Backlight control method and display panel

Abstract

This application belongs to the field of display technology, specifically relating to a backlight control method and a display panel, including: obtaining the screen type corresponding to the current backlight partition based on image data of the current backlight partition and adjacent backlight partitions; when the screen type is a preset screen type, controlling the red, green, and blue light-emitting diodes in the current backlight partition to be lit simultaneously during the first time period of the current display frame; controlling all light-emitting diodes in the current backlight partition to be turned off during the second time period after the first time period; and controlling only the light-emitting diodes of the target color in the current backlight partition to be lit during the third time period after the second time period. This application effectively improves the color overflow defect of RGB-MiniLED backlight at high contrast edges by controlling the backlight partition to sequentially perform white light illumination, black field isolation, and boundary color matching in one frame, and suppresses the color shift problem caused by the difference in light pattern divergence of different color chips under large viewing angles.

Description

Technical Field

[0001] This disclosure belongs to the field of display technology, specifically relating to a backlight control method and a display panel. Background Technology

[0002] As display technology develops towards ultra-wide color gamut, RGB three-primary-color Mini-LED (RGB-MiniLED) backlight technology has become a research hotspot due to its ability to natively cover wide color gamut standards such as BT.2020. In the RGB-MiniLED backlight architecture, each backlight zone is independently configured with red, green, and blue LED chips, and color mixing is achieved by adjusting the brightness ratio of each color chip.

[0003] However, existing RGB-MiniLED backlights have color mixing defects in practical applications: when multiple colors exist in the same zone at the same time, traditional backlight compensation methods directly illuminate the corresponding color light, resulting in severe color overflow (i.e., "color staining") at high contrast edges; in addition, the light pattern difference of different color chips under limited mixing distance will also cause color shift at a large viewing angle.

[0004] Therefore, how to effectively improve the color overflow defect of RGB-MiniLED backlight at high contrast edges is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] This application provides a backlight control method and a display panel. By controlling the backlight partition to sequentially perform white light illumination, black field isolation and boundary color matching in one frame, it effectively improves the color overflow defect of RGB-MiniLED backlight at high contrast edges and suppresses the color shift problem caused by the difference in light pattern divergence of different color chips under wide viewing angle.

[0006] In a first aspect, this application provides a backlight control method applied to a display panel, the display panel including multiple backlight zones, each backlight zone being configured with red, green, and blue light-emitting diodes (LEDs) that are independently controlled to turn on and off. The backlight control method includes: obtaining the screen type corresponding to the current backlight zone based on image data of the current backlight zone and adjacent backlight zones; when the screen type is a preset screen type, controlling the red, green, and blue LEDs in the current backlight zone to light up simultaneously during a first time period of the current display frame; controlling all LEDs in the current backlight zone to turn off during a second time period after the first time period; and controlling only the LEDs of the target color to light up during a third time period after the second time period; wherein, the preset screen type indicates that: the current backlight zone is a dual-color mixing zone containing a first color and a second color, and there exists at least one adjacent backlight zone that is a pure color zone with the same color as the first color or the second color; the target color is the color corresponding to the adjacent backlight zone.

[0007] Secondly, this application provides a display panel, the display panel comprising: a backlight module disposed on the back side of the display panel body, the backlight module comprising a plurality of backlight zones, each backlight zone being configured with a red light-emitting diode, a green light-emitting diode and a blue light-emitting diode that are independently controlled to turn on and off, and a backlight control circuit for driving the red light-emitting diode, the green light-emitting diode and the blue light-emitting diode; and a backlight control device connected to the backlight control circuit and configured as a backlight control method.

[0008] The technical solution provided in this application has at least the following beneficial effects:

[0009] This application achieves time-divisional display of two colors while eliminating color difference at the boundary of the partition by controlling the backlight partition to perform white light illumination, black field isolation and boundary color matching in a frame. This effectively improves the color overflow defect of RGB-MiniLED backlight at high contrast edges and suppresses the color shift problem caused by the difference in light pattern divergence of different color chips at a wide viewing angle. Attached Figure Description

[0010] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0011] Figure 1The diagram shown is a backlight partitioning diagram provided in an embodiment of this application.

[0012] Figure 2 The image shown is a schematic diagram of a preset screen type provided in an embodiment of this application.

[0013] Figure 3 The diagram shown is a schematic flowchart of a backlight control method provided in an embodiment of this application.

[0014] Figure 4 The figure shown is a timing diagram provided in an embodiment of this application.

[0015] Figure 5 As shown Figure 3 An exemplary process diagram of step S100.

[0016] Figure 6 The diagram shown is a schematic diagram of a backlight control circuit provided in an embodiment of this application.

[0017] Explanation of reference numerals in the attached figures: M1, first transistor; M2, second transistor; M3, third transistor; M4, fourth transistor; C1, first capacitor; C2, second capacitor; C3, third capacitor; C4, fourth capacitor; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; R5, fifth resistor; R6, sixth resistor; R7, seventh resistor; R8, eighth resistor; R9, ninth resistor; R10, tenth resistor; R11, eleventh resistor; RLED, red light-emitting diode; GLED, green light-emitting diode; BLED, blue light-emitting diode; VR, first power supply terminal; VG, second power supply terminal; VB, third power supply terminal. Detailed Implementation

[0018] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0019] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0020] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be noted that the technical features involved in the various embodiments described below can be combined with each other as long as they do not conflict with each other. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present application, and should not be construed as limiting the present application.

[0021] With the iterative upgrades of display technology, Mini-LED backlighting technology, with its refined local dimming capabilities, has become a standard solution for high-end display devices. Traditional white Mini-LED backlighting mainly uses a "blue light chip + phosphor" solution, where blue light excites the phosphor to produce white light. Although this solution is technically mature, its color gamut coverage is usually limited to within the DCI-P3 or sRGB standards due to the spectral characteristics of the phosphor, making it difficult to meet the requirements of ultra-wide color gamut standards such as BT.2020.

