock, compares it with the run start time of day, and starts a schedule run when the current time of day has passed the run start time of day. The machining schedule specifying means in the thirteenth embodiment is capable of reading the name of a machining schedule block at the cursor. The schedule display-to-edit transition means calls a machining program corresponding to the name of the machining schedule block and activates the editing means. The edit-to-schedule display transition means searches for a schedule block wherein the machining program called on the edit screen has been registered and activates the machining schedule displaying means. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a hardware block diagram of a numerical control unit according to a first embodiment of the present invention. FIG. 2 is a table diagram showing a single-block structure of machining schedule data and that of measurement schedule data according to an embodiment of the present invention. FIG. 3 is a table diagram illustrating registration examples of the machining schedule data and the measurement schedule data according to an embodiment of the present invention, in connection with blocks. FIGS. 4(a) and 4(b) show main function and single-schedule block run processing flowcharts, respectively, according to an embodiment of the present invention. FIGS. 5(a), 5(b) and 5(c) show skip completion check, run start time of day wait, and machining program skip search processing flowcharts, respectively, according to an embodiment of the present invention. FIGS. 6(a) and 6(b) illustrate skip condition flag set and measurement block call processing flowcharts, respectively, according to an embodiment of the present invention. FIG. 7 shows a main schedule run setting display screen displayed on a CRT/MDI unit according to an embodiment of the present invention. FIG. 8 illustrates a "PART AB" schedule run setting display screen displayed on a CRT/MDI unit according to an embodiment of the present invention. FIG. 9 illustrates a "PART B" schedule run setting display screen displayed on the CRT/MDI unit according to an embodiment of the present invention. FIG. 10 shows a setting display screen, wherein "PART B MEASUREMENT" has been selected for the "PART AB" schedule run, displayed on the CRT/MDI unit according to an embodiment of the present invention. FIG. 11 shows a measurement schedule setting display screen displayed on the CRT/MDI unit according to an embodiment of the present invention. FIG. 12 illustrates an "O103(DRILLING)" edit screen displayed on the CRT/MDI unit according to an embodiment of the present invention. FIG. 13 is a specified block change processing flowchart according to an embodiment of the present invention. FIG. 14 is an open processing flowchart according to an embodiment of the present invention. FIG. 15 is a close processing flowchart according to an embodiment of the present invention. FIG. 16 is a hardware configuration diagram of a numerical control unit known in the art. FIG. 17 provides an example of a machining program file directory screen of the known numerical control unit. FIG. 18 gives an example of a scheduling data screen of the prior art numerical control unit. DESCRIPTION OF THE PREFERRED EMBODIMENT A first embodiment of the present invention will now be described in reference to the appended drawings. In FIG. 1, a CPU 1 of a microprocessor is incorporated in a numerical control unit for executing a command in accordance with a control program written in a ROM 4, reading time of day from a clock LSI 8, transferring data to and from an SRAM 2, carrying out machine control by entering signals of a CRT/MDI unit 7 and a machine operation board 9, conducting machining locus control by sending a command to a servo control unit 5, transmitting and displaying data on the CRT/MDI unit 7, generating a voice by sending a command to a voice output device 10, transmitting various data by sending data to a communication unit 11, and receiving from a communication control unit data sent through a communication line and a modem. All of these operations are conducted via a data bus 14 that connects the CPU to other units. Specifically, a random access memory 2 for storing machining command programs, machining schedules, measurement schedules, run start time of day, etc, is backed up by a battery 3 so that the memory 2 allows the data to be stored while the power of the numerical control unit is off. The servo control unit 5 is operative for driving a motor 6, in accordance with a command from the CPU 1, which effects the operation of a machine. The CRT/MDI unit 7 is employed in the interactive control and monitoring of the numerical control unit by an operator and comprises a display for visually providing relevant information. A voice output device 10 is used for similar purposes and generates a voice or other audible message according to commands from the CPU 1. A machine operation board is operative to generate machine operation signals, such as automatic start and reset, according to the activity of the operator. The clock LSI 8 provides the current time of day and allows it to be read. The communication control unit 11 is used for transmitting data from the CPU 1 to a communication line 12 and a modem 13 in accordance with a communication protocol and transferring to the CPU 1 data sent through the communication line and the modem. Specifically, the modem 13 is connected between a telephone line and the communication control unit 11 for bidirectional communication protocol conversion, allowing data to be transferred via the telephone line to a host computer (not shown) or the like. FIG. 2 is a table illustrating the structure of one block 21 of machining schedule data and one block 22 of measurement schedule data in the first embodiment of the present invention. These blocks of data are stored in the SRAM 2. In the structure of the one block of machining schedule data: "name" indicates the name of a schedule element, wherein a part name or a program number is set. In this example, a part name "Part A" has been set; "numb" indicates the number of machining operations to be repeated. In this example, 2 has been set, representing that two pieces of part A will be machined in this schedule; "cnumb" indicates the number of machining operations already repeated. In the example, it is 1, indicating that one piece of part A has already been machined; "time" indicates time information and "t type" a type of time information If "t type" is "ABS," "time" is the absolute time of day, and if it is "INC," "time" is incremental time from a preceding schedule element. "t type" of "ABS" in this example indicates that this schedule is started at 18 o'clock; "skip" indicates a skip destination at the occurrence of alarm. "0" does not cause a skip. "NEXT" causes a skip to a next machining program, "TOOL" to a next tool change command, "WORK" to a next workpiece change command, "PALLET" to a next pallet change command, "CONDITION" to a skip destination specified by a condition, and "CLASS" to a program scheduled to be run most recently in a specified layer. "NEXT" has been set in this example; "class" specifies a layer of a skip destination when the "skip" element is specified as "CLASS". A "class" of 0 indicates an identical layer, 1 one layer up, and -1 one layer down. Since "skip" is not specified to be "CLASS" in the example, "class" is insignificant. "sub" indicates a pointer denoting a block of schedule one layer down. "sub" is 0 when there is no lower layer. The example indicates that a block "sdata10" is in a lower layer. "mes" indicates a pointer representing a block of measurement schedule. "mes" is 0 when there is no block of measurement schedule. The example shows that there is a block of measurement schedule named "mdata1." "next" indicates a pointer denoting a block of schedule to be run next. "next" is 0 when there is no schedule to be run next (i.e. a final block). The example indicates that a block "sdata" 2 will be run next. The structure of one block of measurement schedule data will now be described. "name" indicates a name of a measurement program, wherein "O9000" has been set in the example. "numb" indicates how many times a parent block of the measurement schedule block will be run before the measurement program is run once. 5 has been set in this example, indicating that 09000 is executed once every time 5 pieces of part A are machined. "cnumb" indicates a cyclic counter which counts up each time the parent block of the measurement schedule block is run and is cleared to zero every time the number set to "numb" is reached or exceeded. 1 has been set in the example, indicating that 1 piece of part A has been machined after the preceding measurement. FIG. 3 illustrates the registered examples of machining schedule data and measurement schedule data in the first embodiment of the present invention, organized in connection with the performance of their constituent blocks. In FIG. 3, "sdata1" indicates a block that is run first. "sdata1" consists of two blocks, "sdata10" and "sdata11," and further "sdata11" is made up of two blocks, "sdata110" and "sdata111." Accordingly, "sdata1" is terminated after the blocks "sdata 10," "sdata110" and "sdata111" are run several times. "mdata10" is a measurement schedule block connected to "sdata1" and is provided with a counter which counts up every time "sdata1" is executed. A measurement program is run once every set number of times. "sdata2" indicates a machining schedule block connected to "sdata1" and is run after "sdata1" is terminated. Similarly, "sdata2" is connected to "sdata3" and linked up to final "sdatan." As seen in the illustrated example, there are three classes of blocks and the various blocks are shown to exist in up to three layers. The first layer block is conventionally identified as a "parent" block while the derivative or dependent blocks in lower layers are called "child" blocks. In the illustrated example, sdata1 block 21A is a parent machining block that itself would not be machined but its derivative block sdata10 21B is a child block that is machined while its derivative block sdata11 21C is a child block that is not machined, although it further derivative blocks 21D and 21E at the lowest layer are machined. Operation of the first embodiment will now be described in connection with FIG. 4(a), which is a processing flowchart of a main function for schedule run control. This function is called when the schedule run is started, at step 400. Step 401: First, an address (&sdata1) of a first schedule block (sdata1) is assigned to a pointer local variable (point) indicating the address of the schedule block. Step 402: A "single-schedule block run" subroutine is then called using the "point" as an argument. While tracing the schedule blocks one after another, this subroutine will run all schedule blocks according to the schedule. Step 403: The schedule run is terminated. FIG. 4(b) is a processing flowchart of the single-schedule block run and begins at step 409. To this subroutine, the parent program passes the pointer local variable (point) indicating the address of the schedule block to be run. Step 410: The number of run times is first cleared to zero (cnumb=0). Step 411: A "skip completion check" subroutine is called to check if a schedule skip is complete or not. Step 412: A check is made to see if the schedule skip is being made or not. The skip is being made if a skip flag is on. Since it is not necessary to wait until the run start time of day during a skip, the processing branches to step 414. Step 413: A "wait until run start time of day" subroutine is called and the processing waits until the current time of day passes the run start time of day. Step 414: A check is made to see if there is a child block or not. There is a child block unless "sub" of the machining schedule block is 0 . If there is no child block, the processing branches to step 418 and performs a machining program run. If there is a child block, the processing progresses to step 415 and performs a child block run. Step 415: Since the child block is to be run, a global variable (classno), used to count layers for checking a layer skip, is counted up. Step 416: To run the child block, the address of the child block (point) is read from "sub" and set to the argument of the "single-schedule block run" subroutine. Step 417: The "single-schedule block run" subroutine is called and the child block and all subsequent blocks are run according to the schedule. As described above, the "single-schedule block run" subroutine is a recursive function capable of calling itself, which logically allows the blocks in an infinitely deep layer to be run according to the schedule if there is no limit to the memory size. Step 418: When there is no child block, the processing branches from the step 414. In this case, a program set to the "name" of this block is run. Hence, a "beginning of machining program search" subroutine is called and the beginning of the program set to the "name" is searched for. Step 419: If a skip is being made, the processing advances to step 420 to perform a skip search. Step 420: A "machining program skip search" subroutine is called and a search is made within the machining program found by searching for the beginning of the machining program. For example, a tool change command or a pallet change command is searched for and the skip flag is switched off. Step 421: A check is made to see if the skip is being made or not. If the skip is being made, the processing branches to step 428 since it is not necessary to run. Step 422: If a skip is not being made, a "machining program run" subroutine is called and a run is made up to the end of the machining program or until an alarm stop occurs. Step 423: A check is made to see if the run has been stopped by alarm or not. If the run has been terminated without fault, the processing branches to step 427 to run a next schedule, and the current time of day is read from the clock and assigned to a global variable (timer) for storing the run end time of day. The processing then branches to step 428. Step 424: When the run has been stopped by alarm, a "skip condition flag set" subroutine is called to set a global variable skip mode indicating a skip type and the skip flag. Step 425: To resume the schedule, the alarm is reset. Step 426: The current time of day is read from the clock and assigned to the global variable (timer) for storing the run end time of day. The processing then returns to the step 419, makes the machining program skip search, and resumes the run when the skip has been found. If it has not been found, the processing branches to step 428 during the skip and moves on to the next block. Step 428: The number of run times (cnumb) of this schedule block is counted up. Step 429: A check is made to see if the skip is being made or not. If the skip is being made, the processing branches to step 431 because measurement need not be conducted. Step 430: A "measurement block call" subroutine is called to run the measurement block. Step 431: A comparison is made between the specified number of runs to be made (numb) and the number of runs actually made (cnumb) for this schedule block to check whether the run has been made the specified number of times. If the run has not yet been performed the specified number of times, the processing branches to the step 411 to run this block again. Step 432: When the run has been made the specified number of times, a check is made to see if a next block exists or not. When "next" is 0, there is no next block. When there is a next block, the address of the next block is read from "next" and assigned to the pointer local variable (point) indicating the block address (at step 433), and the processing branches to the step 410, thereby running the next block. Step 434: Since the processing returns to the parent block when the next block does not exist, the global variable (classno) employed to count layers for checking the layer skip is counted down. Step 435: The processing returns to the function of the parent program. FIG. 5(a) is a skip completion ,check processing flowchart that begins at START step 500. Step 501: Since the skip is complete if the skip is not being made, the processing branches to step 507 and returns to the parent program. Step 502: If the skip mode is "NEXT," reaching the beginning of the single-schedule block run should cause the next program to be run. Hence, the skip flag is switched off at step 503 to complete the skip. Step 504: If the skip mode is "CLASS" and (step 505) "classno" is 0, the layer skip is complete. The skip flag is therefore switched off at step 506 to complete the skip. Step 507: The processing returns to the parent program. FIG. 5(b) is a "wait until run start time of day" processing flowchart that begins at START step 510. Step 511: A check is made to see if the time of day has been set or not. If "time" of the schedule block is not 0, the time of day has been set. Since it is not necessary to wait until the start time of day if the time of day has not been set, the processing branches to step 517 and returns to the parent program. Step 512: The "time" of the schedule block is assigned to a local variable (start-time) indicating the run start time of day. Step 513: A check is made to see if the time of day set value is an increment or an absolute value. The set value is an increment if "t-type" of the schedule block is "INC." If it is an increment, run end time of day is added to the "start-time" at step 514 to find the "start-time" on an absolute time of day basis. Since the "start-time" is already the absolute time of day if the set value is not an increment, the processing branches to step 515. Step 515: The current time of day is read from the clock. Step 516: The current time of day is compared with the "start-time" to check whether it is past the run start time of day. If the run start time of day is not yet reached, the processing branches to the step 515 and waits until the run start time of day is reached. When it is past the run start time of day, the processing advances to step 517 and returns to the parent program. FIG. 5(c) is a machining program skip search processing flowchart that begins with START step 520. Step 521: A check is made to see if the skip mode is "TOOL" or not. If it is not "TOOL," the processing branches to step 525. Step 522: The machining program currently being executed or having been found by searching its beginning is searched from the beginning to the end for a tool change command. Step 523: If a tool change command has not been found until the end, the processing branches to step 525 without any further execution to search the next machining program for the command. Step 524: Since the tool change command has been found, the skip flag is switched off to complete the skip. Accordingly, the next machining program is run, beginning with the tool change command found. Step 525: A check is made to see if the skip mode is "WORK" or not. If it is not "WORK," the processing branches to step 529. Step 526: The machining program currently being executed or having been found by searching its beginning is searched from the beginning to the end for a workpiece change command. Step 527: If a workpiece change command has not been found until the end, the processing branches to step 529 without any further execution to search the next machining program for the command. Step 528: Since the workpiece change command has been found, the skip flag is switched off to complete the skip. Accordingly, the next machining program is run, starting with the workpiece change command found. Step 529: A check is made to see if the skip mode is "PALLET" or not. If it is not "PALLET," the processing branches to step 533. Step 530: The machining program currently being executed or having been found by searching its beginning is searched from the beginning to the end for a pallet change command. Step 531: If a pallet change command has not been found until the end, the processing branches to step 533 without any further execution to search the next machining program for the command. Step 532: Since the pallet change command has been found, the skip flag is switched off to complete the skip. Accordingly, the next machining program is run, beginning with the pallet change command found. Step 533: The processing returns to the parent program. FIG. 6(a) is a skip condition flag set processing flowchart, that begins with START step 600. Step 601: The "skip" of the schedule block is checked. If the "skip" is not "NEXT," the processing branches to step 603. Step 602: If the "skip" is "NEXT," the skip flag is switched on to set "NEXT" to the skip mode. Step 603: The "skip" of the schedule block is checked. If the "skip" is not "TOOL," the processing branches to step 605. Step 604: If the "skip" is "TOOL," the skip flag is switched on to set "TOOL" to the skip mode. Step 605: The "skip" of the schedule block is checked. If the "skip" is not "WORK," the processing branches to step 607. Step 606: If the "skip" is "WORK," the skip flag is switched on to set "WORK" to the skip mode. Step 607: The "skip" of the schedule block is checked. If the "skip" is not "PALLET," the processing branches to step 609. Step 608: If the "skip" is "PALLET," the skip flag is switched on to set "PALLET" to the skip mode. Step 609: The "skip" of the schedule block is checked. If the "skip" is not "CLASS," the processing branches to step 611. Step 610: If the "skip" is "CLASS," the skip flag is switched on to set "CLASS" to the skip mode. The "class" of the schedule block is also read and set to "classno." Step 611: The "skip" of the schedule block is checked. If the "skip" is not "CONDITION," the processing branches to step 620. If the "skip" is "CONDITION," the processing branches to the step 612. Step 612: The alarm is checked. If the alarm is not a "program error," the processing branches to step 614. Step 613: Since the alarm is a "program error," the processing causes a skip to the next machining program. The skip flag is switched on and "NEXT" is set to the skip mode. Step 614: The alarm is checked. If the alarm is not a "no-tool error," the processing branches to step 616. Step 615: Since the alarm is a "no-tool error," it is desired to abandon the machining with this tool and resume the machining with a next tool. Hence, the processing causes a skip to the next tool change command. The skip flag is switched on and "TOOL" is set to the skip mode. Step 616: The alarm is checked. If the alarm is not a "tool breakage error," the processing branches to step 618. Step 617: Since the alarm is a "tool breakage error," this workpiece probably was damaged when the tool was broken. Therefore, it is desired to abandon the machining of this workpiece and resume the machining for a next workpiece. Hence, the processing causes a skip to the next workpiece change command. The skip flag is switched on and "WORK" is set to the skip mode. Step 618: The alarm is checked. If the alarm is not a "pallet loading error," the processing branches to step 620. Step 619: Since the alarm is a "pallet loading error," it seems that the pallet cannot be loaded to the machine properly or use of this pallet may be impossible. Therefore, it is desired to abandon the machining using this pallet and resume the machining employing a next pallet. Hence, the processing causes a skip to the next pallet change command. The skip flag is switched on and "PALLET" is set to the skip mode. Step 620: The processing returns to the parent program. FIG. 6(b) is a measurement block call processing flowchart which begins with START step 630. Step 631: A check is made to see if a measurement block is present or absent. The measurement block exists if "mes" of the schedule block is not 0. If there is no measurement block, the processing branches to step 637 and returns to the parent program. Step 632: Since there is a measurement block, the number of measurement block call times is counted up. "cnumb" of the measurement block indicates the number of call times. Step 633: A check is made to see if measurement is made or not. A comparison is made between "cnumb" and "numb" of the measurement block. The measurement is made if "cnumb" is equal to or greater than "numb." If the measurement is not performed, the processing branches to step 637 and returns to the parent program. Step 634: Since the measurement is carried out, the number of measurement block call times "cnumb" is cleared to zero. Step 635: To run the measurement program, the beginning of the measurement program is searched for by using the measurement program name (name) set to the measurement block as an argument. Step 636: The measurement program is run. Step 637: The processing returns to the parent program. FIG. 7 shows a schedule run setting/display screen displayed on the CRT/MDI unit 7, wherein "MACHINING NAME" indicates a setting/display section of names on a schedule basis. In this example, two schedules of "PART AB" and "PART C" have been registered. "QTY" indicates the number of schedule repetitions, and "NO. MACHINED" the number of run repetitions from when the run of "PART AB" is started finally. "START TIME" indicates reserved run start time of day or run interval time. "SKIP TYPE" indicates a type of a schedule skip caused when alarm occurs. "MEASUREMENT NAME" indicates the name of a measurement schedule block called for in a schedule run. Concerning "PART AB", 2 in the "QTY" section indicates that machining was scheduled to be repeated twice and 2 in the "NO. MACHINED" means that the machining has been repeated twice. 18:00:00 in the "START TIME" section tells that the machining was specified to start at 18 o'clock sharp. Since there is no setting in the "SKIP TYPE" section, a skip was not designated at the occurrence of alarm. Because nothing has been set in "MEASUREMENT NAME," no measurement is made after the run of "PART AB." In regards to "PART C," 100 in the "QTY" section indicates that 100 pieces have been set for machining and 58 in "NO. MACHINED" shows that 58 pieces have been machined. 00:00:40INC in the "START TIME" section means that the machining is done at intervals of 40 seconds. No setting in "SKIP TYPE" tells that an alarm-time skip is not specified. "PART C MEASUREMENT" in "MEASUREMENT NAME" denotes that the measurement schedule block "PART C MEASUREMENT" is called every time the machining of "PART C" is over. The run status of each schedule block is displayed at the left end of the screen. In this example, the run of "PART AB" is complete and that of "PART C" is being made. A horizontal line under "PART AB" is a cursor which is moved on the screen by pressing cursor keys (such as →, ←, ↑ and ↓) to select any of the display items. "PART AB" has been selected in the example. By pressing a key corresponding to "OPEN" in this state, the details of "PART AB" can be displayed. FIG. 8 shows a display screen of the detailed schedule of "PART AB." In the example, "PART AB" consists of two schedule blocks, "PART A" and "PART B." Pressing a key corresponding to "CLOSE" on this screen returns to a higher-level schedule screen shown in FIG. 7. In the example in FIG. 8, the cursor is located under "PART B," indicating that "PART B" is being selected. By pressing the key associated with "OPEN" in this state, the details of "PART B" can be displayed. FIG. 9 provides the detailed schedule of "PART B." Pressing the key associated with "CLOSE" on this screen returns to the screen in FIG. 8. According to the example in FIG. 9, the schedule block "PART B" comprises six blocks; "O100(MILLING)," "O101(ROUGHING)," "O102(STARTING HOLE)," "O103(DRILLING)," "O104(SPOT FACING)" and "O105(FINISHING)." The "SKIP TYPE" for "O100(MILLING)" is "CLASS+2" which causes a skip two classes up ("PART AB" or "PART C") when an alarm occurs. The "SKIP TYPE" for "O100(MILLING)" is "TOOL" which causes a skip to the next tool change command at the occurrence of an alarm. The "SKIP TYPE" for "O102(STARTING HOLE)" and "O103(DRILLING)" is "CONDITION" which causes a skip according to the alarm type at the occurrence of an alarm. The "SKIP TYPE" for "O104(SPOT FACING)" is "NEXT" which causes a skip to the next program ("O105(FINISHING)") at the occurrence of an alarm. The "SKIP TYPE" for "O105(FINISHING)" is "WORK" which causes a skip to the next workpiece change command at the occurrence of an alarm. Like FIG. 8, FIG. 10 gives the details of the schedule block "PART AB," wherein the cursor is located under "PART B MEASUREMENT" indicating that "PART B MEASUREMENT" has been selected. By pressing the key corresponding to "OPEN" in this state, the details of "PART B MEASUREMENT" can be displayed. FIG. 11 displays the details of "PART B MEASUREMENT" along with those of the other measurement schedule blocks. In this example, four measurement blocks, "PART A MEASUREMENT," "PART B MEASUREMENT," "PART C MEASUREMENT" and "HOLE DEPTH MEASUREMENT" are being displayed. "PROGRAM NO." denotes a measurement program number. In the example, the program number for "PART B MEASUREMENT" is "o9001." "MEASUREMENT FREQUENCY(1/SETTING)" indicates how many times the measurement block is called before the measurement program is executed once. In the example, "PART B MEASUREMENT" is made once every time the measurement block is called 100 times. "CALL COUNT" indicates how many times the measurement block has been called after the previous measurement was made. In the example, the measurement block has been called 28 times after "PART B MEASUREMENT" was made. When the measurement block is called 72 more times, measurement is made and "CALL COUNT" is cleared to zero. A run status is indicated on the left end. In the example, "PART C MEASUREMENT" is being made. Pressing the key corresponding to "CLOSE" on this screen returns to the display of the schedule block from which the selected measurement block has been called. Since "PART B MEASUREMENT" is selected in the example, the display returns to the screen in FIG. 10. In FIG. 9, the cursor is under "O103(DRILLING)." By pressing the key corresponding to "OPEN" in this state, the details of "O103(DRILLING)" are displayed. Since "O103(DRILLING)" is the lowest-level schedule block, a program as shown in FIG. 12 is displayed. FIG. 12 illustrates the details of "O0103(DRILLING)." Pressing a key associated with "CHECK" on this screen allows the plotting of an "O103(DRILLING)" program to be checked. Pressing a key corresponding to "READ" allows the machining program to be entered from an external input device. Pressing a key corresponding to "PRINT" allows the "O103(DRILLING)" program to be printed out on an external printer. Pressing a key associated with "EDIT" allows the "O103(DRILLING)" program to be edited. Pressing the key corresponding to "CLOSE" returns to the screen in FIG. 9. Processing will now be described. FIG. 13 is a flowchart of "specified block change" processing called when an up cursor key (↑) or a down cursor key (↓) is pressed on the schedule block display screen, beginning with START step 1300. Step 1301: A check is made to see if the key pressed is the up cursor key or not. If it is the up cursor key, the processing branches to step 1304 and moves the specified block one position backward. Step 1302: A check is made to see if there is a next block or not. There is a next block if the "next" of this schedule block is not 0. When there is no next block, the processing branches to step 1307 since there is nothing to be done. Step 1303: The address "next" of the next block is assigned to a pointer global variable "xpoint" indicating the address of the specified block, thereby using the next block as the specified block. The processing then returns to the parent program at step 1307. Step 1304: Since the up cursor key has been pressed, it is desired to employ a block preceding the current specified block as the specified block. Hence, the preceding block is searched for. A block of which "next" matches the current "xpoint" is the preceding block. Step 1305: If the preceding block does not exist, the processing branches to step 1307 because there is nothing to be done. Step 1306: The address of the preceding block is assigned to "xpoint", thereby employing the preceding block as the specified block. Step 1307: The processing returns to the parent program. FIG. 14 is a flowchart of "open" processing called when the key corresponding to "OPEN" is pressed on the schedule block display screen. Step 1401: A check is made to see if there is a child block in the specified block. The child block exists if "sub" of the specified block is not 0. If there is no child block, the processing branches to step 1404 and transits to an edit screen. Step 1402: Since there is a child block, "sub" is assigned to the pointer global variable "xpoint" indicating the address of the specified block, thereby using the child block as the specified block. Step 1403: The schedule block is displayed. The process then returns to the parent block at step 1406. Step 1404: Since there is no child block, the program having the program name (name) of the specified block is searched for to move to the edit screen. Step 1405: The edit screen is displayed. Step 1406: The processing returns to the parent program. FIG. 15 is a flowchart of "close" processing called when the key corresponding to "CLOSE" is pressed on the edit screen or the schedule block display screen. Step 1501: A check is made to see if the edit screen is being displayed or not. If the screen being displayed is not the edit screen (is the schedule block display screen), the processing branches to step 1504. Step 1502: The schedule block wherein the program being displayed on the edit screen is registered is searched for. The block searched for is the one having the "name" matching the program name on the edit screen. Step 1503: The address of the block found is assigned to the pointer global variable "xpoint" indicating the address of the specified block, thereby using it as the specified block. The processing then progresses to step 1507. Step 1504: A parent data block is searched for since "CLOSE" has been selected on the schedule block display screen. Blocks before the specified block are searched for a block whose "sub" is the address of the first block. This is the parent block. Step 1505: When there is no parent data block, the processing branches to step 1507 since there is nothing to be done. Step 1506: The address of the parent data block is assigned to "xpoint," thereby using the parent data block as the specified block. Step 1507: A block preceding the specified block is searched for. The schedule block of which "next" matches "xpoint" is the preceding block. Step 1508: If the preceding block is absent, it indicates that the specified block is the first block and therefore the processing branches to step 1510 and displays the schedule block. Step 1509: The address of the preceding block is assigned to "xpoint" to employ the preceding block as the specified block. To search for the first block, the processing branches to the step 1507 and repeats the following steps. Step 1510: Schedule blocks are displayed, beginning with the specified schedule block indicated by "xpoint." Step 1511: The processing returns to the parent program. According to the present invention, as described above, the schedule skipping means for skipping a schedule at the occurrence of an alarm allows machining to be continued without stopping a schedule run if an alarm occurs during the run. The memory for storing a measurement schedule corresponding to a machining schedule allows any measurement schedule to be made out, ensuring the implementation of the measurement schedule which will not impair productivity greatly. The memory capable of registering two or more schedule elements as one group allows a complicated schedule, such as the repeated machining of multiple sets of workpiece machining, to be made out easily with a small-capacity memory. The clock and the memory for storing run start time corresponding to a schedule allow run start time of day and run interval time to be set, ensuring ease of control such as an unattended warming-up run and an interval run including machine cooling time. The machining schedule specifying means, the schedule display-to-edit transition means and the edit-to-schedule display transition means allow any of schedule data displayed on a schedule registration display screen to be specified and edited and an edit screen for a machining program to be directly transited to a corresponding schedule display screen to check the schedule status of that program, ensuring ease of operation as well as preventing incorrect program edition from being made by writing and/or entering a wrong program number.

A numerical control (NC) machine tool is controlled by a machining program, which gives the machine tool instructions with respect to the machining of a locus on a workpiece, machining conditions and the like, and responds to a variety of input data which may be stored or registered in a manner that comprises a schedule run, and includes a schedule skip capability. The schedule skipping capability permits portions of the scheduled run to be skipped at the occurrence of an event, such as an alarm, but allows machining to be continued without stopping the schedule run. The scheduled run may skip to a new program, to commands for changing tools, pallets, workpieces and the like, or to conduct a measurement schedule run in association with the machining run. The memory for storing a measurement schedule corresponding to a machining schedule allows any measurement schedule to be utilized without impairing machining productivity greatly. The memory is capable of registering two or more schedule elements as one group, thereby allowing a complicated schedule, such as the repeated machining of multiple sets of workpiece machining, to be made out easily with a small-capacity memory. A clock and the memory for storing run start time corresponding to a schedule allow run start time of day and run interval time to be set for unattended operation. Schedule data may be displayed for schedule specification and editing.

FIELD [0001] The present disclosure relates to a control methodology for a wireless fluid level sensor and more particularly to a wireless oil level sensor for an internal combustion engine. BACKGROUND AND SUMMARY [0002] This section provides background information related to the present disclosure which is not necessarily prior art. [0003] It is important to maintain a proper amount of oil in an engine in order for the engine to be properly lubricated. Typically, engines are equipped with a dipstick that is manually removed from an engine in order to observe the oil level of the oil on the dipstick. Although the oil dipstick is a reliable method of detecting the oil level, it requires that the vehicle operator open the vehicle hood and pull the dipstick out of the engine. Optional engine oil switches exist that notify an operator that the oil level is low. These oil switches have to be wired into the vehicle and fixedly mounted within the oil pan at a level representative of a minimum level at which the user needs to be notified of the low oil condition. Therefore, the typical oil level sensor is only useful for providing a low oil indicator when a low oil condition exists. [0004] The present disclosure provides implementation and a control methodology of a wireless oil level sensor. The control methodology includes mounting a wireless oil pressure sensor to the oil plug of an engine. The oil pressure sensor detects a pressure which can then be used to determine a volume or level of oil above the sensor. The oil level sensor can include an accelerometer sensor that can be excited by the vibration caused by the starting of the engine to “wake up” the sensor. The sensor can take an initial pressure reading at start up and associate the pressure reading with an oil level that can then be transmitted to a vehicle control unit. The sensor can remain idle until the accelerometer sensor no longer detects engine vibrations at which time the sensor is activated to take pressure readings at predetermined time intervals and to transmit an associated oil level to the vehicle central processor until a predetermined time period has expired. The oil sensor then goes into sleep mode in order to maximize battery life. [0005] According to another aspect of the present disclosure, the oil sensor can further be utilized to detect an oil change condition and report the oil change condition to the vehicle control unit so that the oil life monitor can be automatically reset without requiring any input from the vehicle operator. [0006] According to a further aspect of the present disclosure, the oil sensor can be utilized to estimate crankcase pressure during engine operation to help service technicians determine if the crankcase ventilation system or piston rings are operating properly. [0007] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. DRAWINGS [0008] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. [0009] FIG. 1 is a schematic view of a vehicle having an engine with a wireless oil sensor disposed in the oil pan according to the principles of the present disclosure; [0010] FIG. 2 is a schematic view of an engine with the wireless oil sensor disposed in the oil pan according to the principles of the present disclosure; [0011] FIG. 3 is a schematic view of the oil sensor mounted to the oil plug received in the oil pan; and [0012] FIG. 4 is a schematic diagram illustrating the communication between the wireless oil sensor and a vehicle control unit according to the principles of the present disclosure. [0013] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION [0014] Example embodiments will now be described more fully with reference to the accompanying drawings. [0015] Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. [0016] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. [0017] When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. [0018] With reference to FIG. 1 , a vehicle 10 is shown including an engine 12 having an oil pan 14 with an oil sensor 16 disposed in the oil pan. The oil sensor 16 can provide wireless signals to the vehicle central processor unit 18 which can display information to the vehicle operator via a vehicle display unit 20 . FIG. 2 shows a larger more detailed view of the engine 12 oil pan 14 with the oil sensor 16 disposed in the oil pan plug 22 . FIG. 3 shows a larger more detailed view of the oil pan plug 22 disposed in a threaded opening 24 in the bottom of the oil pan 14 and with the oil sensor 16 mounted to the oil pan plug 22 . [0019] FIG. 4 provides a schematic illustration of the components of the wireless oil sensor 16 for communication with the vehicle central processor unit 18 . The wireless oil sensor 16 includes a sensor central processor unit 30 that is in communication with a plurality of sensors that can include a pressure sensor 32 , temperature sensor 34 , an accelerometer sensor 36 , and an attitude sensor 37 . Additional sensors can be utilized. A battery 38 is provided for providing power to the wireless oil sensor 16 and an RF transceiver 40 is provided for providing signals to and transmitting signals from the central processor unit 30 . The RF transceiver 40 is capable of transmitting signals to an RF transceiver 42 of the vehicle central processor unit 18 as well as receiving signals from the RF transceiver 42 or from other programming tools 50 ( FIG. 1 ). [0020] The sensor function begins with the sensor in a sleep mode when the engine is off. When the “Key” is turned “on” or the engine is otherwise caused to turn over, the accelerometer sensor 36 is excited by the vibration of the engine and it causes the oil sensor 16 to switch to an operation/awake mode. The oil sensor 16 then immediately reads the temperature and pressure within the oil pan 14 and can convert those temperature and pressure readings into a corresponding oil level (L) at start-up. It is noted that for purposes of the discussion herein, the oil level L and sensed pressure P are used somewhat interchangeably since the sensed pressure generally corresponds to a certain oil level. Optionally, oil level can be converted to oil mass by assuming a known oil density and correcting for temperature. The sensor readings are required to be taken right away before engine operation causes the oil to be dispersed throughout the lubrication system of the engine so that the level of oil in the oil pan 14 is not representative of the amount of oil that is typically measured when the engine is off. The sensor readings are also required before the oil crankcase atmospheric pressure is affected by the engine operation. During the remaining engine operation cycle, the oil sensor 16 can remain idle. [0021] When the key is turned “off” or the engine is otherwise turned off, the excitation of the accelerometer sensor 36 is stopped. After the oil sensor 16 detects that the engine vibration has stopped via the accelerometer sensor 36 , the oil sensor central processor unit 30 initiates a clock and begins sampling the oil level at predetermined increments for a predetermined period of time. By way of non-limiting example, the predetermined increments can be 10 sec increments and the predetermined period of time can be determined based upon a typical amount of time for a majority of the engine oil to return to the oil pan 14 . This time period can range from 1 minute to several minutes for different engine designs. The oil sensor central processor unit 30 can correct the oil level for temperature and optional volume variations or mass and transmit the oil level/volume for each level read to the radio frequency transceiver 42 of the vehicle central processor unit 18 . After the predetermined time period has expired, the oil sensor 16 returns to sleep mode. [0022] The control method of the wireless oil sensor 16 enables the wireless sensor 16 to act autonomously in its environment. The wireless oil sensor is capable of sensing its own environment and can be selectively energized to measure the fluid level when it is possible for accurate measurement. The battery life of the oil sensor is maximized due to the selective operation. The control methodology of the present disclosure enables the use of a wireless engine oil level sensor and has the potential to replace the current oil level dipstick and low oil switch used in present vehicles. The system can result in cost reduction, improved oil level measurement accuracy, improved customer convenience by allowing accurate oil level information to be displayed on a vehicle display 20 . The attitude sensor 37 can be utilized to adjust the oil level reading for tilt if the vehicle is parked on a hill. Therefore, a false low oil level indication can be avoided. [0023] A further feature of the present disclosure is the ability to use the wireless oil sensor 16 to include an algorithm to recognize the environmental conditions that are unique to an oil change. In general, it is recognized that an oil level changes very slowly throughout the operation of a vehicle whereas an oil change will induce a change in oil level over a very short period of time. The oil sensor 16 is able to recognize an oil change event and communicate to the vehicle central processor unit 18 . In particular, according to one aspect of the present disclosure, the oil sensor 16 can calculate a change in oil level with respect to time (dL/dT) and determine if the value of dL/dT is less than 0 and its absolute value is greater than a threshold value, then an oil change event is identified. In other words, in the event the oil sensor 16 is mounted to the oil plug 22 , removal of the oil plug and oil sensor 16 will result in the oil sensor being activated from sleep mode by the accelerometer being excited due to the rotation and removal of the oil plug 22 . Once the oil plug 22 and oil sensor are removed from the oil pan, the oil sensor 16 will recognize an immediate drop in pressure since the pressure sensor 32 is now exposed to ambient pressure. The drop in pressure can be identified as an oil change event that can be identified to the vehicle central processor unit 18 which can either automatically update the vehicle database of the current oil change event or to prompt the vehicle operator via the display 20 to confirm that an oil change is or has been performed. As an alternative, the attitude sensor 37 can be used to detect that the oil plug was removed to signal that an oil change is being performed. The removal of the oil plug would alter the attitude of the oil plug and allow the vehicle central processor unit to discern that an oil change is being performed. [0024] If the oil sensor 16 is not mounted to the oil plug 22 , but is otherwise mounted within the oil pan 14 , the oil sensor 16 will recognize a rapid decrease in pressure over time (dL/dT) as the oil drains from the oil pan 14 . The rapid decrease in pressure over time can be determined to be representative of an oil change event that can be identified to the vehicle central processor unit 18 which can either automatically update the vehicle database of the current oil change event to reset the oil life monitor or to prompt the vehicle operator via the display 20 to confirm that an oil change is or has been performed, and then, if confirmed, can reset the oil life monitor. [0025] According to an alternative oil change check function, a repetitive knocking on the surface of the oil plug 22 in close proximity to the oil sensor 16 can be recognized by the accelerometer sensor 36 and the oil sensor 16 can transmit to the vehicle central processor unit 18 signaling an oil change event in progress. The repetitive knocking can be representative of a wrench engaging the oil plug 22 or another forced pattern that the oil change technician carries out. A repeated knocking pattern (either via re-installation of the oil plug 22 or a forced pattern carried out by the oil change technician) can then be recognized by the accelerometer 36 and the oil sensor 16 can transmit information to the vehicle central processor unit 18 to signal that the oil change event is complete so that the oil life monitor can be automatically reset, either with or without confirmation of the oil change event with the vehicle operator. The oil change detection feature provides a means by which the oil life monitor on a vehicle can be automatically reset rather than requiring vehicle operator input. [0026] According to a further aspect of the present disclosure, the oil sensor 16 located in the oil pan drain plug 22 can be used to estimate crankcase pressure during various operating conditions of the engine to determine if the ventilation system or piston rings are operating properly. Service technicians currently have to install a separate blow-by measuring device onto the engine to determine if the piston rings are not sealing properly. Service technicians also have no means of measuring the crankcase pressure to determine if the ventilation system is operating correctly. The use of the oil sensor 16 to estimate the pressure during engine operation eliminates the need to install a separate crankcase pressure sensor and/or a blow-by measurement device, which saves labor and diagnosis time. In order to use the oil sensor 16 for detecting engine operating conditions, the technician starts the engine and lets it idle. The technician uses a hand held signal monitoring device 50 ( FIG. 2 ) or vehicle display FIG. 2 to read a pressure output from the oil sensor 16 . By way of non-limiting example, pressure values lower than a normal predetermined value (e.g. −4 kPa) can indicate that the crankcase pressure regulation valve is stuck in an open position and requires service. Pressure values higher than a normal predetermined value (e.g. 3 kPa) indicate that the piston rings are not sealing properly or the pressure regulation valve is stuck closed. Accordingly, the oil pressure sensor in the oil pan can be used by service technicians to diagnose engine problems. [0027] An alternative to the technician activating the sensor using a signal monitoring device, is an “automated mode” that detects crankcase pressure periodically during engine operation and reports to the engine central processor unit 18 . The central processor unit 18 captures the signal and determines if the engine is in the required “standard” condition (e.g., warm idle). If so, the central processor unit 18 checks for pressure values being in the “normal” window. If not, the central processor unit 18 provides a signal to notify the operator of possible maintenance requirements. [0028] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

A control methodology for a wireless oil level sensor includes mounting a wireless oil pressure sensor to the oil plug of an engine. The oil pressure sensor detects a pressure which is used to determine a volume or level of oil in the oil pan. The oil level sensor can include an accelerometer sensor that can be excited by the vibration caused by the starting of the engine to “wake up” the sensor. The sensor can take an initial pressure reading at start up and associate the pressure reading with an oil level that can then be transmitted to a vehicle control unit. The sensor can remain idle until the accelerometer sensor no longer detects engine vibrations. The sensor is activated to take pressure readings at predetermined time intervals and to transmit an associated oil level to the vehicle central processor unit until a predetermined time period has expired.

This application claims the benefit of priority of U.S. Provisional Patent Application 60/745,806, filed 27 Apr. 2006, and is a continuation-in-part of U.S. patent application Ser. No. 10/672,060, filed 29 Sep. 2003. FIELD OF THE INVENTION The present invention relates to baseball bats and more particularly to tubular baseball bats, constructed of a variety of materials, and more particularly to baseball bats designed to improve player performance. More particularly, baseball bats according to the invention have variable radial stiffness along the barrel length resulting in larger sweet spots, improved batting performance as defined by greater hitting distance, a vibration soft feel, and unique sounds upon contact with a ball while meeting existing, new, or changed performance standards established by regulatory bodies. BACKGROUND OF THE INVENTION AND PRIOR ART Baseball and softball bats, hereinafter referred to simply as “baseball bats” or “bats”, are today typically made solely from aluminum alloys, or aluminum alloys in combination with composite materials (hybrid bats), or most recently solely from composite materials (with the exception of solid wooden bats for the Major Leagues). Such bats are tubular (hollow inside) in construction in order to meet the weight requirements of the end user, have a cylindrical handle portion for gripping, a cylindrical barrel portion for hitting, and a tapered mid-section connecting the handle and barrel portions. Traditionally, such bats have generally had a constant radial stiffness along their barrel portion length, measuring the radial stiffness along the barrel wall as independent annular segments of the barrel wall at any location along the barrel wall length. When aluminum alloys initially replaced wooden bats in most bat categories, the original aluminum bats were formed as a single member, that is, they were made in a unitary manner as a single-walled aluminum tube for the handle, taper, and barrel portions. Such bats are often called single-wall aluminum bats and were known to improve performance relative to wooden bats as defined by increased hit distance. More recently (in the mid 1990's), improvements in bat design largely concentrated on further improving bat performance. This was accomplished primarily by thinning the barrel wall of the single wall bat frame, and adding inner or internal, and or outer or external, secondary members extending along the entire barrel length. These members are often referred to respectively as inserts or sleeves; while the main member is often referred to as a body, shell or frame. Such bats are often called double-wall bats or multi-walled bats in the case of more than two walls resulting from two or more secondary members. Such double walled and multi-walled tubular bats generally obtained improved performance in terms of hitting distance by reason of the improved elastic deflection that is characteristic of a multilayer barrel wall. The efficient batting of a ball is maximized by minimizing plastic deformation, both within the bat and within the ball. Ideally, during the collision, the barrel wall of the bat should not deform beyond its elastic limit. Use of a multi-wall two or more member construction along the entire barrel length allows the barrel portion of the bat to elastically deflect or flex more upon ball impact which propels the ball faster and further than prior art single wall bats. The scientific principle governing improved bat performance is bending theory. When a ball impacts a bat it has kinetic energy that must be absorbed by the bat in order to stop the ball. The bat stores most of this energy by flexing. The ball as well deforms. After the ball is stopped, the bat returns the energy it has stored by rebounding and sending the ball back towards where it came from. The more the bat barrel or striking portion deforms upon ball impact without failing (denting or breaking) or experiencing plastic deformation, the lower the energy loss and the greater the energy returned to the ball from the bat as the tubular bat barrel portion impacted returns to its original shape. To allow the bat barrel portion to deform, requires lowering the radial stiffness of the barrel portion. The prior art double walled and multi-walled tubular bats have traditionally accomplished this by thinning the main member of the barrel portion and adding thin secondary member insert(s) and/or sleeve(s) which are not bonded to the main member, but which generally extend throughout the full length of the barrel portion. Such inserts and sleeves are not coupled to the barrel wall portion of the frame, and these two contacting components may slide with respect to each other in the same manner as leafs within a leaf spring. The resultant lowered radial stiffness along the barrel portion length permits the barrel wall to deflect elastically. U.S. Pat. No. 5,415,398 to Eggiman is an example of a multiwalled bat that discloses use of a frame and internal insert of constant thickness running full length of the barrel portion of the bat in a double-wall construction. Other similar bat designs are described in U.S. Pat. No. 5,303,917 to Uke which discloses a two member bat of thermoplastic and composite materials and U.S. Pat. No. 5,364,095 to Easton which discloses a two member bat consisting of an external metal tube and an internal composite sleeve bonded to the inside of the external metal tube and running full length of the barrel portion of the bat. U.S. Pat. No. 6,251,034 discloses a polymer composite second tubular member running throughout the full length of the barrel portion of the bat with the members joined at the ends only of the barrel portion with the balance of the composite member freely movable relative to the primary member. U.S. Pat. Nos. 6,440,017 and 6,612,945 to Anderson also disclose two member bats with an outer sleeve and inner shell of constant thickness running full length of the barrel portion. Other references include U.S. Pat. No. 6,063,828 to Pitzenberger, U.S. Pat. No. 6,461,760 to Higginbotham; U.S. Pat. No. 6,425,836B1 to Mizuno, and U.S. Patent Pub. 2001/0094882 A1 to Clauzin. In all the prior art multi-walled tubular bats cited so far, the bat secondary member, or insert, extends along the entire frame barrel length, have constant diameters and thickness resulting in uniform cross-sectional geometry along the secondary member length. Also, the bat members are not joined, except at their ends, in order to reduce radial stiffness of the barrel portion to improve bat performance. Also, in all cases, the radial stiffness of the barrel portion is uniform or constant full length of the barrel portion of the bats. While the prior art single member, and more particularly, double-walled and multi-walled tubular bats have demonstrated improved performance as claimed, various regulatory bodies have raised safety concerns regarding improved performance bats and thus, some have established maximum performance standards for various categories of baseball bats under their jurisdiction. As a result, manufacturers of baseball bats are required to pass various controlled laboratory tests, such as, bbf (batted ball performance), bbs (batted ball speed), etc. Further, for a given bat category (eg. slowpitch softball), there may be two or more regulatory bodies each of which may establish a different standard. Further, any of the regulatory bodies may change their standard from time to time. Such new or changed or varying regulations are extremely problematic, costly, and disruptive for both manufacturers and players. It is not generally desirable to lower the performance of a bat by simply increasing the thickness of the barrel wall of one or more of the barrel members along its full length. Lowering the performance of the bat by merely increasing the wall thickness can increase weight such that the finished bat weight standard or objective is exceeded. On the other hand, it is desirable to increase the wall thickness only in the sweetspot, or mid region, of the barrel portion of the bat without significantly increasing the weight. Therefore, what is needed is a simple, low cost invention to vary, e.g. decrease, bat performance of tubular bats in a controlled manner, in order to meet lowered or changed bat performance standard requirements without significantly increasing or departing from standard bat weight. Further, in conjunction with causing a decrease in batting performance it would be desirable to improve another bat characteristic such as “sweetspot” size. The sweet spot of a bat is generally the portion of the barrel which, with when struck by the ball, provides maximum batting performance. It is the location on the barrel at which the collision occurs with maximum efficiency and with the transmission of minimum vibration through the handle to the hands of a user. While highly subjective, many players would accept that the sweet spot portion on the bat has a dimension of approximately 2 inches, possibly up to 4 inches, in length and is located generally midway along the barrel portion. It is highly desirable to provide improved bats with a predetermined maximum allowable bat performance and a larger sweetspot region than bats of the prior art. This is one of the primary objectives of the present invention. Further, multi-wall bats of the present invention with inventive secondary members with non-uniform cross-sections along their length provide a vibration free soft feel and produce unique sounds upon contact with a ball. U.S. published patent application No. 2005/0070384 with patent application filed Sep. 29, 2003, by the inventors of the current application, addresses the larger sweetspot region objective by varying radial stiffness along the barrel length by adding a stiffener, or by changing fibre properties along the barrel length, or by thickening the barrel wall generally in the area of the sweetspot. U.S. Pat. No. 6,949,038 issued to Fritzke filed Jan. 21, 2004 also addresses this objective. The Fritzke '038 reference purports to achieve an improved sweet spot characteristic by providing a secondary member, located either inside or outside the barrel of a standard frame, wherein the secondary member has a constant outside diameter with an internal wall whose thickness increases while proceeding from its ends inwardly towards the opposing ends. Generally, this thickening is shown to increase to a maximum around the mid-portion of the length of the secondary member. In one figure, FIG. 12 , this thickness is shown to partially decrease around the mid-portion of the length of the secondary member, providing two laterally placed regions of maximum thickness on either side of the mid-portion. While the present inventor's earlier publication and the Fritzke patent represent different means of achieving an enlarged sweet spot of a baseball bat, the present invention includes other means to achieve the same result plus additional benefits regarding performance, feel and sound. Field testing has repeatedly shown that a “soft” feel upon ball impact and/or a “pleasing” sound are both player perceptions which are often favoured by the player over absolute performance as measured by hit distance. SUMMARY OF THE INVENTION Therefore, in view of the foregoing, what is needed is a tubular baseball bat with a specific distribution of variable radial stiffness along their barrel portions in order to vary bat performance along the barrel hitting portion length, to make the bat feel “soft” when striking a ball, and to produce a pleasing sound upon impact with the ball. To achieve these objectives, the bats of the present invention are stiffened in the barrel area of peak bat performance commonly referred to as the sweetspot. Typically, this is an area approximately 2″ to 4″ in width as compared to barrel portion lengths of 4″ to 16″. This is achieved by the presence of an inventive geometric secondary member, or members, with non-constant outside diameters positioned internally within the bat frame, or by independent numerous annular secondary members located along the inner surface of the barrel portion of an external bat frame, or by inserting or adding to the bat a circumferential stiffener in the region of the sweetspot, or by making the barrel wall thicker in the region of the sweetspot, or by having stiffer material in the region of the sweetspot. Such embodiments also can provide variable bat performance along the barrel length, enlarge the sweetspot size, improve bat performance, have a softer feel upon ball impacts, and produce unique pleasing sounds upon ball impact. In one embodiment of the present invention, the inventive internal secondary members have a variable outside diameter and constant wall thickness and are characterized by variations in the surface profile on one side of the secondary member wall being reflected by a corresponding profile on the other side of the secondary wall that provide at least two or more contact regions with the internal barrel portion of the frame barrel wall that in turn create at least one functional air cavity that is closed at both ends. In one variant of the invention internal secondary members have constant internal diameters. In another embodiment of the present invention, two or more independent annular or ring like, members of generally consistent cross-sectional geometry with variable dimensions and with length less than one-half the barrel portion length are internally located in unbonded contact along the inner wall of the barrel portion of an external bat frame. An additional secondary bat member of length approaching the barrel length may be located internally to the annular secondary members. In another embodiment, a short light weight polymer composite circumferential stiffener of the invention as employed adds only minimal weight to a given bat thus allowing the stiffened bat to continued to be used within the required weight requirements set by the relevant governing body. The stiffener of the present invention can be added to previously constructed tubular bats returned from players for modification to meet a changed regulation allowing such previously manufactured bats to meet a changed standard. Though somewhat heavier, a short metallic stiffener could also be employed. An alternative method of varying stiffness, and thus bat performance, along the barrel portion is to vary thickness along the barrel portion. Another alternative solution of the present invention for all composite bats is accomplished by engineering calculation considering selection of the composite fiber type, the fibre size, the angles of the fibers, and the thickness of the polymer composite stiffener to be employed to precisely lower the bat performance. While tubular bats of the present invention have variable radial stiffness along their barrel portions to achieve a specific predetermined bat maximum bat performance, it is simultaneously possible to achieve a sweetspot which is larger than the sweetspot typically found in tubular bats of the prior art. In the present invention this is accomplished by selectively radially stiffening only the peak performance area (generally the sweetspot area) of the bat to provide a radial stiffness therein which is greater than the radial stiffness of the barrel portion area immediately adjacent on both sides of the sweetspot. The resultant effect can be to approximately double the sweetspot size (that is, the area of the barrel portion which provides maximum bat performance). Further, bats of the present invention with secondary members with a variable outside diameter, with or without thickened end portions have a softer feel upon impact and produce unique impact sounds. The foregoing summarizes the principal features of the invention and some of its optional aspects. The invention may be further understood by the description of the preferred embodiments, in conjunction with the drawings, which follow. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a longitudinal cross-section of a typical prior art single wall tubular bat with a singular frame, or member, construction. FIG. 1A shows a cross-sectional area taken at any location through the barrel portion of the FIG. 1 prior art tubular bat. FIG. 2 shows a longitudinal cross-section of a typical prior art double-wall tubular bat with two separate members, a frame or main member with an internal insert as a secondary member in the barrel area. Both the frame and insert run the full length of the barrel portion and are not joined full length. FIG. 2A shows a cross-sectional area taken at any location through the barrel portion of the FIG. 1 prior art tubular bat. FIG. 3 shows a longitudinal cross-section of a typical prior art double-wall tubular bat with two separate members, a frame or main member with an external sleeve secondary member in the barrel portion. Both the frame and sleeve run the full length of the barrel portion and are not joined full length. FIG. 3A shows a cross-sectional area taken at any location through the barrel portion of the FIG. 3 prior art tubular bat. FIG. 4 shows a longitudinal cross-section of one embodiment of the present invention showing a single wall tubular bat in accordance with the present invention showing an internal stiffener generally confined to the sweetspot area of the barrel portion and joined to the barrel portion. FIG. 4A shows a cross-sectional area of a barrel location not within the sweetspot area. FIG. 4B shows a cross-sectional area within the sweetspot area showing the internal stiffener of the present invention. FIG. 5 shows a longitudinal cross-section of a second embodiment of the present invention showing a single wall tubular bat in accordance with the present invention with an external stiffener generally confined to the sweetspot area of the barrel portion and joined to the barrel portion. FIG. 5A shows a cross-sectional area at a barrel location not within the sweetspot area. FIG. 5B shows a cross-sectional area within the sweetspot area showing an external stiffener of the present invention. FIG. 6 shows a longitudinal cross-section of a third embodiment of the present invention showing a single wall polymer composite tubular bat in accordance with the present invention showing a localized area of the fiber type and/or angle change resulting in increased radial stiffness generally confined to the sweetspot area of the barrel portion. FIG. 6A shows a cross-sectional area at a barrel location not within the sweetspot area. FIG. 6B shows a cross-sectional area within the sweetspot area showing a stiffened area of changed fiber angles and/or type. FIG. 6.1 shows a longitudinal cross section of a single wall polymer composite tubular bat in accordance with the present invention showing the alternative construction incorporating a thickened barrel wall 21 resulting in increased radial stiffness generally confined to the sweetspot area of the barrel portion. FIG. 6.1A shows a cross-sectional area at a barrel location not within the sweetspot area. FIG. 6.1B shows a cross-sectional area within the sweetspot area showing a stiffened area with thicker barrel wall. FIG. 6.2 shows a longitudinal cross-section of an alternative double wall polymer composite bat in accordance with the present invention showing a localized area of the fibre type and/or fibre angle change within the insert resulting in increased radial stiffness generally confined to the sweetspot area of the barrel portion. FIG. 6.2A shows a cross-sectional area at a barrel location not within the sweetspot area. FIG. 6.2B shows a cross-sectional area within the sweetspot area showing a stiffened area of changed fibre angles and/or type. FIG. 6.3 shows a longitudinal cross-section of a double wall polymer composite bat in accordance with the present invention with an alternative construction showing a thickened barrel wall 21 within the insert resulting in increased radial stiffness generally confirmed to the sweetspot areas of the barrel portion. FIG. 6.3A shows a cross-sectional area of a barrel location not within the sweetspot area. FIG. 6.3B shows a cross-sectional area within the sweetspot area showing a stiffened area with thicker barrel wall. FIG. 7 shows a longitudinal cross-section of a fourth embodiment of the present invention showing a double-wall tubular bat with two separate members, a frame or main member with an internal insert as a secondary member full length in the barrel portion, and in accordance with the present invention, showing an internal stiffener generally confined to the sweetspot area of the barrel portion and joined to the barrel portion. FIG. 7A shows a cross-sectional area at a barrel location not within the sweetspot area. FIG. 7B shows a cross-sectional area within the sweetspot area showing the internal stiffener. FIG. 8 shows a longitudinal cross-section of a fifth embodiment of the present invention showing a double-wall tubular bat with two separate members, a frame or main member with an external sleeve as a secondary member full length in the barrel portion, and in accordance with the present invention showing an external stiffener generally confined to the sweetspot area of the barrel portion and joined to the barrel portion. FIG. 8A shows a cross-sectional area at a barrel location not within the sweetspot area. FIG. 8B shows a cross-sectional area within the sweetspot area showing the external stiffener. FIG. 9 shows in graphical form the typical relationship between tubular bat performance and barrel location and sweetspot size. FIG. 10 shows in graphical form a typical relationship between tubular bat performance of a bat of the present invention and barrel location and sweetspot size. FIG. 11A shows a longitudinal cross-section of the barrel portion of a typical prior art single wall tubular bat with a singular frame, or main member. Not shown in FIG. 11A and all following figures is the traditional bat handle portion located at the proximal end of the taper portion. FIG. 11B shows a longitudinal cross-section of the barrel portion of a typical prior art single wall tubular bat with a singular frame, or main member, construction wherein the barrel wall is inwardly thickened generally in the area of the sweetspot. FIG. 11C shows a longitudinal cross-section of the barrel portion of a typical prior art double wall tubular bat with an external frame and a secondary internal member, or insert. FIG. 11D shows a longitudinal cross-section of the barrel portion of a typical prior art double wall tubular bat with an external frame and a secondary internal member, or insert, wherein the insert is inwardly thickened generally in the area of the sweetspot. FIG. 11E shows a longitudinal cross-section of the barrel portion of a typical prior art double wall tubular bat with an external frame and a secondary internal member, or insert, wherein both the frame and the insert are inwardly thickened generally in the area of the sweetspot. FIG. 12A shows a longitudinal cross-section of the barrel portion of one embodiment of the present invention showing a double wall tubular bat with an external frame and a primary secondary member, or insert, located internally within the frame wherein the primary secondary member has an outer diameter which varies along the length of the member, a constant wall thickness, two contact regions with the frame barrel portion inner surface, and one air cavity that is closed at both ends. FIG. 12B shows a variant of the bat of FIG. 12A wherein the primary secondary member has a constant wall thickness, there are two contact regions, and one closed air cavity, wherein the thickness of the air cavity is reduced generally in the area of the barrel mid portion. FIG. 12C shows a variant of the bat of FIG. 12A wherein the primary secondary member has a constant wall thickness, there are three contact regions and two closed air cavities. FIG. 12D shows a variant of the bat of FIG. 12A wherein the primary secondary member has a constant wall thickness and the outer diameter of the primary secondary member oscillates periodically along its length between a maximum and a minimum diameter, creating multiple contact regions and multiple closed air cavities. FIG. 12E shows a variant of the bat of FIG. 12D wherein the period of the oscillation of outside diameter of the primary secondary member increases away from the barrel mid portion. FIG. 12F shows a variant of the bat of FIG. 12A with a primary secondary member and an additional secondary member located internally to the primary secondary member wherein both secondary members have outer diameters which vary along the length of the secondary members, have constant wall thicknesses, two contact regions each, and one closed air cavity each. FIG. 12G shows a variant of the bat of FIG. 12A wherein the primary secondary member has a constant diameter internal surface, a non-constant diameter external surface, a non-constant wall thickness, two contact regions with the internal frame wall, and one air cavity that is closed at both ends. FIG. 12H shows a variant of the bat of FIG. 12G wherein the primary secondary member has two contact regions and one closed air cavity that has a non-uniform cross-section. FIG. 12I shows a variant of the bat of FIG. 12G wherein the primary secondary member has three contact regions and two closed air cavities. FIG. 12J shows a variant of the bat of FIG. 12D wherein the primary secondary member has a constant diameter internal surface. FIG. 12K shows a variant of the bat of FIG. 12E wherein the primary secondary member has a constant diameter internal surface. FIG. 12L shows a variant of the bat of FIG. 12F wherein the primary secondary member has a constant diameter internal surface. FIG. 13A shows a longitudinal cross-section of the barrel portion of a second embodiment of the present invention showing a double wall tubular bat with an external frame, and six independent annular secondary members, or rings, each of length less than one-half the frame barrel portion length and varying thickness, each internally located side by side, with or without spaces between, along the frame barrel portion length against the barrel portion inner surface of the external bat frame. FIG. 13B shows a multi-wall bat variant of the bat of FIG. 13A wherein there are six independent annular secondary members each of length less than one-half the frame barrel portion length, each internally located along the frame inner wall surface, and a tubular additional secondary member with length approaching the frame barrel portion length and located internally to the annular secondary members and in contact with at least one annular secondary member, generally extending co-extensively with the frame barrel portion. FIG. 13C shows a variant of the bat of FIG. 13B wherein there are six independent annular secondary members each of length less than one-half the frame barrel portion length, each internally located along the additional secondary member outer wall surface and internally to the external frame inner wall surface. FIG. 13D shows a variant of the bat of FIG. 13B wherein there are three independent annular secondary members of constant thickness each internally located between and abutting against the external frame inner wall surface and the additional secondary member outer wall surface forming three closed air cavities. FIG. 13E shows a variant of the back of FIG. 13D wherein there are multiple annular secondary members with or without multiple air cavities. FIG. 13F shows a longitudinal cross-section of the barrel portion of another embodiment of the present invention showing a multi-wall tubular bat with an external frame, and two annular secondary members, or rings, each of length less than one-half the frame barrel portion length, wherein each annular secondary member is located between the outer frame and an additional secondary member with length approaching the frame barrel portion length, wherein the wall of the additional secondary member is thickest generally in the frame barrel mid portion providing a contact area between the inner surface of the frame and the outer surface of the additional secondary member. DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to providing tubular baseball bats with variable radial stiffness along the length of the barrel or hitting portion 1 , of the bats. Bats of the present invention can have a larger sweetspot size 19 , have a soft feel with substantially reduced vibrations, and produce unique pleasing sounds upon impact with a baseball or softball. Further, such bats can be produced at reasonably low costs. Unless otherwise indicated, the term stiffness as used in this disclosure is equivalent to the modulus of elasticity and is a measure of the change in length of a material under loading. For a tubular body, such as a baseball bat, stiffness of the material can be measured in the axial direction, parallel to the longitudinal axis of the tube, or the radial or transverse direction perpendicular to the longitudinal axis of the tube. Radial stiffness is a measure of the force required to depress any given a section of the tube in the radial direction. Radial stiffness is a function of modulus of the material, the tube thickness and the tube diameter. Radial stiffness is measured along the barrel wall as independent annular segments of the barrel wall at each measurement location. The prior art bats are shown in FIGS. 1 , 2 , 3 , and 11 . FIGS. 1 and 11A show a single wall tubular bat with main member or frame 16 . FIGS. 2 and 11C show a double wall tubular bat with an insert or primary secondary member 13 , formed separately from the main member 16 , which is fitted into the entire barrel length 1 of the main member 16 . FIG. 3 shows a double wall tubular bat with a sleeve 14 , formed separately from the main member 16 , which is fitted over the entire barrel length 1 of the main member 16 . FIG. 11B shows a single wall tubular bat with the main member 16 being internally thickened in the barrel mid-section. FIGS. 11D and 11E show double wall tubular bats with an internally thickened secondary member 13 and in the case of FIG. 11E also an internally thickened main member 16 . Though not indicated in FIGS. 1 through 8 , and 11 through 14 , bats of the present invention, similarly to bats of the prior art, include a traditional knob at the handle portion end 5 , or proximal end of the bat, and a traditional end cap 21 (not shown in FIGS. 1 through 8 ) at the barrel portion end 4 , the distal end, both of which can be made from a variety of materials. Most adult tubular baseball bats of the prior art have maximum outside barrel portion diameter 2 of either 2.625 inches or 2.75 inches. Depending on the taper portion geometry of the mid-section 8 , and the total length of the bat, the barrel length 1 as defined by length of constant maximum diameter 2 , ranges from 4 to 12 inches. Total barrel wall thickness 6 ranges from 0.100 inches to 0.140 inches for aluminum bats and up to 0.220 inches for all composite bats and is measured at any point along the barrel wall as the outside diameter of the frame or member with the largest outside diameter minus the inside diameter of the member with the smallest outside diameter including any gaps, or spaces, between the two extreme diameters. Most youth baseball bats and softball bats of the prior art have maximum outside barrel portion diameter 2 of 2.25 inches. Depending on the taper portion geometry of the mid-section 8 , the barrel length 1 ranges from 4 to 16 inches. Barrel wall thickness 6 ranges from 0.060 inches to 0.090 inches for aluminum bats and up to 0.220 inches for all composite bats. The bats of the present invention, shown in FIGS. 4 through 8 , and 12 through 14 , have similar dimensions to the foregoing prior art bats shown in FIGS. 1 , 2 , 3 , and 11 . A first embodiment of the present invention FIG. 4 is a single wall tubular baseball bat consisting of a cylindrical handle portion 7 for gripping, a cylindrical tubular barrel portion 9 for striking or hitting, and a tapered portion 8 connecting the handle 7 and barrel 9 portions, with a thin polymer composite stiffener 18 having a stiffener wall located internally within the barrel portion 9 and extending longitudinally in the mid-section, sweetspot area 19 of the barrel length 1 . A polymer composite is a non-homogenous material consisting of continuous fibers embedded in, and wetted by, a polymeric resin matrix whereby the properties of the material are superior to those of its constituent fibers and resin taken separately. Such polymer composites are anistropic materials since they exhibit different responses to stresses applied in different directions depending on how the fibers are aligned or angled within the matrix. Other materials commonly used in bat constructions such as aluminum, wood and plastics are not anistropic and are thus limited in controlling bat performance; for example, radial stiffness is equal to longitudinal stiffness and cannot be graduated along the barrel length 1 . However, with composite materials, which are preferred, properties of bats made in accordance with the present invention, such as radial stiffness which determines bat performance can be controlled (i.e. designed to a given requirement) by altering such parameters as the fiber alignments along the barrel length 1 , and/or the type of fibers chosen, their demier or layout density and/or the thickness of the polymer composite structure. Generally, the fiber materials used are selected from a group consisting of fiberglass, graphite or carbon, aramid, boron, nylon, or hybrids of any of the foregoing, all of which are commercially available. The resins used to impregnate, wet out, and encapsulate or imbed the fiber materials are generally selected from a group consisting of epoxy, polyester, vinyl ester, urethane, or a thermoplastic such as nylon, or mixtures thereof. The first embodiment of the present invention, depicted in FIG. 4 , consists of a thin polymer composite stiffener 18 located internally within the barrel portion 9 generally in the sweetspot area 19 located in proximity to the middle or mid-section area of the barrel length 1 of a single wall tubular bat. The resultant stiffened bat results in a predetermined calculated lower performance, with an enlarged sweetspot 19 , as subsequently explained. The sweetspot area 19 of a baseball bat is generally referred to as that area along the barrel length 1 in which bat performance is greatest; that is, a ball struck within the sweetspot area 19 will travel further than a ball struck on either side of the sweetspot area. Typically, the sweetspot area 19 is located around the middle of the barrel length 1 and is in the order of about 2 inches to 4 inches in length when compared to overall barrel lengths 1 which range from approximately 4 inches to 16 inches or more. In actual practice, the performance of a baseball bat of the prior art follows a statistical normal distribution along the barrel length 1 , usually centered near the middle of the barrel length 1 in the sweetspot area 19 . FIG. 9 shows a typical bat performance distribution example with a 12-inch barrel length 1 . In FIG. 9 , the maximum bbs (one measure of bat performance standard) is 100 while most players would describe the sweetspot as being approximately 2 inch long (that is, the portion of the barrel length equal to or greater than 98 bbs). The bat of this particular sample meets a bat performance factor standard of 100 bbs maximum if so regulated. If the applicable regulatory body for the bat in the FIG. 9 example changed the bat performance standard from 100 bbs maximum to say 96 bbs maximum, the bat of the present invention could be provided with a specifically designed 4 inch polymer composite stiffener 18 located in the center of the barrel length 1 . FIG. 10 shows the bbs versus barrel length for this example. In FIG. 10 , in an example of the present invention, the combined barrel wall, with the polymer composite stiffener 18 present, is approximately twice as stiff in the center 2 inches of the sweetspot area 19 as in the 1 inch area immediately adjacent to the center or mid-section area on each side of the center area. The polymer composite stiffener 18 fiber type, fiber angles and thicknesses are designed such as to reduce the bbs from 100 to 96 in the center 2 inch area of the barrel length 1 and from 98 to 96 bbs in the 1 inch areas immediately adjacent to the center area. As a result of the present invention, the resultant typical example bat meets the lowered regulatory standard of 96 bbs with a sweetspot area 19 which has been increased in size by 100% (from 2 inches wide to 4 inches wide). At the same time the regions around points A and B have been introduced into the batting performance curve of FIG. 10 that were not present in the curve of FIG. 9 , with the more flattened portion there-between that is characteristic of an enlarged sweet spot. Alternatively, thickening the total barrel wall with the same material, the same thickness, and the same location as the stiffener results in the identical reduced bat performance. The first embodiment (i.e. as shown in FIG. 4 ) of the present invention is particularly suited to retrofitting used bats returned by players and making them legally playable under a revised standard. The thin polymer composite stiffener 18 of the present invention has a stiffener wall which is typically in the order of 0.010 inches to 0.040 inches in thickness, preferably 0.020″ with a length of 2 inches to 6 inches which is typically less than 50% of the barrel length, such as 16⅔% of the barrel length, as is apparent from FIG. 10 . A 4 inch stiffener, in a 12 inch barrel as referenced in FIG. 10 , would represent 33.3% of the barrel length; a 4 inch stiffener in a 16 inch barrel would represent 25%, and a 2 inch stiffener in a 16 inch barrel would represent 12.5% of the barrel length. The stiffener 18 is preferably bonded, fully or partially, to the main member 16 , or to the secondary member insert 13 of FIG. 7 or to the secondary member sleeve 14 of FIG. 8 , or combinations thereof on either the internal or external barrel walls, as shown in FIGS. 4 , 5 , 7 and 8 . Analogous to FIGS. 4 , 5 , 7 and 8 an alternative solution (since stiffness is proportional to thickness) to the stiffener 18 is to vary the barrel thickness 6 to the same extent and manner along any portion of the barrel length 1 of any bat according to the invention, including the bat of FIG. 6 in order to vary bat performance. The barrel portion's effective wall thickness in the mid-section can be greater by 8⅓% or more over the thickness of the barrel in the lateral, adjacent portions. Conversely, the barrel wall's thickness beyond its central portion, in the lateral regions proceeding towards the end portions of the barrel, may be at least 8⅓% thinner than the thickness of the barrel wall in the mid-section. Just as the stiffener wall may be typically in the order of 0.005 inches to 0.040 inches in thickness, or 0.010 inches to 0.040 inches in thickness, or 0.015 inches to 0.040 inches in thickness, or 0.015 inches to 0.030 inches, so too the analogous increase in barrel wall thickness along the mid-section may fall within the same ranges. A second embodiment of the present invention, as shown in FIG. 5 , is a single wall tubular baseball bat which in accordance with the present invention has a thin polymer composite stiffener 18 located externally to the barrel portion 9 generally in the sweetspot area 19 located in proximity to the middle area of the barrel length 1 . The resultant stiffened bat results in a calculated lower performance, with a bigger (longer) sweetspot 19 , as previously explained. A third embodiment of the present invention, as shown in FIG. 6 , is a single wall tubular polymer composite baseball bat which in accordance with the present invention has a localized area of fiber type of greater stiffness and/or angle change 20 resulting in increased radial stiffness generally in the sweetspot area 19 located in proximity to the middle area of the barrel length 1 . This embodiment applies equally well to double-wall and multi-wall (more than two walls) tubular all polymer composite baseball bats and is limited to newly designed polymer composite single wall, double-wall, and multi-walled new bats as opposed to field returned bats. The fiber types, and/or fiber angles, and/or fiber sizes, and/or composite thickness can be designed such as to graduate the radial stiffness of the barrel wall within the barrel portion 1 along its entire length. That is, the radial stiffness could be higher in the peak performance area (generally the sweetspot area 19 ) than in the lateral regions immediately adjacent to the sweetspot area 19 . In fact, by duplicating the increase in radial stiffness in the barrel mid-section as achieved by the stiffener 18 of FIG. 4 or 7 , the exact same bat performance change as shown in FIG. 10 and enlarged in sweetspot size 19 can be achieved by bats of FIG. 6 . Similarly, the alternative solution FIG. 6.1 showing a single wall tubular bat with a thickened barrel wall 21 and the alternative solution FIG. 6.3 showing a double wall tubular bat with a thickened barrel wall 21 , with the same material, location, and thickness of the stiffener 18 will result in the same bat performance change, as shown in FIG. 10 , and resultant enlarged sweetspot size 19 . A fourth embodiment of the present invention, as shown in FIG. 7 , is a double-wall tubular bat showing two separate members, a frame or main member 16 with an internal insert 13 as a secondary member full length in the barrel length 1 and, in accordance with the present invention, a stiffener 18 located internally within the insert 13 generally confined to the sweetspot area 19 , along the barrel length 1 . Though not shown, the stiffener 18 could be located externally to the main member 16 or between the main member 16 and the internal insert 13 . Also, though not shown, in multi-walled bats the stiffener 18 could be located internally, or externally, or between the members, or combinations thereof. A fifth embodiment of the present invention, as shown in FIG. 8 , is a double-wall tubular bat showing two separate members, a frame or main member 16 with an external sleeve 14 as a secondary member full length in the barrel length 1 and, in accordance with the present invention, a stiffener 18 , located externally to the sleeve 14 , generally in the area of the sweetspot area 19 along the barrel length 1 . Though not shown, the stiffener 18 could be located internally to the main member 16 and the external sleeve 14 . Also, though not shown, in multi-walled bats, the stiffener 18 could be located internally, or externally, or between the members, or combinations thereof. All embodiments of the present invention, as shown in FIGS. 4 , 5 , 6 , 7 , 8 , 12 C, 12 I, 13 A, 13 B, 13 C, 13 D, and 13 F, exhibit greater radial stiffness in the mid-section of the barrel length 1 relative to the lateral regions immediately adjacent to the mid-section, resulting in an enlarged sweetspot area 19 . Besides an enlarged sweetspot, other objectives of bats of the present invention include providing a user with a “soft feel”, having substantially less vibrations transmitted to the user's hand while striking a ball, unique impact sounds, and higher performance for average or below average players when making contact away from the normal sweetspot. These further objectives are achieved by bats of the present invention with secondary members with a variable outside diameter and by bats with two or more independent annular secondary members internally located along the inside diameter of the external bat frame. All bats of the present invention shown in FIG. 12 are characterized by inventive primary secondary members, or inserts 13 , located internally within an external main member, or frame 16 , with frame wall thickness 44 , within the barrel length 1 of the hitting portion of the bat. The primary secondary member 13 has an inner surface 53 , an outer surface 55 , an inner diameter 29 , an outer diameter 25 , a wall thickness 27 , a length 26 , a proximal end 58 , and a distal end 59 . Not shown in the FIGS. 12 and 13 bats is the normal handle portion located adjacent to the taper proximal portion and knob located at the proximal end of the frame 16 traditional bats. A traditional endcap 21 encloses the distal end 49 of the barrel portion 9 . The inventive primary secondary members 13 of the bats of FIG. 12 have outer diameters 25 that vary along the majority of the barrel length 1 . The variations in outer diameter 25 of the inserts 13 in all bats of FIGS. 12 are dimensioned to produce two or more contact areas 30 with the inside surface 45 of the frame 16 . In some variants of the bats of FIG. 12 , the primary secondary member 13 contact areas 30 have substantially flattened portions of constant maximum outer diameter, while in others the contact portions are much smaller. The contact areas 30 create at least one enclosed air cavity 22 with a maximum air cavity thickness 23 of at least 0.010″. The air cavities 22 of the present invention are closed at both ends to produce the desired feel and sound objectives upon ball contact. Varying positioning and quantities of the air cavities 22 , and contact areas 30 , produce bats with different performance levels, feel, and sound upon barrel portion 9 impact with a ball. To produce the desired unique soft bat feel and sound upon impact, the ideal thickness 23 of the air cavities 22 has been found by field testing to be 0.020″ to 0.050″ which is considerably thicker than prior art bats, where any such air spaces exist only due to manufacturing tolerances of the frame 16 and secondary member 13 . The air cavities 22 of the present invention can be filled with an elastomeric material with further performance, feel, and sound effects. Such prior art secondary members 13 do not have variable outer diameters. Due to the variable outer diameter 25 , all bats of FIG. 12 can have variable radial stiffness along the barrel length 1 . However, when the frame 16 and/or the primary secondary member 13 is made with composite materials, fiber types and laminating angles can be manipulated to achieve either constant or variable radial stiffness along the barrel length 1 regardless of dimensional variations. As seen in FIGS. 12A through 12F bats of the present invention are further characterized by the inventive primary secondary member 13 having a variable outer diameter 25 and a variable inner diameter 29 . The variable outer diameter 25 of the insert 13 produces variations in the surface profile of the insert 13 which are generally reflected by a corresponding profile on the inner surface 53 of the insert 13 wall. The resulting total bat wall thickness 6 variations along the barrel length 1 vary the performance, feel, and sound of the bats of FIGS. 12A through 12F . The bat variant of FIG. 12A has a single annular air cavity 22 where the external frame 16 wall acts independently of the insert 13 wall until the contact force between the ball and the external frame 16 increases enough to deflect the external frame inner surface 45 into contact with the insert's outer surface 55 . At that point, the two members 16 and 13 act together, thus creating a non-linear spring. This decreases the peak contact force between the ball and the bat, which reduces the energy losses in the ball, and therefore improves performance. The bat variant of FIG. 12B has an insert 13 outside diameter 25 which increases near the barrel mid-portion 50 , narrowing the air cavity 22 thickness. This reduces the performance improvement due to the effect of the gap, discussed in the previous paragraph, near the mid-portion 50 of the barrel length 1 and therefore gives a more uniform bat performance along the barrel length 1 . The bat variant of FIG. 12C is similar to 12 B where the insert 13 makes contact with the frame 16 inner surface 45 near the mid-portion 50 of the barrel length 1 at the insert 13 proximal 58 and distal 59 portions near the barrel ends. This eliminates the performance improvement imparted on the bat by the air cavity 22 at the barrel mid-portion 50 , but creates two independent annular air cavities 22 away from the barrel mid-portion 50 . The bat variant of FIG. 12D has an insert 13 where the outside diameter 25 oscillates, or varies periodically along the barrel length 1 . When the period of the oscillations is reduced the insert 13 becomes stiffer and stronger for a given weight, or lighter for a given stiffness. The radial stiffness of the insert 13 increases with increased insert wall thickness 27 , reduced period of oscillation, or increased magnitude of oscillation. The bat variant of FIG. 12E has an insert 13 where the outside diameter 25 oscillates, or varies periodically along the barrel length 1 , and where the period of the oscillation increases away from the mid-portion 50 of the barrel length 1 . The resultant reduced radial stiffness away from the sweetspot creates a more uniform performance along the barrel length 1 . The bat variant of FIG. 12F is a triple wall version of the bat of FIG. 12A created by an additional secondary member 31 . Though not shown, additional such members could be added to create a multi-wall bat with more than three walls. Similarly, though not shown, additional secondary members 31 of any configuration could be added to the bats of FIGS. 12B , 12 C, 12 D, and 12 E. FIGS. 12G through 12L depict bats characterized by an inventive primary secondary member 13 with a variable outer diameter 25 and a constant inner diameter 29 along the barrel length 1 . Otherwise, the bat variants of FIGS. 12G through L are similar to the bat variants of FIGS. 12A through F. In another embodiment of the present invention, the bats of FIG. 13 have two or more independent annular, or ring-like, secondary members 61 of similar cross-section shape of variable dimensions with individual length 62 , along the barrel portion 19 , less than one-half the barrel portion length 1 and are internally located along the inner surface 45 of the external frame 16 . The annular secondary members 61 have a length 62 , a wall thickness 63 , an inner surface 64 , an inner diameter 65 , an outer surface 66 , and an outer diameter 67 . The bat variant of FIG. 13A has the external frame 16 reinforced by a series of independent inner annular secondary members 61 generally in the form of annular rings. The secondary members 61 have a common outer diameter 67 which is equal to or less than the inner diameter 25 of the frame 16 and are generally thicker near the barrel mid-portion 50 of the barrel length 1 and thinner away from it. The rings 61 are generally thicker towards the barrel distal end 49 and thinner towards the barrel proximal end 48 because the bat is moving faster at the distal end 49 . Although not shown, the annular secondary members 61 could be of constant thickness and have varying material properties to accomplish varying radial stiffness and resultant more uniform performance. The bat variant of FIG. 13B has an external frame 16 reinforced by a series of independent annular secondary members 61 in the form of annular rings, in combination with an inner additional secondary continuous member 31 extending along the majority of the barrel length 1 . The annular secondary members 61 provide a more uniform bat performance along the barrel length, while the inner additional secondary member 31 supports the impact force. The bat variant of FIG. 13C is similar to that of 13 B; however, the annular secondary members 61 have a constant inner diameter 29 . The bat variant of FIG. 13D has internal annular secondary members 61 with a uniform inner diameter 29 and outer diameter 25 , which create closed air cavities 22 . The bat variant of FIG. 13E has an external frame 16 and axially continuous inner additional secondary member 31 with a series of annular secondary members 61 between the two. One candidate for the intermediate members 61 is a series of elastomeric O-rings with higher stiffness near the barrel mid portion 50 . The bat variant of FIG. 13F has an axially continuous inner additional secondary member 31 that is thicker in its mid-portion and could, or could not be, in contact with the external frame 16 near the barrel mid-portion 50 and has a reduced outer diameter at the barrel proximal 48 and distal 49 ends. The bat has two or more annular secondary members 61 located at the barrel portion 9 proximal 48 and diesel 49 ends. In effect, this bat is double walled at the barrel mid-portion 50 and triple walled away from the barrel mid-portion 50 , giving more uniform bat performance along the barrel length 1 resulting in a broadened sweetspot. The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. CONCLUSION The foregoing has constituted a description of specific embodiments showing how the invention may be applied and put into use. These embodiments are only exemplary. The invention in its broadest, more specific aspects, is further described and defined in the claims which now follow. These claims, and the language used therein, are to be understood in terms of the variants of the invention which have been described. They are not to be restricted to such variants, but are to be read as covering the full scope of the invention as is implicit within the invention and the disclosure that has been provided herein. The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

