CN115641814A - 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, 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 uneven brightness degree of the display image; and the compensation unit is coupled with the image processing unit and used for calling parameter values corresponding to the duty ratios of different light-emitting control signals according to the uneven brightness of the displayed image so as to carry out brightness compensation on the displayed image. According to the invention, the parameter values corresponding to the duty ratios of different light-emitting control signals are adjusted according to the severity of uneven brightness distribution of the display image, so that the brightness compensation is carried out on the display image, and the uniformity under low brightness can be improved.
Description
Technical Field
The present invention relates to the field of display technologies, and in particular, to a display device and a driving method thereof.
Background
With the development of electronic technology, the manufacture of display panels is also mature, and the display panels provided by the prior art include liquid crystal display panels, organic light emitting display panels, plasma display panels, and the like. Organic Light Emitting Diodes (OLEDs) are increasingly used in high performance display as a current-mode light emitting device, and OLED display panels have many excellent characteristics such as self-luminescence, wide viewing angle, fast response speed, high contrast, wide color gamut, low energy consumption, thin panels, rich colors, flexible display, and wide operating temperature range, and are therefore known as "star" flat panel display technologies of the next generation. The OLED display panel comprises an anode, a cathode, a hole transport layer, an organic light emitting layer and an electron transport layer, wherein the hole transport layer, the organic light emitting layer and the electron transport layer are arranged between the anode and the cathode, the anode provides hole injection, the cathode provides electron injection, holes and electrons injected by the cathode and the anode are compounded in the organic light emitting layer under the driving of an external voltage to form electron-hole pairs (namely excitons) at bound energy levels, and the excitons radiate and de-excite to emit photons to generate visible light.
Mura refers to the phenomenon that the brightness in the display panel is not uniform, and various traces are caused, and the reason why Mura is caused is that, due to the reason that the sub-pixel materials in the display panel are made, when the same voltage is supplied to the sub-pixels, the generated currents are different, and the brightness of different sub-pixels is different, the difference is larger, the more serious the Mura is, the smaller the difference is, and the smaller the Mura is.
Aiming at the problem, the brightness of the pixel points can be corrected by means of Demura compensation and gray scale compensation, and therefore the Mura phenomenon is improved. The gray scale compensation is to change the gray scale of the pixel to improve the brightness uniformity. The Demura process is to shoot the Mura condition of a gray scale picture through a camera, extract and correct the Mura through algorithms when an input image is a single gray scale picture according to the brightness of a central area of a panel so as to increase a certain gray scale compensation value for pixels in a dark area and reduce a certain gray scale compensation value for pixels in a bright area, thereby improving the Mura phenomenon. The compensation values (or Demura data) for all pixels can be made into a Demura table for hardware to process.
However, in the prior art, when Mura of the display panel is serious and low-brightness, effective compensation cannot be carried out.
Therefore, it is desirable to provide a display device and a driving method thereof capable of effectively compensating for an uneven display screen 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 perform effective compensation according to the severity of the Mura of the display panel.
In one aspect, the present invention provides a display device comprising: a display panel including 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 uneven brightness degree of the display image; and the compensation unit is coupled with the image processing unit and used for calling parameter values corresponding to duty ratios of different light-emitting control signals according to the uneven brightness of the display image so as to carry out brightness compensation on the display image.
In another aspect, the present invention further provides a driving method of a display device, including obtaining a display image of a display panel;
judging the uneven brightness degree of the display image, wherein the uneven brightness degree comprises a first level and a second level, and the first level is smaller than the second level;
when the brightness unevenness degree is judged to be a first level, calling a first group of parameter values corresponding to a first duty ratio to regulate the brightness of the display image of the display panel; and when the brightness unevenness degree is judged to be a second level, calling 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 adjusting the brightness of the display image of the display panel.