[0022] To overcome color gamut limitations, the industry has begun exploring and adopting a technology that uses RGB three-primary-color Mini-LED chips directly as backlights. This solution independently adjusts the brightness of the red, green, and blue chips, and uses color mixing principles to directly synthesize the desired colors. Theoretically, this can achieve native coverage of a wider color gamut and significantly improve color reproduction capabilities.

[0023] However, RGB-MiniLED backlighting faces significant challenges in color mixing technology during practical engineering applications. For example... Figure 1 As shown, in the RGB-MiniLED backlight architecture, the backlight is divided into multiple backlight zones, each typically controlled by only three R, G, and B LEDs. While the zone precision cannot achieve the pixel-level detail of Micro-LED, its cost and technical difficulty are far lower, making it highly valuable for production and application. In a pure color scene, to improve contrast, existing backlight algorithms control the individual illumination of LEDs of the corresponding color, resulting in purer colors. However, when multiple colors appear within the same zone, this compensation method can lead to color mixing, color cast, and color tinting issues.

[0024] Specifically, the challenge of color mixing is mainly reflected in the following two aspects: (1) Color overflow at high contrast edges (i.e., "color staining"): In the RGB zone backlight architecture, each backlight zone has its own independent color attributes. Compared with traditional white Mini-LED, the driving deviation of the white light scheme is mainly manifested as brightness overflow (halo), which has a relatively limited impact on the visual perception; however, any deviation in the light control timing, imbalance in brightness ratio, or abnormal zone coupling in the RGB scheme will directly lead to incorrect color presentation. For example Figure 2As shown, when the overall image is red, a white area appears in the center. Conventional LED backlight algorithms, to ensure red contrast, control the bottom backlight LEDs to illuminate red, and then use the corresponding position on the upper LCD panel for color compensation. However, because the backlight background is red, the actual white area displayed is noticeably reddish, resulting in "color staining." This color staining phenomenon is more sensitive to the human eye than uneven brightness, especially when displaying white text, high-contrast UI icons, cursors, and other detailed images. The defect is particularly prominent, severely damaging the purity of the image and the viewing experience.

[0025] (2) Color shift caused by uneven spatial color mixing: The RGB three-color chips have definite physical positional differences on the lamp board substrate. In the design of thin display devices, the mixing distance (OD value) is greatly compressed, resulting in the inability of light emitted from different angles to mix fully in a limited space. When the user views from the front, the RGB three-color light ratio is relatively balanced, and the picture presents an ideal white field effect; however, when the viewing angle increases to the side, due to the inconsistent light pattern divergence of different color chips (usually the divergence angle of red light is greater than that of blue and green light), the light intensity attenuation rate at each angle is different, resulting in local red, blue, or green color shifts in the side-view picture. This defect significantly weakens the color consistency under wide viewing angles and limits the application value of RGB-MiniLED in ultra-large size, ultra-thin displays and high ambient light contrast scenarios.

[0026] Therefore, in order to improve the color mixing effect of RGB-MiniLED and suppress color overflow at high contrast edges and color shift at large viewing angles, the inventors of this application propose a backlight control method, which specifically includes the following embodiments: Figure 3 The diagram shown is a schematic flowchart of a backlight control method provided in an embodiment of this application; it is applicable to display panels that use RGB three-primary-color Mini-LEDs as backlights. Figure 1 As shown, the backlight module of the display panel is divided into multiple backlight zones. Each backlight zone independently contains one red LED, one green LED, and one blue LED, and these three LEDs can be independently controlled to light up or turn off. Each backlight zone includes several sub-pixels. For example... Figure 3 As shown, the backlight control method of this embodiment includes the following steps: Step S100: Obtain the image type corresponding to the current backlight zone based on the image data of the current backlight zone and adjacent backlight zones.

[0027] It should be noted that this embodiment can obtain the image data of the current frame from the timing controller; wherein, the image data includes the pixel data of the screen area corresponding to the current backlight partition, and the pixel data of the screen areas corresponding to all adjacent backlight partitions, thereby analyzing the image type of the current backlight partition.

[0028] It is worth noting that the screen type in this embodiment is not determined solely by the current partition itself, but rather by a combination of information from adjacent partitions. The definition of the preset screen type in this embodiment includes: (1) the current backlight partition is a "dual-color mixing partition", that is, there are only two different colors in the screen area corresponding to this partition, referred to as the first color and the second color; (2) at the same time, there are at least one adjacent backlight partition (including the top, bottom, left, right and diagonal directions) that are solid color partitions, and the color of the solid color partition is the same as the first color or the second color in the current partition.

[0029] For example, in Figure 2 In the scene shown, the entire screen background is red, with a white graphic in the center. The backlight zone covered by the white graphic contains both red background pixels and white graphic pixels, making it a two-color mixed zone. All surrounding zones are pure red. Since the adjacent pure color zones share the same red color as the current zone, the conditions for the preset image type are met. Conversely, if the current zone is a pure color zone, a mixed color zone, or a two-color mixed zone without surrounding pure color zones of the same color, it does not belong to the preset image type and can use a conventional backlight compensation strategy (e.g., only lighting the corresponding color in pure color zones, and directly outputting white light in other cases), which will not be elaborated here.

[0030] Step S200: When the screen type is the preset screen type, in the first time period of the current display frame, control the red light-emitting diode, green light-emitting diode and blue light-emitting diode in the current backlight zone to light up simultaneously.

[0031] It should be noted that after determining that the current backlight zone belongs to the preset screen type, in the first time period of the current display frame (e.g., Figure 4 During the t1 time period, a control signal is output to simultaneously illuminate the red, green, and blue LEDs within the current backlight zone. At this time, the three colors of light are mixed to output white light, providing a neutral and unbiased illumination basis for the LCD panel. This allows different display areas within the zone to achieve accurate color reproduction through transmittance modulation of the LCD panel, avoiding color shift in one color due to a single backlight color.

[0032] Step S300: In the second period following the first period, control all light-emitting diodes in the current backlight zone to turn off.

