TWI692893B - Intelligent group picture compensation method and display device using the same - Google Patents

Abstract

A smart group picture compensation method, comprising: performing a brightness evaluation operation on a global picture image of a display to determine at least one area requiring compensation and at least one area requiring no compensation; and performing one for each of the areas requiring compensation The block division operation is to determine the number of a picture block and a corresponding compensation coefficient according to the brightness uniformity of each of the compensation areas.

Description

Intelligent group picture compensation method and display device using the same

The invention relates to a picture compensation method of a display device, in particular to a smart group picture compensation method used in a display device.

In the field of liquid crystal display manufacturing, due to the limitations of process technology, after the final manufacturing of the liquid crystal display, it is easy for local display chromaticity and brightness unevenness, which is called Mura. Generally speaking, the Mura phenomenon can be compensated by the picture compensation (De-mura) scheme.

At present, the design of organic light emitting diode (OLED) panels generally uses low-temperature polysilicon thin film transistors (LTPS TFT) and oxide thin film transistors (Oxide TFT) technology. Compared with ordinary amorphous silicon thin film transistors (amorphous-Si TFT), LTPS TFT and Oxide TFT have higher mobility and more stable characteristics, and are more suitable for application in active matrix organic light emitting diodes (AMOLED) The display of the panel.

The driving current I of the OLED is determined by the TFT, I = kC _ox (V _gs -V _th ) ² (1+λV _ds ), where k is related to the mobility of the TFT, C _ox is the capacitance constant of the oxide layer, and V _th is A threshold voltage, V _gs is a gate-source voltage, V _ds is a drain-source voltage, λ is a channel length modulation parameter, and V _gs and V _{ds are} related to the power supply voltage and the OLED driving voltage.

As can be seen from the above, the parameters that affect the magnitude of the driving current I include the TFT mobility, the threshold voltage, the driving voltage of the OLED, and the magnitude of the power supply voltage.

In addition, LTPS TFTs are mostly used in small and medium-sized applications, while Oxide TFTs are mostly used in large-size applications. This is because the mobility of LTPS TFTs is larger, the device area is smaller, and it is more suitable for high-pixel inches. (PPI); Oxide TFT is more suitable for the production of large-size AMOLED panels on high-generation lines due to its better uniformity and manufacturing technology compatible with amorphous silicon thin film transistors.

But each of the above technologies has its own disadvantages. Due to the limitations of crystallization technology, LTPS TFTs fabricated on large-area glass substrates generally exhibit non-uniformity of electrical parameters such as threshold voltage and mobility at different positions, and this non-uniformity will be converted into OLED display The difference in current and brightness of the device is perceived by the human eye and produces the mura phenomenon; although the Oxide TFT has good uniformity, it is similar to the a-Si TFT. Under long-term pressure and high temperature, the threshold voltage Drift will occur, and during different display screens, the threshold drift of the TFTs in each part of the panel will also be different, resulting in differences in display brightness. Since this difference is related to the previously displayed image, it often appears as an afterimage phenomenon, also known as afterimage.

Therefore, in the existing process, whether it is LTPS TFT or Oxide TFT, there are problems of uniformity or stability, and related compensation technical solutions are required.

The current compensation technology scheme can be divided into an internal compensation scheme and an external compensation scheme. Among them, the internal compensation scheme generally compensates the threshold voltage and voltage decay in a pixel circuit, and the external compensation scheme generally compensates in a peripheral drive circuit.

Please refer to FIGS. 1 and 2 together, wherein FIG. 1 shows a circuit diagram of a conventional internal compensation scheme, wherein the circuit includes PMOS transistors 11-17, capacitors 18-19, and an organic light-emitting diode 20; and FIG. 2. It shows a working timing diagram of a driving cycle of the conventional internal compensation scheme of FIG. 1, wherein the driving cycle includes three working phases: reset, compensation, and lighting.

