Imaging apparatus and accessory device

An imaging apparatus includes: a first camera communication control unit configured to transmit, from the imaging apparatus to the accessory device, a control command for controlling operations of the accessory device, via a first communication channel provided between the imaging apparatus and the accessory device, and receive data transmitted from the accessory device in response to the control command; and a second camera communication control unit configured to receive optical data of the accessory device transmitted from the accessory device, via a second communication channel provided between the imaging apparatus and the accessory device separate from the first communication channel.

BACKGROUND OF THE INVENTION

Field of the Disclosure

The present invention relates to an imaging device (hereinafter referred to as “camera body”) and an accessory device such as an interchangeable lens or the like, that are communicable with each other.

Description of the Related Art

In an accessory interchanging camera system, including a camera body from which accessory devices are detachable, communication is performed for the camera body to control operations of the accessory device, and for the accessory device to provide data necessary for that control and for imaging to the camera body. Particularly, in a case of imaging moving images for recording or moving images for live view display using an interchangeable lens, smooth lens control matching the imaging cycle is required. Accordingly, the imaging timing of the camera body and the control timing of the interchangeable lens need to be synchronized. To this end, the camera body needs to complete reception of data from the interchangeable lens and transmission of various types of commands, requests, and so forth, to the interchangeable lens, within an imaging cycle. However, increase in the data amount that the camera body receives from the interchangeable lens, and shortening of the imaging cycle (higher frame rates) has led to the need for even faster communication of large amounts of data.

Japanese Patent Laid-Open No. 2013-182118 discloses a camera system that performs data transmission using two lines that originally were provided for bidirectional communication as two lines for one-way communication, in order to transmit great amounts of data from the interchangeable lens to the camera body at high speeds. Japanese Patent No. 5,517,486 discloses a camera system where, when performing asynchronous communication between the camera body and interchangeable lens, the interchangeable lens serves as a communication master to arbitrate data transmission to the camera body.

In the camera system disclosed in Japanese Patent Laid-Open No. 2013-182118, while great amounts of data can be transmitted from the interchangeable lens to the camera body, control commands cannot be transmitted from the camera body to the interchangeable lens during this data transmission. That is to say, transmission of control commands from the camera body instructing operations at the interchangeable lens, such as driving the diaphragm or focusing ring or the like, must wait until transmission of data from the interchangeable lens to the camera body ends. As a result, the timing at which operations of the interchangeable lens are performed in response to the control commands are delayed.

On the other hand, in the camera system disclosed in Japanese Patent No. 5,517,486, the interchangeable lens that is the communication master transmits data to the camera body at a desired timing, and transmission of control commands from the camera body to the interchangeable lens is permitted by interrupting transmission of the data. According to this, delay of transmission of control commands form the camera body to the interchangeable lens can be avoided, but transmission of data from the interchangeable lens to the camera body will be delayed.

SUMMARY OF THE INVENTION

It has been found desirable to provide an imaging apparatus and accessory device where control commands can be transmitted from the imaging apparatus to the accessory device without delay, while transmitting great amounts of data from the accessory device to the imaging apparatus at high speed.

According to one aspect of the present invention, an imaging apparatus to which an accessory device is detachably mounted, includes: a first camera communication control unit configured to transmit, from the imaging apparatus to the accessory device, a control command for controlling operations of the accessory device, via a first communication channel provided between the imaging apparatus and the accessory device, and receive data transmitted from the accessory device in response to the control command; and a second camera communication control unit configured to receive optical data of the accessory device transmitted from the accessory device, via a second communication channel provided between the imaging apparatus and the accessory device separate from the first communication channel. The first camera communication control unit transmits, to the accessory device, a data specification command specifying the optical data of which transmission is requested, via the first communication channel.

Another aspect of the present invention is an accessory device detachably mounted to the above-described imaging apparatus. The optical data is transmitted via the second communication channel, in response to the control command received from the imaging apparatus via the first communication channel.

Another aspect of the present invention is an accessory device to which an imaging apparatus is detachably mounted. The accessory device includes: a first accessory communication control unit configured to receive, via a first communication channel provided between the accessory device and the imaging apparatus, a control command from the imaging apparatus for controlling operations of the accessory device, and transmitting data to the imaging apparatus from the accessory device in response to the control command; a second accessory communication control unit configured to transmit optical data of the accessory device, via a second communication channel provided between the accessory device and the imaging apparatus separate from the first communication channel. The second accessory communication control unit transmits optical data in response to a data specification command, specifying the optical data of which the imaging apparatus requests the accessory device for transmission, which the first accessory communication control unit has received from the imaging apparatus.

Another aspect of the present invention is an imaging apparatus to which an accessory device is attachable. The imaging apparatus includes a first communication line configured to transmit a timing signal corresponding to a timing of communication with the accessory device, a second communication line configured to transmit a first command relating to operations of the accessory device at a timing corresponding to the timing signal, a third communication line configured to receive data corresponding to the first command at a timing corresponding to the timing signals, a fourth communication line configured to receive data regardless of timing indicated by the timing signal, and a communication control unit configured to control communication by the first communication line, the second communication line, the third communication line, and the fourth communication line.

Another aspect of the present invention is an accessory device detachably mounted to the imaging apparatus. The optical data is transmitted to the imaging apparatus via the fourth communication line in accordance with the second command received from the imaging apparatus via the second communication line.

Another aspect of the present invention is an accessory device attachable to an imaging apparatus, including a first communication line configured to receive a timing signal corresponding to a timing of communication with the imaging apparatus, a second communication line configured to receive a first command relating to operations of the accessory device, at a timing corresponding to the timing signal, a third communication line configured to transmit data corresponding to the first command, at a timing corresponding to the timing signal, a fourth communication line configured to transmit data, regardless of timing indicated by the timing signal, and a communication control unit configured to control communication over the first communication line, the second communication line, the third communication line, and the fourth communication line.

DESCRIPTION OF THE EMBODIMENTS

First Embodiment

FIG. 1exemplarily illustrates the configuration of an imaging system (hereinafter referred to as “camera system”) including a camera body200serving as an imaging apparatus, and an interchangeable lens100serving as an accessory device detachably mounted thereto, as a first embodiment of the present invention. Although the interchangeable lens100is exemplarily illustrated as the accessory device in the present embodiment, the present invention can be applied to devices other than interchangeable lenses, as long as the device is directly or indirectly connectable to the camera body200, and can communicate with the camera body200.

The camera body200has an imaging device201, such as a charge-coupled device (CCD) sensor, complementary metal-oxide semiconductor (CMOS) sensor, or the like, and the interchangeable lens100has an imaging optical system that forms an image of an object on the imaging device201. The camera body200and interchangeable lens100) use three-line clock synchronous communication or asynchronous communication to transmit control commands from the camera body200to the interchangeable lens100as first commands. A control command is a signal controlling (instructing) zooming operations, light amount adjustment operations, focusing operations, and image stabilization operations. The interchangeable lens100transmits data (also referred to as “first data”) to the camera body200, in response to control commands received from the camera body200.

Further, the interchangeable lens100transmits optical data of the interchangeable lens100(an example of second data) to the camera body200. Optical data includes optical state data indicating the optical state, such as focal length of the photographing optical system, aperture diameter, position of focus lens, and so forth, within the interchangeable lens100, and optical correction data such as focus correction data necessary for autofocus (AF). This optical data is transmitted to the camera body200, in accordance with data specification commands, serving as second commands, that are transmitted from the camera body200to the interchangeable lens100.

A specific configuration of the interchangeable lens100and camera body200will be described. The interchangeable lens100and camera body200are mechanically and electrically connected via a mount300that is a joining mechanism. The interchangeable lens100is supplied with electric power source from the camera body200via an electric power source terminal portion (omitted from illustration) provided at the mount300, and operates various types of actuators and a lens microprocessor111. The interchangeable lens100and camera body200also perform communication with each other via a communication terminal portion (illustrated inFIG. 2) that is provided at the mount300.

The imaging optical system of the interchangeable lens100includes, in order from the side of an object OBJ, a field lens101, a zoom lens102for zooming, an aperture unit114that adjusts the amount of light, an image stabilizing lens103, and a focus lens104for focusing. The zoom lens102and focus lens104are held by lens holding frames105and106, respectively. The lens holding frames105and106are movably guided in the optical axis direction indicated inFIG. 1by a dashed line, by a guide shaft omitted from illustration, and respectively are driven in the optical axis direction by a zoom actuator107and focus actuator108, which are configured of stepping motors. The zoom actuator107and focus actuator108respectively move the zoom lens102and focus lens104, synchronously with driving pulses.

