Interchangeable lens type camera apparatus

Abstract: This invention discloses an interchangeable lens type video camera for deciding lens specifications on a camera side (2) and changing control data transmitted from the camera side to a lens unit (1) in accordance with specifications of the lens unit (1), thereby performing optimal control. A video camera (2) is also disclosed in which an adapter for mounting a lens unit (1) on the video camera is arranged, and control data output from the video camera side to the lens unit (1) is corrected in accordance with lens characteristics, thereby performing the same operation as in a case wherein a video camera lens is mounted on the video camera.

Description: The present invention relates to a lens-interchangeable video camera apparatus. Interchangeable lenses have been conventionally used in the field of cameras, and appropriate lenses can be selected in accordance with photographic conditions and applications. As another tendency, various functions such as focus control, exposure control, and zoom control, all of which are required to operate a camera, are automated to improve operability. These automatic functions must be equipped as standard functions. The recent developments in video equipment such as a video camera and an electronic still camera have been remarkable. Interchangeable lenses which have been conventionally used in only sliver-chloride film cameras except for some special equipment are proposed to be used in video cameras. Optimal lens units can be selected in accordance with photographic conditions and applications, and the range of use of video cameras can be remarkably increased. When interchangeable lenses are to be used in video cameras, video camera interchangeable lenses must be newly designed. However, demand may have arisen for use/connect interchangeable lenses for silver chloride film cameras in/to video cameras. It is therefore expected that an adapter or converting device for connecting any lens unit to a video camera be necessary. In an interchangeable lens type camera unit of this type, a control signal is sent from a camera side to a lens unit side to control each drive system in the lens unit. For example, no problem occurs when a still camera lens unit is mounted on the camera body to perform a manual operation. However, when automatic control is to be performed from the camera side, a system cannot perform a normal auto focus operation even if the system mounted with the still camera lens unit is to be controlled as in a system mounted with a video interchangeable lens system due to the following reasons. A focus encoder may not be arranged. Even if it is arranged, the encoder area divisions are not equal to those of the video lens unit. A focus ring cannot be stopped at an optimal position even if the focus ring is controlled to be stopped at a boundary of divisions of the encoder. When interchangeable lenses are to be mounted on video cameras and a lens unit (e.g., an existing still camera lens unit) having standards different from those of a video camera lens unit is to be connected to a video camera, an adapter is required to connect a lens unit for a silver chloride film camera to a video camera because mounts for the still and video cameras are different from each other and various differences caused by still image photography and moving image photography are present in operation and control systems. In connection of an existing still camera lens unit to a video camera through an adapter or converting device, since design and specifications of the video camera lens are different from those of the still camera lens unit, data cannot be directly exchanged between the video camera and the mounted lens unit. For example, in an auto focus operation, an appropriate auto focus speed cannot be selected. More specifically, a stable auto focus operation cannot be performed in lenses having different image variable magnification factors corresponding to a movement of a distance ring unless a control speed is set variable. For example, at a nearly focused position, hunting occurs to largely change an image angle in a lens having a large image variable magnification factor as in a video camera lens unless a focus speed is controlled to be reduced. On the other hand, in a lens having a small image variable magnification factor as in a still camera lens, a change in image angle is small even if hunting occurs because the focus speed is controlled to be relatively high. However, if the focus speed is controlled as in the video camera lens, the focus speed is too low in the still camera lens although it is appropriate for the video camera lens. Since the shortest range photographic distances of the video camera lens unit and the still camera lens unit are different from each other, a period required for shifting the state from a much unfocused state to a nearly focused state in the video camera lens unit is largely different from that in the still camera lens. Appropriate control cannot be performed when a still camera lens unit is simply connected to a video camera unit. Document EP-A-0 352 778 discloses an automatic focus adjusting device in a video camera system comprising a focus detecting circuit, a control circuit generating a control signal for the lens in response to the focus detecting signal and a characteristic detecting circuit for detecting the optical characteristic of the lens. In this camera