JP2020112819A - Accessory device, imaging device, and communication control program - Google Patents

Abstract

To provide an accessory device and an imaging device that can transmit and receive data at high speed without causing communication to fail without adding a new channel.SOLUTION: There is provided a channel between an imaging device 200 and an accessory device 100, including a notification channel used for notice from the imaging device 200 to the accessory device 100, and an accessory data communication channel used for transmission of data from the accessory device to the imaging device. An accessory control unit 111 transmits data to the imaging device 200 via the accessory data communication channel in response to reception of a transmission request signal, and transmits a communication wait request signal to the imaging device 200 so as to prevent a transmission request signal from being transmitted from the imaging device 200 to the accessory device 100 via the accessory data communication channel.SELECTED DRAWING: Figure 4

Description

The present invention relates to an image pickup apparatus and an accessory apparatus such as an interchangeable lens that can communicate with each other.

As a lens interchangeable camera system, there is known a system in which an imaging device as a camera main body performs image capturing processing and lens control, and a lens device as an interchangeable lens drives a lens according to a control command from the camera main body. In such a camera system, the transmission of control commands from the camera body to the interchangeable lens and the transmission of lens information from the interchangeable lens to the camera body are performed via a communication channel for exchanging information with each other.

Further, among the interchangeable-lens type camera systems, particularly in digital camera systems, smooth lens control in accordance with the imaging cycle is required at the time of moving image shooting and live view shooting. For this purpose, it is necessary to synchronize the image capturing timing of the camera body with the control timing of the interchangeable lens, and the camera body acquires the lens information necessary for lens control and transmits the control command to the interchangeable lens in the image capturing cycle. Must be completed within.

On the other hand, the sophistication of imaging technology has increased the amount of lens information data that the camera body acquires from the interchangeable lens, and has increased the frame rate. As a result, it becomes necessary to communicate a large amount of data in a shorter time than in the past.

Patent Document 1 discloses a clock-synchronized communication system including a clock channel, a data transmission channel from a camera body to an interchangeable lens, and a data transmission channel from an interchangeable lens to a camera body. There is. In this communication system, the camera body first generates a clock signal as a communication master, and outputs a one-frame clock signal to the interchangeable lens via the clock channel. After that, the inputs and outputs of the clock channels are switched, and the interchangeable lens that has become the communication master instead of the camera body outputs a communication standby request to the same channel. As a result, the interchangeable lens can notify the camera body that it is in a processing waiting state after communication.

JP, 9-304804, A

In the communication system disclosed in Patent Document 1, it is necessary to switch the communication master between the camera body that outputs a clock signal and the interchangeable lens that outputs a communication standby request in the same channel by time management. Therefore, in order to prevent communication collision, it is necessary to provide a time for switching communication masters, that is, a communication invalid time during which communication cannot be performed, which may result in delay of communication and control.

In order to solve such a problem, if the output of the communication standby request signal from the interchangeable lens to the clock channel is stopped, the communication standby request from the interchangeable lens to the camera body cannot be made at all. If a large amount of data is communicated without outputting a communication standby request signal, communication may break if the receiving lens overflows in the interchangeable lens that is the communication slave or the data to be transmitted to the camera body cannot be generated in time. There is. Further, if a new channel is provided to output the communication standby request signal, power consumption increases, which hinders downsizing of the camera body and the interchangeable lens.

An object of the present invention is to provide an accessory device and an imaging device that can perform high-speed data transmission/reception without causing a communication failure without adding a new channel.

An accessory device that is attachable to and detachable from an imaging device, and a notification channel used for notification from the imaging device to the accessory device, and data transmission from the accessory device to the imaging device. An accessory data communication channel provided with a channel including an accessory data communication channel, and an accessory control unit that controls the accessory communication unit, wherein the accessory control unit transmits data from the accessory device to the imaging device. In response to receiving a transmission request signal for requesting via the notification channel, transmitting data to the imaging device via the accessory data communication channel, and the accessory control unit controls the accessory data communication. A communication standby request signal for preventing the transmission request signal from being transmitted from the imaging device to the accessory device via a channel is transmitted to the imaging device.

The image pickup apparatus of the present invention is an image pickup apparatus to which an accessory device is detachably attached, and is a notification used for transmitting a transmission request signal from the image pickup apparatus to the accessory device between the accessory device and the accessory device. An imaging device communication unit that includes a channel and a channel including an accessory data communication channel used for data transmission from the accessory device to the imaging device, and an imaging device control unit that controls the imaging device communication unit, The imaging device control unit, while the communication standby request signal for preventing the transmission request signal from being transmitted, is notified from the accessory device via the accessory data communication channel, the transmission request signal It is characterized in that it is not transmitted to the accessory device.

According to the present invention, it is possible to obtain an accessory device and an imaging device that can perform high-speed data transmission/reception without causing a communication failure without adding a new channel.

It is a block diagram which shows the structure of the camera system containing the imaging device and accessory device of this invention. It is a schematic diagram showing a communication circuit between an imaging device and an accessory device. It is a schematic diagram showing a communication waveform in communication mode M1. It is a schematic diagram showing a communication waveform in communication mode M2. It is a schematic diagram showing a communication waveform in communication mode M3. It is a flowchart explaining the flow which determines a communication format in an accessory device and an imaging device. It is a flow chart explaining the data communication flow in communication mode M2.

Hereinafter, a communication control method in an interchangeable lens as an accessory device and a camera body as an imaging device of the present invention will be described in detail with reference to the accompanying drawings. First, the definition of terms in this embodiment will be described.

“Communication format” indicates the overall agreement between the camera body and the interchangeable lens. “Communication system” means a clock synchronous system and an asynchronous system, and the clock synchronous system is a communication system A and the asynchronous system is a communication system B. “Data format” indicates whether or not a communication standby request signal (BUSY signal) can be added. The data format that allows the BUSY signal to be added is “format F1” and the data format that prohibits the BUSY signal to be added is “format F2”. And

“Communication mode” means a combination of a communication method and a data format, and in this embodiment, the following three communication modes will be described. "Communication mode M1" is a communication mode A and format F1 communication mode, and "communication mode M2" is a communication mode B and format F1 communication mode. The "communication mode M3" is the communication mode B and the communication mode of the format F2.