The image stabilizing lens103reduces image blurring due to shaking of hands holding the camera or the like, or shaking of the camera, by moving (shifting) in a direction orthogonal to the optical axis of the imaging optical system. The camera system according to the present embodiment can also perform image stabilization control by the camera body200and interchangeable lens100communicating in order for the camera body200and interchangeable lens100to coordinate with each other and further raise image stabilization effects. These coordinated operations need communication processing with high real-time performance between the camera body200and interchangeable lens100. Specifically, the interchangeable lens100transmits, to the camera body200, information of camera shaking detected by a shake sensor such as a vibrating gyroscope or the like (omitted from illustration), provided within the interchangeable lens100, within a charge accumulation period of the imaging device201when imaging at the camera body200. The interchangeable lens100also receives information of motion vectors from the camera body200, so as to be in time for image stabilizing driving where the image stabilizing lens103is shifted. In order to realize such high real-time performance in the present embodiment, a later-described first communication channel and second communication channel are separately provided. Note that “communication channel” as used in the present embodiment means an increment of communication path for realizing desired communication functions, and each communication channel is configured of one or more communication lines.

The lens microprocessor111is an accessory control unit that controls operations of various parts within the interchangeable lens100. The lens microprocessor111communicates with a camera microprocessor205in the camera body200, via a first lens communication unit112aserving as a first accessory communication control unit, and a second lens communication unit112bserving as a second accessory communication control unit. InFIG. 1, the first lens communication unit112ais written as “first lens communication unit”, and the second lens communication unit112bis written as “second lens communication unit”. The first lens communication unit112aforms a first communication channel (hereinafter “first communication channel”) with the camera microprocessor205. The second lens communication unit112bforms a second communication channel (hereinafter “second communication channel”) with the camera microprocessor205.

The lens microprocessor111receives control commands, and data specification commands (later-described registration No. commands) specifying optical data which the lens microprocessor111is requested to transmit, which are transmitted from the camera microprocessor205via the first communication channel, at the first lens communication unit112a. The lens microprocessor111also transmits data as a response to the above control commands from the first lens communication unit112ato the camera microprocessor205via the first communication channel. On the other hand, the lens microprocessor111transmits the above optical data from the second lens communication unit112bto the camera microprocessor205via the second communication channel. The lens microprocessor111controls communication with the camera microprocessor205in accordance with a communication control program that is a computer program.

Specifically, the lens microprocessor111causes a zoom drive circuit119and a focus drive circuit120to respectively drive the zoom actuator107and focus actuator108, in accordance with control commands from the camera microprocessor205regarding zooming and focusing operations. Accordingly, zooming processing where zooming operations by the zoom lens102are controlled, and autofocus (AF) processing where focusing operations by the focus lens104are controlled, are carried out.

The interchangeable lens10) has a manual focus ring130that can be rotationally operated by the user, and a focus encoder131that detects the rotation operation amount of this manual focus ring130. The lens microprocessor111causes the focus drive circuit120to drive the focus actuator108and move the focus lens104in accordance with the rotation operation amount of the manual focus ring130detected by the focus encoder131. Thus, manual focus (MF) is carried out.

The aperture unit114has aperture blades114aand114b, and an aperture actuator113that moves these so as to open and close. The state (position) of the aperture blades114aand114bis detected by a Hall effect device115, and output signals from the Hall effect device115are input to the lens microprocessor111via an amplifying circuit122and an A/D conversion circuit123. The lens microprocessor111causes an aperture drive circuit121to drive the aperture actuator113based on input signals from the A/D conversion circuit123. The lens microprocessor111causes the aperture drive circuit121to drive the aperture actuator113in accordance with control commands regarding light amount adjustment operations from the camera microprocessor205. Accordingly, light amount adjustment processing where light amount adjustment operations of the aperture unit114are control is performed.

Further, the lens microprocessor111drives an image stabilization armature126via an image stabilization drive circuit125in accordance with shaking detected by an unshown shaking sensor such as a vibrating gyroscope or the like, provided in the interchangeable lens100. The lens microprocessor111causes the image stabilization drive circuit125to drive the image stabilization armature126in response to control commands regarding image stabilization operations from the camera microprocessor205. Accordingly, image stabilization processing is performed where image stabilization operations of the image stabilizing lens103being moved to reduce (correct) blurring are controlled.

The camera body200has the above-described imaging device201, an A/D conversion circuit202, a signal processing circuit203, a recording unit204, the camera microprocessor205, and a display unit206. The imaging device201performs photoelectric conversion of a subject image formed by the imaging optical system within the interchangeable lens100, and outputs electric signals (analog signals). The A/D conversion circuit202converts the analog signals from the imaging device201into digital signals.

The signal processing circuit203performs various types of image processing on the digital signals from the A/D conversion circuit202and generates image signals. The signal processing circuit203also generates focus information indicating the contrast state of the subject image, i.e., the focus state of the imaging optical system, and luminance information representing the exposure state, from the image signals. The signal processing circuit203outputs the image signals to the display unit206, and the display unit206displays the image signals as a live view image used to confirm composition, focus state, and so forth. The signal processing circuit203also outputs the image signals to the recording unit204, and the recording unit204records the image signals.

An image processing unit209performs correction processing on the image signals generated by the signal processing circuit203, for correction of various types of aberration. The image processing unit209includes a motion vector detecting unit210. The motion vector detecting unit210detects motion vectors among multiple frame images making up the image signals generated by the signal processing circuit203. The information of motion vectors detected in this way is transmitted to the lens microprocessor111via the first communication channel, as a part of control commands regarding image stabilization operations, and is reflected in image stabilization processing.

The camera microprocessor205serving as a camera control unit controls the camera body200in accordance with input from a camera operating unit207that includes an imaging instruction switch that is omitted from illustration, and various types of settings switches and so forth. The camera microprocessor205communicates with the lens microprocessor111via a first camera communication unit208aserving as a first camera communication control unit, and a second camera communication unit208bserving as a second camera communication unit. InFIG. 1, The first camera communication unit208ais written as “first camera communication unit”, and the second camera communication unit208bis written as “second camera communication unit”. The first camera communication unit208aforms the above-described first communication channel with the lens microprocessor111, and the second camera communication unit208bforms the above-described second communication channel with the lens microprocessor111.

The camera microprocessor205transmits control commands regarding zoom operations in accordance with operations of a zoom switch that is omitted from illustration, to the lens microprocessor111from the first camera communication unit208avia the first communication channel. In the same way, the camera microprocessor205transmits control commands regarding focus operations in accordance with light amount adjustment operations of the aperture unit114according to luminance information and focus operations of the focus lens104according to focus information, to the lens microprocessor111via the first communication channel. The camera microprocessor205controls communication with the lens microprocessor111following a communication control program that is a computer program.

Next, the configuration of the first and second communication channels provided between the camera microprocessor205and lens microprocessor111will be described in detail, with reference toFIG. 2. The aforementioned mount300is provided with communication terminal portions301through304. The first camera communication unit208ais connected to three communication terminal portions301through303via a first camera communication interface circuit208c. The first lens communication unit112ais connected to the communication terminal portions301through303via a first lens communication interface circuit112c. Accordingly, this forms the first communication channel made up of three lines (three communication lines). The first communication channel performs communication by a communication method realized by three lines, such as three-line clock synchronous communication and asynchronous communication (using at least two lines). In the following, the first communication channel performs three-line clock synchronous communication.

The second camera communication unit208bis connected to one communication terminal portion304via a second camera communication interface circuit208d. The second lens communication unit112bis connected to the communication terminal portion304via the second lens interface circuit112d. Accordingly, this forms the second communication channel made up of one line (one communication line). The second communication channel performs communication by a communication method realized by on line. In the following, the second communication channel performs asynchronous communication.

The first communication channel is made up of a clock communication line (LCLK) serving as a first communication line, a camera-lens communication line (DCL) serving as a second communication line, and a first lens-camera communication line (DLC) serving as a third communication line. The clock communication line is a communication line that supplies clock signals, serving as timing signals for obtaining data from the camera microprocessor205that is the communication master for the lens microprocessor111. Communication by the camera-lens communication line (DCL) and communication by the first lens-camera communication line (DLC) are each performed at timings corresponding to these clock signals. This, the clock signals are signals that control timing for communication by the camera-lens communication line (DCL) and communication by the first lens-camera communication line (DLC).

The camera-lens communication line is a communication line for transmitting various types of commands, such as the above-described control commands and data specification commands (including requests) from the camera microprocessor205to the lens microprocessor111. The first lens-camera communication line is a communication line for transmitting various types of notifications, such as responses as to the various types of commands that the lens microprocessor111has received from the camera microprocessor205, and so forth, to the camera microprocessor205.

The various types of commands transmitted from the camera microprocessor205to the lens microprocessor111also include rate specification commands. In order to asynchronous communication to be established on the second communication channel, the communication speed (communication bitrate) for performing communication between the camera microprocessor205and lens microprocessor111needs to be agreed on beforehand, and communication needs to be performed following this agreement. In the present embodiment, the communication bitrate is shared between the camera microprocessor205and lens microprocessor111as an agreement, by the camera microprocessor205transmitting (instructing) a rate specification command serving as a command specifying this communication bitrate to the lens microprocessor111. The communication bitrate indicates the amount of data that can be transferred per second, and the unit thereof is bps (bits per second).

Various types of notifications transmitted from the lens microprocessor111to the camera microprocessor205include responses indicating reception of control commands and the driving state of actuators driven in accordance with the control commands, and notification bitrates that can be realized on the second communication channel. In a case where a communication abnormality has occurred on the second communication channel, an abnormality notification to the camera microprocessor205is also included.

