TW201414294A - Electronic device, communication system, and hot-plug control method - Google Patents

Abstract

This electronic device is provided with: a connector (11) connected to an external device via a communication cable; a controller (13); and an output unit (14). The connector (11) is provided with at least a first pin and a second pin. A prescribed voltage is supplied from the external device to the first pin. The controller (13) is provided with a communication unit into which a signal is inputted from the external device via a pin other than the first and second pins of the connector (11). When the communication unit is in an activated state, the controller (13) outputs a first signal indicating that the communication unit is in an activated state. In cases when the first signal is not outputted, the output unit (14) outputs, to the external device via the second pin, a detection signal indicating that no connection has been established with the external device.

Description

High-resolution multimedia interface device, communication system and hot plug control method

The present invention relates to a high-resolution multimedia interface device (HDMI device) having an interface according to the HDMI (High-Definition Multimedia Interface) specification.

HDMI is the standard for transmitting video/audio communication interfaces with digital signals. Specifications, recently, provide a variety of machines with interfaces based on the HDMI specification.

The communication system of the HDMI standard is composed of a supply device that sends out an HDMI signal and a receiver that receives an HDMI signal, and connects the supply device and the receiver via an HDMI cable (see Patent Document 1).

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

In the communication system, when the supply device and the receiver are connected by an HDMI cable, processing for transmitting an HDMI signal between the supply device and the receiver is performed.

In the first diagram, an example of the HDMI signal transmission and reception sequence is shown.

Referring to Fig. 1, first, after the supply device supplies a predetermined voltage (for example, +5 V) to the receiver (step S100), the receiver receives the voltage supply, and then transmits the hot plug detection signal to the supply device (step S101).

The supply machine recognizes that the receiver is connected to its own machine based on the hot plug detection signal from the receiver.

The supply device that receives the hot plug detection signal accesses the EDID (Extended Display Identification Data) information to the receiver (step S102), and the receiver transmits the EDID information held by itself to the supply device (step S103). Here, the EDID information is a data set representing information on the function or performance (specifically, format or resolution, etc.) corresponding to the receiver.

The supply machine is identified based on the EDID information obtained from the receiver. After the format or resolution of the image/sound that can be played by the receiver, the image/sound signal corresponding to the format or resolution is transmitted to the receiver in a transmission mode called TMDS (Transition Minimized Differential Signaling) (step S104) .

The receiver receives the TMDS signal from the supply machine (step S105). In addition to the TMDS signal, a clock signal or a control signal is also supplied from the supply machine to the receiver. The receiver performs processing such as playback of the TMDS signal based on the clock signal in accordance with the control signal.

In Fig. 2, an example of the configuration of the receiver is shown.

Referring to Fig. 2, the receiver has an HDMI connector 101, a memory 102, and an HDMI receiver IC (Integrated Circuit) 103.

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

The HDMI connector 101 is a standard type connector of 19 legs. The 19th leg is a pin for outputting a hot plug detection signal. The +5V voltage is supplied from the supply machine to the 18th leg.

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

The 15th leg and the 16th leg are used to read the pin of the EDID information stored in the memory 102. These 15th and 16th legs are respectively connected to the memory 102 and connected to the HDMI receiver IC 103.

Receive TMDS from the supply machine using a portion of the remaining pins Signal, clock signal and control signal. The HDMI receiver IC 103 performs playback processing of the TMDS signal according to the clock signal in accordance with the control signal.

Fig. 3 shows another configuration example of the receiver.

The receiver shown in Fig. 3 removes the memory 102 from the receiver shown in Fig. 2, and the HDMI receiver IC 103 holds the EDID information 104.

In the receiver shown in FIG. 3, the HDMI receiver IC 103 accepts access from the supply device via the fifteenth and sixteenth legs, and outputs the EDID information 104 held by itself from the fifteenth and sixteenth legs. . The other operations are the same as those shown in Fig. 2.

The receiver systems shown in Figures 2 and 3 above are independent of whether the device itself is powered ON. When the +5V voltage is supplied to the 18th leg, the +5V hot plug is output from the 19th pin. Detection signal.