A multi-walled, tubular baseball bat has a barrel portion with a mid-section wherein the radial stiffness of the overall barrel wall varies along the barrel length to provide an enlarged sweetspot, improved soft feel and performance, plus unique sounds upon impact. The bat has a frame with a barrel portion of consistent diameter. A secondary member, or members, of tubular form extend internally along the barrel. The secondary member provides the required radial stiffness variation by: 1) variations in the thickness of the wall of the secondary member or by, 2) secondary members with unique geometric external surface profiles or by, 3) the presence of functional air cavities, with or without closed ends, between the main bat frame and the secondary member or members or by, 4) the presence of numerous annular secondary members located side by side less than one-half the length of the barrel portion.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a divisional application of U.S. application Ser. No. 13/577,288, which is a National Stage of PCT/JP2011/053650, filed Feb. 21, 2011. The disclosures of application Ser. No. 13/577,288 and PCT/JP2011/053650 are incorporated by reference herein in their entireties. The present application also claims priority of Japanese application 2010-040420, filed Feb. 25, 2010. TECHNICAL FIELD [0002] The present invention relates to, for example, a composition for an optical material, and specifically to, for example, a composition for an optical material which is preferable for an optical material such as a plastic lens, a prism, an optical fiber, an information recording substrate, a filter or the like, especially a plastic lens. BACKGROUND ART [0003] Plastic materials are lightweight, highly tough and easy to be dyed, and therefore are widely used recently for various types of optical materials, especially eyeglass lenses. Optical materials, especially eyeglass lenses, are specifically required to have, as physical properties, low specific gravity, high transparency and low yellow index, high heat resistance, high strength and the like, and as optical properties, high refractive index and high Abbe number. A high refractive index allows a lens to be thinner, and a high Abbe number reduces the chromatic aberration of a lens. However, as the refractive index is increased, the Abbe number is decreased. Thus, it has been studied to improve both of the refractive index and the Abbe number. Among methods which have been proposed, a representative method uses an episulfide compound as described in Patent Document 1. [0004] Meanwhile, in order to improve the oxidation resistance, Patent Document 2 proposes adding a thiol compound to an episulfide compound. [0005] It has also been studied to improve the refractive index. Patent Documents 3 and 4 propose a composition containing sulfur, episulfide and thiol. [0006] However, these composition containing thiol have a problem of being clouded when being polymerized and thus cured. These composition are to be used for optical materials. Therefore, if the composition are clouded after being cured, the composition become all defective. This causes a massive loss. Accordingly, a technique for estimating, on a pre-curing stage, whether the composition will be clouded or not after being cured, so that the composition is determined as being good or not has been desired. CITATION LIST Patent Literature [0007] Patent Document 1: Japanese Laid-Open Patent Publication No. H9-110979 [0008] Patent Document 2: Japanese Laid-Open Patent Publication No. H10-298287 [0009] Patent Document 3: Japanese Laid-Open Patent Publication No. 2001-2783 [0010] Patent Document 4: Japanese Laid-Open Patent Publication No. 2004-137481 SUMMARY OF INVENTION Technical Problem [0011] A problem to be solved by the present invention is to provide a composition for an optical material comprising polythiol which can be estimated, on a pre-polymerization/curing stage, as being clouded or not clouded after being cured, and thus can be determined as being good or defective. Solution to Problem [0012] As a result of accumulating active studies in light of such circumstances, the present inventors solved the problem by, for example, a composition for an optical material comprising polythiol having an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after being stored at 50° C. for 7 days, and episulfide; and thus achieved the present invention. [0013] Namely, the present invention is as follows. [0014] <1> A composition for an optical material comprising polythiol having an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after being stored at 50° C. for 7 days, and episulfide. [0015] <2> The composition for an optical material according to <1> above, further comprising sulfur. [0016] <3> The composition for an optical material according to <2> above, wherein the episulfide and the sulfur are preliminarily polymerized. [0017] <4> The composition for an optical material according to <2> above, wherein 10% or more of the sulfur is preliminarily polymerized with the episulfide. [0018] <5> The composition for an optical material according to any one of <1> through <4> above, which is obtained as a result of degassing. [0019] <6> An optical material obtained by polymerizing the composition for an optical material according to any one of <1> through <5> above. [0020] <7> The optical material according to <6> above, which is obtained as a result of annealing the post-polymerization composition for an optical material. [0021] <8> A method for producing a composition for an optical material, comprising the step of mixing polythiol having an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after being stored at 50° C. for 7 days, and episulfide. [0022] <9> The method for producing a composition for an optical material according to <8> above, further comprising the step of incorporating sulfur. [0023] <10> The method for producing a composition for an optical material according to <8> or <9> above, further comprising the step of degassing. Advantageous Effects of Invention [0024] According to the present invention, it has now become possible to provide, for example, a composition for an optical material containing polythiol which can be estimated, on a pre-polymerization/curing stage, as being clouded or not clouded after being polymerized and thus cured, and so can be determined as being good or defective. Provision of such a composition has been difficult with the conventional art. DESCRIPTION OF EMBODIMENTS [0025] According to the present invention, any of all polythiol compounds is usable. Specific examples thereof include methanedithiol, 1,2-dimercaptoethane, 2,2-dimercaptopropane, 1,3-dimercaptopropane, 1,2,3-trimercaptopropane, 1,4-dimercaptobutane, 1,6-dimercaptohexane, bis(2-mercaptoethyl)sulfide, 1,2-bis(2-mercaptoethylthio)ethane, 1,5-dimercapto-3-oxapentane, 1,8-dimercapto-3,6-dioxaoctane, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 2-mercaptomethyl-1,3-dimercaptopropane, 2-mercaptomethyl 1,4-dimercaptopropane, 2-(2-mercaptoethylthio)-1,3-dimercaptopropane, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane, 1,1,1-tris(mercaptomethyl)propane, tetrakis(mercaptomethyl)methane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, ethyleneglycolbis(2-mercaptoacetate), ethyleneglycolbis(3-mercaptopropionate), 1,4-butanediolbis(2-mercaptoacetate), 1,4-butanediolbis(3-mercaptopropionate), trimethylolpropanetris(2-mercaptoacetate), trimethylolpropanetris(3-mercaptopropionate), pentaerythritoltetrakis(2-mercaptoacetate), pentaerythritoltetrakis(3-mercaptopropionate), 1,1-dimercaptocyclohexane, 1,2-dimercaptocyclohexane, 1,3-dimercaptocyclohexane, 1,4-dimercaptocyclohexane, 1,3-bis(mercaptomethyl)cyclohexane, 1,4-bis(mercaptomethyl)cyclohexane, 2,5-bis(mercaptomethyl)-1,4-dithiane, 2,5-bis(mercaptoethyl)-1,4-dithiane, 1,2-bis(mercaptomethyl)benzene, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, bis(4-mercaptophenyl)sulfide, bis(4-mercaptophenyl)ether, 2,2-bis(4-mercaptophenyl)propane, bis(4-mercaptomethylphenyl)sulfide, bis(4-mercaptomethylphenyl)ether, 2,2-bis(4-mercaptomethylphenyl)propane, and the like. [0026] Specific examples of preferable compounds among the above-listed compounds include bis(2-mercaptoethyl)sulfide, pentaerythritoltetrakis(2-mercaptoacetate), pentaerythritoltetrakis(3-mercaptopropionate), 2,5-bis(mercaptomethyl)-1,4-dithiane, 1,2-bis(2-mercaptoethylthio)-3-mercaptopropane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 1,3-bis(mercaptomethyl)benzene, and 1,4-bis(mercaptomethyl)benzene. Specific examples of more preferable compounds include bis(2-mercaptoethyl)sulfide and 1,3-bis(mercaptomethyl)benzene. Bis(2-mercaptoethyl)sulfide is most preferable. [0027] According to the present invention, the turbidity is measured by an integrating sphere type turbidimeter on the basis of the kaolin standard solution in conformity to JIS K0101. The acceleration is measured after polythiol is stored at 50° C. for 7 days. [0028] After these measurements, polythiol having an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after being stored at 50° C. for 7 days is used. Preferably, the initial turbidity, namely, the turbidity immediately before storage at 50° C. for 7 days is 0.3 ppm or less, and the turbidity after storage at 50° C. for 7 days is 0.4 ppm or less. More preferably, the initial turbidity is 0.2 ppm or less, and the turbidity after storage at 50° C. for 7 days is 0.3 ppm or less. [0029] When the initial turbidity exceeds 0.5 ppm or the turbidity after storage at 50° C. for 7 days exceeds 0.6 ppm, an optical material such as a post-polymerization/curing lens is clouded and is not usable. Accordingly, by measuring the initial turbidity and the turbidity after storage at 50° C. for 7 days of polythiol, the estimation on whether the polythiol will be clouded or not can be made in the state where the polythiol has not been polymerized/cured. Thus, the quality of the polythiol can be determined. [0030] The actual operation is conducted as follows. First, the initial turbidity of polythiol is measured. A part of the polythiol is taken out and stored at 50° C. for 7 days, and then the turbidity thereof is measured. In the case where both of the values are in the above-described ranges, an optical material formed of the polythiol will not be clouded. Thus, this polythiol is determined as being usable. [0031] Where the sum of polythiol and episulfide is 100 parts by weight, a polythiol compound used in the present invention is usually contained in an amount of 1 to 30 parts by weight, preferably 2 to 20 parts by weight, and especially preferably 3 to 15 parts by weight. [0032] According to the present invention, any of all episulfide compounds is usable. Specific examples thereof will be listed below regarding each type of compounds, i.e., compounds having a chain aliphatic structure, compounds having an aliphatic cyclic structure, and compounds having an aromatic structure. [0033] The compounds having a chain aliphatic structure include compounds expressed by the following formula (1): [0000] [0000] (where m represents an integer of 0 to 4, and n represents an integer of 0 or 1). [0034] The compounds having an aliphatic cyclic structure include compounds expressed by the following formula (2) or (3): [0000] [0000] (where p and q each represent an integer of 0 to 4). [0000] [0000] (where p and q each represent an integer of 0 to 4). [0035] The compounds having an aromatic structure include compounds expressed by the following formula (4): [0000] [0000] (where p and q each represent an integer of 0 to 4). [0036] Among the above-shown compounds, the compounds expressed by formula (1) above having a chain aliphatic structure are preferable. Specific examples thereof include bis(β-epithiopropyl)sulfide, bis(β-epithiopropyl)disulfide, bis(β-epithiopropyl)trisulfide, bis(β-epithiopropylthio)methane, 1,2-bis(β-epithiopropylthio)ethane, 1,3-bis(β-epithiopropylthio)propane, 1,4-bis(β-epithiopropylthio)butane, and bis(β-epithiopropylthioethyl)sulfide. Bis(β-epithiopropyl)sulfide (in formula (1) above, n=0) and bis(β-epithiopropyl)disulfide (in formula (1) above, m=0, n=1) are especially preferable. Bis(β-epithiopropyl)sulfide (in formula (1) above, n=0) is most preferable. [0037] Examples of the episulfide compounds having an aliphatic cyclic structure include 1,3- and 1,4-bis(β-epithiopropylthio)cyclohexane (in formula (2) above, p=0, q=0), 1,3- and 1,4-(β-epithiopropylthiomethyl)cyclohexane (in formula (2) above, p=1, q=1), bis[4-(β-epithiopropylthio)cyclohexyl]methane, 2,2-bis[4-(β-epithiopropylthio)cyclohexyl]propane, bis[4-(β-epithiopropylthio)cyclohexyl]sulfide, 2,5-bis(β-epithiopropylthio)-1,4-dithiane (in formula (3) above, p=0, q=0), 2,5-bis(β-epithiopropylthioethylthiomethyl)-1,4-dithiane, and the like. [0038] Examples of the episulfide compounds having an aromatic structure include 1,3- and 1,4-bis(β-epithiopropylthio)benzene (in formula (4) above, p=0, q=0), 1,3- and 1,4-bis(β-epithiopropylthiomethyl)benzene (in formula (4) above, p=1, q=1), bis[4-(β-epithiopropylthio)phenyl)]methane, 2,2-bis[4-(β-epithiopropylthio)phenyl]propane, bis[4-(β-epithiopropylthio)phenyl)]sulfide, bis[4-(β-epithiopropylthio)phenyl)]sulfine, 4,4-bis(β-epithiopropylthio)biphenyl, and the like. [0039] Where the sum of polythiol and episulfide is 100 parts by weight, an episulfide compound used in the present invention is usually contained in an amount of 70 to 90 parts by weight, preferably 80 to 98 parts by weight, and especially preferably 85 to 97 parts by weight. [0040] A composition for an optical material according to the present invention may further contain sulfur. When sulfur is used, it is preferable to react an episulfide compound with sulfur preliminarily. Such a preliminary polymerization reaction is performed, preferably under the conditions of at −10° C. to 120° C. for 0.1 to 240 hours, more preferably under the conditions of at 0° C. to 100° C. for 0.1 to 120 hours, and especially preferably under the conditions of at 20° C. to 80° C. for 0.1 to 60 hours. In order to promote the preliminary reaction, it is effective to use a catalyst. Preferable examples of the catalyst include 2-mercapto-1-methylimidazole, triphenylphosphine, 3,5-dimethylpyrazole, N-cyclohexyl-2-benzothiazolylsulfineamide, dipentamethylenethiuramtetrasulfide, tetrabutylthiuramdisulfide, tetraethylthiuramdisulfide, 1,2,3-triphenylguanidine, 1,3-diphenylguanidine, 1,1,3,3-tetramethyleneguanidine, aminoguanidineurea, trimethylthiourea, tetraethylthiourea, dimethylethylthiourea, zinc dibutyldithiocarbamate, zinc dibentyldithiocarbamate, zinc diethyldithiocarbamate, zinc dimethyldithiocarbamate, pipecorium pipecoryldithiocarbamate, and the like. In addition, it is preferable to consume 10% or more of sulfur by this preliminary polymerization reaction (where the amount of sulfur before the reaction is 100%), and it is more preferable to consume 20% or more of sulfur. The preliminary reaction may be performed in an optional atmosphere, for example, under inert gas such as air, nitrogen or the like, in a sealed state at normal pressure or at a raised or reduced pressure, or the like. In order to detect how much the preliminary reaction has proceeded, a liquid chromatograph or a refractive index meter can be used. [0041] Where the sum of polythiol and episulfide is 100 parts by weight, sulfur, which is used in a preferable embodiment of the present invention, is usually contained in an amount of 0.1 to 40 parts by weight, preferably 0.5 to 30 parts by weight, and especially preferably 5 to 25 parts by weight. [0042] According to the present invention, it is preferable to perform degassing (deaeration) of the composition for an optical material in advance. The degassing is performed under a reduced pressure before, during or after the mixture of a compound reactive with a part of, or all of, the components of the composition, a polymerization catalyst, and an additive. Preferably, the degassing is performed at a reduced pressure during or after the mixing. Preferably, the degassing is performed under the conditions of at a reduced pressure of 0.001 to 50 torr for 1 minute to 24 hours at 0° C. to 100° C. The degree of pressure reduction is preferably 0.005 to 25 torr, and more preferably 0.01 to 10 torr. The degree of pressure reduction may be varied within such a range. The degassing time is preferably 5 minutes to 18 hours, and more preferably 10 minutes to 12 hours. The temperature for the degassing is preferably 5° C. to 80° C., and more preferably 10° C. to 60° C. The temperature may be varied within such a range. When performing the aeration, updating the interface of the composition for a resin by stirring, blowing-in of gas, vibration by ultrasonic waves or the like is preferable in order to improve the effect of the degassing. A component which is removed by the degassing is mainly, for example, dissolved gas such as hydrogen sulfide or the like or a low boiling point substance such as thiol or the like. There is no specific limitation on the type of target of removal as long as the effect of the present invention is provided. [0043] In addition, filtrating out impurities from the composition for an optical material or pre-mixing materials of the composition by use of a filter having a pore diameter of about 0.05 to 10 μm for the purpose of refinement is preferable in order to improve the quality of the optical material according to the present invention. [0044] Hereinafter, a method for producing an optical material by polymerizing a composition for an optical material according to the present invention will be described. [0045] Examples of a catalyst usable for polymerizing and thus curing the composition for an optical material include amine, onium salts, and phosphine compounds. Specific examples thereof include amine, quaternary ammonium salts, quaternary phosphonium salts, tertiary sulfonium salts, secondary iodonium salts, and phosphine compounds. Among these, quaternary ammonium salts, quaternary phosphonium salts and phosphine compounds are highly compatible with the composition and are preferable. Quaternary phosphonium salts are more preferable. Specific examples of the preferable compounds include quaternary ammonium salts such as tetra-n-butylammoniumbromide, tetraphenylammoniumbromide, triethylbenzylammoniumchloride, cetyldimethylbenzylammoniumchloride, 1-n-dodecylpyridiniumchloride, and the like; quaternary phosphonium salts such as tetra-n-butylphosphoniumbromide, tetraphenylphosphoniumbromide, and the like; and phosphine compounds such as triphenylphosphine and the like. Among these compounds, triethylbenzylammoniumchloride and tetra-n-butylphosphoniumbromide are more preferable, and tetra-n-butylphosphoniumbromide is most preferable. The polymerization catalysts may be used independently or in a mixture of two or more. [0046] The amount of the polymerization catalyst varies in accordance with the components, mixing ratio and polymerization/curing method of the composition and thus cannot be unconditionally determined. The amount of the polymerization catalyst is usually 0.001 wt. % or greater and 5 wt. % or less, preferably 0.01 wt. % or greater and 1 wt. % or less, and most preferably 0.01 wt. % or greater and 0.5 wt. % or less, with respect to the total amount of the composition for an optical material. When the amount of the polymerization catalyst is greater than 5 wt. %, the refractive index and the heat resistance of the cured product may be lowered and thus the cured product may be colored. When the amount of the polymerization catalyst is less than 0.001 wt. %, the composition may not be sufficiently cured and the heat resistance of the resultant product may be insufficient. [0047] For polymerizing and thus curing the composition for an optical material, a polymerization adjusting agent may be optionally added for the purpose of extending the pot life or dispersing the polymerization heat. As the polymerization adjusting agent, any of the group 13 through 16 halides in the long form periodic table is usable. Among these compounds, preferable compounds include halides of silicon, germanium, tin and antimony. More preferable compounds include chlorides of germanium, tin and antimony having an alkyl group. Specific examples of the more preferable compounds include dibutyltindichloride, butyltintrichloride, dioctyltindichloride, octyltintrichloride, dibutyldichlorogermanium, butyltrichlorogermanium, diphenyldichlorogennanium, phenyltrichlorogermanium, and triphenylantimonydichloride. A specific example of most preferable compounds is dibutyltinchloride. The polymerization adjusting agents may be used independently or in a mixture of two or more. [0048] The amount of the polymerization adjusting agent is usually 0.0001 wt. % to 5.0 wt. %, preferably 0.0005 wt. % to 3.0 wt. % or less, and most preferably 0.001 wt. % to 2.0 wt. % or less, with respect to the total amount of the composition for an optical material. [0049] For polymerizing and thus curing the composition for an optical material according to the present invention and thus for obtaining an optical material, any of additives such as a known antioxidant, ultraviolet absorber, blueing agent and the like can be added to improve the practicality of the material to be obtained. [0050] Preferable examples of the antioxidant include phenol derivatives. Among these, preferable compounds include polyhydric phenols and halogen-substituted phenols. More preferable compounds include catechols, pyrogallols, alkyl-substituted catechols. Most preferable compounds include catechols and pyrogallols. Preferable examples of the ultraviolet absorber include benzotriazole-based compounds. Specific examples of the preferable compounds among these compounds include 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole, 5-chloro-2-(3,5-di-tert-butyl-2-hydroxyphenyl)-2H-benzotriazole, 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole, 2-(3,5-di-tert-pentyl-2-hydroxyphenyl)-2H-benzotriazole, 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-2H-benzotriazole, 2-(2-hydroxy-4-octyloxyphenyl)-2H-benzotriazole, and 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole. Preferable examples of the blueing agent include anthraquinone-based compounds. [0051] In the case where the composition for an optical material according to the present invention is easily delaminated from the mold during the polymerization, a known external and/or internal adhesiveness improving agent can be used to control and improve the adhesiveness of the cured product to be obtained to the mold. Examples of the adhesiveness improving agent include known silane coupling agents, titanate compounds and the like. These adhesiveness improving agents may be used independently or in a mixture of two or more. The amount of the adhesiveness improving agent is usually 0.0001 wt. % to 5 wt. % with respect to the total amount of the composition for an optical material. By contrast, in the case where the composition for an optical material according to the present invention is difficult to be delaminated from the mold after the polymerization, a known external and/or internal releasing agent can be used to improve the releasability, from the mold, of the cured product to be obtained. Examples of the releasing agent include fluorine-based nonion surfactants, silicon-based nonion surfactants, ester phosphate, acid ester phosphate, oxyalkylene-type acid ester phosphate, alkali metal salts of acid ester phosphate, alkali metal salts of oxyalkylene-type acid ester phosphate, metal salts of higher fatty acid, higher fatty acid ester, paraffin, wax, higher aliphatic amide, higher aliphatic alcohol, polysyloxanes, aliphatic amineethyleneoxide adducts, and the like. These releasing agents may be used independently or in a mixture of two or more. The amount of the releasing agent is usually 0.0001 wt. % to 5 wt. % with respect to the total amount of the composition for an optical material. [0052] A method for producing an optical material by polymerizing and thus curing a composition for an optical material according to the present invention is, in more detail, as follows. The components of the composition, and additives such as the antioxidant, ultraviolet absorber, polymerization catalyst, radical polymerization initiator, adhesiveness improving agent, releasing agent and the like described above may be all mixed together in the same vessel while being stirred; the components and additives may be added step by step and mixed; or different groups of the components and additives may be mixed separately and then the groups may be added together in the same vessel. The components and sub components may be mixed in any order. There is basically no specific limitation on the set temperature, the time and the like for mixing as long as the components and additives are sufficiently mixed. [0053] The composition for an optical material obtained as a result of the above-described reaction and processing is injected into a glass or metal mold, and is heated or irradiated with active energy rays such as ultraviolet rays or the like, so that the polymerization/curing proceeds. Then, the resultant substance is removed from the mold. In this manner, the optical material is produced. For producing an optical material, the polymerization/curing of the composition for an optical material is preferably performed by heating. In this case, the curing time is 0.1 to 200 hours, usually 1 to 100 hours. The curing temperature is −10° C. to 160° C., usually −10° C. to 140° C. The polymerization can be performed by holding the polymerization temperature for a prescribed time period, increasing the temperature at a rate of 0.1° C. to 100° C./hour, decreasing the temperature at a rate of 0.1° C. to 100° C./hour, or a combination thereof. In the process for producing an optical material according to the present invention, annealing the post-polymerization/curing product at a temperature of 50° C. to 150° C. for about 10 minutes to 5 hours is preferable in order to remove distortion from the optical material. In addition, surface treatment such as dyeing, hard-coating, anti-impact-coating, reflection prevention, provision of antifogging property or the like may be performed. EXAMPLES [0054] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples. The evaluation was performed by the following method. [0055] Turbidity: The initial turbidity and the turbidity after storage at 50° C. for 7 days of polythiol were measured by use of T-2600DA turbidimeter produced by Tokyo Denshoku Co., Ltd. [0056] Transparency: Ten lenses having a lens diameter of 70 mm and a degree of +5D were produced by use of optical materials produced by polymerization of compositions for an optical material. The lenses were observed in a darkroom under fluorescent light. The optical materials were evaluated as follows: the optical material used for producing the ten glasses, none of which was clouded, was rated “4”; the optical material used for producing the ten glasses, nine of which were not clouded, was rated “3”; the optical material used for producing the ten glasses, seven or eight of which were not clouded, was rated “2”; and the optical material used for producing the ten glasses, six or less of which were not clouded, was rated “1”. The optical materials rated “2” or higher are acceptable. Example 1 [0057] A composition for an optical material, and an optical material, according to the present invention were produced by use of bis(1-mercaptoethyl)sulfide having an initial turbidity of 0.15 and a turbidity of 0.15 after storage at 50° C. for 7 days in accordance with production method A described below. The transparency of the obtained optical material was good and “4”. The results are shown in Table 1. Examples 2 Through 6 [0058] A composition for an optical material, and an optical material, according to the present invention were produced by use of bis(2-mercaptoethyl)sulfide having an initial turbidity and a turbidity after storage at 50° C. for 7 shown in Table 1 in accordance with the production method shown in Table 1. The results are shown in Table 1. Examples 7 Through 12 [0059] A composition for an optical material, and an optical material, according to the present invention were produced by use of 1,3-bis(mercaptomethyl)benzene having an initial turbidity and a turbidity after storage at 50° C. for 7 shown in Table 1 in accordance with the production method shown in Table 1. The results are shown in Table 1. Comparative Examples 1 Through 4 [0060] A composition for an optical material, and an optical material, were produced by use of bis(2-mercaptoethyl)sulfide having an initial turbidity and a turbidity after storage at 50° C. for 7 shown in Table 1 in accordance with the production method shown in Table 1. The results are shown in Table 1. Comparative Examples 5 Through 8 [0061] A composition for an optical material, and an optical material, were produced by use of 1,3-bis(2-mercaptomethyl)benzene having an initial turbidity and a turbidity after storage at 50° C. for 7 shown in Table 1 in accordance with the production method shown in Table 1. The results are shown in Table 1. [0062] The production methods used in the examples and the comparative examples were as follows. Method A: [0063] To a composition containing 5 parts by weight of bis(2-mercaptoethyl)sulfide and 95 parts by weight of bis(β-epithiopropyl)sulfide, 0.1 parts by weight of tetra-n-butylphosphoniumbromide was added as a polymerization catalyst. These compounds were mixed uniformly at room temperature and degassed to prepare a composition for an optical material. The composition for an optical material was injected into a mold, heated for 20 hours from 20° C. to 100° C. to be polymerized and thus cured, and then removed from the mold. Thus, an optical material was obtained. Method B: [0064] To 78 parts by weight of bis(β-epithiopropyl)sulfide and 14 parts by weight of sulfur, 0.5 parts by weight of mercaptomethylimidazole was added. These compounds were preliminarily polymerized and thus cured at 60° C. The consumption ratio of sulfur at this point was 50% by an HPLC analysis (GPC mode). After the resultant substance was cooled down to 20° C., a mixture solution of 7 parts by weight of bis(2-mercaptoethyl)sulfide, 0.2 parts by weight of dibutyltindichloride, and 0.03 parts by weight of tetra-n-butylphosphoniumbromide was added. These compounds were mixed uniformly and degassed to prepare a composition for an optical material. The composition for an optical material was injected into a mold, heated for 20 hours from 20° C. to 100° C. to be polymerized and thus cured, and then removed from the mold. Thus, an optical material was obtained. Method C: [0065] To a composition containing 5 parts by weight of 1,3-bis(mercaptomethyl)benzene and 95 parts by weight of bis(β-epithiopropyl)sulfide, 0.1 parts by weight of tetra-n-butylphosphoniumbromide was added as a polymerization catalyst. These compounds were mixed uniformly at room temperature and degassed to prepare a composition for an optical material. The composition for an optical material was injected into a mold, heated for 20 hours from 20° C. to 100° C. to be polymerized and thus cured, and then removed from the mold, Thus, an optical material was obtained. Method D: [0066] To 78 parts by weight of bis(β-epithiopropyl)sulfide and 14 parts by weight of sulfur, 0.5 parts by weight of mercaptomethylimidazole was added. These compounds were preliminarily polymerized and thus cured at 60° C. The consumption ratio of sulfur at this point was 46% by an HPLC analysis (GPC mode). After the resultant substance was cooled down to 20° C., a mixture solution of 7 parts by weight of 1,3-bis(mercaptomethyl)benzene, 0.2 parts by weight of dibutyltindichloride, and 0.03 parts by weight of tetra-n-butylphosphoniumbromide was added. These compounds were mixed uniformly and degassed to prepare a composition for an optical material. The composition for an optical material was injected into a mold, heated for 20 hours from 20° C. to 100° C. to be polymerized and thus cured, and then removed from the mold. Thus, an optical material was obtained. Preliminary Experiment [0067] To 100 parts by weight of bis(β-epithiopropyl)sulfide to be used in the examples and the comparative examples, 0.1 parts by weight of tetra-n-butylphosphoniumbromide was added as a polymerization catalyst. These compounds were mixed uniformly at room temperature and degassed. The resultant mixture was injected into a mold, heated for 20 hours from 20° C. to 100° C. to be polymerized and thus cured, and then removed from the mold. Thus, an optical material was obtained. The transparency of the optical material was good and “4”. An episulfide compound which was confirmed to maintain a good transparency even after being polymerized and thus cured in this manner was used. [0000] TABLE 1 Initial Post-storage Other turbidity turbidity main Polymerization Trans- Example Polythiol compound value value Episulfide compound component method parency Example 1 Bis(2-mercaptoethyl)sulfide 0.15 0.15 Bis(β-epithiopropyl)sulfide — A 4 Example 2 Bis(2-mercaptoethyl)sulfide 0.15 0.15 Bis(β-epithiopropyl)sulfide Sulfur B 4 Example 3 Bis(2-mercaptoethyl)sulfide 0.26 0.28 Bis(β-epithiopropyl)sulfide — A 3 Example 4 Bis(2-mercaptoethyl)sulfide 0.26 0.28 Bis(β-epithiopropyl)sulfide Sulfur B 3 Example 5 Bis(2-mercaptoethyl)sulfide 0.32 0.43 Bis(β-epithiopropyl)sulfide — A 2 Example 6 Bis(2-mercaptoethyl)sulfide 0.32 0.43 Bis(β-epithiopropyl)sulfide Sulfur B 2 Example 7 1,3-bis(2-mercaptomethyl)benzene 0.15 0.17 Bis(β-epithiopropyl)sulfide — C 4 Example 8 1,3-bis(2-mercaptomethyl)benzene 0.15 0.17 Bis(β-epithiopropyl)sulfide Sulfur D 4 Example 9 1,3-bis(2-mercaptomethyl)benzene 0.26 0.33 Bis(β-epithiopropyl)sulfide — C 3 Example 10 1,3-bis(2-mercaptomethyl)benzene 0.26 0.33 Bis(β-epithiopropyl)sulfide Sulfur D 3 Example 11 1,3-bis(2-mercaptomethyl)benzene 0.45 0.58 Bis(β-epithiopropyl)sulfide — C 2 Example 12 1,3-bis(2-mercaptomethyl)benzene 0.45 0.58 Bis(β-epithiopropyl)sulfide Sulfur D 2 Comparative Bis(2-mercaptoethyl)sulfide 0.18 0.63 Bis(β-epithiopropyl)sulfide — A 1 example 1 Comparative Bis(2-mercaptoethyl)sulfide 0.18 0.63 Bis(β-epithiopropyl)sulfide Sulfur B 1 example 2 Comparative Bis(2-mercaptoethyl)sulfide 0.51 0.51 Bis(β-epithiopropyl)sulfide — A 1 example 3 Comparative Bis(2-mercaptoethyl)sulfide 0.51 0.51 Bis(β-epithiopropyl)sulfide Sulfur B 1 example 4 Comparative 1,3-bis(2-mercaptomethyl)benzene 0.19 0.65 Bis(β-epithiopropyl)sulfide — C 1 example 5 Comparative 1,3-bis(2-mercaptomethyl)benzene 0.19 0.65 Bis(β-epithiopropyl)sulfide Sulfur D 1 example 6 Comparative 1,3-bis(2-mercaptomethyl)benzene 0.55 0.57 Bis(β-epithiopropyl)sulfide — C 1 example 7 Comparative 1,3-bis(2-mercaptomethyl)benzene 0.55 0.57 Bis(β-epithiopropyl)sulfide Sulfur D 1 example 8 [0068] In each of the above examples, a composition for an optical material using polythiol fulfilling the conditions that the initial turbidity is 0.5 ppm or less and the turbidity after storage at 50° C. for 7 days is 0.6 ppm or less was polymerized. As a result, post-curing cloudiness was prevented and a high transparency was realized. Thus, according to the present invention, it can be estimated, before the polymerization reaction, whether a composition for an optical material will be clouded or not after being polymerized and thus cured. Thus, it can be determined whether the composition is good or not. Therefore, only an optical material having good properties can be selectably produced. As a result, the composition for an optical material can be effectively utilized and also a superb optical material can be produced.

The present invention has an object of providing, for example, a composition for optical materials which contains a polythiol that can be predicted and assessed, in a stage prior to polymerization/curing, as being clouded or not clouded after polymerization/curing, and thus can be determined as being good or defective. According to the present invention, the above-described object is achieved by, for example, a composition for optical materials which comprises a polythiol that exhibits an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after the storage at 50° C. for 7 days, and an episulfide. Namely, an optical material made from a composition for optical materials which contains a polythiol satisfying the above turbidity requirements can be prevented from clouding to exhibit excellent transparency.

RELATED APPLICATIONS This application claims priority to U.S. Provisional application 60/713,936, which is incorporated herein by reference. FIELD OF THE INVENTION This invention relates to the area of automated musical instruments, particularly pianos, the invention also relates to the method of creating or authoring music sequences files for use with the automated musical instrument. BACKGROUND OF THE INVENTION Automated musical instruments, such as pianos, are well known in the art. Such instruments are typically acoustic instruments that use mechanical actuators to operate the instrument. The actuators receive commands of articulation events or music sequences to control or play the instrument. The music sequences are delivered to the instrument by a controller. There have been a number of attempts to have an automated instrument play in synchronization or accompaniment with a prerecorded CD or hard drive. Such attempts are described in U.S. Pat. Nos. 5,138,925, 5,300,725, 5,148,419 and 5,313,011. In order allow for synchronous play, those previous attempts rely upon timing information presented on a sub-channel of the CD to provide a common time frame for both the music sequences and the CD audio to reference. While such an arrangement is sufficient, it suffers from the limited resolution offered by the timing information of the CD sub-channel. The timing information of the CD sub-channel has a period or resolution of 13 milliseconds, which is not accurate enough for some piano sequences. The present invention described herein uses the timing inherent in the CD audio data as the time reference. By the use of this technique, the timing can have a period or resolution of 22.7 microseconds based upon the sample rate of 44.1 kHz of the digital audio data of the CD While listening to the automated instrument playing alone is entertaining for the user, some users desire to have the instrument play along with a commercial recording of a musical selection, thus allowing the user to experience the recorded selection accompanied by a live automated instrument. In early products for playing an automated piano in synchronism with a CD, the CD media contained music sequences that were pre-synchronized to a digital accompaniment music track encoded as linear PCM. For instance, the audio music track would be encoded as PCM on the left channel of the CD, and the music sequence, encoded as MIDI, would be encoded on the right channel. In the invention described herein, the system utilizes off the shelf commercially recorded CD, and music sequences specifically authored to play in synchronism with the musical selections on the CD. The music sequences are generally MIDI files stored on removable media such as SD cards and the like. One skilled in the art will recognize that there are many ways to deliver the music sequences, such as MIDI files, to the consumer and ultimately to the controller of the automated musical instrument, and SD cards are but one example. SUMMARY OF THE INVENTION The system described herein includes a controller for delivering the music sequences to the automated musical instrument. The controller is also in communication with a drive capable of playing digital media such as a CD. The controller, using the CD audio data as a time reference, delivers the music sequences to the automated musical instrument so that the instrument plays in synchronism with the selection playing on the CD. One skilled in the art will recognize that the controller could also host and act as the player for the music sequence with the appropriate software. The following terms and definitions are used in this specification. The definitions included herein are to add meaning to terms and are not meant to limit or otherwise supplant meanings that are understood by those skilled in the art. MIDI—Acronym for Musical Instrument Digital Interface. MIDI is a music industry standard for digitally communicating musical instrument articulation events as a sequence of one or more bytes per event. The standard includes mechanical, electrical and byte signaling specifications. MIDI Interface—A physical interface across which MIDI bytes are sent and/or received. MIDI Event—A byte sequence that encodes a single musical instrument articulation event such as ‘key on’ or ‘sustain pedal depressed.’ MIDI Sequence—A chronological sequence of time-stamped MIDI events that encapsulates a performance of one or more musical instruments. MIDI Sequencer—A device that plays a MIDI Sequence in real time for the purpose of reproducing a musical performance. Standard MIDI File (SMF)—A music industry standard for storing and retrieving MIDI Sequences to and from a digital data file commonly referred to as MIDI file. Pianomation—A system for translating MIDI events to electro-mechanical activity for the purpose of automating an acoustic piano, or other automated musical instrument. Controller—An electronic device used to drive Pianomation with music sequences, such as MIDI Events from various media. DVD—Acronym for the consumer electronics Digital Video Disc standard and media. CD Player—A device, such as an optical drive, that is capable of playing a CD. CD Player Subsystem—An electronic Subsystem used to play CDs such as an integrated CD player ASIC and related electronic components contained within a larger system such as a Controller. Music Sequence—A term used in this application to generically refer to a chronological sequence of time-stamped digital musical instrument articulation events that encapsulates a performance of one or more musical instruments. This could be a SMF, a MIDI Sequence, or an otherwise encoded sequence that achieves the same objective. Sync-Along CD—The technique described herein for synchronizing a music sequence to a CD Player or CD Player Subsystem. Sync-Along CD Device—The device that implements the technique. This device can either attach to or be contained within a controller. PCM—Acronym for Pulse Code Modulation. This term refers to the linear digital encoding of instantaneous audio amplitude at a constant sample rate. This is also referred to as uncompressed digital audio. In the present invention, the controller, through use of a CD drive and subsystem incorporated into the controller, acts as both the MIDI Sequencer and the CD playback device, so the controller has inherent and immediate knowledge of what CD audio track is being played and what that track's time progress is authored music sequences to accompany commercial CD release. Typically, these commercial CDs will contain musical performances and the object is to drive the automated musical instrument synchronously along with the CD. These pre-authored music sequences are synchronized to the digital audio stream of the CD per track. This means that a particular track is extracted from the CD by the authoring system. Once this is done, it is played by the authoring system which is simultaneously capturing a live piano performance along with it and converting that performance to a music sequence, typically in MIDI format. The time stamps use the CD's extracted digital audio stream as its source of time reference rather than some other system time. Hence, the resulting music sequence is synchronized to the CD track on any playback system as long as the playback system uses the CD's digital audio stream as its time reference. Once the music sequence is authored or pre-authored as the process is alternatively named, it is associated with a CD song in some way. Since the Sync-Along device or controller is always the renderer of the CD Audio, it has specific knowledge of the CD that is being played, i.e., its Volume ID, and is always aware of exactly what track is being played. As such, the specific Volume ID and track number are stored as either Meta Events within the MIDI Sequence, or as part of the filename of the MIDI Sequence, allowing the controller to recognize what music sequence matches the CD being played. Therefore, when a controller is instructed by the user to playback a particular track, the system loads the requested music sequence along with its Volume ID and associated track number and checks to make sure that that particular CD is loaded for playback. Playback of audio CDs is implemented by the controller by reading the digital audio data, commonly referred to as Redbook audio data, directly off of the CD and sending that data to its DAC Subsystem for rendering to an analog signal. The DAC Subsystem itself is regulated by the audio rate of the DAC, which will nominally run at 44.1 kHz—the CD Audio sample rate. Hence, the data itself is consumed at the CD audio data rate by the DAC Subsystem which, via its DMA progress status, then provides the controller with an accurate digital audio time-base. Once playback of the CD audio track has been initiated, the controller resets its internal sequencer time-base and monitors the progression of audio time as measured by the DAC Subsystem. As this digital audio time progresses, the controller submits the MIDI events to the Piano system in accordance with the event timestamps. Thus, the CD and the automated musical instrument are synchronized. Since the automated Piano is a solenoid-actuated system, there is a measurable time delay from the time it receives a MIDI Event and the time it can actually sound a note on the automated acoustic Piano. In practice, his time can be as low as 100 ms or as high as 500 ms. Although the time is variable, the controller fixes the absolute delay from event reception to note sounding at 500 ms. Because of this delay, the controller advances the assertion of MIDI events during playback by 500 ms relative to the song start in order to maintain absolute synchronization to the CD as perceived by the user. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the operational components of the system of the invention. FIG. 2 is a front view of a controller. FIG. 3 is a diagram showing the timely relationship between an analog audio output and a music sequence. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1 , the synchronization system 20 described herein includes a controller 22 , an automated musical instrument, such as a piano 24 , and an amplifier 26 and speaker 28 . The amplifier 26 and speaker 28 can be incorporated into the controller 22 in an alternate embodiment, and need not be separate devices. Similarly, the amplifier 26 and speaker 28 can be replaced with any combination of devices that will allow the user to hear the recorded material on the CD placed into the CD drive 40 of the controller 22 . Thus, it is beneficial for the housing of the controller 22 to include an audio output port for connection of the amplifier 26 and speaker 28 , or other device used to transduce the audio signal output from the controller 22 . In the preferred embodiment, the output port is a pair of RCA jacks 60 to allow play of the left and right audio channels of the CD, as shown in FIG. 2 . The controller 22 is connected to the automated musical instrument or piano 24 by a communication channel 35 capable of carrying the music sequences from the controller 22 to the piano 24 . In the preferred embodiment, the communication channel is a high speed UART serial channel. The controller 22 includes a CD drive 40 , a digital to analog converter (DAC) subsystem 42 , a microprocessor 45 , random access memory (RAM) 47 , read only memory (ROM) 49 such as flash memory or an SD card or other removable media, a display 51 , and user controls 53 . The CD drive 40 can be any optical drive capable of reading a CD meeting the redbook specification and outputting the digital music data and subchannels having information regarding the volume ID, track number and non-music data regarding the CD. The CD drive 40 shares a communications channel 54 with the microprocessor 45 to convey information regarding the CD to the microprocessor 45 , and to receive control commands from the microprocessor 45 . The CD drive 40 also shares a communications channel 56 with the DAC subsystem 42 . The communications channel 56 serves to send the digital audio data from the CD drive to the DAC subsystem 42 . The DAC subsystem 42 of the preferred embodiment processes the digital audio data and converts the digital information into an analog signal. In the preferred embodiment, the DAC subsystem has two main parts, one of which may be incorporated into the microprocessor 45 . The first part is a DMA controller. The DMA controller moves audio data from the processor's RAM 47 to the DAC without processor intervention, as one skilled in the art will recognize In the preferred embodiment, the DMA controller is built into the TriMedia microprocessor. The DAC subsystem 42 also includes a digital to analog converter. In the preferred embodiment, the digital to analog converter is model CS4226 manufactured by Cirrus Logic. The DAC subsystem communicates with the microprocessor 45 by communications channel 55 . The communications channel is used to send information to the microprocessor 45 , access RAM 47 in communication with the microprocessor 45 , and to receive control commands from the microprocessor 45 . Among the information shared with the microprocessor 45 is the DMA progress status, or information regarding how many units of the digital audio data have been processed or output by the DAC subsystem 42 . The DAC subsystem 42 outputs the analog signal to the amplifier 26 by communications channel 56 . Communication channel 56 may include an output port 60 in the housing of the controller 22 . In the preferred embodiment, the output port is a pair of RCA jacks. The microprocessor 45 is in communication with RAM 47 by communication channel 60 . In the preferred embodiment, the controller 22 has 1 gigabyte of RAM, although other amounts can be used. The microprocessor 45 is also in communication with ROM 49 by communications channel 61 . The ROM 45 is used to provide the music sequences, preferably MIDI files, to the controller 45 . In the preferred embodiment, the ROM 49 is an SD card. The controller 22 is provided with a slot or interface 48 that will accept the SD card and link the card to the communications channel 61 . On skilled in the art will recognize that other types of memory could be used for ROM 49 , provided the controller 22 has the appropriate interface and the microprocessor 45 has the corresponding inputs and software to accommodate the type of memory used. In the preferred embodiment, the microprocessor is a TriMedia manufactured by Philips. Other microprocessors can be used to accomplish the tasks described herein. For example, the microprocessor should be able to feed data to the DAC subsystem, monitor the data progress, and interface with the CD drive to read raw audio data if desired. The controller 22 includes a display 51 in communication with the microprocessor by communication channel 64 . The display is preferably an alpha numeric display capable of displaying information regarding the CD being played, as well as the music sequences available in ROM 49 . In the preferred embodiment the display 51 is a multi character fluorescent display. Other displays may be used to convey information to the user. The controller also includes user controls 53 in communication with the micro processor 45 by communication channel 67 . In the preferred embodiment, the user control 53 includes a knob that can be rotated to scroll through the available selections, and pressed to select the displayed selection, which determines the music sequence the controller 22 will play. One skilled in the art will recognize that the user controls 53 can be any type of device that allows the user to interact with the controller 22 . For instance the user controls 53 could be a push button, keyboard, or touch screen. In the preferred embodiment, the display shows the titles of the music sequences available for play by the controller. The number of titles displayed at any one time depends upon the size of the display used. The user manipulates user controls 53 to change the titles displayed until the desired title is displayed and selected for play. The titles are obtained from the files stored in ROM 49 . In the preferred embodiment, the ROM 49 contains music sequences corresponding to a particular commercial CD. The individual music sequences generally correspond to the tracks present on the commercial CD. The volume ID for the CD, and the track number are preferably stored as meta events in the music sequence. Alternately, the Volume ID and track number can form part of the file name for the music sequence file. The ROM 49 may also include a file to associate the song titles of the music sequence with the volume ID and track numbers of the CD. Thus, the controller 22 can display the song titles on the display 51 corresponding to the music sequences available in ROM 49 . The music sequences are authored to the CD using standard authoring software such as a Digital Performer sold by Motu. During the authoring process, which is familiar to those skilled in the art, the music sequence is stored in a file as articulation or MIDI events. The timing or reference of the articulation events is based upon the audio rate or sample rate of the CD. FIG. 2 shows the relationship between an analog audio signal 70 , such as the audio output of the DAC subsystem, and the articulation events 71 of a corresponding music sequence 72 . One skilled in the art will recognize that the analog signal 70 is created from the conversion of the digital audio data having a sample rate of 44.1 kHz, and that the authoring software relates the meta events to the timing of the digital audio data. Thus, when the CD is played in the CD drive 40 , the microprocessor 45 can access the DAC subsystem 42 to determine how many samples have passed since the beginning of play to obtain an accurate time base. Having that information, the microprocessor 45 can send the articulation event to the piano 24 at the correct time. In the preferred embodiment, the piano 24 is a solenoid actuated system, and as such has an inherent delay between the time it receives a meta event and the sounding of the note on the piano 24 . In order to account for this delay, the microprocessor 45 sends the meta event to the piano 24 at a discrete time in advance of the timestamp of the meta event. In the preferred embodiment, the discrete time is 500 ms. Thus, the microprocessor 45 sends the midi event to the piano 500 ms earlier than called for by the timestamp associated with the event in order to achieve playing of the piano 24 in absolute synchronization with the CD. In operation, the system 20 generally operates as outlined herein. One skilled in the art will recognize that the operation may vary depending upon the particular embodiment. The user selects a ROM device, such as a CD card, containing the music sequence files authored for a particular CD. The user inserts the ROM device into the slot or interface 48 on the face of the controller 22 , allowing the microprocessor 45 to access the files on the ROM device. The user also places the desired CD into the CD drive 40 . The microprocessor accesses the files on the ROM 49 and displays the titles of music selections available on the display 51 . The titles are displayed one at a time. In order to advance to the next available title, the user manipulates a user control 53 , which in the preferred embodiment is a rotatable knob. Rotation of the knob scrolls through the available music selections. When the desired music selection appears on the display 51 , the user manipulates a user control 53 to start play, which in this embodiment involves pressing the knob. One skilled in the art will recognize that other types of controls or interfaces can be used. In response, the microprocessor 45 accesses ROM 49 and loads the selected music sequence along with its volume ID and track number in to RAM 47 . The microprocessor 45 then quires the CD drive to obtain the volume ID of the CD in the drive to determine if the volume ID of the CD in the CD drive 40 matches the volume ID loaded into RAM 47 . If the volume ID does not match, the microprocessor displays on the display 51 indicia such as “insert CD” or other instructions to the user to indicate that the CD in the CD drive 40 does not match the CD for the ROM device selected. If the volume ID does match, play of the CD audio data can begin. To play the digital audio data, the microprocessor 45 resets an internal time sequencer and instructs the CD drive 40 to send the digital audio data to the DAC subsystem 42 . The DAC subsystem 42 converts the digital audio data to an analog signal, which is then output to an amplifier 26 for play on speaker 28 . The DAC also provides the microprocessor 45 with the time progress of the digital audio data processed by sending the microprocessor 45 timing information from the DAC subsystem's 42 DMA progress status. Monitoring this information, the microprocessor 45 knows what time it is relative to the start of the playing of the CD audio data. The microprocessor advances this time by a discrete amount, preferably 500 ms and tracks the time in its internal time sequencer. As the time in the internal time sequencer progresses, the microprocessor issues meta events to the piano 24 via communications channel 35 , thus allowing play of the piano in absolute synchronization with the CD being played. The embodiments described herein are mere examples of the teachings of the invention. As such, they are not intended to limit the scope of the claimed invention.

The invention disclosed is a system for playing a music sequence such as a MIDI file in synchronization with a prerecorded CD. The synchronization is accomplished by using the digital media sample rate as a common time base for progression of the playing of the digital media and the music sequence.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This invention is a formal application of a provisional application, filed on Dec. 18, 2000, Serial No, 60/256,735 and a continuation application filed Sep. 19, 2001, Ser. No. 09/956,727. FILED OF INVENTION [0002] This invention relates to a new design of a soft inner enclosure for the carrying case of an external data storage device or other electronic devices for shock protection of the external data storage device or other electronic devices in their storage, carrying and operating mode. BACKGROUND OF INVENTION [0003] The need of an enclosure for the protection of a variety of devices against shock has been around for a long time. A brief search and analysis of the prior art revealed the following US patents: [0004] U.S. Pat. No. 4,786,121 (November 1988, by Lyons), titled computer protective enclosure, teaches the usage of outside panels with inner linings to acoustically isolate and additionally protect the stored computer. The outside panels, or covers, are made of rigid materials such as wood, plastic and metal. The inner linings are made of foam plastic with a space between the inner linings and the computer. Furthermore, the enclosure is intended for affixing to building construction members or other stationary objects for stability. [0005] U.S. Pat. No. 4,846,340 (July 1989, by Walther), titled shock proof carrying enclosure for musical instrument, teaches the usage of an enclosure for the shock proof storage and carrying of a musical instrument like cello. However, in this case, the enclosed musical instrument is already retained within a rigid case to begin with. Therefore, effectively, the protective structure for the musical instrument itself consists of an inner rigid case and an outer flexible enclosure. [0006] U.S. Pat. No. 5,010,988 (April 1991, by Brown), titled expandable shock protected carrying case, teaches the usage of a carrying case for a lap top computer, printers, facsimiles and the like where the carrying case comprises of functional elements like handle, shoulder strap, compartments and accessory pockets. The disclosed wall structure consists of at least three layers, that is, an outer shell, an inner shell and a three-ply shock protection structure sandwiched in between. The outer shell is made of a substantially rigid yet soft material. The disclosed carrying case looks to be primarily used when the enclosed device is in its non-operating mode. Thus, for example, thermally insulating materials and related structural design are employed there to protect the enclosed device from temperature extremes. [0007] U.S. Pat. No. 6,034,841 (March 2000, by Albrecht, Khanna, Kumar and Sri-Jayantha), titled disk drive with composite sheet metal and encapsulated plastic, describes the usage of a metal base with integrally molded plastic peripheral flanges plus elastomeric comer bumpers for shock protection. As described, except for the elastomeric comer bumpers, all the other enclosure pieces are made of rigid material. [0008] As described in a pending application filed earlier by the inventor, a soft enclosure design for an external data storage device or other electronic devices in their storage, carrying and operating mode is disclosed. The inside shock absorbing layer of the soft enclosure design, now called inner enclosure for simplicity, provides many functions. Some examples of the functions are shock protection, heat dissipation, fire retardation, shielding against radio frequency interference, prevention of build up of static electricity and prevention of dirt penetration into the interior of the enclosure. This invention deals with a more specific design of the inner enclosure with additional merits. For clarity, it is remarked that the inner enclosure is also commonly referred to as the inner lining for a carrying case. SUMMARY OF INVENTION [0009] The current invention is conceived to realize a more specific design of the inner enclosure, or the inner lining for a carrying case, of an external data storage device with additional merits. Specifically, it is an objective of this invention to provide an inner enclosure for an external data storage device whereby the function of shock protection for the data storage device is achieved by using a minimum amount of materials thus saving manufacturing cost and reducing the associated product weight. [0010] It is another objective of this invention to provide an inner enclosure for an external data storage device whereby improved heat dissipation for the data storage device is achieved by using a minimum amount of materials thus saving manufacturing cost and reducing the associated product weight. [0011] A third objective of this invention is to provide an inner enclosure for an external data storage device whereby the functions of fire retardation, shielding against radio frequency interference and prevention of build up of static electricity are achieved with a selection of specific materials for the inner enclosure. [0012] Accordingly, the invention disclose a new design of the inner enclosure for the carrying case of, but without limitation to, an external data storage device as mentioned in the said prior application. The inner enclosure is made of a soft shock absorbing material and provides for a snug fit and an all around shock protection for the enclosed data storage device in both non-operating and operating modes. The inner enclosure consists of a device compartment and a removable cover. Once the inner enclosure is completely closed within an outer enclosure, the inner enclosure will provide a snug fit to the enclosed device all around. For good shock absorption while using a minimum amount of material, the inner surface of the inner enclosure is constructed with an array of substantially evenly spaced miniature columns called Micro Shock Absorber (MSA). In addition to shock protection, the MSA also provides air circulation to the enclosed storage device by creating a thin air space between the device and the inner enclosure. As needed, the material of the inner enclosure can be selected to be fire retardant, shielding against radio frequency interference, preventing build up of static electricity, allowing better heat dissipation from the data storage device while preventing dirt penetration into the interior of the enclosure. BRIEF DESCRIPTION OF DRAWINGS [0013] The invention is explained in full detail with the following detailed description of the preferred embodiments, with reference made to the accompanying drawings, wherein: [0014] [0014]FIG. 1 is one perspective illustration of a commonly practiced prior art wherein two rigid covers with mounting means are employed to enclose a storage device; [0015] [0015]FIG. 2 is one more perspective illustration of a commonly practiced prior art wherein two rigid covers with mounting means are employed to enclose a storage device; [0016] FIGS. 3 A-C are perspective illustrations of the current invention wherein two soft inner enclosures, or alternatively called inner linings, are employed to enclose a storage device; [0017] [0017]FIG. 4 is a perspective illustration of the current invention wherein the details of the MSA structure and its associated design parameters are shown; [0018] FIGS. 5 A-B are comparison of the wall structure between a traditional and the current design of the inner enclosure with design parameters illustrating the benefit of materials saving with the current invention; [0019] [0019]FIG. 6 illustrates an additional embodiment of the current invention wherein a set of micro venting slots are added to the wall structure of the current invention with MSA for further improved heat dissipation; [0020] FIGS. 7 A-B are additional perspective illustrations of the current invention wherein a fully enclosed storage device, within two soft inner enclosures with MSA, similar to that illustrated in FIG. 3C is progressively shown to be loaded into a soft outside enclosure; and [0021] FIGS. 8 A-B are the final perspective illustrations of the current invention wherein the fully enclosed storage device from FIG. 7B is progressively shown to be fully enclosed with the closure of a soft device cover and a soft connector cover. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0022] [0022]FIG. 1 and FIG. 2 are perspective illustrations of a commonly practiced prior art wherein two rigid covers with mounting means are employed to enclose a storage device. FIG. 1 illustrates, with two arrows, the progressive enclosure of a storage device 1 with a storage device interface connector 2 and an associated rigid connector interchanger 70 . The wall material of the storage device 1 is usually made of metal to house the precision mechanism inside. The storage device interface connector 2 , when hooked up, through the associated rigid connector interchanger 70 , with the corresponding mating connector of a computer not shown here, would provide all the necessary electrical power and interface signals to insure proper operation of the storage device 1 . As shown, the storage device 1 will generally be housed between a rigid top cover 30 and a rigid bottom cover 40 with a set of mounting screws 50 . The finished product is illustrated in FIG. 2. Usually these rigid covers are made of plastics or metal. Thus, the enclosed storage device 1 is still very susceptible to shock damage as the rigid covers do not provide any damping protection against shock. [0023] [0023]FIG. 3A, FIG. 3B and FIG. 3C are perspective illustrations of the current invention wherein two soft inner enclosures, or alternatively called inner linings, are employed to enclose a storage device. The two soft inner enclosures are, as shown in FIG. 3A, a soft top inner enclosure 3 and a soft bottom inner enclosure 4 . The storage device to be enclosed by the soft top inner enclosure 3 and the soft bottom inner enclosure 4 is the storage device 1 with a storage device interface connector 2 . The storage device interface connector 2 , when hooked up with the corresponding mating connector from a computer not shown here, would provide all the necessary electrical power and interface signals to insure proper operation of the storage device 1 . Many storage device 1 , such as external or portable hard drives, optical storage devices or computers with built in magnetic and optical storage devices, can be easily damaged when it is dropped accidentally. Thus, the soft top inner enclosure 3 and the soft bottom inner enclosure 4 are used together to provide protection for the storage device 1 in both operating and non-operating modes. The soft top inner enclosure 3 consists of a soft top inner enclosure base 9 c whose inside surface has a set of soft top enclosure MSA 17 which will be described in more detail later. The soft bottom inner enclosure 4 consists of a soft bottom inner enclosure base 9 a , four soft bottom inner enclosure side walls 9 d with a connector access slot 9 b located on one of the soft bottom inner enclosure side walls 9 d . Like the soft top inner enclosure 3 , the soft bottom inner enclosure base 9 a also has a set of soft bottom enclosure MSA 16 located on its inside surface which will also be described in more detail later. Thus, following the direction of the arrows, the soft top inner enclosure 3 and the soft bottom inner enclosure 4 will provide a snug fit to the enclosed storage device 1 all around except for the mechanical accessibility to the storage device interface connector 2 through the connector access slot 9 b of the soft bottom inner enclosure 4 . This is illustrated in FIG. 3B and FIG. 3C. [0024] [0024]FIG. 4 shows more details of the soft top inner enclosure 3 and the soft bottom inner enclosure 4 . To provide for sufficient shock protection with the proper range of softness, or durometer, the selected material for the inner enclosure is soft Microcellular Urethane (trade name: PORON), Polyurethane or other material with similar properties. For further enhancement of shock protection, the inside surfaces of both inner enclosures 3 and 4 are constructed with a set of substantially evenly spaced small columns of MSA protrusions. These are soft top enclosure MSA 17 for the soft top inner enclosure 3 and the soft bottom enclosure MSA 16 for the soft bottom inner enclosure 4 . As the MSA and the inner enclosure body are made of the same material, the MSA can be easily casted or molded as part of the enclosure in volume production. Furthermore, as neither the MSA nor the inner enclosure body requires high dimensional accuracy, the need of expensive tooling for the cast or mold is eliminated. [0025] The amount of shock protection provided by the MSA depends primarily on the following parameters: the durometer of the Microcellular Urethane, the MSA base thickness T, the MSA diameter D, the MSA height H, the MSA pitch P as well as the density of the enclosed storage device 1 . In general, the following qualitative design guidelines were discovered: (1) lower durometer of the inner enclosure base material yields higher shock protection; (2) higher MSA base thickness T yields higher shock protection; (3) larger MSA diameter D yields higher shock protection; (4) larger MSA height H yields higher shock protection; (5) lower MSA pitch P yields higher shock protection and (6) lower density of the enclosed storage device 1 allows higher shock protection. [0026] However, in practice, the complexity of the involved quantitative functional relationship amongst the above design parameters is found to be too complicated to warrant a mathematical treatment. Instead, an empirical design must be reached through a set of parametric experiments following the above qualitative design guidelines. As a quantitative example of this invention, we have made the following findings. [0027] A typical 2.5 inch hard disk storage device can be adequately shock protected from a drop height of up to 4 feet onto a hard surface with an MSA structure of the following parametric design: (1) inner enclosure base material is Microcellular Urethane; (2) durometer of the inner enclosure base material is 30 durometer; (3) MSA base thickness T=6.4 mm; (4) MSA diameter D=7 mm; (5) MSA height H=4 mm height; (6) MSA pitch P=17 mm. [0028] Another point to be made here is that, given the aforementioned complexity of the functional relationship among the design parameters, multiple combinations within a range of parameters exist for the same desired shock protection. For example, in the above case, an MSA diameter D from 6 mm to 8 mm and an MSA height H from 4 mm to 5 mm would all produce similar shock protection. [0029] A subtle but important benefit of the current invention is illustrated in FIG. 5A and FIG. 5B. FIG. 5A represents a prior art inner enclosure wall structure 20 which is plain while FIG. 5B represents the current invention with the MSA wall structure 21 optimized for a minimum overall thickness of the MSA structure T+H, for a specified amount of shock protection. While the prior art inner enclosure wall structure 20 has the same overall wall thickness S=T+H as the current invention, it was found that the prior art design can not provide the specified amount of shock protection as does the current invention. The reason is that, upon impact of the enclosed storage device with an external object, the numerous soft bottom enclosure MSA 16 of the current invention act as an initial spacer during the first stage of the shock absorption process where most of the associated kinetic energy is dissipated. That is, only the soft bottom enclosure MSA 16 go through related geometric deformation to dissipate the kinetic energy while the enclosed storage device stays free of contact with the soft bottom inner enclosure base 9 a . While the storage device still contacts the soft bottom inner enclosure base 9 a during the second, or last, stage of the shock absorption process, by this time the remaining kinetic energy to be dissipated is significantly lower than its value during the first stage. In summary, given the same specified amount of shock protection and the same overall wall thickness, the net kinetic energy to be dissipated upon impact by the enclosed storage device with the current invention would be significantly less than that with a traditional prior art design. Or equivalently, given the same specified amount of shock protection, the current invention will provide a design which has a significantly less overall wall thickness than the traditional design. This translates into an advantage of size and weight reduction with the current invention. Furthermore, given the MSA structure, the net volume occupied by the shock absorbing material is significantly less than that enclosed in the overall wall thickness T+H, this translates into another advantage of weight reduction with the current invention. A third advantage of the current invention is that, upon closure of the soft top inner enclosure 3 and the soft bottom inner enclosure 4 , a thin air space is formed between the enclosed storage device 1 and the inner enclosure with MSA wall structure 21 . The thin air space thus provides the function of air circulation resulting in a more uniform distribution of heat from the storage device 1 for a more efficient heat dissipation to the outside ambient. [0030] [0030]FIG. 6 illustrates an additional embodiment of the current invention wherein the inner enclosure with MSA wall structure 21 has a set of substantially evenly spaced micro venting slots 22 cut through its wall to further improve heat dissipation to the outside ambient. Of course, the cross section of these venting features does not have to be a slot. For example, it can be a circle, an ellipse or any other shape as long as easy manufacturability is maintained. [0031] Finally, Microcellular Urethane, one of the selected material for the inner enclosure with MSA, possesses additional physical properties which are important or beneficial to the enclosed storage device. Microcellular Urethane has low memory effect, which is important for the preservation of the MSA geometry after long termed usage or storage of the storage device. Microcellular Urethane is reasonably heat conductive which helps the dissipation of heat from the storage device. It does not accumulate static electricity thus provides good ESD protection for the storage device. It is fire retardant with UL-approval for a safe product. It can be metallically coated to shield against EMI/RFI for reliable data transfer. [0032] [0032]FIG. 7A and FIG. 7B are additional perspective illustrations of the current invention wherein a storage device is fully enclosed with a set of soft inner enclosures, similar to that shown in FIG. 3C, the storage device is progressively shown to be loaded into a soft outside enclosure 8 . Following the direction of the arrows in FIG. 7A, the now enclosed storage device 1 is first loaded into the soft outside enclosure 8 . Afterwards, the storage device 1 , now enclosed in both inner and outer soft enclosures with shock protection, is shown in FIG. 7B. Notice that the mechanical accessibility to the interface pins of the storage device 1 is maintained through the corresponding connector access slot 9 b of the soft bottom inner enclosure 4 and the connector access slot 15 of the soft outside enclosure 8 . [0033] [0033]FIG. 8A and FIG. 8B are the final perspective illustrations of the current invention wherein the enclosed storage device 1 from FIG. 7B is progressively shown to be fully enclosed like a carrying bag in the non-operating state of the storage device 1 with the closure of a soft device cover and a soft connector cover. Following the right hand arrow of FIG. 8A, the soft outside enclosure device cover 12 will be closed with the movement of the zipper mechanism consisting of two soft outside enclosure zippers 10 and an outside enclosure zipper handle 11 . Finally, following the left hand arrow of FIG. 8A, the soft outside enclosure connector cover 13 will be closed with the mating of a velcro hook pad 14 a to a velcro loop pad 14 b . The final enclosure in the form of a carrying bag is illustrated in FIG. 8B. [0034] In summary, as illustrated above, a first advantage of the current invention is that, given the same specified amount of shock protection, the current invention provides an inner enclosure for a storage device whose overall wall thickness is significantly less than that of a traditional design. The net result is a size and weight reduction of the product. [0035] The second advantage of the current invention is that, with the MSA geometry, the net volume occupied by the shock absorbing material is significantly less than that enclosed within the overall wall thickness. This means additional cost and weight reduction of the product. [0036] A third advantage of the current invention is that a thin air space is formed between the enclosed storage device and the inner enclosure with the MSA wall structure. The thin air space thus provides the function of air circulation resulting in a more uniform distribution of heat from the storage device for a correspondingly more efficient heat dissipation to the outside ambient. [0037] A fourth advantage of the current invention is that a set of micro venting slots are provided on the MSA wall structure to further improve heat dissipation from the storage device to the outside ambient. [0038] A fifth advantage of the current invention is that the selected base material for the inner enclosure has a set of physical properties which result in the following benefits such as preservation of the MSA geometry after long termed usage or storage of the storage device; improved heat dissipation from the storage device; good ESD protection for the storage device; fire retardation with UL-approval and shielding against EMIRFI for reliable data transfer. [0039] In conclusion, an improved inner enclosure, or alternatively called inner lining, with MSA has been described for an external storage device providing shock protection, improved heat dissipation plus a set of additional functions while reducing the cost, size and weight of the product. The invention has been described using exemplary preferred embodiments. However, for those skilled in this field the preferred embodiments can be easily adapted and modified to suit additional applications without departing from the spirit and scope of this invention. Thus, it is to be understood that the scope of the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements based upon the same operating principle. The scope of the claims, therefore, should be accorded the broadest interpretations so as to encompass all such modifications and similar arrangements.

An improved soft inside enclosure for shock protection of a variety of external electronic and computer peripheral comprises a set of substantially evenly spaced small columns of Micro Shock Absorber (MSA) protrusions that are integrated on the inside surfaces of the soft inside enclosure. Additionally, the base wall of the MSA structure can include a set of micro venting features for the improvement of heat dissipation from the enclosed devices to the ambient. A number of specific candidate materials are also presented for the construction of the soft inside enclosure with the MSA structure. A method for the systematic and experimental determination of a specific design of the MSA structure based on its durometer, thickness, diameter, column height, and pitch are disclosed.

