JP5943439B2 - Electronic device, communication system, and hot plug control method - Google Patents

Description

  The present invention relates to a technique for causing an external device to detect a connection with an electronic device in a communication system in which the external device is connected to the electronic device via a signal cable.

  In a communication system in which an external device and an electronic device are connected via a signal cable, the electronic device receives a voltage from the external device and outputs a signal indicating the connection with the external device. As this type of electronic device, for example, an HDMI device having an interface conforming to the HDMI (High-Definition Multimedia Interface) standard is known.

  HDMI is a standard for a communication interface that transmits video / audio as a digital signal. Recently, various devices having an interface conforming to the HDMI standard have been provided.

  The HDMI standard communication system includes a source device that sends out an HDMI signal and a sink device that receives the HDMI signal. The source device and the sink device are connected via an HDMI cable (see Patent Document 1).

  The source device is, for example, a Blu-ray disc player, a video camera, a portable device, or the like. The sink device is, for example, a monitor or projector such as an HD (High Definition) television.

  In the communication system, when the source device and the sink device are connected by an HDMI cable, processing for transmitting an HDMI signal between the source device and the sink device is executed.

  FIG. 1 shows an example of an HDMI signal transmission / reception sequence.

  Referring to FIG. 1, first, the source device supplies a predetermined voltage (for example, + 5V) to the sink device (step S100), and the sink device receives the voltage supply and sends the hot plug detection signal to the source device. Transmit (step S101).

  The source device recognizes that the sink device is connected to its own device based on the hot plug detection signal from the sink device.

  The source device that has received the hot plug detection signal accesses EDID (Extended Display Identification Data) information in the sink device (step S102), and the sink device sends the EDID information held by itself to the source device (step S102). S103). Here, the EDID information is a data set indicating information on functions and performance (specifically, format, resolution, etc.) supported by the sink device.

  Based on the EDID information acquired from the sink device, the source device recognizes the video / audio format and resolution that can be played back by the sink device, and converts the video / audio signal corresponding to the format / resolution to TMDS (Transition Minimized Differential Signaling). ) Is transmitted to the sink device by a transmission method called ().

  The sink device receives the TMDS signal from the source device (step S105). In addition to the TMDS signal, a clock signal and a control signal are also supplied from the source device to the sink device. The sink device performs processing such as reproduction of the TMDS signal based on the clock signal in accordance with the control signal.

  FIG. 2 shows a configuration example of the sink device.

  Referring to FIG. 2, the sink device includes an HDMI connector 101, a memory 102, and an HDMI receiver IC (Integrated circuit) 103.

  The memory 102 is a nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read-Only Memory), and holds EDID information.

  The HDMI connector 101 is a 19-pin standard type connector. The 19th pin is a pin for outputting a hot plug detection signal. A voltage of +5 V is supplied to the 18th pin from the source device.

  The 18th pin is connected to the 19th pin via a resistance element. When a voltage of +5 V is supplied to the 18th pin, a current flows through the resistance element, and the hot plug is connected to the 19th pin. A detection signal (+ 5V signal) is output.

  The 15th pin and the 16th pin are pins for reading EDID information stored in the memory 102. These numbers 15 and 16 are each connected to the memory 102 and also to the HDMI receiver IC 103.

  Some of the remaining pins receive TMDS signals, clock signals, and control signals from the source device. The HDMI receiver IC 103 performs a TMDS signal reproduction process based on the clock signal in accordance with the control signal.

  FIG. 3 shows another configuration example of the sink device.

  The sink device shown in FIG. 3 is configured such that the memory 102 is removed from the sink device shown in FIG. 2 and the HDMI receiver IC 103 holds the EDID information 104.

  In the sink device shown in FIG. 3, the HDMI receiver IC 103 accepts access from the source device via the 15th and 16th pins, and outputs the EDID information 104 held by itself from the 15th and 16th pins. To do. Other operations are the same as those shown in FIG.

  2 and FIG. 3, the + 5V hot plug detection signal is supplied when a + 5V voltage is supplied to the 18th pin, regardless of whether or not the own device is powered on. Is output from the 19th pin.

JP 2011-239386 A

  As described above, both of the sink devices shown in FIGS. 2 and 3 output a + 5V hot plug detection signal to the source device when a + 5V voltage is supplied from the source device even when the power is OFF. It is configured. On the other hand, the source device does not have a function of detecting whether or not the sink device connected to the source device is turned on. For this reason, the sink device shown in FIGS. 2 and 3 has the following problems when connected to the source device in the power-off state. Here, the power OFF state is not a standby state (so-called standby state) but a state where the sink device is not connected to a commercial AC power source.

  First, a problem that occurs when the sink device shown in FIG. 2 is connected to the source device in a power-off state will be described.