[Advanced technical literature]

[Patent Document 1] JP-A-2011-239386

As described above, the receiver systems shown in the second and third figures described above are configured to output a +5V hot plug detection signal to the supply when a voltage of +5V is supplied from the supply device even when the power is turned off. machine. On the other hand, the supply machine does not have a function of detecting whether or not the power of the receiver connected to the own device has been sent. Therefore, in the receiver shown in FIGS. 2 and 3, when the power is turned off and connected to the supply device, the following problems occur. In addition, here, the power OFF state is not standby. The state (so-called standby state) means the state in which the receiver is not connected to commercial AC power.

First, a problem that occurs when the receiver shown in Fig. 2 is connected to the supply device in the power OFF state will be described.

The supply machine reads the EDID information from the memory 102 in the receiver after receiving the +5V hot plug detection signal from the receiver of the power OFF state. In the receiver shown in Fig. 2, since the EDID information is stored in the memory 102 which is a non-volatile memory, the supply device can read the EDID information from the memory 102 even if the receiver is not powered.

When the supply device acquires EDID information from the receiver in the power-off state, the TMDS signal is supplied to the receiver of the power-off state. Since the TMDS signal is supplied to the receiver of the power supply OFF state, a leakage current occurs in the circuit of the receiver, and as a result, the receiver malfunctions.

Further, in general, the HDMI receiver IC 103 has a malfunction prevention function, and when the power is supplied to the receiver, the malfunction prevention function does not cause malfunction due to the leakage current. However, in the case where the receiver is not supplied with power as described above, since the malfunction prevention function does not function, the malfunction caused by the leakage current becomes severe.

Next, a description will be given of a problem that occurs when the receiver shown in Fig. 3 is connected to the supply device in the power OFF state.

The supply machine accesses the EDID information 104 in the receiver after receiving a +5V hot plug detection signal from the receiver of the power OFF state. In the receiver shown in FIG. 3, since the EDID information 104 is held by the HDMI receiver IC 103, the receiver is not powered. In this case, the supply machine cannot access the HDMI receiver IC 103, and the EDID information 104 cannot be obtained.

The supply machine is in a situation where the EDID information cannot be obtained. Since the function or performance (format or resolution) of the receiver cannot be recognized, the TMDS signal is not supplied to the receiver.

In this way, the supply machine cannot obtain the EDID information after receiving the +5V hot plug detection signal, because the TMDS signal is not supplied to the receiver, so even if the power supply to the receiver is sent, it cannot be at the receiver. Display images.

For example, when the supply device and the receiver are connected via the HDMI cable, after the power supply to the device is supplied and the power of the receiver is supplied, as described above, the supply device cannot obtain the EDID information of the receiver. It is not possible to display images on the receiver.

It is an object of the present invention to provide a high resolution multimedia interface device, a communication system, and a hot plug control method that can solve the above-mentioned problems of malfunction or failure to display images.

In order to achieve the object, according to an aspect of the present invention, a high-resolution multimedia interface device having a connector portion connected to an external device via a communication cable, the connector portion including at least a predetermined voltage supplied from the external device The first pin and the second pin that outputs a hot plug detection signal indicating whether or not the external device is connected to the external device, the high-resolution multimedia interface device having a control unit that is sent to the high-resolution multimedia interface device When the power is turned on, the first signal indicating the subject is output; and The circuit outputs a low level or a ground potential to the second pin when the first signal is not output.

According to another aspect of the present invention, there is provided a high-resolution multimedia interface device having a connector portion connected to an external device via a communication cable, the connector portion including at least a first connection to which a predetermined voltage is supplied from the external device a second pin that outputs a hot plug detection signal indicating whether or not the external device is connected to the external device, the high-resolution multimedia interface device having a control unit that outputs when the high-resolution multimedia interface device is powered on The first signal indicating the purpose; and the circuit is such that the first pin and the second pin are in an open state when the first signal is not output.

According to another aspect of the present invention, there is provided a communication system comprising: a receiver constructed by the above-described high resolution multimedia interface device; and a supply device connected to the receiver via a communication cable; the supply The machine determines that the receiver is connected to its own machine when the receiver receives the hot plug detection signal of the predetermined voltage from the receiver.

