Accessory device, camera, communication control method, medium, and camera system

Abstract

The present invention provides an accessory device, a camera, a communication control method, a medium, and a camera system. A camera (200) and an accessory device (100, 300) communicate via a channel including a data communication channel for data communication and a notification channel for notifying the timing of communication via the data communication channel. Upon receiving communication partner designation data via the data communication channel using communication in a first communication mode, each of the accessory devices (100, 300) switches from the first communication mode to the second communication mode, the communication partner designation data indicating that the relevant accessory device has been selected as the communication partner with the camera (200).

Description

[0001] (This application is a divisional application of an application filed on May 30, 2018, with application number 201880035925.6 and invention title “Accessory device, camera, communication control program and camera system”.) Technical Field

[0002] The present invention relates to an accessory device, a camera, a communication control program and a camera system. Background Art

[0003] As an example of an interchangeable lens camera system, there is known a system in which a camera performs image pickup processing and lens control, and an interchangeable lens serving as a first accessory device performs lens driving in accordance with a control command from a camera main unit. In such a camera system, transmission of a control command from the camera main unit to the interchangeable lens and transmission of lens information from the interchangeable lens to the camera main unit are performed via a communication channel for mutual exchange of information.

[0004] There is also known a camera system in which an intermediate adapter serving as a second accessory device (e.g., a converter for changing the focal length of an interchangeable lens) can be connected between a camera main unit and an interchangeable lens to expand a photographing function. In such a camera system, in addition to communication between the camera main unit and the interchangeable lens, communication between the camera main unit and the intermediate adapter is often required. In this case, the camera main unit specifies a communication partner from among a plurality of accessory devices and communicates with the specified communication partner.

[0005] Patent Document 1 discloses a communication control method according to an I2C (Inter-Integrated Circuit) communication protocol. In I2C communication, a plurality of communication slaves are connected to a communication master, and communication is performed between the communication master and a communication slave designated by the communication master.

[0006] In I2C communication, the communication master sends address information specifying a specific slave to all communication slaves. Each communication slave retains the specific address information assigned to itself, and the communication slave that retains the specific address information corresponding to the address information sent from the communication master becomes the communication partner of the communication master.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-148592 Summary of the invention

[0010] Problem that the invention aims to solve

[0011] In the communication system according to the I2C communication protocol disclosed in Patent Document 1, each time communication is performed between a communication master device and a communication slave device, address information specifying the communication slave device needs to be sent and received. In addition, the communication slave device is required to confirm whether it is selected as the communication partner with the communication master device based on the address information.

[0012] In the above communication method, it is necessary to include address information in the data format, and the amount of data that can be transmitted is reduced corresponding to the data of the address information. In addition, since the communication slave device confirms whether it is selected as the communication partner for each communication, there is a possibility that a waiting time may be generated until the communication starts. Therefore, the communication method disclosed in Patent Document 1 is accompanied by the possibility that the data communication speed between the communication master device and the communication slave device cannot be sufficiently improved.

[0013] An object of the present invention is to realize an accessory device and a camera that enable high-speed communication between the camera and the accessory device.

[0014] Solutions for solving problems

[0015] The present invention provides an accessory device that can be mounted on a camera, the accessory device including an accessory control unit for controlling communication between the camera and the accessory device via a channel, the channel including a data communication channel for data communication and a notification channel for notifying the timing of communication via the data communication channel, wherein the accessory control unit is capable of switching between a first communication mode and a second communication mode, the first communication mode being used for communication between the camera and a plurality of accessory devices mounted on the camera and including the accessory device, and the second communication mode being used for communicating with the camera alone, and the second communication mode being different from the first communication mode in terms of a voltage level of the notification channel during a time period of receiving data from the camera, and the accessory control unit switches from the first communication mode to the second communication mode when receiving communication partner designation data via the data communication channel in the first communication mode, the communication partner designation data indicating that the accessory device has been selected as a communication partner with the camera in the second communication mode.

[0016] The present invention also provides a camera capable of mounting a first accessory device and a second accessory device, the camera including a camera control unit for controlling communication via a channel including a data communication channel for data communication with the first accessory device and the second accessory device, and a notification channel for notifying timing of communication via the data communication channel, wherein the camera control unit is capable of switching a first communication mode and a second communication mode, the first communication mode being used for communication with the first accessory device and the second accessory device, and the second communication mode being used for communication with only one of the first accessory device and the second accessory device, and the second communication mode being different from the first communication mode in terms of a voltage level of the notification channel during a time period in which data is sent from the camera, and the camera control unit switches from the first communication mode to the second communication mode when transmitting communication partner designation data to the first accessory device and the second accessory device via the data communication channel in the first communication mode, the communication partner designation data indicating a communication partner with the camera in the second communication mode.

[0017] Effects of the Invention

[0018] According to the present invention, an accessory device and a camera are obtained which enable high-speed communication between the camera and the accessory device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a block diagram showing the structure of a camera system including a camera and an accessory device.

[0020] Figure 2 is a schematic diagram showing a communication circuit in a camera system.

[0021] Figure 3 Shows the format of the data sent and received.

[0022] Figure 4 is a schematic diagram showing communication waves in broadcast communication.

[0023] Figure 5 is a schematic diagram showing communication waves in P2P communication.

[0024] Figure 6 Schematic diagram showing communication waves when the communication mode is switched.

[0025] Figure 7 This is a flowchart referred to in order to explain the communication flow in broadcast communication.

[0026] Figure 8This is a flowchart referred to in order to explain the communication flow in P2P communication.

[0027] Fig. 9 is a schematic diagram showing communication waves in broadcast communication.

[0028] Fig.10 This is an explanatory diagram for reference in order to explain other communication channels. DETAILED DESCRIPTION

[0029] Hereinafter, a communication control method in an accessory device including an interchangeable lens and an intermediate adapter and a camera according to the present invention will be described in detail with reference to the accompanying drawings. Between the accessory device and the camera, communication is performed according to a plurality of communication modes. The term "communication mode" means a broadcast communication mode and a P2P communication mode. In the following description, the broadcast communication mode is referred to as a first communication mode and the P2P communication mode is referred to as a second communication mode in some cases.

[0030] The present invention relates to a camera system including a method of changing the communication mode between a camera main unit and an accessory device as required. Figure 1 The camera system shown has an intermediate adapter 300 installed between the camera 200 and the interchangeable lens 100. Although the following embodiment is described in conjunction with an example in which one intermediate adapter 300 is installed between the camera 200 and the interchangeable lens 100, a plurality of intermediate adapters may be installed between the camera 200 and the interchangeable lens 100.

[0031] According to the present invention, in broadcast communication, data is transmitted from the camera 200 operating as a communication master to each accessory device operating as a communication slave. When the camera 200 performs P2P communication, which is one-to-one communication with a specific accessory device, information indicating the communication partner with the camera 200 in the P2P communication is notified to each accessory device in the broadcast communication.

[0032] Since the communication partner with the camera 200 has been notified to each accessory device at the timing of starting the P2P communication, the camera 200 does not need to send information for specifying the communication partner to each accessory device in the P2P communication. Therefore, by switching to the P2P communication which is a one-to-one communication method between the camera 200 and the selected communication partner after selecting the communication partner with the camera 200 in the broadcast communication, the communication speed in the P2P communication can be improved.

[0033] <Description of Configuration of Camera System>

[0034] Figure 1The structure of an image pickup system including a camera 200 according to the present invention, an intermediate adapter 300, and an interchangeable lens 100 is shown, wherein the latter two are accessory devices attachable to the camera 200. Not only a case where an accessory device is directly connected to the camera 200 but also a case where an accessory device is connected to the camera 200 in a state where the intermediate adapter 300 is inserted between the accessory device and the camera 200 are described as representing a state where the accessory device is attached to the camera 200.

