JP2006222767A - Multi-channel infrared receiver and multi-channel infrared transmitting/receiving system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an infrared receiver capable of optionally controlling the output sensitivity of each sound when a plurality of sounds are switched and output. <P>SOLUTION: The multi-channel infrared receiver for receiving infrared signals is provided with: a selection state setting means SW for setting any one of sound signals of a plurality of channels to a sound selection state; a photodiode 11 for photoelectrically converting the infrared signals to output infrared receiving signals; a demodulation circuit part 20 for selectively demodulating the sound signal set to the sound selection state out of infrared receiving signals output from the photodiode 11; a plurality of resonance circuits 14, 15 to be switched and connected to the output terminal side of the photodiode 11 in accordance with the sound selection state; and a sensitivity control circuit part 16 having a capacity component generated by the photodiode 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multi-channel infrared transceiver for receiving an infrared signal in which audio signals are multiplexed into a plurality of channels and each of the audio signals includes a plurality of audio elements having different carrier frequencies, and a multi-channel including the same The present invention relates to an infrared transmission / reception system.

  A technique for spatially transmitting an audio signal using infrared rays has been proposed. For example, when listening to sound or music using wireless headphones in an automobile or the like, an infrared transmission device is provided on the reproduction device side such as an audio reproduction device and a video reproduction device mounted in the automobile, and an infrared reception device is provided on the headphones side. Is provided. The infrared transmission device including the light emitting diode converts the audio signal reproduced by the reproduction device into an infrared signal and transmits the infrared signal, and the infrared reception device including the photodiode having light receiving sensitivity in the infrared region receives the received infrared light. The signal is demodulated into an audio signal and output from a speaker (for example, see Patent Document 1).

  Further, audio signals of a plurality of channels can be multiplexed and transmitted from the infrared transmission device to the infrared reception device. In this case, the infrared signal received by the infrared receiver includes a plurality of audio signals having different carrier frequencies. A channel selection switch is provided on the infrared receiving device side, and only the audio signal of the selected channel is output from the speaker.

FIG. 6 is a schematic circuit diagram of a conventional infrared receiver.
As shown in the figure, a photodiode PD that receives an infrared signal transmitted from an infrared transmitter, a demodulator circuit 30 that demodulates an infrared reception signal output from the photodiode PD, and an output terminal side of the photodiode PD And a sensitivity adjustment circuit unit that determines the resonance frequency based on the capacitance of the capacitor C and the inductance of the coil L and the capacitance of the capacitance component Cd of the photodiode PD. I have. Then, the infrared reception signal including the audio signal output from the photodiode PD is demodulated by the demodulation circuit unit and output from the speaker. At this time, in order to increase the sensitivity of the audio signal in the infrared receiving device, the resonance frequency is preferably the same as the carrier frequency of the audio signal transmitted as the infrared signal.
JP 2003-101483 A

  Although there is no problem between the conventional infrared transmission device and infrared reception device when the audio signal of one channel is conveyed using the infrared signal, the audio signal of a plurality of channels is multiplexed and conveyed to the same infrared signal. Then, the problem that the receiving sensitivity of the several audio | voice signal in an infrared receiver differs will generate | occur | produce. Specifically, in an infrared receiving device having a circuit as shown in FIG. 6, the carrier frequency of a plurality of audio signals and the resonance frequency unique to the circuit are different, and thus the sensitivity of each audio signal is different.

  Furthermore, there is no problem when each audio signal is monaural audio (that is, when each audio signal includes only one audio element), but each audio signal includes a plurality of audio elements such as stereo audio. In this case, another problem occurs. It is necessary to demodulate an audio reproduction signal including a plurality of audio elements having different carrier frequencies and output from the speaker. However, if the resonance frequency inherent to the circuit and each carrier frequency are different, the sensitivity changes. This is a problem that the output sensitivity of each sound element constituting the stereo sound is generated and the sound becomes difficult to hear.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a multi-channel infrared receiver capable of freely adjusting the output sensitivity of each sound when switching and outputting a plurality of sounds. It is to provide an infrared transmission / reception system for multiple channels.

  In order to achieve the above object, the multi-channel infrared receiver according to the present invention is characterized in that an audio signal is multiplexed into a plurality of channels, and each of the audio signals includes a plurality of audio elements having different carrier frequencies. A multi-channel infrared receiving apparatus for receiving an infrared signal, wherein a selection state setting means for setting any one of the plurality of channels of audio signals to a voice selection state, and an infrared signal obtained by photoelectrically converting the infrared signal A photodiode that outputs a received signal, a demodulator circuit that selectively demodulates and outputs an audio signal in the audio selection state among the infrared received signals, and a plurality connected to the output terminal side of the photodiode And a sensitivity adjustment circuit unit having a capacitance component generated by the photodiode.