According to another aspect of the present invention, a hot plug control method is provided, which is a hot plug control method performed by a high resolution multimedia interface device having a connector portion connected to an external device via a communication cable. The connector portion includes at least the external device A first pin that is supplied with a predetermined voltage and a second pin that outputs a hot plug detection signal indicating whether or not the external device is connected to the external device is supplied to the high-resolution multimedia interface device while being supplied with power The predetermined voltage signal of the first pin is output from the second pin as a hot plug detection signal, and the second pin is set to a low level or a ground potential during a period other than the period, or the first one is set The pin is disconnected from the second pin.

Next, an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)

Fig. 4 is a block diagram showing the configuration of an HDMI device according to the first embodiment of the present invention.

The HDMI device shown in FIG. 4 is a receiver such as a HD (High Definition) TV or a receiver such as a projector, and the main portion thereof is composed of 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. Further, as the HDMI connector 11, in addition to the standard type of connector, a connector of, for example, 29 pins can be used.

The switch circuit 14 is configured to detect a +5V voltage signal of the 18th leg as a hot plug when the control signal is at the first level (high level). The signal is output from the 19th pin, and when the control signal is the 2nd level (low level or ground potential), the signal lower than +5V (low level or ground potential) is used as the hot plug detection signal. Output from the 19th foot.

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

The transistor 19 is an NPN transistor with the emitter grounded.

One end of the resistive element 15 is connected to one end of the resistive element 16, and is connected to the 18th leg of the HDMI connector 11. The other end of the resistive element 15 is connected to the drain of the n-type MOSFET 18, and is connected to the 19th leg of the HDMI connector 11. An NPN transistor can also be used instead of an n-type MOSFET. However, since the +5V voltage signal supplied from the 18th pin has a limitation in current capacity, it is convenient to use an n-type MOSFET that consumes less current.

The other end of the resistive 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 resistive element 17.

The resistance value of the resistance element 15 is 1 kΩ, which is a value according to the HDMI specification. The resistance values of the resistance elements 16, 17 are all 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. In a period other than the period (the state in which the HDMI device is not powered), the voltage of the control signal output terminal is set to a low level (ground potential). This composition can be made by It is realized by a switching element such as a MOSFET. Here, the period during which the power is supplied means a period during which the receiver is connected to the commercial AC power source regardless of whether the receiver performs the normal operation or is in the standby state.

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

In the fifth diagram, the HDMI device in the power-off state is shown as a mode in which the voltage of +5 V is supplied to the 18th leg of the HDMI connector 11.

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

When the transistor 19 is in the OFF state, if a voltage of +5 V is supplied to the 18th leg of the HDMI connector 11, 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 +5 V, the n-type MOSFET 18 is turned on.

When the n-type MOSFET 18 is in the ON state, since the 19th leg is grounded via the n-type MOSFET 18, the voltage level of the 19th leg is lowered to become a low level. As a result, the hot plug detection signal output from the 19th leg becomes a low level.

In the case where the hot plug detection signal is low, the supply device does not recognize the HDMI device.

In the sixth diagram, the operation of the HDMI device in the power-on state is performed in a mode in which the voltage of +5 V is supplied to the 18th leg of the HDMI connector 11.

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 resistive element 17. Therefore, the transistor 19 is in an ON state.

When the transistor 19 is in the ON state, the gate of the n-type MOSFET 18 is grounded via the transistor 19. As a result, the voltage level of the gate of the n-type MOSFET 18 becomes a level 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 leg and the 19th leg are connected only via the resistance element 15, and a +5V hot plug detection signal is output from the 19th leg.

When the supply machine receives a +5V hot plug detection signal, it recognizes that the HDMI device is connected to its own machine. Then, between the supply device and the HDMI device, processing is performed in accordance with the steps of steps S102 to S105 shown in Fig. 1.

According to the HDMI device of the present embodiment, even when the power supply is turned off and the supply device is connected, even if the voltage of +5 V is supplied to the 18th leg of the HDMI connector 11, the hot plug detection from the 19th leg is detected. The level of the signal is also low. Therefore, the supply machine does not recognize the connection of the HDMI device of the power OFF state to its own machine. Therefore, the TMDS signal is not supplied from the supply device to the HDMI device in the power-off state, and the HDMI device malfunctions due to the leakage current caused by the supply of the TMDS signal.