For the equivalent circuit of the conventional internal compensation scheme in FIG. 1 during the reset phase, please refer to FIG. 3a, where Gn-1 is low and Gn and EM are both high. At this time, an INIT voltage will pass through the PMOS transistor 11 and The PMOS transistor 12 resets/precharges the capacitor 18 and the capacitor 19 respectively; for the equivalent circuit of the conventional internal compensation scheme of FIG. 1 during the compensation stage, please refer to FIG. 3b, where Gn-1 and EM are due to the low potential Both are high potentials. At this time, a DATA voltage charges the capacitor 18 so that the lower potential of the capacitor 18 is equal to DATA-V _th ; and the equivalent circuit of the conventional internal compensation scheme of FIG. 1 during the light-emitting phase, please refer to FIG. 3c. Among them, because EM is low potential, Gn and Gn-1 are high potential, at this time PMOS transistor 17 works in the saturation region, and its current I = kC _ox (ELVDD-(DATA-V _th )-V _th ) ² = I = kC _ox (ELVDD-DATA) ² .

That is to say, the working idea of the conventional internal compensation scheme of FIG. 1 is to store the threshold voltage (Vth) of the PMOS transistor 17 in its gate-source voltage (V _gs ) in the compensation stage, because the The current is determined by V _gs -V _th , therefore, in the case where V _gs already contains V _th , the effect of V _th on the current can be canceled out to achieve current consistency. But in fact, due to the influence of parameter temporary storage and driving speed, V _th cannot be completely cancelled, that is to say, when the deviation of V _th exceeds a certain range (for example, V _th ≥ 0.5V), the consistency of the current cannot be ensured Therefore, the compensation range of the conventional internal compensation scheme in FIG. 1 is limited.

The general external compensation scheme is divided into optical extraction type and electrical extraction type according to the different data extraction methods. The optical extraction type refers to the method of extracting the brightness signal after the back panel is lit by the optical image sensing device (CCD) photography method The electrical extraction method refers to the electrical signals of TFT and OLED extracted by driving the sensor circuit of the chip. The method of optical extraction has the advantages of simple structure and flexible method, so it is widely used at this stage; and electrical extraction needs to add a detection circuit to the panel design, but it is currently at high PPI (pixels per inch; pixels per inch ) In the panel circuit, it is very difficult to add an additional detection circuit, so it is basically not applicable to the panel of the mobile phone.

Although the optical extraction type is widely used at this stage, the optical extraction type still has a problem that it takes too long to complete the compensation. Please refer to FIG. 4, which is a schematic diagram of an optical extraction compensation operation. As shown in FIG. 4, the optical extraction compensation operation includes: outputting the test image to the panel to be tested (step S10); the optical system capturing the brightness distribution in the panel (step S11); sub-pixel compensation modeling (step S12); Sub-pixel compensation model data compression (step S13); outputting the compressed data to an external flash memory 10; and a display panel driving chip 30 using a static random access memory 31 to store the data provided by the external flash memory 10 The compressed data uses a static random access memory 32 to store an input image, and an image processing unit 33 performs a compensation based on the data provided by the static random access memory 31 and the static random access memory 32 Work to produce a compensated image. In this optical extraction operation, the total amount of time it takes for each panel to complete screen compensation on the production line is the time it takes for the screen compensation data compression algorithm to add the compressed data to the flash memory in sequence Body (Flash) time. Since the current optical extraction operation uses fixed-size picture blocks, such as (4x4) picture blocks, the number of picture blocks on a panel can be calculated according to the picture block size. In addition, the data records are recorded sequentially according to a compensation coefficient for each picture block. Therefore, assuming there are 10,000 picture blocks on a panel, 10,000 compensation coefficients will be generated in the sub-pixel compensation model data compression (step S13), and these 10,000 compensation coefficients must be written to the external fast Flash memory 10.

That is to say, as the resolution increases, the number of blocks will increase significantly, and the increase in the number of blocks will increase the number of compensation coefficients generated by data compression and the time for writing these coefficients into the external flash memory 10, In this way, the operation time of the entire De-mura will greatly affect the output rate of the panel, thereby increasing the production cost.

