KR100247085B1 - Contrast control device of image display - Google Patents

Abstract

The present invention relates to a contrast control apparatus for an image screen, comprising: a luminance / color signal separator (32) for separating luminance / color signals from an image IF signal from an IF processing module (30), and the luminance by an external contrast control signal. In a television having a main contrast adjusting section 44 for adjusting contrast for a signal, the contrast-adjusted luminance signal is sampled by the oscillation signal from the oscillator 48 to generate sampling results for a plurality of screen areas. A sampling unit 46, a modulation unit 50 for modulating the luminance signal of the sampling result, a sub-contrast control unit 52 for sub-contrast the modulated luminance signal for each screen region, and a sub-contrast adjustment for each screen region. The demodulated luminance signal is demodulated by the timing signal provided from the timing signal generator 56 and applied to the R / G / B matrix process of the TINT-adjusted color signal. Stand equipped with a demodulator (40) provided to virtually to adjust the contrast level individually for a plurality of screen areas are vertically divided.

Description

Contrast Control Device for Video Screen

The present invention relates to a contrast control apparatus of a video screen, and more particularly, to a screen according to a contrast adjustment amount or a peripheral illumination amount set by a viewer in a virtual vertical division of a video screen of a CRT apparatus into a plurality of screen areas. A contrast control apparatus for an image screen, in which contrast can be adjusted for each region.

As is well known, an image processing system represented by a television is essentially provided with a CRT device as a means for reproducing a video screen, and the CRT device is capable of receiving a broadcast video signal or an external video signal processed by an image processing system of a television. The display is processed by the contrast adjustment amount.

1 is a view showing an exemplary configuration of a contrast adjustment apparatus for a video screen applied to a general television. According to the same figure, the collector side of the horizontal output transistor 10 which switches ON / OFF in response to the horizontal drive signal applied from the horizontal drive so that the video signal processed by the operation of the television is reproduced in the CRT apparatus (not shown). A damper circuit portion 12 (consisting of a diode 14 and a capacitor 16) is connected, and a horizontal deflection coil 18 is connected, and the horizontal deflection coil 18 of the horizontal output transistor 10 is connected. One end of the flyback transformer 20 is connected to the rear, and the flyback transformer 20 obtains an automatic brightness limit (ABL) signal for the CRT device. In addition, the control unit 22 is connected to the ABL signal, and the control unit 22 appropriately adjusts the level of the ABL signal based on an external contrast (or luminance) control signal CS to achieve contrast. ) And a brightness adjustment signal are applied to an image processing processor (not shown).

Therefore, according to the contrast control apparatus of the conventional video screen shown in FIG. 1, when the viewer applies the contrast / luminance control signal CS having a predetermined level to the controller 22, the controller 22 outputs a horizontal output. In response to switching ON / OFF of the transistor 10, the level of the ABL signal obtained from the flyback transformer 20 is received and an adjustment signal of contrast (CONTRAST; and / or brightness) for the CRT device is received. And the contrast of the video screen displayed on the CRT apparatus is adjusted to the set value.

However, in the contrast control apparatus of the video screen illustrated in FIG. 1, the control unit 22 automatically adjusts the contrast (and / or luminance) level set by the control signal CS based on the ABL signal level. However, since the adjustment of the contrast is applied equally to the whole part of the image screen, if a polarization component is projected on the left or right side of the CRT apparatus, for example, the visual effect on the image screen of the part where the polarization component is projected is not. Will be degraded. In addition, when the contrast is lowered in a part of the video screen, the contents of the video screen cannot be accurately understood. In this state, even when the viewer tries to increase the contrast, the contrast of the video screen is reduced. As the overall increase, the overall visual sense of the screen deteriorates.

