CN117059041A - LCD backlight control display system - Google Patents

Abstract

The invention provides an LCD backlight control display system, which comprises a front LCD panel, a rear LCD panel, an LED backlight driving unit, a block brightness value determining device, an LED driving signal generator, a gray image data generator and an RGB image signal generator. The front LCD panel (RGB panel) of the present invention is used to display RGB images, and the rear LCD panel is located behind the front LCD panel to display gray images to adjust the amount of backlight transmission. The block luminance value determining means adjusts the luminance of the LED backlight driving unit by the block luminance obtained by the block luminance value determining means. The LED backlight driving unit is used for driving the brightness of each dimming block. And a gray image data generator generating a second gray image signal by the first gray signal and controlling a brightness level of each pixel of the rear panel gray image. An RGB image data generator for adjusting the brightness level of each sub-pixel of the image signals R, G and B. By the backlight system scheme, the contrast ratio of image display can be effectively improved.

Description

LCD backlight control display system

Technical Field

The invention belongs to the technical field of liquid crystal display equipment, and particularly relates to an LCD backlight control display system.

Background

With the development and progress of display technology, high brightness and high dynamic range HDR display technology is becoming the dominant direction of current display technology. In the organic EL panel display process, the display contrast can reach 10000000 at maximum: 1. however, in the conventional LCD display device, since the display of the image is mainly achieved by the backlight source penetrating the LCD panel, the gray scale characteristics of the black area are poor, and the actual brightness is higher than the ideal brightness, so that the contrast ratio of the image is not high, for example, only 1200:1 is achieved. In response to this problem, the present invention proposes a backlight control display scheme of a dual LCD panel to effectively improve the contrast ratio of an LCD image display device. In the image display device of the present invention, the front LCD panel (RGB panel) is used to display RGB images, and the rear LCD panel is used to display gray-scale images to adjust the amount of backlight transmission, in this way, the contrast ratio of image display can be effectively improved.

Disclosure of Invention

In the technical scheme of area dimming in the traditional scheme, when a dimming block of an image comprises a high-brightness area and a low-brightness area, the contrast of display equipment is obviously reduced.

In order to solve the above-described problems, the image display scheme of the present invention includes a front LCD panel for displaying RGB images, a rear LCD panel located behind the front LCD panel for displaying gray-scale images, and the front LCD panel and the rear LCD panel are irradiated with light to reduce the brightness of each image area block. The block brightness value determining device is used for determining the brightness of each block according to the input RGB image signals;

and a backlight driving signal generator driving the LED backlight driving unit to adjust the brightness of the backlight block according to the brightness of each block and the input RGB image signal. A first gray-scale image signal of a pixel is generated for a display image data signal on a preceding LCD according to an inputted maximum luminance and block luminance adjusting unit of a sub-pixel of each pixel. The gray image data generator generates a second gray image signal of the pixel according to the first gray image signal for controlling a brightness level of the gray image displayed in the rear LCD panel block. The invention also includes an RGB image data generator for adjusting the brightness level of each sub-pixel of RGB.

In one embodiment of the present invention, the block luminance value determining means extracts the maximum luminance among luminances of sub-pixels in each block of the input RGB image signal by the maximum luminance extractor. The block luminance value determining apparatus further includes an applicable value determiner that determines the luminance of the block based on the maximum luminance.

Further, in one embodiment of the present invention, the gray image data generator takes the maximum luminance of the sub-pixel of each pixel of the input RGB image signal as the representative value of the gray image signal. And, the gray image data generator further includes a gray converter converting the first gray image signal and a level converter converting the first gray image signal into the second gray image signal.

Further, in one embodiment of the present invention, the gray image data generator may determine a brightness level of the gray image of the pixel in the dimming block, when the block brightness determined by the block brightness value determining means is lower, the brightness level of the gray image signal of the pixel in the dimming block.

In one embodiment of the present invention, in the RGB image data generator, the lower the luminance of the first gray image signal generated by the gray image data generator, the lower the luminance level of each sub-pixel of the RGB image signal.