system the lens unit and the camera body both have the same format of the control signal. In particular, the camera body recognizes the characteristics of the lens unit by an initial communication and inhibits to transmit a control command which is not supported by the characteristics of the lens unit, to the lens unit. Furthermore, document US-A-4 518 239 discloses an intermediate adapter for a camera for coupling an interchangeable lens and a camera body of different flange focal distances. By means of this adapter connection between a video camera and the lens of a still camera can be attained. In particular, the adapter comprises an aperture value transmitting member and an aperture device replacing a stop of the interchangeable lens. An aperture opening degree regulator is used to setting the aperture opening according to aperture data transmitted. Furthermore, a video changeover device is provided which releases the aperture opening degree regulator to allow the aperture device to operate in a range of a fully open state to a fully closed state. By means of this adapter it is possible, in case of use of a lens for a single-lens reflex camera with a video camera, to perform motion picture photographing operations in an automatic aperture control mode and still photographing operations in a preset automatic aperture control mode. That is, the intermediate adapter performs aperture correction caused by differences of flange focal distances, i.e. performs iris control. Moreover, document EP-A-0 482 640, which falls within the term of Art. 54(3) EPC, discloses a video camera on which a lens unit of a still camera can be mounted via an adapter device that converts an iris control signal. This adapter comprises a signal conversion circuit for converting an automatic exposure control signal generated from the output of a video signal processing circuit of a video camera into an automatic exposure control signal generated from the output of a video signal processing circuit for converting an automatic exposure control signal for an interchangeable lens system for a still camera. EP-A-0 357 056 discloses a camera system, wherein on a camera main body having focus adjusting means a photographic lens can be detachably mounted, the photographic lens including a diaphragm adjusting mechanism and an autofocus means. The user of the camera can select on both the camera body and the photographic lens the operation mode of the autofocus means, i.e. whether an automatic focusing is performed or whether the user must provide a manual focusing of the object to be photographed. A setting switch is provided respectively on the photographic lens and the camera main body by means of which the autofocus mode or the manual focusing mode can be selected. In order to avoid conflicting setting of the autofocus mode a control means in the camera main body senses the operation state of the respective switches in the photographic lens and the camera main body and allows performance of an autofocus mode of the autofocus means. only if both switches are set to the same operation condition indicating the autofocus mode. If at least one of the switches is set to the manual focusing mode, i.e. when on the photographic lens and on the camera main body, respectively, the mode switch is switched off, a manual focusing will be performed. The present invention has been made in consideration of the above conventional problems, and has as its object to provide an interchangeable lens type video camera apparatus capable of always and optimally controlling a plurality of lens units having different standards and functions without causing operation errors and degradation of accuracy. This object is accomplished by a lens-interchangeable video camera apparatus according to the appended claims. The above and other objects, features, and advantages of the present invention will be apparent from the following detailed description in conjunction with the accompanying drawings, of which Fig. 1 is a block diagram showing an arrangement of an interchangeable lens type camera system according to a first embodiment of the present invention; Figs. 2A and 2B are a timing chart showing a communication format in the interchangeable lens type camera system and a view showing a data format of control data transmitted from the lens side to the camera side, respectively; Fig. 3 is a flow chart showing a control operation of a camera microcomputer in a camera body in Fig. 1; Fig. 4 is a flow chart showing a control operation of a lens microcomputer in Fig. 1; Figs. 5A to 5D are views for explaining display contents in a focus mode on the camera side; Fig. 6 is a block diagram showing another interchangeable type camera system; Fig. 7 is a block diagram showing another interchangeable lens type camera system; Figs. 8A and 8B are a timing chart showing a communication format in the interchangeable lens type camera system and a view showing a data format of control data transmitted from a camera body to a lens unit, respectively; Fig. 9 is a flow chart showing a control operation of a camera microcomputer in the camera body; Fig. 10 is a flow chart showing a control operation of a lens microcomputer in Fig. 6; Fig. 11 is a flow chart showing a control operation of a lens microcomputer in Fig. 7; and Figs. 12A and 12B are views showing iris operation control patterns in Figs. 6 and 7. An interchangeable lens type camera system according to