JP5007657B2 - COMMUNICATION SYSTEM, ELECTRONIC DEVICE, AND COMMUNICATION METHOD - Google Patents

Description

  The present invention relates to a communication system, an electronic device, and a communication method having a communication interface such as HDMI (High Definition Multimedia Interface) capable of transmitting pixel data of an uncompressed image in one direction at high speed.

The HDMI specification “High-Definition Multimedia Interface Specification Version 1.3a” is distributed from HDMI LLC (http://www.hdmi.org/).
In the HDMI standard, a transmitter device is referred to as a source device, and a receiver device is referred to as a sink device.

  The HDMI source and the HDMI sink have an HDMI connector to which an HDMI cable including a plurality of signal lines is connected. This HDMI connector is a connector for transmitting image data and audio data by digital signals.

  In the HDMI specification, for HDMI, TMDS (Transition Minimized Differential Signaling) channel that transmits pixel data and audio data in one direction from HDMI source to HDMI sink at high speed, or between HDMI source and HDMI sink A CEC line (Consumer Electronics Control Line) for performing bidirectional communication is defined.

  In recent years, for example, a digital television signal, that is, a non-display signal from a DVD (Digital Versatile Disc) recorder, a set-top box, or other AV (Audio Visual) source to a television receiver, projector, or other display. HDMI (R) is becoming popular as a communication interface that transmits pixel data of a compressed (baseband) image and audio data accompanying the image at high speed.

An HDMI port for output is attached to a recent DVD, and an HDMI port for input is attached to a television receiver or the like.
In addition, cases in which a personal computer (hereinafter referred to as a PC) and a home video camera are equipped with an HDMI port for outputting to a television receiver are increasing.

  By the way, regarding HDMI (R), when pixel data and audio data are transmitted from an HDMI (R) source to an HDMI (R) sink, unnecessary data is muted by turning on / off data transmission. An apparatus has been proposed (see, for example, Patent Document 1).

  Further, for HDMI (R), a cable that connects an HDMI (R) source and an HDMI (R) sink by switching the terminal from which the HDMI (R) source outputs pixel data and audio data using a changeover switch. There is proposed a device that can output pixel data and audio data to a desired HDMI (R) sink among a plurality of HDMI (R) sinks without replacing (see, for example, Patent Document 2). ).

JP-A-2005-57714 JP 2006-19948 A

However, since the HDMI port defined in the above standard is dedicated to either output or input, for example, the HDMI port of a home video camera is connected to the HDMI port equipped on the PC, and the video is transferred to the PC. It is not possible.
In addition, when the output and input ports are connected to each other, the shape of the connector is the same, so that a physical connection is possible, but the user cannot recognize an erroneous connection.
Therefore, the current HDMI terminal including the devices described in Patent Document 1 and Patent Document 2 has the following problems.

If the user misconnects the receiver devices and the transmitter devices, there is a possibility of device failure.
When the user incorrectly connects the receiver devices and the transmitter devices, the user cannot be notified of the incorrect connection, although it does not operate correctly.

  In addition, it is considered that there is a demand for sharing connectors using the same shape of connectors in small devices. However, in the current technology, receivers and transmitters are connected via analog switches etc. before the user connects them. It is necessary to specify in advance which of these will work. The method of setting in advance is cumbersome as an operation method and reduces the convenience for the user.

  The HDMI specification only states that if two receiver devices are connected to each other, they will not be damaged when two transmitter devices are connected to each other, and a specific method for preventing damage is described. Not.

There is also a standard called UDI (Unified Display Interface) defined by an organization called UDI SIG. In this UDI, the cable has a different external shape to prevent erroneous connection of the cable.
However, in the method of changing the outer shape to prevent erroneous connection, the user needs to be aware of the direction of the cable at the time of connection, which causes a decrease in convenience in another aspect.
Moreover, it is difficult to realize a method of preventing erroneous connection by changing the external shape at the same time as a function of using one connector as a transmitter and a receiver.
The UDI specification “Unified Display Interface (UDI) Specification” is distributed at UDI SIG (http://www.udiwg.org/home).

  The present invention provides a communication system, an electronic device, and a communication method that can detect the type of a connected device and can improve convenience without requiring a troublesome labor with only one connector portion. It is to provide.

  A communication system according to a first aspect of the present invention includes a connector portion to which a communication cable can be connected, and the communication cable is a single transmission of video and audio data, exchange of connected device information, and device control data. A communication system between electronic devices capable of communication, wherein the electronic device can have at least one of a transmitter function and a receiver function, and the communication cable has a predetermined voltage by the transmitter. A voltage of the first signal line that can be connected to the connector portion, and a second signal line that is driven to a predetermined voltage by a receiver. Alternatively, a detection control unit that detects the voltage of the second signal line and determines whether the connection-side electronic device is a receiver or a transmitter is provided.

  A second aspect of the present invention includes a connector portion to which a communication cable can be connected, and the communication cable can be used for data transmission of video and audio, exchange of connected device information, and communication of device control data. And an electronic device capable of having at least one of a transmitter function and a receiver function, wherein the communication cable includes a first signal line driven to a predetermined voltage by the transmitter. A second signal line driven to a predetermined voltage by a receiver, and the electronic device uses the voltage of the first signal line or the voltage of the second signal line connectable to the connector unit. It has a detection control unit that detects and determines whether the connection partner electronic device is a receiver or a transmitter.