Compared with the prior art, the display device and the driving method thereof provided by the invention at least realize the following beneficial effects:
the display device comprises an image processing unit and a compensation unit, wherein the image processing unit judges the uneven brightness degree of a display image in a low-brightness state, namely judges the severity degree of Mura, the compensation unit calls parameter values corresponding to different light-emitting control signal duty ratios according to the uneven brightness degree of the display image to perform brightness compensation on the display image, if the Mura degree is slight in the low-brightness state, namely the current difference is small, the brightness difference of sub-pixels is small, at the moment, a group of parameter values with large duty ratios can be called, the light-emitting time is long, the numerical values (such as Vdata) corresponding to the adjusting current in the parameter values are small, the light-emitting intensity of the display panel is small, the brightness of the display panel determined according to the light-emitting intensity and the light-emitting time is not changed as a whole, and the brightness uniformity of the display panel is improved; if the Mura degree is more serious in a low-brightness state, namely the current difference is larger, the sub-pixel brightness difference is larger, a group of parameter values with smaller duty ratio can be called, the light-emitting time is short, the value (such as Vdata) corresponding to the regulated current in the parameter values is larger, the light-emitting intensity of the display panel is larger, the brightness of the display panel determined according to the light-emitting intensity and the light-emitting time is not changed integrally, and the brightness uniformity of the display panel is improved. According to the invention, under the low-brightness state, the brightness compensation is carried out according to different degrees of the uneven brightness of the displayed image, so that the display uniformity under the low-brightness state is improved.
Of course, it is not necessary for any product in which the invention is practiced to achieve all of the above-described technical effects simultaneously.
Other features of the present invention and advantages thereof 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 pixel circuit provided in the present invention;
FIG. 3 is a timing diagram provided by the present invention;
FIG. 4 is a schematic diagram of duty ratios of two sets of light emission control signals provided by the present invention;
FIG. 5 is a schematic plane view of another display device provided in the present invention;
FIG. 6 is a flowchart of a driving method of a display device according to the present invention;
FIG. 7 is a flowchart of a method for determining a brightness non-uniformity of a displayed image according to the present invention;
FIG. 8 is a histogram of a compensation value distribution;
FIG. 9 is a histogram of another compensation value distribution;
fig. 10 is a real-time display flowchart 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, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.
The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.
Techniques, methods, and apparatus known to those 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 particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be discussed further in subsequent figures.
In the related art, when Mura is serious in a low-brightness state, the problem of uneven display cannot be effectively compensated, and the reason for Mura is as follows: due to the fact that sub-pixel materials in the display panel are made, when the same voltage is supplied to the sub-pixels, the generated currents are different, and the different is shown in the brightness difference of the different sub-pixels, the larger the difference is, the more serious the Mura is, the smaller the difference is, and the more slight the Mura is. On one hand, because the human eyes have stronger recognition capability under low brightness when the brightness is low, on the other hand, the slight brightness difference can cause larger change of the whole difference percentage when the brightness is low, mura is more easily reflected, and the brightness compensation can not be well carried out when the brightness is low in the related technology.
Accordingly, the present invention provides a display device and a driving method thereof for effectively compensating for low-brightness Mura.
Referring to fig. 1, fig. 2, fig. 3 and fig. 4, fig. 1 is a schematic plane structure diagram 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 diagram according to the present invention, and fig. 4 is a schematic duty ratio diagram of two sets of light-emitting 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 subpixels 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 brightness unevenness of the display image; the compensation unit 300 is coupled to the image processing unit 200, and retrieves corresponding parameter values of duty ratios of different light-emitting control signals according to the non-uniform brightness of the display image, so as to perform 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, and processes the display image of the display panel 100 to determine the uneven brightness degree of the display image, optionally, the image processing unit 200 may include an image capturing device and a determining module, the image capturing device performs image capturing on the display image of the display panel 100, and the determining module determines the uneven brightness degree of the display image, for example, it may be determined that the uneven brightness degree is serious or slight, which is not specifically limited herein.
It should be noted that, in the present invention, the display apparatus 1000 can effectively compensate the display unevenness in the low-luminance state, where 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, and the average value of the low-luminance is not specifically limited herein.