  The source device receives the + 5V hot plug detection signal from the sink device in the power-off state, and reads the EDID information from the memory 102 in the sink device. In the sink device shown in FIG. 2, since the EDID information is stored in the memory 102 which is a non-volatile memory, the source device can read the EDID information from the memory 102 even when the sink device is not turned on. it can.

  When the source device acquires EDID information from the sink device in the power-off state, the source device supplies the TMDS signal to the sink device in the power-off state. When the TMDS signal is supplied to the sink device in the power-off state, a current leaks to the circuit of the sink device, and as a result, the sink device may malfunction.

  Normally, the HDMI receiver IC 103 has a malfunction prevention function. When the sink device is powered on, the malfunction due to the leakage current does not occur due to the malfunction prevention function. However, when the sink device is not powered as described above, the malfunction prevention function does not work, and malfunction due to leakage current becomes serious.

  Next, a problem that occurs when the sink device shown in FIG. 3 is connected to the source device with the power off is described.

  The source device receives the + 5V hot plug detection signal from the sink device in the power-off state, and accesses the EDID information 104 in the sink device. In the sink device shown in FIG. 3, since the EDID information 104 is held in the HDMI receiver IC 103, the source device cannot access the HDMI receiver IC 103 when the power of the sink device is not turned on. Information 104 cannot be acquired.

  If the source device cannot acquire the EDID information, the source device cannot recognize the function and performance (format and resolution) of the sink device, and therefore does not supply the TMDS signal to the sink device.

  As described above, when the source device cannot acquire the EDID information after receiving the + 5V hot plug detection signal, the TMDS signal is not supplied to the sink device. However, the video cannot be displayed on the sink device.

  For example, when the source device and the sink device are connected via an HDMI cable and the source device is turned on and then the sink device is turned on, the source device is connected to the sink device as described above. In some cases, EDID information cannot be acquired, and a video cannot be displayed on the sink device.

  Note that the above-described problems such as malfunction and failure to display video occur even when the sink device is connected to a commercial AC power source and the HDMI receiver IC 103 or the communication unit of the HDMI receiver IC 103 is not activated. Here, the communication unit is a part that receives a signal from the source device via the HDMI connector 101.

  An object of the present invention is to provide an electronic device, a communication system, and a hot plug control method that can solve the above-described problems such as malfunction and failure to display an image.

In order to achieve the above object, according to one aspect of the present invention,
A connector portion connected to an external device via a signal cable, the connector portion having at least first and second pins, and a predetermined voltage from the external device is applied to the first pin; Electronic equipment to be supplied,
A communication unit to which a signal is input from the external device via a pin other than the first and second pins of the connector unit, and when the communication unit is activated, A control unit that outputs a signal of 1;
An output unit that outputs a first detection signal indicating that there is no connection to the external device to the external device via the second pin when the first signal is not output; An electronic device is provided.

According to yet another aspect of the invention,
A sink device composed of the above electronic devices;
A source device connected to the sink device via a communication cable,
When the source device supplies a predetermined voltage to the sink device and receives a detection signal of the predetermined voltage from the sink device, a communication system is provided that recognizes that the sink device is connected to the own device. .

According to another aspect of the invention,
A connector unit connected to an external device via a signal cable, the connector unit being a hot plug control method performed in an electronic device including at least first and second pins;
A predetermined voltage is applied to the first pin from the external device in a state where a communication unit to which a signal is input from the external device via a pin other than the first and second pins of the connector unit is not activated. When being supplied, the first detection signal indicating that there is no connection with the external device is output to the external device via the second pin,
When the predetermined voltage is supplied from the external device to the first pin in a state where the communication unit is activated, a signal of the predetermined voltage supplied to the first pin is transmitted to the second pin. There is provided a hot plug control method for outputting a detection signal to the external device via the second pin.

It is a figure for demonstrating an example of the HDMI signal transmission / reception sequence performed with the communication system of an HDMI specification. It is a block diagram which shows the example of 1 structure of a sink device. It is a block diagram which shows another structural example of a sink device. It is a block diagram which shows the structure of the HDMI apparatus which is the 1st Embodiment of this invention. FIG. 5 is a schematic diagram for explaining an operation when the HDMI apparatus shown in FIG. 4 is powered off. FIG. 5 is a schematic diagram for explaining an operation when the HDMI apparatus shown in FIG. 4 is powered on. It is a block diagram which shows the structure of the HDMI apparatus which is the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the HDMI apparatus which is the 3rd Embodiment of this invention. FIG. 9 is a schematic diagram for explaining an operation when the HDMI apparatus illustrated in FIG. 8 is powered off. FIG. 9 is a schematic diagram for explaining an operation when the HDMI apparatus illustrated in FIG. 8 is powered on. It is a figure for demonstrating the modification of the HDMI apparatus which is the 3rd Embodiment of this invention. It is a figure for demonstrating the modification of the HDMI apparatus which is the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the HDMI apparatus which is the 4th Embodiment of this invention.