the preferred embodiment of the present invention will be described with reference to the accompanying drawings. A video camera apparatus free from operation errors even if identical functions or operation units are present in both a lens unit and a camera body or camera unit will be described according to an embodiment of the present invention. More specifically, in the interchangeable lens type video camera apparatus, an auto focus control function (AF) as one of the functions of the video camera will be exemplified. A mode display representing an AF operation mode or a manual focus mode, and various display contents such as a focus detection area are displayed on the screen of an electronic viewfinder. These display operations can be performed in the interchangeable lens type video camera system by deciding whether control data communication between the lens unit and the camera body is normally performed, or by an ON/OFF state of a lens ON/OFF detection switch. When interchangeable lens units can be mounted on a video camera body, these lens units have different specifications. If a switch for enabling/disabling the AF function is arranged on only the camera body side, no problem occurs. Assuming that a switch for enabling/disabling the AF function on the lens unit side is also arranged in the lens unit, the AF operation mode is undesirably set such that the AF function ON/OFF switch on the camera body side is kept on although the AF switch on the lens unit is kept off. The actual display content may be different from an actual operation state, thereby degrading operability and causing operation errors. Therefore, the operator is confused with the operations and display contents. An auto exposure control function (auto iris control) will be exemplified. In a conventional video camera body, an auto iris ON/OFF switch may also be arranged on the camera body side, and the ON/OFF operation of auto iris control is performed on the camera body side. An auto iris ON/OFF switch may also be arranged on the lens unit side. In this case, since the auto iris ON/OFF switch is also arranged on the camera body side, the operator cannot decide which switch is effective for auto iris ON/OFF control and is confused with key operations, thus causing operation errors. In addition, optimal diaphragm control becomes time-consuming during photography, and an important shutter change may be missed, thus posing problems in terms of operability, reliability, and safety. When even if switches for enabling/disabling the auto focus functions are independently arranged on the lens unit and camera body sides, the operation state on the lens unit side can be detected on the camera body side, and appropriate operation and display control free from a difference between the operation state on the camera body side and that on the lens unit side can be performed. The operation result of the auto iris ON/OFF switch on the lens unit side is read by the camera body. Auto iris control is performed when a logical AND product of the read result and an output result of an auto iris ON/OFF switch of the camera body is obtained, i.e., when both the control switches are set in ON state. Auto iris control is performed by only the lens auto iris ON/OFF switch having better operability than the camera auto iris ON/OFF switch while the camera auto iris ON/OFF switch is kept on. The embodiment will be described first with reference to Figs. 1 to 5D. Referring to Fig. 1, a lens unit LS and a camera body CM are connected through a mount unit M. An object to be photographed is represented by reference numeral 100. The lens unit LS includes a focusing lens 401, a zoom lens 402, a diaphragm (iris diaphragm) 403, a relay lens 404, a focus encoder 405 for detecting a position of the focusing lens 401, a zoom encoder 406 for detecting a movement position, i.e., a focal length of the zoom lens 402, a diaphragm encoder 407 for detecting an F-number of the diaphragm 403, a focus driver 408 including a motor for driving the focusing lens 401, a zoom driver 409 including a zoom motor for driving the zoom lens 402, an iris driver 410 including an IG meter and a motor for driving the diaphragm 403, a lens control microcomputer (to be referred to as a lens microcomputer hereinafter) 411 for controlling the respective drivers on the basis of control data transmitted from the camera body side to systematically control the lenses and the diaphragm, and a focus mode switch 412 for setting an ON/OFF state of an auto focus control operation (AF) on the lens unit side. An operation status signal of this switch is fetched by the lens microcomputer 411 and is transmitted to the camera body side in accordance with a predetermined format. A communication line 422 exchanges various control data with the camera body side. The camera body CM includes an image pickup element 413, a preamplifier 414, a process circuit 415, a band pass filter 416, a gate circuit 417, a peak hold circuit 418, a camera control microcomputer (to be referred to as a camera microcomputer hereinafter) 419, and a focus mode switch 420. The image pickup element 413 such as a CCD photoelectrically converts an object image focused by the lens unit LS connected thereto and outputs an image pickup signal. The preamplifier 414 amplifies the image pickup signal output from the image pickup element 413 to a predetermined level. The process circuit 415 performs signal processing (e.g., gamma