JPS649768B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention provides a portable FM device that has two stereo amplifiers and a stereo output jack, but only one built-in speaker.
This invention relates to amplification devices used in radios and the like.

Conventional configuration and its problems In small portable FM radios, FM
Even if it is possible to receive stereo broadcasts, it is not possible to install two sets of stereo speakers with the necessary distance between them, so only one set of speakers is built in, and stereo sound is transmitted using a stereo headphone. Many of them are designed so that they can only be played back. Additionally, most of these small radios are generally powered by dry batteries.

However, in this type of conventional device, a separate manual switch must be installed to switch the input signal to the amplifier circuit for monaural playback using the built-in speaker and stereo playback using the stereo headphone. Furthermore, even during monaural playback, power is supplied to both sets of stereo amplifier circuits, resulting in a short battery life.

OBJECT OF THE INVENTION The present invention solves these conventional drawbacks and allows the input signal of the amplifier circuit to be switched between stereo and monaural by simply inserting the plug of the stereo headphone into the jack, while reducing power consumption. It is an object of the present invention to provide a device that can reduce battery life and extend battery life without hindering miniaturization of portable receivers.

Structure of the Invention The present invention uses three sets of switch circuits that are switched in conjunction with each other when a plug such as a stereo headphone is inserted into a stereo output jack. Power is supplied to only one of the two sets of amplifier circuits for operation, the output of the one amplifier circuit is applied to the speaker, and two stereo input signals are both applied to the one amplifier circuit. I'm trying to play it back in monaural.

DESCRIPTION OF EMBODIMENTS In FIGS. 1 and 2, an embodiment of the present invention is shown, 1 and 2 are first and second input terminals to which stereo audio signals are added, respectively, and 3 and 4 are first and second input terminals. , first and second amplification circuits for stereo amplification coupled to the second input terminal via variable resistors 5 and 6 for volume adjustment; 7 is the first and second amplification circuits 3 and 4; A stereo audio signal output jack 8 connected to the output side has one built-in speaker, 9 a battery as a power source, and 10 a power switch. Furthermore, 11, 12, and 13 are first, second, and third switch circuits that are switched in conjunction with the insertion of the stereo headphone plug into the jack 7, and in the embodiment shown in FIG. It is shown as a mechanical switch mechanically coupled to jack 7.

With this configuration, if no plug is inserted into the jack 7, the switches 11 and 1
2 and 13 are switched to the a side, and the first switch 1
1, the output side of the first amplifier circuit 3 is coupled to the built-in speaker 8, and the audio signal applied to the second input terminal 1 by the second switch 12 is also applied to the first input terminal 1. Since the switching is made so that the signal is mixed with the audio signal and applied to the first amplifier circuit 3, even if stereo audio signals are applied to the input terminals 1 and 2, they are mixed and converted into a monaural audio signal and sent to the amplifier circuit 3. The signal is amplified and reproduced by the speaker 8. Moreover, at this time, the power supply to the second amplifier circuit 4 is stopped by the third switch 13, so there is no unnecessary power consumption in the second amplifier circuit 4, which is unnecessary for monaural reproduction, and the power consumption is reduced. can be reduced and the life of the battery 9 can be extended.

On the other hand, when the plug is inserted into the jack 7, the first, second, third switch circuits 11, 12,
13 is switched to the b side, the supply of the audio signal to the speaker 8 is cut off, and the stereo audio signal is supplied only to the headphone from the jack 7. Also, the second switch circuit 12 is opened, so that the input signal is cut off. The stereo audio signals applied to terminals 1 and 2 are applied independently to amplifier circuits 3 and 4, respectively.
Furthermore, power is supplied to the second amplifier circuit 4 by the third switch circuit 13, and a stereo reproduction state is established.

In this way, it is possible to switch between the monaural playback state and the stereo playback state simply by inserting or not inserting the stereo headphone plug into the jack 7, so there is no need to provide a separate manual switch, simplifying the configuration. It can be made inexpensively, and the operability can be greatly improved. Furthermore, during monaural playback, only the first amplifier circuit 3 is operated and the power supply to the second amplifier circuit 4 is stopped, so power consumption can be reduced and a battery is used as the power source. Even if it is, its lifespan can be extended.

However, in the case shown in Fig. 1,
Since there are three switch circuits, which are mechanical switch circuits, and all of these circuits are linked to the insertion of the plug into the jack 7, the mechanical structure becomes complicated, and the space occupied by the mechanical switches makes it difficult to carry. There remains the problem that miniaturization of the receiver is hindered.

An example that does not hinder miniaturization will be shown below using FIG. In this example, the second
The switch circuit 12 is composed of a transistor 14 and a resistor 1.
5 and 16 and coupling capacitors 17 and 18, and when the third switch circuit 13 is switched to the a side (monaural side), the power is supplied to the transistor 14 via the third switch circuit 13. Input terminal 2 by supplying
The audio signal applied to the input terminal 1 is also applied to the first input terminal 1 side. In this way, the number of mechanical switches can be reduced. As a result, the mechanical connection structure can be simplified, and the intended purpose can be achieved without hindering miniaturization of the entire device.

Effects of the Invention As described above, according to the present invention, the input circuit, amplifier circuit, and speaker circuit can be set to stereo by simply inserting a plug for stereo playback such as a stereo headphone into a jack for outputting stereo audio signals. To provide a device with a simple configuration and low cost that can automatically switch between audio and monaural audio and has good operability. Also, by using one switch for two loads, the space efficiency decreases despite the addition of new functions compared to the conventional manual switch for stereo/monaural switching. Therefore, miniaturization of portable type devices is not hindered.
Furthermore, power consumption can be reduced by stopping the power supply to one of the unnecessary amplifier circuits in the monaural reproduction state. Further, power consumption is reduced, and by providing a matrix switch circuit instead of mechanical means, it is easy to integrate the device into an integrated circuit, and further miniaturization can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an amplifying device proposed by the inventors of the present invention, which is the basis of the present invention, and FIG. 2 is a circuit diagram of an amplifying device according to an embodiment of the present invention. 1, 2...first and second input terminals, 3, 4...
First and second amplifier circuits, 7... Jack, 8...
Speakers, 11, 12, 13...first, second, third switch circuits.

Claims (1)

[Claims] 1: first and second input terminals to which first and second audio signals are applied; a first amplifier circuit whose input sides are coupled to the first and second input terminals, respectively, and which is constantly supplied with power; a second amplifier circuit selectively supplied with power; a stereo output jack coupled to the output sides of the first and second amplifier circuits; and a stereo output jack coupled to the output side of the first amplifier circuit. a first mechanical switch circuit that is switched in conjunction with the insertion of a plug into the jack and connects the output side of the first amplifier circuit and the speaker only when the plug is not inserted;
The audio signal applied to the second input terminal is also transmitted to the first input terminal only when the plug is not inserted.
A matrix switch circuit consisting of a transistor added to the amplifier circuit of a second machine which also supplies power to the amplifier circuit of the above, and whose connection is switched to the second terminal side of the output only when the above plug is not inserted, and supplies power to the transistors forming the above matrix switch circuit; An amplifier device equipped with a switch circuit.