[0035] The camera 200 , the interchangeable lens 100 , and the intermediate adapter 300 transmit control commands and internal information via respective communication units provided inside. Each communication unit is adapted for broadcast communication and P2P communication, and communicates according to a communication mode determined by the camera 200 .

[0036] First, the detailed structures of the interchangeable lens 100, the intermediate adapter 300, and the camera 200 are described. The intermediate adapter 300 and the camera 200 are mechanically and electrically connected via a mount 401 as a coupling mechanism. The intermediate adapter 300 is supplied with power from the camera 200 via a power supply terminal (not shown) provided in the mount 401 to operate an adapter microcomputer (hereinafter referred to as adapter MICOM) 302.

[0037] The interchangeable lens 100 and the intermediate adapter 300 are mechanically and electrically connected via a mount 400 as a coupling mechanism. The interchangeable lens 100 is supplied with power from the camera 200 via a power supply terminal (not shown) provided in the mount 400 and a power supply terminal (not shown) provided in the mount 401. By using the power received from the camera 200, the interchangeable lens 100 operates various actuators and a lens microcomputer (hereinafter referred to as a lens MICOM) 111 described later. In addition, the interchangeable lens 100, the intermediate adapter 300, and the camera 200 are connected via ( Figure 2 The communication terminals shown in the figure communicate with each other.

[0038] Next, the structure of the interchangeable lens 100 is described. The interchangeable lens 100 includes an imaging optical system. The imaging optical system includes a field lens 101, a zoom lens 102 for zooming, an aperture unit 114 for adjusting the amount of light, an image stabilizing lens 103, and a focus lens 104 for focus adjustment, which are arranged in order from the side close to the object OBJ.

[0039] The zoom lens 102 and the focus lens 104 are held by lens holders 105 and 106, respectively. The lens holders 105 and 106 are movably guided in the direction of the optical axis indicated by the dotted line in the figure by guide shafts not shown, and are driven in the direction of the optical axis by stepping motors (M) 107 and 108, respectively. The stepping motors 107 and 108 move the zoom lens 102 and the focus lens 104, respectively, in synchronization with the drive pulse.

[0040] The image stabilization lens 103 is movable in a direction perpendicular to the optical axis of the imaging optical system to reduce image blur or the like attributable to hand shake.

[0041] The lens MICOM 111 is an accessory control unit for controlling the operation of various components in the interchangeable lens 100. The lens MICOM 111 receives a control command transmitted from the camera 200 via the lens communication unit 112 (i.e., the accessory communication unit), and accepts a request for transmitting lens data. In addition, the lens MICOM 111 performs lens control corresponding to the control command, and transmits lens data corresponding to the transmission request to the camera 200 via the lens communication unit 112.

[0042] In addition, the lens MICOM 111 outputs a drive signal to the zoom drive circuit 119 and the focus drive circuit 120 in response to a control command related to zooming and focusing among the control commands, thereby driving the stepping motors 107 and 108. As a result, a zoom process for controlling a zoom operation using the zoom lens 102 and an auto focus process for controlling a focus adjustment operation using the focus lens 104 are performed.

[0043] The aperture unit 114 includes aperture blades 114a and 114b. The states of the aperture blades 114a and 114b are detected by the Hall element 115, and the detected signals are input to the lens MICOM 111 via the amplifier circuit (Amp) 122 and the A / D converter circuit 123. The lens MICOM 111 outputs a drive signal to the aperture drive circuit 121 according to the input signal from the A / D converter circuit 123, thereby driving the aperture actuator (ACT) 113. As a result, the light amount adjustment operation using the aperture unit 114 is controlled.

[0044] Furthermore, the lens MICOM 111 drives the image stabilization actuator (ACT) 126 via the image stabilization drive circuit 125 according to the shake detected by a shake sensor such as a vibration gyro, not shown, arranged in the interchangeable lens 100. As a result, an image stabilization process of controlling the shift operation of the image stabilization lens 103 is performed.

[0045] The structure of the intermediate adapter 300 is now described. In the present embodiment, the intermediate adapter 300 is an extender for extending the focal length of the interchangeable lens 100. The intermediate adapter 300 is not limited to an extender, and may have various functions. For example, a filter for changing the transmittance of light having passed through the interchangeable lens 100 may be incorporated in the intermediate adapter 300. The intermediate adapter 300 may include a plurality of filters having different optical transmittances, and an appropriate filter among these filters can be selected according to a shooting situation or the like.

[0046] The intermediate adapter 300 in the present embodiment includes a zoom lens 301 for extending the focal length of the interchangeable lens 100, and an adapter MICOM 302 (i.e., an accessory control unit) for controlling the operations of various components in the intermediate adapter 300. The adapter MICOM 302 receives a control command transmitted from the camera 200 via an adapter communication unit 303 (i.e., an accessory communication unit), and performs adapter control corresponding to the control command. In addition, the adapter MICOM 302 transmits adapter data corresponding to a transmission request from the camera 200 to the camera 200 via the adapter communication unit 303.

[0047] Next, the configuration of the camera 200 is described. The camera 200 includes an imaging element 201 such as a CCD sensor or a CMOS sensor, an A / D converter circuit 202, a signal processing circuit 203, a recording unit 204, a camera microcomputer (hereinafter referred to as a camera MICOM) 205, and a display unit 206.

[0048] The imaging element 201 performs photoelectric conversion on a subject image formed by the imaging optical system in the interchangeable lens 100, and outputs an electrical signal (analog signal). The A / D converter circuit 202 converts the analog signal from the imaging element 201 into a digital signal. The signal processing circuit 203 performs various types of image processing on the digital signal from the A / D converter circuit 202, and generates a video signal.

[0049] In addition, the signal processing circuit 203 generates focus information indicating the contrast state of the subject image (i.e., the focus state of the imaging optical system) and brightness information indicating the exposure state from the video signal. The signal processing circuit 203 outputs the video signal to the display unit 206, and the display unit 206 displays the video signal as a live view image for confirming the composition, the focus state, etc.

[0050] The camera MICOM 205 serving as a camera control unit controls the camera 200 in response to inputs from camera operating members such as an imaging instruction switch and various setting switches (not shown). Furthermore, the camera MICOM 205 transmits a control command related to a zoom operation of the zoom lens 102 to the lens MICOM 111 via the camera communication unit 208 in response to an operation of a zoom switch not shown. In addition, the camera MICOM 205 transmits a control command for a light amount adjustment operation of the aperture unit 114 according to brightness information and a focus adjustment operation of the focus lens 104 according to focus information to the lens MICOM 111 via the camera communication unit 208.

[0051] The camera MICOM 205 transmits data to the intermediate adapter 300 and the interchangeable lens 100 together in broadcast communication, and performs one-to-one data communication with one of the intermediate adapter 300 and the interchangeable lens 100 in P2P communication.

[0052] <Description of Configuration of Communication Circuit>

[0053] The following will refer to Figure 2 The following will describe a communication circuit configured in a camera system including the camera 200, the intermediate adapter 300, and the interchangeable lens 100. The camera system in this embodiment includes a notification channel CS for notification of communication timing and a data communication channel DATA for data communication.

[0054] As reference Figure 1 As described above, the camera 200 and the intermediate adapter 300 are connected via a mount 401. The mount 401 includes at least two communication terminals. The intermediate adapter 300 and the interchangeable lens 100 are connected via the mount 400. The mount 400 includes at least two communication terminals. The notification channel CS and the data communication channel DATA are formed by the communication terminals provided in these mounts.

[0055] The notification channel CS is connected to the camera MICOM 205, the adapter MICOM 302, and the lens MICOM 111. Each MICOM can detect the signal level (voltage level) of the notification channel CS. In addition, the notification channel CS is pull-up connected to a power source not shown arranged in the camera 200. The notification channel CS is connectable to the ground via the ground switch 2081 included in the camera 200, and is also connectable to the ground via the ground switch 3031 included in the intermediate adapter 300. In addition, the notification channel CS is connectable to the ground via the ground switch 1121 included in the interchangeable lens 100.