In recent years, when a relatively high luminance polarization component is projected from the left or right side of the CRT apparatus, the screen of the CRT apparatus having a high illuminance detected by detecting peripheral illuminance in order to improve visibility of the video screen ( A method of partially half-blanking the video screen (24a in FIG. 1b; 24b in FIG. 1b) displayed on the left or the right side on 24 in FIG. Although considered, the half blanking processing method affects the original video signal, which is disadvantageous.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its main purpose is to adjust contrast for another screen area based on the contrast of a specific screen area while virtually vertically dividing the video screen of the CRT apparatus into a plurality of screen areas. It is to provide a contrast control apparatus for a video screen.

Another object of the present invention is to detect a peripheral illumination level in a virtual vertical division of a video screen of a CRT device into a plurality of screen areas, and to optimally contrast the screen area that is virtually divided according to the detected illumination level. It is to provide a contrast control apparatus for a video screen to be adjusted.

In order to achieve the above object, according to a first embodiment of the present invention, a luminance / color signal separation unit for separating luminance / color signals from an image IF signal from an IF processing module, and the luminance signal by an external contrast control signal. A television having a main contrast control unit for adjusting contrast to a sampling unit, comprising: a sampling unit for sampling the contrast-adjusted luminance signal by an oscillation signal to generate sampling results for a plurality of screen regions; A modulator for modulating the luminance signal, a sub-contrast controller for adjusting the modulated luminance signal for each screen region, and a TINT-adjusted demodulation of the luminance signal with sub-contrast control for each screen region by a timing signal provided from a timing signal generator. Demodulation unit for applying to R / G / B matrix processing of color signal A contrast control unit of the image screen configured than are provided.

Further, in order to achieve the above another object, according to a second preferred embodiment of the present invention, in the television having a main contrast control unit for adjusting the contrast with respect to the luminance signal by an external contrast control signal, the main contrast adjustment A mode setting button of the remote controller for selecting a contrast automatic adjustment mode for the received luminance signal and an adjustment of the contrast by the main contrast adjustment unit on the basis of the ABL signal detected by the ABL level detection unit. A control unit for controlling illumination-contrast contrast control of a plurality of screen regions of a video signal, a modulation unit for performing modulation on the main contrast-adjusted luminance signal, and a left side and a right side of a CRT apparatus, which are installed around the video screen. First and second illuminance detecting means for detecting illuminance, Contrast control data memory for each screen area corresponding to the peripheral illuminance of the video screen under the control of the control unit, and the table area of the brightness signal modulated by the modulator by the contrast control data for each screen area. Sub-contrast control unit for adjusting the contrast of each star,

There is provided a contrast control apparatus for an image screen including a demodulation unit for demodulating a luminance signal of each sub-contrast adjusted for each screen region in the illuminance adaptation method.

According to the contrast control apparatus of a video screen according to the present invention having the above-described configuration, the video screen of the CRT apparatus is virtually vertically divided into a plurality of areas so as to approximate the contrast level of the reference screen area or the level set by the viewer. Contrast can be adjusted for each screen area.

1A is a block diagram of a contrast control apparatus for a video screen according to a conventional example;

1B is a view showing an on-screen display half blanking processing state by a contrast control apparatus of an image screen according to a conventional example;

2 is a block diagram showing the configuration of a contrast control apparatus for a video screen according to a first embodiment of the present invention;

3 is a view for explaining a contrast control state for each screen region by the contrast control apparatus for an image screen according to the first embodiment of the present invention;

4 is a block diagram of a contrast control apparatus for a video screen according to a second embodiment of the present invention;

FIG. 5 is a diagram for explaining contrast control states for each screen area of an illuminance adaptation method by a contrast control apparatus for an image screen according to a second exemplary embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10: horizontal output transistor, 20: flyback transformer,

