JP5661335B2 - Camera system, interchangeable lens, and camera body - Google Patents

Description

The present invention relates to a camera system, an interchangeable lens, and a camera body.

  Conventionally, in a single-lens reflex camera, a film exchange type is generally used, but in recent years, a digital type using an electronic image pickup device such as a CCD or a CMOS has been adopted. This electronic image sensor has been conventionally used in video cameras, and the system configuration of a digital single-lens reflex camera is similar to that of a video camera. Is possible. Since this digital single-lens reflex camera can shoot moving images, it is required to add a moving image shooting system configuration to the conventional still image shooting system configuration.

  For example, Patent Document 1 discloses a camera system in which a mode, that is, a method of using a communication terminal changes depending on whether or not an adapter is attached between an interchangeable lens and a camera (camera body). . Specifically, the accuracy of autofocus is improved by transmitting an exposure synchronization signal from the camera side to the interchangeable lens side using a dedicated terminal. Here, the exposure synchronization signal generally indicates a vertical synchronization signal (VD), that is, a timing signal at which the electronic imaging device starts exposure. On the other hand, if the camera communicates with the interchangeable lens with a communication specification fixed in advance, unnecessary communication may increase and compatibility may deteriorate. Therefore, Patent Document 2 discloses an imaging method in which an address is added to the content of communication transmitted to the lens unit and communication is performed in synchronization with a vertical synchronization signal.

JP 2008-216439 A Japanese Patent Laid-Open No. 10-65952

  However, in the camera system of Patent Document 1, since a dedicated communication terminal for transmitting the timing at which the electronic image sensor starts exposure to the interchangeable lens is installed, both the camera and the interchangeable lens are expensive. Further, in the imaging method of Patent Document 2, since communication between the camera and the interchangeable lens is synchronized with the vertical synchronization signal, communication can always be performed only at the same timing. For example, even if the user suddenly stops the autofocus operation, even if the user operates the autofocus stop setting of the camera, stop information can be transmitted to the interchangeable lens only at the next exposure timing. That is, since the operation of the device is delayed with respect to the user's instruction, the camera is difficult to operate.

The present invention has been made in view of such a situation, and an object thereof is to provide a camera system that improves the operability of a digital single-lens reflex camera.

In order to solve the above problems, the present invention is a camera system having an interchangeable lens and a camera body, the interchangeable lens having lens control means for controlling the operation of the interchangeable lens and communicating with the camera body , The camera body has camera control means for controlling the operation of the camera body and communicating with the interchangeable lens . The lens control means and the camera control means communicate by an asynchronous communication method, and the lens control means is for camera control. Synchronization control based on the vertical synchronization signal transmitted from the means, and when the camera control means is not communicating between the lens control means and the camera control means, timing information for performing the synchronization control, Transmit to the lens control means at a synchronization timing determined based on the vertical synchronization signal, and communicate between the lens control means and the camera control means at the synchronization timing. If it is done, since the communication is completed, and transmits the timing information including the delay information with respect to the synchronization timing to the lens control unit.

  According to the present invention, the operability of a digital single lens reflex camera is improved.