The present invention relates to communication control between the camera body and the interchangeable lens in the communication mode M2. In the following embodiment, an imaging system having a camera body and an interchangeable lens that can communicate by switching a plurality of communication modes including a communication mode M2 will be shown. By appropriately switching the communication modes in this way to perform communication, an appropriate communication mode can be selected according to the combination of the camera body and the interchangeable lens and the shooting mode.

For example, when the camera body and the interchangeable lens are compatible with the communication mode M3 and a large amount of data is transmitted and received, after switching the respective communication modes to the communication mode M3, the high speed in which the addition of the BUSY signal is prohibited. Data communication is performed. When it takes some time for data processing in the interchangeable lens, the communication mode of the camera body and the interchangeable lens is switched to the communication mode M2, and then data communication in which the BUSY signal is permitted to be added is performed. As a result, it is possible to perform data communication between the camera body and the interchangeable lens without causing communication failure.

FIG. 1 is a configuration of an image pickup system (hereinafter, referred to as a camera system) including a camera body 200 as an image pickup apparatus according to a first embodiment of the present invention and an interchangeable lens 100 as an accessory device detachably attached thereto. Is shown.

The camera body 200 and the interchangeable lens 100 transmit control commands and internal information via their respective communication units. Also, each communication unit supports multiple communication formats, and by switching to the same communication format in synchronization with each other according to the type of communication data and the purpose of communication, the optimum communication format for various situations can be selected. It is possible to do.

First, the specific configurations of the interchangeable lens 100 and the camera body 200 will be described. The interchangeable lens 100 and the camera body 200 are mechanically and electrically connected via a mount 300 that is a coupling mechanism. The interchangeable lens 100 receives power from the camera body 200 via a power supply terminal (not shown) provided on the mount 300, and controls various actuators and a lens microcomputer (hereinafter, referred to as a lens microcomputer) 111 described later. Further, the interchangeable lens 100 and the camera body 200 communicate with each other via a communication terminal (shown in FIG. 2) provided on the mount 300.

The interchangeable lens 100 has an image pickup optical system. The imaging optical system includes, in order from the object OBJ side, a field lens 101, a variable power lens 102 that performs variable power, a diaphragm unit 114 that adjusts the amount of light, an image blur correction lens 103, and a focus lens 104 that performs focus adjustment. including.

The variable power lens 102 and the focus lens 104 are held by lens holding frames 105 and 106, respectively. The lens holding frames 105 and 106 are guided by a guide shaft (not shown) so as to be movable in the optical axis direction indicated by a broken line in the figure, and are driven in the optical axis direction by stepping motors 107 and 108, respectively. The stepping motors 107 and 108 respectively move the variable power lens 102 and the focus lens 104 in synchronization with the drive pulse.

The image blur correction lens 103 moves in a direction orthogonal to the optical axis of the imaging optical system to reduce image blur caused by camera shake or the like.

The lens microcomputer 111 is an accessory control unit that controls the operation of each unit in the interchangeable lens 100. The lens microcomputer 111 receives the control command transmitted from the camera body 200 via the lens communication unit 112 as an accessory communication unit, and receives a lens data transmission request. In addition, the lens microcomputer 111 performs lens control corresponding to the control command, and transmits lens data corresponding to the transmission request to the camera body 200 via the lens communication unit 112.

In addition, the lens microcomputer 111 outputs a drive signal to the zoom drive circuit 119 and the focus drive circuit 120 in response to a command relating to zooming and focusing among the control commands to drive the stepping motors 107 and 108. As a result, zoom processing for controlling the zooming operation by the zooming lens 102 and autofocus processing for controlling the focus adjusting operation by the focus lens 104 are performed.

The diaphragm unit 114 includes diaphragm blades 114a and 114b. The states of the diaphragm blades 114a and 114b are detected by the Hall element 115 and input to the lens microcomputer 111 via the amplifier circuit 122 and the A/D conversion circuit 123. The lens microcomputer 111 outputs a drive signal to the diaphragm drive circuit 121 based on an input signal from the A/D conversion circuit 123 to drive the diaphragm actuator 113. This controls the light amount adjustment operation by the diaphragm unit 114.

Further, the lens microcomputer 111 drives the anti-vibration actuator 126 via the anti-vibration drive circuit 125 according to the shake detected by a shake sensor (not shown) such as a vibration gyro provided in the interchangeable lens 100. As a result, the image stabilization process for controlling the shift operation of the image blur correction lens 103 is performed.

The camera body 200 includes an image sensor 201 such as a CCD sensor or a CMOS sensor, an A/D conversion circuit 202, a signal processing circuit 203, a recording unit 204, a camera microcomputer (hereinafter referred to as a camera microcomputer) 205, and a display. And part 206.

The image pickup element 201 photoelectrically converts the subject image formed by the image pickup optical system in the interchangeable lens 100 and outputs an electric signal (analog signal). The A/D conversion circuit 202 converts an analog signal from the image sensor 201 into a digital signal. The signal processing circuit 203 performs various kinds of image processing on the digital signal from the A/D conversion circuit 202 to generate a video signal.

The signal processing circuit 203 also generates, from the video signal, the contrast state of the subject image, that is, the focus information indicating the focus state of the imaging optical system and the brightness information indicating the exposure state. The signal processing circuit 203 outputs the video signal to the display unit 206, and the display unit 206 displays the video signal as a live view image used for confirmation of the composition, focus state, and the like.

The camera microcomputer 205 as a camera control unit controls the camera body 200 in response to inputs from camera operation members such as an imaging instruction switch and various setting switches (not shown). In addition, the camera microcomputer 205 transmits a control command relating to the variable magnification operation of the variable magnification lens 102 to the lens microcomputer 111 via the camera data transmission/reception unit 208 according to the operation of a zoom switch (not shown). Further, the camera microcomputer 205 transmits, to the lens microcomputer 111, a control command relating to a light amount adjusting operation of the aperture unit 114 according to the brightness information and a focus adjusting operation of the focus lens 104 according to the focus information via the camera data transmitting/receiving unit 208b. To do.

