Driving method of display module, driving system thereof, and display device

Abstract

The present disclosure provides a driving method of a display module, a driving system thereof, and a display device. The driving method of the display module includes a display panel driving process, and a backlight module driving process driven synchronously with the display panel driving process. The display panel driving process includes steps: receiving first color signals, and converting into second color signals to drive the display panel. The backlight module driving process includes steps: using the light source adjustment coefficient to adjust a first brightness value to obtain a second brightness value to driven first color light sources and/or second color light sources.

Description

CROSS REFERENCE OF RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No. CN201811510613.4, filed with National Intellectual Property Administration, PRC on Dec. 11, 2018 and entitled “DRIVING METHOD OF DISPLAY MODULE, DRIVING DEVICE THEREOF, AND DISPLAY DEVICE”, and claims priority to Chinese Patent Application No. CN201811511896.4, filed with National Intellectual Property Administration, PRC on Dec. 11, 2018 and entitled “DRIVING METHOD OF DISPLAY MODULE, DRIVING SYSTEM THEREOF, AND DISPLAY DEVICE”, which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a field of display panel technology, and in particular to a driving method of a display module, a driving system thereof, and a display device.

BACKGROUND

It should be understood that the statements herein merely provide background information related to the present disclosure and do not necessarily constitute relative art.

With the development and advancement of technology, liquid crystal displays have become mainstream products of displays because of their thin bodies, low power consumption and low radiation, and have been widely used. Conventional display apparatuses are mostly backlight display apparatuses, which includes a Liquid Crystal Display (LCD) panel and a backlight module. Operating principle of the LCD panel is that Liquid Crystal (LC) molecules are disposed between two glass substrates, where the two glass substrates are parallelly disposed, and a driver voltage is applied on the two glass substrates to control rotation directions of the LC molecules, so that light of the backlight module are refracted to generate images.

The present large-size liquid crystal display panel mostly adopts a Vertical Alignment (VA) liquid crystal technology or an In-Plane Switching (IPS) liquid crystal technology. Compared with the IPS liquid crystal technology, the VA liquid crystal technology has the advantages of high producing efficiency and low manufacturing cost, but there is an obvious optical property defect in the optical property. To be specific, some large-size display panels, especially a VA type liquid crystal drive, is rapidly saturated along with a voltage in large-visual-angle brightness, which makes a visual image quality contrast and a color cast deteriorate seriously compared with a front view image quality, that is to exist a large-visual-angle color cast.

SUMMARY

The present disclosure provides a driving method of a display module, a driving system thereof, and a display device to improve color deviation while improve the color saturation.

To achieve the above object, the present disclosure provides a driving method of a display module, includes a display panel driving process, and a backlight module driving process driven synchronously with the display panel driving process.

The display module includes a plurality of first color light sources and second color light sources. The first color light sources and the second color light sources are controlled independently.

The display panel driving process includes steps:

• receiving first color signals in an RGB (Red, Green, Blue) system corresponding to a display panel, and converting the first color signals into first color space signals in an HSV (Hue, Saturation, Value) system;
• adjusting a color saturation of the first color space signals by predetermined adjustment coefficients to obtain second color space signals in the HSV system, and converting the second color space signals into second color signals in the RGB system; and
• driving the display panel by the second color signals.

The backlight module driving process includes steps:

• receiving the first color signals in the RGB system corresponding to the display panel, obtaining the first color space signals in the HSV system and the second color space signals in the HSV system, and obtaining a light source adjustment coefficient according to the first color space signals and the second color space signals;
• adjusting a first brightness value corresponding to the first color light sources and/or the second color light sources by the light source adjustment coefficient to obtain a second brightness value; and
• driving the first color light sources and/or the second color light sources by the second brightness value.

The present disclosure further provides a driving system of a display module, including a display panel driving circuit, and a backlight module driving circuit driven synchronously with the display panel driving circuit.

The display module includes a plurality of first color light sources and second color light sources. The first color light sources and the second color light sources are controlled independently.

The display panel driving circuit includes a receiving circuit, a color saturation adjustment circuit, and a display panel driving circuit. The receiving circuit receives first color signals in an RGB system corresponding to a display panel and converts the first color signals into first color space signals in an HSV system. The color saturation adjustment circuit adjusting a color saturation of the first color space signals by predetermined adjustment coefficients to obtain second color space signals in the HSV system and converting the second color space signals into second color signals in the RGB system. The display panel driving circuit driving the display panel by the second color signals.

The backlight module driving circuit includes a light source adjustment calculation circuit, a light source adjustment circuit, and a backlight module driving circuit. The light source adjustment calculation circuit receives the first color signals in the RGB system corresponding to the display panel, obtains the first color space signals in the HSV system and the second color space signals in the HSV system, and obtains a light source adjustment coefficient according to the first color space signals and the second color space signals. The light source adjustment circuit adjusts a first brightness value corresponding to the first color light source and/or the second color light source by the light source adjustment coefficient to obtain a second brightness value. The backlight module driving circuit drives the first color light sources and/or the second color light sources by the second brightness value.

The present disclosure further provides a display device including the driving system of the display module. The driving system of the display module includes a display panel driving circuit, and a backlight module driving circuit driven synchronously with the display panel driving circuit.

The display module includes a plurality of first color light sources and second color light sources. The first color light sources and the second color light sources are controlled independently.

The display panel driving circuit includes a receiving circuit, a color saturation adjustment circuit, and a display panel driving circuit. The receiving circuit receives first color signals in an RGB system corresponding to a display panel and converts the first color signals into first color space signals in an HSV system. The color saturation adjustment circuit adjusting a color saturation of the first color space signals by predetermined adjustment coefficients to obtain second color space signals in the HSV system and converting the second color space signals into second color signals in the RGB system. The display panel driving circuit driving the display panel by the second color signals.

The backlight module driving circuit includes a light source adjustment calculation circuit, a light source adjustment circuit, and a backlight module driving circuit. The light source adjustment calculation circuit receives the first color signals in the RGB system corresponding to the display panel, obtains the first color space signals in the HSV system and the second color space signals in the HSV system, and obtains a light source adjustment coefficient according to the first color space signals and the second color space signals. The light source adjustment circuit adjusts a first brightness value corresponding to the first color light source and/or the second color light source by the light source adjustment coefficient to obtain a second brightness value. The backlight module driving circuit drives the first color light sources and/or the second color light sources, by the second brightness value.