It is a block diagram which shows the structure of the camera system which concerns on embodiment of this invention. It is a figure which shows the wobbling operation | movement in contrast AF system. It is a conceptual diagram which shows the communication circuit via a contact unit. It is an electric signal figure with respect to the synchronous clock output signal from a camera microcomputer. It is a list of camera commands for asynchronous communication. It is a list of camera commands for synchronous communication. It is a conceptual diagram which shows the synchronous clock output signal from a camera microcomputer. It is a flowchart which shows the interruption process by a lens microcomputer.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(First embodiment)
First, an internal control system of an interchangeable lens and a camera body constituting a camera system according to an embodiment of the present invention (hereinafter referred to as a “communication control device” focusing on a portion related to communication control) will be described. FIG. 1 is a block diagram schematically showing the configuration of the interchangeable lens 1 and the camera body 2 and showing the internal control system. The interchangeable lens 1 is an interchangeable autofocus lens, and includes a focus unit 3, a motor 4, a movement amount detection unit 5, an absolute position detection unit 6, an EEPROM 7, a lens microcomputer 8, and a contact unit 9. First, the focus unit 3 is a holding mechanism for holding the focus lens 10 and focusing the subject so that the focus lens 10 can be moved in the optical axis and horizontal directions. The motor 4 is an actuator for driving the focus unit 3. As the type of the motor 4, a motor such as an electromagnetic type, an ultrasonic type, or a voice coil type can be adopted. In this embodiment, an electromagnetic type is adopted. The movement amount detection unit 5 is detection means for detecting the rotation amount and rotation speed of the motor 4. This movement amount detection unit 5 has a notch formed at the same pitch on the circumference, and includes a disk that rotates in synchronization with the rotation of the motor 4, and the light projected from the LED is a photo interrupter element ( The change of the signal is detected depending on whether it reaches the light receiving element) or is shielded from light. Here, the movement amount detection unit 5 can measure the movement amount of the focus unit 3 because the movement amount of the focus unit 3 is proportional to the rotation amount of the motor 4. The absolute position detection unit 6 is detection means for detecting the absolute position of the focus unit 3. The absolute position detection unit 6 detects a change in signal due to conduction between a plurality of metal brushes moving in conjunction with the focus unit 3 and a fixed metal pattern, and based on the change in signal, The current position is specified. The EEPROM (or flash memory) 7 is a rewritable nonvolatile memory, and the data stored in the EEPROM 7 is adjustment data for the interchangeable lens 1. The lens microcomputer 8 is lens control means for controlling the components in the interchangeable lens 1. The lens microcomputer 8 is equipped with functions such as a communication controller for performing communication with the camera body 2, reset exception processing, A / D, timer, input / output port, ROM, and RAM. The contact unit 9 has a plurality of metal contacts for communicating with the camera body 2 and is a connection means for electrically connecting the lens microcomputer 8 and the camera microcomputer 12. The plurality of metal contacts are composed of a plurality of metal projections installed on the camera body 2 side and a plurality of metal pieces mechanically contacting the metal projections installed on the interchangeable lens 1 side. This metal contact also has a function of supplying power from the camera body 2 to the interchangeable lens 1.

  The camera body 2 is an imaging apparatus body, and includes a distance measuring unit 11, a camera microcomputer 12, and a CCD sensor 13. The distance measuring unit 11 is a measuring means for measuring the amount of deviation on the film surface from the current position of the focus unit 3 with respect to the distance to the subject. In general, an autofocus camera employs a focus shift method using a plurality of line CCDs. In this case, the difference in the contrast (brightness and darkness) of the subject is read and compared with other line CCDs that are previously separated from each other, a shift in the position on the CCD line where the contrast is the same is detected. In other words, in the focused state, the contrast is matched at the same position on the CCD line. In addition, as another distance measuring method, for example, there is a method of performing triangular distance measurement using an infrared light emitting (ILED) body, but the present invention is not particularly limited. The camera microcomputer 12 is a device control unit that controls the components in the camera body 2. The camera microcomputer 12 has functions such as a communication controller for communicating with the lens microcomputer 8, an A / D, a current detector, a timer, a power supply switch to the lens, an input / output port, a ROM, and a RAM. The CCD sensor 13 is an image sensor that converts reflected light from a subject image into an electrical signal. The camera body 2 may have other functions.

  Next, the operation of the communication control apparatus according to this embodiment will be described. First, an autofocus (AF) operation of the imaging apparatus will be described. The camera microcomputer 12 waits until the user gives an instruction to start AF from an unillustrated AF switch, and when there is an instruction, starts the AF operation. Here, the camera body 2 of the present embodiment includes two AF methods, that is, a phase difference detection method and a contrast AF method. First, the phase difference detection method functions when performing still image shooting, which is normal photography, and performs AF operation based on distance measurement data from the distance measurement unit 11. On the other hand, the contrast AF method functions when performing moving image shooting like a video camera, and performs an AF operation by detecting the contrast of a subject. Hereinafter, the communication control apparatus of the present embodiment will be described assuming that it mainly operates during the function of the contrast AF method.

