JPH05347589A - Optical signal transmitter/receiver - Google Patents

Abstract

PURPOSE:To provide an optical signal transmitter/receiver which easily transmits both video and stereo audio signals and facilitates free setting of an AV equipment. CONSTITUTION:An optical signal transmitter/receiver consists of an optical transmitting part including a video FM modulation part 1 and an audio FM modulation part 2 which modulate a composite video signal and an analog stereo audio signal with different modulation frequencies, a 1st light emitting part 3 and a 2nd light emitting part 4 which convert the modulated video and audio signals into the optical signals and radiates these signals into space in the same direction, and a 3rd light emitting part 5 which converts only the audio signal into an optical signal and radiates the signal into the space in a different direction from the video signal, and a light receiving part including a 1st light receiving part 7 and a 2nd light receiving part 8 which receive the video and audio signals radiated in the same direction from the optical transmitting part respectively, and a video FM demodulation part 9 and an audio FM demodulation part 10 which demodulate the received video and audio signals respectively. The modulation frequencies of the video and audio signals are set at such degrees that are free from any interference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical signal transmitter / receiver used for optical space transmission for simultaneously transmitting a video signal and an analog audio signal.

[0002]

2. Description of the Related Art In recent years, devices such as CDs and DATs that transmit digital audio signals in the optical space have been released.
For audiovisual equipment such as video discs and videotape recorders (hereinafter referred to as AV equipment), an optical transmitter / receiver for spatially transmitting a video signal and an analog stereo audio signal by using an infrared light LED has been developed. There is.

A conventional optical transmitter / receiver for transmitting video / audio signals will be described below with reference to FIG.

According to the figure, 41 is a video FM modulator,
The video signal supplied from the outside is FM-modulated. An audio FM modulator 42 FM-modulates an analog stereo audio signal supplied from the outside. Numeral 43 is a light emitting part for image,
The modulated video signal is converted into an optical signal and radiated into space.
Reference numeral 44 is a light emitting unit for sound, which converts the FM modulated sound signal into an optical signal and radiates it into space. Reference numeral 45 denotes a video light receiving unit that receives a video signal converted into an optical signal. Reference numeral 46 denotes a voice light receiving unit that receives a voice signal converted into an optical signal. 47
Demodulates the video signal received by the video FM demodulation unit. 48
Is an audio FM demodulation unit that demodulates the received audio signal.

Next, the operation of the optical transmitter / receiver having the above configuration will be briefly described. An NTSC composite video signal is input to the video FM modulator 41. The left FM and right channel analog stereo audio signals are input to the audio FM demodulation unit 42 of the other demodulation unit. The input video signal and analog stereo audio signal are FM-modulated by the video FM modulator 41 and the audio FM modulator 42, respectively. The modulation frequency of the video signal is, for example, center frequency: about 8 MHz to 10 MHz. The modulation frequency of the audio signal is, for example, the center frequency of the left channel: 2.3 MHz, the center frequency of the right channel: 2.8 M
It is about Hz. The video signal and the analog stereo audio signal, which have been respectively modulated, are converted into optical signals by the video light emitting section 43 and the audio light emitting section 44, and then radiated into space. The respective optical signals radiated into the space are received by the video light receiving unit 45 and the audio light receiving unit 46 and converted into electric signals. The converted electric signal is demodulated into the original video signal and audio signal by the video FM demodulation unit 47 and the audio FM demodulation unit 48, respectively.

[0006]

However, in the above-mentioned conventional configuration, it is necessary to transmit the video signal and the audio signal in the same direction (TV monitor main body) without fail when the recorded tape is reproduced and monitored on the TV, for example. is there. At this time, the center frequency of the video signal and the center frequency of the audio signal are close to each other, and they interfere with each other and the signal cannot be demodulated normally. In addition, the audio signal is often transmitted to an amplifier or a speaker that is relatively freely installed, and there is a problem that the AV device cannot be freely set only by transmitting in the same direction as the video signal. ..

