JPH05344009A - Transmission modulator - Google Patents

Abstract

PURPOSE:To prevent interception of a voice signal by sending a modulated optical signal corresponding to a sound from a sound source and converting the optical signal into a radio wave corresponding to the sound of the sound source and relaying the converted signal so as to reduce leakage electric field strength. CONSTITUTION:A voice output signal of a movie enters an amplification modulator 12 from a movie set 11, in which the signal is amplified and modulated and the result is sent to an infrared ray transmitter 13. The infrared ray transmitter 13 emits a modulated infrared ray signal 22 and gives the signal 22 to a relay pole 25. The signal is converted into a voice output signal corresponding to the voice output signal of the sound source by the converter and sent to an FM car radio set 50 as an FM radio wave 90. Then a movie voice is reproduced from the FM car radio set 50. Thus, leaked electric field due to leakage of a radio wave between the sound source and the relay means is reduced and interception is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission modulation device having a low electric field intensity, which is optimum for transmitting sound mainly in a drive-in theater or the like.

[0002]

2. Description of the Related Art For a long time, audio transmission in a drive-in theater has been achieved by directly retracting a speaker into an automobile. However, with the spread of car radio,
A method of transmitting medium-wave AM radio waves through a car radio in a vehicle has been generally used. Furthermore, with the spread of FM broadcasting, using FM broadcast radio waves,
Furthermore, it became possible to transmit in stereo.
In this case, an FM car radio popular in automobiles is used as a receiver, and an FM radio wave of a movie sound is sent to this FM car radio. If you are in a car, this FM
Watch the movie on the screen while listening to the audio played on the car radio.

In such a drive-in theater, the system for transmitting audio output has a structure as shown in FIG.

That is, the audio source 1 is connected to the wireless transmitter 3 via the cable 2. A high frequency audio output signal from the wireless transmitter 3 is sent to the cable 4 a via the cable 4 and the distributor 5. The audio output signal is sent from the cables 4 and 4a to the FM car radio of each car 9 by the FM radio wave 8 as shown by the dotted line.

FIG. 6 specifically shows the arrangement of a conventional drive-in theater. A leakage electric field is generated from the cable 4 and the cable 4a connected to each distributor 5.

[0006]

[Problems to be Solved by the Invention] These cables 4,
If the audio output signal in the cables 4 and 4a is set to a small value in order to suppress the electric field strength leaked from the 4a within the legal electric field strength, the FM car radio cannot be provided with a sufficient audio output and is reproduced. Sound quality deteriorates.

On the other hand, if the audio output signal in the cables 4 and 4a is increased in order to give a sufficient audio output to the FM car radio with good sound quality, the leakage electric field strength of the cable 4 can be suppressed within a strict legal electric field strength. Technically difficult. In addition, the leaked electric field causes the voice to be eavesdropped. Therefore, it is difficult to manage the drive-in theater.

It is an object of the present invention to provide a transmission modulation device having a low electric field strength, which can reduce the leakage electric field strength and prevent the eavesdropping of a movie or the like by listening to a sound.

To achieve this object, the present invention provides
The gist of the transmission modulation device according to claim 1 is.

[0010]

The transmission modulator of the present invention sends an output corresponding to the sound of the sound source (voice source 14 in the embodiment) to the relay means (pole 25 in the embodiment) and responds to this output. The radio wave (FM radio wave 90 in the embodiment) emitted from the relay means is transmitted to a plurality of receivers (FM car radio 50 in the embodiment), and the sound of the sound source is reproduced when the sound is reproduced by each receiver. Optical signal 22 modulated by the output corresponding to
Optical signal transmitting means (infrared transmitter 13 in the embodiment) for transmitting the optical signal 22 and the optical signal 22 from the optical signal transmitting means to receive a radio wave (F in the embodiment) corresponding to the sound of the sound source.
The relay means (the pole 25 in the embodiment) for converting and transmitting the M radio wave 90) is provided.

The light is ultraviolet light having a wavelength in the range of approximately 1 to 400 nm, visible light in the range of 400 to 750 nm, and 750.
Infrared rays in the range of nm to 1 mm can be arbitrarily selected.

[0012]

EXAMPLE Referring to FIG.

The projection booth 10 is equipped with a projector 11, an amplification modulator 12, and an infrared transmitter 13. The projector 11 and the amplification modulator 12 constitute the audio source 14 of FIG. The amplification modulator 12 is connected to the infrared transmitter 13 via a cable 15.

The projector 11 projects a movie on the screen 20 as shown in FIGS. The audio output signal of the movie enters the amplification modulator 12 from the projector 11, is amplified and modulated by the amplification modulator 12, and is sent to the infrared transmitter 13 via the cable 15.

The infrared transmitter 13 has, for example, an infrared light emitting diode. The infrared light emitting diode emits an infrared signal 22 modulated based on the amplified and modulated audio output signal, and relays each infrared signal 22.
Give to 5. At this time, the output of the infrared signal 22 is, for example, about 2300 mW. The wavelength used for the infrared signal 22 is, for example, a wavelength centered on near infrared radiation of 950 nm.