According to the above characteristic configuration, the selection state setting means sets any one of the plurality of audio signals to the audio selection state, and the photodiode multiplexes the audio signals into a plurality of channels. An infrared signal including a plurality of audio elements each having a different carrier frequency is photoelectrically converted to output an infrared reception signal, and a sensitivity adjustment circuit unit is connected to the output terminal side of the photodiodes and a plurality of resonance circuits and photo diodes. The demodulating circuit unit selectively demodulates and outputs an audio signal in an audio selection state among infrared reception signals output from the photodiode. That is, when demodulating the selected audio signal, the resonance circuit connected to the output terminal side of the photodiode is switched and connected so that the resonance frequency of the sensitivity adjustment circuit is closest to the carrier frequency of the audio signal. . As a result, when the audio signal is multiplexed into a plurality of channels, any of the audio signals can be selectively demodulated, and the resonance frequency of the sensitivity adjustment circuit and the carrier frequency of the audio signal to be demodulated can be obtained as desired. Since the relationship can be established, the audio signal can be demodulated and output with a desired sensitivity.
Therefore, an infrared receiving device is provided that can freely adjust the output sensitivity of each sound when a plurality of sounds are switched and output.

  Another characteristic configuration of the multi-channel infrared receiver according to the present invention is such that the selection state setting means is such that the resonance frequency of the sensitivity adjustment circuit unit is closest to the carrier frequency of the audio signal in the audio selection state. , One of the plurality of resonance circuits is connected to the output terminal side of the photodiode. In the present invention, the carrier frequency of the voice signal is determined based on the average value of the carrier frequency of each voice element or other rules when the voice signal includes a plurality of voice elements having different carrier frequencies. Refers to the representative value.

  According to the above characteristic configuration, the selection state setting means connects one of the plurality of resonance circuits to the output terminal of the photodiode so that the resonance frequency of the sensitivity adjustment circuit unit is closest to the carrier frequency of the audio signal in the audio selection state. Since the connection is switched to the side, the resonance frequency becomes a value close to the carrier frequency of the audio signal regardless of which audio signal is selected from among the plurality of audio signals. As a result, each audio signal can be demodulated with good desired output sensitivity. For example, it is possible to listen with the same sound quality regardless of which of the plurality of audio signals is demodulated.

  Another characteristic configuration of the multi-channel infrared receiving device according to the present invention is that the resonance frequency of the sensitivity adjustment circuit unit is set to each of the carrier frequencies of the plurality of audio elements included in the audio signal in the audio selection state. It is in the point set so that it may approach most.

  According to the above characteristic configuration, since the resonance frequency of the sensitivity adjustment circuit unit is set so as to be closest to the carrier frequencies of the plurality of audio elements included in the audio signal in the audio selection state, the audio signal in the audio selection state , Each audio element included in the audio signal can be output with equally good sensitivity. For example, it is possible to listen to the same sound quality by demodulating any of a plurality of sound signals, and to listen to a plurality of sound elements of the right sound and the left sound included in the stereo sound with the same sound quality. It becomes possible.

  In order to achieve the above object, the multi-channel infrared transmission / reception system according to the present invention comprises the multi-channel infrared receiver, and the multi-channel infrared receiver receives audio signals in a plurality of channels. An infrared transmission device that is multiplexed and transmits the infrared signal, and a signal generation device that generates the audio signals of the plurality of channels included in the infrared signal.

  According to the above characteristic configuration, the signal generating device generates an audio signal of a plurality of channels, the infrared transmitting device transmits an infrared signal obtained by multiplexing the plurality of audio signals, and the infrared receiving device is set to the plurality of channels as described above. By selectively demodulating any one of the multiplexed audio signals, it is possible to obtain the same effect as that obtained by the multi-channel infrared receiver.

A configuration of a multi-channel infrared transmission / reception system (hereinafter referred to as “infrared transmission / reception system”) according to the present invention will be described below with reference to the drawings.
FIG. 1 shows an infrared transmission / reception system equipped with a multi-channel infrared receiver (hereinafter referred to as “infrared receiver”) 6, an infrared transmitter 5, and a playback device (signal generator) 1 according to the present invention. It is an example when it is provided inside. As shown in FIG. 1, the video output signal is transmitted to the video output device 4 through the video signal output line 3 among the video output signal and the audio output signal by the playback device 1 such as video and audio provided in the automobile. Then, the audio output signal is output to the infrared transmitter 5 through the audio signal output line 2.