The invention is based on a priority application EP 07 301 171.0 which is hereby incorporated by reference. TECHNICAL FIELD The invention relates to a method for providing unequal error protection to data packets in a burst transmission system. Each burst comprises a data section and an error protection section. The data section of each burst comprises one or more data packets and the error protection section of each burst comprises error protection codes. The data packets are grouped based upon respective priority levels. The invention also relates to a burst transmission system for performing said method. BACKGROUND OF THE INVENTION An example for such a burst transmission system is the handheld enhancement of the DVB (Digital Video Broadcasting) system. The DVB-H enhancements to the DVB-T (Digital Video Broadcasting Terrestrial) specifications include a forward error correction computed across the data section of a burst. The forward error correction code is placed in the error protection section of the same burst over which data section the error protection code has been computed. An example of such forward error correction is implemented in DVB-H as well as DVB-SH. The DVB-H as well as the DVB-SH (DVB satellite to handheld) both implement the multi-protocol encapsulation. The multi-protocol encapsulation (MPE) encapsulates multiple types of data, especially IP (Internet Protocol) datagrams into the data section of a burst. DVB-H/SH also implements the MPE-FEC (Multi Protocol Encapsulation-Forward Error Correction). MPE-FEC is the link layer error protection of DVB-H and DVB-SH. MPE-FEC provides intra burst data protection. A MPE-FEC frame is a matrix of 255 columns and a variable number of rows, e. g. 256, 512, 768, or 1024. Each element in the matrix of the MPE-FEC frame represents a byte. An MPE-FEC frame is an example of a burst. The first 191 columns of the MPE-FEC contain the IP datagrams that will be transmitted. This portion is the data section of the burst and is also called application data table (ADT). The rest of the 64 columns are dedicated to the forward error correction (FEC) generated by for example an eraser code, such as Reed Solomon, LDPC (Low Density Parity Check Code), etc. The FEC is contained in the error protection section of the burst. The FEC is also called RSDT (Reed Solomon Data Table) or inner-FEC. The inner-FEC is computed over the rows of the metrics ADT. It involves 1 D error correction, which is for example a FEC computed on each row of the ADT metrics. The redundancy created by the inner-FEC protects the loss of one datagram in one burst. Thus, the inner-FEC can insure an intra burst protection. In a wireless network, such as DVB-H, DVB-SH, WiMAX (Worldwide Interoperability for Microwave Access), 3G/LTE (3rd Generation Long Term Evolution), end users have different requirements in terms of latency video visual quality, processing capabilities and power. It is thus a challenge especially for broadcast services to design a delivery mechanism that not only achieves efficiency in network bandwidth but also meets the heterogeneous requirement and capacities of the end users. To address the above challengers the different quality of service requirements in all components of a media delivery system from end to end should be supported simultaneously. Examples of such media delivery systems are voice service, http services etc. Another example of such a media delivery system is a video delivery system which transmits scalable encoded video. Scalable video encoding is an advantageous way to meet the needs to achieve efficiency in network bandwidth and also to meet the heterogeneous requirement and capacities of the end users. In scalable video coding the signal is separated into multiple layers. The layers have different priorities. The base layer is the layer of highest priority. It can be independently decoded and provides basic video quality. The base layer must be robust to be received by users over all the network, what ever the radio conditions or the radio link quality might be. The enhancement layers can only be decoded together with the base layer and further increase the video quality and/or the video basic special and temporal resolution. The base layer in connection with the enhancement layer or enhancement layers provide video with the enhanced quality. Each terminal decodes at least the base layer and a number of enhancement layers that is linked to the capabilities of the terminal. Using scalable video layers allows networks providing multimedia broadcast and multicast services to adapt efficiently to the variability of the radio conditions, e. g. variable carrier to interference ratio or signal to noise ratio. It allows to optimise the usage of the radio resources using modulation and coding schemes leading to higher spectrum efficiency. Terminals experiencing bad radio link quality for example decode only the base layer, e. g. typically users at the edge of a cell for example. The base layer must be enough robust to be received by users all over the network or cell what ever the radio conditions or the radio link quality are. This can be achieved by choosing an adequate modulation and coding scheme. The enhancement layers are decoded only even the radio link quality is good, e. g. typically users near the antenna. The enhancement layer or the enhancement layers are differently protected than the base layer. They are usually less protected than a base layer e. g. by using a less robust modulation and coding scheme but leading to higher radio data rate. In the document “Multi burst sliding encoding (MBSE)” of Luc Ottavj, Antoine Clerget, Amine Ismail, which was presented during a technical working group within the DVB-SSP (DVB satellite service to portable devices) standardization, an outer-FEC algorithm is presented which extends the intra-burst protection to an inter-burst protection, so that complete burst losses may be recovered. In order to achieve this, data coming from several bursts are interleaved before FEC protection is applied. In the US patent application 2006/0262810 A1 a method for providing error protection to data packets in a burst transmission system is described. Error protection is provided unequally with respect to priority levels of the data packets. The error protection provided is inserted within one burst, thus protecting the loss of one data packet in one burst. The unequal error protection provided calculates the error protection code over the data section of one burst and puts the calculated error code in the error protection section of said same burst. The object of the invention is to provide a method for providing unequal error protection to data packets in a burst transmission system with extended protection. Another object of the invention is to provide a burst transmission system with unequal error protection for data packets with extended protection. SUMMARY OF THE INVENTION These objects and other objects are solved by the features of the independent claims. Features of preferred embodiments of the invention are found in the dependent claims. The invention provides a method for providing unequal error protection to data packets in a burst transmission system e. g. DVB-H or DVB-SH system. Each burst comprises a data section and an error protection section. The data section of each burst comprises one or more data packets and the error protection section of each burst comprises error protection codes. The data packets to be transmitted are grouped based upon respective priority levels, e. g. different layers of e. g. coded video data or other layered coded media data. The error protection provided to each group of data packets is based upon the respective priority level of the data packets. The error protection is provided by error protection codes contained in the error protection section of the bursts. The error protection codes for each group of data packets are created using data of data packets of said group which are contained in the data section of two or more bursts forming a first set of bursts. This means that error codes are computed using data of data packets belonging to the group of data packets which are contained in two or more bursts. The created error protection codes are then transmitted in the error protection section of one or more bursts forming a second set of bursts. The present invention extends the error protection over more than one burst. This enables recovery of consecutive bursts loss. It is adapted to media having long interruptions or fade outs, e. g. by a number of obstacles that may be responsible for a complete interruption of the signal of several seconds with the direct satellite link to a mobile phone. According to a preferred embodiment of the invention the first set of bursts is disjoint from the second set of bursts. This ensures that the data from which the error codes are computed is contained in completely different bursts from the bursts in which the error codes are contained. The second set of bursts may follow immediately the first set of bursts in this embodiment. This enables rapid recovery of bursts when there has been a fade out in the transmission connection. According to another preferred embodiment of the invention the first set of bursts has a non-empty intersection with the second set of bursts, i. e. the first set of bursts overlaps with the second set of bursts. This means that the error codes generated over the data sections of the first set of bursts are contained in the error protection section of bursts which are possibly also part of the first set of bursts. This ensures a faster recovery possibility after a fate out in the transmission connection. The unequal error protection is preferably achieved by using different numbers of bursts contained in the first set of bursts for different groups of data packets. Data packets within one group belong to the same priority level. For different priority levels the error protection codes are generated over a different number of bursts. This allows to balance the required security level of protection and the generated redundancy according to different priorities. According to a preferred embodiment of the invention the second set of bursts used for transmitting the error protection codes for a group of data packets of a higher priority contains a higher number of bursts in the second set of bursts used for transmitting the error protection codes for a group of data packets of lower priority. This allows to spread the error protection codes over more bursts for higher priority data packets. This allows for balancing required error protection and overhead. According to a preferred embodiment of the invention the groups of data packets correspond to layers of layered encoded data, e. g. layered encoded video data. Layered encoded video data is also known as scalable video. Scalable video can be seen as multiple, e. g. two or more hierarchical additive layers. This can be for example a basic layer providing a basic video quality and one or more enhancement layers providing finer quality improvements. The basic layer then corresponds to the highest priority layer. Packets of the basic layer of the video data are packets with the highest priority level. The data packets of the enhancement layers are of lower priority. The invention also concerns a burst transmission system, in particular a wireless burst transmission system such as a DVB-H or DVB-SH system. Each burst within said burst transmission system comprises a data section and an error protection section. The data section of each burst comprises one or more data packets and the error protection section of each burst comprises error protection codes. The data packets are grouped based upon respective priority levels and unequal error protection is provided to each group of data packets based upon the respective priority level. The error protection is provided by said error protection codes contained in the error protection section of the bursts. The burst transmission system comprises means for creating the error protecting codes for each group of data packets using data of data packets of said group which are contained in the data section of two or more bursts performing a first set of bursts. The burst transmission system further comprises means for transmitting the created error protection codes in the error protection section of one or more bursts performing a second set of bursts. This allows for an error protection extending beyond one burst. According to a preferred embodiment of the burst transmission system the unequal error protection is provided to groups of data packets which correspond to layers of layered encoded video data. BRIEF DESCRIPTION OF THE DRAWINGS Other characteristics and advantages of the invention will become apparent in the following detailed description of preferred embodiments of the invention illustrated by the accompanying drawings given by way of non-limiting illustrations. FIG. 1 shows a schematic overview over one burst, FIG. 2 shows a schematic overview over a first set of bursts and a second set of bursts, FIG. 3 shows an overview over a first set of bursts and a second set of bursts, FIG. 4 shows an example of parameterization for error protection parameters, and FIGS. 5-7 show examples of unequal error protection. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 shows a schematic overview of a burst 10 comprising a data section 20 and an error protection section 30 . Comprised in the error protection section 30 are error protection codes for protecting intra burst loss and protection codes for protecting against losses extending over more than one burst. Intra burst error protection is for example done by MPE-FEC in the case of DVB-H or DVB-SH. In the case of layered video transmission, the layers of unequal importance of a scalable video scheme should advantageously lead to an unequal error protection policy within the network. The unequal error protection according to the invention is provided by applying the extra burst error protection as shown for example in FIG. 2 according to priority levels of groups of data packets. FIG. 2 shows an example of extra burst error protection for a group of data packets. Extra burst error protection extends the error protection beyond the borders of one single burst. Shown in FIG. 2 are bursts 10 each comprising a data section 20 and an error protection section 30 . Error protection for data packets belonging to a group of data packets of the same priority level is provided by calculating error protection codes using data of data packets of bursts contained in a first set of bursts 50 . The calculated error protection codes are transmitted in the error protection section 30 of bursts 10 belonging to a second set of bursts 60 . In the example shown in FIG. 2 the first set of bursts 50 is disjoint from the second set of bursts 60 . A second set of bursts 60 follows the first set of bursts 50 in time. The error protection sections 30 of the bursts 10 also contain error protection codes for protecting intra burst losses. These error protection codes for protecting against intra burst losses are calculated over data contained in the data section 20 of the same burst 10 . FIG. 3 shows an example of extra burst error protection where the first set of bursts 55 has a non-empty intersection with the second set of bursts 65 . The example shown in FIG. 3 also provides error protection for a group of data packets belonging to the same priority level. As for the example of FIG. 2 unequal error protection for groups of data packets of different priority levels can be provided by varying the number of bursts contained in the first set of bursts 50 , 55 and the second set of bursts 60 , 65 . In the example shown in FIG. 3 extra burst error protection is provided by calculating error protection codes over data contained in the bursts 10 of a first set of bursts 55 . Those calculated error codes are transmitted in the error protection section 30 of a group of bursts 10 of a second set of bursts 65 . The first set of bursts 55 overlaps with a second set of bursts 65 . The quality degradation in a video transmission over radio compared to a perfect transmission is mainly determined by the packet lost behaviour observed at the video decoder. The propagation channel presents many impairments, e. g. deep fading, shadowing, etc., leading to a bursty packet loss. If one packet is lost it is very likely that consecutive packets will also be lost. In order to offer the video service to all the terminals in the cellular broadcast network, the base layer of video must be protected more than the enhancement layers, as the enhancement layers have less importance to the video decoding. The base layer can therefore be protected more by calculating more redundancy in the inner forward error correction codes. Inner forward error correction means that intra burst loss of a packet is protected by the error codes in the error correction section of said same burst. In the case of shadowing or deep fading for example a whole burst can be lost so. This would mean that the video service would be interrupted. The presented inventive method resolves this problem by the extra burst forward error correction. The extra burst error correction can be advantageously coupled to the inner burst error correction. The intra burst error correction is computed on the number N of the rows of a burst. The intra burst error correction is characterised by its rate equalling M/(M+K). In this equation M denotes the number of columns in the data section of the burst K denotes the number of columns in the error protection section of the burst. The extra burst error correction computed from the columns of successive bursts leads to a rate equalling C/(C+S). The parameter C gives the number of successive bursts, C contained in the first set of bursts 50 or 55 . The parameter S gives the number of bursts on which the extra burst error correction codes are spread. S is the number of bursts contained in the second set of bursts 60 or 65 . In global this gives the coding rate of inner protection coding rate plus extra burst protection coding rate. The global coding rate is the sum of the intra burst protection coding rate plus the extra burst protection coding rate. The parameters K, C, and S must be well chosen to keep the global protection coding rate at an acceptable level. The invention focuses on varying the rate of coding of the extra burst error protection to ensure a high protection for the base layer and to keep a good bandwidth efficiency. Thus K is kept fixed for the following examples. Of course K can be varied in order to further increase the protection for the base layer. The variation of K can be advantageously combined with the variation of C and S. The rate of extra burst error protection can be denoted by α. α is then given by C/(C+S). This can be transformed to S=(1/α−1)C. In FIG. 4 are shown three lines of possible parameter choices. Assuming that there is one base layer the extra burst error protection coding rate is given by α B . Assuming that there are two enhancements layers E 2 and E 1 the extra burst error protection coding rates are given by α E2 and α E1 . The lines with the corresponding angle α B , α E1 or α E2 give the parameter choices sets for possible parameter combinations of S and C for the respective layers. In FIG. 4 the different curve of variations of S depending on the value of C are plotted. There is an infinity of solutions to fix the values of C and S. The choice of the values for C and S will advantageously be done by the operator of the telecommunication network or the operator of the service provider, e. g. the video service provider. In general the protection is higher when the parameter α is lower. This is the reason why the parameter α B shown in FIG. 4 is larger than the parameter α E1 for the first enhancement layer and larger than the parameter α E2 for the second enhancement layer E 2 as shown in FIG. 4 . In FIGS. 5 , 6 , and 7 examples of three extra burst protection schemes are given. For a given C (C fixed) increasing S leads to a lower α. A lower α leads to a higher protection. Allowed value of S allows thus to obtain more redundancy. The first example of a scheme shown in FIG. 3 therefore spreads the error protection codes generated from the basic flow B over a higher burst number S then the protection codes generated from the enhancement flow E. C is kept constant. In this case the protection inequality lays in the redundancy quantity. It is shown in FIG. 5 that for the basic layer B the first set of bursts 50 .B comprises four bursts. The first set of bursts for the enhancement layer E 50 .E comprises also four bursts. The parameter C is thus kept constant. The second set of bursts for the base layer 60 .B contains two bursts. The second set of bursts 60 .E for the enhancement layer contains only one burst. Redundancy is thus increased by using a higher number of bursts for the second set of bursts 60 .B for the base layer than for the second set of bursts 60 .E for the enhancement layer. For the example given in FIG. 6 the parameter S is kept fixed. Increasing C thus leads to a higher value of α. The extra burst error protection protects less in this case. Indeed, the ratio of the redundancy quantity to the data quantity decreases which leads to the diminution of the correction capacity of the error correction. Thus, the example given in FIG. 6 uses a lower number of successive bursts C for generating the error correction code in the basic flow case than in the enhancement flow case. The number of bursts contained in the second set of bursts 60 .B and 60 .E is equal to 2 for both basic layer and the enhancement layer in FIG. 6 . The parameter S is thus equal to 2 for the example given in FIG. 6 . The number of bursts contained in the first set of bursts 50 .B for the basic layer is 2 for the example given in FIG. 6 . The number of bursts contained in the first set of bursts 50 .E for the enhancement layer is equal to 4 for the example given in FIG. 6 . However, in the scheme given in FIG. 6 the protection against the lost burst recovery of the base layer is dramatically reduced. Indeed, the lower the value for the parameter C, which is the number of bursts contained in the first set of bursts, the number of bursts recovered when lost is reduced. For this reason the value for the parameter C should be increased to enable a terminal to receive the base layer even in a presence of large shadowing and deep fading, as is the case for example when the terminal is located under a bridge. In order to keep some correction capacity for large C values S must be increased as well. This leads to a third example of extra burst error correction as shown in FIG. 7 . The example shown in FIG. 7 uses a higher number of successive bursts C for generating the error correction code on the base flow than in the enhancement flow case. As shown in FIG. 7 the first set of bursts 50 .B for the base layer comprises 4 bursts. The first set of bursts 50 .E for the enhancement layer comprises 3 bursts. The value for S is different for both flow types as well. It is adapted to the values for the parameters C in order to keep a good correction capacity for the base layer B. The value for S is 1 for the second set of bursts 60 .E for the enhancement layer. The number of bursts contained in the second set of bursts for the basic layer 60 .B is 2. All the examples given above lead to an unequal error protection for different priority groups of media data, e. g. different layers of video and data providing an extra burst error correction.

The present invention relates to a method for providing an equal error protection to data packets in a burst transmission system. The data packets are grouped based upon respective priority levels and error protection is provided to each group of data packets based upon the respective priority level. The error protection codes for each group of data packets depending on the respective priority level is created using data of data packets of the group which are contained in the data section ( 20 ) of two or more bursts ( 10 ) forming a first set of bursts ( 50, 50 .B, 50 .E, 55 ) and the created error protection codes are transmitted in the error protection section ( 30 ) of one or more bursts ( 10 ) forming a second set of bursts ( 60, 60 .B, 60 .E, 65 ). The invention further relates to a burst transmission system for performing said method.

BACKGROUND OF THE INVENTION This invention relates to a method of manufacturing reinforced insulating panels, and particularly to a method of making reinforced insulating panels impregnated with thermosetting resin, which utilize glass fiber reinforced material provided in a three-dimensional construction, wherein the delamination between surface material and insulating material is minimized and wherein the mechanical durability thereof is great. A conventional reinforced panel of aluminum-insulating material is shown in FIG. 1, and is used as carrying boxes on refrigerator vehicles or containers and comprise an insulating member 101 and aluminum panels 102 fixed to both faces of the insulating member 101. Containers for marine transportation made of such panels are likely to corrode at their surface materials due to seawater and sea wind. When applying such panels to refrigerator containers or carrying boxes of refrigerator vehicles, such containers and boxes suffer from vertically acting compression and severe buckling load. When joining surface member and insulating member, e.g., urethane foam of simple laminated structure, insulating members are likely to isolate or break at the interfaces thereof, resulting in the loss of refrigerating and freezing-retaining properties, which shortens the lives of carrying boxes or refrigerator containers. SUMMARY OF THE INVENTION An object of this invention is to provide a reinforced insulating panel which has great mechanical endurance properties and remarkably represses or prevents the delamination between surface members and insulating members. Another object of this invention is to provide a method of making a reinforced insulating panel which is of three-dimensional construction comprising insulating members and glass fiber textiles impregnated with thermosetting resin. The reinforced insulating panel according to this invention is made by covering inner covering of glass fiber textiles with urethane foam of regular size, quilting the inner covering and urethane together, covering the quilted member with an outer covering of glass fiber textiles, and impregnating the outer-covered member with thermosetting resin and hardening the impregnated member. Still another object of this invention is to provide a method of making a reinforced insulating panel comprising the steps of equalizing the length of urethane foam of regular size and glass fiber textiles, quilting the same-length members together so as to constitute reinforced members, providing partitioning members between the reinforced members, covering the surface of the reinforced members, and partitioning members with glass fiber textiles, impregnating the surface-covered member with thermosetting resin and hardening the impregnated member. As partitioning members, partitioning panels of FRP are inserted. Alternatively, a single inner covering of glass fiber textiles longer than the insulating member is provided for covering the insulating member in the c-shape. The insulating member and single inner covering are quilted together for having vertical parts of the inner covering serving as partitioning members between the reinforced members. Alternatively, upper and lower inner coverings of glass fiber textiles are provided, the edges of each inner covering being longer than the thickness of the insulating member by half. The margin parts of the edges are bent and fixed to the end faces of the insulating members thereby forming partitioning members. The reinforced insulating panels of I-beam construction of this invention are obtained by any one of the above-described methods. BRIEF DESCRIPTION OF THE DRAWINGS Further features and details of the invention will be apparent from the following description of the embodiments which are given with reference to the accompanying drawings, in which: FIG. 1 is a sectional view of the conventional aluminum insulating panel; FIG. 2 is a perspective view of one embodiment of first molded goods of reinforced insulating panel of the present invention; FIG. 3 is a plan view of FIG. 2; FIG. 4 is a sectional view of a finished reinforced insulating panel; FIG. 5A is a perspective view of a middle member of one embodiment of this invention; FIG. 5B is a perspective view of a middle member of another embodiment of this invention; and FIGS. 6A, 6B and 6C illustrate the reinforced insulating panels of the present invention having several kinds of partitioning members. DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIGS. 2 to 4, an inner covering of glass fiber textiles 2 covers both sides of an insulating panel 1 of urethane foam, or the like. The insulating panel 1 of regular shape and inner covering of glass fiber textiles 2 are quilted together by reinforcing fiber thread 3. The inner covering of glass fiber textiles 2, insulating panel 1 and reinforcing fiber thread 3 constitute a middle member (a). The middle member (a) has a three-dimensional construction. The material of the inner covering of glass fiber textiles 2 is roving fiber. The reinforcing fiber thread is made by glass fiber, carbon fiber or aramid fiber. The thickness and density of the reinforcing fiber thread 3 depends on the use of insulating panel 1. Each inner covering of glass fiber textiles 2 of the middle member (a) is enclosed by an outer covering of glass fiber 4 and then impregnated with thermosetting resin for fire retardancy. Thereby, reinforcing fiber thread 3, which has been exposed outside of the inner covering of glass fiber textiles 2 and thus has been in an unstable state, is in fixed position. The inner and outer coverings are made of one-direction or plain cloth. The thermosetting resin is unsaturated polyester resin, epoxy resin or melamine resin and is thereby fire retardant. The condition of hardening depends on the kind of resins and the use of the insulating panel. Thermosetting resin is used in the shape of prepeg which is made by pre-saturation of outer glass fiber 4. Otherwise, the thermosetting resin is produced by pouring liquid thermosetting resin into the reinforcing material and hardening the reinforcing material. The resin saturating process influences the durability and mechanical strength of the finished insulating panel. Therefore, during the process, molding should be achieved as close as possible so as not to produce pores. As shown in FIG. 6A, the middle members (a) obtained are arranged in a line. FRP partitioning members 5 are inserted between the middle members (a). An outer covering of glass fiber 4 encloses the middle member (a) and the partitioning member 5. Then, the enclosed middle member (a) is impregnated in the fire retardant thermosetting resin and hardened, thus producing the reinforcing material. As described above, when using FRP partitioning members 5 as the partitioning member, the I-beam construction formed when molding FRP causes an increase in compressive load with respect to the horizontal direction of the panel face. Furthermore, when an external force acts in the vertical direction, the bending strength increases, causing deformation of the insulating reinforcing panel to decrease remarkably. As shown in FIG. 5A, an inner covering of glass fiber textiles 2 is larger than an insulating panel 1 of urethane foam, or the like, and encloses the insulating panel 1 in the U-shape. That is, the inner covering of glass fiber textiles is longer than one face of the insulating panel 1. A reinforcing fiber thread 3 quilts the insulating panel 1 and the inner face of glass fiber textiles 2, thus forming integral margin members 2a. The integral margin members 2a serve as partitioning members. The members 1, 2, 3 and 2a constitute a middle member (a'). As shown in FIG. 6B, the middle members (a') are arranged in a line as follows. The back of one of the middle members (a') contacts an open face of the other middle member (a'). Outer coverings of glass fiber 4 enclose the upper and lower faces of the middle members (a'). Then, the enclosed middle members (a') are impregnated with thermosetting resin and hardened, thereby producing a deformed reinforcing material. As shown in FIG. 5B, upper and lower inner coverings of glass fiber textiles 2 are larger than the insulating panel 1 of urethane foam, or the like (2) and enclose the insulating panel 1 in the shape of U and inversed U. That is, the upper and lower glass fiber inner covering of glass 2 enclose approximately half of the one face of the insulating panel 1. The insulating panel 1 and the upper and lower coverings of glass fiber textiles 2 are quilted together by reinforcing fiber thread 3. Separable margin parts 2b serve as the partitioning member. The members 2b, 1, 2 and 3 constitute middle members (a"). As shown in FIG. 6c, the middle members (a") are arranged in a line and are enclosed by outer coverings of glass fiber 4. The enclosed middle members (a") are impregnated with fire retardant thermosetting resin and hardened. Thus, a deformed reinforcing material in accordance with a second embodiment is obtained. Regardless of what methods are chosen, glass fiber textiles and reinforcing textile thread which have passed the hardening process serve as an excellent FRP. Furthermore, resin may be impregnated into the glass fiber textiles by capillary action and hardened. Therefore, each strand of fiber becomes a kind of FRP bar. According to a bending test, when thickness of the covering was about 1.5-2.0 t when using textiles having the same property as leather, the strength was more than two times that of insulating panels having no partitioning members and the deformation decreases by less than 1/2 when compared with insulating panels having no partitioning members. The insulation-reinforcing panels of this invention are reinforced in a three-dimensional way and have a unitary construction. Therefore, the insulation-reinforcing panels of this invention sufficiently endure continuous compression and withstand buckling. Furthermore, the insulation-reinforcing panels of this invention generally are capable of absorbing shock. Therefore, the panels have excellent anti-shock properties. The conventional aluminum/urethane foam containers, when used for sealift, are susceptible to corrosion by seawater. However, when applying the insulation-reinforcing panel of three-dimensional construction to containers, or the like, such containers are not likely to corrode as a result of seawater and their mechanical life increases. Furthermore, the weight of such containers decreases by 20%. In addition, the reinforced insulation panel of this invention is reinforced by reinforcing material, e.g., glass fiber textiles, therefore, even if the reinforced insulating panel is cracked, the cracks do not spread. Therefore, the reinforced insulating panel of this invention has a much longer life than conventional insulating panels. FRP molding materials are easier to manufacture than general metal materials. The FRP molding materials are attached to metal panels with rivets, or the like. However, since the reinforced insulating panels are simultaneously impregnated with thermosetting resin, the joining strength is great, thus preventing delamination. Furthermore, the panels have a fluid blocking function wherein fluid cannot penetrate the inside of the panel. In addition, by providing partitioning members between the middle members, the compressive load in the horizontal direction of the panel face increases and the bending strength with respect to the external force acting in the vertical direction also increases. Therefore, the reinforced insulating panel is prevented from deforming. While the invention has been described in connection with the preferred embodiments, it will be understood that modifications thereof within the principles outlined above will be evident to those skilled in the art and thus the invention is not limited to the preferred embodiments but is intended to encompass such modification, within the scope of the appended claims.

A method of making a reinforced insulating panel which includes the steps of covering insulating material, such as urethane foam of a regular size with glass fiber textiles, quilting the insulating material and the glass fiber textiles together so as to produce an integral middle member, covering the inner covering of the glass fiber of the middle member with an outer covering of the glass fiber and impregnating the covered member with a thermosetting resin and hardening the impregnated member. The glass fiber reinforced panel produced has excellent fire retardant and water repelling properties, has improved compressive strength and does not deform or delaminate easily.

BACKGROUND OF THE INVENTION This invention relates to geothermal energy in general and more particularly to an improved method of extracting geothermal energy in a hot, dry rock system. With the shortage of petroleum products and high prices, there is great deal of interest in alternate sources of energy. One such source is geothermal energy. This energy is energy taken from the natural heat of the earth. Various systems have been developed for such purposes. Typical are those disclosed in U.S. Pat. Nos. 3,817,038, 3,786,868 and 3,911,638. In a hot dry rock system such as that disclosed in U.S. Pat. No. 3,817,038, an injection well and a production well are drilled and a fluid is injected into a geothermal area through the injection well, the fluid forced through the formation with simultaneous heating and the heated fluid then recovered from the production well. The recovered heated fluid is then used on the surface to generate energy. For example, the heated fluid may be expanded to steam and used to drive a steam turbine, the condensate from the steam turbine along with any makeup water then being reinjected in the injection well to form a closed system. Another approach similar to the one in which two wells are drilled is one in which a single well is completed with a dual casing string which permits injection of cold water at the bottom of the fracture system and recovery of hot water at the top of the fracture. A third approach, which is known as "huff and puff", is one in which the well is operated in a pulsed mode where water is alternately pumped into the fracture, allowed to heat up and then withdrawn. Operation of several wells of this type in sequence provides power for sustained operation. The pulsed mode operation has the additional virtue of permitting use for load following applications, i.e., for driving a generator which follows the electrical demand load, pulsing can be controlled in dependence on the demand. Injection and production of water requires energy and any approach which diminishes the reinjection or production energy required, diminishes the cost of producing geothermal energy from this resource and increases the net amount of energy recovered from the resource reducing waste and increasing the net reserves of energy indigenous to the United States. SUMMARY OF THE INVENTION The present invention has as its object improving the efficiency of energy removal from hot rock geothermal systems. In accordance with the present invention, heat extraction from hot rock systems is accomplished in an advantageous manner by employing as a energy recovery fluid, a mixture of water and a calcium halide. In particular calcium chloride and calcium bromide may be used either separately or together. Calcium chloride has the ability to raise the specific gravity of the inflowing brine to the geothermal system to about 1.4 to 1.5 while the hot return brine will have specific gravities of only 1.0 or slightly less depending upon the termperature, pressure and content of water and any additional additives. Calcium bromide acts in similar fashion. As a result, a pressure gradient is developed which drives the circulation of the heat extracting fluid. In the pulsed mode case, the use of such a mixture serves to substantially reduce the amount of energy required to reject and recover the heat extraction fluid and as an additional benefit, reduces the energy required to fracture the hot rock, which is desirable, in that fractioning further increases heat recovery and efficiency by increasing the rock surface area available for heat transfer. The addition of a calcium halide to the energy recovery fluid of a hot dry rock geothermal energy recovery system, either the pulse or continuous injection/projection mode increases net system energy output by reducing the energy required for injecting the energy recovery fluid to the heat bearing formation due to the increased density imparted to the energy recovery fluid by the additive. Calcium halide additions further reduce the energy required for transporting the energy recovery fluid from the heat-bearing underground rock formation to the ground surface by virture of the reduced density imparted by the additive fluid while at elevated temperatures. Other materials may be added to the energy recovery fluid for other purposes. In particular materials having a high vapor pressure are helpful. An example of such a material is acetone. These materials serve to increase the hydraulic pressure of the hot fluid. In the pulse mode of heat extraction this increased pressure helps with growth of additional rock fractures that serve to provide more heat and the pressure also assists in driving the hot fluid back out of the well where it can be utilized. Acetone also reduces the ability of the mixture to dissolve minerals and diminish the suspension of colloidal solids thereby reducing the tendency of wells to scale, allowing more continuity in the recovery of energy and enhancing the economic desirability of what may have previously been considered uneconomic sources of energy. The use of acetone mixed with water for use as a fluid in such a system is described in applicant's copending Ser. No. 778,388 filed on even date herewith and entitled Improved Method for Energy Extraction From Hot Dry Rock Systems. BRIEF DESCRIPTION OF THE DRAWING The single FIGURE illustrates the type of system in which the heat extraction fluid of the present invention may be used. DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, in a hot rock geothermal system, for example, a system such as that shown in the aforementioned U.S. Pat. No. 3,817,038, a mixture of water and calcium chloride and/or calcium bromide is used as the heat extraction or energy recovery fluid. Such a system is shown in basic block diagram form on the FIGURE. Shown is a closed loop system containing the heat extraction fluid of the present invention. Fluid is initially supplied to the system and made up over a line 11. The line 11 connects with a line 13 which is the input to an injection well 15. The injection well is drilled down to the depth of the hot rock system and is collected in a production well 19. The output from the production well 19, which will be the fluid heated by the hot dry rock system 17, flows in a line 21 to a steam turbine 23 where it is expanded. The turbine is used to drive a driven member 25 such as a generator. The working fluid from the steam turbine, in the form of a vapor is exhausted over a line 25 to a condenser 27 where it is brought back into the liquid state. This liquid then flows through a line 29 to a pump 31 which pumps it back into the injection well 15. As noted above, the use of a closed loop with a condenser conserves the working fluid. Whatever losses are encountered can be made up by supplying make up fluid over the line 11. Preferably, this mixture also has added to it acetone. Calcium chloride is added in an amount to raise the specific gravity of the heat extraction fluid supplied into the well, for example, in an injection well, to 1.4 to 1.5 at a temperature of approximately 20° C. After injection into the well, due to a subsequent heating which takes place in the hot rock system, the specific gravity is reduced to 1.0 or slightly less depending on the amounts of the various materials present. This then results in a pressure gradient which aids in circulation of the heat extraction fluid through the well. Acetone will normally constitute 10 to 20% by weight of the heat extraction fluid. Calcium chloride and/or calcium bromide will constitute 1 to 50% of the heat extraction fluid with the remainder water, i.e., calcium halide can be added up to its limit of solubility. The heat extraction fluid ideal high vapor pressure additive most useful in the pulse mode of heat extraction depends on the climatic conditions at the generating site. For cases such as the Imperial Valley, when 130±° F. is the normal summer cooling water temperature, then the additive should have an atmospheric pressure boiling temperature below water (212±° F) but above 130° F so that it will be condensable with a water cooling system. Acetone appears to be the superior substance for these purposes, having a boiling point of 133.7° F. If lower heat rejection temperatures are feasible, other additives are possible. In general, compounds soluble in water are superior. These include methanol, ethanol, isopropanol, acetone, and dioxane. Actually, methane, ethane, propane, butane, isobutane, and methyl ethyl ketone have sufficient water solubility at high temperatures that they serve under special conditions as usable compounds. Ammonia in water is also a useable material subject to assurance of an economically acceptable low from the heat extraction fluid loss by ion exchange with the heat source host rocks. Furthermore, additional materials can be added to the heat extraction fluid mixture forming various admixtures to accomplish secondary functions which will not depart from the scope of this invention. Includes among these are additional organic liquids to change the thermodynamic properties of the heat extraciton fluid and complexing agents to complex and extract materials of economic interest. Those skilled in the art will see many modifications and applications of the method herein described without departing from the scope of this invention. An example of a group of compounds which could have limited application are the amines. Low molecular weight amines such as tri-methyl amine could serve directly as a heat extraction medium while higher molecular weight amines either as ionized salts or as undissociated species are usable to condition the rock surfaces to change wetability; to reduce ion exchange between the heat extraction fluid and the rocks; and to serve as corrosion inhibitors for equipment installed in the well system. As a secondary function, also the solution used as a heat extraction fluid can be used to leach the hot rock of desired metals without departing from the scope of this invention. Typical complexing agents range from compounds such as acetylacetonate to complex chelating agents. Others include mild oxidants such as ferric chloride and many others. The heat of the rock provides a considerable increase in ion exchange and reaction rates compared to ordinary leaching which takes place at or near surface temperatures. The addition of the aforementioned ferric chloride or other mild oxidant can be used to liberate metal sulphides and convert the sulphur to sulphate which would be left in the hot rock as calcium sulphate while the metal chloride stays in solution. The use of calcium chloride, water, and acetone as a heat extraction fluid gives rise to a number of phenomena that may to some degree cause problems if not handled correctly and also produce certain benefits if handled properly. The presence of concentrated calcium ion solutions will induce ion exchange with framework and layer silicate minerals such as feldspars and micas respectively. This has the effect of converting calcium chloride to sodium and potassium chloride. However, the use of acetone suppresses the solubility of sodium and potassium chloride so these may tend to precipitate out on the surface of the fractures and potentially cause some blockage. Occasional flushing with acetone-free or low acetone calcium chloride will serve to dissolve these salts which can then be recovered from the wash solution. One technique known to the art of a solution mining of underground salt deposits for selective potassium chloride recovery is to cool the brine. Potassium chloride will selectively precipitate and the sodium chloride stay in solution. This can be recovered either by evaporation concentration or, if acetone is present, by addition of more acetone which will salt out the sodium chloride. Alternatively, other techniques known to the art of solution mining consist of operation in a reducing environment can permit the use of complexing agents that would be unstable in an atmospheric environment. An example of such an agent is the polysulphide ion or the bisulphide ion which acts to solubilize metal sulphide minerals. Once the minerals which are desired to be extracted are dissolved in the brine, they can be extracted using conventional techniques ranging from temperature and pressure change, pH adjustment, hydrogen reduction, ion exchange, precipitation by sulphide ions, concentration by evaporation and selected solvent extraction without departing from the scope of this invention. The wash water above as well as the normal calcium chloride brine used as a heat extraction fluid is a potential feedstock for chemicals recovery by a number of different means. The selective ion exchange of calcium for potassium and potassium recovery by cooling has been noted. The process of converting calcium chloride to potassium chloride also causes an enrichment of bromide in the calcium chloride heat extraction fluid and occasional processing through an extraction loop involving oxydation with elemental chlorine followed by absorption provides a means of bromine recovery. Lithium builds up in the calcium chloride heat extraction fluid as a consequence of ion exchange and is also a potentially valuable product which may be recovered by pH increase effected by carbonation. Silica dissolves in the heat extraction fluid at high temperatures and precipitates out at low temperatures. This provides a means of producing a high surface area amorphous, hydrated highly reactive silica usable as a feedstock for producing sodium metasilicate and related compounds as well as an absorptive carrier for other materials such as water and insecticides. This material is usable, when dry, as a filler in plastics and elastomers. This process of processing the brine by cooling so as to precipitate the silica, serves to scavenge colloidal materials such as metal sulfides. This is a direct means of recovering gold, silver, and copper. The technique involves collecting the silica precipitate either in a settling pond, baffle device, or fluidized bed followed by crushing, roasting in air to oxydize the sulfide in the precipitate followed by leaching with solubilizing chemicals. These include either alkaline cyanide solutions or dilute nitric acid solutions. As noted above, the present invention relates to a type of geothermal system which is known as a dry, hot rock system. There is another type of geothermal system known as a hydrothermal brine system. These are wet systems in which heat is recovered from hot naturally existing brine. These brines sometimes contain large amount of calcium chloride and in operating such hydrothermal wells, calcium chloride is obtained as a by-product during solar evaporation of the brines. The present invention provides a use for this by-product of hydrothermal wells, i.e., introducing the calcium chloride into a hot dry rock system to recover thermal energy therefrom, thereby enhancing the economics of hydrothermal energy reserves. In summary, the present invention in one aspect comprises mixing calcium chloride with water to form a heat extraction fluid more efficient than those presently known to the art of hot dry rock geothermal wells which will produce an increased pressure gradient and reduce the amount of energy needed to operate the well thereby improving the thermal efficiency and economic viability of the hot dry rock energy recovery systems. Furthermore, various chemical agents have been noted which are known to the art of solution mining can be added to the disclosed heat extraction mixture to perform various functions and further improve the economic efficiency of the operation without departing from the scope of this invention. Finally, the manner in which the present invention permits using a by-product of hydrothermal systems as differentiated from hot dry rock systems to reduce the cost of energy extraction from hydrothermal systems has been described.

In order to extract energy in a matter more efficient than is presently known to the art, from hot dry rock geothermal systems, a mixture of water and calcium chloride is used. The fluid mixture is injected into a formation and forced through the formation with simultaneous extraction of heat from the energy recovery or heat extraction surrounding rocks. The fluid and a larger fraction of its contained energy are then recovered than can presently be recovered by technology known to the art.

This application is a continuation-in-part of application Ser. No. 661,160, filed Oct. 15, 1984, now abandoned. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a sealed lead-acid battery, and particularly to a sealed lead-acid battery which is sealed by utilizing what is called an "oxygen cycle," i.e., the action of causing the oxygen gas that is evolved at the positive plate toward the end of charging to react with a negative active material. 2. Description of Prior Art For a lead-acid battery to be sealed by the "oxygen cycle" the oxygen gas that is evolved toward the end of charging must be transported from the positive plates to the negative plates. In order to ensure this gas transport, a gelled electrolyte is used or absorption of the electrolyte by porous separators is adopted. Regarding the latter method, it has been recently reported that the porous separators are not completely filled with the electrolyte and voids for the transport of the oxygen gas from the positive plates to the negative plates are present in the porous separators. The idea of using these porous separators in the sealed lead-acid battery is disclosed, for example, in U.S. Pat. No. 3,862,861. It states that the sealed lead-acid battery disclosed in characterized in one aspect by the hypothesis that the porous separators have a higher capacity for absorption of electrolyte than the plates and the electrolyte within the plates is present in the form of a thin film wrapped around particles of active materials. According to this disclosure, it is inferred that the electrolyte is substantially present within the separators. With a view to improving the high rate discharge characteristics, this U.S. patent contemplates reducing the discharge current density by using thin flexible "non-self-supporting" grids. To preclude the "non-self-supporting" grids from shortening the battery service life, the plate assembly is wound under exceedingly high pressure. SUMMARY OF THE INVENTION The present inventors tried an another approach to the improvement in the high-rate discharge characteristic and service life. It has been widely known that the capacity of the sealed lead-acid battery of this type is generally affected by the concentration and amount of the electrolyte in the cell. It has been now found that the high-rate discharge characteristics is affected not only by the aforementioned concentration and amount of the electrolyte but also by its apportionment between the plates and separators of the plate assembly. For example, it has been demonstrated that, for the same concentration and the same amount of electrolyte to be added, the high-rate discharge characteristic are superior when the proportion of the electrolyte contained in the positive and negative plates is larger and the proportion in the porous separators is smaller than otherwise. This knowledge is partly described in JA-OS No. 87080/57, which was laid open for public inspection on May 31, 1982. In addition to this knowledge, it has been found that the pores of the positive and negative active material must be kept filled substantially with the electrolyte. An object of this invention is to provide a sealed lead-acid battery which has long service life and exhibits little degradation of the high-rate discharge characteristic due especially to repeated cycles of charging and discharging. Another object of this invention is to provide a sealed lead-acid battery which excels in ability to absorb O 2 gases and reproduce water during overcharging. A further object of this invention is to provide a sealed lead-acid battery which excels in ability to recover by charging after a long overdischarged-state storage. The other objects and characteristics of this invention will become apparent from the further disclosure of this invention to be made in the following detailed description of a preferred embodiment, with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing changes in distribution or amounts of electrolyte absorbed by positive plates, negative plates, and separators in the sealed lead-acid battery of this invention as caused by the change in the total amount of electrolyte added to the cell. FIG. 2 is a graph showing the relation between the amount of water-loss of electrolyte and the high-rate discharge characteristic in the sealed lead-acid battery of this invention. FIG. 3 is a graph showing the alternate charge and discharge cycle life of the sealed lead-acid battery of this invention. DESCRIPTION OF PREFERRED EMBODIMENT The present invention will be described in detail below with reference to a preferred embodiment of the invention. The paste for the positive plates was obtained by mixing 100 kg of fine lead oxide powder with an average particle diameter of about 4.5 μm and a specific surface are of about 1.40 m 2 /g as measured by the BET method (hereinafter all the values of specific surface areas are invariably those measured by the same method) with 20 liters of sulfuric acid with a specific gravity of 1.14 d. Positive plates were obtained by applying the paste on cast grids of a Pb-0.09% Ca and 0.55% Sn alloy with a thickness of 3.4 mm, curing and forming thereof under ordinary conditions. The positive plates measured 76 mm in width, 82 mm in height, and 3.4 mm in thickness and contained 60 g of active material. The positive active material had a specific surface area of about 3.5 m 2 /g and an average pore diameter of about 0.32 μm. The aforementioned lead oxide powder was mixed with the ordinary expanders and other additives. The paste for the negative plates was obtained by mixing 100 kg of the lead powder mixture with 15 liters of dilute sulfuric acid with a specific gravity of 1.12 d. Negative plates were produced by applying the paste on grids with the same alloy composition as that used in the grids for the positive plates of 76 mm in width, 82 mm in height, and 1.9 mm in thickness. The pasted negative plates were also cured and formed under ordinary conditions. The amount of the negative active material thus obtained weighed about 33 g per plate. The negative active material had a specific surface area of about 0.43 m 2 /g and an average pore diameter of about 1.0 μm. A separator was prepared in the form of a sheet having a width of 83 mm and height of 88 mm, which was made by entangling together 90 wt% glass fibers having a nominal fiber diameter of about 0.8 μm with 10 wt% glass fibers having a nominal fiber diameter of about 11 μm without any binder by the wet method. This separator had a weight of 160 g/m 2 , a specific surface area of about 1.45 m 2 /g, an average pore diameter of about 7 μm, and a true specific gravity of 2.5. A cell element was assembled by alternately superimposing three positive plates and four negative plates with the separators placed between them. The cell element with a thickness of 23.5 mm was inserted in an electric cell. In this case, each distance between the plates was 0.95 mm and the pressure exerted on each assembled plate was about 15 kg/dm 2 . The total specific surface area per unit cell, therefore, was about 630 m 2 /cell for the positive active material, about 57 m 2 /cell for the negative active material, and about 10 m 2 /cell for the separators. Cell elements produced as described above were added severally in 100, 92.5, 90, 87.5, 85, 80, and 70 cc/cell of the electrolyte and then stood for 24 hours. After standing, they were lifted from the containers and examined to determine the amounts of electrolyte contained in the positive plates, negative plates, and separators. With the addition of 100 cc/cell, a certain amount of free electrolyte apparently existed in the cell. With the addition of 100 cc/cell of electrolyte, the volume of electrolyte contained per unit weight was 0.14 cc/g for the positive active material, 0.17 cc/g for the negative active material, and 7.8 cc/g for the separators. Based on these values, each taken as 100%, the changes in the volumes of the electrolyte contained in the positive plates, negative plates, and separators were evaluated. The results were as shown in FIG. 1. Though with the addition of 100 cc/cell there existed some free electrolyte, in FIG. 1, this value indicated as the point at which "the ratio of the volume of the added electrolyte to the total pore volume of the cell element" was 100%. From FIG. 1, it is noted that when the cell elements are formed of components possessing pore diameter, specific surface area, and other properties as the electrolyte was added in varying amounts to the cell element, there was a reduction in the amount of electrolyte in the separators and there was no change in either the positive active material or the negative active material. The fact indicates that when a battery is produced by assembling such components with these particular properties, the pores of the positive active material and the negative active material are always filled with the electrolyte and the separators permit presence of voids not filled with the electrolyte even when the total amount of the electrolyte is decreased by overcharging. Even if the amount of the electrolyte is decreased by overcharging, the positive plates and the negative plates are still fully filled with the electrolyte. Since the high-rate discharge characteristic is affected by the electrolyte contained in the positive plates and the negative plates, the cell element with such a characteristic is enabled to maintain the high-rate discharge characteristic at a sufficiently high level even when the electrolyte is decreased by overcharging. Besides, the separators possess the voids which are necessary for the oxygen gas evolved at the positive plates during overcharging to the transported from the positive plates to the negative plates. It is, accordingly, expected that the efficiency of the absorption of the oxygen gas reaches an exceedingly high level when the amount of the electrolyte is decreased to a certain level. Sealed lead-acid batteries were obtained by inserting the cell elements assembled as described above in a container, welding a strap, joining a lid to the container, adding dilute sulfuric acid with 1.30 specific gravity at an amount of 100 cc/cell, and fitting in a safety valve with a venting pressure of 0.2 kg/cm 2 . The sealed lead-acid batteries thus obtained exhibited a 10-hour rate discharge capacity of 11 AH, a 10C (110 A) discharged duration of 3 minute 00 second, and a 5-second voltage at discharge of 1.80 V per unit cell. These batteries were overcharged at a current of 3C (33 A) to decrease forcedly 5, 10, 15, 20, and 25 cc in the volume of electrolyte per cell, respectively. These batteries for the test were subjected to 110 A discharged at 25° C. The results were as shown in FIG. 2. It is noted from FIG. 2 that the sealed lead-acid batteries of the present invention retained the superior high-rate discharge characteristic even after the volumes of their electrolyte were decreased. FIG. 2 shows that the value of the 5-second voltage at discharge gradually decreases in accordance with the decrease of the electrolyte grows. This behavior can be explained on the basis that since the amount of the electrolyte decreased in the separators (FIG. 1), the resistance in the separators increased proportionately. Sealed lead-acid batteries which had the same construction as described above but contained 95 cc/cell of electrolyte were subjected to an alternating charging and discharging cycle-test of 4 A discharge for 2 hours and 1.7 A recharge for 6 hours. At intervals of 50 cycles, the batteries were given a high-rate discharge test at a discharge current of 110 A and a 3-hour rate discharge test. The change in the high-rate discharge characteristic along the advance of cycles is shown in FIG. 3. In the test, the efficiency of gas recombination averaged 80% during the first 50 ∞ and it was substantially 100% in the subsequent cycles, indicating no decrease in the amount of the electrolyte. This means that the sealed lead-acid battery of this invention exhibits little or no sparing decline of the high-rate discharge characteristic after repeated operation of charging and discharging cycles and possesses a long service life. The conventional sealed lead-acid battery according to the invention disclosed in U.S. Pat No. 3,862,861, for example, was assembled with the positive plates and negative plates both of an extremely thin thickness of more or less 1.0 mm and a very large plate surface area, which were enable to lower or reduce the discharge current density and to improve the high-rate discharge characteristics. During the 10C discharge of the conventional sealed lead-acid battery, the discharge current density based on one side-surface area of the positive plate is about 0.3 A/cm 2 and the discharge duration is about one minute 50 seconds to about two minutes 30 seconds. When the sealed lead-acid battery of this invention is tested under the same conditions, the discharge duration is about three minutes in spite of the condition that the discharge current density based on one side surface area of the positive plate is about 0.6 A/cm 2 , which is twice larger that of the conventional sealed lead-acid battery. To obtain a superior high-rate discharge characteristic without sacrificing the other characteristics, the optimum thickness of the grids for the positive plates is from 3 to 4 mm. By fixing the proper thickness of the grids within that range, the proper thickness of the separators is able to be used calculated eventually. Moreover, this invention permits the sealed lead-acid battery to maintain the high-rate discharge characteristics during its long service life. Further, even at a lower stacking pressure the sealed lead-acid battery of this invention can be expected to have a longer service life than the sealed lead-acid battery conforming to the invention of U.S. Pat. No. 3,862,861 because the grids of this invention are about three times thicker than that of the battery of the noted U.S. patent. A sealed lead-acid battery of this invention can be obtained by selecting appropriately the positive plates, negative plates and the separators with a certain suitable range of pore diameter, specific surface area and other properties so as to become to the construction within the size of plate which comprises a larger amount of electrolyte contained in the positive and negative active materials than that in the separators and so as to be no decrease in the amount of electrolyte in the positive and negative active materials in spite of the condition that the total volume of electrolyte in the cell is reduced due to overcharging. That is in the case of the preferred embodiment described above, by evaluating the distribution of the electrolyte content of the cell element within the plate size, the positive plates contain about 25 cc/cell, negative plates contain about 23 cc/cell, and the separators contain about 34 cc/cell, representing the content ratios of about 30.5% for the positive plates, about 28.0% for the negative plates, and about 41.5% for the separators and indicating that the sum of the electrolyte contained in the positive plates and the negative plates is about 60% of the whole electrolyte so contained. Moreover, the electrolyte contained in the positive and negative plates remains intact and that contained in the separators alone is lost when the whole amount of the electrolyte is decreased due to the water electrolysis during overcharging, therefor the ratio sum of the electrolyte contained in the positive plates and the negative plates to the whole amount of the electrolyte in the cell gradually increased from the aforementioned value of 60%. Thus, the high-rate discharge characteristic cannot be impaired. As mentioned above, in order to establish the condition that only the electrolyte in the separators decreases and the electrolyte in the positive plates and the negative plates always remains filling them when the total amount of the electrolyte is decreased, the separators for use in the battery must be selected so that the electrolyte absorption and retention power of capability of separators will be lower than that of the positive active material and the negative active material. Although it is not clarified completely what properties determine the electrolyte absorption and retention power or capability of each of the component elements of the cell element, it may be safely inferred that the electrolyte absorption power and the elecrtrolyte retention capability are affected by the wettability of the each component with the electrolyte, the specific surface area of each component per unit volume, the pore diameter distribution, and so on. When the foregoing preferred embodiment is reviewed in terms of specific surface area (Sv) per unit volume on the basis that the positive plates, negative plates, and separators have 8, 11, and 2.5 g/cc as their respective values of true specific gravity, the values of Sv is found to be about 28, about 4.73, and about 3.6 m 2 /cc., respectively. Thus, the separators are shown to have the smallest value of Sv. The separators marketed under trademark designation Dexter #225B (product of The Dexter Corp., USA) are of the separators usable for batteries of this kind. The separators of Dexter #225B have a specific surface area of about 2.5 m 2 /g, which is greater than that of the separators involved in the preferred embodiment by this invention, 1.45 m 2 /g and which is corresponding to be Sv of 6.25 m 2 /cc on the basis of its true specific gravity of 2.5 g/cc, which is a value larger than that of the negative active material. If the separators of Dexter #225B are used in the sealed lead-acid battery by this invention, there is a possibility that the pores in the positive plates and the negative plates will not be substantially filled with the electrolyte when the total amount of the electrolyte is decreased. Further, because separators of Dexter #225B have an average pore diameter of about 3 μm, which is a value smaller than the value about 7 μm shown by the separators of the preferred embodiment, and eventually the electrolyte absorption and retention power of separators is stronger, there remains the above-mentioned anxiety. When separators having such a high Sv value as Dexter 225B are effectively used in the sealed lead-acid battery by the present invention, the plates, particularly the negative plates are required to have a larger specific surface area. The plates, therefore, are required to be made of lead oxide powder with much smaller particle diameter than above or most be made of a material incorporating therein various additives which are capable of notably increasing the specific surface area of the plates. The characteristics disclosed by this invention that the electrolyte should substantially fill the pores of the plates and that there exist unfilled voids in part of the pores of the separators is fulfilled by using separators which have a smaller, preferably slightly smaller electrolyte absorption and retention power or capability than the plates. Such types of separators are also usable in sealed lead-acid batteries which require no or inferior high-rate discharge characteristics, namely such as the sealed lead-acid batteries for emergency power sources in which the distance between each plates is from about 1 to 2.5 mm. This kind of sealed lead-acid battery is also embraced by the present invention. What is important is that the separators to be adopted should possess a smaller electrolyte absorption and retention power or capability than the plates. Although the inventors have not yet found the characteristic properties completely which permits suitable expression of the electrolyte absorption and retention power and capability, when the cell element is assembled as specifically discussed in the preferred embodiment, the electrolyte is distributed so that the pores in the active materials of the plates remain fully filled with the electrolyte and the pores in the separators permit partial existence of voids when the total volume of the electrolyte is decreased. By using the cell element with the construction as described above, there can be obtained a sealed lead-acid battery which enables to maintain not only the superior low rate discharge characteristic but also the initial-stage high-rate discharge characteristic for a long time during the service life of the battery even when the total amount of the electrolyte is decreased. The initial-stage high-rate discharge characteristic itself is controlled preponderantly by the distances between the positive plates and the negative plates, and the amount of electrolyte in positive active material and the negative active material, particularly the amount of sulfuric acid contained in the positive active material. For example, when the battery is so produced that the distances between each plate have a thickness of 2.0 mm and the sum of the amount of the electrolyte contained in the positive active material and the negative active material is 40% of the total electrolyte (then the content in the separators is 60%), high-rate discharge characteristic is not very satisfactory. If the separators of the battery have a higher capacity for absorption and retention of the electrolyte than the plates, the high-rate discharge characteristic of the battery may be further degraded because the amount of the electrolyte in the plates gradually decreases as the total electrolyte of the battery decreases owing to the water electrolysis. When the separators assembled in the cell element have a smaller electrolyte absorption and retention power or capability than the plates as disclosed by this invention, the produced battery is characterized by the matter that the initial-stage high-rate discharge characteristic can be retained intact in spite of the decrease of the total amount of the electrolyte due to water electrolysis. It can be easily explained that since the time required for diffusion of the oxygen gas through the separator increases in proportion as the distances between the positive plate and negative plate are widened in thickness, the efficiency of gas recombination tends to degrade in proportion at the distances between the plates are widened. In the sealed lead-acid battery by this invention, bacause the voids become to be formed in the separators in consequence of the decrease of the electrolyte due to water electrolysis such a situation permits easy transport of the oxygen gas from the positive plates to the negative plates, and thus, the efficiency of gas recombination is amply high even when the distances between the plates are widened. The sealed lead-acid battery of this invention, when intended for an application necessitating the superior high-rate discharge characteristic, is disclosed by using separators with a thinner thickness than the plates, particularly the positive plates. To prevent short-circuiting and to ensure satisfactory high-rate discharge characteristic, the thickness of the separators is desired to be in the range of 0.4 to 0.25 times the thickness of the positive plates. The distance between the positive plates and the negative plates is 0.7 to 1.0 mm when the thickness of the positive plates is 3 to 4 mm. In the preferred embodiment described above, for example, the separators used therein had a thickness of about one third of the thickness of positive plates. The reason for such a range is that the high-rate discharge characteristic is degraded if the thickness exceeds 0.4 times and the possibility of short-circuiting arises if the thickness is less than 0.25 times. With respect to theoretical capacity, in the sealed lead-acid battery of this type, the total amount of the positive active material and the negative active material is greater than that of the electrolyte. That is, the capacity of the sealed lead-acid battery is affected by the amount of the electrolyte (namely the amount of sulfuric acid) and, even toward the end of discharge, the active materials still retain some undischarged portion. Such a condition applies to the sealed lead-acid battery of this invention. In the overdischarged condition, the electrolyte becomes nearly water. Particularly in the battery of the present invention, this phenomenon is outstandingly conspicuous because the sum of the amount of the electrolyte contained in the positive plates and the negative plates is about 60% or more for the total electrolyte. When the battery is left standing long at the overdischarged state, lead is dissolved. Because the dissolved lead ions is precipitated to be metal in the separators during the next recovery charging, there is a high possibility of causing short-circuit between the positive plates and the negative plates. When the battery is designed specifically to be used for high-rate discharge, the possibility of short-circuit is more outstanding because the thickness of separators is thinner than that of plates. To reduce the concentration of the dissolved lead, therefore, it is desirable to add to the electrolyte such an alkali metal salt as Na, K, or Li salt as an impurity matter. Although such an addition of an impurity matter constitutes itself a known technique to the art, in the case of the sealed lead-acid battery of this invention, the amount of impurity matters must be greater than the normally accepted levels or ranges because the sum of the amount of the electrolyte contained in the positive active material and the negative active material is greater than the amount of the electrolyte contained in the separators and because the thickness of the separators is thinner than that of the plates. To determine the optimum amount of the addition of the alkali metal salts, the following experiments were carried out. Experiments: Batteries were produced with the same construction as used in the aforementioned tests for service life through alternating charging and discharging cycle. Electrolytes were prepared by adding 0.1, 0.5, 1.0, 1.5, 2.0, 5.0 and 10.0%, respectively, of K 2 SO 4 to dilute sulfuric acid solution with 1.30 specific gravity. The electrolytes were severally added to each battery same in a volume of 90 cc per cell. These batteries were discharged to 0 V and then left standing at the outer short-circuit state at room temperature for two weeks. Then these batteries were checked whether there occurred the short-circuiting and determined whether or not they could be recharged. The results were as shown in Table 1 below. It is noted from Table 1 that the amount of K 2 SO 4 added is desired to be more than at least 1.0%. Although this experiment offered insufficient definite data for the upper limit to the amount of the alkali metal salt, it is practically desirable to fix the upper limit at 5.0% in taking into consideration of self discharge and operation of dissolving. TABLE 1______________________________________Amount of K.sub.2 SO.sub.4 added (%) Occurrence of short-circuit______________________________________0.1 Yes0.5 Yes1.0 No1.5 No2.0 No5.0 No10.0 No______________________________________ In the case of the sealed lead-acid battery by the present invention, in order to improve the high-rate discharge characteristics particularly at low temperatures, the amount of the positive active material is desired to be larger than that of the negative active material. It is well known that in the conventional lead-acid battery with the free electrolyte the high-rate discharge characteristic at low temperature is controlled mainly by the negative plates. In the case of the sealed lead-acid battery by this invention, the high-rate discharge characteristic at low temperature is controlled not by the negative plates but by the amount of sulfuric acid present in the positive active material. It is, therefore, desirable for the pore volume contained in the positive active material to be equal to or greater than that in the negative active material. When the specific pore volume (Vsp) of the positive active material is evaluated to be 0.14 cc/g and that (V SN ) of the negative active material at 0.17 cc/g, for example, since the ratio of V SN /V sp is 1.21, the amount of the active material for the positive plates is desired to be 1.21 times or more than the amount for the negative plates, although the amount of the pores in positive plate is variable with the amount of sulfuric acid used in mixing the finely divided lead oxide powder. In terms of theoretical capacity of active materials, therefore, the positive plates are desired to be larger in the capacity than the negative plates in the sealed lead-acid battery by the present invention. In evaluating the ratio of the positive active material and the negative active material to the theoretical capacity 1÷3.867=0.259 for the negative plates and 1.21÷4.463=0.271 for the positive plates and, therefore, the ratio of the theoretical capacity of the negative plates to that of the positive plates is desired to be less than 0.954 because 0.259÷0.271=0.954. It is clear from the data given in the preferred embodiment that such a this relationship has no adverse effect upon the "oxygen cycle." As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

The invention involves a sealed lead-acid battery comprising a cell element having positive plates, negative plates and separators, and electrolyte retained within micropore of the cell element. The micropores of both the plates is substantially filled with the electrolyte, while the micropores of the separators are not completely filled with the electrolyte. The voids formed partially in the micropores of the separators permit transport of the oxygen gas from the positive plates to the negative plates. Such a sealed lead-acid battery has long service life, and excels in ability to O 2 absorb gases and reproduce water during overcharging and to recover by charging after a long overdischarged-state storage.