In the present disclosure, in a technique that is known but not disclosed by the applicant, since in the RGB system, a high color saturation value lead to a severe color deviation. In order to solve the problem, the first color signals in the RGB system are converted into the first color space signals in the HSV system. And then, the first color space signals are adjusted to obtain the second color signals with improved color deviation. Basing on this, the second brightness value is configured to adjust an intensity of the light sources while adjusting the color saturation, thereby returning the color saturation signal that color saturation is damaged from an unsaturated color point to a saturated hue, which reduces the color deviation, especially reduces a wide viewing angle color deviation. And at the same time, a good color saturation is maintained and a good color performance of solid colors is achieved.

BRIEF DESCRIPTION OF DRAWINGS

The drawings are included to provide a further understanding of embodiments of the present disclosure, which form portions of the specification and are used to illustrate implementation manners of the present disclosure and are intended to illustrate operating principles of the present disclosure together with the description. Apparently, the drawings in the following description are merely some of the embodiments of the present disclosure, and those skilled in the art are able to obtain other drawings according to the drawings without contributing any inventive labor. In the drawing:

FIG. 1 is a schematic diagram of color deviation variations of a wide viewing angle and a front viewing angle of various representative color systems of a liquid crystal display.

FIG. 2 is a first schematic diagram of dividing an original pixel into main pixels/sub-pixels in an exemplary scheme.

FIG. 3 is a second schematic diagram of dividing an original pixel into main pixels/sub-pixels in an exemplary scheme.

FIG. 4 is a flowchart of a display panel driving process according to one embodiment of the present disclosure.

FIG. 5 is a flowchart of a backlight module driving process according to one embodiment of the present disclosure.

FIG. 6 is a schematic diagram of a direct-lit display module of the present disclosure.

FIG. 7 is a schematic diagram of a correlation function of a second predetermined adjustment coefficient H2 in one embodiment of the present disclosure.

FIG. 8 is a schematic diagram of variations of a current color saturation signal and the second color saturation signal according to one embodiment of the present disclosure.

FIG. 9 is a graph showing aberration variations of the current color saturation signal and the second color saturation signal according to one embodiment of the present disclosure.

FIG. 10 is a schematic diagram of aberration variations of the current color saturation signal and the second color saturation signal according to one embodiment of the present disclosure.

FIG. 11 is a schematic diagram of a driving system of a display panel according to one embodiment of the present disclosure.

FIG. 12 is a schematic diagram of a driving circuit of a display panel according to one embodiment of the present disclosure.

FIG. 13 is a schematic diagram of a driving circuit of a backlight module according to one embodiment of the present disclosure, and

FIG. 14 is a schematic diagram of a display device according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

Specific structure and function details disclosed herein are only representative and are used for the purpose of describing exemplary embodiments of the present disclosure. However, the present disclosure may be achieved in many alternative forms and shall not be interpreted to be only limited to the embodiments described herein.

FIG. 1 is a schematic diagram of the present disclosure adopting main pixels and sub-pixels to improve color deviation.

In a large-size liquid crystal display panel, especially in a Vertical Alignment (VA) type liquid crystal display panel, voltage rapidly saturates a corresponding wide viewing angle brightness, resulting in a sharp contrast and image quality color deviation from a wide viewing angle compared to the image quality from a front view.

FIG. 1 is a schematic diagram of color deviation variations of a wide viewing angle and a front viewing angle of various representative color systems of a liquid crystal display. As shown in FIG. 1, the ordinate indicates a degree of a color deviation, and it is obvious that the color deviation of R, G, and B hue is more severe than that of other colors.

An exemplary solution is to divide the RGB (Red, Green, Blue) sub-pixels into main pixels/sub-pixels, so that an overall brightness viewed from wide viewing angle approaches the brightness viewed from a front viewing angle along with a variation of the voltage.

FIG. 2 is a first comparison diagram of distinguishing between original pixels and distinguishing main pixels and sub-pixels. FIG. 3 is a second comparison diagram of distinguishing between original pixels and distinguishing main pixels and sub-pixels. As shown in FIG. 2 and FIG. 3, the x coordinate, the y coordinate, and the z coordinate represent three directions of three-dimensional space respectively. The θA represents a pretilt angle of the main pixels at a large voltage, and θB represents a pretilt angle of the sub-pixels at a small voltage. The abscissa in FIG. 3 is a gray-scale signal, and the ordinate in FIG. 3 is a luminance signal. At a wide viewing angle, the brightness is rapidly saturated with the signal, leading to a large view color deviation (FIG. 3, the arc segment on the left side). Dividing the pixels into main pixels and the sub-pixels is able to improve the phenomenon of color deviation to some extent.

To be specific, the original signals are divided into main pixels and sub-pixels with large voltage and small voltage. The large voltage and the small voltage on the front view are configured to make original front signals to change along with a brightness variation. Part A of FIG. 3 shows that the brightness in the large voltage viewing from side changes along with the grayscales. Part B of FIG. 3 shows that the brightness in the small voltage viewing from side changes along with the grayscale, in this way, the brightness of the side view synthesis changes with the grayscale as the arc in the left side, which is closer to the line in the right side, which indicates the brightness viewing from the front viewing angle along with the grayscale. Thus, the brightness viewing from the side view approaches the brightness viewing from the front view, and the color deviation caused by viewing from different angles is improved.

The defect is solved by applying different driving voltages on the main pixels and sub-pixels in space. However, it is need to re-design metal wires or Thin Film Transistor (TFT) elements to drive the sub-pixels, which sacrifices a light-transmissive opening region, affects a panel penetration rate, and directly improves costs of the backlight.

Thus, the present disclosure provides a solution based on an improvement of different technical concepts, of which is as follows.

The present disclosure will be further described below in conjunction with the accompanying drawings and embodiments.

FIG. 4 is a flowchart of a display panel driving process according to one embodiment of the present disclosure. FIG. 5 is a flowchart of a backlight module driving process according to one embodiment of the present disclosure. As shown in FIGS. 4 and 5, the present disclosure provides a driving method of a display module, includes a display panel driving process, and a backlight module driving process driven synchronously with the display panel driving process. The display module includes a plurality of first color light sources and second color light sources. The first color light sources and the second color light sources are controlled independently.

The display panel driving process includes steps:

• S11: receiving first color signals in an RGB system corresponding to a display panel, and converting the first color signals into first color space signals in an HSV system;
• S12: adjusting a color saturation of the first color space signals by predetermined adjustment coefficients to obtain second color space signals in the HSV system, and converting the second color space signals into second color signals in the RGB system; and
• S13: driving the display panel by the second color signals.

