JP2003324387A - Optical transmission system, optical receiving mechanism, optical transmission method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To transmit a signal including a plurality of types of signals such as a video signal by infrared light. SOLUTION: An optical transmission mechanism having a plurality of light emitting elements 5 to 7 for converting a plurality of electric signals into a plurality of infrared lights having wavelength bands having different peak wavelengths and outputting the same, A plurality of light receiving filter means 8 to 10
And receiving infrared light passing through the filter means,
A light receiving mechanism having a plurality of light receiving elements for obtaining a predetermined electric signal;
Selectively passes a wavelength band of the conversion means, which is paired with each corresponding light receiving means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission system for transmitting and receiving a signal by optical transmission, and more particularly to an optical transmission system for transmitting a transmission signal using infrared rays.

[0002]

2. Description of the Related Art Conventionally, a video projection system used in a hall, a conference room, a home theater of a general household, or the like, has a signal sending device for sending a video signal, a signal receiving device for receiving the video signal, and a video display. It consists of a monitor or a projector. In some cases, the signal receiving device and the monitor or the projector are integrated, but the transmission between the signal transmitting device and the signal receiving device is performed by cable connection. Further, in recent years, a method has also been used in which transmission between these devices is realized wirelessly. In this case, the signal sending device and the signal receiving device are layout-free, and the range of use of the video projection system can be expanded.

[0003]

By the way, radio waves are currently used for wireless transmission between devices, but in this case, the structure of the device for converting and re-converting a video signal into radio waves becomes complicated. Moreover, there is a problem that the manufacturing cost becomes high.

On the other hand, as another method of wireless transmission, an optical communication device using infrared rays instead of radio waves is known, and is used in a remote control device for AV equipment.
However, the conventional optical communication device can be used for transmission of one type of signal, but must support transmission of a signal including a plurality of types of signals such as a video signal including a luminance signal and a color difference signal. Therefore, it could not be used in the above video projection system.

The present invention has been made in view of the above-mentioned problems, and in optical transmission, it is possible to transmit a plurality of types of signals with a cheap and simple structure, and the optical transmission can be applied to a video transmission system. A transmission system is provided.

[0006]

In order to achieve the above-mentioned object, the first invention (corresponding to claim 1) of the present invention provides a plurality of electric signals having a plurality of red wavelengths having different wavelength bands from each other. An optical transmission mechanism having a plurality of converting means for converting the light into external light and outputting the light, a plurality of filter means to which the infrared light is input, and infrared light having passed through the filter means are received to obtain a predetermined electric power. An optical receiving mechanism having a plurality of light receiving means for obtaining a signal, wherein each of the filter means forms a pair with the corresponding light receiving means and selectively transmits the wavelength band of the converting means. System.

The second invention (corresponding to claim 2)
The filter means of the light receiving mechanism is a first filter that passes infrared light in the predetermined wavelength band and infrared light in an unnecessary wavelength band higher or lower than the predetermined wavelength band, The optical transmission system according to the first aspect of the present invention includes a second filter that blocks or suppresses infrared light in the unnecessary wavelength band.

The third invention (corresponding to claim 3)
Is a plurality of filter means to which a plurality of infrared light having different wavelength bands having different peak wavelengths, which are obtained by converting a plurality of electric signals, are input, and the infrared light that has passed through the filter means is received. A plurality of light receiving means for obtaining a predetermined electric signal, and each of the filter means selectively passes a wavelength band of the specific electric signal, which is paired with the corresponding light receiving means. It is an optical receiving mechanism.

A fourth aspect of the present invention (corresponding to claim 4)
Is a first filter for passing infrared light in the predetermined wavelength band and infrared light in an unnecessary wavelength band higher or lower than the predetermined wavelength band; It is a light receiving mechanism according to a third aspect of the present invention, which has a second filter that blocks or suppresses infrared light.

A fifth aspect of the present invention (corresponding to claim 5)
Is the optical transmission system according to the first aspect of the present invention, wherein the plurality of electric signals are a luminance signal and a color difference signal of a video signal.

A sixth aspect of the present invention (corresponding to claim 6)
Is the optical transmission system according to the first or fifth aspect of the present invention, in which the plurality of electric signals are AM-modulated, FM-modulated, or PCM-modulated.