correction, blanking processing, addition of a sync signal) of the image pickup signal output from the preamplifier 414 and outputting a standardized television signal such as an NTSC television signal. The BPF 416 extracts a high-frequency component of a luminance signal which changes in accordance with a degree of a focus state from the image pickup signal. The gate circuit 417 gates the high-frequency signal output from the BPF 416 to set a focus or focused state detection area (distance measuring area) set within the image pickup surface and causes to pass only a signal corresponding to the area. The peak hold circuit 418 detects a peak value of the high-frequency signal (within the focus detection area) having passed through the gate circuit 417 within a one-field period. The camera microcomputer 419 receives the peak value of each field output from the peak hold circuit 418, calculates a speed and a drive direction to drive the focusing lens 401 in a direction to maximize the peak value, and outputs the calculated speed and drive direction to the lens unit side. The camera microcomputer 419 also supplies control data corresponding to exposure control and operations of a zoom operation switch, thereby systematically controlling the camera body CM and the lens unit LS. The focus mode switch 420 is operated such that the auto focus control (AF) is set in an ON/OFF (auto/manual) state. The operation status signal of this switch is fetched by the camera microcomputer 419 and controls AF control data to be transmitted to the lens unit side. An electronic viewfinder 421 reproduces a video signal output from the process circuit 415 and displays it. An AF display circuit 422 displays an ON/OFF (auto focus/manual focus) state of the AF operation on the screen of the electronic viewfinder 421. Figs. 2A and 2B show a control data communication timing and a data format in control data communication performed between the camera body CM and the lens unit LS through the communication line 422. In this control data communication, various control data and status data are transmitted and received in the illustrated format. The focus driver 408, the zoom driver 409, and the iris driver 410 in the lens unit LS are controlled. Referring to Fig. 2A, a ready signal SRDY is a chip select signal output from the camera microcomputer 419 and indicates to start communication with the lens unit LS. A signal SCLK is a serial clock signal output from the camera body CM, and data communication is performed in accordance with this clock period. Data TXD is data transmitted from the lens microcomputer 411 in the lens unit LS to the camera microcomputer 420 in the camera body CM. This communication is performed by several words. The data format of the data RXD is shown in Fig. 2 B. The data RXD is constituted by a predetermined number of words each consisting of eight bits. It is important that one bit as the fourth bit from the MSB of the Xth word serves as an focus auto function OFF bit (to be referred to as a focus bit) for representing the ON/OFF state of the focus mode switch 11 on the lens unit side, i.e., representing whether the auto focus mode or the manual focus mode is set. When the focus mode switch 412 on the lens unit side is set in the ON (AF mode) state, the focus bit is set to be "0". However, when the focus mode switch 412 on the lens unit side is set in the OFF (manual mode) state, the bit is set at "1". A control operation of the camera microcomputer 420 shown in Fig. 1 will be described with reference to a flow chart in Fig. 3. Referring to Fig. 3, when the flow is started, it is discriminated in step 141 whether communication performed with the lens microcomputer 411 is initial communication for fetching initial data from the lens unit LS. If this communication is discriminated to be initial communication, the flow immediately advances to step 145 to communicate with the lens microcomputer 411. A request is transmitted from the camera body side to the lens unit side, and response data is received from the lens unit side. The operations insteps 141, 145, and 146 are repetitively performed until the initial communication is completed. If the initial communication is completed, various data received from the lens unit side are analyzed in step 147. If the communication to be performed in step 141 is not the initial communication, i.e., if the initial communication has been completed, the flow advances to step 142. The focus bit representing the state of the focus mode switch in the data RXD from the lens unit side is checked. If the focus bit is set at "1", i.e., if the focus mode switch 412 on the lens unit side is set in the OFF state, i.e., the manual focus mode, the flow advances to step 143, and the focusing lens 401 is stopped to set a stop command in the focus control command so as to stop the AF operation. The flow advances to step 144 to cause the electronic viewfinder on the camera body side to display that the AF function is set in the OFF state. The flow then advances to step 145 to perform control data communication with the lens unit LS. The data received from the lens unit side in step 146 is analyzed, and the flow returns to step 141. If the focus bit is set to be "0" in step 142, i.e., if the focus mode switch 412 on the lens unit side is kept in the ON state, i.e., the AF mode, the flow advances to step 147 to detect the ON/OFF state of the focus mode switch 420 on the