The backlight module driving process includes steps:

• S21: receiving the first color signals in the RGB system corresponding to the display panel, obtaining the first color space signals in the HSV system and the second color space signals in the HSV system, and obtaining a light source adjustment coefficient according to the first color space signals and the second color space signals;
• S22: adjusting a first brightness value corresponding to the first color light sources and/or the second color light sources by the light source adjustment coefficient to obtain a second brightness value; and
• S23: driving the first color light sources and/or the second color light sources by the second brightness value.

The driving system on which the driving method is applied is disposed at a front end of the display panel, specially disposed in a timing control chip of the display panel. The timing control chip further stores parameters such as the predetermined adjustment coefficient look up table related to the performance of the display panel corresponding to the driving system.

In the present disclosure, in a technique that is known but not disclosed by the applicant, since in the RGB system, a high color saturation value lead to a severe color deviation. In order to solve the problem, the first color signals in the RGB system are converted into the first color space signals in the HSV system. And then, the first color space signals are adjusted to obtain the second color signals with improved color deviation. Basing on this, the second brightness value is configured to adjust an intensity of the light sources while adjusting the color saturation, thereby returning the color saturation signal that color saturation is damaged from an unsaturated color point to a saturated hue, which reduces the color deviation, especially reduces a wide viewing angle color deviation. And at the same time, a good color saturation is maintained and a good color performance of solid colors is achieved.

The display panel driving process and the backlight module driving process are separately performed but are driven synchronously. For example, in the backlight module driving process, the first color space signals and the second color space signals are obtained by calculating, which is separate from the display panel driving process. Of course, the first color space signals and the second color space signals are able to be obtained from the display panel driving process, and then transmitted to the backlight module (corresponding signal processing circuit) for recalculation to obtain the light source adjustment coefficient, as long as driving the display panel and backlight module synchronously ultimately.

FIG. 6 is a schematic diagram of a direct-lit display module of the present disclosure. As shown in FIG. 6, and further combined with FIGS. 4 and 5, in one or more embodiments, the display module is a direct-lit backlight display module. The direct-lit backlight display module includes a plurality of backlight partitions. Each of the backlight partitions includes the plurality of the first color light sources and the second color light sources. Each of the backlight partitions further includes a plurality of third color light sources, and the third color light sources are controlled independently.

The backlight partitions include three light sources controlled independently as shown in FIG. 6 and may adapt to other structures.

Of course, other types of display modules are also possible, as long as they are applicable.

In one or more embodiments, the display panel is the direct-lit display panel, which is able to compensate for the loss of color saturation by adjusting the intensity of the light sources. To be specific, each of the backlight partitions includes the plurality of the first color light sources controlled independently, the second color light sources controlled independently, and the third color light sources controlled independently. Thus, since the color saturation value S=1−min/max, where min and max are related to the stimulus value signal in the RGB system, According to the calculation, it is determined that increasing the intensity of the light source of one or several light sources is helpful for the complementary of the color saturation, and then correspondingly adjusting, thereby improving the color deviation, and maintaining good solid color performance of colors.

In one or more embodiments, the step of obtaining the light source adjustment coefficient according to the first color space signals and the second color space signals includes steps:

• obtaining the first color space signals and the second color space signals of all pixels in current backlight partitions corresponding to a current frame, calculating a first average color saturation signal corresponding to the first color space signals and a second average color saturation signal corresponding to the second color space signals respectively; and
• obtaining the light source adjustment coefficient by calculating the first average color saturation signal and the second average color saturation signal.

In one or more embodiments, the intensity of the light sources is adjusted in units of one backlight partition to obtain the first color space signals and the second color space signals. First, comparing a difference between the color saturation of the first color signals and the second color signals before a color saturation adjustment operation and the color saturation of the first color signals and the second color signals after the color saturation adjustment operation by measuring the first average color saturation signal Sn_ave corresponding to the first color space signals, and the second average color saturation signal S′n_ave corresponding to the second color space signals. Then, based on the difference, the light source adjustment coefficient is calculated, so that the backlight partitions of the display panel improves the color deviation, and the backlight partitions are regarded as one, and each of the backlight partitions separately compensates the color saturation to maintain a good solid color performance of colors.

In one or more embodiment, the step of calculating the light source adjustment coefficient includes steps:

• calculating a first average color saturation signal corresponding to the first color space signals by using a formula Sn_ave=Average(Sn_1,1, Sn_1,2, . . . , Sn_i,j);
• calculating a second average color saturation signal corresponding to the second color space signals by using a formulaS′n_ave=Average(S′n_1,1,S′n_1,2, . . . ,S′n_i,j); and
• obtaining the light source adjustment coefficient by calculating the first average color saturation signal Sn_ave and the second average color saturation signal S′n_ave.

In one or more embodiments, all the first color space signals and the second color space signals are obtained in units of one backlight partition, and the color saturation signals are captured, and all the color saturation signals are averaged to calculate the light source adjustment coefficient, such that the color deviation of the backlight partitions of the display panel improves, and the backlight partitions is integrated as one. And each of the backlight partitions separately compensates the color saturation to maintain a good solid color performance of colors.

The step of converting the first color signals into first color space signals in the HSV system includes steps:

• obtaining first color signals Rn_i,j, Gn_i,j, Bn_i,j, and converting each group of RGB three primary color sub-pixel grayscale signals into three primary color normalized luminance signals r, g, b; and obtain the first normalized luminance signals rn_i,j, gn_i,j, bn_i,j after completing the conversion; and
• converting the first color signals into the first color space signals according to the the first normalized luminance signals, where Sni,j=1−minni,j/maxni,j.

The step of lowering the color saturation values of the current color saturation signals by the predetermined adjustment coefficients, completing the adjustment process of the current color saturation signals, and obtaining the second color space signals in the HSV system includes steps:

• keeping mini,j unchanged while adjusting mini,j by the predetermined adjustment coefficients; and
• completing an adjustment of the color saturation signals to obtained the second color space signals in the HSV system; where S′=1−mini,j*H/maxi,j; and mini,j=min (rn_i,j, gn_i,j, bn_i,j), and maxi,j=max(rn_i,j, gn_i,j, bn_i,j).min n_i,j=min(r,g,b); and max n_i,j=max(r,g,b);r=(R/255){circumflex over ( )}γr,g=(G/255){circumflex over ( )}γg,b=(B/255){circumflex over ( )}γb, and
• γr, γg, γb are gamma signals of the first color signals.

