KR0160235B1 - Doming prevention apparatus of a tv - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to image processing of a TV receiver. In the related art, the color purity of an RGB image signal displayed on a CPT is changed, that is, the contrast and luminance control generated by the contrast and luminance control signal generators to prevent dominant phenomenon. The circuit that outputs a constant control signal from the anti-doming means to control the signal, and when the screen state of the CPT is high brightness, the contrast of the entire screen must be lowered, so the picture quality of the CPT screen is reduced, and the circuit configuration is complicated. In accordance with the use of a special CRT (Inva mask) there was a problem that the rise in manufacturing cost and productivity is lowered.

Therefore, the present invention is to solve the above problems, when the screen of the CPT is dark due to the dominant phenomenon of the CPT, that is, the color purity is changed to generate a high-brightness screen, partial gamma correction to prevent the doming phenomenon By constructing the circuit, the image quality of the CPT screen is not reduced by adjusting the contrast, and the circuit configuration is simplified, and the TV receiver can reduce the manufacturing cost and improve the productivity by eliminating the use of a special CRT tube. Anti-doming device.

Description

Doming prevention device of TV receiver

1 is a block diagram showing the structure of a dominant device of a conventional TV receiver.

Figure 2 is a block circuit diagram showing the structure of the anti-doming device of the present invention TV receiver.

Figure 3 (a) is a front view of the dominant phenomenon appears in the TV receiver of the present invention.

(b) is a horizontal pulse waveform diagram generated in a certain section of the CPT screen in the present invention.

(c) is a diagram of the undoming pulse waveform generated in the pulse generator of the present invention.

* Explanation of symbols for main parts of the drawings

21: ABL detector 22: reference voltage generator

23 comparison unit 24 doming control output unit

25 pulse generator 26 image amplifier

27 gamma correction unit 28 CPT matrix unit

29: AND gate Q1: transistor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to image processing of a TV receiver, and more particularly, to an anti-domming device of a TV receiver which attempts to prevent dominant phenomenon occurring in a CRT during reproduction of a TV image.

Here, the doming phenomenon refers to a phenomenon in which the color purity of the CPT due to the video signal is distorted.

The configuration and operation of the anti-doming device of a conventional TV receiver will be described with reference to FIG. 1 as follows.

First, amplifying means for amplifying the input video signal (-Y), a control signal generating means for generating a predetermined control signal to control the contrast and brightness of the video signal (-Y) amplified by the amplifying means; And anti-domming means for controlling a constant control signal generated by the control signal generating means to prevent the doming phenomenon of the image signal (-Y).

The amplifying means includes a brightness control unit 1 for controlling the contrast of the input image signal -Y, and a brightness control unit for controlling the brightness of the image signal -Y whose contrast is controlled by the contrast control unit 1. A control unit 2 and an RGB matrix unit 3 which converts and outputs the image signal (-Y) whose brightness and brightness are controlled to an RGB image signal for screen output to the CPT. The control signal generating means controls the contrast and brightness of the contrast and brightness controllers 1 and 2 configured in the amplifying means so as to control the contrast and brightness of the image signal (-Y) according to the input ABL voltage. Contrast and brightness control signal generators 4 and 5 for generating a control signal.

In addition, the anti-doming means includes a low pass filter unit 6 for filtering only the low pass components of the image signal (-Y) amplified and output by controlling the contrast and luminance in the amplifying means, and the horizontal (H) and vertical (V) inputs. Horizontal and vertical parabola generators 7 and 8 for generating horizontal and vertical parabola waveforms by varying pulses to constant levels of horizontal and vertical periods, and generated in the horizontal and vertical parabola generators 7 and 8. A mixing unit 9 for mixing horizontal and vertical parabola waveforms, and a horizontal and vertical parabola waveform mixed and output from the image signal (-Y) of the low pass component filtered by the low pass filter unit 6 and the mixing unit 9. By comparing the above, the area amount of the first comparator 10 for detecting the high luminance component of the low frequency component video signal (-Y) and the first comparator 10 detected by the first comparator 10 High brightness area detection part 11 to detect, and reference electric field input Contrast and luminance generated by the contrast and luminance control signal generators 4 and 5 according to Vref and the area of the high luminance component of the image signal (-Y) outputted by the amount of area detected by the high luminance area detector 11. The control unit 13 for controlling the control signal.

Referring to the operation of the anti-doming device of the conventional TV receiver configured as described above are as follows.

First, when the image signal (-Y) input from the TV receiver is displayed on the CPT,

The input image signal (-Y) is input to the RGB matrix unit 3 while the contrast and the brightness are controlled by the contrast and brightness controllers 1 and 2.

In addition, the RGB matrix unit 3 converts and outputs the input image signal (-Y) into an RGB image signal so that the CPT can be outputted to the CPT. Let's go.

