Patent Publication Number: US-2006012700-A1

Title: Lens apparatus and image synthesis system

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a lens apparatus, and more particularly, but not exclusively, to a lens apparatus configured to be used with at least one of an image synthesis apparatus, an image capture apparatus, and an image synthesis system.  
      2. Description of the Related Art  
      A conventional television lens allows a user to create a desired video scene by electrically or manually operating a movable optical member (e.g., a zoom lens, a focus lens, an iris mechanism, or an extender), (attached to a television camera) to produce an optical change.  FIG. 17  illustrates a block diagram schematically showing an example of a conventional television lens system. In  FIG. 17 , the television lens system includes a television lens  100  and a television camera  120 . The television lens  100  is mounted on the television camera  120 . The television lens system further includes a zoom demand  121 , a focus demand  122 , and demand connectors  123  and  124 . The zoom demand  121  is operable by the user to perform zooming of the television lens  100 . The focus demand  122  is also operable by the user to perform focusing of television lens  100 . The demand connectors  123  and  124  are adapted to connect the zoom demand  121  and the focus demand  122  to the television lens  100 , respectively. In such a television lens system, a potentiometer or a rotary encoder is coupled to a movable optical member (e.g., a zoom lens or a focus lens), and is used as a position detection unit for detecting the position of the optical member to perform servo driving or to provide position indication.  
      Television lenses are classified into large-sized high-performance lenses suitable for use in a studio and portable handy lenses suitable for outdoor use or carryable on the user&#39;s shoulder. In the large-sized lens, a digital encoder for outputting a two-phase digital signal is generally used as a position detection unit, while in the handy lens, a potentiometer for outputting an analog voltage is generally used (see U.S. Patent Application Publication No. U.S. 2002/0122113 A1, Japanese Laid-Open Patent Application No. 2004-056742, Japanese Laid-Open Patent Application No. 2000-270261, U.S. Patent Application Publication No. U.S. 2001/0028463 A1, Japanese Laid-Open Patent Application No. 2000-270203, U.S. Pat. No. 6,034,740, Japanese Laid-Open Patent Application No. 2004-134950, European Patent Application Publication No. EP 0989747 A2, and Japanese Laid-Open Patent Application No. 10-303838).  
      In addition, various virtual systems for merging a real video image with a compute-generated image associated with the real video image have been actively developed. In these virtual systems (e.g., image synthesis apparatus), the above-described large-sized television lens or handy television lens is used.  
      In an image synthesis system using such a virtual system, a position detection signal indicating the position of a movable optical member of the television lens (zoom position, focus position) is transmitted to the virtual system. This enables a computer incorporated in the virtual system to create a computer-generated image matched with the size and focus position of a real video image. Accordingly, even when the zoom lens, the focus lens, or other optical elements are operated in real time, a synthesized video image can be created without producing an unconventional view to the user.  
      Conventionally, there has been no dedicated or standardized method of connecting the television lens to the virtual system. In a conventional image synthesis system, existing connection components of the television lens are temporarily used, or the television lens is so modified as to conform to the virtual system. As to connection between the virtual system and the television lens, there are three connection methods as described below, i.e., a connection method using a digital pulse train, a connection method using an analog voltage signal, and a connection method using data communication.  
       FIG. 13  illustrates a block diagram schematically showing a conventional image synthesis system in which a virtual system  200  is connected to a television lens  100  incorporating a digital encoder (ENC)  109  as a position detection unit. The television lens  100  includes a CPU (central processing unit)  101 , a D/A (digital-to-analog) converter  102 , a power amplifier  103 , a motor  104 , a zoom lens  105 , a digital encoder  109 , and a counter  110 . The CPU  101  controls each part of the television lens  100 . The D/A converter  102  receives a command value from the CPU  101  for performing zooming. The power amplifier  103  amplifies the command value from the D/A converter  102 . The motor  104  is driven based on an amplified signal from the power amplifier  103  and then the zoom lens  105  is driven by the motor  104  to perform zooming. The digital encoder  109  functions as a zoom position detection unit for detecting the zoom position of the zoom lens  105 . The counter  110  counts a two-phase pulse signal outputted from the digital encoder  109  to calculate the zoom position. While, in  FIG. 13 , only the zoom lens  105  is shown as a movable optical member in the television lens  100 , a focus lens, an iris mechanism, and an extender are also configured in a similar manner as the zoom lens  105 .  