BACKGROUND OF THE INVENTION This invention is generally in the area of drug delivery systems, especially in the area of oral, rectal, vaginal and nasal drug delivery. Drug delivery takes a variety of forms, depending on the agent to be delivered and the administration route. A preferred mode of administration is non-invasive; i.e., administration via nasal or oral passages. Some compounds are not suited for such administration, however, since they are degraded by conditions in the gastrointestinal tract or do not penetrate well into the blood stream. Controlled release systems for drug delivery are often designed to administer drugs in specific areas of the body. In the gastrointestinal tract it is critical that the drug not be entrained beyond the desired site of action and eliminated before it has had a chance to exert a topical effect or to pass into the bloodstream. If a drug delivery system can be made to adhere to the lining of the appropriate viscus, its contents will be delivered to the targeted tissue as a function of proximity and duration of the contact. There are two major aspects to the development of an adhesive bond between a polymer and the gastrointestinal tissue: (i) the surface characteristics of the bioadhesive material, and (ii) the nature of the biological material with which the polymer comes in contact. The intestinal mucosa is formed of a continuous sheet of epithelial cells of absorptive and mucin-recruiting cells. Overlying the mucosa is a discontinuous protective coating, the mucus, which is made of more than 95% water, as well as electrolytes, proteins, lipids and glycoproteins—the latter being responsible for the gel-like characteristics of the mucus. These glycoproteins consist of a protein core with covalently attached carbohydrate chains terminating in either sialic acid or L-fucose groups. The carbohydrate structure of the intestinal mucous glycoproteins is similar to that of the glycoproteins which are part of the epithelial cell membrane. The mucous glycoproteins act as “dummy receptors” for carbohydrate binding ligands which have evolved in nature to allow microorganisms and parasites to establish themselves on the gut wall. One function of the mucus is to intercept these ligands and associated infective agents and thereby protect the mucosa. An orally ingested product can adhere to either the epithelial surface or the mucus. For the delivery of bioactive substances, it would be advantageous to have a polymeric device adhere to the epithelium rather than the mucous layer. For some types of imaging purposes, adhesion to both the epithelium and mucus is desirable whereas in pathological states, such as in the case of gastric ulcers or ulcerative colitis, adhesion to cells below the mucosa may be unavoidable. Bioadhesion in the gastrointestinal tract proceeds in two stages: (1) viscoelastic deformation at the point of contact of the synthetic material into the mucus substrate, and (2) formation of bonds between the adhesive synthetic material and the mucus or the epithelial cells. Several microsphere formulations have been proposed as a means for oral drug delivery. These formulations generally serve to protect the encapsulated compound and to deliver the compound into the blood stream. Enteric coated formulations have been widely used for many years to protect drugs administered orally, as well as to delay release. Other formulations designed to deliver compounds into the blood stream, as well as to protect the encapsulated drug, are formed of a hydrophobic protein, such as zein, as described in PCT/US90/06430 and PCT/US90/06433; “proteinoids”, as described in U.S. Pat. No. 4,976,968 to Steiner; or synthetic polymers, as described in European Patent application 0 333 523 by The UAB Research Foundation and Southern Research Institute. EPA 0 333 523 describes microparticles of less than ten microns in diameter that contain antigens, for use in oral administration of vaccines. The microparticles are formed of polymers such as poly(lactide-co-glycolide), poly(glycolide), polyorthoesters, poly(esteramides), polyhydroxybutyric acid and polyanhydrides, and are absorbed through the Peyer's Patches in the intestine. It would be advantageous if there was a method or means for increasing the absorption of these particles through the mucosal lining, or for delaying still further transit of the particles through the nasal or gastrointestinal passages. Duchene, et al., Drug Dev. Ind. Pharm. 14(2&3), 283-318 (1988), reviews the pharmaceutical and medical aspects of bioadhesive systems for drug delivery. “Bioadhesion” is defined as the ability of a material to adhere to a biological tissue for an extended period of time. Bioadhesion is clearly one solution to the problem of inadequate residence time resulting from the stomach emptying and intestinal peristalsis, and from displacement by ciliary movement. For bioadhesion to occur, an intimate contact must exist between the bioadhesive and the receptor tissue, the bioadhesive must penetrate into the crevice of the tissue surface and/or mucus, and chemical bonds must form. Bioadhesive power of the polymers is affected by both the nature of the polymer and by the nature of the surrounding media. Duchene, et al., tested polymers for bioadhesion by measuring the surface tension between a plate containing a mucous sample and a polymer coated glass plate. They review other systems using intestinal membrane rather than a mucosal solution, and in vivo studies using rats and radiolabeled polymeric material in a gelatin capsule. A number of polymers were characterized as to their bioadhesive properties but primarily in terms of “excellent” or “poor”. Polycarbophils and acrylic acid polymers were noted as having the best adhesive properties, although the highest adhesive forces were still less than 10 mN/cm 2 . Others have explored the use of bioadhesive polymers. Smart, et al., J. Pharm. Pharmacol . 36:295-299 (1984), reported on a method to test adhesion to mucosa using a polymer coated glass plate contacting a dish of mucosa. A variety of polymeric materials were tested, including sodium alginate, sodium carboxymethylcellulose, gelatin, pectin, and polyvinylpyrrolidone. Gurney, et al., Biomaterials 5, 336-340 (1984), concluded that adhesion may be effected by physical or mechanical bonds; secondary chemical bonds; and/or primary, ionic or covalent bonds. Park, et al., Alternative Approaches to Oral Controlled Drug Delivery: Bioadhesives and In - Situ Systems 163-183 J. M. Anderson and S. W. Kim, ed., Recent Advances in Drug Delivery (Plenum Press N.Y. 1984), report on the use of fluorescent probes in cells to determine adhesiveness of polymers to mucin/epithelial surfaces. Their results indicated that anionic polymers with high charge density appear to be preferred as adhesive polymers. None of these studies involved the study of tensile measurement between microspheres and intestinal tissue. Microspheres will be affected by other factors, such as the mucosal flow, peristaltic motion, high surface area to volume ratio. Mikos, et al., in J. Colloid Interface Sci . 143, 2:366-373 (May 1991) and Lehr, et al., J. Controlled Rel. Soc . 13:51-62 (1990), both disclose the bioadhesive properties of polymers used for drug delivery: polyanhydrides and polyacrylic acid, respectively. Mikos, et al., report that the bioadhesive forces are a function of surface area, and are significant only for particles in excess of 900 microns in diameter (having an adhesive force of 120 μN, equivalent to 10.9 mN/cm 2 ), when measured in vitro. However, they also note that this may not be an adequate adhesive force in vivo, since the larger particle size is also subjected to greater flow conditions along the mucosa which may serve to displace these larger particles. In addition, Mikos, et al., found very small forces for particles smaller than 750 μ. Lehr, et al., screened two commercially available microparticles of a diameter in excess of 500 microns formed of copolymers of acrylic acid, using an in vitro system, and determined that one copolymer “polycarbophil” increased adhesion over a control but that the other polymer did not. Polymeric coatings were also applied to polyhydroxyethylmethacrylic acid and tested in an in vivo model. As shown in Table 1, the maximum adhesive force was approximately 9 mN/cm 2 for polycarbophil. Most prior art techniques for measuring in vitro bioadhesion are based on tensile experiments. These techniques were mainly designed for large tablets or polymer coated onto glass plates. Only a few in vitro techniques for direct measurement of adhesion forces between individual microcapsules and intestinal tissue are known. Some publications used a flow channel method. However, the only reported results are static measurements where the mucoadhesive force exerted on each particle was determined by placing small particles over intestinal mucosa and measuring the immersed surface area and the directional contact angles using video microscopy, by Mikos, et al. It is therefore an object of the present invention to provide bioadhesive polymeric microspheres that are useful for drug delivery via the mucosal membranes. It is a further object of the present invention to provide polymeric microspheres which can be used for imaging studies. It is another object of the present invention to provide a method for determining bioadhesiveness of polymeric microspheres. SUMMARY OF THE INVENTION Bioadhesive polymers in the form of, or as a coating on, microcapsules containing drugs or bioactive substances which may serve for therapeutic, diagnostic, or diagnostic purposes in diseases of the gastrointestinal tract, are described. The polymeric microspheres all have a bioadhesive force of at least 11 mN/cm 2 (110 N/CM 2 ). Techniques for the fabrication of bioadhesive microspheres, as well as a method for measuring bioadhesive forces between microspheres and selected segments of the gastrointestinal tract in vitro are also described. This quantitative method provides a means to establish a correlation between the chemical nature, the surface morphology and the dimensions of drug-loaded microspheres on one hand and bioadhesive forces on the other, allowing the screening of the most promising materials from a relatively large group of natural and synthetic polymers which, from theoretical consideration, should be used for making bioadhesive microspheres. These methods and materials are particularly useful for the oral administration of a wide range of drugs, particularly sulfonamides (e.g., sulfasalazine) and glycocorticoids (e.g., betamethasone), all of which are being used for treatment of bowel diseases. Bioadhesive microspheres containing barium sulphate for use in imaging have the following advantages over conventional administration of barium: (1) produce more uniform coverage as well as better adhesion of the barium to the mucosa in the stomach and the intestine, (2) eliminate the problem of barium sulphate precipitation by protecting it from the local pH. Encapsulation of radio-opaque materials and drugs in the same type of polymer but in different microcapsules and simultaneous administration of both type of microcapsules could provide a useful tool for studying the exact location of the delivery system in the GI tract. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a tissue chamber used to measure bioadhesive forces of polymeric microspheres. FIG. 2 is a graph of force (mg) versus stage position (mm) for a typical P(CPP:SA) microsphere. FIG. 3 a is a graph of force of detachment per projected surface area (mN/cm 2 ) for various polymers. The polymers used in this study included the following: alginate (one sample prepared several hours prior to testing (alginate (f)) [diam.=700μ] and another prepared several months prior to testing and left in a Ca + solution (alginate (o)) [diam.=2400μ]), alginate/polyethylene imide (alginate/PEI) [diam.=2100μ], carboxymethylcellulose (CMC) [diam.=1800μ], chitosan (high molecular weight) [diam.=2000μ], polyacrylonitrile/polyvinyl chloride (PAN/PVC) [diam.=2900μ], polylactic acid: MW=2,000 (one sample made by the hot melt technique (PLA 2K HM) [diam. =780μ] and one sample made by the solvent evaporation technique (PLA 2K SE) [diam.=800μ]), polystyrene [diam.=800μ], poly[bis(p-carboxy phenoxy) propane-co-sebacic anhydride] made with sudan red dye (P(CPP:SA)) [diam.=780μ], and poly[fumaricco-sebacic anhydride] (one sample made with acid orange dye (P(FA:SA)A) [diam.=780μ] and one sample containing no dye (P(FA:SA) B [diam.=780μ]). The forces were measured as the weight (mg) required to remove the microsphere from the intestinal tissue after a seven minute adhesion time using the Cahn electrobalance and converted to units of force (mN). These forces were then normalized by dividing by the surface area in contact with the tissue for each case. The surface areas were determined by the projection of the spherical cap of the microsphere that penetrated below the surface level of the tissue (Area=πR 2 −π(R−a) 2 , where ‘R’ is the microsphere radius and ‘a’ is the depth of penetration). All force/surface area values are presented with the standard errors of measure (SEM). FIG. 3 b is a graph of the work of detachment (nJ) for the polymeric microspheres described in FIG. 3 a . Work values were determined from the areas beneath the curves of the force versus distance graphs produced with the Cahn electrobalance, and are presented with standard errors of measure. FIG. 3 c is a graph of work of detachment per projected surface area (pJ/cm 2 ) for the polymeric microspheres described in FIG. 3 a . All work/surface area values are presented with the standard errors of measure. FIG. 4 a is a graph of the weight of detachment versus Microsphere Diameter. The microspheres in this study were poly[bis(p-carboxy phenoxy) propane-co-sebacic anhydride] made with sudan red dye made by the hot melt technique. The microsphere diameters were measured with a micrometer prior to testing. The weight of detachment is the weight, measured by the Cahn electrobalance, which is required to remove the microsphere from the intestinal tissue after a seven minute adhesion time. FIG. 4 b is a graph of the force of detachment/surface area (mN/cm 2 ) versus microsphere diameter (microns) for p(CPP:SA) microspheres. FIG. 5 a is a graph of the weight of detachment (mg) versus microsphere diameter (microns) for poly[fumaric-co-sebacic anhydride] (p(FA:SA)) made by the hot melt technique. The microsphere diameters were measured with a micrometer prior to testing. The weight of detachment is the weight, measured by the Cahn electrobalance, which is required to remove the microsphere from the intestinal tissue after a seven minute adhesion time. FIG. 5 b is a graph for force of detachment per projected surface area versus microsphere diameter for P(FA:SA) microspheres. In this figure, the values from FIG. 3 c have been normalized by the projected surface areas as described in FIG. 3 a. FIG. 6 is a X-ray print of rats fed with barium sulphate loaded P(CPP:SA) microspheres. FIG. 7 is a graph of intestinal and stomach transit time (hours) for barium, polystyrene and P(CPP:SA) as a function of bead size (microns). FIG. 8 a is a SEM of microsphere adhering to the mucosa. FIG. 8 b is a photograph of a p(FA:SA) microsphere in the device of FIG. 1 being detached from porcine jejunum using the Cahn electrobalance. DETAILED DESCRIPTION OF THE INVENTION In general terms, adhesion of polymers to tissues may be achieved by (i) physical or mechanical bonds, (ii) primary or covalent chemical bonds, and/or (iii) secondary chemical bonds (i.e., ionic). Physical or mechanical bonds can result from deposition and inclusion of the adhesive material in the crevices of the mucus or the folds of the mucosa. Secondary chemical bonds, contributing to bioadhesive properties, consist of dispersive interactions (i.e., Van der Waals interactions) and stronger specific interactions, which include hydrogen bonds. The hydrophilic functional groups responsible for forming hydrogen bonds are the hydroxyl (—OH) and the carboxylic groups (—COOH). Adhesive microspheres have been selected on the basis of the physical and chemical bonds formed as a function of chemical composition and physical characteristics, such as surface area, as described in detail below. These microspheres are characterized by adhesive forces to mucosa of greater than 11 mN/cm 2 . Classes of Polymers Useful in Forming Bioadhesive Microspheres. Suitable polymers that can be used to form bioadhesive microspheres include soluble and insoluble, nonbiodegradable and biodegradable polymers. These can be hydrogels or thermoplastics, homopolymers, copolymers or blends, natural or synthetic. A key feature, however, is that the polymer must have a bioadhesive force of between 110 N/m 2 (11 mN/cm 2 ) and 5000 N/m 2 to a mucosal membrane of a patient. Two classes of polymers appear to have potentially useful bioadhesive properties: hydrophilic polymers and hydrogels. In the large class of hydrophilic polymers, those containing carboxylic groups (e.g., poly[acrylic acid]) exhibit the best bioadhesive properties. One could infer that polymers with the highest concentrations of carboxylic groups should be the materials of choice for bioadhesion on soft tissues. Other promising polymers were: sodium alginate, carboxymethylcellulose, hydroxymethylcellulose and methylcellulose. Some of these materials are water-soluble, while others are hydrogels. Hydrogels have often been used for bioadhesive drug delivery; however, one big drawback of using hydrogels is the lack of long-term stability during storage which is a problem for therapeutic applications. Rapidly bioerodible polymers such as poly[lactide-co-glycolide], polyanhydrides, polyorthoesters—which would expose carboxylic groups on the external surface as their smooth surface erodes—are excellent candidates for bioadhesive drug delivery systems in the gastrointestinal tract. Biodegradable polymers are more stable than hydrogels. In addition, polymers containing labile bonds, such as polyanhydrides and polyesters, are well known for their hydrolytic reactivity. Their hydrolytic degradation rates can generally be altered by simple changes in the polymer backbone. Representative natural polymers are proteins, such as zein, serum albumin, or collagen, and polysaccharides, such as cellulose, dextrans, and alginic acid. Representative synthetic polymers include polyamides, polycarbonates, polyalkylenes, polyalkylene glycols, polyalkylene oxides, polyalkylene terephthalates, polyvinyl alcohols, polyvinyl ethers, polyvinyl esters, polyvinyl halides, polyvinylpyrrolidone, polyglycolides, polysiloxanes, polyurethanes, alkyl cellulose, hydroxyalkyl celluloses, cellulose ethers, cellulose esters, nitrocelluloses, polymers of acrylic and methacrylic esters, poly[lactide-co-glycolide], polyanhydrides, polyorthoester blends and copolymers thereof. Specific examples of these polymers include cellulose acetate, cellulose propionate, cellulose acetate butyrate, cellulose acetate phthalate, carboxymethyl cellulose, cellulose triacetate, cellulose sulphate, poly(methyl methacrylate), poly(ethyl methacylate), poly(butyl methacrylate), poly(isobutyl methacrylate), poly(hexyl methacrylate), poly(isodecyl methacrylate), poly(lauryl methacrylate), poly(phenyl methacrylate), poly(methyl acrylate), poly(isopropyl acrylate), poly(isobutyl acrylate), poly(octadecyl acrylate), polyethylene, polypropylene, poly(ethylene glycol), poly(ethylene oxide), poly(ethylene terephthalate), poly(vinyl alcohols), poly(vinyl acetate), poly(vinyl chloride), polystyrene and polyvinylpyrrolidone, polyurethane, polylactides, poly(butyric acid), poly(valeric acid), poly[lactide-co-glycolide], polyanhydrides, polyorthoesters, poly(fumaric acid), and poly(maleic acid). These polymers can be obtained from sources such as Sigma Chemical Co., St. Louis, Mo., Polysciences, Warrenton, Pa., Aldrich, Milwaukee, Wis., Fluka, Ronkonkoma, N.Y., and BioRad, Richmond, Calif. In the studies detailed below, a variety of polymer microspheres were compared for adhesive force to mucosa. Negatively charged hydrogels, such as alginate and carboxymethylcellulose, that expose carboxylic groups on the surface, were selected, as well as some positively-charged hydrogels, such as chitosan. The rationale behind this choice is the fact that most cell membranes are actually negatively charged and there is still no definite conclusion as to what the most important property is in obtaining good bioadhesion to the wall of the gastrointestinal tract. Thermoplastic polymers: (a) non-erodible, neutral polystyrene, and (b) semicrystalline bioerodible polymers that generate carboxylic groups as they degrade—polylactides and polyanhydrides, were also selected. Polyanhydrides are good candidates for bioadhesive delivery systems since, as hydrolysis proceeds, more and more carboxylic groups are exposed to the external surface. Polylactides erode by bulk erosion; furthermore, the erosion is slower. In designing these systems as bioadhesive polymers, polymers that have high concentrations of carboxylic acid were preferred. This was done by using low molecular weight polymers (Mw 2000), since low molecular weight polymer contain high concentration of carboxylic acids at the end groups. Measurement of Bioadhesive Studies Using a Tensile Technique The adhesive forces between polymer microspheres and segments of intestinal rat tissue can be measured using the Cahn DCA-322, as shown in FIG. 1 . Although this piece of equipment is designed for measuring contact angles and surface tensions using the Wilhelmy plate technique, it is also an extremely accurate microbalance. The DCA-322 system includes a microbalance stand assembly, a Cahn DACS computer, and an Okidata Microline 320 dot matrix printer. The microbalance unit consists of stationary sample and tare loops and a moving stage powered by a stepper motor. The balance can be operated with samples weighing up to 3.0 g, and has a sensitivity rated at 0.001 dynes. The stage speed can be adjusted from 20 to 264 μm/sec using the factory installed motor, or from 2-24 μm/sec using the optional slow motor. Adhesive forces were measured by attaching a polymer sample to one of the sample loops and placing an adhesive substrate 10, intestinal tissue, below it on the moving stage 20. For adhesive measurements, 1.5 cm sections are cut from the excised intestine. These were then sliced lengthwise and spread flat, exposing the lumen side. The samples were then placed in a temperature-regulated chamber 30 , clamped 32 at their edges, and covered with approximately 0.9 cm high level of phosphate buffer saline, as shown in FIG. 1 . Physiologic conditions were maintained in the chamber. The chamber was then placed in the microbalance enclosure and a microsphere, mounted on a wire and hung from the sample loop of the microbalance, was brought in contact with the tissue. The microspheres were left in contact with the tissue for seven minutes with an applied force of approximately 0.25 mN and then pulled vertically away from the tissue sample while recording the required force for detachment. The contact area was estimated to be the surface area of the spherical cap defined by the depth of penetration of the bead below the surface level of the tissue. The force values were normalized by the projected area of this cap (Area=πR 2 −π(R−a) 2 , where R is the microsphere radius and a is the depth of penetration. For microspheres larger than 800 μm, a=400 m was used, for smaller microspheres a=R was used. Graphs of force versus distance as well as force versus time were studied. FIG. 2 shows a typical graph of force versus stage position for the P(CPP-SA) 20:80 microspheres. Point A in FIG. 2 indicates the applied force, which can be varied in each experiment, and which indirectly affects the degree of penetration into the tissue. Portion AB indicates the adhesion time, the time the sphere is left to interact with the tissue before movement of the stage is started to separate the surfaces. Segment BC indicates the elevation of the sphere to 0 mg applied force (point C). During the early part of the tensile experiment (CD), the force increases as a function of stage position, while the contact area between the sphere and the mucus is assumed to be constant and equal to the surface of the immersed sphere. The next portion of this curve (DE) indicates a period where partial detachment of the polymeric device from the mucus occurred with some changes in the contact area. The last point (E) is the detachment of the sphere from the mucus. In some cases, a detachment does not occur until the microsphere has been moved to a height of 4 mm above the initial level of contact. From these graphs it is possible to determine the maximum force applied to the sample, the maximum adhesive force, the distance required for detachment of the samples and the work of adhesion (the surface under the force versus stage position curves CDE). More importantly, it allows quantification of the adhesive forces of a variety of individual microspheres and correlation of these forces with physical and chemical properties of the polymers. Modification of Bioadhesive Polymers to Increase Bioadhesive Force. The polymers are selected from commercially available polymers based on their adhesive properties using the method described above to determine those polymers forming microspheres (either as solid polymer or as a polymeric coating on a different material) having an adhesive force greater than 11 nN/mg 2 . The microspheres are then formed having an appropriate surface area to provide the desired adhesive forces. The polymers (or polymeric surface) can also be modified as described below to increase the bioadhesive properties of the polymer. For example, the polymers can be modified by increasing the number of carboxylic groups accessible during biodegradation, or on the polymer surface. The polymers can also be modified by binding amino groups to the polymer. The attachment of polyethyleneimine or polylysine-coated acrylamide beads to intestine is probably due to the electrostatic attraction of the cationic groups coating the beads to the net negative charge of the mucus. The mucopolysaccharides and mucoproteins of the mucin layer, especially the sialic acid residues, are responsible for the negative charge coating. Any ligand with a high binding affinity for mucin could also be covalently linked to most microspheres with the appropriate chemistry, such as CDI, and be expected to influence the binding of microspheres to the gut. The ligand affinity need not be based only on electrostatic charge, but other useful physical parameters such as solubility in mucin or else specific affinity to carbohydrate groups. The covalent attachment of any of the natural components of mucin in either pure or partially purified form to the microspheres would decrease the surface tension of the bead-gut interface and increase the solubility of the bead in the mucin layer. The list of useful ligands would include but not be limited to the following: sialic acid, neuraminic acid, n-acetyl-neuraminic acid, n-glycolylneuraminic acid, 4-acetyl-n-acetylneuraminic acid, diacetyl-n-acetylneuraminic acid, glucuronic acid, iduronic acid, galactose, glucose, mannose, fucose, or else any of the partially purified fractions prepared by chemical treatment of naturally occurring mucin, e.g., mucoproteins, mucopolysaccharides and mucopolysaccharide-protein complexes. The covalent attachment of lectins to microspheres would also increase the affinity of the spheres to components of the mucin and mucosal cell layer. Useful lectin ligands include lectins isolated from: Abrus precatroius, Agaricus bisporus, Anguilla anguilla, Arachis hypogaea, Pandeiraea simplicifolia, Bauhinia purpurea, Caragan arobrescens, Cicer arietinum, Codium fragile, Datura stramonium, Dolichos biflorus, Erythrina corallodendron, Erythrina cristagalli, Euonymus europaeus, Glycine max, Helix aspersa, Helix pomatia, Lathyrus odoratus, Lens culinaris, Limulus polyphemus, Lysopersicon esculentum, Maclura pomifera, Momordica charantia, Mycoplasma gallisepticum, Naja mocambique , as well as the lectins Concanavalin A and Succinyl-Concanavalin A. Formation of Microspheres. As used herein, microspheres includes microparticles and microcapsules (having a core of a different material than the outer wall), having a diameter in the nanometer range up to 1 mm. The microsphere may consist entirely of bioadhesive polymer or have only an outer coating of bioadhesive polymer. Microspheres have been fabricated from the different polymers. Polylactic blank microspheres were fabricated by using two methods: solvent evaporation, as described by E. Mathiowitz, et al., J. Scanning Microscopy , 4, 329 (1990); L. R. Beck, et al., Fertil. Steril ., 31, 545 (1979); and S. Benita, et al., J. Pharm. Sci ., 73, 1721 (1984); and hot-melt microencapsulation, as described by E. Mathiowitz, et al., Reactive Polymers , 6, 275 (1987). Polyanhydrides made of bis-carboxyphenoxypropane and sebacic acid with molar ratio of 20:80 (P(CPP-SA) 20:80) (Mw 20,000) were prepared by hot-melt microencapsulation. Poly(fumaric-co-sebacic) (20:80) (Mw 15,000) blank microspheres were prepared by hot-melt microencapsulation. Polystyrene microspheres were prepared by solvent evaporation. Hydrogel microspheres were prepared by dripping the solution from a reservoir though a 250 microliter pipet tip into a stirred ionic bath. The specific conditions for alginate, chitosan, alginate/polyethylenimide (PEI) and carboxymethyl cellulose (CMC) are listed in Table 1. a. Solvent Evaporation. In this method the polymer is dissolved in a volatile organic solvent, methylene chloride. The drug (either soluble or dispersed as fine particles) is added to the solution, and the mixture is suspended in an aqueous solution that contains a surface active agent such as poly(vinyl alcohol). The resulting emulsion is stirred until most of the organic solvent evaporates, leaving solid microspheres. Several different polymer concentrations will be used (0.05-0.20 g/ml). The solution will be loaded with a drug and suspended in 200 ml of vigorously stirred distilled water containing 1% (w/v) poly(vinyl alcohol) (Sigma). After 4 hours of stirring, the organic solvent will have evaporated from the polymer, and the resulting microspheres are washed with water and dried overnight in a lyophilizer. Microspheres with different sizes (1-1000 microns) and morphologies can be obtained by this method. This method is useful for relatively stable polymers like polyesters and polystyrene. However, labile polymers, such as polyanhydrides, may degrade during the fabrication process due to the presence of water. For these polymers, the following two methods, which are performed in completely organic solvents, are more useful. b. Hot Melt Microencapsulation. In this method, the polymer is first melted and then mixed with the solid particles of the dye or drug that have been sieved to less than 50 microns. The mixture is suspended in a non-miscible solvent (like silicon oil), and, while stirring continuously, heated to 5° C. above the melting point of the polymer. Once the emulsion is stabilized, it is cooled until the polymer particles solidify. The resulting microspheres are washed by decantation with petroleum ether to give a free-flowing powder. Microspheres with sizes between one to 1000 microns can be obtained with this method. The external surfaces of spheres prepared with this technique are usually smooth and dense. This procedure is used to prepare microspheres made of polyesters and polyanhydrides. However, this method is limited to polymers with molecular weights between 1000-50000. c. Solvent Removal. This technique was primarily designed for polyanhydrides. In this method, the drug is dispersed or dissolved in a solution of the selected polymer in a volatile organic solvent like methylene chloride. This mixture is suspended by stirring in an organic oil (such as silicon oil) to form an emulsion. Unlike solvent evaporation, this method can be used to make microspheres from polymers with high melting points and different molecular weights. Microspheres that range between 1-300 microns can be obtained by this procedure. The external morphology of spheres produced with this technique is highly dependent on the type of polymer used. d. Hydrogel Microspheres. Microspheres made of gel-type polymers, such as alginate, are produced by dissolving the polymer in an aqueous solution, suspending the barium sulphate or any other active material in the mixture and extruding through a microdroplet forming device, producing microdroplets which fall into a hardening bath, that is slowly stirred. The advantage of these systems is the ability to further modify the surface of the microspheres by coating them with polycationic polymers, like polylysine after fabrication. Microsphere particles are controlled by using various size extruders. Table 1 summarizes the various hydrogels and the concentrations that were used to manufacture them. TABLE 1 Type and Concentration for Hydrogels Fabrication Hydrogel Hydrogel Conc. Bath Type/Conc. Stirring Chitosan 1.0% Tripolyphosphate, 3% 170 rpm Alginate 2.0% Calcium Chloride, 1.3% 160 rpm Alginate/PEI 2.0/6.0% Calcium Chloride, 1.3% 160 rpm CMC 2.0% Lead Nitrate, 10% 100 rpm Chitosan microspheres can be prepared by dissolving the polymer in acidic solution and crosslinking it with tripolyphosphate. Carboxymethyl cellulose (CMC) microspheres were prepared by dissolving the polymer in acid solution and precipitating the microsphere with lead ions. Alginate/polyethylene imide (PEI) were prepared in order to reduce the amount of carboxylic groups on the alginate microcapsule. Materials that can be Incorporated into the Microspheres. There is no specific limitation on the material that can be encapsulated within the bioadhesive polymer. Any kind of bioactive agent, including organic compounds, inorganic compounds, proteins, polysaccharides, or other materials can be incorporated using standard techniques. Examples of useful proteins include hormones such as insulin, growth hormones including somatometins, transforming growth factors, and other growth factors, antigens for oral vaccines, enzymes such as lactase or lipases, and digestive aids such as pancreatin. Examples of useful drugs include ulcer treatments such as Carafate from Marion Pharmaceuticals, antihypertensives or saluretics such as Metolazone from Searle Pharmaceuticals, carbonic anhydrase inhibitors such as Acetazolamide from Lederle Pharmaceuticals, insulin like drugs such as glyburide, a blood glucose lowering drug of the sulfonylurea class, hormones such as Android F from Brown Pharmaceuticals and Testred (methyltestosterone) from ICN Pharmaceuticals, antiparasitics such as mebeandazole (Vermox™, Jannsen Pharmaceutical. Other drugs for application to the vaginal lining or other mucosal membrane lined orifices such as the rectum include spermacides, yeast or trichomonas treatments and anti-hemorrhoidal treatments. In a preferred method for imaging, a radiopaque material such as barium is coated with polymer. Radioactive materials or magnetic materials could be used in place or, or in addition to, the radiopaque materials. Administration of Bioadhesive Microspheres to Patients. The microspheres are administered in suspension or in ointment to the mucosal membranes, via the nose, mouth, rectum, or vagina. Pharmaceutically acceptable carriers for oral or topical administration are known and determined based on compatibility with the polymeric material. Other carriers include bulking agents such as Metamucil™. These microspheres are especially useful for treatment of inflammatory bowel diseases such as ulcerative colitis and Crohn's disease. In ulcerative colitis, inflammation is restricted to the colon, whereas in Crohn's disease, inflammatory lesions may be found throughout the gastrointestinal tract, from the mouth to the rectum. Sulfasalazine is one of the drugs that is used for treatment of the above diseases. Sulfasalazine is cleaved by bacterial within the colon to sulfapyridine, an antibiotic, and to 5-amino salicylic acid, an anti-inflammatory agent. The 5-amino salicylic acid is the active drug and it is needed locally. Direct administration of the degradation product (5-amino salicylic acid) may be more beneficial. A bioadhesive drug delivery system could improve the therapy by retaining the drug for a prolonged time in the intestinal tract. For Crohn's disease, retention of 5-aminosalicylic acid in the upper intestine is of great importance, since bacteria cleave the sulfasalazin in colon, the only way to treat inflammations in the upper area is by local administration of 5-aminosalicylic acid. Gastrointestinal Imaging Barium sulphate suspension is the universal contrast medium used for examination of the upper gastrointestinal tract, as described by D. Sutton, Editor, A Textbook of Radiology and Imaging, Volume 2, Churchill Livingstone, London (1980), even though it has undesirable properties, such as unpalatability and a tendency to precipitate out of solution. Several properties are critical: (a) Particle size: the rate of sedimentation is proportional to particle size (i.e., the finer the particle, the more stable the suspension). (b) Non-ionic medium: charges on the barium sulphate particles influence the rate of aggregation of the particles. Aggregation is enhanced in the presence of the gastric contents. (c) Solution pH: suspension stability is best at pH 5.3. However, as the suspension passes through the stomach, it is inevitably acidified and tends to precipitate. The encapsulation of barium sulfate in microspheres of appropriate size provides a good separation of individual contrast elements and may, if the polymer displays bioadhesive properties, help in coating, preferentially, the gastric mucosa in the presence of excessive gastric fluid. With bioadhesiveness targeted to more distal segments of the gastrointestinal tract, it may also provide a kind of wall imaging not easily obtained otherwise. The double contrast technique, which utilizes both gas and barium sulphate to enhance the imaging process, especially requires a proper coating of the mucosal surface. To achieve a double contrast, air or carbon dioxide must be introduced. This is typically achieved via a nasogastric tube to provoke a controlled degree of gastric distension. Studies indicate that comparable results may be obtained by the release of individual gas bubbles in a large number of individual adhesive microspheres and that this imaging process may apply to intestinal segments beyond the stomach. An in vivo method for evaluating bioadhesion uses encapsulation of a radiopaque material, such as barium sulphate, or a gas-evolving agent, such as sodium carbonate, within a bioadhesive polymer. After oral administration of this radio-opaque material, its distribution in the gastric and intestinal areas is examined using image analysis. The present invention will be further understood by reference to the following non-limiting examples. EXAMPLE 1 Evaluation of Bioadhesive Properties of Polymeric Microspheres Polymers were evaluated for their bioadhesive potential using microspheres with diameters ranging from 700-800 μm and 700-2400 μm for the thermoplastics and hydrogels, respectively. The tensile type experiment used in this study offers several advantages over previous techniques. The setup enables one to determine bioadhesive forces between a single microsphere and intestinal mucosa. Since the experiment was conducted in an aqueous environment, problems in distinguishing between surface tension forces at the air/liquid interface and forces at the microsphere/mucus interface were eliminated. The results, shown in FIGS. 3 a , 3 b , and 3 c , demonstrate that polymers with higher concentrations of carboxylic acid groups such as alginate and polyanhydrides, produce greater bioadhesive bonds. The extremely high forces obtain for poly(fumaric-co-sebacic) anhydride (20:80) (50 mN/cm 2 ) indicate that bioerodible polymers are very promising bioadhesive delivery systems. The results also indicate that different fabrication methods which result in different morphologies exhibit different bioadhesive forces (e.g., PLA microspheres made by solvent evaporation adhere much stronger than PLA microspheres made by hot-melt microencapsulation). Comparison of the adhesive forces for polycarbophile, which was found to have good bioadhesive properties, show that polycarbophile displays bioadhesive forces of 1061 dyne/cm 2 (106.1 N/m 2 or 10.61 mN/cm 2 ) while most of the polymers described herein exhibit forces that range between 100 to 400 N/m 2 . EXAMPLE 2 Effect of Microsphere Diameter on Bioadhesive Forces. The effect of microsphere diameter on bioadhesive forces was investigated using P(CPP:SA) 20:80 and P(FA:SA) 20:80 microspheres ranging in size from 400 μm to 1700 μm, using the method described above. The results are shown in FIGS. 4 a , 4 b , 5 a , and 5 b . There was no decline in adhesive force with a decrease in microsphere diameter. To the contrary, the forces measured increase sharply as the diameters dropped below 750 μm to at least as low as 400 μm. EXAMPLE 3 In Vivo Transit Time Studies Using X-ray Imaging of Non-releasing Microspheres. A series of 10 rats were fed P(CPP-SA) 20:80 microspheres, as well as polystyrene microspheres, both loaded with barium sulphate. Each rat was fed 100 mg microspheres that were dispersed in 2 ml water. As controls, pure barium sulphate suspension in distilled water was fed to the rats. At given time intervals, the rats were X-rayed, and the distribution of the microspheres in the stomach and in the intestine was followed. The results are shown in FIGS. 6 and 7. It was observed that the polyanhydride and polystyrene microspheres were retained in the stomach for 11 to 16.5 hours while the barium sulphate was cleared from the stomach after 9 hours. Most of the barium sulphate was cleared from the intestine after 14 to 16 hours. Polystyrene microspheres were cleared from the gastrointestinal tract after the same time interval. However, it was observed that polyanhydride microspheres could still be found in the intestine even after 28 hours. Since normal transit time through the intestinal tract ranges between 4 to 12 hours, the results with polyanhydrides suggest bioadhesion of the microspheres which delays their passage through the gastrointestinal system. It is apparent that the smaller microspheres tend to have a longer retention time in the intestine. Comparing these results to the literature reveals that polycarbophiles with adhesive forces of 106 N/m 2 are retained 24 hr in the GI tract. Adhesive forces of about 200 N/m 2 yielded a retention time of 28 hr. Studies with microspheres containing barium sulfate demonstrated that some microspheres were retained in the gastrointestinal tract for as much as 28 hours. Using surface microscopy techniques, further analysis showed that the microspheres did tend to attach to the surface of the intestine. In a typical experiment, five rats were fed with polyanhydride microspheres made of poly[bis(p-carboxy phenoxy) propane-co-sebacic] (P[CPP-SA]) 20:80. The size of microspheres varied from 300 to 400 microns. 100 mg of spheres were suspended in 2 ml of distilled water and force-fed using a Gavage needle (gauge 16). Five hours after feeding, the rats were sacrificed by CO 2 asphyxiation and their intestines opened. Microspheres were found in the intestine, some sticking to the food, others adhering to the tissue. The areas with spheres adhering to the tissue were washed with saline. The tissue was fixed in neutral 10% formaldehyde solution for 24 hr. After fixation, the tissue was exposed to increasing concentrations of alcohol solutions, starting from 50:50% water and ethanol, and ending with 100% ethanol. At that stage, the tissue was dried using a CO 2 critical drying process. The dry samples were coated with gold-palladium and analyzed under a scanning electron microscope. A typical example of microspheres adhering to the intestine wall is shown in FIG. 8 . EXAMPLE 4 Preparation of Polyacrylamide Microspheres with High Bioadhesive Forces. Preparation of Microspheres. Polyacrylamide microspheres were produced by polymerizing an aqueous emulsion of acrylamide and bis methacrylamide in hexane. The following stock solutions were used: 1. 30% acrylamide (w/v), 10% bismethylacrylamide (w/v) in distilled water. The stock solution was treated with mixed bed ion-exchange resins to remove acrylic acid normally found in commercial preparations. 2. 1.2 M Tris pH 7.7. 3. 40% ammonium persulfate (w/v) 4. TEMED (N,N,N′,N′-Tetramethylethylenediamine 2 ml of the acrylamide stock, 1 ml of Tris stock, 0.1 ml of ammonium persulfate and 2 ml of distilled water to make a final volume of 5.1 ml of 12% acrylamide/4% bis methylacrylamide solution. This working solution was extensively degassed under water vacuum to remove dissolved oxygen which might inhibit the polymerization reaction. The acrylamide solution was added dropwise to 300 ml of n-hexane which was stirred at a rate of about 500 rpm with an overhead stirrer. Approximately 0.25 ml of SPAN 25 85 was added to the solution to prevent aggregation of the emulsion droplets. The stirring was generally maintained for 1-2 min until the emulsion reached the approximate desired size. To initiate polymerization, 1 ml of TEMED was added to the n-hexane phase and stirring was continued for 30 min. The beads were harvested and separated according to size by passing the solution through a series of graded sieves. Spheres having a diameter of between 300 and 800 μM were selected for further studies. EXAMPLE 5 Surface Activation of the Polyacrylamide Microspheres. Polyacrylamide microspheres were treated with 1 liter carbonyldimiazole (CDI) to covalently attach cation agents such as polyethyleneimine or poly-1-lysine. Typically one half-batch of the polyacrylamide beads were incubated with 0.5 M sodium carbonate for 1 hr at 60° C. with shaking. The sodium carbonate solution was changed twice with fresh solution during the incubation. This procedure is thought to hydrolyze the beads and produce free carboxyl groups which might be available for CDI reaction. Next the beads were solvent-exchanged with two changes of dry acetone and then incubated with 0.4% CDI (w/v) in acetone for 1 hr at 25° C. The incubation was repeated for an additional hour with fresh CDI solution. The beads were then washed twice with acetone to remove unbound CDI and then incubated with 10% polyethyleneimine (w/v), MW 1800) or else 1% poly-1-lysine in 0.2 M sodium borate buffer, pH 9.0 at 4° C. for 24 hrs. Alternatively, or in addition, one could add sialic acid to the polymer. The beads were washed twice with borate buffer and stored in 2 M ammonium chloride until needed. The ammonium chloride was used to inactivate “free” CDI binding sites. The beads were washed three times with 10 mM Tris, pH 7. immediately before use. Microspheres can be tested by the “Sprinkle Test” as follows. Microspheres are sprinkled over excised intestinal tissue segments. These segments were then placed in a buffer solution and left to incubate at 4° C. on a slowly moving shaker for 30 minutes. The samples were then analyzed with a dissecting stereo microscope. POLYMER COATING CAHN FORCE p(FA:SA) well coated approximately 26 mg polyacrylamide approximately 10 mg CDI/Polyacrylamide blanket of μspheres approximately 20 mg p(CPP:SA) scattered approximately 8 mg EXAMPLE 6 Comparative In Vitro Test of Bead Attachment to Rat Intestine Another way of comparing the relative bioadhesion capabilities of the microspheres was to incubate the different polymer particles with isolated rat intestine under physiological conditions. Typically, the jejunum from a newly sacrificed rat was removed, flushed with about 10 ml of Krebs Ringer saline, inverted on a stainless steel rod and divided into segments for testing. The segments were fashioned into empty sacs by attaching sutures to the cut ends. This step prevented the binding of microspheres to the serosal surface of the gut. The intestinal sacs were then incubated with a known number of microspheres of defined size range for a period of 30 min at 4° C. at shaking rate of about 30 r.p.m. At the end of the test period, the number of bead that attached to the intestine were counted as well as the number of unattached microspheres. The results of a typical experiment are described below. Polymer Attached Unattached Total P(CPP:SA) 24 261 285 P(FA:SA) 53 10 63 Acrylamid 113 220 330 CDI-Acryl 243 406 649 Polymer % Binding Sac Length Beads bound/cm sac P(CPP:SA) 8.4 3.0 cm 8 P(FA:SA) 84.1 4.8 cm 11 Acrylamide 33.9 2.8 cm 40 CDI-Acryl 37.4 4.1 cm 59 Modifications and variations of the method and bioadhesive microsphere compositions described herein will be obvious to those skilled in the art from the foregoing detailed description. Such modifications and variations are intended to come within the scope of the appended claims.

Bioadhesive polymers in the form of, or as a coating on, microcapsules containing drugs or bioactive substances which may serve for therapeutic, diagnostic, or diagnostic purposes in diseases of the gastrointestinal tract, are described. The polymeric microspheres all have a bioadhesive force of at least 11 mN/cm 2 (110 N/CM 2 ). Techniques for the fabrication of bioadhesive microspheres, as well as a method for measuring bioadhesive forces between microspheres and selected segments of the gastrointestinal tract in vitro are also described. This quantitative method provides a means to establish a correlation between the chemical nature, the surface morphology and the dimensions of drug-loaded microspheres on one hand and bioadhesive forces on the other, allowing the screening of the most promising materials from a relatively large group of natural and synthetic polymers which, from theoretical consideration, should be used for making bioadhesive microspheres.

CROSS REFERENCE TO RELATED APPLICATION The present U.S. Utility Patent Application claims priority under 35 U.S.C. §120, as a continuation of U.S. Utility patent application Ser. No. 12/537,495, filed Aug. 7, 2009, issuing as U.S. Pat. No. 8,275,423, which is incorporated herein by reference in its entirety for all purposes. The Ser. No. 12/537,495 application claims priority under 35 U.S.C. §120, as a continuation of U.S. Utility patent application Ser. No. 10/810,094, filed Mar. 26, 2004, now U.S. Pat. No. 7,583,985, which is incorporated herein by reference in its entirety for all purposes. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates in general to the field of data processing. In one aspect, the present invention relates to a method and system for reducing power consumption in a communications system. 2. Related Art In general, data processors are capable of executing a variety of instructions. Processors are used in a variety of applications, including communication systems formed with wireless and/or wire-lined communication devices. Such communication systems range from national and/or international cellular telephone systems to the Internet to point-to-point in-home wireless networks. Each type of communication system is constructed, and hence operates, in accordance with one or more communication standards. For instance, wireless communication systems may operate in accordance with one or more standards including, but not limited to, IEEE 802.11, Bluetooth, advanced mobile phone services (AMPS), digital amps, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS) and/or variations thereof. Especially with wireless and/or mobile communication devices (such as a cellular telephone, two-way radio, personal digital assistant (PDA), personal computer (PC), laptop computer, home entertainment equipment, etc.), the processor or processors in a device must be able to run various complex communication programs using only a limited amount of power that is provided by power supplies, such as batteries, contained within such devices. In particular, for a wireless communication device to participate in wireless communications, the device includes a built-in radio transceiver (i.e., receiver and transmitter) or is coupled to an associated radio transceiver (e.g., a station for in-home and/or in-building wireless communication networks, RF modem, etc.). To implement the transceiver function, one or more processors and other modules are used to form a transmitter which typically includes a data modulation stage, one or more intermediate frequency stages and a power amplifier. The data modulation stage converts raw data into baseband signals in accordance with a particular wireless communication standard. The intermediate frequency stages mix the baseband signals with one or more local oscillations to produce RF signals. Alternatively, in direct conversion transmitters/receivers, conversion directly between baseband signals and RF signals is performed. The power amplifier amplifies the RF signals prior to transmission via an antenna. In addition, one or more processors and other modules are used to form a receiver which is typically coupled to an antenna and includes a low noise amplifier, one or more intermediate frequency stages, a filtering stage and a data recovery stage. The low noise amplifier receives inbound RF signals via the antenna and amplifies them. The intermediate frequency stages mix the amplified RF signals with one or more local oscillations to convert the amplified RF signal into baseband signals or intermediate frequency (IF) signals. The filtering stage filters the baseband signals or the IF signals to attenuate unwanted out of band signals to produce filtered signals. The data recovery stage recovers raw data from the filtered signals in accordance with the particular wireless communication standard. Because of the computational intensity (and the associated power consumption by the processor(s)) for such transceiver functions, it is an important goal in the design of wireless and/or mobile communication devices to minimize processor and other module operations (and the associated power consumption). It is particularly crucial for mobile applications in order to extend battery life. The device must provide a high rate of data throughput when necessary, and otherwise enter a low power mode, called a sleep mode, where various modules are deactivated. Such a strategy can greatly decrease the system's average power consumption. With conventional solutions for saving power, a variety of complex circuit and hardware designs have been proposed. These mechanisms exhibit substantial latencies for entering and leaving sleep mode, which restricts the power that can be saved and the range of applicability because these latencies may preclude a processor from being able to deactivate modules before having to reactivate them. Moreover, these mechanisms are burdensome to use, requiring code routines such as an interrupt handler to evaluate and respond to the wake-up conditions. In addition, many implementations are based on complex signaling mechanisms and processor state transitions which require significant hardware and software support and also exhibit long latencies. In addition to the complexity of the computational requirements for a communications transceiver, such as described above, the ever-increasing need for higher speed communications systems imposes additional performance requirements and resulting costs for communications systems. In order to reduce costs, communications systems are increasingly implemented using Very Large Scale Integration (VLSI) techniques. The level of integration of communications systems is constantly increasing to take advantage of advances in integrated circuit manufacturing technology and the resulting cost reductions. This means that communications systems of higher and higher complexity are being implemented in a smaller and smaller number of integrated circuits. For reasons of cost and density of integration, the preferred technology is CMOS. To this end, digital signal processing (“DSP”) techniques generally allow higher levels of complexity and easier scaling to finer geometry technologies than analog techniques, as well as superior testability and manufacturability. Therefore, a need exists for a method and apparatus that provides reduced power consumption with smaller deactivation and/or activation latencies. In addition, a need exists for reducing processor power consumption without requiring complex hardware and elaborate signaling mechanisms. Moreover, a need exists for improved selectivity when determining the nature and extent of the required power-up operations. There is also a need for a better system that is capable of performing the above functions and overcoming these difficulties without increasing circuit area and operational power. Further limitations and disadvantages of conventional systems will become apparent to one of skill in the art after reviewing the remainder of the present application with reference to the drawings and detailed description which follow. SUMMARY OF THE INVENTION The present invention is directed to apparatus and methods of operation that are further described in the following Brief Description of the Drawings, the Detailed Description of the Invention, and the Claims. Other features and advantages of the present invention will become apparent from the following detailed description of the embodiments of the invention made with reference to the accompanying claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram of a wireless communication system in accordance with an exemplary embodiment of the present invention. FIG. 2 is a schematic block diagram of a wireless communication device in accordance with an exemplary embodiment of the present invention. FIG. 3 is a schematic block diagram of a wireless interface device in accordance with an exemplary embodiment of the present invention. FIG. 4 depicts an exemplary state machine description of an exemplary embodiment of the present invention. FIG. 5 depicts a methodology and program sequence for an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION A method and apparatus for an improved communications processor is described. While various details are set forth in the following description, it will be appreciated that the present invention may be practiced without these specific details. For example, selected aspects are shown in block diagram form, rather than in detail, in order to avoid obscuring the present invention. Some portions of the detailed descriptions provided herein are presented in terms of algorithms or operations on data within a computer memory. Such descriptions and representations are used by those skilled in the data processing arts to describe and convey the substance of their work to others skilled in the art. In general, an algorithm refers to a self-consistent sequence of steps leading to a desired result, where a “step” refers to a manipulation of physical quantities which may, though need not necessarily, take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It is common usage to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. These and similar terms may be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussion, it is appreciated that throughout the description, discussions using terms such as processing, computing, calculating, determining, displaying or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and/or transforms data represented as physical, electronic and/or magnetic quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. Broadly speaking, the present invention provides an improved method and system for controlling the sleep and wake-up modes of a processor. Using a PSM (programmable state machine) in the MAC layer of a communications processor, the processor and associated modules may be quickly powered down and efficiently reactivated by powering up only the processor and the required modules necessary to respond to the asserted wake-up conditions. This may be accomplished by issuing a wake-up signal only when specified wake-up conditions are detected, and then only reactivating the necessary components to respond to the wake-up signal. With this approach, a staged wake-up is provided for improved power management with reduced latencies. In accordance with various embodiments of the present invention, a method and apparatus provides a power saving mechanism for a programmable communications processor. The power saving mechanism may be implemented using the MAC layer programming to control the sleep and wake-up modes and to provide for a staged wake-up of various processor modules for improved power management. The host processor may also be subject to this power management. The PSM invokes the power saving mechanism by specifying wake-up conditions and a sleep time-out period, and then executing a sleep instruction until a wake-up condition is detected or the time-out period expires, at which time the wake-up condition is processed to determine what specific circuitry or modules need to be reactivated. In a selected embodiment power control logic is provided for directly awakening some modules, while other modules are awakened by the PSM's instruction once the PSM reawakens. Thus, the present invention provides improved effectiveness, reduced latency, simplified programming and reduced hardware overhead. FIG. 1 illustrates a wireless communication system 10 in which embodiments of the present invention may operate. As illustrated, the wireless communication system 10 includes a plurality of base stations and/or access points 12 , 16 , a plurality of wireless communication devices 18 - 32 and a network hardware component 34 . The wireless communication devices 18 - 32 may be laptop host computers 18 , 26 , personal digital assistant hosts 20 , 30 , personal computer hosts 32 , cellular telephone hosts 28 and/or wireless keyboards, mouse devices or other Bluetooth devices 22 , 24 . The details of the wireless communication devices will be described in greater detail with reference to FIGS. 2-5 . As illustrated, the base stations or access points 12 , 16 are operably coupled to the network hardware 34 via local area network connections 36 , 38 . The network hardware 34 (which may be a router, switch, bridge, modem, system controller, etc.) provides a wide area network connection 42 for the communication system 10 . Each of the base stations or access points 12 , 16 has an associated antenna or antenna array to communicate with the wireless communication devices in its area. Typically, the wireless communication devices register with a particular base station or access point 12 , 16 to receive services from the communication system 10 . For direct connections (e.g., point-to-point communications between laptop 26 and mouse or keyboard 22 ), wireless communication devices communicate directly via an allocated channel. Regardless of the particular type of communication system, each wireless communication device includes a built-in radio and/or is coupled to a radio. The radio includes a highly linear amplifier and/or programmable multi-stage amplifier with a low latency power saving mechanism as disclosed herein to enhance performance, reduce costs, reduce size, reduce power consumption and/or enhance broadband applications. FIG. 2 is a schematic block diagram illustrating a radio implemented in a wireless communication device that includes the host device or module 50 and at least one wireless interface device, or radio transceiver 59 . The wireless interface device may be built in components of the host device 50 or externally coupled components. As illustrated, the host device 50 includes a processing module 51 , memory 52 , peripheral interface 55 , input interface 58 and output interface 56 . The processing module 51 and memory 52 execute the corresponding instructions that are typically done by the host device. For example, in a cellular telephone device, the processing module 51 performs the corresponding communication functions in accordance with a particular cellular telephone standard. The wireless interface device 59 includes a host interface, a media-specific access control protocol (MAC) layer module, a physical layer module (PHY), a digital-to-analog converter (DAC), and an analog to digital converter (ADC). The peripheral interface 55 allows data to be received from and sent to one or more external devices 65 via the wireless interface device 59 . As will be appreciated, the modules in the wireless interface device are implemented with a communications processor and an associated memory for storing and executing instructions that control the access to the physical transmission medium in the wireless network. Each external device includes its own wireless interface device for communicating with the wireless interface device of the host device. For example, the host device may be personal or laptop computer and the external device 65 may be a headset, personal digital assistant, cellular telephone, printer, fax machine, joystick, keyboard, desktop telephone, or access point of a wireless local area network. In this example, external device 65 is an IEEE 802.11 wireless interface device. FIG. 3 is a schematic block diagram of a wireless interface device (i.e., a radio) 60 which includes a host interface 62 , digital receiver processing module 64 , an analog-to-digital converter (ADC) 66 , a filtering/gain module 68 , a down-conversion stage 70 , a receiver filter 71 , a low noise amplifier 72 , a transmitter/receiver switch 73 , a local oscillation module 74 , memory 75 , a digital transmitter processing module 76 , a digital-to-analog converter (DAC) 78 , a filtering/gain module 80 , a mixing up-conversion stage 82 , a power amplifier 84 , and a transmitter filter module 85 . The transmitter/receiver switch 73 is coupled to the antenna 87 , which may include two antennas coupled through a switch. Still further, the antenna section 61 may include separate multiple antennas 87 a , 87 b for the transmit path and the receive path of each wireless interface device (as shown in FIG. 3 ). As will be appreciated, the antenna(s) may be polarized, directional, and be physically separated to provide a minimal amount of interference. The digital receiver processing module 64 , the digital transmitter processing module 76 and the memory 75 may execute digital receiver functions and digital transmitter functions in accordance with a particular wireless communication standard. The digital receiver functions include, but are not limited to, digital frequency conversion, demodulation, constellation demapping, decoding and/or descrambling. The digital transmitter functions include, but are not limited to, scrambling, encoding, constellation mapping, modulation and/or digital frequency conversion. The digital receiver and transmitter processing modules 64 , 76 may be implemented using a shared processing device, individual processing devices, or a plurality of processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry and/or any device that manipulates signals (analog and/or digital) based on operational instructions. The memory 75 may be a single memory device or a plurality of memory devices. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, and/or any device that stores digital information. Note that when the processing module 64 , 76 implements one or more of its functions via a state machine, analog circuitry, digital circuitry and/or logic circuitry, the memory storing the corresponding operational instructions may be embedded with the circuitry comprising the state machine, analog circuitry, digital circuitry and/or logic circuitry. In operation, the wireless interface device 60 receives outbound data 94 from the host device via the host interface 62 . The host interface 62 routes the outbound data 94 to the digital transmitter processing module 76 , which processes the outbound data 94 to produce digital transmission formatted data 96 in accordance with a particular wireless communication standard, such as IEEE 802.11 (including all current and future subsections), Bluetooth, etc. The digital transmission formatted data 96 will be a digital base-band signal or a digital low IF signal, where the low IF typically will be in the frequency range of one hundred kilohertz to a few megahertz. Subsequent stages convert the digital transmission formatted data to an RF signal, and may be implemented as follows. The digital-to-analog converter 78 converts the digital transmission formatted data 96 from the digital domain to the analog domain. The filtering/gain module 80 filters and/or adjusts the gain of the analog signal prior to providing it to the up-conversion module 82 . The mixing stage 82 directly converts the analog baseband or low IF signal into an RF signal based on a transmitter local oscillation clock 83 provided by local oscillation module 74 . The power amplifier 84 amplifies the RF signal to produce outbound RF signal 98 , which is filtered by the transmitter filter module 85 . The antenna section 61 transmits the outbound RF signal 98 to a targeted device such as a base station, an access point and/or another wireless communication device. The wireless interface device 60 also receives an inbound RF signal 88 via the antenna section 61 , which was transmitted by a base station, an access point, or another wireless communication device. The inbound RF signal is converted into digital reception formatted data; this conversion may be implemented as follows. The antenna section 61 provides the inbound RF signal 88 to the receiver filter module 71 via the transmit/receive switch 73 , where the receiver filter 71 bandpass filters the inbound RF signal 88 . The receiver filter 71 provides the filtered RF signal to low noise amplifier 72 , which amplifies the signal 88 to produce an amplified inbound RF signal. The low noise amplifier 72 provides the amplified inbound RF signal to the mixing module 70 , which directly converts the amplified inbound RF signal into an inbound low IF signal or baseband signal based on a receiver local oscillation clock 81 provided by local oscillation module 74 . The down conversion module 70 provides the inbound low IF signal or baseband signal to the filtering/gain module 68 . The filtering/gain module 68 filters and/or gains the inbound low IF signal or the inbound baseband signal to produce a filtered inbound signal. The analog-to-digital converter 66 converts the filtered inbound signal from the analog domain to the digital domain to produce digital reception formatted data 90 . The digital receiver processing module 64 decodes, descrambles, demaps, and/or demodulates the digital reception formatted data 90 to recapture inbound data 92 in accordance with the particular wireless communication standard being implemented by wireless interface device. The host interface 62 provides the recaptured inbound data 92 to the host device (e.g., 50 ) via the peripheral interface (e.g., 55 ). As will be appreciated, the wireless communication device of FIG. 2 described herein may be implemented using one or more integrated circuits. For example, the host device 50 may be implemented on one integrated circuit, the digital receiver processing module 64 , the digital transmitter processing module 76 and memory 75 may be implemented on a second integrated circuit, and the remaining components of the wireless interface device 60 and/or antenna 61 , may be implemented on a third integrated circuit. As an alternate example, the wireless interface device 60 may be implemented on a single integrated circuit. As yet another example, the processing module 51 of the host device and the digital receiver and transmitter processing modules 64 and 76 may be a common processing device implemented on a single integrated circuit. Further, the memory 52 and memory 75 may be implemented on a single integrated circuit and/or on the same integrated circuit as the common processing modules of processing module 51 and the digital receiver and transmitter processing module 64 and 76 . In a selected embodiment, the present invention shows, for the first time, a fully integrated, single chip 802.11b/g solution with built-in power management that reduces power consumption using an intelligent stand-by mode to provide greatly extended battery life for mobile devices, all implemented in CMOS (Complementary Metal Oxide Semiconductor), as part of a single chip or multi-chip transceiver radio. As for the processor componentry of the wireless interface device or radio, an exemplary depiction of the processor details is illustrated in FIG. 3 as communication processor 100 , which shows a system level description of the operation of an embodiment of a communication processor embodiment of the present invention. The communication processor 100 may be an integrated circuit or it may be constructed from discrete components. The communication processor 100 may implement a MAC module using a programmable state machine 102 (which includes the Fetch 141 , Decode 143 , Read 145 , Execute 147 and Write 149 pipeline, in that order). The processor 100 also includes a memory 118 , which may be implemented as a data RAM memory and code EPROM memory. Also included in the processor are the transmit/receive queues and supporting hardware 182 (coupled between host interface 181 and PHY interface 183 ), which may include transmit and receive queues, encryption modules, transmit and receive engines and/or packet processing hardware. For power management of the processor 100 , power-management logic 172 is provided, including the wake-up timer 134 , logic to select wake-up conditions, and logic to direct modules to deactivate themselves. To reduce the power consumed by processor-related circuits, the present invention provides a power management scheme to extend the battery life of Wi-Fi enabled small mobile devices. In a selected embodiment, the power management scheme uses a software approach to place the transceiver in standby mode and to selectively respond to wake-up commands, thereby reducing power consumption significantly without imposing a performance cost. In mobile device applications, the communications processor is able to spend a majority of its time in standby mode, adding several days of battery life to a PDA. In a selected embodiment illustrated in FIG. 3 , power management may be implemented using a wake-up timer 134 and a one or more specified wake-up conditions. The processor 100 may include instruction decode logic and branch condition logic that is configured to detect a sleep instruction and to respond to the wake-up conditions or the timer 134 . Once the communications processor 100 completes a high throughput task and/or receives a sleep instruction, the processor 100 prepares to enter sleep mode by specifying a set of conditions that will re-awaken it. The processor 100 then deactivates as many modules as possible. Some deactivations may occur prior to executing the sleep instruction. Once the sleep instruction has entered the instruction pipeline 140 and the preceding instructions in the pipeline have been completed, the remaining nonessential modules (such as the transmit/receive queues and major portions of the programmable state machine, etc.) are powered-down by either freezing their clocks or placing them in an idle mode. When one of the specified conditions is detected, the processor wakes up, analyzes the condition, and reactivates whatever modules are needed to service the condition. As illustrated in FIG. 4 , the sleep and wake-up modes described herein may be controlled by a programmable state machine (PSM) in the MAC layer of a communications processor, whereby the processor and associated modules may be quickly powered down and efficiently reactivated by powering up only the processor and those modules needed to respond to a communications or host related event. In particular, a processor that is fully or partially active and executing instructions (state 402 ) executes a power management program (transition 403 ) which specifies the wake-up conditions to which it will respond, along with a time-out period, any one of which will be used to generate a wake-up signal (state 404 ). The processor subsequently receives a sleep instruction (transition 405 ) and changes to a power down state 406 . In the power down state 406 , the processor and some associated modules are also placed in a sleep mode by disabling power and/or clock signals to the processor modules or otherwise idling the modules. Upon receipt of a wake-up signal (transition 407 ), a selective reactivation state is entered (state 408 ), whereby the required processor componentry and/or modules are powered-up based upon the detected wake-up condition. The processor then begins processing the wake-up signal and its associated wake-up condition(s) to proceed (via transition 409 ) to the fully or partially active instruction execution state (state 402 ), where the required modules are used to execute the instruction(s) corresponding to the detected wake-up condition. In a selected embodiment, when the PSM wakes up, all of the instruction pipeline stages also wake up to permit the instruction to flow from stage to stage, progressing through fetch/decode, read, execute, and write. FIG. 5 depicts an exemplary power saving methodology and program sequence for the present invention. As an initial step, after having completed any previous communication tasks, the processor 100 specifies the wake-up conditions that will be used to wake up the processor, along with a time-out period, at step 502 . For example, the conditions to observe and the wake-up interval may be specified by registers which are loaded by a power saving program. The processor may then deactivate certain nonessential modules, at step 503 . In a selected embodiment, these modules are those whose deactivation is controlled by the processor's instructions. With step 503 , the PSM's instructions power down some modules (generally by writing appropriate values into the modules' control registers) prior to the PSM's execution of the sleep instruction. The processor detects and executes a sleep instruction at step 504 . This sleep instruction detection functionality may be implemented by control logic in the processor 100 . In one implementation, the instruction decode logic in the processor 100 may be extended to detect the sleep instruction (step 504 ). Upon receipt of a sleep instruction, the processor logic determines that preceding instructions in the pipeline 140 have completed (step 506 ) prior to deactivation. Upon completion of the pending instructions from the pipeline, the processor and its associated modules enter a sleep or standby mode at step 508 . In a selected embodiment, if a sleep instruction is encountered (decision 504 ) when the specified wake-up conditions are deasserted, the control logic will cease fetching new instructions, wait until any preceding instructions are finished (step 506 ), and then cause the processor to enter a dormant, low-power state (step 508 ). The low-power state may be implemented by disabling the clocks for one or more processor modules. In a selected embodiment, these modules are those whose deactivation is directly controlled by the processor's hardware. For any processor modules which require clocks in order to provide data for external devices, these modules may be directed to enter an idle mode. Once the processor is powered down or in standby mode, when one of the specified conditions occurs or if the wake-up interval is reached (detection step 510 ), the wake-up signal asserts. In a selected implementation, branch condition logic in the processor may be expanded to select multiple conditions and logically OR them together—along with the wake-up timer's output—to form a wake-up signal. At step 512 , the wake-up signal is issued to the processor. In a selected embodiment, the wake-up signal is supplied to the control logic which reactivates instruction pipeline 140 to begin fetching the next instruction after the sleep instruction (step 514 ). Subsequent stages of the pipeline are reactivated as this instruction and those that follow are processed. At step 516 , the instructions following the sleep instruction are executed by processor 100 to analyze the asserted wake-up conditions and reactivate the modules that are needed to respond to the wake-up condition (step 518 ). Rather than reactivating the entire processor and associated modules, the present invention allows for judicious use of power upon wake-up by reactivating only the modules that are needed to service the wake-up condition. Upon completing the required communications tasks, the processor may then specify another set of wake-up conditions and a time-out interval, prior to executing an associated sleep instruction. Optionally, the processor may loop back and repeat some or all of the outlined procedure using the specified wake-up conditions and time-out interval. With the power saving mechanism of the present invention, the deactivation and re-activation latencies may be reduced significantly as compared to conventional hardware-based techniques involving an interrupt handler to facilitate these tasks. Such conventional techniques require elaborate signaling mechanisms and processor state transitions that impose long latencies. Such latencies greatly restrict the amount of power that can be saved as well as the range of situations where modules can be powered-down. In contrast, an implementation of the present invention relies on a sleep instruction along with logic to decode it and respond appropriately, including selection of wake-up signals and a time-out interval, which quickly and efficiently enables selective reactivation of only the processor modules that are required to service the specified wake-up condition, thereby applying only power that is needed to service the wake-up conditions. In particular, effective power saving is obtained by deactivating all instruction pipeline stages (instruction fetch, instruction decode and operand read, execution, and write) and other external modules, and then selectively reactivating only the modules needed to service the wake-up condition. A power saving program embodiment provides low latency standby mode to reduce power consumption with minimum delay, and allows its application to a wide range of situations, including those where high throughput and idle intervals alternate in close proximity. From the programmer's perspective, the power saving mechanism of the present invention is simple to use, requiring specification of wake-up conditions and a wake-up interval and then a single sleep instruction. Little additional program memory is needed for these instructions. From a hardware perspective, the overhead is relatively low with only minor extensions being needed with regard to the instruction decode and branch condition logic, as well as the addition of a count-down timer. As described herein and claimed below, a method and apparatus are provided for controlling the sleep and wake-up modes of a processor. Using a PSM (programmable state machine) in the MAC layer of a communications processor, the processor and associated modules may be quickly powered down and efficiently reactivated by powering up only the processor and those modules needed to respond to a communications event. This translates to a very power efficient processor. As will be appreciated, the present invention may be implemented in a computer accessible medium including one or more data structures representative of the circuitry included in the system described herein. Generally speaking, a computer accessible medium may include storage media such as magnetic or optical media, e.g., disk, CD-ROM, or DVD-ROM, volatile or non-volatile memory media such as RAM (e.g., SDRAM, RDRAM, SRAM, etc.), ROM, PROM, EPROM, EEPROM, etc. For example, data structure(s) of the circuitry on the computer accessible medium may be read by a program and used, directly or indirectly, to implement the hardware comprising the circuitry described herein. For example, the data structure(s) may include one or more behavioral-level descriptions or register-transfer level (RTL) descriptions of the hardware functionality in a high level design language (HDL) such as Verilog or VHDL. The description(s) may be read by a synthesis tool which may synthesize the description to produce one or more netlist(s) comprising lists of gates from a synthesis library. The netlist(s) comprise a set of gates which also represent the functionality of the hardware comprising the circuitry. The netlist(s) may then be placed and routed to produce one or more data set(s) describing geometric shapes to be applied to masks. The masks may then be used in various semiconductor fabrication steps to produce a semiconductor circuit or circuits corresponding to the circuitry. Alternatively, the data structure(s) on computer accessible medium may be the netlist(s) (with or without the synthesis library) or the data set(s), as desired. In yet another alternative, the data structures may comprise the output of a schematic program, or netlist(s) or data set(s) derived therefrom. While a computer accessible medium may include a representation of the present invention, other embodiments may include a representation of any portion of the power management system and/or the PSM, memory, supporting hardware modules and power-down logic. While the system and method of the present invention has been described in connection with the preferred embodiment, it is not intended to limit the invention to the particular form set forth, but on the contrary, is intended to cover such alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims so that those skilled in the art should understand that they can make various changes, substitutions and alterations without departing from the spirit and scope of the invention in its broadest form.

A power management scheme for a wireless communications device processor substantially implemented on a single CMOS integrated circuit is described. By incorporating controls for sleep and wake-up mode transitions in the processor's control logic, improved power savings with reduced latency is provided, obviating the need for hardware-focused solutions with elaborate signaling mechanisms. A fully integrated power management with staged wake-up operations controlled by the MAC solution consumes less power than the conventional wireless LAN solutions in standby mode.

CROSS-REFERENCE TO PRIOR PROVISIONAL APPLICATION [0001] This application claims the benefit of U.S. Provisional Application No. 60/093,421, filed Jul. 20, 1998 BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to a fluidic medical diagnostic device for measuring the concentration of an analyte in or a property of a biological fluid. [0004] 2. Description of the Related Art [0005] A variety of medical diagnostic procedures involve tests on biological fluids, such as blood, urine, or saliva, and are based on a change in a physical characteristic of such a fluid or an element of the fluid, such as blood serum. The characteristic can be an electrical, magnetic, fluidic, or optical property. When as optical property is monitored, these procedures may make use of a transparent or translucent device to contain the biological fluid and a reagent. A change in light absorption of the fluid can be related to an analyte concentration in, or property of, the fluid. Typically, a light source is located adjacent to one surface of the device and a detector is adjacent to the opposite surface. The detector measures light transmitted through a fluid sample. Alternatively, the light source and detector can be on the same side of the device, in which case the detector measures light scattered and/or reflected by the sample. Finally, a reflector may be located at or adjacent to the opposite surface. A device of this latter type, in which light is first transmitted through the sample area, then reflected through a second time, is called a “transflectance” device. References to “light” throughout this specification and the appended claims should be understood to include the infrared and ultraviolet spectra, as well as the visible. References to “absorption” are meant to refer to the reduction in intensity as a light beam passes through a medium; thus, it encompasses both “true” absorption and scattering. [0006] An example of a transparent test device is described in Wells et al. WO94/02850, published on Feb. 3, 1994. Their device comprises a sealed housing, which is transparent or translucent, impervious, and rigid or semi-rigid. An assay material is contained within the housing, together with one or more assay reagents at predetermined sites. The housing is opened and the sample introduced just before conducting the assay. The combination of assay reagents and analyte in the sample results in a change in optical properties, such as color, of selected reagents at the end of the assay. The results can be read visually or with an optical instrument. [0007] U.S. Pat. No. 3,620,676, issued on Nov. 16, 1971 to Davis, discloses a calorimetric indicator for liquids. The indicator includes a “half-bulb cavity”; which is compressible. The bulb is compressed and released to form a suction that draws fluid from a source, through a half-tubular cavity that has an indicator imprinted on its wall. The only controls on fluid flow into the indicator are how much the bulb is compressed and how long the indicator inlet is immersed in the source, while the bulb is released. [0008] U.S. Pat. No. 3,640,267, issued on Feb. 8, 1972 to Hurtig et al., discloses a container for collecting Kilo samples of body fluid that includes a chamber that has resilient, collapsible walls. The walls are squeezed before the container inlet is placed into the fluid being collected. When released, the walls are restored to their uncollapsed condition, drawing fluid into and through the inlet. As with the Davis device, discussed above, control of fluid flow into the indicator is very limited. [0009] U.S. Pat. No. 4,088,448, issued on May 9, 1978 to Lilja et al., discloses a cuvette, which permits optical analysis of a sample mixed with a reagent. The-reagent is coated on the walls of a cavity, which is then filled with a liquid sample. The sample mixes with the reagent to cause an optically-detectable change. [0010] A number of patents, discussed below, disclose devices for diluting and/or analyzing biological fluid samples. These devices include valve-like designs to control the flow of the sample. [0011] U.S. Pat. No. 4,426,451, issued on Jan. 17, 1984 to Columbus, discloses a multi-zone fluidic device that has pressure-actuatable means for controlling the flow of fluid between the zones. His device makes use of pressure balances on a liquid meniscus at the interface between a first zone and a second zone that has a different cross section. When both the first and second zones are at atmospheric pressure, surface tension creates a back pressure that stops the liquid meniscus from proceeding from the first zone to the second. The configuration of this interface or “stop junction” is such that the liquid flows into the second zone only upon application of an externally generated pressure to the liquid in the first zone that is sufficient to push the meniscus into the second zone. [0012] U.S. Pat. No. 4,868,129, issued on Sep. 19, 1989 to Gibbons et al., discloses that the back pressure in a stop junction can be overcome by hydrostatic pressure on the liquid in the first zone, for example by having a column of fluid in the first zone. [0013] U.S. Pat. No. 5,230,866, issued on Jul. 27, 1993 to Shartle et al., discloses a fluidic device with multiple stop junctions in which the surface tension-induced back pressure at the stop junction is augmented; for example, by trapping and compressing gas in the second zone. The compressed gas can then be vented before applying additional hydrostatic pressure to the first zone to cause fluid to flow into the second zone. By varying the back pressure of multiple stop junctions in parallel, “rupture junctions” can be formed, having lower maximum back pressure. [0014] U.S. Pat. No. 5,472,603, issued on Dec. 5, 1995 to Schembri (see also U.S. Pat. No. 5,627,041), discloses using centrifugal force to overcome the back pressure in a stop junction. When flow stops, the first zone is at atmospheric pressure plus a centrifugally generated pressure that is less than the pressure required to overcome the back pressure. The second zone is at atmospheric pressure. To resume flow, additional centrifugal pressure is applied to the first zone, overcoming the meniscus back pressure. The second zone remains at atmospheric pressure. [0015] European Patent Application EP 0,803,288, of Naka et al., published on Oct. 29, 1997, discloses a device and method for analyzing a sample that includes drawing the sample into the device by suction, then reacting the sample with a reagent in an analytical section. Analysis is done by optical or electrochemical means. In alternate embodiments, there are multiple analytical sections and/or a bypass channel. The flow among these sections is balanced without using stop junctions. [0016] U.S. Pat. No. 5,700,695, issued on Dec. 23, 1997 to Yassinzadeh et al., discloses an apparatus for collecting and manipulating a biological fluid that uses a “thermal pressure chamber” to provide the driving force for moving the sample through the apparatus. [0017] U.S. Pat. No. 5,736,404, issued on Apr. 7, 1998, to Yassinzadeh et al., discloses a method for determining the coagulation time of a blood sample that involves causing an end of the sample to oscillate within a passageway. The oscillating motion is caused by alternately increasing and decreasing the pressure on the sample. SUMMARY OF THE INVENTION [0018] The present invention provides a fluidic diagnostic device for measuring an analyte concentration or property of a biological fluid. The device comprises a first layer and second layer at least one of which has a resilient region over at least part of its area, separated by an intermediate layer, in which cutouts in the intermediate layer form, with the first and second layers, [0019] a) a sample port for introducing a sample of the biological fluid into the device; [0020] b) a first measurement area, in which a physical parameter of the sample is measured and related to the analyte concentration or property of the fluid; [0021] c) a first channel, having a first end and a second end, to provide a fluidic path from the sample port at the first end through the first measurement area; [0022] d) a first bladder at the second end of the first channel, comprising at least a part of the resilient region in at least the first or second layer and having a volume that is at least about equal to the combined volume of the first measurement area and first channel; and [0023] e) a first stop junction in the first channel between the first measurement area and first bladder that comprises a co-aligned through hole in at least the first or second layer, the through hole being overlaid with a third layer. [0024] In another embodiment, the device comprises [0025] a first layer, which has a resilient region over at least a part of its area, and a second layer, separated by an intermediate layer, in which recesses in a first surface of the intermediate layer form, with the first layer, [0026] a) a sample port for introducing a sample of the biological fluid into the device; [0027] b) a measurement area, in which the sample undergoes a change in a physical parameter that is measured and related to the analyte concentration or property of the fluid; [0028] c) a channel, having a first end and a second end, to provide a fluidic path from the sample port at the first end through the measurement area; and [0029] d) a bladder, at the second end of the channel, comprising at least a part of the resilient region in the first layer and having a volume that is at least about equal to the combined volume of the measurement area and channel; and [0030] a stop junction in the channel between the measurement area and bladder that comprises two passages substantially normal to the first surface of the intermediate layer, each passage having a first end in fluid communication with the channel and a second end in fluid communication with a recess in a second surface of the intermediate layer, which recess provides fluid communication between the second ends of the passages. [0031] The device is particularly well adapted for measuring prothrombin time (PT time), with the biological fluid being whole blood and the measurement area having a composition that catalyzes the blood clotting cascade. BRIEF DESCRIPTION OF THE DRAWINGS [0032] [0032]FIG. 1 is a plan view of a device of the present invention. [0033] [0033]FIG. 2 is an exploded view of the device of FIG. 1. [0034] [0034]FIG. 3 is a perspective view of the device of FIG. 1. [0035] [0035]FIG. 4 is a schematic of a meter for use with a device of this invention. [0036] [0036]FIG. 4A depicts an alternative embodiment of an element of the meter of FIG. 4. [0037] [0037]FIG. 5 is a graph of data that is used to determine PT time. [0038] [0038]FIG. 6 is a plan view of an alternative embodiment of a device of this invention. [0039] [0039]FIGS. 6A, 6B, and 6 C depict a time sequence during which a sample is admitted to the device of FIG. 6. [0040] [0040]FIG. 7 is a schematic of a device having multiple measurement areas in parallel, multiple stop junctions in parallel, and a single bladder. [0041] [0041]FIG. 8 is a schematic of a device having multiple measurement areas in series, with a single stop junction, a single bladder, and a filter over the sample port. [0042] [0042]FIG. 9 is a schematic of a device having multiple measurement areas and multiple stop junctions arranged in an alternating series, as well as multiple bladders. [0043] [0043]FIG. 10 is a schematic of a device that includes multiple measurement areas in parallel, a single bladder, and a single bypass channel. [0044] [0044]FIG. 11 is a schematic of a device having multiple measurement areas in series, multiple stop junctions in series, multiple-bladders in series, and multiple bypass channels. [0045] [0045]FIG. 12 is an exploded view of an injection-molded device of this invention. [0046] [0046]FIG. 13 is a perspective view of the device of FIG. 12. DETAILED DESCRIPTION OF THE INVENTION [0047] This invention relates to a fluidic device for analyzing biological fluid. The device is of the type that relates a physical parameter of the fluid, or an element of the fluid, to an analyte concentration in the fluid or to a property of the fluid. Although a variety of physical parameters—e.g., electrical, magnetic, fluidic, or optical—can form the basis for the measurement, a change in optical parameters is a preferred basis, and the details that follow refer to an optical device. The device includes a sample application area; a bladder, to create a suction force to draw the sample into the device; a measurement area, in which the sample may undergo a change in an optical parameter, such as light scattering; and a stop junction to precisely stop flow after filling the measurement area. [0048] Preferably, the device is substantially transparent over the measurement area, so that the area can be illuminated by a light source on one side and the transmitted light measured on the opposite side. The measurement on the sample may be of a parameter that is not changing, but typically the sample undergoes a change in the measurement area, and the change in transmitted light is a measure of the analyte or fluid property of interest. Alternatively, light that is scattered from a fluid sample or light that passes through the sample and is reflected back through a second time (by a reflector on that opposite side) can be detected by a detector on the same side as the light source. [0049] This type of device is suitable for a variety of analytical tests of biological fluids, such as determining biochemical or hematological characteristics, or measuring the concentration in such fluids of proteins, hormones, carbohydrates, lipids, drugs, toxins, gases, electrolytes, etc. The procedures for performing these tests have been described in the literature. Among the tests, and where they are described, are the following: [0050] (1) Chromogenic Factor XIIa Assay (and other clotting factors as well): Rand, M. D. et al., Blood, 88 , 3432 (1996). [0051] (2) Factor X Assay: Bick, R. L. Disorders of Thrombosis and Hemostasis: Clinical and Laboratory Practice. Chicago, ASCP Press, 1992. [0052] (3) DRVVT (Dilute Russells Viper Venom Test): Exner, T. et al., Blood Coag. Fibrinol., 1, 259 (1990). [0053] (4) Immunonephelometric and Immunoturbidimetric Assays for Proteins: Whicher, J. T., CRC Crit. Rev. Clin Lab Sci. 18:213 (1983). [0054] (5) TPA Assay: Mann, K. G., et al., Blood, 76, 755, (1990).; and Hartshorn, J. N. et al., Blood, 78, 833 (1991). [0055] (6) APTT (Activated Partial Thromboplastin Time Assay): Proctor, R. R. and Rapaport, S. I. Amer. J. Clin. Path, 36, 212 (1961); Brandt, J. T. and Triplett, D. A. Amer. J. Clin. Path., 76, 530 (1981); and Kelsey, P. R. Thromb. Haemost. 52, 172 (1984). [0056] (7) HbAlc Assay (Glycosylated Hemoglobin Assay): Nicol, D. J. et al., Clin. Chem. 29, 1694 (1983). [0057] (8) Total Hemoglobin: Schneck et al., Clinical Chem., 32/33, 526 (1986); and U.S. Pat. No. 4,088,448. [0058] (9) Factor Xa: Vinazzer, H., Proc. Symp. Dtsch. Ges. Klin. Chem., 203 (1977), ed. By Witt, I [0059] (10) Colorimetric Assay for Nitric Oxide: Schmidt, H. H., et al., Biochemica, 2, 22,(1995). [0060] The present device is particularly well suited for measuring blood-clotting time—“prothrombin time” or “PT time”—and details regarding such a device appear below. The modifications needed to adapt the device for applications such as those listed above require no more than routine experimentation. [0061] [0061]FIG. 1 is a plan view of a device 10 of the present invention. FIG. 2 is an exploded view and FIG. 3 a perspective view of the device. Sample is applied to sample port 12 after bladder 14 has been compressed. Clearly, the region of layer 26 and/or layer 28 that adjoins the cutout for bladder 14 must be resilient, to permit bladder 14 to be compressed. Polyester of about 0.1 mm thickness has suitable resilience and springiness. Preferably, top layer 26 has a thickness of about 0.125 mm, bottom layer 28 about 0.100 mm. When the bladder is released, suction draws sample through channel 16 to measurement area 18 , which preferably contains a reagent 20 . In order to ensure that measurement area 18 can be filled with sample, the volume of bladder 14 is preferably at least about equal to the combined volume of channel 16 and measurement area 18 . If measurement area 18 is to be illuminated from below, layer 28 must be transparent where it adjoins measurement area 18 . For a PT test, reagent 20 contains thromboplastin that is free of bulking reagents normally found in lyophilized reagents. [0062] As shown in FIGS. 1, 2, and 3 , stop junction 22 adjoins bladder 14 and measurement area 18 ; however, a continuation of channel 16 may be on either or both sides of stop junction 22 , separating the stop junction from measurement area 18 and/or bladder 14 . When the sample reaches stop junction 22 , sample flow stops. For PT measurements, it is important to stop the flow of sample as it reaches that point to permit reproducible “rouleaux formation”—the stacking of red blood cells—which is an important step in monitoring blood clotting using the present invention. The principle of operation of stop junctions is described in U.S. Pat. No. 5,230,866, incorporated herein by reference. [0063] As shown in FIG. 2, all the above elements are formed by cutouts in intermediate layer 24 , sandwiched between top layer 26 and bottom layer 28 . Preferably, layer 24 is double-sided adhesive tape. Stop junction 22 is formed by an additional cutout in layer 26 and/or 28 , aligned with the cutout in layer 24 and sealed with sealing layer 30 and/or 32 . Preferably, as shown, the stop junction comprises cutouts in both layers 26 and 28 , with sealing layers 30 and 32 . Each cutout for stop junction 22 is at as least as wide as channel 16 . Also shown in FIG. 2 is an optional filter 12 A to cover sample port 12 . The filter may separate out red blood cells from a whole blood sample and/or may contain a reagent to interact with the blood to provide additional information. A suitable filter comprises an anisotropic membrane, preferably a polysulfone membrane of the type available from Spectral Diagnostics, Inc., Toronto, Canada. Optional reflector 18 A may be on, or adjacent to, a surface of layer 26 and positioned over measurement area 18 . If the reflector is present, the device becomes a transflectance device. [0064] The method of using the strip of FIGS. 1, 2, and 3 can be understood with reference to a schematic of the elements of a meter shown in FIG. 4, which contemplates an automated meter. Alternatively, manual operation is also possible. (In that case, bladder 14 is manually depressed before sample is applied to sample port 12 , then released.) The first step the user performs is to turn on the meter, thereby energizing strip detector 40 , sample detector 42 , measurement system 44 , and optional heater 46 . The second step is to insert the strip. Preferably, the strip is not transparent over at least a part of its area, so that an inserted strip will block the illumination by LED 40 a of detector 40 b . (More preferably, the intermediate layer is formed of a non-transparent material, so that background light does not enter measurement system 44 .) Detector 40 b thereby senses that a strip has been inserted and triggers bladder actuator 48 to compress bladder 14 . A meter display 50 then directs the user to apply a sample to sample port 12 as the third and last step the user must perform to initiate the measurement sequence. The empty sample port is reflective. When a sample is introduced into the sample port, it absorbs light from LED 42 a and thereby reduces the light that is reflected to detector 42 b . That reduction in light, in turn, signals actuator 48 to release bladder 14 . The resultant suction in channel 16 draws sample through measurement area 18 to stop junction 22 . Light from LED 44 a passes through measurement area 18 , and detector 44 b monitors the light transmitted through the sample as it is clotting. When there are multiple measurement areas, measurement system 44 includes an LED/detector pair (like 44 a and 44 b ) for each measurement area. Analysis of the transmitted light as a function of time (as described below) permits a calculation of the PT time, which is displayed on the meter display 50 . Preferably, sample temperature is maintained at about 37° C. by heater 46 . [0065] As described above, the detector senses a sample in sample port 12 , simply by detecting a reduction in (specular) reflection of a light signal that is emitted by 42 a and detected by 42 b . However, that simple system cannot easily distinguish between a whole blood sample and some other liquid (e.g., blood serum) placed in the sample port in-error or, even, an object (e.g., a finger) that can approach sample port 12 and cause the system to erroneously conclude that a proper sample has been applied. To avoid this type of error, another embodiment measures diffuse reflection from the sample port. This embodiment appears in FIG. 4A, which shows detector 42 b positioned normal to the plane of strip 10 . With the arrangement shown in FIG. 4A, if a whole blood sample has been applied to sample port 12 , the signal detected by 42 b increases abruptly, because of scattering in the blood sample, then decreases, because of rouleaux formation (discussed below). The detector system 42 is thus programmed to require that type of signal before causing actuator 48 to release bladder 14 . The delay of several seconds in releasing bladder 14 does not substantially affect the readings described below [0066] [0066]FIG. 5 depicts a typical “clot signature” curve in which the current from detector 44 b is plotted as a function of time. Blood is first detected in the measurement area by 44 b at time 1 . In the time interval A, between points 1 and 2 , the blood fills the measurement area. The reduction in current during that time interval is due to light scattered by red cells and is thus an approximate measure of the hematocrit. At point 2 , sample has filled the measurement area and is at rest, its movement having been stopped by the stop junction. The red cells begin to stack up like coins (rouleaux formation). The rouleaux effect allows increasing light transmission through the sample (and less scattering) in the time interval between points 2 and 3 . At point 3 , clot formation ends rouleaux formation and transmission through the sample reaches a maximum. The PT time can be calculated from the interval B between points 1 and 3 or between 2 and 3 . Thereafter, blood changes state from liquid to a semi-solid gel, with a corresponding reduction in light transmission. The reduction in current C between the maximum 3 and endpoint 4 correlates with fibrinogen in the sample. [0067] The device pictured in FIG. 2 and described above is preferably formed by laminating thermoplastic sheets 26 and 28 to a thermoplastic intermediate layer 24 that has adhesive on both of its surfaces. The cutouts that form the elements shown in FIG. 1 may be formed, for example, by laser- or die-cutting of layers 24 , 26 , and 28 . Alternatively, the device can be formed of molded plastic. Preferably, the surface of sheet 28 is hydrophilic. (Film 9962, available from 3M, St. Paul. Minn.) However, the surfaces do not need to be hydrophilic, because the sample fluid will fill the device without capillary forces. Thus, sheets 26 and 28 may be untreated polyester or other thermoplastic sheet, well known in the art. Similarly, since gravity is not involved in filling, the device can be used in any orientation. Unlike capillary fill devices that have vent holes through which sample could leak, the present device vents through the sample port before sample is applied, which means that the part of the strip that is first inserted into the meter is without an opening, reducing the risk of contamination. [0068] [0068]FIG. 6 is a plan view of another embodiment of the device of the present invention, in which the device to includes a bypass channel 52 that connects channel 16 with bladder 14 . The function and operation of the bypass channel can be understood by referring to FIGS. 6A, 6B, and 6 C which depict a time sequence during which a sample is drawn into device 10 for the measurement. [0069] [0069]FIG. 6A depicts the situation after a user has applied a sample to the strip, while bladder 14 is compressed. This can be accomplished by applying one or more drops of blood. [0070] [0070]FIG. 6B depicts the situation after the bladder is decompressed. The resulting reduced pressure in the inlet channel 16 draws the sample initially into the measurement area 18 . When the sample reaches stop junction 22 , the sample encounters a back pressure that causes it to stop and causes additional sample to be drawn into the bypass channel. [0071] [0071]FIG. 6C depicts the situation when a reading is taken. Sample is isolated and at rest in measurement area 18 . Excess sample and/or air has been drawn into bypass channel 52 . [0072] The bypass channel of FIG. 6 provides an important improvement over the operation of the “basic” strip-of FIGS. 1 - 3 . In the basic strip, stop junction 22 stops the flow of sample after it fills measurement area 18 . As was discussed earlier, it is important to stop the flow in order to facilitate rouleaux formation. As was also discussed earlier, the stop junction accomplishes the flow stoppage as a result of surface tension acting on the meniscus at the leading edge of the fluid at an abrupt change in cross section of the flow channel. In the basic strip, the pressure on the bladder side of the stop junction remains below atmospheric pressure while the pressure on the sample side remains open to atmosphere. Thus, there is an ambient pressure imbalance on the two sides. The greater the imbalance, the greater the risk that the stop junction will leak and that sample will flow through the stop junction, interfering with rouleaux formation, and, consequently, providing inaccurate values of PT. [0073] Bypass channel 52 minimizes that risk. The reduced pressure on the bladder side of the stop junction draws sample into the bypass channel (FIGS. 6B, 6C) until the ambient pressure is equalized at atmospheric pressure on both sides of the stop junction. Note that the (reduced) pressure on the bladder side is relatively uncontrolled. The bypass channel 52 , by enabling the pressures on the two sides of the stop junction to equilibrate, permits the use of larger bladders that have greater suction. Larger bladders, in turn, provide more reliable operation of the system. [0074] [0074]FIG. 7 depicts an embodiment of the present invention in which there are multiple (three are shown) measurement areas “in parallel”. That is to say that the channels 116 P, 216 P, and 316 P fill substantially simultaneously (assuming they have the same dimensions). The situation depicted in FIG. 7, with channels and measurement areas filled with blood, is achieved, as discussed above, by applying sample to sample pott 112 while bladder 114 is compressed, then releasing bladder 114 . As discussed above, the first step is to apply sample to sample well 112 while bladder 114 is compressed. The second step is to release the bladder. Sample flows to measurement areas 118 P, 218 P, and 318 P, and flow stops when sample reaches stop junctions, 122 P, 222 P, and 322 P, respectively. The optional second and third measurement areas may contain, for example, reagents that neutralize the presence of interferents (such as heparin) in the blood, or that provide a built-in control on the PT measurement, or that measure another blood parameter (such as APPT) [0075] [0075]FIG. 8 is a schematic illustration of an embodiment in which multiple measurement areas are “in series”, meaning that they fill sequentially. In this embodiment, measurement areas 118 S, 218 S, and 318 S fill sequentially, through a single channel 116 S, until the sample reaches stop junction 122 S. A potential drawback of this design is that sample passing from one measurement area to the next may carry over reagent. [0076] [0076]FIG. 9 is a schematic of another embodiment of a device that is adapted for multiple sequential tests. In that embodiment stop junctions 122 T, 222 T, and 322 T permit a user to control the timing of sequential filling of measurement areas 118 T, 218 T, and 318 T. In operation, bladders 114 , 214 , and 314 are all compressed before a blood sample is applied to sample well 112 . Bladder 114 is then released to draw blood into measurement area 118 T to stop junction 122 T. At a selected later time, bladder 214 is released to permit blood to break through stop junction 122 T and enter measurement area 218 T to stop junction 222 T. Finally, when the user wishes to use measurement area 318 T, bladder 314 is decompressed, permitting sample to break through stop function 222 T and flow to stop junction 322 T. The device of FIG. 9 must be carefully formed, since the force drawing sample into the device—caused by decompressing a bladder—must be balanced against the opposing force—exerted by a stop junction. If the drawing force is too great, a stop junction may prematurely permit sample to pass; if it's too small, it will not draw the sample through a stop junction, when that is intended. [0077] [0077]FIG. 10 depicts a preferred embodiment of the present device. It is a parallel multi-channel device that includes bypass channel 152 P. Bypass channel 152 P serves a purpose in this device that is analogous to that served by bypass channel 52 in the device of FIG. 6, which was described above. Measurement area 118 P contains thromboplastin. Preferably, measurement areas 218 P and 318 P contain controls, more preferably, the controls described below. Area 218 P contains thromboplastin, bovine eluate, and recombinant Factor VIIa. The composition is selected to normalize the clotting time of a blood sample by counteracting the effect of an anticoagulant, such as warfarin. Measurement area 318 P contains thromboplastin and bovine eluate alone, to partially overcome the effect of an anticoagulent. Thus, 3 measurements are made on the strip. PT time of the sample, the measurement of primary interest, is measured on area 118 P. However, that measurement is validated only when measurements on areas 218 P and 318 P yield results within a predetermined range. If either or both of these control measurements are outside the range, then a retest is indicated. Extended stop junction 422 stops flow in all three measurement areas. [0078] [0078]FIG. 11 depicts a device that includes bypass channels 152 S and 252 S to permit timed filling of measurement areas 118 T and 218 T. Operation of the device of FIG. 11 is analogous to that of the device of FIG. 9, described above, with the following exception. First bypass channel 152 S has a region in which a reagent that causes clotting, such as thromboplastin, is coated. As a first measurement is made in reagent area 118 T, a clot forms in blood that had been drawn into bypass channel 152 S. Thus, when the second bladder is decompressed, blood is blocked from being drawn through bypass 152 S and instead is drawn though stop junction 122 T to measurement area 218 T and bypass channel 252 S. [0079] All the previous figures depict the device of this invention as a laminated strip structure; however, the device could also be an injection-molded structure of the type shown in FIGS. 12 and 13. FIG. 12 is an exploded view of an injection-molded device 110 , including top layer 126 and bottom layer 128 sandwiching intermediate layer 124 . The intermediate layer has depressions in its top surface that form sample port 112 , channel 116 , measurement area 118 , and optional bypass channel 152 . Stop junction 122 passes through the thickness of intermediate layer 124 . Sample flow stops at the interface between stop junction 122 and channel A, which is formed by a depression in the bottom surface. Thus, the sample flows from sample port 112 through channel 116 to measurement area 118 into stop junction 122 . [0080] The principle of operation of the injection molded device is the same as described above. It provides greater flexibility in the design of the stop junction, as well as the other elements of the device, because a wide range of channel cross sections are feasible. The molded structure also provides more rigidity, although it is substantially more costly. [0081] The following examples demonstrate the present invention in its various embodiments, but are not intended to be in any way limiting. EXAMPLE 1 [0082] A strip of this invention is made by first passing a double-sided adhesive tape (RX 675SLT, available from Scapa Tapes, Windsor, Conn.) sandwiched between two release liners into a laminating and rotary die-cutting converting system. The pattern shown in FIG. 6, with the exception of the stop junction, is cut through the top release liner and tape, but not through the bottom release liner, which is then removed as waste, along with the cutouts from the tape. Polyester film treated to be hydrophilic (3M9962, available from 3M, St. Paul, Minn.) is laminated to the exposed bottom side of the tape. Reagent (thromboplastin, available from Ortho Clinical Diagnostics, Raritan, N.J.) is then printed onto the reagent area ( 18 ) of the polyester film by bubble jet printing, using printing heads 51612A, from Hewlett Packard, Corvallis, Oreg. A sample port is cut in untreated polyester film (AR1235, available from Adhesives Research, Glen Rock, Pa.) and then laminated, in register, to the top of the double-sided tape (after removing the release layer). A die then cuts the stop junction through the three layers of the sandwich. Finally, strips of single-sided adhesive tape (MSX4841, available from 3M, St. Paul, Minn.) are applied to the outside of the polyester layers to seal the stop junction. EXAMPLE 2 [0083] A procedure that is similar to the one described in Example 1 is followed to make a strip of the type depicted in FIG. 10. Reagent that is bubble-jet printed onto areas 118 P, 218 P, and 318 P is, respectively, thromboplastin; thromboplastin, bovine eluate, and recombinant Factor VIIa; and thromboplastin and bovine eluate alone. The bovine eluate (plasma barium citrate bovine eluate) is available from Haembtologic Technologies, Burlington, Vt.; and recombinant Factor VIIa from American Diagnostica, Greenwich, Conn. [0084] Measurements made on a whole blood sample using the strip of this Example yield a curve of the type shown in FIG. 5 for each of the measurement areas. The data from the curves for the controls (measurement areas 218 P and 318 P) are used to qualify the data from the curve for measurement area 118 P. As a result, the PT time can be determined more reliably than can be done with a strip having a single measurement area. EXAMPLE 3 [0085] The device of FIGS. 12 and 13 is formed by sandwiching middle layer 124 between top layer 126 and bottom layer 128 . The middle and bottom layers are injection molded polycarbonate (Lexan*121) and have thicknesses of 6.3 mm and 1.5 mm, respectively. Top layer 126 is made by die cutting 0.18 mm Lexan* 8010 sheet. The elements are ultrasonically welded after the reagent of Example 1 is applied to reagent area 118 . The Lexan* material is available from General Electric, Pittsfield, Mass. [0086] The invention having been fully described, it will be apparent to one of ordinary skill in the art that many modifications and changes may be made to it without departing from the spirit and scope of the present invention.

