JPH066702A - Television receiver - Google Patents

Abstract

PURPOSE:To improve sensitivity for discriminating silence by using both of a detection signal from a synchronizing signal detecting circuit and a discrimination signal from a color system discriminating circuit for a means for discriminating a silence signal in a video signal. CONSTITUTION:A synchronizing signal detected by a synchronizing signal detecting circuit 12 is supplied to a horizontal synchronizing signal detecting circuit 11 to detect a synchronizing signal. A color system discriminating circuit 14 discriminates the color system of a chrominance signal, and at the time of discriminating a monochromatic signal including no chrominance signal, the supply of a discriminating signal to a discriminating signal generating circuit 15 is stopped. Thereby when a silence signal or a noise signal is outputted, no chrominance signal is included and a monochromatic state is discriminated, so that no discriminating signal is supplied to the circuit 15. Thus a silence discriminating signal is outputted only when a detection signal from the circuit 11 and the discriminating signal from the circuit 14 are not supplied, improving sensitivity in the discrimination of silence in the video signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal discriminating circuit of a television receiver.

[0002]

2. Description of the Related Art In recent years, a television receiver is often added with functions such as erasing voices and displaying a back-back screen when noise occurs. A sync signal is often used for the non-signal discrimination of the video signal having the above function.

A video signal discriminating circuit of a conventional television receiver will be described below. FIG. 2 is a block diagram showing a circuit configuration of a video signal discrimination circuit of a conventional television receiver. In FIG. 2, 21 is a sync signal detection circuit for detecting a sync signal, 22 is a sync signal detection circuit, and 23 is a deflection circuit.

The operation of the video signal discriminating circuit of the conventional television receiver configured as described above will be described below. The video signal is supplied to the sync signal detection circuit 22, and the detected sync signal is output to the deflection circuit 23. Also,
The sync signal detected by the sync signal detection circuit 22 is supplied to the sync signal detection circuit 21 to detect the sync signal. The no-signal of the video signal is discriminated by the detection signal of the sync signal detection circuit 21.

[0005]

However, in the above-mentioned conventional circuit configuration, since the non-signal discrimination of the video signal is performed only by detecting the sync signal, in the special reproduction of the VTR, the video signal is not detected by the malfunction of the sync signal detection. There is a problem that erroneous discrimination occurs in signal discrimination.

It is an object of the present invention to provide a television receiver having an improved sensitivity of non-signal discrimination of video signals.

[0007]

In order to achieve this object, the television receiver of the present invention uses a black-and-white signal discrimination of a color system discrimination circuit to improve discrimination sensitivity in addition to the conventional sync signal detection circuit. Plan.

[0008]

With this configuration, the discrimination sensitivity can be improved by supplementing the conventional sync signal detection circuit with the monochrome signal discrimination of the color system discrimination circuit.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 11 is a sync signal detection circuit,
Reference numeral 12 is a synchronization signal detection circuit, 13 is a deflection circuit, 14 is a color system discrimination circuit, and 15 is a discrimination signal generation circuit.

Regarding the video signal discriminating circuit of the television receiver configured as described above, the video signal for explaining the operation thereof is supplied to the synchronizing signal detecting circuit 12 and the detected synchronizing signal is output to the deflecting circuit 13. It The sync signal detected by the sync signal detection circuit 22 is supplied to the sync signal detection circuit 21 to detect the sync signal. The color system discriminating circuit 14 discriminates the color system of the color signal and does not include the color signal, that is, stops the supply of the discriminating signal to the discriminating signal generating circuit 15 at the time of monochrome discrimination. Therefore, when there is no signal and no noise signal, the color signal is not included, and black-and-white determination is performed, and the determination signal is the determination signal generation circuit
Will not be supplied to. The discrimination signal generation circuit 15 is composed of respective switch circuits which are opened and closed by the detection signal from the synchronization signal detection circuit 11 and the discrimination signal of the color system discrimination circuit 14, and the detection signal from the synchronization signal detection circuit 11 and the color system discrimination When the discrimination signal of the circuit 14 is supplied, each switch circuit is closed. Therefore, the no-signal discrimination signal is output from the discrimination signal generation circuit 15 only when the detection signal from the synchronization signal detection circuit 11 and the discrimination signal from the color system discrimination circuit 14 are not supplied. As a result, the conventional sync signal detecting circuit 11 is supplemented by the color system discriminating circuit 14 and the discriminating sensitivity can be improved.

[0012]

As described above, the present invention can improve the discrimination sensitivity by using the discrimination signal of the color system discrimination circuit 14 in addition to the conventional synchronizing signal detection circuit.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a television receiver according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit configuration in a conventional television receiver.

[Explanation of symbols]

 11 sync signal detection circuit 12 sync signal detection circuit 13 deflection circuit 14 color system discrimination circuit 15 discrimination signal generation circuit

Claims (1)

[Claims] 1. A synchronization signal detection circuit and a color system discrimination circuit are provided, and both of the detection signal of the synchronization signal detection circuit and the discrimination signal of the color system discrimination circuit are used as means for discriminating no signal of the video signal. Featured television receiver.