JPH0289493A - Television signal processing circuit - Google Patents

Abstract

PURPOSE:To derive a prescribed test signal to a chrominance signal output terminal and to test the motion of a processing circuit in a condition without a TV signal by processing the signal of a selfoscillating circuit by means of a logical circuit. CONSTITUTION:When a color difference signal and a video signal are not applied from the outside, by respectively connecting switches 14 to 16 to an (X) side, a prescribed waveform output is obtained from a logical circuit 11 in a horizontally deflecting automatic frequency control system 18. Thus, respective R, G and B test signals can be derived from chrominance signal output terminals 1, 2 and 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the functional configuration of a Rarebi signal processing circuit used in a television receiver.

Conventional technology Conventionally, various signal processing circuits used in television receivers include:
It consists of a circuit whose original purpose is to process the received signal, and no output can be obtained unless an input is applied to the integrated circuit.

Problems to be Solved by the Invention In the case of unmanned power as described above, the output is not constant and becomes an unstable phenomenon. You may also want to check that no input has been added (but the image is displayed).

Means for Solving the Problems In order to solve these problems, a test signal generator capable of outputting the output as shown in FIG. 2 is built into the signal processing circuit for video, chroma, deflection, etc. The self-oscillating signal from the horizontal oscillation circuit of the deflection signal processing section is processed by a logic circuit and output to red, green, and blue color signal output terminals as a test signal output.

Effect This allows you to utilize existing circuits and signals for open signal processing! With no TV signal applied to the I-den circuit,
It can produce images with a certain pattern.

Example The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a functional block diagram showing an example of the present invention, and FIG. 2 is an output signal waveform diagram thereof.

In Fig. 1, 10 is a color signal output terminal 1, 2 and 3 which outputs red, green and blue color signals after predetermined processing and demodulation of the video signal and color difference signal applied from outside the television receiver. This is the video and color signal processing circuit that sends the signals to the 18 dotted lines indicate 12 voltage-controlled oscillators VCO1 that self-oscillate at a frequency 32 times the horizontal oscillation frequency fo.
11 frequency division and logic circuit, 13 that detects the phase error with the oscillation frequency based on the externally input synchronization signal
This is an automatic frequency control system for horizontal deflection, which is composed of a phase comparator, a circuit that smooths the malfunction voltage corresponding to the phase difference with a filter 9, and then returns it to the VCO 12.

In the present invention, normally, the television signal from IO is taken out to the output terminals 1.2 and 3 and applied to the video output circuit.
The horizontal deflection signal of the automatic frequency control system is taken out from terminal 4 and applied to the horizontal deflection drive circuit in the same way as the conventional example, but when no external television signal is applied, the test signal shown below is applied. The purpose is to take out the data from each of the output terminals. 14. Switches 15 and 16 are electronic switches for sending either the television signal from 10 during normal operation or the test signal from 11 during unmanned operation to the color signal output terminals at 1°2 and 3. When color difference signals and video signals are not applied externally,
Switches 14, 15 and 16 are each set to the X side, and 11
By configuring the logic circuit in such a way that the waveform output shown in FIG.
Green and blue test signals can be extracted.

Effects of the Invention According to the present invention, by processing the signal of the self-oscillation circuit with a logic circuit, a predetermined test signal can be drawn out to the color signal output terminal, so that the operation of the signal processing circuit can be performed in the absence of a television signal. Can be tested.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram of a circuit according to an embodiment of the present invention, and FIG. 2 is a test signal waveform diagram. 1.2.3... Color signal output terminal, 4...
・Horizontal deflection signal output terminal, 10... Signal processing circuit, 11... Frequency division/logic circuit, 12...
・Voltage controlled oscillator, 13...phase comparator. Name of agent: Patent attorney Shigetaka Awano One idiot Figure 1

Claims (1)

[Claims] This is a semiconductor integrated circuit that contains signal processing circuits for video, chroma, and deflection of television receivers, and uses the output of a self-oscillating horizontal oscillation circuit to generate red, green, and other signals without any external input. A TV signal processing circuit with a built-in test signal generator that can output a certain waveform from the blue color signal output terminal.