JPH09307990A - Signal input output circuit for audio equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the equipment small and to prevent mis-plug-in of a headphone or a microphone by using one connection jack in common for a connection jack for a stereo headphone and a connection jack for a monaural microphone in an audio equipment such as a tape recorder. SOLUTION: In the case of connection to a stereo headphone, a signal from a headphone right channel signal amplifier 2 is given to a control transistor(TR) 3 via an amplifier 5 and a DC transformation circuit 6 to make the TR 3 conductive and also a 1st switching TR 1 nonconductive and a 2nd switching TR 2 conductive thereby blocking a signal input to a microphone input signal amplifier 4. In the case of connection to a monoral microphone, the 2nd switching TR 2 and the control TR 3 are made nonconductive so as to make the 1st switching TR 1 conductive, then an output signal from a head phone left channel signal amplifier 3 is not inputted to the microphone input signal amplifier 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal input / output circuit in audio equipment such as a tape recorder.

[0002]

2. Description of the Related Art Conventionally, in audio equipment such as a tape recorder, a connection jack for connecting a headphone and a connection jack for connecting a microphone are usually provided separately.

This is because the connection jack for connecting the headphones is for outputting a signal and the connection jack for connecting the microphone is for inputting a signal. Is exactly the opposite.

[0004]

However, since it is necessary to provide two connection jacks, it not only hinders downsizing of the device but also a connection jack for connecting headphones and a connection jack for connecting a microphone. There is also a risk of incorrect insertion due to the similar appearance.

[0005]

In order to solve the above problems, the present invention provides a first signal amplifying means for amplifying a left channel signal, a second signal amplifying means for amplifying a right channel signal, and the first signal. A connection jack including a first terminal to which a signal output from the amplifying means is guided, a second terminal to which a signal output from the second signal amplifying means is guided, and a third terminal whose one end is grounded, and the connection. Input signal amplifying means for amplifying a signal inputted from the outside through the jack for use, DC voltage converting means for converting the signal output from the first signal amplifying means into DC voltage, and output by the DC voltage converting means. Control switching means controlled by a signal,
The first switching means is controlled by the control switching means and controls transmission of a signal output from the second amplifying means to the first terminal; and is controlled by a DC voltage output by the DC voltage converting means. It is intended to provide a signal input / output circuit of an audio device, which is provided with a second switching means for controlling the transmission of the signal output from the two amplification means to the input signal amplification means.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings.

First, FIG. 1 is a circuit block diagram showing a configuration of an audio device to which the present invention is applied. And FIG.
Shows the configuration of the connection jack portion of the stereo headphones (a) and the monaural microphone (b) used in the audio device of the present invention.

In FIG. 2, in the stereo headphones,
A left channel input terminal L, a right channel input terminal R, and a ground terminal G1 are provided from the tip of the connecting male jack 7, and a monaural microphone is provided with an output terminal O and a ground terminal G2 from the tip of the connecting male jack 8. Thus, in stereo headphones, the connecting male jack 7 has three conductor portions, and in a monaural microphone, the connecting male jack 8 has two conductor portions.

Next, referring to FIG. 1, reference numeral 1 is a connecting female jack into which the connecting male jack 7 of the stereo headphones or the connecting male jack 8 of the monaural microphone is inserted, and the terminal A is the connecting male jack 7. Connected to the left channel input terminal L or the output terminal O of the connecting male jack 8, the terminal B is connected to the right channel input terminal R of the stereo headphones or the ground terminal G2 of the monaural microphone, and the terminal C is the ground terminal of the stereo headphones. Connect to G1 or the ground terminal G2 of the monaural microphone.

Reference numeral 2 is a headphone right channel signal amplifier, 3 is a headphone left channel signal amplifier,
Reference numeral 4 is a microphone input signal amplifier, and Tr1 is a first for controlling the output signal of the headphone left channel signal amplifier 3.
A switching transistor, Tr2 is a second switching transistor that controls an input signal to the microphone input signal amplifier 4, and Tr3 is the first switching transistor Tr1 and the second switching transistor Tr.
2 is a control transistor for controlling 2.

Further, 5 is a signal amplifier provided in parallel with the signal output path of the headphone right channel signal amplifier 2, and 6 is a DC conversion circuit for converting the output signal of the signal amplifier into a DC voltage. The output of 6 is connected to the base of the control transistor Tr3 and the base of the second switching transistor Tr2.

Further, a + 5V DC power source is connected to the base of the first switching transistor Tr1.

Next, the operation of the circuit shown in FIG. 1 will be described.

First, when nothing is connected to the connecting female jack 1, the output signal from the headphone right channel signal amplifier 2 is transmitted to the signal amplifier 5, and the output signal of the signal amplifier 5 is the DC conversion circuit 6. Is output as a DC voltage.

Since the DC voltage output from the DC conversion circuit 6 is applied to the bases of the second switching transistor Tr2 and the control transistor Tr3, the second switching transistor Tr2 and the control transistor Tr3 are turned on.

When the second switching transistor Tr2 is turned on, the input signal path to the microphone input signal amplifier 4 is grounded, so that the output signal from the headphone left channel signal amplifier 3 is input to the microphone input signal amplifier 4. Not entered.