Next, a communication circuit configured between the camera body 200 and the interchangeable lens 100 and communication control performed between them will be described with reference to FIG. The camera microcomputer 205 has a function of managing a communication format with the lens microcomputer 111 and a function of notifying the lens microcomputer 111 of a transmission request or the like. Further, the lens microcomputer 111 has a function of generating lens data and a function of transmitting the lens data.

The camera microcomputer 205 and the lens microcomputer 111 communicate with each other via communication terminals provided on the mount 300 and communication interface circuits 208a and 112a provided respectively. Here, the communication interface circuit 208a and the camera data transmission/reception unit 208b are collectively referred to as a camera communication unit 208, and the communication interface circuit 112a and the lens data transmission/reception unit 112b are collectively referred to as a lens communication unit 112.

In the present embodiment, the camera microcomputer 205 and the lens microcomputer 111 perform serial communication by the three-wire communication method A and the communication method B using three channels.

One of the three channels is a notification channel that is a clock channel in communication method A and a transmission request channel in communication method B. One of the other two channels is a first data communication channel (accessory data communication channel) used for lens data transmission from the lens microcomputer 111 to the camera microcomputer 205. The other channel is a second data communication channel (imaging device data communication channel) used for camera data transmission from the camera microcomputer 205 to the lens microcomputer 111.

Lens data transmitted as a signal from the lens microcomputer 111 to the camera microcomputer 205 on the first data communication channel is referred to as a lens data signal DLC. Further, camera data transmitted as a signal from the camera microcomputer 205 to the lens microcomputer 111 on the second data communication channel is referred to as a camera data signal DCL.

First, communication in the communication method A will be described. In the communication method A, the clock signal LCLK is output from the camera microcomputer 205 as the communication master to the lens microcomputer 111 as the communication slave via the clock channel. The camera data signal DCL includes a control command from the camera microcomputer 205 to the lens microcomputer 111, a transmission request command, and the like. On the other hand, the lens data signal DLC includes various data transmitted from the lens microcomputer 111 to the camera microcomputer 205 in synchronization with the clock signal LCLK. The camera microcomputer 205 and the lens microcomputer 111 can communicate with each other by a full-duplex communication method (full-duplex method) in which transmission and reception are mutually and simultaneously performed in synchronization with a common clock signal LCLK.

FIGS. 3A to 3C show waveforms of signals exchanged between the camera microcomputer 205 and the lens microcomputer 111. The protocol for this exchange procedure is called a communication protocol.

FIG. 3A shows a signal waveform of one frame which is the minimum communication unit. First, the camera microcomputer 205 outputs a clock signal LCLK having a set of eight-cycle clock pulses, and transmits a camera data signal DCL to the lens microcomputer 111 in synchronization with the clock signal LCLK. At the same time, the camera microcomputer 205 receives the lens data signal DLC output from the lens microcomputer 111 in synchronization with the clock signal LCLK.

In this way, 1 byte (8 bits) of data is transmitted and received between the lens microcomputer 111 and the camera microcomputer 205 in synchronization with a set of clock signals LCLK. This 1-byte data transmission/reception period is called a data frame. After transmitting/receiving this 1-byte data, the lens microcomputer 111 transmits a signal (hereinafter referred to as a BUSY signal) for notifying the communication standby request BUSY to the camera microcomputer 205, whereby the communication standby period is inserted. This communication waiting period is called a BUSY frame, and the camera microcomputer 205 is in a communication waiting state while receiving the BUSY frame. Then, one frame is a communication unit in which the data frame period and the BUSY frame period are paired. Depending on the communication status, the BUSY frame may not be added, but in this case, one frame is composed of only the data frame period.

FIG. 3B shows a signal waveform when the camera microcomputer 205 transmits a request command CMD1 to the lens microcomputer 111 and receives 2-byte lens data DT1 (DT1a, DT1b) corresponding thereto from the lens microcomputer 111. ing. FIG. 3B shows an example in which data communication is executed according to “communication CMD1”.

Between the camera microcomputer 205 and the lens microcomputer 111, the type and the number of bytes of the lens data DT corresponding to each of the plurality of types of commands CMD are determined in advance. When the camera microcomputer 205, which is a communication master, sends a specific command CMD to the lens microcomputer 111, the lens microcomputer 111 sends the required number of clocks to the camera microcomputer 205 based on the information on the number of lens data bytes corresponding to the command CMD. To do. The processing of the lens microcomputer 111 for the command CMD1 includes superimposing the BUSY signal on the clock signal LCLK of each frame, and the above-mentioned BUSY frame is inserted between the data frames.

In the communication CMD1, the camera microcomputer 205 transmits a clock signal LCLK to the lens microcomputer 111, and further transmits a request command CMD1 requesting transmission of the lens data DT1 to the lens microcomputer 111 as a camera data signal DCL. The lens data signal DLC in this frame is treated as invalid data.

Subsequently, the camera microcomputer 205 outputs the clock signal LCLK for eight cycles on the clock channel, and then switches the clock channel on the camera microcomputer side (camera body side) from the output setting to the input setting. When the switching of the clock channel on the camera microcomputer side is completed, the lens microcomputer 111 switches the clock channel on the lens microcomputer 111 side (interchangeable lens side) from the input setting to the output setting. Then, the lens microcomputer 111 sets the voltage level of the clock channel to Low in order to notify the camera microcomputer 205 of the communication standby request BUSY. As a result, the BUSY signal is superimposed on the clock channel. The camera microcomputer 205 maintains the input setting of the clock channel during the period when the communication standby request BUSY is notified, and stops the communication to the lens microcomputer 111.

The lens microcomputer 111 generates the lens data DT1 corresponding to the transmission request command CMD1 during the communication standby request BUSY notification period. When the preparation for transmitting the lens data DT1 as the lens data signal DLC of the next frame is completed, the signal level of the clock channel on the lens microcomputer side is switched to High and the communication standby request BUSY is released.

Upon recognizing the release of the communication standby request BUSY, the camera microcomputer 205 transmits the one-frame clock signal LCLK to the lens microcomputer 111 to receive the lens data DT1a from the lens microcomputer 111. In the next frame, the camera microcomputer 205 outputs the clock signal LCLK again for 8 cycles, and the camera microcomputer 205 and the lens microcomputer 111 repeat the same operation as described above, so that the camera microcomputer 205 receives the lens data DT1b from the lens microcomputer 111. ..

