CN115641814B - Display device and driving method thereof - Google Patents
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Abstract
The invention discloses a display device and a driving method thereof, wherein the display device comprises a display panel, and the display panel comprises a plurality of sub-pixels; the image processing unit is coupled with the display panel, processes the display image of the display panel and judges the degree of uneven brightness of the display image; and the compensation unit is coupled with the image processing unit, and is used for calling the corresponding parameter values of different luminous control signal duty ratios according to the uneven brightness degree of the display image so as to carry out brightness compensation on the display image. According to the invention, the parameter values corresponding to the duty ratios of different light-emitting control signals are called according to the severity of uneven brightness cloth of the display image, and brightness compensation is carried out on the display image, so that the uniformity under low brightness can be improved.
Description
Technical Field
The present invention relates to the field of display technologies, and more particularly, to a display device and a driving method thereof.
Background
With the development of electronic technology, the manufacturing of display panels has also tended to mature, and display panels provided in the prior art include liquid crystal display panels, organic light emitting display panels, plasma display panels, and the like. Organic light emitting diodes are increasingly used as a current-type light emitting device in high performance display, and an OLED display panel has excellent characteristics of self-luminescence, wide viewing angle, fast response speed, high contrast, wide color gamut, low energy consumption, thin panel, rich color, flexible display realization, wide operating temperature range and the like, so that the OLED display panel is known as a next-generation 'star' flat panel display technology. The OLED display panel comprises an anode, a cathode, a hole transmission layer, an organic light-emitting layer and an electron transmission layer, wherein the hole transmission layer, the organic light-emitting layer and the electron transmission layer are arranged between the anode and the cathode, the anode provides hole injection, the cathode provides electron injection, the holes and electrons injected by the cathode and the anode are combined in the organic light-emitting layer under the driving of external voltage, electron hole pairs (namely excitons) at a binding energy level are formed, and the excitons radiate and are de-excited to emit photons to generate visible light.
Mura is a phenomenon that brightness in a display panel is uneven, various marks are caused, and the cause of the Mura is that, due to the fact that sub-pixel materials in the display panel are made, when the same voltage is provided for the sub-pixels, different currents are generated, the brightness of different sub-pixels is different, the larger the difference is, the more serious the Mura is, the smaller the difference is, and the smaller the Mura is.
At present, the problem can be solved by performing compensation through Demura, and correcting the brightness of the pixel point through a gray level compensation mode, so as to improve the Mura phenomenon. Gray scale compensation improves brightness uniformity by changing the gray scale of the pixel. The process of Demura is that the Mura condition of gray-scale picture is shot by camera, when the input image is single gray-scale picture, according to the brightness of central area of panel, the Mura is extracted and corrected by some algorithms so as to add a certain gray-scale compensation value to the pixels of dark area and reduce a certain gray-scale compensation value to the pixels of bright area, so that the improvement of Mura phenomenon is realized. The compensation values (or Demura data) for all pixels can be made into a Demura table for processing by hardware.
However, in the prior art, when Mura of the display panel is serious and low in brightness, effective compensation cannot be performed.
Accordingly, there is a need for a display device and a driving method thereof that can effectively compensate for uneven display during low-luminance display.
Disclosure of Invention
In view of the above, the present invention provides a display device and a driving method thereof, which effectively compensates according to the severity of the display panel Mura.
In one aspect, the present invention provides a display device including: a display panel including a plurality of subpixels; the image processing unit is coupled with the display panel, processes the display image of the display panel and judges the degree of uneven brightness of the display image; and the compensation unit is coupled with the image processing unit, and is used for calling the corresponding parameter values of different luminous control signal duty ratios according to the uneven brightness degree of the display image so as to carry out brightness compensation on the display image.
On the other hand, the invention also provides a driving method of the display device, which comprises the steps of acquiring a display image of the display panel;
Judging the degree of uneven brightness of the display image, wherein the degree of uneven brightness comprises a first stage and a second stage, and the first stage is smaller than the second stage;
When the degree of the uneven brightness is judged to be the first level, a first group of parameter values corresponding to a first duty ratio are called, and brightness adjustment is carried out on the display image of the display panel; and when the degree of the uneven brightness is judged to be the second level, invoking a second group of parameter values corresponding to a second duty ratio, wherein the first duty ratio is larger than the second duty ratio, and performing brightness adjustment on the display image of the display panel.