In one embodiment of the present invention, the RGB gray scale is used to correct the gray scale of the RGB image signal, the brightness level of which has been adjusted by the RGB image data generator, and the output characteristic of the LCD panel before being matched by the converter (the correction formula is OETF photoelectric conversion, GAMMA correction may be used, the output value=gamma power of the input value, and the selected GAMMA value is different according to the characteristics of the panel).

Further, in one embodiment of the present invention, in order to further correct the gray scale, the gray scale of the above-mentioned second gray scale image signal generated by the gray scale image data generator is matched with the output characteristic of the rear LCD panel through the gradation converter.

Further, the image display device of the present invention includes a front LCD panel displaying RGB image signals and a rear LCD panel displaying gray-scale images located behind the front LCD panel, and a backlight driving unit implementing illumination of the front and rear LCD panels and adjusting brightness of each backlight block. The first gray-scale image signal is generated according to the maximum brightness of the sub-pixel of each pixel of the input RGB image, and the brightness of each block is determined by the first gray-scale image signal. The backlight driving unit adjusts the brightness of the block according to the brightness determined by the brightness determining means. The block brightness determining device realizes the determination of the brightness level of the gray image. The blocks of the rear LCD panel are controlled by the first gray-scale image signal. The gray image signal generator generates a second gray image signal based on the first gray image signal. The invention also includes an RGB image data generator for adjusting the brightness level of each sub-pixel of RGB.

Further, the block luminance value determining means uses the maximum luminance of the sub-pixel of each pixel of the input RGB image signal as a representative value of the gradation image signal. The maximum extractor extracts mainly the maximum brightness of the pixels in each block of the first gray image signal. The applicable value determiner is used for determining the brightness of the block according to the maximum brightness.

Further, in one embodiment of the present invention, the gray image data generator includes a level shifter converting the first gray image signal into the second gray image signal.

In one embodiment of the present invention, the gray image data generator may determine a brightness level of the gray image of the pixel in the dimming block, when the block brightness determined by the block brightness value determining means is lower, the brightness level of the gray image signal of the pixel in the dimming block.

Further, in the RGB image generator, the lower the luminance of the first gray image signal generated by the gray image data generator, the higher the luminance level of each sub-pixel of the RGB image signal.

The RGB gray scale is used to correct the gray scale of the RGB image signal, the brightness level of which has been adjusted by the RGB image data generator, through the converter to match the output characteristics of the front LCD panel.

To further correct the gradation, the gradation of the above-described second gradation image signal generated by the gradation image data generator is matched with the output characteristics of the rear LCD panel by a gradation converter.

Further, the present invention may add a delay circuit before or after the RGB image data generator.

Further, the image display method of the present invention includes a front LCD panel displaying RGB images, a rear LCD panel behind the front LCD, which implements gray image display, and an LED backlight driving unit behind the rear LCD panel, which adjusts the brightness of each backlight block. The LED backlight driving unit is capable of adjusting the brightness of each of the plurality of blocks according to the input RGB image signals. The luminance of each block is determined based on the maximum luminance of the sub-pixel of each pixel of the RGB image signal, and a second gray image signal is generated to control the luminance level of the gray image displayed on the block.

Compared with the prior art, the technical scheme provided by the invention has the following technical effects:

the invention can effectively solve the problem of contrast reduction caused by the inclusion of a high brightness area and a low brightness area in the dimming block by adjusting the brightness level of each sub-pixel of the image and generating a gray image signal which controls the brightness level of the gray image displayed on the rear LCD panel according to the brightness of each block.

Drawings

The overall architecture of the system of fig. 1 is shown in block diagram form.

Fig. 2 is a block diagram of a signal processing unit of the image display device according to the first embodiment.

Fig. 3 is a block diagram of a signal processing unit of the image display device according to the second embodiment.

Fig. 4 is a block diagram of a signal processing unit of the image display device according to the third embodiment.

Detailed Description

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present invention and are not to be construed as limiting the present invention.