  Preferably, the information processing apparatus has a notification unit having a notification function, and the detection control unit determines that the device is a transmitter and the connection partner is not a receiver, or that the device is a receiver and the connection partner is not a transmitter. In such a case, the notification unit notifies that the connection is incorrect.

  Preferably, the detection control unit has a function of retaining the connection when it is determined in the determination process that the receivers or the transmitters are connected.

  Preferably, the detection control unit has a function of automatically switching whether the own device operates as a receiver or a transmitter based on information detected and discriminated.

  Preferably, when the own device functions as a transmitter, the detection control unit applies the voltage intermittently to the first signal line in order to correctly start communication so that the own device is determined as the transmitter. Thus, the communication function can be started.

  Preferably, the detection control unit randomly increases an interval between voltages applied intermittently to the first signal line, thereby increasing a possibility that the own device is identified as a transmitter and starting communication. It has a function that can.

  Preferably, when the own device functions as a receiver, the detection control unit applies the voltage intermittently to the second signal line in order to correctly start communication, thereby determining the own device as the receiver. Thus, the communication function can be started.

  Preferably, the detection control unit randomly increases an interval between voltages applied intermittently to the second signal line, thereby increasing a possibility that the own device is determined as a receiver and starting communication. It has a function that can.

  Preferably, when the self-device functions as a receiver or transmitter, the detection control unit selectively selects a voltage intermittently between the second signal line and the first signal line in order to correctly start communication. By applying the function, it is possible to start communication when the own device is identified as a receiver or a transmitter.

  Preferably, the detection control unit randomly determines an interval between voltages applied intermittently to the second signal line or the first signal line so that the own device is determined as a receiver or a transmitter. It has a function that can increase the possibility of communication and start communication.

  Preferably, by connecting at least one of the first signal line and the second signal line to the same state as when the cable is disconnected by dropping the voltage, and then reconnecting again, the connection counterpart device A function to re-establish connection with

  Preferably, the detection control unit has an operation mode in which the automatic switching is temporarily disabled by determining in advance whether to operate as a receiver or a transmitter.

  Preferably, the detection control unit has a function of detecting insertion / removal of the communication cable or power-off even when automatic switching is performed once, and returning to a state before detection again.

  Preferably, when the own device functions as a receiver, the detection control unit applies the voltage intermittently to the second signal line in order to correctly start communication, thereby determining the own device as the receiver. After the connection, device information is exchanged using EDID, and based on the information detected and determined, whether the device operates as a receiver or a transmitter When it is found that the devices have a function of automatically switching, a function is provided for reselecting which one is a transmitter.

  A third aspect of the present invention includes a connector portion to which a communication cable can be connected, and the communication cable can be used to transmit video and audio data, exchange connected device information, and communicate device control data. A communication method between electronic devices, wherein the electronic device can have at least one of a transmitter function and a receiver function, and the communication cable is driven to a predetermined voltage by the transmitter. A first signal line and a second signal line driven to a predetermined voltage by a receiver, and the voltage of the first signal line or the second signal line connectable to the connector portion The voltage is detected to determine whether the connection partner electronic device is a receiver or a transmitter, and to determine whether communication is possible.

  According to the present invention, the detection control unit detects the voltage of the first signal line or the voltage of the second signal line that can be connected to the connector unit. Then, the detection control unit determines whether the connection partner electronic device is a receiver or a transmitter based on the detection result.

  According to the present invention, there is an advantage that it is possible to detect the type of the connected device with only one connector portion without requiring troublesome work and to improve convenience.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration example of a main part of a communication system according to an embodiment of the present invention.

The communication system 100 includes a TMDS (Transition Minimized Differential Signaling) channel that transmits pixel data and audio data in one direction from an HDMI source to an HDMI sink at high speed.
In addition, the communication system 100 can be configured as a system that performs video and audio data transmission, exchange and authentication of connected device information, communication of device control data, and LAN communication with a single communication cable.

The communication system 100 includes a transmitter 110 represented as a source device in the HDMI standard, a receiver 120 represented as a sink device, a transmitter 110 and a receiver 120. And an HDMI cable 130 which is a communication cable.
The transmitter 110 is disposed in the communication interface unit of the electronic device 101 that functions as the source device, and the receiver 120 is disposed in the communication interface unit of the electronic device 102 that functions as the sink device.

  The transmitter 110 and the receiver 120 have HDMI connector portions 111 and 121 as connection portions to which the HDMI cable 130 is connected.

  The transmitter 110 converts, for example, pixel data of an uncompressed image into a corresponding differential signal, and is connected via the HDMI cable 130 with three TMDS channels # 0, # 1, and # 2 that are a plurality of channels. The receiver 120 (HDMI sink) has a signal transmission unit 112 for serial transmission in one direction.

  In addition, the transmitter 110 converts audio data associated with an uncompressed image, further necessary control data and other auxiliary data, etc. into corresponding differential signals, and converts them into three TMDS channels # 0, # 1, #. 2 is serially transmitted in one direction to the receiver 120 connected via the HDMI cable 130.

  Further, the transmitter 110 transmits the pixel clock synchronized with the pixel data transmitted through the three TMDS channels # 0, # 1, and # 2 to the receiver 120 connected via the HDMI cable 13 through the TMDS clock channel. . Here, in one TMDS channel #i (i = 0, 1, 2), 10-bit pixel data is transmitted during one pixel clock.

  The receiver 120 transmits TMDS channels # 0, # 1, and # 2 in one direction from the transmitter 110 connected via the HDMI cable 130, the differential signal corresponding to the pixel data, the audio data, The receiver 122 receives the differential signal corresponding to the control data in synchronization with the pixel clock transmitted from the transmitter 110 via the TMDS clock channel.