[0056] With the above-described circuit configuration, the signal level of the notification channel CS can be set to Low (first level) by bringing any one of the ground switches included in the camera 200, the intermediate adapter 300, and the interchangeable lens 100 into a connected state (first setting). The signal level of the notification channel CS can be set to High (second level) by bringing all the ground switches included in the camera 200, the intermediate adapter 300, and the interchangeable lens 100 into a disconnected state (second setting).

[0057] Each MICOM can change the connection state between the notification channel CS and the ground by changing the connection state of the ground switch. In other words, each MICOM can set the signal level of the notification channel CS to high or low by changing the connection state of the ground switch.

[0058] For example, the camera MICOM 205 can set the signal level of the notification channel CS to low by bringing the ground switch 2081 included in the camera 200 into the connection state. In the present invention, bringing the ground switch into the connection state is represented by the wording "outputting low to the notification channel CS". In addition, bringing the ground switch into the disconnection state is represented by the wording "outputting high to the notification channel CS".

[0059] Therefore, when all MICOMs output high to the notification channel CS, the signal level of the notification channel CS is set to high. On the other hand, when any MICOM outputs low to the notification channel CS, the signal level of the notification channel CS is set to low. The role of the notification channel CS during data communication will be described later.

[0060] The data communication channel DATA is a bidirectional data communication channel capable of changing the direction of data propagation. The data notification channel DATA is connected to the camera MICOM 205 , the adapter MICOM 302 , and the lens MICOM 111 .

[0061] The data communication channel DATA is connected to the camera MICOM 205 via the input / output conversion switch 2082 included in the camera 200. The camera MICOM 205 includes a data output unit for sending data and a data input unit for receiving data. According to the operation of the input / output conversion switch 2082, the camera MICOM 205 can selectively connect the data communication channel DATA to one of the data output unit and the data input unit.

[0062] In addition, the data communication channel DATA is connected to the adapter MICOM 302 via the input / output conversion switch 3032 included in the intermediate adapter 300. The adapter MICOM 302 includes a data output unit for sending data and a data input unit for receiving data. According to the operation of the input / output conversion switch 3032, the adapter MICOM 302 can selectively connect the data communication channel DATA to one of the data output unit and the data input unit.

[0063] The data communication channel DATA is connected to the lens MICOM 111 via the input / output conversion switch 1122 included in the interchangeable lens 100. The lens MICOM 111 includes a data output unit for sending data and a data input unit for receiving data. According to the operation of the input / output conversion switch 1122, the lens MICOM 111 can selectively connect the data communication channel DATA to one of the data output unit and the data input unit. With the above-mentioned circuit structure, the data propagation direction in the data communication channel DATA can be appropriately switched.

[0064] <Description of data format>

[0065] The following will refer to Figure 3 The format of data communicated via the data communication channel DATA will be described.

[0066] Figure 3 The data format in the start-stop synchronous communication method in which the communication speed is set in advance on both the data transmission side and the data reception side, and data communication is performed at a communication bit rate corresponding to the setting. The term "communication bit rate" means the amount of data that can be transmitted per second, and is expressed in bps (bits per second). Figure 3 The signal waveform of one frame which is the minimum communication unit is shown.

[0067] In a state where data communication is not performed, the signal level of the data communication channel DATA is maintained at a high level. Then, the signal level of the data communication channel DATA is set to low in a 1-bit period to notify the data receiving side of the start of data transmission. This 1-bit period is called a start bit ST, and the data frame starts with the start bit ST. 1 byte of data is transmitted in an 8-bit period from the second bit after the start bit ST to the ninth bit.

[0068] The data bit array adopts the MSB (most significant bit) first format, which starts with the most significant data D7, followed by data D6, data D5, etc., and ends with the least significant data D0. 1 bit of parity information (PA) is added at the tenth bit, and the signal level of the data communication channel DATA is set to high during the time period of the stop bit SP indicating the end of 1 frame. The data frame time period starting with the start bit ST ends. Parity information does not always need to be 1 bit, and multiple bits of parity information can be added. Parity information is not necessary, and a format without parity information added can also be used.

[0069] Alternatively, the data bit array may adopt an LSB (least significant bit) first format, which starts with the least significant data D0, followed by data D1, data D2, etc., and ends with the most significant data D7. Although 1 byte of data is transmitted in an 8-bit time period in the present embodiment, 1 byte of data may be transmitted in a bit time period other than the 8-bit time period.

[0070] <Explanation of Broadcast Communication>

[0071] The following will refer to Figure 4 Broadcast communication is performed under a condition where the camera 200 operates as a communication master and the intermediate adapter 300 and the interchangeable lens 100 each operate as a communication slave.

[0072] Figure 4 The camera MICOM 205 of the camera 200 (ie, the communication master) notifies the lens MICOM 111 and the adapter MICOM 302 (ie, the communication slave) of the start of the broadcast communication by outputting Low to the notification channel CS.

[0073] Then, the camera MICOM 205 transmits the data to the lens MICOM 111 and the adapter MICOM 302 via the data communication channel DATA.

[0074] On the other hand, the lens MICOM 111 and the adapter MICOM 302 output low to the notification channel CS in response to detecting the above-mentioned start bit ST via the data communication channel DATA. Since the camera MICOM 205 has already output low when the lens MICOM 111 and the adapter MICOM 302 output low to the notification channel CS, the signal level of the notification channel CS continues to remain low.

[0075] The lens MICOM 111 and the adapter MICOM 302 notify a communication standby request by outputting a low to the notification channel CS. The communication standby request temporarily stops the communication in the camera system, and the presence or absence of the communication standby request is determined based on the signal level of the notification channel CS.

[0076] After all data has been sent, the camera MICOM 205 outputs high to the notification channel CS. After receiving the stop bit SP sent via the data communication channel DATA, the lens MICOM 111 and the adapter MICOM 302 perform analysis of the received data and internal processing corresponding to the received data. Then, after the preparation for performing the next communication is completed, the lens MICOM 111 and the adapter MICOM 302 output high to the notification channel CS.

[0077] When all components constituting the camera system output high to the notification channel CS, the signal level of the notification channel CS becomes high. The camera MICOM 205, the lens MICOM 111, and the adapter MICOM 302 can confirm the fact that the components constituting the camera system have entered a state capable of performing the next communication based on the signal level of the notification channel CS returning to high.

[0078] exist Figure 4 In the embodiment, the data transmitted from the camera MICOM 205 includes a transmission request command to the adapter MICOM 302, and the data transmission of the adapter MICOM 302 is performed after the data transmission of the camera MICOM 205.

[0079] More specifically, after the signal level of the notification channel CS becomes high, the adapter MICOM 302 outputs low to the notification channel CS. Thus, the adapter MICOM 302 notifies the start of broadcast communication to the lens MICOM 111 and the camera MICOM 205. Then, the adapter MICOM 302 transmits data to the lens MICOM 111 and the camera MICOM 205 via the data communication channel DATA.

[0080] On the other hand, the lens MICOM 111 and the camera MICOM 205 output low to the notification channel CS in response to detecting the above-mentioned start bit ST via the data communication channel DATA. Since the adapter MICOM 302 has already output low to the notification channel CS when the lens MICOM 111 and the camera MICOM 205 output low to the notification channel CS, the signal level of the notification channel CS continues to remain low.

[0081] After all the data has been sent, the adapter MICOM 302 outputs high to the notification channel CS. After receiving the stop bit SP sent via the data communication channel DATA, the lens MICOM 111 and the camera MICOM 205 perform analysis of the received data and internal processing corresponding to the received data. Then, after the preparation for the next communication is completed, the lens MICOM 111 and the camera MICOM 205 output high to the notification channel CS.

[0082] When all the components constituting the camera system output high to the notification channel CS, the signal level of the notification channel CS becomes high. Based on the fact that the signal level of the notification channel CS returns to high, the camera MICOM 205, the lens MICOM 111, and the adapter MICOM 302 can confirm that the components constituting the camera system have entered a state capable of performing the next communication.

