JP2011041203A - Communication device, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a source device from erroneously transmitting video data to a sink device. <P>SOLUTION: This communication device includes: a communication means to communicate with an external device via a plurality of transmission lines; a first determination means to determine whether the communication means transmits power to the external device via a first transmission line for transmitting the power to the external device; a second determination means to determine whether the communication means has received a first signal or a second signal via a second transmission line for receiving a signal from the external device; and a control means to control the communication means to acquire the device information of the external device via a third transmission line from the external device in the case that the power is determined to be transmitted to the external device by the first determination means and when the first signal is determined to be received by the second determination means, and to transmit video data to the external device via a fourth transmission line based on the device information. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication device that communicates with an external device and a computer program executed by the communication device.

  Currently, a communication system that conforms to the High Definition Multimedia Interface (HDMI) (registered trademark) standard has been proposed (hereinafter referred to as “HDMI system”). The HDMI system includes a source device that transmits video data and audio data, and a sink device that includes a display device that displays video data received from the source device.

  In order to display the video data from the source device on the sink device, the source device acquires device information of the sink device via a DDC (Display Data Channel) line, and the video data generated according to the device information is sent to the sink device. Need to send.

  In order to acquire device information of the sink device, the source device determines whether the device information can be acquired from the sink device, whether the HPD signal detected via the HPD (Hot Plug Detect) line is at the H level or the L level. Judgment was made depending on whether there was. The HPD signal is a signal transmitted via the HPD line as a response of + 5V power from the sink device when the source device supplies + 5V power to the sink device via the + 5V line. When the source device detects an HPD signal at the H level as a response of + 5V power, the source device acquires the device information of the sink device.

  In the above HDMI system, even when the source device does not supply + 5V power to the sink device via the + 5V power line, the sink device can generate the HPD signal of H by the power supplied via the DDC line. In some cases, the data was transmitted to the source device. In such a case, although the source device does not supply + 5V power to the sink device via the + 5V power line, the source device detects the HPD signal of H and erroneously transmits video data to the sink device. There was a problem that.

  In order to solve the above problem, when the source device does not supply + 5V power to the sink device via the + 5V power line, the source device malfunctions by not outputting the H level HPD signal to the source device. A sink device for preventing the above is known (Patent Document 1).

Special registration 0254895

  However, the above-described sink device has a special resistance element, transistor, etc. in order to control the HPD signal so as not to output the H level HPD signal to the source device even if power is supplied via the DDC line. It was necessary to provide the electronic parts.

  The parameters of these electronic components are the H level HPD signal to the source device when + 5V power is supplied to the sink device via the + 5V power line and when power is supplied via the DDC line. It was necessary to set to switch whether to output.

  As described above, when + 5V power is supplied through the DDC line in a state where + 5V power is not supplied from the source device through the + 5V power line, the sink device having no electronic component described above is in the H level. It was difficult to prevent the HPD signal from being output.

  Therefore, an object of the present invention is to easily prevent the source device from erroneously transmitting video data to the sink device without providing a special electronic component in the sink device.

  The communication device according to the present invention includes a communication unit that communicates with an external device via a plurality of transmission lines, and the communication device transmits the power to the external device via the first transmission line. First determination means for determining whether or not power is being transmitted, and determination as to whether or not the communication means has received a first signal from the external device via the second transmission line from the external device The second determination means and the first determination means determine that the first signal is received by the second determination means when the power is transmitted to the external device. When the device information of the external device is acquired from the external device via a third transmission line, and the video data is transmitted to the external device based on the device information via the fourth transmission line. The communication hand And having a control means for controlling.

  A computer program according to the present invention is a computer program that is executed by a communication device that communicates with an external device via a plurality of transmission lines, and determines whether or not the power is transmitted to the external device. Determining step, a second determining step for determining whether or not the first signal is received from the external device, and the device information of the external device when the first signal is received from the external device. An acquisition step of acquiring, and when the power is transmitted to the external device, and when the first signal is received from the external device, video data is transmitted to the external device based on the device information. And transmitting the transmitting step to the communication device.

  According to the present invention, it is possible to prevent video data from being erroneously transmitted to the sink device in the source device.

It is a figure which shows an example of the communication system which concerns on Example 1 of this invention. It is a block diagram which shows the communication system which concerns on Example 1 of this invention. It is a flowchart which shows the image output control process performed with the communication apparatus 100 which concerns on Example 1 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the following examples are merely examples, and the present invention is not limited to the following examples.

[Example 1]
In the communication system according to the first embodiment, as illustrated in FIG. 1, a communication device 100 and an external device 200 are connected via a connection cable 300.

  The communication device 100 is a video output device that can transmit video data, audio data, and auxiliary data to the external device 200 via the connection cable 300. The external device 200 is a display device that displays video data received from the communication device 100 on a display and outputs audio data received from the communication device 100 from a speaker. Both the communication device 100 and the external device 200 can transmit various control commands bidirectionally via the connection cable 300.

  In the first embodiment, the communication device 100, the external device 200, and the connection cable 300 are assumed to conform to the HDMI standard. Therefore, the communication device 100 is a source device that functions as an HDMI source (Source) in the HDMI standard, and the external device 200 is a sink device that functions as an HDMI sink (Sink) in the HDMI standard.