  In the present embodiment, a plurality of channels of audio are output from the playback device 1, and the occupant selects and listens to the audio of any channel. Then, the movie is played back by the playback device 1, and the voice includes, for example, Japanese voice and English voice, and each of the Japanese voice and English voice is constituted by stereo voice. That is, the playback apparatus 1 generates an audio output signal in which an audio signal including a plurality of audio elements such as stereo audio is multiplexed into a plurality of channels such as Japanese and English, and transmits the audio output signal to the infrared transmission apparatus 5.

  The infrared transmission device 5 converts the audio output signal, in which the audio signal is multiplexed into a plurality of channels and each of the audio signals includes a plurality of audio elements having different carrier frequencies, into an infrared signal and transmits the infrared signal. As a result, the occupant can receive the infrared signal by using the infrared receiver 6, so that either the Japanese audio channel or the English audio channel output from the playback device 1 is selected and the Japanese audio channel is selected. You can listen to stereo sound or English stereo sound.

FIG. 2 is a diagram illustrating a state in which the infrared receiver 6 is mounted on the headphones.
As shown in FIG. 2, a power switch 8 of the infrared receiving device 6 and a channel selection switch SW for switching a reception channel are provided in the housing 7. Further, a photodiode 11 that photoelectrically converts an infrared transmission signal transmitted from the infrared transmission device 5 and outputs an infrared reception signal, and a volume switch 9 that adjusts the volume are provided. The photodiode 11 is covered and protected by an infrared transmission cover 10.
The power switch 8 is a switch that is repeatedly turned on and off by repeatedly pressing. The volume switch 9 is a switch that is set to a volume having a size corresponding to the amount of rotation by rotating the volume switch 9. The photodiode 11 can be configured using a photoelectric conversion element such as a PIN photodiode.

FIG. 3 schematically shows a circuit diagram of the infrared receiver 6. However, the power switch 8 and the volume switch 9 are omitted.
As shown in FIG. 3, the infrared receiving device 6 includes a photodiode 11 that photoelectrically converts an infrared signal and outputs the infrared received signal, and a selection that sets one of the plurality of audio signals to the audio selection state. A channel selection switch SW as a state setting means; a demodulation circuit unit 20 that selectively demodulates and outputs an audio signal in the audio selection state out of the infrared reception signals output from the photodiode 11; A plurality of resonance circuits 14 and 15 connected to the output terminal side of the diode, and a sensitivity adjustment circuit unit 16 having a capacitance component Cd (having capacitance “C _d ”) generated by the photodiode 11. A reverse bias voltage is applied to the photodiode 11 by a power supply 12. A capacitor 13 is connected to the input terminal side of the photodiode 11.

The sensitivity adjustment circuit unit 16 includes a resonance circuit 14 and a resonance circuit 15 so that the resonance circuit connected to the output terminal side of the photodiode 11 can be switched by the switching operation by the channel selection switch SW shown in FIG. It has become. That is, when the channel selection switch SW shown in FIG. 2 is switched to the A side (A-CH), the resonance circuit 14 is connected to the output terminal side of the photodiode 11 and the channel selection switch SW is set to the B side ( When the operation is switched to B-CH), the resonance circuit 15 is connected to the output terminal side of the photodiode 11. Resonant circuit 14 is configured with a coil L1 having a capacitor C1 and an inductance _{L 1} with a capacitance _{C 1} is connected in parallel, the resonant circuit 15 and the coil L2 having a capacitor C2 and inductance _{L 2} having a capacitance _{C 2} Configured in parallel.

  The demodulating circuit unit 20 includes a demodulating circuit 17 that operates when power is supplied from the power source 19 when the channel selection switch SW is switched to the A side (A-CH), and the channel selection switch SW is on the B side ( B-CH) and a demodulating circuit 18 that operates by being supplied with power from the power source 19 when switched to B-CH).

  In other words, the demodulation circuit 17 outputs the signal from the photodiode 11 when the resonance circuit 14 is connected to the output terminal side of the photodiode 11 by switching the channel selection switch SW to the A side (A-CH). The received infrared signal is demodulated. Then, the demodulating circuit 18 outputs the signal from the photodiode 11 when the resonance circuit 15 is connected to the output terminal side of the photodiode 11 by switching the channel selection switch SW to the B side (B-CH). The received infrared signal is demodulated.

  Next, the operation of the infrared receiving apparatus when the channel selection switch SW is switched to the A side (A-CH) and when switched to the B side (B-CH) will be described.

