JPS58210795A - Voice control circuit - Google Patents

Abstract

PURPOSE:To lower sensitivity to an impulsive noise inputted to a microphone and to speed up response to a sound input by interposing a comparator between an amplifier and a rectifier. CONSTITUTION:The comparator 5 is interposed between the amplifier 2 and rectifier 6. The voice signal of an amplifier 2 is inputted to the plus terminal of the comparator 5 and a voltage depending upon the division ratio of resistances 3 and 4 is supplied to the minus terminal to decide on a threshold level H. Therefore, when an impulsive noise B is superposed upon the voice signal A, the comparator 5 generates an output E by the noise B, or an output D by the voice exceeding the threshold level C'. Those outputs E and D are rectified by the rectifier 6 with a long time constant to obtain an output F free of response to the impulsive noise B from a comparator 9. Namely, a voice control circuit which has a fast response speed and is tolerant to the impulsive noise is obtained.

Description

[Detailed Description of the Invention] The present invention relates to a voice control circuit that automatically turns off the received audio output of a communication device and the audio output of an audio device only when there is a microphone input, and amplifies and outputs the input from the microphone. I'll go.

The function required of the voice control circuit is to perform the above switching as soon as possible when there is a voice input. If the switching is not performed quickly, for example, when voice control is used to switch a device from receiving to transmitting, there will be an inconvenience that the first tone of the transmitter will be distorted. In order to eliminate this inconvenience,
It is necessary to make the response of the rectifier circuit included in the microphone input detector faster, but if the response is made faster, the above-mentioned switching operation will be performed due to bus noise input to the microphone, resulting in malfunction. occurs.

This will be explained below using figures. FIG. 1 is a block diagram of a conventional voice control circuit.

The voice input to the microphone (1) is amplified by the amplifier (2), and the DC voltage rectified by the rectifier (6) is input to the ←) terminal of the comparator (9). The voltage from the DC power supply supplied to terminal 00 is divided by resistors (7) and (8) and supplied to the (→ terminal) of comparator (9).

Therefore, the threshold gμ level of the comparator (9) is determined by (7) and (8).

That is, when the output voltage of the rectifier (6) is output in proportion to the microphone input and exceeds the threshold level,
A DC voltage Vo is outputted to the output α◇ of the comparator (9).

In Figure 2, A is the output waveform of the amplifier (2), and C is the resistor (7).
, (8) are converted into rectifier inputs. If the response of the rectifier (6) is made faster, there will be only the pulse noise shown in Figure 2B, and the output of the rectifier (6) will have a third
A voltage shown by D in the figure is generated, and the threshold level of the comparator (9) is t,<s3, shown by C in the figure.
A direct current voltage Vo indicated by G in FIG. 4 is outputted to the output (b) of the comparator (9). In other words, pulse noise causes the erroneous operation shown in period T in FIG.

As described above, the two voice controller circuits shown in FIG. 1 have the disadvantage that, even though there is no microphone input, the circuit operates as if there is a microphone input due to noise.

This invention was made to remedy the above-mentioned drawbacks.
The purpose of this invention is to provide a highly reliable voice control circuit that does not malfunction due to pulse noise.
``Hereinafter, in an embodiment of the present invention, the same reference numerals as in FIGS. 5 to 8 indicate the same or corresponding parts.

The difference from FIG. 1 is that a comparator (5) is inserted between the amplifier (2) and the rectifier (6). The audio signal of the amplifier (2) is input to the (→ terminal) of the comparator (5), and the voltage determined by the division ratio of the resistor (3) and (4>) is supplied to the ← terminal to determine the threshold - Drebe ivH. are doing.

Therefore, when the pulse noise shown as B in FIG. 6 is superimposed on the audio signal shown as A, the comparator (
As shown in Fig. 7, the output of 5) has an output E due to noise.
Then, an audio output with a level ldtM is generated.

When the outputs E and D shown in FIG. 7 are rectified by a rectifier (6) with a long time constant, an output F without any response due to pulse noise as shown in FIG. 8 is obtained from the comparator (9). In other words, a two-voice controller circuit that has a fast response speed and is resistant to pulse noise has been obtained.

In addition, in FIG. 5, the part where the received signal of the receiver is cut off by the DC output voltage of the comparator (9) and the part where the audio signal of the other audio system is cut off and the audio input from the microphone is output are omitted.

As is clear from the above description, according to the present invention, by inserting a comparator between the amplifier and the rectifier, the sensitivity to pulse noise input to the microphone can be lowered, and the sensitivity to audio input can be reduced. On the other hand, a voice control circuit with quick response can be realized, which is particularly effective for voice control of in-vehicle audio equipment with large ambient noise.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional voice control circuit.
FIG. 2 is an output waveform diagram of the amplifier, FIG. 3 is an output waveform diagram of the rectifier, FIG. 4 is an output waveform diagram of the comparator, and FIG. 5 is a block diagram showing an embodiment of the two voice controller circuits of the present invention. FIG. 6 is an output waveform diagram of the amplifier, and FIGS. 7 and 8 are output waveform diagrams of the comparator. (1)...Microphone, (2)...Amplifier, (6)
, (9)... comparator, (6)... rectifier. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Shin Kuzuno (1 other person)

Claims (1)

[Claims] (1) A microphone, an amplifier that amplifies the output of this microphone, a first comparator that produces an output when the output of this amplifier is above a certain level, a rectifier that rectifies the output of this first comparator, and A voice control circuit comprising: a second comparator that produces an output when the output of the rectifier is above a certain level.