22: control unit, 30: IF processing module,

32: luminance / color signal separator, 34, 42: analog-to-digital converter,

36: TINT controller, 38: digital-to-analog converter,

40: R / G / B matrix, 44, 76: main contrast control unit,

46: sampling part, 48: oscillation part,

50,78: modulator, 54,82: demodulator,

52,52a-52n; 80, 80a-80d: sub-contrast control unit,

56: timing signal generator.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of a contrast control apparatus for a video screen according to a first embodiment of the present invention. In the figure, reference numeral 30 denotes an IF processing module for converting and processing a broadcast signal of a channel tuned by a tuner (not shown) into a predetermined intermediate frequency (IF) signal, and 32 denotes an IF conversion processing in the IF processing module. A luminance / color signal (Y / C) separation section for separating the luminance signal (Y) and the color signal (C) from the image IF signal. 34 denotes an analog-digital converter for digitally converting the color signal C, and 36 denotes a TINT for adjusting the TINT for the digitally converted color signal C based on the TINT control signal provided from the controller 22. FIG. 38 denotes a digital-to-analog converter for reconverting (R / G / B) the color signal adjusted by TINT in the TINT controller 36 to an analog signal, and 40 denotes the R / G / B signal. An R / G / B matrix for generating color components based on the luminance signal Y described later is shown.

42 denotes an analog-digital conversion unit for digitally converting the luminance signal Y separated by the luminance / color signal separation unit 32, and 44 denotes the digital based on the contrast control signal applied from the control unit 22. The main contrast control unit for adjusting the contrast with respect to the converted luminance signal, 46 denotes the oscillation unit 48 oscillates the luminance signal adjusted to the contrast level set by the control unit 22 in the main contrast control unit 44 A sampling unit for sampling processing in accordance with a predetermined clock signal to be displayed is shown, and 50 denotes a modulation unit for modulating the luminance signal Y sampled by the sampling unit 46. In addition, 52 denotes a sub-contrast control unit which is connected to the modulator 50 to perform sub-contrast adjustment for each screen area of the CRT device, and the sub-contrast control unit 52 displays an image screen of the CRT device. 'a'-If the area is divided into 'n', the first to nth sub-contrast adjusting units 52a to 52n are provided for adjusting the sub-contrast for each screen area. Here, when the contrast of a specific screen area is determined as a reference, the sub-contrast control unit 52 increases or decreases the contrast level of the corresponding screen area so that the contrast of the other screen area is adjusted to the contrast level of the reference screen. Will work. In addition, the reference screen area is set by applying a sampling result for each screen area sampled by the sampling unit 46 to the control unit 22 so that the control unit 22 has a screen area having an average contrast level. The reference area may be set so that contrast adjustment by the first to nth subcontrast adjusting units 52a to 52n is performed. On the other hand, according to the present invention, the screen region divided virtually vertically may be designated by the viewer so that the contrast level of only the designated screen region is increased / decreased.

In FIG. 2, reference numeral 54 denotes a timing signal provided by the timing signal generator 56 as a contrast control signal for each screen area controlled by the first to nth sub-contrast controllers 52a to 52n. Demodulation is sequentially performed based on the < Desc / Clms Page number 5 >

Next, the operation of the contrast control apparatus for the video screen according to the first embodiment of the present invention will be described in detail with reference to FIGS. 3A to 3F.

First, referring to FIG. 3 (a), the screen 24 ′ of the CRT apparatus is virtually vertically divided into a plurality of screen areas a-n, and an image of one frame corresponds to the screen areas a-n. The signal is also virtually divided in the form shown in FIG. In this state, if the TINT setting signal (or the reference TINT setting signal) and / or the contrast setting signal (or the reference contrast setting signal) are supplied to the control unit 22 from the remote controller, the control unit 22 adjusts the TINT adjustment. The TINT control signal and the contrast control signal are applied to the unit 36 and the main contrast control unit 44.

The IF signal processed by the IF processing module 30 is converted into a luminance signal Y and a color signal C by the luminance / color signal separator 32, and the color signal C is analog-. It is digitally converted by the digital conversion unit 34 and applied to the TINT control unit 36. The TINT control unit 36 applies the TINT control signal from the control unit 22 with respect to the digitally converted color signal C. Based on this, the TINT is adjusted. Then, the TINT-adjusted color signal C is applied to the digital-analog converter 38 and analog converted and then applied to the R / G / B matrix 40.