  Next, with reference to FIG. 2 and FIG. 3, the pin assignment of the HDMI connector units 111 and 121 provided in the transmitter 110 or the receiver 120 connected to the HDMI cable 130 will be described.

  2 and 3, the left column (PIN column) describes the pin number identifying the connector pin, and the right column (Signal Assignment column) lists the left column in the same row. The name of the signal assigned to the pin specified by the pin number is indicated.

  FIG. 2 shows a connector pin arrangement called HDMI type A (Type-A).

  Two signal lines, which are differential signal lines through which the differential signals TMDS Data # i + and TMDS Data # i− of the TMDS channel #i are transmitted, are assigned to the pins to which TMDS Data # i + is assigned (the pin number is 1). , 4, 7) and pins assigned with TMDS Data # i- (pin numbers 3, 6 and 9).

  A CEC line (not shown in FIG. 1) through which a CEC signal as control data is transmitted is connected to a pin having a pin number of 13, and a pin having a pin number of 14 is a reserved pin. Yes. If bi-directional IP communication can be performed using this empty pin, compatibility with the current HDMI can be maintained. Therefore, the CEC line and the signal line connected to the pin having the pin number 14 are connected to the CEC line and the signal line connected to the pin having the pin number 14 so that the differential signal can be transmitted. The differential twisted pair is connected and shielded, and is grounded to the CEC line connected to the 17th pin and the DDC ground line.

  Furthermore, a signal line for transmitting an SDA (Serial Data) signal such as E-EDID is connected to a pin having a pin number of 16 and is an SCL (Serial Clock) which is a clock signal used for synchronization during transmission and reception of the SDA signal. ) A signal line through which a signal is transmitted is connected to a pin having a pin number of 15.

  In addition, the signal line through which the SDA signal is transmitted and the signal line through which the SCL signal is transmitted can transmit differential signals in the same manner as the signal line connected to the CEC line and the pin whose pin number is 14. In this way, the differential twisted pair is connected and shielded, and is grounded to the ground line connected to the 17th pin.

  Further, a signal line for transmitting a signal for detecting connection of a new electronic device is connected to a pin having a pin number of 19.

  FIG. 3 shows a pin arrangement of a connector called HDMI type-B (Type-B).

  In this pin arrangement, TMDS DATA # i (5+, 5-, 4+, 4-, 3+, 3-) and their shielding pins are assigned to pins with pin numbers 13 to 21, and in the arrangement of FIG. The pin numbers of CEC to Hot Plug Detcet assigned to pins 12 to 19 are shifted and assigned to pins 22 to 29.

As described above, the HDMI connector has 19 pins for type A and 29 pins for type B that can be connected.
As shown in FIG. 1, the signal line + 5V Power connected to the pins of the connector pin numbers 18 and 28 is driven from the transmitter 110 side, and the signal line Hot Plug Detect connected to the pins of the pin numbers 19 and 29 is connected. A voltage is supplied from the receiver 120 side to the signal lines TMDS Data Line connected to the pins with pin numbers 1 to 12 and 1 to 21.

Although only one set is shown in a simplified manner in FIG. 1, there are actually three sets of TMDS Data Line in one HDMI cable 130.
Further, EDID (Extended Display Identification Data) indicates information about a display established by VESA (Video Electronics Standards Association). Since the display is on the receiver side in HDMI, the transmitter side reads and uses the data on the receiver side when connecting.

  The transmitter 110 and the receiver 120 according to the present embodiment include the + 5V Power signal line 131 as the first signal line, and either the Hot Plug Detect signal line 132 or the TMDS Data Line signal line 133 as the second signal line. A function of monitoring one voltage and determining whether the connected device is a transmitter or a receiver (device discrimination function).

In addition, when the transmitter 110 and the receiver 120 of this embodiment are a transmitter and the connection partner is not a receiver, the transmitter 110 and the receiver 120 notify the user that the connection partner is not a receiver through a display panel, a display lamp, audio output, or the like. And a function for prompting the user to confirm the connection (notification function).
Further, when the transmitter 110 and the receiver 120 are receivers and the connection partner is not a transmitter, the transmitter 110 and the receiver 120 notify the user that the connection partner is not a transmitter through a screen display, a display panel, a display lamp, audio output, etc. It has a function (notification function) that prompts the user to confirm the connection.
That is, the transmitter 110 and the receiver 120 of the present embodiment have a function of determining whether the connection partner device is a transmitter or a receiver, and a notification function that alerts the user when the connection partner is erroneously connected. In order to avoid destruction of equipment when receivers and transmitters are connected to each other, it has a function of retaining connections (reservation function).

Further, the transmitter 110 intermittently applies a voltage to the + 5V Power signal line 131 as the first signal line in order to correctly start communication, and thus starts communication when the own device is identified as the transmitter. Function (+ 5V Power signal line voltage control function).
In this case, the transmitter 110 increases the possibility that the own device is identified as a transmitter by changing the interval of the voltage intermittently applied to the + 5V Power signal line 131 in order to start communication correctly. (+ 5V Power signal line voltage control function).