In this case, when a doming phenomenon due to color purity is distorted in the RGB image signal displayed by the input image signal (-Y),

When the image signal (-Y) whose contrast and brightness are controlled by the contrast and brightness control unit (1) (2) is outputted to the low pass filter unit (6) configured in the anti-doming means, the low pass filter unit (6) Only the low pass component of the image signal (-Y) is filtered and then output to the first comparator 10.

On the other hand, the horizontal and vertical parabola generating unit (7) (8) converts the input horizontal (H) and vertical (V) pulses to a constant level of the horizontal and vertical scanning period to generate a horizontal and vertical parabola waveform to generate a mixing unit ( Output to 9),

In the mixing unit 9, the input horizontal and vertical parabolic waveforms are mixed and then output to the first comparator 10.

That is, the first comparison unit 10 compares the horizontal and vertical parabola waveforms which are mixed and output by the mixing unit 9 with the image signal (-Y) filtered only by the low pass component in the low pass filter unit 6. The high luminance component of the low-frequency component video signal (−Y) is detected and output to the high luminance area detector 11.

In this case, the high luminance area detection 11 detects an area amount of the detected high luminance component and outputs the detected area amount to the second comparison unit 12, and the second comparison unit 12 detects an area amount of the image signal (−). The high luminance component of Y) is compared with the preset reference voltage Vref and output to the controller 13.

Therefore, the controller 13 controls the brightness and brightness control signal generators 4 and 5 configured in the control signal generator according to the area of the reference voltage Vref and the high luminance component compared by the second comparator 12. ), A constant control signal for controlling the contrast and luminance control signals is outputted.

That is, the contrast and brightness control signal generators 4 and 5 control the contrast and brightness control signals generated according to the input ABL voltage while being controlled by the constant control signal output from the controller 13. The controlled contrast and luminance control signals are outputted to (1) and (2).

Therefore, the video signal (-Y) input to the TV receiver is output to the CPT by preventing the dominant phenomenon due to the color purity being distorted while passing through the contrast and luminance control unit (1) (2).

However, the anti-doming apparatus of the conventional TV receiver is adapted to control the contrast and luminance control signals generated by the brightness control signal generators 4 and 5 in order to prevent the color purity of the RGB image signals displayed on the CPT, that is, the dominance. By configuring a circuit that outputs a constant control signal from the anti-doming means to control, when the screen state of the CPT is high brightness, the contrast of the entire screen must be lowered, so that the image quality of the CPT screen is reduced, By using a special CRT (Inva mask) there was a problem that the rise in manufacturing cost and productivity is reduced.

Therefore, in order to solve the problem, the present invention is to prevent the doming phenomenon by performing partial gamma correction when the screen of the CPT becomes dark due to the dominant phenomenon of the CPT, that is, the color purity is changed and a high luminance screen is generated. By constructing the circuit, the image quality of the CPT screen is not reduced by adjusting the contrast, and the circuit is simplified, so that the use of a special CRT is unnecessary, thereby reducing manufacturing costs and improving productivity.

The configuration and operation of the anti-doming device of the present invention TV receiver for achieving the above object will be described with reference to FIG.

First, an ABL detector 21 for detecting and outputting a constant voltage converted according to the brightness of the CPT screen, and a reference voltage generator for generating an appropriate constant reference voltage of the reference brightness of the CPT screen ( 22) a comparison unit 23 for comparing the amount of change of the constant voltage detected and output by the ABL detector 21 with the constant reference voltage generated by the reference voltage generator 22 to output a comparison voltage of a predetermined level; And a dominant control output unit 24 for controlling an output operation of the dominant removal pulse signal according to a predetermined level of the comparison voltage output from the comparator 23, and an image for amplifying and outputting the input image signal (-Y). A gamma correction unit 27 for gamma-correcting the image signal (-Y) amplified and output from the image amplifier 126 according to a control operation of the amplifier 26 and the dominant control output unit 24, and the gamma The gamma corrected video signal (-Y) by the correction unit 27 is outputted on the CPT screen. The CPT matrix unit 28 converts and outputs an RGB video signal for output.

In addition, the dominant control output unit 24 outputs a dominant removal pulse signal for removing dominant phenomena on the CPT screen, and a predetermined level of comparison voltage output from the comparator 23. The gamma correction unit 27 is provided by the AND gate 29 which operates to output the dominant removal pulse signal generated by the pulse generator 25, and the dominant removal pulse signal output by the operation of the AND gate 29. It is composed of a transistor (Q1) for the on / off switching operation to control the operation of.

Reference numeral R1-R3 denotes a resistor, C1 denotes a capacitor, and ZD1 and ZD2 denote a Zener diode.

Referring to the operation of the anti-doming device of the present invention TV receiver configured as described above is as follows.

First, when the image signal (-Y) input is amplified by the image amplifier 26 and output to the CPT matrix unit 28,

The CPT matrix unit 28 converts and outputs an RGB image signal roll so that the image amplified and input image signal (-Y) can be output to the CPT screen. In the CPT, the RGB image signal is displayed on the screen.