Compared with the prior art, the display device and the driving method thereof provided by the invention have the advantages that at least the following effects are realized:
The display device comprises an image processing unit and a compensation unit, wherein the image processing unit judges the degree of uneven brightness of a display image in a low-brightness state, namely judges the severity of Mura, the compensation unit calls parameter values corresponding to different luminous control signal duty ratios according to the degree of uneven brightness of the display image, brightness compensation is carried out on the display image, if the Mura is in a low-brightness state, the degree of the Mura is slight, namely the current difference is small, the brightness difference of sub-pixels is small, at the moment, a group of parameter values with larger duty ratio can be called, the luminous time is long, the value (such as Vdata) of corresponding adjustment current in the parameter values is small, the luminous intensity of a display panel is small, the brightness of the display panel determined according to the luminous intensity and the luminous time is unchanged as a whole, and the brightness uniformity of the display panel is improved; if the Mura is in a low-brightness state, the Mura is serious in degree, namely the current difference is large, the brightness difference of the sub-pixels is large, a group of parameter values with smaller duty ratio can be called at the moment, the light-emitting time is short, the value (such as Vdata) of the corresponding adjusting current in the parameter values is large, the light-emitting intensity of the display panel is large, the brightness of the display panel is determined according to the light-emitting intensity and the light-emitting time, the whole brightness of the display panel is unchanged, and the brightness uniformity of the display panel is improved. According to the invention, in the low-brightness state, the brightness compensation is carried out according to the different brightness degree of the display image, so that the display uniformity in the low-brightness state is improved.
Of course, it is not necessary for any one product embodying the invention to achieve all of the technical effects described above at the same time.
Other features of the present invention and its advantages will become apparent from the following detailed description of exemplary embodiments of the invention, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.
Fig. 1 is a schematic plan view of a display device according to the present invention;
FIG. 2 is a schematic diagram of a pixel circuit according to the present invention;
FIG. 3 is a timing diagram provided by the present invention;
FIG. 4 is a schematic diagram of duty cycle of two sets of light emission control signals provided by the present invention;
fig. 5 is a schematic plan view of another display device according to the present invention;
FIG. 6 is a flow chart of a driving method of a display device according to the present invention;
FIG. 7 is a flowchart of a method for determining the brightness non-uniformity of a display image according to the present invention;
FIG. 8 is a histogram of compensation value distributions;
FIG. 9 is another histogram of compensation value distributions;
Fig. 10 is a flow chart of real-time display of a display device according to the present invention.
Detailed Description
Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless it is specifically stated otherwise.
The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.
In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of exemplary embodiments may have different values.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.
When Mura is serious in a low-brightness state in the related art, the problem of uneven display cannot be effectively compensated, and the cause of Mura is as follows: due to the reasons of manufacturing the sub-pixel materials in the display panel, and the like, when the same voltage is supplied to the sub-pixels, different currents are generated, and the brightness of different sub-pixels is different, the larger the difference is, the more serious the Mura is, the smaller the difference is, and the more slight the Mura is. On the one hand, the human eyes have stronger recognition capability under low brightness when the light brightness is low, on the other hand, the light brightness difference can cause larger change of the overall difference percentage when the light brightness is low, the Mura is easier to show, and the brightness compensation can not be well carried out under the condition of low brightness Mura in the related technology.
In view of the above, the present invention provides a display device and a driving method thereof for effectively compensating for low-brightness Mura.
Referring to fig. 1,2, 3 and 4, fig. 1 is a schematic plan view of a display device according to the present invention, fig. 2 is a pixel circuit according to the present invention, fig. 3 is a timing chart according to the present invention, and fig. 4 is a schematic duty ratio of two sets of light emission control signals according to the present invention. The display device 1000 in fig. 1 includes: a display panel 100, the display panel 100 including a plurality of sub-pixels P; an image processing unit 200 coupled to the display panel 100, for processing the display image of the display panel 100, and determining the degree of uneven brightness of the display image; the compensation unit 300, coupled to the image processing unit 200, retrieves parameter values corresponding to duty ratios of different light emission control signals according to the degree of brightness non-uniformity of the display image, and performs brightness compensation on the display image.
Specifically, the display panel 100 may be an organic light emitting display panel 100, the image processing unit 200 is coupled to the display panel 100, processes a display image of the display panel 100, and determines a degree of brightness unevenness of the display image, and optionally, the image processing unit 200 may include an image capturing device and a determining module, where the image capturing device captures an image of the display panel 100, and the determining module determines a severity of the brightness unevenness of the display image, for example, may determine that the brightness unevenness is serious or slight, and is not limited herein.
In the present invention, the display device 1000 can effectively compensate for the display unevenness in the low-luminance state, that is, the average luminance of the display panel 100 is between 2nit and 110nit, or the average luminance of the display panel 100 is between 2nit and 90nit, which is not particularly limited herein.
The compensation unit 300 is coupled to the image processing unit 200, and adjusts the corresponding parameter values of duty ratios of different lighting control signals according to the brightness non-uniformity of the display image to perform brightness compensation on the display image, where the lighting control signals refer to lighting control signals Emit, and the duty ratios of the lighting control signals can determine the lighting time according to fig. 2 and 3. Two different sets of emission control signal Emit duty cycles are schematically shown in fig. 4, the first duty cycle being larger than the second duty cycle in fig. 4. Alternatively, the emission control signal Emit may be a pulse width modulation (PWM, pulse Width Modulation) signal.
