JPH10136483A - Input/output circuit for acoustic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use one jack for an input and for an output without using a mechanical switch. SOLUTION: An output amplifier 15 is connected to a jack 11. A switch circuit 12 is connected to a signal line between the jack 11 and a recording amplifier 13R. At the reproduction, a transistor Q11 controls the amplifier 15 in its operating state and also turns off the circuit 12, and outputs a sound signal that is outputted from the amplifier 15 to the jack 11. When recording, the transistor Q11 controls the amplifier 15 in its static state, turns on the circuit 12 and inputs a sound signal that is inputted to the jack 11 to the amplifier 13R.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an input / output circuit of an audio device such as a tape recorder.

[0002]

2. Description of the Related Art In audio equipment, for example, a tape recorder, one jack may be used as an input jack for an external microphone and an output jack (monitor jack) for an earphone in order to reduce the size thereof. . In other words, if the connection from the output amplifier to the jack and the connection from the jack to the input amplifier are selectively switched by a switch, the input jack and the output jack can be shared, and the tape recorder can be downsized. .

[0003]

However, in general, the load of an audio equipment has a low impedance and a large load current flows. Therefore, as described above, when one input jack and one output jack are used as a single jack, and when a switch is provided between the output terminal of the output amplifier and the dual-purpose jack, an electronic type having a large on-resistance is used as the switch. Can not use the switch circuit, and must use a mechanical switch.

However, a mechanical switch is a factor that hinders downsizing of the device, and contradicts downsizing of the device by also using the jack.

[0005] The present invention is to solve such a problem.

[0006]

According to the present invention, a first circuit for outputting a first audio signal, a switch element for controlling the operation of the first circuit on / off, a terminal for audio, , A second circuit, and a switch circuit connected to a signal line between the terminal and an input terminal of the second circuit, an output terminal of the first circuit is connected to the terminal,
In the first state, the first circuit is controlled to an operating state by the switch element, and the switch circuit is turned off to output an audio signal output from the first circuit to the terminal. , In the second state,
An audio device in which the first circuit is controlled to be stopped by the switch element and the switch circuit is turned on so that the audio signal input to the terminal is input to the second circuit. It is an input / output circuit. Therefore, the terminal works not only for input but also for output.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a case where the present invention is applied to an input circuit and an output circuit of a tape recorder.

That is, reference numeral 11 denotes a jack for both input and output, into which an external microphone plug is inserted during recording, and an earphone plug is inserted during reproduction. And this jack 11
Are connected to the recording amplifier 13R of the recording / reproducing circuit 13 through the signal line of the resistor R11 → the switch circuit 12 formed into a one-chip IC → the capacitor C11 → the resistor R12 → the capacitor C12. The recording / reproducing circuit 13 has a recording amplifier 13R, a reproducing amplifier 13P, and the like, and is formed as a one-chip IC. A recording / reproducing head 14 is connected to the recording / reproducing circuit 13.

Further, the reproduction amplifier 1 of the recording / reproduction circuit 13
3P is connected to the contact terminal of the jack 11 through the signal line of the capacitor C13 → the variable resistor R13 for adjusting the reproduction volume → the output amplifier 15 formed as a one-chip IC → the capacitor C14. For example, when the control terminal PWR is at the “L” level, the output transistor of the amplifier 15 is turned off, and the operation of the amplifier 15 is stopped.
When the signal is at "H" level, all the transistors of the amplifier 15 are in an operating state and operate as an amplifier.

Reference numeral 16 denotes a microcomputer for controlling the system.
Controls the operation mode of the recording / reproducing circuit 13. Further, the port output Q1 of the microcomputer 16 is supplied as a control signal to the switch circuit 12, and the switch circuit 12 is turned on during recording and turned off during reproduction. Reference numerals K1 to KN are various operation keys.

Further, a battery 17 of, for example, 1.5 V is provided as a power supply, and its output voltage is supplied to the amplifier 15 as its operating voltage, and is boosted directly (not shown) directly or by a DC-DC converter. After that, it is supplied to each part.

Also, a battery 17 and a control terminal of the amplifier 15
Between the PWR and the PWR, the emitter-collector connection of the switching transistor Q11 is connected, and the port output Q2 of the microcomputer 16 is supplied to the base of the transistor Q11. The port output Q2 is at "H" level during recording and at "L" level during reproduction.