FIG. 3C shows a signal waveform when the camera microcomputer 205 transmits the request command CMD2 to the lens microcomputer 111 and receives 3-byte lens data DT2 (DT2a to DT2c) corresponding thereto from the lens microcomputer 111. ing. FIG. 3C shows an example in which data communication is executed according to the communication CMD2. The processing of the lens microcomputer 111 for the request command CMD2 in the communication CMD2 includes superimposing the BUSY signal on the clock channel only in the first frame. That is, the lens microcomputer 111 does not superimpose the BUSY signal on the subsequent second to fourth frames.

Accordingly, the BUSY frame is not inserted between the second frame to the fourth frame, and the waiting period between the frames can be shortened. However, the lens microcomputer 111 cannot send a communication standby request to the camera microcomputer 205 while the BUSY frame is not inserted. Therefore, it is necessary to determine the number of data to be transmitted, the transmission interval, the priority order of communication processing in the lens microcomputer 111, and the like so as not to cause communication failure.

Next, communication in the communication method B will be described. Here, the communication mode M2 in which communication is performed in the format F1 using the communication method B will also be described. FIG. 4 shows a waveform of a communication signal exchanged between the camera microcomputer 205 and the lens microcomputer 111 in the communication mode M2. As described above, in the format F1, the BUSY frame is selectively added to the lens data signal DLC.

In the communication method B, the transmission request channel is used for notification of a lens data transmission request or the like from the camera microcomputer 205, which is a communication master, to the lens microcomputer 111, which is a communication slave. The notification on the transmission request channel is performed by switching the level (voltage level) of the signal on the transmission request channel between High (first level) and Low (second level). In the following description, the signal supplied to the transmission request channel in communication method B is referred to as the transmission request signal RTS.

The first data communication channel is used to transmit the lens data signal DLC including various data from the lens microcomputer 111 to the camera microcomputer 205, as in the communication method A. Similarly to the communication method A, the second data communication channel is also used for transmitting the camera data signal DCL including the control command and the transmission request command from the camera microcomputer 205 to the lens microcomputer 111.

In the communication method B, unlike the communication method A, the camera microcomputer 205 and the lens microcomputer 111 do not transmit and receive data in synchronization with a common clock signal, but set a communication speed in advance and perform communication based on this setting. Send and receive at the bit rate. The communication bit rate indicates the amount of data that can be transferred in one second, and the unit is represented by bps (bit per second).

In this embodiment, also in the communication method B, as in the communication method A, the camera microcomputer 205 and the lens microcomputer 111 communicate with each other by a full-duplex communication method (full-duplex method).

FIG. 4 shows a signal waveform of one frame which is the minimum communication unit. The breakdown of the data format of one frame is partially different between the camera data signal DCL and the lens data signal DLC.

First, the data format of the lens data signal DLC will be described. The lens data signal DLC for one frame is composed of a first half data frame and a BUSY frame that follows it. The signal level of the lens data signal DLC is maintained at High when data is not being transmitted.

The lens microcomputer 111 sets the voltage level of the lens data signal DLC to LOW for one bit period in order to notify the camera microcomputer 205 of the start of transmission of one frame of the lens data signal DLC. This 1-bit period is called a start bit ST, and the data frame starts from the start bit ST. Subsequently, the lens microcomputer 111 transmits 1-byte lens data in the 8-bit period from the second bit to the ninth bit following the start bit ST.

The bit arrangement of the data is MSB (Most Significant Bit) first format, starting from the highest data D7, followed by data D6 and data D5 in order, and ending with the lowest data D0. Then, the lens microcomputer 111 adds 1-bit parity information (PA) to the 10th bit and sets the voltage level of the lens data signal DLC to HIGH during the stop bit SP indicating the end of one frame. As a result, the data frame period started from the start bit ST ends. The parity information does not have to be 1 bit, and the parity information of a plurality of bits may be added. Further, the parity information is not essential, and the format may be such that the parity information is not added.

Subsequently, as indicated by "DLC (with BUSY)" in the figure, the lens microcomputer 111 adds a BUSY frame after the stop bit SP. Like the communication method A, the BUSY frame represents the period of the communication standby request BUSY notified from the lens microcomputer 111 to the camera microcomputer 205. The lens microcomputer 111 holds the signal level of the lens data signal DLC at Low until the communication standby request BUSY is released.

On the other hand, it may be unnecessary to notify the communication standby request BUSY from the lens microcomputer 111 to the camera microcomputer 205. For this case, as shown in “DLC (without BUSY)” in the figure, a data format that forms one frame without adding a BUSY frame (hereinafter, also referred to as BUSY notification) is also provided. That is, as the data format of the lens data signal DLC, it is possible to select whether the BUSY notification is added or not, depending on the processing status on the lens microcomputer side.

A method of identifying whether or not there is a BUSY notification performed by the camera microcomputer 205 will be described. The signal waveform shown in "DLC (without BUSY)" in FIG. 4 and the signal waveform shown in "DLC (with BUSY)" in FIG. 4 include bit positions B1 and B2. The camera microcomputer 205 selects one of these bit positions B1 and B2 as the BUSY identification position P for identifying the presence/absence of BUSY notification. As described above, the present embodiment adopts the data format for selecting the BUSY identification position P from the bit positions of B1 and B2. Accordingly, it is possible to deal with the problem that the processing time until the BUSY notification (DLC Low) is determined after the transmission of the data frame of the lens data signal DLC is different depending on the processing performance of the lens microcomputer 111.

Whether to set the BUSY identification position P to the bit position of B1 or the bit position of B2 is determined by communication between the camera microcomputer 205 and the lens microcomputer 111 before performing communication in the communication method B. The BUSY identification position P does not have to be fixed to one of the bit positions B1 and B2, and may be changed according to the processing capabilities of the camera microcomputer 205 and the lens microcomputer 111. The BUSY identification position P is not limited to B1 and B2, and can be set at a predetermined position after the stop bit SP.

Here, the reason why the BUSY frame added to the clock signal LCLK in the communication method A has a data format added to the lens data signal DLC in the communication method B will be described.