Meanwhile, the luminance signal Y separated by the luminance / color signal separation unit 32 is digitally converted by the analog-digital conversion unit 42 and applied to the main contrast control unit 44, and the main contrast control unit ( In 44, the brightness signal Y is adjusted to the sampling unit 46 after the contrast level is adjusted based on the contrast control signal applied from the controller 22. The sampling section 46 samples the oscillation signal applied from the oscillation section 48 with respect to the contrast-adjusted luminance signal C, i.e., a section corresponding to the screen regions shown in Figs. 3A and 3B. It is executed (see FIG. 3 (c)) and applied to the modulator 50. The modulator 50 modulates the contrast levels of the sampled screen regions a-n and sequentially applies them to the first to nth sub-contrast adjusters 52a-52n of the sub-contrast adjuster 52. Accordingly, the first to nth sub-contrast adjusting units 52a to 52n adjust the contrast level of the other screen areas b to n based on a specific screen area (for example, 'a'). Done. The reference screen area may be set by, for example, when the viewer sets a specific screen area for adjusting the contrast, the sub-contrast control unit corresponding to the screen area is designated by the control unit 22. Sampling for each screen area (a-n) sampled by the sampling section 46, or executed in such a manner as to apply the contrast level processed by the negative part to the adjustment of other sub-contrast levels to perform differential increase and decrease processing. The result is applied to the control unit 22 so that the control unit 22 sets the screen area having the average contrast level as the reference screen area, and sets the contrast level processed by the sub-contrast control unit corresponding to the screen area to another sub. If it is applied to the contrast control unit and the sensitizing It is straight.

Thus, for example, when the screen area 'a' is set to the contrast level of the reference screen area, the contrast level of the screen area 'b' is slightly higher while the contrast level of the screen area 'c' is slightly lower (detected in FIG. 3). (c)), the contrast level of the reference screen area 'a' passes through the corresponding sub-contrast controller 52a at that level (see FIGS. 3 (d) and (e)). The contrast level of 'b' is reduced (see (d) and (e) of FIG. 3) while the contrast level of the screen area 'c' is increased (see (d) and (e) of FIG. 3). For the contrast level of the remaining screen area d-n, the increase / decrease processing is executed in the corresponding sub-contrast adjusting units 52d-52n based on the contrast level of the screen area 'a'.

Subsequently, a luminance signal of each screen area a-n sub-contrast adjusted by the first to n-th sub-contrast controllers 52a to 52n of the sub-contrast controller 52 is applied to the demodulator 54. And are sequentially rearranged based on the timing signal provided from the timing signal generator 56 to be demodulated to be reconstructed as a luminance signal of an image screen and applied to the R / G / B matrix 40. In the G / B matrix 40, the contrast-adjusted luminance signal for each screen area of the color signal component R / G / B is applied and processed to the CRT device, so that an image screen displayed on the CRT device is eventually obtained. In contrast, contrast is adjusted for each virtually divided screen area.

4 is a block diagram of a contrast control apparatus for a video screen according to a second exemplary embodiment of the present invention. According to the second embodiment, when the peripheral illuminance is detected at predetermined positions on the left and right sides of the CRT apparatus, and when a large amount of polarization components are relatively injected, automatic contrast adjustment is performed on the screen area where the polarization components are projected. The process of making it possible is assumed.

That is, reference numeral 60 in FIG. 4 denotes a remote controller for selectively executing the overall functions of the corresponding television, and the remote controller 60 is provided with a mode setting button 60a for setting the contrast automatic adjustment mode. 62 is a control unit for controlling to execute a selective function of the television according to the control signal applied from the remote control 60, the control unit 62 is contrasted by the mode setting button 60a of the remote control 60 When the automatic mode is set, control is performed to automatically adjust the contrast of the screen area on which the polarization component is projected based on the peripheral illumination detection.

