Display device and its driving method

Abstract

The present invention discloses a display device and a driving method thereof. The display device includes: a display panel, a first data storage unit, a correction coefficient acquisition unit, and a compensation unit. The display panel includes a plurality of sub-pixels. The first data storage unit is used to store gray-scale compensation data. The correction coefficient acquisition unit obtains a correction coefficient according to a first slope and a second slope. The first slope is the slope of the curve of gray scale versus voltage at the current display brightness, and the second slope is the slope of the curve of gray scale versus voltage at the basic display brightness. The compensation unit obtains an actual gray-scale compensation value according to the gray-scale compensation data and the correction coefficient to perform gray-scale compensation on the display screen of the display panel. The present invention can enhance the optical compensation ability in the DC dimming mode and solve the poor visual effect caused by uneven display in the DC dimming mode.

Description

Technical Field

[0001] The present invention relates to the field of display technologies, and more particularly, to a display device and a driving method thereof. Background Art

[0002] With the development of electronic technologies, the manufacturing of display panels has become more and more mature. The display panels provided by the prior art include liquid crystal display panels, organic light-emitting display panels, plasma display panels, etc. As a current-driven light-emitting device, organic light-emitting diodes have been increasingly applied to high-performance displays. OLED display panels have many excellent characteristics such as self-luminescence, wide viewing angle, fast response speed, high contrast ratio, wide color gamut, low energy consumption, thin panel, rich colors, flexible display, and wide working temperature range. Therefore, it is known as the next-generation "star" flat panel display technology. An OLED display panel includes an anode and a cathode, as well as a hole transport layer, an organic light-emitting layer, and an electron transport layer disposed between the anode and the cathode. The anode provides hole injection, and the cathode provides electron injection. Under the drive of an external voltage, the holes and electrons injected from the cathode and the anode recombine in the organic light-emitting layer to form electron-hole pairs (i.e., excitons) in bound energy levels. The excitons radiatively de-excite to emit photons, generating visible light.

[0003] Mura refers to the phenomenon of non-uniform brightness within the display panel, causing various traces. The reason for Mura is that due to reasons such as the manufacturing of sub-pixel materials within the display panel, when the same voltage is provided to the sub-pixels, different currents are generated, manifested as differences in the brightness of different sub-pixels. The greater the difference, the more serious the Mura, and the smaller the difference, the smaller the Mura.

[0004] Currently, there are two dimming modes for display panels. One is the PWM mode, and the other is the DC mode. The principle of the DC mode is to control the display brightness by adjusting the voltage or current of the display panel and changing the power. The PWM mode, without changing the power, controls the display panel to alternately flash at a certain frequency and utilizes the visual persistence effect of the human eye to achieve the effect of continuous display. Simply put, in the DC mode, the display panel is in a lit state throughout one frame time, while in the PWM mode, it is constantly alternating between bright, off, bright, off within one frame time, and the screen brightness is changed by changing the alternating time.

[0005] In the PWM mode, Mura can be significantly improved. However, in the DC mode, the Mura compensation ability is poor, and the Demura compensation is not good at low brightness.

[0006] Therefore, there is an urgent need to provide a display device and a driving method thereof that can enhance the optical compensation ability in the DC dimming mode and solve the poor visual effect caused by uneven display in the DC dimming mode. Summary of the Invention

[0007] In view of this, the present invention provides a display device and a driving method thereof, which are used to enhance the optical compensation ability in the DC dimming mode and solve the poor visual effect caused by uneven display in the DC dimming mode.

[0008] On the one hand, the present invention provides a display device, including:

[0009] A display panel, including a plurality of sub-pixels;

[0010] A first data storage unit, used to store gray-scale compensation data;

[0011] A correction coefficient acquisition unit, obtaining a correction coefficient according to a first slope and a second slope, where the first slope is the slope of the curve of gray scale and voltage at the current display brightness, and the second slope is the slope of the curve of gray scale and voltage at the basic display brightness;

[0012] A compensation unit, obtaining an actual gray-scale compensation value according to the gray-scale compensation data and the correction coefficient, and performing gray-scale compensation on the display picture of the display panel.

[0013] On the other hand, the present invention also provides a driving method of a display device, including:

[0014] Light up the display panel;

[0015] Obtain the current display image of the display panel, and obtain the gray-scale values of each sub-pixel in the current display image;

[0016] According to the current display brightness of the current display image, obtain gray-scale compensation data;

[0017] Obtain a correction coefficient according to a first slope and a second slope, where the first slope is the slope of the curve of gray scale and voltage at the current display brightness, and the second slope is the slope of the curve of gray scale and voltage at the basic display brightness;

[0018] Obtain an actual gray-scale compensation value according to the gray-scale compensation data and the correction coefficient, and perform gray-scale compensation on the display picture of the display panel;

[0019] Obtain the actual gray-scale value of the current display picture according to the gray-scale value and the actual gray-scale compensation value of the current display image.

