KR20210083846A - Display device and method for controlling display device - Google Patents

Abstract

The present invention relates to a display device and a display device control method for display panel deterioration mitigation. The method includes: a step of acquiring the current value of each pixel in each unit block based on input image data; a step of acquiring the representative current value of each unit block based on the current value of each pixel in each unit block; a step of calculating the stress value of each unit block based on the representative current value and the current value of each pixel; a step of determining the compensation gain value of each pixel based on the stress value; and a step of performing compensation on the input image data based on the compensation gain value of each pixel.

Description

DISPLAY DEVICE AND METHOD FOR CONTROLLING DISPLAY DEVICE

The present specification relates to a display device and a control method of the display device, and more particularly, to a display device capable of reducing deterioration of a display panel and a control method of the display device.

Representative examples of the display device include a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), and an electroluminescence display device (Electro Luminescence). display device: ELD), electro-wetting display device (EWD), organic light emitting display device (OLED), and the like.

Among them, an organic light emitting display displays an image using an organic light emitting device that is a self-luminous device. Accordingly, the organic light emitting diode display has an advantage in that it has a smaller thickness than other display devices, a wide viewing angle, and a fast response speed. However, when the display panel deteriorates due to deterioration of pixels including the organic light emitting diode, normal image display becomes difficult, and the lifespan of the organic light emitting diode display is shortened.

The pixels included in the display panel of the organic light emitting diode display deteriorate rapidly as the current stress applied to the pixels increases. The greater the magnitude of the current applied to each pixel and the longer the current is applied to the pixel, the greater the stress applied to each pixel.

SUMMARY OF THE INVENTION An object of the present specification is to provide a display device and a control method of the display device capable of reducing deterioration of the display panel by compensating input image data through analysis of the input image and reducing current stress applied to each pixel of the display panel. will be.

Another object of the present specification is to provide a display device and a control method of the display device capable of increasing the analysis performance of an input image for reducing current stress applied to each pixel of a display panel and reducing the size of a memory required for analysis of the input image will do

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned may be understood by the following description, and will be more clearly understood by the examples of the present invention. Moreover, it will be readily apparent that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

A display device according to an exemplary embodiment of the present specification obtains a current value of each pixel included in each unit block based on input image data. In the present specification, a unit block includes one or more pixels. Meanwhile, the input image data is a value representing the gray level of each pixel, and the gray level of each pixel corresponds to the luminance of each pixel. Accordingly, in the exemplary embodiment of the present specification, a luminance value corresponding to the grayscale value of each pixel is obtained, and a current value of each pixel corresponding to the obtained luminance value is obtained.

Next, the display device according to an exemplary embodiment of the present specification obtains a representative current value of each unit block based on a current value of each pixel included in each unit block. A display device according to an embodiment of the present specification generates a histogram for a current value of each pixel included in each unit block to obtain a representative current value of each unit block, and uses the histogram to represent a representative of each unit block. Determine the current value.

Next, the display device according to the exemplary embodiment of the present specification calculates the stress value of each unit block based on the representative current value and the current value of each pixel. A display device according to an embodiment of the present specification applies a stress detection mask having a predetermined size to each unit block to detect a stress pixel and a stress block, and calculates a stress value of each unit block based on the detection result .

Next, the display device according to an exemplary embodiment of the present specification determines a compensation gain value of each pixel based on the stress value of each unit block. In an exemplary embodiment of the present specification, the display device converts the stress value of each unit block into a block gain value, and determines the block gain value of each unit block as a compensation gain value of a pixel included in each unit block. Also, according to an embodiment of the present specification, the display device may interpolate a block gain value of each unit block by applying a predetermined interpolation mask to the stress block. Also, in an exemplary embodiment of the present specification, the display device sets a pixel interpolation region on an adjacent unit block, and each pixel belonging to the pixel interpolation region based on a position of each pixel and a block gain value of each of the adjacent unit blocks The compensation gain value of the pixel may be interpolated.

Next, the display device according to an exemplary embodiment of the present specification compensates the input image data based on a compensation gain value of each pixel. Accordingly, since an image based on the compensated input image data is displayed through the display panel, deterioration of the display panel may be alleviated.

In addition, the method of controlling a display device according to an embodiment of the present specification includes: acquiring a current value of each pixel included in each unit block based on input image data; obtaining a representative current value of each unit block based on a current value; calculating a stress value of each unit block based on the representative current value and a current value of each pixel; based on the stress value determining a compensation gain value of each pixel and compensating the input image data based on the compensation gain value of each pixel.

According to the display device and the control method of the display device according to the exemplary embodiment of the present specification, deterioration of the display panel is alleviated by compensating for input image data through analysis of the input image and reducing current stress applied to each pixel of the display panel. There are advantages to doing it.

