TWI773429B - Display driving device with de-burn-in and display device having the same - Google Patents

Abstract

A display driving device includes a driving unit and a de-burn-in device. The driving unit drives a display panel to display a display frame on the display panel. The de-burn-in device accumulates the emission time of each sub-pixel unit in a CUP area of the display panel and, according to the accumulated emission time, looks up the compensation gain of each sub-pixel unit in the CUP area to compensate for the degraded brightness of the CUP area.

Description

Display driving device with burn-in compensation and display device including the same

The present invention relates to the technical field of display panels, and more particularly, to a display driving device with burn-in compensation and a display device including the same.

Currently, the burn-in compensation (de-burn-in) of a display panel such as an organic light emitting diode (OLED) mainly uses an electrical compensation method, and the electrical compensation needs to add a current to the pixel circuit structure of the display panel. The sensing circuit or voltage sensing circuit, with the cooperation of the display driving circuit, actively detects the current-voltage characteristics of the thin film transistors or the current-voltage characteristics of the light-emitting diodes of each sub-pixel of the display panel, so as to detect the current-voltage characteristics of the thin-film transistors of each sub-pixel of the display panel. The difference between the sensed current or voltage and the characteristics of the display panel when it leaves the factory is calculated and compensated in the display driving circuit.

Therefore, to compensate the burn-in phenomenon of the display panel by the aforesaid conventional electrical compensation, the pixel circuit structure of the display panel needs to be modified, and a large amount of information including the factory information of each sub-pixel of the display panel and the required compensation value needs to be stored. , resulting in excessively high computation and memory requirements for the display drive circuit, and this burn mark compensation process is aimed at the entire display panel, and cannot arbitrarily select local areas for sensing and compensation. Therefore, the achievability and mass production are Sex is not good, and can not meet the actual needs.

Furthermore, in the existing mobile devices such as mobile phones or tablets, in order to realize the function of taking a selfie with a full screen, the display panel of the mobile device adopts an under-screen camera (Camera Under Panel, CUP) design, and in order to increase the transmittance of the camera without affecting the display effect, the display panel of the existing mobile device is to reduce the pixel density of the display panel directly above the camera or reduce the sub-pixel size to increase the panel opening of the CUP area. rate, so that the camera can have enough light to take pictures.

However, increasing the aperture ratio also reduces the brightness of the CUP area. In order to make the entire panel display the same visual effect when displaying images, and prevent users from feeling that the display in the CUP area is abnormally dark, a comparison is generally applied in the CUP area. Bright gamma (Gamma) setting, in the way of increasing the pixel current, the brightness of the pixels in the CUP area is increased, and the brightness is adjusted to be close to the brightness of the normal display area. However, since the luminescent material of the display panel has a certain lifespan, the method of increasing the brightness will lead to increased material loss and shorten the lifespan of the pixels.

Therefore, there are still many deficiencies in the design of the conventional display panel, and it is necessary to improve it.

The main purpose of the present invention is to provide a display driving device with burn-in compensation and a display device including the display driving device, which can effectively solve the CUP problem without consuming less hardware resources and without changing the circuit of the display panel. Burn-in phenomenon caused by pixel burn-in of the area or the whole panel.

According to a feature of the present invention, a display driving device is provided, comprising: a driving unit driving a display panel to display a display frame on the display panel, wherein the display panel has a plurality of pixel units, each A pixel unit includes at least one specific The sub-pixel unit of the color, and the display panel further has a camera area under the screen; and a burn-in compensation device for accumulating the light-emitting time of each sub-pixel unit in the camera area under the screen, and according to the accumulated light-emitting time to find out the compensation gain value of each sub-pixel unit in the camera area under the screen, so as to compensate the decayed luminous brightness of the camera area under the screen.

According to another feature of the present invention, a display driving device is provided, comprising: a driving unit driving a display panel to display a display frame on the display panel, wherein the display panel has a plurality of pixel units, Each pixel unit includes at least one sub-pixel unit of a specific color; and a burn mark compensation device for accumulating the light-emitting time of each sub-pixel unit of the display panel, and sampling an accumulated light-emitting time for all the sub-pixel units of the display panel The average value of the accumulated light-emitting time of the pixel units, and the compensation gain value of each sub-pixel unit of the display panel is found according to the accumulated light-emitting time, so as to compensate the decayed light-emitting brightness of the display panel.

The present invention also proposes a display device including the aforementioned display driving device.

The above overview and the following detailed description are exemplary in nature, and are intended to further illustrate the scope of the present invention, and other objects and advantages of the present invention will be explained in the following descriptions and drawings.