[0033] It should be noted that the second period begins immediately after the first period ends, such as... Figure 4 During the t2 time period, all LEDs in the current backlight zone are turned off, i.e., a black field is inserted. In this embodiment, the purpose of inserting a black field is to completely separate the white light of the previous time period from the monochromatic light of the next time period in time. This utilizes the intermittent perception characteristic of human vision, allowing the brain to treat the two light-emitting events as independent images, thereby simultaneously obtaining correct white reproduction and correct background color reproduction. This avoids the mixing of continuous white light and monochromatic light due to visual persistence, which would cause the background color to be diluted by the white light, resulting in increased grayscale or color shift.

[0034] Step S400: In the third time period after the second time period, control the current backlight zone to only light up the LEDs of the target color.

[0035] It should be noted that after the second period ends, the third period begins, such as... Figure 4 During the t3 time period, only the monochrome LEDs corresponding to the target color are illuminated within the current backlight zone. The target color is the same color as the adjacent solid color zone, that is, the color shared by the current zone and the adjacent solid color zone.

[0036] by Figure 2 For example, if the adjacent solid color zone is red, then the target color is also red. Therefore, in the third time period, only the red LEDs in the current zone are lit, while the green and blue LEDs remain off. This enhances the brightness of the background color within the current zone, ensuring it matches the brightness and color of the surrounding solid color zones, thus avoiding the decrease in contrast caused by the pale background color in the first time period. Since only monochromatic light is output in the third time period, and the surrounding solid color zones also use the same monochromatic light, the two blend together visually, eliminating color differences at the zone boundaries.

[0037] In another embodiment, a black insertion period is included before the first time period of the current display frame, and a black insertion period is also included after the third time period; specifically as follows: Figure 4 As shown, within a complete display frame cycle, the backlight emission timing actually includes five periods, namely: the pre-black period, the first period, the second period, the third period, and the post-black period. Among them, the first period, the second period, and the third period are the core emission control periods of this application, while the pre-black period is located at the beginning of each display frame and is mainly used to eliminate the visual persistence of the previous frame, so that the human eye returns to the dark reference state before receiving the image of the current frame, avoiding visual crosstalk between the previous and subsequent frames. In addition, the post-black period is located at the end of each display frame and is mainly used to ensure that the emission of the current frame is completely finished within the current frame, providing a clean dark background for the start of the next frame.

[0038] In summary, this application determines whether the current backlight partition is a preset screen type based on the image data of the current backlight partition and its adjacent backlight partitions. This ensures that subsequent timing control is only triggered in scenarios with the highest risk of color distortion at high contrast edges, avoiding unnecessary timing switching that interferes with the normal screen. Furthermore, when a preset screen type is detected, this application divides the backlight emission timing within a display frame into a white light period, a black field period, and a monochromatic light period, which are executed sequentially. Specifically, during the white light period, red, green, and blue LEDs are lit simultaneously, and the output full-spectrum white light enables the display panel to modulate accurate colors, eliminating the problem of color distortion caused by a single color backlight from the backlight side. During the monochromatic light period, only LEDs of the same color as the adjacent pure color partition are lit, so that the display area of ​​the same color as the adjacent partition within the current partition obtains the same brightness and color performance as the surrounding area, thereby eliminating visual differences at the partition boundaries. Finally, the black field period inserted in the middle utilizes the persistence of vision of the human eye to perceptually separate the two emission periods, preventing them from mixing and producing new color distortion.

[0039] Therefore, this application achieves time-divisional satisfaction of two color display requirements while eliminating color difference at the partition boundary by controlling the backlight partition to sequentially perform white light illumination, black field isolation and boundary color matching in one frame. This can effectively improve the color overflow defect of RGB-MiniLED backlight at high contrast edges and suppress the color shift problem caused by the difference in light pattern divergence of different color chips at a large viewing angle.

[0040] Figure 5 As shown Figure 3 An exemplary flowchart of step S100; as shown Figure 5 As shown, based on the image data of the current backlight zone and adjacent backlight zones, the image type corresponding to the current backlight zone is obtained, specifically including the following steps: Step S110: Obtain the first image data block corresponding to the current backlight partition, and multiple second image data blocks corresponding to all adjacent backlight partitions.

[0041] Step S120: Determine the partition type corresponding to the first image data block based on the hue value of each pixel in the first image data block.

[0042] Specifically, each pixel in the current image data block undergoes color space conversion to obtain its hue value. Based on the hue value of each pixel, the number of different hue values ​​in the current image data block is counted and used as the hue level corresponding to the current image data block. The hue variance of the current image data block is obtained based on the hue value of each pixel and the average hue of all pixels. The hue gradient of the current image data block is obtained based on the average of the absolute hue differences between all adjacent pixel pairs. When the hue level is equal to 1, the hue variance is equal to 0, and the hue gradient is equal to 0, the current image data block is determined to be a solid color partition. When the hue level is equal to 2, the hue variance is greater than 0 and less than the variance threshold, and the hue gradient is greater than 0 and less than the gradient threshold, the current image data block is determined to be a two-color mixed partition. When the hue level is greater than or equal to 3, the hue variance is greater than or equal to the variance threshold, and the hue gradient is greater than or equal to the gradient threshold, the current image data block is determined to be a noisy partition.

[0043] Step S130: When the partition type in the first image data block is a two-color mixed partition, the hue value with a high pixel proportion is used as the first color, and the hue value with a low pixel proportion is used as the second color.

[0044] Step S140: Determine the partition type corresponding to each second data block based on the hue value of each pixel in each second image data block.

[0045] Step S150: When at least one second data block has a partition type of solid color partition, and the main color of the solid color partition is the same as the first color or the second color, then the screen type corresponding to the current backlight partition is the preset screen type.

[0046] It should be noted that this embodiment mainly determines whether the current backlight zone is a preset screen type or a normal screen type, specifically including the following process: (1) Color space conversion and hue value extraction: For any image data block, the RGB color components of each pixel are first converted to the HSV color space, and the hue components of each pixel are extracted. Hue is a parameter that describes the essential attributes of color. It is independent of brightness and saturation and can more accurately reflect the essential category of color, which is convenient for subsequent statistics and judgment. It is represented by angle values ​​from 0° to 360°. For example, red corresponds to 0°, green corresponds to 120°, and blue corresponds to 240°. After conversion, each pixel obtains a specific hue value.