In addition, according to the display device and the control method of the display device according to the exemplary embodiment of the present specification, the analysis performance of the input image for reducing the current stress applied to each pixel of the display panel is increased, and the size of the memory required for the analysis of the input image is increased. has the advantage of reducing

1 illustrates a configuration of a display device according to an exemplary embodiment of the present specification.
2 illustrates a configuration of a timing controller according to an embodiment of the present specification.
3 shows an example of a unit block set in an embodiment of the present specification.
4 shows a histogram of a current value for each pixel generated according to an embodiment of the present specification.
5 is a diagram for explaining a method of calculating a stress value of each unit block using a stress detection mask according to an embodiment of the present specification.
6 is a diagram for explaining a method of calculating a stress value of each unit block using a stress detection mask according to another embodiment of the present specification.
7 is a graph illustrating a relationship between a stress value of each unit block and a block gain value according to an embodiment of the present specification.
8 shows an example of an interpolation mask used when interpolating a block gain value of each unit block in an embodiment of the present specification.
9 shows a block gain value set in each unit block in an embodiment of the present specification.
10 illustrates a difference value between a block gain value set in each unit block and an interpolation reference value according to an embodiment of the present specification.
11 illustrates a difference value between a block gain value of each unit block interpolated using an interpolation mask and an interpolation reference value according to an embodiment of the present specification.
12 illustrates block gain values of each unit block interpolated using an interpolation mask according to an embodiment of the present specification.
13 illustrates a pixel interpolation area set on an adjacent unit block according to an embodiment of the present specification.
14 is a diagram for explaining a method of interpolating a compensation gain value of a pixel included in a pixel interpolation region according to an embodiment of the present specification.
15 is a flowchart illustrating a method of controlling a display device according to an exemplary embodiment of the present specification.

Advantages and features of the present specification and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present specification is not limited to the embodiments disclosed below, but will be implemented in various different forms, only these embodiments allow the disclosure of the present specification to be complete, and common knowledge in the technical field to which this specification belongs It is provided to fully inform the possessor of the scope of the invention, and this specification is only defined by the scope of the claims.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present specification are illustrative and the present specification is not limited to the illustrated matters. Like reference numerals refer to like elements throughout. In addition, in the description of the present specification, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present specification, the detailed description thereof will be omitted. When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, unless otherwise explicitly stated, the case where the component is included in the singular is included.

In interpreting the components, it is interpreted as including an error range even if there is no separate explicit description.

Although the first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are only used to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the spirit of the present specification.

Each of the features of the various embodiments of the present specification may be partially or wholly combined or combined with each other, technically various interlocking and driving are possible, and each of the embodiments may be implemented independently of each other or may be implemented in conjunction with each other. may be

1 illustrates a configuration of a display device according to an exemplary embodiment of the present specification.

Referring to FIG. 1 , a display device 1 according to an exemplary embodiment of the present specification includes a display panel 10 and a panel driver 12 .

The display panel 10 emits light from the organic light emitting diode OLED of each pixel P based on the data voltage Vdata supplied from the panel driver 12 . An image corresponding to the data voltage Vdata is displayed on the display panel 10 by the light emitted from each pixel P.

The display panel 10 includes n (where n is a natural number) data lines DL and m (where m is a natural number) gate lines GL that cross each other to define a pixel area. In addition, the display panel 10 is formed in parallel with the n data lines DL and includes a plurality of driving voltage lines PL1 connected to each pixel P and a cathode voltage line PL2 connected to each pixel P. includes

Each of the n data lines DL and the m gate lines GL crosses each other with a constant interval. Each of the m gate lines GL forms m horizontal lines of the display panel 10 .

The plurality of driving voltage lines PL1 are formed to be adjacent to each of the n data lines DL in parallel to receive the driving voltage ELVDD from a power supply unit (not shown). A cathode voltage ELVSS of a low potential voltage level lower than the driving voltage ELVDD or a ground (or ground) voltage level is supplied to the cathode voltage line PL2 .

Each of the plurality of pixels P has a luminance corresponding to the data voltage Vdata supplied from the connected data line DL in response to the gate signal GS supplied from the connected gate line GL. emit light Each of the plurality of pixels P may be formed of any one of red, green, blue, and white. In an exemplary embodiment of the present specification, a unit pixel displaying one color image may include adjacent red pixels, green pixels, and blue pixels, or may include adjacent red pixels, green pixels, blue pixels, and white pixels.

Each of the plurality of pixels P includes an organic light emitting diode OLED and a pixel circuit PC.

The organic light emitting diode OLED is connected between the pixel circuit PC and the cathode voltage line PL2 and emits light in proportion to the data current supplied from the pixel circuit PC. The organic light emitting diode OLED includes an anode electrode (or pixel electrode) connected to the pixel circuit PC, a cathode electrode (or reflective electrode) connected to the cathode voltage line PL2, and an organic layer formed between the anode electrode and the cathode electrode. include Here, the organic layer may have a structure of a hole transport layer/organic emission layer/electron transport layer or a structure of a hole injection layer/hole transport layer/organic emission layer/electron transport layer/electron injection layer. In addition, a functional layer for improving luminous efficiency and/or lifespan of the organic light emitting layer may be additionally formed on the organic layer.

The pixel circuit PC is based on the data voltage Vdata supplied from the panel driver 12 to the data line DL in response to the gate signal GS supplied from the panel driver 12 to the gate line GL. A current flowing from the corresponding driving voltage line PL1 to the organic light emitting diode OLED is controlled. To this end, the pixel circuit PC controls a current flowing from the driving voltage line PL1 to the organic light emitting diode OLED based on the data voltage Vdata. A driving transistor (not shown) controls the data to the gate electrode of the driving transistor. and a switching transistor (not shown) supplying the voltage Vdata and a storage capacitor (not shown) connected between the gate electrode and the source electrode of the driving transistor to maintain the gate-source voltage of the driving transistor for one frame.