Further, the receiver 120 may be interposed between some or all of the Hot Plug Detect signal line 132 as the second signal line and the TMDS Data Line signal line 133 as the second signal line in order to correctly start communication. It has a function (Hot Plug Detect signal line 132 or TMDS Data Line signal line voltage control function) that can start communication by applying a voltage continually and determining that the device is a receiver.
In this case, the receiver 120 changes the interval of the voltage applied intermittently to some or all of the Hot Plug Detect signal line 132 and the TMDS Data Line signal line 133 in order to start communication correctly. In addition, it has a function (Hot Plug Detect signal line 132 or TMDS Data Line signal line voltage control function) that can increase the possibility that the device is identified as a receiver and start communication.

  Further, the transmitter 110 and the receiver 120 disconnect the cable by dropping a part or all of the voltages of the + 5V Power signal line 131, the Hot Plug Detect signal line 132, and the TMDS Data Line signal line 133 of the HDMI connector units 111 and 1121. It has a function (connection re-establishment function) that re-establishes the connection with the counterpart device by generating the same effect as the above, and then reconnecting again.

The transmitter 110 of the present embodiment includes a detection control unit 113 and a notification unit 114 that express each of the functions described above.
Similarly, the receiver 120 of this embodiment includes a detection control unit 123 and a notification unit 124 that express each of the functions described above.

  The detection control unit 113 of the transmitter 110 has a function of supplying + 5V power held in the range of 4.8 to 5.3V to the + 5V Power signal line 131 via the resistance element R111.

The detection control unit 123 of the receiver 120 has a function of supplying a voltage held in the range of 2.4 to 5.3 V to the Hot Plug Detect signal line 132 via the resistance element R121.
The detection control unit 123 of the receiver 120 has a function of pulling up the differential TMDS Data Line signal line 133 to the voltage AVcc (3.3 V) via the resistance elements R122 and R123.

  FIG. 4 is a diagram illustrating a configuration example of a detection system of the detection control unit in the transmitter according to the present embodiment.

  The detection control unit 113 includes a switch 1131 connected between one end of the resistance element R111 and the + 5V Power signal line 131, a detection buffer 1132 having an input connected to the + 5V Power signal line 131, and an input. A detection buffer 1133 connected to the Hot Plug Detect signal line 132, a detection buffer 1134 connected to one signal line 133-1 of the differential TMDS Data Line signal line 133, and a differential TMDS Data input A detection buffer 1135 connected to one signal line 133-1 of the Line signal line 133.

  FIG. 5 is a diagram illustrating a configuration example of a detection system of the detection control unit in the receiver according to the present embodiment.

  The detection system of the detection control unit 123 includes a switch 1231 connected between one end of the resistance element R121 and the Hot Plug Detect signal line 132, one end of the resistance element R122, and one signal line 133- of the TMDS Data Line signal line 133. 1, a switch 1232 connected between 1, a switch 1233 connected between one end of the resistance element R 123 and the other signal line 133-2 of the TMDS Data Line signal line 133, and an input connected to the + 5V Power signal line 131. Detection buffer 1134, a detection buffer 1235 whose input is connected to the Hot Plug Detect signal line 132, and a detection buffer 1236 whose input is connected to one signal line 133-1 of the differential TMDS Data Line signal line 133 And a detection buffer 1237 connected to one signal line 133-1 of the TMDS Data Line signal line 133 whose input is differential.

  Hereinafter, the device discrimination function of the transmitter 110 and the receiver 120 according to the present embodiment, the discrimination result notification function, and various control functions in 113 and 123 in the detection control unit will be specifically described.

  First, the device discrimination function will be described.

The detection controllers 113 and 123 monitor the voltage of the + 5V Power signal line 131 of the HDMI connector and any one of the Hot Plug Detect signal line 132 and the TMDS Data Line signal line 133.
When a transmitter is connected as a connection partner, a voltage of +5 V is applied to the +5 V Power signal line 131.
Therefore, if a voltage of a certain level or higher is detected on the + 5V Power signal line 131, it can be determined that the connection partner is a transmitter.

When a receiver is connected as a connection partner, a voltage of 2.4V to 5.3V is detected on the Hot Plug Detect signal line 132, and the TMDS Data Line signal line 133 is pulled up to + 3.3V.
Therefore, if a voltage of a certain level or more is detected in any one of the Hot Plug Detect signal line 132 and the TMDS Data Line signal line 133, it can be determined that the connection partner is the receiver.

  If both the + 5V Power signal line 131 and the Hot Plug Detect signal line 132 or the TMDS Data Line signal line 133 cannot detect the voltage, the connectors 111 and 121 are either not connected to the cable or are connected to each other. Since both sides are powered off, it is possible to detect when the other party is powered on by continuously monitoring both sides.

When such a device discrimination function is realized on the transmitter 110 side, a configuration as shown in FIG. 4 can be adopted.
The detection control unit 113 opens the switch 1131 at the time of detection, and determines that the connection partner is a transmitter when the detection buffer 1132 detects a high (Hi: + 5V) state.
When the detection control unit 113 detects a high (Hi: 2.4 to 5 V, 3.3 V) state in any of the detection buffers 1133, 1134, and 1135, the detection control unit 113 determines that the connection partner is a receiver.

Similarly, when the device discrimination function is realized on the receiver 120 side, a configuration as shown in FIG. 5 can be adopted.
The detection control unit 123 opens all three switches 1231 to 1233 at the time of detection, and determines that the connection partner is a transmitter when the detection buffer 1134 detects a high (Hi: + 5V) state.
When the detection control unit 123 detects a high (Hi: 2.4 to 5 V, 3.3 V) state in any of the detection buffers 1235, 1236, and 1237, the detection control unit 123 determines that the connection partner is a receiver.

  Next, the notification function will be described.