[0047] (2) Partition type determination of a single image data block: For the current image data block to be determined, the following three statistics are calculated: ① Tone Levels: Count the tone values ​​of all pixels in the data block and record the number of different tone values, denoted as the tone levels N. For example, if the tone value of all pixels is 0° (red), then N=1; if the pixel tone values ​​are only 0° and 120°, then N=2; if there are three or more different tone values, then N≥3.

[0048] ② Tone variance: First, calculate the average of the tone values ​​of all pixels, then calculate the average of the squared deviations of the tone value of each pixel from the average value to obtain the tone variance V. Variance reflects the dispersion of tone distribution: the smaller the variance, the more concentrated the pixel tones; the larger the variance, the more dispersed the tones.

[0049] ③ Tonal gradient: For each pair of adjacent pixels within an image data block, the average of the absolute differences in their tones is calculated to obtain the tonal gradient G. The gradient reflects the degree of color change in the image: the smaller the gradient, the smoother the color transition; the larger the gradient, the sharper the color boundary.

[0050] ④ Judgment Rules: When N=1, V=0, and G=0, it is judged as a solid color partition. At this time, all pixels in the data block have the same hue and there is no color change; when N=2, 0<V<V_th, and 0<G<G_th, it is judged as a two-color mixed partition. Here, V_th is a preset variance threshold, and G_th is a preset gradient threshold. At this time, there are two different hues in the data block, and the transition between the two hues is relatively smooth (the gradient is not large), and the variance is moderate; when N≥3, V≥V_th, and G≥G_th, it is judged as a mixed color partition. At this time, there are three or more hues, the color distribution is scattered, and the boundaries are complex.

[0051] (3) Comprehensive determination of preset image type: After determining the current backlight zone, if the zone is determined to be a two-color mixed zone, the determination results of adjacent zones are further analyzed. Specifically: First, within the current backlight zone, the color corresponding to the hue value with the high pixel proportion is taken as the first color, and the color corresponding to the hue value with the low pixel proportion is taken as the second color. For example, if red pixels account for 70% and green pixels account for 30% in the current zone, then the first color is red and the second color is green. Then, all adjacent backlight zones are traversed to check whether there is at least one adjacent zone that meets the following two conditions: the adjacent zone is determined to be a solid color zone, and the main color of the solid color zone is the same as the first color or the second color of the current zone.

[0052] If such an adjacent partition exists, the image type of the current backlight partition is determined to be the preset image type; at this time, the main color of the adjacent partition is the target color that needs to be lit in the subsequent third time period. If there are no adjacent partitions that meet the conditions (for example, adjacent partitions are all mixed color partitions, or although they are solid colors, the colors are different from the two colors of the current partition), the image type of the current backlight partition is the normal image type, and a control method can be adopted, such as lighting only the corresponding color in solid color partitions, and directly outputting white light in other cases.

[0053] Therefore, by calculating three statistical measures—hue level, variance, and gradient—this application can accurately identify the specific type of backlight zone.

[0054] In one embodiment, the backlight control method provided by this application further includes: obtaining the pixel set corresponding to the second color within the current backlight partition; calculating the ratio of the number of pixels corresponding to the second color to the total number of pixels within the current backlight partition to obtain the area ratio of the second color within the current backlight partition; determining the initial duration ratio of the first time period and the third time period based on the area ratio; weighting the initial duration ratio with the actual duration ratio of the previous display frame to obtain the actual duration ratio of the current display frame; and controlling the actual duration of the first time period and the third time period in the current display frame based on the actual duration ratio.

[0055] Furthermore, based on the area proportion, the initial duration ratio between the first and third time periods is determined, specifically including: when the area proportion is less than or equal to a first preset threshold, the initial duration ratio is determined as a first fixed ratio, in which the duration of the first time period is less than the duration of the third time period; when the area proportion is greater than or equal to a second preset threshold, the initial duration ratio is determined as a second fixed ratio, in which the duration of the first time period is greater than the duration of the third time period; wherein, the first preset threshold is less than the second preset threshold; when the area proportion is greater than the first preset threshold and less than the second preset threshold, the variable duration ratio between the first and third time periods is calculated according to a monotonically increasing function, and the variable duration ratio is used as the initial duration ratio.

[0056] It should be noted that this embodiment mainly adjusts the duration ratio of the first time period and the third time period based on the area ratio of colors within the current backlight partition, and ensures the stability of brightness changes through inter-frame smoothing filtering. Specifically, it includes the following steps: (1)Obtaining the area ratio: After determining that the current backlight zone is of the preset picture type, this embodiment further analyzes the distribution of the second color within this zone. Specifically, all the pixels belonging to the second color are extracted from the first image data block corresponding to the current backlight zone, the number N_second of these pixels is counted, and divided by the total number N_total of pixels within this zone to obtain the area ratio S = N_second / N_total of the second color.

[0057] (2)Determining the initial duration ratio according to the area ratio: The duration ratio R between the first period and the third period determines the relative intensities of white light illumination and monochromatic light illumination. The larger the area ratio S, the wider the area covered by the second color, and a longer white light segment is required to provide correct illumination for it; conversely, the smaller the area ratio S, the background color dominates, and a longer monochromatic light segment is required to match the surrounding pure color zones. This embodiment divides the value range of the area ratio S into three intervals and adopts different determination methods: ① Low ratio interval (S ≤ S_low): When the area ratio of the second color is less than or equal to the first preset threshold S_low (for example, S_low = 0.1), it indicates that the foreground area is very small and the background color dominates absolutely. At this time, the white light segment should not be too long, otherwise it will dilute the background color. Therefore, the duration ratio is set to the first fixed ratio R_min, where T_white < T_color. For example, R_min = 1 : 3, that is, the duration of the white light segment accounts for 1 part and the duration of the monochromatic light segment accounts for 3 parts.

