KR20020043370A - Output Circuit of 2-Input Audio Signal - Google Patents

Abstract

PURPOSE: An output circuit of 2 input audio signal is provided to suitably control audio signals which are inputted to both sides by means of an AGC circuit. CONSTITUTION: Filters(100a,100b) pass necessary bandwidth components such as a high or low frequency component among audio signals which are inputted to both sides. Each of the filters(100a,100b) includes a low pass filter for passing a low frequency component, a high pass filter for passing a high frequency component, and a band pass filter for passing a desired band component. AGC circuits(102a,102b) automatically control gains of the signals from the filters(100a,100b) regardless of input changes. Amplifiers(104a,104b) amplify the signals from the AGC circuits(102a,102b) by predetermined rate. A switch(106) switches the audio signal which are inputted to both sides and connects the audio signals to each element. The switch(106) includes a relay.

Description

Output circuit of 2-input audio signal {Output Circuit of 2-Input Audio Signal}

The present invention relates to an output circuit of a two-input audio signal. More particularly, the present invention relates to an output circuit of two-input audio signals. The present invention relates to an output circuit of an input audio signal.

In general, an audio system is an apparatus for recording or reproducing an audio signal on a medium, and a cassette tape, a record, and a disc are used as the medium.

This audio system is basically composed of a turntable, tuner, amplifier, cassette deck, and speaker unit, including an equalizer and a compact disc player. The back is added separately and is comprised.

The audio system includes a music center in which a speaker unit is separated but a tuner, an amplifier, and a cassette deck are composed of one main body, and a component system in which all devices are separated to have professional characteristics. Divided into.

As an example of such an audio system, the music center has an audio system in which a main body and a compact disc player constitute a set of playback devices, and a speaker unit is combined therein, and the speaker unit is an electrical signal. It is one of the transducers that converts the sound into an audio signal and outputs it.

In addition, the audio system is equipped with a radio broadcast receiving system for receiving a radio broadcast signal and outputting a broadcast signal through a speaker.

In general, a system equipped with an audio signal output device such as an audio system, a television receiver, a radio receiver, or the like is appropriately controlled by controlling the amplification ratio of the built-in amplifier.

1 is a block diagram showing such a conventional audio signal output device.

As shown in FIG. 1, the amplifier 1 receives an audio signal as an input and amplifies and outputs the audio signal.

At this time, the amplifier 1 has an amplification factor proportional to the magnitude of the volume control signal output from the volume control device 4.

The output unit 2 receives an amplified audio signal output from the amplifier 1 and drives the speaker 3 using the amplified audio signal to generate an audible sound signal.

However, such a conventional audio signal output device maintains the magnitude of the volume control signal set in the volume control device 4 at power off, and then determines the magnitude of the audio signal that is applied as it is at power on. do.

If the volume control signal set at the time of power-off is too large, the volume of the audio signal output at the next power-on is so large that the user is very surprised and, in severe cases, the user's hearing may be damaged. .

On the contrary, the volume control signal set at the time of power-off is extremely small, and the volume of the audio signal output at the next power-on also becomes very small.

In such a case, the user cannot distinguish between whether the volume control signal is small in size or whether the reproduced audio signal is inherently small.

Therefore, the present invention controls the size of the audio signal output at power-on of the audio signal output device by an AGC circuit which automatically adjusts the gain so that it is always constant even when there is a change in the input. It is an object of the present invention to provide an output circuit of a two-input audio signal that can be appropriately controlled for each.

The present invention for this purpose automatically controls the gain regardless of the input fluctuation of the filter unit for passing the components of the required bandwidth, such as the high pass component or low pass component of the audio signal input to both sides, regardless of the input variation And an AGC circuit unit for constantly outputting the signal, an amplifying unit for amplifying the signal passing through the AGC circuit unit at a predetermined ratio, and switching means for connecting the audio signals inputted to both of the components to each component by switching. An output circuit of a two-input audio signal is provided.