  In the first embodiment, it is assumed that the communication apparatus 100 and the external apparatus 200 conform to the CEC (Consumer Electronics Control) protocol defined by the HDMI standard. A control command transmitted bidirectionally between the communication device 100 and the external device 200 conforms to the CEC protocol. Hereinafter, a control command conforming to the CEC protocol is referred to as a “CEC command”.

  In the first embodiment, a digital still camera (hereinafter referred to as a camera) is used as an example of the communication device 100. Of course, the communication device 100 is not limited to a digital still camera. As long as the device has a function as an HDMI source device, a video output device such as a single-lens reflex camera, a video camera, a recorder, or a DVD player is used as the communication device 100. It may be used.

  In the first embodiment, a television receiver (hereinafter referred to as “TV”) is used as an example of the external device 200. Of course, the external device 200 is not limited to a television, and a display device such as a projector or a personal computer may be used as the external device 200 as long as the device has a function as an HDMI sink device.

  Hereinafter, the communication device 100 is referred to as “camera 100”, the external device 200 is referred to as “television 200”, and the connection cable 300 is referred to as “HDMI cable 300”.

  Next, the HDMI cable 300 will be described with reference to FIG.

  The HDMI cable 300 includes a + 5V power line 301, a HPD (Hot Plug Detect) line 302, and a DDC (Display Data Channel) line 303. The HDMI cable 300 further includes a TMDS (Transition Minimized Differential Signaling) line 304 and a CEC line 305.

  The + 5V power line 301 (first transmission line) is a power supply line for supplying + 5V power from the camera 100 to the television 200.

  The HPD line 302 (second transmission line) is a transmission line for transmitting a high voltage level (hereinafter, H level) or low voltage level (hereinafter, L level) HPD signal from the television 200 to the camera 100.

  When the camera 100 supplies + 5V power to the television 200 via the + 5V power line 301, the television 200 determines whether the device information of the television 200 can be transmitted to the camera 100.

  The device information of the television 200 is EDID (Extended display identification data) or E-EDID (Enhanced EDID) of the television 200. Both EDID and E-EDID include device information of the television 200, such as identification information of the television 200 relating to the television 200, information relating to the display capability and audio capability of the television 200, and the like. For example, EDID and E-EDID include information on resolution, scanning frequency, aspect ratio, color space, and the like supported by the television 200. E-EDID is an extension of EDID and includes more device information than EDID. For example, the E-EDID includes information related to the format of video data and audio data supported by the television 200. Hereinafter, both EDID and E-EDID are referred to as “EDID”.

  When + 5V power is supplied from the camera 100 to the television 200 and the television 200 can transmit EDID to the camera 100, the television 200 sends an HPD signal (first signal) of H level to the camera 100. Transmit via line 302. The television 200 can inform the camera 100 that the camera 100 can acquire the EDID from the television 200 by transmitting an H level HPD signal to the camera 100.

  Although the camera 100 supplies + 5V power to the television 200, the television 200 may not be able to transmit the EDID of the television 200 to the camera 100. This may be because video settings, resolution settings, audio settings, and the like included in the EDID of the television 200 are changed, and the television 200 is in the process of rewriting information included in the EDID. In this case, the TV 200 transmits an L-level HPD signal (second signal) to the camera 100 via the HPD line 302 until the EDID rewriting is completed. After the EDID rewriting is completed, the television 200 transmits an H level HPD signal to the camera 100 via the HPD line 302. In addition, even when the camera 100 does not supply +5 V power to the television 200, the television 200 transmits an L-level HPD signal to the camera 100.

  The DDC line 303 (third transmission line) is a transmission line for transmitting the EDID of the television 200 from the television 200 to the camera 100. The camera 100 that has received the EDID of the television 200 can automatically know the display capability, audio capability, and the like of the television 200 by referring to the EDID of the television 200. Furthermore, the CPU 101 can automatically know the video format and audio format suitable for the display capability and audio capability of the television 200. By setting the setting of the camera 100 to be suitable for the television 200, the camera 100 converts the video data and audio data transmitted from the camera 100 to the television 200 into video data and audio data suitable for the capability of the television 200. Can do.

  The TMDS line 304 (fourth transmission line) is a transmission line for transmitting video data, audio data, and auxiliary data from the camera 100 to the television 200. The TMDS line 304 includes a TMDS channel 0, a TMDS channel 1, a TMDS channel 2, and a TMDS clock channel.

  The CEC line 305 is a transmission line for bidirectionally transmitting various CEC commands between the camera 100 and the television 200. The television 200 can control the camera 100 by transmitting a CEC command for controlling the camera 100 to the camera 100 via the CEC line 305.

<Camera 100>
Next, an example of the configuration of the camera 100 will be described with reference to FIG.

  As illustrated in FIG. 2, the camera 100 includes a CPU (Central Processing Unit) 101, a memory 102, a communication unit 103, an imaging unit 104, a recording unit 105, a display unit 106, an operation unit 107, and a power supply unit 108. Hereinafter, the camera 100 will be described.

