KR100296417B1 - correcting Apparatus of Image-Quality for Black Screen - Google Patents

Abstract

The present invention relates to an image quality correcting apparatus of a black screen configured to correct an image quality of a projector on a dark screen.

According to an aspect of the present invention, an apparatus for compensating image quality of a black screen includes a color decoder which separates a composite video signal into a luminance signal and a color difference signal, a color difference signal separated by the color decoder, and a luminance signal converted into an analog signal by a digital analog converter. An image processing unit for processing green and blue signals, an analog digital converter for converting the red, green, and blue analog signals into a digital signal, a scaling unit for scaling the digital signal to fit the size of a liquid crystal panel, and a digital signal A digital analog converter for converting a signal into an analog signal, a gamma control unit for adjusting brightness characteristics of the liquid crystal panel, a driver unit for supplying a driving signal to drive the liquid crystal panel, and sampling and holding the driving signal supplied from the driver unit. In the liquid crystal projector having a sampling / holder portion, the color deco The luminance signal separated by the negative unit is converted into a digital signal by the analog digital converter, and stores a field memory for one image, a controller for distributing the image stored in the field memory at predetermined time intervals, and by the controller. An input signal level detector for detecting a level of an input signal distributed at a predetermined time interval at predetermined time intervals, a gray level detector for detecting a level of black and white of the signal distributed by the input signal level detector at predetermined time intervals; A black screen gray level extending unit for extending the black gray level so as to correspond to the black and white contrast of the signal input from the gray level detecting unit, and detected by the input signal level detecting unit to correspond to the level of the luminance signal detected from the composite video signal; The brightness level of the signal is varied and supplied to the driver unit. And a brightness variable switch processing unit.

With such a configuration, the black screen image quality correcting apparatus according to the present invention improves the video quality by correcting the video quality on a dark screen.

Description

Correcting Apparatus of Image-Quality for Black Screen}

The present invention relates to a projector device, and more particularly, to an image quality correction device of a black screen configured to correct an image quality of a projector on a dark screen.

Recently, with the spread of liquid crystal projector devices, it is becoming a general trend in homes and offices. On the other hand, liquid crystal displays (hereinafter referred to as "LCDs") are difficult to implement contrast due to their characteristics, and contrast in a dark screen is a conventional cathode ray tube (hereinafter referred to as "CRT"). It is quite inferior to the characteristics of, which makes it difficult to implement images or moving images. Unlike the conventional CRT, to solve this difficulty, gamma correction is performed at the final output stage, but its characteristics are not perfect. Hereinafter, this will be described with reference to FIGS. 1 to 3.

Referring to FIG. 1, a conventional image quality compensation device includes a color decoder 2 for separating a complex video signal CVBS into a luminance signal Y and a color difference signal UV, a color difference signal UV, and a luminance signal Y. ), An image processing unit 4 for processing an RGB signal into an RGB signal, an ADC 6 for converting an analog RGB signal into a digital RGB signal, a scaling unit 8 for scaling an RGB signal to fit the size of a liquid crystal panel, and a digital DAC 10 for converting the signal to analog, gamma control unit 12 for adjusting the brightness characteristics of the liquid crystal panel, driver unit 14 for driving the liquid crystal panel, and sampling / holding for sampling / holding the liquid crystal panel drive signal. The holder part 16 is provided. The color decoder 2 separates the composite video signal CVBS into a luminance signal Y and a color difference signal UV. In this case, the luminance signal Y and the color difference signal UV are appropriately processed by the image processing unit 4 so that red (Red) and green (G) are referred to. And blue (hereinafter, referred to as 'B') signals. In addition, the RGB signal is converted into a digital signal when an image signal is selected through a switching process with a PC RGB signal in an analog digital converter (hereinafter, referred to as 'ADC'). The scaling unit 8 scales the digital RGB signal to match the display characteristics or the size of the LCD. In this case, the scaled signal is converted into an analog signal so as to be suitable for the LCD by a digital analog converter (DAC 10 or less). Meanwhile, as shown in FIG. 2, the gamma control unit 12 adjusts sufficient brightness characteristics so that the brightness characteristics are prevented from being lowered due to the transmission characteristics of the LCD which is difficult to identify gray scales in black. Accordingly, the gamma control unit 12 exhibits gamma characteristics as shown in FIG. 3 to correspond to the transmission characteristics of the LCD. In addition, the driver unit 14 drives with a level and inverted / non-inverted signal to match the characteristics of the LCD, and the sampling / holder unit 16 generates a signal for block driving according to the LCD characteristics and sends it to the liquid crystal panel. Allow an image to be displayed.