(Second embodiment)

Fig. 7 is a block diagram showing the configuration of an HDMI device according to a second embodiment of the present invention.

The HDMI device of the present embodiment removes the memory 12 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 supply device via the 15th and 16th legs of the HDMI connector 11, and maintains the output from the 15th and 16th pins themselves. EDID Information 13a. The other operations are the same as in the first embodiment.

In the same manner as in the first embodiment, the HDMI device of the present embodiment is connected to the supply device in the state where the power is turned off, and even if the voltage of +5 V is supplied to the 18th leg of the HDMI connector 11, from the 19th branch. The level of the hot plug detection signal output by the foot is also a low level. Therefore, the supply machine does not recognize the connection of the HDMI device of the power OFF state to its own machine. Therefore, the supply device does not access the HDMI device in the power-off state in order to obtain the EDID information.

Further, in the HDMI device of the present embodiment, when the power is turned on, the hot plug detection signal of +5 V is output from the 19th leg. After receiving the +5V hot plug detection signal, after identifying the connection of the HDMI device to its own device, the EDID information is obtained from the HDMI device, and the TMDS signal is supplied to the HDMI device. According to this operation, for example, when the HDMI device that supplies the device and the power supply OFF state is connected by the HDMI cable, and the power of the HDMI device is supplied, the TMDS signal is supplied from the supply device to the HDMI device. Therefore, the HDMI device displays an image based on the TMDS signal.

The HDMI device of each embodiment described above is an example of the present invention, and the configuration or operation thereof may be within the range not exceeding the gist of the invention. Changes that can be understood by those skilled in the art.

For example, in the HDMI device shown in FIGS. 4 and 7, the control unit other than the HDMI receiver IC supplies 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 receiver.

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

(Third embodiment)

Fig. 8 is a block diagram showing the configuration of an HDMI device according to a third embodiment of the present invention.

The HDMI device shown in Fig. 8 replaces the switch circuit 14 of the HDMI device shown in Fig. 4, and the switch circuit 20 is used. 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, the 19th leg) for detecting a hot plug and a ground potential. Further, in the present embodiment, the switch circuit 20 is provided with a switch for supplying a first pin (for example, the 18th leg) to which +5 V is supplied, and the hot plug is detected. The configuration between the second pin (for example, the 19th leg) used.

The switching circuit 20 has a resistive element 15 and a switch 21. The switch 21 is a semiconductor switch. The semiconductor open relationship can be formed by a transistor or FET or a combination of these elements.

When the control signal is at the first level (high level), the switch 21 is turned on, and the 18th leg and the 19th leg are short-circuited via the resistance element 15. In this case, the +5 V voltage signal supplied to the 18th leg is output from the 19th leg as a thermal plug detection signal via the resistance element 15. Therefore, the supply machine detects that the hot plug detection signal is at a high level, and the identification is an HDMI device of the receiver.

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 18th leg and the 19th leg are in an open state (high impedance state). In this case, since the voltage signal of +5 V is not supplied to the 19th leg, the supply machine does not recognize the HDMI device which is the receiver.

Fig. 9 shows the state when the power of the HDMI device is turned off. Since the control signal is the second level (low level), the switch 21 is turned OFF. In this case, since the +5V voltage signal supplied to the 18th leg does not pass through the resistance element 15 and is output as the hot plug detection signal from the 19th leg, the supply device does not recognize the HDMI device which is the receiver. .

Fig. 10 shows the state when the power of the HDMI device is turned ON. Since the control signal is at the first level (high level), the switch 21 is in a short-circuit state, and the +5V voltage signal supplied to the 18th leg is supplied to the 19th branch as a hot plug detection signal via the resistance element 15. foot. Supply machine system root The HDMI machine is identified based on the hot plug detection signal output from the 19th leg.

Alternatively, the switch circuit 20 may be constituted by a mechanical switch such as a relay.