A fluidic medical diagnostic device permits measurement of analyte concentration or a property of a biological fluid, particularly the coagulation time of blood. The device has at one-end a sample port for introducing a sample and at the other end a bladder for drawing the sample to a measurement area. A channel carries the sample from the sample port to the measurement area, and a stop junction, between the measurement area and bladder, halts the sample flow. The desired measurement can be made by placing the device into a meter which measures a physical property of the sample—typically, optical transmittance—after it has interacted with a reagent in the measurement area.

FIELD OF THE INVENTION [0001] This invention relates to composite materials for restorative dentistry. More particularly, it relates to a dental composite material that combines reduced shrinkage with sufficiently low viscosity, high polymerization rate, and good mechanical properties. BACKGROUND OF THE INVENTION [0002] In recent years, composite materials comprising highly filled polymer have become commonly used for dental restorations. A thorough summary of current dental composite materials is provided in N. Moszner and U. Salz, Prog. Polym. Sci. 26:535-576 (2001). Currently used dental filling composites contain crosslinking acrylates or methacrylates, inorganic fillers such as glass or quartz, and a photoinitiator system, enabling them to be cured by radiation with visible light. Typical methacrylate materials include 2,2′-bis[4-(2-hydroxy-3-methacryloyloxypropyl)phenyl]propane (“Bis-GMA”); ethoxylated Bis-GMA (“EBPDMA”); 1,6-bis-[2-methacryloyloxyethoxycarbonylamino]-2,4,4-trimethylhexane (“UDMA”); dodecanediol dimethacrylate (“D 3 MA”); and triethyleneglycol dimethacrylate (“TEGDMA”). [0003] Dental composite materials offer a distinct cosmetic advantage over traditional metal amalgam. However, they do not offer the longevity of amalgam in dental fillings. The primary reasons for failure are believed to be excessive shrinkage during photopolymerization in the tooth cavity, which causes leakage and bacterial reentry, and inadequate strength and toughness. [0004] The incumbent low-shrink monomer, Bis-GMA, the condensation product of bisphenyl A and glycidyl methacrylate, is an especially important monomer in dental composites. However, it is highly viscous at room temperature and consequently insufficiently converted to polymer. It is therefore typically diluted with a less viscous acrylate or methacrylate monomer, such as trimethylol propyl trimethacrylate, 1,6-hexanediol dimethacrylate, 1,3-butanediol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, TEGDMA, or tetraethylene glycol dimethacrylate. However, while providing fluidity, low molecular weight monomers contribute to increased shrinkage. Increasingly, Bis-GMA and TEGDMA have been combined with UDMA and ethoxylated-methacrylated versions of bisphenyl A, but shrinkage remains too high. [0005] Increasing the amount of inorganic filler in the composite has moderated shrinkage. However, the amount of filler that can be added is severely limited by the resulting increase in viscosity. Also, it has been reported that the increase in modulus more than offsets this benefit and can lead to an increased build-up of stress during shrinkage. This “contraction stress” is of great importance in that it can lead to mechanical failure and debonding of the composite from the tooth, creating a gap that can permit microleakage of oral fluid and bacteria, causing a reinfection. [0006] Another approach has been to prepolymerize the monomer, reducing the ultimate degree of polymerization and attendant shrinkage. However, this reduces the amount of inorganic filler that can be added below current levels, thus decreasing the modulus and other mechanical properties. [0007] Spiro-type, “expanding” monomers, introduced in the 1970s, eliminate shrinkage, but they have never been commercialized because they polymerize too slowly and they, or their polymerization products, are too unstable. Diepoxide monomers are similarly limited in that they polymerize slowly for practical application, and the monomers and photosensitizers may be too toxic. They do not entirely eliminate shrinkage. [0008] Slow cure and the so-called “soft start” photocure are also reported to reduce contraction stress. [0009] Other systems have been reported in the literature but are not commercial. Liquid crystalline di(meth)acrylates shrink far less, but there is a tradeoff in mechanical properties. Branched polymethacrylates and so-called “macromonomers” offer lower viscosity at reduced shrinkage, but cost of manufacture may be excessive. [0010] Published, unexamined Japanese Application JP2001122721 discloses tetramethylspirobisindanediol compounds wherein the benzene ring side chains comprise linear or branched (poly)oxyalkylenes with terminal (meth)acrylates. [0011] U.S. Pat. No. 5,486,548 issued to Podszun et al. on Jan. 23, 1996, discloses di(meth)acrylate derivatives of cyclohexyldiphenyls that, when used in dental compositions, display a low degree of shrinkage upon polymerization. [0012] B. Culbertson et al., Poly. Adv. Tech. 10:275-281 (1999) describes the synthesis and use of ethoxymethacrylate and propoxymethacrylate derivatives of fluorenylbisphenyl A. [0013] U.S. Pat. No. 6,608,167 issued to Hayes et al. on Aug. 19, 2003, discloses a process for producing bis(2-hydroxyethyl)isosorbide. [0014] There remains a need for a dental composite material that combines reduced shrinkage with sufficiently low viscosity, high polymerization rate, and acceptable mechanical properties. SUMMARY OF THE INVENTION [0015] The present invention provides a dental composite material comprising at least one (meth)acrylic ester compound, at least one polymerization initiator, at least one inorganic filler, and at least one space-filling compound. The invention also provides a method of producing a dental restoration article using at least one (meth)acrylic ester compound, at least one polymerization initiator, at least one inorganic filler, and at least one space-filling compound. [0016] Further disclosed is a method of treating dental tissue with a direct composite, comprising the steps of: (a) placing a dental composite material, as desribed above, on a dental tissue; (b) curing the dental composite material; and (c) shaping the dental composite material. DETAILED DESCRIPTION OF THE INVENTION [0020] Applicants specifically incorporate the entire content of all cited references in this disclosure. Applicants also incorporate by reference the co-owned and concurrently filed applications entitled “Dental Composites Containing Core-Shell Polymers with Low Modulus Cores” (Attorney Docket # CL 2434), “Dental Compositions Containing Liquid and Other Elastomers” (Attorney Docket # CL 2368), and “Branched Highly-Functional Monomers Exhibiting Low Polymerization Shrinkage” (Attorney Docket # CL 2452). [0021] In the context of this disclosure, a number of terms shall be utilized. [0022] The terms “(meth)acrylic” and “(meth)acrylate” as used herein denote “methacrylic or acrylic” and “methacrylate or acrylate” respectively. [0023] The term “dental composite material” as used herein denotes a composition that can be used to remedy natural or induced imperfections of, and relating to, teeth. Examples include filling materials, reconstructive materials, restorative materials, crown and bridge materials, inlays, onlays, laminate veneers, dental adhesives, teeth, facings, pit and fissure sealants, cements, denture base and denture reline materials, orthodontic splint materials, and adhesives for orthodontic appliances. [0024] Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range. [0025] The (meth)acrylic ester compound used in the present invention can comprise either a monofunctional compound or a polyfunctional compound which means a compound having one (meth)acrylic group and a compound having more than one (meth)acrylic group respectively. Specific examples of monofunctional (meth)acrylic ester compounds include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hydroxyethyl (meth)acrylate, benzyl (meth)acrylate, methoxyethyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and methacryloyloxyethyltrimellitic mono ester and its anhydride. [0026] Specific examples of polyfunctional (meth)acrylic ester compounds include di(meth)acrylates of ethylene glycol derivatives as represented by the general formula wherein R is hydrogen or methyl and n is an integer in a range of from 1 to 20, such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate; 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, dodecanediol di(meth)acrylate, glycerol di(meth)acrylate, bisphenyl A di(meth)acrylate, bisphenyl A diglycidyl di(meth)acrylate and ethoxylated bisphenyl A diglycidyl di(meth)acrylate; urethane di(meth)acrylates; trimethylolpropane tri(meth)acrylate; tetrafunctional urethane tetra(meth)acrylates; pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and hexa(meth)acrylates of urethanes having an isocyanuric acid skeleton. [0027] These (meth)acrylic ester compounds may be used alone or in admixture of two or more. The mixtures can be mixtures of monofunctionals, polyfunctionals, or both. [0028] The (meth)acrylic ester compound used in the dental compositions preferably comprises at least one polyfunctional (meth)acrylic ester compound, and more preferably comprises at least two polyfunctional (meth)acrylic ester compounds. [0029] The space-filling compound of the present invention is a monomer comprising a rigid, angular, bulky moiety that can be compounded into composites, which upon polymerization exhibit low volumetric shrinkage. By “space-filling compound” is meant a monomer comprising a moiety with an inability of a significant fraction of its constituent atoms to be place in a common plane. By “significant fraction” is meant greater than about 15%. Additionally, the constituent atoms have a relative lack of mobility with respect to one another; that is, the moiety's structure is highly rigid and preferably has less than two freely rotating internal bonds. [0030] In accordance with one aspect of the invention, the space-filling compounds comprise derivatives of at least one of the moieties spirobisindanediol (“SBID”), phenylindane dicarboxylic acid (“PIDA”), t-butylisophthalic acid (“BIPA”), cyclohexyldiphenyl, fluorenylbisphenyl A, tetrahydrodicyclopentadiol, phenyl-alkyl levulinate, and isosorbide. [0031] Preferred SBID-based space-filling compounds comprise at least one of compound (i) or (ii): wherein R 1 and R 2 are independently acryloyl; methacryloyl; 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacryl ate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; R 3 and R 4 are independently H, CH 3 , alkyl, or aralkyl such that the carbon atom attached to the cyclopentane ring is aliphatic with at least one H (i.e., —CHR—); and R 5 and R 6 are independently H, CH 3 , alkyl, or aralkyl, containing one carbon less than R 3 and R 4 respectively; provided when R 3 and R 4 are CH 3 and R 5 and R 6 are H that R 1 and R 2 are independently 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate. Preferably, R 1 and R 2 are 2-(2-ethoxycarbonylamino)ethyl methacrylate, R 3 and R 4 are CH 3 , and R 5 and R 6 are H; and wherein R 7 and R 8 are independently 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 3-acryloyloxy-2,2-dimethylpropyl; 3-methacryloyloxy-2,2-dimethylpropyl; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl acrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; R 9 and R 10 are independently H, CH 3 , alkyl, or aralkyl such that the carbon atom attached to the cyclopentane ring is aliphatic with at least one H (i.e., —CHR—); and R 11 and R 12 are independently H, CH 3 , alkyl, or aralkyl, containing one carbon less than R 9 and R 10 respectively. Preferably, R 7 and R 8 are 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate, R 9 and R 10 are CH 3 , and R 11 and R 12 are H. [0032] Preferred PIDA-based space-filling compounds (iii) comprise wherein R 13 and R 14 are independently 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 3-acryloyloxy-2,2-dimethylpropyl; 3-methacryloyloxy-2,2-dimethylpropyl; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl acrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; R 15 , R 16 , and R 17 are independently H, CH 3 , alkyl, or aralkyl such that the carbon atom attached to the cyclopentane ring is aliphatic with at least one H (i.e., —CHR—); and R 18 is H, CH 3 , alkyl, or aralkyl, containing one carbon less than R 15 , R 16 , or R 17 . Preferably, R 13 and R 14 are 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate, R 15 , R 16 , and R 17 are CH 3 and R 18 is H. [0033] Preferred phenyl-alkyl levulinate-based space-filling compounds (iv) comprise wherein R 19 and R 20 are independently acryloyl; methacryloyl; 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; R 21 , R 22 , and R 23 are independently H, CH 3 , alkyl, or aralkyl. Preferably, R 19 and R 20 are 2-(2-ethoxycarbonylamino)ethyl methacrylate, R 21 is ethyl and R 22 and R 23 are H. [0034] Preferred cyclohexyldiphenyl-based space-filling compounds (v) comprise wherein R 24 and R 25 are independently acryloyl; methacryloyl; 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; and R 26 and R 27 are independently H, CH 3 , alkyl, or aralkyl; provided when R 26 and R 27 are H that R 24 and R 25 are independently 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate. Preferably, R 24 and R 25 are 2-(2-ethoxycarbonylamino)ethyl methacrylate and R 26 and R 27 are H. [0035] Preferred fluorenylbisphenyl A-based space-filling compounds (vi) comprise wherein R 28 and R 29 are independently acryloyl; methacryloyl; 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; and R 30 and R 31 are independently H, CH 3 , alkyl, or aralkyl; provided when R 30 and R 31 are H or CH 3 that R 28 and R 29 are independently 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate. Preferably, R 28 and R 29 are 2-(2-ethoxycarbonylamino)ethyl methacrylate and R 30 and R 31 are H. [0036] Preferred tetrahydrodicyclopentadiol-based space-filling compounds (vii) comprise wherein R 32 and R 33 are independently 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacryl ate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate. Preferably, R 32 and R 33 are 2-(2-ethoxycarbonylamino)ethyl methacrylate. [0037] Preferred isosorbide-based space-filling compounds (viii) comprise wherein R 34 and R 35 are independently 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate. Preferably, R 34 and R 35 are 2-(2-ethoxycarbonylamino)ethyl methacrylate. [0038] Preferred BIPA-based space-filling compounds (ix) comprise wherein R 36 and R 37 are independently 2-acryloyloxyethyl; 2-methacryloyloxyethyl; 2-acryloyloxypropyl; 2-methacryloyloxypropyl; 3-acryloyloxy-2,2-dimethylpropyl; 3-methacryloyloxy-2,2-dimethylpropyl; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl acrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; or 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate. Preferably, R 36 and R 37 are 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate. [0039] Monomers of diol-based space-filling compounds can be reacted with ethylene or propylene oxide, for example, to produce low molecular weight alkoxylate oligomers that can then be (meth)acrylated to produce free radical-polymerizable monomers. Monomers of dicarboxylic acid-based space-filling compounds can be esterfied with diols, for example, to produce low molecular weight esterdiol oligomers that can then be (meth)acrylated to produce free radical-polymerizable monomers. [0040] In another aspect of the invention, dental composite materials comprise a space-filling compound that has been functionally terminated with at least two urethane (meth)acrylate groups. Preferably, the space-filling compound is functionally terminated with 2-(carbonylamino)ethyl acrylate; 2-(carbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl acrylate; 2-[2-(2-ethoxy)ethoxycarbonylamino]ethyl methacrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxyethylenecarbonylamino)ethyl methacrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl acrylate; 2-(omega-polyoxypropylenecarbonylamino)ethyl methacrylate; 2-(2-ethoxycarbonylamino)ethyl acrylate; 2-(2-ethoxycarbonylamino)ethyl methacrylate; 2-[1-(2-propoxy)carbonylamino]ethyl acrylate; 2-[1-(2-propoxy)carbonylamino]ethyl methacrylate; 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl acrylate; or 2-[3-(2,2-dimethylpropoxy)carbonylamino]ethyl methacrylate. [0041] In dental composite materials, space-filling compounds of the present invention can be used in the range of about 1 weight percent to 100 weight percent, preferably in the range of about 20 weight percent to about 80 weight percent, and more preferably in the range of about 40 weight percent to about 60 weight percent, the percentages being based on the total weight exclusive of filler. [0042] The production of the crosslinked polymers useful in the practice of this invention from monomers and crosslinking agents may be performed by any of the many processes known to those skilled in the art. Thus, the polymers may be formed by heating a mixture of the components to a temperature sufficient to cause polymerization. For this purpose, peroxy-type initiators such as benzoyl peroxide, dicumyl peroxide, lauryl peroxide, tributyl hydroperoxide, and other materials familiar to those skilled in the art may be employed, and the use of activators may be advantageous in some formulations. Suitable activators include, for example, N,N-bis-(hydroxyalkyl)-3,5-xylidines, N,N-bis-(hydroxyalkyl)-3,5-di-t-butylanilines, barbituric acids and their derivatives, and malonyl sulfamides, including specific examples of these activators found in published U.S. Patent Application 2003/0008967. Azo-type initiators such as 2,2′-azobis(isobutyronitrile), 2,2′-azobis(2,4-dimethyl valeronitrile), 2,2′-azobis(2-methyl butane nitrile), and 4,4′-azobis(4-cyanovaleric acid) may also be used. Alternatively, the crosslinked polymers of the invention may be formed from the constituents by photochemical or radiant initiation utilizing light or high energy radiation. For photochemical initiation, photochemical sensitizers, or energy transfer compounds may be employed to enhance the overall polymerization efficiency in manners well known to those skilled in the art. [0043] Suitable photoinitiators include, for example, camphor quinone, benzoin ethers, α-hydroxyalkylphenones, acylphosphine oxides, α,α-dialoxyacetophenones, α-aminoalkylphenones, acyl phosphine sulfides, bis acyl phosphine oxides, phenylglyoxylates, benzophenones, thioxanthones, metallocenes, bisimidazoles, and α-diketones. [0044] Photoinitiating accelerators may also be present. Such photoinitiating accelerators include, for example, ethyl dimethylaminobenzoate, dimethylaminoethyl methacrylate, dimethyl-p-toluidine, and dihydroxyethyl-p-toluidine. [0045] According to another aspect, an inorganic filler is included in the composite. Included in the inorganic fillers are the preferred silicious fillers. More preferred are the inorganic glasses. Among these preferred inorganic fillers are barium aluminum silicate, lithium aluminum silicate, strontium fluoride, lanthanum oxide, zirconium oxide, bismuth phosphate, calcium tungstate, barium tungstate, bismuth oxide, tantalum aluminosilicate glasses, and related materials. Glass beads, silica, especially in submicron sizes, quartz, borosilicates, alumina, alumina silicates, and other fillers may also be employed. For example, Aerosil® OX-50 fumed silica from Degussa can be used. Mixtures of fillers may also be employed. The average diameter of the inorganic fillers is preferably less than 15 μm, even more preferably less than 10 μm. [0046] Such fillers may be silanated prior to use in this invention. Silanation is well known to those skilled in the art and any silanating compound known to them may be used for this purpose. By “silanation” is meant that some of the silanol groups have been substituted or reacted with, for example, dimethyldichlorosilane to form a hydrophobic filler. The particles are typically from 50 to 95 percent silanated. Silanating agents for inorganic fillers include, for example, γ-mercaptoproyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-methacryloyloxypropyltriethoxysilane. [0047] The (meth)acrylic ester compound can be used in the range of about 1 weight percent to about 99 weight percent, preferably in the range of about 20 weight percent to about 80 weight percent, and more preferably in the range of about 40 weight percent to about 60 weight percent, the percentages being based on the total weight exclusive of filler. [0048] The polymerization initiator with, optionally, a photoinitiating accelerator can be used in the range of about 0.1 weight percent to about 5 weight percent, preferably in the range of about 0.2 weight percent to about 3 weight percent, and more preferably in the range of about 0.2 weight percent to about 2 weight percent, the percentages being based on the total weight exclusive of filler. [0049] The inorganic filler can be used in the range of about 20 weight percent to about 90 weight percent, preferably in the range of about 40 weight percent to about 90 weight percent, and more preferably in the range of about 50 weight percent to about 85 weight percent, the percentages being based on the total weight of the (meth)acrylic ester compound, the polymerization initiator, the inorganic filler, and the space-filling compound. [0050] In addition to the components described above, the blend may contain additional, optional ingredients. These may comprise activators, pigments, radiopaquing agents, stabilizers, antioxidants, and other materials as will occur to those skilled in the art. [0051] Suitable pigments include, for example, inorganic oxides such as titanium dioxide, micronized titanium dioxide, and iron oxides; carbon black; azo pigments; phthalocyanine pigments; quinacridone pigments; and pyrrolopyrrol pigments. [0052] Preferred radiopaquing agents include, for example, ytterbium trifluoride, yttrium trifluoride, barium sulfate, bismuth subcarbonate, bismuth trioxide, bismuth oxichloride, and tungsten. [0053] Preferred stabilizers can include, for example, hydroquinone, hydroquinone monomethyl ether, 4-tert-butylcatechol, and 2,6-di-tert-butyl-4-methylphenyl. [0054] Primary antioxidants, secondary antioxidants, and thioester-type antioxidants are all suitable for use in the dental compositions of the invention. Preferred primary antioxidants comprise hindered phenyl and amine derivatives such as butylated hydroxytoluene, butylated hydroxyanisole, t-butyl hydroquinone, and α-tocopherol. Preferred secondary antioxidants include phosphites and phosphonites such as tris(nonylphenyl) phosphite, tris(2,4-di-t-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, bis(2,4-dicumylphenyl) pentaerythritol diphosphite, and Irgafos® P-EPQ (Ciba Specialty Chemicals, Tarrytown, N.Y.). Preferred thioester-type antioxidants, used synergistically or additively with primary antioxidants, include dilauryl 3,3′-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, and ditridecyl 3,3′-thiodipropionate. [0055] Organic fillers, comprising prepolymerized material, optionally comprising at least one of the (meth)acrylic ester compounds and space-filling compounds, and optionally comprising inorganic filler, may also be included in the composite material. Prepolymerization filler can be produced by any method known in the art, for example, by the method described in published U.S. patent application 2003/0032693. Optionally, uniformly-sized bead methacrylate polymers, such as Plexidon® or Plex® available from Röhm America LLC (Piscataway, N.J.), may be utilized as organic fillers. [0056] The dental composite materials of the present invention can be used in any treatment method known to one of ordinary skill in the art. Treatment in this context includes preventative, restorative, or cosmetic procedures using the dental composites of the present invention. Typically, without limiting the method to a specific order of steps, the dental composite materials are placed on a dental tissue, either natural or synthetic, the dental composite materials are cured by any method known to one of ordinary skill in the art, and the dental composite materials are shaped as necessary to conform with the target dental tissue. Dental tissue includes, but is not limited to, enamel, dentin, cementum, pulp, bone, and gingiva. [0057] The dental composite materials of the present invention are suitable for a very wide range of dental uses, including fillings, teeth, bridges, crowns, inlays, onlays, laminate veneers, facings, pit and fissure sealants, cements, denture base and denture reline materials, orthodontic splint materials, and adhesives for orthodontic appliances. The materials of the invention may also be utilized for prosthetic replacement or repair of various hard body structures such as bone and may be utilized for reconstructive purposes during surgery, especially oral surgery. They are also useful for various non-dental uses as, for example, in plastic construction materials. EXAMPLES [0058] The present invention is further defined in the following Examples. It should be understood that these Examples, while indicating preferred embodiments of the invention, are given by way of illustration only. From the above discussion and these Examples, one skilled in the art can ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various uses and conditions. [0059] The meaning of abbreviations is as follows: “hr.” means hour(s), “min.” means minute(s), “sec.” means second(s), “ml” means milliliter(s), “cm” means centimeter(s), “mm” means millimeter(s), “g” means gram(s), “mmol” means millimole(s), “wt %” means weight percent(age), “mW” means milliwatt(s), “atm.” means atmosphere(s), “M n ” means number average molecular weight, “MPa” means megapascal(s), “d50” means 50% of particles have a diameter below a given size, “MEHQ” means 4-methoxyphenyl, “PTFE” means polytetrafluoroethylene, “TH F” means tetrahydrofuran. Example 1 Bis-GMA/TEGDMA Glass Composition [0060] A masterbatch containing 15.0 g Bis-GMA (Sigma-Aldrich, St. Louis, Mo.), 15.0 g TEGDMA (Sigma-Aldrich), 0.40 g camphor quinone (Sigma-Aldrich), and 0.40 g ethyl 4-N,N-dimethylaminobenzoate (Sigma-Aldrich) was made up by mixing the components well under subdued light. Then, 5.0 g of this masterbatch was combined and mixed well with 1.0 g untreated Degussa OX-50 fumed silica followed by 14.0 g Schott 8235 UF1.5 (d50=1.5 micron) glass powder coated with 2.3 wt % trimethoxysilylpropyl methacrylate. The blend was then placed on a PTFE sheet and mixed by folding over and flattening out the doughy composition 60 times. The resin-glass mixture was degassed under 40 mm Hg vacuum for 18 hr. at room temperature followed by heating in a vacuum oven at 45° C. with very slight vacuum for an additional 16 hr. This composition contained 25.0 wt % resin, 5.0 wt % fumed silica, and 70.0 wt % glass. Example 2 Synthesis of Tetramethylspirobisindanediol (“SBID”) [0061] A mixture of 500 g bisphenyl A and 1000 ml 48% aqueous hydrobromic acid was stirred at reflux under nitrogen overnight (about 16 hrs.) in a 2 l 3-neck flask with overhead stirrer and reflux condenser. The mixture was cooled to room temperature, and the upper red phase, which contained the product, solidified. The hydrobromic acid was decanted off, and the solid product was crushed and washed on a fritted filter funnel with water until the washes were neutral to pH paper. [0062] The product was taken up in 500 ml boiling methanol and precipitated by addition of 700 ml water to the boiling solution. Suction filtration of the thick slurry yielded a tan powder that was taken up in 600 ml boiling methanol. Addition of 100 ml water just started to cause precipitation, so 10-20 ml methanol was added to form a clear solution, and then the mixture was cooled in ice. The solids were suction filtered and taken up in 400 ml boiling methanol. This solution was cooled in ice, the resulting slurry was suction filtered, and the solids were washed with 2×100 ml methanol. Air-drying on the funnel yielded 67 g tetramethylspirobisindanediol (“SBID”). The filtrate was evaporated down to about half its volume and chilled in ice. Suction filtration yielded 72 g less pure SBID. [0063] The resulting compound has the formula: [0064] Lower case letters refer to 1 H NMR (CDCl 3 ; sparingly soluble) results as follows: 1.31 ppm (s, a, 3H); 1.36 (s, a′, 3H); 2.22 (d, J=13.1 Hz, b, 1H); 2.32 (d, J=13.1 Hz, b, 1H); 4.38 (s, C, 1H); 6.20 (d, J=2.3 Hz, d, 1H); 6.68/6.71 (d of d, J=2.4, 8.2 Hz, e, 1H); 7.02 (d, J=8.2 Hz, f, 1H). Example 3 Synthesis of Tetramethylspirobisindane Bis(2-Hydroxyethyl Ether) (“SBID EO”) [0065] A 5.0 g sample (16 mmol; 32 mmol OH) of SBID from Example 2 was dissolved in 50 ml MeOH. The hazy solution was clarified through a 5-micron syringe filter and combined with 0.5 g (4.5 mmol) potassium t-butoxide in a 100 ml RB flask. A dry ice condenser and gas inlet were attached to the flask containing the pink solution, and 6.5 g (150 mmol) ethylene oxide (“EO”) was condensed into the flask. The solution became warm upon introduction of the EO. The solution was stirred at reflux under nitrogen in a 70° C. water bath for 4 hr. The solution was allowed to stand at room temperature overnight and was then rotovapped to give a white-pink solid. The powdery solid was suspended in 50 ml water, acidified with aqueous HCl, and stirred for 30 min. The suspension was suction filtered, water washed to neutral pH, and air dried under suction to yield 6.05 g off-white powder tetramethylspirobisindane bis(2-hydroxyethyl ether) (“SBID EO”). [0066] The resulting compound has the formula: [0067] Lower case letters refer to 1 H NMR (CDCl 3 ) results as follows: 1.32 ppm (s, a, 3H); 1.38 (s, a′, 3H); 2.02 (t, J=6.4 Hz, b, 1H); 2.24 (d, J=13.1 Hz, c, 1H); 2.34 (d, J=13.1 Hz, c′, 1H); 3.86 (q, J=4.9 Hz, d, 2H); 3.97 (t, J=4.6 Hz, e, 2H); 6.34 (d, J=2.4 Hz, f, 1H); 6.79/6.80 (d of d, J=2.6, 8.2 Hz, g, 1H); 7.07 (d, J=8.2 Hz, h, 1H). [0068] There were also several small triplets due to impurities at 2.11, 2.17, 3.61, 3.78, and 4.02 ppm as well as a quartet at 3.69. The impurities are due to multiple EO additions. Example 4 Synthesis of Tetramethylspirobisindane Bis[2-(2-Ethoxycarbonylamino)ethyl Methacrylate] (“SBID EOUMA”) [0069] A mixture of 3.0 g (15 mmol OH) SBID EO from Example 3, 1 drop of dibutyltin diacetate, 10 mg MEHQ, and 2.7 g (17 mmol) 2-isocyanatoethyl methacrylate in 20 ml THF in a 200 ml RB flask was stirred in a 60° C. oil bath for 1 hr. [0070] The light tan solution was quickly rotovapped to remove over half of the solvent, and the liquid concentrate was stirred with 100 ml hexane for 1 hr. The hexane was decanted from the taffy-like product, and 100 ml fresh hexane was added. The mixture was stirred for 1 hr., and the hexane was decanted off. A solution of 10 mg MEHQ in 2 ml dichloromethane was added and mixed well. The solution was held under vacuum with an air bleed to remove solvent, yielding 5.68 g tetramethylspirobisindane bis[2-(2-ethoxycarbonylamino)ethyl methacrylate] (“SBID EOUMA”). NMR indicated complete conversion of the SBID EO hydroxyls to urethane methacrylate groups, the OH peak at 2.02 ppm having been replaced by the methacrylate methyl at 1.92 ppm. [0071] The resulting compound has the formula: [0072] Lower case letters refer to 1 H NMR (CDCl 3 ) results as follows: 1.31 ppm (s, a, 3H); 1.37 (s, a′, 3H); 1.92 (s, b, 3H); 2.23 (d, J=13.1 Hz, c, 1H); 2.33 (d, J=13.1 Hz, c′, 1H); 3.48 (br m, d, 2H); 4.04 (t, e, 2H); 4.20 (t, f, 2H); 4.35 (t, g, 2H); 5.09 (t, h, <1H); 5.56 (s, i, 1H); 6.09 (s, j, 1H); 6.32 (d, J=2.2 Hz, k, 1H); 6.77/6.79 (d of d, J=2.6, 8.2 Hz, l, 1H); 7.07 (d, J=8.2 Hz, m, 1H). Example 5 SBID EOUMA/TEGDMA—Glass Composition [0073] A TEGDMA/photoinitiator masterbatch was produced by combining 10.0 g TEGDMA with a solution of 0.20 g phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Sigma-Aldrich) in 0.5 ml dichloromethane. The flask was covered with foil, and the solution magnetically stirred under 10-20 mm Hg vacuum for 1 hr. with an air bleed to carry off solvent. [0074] A mixture of 1.25 g TEGDMA/photoinitiator masterbatch and 1.25 g SBID EOUMA from Example 4 was combined in a scintillation vial and mixed with a spatula to a uniform mixture. Then, 0.50 g Degussa OX-50 fumed silica was mixed in with a spatula, followed by 7.0 g silanated Schott 8235 UF1.5 glass powder. The blend was placed on a PTFE sheet and mixed by folding over and flattening out the doughy composition 40 times. The glass-resin blend was held under 40 mm Hg vacuum at room temperature for 16 hrs. and then in an oven at 45° C. under 1 atm. air for 24 hrs. This composition contained 25.0 wt % resin, 5.0 wt % fumed silica, and 70.0 wt % glass. The resin-glass blend was molded and cured into bars for physical testing as described below in Example 6. Example 6 [0075] Fracture toughness (K IC ), flexural strength (ISO 4049), and density were determined on molded and cured bars of the resin composition (Bis-GMA/TEGDMA from Example 1 and SBID EOUMA/TEGDMA from Example 5). Bars (2 mm×2 mm×25 mm) were molded and cured by irradiating 2 min. on a side using an array of three Denstply Spectrum 800 dental lamps at 800 mW/cm 2 . The metal mold was covered on both sides with a 3-mil polyester film to exclude oxygen, which would inhibit cure. [0076] The fracture toughness test was based on both the ASTM polymers standard (ASTM D5045) and the ASTM ceramics standard (ASTM C1421, precracked beam method). Testing was conducted at a test speed of 0.5 mm/min. at room temperature and ambient humidity using a three-point bend fixture (span to depth ratio of 10). The specimens were molded using the flex bar mold specified in ISO 4049. The specimens were precracked halfway through the depth. Two modifications to the test procedures were made. The first was the use of smaller test specimens than those recommended in the ASTM C1421 standard (2 mm×2 mm×25 mm instead of the recommended minimum dimensions of 3 mm×4 mm×20 mm). The second was the use of a slitting circular knife to machine the precracks. The knife was 0.31 mm in thickness with a 9 degree single bevel. Tests have shown that this technique produced precracks that were equivalent to precracks produced using techniques recommended in ASTM D5045. [0077] Density determination was accomplished via helium pycnometry. The densities of the uncured glass-resin blends were determined as well. [0078] Polymerization shrinkage was determined by the equation: [(ρ cured −ρ uncured )/(ρ cured )]×100%=% S. [0079] As seen in Table 1, use of the bulky monomer with the spirobisindane structure reduced polymerization shrinkage by over 25% relative to the bisphenyl A monomer control composition without significantly reducing mechanical properties. TABLE 1 Resin Mixture SBID EOUMA/ (1:1) Bis-GMA/TEGDMA TEGDMA Shrinkage, % 4.56 3.37 K IC , MPa · m 1/2 1.88 1.69 Flex Strength, 118 129 MPa · m 1/2 Example 7 Synthesis of Tetramethylspirobisindane Bis(2-Hydroxypropyl Ether) (“SBID PO”) [0080] A 5.0 g sample (32.5 mmol OH) of SBID from Example 2 was combined with 0.1 g 2-methylimidazole and 3.5 ml (4.2 g; 41 mmol) propylene carbonate in a 100 ml RB flask under nitrogen. The dark, fluid homogeneous melt was magnetically stirred in a 180° C. oil bath for 5 hrs., and then 75 ml water was added slowly down the condenser. This mixture was stirred at reflux for 15 mins., the flask was then cooled, and the water decanted off. The solid product was broken up, and 75 ml fresh water was added. The mixture was stirred at reflux for another 15 min. The suspension was cooled and suction filtered dry to yield 6.76 g tetramethylspirobisindane bis(2-hydroxypropyl ether) (“SBID PO”). NMR indicated clean conversion to PPO diadduct. [0081] The resulting compound has the formula: [0082] Lower case letters refer to 1 H NMR (CDCl 3 ) results as follows: 1.21/1.23 ppm (s, a, 6H); 1.32/1.38 (s, b, 12H); 1.63/2.31 (br s, J=268 Hz, c, 2H); 2.24 (d, J=13.1 Hz, d, 2H); 2.34 (d, J=13.1 Hz, d, 2H); 3.68 (m, e, 2H); 3.83 (d of d, f, 2H); 4.11 (m, g, >1.5H); 4.36 (m, g, <0.5H; may be opposite addition of propylene carbonate); 6.33 (d, J=2.4 Hz, h, 2H); 6.79/6.80 (d of d, J=2.6, 8.2 Hz, i, 1H); 7.08 (d, J=8.2 Hz, h, 2H). Example 8 Synthesis of Bisphenyl A Bis(2-Hydroxypropyl Ether) (“BPA PO”) [0083] A 6.0 g sample (52.6 mmol OH) of bisphenyl A was combined with 0.1 g 2-methylimidazole and 6.0 ml (7.1 g; 70 mmol) propylene carbonate in a 100 ml RB flask under nitrogen. The homogeneous melt was magnetically stirred in a 180° C. oil bath for 5 hrs., and then 75 ml water as added slowly down the condenser. This mixture was stirred at reflux or 15 mins., the flask cooled, and the water decanted off and replaced by 75 ml fresh water. The fluid product was stirred at reflux for another 15 min. and cooled, and the water was decanted off again. The product was held under high vacuum in a boiling water bath for 2 hrs. to yield 8.92 g bisphenyl A bis(2-hydroxypropyl ether) (“BPA PO”). NMR indicated clean conversion to PPO diadduct. There also appeared to be a little PPO oligomer (1.13 ppm) present. [0084] The resulting compound has the following formula: [0085] Lower case letters refer to 1 H NMR (CDCl 3 ) results as follows: 1.25/1.27 ppm (s, a, 6H); 1.63 (s, b, 6H); 2.41 (br s, c, ˜2H); 3.75/3.78 (d of d, J=7.6 Hz, d, 2H); 3.89/3.92 (d of d, J=3.3 Hz, e, 2H); 4.16 (m, f, >1.5H); 4.45 (m, f, <0.5H; may be opposite addition of propylene carbonate); 6.80 (d, J=8.8 Hz, g, 4H); 7.13 (d, J=8.8 Hz, h, 4H). Example 9 Synthesis of Tetramethylspirobisindane Bis(2-Hydroxylpropyl Ether) Dimethacrylate (“SBID POMA”) [0086] A mixture of 5.0 g (11.8 mmol; 23.6 mmol OH) SBID PO from Example 7, 10.0 g (65 mmol) methacrylic anhydride, and 2.0 g (25 mmol) pyridine was stirred in a 50 ml RB flask under air in a 120° C. oil bath for 5 hrs. The solution was cooled to room temperature, added to 100 ml water containing 8 g sodium carbonate, and stirred for 30 mins. The aqueous mixture was briefly shaken in a separatory funnel with 50 ml diethyl ether. The water was separated, and the ether was shaken briefly with 25 ml of water containing 5 ml concentrated HCl. The acidic water was again separated, and the ether layer was shaken briefly with 20 ml of water containing 2 g sodium carbonate. The ether was separated and dried over magnesium sulfate followed by filtration; 5 mg MEHQ was added to the filtrate. The solution was quickly rotovapped from warm water then held under 20 mm Hg vacuum overnight with an air bleed through a syringe needle to yield 7.04 g tetramethylspirobisindane bis(2-hydroxylpropyl ether) dimethacrylate (“SBID POMA”). [0087] 1 H NMR (CDCl 3 ) indicated 80% conversion to dimethacrylate. The ratio of the integrals of the 5.55 ppm methacrylate vinyl proton to the 7.10 ppm aromatic ring proton equaled 0.80. Example 10 Synthesis of Bisphenyl A Bis(2-Hydroxypropyl Ether) Dimethacrylate (“BPA POMA”) [0088] A mixture of 3.8 g (11 mmol; 22 mmol OH) BPA PO from Example 8, 5.0 g (32 mmol) methacrylic anhydride, and 2.0 g (24 mmol) pyridine was stirred in a 50 ml RB flask under air in a 120° C. oil bath for 5 hrs. IR of a sample showed the absence of OH at 3,400-3,500 cm −1 as well as a strong 1,720 cm −1 ester peak. [0089] The mixture was added to 30 ml water containing 1 g sodium carbonate and stirred for 30 mins. followed by extraction with 50 ml diethyl ether. The ether layer was separated and washed with 10 ml water containing 1 ml concentrated HCl, separated again, washed with 5 ml 5% aqueous sodium bicarbonate, and dried over magnesium sulfate. The ether was filtered, and 5 mg MEHQ was added to the filtrate. The solution was quickly rotovapped from hot water and then held under 20 mm Hg vacuum overnight with an air bleed through a syringe needle to yield 4.25 g bisphenyl A bis(2-hydroxypropyl ether) dimethacrylate (“BPA POMA”). [0090] NMR (CDCl 3 ) indicated 85-90% conversion to methacrylate diester by ratio of aromatic ring protons (7.10 ppm) to methacrylate vinyl protons (6.08 ppm). Example 11 SBID POMA/TEGDMA—Glass Composition [0091] A mixture of 1.25 g TEGDMA/photoinitiator masterbatch from Example 5 and 1.25 g SBID POMA from Example 9 was combined in a scintillation vial and mixed with a spatula to a uniform mixture. Then, 0.50 g Degussa OX-50 fumed silica was mixed in with a spatula, followed by 7.0 g silanated Schott 8235 UF1.5 glass powder. The blend was placed on a PTFE sheet and mixed by folding over and flattening out the doughy composition 40 times. The glass-resin blend was held under 40 mm Hg vacuum at room temperature for 16 hr. and then in an oven at 50° C. under 17″ vacuum (330 mm Hg) with an air bleed for 8 hr. This composition contained 25.0 wt % resin, 5.0 wt % fumed silica, and 70.0 wt % glass. The resin-glass blend was molded and cured into bars for physical testing as described in Example 6. Example 12 BPA POMA/TEGDMA—Glass Compostion [0092] A mixture of 1.25 g TEGDMA/photoinitiator masterbatch from Example 5 and 1.25 g BPA POMA from Example 10 was combined in a scintillation vial and mixed with a spatula to a uniform mixture. Then, 0.50 g Degussa OX-50 fumed silica was mixed in with a spatula, followed by 7.0 g silanated Schott 8235 UF1.5 glass powder. The blend was placed on a PTFE sheet and mixed by folding over and flattening out the doughy composition 40 times. The glass-resin blend was held under 40 mm Hg vacuum at room temperature for 16 hr. and then in an oven at 50° C. under 17″ vacuum (330 mm Hg) with an air bleed for 8 hr. This composition contained 25.0 wt % resins, 5.0 wt % fumed silica, and 70.0 wt % glass. The resin-glass blend was molded and cured into bars for physical testing as described in Example 6. Example 13 [0093] Physical tests were performed on the SBID POMA/TEGDMA bars from Example 11 and the BPA POMA/TEGDMA bars from Example 12 as described in Example 6. [0094] As seen in Table 2, use of the bulky monomer with the spirobisindane structure reduced polymerization shrinkage by 15% relative to the bisphenyl A monomer control composition without significantly compromising mechanical properties. TABLE 2 Resin Mixture BPA POMA/ SBID POMA/ (1:1) TEGDMA TEGDMA Shrinkage, % 4.86 4.13 K IC , MPa · m 1/2 1.67 1.56 Flex Strength, 138 102 MPa · m 1/2

The invention relates to a dental composite material wherein space-filling compounds are utilized to reduce shrinkage upon polymerization; the invention also relates to a method for producing dental restoration articles with reduced shrinkage; the invention also relates to various dental restorative articles comprising the aforementioned space-filling compounds.

BACKGROUND OF THE INVENTION I. Field of the Invention The present invention provides novel organic compounds, useful for antifertility purposes. Particularly, the present invention provides a novel polypeptide isolated from the mammalian pineal gland. More particularly, there is provided a novel bovine pineal tripeptide and salts thereof with antigonadotrophic activity. Also provided by the present invention are novel methods for isolation of a bovine pineal tripeptide from the bovine pineal gland. Gonadotropins are a class of substances which stimulate male and female gonads, thus ordinarily representing profertility or fertility-maintaining agents. The gonadotropins include luteinizing hormone (LH) which stimulates ovulation and post-ovulatory progesterone production in the female ovaries. Another gonadotropin, follicle stimulating hormone (FSH), is a secondary pituitary hormone which stimulates the pre-ovulatory maturation of the Graafian follicles of the ovary, thus encouraging estrogen production therein. Thus, both LH and FSH stimulate estrogen or progesterone production and release from the ovaries, and are thereby essential for the establishment and maintenance of fertility. In the male, FSH supports the germinal cells of the testes, while LH stimulates testosterone production. Hence these gonadotropins are essential to spermatogenesis and thus fertility in the male. In addition to LH and FSH an hormonal substance from the hypothalamus, gonadotropin releasing hormone (GnRH), is known to be an endogenous agent for the stimulation of LH and FSH release. This substance is alternately known as LH-RH (luteinizing hormone releasing hormone) or LRF (luteinizing hormone releasing factor). Because the gonadotropins are essential to the maintenance of fertility in both the male and the female, antigonadotrophic substances have been sought for use as antifertility or fertility-suppressing agents. One fruitful source of antigonadotrophic substances has been the mammalian pineal gland, from which two broad classes of antigonadotrophic compounds have been isolated: polypeptides and indoles. With regard to the latter class, the most widely examined antigonadotrophic substance is melatonin, which, inter alia, reduces the effects of MSH (melanocyte stimulating hormone). Other pineal-derived antigonadotrophic indoles include serotonin, 5-hydroxytryptophol, 5-methoxytroptophol, and N-acetylserotonin. With regard to pineal antigonadotrophic polypeptides, one important such substance is arginine vasotocin, which was first isolated by Milcu, S.M., et al., Endocrinology 72:563-566 (1963). For the structure of arginine vasotocin, see Cheesman, Biochim. Biophys. Acta. 207:247-253 (1970) and German offenlegungsschrift 2,739,492, published Mar. 3, 1978 (Derwent Farmdoc CPI No. 18163A). Various other pineal antigonadotrophic polypepetides have been reported by various workers. For a brief review of reports of such polypepetides, see Table 3 (pages 164-166 of Reiter, Russell J., et al., "Pineal Antigonadotrophic Substances: Polypeptides and Indoles", Life Sciences 21:159-172 (1977). A further review of pineal antigonadotrophic polypeptides, particularly a disclosure of certain uncharacterized (e.g., no amino acid content or amino acid sequence) polypepetides is provided by Orts, R.J., et al., "Antifertility Properties of Bovine Pineal Extracts: Reduction of Ovulation and Pre-Ovulatory Luteinizing Hormone in the Rat", Acta. Endocrinologica. 85:255-234 (1977), and Orts, R.G., "Reduction of Serum LH and Testosterone in Male Rats by a Partially Purified Bovine Pineal Extract", Biology of Reproduction 16:249-254 (1977). II. Prior Art The existence of pineal antigonadotrophic polypeptides and their antifertility properties is known in the art. See Orts, R.J., et al., "Antifertility Properties of Bovine Pineal Extracts: Reduction of Ovulation and Pre-Ovulatory Luteinizing Hormone in the Rat", Acta Endrocrinologica. 85:225-234 (1977), and Orts, R.J., "Reduction of Serum LH and Testosterone in Male Rats by a Partially Purified Bovine Pineal Extract", Biology of Reproduction 16:249-254 (1977). Moreover, a general review of both polypeptide-type and indole-type pineal anti-genadotrophic substances is provided by Reiter, Russell J., et al., "Pineal Antigonadotrophic Substances: Polypeptides and Indoles", Life Sciences 21:159-172 (1977), cited above. SUMMARY OF THE INVENTION The present invention provides novel compositions of matter. In particular, the present invention provides a novel composition of matter consisting essentially of a pineal antigonadotrophic polypeptide. The present invention further provides novel methods for the isolation of a pineal antigonadotrophic polypeptide substantially free from all other pineal-derived substances. Most particularly, the present invention provides: (a) a bovine pineal antigonadotrophic polypeptide, being substantially free from all other pineal-derived substances, which is characterized by the amino acid sequence: threonine-serine-lysine; and (b) the pharmacologically acceptable carboxy salts and acid addition salts of the tripeptide characterized by the amino acid sequence: threonine-serine-lysine. The carboxyl-terminated residue of the bovine pineal antiqonatrophic tripeptide is lysine and the N-terminus is threonine. The bovine pineal antigonadotrophic tripeptide of the present invention is prepared by a novel process, described in detail by Example 1 hereafter, which comprises a further aspect of the present invention. Because of the purity and homogeneity of the bovine pineal antigonadotrophic tripeptide in accordance with the present invention, it represents a surprisingly and unexpectedly improved antifertility agent, as compared with previously known bovine pineal antigonadotrophic polypeptide compositions. Thus, while the novel bovine pineal antigonadotrophic tripeptide is useful for the same antigonadotrophic (therefore antifertility) purposes as the prior art compositions, smaller dosages and fewer untoward side effects are evidenced when the novel compositions are employed for pharmaceutical purposes. Even more strikingly, the provision of a single and strikingly active tripeptide in accordance with the present invention advantageously permits the chemical synthesis of the tripeptide from its amino acid constituents. Such a chemical synthesis is readily accomplished by methods known in the art. Thus, the present invention permits the induction of antifertility effects of the bovine pineal antigonadotrophic polypeptide factors to be made widely available without reliance on the comparatively tedious and uneconomic procedure of extraction from mammalian sources. The novel pineal antigonadotrophic tripeptides in accordance with the present invention are employed whenever the induction of an antigonadotrophic effect is indicated. While, as indicated above, such antigonadotrophic effects are typically antifertility effects, the present invention also provides for antigonadotrophic effects which are essentially pro-fertility (e.g., estrous regulation in non-primates), or merely secondarily related to fertility (e.g., management of steroid-supported carcinoma). The bovine pineal antigonadotrophic tripeptides of the present invention are useful in both humans and valuable domestic animals, including zoological specimens. The dosages employed are those wherein effective suppression of gonadotrophic hormones is achieved. The actual suppression of the gonadotropins is readily determined in any patient or animal by measuring changes in serum levels of these hormones, by known (e.g., radioimmunoassay) techniques. While the effective dose for a particular patient or an animal will depend upon the species, sex, age, indication, and condition of the subject, ordinarily an acute dosage of between 1 and 1,000 ng/kg, intravenously, is effective to suppress gonadotrophic activity. In those indications where sustained depression of gonadotrophic activity is required, subsequent and periodic doses of the bovine pineal antigonadotrophic tripeptides are administered. The precise regimen for administration can be readily adjusted for any patient or animal based upon serum levels of gonadotrophic hormones or subjective indices of response. The pineal antigonadotrophic tripeptides are administered by any convenient route of administration (e.g., subcutaneously, intramuscularly, vaginally bucally, intranasally, or orally) with equivalent dosages to those referred to above for intravenous administration. Equivalent dosages refer to those dosages by such other routes of administration as provides equivalent systemic (e.g., serum) levels of the tripeptide and equivalent suppression of gonadotrophic hormones. Accordingly routes of administration other than intravenous ordinarily require substantially increased dosages of the tripeptide. For example, the intramuscular dose will range from 2 to 10 times the intravenous dose, while the oral dose will in most cases be significantly higher than the intramuscular dose. In any case the appropriate equivalent dosage is determined by patient or animal response (i.e., gonadotropin suppression). For the various routes of administration, conventional dosage forms are employed. Accordingly, sterile solutions are employed where parenteral administration is selected, while suppositories are conveniently used when vaginal or rectal routes of administration are selected. When oral routes of administraton are selected, enteric-coated tablets or capsules will represent a preferred dosage form in those cases where variations in gastric pH would create unpredictability in the rate of tripeptide absorbed versus the rate of gastric hydrolysis. Regarding the indications for use of the novel bovine pineal tripeptides in mammalian males, administration of an antigonadotrophic amount results in a significant reduction of or cessation of spermatogenesis, thereby abolishing male fertility. Since the effect on spermatogenesis is accompanied by a decrease in testosterone levels, supplemental androgenic steroid therapy may be indicated to restore libido. However, in those patients and animals where diminished libido and the associated behavioral changes are a desirable additional effect of the tripeptide, no additional androgenic steroid therapy is indicated. Patients within the latter category would include those in certain institutions (e.g., prisons and mental hospitals), while animals within the latter category would include canine and feline species where the effect of the tripeptide would be tantamount to a reversible castration. Since an effective male antispermatogenic or antifertility agent requires that drug be delivered chronically, one preferred method of administration for this and other chronic indications is by a prolonged-release formulation or a prolonged-release device. Many such devices, e.g., comprising a drug reservoir surrounded by a controlled release rate membrane, are applicable for the chronic and controlled release of the novel bovine pineal antigonadotrophic polypeptides of the present invention. A second preferred method for chronic administration is in the food or feed of the patient or animal being treated. In female mammals, suppression of gonadotrophic hormones is effective to (1) prevent ovulation, and (2) reverse any CL progesterone-supported pregnancy. With regard to the first of these uses, suppression of ovulation in humans is accomplished by administering the novel pineal antigonadotrophic tripeptide from the time of menses to about three weeks after the initiation of the menses. In estrous-cycling animals the novel pineal antigonadotrophic tripeptides are administered chronically to prevent ovulation. With regard to the reversal of CL-supported pregnancy, in those animals where a functioning corpus luteum (CL) is required for the maintenance of pregnancy, the administration of the novel pineal antigonadotrophic tripeptide after conception will either prevent implantation or reverse fetal implants, thereby reversing early pregnancy. For this purpose, the pineal antigonadotrophic tripeptide is given, for example, in humans over several days, beginning prior to the next anticipated menses. In non-primates the time initiation of treatment ranges from immediately post-conception to midterm and continues over several days. In estrous-cycling mammals, the novel pineal antigonatrophic tripeptide is useful in the regulation or synchronization of the estrous cycle, by regression of the corpus luteum. For this purpose, the timing during the estrous cycle of the pineal antigonadotrophic tripeptide administration is similar to that employed by other corpus luteum-regressing or luteolytic agents (e.g., the prostaglandins). Thus in the polyestrous animal the treatment is continued for about one-half of a single cycling period and ovulation will then occur at a predetermined time thereafter. In addition to the pro-fertility effects of estrous regulation, mammals infertile because of a persistent corpus luteum may also be brought into estrus and successfully bred after treatment with the pineal antigonadotrophic tripeptides of the present invention. In addition to the various fertility-related indications recited above, certain other non-fertility uses of the pineal antigonadotrophic tripeptides include the treatment of precocial puberty, and steroid-supported carcinoma. These disease states, which often require the removal of the gonadotropin-producing gland (pituitary) or the gonads themselves, are thus non-surgically treated in accordance with the present invention. In those cases where sustained supression of gonadal function is desired (e.g., steroid-supported carcinoma of the breast or prostrate), the prolonged-release formulations or devices described above are employed. As indicated above, any of the various pharmacologically acceptable carboxy salts or acid addition salts of Thr-Ser-Lys are used in accordance with the present invention. These salts are respectively prepared from the tripeptide of Example 1, below, by mixture with a dilute solution of the base or acid corresponding to the carboxy or acid addition salt to be prepared. Thereafter the salts are recovered in solid form by conventional techniques, i.e., concentration under reduced pressure. Among the pharmacologically acceptable carboxy salts in accordance with the present invention are various metal salts, including alkali and alkaline metal salts, and heavy metal salts. Also, amine salts, including primary and secondary and tertiary amine salts, are included, as well as the quaternary ammonium salts. With regard to the acid addition salts, there are included conventionally employed acid salts of pharmaceuticals, such as the hydrochloride and hydrobromide salts. As is apparent, however, from the above list, suitable salts for use in accordance with the present invention are characterized only by the absence of substantial toxicity and suitability for pharmaceutical formulation. DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLE 1 Threonine-serine-lysine from the bovine pineal gland A. Fresh bovine pineal glands (120 g) are lyophilized and thereafter homogenized in acetone (100 ml) with stirring for 4 hr at 4° C. The resulting residue is then filtered, washed with acetone (20 ml) and concentrated under reduced pressure at 55° C. The resulting powder is then dispersed in 2.0 N acetic acid (30 ml) and stirred for one hr at ambient temperature. Thereafter the resulting acetic acid mixture is centrifuged at 16,300 g for 2 hr and the supernatant collected and lyophilized. This residue is then dissolved in glacial acetic acid (20 ml), stirred for 45 min at ambient temperature, and centrifuged at 12,000 g for 30 min. Thereafter the supernatant is diluted with distilled water (50 ml) and lyophilized. The resulting residue is then dissolved in 1.0 N acetic acid (10 ml) and centrifuged at 48,200 g for one hr. B. Following the above mild acid extractions, the final supernatant of Part A is lyophilized and the residue dissolved in 0.06 M acetic acid (3 ml of acid per 100 g of residue), pH 3.0, and placed on a column (30 cm×1.5 cm) of analytical grade polystyrene cation exchange resin, Dowex 50[H+], prewashed successively with 2 N sodium hydroxide, distilled water, 2 N hydrochloric acid, and distilled water. Elution successively with water (75 ml), 0.2 M aqueous pyridine (pH 4.0, 75 ml), 0.2 M pyridine (pH 5.0, 150 ml) and 1 M pyridine (pH 7.5-8.5, 75 ml) yields in the 1 M pyridine fractions a product which is collected and lyophilized. The resulting residue is then dissolved in 1% aqueous ammonium bicarbonate (NH 4 HCO 3 ) and placed on a column (80 cm×1.5 cm) of cross-linked dextran gel (Sephadex G25 Fine), equilibrated with 1% aqueous ammonium bicarbonate at ambient temperature. Elution of a column with 1% aqueous ammonium bicarbonate at a flow rate of 45 ml/hr, collecting 4 ml fractions, yields a crude product A in fractions 30-36. This crude product is then lyophilized and the residue dissolved in water. C. The aqueous mixture of Part B is then further purified by vertical flow paper electrophoresis. The crude product in the aqueous mixture is spotted on the paper and run for 30 min at 3,000 v in a mixture of pyridine, acetic acid, and water (100:4:900), pH 6.5. In fraction 4 (of 16 fractions running from cathode to anode), the R L is 0.77-0.83 wherein R L is the ratio of the migration distance of the fraction of interest to that of lysine during the vertical paper electrophoresis. This fraction is then eluted with water and subsequently lyophilized. D. The residue of Part C is then dissolved in water and further purified by descending paper chromatography for 10 hr using butanol, acetic acid, and water (5:1:4) as a solvent system and 3 mm Whatman chromatography paper. From this chromatogram, a fraction whose R f is 0.15-0.22 is eluted and lyophilized. The resulting residue provides the bovine pineal antigonadotrophic tripeptide threonine-serine-lysine substantially free from all other pineal-derived substances. E. The amino acid sequence of the tripeptide of Part D is determined by the Edman degradation procedure described by Salnikow, J., et al., J. Biol. Chem. 248:1480. EXAMPLE 2 Effects of threonine-serine-lysine on mammalian species A. Compensatory Ovarian Hypertrophy (COH) is an effect in standard laboratory (mammalian) animals for assessing antigonadotrophic activity by determining the increase in weight of the remaining gonad after unilateral gonadectomy. Procedures for COH measurement in female rats are described in Ramirez, V.D., et al., Endocrinology 95:475 (1974). According to these known procedures threonine-serine-lysine, prepared in Example 1, is administered intraperitoneally to adult female mice on the same day as a unilateral ovariectomy is performed. On day 5, both experimental and control animals are sacrificed and mean ovarian weights are obtained. The results of this study, reported in Table I below, indicate that the COH or compensatory ovarian hypertrophy (i.e., the difference in ovarian weights as a percentage of the weight of the gonadectomized ovary) is reduced in a dose-dependent manner in animals treated with the threonine-serine-lysine. TABLE I______________________________________Reduction of Compensatory Ovarian HypertrophyDose (ng) COH (± SE)______________________________________Control 45.5 ± 5.3186.1 34.6 ± 6.8372.2 11.1 ± 15.1______________________________________ B. The effect of threonine-serine-lysine on serum concentrations of FSH in the adult female rat is measured 24 hr after intraperitoneal injection of threonine-serine-lysine to unilaterally ovariectomized mice. On day 5 after injection, the animals were sacrificed and ovarian weights recorded There are then determined compensatory ovarian hypertrophy (5 days after treatment) as well as the serum FSH (24 hr after treatment). The results of this study are reported in Table II below. TABLE II______________________________________Effect of Threonine-Serine-Lysineon Compensatory Ovarian Hypertrophyand Serum FSH in Female MiceNo. ofanimals Dose (ng) COH (± SE) Serum FSH (± SE) ng/ml______________________________________6 Control 29.7 ± 8.4 296.8 ± 3758 35.1 12.6 ± 10.9 254.4 ± 88.78 70.3 21.9 ± 8.0 377.0 ± 56.98 175.7 12.9 ± 5.0 165.0 ± 22.58 351.7 21.1 ± 7.8 179.0 ± 60.9______________________________________ C. The antifertility effects of threonine-serine-lysine on the male rat are measured by their ability to inhibit GnRH-or gonadotropin releasing hormone-induced rise in FSH when threonine-serine-lysine is administered intravenously. In this test, both control and tripeptide-treated animals received GnRH in a phosphate buffered saline solution, followed by the administration of the tripeptide in the same buffer. Five animals each were in one control and three tripeptide-treated groups, with the results reported in Table III indicating FSH suppression. TABLE III__________________________________________________________________________Reduction of Serum FSH in GnRH-treated Maleby Threonine-Serine-Lysine Mean concentration of plasma FSH (ng/ml ± SE) ng/mlDose (ng) 0 min 15 min 30 min 60 min__________________________________________________________________________Control 362.5 ± 20.7 1753.4 ± 450.6 1701.6 ± 720.6 247.8 ± 14.01.48 302.2 ± 26.2 338.4 ± 38.8 592.5 ± 217.6 586.5 ± 301.314.8 45.6 ± 52.3 402.9 ± 117.7 472.7 ± 76.9 684.5 ± 142.0148 43.9 ± 85.6 646.1 ± 198.0 1407.8 ± 499.6 1279.6 ± 180.8__________________________________________________________________________