  The CPU 101 controls the operation of the entire camera 100 according to a computer program stored in the memory 102. The CPU 101 can also control the operation of the entire camera 100 using the EDID of the television 200. The CPU 101 controls the entire camera 100 by analyzing data supplied from each unit of the camera 100. Further, the CPU 101 performs control so that power is supplied from the power supply unit 108 to each unit, and control is performed so as to stop power supply.

  The memory 102 functions as a work area for the CPU 101. Information stored in the memory 102 includes an analysis result obtained by the CPU 101 analyzing the EDID of the television 200, the EDID of the television 200, and the like. Further, the memory 102 records flag settings for the operation of each unit, the results of calculations and analysis performed by the CPU 101, and the like. The work area of the CPU 101 is not limited to the memory 102 but may be an external recording device such as a hard disk device.

  The communication unit 103 has a connection terminal for connecting the HDMI cable 300, acquires the EDID of the television 200 via the connection terminal, transmits / receives CEC commands, and transmits video data, audio data, auxiliary data, and the like. Do. The communication unit 103 includes a power transmission unit 103a, a connection detection unit 103b, a capability acquisition unit 103c, and a packet processing unit 103d.

  The power transmission unit 103a is controlled by the CPU 101 to generate + 5V power from the power supplied from the power supply unit 108 and transmit the generated + 5V power to the television 200 via the + 5V power line 301.

  The connection detection unit 103b can receive the HPD signal transmitted from the television 200 via the HPD line 302. When the HPD signal received via the HPD line 302 changes from the HPD signal at the H level to the HPD signal at the L level, the connection detection unit 103b notifies the CPU 101 that the HPD signal has changed from the H level to the L level. . The connection detection unit 103b also notifies the CPU 101 that the HPD signal has changed from the L level to the H level when the HPD signal has changed from the L level HPD signal to the H level HPD signal. When the HPD signal received from the CPU 101 is requested, the connection detection unit 103b supplies the HPD signal to the CPU 101.

  The capability acquisition unit 103 c can acquire EDID from the television 200 via the DDC line 303. When the HPD signal supplied from the connection detection unit 103 b to the CPU 101 is at the H level, the capability acquisition unit 103 c can acquire the EDID of the television 200 from the television 200 via the DDC line 303. When the HPD signal supplied from the connection detection unit 103b to the CPU 101 is at the L level, the capability acquisition unit 103c cannot acquire the EDID from the television 200 via the DDC line 303. When acquiring the EDID, the capability acquisition unit 103 c supplies the acquired EDID to the CPU 101, the CPU 101 analyzes the supplied EDID, and records the supplied EDID and the analysis result of the EDID in the memory 102.

  The packet processing unit 103d can transmit video data, audio data, and auxiliary data to the television 200 via the TMDS line 304. When the operation mode of the camera 100 is the shooting mode, the communication unit 103 sends the video data generated by the imaging unit 104 and the audio data generated by the microphone unit (not shown) to the television 200 via the TMDS line 304. Can be sent. In this case, auxiliary data generated by the CPU 101 is also transmitted to the television 200 through the TMDS line 304 together with video data and audio data. When the operation mode of the camera 100 is the playback mode, the communication unit 103 can transmit the video data and audio data reproduced from the recording medium 105 a by the recording unit 105 to the television 200 via the TMDS line 304. In this case, auxiliary data generated by the CPU 101 is also transmitted to the television 200 through the TMDS line 304 together with video data and audio data. The packet processing unit 103d may transmit video data and audio data separately.

  When the operation mode of the camera 100 is the shooting mode, the imaging unit 104 captures a subject and generates video data from the optical image of the subject. The video data generated by the imaging unit 104 may be either moving image data or still image data. Video data generated by the imaging unit 104 is supplied from the imaging unit 104 to the packet processing unit 103 d, the recording unit 105, and the display unit 106. When the correct EDID can be received from the television 200, the CPU 101 converts the video data supplied from the imaging unit 104 to the packet processing unit 103d into video data suitable for the display capability of the television 200. Video data supplied from the imaging unit 104 to the packet processing unit 103 d is transmitted to the television 200 via the TMDS line 304. The video data supplied from the imaging unit 104 to the recording unit 105 is recorded on the recording medium 105a. The video data supplied from the imaging unit 104 to the display unit 106 is displayed on the display unit 106.

  When the imaging unit 104 generates video data, a microphone unit (not shown) generates audio data. The audio data generated by the microphone unit is supplied from the microphone unit to the packet processing unit 103d, the recording unit 105, and a speaker unit (not shown). When the correct EDID is received from the television 200, the CPU 101 converts the audio data supplied from the microphone unit to the packet processing unit 103d into audio data suitable for the audio capability of the television 200. The audio data supplied from the microphone unit to the packet processing unit 103 d is transmitted to the television 200 via the TMDS line 304. The audio data supplied from the microphone unit to the recording unit 105 is recorded on the recording medium 105a. Audio data supplied from the microphone unit to the display unit 106 is output from a speaker unit (not shown).

  When the operation mode of the camera 100 is the playback mode, the imaging unit 104 stops shooting the subject and stops generating video data from the optical image of the subject.

  When the operation mode of the camera 100 is the shooting mode, the recording unit 105 can record the video data generated by the imaging unit 104 and the audio data generated by the microphone unit on the recording medium 105a. Recording of video data and audio data generated by the imaging unit 104 and the microphone unit on the recording medium 105 a is controlled by the CPU 101 in accordance with a user instruction input via the operation unit 107.