66 denotes a flyback transformer 66 (see FIG. 1) for generating various voltages used for a corresponding television, and 68 denotes a digital conversion of an ABL signal obtained from the flyback transformer 66 and applied to the controller 62. An ABL level detection unit is shown. In addition, 70a and 70b indicate first and second illuminance sensing units installed at predetermined positions on the left and right sides of the CRT apparatus to detect peripheral illuminance, and 72a and 72b correspond to corresponding first and second illuminance detecting units ( The first and second level detection / conversion units for converting the peripheral illuminance detected by 70a and 70b into digital levels and applying them to the control unit 62 are shown. 74 shows a contrast adjustment data memory in which contrast level data which should be controlled by the controller 62 is stored in response to the peripheral illumination sensed by the first and second illuminance sensing units 70a and 70b. Similar to the main contrast adjusting section 44 shown in Fig. 2, the main contrast adjusting section adjusts the contrast of the luminance signal Y under the control of the control section 62, and 78 represents the contrast in the main contrast adjusting section 78. A modulator for modulating the adjusted luminance signal Y, where 80 is the first to fourth sub-contrast controller 80a to 80d corresponding to the virtually vertically divided screen region (four-screen region). ) Denotes a sub-contrast control unit, and 82 denotes an R / G / B mat by demodulating the luminance signal Y, which is contrast-adjusted for each screen area, in the sub-contrast control unit 80. It represents parts of the demodulation to be applied to the switch (not shown).

Next, the operation of the contrast control apparatus for the video screen according to the second embodiment of the present invention having such a configuration will be described in detail with reference to FIG.

First, in the present embodiment, the video screen of the CRT apparatus is virtually divided into four screen areas (a-d), and the contrast adjustment data memory 74 writes a contrast adjustment level corresponding to the peripheral illumination in the form of a data table. For example, the contrast control level is relatively low contrast is detected on the screen area with a high peripheral illumination in response to the ambient illumination detected by the first and second illuminance detection unit (70a, 70b). It is created in such a way as to be reduced toward the contrast on the screen area side (see FIG. 5 (c)), or the contrast on the screen area side with high peripheral illumination is reduced by a certain level, while the contrast area of the screen area with relatively low ambient illumination is reduced. Contrast is created in such a way as to increase by a certain level.

In this state, the controller 62 controls the contrast setting signal (or previously set) by the remote controller 60 when the automatic adjustment mode of contrast is not set by the mode setting button 60a of the remote controller 60. The contrast control signal is applied to the main contrast control unit 76 according to the contrast signal to control the overall screen area a-d to be uniformly contrast adjusted.

In the meantime, if the level of the ABL signal provided from the flyback transformer 66 is detected by the ABL level detector 68 and applied as a digital signal, the controller 62 controls the main contrast control unit when the ABL level is changed. In contrast to 76, when the ABL signal is decreased, the contrast is controlled to increase, while when the ABL signal is increased, the contrast is reduced. Therefore, the luminance signal Y, which is contrast-adjusted in the main contrast control unit 76, is applied to the R / G / B matrix through the modulation unit 78, the sub-contrast adjustment unit 80, and the demodulation unit 82. Thus, the contrast of the color signal is uniformly adjusted on the entire video screen.

In contrast, when the automatic adjustment mode of contrast is set by the mode setting button 60a of the remote controller 60, the controller 62 is detected by the first and second illuminance sensing units 70a and 70b. The level detection / conversion unit 72a, 72b performs the control of contrast adjustment on the plurality of virtual vertically divided screen areas a-d based on the peripheral illumination applied digitally.