The display panel 100 is shown in fig. 1 to further include a non-display area BB surrounding the display area AA, and fig. 1 illustrates the display panel 100 by way of example only as a rectangular display panel 100. In some other embodiments of the present application, the display panel 100 may also be embodied in other shapes, such as a circular, oval, or shaped structure. Fig. 1 shows only the case where the non-display area BB completely surrounds the display area AA, but the non-display area BB may also partially surround the display area AA (e.g., a water droplet screen), which is not particularly limited herein. Fig. 1 shows only a part of the sub-pixels P in the display area AA, and does not represent the actual number and arrangement of the sub-pixels P contained in the display area AA, and fig. 1 does not represent the actual size of the sub-pixels P, which is merely illustrative.
In this embodiment, the first non-display area BB1 and the 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 driven on a single side, so that the width of the first non-display area BB1 in the first direction X can be reduced, a narrow frame is implemented, the first shift register 21 provides the pixel circuit 000 with a light emission control signal Emit, that is, a signal for controlling whether the first transistor M1 and the fifth transistor M5 are turned on, and the second shift register 22 is located in the second non-display area BB2, that is, the second shift register 22 is driven on a single side, so that the width of the second non-display area BB2 in the first direction X can be reduced, the narrow frame is implemented, and the second shift register 22 provides the pixel circuit 000 with the first control signal S1. The positions of the first shift register 21 and the second shift register 22 are not particularly 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 frame, the second shift register 22 is located on the right frame, or the first shift register 21 is located on the right frame, and the second shift register 22 is located on the left frame. Also shown in fig. 1 is a third shift register 23, the third shift register 23 being located in both the first non-display area BB1 and the second non-display area BB2, i.e. the third shift register 23 is dual-edge driven, the third shift register 23 may provide the second control signal S2 to the pixel circuit 000.
As shown in fig. 2, the pixel driving circuit 000 includes: a first transistor M1 having a control terminal electrically connected to the light emitting signal input terminal, a first terminal electrically connected to the first power signal terminal VDD, and a second terminal electrically connected to the first terminal of the driving transistor M, the first power signal terminal VDD inputting the first power voltage PVDD; a second transistor M2 having a control terminal electrically connected to the second scan signal input terminal S2, a first terminal electrically connected to the data signal input terminal data, and a second terminal electrically connected to the first terminal of the driving transistor M; a driving transistor M having a control terminal electrically connected to the second terminal of the fourth transistor M4, and a first terminal electrically connected to the second terminal of the first transistor M1 and the second terminal of the second transistor M2; a third transistor M3 having a control terminal electrically connected to the second scan signal input terminal S2, a first terminal electrically connected to the second terminal of the fourth transistor M4 and the second terminal of the storage capacitor Cst, and a second terminal electrically connected to the second terminal of the driving transistor M and the first terminal of the fifth transistor M5; a fourth transistor M4 having a control terminal electrically connected to the first scan signal input terminal S1, a first terminal electrically connected to the reference voltage signal input terminal Vref, and a second terminal electrically connected to the control terminal of the driving transistor M; a fifth transistor M5 having a control terminal electrically connected to the light emitting signal input terminal Em, a first terminal electrically connected to the second terminal of the driving transistor M and the second terminal of the third transistor M3, and a second terminal electrically connected to the anode of the light emitting element O; a sixth transistor M6 having a control terminal electrically connected to the second scan signal input terminal, a first terminal electrically connected to the reference voltage signal input terminal, and a second terminal electrically connected to the first terminal of the light emitting element O; a light emitting element O having a first terminal electrically connected to the second terminal of the fifth transistor M5 and the second terminal of the sixth transistor M6, the second terminal electrically connected to the second power signal terminal VEE, and the second power signal terminal VEE inputting the second power voltage PVEE; the first terminal of the storage capacitor Cst is electrically connected to the first power signal terminal VDD, and the second terminal of the storage capacitor Cst 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.
The pixel circuit driving time sequence comprises a reset phase t1, a data writing phase t2 and a light emitting phase t3, wherein the reset phase t1, a fourth transistor M4 and a sixth transistor M6 are conducted, a reset signal Vref is respectively written into the first node N1 and the anode of the light emitting element O, the first node N1 is reset, the driving transistor M is conducted in response to the potential of the first node N1, the reset signal Vref is written into the anode of the light emitting element O, and the anode of the light emitting element O is reset; in the data writing stage t2, the second transistor M2 is turned on, and 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 emission 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 is known that the light emission time in the light emission stage is determined by the light emission control signal Emit, and if the duty ratio of the light emission control signal Emit is large, the light emission time is long, whereas the duty ratio of the light emission control signal Emit is small, and the light emission time is short. For example, a pulse train with a pulse width of 1 μs and a signal period of 4 μs, the light emission control signal duty ratio is 0.25.