The second communication channel is configured of a single second lens-camera communication line (DLC2) serving as a fourth communication line. This second lens-camera communication line is a channel for transmitting the above-described optical data of the interchangeable lens100from the lens microprocessor111to the camera microprocessor205. Although the second communication channel is configured of only one second lens-camera communication line in the present embodiment, the communication cannel may be configured of multiple second lens-camera communication lines. The second communication channel is configured of only one second lens-camera communication line in the present embodiment in order to maximally reduce the number of communication terminal portions provided to the mount300and prevent the mount300from becoming large.

The lens microprocessor111serves as a communication master to control timing of the communication performed at the second communication channel, and communication can be performed at a timing not dependent on the timing of communication by the first communication channel. More specifically, communication by the second lens-camera communication line can be performed at a timing regardless of timings corresponding to clock signals transmitted from the camera microprocessor205to the lens microprocessor111via the clock communication line.

Note that in the present embodiment, the lens microprocessor111and camera microprocessor205perform communication via the first communication channel and communication via the second communication channel, in parallel. In this case, information that the lens microprocessor111transmits via the second communication channel is different information from information transmitted via the first communication channel. In other words, the lens microprocessor111transmits data, other that data transmitted via the first communication channel, via the second communication channel.

The camera body200according to the present embodiment can also mount interchangeable lenses that have communication functions via the first communication channel but do not have communication functions via the second communication channel. In this case, the camera microprocessor205and interchangeable lens perform transmission/reception of various types of commands from the camera microprocessor205to the interchangeable lens, and transmission/reception of the above-described responses to the camera microprocessor205and optical data, via only the first communication channel.

FIG. 3illustrates the configuration of the first and second camera communication units208aand208b, and the first and second lens communication units112aand112b, in further detail. In the first camera communication unit208a, a clock generator (CLK_GENERATOR)310generates the above-described clock signals, and outputs to the clock channel (LCLK) of the first communication channel. A transmission data buffer (Tx_RAM)311is memory storing various types of commands, such as control commands to be transmitted to the lens microprocessor111via the camera-lens communication channel (DCL) of the first communication channel, and is made up of random access memory (RAM) or the like. A transmission parallel/serial converter314convers various types of commands, stored in the transmission data buffer311as parallel data, into serial data and outputs to the camera-lens communication channel (DCL).

A reception serial/parallel converter315converts notifications transmitted as serial data from the lens microprocessor111via the first lens-camera communication line (DLC) of the first communication channel into parallel data. A reception data buffer (Rx_RAM1)312is memory storing notifications as parallel data from the reception serial/parallel converter315, and is made up of RAM or the like.

A camera buffer control unit (RAM_CTRL)313controls the transmission data buffer311and the reception data buffer312of the first camera communication unit208a, and also controls a data reception buffer (Rx_RAM2)330of the second camera communication unit208b. In the second camera communication unit208b, a reception serial/parallel converter331converts optical data that is serial data transmitted from the lens microprocessor111via the second lens-camera communication channel (DLC2) of the second communication channel, into parallel data. The data reception buffer (Rx_RAM2)330is memory that stores optical data that is parallel data from the reception serial/parallel converter331, and is made up of RAM or the like.

In the first lens communication unit112a, a clock detection unit (CLK_DETECT)321detects clock signals input via the clock communication line of the first communication channel. A reception serial/parallel converter319converts various types of commands that are serial data, transmitted from the camera microprocessor205via the camera-lens communication line (DCL) of the first communication channel, into parallel data. A reception data buffer (Rx_RAM)316is memory that stores various types of commands that are parallel data from the reception serial/parallel converter319, and is made up of RAM or the like. A transmission data buffer (Tx_RAM)317is memory that stores notifications to be transmitted to the camera microprocessor205via the camera-lens communication line (DCL) of the first communication channel, and is made up of RAM or the like. A transmission parallel/serial converter320converts notifications, stored in the transmission data buffer317as parallel data, into serial data, and outputs to the first lens-camera communication line.

A lens buffer control unit (RAM_CTRL)318controls the reception data buffer316and transmission data buffer317of the first lens communication unit112a, and also control a data transmission buffer (Tx_RAM2)333of the second lens communication unit112b.

In the second lens communication unit112b, a transmission data buffer control unit (Tx_RAM2)333is memory that stores optical data to be transmitted to the camera microprocessor205via the second lens-camera communication line (DLC2) of the second communication channel, and is made up of RAM or the like. A transmission parallel/serial converter332converts optical data, stored in the data transmission buffer333as parallel data, into serial data, and outputs to the second lens-camera communication line (DLC2).

Data that is various types of commands transmitted from the camera microprocessor205to the lens microprocessor111over the first communication channel are first set in the transmission data buffer311from the camera microprocessor205. For example, data of a control command instructing a focusing operation is made up of multiple bytes indicating focusing drive amount, focusing drive speed, and so forth, and first is written to the transmission data buffer311of the first camera communication unit208a. The buffer control unit313causes the transmission data buffer311to output data to be transmitted, one byte at a time. The transmission parallel/serial converter314converts the output data from parallel data into serial data. The data that has been converted into serial data is then transmitted to the lens microprocessor111over the camera-lens communication line (DCL).

The data transmitted to the lens microprocessor111over the camera-lens communication line (DCL) is converted from serial data into parallel data at the reception serial/parallel converter319of the first lens communication unit112a. The buffer control unit318stores this parallel data in the reception data buffer316. The clock detection unit (CLK_DETECT)321detects clock signals output from the clock control unit310at the camera microprocessor205side when receiving the serial data, and detects reception data synchronously with this clock signal.

In a case of transmitting data as notifications from the lens microprocessor111to the camera microprocessor205via the first communication channel, first, this data is set in the transmission buffer317at the first lens communication unit112a. For example, data made up of multiple bytes is written to the transmission data buffer317, as a response indicating the drive state of the focus actuator. The buffer control unit313then causes the transmission data buffer317to output the data to be transmitted, one byte at a time, in accordance with the clock detecting unit316detecting clock signals. The transmission parallel/serial converter320converts the output data from parallel data into serial data. The data that has been converted into serial data is then transmitted to the camera microprocessor205over the first lens-camera communication line (DLC).

The data that has been transmitted to the camera microprocessor205over the first lens-camera communication line (DLC) is converted from serial data into parallel data at the reception serial/parallel converter315of the first camera communication unit208a. The buffer control unit313stores this parallel data in the reception data buffer312.

Thus, transmission of various types of commands, such as control commands from the camera microprocessor205to the lens microprocessor111via the first communication channel, and notification such as response to the control commands and so forth, from the lens microprocessor111to the camera microprocessor205, are performed.

On the other hand, only the second lens-camera communication channel (DLC2) for one-way data communication from the lens microprocessor111to the camera microprocessor205is provided for the second communication channel. Accordingly, asynchronous communication, where the lens microprocessor111and camera microprocessor205each synchronize data by the respective internal clocks, is performed on the second communication channel. The communication format for asynchronous communication will be described later.

The lens microprocessor111receives from the camera microprocessor205a command requesting transmission of optical data and a command indicating a registration No. for identifying optical data, via the first communication channel. The lens microprocessor11generates the optical data requested by the camera microprocessor205, and stores this optical data in the transmission data buffer333of the second lens communication unit112b, along with the registration No. received from the camera microprocessor205. In a case where the camera microprocessor205has requested multiple sets of optical data, the optical data is sequentially generated and stored in the transmission data buffer333. Once all optical data requested by the camera microprocessor205is stored in the transmission data buffer333, the buffer control unit318causes the transmission data buffer333to output the data to be transmitted, one byte at a time. The transmission parallel/serial converter332converts the optical data that is parallel data into serial data, and also converts into a later-described asynchronous communication format, and outputs to the second lens-camera communication line (DLC2).

The camera microprocessor205converts the optical data that is the received serial data at the reception serial/parallel converter331of the second camera communication unit208binto parallel data, and extracts the body of the optical data from the asynchronous communication format. The buffer control unit313then stores the extracted optical data in the data reception buffer330.

Thus, communication of transmission request commands for optical data from the camera microprocessor205to the lens microprocessor111via the first communication channel, and transmission of optical data from the lens microprocessor111to the camera microprocessor205via the second communication channel, is performed.

Next, the communication formats on the first communication channel and second communication channel will be described with reference toFIGS. 4Athrough4B2.FIG. 4Aillustrates an example of a communication format of the clock synchronous communication performed on the first communication channel. InFIG. 1A, clock signals transmitted/received at the clock communication line (LCLK), and signal waveforms of data signals transmitted/received at the camera-lens communication line (DCL) and data signals transmitted/received at the first lens-camera communication line (DLC), are illustrated in order from above. In the following description, clock signals will be referred to as clock signals LCLK signals, data signals transmitted/received on the camera-lens communication line (DCL) will be referred to as DCL signals, and data signals transmitted/received on the first lens-camera communication line (DLC) will be referred to as DLC signals. The first camera communication unit208aoutputs clock signals LCLK, and also outputs 8-bit data of B7 through B0 as DCL signals, so as to match the leading edge of the clock signals LCLK. The first lens communication unit112adetects the clock signals LCLK, and also outputs 8-bit data of B7 through B0 as DLC signals, so as to match the leading edge of the clock signals LCLK.