The transmitter 110 and the receiver 120 perform the following processing using the result of the automatic detection and discrimination by the above-described device detection function.
If the transmitter itself is a transmitter, the detection control unit 113 notifies the user that the connection partner is not a receiver through a display panel, a display lamp, audio output, or the like that forms the notification unit 114 (notification) when the connection partner is not a receiver. ) To prompt the user to confirm the connection.
When the receiver itself is a receiver, the detection control unit 123 notifies the user that the connection partner is not a transmitter through a display panel, a display lamp, an audio output, or the like that forms the notification unit 124 when the connection partner is not a transmitter. Prompt for confirmation of connection.

  Next, the reservation function will be described.

Further, the transmitter 110 and the receiver 120 perform the following processes using the results of the automatic detection and determination by the above-described device detection function.
When the transmitter itself is a transmitter, for example, the connector unit 111 employs a configuration as shown in FIG. 6 and switches SW11 to SW1n provided at the connection portion between the Hot Plug Detect signal line 132 and the TMDS Data Line signal line 133 are connected to the device. Until all of the signal lines or some of the signal lines with a high possibility of failure are opened until the counterpart device is detected as a receiver by the detection function, the switches SW11 to SW11 are not connected until the connected counterpart device is detected as the receiver. A failure of the device is avoided by connecting each signal line with the HDMI connector unit 111 with the SW1n closed.

  When the receiver itself is a receiver, for example, a configuration as shown in FIG. 7 is adopted for the connector portion 121 and provided at the connection portion with the + 5V Power signal line 131, the Hot Plug Detect signal line 132, and the TMDS Data Line signal line 133. Leave all the signal lines or some of the signal lines with a high possibility of failure until the switches SW21 to SW2n are detected as a transmitter by the device detection function, and the connected device detects it as a transmitter. For the first time, the switches SW21 to SW2n are closed and the signal lines are connected by the HDMI connector unit 121, thereby avoiding the failure of the device.

  Next, the + 5V Power signal line voltage control function will be described.

In the transmitter 110 having the device discrimination function, the following processing is performed in order.
The detection control unit 113 intermittently considers the case where no voltage is applied to any of the monitored signal lines, and the other party is also a device having a device discrimination function, and intermittently + 5V to the + 5V Power signal line 131. The connection partner device is recognized by intermittently applying the voltage.
If the connection partner has a device discrimination function and a receiver function, the connection is established as the receiver.
Since the detection control unit 113 does not know when the other party's power is turned on or when the cable is connected, it is necessary to repeatedly perform intermittent voltage application processing.

8A to 8C are timing charts of a recognition operation by applying an intermittent voltage between transmitters.
In this case, the period T1 during which the voltage is applied needs to be longer than the time necessary for the partner to recognize itself as a transmitter and to start the operation as the receiver.
By determining and standardizing the voltage application period T1 within a range that can be guaranteed in terms of design by the transmitter and receiver devices, connections between various devices can be made possible.
The voltage application interval (period in which no voltage is applied) T2 is arbitrary, and may be the same interval or a different interval each time.

Furthermore, it is possible to prevent the next timing from overlapping even if a signal collides once (collision) by starting recognition operations by randomly changing the period T2 during which no voltage is applied. It is.
According to the standard, an HDMI device is required not to be destroyed even when receivers and transmitters are connected to each other.

  Next, the Hot Plug Detect signal line 132 or the TMDS Data Line signal line voltage control function will be described.

In the receiver 120 having the device discrimination function, the following processing is performed in order.
The detection control unit 123 intermittently considers the Hot Plug Detect signal line 132 or the TMDS in consideration of the case where no voltage is applied to any of the monitored signal lines, and the other party is also a device having a device discrimination function. A necessary voltage is intermittently applied to a part or all of the Data Line signal line 133 to recognize the connected device.
If the connection partner has a device discrimination function and has a transmitter function, the partner side establishes a connection as a transmitter.
Since the detection control unit 123 does not know when the power of the counterpart is turned on or when the cable is connected, it is necessary to repeatedly perform intermittent voltage application processing.

9A to 9C are timing charts of the recognition operation by applying the intermittent voltage between the receivers.
In this case, the period T3 during which the voltage is applied needs to be longer than the time necessary for the partner to recognize itself as a receiver and to start the operation of the partner as a transmitter.
By determining and standardizing the voltage application period T3 within a range that can be guaranteed in terms of design by the transmitter and receiver devices, it is possible to enable connection between various devices.
The voltage application interval (period in which no voltage is applied) T4 is arbitrary, and may be the same interval or a different interval each time.

Furthermore, it is possible to prevent the next timing from overlapping even if the signals collide once (collision) by starting the recognition operation with each other by randomly changing the period T4 during which no voltage is applied. It is.
According to the standard, an HDMI device is required not to be destroyed even when receivers and transmitters are connected to each other.

Next, the connection re-establishment function will be described.
In the present embodiment, the following functions are realized in the HDMI connector units 111 and 121.
If the device is in a connected state as a transmitter, the disconnected state is created by dropping the voltage of the + 5V Power signal line 131.
If the device is in the connected state as a receiver, the disconnected state is created by dropping the voltage of the Hot Plug Detect signal line 132 and the TMDS Data Line signal line.
As described above, in the transmitter 110 or the receiver 120, a part or all of the voltages of the + 5V Power signal line 131, the Hot Plug Detect signal line 132, and the TMDS Data Line signal line 133 of the HDMI connector units 111 and 121 are dropped. The same effect as that of unplugging the cable is generated, and then it is possible to reestablish the connection with the counterpart device by reconnecting again.