11 HDMI connector 12 Memory 13 HDMI receiver IC
14 switch circuit 15-17 resistance element 18 n-type MOSFET
19 transistor

  The present invention relates to an electronic device connected to an external device via a signal cable, and more particularly to an electronic device that receives a predetermined voltage from the external device and outputs a signal indicating the presence or absence of an electrical connection to the external device to the external device Applies to equipment. More specifically, the present invention is applied to an HDMI apparatus having an interface conforming to the HDMI (High-Definition Multimedia Interface) standard. HDMI is a standard for a communication interface for transmitting video / audio as a digital signal, and is well known in general. Therefore, detailed description thereof is omitted here.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, taking an HDMI device as an example.

(First embodiment)
FIG. 4 is a block diagram showing a configuration of the HDMI apparatus according to the first embodiment of the present invention.

  The HDMI device shown in FIG. 4 is a sink device such as a monitor such as an HD (High Definition) television or a projector, and its main part includes an HDMI connector 11, a memory 12, an HDMI receiver IC 13, and a switch circuit 14.

  The HDMI connector 11 and the memory 12 are the same as the HDMI connector 101 and the memory 102 shown in FIG. As the HDMI connector 11, a connector other than the standard type, for example, a 29-pin connector may be used.

  When the control signal is at the first level (high level), the switch circuit 14 outputs the + 5V voltage signal supplied to the 18th pin from the 19th pin as a hot plug detection signal. Is at the second level (low level or ground potential), a signal having a voltage (low level or ground potential) lower than +5 V is output from the 19th pin as a hot plug detection signal.

  Specifically, the switch circuit 14 includes resistance elements 15 to 17, an n-type MOSFET 18, and a transistor 19.

  The transistor 19 is an NPN transistor, and the emitter is grounded.

  One end of the resistance element 15 is connected to one end of the resistance element 16 and to the 18th pin of the HDMI connector 11. The other end of the resistance element 15 is connected to the drain of the n-type MOSFET 18 and to the 19th pin of the HDMI connector 11. An NPN transistor can be used instead of the n-type MOSFET, but the + 5V voltage signal supplied from the 18th pin has a limitation on the current capacity, so use an n-type MOSFET with less current consumption. Is more convenient.

  The other end of the resistance element 16 is connected to the gate of the n-type MOSFET 18 and to the collector of the transistor 19. The source of the n-type MOSFET 18 is grounded.

  The base of the transistor 19 is connected to the control signal output terminal of the HDMI receiver IC 13 via the resistance element 17.

  The resistance value of the resistance element 15 is 1 kΩ, which is a value according to the HDMI standard. The resistance values of the resistance elements 16 and 17 are both about 10 kΩ.

  The HDMI receiver IC 13 outputs a high-level control signal from the control signal output terminal while the HDMI device is powered on. Except for the above period (when the HDMI device is not powered on), the voltage at the control signal output terminal is at a low level (ground potential). This configuration can be realized by using a switching element such as a MOSFET. Here, the period during which the power is on refers to a period during which the sink device is connected to a commercial AC power source regardless of whether the sink device is performing normal operation or in a standby state.

  Next, the operation of the HDMI device of this embodiment will be described.

  FIG. 5 schematically shows an operation when a +5 V voltage is supplied to the 18th pin of the HDMI connector 11 in the HDMI device in the power-off state.

  As shown in FIG. 5, in the HDMI device in the power-off state, the HDMI receiver IC 13 is not activated, so that a low level control signal is supplied to the base of the transistor 19 via the resistance element 17. As a result, the transistor 19 is turned off.

  When a voltage of +5 V is supplied to the 18th pin of the HDMI connector 11 when the transistor 19 is in the OFF state, a voltage of +5 V is supplied to the gate of the n-type MOSFET 18. Since the threshold voltage of the n-type MOSFET 18 is smaller than + 5V, the n-type MOSFET 18 is turned on.

  When the n-type MOSFET 18 is turned on, the 19th pin is grounded via the n-type MOSFET 18, so that the voltage level of the 19th pin is lowered to a low level. As a result, the hot plug detection signal output from No. 19 becomes low level.

  When the hot plug detection signal is at a low level, the source device does not recognize the HDMI device.

  FIG. 6 schematically shows an operation when a voltage of +5 V is supplied to the 18th pin of the HDMI connector 11 in the HDMI device in the power-on state.

  As shown in FIG. 6, in the HDMI device in the power-on state, the HDMI receiver IC 13 supplies a high level control signal to the base of the transistor 19 via the resistance element 17. As a result, the transistor 19 is turned on.