[0007]

In order to solve the above-mentioned problems, the optical signal transmitting / receiving apparatus of the present invention is supplied from the outside.
Video F that modulates a composite video signal of TSC system or PAL system into an FM signal having a center frequency around 12 MHz
An M modulation section, a first light emitting section for converting the modulated video signal into an optical signal and radiating it into space, and an analog stereo (left channel and right channel) audio signal supplied from the outside, a modulation frequency of the video signal. And an audio FM modulator that performs FM modulation at different frequencies, a second light emitting unit that converts the modulated audio signal into an optical signal and radiates it in a space in the same direction as the video signal, and a different emission direction of the audio signal. Direction to convert sound signal into optical signal and radiate into space
An optical transmitting unit including a light emitting unit and a switch unit for controlling ON / OFF of radiation of the second light emitting unit and the third light emitting unit;
A first light receiving unit that receives the optical signal of the first light emitting unit and converts it into an electric signal, a video FM demodulation unit that demodulates the electric signal and reproduces an NTSC video signal, and an optical signal of the second light emitting unit. An optical signal transmitting / receiving device is configured by an optical receiving unit including a second light receiving unit for receiving and converting into an electric signal and an audio FM demodulating unit for demodulating the electric signal and reproducing an analog stereo audio signal.

[0008]

As described above, the optical signal transmission / reception apparatus modulates the composite video signal and the analog stereo audio signal, which are supplied from the outside, with the modulation frequencies different from each other, and then outputs the video signal and the audio signal to the optical signal in each light emitting section. After being converted to a space in the same direction, the sound signal is converted into an optical signal by a different light emitting unit and then emitted into a space in a direction different from that of the video signal. Since it is composed of an optical receiving unit that receives the emitted video signal and audio signal and reproduces the signal in each demodulation unit, the video signal and audio signal do not interfere with each other.
Further, it is possible to increase the degree of freedom in setting AV equipment.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the optical signal transmitting / receiving apparatus of the present invention,
This will be described with reference to FIG.

As shown in FIG. 1, reference numeral 1 is a video FM modulator for setting and modulating a composite video signal supplied from the outside in the vicinity of a center frequency of 12 MHz, and 2 is a different analog stereo audio signal supplied from the outside similarly to the above. An audio FM modulator that sets and modulates at a center frequency, 3 is a first light emitting unit that converts a modulated video signal into an optical signal and emits it into space, and 4 is an optical signal that is a modulated analog stereo audio signal Is a second light emitting part which is converted into an optical signal and is emitted into the space. Reference numeral 5 is a third light emitting part which converts the modulated analog stereo audio signal into an optical signal and emits the optical signal in a direction different from the emitting direction. It is a switch unit that controls the output of the optical signal of the second light emitting unit 4 and the third light emitting unit 5, and these form an optical transmitting unit. Reference numeral 7 is a first light receiving portion for receiving the video signal emitted into the space, 8 is a second light receiving portion for receiving the analog stereo audio signal emitted in the space in the same direction as the video signal, and 9 is received. A video FM demodulation unit that demodulates a video signal and outputs the video signal to the outside, and 10 is an audio F that demodulates the received analog stereo audio signal and outputs the analog stereo audio signal to the outside.
It is an M demodulation unit, and these form an optical reception unit.

Next, the usage of the optical AV transmitter / receiver of the above embodiment will be described. The optical transmitter is installed on the side of AV equipment having a source signal such as a video tape recorder, and the optical receiver is the optical transmitter. Install in the vicinity of AV equipment such as a TV in a place separated from the space. Further, AV devices such as an amplifier and a speaker are installed in a place separated from the optical receiver by a space.

