JP2006332846A - Transmitter of av signal, communication apparatus, and transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmitter and a transmitting method of an AV signal in which transmission of the AV signal and data communication transmitted in a reverse direction of it are achieved without requiring extension of a light emitting element or a light receiving element as compared with a device transmitting only the AV signal. <P>SOLUTION: A first communication apparatus 10 transmitting an AV signal is provided with a drive circuit 12 for generating the drive signal of an LED 11 by receiving the AV signa, and an AND circuit 15 for inputting a receiving signal from the LED 11. The first communication apparatus 10 is arranged, such that the drive signal of an LED 11 is switched between supply and nonsupply by a clock signal CLK, and a signal from the LED 11 is passed to the AND circuit 15, when the drive signal is not supplied. A second communication apparatus 20 for receiving the AV signal employs an LED 21 as a light-receiving means and is arranged, such that the AV signal is extracted by removing the frequency component of the clock signal CLK from the receiving signal of the LED 21 and the LED 21 is driven to emit light, based on the transmitted signal during a period in which there is no received signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an AV signal transmission apparatus and an AV signal transmission method for transmitting video signals and audio signals as optical signals.

  Various proposals have been made for techniques for transmitting an AV (audiovisual) signal to a remote device by infrared rays or the like.

For example, in Patent Document 1, in a device that transmits an AV signal by light emission of an LED (light emitting diode) and receives it by a photodiode, an LED that faces the most efficient direction among a plurality of LEDs is found. A technique for transmitting a light emission signal to the LED is disclosed. Patent Document 2 discloses a technique for modulating a video signal and an audio signal by the SWFM method, converting the signal into an optical signal, and transmitting the optical signal via an optical cable. Patent Document 3 discloses a technique in which a plurality of video signals are superimposed by frequency division multiplexing and transmitted through a single optical cable. Patent Document 4 discloses a technique in which a video signal and a data signal are combined with carrier waves in different frequency regions, transmitted by LED light emission, and received by a photodiode.
JP-A-9-214432 JP-A-6-224881 JP-A-6-46034 JP 2002-158980 A

  When viewing video and audio using a transmission device that transmits video signals and audio signals as optical signals, the user views video and audio on the optical signal receiving side, and video signals and audio from tuner devices and video devices. In general, an AV device that outputs a signal is installed away from the optical signal transmission side.

  In such a device arrangement, when the user remotely operates the AV device with a remote controller (remote controller) or the like, the user is on the signal receiving side, so the remote controller is directed to the remote AV device and the buttons are operated. Rather than pointing the remote control at the receiver of a nearby transmission device, the buttons can be operated more easily. Therefore, convenience is increased if a transmission apparatus for transmitting an AV signal can transmit data such as a remote control signal from the receiving side to the sending side.

  However, if a large number of light emitting elements, light receiving elements, and circuits for transmission devices are added only for transmission / reception of remote control signals, there is a problem that the product cost is greatly increased as compared with the improvement of functions.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an AV signal transmission apparatus and transmission method capable of transmitting an AV signal and data communication such as a remote control signal at a low cost with a simple circuit configuration and a small number of parts.

  In order to achieve the above object, the present invention is an AV signal transmission apparatus having a first communication device and a second communication device for transmitting a video signal or an audio signal by an optical signal, wherein the first communication device comprises: A first light emitting diode that emits light to output an optical signal and receives light from the outside to convert it into an electrical signal, and driving the first light emitting diode in response to an analog video signal or audio signal and corresponding to the signal amplitude A drive circuit for generating a signal, a pulse generation circuit for generating a pulse signal of a first frequency exceeding an upper limit frequency of the frequency band of the analog video signal or audio signal, and a reception signal of the first light emitting diode based on light reception An input circuit to be incorporated therein, and the driving of the light emitting diode is switched on and off by the pulse signal, and the light emitting diode is driven in the on state. While the light is emitted according to the drive signal, the reception signal of the light emitting diode is taken into the input circuit when in the off state, and the second communication device receives light from the outside. A second light-emitting diode that converts to an electrical signal and emits light to output an optical signal; a filter circuit that removes the band component of the first frequency from the received signal of the second light-emitting diode; And a logic circuit that drives the second light emitting diode according to the received signal of the second light emitting diode, and the logic circuit is configured to output the second light emitting diode when the magnitude of the received signal of the second light emitting diode is equal to or less than a threshold value. The second light emitting diode is driven according to a transmission signal, and the second light emitting diode is not driven when the magnitude of the reception signal of the second light emitting diode is equal to or greater than a threshold value. It was constructed.