  When the operation mode of the camera 100 is the reproduction mode, the recording unit 105 can reproduce the video data and audio data selected by the user from the recording medium 105a. Selection of video data and audio data reproduced from the recording medium 105 a is controlled by the CPU 101 in accordance with a user instruction input via the operation unit 107.

  Video data reproduced from the recording medium 105 a by the recording unit 105 is supplied from the recording unit 105 to the packet processing unit 103 d and the display unit 106. When the correct EDID is received from the television 200, the CPU 101 converts the video data supplied from the recording unit 105 to the packet processing unit 103d into video data suitable for the display capability of the television 200 according to the EDID. The video data supplied from the recording unit 105 to the packet processing unit 103 d is transmitted to the television 200 via the TMDS line 304. The video data supplied from the recording unit 105 to the display unit 106 is displayed on the display unit 106. The audio data reproduced by the recording unit 105 from the recording medium 105a is supplied from the recording unit 105 to the packet processing unit 103d and a speaker unit (not shown). When the correct EDID is received from the television 200, the CPU 101 converts the audio data supplied from the recording unit 105 to the packet processing unit 103d into audio data suitable for the audio capability of the television 200 according to the EDID. The audio data supplied from the recording unit 105 to the packet processing unit 103d is transmitted to the television 200 via the TMDS line 304. The audio data supplied from the recording unit 105 to the speaker unit is output from the speaker unit.

  The recording medium 105a is a recording medium such as a memory card or a hard disk device. The recording medium 105 a may be a recording medium built in the camera 100 or a recording medium removable from the camera 100.

  The display unit 106 includes a display device such as a liquid crystal display. When the operation mode of the camera 100 is the shooting mode, the display unit 106 displays the video data generated by the imaging unit 104. When the operation mode of the camera 100 is the reproduction mode, the display unit 106 displays the video data reproduced by the recording unit 105 from the recording medium 105a.

  The operation unit 107 provides a user interface for operating the camera 100. The operation unit 107 has a plurality of buttons for operating the camera 100. Each button included in the operation unit 107 includes a switch, a touch panel, and the like. The CPU 101 can control the camera 100 in accordance with a user instruction input via the operation unit 107.

  The operation unit 107 includes a power button for changing the camera 100 to a power-on state or a power-off state, a mode change button 107a for changing the operation mode of the camera 100 from a shooting mode to a playback mode, and the like. Note that the power-off state is a state where power supply from the power supply unit 108 to a part or all of the camera 100 is stopped, and the power-on state is a state where the power supply unit 108 supplies a part or all of the camera 100 In this state, power is being supplied. The power supply unit 108 supplies necessary power to each unit of the camera 100 from a battery that can be attached to and detached from the camera 100, an AC power source, or the like.

<TV 200>
Next, an example of the configuration of the television 200 will be described with reference to FIG.

  As illustrated in FIG. 2, the television 200 includes a CPU 201, a tuner unit 202, a communication unit 203, a display unit 204, an operation unit 205, a memory 206, and a power supply unit 207.

  The CPU 201 controls the overall operation of the television 200 according to a computer program stored in the memory 206. Further, the CPU 201 performs control so that power is supplied from the power supply unit 207 to each unit, and control is performed so as to stop power supply.

  The tuner unit 202 receives a television broadcast of the television channel selected by the user. The television channel can be selected using the operation unit 205 or a remote controller (not shown). The CPU 201 controls the tuner unit 202 in accordance with a user instruction input via the operation unit 205. Thereby, the tuner unit 202 can receive a television broadcast of a television channel selected by the user using a remote controller (not shown) or the operation unit 205. Video data included in the television broadcast received by the tuner unit 202 is displayed on the display unit 204. Audio data included in the television broadcast received by the tuner unit 202 is output from a speaker unit (not shown). The auxiliary data included in the television broadcast received by the tuner unit 202 is supplied to the CPU 201. The CPU 201 can control the television 200 according to the auxiliary data received from the camera 100.

  The communication unit 203 has a connection terminal for connecting the HDMI cable 300. The communication unit 203 can receive the video data, audio data, and auxiliary data transmitted from the camera 100 via the TMDS line 304. Video data received from the camera 100 is displayed on the display unit 204. Audio data received from the camera 100 is output from a speaker unit (not shown). The auxiliary data received from the camera 100 is supplied to the CPU 201. The CPU 201 can control the television 200 according to the auxiliary data received from the camera 100.

  Note that the number of connection terminals included in the communication unit 203 is arbitrary depending on the television 200, and the television 200 can connect source devices other than the camera 100 via the HDMI cable by the number of connection terminals. Therefore, the television 200 can receive video data, audio data, and auxiliary data transmitted from a source device other than the camera 100 connected via the HDMI cable. In this case, like the camera 100, video data received from a source device other than the camera 100 is displayed on the display unit 204, audio data is output from a speaker unit (not shown), and auxiliary data is supplied to the CPU 201.

  The communication unit 203 can receive the CEC command transmitted from the camera 100 via the CEC line 305 and transmit the CEC command generated by the CPU 201.