11 and 12 are examples in which the switch circuit 20 is constituted by a mechanical relay. The switching circuit 20 has resistive elements 15, 23 and a relay 22. The relay 22 has a contact portion 22-1 and a coil portion 22-2. The coil portion 22-2 is constituted by, for example, an exciting coil. The current flows to the coil portion 22-2, and the contact portion 22-1 is turned on. When the current does not flow to the coil portion 22-2, the contact portion 22-1 is in an OFF state.

The terminal of one of the contact portions 22-1 is connected to the 18th leg via the resistance element 15, and the other terminal of the contact portion 22-1 is connected to the 19th leg. 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 the state when the power of the HDMI device is turned off. Since the control signal is the second level (low level), the contact portion 22-1 is in an open state. In this case, since the 18th leg and the 19th leg are in an open state (high impedance state), the +5V voltage signal supplied to the 18th leg does not pass through the resistance element 15 and is detected as a hot plug. Signal, output from the 19th leg. Therefore, the supply machine does not recognize the HDMI device that is the receiver.

Fig. 12 shows the state when the power of the HDMI device is turned ON. Since the control signal is at the first level (high level), the contact portion 22-1 is in a short-circuit state, and the +5V voltage signal supplied to the 18th leg is supplied as a hot plug detection signal via the resistance element 15 To the 19th foot. Supply machine The HDMI machine can be identified based on the hot plug detection signal output from the 19th leg.

According to the HDMI device of the present embodiment, when the power is turned off and the supply device is connected, since the voltage of +5 V is not supplied to the 18th leg of the HDMI connector 11, the output from the 19th leg is output. The level of the hot plug detection signal does not become a high level. Therefore, the supply machine does not recognize the connection of the HDMI device of the power OFF state to its own machine. Therefore, the TMDS signal is not supplied from the supply device to the HDMI device in the power-off state, and the HDMI device malfunctions due to the leakage current caused by the supply of the TMDS signal.

In the HDMI device of the present embodiment, as in the first embodiment or the second embodiment, a latching relay can be used as the switching circuit even in the mechanical relay. In this case, since the control voltage is supplied only during the short-circuit/open circuit between the switching terminals, it is possible to reduce the power consumption.

Further, 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 receiver.

This patent application claims priority based on PCT/JP2012/74555 filed on Sep. 25, 2012, the entire disclosure of which is incorporated herein.

11‧‧‧HDMI connector

12‧‧‧ memory

13‧‧‧HDMI Receiver IC

14‧‧‧Switch circuit

15~17‧‧‧resistive components

18‧‧‧n type MOSFET

19‧‧‧Optoelectronics

Figure 1 is used to illustrate the communication system implemented in the HDMI specification. A diagram of an example of the HDMI signal transmission and reception sequence.

Fig. 2 is a block diagram showing an example of the configuration of a receiver.

Fig. 3 is a block diagram showing another configuration example of the receiver.

Fig. 4 is a block diagram showing the configuration of an HDMI device according to the first embodiment of the present invention.

Fig. 5 is a schematic view for explaining an operation when the power of the HDMI device shown in Fig. 4 is turned off.

Fig. 6 is a schematic view for explaining the operation of the HDMI device shown in Fig. 4 when the power is turned ON.

Fig. 7 is a block diagram showing the configuration of an HDMI device according to a second embodiment of the present invention.

Fig. 8 is a block diagram showing the configuration of an HDMI device according to a third embodiment of the present invention.

Fig. 9 is a schematic view for explaining the operation of the HDMI device shown in Fig. 8 when the power is turned off.

Fig. 10 is a schematic view for explaining an operation when the power of the HDMI device shown in Fig. 8 is turned ON.

Fig. 11 is a view for explaining a modification of the HDMI device of the third embodiment of the present invention.

Fig. 12 is a view for explaining a modification of the HDMI device of the third embodiment of the present invention.