  FIG. 2 is a diagram showing a wobbling operation in which the focus evaluation value is detected by performing minute driving (reverse driving) to the near side and the infinite side in the contrast AF method (or TVAF method). In FIG. 2, a VD signal (vertical synchronization signal) is a synchronization signal that transmits signals of different levels at predetermined time intervals, and in this case, indicates a timing at which charges are accumulated in the CCD sensor 13. The imaging apparatus performs an accumulation operation, that is, an exposure operation when the VD signal is at the Lo level, and captures a subject image at a timing synchronized with the VD signal. Therefore, the imaging apparatus performs the AF operation while detecting the contrast of the subject image exposed at the VD timing. Specifically, the lens microcomputer 8 instructs each component to perform an AF operation, and the motor 4 repeatedly finely drives the focus unit 3 to the near side and the infinite side at every VD timing, while the CCD sensor 13 detects the subject image. Detect contrast. At this time, for example, if the camera microcomputer 12 determines that the contrast is higher when driven to the infinity side, the camera microcomputer 12 instructs the lens microcomputer 8 to move the focus unit 3 to the infinity side, and again, the camera microcomputer 12 is again infinite with the closest side. The difference in contrast when driving with the side is detected. The camera microcomputer 12 repeats this operation, and determines that the camera is in focus when the contrast difference between driving to the near side and the infinity side becomes zero.

  Here, in the driving permission period of the AF operation 1 shown in FIG. 2, the lens microcomputer 8 performs control to always drive the focus unit 3 in the reverse direction and detect the driving amount and speed by the movement amount detection unit 5. The drive amount and speed are appropriately changed based on the absolute position information of the focus unit 3 detected by the absolute position detection unit 6. This is because the optical sensitivity characteristic varies depending on the absolute position of the focus unit 3. On the other hand, during the driving stop period of the AF operation 1 shown in FIG. 2, the camera microcomputer 12 compares the contrast values, determines the driving direction of the focus unit 3 to focus on the subject, and determines the determined direction and driving amount. Is transmitted to the interchangeable lens 1 through the contact unit 9. As described above, the camera microcomputer 12 appropriately transmits to the lens microcomputer 8 commands for permitting and stopping the driving of the focus unit 3. Based on this command, the lens microcomputer 8 repeats the reversing operation of the focus unit 3 in synchronization with the VD signal. At this time, the lens microcomputer 8 constantly transmits the driving direction information of the focus unit 3 to the camera microcomputer 12. Then, the camera microcomputer 12 determines in which direction the focus unit 3 is to be driven next based on this drive direction information.

Next, communication processing of the communication control apparatus will be described. First, a communication circuit between the lens microcomputer 8 and the camera microcomputer 12 via the contact unit 9 will be described. FIG. 3 is a schematic diagram showing a communication circuit between the lens microcomputer 8 and the camera microcomputer 12. In general, in communication between the interchangeable lens 1 and the camera body 2, various data are exchanged by a serial communication function set in each of the microcomputers 8 and 12. As shown in FIG. 3, the lens microcomputer 8 includes an input terminal L _in , an output terminal L _out, and a synchronous clock input terminal L _clk . Input terminal L _in is a terminal for receiving the output data from the camera microcomputer 12. The output terminal L _out is a terminal that transmits output data to the camera microcomputer 12. The synchronization clock input terminal L _clk is a terminal for synchronization in each of the data communication of L _in and L _out . Similarly, the camera microcomputer 12 includes an input terminal C _in , an output terminal C _out, and a synchronous clock output terminal C _clk . The input terminal C _in is a terminal that receives output data from the lens microcomputer 8. The output terminal C _out is a terminal that transmits output data to the lens microcomputer 8. The synchronous clock output terminal C _clk is a terminal for synchronizing in each data communication of C _in and C _out .