  When the channel selection switch SW is switched to the A side (A-CH), the resonance circuit 14 is connected to the output terminal side of the photodiode 11 and the infrared reception signal output from the photodiode 11 is demodulated. Demodulated by the circuit 17. At this time, since the capacitor Cd is apparently connected in parallel to the photodiode 11, the resonance frequency f1 of the circuit including the resonance circuit 14 and the capacitor Cd can be expressed by the following equation (1). it can.

  Therefore, in order to maximize the sensitivity of the audio signal in the audio selection state, the resonance frequency f1 should be closest to the carrier frequency of the audio signal in the audio selection state. Specifically, when the audio signal includes a plurality of audio elements having different carrier frequencies, the average value of the carrier frequency of each audio element or the representative value determined based on other rules is used for sensitivity adjustment. The capacitance of the capacitor C1 and the inductance of the coil L1 may be adjusted to appropriate values so as to be closest to the resonance frequency f1 of the circuit unit 16. That is, the channel selection switch SW connects one of the plurality of resonance circuits 14 and 15 to the output terminal of the photodiode 11 so that the resonance frequency of the sensitivity adjustment circuit unit 16 is closest to the carrier frequency of the audio signal in the audio selection state. It is configured to switch and connect to the side.

  Further, when the channel selection switch SW is switched to the B side (B-CH), the resonance circuit 15 is connected to the output terminal side of the photodiode 11, and the infrared reception signal output from the photodiode 11. Is demodulated by the demodulation circuit 18. At this time, since the capacitor Cd is apparently connected in parallel to the photodiode 11, the resonance frequency f2 of the circuit including the resonance circuit 15 and the capacitor Cd can be expressed by the following formula 2. it can.

Therefore, in order to maximize the sensitivity of the audio signal in the audio selection state, the resonance frequency f2 should be closest to the carrier frequency of the audio signal in the audio selection state. Specifically, when the audio signal includes a plurality of audio elements having different carrier frequencies, the average value of the carrier frequency of each audio element or the representative value determined based on other rules is used for sensitivity adjustment. If the capacitance of the capacitor C2 (described as “C ₂ ”) and the inductance of the coil L2 (described as “L ₂ ”) are adjusted to appropriate values so as to be closest to the resonance frequency f2 of the circuit unit 16. Good. That is, the channel selection switch SW connects one of the plurality of resonance circuits 14 and 15 to the output terminal of the photodiode 11 so that the resonance frequency of the sensitivity adjustment circuit unit 16 is closest to the carrier frequency of the audio signal in the audio selection state. It is configured to switch and connect to the side.

In the present embodiment, the audio signal output from the playback apparatus 1 includes a Japanese audio signal and an English audio signal, and each audio element (right audio element and left audio element) of the Japanese audio signal (stereo audio). ) Is transmitted from the infrared transmitter 5 as infrared signals having carrier frequencies of 2.3 MHz and 2.8 MHz, and each of the voice elements (the right voice element and the left voice element) of the English voice signal (stereo voice) is 3 It is transmitted from the infrared transmitter 5 by infrared signals having carrier frequencies of 2 MHz and 3.8 MHz. The demodulating circuit 17 has a function of a bandpass filter that selectively extracts the frequencies of 2.3 MHz and 2.8 MHz, and the demodulating circuit 18 is a band that selectively extracts the frequencies of 3.2 MHz and 3.8 MHz. It has a pass filter function and a signal amplification function.
Therefore, when the channel selection switch SW is switched to the A side (A-CH), the demodulation frequency 17 is used to demodulate the infrared reception signals having carrier frequencies of 2.3 MHz and 2.8 MHz. It is closest to 2.3 MHz and 2.8 MHz (for example, close to about 2.6 MHz which is an average value of both). As shown in FIG. 4, when the channel selection switch SW is switched to the A side A-CH), the output from the demodulation circuit unit 20 (measured at the measurement point M shown in FIG. 3) is a 2.3 MHz signal. It can be seen that the audio elements included in the Japanese stereo sound are output with approximately the same sensitivity.