camera body side. If the ON state is detected, i.e., if the AF operation is set, the flow advances to step 148 to execute the AF routine. In the AF routine, the peak value output at the field period from the peak hold circuit 418 on the camera body side is fetched by the camera microcomputer 419. The control data representing the speed and direction for driving the focusing lens 401 in a direction to maximize the peak value is calculated, and the focus control command is output. After the AF mode is displayed on the electronic viewfinder 421 in step 149, the flow advances to step 145 to transmit the calculated focus control command to the lens unit side. In step 146, the status data sent back from the lens unit LS in response to the control data transmitted from the camera body side is analyzed, and the flow returns to step 141. When the focus mode switch 420 on the camera body side is set in the OFF state in step 147, the flow advances to step 150 to set a focus stop command for stopping the focusing lens 401 and then the AF operation. In step 151, the AF mode display is disabled, and the flow advances to a routine for performing communication with the lens unit LS in step 145. In the above embodiment, the lens focus mode switch 412 has a priority to perform an ON/OFF operation of the AF mode and an ON/OFF operation of the AF display. Even if the focus mode switch 420 on the camera body side is kept in the ON state, the AF operation and the AF display are disabled in the OFF state of the focus mode switch 412 on the lens unit side. The AF operation and the AF display can be switched in accordance with only the operation of the focusing mode switch 420 on the camera body side. The operator will not be confused with the operations and displays, thereby providing an efficient system almost free from operation errors. An operation of the lens microcomputer 411 will be described with reference to a flow chart in Fig. 4. Referring to Fig. 4, when the flow is started, serial communication with the camera body side is performed in step 161. Various control data calculated on the camera body side are received. In step 162, the control data received from the camera body side are analyzed. In step 163, the ON/OFF state of the focus mode switch 412 on the lens unit side is checked. If the focus mode switch 412 on the lens unit side is set in the ON state, the flow advances to step 164 to drive the focusing lens 401 in accordance with the focus control data sent from the camera body side, and the flow returns to step 161. If the focus mode switch 412 on the lens unit side is set in the OFF state in step 163, the flow advances to step 165. In order to transmit to camera body side that the AF operation mode is set in the OFF state , i.e., the manual focus mode is selected on the lens unit side, the focus bit is set at "1". In step 166, the focusing lens 401 is stopped, and the flow returns to step 161. In serial communication with the camera body side in step 161, the focus bit of "1", i.e., the AF-OFF state on the lens unit side is transmitted to the camera body side. The flow charts in Figs. 3 and 4 are repeatedly performed every vertical sync signal. Figs. 5A to 5D are views for explaining display contents of the AF-ON/OFF operation state on the camera body side. The focus mode is displayed on the screen of the electronic viewfinder. As is apparent from Figs. 5A to 5D taken together with the system configuration of Fig. 1, the ON/OFF state of the focus mode switch 412 on the lens unit side is transmitted as bit data to the camera microcomputer 419 through communication with thecamera body side. When the camera microcomputer 419 discriminates that one of the focus mode switch 412 on the lens unit side and the focus mode switch 420 on the camera body side is set in the AF-OFF state, i.e., the manual focus mode, the camera microcomputer 419 controls the AF display circuit 422 to switch the display content from the content representing the AF state to the content representing the manual state. As shown in Figs. 5A to 5D, in the AF-ON mode, the "focused state detection area (distance measurement frame)" (Fig. 5A) is presented to the operator, so that the operator can recognize that the AF mode is set. If the AF-OFF mode is set, i.e., the manual mode is selected, the "focused state detection area (distance measurement frame)" is erased from the screen as shown in Fig. 5C, so that the operator can know the AF mode is not set. As shown in Fig. 5B, in the AF-ON mode, i.e., in the auto focus mode, "AF" is displayed on the screen of the electronic viewfinder. As shown in Fig. 5D, in the AF-OFF mode, i.e., the manual mode, "M" is displayed on the screen of the electronic viewfinder, thereby eliminating unnatural display contents. With the above arrangement, when the focus mode switch is arranged on the lens unit side, i.e., the focus mode switches are arranged on both the camera body and lens unit sides, the AF display contents can be switched in accordance with the set operation mode. Therefore, unnatural display operation in which "AF" is kept displayed although the focus mode selection switch on the lens unit side is turned off can be prevented. As described above, in the interchangeable lens type camera system according to the present invention, the operation state of the focus mode selection switch on the lens unit LS is read by the camera body CM, and the read result is compared with the operation