  The communication unit 203 determines whether or not the camera 100 is supplying + 5V power to the television 200 via the + 5V power line 301, and outputs an H level HPD signal or an L level HPD signal according to the determination result. Via the HPD line 302. When the communication unit 203 has not acquired + 5V power from the camera 100 via the + 5V power line 301, the CPU 201 controls the communication unit 203 to transmit an L level HPD signal to the camera 100 via the HPD line 302. .

  When the communication unit 203 acquires + 5V power from the camera 100 via the + 5V power line 301, the CPU 201 determines whether or not the EDID of the television 200 stored in the memory 206 can be transmitted to the camera 100 via the DDC line 303. judge. When the information included in the EDID stored in the memory 206 has not been changed, or when the EDID has been rewritten, the CPU 201 can transmit the EDID of the television 200 to the camera 100 via the DDC line 303. Is determined. In this case, the CPU 201 controls the communication unit 203 so as to transmit the HPD signal at the H level to the camera 100 via the HPD line 302. When the information included in the EDID is rewritten due to a change in the setting for the television 200, the CPU 201 determines that the EDID of the television 200 cannot be transmitted to the camera 100 via the DDC line 303. Also in this case, the CPU 201 controls the communication unit 203 to transmit the L level HPD signal to the camera 100 via the HPD line 302.

  Further, the communication unit 203 can transmit the EDID of the television 200 to the camera 100 via the DDC line 303.

  The display unit 204 includes a display device such as a liquid crystal display. The display unit 204 can display video data supplied from at least one of the tuner unit 202 and the communication unit 203. When the video data received from the camera 100 is supplied by the communication unit 203, the display unit 204 displays the video data received from the camera 100.

  The operation unit 205 provides a user interface for operating the television 200. The operation unit 205 has a plurality of buttons for operating the television 200. Each button included in the operation unit 205 includes a switch, a touch panel, and the like. The CPU 201 can control the television 200 in accordance with a user instruction input via the operation unit 205. The operation unit 205 includes a power button for operating the television 200, a channel selection button, an external input button, and the like.

  The power button is a button for instructing the CPU 201 to change the television 200 to a power-on state or a power-off state. The power-on state is a state in which the CPU 201 controls the power supply unit 207 so as to supply necessary power to all the units of the television 200. The power-off state is a state in which the CPU 201 controls the power supply unit 108 so as to stop supplying power to a part of the television 200 or all the units of the television 200.

  The channel selection button is a button for selecting a television channel received by the tuner unit 202.

  The external input button selects video data included in the television broadcast received by the tuner unit 202 or video data received from the camera 100 connected via the HDMI cable 300, and displays the selected video data on the display unit 204. It is a button to make it.

  The power supply unit 207 supplies necessary power to each unit of the television 200 from an AC power supply or the like.

<Image control processing>
Next, with reference to FIG. 3, an image output control process performed by the camera 100 according to the first embodiment will be described.

  FIG. 3 is a flowchart for explaining an example of the image output control process performed by the camera 100 according to the first embodiment. The image output control process is performed when the camera 100 is in a power-on state and the operation mode of the camera 100 is the playback mode. It is assumed that the HDMI cable 300 is physically connected to the connection terminal of the camera 100 and the connection terminal of the television 200.

  Note that the image output control process is controlled by the CPU 101 executing a computer program stored in the memory 102. Further, a computer program for causing the camera 100 to execute the image output control process shown in FIG. 3 uses an OS (Operating System), a network, etc. running on a computer (CPU, MPU, etc.). It may be realized.

  In step S301, the CPU 101 determines whether or not the operation mode of the camera 100 has been changed from another operation mode to the playback mode. The CPU 101 can determine whether or not the operation mode of the camera 100 has been changed from another operation mode to the playback mode based on the presence or absence of a mode change signal input from the mode change button 107a of the operation unit 107. When a mode change signal is input from the mode change button 107a, the CPU 101 determines that the operation mode of the camera 100 has been changed from another operation mode to the playback mode. In this case (YES in step S301), the flowchart proceeds from step S301 to step S302. When the mode change signal is not input from the mode change button 107a, the CPU 101 determines that the operation mode of the camera 100 is not changed and remains in the reproduction mode. In this case (if NO in step S301), the flowchart proceeds from step S301 to step S304. When the operation mode of the camera 100 is changed from the other operation mode to the playback mode (YES in step S301), the CPU 101 determines whether the camera 100 can transmit video data or the like to the television 200 via the HDMI cable 300. It is necessary to judge.

  Therefore, in step S302, the CPU 101 determines whether or not the camera 100 is ready for image output. The image output enabled state is a state in which the camera 100 is set to transmit video data to the television 200 via the communication unit 103 and the HDMI cable 300. If the CPU 101 determines that the camera 100 is ready to output images (YES in step S302), the process proceeds from step S302 to step S303. If the CPU 101 determines that the camera 100 is not ready for image output (NO in step S302), the process proceeds from step S302 to step S308.

  When the camera 100 is ready to output images (in the case of YES in step S302), in order for the camera 100 to transmit video data to the television 200 via the TMDS line 304, the EDID of the television 200 is acquired and the EDID is stored. It is necessary to generate suitable video data. In order for the camera 100 to obtain the EDID of the television 200, the camera 100 needs to transmit + 5V power to the television 200 via the + 5V power line.