The Mura visual effect under low brightness is worse in the related art, and the root cause of Mura generation is: when the same first power voltage is input, current difference is caused between different sub-pixels P due to material manufacturing and other reasons, so that display of the different sub-pixels P is uneven, and the more serious Mura is, the larger the difference caused by current is, and the larger the brightness difference of the sub-pixels P is. In the related art, the display panel 100 has only one set of data for the duty ratio of the emission control signal Emit when displaying, and only one set of corresponding parameter values for compensating uneven brightness, and the duty ratio of the emission control signal Emit is generally set higher, i.e. the emission time of the light emitting element O is longer, for the purposes of integrating power consumption, screen flashing and the like. The light-emitting brightness of the display panel 100 refers to the sum of the light-emitting intensities within a certain period of time, that is, the light-emitting brightness is determined by the light-emitting intensity and the light-emitting time, and the light-emitting time of the light-emitting element O is longer, so that the light-emitting intensity is correspondingly lower, the current is smaller, the percentage of the current difference is larger, and then the percentage of the luminance difference of the sub-pixels P is larger, so that the visual effect of the display panel 100 with heavy Mura is poor.
In the present invention, the display device 1000 may take parameter values corresponding to different duty ratios of the light emission control signals Emit according to the severity of Mura to compensate, and it is understood that the parameter values herein are mainly related parameters capable of adjusting the current, and certainly mainly include data voltages, and also include data such as the first power supply voltage PVDD and the second power supply voltage PVEE, which are not limited herein specifically.
As is known from the above, the light-emitting brightness of the display panel 100 is the sum of the light-emitting intensities within a certain period of time, that is, the light-emitting brightness is determined by the light-emitting intensity and the light-emitting time, the light-emitting time is determined by the duty ratio duty of the light-emitting control signal Emit, the larger the duty ratio duty of the light-emitting control signal Emit is, the longer the light-emitting time is, the light-emitting intensity can be correspondingly reduced if the light-emitting brightness is unchanged, whereas the smaller the duty ratio duty of the light-emitting control signal Emit is, the shorter the light-emitting time is, the light-emitting intensity can be correspondingly increased if the light-emitting brightness is unchanged, that is, the current is increased, the specific gravity of the current difference between the different sub-pixels P is reduced, for example, the current difference is 0.1 nit, the current difference ratio is 10%, the brightness of the display panel 100 is integrally improved to 2nit, the current difference ratio is reduced to 5%, and the difference ratio is correspondingly reduced, and the display uniformity is improved.
The display device 1000 of the present invention includes an image processing unit 200 and a compensation unit 300, where the image processing unit 200 determines the degree of uneven brightness of a display image in a low brightness state, that is, determines the severity of Mura, and the compensation unit 300 adjusts parameter values corresponding to duty ratios of different lighting control signals according to the degree of uneven brightness of the display image, so as to perform brightness compensation on the display image, and if the degree of Mura is slight in the low brightness state, that is, the current difference is small, the luminance difference of sub-pixels P is small, at this time, a set of parameter values with larger duty ratio can be invoked, the lighting time is long, the value (such as Vdata) of the corresponding adjustment current in the parameter values of the Demura table is small, the lighting intensity of the display panel 100 is small, and the brightness of the display panel 100 determined according to the lighting intensity and the lighting time is unchanged as a whole, so as to improve the brightness uniformity of the display panel 100; if the Mura is in a low-brightness state, the Mura is more serious, i.e., the current difference is larger, the luminance difference of the sub-pixels P is larger, at this time, a group of smaller parameter values with smaller duty ratio can be called, the light-emitting time is short, the value (such as Vdata) of the parameter values in the Demura table, which corresponds to the adjusting current, is larger, the light-emitting intensity of the display panel 100 is larger, the luminance of the display panel 100, which is determined according to the light-emitting intensity and the light-emitting time, is unchanged as a whole, and the luminance uniformity of the display panel 100 is improved. According to the invention, in the low-brightness state, the brightness compensation is carried out according to the different brightness degree of the display image, so that the display uniformity in the low-brightness state is improved.
In some alternative embodiments, referring to fig. 5 in combination with fig. 4, fig. 5 is a schematic plan view of still another display device according to the present invention, and further includes a storage unit 400 coupled to the compensation unit 300, where the storage unit 400 includes a first set of parameter values and a second set of parameter values, the first set of parameter values corresponds to a first duty cycle, and the second set of parameter values corresponds to a second duty cycle, and the first duty cycle is greater than the second duty cycle.