[0020] Compared with the prior art, the display device and the driving method thereof provided by the present invention at least achieve the following beneficial effects:

[0021] When the display panel of the display device of the present invention displays a display screen, according to the current display brightness of the current display image, gray-scale compensation data is obtained, and a first slope and a second slope are determined. The first slope is the slope of the curve of gray-scale versus voltage at the current display brightness, and the second slope is the slope of the curve of gray-scale versus voltage at the basic display brightness. A correction coefficient is obtained based on the first slope and the second slope, and finally, an actual gray-scale compensation value is obtained based on the gray-scale compensation data and the correction coefficient, so as to perform gray-scale compensation on the display screen of the display panel. According to the gray-scale value of the current display image and the actual gray-scale compensation value, the actual gray-scale value of the current display screen is obtained. In the present invention, a correction coefficient is added during gray-scale compensation. The correction coefficient is a correction coefficient determined by the relationship between voltage changes when gray-scale changes at the current display brightness and the basic display brightness. This correction coefficient can amplify the multiple of gray-scale compensation, thereby enhancing the optical compensation ability in the DC dimming mode and solving the problem of poor visual effects caused by uneven display in the DC dimming mode.

[0022] Of course, any product implementing the present invention does not necessarily need to achieve all the above-mentioned technical effects simultaneously.

[0023] Other features and advantages of the present invention will become clear from the following detailed description of the exemplary embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings incorporated in and constituting a part of this specification illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0025] Figure 1 is a corresponding relationship diagram of gray-scale and voltage in the PWM mode and the DC mode when the brightness is 2 nit in the related art;

[0026] Figure 2 is a schematic plan view of a display device provided by the present invention;

[0027] Figure 3 is a pixel circuit provided by the present invention;

[0028] Figure 4 is a timing diagram provided by the present invention;

[0029] Figure 5 is a schematic plan view of another display device provided by the present invention;

[0030] Figure 6 is a schematic plan view of another display device provided by the present invention;

[0031] Figure 7 is a flowchart of a driving method of a display device provided by the present invention;

[0032] Figure 8 It is a flowchart of a driving method for another display device provided by the present invention;

[0033] Figure 9 It is a flowchart of a method for calculating grayscale compensation data provided by the present invention. Detailed Description of the Invention

[0034] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention.

[0035] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way a limitation on the present invention or its application or use.

[0036] Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be regarded as part of the specification.

[0037] In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments may have different values.

[0038] It should be noted that: similar reference numerals and letters denote similar items in the following drawings, and thus, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0039] In view of the fact that the Mura compensation ability of a display device in the related art is poor in the DC mode, and there is a problem that the Demura compensation is not good at low brightness, the inventor has studied the related art. Referring to Figure 1 , Figure 1 is a diagram showing the correspondence between grayscale and voltage in the PWM mode and the DC mode when the brightness is 2 nit in the related art. The abscissa is the grayscale, and the ordinate is the source voltage, that is, the data voltage. The data voltage determines the brightness of the sub-pixels on the corresponding data line. 2 nit is the state when the display device is in a low-brightness state. For the PWM mode, the display device is constantly alternating between bright, off, bright, and off, while the DC mode screen is always in a bright state. The DC mode has a long luminous time. At the same brightness, the driving transistor current is smaller, and the screen Mura is serious. Therefore, a greater Demura compensation ability is required. Combining Figure 1 , in the related art, the compensation offset is stored in the form of grayscale. From Figure 1It can be seen that since the gray-scale and voltage relationship curve in the PWM mode is steeper than that in the DC mode, that is, the slope of the gray-scale and voltage relationship in the PWM mode is greater than the slope of the gray-scale and voltage relationship curve in the DC mode. Of course, the gray-scale and voltage relationship curve is related to the light-emitting material in the display panel. When the light-emitting material is fixed, the gray-scale and voltage relationship curve is also determined. Therefore, the voltage change corresponding to a gray-scale change in the PWM mode is greater than the voltage change corresponding to a gray-scale change in the DC mode. Figure 1 In the PWM mode, the voltage change corresponding to a gray-scale change is twice that in the DC mode. Therefore, when performing compensation, the multiple by which the compensation offset needs to be amplified in the DC mode is much larger than that in the PWM mode in order for the ordinate data signal to be compensated to an appropriate voltage. The maximum amplification value supported by the driving chip in the related art is 4 times, which will exceed the maximum value supported by the existing driving chip. Therefore, in low brightness, the low-brightness Demura compensation in the DC mode is not good.

[0040] In view of this, the present invention provides a display device and its driving method, which solve the problem of poor visual effect caused by uneven display in the DC dimming mode. The specific embodiments of the display device and its driving method will be described in detail below.

[0041] Refer to Figure 2 、 Figure 3 and Figure 4 , Figure 2 is a schematic plan view of a display device provided by the present invention. Figure 3 is a pixel circuit provided by the present invention. Figure 4 is a timing diagram provided by the present invention. As Figure 2 The display device 100 includes: a display panel 10 including a plurality of sub-pixels P; a first data storage unit 20 for storing gray-scale compensation data; a correction coefficient acquisition unit 30 for obtaining a correction coefficient according to a first slope and a second slope, where the first slope is the slope of the gray-scale and voltage curve at the current display brightness, and the second slope is the slope of the gray-scale and voltage curve at the basic display brightness; a compensation unit 40 for obtaining an actual gray-scale compensation value according to the gray-scale compensation data and the correction coefficient to perform gray-scale compensation on the display screen of the display panel 10.