The compensation unit 300 is coupled to the image processing unit 200, and is configured to retrieve parameter values corresponding to duty ratios of different light-emitting control signals according to the non-uniform brightness of the display image, so as to perform brightness compensation on the display image, where the light-emitting control signal is the light-emitting control signal Emit, and the duty ratio of the light-emitting control signal determines the length of the light-emitting time, with reference to fig. 2 and 3. Two different sets of duty cycles of the emission control signal Emit are schematically shown in fig. 4, the first duty cycle being larger than the second duty cycle as in fig. 4. Alternatively, the emission control signal Emit may be a Pulse Width Modulation (PWM) signal.
The display panel 100 is shown in fig. 1 to further include a non-display area BB surrounding the display area AA, fig. 1 only illustrates the display panel 100 as a rectangular display panel 100, and in some other embodiments of the present application, the display panel 100 may also be embodied in other shapes, such as a circle, an ellipse, or an irregular structure. Fig. 1 only shows a 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 (for example, a water droplet screen), and is not limited herein. Fig. 1 only shows a part of the sub-pixels P in the display area AA, respectively, and does not represent the actual number and arrangement of the sub-pixels P included in the display area AA, and fig. 1 also does not represent the actual size of the sub-pixels P, which is only schematic.
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 driven by a single side, so that the width of the first non-display area BB1 in the first direction X can be reduced, to realize a narrow frame, the first shift register 21 provides the light emission control signal Emit for the pixel circuit 000, that is, a signal for controlling whether the first transistor M1 and the fifth transistor M5 are turned on, and similarly, the second shift register 22 is located in the second non-display area BB2, that is, the second shift register 22 is driven by a single side, so that the width of the second non-display area BB2 in the first direction X can be reduced, to realize a narrow frame, and the second shift register 22 provides the 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 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. Fig. 1 also shows a third shift register 23, where the third shift register 23 is located in both the first non-display area BB1 and the second non-display area BB2, that is, the third shift register 23 is driven bilaterally, and the third shift register 23 can provide the second control signal S2 for the pixel circuit 000.
As shown in fig. 2, the pixel drive circuit 000 includes: a control end of the first transistor M1 is electrically connected to the light-emitting signal input end, a first end of the first transistor M is electrically connected to a first power signal end VDD, a second end of the first transistor M is electrically connected to a first end of the driving transistor M, and a first power voltage PVDD is input to the first power signal end VDD; a control end of the second transistor M2 is electrically connected with the second scanning signal input end S2, a first end is electrically connected with the data signal input end data, and a second end is electrically connected with the first end of the driving transistor M; a control end of the driving transistor M is electrically connected with the second end of the fourth transistor M4, and a first end of the driving transistor M is electrically connected with the second end of the first transistor M1 and the second end 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 emission 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 first end of the light emitting element O is electrically connected to the second end of the fifth transistor M5 and the second end of the sixth transistor M6, a second end of the light emitting element O is electrically connected to the second power signal terminal VEE, and the second power signal terminal VEE inputs the second power voltage PVEE; a first terminal of the storage capacitor Cst is electrically connected to the first power signal terminal VDD, and a second terminal thereof 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 stage t1, a data writing stage t2 and a light emitting stage t3, the reset stage t1, a fourth transistor M4 and a sixth transistor M6 are conducted, a reset signal Vref is respectively written into a first node N1 and the anode of a light emitting element O to reset the first node N1, the driving transistor M is conducted in response to the potential of the first node N1, a 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, 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 period 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. Therefore, the light-emitting time in the light-emitting stage is determined by the light-emitting control signal Emit, and if the duty ratio of the light-emitting control signal Emit is large, the light-emitting time is longer, while if the duty ratio of the light-emitting control signal Emit is small, the light-emitting time is shorter. For example, the pulse width is 1 μ s, the signal period is 4 μ s, and the duty ratio of the emission control signal is 0.25.