In the exemplary embodiment of the present specification, the pixel circuit PC is not limited to being composed of two transistors and one capacitor, and internal compensation for compensating a change in threshold voltage/mobility of the driving transistor inside the pixel P A compensation circuit corresponding to an external compensation structure for sensing a change in the structure or threshold voltage/mobility of the driving transistor and compensating the display panel 10 from the outside through data correction may be further included.

The panel driver 12 includes a timing controller 102 , a data driver 104 , and a gate driver 106 .

The timing controller 102 receives a timing synchronization signal TSS and input image data Idata including a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, and a main clock output from the host system 2 .

The timing controller 102 analyzes the input image data Idata and generates a compensation gain value for adjusting the amount of current flowing through each pixel. The timing controller 102 may store the generated compensation gain value in the memory 108 .

The timing controller 102 modulates the input image data Idata using the compensation gain value, and transmits the modulated input image data Mdata to the data driver 104 .

Also, the timing controller 102 generates a gate control signal GCS for controlling the gate driver 106 and a data control signal DCS for controlling the data driver 104 using the timing synchronization signal TSS, respectively. do.

The data driver 104 receives the data control signal DCS supplied from the timing controller 102 and the modulated input image data Mdata. Also, the data driver 104 receives a plurality of different reference gamma voltages from a reference gamma voltage generator (not shown). The data driver 104 samples the modulated input image data Mdata input in units of one horizontal line based on the data control signal DCS, and converts the sampled data based on a plurality of reference gamma voltages to analog data. It is converted into a voltage Vdata and supplied to the data line DL of each pixel P.

The gate driver 106 generates a gate signal GS for data addressing in response to the gate control signal GCS supplied from the timing controller 102 and sequentially supplies the generated gate signal GS to the m gate lines GL. The gate driver 106 includes a shift register that sequentially outputs the gate signal GS based on the gate control signal GCS.

2 illustrates a configuration of a timing controller according to an embodiment of the present specification.

Referring to FIG. 2 , the timing controller 102 according to an embodiment of the present specification includes a control signal generating unit 210 , a current value calculating unit 202 , a compensation gain value calculating unit 204 , and a compensating unit 206 . includes

The control signal generator 210 receives the timing synchronization signal TSS output from the host system 2 . In one embodiment of the present specification, the timing synchronization signal TSS includes a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, and a main clock.

The control signal generator 210 includes a data control signal DCS for controlling driving of the data driver 104 and a gate control signal for controlling driving of the gate driver 106 based on the timing synchronization signal TSS. GCS) is created.

The current value calculator 202 obtains a grayscale value of each pixel based on the input image data Idata. The current value calculator 202 obtains a luminance value corresponding to the grayscale value of each pixel, and obtains a current value corresponding to the luminance value.

In the embodiment of the present specification, an input image is divided into unit blocks including one or more pixels. For example, the input image may be divided into a plurality of unit blocks including 64×64 pixels, that is, 64 horizontal and 64 vertical pixels. In the embodiment of the present specification, the size of the unit block, that is, the number of pixels and the number of unit blocks included in the unit block, is determined by the resolution of the input image, the input image analysis performance of the timing controller 102 , and the input image of the timing controller 102 . It may be set differently according to the size of the memory 108 required for analysis.

The current value calculator 202 generates a histogram of the current value of each pixel included in each unit block. The current value calculator 202 determines, as a representative current value of a unit block, a current value corresponding to a frequency matching a predetermined reference ratio value among all frequencies of the generated histogram.

The compensation gain value calculator 204 calculates a stress value of each unit block based on a representative current value of each unit block and a current value of each pixel included in each unit block.

In one embodiment of the present specification, the compensation gain value calculator 204 applies a stress detection mask having a predetermined size to each pixel constituting the unit block in order to calculate the stress value of each unit block. The compensation gain value calculating unit 204 compares the current value of each pixel included in the stress detection mask with the representative current value of the unit block, and the current value of each pixel included in the stress detection mask and each pixel belongs to. A stress pixel is detected by comparing the representative current values of the unit blocks. Then, the compensation gain value calculating unit 204 sets the frequency corresponding to the predetermined reference ratio value among the total frequencies of the histogram for the representative current value of the unit block, the number of stress pixels, and the current value of each pixel included in the stress block. The stress value of the unit block is calculated based on the current value corresponding to .

In one embodiment of the present specification, if the number of stress pixels included in the unit block is greater than a predetermined reference value, the unit block is designated as a stress block.

The compensation gain value calculator 204 converts the stress value of each unit block into a block gain value, and determines the block gain value of each unit block as a compensation gain value of a pixel belonging to each unit block. The compensation gain value calculator 204 may convert the stress value of each unit block into a block gain value by referring to the stress value and the table in which the block gain value corresponding to the stress value is recorded.

In an embodiment of the present specification, the compensation gain value calculator 204 interpolates the block gain values of each unit block by applying a predetermined interpolation mask to the stress block.