[0042] Specifically, the display panel 10 can be an organic light-emitting display panel. In the present invention, the display device 100 can effectively compensate for uneven display in the low-brightness state. The low-brightness state means that the average brightness of the display panel 10 is between 2 nit and 110 nit, or the average brightness of the display panel 10 is between 2 nit and 90 nit. Here, the average brightness value of the low brightness is not specifically limited.

[0043] Figure 2 It is shown that the display panel 10 further includes a non-display area BB surrounding the display area AA. Figure 2 Only the rectangular display panel 10 is taken as an example to illustrate the display panel 10. In some other embodiments of the present application, the display panel 10 may also be embodied in other shapes, such as circular, oval or irregular shapes, etc. Figure 2 Only the case where the non-display area BB completely surrounds the display area AA is shown. Of course, the non-display area BB may also semi-surround the display area AA (such as a water-drop screen), which is not specifically limited here. Figure 2 Only some of the sub-pixels P in the display area AA are respectively shown, which does not represent the actual number and arrangement of the sub-pixels P included in the display area AA. Additionally Figure 2 It also does not represent the actual size of the sub-pixel P, but is only for illustration.

[0044] In this embodiment, a first non-display area BB1 and a second non-display area BB2 are also shown. The first shift register 21 is located in the first non-display area BB1, that is, the first shift register 21 is single-sided driven. Such a setting can reduce the width of the first non-display area BB1 in the first direction X to achieve a narrow border. The first shift register 21 provides a light-emitting control signal Emit for the pixel circuit 000, that is, the signal for controlling whether the first transistor M1 and the fifth transistor M5 are turned on. Similarly, the second shift register 22 is located in the second non-display area BB2, that is, the second shift register 22 is single-sided driven. Such a setting can reduce the width of the second non-display area BB2 in the first direction X to achieve a narrow border. The second shift register 22 provides a first control signal S1 for the pixel circuit 000. The positions of the first shift register 21 and the second shift register 22 are not specifically limited, as long as the first shift register 21 and the second shift register 22 are located on opposite sides of the non-display area BB. For example, the first shift register 21 is located on the left border and the second shift register 22 is located on the right border, or the first shift register 21 is located on the right border and the second shift register 22 is located on the left border. Figure 2 A third shift register 23 is also shown. The third shift register 23 is located in both the first non-display area BB1 and the second non-display area BB2 at the same time, that is, the third shift register 23 is double-sided driven. The third shift register 23 can provide a second control signal S2 for the pixel circuit 000.

[0045] As Figure 3As shown, the pixel driving circuit 000 includes: a first transistor M1, whose control terminal is electrically connected to the light-emitting signal input terminal, the first terminal is electrically connected to the first power supply signal terminal VDD, the second terminal is electrically connected to the first terminal of the driving transistor M, and the first power supply signal terminal VDD inputs a first power supply voltage PVDD; a second transistor M2, whose control terminal is electrically connected to the second scan signal input terminal S2, the first terminal is electrically connected to the data signal input terminal data, and the second terminal is electrically connected to the first terminal of the driving transistor M; a driving transistor M, whose control terminal is electrically connected to the second terminal of the fourth transistor M4, and the first terminal is electrically connected to the second terminal of the first transistor M1 and the second terminal of the second transistor M2; a third transistor M3, whose control terminal is electrically connected to the second scan signal input terminal S2, the first terminal is electrically connected to the second terminal of the fourth transistor M4 and the second terminal of the storage capacitor Cst, and the second terminal is electrically connected to the second terminal of the driving transistor M and the first terminal of the fifth transistor M5; a fourth transistor M4, whose control terminal is electrically connected to the first scan signal input terminal S1, the first terminal is electrically connected to the reference voltage signal input terminal Vref, and the second terminal is electrically connected to the control terminal of the driving transistor M; a fifth transistor M5, whose control terminal is electrically connected to the light-emitting signal input terminal Em, the first terminal is electrically connected to the second terminal of the driving transistor M and the second terminal of the third transistor M3, and the second terminal is electrically connected to the anode of the light-emitting element O; a sixth transistor M6, whose control terminal is electrically connected to the second scan signal input terminal, the first terminal is electrically connected to the reference voltage signal input terminal, and the second terminal is electrically connected to the first terminal of the light-emitting element O; a light-emitting element O, whose first terminal is electrically connected to the second terminal of the fifth transistor M5 and the second terminal of the sixth transistor M6, and the second terminal is electrically connected to the second power supply signal terminal VEE, and the second power supply signal terminal VEE inputs a second power supply voltage PVEE; a storage capacitor Cst, whose first terminal is electrically connected to the first power supply signal terminal VDD, and the second terminal is electrically connected to the control terminal of the driving transistor M, the first terminal of the third transistor M3, and the second terminal of the fourth transistor M4.