Optionally, the storage unit 400 may be located in the display driving chip, or may be a memory Flash, that is, the first set of parameter values and the second set of parameter values may be burned in the display driving chip, or may be stored in the memory Flash, in fig. 5, only the storage unit 400 is taken as the memory Flash for schematic illustration, as shown in fig. 4, where the first duty cycle is greater than the second duty cycle, and the first duty cycle is a set of duty cycle values, and the second duty cycle is also a set of duty cycle values, as shown in the graph in fig. 4, where the first set of parameter values corresponds to the first duty cycle, the second set of parameter values corresponds to the second duty cycle, the parameter values corresponding to the first duty cycle are smaller, the light-emitting time is longer, the parameter values (such as Vdata) corresponding to the adjusting current in the parameter values in the Demura table are smaller, the brightness of the display panel 100 is determined according to the light-emitting intensity and the light-emitting time is unchanged, and the brightness uniformity of the display panel 100 is improved; the second duty ratio is smaller than a group of parameter values, the lighting time is shorter, the value (such as Vdata) of the parameter values of Demura table corresponding to the adjusting current is larger, the lighting intensity of the display panel 100 is larger, the brightness of the display panel 100 determined according to the lighting intensity and the lighting time is unchanged as a whole, and the brightness uniformity of the display panel 100 is improved.
In some alternative embodiments, with continued reference to fig. 1, the image processing unit 200 determines that the brightness of the display image is uneven to a first level or a second level, and when determining that the brightness is uneven to the first level, invokes a first set of parameter values corresponding to the first duty ratio to perform brightness adjustment on the display image of the display panel 100; and when the degree of the uneven brightness is judged to be the second level, a second group of parameter values corresponding to a second duty ratio are called, and the first duty ratio is larger than the second duty ratio, so that brightness adjustment is performed on the display image of the display panel 100.
It can be understood that the first level may be slight and the second level may be severe, and the image processing unit 200 determines that the brightness of the display image is uneven to be the first level, that is, mura is slight, and invokes a first set of parameter values corresponding to the first duty ratio to perform brightness adjustment on the display image of the display panel 100; the image processing unit 200 determines that the brightness of the display image is uneven to a second level, that is, mura is serious, and invokes a second set of parameter values corresponding to the second duty ratio to perform brightness adjustment on the display image of the display panel 100.
Specifically, the image processing unit 200 determines the degree of uneven brightness of the display image in the low brightness state, that is, determines the severity of Mura, the compensation unit 300 invokes parameter values corresponding to different duty ratios of the light emission control signals according to the degree of uneven brightness of the display image, performs brightness compensation on the display image, if the degree of Mura is slight in the low brightness state, that is, the current difference is small, the brightness difference of the sub-pixels P is small, at this time, a group of parameter values corresponding to the first duty ratio with a larger duty ratio can be invoked, the light emission time is long, the value (such as Vdata) of the corresponding adjustment current in the parameter values of the Demura table is small, the light emission intensity of the display panel 100 is small, the brightness of the display panel 100 determined according to the light emission intensity and the light emission time is unchanged as a whole, and the brightness uniformity of the display panel 100 is improved; if the Mura is in a low-brightness state, the Mura is more serious, i.e., the current difference is larger, the luminance difference of the sub-pixels P is larger, at this time, a group of parameter values corresponding to the second duty ratio with smaller duty ratio can be called, the light-emitting time is short, the value (e.g., vdata) of the parameter values corresponding to the adjusting current in the Demura table is larger, the light-emitting intensity of the display panel 100 is larger, the luminance of the display panel 100 determined according to the light-emitting intensity and the light-emitting time is unchanged as a whole, and the luminance uniformity of the display panel 100 is improved. According to the invention, in the low-brightness state, different parameter values are called according to whether the brightness non-uniformity degree of the display image is the first level or the second level to carry out brightness compensation, so that the display uniformity in the low-brightness state is improved.
Based on the same inventive concept, the present invention further provides a driving method of a display device, referring to fig. 6, fig. 6 is a flowchart of a driving method of a display device provided by the present invention, where the driving method in fig. 6 includes:
s101: acquiring a display image of a display panel;
S102: judging the degree of uneven brightness of the display image, wherein the degree of uneven brightness comprises a first stage and a second stage, and the first stage is smaller than the second stage;
S103: when the degree of uneven brightness is judged to be the first level, a first group of parameter values corresponding to the first duty ratio are called, and brightness adjustment is carried out on the display image of the display panel; and when the degree of uneven brightness is judged to be the second level, a second group of parameter values corresponding to a second duty ratio are called, and the first duty ratio is larger than the second duty ratio, so that brightness adjustment is carried out on the display image of the display panel.