In addition, in an embodiment of the present specification, the compensation gain value calculating unit 204 sets a pixel interpolation area on an adjacent unit block, and based on the position of each pixel and the block gain value of each adjacent unit block, the pixel The compensation gain value of each pixel belonging to the interpolation region is interpolated.

Hereinafter, a process of mitigating deterioration of the display panel 10 by analyzing an input image by the display device 1 according to an exemplary embodiment of the present specification will be exemplarily described with reference to FIGS. 1 to 14 .

In an embodiment of the present specification, a unit block may be set in the input image or the display panel 10 in order to analyze the input image.

3 shows an example of a unit block set in an embodiment of the present specification. In an embodiment of the present specification, as shown in FIG. 3 , the display panel 10 or an image 30 to be displayed on the display panel 10 . ), a plurality of unit blocks 302 are set. The unit block 302 includes one or more pixels. In the embodiment of FIG. 3 , one unit block 302 includes 64×64 pixels, that is, 64 pixels horizontally and 64 pixels vertically. However, the size of the unit block, that is, the number of pixels and the number of unit blocks included in the unit block, depends on the resolution of the input image, the input image analysis performance of the timing controller 102 , and the memory required for the input image analysis of the timing controller 102 . It can be set differently according to the size of (108).

When the input image data Idata is input, the current value calculator 202 obtains a current value of each pixel included in each unit block based on the input image data Idata.

More specifically, the current value calculator 202 first obtains a grayscale value of each pixel corresponding to the input image data. Then, the current value calculator 202 obtains a luminance value of each pixel corresponding to the grayscale value of each pixel. In an embodiment of the present specification, the current value calculator 202 may obtain a luminance value of each pixel by referring to a grayscale value and a table in which a luminance value corresponding to the grayscale value is recorded.

Subsequently, the current value calculator 202 obtains a current value of each pixel corresponding to the luminance value of each pixel. In an embodiment of the present specification, the current value calculator 202 may obtain a current value of each pixel by referring to a table in which a luminance value and a current value corresponding to the luminance value are recorded.

When the current value of each pixel included in each unit block set in the input image is obtained, the current value calculator 202 determines the representative current of each unit block based on the current value of each pixel included in each unit block. get the value

In order to obtain the representative current value of each unit block, the current value calculator 202 first generates a histogram of the current value of each pixel for each unit block. 4 shows a histogram of a current value for each pixel generated according to an embodiment of the present specification. As shown in FIG. 4 , the current value calculator 202 generates a histogram having the number of pixels having each current value as a frequency. A histogram as shown in FIG. 4 is generated for each unit block.

Next, the current value calculator 202 determines, as a representative current value of the corresponding unit block, a current value corresponding to a frequency matching a predetermined reference ratio value among all frequencies of the generated histogram. For example, when the reference ratio value is set to 5%, the current value calculating unit 202 searches for the frequency corresponding to the top 5% among the total frequencies of the histogram of the unit block, and sets the current value corresponding to the search frequency to the unit block is determined by the representative current value of Here, the reference ratio value used by the current value calculator 202 may be set differently depending on the embodiment. Accordingly, a representative current value of each unit block is determined.

When the representative current value of each unit block is determined, the compensation gain value calculator 204 sets the stress value of each unit block based on the representative current value of each unit block and the current value of each pixel included in each unit block. to calculate

In an embodiment of the present specification, the compensation gain value calculator 204 may calculate the stress value of each unit block using a stress detection mask having a predetermined size.

5 is a diagram for explaining a method of calculating a stress value of each unit block using a stress detection mask according to an embodiment of the present specification.

In the embodiment of FIG. 5 , the compensation gain value calculator 204 calculates the stress value of the unit block 502 using the stress detection mask 50 having 3×3, that is, 3 horizontal and 3 vertical pixels. assume that Also, in the embodiment of FIG. 5 , it is assumed that the unit block 502 has 4×4 pixels, that is, 4 horizontally and 4 vertically. Also, in the embodiment of FIG. 5 , it is assumed that the representative current value of the unit block 502 is 100, and the reference ratio value used in generating the histogram is 25%. Also, a numerical value written to each pixel of the unit block 502 shown in FIG. 5 means a current value of each pixel. However, the size of the stress detection mask and the size of the unit block 502 may vary according to embodiments.

The compensation gain value calculator 204 applies the stress detection mask 50 to each pixel of the unit block 502 . Here, applying the stress detection mask 50 to each pixel means matching the center pixel 52 of the stress detection mask with each pixel of the unit block 502 . Accordingly, the compensation gain value calculator 204 applies the stress detection mask 50 as much as the total number of pixels (eg, 16) of the unit block 502 .

When the stress detection mask 50 is applied to each pixel of the unit block 502 , the compensation gain value calculator 204 determines the current value of each pixel included in the stress detection mask 50 and the value of the unit block 502 . A stressed pixel is detected by comparing the representative current values. In this specification, a pixel having a current value greater than or equal to the representative current value of the unit block 502 among pixels included in the stress detection mask 50 is defined as a 'stress pixel'. For example, when the current value of any pixel of the unit block 502 is 100 and the representative current value of the unit block 502 is 100, the pixel is determined as a stress pixel.