  Therefore, in step S303, the CPU 101 controls the power supply unit 108 to supply necessary power to the power transmission unit 103a, thereby changing the power transmission unit 103a from the low power consumption state to the normal state. The normal state in the power transmission unit 103a is a state in which power for transmission to the television 200 via the + 5V power line 301 is supplied from the power supply unit 108 controlled by the CPU 101 to the power transmission unit 103a. The low power consumption state in the power transmission unit 103a is a state in which power for transmitting to the television 200 via the + 5V power line 301 is not supplied from the power supply unit 108 controlled by the CPU 101 to the power transmission unit 103a. It is.

  The CPU 101 controls the power supply unit 108 to control the power transmission unit 103a to transition from the normal state to the low power consumption state, or to transition from the low power consumption state to the normal state.

  The power transmission unit 103 a in the normal state generates + 5V power from the power supplied from the power supply unit 108, and transmits it to the television 200 via the + 5V power line 301. After the power transmission unit 103a transmits + 5V power to the television 200 via the + 5V power line 301, the flowchart proceeds from step S303 to step S305.

  If the mode change signal is not input (NO in step S301), the camera 100 remains in the playback mode, and + 5V power is already supplied to the television 200 via the + 5V power line 301 by the power transmission unit 103a. it is conceivable that. Therefore, when the power transmission unit 103a supplies + 5V power to the television 200, the CPU 101 needs to determine whether there is a change in the HPD signal detected by the connection detection unit 103b.

  In step S304, the CPU 101 determines whether there is a change in the HPD signal detected by the connection detection unit 103b. If the CPU 101 determines that a change in the HPD signal has been detected (YES in step S304), the flowchart proceeds from step S304 to step S305. When it is determined by the CPU 101 that no change in the HPD signal has been detected (NO in step S304), the flowchart returns from step S304 to step S301.

  After the power transmission unit 103a transmits + 5V power to the television 200 via the + 5V power line 301 in step S303, the CPU 101 detects the connection detection unit 103b to determine whether or not the EDID of the television 200 can be acquired. It is necessary to check the HPD signal.

  When a change in the HPD signal is detected (YES in step S304), the CPU 101 needs to confirm whether the HPD signal detected by the connection detection unit 103b is at the H level or the L level.

  In step S305, the CPU 101 determines, as a first determination, whether the HPD signal detected by the connection detection unit 103b is at the H level. When the CPU 101 determines that the HPD signal detected by the connection detection unit 103b is at the H level (YES in step S305), the process proceeds from step S305 to step S306. When the CPU 101 determines that the HPD signal detected by the connection detection unit 103b is not at the H level, that is, the HPD signal is at the L level (NO in step S305), the process proceeds from step S305 to step S309. .

  Even when the power transmission unit 103a does not transmit + 5V power to the television 200 via the + 5V power line 301, it is assumed that the connection detection unit 103b detects an H-level HPD signal transmitted from the television 200. Is done. Therefore, if the HPD signal detected by the connection detection unit 103b is at the H level (YES in step S305), whether or not the power transmission unit 103a transmits + 5V power to the television 200 via the + 5V power line 301. It is necessary to determine whether. This is performed in advance to prevent the camera 100 from erroneously transmitting video data to the sink device.

  Therefore, in step S306, as a second determination, the CPU 101 determines whether the power transmission unit 103a is transmitting + 5V power to the television 200 via the + 5V power line 301.

  When the CPU 101 determines that the power transmission unit 103a is transmitting + 5V power to the television 200 via the + 5V power line 301 (YES in step S306), the process proceeds from step S306 to step S307. When the CPU 101 determines that the power transmission unit 103a is not transmitting + 5V power to the television 200 via the + 5V power line 301 (NO in step S306), the flowchart returns from step S306 to step S301. In this case, since the communication between the camera 100 and the television 200 becomes unstable, the camera 100 cannot acquire the EDID of the television 200 in which an error has occurred from the television 200 or cannot transmit video data suitable for the television 200. . Even if the camera 100 can transmit video data suitable for the television 200, communication between the camera 100 and the television 200 is interrupted while the camera 100 is transmitting video data to the television 200. In order to prevent such a situation, the CPU 101 controls the video data of the camera 100 not to be transmitted to the television 200 when the power transmission unit 103a does not transmit + 5V power to the television 200 via the + 5V power line 301.

  When the power transmission unit 103a is transmitting + 5V power to the television 200 via the + 5V power line 301 (YES in step S306), the CPU 101 receives an EDID from the television 200 in order to transmit video data to the television 200. Need to get.

  In step S307, the CPU 101 controls the power supply unit 108 so as to supply necessary power to the capability acquisition unit 103c and the packet processing unit 103d. When power is supplied from the power supply unit 108 to the capability acquisition unit 103c, the capability acquisition unit 103c can acquire the EDID of the television 200 via the DDC line 303. When power is supplied to the packet processing unit 103d from the power supply unit 108, the packet processing unit 103d can transmit video data to the television 200 via the TMDS line 304.