As shown in fig. 1, the image display device 1 includes a front LCD panel 2, a rear LCD panel 3, and an LED backlight driving unit 4. The front LCD panel 2 is mainly used to display RGB images, and the rear LCD panel 3 is disposed behind the front LCD panel 2 and superimposed on the front LCD panel 2 to display gray images. The rear LCD panel 3 is different from the front LCD panel 2 in that the rear panel has no color filters. The LED backlight driving unit 4 is located behind the rear LCD panel 3. The LED dimming block of the LED backlight driving unit 4 is a rectangular block generally including a plurality of LED beads, and each dimming speed corresponds to an image block of the input RGB. The LED backlight driving unit 4 can independently adjust the brightness of the dimming blocks, so as to realize the effect of local dimming. As described above, the dimming block BL of the LED backlight driving unit 4 includes a plurality of pixels, and it is possible to adjust the luminance of each pixel of the gradation image of the rear LCD panel 3 and to realize the adjustment of the luminance of each of the three RGB sub-pixels on the front LCD panel 2. In the present specification, the luminance described by the front LCD panel 2 and the rear LCD panel 3 refers to the transmittance in the front LCD panel 2 and the rear LCD panel 3.

As shown in fig. 2, a block diagram of a signal processing section in a first embodiment of the present invention. The signal processing unit outputs driving signals of the front LCD panel 2, the rear LCD panel 3, and the LED backlight driving unit 4. Specifically, the signal processing unit receives the front LCD panel 2 signal and the rear LCD panel 3 signal via EOTF (electro-optical transfer function) based on RGB image signals R, G and B having a linear relation with luminance, and generates signals for LED driving. The signal processing unit includes a block luminance value determining device 20, a first delay circuit 21, a gradation image data generator 22, an edge holding circuit 23, a gradation level converter 24, an RGB image data generator 25, a second delay circuit 26, an RGB level converter 27, a third delay circuit 28, and an LED driving signal generator 29 (delay circuit). The block luminance value determining device 20 determines a luminance value of each dimming block (pixel block) of the local dimming based on the RGB image signals R, G and B. In one embodiment of the present invention, the number of the dimming blocks for local dimming in the image display device is tens to hundreds or even thousands, and each block contains thousands of pixels. The block luminance value determining apparatus 20 includes a maximum value extractor 200 and an applicable value determiner 201.

The maximum extractor 200 mainly determines the brightness extraction maximum backlight brightness BLmax of the dimming block according to the values of R, G, B sub-pixels of the RGB image. In one embodiment of the present invention, it is assumed that the luminance value controlled by each backlight LED bead block is Lj (=l 1, L2,..once., ln) and the RGB image signal has 12-bit (4096) gray scale. When n=4, the brightness value of the lamp bead block can be controlled in four stages, and the brightness value of the LED lamp bead block in each stage is: l1=1023, l2=2047, l3=3071, l4=4095. In one embodiment of the present invention, when R is 1020, which is the highest luminance among the three sub-pixel values of all RGB image signals R, G, B in the dimming block, the maximum value BLmax of the dimming block is 1020. Similarly, when the highest luminance of B among the three sub-pixel values of all the RGB image signals R, G, B in the dimming block is 3000, the maximum value BLmax of the dimming block is 3000.

The applicable value determiner 201 determines the block brightness value blu in the dimming block from the maximum value BLmax. Specifically, when the maximum value BLmax of the dimming block, the minimum value Lj where blmax+.lj is determined as the block luminance value BLum. In the above example, lj is L1 (1023), L2 (2047), L3 (3071), L4 (4095). In one embodiment of the present invention, when the maximum value BLmax of the dimming block is 1020, the block brightness value BLum is determined as L3 (1023). Further, when the maximum value BL max of the dimming block is 3000, the block luminance value blu is determined as L3 (3071).