      When a command device (zoom demand)  121  ( FIG. 17 ), connected to the television lens  100 , is operated by the user to transmit a command to the television lens  100 , the CPU  101  compares the current zoom position supplied from the counter  110  with the command signal from the command device  121  so as to calculate a new zoom command position. The CPU  101  then outputs the new zoom command position to the D/A converter  102  to control the position of the zoom lens  105 . A two-phase pulse interface signal  301 , outputted from the digital encoder  109 , is transmitted as a zoom position signal to the virtual system  200 . The virtual system  200  includes a CPU  201  and a counter  202 . The counter  202  calculates the zoom position of the zoom lens  105  based on the two-phase pulse interface signal  301  received from the television lens  100 . The CPU  201  receives, in addition to the zoom position signal from the counter  202 , a focus position signal from a focus counter (not shown), an iris position signal, an extender position signal, and a video signal from a television camera (not shown) connected to the television lens  100 . Computer-generated image data created in the virtual system  200  is processed based on information on the position of the zoom lens  105 , etc., so as to be matched with a video signal from the television camera. The processed computer-generated image data and the video signal from the television camera are merged together to create a virtual video image (synthesized video image) not producing an unconventional view to the user.  
       FIG. 14  illustrates a diagram illustrating the two-phase pulse interface signal  301 , which is transmitted from the television lens  100  to the virtual system  200 . The two-phase pulse interface signal  301  is digitized as illustrated in  FIG. 14  and is used to calculate relative position data and absolute position data. In a case where a television lens incorporating a digital encoder is connected to a virtual system as shown in  FIG. 13 , detection information obtained from the digital encoder, which is also used for servo control, is transmitted to the virtual system to perform image synthesis. However, in order to enable detection information obtained from the digital encoder, which is also used for servo control of the zoom lens, to be transmitted to the virtual system, the configuration of the television lens needs to be modified.  
       FIG. 15  illustrates a block diagram schematically showing a conventional image synthesis system in which a virtual system  210  is connected to a television lens  160  incorporating a potentiometer in place of a digital encoder. Since a position detection unit for detecting the zoom position of the zoom lens  105  is a potentiometer (POT)  106  configured to output an analog signal, the television lens  160  includes an operational amplifier  107  and an A/D (analog-to-digital) converter  108 . While, in  FIG. 15 , only the zoom lens  105  is shown as a movable optical member in the television lens  160 , a focus lens, an iris mechanism, and an extender are also configured in the similar manner as the zoom lens  105 . In addition, the virtual system  210  includes an operational amplifier  203  for interface matching and an A/D converter  204  in place of the counter  202 . In such a configuration, an interface signal  302  transmitted from the television lens  160  to the virtual system  210  is an analog voltage signal, as illustrated in  FIG. 16 .  
      In the case where the television lens, incorporating a potentiometer in place of a digital encoder, is connected to a virtual system as illustrated in  FIG. 15 , detection information obtained from the potentiometer  106 , which is also used for servo control, is transmitted to the virtual system to perform image synthesis. However, in order to enable detection information obtained from the potentiometer, to be transmitted to the virtual system, the configuration of the television lens needs to be modified.  
       FIG. 18  illustrates a block diagram schematically showing a conventional image synthesis system in which a virtual system  220  is connected to a television lens  180  via data communication. In  FIG. 18 , a signal from the digital encoder  109  is not directly transmitted to the counter  202  ( FIG. 13 ) in the virtual system  200 . More specifically, the CPU  181  in the television lens  180  reads a value from the counter  110 , and a communication processing unit  112  contained in the CPU  181  transmits, via data communication, position information on the zoom lens  105 , the focus lens, etc., as an interface signal  303  to a communication processing unit  205  of the CPU  207  in the virtual system  220  so as to create a virtual video image (synthesized video image).  
      In a case where a television lens is connected to a virtual system via data communication as illustrated in  FIG. 18 , a dedicated communication line needs to be provided in addition to communication lines used for communication between the television lens and demands. Therefore, the configuration of the standard television lens needs to be modified.  
      As described above, in conventional television lenses, there is no connection method (interface) applicable to connect with a virtual system. Accordingly, the configuration of the standard television lens needs to be modified with respect to both hardware and software.  
      In particular, connection methods (interfaces) are limited depending upon the type of position detection unit of the television lens. Additionally, a connection method using data communication with a dedicated communication protocol can depend on the request from the virtual system. Thus, standard television lens cannot have standard connection methods (interfaces).  
      In addition, a conventional virtual system possesses optical data corresponding to a television lens in use, and refers to the optical data to calculate data corresponding to the relative positions of a zoom lens, a focus lens, etc. . . . Therefore, optical data have to be exchanged each time television lenses are exchanged.  
     SUMMARY OF THE INVENTION  
      At least one exemplary embodiment is directed to a lens apparatus which can be configured to be used with an image synthesis apparatus via a standard connection unit. In at least one exemplary embodiment, the standard connection unit can be disposed between the lens apparatus and the image synthesis apparatus, without having to modify the configuration of the lens apparatus. In yet a further exemplary embodiment, a connection method using data communication with a general-purpose and standard protocol can be used with the connection unit.  