  According to such a configuration, the light-emitting element and the light-receiving element used for transmitting the AV signal are used as the light-emitting element and the light-receiving element when, for example, transmitting a remote control signal or the like in the reverse direction. And cost of parts can be reduced. In addition, since the signal transmission period and the reception period are switched by turning on / off the transmission of the AV signal with a short pulse, the circuit structure is not complicated and the manufacturing cost can be reduced.

  Preferably, the first light emitting diode and the second light emitting diode are parts having the same element structure. By sharing the parts, an effect that the parts cost can be further reduced can be obtained.

  Specifically, the transmission signal can be a digital signal having a bit rate corresponding to the same frequency as the first frequency or a lower frequency. With such a signal, it is possible to transmit the signal with high accuracy even when the transmission timing is switched based on the received signal of the AV signal.

  More specifically, the transmission signal can be a control signal for a remote controller. With such a configuration, for example, when a video signal is transmitted to a television receiver at a location distant from the video reproduction device using the transmission device of the present invention, the remote control receiver is placed on the television receiver side. The signal can be sent to the video reproduction device via the transmission device. That is, an effect is obtained that the user can operate the button with a comfortable posture by pointing the remote controller at a nearby light receiver.

  In order to achieve the above object, the present invention provides an AV signal transmission method for transmitting a video signal or an audio signal by an optical signal, wherein an analog video signal or audio signal is transmitted on the video signal or audio signal transmission side. In response to this, a drive signal that changes in accordance with the signal amplitude is generated, and a pulse signal having a first frequency that exceeds an upper limit frequency of the frequency band of the analog video signal or audio signal is generated. Switch on / off of drive, drive the light emitting diode by the drive signal in the on state, while receiving the reception signal based on the light reception of the light emitting diode in the off state, and receive the video signal or audio signal , A received signal based on the received light is input from the light emitting diode, and the band component of the first frequency is removed from the received signal. While extracting the video signal or the audio signal of the log, and shall by driving the light emitting diode light outputs the transmission signal based on the transmission signal the magnitude of the received signal is at the threshold value or less.

  With such a configuration, the AV signal is transmitted on the receiving side and the transmitting side of the AV signal using one light emitting diode, and at the same time, transmission data such as a remote control signal is transmitted in the opposite direction. It becomes possible. In addition, the configuration of switching between signal transmission and reception by turning on / off the transmission of the AV signal with a short pulse does not complicate the circuit configuration and realizes AV signal transmission and communication in the opposite direction at low cost. I can do it.

  As described above, according to the present invention, it is possible to transmit an AV signal using one light emitting diode on each of the receiving side and the transmitting side of the AV signal, and at the same time, for example, data such as a remote control signal. It is also possible to perform communication in the reverse direction. In addition, compared with a transmission apparatus that performs only AV signal transmission, the circuit configuration is not complicated, and no additional light-emitting elements or light-receiving elements are required. Thus, such a function can be realized at low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a circuit diagram showing an AV signal transmission apparatus according to this embodiment, and FIG. 2 is a signal waveform diagram showing signals of respective parts of the first communication device and the second communication device.

  The AV signal transmission apparatus according to this embodiment includes a first communication device 10 and a second communication device 20 each having one LED 11 and 21 functioning as a light emitting means and a light receiving means. 10 transmits an analog image signal (for example, a composite signal) from the second communication device 20 to the second communication device 20, and transmits digital data (for example, a remote control operation signal) from the second communication device 20 to the first communication device 10.

  The first communication device 10 includes an LED 11 that functions as a light emitting unit and a light receiving unit, a driving circuit 12 that receives an analog image signal and generates a driving current for the LED 11, and a clock signal CLK that receives and supplies a driving voltage for the LED 11. An inverter 13 that switches supply, a switch circuit 14 that switches connection between the drive circuit 12 and the LED 11 in response to the clock signal CLK, and a clock signal CLK and a reception signal from the LED 11 are input and sent from the second communication device 20. And an AND circuit 15 as an input circuit for capturing the transmitted data, the cathode of the LED 11 is connected to the output terminal of the drive circuit 12 and the input terminal of the AND circuit 15 via the switch circuit 14, and the anode of the LED 11 is connected to the inverter 13 Connected to the output terminal. Although not shown in the figure, a circuit that generates a clock signal CLK is provided therein, thereby forming a pulse generation circuit.

  The clock signal CLK is a pulse signal having a frequency (for example, tens of MHz) that is twice or more the upper limit frequency of the frequency band of the image signal, and operates to switch between the transmission period and the reception period in the first communication device 10. That is, the transmission period of the first communication device is when the clock signal CLK is low level, and the reception period of the first communication device is when the clock signal CLK is high level.