The R, G, B refer to the RGB three primary color grayscale digital signals corresponding to the first color signals. In one or more embodiments, corresponding to the first color space signals corresponding to the first color signals and the second color space signals corresponding to the second color signals, average values of all color saturation signals in the backlight partitions are respectively calculated to obtain the first average color saturation signal and the second average color saturation signal. And the display difference of the backlight partitions between the color saturation before the adjustment and the color saturation after the adjustment (in order to improve the color deviation) is reflected by the first average color saturation signal and the second average color saturation signal, thus, the light source adjustment coefficients are calculated, the calculation step is simple. Based on the overall display effect, the production efficiency is improved, and overall uniformity of the color saturation of the backlight partitions is maintained, and the local color saturation is prevented from being too high or too low, which is beneficial for improving the display.

In one or more embodiments, the step of obtaining the light source adjustment coefficient by calculating the first average color saturation signal and the second average color saturation signal includes steps:

• calculating the first average color saturation signal by using a formula Sn_ave=1−minn_ave/maxn_ave;
• calculating the second average color saturation signal by using a formula S′n_ave=1−min′n_ave/max′n_ave; and
• obtaining a third average color saturation signal S″n_ave according to the light source adjustment coefficient and the second average color saturation signal.

The light source adjustment coefficient y satisfies following formulas:S″n_ave=Sn_ave;1−min n_ave/max n_ave=1−min′n_ave/(max′n_ave*y); andy=(S′n_ave−1)/(Sn_ave−1).

Where maxn_ave is a maximum average signal among a red sub-pixel average signal, a green sub-pixel average signal, and a blue sub-pixel average signal of the first color signals of all pixels in current backlight partitions corresponding to a current frame. And minn_ave is a minimum average signal among the red sub-pixel average signal, the green sub-pixel average signal, and the blue sub-pixel average signal of the first color signals of all pixels in the current backlight partitions corresponding to the current frame.

Where maxn_ave is also a maximum average signal of the second color signals among a red sub-pixel average signal, a green sub-pixel average signal, and a blue sub-pixel average signal of the second color signals of all pixels in the current backlight partitions corresponding to the current frame. And min′n_ave is a minimum average signal among the red sub-pixel average signal, the green sub-pixel average signal, and the blue sub-pixel average signal of the second color signals of all pixels in the current backlight partitions corresponding to the current frame.

In one or more embodiments, the maximum average signal of the second color signals is same as the maximum average signal of the first color signals. Since in the color saturation process, maxij of each pixel is unchanged, and mini,j of each pixel is adjust, thus the external maxn_ave is unchanged. There is no need to calculate minn_ave, maxn_ave, and min′n_ave of the formulas Sn_ave=1−minn_ave/maxn_ave, and S′n_ave=1−min′n_ave/maxn_ave, but they can be estimated by the color saturation signal. The calculated values are configured to assist the calculation, and finally the light source adjustment coefficient is obtained by the formula y=(S′n_ave−1)/(Sn_ave−1). The light source adjustment coefficient is obtained by the formula Sn_ave=Average(Sn_1,1, Sn_1,2, . . . , Sn_i,j), and the formula S′n_ave=Average(S′n_1,1, S′n_1,2, . . . , S′ n_i,j). And the light source adjustment coefficient is calculated based on the overall color saturation difference of the backlight partitions, which ensures that the color saturation of the backlight partition is well compensated.

In one or more embodiments, the step of obtaining the predetermined adjustment coefficients corresponding to the current color saturation signals includes steps: obtaining the color saturation signals of the first color spaces signals; the predetermined adjustment coefficients are calculated by calculating the color saturation signals according to a predetermined calculation formula or by looking up in a predetermined adjustment coefficient look up table.

In one or more embodiments, in the RGB system, the higher the color saturation of the signals, the more severe the color deviation is. Thus, the color deviation of some of the color saturation values is severe, and color deviation of some of the color saturation values is not obvious and is in an acceptable range, in one or more embodiments, the current color saturation signals are obtained, and the predetermined adjustment coefficients corresponding to the current color saturation signals are obtained, and the color saturation of the color saturation signals is adjusted, thus, the color saturation values is controlled in areas where the color deviation is less severe. In addition, the embodiment is not based on the sacrifice of the light-transmissive opening region, thus, a light transmittance is prevented from being lowered, and production costs of the display panel is lowered.

The adjustment coefficient look up table is a look up table directly recorded with predetermined adjustment coefficients, or is a look up table recording a predetermined calculation formula.

The second color space signals and the first color space signals conform to a following formula:S′=a*S4+b*S3+c*S2+d*S+e;

S is the current color saturation signals corresponding to the first color space signals, and S′ is the color saturation signal corresponding to the second color space signals. The a, b, c, d, e are constants, and the a, b, c, d, e are obtained by looking up in the predetermined formula coefficient look up table according to the different color saturation values and the different hue intervals.

In one or more embodiments, the predetermined adjustment coefficients are calculated according to the predetermined calculation formulas, and although the calculation formulas are different, it is generally satisfied with the fourth-order polynomial. The a, b, c, d, e are constants, and the a, b, c, d, e are obtained by looking up in the predetermined formula coefficient look up table according to the different color saturation values and the different hue intervals. Of course, other calculation formulas are also applicable. For example, when the color saturation value S satisfies certain conditions, the predetermined adjustment coefficient is equal to the square root of S. When the color saturation value S satisfies another condition, the predetermined adjustment coefficient is equal to the cubic root of S.

The step of adjusting the color saturation of the first color space signals by the predetermined adjustment coefficients to obtain the second color space signals in the HSV system includes steps:

• obtaining current color saturation signals of the first color space signals, detecting whether the current color saturation signals satisfy a predetermined color saturation threshold, and detecting whether the current color saturation signals are in an adjusted hue interval, and if yes, obtaining corresponding predetermined adjustment coefficients according to the corresponding color saturation values and corresponding hue intervals based on the color saturation signals; and
• adjusting the current color saturation signals to obtain the second color space signals in the HSV system by the predetermined adjustment coefficients.

The color saturation threshold is 0.5, and if the color saturation values of the current color saturation signals are more than 0.5, the color saturation values of the current color saturation signals satisfy the color saturation threshold. Or the color saturation threshold is an interval, e.g. 0.5-1, that is, the color saturation threshold is more than 0.5 and less than 1. When the color saturation threshold is more than 0.5 and less than 1, the color saturation is adjusted. When the color saturation threshold is 0.5 or 1, there is no need to adjust the color saturation.