[0083] As described above, in broadcast communication, the data sending side notifies the start of broadcast communication to the data receiving side by outputting low to the notification channel CS and changing the signal level of the notification channel CS from high to low. The data receiving side cancels the communication waiting request by changing the output to the notification channel CS from low to high for each component of the camera system.

[0084] Although Figure 4 illustrates an example of the communication wave in the broadcast communication of the present invention, the present invention is not limited to the illustrated example. In another example, the data transmitted or received in one broadcast communication may be multi-byte data instead of 1-byte data.

[0085] In the case of changing the communication mode from broadcast communication to P2P communication, the camera MICOM 205 only sends the data indicating the switching of the communication mode to the lens MICOM 111 and the adapter MICOM 302.

[0086] <Explanation of P2P communication>

[0087] The following will refer to Figure 5 to explain P2P communication (i.e., the second communication mode in the present invention). In P2P communication, the camera 200 operates as a communication master device and performs one-to-one individual communication with the components selected as communication slave devices among the components constituting the camera system.

[0088] Figure 5 Illustrates the signal wave transmitted in P2P communication. Figure 5An example is shown in which the interchangeable lens 100 is selected as a communication slave device. Information indicating a communication slave device in P2P communication is transmitted in broadcast communication. In P2P communication, the data transmission side does not output low to the notification channel CS, and transmits data to the data reception side while keeping the notification channel CS high. Thus, the voltage level of the notification channel CS during data transmission from the camera 200 to the interchangeable lens 100 and the intermediate adapter 300 is made different between broadcast communication and P2P communication.

[0089] When the communication mode is switched from broadcast communication to P2P communication, data transmission from the camera MICOM 205 (ie, the communication master) is started first.

[0090] Figure 5 An example is shown in which, after 1-byte data is transmitted from the camera MICOM 205 to the lens MICOM 111 , 2-byte data is transmitted from the lens MICOM 111 to the camera MICOM 205 .

[0091] After the switching from broadcast communication to P2P communication in the components constituting the camera system has been completed, the camera MICOM 205 (i.e., the communication master) transmits data to the lens MICOM 111 via the data communication channel DATA. After the data transmission is completed, the camera MICOM 205 notifies the communication waiting request by outputting low as the signal level of the notification channel CS. Then, after the preparation for receiving data as the data receiving side is completed, the camera MICOM 205 returns the signal level of the notification channel CS to high.

[0092] On the other hand, the lens MICOM 111 recognizes that data transmission from the camera MICOM 205 is completed according to the change in the signal level of the notification channel CS to low, and performs analysis of the received data and internal processing corresponding to the received data. Figure 5 In the example of , a data transmission request from the lens MICOM 111 to the camera MICOM 205 is included in the data received from the camera MICOM 205 , and the lens MICOM 111 generates data to be transmitted to the camera MICOM 205 .

[0093] Thereafter, the lens MICOM 111 recognizes the cancellation of the communication standby request according to the signal level of the notification channel CS returning to High, and transmits 2-byte data to the camera MICOM 205 .

[0094] After the data transmission is completed, the lens MICOM 111 outputs low as the signal level of the notification channel CS and notifies the communication waiting request. Then, after the preparation for receiving data as the data receiving side is completed, the lens MICOM 111 returns the signal level of the notification channel CS to high. The adapter MICOM 302 that is not selected as the communication partner in the P2P communication neither changes the output to the notification channel CS nor participates in the transmission and reception of data.

[0095] The lens MICOM 111 determines whether to continue P2P communication or to switch to broadcast communication according to the timing of data transmission from the camera MICOM 205 after the signal level of the notification channel CS returns to high. In the case where the lens MICOM 111 receives data from the camera MICOM 205 while the signal level of the notification channel CS remains high, the lens MICOM 111 determines to continue P2P communication. On the other hand, in the case where the lens MICOM 111 receives data from the camera MICOM 205 after the signal level of the notification channel CS changes to low, the lens MICOM 111 determines that the communication mode has been switched from P2P communication to broadcast communication.

[0096] As described above, in P2P communication, the data sending side notifies the data receiving side of the end of data transmission from the data sending side by changing the signal level of the notification channel CS from high to low. Therefore, in P2P communication, multiple data frames can be continuously sent until the data sending side changes the signal level of the notification channel CS. Due to this system configuration in which the communication from the communication master device is not inserted every time the communication slave device sends a data frame, communication between the camera MICOM 205 and each accessory device such as the lens MICOM 111 or the adapter MICOM 302 can be performed at high speed. The data sending side notifies the communication waiting request by keeping the signal level of the notification channel CS at low until the preparation for receiving data as the data receiving side is completed.

[0097] <Description of Switching Communication Mode>

[0098] The following will refer to Figure 6 The following describes an overview of communication performed when broadcast communication and P2P communication are switched. In any of the broadcast communication and the P2P communication, the camera 200 operates as a communication master and performs communication with the intermediate adapter 300 and the interchangeable lens 100. Information indicating a communication partner with the camera main unit in the P2P communication is notified in the broadcast communication.

[0099] Figure 6The communication waves in the communication performed when the broadcast communication and the P2P communication are switched are shown. First, information indicating that the adapter MICOM 302 has been selected as the communication partner in the P2P communication is transmitted and received in the broadcast communication. Then, the P2P communication is performed between the camera MICOM 205 and the adapter MICOM 302. Hereinafter, the information indicating the communication partner in the P2P communication is referred to as the communication partner designation data.

[0100] An example of giving communication partner designation data as a function of a command for switching from broadcast communication to P2P communication will be described below. Instead of using communication partner designation data, switching to P2P communication may be performed by transmitting and receiving a signal instructing switching from broadcast communication to P2P communication.

[0101] After receiving the communication partner designation data, the lens MICOM 111 that is not selected as the communication partner in the P2P communication outputs High to the notification channel CS when the analysis and internal processing of the data received from the camera MICOM 205 are completed. Then, during the period of time in which the P2P communication is performed between the camera MICOM 205 and the adapter MICOM 302, the lens MICOM 111 does not change the output to the notification channel CS, and maintains the setting corresponding to the broadcast communication.

[0102] In more detail, when the switching to P2P communication is completed, the adapter MICOM 302 notifies the camera MICOM 205 of the completion of the switching to P2P communication by outputting a high to the notification channel CS. The camera MICOM 205 also outputs a high to the notification channel CS when the switching to P2P communication is completed. As described above, the lens MICOM 111 that is not selected as the communication partner in the P2P communication outputs a high to the notification channel CS when the analysis and internal processing of the data received from the camera MICOM 205 are completed.

[0103] When detecting that the signal level of the notification channel CS changes to high, the camera MICOM 205 starts Figure 5 The overview of the communication performed in the P2P communication mode is as described above. Figure 5 As described above, the detailed description of P2P communication is omitted here.

[0104] When the P2P communication between the camera MICOM 205 and the adapter MICOM 302 is completed, the camera MICOM 205 transmits communication partner designation data indicating that the lens MICOM 111 has been selected as the communication partner in the P2P communication in broadcast communication. Thereafter, P2P communication is performed between the camera MICOM 205 and the lens MICOM 111.

[0105] Judging from the fact that the signal level of the notification channel CS has changed to Low before data is transmitted from the camera MICOM 205, the adapter MICOM 302 recognizes the fact that switching from the P2P communication to the broadcast communication has been performed.

[0106] <Description of Communication Flow in Broadcast Communication>

[0107] The following will refer to Figure 7 The communication flow in broadcast communication is described below. The camera MICOM 205 and the adapter MICOM 302 execute according to the communication control program which is a computer program. Figure 7 The communication control is shown in the flowchart. Figure 7 In the example, “S” stands for step. Figure 7 The communication flow in the camera MICOM 205 as the communication master and the communication flow in the adapter MICOM 302 as the communication slave are disclosed. The communication flow in the lens MICOM 111 is basically the same as that of the adapter MICOM 302, so the communication flow in the lens MICOM 111 is not disclosed here.