In the above, as an embodiment, the case where an electronic device having a transmitter function and an electronic device having a receiver function are connected by a communication cable has been described.
Hereinafter, as another embodiment, a case where an electronic device having both functions of a transmitter and a receiver is described using a communication cable will be described.

  FIG. 10 is a diagram illustrating a configuration example of a main part of an electronic apparatus having functions of both a transmitter and a receiver according to another embodiment of the present invention.

  The electronic device 150 includes an HDMI connector unit 151 as a connection unit to which the HDMI cable 130 is connected.

  The electronic device 150 converts, for example, pixel data of an uncompressed image into a corresponding differential signal, and is connected via the HDMI cable 130 with three TMDS channels # 0, # 1, and # 2 that are a plurality of channels. The receiver 120 (HDMI sink) has a signal transmission unit 112 for serial transmission in one direction.

  In addition, the electronic device 150 transmits a differential signal corresponding to pixel data transmitted in one direction from the transmitter 110 connected via the HDMI cable 130 via the TMDS channels # 0, # 1, and # 2. A receiving unit 153 that receives differential signals corresponding to audio data and control data in synchronization with a pixel clock transmitted from the transmitter 110 via the TMDS clock channel is also provided.

  As shown in FIG. 10, the detection system of the detection control unit 154 of the electronic device 150 includes a switch 1541 connected between one end of the resistance element R151 and the + 5V Power signal line 131, one end of the resistance element R152, and Hot. Switch 1542 connected between Plug Detect signal line 132, one end of resistance element R153 and switch 1543 connected between one signal line 133-1 of TMDS Data Line signal line 133, one end of resistance element R153, and TMDS A switch 1544 connected between the other signal lines 133-2 of the Data Line signal line 133, a detection buffer 1545 whose input is connected to the + 5V Power signal line 131, and an input which is connected to the Hot Plug Detect signal line 132 Detection buffer 1546, a detection buffer 1547 connected to one signal line 133-1 of a differential TMDS Data Line signal line 133, and a differential TMDS input. And a detection buffer 1548 connected to one signal line 133-2 of the Data Line signal line 133.

The electronic device 150 basically has the above-described device discrimination function, notification function, reservation function, + 5V Power signal line voltage control function, Hot Plug Detect signal line 132 or TMDS Data Line signal line voltage control function, and connection Has a re-establishment function.
Hereinafter, characteristic functions of an electronic device having both functions of a transmitter and a receiver will be described.

  In the electronic device 150 having both functions of a transmitter and a receiver, the following processing is performed depending on whether the connection partner is a transmitter or a receiver, using the result automatically detected and determined by the device determination function. .

When the connection partner is detected as a receiver, the connection is made by acting as a transmitter.
When the connection partner is detected as a transmitter, the connection is made by acting as a receiver.
As described above, the electronic device 150 has a function of automatically switching whether the device operates as a receiver or a transmitter based on the detected information.
Thereby, the function of the HDMI connector is switched, and the function as a receiver is used for the entire device. For example, the video camera behaves as a display device or a recording / recording device in a home video camera, or the function as a transmitter is used. It is possible to switch whether the camera behaves as a playback device.
If the above functions are realized, a circuit configuration as shown in FIG. 10 can be adopted.

The detection control unit 154 opens the switches 1541 to 1544 at the time of detection, short-circuits the switch 1541 and opens the switches 1542 to 1544 when operating as a transmitter.
The detection control unit 154 short-circuits the switches 1542 to 1544 and opens the switch 1541 when operating as a receiver.
The detection control unit 154 is used for data transmission when the switches 1542 to 1544 function as a transmitter, and remains open when functioning as a receiver.

  Next, the voltage control function of the electronic device 150 will be described.

In the electronic device 150 having both functions of a transmitter and a receiver, the following processing is performed in order.
If no voltage is applied to any of the monitored signal lines, the Hot Plug Detect signal line 132 or the TMDS Data Line signal line 133 is intermittently taken into consideration when the other party is also a device having a device discrimination function. Apply the voltage required for some or all of them intermittently.
If the connection partner has a device discrimination function and has a transmitter function, the partner side establishes a connection as a transmitter.

Considering the case where the other party is also a device having a device discrimination function, a voltage of +5 V is intermittently applied to the +5 V Power signal line 131 intermittently.
If the connection partner has a device discrimination function and a receiver function, the connection is established as the receiver.
Since the detection control unit 154 does not know when the other party's power is turned on or when the cable is connected, it is necessary to repeatedly perform intermittent voltage application processing.

FIGS. 11A to 11C are timing charts of a recognition operation by applying an intermittent voltage when both functions of a transmitter and a receiver are provided.
The periods T11 and T12 during which the voltage is applied must be longer than the time required for the partner to recognize itself as a receiver or transmitter, and for the partner to start operating as a transmitter or receiver.
By determining and standardizing the voltage application periods T1 and T2 within a range that can be guaranteed in terms of design by the transmitter and receiver devices, it is possible to enable connection between various devices.
The voltage application intervals (periods during which no voltage is applied) T13 and T14 are arbitrary, and may be the same interval or different intervals each time.

Further, by starting the recognition operation with each other by randomly changing the periods T13 and R14 in which no voltage is applied, the next timing does not overlap even if the signals collide once (even if they collide). Is also possible.
According to the standard, an HDMI device is required not to be destroyed even when receivers and transmitters are connected to each other.

