JP2932089B2 - Video / audio elimination circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a video and audio erasing circuit for a television receiver or the like.

(Prior Art) In recent years, television receivers have become more and more multifunctional, and the need to eliminate noise when switching functions has been increasing.

Hereinafter, a conventional video / audio elimination circuit of a television receiver will be described with reference to the drawings. FIG. 2 shows a configuration of a video erasing circuit of a conventional television receiver. In FIG. 2, 21 is a surround circuit for adding a special sound effect, 22 is a microcomputer, 23 is a pulse generation circuit for generating an erasure control signal by a switch signal of the surround circuit, 24 is a diode for mixing, and 25 is an audio signal And 26, a switching transistor for erasing the video signal.

The operation of the conventional video / audio elimination circuit configured as described above will be described below.

When the power of the television receiver is turned ON / OFF and the channel is switched, an erasing control signal is output from the microcomputer 22 and the switching transistor 25 for erasing the audio signal passes through the diode 24 to the switching transistor 26 for erasing the video signal. Directly supplied, each performs an erase operation.

Here, in the case of surround switching, a switching signal is output from the microcomputer 22 to perform switching of the surround circuit, and the switching signal is also supplied to a pulse generating circuit 23 that generates an erasing control signal and is generated by the pulse generating circuit 23. The erase control signal is applied to the switching transistor 25.
The voice supplied to is deleted. At this time, diode 24
In this case, no erasing control signal is supplied to the switching transistor 26 that erases the video signal, and only the audio is erased without performing the erasing of the video when the surround is switched as a function related to the audio.

(Problems to be Solved by the Invention) However, the above-described conventional video / audio erasing circuit of a television receiver is configured by the same control signal from the microcomputer when erasing only audio as the number of functions increases. However, there is a problem that a pulse generating circuit is required as in the above-described conventional image erasing circuit.
Alternatively, when the pulse generation circuit is not used, there is a problem that the control signal from the microcomputer must be output separately for video and audio, and the output terminal of the microcomputer needs to be added.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a video and audio erasing circuit which does not require a pulse generation circuit and does not need to separately output a control signal of a microcomputer for video and audio. It is the purpose.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, a video / audio erasing circuit comprises a control signal generating means (microcomputer) for generating a control signal for controlling a television receiver, Conversion means for converting a control signal output from the signal generation means into a first erasure signal and a second erasure signal; outputting a video control signal for erasing a video signal by the first erasure signal; Conversion means for outputting an audio control signal for erasing an audio signal by an erasure signal, a switch transistor), and converting means according to three signals of L, H and high impedance (open) output from the control signal generation means. Output the first erase signal and the second erase signal together, output the first erase signal and the second erase signal together, and output only the second erase signal The state is controlled to be such that video and audio are each erased according to an erasing signal output from an erasing means corresponding to the type of control signal from a control signal generating means for controlling the television receiver. is there.

(Operation) Therefore, according to the present invention, with the above-described configuration,
When erasing only audio, increase the number of output terminals of the microcomputer without providing a conventional pulse generation circuit and without having to separately output control signals from the computer for video and audio separately. And a simple circuit.

(Embodiment) Hereinafter, a video and audio erasing circuit of a television receiver according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a circuit configuration of a video / audio elimination circuit according to an embodiment of the present invention. In FIG. 1, 11 is a surround circuit for adding a special sound effect, 12 is a microcomputer, 13 is a conversion circuit for converting a control signal from the microcomputer 12, 14 is a switching transistor for erasing a video signal, and 15 is audio. It is a switching transistor for erasing a signal.

The operation of the circuit connected as described above will be described below. In the above embodiment, when the normal erasing operation is not performed, the microcomputer 12 outputs an “H” control signal and supplies it to the conversion circuit 13.

Here, the conversion circuit 13 is composed of two transistors, an NPN transistor a and a PNP transistor b. The base is connected to the microcomputer 12 through resistors, and the transistor a has the emitter grounded and the collector erases the video signal. It is connected to a power supply via the base of a switching transistor 14 and a resistor. The transistor b has the emitter connected to the power supply and the collector connected to the resistor to ground the switching transistor 15 for erasing the audio signal via the resistor and the resistor.

In the conversion circuit 13 configured as described above, when “H” is input, the transistor a is turned on and the transistor b is turned on.
Is turned off, the bases of the switching transistor 14 for erasing the video signal and the switching transistor 15 for erasing the audio signal are both at "L", and both the video and audio are not erased.

When the power of the television receiver is turned on / off and the channel is switched, an “L” control signal is output from the microcomputer 12 and supplied to the conversion circuit 13. In the conversion circuit 13, the transistor a is turned off, the transistor b is turned on, and the base of the switching transistor 14 for erasing the video signal and the base of the switching transistor 15 for erasing the audio signal are both "H", and both the video and audio are erased. Becomes

Here, in the case of surround switching, a “high impedance” control signal is output from the microcomputer 12 and supplied to the conversion circuit 13. In the conversion circuit 13, both the transistor a and the transistor b are turned ON, the base of the switching transistor 14 for erasing the video signal is "L" and the video is not erased, and the base of the switching transistor 15 for erasing the audio signal is “H”
Is in a state in which only voice erasure is performed.

(Effects of the Invention) As is clear from the above embodiment, the present invention converts three signals of L, H, and high impedance (oven) output from the control signal generating means (microcomputer) by a conversion circuit, Erasing means), the video signal and the audio signal are erased by supplying the signals to the switching transistor). Control signals from the
In order to output the voices separately, the output terminal of the microcomputer is not added and the circuit is constituted by a simple circuit.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a video / audio elimination circuit of a television receiver according to an embodiment of the present invention, and FIG. 2 is a circuit configuration diagram of a video / audio elimination circuit of a conventional television receiver. 11,21 surround circuit, 12,22 microcomputer, 13 conversion circuit, 14,15,25,26 switching transistor, 23 pulse generation circuit, 24 diode.

Claims (1)

(57) [Claims] 1. A control signal generating means for generating a control signal for controlling a television receiver, and a conversion for converting a control signal output from the control signal generating means into a first erasing signal and a second erasing signal. Means for outputting a video control signal for erasing a video signal in accordance with the first erasing signal and outputting an audio control signal for erasing an audio signal in accordance with the second erasing signal; A state in which the converting means outputs both the first erasing signal and the second erasing signal in response to three signals of L, H and high impedance output from the signal generating means; 2 in a state in which both of the erasing signals are not output and a state in which only the second erasing signal is output, and the erasing means according to the type of the control signal from the control signal generating means for controlling the television receiver. A video and audio erasing circuit for erasing each of video and audio according to an erasing signal output from the video / audio erasing circuit.