However, in the conventional method, even if the gamma correction is fully implemented to some extent, the screen correction in the dark portion requires a considerable amount of amplification, which leads to a problem that the image quality of the dark portion is deteriorated.

Accordingly, an object of the present invention is to provide an image quality correcting apparatus of a black screen configured to correct image quality on a dark screen.

1 is a view showing the configuration of a conventional image quality correction device.

2 is a characteristic diagram showing transmission characteristics of a liquid crystal panel;

3 is a characteristic diagram showing signal characteristics of a gamma control unit;

4 is a diagram illustrating a configuration of an apparatus for compensating for image quality of a black screen according to the present invention.

5 is a view for explaining the driving of FIG.

6 is a view for explaining a change in gray level according to the image quality correction of the black screen according to the present invention.

<Description of Symbols for Main Parts of Drawings>

2,22: Color decoder 4,42: Image processor

6,24: analog digital converter 8,46: scaling unit

10,40,48: Digital analog converter 12,50: Gamma control part

14,52: driver section 16,54: sampling / holder section

26: field memory and control unit 28: window processing unit

30: input signal level detector 32: gray level detector

34: white limit control unit 36: threshold level setting unit

38: black screen gray level expansion unit 56: brightness variable switch processing unit

In order to achieve the above object, an image correcting apparatus for a black screen according to the present invention includes a color decoder which separates a complex video signal into a luminance signal and a color difference signal, and converts a color difference signal and a digital analog converter separated from the color decoder into an analog signal. An image processor for processing the luminance signal into red, green, and blue signals, an analog digital converter for converting the red, green, and blue analog signals into a digital signal, and scaling the digital signal to match the size of the liquid crystal panel. A scaling unit, a digital analog converter for converting a digital signal into an analog signal, a gamma control unit for adjusting brightness characteristics of the liquid crystal panel, a driver unit for supplying a driving signal to drive the liquid crystal panel, and a LCD with sampling / holder for sampling and holding driving signal And a luminance signal separated by the color decoder is converted into a digital signal by the analog digital converter to store an image for one field, and to distribute the image stored in the field memory at predetermined time intervals. A control unit, an input signal level detector for detecting the level of the input signal distributed by the controller at a predetermined time interval, and a level for the black and white of the signal distributed by the input signal level detector at a predetermined time interval; A gray level detector to expand the black gray level so as to correspond to the black and white contrast of the signal input from the gray level detector, a gray level detector to expand the black gray level, and the input to correspond to the level of the luminance signal detected from the composite video signal By varying the brightness level of the signal detected by the signal level detector And a brightness variable switch processing unit supplied to the driver unit.

Other objects and features of the present invention other than the above object will become apparent from the description of the embodiments with reference to the accompanying drawings.

A preferred embodiment of the present invention will be described with reference to FIGS. 4 to 6.

Referring to FIG. 4, an apparatus for compensating image quality of a black screen according to the present invention includes a color decoder 22 for separating a complex video signal CVBS into a luminance signal Y and a color difference signal UV, and a color difference signal UV. And an image processing unit 42 for processing the luminance signal Y as an RGB signal, an ADC 24 for converting an analog RGB signal into a digital RGB signal, and a scaling unit for scaling the RGB signal to match the size of the liquid crystal panel ( 46), a DAC 48 for converting digital signals to analog, a gamma control unit 50 for adjusting the brightness characteristics of the liquid crystal panel, a driver unit 52 for driving the liquid crystal panel, and a liquid crystal panel driving signal A sampling / holder portion 54 for holding / holding is provided. Since the LCD output unit of the black screen image quality correction device according to the present invention has the same configuration as the prior art, a detailed description thereof will be omitted.