[0046] As Figure 4As shown, the driving timing of the pixel circuit includes a reset stage t1, a data writing stage t2, and a light emitting stage t3. In the reset stage t1, the fourth transistor M4 and the sixth transistor M6 are turned on, and the reset signal Vref is written into the first node N1 and the anode of the light emitting element O respectively to reset the first node N1. The driving transistor M is turned on in response to the potential of the first node N1, and the reset signal Vref is written into the anode of the light emitting element O to reset the anode of the light emitting element O. In the data writing stage t2, the second transistor M2 is turned on, and at the same time, the third transistor M3 is turned on, and the data signal Vdata is written into the first node N1 through the driving transistor M. In the light emitting stage t3, the first transistor M1 and the fifth transistor M5 are turned on under the control of the light emitting control signal Emit, and the light emitting element O emits light when a current is formed between the first power signal terminal VDD and the second power signal terminal VEE. It can be seen that the light emitting time in the light emitting stage is determined by the light emitting control signal Emit. In the DC mode, the light emitting control signal Emit remains at a low potential to ensure that the first transistor M1 and the fifth transistor M5 remain turned on.

[0047] The first data storage unit 20 of the present invention is used to store the gamma compensation data. It can be understood that compensation can be performed through Demura, and the brightness of the pixel points can be corrected by means of gamma compensation, thereby improving the Mura phenomenon. Gamma compensation improves the brightness uniformity by changing the gamma value of the pixel. The process of Demura is to capture the Mura condition of the gamma image through a camera. When the input image is a single gamma image, according to the brightness of the center area of the panel, some algorithms are used to extract and correct the Mura, so as to increase a certain gamma compensation value for the pixels in the darker area and reduce a certain gamma compensation value for the pixels in the brighter area, realizing the improvement of the Mura phenomenon. The compensation values (or Demura data) for all pixels can be made into a Demura table for hardware processing, that is, the gamma compensation data is stored in the first data storage unit 20 and called during subsequent compensation.

[0048] The relationship curve between gamma and voltage is stored in the correction coefficient acquisition unit 30. When the light emitting material in the display panel 10 is determined, the relationship curve between gamma and voltage is determined, and then the slope of the relationship curve between gamma and voltage can be determined. The correction coefficient acquisition unit 30 needs to obtain the first slope and the second slope, and then calculate the correction coefficient according to the first slope and the second slope. In the present invention, the first slope is the slope of the curve between gamma and voltage at the current display brightness, and the second slope is the slope of the curve between gamma and voltage at the basic display brightness. The basic display brightness in the present invention refers to based on one determined display brightness, and by comparing the current display brightness with the basic display brightness, the magnification of compensation can be determined, that is, the correction coefficient.

[0049] The compensation unit 40 is respectively coupled to the first data storage unit 20 and the correction coefficient acquisition unit 30, and performs gray-scale compensation on the display screen of the display panel 10 according to the gray-scale compensation data and the correction coefficient. After the gray-scale compensation data is obtained from the first data storage unit 20 and the correction coefficient is obtained from the correction coefficient acquisition unit 30, the actual gray-scale compensation value can be obtained, and thus the display screen of the display panel 10 is gray-scale compensated.

[0050] In the present invention, a correction coefficient is added during gray-scale compensation. The correction coefficient is a correction coefficient determined by the relationship between the voltage change and the gray-scale change under the current display brightness and the basic display brightness. This correction coefficient can amplify the multiple of gray-scale compensation, thereby enhancing the optical compensation ability in the DC dimming mode and solving the problem of poor visual effect caused by uneven display in the DC dimming mode.

[0051] In some alternative embodiments, continue to refer to Figure 2 , the correction coefficient acquisition unit 30 obtaining the correction coefficient according to the first slope and the second slope includes: α = α1 / α2, where α is the correction coefficient, α1 is the first slope, and α2 is the second slope.

[0052] Specifically, when the display panel 10 is displaying, even if the display screen is the same, but if the brightness bar is slid, the brightness of the display screen changes with the change of the brightness bar. A brightness bar band of the display panel 10 will generate a set of gray-scale and brightness relationship curves. The brightness corresponding to the gray scale is different under different brightness bar bands, that is, the voltage of the data signal Vdata corresponding to the same gray scale is different under different brightness bar bands. The first slope α1 is the curve slope of the gray scale and the voltage under the current display brightness, and the second slope α2 is the curve slope of the gray scale and the voltage under the basic display brightness. The ratio of the first slope α1 to the second slope α2 converts the current display brightness into the relationship between the gray scale and the voltage under the basic display brightness, and performs compensation under the same basic display brightness, amplifying the multiple of gray-scale compensation.