11‧‧‧HDMI connector

12‧‧‧ memory

13‧‧‧HDMI Receiver IC

14‧‧‧Switch circuit

15‧‧‧Resistive components

16‧‧‧Resistive components

17‧‧‧Resistive components

18‧‧‧n type MOSFET

19‧‧‧Optoelectronics

Claims (12)

A high-resolution multimedia interface device having a connector portion connected to an external device via a communication cable, the connector portion including at least a first pin to which a predetermined voltage is supplied from the external device, and an output indicating presence or absence of the external device a second pin that connects the hot plug detection signal, the high-resolution multimedia interface device includes: a control unit that outputs a first signal indicating the purpose when the high-resolution multimedia interface device is powered; and a circuit When the first signal is not output, the low level or the ground potential is output to the second pin. The high-resolution multimedia interface device according to claim 1, wherein the circuit supplies the predetermined voltage signal supplied to the first pin as a hot plug detection signal while the first signal is being output. The second pin is output. The high-resolution multimedia interface device of claim 1 or 2, wherein the circuit has a switch, the open relationship is input as the control signal, and during the period in which the first signal is not input, The second pin is set to a low level or a ground potential. The high-resolution multimedia interface device of claim 3, wherein the open relationship has first to third resistive elements, a MOSFET, and a transistor; and an emitter of the transistor and a source of the MOSFET are respectively grounded; One end of the resistor element is connected to one end of the second resistor element, and is connected to the first pin of the connector portion; the other end of the first resistor element is connected to the drain of the MOSFET. And connecting to the second pin of the connector portion; the other end of the second resistive element is connected to the gate of the MOSFET, and is connected to the collector of the transistor; the first signal is passed through the third resistor The element is supplied to the base of the transistor; the transistor is set to an OFF state while the first signal is not being output, and the MOSFET is set to ON; and the first signal is output during the period in which the first signal is output The crystal is set to the ON state, and the MOSFET is set to OFF. A high-resolution multimedia interface device having a connector portion connected to an external device via a communication cable, the connector portion including at least a first pin to which a predetermined voltage is supplied from the external device, and an output indicating presence or absence of the external device a second pin that connects the hot plug detection signal, the high-resolution multimedia interface device includes: a control unit that outputs a first signal indicating the purpose when the high-resolution multimedia interface device is powered; and a circuit When the first signal is not output, the first pin and the second pin are disconnected. The high-resolution multimedia interface device of claim 5, wherein the circuit supplies the predetermined voltage signal supplied to the first pin as a hot plug detection signal during the period in which the first signal is output. The second pin is output. A high resolution multimedia interface device according to claim 5 or 6, wherein the circuit has the first signal input as a control signal a switch and a resistor element; the first pin is connected to one end of the switch via the resistor element, and the second pin is connected to the other end of the switch element, and the open relationship is during a period in which the first signal is not input. The first pin and the second pin are disconnected. The high-resolution multimedia interface device according to claim 5 or 6, wherein the circuit has a relay that inputs the first signal as a control signal, and first and second resistance elements; the first pin passes through the first pin The first resistance element is connected to one of the terminals of the relay, and the second pin is connected to a terminal of the other end of the relay, and the relay is configured to connect the first pin to the first signal while the first signal is not input. The second pin is set to be in an open state. The high-resolution multimedia interface device according to any one of claims 1 to 8, further comprising a non-volatile memory, wherein the memory system stores identification data indicating a resolution and a format of the image/sound signal; the connector The department further includes a pin for the external device to read the identification data from the non-volatile memory. The high-resolution multimedia interface device according to any one of claims 1 to 8, wherein the control unit maintains identification data indicating a resolution and a format of the image/sound signal; the connector unit further includes the external device. A pin for accessing the control unit to obtain the identification data. A communication system having: a high-resolution multimedia material according to any one of claims 1 to 10; a receiver formed by the body interface device; and a supply device connected to the receiver via a communication cable; the supply device identifies the predetermined voltage when the receiver receives the hot plug detection signal of the predetermined voltage from the receiver The receiver is connected to its own machine. A hot plug control method is implemented in a high resolution multimedia interface device having a connector portion connected to an external device via a communication cable, the connector portion including at least a predetermined voltage supplied from the external device The first pin and the second pin that outputs a hot plug detection signal indicating whether or not the external device is connected to the external device: when the high-resolution multimedia interface device is powered on, the first pin is supplied to the first pin The predetermined voltage signal is output from the second pin as a hot plug detection signal, and the second pin is set to a low level or a ground potential during a period other than the period, or the first pin and the first pin are 2 The pin is set to be disconnected.