In the communication method A, it is necessary to exchange the clock signal LCLK output by the camera microcomputer 205, which is a communication master, and the BUSY signal output by the lens microcomputer 111, which is a communication slave, on the same clock channel. Therefore, the collision between the outputs of the camera microcomputer 205 and the lens microcomputer 111 is prevented by the time division method. That is, it is possible to prevent collision between outputs by appropriately assigning the output possible period of the camera microcomputer 205 and the lens microcomputer 111 in the clock channel.

However, in this time division method, it is necessary to surely prevent a collision between the outputs of the camera microcomputer 205 and the lens microcomputer 111. Therefore, from the time when the camera microcomputer 205 completes the output of the 8-pulse clock signal LCLK to the time when the lens microcomputer 111 permits the output of the BUSY signal, the output of both microcomputers 205 and 111 is prohibited. The output prohibition period of is inserted. This output prohibition period is a communication invalid period in which the camera microcomputer 205 and the lens microcomputer 111 cannot communicate with each other, which causes a reduction in effective communication speed.

In order to solve such a problem, in the communication method B, a data format for adding a BUSY frame from the lens microcomputer 111 to the lens data signal DLC in the first data communication channel which is a dedicated output channel of the lens microcomputer 111 is used. It is adopted.

Next, the data format of the camera data signal DCL will be described. The specifications of one data frame are the same as those of the lens data signal DLC. However, unlike the lens data signal DLC, the camera data signal DCL is prohibited from adding a BUSY frame.

Next, a procedure of communication in the communication method B between the camera microcomputer 205 and the lens microcomputer 111 will be described. First, when an event to start communication with the lens microcomputer 111 occurs, the camera microcomputer 205 sets the voltage level of the transmission request signal RTS to Low (hereinafter referred to as asserting the transmission request signal RTS), and thus the lens microcomputer 111. To notify the communication request.

When the lens microcomputer 111 detects a communication request due to the voltage level of the transmission request signal RTS changing to Low, the lens microcomputer 111 performs a process of generating the lens data signal DLC to be transmitted to the camera microcomputer 205. Then, when the lens data signal DLC is ready to be transmitted, transmission of the lens data signal DLC for one frame is started via the first data communication channel. Here, the lens microcomputer 111 starts transmission of the lens data signal DLC within a set time mutually set between the camera microcomputer 205 and the lens microcomputer 111 from the time when the voltage level of the communication request signal RTS becomes Low. To do.

That is, in the communication method B, the lens data to be transmitted may be fixed between the time when the voltage level of the communication request signal RTS becomes Low and the time when the transmission of the lens data signal DLC is started. Unlike the communication method A, since there is no strict constraint that the lens data to be transmitted needs to be determined by the time the first clock pulse is input, there is no restriction on the timing of starting transmission of the lens data signal DLC. Can have

Next, the camera microcomputer 205 returns the voltage level of the transmission request signal RTS to High in response to the detection of the start bit ST added to the beginning of the data frame of the lens data signal DLC received from the lens microcomputer 111. Hereinafter, the transmission request signal RTS will be negated. As a result, the transmission request is canceled and the transmission of the camera data signal DCL on the second communication channel is started. It should be noted that the negation of the transmission request signal RTS and the start of transmission of the camera data signal DCL may be performed first, and these may be performed until the reception of the data frame of the lens data signal DLC is completed.

The lens microcomputer 111 that has transmitted the data frame of the lens data signal DLC adds a BUSY frame to the lens data signal DLC when it is necessary to notify the camera microcomputer 205 of the communication standby request BUSY. The camera microcomputer 205 monitors whether or not the communication standby request BUSY has been notified, and while the communication standby request BUSY is being notified, assertion of the transmission request signal RTS for the next transmission request is prohibited.

The lens microcomputer 111 executes necessary processing during the period in which the communication from the camera microcomputer 205 is on standby in response to the communication standby request BUSY, and releases the communication standby request BUSY after the next communication is ready. The camera microcomputer 205 is permitted to assert the transmission request signal RTS for the next transmission request, provided that the communication standby request BUSY is released and the transmission of the data frame of the camera data signal DCL is completed. ..

As described above, in this embodiment, the lens microcomputer 111 sends the data frame of the lens data signal DLC to the camera microcomputer 205 in response to the transmission request signal RTS being asserted triggered by the communication start event in the camera microcomputer 205. To start sending. Then, the camera microcomputer 205 starts transmitting the data frame of the camera data signal DCL to the lens microcomputer 111 in response to detecting the start bit ST of the lens data signal DLC.

Here, the lens microcomputer 111 adds a BUSY frame after the data frame of the lens data signal DLC for the communication standby request BUSY as necessary, and then releases the communication standby request BUSY to perform one frame of communication processing. Complete. By this communication processing, 1-byte communication data is transmitted and received between the camera microcomputer 205 and the lens microcomputer 111.

Next, the communication mode M3 in which communication is performed in the format F2 using the communication method B will be described. FIG. 5A shows a waveform of a communication signal exchanged between the camera microcomputer 205 and the lens microcomputer 111 in the communication mode M3. FIG. 5A shows a waveform of a communication signal when transmitting data of three frames continuously. As described above, in the format F2, adding the communication standby request BUSY to the lens data signal DLC is prohibited.

In the data format of the lens data signal DLC in the communication mode M3, one frame is composed of only data frames, and no BUSY frame exists. Therefore, in the communication mode M3, the communication standby request BUSY from the lens microcomputer 111 to the camera microcomputer 205 cannot be notified.

The format F2 as described above is used for continuous communication with a short interval between frames when transferring a relatively large amount of data between the camera microcomputer 205 and the lens microcomputer 111. That is, the format F2 enables high-speed communication of a large amount of data.

Next, a communication control process between the camera microcomputer 205 and the lens microcomputer 111, which is a feature of this embodiment, will be described. FIG. 5B shows waveforms of communication signals when the camera microcomputer 205 and the lens microcomputer 111 continuously transmit and receive the camera data signal DCL and the lens data signal DLC of n frames, respectively. The camera microcomputer 205 asserts the transmission request signal RTS when an event that starts communication with the lens microcomputer 111 occurs. In the format F2, unlike the format F1, the camera microcomputer 205 does not need to negate the transmission request signal RTS for each frame. Therefore, while the data can be continuously transmitted/received, the assertion state of the transmission request signal RTS is maintained.