[0053] In some alternative embodiments, continue to refer to Figure 2 , the compensation unit 40 performs gray-scale compensation on the display screen of the display panel 10 according to the gray-scale compensation data and the correction coefficient. Specifically, the compensation unit 40 calculates the actual gray-scale compensation value offset_out according to offset_out = offset × Gain × α, where the gray-scale compensation data includes the compensation value offset and the correction coefficient Gain, and α is the correction coefficient.

[0054] The grayscale compensation data such as the compensation value offset and the correction coefficient Gain are all stored in the first data storage unit 20. In the related art, the actual grayscale compensation value offset_out is only equal to the product of the compensation coefficient offset and the correction coefficient Gain, and does not adjust the voltage change according to the grayscale. In the present invention, the actual grayscale compensation value offset_out is equal to the product of the compensation coefficient offset, the correction coefficient Gain, and the correction coefficient α, and this correction coefficient can amplify the multiple of the grayscale compensation, thereby improving the optical compensation ability in the DC dimming mode.

[0055] In some alternative embodiments, with continued reference to Figure 2 , the actual displayed grayscale of the display screen of the display panel 10 is equal to the sum of the grayscale value of the current display screen and the actual grayscale compensation value.

[0056] The actual grayscale compensation value offset_out = offset × Gain × α, and the actual displayed grayscale Grey_out of the display screen = Grey_Now + offset_out = Grey_Now + offset × Gain × α.

[0057] Specifically, the brightness of each sub-pixel at different grayscales is captured, and the compensation coefficient of each sub-pixel of the display panel 10 at a certain grayscale (such as 64 grayscales or 32 grayscales) can be calculated through the brightness data of each sub-pixel at different grayscales. This compensation coefficient can be positive or negative. When each sub-pixel on the display panel 10 displays the brightness of 0 - 255 grayscales, the corresponding compensation coefficient calculated for each sub-pixel is superimposed on each sub-pixel respectively. For example, the compensation coefficient of a certain red sub-pixel is -7 grayscales. If this red sub-pixel needs to display 7 grayscales according to the image, and the correction coefficient Gain set for 7 grayscales is 1, and the correction coefficient calculated according to the first slope and the second slope is 2, then the actually displayed is 7 + (-7×1×2) = -7 grayscales of red; similarly, if this sub-pixel needs to display 64 grayscales of red according to the image, and the correction coefficient Gain set for 64 grayscales is 0.5, and the correction coefficient calculated according to the first slope and the second slope is 2, then the actually displayed is 64 + (-7×0.5×2) = 57 grayscales of red brightness.

[0058] In the present invention, a correction coefficient is added during grayscale compensation. This correction coefficient is a correction coefficient determined by the relationship between the voltage change when the grayscale changes under the current display brightness and the basic display brightness. This correction coefficient can amplify the multiple of the grayscale compensation, thereby enhancing the optical compensation ability in the DC dimming mode and solving the problem of poor visual effect caused by uneven display in the DC dimming mode.

[0059] In some alternative embodiments, with reference to Figure 5 , Figure 5It is a schematic plan view of another display device provided by the present invention, and further includes a display driving chip IC. The display driving chip IC includes a look-up table, and correction coefficients are stored in the look-up table.

[0060] Optionally, the display driving chip IC is reused as a correction coefficient acquisition unit 30, and the correction coefficients are stored in the look-up table of the display driving chip IC. That is, the correction coefficients corresponding to different brightness bands can be calculated and burned into the look-up table of the display driving chip IC after Gamma debugging. When gray-scale compensation is to be performed, they can be directly retrieved from the display driving chip IC, enabling rapid compensation and improving compensation efficiency.

[0061] In some alternative embodiments, referring to Figure 6 , Figure 6 It is a schematic plan view of another display device provided by the present invention, and further includes a flash memory chip 50 and a display driving chip IC. The first data storage unit 20 is reused as the flash memory chip 50. The flash memory chip 50 is electrically connected to the display driving chip IC, and the display driving chip IC retrieves gray-scale compensation data.

[0062] Optionally, a flash memory chip 50 is provided in the display device 100, and gray-scale compensation data such as compensation coefficients offset and correction coefficients Gain are burned into the flash memory chip 50. When gray-scale compensation is to be performed, the gray-scale compensation data is read from the flash memory chip 50, enabling rapid compensation and improving compensation efficiency.

[0063] Based on the same inventive concept, the present invention further provides a driving method for a display device, which is applied to the above display device 100. The driving method of the display device 100 refers to Figure 7 , Figure 7 It is a flow chart of a driving method for a display device provided by the present invention. As shown in Figure 7 , it includes the following steps:

[0064] S1: Light up the display panel;

[0065] S2: Obtain the current display image of the display panel to obtain the gray-scale values of each sub-pixel in the current display image;

[0066] S3: Obtain gray-scale compensation data according to the current display brightness of the current display image;

[0067] S4: Obtain a correction coefficient according to a first slope and a second slope. The first slope is the slope of the curve of gray scale versus voltage at the current display brightness, and the second slope is the slope of the curve of gray scale versus voltage at the basic display brightness;

[0068] S5: Obtain an actual gray-scale compensation value according to the gray-scale compensation data and the correction coefficient, and perform gray-scale compensation on the display screen of the display panel;

[0069] S6: Obtain the actual gray level value of the current display screen according to the gray level value of the current display image and the actual gray level compensation value.