Specifically, S101: the display images of the display panel are obtained in which the display images at the key luminance values, for example, the display images at the low luminance states of 2nit, 5nit, 10nit, 26nit, 90nit, 110nit, are obtained, and the key luminance values are not particularly limited herein, as for the luminance images between 2nit and 5nit, the luminance images between 5nit and 10nit, the luminance images between 10nit and 26nit, the luminance images between 26nit and 90nit, and the luminance images between 90nit and 110nit, can be calculated in the form of linear differences.
Step S102: judging the degree of uneven brightness of the display image, wherein the degree of uneven brightness comprises a first stage and a second stage, the first stage is smaller than the second stage, the mode of judging the degree of uneven brightness is not particularly limited, the first stage can represent that the degree of uneven brightness is slight, and the second stage represents that the degree of uneven brightness is serious.
Step S103: when the degree of uneven brightness is judged to be the first level, a first group of parameter values corresponding to the first duty ratio are called, and brightness adjustment is carried out on the display image of the display panel; when judging that the degree of uneven brightness is the second level, calling a second group of parameter values corresponding to the second duty ratio, wherein the first duty ratio is larger than the second duty ratio, carrying out brightness adjustment on a display image of the display panel, specifically judging that the degree of uneven brightness of the display image is the first level or the second level in a low-brightness state, namely judging the severity of Mura, if the degree of Mura is smaller in the low-brightness state, namely the current difference is smaller, the luminance difference of sub-pixels is smaller, calling a first group of parameter values corresponding to the first duty ratio with larger duty ratio at the moment, the lighting time is long, the value (such as Vdata) of the corresponding adjustment current in the parameter values of a Demura table is smaller, the lighting intensity of the display panel is smaller, and the brightness of the display panel determined according to the lighting intensity and the lighting time is unchanged as a whole, so that the brightness uniformity of the display panel is improved; if the Mura is in a low-brightness state, the Mura is serious in degree, namely the current difference is large, the brightness difference of the sub-pixels is large, at the moment, a second group of parameter values corresponding to a second duty ratio with smaller duty ratio can be called, the light-emitting time is short, the value (such as Vdata) of the parameter values in the Demura table, which corresponds to the adjusting current, is large, the light-emitting intensity of the display panel is large, the brightness of the display panel is determined according to the light-emitting intensity and the light-emitting time is unchanged as a whole, and the brightness uniformity of the display panel is improved.
According to the invention, in the low-brightness state, different parameter values are called according to whether the brightness non-uniformity degree of the display image is the first level (Mura slight) or the second level (Mura severe) to carry out brightness compensation, so that the display uniformity in the low-brightness state is improved.
In some alternative embodiments, continuing with fig. 6, the first set of parameter values includes a first gamma value and a first brightness compensation parameter value; the second set of parameter values includes a second gamma value and a second brightness compensation parameter value.
Specifically, the parameter values mainly include a gamma value for adjusting luminance of the sub-pixels and a luminance compensation parameter, for example, an average luminance of the display image is 50nit, then a difference between the luminance of each sub-pixel in the display image and the average luminance needs to be calculated, the luminance difference is converted into a gray level difference value, and then the gray level difference value, that is, offset, is recorded in the storage unit, and in addition, a voltage value, for example, a data voltage Vdata, needed when the luminance of each sub-pixel is adjusted to the average luminance needs to be stored. According to the invention, the first group of parameter values comprise a first gamma value and a first brightness compensation parameter value, the second group of parameter values comprise a second gamma value and a second brightness compensation parameter value, the first gamma value of the first group of parameter values and the first brightness compensation parameter value correspond to a first duty ratio, the first duty ratio is larger, the light-emitting time is long, the light-emitting intensity regulated by the first gamma value and the first brightness compensation parameter value is small, the whole light-emitting brightness of the display panel can be kept unchanged, the second gamma value of the second parameter value and the second brightness compensation parameter value correspond to a second duty ratio, the second duty ratio is smaller than the first duty ratio, the light-emitting time is short, and the light-emitting intensity regulated by the second gamma value and the second brightness compensation parameter value is large, so that the whole light-emitting brightness of the display panel is kept unchanged.
In some alternative embodiments, referring to fig. 7,8 and 9, fig. 7 is a flowchart of a method for determining a brightness non-uniformity degree of a display image according to the present invention, fig. 8 is a histogram of a compensation value distribution, and fig. 9 is another histogram of a compensation value distribution, where determining a brightness non-uniformity degree of a display image includes:
s201: setting an average brightness value of the display image;
s202: the brightness of each sub-pixel in the display image is obtained, the brightness difference value between the brightness of each sub-pixel and the average brightness value is calculated, and the brightness difference value is converted into a gray scale difference value;
S203: acquiring gray level difference distribution of all sub-pixels;
s204: when the gray level difference value is larger than a first preset threshold value, the gray level difference value is extracted, the percentage of all gray level difference values exceeding the first preset threshold value is calculated, and the degree of uneven brightness is judged according to the percentage.