10: Display panel

11: Pixel unit

101: Sub-pixel unit

12: Camera under the screen (CUP) area

20: Display driver

30: Gamma Device

40: show frame

50: Burning mark compensation device

60: Drive unit

51: Cumulative processing of light-emitting time

52: Downsampling

53: Data storage processing

531: memory

54: Burn mark compensation processing

541: Gain Lookup Table

FIG. 1 shows a display device according to an embodiment of the present invention.

FIG. 2 shows the structure of a burn mark compensation device according to an embodiment of the present invention and a process for compensating for fading luminous brightness.

FIG. 3 schematically shows the accumulated light-emitting time information of the CUP area.

FIG. 4 schematically shows the accumulated light-emitting time information of the CUP region after down-sampling.

FIG. 5 shows a display device according to another embodiment of the present invention.

FIG. 6 shows the structure of the burn mark compensation device according to another embodiment of the present invention and the process of compensating for fading luminous brightness.

FIG. 7 schematically shows the accumulated light-emitting time information of the entire display panel.

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention, and are not used to limit the present invention.

FIG. 1 shows a display device according to an embodiment of the present invention, which includes a display panel 10 and a display driving device 20 . The display driving device 20 has a driving unit 60 , a gamma device 30 , and a burn mark compensation device 50 . , wherein the driving unit 60 is used to drive the display panel 10 and use the gamma device 30 to convert the display data value of the display frame 40 into a gamma voltage to display the display frame 40 on the display panel 10 , and the display panel 10 is in the The structure of the display surface includes a plurality of pixel units 11 arranged in rows and columns, and each pixel unit 11 includes at least one sub-pixel unit 101 of a specific color. In an embodiment and the following description of the present invention, the display panel 10 Each pixel unit 11 includes a red (R) sub-pixel unit 101 , a green (G) sub-pixel unit 101 and a blue (B) sub-pixel unit 101 , that is, the pixel units 11 of the display panel 10 display The color of the pixel is composed of three colors of R/G/B. However, the present invention is not limited to the arrangement and combination of the sub-pixels. In other embodiments, the sub-pixel units in the above-mentioned pixel units may also be in different orders. arrangement of combinations. and on the display panel 10 further has an under-screen camera (Camera Under Panel, CUP) area 12 , that is, a camera is embedded under the display panel 10 in the CUP area 12 , and compared with the rest of the display panel 10 , the CUP area is 12 has a sub-pixel unit 101 with a lower pixel density or a smaller sub-pixel size.

Since the sub-pixel units 101 in the CUP area 12 are over-used, the luminance attenuation will be more severe than that of the sub-pixel units 101 in the remaining areas of the display panel 10, resulting in a drop in luminance and causing burn-in. Therefore, the present invention compensates for the burn-in mark. The device 50 accumulates the light-emitting time of the sub-pixel units 101 in the CUP area 12 , and finds the compensation gain value of the sub-pixel units 101 in the CUP area 12 according to the accumulated light-emitting time to compensate the decayed light-emitting brightness of the CUP area 12 . The CUP area 12 shown in FIG. 1 may also be any position on the panel 10 , and is not limited to the central position of the panel 10 .

FIG. 2 shows the structure of the aforementioned burn mark compensation device 50 and the process of compensating for the decayed luminous intensity. Wherein, in the light emission time accumulation process 51, when a display frame 40 is displayed, according to the image content displayed in the CUP area 12, for each color, the light emission time of each sub-pixel unit 101 in the CUP area 12 is accumulated ( emission time), wherein, the light-emitting time of a sub-pixel unit 101 is calculated according to its display linear grayscale value, display brightness value, and temperature value, more specifically, the light-emitting time of the sub-pixel unit 101 is calculated as follows The formula is obtained: Emission_time=linear_scale. dbv. temperature, where Emission_time is the light-emitting time of the sub-pixel unit 101 when a display frame 40 is displayed; linear_scale is the linear grayscale value of the image content displayed by the sub-pixel unit 101 , and the linear grayscale value is the display grayscale value Gamma power, that is, linear_scale=scale ^Gamma , where scale is the display grayscale value, for example, in 8-bit color depth display, the display grayscale value is 0~255, and Gamma is the luminance coefficient, such as 2.2; dbv is the display brightness value of the sub-pixel unit 101 , and dbv=DBV/2 ⁿ , where DBV represents the overall brightness, and n represents the brightness depth, and the calculated range of dbv is 0~1; temperature is the sub-pixel unit 101 The temperature value of , among which, the actual temperature is 50°C~70°C, the corresponding temperature value is 0~2.2.