[0108] The camera MICOM 205 determines in S100 whether an event for starting broadcast communication has occurred. If an event for starting broadcast communication has occurred, the camera MICOM 205 proceeds to S101. If the event has not occurred, the determination of S100 is repeated.

[0109] In S101, the start of broadcast communication is notified to the lens MICOM 111 and the adapter MICOM 302 by outputting low to the notification channel CS and setting the signal level of the notification channel CS to low. Then, in S102, the input / output changeover switch 2082 is operated to connect the data communication channel DATA to the data output unit of the camera MICOM 205. In S103, data transmission is started.

[0110] In S104, it is determined whether the data transmitted from the camera MICOM 205 in S103 includes a transmission request command. The transmission request command is a command requesting the communication slave device that has received the data transmitted from the camera MICOM 205 (ie, the communication master device) to transmit data to the camera MICOM 205.

[0111] If the data transmitted from the camera MICOM 205 in S103 does not include a transmission request command, the process proceeds to S105. In S105, after the data transmission from the camera MICOM 205 is completed, the output of low to the notification channel CS is canceled. Then, the process proceeds to S116.

[0112] If the transmission request command is included in the data transmitted from the camera MICOM 205 in S103, the process proceeds to S106. In S106, after the data transmission from the camera MICOM 205 is completed, the data communication channel DATA is connected to the data input unit of the camera MICOM 205. Then, the process proceeds to S107. In S107, the output of low to the notification channel CS is canceled, and high is output.

[0113] In S108, it is determined whether the signal level of the notification channel CS becomes high. This determination is performed continuously until the signal level of the notification channel CS becomes high. When the signal level of the notification channel CS is high, this indicates that the camera system is in a state where communication is possible. If the signal level of the notification channel CS becomes high, it is determined in S109 whether the signal level of the notification channel CS changes to low. This determination is performed continuously until the signal level of the notification channel CS changes to low.

[0114] In response to the signal level of the notification channel CS being changed to low, communication is started from the adapter MICOM 302 (i.e., the communication slave device) to the camera MICOM 205. After determining that the signal level of the notification channel CS is changed to low, the camera MICOM 205 allows reception of data via the data communication channel DATA in S110. Then, the camera MICOM 205 determines in S111 whether a start bit included in the data sent from the adapter MICOM 302 is received. This determination is continuously performed until the start bit is received.

[0115] When the start bit is received, the process proceeds to S112, where a low is output to the notification channel CS. Then, in S113, it is determined whether a stop bit is received. This determination is continued until the stop bit is received. When the stop bit is received, in S114, the reception of data via the data communication channel DATA is prohibited, and analysis of the received data and internal processing corresponding to the received data are performed. Then, in S115, the low output to the notification channel CS is canceled, and a high output is output.

[0116] Then, in S116, it is determined whether the signal level of the notification channel CS becomes high. This determination is continued until the signal level of the notification channel CS becomes high. If the signal level of the notification channel CS becomes high, it is determined in S117 whether the data sent in S103 is the communication partner specified data. If the sent data is the communication partner specified data, the process proceeds to S118 to convert to P2P communication. If the sent data is not the communication partner specified data, the broadcast communication is continued.

[0117] The communication flow in the adapter MICOM 302 will be described below. In S200, it is judged whether the signal level of the notification channel CS changes to low. This judgment is continuously made until the signal level of the notification channel CS changes to low. Since data transmission from the camera MICOM 205 (i.e., the communication master device) starts in response to the signal level of the notification channel CS changing to low, the adapter MICOM 302 allows the reception of data via the data communication channel DATA in S201.

[0118] Then, in S202, it is judged whether a start bit is received. If the start bit is not received, the process proceeds to S203, where in this S203, it is judged whether the signal level of the notification channel CS is high.

[0119] The reason for performing the processes of S203 and S204 here is to make the camera system applicable to the case where P2P communication is carried out between the camera MICOM 205 and the lens MICOM 111 and only the adapter MICOM 302 performs broadcast communication. Since the adapter MICOM 302 does not receive data from the camera MICOM 205 in this case, the adapter MICOM 302 prohibits the reception of data via the data communication channel DATA.

[0120] As described in the above <P2P communication> section, in P2P communication, the signal level of the notification channel CS also changes between high and low. The signal level of the notification channel CS is high in the normal state. In broadcast communication, when a communication wait request is notified or when the start of communication is notified, the signal level of the notification channel CS is set to low. In P2P communication, when a communication wait request is notified, the signal level of the notification channel CS is set to low.

[0121] Assume that the case where the adapter MICOM 302 does not receive a start bit from the camera MICOM 205 is any of the following two cases.

[0122] The first case is the case where data transmission does not start after the camera MICOM 205 sets the signal level of the notification channel CS to low. The second case is the case where the camera MICOM 205 and the lens MICOM 111 are performing P2P communication and the adapter MICOM 302 does not participate in the P2P communication.

[0123] In the first case, since the signal level of the notification channel CS does not become high, the process returns from S203 to S202, and the judgments of S202 and S203 are repeated until data transmission from the camera MICOM 205 starts.

[0124] In the second case, unless any one of the camera MICOM 205 and the lens MICOM 111 notifies the communication waiting request, the signal level of the notification channel CS remains high. In this case, the process basically enters S204 from S203, and the reception of data via the data communication channel DATA is prohibited. In the case where the communication waiting request is notified in the P2P communication, the process returns from S203 to S202, and the judgment of S203 is performed again. Although the judgment of S203 is performed multiple times, in the case where the communication waiting request is canceled and the signal level of the notification channel CS becomes high, the process enters S204 from S203.

[0125] By adding the control flow of S203 and S204 as described above, broadcast communication and P2P communication can be performed in a combined manner in the camera system. Thus, in this embodiment, P2P communication can be performed between the camera MICOM 205 and the lens MICOM 111, while the adapter MICOM 302 can remain in a standby state suitable for broadcast communication.

[0126] Returning to the description of S202, upon receiving the start bit in S202, the adapter MICOM 302 starts analyzing the received data and internal processing corresponding to the received data, and outputs a low to the notification channel CS, thereby notifying the components constituting the camera system of a communication wait request.

[0127] Then, it is determined in S206 whether a stop bit is received. This determination is performed continuously until a stop bit is received. When a stop bit is received, in S207, the reception of data via the data communication channel DATA is prohibited, and the analysis of the received data and the internal processing corresponding to the received data are continued. When the internal processing of the data is completed and a state in which the next data communication can be performed is established, in S208, the output of low to the notification channel CS is canceled, and the output is high.

[0128] In S209, it is determined whether the data received from the camera MICOM 205 includes a transmission request command. If the transmission request command is included, the process proceeds to S210, in which it is determined whether the signal level of the notification channel CS becomes high. This determination is continued until the signal level of the notification channel CS becomes high. When the signal level of the notification channel CS is high, this indicates that the camera system is in a state capable of communication. If the data received from the camera MICOM 205 does not include a transmission request command, the process proceeds to S215 described later.

[0129] If it is determined in S210 that the signal level of the notification channel CS is high, the process proceeds to S211. In S211, a low is output to the notification channel CS to change the signal level of the notification channel CS to low, thereby notifying the camera MICOM 205 and the lens MICOM 111 of the start of the broadcast communication. Then, in S212, the input / output conversion switch 3032 is operated to connect the data communication channel DATA to the data output unit of the adapter MICOM 302. In S213, data transmission is started.

[0130] When the data transmission is completed, in S214, the output of the low to the notification channel CS is canceled, and a high is output. Then, in S215, it is determined whether the signal level of the notification channel CS has become high. This determination is continuously made until the signal level of the notification channel CS becomes high.