When the lens microcomputer 111 detects the communication request by asserting the transmission request signal RTS, the lens microcomputer 111 performs the generation process of the lens data signal DLC to be transmitted to the camera microcomputer 205. When the lens data signal DLC is ready to be transmitted, transmission of the lens data signal DLC (DL1) of the first frame on the first data communication channel is started.

The lens microcomputer 111 that has transmitted the data frame of the lens data signal DLC of the first frame confirms the transmission request signal RTS again. At this time, if the transmission request signal RTS is in the asserted state, the lens microcomputer 111 transmits the lens data signal DLC (DL2) of the next second frame to the camera microcomputer 205 following the first frame in which the transmission is completed. To do. In this way, the lens data signals DLC (DL1 to DLn) from the lens microcomputer 111 are continuously transmitted to the camera microcomputer 205 while the assertion state of the transmission request signal RTS is maintained. Then, when the transmission of the predetermined number of frames n is completed, the transmission of the lens data signal DLC is stopped.

From the camera microcomputer 205, in response to detecting the start bit ST for each frame of the lens data signal DCL from the lens microcomputer 111, in the second communication channel of the camera data signal DCL (DC1 to DCn) of n frames. Transmission starts.

FIG. 5C shows the waveform of the communication signal when the camera microcomputer 205 or the lens microcomputer 111 instructs a temporary communication standby during the communication of continuous data transmission and reception shown in FIG. 5B. There is. Also here, the communication request signal RTS is asserted from the camera microcomputer 205 so that the lens microcomputer 111 starts transmitting the lens data signal DLC, and the camera microcomputer 205 transmits the camera data signal DCL in response to the detection of the start bit ST. To start.

T2w1 indicates a communication standby period in which the communication standby is instructed by the camera microcomputer 205, and the instruction is notified to the lens microcomputer 111 by temporarily negating the transmission request signal RTS. When the lens microcomputer 111 detects that the transmission request signal RTS has been negated, the lens microcomputer 111 completes the transmission of the lens data signal DLC frame (DL6: hereinafter, a rest frame) in the transmission at the time of the detection, and then transmits. Pause.

In response to the suspension of the transmission of the lens data signal DLC, the camera microcomputer 205 also suspends the transmission of the camera data signal DCL after transmitting the frame (DC6) corresponding to the suspension frame in the camera data signal DCL. With such communication control, even if a communication standby instruction is issued during continuous data transmission/reception, the lens data signal DLC and the camera data signal DCL can be managed to have the same number of transmitted frames.

When the communication waiting request event disappears, the camera microcomputer 205 can instruct the lens microcomputer 111 to restart communication by asserting the transmission request signal RTS again. In response to the communication restart instruction, the lens microcomputer 111 restarts transmission of the lens data signal DLC from the frame following the pause frame (DL7: hereinafter referred to as restart frame). Then, in response to the detection of the start bit ST of the restart frame, the camera microcomputer 205 restarts the transmission of the camera data signal DCL from the frame (DC7) corresponding to the restart frame.

On the other hand, T2w2 represents a communication standby period in which the lens microcomputer 111 instructs the communication standby. In the figure, neither the camera microcomputer 205 nor the lens microcomputer 111 is instructed to wait for communication after the end of the communication waiting period T2w1, and the above-described restart frames DL7 and DC7 and the subsequent frames DL8, DC8 to DL9, and DC9 are consecutive in this order. Sending and receiving data.

Then, when the communication standby request event occurs when the transmission of the frame DL9 (reception of the frame DC9 by the camera microcomputer 205) is completed in the lens microcomputer 111, the lens microcomputer 111 instructs the camera microcomputer 205 to perform the communication standby instruction. To notify.

When the transmission request signal RTS is in the asserted state, the lens microcomputer 111 does not transmit the lens data signal DLC, so that the lens microcomputer 111 notifies the camera microcomputer 205 that communication is suspended.

The camera microcomputer 205 constantly monitors the start bit ST of each frame of the lens data signal DLC, and if it does not detect the start bit ST, it decides to stop the transmission of the next frame of the camera data signal DCL. .. If the camera microcomputer 205 does not receive the lens data signal DLC (DL10 in the figure) from the lens microcomputer 111 even if the transmission request signal RTS is asserted, the camera microcomputer 205 suspends communication without transmitting the camera data signal DCL (DC10). To do. The camera microcomputer 205 maintains the transmission request signal RTS in the asserted state during the communication standby period T2w2 instructed by the lens microcomputer 111.

Then, the communication standby request event disappears in the lens microcomputer 111, and the lens microcomputer 111 restarts the transmission of the restart frame DL10 of the lens data signal DLC. The camera microcomputer 205 restarts the transmission of the corresponding frame DC10 in the camera data signal DCL in response to detecting the start bit ST of the restart frame DL10.

Next, a procedure for determining a communication format performed between the camera microcomputer 205 and the lens microcomputer 111 will be described with reference to FIG. The camera microcomputer 205 and the lens microcomputer 111 perform the communication control shown in the flowcharts of FIGS. 6 and 7 according to the communication control program which is a computer program. 6 and 7, "S" means a step.

First, when the interchangeable lens 100 is attached to the camera body 200, in step S100 and step S200, the camera microcomputer 205 and the lens microcomputer 111 set the communication format to the initial communication format in which the establishment of communication is guaranteed. Here, the initial communication format may be a combination of the communication method and the data format disclosed in this embodiment, or may be another communication format. When the start-stop synchronization communication format is selected as the initial communication format, it is preferable to set the BUSY identification position P so that communication can be executed regardless of which camera and interchangeable lens are combined.

Subsequently, in step S101, the camera microcomputer 205 transmits camera identification information indicating a communication format compatible with the camera body 200 to the lens microcomputer 111. Further, in step S202, the lens microcomputer 111 transmits lens identification information indicating a communication format compatible with the interchangeable lens 100 to the camera microcomputer 205.