Therefore, whenever a display frame 40 is displayed, the emitting time of each sub-pixel unit 101 in the CUP area 12 is accumulated, namely: AET=AET+Emission_time, wherein AET is the accumulated emitting time of the sub-pixel unit 101 , and its initial value is 0. And in order to comply with the arithmetic processing of the display driving device 20, the accumulated light-emitting time AET can be formulated, for example, so that the accumulated value is rounded up to 1 unit every 256, and every 60 units is rounded to 1 second, and every 60 seconds is rounded up. It is 1 minute (minute), and every 60 minutes rounds up to 1 hour (hour). After the above-mentioned light emission time accumulation processing 51, the accumulated light emission time information of the CUP area 12 can be obtained, that is, as shown in FIG. The accumulated light-emitting time AET of each sub-pixel unit 101 of the CUP area 12 is .

In the aforementioned light emission time accumulation process 51, each sub-pixel unit 101 in the CPU region 12 needs to accumulate light emission time, which may result in a huge amount of data. Therefore, in the downsampling process 52, optionally, for For each color, down sampling is performed on the accumulated light-emitting time AET of the sub-pixel units 101 in the CUP area 12, so that the multiple sub-pixel units 101 only sample one accumulated light-emitting time AET for the multiple sub-pixel units 101. The average value of the accumulated light-emitting time AET is used to reduce the amount of data. For example, as shown in FIG. 4 , it is possible to sample only one accumulated light-emitting time AET of 4 ( =2x2) sub-pixel single The average value of the accumulated light-emitting time AET of the element 101 is used to obtain the accumulated light-emitting time information of the CUP area 12 after downsampling. Accordingly, the amount of data to be stored can be effectively reduced. However, it should be noted that when the storage space is When sufficient, this downsampling process 52 is not required.

Next, in the data storage process 53, the accumulated light-emitting time information of the CUP area 12 obtained by the above-mentioned light-emitting time accumulation process 51 or the accumulated light-emitting time information of the CUP area 12 obtained after the down-sampling process 52 is stored in the memory. In the bank 531, for example, it is stored in a static random access memory (SRAM), and in order to prevent the data of the static random access memory from being cleared when the power is turned off abnormally, the accumulated data of the stored CUP area 12 can be accumulated from time to time. The light-emitting time information is written into the flash memory (Flash) to ensure the security of the data.

Further, in the burn mark compensation process 54, for each color, a gain look-up table 541 is pre-established for searching the compensation gain value of the sub-pixel unit 101 of the CPU area 12. As shown in the figure, the gain look-up table 541 includes accumulated The luminous time item (AET) and the corresponding compensation gain value item (gain) of the The compensation gain value in the compensation gain value item (gain).

Therefore, the burn mark compensation process 54 uses the pre-established gain look-up table 541 to look up the table. According to the accumulated light-emitting time AET of the sub-pixel units 101 in the CUP area 12, the gain look-up table 541 can be used to calculate the calculation by interpolation. The compensation gain value of the sub-pixel unit 101 is used to perform burn mark compensation: R'=R. R_gain, G'=G. G_gain, B'=B. B_gain, where R/G/B is the original red/green/blue display data value to be displayed by the red/green/blue sub-pixel unit 101, and R_gain/G_gain/B_gain is the red/green/blue sub-pixel found The compensation gain value of the pixel unit 101 , R′/G′/B′ is the post-compensated red/green/blue display data value displayed by the red/green/blue sub-pixel unit 101 . Among them, the compensated display data value R'/G'/B' may be greater than the original display data value R/G/B to achieve the purpose of brightness compensation. Accordingly, when driving the CUP area 12 of the display panel 10 , the driving unit 60 displays an image on the CUP area 12 of the display panel 10 according to the gamma device 30 converting the compensated display data value into a gamma voltage.

Since the compensated display data value is larger than the original display data value, in order to achieve effective brightness compensation, the range of the original display data value can be extended through a special extended gamma structure and correspond to the correct gamma voltage, according to The brightness is increased to achieve the purpose of compensation. This extended gamma structure can be found in the patent application No. 108146468 "Extended gamma device for display panel and display device including the same" filed by the same applicant, which is incorporated herein by reference. .

FIG. 5 shows a display device according to another embodiment of the present invention, the structure of which is similar to that of the previous embodiment, but the burn mark compensation device 50 compensates the decayed luminance of the entire display panel 10 . FIG. 6 shows the structure of the aforementioned burn mark compensation device 50 and the process of compensating the decayed luminous brightness. In the luminous time accumulation process 51 , when a display frame 40 is displayed, the image displayed on the display panel 10 is instantly displayed. Content, for each color, the emission time (emission time) of each sub-pixel unit 101 of the display panel 10 is accumulated to obtain the accumulated emission time AET of each sub-pixel unit 101. Therefore, for each color, the accumulated light-emitting time AET of all the sub-pixel units 101 of the display panel 10 is only sampled for one accumulated light-emitting time AET as the accumulated light-emitting time AET of all the sub-pixel units 101 The average value of the light-emitting time AET is shown in FIG. 7 . Therefore, the amount of accumulated light-emitting time information data of the entire display panel 10 obtained by the light-emitting time accumulation process 51 is extremely small. Therefore, in the data storage process 53, the required static random The storage space of access memory (SRAM) and flash memory (Flash) is also very small.