      In addition, at least one exemplary embodiment is directed to an image synthesis system in which it is unnecessary to change optical data stored in an image synthesis apparatus even if lens apparatuses are exchanged.  
      In at least one exemplary embodiment, a lens apparatus configured to communicate with an image synthesis apparatus can include a movable optical member, a position detection unit configured to detect a position of the movable optical member to generate a position information signal, an arithmetic processing unit configured to, based on the position information signal generated by the position detection unit, create an optical information signal that is recognizable by the image synthesis apparatus, and a communication unit configured to transmit the optical information signal to the image synthesis apparatus.  
      Particularly, in at least one further exemplary embodiment, a lens apparatus can include at least one movable optical member, (e.g., a zoom lens, a focus lens, an iris mechanism, or an extender), a position detection unit configured to detect a position of the movable optical member, and a control unit configured to recognize position detection information obtained by the position detection unit and to perform driving control of the movable optical member and, in some embodiments, communicate with a command instruction unit for a user. The lens apparatus can further include a signal input/output unit for image synthesis. The signal input/output unit can have three transmission methods, including a first transmission method which can use an analog voltage signal, a second transmission method which can use a digital pulse train, and a third transmission method which can use data communication from the control unit. Accordingly, the lens apparatus can be connected to an image synthesis apparatus even if any one of the first, second, and third transmission methods is requested by the image synthesis apparatus. Thus, the image synthesis system can be configured without modifying the configuration of the lens apparatus.  
      At least one exemplary embodiment is configured to facilitate connection between the lens apparatus and the image synthesis apparatus even if the image synthesis apparatus does not possess optical data inherent in the lens apparatus. In addition, data transmitted by the signal input/output unit for image synthesis can include relative position data on the zoom lens, the focus lens, the iris mechanism, the extender, or other optical elements. Accordingly, using this particular exemplary embodiment, connection between the lens apparatus and the image synthesis apparatus can be established, even if the image synthesis apparatus does not possess optical data inherent in the lens apparatus.  
      In another exemplary embodiment, the lens apparatus can further include a storage unit, which can store optical data inherent in the lens apparatus. The lens apparatus can create transmission data from new optical data by using position information (e.g., on the zoom lens, the focus lens, the iris mechanism, the extender, or other optical elements), an arithmetic program, and an arithmetic processing unit. The optical data can be at least one of an angle of view, a principal point, an object distance, a focal length, a depth of field, a depth of focus, and an iris F-number that vary in association with the driving of the zoom lens, the focus lens, the iris mechanism, the extender, or other optical elements.  
      In at least one exemplary embodiment, optical data stored in the lens apparatus can be used to calculate new optical data associated with the driven position of the zoom lens, the focus lens, the iris mechanism, the extender, or other optical elements and transmitted to the image synthesis apparatus. Accordingly using this particular exemplary embodiment, the image synthesis apparatus need not possess data inherent in the lens apparatus, nor does the image synthesis apparatus need to calculate optical position data for image synthesis.  
      In a further exemplary embodiment, the lens apparatus can further includes a data structure selection setting unit configured to select and set a data structure of transmission data transmitted by the signal input/output unit for image synthesis. Accordingly, in an exemplary embodiment, the data structure corresponding to data for the image synthesis apparatus can be obtained, and an image synthesis system can be configured without modifying the configuration of the lens apparatus.  
      In a further exemplary embodiment, transmission data transmitted by the signal input/output unit for image synthesis can be transmitted in synchronization with specific received data or a specific input signal. Accordingly, when a specific command is received from the image synthesis system in synchronization with a video signal, or when a specific input signal is received, the exemplary embodiment of the lens apparatus can transmit data to the image synthesis apparatus. Thus, using this particular exemplary embodiment, the image synthesis system that is synchronized with a video signal can be configured without modifying the configuration of the lens apparatus.  
      Other features of the present invention will become apparent to those skilled in the art upon reading the following detailed description of exemplary embodiments thereof when 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  
      Embodiments of the present invention will become apparent from the following detailed description, taken in conjunction with the drawings.  
       FIG. 1  illustrates a schematic block diagram showing a television lens according to a first exemplary embodiment.  
       FIGS. 2A and 2B  illustrate diagrams showing digital pulse trains outputted from the television lens according to the first exemplary embodiment.  
       FIG. 3  illustrates a flow chart showing a processing operation performed by a CPU included in the television lens according to the first exemplary embodiment.  
       FIG. 4  illustrates a schematic block diagram showing a television lens according to a modification of the first exemplary embodiment.  
       FIG. 5  illustrates a flow chart showing a processing operation performed by a CPU included in the television lens according to the modification of the first exemplary embodiment.  
       FIG. 6  illustrates a schematic block diagram showing an image synthesis system including the television lens according to the first exemplary embodiment.  