A seventh aspect of the present invention (corresponding to claim 7)
Is the optical receiving mechanism according to the third aspect of the present invention, wherein the plurality of electric signals are a luminance signal and a color difference signal of a video signal.

In the eighth aspect of the present invention (corresponding to claim 8), the plurality of electric signals are AM modulation, FM modulation or PC.
The third or seventh optical receiving mechanism of the present invention which is M-modulated is:

The ninth invention (corresponding to claim 9)
Is a step of converting a plurality of modulated signals into a plurality of infrared light having wavelength bands each including a different peak wavelength and outputting the infrared light, and having a specific wavelength band when the infrared light is input. An optical transmission method comprising: a step of selectively passing an object; and a step of receiving the selectively passed infrared light to obtain a predetermined one of the plurality of modulated signals.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment) FIG. 1 is a block diagram of a video transmission system using an optical transmission system according to an embodiment of the present invention. As shown in the figure, the video transmission system includes a signal transmission device 10 that outputs a video signal as infrared light.
0, a signal receiving device 200 that receives infrared light and obtains a video signal from the infrared light, and a monitor 300 that obtains a video signal from the signal receiving device 200 and displays the video signal.

In the signal transmission device 100, the video signal source 1 is realized by, for example, a VTR, a high-definition image receiver, a DVD player or the like, and has three types of luminance signal (Y) and two color difference signals (Pb) and (Pr). Is a means for outputting a video signal composed of the above signal. The FM modulator (Y) 2, the FM modulator (Pb) 3, and the FM modulator (Pr) 4 receive the luminance signal (Y), the color difference signal (Pb), and the color difference signal (Pr) from the video signal source 3, respectively. When it receives a signal, it is a means for FM-modulating this and converting it into a modulated signal. Further, the light emitting element (Y) 5, the light emitting element (Pb) 6, the light emitting element (Pr) 7
Is a means which is realized by a light emitting diode or the like, and which receives a modulation signal from each FM modulator and converts it into infrared light. As will be described later, the light emitting element (Y) 5, the light emitting element (P
b) 6 and the light emitting element (Pr) 7 have different optical characteristics.

In the signal receiving device 200, the light receiving element (Y) 8, the light receiving element (Pb) 8, the light receiving element (Pr)
Reference numeral 10 is realized by a phototransistor, a photodiode, or the like, which is provided in one-to-one correspondence with the light emitting element (Y) 5, the light emitting element (Pb) 6, and the light emitting element (Pr) 7, respectively, and receives infrared light. , Is a means for converting this into an electrical signal. As will be described later, the light receiving element (Y) 8, the light receiving element (Pb) 8, and the light receiving element (Pr) 10 have the same light receiving characteristics. The FM demodulator (Y) 20, the FM demodulator (Pb) 21, and the FM demodulator (Pr) 22 include a light receiving element (Y) 8, a light receiving element (Pb) 9, and a light receiving element (Pr) 10.
When the luminance signal (Y), the color difference signal (Pb), and the color difference signal (Pr) are input from the respective units, they are demodulated into the luminance signal (Y), the color difference signal (Pb), and the color difference signal (Pr) modulation signal. , Means for outputting to an external monitor 300. Further, the light receiving filter means is arranged in front of each light receiving element and is a means for selectively passing only a specific one, which will be described later, when infrared light is input. The light receiving filter means (Y) 11 is on the front surface of the light receiving element (Y) 8, the light receiving filter means (Pb) 12 is on the front surface of the light receiving element (Pb) 9,
The light receiving filter means (Pr) 13 is a light receiving element (Pr) 1
It is arranged in front of 0 respectively.

Further, the light receiving filter means (Y) 11,
Each of (Pr) 12 and (Pb) 13 is further composed of two stages of filter elements, and a light receiving filter element (Y2) 17, a light receiving filter element (Pb2) 18, and a light receiving element provided immediately before each light receiving element. Filter element (P
r2) 19, the light receiving filter element (Y2) 17, the light receiving filter element (Pb2) 18, the light receiving filter element (Y1) 14 and the light receiving filter element (P1) provided on the front surface of the light receiving filter element (Pr2) 19 respectively.
b1) 15 and a light receiving filter element (Pr1) 16 are provided. Here, the light receiving filter element (Y1) 14,
The light receiving filter element (Pb1) 15 and the light receiving filter element (Pr1) 16 are produced by alternately stacking 30 to 60 thin films of TiO ₂ and SiO ₂ , for example. Also,
Light receiving filter element (Y2) 17, light receiving filter element (Pb2) 18, light receiving filter element (Pr2) 19
May be made by alternately stacking TiO ₂ and SiO ₂ , or may be made of a resin material such as plastic or a glass material containing a predetermined dye. The latter has the advantage of lower cost than the former.