  When the transistor 19 is turned on, the gate of the n-type MOSFET 18 is grounded through the transistor 19. As a result, the voltage level of the gate of the n-type MOSFET 18 becomes lower than the threshold voltage (low level), and the n-type MOSFET 18 is turned off.

  When the n-type MOSFET 18 is turned off, the 18th pin and the 19th pin are simply connected via the resistance element 15, and a + 5V hot plug detection signal is output from the 19th pin.

  When the source device receives the + 5V hot plug detection signal, the source device recognizes that the HDMI device is connected to the source device. Then, processing based on the procedure of steps S102 to S105 shown in FIG. 1 is performed between the source device and the HDMI device.

  According to the HDMI device of the present embodiment, even when a voltage of +5 V is supplied to the 18th pin of the HDMI connector 11 when connected to the source device with the power off, it is output from the 19th pin. The level of the hot plug detection signal is low. For this reason, the source device does not recognize the connection of the HDMI device in the power OFF state to the own device. Therefore, the TMDS signal is not supplied from the source device to the HDMI device in the power-off state, and the HDMI device does not malfunction due to a leakage current generated by supplying the TMDS signal.

(Second Embodiment)
FIG. 7 is a block diagram showing a configuration of an HDMI apparatus according to the second embodiment of the present invention.

  The HDMI device of this embodiment is configured such that the memory 12 is removed from the HDMI device shown in FIG. 4 and the HDMI receiver IC 13 holds the EDID information 13a.

  In the HDMI device of the present embodiment, the HDMI receiver IC 13 accepts access from the source device via the 15th and 16th pins of the HDMI connector 11, and the EDID information 13a held by itself is stored in the 15th and 16th. Output from the pin. Other operations are the same as those in the first embodiment.

  Similarly to the first embodiment, in the HDMI device of this embodiment, when connected to the source device in a power-off state, even if a voltage of +5 V is supplied to the 18th pin of the HDMI connector 11, 19 The level of the hot plug detection signal output from the pin No. is low. For this reason, the source device does not recognize the connection of the HDMI device in the power OFF state to the own device. Therefore, the source device does not access the HDMI device in the power-off state in order to acquire the EDID information.

  Also in the HDMI apparatus of this embodiment, when the power is turned on, a + 5V hot plug detection signal is output from the 19th pin. Upon receiving this + 5V hot plug detection signal, the source device recognizes the connection of the HDMI device to the device itself, acquires EDID information from the HDMI device, and supplies the TMDS signal to the HDMI device. According to this operation, for example, when the HDMI device is turned on after the source device and the HDMI device in the power-off state are connected by the HDMI cable, the TMDS signal is supplied from the source device to the HDMI device. . Therefore, the video based on the TMDS signal is displayed on the HDMI device.

  The HDMI device of each embodiment described above is an example of the present invention, and changes that can be understood by those skilled in the art may be applied to the configuration and operation thereof without departing from the spirit of the invention.

  For example, in the HDMI device shown in FIGS. 4 and 7, a control unit other than the HDMI receiver IC may supply a control signal to the switch circuit 14. In this case, the control unit may be, for example, a control circuit that controls the operation of the entire sink device.

  Further, the switch circuit 14 is not limited to the illustrated one, and when the control signal is at the first level (high level), the + 5V supplied to the first pin (for example, the 18th pin). Is output from the second pin (for example, the 19th pin) as a hot plug detection signal, and when the control signal is at the second level (low level), a voltage lower than +5 V (low level or ground potential) As long as the signal (2) can be output from the second pin as a hot plug detection signal, any configuration may be used. A mechanical switch such as a relay may be used instead of a semiconductor switch such as a MOSFET or a transistor. At this time, if a latch relay is used, power consumption can be reduced to zero, which is convenient.

(Third embodiment)
FIG. 8 is a block diagram showing a configuration of an HDMI apparatus according to the third embodiment of the present invention.

  The HDMI device shown in FIG. 8 uses a switch circuit 20 instead of the switch circuit 14 of the HDMI device shown in FIG. The HDMI connector 11, the memory 12, and the HDMI receiver IC 13 are the same as those shown in FIG.

  In the HDMI device shown in FIG. 4, the switch circuit 14 has a configuration in which a switch is provided between a second pin (for example, a 19th pin) for hot plug detection and a ground potential. On the other hand, in the present embodiment, the switch circuit 20 includes a switch between a first pin (for example, the 18th pin) that supplies + 5V and a second pin for detecting hot plug (for example, the 19th pin). Is provided.

  The switch circuit 20 includes a resistance element 15 and a switch 21. The switch 21 is a mechanical switch such as a semiconductor switch or a relay. The semiconductor switch can be composed of a transistor, an FET, or a combination thereof.