The compensation gain value calculator 204 checks the number of stress pixels checked when the stress detection mask 50 is applied to each pixel of the unit block 502, and determines the number of the checked stress pixels in the first first If it is greater than the reference value, the count value is incremented by 1. For example, when the first reference value is set to 2 and the stress detection mask 50 is applied to (1, 1) pixels, that is, the first horizontal and first vertical pixels, as shown in FIG. 5, the stress detection mask 50 One pixel ((2, 2) pixel) has a current value of 100 or more, which is a representative current value of the unit block 502, among pixels included in . Therefore, in this case, the count value does not increase.

The compensation gain value calculator 204 applies the stress detection mask 50 to all pixels of the unit block 502 shown in FIG. 5 in the above-described manner, and when the stress detection mask 50 is applied, The count value is incremented or not incremented according to the result of comparing the count with the first reference value.

When the application of the stress detection mask 50 is completed for all pixels, the compensation gain value calculating unit 204 compares the count value with a second predetermined reference value. If the count value is greater than the second reference value, the compensation gain value calculator 204 determines the corresponding unit block as the stress block.

In the embodiment of FIG. 5 , the count value becomes 1 after the stress detection mask 50 is applied to all pixels of the unit block 502 . (The count value is increased because there are 3 stress pixels only when the stress detection mask 50 is applied to the (3, 2) pixel) If the second reference value is set to 3, the count value of the unit block 502 is Since it is less than 3, the unit block 502 is not designated as a stress block.

In addition, the compensation gain value calculating unit 204 selects among the total frequency of the histogram for the representative current value of the unit block 502 , the count value of the unit block 502 , and the current value of each pixel included in the unit block 502 . The stress value of the unit block 502 is calculated based on the frequency coincident with the predetermined reference ratio value. More specifically, the stress value of the unit block 502 is {(representative current value of unit block × count value of unit block)/(a predetermined criterion among the total frequencies of the histogram for the current value of each pixel included in the unit block) frequency corresponding to the ratio value)}.

For example, in the embodiment of FIG. 5 , the representative current value of the unit block 502 is 100, the count value of the unit block 502 is 1, and the total histogram of the current values of each pixel included in the unit block 502 is When the frequency matching the predetermined reference ratio value (eg, 25%) among the frequencies is 4, the stress value of the unit block 502 is determined to be 100×1/4=25.

As a result, in the embodiment of FIG. 5 , the stress value of the unit block 502 is 25 and the unit block 502 is not designated as a stress block.

6 is a diagram for explaining a method of calculating a stress value of each unit block using a stress detection mask according to another embodiment of the present specification.

In the embodiment of FIG. 6 , the compensation gain value calculating unit 204 calculates the stress value of the unit block 504 by using the stress detection mask 50 having 3×3, that is, 3 horizontal and 3 vertical pixels. assume that Also, in the embodiment of FIG. 6 , it is assumed that the unit block 504 has 4×4 pixels, that is, 4 horizontally and 4 vertically. Also, in the embodiment of FIG. 6 , it is assumed that the representative current value of the unit block 504 is 100, and the reference ratio value used in generating the histogram is 25%. Also, a numerical value written to each pixel of the unit block 502 shown in FIG. 6 means a current value of each pixel.

The compensation gain value calculator 204 applies the stress detection mask 50 to all pixels in the same manner as in the embodiment of FIG. 5 . As a result, the count value of the unit block 504 is 4, and when the second reference value is 3, the unit block 504 is designated as a stress block. In addition, when the frequency matching the predetermined reference ratio value (eg, 25%) among the total frequencies of the histogram for the current value of each pixel included in the unit block 504 is 4, the stress value of the unit block 504 is It is determined as 100×4/4=100.

Based on the method described with reference to FIGS. 4 and 5 , the compensation gain value calculator 204 calculates the stress values of all unit blocks constituting the input image, thereby generating a stress map ( map) can be created.

When the stress map generation is completed, the compensation gain value calculator 204 converts the stress value of each unit block into a block gain value. 7 is a graph illustrating a relationship between a stress value of each unit block and a block gain value according to an embodiment of the present specification. The compensation gain value calculator 204 may convert the stress value of each unit block into a block gain value by referring to a table in which the stress value and the corresponding block gain value are recorded as shown in FIG. 7 .

In FIG. 7 , SL denotes a minimum reference value and SH denotes a maximum reference value. In the embodiment of FIG. 7 , the compensation gain value calculating unit 204 sets the block gain value to 1 when the stress value of the unit block is less than or equal to the minimum reference value SL, and the stress value of the unit block is the maximum reference value SH ) or higher, set the block gain value to 0.5. In addition, if the stress value of the unit block is greater than the minimum reference value SL and less than the maximum reference value SH, the compensation gain value calculating unit 204 determines that as the stress value increases, the block gain value becomes smaller as shown in FIG. 7 . Set the block gain value so that The block gain values (1, 0.5) and the slope of the graph displayed in the graph shown in FIG. 7 may be set differently depending on the embodiment.

The compensation gain value calculator 204 may determine the block gain value of each unit block as the compensation gain value of each pixel included in each unit block.

However, in an embodiment of the present specification, the compensation gain value calculator 204 uses a predetermined interpolation mask before determining the block gain value of each unit block as the compensation gain value of each pixel included in each unit block. Thus, the block gain value of each unit block can be interpolated. (See FIGS. 8 to 12)

8 shows an example of an interpolation mask used when interpolating a block gain value of each unit block in an embodiment of the present specification.

