JPS622513B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an audio multiplex television receiver with low power consumption.

In recent years, as television has become more popular, there has been a demand for more diversification and higher quality broadcast programs. Audio multiplex television broadcasting has been proposed as a means of making such more advanced programs possible, and its practical use is becoming increasingly popular.

The audio multiplexing of television broadcasting can be thought of as a technology that evolved from the stereo broadcasting technology of FM radio broadcasting, but it takes advantage of the characteristics of television to not only provide stereo audio, but also allows two different types of audio to be simultaneously transmitted in parallel. It is now possible to arbitrarily switch between the sending and receiving sides to receive only one or both at the same time, making it possible to add a new program format called a so-called bilingual broadcast program to television broadcast programs. Ta.

For this reason, it has become essential for television receivers to be equipped with a reception function that can support the audio multiplexing of this program. FIG. 1 shows an example of a television receiver having the function of receiving such audio multiplexed television broadcasts.

FIG. 1 shows only an audio signal processing circuit compatible with audio multiplexing of a television receiver, and other parts are omitted.

In the figure, 6 is a transistor constituting a buffer amplifier, and 1 to 5 are resistors and capacitors therefor. 7 is a capacitor for DC cutoff, 8, 9
10 is a main channel amplification circuit, 11 is a stereo matrix circuit, 12 is a switching circuit that switches between monaural, stereo, and bilingual broadcasting, and 13 is a sub channel. A bandpass filter for extracting the signal, 14 an amplification/detection circuit for the sub-channel, 15 an amplification/detection circuit for the pilot signal, 16 a 922.5Hz mechanical filter, 17 a pilot for discriminating bilingual broadcast information. Signal amplification/rectification circuit, 18 is a switch drive circuit for two-language broadcasting, 19 is a 982.5Hz mechanical filter, 20 is a pilot signal amplification/rectification circuit for discriminating stereo broadcast information, 21 is a switch drive circuit for stereo broadcasting 22 is Left channel audio output circuit, 23 is right channel audio output circuit, 24
25 is a power supply terminal, and 25 is an audio multiplex signal input terminal from an audio demodulation circuit of the television receiver.

Next, the operation will be explained.

The audio signal supplied to the input terminal 25 from the audio demodulation circuit of the television receiver is taken out to the emitter of a transistor 6 for buffer amplification, and the main channel signal is frequency-corrected by a de-emphasis circuit consisting of a resistor 8 and a capacitor 9. The signal is then supplied to the main channel amplifier circuit 10 and amplified to a predetermined level to obtain a main channel audio signal.

At the same time, a sub-channel carrier wave is extracted from the audio signal by the emitter of the transistor 6 and frequency-modulated with the sub-channel audio signal by the bandpass filter 13, and the sub-channel carrier wave is extracted from the audio signal by the sub-channel amplification/detection circuit 14. is obtained.

In addition, the output of this bandpass filter 13 is a pilot signal [a signal whose frequency is 3.5 times the horizontal synchronization frequency as a carrier wave, and which is amplitude-modulated with a pilot signal for information discrimination (signal of 922.5Hz or 982.5Hz)]. Since the pilot signal is also extracted, this pilot signal is supplied to the pilot signal amplification/detection circuit 15, and the pilot signal for information discrimination is obtained at its output.

The main channel audio signal output from the main channel amplifier circuit 10 is supplied to the matrix circuit 11 and the switch circuit 12, and the sub channel audio signal from the sub channel amplifier/detector circuit 14 is also supplied to the matrix circuit 11 and the switch circuit 12. has been done. Therefore, a total of four types of audio signals are input to the input of the switch circuit 12: the main channel audio signal, the sub-channel audio signal, and the two channel audio signals from the matrix circuit 11.

In addition, the pilot signal for information discrimination, which is the output of the pilot signal amplification/detection circuit 15, is 922.5
Hz mechanical filter 16 and 982.5 Hz mechanical filter 19, and when the pilot signal for information discrimination is a 922.5 Hz signal, this signal is taken out as the output of the filter 16, and converted into DC by the amplification/rectification circuit 17. After that, the switch circuit 12 is driven through the switch drive circuit 18 for two-language broadcasting, and the main channel audio signal from the amplifier circuit 10 is sent to the left channel audio output circuit 22, and the sub-channel audio signal from the amplification/detection circuit 14 is sent to the left channel audio output circuit 22. The switch circuit 12 is switched so that the information is supplied to the right channel audio output circuit 23, and when the pilot signal for information discrimination is a 982.5Hz signal, this signal is taken out to the output of the filter 19, and is output to the amplification/rectification circuit 20 and the stereo. Broadcast switch drive circuit 21
The switch circuit 1 drives the switch circuit 12 via the matrix circuit 11 so that the left and right channel audio signals from the matrix circuit 11 are supplied to the left channel and right channel audio output circuits 22 and 23.
Switch 2.