Next, as shown in FIG.
When the male jack 7 for connecting the stereo headphones shown in (b) is connected, the terminal A and the left channel input terminal L are connected, and the terminal B and the right channel input terminal R are connected, so that the terminal B is connected. Will be connected to the impedance of stereo headphones.

Here, when a signal is output from the headphone right channel signal amplifier 2, this signal is transmitted to the right channel input terminal R of the connecting male jack 7 and
The signal is also transmitted to the signal amplifier 5, and the output signal from the signal amplifier 5 is output from the DC conversion circuit 6 as a DC voltage.

The DC voltage output from the DC conversion circuit 6 is applied to the bases of the second switching transistor Tr2 and the control transistor Tr3.
The switching transistor Tr2 and the control transistor Tr3 are turned on.

When the second switching transistor Tr2 is turned on, the input signal path to the microphone input signal amplifier 4 is grounded, so that the output signal from the headphone left channel signal amplifier 3 is sent to the microphone input signal amplifier 4. Not entered.

When the control transistor Tr3 is turned on, no voltage is applied to the base of the first switching transistor Tr1 and the first switching transistor Tr1 is turned off. Therefore, the headphone left channel signal amplifier is no longer used. The signal output from 3 is no longer grounded.

In this way, the signal output from the headphone right channel signal amplifier 2 is transmitted to the right channel input terminal R of the connecting male jack 7, and the signal output from the headphone left channel signal amplifier 1 is connected. Since the signal is transmitted to the left channel input terminal L of the male jack 7, the user can listen to the audio signal from the stereo headphones.

Further, the female jack 1 for connection has the structure shown in FIG.
When the connecting male jack 8 of the monaural microphone shown in (b) is connected, the terminal A is connected to the output terminal O, and the terminals B and C are connected to the ground terminal G2.

Since the terminal B is grounded in this manner, even if there is a signal output from the right channel input terminal R, it is grounded without being input to the signal amplifier 5, and the DC at the latter stage of the signal amplifier 5 is connected. Since the conversion circuit also outputs nothing, a voltage is not applied to the base of the control transistor Tr3 and the control transistor Tr3 is turned off.

When the control transistor Tr3 is turned off, the + 5V voltage from the DC power supply is applied to the base of the first switching transistor Tr1 and the first switching transistor Tr1 is turned on. Therefore, even if there is a signal output from the headphone left channel signal amplifier 3, it will not be guided to the terminal A of the connecting female jack 1 and the microphone input signal amplifier 4. In this state,
The audio signal output from the monaural microphone is input to the microphone input signal amplifier 4.

[0026]

As described above in detail, according to the present invention, the first signal amplifying means for amplifying the left channel signal, the second signal amplifying means for amplifying the right channel signal, and the first signal amplifying means. And a connection jack having a first terminal to which a signal output from is output, a second terminal to which a signal output from the second signal amplification means is input, and a third terminal whose one end is grounded, and the connection jack. An input signal amplifying means for amplifying a signal inputted from the outside via a DC voltage converting means for converting the signal outputted by the first signal amplifying means into a DC voltage; and a signal outputted by the DC voltage converting means. A controlled switching means that is controlled; a first switching means that is controlled by the controlling switching means and that controls transmission of a signal output from the second amplifying means to the first terminal; Since it is provided with the second switching means which is controlled by the DC voltage output from the voltage converting means and controls the transmission of the signal output from the second amplifying means to the input signal amplifying means, the monaural microphone and the stereo headphone are combined into one. Can be shared with the connection jack.
Therefore, it not only contributes to the miniaturization of the device, but also does not insert the microphone or headphone by mistake.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing a configuration of the present invention.

FIG. 2 is a diagram showing a configuration of a male jack for connecting stereo headphones and a monaural microphone.

[Explanation of symbols]

 1 Connection female jack 2 Headphone right channel signal amplifier 3 Headphone left channel signal amplifier 4 Microphone input signal amplifier 5 Signal amplifier 6 DC conversion circuit 7 Connection male jack 8 Connection male jack A terminal B terminal C terminal G1 Ground Terminal G2 Ground terminal L Left channel input terminal O Output terminal R Right channel input terminal Tr1 First switching transistor Tr2 Second switching transistor Tr3 Control transistor

Claims (1)

[Claims] 1. A first signal amplifying means for amplifying a left channel signal, a second signal amplifying means for amplifying a right channel signal, a first terminal to which a signal output from the first signal amplifying means is guided, and A connection jack including a second terminal to which a signal output from the second signal amplification means is guided, and a third terminal whose one end is grounded, and an input for amplifying a signal input from the outside through the connection jack Signal amplifying means, direct current voltage converting means for converting the signal output from the first signal amplifying means into direct current voltage, control switching means controlled by the signal output from the direct current voltage converting means, and the control switching Means for controlling the transmission of the signal output from the second amplifying means to the first terminal, and a DC voltage output by the DC voltage converting means. Is controlled by the signal input and output circuit of the audio equipment in which the second amplifying means is characterized in that a second switching means for controlling the transmission of the input signal amplification means of the signal output.