The electronic device 150 having both functions of a transmitter and a receiver further has the following functions.
The electronic device 150 has a function of automatically switching depending on a connection partner whether the user operates as a receiver or a transmitter by a user interface.
When the user designates to operate as a receiver, the connector section operates in the same manner as a standard receiver connector.
When the user designates to operate as a transmitter, the connector portion performs the same operation as the connector portion of a standard transmitter.
When the user designates automatic switching according to the connection partner, as described above, based on the detected information, the device automatically switches whether the device operates as a receiver or a transmitter.

If the setting is changed during connection establishment and is different from the connection state, a warning may be displayed to the user to prompt the user to turn on / off the power.
If the setting is changed during connection establishment and is different from the connection state, a warning may be displayed to the user, and the power may be turned on and off automatically.
If the setting is changed during connection establishment and is different from the connection state, the connection may be once canceled and connection establishment may be attempted again.

The electronic device 150 having both functions of a transmitter and a receiver further performs the following processing.
While the connection is established, the detection control unit 154 detects that the communication cable 130 has been disconnected or the connection partner has been turned off by monitoring the signal line using the device discrimination function.
When the communication cable is disconnected or the connection partner is detected as being powered off, the detection control unit 154 interrupts the processing of the receiver and transmitter, and returns to the connection partner detection waiting state in the device discrimination function.
When the connection is reconnected, the detection control unit 154 detects the connection partner regardless of the state connected immediately before and establishes the connection.

The electronic device 150 having both functions of a transmitter and a receiver further performs the following processing.
An electronic device having both functions of a transmitter and a receiver and having a Hot Plug Detect signal line 132 or a TMDS Data Line signal line voltage control function is connected by a communication cable to establish a connection.
The transmitter obtains the EDID from the receiver, and determines from the EDID whether the connectors of both the transmitter and receiver compatible electronic devices are connected.
When the connectors of both transmitter and receiver compatible electronic devices are connected, it is unclear which side is the transmitter or the user expects.
Therefore, the transmitter side displays on the notification unit 155 that the connector of the electronic device corresponding to both transmitter and receiver is connected by the communication cable 130 to prompt the user to select.
When the user selects the receiver function, since it is different from the current connection state, the connection is cut off by changing the intermittent voltage at random, and the connection is made again according to the setting.

According to this embodiment described above, the following effects can be obtained.
Currently, an HDMI terminal is used in some home CE devices such as television receivers and DVDs. As shown in FIG. 12, the HDMI terminal connects a receiver 201 that is a television receiver and a transmitter 202 that is a DVD facing each other.
In the future, it is difficult to increase the number of terminals. As shown in FIG. 13, there is a concern about a problem due to erroneous connection when a transmitter 202 as a DVD and a DVD 203 as a transmitter are connected.
However, in the case of incorrect connection, the user can only know that the device does not operate normally. There are various causes for malfunctions, such as incomplete settings and device failures, but by recognizing the incorrect cable connection and notifying the user, the user may recognize that the device will not operate normally due to the incorrect connection. It is possible to improve user convenience and lower support costs of manufacturers.
Similarly, destruction due to erroneous connection is assumed, but the risk of destruction can be reduced by starting the connection process after detecting the partner.
When a recording device such as a home video camera or personal computer and a playback device are integrated, as shown in FIGS. 14A and 14B, both the receiver function and the transmitter function are to be realized. Exists.
In that case, it is assumed that two HDMI connectors are currently attached, or an HDMI connector whose function can be switched by a changeover switch.

As in this embodiment, by installing an HDMI connector that is automatically switched between the receiver function and transmitter function on the device, the connector installation space is reduced, the manufacturing cost is reduced, and there is only one connector. Can be reduced and user convenience can be improved.
If the connection is detected after the connection is detected according to the present embodiment, a signal is not output when devices having similar functions are connected to each other, and thus the connection cannot be detected.
Therefore, by applying voltage intermittently, connection can be started even when connectors having similar functions are connected.
As a result, the connection can be started even when the devices are connected to each other after the spread of the devices having the function of connecting after detecting the connection.

In addition, as shown in FIG. 15, when devices that can be transmitters and receivers are connected to each other, it is impossible for one side to be a transmitter and the other side to be a receiver as desired by the user. The user can select it.
This eliminates the need for the user to make settings prior to connection and improves convenience. In addition, the user does not perform the intended operation by specifying which is the transmitter, making the operation intuitive. Is expected to be.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

It is a figure which shows the structural example of the principal part of the communication system which concerns on one Embodiment of this invention. It is a figure which shows the pin arrangement of the connector called HDMI type A (Type-A). It is a figure which shows the pin arrangement of the connector called HDMI type B (Type-B). It is a figure which shows one structural example of the detection system of the detection control part in the transmitter which concerns on this embodiment. It is a figure which shows one structural example of the detection system of the detection control part in the receiver which concerns on this embodiment. It is a figure which shows the structural example of the transmitter side connector part with a destruction prevention function. It is a figure which shows the structural example of the receiver side connector part with a destruction prevention function. It is a timing chart of the recognition operation | movement by the intermittent voltage application of a transmitter. It is a timing chart of the recognition operation | movement by the intermittent voltage application of a receiver. It is a figure which shows the structural example of the principal part of the electronic device which has the function of both the transmitter and receiver which concern on other embodiment of this invention. It is a timing chart of recognition operation by applying an intermittent voltage between the functions of both a transmitter and a receiver. It is a figure which shows the normal connection state of electronic devices. It is a figure which shows the misconnection state of electronic devices. It is a figure which shows the example of a connection in case the same apparatus has a receiver function and a transmitter function. It is a figure which shows the example of a connection of the apparatuses which can become a receiver and a transmitter.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Communication system, 101, 102 ... Electronic device, 110 ... Transmitter, 111 ... HDMI connector part, 112 ... Signal transmission part, 113 ... Detection control part, 114 ... Informing unit, 120 ... receiver, 121 ... HDMI connector unit, 122 ... receiving unit, 123 ... detection control unit, 124 ... informing unit, 130 ... communication cable, 131 ... + 5V Power signal line (first signal line), 132... Hot Plug Detect signal line (second signal line), 133... TMDS Data Line signal line (second signal line), 150.・ Electronic device having both transmitter and receiver functions, 151... HDMI connector unit, 152... Signal transmission unit, 153... Reception unit, 154. .