[0131] If the signal level of the notification channel CS becomes high, the process proceeds to S216. In S216, the adapter MICOM 302 determines whether the data received from the camera MICOM 205 is the communication partner specified data and whether the adapter MICOM 302 is selected as the communication partner with the camera MICOM 205 in the P2P communication. If the adapter MICOM 302 is selected as the communication partner with the camera MICOM 205 in the P2P communication, the process proceeds to S217, where in this S217, reception of data via the data communication channel DATA is permitted. Then, in S218, the communication mode is changed from the broadcast communication to the P2P communication.

[0132] If the data received from the camera MICOM 205 is not the communication partner specified data, or if the adapter MICOM 302 is not selected as the communication partner in the P2P communication, the broadcast communication is continued without changing to the P2P communication.

[0133] <Communication flow in P2P communication>

[0134] The following will refer to Figure 8 to describe the communication flow in the P2P communication. The camera MICOM 205 and the lens MICOM 111 execute the Figure 8 communication control shown in the flowchart according to the communication control program which is a computer program. In Figure 8 , "S" represents a step. Figure 8 The communication flow in the camera MICOM 205 as the communication master device and the communication flow in the lens MICOM 111 as the communication slave device are disclosed. The communication flow in the adapter MICOM 302 is basically the same as that of the lens MICOM 111, and thus the description of the communication flow in the adapter MICOM 302 is not disclosed here.

[0135] The camera MICOM 205 determines in S300 whether an event for starting P2P communication has occurred. If it is determined that an event for starting P2P communication has occurred, the process proceeds to S301. If the event has not occurred, the determination in S300 is repeated.

[0136] In S301, the input / output changeover switch 2082 is operated to connect the data communication channel DATA to the data output unit of the camera MICOM 205. Then, data transmission is started in S302.

[0137] In S303, a low is output to the notification channel CS, thereby changing the signal level of the notification channel CS to low. Thus, the camera MICOM 205 issues a communication waiting request to the lens MICOM 111 as a communication slave. During the period when the signal level of the notification channel CS is low, the lens MICOM 111 does not transmit data to the camera MICOM 205.

[0138] In S304, it is determined whether a transmission request command is included in the data transmitted from the camera MICOM 205 in S302. The transmission request command is a command requesting the communication slave device to transmit data to the camera MICOM 205. If the transmission request command is not included in the data transmitted from the camera MICOM 205 in S302, data is not transmitted from the lens MICOM 111. In this case, the process proceeds from S304 to S305, and it is confirmed whether the lens MICOM 111 notifies a communication waiting request.

[0139] More specifically, the output of low from the camera MICOM 205 to the notification channel CS is canceled in S305, and it is determined in S306 whether the signal level of the notification channel CS is low. As a result, it can be determined whether the lens MICOM 111 sets the signal level of the notification channel CS to low, that is, whether the lens MICOM 111 notifies the communication waiting request.

[0140] Generally, the lens MICOM 111 that receives the data from the camera MICOM 205 notifies the communication waiting request by outputting a low to the notification channel CS for a certain period of time to perform analysis and internal processing of the received data. S306 is executed to recognize the communication waiting request from the lens MICOM 111. After S305, the signal level of the notification channel CS temporarily becomes high in some cases. In this case, the camera MICOM 205 waits for the signal level of the notification channel CS to change to low by making a judgment of S306. After confirming that the signal level of the notification channel CS has changed to low in S306, the process enters S311.

[0141] Now the process returns to S304. If it is determined in S304 that the data transmitted from the camera MICOM 205 in S302 is a transmission request command, the process proceeds to S307.

[0142] In S307, the input / output changeover switch 2082 is operated to connect the data communication channel DATA to the data input unit of the camera MICOM 205. Furthermore, in S308, the output of Low to the notification channel CS is canceled, and High is output.

[0143] In the state where the signal level of the notification channel CS is high, data is received from the lens MICOM 111. Then, in S309, it is determined whether the signal level of the notification channel CS changes to low. In response to the signal level of the notification channel CS changing to low, it is determined that the data transmission from the lens MICOM 111 is completed, and data analysis is performed in S310.

[0144] Then, in S311, it is determined whether the signal level of the notification channel CS becomes high. This determination is continued until the signal level of the notification channel CS becomes high. The state in which the signal level of the notification channel CS is high indicates that the lens MICOM111 (ie, the communication slave device) is in a state capable of data communication.

[0145] If the signal level of the notification channel CS becomes high, the process proceeds to S312, where it is determined whether an event for transitioning to broadcast communication has occurred. If an event for transitioning to broadcast communication has occurred, the process proceeds to S313, where the communication mode is transitioned to broadcast communication. If an event for transitioning to broadcast communication has not occurred, P2P communication continues.

[0146] The following will describe the communication flow in the lens MICOM 111 (i.e., the communication slave device). After performing switching from broadcast communication to P2P communication, the lens MICOM 111 first receives data transmitted from the camera MICOM 205. During the period in which the lens MICOM 111 receives data transmitted from the camera MICOM 205, the signal level of the notification channel CS is kept high.

[0147] Then, in S400, it is determined whether the signal level of the notification channel CS changes to low. In response to the signal level of the notification channel CS changing to low, it is determined that the data transmission from the camera MICOM 205 is completed, and then data analysis is performed in S401.

[0148] Then, in S402, it is determined whether the signal level of the notification channel CS becomes high. This determination is continued until the signal level of the notification channel CS becomes high. The state where the signal level of the notification channel CS is low indicates that the camera MICOM205 is in the state of notifying the communication waiting request.

[0149] If the signal level of the notification channel CS becomes high, it is determined in S403 whether a transmission request command is included in the data received from the camera MICOM 205. If a transmission request command is not included in the data received from the camera MICOM 205, the process proceeds to S404.

[0150] In S404, by changing the signal level of the notification channel CS to low, the camera MICOM 205 is notified of a communication waiting request to perform internal processing and the like for data received from the camera MICOM 205. When the lens MICOM 111 enters a state capable of communication, in S405, the lens MICOM 111 sets the signal level of the notification channel CS to high and cancels the communication waiting request. Thereafter, the process proceeds to S411.

[0151] Now return to S403. If it is determined in S403 that the data received from the camera MICOM 205 includes a transmission request command, the process proceeds to S406. In S406, the input / output conversion switch 1122 is operated to connect the data communication channel DATA to the data output unit of the lens MICOM 111. Then, in S407, data transmission to the camera MICOM 205 is started.

[0152] After the data transmission to the camera MICOM 205 is completed, in S408, a low is output to the notification channel CS, and the signal level of the notification channel CS changes to low. Thus, the lens MICOM 111 issues a communication waiting request to the camera MICOM 205 as the communication master. During the period in which the signal level of the notification channel CS is low, the camera MICOM 205 does not perform data transmission to the lens MICOM 111.

[0153] In S409, the input / output changeover switch 1122 is operated to connect the data communication channel DATA to the data input unit of the lens MICOM 111. Then, in S410, the output of low to the notification channel CS is canceled, and high is output.

[0154] In S411, it is determined whether the signal level of the notification channel CS becomes high. This determination is continued until the signal level of the notification channel CS becomes high. The state where the signal level of the notification channel CS is high indicates that the camera MICOM 205 and the lens MICOM 111 are in a state where communication is possible.

[0155] As described above, the voltage level of the notification channel CS during data transmission from the camera 200 to the interchangeable lens 100 and the intermediate adapter 300 is made different between broadcast communication and P2P communication. With this system, in the case where the camera 200 communicates with a specific accessory device alone, it is not necessary to notify the communication partner again until the communication partner is changed. Thus, communication between the camera 200 and each accessory device including the interchangeable lens 100 and the adapter 300 can be performed at high speed.

[0156] <Modification>

[0157] The following will explain the broadcast communication Figure 4 The communication control method shown is different from the communication control method. Figure 4 In the broadcast communication shown, the camera MICOM 205 notifies each communication slave device of the start of the broadcast communication by outputting Low to the notification channel CS and changing the signal level of the notification channel CS to Low.