       FIG. 7  illustrates a diagram showing an example of a communication data string including relative position data transmitted from a communication processing unit included in the television lens according to the first exemplary embodiment.  
       FIG. 8  illustrates a schematic block diagram showing a television lens according to a second exemplary embodiment.  
       FIG. 9  illustrates a diagram showing an example of a communication data string including optical data transmitted from a communication processing unit included in the television lens according to the second exemplary embodiment.  
       FIG. 10  illustrates a diagram showing an example of a communication data string set by a data structure selection setting unit according to a third exemplary embodiment.  
       FIG. 11  illustrate a diagram showing the sequence of transmission of a communication data string at the time of receiving a synchronization command in a television lens according to a fourth exemplary embodiment.  
       FIG. 12  illustrate a diagram showing the sequence of transmission of a communication data string at the time of receiving a vertical synchronization signal according to the fourth exemplary embodiment.  
       FIG. 13  illustrate a schematic block diagram showing a conventional image synthesis system.  
       FIG. 14  illustrate a diagram showing digital pulse trains outputted from a television lens in the conventional image synthesis system shown in  FIG. 13 .  
       FIG. 15  illustrate a schematic block diagram showing another conventional image synthesis system.  
       FIG. 16  illustrate a diagram showing an analog voltage signal outputted from a television lens in the conventional image synthesis system shown in  FIG. 15 .  
       FIG. 17  illustrate a schematic block diagram showing a conventional television lens system.  
       FIG. 18  illustrate a schematic block diagram showing a further conventional image synthesis system. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
      The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.  
      Processes, techniques, apparatus, and materials as known by one of ordinary skill in the art may not be discussed in detail but are intended to be part of the enabling description where appropriate. For example analog to digital (A/D) converters are used in some exemplary embodiments. Any type of A/D converter and material that can be used to form an analog to digital converter should fall within the scope of exemplary embodiments. Likewise for the rest of the elements of exemplary embodiments.  
      Additionally the actual size of the elements of any lens apparatus or other elements of exemplary embodiments may not be discussed, however any size from macro to micro to nano are intended to lie within the scope of exemplary embodiments (e.g., lenses with diameters of nanometer size, micro size, centimeter, and meter sizes).  
      Additionally exemplary embodiments are not limited to visual systems, for example the system can be designed for use with infrared and other wavelength systems.  
      Exemplary embodiments will be described in detail below with reference to the drawings.  
     First Exemplary Embodiment  
       FIG. 1  illustrates a schematic block diagram showing a television lens  150  incorporating a potentiometer as a position detection unit according to a first exemplary embodiment.  
      In  FIG. 1 , the television lens  150  can include a CPU (central processing unit)  151 , a D/A (digital-to-analog) converter  102 , a power amplifier  103 , a motor  104 , a zoom lens  105 , a zoom potentiometer  156 , an operational amplifier  107 , an A/D (analog-to-digital) converter  108 , and an operational amplifier  113 . The CPU  151  controls each part of the television lens  150 . The D/A converter  102  receives a command value from the CPU  151  for performing zooming. The power amplifier  103  amplifies the command value from the D/A converter  102 . The motor  104  is driven based on an amplified signal from the power amplifier  103 . The zoom lens  105  is driven by the motor  104  to perform zooming. The zoom potentiometer  156  functions as an analog zoom position detection unit operatively connected with the zoom lens  105 . The operational amplifier  107  functions as a matching circuit to enable an analog signal from the zoom potentiometer  156  to be inputted into the CPU  151 . The A/D converter  108  digitizes the matched analog zoom position signal. The operational amplifier  113  transmits the analog position signal from the zoom potentiometer  156 , as an analog voltage output signal  115 , to an external virtual system  230  ( FIG. 6 ). The CPU  151  includes a communication processing unit  152  and an analog position/digital pulse conversion unit  114 . The analog position/digital pulse conversion unit  114  converts position data received from the A/D converter  108  into a digital pulse train output signal  116  and transmits the digital pulse train output signal  116  to the external virtual system  230 .  
       FIGS. 2A and 2B  illustrate diagrams showing an example of digital pulse trains outputted from the analog position/digital pulse conversion unit  114 . In particular,  FIG. 2A  illustrates a two-phase phase-difference signal, and  FIG. 2B  illustrates a two-phase up/down pulse signal. The communication processing unit  152  converts position information on the zoom lens  105 , a focus lens, an iris mechanism, an extender, and other optical elements, received (1001) by the CPU  151  into a data communication input/output signal  118  and transmits the data communication input/output signal  118  to the external virtual system  230  via data communication (e.g., physical layer interfaces, RS-232, RS-422, RS-456, USB (universal serial bus), Bluetooth®, equivalents, and other communication protocol and methods as known by one of ordinary skill in the relevant art). The CPU  151  also transmits an extender output signal  117 , which is a one-bit or two-bit digital output, to the external virtual system  230 .  