Next, the operation of each part will be described. First, the optical transmitter will be described. The video FM modulator 1 includes an NTSC (National Television System Committ) supplied from the outside.
ee) system and PAL (Phase Alternate Line) system composite video signals at the center frequency 1 in the video FM modulator 1.
The frequency shift is set to around 2 MHz and the frequency shift is set to about 2 MHz, and FM modulation is applied. In this FM modulation, the frequency band of the video signal is limited to the range of 6 MHz to 20 MHz (for example, the band is limited by a bandpass filter or the like) to avoid collision with other signals in space. This modulated video signal is sent to the first light emitting unit 3
It is converted into an optical signal by and is emitted to the space toward the optical receiver. The audio FM modulator 2 which is another modulator FM-modulates an analog stereo (left channel and right channel) audio signal supplied from the outside. In FM modulation, the center frequency of the audio signal of the left channel is 2.3M
Set the frequency deviation near Hz to about 150 KHz. For FM modulation of another right channel audio signal, the center frequency is set to around 2.8 MHz and the frequency deviation is set to about 150 KHz. Each of the modulated audio signals is converted into an optical signal by the second light emitting unit 4, and is emitted to the optical receiver in the space in the same direction as the video signal. Further, the analog stereo audio signal supplied from the outside, which has been subjected to the FM modulation, is converted into an optical signal by the third light emitting unit 5, and then an AV such as an amplifier or a speaker installed in a place separated from the optical receiver by a space.
Emit to the device.

Usually, this AV equipment is provided with a light receiving section for receiving the above analog stereo audio signal and performing FM demodulation and a demodulating section, and can reproduce the analog stereo audio signal from the third light emitting section 5. The outputs of the second light emitting unit 4 and the third light emitting unit 5 are controlled by the switch unit 6. That is, as described in the arrangement at the beginning, the optical receiver is installed near the AV device such as a TV at a place separated from the optical transmitter by a space, and the AV device such as an amplifier and a speaker is installed as an optical receiver. It is installed in places separated by space. From this,
When sending the analog stereo audio signal to only the optical AV receiver, the second light emitting section 4 may be turned on, and when sending the analog stereo audio signal only to the amplifier and the speaker, the third light emitting section 5 may be turned on. Just turn it on. Furthermore, in order to send an analog stereo audio signal to both, the second light emitting unit 4 and the third light emitting unit 5 may be turned on.

Next, the optical receiver will be described. The video signal and the analog stereo audio signal transmitted from the optical transmitter through the space are the first light receiving unit 7 and the second light receiving unit 8 of 7.
Each is received by and converted into an electric signal. Usually, in space, various lights (high-frequency lighting fluorescent lights, remote controls,
Signals such as sunlight and optical signals for other spatial transmission are mixed. It is necessary to extract the video signal and analog stereo audio signal sent from the optical transmitter. Therefore, the first light receiving unit 7 and the second light receiving unit 8 are provided with an optical filter that blocks light other than infrared light and an electric filter that blocks frequency components other than those used for signal transmission,
Only the necessary signals are received. The video FM demodulation unit 9 demodulates the FM-modulated video signal received through the optical filter and the electric filter, and outputs the external (T
The composite video signal is sent to an AV device such as a V monitor. Similarly to the above, the audio FM demodulation unit 10 of the other demodulation unit demodulates the FM-modulated analog stereo audio signals received through the optical filter and the electric filter, and sends them to the outside.

FIG. 2 shows another embodiment of the optical signal transmitting / receiving apparatus of the present invention, which particularly deals with surround sound signals.

According to the figure, the surround sound signal supplied from the outside is composed of an analog stereo sound signal viewed by the front speaker and an analog stereo sound signal viewed by the rear speaker. Audio FM modulator 21
Of the surround audio signals, the first audio FM modulator 22 for FM-modulating the audio signals of the front left channel and the front right channel, and the first audio FM modulator 22 for the audio signals of the rear left channel and the rear right channel. Modulator 2
The second voice F, which is FM-modulated at the same modulation frequency as 2
It is composed of the M modulator 23. First audio FM modulator 2
2 and the audio signals of the front left channel and the rear left channel of the second audio FM modulator 23 have center frequencies of 2.
Add FM modulation at 3 MHz. The other front right channel and rear right channel audio signals are FM-modulated with a center frequency of 2.8 MHz. The front analog stereo audio signal modulated by the audio FM modulator 22 is converted into an electric signal by the first light emitting unit 41 and then emitted to the space. The rear analog stereo audio signal modulated by the other audio FM modulator 23 is converted into an electric signal by the second light emitting unit 51 and then emitted to the space. As described above, the surround sound signal can be transmitted.