In addition, De-mura's compensation technology adds additional cost, one is external flash memory 10, and the other is internal static random access memory 31. The higher the resolution, the larger the space required for the external flash memory 10 and the static random access memory 31, and this will greatly increase the cost of an OLED module.

For example, a high definition (HD) global picture image is divided into 10,000 picture blocks, while a ultra high definition (wide quad high definition; WQHD) global picture image may have 40,000 picture blocks The amount of memory required for the picture block has been expanded four times.

Therefore, in order to solve the above problems, a novel display picture compensation scheme is urgently needed in the art.

An object of the present invention is to disclose a smart grouping frame compensation method, which can reduce the space required by the memory, reduce the chip volume, reduce the cost, and greatly reduce the time required to write the frame compensation coefficient (De-mura).

Another object of the present invention is to disclose a display device that uses a smart grouping picture compensation method to perform picture compensation to reduce the space required by the memory, reduce the chip volume, reduce the cost, and greatly reduce the writing picture compensation coefficient. The time required.

To achieve the above purpose, a smart grouping picture compensation method is proposed, which includes:

Performing a brightness evaluation operation on a global picture image of a display to determine at least one area requiring compensation and at least one area requiring no compensation; and

A block division operation is performed on each of the compensation-required regions to determine a number of picture blocks and a corresponding compensation coefficient according to the brightness uniformity of each of the compensation-required regions.

In one embodiment, the smart grouped picture compensation method further includes storing the number of the picture blocks and the corresponding compensation coefficients of each of the areas to be compensated through a memory unit.

In one embodiment, the memory unit includes random storage memory or flash memory.

In one embodiment, the values of the corresponding compensation coefficients are divided into three values: slight compensation, moderate compensation, and heavy compensation.

In one embodiment, the display is a liquid crystal display, an OLED display, or a Micro-LED display.

In order to achieve the above object, the present invention further provides a display device that uses a smart grouping picture compensation method to perform picture compensation on a display. The method includes:

Performing a brightness evaluation operation on a global picture image of a display to determine at least one area requiring compensation and at least one area requiring no compensation; and

A block division operation is performed on each of the compensation-required regions to determine a number of picture blocks and a corresponding compensation coefficient according to the brightness uniformity of each of the compensation-required regions.

In one embodiment, the display device further includes a memory unit to store the number of the picture blocks and the corresponding compensation coefficients of each of the areas to be compensated.

In one embodiment, the memory unit includes random storage memory or flash memory.

In one embodiment, the values of the corresponding compensation coefficients are divided into three values: slight compensation, moderate compensation, and heavy compensation.

In one embodiment, the display is a liquid crystal display, an OLED display, or a Micro-LED display.

In order to enable your review committee to further understand the structure, features and purpose of the present invention, the drawings and detailed description of the preferred embodiments are attached as follows.

Please refer to FIG. 5 and FIG. 6 together, wherein FIG. 5 shows a flowchart of an embodiment of the smart packet frame compensation method of the present invention; and FIG. 6 shows a schematic block diagram of the smart packet frame compensation method of the present invention. As shown in FIG. 5, the method includes: performing a brightness evaluation operation on a global screen image of a display to determine at least one area requiring compensation and at least one area requiring no compensation (S101); and for each of the areas requiring compensation Each block division operation is performed to determine the number of a picture block and a corresponding compensation coefficient according to the brightness uniformity of each of the areas to be compensated (S102).

The method of FIG. 5 is applied to a display, which may be a liquid crystal display, an OLED (organic light emitting diode; organic light emitting diode) display, or a Micro-LED (micro light emitting diode; micro light emitting diode; )monitor. During operation, as shown in FIG. 6, the method first performs a brightness evaluation operation on a global screen image 100 of the display to determine two areas 220 requiring compensation and one area 300 requiring no compensation; then, for each Each of the compensation-needing regions 220 performs a block division operation to determine a number of picture blocks and a corresponding compensation coefficient according to the brightness uniformity of each of the compensation-needing regions.