In the related art, the visual effect of Mura under low brightness is worse, and the root cause of the Mura is as follows: when the same first power voltage is input, the current difference is caused between different sub-pixels P due to the material manufacture and the like, so that the display unevenness of different sub-pixels P is caused. In the related art, the duty ratio of the emission control signal Emit has only one set of data and only one set of corresponding parameter values for compensating the luminance unevenness no matter whether the display panel 100 is high or low when displaying, but the duty ratio of the emission control signal Emit is generally set to be higher, that is, the emission time of the light emitting element O is longer, in order to solve the problems of the power consumption and the flicker. The luminance of the display panel 100 is the sum of the luminance intensities within a certain time, i.e. the luminance is determined by both the luminance intensities and the luminance times, and the luminance time of the light-emitting element O is longer, so the luminance 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-pixel P is larger, so the visual effect of the display panel 100 with heavier Mura is deteriorated.
In the present invention, the display device 1000 may call different parameter values corresponding to duty ratios of the emission control signal Emit according to the severity of Mura to perform compensation, and it is understood that the parameter values are mainly related parameters capable of adjusting the current magnitude, and certainly mainly data voltages, and also include data such as the first power voltage PVDD and the second power voltage PVEE, which are not specifically limited herein.
As known from the above, the light-emitting brightness of the display panel 100 refers to the sum of the light-emitting intensities within a certain 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 of the light-emitting control signal Emit, the larger the duty ratio of the light-emitting control signal Emit is, the longer the light-emitting time is, if the light-emitting brightness is not changed, the light-emitting intensity can be correspondingly reduced, otherwise, the light-emitting time is shorter the smaller the duty ratio of the light-emitting control signal Emit is, if the light-emitting brightness is not changed, the light-emitting intensity can be increased in response, that is, the current is increased, and once the current is increased, the ratio of the current difference between different sub-pixels P is reduced, for example, the current difference is 0.1, and the light-emitting brightness is 1nit, the ratio of the current difference is reduced to 5%, and the ratio of the difference is correspondingly reduced, so that the display uniformity is improved.
The display device 1000 of the invention includes the image processing unit 200 and compensating unit 300, the image processing unit 200 judges the uneven degree of the display image luminance under the low-bright state, namely judge the severity of Mura, the compensating unit 300 transfers the parameter value corresponding to different duty ratios of the luminous control signal according to the uneven degree of the display image luminance, carry on the luminance compensation to the display image, if under the low-bright state, the degree of Mura is minor, namely the current difference is minor, the luminance difference of the subpixel P is minor, can transfer a group of parameter values with larger duty ratios at this moment, the luminous time is long, the value (such as Vdata) of the corresponding regulating current in the parameter value of the Demura table is minor, the luminous intensity of the display panel 100 is minor, the luminance of the display panel 100 confirmed according to luminous intensity and luminous time is invariable wholly, improve the luminance uniformity of the display panel 100; if the Mura degree is relatively serious in a low-brightness state, that is, the current difference is relatively large, and the brightness difference of the sub-pixel P is relatively large, at this time, a group of parameter values with a relatively small duty ratio can be called, the light emitting time is short, the value (for example, vdata) corresponding to the adjustment current in the parameter values of the Demura table is relatively large, the light emitting intensity of the display panel 100 is relatively large, the brightness of the display panel 100 determined according to the light emitting intensity and the light emitting time is not changed as a whole, and the brightness uniformity of the display panel 100 is improved. According to the invention, under the low-brightness state, the brightness compensation is carried out according to different uneven brightness degrees of the display image, so that the display uniformity under the low-brightness state is improved.
In some optional embodiments, referring to fig. 5 in combination with fig. 4, fig. 5 is a schematic plan view of a display device according to still another embodiment of the present invention, which 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 ratio, the second set of parameter values corresponds to a second duty ratio, and the first duty ratio is greater than the second duty ratio.