[0158] Fig. 9 The illustrated modification shows an example in which the lens MICOM 111 or the adapter MICOM 302 (i.e., the communication slave device) requests the start of broadcast communication to the camera MICOM 205. The communication request to the camera MICOM 205 is performed when the microcomputer included in the accessory device actively restarts the communication with the camera MICOM 205 while the communication from the camera MICOM 205 to the microcomputer included in the accessory device is temporarily stopped.

[0159] For example, in a case where the user operates the operating member 304 arranged in the intermediate adapter 300, the processing in the present modification is performed. The processing can also be performed in a case where the user operates the operating member 130 arranged in the interchangeable lens 100. In the case of resuming communication from a state where communication is temporarily stopped in the camera system, it is basically appropriate for the camera MICOM 205 (i.e., the communication master device) to actively resume communication. Giving the function of resuming communication to the microcomputer included in the accessory device (i.e., the communication slave device) may be accompanied by the possibility of resuming communication at a timing that is not expected by the camera MICOM 205 (i.e., the communication master device). Therefore, it is not desirable to give the communication slave device the function of resuming communication in an unlimited manner.

[0160] In consideration of the above point, in the present modification, a function of resuming communication is given to a microcomputer included in an accessory device (ie, a communication slave) by issuing a communication start request from the microcomputer included in the accessory device to the camera MICOM 205 .

[0161] Fig. 9 1 shows the communication waveform in the broadcast communication performed in this modification. According to the communication control method in this modification, the lens MICOM 111 or the adapter MICOM 302 (i.e., the communication slave device) monitors the occurrence of a communication start event. If a communication start event occurs, a low is output to the notification channel CS, thereby changing the signal level of the notification channel CS to low.

[0162] In response to the signal level of the notification channel CS being changed to low, the camera MICOM 205 outputs low to the notification channel CS and starts broadcast communication. The flow of broadcast communication after outputting low to the notification channel CS is the same as that of reference 1. Figure 4 The process is the same as described above, so the description of the process is omitted here.

[0163] The above-described embodiment can be implemented by additionally using other communication channels in combination with the notification channel CS and the data communication channel DATA.

[0164] The following will refer to Fig.10 An example to illustrate this situation is shown in Fig.10 In, with Figure 1 The same components are denoted by the same reference numerals, and repeated description of the same components is omitted. Fig.10 Not shown Figure 1 Some of the components shown. The notification channel CS and the data communication channel DATA in the above description correspond to communication lines used for communication referred to herein as third communication.

[0165] The lens MICOM 111 controls a communication unit 131 for first communication and a communication unit 132 for second communication in addition to the communication unit 112. The camera MICOM 205 controls a communication unit 209 for first communication and a communication unit 210 for second communication in addition to the communication unit 112.

[0166] First, the first communication is described. The first communication is performed by means of the communication unit 131 and the communication unit 209. The communication unit 131 communicates according to the instruction from the lens MICOM 111, and the communication unit 209 communicates according to the instruction from the camera MICOM 205 via the notification channel CS1, the data communication channel DCL, and the data communication channel DLC. The communication unit 131 and the communication unit 209 set the voltage level of the notification channel CS1, the communication rate (amount of data per unit time) when starting and stopping synchronous communication, and the communication voltage. In addition, the communication unit 131 and the communication unit 209 send and receive data via the data communication channel DCL and the data communication channel DLC when receiving instructions from the lens MICOM 111 and the camera MICOM 205.

[0167] The notification channel CS1 is, for example, a signal line for notifying a communication request from the camera 200 to the interchangeable lens 100. The data communication channel DCL is a channel used when data is transmitted from the camera 200 to the interchangeable lens 100, and the data communication channel DLC is a channel used when data is transmitted from the interchangeable lens 100 to the camera 200.

[0168] In the first communication, the camera MICOM 205 and the lens MICOM 111 communicate according to the clock synchronization communication or the start-stop synchronization communication. The initial communication performed after the interchangeable lens 100 has been connected to the camera 200 is also initially performed according to the first communication. The camera MICOM 205 and the lens MICOM 111 communicate for the identification information of the interchangeable lens 100, and in the case where it is determined that the interchangeable lens 100 attached to the camera 200 is applicable to the start-stop synchronization communication, the communication mode is switched from the clock synchronization communication to the start-stop synchronization communication. Based on the communication result of the identification information, the camera MICOM 205 can determine whether the interchangeable lens 100 is applicable to the third communication in which the adapter 300 is also included. If the camera MICOM 205 determines that the interchangeable lens 100 is applicable to the third communication, the camera MICOM 205 can perform authentication communication for identifying the interchangeable lens 100 and the intermediate adapter 300 via P2P communication.

[0169] Next, the second communication is described. The second communication is a one-way communication from the interchangeable lens 100 to the camera 200. The second communication is performed by means of the communication unit 132 and the communication unit 210. Via the notification channel CS2 and the data communication channel DLC2, the communication unit 132 communicates according to an instruction from the lens MICOM 111, and the communication unit 210 communicates according to an instruction from the camera MICOM 205. The camera communication unit 208 and the lens communication unit 118 transmit and receive data according to clock synchronization communication or start-stop synchronization communication. By using not only the data communication channel DLC for the first communication but also the data communication channel DLC2 for the second communication, a large amount of data can be transmitted from the interchangeable lens 100 to the camera 200 in a short time.

[0170] The above-described embodiment is merely a typical example, and various modifications or changes may be made to the embodiment when the present invention is actually implemented. For example, although the above-described embodiment shows an example of using an interchangeable lens and an intermediate adapter as an accessory device, an interchangeable lens directly mounted to a camera, a flash directly mounted to a camera, etc. may also be used as an accessory device.

[0171] The present invention is not limited to the above-described embodiments, and various changes and modifications may be made without departing from the spirit and scope of the present invention. Therefore, in order to disclose the scope of the present invention, the following claims are attached.

[0172] This application claims the benefit of Japanese Patent Application No. 2017-108267, filed May 31, 2017, and Japanese Patent Application No. 2018-102943, filed May 30, 2018, which are hereby incorporated by reference herein in their entirety.

Claims

1. An accessory device that can be mounted on a camera, the accessory device including an accessory control unit for controlling communication between the camera and the accessory device via a channel including a data communication channel for data communication and a notification channel for notifying timing of communication via the data communication channel, in, The accessory control unit performs the following operations: capable of switching a first communication mode for communication without specifying a communication partner and a second communication mode for communication between the camera and the accessory device specified as a communication partner, and switching from the first communication mode to the second communication mode when receiving communication partner designation data via the data communication channel in the first communication mode, the communication partner designation data indicating that the accessory device has been selected as a communication partner with the camera in the second communication mode, wherein a voltage level of the notification channel when the accessory control unit receives data from the camera is different between the first communication mode and the second communication mode.

2. The accessory device according to claim 1, wherein: A voltage level of the notification channel during a period of receiving data from the camera in the first communication mode is a first level, and a voltage level of the notification channel during a period of receiving data from the camera in the second communication mode is a second level higher than the first level.

3. The accessory device according to claim 2, wherein: The accessory control unit changes a voltage level of the notification channel after receiving data from the camera in the first communication mode, and transmits data to the camera via the data communication channel.

4. The accessory device according to claim 3, wherein: The accessory control unit changes the voltage level of the notification channel from the second level to the first level, and then transmits data to the camera via the data communication channel in a state where the voltage level of the notification channel is at the first level.

5. The accessory device according to claim 2, wherein: The accessory control unit restarts the communication from the camera by changing the voltage level of the notification channel from the second level to the first level in a state where the communication from the camera via the data communication channel is stopped in the first communication mode.

6. The accessory device according to claim 2, wherein: The accessory control unit starts data transmission to the camera in response to a voltage level of the notification channel being changed from the first level to the second level after starting data reception from the camera in the second communication mode.