In the embodiment of Fig. 8, the interpolation mask 80 has 3x3, that is, 3 horizontal and 3 vertical pixels, and each pixel is assigned an interpolation index for interpolation. However, the size of the interpolation mask and the interpolation index allocated to each pixel of the interpolation mask may be set differently according to embodiments.

9 shows a block gain value set in each unit block in an embodiment of the present specification, and FIG. 10 shows a difference value between a block gain value set in each unit block and an interpolation reference value in an embodiment of the present specification. Also, FIG. 11 shows a difference value between a block gain value of each unit block interpolated using an interpolation mask and an interpolation reference value in an embodiment of the present specification, and FIG. 12 is an interpolation mask using an interpolation mask in an embodiment of the present specification. It represents the block gain value of each interpolated unit block.

In the embodiment of FIG. 9 , the input image 82 is composed of 5×5 unit blocks, and a number recorded in each unit block indicates a block gain value of each unit block. 9, the unit block 802 and the unit block 804 have block gain values of 0.8 and 0.7, respectively, and are stress blocks.

The compensation gain value calculating unit 204 calculates a difference value between a predetermined interpolation reference value (eg, 1) and a block gain value of each unit block shown in FIG. 9 . As shown in FIG. 10 , the difference value between the interpolation reference value (eg, 1) and the block gain value of the unit block 802 is 0.2, and the interpolation reference value (eg, 1) and the block gain of the unit block 804 . The difference between the values is 0.3. Also, a difference value between the interpolation reference value (eg, 1) and the remaining unit blocks becomes 0.

The compensation gain value calculator 204 applies the interpolation mask 80 shown in FIG. 8 to the unit blocks 802 and 804 that are stress blocks among the unit blocks shown in FIG. 10 , respectively. Accordingly, the difference value between the unit block 802 and the unit block included in the interpolation mask 80 among neighboring blocks centered on the unit block 804 is changed according to the interpolation index of the interpolation mask 80 . For example, the difference value between the upper, lower, and left unit blocks of the unit block 802 is changed to a value corresponding to 1/2 of the difference value of the unit block 802 according to the interpolation index of the interpolation mask 80 . do. At this time, the difference value of the stress block among the unit blocks included in the interpolation mask 80 is not changed.

When the interpolation mask application is completed, the compensation gain value calculator 204 determines the block gain value of each unit block by subtracting the difference value of each unit block from the interpolation reference value (eg, 1). Accordingly, as shown in FIG. 12 , the block gain values of the neighboring unit blocks are interpolated around the block gain values of the unit block 802 and the unit block 804 that are the stress blocks.

After the block gain value is interpolated by the above-described process, the compensation gain value calculator 204 may determine the block gain value of each unit block as the compensation gain value of each pixel included in each unit block.

The compensation gain value calculation unit 204 may transmit the compensation gain value of each pixel determined by the above-described process to the compensation unit 206 . However, in the exemplary embodiment of the present specification, before transmitting the compensation gain value of each pixel to the compensation unit 206 , the compensation gain value calculating unit 204 interpolates the compensation gain values of pixels belonging to the boundary of each unit block. can do. (See FIGS. 13 and 14)

13 illustrates a pixel interpolation area set on an adjacent unit block according to an embodiment of the present specification. 14 is a diagram for explaining a method of interpolating a compensation gain value of a pixel included in a pixel interpolation region according to an embodiment of the present specification.

In the embodiment of FIG. 13 , the input image 84 is composed of 2×2, that is, four adjacent unit blocks 842 , 844 , 846 , 848 , and each unit block 842 , 844 , 846 , 848 . is composed of 64×64 pixels. In addition, BG1, BG2, BG3, and BG4 mean block gain values of each of the unit blocks 842, 844, 846, and 848.

As shown in FIG. 13 , the compensation gain value calculator 204 sets the pixel interpolation region 85 connecting the centers of each of the unit blocks 842 , 844 , 846 , and 848 . However, the size and setting method of the pixel interpolation region may vary according to embodiments.

Subsequently, the compensation gain value calculator 204 interpolates the compensation gain value of each pixel included in the pixel interpolation area 85 shown in FIG. 14 .

As shown in FIG. 14 , when the compensation gain value of the pixel 850 included in the pixel interpolation area 85 is interpolated, the compensation gain value calculating unit 204 sets the position of the pixel 850 as the center. The areas of the individual regions 862 , 864 , 866 , and 868 are calculated, respectively, and the ratio of the total area of the pixel interpolation region 85 to the area of each of the regions 862 , 864 , 866 and 868 is calculated. Then, the compensation gain value calculating unit 204 calculates the ratio of the total area of the pixel interpolation area 85 and the area of each area 862 , 864 , 866 and 868 to each unit block 842 , 844 , 846 , and 848 . A value obtained by summing values obtained by multiplying the block gain values BG1, BG2, BG3, and BG4 of the pixel 850 is determined as the pixel gain value of the pixel 850 .

