JPS63187933A - On vehicle audio device - Google Patents

Abstract

PURPOSE:To reproduce a sound having a high quality without being caught by various electromagnetic induction noises generated in a vehicle, by providing an optical transmitting unit and an optical receiving unit using a signal light of infrared rays, in the vehicle. CONSTITUTION:An audio electric signal inputted to an optical transmitting unit A through a changeover switch 2 from an equipment 1 is supplied to a light source 14 through a level compressor 11 and an oscillation modulating part 12, and a signal light 15 of infrared rays is radiated into a vehicle from a light source 12. This radiated signal light 15 is received by a receiving part 16 of an optical receiving unit B and converted to an electric signal. This electric signal is supplied to a loudspeaker 6 through an amplifying part 17, a demodulating part 18, a level expanding part 19 and a power amplifier 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an in-vehicle audio device that transmits and receives signal light through optical space transmission using infrared rays.

Conventional technology: In recent years, with the spread of audio equipment such as cassette tape recorders and compact discs, in-vehicle audio equipment has become a system that outputs high-quality high-fidelity sound from speakers. Electrical noise generated from various electrical noise sources, including power lines connected to electrical circuits, mixes between devices connected by conventional signal wiring, power amplifiers, and speakers and is reproduced, affecting the quality of the reproduced sound. decreases.

A conventional in-vehicle audio device is shown in FIG.

In Fig. 5, 1 is equipment such as a radio receiver, cassette tape recorder, compact disc, etc., 2 is a switch that changes the output from these equipment, 3.5 is a signal wiring, 4 is a power amplifier, 6 is a speaker, and 7 8 is a DC power supply, and 9 and 1o are power lines.

In FIG. 5, audio electrical signals output from various devices 1 are selected by a changeover switch 2, guided to a power amplifier 4 via a signal wiring 3'Jr, amplified, and outputted as an audio signal, and then transmitted to a speaker through a signal wiring 5. Drive 6. Power line laid near signal wiring 3.6 9.
Reference numeral 10 supplies power current from a DC power source 8 to the equipment 1, power amplifier 4, electrical equipment, electric circuit 7, and the like.

Problems to be Solved by the Invention However, in the above configuration, the signal wiring and the power line are wired close to each other, so when an electrical component or an electric circuit operates, electrical noise is generated in the power line, and the signal wiring and the power line are wired close to each other. Electrical noise is induced in the signal wiring due to electromagnetic coupling and capacitive coupling between the speaker and the speaker, resulting in a problem in that the noise is significantly mixed into the sound reproduced by the speaker, and the 3N ratio is considerably deteriorated.

In view of the above problems, the main purpose of the present invention is to transmit signal light through optical space transmission using infrared @ and reproduce high-quality audio signals in order to prevent various electromagnetic induction noises generated inside a car. Another object is to provide an improved in-vehicle audio device based on the above object, and another object is to improve the quality of reproduced sound when there is an obstacle between the optical transmitter and receiver. An object of the present invention is to provide an in-vehicle audio device that can achieve the above object by a device that maintains the following.

Means for Solving the Problems In order to solve the above problems, the in-vehicle audio device of the present invention includes a light transmitting unit that emits infrared signal light into space, and a speaker that receives the signal light and outputs an audio signal. It is equipped with an optical receiving unit that reproduces the .

Effect of the Invention With the above-described configuration, the present invention sends signals between the transmitting side and the receiving side by optical space transmission, thereby eliminating electrical noise induced in the signal wiring between conventional equipment, amplifiers, and speakers, and achieving high quality. Audio is played.

Furthermore, when an obstacle exists between the optical transmitter and the receiver and the signal light reaching the optical receiver is weak, the signal to the power amplifier is interrupted.

Embodiment Hereinafter, an in-vehicle audio device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of an in-vehicle audio device according to a first embodiment of the present invention.

In Figure 1, 1 is the equipment, 2 is the changeover switch, and 4
6 is a power amplifier, 6 is a speaker, and the above configuration is the same as that shown in FIG. 11 is a level compressor, 12 is an oscillation modulator, 13 is a light source, 14 is a light source, 15 is a signal light, 16
1 is a light receiving section, 17 is an amplifying section, 18 is a demodulating section, 19 is a level expander, 1 is an optical transmitting unit, and B is an optical receiving unit.

The operation of the in-vehicle audio device configured as described above will be described below.

Optical transmitter unit 7) from device 1 through changeover switch 2
The audio electrical signal input to A is level compressor 1.
1, the level is compressed by the oscillation modulator 12, which transmits a high frequency signal, modulates the high frequency signal by the output from the level compressor 11, and outputs the signal from the light source 14 such as a light emitting diode or semiconductor laser in the light source section 13. An infrared signal light 15 whose intensity changes according to the above-mentioned modulated output signal is emitted into the vehicle. This emitted signal light 1
The signal 5 is received by the light receiving unit 16 of the optical receiving unit (H) located at a position distant from the optical transmitter (22) A, and is converted into an electrical signal. This electric signal is amplified by one level in an amplifying section 17, demodulated in a demodulating section 18, and an audio frequency signal is extracted.

The signal level of the audio frequency signal is expanded by a level expander 19, and the level-compressed signal level is expanded by an optical transmitter unit (A) to greatly improve the S/N ratio. The output from one level expander is amplified by a power amplifier 4 to drive a speaker 6.