Specifically, step S201: the average luminance value of the display image is set, wherein the average luminance value of the display image is selected, for example, a display image with average luminance of 32nit can be selected as a basis, the display image with other luminance can be calculated according to a linear difference method, the average luminance value of the set display image is not specifically limited, and the average luminance value of the set display image can be selected to be 2nit, 10nit, 26nit, 135nit and the like.
Step S202: the brightness of each sub-pixel in the display image is obtained, the brightness difference between the brightness of each sub-pixel and the average brightness value is calculated, the brightness difference is converted into a gray level difference, further, the brightness of each sub-pixel is obtained, for example, the brightness of the sub-pixel is 19nit, 20nit, 19nit, 23nit, 28nit, 26nit, 30nit … …, etc., and the average brightness value is set to 26nit, then the brightness difference is 7nit, 6nit, 7nit, 3nit, 2nit, 0, 4nit … …, and the brightness difference is converted into a gray level difference, for example, 7, 6, 7, 3, 2, 0, -4 … …, which is only illustrative and is not limited as a practical product.
Step S203: the gray level difference distribution of all the sub-pixels is obtained, as shown in fig. 8 and 9, i.e., a histogram of the gray level difference distribution, for example, the gray level differences are respectively 7, 6, 7, 3, 2, 0, -4 … …, and the gray level difference is 7 is schematically illustrated, if the number of the sub-pixels is 300 ten thousand, the number of the gray level differences is 5000, the sub-pixels with the gray level difference of 7 occupy 5000/300 ten thousand, i.e., 0.16%.
Step S204: when the gray level difference value is larger than a first preset threshold value, the gray level difference value is extracted, the percentage of all gray level difference values exceeding the first preset threshold value is calculated, and the degree of uneven brightness is judged according to the percentage. The first preset threshold is preset and in some alternative embodiments, with continued reference to FIGS. 8 and 9, is n, 2.ltoreq.n.ltoreq.4. The first preset threshold n in the present invention may be 2,3, or 4, which is not specifically limited herein. For example, if the gray level difference value is set to be greater than or equal to-3 and less than or equal to 3, the gray level difference value is set to be smaller, then the difference of the brightness of the sub-pixels is regarded as smaller, namely the Mura is slight, but if the gray level difference value is greater than or equal to 3 or less than-3, the gray level difference value is extracted, the sum of the percentages of all the gray level difference values exceeding a first preset threshold is calculated, the severity of the Mura is determined according to the size of the sum of the percentages, if the sum of the percentages is smaller, the Mura is slight, and if the sum of the percentages is larger, the Mura is serious.
In some alternative embodiments, with continued reference to fig. 8 and 9, the percentage is less than a second preset threshold, the degree of brightness non-uniformity is a first level, the percentage is greater than the second preset threshold, and the degree of brightness non-uniformity is a second level.
In some alternative embodiments, the second preset threshold is m,10% m 15%.
Taking the first preset threshold value of 3 and the second preset threshold value of 10% as an example, the sum of the percentages of all sub-pixels with gray scale difference values smaller than-3 in fig. 8 is 0.42% and smaller than 10%, so the degree of brightness unevenness is regarded as the first level, i.e. Mura is slight. In fig. 9, the gray level difference value is 14.2% and more than 10% in percentage of all sub-pixels smaller than-3, so that the degree of brightness unevenness is regarded as the second level, i.e., mura is serious.
If the Mura degree is the first level in the low-brightness state, namely the current difference is smaller, the brightness difference of the sub-pixels is smaller, a group of parameter values with larger duty ratio can be called at the moment, the light-emitting time is long, the value (such as Vdata) of the parameter values in the Demura table, which corresponds to the adjusting current, is smaller, the light-emitting intensity of the display panel is smaller, the brightness of the display panel is determined according to the light-emitting intensity and the light-emitting time, and the brightness uniformity of the display panel is improved; if the Mura is in the low-brightness state, the Mura is in the second stage, that is, the current difference is larger, the luminance difference of the sub-pixels is larger, a group of parameter values with smaller duty ratio can be called at the moment, the light-emitting time is short, the value (such as Vdata) of the parameter values in the Demura table, which corresponds to the adjusting current, is larger, the light-emitting intensity of the display panel is larger, the luminance of the display panel is determined according to the light-emitting intensity and the light-emitting time, and the luminance uniformity of the display panel is improved.
Referring to fig. 10, fig. 10 is a flow chart of a real-time display of a display device provided by the present invention, wherein fig. 10 shows that a flag bit is read first, where the flag bit has no practical meaning, only serves as a flag, then it is determined whether the sum of percentages of gray level difference values greater than 3 is greater than 10%, if the sum of percentages is smaller than 10%, then the first gamma value corresponding to the first duty ratio and the first brightness compensation parameter value are called, and if the sum of percentages is greater than 10%, then the second gamma value corresponding to the second duty ratio and the second brightness compensation parameter value are called, and the display panel displays.