Optionally, the storage unit 400 may be located in the display driving chip, or may also be a memory Flash, that is, the first group of parameter values and the second group of parameter values may be burned in the display driving chip, or may also be stored in the memory Flash, and fig. 5 schematically illustrates only the storage unit 400 as the memory Flash, as shown in fig. 4, the first duty ratio is greater than the second duty ratio, where the first duty ratio is a group of duty ratio values, and the second duty ratio is also a group of duty ratio values, such as a curve in fig. 4, where the first group of parameter values corresponds to the first duty ratio, the second group of parameter values corresponds to the second duty ratio, the parameter value corresponding to the first duty ratio is long in light emitting time, a value (e.g., vdata) corresponding to an adjustment current in parameter values of the Demura table is small, the light emitting intensity of the display panel 100 is small, and the luminance of the display panel 100 determined according to the light emitting intensity and the light emitting time is wholly unchanged, so as to improve the luminance uniformity of the display panel 100; the second duty is smaller than a set of parameter values, the light emitting time is short, the value (e.g., vdata) corresponding to the adjustment current among the parameter values of the Demura table is large, the light emitting intensity of the display panel 100 is large, the luminance of the display panel 100 determined according to the light emitting intensity and the light emitting time is not changed as a whole, and the luminance uniformity of the display panel 100 is improved.
In some alternative embodiments, with reference to fig. 1, the image processing unit 200 determines that the brightness unevenness of the display image is of a first level or a second level, and when the brightness unevenness is of the first level, calls a first set of parameter values corresponding to a first duty ratio to adjust the brightness of the display image of the display panel 100; and when the uneven brightness degree is judged to be 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, and adjusting the brightness of the display image of the display panel 100.
It is understood that the first level may be a light level, the second level may be a severe level, and the image processing unit 200 determines that the brightness unevenness of the display image is the first level, that is, the Mura is a light level, and invokes a first set of parameter values corresponding to the first duty ratio to adjust the brightness of the display image of the display panel 100; the image processing unit 200 determines that the brightness unevenness of the display image is of the second level, that is, mura is severe, and calls a second set of parameter values corresponding to the second duty ratio to adjust the brightness of the display image of the display panel 100.
Specifically, the image processing unit 200 determines the degree of the brightness nonuniformity of the display image in the low-brightness state, that is, determines the severity of Mura, and the compensation unit 300 retrieves the parameter values corresponding to the duty ratios of the different light emission control signals according to the degree of the brightness nonuniformity of the display image, and 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, and the brightness difference of the sub-pixel P is small, at this time, a set of parameter values corresponding to a first duty ratio with a large duty ratio can be retrieved, the light emission time is long, the value (such as Vdata) corresponding to the 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 not changed as a whole, and the brightness uniformity of the display panel 100 is improved; if the Mura is severe in a low-brightness state, that is, the current difference is large, and the luminance difference of the sub-pixel P is large, a set of parameter values corresponding to the second duty ratio with a small duty ratio may be called, the light emitting time is short, the value (for example, vdata) corresponding to the adjustment current in the parameter values of the Demura table is large, the light emitting intensity of the display panel 100 is large, the luminance of the display panel 100 determined according to the light emitting intensity and the light emitting time is not changed 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 for brightness compensation according to whether the brightness unevenness degree of the display image is the first level or the second level, 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 the driving method of the display device provided by the present invention, and the driving method in fig. 6 includes:
s101: acquiring a display image of a display panel;
s102: judging the uneven brightness degree of the displayed image, wherein the uneven brightness degree comprises a first level and a second level, and the first level is smaller than the second level;
s103: when the degree of the uneven brightness is judged to be the first level, calling a first group of parameter values corresponding to the first duty ratio to regulate the brightness of the display image of the display panel; and when the non-uniform brightness degree is judged to be the second level, calling 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 adjusting the brightness of the display image of the display panel.
Specifically, S101: the display image of the display panel is obtained by obtaining the display image in the low luminance state of the key luminance value, for example, 2nit, 5nit, 10nit, 26nit, 90nit, and 110nit, and the luminance image between 2nit and 5nit, the luminance image between 5nit and 10nit, the luminance image between 10nit and 26nit, the luminance image between 26nit and 90nit, and the luminance image between 90nit and 110nit may be calculated by using a linear difference, and the key luminance value is not specifically limited here.
Step S102: the method comprises the steps of judging the uneven brightness degree of a displayed image, wherein the uneven brightness degree comprises a first level and a second level, the first level is smaller than the second level, the mode of judging the uneven brightness degree is not specifically limited, the first level can indicate that the uneven brightness degree is slight, and the second level indicates that the uneven brightness degree is serious.