In addition, the black screen image quality correction apparatus according to the present invention includes an ADC 24 for converting a luminance signal Y into a digital signal, a field memory and a controller 26 for storing one field of image, and a field memory. A window processing unit 28 for distributing the stored images at predetermined time intervals, and an input signal level detection unit 30 for detecting the level of the input signal at predetermined time intervals. A gray level detector 32 for detecting the level of the input signal at a predetermined time interval, a white limit controller 34 for setting a white limit value so that a signal corresponding to one field does not exceed the white limit, and 1 The threshold level setting unit 36 for setting the threshold level for each field, the black screen gray level extending unit 38 for increasing the black gray level to correspond to the black and white ratio for each set time period, and the level of the input signal And a brightness variable switch processor 56 for varying the brightness level. An operation of the LCD input unit of the black screen image quality correcting apparatus according to the present invention will be described in detail. The luminance signal Y separated by the color decoder 22 is converted into a digital signal by the ADC 24. In addition, the field memory and the control unit 26 store image information for one field as shown in Fig. 5A from the digital luminance signal Y, and then store the image information under the control of the window processing unit 28. Make an appropriate time distribution. At this time, the time distribution for the stored image is shown in Fig. 5B. In this case, according to window setting and time distribution, the input signal level detector 30 reads the input level of the signal for each predetermined time period and performs two processes. This will be described in detail. One is to enable the flag signal (Flag) sent to the brightness variable switch processing unit 56 (On) or off (Off). The other is to send an appropriate direct current (DC) information value so that the white limit control unit 34 can determine the peak white value for the input signal in one field. On the other hand, the gray level detector 32 reads the current value ratios for the bright screen unit and the dark screen unit for a given time interval for each divided time period to obtain a level difference for black / white for each time period. In this case, as shown in Fig. 6A, the level difference with respect to black and white becomes a gray level corresponding to each time. When the reference gray level is set in this manner, the white limit controller 34 sets a white limit value so that the signal in one field does not exceed a certain white level according to the information sent from the input signal level detector. This is the maximum current value for the signal to be processed. In addition, the next signal after the white limit is determined is sent to the threshold level setting unit 36 in one field so that a certain threshold level is determined, and this signal is sent to the black screen gray level extending unit 38 so that the signal of FIG. As shown in FIG. 3, the gray level is increased by the set time zone. In this case, the black-to-white ratio is weighted to make the black ratio more black, and the smaller the black ratio is, the smaller the black ratio is, so that the applied eye can feel the bright and dark contrast difference even in the fine part of the dark screen. Done. After converting the signal into an analog signal through the DAC 40, the image processing unit 42 is properly matrixed with an RGB signal together with the color-processed color difference signal UV and output to the liquid crystal panel. Meanwhile, the brightness variable switch processing unit 56 drives the driver unit 52 to automatically adjust brightness at predetermined time intervals by a flag sent from the input signal level detection unit 30 according to the level of the input signal. Bright and clear images will be realized.

As described above, the black screen quality correcting apparatus according to the present invention has an advantage of improving the quality by correcting the picture quality on a dark screen.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (2)

A color decoder which separates a composite video signal into a luminance signal and a chrominance signal, and an image processor for processing the color difference signal separated by the color decoder and the luminance signal converted into an analog signal by a digital analog converter into red, green, and blue signals; An analog digital converter for converting the red, green, and blue analog signals into a digital signal, a scaling unit for scaling the digital signal to fit the size of a liquid crystal panel, a digital analog converter for converting a digital signal into an analog signal; A liquid crystal projector comprising a gamma control unit for adjusting brightness characteristics of a liquid crystal panel, a driver unit for supplying a driving signal to drive the liquid crystal panel, and a sampling / holder unit for sampling and holding the driving signal supplied from the driver unit. , A field memory for converting the luminance signal separated by the color decoder into a digital signal by the analog digital converter and storing one field of image; A control unit for distributing images stored in the field memory at predetermined time intervals; An input signal level detector for detecting a level of the input signal distributed by the controller at a predetermined time interval at predetermined time intervals; A gray level detector for detecting the level of the signal distributed by the input signal level detector at a predetermined time interval; A black screen gray level expansion unit for extending the black gray level so as to correspond to the black and white contrast of the signal input from the gray level detection unit; And a brightness variable switch processor for varying the brightness level of the signal detected by the input signal level detector to supply the driver to correspond to the level of the brightness signal detected from the composite video signal. Compensator. The method of claim 1, A white limit controller for setting a white limit value of a signal supplied from the input signal level detector so that a signal for one field supplied from the input signal level detector does not exceed a white limit; And a threshold level setting unit for setting a threshold level of the white limit value set by the white limit control unit.