state of the focus mode selection switch on the camera body side. The focus mode and its display are selected in accordance with the operation states of these switches. When the focus mode switch on the lens unit side is set in the ON state (AF mode), the focus mode is determined by the focus mode switch on the camera body side. If the focus mode switch on the lens unit side is kept in the OFF state, the AF-OFF mode, i.e., the manual mode is set regardless of the operation state of the focus mode switch on the camera body CM. Therefore, when both the focus mode switches are set in the ON state, auto focus control is performed. Therefore, even if the focus mode selection switches are arranged on both the lens unit and camera body sides, the operator is not confused with the operations. Focus control and display operations free from operation errors with excellent operability can always be performed. Another interchangeable lens type camera system will be described with reference to Fig. 6. The same reference numerals as in Fig. 1 denote the same parts in Fig. 6, and a detailed description thereof will be omitted. A lens unit includes a lens control microcomputer (to be referred to as a lens microcomputer hereinafter) 511 for controlling respective drives on the lens unit side on the basis of control data transmitted from the camera body or camera unit side and systematically controlling respective lenses and a diaphragm, and an auto iris ON/OFF switch 512 for automatically controlling a diaphragm (iris diaphragm) 403 on the lens unit side on the basis of the data from the camera body side (when this switch is set in the OFF state, the manual mode is set). An operation state of this switch is fetched by the lens microcomputer 511 and is transmitted to the camera body side in accordance with a predetermined format. A communication line 522 exchanges various control data with the camera body side. A camera unit or camera body, respectively includes an auto iris control circuit (AE circuit) for comparing a luminance level of an image pickup signal output from a preamplifier 414 with a predetermined reference level Vref and outputting a signal corresponding to a difference therebetween. A camera control microcomputer (to be referred to as a camera microcomputer hereinafter) 520 receives a peak value of each field output from a peak hold circuit 418, calculates a speed and a drive direction for driving a focusing lens 401 in a direction to maximize the peak value, and outputs the calculated results to the lens unit side. The camera microcomputer 520 receives an output signal from the AE circuit 519, calculates a diaphragm control signal for controlling the diaphragm so that the luminance level of the image pickup signal is always set equal to the reference level Vref, and outputs the calculated diaphragm control signal to the lens unit side, thereby systematically controlling the camera body and the lens unit. An auto iris ON/OFF switch 521 automatically controls an auto iris control mode in response to an output from the AE circuit 519 so as to ON/OFF-control the diaphragm on the lens unit side (when this switch is set in the OFF state, the manual mode is set). An operation state of this switch is fetched by the camera microcomputer 520. Fig. 7 shows an arrangement in which a lens unit having no auto iris ON/OFF switch is connected to a camera unit or camera body respectively. The arrangement in Fig. 7 is different from that in Fig. 6 in that the auto iris ON/OFF switch is arranged or not arranged on the lens unit side. Therefore, although the arrangement in Fig. 7 is illustrated, a detailed description thereof will be omitted. Figs. 8A and 8B show a control data communication timing and a data format in control data communication performed between a camera body CM and a lens unit LS through a communication line 522. Various control data and various status data are transmitted and received in the illustrated format. A focus driver 408, a zoom driver 409, and an iris driver 410 in the lens unit LS are controlled. Referring to Fig. 8A, a signal SRDY is a chip select signal for performing communication with the lens unit LS. A signal SCLK is a serial clock signal output from the camera body CM. Data RXD is data transmitted from the lens microcomputer 511 in the lens unit LS to the camera microcomputer 520 in the camera body CM. Data TXD is data transmitted from the camera body CM to the lens unit LS. Fig. 8B shows a data format of the control data RXD (Fig. 8A) transmitted from the lens unit LS to the camera body CM. It is important that one bit as the fourth bit from the MSB of the Xth word is set as an auto iris function OFF bit representing an operation state of the auto iris ON/OFF switch in the lens unit LS. The camera body side decodes the control data transmitted from the lens unit side and checks the state of the auto iris OFF bit, thereby deciding whether the lens unit LS is set in the auto iris control state (i.e., the operative state of the auto iris ON/OFF switch). A control operation of the camera microcomputer 520 shown in Figs. 6 and 7 will be described with reference to a flow chart in Fig. 9. Referring to Fig. 9, the flow is started, various control data are transmitted to the lens microcomputer 511 through the communication line 522 in step 171. The data as a result of communication with the lens microcomputer 511 are analyzed in step 172. It is then decided in step 173 