Step S103: when the uneven brightness degree is judged to be the first level, calling a first group of parameter values corresponding to the first duty ratio to adjust the brightness of the display image of the display panel; when the brightness unevenness degree is judged to be a second level, calling 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 regulating the brightness of the display image of the display panel, specifically, judging whether the brightness unevenness degree of the display image in a low-brightness state is a first level or a second level, namely judging the severity of Mura, if the brightness unevenness degree of the display image in the low-brightness state is slight, namely the current difference is small, the sub-pixel brightness difference is small, then calling a first group of parameter values corresponding to the first duty ratio with large duty ratio, wherein the light-emitting time is long, the value (such as Vdata) corresponding to the regulated current in the parameter values of the Demura table is small, the light-emitting intensity of the display panel is small, the brightness of the display panel is determined to be unchanged as a whole according to the light-emitting intensity and the light-emitting time, and the brightness uniformity of the display panel is improved; if the Mura degree is more serious in a low-brightness state, namely the current difference is larger, and the sub-pixel brightness difference is larger, a second group of parameter values corresponding to a second duty ratio with a smaller duty ratio can be called, the light-emitting time is short, the value (such as Vdata) corresponding to the regulated current in the parameter values of the Demura table is larger, the light-emitting intensity of the display panel is larger, the brightness of the display panel determined according to the light-emitting intensity and the light-emitting time is not changed integrally, and the brightness uniformity of the display panel is improved.
According to the invention, in a low-brightness state, different parameter values are called for brightness compensation according to whether the brightness unevenness degree of the display image is a first level (Mura is slight) or a second level (Mura is serious), 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 the luminance of the sub-pixels and a luminance compensation parameter, for example, the average luminance of the display image is 50nit, a difference value between the luminance of each sub-pixel in the display image and the average luminance needs to be calculated, the luminance difference value needs to be converted into a gray-scale difference value, and then the gray-scale difference value, i.e., offset, needs to be recorded in the storage unit, and a voltage value, e.g., the data voltage Vdata, needed when the luminance of each sub-pixel is adjusted to the average luminance needs to be stored. 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 adjusted 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 guaranteed to be 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, the light-emitting intensity adjusted by the second gamma value and the second brightness compensation parameter value is large, and the whole light-emitting brightness of the display panel is guaranteed to be unchanged.
In some alternative embodiments, referring to fig. 7, fig. 8, and fig. 9, fig. 7 is a flowchart of a method for determining a degree of luminance unevenness of a display image according to the present invention, fig. 8 is a histogram of a distribution of compensation values, and fig. 9 is another histogram of a distribution of compensation values, where determining the degree of luminance unevenness of the display image includes:
s201: setting an average brightness value of a display image;
s202: acquiring the brightness of each sub-pixel in a 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 scale difference value;
s203: acquiring gray scale difference distribution of all sub-pixels;
s204: when the gray scale difference value is larger than a first preset threshold value, extracting the gray scale difference value, calculating the percentage of all gray scale difference values exceeding the first preset threshold value, and judging the uneven brightness degree according to the percentage.
Specifically, step S201: setting an average brightness value of the display image, where the average brightness value of the display image is to select one of the display brightnesses, for example, the display image with the average brightness of 32nit may be selected as a basis, and the display images corresponding to other brightnesses may be calculated according to a linear difference method, where the average brightness value of the set display image is not specifically limited, and may be, optionally, 2nit, 10nit, 26nit, 135nit, and the like.
Step S202: acquiring the brightness of each sub-pixel in the display image, calculating the brightness difference between the brightness of each sub-pixel and the average brightness value, converting the brightness difference into a gray scale difference, further acquiring the brightness of each sub-pixel, such as the brightness of the sub-pixel is 19nit, 20nit, 19nit, 23nit, 28nit, 26nit, 30nit \8230; \8230, etc., and the set average brightness value is 26nit, the brightness difference values are 7nit, 6nit, 7nit, 3nit, 2nit, 0, 4nit \8230 \ 8230;, the brightness difference values are converted into gray-scale difference values, for example, 7, 6, 7, 3, 2, 0, -4 \8230: \8230, although this is only an illustrative example and is not a limitation to the actual product.