1 is a block diagram of a conventional conventional audio signal output apparatus.

2 is a block diagram of an audio signal output circuit according to the present invention.

3 is a detailed circuit diagram of FIG. 2.

4A to 4C are characteristic diagrams passing through the filter unit according to the type of filter.

<Description of the symbols for the main parts of the drawings>

100a, 100b: filter section 102a, 102b: AGC circuit section

104a, 104b: amplifier 106: switching means

108: speaker

Hereinafter, the present invention will be described with reference to FIGS. 2 to 4C.

2 is a block diagram of an audio signal output circuit according to the present invention.

3 is a detailed circuit diagram of FIG. 2.

4A to 4C are characteristic diagrams passing through the filter unit according to the type of filter.

First, referring to the basic configuration of the present invention, the filter unit (100a, 100b) for passing the components of the required bandwidth, such as high frequency component or low frequency component of the audio signal input to both sides,

AGC circuit parts 102a and 102b for automatically controlling and controlling the gain of the signal passing through the filter parts 100a and 100b automatically regardless of the input variation;

Amplifying units 104a and 104b for amplifying a signal passing through the AGC circuit units 102a and 102b at a predetermined ratio;

And switching means 106 for connecting the audio signals input to both sides to each of the components by switching.

As the switching means 106, a relay is used.

The filter units 100a and 100b pass components of a required bandwidth among audio signals input to both sides.

The filter units 100a and 100b include a low pass filter (LPF) for passing low pass components, a high pass filter (HPF) for passing high pass components, and a band pass filter (BPF) for passing only a desired band. 4B and 4C show the amplitude characteristics A _(f) of each filter.

Where fc is an important figure representing the filter's characteristics, which is the cutoff frequency and the frequency at which the attenuation is -3 dB.

In the present invention, the filter units 100a and 100b are active filters composed of only a resistor and a capacitor.

The AGC circuits 102a and 102b are automatic gain control circuits that automatically control a gain input from a general audio device so that the magnitude of the output signal does not change even if the magnitude of the input signal changes. .

In other words, the AGC circuits 102a and 102b are circuits that automatically control the gain of the receiver against fluctuations in the input level. The direct current component is used as a control voltage to operate a constant gain.

Since the amplifiers 104a and 104b pass through the AGC circuits 102a and 102b, the gain-controlled signal has a small size, and thus amplifies it at a predetermined ratio.

The amplifiers 104a and 104b are connected by a PNP transistor and an NPN transistor to receive and amplify an audio signal output to drive the speaker 3 to become an audible acoustic signal.

The switching means 106 is a relay for switching the opening and closing in accordance with the input signal is used.

With this configuration, the audio signal inputted to both sides passes the necessary bandwidth component through the filter units 100a and 100b, and the gain is automatically obtained by the AGC circuit units 102a and 102b regardless of the variation of the input signal size. It is controlled and constantly output, and is amplified by the amplifiers 104a and 104b at a predetermined ratio and output to the outside through both speakers 108.

As a result, according to the present invention, audio signals input to both sides can be heard through the speaker 108 on both sides with clean sound quality.

As described above, according to the present invention, the amplitude of the audio signal output at the time of power-on of the audio signal output device is controlled by an AGC circuit which automatically adjusts the gain so that it is always constant even when there is a change in the input. There is an effect that the audio signals input to both sides can be appropriately controlled.

Claims (3)

A filter unit for passing a required bandwidth component such as a high pass component or a low pass component of the audio signal input to both sides, An AGC circuit unit for controlling the gain of the signal passing through the filter unit automatically and constantly outputting the gain regardless of input variation; An amplifier for amplifying the signal passing through the AGC circuit at a predetermined rate; Switching means for connecting the audio signal input to both of the components by switching, An output circuit of a two-input audio signal, characterized in that configured. The output circuit of claim 1, wherein the filter unit is an active filter including a resistor and a capacitor. The output circuit of claim 1, wherein the switching means is a relay.