In such a configuration, when the recording key among the keys K1 to KN is pressed, the microcomputer 16 sets the recording / reproducing circuit 13 to the recording mode. Also, the port output Q2 of the microcomputer 16 goes to "H" level, turning off the transistor Q11, thereby stopping the operation of the amplifier 15. Therefore, the amplifier 15
Does not output any signal. Further,
The switch circuit 12 is turned on by the port output Q1 of the microcomputer 13.

Therefore, if a plug of a microphone (not shown) is inserted into the jack 11, the audio signal from the plug is transmitted from the jack 11 → the resistor R11 → the switch circuit 12 → the capacitor C11 → the resistor R12 → the capacitor. The signal is supplied to the recording amplifier 13R of the recording / reproducing circuit 13 through the signal line of C12, and further supplied to the head 14. Therefore, the audio signal collected by the microphone is recorded.

At this time, the audio signal from the jack 11 should flow into the output terminal of the amplifier 15.
During recording, since the output transistor of the amplifier 15 is off, the output impedance of the amplifier 15 when viewed from the jack 11 is sufficiently larger than the output impedance of the microphone, and has a large effect on the audio signal from the jack 11. I will not give.

On the other hand, when a reproduction key among the keys K1 to KN is depressed, the microcomputer 16 causes the recording and reproduction circuit 1 to operate.
3 is a recording mode. The switch circuit 12 is turned off by the port output Q1 of the microcomputer 13. Subsequently, the port output Q2 of the microcomputer 16 becomes "L" level, and the transistor Q1
1 is turned on, whereby the amplifier 15 is in an operating state.

Therefore, the reproduction signal of the head 14 is supplied to the jack 11 through the signal line of the reproduction amplifier 13P → the capacitor C13 → the variable resistor R13 → the amplifier 15 so that the plug of the earphone (not shown) is connected to the jack 11. If is inserted, the playback sound can be heard through the earphone.

Thus, in this tape recorder, the input jack of the microphone and the output jack of the earphone are shared by one jack 11, so that the tape recorder can be downsized. Also,
Since the switch circuit 12 switches the jack 11 between the input jack of the microphone and the output jack of the earphone, the size of the tape recorder can be further reduced as compared with the case where a mechanical switch is used.

Further, since the circuit configuration can be simplified, the tape recorder can be further reduced in size and the cost can be reduced in this respect as well.

In the above description, the present invention is applied to a tape recorder. However, the present invention can also be applied to input / output circuits of other audio equipment such as a recording / reproducing apparatus using a mini disc. it can.

[0021]

According to the present invention, since the input terminal and the output terminal are shared by one terminal, the size of the audio equipment can be reduced. In addition, the electronic switch circuit switches the shared terminal between the input terminal and the output terminal, making it possible to further reduce the size of the audio equipment as compared to using a mechanical switch. Can be. Further, since the circuit configuration can be simplified, the acoustic equipment can be downsized from this point,
Costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a connection diagram illustrating one embodiment of the present invention.

[Explanation of symbols]

11 = jack, 12 = switch circuit, 13 = recording / reproducing circuit, 14 = recording / reproducing head, 15 = output amplifier, 16
= Microcomputer, 17 = battery

Claims (2)

[Claims] A first circuit for outputting a first audio signal; a switch element for controlling ON / OFF of an operation of the first circuit; an audio terminal; a second circuit; And a switch circuit connected to a signal line between the first circuit and an input terminal of the second circuit. An output terminal of the first circuit is connected to the terminal. The element controls the first circuit to an operating state, and the switch circuit is turned off to output an audio signal output from the first circuit to the terminal. In the second state, A switch device controls the first circuit to be in a stopped state, and the switch circuit is turned on so that an audio signal input to the terminal is input to the second circuit. Output circuit. 2. The input / output circuit of an audio device according to claim 1, wherein said audio device is a recording and reproducing device, said first circuit is a reproducing circuit, and said second circuit is a recording circuit. An input / output circuit of an audio device in which a microphone plug is connected to the terminal during recording, and an earphone plug is connected to the terminal during reproduction.