whether initial communication is to be performed to fetch initial data from the lens microcomputer 511 and hence the lens unit LS. If the power ON state is set, or the initial communication has been performed upon mounting of a lens unit LS and various control data and status data in response to these control data have been already exchanged, the flow advances to step 174. When initial communication is to be performed, the flow returns to steps 171 to transmit various control data to the lens microcomputer 511. Otherwise, the flow advances to step 174 to discriminate whether the auto iris OFF bit in the control information sent from the lens unit side through the above communication is set to be "1". If YES in step 174, the auto iris ON/OFF switch 512 on the lens unit side has been set in the OFF state, i.e., the manual mode. The flow advances to step 175 to set an iris stop command. A manual iris control mode is displayed in step 176, and the flow advances to step 171 to transmit the iris stop command to the lens unit side. When the auto iris function OFF bit is not set at "1" in step 174, the auto iris ON/OFF switch 512 on the lens unit side has been set in the ON state, i.e., the auto iris control mode has been set. In this case, the flow advances to step 177 to check the operation state of the auto iris ON/OFF switch 521 on the camera body side. If the auto iris ON/OFF switch 521 on the camera body side is set in the ON state in step 177, that is, if both the auto iris ON/OFF switches on the lens unit and camera body sides are kept in the ON state, the flow advances to step 178. In this step, the camera microcomputer 520 calculates iris control data in accordance with output data from the AE circuit 519. An auto iris control mode is displayed in step 179, and the flow returns to step 171 to transmit the iris control data to the lens unit side. When the auto iris ON/OFF switch 521 on the camera body side is not set in the ON state in step 177, the flow advances to step 180 to set a manual iris control mode. This manual iris control mode is displayed in step 181, and the flow advances to step 171 to transmit the iris stop command to the lens unit side, thereby controlling the iris diaphragm 403 manually. As described above, the camera microcomputer 520 discriminates whether the auto iris function OFF bit sent from the lens microcomputer 511 is set at "0" or "1". If this bit is set at "0", i.e., if the auto iris ON/OFF switch on the lens unit side is set in the ON state, iris control is performed in accordance with the operation state of the auto iris ON/OFF switch on the camera body side. If the above bit is set at "1", i.e., if the auto iris function ON/OFF switch on the lens unit side is set in the OFF state, a stop command is set as the iris control command and is transmitted to the lens microcomputer 511. It is very important that iris control in the camera body CM is set in the auto iris mode, and that if the auto iris function OFF bit is set at "0", the camera microcomputer 520 performs auto iris control. That is, when auto iris ON/OFF switches on the camera body and lens unit sides are set in the ON state, auto iris control is performed. When one of the switches is set in the auto iris control OFF state, auto iris control is not performed. A control operation of the lens microcomputer 511 will be described with reference to a flow chart in Fig. 10. Referring to Fig. 10, when the flow is started, various control data are received from the camera microcomputer 520 through the communication line 522 in step 191. The data as a result of communication with the camera body side are analyzed in step 192. An operation state of the auto iris ON/OFF switch 512 on the lens unit side is checked in step 193. If this switch is set in the ON state, the flow advances to step 194 to set the auto iris function OFF bit to be "0". The iris driver 510 is driven and controlled in accordance with the iris control data transmitted from the camera microcomputer 520 in step 195, thereby controlling the diaphragm (iris diaphragm) 403. In step 193, when the auto iris ON/OFF switch 512 on the lens unit side is set in the OFF state, the flow advances to step 196 to set the auto iris function OFF bit to be "1". In step 197, iris driving is stopped in step 197, and the manual mode is set. Referring to Fig. 10, if the auto iris ON/OFF switch 512 on the lens unit side outputs an iris ON signal to the lens microcomputer 511, the lens microcomputer . 511 sets the auto iris function OFF bit to be "0". Iris drive control is performed in accordance with the iris control data transmitted from the camera microcomputer 520. If the above switch is set in the OFF state, the lens microcomputer 511 sets the auto iris function OFF bit to be "1", thereby stopping the iris diaphragm 403. It is important that if the auto iris ON/OFF switch 512 is set in the OFF state, i.e., the auto iris function is set in the OFF state on the lens unit side, the auto iris function OFF bit is set at "1" to inform the camera body side of the auto iris function OFF state of the lens unit side. When the auto iris ON/OFF switch is arranged in the lens unit side, the iris diaphragm 403 is operated by a combination with the camera body CM, as shown in Fig. 12A. That is, only when both the auto iris ON states on the lens unit and camera body sides are obtained, auto iris control is performed. Fig. 11 is a flow chart on the lens unit side when