  When power is supplied from the power supply unit 108 to the capability acquisition unit 103c and the packet processing unit 103d, the capability acquisition unit 103c acquires the EDID of the television 200 via the DDC line 303 and supplies it to the CPU 101. After the CPU 101 analyzes the EDID of the television 200 supplied from the capability acquisition unit 103c and records the EDID and the EDID analysis result in the memory 102, the CPU 101 is suitable for displaying the video data on the television 200 according to the EDID analysis result. Change to the selected video format. The video data changed to the video format of the television 200 by the CPU 101 is supplied to the packet processing unit 103d, and is transmitted to the television 200 via the TMDS line 304 by the packet processing unit 103d.

  When the video data is transmitted by the packet processing unit 103d, the flowchart returns from step S307 to step S301.

  If the camera 100 is not ready for image output (NO in step S302), it is not necessary to acquire EDID from the television 200 and transmit video data to the television 200 until the camera 100 is ready for image output. Therefore, in step S308, the CPU 101 controls the power supply unit 108 so as not to supply necessary power to the power transmission unit 103a. When the necessary power is already supplied to the power transmission unit 103a and the power transmission unit 103a is in the normal state, the CPU 101 controls the power supply unit 108 to change the power transmission unit 103a from the normal state to the low power consumption state. To change.

  When the HPD signal detected by the connection detection unit 103b is at the L level (NO in step S305), the television 200 cannot transmit the EDID to the camera 100, or the television 200 is rewriting information included in the EDID. A state is assumed. For this reason, even if the camera 100 transmits video data to the television 200, there is a high possibility of transmitting video data that is not suitable for display on the television 200. In such a case, the video data transmitted from the camera 100 is not correctly received by the television 200, and the received video data is not always correctly displayed on the television 200.

  In addition, when the power transmission unit 103a stops transmitting + 5V power to the television 200 in step S308, even if the HDMI cable 300 is inserted into the connection terminal of the camera 100 and the connection terminal of the television 200, between both devices. There is no communication.

  Therefore, in step S309, the CPU 101 determines whether the packet processing unit 103d is transmitting video data to the television 200 via the TMDS line 304. If the CPU 101 determines that the packet processing unit 103d is transmitting video data to the television 200 via the TMDS line 304 (YES in step S309), the process proceeds from step S309 to step S310. If the CPU 101 determines that the packet processing unit 103d is not transmitting video data to the television 200 via the TMDS line 304 (NO in step S309), the process returns from step S309 to step S301.

  When the packet processing unit 103d is transmitting video data to the television 200 via the TMDS line 304 (YES in step S309), there is a high possibility that the packet processing unit 103d consumes extra power. Therefore, in step S310, the CPU 101 supplies power so as not to supply necessary power to the capability acquisition unit 103c and the packet processing unit 103d in order to stop transmission of video data to the television 200 and acquisition of EDID from the television 200. The unit 108 is controlled. In this case, the power acquisition unit 103c and the packet processing unit 103d are changed from the normal state to the low power consumption state by the power supply unit 108 controlled by the CPU 101.

  The normal state in the capability acquisition unit 103c is a state in which power necessary for acquiring EDID from the television 200 is supplied from the power supply unit 108 controlled by the CPU 101 to the capability acquisition unit 103c. The normal state in the packet processing unit 103d is a state in which power necessary for transmitting video data, audio data, auxiliary data, and the like is supplied from the power supply unit 108 controlled by the CPU 101 to the packet processing unit 103d. .

  The low power consumption state in the capability acquisition unit 103c is a state in which the power supply unit 108 does not supply the capability acquisition unit 103c with power necessary for the capability acquisition unit 103c to acquire EDID from the television 200. The low power consumption state in the packet processing unit 103d means that the power supply unit 108 supplies the packet processing unit 103d with power necessary for the packet processing unit 103d to transmit video data, audio data, auxiliary data, and the like to the television 200. There is no state.

  By controlling the power supply unit 108, the CPU 101 controls the capability acquisition unit 103c and the packet processing unit 103d to transition from the normal state to the low power consumption state, or to transition from the low power consumption state to the normal state. To do.

  When the supply of power from the power supply unit 108 to the capability acquisition unit 103 c is stopped, the capability acquisition unit 103 c stops acquiring the EDID of the television 200 via the DDC line 303. When the supply of power from the power supply unit 108 to the packet processing unit 103d is stopped, the packet processing unit 103d stops transmission of video data to the television 200 via the TMDS line 304. When the supply of power from the power supply unit 108 to the capability acquisition unit 103 c and the packet processing unit 103 d is stopped, the CPU 101 deletes the EDID and EDID analysis results of the television 200 recorded in the memory 102. Further, the CPU 101 stops the process of converting the video data into a video format obtained from the EDID analysis result. When the capability acquisition unit 103c and the packet processing unit 103d are changed from the normal state to the low power consumption state, the flowchart returns from step S310 to step S301. Note that the CPU 101 controls the power supply unit 108 to supply necessary power to the connection detection unit 103b so that the connection detection unit 103b always detects a change in the HPD signal.