  When the control signal is at the first level (high level), the switch 21 is turned on, and the 18th pin and the 19th pin are short-circuited via the resistance element 15. In this case, a + 5V voltage signal supplied to the 18th pin is output from the 19th pin as a hot plug detection signal via the resistance element 15. Accordingly, the source device detects that the hot plug detection signal is at a high level, and recognizes the HDMI device that is the sink device.

  On the other hand, when the control signal is at the second level (low level or ground potential), the switch 21 is turned off, and the state between the 18th pin and the 19th pin is released (high impedance state). In this case, since the + 5V voltage signal is not supplied to the 19th pin, the source device does not recognize the HDMI device that is the sink device.

  FIG. 9 shows a state when the HDMI apparatus is powered off. Since the control signal is at the second level (low level), the switch 21 is released. In this case, since the + 5V voltage signal supplied to the 18th pin is not output from the 19th pin as a hot plug detection signal via the resistance element 15, the source device is the sink device HDMI. It does not recognize the device.

  FIG. 10 shows the HDMI device in a power-on state. Since the control signal is at the first level (high level), the switch 21 is short-circuited, and the + 5V voltage signal supplied to the 18th pin is connected to the 19th pin as a hot plug detection signal via the resistance element 15. Supplied to the pin. The source device can recognize the HDMI device based on the hot plug detection signal output from the 19th pin.

  The switch circuit 20 may be configured by a mechanical switch such as a relay.

  11 and 12 are examples in which the switch circuit 20 is configured by a mechanical relay. The switch circuit 20 includes resistance elements 15 and 23 and a relay 22. The relay 22 has a contact part 22-1 and a coil part 22-2. The coil unit 22-2 is made of an exciting coil, for example. When the current flows through the coil portion 22-2, the contact portion 22-1 is turned on. When no current flows through the coil portion 22-2, the contact portion 22-1 is turned off.

  One terminal of the contact portion 22-1 is connected to the 18th pin through the resistance element 15, and the other terminal of the contact portion 22-1 is connected to the 19th pin. One end of the coil portion 22-2 is grounded, and the other end of the coil portion 22-2 is connected to one end of the resistance element 23. The control signal is supplied to the other end of the resistance element 23.

  FIG. 11 shows a state when the HDMI apparatus is powered off. Since the control signal is at the second level (low level), the contact portion 22-1 is in the released state. In this case, since the 18th pin and the 19th pin are opened (high impedance state), a + 5V voltage signal supplied to the 18th pin is connected to the hot plug detection signal via the resistance element 15. Are not output from the 19th pin. Therefore, the source device does not recognize the HDMI device that is the sink device.

  FIG. 12 shows the HDMI device in a power-on state. Since the control signal is at the first level (high level), the contact portion 22-1 is short-circuited, and the + 5V voltage signal supplied to the 18th pin is passed through the resistance element 15 as a hot plug detection signal. It is supplied to the 19th pin. The source device can recognize the HDMI device based on the hot plug detection signal output from the 19th pin.

  According to the HDMI device of this embodiment, when connected to the source device with the power off, the + 5V voltage is not supplied to the 18th pin of the HDMI connector 11. The level of the hot plug detection signal that is output does not become a high level. For this reason, the source device does not recognize the connection of the HDMI device in the power OFF state to the own device. Therefore, the TMDS signal is not supplied from the source device to the HDMI device in the power-off state, and the HDMI device does not malfunction due to a leakage current generated by supplying the TMDS signal.

  Also in the HDMI device of this embodiment, a latch relay may be used as a switch circuit among mechanical relays as in the first embodiment and the second embodiment. In this case, it is only necessary to supply the control voltage only when switching between short circuit / release between the terminals, so that the power consumption can be reduced.

  Also in the HDMI device of the present embodiment, a control unit other than the HDMI receiver IC may supply a control signal to the switch circuit 20. In this case, the control unit may be, for example, a control circuit that controls the operation of the entire sink device.

  In the HDMI apparatus according to the present embodiment, the memory 12 is deleted, and the HDMI receiver IC 13 receives an access from the source device via the 15th and 16th pins of the HDMI connector 11 and is held by itself. The information 13a may be output from the 15th and 16th pins.

(Fourth embodiment)
FIG. 13 is a block diagram showing a configuration of an HDMI apparatus according to the fourth embodiment of the present invention.

  The HDMI device shown in FIG. 13 has the same configuration as the HDMI device shown in FIG. 8 except that a switch 24 is provided instead of the switch 21 of the switch circuit 20.

  The switch 24 is a mechanical switch such as a semiconductor switch or a relay. The semiconductor switch can be composed of a transistor, an FET, or a combination thereof.

  The switch 24 has first to third terminals. The first terminal is connected to the 19th pin through the resistance element 15. The second terminal is connected to the 18th pin, and the third terminal is grounded.