      The television lens  150  further can include an input/output connector  119  for image synthesis. The input/output connector  119  can be used to transmit three types of signals to the external virtual system  230  (e.g., the analog voltage output signal  115 , the digital pulse train output signal  116 , and the data communication input/output signal  118 ), in addition to the extender output signal  117 . While, in  FIG. 1 , the zoom lens  105  is shown as a movable optical member in the television lens  150 , the focus lens, the iris mechanism, and the extender can also be configured to move in a similar manner as the zoom lens  105 .  
       FIG. 3  illustrates a flow chart showing a processing operation performed by the CPU  151  in the television lens  150  configured as described above. In  FIG. 3 , the CPU  151  starts processing at step S 100 . At step S 101 , the CPU  151  reads a zoom command value from a zoom demand  121  ( FIG. 6 ), which is a command device which can be connected to the television lens  150 . At step S 102 , the CPU  151  reads zoom position data from the A/D converter  108 .  
      At step S 103 , the CPU  151  calculates a driving command value for driving the zoom lens  105  from the zoom command value obtained at step S 101  and the zoom position data obtained at step S 102  and outputs the driving command value to the D/A converter  102 . Accordingly, the zoom motor  104 , the zoom lens  105 , and the zoom potentiometer  156  can be sequentially operated in an interlocking manner. Thus, the zoom lens  105  is moved along an optical axis to obtain a desired video image.  
      At step S 104 , the analog position/digital pulse conversion unit  114  in the CPU  151  is configured to process and transmit the digital pulse train output signal  116  to the external virtual system  230 . Thus, the analog position/digital pulse conversion unit  114  generates two-phase digital pulse trains shown in  FIGS. 2A and 2B  to enable position information to be transmitted to the external virtual system  230 .  
      At step S 105 , the communication processing unit  152  in the CPU  151  is configured to process and transmit the zoom position data obtained at step S 102  to the external virtual system  230  in accordance with a predetermined communication format.  FIG. 7  illustrates an example of a data string transmitted at step S 105 . In  FIG. 7 , the data string processed and transmitted at step S 105  includes relative position data on the zoom lens  105 , the focus lens, the iris mechanism, and the extender.  
      At step S 106 , the CPU  151  is configured to process and transmit a one-bit or two-bit digital value corresponding to the magnification value of the mounted extender, as the extender output signal  117 , to the external virtual system  230 . The CPU  151  then returns to step S 101  to repeat the above-described processing.  
      In addition, when the zoom potentiometer  156  is moved in association with driving of the zoom lens  105 , an analog voltage output signal  115 , corresponding to the movement of the zoom potentiometer  156 , can be generated to be transmitted to the external virtual system  230  through the operational amplifier  113 .  
      The television lens  150  according to the first exemplary embodiment can have the above-described configuration and perform processing in accordance with the above-described flow chart of  FIG. 3 . In addition, the television lens  130  can include the input/output connector  119  for image synthesis to employ three transmission methods for position information on the zoom lens  105 , the focus lens, the iris mechanism, the extender, and other optical elements (e.g., a method which can use the analog voltage output signal  115 , a method which can use the digital pulse train output signal  116 , and a method which can use the data communication input/output signal  118 ). Thus, the television lens  150  according to the first exemplary embodiment can be connected to any virtual system  230  described in the conventional image synthesis systems without modifying the configuration of the television lens  130 .  
       FIG. 4  illustrates a schematic block diagram showing a television lens  170  incorporating a digital encoder  159  as a position detection unit according to a modification of the first exemplary embodiment.  
      In  FIG. 4 , the television lens  170  includes a digital encoder  159  as a zoom position detection unit in place of the potentiometer  156  shown in  FIG. 1 . The digital encoder  159  outputs a two-phase digital signal indicating the zoom position of the zoom lens  105 . In  FIG. 4 , the same or similar elements as those shown in  FIG. 1  are omitted from description here (e.g.,  175  in  FIG. 4  is similar to  115  in  FIG. 1 , as are  176  to  116 ,  177  to  117 , and  178  to  118 ). The television lens  170  further includes a counter  110 , a buffer amplifier  130 , an additional D/A converter  131 , and an operational amplifier  132 . The counter  110  counts an output value from the digital encoder  159  to obtain the current zoom position of the zoom lens  105 . The buffer amplifier  130  converts the output value from the digital encoder  159  into a digital pulse train output signal  176  to be transmitted to the external virtual system  230 . The D/A converter  131  converts a digital signal indicating the zoom position obtained by the CPU  171  through the counter  110  into an analog voltage output signal  175 . The operational amplifier  132  transmits the analog voltage output signal  175  to the external virtual system  230 .  