[0070] In the driving method of the present invention, first light up the display panel, and obtain the gray level values of each sub-pixel in the current display image according to the image to be displayed on the display panel. The gray level values of each sub-pixel in the current display image can be obtained, and of course, the brightness bar of the current image can be obtained; according to the current display brightness of the current display image, obtain gray level compensation data. Here, the gray level compensation data includes the compensation value offset and the correction coefficient gain; then it is necessary to obtain the correction coefficient of the current display image. Here, the correction coefficient is obtained according to the first slope and the second slope. The first slope is the curve slope of the gray level and voltage at the current display brightness, and the second slope is the curve slope of the gray level and voltage at the basic display brightness. In the related art, only the compensation value offset and the correction coefficient Gain are used for gray level compensation, while in the present invention, a correction coefficient is added during gray level compensation. The correction coefficient is a correction coefficient determined by the voltage change relationship when the gray level changes at the current display brightness and the basic display brightness. The correction coefficient can amplify the multiple of gray level compensation, so as to enhance the optical compensation ability in the DC dimming mode and solve the problem of poor visual effect caused by uneven display in the DC dimming mode.

[0071] In some alternative embodiments, refer to Figure 8 , Figure 8 is a flowchart of a driving method for another display device provided by the present invention. Obtaining the actual gray level value of the current display screen according to the gray level value of the current display image and the actual gray level compensation value includes:

[0072] Grey_out = Grey_Now + offset_out,

[0073] where Grey_out is the actual gray level value of the current display screen, Grey_Now is the gray level value of the current display image, and offset_out is the actual gray level compensation value.

[0074] Specifically, the brightness of each sub-pixel at different gray levels is captured. Based on the brightness data of each sub-pixel at different gray levels, the compensation coefficient of each sub-pixel on the display panel at a certain gray level (such as 64 gray levels or 32 gray levels) can be calculated. This compensation coefficient can be positive or negative. When each sub-pixel on the display panel displays brightness at 0 - 255 gray levels, the corresponding compensation coefficient calculated for each sub-pixel is superimposed on each sub-pixel respectively. For example, if the red sub-pixel is required to display 7 gray levels according to the image, and the actual gray level compensation value offset_out calculated is -14, then the actual displayed gray level is 7 + (-14) = -7 levels of red; similarly, if this sub-pixel is required to display 64 levels of red according to the image, and the actual gray level compensation value offset_out calculated is -7, then the actual displayed brightness is 64 + (-7) = 57 levels of red.

[0075] The actual displayed gray level of the display screen of the display panel of the present invention is equal to the sum of the gray level value of the current display screen and the actual gray level compensation value, compensating the gray level of the current display screen, and improving the problem of poor visual effect caused by uneven display.

[0076] In some optional embodiments, continue to refer to Figure 8 , and the actual gray level compensation value offset_out is calculated by the following method:

[0077] offset_out = offset × Gain × α,

[0078] wherein, the gray level compensation data includes the compensation value offset and the correction coefficient Gain, and α is the correction coefficient.

[0079] In the related art, the actual gray level compensation value offset_out is only equal to the product of the compensation coefficient offset and the correction coefficient Gain, and does not adjust the voltage change according to the gray level. In the present invention, the actual gray level compensation value offset_out is equal to the product of the compensation coefficient offset, the correction coefficient Gain, and the correction coefficient α. This correction coefficient can amplify the multiple of the gray level compensation, thereby improving the optical compensation ability in the DC dimming mode.

[0080] In some optional embodiments, continue to refer to Figure 1 and Figure 8 , and the display driving chip IC stores the relationship curve between the gray level and the voltage at different display brightnesses, with the horizontal coordinate being the gray level and the vertical coordinate being the voltage.

[0081] It can be understood that the display driving chip IC usually stores the relationship curve between the gray level and the voltage at different display brightnesses. Figure 1Taking the curve of the relationship between gray level and voltage at a brightness of 2 nits as an example, when the light-emitting material is fixed, the curve of the relationship between gray level and voltage is determined. The curves of the relationship between gray level and voltage at different display brightness levels are stored in the display driver chip IC and can be retrieved from the display driver chip IC at any time during gray level compensation, which can improve the efficiency of gray level compensation.

[0082] In some alternative embodiments, with continued reference to Figure 1 and Figure 8 , obtaining the correction coefficient according to the first slope and the second slope includes: α = α1 / α2, where α is the correction coefficient, α1 is the first slope, and α2 is the second slope;

[0083] The first slope α1 and the second slope α2 are obtained according to the following method:

[0084] α1 = (Grey_Low_V_Base - Grey_High_V_Base) / (Grey_High - Grey_Low), α2 = (Grey_Low_V_Now - Grey_High_V_Now) / (Grey_High - Grey_Low),

[0085] where Grey_High is the first gray level, Grey_Low is the second gray level, the first gray level is greater than the second gray level, Grey_Low_V_Base is the voltage corresponding to the first gray level in the basic display brightness, Grey_High_V_Base is the voltage corresponding to the second gray level in the basic display brightness; Grey_Low_V_Now is the voltage corresponding to the first gray level in the current display brightness, and Grey_High_V_Now is the voltage corresponding to the second gray level in the current display brightness.