In the above structure, the light emitting element (Y) 5, the light emitting element (Pb) 6, the light emitting element (Pr) 7
Respectively correspond to the conversion means of the present invention, and form the optical transmission mechanism of the present invention as a whole.

Further, the light receiving filter means (Y) 11,
(Pr) 12 and (Pb) 13 correspond to the filter means of the present invention, and include a light receiving filter element (Y1) 14, a light receiving filter element (Pb1) 15, a light receiving filter element (Pr).
1) 16 corresponds to the first filter of the present invention, and includes a light receiving filter element (Y2) 17 and a light receiving filter element (Pb).
2) 18 and the light receiving filter element (Pr2) 19 correspond to the second filter of the present invention. Also, the light receiving element (Y)
8, the light receiving element (Pb) 9, and the light receiving element (Pr) 10 respectively correspond to the light receiving means of the present invention, and the light receiving filter means and the light receiving element form the light receiving mechanism of the present invention. Further, the dotted line portion in the figure corresponds to the optical transmission system of the present invention.

The operation of the video transmission system having the above configuration will be described to explain the operation of the optical transmission system, the operation of the optical receiving mechanism, and the optical transmission method according to the embodiment of the present invention.

First, the operation of the signal transmission device 100 side will be described. The video signal source 1 outputs a luminance signal (Y) and color difference signals (Pb) and (Pr) as video signals.
2A shows the spectrum of the luminance signal (Y), FIG. 2B shows the spectrum of the color difference signal (Pb), and FIG.
The spectrum of the color difference signal (Pr) is shown in (c).

Next, when the FM modulator (Y) 2 receives the input of the luminance signal (Y), it FM-modulates this and outputs a modulated signal. Similarly, when the FM modulator (Pb) 3 and the FM modulator (Pr) 4 receive the color difference signals (Pb) and (Pr), they are FM-modulated and output a modulated signal. Here, the spectrum of the luminance signal (Y) is shown in FIG.
FIG. 3C shows the spectrum of the color difference signal (Pb) in FIG.
The spectrum of the color difference signal (Pr) is shown in FIG. Since the luminance signal (Y) has a spectrum in the wavelength band twice that of the color difference signals (Pb) and (Pr), the spectrum of the output signal from the FM modulator (Y) is the output of another FM modulator. It has a width almost double that of the signal.

Further, when the light emitting element (Y) 5 receives the input of the modulation signal from the FM modulator (Y) 2, the light emitting element (Y) 5 converts this into infrared light and outputs it to the outside. Similarly, a light emitting element (Pb)
6, the light emitting element (Pr) 7, FM modulator (Pb) 3, F
Each of the M modulators (Pr) 4 receives an input of a modulation signal, FM-modulates these signals, and outputs infrared light.

Here, FIG. 4A shows the spectrum of infrared light output from the light emitting element (Y) 5, and FIG. 4B shows the spectrum of infrared light output from the light emitting element (Pb) 6.
The spectrum of infrared light output from the light emitting element (Pr) 7 is shown in (c). As described above, the three light emitting elements have different light emitting characteristics. That is,
The light emitting element (Y) 4 outputs light in a wavelength band having a peak wavelength of 700 nm, and the light emitting element (Pb) 5 and the light emitting element (Pr) 7 have wavelength bands of 850 nm and 900 nm, respectively. Outputs light. Luminance signal, 2
By outputting each of the two color difference signals as infrared light in different wavelength bands, signal crosstalk is prevented. Although the width of the wavelength band of each optical element is shown as being ± 50 to 80 nm from the peak wavelength, it may be narrower. However, at least the peak wavelength is 100 for each optical element.
It is desirable that they are separated from each other by at least nm.

Secondly, the operation of the signal receiving device 200 side will be described.