In one or more embodiments, only part of the color saturation signals are adjusted, and the part of the color saturation signals not only need to satisfy the color saturation threshold, but also need to satisfy the hue interval. Since correspondences between color saturation values of different hue intervals and different color deviations are different. The greater the color saturation values, the more severe the color deviation is. In addition, the closer to the dominant hue, the more severe the color deviation is. For example, in a same color saturation value, the color deviation in the hue interval corresponding to a blue dominant hue of a 240-degree hue is far more than an unadjusted hue interval of a 300-degree hue. At this time, even the color saturation signals of a 300-degree hue satisfies the color saturation threshold, a degree of the color deviation is small and does not need to be improved. Similarly, if the color saturation values are high, but the hue interval is appropriate, the color deviation of the corresponding color saturation signals may not be particularly serious and does not need to be adjusted. Thus, only the color saturation signals satisfy both of the color saturation threshold and the hue interval are needed to be adjusted. For example, to reduce the color saturation values is able to improve the color deviation, and to avoid unnecessary processing for signals that does not need the color deviation adjustment (such as lowering the color saturation values), thereby improving the display of the display panel.

The color saturation signals are split into at least a first hue interval, a second hue interval, and a third hue interval according to different hues. In the step of obtaining the predetermined adjustment coefficients corresponding to the current color saturation signals:

• when corresponding to a same hue, greater the color saturation values of the current color saturation signals, greater an adjustment amplitude of the adjustment process is.

In one or more embodiments, in the same hue interval, especially in the same hue, the higher the color saturation values of the color saturation signals, the more severe the corresponding color deviation is. Therefore, the adjustment amplitude for the signals with a high color saturation value is large, and the adjustment amplitude for the signals with a low color saturation value is small. In generally, the color saturation values of the color saturation signals are lowered, thus, the color deviation caused by the high color saturation is avoided, the color deviation caused by excessive color saturation difference is avoided, and a good effect of the improvement of the color deviation is achieved. Of course, it is possible to increase the value of the color saturation signals with a low color saturation value, which makes the color saturation signals more uniform and also improves the color deviation to some extent.

In one or more embodiments, the color saturation signals are split into a red hue interval, a green hue interval, a blue hue interval, and an unadjusted hue interval according to different hue intervals.

A hue value ranges from 0-360, corresponding to 0-360 degrees.

The hue value of a hue interval satisfying a following formula is the red hue interval: 0≤Hue<40, or 320<Hue≤360.

The hue value of the hue interval satisfying a following formula is the green hue interval: 80<Hue<160.

The hue value of the hue interval satisfying a following formula is the blue hue interval: 40≤Hue≤80, or 160≤Hue≤200.

The hue value of the hue interval satisfying the following formula is the unadjusted hue interval: 40≤Hue≤80, or 160≤Hue≤200, or 280≤Hue≤320.

In one or more embodiments, in view of the RGB system, 0 degree is defined as a red hue, 120 degrees is defined as a green hue, and 240 degrees is defined as a blue hue. Under the premise of the same color saturation value, the closer to the red hue, the green hue, and the blue hue, the more severe the color deviation is. The farther away from the red hue, the green hue, and the blue hue, the lighter the color deviation of the color saturation signals is, and even the color saturation signals conform to the color deviation standard and does not need to be adjusted. In one or more embodiments, the hues close to the green hue is defined as the green hue interval, the hues close to the blue hue is defined as the blue hue interval, the hues close to the red hue is defined as a red hue interval, and the hues away from the red hue, the green hue, and the blue hue is defined as the unadjusted interval. Thus, corresponding to the same color saturation value, the predetermined adjustment coefficients of the blue hue interval having the most severe color deviation are set to be large, the predetermined adjustment coefficients of the green hue interval having the lightest color deviation are set to be small, and for the unadjusted hue interval where there is almost no color deviation, no adjustment is made, or the corresponding predetermined adjustment coefficients is set to be 1. In this way, the color deviation is improving, the decrease of the color saturation values is avoided, which is beneficial to improve the display of the display panel.

In addition, the adjustment amplitude herein refers to lower the amplitude of the color saturation signals. The larger the color saturation values, the corresponding predetermined adjustment coefficient may be smaller or larger according to different calculation formulas. However, an effect of the adjustment amplitude is constant. For example, if the predetermined adjustment coefficient is the coefficient of the overall color saturation signals, e.g. S′=S*H (where S is the current color saturation signals and S′ is the second color saturation signals, H is the predetermined adjustment coefficients), the greater the adjustment amplitude of lowering the value, the smaller the value of the predetermined adjustment coefficients. If the predetermined adjustment coefficient is the coefficient of one of the parameters of the color saturation signals, e.g. S′=1−min*H/max (where S is the current color saturation signal, S′ is the second color saturation signal, H is the predetermined adjustment coefficient, and min and max are the minimum and maximum values of the normalized luminance signals r, g, b when the RGB three primary color signals are converted into signals in the HSV system), the greater the adjustment amplitude of lowering the value, the greater the corresponding coefficient is. The larger the predetermined adjustment coefficient at this time, the larger the corresponding reduction adjustment amplitude is.

To be specific, the first hue interval, the second hue interval, and the third hue interval are defined as the red hue interval, the green hue interval, and the blue hue interval respectively.

In the current color saturation signals having the same color saturation value, an adjustment amplitude of the predetermined color adjustment signals corresponding to the blue hue interval to the current color saturation signals is greater than an adjustment amplitude of the predetermined color adjustment signals corresponding to the red hue interval to the current color saturation signals. The adjustment amplitude of the predetermined color adjustment signals corresponding to the red hue interval to the current color saturation signals is greater than an adjustment amplitude of the predetermined color adjustment signals corresponding to the green hue interval to the current color saturation signals.