Here, the “identification information” includes information indicating which of the clock synchronization type and the start/stop synchronization type communication system is supported, and information indicating the range of communication bit rates that can be supported. Information indicating the BUSY identification position P is also included in the identification information.

The camera microcomputer 205 receives the lens identification information in step S102. The lens microcomputer 111 receives the camera identification information in step S201. Here, in the flowchart of FIG. 6, the lens identification information is transmitted after the camera identification information is transmitted, but the camera identification information and the lens identification information may be transmitted at the same time. Further, the camera identification information may be transmitted after the lens identification information is transmitted.

Subsequently, in steps S103 and S203, the communication format is set in the subsequent communication. Specifically, the camera microcomputer 205 and the lens microcomputer 111 determine the fastest communication bit rate among the communication bit rates compatible with each other as the communication bit rate. Further, among the BUSY identifying positions which can correspond to each other, the position closest to the stop bit SP is set as the BUSY identifying position.

Next, the data communication flow in the asynchronous communication system will be described with reference to FIG. In FIG. 7, a communication flow in the data format in which the BUSY signal is permitted to be added will be described.

The camera microcomputer 205 monitors whether or not a communication event for starting communication with the lens microcomputer 111 has occurred, and when a communication event has occurred in step S110, the process proceeds to step S111. In step S111, the communication request signal RTS is asserted to make a communication request to the lens microcomputer 111, as described above.

The lens microcomputer 111 monitors whether the communication request signal RTS is asserted, and when recognizing that the communication request signal RTS is asserted in step S210, the process proceeds to step S211. In step S211, the lens microcomputer 111 transmits the lens data signal DLC to the camera microcomputer 205 via the first data communication channel.

Upon receiving the lens data signal DLC from the lens microcomputer 111 (YES in step S112), the camera microcomputer 205 proceeds to step S113 and negates the communication request signal RTS. Then, in step S114, the camera data signal DCL is transmitted to the lens microcomputer 111 via the second data communication channel.

When the lens microcomputer 111 detects the reception start of the camera data signal DCL in step S212, the lens microcomputer 111 proceeds to step S213 to perform the reception processing of the camera data signal DCL. In parallel with the processing of step S213, in step S214, it is determined whether or not it is necessary to notify the camera microcomputer 205 of the communication standby request BUSY. If it is not necessary to notify the communication standby request BUSY, the process proceeds to step S218 and waits until the reception of the camera data signal DCL is completed.

On the other hand, when it is necessary to notify the camera microcomputer 205 of the communication standby request BUSY from the lens microcomputer 111, the process proceeds to step S215, and a BUSY frame is added to the lens data signal DLC. The lens microcomputer 111 executes necessary processing while notifying the communication standby request BUSY, and releases the communication standby request BUSY after the next communication is ready (Yes in step S216) (step S217). After canceling the communication standby request BUSY, the process proceeds to step S218 and waits until the reception of the camera data signal DCL is completed. When the reception of the camera data signal DCL is completed (Yes in step S218), the process returns to step S210 to continue monitoring whether the communication request signal RTS is asserted.

Upon receiving the notification of the communication standby request BUSY in step S115, the camera microcomputer 205 waits until the communication standby request BUSY is released. When the communication standby request BUSY is canceled (YES in step S116), the process proceeds to step S117 to determine whether the transmission of the camera data signal DCL is completed. Further, even when the communication standby request BUSY is not notified in step S115, the process proceeds to step S117, and it is determined whether or not the transmission of the camera data signal DCL is completed. When it is determined in step S117 that the transmission of the camera data signal DCL is completed, the process returns to step S110, and the monitoring of whether a communication event has occurred is continued.

As described above, the present embodiment relates to communication control in start-stop synchronization (communication method B) communication including three channels. A communication standby request BUSY is transmitted from the lens microcomputer 111 to the camera microcomputer 205 via the first data communication channel which is a dedicated output channel of the lens microcomputer 111. On the other hand, the transmission request signal RTS from the camera microcomputer 205 is transmitted from the camera microcomputer 205 to the lens microcomputer 111 via the notification channel as a dedicated output channel of the camera microcomputer 205.

As described above, the communication standby request BUSY from the lens microcomputer 111 is transmitted/received via the dedicated output channel of the lens microcomputer 111, and the transmission request signal RTS from the camera microcomputer 205 is transmitted/received via the dedicated output channel of the camera microcomputer 205. To be done. As a result, the communication invalid period between the camera microcomputer 205 and the lens microcomputer 111 can be shortened, and as a result, the effective communication speed can be increased.

Regarding the communication start timing, data transmission from the lens microcomputer 111 to the camera microcomputer 205 is started first. The camera microcomputer 205 starts data transmission in response to detecting the start bit ST of the data frame transmitted from the lens microcomputer 111. By setting the communication start timing in this way, it is possible to give the lens microcomputer 111, which has received the transmission request signal RTS, a timing at which data transmission to the camera microcomputer 205 starts.

For example, the start timing of data transmission can be changed according to the information processing capability of the lens microcomputer 111. As a result, the communication speed between the camera body 200 and the interchangeable lens 100 can be improved without causing communication failure.

The embodiments described above are merely representative examples, and various modifications and changes can be made to the embodiments when implementing the present invention. For example, in the above-described embodiment, the example in which the interchangeable lens is used as the accessory device is shown, but a strobe or the like may be used as long as it has a communication function with the imaging device.