Light emitting element (Y) 5, light emitting element (Pb) 6,
The infrared light output from the light emitting element (Pr) 7 reaches the signal receiving device 200. At this time, since each infrared light is not converged but propagates radially, the light receiving filter means (Y) 1
1. All the infrared light output from each light emitting element reaches the light receiving filter means (Pb) 12 and the light receiving filter means (Pr) 13.

Here, the light receiving filter means (Y) 11 will be described as an example. As shown in FIG. 5A, the light receiving filter element (Y1) 14 of the light receiving filter means (Y) 11
Functions as a bandpass filter, and the light emitting element (Y)
It has optical characteristics of transmitting infrared light having a peak wavelength of 5 and visible light having a wavelength of 530 nm or less, which corresponds to the unnecessary wavelength band of the present invention. Therefore, of the infrared light input to the light receiving filter element (Y1) 14, the light emitting element (P
The light emitted from b) 6 and the light emitting element (Pr) 7 is cut here, and the infrared light and the visible light emitted from the light emitting element (Y) 5 reach the light receiving filter element (Y2) 17. The characteristics of the light receiving filter element (Y1) 14 required to receive the infrared light from the light emitting element (Y) 5 have a peak wavelength of 670 nm to 750 nm,
The half width may be about 20 to 100 nm.

Similarly, the light receiving filter means (Pb) 12
The light receiving filter element (Pb1) 15 of the
b) It has an optical characteristic of transmitting infrared light having a peak wavelength of 6 and light having a wavelength of 630 nm or less corresponding to the unnecessary wavelength band of the present invention, and has a light receiving filter means (Pr) 13
The light receiving filter element (Pr1) 16 of the
r) It has an optical characteristic of transmitting infrared light having a peak wavelength of 7 and light having a wavelength of 650 nm or less corresponding to the unnecessary wavelength band of the present invention. Therefore, the infrared light input to the light receiving filter element (Pb1) is emitted from the light emitting element (Pb) 6
Only the light emitted from the light source reaches the light receiving filter element (Pb2) 18 together with the light having a wavelength of 630 nm or less, and the infrared light input to the light receiving filter element (Pr1) is emitted from the light emitting element (Pr) 7. Only wavelength 630
Receiving filter element (Pr2) 1 with light of nm or less
Reach 9. The light receiving filter element (Pb1) 1 necessary for receiving the infrared light from the light emitting element (Pb) 6
In the characteristic of No. 5, the wavelength peak may be 800 nm to 900 nm, and the half width may be about 20 to 100 nm. Further, the characteristics of the light receiving filter element (Pr1) 16 required to receive the infrared light from the light emitting element (Pr) 7 have a peak wavelength of 900 nm to 1000 nm and a half-width of about 50 to 100 nm. I wish I had it.

Next, as shown in FIG. 6A, the light receiving filter element (Y2) 1 of the light receiving filter means (Y) 11.
7 functions as a high-pass filter and has an optical characteristic of blocking light having a wavelength of 530 nm or less including the above-mentioned unnecessary wavelength band. Therefore, the light receiving filter element (Y2) 1
Of the light input to 7, the unnecessary light such as visible light is cut off here, and only the infrared light emitted from the light emitting element (Y) 5 reaches the light receiving element (Y) 8.

Similarly, the light receiving filter means (Pb) 12
The light-receiving filter element (Pb2) 18 and the light-receiving filter element (Pr2) 19 are a high-pass filter that blocks light having a wavelength of 650 nm or less, which is the above-mentioned unnecessary wavelength band. Therefore, the light receiving filter element (Pr2) 19
Only the infrared light emitted from the light emitting element (Pr) 7 reaches the light receiving element (Pr) 10 from the light input to the light receiving element (Pb2) 18, and the infrared light emitted from the light receiving element (Pb2) 18 enters the light emitting element (Pb). ) 6 only infrared light reaches the light receiving element (Pb) 8.

Here, FIG. 7 shows the light receiving characteristics of the light receiving element (Y) 8, the light receiving element (Pb) 9, and the light receiving element (Pr) 10. Each light receiving element includes a light emitting element (Y) 5, a light emitting element (P
b) 6 and the light emitting element (Pr) 7 have good light receiving characteristics for any wavelength band, and convert the received infrared light into an electric signal.