Further, when the value of the compensation coefficient of a compensation area 220 is small and the area is large, the block division operation divides the compensation area with a larger picture block (such as but not limited to 32x32); If the value of the compensation coefficient of a compensation area 220 is large and the area is small, the block division operation will divide the dynamic area of the compensation area with a smaller picture block (such as but not limited to 4x4) for more detailed To compensate the area to be compensated. In addition, preferably, the value of the compensation coefficient can be divided into three values of slight compensation, moderate compensation and heavy compensation.

In addition, the method of FIG. 5 may further include storing the number of the picture blocks and the corresponding compensation coefficients of each area to be compensated through a memory unit, and the memory unit may be a flash memory or a random storage memory, etc. Common memory.

That is to say, the method of FIG. 5 determines a plurality of regions in the global screen image 100 according to the consistency range of brightness, and determines the numerical level of the compensation coefficient of each region according to the brightness. For example, if the compensation coefficient of an area is classified as level 0, it does not need to be compensated; if the compensation coefficient of an area is classified as level 1, it needs to be slightly compensated; if the compensation coefficient of an area is classified as 2 In the case of level, it needs to be moderately compensated; and if the compensation coefficient of an area is classified as level 3, it needs to be heavily compensated. In possible embodiments, the present invention may have fewer or more compensation coefficient levels.

After the classification is completed, the present invention uses the memory unit to mark the corresponding position of each picture block to accurately record the position of each picture block and the corresponding compensation coefficient.

For example, assume that the method of FIG. 5 determines that the global picture image 100 has 4 block clusters, the accuracy of the compensation coefficient is 1024 (10 bits), and the starting position has 4 (2 bits), The maximum block size is 1024 (10 bits), the maximum number of blocks in the picture is 128 (7 bits), and the 4 block clusters are classified as follows:

The first block group: 160x100, compensation coefficient level 0, screen block size 160x100;

The second block group: 100x50, compensation coefficient level 2, 8 picture blocks, and each picture block size is 25x25;

The third block group: 60*50, compensation coefficient level 3, 120 picture blocks, each picture block size is 5x5; and

The fourth block group: 160x50, compensation coefficient level 2, 20 picture blocks, and each picture block size is 16*25.

Then the required memory space is:

The first block group: 2 ² +2 ¹⁰ +0=1028;

The second block group: 8(2 ² +2 ³ +2 ¹⁰ )=8288;

The third block group: 120(2 ² +2 ⁷ +2 ¹⁰ )=138720; and

The fourth block group: 20(2 ² +2 ⁵ +2 ¹⁰ )=21200.

The total memory space required is:

1028+8288+138720+21200=169236.

In addition, the Mura caused by the current OLED manufacturing process is generally localized. Therefore, the compensation coefficients used in a large part of the blocks should be the same, and only some blocks need to be compensated with special compensation coefficients. Therefore, the amount of data and length at the beginning of the record will be less, and only 6 bits are enough. According to this, the present invention can further save memory space and operation time.

In addition, according to the above description, the present invention further provides a display device that utilizes the smart grouped picture compensation method to perform picture compensation on a display.

Therefore, with the method disclosed above, the present invention has the following advantages:

1. Reduce the memory space of the chip, reduce the chip volume, power consumption and cost.

2. Reduce the amount of space required for external storage flash memory to reduce costs.

3. Reducing the time required to write the compensation factor of the chip picture to improve the production line output rate.

The case disclosed in this case is a preferred embodiment, and any part of the modification or modification that originates from the technical idea of this case and can be easily inferred by those skilled in the art, does not deviate from the patent scope of this case.

In summary, regardless of the purpose, means and efficacy, this case is showing that it has a technical feature that is very different from the conventional ones, and its first invention is in practical use, and it is also in compliance with the patent requirements of the invention. Granted patents as soon as possible to benefit the society and feel virtuous.