Next, an electrical signal when communication is performed via the communication circuit will be described. FIG. 4 is an electrical signal diagram for the output signal from the synchronous clock output terminal C _clk . The camera microcomputer 12, when performing communication with the lens microcomputer 8, when the output signal from the synchronous clock output terminal C _clk is changed over to Lo from Hi, the output signal from the output terminal C _out with respect to the lens microcomputer 8 Switch Hi / Lo. At this time, the lens microcomputer 8, the input terminal _{L in,} switch the Hi / Lo of the input signal from the camera microcomputer 12. Here, when the output signal from the synchronous clock output terminal C _{clk switches} from Lo to Hi, the camera microcomputer 12 takes in the input signal from the lens microcomputer 8 from the input terminal C _in to the internal register. Similarly, the lens microcomputer 8 also takes in the internal register input signal from the camera microcomputer 12 through the input terminal L _in. The lens microcomputer 8 and the camera microcomputer 12 are used for various processes of the imaging apparatus by repeating such mutual communication eight times in total and storing them as 1-byte data. For example, consider a case where communication is MSB first (Most Significant Byte First). At this time, as shown in FIG. 4, each transmitted data that 10011001B (99hex) is to 00111010B (3Ahex), whereas, the input terminal _{C in} the output terminal _{L out} from the output terminal _{C out} to the input terminal _{L in} . 3 and 4, the communication method of this embodiment has been described as clock synchronous serial communication, but other communication methods such as UART and USB may be employed.

  Next, a camera command transmitted from the camera microcomputer 12 to the lens microcomputer 8 will be described. FIG. 5 is a list showing camera commands including specific communication contents. Since normal camera command communication is performed asynchronously with respect to the VD signal described above, such a camera command is referred to as “camera command for asynchronous communication”. In this case, the lens microcomputer 8 analyzes the camera command received from the camera microcomputer 12 and controls various processes as instructions from the camera microcomputer 12.

  In FIG. 5, the camera command 10 hex is a command for transmitting characteristic information related to the mechanism of the interchangeable lens 1 from the interchangeable lens 1 to the camera body 2. In this case, the amount of data transmitted by the interchangeable lens 1 is defined as 8 bytes in advance. That is, after the lens microcomputer 8 transmits 8 bytes of data, the 9th byte is the next communication (data communication). The camera command 11 hex is a command for transmitting information related to the optics of the interchangeable lens 1 from the interchangeable lens 1 to the camera body 2. In this case, the amount of data transmitted by the interchangeable lens 1 is defined as 15 bytes in advance. The camera command 12 hex is a command for transmitting information related to the state of the interchangeable lens 1 from the interchangeable lens 1 to the camera body 2. In this case, the amount of data transmitted by the interchangeable lens 1 is defined in advance as 4 bytes. The information regarding the state of the interchangeable lens 1 includes drive direction information of the focus unit 3. The camera command 13 hex is two commands: a drive command for the focus unit 3 and a reception request command for causing the interchangeable lens 1 to receive the drive amount at this time. In this case, the data amount (drive amount) transmitted by the camera microcomputer 12 is defined as 3 bytes in advance. For example, when the driving amount is a negative numerical value, it is preliminarily defined as a near side driving, and when it is a positive numerical value, it is defined as an infinite driving. The camera command 14 hex is a command for receiving drive time information to the focus unit 3. In this case, the amount of data transmitted by the camera microcomputer 12 is defined as 2 bytes in advance. Here, the “driving time information” is specifically a driving time limit value when the focus unit 3 is driven by the camera command 13 hex. The lens microcomputer 8 determines the moving speed of the focus unit 3 based on the drive amount of the focus unit 3 and the drive time limit value. That is, the moving speed of the focus unit 3 is faster as the driving amount is larger and the driving time limit value is shorter. The camera command 14 hex is transmitted before the camera command 13 hex is transmitted from the camera microcomputer 12, and the lens microcomputer 8 instructs the focus unit 3 to start driving based on the driving time information of the camera command 14 hex received in advance. To do. Furthermore, the camera command 15 hex is a command related to the permission and prohibition of the reverse driving of the focus unit 3 described above. In this case, the amount of data transmitted by the camera microcomputer 12 is defined as 1 byte in advance. After receiving the camera command 15 hex, the lens microcomputer 8 instructs the focus unit 3 to start reversal driving based on the drive amount of the focus unit 3 previously received by the camera command 13 hex. At this time, if the value of the driving amount is zero, the inversion driving is prohibited. If the camera command 13 hex is received while the reverse drive is permitted by the camera command 15 hex, the camera command 13 hex is given priority. That is, when the lens microcomputer 8 finishes driving the focus unit 3 with the camera command 13 hex, it instructs the camera command 15 hex to be reversed.