As described above, according to this embodiment, the infrared signal light 15 is emitted into space from the optical transmitting unit and is received by the optical receiving unit B, so that electrical noise is induced in the signal wiring as in the conventional case. This eliminates the problem and allows high-quality sound with a high S/N ratio to be played.

Next, a second embodiment of the present invention will be described.

FIG. 2 shows a block diagram of an oscillation modulation section 1'2 of an optical transmission unit in a vehicle audio device according to a second embodiment.

A high frequency oscillator 20 oscillates an analog high frequency signal such as a sine wave. The analog high frequency signal is modulated by an input audio signal generator in a frequency modulator 21. The electrical signal change in the output signal O is converted into a change in light intensity by the light source 14 of the light source section 13, and is emitted into space.

In the above second embodiment, the oscillation modulation section 12 is the high frequency oscillator 2.
Since the optical transmitter/receiver unit (A) is composed of an o and a frequency modulator 21, even if the optical transmitter/receiver units (A and B) are far apart from each other and the light intensity becomes weak,
Since the high frequency signal received by the optical receiver 22) B and subjected to photoelectric conversion is amplified to the maximum, the demodulator 18 can extract an accurate audio frequency signal.

FIG. 3 shows a block diagram of the oscillation modulation section 12 of the in-vehicle audio device showing the third embodiment. In this case, the oscillation modulator 12 has a pulse oscillator 22 which oscillates digital pulses, and the pulse signal is pulse-modulated by a pulse modulator 23. For pulse modulation, means such as normal position modulation, pulse width modulation, and phase modulation are used.

According to the third embodiment, since the signal used is a digital signal, it is more resistant to noise than in the second embodiment, and even higher quality transmission can be performed.

FIG. 4 shows a block diagram of an optical receiving unit B in an on-vehicle audio device showing a fourth embodiment of the present invention.

In FIG. 4, reference numeral 24 denotes a muting switch circuit whose structure is similar to that of FIG. 1.

The signal light incident on the light receiving section 1e of the optical receiving unit (optical receiving unit) B is converted into an electrical signal.

8 is interrupted for some reason, almost no signal light 16 reaches the light receiving section 1e. Therefore, the signal passing through the amplifying section 17 and the demodulating section 18 becomes very small. At this time, the muting switch circuit 24 detects the minute level of this signal and performs a switching operation so that the minute signal is not transmitted to the power amplifier 4 through the level expander 19.

As described above, by providing the muting switch circuit 24, when the signal light 16 received by the light receiving section 16 is weak, the muting switch circuit 24 blocks the noisy audio signal from the power amplifier 4, and from the speaker 6. can be configured to play only high quality sound.

In addition, in the first embodiment, the optical transmitter/receiver unit) A and B light source sections 13, light receiving section 16, and light source 14 were explained as one each, but they can be used in a car depending on the light intensity, light receiving sensitivity, directivity angle, light receiving angle, etc. There may be at least one or more of each.

Effects of the Invention As described above, the present invention provides high-quality sound without being affected by various electromagnetic induction noises generated inside the car by providing an optical transmission unit and an optical reception unit that use infrared signal light inside the car. It is something that can be played. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an in-vehicle audio device according to a first embodiment of the present invention, FIG. 2 is a block diagram of an oscillation modulation section of an in-vehicle audio device in a second embodiment, and FIG. 3 is a block diagram of an oscillation modulation section of an in-vehicle audio device according to a second embodiment. FIG. 4 is a block diagram of the optical receiving unit of the in-vehicle audio device in the fourth embodiment, and FIG. 6 is a block diagram of the conventional in-vehicle audio device. . 1... Equipment, 2... Changeover switch,
11... Level compressor, 12... Oscillation modulation section, 13... Light source section, 14... Light source, 15... Signal light, 16... Light receiving section, 1
7...Additional 111M section, 18...Demodulation section, 1
9... Level expander, 20... High frequency oscillator, 21... Frequency modulator, 22...
...Pulse oscillator, 23...Pulse modulator, 2
4... Muting switch circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person11
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Claims (4)

[Claims] (1) A level compressor that compresses the level of an audio electrical signal output from any in-vehicle device, and oscillation modulation that oscillates a desired high-frequency signal and modulates the high-frequency signal with the output from the level compressor. and at least one light source unit that emits into the vehicle an infrared signal light whose intensity changes according to the output signal from the oscillation modulation unit, at least one light receiving section that receives the signal light emitted from the transmitting unit into the vehicle at a location remote from the optical transmitting unit and converts it into an electrical signal; an amplifying section that amplifies the electrical signal; and an amplifying section that amplifies the electrical signal. A demodulator that demodulates the high frequency signal and extracts an audio frequency signal, a level expander that expands the level of the audio frequency signal, a power amplifier that amplifies the output from the level expander, and a power amplifier that is driven by the power amplifier. What is claimed is: 1. A vehicle-mounted audio device comprising at least one optical receiving unit comprising a speaker and a speaker. (2) The in-vehicle audio device according to claim 1, wherein the oscillation modulation section comprises a high frequency oscillator and a frequency modulator. (3) The in-vehicle audio device according to claim 1, wherein the oscillation modulation section includes a pulse oscillator and a pulse modulator. (4) The in-vehicle audio device according to claim 1, wherein the optical receiving unit includes a muting switch circuit that cuts off the audio signal to the power amplifier when the signal light received by the light receiving section is weak.