  In the switch 24, in accordance with a control signal from the HDMI receiver IC 13, a first state in which the first terminal and the second terminal are connected, and a second state in which the first terminal and the third terminal are connected, Is switched between.

  When the control signal is at the first level (high level), the switch 24 is in the first state, and the 18th pin and the 19th pin are short-circuited via the resistance element 15. In this case, a + 5V voltage signal supplied to the 18th pin is output from the 19th pin as a hot plug detection signal via the resistance element 15. Accordingly, the source device detects that the hot plug detection signal is at a high level, and recognizes the HDMI device that is the sink device.

  On the other hand, when the control signal is at the second level (low level or ground potential), the switch 24 is in the second state, and the 19th pin is grounded via the resistance element 15. In this case, since the + 5V voltage signal is not supplied to the 19th pin, the source device cannot recognize the HDMI device as the sink device.

  According to the HDMI device of the present embodiment, the following operational effects are obtained.

  The 19th pin is connected to the input of the detection circuit of the source device via the signal cable. Therefore, when the 19th pin is released (high impedance state), disturbance noise etc. May be input to the source device via the signal line, and the source device may malfunction. According to the HDMI device of the present embodiment, the 19th pin is connected to the 18th pin or GND (ground) via the resistance element 15, so that the 19th pin is never released. . Therefore, it is difficult to be affected by noise.

  Further, if the 19th pin is directly connected to GND (ground), malfunction may occur depending on the circuit configuration on the source device side. According to the HDMI device of the present embodiment, the 19th pin is connected to GND (ground) via the resistance element 15 (resistance value is, for example, 1 kΩ), so that such malfunction is suppressed. Can do.

  In the HDMI apparatus according to the present embodiment, the memory 12 is deleted, and the HDMI receiver IC 13 receives an access from the source device via the 15th and 16th pins of the HDMI connector 11 and is held by itself. The information 13a may be output from the 15th and 16th pins.

  In each of the embodiments described above, the HDMI receiver IC 13 outputs a high-level control signal from the control signal output terminal during the period when the HDMI device is turned on, and other than the above period (the HDMI device is not turned on). In the state), the voltage of the control signal output terminal is set to the low level (ground potential). Instead, the high-level control signal is applied during the period when the HDMI receiver 13 or the communication unit of the HDMI receiver 13 is activated. The voltage is output from the control signal output terminal, and the voltage of the control signal output terminal may be at a low level (ground potential) outside the above period. In the case of the communication unit of the HDMI receiver 13, for example, even when the HDMI receiver IC 13 does not have a malfunction prevention function, it is possible to prevent malfunction. Here, the communication unit of the HDMI receiver 13 receives, for example, a video signal, an audio signal, a clock signal, and / or a control signal transmitted from an external device (source device) via the connector 11. When the HDMI receiver IC 13 holds the EDID information 13a, the communication unit of the HDMI receiver 13 may include the EDID information 13a. The state in which the communication unit of the HDMI receiver IC 103 or the HDMI receiver IC 103 is activated includes, for example, a state in which the communication unit of the HDMI receiver IC 103 or the HDMI receiver IC 103 is turned on, For example, the initialization of the communication unit is completed, and the HDMI receiver IC 103 or the communication unit of the HDMI receiver IC 103 is ready to communicate with a source device that is an external device.

  Each of the embodiments described above is an example of the present invention, and changes that can be understood by those skilled in the art can be applied to the configurations and operations without departing from the spirit of the invention.

  Moreover, although this invention can take a form like the following additional remarks 1-18, it is not limited to these forms.

[Appendix 1]
A connector portion connected to an external device via a signal cable, the connector portion having at least first and second pins, and a predetermined voltage from the external device is applied to the first pin; Electronic equipment to be supplied,
A communication unit to which a signal is input from the external device via a pin other than the first and second pins of the connector unit, and when the communication unit is activated, A control unit that outputs a signal of 1;
An output unit that outputs a first detection signal indicating that there is no connection to the external device to the external device via the second pin when the first signal is not output; Electronic equipment that has.

[Appendix 2]
The electronic device according to appendix 1, wherein the output unit outputs a low level or a ground potential as the first detection signal when the first signal is not output.

[Appendix 3]
The output unit includes a switch for setting the second pin to a low level or a ground potential during a period in which the first signal is input as a control signal and the first signal is not input. Electronic equipment.

[Appendix 4]
The switch includes first to third resistance elements, a MOSFET, and a transistor.
The emitter of the transistor and the source of the MOSFET are each grounded,
One end of the first resistance element is connected to one end of the second resistance element, and is connected to the first pin of the connector portion,
The other end of the first resistance element is connected to the drain of the MOSFET and to the second pin of the connector part,
The other end of the second resistance element is connected to the gate of the MOSFET and to the collector of the transistor,
The first signal is supplied to the base of the transistor via the third resistance element;
During a period when the first signal is not output, the transistor is turned off, the MOSFET is turned on,
The electronic apparatus according to appendix 3, wherein the transistor is turned on and the MOSFET is turned off during a period in which the first signal is output.