       FIG. 5  illustrates a flow chart showing a processing operation performed by the CPU  171  in the television lens  170  shown in  FIG. 4 . In  FIG. 5 , the CPU  171  starts processing at step S 200 . At step S 201 , the CPU  171  reads a zoom command value from the zoom demand  121 , which is a command device that can be operatively connected to the television lens  170 . At step S 202 , the CPU  171  reads zoom position data from the counter  110 .  
      At step S 203 , the CPU  171  calculates a driving command value for driving the zoom lens  105  from the zoom command value obtained at step S 201  and the zoom position data obtained at step S 202  and outputs the driving command value to the D/A converter  102 . Accordingly, the zoom motor  104 , the zoom lens  105 , and the digital encoder  159  are sequentially operated in an interlocking manner. Thus, the zoom lens  105  is moved along an optical axis to obtain a desired video image.  
      At step S 204 , the CPU  171  outputs the zoom position data obtained at step S 202  to the D/A converter  131  so as to transmit the analog voltage output signal  175  to the external virtual system  230  thorough the operational amplifier  132 .  
      At step S 205 , the communication processing unit  152  in the CPU  101  is configured to process and transmit the zoom position data obtained at step S 202  to the external virtual system  230  in accordance with a predetermined communication format.  
      At step S 206 , the CPU  171  performs processing for transmitting a one-bit or two-bit digital value corresponding to the magnification value of the mounted extender to the external virtual system  230 . The CPU  171  then returns to step S 201  to repeat the above-described processing.  
      In addition, when the digital encoder  159  is moved in association with driving of the zoom lens  105 , a digital pulse train output signal  176  corresponding to the movement of the digital encoder  159  is generated to be transmitted to the external virtual system  230  through the buffer amplifier  130 .  
      The television lens  170  shown in  FIG. 4  has the above-described configuration and performs processing in accordance with the above-described flow chart of  FIG. 5 . In addition, the television lens  170  includes the input/output connector  179  for image synthesis to employ three transmission methods for position information on the zoom lens  105 , the focus lens, the iris mechanism, the extender, and other optical elements, (e.g., a method which can use the analog voltage output signal  175 , a method which can use the digital pulse train output signal  176 , and a method which can use the data communication input/output signal  178 ). Accordingly, the television lens  170  shown in  FIG. 4  can be connected to a virtual system  230  (e.g., as described in the conventional image synthesis systems) without modifying the configuration of the television lens  170 .  
      In the television lens  150  shown in  FIG. 1 , the potentiometer  156  is used as a position detection unit, and in the television lens  170  shown in  FIG. 4 , the digital encoder  159  is used as a position detection unit. However, exemplary embodiments can use any number of position detection devices, as known by one of ordinary skill in the relevant art, where a television lens, in accordance to at least one exemplary embodiment, can be configured to have three transmission methods for position information on the zoom lens  105 , the focus lens, the iris mechanism, the extender, and other optical elements (e.g., a method which can use the analog voltage output signal  115  or  175 , a method which can use the digital pulse train output signal  116  or  176 , and a method which can use the data communication input/output signal  118  or  178 ). Accordingly, a television lens, in accordance with at least one exemplary embodiment, can be connected to any virtual system  230  (e.g.,  200 ,  210 ,  220 , equivalents, and other virtual systems as known by one of ordinary skill in the relevant art, or as described in the conventional image synthesis systems) without modifying the configuration of the television lens.  
       FIG. 6  illustrates a schematic block diagram showing an image synthesis system including the television lens  150  according to the first exemplary embodiment. In  FIG. 6 , the television lens  150  can includes a connector  125  for connection to the virtual system  230  in addition to demand connectors  123  and  124 . Accordingly, the television lens  150  can be connected to a virtual system  230  (e.g.,  200 ,  210 ,  220 , equivalents, and other virtual systems as known by one of ordinary skill in the relevant art, or as described in the conventional image synthesis systems) without modifying the configuration of the television lens  150 .  
       FIG. 7  illustrates a diagram showing an example of a communication data string transmitted from the communication processing unit  152  of the television lens  150  according to the first exemplary embodiment. In  FIG. 7 , a command header (1 byte) indicative of data transmission to the virtual system  230  is transmitted first. After that, relative position data (each 2 bytes) on the zoom lens  105 , the focus lens, the iris mechanism, and the extender are transmitted. Then, an end command (1 byte) indicative of the end of the command data string and a frame check sequence (1 or 2 bytes) serving as an error correction code for the command data string are additionally transmitted. Transmitting such a stylized data string from the television lens  150  facilitates reliable connection of the television lens  150  to the virtual system  230 . Accordingly, an image synthesis system can be established without modifying the configuration of the television lens  150 .  
      In further exemplary embodiments, the data transmission from the television lens  150  to the virtual system  230  can be by methods, techniques and systems as known by one of ordinary skill in the relevant arts (e.g., may be performed by wireless communication).  