When neither of the drive circuits 18 and 21 is supplying a drive signal to the switch circuit 12, that is, there is no subchannel carrier wave in the audio signal supplied to the input terminal 25, and therefore the pilot signal is When the switch circuit 12 is not present, the switch circuit 12 is switched so as to equally supply the main channel audio signal from the main channel amplifier circuit 10 to both the left channel and right channel audio output circuits 22 and 23. ing.

Therefore, when the channel selected by the television receiver is a bilingual broadcast program, the pilot signal for information discrimination is 922.5Hz, so the drive circuit 18 drives the switch circuit 12,
The main channel audio signal (for example, an audio program in Japanese) from the amplifier circuit 10 is sent to the left channel audio output circuit 22 and then to the amplification/detection circuit 14.
The sub-channel audio signals (for example, an audio program in a foreign language) from the right channel audio output circuit 23 are supplied to the right channel audio output circuit 23, respectively.

Further, in the case of a stereo broadcast program, the pilot signal for information discrimination is transmitted to the amplifier circuit 10 by the driving circuit 21 switching the switch circuit 12 at 982.5 Hz.
The main channel audio signal which is the output of
a sum signal of stereo signals (L+R signal) and a sub-channel audio signal which is the output of the amplification/detection circuit 14;
That is, the difference signal (LR signal) of stereo signals
The left channel and right channel audio signals from the matrix circuit 11, which receives as input, are output to left channel and right channel audio output circuits 22 and 23, respectively.
will be supplied to

When the audio program is not multiplexed, since there is no pilot signal, neither of the drive circuits 18 and 21 generates an output, and the switch circuit 12 outputs the audio signal from the main channel amplifier circuit 10 as it is to both audio signals. Output circuits 22, 23
to reproduce normal non-multiplexed audio signals.

In this way, in a conventional television receiver having an audio multiplex television broadcast reception function, the operation is automatically switched to stereo or bilingual playback mode according to the audio program of the channel selected and received. You can fully enjoy audio multiplexed television broadcast programs,
It is possible to respond to the diversification and sophistication of television broadcast programs.

By the way, even though television broadcast programs have become more diverse, it does not necessarily mean that audio programs will not be multiplexed, or that ordinary audio program broadcasts will all disappear, but that they will all coexist. Therefore, it is thought that a considerable portion of programs without audio multiplexing will continue to exist in the future.

However, in the conventional audio multiplexing television receiver as explained in FIG. All of the representative audio multiplex signal demodulation processing circuits are in operation.

The circuits consisting of these parts are circuits that do not need to operate when the broadcast program being received is a program that is not multiplexed with audio, and as mentioned above, there are many broadcast programs that are not multiplexed with audio. In the situation where
The wasteful power consumption by these circuits during reception of such broadcasts has been a major drawback of conventional audio multiplexed television receivers. Furthermore, this drawback has become a drawback that cannot be overlooked, especially in television receivers powered by dry batteries, car batteries, or the like.

SUMMARY OF THE INVENTION An object of the present invention is to provide an audio multiplexing television receiver that eliminates the drawbacks of the prior art described above and always maintains an appropriate power consumption state depending on the audio multiplexing state of the program being received. .

In order to achieve this object, the present invention is characterized in that the type of audio program of the received channel is detected and the audio signal demodulation processing circuit is controlled accordingly.

An embodiment of the present invention will be described below with reference to FIG. 2 of the drawings.

In the embodiment shown in FIG. 2, the same or equivalent parts as in the conventional example shown in FIG. 1 are given the same numbers. That is, the parts from the resistor 1 to the input terminal 25 are the same in FIG. 2 and FIG. 1.

In FIG. 2, 26 is a transistor for subchannel carrier wave amplification, 27 is a coupling capacitor,
28 to 31 are resistors for operating the transistor 26, 32 is a bypass capacitor, 33 is a coupling capacitor, 34 and 35 are rectifier diodes,
36 is a smoothing capacitor, 37 is a relay driving transistor 40 is a relay, 41 is a resistor, 42 is a capacitor, 43 to 50 are contacts of the relay 40, 51
is the detection circuit. In addition, in this FIG. 2, all contacts 43 to 50 of the relay 40 are at the contact positions when the relay 40 is operated. That is, when the relay 40 operates, the contact 43 closes to 44, and the amplifier circuit 1 constituting the audio multiplex signal demodulation processing circuit
0, matrix circuit 11, switch circuit 12, amplification/detection circuit 14, 15 amplification/rectification circuit 17, 20
Power is supplied for operation to the switch drive circuits 18 and 21 to bring these circuits into operation, and the contacts 45 and
48 is closed to contacts 46 and 50, and the inputs of the left channel and right channel audio output circuits 22 and 23 are connected to the output of the switch circuit 12. Further, in this embodiment, the portion consisting of the input terminal 25 of the buffer amplifier consisting of the transistor 6, the main channel amplifier circuit 10, the matrix circuit 11, the switch circuit 12, and the audio output circuits 22 and 23 is used as an audio signal processing circuit. .