[Appendix 5]
The switch has a resistance element and a switch element,
The switch element includes first to third terminals, the first terminal is connected to the first pin of the connector portion, the second terminal is grounded, and the third terminal is Connected to the second pin of the connector portion through the resistance element;
During the period when the first signal is output, the first terminal and the third terminal of the switch element are connected, and during the period when the first signal is not output, The electronic device according to appendix 3, wherein the second terminal and the third terminal are connected.

[Appendix 6]
The electronic device according to appendix 1, wherein the output unit outputs the first detection signal by releasing the second pin when the first signal is not output.

[Appendix 7]
The electronic device according to appendix 6, wherein the output unit is configured to release a space between the first pin and the second pin when the first signal is not output.

[Appendix 8]
The output unit includes a switch and a resistance element to which the first signal is input as a control signal,
The first pin is connected to one end of the switch through the resistance element, the second pin is connected to the other end of the switch element, and the switch does not receive the first signal. The electronic device according to appendix 7, wherein a period is set between the first pin and the second pin.

[Appendix 9]
The output unit includes a relay to which the first signal is input as a control signal, and first and second resistance elements,
The first pin is connected to one terminal of the relay via the first resistance element, the second pin is connected to a terminal at the other end of the relay, and the relay is connected to the first terminal. The electronic device according to appendix 7, wherein a period between the first pin and the second pin is released during a period in which no signal is input.

[Appendix 10]
The switch has a resistance element and a switch element,
One end of the resistance element is connected to the first pin of the connector part, and the other end of the resistance element is connected to the second pin of the connector part via the switch element,
The switch element according to claim 7, wherein the switch element is in an ON state during a period in which the first signal is output, and the switch element is in an OFF state during a period in which the first signal is not output. Electronics.

[Appendix 11]
When the first signal is output, the output unit outputs a second detection signal indicating that there is a connection with the external device to the external device via the second pin. The electronic device according to any one of appendices 1 to 10.

[Appendix 12]
The output unit outputs a signal of the predetermined voltage supplied to the first pin as the second detection signal from the second pin during a period in which the first signal is output. The electronic device according to attachment 11.

[Appendix 13]
A non-volatile memory in which identification data indicating the resolution and format of the video / audio signal is stored;
The electronic device according to any one of appendices 1 to 12, wherein the connector unit further includes a pin for the external device to read the identification data from the nonvolatile memory.

[Appendix 14]
The control unit holds identification data indicating the resolution and format of the video / audio signal,
The electronic device according to any one of appendices 1 to 12, wherein the connector unit further includes a pin for the external device to access the control unit and acquire the identification data.

[Appendix 15]
The electronic device according to any one of appendices 1 to 14, wherein the communication unit is activated when the communication unit is powered on.

[Appendix 16]
The electronic device according to any one of appendices 1 to 14, wherein the state where the communication unit is activated is a state where initialization of the communication unit is completed.

[Appendix 17]
A sink device comprising the electronic device according to any one of appendices 1 to 16,
A source device connected to the sink device via a communication cable,
A communication system in which the source device recognizes that the sink device is connected to the source device when the source device supplies a predetermined voltage to the sink device and receives a detection signal of the predetermined voltage from the sink device.

[Appendix 18]
A connector unit connected to an external device via a signal cable, the connector unit being a hot plug control method performed in an electronic device including at least first and second pins;
A predetermined voltage is applied to the first pin from the external device in a state where a communication unit to which a signal is input from the external device via a pin other than the first and second pins of the connector unit is not activated. When being supplied, the first detection signal indicating that there is no connection with the external device is output to the external device via the second pin,
When the predetermined voltage is supplied from the external device to the first pin in a state where the communication unit is activated, a signal of the predetermined voltage supplied to the first pin is transmitted to the second pin. A hot plug control method for outputting to the external device as a detection signal via the second pin.

  In the above supplementary notes 1 to 18, the control unit is the HDMI receiver IC or the like in the first to fourth embodiments. The HDMI receiver IC 13 is an example of a control unit. The connector unit and the output unit are the HDMI connector and the switch circuit in the first to fourth embodiments, respectively.

  Also, a detection signal output from the second pin and indicating that there is a connection with an external device may be generated using a predetermined voltage supplied to the first pin.

  This application claims priority based on PCT / JP2012 / 74555 filed on September 25, 2012 and Taiwan Patent No. 101136805 filed on October 5, 2012, the entire disclosure of which is incorporated herein by reference. Capture here.