As can be seen from the above embodiments, the display device and the driving method thereof provided by the present invention at least achieve the following beneficial effects:
The display device comprises an image processing unit and a compensation unit, wherein the image processing unit judges the degree of uneven brightness of a display image in a low-brightness state, namely judges the severity of Mura, the compensation unit calls parameter values corresponding to different luminous control signal duty ratios according to the degree of uneven brightness of the display image, brightness compensation is carried out on the display image, if the Mura is in a low-brightness state, the degree of the Mura is slight, namely the current difference is small, the brightness difference of sub-pixels is small, at the moment, a group of parameter values with larger duty ratio can be called, the luminous time is long, the value (such as Vdata) of corresponding adjustment current in the parameter values is small, the luminous intensity of a display panel is small, the brightness of the display panel determined according to the luminous intensity and the luminous time is unchanged as a whole, and the brightness uniformity of the display panel is improved; if the Mura is in a low-brightness state, the Mura is serious in degree, namely the current difference is large, the brightness difference of the sub-pixels is large, a group of parameter values with smaller duty ratio can be called at the moment, the light-emitting time is short, the value (such as Vdata) of the corresponding adjusting current in the parameter values is large, the light-emitting intensity of the display panel is large, the brightness of the display panel is determined according to the light-emitting intensity and the light-emitting time, the whole brightness of the display panel is unchanged, and the brightness uniformity of the display panel is improved. According to the invention, in the low-brightness state, the brightness compensation is carried out according to the different brightness degree of the display image, so that the display uniformity in the low-brightness state is improved.
While certain specific embodiments of the invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.
Claims (8)
1. A display device, comprising:
A display panel including a plurality of subpixels;
The image processing unit is coupled with the display panel, processes the display image of the display panel and judges the degree of uneven brightness of the display image;
the image processing unit judges that the degree of uneven brightness of the display image is a first level or a second level, and the first level is smaller than the second level;
when the degree of the uneven brightness is judged to be the first level, a first group of parameter values corresponding to a first duty ratio are called, and brightness adjustment is carried out on the display image of the display panel;
When the degree of the uneven brightness is judged to be the second level, a second group of parameter values corresponding to a second duty ratio are called, the first duty ratio is larger than the second duty ratio, and brightness adjustment is carried out on the display image of the display panel;
and the compensation unit is coupled with the image processing unit, and is used for calling the corresponding parameter values of different luminous control signal duty ratios according to the uneven brightness degree of the display image so as to carry out brightness compensation on the display image.
2. The display device of claim 1, further comprising a memory unit coupled to the compensation unit, the memory unit including a first set of parameter values corresponding to a first duty cycle and a second set of parameter values corresponding to a second duty cycle, the first duty cycle being greater than the second duty cycle.
3. A driving method of a display device, comprising:
Acquiring a display image of a display panel;
Judging the degree of uneven brightness of the display image, wherein the degree of uneven brightness comprises a first stage and a second stage, and the first stage is smaller than the second stage;
When the degree of the uneven brightness is judged to be the first level, a first group of parameter values corresponding to a first duty ratio are called, and brightness adjustment is carried out on the display image of the display panel; and when the degree of the uneven brightness is judged to be the second level, invoking a second group of parameter values corresponding to a second duty ratio, wherein the first duty ratio is larger than the second duty ratio, and performing brightness adjustment on the display image of the display panel.
4. A driving method of a display device according to claim 3, wherein the first set of parameter values includes a first gamma value and a first brightness compensation parameter value; the second set of parameter values includes a second gamma value and a second brightness compensation parameter value.
5. A driving method of a display device according to claim 3, wherein determining the degree of the display image luminance unevenness comprises:
setting an average brightness value of the display image;
Acquiring the brightness of each sub-pixel in the display image, calculating the brightness difference value between the brightness of each sub-pixel and the average brightness value, and converting the brightness difference value into a gray level difference value;
acquiring gray level difference distribution of all sub-pixels;
when the gray level difference value is larger than a first preset threshold value, the gray level difference value is extracted, the percentage of all gray level difference values exceeding the first preset threshold value is calculated, and the degree of uneven brightness is judged according to the percentage.
6. The driving method of a display device according to claim 5, wherein the percentage is smaller than a second preset threshold, the degree of brightness unevenness is a first level, the percentage is larger than the second preset threshold, and the degree of brightness unevenness is a second level.
7. The method of driving a display device according to claim 5, wherein the first preset threshold value is n, 2.ltoreq.n.ltoreq.4.
8. The driving method of a display device according to claim 6, wherein the second preset threshold value is m,10% or less and 15% or less.
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