The present invention relates to a bovine pineal tripeptide, exhibiting the amino acid sequence: Thr--Ser--Lys wherein Thr is threonine, Ser is serine and Lys is lysine, and pharmacologically acceptable carboxy and acid addition salts thereof. The invention provides for the isolation of this tripeptide substantially free from all other pineal gland substances, including the various pharmacologically active pineal indoles and polypeptides. Also provided are methods for using this bovine pineal tripeptide for antifertility purposes.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation in part of U.S. patent application titled “Game Machine,” Ser. No. 08/919,016, filed Aug. 27, 1997, pending, the contents of which are hereby incorporated by reference. FIELD OF THE INVENTION The present invention relates to the field of game machines, and more particularly to the field of game machines such as slot machines in which unusual lighting, sounds, or any other similar indicator signals that a player may most likely win a prize. BACKGROUND Game machines, such as slot machines and poker game machines, that pay back tokens, such as coins, for winning game results have been very popular. Here, slot machines will be used as an example of a game machine. Players start a game by pulling a start lever after putting a token in the slot machine. A plurality (three, for example) of reels with numerous types of symbols arranged on the circumference rotate at high speed in the slot machine, and the prize status is determined by the combination of the symbols on the reels displayed at a given location in a window when the reels have stopped. The number of tokens that are paid out is determined by the combination of symbols when the reels have stopped, that is, the prize status. When the current game prize status has been determined, the reels are rotated to begin the game. Slot machine prizes typically include “Big Jackpots,” where 1000 or more tokens, for example, are paid back, as well as “Small Jackpots,” where less than 1000 tokens are paid back. A variety of other prizes also may be offered. In most slot machines, the player can operate stop buttons provided in the slot machine to stop the reels, but in the type of slot machine in which the prize status is determined by random selection using random numbers for each game, the reels are not stopped immediately when the player actuates the stop buttons, but instead are stopped when the symbols on the reels reach the position corresponding to the prize status previously determined by random selection. It is possible for too much time to pass after the player presses the stop buttons until the reels stop at the prize status that had been previously determined by random selection. This could lead to unnatural reel-stopping operations. In such cases, the reels may be stopped at a point that does not match the prize status previously determined by random selection. In other words, when too much time passes until the reels stop after the player has operated the stop bottons, leading to unnatural reel-stopping operations, the reels are stopped irrespective of the prize status previously determined by random selection. As a result, even when the prize status previously determined by random selection would have been, for example, a “Big Jackpot,” the prize status may end up being a “Lose” due to the timing with which the player has actuated the stop buttons. Conversely, when the prize status previously determined by random selection would have been a “Lose,” the prize status may end up being a “Big Jackpot” due to the circumstances under which the player actuated the stop buttons. Slot machine prizes also may include a so-called “Second Game Win” result, where a second game can be played as a subsidiary game. This “Second Game Win” result is described below. The game that results in the aforementioned “Big Jackpot,” “Small Jackpot,” or “Second Game Win” is referred to herein as the first game. When a “Second Game Win” is won in a first game, a second game can be played without new tokens being entered. The second game is played with an arrangement or a set of beginning reels that is different from the arrangement or set of the first game. Common examples are referred to as “Bonus” games or “Free” games. Such a second game is often advantageous for the player, allowing the player to win a prize that includes a large amount of tokens depending on the results of the second game. The player plays the slot machine in anticipation of increasing the number of tokens in possession, but since the number of tokens in the player's possession does not increase all that much with “Small Jackpots,” the player plays the slot machine while hoping for a “Second Game Win” or a “Big Jackpot” that will quickly increase the number of tokens in the player's possession. Frequently, the prize status in a slot machine is determined by random selection using random numbers for each game. In this type of slot machine, for example, the prize status is randomly selected when a token is put into the slot machine and the start lever is pulled, and the current game prize status is then determined. When the current game prize status has been determined, the reels are rotated to begin the game. However, in the type of slot machine in which the prize status is determined by random selection using random numbers for each game, the prize status is randomly selected when a token has been put into the slot machine and the start lever has been pulled, so the prize status of the current game is already known when the reels begin to rotate. As described above, the player plays slot machines hoping for a “Second Game Win” or “Big Jackpot” to quickly increase the number of tokens in the player's possession, and when it is known that there is an extremely high possibility that the current game will result in a “Big Jackpot” or “Second Game Win” as a result of previous random selection (as described previously, there can be cases in which the prize status might end up as a “Lose” due to the timing with which the player actuates the stop buttons), it would be extremely significant to make a demonstration alerting the player to that fact. SUMMARY OF THE INVENTION The systems and methods described herein are designed to provide a game machine which can make demonstrations when a “Second Game Win” has been obtained by random selection for determining the game prize status, and which can make more effective demonstrations when a “Second Game Win” has been obtained. A game machine according to the systems and methods described herein randomly selects the game result conditions of a first game by lottery from among a plurality of conditions, and determines the game results on the basis of the randomly selected results, wherein the game machine is characterized by alerting a player by a demonstration to the fact that there is “Second Game Win” condition among the randomly selected conditions. The presentation includes various states or features, such as changes in the rotating operation of the reels, visual stimulation by special light displays, audio stimulation by special sounds, and tactile stimulation by vibrations in the operating components of the machine. Naturally, two or more states or features can be combined. A game machine according to the systems and methods described herein includes random selection means for randomly selecting, at the beginning of the current first game, game result conditions for a predetermined prescribed number of games from among the plurality of such conditions, storage means for storing a prescribed number of game result conditions; actuating means for actuating the start of a game, determination means for determining whether or not a “Second Game Win” condition is present among the randomly selected results for a prescribed number of games, and demonstration means for displaying prescribed sensory information to the player when the “Second Game Win” condition is present. This sensory information may include visual, audio, and tactile information, either independently or in combination, similar to that described above. A game machine optionally may include second random selection means for randomly selecting in advance several kinds of current game result conditions at the beginning of the current first game, selecting one of the several kinds of randomly selected results by a prescribed method, and actualizing the current game results, wherein a demonstration is made during the current game when the aforementioned “Second Game Win” condition is present among the several kinds of conditions randomly selected in advance. Optionally, a demonstration may be made when the randomly selected game results include at least two predetermined game results, or some combination of predetermined game results. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates the appearance of a slot machine in an embodiment of the present invention. FIG. 2 is a detail of the window for viewing the reels of the slot machine depicted in FIG. 1 . FIG. 3 is a flow chart of the process for determining active prize lines. FIG. 4 is a flow chart of the basic game progress of a slot machine according to the present invention. FIG. 5 is a flow chart of the process from the determination of the prize to the pay out of tokens. FIG. 6 is a block diagram depicting a microcomputer controlling a slot machine according to the present invention. FIG. 7 is a flow chart describing the operation of a slot machine in an embodiment of the present invention. FIG. 8 is an illustration of the structure of the random number store in an embodiment of the present invention. FIG. 9 is a flow chart of the operation of the slot machine in another embodiment of the present invention. FIG. 10 illustrates the structure of the random number store in another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In conventional types of slot machines in which the prize status is determined by random selection using random numbers for each game, when the prize status resulting from random selection in the current game is a “Big Jackpot,” a demonstration is made by unusual operations, such as unusual lights or sounds, but there is no demonstration when the prize status resulting from the random selection in the current game is a “Second Game Win.” In the conventional slot machines described above, the results are randomly selected using random numbers for each game, so only the current game prize status is known. Thus, demonstrations are made only when the randomly selected result of the current game is a “Big Jackpot,” and there are a fewer number of demonstrations when there are “Big Jackpots.” There is thus a problem in that the demonstrations are not very effective in arousing the interest of the player to play more games. The present invention is described below with reference to the drawings. Here, a slot machine is described as an example of a game machine according to the present invention. However, the present invention is not limited to slot machines, and may be used for any type of game machine in which game results can be randomly selected. FIG. 1 illustrates the appearance of a slot machine in an embodiment of the present invention. The slot machine in FIG. 1 includes a main unit 1 . A cabinet 2 having a front face constituting the entire main unit 1 is provided with windows 3 L, 3 C, 3 R corresponding to a plurality of reels 4 L, 4 C, 4 R, (three in the case of FIG. 1 ), for viewing the symbols on each of the reels 4 L, 4 C, 4 R located inside the cabinet 2 . A speaker 16 and one or more lights 18 is included on a display panel 15 , or may be placed elsewhere on the main unit 1 . Changes in the tone, volume or nature of the sounds may be broadcast through speaker 16 , or changes in the color or timing of the light 18 , or some combination thereof, may be used to demonstrate the prize status, i.e., the likelihood of winning a prize, to the player. Alternatively, static or moving text, numbers, or designs could be illuminated in a portion of the display panel 15 or on the main unit to indicate to the player that there is an increased likelihood of winning a “Big Jackpot”. A start lever 5 for rotating the reels 4 L, 4 C, 4 R when operated by a player is rotatably attached at a prescribed angle on a side face of the cabinet 2 . A token inlet 6 for entering tokens and a digital display 7 , comprising a credit number display 7 A for displaying the number of tokens currently credited and a prize number display 7 B for displaying the number of tokens won in the current game, are provided on the lower right side of the windows 3 L, 3 C, 3 R on the front face of the cabinet 2 . Arranged below the windows 3 L, 3 C, 3 R on the front face of the cabinet 2 are a spin switch 8 for setting the reels 4 L, 4 R, 4 C in motion by the operation of a push button which is separate from the operation of the start lever 5 , a single bet switch 9 for betting just one token from among the credited tokens on the game when the push button is pressed once, a maximum bet switch 10 allowing the maximum possible number of tokens to be bet on a single game when the push button is pressed once, a “C/P” switch 11 for switching between play credit/pay out of the tokens won by the player when the push button is pressed, and a token receptacle 13 for receiving tokens paid out from a token pay outlet 12 at the bottom of the front face when the “C/P” switch 11 is switched. FIG. 2 is a detailed view of the window for viewing the reels 4 L, 4 R, 4 C of the slot machine depicted in FIG. 1 . In this example of a slot machine, the number of prize lines can be selected according to the number of tokens entered (number of tokens bet on the game) prior to the start of the game. That is, in FIG. 2, three symbols “S” on each reel can be seen through the windows 3 L, 3 C, 3 R. When one token is entered, only a single line 21 is activated per prize determination; when two tokens are entered, a total of three lines comprising lines 21 , 22 A, and 22 B are activated per prize determination; and when three tokens are entered, a total of five lines comprising lines 21 , 22 A, 22 B, 23 A, and 23 B are activated. In FIG. 2, a set of lamps 14 a , 14 b , 14 c , 14 b′ , 14 c′ , which are marked with the characters “1”, “2”, and “3”, lights up to display the lines that have been activated according to the number of tokens entered. The selection of the number of active lines is determined, for example, by the number of tokens entered prior to the operation of the start lever 5 or the spin switch 8 . The display lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′ are connected so as to light up to display the lines that have been activated according to the number of tokens entered. Thus, the selection of the number of active lines is determined by the number of tokens entered prior to the operation of either the start lever 5 or the spin switch 8 , or, alternatively, by the number of tokens entered after the operation of the start lever 5 and prior to the operation of the spin switch 8 . When one token is entered, only one line, which is associated with one display lamp 14 a and mark “1”, is activated per prize determination; when two tokens are entered, a total of three lines, which are associated with three display lamps 14 a , 14 b , 14 b ′ and the marks “1” and “2” are activated per prize determination; and when three tokens are entered, a total of five lines, which are associated with all five of the display lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′ and with the marks “1”, “2” and “3”, are activated. This selection is done in accordance with the flowchart shown in FIG. 3 . The selection of the number of active lines may be based on a microswitch, photosensor, or other such electrical signal-based device for detection of the insertion of a token and the determination as to whether or not the start lever 5 or spin switch 8 has been operated. In the “active line” process in FIG. 3, one or more of the display lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′ are turned on, and at the same time, a signal is input to the microcomputer described below so as to be taken into account during the determination of the prize. FIG. 3 is a flowchart 100 illustrating the selection of lines to activate by lighting up one or more of the lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′. The selection may be made using a microswitch, a photosensor, or another similar electrical signal-based system for detection of the insertion of a token and determination as to whether or not the start lever 5 , or the spin switch 8 , or both, have been operated. In the flowchart 100 , the line activation process starts at a step 101 indicating conclusion of a prior game. Following the step 101 is a test step 102 that determines whether a token has been entered. The test step 102 is repeated until a token is entered. Once a token has been entered, control passes to a step 104 so that a single display lamp 14 a will be lit to activate a single line, which is marked with a “1” in FIG. 1 . Following the step 104 is a test step 106 that determines whether the start lever 5 has been pulled. If the start lever 5 has been pulled, then the game proceeds to a game start step 120 and the game starts. Otherwise, a test step 108 determines whether a second token has been entered. The test steps 106 , 108 are repeated until either the start lever 5 is pulled or a second token is entered. If a second token is entered, control passes to a step 110 that indicates that two more lamps 14 b , 14 b ′ will be lit to activate two more lines, which are marked with a “2” in FIG. 1, for a total of three lines activated. Following the step 110 , a test step 112 is performed to test whether the start lever 5 has been pulled. If the start lever 5 has been pulled, control passes from the step 112 to the game start step 120 . Otherwise, a test step 114 is performed to determine whether a third token has been entered. The steps 112 , 114 are repeated until either the lever 5 is pulled or a third token is entered. If a third token is entered, two more display lamps 14 c , 14 c ′, which are marked with a “3” in FIG. 1, will be lit to activate two more lines, for a total of five lines activated. A test step 118 is then performed to determine whether the start lever 5 has been pulled. If the start lever 5 has been pulled, then control passes to the game start step 120 . Otherwise, the test step 118 is repeated. In the “active line” process shown in FIG. 3, one or more of the display lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′ are turned on depending on the number of tokens entered, and, at the same time, a signal is input to the microcomputer, as described below, so that the number of token entered is taken into account during the determination of the prize. After the number of prize lines has thus been determined, the game basically progresses according to the flow chart in FIG. 4 . That is, the game starts when the start lever 5 or spin switch 8 is operated, the three reels rotate, the prize status described below is randomly selected after a prescribed period of time has passed, the reels automatically stop based on the randomly selected results, and the current game is terminated. FIG. 4 is a flowchart 200 illustrating progress of the game once the number of prize lines has been determined in accordance with the process shown in FIG. 3 (or by following one of a variety of conventional processes equivalent to that shown in FIG. 3 ). The game begins at the game start step 120 (of FIG. 3 ). A reel rotation step 202 follows the start step 120 . Following the reel rotation step 202 is a delay step 204 . Following the delay step 204 is a result selection step 206 in which the results for a plurality of games are randomly selected to provide a random selection of prize status. Following the result selection step 206 is a reels stop step 221 in which the reels are stopped, optionally in response to a player's pressing of stop buttons. After the step 221 , control passes to a game end step 224 . When the game is over, the process for determining the prize is carried out according to the flow chart in FIG. 5, for example, and tokens are paid out when a prize has been won. During the determination of a prize, photoelectric signal components provided for the symbols on the reels are read by photosensors, for example, or signal components may be provided at locations on the reels so that reset pulses are obtained for each reel rotation by pulse motors that drive the reels, allowing it to be determined whether a pulse signal has been supplied for any pulse to the pulse motor until the reels are stopped following the production of the reset pulse. FIG. 5 is a flowchart 300 illustrating the determination of the prize when the game is over. Following the game end step 224 (of FIG. 4 ), control passes to a step 312 in which determination of the prize is made. Following the step 312 is a test step 314 which tests whether a prize was won. If so, control passes to a step 316 . Otherwise, control passes to the game over step 101 (of FIG. 3 ). In the step 316 , the prize tokens are paid out in the proper amount. Following the step 316 is a test step 318 in which it is determined whether the paying out has been completed. If so, control passes to the game over step 101 . Otherwise, control returns to the step 316 and the process is repeated until the game over step 101 is reached. FIG. 6 is a block diagram depicting the microcomputer controlling the slot machine in the present embodiment. In FIG. 6, the broken line block A is a main control component having a main CPU 50 , a ROM 51 , and a RAM 52 . The ROM 51 stores a correspondence table of the symbols described above and symbol codes, a table of symbol codes corresponding to prizes and the number of prize tokens paid out, as well as prize probability tables and the like according to prize status when a prize is awarded for the game that has been run. The RAM 52 prepares random number stores for temporarily storing random numbers sampled after the start of a game, memory for temporarily storing data such as rotating reel code numbers and symbols, and the like. A clock pulse generator 53 generates, for example, a four MHZ pulse, and that actuates the main CPU 50 based on this standard pulse, and a divider 54 gives an interruption pulse of 500 Hz, for example, to the main CPU 50 for the interrupt execution process of a prescribed program. A sound generator 55 is driven so as to produce sounds by means of a speaker 56 in order to enhance game interest at prescribed periods after the start of the game. The speaker 56 can be used as the demonstration means described below. An LED drive component 57 drives a 7-segment digital display light-emitting diode 58 , for example. This diode 58 can be used to display the number of tokens paid out or the like. The broken line block B in FIG. 6 is a reel drive view block. In this embodiment, reels 4 L, 4 C, 4 R are driven by pulse motors 28 L, 28 C, 28 R. The motors 28 L, 28 C, 28 R are rotated by drive pulses from a motor drive component 60 . For example, the reels are rotated one reel symbol at a time, as seen through windows 3 L, 3 C, 3 R, per pulse. The reels are constructed in such a way that a reset signal is produced per rotation. The reset signals are detected by a detection block 61 . In the main CPU 50 , the reset signals are detected by the detection block 61 , and the number of drive pulses given to the motor is then counted, allowing the reel symbols visible in the windows 3 L, 3 C, 3 R to be specified. In the prize determination, the symbols of the reels are used as code signals as described above, and the combination is matched with the ROM described below. A prize token pay out hopper 70 and a hopper motor drive component 71 also are shown. A token detector 72 detects the insertion of tokens prior to the start of the game. When a prize has been won, the hopper motor for paying out prize tokens is driven to pay out the prize tokens. The tokens that are paid out are counted, for example, by the token counter 72 located in the token pay out chute, and the game is over when the prescribed number of tokens has been reached. The signal for the number of tokens paid out from the hopper 70 and the signal for the number of tokens entered from the token detector 72 are sent via a “Sw” input component 75 and main CPU 50 from a count drive component 76 to a counter or lamp 77 , the number of tokens entered or paid out is detected, or one or more of the display lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′ for the active prize lines are lit up according to the number of tokens entered. The display lamps 14 a , 14 b , 14 c , 14 b ′, 14 c ′ can also be used as the demonstration means described below. When three tokens are entered, a lock solenoid 73 that locks the entered tokens is driven. Another switch operating component 78 , such as a stop switch or the like, is operated when a player wishes to stop a game after a token has been entered. A start signal generator 79 is constructed, for example, of the aforementioned start lever 5 or spin switch 8 . The system structure described above allows the determination process for the basic progress of the game shown in the flow charts above to be carried out by the prescribed executing program using the main CPU 50 . The method for randomly selecting the prize status and the method for determining whether or not a demonstration is to be put on, which are features of this embodiment, are described below. The prize status is randomly selected as a result of a match between the random number values sampled at the start of the game, as described above, and the groups of numerical values for awarding a prize which are stored in the prize table in the ROM. FIG. 7 is a flow chart describing the operation of the slot machine in the present embodiment. FIG. 8 is an illustration of the structure of the random number store in the present embodiment. FIG. 7 is a flowchart 400 describing one possible method of operation of the slot machine in an embodiment of the present invention and FIG. 8 is an illustration of the structure. Turning first to FIG. 7, the operation process begins at an all clear step 401 . Following the step 401 is a step 402 in which random numbers are sampled for four games and stored in a random number store (shown in FIG. 8 and described below). Following the step 402 is a game start step 404 in which the game starts. Following the step 404 is a test step 406 in which a test is made to determine whether a token has been entered. If so, control passes to a test step 408 . Otherwise, the test step 406 is repeated. In the test step 408 , it is determined whether the start lever 26 is on. If so, control passes to a test step 410 . The test steps 406 , 408 are repeated until either the start lever 26 is on or a token is entered. In the test step 410 , a determination is made whether there is a “Second Game Win” result. If so, control passes to a step 412 in which a demonstration flag is set, and, following the step 412 , control passes to a step 414 . Otherwise, control passes from the step 410 to the step 414 and thus the demonstration flag is not set. In the step 414 , a first random number is extracted from the random number store to determine the prize status. Following the step 414 is a step 416 in which the random numbers in the random number store are shifted, as described below. Following the step 416 is a step 418 in which a random number for one game is sampled. Following the step 418 is a step 420 in which the random number sampled in the step 418 is stored in the fourth random storage number area of the random number store. Following the step 420 is a test step 422 in which it is determined whether the demonstration flag is ON. If so, control passes to a step 424 in which reel rotation starts in a staggered manner. Otherwise, control passes to a step 426 in which reel rotation starts in a normal manner. Following each of the steps 424 , 426 is a step 428 , in which the demonstration flag is cleared when all reels stop rotating. Following the step 428 , control passes to the game over step 101 . When, for example, the main power source switch of the slot machine is turned on, or when a clear switch not shown in the figures is switched ON, the entire system is initialized, the random numbers stored in a random number store 80 shown in FIG. 8 are cleared, and the demonstration flag is cleared. As shown in FIG. 8, the random number store 80 has four random number areas: a first random number area 81 , a second random number area 82 , a third random number area 83 , and a fourth random number area 84 , in which the four random numbers comprising random number α, random number β, random number γ, and random number δ can be stored. The random number stored in the first random number area 81 is used in the random selection of the current game prize status, the random number stored in the second random number area 82 is used in the random selection of the prize status in the game following the current game, the random number stored in the third random number area 83 is used in the random selection of the prize status of the subsequent game, and the random number stored in the fourth random number area 84 is used in the random selection of the prize status in the game after that. That is, random numbers to be used up through the next three games from the current game are stored. To return to the flowchart 400 of FIG. 7, in the all clear step 401 , the entire system is initialized and the random numbers stored in the random number store 80 are cleared. Following the all clear step 401 is the step 402 in which random numbers for four games (a total of four random numbers) are sampled and the sampled random numbers are stored in the first, second, third and fourth areas 81 - 84 in the random number store 80 . Following the step 402 is the game start step 404 , where the main unit 10 of the slot machine is placed in game start mode. In the step 406 , it is determined whether a token has been inserted. In the step 408 , which occurs after a token has been inserted, it is determined whether the start lever 5 or the spin switch 8 has been pulled. When the start lever 5 has been actuated, it is determined at the test step 410 whether any of the four random numbers in the random number store 80 correspond to a “Second Game Win” condition. When there is no “Second Game Win” condition, the game proceeds to the step 414 . When there is a “Second Game Win” condition, a demonstration flag is set up in the step 412 . Alternatively, a different type of demonstration could be made depending on whether a different combination of game results, including, for example, a “Big Jackpot” and a “Second Game Win”, or a “Small Jackpot” and a “Second Game Win”, or a “Second Game Win” and a “One Shy” condition (which will be described below), or some variation thereof, was present in one or more of the areas in the random number store 80 . For example, a state in which there is no “Big Jackpot” because the symbol on one of the reels 4 L, 4 C, 4 R (three reels in the present embodiment) does not match (here, the state of two matches is called “One Shy”). (If four or more reels were used and all but two reels matched, then the state could be called “Two Shy”, and so on, depending on the number of reels used. For example, the condition of having all but a predetermined number of reels, or dice, or other similar type of game feature, match or correspond is referred to herein as a pseudo specific game result condition.) Alternatively, a different type of demonstration could be made depending on whether a “One Shy”, “Two Shy”, “Big Jackpot”, “Little Jackpot”, “Second Game Win,” multiple “Free” or “Bonus” games, or some combination or variation thereof, was present in one or more of the areas in the random number store 80 . In the step 414 , a random number is taken from the first random number area 81 in the random number store 80 . The random number thus taken is used for random selection of the current game prize status, and the current game prize status is determined. In the step 416 , the random number stored in the second random number area 82 is then moved to the first random number area 81 , the random number stored in the third random number area 83 is moved to the second random number area 82 , and the random number stored in the fourth random number area 84 is moved to the third random number area 83 . In the step 418 , a new random number to be stored in the fourth random number area 84 is then sampled. In the step 420 , the new random number is stored in the fourth random number area 84 . In the step 422 , the system checks to see whether or not the demonstration flag is ON, i.e., is set. When the demonstration flag is not ON, the reels begin to rotate together as usual in the step 426 . When the demonstration flag is ON, the reels start rotating in a staggered manner (for example, the first reel 4 L is rotated, and a little while later the second and third reels 4 C, 4 R are rotated) in the step 424 . A demonstration may be made shortly after the reels begin to rotate. That is, a player may know there is no probability of a “Big Jackpot” or a “Second Game Win” when the reels start to rotate simultaneously, whereas a player may know that there is a probability of a “Big Jackpot” or a “Second Game Win” when the reels start rotating in a staggered manner, thereby giving the player greater hope. When all the reels are stopped, the demonstration flag is cleared in a clearing step 428 , and the game is over. The system subsequently returns to the game start step 404 at the start of the game, and the next game is begun. In the present embodiment, it is possible to determine the prize status, that is, the stopping position of all of the reels 4 L, 4 C, 4 R with one random number. However, the present invention is not limited to this embodiment, and a random number may be provided for each reel. To return to the description in FIG. 7, random numbers for four games (total of four random numbers) are sampled in the step 402 , the sampled random numbers are stored in the four random numbers areas 81 - 84 in the random number store 80 , and the slot machine is put in game start mode 404 . Whether or not a token has been inserted is then detected in the step 406 , and after a token has been inserted, whether or not the start lever 5 or the spin switch 8 has been pulled on is then detected in the step 408 . When the start lever 5 is on, the step 410 checks to see whether or not any of the four random numbers in the random number store 80 correspond to a “Second Game Win” state, that is, a prize allowing a second subsidiary game to be played. When there is no “Second Game Win” random number, the game proceeds to the step 414 , and when there is a “Second Game Win” random number, a demonstration flag is set up in the step 412 . In the step 414 , a random number is taken from the first random number area 81 in the random number store 80 , the random number thus taken is used for the random selection of the current game prize status, and the current game prize status is determined. The random number stored in the second random number area 82 of the random number store 80 is then moved to the first random number area 81 , the random number stored in the third random number area 83 is moved to the second random number area 82 , and the random number stored in the fourth random number area 84 is moved to the third random number area 83 in the step 416 . A new random number to be stored in the fourth random number area 84 of the random number store 80 is then sampled in the step 418 , and the new random number is then stored in the fourth random number area 84 in the step 420 . Here, the system checks to see whether or not the demonstration flag is ON, namely, is set in the step 422 . When the demonstration flag is not ON, the reels begin to rotate together as usual in the step 426 , and when the demonstration flag is ON, the reels start rotating while staggered (for example, reel 4 L is rotated, and a little while later reels 4 C and 4 R are rotated) in the step 424 . In the present embodiment, a demonstration is made a little after the reels begin to rotate. That is, the player knows there is no probability of a “Second Game Win” when the reels start to rotate simultaneously, whereas the knowledge that there is a probability of a “Second Game Win” when the reels start rotating while staggered gives the player greater hope. When all the reels are stopped, the demonstration flag is cleared in the step 428 , and a second game is played if there is a “Second Game Win,” and the game is over when the second game is over. The system subsequently returns to the step 404 , and the next game is begun. When there is no “Second Game Win” in the step 410 , the demonstration flag is not set and the system subsequently returns to the step 404 without playing a second game, and the next game is played. Thus, a player must enter one or more tokens to play the next game if there is no “Second Game Win” in the step 410 . However, if there is a “Second Game Win”, the game machine will recognize that fact and the player will not be required to enter more tokens to play another game after the system reaches the step 101 at the end of the first game. Thus, with reference to FIG. 3, when a “Second Game Win” result has been achieved, the game will proceed directly to step 104 without requiring a positive response in the test step 102 in which the system normally checks to see if a token has been entered before activating the first line. Optionally, a player could be required to enter additional tokens to activate additional lines in the “Free” or “Bonus” second game, or more than one line could be activated automatically, without the insertion of additional tokens, as part of the prize from the first game. In the present embodiment, random numbers for the current game through the next three games are previously sampled and are used to determine whether or not a demonstration is to be made in the current game, so there is a greater number of games with demonstrations, making it possible to provide effective demonstrations arousing the interest of the player. In the present embodiment, a demonstration is made on the possibility of a “Second Game Win” at the beginning of the first game, but the present invention is not limited to this. The results of the second game may be randomly selected at the first game stage, with a presentation made according to the results of the second game. In the present embodiment, a plurality of random numbers to be used in the next three games can be stored in the random number store 80 , but the present invention is not limited to this, and a plurality of random numbers to be used in more or less than the next three games can also be stored in the random number store 80 . Another alternative embodiment of a slot machine applying the present invention is described below. The appearance and basic operation of the slot machine in this alternative embodiment are similar to those of the embodiment described above, so FIGS. 1 through 6 are also applicable here and will not be described again. The method for randomly selecting the prize status and the method for determining whether or not a demonstration is to be made, which are features of the alternative embodiment, are described first. As described above, the prize status is randomly selected as result of a match between the random number values sampled at the start of the game and the groups of numerical values for awarding a prize which are stored in the prize table in the ROM 51 . FIG. 9 is a flow chart of the operations of the slot machine in the present embodiment. FIG. 10 illustrates the structure of the random number store in the present embodiment. FIG. 9 is a flowchart 500 illustrating operation of the slot machine in the additional alternative embodiment. The process begins with an all clear step 501 . Following the step 501 is a step 502 in which two types of random numbers are sampled for four games and are stored in the random number store. Following the step 502 is a game start step 504 in which the game is started. Following the step 504 is a test step 506 in which it is determined whether a token has been entered. If so, control passes to a test step 508 . Otherwise, the test step 506 is repeated until a token is entered. In the test step 508 , it is determined whether the start lever is ON. If so, control passes to a test step 510 . Otherwise, the test steps 506 , 508 are repeated until either a token is entered or the start lever 26 is ON. In the test step 510 , it is determined whether a “Second Game Win” condition occurs in the random number store. If so, control passes to a step 512 in which a demonstration flag is set. Otherwise, control passes from the step 510 to a step 514 . In the step 514 , a random number from a category A (described below) is sampled. Following the step 514 is a step 516 in which a random number from the first random number area of the random number store is extracted to determine the prize status for the current game. Following the step 516 is a step 518 in which there is a shift of the numbers in the random number store (as described below). Following the step 518 is a step 520 in which two types of random numbers are sampled for one game. Following the step 520 is a step 522 in which the two types of random numbers sampled in the step 520 are stored in the fourth random number storage area in the random number store. Following the step 522 is a test step 524 in which it is determined whether the demonstration flag is ON. If so, control passes to a step 526 in which a staggered reel start is made. Otherwise, control passes from the step 524 to a step 528 in which a normal reel start is made. Following the step 526 or the step 528 is a step 530 . In the step 530 , the demonstration flag is cleared when all reels stop. Following the step 530 is a game over step 532 . Following the game over step 532 , control returns to the game start step 504 . When, for example, the main power source switch of the slot machine is turned on, or when a clear switch not shown in the figures is switched ON, the entire system is initialized, the random numbers stored in the random number store 90 shown in FIG. 10 are cleared, and the demonstration flag described below is cleared in the step 501 . As shown in FIG. 10, the random number store 90 has four areas: a first random number area 91 , a second random number area 92 , a third random number area 93 , and a fourth random number area 94 , in each of which are provided two types of areas for first and second random numbers. The random number store 91 can thus store eight random numbers consisting of random numbers α1 and α2, random numbers β1 and β2, random numbers γ1 and γ2, and random numbers δ1 and δ2. Here, the random numbers stored in the random number store 90 are referred to as random numbers B. Either of the two types of random numbers (first and second random numbers) stored in the first random number area 91 is used in the random selection of the current game prize status, either of the two random numbers stored in the second random number area 92 is used in the random selection of the prize status in the game following the current game, either of the numbers stored in the third random number area 93 is used in the random selection of the prize status of the subsequent game, and either of the random numbers stored in the fourth random number area 94 is used in the random selection of the prize status in the game after that. That is, random numbers to be used up through the next three games from the current game are stored. In this embodiment, separate random numbers that are not stored in the random number store 90 are also provided. These random numbers are referred to as random numbers A. The random numbers A are random numbers obtained by the random generation of two types of numbers such as 0 and 1. The random number used in the current game is selected from between the two random numbers (first and second random numbers) stored in random number 1 of the random store 90 , depending on whether the random number A is 0 or 1. In the present embodiment, the prize status, that is, the position where the reels 4 L, 4 C, 4 R stop, can be determined with one random number. The present invention is not limited to this, however, and random numbers may be provided for each reel. To return to the description in FIG. 9, in the step 502 , random numbers for four games (total of eight random numbers) are sampled, the sampled random numbers are stored in the four random number areas 91 - 94 in the random number store 90 , and the slot machine is put in game start mode in the step 504 . Whether or not a token has been inserted is then detected in the step 506 , and after a token has been inserted, whether or not the start lever 5 or spin switch 8 has been pulled on is then detected in the step 508 . When the start lever 5 or spin switch 8 is on, the step 510 checks to see whether or not any of the eight random numbers in the random number store 90 correspond to a “Second Game Win” state, that is, a prize allowing a second subsidiary game to be played. When there is no “Second Game Win” random number, the game advances to the step 514 , and when there is a “Second Game Win” random number, a demonstration flag is set in the step 512 . In the step 514 , the random numbers A described above are sampled, and the random number used in the current game is determined from among the two types of random numbers (random numbers (α1 and α2) stored in the first random number area 91 of the random number store 90 based on the value of the random number A. The random number thus determined is taken from the random number store 90 and is used for the random selection of the prize status of the current game to determine the prize status of the current game in the step 516 . The two types of random numbers scored in the second random number area 92 of the random number store 90 are then moved to the first random number area 91 , the two types of random numbers stored in the third random number area 93 are moved to the second random number area 92 , and the two types of random numbers stored in the fourth random number area 94 are moved to the third random number area 93 , in the step 518 . Two new random numbers to be stored in the fourth random number area 94 of the random number store 90 are then sampled in the step 520 and stored in the fourth random number area 94 in the step 522 . Here, the system checks to see whether or not the demonstration flag is ON, namely, is set in the step 524 . When the demonstration flag is not ON, the reels begin to rotate together as usual in the step 528 , and when the demonstration flag is ON, the reels start rotating while staggered (for example, reel 4 L is rotated, and a little while later reels 4 C and 4 R are rotated) in the step 526 . In the present embodiment, a demonstration is made a little after the reels begin to rotate. That is, the player knows there is no probability of a “Second Game Win” when the reels start to rotate simultaneously, whereas the knowledge that there is a probability of a “Second Game Win” when the reels start rotating while staggered gives the player greater hope. However, whether or not the random number for the “Second Game Win” is actually used is randomly selected after the demonstration flag has been set, so the result sometimes ends up a “loss” despite the demonstration, contradicting the expectations of the player and arousing his or her ire. Thus, when all the reels have stopped, the demonstration flag is cleared in the step 530 , a second game is played when there is a “Second Game Win,” and the game is over upon the conclusion of the second game. The system subsequently returns to the step 504 , and the next game is begun. When there is no “Second Game Win” in the step 510 , the game is over, and the system then returns to the step 504 for the next game. In the present embodiment, random numbers for the current game through the next three games are previously sampled and are used to determine whether or not a demonstration is to be made in the current game, so there is a greater number of games with demonstrations, making it possible to provide effective demonstrations arousing the interest of the player. In the present embodiment, random numbers used in the current game are selected from two types of numbers (first and second random numbers), so a total of eight random numbers are used as a basis for determining whether or not a demonstration is to be made, thus increasing the number of games with demonstrations and making it possible to provide effective demonstrations arousing the interest of the player. In the present embodiment, a demonstration is made on the possibility of a “Second Game Win” at the beginning of the first game, but the present invention is not limited to this. The results of the second game may be randomly selected at the first game stage, with a presentation made according to the results of the second game. In the present embodiment, a plurality of random numbers to be used in the next three games can be stored in the random number store 90 , but the present invention is not limited to this, and a plurality of random numbers to be used in the next several games can also be stored in the random number store 90 . In the present embodiment, random numbers A allowing two types of random numbers to be taken are provided, and two different types of random numbers used per game are stored in the random number store 90 , but the present invention is not limited to this; random numbers A allowing several random numbers to be taken may be provided, and the random numbers used per game may be stored in groups of several in the random number store 90 . The demonstration means in the present embodiments involved staggering the reels, but the invention is not limited to this and may also be constructed so as to appeal to the overall senses of the player by flashing the display lamps of the prize line or the sound from a sound generator. The embodiments described above were related to mechanical types of slot machines in which reels are rotated but the present invention is not limited to this mechanical type of slot machine and can also be applied to video game machines. The present invention is not limited to slot machines and can be applied to poker game machines or any other type of game machine allowing the game results to be randomly selected. When the present invention is applied to video game machines, the display image can be warped, for example, as a demonstration. As described above, the game machine described herein arouses the interest of the play to play more games because demonstrations are made when a “Second Game Win” has been obtained by random selection to determine the game prize status. In another embodiment, the game machine described herein randomly selects game results from the current game to the next several games, and determines whether or not a demonstration is to be made in the current game, so there are more games with presentations, allowing effective demonstrations to be made to arouse the interest of the player in playing more games. In an alternative embodiment, the game machine described herein selects the game result state to be used in the current game from among various types states, so there are more games with presentations, allowing effective demonstrations to be made to arouse the interest of the player in playing more games. While the invention has been disclosed in connection with the preferred embodiments shown and described in detail, various modifications and improvements thereon will become readily apparent to those skilled in the art. Accordingly, the spirit and scope of the present invention is to be limited only by the following claims.

In a game machine, game result conditions may be randomly selected for a predetermined number of games among a plurality of given game result conditions and a demonstration may be made to provide a player of the game with a feeling of higher probability of winning a prize in the game when the randomly selected game result conditions include a given specific game result condition. The demonstration may be made by a variety of possible techniques, including using a flashing light or changing the volume or tone of a sound. Random numbers may be sampled in advance for random selection of game result conditions for the current game and for one or more games that will follow the current game, i.e., ranging several games down from the current game. These random numbers may be used to determine whether or not a demonstration should be made in the current game. As a result, more games will have demonstrations than in existing games, in which only the current games status can be considered, and more effective demonstrations may be made to enhance a player's interest in playing more games. The present invention is a game machine that randomly selects the game result conditions of a first game by lottery from among a plurality of conditions, and that determines the game results on the basis of the randomly selected results, wherein the player is alerted by a presentation to the fact that a “Second Game Win” condition exists among randomly selected conditions.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for converting β-keto esters to ketones, and to novel ketones produced therefrom. Specifically, this invention relates to the method of decarbalkoxylating alkylated β-keto esters using a phase-transfer agent to yield ketones. The present invention also relates to novel methylene-linked pyrethroid insecticides produced by the method of the invention. 2. Description of the Prior Art Ketones are very valuable commercial compounds. One synthetic route for the preparation of ketones is via the conversion of alkylated β-keto esters. Classical synthetic approaches to such conversions are known. For example, it is known that acid-catalyzed decarboxylation in an aqueous or nonaqueous medium, following alkaline hydrolysis of β-keto esters provides simple access to ketones. However, because this conversion method can be unpredictable, with little or no yield, its use as a commercial synthetic process is not desirable. Several previous and more recent approaches to ketone synthesis through conversion of β-keto esters employ a retro Claisen-type reaction. Such syntheses require a nonaqueous medium and/or high reaction temperatures, thereby presenting a potential environmental hazard and necessitating much time and expense. Also, the retro Claisen-type reactions are undesirable since they may require another method to complete the synthesis. For example, when a crown ester is used to convert several β-sp 2 carbon ester compounds to carboxylates in an alkaline medium, acidification and/or thermolysis are required to complete ketone synthesis. Consequently, there exists a need for a method of converting alkylated β-keto esters to ketones which is more predictable, cost effective, and environmentally safer than prior art processes. In addition, there is a need for a facile approach to the conversion of β-keto esters to ketones which produces a yield which is practical for commercial application. SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved process for the decarbalkoxylation of alkylated β-keto esters to produce high yields of ketones. Another object of the present invention is to provide a novel process for the conversion of the β-keto esters to ketones in a facile, economical and commercially acceptable manner. Still another object of the present invention is to provide novel methylene-linked pyrethroid insecticidal compounds. In accordance with the method of the invention, decarbalkoxylation of β-keto esters is accomplished by heating the ester in the presence of dilute aqueous alkali and an effective amount of a phase-transfer agent for a period of time sufficient to decarbalkoxylate the ester. An advantageous feature of the invention method is that the process is not specific, but may be used to prepare a limitless quantity of keto products. Examples of novel methylene-linked pyrethroid insecticides produced by the method of the invention include compounds represented by the general formula ##STR1## wherein R is 2,2-dimethyl-3-(2-methylpropenyl)cyclopropyl; 2,2-dimethyl-3-(cyclopentanylidenemethyl)cyclopropyl; or 1-(4-chlorophenyl)-2-methyl propyl. Other novel methylene-linked pyrethroid insecticides produced by the invention method include compounds represented by the general formula ##STR2## wherein R is 2,2-dimethyl-3-(cyclopentanylidenemethyl)cyclopropyl; or 2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropyl. DETAILED DESCRIPTION OF THE INVENTION For purposes of this invention, the term "phase-transfer agent" is defined herein to mean a reagent that allows the transport of a reactive species between two immiscible phrases. In the preferred embodiment, the method comprises (1) forming an emulsion of a β-keto ester with dilute aqueous alkali, i.e. potassium hydroxide or sodium hydroxide, which contains an effective amount, preferably from about 0.1 to 10%, of a phase-transfer agent such as hexadecycltrimethylammonium bromide, cetyltrimethylammonium bromide, benzylcetyldimethylammonium chloride, or the like; (2) heating said emulsion at about 60° C. to 90° C., perferably under nitrogen, with stirring and sonication for about a period of time sufficient to decarbalkoxylate the ester, preferably from about 30 to 90 minutes; (3) neutralizing the reaction mixture with dilute acid, i.e. dilute sulfuric or hydrochloric acid; and (4) thereafter, recovering the resulting ketone. To aid emulsion formation, the β-keto ester may optionally be dissolved in an organic solvent such as toluene, hexane or heptane, prior to mixing with the dilute alkali solution containing the phase-transfer agent. Preferred reaction times and temperatures for individual esters may vary depending upon the molecular weight of the esters. It appears that the lower the molecular weight of the ester, the lower the temperature and the shorter the reaction time required to complete decarbalkoxylation. Isolation of the ketone is accomplished by extraction of the crude reacton mixture with an appropriate organic solvent, e.g. ethyl ether, ethyl acetate or the like. The crude product is sequentially washed with dilute base and saturated salt solutions. Thereafter, the crude product is dried over a suitable drying agent, filtered and the solvent removed. Final purification may be accomplished by dry-packed silica gel, column chromatography using an appropriate organic solvent. It is within the scope of this invention to prepare the esters using any suitable esterification procedure. In general, the β-keto esters useful in the invention method may be synthesized from their acid chloride using the well-known Meldrum's acid (2,2-dimethyl-1,3-dioxane-4,6-dione). The resulting trione is thereafter converted to the desired β-keto ester with the appropriate alcohol. Alternatively, the esters may be prepared by condensing the precursor ketone, which is obtained using the cadmium methyl alkylation of the corresponding acid chloride with diethyl carbonate. Alkylation of the formed β-keto ester may be accomplished using conventional alkylation methodology. For example, the esters may be alkylated with the appropriate alkyl halide in the presence of a suitable base, or with sodium hydride in an appropriate solvent, i.e. THF or benzene. Products prepared from the ketones produced from the method of the invention have a variety of commercial uses including, but not limited to, perfumed, flavor additives, antioxidants, preservatives, inhibitors, intermediates for resins, plastics, adhesives, pharmaceuticals and dyes. Some ketone products such as methylene-linked pyrethroids have demonstrated insecticidal activity. When used, the ketones produced by the method of the invention may be used in solid or liquid form. As will be obvious to one skilled in the arts, the ketones may be used in various compositions of ketones and a carrier. Depending upon the intended use, such compositions may additionally contain conventional additives such as emulsifying agents, wetting agents, binding agents, odorants, stabilizers and the like. The following examples are intended to further illustrate the invention as herein disclosed and not to limit the scope of the invention as defined by the claims. EXAMPLE I Five alkylated β-keto esters having the general formula ##STR3## wherein R 1 is methyl and R 2 is propyl, butyl, hexyl, phenylmethyl or phenylethyl, were converted to the corresponding ketones using the phase-transfer decarbalkoxylation method of the invention. The phase-transfer decarbalkoxylation procedure was as follows: 100 mg of the candidate β-keto ester was added to 5 ml of 10% aqueous potassium hydroxide that contained 0.1% of hexadecyltrimethylammonium bromide. If needed, the ester was dissolved in toluene (100 mg/0.25 ml) to aid micelle formation. The mixture was vigorously stirred under nitrogen and sonication, and heated at 80° C. for 45 minutes. Thereafter, the reaction mixture was acidified with 1N sulfuric acid and the mixture extracted with 25 ml of ethyl ether. The organic phase was dried with MgSO 4 , filtered and concentrated to a light oil. The isolate was purified by dry column chromatography on silica gel using hexane to develop the column. The isolate was quantified and the structure was confirmed by capillary GC/CI-MS (Extrel Corp., Model EL-400-2 fitted with and EL-1000 data system). Yields of the corresponding ketones are recorded in Table I. In all examples, the yield of the ketones exceeded 75%. EXAMPLE II In this example, five alkylated β-keto esters, having the general formula ##STR4## wherein R is 2,2-dimethyl-3-(2-methylpropenyl)cyclopropyl; 2,2-dimethyl 3-(cyclopentanylidenemethyl)cyclopropyl; or 1-(4-chlorophenyl)-2-methyl propyl; and the general formula ##STR5## wherein R is 2,2-dimethyl-3-(cyclopentanylidenemethyl)cyclopropyl; or 2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropyl, were converted to the corresponding methylene-linked pyrethroids using the method of the invention. TABLE I______________________________________Phase Transfer Catalyzed Decarbalkoxylationof β-Keto Esters (R.sup.1 COCHR.sup.2 CO.sub.2 C.sub.2 H.sub.5)β-Keto EsterR.sup.1 R.sup.2 Product Yield (%).sup.a,b______________________________________Me CH.sub.3 CH.sub.2 CH.sub.2 2-hexanone 75.sup.cMe CH.sub.3 (CH.sub.2).sub.3 2-heptanone 85.sup.dMe CH.sub.3 (CH.sub.2).sub.5 2-nonanone 95.sup.dMe C.sub.6 H.sub.5 CH.sub.2 1-phenyl-2-butanone 96.sup.dMe C.sub.6 H.sub.5 CH.sub.2 CH.sub.2 1-phenyl-2-pentanone 90.sup.d______________________________________ .sup.a Quadrex 007 Methylsilicone, 15 M × 0.25 mm; flow = 1.7 cm sec.sup.-1. .sup.b Yields of isolated 2heptanone and 1phenyl-2-butanone were comparable to those suggested by GLC analyses. .sup.c Temp. program: 35° C. for 1 min., 60° C./min. to 80° C., isothermal at 80° C. .sup.d Temp. program: 35° C., 60° C./min. to 80° C., then 60° C./min. to 170° C. The decarbalkoxylation procedure was as follows: A stock reagent was prepared containing 10% of hexadecyltrimethylammonium bromide dissolved in a solution of 10% aqueous potassium hydroxide. 1 g of the candidate β-keto ester was dissolved in a minimum amount of heptane and was added to 50 ml of the reagent. The reaction mixture was sonicated at 80° C. and monitored by analytical TLC. The reaction was usually completed at 90 minutes. The cooled reaction mixture was acidified with dilute hydrochloric acid and then extracted twice with 25 ml of ethyl acetate. The combined organic extracts were washed with 5% sodium bicarbonate and a saturated sodium chloride solution. After drying with MgSO 4 , filtration and removal of the solvent, the isolate was purified by dry-packed silica gel column chromatography using ethyl acetate (3-10%) in hexane to develop the column. The resulting ketones, each a mixture of two optical isomers, were obtained as a colorless oil or semi-solid at -4° C. Yields are recorded in Table II. The novel methylene-linked pyrethroids were all produced in good yield. In all examples the yield exceeded 73%. Accordingly, the method of the invention is useful to convert structurally complicated β-keto esters to ketones in commercially acceptable yields. The novel methylene-linked pyrethroids of Example II were found to exhibit insecticidal activity useful against various agricultural pests. To show the effectiveness of the novel pyrethroids, the insecticidal activities of the compounds of Example II were compared to the activity of phenothrin. Additionally, the activity of the alkylated β-keto ester precursors of the compounds of Example II were compared to that of phenothrin. TABLE II__________________________________________________________________________Phase-Transfer Catalyzed Decarbalkoxylation of Alkylatedβ-Keto Esters (R.sup.1 COCHR.sup.2 CO.sub.2 C.sub.2 H.sub.5)__________________________________________________________________________ β-Keto Ester (R.sup.1 COCHR.sup.2 CO.sub.2 C.sub.2 H.sub.5)Compound R.sup.1 R.sup.2__________________________________________________________________________ ##STR6## ##STR7##B ##STR8## ##STR9##C ##STR10## ##STR11##D ##STR12## ##STR13##E ##STR14## ##STR15##__________________________________________________________________________Compound Product Yield (%)__________________________________________________________________________ ##STR16## 87B ##STR17## 84C ##STR18## 86D ##STR19## 74E ##STR20## 85__________________________________________________________________________ Activity was determined on the basis of results obtained from the foregoing insecticide tests: INSECTICIDE TEST METHODS Topical Application Test Yellow Mealworm, Tenetrio molitor Linnaeus (YMW), Method of Treatment Formulations were made to contain 100 μg of the candidate compound per 1 μl of acetone/DMSO (1:1 volume ratio) solvent. Topical application was performed with 1 μl calibrated glass micropipet fitted with a rubber bulb. One μl of the formulation was applied on the ventral of the last 3 abdominal segments of each of 5 adults, male and female. The insects were placed in a 9 cm petri dish. Method of Recording Results Mortality and morbidity were recorded after 72 hours. Mode of action may be by contact. Feed Additive Test Fall Armyworm, Spodoptera frugiperda (J. E. Smith) (FAW), Method of Treatment Formulations were prepared to contain 100 μg of the candidate compound per 1 μl of acetone/DMSO (1:1 volume:ratio) solvent. 100 μl of the formulation was incorporated into 100 g of standard hot diet. Treated diets were poured into 1 oz. jelly cups at the rate of 10 g/cup and allowed to cool to room temperature. Method of Recording Results First and fifth instars were weighed and mortality was noted after 7 days. Third instars were allowed to go to adult where mortality, egg production and hatch were recorded. Mode of action may be by stomach poison, contact or vapor. Test concentrations and results are set forth in Table III. Phenothrin used in the above tests was sold under the tradename "Multicide Sumithrin" by McLauglin, Gromley, King Co. of Minneapolis, MN. As shown in Table III, the newly prepared pyrethroids of Example II showed varied activity against both insect species, YMW and FAW, with activity appearing to be least in the early larval stages. With the exception of compounds A and D, none of the ketones expressed an appreciable antifeedent behavior in larvae FAW. Compound A exhibited some mortality activity in FAW larvae but only compounds D and E had significant mortality. Notedly, none of the β-keto esters caused mortality or significant antifeedent activity in the larvae FAW. Looking at the YMW, all the ketones and their alkylated β-keto esters caused 100% mortality in the adult YMW. Only compound D caused 100 percent mortality in the YMW pupae. The remaining compounds were for the most part inactive against the YMW pupae, with only compounds A, B and D 1 showing a minimal activity. It is understood that modifications and variations may be made to the foregoing disclosure without departing from the spirit and scope of the invention. TABLE III______________________________________Insect Bioassay of Methylene-Linked Pyrethroids.sup.aMortality/Activity at 100 PPM.sup.b Fall Army Yellow Meal Worm (FAW) Worm (YMW)Compound Larvae.sup.c (%).sup.d Pupae Adult______________________________________A.sup.1.spsp.e 0(71) 0 100B.sup.1.spsp.e 0(70) 0 100C.sup.1.spsp.e 0(70) 0 100D.sup.1.spsp.e 0(80) 20 80E.sup.1.spsp.e 0(75) 0 100A 30(49) .sup. 20(.6).sup.f 100B 0(90) 20 100C 0(84) 0 100D 80(68) 100 100E 50(20) 0 100PHENOTHRIN 100(00) 100 100______________________________________ .sup.a Only trans geometric isomers of the compounds listed were used in the above test. .sup.b Topical application. .sup.c 1st Instar, diet application. .sup.d Relative antifeedant activity (% of normal growth). .sup.e A.sup.1, B.sup.1, C.sup.1, D.sup.1, and E.sup.1 represents alkylated β-keto esters precursors ketones A, B, C, D and E. .sup.f JH rating.

An improved method for the decarbalkoxylation of alkylated β-keto esters to obtain high yields of ketones. In accordane with the method, decarbalkoxylation of alkylated β-keto esters is accomplished by heating the esters in the presence of dilute aqueous alkali and an effective amount of a phase-transfer agent. The method produces commercially practical yields of ketone in a manner which is facile, economical and environmentally safe. Novel methylene-linked pyrethroid ketones produced from the improved method exhibit insecticidal activity against various agricultural pests.

CROSS REFERENCE TO RELATED APPLICATIONS The present application is related to, and claims priority to, Korean patent application KR 10-2007-0099473, filed on Oct. 2, 2007, the entire contents of which being incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device, computer program product and method of inputting a character in a touch screen device, and more specifically, to a method of inputting a character, in which a touch area is partitioned into a plurality of array positions, and one or more characters are assigned to each of the partitioned array positions, so that if one of the partitioned array positions is touched, the characters assigned to the touched array positions are enlarged and rearranged on the touch screen to allow a user to select an input character. 2. Description of the Related Art As portable electronic devices are miniaturized in size and in pursuit of a simple design recently, the portable electronic devices are gradually provided with a touch screen in place of mechanical key buttons that require a certain fixed space. Positions and settings of input buttons of an input device using a touch screen may be freely set or modified. Accordingly, recently manufactured portable electronic devices receive most of inputs through a touch pad, except only a minimum button inputs. Inputting characters is not an exception, and input of characters is also accomplished by touching the touch screen. When characters are inputted through a conventional touch screen, all characters are arranged on the touch screen, and a character touched by a user is inputted among the arranged characters. However, the prior art described above has following problems. That is, since the characters are many in number, and thus the width of the touch screen occupied by a character is narrow if all the characters are arranged on the touch screen, there is a problem in that readability of the characters is lowered and it becomes also difficult to arrange the characters. Furthermore, since a touch area occupied by a character is narrow according to the prior art, when a user who desires to input the character inputs the character, the user may touch adjacent other characters together and generate an input error, or may suffer from incorrect touches in using the touch screen. SUMMARY OF THE INVENTION The present invention is conceived to solve the aforementioned problems in the prior art. An object of the present invention is to provide a touch screen device, a computer program product and a method of inputting a character therein, in which input of characters is accomplished in multiple steps making use of versatility of the touch screen. Another object of the present invention is to provide a touch screen device, a computer program product and a method of inputting a character therein, in which representative characters are arranged on the touch screen, and when one of the representative characters is selected, characters subordinated to the selected character are displayed to receive a character. According to an aspect of the present invention for achieving the objects, there is provided a device, computer program product and method of inputting a character on a touch screen receiving a character by sensing a touch of a touch panel. The method comprises the steps of: partitioning a touch area of the touch panel into a plurality of array positions and assigning one or more characters to each of the partitioned array positions; sensing an expansion event of selecting one among the array positions; dividing the touch area into a plurality of selection positions and assigning the characters assigned to the array position selected by the expansion event to the respective selection positions; sensing a selection event of selecting one among the selection positions; and recognizing the character assigned to the selection position selected by the selection event as an input character. At this time, the expansion event may be generated by a touch input of the user, and the selection event is generated by a release of the touch. Also, the expansion event and the selection event may be generated by a touch input of the user. In addition, if the selection event is generated on the touch panel out of the selection positions, the selection event may be recognized as a command for canceling input of a character. At this time, the array positions may be formed by dividing the touch area into a matrix form of n×m. In addition, if two or more characters are assigned to the selection positions, the selection positions may be formed to expand in directions including one or more of up, down, left and right sides from a position where the expansion event is generated. At this time, n and m are 3, respectively; and in the array positions (AP), three or less characters may be assigned to AP(1, 1), four or less characters may be assigned to AP(1, 2), three or less characters may be assigned to AP(1, 3), four or less characters may be assigned to AP(2, 1), five or less characters may be assigned to AP(2, 2), four or less characters may be assigned to AP(2, 3), three or less characters may be assigned to AP(3, 1), four or less characters may be assigned to AP(3, 2), and three or less characters may be assigned to AP(3, 3). In addition, the selection positions may be formed at the position of AP(1, 1) and to expand to the down and right sides therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the down, left and right sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the down and left sides therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up, down and right sides therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, down, left and right sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up, down and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up and right sides therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up and left sides therefrom if the expansion event is generated at AP(3, 3). The input character is a Korean letter, and Korean consonants and vowels may be sequentially assigned to the array positions. Here, and may be assigned to AP(1, 1); and may be assigned to AP(1, 2), and may be assigned to AP(1, 3); and may be assigned to AP(2, 1); and may be assigned to AP(2, 2); and may be assigned to AP(2, 3); and may be assigned to AP(3, 1); and may be assigned to AP(3, 2); and and may be assigned to AP(3, 3). In the meantime, n and m are 2, respectively; and in the array positions (AP), three or less characters may be assigned to AP(1, 1), three or less characters may be assigned to AP(1, 2), three or less characters may be assigned to AP(2, 1), and three or less characters may be assigned to AP(2, 2) At this time, the input character is a numeral, and Arabic numerals may be sequentially assigned to the array positions. Then, in the array positions (AP), 1, 2 and 3 may be assigned to AP(1, 1); 4, 5 and 6 may be assigned to AP(1, 2); 7, 8 and 9 may be assigned to AP(2, 1); and 0 may be assigned to AP(2, 2). In the meantime, if two or more characters are assigned to the selection position, the selection position may be formed to expand in directions including one or more of up, down and left sides from a position where the expansion event is generated. Here, n and m are 3, respectively; and in the array positions (AP), two or less characters may be assigned to AP(1, 1), three or less characters may be assigned to AP(1, 2), three or less characters may be assigned to AP(1, 3), three or less characters may be assigned to AP(2, 1), four or less characters may be assigned to AP(2, 2), four or less characters may be assigned to AP(2, 3), two or less characters may be assigned to AP(3, 1), three or less characters may be assigned to AP(3, 2), and three or less characters may be assigned to AP(3, 3). Then, the selection positions may be formed at the position of AP(1, 1) and to expand to the down side therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the left and down sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the left and down sides therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up and down sides therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, down and left sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up, down and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up side therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up and left sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up and left sides therefrom if the expansion event is generated at AP(3, 3). In addition, the input character is an English letter, and English letters may be assigned to the array positions in sequence of a QWERTY array. Then, in the array positions, Q and W may be assigned to AP(1, 1); E, R and T may be assigned to AP(1, 2); Y, U and I may be assigned to APP(1, 3); O, P and A may be assigned to AP(2, 1); S, D, F and (may be assigned to AP(2, 2); U, J, K and L may be assigned to AP(2, 3); Z and X may be assigned to AP(3, 1); C, V and B may be assigned to AP(3, 2); and N and M may be assigned to AP(3, 3). Further, in the array positions, and may be assigned to AP(1, 1); and may be assigned to AP(1, 2); and may be assigned to AP(1, 3); and may be assigned to AP(2, 1); and may be assigned to AP(2, 2); and may be assigned to AP(2, 3); and may be assigned to AP(3, 1); and may be assigned to AP(3, 2); and and may be assigned to AP(3, 3). In the meantime if two or more characters are assigned to the selection position, the selection position may be formed to expand in directions including one or more of up, left and right sides from a position where the expansion event is generated. Then, n and m are 3, respectively; and in the array positions 70 , two or less letters may be assigned to AP(1, 1), three or less letters may be assigned to AP(1, 2), two or less letters may be assigned to AP(1, 3), three or less letters may be assigned to AP(2, 1), four or less letters may be assigned to AP(2, 2), three or less letters may be assigned to AP(2, 3), three or less letters may be assigned to AP(3, 1), four or less letters may be assigned to AP(3, 2), and two or less letters may be assigned to AP(3, 3). Then, the selection positions may be formed at the position of AP(1, 1) and to expand to the right side therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the left and right sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the left side therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up and right sides therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up and right sides therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the left side therefrom if the expansion event is generated at AP(3, 3). At this time, in the array positions, Q and W may be assigned to AP(1, 1); E, R and T may be assigned to AP(1, 2); Y and U may be assigned to AP(1, 3); I, O and P may be assigned to AP(2, 1); A, S, D and F may be assigned to AP(2, 2); G, H and J may be assigned to AP(2, 3); K, L and Z may be assigned to AP(3, 1); X, C, V and B may be assigned to AP(3, 2); and N and M may be assigned to AP(3, 3). Alternatively, in the array positions, and may be assigned to AP(1, 1); and may be assigned to AP(1, 2); and may be assigned to AP(1, 3); and may be assigned to AP(2, 1); and may be assigned to AP(2, 2); and may be assigned to AP(2, 3); and may be assigned to AP(3, 1); and may be assigned to AP(3, 2); and and may be assigned to AP(3, 3). In addition, n and m are 3, respectively; three or less letters may be assigned to AP(1, 1), four or less letters may be assigned to AP(1, 2), three or less letters may be assigned to AP(1, 3), two or less letters may be assigned to AP(2, 1), four or less letters may be assigned to AP(2, 2), three or less letters may be assigned to AP(2, 3), two or less letters may be assigned to AP(3, 1), three or less letters may be assigned to AP(3, 2), and two or less letters may be assigned to AP(3, 3). Then, the selection positions 90 may be formed at the position of AP(1, 1) and to expand to the up and right sides therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the up and left sides therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up side therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up side therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up and left sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up side therefrom if the expansion event is generated at AP(3, 3). At this time, in the array positions, Q, W and E may be assigned to AP(1, 1); R, T, Y and U may be assigned to AP(1, 2); I, O and P may be assigned to AP(1, 3); A and S may be assigned to AP(2, 1), D, F, G and H may be assigned to AP(2, 2); J, K and L may be assigned to AP(2, 3); Z and X may be assigned to AP(3, 1); C, V and B may be assigned to AP(3, 2); and N and M may be assigned to AP(3, 3). In addition, n and m are respectively 3, and one character may be assigned to AP(1, 1), two or less letters may be assigned to AP(1, 2), two or less letters may be assigned to AP(1, 3), two or less letters may be assigned to AP(2, 1), three or less letters may be assigned to AP(2, 2), two or less letters may be assigned to AP(2, 3), two or less letters may be assigned to AP(3, 1), four or less letters may be assigned to AP(3, 2), and three or less letters may be assigned to AP(3, 3). Then, the selection position may be the position of AP(1, 1) if the expansion event is generated at AP(1, 1); and the selection positions may be formed at the position of AP(1, 2) and to expand to the left side therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the left side therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the left side therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up and left sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the left side therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up side therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up, left, and right sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up and left sides therefrom if the expansion event is generated at AP(3, 3). At this time, in the array positions, an “Add a stroke” button may be assigned to AP(1, 1); and may be assigned to AP(1, 2); and may be assigned to AP(1, 3); and may be assigned to AP(2, 1); and may be assigned to AP(2, 2); and may be assigned to AP(2, 3); and may be assigned to AP(3, 1); and may be assigned to AP(3, 2); and and may be assigned to AP(3, 3). In the meantime, the present invention provides a method of inputting a character on a touch screen receiving a character by sensing a touch of a touch panel. The method comprises the steps of: partitioning a touch area of the touch screen into a plurality of array positions and assigning one or more characters to each of the partitioned array positions; enlarging and rearranging the characters, which are assigned to one of the partitioned array positions selected by a user, on the touch screen; and recognizing one of the rearranged characters reselected by the user as an input character. In addition, the assigned characters may be arranged in the partitioned array position so that one of the characters is arranged at a center and the other characters are arranged at one or more positions of up, down, left and right sides of the character arranged at the center. At this time, the character arranged at the center may be set to be larger than the other characters within the same partitioned array position in common. Further, the expansion may be performed from the character arranged at the center in directions where the other characters are arranged. Furthermore, the rearrangement of characters may be performed so that one of the characters is arranged in each of the expanding directions. In addition, the present invention provides a touch screen device, which comprises: a touch panel controller for sensing a touch and a touch release of a touch panel; a display controller for outputting an image of a character corresponding to the touch or touch release on a screen; and a control unit for receiving a result of the sensing from the touch panel controller and controlling the display controller to output an image of a character corresponding to the result of the sensing, and receiving the corresponding character depending on the result of the sensing, wherein the control unit partitions a touch area of the touch screen into a plurality of array positions to assign one or more characters to each of the partitioned array positions, rearranges the characters, which are assigned to one of the partitioned array positions selected by a user, on the touch screen, and recognizes one of the rearranged characters reselected by the user as an input character. According to the touch screen device and the method of inputting a character therein according to the present invention described above, the following effects can be expected. That is, since only representative characters are initially arranged and displayed on the touch screen, a touch area assigned to a character is widened, and thus it is advantageous in that readability of characters of a user is enhanced. Furthermore, since a touch area assigned to a character is widened as described above, the present invention has an advantage in that an input error occurring by touching a character together with adjacent characters can be prevented when a user inputs the character. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of a touch screen device according to a specific embodiment of the present invention; FIG. 2 is a flowchart illustrating a method of inputting a character in the touch screen device according to the specific embodiment of the present invention; FIGS. 3 a to 3 d are exemplary views showing operating states of a first application example of the present invention; FIGS. 4 a to 4 b are exemplary views showing operating states of a second application example of the present invention; FIGS. 5 a to 5 d are exemplary views showing operating states of a third application example of the present invention; FIG. 6 is an exemplary view showing an operating state of a fourth application example of the present invention; FIG. 7 is an exemplary view showing an operating state of a fifth application example of the present invention; FIG. 8 is an exemplary view showing an operating state of a sixth application example of the present invention; FIGS. 9 a to 9 b are exemplary views showing operating states of a seventh application example of the present invention; and FIG. 10 is an exemplary view showing an operating state of an eighth application example of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment of the touch screen device and the method of inputting a character therein according to the present invention described above will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of a touch screen device according to a specific embodiment of the present invention. As shown in the figure, the touch screen device of the present invention is provided with a touch panel 10 for sensing a touch of a user. The touch panel 10 may be a variety of known touch panels of a piezoelectric type, capacitive type, or the like. Then, the touch panel 10 is connected with a touch panel controller 20 for sensing a touch on the touch panel 10 and the position of the touch and controlling the operation of the touch panel 10 . That is, if there is a touch input of a user on the touch panel 10 , the touch panel 10 converts the touch into an electrical signal and transfers the electrical signal to the touch panel controller 20 , and the touch panel controller 20 recognizes the touch input (including touch release) and calculates an input position. In the meantime, the touch panel is combined with a display screen 30 . The display screen is a general display device, such as a liquid crystal display (LCD), a plasma display panel (PDP), a cathode ray tube (CRT), or the like, which is a part for displaying an image to be outputted to a user. In addition, in the specific embodiment of the present invention, the display screen 30 , which is a part for displaying a touch position to the user, displays a character to be inputted when the touch panel is touched and displays an area where the character is assigned. Meanwhile, the display screen 30 is connected to a display controller 40 for controlling the display screen 30 . The display controller 40 is a part for changing an image to be displayed on the display screen 30 depending on a command of a control unit 50 and an input mode that will be described below. The control unit 50 for controlling the touch panel controller 20 and the display controller 40 is connected to the touch panel controller 20 and the display controller 40 . That is, the control unit 50 initially arranges and displays characters to be inputted on the display and then changes and displays arrangement of the characters in response to a user's input. In addition, the control unit 50 serves to receive the fact and the position of the touch input (including a touch release input) of the user from the touch panel controller 20 , search for a corresponding command, and change the display and input mode according to the corresponding command. At this time, a specific example describing how the control unit 50 operates in response to a user's input will be described below. In the meantime, the control unit 50 is connected with a storage unit 60 for storing information on how the control unit 50 controls the touch panel controller 20 and the display controller 40 depending on a user's touch input. Hereinafter, a specific control method of the control unit 50 for controlling the touch panel controller 20 and the display controller 40 will be described. Here, the control of the touch panel 10 and the display controller 40 is controlling the touch panel 10 and the display screen 30 through the touch panel controller 20 and the display controller 40 . Before describing the control method of the control unit 50 , some terminologies are defined for convenience of explanation, and the method will be described using some defined terminologies. Examples of referenced items may be found in the figures. First, an array position 70 is a partitioned area to which a character is assigned in a character input mode. Then, an expansion event is an input command for selecting one of array positions 70 . In addition, a selection position 90 is an area on the touch screen, where a character assigned to the selected array position 70 is rearranged when the expansion event is inputted. Then, a selection event is an event of selecting a character by selecting one of selection positions 90 . At this time, the character selected and inputted by the selection event is referred to as an input character. First, in the character input mode, the control unit 50 divides the touch screen into a plurality of array positions 70 . Then, one or more characters are assigned to each of the array positions 70 . At this time, the array positions 70 may be arranged in a rectangular form of n×m or in a square form of n×n. Then, if an expansion event is sensed from one of the array positions 70 , the control unit 50 rearranges the characters assigned to the sensed array position 70 , from which the expansion event is sensed, on the selection positions 90 . At this time, the expansion event is generated when the user touches a corresponding area. In the meantime, upon observing a response state of the controller according to the user's touch input, if the touch input is normally made within an area, the character within the area is recognized to be inputted without a problem. However, if two adjacent array positions are touched (when a border line is touched), first, 1) it may be determined that any touch is not made. Alternatively, 2) the touched areas are compared, and an array position which is comparatively broader among the two touched array positions may be determined as being selected. Alternatively, 3) a message for requesting to confirm which of the two array positions is the selected array position may be displayed to the user. Then, the selection positions 90 are set as many as the characters assigned to the array position 70 selected by the expansion event. The selection positions 90 may be set randomly or with a specific rule. Specific examples of the rule for setting the selection positions 90 will be described. The selection positions 90 may be formed to expand in directions including one or more of the up, down, left, and right sides from the point where the expansion event is generated; in directions including one or more of the up, down, and left sides from the point where the expansion event is generated; or in directions including one or more of the up, left, and right sides from the point where the expansion event is generated. Alternatively, the selection positions 90 may be formed to expand in directions including one or more of the up and left sides from the point where the expansion event is generated. If the selection positions 90 are formed to expand in four directions of up, down, left, and right sides, there is an advantage in that the number of the selection positions 90 that can be arranged on the touch screen is increased. Then, if the selection positions 90 are formed to expand in two directions of up and left sides, there is an advantage in that the screen can be prevented from being shielded with the user's hand when the user touches the touch screen. It is apparent that this is for general right-handed users, and a direction to the right can be set instead of a direction to the left for left-handed users. However, in this case, there is a disadvantage in that the number of selection positions 90 that can be arranged is small. Accordingly, a method into which the aforementioned methods are combined may be used in consideration of the number of characters to be arranged, and the second and third methods are examples of the combined method. Then, if a selection event is generated from the touch panel 10 , the control unit 50 recognizes a character assigned to the selection position 90 where the selection event is generated as the input character and then processes the input. At this time, if the selection event is generated from an area out of the selection positions 90 , the control unit 50 recognizes the selection event as a command for canceling the input character and then cancels the input of the character. In the meantime, if the input of the character is completed or cancelled, the control unit 50 restores the touch screen to a waiting state of an initial character input mode. Here, the input event may be generated by a touch release of the user or by touching the touch panel 10 by the user. That is, the selection positions 90 are set by an expansion event generated by touching the array position 70 , and the selection event may be generated by releasing the touch after selecting one of the selection positions 90 by dragging the touch while the touch is maintained. Alternatively, the expansion event and the selection event may be generated by separate touches. In the meantime, the control unit 50 may be connected to the storage unit 60 for storing information on settings of the array positions 70 and the selection positions 90 and information on settings of expansion events and selection events. The storage unit 60 stores forms of the array positions 70 differently set by the type of characters, such as English characters, Korean characters, numerals, and the like, as well as assigned characters, display information, and the like. Then, the storage unit stores an execution command corresponding to an expansion event for each of the array positions 70 when the expansion event is inputted. In addition, the storage unit also stores information on the form of each selection position 90 and characters arranged on the selection position. The storage unit also stores an execution command corresponding to a selection event for each of the selection position 90 . Hereinafter, the operation of the touch screen device according to the present invention will be described in detail through the method of inputting a character. FIG. 2 is a flowchart illustrating a method of inputting a character in the touch screen device according to the specific embodiment of the present invention. As shown in the figure, the method of inputting a character according to a specific embodiment of the present invention first determines whether an expansion event is sensed by a user. The expansion event is generated by a user's touch as described above (step S 10 ). The present invention, which relates to a method of inputting a character on a touch screen, will be described basically assuming that the touch screen device is in a character input mode. At this time, the touch screen is in a character input waiting state, and the array positions 70 are set as described above. Next, the control unit 50 searches for execution information corresponding to the position where the expansion event is generated (step S 120 ). At this time, the execution information can be searched from the information stored in the storage unit 60 . The execution information includes all of setting information on the manner of arranging the selection positions 90 in correspondence with the expansion event and on characters to be assigned to each of the arranged selection positions 90 together with the manner of assigning the characters to the selection positions. Then, the touch panel 10 and the display are set again based on the searched execution information (step S 130 ). That is, the selection positions 90 are arranged on the touch screen, and corresponding characters are assigned. Thereafter, it is determined whether a selection event is inputted by the user (step S 140 ). The selection event may be a touch or a touch release of the user as described above. After the selection event is sensed, the input position of the selection event is determined (step S 150 ). At this time, it is determined whether the input position of the selection event is within the selection positions 90 . If the input position of the selection event is within the selection positions 90 , a character set to the position where the selection event is generated is recognized as an input character, and the character is inputted (step S 170 ). If the input character is inputted or the selection event is generated out of the selection positions 90 , display settings of the touch panel 10 and the display screen 30 are restored to the settings of the character input waiting state (step S 180 ). At this time, the restoration means returning the settings to the settings of the initial character input waiting state. Thereafter, it is determined whether the character input mode is released, and execution of the present invention is terminated if the character input mode is released, whereas the touch screen device waits for input of a new character if the character input mode is continued (step S 190 ). Here, the method of combining inputted characters and constructing a syllable, a word, or the like is the same as a known prior art. Hereinafter, examples of the present invention, in which the specific embodiment of the present invention is practically employed and operates on a touch screen, will be described in detail with reference to the accompanying drawings. FIGS. 3 a to 3 d are exemplary views showing operating states of a first application example of the present invention. FIG. 3 a is a view showing the array positions 70 of the first application example. Korean letters are inputted in the first application example, and the array positions 70 are formed in a 3×3 matrix. At this time, the array positions (AP) 70 are respectively expressed as AP (1, 1) to AP (3, 3) for convenience of explanation. In the array positions 70 , three or less letters are assigned to AP(1, 1), four or less letters are assigned to AP(1, 2), three or less letters are assigned to AP(1, 3), four or less letters are assigned to AP(2, 1), five or less letters are assigned to AP(2, 2), four or less letters are assigned to AP(2, 3), three or less letters are assigned to AP(3, 1), four or less letters are assigned to AP(3, 2), and three or less letters are assigned to AP(3, 3). Then, Korean consonants and vowels are sequentially assigned to the array positions 70 . In other embodiments, other non-English symbols (e.g., Arabic, Chinese, Kangi, etc.) may be used. Thus, a person conversant with these non-English alphabets may practice the invention in the alphabet of their choice. Upon describing an example of arranging the Korean letters, as shown in FIG. 3 a , and are assigned to AP(1, 1); and are assigned to AP(1, 2); and are assigned to AP(1, 3); and are assigned to AP(2, 1); and are assigned to AP(2, 2); and are assigned to AP(2, 3); and are assigned to AP(3, 1); and are assigned to AP(3, 2); and and are assigned to AP(3, 3). At this time, although there are a variety of methods for displaying the letters, a representative letter among the assigned letters may be displayed in a large size, and the other letters may be arranged in a small size, as shown in the figure. At this time, if one of the array positions 70 is touched, selection positions 90 are set in response to the touch. The selection positions 90 are formed to expand in the directions including one or more of the up, down, left and right sides from the position where the expansion event is generated. Upon describing the expansions one by one, the selection positions 90 are formed at the position of AP(1, 1) and to expand to the down and right sides therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the down, left and right sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the down and left sides therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up, down and right sides therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, down, left and right sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up, down and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up and right sides therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up and left sides therefrom if the expansion event is generated at AP(3, 3). For example, if is touched as shown in FIG. 3 b , five selection positions 90 are set by expanding to the up, down, left, and right sides from as shown in FIG. 3 c , and and are respectively assigned to the selection positions. Thereafter, while being touched on , a stylus pen 80 is dragged to the position of . Then, if the stylus pen 80 releases the touch at the position of (a selection event is generated), is inputted as shown in FIG. 3 d . A finger or another device may be used in place of the stylus pen 80 . At this time, it is apparent that if the stylus pen 80 releases the touch out of the selection positions 90 (at the shaded area), the input of the letter is cancelled, and the touch screen device is transferred to the initial waiting mode ( FIG. 3 a ). In addition, the selection event may be generated by separate touches as described above. FIGS. 4 a to 4 b are exemplary views showing operating states of a second application example of the present invention. FIG. 4 a is a view showing the array positions 70 of the second application example. Numerals are inputted in the second application example, and the array positions 70 are formed in a 2×2 matrix. In the array positions 70 , three or less characters are assigned to AP(1, 1), three or less characters are assigned to AP(1, 2), three or less characters are assigned to AP(2, 1), and three or less characters are assigned to AP(2, 2). Then, as shown in FIG. 4 a , in the array positions 70 , numerals 1 , 2 , and 3 are assigned to AP(1, 1); numerals 4 , 5 , and 6 are assigned to AP(1, 2); numerals 7 , 8 , and 9 are assigned to AP(2, 1); and numeral 0 is assigned to AP(2, 2). At this time, the arrangement of the selection positions 90 is set in the same manner as the first application example. Then, if “11” is selected among the array positions 70 , selection positions are set as shown in FIG. 4 b. Then, a selection event is generated, and a character is inputted in the same manner as described above. FIGS. 5 a to 5 d are exemplary views showing operating states of a third application example of the present invention. FIG. 5 a is a view showing the array positions 70 of the third application example. English letters are inputted in the third application example, and the array positions 70 are formed in a 3×3 matrix. At this time, in the array positions 70 , two or less letters are assigned to AP(l, 1), three or less letters are assigned to AP(1, 2), three or less letters are assigned to AP(T, 3), three or less letters are assigned to AP(2, 1), four or less letters are assigned to AP(2, 2), four or less letters are assigned to AP(2, 3), two or less letters are assigned to AP(3, 1), three or less letters are assigned to AP(3, 2), and two or less letters are assigned to AP(3, 3). English letters are arranged in the sequence of the QWERTY array, wherein the sequence of the QWERTY array means the sequence of letters arranged on a keyboard. In the array positions 70 , Q and W are assigned to AP(1, 1); E, R and T are assigned to AP(1, 2); Y, U and I are assigned to AP(1, 3); 0, P and A are assigned to AP(2, 1); S, D, F and G are assigned to AP(2, 2); H, J, K and L are assigned to AP(2, 3); Z and X are assigned to AP(3, 1); C, V and B are assigned to AP(3, 2); and N and M are assigned to AP(3, 3). At this time, if one of the array positions 70 is touched, selection positions 90 are set in response to the touch. The selection positions 90 are formed to expand in one or more directions including the up, down and left sides from the position where the expansion event is generated. Upon describing the expansions one by one, the selection positions 90 are formed at the position of AP(1, 1) and to expand to the down side therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the left and down sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the left and down sides therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up and down sides therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, down and left sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up, down and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up side therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up and left sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the left side therefrom if the expansion event is generated at AP(3, 3). For example, if “E” is touched as shown in FIG. 5 b , four selection positions 90 are set by expanding to the left, right and down sides from “E” as shown in FIG. 5 e , and E, R, Y and T are respectively assigned to the selection positions. Thereafter, while being touched on “E”, the stylus pen 80 is dragged to the position of “T”. Then, if the stylus pen 80 releases the touch at the position of “T” (a selection event is generated), “T” is inputted as shown in FIG. 5 d. At this time, it is apparent that if the stylus pen 80 releases the touch out of the selection positions 90 , the input of the letter is cancelled, and the touch screen device is transferred to the initial waiting mode, which is the same as described above. In addition, the selection event may be generated by separate touches as described above. FIG. 6 is an exemplary view showing an operating state of a fourth application example of the present invention. Korean letters are inputted in the fourth application example in the same manner as the third application example, and Korean consonants and vowels are sequentially assigned. In the array positions 70 , and are assigned to AP(1, 1); and are assigned to AP(1, 2); and are assigned to AP(1, 3); and are assigned to AP(2, 1); and are assigned to AP(2, 2); and are assigned to AP(2, 3); and are assigned to AP(3, 1); and are assigned to AP(3, 2); and and are assigned to AP(3, 3). FIG. 7 is an exemplary view showing an operating state of a fifth application example of the present invention. At this time, the fifth application example is formed in a 3×3 matrix, and in the array positions 70 , two or less letters are assigned to AP(1, 1), three or less letters are assigned to AP(1, 2), two or less letters are assigned to AP(1, 3), three or less letters are assigned to AP(2, 1), four or less letters are assigned to AP(2, 2), three or less letters are assigned to AP(2, 3), three or less letters are assigned to AP(3, 1), four or less letters are assigned to AP(3, 2), and two or less letters are assigned to AP(3, 3). Upon describing further specifically, in the array positions 70 , Q and W are assigned to AP(1, 1); E, R and T are assigned to AP(1, 2); Y and U are assigned to AP(1, 3); I, O and P are assigned to AP(2, 1); A, S, D and F are assigned to AP(2, 2); G, H and J are assigned to AP(2, 3); K, L and Z are assigned to AP(3, 1); X, C, V and B are assigned to AP(3, 2); and N and M are assigned to AP(3, 3). At this time, although it is not shown in the figure, the selection positions 90 are formed to expand in one or more directions including the up, left and right sides from the position where the expansion event is generated. Upon describing further specifically, the selection positions 90 are formed at the position of AP(1, 1) and to expand to the right side therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the left and right sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the left side therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up and right sides therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up and right sides therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the left side therefrom if the expansion event is generated at AP(3, 3). In the meantime, FIG. 8 is an exemplary view showing an operating state of a sixth application example of the present invention, wherein the sixth application example is an example where Korean letters are assigned in the same manner as the fifth application example. In the sixth application examples in the array positions 70 , and are assigned to AP(1, 1); and are assigned to AP(1, 2); and are assigned to AP(1, 3); and are assigned to AP(2, 1); and are assigned to AP(2, 2); and are assigned to AP(2, 3); and are assigned to AP(3, 1); and are assigned to AP(3, 2); and and are assigned to AP(3, 3). FIGS. 9 a to 9 b are exemplary views showing operating states of a seventh application example of the present invention. English letters are arranged in the seventh application example, and the array positions 70 are formed in a 3×3 matrix, in which three or less letters are assigned to AP(1, 1), four or less letters are assigned to AP(1, 2), three or less letters are assigned to AP(1, 3), two or less letters are assigned to AP(2, 1), four or less letters are assigned to AP(2, 2), three or less letters are assigned to AP(2, 3), two or less letters are assigned to AP(3, 1), three or less letters are assigned to AP(3, 2), and two or less letters are assigned to AP(3, 3). In the array positions 70 , Q, W and E are assigned to AP(1, 1); R, T, Y and U are assigned to AP(1, 2); I, O and P are assigned to AP(1, 3); A and S are assigned to AP(2, 1); D, F, G and H are assigned to AP(2, 2); J, K and L are assigned to AP(2, 3); Z and X are assigned to AP(3, 1); C, V and B are assigned to AP(3, 2); and N and M are assigned to AP(3, 3). In the meantime, in the seventh application example, the selection positions 90 are formed at the position of AP(1, 1) and to expand to the up and right sides therefrom if the expansion event is generated at AP(1, 1); at the position of AP(1, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the up and left sides therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the up side therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up, left and right sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the up and left sides therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up side therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up and left sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up side therefrom if the expansion event is generated at AP(3, 3). For example, if “R” is touched among the array positions 70 as shown in FIG. 9 b , selection positions 90 are set to the up, left and right sides from “R”, and T, Y and U are respectively assigned to the up, left and right sides. Then, the selection event and the method of inputting a character are the same as described above. FIG. 10 is an exemplary view showing an operating state of an eighth application example of the present invention. In the eighth application example, the array positions 70 are formed in a 3×3 matrix, in which one character is assigned to AP(1, 1), two or less letters are assigned to AP(1, 2), two or less letters are assigned to AP(1, 3), two or less letters are assigned to AP(2, 1), three or less letters are assigned to AP(2, 2), two or less letters are assigned to AP(2, 3), two or less letters are assigned to AP(3, 1), four or less letters are assigned to AP(3, 2), and three or less letters are assigned to AP(3, 3). At this time, the input characters are Korean letters, and Korean consonants and vowels are sequentially assigned to the array positions 70 . Then, in the array positions 70 , an “Add a stroke” button is assigned to AP(1, 1); and are assigned to AP(1, 2); and are assigned to AP(1, 3); and are assigned to AP(2, 1); and are assigned to AP(2, 2); and are assigned to AP(2, 3); and are assigned to AP(3, 1); and are assigned to AP(3, 2); and and are assigned to AP(3, 3). The “add a stroke” button allows a user to add a stroke symbol as a displayed symbol. Other symbols may be used as an added symbol. Although the selection positions 90 are intended to expand to the up and left sides from the selected array position 70 in the eighth application example, four letters are assigned to AP(3, 2) in order to set an array for convenience of users, and selection positions 90 are set to the up, left and right sides only from the selected array position. It is apparent that the position of the selection position 90 to which four letters are assigned may be differently set. Accordingly, in the eighth application example, the selection position 90 is the position of AP(1, 1) if the expansion event is generated at AP(1, 1); and the selection positions 90 are formed at the position of AP(1, 2) and to expand to the left side therefrom if the expansion event is generated at AP(1, 2); at the position of AP(1, 3) and to the left side therefrom if the expansion event is generated at AP(1, 3); at the position of AP(2, 1) and to the left side therefrom if the expansion event is generated at AP(2, 1); at the position of AP(2, 2) and to the up and left sides therefrom if the expansion event is generated at AP(2, 2); at the position of AP(2, 3) and to the left side therefrom if the expansion event is generated at AP(2, 3); at the position of AP(3, 1) and to the up side therefrom if the expansion event is generated at AP(3, 1); at the position of AP(3, 2) and to the up, left, and right sides therefrom if the expansion event is generated at AP(3, 2); and at the position of AP(3, 3) and to the up and left sides therefrom if the expansion event is generated at AP(3, 3). In the specific embodiment of the invention described above, it has been described that expansion directions and the number of the selection positions are predetermined, and accordingly, the number of characters assigned to each of the array positions and the forms of the array positions are determined. However, according to another aspect of the present invention, the touch screen is partitioned into array positions of a matrix form, and one or more characters are assigned to each of the partitioned array positions. At this time, the characters are arranged so that relatively large-sized one of the characters is arranged at the center of the partitioned array position, and the other characters are arranged at one or more positions of the up, down, left and right sides centering on the large-sized character. In addition, expansion of the array position depends on the directions and the number of the assigned characters. That is, the expansion is performed from the position of the character arranged at the center toward the directions where the other characters are arranged, and the other characters is respectively assigned to the expanding selection positions and displayed on the selection position. At this time, it is apparent that the characters may be displayed in the same size. The touch panel of the present invention may be included in a wireless communication device (e.g., cell phone) or a personal data assistant (PDA) configured to communicate with another device via a network (e.g., a CDMA, Bluetooth or other wireless network). Various embodiments described herein may be implemented in a computer-readable medium using, for example, computer software, hardware, or some combination thereof. For a hardware implementation, the embodiments described herein may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a selective combination thereof. For a software implementation, the embodiments described herein may be implemented with separate software modules, such as procedures and functions, each of which perform one or more of the functions and operations described herein. The software codes can be implemented with a software application written in any suitable programming language and may be stored in memory, and executed by a controller or processor. The scope of the present invention is not limited to the embodiments described above but is defined by the appended claims. It will be apparent that those skilled in the art can make various modifications and changes thereto within the scope of the invention defined by the claims.