For example, in FIG. 14 , the total area of the pixel interpolation region 85 is P, the area of the region 862 is a, the area of the region 864 is b, the area of the region 866 is c, and the area of the region 868 is Assuming that the area is d, the pixel gain value of the pixel 850 is (a/P)×BG1+(b/P)×BG2+(c/P)×BG3+(d/P)×BG4.

The compensation gain value calculating unit 204 calculates pixel gain values of all pixels included in the pixel interpolation region 85 through the above-described process. Accordingly, pixel gain values of all pixels included in the pixel interpolation region 85 are interpolated.

When the pixel gain value of each pixel of the input image is determined by the above-described process, the compensation gain value calculating unit 204 transmits the pixel gain value of each pixel to the compensating unit 206 .

The compensator 206 applies the pixel gain value of each pixel to the input image data Idata. Accordingly, input image data of each pixel is compensated and modulated by a pixel gain value, and modulated input image data Mdata is generated. The modulated input image data Mdata is transmitted to the data driver 104 , and an image based on the modulated input image data Mdata is displayed on the display panel 10 .

As a result, when an image is displayed on the display panel 10 by the above-described process, the magnitude of the current flowing through the pixel in the area corresponding to the stress block is reduced. Accordingly, the degradation rate of each pixel of the display panel 10 can be delayed, so that degradation of the display panel 10 is alleviated.

15 is a flowchart illustrating a method of controlling a display device according to an exemplary embodiment of the present specification.

As shown in FIG. 15 , when input image data is input to the timing controller 102 of the display device 1 according to an exemplary embodiment of the present specification, the current value calculator 202 is configured to calculate each of the input image data based on the input image data. A current value of each pixel included in the unit block of is obtained ( 902 ).

In an exemplary embodiment of the present specification, the step of obtaining ( 902 ) the current value of each pixel included in each unit block set in the display panel based on the input image data includes the luminance value corresponding to the grayscale value of each pixel. acquiring and acquiring a current value corresponding to the luminance value.

Next, the current value calculator 202 obtains a representative current value of each unit block based on the current value of each pixel included in each unit block ( S904 ).

In one embodiment of the present specification, the step 904 of obtaining a representative current value of each unit block based on the current value of each pixel included in each unit block includes the current of each pixel included in each unit block. generating a histogram of values; and determining, as a representative current value of a unit block, a current value corresponding to a frequency matching a predetermined reference ratio value among all frequencies of the generated histogram.

Next, the compensation gain value calculator 204 calculates a stress value of each unit block based on the representative current value and the current value of each pixel ( S906 ).

In an embodiment of the present specification, the step of calculating the stress value of each unit block based on the representative current value and the current value of each pixel includes a stress detection mask having a predetermined size for each pixel constituting the unit block. , detecting a stressed pixel by comparing the current value of each pixel included in the stress detection mask with a representative current value of a unit block to which each pixel belongs, and calculating a count value based on the number of stressed pixels and calculating the stress value of the unit block based on the frequency matching the predetermined reference ratio value among the total frequencies of the histogram for the representative current value, count value, and current value of each pixel included in the unit block. include

In addition, in one embodiment of the present specification, the calculating of the count value based on the number of stress pixels includes a first reference value in which the number of stress pixels is predetermined when the stress detection mask is applied to each pixel included in the unit block. and increasing the count value if greater than the second reference value, and determining the unit block as a stress block if the count value is greater than a predetermined second reference value.

Next, the compensation gain value calculator 204 determines a compensation gain value of each pixel based on the stress value of each unit block ( S908 ).

In one embodiment of the present specification, the step of determining the compensation gain value of each pixel based on the stress value ( 908 ) includes converting the stress value of each unit block into a block gain value and the block gain of each unit block and determining the value as a compensation gain value of a pixel belonging to each unit block.

Also, in one embodiment of the present specification, the step of determining the compensation gain value of each pixel based on the stress value ( 908 ) is the step of interpolating the block gain value of each unit block by applying a predetermined interpolation mask to the stress block. further includes

In addition, in an embodiment of the present specification, the step of determining the compensation gain value of each pixel based on the stress value ( 908 ) includes setting a pixel interpolation area on an adjacent unit block and the position of each pixel and the adjacent unit. The method further includes interpolating a compensation gain value of each pixel belonging to the pixel interpolation region based on the block gain value of each block.

Next, the compensator 206 compensates the input image data based on the compensation gain value of each pixel ( S910 ).

In general, as the size of each unit block set in the image analysis process, that is, the number of pixels included in each unit block increases, the size of the memory 108 required for image analysis decreases, but image analysis performance decreases.

Meanwhile, according to an embodiment of the present specification, a histogram based on the current value of each unit block is used in the image analysis process, and the representative current value of each unit block is calculated regardless of the number of pixels included in each unit block. The image analysis performance can be adjusted by adjusting only the reference ratio value used for determining. That is, the higher the reference ratio value, the higher the image analysis performance. As a result, according to an embodiment of the present specification, image analysis performance can be improved only by increasing the reference ratio value while maintaining a relatively small size of the memory 108 required for image analysis.

Embodiments of the present specification have been described in more detail with reference to the accompanying drawings as described above. However, the present specification is not necessarily limited to these embodiments, and various modifications may be made without departing from the spirit of the present specification. Accordingly, the embodiments disclosed in the present specification are for explanation rather than limiting the technical spirit of the present specification, and the scope of the technical spirit of the present specification is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present specification should be construed by the claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present specification.