The first camera communication unit208areceives the 8-bit B7 through B0 DLC signals, so as to match the leading edge of the clock signals LCLK. The first lens communication unit112areceives the also 8-bit B7 through B0 DCL signals, so as to match the leading edge of the clock signals LCLK. Thus, control is effected so as to perform communication between the first camera communication unit208aand first lens communication unit112aat timings corresponding to clock signals output from the first camera communication unit208avia the clock communication line at the first communication channel. Accordingly, the camera microprocessor205and lens microprocessor111can exchange data over the first communication channel.

Also, the first lens communication unit12athat has received the 8-bit of B7 through B0 DCL signals holds the clock signal LCLK at Low for a predetermined time Tbusy, and releases the Low when the predetermined time Tbusy elapses. The predetermined time Tbusy is time necessary to process the received data at the lens microprocessor111, and the camera microprocessor205does not transmit data to the lens microprocessor111during this time. Communication of multiple bytes between the camera microprocessor205and lens microprocessor111on the first communication channel is performed by repeating communication processing according to this communication format.

FIG.4B1illustrates a communication format example of asynchronous communication performed over the second communication channel. An example is illustrated here where a 1-bit start bit, an 8-bit data bit, and a 1-bit stop bit, making up ten bits form one frame, as the format of data that is communicated. Note that the data bits may be seven bits or 16 bits, and a parity bit may be included. Alternatively, the stop bit may be two bits.

FIG.4B2illustrates a timing synchronization method in the asynchronous communication over the second communication channel. The camera microprocessor205and lens microprocessor111transmit/receive data by operating internal clocks according to a clock frequency, i.e., clock rate, that both have agreed on. For example, the internal clock is set to a clock rate that is 16 times the communication rate between the camera microprocessor205and lens microprocessor111. The start point of data sampling is decided to be sampling at the internal clock of the trailing edge of the start bit in the received data, so that this can be shown as synchronization timing in FIG.4B2. This data at the position of eight clocks starting at this synchronization timing is latched, so that this can be shown as data sampling timing in FIG.4B2. Accordingly, data can be read at the middle of each bit. Performing data sampling in this way for each bit enables data communication to be performed over only the one second lens-camera communication line (DLC2).

The flowchart inFIG. 11illustrates the flow of processing that the camera microprocessor205and lens microprocessor111perform. S inFIG. 11means “step”.

First, the processing that the camera microprocessor205performs will be described. The camera microprocessor205starts processing from a state where the interchangeable lens100has not been mounted to the camera body200, in step S2001. In S2002, the camera microprocessor205determines whether or not the interchangeable lens100has been mounted to the camera body200, and if mounted, the flow advances to S2003.

In S2003, the camera microprocessor205starts supply of power source to the interchangeable lens100. Accordingly, the lens microprocessor111and the actuators in the interchangeable lens100can operate.

Next, in S2004, the camera microprocessor205performs initial communication processing with the lens microprocessor111. This initial communication processing will be described later.

Next, in S2005, the camera microprocessor205performs steady communication processing with the lens microprocessor111. This steady communication processing is processing that is performed when the camera body200is performing steady operations (live view display, etc.), and will be described in detail later.

Next, in S2006, the camera microprocessor205determines whether or not conditions are satisfied for sleep processing. For example, determination is made regarding whether or not an auto power off time that the user has set has elapsed. If the conditions are satisfied, the flow advances to S2007, otherwise, the flow returns to S2005.

In S2007, the camera microprocessor205performs communication (sleep request) to transition the lens microprocessor111to a sleep state, and the camera microprocessor205itself also transitions to a sleep state.

Next, in S2008, the camera microprocessor205that is in a sleep state determines whether or not a sleep state canceling factor has occurred. For example, determination is made regarding whether or not the camera operating unit207has been operated. In a case where a sleep state canceling factor has occurred, the flow returns to S2005and steady communication processing is resumed.

The processing performed at the lens microprocessor111will be described next. The lens microprocessor111starts the flow from a state where the interchangeable lens100is not mounted to the camera body200in S2010. The S2011, the lens microprocessor111determines whether or not power source supply from the camera body200has started. Once power source supply has started, the lens microprocessor111performs later-described initial communication processing in S2012.

Then in S2013, the lens microprocessor111performs the later-described initial communication processing. Further, in S2014, the lens microprocessor111determines whether or not a sleep request has been received from the camera microprocessor205. In a case of having received a sleep request, in S2015the lens microprocessor111performs processing to transition the lens microprocessor111itself to a sleep state. In a case where a sleep request has not been received, the lens microprocessor111returns to S2013.

In S2016, the lens microprocessor111in a sleep state determines whether or not there has been a communication request from the camera microprocessor205, and in a case where there has been a communication request, the sleep state is cancelled, and the lens microprocessor111returns to S2013and resumes steady communication processing.

Next, the flowcharts inFIGS. 5A and 5Bwill be used to describe the initial communication processing performed by the camera microprocessor205and lens microprocessor111in S2004and S2012inFIG. 11. First, the initial communication processing that the camera microprocessor205performs will be described with reference to the flowchart inFIG. 5A. An example of a specific command illustrated inFIG. 12will be used for description here.

The camera microprocessor205that has started up in S501determines in S502whether or not the interchangeable lens100has been mounted to the camera body200, and in a case where the interchangeable lens100has been mounted, advances to S503.

In S503, the camera microprocessor205starts power source supply to the interchangeable lens100. This enables the camera microprocessor205and lens microprocessor111to communicate.

Next, in S504, the camera microprocessor205transmits a communication rate capable information command for the second communication channel (0xAA in hexadecimal) shown inFIG. 12to the lens microprocessor111, to notify that the camera microprocessor205has capabilities to use the second communication channel.

In the following description, assumption will be made that a communication rate 1 through communication rate 8 have been decided between the camera microprocessor205and lens microprocessor111, corresponding to each of bit0through bit7, as the communication rate definitions shown inFIG. 13. Of the communication rate 1 through communication rate 8, communication rate 1 is the slowest communication rate, and communication rate 8 is the fastest communication rate. Definition has been made such that the speed increases from communication rate 1 toward communication rate 8.

In the present embodiment, an assumption will be made that the camera microprocessor205handles communication rates of communication rate 1 through communication rate 5. The camera microprocessor205transmits communication rate information in which bit0, bit1, bit2, bit3, and bit4, corresponding to communication rate 1, communication rate 2, communication rate 3, communication rate 4, and communication rate 5, are enabled, as communication rate information, i.e., 0x1F in hexadecimal following the communication rate capable information notification command (0xAA in hexadecimal). In a case where the camera side cannot use the second communication channel, communication rate information in which bit0through bit7has all been invalidated, i.e., 0x00 in hexadecimal is transmitted to the lens microprocessor111following the communication rate capable information notification command (0xAA in hexadecimal).

In S505, the camera microprocessor205obtains communication rate information that is usable on the second communication channel from the lens microprocessor111. In the present embodiment, assumption will be made that the lens microprocessor111can handle communication rate 1, communication rate 2, and communication rate 3. In this case, the lens microprocessor111transmits to the camera microprocessor205communication rate information in which bit0, bit1, and bit2, corresponding to communication rate 1, communication rate 2, and communication rate are enabled, as communication rate information, i.e., 0x07 in hexadecimal.

Next, in S506, determination is made regarding whether or not the second communication channel can be used. In the present embodiment, the camera microprocessor205determines whether or not the second communication channel can be used from the communication rate information obtained from the lens microprocessor111in S505. Specifically, in a case where no valid bit is included in the communication rate information received from the lens microprocessor111in S505, determination is made that the second communication channel cannot be used. Cases where the second communication channel cannot be used includes cases where the communication rates that the lens microprocessor111can use and the communication rates that the camera microprocessor205can use do not match, and cases where the lens microprocessor111cannot handle the second communication channel. In a case where the second communication channel can be used, the camera microprocessor205advances to S507, and in a case where the second communication channel cannot be used, advances to S511and forbids use of the second communication channel, and ends the initial communication processing in S512.

Thus, determination is made regarding whether or not the second communication channel can be used based on communication rate information in the present embodiment, but other methods may be used if whether or not the second communication channel can be used can be determined. For example, identification information (e.g., information such as an ID or the like) of the interchangeable lens may be obtained when turning the power on or when mounting the interchangeable lens, and whether or not the second communication channel can be used may be determined based on the identification information.

In S507, the camera microprocessor205decides the usage communication rate on the second communication channel from the communication rate information obtained from the lens microprocessor111in S505, and sets that information in the second camera communication unit208b.