     Second Exemplary Embodiment  
       FIG. 8  illustrates a schematic block diagram showing a television lens  190  according to a second exemplary embodiment. As compared with  FIGS. 1 and 4 , the television lens  190  additionally includes a storage unit  140  and an arithmetic processing unit  141 . The storage unit  140  has stored thereon values inherent in the television lens  190  as optical data (e.g. an angle of view, a principal point, an object distance, a focal length, a depth of field, a depth of focus, an F-number, other equivalent optical properties and as known by one of ordinary skill in the relevant art) corresponding to the relative position of the zoom lens  105 , the relative position of the focus lens, the relative position of the iris mechanism, and the relative position of the extender. The arithmetic processing unit  141  calculates optical data values in the relative positions of the zoom lens  105 , the focus lens, the iris mechanism, the extender, and other optical elements, from the optical data stored on the storage unit  140  and the relative position information on the zoom lens  105 , the focus lens, the iris mechanism, the extender, and other optical elements, obtained from position detectors (e.g., potentiometers or encoders).  
      The CPU  191  in the television lens  190  shown in  FIG. 8  performs a processing operation according to the same or similar processing flow as those shown in  FIGS. 3 and 5  except that the arithmetic processing unit  141  performs data communication processing at step S 105  or S 205  as follows. At step S 105  or S 205 , the arithmetic processing unit  141  calculates, using an arithmetic operation (e.g., interpolation, linear interpolation), optical data values corresponding to the current positions from the relative position information on the zoom lens  105 , the focus lens, the iris mechanism, the extender, and other optical elements, obtained prior to step S 105  or S 205  and the optical data (e.g., discrete values such as an angle of view, a principal point, an object distance, a focal length, a depth of field, a depth of focus, an F-number, other equivalent optical properties and as known by one of ordinary skill in the relevant art), stored on the storage unit  140 . The arithmetic processing unit  141  can then output the obtained optical data values as a communication data string to the external virtual system  230  through the communication processing unit  192 .  
       FIG. 9  illustrates an example of the communication data string that can be transmitted from the communication processing unit  192  of the television lens  190  shown in  FIG. 8 . In  FIG. 9 , a command header (1 byte), indicative of data transmission to the virtual system  230  is first transmitted. After that, angle-of-view data, principal point data, and iris F-number data (each 2 bytes) are transmitted. Then, an end command (1 byte) indicative of the end of the command data string and a frame check sequence (1 or 2 bytes) serving as an error correction code for the command data string are additionally transmitted. Transmitting such a stylized data string from the television lens  190  facilitates reliable connection of the television lens  190  to the virtual system  230 . Accordingly, an image synthesis system can be established without modifying the configuration of the television lens  190 . In addition, in accordance with exemplary embodiments, transmitting the optical data values obtained from the relative position information, reduces the need for the virtual system  230  to store optical data on each television lens, to perform an arithmetic operation, or to change optical data at the time of exchange of television lenses. Accordingly, an image synthesis system having good responsivity can be established without modifying the configuration of the television lens.  
     Third Exemplary Embodiment  
      In a third exemplary embodiment, the television lens  190  shown in  FIG. 8  can additionally include a selection setting unit configured to selectively set the structure of a communication data string to a data structure for the virtual system  230 . The selection setting unit can be implemented by using a setting switch, which can be included in the television lens  190 , a communication command (selection setting command) from the virtual system  230 , or from other equivalent systems and/or switching devices.  
       FIG. 10  illustrates an example of the communication data string transmitted to the virtual system  230  according to the third exemplary embodiment. In  FIG. 10 , a command header (1 byte) indicative of data transmission to the virtual system  200  is first transmitted. After that, angle-of-view data and principal point data (each 2 bytes), which are optical data values, and zoom relative position data and focus relative position data (each 2 bytes) are sequentially transmitted. Then, an end command (1 byte) indicative of the end of the command data string and a frame check sequence (1 or 2 bytes) serving as an error correction code for the command data string are additionally transmitted. Providing the selection setting unit in the television lens as described above facilitates the structure of a communication data string to be set to a data structure for the virtual system and also facilitates a data string having relative position data and optical data mixed with each other to be transmitted. Accordingly, an image synthesis system having good responsivity can be established without modifying the configuration of the television lens.  
     Fourth Exemplary Embodiment  
      In a fourth exemplary embodiment, the television lens  190  illustrated in  FIG. 8  can additionally include a synchronization unit (not shown) configured to synchronize the television lens  190  with the virtual system  230 .  FIGS. 11 and 12  are diagrams each illustrating the sequence of transmission of a communication data string according to the fourth exemplary embodiment.  
