KR950014472B1 - The color signal correction circuit in tv set - Google Patents

Abstract

The circuit is for compensating color signal which recording status on a video cassette is bad. The circuit comprises a video signal processor(10) for processing video signal reproduced in a VCR, a burst signal detector(20) for detecting a burst signal from a color signal and for generating control signal to control color signal compensation, a compensation signal processor(30) for storing and reproducing R,G,B signals transmitted from a video signal processor(10), and a switching unit(50) for outputting compensated or non-compensated color signal according to control signal transmitted from the burst signal detector(20).

Description

TV color signal correction circuit

1 is a flowchart of color correction performed by the color correction circuit of the present invention.

2 is a color signal correction circuit of the present invention TV.

3 is a phase angle and chroma vector diagram.

4A is a phase difference detection circuit diagram.

4 (b) and (c) are principle diagrams of phase detection.

5 is a block diagram of a TV color signal processing circuit according to the prior art.

* Explanation of symbols for main parts of the drawings

10: video signal processor 20: burst signal detector

30: correction signal processor 10-1: tuner

10-2: Video intermediate frequency detector 10-3: Sound IF & detector

10-4: video amplification unit 10-5: filter unit

10-6 to 10-8: demodulator 20-1: burst gate

20-2: burst gate pulse generator 20-3: phase detector

20-4: color level detector 20-5 frequency / voltage converter

30-1: Multiplexer 30-2: A / D Converter

30-3: microcomputer 30-4: pulse generator

30-5: Memory 30-6: D / A Converter

40: color killer

The present invention relates to color correction in TVs. In particular, when the color signal is poor according to the recording state of the tape during the playback of a V-Cal, the color of the TV is not normally displayed. The present invention relates to a TV color signal correction circuit for compensating a color signal to implement a clear color signal.

Commonly used meditation input devices include a drum scanner for color images, a three-color filter and a black-and-white TV camera. The former allows a higher resolution of the input image than the latter. The three primary color image processing system may use a monochrome image processing system by image processing using an RG B filter in front of the monochrome camera.

The video signal inputted by these conventional input devices is processed by the schematic circuit as shown in FIG. 5 so that the input video signal is separated into a luminance signal and a color signal, and then the color signal is a color demodulator. The signal is separated into an RY, GY, and BY signal by (2), and is stored in the flash memory 5 for each frame according to the frame switching signal and then converted and amplified into an analog signal.

The color signal is output through a selective path from the multiplexer 3 and mixed with the luminance signal of the image amplifier 1 and the adder 4.

However, this method digitalizes the color TV broadcast image input in the three-frame period to 256 * 256 * 6 bits with respect to the RG B image, so that the RG B image is displaced on the fast-moving screen, and 3 frames are input when the color image is input. There is a problem that only the period should be stopped.

Accordingly, an object of the present invention is to detect a color signal from a composite video signal, extract a burst component from the signal, and compare the level and phase with a reference value in order to solve the defects of the conventional video signal processing circuit. The present invention provides a color signal correction circuit that outputs a memory RG B signal when color signals are defective so that color signal correction is performed.

First, the present invention applies a digitalization memory in the conventional TV image processing circuit to detect the phase level of the color burst when the V video output signal or the TV broadcast signal is not a normal signal state due to noise or signal distortion to detect the reference signal When a difference occurs over a certain level, the delayed digital memory color signal is output so that the RGB signal, which has been digitally memoryd instead of the bad signal, is mixed with the luminance signal.

The circuit of the present invention for performing such an operation has a configuration as shown in FIG. 2 and will be described in detail as follows.

First, the video signal processor 10 is a video intermediate frequency detector 10-2 for performing intermediate frequency conversion and detection by local oscillation of a signal tuned by the TV tuner 10-1, and a broadcast signal or VRC. And a switch unit SW1 for selecting a specific signal from the camera output signal, a sound IF & detector unit 10-3 for audio output, and a filter unit 10-5 for extracting a color band from the composite video signal. And demodulators 10-6 to 10-8 for separately demodulating color signals of RY, GY and BY, a video amplifier 10-4 for amplifying a video signal, and RG B image signals. And an amplification unit 10-9 for amplifying a level or more, and CRT1 for receiving and displaying an image signal from the amplification unit 10-9.

The amplification unit 10-9 is controlled by the color killer 40 that causes only the black and white luminance signal to be displayed to the CRT1 by the compensation signal from the outside when the video signal is abnormal.

On the other hand, the burst signal detection unit 20 is a color burst gate 20-1 and burst gate pulse generator 201 for separating horizontal synchronization from the video signal for extracting the burst portion for each horizontal synchronization signal, and the color burst gate ( 20-1) and a phase detector 20-3 which performs phase detection based on the burst signal separated by the burst gate pulse generator 20-2, and a color for detecting the level of the pure color signal in the color burst portion. Receives the output signals of the level detector 20-4, the phase detector 20-3 and the color level detector 20-4, compares them with a reference voltage, and outputs a DC voltage at a point different from the reference level. Comparator COMP1 outputting a control voltage to a switching unit SW2 for selecting a signal and a corrected digital signal, and a signal corresponding to a phase shift of the burst signal is input to generate a reference signal according to the phase error. The key consists of a frequency / voltage converter 20-5.