At this time, in the RGB image signal displayed on the screen of the CPT by the input image signal (-Y), as shown in (a) and (b) of FIG. When doming occurs due to

The ABL detector 21 outputs a constant voltage, which changes according to the brightness of the CPT screen, to the positive terminal of the comparator 23 through the resistor R1 and the capacitor C1, The negative terminal is connected with a constant power source B + to input a constant reference voltage suitable for the reference brightness of the CPT screen output from the reference voltage generator 22 formed of the resistor R2 and the zener diode ZD1.

Accordingly, the comparison unit 23 compares the amount of change of the constant voltage input to the positive (+) (-) terminal with the constant reference voltage, and compares the constant voltage of the predetermined level with the AND gate 29 configured in the dominant control output unit 24. Will be printed).

That is, when the constant voltage detected by the ABL detector 21 is outputted high, the comparator 23 outputs a high level comparison voltage based on the constant reference voltage and the constant voltage detected by the high voltage, and the AND gate ( 29).

At this time, in order to remove the dominant phenomenon of the CPT screen, as shown in (c) of FIG. 3, the pulse generator 25 configured in the dominant control output unit 24 to generate a dominant removal pulse signal is used. According to the operation of (29), the dominant removal pulse signal is applied to the base of the transistor Q1.

In the transistor Q1, the gamma correction unit 27 including the resistor R3 and the zener diode ZD2 is operated while the ON operation is performed during the high period of the dominant removal pulse signal applied to the base. It will work.

Accordingly, the image signal (-Y) amplified by the image amplification unit 26 and output to the CPT matrix unit 28 is gamma-corrected according to the operation of the gamma correction unit 27, thereby performing the correction of the image signal (-Y). The high brightness portion is reduced to eliminate the doming phenomenon generated on the CPT screen as shown in FIG.

On the other hand, when the constant voltage detected by the ABL detector 21 is output low, the comparison unit uses a constant reference voltage and a low voltage detected by the constant voltage to determine a low level comparison voltage in the dominant control output unit 24. By outputting to (29), the AND gate 29 stops the operation while the undoming pulse signal generated by the pulse generator 25 configured in the dominant control output unit 24 is the base of the transistor Q1. Not authorized to

That is, the transistor Q1 is turned off without applying the undo removal pulse signal, and the operation of the gamma corrector 27 is also stopped according to the off operation of the transistor Q1.

Accordingly, the image amplifier 26 operates as an ACL (Auto Control Light) when amplifying and outputting the input image signal (-Y), thereby preventing the dominant phenomenon caused by the image signal (-Y). It is to suppress.

As described above, in the present invention, when the screen of the CPT becomes dark due to the dominant phenomenon of the CPT, that is, the color purity is changed, and a high brightness screen is generated, the circuit is configured to prevent the dominant phenomenon by performing partial gamma correction. In addition, the image quality of the CPT screen is not reduced by adjusting the contrast, and the circuit configuration is simplified, so that the use of a special CRT is unnecessary, thereby reducing manufacturing costs and improving productivity.

Claims (3)

An ABL detector 21 for detecting and outputting a constant voltage that changes according to the brightness of the CPT screen, and a reference voltage generator 22 for generating an appropriate constant reference voltage of the reference brightness of the CPT screen. And a comparison unit 23 for comparing the amount of change of the constant voltage detected and output by the ABL detector 21 with the constant reference voltage generated by the reference voltage generator 22 to output a comparison voltage of a predetermined level, and the comparison. A dominant control output unit 24 for controlling the output operation of the dominant removal pulse signal according to the comparison voltage of a predetermined level output from the unit 23, and an image amplifying unit which outputs the input image signal (-Y) with a heavy weight ( 26, a gamma correction unit 27 for gamma-correcting an image signal (-Y) amplified and output from the image amplifier 26 according to a control operation of the dominant control output unit 24, and the gamma correction unit ( 27) to output the gamma-corrected video signal (-Y) to the CPT screen. Know ratio (RGB) video signal conversion output roll television (TV) Dominguez prevent the receiver device consisting of CPT-matrix section 28 in order to. 2. The dominant control output unit 24 according to claim 1, wherein the dominant control output unit 24 compares the pulse generator 25 for outputting the undoming pulse signal for removing the dominant phenomenon of the CPT screen from the constant level output from the comparator 23. Gamma correction is performed by an AND gate 29 that operates to output the dominant removal pulse signal generated by the pulse generator 25 according to the voltage, and an dominant removal pulse signal that is output according to the operation of the AND gate 29. An anti-doming device for a television (TV) receiver, comprising: a transistor (Q1) for on / off switching operation to control the operation of (27). The gamma correction unit 27 performs gamma correction when the high luminance portion of the image signal (-Y) matches the dominant generation region when the CPT screen is dark due to the resistor R3 and the zener diode ZD2. Anti-doming device of a TV (TV) receiver, characterized in that.