7. The accessory device according to claim 6, wherein: The accessory control unit starts receiving data from the camera in a state where the voltage level of the notification channel is at the second level, and starts sending data to the camera in response to an event that the voltage level of the notification channel changes from the second level to the first level and further changes to the second level again after the start of data reception.

8. The accessory device of claim 1, wherein: The accessory control unit notifies the end of data transmission from the accessory device by changing the voltage level of the notification channel from the voltage level at the start of data transmission to the camera to a voltage level different from the voltage level at the start of data transmission to the camera in the second communication mode.

9. The accessory device of claim 2, wherein: The accessory control unit changes the voltage level of the notification channel from the second level to the first level after transmitting data to the camera in the second communication mode.

10. The accessory device of claim 8, wherein: The accessory control unit can send a plurality of frames of data to the camera in succession.

11. The accessory device of claim 1, wherein: When the communication partner designation data received from the camera in the first communication mode is data indicating that the accessory device is not selected, the accessory control unit does not switch from the first communication mode to the second communication mode.

12. The accessory device according to any one of claims 1 to 11, wherein: The accessory device and the camera are capable of setting the notification channel to a first setting and a second setting, a voltage level of the notification channel is different between a case where one of the accessory device and the camera sets the notification channel to the first setting and a case where the accessory device and the camera set the notification channel to the second setting, and The accessory control unit performs the following operations: setting the notification channel to the first setting during a period of time in which data is received from the camera in the first communication mode, and The notification channel is set to the second setting during at least a portion of a period of time during which data is received from the camera in the second communication mode.

13. A camera capable of mounting an accessory device, the camera including a camera control unit for controlling communication via channels including a data communication channel for data communication with the accessory device and a notification channel for notifying timing of communication via the data communication channel, in, The camera control unit performs the following operations: capable of switching a first communication mode for communication without specifying a communication partner and a second communication mode for communication between the camera and the accessory device specified as a communication partner, and switching from the first communication mode to the second communication mode when transmitting communication partner designation data to the accessory device via the data communication channel in the first communication mode, the communication partner designation data indicating a communication partner with the camera in the second communication mode, wherein a voltage level of the notification channel when the camera control unit sends data to the accessory device is different between the first communication mode and the second communication mode.

14. The camera according to claim 13, wherein: The camera control unit performs the following operations: when the camera control unit transmits data in the first communication mode, setting the voltage level of the notification channel to a first level, and When the camera control unit transmits data in the second communication mode, the voltage level of the notification channel is set to a second level, the second level being higher than the first level.

15. The camera of claim 14, wherein: In the first communication mode, in a state where communication from the camera via the data communication channel is stopped, data communication to an accessory device mounted to the camera is restarted in response to a voltage level of the notification channel being changed from the second level to the first level.

16. The camera of claim 14, wherein: The camera control unit changes the voltage level of the notification channel from the second level to the first level in response to completion of data transmission in the second communication mode.

17. The camera of claim 14, wherein: The camera and the accessory device are each capable of setting the notification channel to a first setting and a second setting, a voltage level of the notification channel is different between a case where at least one of the camera and the accessory device sets the notification channel to the first setting and a case where the camera and the accessory device set the notification channel to the second setting, and The camera control unit performs the following operations: In response to the end of data transmission in the first communication mode, switching the setting of the notification channel from the first setting to the second setting, and In response to the end of data transmission in the second communication mode, the setting of the notification channel is switched from the second setting to the first setting.

18. A camera according to claim 16 or 17, wherein: The camera control unit can continuously send a plurality of data frames to the accessory device.

19. A non-transitory computer-readable storage medium storing a communication control program used by a computer in an accessory device, the accessory device being mountable to a camera and communicating with the camera via a channel, the channel comprising a data communication channel for data communication and a notification channel for notifying timing of communication via the data communication channel, the accessory device being capable of switching between a first communication mode and a second communication mode, the first communication mode being used for communication without specifying a communication partner, and the second communication mode being used for communication between the camera and the accessory device specified as a communication partner, and a voltage level of the notification channel when the accessory device receives data from the camera being different between the first communication mode and the second communication mode, the communication control program causing the computer to execute the following steps: receiving communication partner designation data from the camera in the first communication mode, the communication partner designation data indicating that the accessory device has been selected as a communication partner with the camera in the second communication mode; and When the communication partner designation data is received, switching from the first communication mode to the second communication mode is performed.

20. A non-transitory computer-readable storage medium storing a communication control program used by a computer in a camera, the camera being capable of mounting an accessory device, the camera performing communication via a channel including a data communication channel for data communication with the accessory device and a notification channel for notifying timing of communication performed via the data communication channel, the camera being capable of switching between a first communication mode and a second communication mode, the first communication mode being used for communication without specifying a communication partner, and the second communication mode being used for communication between the camera and the accessory device specified as a communication partner, and a voltage level of the notification channel when the camera transmits data to the accessory device being different between the first communication mode and the second communication mode, the communication control program causing the computer to execute the following steps: transmitting communication partner designation data to the accessory device in the first communication mode, the communication partner designation data indicating the accessory device selected as the communication partner in the second communication mode; and When the communication partner designation data is transmitted, switching is performed from the first communication mode to the second communication mode.

21. A camera system comprising a camera, a first accessory device and a second accessory device, the first accessory device and the second accessory device being mountable to the camera, in, the camera including a camera control unit for controlling communication via channels including a data communication channel for data communication with the first accessory device and the second accessory device and a notification channel for notifying timing of communication via the data communication channel, The first accessory device and the second accessory device each include an accessory control unit for controlling communication via a channel including the data communication channel and the notification channel, the camera control unit and the accessory control units in the first accessory device and the second accessory device are each capable of switching a first communication mode for communication without specifying a communication partner and a second communication mode for communication between the camera and a communication partner specified from an accessory device mounted on the camera, The camera control unit switches from the first communication mode to the second communication mode when transmitting communication partner designation data in the first communication mode, the communication partner designation data indicating a communication partner with the camera in the second communication mode, and the accessory control unit in the accessory device designated by the communication partner designation data among the first accessory device and the second accessory device switches from the first communication mode to the second communication mode upon receiving the communication partner designation data; and wherein a voltage level of the notification channel when the camera control unit sends data to the accessory device is different between the first communication mode and the second communication mode.

22. A communication control method for an accessory device, the accessory device being mountable to a camera and communicating with the camera via a channel, the channel comprising a data communication channel for data communication, and a notification channel for notifying timing of communication via the data communication channel, the accessory device being capable of switching between a first communication mode and a second communication mode, the first communication mode being used for communication without specifying a communication partner, and the second communication mode being used for communication between the camera and the accessory device specified as a communication partner, and a voltage level of the notification channel when the accessory device receives data from the camera being different between the first communication mode and the second communication mode, the communication control method comprising the following steps: receiving communication partner designation data from the camera in the first communication mode, the communication partner designation data indicating that the accessory device has been selected as a communication partner with the camera in the second communication mode; as well as When the communication partner designation data is received, switching from the first communication mode to the second communication mode is performed.

23. A communication control method for a camera, the camera being capable of mounting an accessory device, the camera performing communication via a channel, the channel comprising a data communication channel for data communication with the accessory device, and a notification channel for notifying timing of communication performed via the data communication channel, the camera being capable of switching between a first communication mode and a second communication mode, the first communication mode being used for communication without specifying a communication partner, and the second communication mode being used for communication between the camera and the accessory device specified as a communication partner, and a voltage level of the notification channel when the camera transmits data to the accessory device being different between the first communication mode and the second communication mode, the communication control method comprising the following steps: transmitting communication partner designation data to the accessory device in the first communication mode, the communication partner designation data indicating the accessory device selected as the communication partner in the second communication mode; as well as When the communication partner designation data is transmitted, switching is performed from the first communication mode to the second communication mode.

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