  Here, the lens microcomputer 8 requires a VD signal in order to instruct the focus unit 3 to perform inversion driving. In particular, in this embodiment, a new camera command synchronized with the VD signal is added. FIG. 6 is a list showing camera commands to be synchronized with the VD signal. Since this camera command communication is synchronized with the VD signal described above, such a camera command is referred to as a “synchronous communication camera command (synchronous communication command)”. In FIG. 6, the camera command 20 hex is a command transmitted from the camera microcomputer 12 to the lens microcomputer 8 at the start of the exposure operation by the camera body 2. The camera command 20 hex is timing information (vertical synchronization command 1) with the data amount set to 0 bytes. The lens microcomputer 8 uses an internal timer dedicated to VD synchronization timing and operates to preset the next VD synchronization timing after receiving the camera command 20 hex. That is, the lens microcomputer 8 controls the reversing operation of the focus unit 3 based on the timer information. Similarly to the camera command 20 hex, the camera commands 21 hex to 2 Fhex are also commands that are transmitted from the camera microcomputer 12 to the lens microcomputer 8 when the exposure operation by the camera body 2 is started. The camera commands 21 hex to 2 F hex are also timing information (vertical synchronization command 2) with a data amount of 0 bytes. However, in the case of the camera commands 21 to 2Fhex, the 4-bit information located in the lower order thereof indicates the communication amount delayed from the actual VD synchronization signal.

Next, the operation of the camera command for synchronous communication according to this embodiment will be described. FIG. 7 is a conceptual diagram showing an output signal from the synchronous clock output terminal C _clk of the camera microcomputer 12. During communication between the lens microcomputer 8 and the camera microcomputer 12, the output signal from the synchronous clock output terminal C _clk changes as shown in FIG. Here, since the camera command for asynchronous communication shown in FIG. 5 is not synchronized with the VD signal, the camera microcomputer 12 communicates with the lens microcomputer 8 as necessary in various operations of the camera body 2. Furthermore, in this embodiment, when the camera microcomputer 12 transmits the VD signal, the camera command for synchronous communication shown in FIG. 6 is newly added to the output signal and transmitted to the lens microcomputer 8.

In FIG. 7, an output signal SIG ₁ is a signal diagram showing that 2 byte data of the camera command 14 hex, 8 byte data of the camera command 10 hex, and 4 byte data of the camera command 12 hex are transmitted in order. The output signal SIG ₂ is a signal diagram in which only the communication waveform of the camera command 14 hex of the output signal SIG ₁ is enlarged, and after transmitting the camera command 14 hex, which is a camera command for asynchronous communication, a 2-byte data 1 and data 2 Indicates that data is being transmitted. The output signal SIG ₃ is a signal diagram in which only the communication waveform of the camera command 10 hex of the output signal SIG ₁ is enlarged. After transmitting the camera command 10 hex which is a camera command for asynchronous communication, 8-byte data consisting of data 1 to 8 is transmitted. Indicates that is being sent.