On the other hand, the correction signal processing unit 30 is a multiplexer (30-1) for outputting each demodulated color R / G / B signal through each transmission path, and the digital signal to the output analog signal of the multiplexer (30-1) An A / D converter 30-2 for converting to a memory, a memory 30-5 for receiving the output of the A / D converter 30-2, and storing it at an address designated for each RGB region; A microcomputer 30-3 which sets a reference level and a phase for / G / B digital data separation and controls the memory 30-5 to store and output a delayed RGB signal, and a clock division signal and reference required for digitalization. And a pulse generator 30-4 for generating a clock, and a D / A converter 30-6 for converting an analog signal into a corrected color RG B signal.

The switching unit 50 includes an AND gate AD1 that receives an enable signal for color correction processing from the outside and an output control signal of the burst signal detection unit 20 for color correction control, and the AND gate AD1. And a color correction switch (SW2) for selecting the output of the image signal processing unit 10 or the output of the correction signal processing unit 30 and outputting to the CRT1 depending on whether or not color correction is performed. The color killer 40 is configured to control the CRT1 to control the color / black display.

Referring to the operation and the effect of the reference configuration of the present invention as described above in detail.

In the case of the general meditation receiving circuit, the broadcast signal received from the antenna ANT1 is converted into a composite video signal by the TV IN tuner stage 10-1, and thus, due to a poor reception state or interference of an external signal in the process of converting it into a composite video signal. In general, the video processing circuit used in the video processing circuit is attenuated or distorted. Therefore, when the video signal is poor due to poor recording conditions or errors in the playback system, the black and white luminance signal is instantaneously. The color killer 40 which makes this display is employ | adopted.

However, there is a need for correcting and outputting color signals, such as in the case of an educational tape that requires a certain level of color correction when a video tape is poorly recorded, or a color signal reception in an astigmatism area of a TV. In the present invention, as shown in the schematic color correction process of FIG. 1, the color correction switch SW2 is connected to a color correction switch SW2 for outputting to the CRT1 when the broadcast signal or the video reproduction signal is weakened. RG with 1H delay connected to (B) The B signal is output and the burst signal is extracted from the color signal in accordance with every horizontal synchronization for correction. The phase and level are detected and color correction is performed according to whether the value is out of the allowable range of the reference value.

First, the switch SW1 is used to select a broadcast signal or a V-CAL and a camera output signal. When a specific composite video signal is selected by switching of the switch SW1, the audio / audio signal is selected from the sound IF & detector unit. Extracted and detected by l0-3, amplified to a predetermined level by the amplifier A1, and then driven by the speaker SP1, and the RG B color signal is detected by the filter unit 10-5 to detect the demodulator ( 10-6 to 10-8) to selectively demodulate and output to CRT1.

The color signal detected by the filter unit 10-5 from the composite video signal and delayed by 1H is input to the demodulations 10-6 to 10-8 as described above and the burst gate 10-1 for color correction. ), Only the burst signal portion is extracted by the burst gate pulse, which is generated every 1H by horizontal synchronization.

On the other hand, phase error detection in the color signal, which is the core of the present invention, is based on the fact that the color signals combined by R. G. B have respective phases and levels as in the color phase analysis diagram of FIG.

If the composite ratio of the luminance signal and the color signal sensed by the general receiver exceeds the 10% frequency response level difference in one band, color distortion is remarkable. Therefore, this difference needs to be detected.

Accordingly, the phase detector 20-3 detects the phase θ value corresponding to the analog value and outputs a detection signal when the burst reference phase exceeds the error detection range corresponding to the frequency response l0%, and the color level detector 20-. 4), when the pure color signal is small, the killer 40 operates so that only the monochrome luminance signal is output from the CRT1, and the operation of the color killer 40 is stopped while performing the color correction process.

As an example of the circuit for detecting the phase error of the burst signal, the circuit of FIG. 4 (a) is presented, which constitutes a differential amplifier circuit with transistors Q3 and Q6 and another collector at its collector output stage. Differential amplifiers are configured by transistors Q1 and Q2 (Q4 and Q5), and two signals INPUT1 and INPUT2 for phase comparison are applied to the bases of the transistors Q1 to Q6.

This circuit detects the phase difference between the two signals, as shown in Figs. 4B and 4C, if the phases of the two input signals INPUT1 and INPUT2 are in phase or 90 deg. When the transistors Q3 and Q6 are alternately turned on and off according to (INPUT1 and INPUT2), and outputs accordingly, this AC signal is converted into a DC signal corresponding to the previous quarter (not shown). Is set to a predetermined value, the reference value for the frequency response level difference between the luminance signal and the color signal in one band is set to a value within the range of the set value and applied to the comparator COMP1 so that the burst reference phase responds to the frequency response. It will detect if it falls within the 10% range.