Then in S508, the camera microprocessor205transmits the usage communication rate that has been decided in S507to the lens microprocessor111over the camera-lens communication line (DCL) of the first communication channel, in the bit expression shown inFIG. 13. The camera microprocessor205at this time decides the communication rate 3, which is the fastest communication rate that both the camera microprocessor205and the lens microprocessor111can use, to be the usage communication rate. The camera microprocessor205then transmits a usage communication rate communication command for the second communication channel (0xCC), and 0x04 representing communication rate 3, to the lens microprocessor111.

In S509, the camera microprocessor205then performs data registration processing for registering a definition of optical data (hereinafter referred to as “optical data definition”, described later in detail) to be transmitted to the lens microprocessor111over the second communication channel. The camera microprocessor205transmits a data registration request command to the lens microprocessor111in the data registration processing, thereby causing the lens microprocessor111to also perform data registration processing, which will be described in detail later.

Then in S510, the camera microprocessor205determines whether or not data registration processing has been successful in S509, and if successful, advances to S512and completes the initial communication processing at the camera microprocessor205. Note that in a case where determination has been made in S506that the second communication channel cannot be used, and in a case where determination has been made in S510that data registration processing has failed, the camera microprocessor205forbids usage of the second communication channel in S511, and completes the initial communication processing in S512.

Next, the initial communication processing performed at the lens microprocessor111in response to the initial communication processing of the camera microprocessor205described above will be described with reference to the flowchart inFIG. 5B.

In S521, the lens microprocessor111that has started the initial communication processing awaits supply of power source from the camera microprocessor205in S522.

In S523, the lens microprocessor111receives the communication rate capable information command transmitted from the camera microprocessor205(0xAA) and the communication rate information (0x1F) of the communication rates that the camera can use.

In S524, the lens microprocessor111determines whether or not the second communication channel can be used, based on the communication rate information obtained from the camera microprocessor205in S523and the communication rate information that the lens microprocessor111can use on the second communication channel. If the second communication channel can be used, the lens microprocessor111advances to S525, and if not usable (the lens microprocessor111cannot handle the functions of the second communication channel), advances to S528. Note that determination of whether or not the second communication channel can be used may be made using identification information of the camera, for example, in the same way as in the description of S506.

In S525, the lens microprocessor111transmits information of communication rates that can be used on the second communication channel to the camera microprocessor205. The lens microprocessor111here transmits information in which bit0, bit1, and bit2, corresponding to communication rate 1, communication rate 2, and communication rate 3 are enabled, as communication rate information (0x07), to the camera microprocessor205, as described in S505.

In S526, the lens microprocessor111receives the communication rate information of the second communication channel transmitted by the camera microprocessor205in S508, and sets this to the second lens communication unit112b.

Further, in S527, the lens microprocessor111performs data registration processing for registering optical data definitions to be transmitted to the camera microprocessor205, in response to receiving a data registration request command from the camera microprocessor205as described in S509. Details of this data registration processing will be described later. Thereafter, the lens microprocessor111advances to S529, and ends the initial communication processing.

On the other hand, in S528, the lens microprocessor111performs processing for a case where the second communication channel is not usable (cannot handle the second communication channel). Specifically, the lens microprocessor111clears all bits indicating communication rates that can be used on the second communication channel, shown inFIG. 13, and transmits 0x00 to the camera microprocessor205as a communication rate capable information obtaining command shown inFIG. 12. Thereafter, the lens microprocessor111advances to S529and ends the initial communication processing.

Next, data registration processing that the camera microprocessor205and lens microprocessor111perform in S509and S527respectively will be described with reference to the flowcharts inFIGS. 5C and 5D.

First, the data registration processing that the camera microprocessor205performs will be described with reference to the flowchart inFIG. 5C. In S541, the camera microprocessor205determines whether or not this is the first time of performing data registration processing for the lens microprocessor111of the interchangeable lens100that is mounted. In a case where this is the first time to perform data registration processing for the lens microprocessor111, the camera microprocessor205advances to S542, and if data registration processing has already been performed, advances to S545.

In S542, the camera microprocessor205makes inquiry to the lens microprocessor S11regarding the number of optical data definitions that can be registered, via the first communication channel. In S543, the camera microprocessor205obtains the number that can be registered, as a reply from the lens microprocessor111.

Next, in S544, the camera microprocessor205sets a registration index to “1”. On the other hand, in S545, the registration index is set to “number already registered+1”.

Next, in S546, the camera microprocessor205determines whether or not the number set in the registration index exceeds the number that can be registered, obtained in S543. In a case where the number set in the registration index exceeds the number that can be registered, the camera microprocessor205advances to S550where data registration processing is determined to have failed, and ends the data registration processing. In a case where the number set in the registration index does not exceed the number that can be registered, the camera microprocessor205advances to S547.

In S547, the camera microprocessor205creates an optical data definition indicating the type and transmission order of optical data that is to be transmitted from the lens microprocessor111over the second communication channel. Specifically, an optical data definition is created by correlating a registration No. of the optical data definition, the type of optical data, and the transmission order, as illustrated inFIG. 14. Information that has been registered in order for optical data to be transmitted from the lens microprocessor111is also referred to as “registration information”, with type and transmission order of optical data being examples of registration information.

For example, correlated with registration No. 1 are optical data “focal length information (2)”, “aperture diameter information (3)”, “focus position information (2)”, “zoom position information (2)”, “gyro information (20)”, and “focus correction information (100)”, in this transmission order. Correlated with registration No. 2 are “focus position information (2)” and “focus correction information (100)”, in this transmission order. Correlated with registration No. 3 are “focal length information (2)”, “aperture diameter information (3)”, “zoom position information (2)”, and “current aperture position information (3)”, in this transmission order. Correlated with registration No. 4 are “gyro information (20)” and “tripod fixation determination information (1)”, in this transmission order. Note that the values in the parentheses for each kind of information indicate the data length (bytes) for expressing the information thereof. Note that these optical data definitions are examples, and may include other optical data (information).

In a case where the combination of optical data correlated differs between one registration No. and another registration No., for example, part of the correlated optical data may overlap. Also, there may be cases where the combinations of correlated optical data are the same, but the order of correlation differs, for example. That is to say, it is sufficient for at least one of the combination of correlated optical data and the order to differ between one registration No. and another registration No.

In S548, the camera microprocessor205transmits an optical data definition created in S547, along with the data registration request command, to the lens microprocessor111via the first communication channel. The communication processing at this time will be described with reference toFIG. 6.

FIG. 6illustrates signal waveforms of a clock signal line (LCLK)601, camera-lens communication line (DCL)602, and first lens-camera communication line (DLC)603, making up the first communication channel. A case of registering N optical data definitions is illustrated here, showing registration processing604of a first optical data definition (No. 1), registration processing605of a second optical data definition (No. 2), and registration processing606of an N'th optical data definition (No. 3).

In the registration processing604, the camera microprocessor205transmits a data registration request command (0xDD inFIG. 12)610to the lens microprocessor111. Next, the camera microprocessor205transmits an entry No. 611 indicating the registration No. to be registered, to the lens microprocessor111. An entry No. command “1” corresponding to the registration No. 1 is transmitted here. The camera microprocessor205then transmits a count command612indicating the number of optical data definitions that should be registered, “0x0A in a case where the number is ten, as shown inFIG. 12, for example, to the lens microprocessor111. The camera microprocessor205then transmits the optical data to be included in the optical data definitions to the lens microprocessor111as first registration command (613) through n'th registration command (614), and finally transmits a checksum615to the lens microprocessor111to guarantee the data.

Upon receiving the data registration request command from the camera microprocessor205, the lens microprocessor111transmits a response “00” to the camera microprocessor205. Further, each time the aforementioned command is received, the lens microprocessor111transmits responses “Ack”616and617to the camera microprocessor205, for confirmation of the reception. Finally, the lens microprocessor111receives the checksum615from the camera microprocessor205, and thus transmits a response for confirmation thereof to the camera microprocessor205. The registration processing described above is performed for all optical data definitions (No. 1 through No. N).

The camera microprocessor205that has performed the data registration request processing in S548by the above-described processing advances to S549and determines the data registration processing to have been successful, and ends this processing.

Next, the data registration processing performed by the lens microprocessor111will be described with reference to the flowchart inFIG. 5D. In S561, the lens microprocessor111determines whether or not this is the first time to perform data registration processing with the camera microprocessor205, and advances to S562if the first time, and to S565if data registration processing has already been performed.

In S562, the lens microprocessor111receives an inquiry from the camera microprocessor205, regarding the number of optical data definitions that can be registered. The lens microprocessor111responds the number that can be registered to the camera microprocessor205in S563. At this time, the lens microprocessor111decides the number that can be registered in accordance with the capacity of the storage area storing optical data, such as RAM or the like within the interchangeable lens100.

Next, in S564, the lens microprocessor111sets the registration index for finalizing an address in the storage region to “1”. On the other hand, in S565, the registration index is set to “number already registered+1”.

Next, in S566, the lens microprocessor111receives the data registration request command that the camera microprocessor205has transmitted in S548.

Next, in S567, the lens microprocessor111stores the optical data corresponding to registration commands 1 through n transmitted from the camera microprocessor205, to addresses in the storage region offset in accordance with the registration index, with the head address as a reference. This processing ends the data registration processing for the lens microprocessor111.