Next, when the FM demodulator (Y) 20 receives the electric signal, it demodulates the electric signal to obtain a luminance signal (Y). Similarly, FM demodulator (Pb) 21, FM
When the demodulator (Pr) 22 receives an electric signal, it demodulates the electric signal and obtains color difference signals (Pb) and (Pr), respectively.

Finally, the luminance signal (Y), color difference signals (Pb), (Pr) output from the signal receiving device 200 are input to the monitor 300, and the monitor 300 displays these video signals as an image.

As described above, according to the present embodiment, the light emitting elements and the light receiving filter means having different characteristics corresponding to a plurality of kinds of signals, and the light receiving elements having the same characteristics and the same number as the light emitting elements are provided. By including the light receiving element, by the light receiving filter means, to selectively receive only infrared rays from a specific light emitting element corresponding to one to one,
It becomes possible to transmit a plurality of types of signals such as video signals. Such an optical transmission system can be used for a wireless video transmission system.

In the above embodiment, the light receiving filter element (Y
2) 17, the light receiving filter element (Pb2) 18 and the light receiving filter element (Pr2) 19 are arranged on the light receiving element side of the light receiving filter element (Y1) 14, the light receiving filter element (Pb1) 15, and the light receiving filter element (Pr1) 16. However, this arrangement may be reversed.

Further, the light receiving filter element (Y1) 14,
Although the light receiving filter element (Pb1) 15 and the light receiving filter element (Pr1) 16 are described as bandpass filters, they may be realized as high pass filters or low pass filters. In short, it is sufficient that the light emitting element has a function of passing infrared light in a predetermined wavelength band and infrared light in an unnecessary wavelength band.

Further, the light receiving filter element (Y2) 17,
Although the light receiving filter element (Pb2) 18 and the light receiving filter element (Pr2) 19 have been described as high pass filters, they may be realized as low pass filters or band pass filters. In short, it is sufficient if it has a function of blocking or suppressing infrared light in the unnecessary wavelength band.

As a light receiving filter element, FIG.
As shown in (a) to (c), the light-emitting element (Y) 5, the light-emitting element (Pb) 6, and the light-emitting element (Pr) 7 have excellent selectivity for passing only infrared light in the respective wavelength bands. If one is used, the light receiving filter means 11 to 13 can have only one light receiving filter element for each light receiving element. However, since such a filter element becomes expensive, it is possible to reduce the cost of the entire apparatus by using two types of inexpensive filters as in the above embodiment.

In the above embodiment, the optical transmission system has been described as having three sets of the light emitting element, the light receiving filter means, and the light receiving element.
You may have two sets or four sets or more. At this time, if the two types of color difference signals (Pb) and (Pr) are time-divided and output by one light emitting element, the video transmission system of the present embodiment is realized by two sets of optical transmission systems. it can.

In the above embodiment, the signal modulated by the FM modulator is optically transmitted, but the signal modulated by AM modulation or PCM modulation may be optically transmitted. . It may be a signal modulated by another modulation format. Further, not only video signals but also audio signals, video and audio signals may be handled.

[0043]

As described above, according to the present invention, it is possible to provide an optical transmission system or the like capable of transmitting a plurality of types of signals with a simple and inexpensive structure in optical transmission.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a video transmission system equipped with an optical transmission system according to an embodiment of the present invention.

FIG. 2A is a diagram showing a spectrum of a luminance signal (Y). (B) It is a figure which shows the spectrum of a color difference signal (Pb). It is a figure which shows the spectrum of (c) color difference signal (Pr).

FIG. 3 (a) is a diagram showing a spectrum of a modulation signal of the FM modulator (Y) 2. (B) It is a figure which shows the spectrum of the modulation signal of FM modulator (Pb) 3. (C) It is a figure which shows the spectrum of the modulation signal of FM modulator (Pr) 4.

FIG. 4A is a diagram showing a spectrum of infrared light of the light emitting device (Y) 5. (B) It is a figure which shows the spectrum of the infrared light of the light emitting element (Pb) 6. It is a figure which shows the spectrum of the infrared light of (c) light emitting element (Pr) 7.

5 (a) is a diagram showing optical characteristics of a light receiving filter element (Y1) 14. FIG. (B) It is a figure which shows the optical characteristic of the light receiving filter element (Pb1) 15. (C) It is a figure which shows the optical characteristic of the light receiving filter element (Pr1) 16.