10 External Flash Memory 11-17 PMOS Transistor 18-19 Capacitor 20 Organic Light Emitting Diode 30 Display Panel Driver Chip 31-32 Static Random Access Memory 33 Image Processing Unit 100 Global Screen Image 220 Global Area Image Compensation Area Needed 300 No compensation area S10 Test image output to the panel under test S11 Optical system captures the brightness distribution in the panel S12 Sub-pixel compensation modeling S13 Sub-pixel compensation model data compression S101 Performs a brightness evaluation on a global image of a display Operation to determine at least one area requiring compensation and at least one area requiring no compensation S102 A block dividing operation is performed on each of the areas requiring compensation to determine a number of picture blocks according to the brightness uniformity of the areas requiring compensation And a corresponding compensation coefficient

FIG. 1 shows a circuit diagram of a conventional internal compensation scheme. FIG. 2 illustrates a working timing diagram of one driving cycle of the conventional internal compensation scheme of FIG. 1. FIG. 3a illustrates an equivalent circuit of the conventional internal compensation scheme of FIG. 1 during the reset phase. FIG. 3b illustrates an equivalent circuit of the conventional internal compensation scheme of FIG. 1 during the compensation stage. FIG. 3c illustrates an equivalent circuit of the conventional internal compensation scheme of FIG. 1 during the light-emission phase. Figure 4 is a schematic diagram of an optical extraction compensation operation. FIG. 5 is a flow chart of an embodiment of the smart packet frame compensation method of the present invention. FIG. 6 is a schematic diagram of the grouping method of the smart grouping compensation of the present invention.

S101 Perform a brightness evaluation operation on a global screen image of a display to determine at least one area requiring compensation and at least one area not requiring compensation S102 Perform a block division operation on each of the areas requiring compensation, according to each The brightness uniformity of the area to be compensated each determines the number of picture blocks and a corresponding compensation coefficient

Claims (10)

A smart group picture compensation method, comprising: performing a brightness evaluation operation on a global picture image of a display to determine at least one area requiring compensation and at least one area requiring no compensation; and performing one for each of the areas requiring compensation A block division operation to determine a plurality of picture block groups and a plurality of compensation coefficients corresponding to the plurality of picture block groups respectively according to the brightness uniformity of each of the compensation areas; wherein each of the picture areas The block group includes at least one picture block; wherein, when performing the block division operation, the area size of each picture block is proportional to the area size of the area to be compensated and inversely proportional to the numerical size of the compensation coefficient . The smart grouping picture compensation method as described in item 1 of the patent application scope further includes storing the number of the picture blocks and the corresponding compensation coefficients of each of the areas to be compensated through a memory unit. The smart grouping picture compensation method as described in item 2 of the patent application scope, wherein the memory unit includes a random storage memory or a flash memory. The smart grouping picture compensation method as described in item 1 of the patent application scope, wherein the value of the corresponding compensation coefficient is divided into three values of slight compensation, moderate compensation, and heavy compensation. The smart group picture compensation method as described in item 1 of the patent application scope, wherein the display is a liquid crystal display, an OLED display or a Micro-LED display. A display device that uses a smart grouping picture compensation method to perform picture compensation on a display. The method includes: performing a brightness evaluation operation on a global picture image of a display to determine at least one area requiring compensation and at least one not requiring A compensation area; and performing a block division operation on each of the compensation-required areas to determine a plurality of picture block groups and corresponding to the plurality of picture block groups respectively according to the brightness uniformity of each of the compensation-required areas A plurality of compensation coefficients of the group; wherein each of the picture block groups includes at least one picture block; During the block division operation, the area size of each picture block is proportional to the area size of the area to be compensated and inversely proportional to the value of the compensation coefficient. The display device as described in item 6 of the patent application scope further includes a memory unit to store the number of the picture blocks and the corresponding compensation coefficients of each of the areas to be compensated. The display device as described in item 7 of the patent application range, wherein the memory unit includes a random storage memory or a flash memory. The display device as described in item 6 of the patent application scope, wherein the value of the corresponding compensation coefficient is divided into three values of slight compensation, moderate compensation and heavy compensation. The display device as described in item 6 of the patent application scope, wherein the display is a liquid crystal display, an OLED display or a Micro-LED display.

Images