Next, communication processing performed when the camera microprocessor205and lens microprocessor111communicate over the second communication channel will be described.FIG. 7illustrates signal waveforms of a clock signal line (LCLK)701, camera-lens communication line (DCL)702, and first lens-camera communication channel (DLC)703, making up the first communication channel. Also illustrated is the signal waveforms on the second lens-camera communication line (DLC2)704making up the second communication channel.

A case will be described here regarding performing communication over the second communication channel at an imaging start timing700for live view images or shooting moving images. Note however, that communication may be made over the second communication channel in cases of performing imaging other than live view images or shooting moving images.

The camera microprocessor205is triggered by the imaging start timing700, and performs second communication channel request processing705over the first communication channel, to request the lens microprocessor111for communication over the second communication channel. The camera microprocessor205transmits a second communication channel communication request command (0xE0 inFIG. 12)706, requesting communication over the second communication channel, to the lens microprocessor111in this second communication channel request processing705. Subsequently, the camera microprocessor205transmits a registration No. command (e.g., 0x01 indicating registration No. 1)707indicating the registration No. of the optical data definition corresponding to the optical data regarding which transmission over the second communication channel is to be requested, and a LimitTiming command708, to the lens microprocessor111. The registration No. command707is equivalent to a data specification command and registration specification command. The LimitTiming command708is equivalent to a limit time command.

The LimitTiming command708is time that the camera microprocessor205specifies, and indicates a limit time by which the lens microprocessor111should perform transmission of optical data over the second communication channel. The lens microprocessor111must perform transmission of optical data to the camera microprocessor205within the limit time LimitTiming specified in the LimitTiming command708, starting from the time of having received the second communication channel communication request command706. For example, in a case where the LimitTiming command708is 0x64 such as illustrated inFIG. 12, the lens microprocessor111performs communication over the second communication channel before the limit time of 100 ms elapses after having received the second communication channel communication request command706. Note that an arrangement may be made where, in a case of 0 ms being specified in the LimitTiming command, no limit time is set for execution of communication over the second communication channel.

Upon having received the second communication channel communication request command706, registration No. command707, and LimitTiming command708, the lens microprocessor111transmits “00”, “ACK1”, and “ACK2” to the camera microprocessor205as responses thereto.

The lens microprocessor111that has received the registration No. command707performs communication processing over the second communication channel before the limit time LimitTiming elapses. Specifically, the lens microprocessor111transmits optical data709correlated with a registration No. to the camera microprocessor205in the registered transmission order, along with a response (registration No.) confirming the registration No. indicated in the registration No. command707. Transmitting optical data including the response for confirming the registration No. (e.g., the same No. as the registration No. shown in the registration No. command707) enables the camera microprocessor205to confirm that the optical data specified in the registration No. command707is being received.

Next, communication processing performed by each of the camera microprocessor205and lens microprocessor111in the communication shown inFIG. 7will be described with reference to the flowcharts inFIGS. 8A and 8B. First, the communication processing that the camera microprocessor205performs will be described with reference toFIG. 8A.

The camera microprocessor205starts communication processing for control (control communication) in S801. Next, in S802, the camera microprocessor205detects a start timing interruption of imaging control, ant is an internal signal thereof. Note that a case is exemplified here where communication control is started with the start timing interruption for imaging control as a trigger, but a start timing interruption of other control may be used as a trigger.

Next, in S803, the camera microprocessor205determines whether or not this is the first time to perform communication using the second communication channel, and whether or not settings of the camera body200(camera settings) have been changed. In a case of performing communication using the second communication channel for the first time, in S804the camera microprocessor205selects an optical data definition (i.e., registration No.) corresponding to the optical data regarding which the lens microprocessor111is to be requested to transmit, out of the multiple registered optical data definitions shown inFIG. 14.

Also, in a case where the camera settings have been changed, the registration No. corresponding to the optical data regarding which the lens microprocessor111is to be requested to transmit, is re-selected. For example, in a case where the imaging cycle (framerate) of the camera body200has been changed, there will be an increase or decrease in the time over which communication processing can be performed over the second communication channel depending on this framerate, so there are cases where it is better to change the optical data to be communicated over the second communication channel. Another reason is that, in a case where AF processing, automatic exposure (AE) processing, and image stabilization processing settings have been changed, as camera settings, there is a possibility that the content of the optical data that should be obtained over the second communication channel will change.

Next, in S805, the camera microprocessor205transmits the second communication channel communication request command706, registration No. command707, and LimitTiming command708, shown inFIG. 7, to the lens microprocessor111via the first communication channel.

Next, in S806, the camera microprocessor205determines whether or not the limit time instructed to the lens microprocessor111in the LimitTiming command708has elapsed. In a case where the limit time has elapsed, the camera microprocessor205advances to S810, and in a case where reception of the optical data from the lens microprocessor111via the second communication channel has been confirmed in S807before the limit time elapses, advances to S808. Judgement of reception of the optical data is performed by having detected the start bit serving as reception data in the communication waveforms illustrated in FIG.4B2, for example.

In S808, the camera microprocessor205confirms whether or not the registration No. included in the optical data709, shown inFIG. 7, that has been received in S807, matches the registration No. indicated by the registration No. command transmitted to the lens microprocessor111in S805. If the registration No. matches, the camera microprocessor205advances to S809, and if not matching, advances to S811.

In S809, the camera microprocessor205analyzes and holds the optical data transmitted from the lens microprocessor111via the second communication channel in the transmission order in optical data definitions shown inFIG. 14for each registration No. That is to say, in a case where the registration No. is 1, two bytes of data, which are Data[0] and Data[1] are saved as focal length information, and the following three bytes of Data[2], Data[3], and Data[4] are saved as aperture diameter information. Subsequently, data analysis and holding is performed in the same way to off-focus correction information. Thereafter, the camera microprocessor205returns to S802.

In S810, the camera microprocessor205transmits a communication cancellation request command (the 0xE1 shown inFIG. 12) to the lens microprocessor111, to request cancellation of communication over the second communication channel. The flow then advances to S811.

In S811, the camera microprocessor205transmits a communication reset request command requesting resetting of the second communication channel, to the lens microprocessor111via the first communication channel. This is because there is a possibility that there has been a problem in data registration processing as to the second communication channel at the lens microprocessor111, in a case where the limit time has run over in S809or there has been a mismatch in registration Nos. in S808. The reason that the camera microprocessor205requests the lens microprocessor111to reset the second communication channel is as follows. That is to say, the second communication channel is a channel that only transmits data from the lens microprocessor111to the camera microprocessor205, so the lens microprocessor111has no way to confirm communication abnormalities due to noise and the like.

Next, in S812, there is a possibility that there has been a problem in data registration processing requested to the lens microprocessor111, so the camera microprocessor205requests the lens microprocessor111to perform data registration processing at the second communication channel again. The data registration processing is the same processing as the processing in S509, i.e., the same processing as that described inFIG. 5C, so description will be omitted here. The camera microprocessor205then returns to S802.

Next, the communication processing that the lens microprocessor111performs will be described with reference toFIG. 8B. In S821, the lens microprocessor111starts control communication. Then in S822, the lens microprocessor111receives the second communication channel communication request command706, registration No. command707, and LimitTiming command708, transmitted by the camera microprocessor205in S805. In a case where the registration No. command707received at this time indicates a registration No. that is unregistered at the lens microprocessor111, the probability that the registration No. command707is not being exchanged correctly, due to communication disturbance such as noise or the like, is high. Accordingly, the lens microprocessor111responds with a communication abnormality to the camera microprocessor205.

Upon confirming the response of a communication abnormality state from the lens microprocessor111, the camera microprocessor205communicates a communication logic reset request command for the second communication channel (0x99 in hexadecimal) shown inFIG. 12. Upon receiving the communication logic reset request command, the lens microprocessor111initializes (resets) the communication logic circuit of the second communication channel.

Next, in S823, the lens microprocessor111generates optical data to be transmitted, in accordance with the type of optical data and the transmission order corresponding to the registration No. received in S822.

Next, in S824, the lens microprocessor111determines whether or not a communication reset request command transmitted from the camera microprocessor205has been received via the first communication channel. The lens microprocessor111that has received the communication reset request command resets the second communication channel within the lens microprocessor111in S825, and returns to S822.

The lens microprocessor111also determines in S826whether or not a communication channel request command transmitted from the camera microprocessor205has been received. The lens microprocessor111that has received the communication channel request command cancels communication over the second communication channel and returns to S822. If no communication channel request command has been received, the lens microprocessor111advances to S827, and transmits the optical data generated in S823to the camera microprocessor205via the second communication channel, and returns to S822.

