JPH0691638B2 - Audio multiple signal control circuit - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio multiplex signal control circuit used in a television broadcast receiver or the like.

2. Description of the Related Art In recent years, in television broadcasting, audio multiplex broadcasting has been used for bilingual broadcasting and the like, and devices capable of receiving audio multiplex signals have been put into practical use. In such equipment, voice multiplex signal reception control is important.

Hereinafter, an example of a conventional audio multiplex signal control circuit will be described with reference to the drawings. 2 and 3 show an example of a conventional audio multiplex signal control circuit.

In the figure, 1 is an antenna, 2 is a detector, 3 is a switching circuit, 4 is an amplifier, and 5 is a speaker.

First, the audio signal input from the antenna 1 is detected by the detector 2
After being detected by (1), it is separated into a main voice signal and a sub voice signal and input to the switching circuit 3. In the switching circuit 3,
The control signals A and B determine switching of signals output from the right output terminal and the left output terminal. The signal passed through the switching circuit 3 is input to the amplifier 4 and further reproduced by the left and right speakers 5.

Next, the switching operation of the switching circuit 3 will be described in detail.
First, when the mode control signal A is at a low level, the switching circuit 3
The switches 6 and 7 are closed to enter a mode in which the main voice and the sub voice are output respectively (main / sub voice mode). At this time, if the main / sub switching control signal B is at a low level, the switches 8 and 10 are closed and the right The main voice is output from the output terminal, and the sub voice is output from the left output terminal. On the other hand, if the main / sub control signal B is at a high level, the switches 9 and 11 are closed and the sub output is output from the right output terminal and the main output is output from the left output terminal.

Next, when the mode control signal A is at a high level, the switch 6 or the switch 7 of the switching circuit 3 is closed to output only one of the main voice and the sub voice (main voice mode or sub voice mode). Become. At this time, the main / sub switching control signal B
Is at a low level, the switches 6, 8 and 9 are closed, main sound is output to both the right output terminal and the left output terminal, and when the main / sub switching control signal B is at a high level, the switch 7,
The switches 10 and 11 are closed, and the sub audio is output to both the right output terminal and the left output terminal.

Problem to be Solved by the Invention However, in the conventional configuration as described above, the switching circuit 3
Is switched to the main / sub audio mode, the output is also switched by the main / sub switching control signal, which is originally for switching the main audio mode to the sub audio mode, and depending on the level of the control signal B, There is a problem that a strange phenomenon occurs in which signals output from both output terminals are exchanged.

In view of the above problems, the present invention switches the signals output from the right output terminal and the left output terminal without being influenced by the main / sub switching control signal when the switching circuit is switching the main / sub audio mode. The present invention provides a sound multiplex signal control circuit which does not exist.

In order to achieve this object, the audio multiplex signal control circuit of the present invention forcibly sets the level of the input terminal of the main / sub control signal when the mote switching control signal is in the main / sub audio mode. And a circuit for fixing the first level, for example, a diode provided between both terminals.

Operation With this configuration, the main / sub switching control signal is forcibly fixed by the newly added fixed circuit in the main / sub audio mode.
For example, it is possible to always output the main sound from the right output terminal and output the sub sound from the left output terminal, and to prevent the sound from being switched by the main and sub control signals. Become.

Example An audio output control circuit according to an example of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a voice multiple signal control circuit according to an embodiment of the present invention. In the figure, the same parts as those in FIGS. 2 and 3 are designated by the same reference numerals and the description thereof will be omitted. Reference numeral 12 denotes a diode as a level fixing circuit, which is inserted between the input terminals of the control signals A and B with the input end side of the control signal A as a cathode.

The operation of the audio multiplex signal control circuit configured as described above will be described. First, when the mode control signal A is at a low level, the switching circuit 3 enters the main / sub audio mode by closing the switches 6 and 7. At this time, the input terminal of the main / sub audio control signal B is forcibly fixed to the low level by the diode 12, and the switch
When 8 and 10 are closed, the main sound is always output from the right output terminal and the sub sound is output from the left output terminal.

Next, when the mode control signal A is at a high level, the switching circuit enters the main audio or sub audio mode by closing the switch 6 or the switch 7. At this time, if the main / sub switching control signal B is at a low level, the switches 6, 8 and 9 are closed and main audio is output to both the right output terminal and the left output terminal, and the main / sub switching control signal B is at a high level. If so, the switches 7, 10, and 11 are closed, and the sub audio is output to both the right output terminal and the left output terminal.

As described above, according to the present embodiment, by adding the diode 12 between the input terminal of the mode control signal A and the input terminal of the main / sub switching control signal B, the switching circuit 3 operates in the main / sub audio mode. Sometimes it can be fixed so that the main audio is always output from the right output terminal and the sub audio is output from the left output terminal.

As the fixed circuit for the main / sub switching control signal, a transistor or the like may be used instead of the diode.

As described above, according to the present invention, by adding the fixed circuit for the main / sub switching control signal, when the switching circuit is in the main / sub audio mode, the main / sub switching control signal affects the right output terminal. It is possible to prevent the sound from the left output terminal from being exchanged, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a voice multiplex signal control circuit according to an embodiment of the present invention, and FIGS. 2 and 3 are circuit diagrams of conventional voice multiplex signal control circuits. 3 ... Processing unit, 6,7,8,9,10,11 ... Switch, 12 ... Diode.

Claims (1)

[Claims] 1. A main audio mode in which both main audio signals are output from the left and right output terminals when the first control signal is at the first level and the second control signal is at the first level, and the first control is performed. When the signal is at the first level and the second control signal is at the second level, the sub audio mode in which both the left and right output terminals output the sub audio signal is set, and when the first control signal is at the second level, A processing circuit for switching between outputting the main audio or the sub audio from the left output terminal and outputting the sub audio or the main audio from the right output terminal according to whether the control signal of 2 is the first level or the second level And the first control signal is the second
The audio multiplex signal control circuit including a level fixing circuit for forcibly fixing the level of the input terminal of the second control signal to the second level when the level is 1.