Furthermore, in the burn mark compensation process 54, for each color, a gain look-up table 541 is pre-established for searching the compensation gain value of the sub-pixel unit 101 of the display panel 10. The gain look-up table 541 is the same as the previous one. Examples are not described in detail.

Therefore, the burn mark compensation process 54 uses the pre-established gain look-up table 541 to look up the table. According to the accumulated light-emitting time AET of the overall display panel 10, the sub-pixel unit 101 can be calculated from the gain look-up table 541 by means of interpolation. The original R/G/B display data value to be displayed is compensated with the compensation gain value to become the compensated R'/G'/B' display data value for burn mark compensation, so as to achieve the purpose of brightness compensation . Accordingly, when the display panel 10 is driven, the driving unit 60 displays an image on the display panel 10 according to the gamma device 30 converting the compensated display data value into a gamma voltage.

It can be seen from the above description that the present invention performs burn mark compensation by accumulating light-emitting time, which can effectively solve pixel burn marks in the CUP area or the entire panel without consuming less hardware resources and without changing the circuit of the display panel. The resulting imprinting phenomenon.

The above-mentioned embodiments are only examples for convenience of description, and the scope of the claims claimed in the present invention should be based on the scope of the patent application, rather than being limited to the above-mentioned embodiments.

10: Display panel

11: Pixel unit

101: Sub-pixel unit

12: Camera under the screen (CUP) area

20: Display driver

30: Gamma Device

40: show frame

50: Burning mark compensation device

60: Drive unit

Claims (9)

A display driving device, comprising: a driving unit for driving a display panel to display a display frame on the display panel, wherein the display panel has a plurality of pixel units, and each pixel unit includes at least one pixel of a specific color. a sub-pixel unit, and the display panel further has a camera area under the screen; and a burn-in compensation device for accumulating the light-emitting time of each sub-pixel unit in the camera area under the screen, and searching for the light-emitting time according to the accumulated light-emitting time The compensation gain value of each sub-pixel unit in the camera area under the screen is obtained to compensate the decayed luminous brightness of the camera area under the screen, wherein the light-emitting time of a sub-pixel unit is obtained by the following formula: Emission_time=linear_scale. dbv. temperature; among them, Emission_time is the light-emitting time of the sub-pixel unit when a display frame is displayed; linear_scale is the linear grayscale value of the image content displayed by the sub-pixel unit; dbv is the display brightness value of the sub-pixel unit; temperature is the sub-pixel unit The temperature value of the unit. The display driving device according to claim 1, wherein the burn-in compensation device performs a down-sampling process, so that a plurality of sub-pixel units only sample an accumulated light-emitting time which is an average of the accumulated light-emitting time of the plurality of sub-pixel units value. The display driving device as claimed in claim 1 or 2, wherein the burn-in compensation device stores the accumulated light-emitting time of the camera area under the screen in a static random access memory, and the camera area under the screen is not fixed from time to time The accumulated light-emitting time is written into a flash memory. The display driving device of claim 1, wherein the burn-in compensation device has a preset gain look-up table for finding the compensation gain value of the sub-pixel unit in the camera area under the screen according to the accumulated light-emitting time. A display device, comprising: a display panel and the display driving device according to claim 1. A display driving device, comprising: a driving unit for driving a display panel to display a display frame on the display panel, wherein the display panel has a plurality of pixel units, and each pixel unit includes at least one pixel of a specific color. a sub-pixel unit; and a burn mark compensation device for accumulating the light-emitting time of each sub-pixel unit of the display panel, and sampling an accumulated light-emitting time is the average value of the accumulated light-emitting time of all the sub-pixel units of the display panel , and find out the compensation gain value of each sub-pixel unit of the display panel according to the accumulated light-emitting time to compensate the decayed light-emitting brightness of the display panel, wherein the light-emitting time of a sub-pixel unit is calculated by the following formula Got: Emission_time=linear_scale. dbv. temperature; among them, Emission_time is the light-emitting time of the sub-pixel unit when a display frame is displayed; linear_scale is the linear grayscale value of the image content displayed by the sub-pixel unit; dbv is the display brightness value of the sub-pixel unit; temperature is the sub-pixel unit The temperature value of the unit. The display driving device as claimed in claim 6, wherein the burn mark compensation device stores the accumulated light-emitting time of the display panel in a static random access memory, and writes the accumulated light-emitting time of the display panel from time to time in a flash memory. The display driving device according to claim 6, wherein the burn mark compensation device has a preset gain look-up table for finding the compensation gain value of the sub-pixel unit of the display panel according to the accumulated light-emitting time. A display device, comprising: a display panel and the display driving device according to claim 6.

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