Claims (18)

A connector portion connected to an external device via a signal cable, the connector portion having at least first and second pins, and a predetermined voltage from the external device is applied to the first pin; Electronic equipment to be supplied,
A communication unit to which a signal is input from the external device via a pin other than the first and second pins of the connector unit, and when the communication unit is activated, A control unit that outputs a signal of 1;
An output unit that outputs a first detection signal indicating that there is no connection to the external device to the external device via the second pin when the first signal is not output; Electronic equipment that has.   The electronic device according to claim 1, wherein the output unit outputs a low level or a ground potential as the first detection signal when the first signal is not output.   The output unit includes a switch that sets the second pin to a low level or a ground potential during a period in which the first signal is input as a control signal and the first signal is not input. The electronic device described. The switch includes first to third resistance elements, a MOSFET, and a transistor.
The emitter of the transistor and the source of the MOSFET are each grounded,
One end of the first resistance element is connected to one end of the second resistance element, and is connected to the first pin of the connector portion,
The other end of the first resistance element is connected to the drain of the MOSFET and to the second pin of the connector part,
The other end of the second resistance element is connected to the gate of the MOSFET and to the collector of the transistor,
The first signal is supplied to the base of the transistor via the third resistance element;
During a period when the first signal is not output, the transistor is turned off, the MOSFET is turned on,
4. The electronic device according to claim 3, wherein the transistor is turned on and the MOSFET is turned off during a period in which the first signal is output. The switch has a resistance element and a switch element,
The switch element includes first to third terminals, the first terminal is connected to the first pin of the connector portion, the second terminal is grounded, and the third terminal is Connected to the second pin of the connector portion through the resistance element;
During the period when the first signal is output, the first terminal and the third terminal of the switch element are connected, and during the period when the first signal is not output, The electronic device according to claim 3, wherein the second terminal and the third terminal are connected.   The electronic device according to claim 1, wherein the output unit outputs the first detection signal by releasing the second pin when the first signal is not output.   The electronic device according to claim 6, wherein the output unit releases a space between the first pin and the second pin when the first signal is not output. The output unit includes a switch and a resistance element to which the first signal is input as a control signal,
Wherein the first pin is connected to one end of the switch via the resistor element, the second pin is connected to the other end of said switch, said switch, said first signal is not input The electronic device according to claim 7, wherein the period is a state where a space between the first pin and the second pin is released.
The output unit includes a relay to which the first signal is input as a control signal, and first and second resistance elements,
The first pin is connected to one terminal of the relay via the first resistance element, the second pin is connected to a terminal at the other end of the relay, and the relay is connected to the first terminal. The electronic apparatus according to claim 7, wherein a period between the first pin and the second pin is released during a period in which no signal is input. The switch has a resistance element and a switch element,
One end of the resistance element is connected to the first pin of the connector part, and the other end of the resistance element is connected to the second pin of the connector part via the switch element,
The switch element is in an on state during a period in which the first signal is output, and the switch element is in an off state in a period during which the first signal is not output. Electronic equipment.   When the first signal is output, the output unit outputs a second detection signal indicating that there is a connection with the external device to the external device via the second pin. The electronic device according to any one of claims 1 to 10.   The output unit outputs a signal of the predetermined voltage supplied to the first pin as the second detection signal from the second pin during a period in which the first signal is output. The electronic device according to claim 11. A non-volatile memory in which identification data indicating the resolution and format of the video / audio signal is stored;
The electronic device according to claim 1, wherein the connector unit further includes a pin for the external device to read the identification data from the nonvolatile memory. The control unit holds identification data indicating the resolution and format of the video / audio signal,
The electronic device according to claim 1, wherein the connector unit further includes a pin for the external device to access the control unit and acquire the identification data.   The electronic device according to claim 1, wherein the state in which the communication unit is activated is a state in which the power of the communication unit is turned on.   The electronic device according to claim 1, wherein the state in which the communication unit is activated is a state in which initialization of the communication unit is completed. A sink device comprising the electronic device according to any one of claims 1 to 16,
A source device connected to the sink device via a communication cable,
A communication system in which the source device recognizes that the sink device is connected to the source device when the source device supplies a predetermined voltage to the sink device and receives a detection signal of the predetermined voltage from the sink device. A connector unit connected to an external device via a signal cable, the connector unit being a hot plug control method performed in an electronic device including at least first and second pins;
A predetermined voltage is applied to the first pin from the external device in a state where a communication unit to which a signal is input from the external device via a pin other than the first and second pins of the connector unit is not activated. When being supplied, the first detection signal indicating that there is no connection with the external device is output to the external device via the second pin,
When the predetermined voltage is supplied from the external device to the first pin in a state where the communication unit is activated, a signal of the predetermined voltage supplied to the first pin is transmitted to the second pin. A hot plug control method for outputting to the external device as a detection signal via the second pin.

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