In one or more embodiments, the degrees of color deviation of the color saturation signals in different hue intervals are different. In the same color saturation value, the color deviation of some of the hue intervals is severe, and the color deviation of some hue intervals is light. In RGB system, the color deviation of color saturation signals in the blue hue interval is the most severe, and the color deviation of color saturation signals in the green hue interval is lighter. In this scheme, taking S′=S*H as an example, the predetermined adjustment coefficients corresponding to the blue hue interval are smaller than the predetermined adjustment coefficients corresponding to the red hue interval, and the predetermined adjustment coefficients corresponding to the red hue interval are smaller than the predetermined adjustment coefficients corresponding to the green hue interval. The smaller the predetermined adjustment coefficients, the larger the adjustment amplitude is. Correspondingly, taking S′=1−min*H/max as an example, the predetermined adjustment coefficients corresponding to the blue hue interval are the largest among the hue intervals and the adjustment amplitude is the largest, and the predetermined adjustment coefficients corresponding to the green hue interval are the smallest among the hue intervals and the adjustment amplitude is the smallest. Thus, in the same color saturation value, the color saturation signals in the blue hue interval have the larger reduction adjustment amplitude, and the color saturation signals in the green hue interval have the smaller reduction adjustment amplitude, which not only reduce the color deviation caused by the large color saturation values, but also make the color saturation of the color saturation signals more uniform, and also help to improve color deviation to some extent. Thus, the good improvement in color deviation is achieved.

In one or more embodiments, the step of adjusting the color saturation of the first color space signals by the predetermined adjustment coefficients to obtain the second color space signals in the HSV system, and converting the second color space signals into the second color signals in the RGB system; and driving the display panel by the second color signals includes steps:

• obtaining the third color saturation signals S″ by calculating the current color saturation signals S and the second color saturation signals S′;
• completing two times of color saturation adjustment; and obtaining the second color space signals in the HSV system based on the third color saturation signals; and
• converting the second color space signals into the second color signals in the RGB system to drive the display panel.

FIG. 7 is a schematic diagram of a correlation function of a second predetermined adjustment coefficient H2 in one or more embodiments of the present disclosure. As shown in FIG. 7, and combined with FIGS. 4 to 6, the third color saturation signals satisfy a following formula:S″=S−(S−S?)*H2.The second predetermined adjustment coefficient H2 satisfies a following formula:H2=2*ABS(sin((Hue/360*3−½)*π)−1.

In one or more embodiments, the second predetermined adjustment coefficients H2 is an adjustment coefficient configured to adjust the second color saturation signals into the third color saturation signals. In the RGB system, 0 degree is defined as a red solid color hue, 120 degrees is defined as a green solid color hue, and 240 degrees is defined as a blue solid color hue. In the same color saturation value, the closer to the solid color hue, the more severe the color deviation is. Base on the second predetermined adjustment coefficients H2, the color saturation signals closer to the solid color hue obtains a larger secondary adjustment, and the color saturation signals away from the solid color hue obtains a small amplitude secondary adjustment. In this way, the color saturation signals near the solid color hue achieves a good effect of improving the color deviation, while for the color saturation signals away from the solid color hue, the overall color saturation damage caused by the improvement of the color deviation is lowered. Thus, the balance of the color deviation and the color saturation is achieved, which is beneficial to improve the display of the display panel.

In the color saturation adjustment stage:

FIG. 8 is a schematic diagram of variations of a current color saturation signal and a second color saturation signal according to one embodiment of the present disclosure FIG. 9 is a graph showing an aberration variation of the current color saturation signal and the second color saturation signal according to one embodiment of the present disclosure. FIG. 10 is a schematic diagram of aberration variations of the current color saturation signal and the second color saturation signal according to one embodiment of the present disclosure.

The graph of the aberration variation shown in FIG. 9 may be in the case of a front viewing angle, of course, it can also be in the case of a side viewing angle. The dotted line in FIG. 10 is the aberration variation corresponding to the current color saturation signal in various color systems, and the solid line is the aberration variation corresponding to the second color saturation signal in various color systems.

To be specific, the input signals of the display is RGB three primary color signals. If the display is driven by 8-bit color resolution, the tone of the RGB three primary color input signals are decomposed into 0, 1, 2.255 grayscale drive signals. In the present disclosure, the RGB three primary color signals are converted into HSV color space signals, and the color saturation is adjusted according to different hues and different color saturation values in the color space of the HSV to achieve the effect of the improvement of the color deviation.

Referring to FIG. 1, it shows the color deviation variations of a wide viewing angle and a front view of various representative color systems of the liquid crystal display. It is obvious that the color deviation of R, G, and B hues is more severe than that of other colors. Therefore, solving the color deviation of the r, g, and b hues is able to greatly improve the overall color deviation viewing from the wide viewing angle.

The calculation method of converting the color signals in the RGB system or the RGB three primary color signals into HSV signals is as follows: the input signals of the RGB three primary colors are 8-bit grayscale digital signals of 0, 1, 255, and each grayscale digital signal corresponding to the luminance normalized signal of the 255 input signals (the 255 grayscale is the maximum luminance) is r, g, b, respectively; where r=(R/255){circumflex over ( )}γγ, g=(G/255){circumflex over ( )}γγ, b=(B/255){circumflex over ( )}γb, where γr, γg, γb are gamma signals, and grayscale digital signals is converted into an exponential parameter of the luminance signal. H is a hue signal, and r, g, b normalized luminance signals are converted into a hue h and a saturation s signal. Among them, H is a color representation, which is represented by different degrees of hues from 0 degree to 360 degrees, where 0 degree is defined as red, 120 degrees is green, and 240 degrees is blue. Where R is a red grayscale digital signal, G is a green grayscale digital signal, B is a blue grayscale digital signal. Where min is the minimum of r, g, b, and max is the maximum of r, g, b.

The conversion relationship between r, g, b normalized luminance signals and hue h, and the saturation signals conform to a following formula:

$h=\{\begin{array}{cc}0°& \mathrm{if}\max =\min \\ 60°\times \frac{g-b}{\max -\min }+0°& \mathrm{if}\max =r\mathrm{and}g\ge b\\ 60°\times \frac{g-b}{\max -\min }+360°& \mathrm{if}\max =r\mathrm{and}g<b\\ 60°\times \frac{b-r}{\max -\min }+120°& \mathrm{if}\max =g\\ 60°\times \frac{r-g}{\max -\min }+240°& \mathrm{if}\max =b\end{array}s=\{\begin{array}{cc}0°& \mathrm{if}\max =0\\ 1-\frac{\min }{\max },& \mathrm{otherwise}\end{array}$