Step S203: the gray scale difference distributions of all the sub-pixels are obtained as shown in fig. 8 and 9, which are bar charts of the gray scale difference distributions, for example, the gray scale differences are 7, 6, 7, 3, 2, 0, -4 \8230; \8230, and schematically illustrated when the gray scale difference is 7, if the number of the sub-pixels is 300 ten thousand, and the number of the gray scale differences is 5000, the sub-pixel occupation ratio of the gray scale difference 7 is 5000/300 ten thousand, i.e., 0.16%.
Step S204: when the gray scale difference value is larger than a first preset threshold value, the gray scale difference value is extracted, the percentage of all gray scale difference values exceeding the first preset threshold value is calculated, and the degree of uneven brightness is judged according to the percentage. Where the first predetermined threshold is predetermined, in some alternative embodiments, continuing with reference to FIGS. 8 and 9, the first predetermined threshold is n,2 ≦ n ≦ 4. The first preset threshold n in the present invention may be 2, 3, or 4, and is not particularly limited herein. For example, if the gray scale difference is set to be less than or equal to-3 and less than or equal to 3, then the brightness difference of the sub-pixels is considered to be less, that is, the Mura is slight, but if the gray scale difference is greater than 3 or less than-3, then the gray scale difference is greater, then the gray scale difference is extracted, the percentage sum of all the gray scale differences exceeding the first preset threshold is calculated, the severity of the Mura is determined according to the magnitude of the percentage sum, if the percentage sum is smaller, the Mura is slight, and if the percentage sum is greater, the severity of the Mura is severe.
In some alternative embodiments, with continued reference to fig. 8 and 9, the percentage is less than a second predetermined threshold, the degree of brightness non-uniformity is a first level, the percentage is greater than the second predetermined threshold, and the degree of brightness non-uniformity is a second level.
In some alternative embodiments, the second predetermined 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 the gray-scale difference values in all sub-pixels smaller than-3 in fig. 8 is 0.42% and smaller than 10%, so the degree of the brightness unevenness is considered as the first level, i.e. the Mura is slight. The percentage of gray scale difference values in fig. 9 for all sub-pixels less than-3 are 14.2% and greater than 10% in total, so the degree of brightness unevenness is considered to be the second level, i.e., mura is severe.
If the Mura degree is the first level in a low-brightness state, namely the current difference is small, the sub-pixel brightness difference is small, a group of parameter values with large duty ratio can be called, the light-emitting time is long, the value (such as Vdata) of the corresponding regulating current in the parameter values of the Demura table is small, the light-emitting intensity of the display panel is small, the brightness of the display panel determined according to the light-emitting intensity and the light-emitting time is not changed integrally, and the brightness uniformity of the display panel is improved; if the Mura degree is the second level in the low-brightness state, namely the current difference is large, the sub-pixel brightness difference is large, a group of parameter values with small duty ratio can be called at the moment, the light-emitting time is short, the value (such as Vdata) corresponding to the regulated current in the parameter values of the Demura table is large, the light-emitting intensity of the display panel is large, the brightness of the display panel determined according to the light-emitting intensity and the light-emitting time is not changed as a whole, and the brightness uniformity of the display panel is improved.
Referring to fig. 10, fig. 10 is a flow chart showing real-time display of a display device according to the present invention, fig. 10 shows that a flag bit is first read, where the flag bit has no practical meaning and is only used as a mark, and then it is determined whether the percentage sum of gray level difference values greater than 3 is greater than 10%, if it is less than 10%, a first gamma value corresponding to a first duty ratio and a first brightness compensation parameter value are retrieved, and if it is greater than 10%, a second gamma value corresponding to a second duty ratio and a second brightness compensation parameter value are retrieved, and a display panel performs display.