As described above, in the present embodiment, transmission of commands such as control commands with a high priority level (real-time properties) from the camera microprocessor205to the lens microprocessor111, and transmission of notifications such as responses as to the commands from the lens microprocessor111, are performed over the first communication channel. The optical data from the interchangeable lens100that the camera microprocessor205needs is received via the second communication channel that is different from the first communication channel. At this time, the first camera communication unit208ain the camera microprocessor205can transmit the commands to the lens microprocessor111regardless of whether the second camera communication unit208bis receiving optical data. In other words, the first lens communication unit112aof the lens microprocessor111can receive the commands from the camera microprocessor205regardless of whether the second lens communication unit112bis transmitting optical data. Accordingly, even in cases where great amounts of optical data are to be received at the camera microprocessor205from the lens microprocessor111, delay of operations corresponding to control commands, such as zooming, light amount adjustment, focusing, and image stabilization, and so forth at the interchangeable lens100, can be reduced.

Second Embodiment

In the method described in the first embodiment, where optical data is communicated from the lens microprocessor111to the camera microprocessor205via the second communication channel, the camera microprocessor205can only specify a registration No. corresponding to one optical data definition per one second communication channel communication request processing. There are cases where handling is difficult with this method in cases where the control cycles of various operations differ at the camera body200. For example, a case is where AF processing for controlling focusing operations uses the imaging cycle as a control cycle, but AE processing for controlling light amount adjustment operations uses P times worth the imaging cycle as the control cycle.

In this case, the optical data communication for AF processing and the optical data communication for AE processing are separated, with the second communication channel being used differently in accordance with the control cycles of each. Accordingly, communication processing where multiple registration Nos. can be specified for one second communication channel communication request processing will be described in the present embodiment. Note that the configuration of the camera body200and interchangeable lens100in the present embodiment is the same as the configuration of the first embodiment illustrated inFIGS. 1 through 6.

First, communication processing performed when the camera microprocessor205and lens microprocessor111communicate over the second communication channel will be described with reference toFIG. 9.FIG. 9illustrates signal waveforms of a clock signal line (LCLK)701, camera-lens communication line (DCL)702, and first lens-camera communication line (DLC)703, making up the first communication channel. Also illustrated are the signal waveforms on the second lens-camera communication line (DLC2)704making up the second communication channel. Here, a case where optical data communication for AF processing and optical data communication for AE processing are performed at the second communication channel will be described, using an example of specific commands shown inFIG. 15.

The camera microprocessor205is triggered by the imaging start timing700, and performs second communication request processing901over the first communication channel, to request the lens microprocessor111for communication of optical data over the second communication channel. The camera microprocessor205transmits a second channel multiple communication request command (0xE2 inFIG. 15)902, requesting communication of optical data corresponding to multiple optical data definitions over the second communication channel, to the lens microprocessor111in this second channel communication request processing901.

Next, the camera microprocessor205transmits, to the lens microprocessor111, a registration count command903notifying the number of registration Nos. of multiple optical data definitions corresponding to the optical data regarding which transmission is to be requested (0x02 corresponding to the number two, in this case). Further, a registration No. command904specifying the first of the multiple registration Nos. (0x02 corresponding to registration No. 2 in this case) is transmitted to the lens microprocessor111. The registration No. 2 is a registration No. of an optical data definition including focus position information, focus correction information, and so forth, that is necessary for AF processing, for example. The camera microprocessor205then transmits a LimitTiming1 command (e.g., 0x64 indicating 100 ms)905to the lens microprocessor111, to instructing a limit time for transmitting the optical data corresponding to the first registration No. The lens microprocessor111must transmit optical data corresponding to the first registration No. to the camera microprocessor205within this limit time LimitTiming1, starting from the time of having received the second channel multiple communication request command902.

The camera microprocessor205then transmits a registration No. command906specifying the second of the multiple registration Nos. (0x03 corresponding to registration No. 3 here) to the lens microprocessor111. Registration No. 3 is a registration No. of an optical data definition including focus length information, current aperture position information, and so forth, that is necessary for AE processing, for example. The camera microprocessor205then transmits a LimitTiming2 command (e.g., 0xC8 indicating 200 ms)907to the lens microprocessor111, to instructing a limit time for transmitting the optical data corresponding to the second registration No. The lens microprocessor111must start transmission of optical data corresponding to the second registration No. to the camera microprocessor205within this limit time LimitTiming2, starting from the time of having received the second channel multiple communication request command902.

The lens microprocessor111that has received the second channel multiple communication request command902, registration count command903, registration No. commands904and906, and LimitTiming1 and LimitTiming2 commands905and907, transmits “00”, and “ACK1” through “ACK3” to the camera microprocessor205as responses thereto.

The lens microprocessor111that has received the first registration No. command904performs communication processing over the second communication channel before the limit time LimitTiming1 elapses. Specifically, the lens microprocessor111transmits optical data910correlated with a registration No. to the camera microprocessor205in the registered transmission order, along with a response (registration No.) confirming the registration No. indicated in the first registration No. command904that was received.

Further, the lens microprocessor111that has received the second registration No. command906starts communication processing over the second communication channel before the limit time LimitTiming2 elapses. Specifically, the lens microprocessor111transmits optical data912correlated with a registration No. to the camera microprocessor205in the registered transmission order, along with a response (registration No.) confirming the registration No. indicated in the second registration No. command906that was received.

Note thatFIG. 9illustrates a case where, when communication over the second communication channel corresponding to the first registration No. command904is completed, the camera microprocessor205performs second channel communication request processing920again, at imaging start timing700′. In the second channel communication request processing920, the camera microprocessor205transmits a second channel communication request command (e.g., 0xE0)921, a registration No. command (e.g., 0x02)922, and a LimitTiming command (e.g., 0x64)923, to the lens microprocessor111. A case of requesting transmission again of the optical data corresponding to the registration No. command (0x02)904in the earlier second channel communication request processing901is illustrated here. The lens microprocessor111must transmit the optical within the limit time LimitTiming, starting from the time of having received the second channel communication request command921.

The lens microprocessor111that has received the second channel communication request command921, registration No. command922, and LimitTiming command923, transmits “00”, “ACK1”, and “ACK2” to the camera microprocessor205as responses thereto.

A communication blank time is provided between the transmission of optical data corresponding to the registration No. command906and the transmission of optical data corresponding to the registration No. command921on the second communication channel inFIG. 9. This communication blank time will be described later.

A first absolute limit time is decided when the lens microprocessor111receives the second channel multiple communication request command902, and is derived from the limit time LimitTiming1 for communicating optical data corresponding to the registration No. command904over the second communication channel. A second absolute limit time is decided when the lens microprocessor111receives the second channel multiple communication request command902, and is derived from the limit time LimitTiming2 for communicating optical data corresponding to the registration No. command906over the second communication channel. A third absolute limit time is decided when the lens microprocessor111receives the second channel communication request command921, and is derived from the limit time LimitTiming for communicating optical data corresponding to the registration No. command922over the second communication channel. In the present embodiment, the lens microprocessor111decides which optical data corresponding to which registration No. to transmit to the camera microprocessor205with priority, using these absolute limit times1through3. This priority determination processing will be described later.

Next, the communication processing that the camera microprocessor205and lens microprocessor111each perform in the communication illustrated inFIG. 9will be described with the flowchart inFIGS. 10aand10B. Steps inFIGS. 10aand10B that are the same as steps shown inFIGS. 8A and 8Bwill be denoted by the same step numbers, and description will be omitted.

First, communication processing that the camera microprocessor205performs will be described with reference toFIG. 10A. The camera microprocessor205passes through S801and S802and advances to S803. In a case where communication processing is being performed for the first time in S803, or the camera settings have been changed, the camera microprocessor205selects multiple optical data definitions (registration Nos.) corresponding to the optical data regarding which the lens microprocessor111is to be requested to transmit, from the multiple registered optical data definitions in S1003.

Next, in S1004, the camera microprocessor205transmits the second channel multiple communication request command902, registration count command903, registration No. command904, and LimitTiming1 command905, to the lens microprocessor111via the first communication channel. The camera microprocessor205further transmits the registration No. command906and LimitTiming2 command907to the lens microprocessor111via the first communication channel. Thereafter, the camera microprocessor205advances to S1005.

On the other hand, in a case where the communication processing is the second time in S803, the camera microprocessor205advances to S1001. In S1001, the camera microprocessor205re-selects the registration No. corresponding to the optical data of which reception from the lens microprocessor111has already been completed (registration No. 2 inFIG. 9). Specifically, in a case where the registration Nos. indicated by the registration No. commands904and906transmitted to the lens microprocessor111are a registration No. for AF processing of which the control cycle is short, and a registration No. for AE processing of which the control cycle is long, the registration No. for AF processing is re-selected. The reason is that the communication processing on the second communication channel for AF processing of which the control cycle is short is completed quicker than the communication processing on the second communication channel for AE processing of which the control cycle is long, so a registration No. command indicating a registration No. for AF processing is transmitted to the lens microprocessor111each time.

Next, in S1002, the camera microprocessor205transmits the second channel communication request command921, registration No. command922indicating the registration No. re-selected in S1001, and LimitTiming command923to the lens microprocessor111using the first communication channel. At this time, in a case where multiple registration Nos. are re-selected, a second channel multiple communication request command is transmitted to the lens microprocessor111instated of a second channel communication request command. Thereafter, the camera microprocessor205advances to S1005.