In summary, when the hue is close to the R, G, B solid color hue, the color deviation deterioration of the wide viewing angle is more obvious. And when the hue is close to the R, G, B solid color hue, the greater the color saturation s, the more obvious the color deviation is. The color saturation s of the R, G, B solid color hues are lowered to improve the color viewed from the wide viewing angle comparing to the color viewed from the front view angel, that is, the closer to the solid color hue, the greater the adjustment amplitude is. In addition, after completing the color saturation adjustment, a detection step is added. For example, converting the color saturation signals into the Commission Internationale De l'Eclairage Lu'v'color space signals, where L is a luminance coordinate and u′ and v′ are chroma coordinates. In order to improve the color deviation, the color saturation adjustment is to lower the color saturation values of the current color saturation signals, but if it is to reduce a loss of the color saturation, the solid color changes, that is, the current color saturation signals S are changed to the second color saturation signals S′. And the solid color change or the aberration Δv should satisfy: Δuv=√{square root over (((u_1−u_2){circumflex over ( )}2+(v_1−v_2){circumflex over ( )}2)}≤0.02. Where u_1 and v_1 are the chroma coordinates of the current color saturation signal, and u_2 and v_2 are the chroma coordinates of the second color saturation signals which are the color saturation signal after the color saturation adjustment.

FIG. 11 is a schematic diagram of a driving system of a display panel according to one embodiment of the present disclosure. FIG. 12 is a schematic diagram of a driving circuit of a display panel according to one embodiment of the present disclosure. FIG. 13 is a schematic diagram of a driving circuit of a backlight module according to one embodiment of the present disclosure. As shown in FIGS. 11 to 13, and combined with FIGS. 1 to 10, the present disclosure further provides a driving system of a display module 100, on which the above driving method is applied. The driving system includes a display panel driving circuit 110, and a backlight module driving circuit 120 driven synchronously with the display panel driving circuit 110.

The display module includes a plurality of first color light sources 130 and second color light sources 140. The first color light sources 130 and the second color light sources 140 are controlled independently.

The display panel driving circuit 110 includes:

• a receiving circuit 111 receiving first color signals in an RGB system corresponding to a display panel and converting the first color signals into first color space signals in an HSV system;
• a color saturation adjustment circuit 112 adjusting a color saturation of the first color space signals by predetermined adjustment coefficients to obtain second color space signals in the HSV system; and converting the second color space signals into second color signals in the RGB system; and
• a first driving circuit 113 driving the display panel by the second color signals.

The backlight module driving circuit includes

• a light source adjustment calculation circuit 121 receiving the first color signals in the RGB system corresponding to the display panel, obtaining the first color space signals in the HSV system and the second color space signals in the HSV system, and obtaining a light source adjustment coefficient according to the first color space signals and the second color space signals;
• a light source adjustment circuit 122 adjusting a first brightness value corresponding to the first color light source and/or the second color light source by the light source adjustment coefficient to obtain a second brightness value; and
• a second driving circuit 123 the first color light sources and/or the second color light sources by the second brightness value.

FIG. 14 is a schematic diagram of a display device according to one embodiment of the present disclosure. As shown in FIG. 14, and combined with FIGS. 1 to 13, the present disclosure further provides a display device 200, including the driving system of the display module of the present disclosure.

It should be noted that the limitation of each step involved in the present disclosure is not determined to limit the sequence of steps without affecting the implementation of the specific solution. Steps written in the foregoing can be executed first, or later, or even simultaneously as long as the specific solutions can be implemented, which should be considered as the scope of the present disclosure.

The present disclosure is able to be applied on various display panels, such as a Twisted-Nematic (TN) type display panel, In-Plane Switching (IPS) type display panel, a Vertical-Alignment (VA) type display panel, and Multi-domain Vertical Alignment (MVA) type display panel. Of course, the display panel can be other types of display panels which is able to be applied, such as a Organic Light-Emitting Diode (OLED) display panel.

The above content is a further detailed description of the present disclosure in conjunction with the specific optional embodiments, and the specific implementation of the present disclosure is not limited to the description. It will be apparent to those skilled in the art that a number of simple deductions or substitutions may be made without departing from the conception of the present disclosure, which should be considered as being within the scope of the present disclosure.

Claims

1. A driving method of a display module, comprising a display panel driving process, and a backlight module driving process performed synchronously with the display, panel driving process; wherein the display module comprises a plurality of first color light sources and second color light sources, the first color light sources and the second color light sources are controlled independently;wherein the display panel driving process comprises:receiving first color signals in an RGB (Red, Green, Blue) system corresponding to a display panel, and converting the first color signals into first color space signals in an HSV (Hue, Saturation, Value) system;adjusting a color saturation of the first color space signals by predetermined adjustment coefficients to obtain second color space signals in the HSV system, and converting the second color space signals into second color signals in the RGB system; anddriving the display panel by the second color signals;wherein the backlight module driving process comprises:receiving the first color signals in the RGB system corresponding to the display panel, obtaining the first color space signals in the HSV system and the second color space signals in the HSV system, and obtaining a light source adjustment coefficient based on the first color space signals and the second color space signals;adjusting a first brightness value corresponding to the first color light sources and/or the second color light sources by the light source adjustment coefficient to obtain a second brightness value; anddriving the first color light sources and/or the second color light sources by the second brightness value;wherein the display module is a direct-lit backlight display module; the direct-lit backlight display module comprises a plurality of backlight partitions, each of the backlight partitions comprises the plurality of the first color light sources and the second color light sources that are independently controlled;wherein each of the backlight partitions further comprises a plurality of third color light sources; the third color light sources are controlled independently;wherein the obtaining the light source adjustment coefficient according to the first color space signals and the second color space signals comprises:obtaining the first color space signals and the second color space signals of all pixels in current backlight partitions corresponding to a current frame, calculating a first average color saturation signal corresponding to the first color space signals and a second average color saturation signal corresponding to the second color space signals respectively; andcalculating the light source adjustment coefficient based on the first average color saturation signal and the second average color saturation signal.

2. The driving method of the display module according to claim 1, wherein the predetermined adjustment coefficients are obtained by the following operations: obtaining color saturation signals of the first color space signals, wherein the predetermined adjustment coefficients are calculated based on the color saturation signals according to a predetermined calculation formula or by looking up in a predetermined adjustment coefficient look up table.

3. The driving method of the display module according to claim 2, wherein the adjusting the color saturation of the first color space signals by the predetermined adjustment coefficients comprises: obtaining current color saturation signals of the first color space signals, detecting whether the current color saturation signals satisfy a predetermined color saturation threshold, and detecting whether the current color saturation signals are in a hue interval to be adjusted, and in the case where the current color saturation signals of the first color space signals both satisfy the predetermined color saturation threshold and are in the hue interval to be adjusted, then obtaining the predetermined adjustment coefficients according to corresponding color saturation values and corresponding hue intervals of the current color saturation signals.