  The switch circuit 14 is composed of, for example, a bipolar transistor or FET, and turns on the connection between the drive circuit 12 and the LED 11 when the clock signal CLK is at a low level, and turns off the connection when the clock signal CLK is at a high level.

  With such a configuration, as shown in the signal waveforms of FIGS. 2A to 2D, when the clock signal CLK is at a low level, a drive voltage is supplied from the inverter 13 to the anode of the LED 11 and from the drive circuit 12. A drive current corresponding to the amplitude of the analog image signal is drawn, whereby light emission with an intensity corresponding to the amplitude of the analog image signal is performed from the LED 11. On the other hand, when the clock signal CLK is at a high level, the drive voltage is not supplied from the inverter 13 to the LED 11 and the light emission of the LED 11 is stopped.

  Further, during a period when the clock signal CLK is at a high level, the switch circuit 14 is turned off, the LED 11 is in a non-biased state, and an electromotive force (received signal) generated in the LED 11 due to incident light from the outside is input to the AND circuit 15. The received signal is inputted and sent from the AND circuit 15 to the internal circuit. On the other hand, when the clock signal CLK is at a low level, the clock signal CLK blocks the signal from the LED 11 side in the AND circuit 15 so that it is not sent to the inside. When the reception signal of the LED 11 is small, a preamplifier may be provided between the LED 11 and the AND circuit 15, and the reception signal of the LED 11 may be amplified by the preamplifier and input to the AND circuit 15.

  The second communication device 20 includes an LED 21 that functions as a light emitting unit and a light receiving unit, a low-pass filter 22 that removes the frequency component of the clock signal CLK from the received signal of the LED 21, and a video amplifier 23 that amplifies the output of the low-pass filter 22. The inverter 25 that receives the reception signal of the LED 21 and generates a pulse signal, the NAND circuit 24 that inputs the pulse signal and transmission data and outputs the logic, and outputs the drive voltage of the LED 21 according to the output of the NAND circuit 24 An inverter 25 that switches on and off the connection between the LED 21 and the ground terminal according to the output of the NAND circuit 24, an output terminal of the inverter 26 at the anode of the LED 21, and a switch circuit 27 at the cathode of the LED 21. , Input of low-pass filter 22 and inverter 25 Child has become connected to each other.

  The LED 21 is the same component having the same element structure as the LED 11 of the first communication device 10, and receives light emitted from the first communication device 10 and generates an electromotive force according to the amount of light, like a photodiode. Convert to electrical signal. Although the receiving sensitivity of the LED is lower than that of the photodiode, for example, when a high-brightness LED is separated by several tens of centimeters to transmit and receive an optical signal, an electric signal of several hundred mV is generated in the receiving LED. I can do it. With such an LED 21, as shown in FIG. 2 (E), a signal having substantially the same waveform as the optical signal sent from the first communication device 10 can be obtained.

  The received signal is input to the low-pass filter 22 to remove the frequency component of the clock signal CLK, and the video amplifier 23 adjusts the gain to restore the analog image signal. As described above, since the frequency of the clock signal CLK is twice or more the upper limit frequency of the frequency band of the analog image signal, the waveform of the image signal can be extracted almost without degradation by the action of the low-pass filter 22.

  As shown in FIG. 2 (F), the received signal from the LED 21 is input to the inverter 25, whereby the inverter 25 generates a pulse signal synchronized with the clock signal CLK of the first transmitter 10. The threshold voltage of the inverter 25 is set low so that the LED 11 of the first communication device 10 is turned off at the time of light emission even when the light emission intensity is weak. When the received signal of the LED 21 is too small, a preamplifier for amplifying the received signal may be provided so that the signal amplified by the preamplifier is input to the inverter 25.

  The pulse signal output from the inverter 25 acts to switch between the transmission period and the reception period of the second communication device 20, that is, the period when the pulse signal is at a high level is the transmission period, and the period at the low level is the reception period. Is done.

  As shown in FIGS. 2G and 2H, during the data transmission period, digital transmission data input to one input terminal of the NAND circuit 24 is output to the inverter 26, and the transmission data is transmitted. A driving voltage is output to the LED 21 at the high level. At the same time, the switch circuit 27 is turned on so that a drive current flows through the LED 21 and the LED 21 emits light. Here, the transmission data is, for example, a command code representing the operation content of the remote controller, and the bit rate is smaller than the bit rate corresponding to the frequency of the clock signal CLK. On the other hand, when the transmission data is at a low level, no drive voltage is supplied to the LED 21 and no light is emitted from the LED 21.