That is, for example, when the illuminance detected by the first illuminance detecting unit 70a is higher than the illuminance detected by the second illuminance detecting unit 70b, that is, when the left polarization component of the CRT apparatus exists, Reduction processing so that the contrast level for the screen area (b) adjacent to the screen area (a) of the video screen displayed on the screen is equal to the contrast level of the screen areas (c, d) (see Figs. 5 (a) and (b)). You have to. Alternatively, the contrast level of the screen areas (a, b) in which the polarization components exist is reduced by a certain amount, while the contrast levels of the screen areas (c, d) must be increased by a certain amount to be averaged.

Therefore, when the illuminance detected by the first illuminance detecting unit 70a is higher than the illuminance detected by the second illuminance detecting unit 70b, the control unit 62 shows the illuminance illustrated in FIG. 5 (d). From the relation of the sub-contrast adjustment data with respect to the sub-contrast adjustment data, for example, it is determined that the sub-contrast adjustment is necessary by the data 'I'. The adjustment data 'I' is read and applied to the first to fourth sub-contrast adjusting units 80a to 80d of the sub-contrast adjusting unit 80, and accordingly the first and fourth sub-contrast adjusting units 80a. -80d) shows the contrast with respect to the screen area 'a' in the first sub-contrast controller 80a corresponding to the screen area a with high peripheral illumination based on the data 'I' of the data table of FIG. Even if On the other hand, the screen area 'b' adjacent to the screen area 'b' is processed so that the contrast level is slightly reduced in the corresponding second sub-contrast adjusting unit 80b, and is applied to the remaining screen areas c and d. The third and fourth sub-contrast adjusting units 80c and 80d corresponding to the sub-contrast are adjusted to a level corresponding to the data 'I' (see FIGS. 5A and 5B).

On the other hand, the controller 62 shows the illuminance detected by the first illuminance sensor 70a when the illuminance detected by the second illuminance sensor 70b is lower than that shown in FIG. From the relation of the sub-contrast adjustment data with respect to the illuminance, it is determined that the sub-contrast adjustment is necessary, for example, by the data 'III', and according to the determination result, the control unit 62 corresponds to the corresponding contrast adjustment data memory 74 from the sub-contrast adjustment data. The contrast adjusting data 'III' is read and applied to the first to fourth sub-contrast adjusting units 80a to 80d of the sub-contrast adjusting unit 80, and accordingly the first and fourth sub-contrast adjusting units ( 80a to 80d show that the fourth sub-contrast controller 80d corresponding to the screen area d having a high peripheral illuminance based on the data 'III' of the data table of FIG. Contrast On the other hand, the screen area 'c' adjacent to the screen area 'd' is processed such that the contrast level is slightly reduced in the corresponding third sub-contrast adjusting unit 80c, and the remaining screen areas a and b are processed. The subcontrast is adjusted to a level corresponding to the data 'III' in the first and second sub-contrast adjusting units 80a and 80b corresponding to (see FIGS. 5A and 5B). .

Subsequently, the contrast level of the screen area a-d adjusted by the first to fourth sub-contrast adjusting units 80a to 80d of the sub-contrast adjusting unit 80 is demodulated by the demodulator 82 to be R. When applied to the / G / B matrix, the contrast is applied to the CRT device while the contrast of the color signal (R / G / B) is adjusted. Accordingly, the contrast per region of the video screen displayed on the CRT device can be adjusted. do.

According to the present invention, when the peripheral illuminance sensed by the first and second illuminance detectors 70a and 70b has a mutual difference, the contrast is reduced by a predetermined level for the screen region with high illuminance while the illuminance is low. For the screen area, a data table for increasing the contrast by a certain level may be stored in the contrast adjusting memory 74 so that the contrast for each screen area based on the data table is adjusted.

In addition, the present invention is not limited to the above-described embodiment so that a viewer can designate a specific screen region for the virtually divided screen region by, for example, 10-keys of the remote controller, so that the contrast level can be adjusted only for the specific screen region. Of course, the control is also possible.