A device, computer program product and method of inputting a character in a touch screen device, in which a touch area is partitioned into a plurality of array positions, and one or more letters are assigned to each of the partitioned array positions. The method comprises the steps of: partitioning a touch area of the touch panel into a plurality of array positions and assigning one or more characters to each of the partitioned array positions; sensing an expansion event of selecting one among the array positions; dividing the touch area into a plurality of selection positions and assigning the characters assigned to the array position selected by the expansion event to the respective selection positions; sensing a selection event of selecting one among the selection positions; and recognizing the character assigned to the selection position selected by the selection event as an input character.

CROSS-REFERENCE TO RELATED APPLICATION This application is a division of application Ser. No. 09/378,124, filed Aug. 19, 1999, now U.S. Pat. No. 6,325,146 which claims the benefit of the filing date of provisional application serial No. 60/127,106, filed Mar. 31, 1999, such prior applications being incorporated by reference herein in their entirety. BACKGROUND OF THE INVENTION The present invention relates generally to operations performed in conjunction with subterranean wells and, in an embodiment described herein, more particularly provides a method of performing a downhole test of a subterranean formation. In a typical well test known as a drill stem test, a drill string is installed in a well with specialized drill stem test equipment interconnected in the drill string. The purpose of the test is generally to evaluate the potential profitability of completing a particular formation or other zone of interest, and thereby producing hydrocarbons from the formation. Of course, if it is desired to inject fluid into the formation, then the purpose of the test may be to determine the feasibility of such an injection program. In a typical drill stem test, fluids are flowed from the formation, through the drill string and to the earth's surface at various flow rates, and the drill string may be closed to flow therethrough at least once during the test. Unfortunately, the formation fluids have in the past been exhausted to the atmosphere during the test, or otherwise discharged to the environment, many times with hydrocarbons therein being burned off in a flare. It will be readily appreciated that this procedure presents not only environmental hazards, but safety hazards as well. Therefore, it would be very advantageous to provide a method whereby a formation may be tested, without discharging hydrocarbons or other formation fluids to the environment, or without flowing the formation fluids to the earth's surface. It would also be advantageous to provide apparatus for use in performing the method. SUMMARY OF THE INVENTION In carrying out the principles of the present invention, in accordance with an embodiment thereof, a method is provided in which a formation test is performed downhole, without flowing formation fluids to the earth's surface, or without discharging the fluids to the environment. Also provided are associated apparatus for use in performing the method. In one aspect of the present invention, a method includes steps wherein a formation is perforated, and fluids from the formation are flowed into a large surge chamber associated with a tubular string installed in the well. Of course, if the well is uncased, the perforation step is unnecessary. The surge chamber may be a portion of the tubular string. Valves are provided above and below the surge chamber, so that the formation fluids may be flowed, pumped or reinjected back into the formation after the test, or the fluids may be circulated (or reverse circulated) to the earth's surface for analysis. In another aspect of the present invention, a method includes steps to wherein fluids from a first formation are flowed into a tubular string installed in the well, and the fluids are then disposed of by injecting the fluids into a second formation. The disposal operation may be performed by alternately applying fluid pressure to the tubular string, by operating a pump in the tubular string, by taking advantage of a pressure differential between the formations, or by other means. A sample of the formation fluid may conveniently be brought to the earth's surface for analysis by utilizing apparatus provided by the present invention. In yet another aspect of the present invention, a method includes steps wherein fluids are flowed from a first formation and into a second formation utilizing an apparatus which may be conveyed into a tubular string positioned in the well. The apparatus may include a pump which may be driven by fluid flow through a fluid conduit, such as coiled tubing, attached to the apparatus. The apparatus may also include sample chambers therein for retrieving samples of the formation fluids. In each of the above methods, the apparatus associated therewith may include various fluid property sensors, fluid and solid identification sensors, flow control devices, instrumentation, data communication devices, samplers, etc., for use in analyzing the test progress, for analyzing the fluids and/or solid matter flowed from the formation, for retrieval of stored test data, for real time analysis and/or transmission of test data, etc. These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view of a well wherein a first method and apparatus embodying principles of the present invention are utilized for testing a formation; FIG. 2 is a schematic cross-sectional view of a well wherein a second method and apparatus embodying principles of the present invention are utilized for testing a formation; FIG. 3 is an enlarged scale schematic cross-sectional view of a device which may be used in the second method; FIG. 4 is a schematic cross-sectional view of a well wherein a third method and apparatus embodying principles of the present invention are utilized for testing a formation; FIG. 5 is an enlarged scale schematic cross-sectional view of a device which may be used in the third method; and FIG. 6 is a schematic cross-sectional view of a well wherein a fourth method and apparatus embodying principles of the present invention are utilized for testing a formation. DETAILED DESCRIPTION Representatively illustrated in FIG. 1 is a method 10 which embodies principles of the present invention. In the following description of the method 10 and other apparatus and methods described herein, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. Additionally, it is to be understood that the various embodiments of the present invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., without departing from the principles of the present invention. In the method 10 as representatively depicted in FIG. 1, a wellbore 12 has been drilled intersecting a formation or zone of interest 14 , and the wellbore has been lined with casing 16 and cement 17 . In the further description of the method 10 below, the wellbore 12 is referred to as the, interior of the casing 16 , but it is to be clearly understood that, with appropriate modification in a manner well understood by those skilled in the art, a method incorporating principles of the present invention may be performed in an uncased wellbore, and in that situation the wellbore would more appropriately refer to the uncased bore of the well. A tubular string 18 is conveyed into the wellbore 12 . The string 18 may consist mainly of drill pipe, or other segmented tubular members, or it may be substantially unsegmented, such as coiled tubing. At a lower end of the string 18 , a formation test assembly 20 is interconnected in the string. The assembly 20 includes the following items of equipment, in order beginning at the bottom of the assembly as representatively depicted in FIG. 1 : one or more generally tubular waste chambers 22 , an optional packer 24 , one or more perforating guns 26 , a firing head 28 , a circulating valve 30 , a packer 32 , a circulating valve 34 , a gauge carrier 36 with associated gauges 38 , a tester valve 40 , a tubular surge chamber 42 , a tester valve 44 , a data access sub 46 , a safety circulation valve 48 , and a slip joint 50 . Note that several of these listed items of equipment are optional in the method 10 , other items of equipment may be substituted for some of the listed items of equipment, and/or additional items of equipment may be utilized in the method and, therefore, the assembly depicted in FIG. 1 is to be considered as merely representative of an assembly which may be used in a method incorporating principles of the present invention, and not as an assembly which must necessarily be used in such method. The waste chambers 22 may be comprised of hollow tubular members, for example, empty perforating guns (i.e., with no perforating charges therein). The waste chambers 22 are used in the method 10 to collect waste from the wellbore 12 immediately after the perforating gun 26 is fired to perforate the formation 14 . This waste may include perforating debris, wellbore fluids, formation fluids, formation sand, etc. Additionally, the pressure reduction in the wellbore 12 created when the waste chambers 22 are opened to the wellbore may assist in cleaning perforations 52 created by the perforating gun 26 , thereby enhancing fluid flow from the formation 14 during the test. In general, the waste chambers 22 are utilized to collect waste from the wellbore 12 and perforations 52 prior to performing the actual formation test, but other purposes may be served by the waste chambers, such as drawing unwanted fluids out of the formation 14 , for example, fluids injected therein during the well drilling process. The packer 24 may be used to straddle the formation 14 if another formation therebelow is open to the wellbore 12 , a large rathole exists below the formation, or if it is desired to inject fluids flowed from the formation 14 into another fluid disposal formation as described in more detail below. The packer 24 is shown unset in FIG. 1 as an indication that its use is not necessary in the method 10 , but it could be included in the string 18 , if desired. The perforating gun 26 and associated firing head 28 may be any conventional means of forming an opening from the wellbore 12 to the formation 14 . Of course, as described above, the well may be uncased at its intersection with the formation 14 . Alternatively, the formation 14 may be perforated before the assembly 20 is conveyed into the well, the formation may be perforated by conveying a perforating gun through the assembly after the assembly is conveyed into the well, etc. The circulating valve 30 is used to selectively permit fluid communication between the wellbore 12 and the interior of the assembly 20 below the packer 32 , so that formation fluids may be drawn into the interior of the assembly above the packer. The circulating valve 30 may include openable ports 54 for permitting fluid flow therethrough after the perforating gun 26 has fired and waste has been collected in the waste chambers 22 . The packer 32 isolates an annulus 56 above the packer formed between the string 18 and the wellbore 12 from the wellbore below the packer. As depicted in FIG. 1, the packer 32 is set in the wellbore 12 when the perforating gun 26 is positioned opposite the formation 14 , and before the gun is fired. The circulating valve 34 may be interconnected above the packer 32 to permit circulation of fluid through the assembly 20 above the packer, if desired. The gauge carrier 36 and associated gauges 38 are used to collect test data, such as pressure, temperature, etc., during the formation test. It is to be clearly understood that the gauge carrier 36 is merely representative of a variety of means which may be used to collect such data For example, pressure and/or temperature gauges may be included in the surge chamber 42 and/or the waste chambers 22 . Additionally, note that the gauges 38 may acquire data from the interior of the assembly 20 and/or from the annulus 56 above and/or below the packer 32 . Preferably, one or more of the gauges 38 , or otherwise positioned gauges, records fluid pressure and temperature in the annulus 56 below the packer 32 , and between the packers 24 , 32 if the packer 24 is used, substantially continuously during the formation test. The tester valve 40 selectively permits fluid flow axially therethrough and/or laterally through a sidewall thereof. For example, the tester valve 40 may be an Omni™ valve, available from Halliburton Energy Services, Inc., in which case the valve may include a sliding sleeve valve 58 and closeable circulating ports 60 . The valve 58 selectively permits and prevents fluid flow axially through the assembly 20 , and the ports 60 selectively permit and prevent fluid communication between the interior of the surge chamber 42 and the annulus 56 . Other valves, and other types of valves, may be used in place of the representatively illustrated valve 40 , without departing from the principles of the present invention. The surge chamber 42 comprises one or more generally hollow tubular members, and may consist mainly of sections of drill pipe, or other conventional tubular goods, or may be purpose-built for use in the method 10 . It is contemplated that the interior of the surge chamber 42 may have a relatively large volume, such as approximately 20 barrels, so that, during the formation test, a substantial volume of fluid may be flowed from the formation 14 into the chamber, a sufficiently low initial drawdown pressure may be achieved during the test, etc. When conveyed into the well, the interior of the surge chamber 42 may be at atmospheric pressure, or it may be at another pressure, if desired. One or more sensors, such as sensor 62 , may be included with the chamber 42 , in order to acquire data, such as fluid property data (e.g., pressure, temperature, resistivity, viscosity, density, flow rate, etc.) and/or fluid identification data (e.g., by using nuclear magnetic resonance sensors available from Numar, Inc.). The sensor 62 may be in data communication with the data access sub 46 , or another remote location, by any data transmission means, for example, a line 64 extending external or internal relative to the assembly 20 , acoustic data transmission, electromagnetic data transmission, optical data transmission, etc. The valve 44 may be similar to the valve 40 described above, or it may be another type of valve. As representatively depicted in FIG. 1, the valve 44 includes a ball valve 66 and closeable circulating ports 68 . The ball valve 66 selectively permits and prevents fluid flow axially through the assembly 20 , and the ports 68 selectively permit and prevent fluid communication between the interior of the assembly 20 above the surge chamber 42 and the annulus 56 . Other valves, and other types of valves, may be used in place of the representatively illustrated valve 44 , without departing from the principles of the present invention. The data access sub 46 is representatively depicted as being of the type wherein such access is provided by conveying a wireline tool 70 therein in order to acquire the data transmitted from the sensor 62 . For example, the data access sub 46 may be a conventional wet connect sub. Such data access may be utilized to retrieve stored data and/or to provide real time access to data during the formation test. Note that a variety of other means may be utilized for accessing data acquired downhole in the method 10 , for example, the data may be transmitted directly to a remote location, other types of tools and data access subs may be utilized, etc. The safety circulation valve 48 may be similar to the valves 40 , 44 described above in that it may selectively permit and prevent fluid flow axially therethrough and through a sidewall thereof. However, preferably the valve 48 is of the type which is used only when a well control emergency occurs. In that instance, a ball valve 72 thereof (which is shown in its typical open position in FIG. 1) would be closed to prevent any possibility of formation fluids flowing further to the earth's surface, and circulation ports 74 would be opened to permit kill weight fluid to be circulated through the string 18 . The slip joint 50 is utilized in the method 10 to aid in positioning the assembly 20 in the well. For example, if the string 18 is to be landed in a subsea wellhead, the slip joint 50 may be useful in spacing out the assembly 20 relative to the formation 14 prior to setting the packer 32 . In the method 10 , the perforating guns 26 are positioned opposite the formation 14 and the packer 32 is set. If it is desired to isolate the formation 14 from the wellbore 12 below the formation, the optional packer 24 may be included in the string 18 and set so that the packers 32 , 24 straddle the formation. The formation 14 is perforated by firing the gun 26 , and the waste chambers 22 are immediately and automatically opened to the wellbore 12 upon such gun firing. For example, the waste chambers 22 may be in fluid communication with the interior of the perforating gun 26 , so that when the gun is fired, flow paths are provided by the detonated perforating charges through the gun sidewall. Of course, other means of providing such fluid communication may be provided, such as by a pressure operated device, a detonation operated device, etc., without departing from the principles of the present invention. At this point, the ports 54 may or may not be open, as desired, but preferably the ports are open when the gun 26 is fired. If not previously opened, the ports 54 are opened after the gun 26 is fired. This permits flow of fluids from the formation 14 into the interior of the assembly 20 above the packer 32 . When it is desired to perform the formation test, the tester valve 40 is opened by opening the valve 58 , thereby permitting the formation fluids to flow into the surge chamber 42 and achieving a drawdown on the formation 14 . The gauges 38 and sensor 62 acquire data indicative of the test, which, as described above, may be retrieved later or evaluated simultaneously with performance of the test. One or more conventional fluid samplers 76 may be positioned within, or otherwise in communication with, the chamber 42 for collection of one or more samples of the formation fluid. One or more of the fluid samplers 76 may also be positioned within, or otherwise in communication with, the waste chambers 22 . After the test, the valve 66 is opened and the ports 60 are opened, and the formation fluids in the surge chamber 42 are reverse circulated out of the chamber. Other circulation paths, such as the circulating valve 34 , may also be used. Alternatively, fluid pressure may be applied to the string 18 at the earth's surface before unsetting the packer 32 , and with valves 58 , 66 open, to flow the formation fluids back into the formation 14 . As another alternative, the assembly 20 may be repositioned in the well, so that the packers 24 , 32 straddle another formation intersected by the well, and the formation fluids may be flowed into this other formation. Thus, it is not necessary in the method 10 for formation fluids to be conveyed to the earth's surface unless desired, such as in the sampler 76 , or by reverse circulating the formation fluids to the earth's surface. Referring additionally now to FIG. 2, another method 80 embodying principles of the present invention is representatively depicted. In the method 80 , formation fluids are transferred from a formation 82 from which they originate, into another formation 84 for disposal, without it being necessary to flow the fluids to the earth's surface during a formation test, although the fluids may be conveyed to the earth's surface if desired. As depicted in FIG. 2, the disposal formation 84 is located uphole from the tested formation 82 , but it is to be clearly understood that these relative positionings could be reversed with appropriate changes to the apparatus and method described below, without departing from the principles of the present invention. A formation test assembly 86 is conveyed into the well interconnected in a tubular string 87 at a lower end thereof. The assembly 86 includes the following, listed beginning at the bottom of the assembly: the waste chambers 22 , the packer 24 , the gun 26 , the firing head 28 , the circulating valve 30 , the packer 32 , the circulating valve 34 , the gauge carrier 36 , a variable or fixed choke 88 , a check valve 90 , the tester valve 40 , a packer 92 , an optional pump 94 , a disposal sub 96 , a packer 98 , a circulating valve 100 , the data access sub 46 , and the tester valve 44 . Note that several of these listed items of equipment are optional in the method 80 , other items of equipment may be substituted for some of the listed items of equipment, and/or additional items of equipment may be utilized in the method and, therefore, the assembly 86 depicted in FIG. 2 is to be considered as merely representative of an assembly which may be used in a method incorporating principles of the present invention, and not as an assembly which must necessarily be used in such method. For example, the valve 40 , check valve 90 and choke 88 are shown as examples of flow control devices which may be installed in the assembly 86 between the formations 82 , 84 , and other flow control devices, or other types of flow control devices, may be utilized in the method 80 , in keeping with the principles of the present invention. As another example, the pump 94 may be used, if desired, to pump fluid from the test formation 82 , through the assembly 86 and into the disposal formation 84 , but use of the pump 94 is not necessary in the method 80 . Additionally, many of the items of equipment in the assembly 86 are shown as being the same as respective items of equipment used in the method 10 described above, but this is not necessarily the case. When the assembly 86 is conveyed into the well, the disposal formation 84 may have already been perforated, or the formation may be perforated by providing one or more additional perforating guns in the assembly, if desired. For example, additional perforating guns could be provided below the waste chambers 22 in the assembly 86 . The assembly 86 is positioned in the well with the gun 26 opposite the test formation 82 , the packers 24 , 32 , 92 , 98 are set, the circulating valve 30 is opened, if desired, if not already open, and the gun 26 is fired to perforate the formation. At this point, with the test formation 82 perforated, waste is immediately received into the waste chambers 22 as described above for the method 10 . The circulating valve 30 is opened, if not done previously, and the test formation is thereby placed in fluid communication with the interior of the assembly 86 . Preferably, when the assembly 86 is positioned in the well as shown in FIG. 2, a relatively low density fluid (liquid, gas (including air, at atmospheric or greater or lower pressure) and/or combinations of liquids and gases, etc.) is contained in the string 87 above the upper valve 44 . This creates a low hydrostatic pressure in the string 87 relative to fluid pressure in the test formation 82 , which pressure differential is used to draw fluids from the test formation into the assembly 86 as described more fully below. Note that the fluid preferably has a density which will create a pressure differential from the formation 82 to the interior of the assembly at the ports 54 when the valves 58 , 66 are open. However, it is to be clearly understood that other methods and means of drawing formation fluids into the assembly 86 may be utilized, without departing from the principles of the present invention. For example, the low density fluid could be circulated into the string 87 after positioning it in the well by opening the ports 68 , nitrogen could be used to displace fluid out of the string, a pump 94 could be used to pump fluid from the test formation 82 into the string, a difference in formation pressure between the two formations 82 , 84 could be used to induce flow from the higher pressure formation to the lower pressure formation, etc. After perforating the test formation 82 , fluids are flowed into the assembly 86 via the circulation valve 30 as described above, by opening the valves 58 , 66 . Preferably, a sufficiently large volume of fluid is initially flowed out of the test formation 82 , so that undesired fluids, such as drilling fluid, etc., in the formation are withdrawn from the formation. When one or more sensors, such as a resistivity or other fluid property or fluid identification sensor 102 , indicates that representative desired formation fluid is flowing into the assembly 86 , the lower valve 58 is closed. Note that the sensor 102 may be of the type which is utilized to indicate the presence and/or identity of solid matter in the formation fluid flowed into the assembly 86 . Pressure may then be applied to the string 87 at the earth's surface to flow the undesired fluid out through check valves 104 and into the disposal formation 84 . The lower valve 58 may then be opened again to flow further fluid from the test formation 82 into the assembly 86 . This process may be repeated as many times as desired to flow substantially any volume of fluid from the formation 82 into the assembly 86 , and then into the disposal formation 84 . Data acquired by the gauges 38 and/or sensors 102 while fluid is flowing from the formation 82 through the assembly 86 (when the valves 58 , 66 are open), and while the formation 82 is shut in (when the valve 58 is closed) may be analyzed after or during the test to determine characteristics of the formation 82 . Of course, gauges and sensors of any type may be positioned in other portions of the assembly 86 , such as in the waste chambers 22 , between the valves 58 , 66 , etc. For example, pressure and temperature sensors and/or gauges may be positioned between the valves 58 , 66 , which would enable the acquisition of data useful for injection testing of the disposal zone 84 , during the time the lower valve 58 is closed and fluid is flowed from the assembly 86 outward into the formation 84 . It will be readily appreciated that, in this fluid flowing process as described above, the valve 58 is used to permit flow upwardly therethrough, and then the valve is closed when pressure is applied to the string 87 to dispose of the fluid. Thus, the valve 58 could be replaced by the check valve 90 , or the check valve may be supplied in addition to the valve as depicted in FIG. 2 . If a difference in formation pressure between the formations 82 , 84 is used to flow fluid from the formation 82 into the assembly 86 , then a variable choke 88 may be used to regulate this fluid flow. Of course, the variable choke 88 could be provided in addition to other flow control devices, such as the valve 58 and check valve 90 , without departing from the principles of the present invention. If a pump 94 is used to draw fluid into the assembly 86 , no flow control devices may be needed between the disposal formation 84 and the test formation 82 , the same or similar flow control devices depicted in FIG. 2 may be used, or other flow control devices may be used. Note that, to dispose of fluid drawn into the assembly 86 , the pump 94 is operated with the valve 66 closed. In a similar manner, the check valves 104 of the disposal sub 96 may be replaced with other flow control devices, other types of flow control devices, etc. To provide separation between the low density fluid in the string 87 and the fluid drawn into the assembly 86 from the test formation 82 , a fluid separation device or plug 106 which may be reciprocated within the assembly 86 may be used. The plug 106 would also aid in preventing any gas in the fluid drawn into the assembly 86 from being transmitted to the earth's surface. An acceptable plug for this application is the Omega™ plug available from Halliburton Energy Services, Inc. Additionally, the plug 106 may have a fluid sampler 108 attached thereto, which may be activated to take a sample of the formation fluid drawn into the assembly 86 when desired. For example, when the sensor 102 indicates that the desired representative formation fluid has been flowed into the assembly 86 , the plug 106 may be deployed with the sampler 108 attached thereto in order to obtain a sample of the formation fluid. The plug 106 may then be reverse circulated to the earth's surface by opening the circulation valve 100 . Of course, in that situation, the plug 106 should be retained uphole from the valve 100 . A nipple, no-go 110 , or other engagement device may be provided to prevent the plug 106 from displacing downhole past the disposal sub 96 . When applying pressure to the string 87 to flow the fluid in the assembly 86 outward into the disposal formation 84 , such engagement between the plug 106 and the device 110 may be used to provide a positive indication at the earth's surface that the pumping operation is completed. Additionally, a no-go or other displacement limiting device could be used to prevent the plug 106 from circulating above the upper valve 44 to thereby provide a type of downhole safety valve, if desired. The sampler 108 could be configured to take a sample of the fluid in the assembly 86 when the plug 106 engages the device 110 . Note, also, that use of the device 110 is not necessary, since it may be desired to take a sample with the sampler 108 of fluid in the assembly 86 below the disposal sub 96 , etc. The sampler could alternatively be configured to take a sample after a predetermined time period, in response to pressure applied thereto (such as hydrostatic pressure), etc. An additional one of the plug 106 may be deployed in order to capture a sample of the fluid in the assembly 86 between the plugs, and then convey this sample to the surface, with the sample still retained between the plugs. This may be accomplished by use of a plug deployment sub, such as that representatively depicted in FIG. 3 . Thus, after fluid from the formation 82 is drawn into the assembly 86 , the second plug 106 is deployed, thereby capturing a sample of the fluid between the two plugs. The sample may then be circulated to the earth's surface between the two plugs 106 by, for example, opening the circulating valve 100 and reverse circulating the sample and plugs uphole through the string 87 . Referring additionally now to FIG. 3, a fluid separation device or plug deployment sub 112 embodying principles of the present invention is representatively depicted. A plug 106 is releasably secured in a housing 114 of the sub 112 by positioning it between two radially reduced restrictions 116 . If the plug 106 is an Omega™ plug, it is somewhat flexible and can be made to squeeze through either of the restrictions 116 if a sufficient pressure differential is applied across the plug. Of course, either of the restrictions could be made sufficiently small to prevent passage of the plug 106 therethrough, if desired. For example, if it is desired to permit the plug 106 to displace upwardly through the assembly 86 above the sub 112 , but not to displace downwardly past the sub 112 , then the lower restriction 116 may be made sufficiently small, or otherwise configured, to prevent passage of the plug therethrough. A bypass passage 118 formed in a sidewall of the housing 114 permits fluid flow therethrough from above, to below, the plug 106 , when a valve 120 is open. Thus, when fluid is being drawn into the assembly 86 in the method 80 , the sub 112 , even though the plug 106 may remain stationary with respect to the housing 114 , does not effectively prevent fluid flow through the assembly. However, when the valve 120 is closed, a pressure differential may be created across the plug 106 , permitting the plug to be deployed for reciprocal movement in the string 87 . The sub 112 may be interconnected in the assembly 86 , for example, below the upper valve 66 and below the plug 106 shown in FIG. 2 . If a pump, such as pump 94 is used to draw fluid from the formation 82 into the assembly 86 , then use of the low density fluid in the string 87 is unnecessary. With the upper valve 66 closed and the lower valve 58 open, the pump 94 may be operated to flow fluid from the formation 82 into the assembly 86 , and outward through the disposal sub 96 into the disposal formation 84 . The pump 94 may be any conventional pump, such as an electrically operated pump, a fluid operated pump, etc. Referring additionally now to FIG. 4, another method 130 of performing a formation test embodying principles of the present invention is representatively depicted. The method 130 is described herein as being used in a “rigless” scenario, i.e., in which a drilling rig is not present at the time the actual test is performed, but it is to be clearly understood that such is not necessary in keeping with the principles of the present invention. Note that the method 80 could also be performed rigless, if a downhole pump is utilized in that method. Additionally, although the method 130 is depicted as being performed in a subsea well, a method incorporating principles of the present invention may be performed on land as well. In the method 130 , a tubular string 132 is positioned in the well, preferably after a test formation 134 and a disposal formation 136 have been perforated. However, it is to be understood that the formations 134 , 136 could be perforated when or after the string 132 is conveyed into the well. For example, the string 132 could include perforating guns, etc., to perforate one or both of the formations 134 , 136 when the string is conveyed into the well. The string 132 is preferably constructed mainly of a composite material, or another easily milled/drilled material. In this manner, the string 132 may be milled/drilled away after completion of the test, if desired, without the need of using a drilling or workover rig to pull the string. For example, a coiled tubing rig could be utilized, equipped with a drill motor, for disposing of the string 132 . When initially run into the well, the string 132 may be conveyed therein using a rig, but the rig could then be moved away, thereby providing substantial cost savings to the well operator. In any event, the string 132 is positioned in the well and, for example, landed in a subsea wellhead 138 . The string 132 includes packers 140 , 142 , 144 . Another packer may be provided if it is desired to straddle the test formation 134 , as the test formation 82 is straddled by the packers 24 , 32 shown in FIG. 2 . The string 132 further includes ports 146 , 148 , 150 spaced as shown in FIG. 4, i.e., ports 146 positioned below the packer 140 , ports 148 between the packers 142 , 144 , and ports 150 above the packer 144 . Additionally the string 132 includes seal bores 152 , 154 , 156 , 158 and a latching profile 160 therein for engagement with a tester tool 162 as described more fully below. The tester tool 162 is preferably conveyed into the string 132 via coiled tubing 164 of the type which has an electrical conductor 165 therein, or another line associated therewith, which may be used for delivery of electrical power, data transmission, etc., between the tool 162 and a remote location, such as a service vessel 166 . The tester tool 162 could alternatively be conveyed on wireline or electric line. Note that other methods of data transmission, such as acoustic, electromagnetic, fiber optic etc. may be utilized in the method 130 , without departing from the principles of the present invention. A return flow line 168 is interconnected between the vessel 166 and an annulus 170 formed between the string 132 and the wellbore 12 above the upper packer 144 . This annulus 170 is in fluid communication with the ports 150 and permits return circulation of fluid flowed to the tool 162 via the coiled tubing 164 for purposes described more fully below. The ports 146 are in fluid communication with the test formation 134 and, via the interior of the string 132 , with the lower end of the tool 162 . As described below, the tool 162 is used to pump fluid from the formation 134 , via the ports 146 , and out into the disposal formation 136 via the ports 148 . Referring additionally now to FIG. 5, the tester tool 162 is schematically and representatively depicted engaged within the string 132 , but apart from the remainder of the well as shown in FIG. 4 for illustrative clarity. Seals 172 , 174 , 176 , 178 sealingly engage bores 152 , 154 , 156 , 158 , respectively. In this manner, a flow passage 180 near the lower end of the tool 162 is in fluid communication with the interior of the string 132 below the ports 148 , but the passage is isolated from the ports 148 and the remainder of the string above the seal bore 152 ; a passage 182 is placed in fluid communication with the ports 148 between the seal bores 152 , 154 and, thereby, with the disposal formation 136 ; and a passage 184 is placed in fluid communication with the ports 150 between the seal bores 156 , 158 and, thereby, with the annulus 170 . An upper passage 186 is in fluid communication with the interior of the coiled tubing 164 . Fluid is pumped down the coiled tubing 164 and into the tool 162 via the passage 186 , where it enters a fluid motor or mud motor 188 . The motor 188 is used to drive a pump 190 . However, the pump 190 could be an electrically-operated pump, in which case the coiled tubing 164 could be a wireline and the passages 186 , 184 , seals 176 , 178 , seal bores 156 , 158 , and ports 150 would be unnecessary. The pump 190 draws fluid into the tool 162 via the passage 180 , and discharges it from the tool via the passage 182 . The fluid used to drive the motor 188 is discharged via the passage 184 , enters the annulus, and is returned via the line 168 . Interconnected in the passage 180 are a valve 192 , a fluid property sensor 194 , a variable choke 196 , a valve 198 , and a fluid identification sensor 200 . The fluid property sensor 194 may be a pressure, temperature, resistivity, density, flow rate, etc. sensor, or any other type of sensor, or combination of sensors, and may be similar to any of the sensors described above. The fluid identification sensor 200 may be a nuclear magnetic resonance sensor, an acoustic sand probe, or any other type of sensor, or combination of sensors. Preferably, the sensor 194 -is used to obtain data regarding physical properties of the fluid entering the tool 162 , and the sensor 200 is used to identify the fluid itself, or any solids, such as sand, carried therewith. For example, if the pump 190 is operated to produce a high rate of flow from the formation 134 , and the sensor 200 indicates that this high rate of flow results in an undesirably large amount of sand production from the formation, the operator will know to produce the formation at a lower flow rate. By pumping at different rates, the operator can determine at what fluid velocity sand is produced, etc. The sensor 200 may also enable the operator to tailor a gravel pack completion to the grain size of the sand identified by the sensor during the test. The flow controls 192 , 196 , 198 are merely representative of flow controls which may be provided with the tool 162 . These are preferably electrically operated by means of the electrical line 165 associated with the coiled tubing 164 as described above, although they may be otherwise operated, without departing from the principles of the present invention. After exiting the pump 190 , fluid from the formation 134 is discharged into the passage 182 . The passage 182 has valves 202 , 204 , 206 , sensor 208 , and sample chambers 210 , 212 associated therewith. The sensor 208 may be of the same type as the sensor 194 , and is used to monitor the properties, such as pressure, of the fluid being injected into the disposal formation 136 . Each sample chamber has a valve 214 , 216 for interconnecting the chamber to the passage 182 and thereby receiving a sample therein. Each sample chamber may also have another valve 218 , 220 (shown in dashed lines in FIG. 5) for discharge of fluid from the sample chamber into the passage 182 . Each of the valves 202 , 204 , 206 , 214 , 216 , 218 , 220 may be electrically operated via the coiled tubing 164 electrical line as described above. The sensors 194 , 200 , 208 may be interconnected to the line 165 for transmission of data to a remote location. Of course, other means of transmitting this data, such as acoustic, electromagnetic, etc., may be used in addition, or in the alternative. Data may also be stored in the tool 162 for later retrieval with the tool. To perform a test, the valves 192 , 198 , 204 , 206 are opened and the pump 190 is operated by flowing fluid through the passages 184 , 186 via the coiled tubing 164 . Fluid from the formation 134 is, thus, drawn into the passage 180 and discharged through the passage 182 into the disposal formation 136 as described above. When one or more of the sensors 194 , 200 indicate that desired representative formation fluid is flowing through the tool 162 , one or both of the samplers 210 , 212 is opened via one or more of the valves 214 , 216 , 218 , 220 to collect a sample of the formation fluid. The valve 206 may then be closed, so that the fluid sample may be pressurized to the formation 134 pressure in the samplers 210 , 212 before closing the valves 214 , 216 , 218 , 220 . One or more electrical heaters 222 may be used to keep a collected sample at a desired reservoir temperature as the tool 162 is retrieved from the well after the test. Note that the pump 190 could be operated in reverse to perform an injection test on the formation 134 . A microfracture test could also be performed in this manner to collect data regarding hydraulic fracturing pressures, etc. Another formation test could be performed after the microfracture test to evaluate the results of the microfracture operation. As another alternative, a chamber of stimulation fluid, such as acid, could be carried with the tool 162 and pumped into the formation 134 by the pump 190 . Then, another formation test could be performed to evaluate the results of the stimulation operation. Note that fluid could also be pumped directly from the passage 186 to the passage 180 using a suitable bypass passage 224 and valve 226 to directly pump stimulation fluids into the formation 134 , if desired. The valve 202 is used to flush the passage 182 with fluid from the passage 186 , if desired. To do this, the valves 202 , 204 , 206 are opened and fluid is circulated from the passage 186 , through the passage 182 , and out into the wellbore 12 via the port 148 . Referring additionally now to FIG. 6, another method 240 embodying principles of the present invention is representatively illustrated. The method 240 is similar in many respects to the method 130 described above, and elements shown in FIG. 6 which are similar to those previously described are indicated using the same reference numbers. In the method 240 , a tester tool 242 is conveyed into the wellbore 12 on coiled tubing 164 after the formations 134 , 136 have been perforated, if necessary. Of course, other means of conveying the tool 242 into the well may be used, and the formations 134 , 136 may be perforated after conveyance of the tool into the well, without departing from the principles of the present invention. The tool 242 differs from the tool 162 described above and shown in FIGS. 4 & 5 in part in that the tool 242 carries packers 244 , 246 , 248 thereon, and so there is no need to separately install the tubing string 132 in the well as in the method 130 . Thus, the method 240 may be performed without the need of a rig to install the tubing string 132 . However, it is to be clearly understood that a rig may be used in a method incorporating principles of the present invention. As shown in FIG. 6, the tool 242 has been conveyed into the well, positioned opposite the formations 134 , 136 , and the packers 244 , 246 , 248 have been set. The upper packers 244 , 246 are set straddling the disposal formation 136 . The passage 182 exits the tool 242 between the upper packers 244 , 246 , and so the passage is in fluid communication with the formation 136 . The packer 248 is set above the test formation 134 . The passage 180 exits the tool 242 below the packer 248 , and the passage is in fluid communication with the formation 134 . A sump packer 250 is shown set in the well below the formation 134 , so that the packers 248 , 250 straddle the formation 134 and isolate it from the remainder of the well, but it is to be clearly understood that use of the packer 250 is not necessary in the method 240 . Operation of the tool 242 is similar to the operation of the tool 162 as described above. Fluid is circulated through the coiled tubing string 164 to cause the motor 188 to drive the pump 190 . In this manner, fluid from the formation 134 is drawn into the tool 242 via the passage 180 and discharged into the disposal formation 136 via the passage 182 . Of course, fluid may also be injected into the formation 134 as described above for the method 130 , the pump 190 may be electrically operated (e.g., using the line 165 or a wireline on which the tool is conveyed), etc. Since a rig is not required in the method 240 , the method may be performed without a rig present, or while a rig is being otherwise utilized. For example, in FIG. 6, the method 240 is shown being performed from a drill ship 252 which has a drilling rig 254 mounted thereon. The rig 254 is being utilized to drill another wellbore via a riser 256 interconnected to a template 258 on to the seabed, while the testing operation of the method 240 is being performed in the adjacent wellbore 12 . In this manner, the well operator realizes significant cost and time benefits, since the testing and drilling operations may be performed simultaneously from the same vessel 252 . Data generated by the sensors 194 , 200 , 208 may be stored in the tool 242 for later retrieval with the tool, or the data may be transmitted to a remote location, such as the earth's surface, via the line 165 or other data transmission means. For example, electromagnetic, acoustic, or other data communication technology may be utilized to transmit the sensor 194 , 200 , 208 data in real time. Of course, a person skilled in the art would, upon a careful reading of the above description of representative embodiments of the present invention, readily appreciate that modifications, additions, substitutions, deletions and other changes may be made to these embodiments, and such changes are contemplated by the principles of the present invention. For example, although the methods 10 , 80 , 130 , 240 are described above as being performed in cased wellbores, they may also be performed in uncased wellbores, or uncased portions of wellbores, by exchanging the described packers, tester valves, etc. for their open hole equivalents. The foregoing detailed description is to be clearly understood as being given by way of illustration and example only.

Methods and apparatus are provided which permit well testing operations to be performed downhole in a subterranean well. In various described methods, fluids flowed from a formation during a test may be disposed of downhole by injecting the fluids into the formation from which they were produced, or by injecting the fluids into another formation. In several of the embodiments of the invention, apparatus utilized in the methods permit convenient retrieval of samples of the formation fluids and provide enhanced data acquisition for monitoring of the test and for evaluation of the formation fluids.

This application claims priority to U.S. Provisional patent application Ser. No. 60/052,443, of Roos et al.; filed Jul. 14, 1997, for COMMON AIR INTERFACE, incorporated herein by reference. This patent document relates to a common air interface described in a series of patent documents filed concurrently herewith. Related patent documents are: U.S. patent application Ser. No. 09/115,098, filed Jul. 13, 1998, of Joshi et al.; for SYSTEM AND METHOD FOR IMPLEMENTING TERMINAL TO TERMINAL CONNECTIONS VIA A GEOSYNCHRONOUS EARTH ORBIT SATELLITE, now U.S. Pat. No. 6,278,876; U.S. patent application Ser. No. 09/115,097, filed Jul. 13, 1998, of Roos, et al.; for MOBILE SATELLITE SYSTEM HAVING AN IMPROVED SIGNALING CHANNEL, U.S. patent application Ser. No. 09/115,096; filed Jul. 13, 1998, of Noerpel, et al.; for SPOT BEAM SELECTION IN A MOBILE SATELLITE COMMUNICATION SYSTEM, now U.S. Pat. No. 6,233,451; U.S. patent application Ser. No. 09/115,101, filed Jul. 13, 1998, of Noerpel, et al.; for PAGING RECEPTION ASSURANCE IN A MULTIPLY REGISTERED WIRELESS TRANSCEIVER, now U.S. Pat. No. 6,282,178; U.S. patent application Ser. No. 09/115,095, filed Jul. 13, 1998, of Joshi, et al.; for IMMEDIATE CHANNEL ASSIGNMENT IN A WIRELESS SYSTEM, U.S. patent application Ser. No. 09/115,099, filed Jul. 13, 1998, of Joshi, et al.; for ERROR AND FLOW CONTROL IN A SATELLITE COMMUNICATIONS SYSTEM, now U.S. Pat. No. 6,289,482; U.S. patent application Ser. No. 09/115,100, filed Jul. 13, 1998, of Roos, et al.; for SYNCHRONIZATION OF A MOBILE SATELLITE SYSTEM WITH SATELLITE SWITCHING, all of which are incorporated herein by reference. BACKGROUND OF THE INVENTION The present invention relates to cellular and satellite communications. More particularly, the invention relates to a method and a system for providing signaling bursts for maintaining communications channel transmissions during periods of voice inactivity during ongoing voice communications between a transmitter and a receiver in a time division multiple access (TDMA) mobile satellite communication system. A mobile satellite communication system such as the Geosynchronous Earth Orbit Mobile (GEM) network discussed herein, typically includes one or more satellites, at least one fixed ground terminal such as a gateway system (GS) and several mobile access terminals (ATs). The access terminals typically communicate with the public switched telephone network (PSTN) or other mobile terminals via an air communication interface between the satellite and the gateway. Using the mobile access terminals, the satellite system provides a variety of telephony services. Satellite telephony systems as described herein share call processing information with terrestrial systems such as the GSM cellular system to allow compatibility between the satellite, cellular, and the public switch telephone network services. The terrestrial standards such as GSM may not apply directly to the mobile satellite communication system, more particularly the satellite air interface poses physical constraints not accounted for in the GSM architecture. A number of communication systems utilizing satellites and small mobile terminals provide voice and other information communication. In all such systems, the bandwidth and satellite power associated with the communication links may be expensive and wasteful of limited resources. In addition, the mobile access terminals such as hand-held terminals (HHTs), which are often small, hand-held devices, are constrained by power consumption and related battery life concerns. In maintaining an active voice communications channel, however, information must be transmitted on a regular basis for synchronization between the satellite and the access terminal, e.g., for timing, frequency, and power parameters. During voice communications, periods of voice inactivity may occur approximately half of the time. Therefore, appropriate design of burst formats, combined with voice activity detection, may provide significant power reduction. A number of specific concerns are associated with the form of information communications necessary for maintaining a communications channel, including power control information transfer requirements, power level consistency in the presence of highly variable power amplifiers, background noise level and characteristic communication, support for frequency and timing parameter tracking, timeliness of information delivery, and robust communications. Thus, there exists a need for a method and a system for performing Keep-Alive Burst (KAB) communications during periods of voice inactivity to maintain the integrity of the voice communication transmissions over a communications channel, and provide acceptable performance with a minimum amount of power being used by the satellite and access terminal systems. SUMMARY OF THE INVENTION In the following description, a satellite communications system is described. As will be appreciated by a skilled artist, however, the teachings of the present invention apply to many communications systems, not just satellite-based systems. Thus, references herein to satellite systems should be understood as being directed to specific embodiments, as opposed to the invention generally. Accordingly, the present invention, in particular embodiments, addresses a key opportunity for power savings at both the satellite and the access terminals to limit transmission of significant power to those times when voice communications is active. During periods of silence, which typically occur about sixty percent of the time, much less power may be transmitted. Nonetheless, for a variety of reasons discussed herein, some power continues to be required for transmissions during periods of voice inactivity in the form of bursts that are transmitted during such periods to maintain the integrity of the communications channel. Information transmitted during voice inactivity by such keep-alive bursts (KABs) may be categorized into two types of information, namely, explicit digital information and information implicit in the waveforms transmitted. By adopting a burst format which accounts for the necessary explicit and implicit information required for transmission during keep-alive bursts, a combination of various features in terms of power modulation in burst format results in reduced power and delay, and improves performance when compared with conventional techniques. Briefly summarized, the present invention relates a system and method employing an access terminal for maintaining discontinuous communications including a gateway receiver for receiving the discontinuous information, a radio frequency (RF) communication link via geosynchronous earth orbit satellite for conveying multiple communication channels using time division multiple access (TDMA), the access terminal initiating information communication with the receiver via at least one of the multiple communication channels. The access terminal further includes a memory for storing protocol processing information and a transmitter for establishing the radio frequency communication link to the receiver of the terrestrial gateway system. The access terminal memory provides for storing of a signal pattern or protocol assigned to the access terminal by the gateway receiver or transmission of keep-alive bursts by the transmitter during periods of inactivity to maintain information communication with the receiver. It will be understood that both the foregoing and general description in the following detailed description are exemplary and intended to provide further explanation of the invention as claimed. The accompanying drawings provide an understanding of the invention as described in the preferred embodiments to illustrate the invention and serve to explain the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram of a mobile satellite communication system in accordance with the present invention; FIG. 2 is a block diagram of a preferred embodiment of a mobile access terminal for use in the mobile satellite communication system of FIG. 1; FIG. 3 shows a keep-alive burst (KAB) structure timing diagram; FIG. 4 illustrates KAB transmission allocation positions in active communications traffic; FIG. 5 shows symbol position usage at the beginning of the KAB bursts; FIG. 6 shows the power distribution for the keep-alive bursts at the beginning of each burst; FIG. 7 is a table illustrating symbol utilization in the middle of channel TCH 2 ; FIG. 8 is a power distribution graph showing the power use per symbol position in channel TCH 2 ; FIG. 9 is a flowchart illustrating the determination of keep-alive burst positions; FIG. 10 is a flowchart illustrating the operation of keep-alive burst transmissions; and FIG. 11 is a flowchart illustrating the receive operation associated with the keep-alive burst transmissions of FIG. 10 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings and particularly to FIG. 1, a preferred embodiment of a mobile satellite communication system 10 is illustrated. The mobile communication system 10 , herein a Geosynchronous Earth Orbit Mobile satellite system (GEM) includes several mobile access terminals 12 and one or more satellites 14 . One or more gateway stations 16 (GS) are coupled to public switch telephone networks 18 (PSTN). The access terminal 12 is typically a hand-held telephone or vehicle-mounted telephone, but, as described in the present embodiment, the access terminal 12 may provide operation both as a GEM access terminal and as an GSM cellular telephone. While being used with the satellite communication systems described herein, the access terminal 12 communicates over an L-band frequency with a particular spot beam 20 with the satellite 14 . Each spot beam 20 is associated with a predetermined geographic region. The terrestrial gateway 16 communicates with the satellite 14 over a Ku-band frequency. The satellite 14 includes transponders for translating between the L-band spot beam 20 signals used by the access terminals 12 and the Ku-band 22 signals used by the gateway 16 . The gateway 16 interfaces with the terrestrial telephony carrier, such as PSTN 18 , and may also interface with a conventional cellular network such as GSM. Accordingly, users may place telephone calls using the access terminal 12 to either land line or cellular telephone users. As illustrated in FIG. 1, a plurality of gateways 16 may be employed, each providing similar functions and being employed to access, for example, respective public switched telephone networks 18 . The satellite 14 provides L-band-to-L-band bent pipe single hop communications, as well as satellite switched communications to support communications between the users of the access terminals 12 . At satellite 14 , the L-band 20 uplink and downlink are transmitted via multiple L-band spot beams 20 . Subscribers to the system 10 have unique telephone numbers allowing them to receive telephone calls when they are registered to receive pages from either the GEM or the GSM cellular network. Registration is automatic when the access terminal 12 is turned on, such that a registration procedure locates the access terminal 12 within a particular spot beam coverage area. In addition to originating calls, the access terminals 12 can receive calls from any terrestrial facility by connecting the call through the gateway station 16 , at which the gateway 16 determines the location of the access terminal 12 and sends a paging message to the access terminal 12 to announce the incoming call. The system 10 uses a low rate encoded or ciphered voice transmission. In the described embodiments, the access terminals 12 are provided with dual mode operation allowing for voice communications either via satellite or via the local cellular system, e.g., GEM and GSM as discussed herein. The gateway 16 provides for user mobility as users travel with the access terminal 12 from spot beam to spot beam. Additionally, the communication channels carried via the satellite 14 provides space segment resources used for control functions, i.e., one or more channels in each L-band spot beam 20 are control channels, e.g., the gateway 16 may place a forward control signal in each L-band spot beam 20 to allow synchronization of the access terminals 12 and to carry network control information from the gateway 16 to the access terminals 12 . The forward control channels allow the access terminals 12 to acquire a satellite carrier and identify the L-band spot beam 20 and gateway station 16 which originates the signal. The gateway 16 uses the forward control channel to page access terminals 12 using unique addresses to announce mobile terminated calls. Each L-band spot beam 20 preferably contains a return direction signaling channel that access terminals 12 use to initiate and register calls with the gateway 16 . During a call, in-band low data rate control channels are preferably available between the access terminals 12 and the gateway 16 for call supervision, power control, and to initiate call termination. For example, during burst communication between the access terminal 12 and the satellite 14 , a threshold signal may be established relating to the strength of the transmitted burst for setting a power control bit based on a comparison of received signal strength with threshold values. In addition to such information being transmitted during active voice communications, certain information must also be transmitted during voice inactivity by keep-alive bursts (KABs) which can be categorized as one of two types, namely, explicit digital information, and implicit information in the waveforms transmitted. Explicit digital information provided by the keep-alive bursts include a description of the background sounds present at the transmitter's microphone, and commands and status messages associated with power control. Information implicit in the waveforms transmitted include the power level of the signal, the signal quality as perceived by the receiver, and information used in tracking both carrier frequency offset and symbol timing error for synchronization between the transmitter and receiver. The system 10 contains considerable operational flexibility both from the standpoint of network features and mobile terminal capabilities. The gateway 16 is a conventional gateway as understood in the art, which includes a mobile switching center (MSC), base station controllers (BSCs), base transceiver stations (BTS), and radio frequency units. As is understood by those skilled in the art, the MSC allows communications with the public switch telephone network or other mobile switching centers. The MSC is connected preferably with an A-interface such as a standard E 1 or E 3 line with the BSC. The BSC is then connected through a communications channel such as a T 1 line to one or more BTSs which may communicate via radio frequency (RF) communications to the access terminal 12 . Telephony communications may be originated with the access terminal 12 by transmitting initialization data to the satellite 14 of the space segment over a control channel which then communicates down to the gateway 16 . The control channel is transmitted over a time slot within a frequency assigned to the spot beam 20 having a coverage area surrounding the access terminal 12 . At the gateway 16 , the call is transmitted via a radio frequency channel to the BTS assigned to the spot beam 20 servicing the access terminal 12 . From the BTS the call is routed to the BSC and then to the MSC, from which the call is routed to either the PSTN or another MSC. Thereafter, a communications channel is established through the entire gateway 16 and a subscriber using the access terminal 12 may communicate over the established communications channel. Calls may also originate from either the PSTN or a GSM cellular network by entering the gateway 16 at the MSC which routes information to the BSC for paging the access terminal 12 via the appropriate BTS. After the access terminal 12 responds to the page from the BTS, a communications channel is then established. The access terminal 12 as shown in FIG. 2 includes a satellite module 40 , a satellite antenna 42 , a cellular module 44 , and a user interface module 46 . The satellite module 40 is coupled to the user interface module 46 , the cellular module 44 , and the satellite antenna 42 . Preferably, the satellite antenna 42 is a physically small antenna, such as a helix type antenna. The satellite module 40 includes a modem and TDMA unit 48 , an RF coder and decoder (codec) 50 , a burst transmitter 52 , a receiver 54 , and a transmit or receive (T/R) switch 56 . In the preferred embodiment, the modem 48 is connected to the RF codec 50 , and the RF codec 50 is connected to the burst transmitter 52 and to the receiver 54 . The T/R switch 56 is connected to the burst transmitter 52 , the receiver 54 , and the satellite antenna 42 . Within the satellite module 40 , the modem 48 converts speech or data samples to and from channel symbols using quadrature phase shift key modulation (QPSK). QPSK is preferably performed digitally by an application-specific integrated circuit or alternatively on a commercial available digital signal processor. The RF codec 50 converts channel symbols from the modem 48 into baseband I and Q signals that are transmitted to the burst transmitter 52 . In the receive direction, the RF codec 50 processes an IF signal 53 from the receiver 54 for input to the modem 48 . The burst transmitter 52 converts the I and Q signals from the RF codec 50 up to a desired frequency, preferably an L-band frequency, for transmission by the first antenna 42 . The receiver 54 converts a received L-band signal from the first antenna 42 into the IF signal 53 sent to the RF codec 50 . The T/R switch 56 allows the access terminal 12 to either transmit data or receive data. The access terminal 12 also includes a synthesizer 58 that provides a fixed local oscillator (LO) signal for the RF codec 50 . The synthesizer 58 includes a variable local oscillator for channel tuning within the satellite module 40 and generates data clock signals for the modem 48 . Both the fixed local oscillator and the variable local oscillator within the synthesizer 58 may be adjusted based on commands from either the gateway 16 or from another access terminal 12 . In the preferred embodiment, the synthesizer 58 is connected to the receiver 54 and to the cellular module 44 . The user interface module 46 includes an audio and codec unit 59 , a voice processing unit 60 , a controller 62 , an input/output (I/O) interface 64 , and a memory 66 . Preferably, each element within the user interface module 46 communicates with the other user interface elements. The voice processing unit 60 includes a voice transcoder that performs source coding to compress the digital 64 Kb/s PCM signal. Specifically, an encoder running on a programmable digital signal processor, such as a low delay CELP encoder, compresses the 64 Kb/s PCM signal into approximately a 3.6 Kb/s encoded signal. Alternatively, the encoder may be a multiband excited (MBE) type 3.6 Kb/s encoder that is well known to those skilled in the art. The controller 62 preferably provides a multitasking firmware environment for monitoring and controlling the mobile terminal hardware. The controller 62 may occupy the same processor as the voice transcoder or may optionally be disposed on a separate processor. Preferably, the controller 62 includes an I/O interface 64 that provides a communication interface with a user. The I/O interface 64 includes a keypad for data entry such as a phone number, a display, a data port for digital communication such as a facsimile transmission, and a smart card interface as specified for GSM. The cellular module 44 allows the access terminal 12 to communicate with a cellular system over a second antenna 61 . The second antenna is a linearly polarized whip meeting cellular system standards and the cellular module 44 uses standard components, such as a GSM chip set, known to those skilled in the art. Preferably, the access terminal 12 operates in a first mode where the access terminal 12 functions as a conventional cellular phone. In a second mode, the access terminal 12 preferably operates so that the access terminal 12 communicates with the satellite 14 . A battery 68 is provided for portable operation of the access terminal 12 . The preferred access terminal 12 has many advantages. For example, the access terminal 12 provides dual-mode operation, either cellular or satellite. Also, the access terminal 12 is mobile and provides high quality digital voice. Further, the access terminal 12 allows for paging and messaging, transmission at a 2400 or 4800 bps data rate via the data port, and provides a convenient cellular-like interface. Also, the access terminal 12 may transmit on a single channel using a single time slot within a carrier signal allowing many other access terminals 12 to transmit over the same carrier. Thus, the access terminal 12 efficiently transmits over L-band spot beam 20 frequency resources. The following description relates the requirements to individual design aspects of the keep-alive bursts. Note that the specific implementation defined centers around a framing design with the following features. Note that this burst arrangement is similar to that used in the Geosynchronous Earth Orbit Mobile system, but that the durations etc. have been selected to simplify the explanation while retaining the essential issues (i.e., active voice is transmitted in “traffic” bursts.) Traffic bursts are transmitted once every 40 mS and are 5 mS in duration. This 5 mS period is referred to as a slot, and the 40 mS period is a frame. Traffic bursts are transmitted using Coherent-QPSK modulation. One hundred symbols are transmitted in each traffic burst, with additional time within the 5 mS slot duration for waveform ramping, and guard time. FIG. 3 shows a KAB structure timing diagram having content and structure simultaneously satisfying the requirements for voice communications, as set forth in the following table. Requirement Implementation Approach Data transmission for voice 100 bps, requiring 4 bits per frame background sounds Data transmission for power 100 bps, requiring 4 bits perframe control Insensitivity to poor calibration Transmission of KAB's occurs at the of the linearity of power same power level as the traffic. That amplifiers is, power savings arise due to a reduction in the duration of trans- missions, not instantaneous power. Bursts must be very short. Synchronization or training infor- mation cannot be lengthy. The key implication of this is that coherent modulation cannot be supported (efficiently). Equal or better communications Differential Binary Phase Shift Keying performance (Bit Error Rates) (DBPSK) provides suitable perfor- than that achieved with traffic. mance. Approximately 2.5 dB is lost in performance, while 3 dB is gained in Energy-per-Bit. Hence, a slight performance improvement (˜0.5 dB) arises. Support for tracking of Carrier Short bursts provide very weak refer- Frequency Offset by the ences for frequency estimation. receiver. Hence, KAB's consist of two short bursts, separated in time to ensure good frequency estimation without ambiguity. Transmission of the two short bursts must be coherently related. Support for tracking of Symbol Timing estimation is relatively easy Timing by the receiver (compared with frequency). Ongoing transmission of short bursts is sufficient. Minimal delay in transmission of Transmit data once every frame. power control information. The contents of the keep-alive bursts include: 1. 4 bits (symbols) of power control information; 2. 4 bits of background noise information; and 3. 2 differential reference symbols (one per burst), generating a total of 10 transmitted symbols, spread equally over the two bursts. The separation between the bursts should be about half the length of the traffic bursts. Selection of this time depends on the following factors: Longer burst separations improve the accuracy of frequency error estimates; and shorter burst separations ensure that probability of ambiguity in the estimate of the phase difference between the two bursts is reduced. For example, with a 100 Hz error, and 2.5 mS between bursts, a phase change of 90° will occur between the bursts. Assuming that the phase relationship between the transmitted differential reference symbols is known, and that the Signal-to-Noise Ratio is reasonable, the 90° phase change is unlikely to get mistaken for the −270° phase change that would accompany a −300 Hz frequency error. The burst separation should permit location of the bursts to enable even distribution of power in time, as viewed by the satellite. The “Adjustable Time Offset” is randomly assigned to each terminal, such that the keep-alive bursts are approximately evenly spread in time when the cumulative power reaches the satellite. If the keep-alive bursts are fixed in time, then all carriers transmitting keep-alive bursts during a particular time slot will always be transmitting during the same instant and during that instant the power required of the satellite transponder will be higher than desired because every single carrier (both those transmitting voice bursts and those transmitting KABs) will be on simultaneously. There may be no benefit from the voice deactivation during that instant. Therefore, the KABs are distributed over time so that not every carrier transmitting KABs will transmit simultaneously. The randomly-assigned “Adjustable Time Offset” remains fixed during a call. Over all terminals, the offset is uniformly distributed between about 0 and 45 symbol periods. For this example, five periods would be an appropriate quantization of this setting. In some specific applications (differing number of bits in the keep-alive burst or different number of bits in the traffic burst), the numbers of bits do not divide evenly. For example, if the number of traffic bits were 99 instead of 100 in the previous example, there would be seven unique potential locations for the KABs (with Adjustable Time Offsets of 0, 5, 10, 15, 20, 25, 30, 35, and 40 bits; the offset of 45 bits would not allow the second KAB to fit within the traffic burst allocation). In this case, there will be 4 bits in the middle and at the end of the traffic burst allocation which will not have anything transmitted. Therefore, it is desired that the method used for distributing the KABs accommodate these possibilities. Some useful ways are: 1. Use Adjustable Time Offset values of 0, 1, 2, . . . , 44. This solution evenly distributes the KAB energy throughout the assigned time slots throughout the system, except that the first and last 4 bit frames have increasing/decreasing amounts of power (since there are five ways to assign the KAB offsets in the middle but only one way to assign them at the beginning and end). 2. Distribute the extra bits between the bursts as in these possible Adjustable Time Offsets as illustrated in FIG. 4, wherein the X's indicate possible locations of KAB burst energy, i.e., each X represents one bit. This distribution is even more uniformly spread than for option 1 above. Locations 0-3 are occupied {fraction (9/10)}th of the time; location 4 100% of the time, locations 5 through 8 {fraction (9/10)}ths of the time, etc. 3. Many other arrangements may be made that provide even more uniform distributions, such as distributing the 4 extra bits in all combinations of 1, 2, 3, and 4 extra bits in a row, scattered among the bursts. 4. The preceding approaches can use known, but varying, time offsets. For example, a pseudo-random sequence could be applied. The position of the transmission of the first KAB is derived from a 16 bit pseudo-random number. The eight least significant digits of the frame number (FN) of the original RACH transmitted by the AT 12 comprise the eight most significant bits of this pseudo-random number and eight least significant digits of either the telephone number called for mobile originated calls or the TMSI (IMSI) for all other cases (call termination, registration, detach, etc . . . ) include the eight least significant bits of this pseudo-random number. The resulting 16 bit number modulo 35 and modulo 54 points to the start of the transmission of the first KAB respectively for TCH 2 and TCH 3 . For TCH 4 , TCH 6 and TCH 9 the pointer is derived using the 16 bit number respectively modulo 70 , 108 , and 162 . The first KAB pointer is returned by the gateway in the Immediate Assignment Message. The pointer to the second KAB is implemented by the gateway and the AT 12 according to the traffic channel size. The pointer to the first KAB and the separation are selected to optimize toward a uniform power distribution per symbol position over time. Excluding duplication, each symbol slot except for the first and the last 4 next to the guard times, may be selected 5 times. FIG. 5 depicts the usage for the beginning of the burst. This is the same at the end. The keep-alive burst symbol position usage described herein provides a power distribution over time as illustrated in FIG. 6 . The power distribution is typically flat over the traffic time slots except for the symbol slot at the center. In the middle, the separation from the first pointer to the last pointer is illustrated in FIG. 7, which shows symbol utilization in the middle of channel TCH 2 . Thus, an elevated power usage over time is shown for the symbol position employed in the power distribution as illustrated in FIG. 8 . The same type of situation does not occur for channel TCH 3 . The derivatives have multiple power distribution symbol bumps in the half boundaries of the basic traffic channels (TCH 2 and TCH 3 ). FIG. 9 is a flow chart illustrating the determination of keep-alive burst positions during the course of voice communications over a traffic channel, and particularly the positioning of keep-alive bursts during periods of voice inactivity. Initially, the user initiates the call via access terminal 12 by transmitting a random access channel request (RACH) at step 100 . In the terminal to terminal call, the immediate assignment procedure provides that the access terminal 12 which originates the call, sends a channel request on the RACH with the called party number and GPS position. The access terminal 12 then waits for immediate assignment on the access grant channel (AGCH) of the corresponding, control channel (CCCH). Thus, at the same time, the gateway station 16 assigns the keep-alive burst position to the access terminal 12 via the AGCH at step 102 . The access terminal 12 and the gateway station 16 calculate the keep-alive burst positions, herein at least two keep-alive burst positions (SKAB 1 and SKAB 2 ) at step 104 . Thereafter, at step 106 the access terminal 12 uses the calculated keep-alive burst positions, SKAB 1 and SKAB 2 , to determine when to transmit keep alive bursts. At the same time, the gateway station 16 looks for the keep-alive bursts (KABs) at the calculated position. The same calculated positions are used in the opposite direction as well. With reference to FIG. 10, the transmit operation used by the access terminal 12 is illustrated as a program flow chart, wherein step 108 is used to wait for the beginning of a transmit time slot in the described time division multiplex access telephony system. Step 110 then determines whether voice communications is active or inactive. During periods of voice inactivity, step 112 is indicated from step 110 , step 112 causing the access terminal 12 to wait for SKAB 1 . Step 114 then transmits a keep-alive burst, and step 116 waits for the symbol indicating SKAB 2 . Step 118 is then used to transmit the second keep-alive burst, and program flow returns from step 120 to wait for the next frame, and returns the transmit operation to step 108 . Alternatively, if voice communications is active in the time slot, step 110 identifies voice activity and step 122 is used to transmit the voice burst, after which the access terminal 12 waits for the next frame at step 120 and waits for the beginning of the transmit's time slot at step 108 . The above-described transmit operation is illustrated for two keep-alive burst positions during periods of voice inactivity, as shown in FIG. 3 . The gateway station 16 performs a keep-alive burst receive operation as illustrated in the program flow chart of FIG. 11, wherein the gateway station 16 waits for the beginning of a receive time slot at step 124 . At step 126 , the gateway station 16 samples and stores the signal contained in the entire time slot received. The operation performed at step 128 determines if there exists a voice burst, a keep-alive burst, or other in the received time slots. Where a voice burst was received at step 128 , step 130 then demodulates the voice transmission, and the gateway station 16 waits for the next frame at step 134 , from which program flow returns to wait for the beginning of the receive time slot at step 124 . Where a keep-alive burst was received at step 128 , step 132 demodulates the keep-alive burst beginning at positions SKAB 1 and SKAB 2 , and upon completion of the keep-alive burst demodulation, program flow returns via step 134 . If nothing has been received in the receive time slots, a step 128 does not demodulate transmissions, but rather returns to wait for the next frame at step 134 , returning program flow as described above to wait for the beginning of the received time slot at step 124 . It should be appreciated that a wide range of changes and modifications may be made to the preferred embodiments as described herein. Thus, it is intended that the foregoing detailed description be regarded as illustrative rather than limiting and that the following claims, including all equivalents, are intended to define the scope of the invention.

A system and method employing an access terminal for maintaining discontinuous communications including a gateway receiver for receiving the discontinuous information, a radio frequency (RF) communication link via geosynchronous earth orbit satellite for conveying multiple communication channels using time division multiple access (TDMA), the access terminal initiating information communication with the receiver via at least one of the multiple communication channels. The access terminal further includes a memory for storing protocol processing information and a transmitter for establishing the radio frequency communication link to the receiver of the terrestrial gateway system. The access terminal memory provides for destroying of a signal pattern or protocol assigned to the access terminal by the gateway receiver or transmission of keep-alive bursts by the transmitter during periods of inactivity to maintain information communication with the receiver.