  Then, the second optical signal as shown in FIG. 2 (H) is received by the LED 11 of the first communication device 10 and is sent to the internal circuit via the AND circuit 15 during the reception period of the first communication device 10. It has become.

  As described above, according to the AV signal transmission device of this embodiment, for example, the first communication device 10 and the second communication device 20 are respectively connected to the video device and the television receiver that are installed at a distance from each other. Is connected to the television receiver to send an image signal for viewing, and a remote control receiver of the video device is connected to the second communication device 20 to send the remote control signal to the second communication device 20 and the first communication device. It can be sent to the video apparatus via the communication device 10. As a result, the user can operate the remote controller in an easy posture toward the nearby light receiver on the side of the television receiver that is viewing the image.

  In addition, the transmission of the image signal and the transmission of data such as a remote control signal are performed by the light emission and light reception of the LEDs 11 and 21 provided in the first and second communication devices 10 and 20, respectively. Compared with a transmission apparatus that only transmits AV signals, the number of parts and the part cost of the entire transmission apparatus are not increased so much, and the first communication device 10 and the second communication device 20 are controlled by the clock signal CLK. Since the transmission period and the reception period are switched, the circuit configuration is not complicated and the product cost can be reduced.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above embodiment, an image signal such as a composite signal is exemplified as an AV signal to be transmitted. However, for example, an analog audio signal is transmitted, or an analog signal in which a video signal and an audio signal are superimposed by a unique method. A signal can also be transmitted. Also, transmission data sent in the opposite direction to the AV signal is not limited to the remote control signal, and various signals such as a command code for controlling the AV device can be sent from the television receiver.

  In addition, the first communication device 10 and the second communication device 20 are configured to receive light so that the LEDs 11 and 21 become biasless during the reception period, respectively, but the reverse bias is applied to the LEDs 11 and 21 during these periods. The voltage may be applied, or a circuit for converting the electromotive force generated by the LEDs 11 and 21 into a voltage may be provided to make this voltage a received signal. Further, as the drive circuit 12 of the first communication device 10, a circuit that draws current from the LED 11 is illustrated. For example, a drive voltage that is substantially proportional to the amplitude of the image signal is generated, and the amplitude of the image signal is supplied to the LED 11 by this drive voltage. It may be configured such that a drive current according to the current flows. In addition, the detailed structure and the like shown in the embodiment can be appropriately changed without departing from the spirit of the invention.

It is a circuit block diagram which shows the transmission apparatus of AV signal of embodiment of this invention. It is a signal waveform diagram explaining the signal of each part.

Explanation of symbols

10 First communication device 11 LED
12 Drive circuit 13 Inverter 14 Switch circuit 15 AND circuit 20 Second communication device 21 LED
22 Low-pass filter 23 Video amplifier 24 NAND circuit 25, 26 Inverter 27 Switch circuit

Claims (8)