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 uneven brightness degree of a display image in a low-brightness state, namely judges the severity degree of Mura, the compensation unit calls parameter values corresponding to duty ratios of different light-emitting control signals according to the uneven brightness degree of the display image to perform brightness compensation on the display image, if the Mura degree is slight in the low-brightness state, namely the current difference is small, the brightness difference of sub-pixels is small, a group of parameter values with large duty ratios can be called at the moment, the light-emitting time is long, the numerical values (such as Vdata) corresponding to the regulated current in the parameter values are small, the light-emitting intensity of the display panel is small, the brightness of the display panel determined according to the light-emitting intensity and the light-emitting time is not changed as a whole, and the brightness uniformity of the display panel is improved; if the Mura degree is serious in a low-brightness state, namely the current difference is large, the sub-pixel brightness difference is large, a group of parameter values with small duty ratio can be called, the light-emitting time is short, the numerical value (such as Vdata) corresponding to the regulated current in the parameter values is large, the light-emitting intensity of the display panel is large, the brightness of the display panel determined according to the light-emitting intensity and the light-emitting time is not changed integrally, and the brightness uniformity of the display panel is improved. According to the invention, under the low-brightness state, the brightness compensation is carried out according to different degrees of the uneven brightness of the displayed image, so that the display uniformity under the low-brightness state is improved.
Although some specific embodiments of the present invention have been described in detail by way of example, it should be understood 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 (10)
1. A display device, comprising:
a display panel including 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 uneven brightness degree of the display image;
and the compensation unit is coupled with the image processing unit and used for calling parameter values corresponding to duty ratios of different light-emitting control signals according to the uneven brightness of the display image so as to carry out brightness compensation on the display image.
2. The display device according to claim 1, further comprising a storage unit coupled to the compensation unit, the storage unit comprising a first set of parameter values and a second set of parameter values, the first set of parameter values corresponding to a first duty cycle and the second set of parameter values corresponding to a second duty cycle, the first duty cycle being greater than the second duty cycle.
3. The display device according to claim 1, wherein the image processing unit determines whether the degree of the display image luminance unevenness is a first level or a second level, the first level being smaller than the second level.
4. The display device according to claim 3, wherein when it is determined that the degree of the brightness unevenness is a first level, a first set of parameter values corresponding to a first duty ratio is called to adjust brightness of the display image of the display panel;
and calling a second group of parameter values corresponding to a second duty ratio when the uneven brightness degree is judged to be a second level, wherein the first duty ratio is larger than the second duty ratio, and adjusting the brightness of the display image of the display panel.
5. A method of driving a display device, comprising:
acquiring a display image of a display panel;
judging the uneven brightness degree of the display image, wherein the uneven brightness degree comprises a first level and a second level, and the first level is smaller than the second level;
when the brightness unevenness degree is judged to be the first level, calling a first group of parameter values corresponding to a first duty ratio to regulate the brightness of the display image of the display panel; and calling a second group of parameter values corresponding to a second duty ratio when the uneven brightness degree is judged to be a second level, wherein the first duty ratio is larger than the second duty ratio, and adjusting the brightness of the display image of the display panel.
6. The method of driving a display device according to claim 5, 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.
7. The method for driving a display device according to claim 5, wherein the determining the degree of the display image luminance unevenness includes:
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 scale difference value;
obtaining gray scale difference value distribution of all sub-pixels;
when the gray scale difference value is larger than a first preset threshold value, extracting the gray scale difference value, calculating the percentage of all gray scale difference values exceeding the first preset threshold value, and judging the uneven brightness degree according to the percentage.
8. The method for driving a display device according to claim 7, wherein the percentage is smaller than a second predetermined threshold, and the degree of the luminance nonuniformity is a first level, and wherein the percentage is larger than the second predetermined threshold, and the degree of the luminance nonuniformity is a second level.
9. The method according to claim 7, wherein the first predetermined threshold is n,2 ≦ n ≦ 4.
10. The method according to claim 7, wherein the second predetermined threshold is m, and wherein m is greater than or equal to 10% and less than or equal to 15%.
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