The pole 25 is arbitrarily arranged between the screen 20 and the projection booth 10 in FIG.
Each pole 25 has an infrared receiver 30, as shown in FIG.
The converter 31 and the wireless transmitter 32 are provided. The infrared signal 22 is the infrared sensor 80 of the infrared receiver 30.
When it is received (see FIG. 3), it is converted by the conversion device 31 into an audio output signal corresponding to the audio output of the audio source 14. The audio output signal is transmitted to the automobile 40 via the wireless transmitter 32.
Is transmitted to the FM car radio 50 as an FM radio wave 90. The FM car radio 50 reproduces the sound of a movie.

The pole 25 has the structure shown in FIG. The base 60 contains a power source 70, the infrared receiver 30, the converter 31, and a wireless transmitter 32. The wireless transmitter 32 has an antenna 75. An infrared sensor 80 is provided on the top of the pole 25. The infrared sensor 80 is connected to the infrared receiver 30.

At the time of projection, the automobile 40 is stopped near each pole 25 as shown in FIGS. Then, the FM car radio 50 is turned on and stands by.

In the projection booth 10, the projector 11 is operated to send an audio output to each pole 25 as an infrared signal 22 via the infrared transmitter 13. Each pole 2 shown in FIGS. 3 and 4
The infrared sensor 80 of No. 5 receives the infrared signal 22, photoelectrically converts it, and sends it to the infrared receiver 30.

The infrared receiver 30 frequency-converts the electric signal corresponding to the infrared signal 22 by the converter 31 to produce a voice output signal corresponding to the voice output signal of the voice source 14.
This audio output signal is sent to the wireless transmitter 32. According to the second aspect of the present invention, the voice output signal and the pilot signal for regulating the carrier wave frequency / phase of the radio wave transmitted from the wireless transmitter 32 are created and sent to the wireless transmitter 32. The wireless transmitter 32 sends an FM radio wave 90 corresponding to the audio output signal of the audio source 14 to the FM car radio 50. The sound of the sound source 14 is reproduced on the FM car radio 50. The infrared sensor 80 is, for example, a photodiode. ..

In this way, since infrared rays corresponding to the sound output are sent along a long distance from the projection booth 10 to each pole 25, a leak electric field unlike the conventional case does not occur. For this reason, it becomes impossible to illegally listen and listen to a movie by using the leakage electric field. Screen 2
It is not easy to hide the 0 screen from the outside when the screen is installed in an open place. However, by preventing the sound from leaking, it is possible to prevent snooping or sniffing. In any case, a slightly lower leakage electric field is generated from the cable 15 between the infrared transmitter 13 and the sound source 14 in FIG. 2 for a very short time.

Infrared rays are most suitable because they allow the device to be compact and can stably send signals with high directivity to the poles, but other light sources such as ultraviolet rays or visible light rays can also be used. Arranging the poles appropriately can secure any service area.

The present invention is not limited to the above embodiment.

Instead of using the FM car radio of a car as a receiver, a dedicated receiver may be separately sent to the viewers of each car to receive radio waves from Paul. In this case F
It is not limited to M radio waves. The present invention can be applied not only to the drive theater but also to baseball. Therefore, management of facilities such as a drive-in theater becomes easy.

[0025]

As described above, according to the present invention,
The leakage electric field due to the electric wave leakage between the sound source and the relay means can be minimized, and eavesdropping can be prevented.

[Brief description of drawings]

FIG. 1 is a plan view showing a drive-in theater including an embodiment of an oscillation modulator of the present invention.

FIG. 2 is a diagram showing a system for transmitting audio output, which includes an embodiment of the transmission modulator of the present invention.

FIG. 3 is a diagram showing the structure of a pole that is a relay unit in the embodiment of the transmission modulator of the present invention.

FIG. 4 is a perspective view showing a part of a drive-in theater including an embodiment of the transmission modulator of the present invention.

FIG. 5 is a diagram showing a system of audio output transmission in a conventional drive-in theater.

FIG. 6 is a diagram showing a system of audio output transmission in a conventional drive-in theater.

[Explanation of symbols]

 10 Projection Booth 11 Projector 12 Amplification Modulator 13 Infrared Transmitter 14 Sound Source 15 Cable 22 Infrared Signal 25 Pole 30 Infrared Receiver 31 Converter 32 Radio Transmitter 40 Car 50 FM Car Radio 80 Infrared Sensor 90 FM Radio Wave ◆

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04H 1/00 Q 7240-5K U 7240-5K

Claims (2)

[Claims] 1. An output corresponding to the sound of a sound source (14) is transmitted to a relay means (25), and a radio wave (90) emitted from the relay means (25) corresponding to the output is transmitted to a plurality of receivers. (50), and each receiver (50) sends a radio wave (90)
And an optical signal transmitting means (13) for transmitting an optical signal (22) modulated by the output corresponding to the sound of the sound source (14) when reproducing the sound corresponding to
A transmission modulator comprising: a relay unit (25) which receives the optical signal (22) from the light source (3), converts it into a radio wave (90) corresponding to the sound of the sound source (14), and transmits the radio wave (90). 2. The transmitting and modulating apparatus according to claim 1, wherein the optical signal transmitting means (13) transmits together with the voice signal a pilot signal for making the carrier wave frequency / phase of the radio wave (90) constant. , Optical signal transmission means (1
3) and the optical signal (2
A transmission modulation device comprising: a relay unit that receives 2), converts it into a radio wave (90) corresponding to the sound of the sound source (14), and transmits the radio wave (90).