The first delay circuit 21 performs a first delay on the RGB image signal R, G, B. The purpose of the first delay is to compensate for the delay in the determination of the block luminance value blu in the block luminance value determination means 20. The first delay described makes it possible to match the timings of the grayscale image signal W and the block luminance value blu in the level shifter 222 of the grayscale image data generator 22 described later. The RGB image signals are subjected to a first delay to obtain RGB image signals R1, G1, B1. The gradation image data generator 22 obtains gradation image signals W and W1 from the RGB image signals R1, G1, and B1. The gray image data generator 22 includes a gray converter 221 and a level converter 222.

The gray-scale converter 221 receives RGB image signals R1, G1, B1 from the first delay circuit 21, and converts the maximum value of the three sub-pixel values (luminance) of R1, G1, B1 into a gray-scale image signal W as a representative value. The level shifter 222 converts the gray image signal W into the gray image signal W1 by the block brightness value blu in the dimming block, and the conversion formula is as follows: w1= (Ln/Blum) ×w. The grayscale image signal W1 is a signal for controlling the brightness level of the grayscale image displayed on the dimming block of the panel 3. When the brightness of each dimming block determined by the block brightness value determining means 20 is low, the level shifter 222 will increase the brightness level of the gray-scale image signal of the pixels in the dimming block. In one embodiment of the present invention, ln in the above formula is l4=4095 in the case of 12-bit (4096) gray scale of n=4.

The edge holding circuit 23 performs viewing angle correction (local edge holding processing) on the gradation image signal W1, and generates a gradation image signal W2 from the gradation image signal W1. When the front LCD panel 2 and the rear LCD panel 3 are seen from the front, there is no problem, but when viewed from the oblique direction, the positions of the display screen of the front LCD panel 2 and the display screen of the rear LCD panel 3 are offset by an angle due to the thickness of the lens, and thus a problem of ghost or chromatic aberration occurs. The present invention employs the edge holding circuit 23 for performing the viewing angle correction for the gray scale image. The gradation converter 24 converts the gradation image signal W2 into a gradation image signal W3 by performing an appropriate OETF (Optical-electric Transfer) on the gradation image signal W2 according to the characteristics of the rear LCD panel 3. Then, the gradation image signal W3 is supplied to the drive ICs of the rear LCD panel 3. The RGB image data generator 25 generates RGB image signals R2, G2, B2 from the RGB image signals R1, G1, B1 using the grayscale image signal W received from the grayscale converter 221 in the grayscale image data generator 22, the specific formula:

R2＝(Ln/W)×R1

G2＝(Ln/W)×G1

B2＝(Ln/W)×B1

where R2, G2, and B2 are signals controlling the luminance level of each pixel sub-pixel of the RGB image displayed on the front LCD panel 2. In the RGB image data generator 25, the lower the luminance of the grayscale image signal W, the higher the luminance level of the RGB image signal belonging to the subpixel of the pixel. When the dimming block is in the low luminance region, the RGB sub-pixels are less likely to cause black floating in the LCD due to the low luminance and high luminance level of the block, and thus a panel having good gradation characteristics can display the low luminance region. In the case of 12-bit (4096) gradation of n=4, ln in the above formula is l4=4095.

The second delay circuit 26 applies a second delay to the RGB image signals R2, G2, B2. The purpose of the second delay is to reduce the delay of the conversion process of the gradation image signal W1 in the level shifter 222 of the gradation image data generator 22 and the delay of the viewing angle correction process in the edge holding circuit 23. The RGB image signals supplied to the front LCD panel 2 by the second delay time can be made to match the timing with the gradation image signal W3 supplied to the rear LCD panel 3. The RGB image signals R3, G3, B3 are obtained after the second delay is applied. The RGB gray-scale converter 27 changes the received RGB image signals R3, G3 and B3 (OETF-suitable characteristics) into RGB image signals R4, G4, B4 according to the characteristics of the front LCD panel 2, and supplies the R4, G4 and B4 to the driving ICs of the front LCD panel 2. In one embodiment of the invention, the RGB gray-scale converter 27 is arranged after the second delay circuit 26. However, the second delay circuit 26 may be disposed after the RGB gray-scale converter 27 as long as timings of the RGB image signals R4, G4, B4 and the gray-scale image signal W3 can be matched eventually. That is, the RGB gray-scale converter 27 may perform OETF on the RGB image signals and then perform the second delay operation.