6 (a) is a diagram showing optical characteristics of a light receiving filter element (Y1) 14. FIG. (B) It is a figure which shows the optical characteristic of the light receiving filter element (Pb1) 15 and the light receiving filter element (Pr1) 16.

FIG. 7 is a diagram showing light receiving characteristics of a light receiving element (Y), a light receiving element (Pb), and a light receiving element (Pr).

FIG. 8 (a) Another configuration example of the light receiving filter means (Y)
It is a figure which shows the optical characteristic of. (B) It is a figure which shows the optical characteristic of the other structural example (Pb) of a light receiving filter means. (C) It is a figure which shows the optical characteristic of the other structural example (Pr) of a light receiving filter means.

[Explanation of symbols]

1 Video signal source 2 FM modulator (Y) 3 FM modulator (Pb) 4 FM modulator (Pr) 5 Light emitting element (Y) 6 Light emitting element (Pb) 7 Light emitting element (Pr) 8 Light receiving element (Y) 9 Light receiving element (Pb) 10 Light receiving element (Pr) 11 Light receiving filter means (Y) 12 Light receiving filter means (Pb) 13 Light receiving filter element (Pr) 14 Light receiving filter element (Y1) 15 Light receiving filter element (Pb1) 16 Light receiving filter element (Pr1) 17 Light receiving filter element (Y2) 18 Light receiving filter element (Pb2) 19 Light receiving filter element (Pr2) 20 FM demodulator (Y) 21 FM demodulator (Pb) 22 FM demodulator (Pr) 100 signal transmitter 200 signal receiver 300 monitors

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04J 14/02 H04N 7/22 (72) Inventor Takeshi Sato 1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. Company (72) Inventor Isao Matsuda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Mitsuru Akata 1006 Kadoma, Kadoma City, Osaka Prefecture F Term (Reference) 5C064 EA02 5K102 AA11 AA15 AB01 AH23 AH26 AH27 AL21 PC05 PC12 PC14 RB03

Claims (9)

[Claims] 1. An optical transmission mechanism having a plurality of converting means for converting a plurality of electric signals into a plurality of infrared light having wavelength bands having different peak wavelengths and outputting the infrared light, and the infrared light is inputted. A plurality of filter means, and an optical receiving mechanism having a plurality of light receiving means for receiving infrared light that has passed through the filter means to obtain a predetermined electric signal, each of the filter means corresponding to the other. An optical transmission system for selectively passing the wavelength band of the conversion means, which is paired with the light receiving means. 2. The first filtering means of the light receiving mechanism passes infrared light in the predetermined wavelength band and infrared light in an unnecessary wavelength band higher or lower than the predetermined wavelength band. The optical transmission system according to claim 1, comprising a filter and a second filter that blocks or suppresses infrared light in the unnecessary wavelength band. 3. A plurality of filter means to which a plurality of infrared lights having different wavelength bands having different peak wavelengths, which are obtained by converting a plurality of electric signals, are input, and an infrared light passed through the filter means. And a plurality of light receiving means for receiving a predetermined electric signal, and each of the filter means selectively selects a wavelength band of the specific electric signal, which is paired with the corresponding light receiving means. Light receiving mechanism that allows light to pass through. 4. The first filtering means for passing infrared light in the predetermined wavelength band and infrared light in an unnecessary wavelength band higher or lower than the predetermined wavelength band, and the unnecessary filter. The optical receiving mechanism according to claim 3, further comprising a second filter that blocks or suppresses infrared light in a wavelength band. 5. The optical transmission system according to claim 1, wherein the plurality of electric signals are a luminance signal and a color difference signal of a video signal. 6. The plurality of electrical signals are AM modulated, FM
The optical transmission system according to claim 1, wherein the optical transmission system is modulated or PCM modulated. 7. The optical receiving mechanism according to claim 3, wherein the plurality of electric signals are a luminance signal and a color difference signal of a video signal. 8. The plurality of electrical signals are AM modulated, FM
The optical receiving mechanism according to claim 3, wherein the optical receiving mechanism is modulated or PCM modulated. 9. A step of converting a plurality of modulated signals into a plurality of infrared light having wavelength bands each including a peak wavelength different from each other, and outputting the plurality of infrared light; An optical transmission method comprising: a step of selectively passing one having a band; and a step of receiving the selectively passed infrared light to obtain a predetermined one of the plurality of modulated signals.