FIELD OF THE INVENTION [0001] The present invention regards a therapy for renal diseases and the ensuing alterations of the renal function, in particular, even though not exclusively, of the renal diseases which develop in diabetic patients or who have been subjected to a chemotherapy antitumor treatment using a platinum derivative. BACKGROUND OF THE INVENTION [0002] The chronic renal disease and renal failure which derives therefrom are extremely frequent diseases even though under-diagnosed; actually, it is estimated that 17% of the adult population is affected by this disease. [0003] The most frequent renal disease is characterised by damaged renal glomerula. [0004] Renal diseases may be congenital or acquired; in particular the acquired ones may have various etiology: immunologic like the Goodpasture's syndrome, lupus nephritis and immunoglobulin A nephropathy. In the case of the immunologically mediated renal disease, the cause lies in the presence of a strong antigenic stimulus which triggers an immune reaction; dysmetabolic and in particular diabetic nephropathy, one of the most common causes of chronic renal disease. The prevalence is of 20-30% in patients suffering from type 1 diabetes and about 10% of the cases in patients suffering from type 2 diabetes. This is an insidious disease in that it is characterised by a particularly slow occurrence (up to 20-30 years from the occurrence of diabetes) and it is practically asymptomatic over a long period of time; it initially occurs through a microalbuminuria (an amount of albumin in the urine comprised between 30 and 300 mg/l) which slowly develops into macroalbuminuria indicating a manifest nephropathy (an amount of albumin in the urine exceeding 300 mg/l, up to reaching values of 3 g within 24 hours); hemodynamic, due to arterial hypertension. An alteration in the pressure mechanisms of the renal blood flow leads, over time, to a reduction of the renal filtering capacity; ischemic. Renal ischemia is the most frequent pathogenic event involved in acute renal disease and in the ensuing tubular necrosis, both in native and transplanted kidneys; toxic. Most of the clinically important drugs (cytotoxic agents, chemotherapy agents, nonsteroidal anti-inflammatory drugs, corticosteroid therapies, etc) and various chemical products (such as radiologic contrast media, solvents, etc) produce nephrotoxicities capable of very frequently causing inflammation at the renal parenchymal level and functional insufficiency both transitory and chronic. [0010] Even in veterinary medicine, renal diseases bound to develop into chronic renal disease constitute an important clinical category, representing the second cause of death in dogs, after diseases of tumour origin, and the first cause of death of the aged cats. From an etiologic point of view, the causes that determine the loss, progressive and irreversible, of the functionality of the nephrons in small animals were precisely classified in (Squires et al, 1998) in: Degenerative: chronic interstitial nephritis; renal infarction Autoimmune: Anti-GEM glomerulonephritis Metabolic: diabetes; hyperthyroidism (cats); hypercalcemia Neoplastic: renal lymphomas and carcinomas Idiopathic: amyloidosis; idiopathic glomerulonephritis Infective: bacterial pyelonephritis; Lyme nephropathy (Borreliosis) Immune-mediated: immune-complex glomerulonephritis Toxic: nephrotoxic drugs (e.g. cisplatin, aminoglycosides, NSAIDs) Traumatic: rupture of bladder and urethra. [0020] In any case, regardless of the etiology, in all acquired renal diseases, both in humans and animals, there is an activation of the inflammatory processes primarily aimed at countering the harmful events but which may become the cause of renal glomerulosclerosis and of tubulointerstitial fibrosis capable of determining the development of chronic renal disease up to the pre-End stage (pre-End Stage Renal Disease) wherein most of the nephrons are destroyed. One of the two main objectives of nephrology is, first and foremost, that of understanding the mechanism which regulates the passage from an acute renal damage to the chronic fibrotic renal disease given that, once the fibrogenesis has started it might be very difficult, currently, to intervene on the fibrotic process; in any case, the objective of stopping or at least slowing the progression of the chronic renal disease remains extremely important considering that such disease also constitutes an important risk factor for cardiovascular diseases. Regarding this, currently there are several studies aimed at accurately understanding the most significant mechanisms of occurrence, with the aim of preventing the phenomena that determines the irreversibility of the disease. Among these phenomena, the most significant one is that which induces tubulointerstitial fibrosis considered the main cause of the chronic renal disease; fibrosis causes an excessive accumulation of extracellular type, mainly made up collagen, and it is usually accompanied by a progressive loss of renal function when the normal tissue is replaced by a cicatricial tissue. One of the most currently studied phenomena is constituted by processes of controlling the genesis of mio-fibroblasts and by the role played by these cells in the formation of the fibrotic cicatricial tissue. In particular such studies try to understand the reason why a reparative phenomenon usually provided for by the tissue, like the renal one, continuously subjected to an extensive amount of novae, may at one point determine an excessive increase of the extracellular matrix and thus a tubulointerstitial fibrosis. Particular attention is currently paid to the genesis of mio-fibroblasts both starting from tubular-epithelial cells and from endothelial cells through a process of phenotypic transformation from epithelial to mesenchymal, potently stimulated by the TGF-1β (Transforming Growth Factor). Actually, the TGF-1βexpression constantly increases in the renal tubular epithelium during an active process of fibrogenesis. In animal models of renal damage, the dose in the renal tubular epithelium of the TGF-1β is considered an interesting indication of the state of activation of fibrogenesis and, hence the state of functional alteration induced by the renal disease. [0021] Regardless of the extensive new information regarding the pathogenic mechanisms involved in the development of renal diseases, satisfactory therapeutic solutions for controlling these conditions are yet to be discovered. [0022] Palmitoylethanolamide (PEA) is the parent of a family of N-acyl amides called Aliamides: a class of endogenous lipid molecules capable of normalizing the activity of immune cells through a local antagonist mechanism. The analgesic effects, instead, are related to a normalisation of the controlled release of trophic factors like NGF which, if present in excess in the tissues, make the neuronal structures hypersensitive and hyperexcitable, with the occurrence of hyperalgesia and allodynia. From a clinical point of view, the oral uptake of products containing PEA is capable of improving the neuropathic symptomotology related to the peripheral neuropathy also promoting the functional recovery of the motor conduction velocity. PEA, at experimental level, is also efficient in dysmetabolic neuropathies, in particular administration thereof to animals made diabetic with streptozotocin eliminates allodynia and induces a partial recovery of the body weight and an increase of the insulin blood levels. These animals also reveal low over-production of blood free radicals and the levels of NGF in the sciatic nerve. [0023] Analogously to the PEA, given N-acyl amides, generally formed from monoethanolamine and dicarboxylic fatty acids, saturated and unsaturated, per se non-physiologic but equally capable of forming, during catabolism, substances physiologically present in the organism of mammals, thus not determining accumulation and/or toxicity of any kind, proved capable of determining pharmacological effects similar to the parent PEA. SUMMARY OF THE INVENTION [0024] Now, we have surprisingly discovered that some molecules belonging to the class of the amides between an amino alcohol and a mono- or dicarboxylic acid are active in the treatment of renal diseases. In particular, it was observed that palmitoylethanolamide (PEA) and diethanolamide of fumaric acid, a monounsaturated dicarboxylic fatty acid normally present in the organism of mammals, revealed a considerable activity with respect to said diseases. [0025] Thus, a first object of the present invention is constituted by a mono- or diamide of a C12-C20 monocarboxylic acid, saturated or monounsaturated, or of a C4-C14 dicarboxylic acid, saturated or monounsaturated, respectively, with an amine selected from among monoethanolamine and serine, or mixtures thereof, for use in the treatment of renal diseases, in particular but not exclusively renal diseases caused by dysmetabolic diseases or by toxic agents. [0026] A further object of the present invention is represented by palmitoylethanolamide (PEA) for use in the treatment of renal diseases, wherein PEA is preferably in micronized form or in ultra-micronized form. [0027] A further object of the present invention is constituted by PEA for use in the treatment of renal diseases, wherein said PEA is administered orally. [0028] A further object of the present invention is constituted by diethanolamide of fumaric acid for use in the treatment of renal diseases, in aqueous solution. DETAILED DESCRIPTION OF THE INVENTION [0029] The present invention is based on the surprising discovery that the exogenous administration of a mono- or diamide of a C12-C20 monocarboxylic acid, saturated or monounsaturated, or of a C4-C14 dicarboxylic acid, saturated or monounsaturated, respectively, with an amine selected from among monoethanolamine and serine and in particular oral administration of Palmitoylethanolamide preferably in micronized form (PEAm) or in ultra-micronized form (PEAum) and/or of diethanolamide of fumaric acid, administered preferably in solubilised form in suitable aqueous media, is capable of substantially improving the renal function in a mammal affected by the renal disease, with particular reference to diabetic nephropathy and nephropathy from antitumor agents. The present inventors also discovered that the improvement of the renal function is associated to a lower expression of the TGF-1β considered a considerable indication of the fibrogenesis in progress. The improvement of the renal function is also confirmed in patients affected by inflammatory nephropathy and diabetic nephropathy. [0030] In an embodiment of the invention, said C12-C20 monocarboxylic acid, saturated or monounsaturated, is selected from among palmitic acid, stearic acid and oleic acid. [0031] In an embodiment of the invention, said C4-C14 dicarboxylic acid, saturated or monounsaturated, is selected from among fumaric acid, azelaic acid and trans-traumatic acid. [0032] Palmitoylethanolamide is a commercial product, which can be prepared through conventional methods, well known to a man skilled in the art, such as those that provide for the reaction between ethanolamine or serine, possibly in protected form, and said mono- or dicarboxylic acid in suitable conditions of condensation, which may also provide for the use of condensing agents. [0033] The term “PEA in micronized form” or “PEAm” is used to indicate palmitoylethanolamide in which at least 94% or at least 95% or about 96% of the particles has a dimension smaller than 10 microns and preferably at least 77% or at least 78% or about 80% of the particles has a dimension smaller than 6 microns. PEAm may be prepared according to the disclosure of the European patent n° EP 1 207 870 B1. [0034] The term “PEA in ultra-micronized form” or “PEAum” is used to indicate palmitoylethanolamide in which at least 97% or at least 98% or at least 99% or about 99.9% of the particles has dimensions smaller than 6 microns and preferably at least 57% or at least 58% or at least 59% or about 59.6% of the particles has dimensions smaller than 2 microns. PEAum may be prepared according to the disclosure of the patent application n° PCT/IT2009/000399. [0035] Diethanolamide of fumaric acid may be prepared by synthesis according to the disclosure of Example 10 of U.S. Pat. No. 5,618,842. [0036] Thus, the present invention regards a mono- or diamide of a C12-C20 monocarboxylic acid, saturated or monounsaturated, or of a C4-C14 dicarboxylic acid, saturated or monounsaturated, respectively, with an amine selected from among monoethanolamine and serine, or mixtures thereof, for use in the treatment of renal diseases, in particular but not exclusively renal diseases caused by dysmetabolic diseases or by toxic agents. [0037] In an embodiment said mono- or diamide of a C12-C20 monocarboxylic acid, saturated or monounsaturated, or of a C4-C14 dicarboxylic acid, saturated or monounsaturated is PEA or diethanolamide of fumaric acid. [0038] In an embodiment, PEA is used in micronized form (PEAm). [0039] In a different embodiment, PEA is used in ultra-micronized form (PEAum), alone or mixed with PEAm. [0040] In an embodiment, diethanolamide of fumaric acid is used in solubilised form in a suitable aqueous solvent. [0041] Pharmacological Activity of the Compounds of the Invention [0042] Occurrence of Renal Damage after Administration of Streptozootocin to Mice [0043] The model of streptozootocin in mice represents a classic and known model of hyperglycemia capable of inducing a progressive renal damage into the animal leading to the renal disease with clear alterations of the characteristic parameters. [0044] The model applied is as follows: male mice C57BL6/J were kept under standard conditions of care. Diabetes was induced into 8-weeks old mice and with an average weight of about 22 g by means of an intraperitoneal injection of streptozotocin in citrate buffer (55 mg/Kg of weight/day) for 5 consecutive days. The control animals were treated in the same conditions using the citrate buffer alone. [0045] Treatments were administered orally, by means of a tube, using both micronized Palmitoylethanolamide—PEAm (10.0 mg/Kg) suspended in a carrier and ultra-micronized palmitoylethanolamide PEAum (10.0 mg/Kg) suspended in a carrier; the results were compared with control animals treated with the carrier alone. A 0.5% carboxymethyl cellulose was used as a carrier. [0046] Diethanolamide of fumaric acid was administered in sterile aqueous saline solution by intraperitoneal injection (10.0 mg/Kg); the results were compared with the animals treated with sterile saline solution alone. [0047] Administration of the carrier and of the two different suspensions containing palmitoylethanolamide or of the injection solution containing diethanolamide of fumaric acid, were performed once per day starting from the day of the last administration of Streptozotocin. Prior to sacrifice, the blood was collected from the saphenous vein using a micro syringe to determining, through conventional methods, the levels of glycemia, glycated haemoglobin and creatinine of the serum. [0048] The evaluation of TGF-1β on the renal tissue was administered through the following method: [0000] small pieces of the renal cortex, carefully separated and weighed, were homogenised in Tris-HCl 10 mM buffer at 7.4 pH containing 2M of NaCl, 1 mM PMSF (phenylmethylsulfonyl fluoride, as a protease inhibitor), 1 mM EDTA and 0.01% of Tween 80. The samples were centrifuged at 19,000 rpm for 30 minutes and the supernatant was collected, measured and preserved at −80° C. The evaluation of the TGF-1β was made using the ELISA commercial kit (Quantikine Kit™, Res & Diagn Systems, Minneapolis, USA) and the value expressed in pg/mg of total proteins. The concentration of total proteins was measured using the Bio-Rad commercial test (Hercules, Calif., USA). [0049] The obtained results were gathered in Table 1. [0000] TABLE 1 Diabetic Diabetic animals Diabetic animals treated treated animals Diabetic by i.p. orally Diabetic treated with animals injection with Non- with the animals ultra treated by i.p. diethanolamide diabetic carrier treated with micronized injection with of fumaric acid animals alone micronized PEA - saline solubilised in Examined (10 (10 PEA - PEAm PEAum solution alone saline solution parameter animals) animals) (10 animals) (10 animals) (10 animals) (10 animals) Body weight (g) 27.82 ± 1.18  25.12 ± 1.10 26.52 ± 1.08 26.12 ± 1.21 24.43 ± 1.15 26.22 ± 1.02 Glycemia 122.2 ± 5.62  408.45 ± 33.12 386.12 ± 36.76 380.34 ± 34.16 406.32 ± 33.44 386.19 ± 33.98 (mg/dl) Glycated 4.89 ± 0.05 12.80 ± 0.44 11.32 ± 0.38 11.01 ± 0.18 13.41 ± 0.63 12.12 ± 0.26 haemoglobin % Kidney 6.65 ± 0.04  8.65 ± 0.85  7.85 ± 0.44  7.15 ± 0.38  9.00 ± 0.56  7.02 ± 0.46 weight/body weight Amount of 33.7 340.5 289.4 151.5 315.05 135.7 albumin (26.2-41.5) (182.2-630.3) (166.4-480.6) (71.3-283.8) (201.3-582.4) (94.6-171.4) excreted with urine (18 hrs prior to sacrifice) Concentration of 0.21 ± 0.01  1.11 ± 0.02  0.81 ± 0.01  0.44 ± 0.01  1.51 ± 0.08  0.51 ± 0.03 creatinine in the serum (mg/dl) Level of TGF-1β 7.5 ± 0.8 24.2 ± 5.8 15.0 ± 3.0 10.3 ± 2.5 25.3 ± 4.6 11.7 ± 3.2 (pg/mg) [0050] Occurrence of Renal Damage after Administration of Cisplatin to Mice [0051] Cisplatin, a known and widely used chemotherapy agent, notoriously produces a serious renal damage in 50% of the patients subjected to treatment. Experimentally an animal model is used in mice, in which Cisplatin induces serious nephrotoxicity with ensuing renal disease. The model applied is as follows: male mice C57BL6/J were kept under standard conditions of care. Nephrotoxicity was induced into 8-weeks old mice and with an average weight of about 23 g, by means of an intraperitoneal injection of Cisplatin dihydrochloride in saline solution (20 mg/Kg in one administration). The control animals were treated in the same conditions using the saline solution alone. The animals were sacrificed 72 hrs after treatment with Cisplatin. [0052] 6 treatments were administered orally, one each 12 hrs by means of a tube, using both micronized palmitoylethanolamide—PEAm (10.0 mg/Kg) suspended in a carrier and ultra-micronized palmitoylethanolamide—PEAum (10.0 mg/Kg) suspended in a carrier; the first treatment was carried out 12 hours prior to the administration of the Cisplatin. The results were compared with control animals treated with the carrier alone. A 0.5% carboxymethyl cellulose solution was used as the carrier. [0053] Diethanolamide of fumaric acid was administered in sterile aqueous saline solution by intraperitoneal injection (10.0 mg/Kg) with posology analogous to that of PEA; the results were compared with animals treated with sterile saline solution alone. [0054] Prior to sacrifice, the blood was collected from the saphenous vein using a micro syringe to measure, through conventional methods, the levels of creatinine of the serum. [0055] The level of TGF-1β on the renal tissue was measured through the following method: small pieces of the renal cortex, carefully separated and weighed, were homogenised in Tris-HCl 10 mM buffer at a 7.4 pH containing 2M of NaCl, 1 mM PMSF (phenylmethylsulfonyl fluoride, as a protease inhibitor), 1 mM EDTA and 0.01% of Tween 80. The samples were centrifuged at 19,000 rpm for 30 minutes and the supernatant was collected, measured and preserved at −80° C. The amount of the TGF-1β was measured using the ELISA commercial kit (Quantikine Kit™, Res & Diagn Systems, Minneapolis, USA) and the value expressed in pg/mg of total proteins. The concentration of total proteins was measured using the Bio-Rad commercial test (Hercules, Calif., USA). [0056] The obtained results were gathered in Table 2. [0000] TABLE 2 Animals Animals Animals with with with cisplatin Animals Cisplatin cisplatin treated by i.p. with Animals treated with treated by injection with Cisplatin with Cisplatin ultra i.p. injection diethanolamide Control treated with treated with micronized with saline of fumaric acid animals the carrier micronized PEA - solution solubilised in Examined (10 alone PEA - PEAm PEAum alone saline solution parameter animals) (10 animals) (10 animals) (10 animals) (10 animals) (10 animals) Body weight (g) 26.12 ± 1.11  23.10 ± 1.22  23.58 ± 1.13  24.55 ± 1.09  24.22 ± 1.45  24.15 ± 1.12  Kidney weight/body 6.44 ± 0.03 7.22 ± 0.80 7.85 ± 0.34 6.89 ± 0.42 8.15 ± 0.46 6.58 ± 0.26 weight Amount of albumin 37.4 363.75 270.90 175.9 351.57 181.4 excreted with urine (18 hrs (31.7-44.6) (282.8-735.9) (206.9-405.8) (91.7-260.8) (258.1-623.4) (96.3-225.6) prior to sacrifice) Concentration of 0.22 ± 0.01 1.26 ± 0.05 0.92 ± 0.03 0.48 ± 0.02 1.36 ± 0.02 0.83 ± 0.06 creatinine in the serum (mg/dl) Dose of TGF-1β 8.2 ± 0.7 25.3 ± 6.0  15.8 ± 3.5  9.4 ± 3.2 22.1 ± 4.3  9.1 ± 2.8 (pg/mg) [0057] Effect of Ultra-Micronized Palmitoylethanolamide PEAum in Nephropathic Patients [0058] Palmitoylethanolamide was administered to patients in form of tablets each containing 600 mg of active ingredient in ultra-micronized form; 2 tablets per day (one every 12 hours, after meals) were administered to patients for 60 consecutive days). [0059] Determination of the GRF (Glomerular Filtration Rate) by the creatinine endogenous marker was carried out according to the US National Renal Foundation criteria (K/DOQI clinical practice guidelines for chronic kidney disease, 2002), using the Cockcroft-Gault equation (Cockcroft D. W. et al, 1976). [0060] The results were indicated in Table 3. [0000] TABLE 3 GFR Glomerulal Filtration Rate (Creatinine Glycemia under fasting Clearance) abbr Age Gender Diagnosis T 0 T 60 T 0 T 60 Paz- S.G. 65 F Chronic Inflammatory N.D. N.D. 26.4 44.6 01 nephropathy Paz- S.C. 71 M Chronic Inflammatory N.D. N.D. 21.4 35.2 02 nephropathy Paz- F.S. 62 F Chronic Inflammatory N.D. N.D. 20.7 36.1 03 nephropathy Paz- M.R. 61 M Diabetic nephropathy 210 mg/dl 110 mg/dl 18.9 41.4 04 (Diabetes type 2) compensated compensated with 10 U. with 12 U. ready insulin retard insulin Paz- B.V. 77 F Diabetic nephropathy 240 mg/dl 230 mg/dl 22.4 35.6 05 (Diabetes type 2) compensated compensated with 10 U. with 10 U. ready insulin ready insulin Paz- N.C. 69 F Diabetic nephropathy 280 mg/dl 210 mg/dl 21.8 39.8 06 (Diabetes 2) compensated compensated with 10 U. with 10 U. ready insulin + ready insulin + 20 U. retard 20 U. retard insulin insulin [0061] The results indicated above clearly show that PEA, in particular when administered orally in micronized or ultra-micronized form, may be successfully used in the treatment of renal diseases in a mammal. Also diethanolamide of fumaric acid revealed to be active through intra-peritoneal injection. [0062] The compounds of the invention may thus be used, both for humans and veterinary purposes, in the treatment of renal diseases. [0063] Such diseases are preferably selected from among: Diabetic nephropathy Nephroangiosclerosis Pyelonephrite Polycystic kidney disease (polycystic kidney) Alport syndrome Lesch-Nyham syndrome Goodpasture's syndrome Lupus nephritis Immunoglobulin A nephropathy Tubular necrosis Glomerulonephritis Urethral stenosis Iatrogenous nephropathies (from NSAIDs, from cytotoxic drugs, from Lithium, from antibiotics, from Cyclosporine, etc) Nephropathies from therapeutic radiations Nephropathies of the aged. [0079] The compounds of the invention may thus be formulated for oral, buccal, parenteral, rectal or transdermal administration. [0080] PEA may be preferably formulated for oral administration. [0081] Diethanolamide of fumaric acid may be preferably formulated for oral or injection administration considering the high solubility of such synthetic molecule in water. [0082] For oral administration, the pharmaceutical compositions may be provided, for example, in form of tablets or capsules prepared conventionally with pharmaceutically acceptable excipients such as binding agents (for example pregelatinised maize starch, polyvinylpyrrolidone or hydroxypropyl methylcellulose); bulking agents (such as for example lactose, microcrystalline cellulose or calcium hydrogen phosphate); lubricants (for example magnesium stearate, talc or silica); disintegrants (for example potato starch or sodium starch glycolate); or inhibitor agents (for example lauryl sodium sulfate). The tablets may be coated by means well known in the art. The liquid preparations for oral administration may be, for example, in form of solutions, syrups or suspensions or they may be in form of lyophilised products to be reconstituted, prior to use, with water or other suitable carriers. Such liquid preparations may be prepared through conventional methods with pharmaceutically acceptable additives such as suspension agents (for example sorbitol syrup, cellulose derivatives or edible hydrogenated fats); emulsifying agents (for example lecithin or acacia); non-aqueous carriers (for example almond oil, oily esters, ethylic alcohol or fractionated vegetable oils); and preservatives (for example methyl- or propyl-p-hydroxybenzoates or sorbic acid). The preparation may also suitably contain aromas, colouring agents and sweeteners. [0083] The preparations for oral administration may be formulated suitably to allow the controlled release of the active ingredient. [0084] For buccal administration, the compositions may be in form of tablets formulated conventionally, suitable for absorption at the buccal mucosa level. Typical buccal formulations are tablets for sublingual administration. [0085] The compounds of the invention may be formulated for parenteral administration by injection. The formulations for the injection may be in form of one dose for example in a vial, with an added preservative. The compositions may be in such form as suspensions, solutions or emulsions in oily or aqueous carriers and they may contain formulary agents such as suspension, stabilising and/or dispersion agents. Alternatively, the active ingredient may be in form of powder to be reconstituted, prior to use, with a suitable carrier, for example with sterile water. [0086] Diethanolamide of fumaric acid may be easily formulated in sterile and non-pyrogenic aqueous solutions according to conventional literature of the pharmaceutical industry. [0087] According to the present invention, the compounds of the invention may also be formulated according to rectal compositions such as suppositories or retention enema, for example containing the basic components of common suppositories such as cocoa butter or other glycerides. [0088] In addition to the compositions described previously, the compounds of the invention may also be formulated as deposit preparations. Such long-term formulations may be administered by implantation (for example subcutaneous, transcutaneous or intramuscular) or by intramuscular injection. Thus, for example, the compounds of the invention may be formulated with appropriate polymer or hydrophobic materials (for example in form of an emulsion in a suitable oil) or ionic exchange resins. [0089] According to the present invention the dosage of a compound of the invention, or of mixtures thereof, proposed for administration to a man (with a body weight of about 70 Kg) ranges from 1 mg to 2 g and, preferably from 100 mg to 1 g of the active ingredient per dose unit. The dose unit may be administered, for example, from 1 to 4 times per day. The dosage shall be determined by the selected method of administration. It should be considered that frequent variations of the dose might be required depending on the age and the weight of the patient and also on the seriousness of the clinical condition to be treated. Lastly, the exact dose and method of administration shall be at the discretion of the doctor or veterinarian in question. [0090] The pharmaceutical compositions of the invention may be prepared using conventional methods, such as those described in Remington's Pharmaceutical Sciences Handbook, Mack Pub. Co., N.Y., USA, 17th edition, 1985. [0091] Following are non-exhaustive examples of pharmaceutical compositions according to the invention. Examples of Formulations Example 1 [0092] Each tablet contains: [0000] PEAm mg 300.00 Microcrystalline cellulose mg 78.47 Sodium croscarmellose mg 45.00 Polyvinylpyrrolidone mg 10.00 Stearate magnesium mg 4.00 Polysorbate 80 mg 2.00 Example 2 [0093] Each tablet contains: [0000] PEAum mg 300.00 Microcrystalline cellulose mg 78.47 Sodium croscarmellose mg 45.00 Polyvinylpyrrolidone mg 10.00 Stearate magnesium mg 4.00 Polysorbate 80 mg 2.00 Example 3 [0094] Each tablet contains: [0000] PEAum mg 600.00 Microcrystalline cellulose mg 156.94 Sodium croscarmellose mg 90.00 Polyvinylpyrrolidone mg 20.00 Stearate magnesium mg 8.00 Polysorbate 80 mg 4.00 Example 4 [0095] Each tablet contains: [0000] Diethanolamide of fumaric acid mg 400.00 Microcrystalline cellulose mg 100.00 Sodium croscarmellose mg 80.00 Polyvinylpyrrolidone mg 15.00 Stearate magnesium mg 7.00 Polysorbate 80 mg 6.00 Example 5 [0096] A 5 g dose of oral-dissolvable microgranules, for pediatric use, contains: [0000] PEAum mg 50.00 Non-cariogenic sugar mg 200.00 Pharmaceutically acceptable excipients q.s. to g 5.00 Example 6 [0097] A 5 ml dose of sterile suspension, for pediatric use, contains: [0000] PEAum mg 80.00 Carboxymethyl cellulose mg 25.00 Bi-distilled water q.s. to ml 5.00 Example 7 [0098] A 5 g dose of oral-dissolvable microgranules, contains: [0000] PEAum mg 600.00 Non-cariogenic sugar mg 200.00 Pharmaceutically acceptable excipients q.s. to g 5.00 Example 8 [0099] Each sterile single dose 5 ml two-layer container, contains: [0100] In the aqueous gel: [0000] Hyaluronic acid sodium salt mg 80.00 Bi-distilled water q.s. to ml 2.50 [0101] In the oily gel: [0000] PEAum mg 600.00 Monostearate glyceryl (Geleol) mg 40.00 vegetable oil q.s. to ml 2.50 Example 9 [0102] Each soft gelatin capsule, for veterinarian use (dog and cat), contains: [0000] PEAum mg 100.00 Pharmaceutically acceptable oily excipients mg 300.00 Example 10 [0103] A 2 ml glass vial contains: [0000] Diethanolamide of fumaric acid mg 100.00 Sterile saline solution q.s. to ml 2.0 Example 11 [0104] A 4 ml lyophilized glass vial contains: [0000] Diethanolamide of fumaric acid mg 200.00 Glycocol mg 85.00 [0105] A 4 ml solvent vial contains: [0000] Sterile saline solution ml 4.0 ml

A therapy for renal diseases, in particular renal diseases which develop in diabetic patients or patients who have been subjected to a treatment with an antitumor chemotherapy such as a platinum derivative and more generally cytotoxic drugs at renal level for treating of neoplastic diseases. More particularly, the present invention relates to palmitoylethanolamide and diethanolamide of fumaric acid for use in the treatment of renal diseases, in particular those caused by dysmetabolic diseases or by toxic or chemotherapy agents, such as platinum derivatives. Palmitoylethanolamide is used preferably in micronized or ultra-micronized form. Diethanolamide of fumaric acid is used preferably in aqueous solution.

BACKGROUND OF THE INVENTION THIS invention relates to a floodlight radar system for detecting and locating moving targets in three dimensions. When a radar system with the capability to rapidly detect and locate fast-moving targets in three dimensions anywhere in the search volume is required, a floodlight radar is an appropriate choice. Without scanning its beam (either mechanically or electronically), a floodlight radar transmitter continuously illuminates the full search volume by means of a single wide beam antenna. Detection and location of targets in three dimensions is accomplished by appropriately processing the signals received with multiple receive antennas. Floodlight radars, as described by W Wirth, Radar techniques using array antennas, IEE, 2001, pp. 419-447, have a long legacy. The first operational air-warning system, the Chain Home network built in Britain before the second world war, was a pulsed floodlight system described in British patent GB 593 017 of R Watt. The floodlight principle is also known under other names, such as Array Signal Processing (ASP)—see A. Rudge, K. Milne, A. Olver, and P. Knight, Eds., The Handbook of Antenna Design, Volume 2, Peter Peregrinus, London, U.K., 1983, pp. 330-456. In a floodlight radar, the transmitter “floods” the search volume with electromagnetic waves radiated from the transmit antenna. This is in contrast to a scanned radar, where an antenna directs a scanned pencil or fan beam to one or more small parts of the search volume at any one instant. The floodlight radar therefore simultaneously illuminates all targets in the scan volume at all times. The radiation patterns of the individual antennas of the multiple-channel receiver also cover the complete search volume. The antenna system is often referred to as a staring array. These characteristics of a floodlight radar are the keys to the rapid detection of fast-moving targets anywhere in the search volume. The receive antennas can either be arranged as a densely or sparsely packed phased array forming multiple simultaneous beams, as described by F. Athley, C. Engdahl, and P. Sunnergren, “On radar detection and direction finding using sparse arrays,” Aerospace and Electronic Systems, IEEE Transactions on, vol. 43, no. 4, pp. 1319-1333, October 2007, or as a sparsely packed interferometer array. The vertical and horizontal dimensions of the array determine the accuracy with which elevation and azimuth angles of arrival can be estimated. The densely packed array has the advantage that simultaneous beams covering the full search volume can be formed by means of ASP, with each beam providing a high antenna gain on receive. It is, however, a complex and costly system. A radar with a square array with dimensions of 5 wavelengths on a side covering a search volume of a quarter hemisphere will typically use a 64 channel receiver and a 64 channel signal processor. The sparsely packed array has the advantage that simultaneous beams covering the full search volume can be formed by means of ASP, with each beam providing a high antenna gain on receive, but has the disadvantage that grating lobes are also formed. Various techniques have been devised to identify and eliminate returns from targets in grating lobes as described in U.S. Pat. No. 7,692,575 of Nishimura. The sparse interferometer receive array does not form beams. It has the advantage of a lower hardware count for a given accuracy of location, but suffers the disadvantage of angular ambiguities, where targets at different locations can produce similar antenna responses. It requires special measures to resolve these ambiguities, one of which is to use overlapping high gain antennas, but this severely limits the search volume. The sparse array with wide-beam radiators has much lower directivity than the densely packed array. To overcome the disadvantage of low gain, the transmitter power must be increased with respect to that needed for a densely packed receive array. Conventional single-frequency direction-finder technology to resolve angular ambiguities is well-known, but requires at least five antennas arranged in two dimensions to resolve angular ambiguities in azimuth and elevation. See E. Jacobs and E. Ralston, “Ambiguity resolution in interferometry,” Aerospace and Electronic Systems, IEEE Transactions on, vol. AES-17, pp. 766-780, 1981. It is an object of the invention to provide a floodlight radar system that overcomes at least some of the above mentioned problems and is suitable for detecting and locating moving targets in three dimensions. SUMMARY OF THE INVENTION According to the invention there is provided a floodlight radar system including: a transmitter arranged to generate output waveforms at first and second centre frequencies; at least one transmit antenna configured to illuminate a search volume constantly at the first and second centre frequencies; a sparse array of receive antennas arranged in a common plane and configured to monitor the search volume constantly; a receive circuit arranged to extract target position information from return signals received by each antenna; and a signal processor circuit arranged to resolve ambiguities in the position information using a known relationship between calculated Doppler spectra, wavelengths and phase differences at the first and second frequencies, to calculate azimuth, elevation, range and velocity of a target identified in the search volume. The sparse array of receive antennas preferably comprises at least one set of three receive antennas. The sparse array of receive antennas may comprise two sets of three receive antennas, one set for each centre frequency. The three receive antennas may be arranged at the vertices of an equilateral triangle. The spacing between adjacent antennas may be indicated by the expression s=kλ, where s is the spacing, λ is the wavelength at the operating frequency of the antennas and k is a value larger than 1. Preferably, k has a value of approximately between 1 and 5. In one example embodiment, k may have a value of approximately 5. In another example embodiment, k may have a value of approximately 2.5. In yet a further example embodiment, k may have a value of 3. The transmitter may be arranged to produce a modulated continuous waveform or alternatively to produce a pulsed waveform. Preferably, the transmitter is arranged to produce a continuous wave waveform. The transmitter may be arranged to generate output waveforms at the first and second centre frequencies alternately. Instead, the transmitter may be arranged to generate output waveforms at the first and second centre frequencies simultaneously. In the first case, each receive antenna may have a single receive channel capable of processing return signals at one or both centre frequencies alternately. In the latter case, each receive antenna may have an associated pair of receive channels for the processing of return signals at the first and second centre frequencies simultaneously. Alternatively, when using separate receive arrays for each frequency, each receive antenna may have a single receive channel for the processing of return signals at either the first or second centre frequency. The signal processor is preferably arranged to sample the return signals from each antenna at each of the two frequencies in the time domain. In the case of a pulse modulated waveform, each sample, after pulse compression if required, represents a range bin. In the case of a continuous wave waveform, the signal processor preferably calculates the discrete Fourier spectrum of the signal, where each discrete component of the transform represents a range bin. The signal processor may calculate discrete Doppler spectra for each range bin from a large number of observations. The signal processor is preferably arranged to detect targets by comparing the Doppler spectra for each range bin to the noise in the spectra when no target is present. The signal processor may be arranged to accurately interpolate the range of the target by comparing amplitude returns from the target in adjacent range bins. The signal processor may be arranged to accurately interpolate the radial velocity of the target by comparing amplitude returns from the target in adjacent Doppler bins. Each detected target is preferably associated with a track according to its range and velocity information. The signal processor is preferably arranged to compare the phase returns of each detected target from each of the antennas. The respective phase differences are used to determine the angular location of each target in azimuth and elevation. The signal processor is preferably arranged to resolve angular ambiguities resulting from the wide antenna spacing by comparing the phase differences between measurements of the same target at the two centre frequencies. The signal processor may be arranged to use redundant information gained from the receiver channels to estimate and indicate the quality of the angular measurement. The signal processor may be arranged to distinguish between inbound, outbound and other ambiguous velocities by comparing the Doppler spectra of the target at the two centre frequencies. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing the configuration of a sparse receive array, consisting of three widely spaced antennas, forming part of a floodlight radar system according to the invention; FIG. 2 is a partially cut away pictorial view of a typical antenna element used in the receive array and as a transmit antenna, which will provide coverage over more than an eighth of a hemisphere; FIG. 3 is a schematic diagram which illustrates the principle by which the Direction of Arrival of an incoming plane wave signal is determined along one axis of the antenna array; FIG. 4 is a schematic diagram showing how the target position is arrived at by using a DOA measurement along one axis of the antenna array; FIG. 5 is a schematic diagram showing how the 3D target position is arrived at by using DOA measurements along the three axes of the antenna array; FIG. 6 is a block diagram of a transceiver for a floodlight radar system according to an example embodiment of the invention, with multiplexed receive channels; FIG. 7 is a block diagram of a transceiver for a floodlight radar system according to an example embodiment of the invention, with simultaneous receive channels; FIG. 8 is a block diagram of a transceiver for a floodlight radar system according to an example embodiment of the invention, with separate receive antenna arrays having separate receive channels; FIG. 9 is a block diagram of a signal processor used in conjunction with the transceiver of FIGS. 7 and 8 ; FIG. 10 is a simplified diagrammatic illustration of an example embodiment of a radar system according to the invention deployed as a radar that determines the trajectories of targets such as cricket balls and projectiles; FIG. 11 is a simplified diagrammatic illustration of an example embodiment of a radar system according to the invention deployed as a gap-filler radar in a wind-farm; and FIG. 12 is a simplified diagrammatic illustration of an example embodiment of a radar system according to the invention deployed as a sensor for an armoured vehicle protection system. DESCRIPTION OF EMBODIMENTS The system described herein is a unique floodlight radar with a sparse interferometer receive array using only three receive antennas, that resolves target angular ambiguities in a spherical coordinate system by means of frequency diversity. The receive antennas are arranged in two dimensions and ambiguity resolution is typically accomplished by taking measurements at two frequencies. The radar also assesses the quality of its measurements and identifies suspect measurements that were degraded due to noise or propagation anomalies such as multipath. The Receive Array and the Principle of Ambiguity Resolution The receive array of the radar system described herein is at the core of the system concept and is shown schematically in FIG. 1 , where a receive antenna 10 , 12 , 14 is placed at each vertex or corner of an equilateral triangle. This is not the only possible arrangement of the antennas. They could, for instance, also be arranged at the vertices or corners of a right-angled triangle or, in general, at the corners of an irregular triangle. The antennas are spaced several wavelengths apart, at a spacing s=kλ. Preferably, k is greater than 1 and most preferably falls in the range 4 to 7. A typical spacing for the equilateral arrangement is five wavelengths, or s=5λ (i.e. a value of k of approximately 5). The three receive antennas for each centre frequency are preferably identical, a typical implementation of one such antenna being shown in FIG. 2 . The illustrated antenna has a central circular waveguide feed 16 and a dielectric lens 18 , with a peripheral isolation choke 20 . A fourth similar antenna is used as a transmit antenna. This could either be a separate antenna or one of the receive antennas could double for this purpose. An array as shown in FIG. 1 can be used to determine the direction of arrival (DOA) of an incoming signal, according to the principle shown in FIG. 3 . Let a plane wave varying sinusoidally with time and emanating from a source far away from the antenna array impinge upon the array from a direction θ with respect to a line perpendicular to the line connecting the phase centres of two identical antennas. Depending on the magnitude of the angle θ, there will be a path length difference kλsin(θ) from the source to the 2 nd antenna 12 with respect to the path length from the source to the 1 st antenna 10 . The instantaneous phase angle of the electric field vector is a function of time and distance travelled according to the equation E ⁡ ( t , ς ) = E ⁡ ( ς ) ⁢ cos ⁡ ( ϕ ⁡ ( t , ζ ) ) = E ⁡ ( ζ ) ⁢ cos ⁡ ( ω ⁢ ⁢ t - 2 ⁢ π ⁢ λ ⁢ ζ + ϕ 0 ) . In this equation, ζ is the distance travelled in the direction of propagation, E(ζ) is the peak magnitude of the electrical field vector, ω=2πf is the frequency in radians/second for a wave oscillating with a frequency f Hz, λ is the wavelength of the wave, given by λ = 2 ⁢ π ⁢ ⁢ c ω = c f where c is the velocity of propagation and φ 0 is the instantaneous phase angle at time t=0 and position ζ=0. There will consequently at any given instant be a difference in the phase angles of the signals emanating from the two antennas, given by Δ ⁢ ⁢ ϕ u ⁢ ⁢ 12 = ϕ 1 ⁡ ( t , ζ 1 ) - ϕ 2 ⁡ ( t , ζ 2 ) = 2 ⁢ π λ ⁢ ( ζ 2 - ζ 1 ) = 2 ⁢ k ⁢ ⁢ π ⁢ ⁢ sin ⁡ ( θ ) , where subscript 1 refers to the 1 st antenna 10 and subscript 2 refers to the 2 nd antenna 12 . It is convenient to substitute a new variable u for the function sin(θ), so that Δφ u12 =2kπu. The variable u has a range [−1≦u≦1]. All angles are measured modulo 2π, in the range [−π<φ≦π]. Therefore, if k>0.5, Δφ u12 can fall outside the measurable range and wraps back to a measured phase difference Δφ m12 =Δφ u12 −2 πp, where p is, in general, an unknown positive or negative integer. As a consequence, the determination of u and eventually θ from a measurement Δφ m12 is ambiguous. For the sparse array considered here, with k of the order of 5, Δφ m12 can wrap up to four times when [ - π 2 < θ < π 2 ] . The true phase difference must therefore be written as Δφ u12 =2 kπu=Δφ m12 +2 πp, where p is unknown. For k=5, p takes on integer values in the range [−2≦p≦2]. For an unambiguous determination of the arrival angle θ, some means must be found to determine p. In the radar system described here, p is determined by repeating the phase difference measurement at a second frequency. See M. Skolnik, “Resolution of angular ambiguities in radar array antennas with widely-spaced elements and grating lobes,” Antennas and Propagation, IRE Transactions on, vol. 10, no. 3, pp. 351-352, May 1962. The author describes the use of measurements at two frequencies to identify and eliminate echoes from targets in grating lobes of a scanning radar with a sparse array antenna. This in effect changes the electrical antenna spacing. With subscripts a and b referring to frequency a and frequency b, we have k a λ a =k b λ b =s Δφ u12a =2 πk a u=Δφ m12a +2 πp a Δφ u12b =2 πk b u=Δφ m12b +2 πp b Taking the difference of the phase angles yields Δ ⁢ ⁢ ϕ 12 ab = Δ ⁢ ⁢ ϕ u ⁢ ⁢ 12 a - Δ ⁢ ⁢ ϕ u ⁢ ⁢ 12 b = 2 ⁢ π ⁡ ( k a - k b ) ⁢ u , ⁢ where k a - k b = s λ a - s λ b = s c ⁢ ( f a - f b ) . We note that if | k a −k b |≦½, then [−π≦Δφ 12ab ≦π]. Consequently, if | k a −k b |≦½, φ 12 ab cannot wrap and a determination of u from Δφ 12 ab is unambiguous. (Note that, if the coverage of the antenna is smaller than [ - π 2 < θ < π 2 ] , the range of u decreases and the spacing between the antennas can be increased without introducing ambiguity.) In practice, the determination of u from Δφ 12 ab is not very accurate and also quite noisy. Our approach is therefore to determine a coarse estimate of u from Δφ u12 ab , and then to use this coarse estimate to find an estimate for the correct values of integers p a and p b . We then use these estimates of p a and p b to find a more accurate value of u using Δφ 12 a and Δφ 12 b . Effects such as noise, multipath and interference generally affect the phase angles of the two frequencies in ways that do not follow the defined relationship. This results in the values of u calculated with the two frequencies to differ. When an incorrect value is found for p a and/or p b , the difference between the two values of u can become large. This difference is used as the axis angle input for the confidence parameter that is described below. Note that this difference is calculated for each of the three axes. 3D Target Location We determine the 3-dimensional target location with reference to a coordinate system centred on the antenna array with the x-y axes in the plane of the array, as shown in FIG. 1 . The z-axis is perpendicular to the array in the direction of radiation. To locate a target in three dimensions with the array, first consider the determination of target position from a measurement taken from two antennas. The line connecting the antennas, called an array axis, is inclined at an angle γ to the x axis. The target is detected at range R with its DOA θ determined with respect to the plane perpendicular to the array axis, as shown in FIG. 4 . The target must lie on a circle on the surface of the right circular cone with aperture (π−2θ) with its apex at the centre of the array, at a distance R from the apex. We note that the target must also lie somewhere on the hemisphere with radius R. The intersection of the cone and hemisphere is a semicircle, the plane of which is perpendicular to the array axis and therefore also to the plane of the array. The semicircle intersects the plane of the array at the points (x 1 , y 1 ) and (x 2 , y 2 ), given by x 1 = ⁢ R ⁢ ⁢ cos ⁡ ( γ + θ - π 2 ) = ⁢ R ⁢ ⁢ sin ⁡ ( γ + θ ) y 1 = - R ⁢ ⁢ cos ⁡ ( γ + θ ) ⁢ ⁢ x 2 = - R ⁢ ⁢ sin ⁡ ( γ - θ ) ⁢ ⁢ y 2 = R ⁢ ⁢ cos ⁡ ( γ - θ ) . Solving for the equation of the line connecting (x 1 , y 1 ) and (x 2 , y 2 ), we find that the (x,y) coordinates of the target must lie on the line x = - tan ⁡ ( γ ) ⁢ y + R ⁢ ⁢ sin ⁡ ( θ ) cos ⁡ ( γ ) Two further estimates of location lines in the x-y plane are obtained from measurements along the other two axes of the array, as shown in FIG. 5 . For the specific antenna arrangement of FIG. 1 , where the antennas are placed at the corners of an equilateral triangle, we have the following equations for the three location lines given by the DOA angle θ 12 determined from the signal phase differences from the 1 st antenna 10 with respect to the 2 nd antenna 12 (γ=60°), θ 32 from the 3 rd antenna 14 with respect to the 2 nd antenna 12 (γ=0) and θ 13 from the 1 st antenna 10 with respect to the 3 rd antenna 14 (γ=120°): x=− √{square root over (3)} y+ 2 R sin(θ 12 ) x=R sin(θ 32 ) x= √{square root over (3)} y+ 2 R sin(θ 13 ). Three equations (as represented by the three location lines) are therefore available to solve only two unknowns (x and y), resulting in an overdetermined system. Under ideal conditions, the three lines cross in a single point. In practice, factors such as interference, multipath or noise can cause the system to become inconsistent and the lines then define a triangular area 22 , called a cocked hat, within which the target is assumed to be located. After solving for the three corners of the cocked hat, various possibilities must be evaluated. For instance, two of the lines may be correctly resolved, in which case one of the corners of the cocked hat is the best estimate of the position. The history of previous measurements (i.e. an established track) may be used to identify such a solution. If no other information is available to identify the best solution, the centroid of the triangle may be used as the best estimate of target position. The centroid lies at x c = 2 ⁢ ⁢ sin ⁡ ( θ 32 ) + sin ⁡ ( θ 12 ) - sin ⁡ ( θ 13 ) 3 ⁢ R y c = sin ⁡ ( θ 13 ) + sin ⁡ ( θ 12 ) 3 ⁢ ⁢ R . The solution for the centroid in terms of the variables u ij =sin(θ ij ) is given by x c = 2 ⁢ u 32 + u 12 - u 13 3 ⁢ R y c = u 13 + u 12 3 ⁢ R . With the (x, y) coordinates of the target determined, the z-coordinate is found from the relationship between the coordinate positions and the range, R 2 =x 2 +y 2 +z 2 , as z c =√{square root over ( R 2 −x c 2 −y c 2 )} The size of the cocked hat is a useful indicator of the reliability of the measurement and serves as the 3D angle input to the confidence parameter, described in the next section. The side of the cocked hat normalized to unity range is given by s = 2 3 ⁢  u 13 + u 32 - u 12  . The proportionality constant is not of importance, so that the parameter Rel_size=| u 13 +u 32 −u 12 | is used as an indicator of the size of the cocked hat. The Confidence Parameter The quantity u for a specific antenna axis is calculated from the phase difference for each frequency (e.g. Δφ 12a and Δφ 12b ), using the estimates for p a and p b . u a = Δ ⁢ ⁢ ϕ m ⁢ ⁢ 12 ⁢ a 2 ⁢ π ⁢ ⁢ k a + p a k a u b = Δ ⁢ ⁢ ϕ m ⁢ ⁢ 12 ⁢ b 2 ⁢ π ⁢ ⁢ k b + p b k b Small errors ε 12a and ε 12b in the phase difference measurements Δφ m12a and Δφ m12b will cause errors ɛ 12 ⁢ a 2 ⁢ π ⁢ ⁢ k a ⁢ ⁢ and ⁢ ⁢ ɛ 12 ⁢ b 2 ⁢ π ⁢ ⁢ k b ⁢ in the calculated values for u. The resultant error in u with typical values for k a and k b is generally within the accuracy limits of the system. A phase difference error large enough to cause the integers (p a or p b ) to be incorrectly resolved will, however, result in a discrete and significant error in the calculated value of u. This allows for binary indicators to be set up for monitoring the reliability of the angle extraction. The confidence calculation is based on four inputs: three axis angle inputs (differences in calculated values of u) as well as a 3D angle input given by the relative size of the cocked hat. Four binary indicator outputs can then be calculated: the three axis angle confidence indicators and the 3D angle confidence indicator. These four outputs can then be suitably combined to arrive at a single confidence parameter. Three Axis Angle Confidence Indicators The large, discrete difference between u a and u b can be used as a binary indication of whether an integer p a or p b has been estimated incorrectly. This indicator is available for each of the three antenna axes. It may occasionally happen that the phase difference errors on the two frequencies are such that u a and u b remain in agreement, e.g. when both p a and p b are estimated incorrectly, in which case an error will not be indicated. Single 3D Angle Confidence Indicator An incorrect estimation of p a or p b that causes u to be incorrectly calculated on an axis will shift the location line associated with that axes. This will increase the size of the cocked hat by a discrete amount, which can again be used as a binary indication of a suspect angle extraction. Usage The confidence indicators are used as inputs to the tracking algorithm and are also made available to the user of the system. Example of a System Embodiment The Transceiver Three block diagrams showing the implementation of an FMCW radar transceiver of a rapid location 3D radar system according to an example embodiment of the present invention are shown in FIGS. 6 , 7 and 8 . The principle of ambiguity resolution is equally applicable to a coherent pulsed radar system implementation. FIG. 6 shows a multiplexed system with low hardware count, where the waveform generator generates alternating bursts at the frequencies f 1 and f 2 . FIG. 7 shows an implementation with a six channel receiver and a shared receive antenna array, where the bursts at frequencies f 1 and f 2 are transmitted simultaneously. FIG. 8 shows an implementation with a six channel receiver fed by six receive antennas where the bursts at frequencies f 1 and f 2 are transmitted simultaneously. The implementations in FIGS. 7 and 8 are the preferred implementations if rapid detection of the target is a high priority. The less expensive implementation in FIG. 6 is suitable for applications where the rapid detection of a target is not such a high priority. The implementation in FIG. 8 has the advantage that the receive antennas may be separately optimised for each frequency, and that the losses associated with the diplexers are eliminated. The principle of operation of the three systems is the same. With reference to FIG. 7 , a waveform generator 24 generates two chirped up sweep FMCW signals simultaneously, starting at 9.1 and 10.1 GHz respectively, each with a sweep rate of 3.125 THz/s and a sweep repetition frequency of 49.135 kHz. The effective sweep bandwidth is 51.2 MHz and the range resolution of the radar is 2.93 m. The signals are amplified to a level of 1 W by means of power amplifiers 26 and 28 . Two directional couplers 30 and 32 tap off local oscillator signals for the IQ down-converters in the receiver channels. The signals from the two power amplifiers are combined in a diplexer 34 and fed to the transmit antenna 36 , which is a 17 dB gain pyramidal horn with a horizontal and vertical 3 dB beamwidths of 25°. The echoes from the target are picked up by a receive array which consists of three horn antennas 38 , 40 and 42 which are identical to the transmit antenna 36 , arranged on the corners of an equilateral triangle with a horizontal base, and with an inter-antenna spacing of 192 mm, or 6.5λ at 10.1 GHz. The array can be tilted with its plane out of the vertical. The signals from the antennas are fed through PIN diode limiters 44 to the receivers where the two channels are separated with a diplexer filter 46 . The signal at f 1 is fed to a low noise amplifier 48 and IQ down-converter 52 . The LO signal for the down-converter is a sample of the transmit signal for that channel, so that the intermediate frequency output signal from the down-converter is around zero frequency and known as a zero-frequency IF (ZIF). The IF signal is amplified by a low noise amplifier 56 and passed through a polyphase filter 60 that selects the lower sideband. A sensitivity-frequency control (SFC) and amplifier-filter circuit 64 , that shapes the frequency response of the receive channel so as to reduce the sensitivity of the radar for close-by targets which produce low-frequency responses, amplifies the signal and low-pass filters it to band-limit the signal to less than 7.8 MHz. Finally, the band-limited is passed through an analogue to digital converter (ADC) 68 and the resulting digital signal is fed to the signal processor (see FIG. 9 ). The f 2 signal from the diplexer is fed through an identical receiver channel 50 , 54 , 58 , 62 , 66 and 70 but fed with an LO signal at f 2 . A further two identical pairs of receiver channels down-convert the signals from the antennas 40 and 42 to produce six IF output signals in total. The Signal Processor A functional block diagram of the signal processor is shown in FIG. 9 . The six IF signals from the three receiver channels are fed in at the top of the block diagram, to respective ADCs 72 . 1 , 72 . 2 , 72 . 3 and 74 . 1 , 74 . 2 , 74 . 3 where they are sampled. (The same ADCs are also shown in FIGS. 7 and 8 ). The respective samples are fed to an FFT process 76 . 1 , 76 . 2 , 76 . 3 and 78 . 1 , 78 . 2 , 78 . 3 to produce the 256 sample range FFT. The positive 128 bins of the range FFTs are fed to a second FFT process 80 . 1 , 80 . 2 , 80 . 3 and 82 . 1 , 82 . 2 , 82 . 3 to produce Doppler spectra for each of the 128 range bins and for each of the six channels. The output of these processes are a set of range-Doppler maps of complex numbers, of which the phase and magnitude values are calculated at 84 . 1 , 84 . 2 , 84 . 3 and 86 . 1 , 86 . 2 and 86 . 3 . Detections are registered separately for each of the two frequencies by summing the magnitudes of the three range-Doppler maps for each antenna at each frequency, at 88 and 90 , and taking the logarithm of the result at 92 and 94 . This signal is then passed through a slow and a fast integrator 96 , 98 and 100 , 102 after which the slow signal is subtracted from the fast signal using a comparator 104 and 106 and passed to a threshold detector 108 and 110 , and a binary integrator 112 , to make an m out of n detection decision. A specific target will produce different Doppler spectra at the two frequencies. The relationship between the Doppler spectra at the two frequencies is known and is consequently used to resolve velocity ambiguities and to distinguish between inbound and outbound targets. The information is then passed to a track manager 114 which rejects sporadic detections and establishes tracks on detections with compatible velocity and range sequences. Once a track is established, the phase differences between signals from the different antennas for that target are extracted at 116 from the range-Doppler maps for frequencies f 1 and f 2 , and passed through smoothing filters to the ambiguity resolver which identifies the correct angle of arrival. Finally, azimuth and elevation angles, range, velocity, time-stamp, signal to clutter ratio and confidence parameter output is produced for each tracked target. TYPICAL APPLICATIONS The radar system described here has many potential applications. A first application is as a short range radar that can accurately measure the trajectories of objects such as cricket balls, projectiles, missiles and rockets, as shown in FIG. 10 . The radar is located in a compact housing 118 which contains the antennas 36 , 38 , 40 and 42 and the associated electronics. The radar can conveniently be supported on a tripod 120 or other portable support structure, or could be mounted to a pole or other fixed structure. Since the direction in which a cricket ball is going to be hit is unknown, the search volume can be set to include the full volume above a cricket field where a ball is likely to travel. The radar can locate the cricket ball within a few milliseconds after being hit. The radar location can then be used to direct a video camera at the ball for live TV coverage of the event, and also accurately report the speed with which the ball is travelling and also predict the point where the ball will hit the ground. A similar application would be to track projectiles at a test firing range or to track and determine the origin of small arms fire during peace-keeping operations. With its ability to accurately determine the location of objects in space, a radar according to this invention is also excellently suited as a radar sensor to enable precision guidance of manned and unmanned aerial vehicles during take-off and landing. Another application is as a “gap-filler” radar, e.g. in a wind-farm, as shown in FIG. 11 . Wind-farms present a hazard to air traffic control, as standard ATC radars cannot detect aircraft overflying wind farms reliably because of the limited observation time each time the antenna scans across the wind farm. The gap-filler radar, on the other hand, observes the turbine blades continuously and can distinguish between aircraft targets and turbine blades. In FIG. 11 , a wind farm 122 has several wind turbines 124 . A gap filler radar 126 according to the invention is located centrally in the wind farm, facing upwardly. The cylindrical coverage diagram of the radar is indicated by the numeral 128 . The gap filler radar detects and reports aircraft overflying the wind farm to the ATC radar which is adversely affected by the wind-farm. With its ability to rapidly detect and locate an incoming target, a radar according to the invention is excellently suited as a radar sensor for an armoured vehicle protection system, as shown in FIG. 12 . The radar sensor unit 130 is mounted on the side of an armoured vehicle 132 . On detection of an incoming projectile 134 , such as a rocket propelled grenade, the location and trajectory of the projectile is sent to a countermeasures system 136 which directs a counter-projectile at the incoming grenade to destroy it before it reaches the armoured vehicle. In summary, the above described floodlight radar system is able rapidly to detect and locate multiple fast moving targets in three dimensions. The radar continuously surveys a quarter hemisphere of space, and 3D target position is determined by a sparse interferometer array consisting of only three receive antennas arranged in two dimensions. Once a track is established, target angular ambiguities associated with sparse direction finding arrays are resolved by employing a frequency diversity waveform scheme. The radar generates a confidence parameter which flags unreliable measurements when multipath propagation or noise degrades the accuracy of a measurement.

A floodlight radar system includes a transmitter arranged to generate output waveforms at first and second centre frequencies, and at least one transmit antenna configured to illuminate a search volume constantly at the first and second centre frequencies. A sparse array of receive antennas is arranged in a common plane and configured to monitor the search volume constantly. The system includes a receive circuit arranged to extract target position information from return signals received by each antenna, and a signal processor circuit which is arranged to resolve ambiguity in the position information using a known relationship between calculated Doppler spectra, wavelengths and phase differences at the first and second frequencies, to calculate azimuth, elevation, range and velocity of a target identified in the search volume. The system is able to rapidly detect and locate multiple fast moving targets in three dimensions.

FIELD OF THE INVENTION The present invention is directed generally to traffic simulation in telecommunications networks and specifically to traffic simulation in asynchronous transfer mode networks. BACKGROUND OF THE INVENTION The current public switched telephone network (PSTN) was implemented as a highly reliable, robust, and efficient system for transporting voice traffic. The PSTN has now been burdened with additional types of traffic for which the PSTN was not designed to transport (e.g., Internet, file transfer, video, fax, etc.). The current narrowband synchronous transfer mode (STM) telephony system will have to be replaced by or evolve into a broadband network to preserve the integrity of the system and accommodate the new services. The asynchronous transfer mode (ATM) protocol has been selected as the core switching protocol for emerging broadband networks. ATM is an elegant protocol that has the desirable ability to multiplex voice, video, and data and to transmit information on the same communications channel at very high speeds. As used herein, ATM refers to a connection-oriented protocol in which bandwidth is allocated when the originating end user requests a connection. This allows ATM to efficiently support a network's aggregate demand by allocating bandwidth on demand based on immediate user need. Problems have been encountered in modeling traffic on an ATM network, which has complicated the design and analysis of ATM networks. For a network to be properly sized and provisioned, the design engineer must thoroughly understand the traffic load and the behavior of that traffic load over time. Traditionally, STM networks were based on the Poisson model. Random number generators were used to produce streams of numbers, representative of real network interarrival times, and which are based on the Poisson model. However, this model is unable to accurately characterize the “bursty” nature of ATM network traffic. Burstiness is present in a traffic process if the arrival points appear to form visual clusters; that is, the packets have runs of several short interarrival times (i.e., the time interval between the receipt of successive packets at a specified destination from a specific source) followed by a relatively long one. As will be appreciated, voice and video packets in ATM networks are typically given a higher priority than data packets in routing or switching the packets for processing. Accordingly, data packets can have significantly longer packet interarrival times than voice or video packets. Other models have been considered in modeling ATM traffic using random number generators, including the Markov Modulated model, the Transform Expand Sample model, the Autoregressive model, the Fluid model, and the Self-similar model. Although these models have been found to have varying degrees of success for modeling Ethernet traffic (which, like ATM networks, uses a packet-based protocol), they have been largely unsuccessful in characterizing the bursty nature of ATM traffic. The failure of these models is in part due to the differences between ATM networks and other type of packet networks. For example, ATM is a connection-oriented protocol with a fixed length packet size. This contrasts with Ethernet which is a connectionless protocol with variable length packet size. Variable packet sizes give rise to a Gaussian (normal) or exponential probilistic distribution of packet interarrival times. SUMMARY OF THE INVENTION These and other needs are addressed by the methods and systems of the present invention. The present invention is premised on the recognitions (a) that interarrival times of packets in ATM networks can have a lognormal probabilistic distribution; (b) that delayed packets on an ATM network can follow a normal probabilistic distribution; and (c) that packet interarrival times in an ATM network corresponding to data packets alone or to data packets and voice and/or video packets typically have bimodal probabilistic distributions. In one configuration, a probabilistic distribution(s) is defined by a normal or self-similar (Gaussian) model and the other probabilistic distribution(s) is defined by a lognormal model. As used herein, a “network” refers to an architecture having two or more computers (e.g., each of which includes a processor and memory) connected by one or more communication paths (e.g., a local area network (LAN) or wide area network (WAN)). In a typical ATM network, short packet interarrival times (i.e., less than a selected value) define a lognormal probabilistic distribution while long packet interarrival times (i.e., more than a selected value) define a normal probabilistic distribution. In a first embodiment of the present invention, a method for modeling or predicting the performance of (or simulating the traffic in) an ATM network is provided. The ATM network will transport or has transported a stream of packets. The method includes the step of generating (e.g., randomly or psuedorandomly) an at least substantially lognormally distributed set of packet interarrival times corresponding to the plurality of packets. By using lognormal number generators, the methodology of the present invention accurately considers the effect of ATM switch characteristics on traffic behavior. The simulated traffic generated by the algorithm compares closely with traffic on an actual ATM network. For this reason, the algorithm has applications in the areas of ATM switch design, ATM traffic simulation tools, and ATM network design and optimization (particularly the derivation of trunking tables, which are used to size and provision switch trunks). In one configuration, the packet stream also includes a second plurality of packets having normally distributed packet interarrival times. In that event, the method would further include generating (e.g., randomly or pseudorandomly) a normally distributed set of packet interarrival times. In another configuration, the method further includes the steps of (i) multiplying (a) a percentage of the packet stream that corresponds to the plurality of packets and (b) the number of packets in the packet stream to provide the number of packets in the plurality of packets and (ii) multiplying (a) a percentage of the packet stream that corresponds to the second plurality of packets and (b) the number of packets in the packet stream to provide the number of packets in the second plurality of packets. This is a typical step used in modeling an existing or planned ATM network. The total number of packets in the packet stream during a selected time interval can be selected using any technique for characterizing traffic in a communications network, such as busy hour, busy day, busy month, peak call rate, committed burst size, and the like. The number generators can be any algorithm providing output defined by the desired probabilistic distribution (e.g., normal or lognormal probabilistic distributions). In one configuration, the number of generators are random or pseudorandom number generators. In one configuration, the number generators require input such as the number of packets in the plurality of packets (or sample size or vector length) and a mean and a variance of a lognormal distribution characterizing (or believed to characterize) packet interarrival times of the plurality of packets (for the lognormal random number generator) or the number of packets in the second plurality of packets (or second sample size) and a mean and a variance of a normal distribution characterizing (or believed to characterize) packet interarrival times of the packets in the second plurality of packets (for the normal random number generator). As will be appreciated, other techniques may be used to generate lognormal or normal distributions of packet interarrival times including artificially constructed ATM packets (comprising a series of ones and zeros, 58 bytes in length) which have lognormal and normal time interval distributions between packets. In another configuration, the second plurality of packets has a bimodal distribution. This is a common occurrence when voice and/or video packets arrive at different times such that the data packets have a wide range of packet interarrival times. In this configuration, (a) a lognormal fraction of packets in the second plurality of packets having at least substantially lognormally distributed packet interarrival times and (b) a normal fraction of packets in the second plurality of packets having at least substantially normally distributed packet interarrival times are determined. The generating step for the packets in the second plurality of packets is applied to the number of packets in the normal fraction of packets. For the number of packets in the lognormal fraction of packets, the step of generating an at least substantially lognormally distributed set of packet interarrival times such as by using a lognormal random or pseudorandom number generator is provided. In yet another embodiment, a system for characterizing traffic on an ATM network is provided. The system includes lognormal number generating means for generating a plurality of at least substantially lognormally distributed values corresponding to the plurality of packets. In yet a further embodiment, a system for characterizing traffic on an ATM network is provided that includes: (i) a lognormal number generator for generating a plurality of at least substantially lognormally distributed values corresponding to the first plurality of packets; and (ii) a normal number generator for generating a plurality of at least substantially normally distributed values corresponding to the second plurality of packets; and (iii) a combiner, in communication with the lognormal number generator and the normal number generator, for combining the plurality of lognormally distributed values and the plurality of normally distributed values to provide an aggregate stream of values. In yet another embodiment, a method for modeling or predicting packet interarrival times on an ATM network is provided. The method includes the steps of: (i) providing (a) a number of packets in a first portion of a plurality of packets that will be transported or have been transported on an ATM network, the packets in the first portion containing at least one of voice and video information and (b) a number of packets in a second portion of the plurality of packets, the packets in the second portion containing information other than the at least one of voice and video information; (ii) generating with a lognormal number generator a plurality of packet interarrival times values corresponding to at least some of the packets in the first portion; and (iii) generating with a normal number generator a plurality of packet interarrival times corresponding to at least some of the packets in the second portion. The summation or combination of the output of the two types of number generators provides a synthetic traffic stream that closely resembles the actual behavior of the modeled ATM system. The foregoing description of the various embodiments of the present invention is intended to be neither complete nor exhaustive. Those of ordinary skill in the art will appreciate that numerous other embodiments can be envisioned using one or more of the components set forth above. For example, a variety of systems can be envisioned for performing the method steps noted above. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow diagram of an ATM switching architecture; FIG. 2 is a flow diagram of a modeling architecture according to an embodiment of the present invention; FIG. 3 is a flow schematic of software according to another embodiment of the present invention; FIGS. 4A and 4B are plots of number of packet arrivals (vertical axis) against packet interarrival time (horizontal axis) for an ATM network; FIG. 5 is a plot of number of packet arrivals (vertical axis) against packet interarrival time (horizontal axis) for synthetic data for an ATM network; FIG. 6 is a plot of number of packet arrivals (vertical axis) against packet interarrival time (horizontal axis) for an ATM network; and FIG. 7 is another plot of number of packet arrivals (vertical axis) against packet interarrival time (horizontal axis) for synthetic data for an ATM network. DETAILED DESCRIPTION Referring to FIG. 1 , a typical ATM switching architecture is depicted. The ATM switch 10 includes a switch buffer 14 and switch controller 18 . Although an ATM cell or packet in the traffic 22 entering the switch 10 contain bits for discard priority, it is preferable to slow the traffic 22 down rather than degrade the level of service by discarding packets. Flow-control mechanisms in the switch controller 18 limit the arrival rate when the distination buffers become full. In other words, packets which arrive after the buffer is full must wait until buffer space is made available by departing packets. The overflow traffic can thus result in a virtual overflow buffer 26 whose size depends on the transmission speed and buffer size of the switch. As cells are drained away from the buffer 14 , cells waiting in the virtual overflow buffer 26 are admitted to the buffer 14 . A very desirable feature of ATM switches is that they are priority-based and policy-based. Priority-based refers to an ATM switch's capability to assign an admission and transmission priority to an ATM cell based on the type of information it caries (voice, video, or data). Policy-based refers to an ATM switch's capability to assign admission and transmission priority to an ATM cell based on both the type of information it is carrying and the time of day. For example, voice usually has a higher priority than data. However, a switch administrator might want to give data the highest priority for certain hours of the day for example, late at night. Thus, an ATM based network gives network administrators much control over shaping the characteristics of traffic on their networks. Packets passing through the switch can have a broad range of packet interarrival times at their respective destinations. Because voice and video packets have higher admission priority to the switch buffer 14 and much higher sensitivity to delay, packets containing such information typically have short packet interarrival times. In contrast, packets containing information other than voice or video have a lower admission priority to the buffer 14 and will typically have a wide range of packet interarrival times ranging from short interarrival times to long interarrival times, depending on the volume of higher priority packets received by the switch. The broad range of packet interarrival times defines a bimodal probabilistic distribution. The packets having shorter interarrival times define a substantially lognormal probabilistic distribution while those having longer interarrival times define a substantially normal or self-similar probabilistic distribution. As will be appreciated, a lognormal distribution is a continuous distribution of a random variable whose logarithm is normally distributed. It typically resembles a positively or negatively skewed curve. The typical probability density function of a random variable X having Λ(μδ 2) is: P ⁡ ( x ) = { x ≥ 0 1 2 ⁢ πσ ⁢ ⅇ - ( x - μ ) 2 / 2 ⁢ σ 2 x ≤ 0 where, μ is the mean δ the standard deviation and δ 2 the variance. A typical probability density function for a normal or Gaussian distribution is: P ⁡ ( x ) = { - ∞ ≤ x ≥ ∞ 1 2 ⁢ πσ ⁢ ⅇ - ( x - μ ) 2 / 2 ⁢ σ 2 where X is a random variable, μ is the mean, δ the standard deviation, and δ 2 the variance. Referring to FIG. 2 , an architecture for modeling or simulating packet interarrival times in an ATM switch is illustrated. The architecture 50 includes inputs 54 and 58 , normal number generator 62 for generating an at least substantially normally distributed set of interarrival times, lognormal number generator 66 for generating an at least substantially lognormally distributed set of interarrival times, and combiner 70 . Input 54 inputs the number of packets (in the packet stream 22 passing through the ATM switch) having normally distributed packet interarrival times and the mean and variance of the corresponding normal distribution into the normal number generator 62 . Input 58 inputs the number of packets (in the packet stream 22 passing through the ATM switch) having lognormally distributed packet interarrival times and the mean and variance of the corresponding lognormal distribution into the lognormal number generator 66 . Although any random or pseudorandom number generator that produces values having the desired probabilistic distribution can be used for the number generator, preferred random or pseudorandom generators are the MATLAB™ lognormal and normal random or pseudorandom number generator programs distributed by The MathWorks, Inc. The combiner 70 combines the outputs 74 and 78 from the generators 62 , 66 , respectively, to form a synthetic traffic stream 82 . The synthetic traffic stream 82 replicates the distribution of packet interarrival times resulting from the ATM switch 10 and the mixture of packet types in the traffic 22 entering the switch 10 . FIG. 3 is a flow schematic of an embodiment of a method for operating the architecture of FIG. 2 . In box 100 , the user must determine the traffic mixture. In a typical ATM network, the traffic 22 is characterized or defined in terms of the share or percentage of the packets in the traffic 22 entering the switch that contain voice information, that contain video information, and/or that contain data (information other than voice and/or video information). With this mixture, the number of packets containing each type of information, namely voice, video, and data, can be determined by multiplying the percentages by the total number of packets passing through or routed by the switch during a selected time interval. In some applications, a volumetric range of packets in each category (voice, video, and data) will be determined. In some applications, packets (such as those containing data) will have interarrival times characterized by a bimodal distribution; that is, some of the packets will have interarrival times that are distributed normally and other of the packets will have interarrival times that are distributed lognormally. In such applications, the numbers of packets in each category must be determined. This can be done by assigning a percentage or range of percentages to the portion of the packets having normally distributed interarrival times and/or lognormally distributed interarrival times. These percentages or ranges of percentages can then be multiplied by the total number of packets passing through or routed by the switch in a specified time interval to yield the number of packets in each category (i.e., having normally or lognormally distributed interarrival times). In box 104 , the pertinent input parameters are input into the normal number generator 62 and lognormal number generator 66 . For the normal number generator 62 , the input variables are the mean and variance of the normal distribution of the data packet interarrival times (that are distributed normally) and the total number of data packets of this type passing through the switch during the selected time interval. For the lognormal number generator 66 , the input variables are the mean and variance of the lognormal distribution of the data packet interarrival times (that are distributed lognormally) and the total number of data packets of this type passing through the switch during the selected time interval. In boxes 108 and 112 , number generators each generate and output values that can be a serial stream of packet interarrival times and/or a series of sets of values, e.g., a packet interarrival time and the number of packets corresponding to the packet interarrival time. The total number of values generated by each generator is typically equivalent to the number of data packets having normally distributed interarrival times (for the normal number generator) and to the number of data packets having lognormally distributed interarrival times (for the lognormal number generator). The outputted values from each number generator are combined in a summing step 116 to form a composite traffic stream of data packet interarrival times. In box 120 , parameters are inputted into a lognormal number generator 66 (which may be the same or different from the generator 66 operated in box 108 ) in relation to the packets containing voice and/or video information. The inputted variables include the total number of packets containing voice and/or video information that are routed by the switch during the selected time interval and the mean and variance of the lognormal distribution of the voice and/or video packet interarrival times. In certain applications, the lognormal distributions of voice packets on the one hand and video packets on the other are different. In such situations, separate lognormal number generators 66 can be used to handle the differing input parameters (i.e, the differing numbers of voice and video packets, the differing means and variances of the two distributions, and the like). In box 124 , a stream of values are generated by the lognormal number generator. As noted, the values can be a serial stream of packet interarrival times and/or a series of sets of values, namely a packet interarrival time and the number of packets corresponding to the packet interarrival time. The number of values outputted by the number generator 66 is typically the same as the total number of voice and/or video packets routed by the ATM switch during the selected time interval. In box 128 , the composite traffic stream of data packet interarrival times (from box 116 ) and the stream of voice and video packet interarrival times (from box 124 ) are combined to produce a synthetic traffic stream 132 . The synthetic traffic stream 132 can be used to design the various components of the ATM network. For example, the traffic stream 132 can be used to determine the required number of buffers and/or buffer capacity, the desired transmission speed of packets, peak delay of traffic stream and optimum traffic mix (e.g., voice, video or data) of an ATM traffic channel. EXPERIMENTAL FIGS. 4A and B present actual data taken from an ATM network. The network was serviced by a Fujitsu FETEX-150™ multi-service switching platform providing ATM switching services in the network. The host ATM was implemented using self-routing modules in a multi-stage network. It provided switching functions and served as the center for call processing and operations, administration, maintenance, and provisioning. Two broadband remote switching units in the network contained the customer interfaces and performed line concentration functions. Three customer sites were connected to the ATM network in a physical star configuration via Synchronous Optical NETwork (SONET) fiber links operating at 622.08 Mb/s (OC-12 rate). Forty-one files were obtained, fifteen of which were corrupted and unusable. The data was collected during eight data collection sessions on four different days over a four month period. Busy hour sampling was performed because packet interarrival processes were non-stationary. The data files were uncompressed and processed with a statistical analysis program. The statistical analysis program provided a file with the number of data cells, data bursts, interarrival cells, and interarrival bursts in the data. The file also contained the traffic data stream itself represented as a column of integers. The traffic data stream from each file was separated into three files: (i) the complete traffic data stream, (ii) the data cell traffic stream, and (iii) the interarrival cell stream. The data files were input into MATLAB™ for analysis. The individual files within a session were analyzed individually and then concatenated and analyzed collectively. Since the results from the eighth session were representative of the entire body of data and since this was one of the larger data sets, the results from this session will be discussed below. FIGS. 4A and B are histograms of the interarrival times for this session. As can be seen from FIGS. 4A and B, the histogram appears as a mixture of two distributions: a large lognormal distribution 150 for packet interarrival times of about 0.3×10 −4 seconds or less and a much smaller normal distribution 154 for packet interarrival times exceeding about 0.3×10 −4 seconds. The much smaller normal distribution 154 caused by the switch input buffer filling up. These delayed packets form queues which are similar in length and distribution to Ethernet packets (which have normally distributed packet interarrival times). The majority of the interarrival times were very short in length, with the mean interarrival time being approximately 0.3×10 −4 seconds. Model fitting was performed to characterize the curve defining the data in FIG. 4B . The following model was developed: F(x)=Ψ·Λ(μ a .δ 2 1 ,)+(1−Ψ)·N(μ 2 ,δ 2 2 ) where the mixing parameter, Ψ, is about 0.97, μ 1 , the mean of the lognormal distribution 150 , is about −12.0156, δ 1 2 , the variance of the lognormal distribution 150 , is about 1.3850. μ 2 , the mean of the normal distribution 154 , is about 6.1293×10 −5 , and δ 2 2 the variance of the normal distribution 154 , is about 1.6464×10 −5 . Using the means and variances of the model and the sample size of FIGS. 4A and 4B , the data in FIG. 5 was generated using lognormal and normal random number generators in MATLAB™. A comparison of FIGS. 4A and 5 demonstrates the close correlation between the actual and synthetic data. Of course, a simple moment matching model will not perform well in capturing the burst pattern characteristics of the data. An algorithm which synthesizes the buffering and transmission characteristics of the sending and receiving mechanisms would produce burst patterns similar to those of real traffic. In the model, the mixture parameter, Ψ, is dependent on (i) the speed at which traffic enters and leaves the switch, (ii) the priority of the traffic, and (iii) the size of the switch input buffers. As the transmission speed and/or buffer size increases, the parameter Ψ tends to 1 and the traffic distribution tends to total lognormality. Another ATM local area network was designed and built for the purpose of investigating the architecture and management algorithms appropriate to the local area. The network architecture is a manageable network, i.e., both the network resources and resource demands made by traffic are identifiable and quantifiable. An ATM camera was set up to transmit 25 frames per second, JPEG compressed, 24 bits per pixel color video from a regular television transmission. The ATM camera transmitted cells to a network port controller which performed the traffic measurements, and from there to a Sun Sparc 10 workstation which displayed the video. The traffic trace is the first 1000000 cells of transmission, which included both action scenes (an explosion) and relatively static portions when credits were rolling on the screen. FIG. 6 is a histogram plot of the camera data. The histogram of traffic interarrival times is heavy tailed and contains a relatively small normal distribution 160 after main lognormal distributions 170 a–c . The peak in the tail 160 is around 0.225 msec, which is nearly four times the magnitude of the peak in the tail 154 of FIG. 4A (around 0.06 msec). The input buffers of the ATM switches in both requirements were 128k bytes. The higher egress speed of the architecture in the first experiment allowed the buffers to clear faster, which resulted in less cell delay and a lighter tail distribution. Model fitting was performed to characterize the curve defining the data in FIG. 6 . The following model was developed for the curve which had three lognormal distributions 170 a–c and one normal distribution 160 : F ( x )=(0.20 Ψ)·Λ(μ 1 ,δ 2 1 )+(0.20 Ψ)˜Λ 2 (μ 2 .δ 2 2 )+(0.60 Ψ)˜Λ 3 (μ 3 ,δ 2 3 )+(1−Ψ)· N (μ 4 ,δ 2 4 ) where the mixing parameter, Ψ, is about 0.98, μ 1 , the mean of the first lognormal distribution 170 a , is about −11.5784, δ 1 2 , the variance of the first lognormal distribution 170 a , is about 0.5194, μ 2 , the mean of the second lognormal distribution 170 b , is about −10.3165, δ 2 2 , the variance of the second lognormal distribution 170 b , is about 0.1997, μ 3 , the mean of the third lognormal distribution 170 c , is about −9.3908, δ 3 2 , the variance of the third lognormal distribution 170 c , is about 0.3095, μ 4 , the mean of the normal distribution 160 , is about 2.2546×10 −4 , and δ 4 2 , the variance of the normal distribution 160 , is about 2.1980×10 −5 . The first and second lognormal distributions 170 a and b were each deemed to be 20% of the total lognormal distribution 170 a–c , and the third lognormal distribution 170 c was deemed to be 60% of the total lognormal distribution 170 a–c. FIG. 7 is a histogram generated with the MATLAB™ lognormal and normal random number generators using the means and variances in the model and the sample size in FIG. 6 . As in the case of FIGS. 4A and B and 5 , the computer generated data in FIG. 7 closely correlates with the actual data in FIG. 6 . The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and the skill or knowledge of the relevant art, are within the scope of the present invention. By way of example, the architecture of FIG. 2 could have a number of lognormal and/or normal random number generators operating in parallel on differing portions of the packet stream. This may be the case for data, voice, and video packets or different lognormal distributions within a packet type or among packet types such as those in FIG. 6 . Alternatively, the lognormally distributed interarrival times for voice, video and data packets can be replicated using a single lognormal random number generator. The embodiments described herein above are further intended to explain best modes known for practicing the invention and to enable others skilled in the art to utilize the invention in such, or other, embodiments and with various modifications required by the particular applications or uses of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.

The present invention is directed to a traffic simulation algorithm for an asynchronous transfer mode communications (ATM) network. The algorithm recognizes that packets in ATM networks can have interarrival times that are lognormally distributed or lognormally and normally distributed. Lognormal and, in some cases, normal random number generators are used to generate packet interarrival times of a synthetic traffic stream.