The third delay circuit 28 performs a third delay operation on the block luminance value Blum. The purpose of the third delay is to compensate for the delay caused by the processing of the RGB image signals and the processing of the grayscale image signals of the rear LCD panel 3. By the third delay, the RGB image signals R4, G4, B4 of the front LCD panel 2, the grayscale image signal W3 of the rear LCD panel 3, and the LED driving signal BD can be time-sequentially matched. And, the resulting block luminance value after the operation by performing the third delay is defined as a block luminance value blu 1. The LED driving signal generator 29 generates an LED driving signal BD that drives the LED backlight driving unit 4 according to the block brightness value blu 1 (brightness of each dimming block determined by the block brightness determining means 20) to adjust the brightness of the block. In one embodiment of the invention, the LEDs are dimmed by a PWM (pulse width modulation) method. Accordingly, the LED driving signal BD is a pulse signal of constant amplitude that changes the duty ratio according to the dimming brightness, and the signal BD is supplied to the LED driving unit of the LED backlight driving unit 4. In one embodiment of the present invention, the LEDs are dimmed by PWM, but the LEDs may also be dimmed by current control or the like. In this case, the LED dimming method performs dimming using the LED driving signal BD signal.

Further, in one embodiment of the present invention, the LED driving signal generator 29 is disposed after the third delay circuit 28, but eventually, the RGB image signals R4, G4, B4, the grayscale image signal W3, and the LED driving signal BD may adjust the above-described timing to the rear of the LED driving signal generator 29 through the third delay circuit 28. In addition to the delay circuits 21, 26 and 28 described above, some other delay circuits are used in the actual processing, and will not be described here.

As described above, in one embodiment of the present invention, the local dimming technique is applied to an image display device including the front LCD panel 2 for displaying RGB images and the rear LCD panel 3 for displaying gray-scale images. The RGB image is adjusted according to the gray level image generated by the RGB image, and the rear LCD panel 3 displays gray level according to the brightness of each dimming block, so as to generate a gray level signal picture for controlling the brightness level, thereby realizing mixing of a high brightness region and a low brightness region in one dimming block, preventing black floating phenomenon, and improving contrast ratio.

As shown in fig. 3, in the second embodiment of the present invention, the main difference from the first embodiment is in the process of signal processing. The implementation of this embodiment is mainly described with respect to the differences from the first embodiment, and the details of the same are not repeated. As shown in fig. 3, the block luminance determining device 34 converts the image data R, G and B into a gradation image signal for each pixel (each pixel), and performs local dimming on the luminance value of each dimming block (pixel block). The block luminance value determining device 34 includes a gradation converter 341, a maximum value extractor 342, and an applicable value determiner 201. The gradation converter 341 converts the RGB image signal into the gradation image signal W by using the maximum value of the three sub-pixel values (luminances) of the RGB image signal R, G, B as a representative value of the gradation image. The maximum value extractor 342 extracts the maximum value BLmax of the luminance in the dimming block from all the pixel values of the gray image signal W in the dimming block in the same manner as the embodiment of the maximum value extractor 200 in the first example, and a description thereof will not be repeated. The first embodiment extracts the maximum pixel value from R, G, B as BLmax for determining the block luminance blu, whereas the gradation converter 341 in the second embodiment of the present invention is provided inside the block luminance value determining means 34 for converting the RGB image signals R, G and B into the gradation image signal W and extracts the block maximum value BLmax using the gradation image signal W, thereby determining the block luminance value blu. Although in different ways, the end result is consistent.

