JPS58179009A - Automatic sound volume controller of on-vehicle audio device - Google Patents

Abstract

PURPOSE:To control automatically the sound volume in response to the ambient noises, by providing a piezoelectric element to detect vibrations of a vehicle. CONSTITUTION:A piezoelectric element 16 attached to a vehicle converts the vibrating energy of the vehicle into electric energy. The noises increase as the number of revolutions of the vehicle engine increases. At the same time, the number of revolutions of the engine is substantially coincident with the degree of vibrations of the vehicle. Therefore the auido output is controlled by amplifying the electric signal, i.e. an output of the element 16 through a buffer amplifier 17. Then a frequency component related to the noise is experimentally extracted through a filter 18 and then amplified and rectified by an amplifier 19 and a rectifier 20 repectively. Then the output DC voltage is supplied to a gain control part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic sound IT adjustment device VC for in-vehicle audio equipment.

Car audio equipment! ! In this case, the noise f violet changes every moment depending on the vehicle's own speed and the surrounding environment while driving.When the surrounding noise is loud, it is adjusted to a high ft1i*, and when there is little noise, it is adjusted to a low sound It. There is a need. Recent high-end cardio equipment has come to be equipped with nine automatic lid adjustment devices to deal with such noise.

A commonly used system is - the sound is picked up by a microphone, which originally has
It is difficult to distinguish between the output from the speaker you are trying to listen to and the noise, and a special circuit is required to extract only the ambient noise. If it is necessary to install the above-mentioned microphone in an environment where it is exposed to a lot of external air, such as a two-wheeled vehicle, it will pick up noise that is not perceptible to the ears, so the automatic volume control will not be performed as soon as the hearing senses are heated. .

The purpose of this invention is to obtain an inexpensive automatic mA moderator that eliminates the above-mentioned drawbacks.
The fact that the volume is approximately proportional to 1 [1], and automatic volume adjustment is performed by detecting the size of the car using a piezoelectric element.

Next, it will be explained using figures.

Diagram N1 shows a conventional example of an automatic volume control device for an in-vehicle car radio. The radio wave arriving from the antenna 1 is amplified and detected by the radio signal processing fi 52, and the audio signal is input to the gain adjustment section 3. In the gain adjustment section 3, the audio signal is controlled by nine DC voltages according to ambient noise, and is manually input to the audio output amplifier 4. 5 is a speaker.

On the other hand, ambient noise is picked up by the micro, amplified by the buffer amplifier 7, and then by the rectifier 8! ifi, and its DC output is amplified by 4 widths by a non-inverting amplifier 9 and sent to an adder 13 Vc.
I can input a lot. A portion of the speaker output of the radio audio you are trying to listen to is input directly to the micro, so
A portion of the speaker output is connected to a buffer amplifier 10 so that only the above-mentioned original audio output is canceled out from the noise. The inverted term of the rectifier 111 is added to the adder 13t/c. Therefore, when the noise is small and only the audio output that is intended to be heard is present, the output of addition @13 is zero. On the other hand, when the noise is large, the output of the adder 13 is controlled to be large, and the output is applied to the amplifier 14 and the sub-S section 3 to increase the audio output.

However, as is clear from the above, in order to remove the audio output input to the micro, 10. The circuit shown in 12.13 is required, resulting in an expensive system.

In addition, if the above audio equipment needs to be installed in a place where it comes into direct contact with the outside air, such as on a motorcycle, the control may operate as if the noise were loud due to sound pressure that cannot be felt by the ears. many.

FIG. 2 shows an embodiment of the present invention which overcomes the above-mentioned drawbacks. 16 is a piezoelectric system installed in the car, which converts the fE energy of the car into electric energy. Generally speaking, is made of ceramic.As the car's engine speed increases, noise due to engine sound and wind fVc increases.
jaIXJ. Since the engine rotation speed almost matches the magnitude of the car's vibration, the output of the piezoelectric element mentioned above is the nausea (
The signal f is amplified by a buffer amplifier 17, and frequency components related to noise are extracted experimentally by a filter J, and the amplification l! j
Width increases with 1g! The output DC voltage is rectified by an LFT generator and inputted to the gain control unit 3, thereby controlling the audio output.

As is clear from the above explanation, the present invention has a piezoelectric cord 16
A circuit for canceling the audio output as in the conventional example is unnecessary, and the system is inexpensive. However, there is an advantage that the sound waves are not erroneously adjusted as if there were noise due to sound pressure that is not felt by the ears.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional device, and FIG. 2 is a block diagram showing an in-vehicle car radio eye/tone adjustment device according to an embodiment of the present invention. In the figure, numeral 3 indicates a gain adjuster, 4 an audio output intensifier, and 16 a pressure 4 adjuster. Agent J! # Faith −

Claims (1)

[Claims] 1. A self-excited f-filter for an in-vehicle audio device, comprising a piezoelectric element for detecting vibrations of a desk, and controlling the output level of an audio intermediate device by the output of the piezoelectric element.