[0086] It should be noted that when taking the slope of the curve of the relationship between gray level and voltage, the abscissa cannot take the region where the slope suddenly increases. For example, Figure 1 when the gray level is less than 7 in

[0087] the voltage suddenly increases, so the gray level value for calculating the slope is taken in the region where the gray level is greater than 7.

[0088] In some alternative embodiments, with reference to Figure 9 Figure 9 is a flowchart of a method for calculating gray level compensation data provided by the present invention. As shown in Figure 9The grayscale compensation data shown is obtained according to the following method:

[0089] S201, set the average brightness value of the display panel;

[0090] S202, take a picture to obtain the brightness data of each sub-pixel of the current display brightness of the display panel at multiple test grayscales;

[0091] S203, calculate the compensation coefficient of each sub-pixel of the display panel at the specified grayscale of the basic display brightness through the brightness data of each sub-pixel at different levels;

[0092] S204, burn the compensation coefficient into the flash memory chip 50.

[0093] Specifically, in step S201: set the average brightness value of the display image. Here, the average brightness value of the display image is to select one of the display brightnesses. For example, the display image with an average brightness of 32 nit can be selected as the basis, and the display images corresponding to other brightnesses can be calculated according to the method of linear interpolation. Here, there is no specific limitation on the average brightness value of the set display image. Optionally, it can be 2 nit, 10 nit, 26 nit, 135 nit, etc.

[0094] Step S202: Obtain the brightness of each sub-pixel in the display image, calculate the brightness difference between the brightness of each sub-pixel and the average brightness value, and convert the brightness difference into a grayscale difference. Further, obtain the brightness of each sub-pixel. For example, the brightness of the sub-pixel is 19 nit, 20 nit, 19 nit, 23 nit, 28 nit, 26 nit, 26 nit, 26 nit, 30 nit... etc., and the set average brightness value is 26 nit. Then the brightness differences are 7 nit, 6 nit, 7 nit, 3 nit, 2 nit, 0, 0, 0, 4 nit... respectively. Convert the brightness differences into grayscale differences, such as 7, 6, 7, 3, 2, 0, 0, 0, -4... etc. Of course, this is only for illustrative purposes and is not a limitation for actual products.

[0095] Step S203: Calculate the compensation coefficient of each sub-pixel of the display panel at the specified grayscale of the basic display brightness through the brightness data of each sub-pixel at different levels. For example, the grayscale differences are 7, 6, 7, 3, 2, 0, 0, 0, -4... etc.

[0096] In step S204, burn the compensation coefficient into the flash memory chip 50. In this way, when performing grayscale compensation, it can be directly read from the flash memory chip 50, which improves the grayscale compensation efficiency of the display panel. Moreover, there is no need to burn the compensation coefficient into the display driver chip IC, which can reduce the amount of data stored in the display driver chip IC and improve the working efficiency of the display driver chip IC.

[0097] In some alternative embodiments, with continued reference to Figure 5 , the correction coefficient is burned into the display driver chip IC, or the display driver chip IC calculates the correction coefficient in real time.

[0098] Optionally, the correction coefficient is stored in the display driver chip IC. First, a lookup table is established in the display driver chip IC, and the correction coefficient is stored in the lookup table. That is, the correction coefficients corresponding to different brightness bands can be calculated after Gamma debugging and burned into the lookup table of the display driver chip IC. When grayscale compensation is to be performed, it can be directly retrieved from the display driver chip IC, enabling fast compensation and improving the compensation efficiency.

[0099] Optionally, the display driver chip IC can also calculate the correction coefficient in real time, which is not shown in the figure. In this way, there is no need to store a large amount of correction coefficient data in the display driver chip IC. The correction coefficient is calculated in real time during grayscale compensation, which can reduce the amount of data stored in the display driver chip IC and improve the working efficiency of the display driver chip IC.

[0100] As can be seen from the above embodiments, the display device and its driving method provided by the present invention at least achieve the following beneficial effects:

[0101] When the display panel of the display device of the present invention displays a picture, grayscale compensation data is obtained according to the current display brightness of the current display image, and the first slope and the second slope are determined. The first slope is the slope of the curve of grayscale versus voltage at the current display brightness, and the second slope is the slope of the curve of grayscale versus voltage at the basic display brightness. The correction coefficient is obtained based on the first slope and the second slope. Finally, the actual grayscale compensation value is obtained based on the grayscale compensation data and the correction coefficient, and the display picture of the display panel is grayscale compensated accordingly. The actual grayscale value of the current display picture is obtained based on the grayscale value of the current display image and the actual grayscale compensation value. In the present invention, a correction coefficient is added during grayscale compensation. This correction coefficient is a correction coefficient determined by the relationship between the voltage change and the grayscale change at the current display brightness and the basic display brightness. This correction coefficient can amplify the multiple of grayscale compensation, thereby enhancing the optical compensation ability in the DC dimming mode and solving the problem of poor visual effects caused by uneven display in the DC dimming mode.