  As described above, in the camera 100 according to the first embodiment, the video data is transmitted to the television 200 according to the determination as to whether EDID can be acquired from the television 200 and the determination as to whether +5 V power is transmitted to the television 200. It became possible to control sending. For this reason, even if it is determined that the camera 100 can acquire EDID from the TV 200, if + 5V power is not transmitted to the TV 200, processing relating to transmission of video data is not performed. Can be prevented in advance. In addition, when + 5V power is not transmitted to the television 200, the camera 100 does not perform processing related to acquisition of EDID or transmission of video data, so that the power consumption of the camera 100 is reduced and the processing load performed by the camera 100 Can be reduced.

  In addition, even when the camera 100 stops transmitting + 5V power to the television 200, cannot acquire EDID from the television 200, or transmits video data to the television 200, the camera 100 acquires EDID or transmits video data. Cancel. For this reason, the power consumption of the camera 100 can be reduced.

  Note that the camera 100 according to the first embodiment performs the image output control process illustrated in FIG. 3 when the operation mode of the camera 100 is the playback mode. However, when the operation mode of the camera 100 is other than the playback mode and the camera 100 is changed to an operation mode for transmitting video data to an external device via the TMDS line 304, the camera 100 similarly performs the output control process. You can go. For example, in step S <b> 301, the CPU 101 may determine whether the operation mode of the camera 100 is the shooting mode and whether the live view video or the preview video is set to be transmitted to the television 200. In this case, the processing performed after the determination in step S301 executes the processing from step S302 to step S310 of the image output control processing shown in FIG. Further, the above example is merely an example, and the CPU 101 similarly performs the image output control process even when the operation mode of the camera 100 is a specific mode other than the playback mode and the shooting mode. May be.

  Note that even if the camera 100 and the television 200 in the first embodiment are devices that do not comply with the CEC protocol, the camera 100 can obtain the same effect by executing the image output control process.

  In the first embodiment, the communication apparatus 100 has been described as a source apparatus compatible with the HDMI standard, and the external apparatus 200 has been described as a sink apparatus compatible with the HDMI standard. However, the image output control process described in the first embodiment is executed. If possible, it is not limited to this. Further, although the connection cable 300 has been described as an HDMI cable compatible with the HDMI standard, the present invention is not limited thereto, and a cable compatible with USB or IEEE1394 may be used. In addition, the connection cable 300 may be a cable compatible with DiIVA (Digital Interactive Interface for Video and Audio).

[Other embodiments]
The communication apparatus according to the present invention is not limited to the communication apparatus 100 described in the first embodiment, and may be realized by a system including a plurality of apparatuses, for example. Further, according to the present invention, the processing for realizing the functions of the first embodiment described above can be realized by a computer program. In this case, the computer program is read and executed by a computer from a computer-readable recording medium. The computer program may be supplied to an apparatus or system and executed by the computer of the apparatus or system.

  As the computer-readable recording medium, a hard disk device, an optical disk, a CD-ROM, a CD-R, a memory card, a ROM, or the like can be used. The computer program may be provided from an external device to a computer via a communication interface and executed by the computer.

Claims (9)

A communication means for communicating with an external device via a plurality of transmission lines;
First determination means for determining whether or not the communication means is transmitting the power to the external device via a first transmission line for transmitting power to the external device;
Second determining means for determining whether or not the communication means has received a first signal from the external device via the second transmission line;
In the case where the power is transmitted to the external device by the first determination unit and the second determination unit determines that the first signal has been received, Control means for acquiring device information of the external device via the third transmission line and controlling the communication means to transmit video data to the external device based on the device information via the fourth transmission line And a communication device.   When it is determined that the power is not transmitted to the external device by the first determination unit, and the second determination unit determines that the first signal is received, the control 2. The communication apparatus according to claim 1, wherein means controls the communication means so as not to acquire the device information from the external apparatus and not to transmit the video data.   The communication apparatus according to claim 1, wherein the first signal is a signal indicating that device information of the external apparatus can be acquired.   When the second determination unit determines that the second signal is received from the external device, the control unit does not acquire the device information from the external device and does not transmit the video data. 4. The communication device according to claim 1, wherein the communication unit is controlled.   The control means acquires device information of the external apparatus from the external apparatus and controls the communication means to transmit the video data to the external apparatus, and the second determination means When it is determined that the second signal has been received, the control unit deletes the device information acquired from the external device and controls the communication unit to stop transmission of the video data. The communication device according to claim 4. The communication means further comprises power supply means for supplying power to the communication means for communicating with the external device via the third transmission line and the fourth transmission line;
If it is determined by the second determination means that the second signal has been received, the control means stops the power supplied to the communication means by the power supply means, thereby causing the external device to Controlling the communication means so as not to acquire the device information via a third transmission line and to prevent the video data from being transmitted to the external device via the second transmission line. The communication device according to claim 4, wherein:   The communication apparatus according to claim 4, wherein the second signal is a signal indicating that device information of the external apparatus cannot be acquired.   The communication apparatus according to claim 1, wherein the communication unit conforms to an HDMI standard. A computer program to be executed by a communication device that communicates with an external device via a plurality of transmission lines,
A first determination step of determining whether or not the power is transmitted to the external device;
A second determination step of determining whether or not a first signal is received from the external device;
An acquisition step of acquiring device information of the external device when the first signal is received from the external device;
A transmission step of transmitting video data to the external apparatus based on the device information when the first signal is received from the external apparatus when the power is transmitted to the external apparatus. A computer program executed by the communication apparatus.

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