[0058] ② High ratio interval (S ≥ S_high): When the area ratio of the second color is greater than or equal to the second preset threshold S_high (for example, S_high = 0.8), it indicates that the foreground area is very large and almost covers the entire zone, and the background color only exists in the edge or sporadic areas. At this time, the accurate illumination of the foreground should be ensured first, so the duration ratio is set to the second fixed ratio R_max, where T_white > T_color. For example, R_max = 3 : 1, that is, the duration of the white light segment accounts for 3 parts and the duration of the monochromatic light segment accounts for 1 part.

[0059] ③ Medium ratio interval (S_low < S < S_high): When the area ratio is between the two thresholds, a monotonically increasing function is used to calculate the variable duration ratio R_var, such that R continuously changes from R_min to R_max as S increases. The monotonically increasing function can be a linear function (such as R = R_min + (R_max - R_min) (S - S_low) / (S_high - S_low)), or a logarithmic function or a look-up table mapping. This embodiment preferably uses a linear function, which is simple to implement and has a smooth transition.

[0060] Through the above segmented processing, this embodiment avoids excessive dilution of the background color by the white light segment when the area ratio S is extremely small, ensures sufficient illumination of the foreground when the area ratio S is extremely large, and achieves a continuous transition in the middle area, avoiding visual abruptness caused by abrupt changes in proportion.

[0061] (3) Inter-frame weighted average smoothing: Since the content between adjacent frames in a video frame is usually continuous, the area ratio S of the second color will not change drastically. However, in order to avoid brightness flicker that is perceptible to the human eye due to duration ratio jitter caused by image noise or fast movement, this embodiment performs low-pass filtering on the duration ratio in the time domain. Specifically, the initial duration ratio R_initial of the current display frame determined according to the area ratio is weighted and averaged with the final actual duration ratio R_prev of the previous display frame to obtain the final actual duration ratio R_current of the current frame: R_current = α×R_initial + (1-α) ×R_prev(1) In formula (1), α is the smoothing coefficient, ranging from 0 to 1. The larger α is, the greater the initial proportional weight of the current frame, and the faster the response; the smaller α is, the greater the proportional weight of the historical frames, and the stronger the smoothing effect. In this embodiment, α of 0.3 to 0.5 is more suitable, which can achieve a balance between response speed and smoothness. After weighted averaging, the actual duration of the first and third time periods is controlled according to the actual proportional duration R_current.

[0062] In one embodiment, the backlight control method further includes: constructing a hue value matrix based on the hue value of each pixel in the first image data block; performing edge detection on the hue value matrix to identify the set of boundary pixels between the first color and the second color; for each boundary pixel in the set of boundary pixels, calculating a first gradient value in the horizontal direction and a second gradient value in the vertical direction for each boundary pixel; calculating a comprehensive gradient value for each boundary pixel based on the first gradient value and the second gradient value for each boundary pixel; statistically analyzing the comprehensive gradient values ​​of all boundary pixels to obtain the edge gradient value at the color boundary; and determining the duration of the second time period based on the edge gradient value.

[0063] Optionally, the duration of the second time period is determined based on the edge gradient value, including: when the edge gradient value is less than or equal to the first gradient threshold, the duration of the second time period is set to a first fixed duration; when the edge gradient value is greater than or equal to the second gradient threshold, the duration of the second time period is set to a second fixed duration; wherein the second fixed duration is greater than the first fixed duration, and the first gradient threshold is less than the second gradient threshold; when the edge gradient value is greater than the first gradient threshold and less than the second gradient threshold, the variable duration of the second time period is calculated according to a monotonically increasing function.

[0064] It should be noted that this embodiment mainly adjusts the duration of the second time period based on the edge gradient value between the first color and the second color within the current backlight zone, in order to further optimize the color mixing effect. Specifically: (1) Calculation of edge gradient: After determining that the current backlight zone is a preset image type, this embodiment further analyzes the sharpness of the color boundary between the first color and the second color in the current zone. The sharper the color boundary, the higher the sensitivity of the human eye to color tint, and a longer black field is needed to force the separation of the two light-emitting segments; conversely, if the color boundary is gentle, a shorter black field can meet the visual separation requirements; the specific calculation process is as follows: ① Constructing the tone value matrix: First, extract the tone value of each pixel from the first image data block corresponding to the current backlight partition, forming a two-dimensional matrix, denoted as H. Let H(i,j) represent the tone value of the pixel located in the i-th row and j-th column. For example, if the current partition contains M rows and N columns of pixels, then the size of the tone value matrix is ​​M×N.

[0065] ② Identify the boundary pixel set: Perform edge detection on the hue value matrix to identify the boundary pixels between the first color and the second color, and form the boundary pixel set Ω by constructing all the pixels detected as boundaries.

[0066] ③ Calculate the horizontal and vertical gradients of each boundary pixel: For each pixel (i,j) in the boundary pixel set Ω, calculate its gradient values ​​in the horizontal and vertical directions using the central difference formula. The horizontal gradient is G_x(i,j) = |H(i+1,j) - H(i-1,j)| / 2, and the vertical gradient is G_y(i,j) = |H(i,j+1) - H(i,j-1)| / 2; where H(i,j) is the hue value at position (i,j). For pixels located at the image edge, one-sided difference or mirror fill methods can be used, which will not be elaborated here.

[0067] ④ Calculate the combined gradient value for each boundary pixel: Combine the horizontal and vertical gradients of each boundary pixel into a combined gradient value.

[0068] ⑤ Statistically obtain the overall edge gradient value: Statistically calculate the comprehensive gradient values ​​of all pixels in the boundary pixel set Ω, and obtain an edge gradient value G_edge that represents the overall sharpness of the color boundary within the current partition by taking the average value.

[0069] (2) Determining the duration of the black screen based on the edge gradient value: In this embodiment, the edge gradient value G_edge is compared with the first gradient threshold G_low and the second gradient threshold G_high, and the duration T_black of the second time period is determined in a segmented manner. Specifically: ① Low gradient interval (G_edge ≤ G_low): When the edge gradient value is less than or equal to the first gradient threshold, it indicates that the boundary between the first color and the second color is relatively gentle, and the color transition region is relatively wide. In this case, the human eye has a relatively low sensitivity to color staining at the boundary, and a short black field can separate the white light segment and the monochromatic light segment perceptually. Therefore, set T_black to the first fixed duration T_black_min (e.g., 0.5 ms).