a lens unit having no auto iris ON/OFF switch is used as shown in Fig. 7. Referring to Fig. 11, when the flow is started, the lens microcomputer 511 communicates with the camera microcomputer 520 in step 201. The communication data transmitted from the camera microcomputer 520 are analyzed in step 202. In step 203, the auto iris function OFF bit is set to be "0". The same data as in the ON state of the auto iris ON/OFF switch is transmitted to the camera microcomputer 520. As is apparent from the above embodiment, the iris diaphragm 403 can be set in a controllable state on the basis of the control data from the camera microcomputer 520. In practise, the iris diaphragm 403 is driven in accordance with the iris control data from the camera body CM in step 204. As described above, since the auto iris ON/OFF switch is not arranged on the lens unit side, the auto iris function OFF bit is always set to be "0" and is sent back to the camera body CM, so that iris control is performed on the basis of the control data from the camera microcomputer 520, i.e., the auto iris ON/OFF switch from the camera body side, thereby performing smooth iris control free from operation errors. The iris operations performed when the lens unit LS is connected to the camera body CM are summarized, as shown in Fig. 12B. As has been described above, there is provided a video camera capable of causing a camera body CM to read an operation result of an auto iris ON/OFF switch of a lens unit LS, performing auto iris control when a logical AND product of the read result and an output result of an auto iris ON/OFF switch of the camera body CM is obtained, i.e., when both the control switches are set in the ON state, performing auto iris control by only the lens auto iris ON/OFF switch having better operability than the camera auto iris ON/OFF switch while the camera auto iris ON/OFF switch is kept on. Just to sum up, it can be said that the application discloses an interchangeable lens type video camera for deciding lens specifications on a camera body side and changing control data transmitted from the camera body side to a lens unit in accordance with specifications of the lens unit, thereby performing optimal control. A video camera is also disclosed in which an adapter or converting device, respectively, for mounting a lens unit on the video camera body is arranged, and control data output from the video camera body side to the lens unit is corrected in accordance with lens characteristics, thereby performing the same operation as in a case wherein a video camera lens unit is mounted on the video camera body.

Claims: A lens-interchangeable video camera system having a camera unit (CM) and a lens unit (LS) detachably mountable on the camera unit, comprising: communicating means for communicating information between said camera unit and said lens unit; lens mode setting means (412; 512), arranged in said lens unit, for setting an operation mode of driving means (408) relative to a focus operation in said lens unit; first detecting means for detecting the operation mode set by said lens operating means on the basis of information transmitted through said communicating means; camera mode setting means (420; 521), arranged in said camera unit, for setting an operation mode of driving means (408) relative to the focus operation (408) in said lens unit; second detecting means for detecting the operation mode set by said camera operating means; display means (422), arranged in said camera unit, for displaying on an image screen an image picked up by said camera unit and said lens unit and the operation mode of said driving means (408); control means (419) for determining the operation mode of said driving means (408, 410) on the basis of said camera operating means and said lens operating means, for setting said driving means in the automatic operation mode in the case that said first and second operation mode detecting means detect that said lens mode setting means and said camera mode setting means are set in an automatic operation mode, and controlling said display means (422) to display the automatic operation mode by displaying a focus detecting area, on said image screen, and for setting said driving means in the manual operation mode in the case that at least one of said lens mode setting means and camera mode setting means is not set in the automatic operation mode, and controlling said display means (422) to display the manual operation mode by erasing the focus detecting area from the image screen. A lens-interchangeable video camera system according to claim 1, characterized by said lens mode setting means (412) and said camera mode setting means (420) setting ON/OFF of an automatic control of said driving means (408) and said control means (419; 520) controlling said display means to display ON/OFF state of said automatic control of said driving means. A lens-interchangeable video camera system according to claim 1 or 2, characterized by said driving means (408) driving an autofocus lens (401) and said control means performs an automatic focusing operation. A camera unit used in the camera system recited in any one of claims 1 to 3, the camera unit having the camera-side features of claims 1 to 3.

Inventors: IIJIMA RYUNOSUKE, MABUCHI TOSHIAKI, OHTA SEIYA, IIJIMA, RYUNOSUKE, MABUCHI, TOSHIAKI, OHTA, SEIYA
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1992
Main classification: H04N5
IPC codes: H04N5