An AV signal transmission device having a first communication device and a second communication device for transmitting a video signal or an audio signal by an optical signal,
The first communication device is:
A first light emitting diode that emits light to output an optical signal and receives light from outside to convert it into an electrical signal;
A driving circuit that receives an analog video signal or audio signal and generates a driving signal of the light emitting means according to the signal amplitude;
A pulse generation circuit for generating a pulse signal having a first frequency exceeding an upper limit frequency of a frequency band of the analog video signal or audio signal;
An input circuit for taking in a reception signal of the first light emitting diode based on light reception,
The driving of the light emitting diode is switched on and off by the pulse signal, and the light emitting diode is driven in the on state to emit light according to the driving signal, while the light emitting diode is driven in the off state. A received signal is configured to be captured by the input circuit,
The second communication device is
A second light-emitting diode having the same element structure as the first light-emitting diode that receives light from the outside, converts it into an electrical signal, and emits light to output the optical signal;
A filter circuit for removing a band component of the first frequency from a reception signal of the second light emitting diode;
A logic circuit for receiving a digital transmission signal having a bit rate corresponding to the same frequency as the first frequency or a frequency lower than the first frequency and driving the second light emitting diode based on the received signal and the received signal of the second light emitting diode; With
The logic circuit drives the second light emitting diode according to the digital transmission signal when the magnitude of the reception signal of the second light emitting diode is less than or equal to a threshold value, while the magnitude of the reception signal of the second light emitting diode. An AV signal transmission device characterized in that the second light emitting diode is not driven when is equal to or greater than a threshold value. An AV signal transmission device having a first communication device and a second communication device for transmitting a video signal or an audio signal by an optical signal,
The first communication device is:
A first light emitting diode that emits light to output an optical signal and receives light from outside to convert it into an electrical signal;
A drive circuit that receives an analog video signal or audio signal and generates a drive signal of the first light emitting diode according to the signal amplitude;
A pulse generation circuit for generating a pulse signal having a first frequency exceeding an upper limit frequency of a frequency band of the analog video signal or audio signal;
An input circuit for taking in a reception signal of the first light emitting diode based on light reception,
The driving of the light emitting diode is switched on and off by the pulse signal, and the light emitting diode is driven in the on state to emit light according to the driving signal, while the light emitting diode is driven in the off state. A received signal is configured to be captured by the input circuit,
The second communication device is
A second light emitting diode that receives light from the outside, converts it into an electrical signal, and emits light to output an optical signal;
A filter circuit for removing a band component of the first frequency from a reception signal of the second light emitting diode;
A logic circuit that receives the transmission signal and drives the second light emitting diode in response to the received signal and the received signal of the second light emitting diode;
The logic circuit drives the second light emitting diode according to the transmission signal when the magnitude of the reception signal of the second light emitting diode is less than or equal to a threshold value, while the magnitude of the reception signal of the second light emitting diode is An AV signal transmission device configured to not drive the second light emitting diode when a threshold value is exceeded.   3. The AV signal transmission device according to claim 2, wherein the first light emitting diode and the second light emitting diode are parts having the same element structure.   4. The AV signal transmission device according to claim 2, wherein the transmission signal is a digital signal having a bit rate corresponding to a frequency equal to or lower than the first frequency. 5.   The AV signal transmission apparatus according to claim 4, wherein the transmission signal is a control signal of a remote controller. An AV signal communication device for transmitting a video signal or an audio signal by an optical signal,
A first light emitting diode that emits light to output an optical signal and receives light from outside to convert it into an electrical signal;
A driving circuit that receives an analog video signal or audio signal and generates a driving signal of the light emitting means according to the signal amplitude;
A pulse generation circuit for generating a pulse signal having a first frequency exceeding an upper limit frequency of a frequency band of the analog video signal or audio signal;
An input circuit for taking in a reception signal of the first light emitting diode based on light reception,
The driving of the light emitting diode is switched on and off by the pulse signal, and the light emitting diode is driven in the on state to emit light according to the driving signal, while the light emitting diode is driven in the off state. An AV signal communicator configured to receive a received signal into the input circuit. A first light emitting diode that emits light to output an optical signal and receives light from the outside and converts it into an electrical signal; and an analog video signal or audio signal, and a driving signal for the light emitting means corresponding to the signal amplitude A driving circuit for generating, a pulse generating circuit for generating a pulse signal of a first frequency exceeding an upper limit frequency of the frequency band of the analog video signal or audio signal, and a reception signal of the first light emitting diode based on light reception inside An input circuit for capturing, and the driving of the light emitting diode is switched on and off by the pulse signal, and the light emitting diode is driven in the on state to emit light according to the driving signal, while the off state An optical signal output from a first communication device configured such that a received signal of the light emitting diode is taken into the input circuit at the time of Only with a communication device of the AV signal for demodulating a video signal or audio signal,
A second light emitting diode that receives light from the outside, converts it into an electrical signal, and emits light to output an optical signal;
A filter circuit for removing a band component of the first frequency from a reception signal of the second light emitting diode;
A logic circuit that receives the transmission signal and drives the second light emitting diode in response to the received signal and the received signal of the second light emitting diode;
The logic circuit drives the second light emitting diode according to the transmission signal when the magnitude of the reception signal of the second light emitting diode is less than or equal to a threshold value, while the magnitude of the reception signal of the second light emitting diode is An AV signal communicator configured not to drive the second light emitting diode when a threshold value is exceeded. An AV signal transmission method for transmitting a video signal or an audio signal by an optical signal,
On the transmission side of the video signal or audio signal,
Receives an analog video signal or audio signal, generates a drive signal that changes according to the signal amplitude,
Generating a pulse signal having a first frequency exceeding an upper limit frequency of the frequency band of the analog video signal or audio signal;
Switch on / off of driving of the light emitting diode by the pulse signal, while driving the light emitting diode by the drive signal in the on state, input a reception signal based on the light reception of the light emitting diode in the off state,
On the video signal or audio signal receiving side,
Input a received signal based on the received light from the light emitting diode,
While removing the band component of the first frequency from the received signal to extract the analog video signal or audio signal,
An AV signal transmission method comprising driving the light-emitting diode based on a transmission signal and optically outputting the transmission signal when the magnitude of the reception signal is a threshold value or less.

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