[0070] ② High gradient interval (G_edge ≥ G_high): When the edge gradient value is greater than or equal to the second gradient threshold, it indicates that the color boundary is extremely sharp, and there is almost no transition region between the first color and the second color. At this time, the human eye is very sensitive to the color mutation at the boundary and is easy to capture color staining. To completely separate the white light segment and the monochromatic light segment, a longer black field is required. Therefore, set T_black to the second fixed duration T_black_max (e.g., 2 ms), where T_black_max > T_black_min.

[0071] ③ Medium gradient interval (G_low < G_edge < G_high): When the edge gradient value is between the two thresholds, calculate the variable duration T_black_var according to a monotonically increasing function, so that T_black continuously increases from T_black_min to T_black_max as G_edge increases. The monotonically increasing function can be a linear function, a logarithmic function, or a look-up table mapping.

[0072] It should be noted that the edge gradient adjustment in this embodiment can be used in cooperation with the aforementioned area ratio adjustment. That is, the area ratio is used to determine the duration ratio of the white light segment and the monochromatic light segment, and the edge gradient is used to determine the absolute duration of the black field, jointly constituting a complete backlight timing of the display frame.

[0073] In an embodiment, the backlight control method further includes: obtaining the position coordinates of multiple backlight partitions of the current backlight partition; calculating the row delay amount and the column delay amount of the current backlight partition according to the position coordinates, and taking the sum of the row delay amount and the column delay amount as the total delay amount; taking the modulus of the total delay amount with respect to the frame period of the display frame to obtain the actual delay amount; using the moment when the frame start moment of the current display frame plus the actual delay amount as the frame start delay moment of the current backlight partition, and sequentially performing the light emission control of the first period, the second period, and the third period.

[0074] It should be noted that in RGB-MiniLED backlighting, even if each zone controls its own white light segment, black light segment, and monochromatic light segment according to the method described in the above embodiment, if adjacent zones are lit simultaneously, their emitted light will still mix to some extent in space, especially near the zone boundaries. This mixing may lead to unwanted color superposition, for example, the edge light of the red zone may penetrate into the edge of the adjacent white zone, producing a faint pink halo. To further suppress color coupling between zones, this embodiment introduces a staggered lighting strategy in the temporal domain: the zones in different spatial locations emit light at staggered times, so that the light emission periods of adjacent zones no longer overlap. Since the human eye has low sensitivity to high-frequency temporal misalignment, this misalignment is almost imperceptible visually, but the degree of spatial mixing of light is greatly reduced due to the non-overlapping time. Specifically, this includes the following steps: (1) Obtain the position coordinates of the current backlight partition: Each backlight partition has unique two-dimensional coordinates in the backlight module, usually represented by row number r and column number c, where r=1,2,…,R_max, c=1,2,…,C_max. The backlight control device can obtain the coordinates (r,c) of the current partition by looking up the partition number in a table or by hardware address mapping.

[0075] (2) Calculate row and column delays: In this embodiment, the row delay ΔT_row and column delay ΔT_col of the current partition are calculated based on the position coordinates. The row delay is only related to the row number, and the column delay is only related to the column number. Specifically, an accumulation method can be used: ΔT_row = (r-1) × δ_row, ΔT_col = (c-1) × δ_col, where δ_row and δ_col are the unit delay steps in the row and column directions, respectively.

[0076] (3) Calculate the total latency: Add the row latency to the column latency to get the total latency of the current partition ΔT_total = ΔT_row + ΔT_col. In this way, partitions in different rows and columns will have different total latency. For example, for the partition located at (2,3), if δ_row=100μs and δ_col=80μs, then ΔT_total = (2-1)×100 + (3-1)×80 = 100 + 160 = 260μs.

[0077] (4) Modulo Frame Period: Since the display frames are periodically repeated, if the total delay exceeds one frame period T_frame, the delay will accumulate into the next frame, causing control chaos. Therefore, in this embodiment, the total delay is modulo the frame period to obtain the actual delay ΔT_actual = ΔT_total mod T_frame. The modulo operation ensures that the actual delay is always less than the frame period, while preserving the relative delay differences between different partitions. For example, if T_frame = 8.3ms (120Hz) and ΔT_total = 10ms for a certain partition, then ΔT_actual = 10 mod 8.3 = 1.7ms. This partition will start executing the emission timing of this frame 1.7ms after the start of the frame, which is equivalent to a delay of 1.7ms.

[0078] (5) Determine the frame start delay time and execute the light emission control: Based on the frame start time t_start of the current display frame, add the actual delay amount ΔT_actual to obtain the frame start delay time t_delay = t_start + ΔT_actual for this partition. Then, starting from the t_delay time, execute the light emission control for the first time period (white light), the second time period (black field), and the third time period (monochrome light) in sequence.

[0079] Therefore, the delayed lighting logic in this embodiment works in conjunction with the aforementioned white light segment, black field segment, and monochrome light segment timing. The delayed logic determines when each partition starts executing the three timing segments within a frame period. The duration allocation of the three timing segments is determined by the image content such as area ratio and edge gradient, thereby ensuring the accuracy of color mixing within each partition and suppressing mutual interference between partitions.

[0080] In one embodiment, this application provides a display panel, the display panel including: The backlight module is located on the back of the display panel body. The backlight module includes multiple backlight zones. Each backlight zone is equipped with red light-emitting diodes, green light-emitting diodes, and blue light-emitting diodes that are independently controlled to turn on and off, as well as a backlight control circuit for driving the red light-emitting diodes, green light-emitting diodes, and blue light-emitting diodes. A backlight control device, connected to a backlight control circuit, is configured to execute the backlight control method described in the above embodiments.