As described above, according to the contrast control apparatus of a video screen according to the present invention, the video screen displayed on the CRT device is virtually divided into a plurality of screen areas so that the contrast level can be adjusted around the reference screen area or the surrounding area. By allowing adjustment based on the illuminance level, the contrast of the video screen can be maintained substantially uniform, which not only improves the vision protection function of the viewer, but also eliminates the half blanking process that is adapted to the ambient illuminance. It is possible to eliminate the adverse effect of the image quality.

Claims (7)

A luminance / color signal separator 32 for separating luminance / color signals from the image IF signal from the IF processing module 30, and a main contrast controller 44 for adjusting contrast with respect to the luminance signal by an external contrast control signal. In television with), A sampling unit 46 for sampling the contrast-adjusted luminance signal by the oscillation unit 48 to generate sampling results for a plurality of screen regions; A modulator 50 for modulating the luminance signal of the sampling result; A sub-contrast controller 52 for controlling sub-contrast of the modulated luminance signal for each screen region; A demodulator 40 which demodulates the sub-contrast adjusted luminance signal for each screen region into a timing signal provided from the timing signal generator 56 and provides it as a contrast signal applied to the R / G / B matrix processing of the TINT-adjusted color signal. Contrast control device for a video screen, characterized in that it is configured to. 2. The sub-contrast control unit (52) of claim 1, wherein the sub-contrast control unit (52) includes a plurality of first to n-th sub-contrast control units (52a to 52n) corresponding to the screen area. And a screen area having one average contrast level is set as the reference area for controlling the sub-contrast of the corresponding screen area by 52n). 2. The first to nth sub-contrast adjusters 52a to 52n of the sub-contrast adjuster 52 based on sampling results of the plurality of screen regions sampled by the sampling unit 46. And a control unit (22) for setting the contrast level for one screen area to be processed as a reference level to perform contrast adjustment for the other screen area. In a television equipped with a main contrast control unit 76 for adjusting the contrast of the luminance signal by an external contrast control signal, A mode setting button 60a of the remote controller 60 for selecting a contrast automatic adjustment mode for the main contrast adjusted luminance signal; Based on the ABL signal detected by the ABL level detection unit 68, the contrast control by the main contrast control unit 76 is controlled. In the automatic adjustment mode, the illuminance-adaptive sub-contrast of a plurality of screen regions of the video signal is controlled. A control unit 62 for controlling the control to be executed; A modulator 78 for performing modulation on the main contrast-adjusted luminance signal; First and second illuminance detection means (70a, 72a; 760b, 72b) installed on the left and right sides of the CRT apparatus to detect peripheral illuminance of a video screen; Contrast adjustment data memory 74 which stores the contrast adjustment data for each screen region corresponding to the peripheral illuminance of the video screen under the control of the controller 62 and stores them in a table. A sub-contrast controller 80 for adjusting the contrast for each screen region of the luminance signal modulated by the modulator 78 by the contrast control data for each screen region; And a demodulation unit (82) for demodulating the luminance signal of the contrast level adjusted for each screen region by the illuminance adaptation method in the sub-contrast adjustment unit (80). 5. The apparatus of claim 4, wherein the sub-contrast controller 80 includes a plurality of sub-contrast controllers 80a to 80b corresponding to the screen area, and the contrast control data memory 74 includes the plurality of sub-contrast controllers. Contrast control device for a video screen, characterized in that the contrast control unit (80a-80n) is stored so that the contrast level is relatively reduced for the screen area of the high peripheral illumination. The contrast control data memory (74) according to claim 4 or 5, wherein the plurality of sub-contrast adjusting units (80a to 80n) reduce a certain amount of contrast level for a screen area of high ambient illumination, while low ambient illumination. The contrast control apparatus for a video screen, characterized in that data is stored so that the contrast level is increased by a certain amount so that the contrast level of the video screen is constant. 5. The contrast control apparatus for a video screen according to claim 4, characterized in that a screen region as an object of adjustment of the contrast level with respect to the detected peripheral illumination is designated by said remote controller (60).

Images