[0102] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present invention. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A display device, characterized in that, comprising: a display panel including a plurality of sub-pixels; a first data storage unit for storing gray-scale compensation data; a correction coefficient acquisition unit for obtaining a correction coefficient based on a first slope and a second slope, where the first slope is the slope of the curve of gray-scale versus voltage at the current display brightness, and the second slope is the slope of the curve of gray-scale versus voltage at a basic display brightness, wherein the basic display brightness is a determined display brightness, and obtaining the correction coefficient based on the first slope and the second slope includes: α = α1 / α2, where α is the correction coefficient, α1 is the first slope, and α2 is the second slope; a compensation unit for obtaining an actual gray-scale compensation value based on the gray-scale compensation data and the correction coefficient to perform gray-scale compensation on the display screen of the display panel, which includes: calculating the actual gray-scale compensation value offset_out by the following method: offset_out = offset × Gain × α, wherein the gray-scale compensation data includes a compensation value offset and a correction coefficient Gain, and α is the correction coefficient.

2. The display device according to claim 1, characterized in that, the actual display gray-scale of the display screen of the display panel is equal to the sum of the gray-scale value of the current display screen and the actual gray-scale compensation value.

3. The display device according to claim 1, characterized in that, further comprising a display driver chip, the display driver chip includes a look-up table, and the correction coefficient is stored in the look-up table.

4. The display device according to claim 1, characterized in that, further comprising a flash memory chip and a display driver chip, the first data storage unit is multiplexed as the flash memory chip, the flash memory chip is electrically connected to the display driver chip, and the display driver chip retrieves the gray-scale compensation data.

5. A driving method for a display device, characterized in that, comprising: turning on the display panel; acquiring the current display image of the display panel to obtain the gray-scale values of the sub-pixels in the current display image; acquiring gray-scale compensation data according to the current display brightness of the current display image; obtaining a correction coefficient based on a first slope and a second slope, where the first slope is the slope of the curve of gray-scale versus voltage at the current display brightness, and the second slope is the slope of the curve of gray-scale versus voltage at a basic display brightness, wherein the basic display brightness is a determined display brightness, and obtaining the correction coefficient based on the first slope and the second slope includes: α = α1 / α2, where α is the correction coefficient, α1 is the first slope, and α2 is the second slope; obtaining an actual gray-scale compensation value based on the gray-scale compensation data and the correction coefficient to perform gray-scale compensation on the display screen of the display panel, which includes: calculating the actual gray-scale compensation value offset_out by the following method: offset_out = offset × Gain × α, where the gray-scale compensation data includes a compensation value offset and a correction coefficient Gain, and α is the correction coefficient; obtaining the actual gray-scale value of the current display screen based on the gray-scale value of the current display image and the actual gray-scale compensation value.

6. The driving method of the display device according to claim 5, characterized in that, obtaining the actual gray level value of the current display screen according to the gray level value of the current display image and the actual gray level compensation value includes: Grey_out = Grey_Now + offset_out, where Grey_out is the actual gray level value of the current display screen, Grey_Now is the gray level value of the current display image, and offset_out is the actual gray level compensation value.

7. The driving method of the display device according to claim 5, characterized in that, in the display driving chip, a curve of the relationship between gray level and voltage at different display brightness levels is stored, with the horizontal coordinate being the gray level and the vertical coordinate being the voltage.

8. The driving method of the display device according to claim 7, characterized in that, the first slope α1 and the second slope α2 are obtained according to the following method: α1 = (Grey_Low_V_Base - Grey_High_V_Base) / (Grey_High - Grey_Low), α2 = (Grey_Low_V_Now - Grey_High_V_Now) / (Grey_High - Grey_Low), where Grey_High is the first gray level, Grey_Low is the second gray level, the first gray level is greater than the second gray level, Grey_Low_V_Base is the voltage corresponding to the first gray level in the basic display brightness, Grey_High_V_Base is the voltage corresponding to the second gray level in the basic display brightness; Grey_Low_V_Now is the voltage corresponding to the first gray level in the current display brightness, Grey_High_V_Now is the voltage corresponding to the second gray level in the current display brightness.

9. The driving method of the display device according to claim 5, characterized in that, the gray level compensation data is obtained according to the following method: setting an average brightness value of the display panel; taking a picture to obtain the brightness data of each sub-pixel of the current display brightness of the display panel at multiple test gray levels; calculating the compensation coefficient of each sub-pixel of the display panel at the specified gray level of the basic display brightness through the brightness data of each sub-pixel at different levels; burning the compensation coefficient into the flash memory chip.

10. The driving method of the display device according to claim 5, characterized in that, the correction coefficient is burned in the display driving chip, or the display driving chip calculates the correction coefficient in real time.

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