Next, the operation of this embodiment will be explained.

When the audio signal supplied from the television receiver to the input terminal 25 is of a bilingual or stereo audio multiplexed program, a subchannel carrier wave appears at the output of the bandpass filter 13.

Therefore, this sub-channel carrier wave is supplied to the base of the transistor 26 via the capacitor 27, an amplified output appears at the collector, and the output is voltage-doubled and rectified by the capacitor 33 and diodes 34 and 35, and becomes a positive DC voltage. As a result, it is supplied to the base of transistor 37. As a result, the transistor 37 becomes conductive, so the relay 40
A current flows from the power supply terminal 24 through the resistor 41, and the contacts 43 to 50 are closed to the state shown in the figure, resulting in an operating state corresponding to the audio multiplexing program.

Further, when the audio signal supplied to the input terminal 25 is not a signal of an audio multiplexing program, no subchannel carrier wave appears at the output of the bandpass filter 13. Therefore, the base of transistor 37 is maintained at ground potential through resistor 38, so it remains non-conductive, and relay 40 also remains inactive. When the relay 40 is inactive, its contacts 43 to 50 are closed in the opposite direction to that shown, so the contacts 43 are separated from the circuits 10 to 12, 1 forming the audio multiplex signal demodulation processing circuit.
5, 17, 18, 20, and 21 are not supplied with power and are rendered inactive. Furthermore, the contact point 45 is 46
The contact 48 is 47 away from 50 and the contact 48 is 47 away from 50.
9 respectively, and an audio signal is directly supplied to the inputs of the audio output circuits 22 and 23 of the left and right channels from the emitter of the transistor 6 constituting the buffer amplifier via the resistor 8 constituting the de-emphasis circuit. An audio signal that has not been audio multiplexed will be played back.

As described above, in the present invention, the detection circuit 51 detects the sub-channel carrier included in the audio signal from the audio signal of the television signal only in the audio multiplex program, and thereby performs the audio multiplex signal demodulation process. Since the power supply to the circuit is controlled and the audio signal processing circuit consisting of the section from the input terminal 25 to the audio output circuits 22 and 23 is switched depending on the processing of multiplexed signals and non-multiplexed signals, the reception Even when the programmed program is not an audio multiplexing program, power is supplied to the audio multiplexed signal demodulation processing circuit and unnecessary power is not consumed, thereby eliminating the drawbacks of the prior art.

This audio multiplex signal demodulation processing circuit usually includes a very large number of active elements and consumes a considerable amount of power, so the power consumption reduction effect of the present invention is quite large, and when operated with dry batteries etc. It is also possible to extend the usage time and achieve effects suitable for the energy-saving era.

In the embodiment of the present invention shown in FIG. 2, the input of the detection circuit 51 is connected to the output of the band puff filter 13 and is configured to detect the sub-channel carrier wave. In order to achieve this, the configuration may be configured to detect either a pilot signal or a pilot signal for information discrimination, and there is no need for any particular limitation.

In addition, switching of the audio signal processing circuit is also performed using the relay 40.
It should be understood that the switch circuit 12 can be used instead of the contacts 45 to 50, and that FIG. 2 is only one embodiment.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram of a conventional audio multiplex television receiver, and FIG. 2 is an electrical circuit diagram of an audio multiplex television receiver according to an embodiment of the present invention. 10... Main channel amplifier circuit, 11... Matrix circuit, 12... Switch circuit, 13...
Bandpass filter, 14...Amplification/detection circuit for sub channel, 15...Amplification/detection circuit for pilot signal
Detection circuit, 18... 2 Japanese language broadcasting switch drive circuit, 21... Stereo switch drive circuit, 2
2... Left channel audio output circuit, 23... Right channel audio output circuit, 40... Relay for switching power supply and audio signal processing circuit, 43-50... Contact of relay 40, 51... Detection circuit.

Claims (1)

[Claims] 1. In a television receiver having an audio multiplex television broadcast reception function, a detection circuit that detects a sub-channel carrier signal, a pilot signal, or a pilot signal for information discrimination from the output of an audio signal demodulation circuit and generates an output; A switching circuit is provided which is driven by the output of the circuit and controls supply and cutoff of power to the audio multiplex signal demodulation processing circuit and switching of the audio processing circuit. 1. An audio multiplex television receiver characterized in that the power supply to the multiplex signal demodulation processing circuit is cut off.