FIG. 3 also shows an embodiment of the optical signal transmitting / receiving apparatus of the present invention, and particularly relates to an optical receiver.

The same parts as those of the embodiment of FIG. 1 are given the same numbers and their explanations are omitted. In the optical AV receiver, the TV and VTR are separated from the optical AV transmitter by a space.
Are installed in the vicinity of the AV device, and AV devices such as an amplifier and a speaker are installed in a place separated from the optical AV receiving device by a space.

The audio FM modulator 31 is connected to an analog stereo audio output terminal of a TV or audio equipment. FM modulation with the center frequency set to about 2.3 MHz and the frequency deviation set to about 150 KHz is added to the audio signal of the left channel of this analog stereo audio signal. In addition, the center frequency of the right channel audio signal is 2.
F near 8MHz and frequency deviation set to about 150KHz
Add M modulation. Each of these modulated audio signals
The light emitting unit 2 converts it into an optical signal and emits it toward space, and the optical receiving unit is provided with a function of transmitting an audio signal of an AV device.

[0020]

As is apparent from the above description, the optical signal transmitting / receiving apparatus of the present invention allows the center frequency of the video signal and the center frequency of the audio signal to approach each other even if the video signal and the audio signal are transmitted in the same direction. The signals can be demodulated normally without interfering with each other. Further, the audio signal can be transmitted to an amplifier or a speaker installed relatively freely, and not only transmission in the same direction as the video signal but also free setting of AV equipment can be achieved.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an optical signal transmitting / receiving apparatus of the present invention.

FIG. 2 is a block diagram of an optical receiver, which is a main part of another embodiment.

FIG. 3 is a block diagram of an optical receiver, which is a main part of another embodiment.

FIG. 4 is a block diagram of a conventional optical signal transmitter / receiver device.

[Explanation of symbols]

 1 Video FM Modulator 2, 21 Audio FM Modulator 3, 41 First Light Emitting Section 4, 51 Second Light Emitting Section 5 Third Light Emitting Section 7 First Light Receiving Section 8 Second Light Receiving Section 9 Video FM Demodulating Section 10 Audio FM Demodulating Part 22 First audio FM modulator 23 Second audio FM modulator 31 Audio FM modulator 32 Light emitting part

Claims (3)

[Claims] 1. NTSC system or PAL supplied from outside
A video FM modulator that modulates a composite video signal of the method into an FM signal having a center frequency in the vicinity of 12 MHz, and a first FM that converts the modulated video signal into an optical signal and emits it to space.
A light emitting section, an audio FM modulating section for FM-modulating an externally supplied analog stereo (left channel and right channel) audio signal at a frequency different from the modulation frequency of the video signal, and the modulated audio signal as an optical signal. A second light emitting part which is converted and radiates in a space in the same direction as the video signal; a third light emitting part which converts an audio signal into an optical signal in a direction different from the radiating direction of the audio signal and radiates into the space; An optical transmitting unit configured by a switch unit for controlling on / off of radiation of the second light emitting unit and the third light emitting unit, a first light receiving unit for receiving the optical signal of the first light emitting unit and converting it into an electric signal, Video F that demodulates electrical signals and reproduces NTSC video signals
Light composed of an M demodulation unit, a second light receiving unit that receives the optical signal of the second light emitting unit and converts it into an electric signal, and an audio FM demodulation unit that demodulates the electric signal and reproduces an analog stereo audio signal. An optical signal transmitter / receiver configured with a receiver. 2. A first audio FM modulator for FM-modulating audio signals of a front left channel and a front right channel of at least an externally supplied surround audio signal, and a rear left channel and a rear right channel. It is composed of an optical transmitter having a second audio FM modulator that FM-modulates an audio signal at the same modulation frequency as that of the first audio FM modulator, and an optical receiver that receives the optical signal from the optical transmitter. Optical signal transmitter and receiver. 3. An optical transmitter, an audio FM modulator for FM-modulating at least an analog stereo (left channel and right channel) audio signal supplied from the outside, and a space for converting the modulated audio signal into an optical signal. An optical signal transmission / reception device including a light receiving unit having a light emitting unit for radiating light to the.