Here, in the case of conventional communication, the camera microcomputer 12 cannot transmit a camera command for synchronous communication when a VD signal is transmitted during asynchronous communication. For example, when the camera microcomputer 12 first transmits the camera command 10 hex in the output signal SIG ₃ , the lens microcomputer 8 always transmits the specific information of the interchangeable lens 1 as described above. Here, as shown in FIG. 7, it is assumed that a VD signal is transmitted with data 2 (second byte of data communication) (VD timing A). At this time, since the camera microcomputer 12 is receiving data related to the asynchronous communication camera command 10 hex, the camera microcomputer 12 cannot transmit the synchronous communication camera command to the lens microcomputer 8. Therefore, the lens microcomputer 8 can receive the VD signal transmitted at the VD timing A at the position of the VD timing B at which the asynchronous communication is completed, and the VD timing is shifted. This deviation in VD timing results in a start deviation of the AF operation in the interchangeable lens 1 as in the AF operation 2 shown in FIG. On the other hand, when the VD signal is transmitted when the asynchronous communication is not performed (VD timing C), the VD timing is not shifted.

Therefore, in this embodiment, different synchronous communication camera commands are used at VD timing B and VD timing C as shown in FIG. For example, the camera command 20 hex is used at the timing when asynchronous communication is not performed as in VD timing C, while the camera commands 21 hex to 2 Fhex are used at timing during asynchronous communication as VD timing B. To do. At this time, the information of the lower 4 bits of the camera commands 21 hex to 2 Fhex specifically indicates the byte number of the previous asynchronous communication in which the VD signal is transmitted. For example, in the output signal SIG ₃ , the first byte is the camera command 10 hex, the next second byte is the data 1 (first byte of data communication), and the third byte of data 2 (data communication 2 VD timing A occurs at the time of communication (byte). Therefore, the lens microcomputer 8 transmits the camera command 23 hex in the sense of the camera command 20 hex + the third byte at the VD timing B when the asynchronous communication ends. At this time, the lens microcomputer 8 always stores all VD signal timings with reference to a timer dedicated to VD synchronization timing provided therein, and VD timing at the time of reception based on lower-order 4-bit information of the camera command for synchronous communication. To derive the delayed VD timing. That is, this delay VD timing is temporal delay information. Then, the lens microcomputer 8 corrects the VD timing information based on the derived delay VD timing, thereby controlling the AF operation with accurate VD timing information.

  Here, a method for generating a camera command for synchronous communication in the camera microcomputer 12 will be described. First, in the camera microcomputer 12, a timer interrupt for generating a VD synchronization signal is generated. Here, the camera microcomputer 12 determines whether it is currently communicating with the lens microcomputer 8, and when not communicating, transmits the camera command 20 hex to the lens microcomputer 8. On the other hand, when communicating with the lens microcomputer 8, the camera microcomputer 12 determines how many bytes of communication the data amount including the asynchronous communication camera command is.

  Next, a method for generating a VD synchronization signal in the lens microcomputer 8 will be described. The lens microcomputer 8 controls the AF operation when the timer interruption occurs. At this time, whenever the lens microcomputer 8 receives a camera command for synchronous communication from the camera microcomputer 12, the lens microcomputer 8 stores the timer value in the internal memory and determines the generation position of the VD timing. In addition, every time a camera command for synchronous communication is received from the camera microcomputer 12, the lens microcomputer 8 sets an interrupt time for the next new VD timing, and always updates the latest VD timing information. For example, when receiving the synchronous communication camera command 20 hex, the lens microcomputer 8 writes a value obtained by adding the next VD timing to the current timer value to an internal register that performs interrupt processing. On the other hand, when receiving the synchronous communication camera command 23 hex, the lens microcomputer 8 recognizes that the VD timing A has occurred at the third byte of the previous asynchronous communication. Then, the lens microcomputer 8 reads the 3rd byte VD timing information from the internal memory storing the VD timing, and writes the value obtained by adding the next VD timing to the information to the internal register.