      In the sequence illustrated in  FIG. 11 , a specific command (1 byte)  1100  from the virtual system  230  is used as a synchronization command, and when receiving the synchronization command, the television lens  190  immediately transmits a communication data string  1110 . Accordingly, as the synchronization command  1100  is received from the virtual system  230  at intervals of a video synchronization period (vertical synchronization period  1120 ), the communication data string  1110  synchronized with the video synchronization period  1120  is transmitted from the television lens  190 . Transmitting such a stylized data string from the television lens  190  enables the television lens  190  to be reliably connected to the virtual system  230 . Accordingly, an image synthesis system having good responsivity and synchronized with a video signal can be established without modifying the configuration of the television lens  190 .  
      In the sequence illustrated in  FIG. 12 , the television lens  190  receives a vertical synchronization signal  1200  in place of the synchronization command transmitted from the virtual system  230 . In this case, a similar effect as that in the sequence shown in  FIG. 11  can be obtained.  
      As described above, a television lens can include a movable optical member (e.g., a zoom lens, a focus lens, an iris mechanism, or an extender); a position detection unit configured to detect the position of the movable optical member; and a control unit configured to recognize position detection information obtained by the position detection unit and to perform driving control of the movable optical member and communication with a command instruction unit for a user. The television lens further can includes a signal input/output unit for image synthesis. The signal input/output unit can have three transmission methods, including a first transmission method which can use an analog voltage signal, a second transmission method which can use a digital pulse train, and a third transmission method which can use data communication from the control unit. The signal input/output unit can be used for a virtual system. Accordingly, in at least one exemplary embodiment, the television lens can be configured to connect with the virtual system even if any of the first, second, and third transmission methods is requested by the virtual system. Thus, in accordance with such an exemplary embodiment, an image synthesis system can be established without modifying the configuration of the television lens.  
      In addition, data transmitted by the signal input/output unit for image synthesis can include relative position data on the zoom lens, the focus lens, the iris mechanism, the extender, or other optical elements. Accordingly, even if the virtual system does not possess optical data inherent in the television lens, in at least one exemplary embodiment the television lens can be connected to the virtual system. Thus, in accordance with such an exemplary embodiment, an image synthesis system can be established without modifying the configuration of the television lens.  
      In addition, the television lens can further include a storage unit storing optical data inherent in the television lens. The television lens can create new optical data as transmission data by using position information (e.g., on the zoom lens, the focus lens, the iris mechanism, the extender, or other optical element), an arithmetic program, and an arithmetic processing unit. The optical data can be at least one of an angle of view, a principal point, an object distance, a focal length, a depth of field, a depth of focus, and an iris F-number that vary in association with driving of the zoom lens, the focus lens, the iris mechanism, the extender, or other optical element. Optical data stored in the television lens facilitates new optical data associated with the driven position of the zoom lens, the focus lens, the iris mechanism, the extender, or other optical elements to be calculated and transmitted to the virtual system. Accordingly, the need for the virtual system to possess data inherent in the television lens and to calculate optical position data for image synthesis is reduced. Thus, in accordance with such an exemplary embodiment, an image synthesis system can be established without modifying the configuration of the television lens. In addition, since the need for calculation in the virtual system is reduced, an image synthesis system having good responsivity can be configured.  
      In addition, in accordance with at least one exemplary embodiment the television lens can further include a data structure selection setting unit configured to select and set a data structure of transmission data transmitted by the signal input/output unit for image synthesis. Accordingly, in such an exemplary embodiment a data structure, corresponding to data for the virtual system, can be obtained, and an image synthesis system can be established without modifying the configuration of the television lens. In addition, since data for the virtual system can be efficiently transmitted, the performance of the image synthesis system can be improved.  
      In addition, transmission data transmitted by the signal input/output unit for image synthesis can be transmitted in synchronization with specific received data or a specific input signal. Accordingly, when a specific command is received from the image synthesis system in synchronization with a video signal, or when a specific input signal is received, the television lens can transmit data to the virtual system. Thus, an image synthesis system that is synchronized with a video signal can be established without modifying the configuration of the television lens.  
      Furthermore, data communication between the television lens and the virtual system may be performed by wireless communication or by wired communication.  
      Furthermore, command data strings described in the above embodiments are shown only as examples. Additional commands, such as an end command or a frame check sequence, may be omitted.  
      In at least one exemplary embodiment, optical information that is recognizable by a virtual system is created in a lens apparatus. Thus, an image synthesis system can be provided with a reduced need to change optical information stored in the virtual system if lens apparatuses are exchanged.  
      While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures and functions.  
      This application claims priority from Japanese Patent Application No. 2004-210111 filed Jul. 16, 2004, which is hereby incorporated by reference herein in its entirety and claims priority under 35 USC § 120 to co-pending application Ser. No. 11/103,029 filed 11 Apr. 2005 in the United States Patent and Trademark Office.