[0081] like Figure 6As shown, the backlight control circuit includes a first transistor M1, a second transistor M2, a third transistor M3, and a fourth transistor M4. The control terminal of the first transistor M1 is connected to the main control terminal of the backlight control device. The first terminal of the first transistor M1 is connected to the cathode of the red light-emitting diode RLED, the cathode of the green light-emitting diode GLED, and the cathode of the blue light-emitting diode BLED, respectively. The second terminal of the first transistor M1 is grounded. The control terminal of the second transistor M2 is connected to the first sub-control terminal of the backlight control device. The first terminal of the second transistor M2 is connected to the cathode of the red light-emitting diode RLED, and the second terminal of the second transistor M2 is grounded. The control terminal of the third transistor M3 is connected to the second sub-control terminal of the backlight control device. The first terminal of the third transistor M3 is connected to the cathode of the green light-emitting diode GLED, and the second terminal of the third transistor M3 is grounded. The control terminal of the fourth transistor M4 is connected to the third sub-control terminal of the backlight control device. The first terminal of the fourth transistor M4 is connected to the cathode of the blue light-emitting diode BLED, and the second terminal of the fourth transistor M4 is grounded.

[0082] It should be noted that the backlight control circuit in each backlight zone contains four transistors. The first transistor M1 acts as a master switch, simultaneously controlling the red LED (RLED), green LED (GLED), and blue LED (BLED). The second transistor M2 is used to control the red LED (RLED) individually, the third transistor M3 is used to control the green LED (GLED) individually, and the fourth transistor M4 is used to control the blue LED (BLED) individually. In this embodiment, the anode of the red LED (RLED) is connected to the first power supply terminal VR through the first resistor R1, the anode of the green LED (GLED) is connected to the second power supply terminal VG through the second resistor R2, and the anode of the blue LED (BLED) is connected to the third power supply terminal VB through the third resistor R3.

[0083] The working principle of the backlight control circuit in this embodiment is as follows: (1) In the first time period: the main control signal CKW output by the backlight control device is high level, the first sub-control signal CKR, the second sub-control signal CKG and the third sub-control signal CKB are all low level, then the first transistor M1 is turned on, the second transistor M2, the third transistor M3 and the fourth transistor M4 are all turned off, so all three light-emitting diodes (LEDs) are lit up and white light is output.

[0084] (2) During the second period: the main control signal CKW, the first sub-control signal CKR, the second sub-control signal CKG and the third sub-control signal CKB output by the backlight control device are all at low level. The first transistor M1, the second transistor M2, the third transistor M3 and the fourth transistor M4 are all cut off. The cathodes of all light-emitting diodes are disconnected from the ground, and all light-emitting diodes are extinguished, forming a black field.

[0085] (3) During the third time period: the main control signal CKW output by the backlight control device is at a low level, the first transistor M1 is cut off, only the sub-control terminal corresponding to the target color is at a high level, and the other sub-control terminals are at a low level. At this time, only the cathode of the target color LED is lit by grounding through its sub-control transistor, and the cathodes of other color LEDs have no grounding path and remain off.

[0086] like Figure 6 As shown, in this embodiment, the control terminal of the first transistor M1 is also grounded through the first capacitor C1, the first terminal of the first transistor M1 is connected to the cathode of all light-emitting diodes through the fourth resistor R4, and the second terminal of the first transistor M1 is also grounded through the fifth resistor R5; the control terminal of the second transistor M2 is also grounded through the second capacitor C2, the first terminal of the second transistor M2 is connected to the cathode of the red light-emitting diode RLED through the sixth resistor R6, and the second terminal of the second transistor M2 is also grounded through the seventh resistor R7; the control terminal of the third transistor M3 is also grounded through the third capacitor C3, the first terminal of the third transistor M3 is connected to the cathode of the green light-emitting diode GLED through the eighth resistor R8, and the second terminal of the third transistor M3 is also grounded through the ninth resistor R9; the control terminal of the fourth transistor M4 is also grounded through the fourth capacitor C4, the first terminal of the fourth transistor M4 is connected to the cathode of the blue light-emitting diode BLED through the tenth resistor R10, and the second terminal of the fourth transistor M4 is also grounded through the eleventh resistor R11.

[0087] It should be noted that the backlight control circuit of this embodiment adds several resistor and capacitor components to improve stability and reliability. Among them, the first capacitor C1, the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 in this embodiment mainly play the role of filtering and preventing false triggering; the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10 and the eleventh resistor R11 mainly play the role of current limiting.

[0088] Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0089] In the description of this specification, references to terms such as "some embodiments," "exemplarily," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. The illustrative expressions of the above terms in this specification do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0090] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application. Therefore, any changes or modifications made in accordance with the claims and description of this application should fall within the scope of this patent application.

Claims

1. A backlight control method, characterized in that, Applied to a display panel, the display panel includes multiple backlight zones, each backlight zone being configured with independently controllable red, green, and blue light-emitting diodes (LEDs), and the backlight control method includes: Based on the image data of the current backlight zone and adjacent backlight zones, obtain the image type corresponding to the current backlight zone; When the screen type is a preset screen type, during the first time period of the current display frame, control the red LED, green LED and blue LED in the current backlight zone to light up simultaneously; In the second period following the first period, all light-emitting diodes in the current backlight zone are turned off. In the third period following the second period, control the current backlight zone to only illuminate the light-emitting diodes of the target color; The preset screen type indicates that the current backlight partition is a two-color mixed partition containing a first color and a second color, and there is at least one adjacent backlight partition that is a pure color partition with the same color as the first color or the second color; the target color is the color corresponding to the adjacent backlight partition.

2. The backlight control method according to claim 1, characterized in that, Based on the image data of the current backlight zone and adjacent backlight zones, the image type corresponding to the current backlight zone is obtained, including: Obtain the first image data block corresponding to the current backlight partition, and multiple second image data blocks corresponding to all adjacent backlight partitions; Based on the hue value of each pixel in the first image data block, the partition type corresponding to the first image data block is determined; wherein, the partition type includes solid color partition, non-saturated color partition and two-color mixed partition; When the partition type in the first image data block is the two-color mixing partition, the hue value with a high pixel proportion is used as the first color, and the hue value with a low pixel proportion is used as the second color; Based on the hue value of each pixel in each second image data block, determine the partition type corresponding to each second data block; When at least one second data block has a solid color partition type, and the main color of the solid color partition is the same as the first color or the second color, then the screen type corresponding to the current backlight partition is the preset screen type.