  Next, interrupt processing by the lens microcomputer 8 will be described. FIG. 8 is a flowchart showing the flow of interrupt processing by the lens microcomputer 8 when a camera command for synchronous communication is received from the camera microcomputer 12. First, when the interrupt processing is started (step S100), the lens microcomputer 8 stores a timer value (counter value) for determining the VD timing in the internal memory (step S101). Here, the lens microcomputer 8 includes a maximum of 16 internal memories. For example, when the communication content transmitted from the camera microcomputer 12 is a camera command for asynchronous communication, the lens microcomputer 8 stores a timer value in “memory 1”. On the other hand, in the case of data or a camera command for synchronous communication, the lens microcomputer 8 stores the contents in order after “Memory 2”. That is, step S101 includes processing for constantly grasping how far the lens microcomputer 8 is using the internal memory.

  Next, the lens microcomputer 8 determines whether the communication content transmitted from the camera microcomputer 12 is an asynchronous communication including the camera command and data for asynchronous communication based on the analysis result of the communication content in step S101. (Step S102). At this time, if the lens microcomputer 8 determines that the communication content transmitted from the camera microcomputer 12 is asynchronous communication (Y), the lens microcomputer 8 analyzes the determination result of the camera command for asynchronous communication, and the normal state as shown in FIG. The various communication processes are performed (step S103). On the other hand, if the lens microcomputer 8 determines that the communication content transmitted from the camera microcomputer 12 is synchronous communication including the camera command for synchronous communication (N), the camera command for synchronous communication is the camera command 20 hex or otherwise. Is determined (step S104).

If the lens microcomputer 8 determines in step S104 that the camera command for synchronous communication is the camera command 20hex (Y), the lens microcomputer 8 recognizes that the current communication timing is the VD timing. Then, the lens microcomputer 8 acquires the current timer value in order to determine the next VD timing, and adds the value of the VD timing stored therein in advance (step S105). On the other hand, if the lens microcomputer 8 determines in step S104 that the camera command for synchronous communication is not the camera command 20 hex (N), the lens microcomputer 8 recognizes that the VD timing has occurred before the current communication timing. At this time, in order to determine the next VD timing, the lens microcomputer 8 determines the numerical value of the lower 4 bits information of the camera command for synchronous communication. Considering the example in FIG. 7, this value is “3” in this case because the output signal SIG ₃ indicates the third byte communication in the previous asynchronous communication. The lens microcomputer 8 determines from this numerical value “3” that the VD timing A is generated in “memory 3” of the memory information grasped in step S101. Then, the lens microcomputer 8 reads the timer value of “memory 3” and adds the value of the VD timing stored in advance therein (step S106). Then, the lens microcomputer 8 writes the value added in step S105 or step S106 to the internal register that determines the next interrupt (step S107), and ends the interrupt process (step S108). When the VD timing set by this interrupt processing elapses, an interrupt of the VD signal occurs. Therefore, the lens microcomputer 8 may perform AF control based on the correction result by this interruption process.

  As described above, according to the communication control apparatus of the present invention, by applying the camera command for synchronous communication to the VD signal that is the reference of the AF operation, the deviation of the generation position (generation time) of the VD timing information is reduced. Correct as appropriate. Therefore, for example, even when the user performs an emergency operation that suddenly stops the AF operation, the focus unit can react immediately, so that the operability of the imaging device itself provided with the communication control device of the present invention is improved. Will improve. In addition, since it is not necessary to install a dedicated communication terminal for transmitting the timing at which the electronic image sensor starts exposure to the interchangeable lens, an inexpensive interchangeable lens and camera body can be provided.

(Second Embodiment)
Next, a communication control apparatus according to the second embodiment of the present invention will be described. Here, the camera command 12 hex to 2F hex for synchronous communication in the first embodiment cannot be transmitted because the camera microcomputer 12 has tried to transmit to the lens microcomputer 8 because VD timing has conventionally occurred. Applicable when The low-order 4-bit information of the synchronous communication camera commands 21 hex to 2 Fhex is time delay information from the time when the VD timing is generated to the time of transmission to the actual lens microcomputer 8. For example, the difference between 21 hex and 22 hex is 1, which is 500 (μsec) in terms of time. Therefore, in this embodiment, the camera microcomputer 12 calculates the delay time (delay information) from the VD timing A before transmitting the camera command for synchronous communication at the VD timing B in FIG. It is added to the camera command 20 hex for synchronous communication and transmitted. For example, at VD timing C in FIG. 7, the camera command for synchronous communication is simply 20 hex, that is, the delay time in this case is zero.