100 interchangeable lens 111 lens microcomputer 112a, 112b lens communication unit 200 camera body 205 camera microcomputer 208a, 208b camera communication unit

Claims (25)

An accessory device detachable from an imaging device,
An accessory including a channel including a notification channel used for notification from the imaging device to the accessory device and an accessory data communication channel used for data transmission from the accessory device to the imaging device, between the imaging device A communication unit, and an accessory control unit that controls the accessory communication unit,
The accessory control unit transmits data to the imaging device via the accessory data communication channel in response to receiving a transmission request signal requesting data transmission from the accessory device to the imaging device,
The accessory device, wherein the accessory control unit transmits a communication standby request signal for preventing the transmission request signal from being transmitted from the imaging device to the accessory device, to the imaging device. The channel provided between the imaging device and the accessory device is composed of the notification channel, the accessory data communication channel, and an imaging device data communication channel used for data transmission from the imaging device to the accessory device. The accessory device according to claim 1, wherein: The start of transmission of the communication standby request signal is represented by changing a voltage level of the accessory data communication channel from a first level to a second level lower than the first level. Item 2. The accessory device according to Item 1 or 2. 4. The accessory control unit ends the transmission of the communication standby request signal by changing the voltage level of the accessory data communication channel from the second level to the first level. The accessory device according to. The accessory device according to claim 1, wherein the accessory device performs asynchronous communication with the imaging device. The accessory control unit transmits the communication standby request signal to the imaging device by adding the communication standby request signal to a data frame transmitted via the accessory data communication channel. The accessory device according to. The accessory device communicates with the imaging device by switching between a data format in which data frames are continuously transmitted without providing a communication standby period and a data format in which data frames are intermittently transmitted with a communication standby period provided. The accessory device according to claim 5 or 6, characterized in that. The accessory device is capable of communicating with the imaging device by switching the communication system between a clock-synchronous communication system synchronized with a clock signal and an asynchronous communication system.
The accessory control unit receives the clock signal transmitted from the imaging device via the notification channel in the clock synchronous communication, and transmits the clock signal via the notification channel in the start/stop communication. The accessory device according to claim 1, wherein the accessory device receives a request signal. 9. The accessory control unit transmits the communication standby request signal to the imaging device via the notification channel while the clock-synchronous communication method is set. Accessory equipment. The accessory device according to any one of claims 1 to 9, wherein the transmission request signal is represented by changing a voltage of the notification channel. The accessory device according to claim 1, further comprising a photographing optical system capable of forming a subject image with respect to an image sensor included in the image pickup device. An imaging device to which an accessory device is detachably mounted,
Imaging with a channel including a notification channel used for notification from the imaging device to the accessory device and an accessory data communication channel used for data transmission from the accessory device to the imaging device, between the accessory device An apparatus communication unit, and an imaging apparatus control unit that controls the imaging apparatus communication unit,
The imaging device control unit transmits a communication standby request signal for preventing transmission of a transmission request signal requesting data transmission from the accessory device to the imaging device, from the accessory device via the accessory data communication channel. The image pickup apparatus, wherein the transmission request signal is not transmitted to the accessory device while receiving. The channel provided between the imaging device and the accessory device is composed of the notification channel, the accessory data communication channel, and an imaging device data communication channel used for data transmission from the imaging device to the accessory device. The image pickup apparatus according to claim 12, wherein The image pickup device control unit starts data transmission to the accessory device after receiving data transmitted from the accessory device in response to the transmission request signal. Imaging device. The start of reception of the communication standby request signal is represented by changing a voltage level of the accessory data communication channel from a first level to a second level lower than the first level. Item 15. The image pickup device according to any one of items 12 to 14. The imaging device control unit cancels the communication standby state in which the transmission request signal is not transmitted in response to the voltage level of the accessory data communication channel being changed from the second level to the first level. The image pickup apparatus according to claim 15, wherein The image pickup apparatus according to any one of claims 12 to 16, wherein the image pickup apparatus control unit performs start-stop synchronization communication with the accessory apparatus. The imaging apparatus according to claim 17, wherein the communication standby request signal is added to a data frame received from the accessory device via the accessory data communication channel. The imaging device communicates with the accessory device by switching between a data format for continuously transmitting data frames without a communication standby period and a data format for intermittently transmitting data frames with a communication standby period. The imaging device according to claim 17 or 18, characterized in that. The imaging device is capable of communicating with the accessory device by switching the communication system between a clock-synchronous communication system synchronized with a clock signal and a start-stop synchronization communication system,
The imaging device control unit transmits the clock signal to the accessory device via the notification channel in the clock synchronous communication, and the transmission request signal via the notification channel in the start/stop synchronous communication. 20. The image pickup device according to claim 17, wherein the image pickup device is transmitted to the accessory device. 21. The imaging device according to claim 20, wherein the communication standby request signal is received by the imaging device via the notification channel while the clock-synchronous communication system is set. 22. The imaging device according to claim 1, wherein the imaging device control unit transmits the transmission request signal to the accessory device by changing a voltage of the notification channel. An accessory device that is attachable to and detachable from an imaging device, a notification channel used for notification from the imaging device to the accessory device, and data transmission from the accessory device to the imaging device. Provided with a channel including an accessory data communication channel used for, a transmission request signal requesting data transmission from the accessory device to the imaging device, in response to receiving from the imaging device via the notification channel, To a computer of an accessory device that transmits data to the imaging device via the accessory data communication channel,
Controlling the transmission of a communication standby request signal to the image pickup device to prevent the transmission request signal from being transmitted from the image pickup device to the accessory device via the accessory data communication channel. Communication control program An imaging device to which an accessory device is detachably mounted, a notification channel used for notification from the imaging device to the accessory device, and data from the accessory device to the imaging device. A computer of an imaging device that includes a channel including an accessory data communication channel used for transmission, and transmits a transmission request signal requesting data transmission from the accessory device to the imaging device to the accessory device via the notification channel. To
A control for not transmitting the transmission request signal to the accessory device while the communication standby request signal for preventing the transmission request signal from being transmitted from the accessory device via the accessory data communication channel. A communication control program characterized by being executed. An imaging system including an imaging device and an accessory device detachable from the imaging device,
The accessory device includes a notification channel used for notification from the imaging device to the accessory device and an accessory data communication channel used for data transmission from the accessory device to the imaging device, between the accessory device and the imaging device. An accessory communication unit that provides a channel including the accessory communication unit, and an accessory control unit that controls the accessory communication unit,
The image pickup device includes an image pickup device communication unit that provides a channel including the notification channel and the accessory data communication channel between the accessory device and an image pickup device control unit that controls the image pickup device communication unit. Have,
The imaging device control unit transmits a transmission request signal requesting data transmission from the accessory device to the imaging device, to the accessory device via the notification channel,
The accessory control unit transmits data to the imaging device via the accessory data communication channel in response to receiving the transmission request signal,
The accessory control unit transmits a communication standby request signal to the imaging device control unit via the accessory data communication channel to prevent the transmission request signal from being transmitted from the imaging device to the accessory device. An imaging system characterized by the above.

Images