When a detection signal by one end of phase and level detection is output from the comparator COMP1, this signal is applied to the microcomputer 30-3 to perform the digital color memory.

That is, the color signal delayed by the filter unit 10-5 is converted through the A / D conversion unit 30-2 into a state of an RGB demodulation signal through the multiplexer 30-1 to each address. Is stored in the memory (30-5).

Simultaneously with the detection of the color phase and level errors, the 1H delayed digital color correction values are output as color signals through the digital / analog converter 30-6 and output through the RG B matrix to CRT1 in place of the error color signals. Display.

When the color signal becomes unstable through the above process, when the color correction switch SW2 is turned on, the image signal is replaced with the digitally corrected color, and when the correction is turned off, the original color state is displayed.

As described in detail above, the present invention enables an effective video signal by correcting and outputting color by correcting and outputting color when the recording state of a video tape is poor, and correcting color signal processing in other TV single viewing areas. As a result, viewing is possible.

Claims (5)

A video signal processor (10) for receiving a reproduction signal from a TV signal or a V-CAL and outputting a video signal and an audio signal separately, separating a color signal from a composite video signal, and demodulating each RG B signal to display the video signal; Burst signal detection unit 20 for receiving a color signal from the image signal processing unit 10 detects a burst signal, compares its phase and level with a reference value, and outputs a control signal for supporting color correction according to the comparison result. And a correction signal processor 30 which receives the RGB demodulated signal from the image signal detector 10 and stores the RGB demodulated signal in the memory and outputs the memorized image signal when the color signal is corrected, and the burst signal detector 20 Depending on the control, the color correction signal or the non-correction color signal is output selectively, and the color / monochrome display is removed. The color signal correction circuit of the TV, characterized in that consisting of a switching unit 50. The video signal processor (10) of claim 1, wherein the video signal processor (10) is a video intermediate frequency detector (10-2) for performing intermediate frequency detection on the signal selected by the TV tuner (l0-1) by local oscillation, and a broadcast signal and a V signal. The switch unit SW1 for selectively connecting the seed and camera output signals, the sound IF & detector unit 10-3 for detecting and detecting the audio signal and outputting the detected audio signal, and the sound IF & detector unit 10-3. An amplifying unit A1 for driving the speaker SP1 by amplifying the output signal to a predetermined level, a filter unit 10-5 for delaying a predetermined time for extracting a color band signal from the composite video signal, RY, GY, Demodulators (10-6 to 10-8) for separating and demodulating the color signal of BY, a video amplifier (10-4) for amplifying the composite video signal to a predetermined level, and amplifying the received RGB signal The knife of the TV, characterized in that consisting of amplification unit (10-9) for driving the tee (CRT1) Signal correction circuitry. The burst gate detector of claim 1, wherein the burst signal detector 20 extracts a burst signal component from a color signal every horizontal synchronization, separates the horizontal synchronization from the video signal, and transfers the burst signal to the burst gate pulse generator 20-2. 20-1, a phase detector 20-3 which detects a phase error on the basis of the burst signal safely separated by the burst gate 20-1 and the burst gate pulse generator 20-2, and a burst signal. Receives a level detector 20-4 that detects the level of the pure color component, and output signals of the phase detector 20-3 and the color level detector 20-4, and compares them with the reference level. A comparator C0MP1 outputting a color correction control signal when it is out of the way, and a frequency / voltage change providing a reference signal for the comparator COMP1 by converting a DC voltage corresponding to a signal according to a phase error. The television, characterized in that composed of group 20-5 color signal correction circuit. The multiplexer (30-1) of claim 1, wherein the correction signal processor (30) receives and outputs signals of color RGB of the demodulators (10-6 to 10-8) through respective transmission paths. And an A / D converter 30-2 for converting the output signal of the multiplexer 30-1 into a digital signal, and a memory 30 for storing digital data corresponding to each color element of RG B for each RGB region at a specified address. -5), and sets a reference level and phase for RGB digital data separation and stores the output data of the A / D converter 30-2 in a designated memory 30-5 address and outputs it when color corrected. The microcomputer 30-3 for controlling, the pulse generator 30-4 for generating the clock division signal and the reference clock required for digitalization, and the corrected color RGB signal are converted into analog signals to convert the color correction switch SW2. The D / A conversion unit 30-6 that transmits to CRT1 through Correction circuit for color television signals according to Gong. 2. The switch of claim 1, wherein the switching unit (50) includes: an AND gate (AD1) receiving an enable signal for color correction processing and an output control signal of the burst signal detection unit (20) for color correction control; The color correction switch SW2 driven by the AND gate AD1 and selectively outputting the output of the image signal processor 10 or the output of the correction signal processor 30 to the CRT1 depending on whether or not color correction is performed. And a color killer (40) for controlling the color / black display by controlling the CRT1 during color correction.