In S1005, the camera microprocessor205determines whether limit time LimitTiming1 or LimitTiming2 has elapsed. In a case where a limit time has elapsed, the camera microprocessor205advances to S1006, and in a case where reception of the optical data from the lens microprocessor111via the second communication channel has been confirmed in S1007before the limit time elapses, advances to S1008. Judgement of reception of the optical data is performed by having detected the start bit serving as reception data in the communication waveforms illustrated in FIG.4B2, for example.

In S1006, the camera microprocessor205transmits a communication cancellation request command (0xE1 inFIG. 12) to the lens microprocessor111, to request cancellation of communication on the second communication channel. The flow then advances to S811.

In S1008, in a case of having transmitted a registration No. command indicating multiple registration Nos. to the lens microprocessor111in S1004or S1002, the camera microprocessor205determines whether or not a registration No. corresponding to the multiple registration Nos. is included in the optical data received in S1007. In a case where the camera microprocessor205receives optical data from the lens microprocessor111in S1007, a registration No. corresponding to that optical data is received as well. Accordingly, even in a case of having transmitted registration No. commands indicating multiple registration Nos. to the lens microprocessor111in S1002or S1004, which registration No. command a response is being made to can be determined. In a case where a registration No. corresponding to the optical data received in S1007is included in the multiple registration Nos., the camera microprocessor205advances to S809, receives optical data from the lens microprocessor111in the same way as in the first embodiment, and returns to S802. On the other hand, if no registration No. corresponding to the received optical data is included, there is a possibility of a communication abnormality, so the camera microprocessor205passes through S811and S812and returns to S802.

Next, communication processing that the lens microprocessor111performs will be described with reference toFIG. 10B. In S1010after S821, the lens microprocessor111receives the second channel multiple communication request command, registration No. command, and so forth, that the camera microprocessor205has transmitted in S1004or S1002, via the first communication channel.

Next, in S1011, the lens microprocessor111performs priority determination processing for setting the order of priority for generating optical data, with regard to the multiple registration No. commands received in S1010. Specifically, the lens microprocessor111compares the absolute limit time derived from the limit time LimitTiming set for the multiple registration Nos. Priority is given to generation of optical data corresponding to the registration No. of which the absolute limit time is earlier.

This will be described with reference toFIG. 9. The lens microprocessor111derives a first absolute limit time at which the limit time LimitTiming1 set with regard to the registration No. (904) elapses from the time of having received the second channel multiple communication request command902that the camera microprocessor205has transmitted in S1003. In the same way, the lens microprocessor111derives a second absolute limit time at which the limit time LimitTiming2 set with regard to the registration No. (906) elapses from the time of having received the second channel multiple communication request command902that the camera microprocessor205has transmitted in S1003. The first absolute limit time is earlier than the second absolute limit time, so the lens microprocessor111generates with priority the optical data corresponding to the registration No. (904) to which the first absolute limit time has been set.

More specifically, optical data corresponding to the registration No. (904) to which the first absolute limit time has been set is generated. After ending generation of the optical data corresponding to the registration No. (904) to which the first absolute limit time has been set, optical data corresponding to the registration No. (906) to which the second absolute limit time has been set is generated.

In the other hand, the lens microprocessor111that has received the second channel communication request command921from the camera microprocessor205in S1002derives a third absolute limit time at which the limit time LimitTiming3 set with regard to the registration No. (922) elapses from the time of that reception. The second absolute limit time is earlier than the third absolute limit time, so the lens microprocessor111generates with priority the optical data corresponding to the registration No. (906) to which the second absolute limit time has been set.

Next, the lens microprocessor111determines whether or not a communication reset request command has been received from the camera microprocessor205in S824, and if not received, advances to S1012. In a case of having received a communication reset request command, the lens microprocessor111passes through S825and returns to S1010.

In S1012, the lens microprocessor111determines whether or not a communication cancellation request command has been received from the camera microprocessor205. If a communication cancellation request command has been received, the lens microprocessor111advances to S1013, and if not, to S1014.

In S1013, the lens microprocessor111cancels generation of optical data corresponding to the registration No. that is the object of cancellation. That is to say, in a case where the communication cancellation request command received in S1012is a command to cancel all communication requests on the second communication channel (0xE3) shown inFIG. 15, the lens microprocessor111stop all communication on the second communication channel. In a case where the communication cancellation request command is the command (0xE1) shown inFIG. 12, generation of optical data corresponding to the registration No. specified by the subsequently-received registration No. command (e.g., 0x01) is cancelled. Thereafter, the lens microprocessor111returns to S1010.

In S1014, the lens microprocessor111provides a communication blank time (predetermined time) starting at the timing of having transmitted optical data to the camera microprocessor205via the second communication channel in a later-described S1015. This communication blank time is time necessary for the camera microprocessor205to analyze and read in optical data stored in the data reception buffer330in S809when communication is performed from the lens microprocessor111to the camera microprocessor205in S1015.

The communication blank time may be decided between the camera microprocessor205and lens microprocessor111beforehand, or may be notified from the camera microprocessor205to the lens microprocessor111in step S504described in the first embodiment.

In S1015, the lens microprocessor111transmits optical data, corresponding to the registration No. that is determined to be of the highest priority in S1011, to the camera microprocessor205, over the second communication channel. Thereafter, the lens microprocessor111returns to S1010.

According to the present embodiment as well, even in cases where great amounts of optical data are to be received at the camera microprocessor205from the lens microprocessor111, delay of operations corresponding to control commands, such as zooming, light amount adjustment, focusing, and image stabilization, and so forth at the interchangeable lens100, can be reduced, in the same way as with the first embodiment. Further, in the present embodiment, in a case where there are multiple sets of optical data (registration Nos.) for the camera microprocessor205to receive from the lens microprocessor111, transmission of optical data can be individually requested in accordance with control cycles and usage priority level at the camera body200.

Accordingly, usage of communication bandwidth between the camera microprocessor205and lens microprocessor111can be optimized.

It should be noted that the above-described embodiments are only representative examples, and that various modifications and alterations may be made to the embodiments when carrying out the present invention.

OTHER EMBODIMENTS

Regarding the first communication channel, communication by three-line clock synchronous communication is shown in the first embodiment and the second embodiment. As explained earlier, three-line asynchronous communication can be applied to the first embodiment and the second embodiment instead of the three-line clock synchronous communication. Shown inFIG. 16is waveforms of signals transmitted and received between the camera microprocessor205and lens microprocessor111by the three-line asynchronous communication. A request-to-send (RTS) communication line (RTS) serves as a first communication line when asynchronous communication (using three lines) is performed. The RTS communication line is a communication line that supplies transmission request signals serving as timing signals for obtaining data from the camera microprocessor205that is the communication master for the lens microprocessor111.

The transmission request channel, for example, is used for providing notices such as transmission requests (transmission instructions) for the lens data, and switch requests (switch instructions) for communication processes described later, from the camera microcomputer205to the lens microcomputer111. The provision of the transmission request is performed by switching a signal level (voltage level) on the transmission request channel between High as a first level and Low as a second level. A transmission request signal provided to the transmission request channel is hereinafter referred to as “request-to-send signal RTS”. The request-to-send signal RTS is provided from the camera microcomputer205serving as a communication master to the lens microcomputer111serving as a communication slave.

When the request-to-send signal RTS is received, the lens microcomputer111sets the signal level to Low in one bit time period in order to provide a notice of a start of one frame transmission of the lens data signal DLC to the camera microcomputer205. The one bit time period indicating a start of one frame is called “start bit ST” in this embodiment. That is, one data frame starts from this start bit ST. The start bit ST is provided as a head bit of each one frame of the lens data signal DLC. Next, the lens microcomputer111transmits one-byte lens data in an 8-bit time period, from a subsequent second bit to a ninth bit. The data bits are arranged in a most significant bit (MSB)-first format starting from a highest-order data bit D7 and continuing to data bits D6, D5, D4, D3, D2 and D1 in this order, and ending with a lowest-order data bit D0. The lens microcomputer111then adds one bit parity information (parity bit) PA at a tenth bit and sets the signal level of the lens data signal DLC to High in a time period of a stop bit SP indicating an end of the one frame. Thus, the data frame starting from the start bit SP ends.

As explained above, when the three-line asynchronous communication is performed at first communication channel, the communication via the second communication line and the third communication line is performed at corresponding timing with the request-to-send signal RTS transmitted via the RTS communication line. In other words, the camera microprocessor205serves as a communication master to control timing of the communication performed at the first communication channel.

On the other hand, the lens microprocessor111serves as a communication master to control timing of the communication performed at the second communication channel, and communication can be performed at a timing not dependent on the timing of communication by the first communication channel. More specifically, communication by the second lens-camera communication line can be performed at a timing regardless of timings corresponding to clock signals transmitted from the camera microprocessor205to the lens microprocessor111via the clock communication line.

This application claims the benefit of Japanese Patent Application Nos. 2017-108204 filed on May 31, 2017 and 2018-095847, filed on May 18, 2018 which are hereby incorporated by reference herein in their entirety.