Claims (16)

A communication unit between electronic devices that includes a connector portion to which a communication cable can be connected, and is capable of transmitting video and audio data, exchanging information on connected devices, and communicating device control data. There,
The electronic device
It can have at least one of transmitter function and receiver function,
The communication cable is
A first signal line driven to a predetermined voltage by a transmitter;
A second signal line driven to a predetermined voltage by the receiver,
The electronic device
A detection control unit configured to detect the voltage of the first signal line or the voltage of the second signal line connectable to the connector unit and determine whether the connection-side electronic device is a receiver or a transmitter; Communications system. Including a connector portion to which a communication cable can be connected, and the communication cable is capable of transmitting video and audio data, exchanging information on connected devices, and communicating device control data with a single cable. An electronic device capable of having at least one of the functions of a receiver,
The communication cable is
A first signal line driven to a predetermined voltage by a transmitter;
A second signal line driven to a predetermined voltage by the receiver,
The electronic device
A detection control unit configured to detect the voltage of the first signal line or the voltage of the second signal line connectable to the connector unit and determine whether the connection-side electronic device is a receiver or a transmitter; Electronics. Having a notification unit having a notification function;
The detection control unit
3. When it is determined that the device is a transmitter and the connection partner is not a receiver, or when it is determined that the device is a receiver and the connection partner is not a transmitter, the notification unit notifies that the connection is incorrect. The electronic device described. The detection control unit
The electronic device according to claim 2, wherein the electronic device has a function of reserving connection when it is determined that the receivers or the transmitters are connected in the determination process. The detection control unit
The electronic device according to claim 2, wherein the electronic device has a function of automatically switching whether the device operates as a receiver or a transmitter based on the detected and determined information. The detection control unit
When the own device functions as a transmitter, communication can be started when the own device is identified as a transmitter by applying a voltage intermittently to the first signal line in order to correctly start communication. The electronic device according to claim 2 having a function. The detection control unit
7. The function of starting communication by increasing a possibility that the device is identified as a transmitter by randomly changing an interval between voltages applied intermittently to the first signal line. Electronic equipment. The detection control unit
When the own device functions as a receiver, in order to start communication correctly, voltage can be intermittently applied to the second signal line, so that the own device is identified as a receiver and communication can be started. The electronic device according to claim 2 having a function. The detection control unit
The function of starting communication by increasing the possibility that the device is discriminated as a receiver by randomly changing the interval of the voltage applied intermittently to the second signal line. Electronic equipment. The detection control unit
When the own device functions as a receiver or a transmitter, in order to start communication correctly, a voltage is intermittently applied to the second signal line or the first signal line, so that the own device The electronic device according to claim 5, wherein the electronic device has a function of starting communication by being identified as a transmitter. The detection control unit
By randomly changing the interval of the voltage applied intermittently to the second signal line or the first signal line, it is possible to increase the possibility that the device is discriminated as a receiver or transmitter and start communication. The electronic device according to claim 10, wherein the electronic device has a function capable of. The detection control unit
When the voltage of at least one of the first signal line and the second signal line is dropped, the same state as the state in which the cable is disconnected is generated, and then reconnected again to connect to the connection counterpart device. The electronic device according to claim 2, having a function of re-establishing. The detection control unit
The electronic apparatus according to claim 5, wherein the electronic device has an operation mode in which the automatic switching is temporarily disabled by determining in advance whether the receiver or the transmitter is to be operated. The detection control unit
The electronic device according to claim 5, wherein the electronic device has a function of detecting whether the communication cable is inserted or removed or turning off the power and returning to the state before the detection again even after the automatic switching. The detection control unit
When the own device functions as a receiver, in order to start communication correctly, voltage can be intermittently applied to the second signal line, so that the own device is identified as a receiver and communication can be started. It has a function to exchange device information using EDID (Extended Display Identification Data) after connection, and automatically switches whether the device operates as a receiver or transmitter based on the detected and identified information The electronic device according to claim 5, which has a function of reselecting which one is a transmitter when it is found that the devices have functions. A communication unit that can connect a communication cable, and the communication cable is a communication method between electronic devices capable of transmitting video and audio data, exchanging connected device information, and communicating device control data. There,
The electronic device
It can have at least one of transmitter function and receiver function,
The communication cable is
A first signal line driven to a predetermined voltage by a transmitter;
A second signal line driven to a predetermined voltage by the receiver,
The voltage of the first signal line or the voltage of the second signal line that can be connected to the connector portion is detected, and it is possible to determine whether the connection-side electronic device is a receiver or a transmitter, and communication is possible. Communication method to determine whether.

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