When the channel selection switch SW is switched to the B side (B-CH), the resonance frequency f2 is set to 3 so that the demodulation circuit 18 demodulates infrared signals having carrier frequencies of 3.2 MHz and 3.8 MHz. .2 MHz and 3.8 MHz (for example, approaching about 3.5 MHz, which is the average value of both).
The broken line in FIG. 5 shows the output from the demodulation circuit unit 20 (measured at the measurement point M shown in FIG. 3) when the channel selection switch SW is switched to the B side (B-CH). The sensitivity of the 3.2 MHz signal is lower than that of the 3.8 MHz signal. For this reason, the problem that each audio | voice element which comprises English stereophonic sound is output with a mutually different sensitivity has generate | occur | produced. In such a case, the sensitivity curve as shown by the solid line in FIG. 5 is obtained by adjusting the capacitance of the capacitor C2 and the inductance of the coil L2 so as to shift the resonance frequency f2 to the low frequency side. As a result, since the output from the demodulation circuit unit 20 when the channel selection switch SW is switched to the B side (B-CH), the 3.2 MHz signal and the 3.8 MHz signal are substantially the same. It can be seen that each audio element included in the English stereophonic sound is output with substantially the same sensitivity.

  As described above, in the infrared receiving device according to the present invention, the selected audio signal is output with appropriate sensitivity among the audio signals multiplexed on a plurality of channels, and the selected audio signal is selected. Since the audio elements constituting the stereo audio are also output with substantially the same sensitivity, the sound can be easily heard even if the channel is switched.

<Another embodiment>
<1>
The details of the channel selection switch SW in the above embodiment are not described. However, the channel selection switch SW is realized by using a mechanical switch that is switched by a human operation input, or the mechanical switch and the semiconductor switching element that are switched by a human operation input. For example, it can be configured using various switches such as when combined with an electrical switch using GaAs (for example, GaAsFET).

<2>
In the above embodiment, an example in which an infrared transmission / reception system including the playback device 1, the infrared transmission device 5, and the infrared reception device 6 is installed in an automobile has been described. You may install in other places.

<3>
In the above-described embodiment, a case has been described in which each audio signal, such as Japanese audio or English audio, is configured with stereo audio including two audio elements, left audio and right audio. For example, four audio signals are provided. The sound may be composed of a larger number of sound elements such as sound composed of elements (including all sounds such as music, sound, and sound effects). In that case, as shown in FIG. 4 and FIG. 5, the average value of the carrier frequency of each sound element or other representative value is set to a value close to the resonance frequency of the sensitivity adjustment circuit unit, and the output sensitivities of the sound elements are mutually equal. What is necessary is just to adjust the said resonant frequency by changing the structure (a capacitor, a coil, resistance, etc.) of a resonant circuit so that it may become substantially equal.

  The infrared receiving apparatus according to the present invention can be used in a system for selecting and listening to a plurality of sounds such as Japanese sounds and English sounds from time to time.

Schematic diagram of infrared transmission / reception system Schematic diagram of infrared receiver Infrared receiver circuit diagram Graph showing output characteristics of infrared receiver Graph showing output characteristics of infrared receiver Circuit diagram of conventional infrared receiver

Explanation of symbols

6 Infrared receiver 11 Photodiode 14 Resonant circuit 15 Resonant circuit 16 Sensitivity adjustment circuit unit 20 Demodulation circuit unit SW Channel selection switch (selection state setting means)

Claims (4)

A multi-channel infrared receiver for receiving an infrared signal in which audio signals are multiplexed into a plurality of channels and each of the audio signals includes a plurality of audio elements having different carrier frequencies,
Selection state setting means for setting any one of the plurality of channels of audio signals to a voice selection state;
A photodiode that photoelectrically converts the infrared signal and outputs an infrared reception signal;
A demodulation circuit unit that selectively demodulates and outputs the audio signal in the audio selection state among the infrared reception signals;
A multi-channel infrared receiver comprising: a plurality of resonance circuits connected to an output terminal side of the photodiode; and a sensitivity adjustment circuit unit having a capacitance component generated by the photodiode.   The selection state setting means sets any one of the plurality of resonance circuits to the output terminal side of the photodiode so that the resonance frequency of the sensitivity adjustment circuit unit is closest to the carrier frequency of the audio signal in the audio selection state. The multi-channel infrared receiver according to claim 1, wherein the multi-channel infrared receiver is connected to.   3. The multi-channel use according to claim 2, wherein a resonance frequency of the sensitivity adjustment circuit unit is set to be closest to each of carrier frequencies of the plurality of audio elements included in the audio signal in the audio selection state. Infrared receiver.   A multi-channel infrared receiver according to any one of claims 1 to 3, wherein an audio signal received by the multi-channel infrared receiver is multiplexed into a plurality of channels, and the infrared signal is transmitted. A multi-channel infrared transmission / reception system comprising: an infrared transmission device; and a signal generation device that generates the plurality of channels of audio signals included in the infrared signal.

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