4. The driving method of the display module according to claim 3, wherein the color saturation signals are divided into at least a first hue interval, a second hue interval, and a third hue interval depending on different hues; wherein with respect to a same hue; the greater the color saturation values of the current color saturation signals, the greater an adjustment amplitude for the operation of adjusting the color saturation of the first color space signals.

5. The driving method of the display module according to claim 4, wherein the first hue interval, the second hue interval, and the third hue interval are defined as a red hue interval, a green hue interval, and a blue hue interval respectively; wherein in the current color saturation signals having a same color saturation value, the adjustment amplitude of the predetermined color adjustment signals corresponding to the blue hue interval to the current color saturation signals is greater than the adjustment amplitude of the predetermined color adjustment signals corresponding to the red hue interval to the current color saturation signals; the adjustment amplitude of the predetermined color adjustment signals corresponding to the red hue interval to the current color saturation signals is greater than the adjustment amplitude of the predetermined color adjustment signals corresponding to the green hue interval to the current color saturation signals.

6. The driving method of the display module according to claim 3, wherein the color saturation threshold is 0.5, and if the color saturation values of the current color saturation signals are greater than 0.5, the color saturation values of the current color saturation signals satisfy the color saturation threshold.

7. The driving method of the display module according to claim 3, wherein the color saturation threshold is more than 0.5 and less than 1.

8. The driving method of the display module according to claim 3, wherein a hue value ranges from 0-360, corresponding to 0-360 degrees; wherein a hue interval with a hue value satisfying the following formula is a red hue interval: 0≤Hue<40, or 320<Hue≤360;wherein the hue interval with a hue value satisfying the following formula is a green hue interval: 80<Hue<160;wherein the hue interval with a hue value satisfying the following formula is a blue hue interval: 40≤Hue≤80, or 160≤Hue≤200;wherein the hue interval with a hue value satisfying the following formula is a hue interval not to be adjusted: 40≤Hue≤80, or 160≤Hue≤200, or 280≤Hue≤320.

9. The driving method of the display module according to claim 2, wherein the adjustment coefficient look up table is a look up table directly recorded with predetermined adjustment coefficients, or is a look up table recording a predetermined calculation formula.

10. The driving method of the display module according to claim 9, wherein the second color space signals and the first color space signals satisfy the following formula: S′=a*S4+b*S3+c*S2+d*S+e; wherein S is the current color saturation signals corresponding to the first color space signals, and S′ is the color saturation signals corresponding to the second color space signals; the a, b, c, d, e are constants, the a, b, c, d, e are obtained by looking up in a predetermined formula coefficient look up table according to different color saturation values and different hue intervals.

11. The driving method of the display module according to claim 1, wherein calculating the light source adjustment coefficient comprises: calculating a first average color saturation signal corresponding to the first color space signals by formula Sn_ave=Average(Sn_1,1, Sn_1,2, . . . , Sn_i,j);calculating a second average color saturation signal corresponding to the second color space signals by formula S′n_ave=Average(S′n_1,1, S′n_1,2, . . . , S′n_i,j); andcalculating the light source adjustment coefficient based on the first average color saturation signal Sn_ave and the second average color saturation signal S′n_ave.

12. The driving method of the display module according to claim 11, wherein the converting the first color signals into first color space signals in the HSV system comprises: obtaining the first color signals Rn_i,j, Gn_i,j, Bn_i,j, and converting each group of RGB three primary color sub-pixel grayscale signals into three primary color normalized luminance signals r, g, b; and obtain first normalized luminance signals rn_i,j, gn_i,j, bn_i,j after completing the conversion;converting the first color signals into the first color space signals according to the first normalized luminance signals, where Sni,j=1−minni,j/maxni,j,wherein the adjusting the color saturation of the first color space signals by the predetermined adjustment coefficients to obtain the second color space signals in the HSV system comprises:keeping maxni,j unchanged while adjusting minni,j by the predetermined adjustment coefficients; andcompleting an adjustment of the color saturation signals to obtained the second color space signals in the HSV system S′=1−mini,j*H/maxi,j;wherein mini,j=min (rn_i,j, gn_i,j, bn_i,j), and maxi,j=max (rn_i,j, gn_i,j, bn_i,j).

13. The driving method of the display module according to claim 12, wherein the adjusting the color saturation of the first color space signals by the predetermined adjustment coefficients to obtain the second color space signals in the HSV system, and converting the second color space signals into the second color signals in the RGB system; and driving the display panel by the second color signals comprises: calculating third color saturation signals S″ based on the current color saturation signals S and the second color saturation signals S′;completing two times of color saturation adjustment; and obtaining the second color space signals in the HSV system based on the third color saturation signals; andconverting the second color space signals into the second color signals in the RGB system; anddriving the display panel by the second color signals.

14. The driving method of the display module according to claim 11, wherein the calculating the light source adjustment coefficient based on the first average color saturation signal and the second average color saturation signal comprises: calculating the first average color saturation signal by formula Sn_ave=1−minn_ave/maxn_ave;calculating the second average color saturation signal by formula S′n_ave=1−min′n_ave/max′n_ave; andadjusting the second average color saturation signal by the light source adjustment coefficient to obtain a third average color saturation signal S″n_ave;wherein the light source adjustment coefficient y satisfies following formulas: S″n_ave=Sn_ave;1−min n_ave/max n_ave=1−min′n_ave/(max′n_ave*y); andy=(S′n_ave−1)/(Sn_ave−1);wherein maxn_ave is a maximum average signal among a red sub-pixel average signal, a green sub-pixel average signal, and a blue sub-pixel average signal of the first color signals of all pixels in current backlight partitions corresponding to a current frame, and minn_ave is a minimum average signal among the red sub-pixel average signal, the green sub-pixel average signal, and the blue sub-pixel average signal of the first color signals of all pixels in the current backlight partitions corresponding to the current frame;wherein maxn_ave is also a maximum average signal of the second color signals among a red sub-pixel average signal, a green sub-pixel average signal, and a blue sub-pixel average signal of the second color signals of all pixels in the current backlight partitions corresponding to the current frame; and min′n_ave is a minimum average signal among the red sub-pixel average signal, the green sub-pixel average signal, and the blue sub-pixel average signal of the second color signals of all pixels in the current backlight partitions corresponding to the current frame.