JPS58171194A - Acoustic device - Google Patents

Abstract

PURPOSE:To reduce the titled device at its size and to attain stereophonic reproducing, by performing monaural reproducing from a speaker without using a stereophonic headphone and stereophonically reproducing FM stereophonic broadcating at the use of the stereophonic headphone. CONSTITUTION:A voice signal supplied to right and left voice amplifier circuits 7, 8 is amplified and outputted to a stereophonic headphone jack 24. When a stereophonic headphone plag is connected to the jack 24, the stereophonic headphone is driven by the outputs of the voice amplifier circuits 7, 8. When said plag is disconnected from the headphone, the outputs of the circuits 7, 8 are composed by load resistors 21-23 and applied to a speaker 19 through a voice amplifier circuit 18.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an audio device, and more particularly to a television receiver having one speaker and an FM stereo radio section.

In recent years, the miniaturization of television receivers has progressed further, and for example, black and white television receivers using a 1.6-inch cathode ray tube and color television receivers using a 3-inch color cathode ray tube have appeared. When installing an FM stereo radio section in such a small television receiver, there is a strong demand for miniaturization, which means that only one speaker can be placed, or even two speakers. In any case, only one speaker could be installed, because even if the speakers were placed, they could not be placed at a sufficient distance from each other and a stereo effect could not be obtained.

The present invention provides such a small television receiver with only one speaker installed in the receiver body, and on the other hand, equipped with stereo headphones, and provided with a jack part to which the stereo headphones can be connected, When stereo headphones are not used, monaural reproduction is performed from the speakers, and when stereo headphones are used, FM stereo broadcasts are reproduced in stereo.

An example of this will be described below with reference to FIGS. 1 and 2.

First, in FIG. 1, 1 is a TV audio detection circuit, 2a,
2b is a radio stereo demodulation circuit, and each demodulated output signal is divided into input signals of left and right audio amplifier circuits 7.8 by audio signal switching diodes 3, 4, and 5.5.

Here, 9,1o.

11 is a junction capacitor, 12, 13.degree. 14 is a resistor for applying bias current to the diodes 3, 4, 5.6, and 15, 16 is a load resistance of the diode 3.degree.4.5.6.

Further, 17 is a radio-television changeover switch, which allows the television audio detection circuit 1 and the radio stereo demodulation circuit 2 to
It selectively supplies power supply voltage to a and 2b, and controls conduction and cutoff of diodes 3, 4, 5, and 6. 18 is an audio amplification circuit, 19 is a speaker, 20 is a DC power supply, 21
, 22, 23 are load resistors, and 24 is a stereo phone jack, which connects the output terminals of the left audio amplifier circuits 7', 8 and the input terminal of the audio amplifier circuit 18 via load resistors 21, 22, 23. When the stereo headphone plug is not inserted and connected, the contacts A and C are connected.
-d is closed, and the output end of the audio amplification circuit 7.8 is connected to the input end of the audio amplification circuit 18. In addition, 25 is a forced monaural switch, and when it is closed, the demodulation circuits 2a and 2b are
is played back in monaural.

In the above configuration, when the radio-television changeover switch 17 is connected to the radio side terminal R, the radio stereo demodulation circuit 2. Power is supplied to a and 2b, and the resistor 13
．． The switching diode 6.6 is made conductive through 14. This bias current generates a potential difference across the load resistor 16, 16, and the switching diode 3-4 on the TV audio detection circuit 1 side becomes reverse biased, and the TV audio detection circuit 1 is disconnected from the audio amplifier circuits 7 and 8. be separated.

That is, the output audio signals of the radio stereo demodulation circuits 2a and 2b are input to the left and right audio amplification circuits 7 and 8. Note that even if the forced monaural playback state 25 of the radio stereo demodulation circuits 2a, 2b is closed and the forced monaural playback state 25 is set to the monaural playback state, the outputs of the stereo demodulation circuits 2a, 2b are simply made equal, and the operation is exactly the same as in the above case.

On the other hand, when the radio-TV changeover switch 17 is connected to the TV side terminal T, the switching diodes 3 and 4 are conductive, and the switching diodes 5 and 6 are cut off, and the audio output signal of the TV audio detection circuit 1 is is input to the audio amplification circuits 7 and 8.

In this way, the audio signals supplied to the left and right audio amplification circuits 7 and 8 are amplified, and the stereo headphone jack 24
is output to. This stereo headphone jack 24
When the plug 27 of the stereo headphones 26 shown in FIG.
Since the plug 27 is connected to the contacts a and d, the audio amplification circuits 7 and 8 are disconnected from the audio amplification circuit 18, and the outputs of the audio amplification circuits 7 and 8 are connected to the TV audio signal and the audio amplification circuit 18. A radio monaural signal is played back in monaural, and a radio stereo signal is played back in stereo. When the plug 27 of the stereo headphones 26 is connected to the jack 24, the audio output signals of the left and right audio amplification circuits 7 and 8 are combined by the load resistor 21°22.23. The signal is input to the audio amplification circuit 18. The audio signal amplified by the audio amplification circuit 18 is applied to a speaker 19 and is reproduced monaurally as an audio signal.

In FIG. 2, 28 is a cathode ray tube, 29 is a channel selection knob, 30 is a volume adjustment knob, and 31 is an indicator.

As described above, according to the present invention, it is possible to perform stereo reproduction by using stereo headphones when necessary, without sacrificing the small size function that is the greatest feature of the ultra-1JS type television receiver.

In addition, there is no need to add a changeover switch or use a special headphone jack to switch between stereo headphone playback and built-in speaker playback, and there is a high degree of freedom in the number and placement of various operation parts in product design, allowing for miniaturization. It also has the advantage of having fewer restrictions.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an audio device according to an embodiment of the present invention,
FIG. 2 is an external perspective view of the device.゛1...
TV audio detection circuit, 2a, 2b... Radio section stereo demodulation circuit, 3, 4, 5.6... Switching diode, 7, 8.18... Audio amplification circuit ,1
7...Radio-TV selector switch, 19.-
...Speaker, 20...DC power supply, 24.
-... Stereo headphone jack, 26...
・Stereo headphones. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] A left and right audio amplification device comprising a television audio detection circuit and an FM stereo radio section, and one speaker, and is commonly used for the audio signals output from the television audio detection circuit and the FM stereo radio section. A circuit is provided to supply audio output signals from these audio amplification circuits to the beaker via a stereo headphone jack, and stereo headphones are connected to the stereo headphone jack to reproduce stereo FM stereo broadcasts. The sound equipment that made this possible.