The gray scale delay circuit 35 applies a fourth delay to the gray scale image signal W. The purpose of the fourth delay is to compensate for the delay in the conversion of the gradation converter 341 into the gradation image signal W in the block luminance value determination apparatus 34. By the fourth delay, the timings of the gradation image signal and the block luminance value blu in the level shifter 222 of the gradation image data generator 36 can be made to match and match with the R1, G1, B1 image data signals of the RGB image data generator 25. And, the image gradation signal after the fourth delay is applied is W0. The first delay circuit 21 delays the image data R, G, B by a first delay to obtain RGB image signals R1, G1, and B1. The image data generator 36 generates a gradation image signal W1 from the gradation image signal W0. The image data generator 36 includes a level shifter 222. As described in the block luminance value determination means 34 part, the gray image data generator does not require a gray converter at this time. The subsequent implementation steps are consistent with the implementation of the first embodiment and are not repeated here.

In the third embodiment of the present invention, as shown in fig. 4, the same parts as those of the second embodiment are not repeated. In the third embodiment, the configuration of the delay circuit of the signal processing unit is different from that of the second embodiment. The signal processing unit includes a block luminance value determining device 34, a gradation delay circuit 35 (fourth delay circuit), a gradation image data generator 36, an edge holding circuit 23, a gradation converter 24 and an RGB image data generator 25, a fifth delay circuit 49, an RGB gradation converter 27, a third delay circuit 28, an LED driving signal generator (backlight driving signal generator) 29. The image data R1, G1, B1 of the RGB image data generator 25 is obtained from the grayscale image signal W and the image data R, G, B by the following calculation method:

R1＝(Ln/W0)×R0

G1＝(Ln/W0)×G0

B1＝(Ln/W0)×B0

in the second embodiment, the RGB image data generator 25 receives the grayscale image W0 signal from the grayscale delay circuit 35 and generates R2, G2, B2 image data by R1, G1, B1. In the third embodiment of the present invention, however, the RGB image data generator 25 uses the gradation image signal W received from the gradation converter 341 of the block luminance value determination apparatus 34 and generates the image data R1, G1, B1 by the data R, G, B.

The fifth delay circuit 49 applies a fifth delay to the image data R1, G1, B1. The purpose of the fifth delay is to compensate for the delay in the conversion process of BLum, W1 and the viewing angle correction process of the edge holding circuit 23. The fifth delay will eventually ensure that the image data supplied to the RGB front LCD panel 2 and the grayscale image signal W3 supplied to the grayscale rear LCD panel 3 are synchronized. In one embodiment of the invention, the image data R3, G3, B3 are obtained after the fifth delay processing. In the third embodiment of the present invention, the processing sequence of the first delay circuit 21 and the RGB image data generator 25 is reversed to that of the second embodiment, and the first delay circuit 21 and the second delay circuit 26 are combined into one fifth delay circuit 49. Therefore, the delay time of the fifth delay circuit 49 of the third embodiment is the same as the total time of the delay time of the first delay circuit 21 and the delay time of the second delay circuit 26 of the second embodiment. The subsequent processing steps and manner are identical to those in the second embodiment.

In the third embodiment of the present invention, although the configuration of the delay circuit of the signal processing unit is different from that of the second embodiment, the object of displaying an HDR image can be achieved as in the first and second embodiments. In the image display apparatus, even if a high luminance area and a low luminance area are mixed in one dimming block, a maximum luminance of 10000 nits and a contrast of 2000000:1 can be achieved, and the occurrence of the black floating phenomenon can be prevented. Further, according to the third embodiment, comparing the delay circuit of the signal processing unit with the delay circuit of the second embodiment, the local dimming technique is applicable to the first and second embodiments, although the configuration is different.

While only a few embodiments of the present invention have been described, it should be noted that modifications could be made by those skilled in the art without departing from the principles of the present invention, which modifications are to be regarded as being within the scope of the invention.