  As a calculation method of the delay time, the camera microcomputer 12 may divide the delay time from the VD timing B to the VD timing A by 500 (μsec) and add the calculation result to the synchronous communication camera command 20 hex. At this time, since the maximum delay time is 15 (pieces) × 500 (μsec) = 7.5 (msec), all asynchronous communications are completed in a shorter time. On the other hand, the lens microcomputer 8 multiplies the lower 4 bits of the camera command for synchronous communication by 500 (μsec), and subtracts the multiplication result from the value obtained by adding the current timer value and the preset VD timing value. Calculate accurate VD timing. Thus, in this embodiment, in addition to the effect of the first embodiment, the lens microcomputer 8 does not need to store the VD timing information of the previous asynchronous communication, that is, the timer is not required. Is easy.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

  For example, in the above-described embodiment, the VD timing is described as synchronous communication. However, the present invention can be applied to communication of a system that requires communication every predetermined time or communication from another unit other than the CCD sensor 13. Is possible.

1 Interchangeable lens 2 Camera body 8 Lens microcomputer 12 Camera microcomputer

Claims (5)

A camera system having an interchangeable lens and a camera body,
The interchangeable lens has lens control means for controlling the operation of the interchangeable lens and communicating with the camera body ,
The camera body has camera control means for controlling the operation of the camera body and communicating with the interchangeable lens ,
The lens control means and the camera control means communicate by an asynchronous communication method,
The lens control means performs synchronization control based on a vertical synchronization signal transmitted from the camera control means,
The camera control means, when communication is not performed between the lens control means and the camera control means, provides timing information for performing the synchronization control at a synchronization timing determined based on the vertical synchronization signal. Transmitted to the lens control means,
When communication is performed between the lens control unit and the camera control unit at the synchronization timing, the timing information including delay information with respect to the synchronization timing is transmitted to the lens control after the communication ends. A camera system for transmitting to a means . The camera system according to claim 1 , wherein the delay information is information related to a time from the synchronization timing until communication between the lens control unit and the camera control unit ends. The lens control means, a camera system according to claim 1 or 2, based on the delay information, wherein the setting the synchronization control line cormorants timing. A removable interchangeable lens to a camera body having a camera control unit,
A lens control unit that controls the operation of the interchangeable lens and communicates with the camera body by an asynchronous communication method ;
The camera control means controls the operation of the camera body, and can communicate with the interchangeable lens by an asynchronous communication method.
The lens control means performs synchronization control based on a vertical synchronization signal transmitted from the camera control means,
Timing information for performing the synchronization control is received from the camera control means at a synchronization timing determined based on the vertical synchronization signal;
When communication is performed between the lens control unit and the camera control unit at the synchronization timing, the timing information including delay information with respect to the synchronization timing is controlled by the camera after the communication ends. Received from the means,
An interchangeable lens, wherein the synchronization control is performed based on the timing information. A interchangeable lens camera main body detachable with lenses control means,
Camera control means for controlling the operation of the camera body and communicating with the interchangeable lens by an asynchronous communication method ;
The lens control means controls the operation of the interchangeable lens and can communicate with the camera body by an asynchronous communication method.
The camera control means transmits a vertical synchronization signal for causing the lens control means to execute synchronization control, to the lens control means,
Timing information for causing the lens control means to execute the synchronization control is transmitted to the lens control means at a synchronization timing determined based on the vertical synchronization signal,
When communication is performed between the lens control unit and the camera control unit at the synchronization timing, the timing information including delay information with respect to the synchronization timing is transmitted to the lens control after the communication ends. A camera body characterized by transmitting to the means.

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