Claims (16)

obtaining a current value of each pixel included in each unit block based on the input image data;
obtaining a representative current value of each unit block based on a current value of each pixel included in each unit block;
calculating a stress value of each unit block based on the representative current value and the current value of each pixel;
determining a compensation gain value of each pixel based on the stress value; and
Compensating the input image data based on the compensation gain value of each pixel
How to control the display device.
According to claim 1,
The step of obtaining a current value of each pixel included in each unit block set in the display panel based on the input image data includes:
obtaining a luminance value corresponding to the grayscale value of each pixel; and
acquiring a current value corresponding to the luminance value
How to control the display device.
According to claim 1,
The step of obtaining a representative current value of each unit block based on the current value of each pixel included in each unit block includes:
generating a histogram of a current value of each pixel included in each of the unit blocks; and
determining, as a representative current value of the unit block, a current value corresponding to a frequency matching a predetermined reference ratio value among all frequencies of the histogram
How to control the display device.
According to claim 1,
Calculating the stress value of each unit block based on the representative current value and the current value of each pixel includes:
applying a stress detection mask having a predetermined size to each pixel constituting the unit block;
detecting a stress pixel by comparing a current value of each pixel included in the stress detection mask with a representative current value of a unit block to which each pixel belongs, and calculating a count value based on the number of the stress pixels; and
Calculating the stress value of the unit block based on the frequency matching the predetermined reference ratio value among the total frequencies of the histogram for the representative current value of the unit block, the count value, and the current value of each pixel included in the unit block comprising the steps of
How to control the display device.
5. The method of claim 4,
Calculating a count value based on the number of stress pixels includes:
increasing the count value when the number of stress pixels is greater than a predetermined first reference value when the stress detection mask is applied to each pixel included in the unit block; and
and determining the unit block as the stress block when the count value is greater than a second predetermined reference value.
How to control the display device.
According to claim 1,
The step of determining a compensation gain value of each pixel based on the stress value includes:
converting the stress value of each unit block into a block gain value; and
determining a block gain value of each unit block as a compensation gain value of a pixel belonging to each unit block;
How to control the display device.
7. The method of claim 6,
The step of determining a compensation gain value of each pixel based on the stress value includes:
The method further comprising the step of interpolating the block gain value of each unit block by applying a predetermined interpolation mask to the stress block
How to control the display device.
7. The method of claim 6,
The step of determining a compensation gain value of each pixel based on the stress value includes:
setting a pixel interpolation area on an adjacent unit block; and
The method further comprising the step of interpolating a compensation gain value of each pixel belonging to the pixel interpolation region based on the position of each pixel and the block gain value of each of the adjacent unit blocks
How to control the display device.
a display panel including a plurality of pixels;
a data driver for driving a data line of the display panel;
a gate driver driving a gate line of the display panel;
a timing controller for controlling driving of the data driver and the gate driver;
the timing controller
obtaining a current value of each pixel included in each unit block based on input image data, and obtaining a representative current value of each unit block based on a current value of each pixel included in each unit block current value calculator;
a compensation gain value calculator for calculating a stress value of each unit block based on the representative current value and a current value of each pixel, and determining a compensation gain value for each pixel based on the stress value; and
and a compensator compensating the input image data based on the compensation gain value of each pixel.
display device.
10. The method of claim 9,
The current value calculation unit
obtaining a luminance value corresponding to the grayscale value of each pixel, and obtaining a current value corresponding to the luminance value
display device.
10. The method of claim 9,
The current value calculation unit
A histogram of the current value of each pixel included in each unit block is generated, and a current value corresponding to a frequency matching a predetermined reference ratio value among all frequencies of the histogram is determined as the representative current value of the unit block doing
display device.
According to claim 1,
The compensation gain value calculation unit
A stress detection mask having a predetermined size is applied to each pixel constituting the unit block, and a current value of each pixel included in the stress detection mask is compared with a representative current value of a unit block to which each pixel belongs. to detect the stressed pixels and calculate a count value based on the number of the stressed pixels, among the total frequency of the histogram for the representative current value of the unit block, the count value, and the current value of each pixel included in the unit block calculating a stress value of the unit block based on a frequency that matches a predetermined reference ratio value
display device.
13. The method of claim 12,
The compensation gain value calculation unit
When the stress detection mask is applied to each pixel included in the unit block, if the number of stressed pixels is greater than a first predetermined reference value, the count value is increased, and the count value is greater than a predetermined second reference value. If it is large, the unit block is determined as the stress block.
display device.
10. The method of claim 9,
The compensation gain value calculation unit
converting the stress value of each unit block into a block gain value, and determining the block gain value of each unit block as a compensation gain value of a pixel belonging to each unit block
display device.
15. The method of claim 14,
The compensation gain value calculation unit
The block gain value of each unit block is interpolated by applying a predetermined interpolation mask to the stress block.
display device.
15. The method of claim 14,
The compensation gain value calculation unit
setting a pixel interpolation area on an adjacent unit block; and
interpolating a compensation gain value of each pixel belonging to the pixel interpolation region based on the position of each pixel and the block gain value of each of the adjacent unit blocks
display device.

Images