Claims (10)

1. An LCD backlight control display system, comprising: a front LCD panel, a rear LCD panel, an LED backlight driving unit, a block luminance value determining device, an LED driving signal generator, a gray image data generator, an RGB image data generator, wherein:

the RGB image is input to the block luminance determining device, the gradation image data generator, the RGB image data generator:

in the block luminance value determining means, the luminance of each block is determined from the input RGB image signals R1, G1, and B1;

in the gray image data generator, a first gray image signal W is determined from the maximum brightness of the sub-pixels in the input RGB image signals R1, G1 and B1, and a second gray image signal W1 is generated from the first gray signal W;

in the RGB image data generator, the brightness level of each sub-pixel of the image signals R1, G1 and B1 is adjusted, and the RGB image signals R2, G2 and B2 are obtained after the adjustment, and the adjustment formula is:

R2＝(Ln/W)×R1

G2＝(Ln/W)×G1

B2＝(Ln/W)×B1

where Ln is the maximum brightness of the block of the LED backlight driving unit;

the RGB image data generator is connected to the front LCD panel, and outputs the adjusted RGB image signals R2, G2 and B2 thereto to display RGB images;

the gray image data generator is connected with the rear LCD panel and outputs a second gray image signal W1 to the rear LCD panel so as to display gray images; the block brightness value determining device, the LED driving signal generator and the LED backlight driving unit are sequentially connected, and the brightness of each block is transmitted to the LED driving signal generator, and an LED backlight driving signal is generated and transmitted to the LED backlight driving unit;

the front LCD panel, the rear LCD panel, and the LED backlight driving unit are sequentially arranged, and the LED backlight driving unit irradiates the front LCD panel, the rear LCD panel to adjust the brightness Blum of each block.

2. An LCD backlight control display system as claimed in claim 1, wherein the block luminance value determining means comprises a maximum value extractor for extracting the maximum luminance of the sub-pixels in each block of the input RGB image signals R1, G1 and B1, and an applicable value determiner; the applicable value determiner is configured to determine a luminance of the block based on the extracted maximum luminance.

3. The LCD backlight control display system of claim 1, wherein the gray image data generator comprises a gray converter and a level converter, wherein:

the gray-scale converter converts the input RGB image signals R1, G1, B1 into a first gray-scale image signal W for each pixel, taking the maximum brightness of the sub-pixel of each pixel as a representative value of the first gray-scale image signal W;

the level shifter converts the first gray scale image signal W into a second gray scale image signal W1:

W1＝W*Ln/Blum

where Ln is the maximum luminance of the block of the LED backlight driving unit and Blum is the block luminance value.

4. A LCD backlight control display system as claimed in claim 3, wherein the gray image data generator generates a second gray signal w1=ln/Blum.

5. An LCD backlight control display system as claimed in claim 1, wherein the lower the luminance of a block determined by the block luminance value determining means is, the higher the luminance level of a gray-scale image corresponding to each pixel of the block is.

6. An LCD backlight control display system according to claim 1, wherein the lower the luminance of the first gray scale image signal W, the higher the luminance level of the RGB image signals R1, G1 and B1 sub-pixels.

7. An LCD backlight control display system as claimed in claim 1, wherein the system further comprises an RGB gray-scale converter for correcting gray-scale of the RGB image signals R2, G2 and B2, the brightness levels of R2, G2 and B2 having been adjusted by the RGB image data generator to match the output characteristics of the front LCD panel.

8. An LCD backlight control display system as claimed in claim 1, characterized in that the RGB image generator is followed by a delay circuit for compensating the delay in the signal processing process, thereby ensuring the synchronization of the panel driving signals.

9. The LCD backlight control display system according to claim 1, further comprising an edge holding circuit for performing a viewing angle correction on the gray scale image signal W1 to generate a third gray scale image signal W2 from the second gray scale image signal W1 by:

where N represents the number of pixels, and f (i, j) represents the gray value of the gray image W1 at the pixel point (i, j).

10. The LCD backlight control display system as claimed in claim 10, further comprising a gray scale converter for photoelectrically converting the third gray scale image signal W2 according to the characteristics of the rear LCD panel to convert the third gray scale image signal W2 into the fourth gray scale image signal W3; the fourth grayscale image signal W3 is used to drive the rear LCD panel for grayscale image display.