3. The backlight control method according to claim 2, characterized in that, Determining the partition type of the first image data block based on the hue value of each pixel in the first image data block, and / or determining the partition type of each second data block based on the hue classification of each pixel in each second image data block, including: Perform color space conversion on each pixel in the current image data block to obtain the hue value of each pixel; Based on the hue value of each pixel, the number of different hue values ​​in the current image data block is counted and used as the hue level corresponding to the current image data block; The hue variance of the current image data block is obtained based on the hue value of each pixel and the average hue value of all pixels. The hue gradient of the current image data block is obtained by averaging the absolute hue differences between all adjacent pixel pairs. When the hue level is equal to 1, the hue variance is equal to 0, and the hue gradient is equal to 0, the current image data block is determined to be a solid color partition; When the hue level is equal to 2, the hue variance is greater than 0 and less than the variance threshold, and the hue gradient is greater than 0 and less than the gradient threshold, the current image data block is determined to be a two-color mixed partition. When the hue level is greater than or equal to 3, the hue variance is greater than or equal to the variance threshold, and the hue gradient is greater than or equal to the gradient threshold, the current image data block is determined to be a noisy partition.

4. The backlight control method according to claim 2, characterized in that, The backlight control method further includes: Obtain the set of pixels corresponding to the second color within the current backlight partition; The area ratio of the second color in the current backlight partition is obtained by calculating the ratio of the number of pixels corresponding to the second color to the total number of pixels in the current backlight partition. Based on the area ratio, the initial duration ratio between the first time period and the third time period is determined; The weighted average of the initial duration ratio and the actual duration ratio of the previous display frame is used to obtain the actual duration ratio of the current display frame. Based on the actual duration ratio, the actual duration of the first time period and the third time period in the current display frame is controlled.

5. The backlight control method according to claim 4, characterized in that, Based on the area ratio, the initial duration ratio between the first time period and the third time period is determined, including: When the area ratio is less than or equal to a first preset threshold, the initial duration ratio is determined as a first fixed ratio, wherein the duration of the first time period in the first fixed ratio is less than the duration of the third time period. When the area ratio is greater than or equal to the second preset threshold, the initial duration ratio is determined as the second fixed ratio, wherein the duration of the first time period in the second fixed ratio is greater than the duration of the third time period; wherein the first preset threshold is less than the second preset threshold; When the area ratio is greater than the first preset threshold and less than the second preset threshold, the variable duration ratio of the first time period and the third time period is calculated according to a monotonically increasing function, and the variable duration ratio is used as the initial duration ratio.

6. The backlight control method according to claim 2, characterized in that, The backlight control method further includes: A tone value matrix is ​​constructed based on the tone value of each pixel in the first image data block; Edge detection is performed on the hue value matrix to identify the set of boundary pixels between the first color and the second color; For each boundary pixel in the set of boundary pixels, calculate the first gradient value in the horizontal direction and the second gradient value in the vertical direction for each boundary pixel; Calculate the combined gradient value of each boundary pixel based on the first gradient value and the second gradient value of each boundary pixel; The edge gradient value at the color boundary is obtained by statistically analyzing the combined gradient values ​​of all boundary pixels. The duration of the second time period is determined based on the edge gradient value.

7. The backlight control method according to claim 6, characterized in that, The duration of the second time period is determined based on the edge gradient value, including: When the edge gradient value is less than or equal to the first gradient threshold, the duration of the second time period is set to the first fixed duration. When the edge gradient value is greater than or equal to the second gradient threshold, the duration of the second time period is set to a second fixed duration; wherein the second fixed duration is greater than the first fixed duration, and the first gradient threshold is less than the second gradient threshold; When the edge gradient value is greater than the first gradient threshold and less than the second gradient threshold, the variable duration of the second time period is calculated according to a monotonically increasing function.

8. The backlight control method according to any one of claims 1-7, characterized in that, The backlight control method further includes: Obtain the position coordinates of the multiple backlight zones in the current backlight partition; Based on the location coordinates, calculate the row delay and column delay of the current backlight partition, and use the sum of the row delay and column delay as the total delay. The actual delay is obtained by taking the modulo of the total delay with the frame period of the display frame. The frame start time of the current display frame plus the actual delay amount is taken as the frame start delay time of the current backlight partition, and the illumination control of the first time period, the second time period and the third time period are executed in sequence.

9. A display panel, characterized in that, The display panel includes: A backlight module is disposed on the back of the display panel body. The backlight module includes multiple backlight zones. Each backlight zone is equipped with red light-emitting diodes, green light-emitting diodes, and blue light-emitting diodes that are independently controlled to turn on and off, as well as a backlight control circuit for driving the red light-emitting diodes, green light-emitting diodes, and blue light-emitting diodes. A backlight control device, connected to the backlight control circuit, is configured to perform the backlight control method according to any one of claims 1 to 8.

10. The display panel according to claim 9, characterized in that, The backlight control circuit includes: The first transistor has its control terminal connected to the main control terminal of the backlight control device. The first terminal of the first transistor is connected to the cathode of the red light-emitting diode, the cathode of the green light-emitting diode, and the cathode of the blue light-emitting diode, respectively. The second terminal of the first transistor is grounded. The second transistor has its control terminal connected to the first sub-control terminal of the backlight control device, its first terminal connected to the cathode of the red light-emitting diode, and its second terminal grounded. The third transistor has its control terminal connected to the second sub-control terminal of the backlight control device, its first terminal connected to the cathode of the green light-emitting diode, and its second terminal grounded. The fourth transistor has its control terminal connected to the third sub-control terminal of the backlight control device, its first terminal connected to the cathode of the blue light-emitting diode, and its second terminal grounded.

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