KR20240028747A - Display device and method for controlling brightness using quaternary-tree thereof - Google Patents

Abstract

A method of controlling luminance of a display device according to one aspect includes obtaining luminance data corresponding to luminance of each pixel for a plurality of pixels; calculating a luminance difference for each pixel representing a difference between the luminance for each pixel and a reference luminance from the luminance data; generating correction data based on the luminance difference for each pixel; and storing the correction data using a quad-tree.

Description

Display device and brightness control method using its quaternary-tree {DISPLAY DEVICE AND METHOD FOR CONTROLLING BRIGHTNESS USING QUATERNARY-TREE THEREOF}

It relates to a display device and a luminance control method using its quad-tree.

As information technology develops, the importance of display devices, which are a connecting medium between users and information, is emerging. In response to this, the use of display devices such as liquid crystal display devices and organic light emitting display devices is increasing.

These display devices may include a display panel including pixels that emit light, a data driver that supplies a data signal to the display panel, and a scan driver that supplies a scan signal to the display panel.

Each of the pixels receives a data signal from the data driver in response to the scanning signal, and emits light with a brightness corresponding to the data signal. However, luminance differences may occur between pixels due to the characteristics of each pixel and differences in the manufacturing process. Therefore, in order to provide a display device with uniform image quality, a method of controlling the luminance by measuring the luminance of each pixel is being developed.

Domestic Patent Publication No. 10-2016-0016020 (2016.02.15)

The aim is to provide a luminance control method using a display device and its quad-tree. Additionally, the object is to provide a computer-readable recording medium on which a program for executing the method on a computer is recorded. The technical challenges to be solved are not limited to those described above, and other technical challenges may exist.

A method of controlling luminance of a display device according to one aspect includes obtaining luminance data corresponding to luminance of each pixel for a plurality of pixels; calculating a luminance difference for each pixel representing a difference between the luminance for each pixel and a reference luminance from the luminance data; generating correction data based on the luminance difference for each pixel; and storing the correction data using a quad-tree.

A display device according to another aspect includes a display panel including a plurality of pixels forming at least one row and one column; a control unit configured to apply input image data and corrected image data to the display panel to obtain first output image data, and obtain luminance data corresponding to luminance for each pixel based on the first output image data; and a compensation unit that calculates a pixel-specific luminance difference between the pixel-specific luminance and the reference luminance from the luminance data, generates correction data based on the pixel-specific luminance difference, and stores the correction data using a quaternary tree. Includes ;

According to the present invention, it is possible to minimize the increase in cost due to the addition of a compensation circuit by reducing the amount of data for luminance correction and integrating a low-capacity memory into the driving chip.

In addition, when controlling the brightness of a display device, it is possible to adjust the strength or weakness of correction for each area of the display panel, thereby providing a more accurate and delicate method of controlling the brightness of the display device.

Additionally, the multi-screen display device according to an embodiment of the present invention can provide a display device without yield loss by performing luminance correction for each of a plurality of display modules and luminance correction between display modules.

The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

FIG. 1 is a block diagram illustrating an example of a display device according to an embodiment.
Figure 2 is a block diagram showing an example of the configuration of a compensation unit according to an embodiment.
FIG. 3 is a flowchart illustrating an example of a method for controlling luminance of a display device according to an embodiment.
Figure 4 is a flowchart illustrating an example of generating compression correction data according to an embodiment.
FIG. 5 is a diagram illustrating an example of generating compression correction data using a quaternary tree in one embodiment.
FIG. 6 is a diagram illustrating an example of a quaternary tree used when generating compression correction data according to an embodiment.
FIG. 7 is a diagram for explaining an example of the size of a quaternary tree according to an embodiment.
FIG. 8 is a flowchart illustrating an example of storing first correction data using the median value of the luminance difference for each pixel, according to an embodiment.
Figure 9 is a flowchart for explaining an example of generating compression correction data according to an embodiment.
FIG. 10 is a flowchart illustrating an example of decoding using a linear interpolation method according to an embodiment.
FIG. 11 is a diagram illustrating an example of the luminance of four pixels and the difference in luminance of each pixel according to an embodiment.
FIG. 12 is a diagram illustrating an example of generating compression correction data using an intermediate value according to an embodiment.
FIG. 13 is a diagram illustrating an example of decoding using a linear interpolation method according to an embodiment.
Figure 14 is a block diagram showing another example of a display device according to an embodiment.
Figure 15 is a luminance distribution diagram for test images of a plurality of display modules according to an embodiment.

The terms used in the embodiments are general terms that are currently widely used as much as possible, but may vary depending on the intention or precedent of a technician working in the art, the emergence of new technology, etc. In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the relevant description. Therefore, terms used in the specification should be defined based on the meaning of the term and the overall content of the specification, not just the name of the term.

When it is said that a part "includes" a certain element throughout the specification, this means that, unless specifically stated to the contrary, it does not exclude other elements but may further include other elements. Additionally, terms such as “unit” and “module” used in the specification refer to a unit that processes at least one function or operation, which may be implemented as hardware or software, or as a combination of hardware and software. Additionally, a “part” may be a hardware component, such as a processor or circuit, and/or a software component executed by the hardware component, such as a processor.

Additionally, terms including ordinal numbers such as “first” or “second” used in the specification may be used to describe various components, but the components should not be limited by the terms. The above terms may be used for the purpose of distinguishing one component from another component.

Below, the embodiment will be described in detail with reference to the attached drawings. However, the embodiments may be implemented in various different forms and are not limited to the examples described herein.

FIG. 1 is a block diagram illustrating an example of a display device according to an embodiment.

Referring to FIG. 1 , a display device 10 according to an embodiment may include a display panel 110 and a driver 120A.

The display panel 110 may include a plurality of pixels (PX) arranged in various patterns such as a predetermined pattern, for example, a matrix type or a zigzag pattern. A pixel (PX) emits one color, for example, one of red, blue, green, and white. Pixels (PX) may emit colors other than red, blue, green, and white.

The pixel (PX) may include a light emitting device. The light emitting device may be a self-emitting device. For example, the light emitting device may be a light emitting diode (LED). The light-emitting device may be a light-emitting diode (LED) with a size ranging from micro to nanoscale. A light emitting diode may emit light at a single peak wavelength or may emit light at multiple peak wavelengths. The light emitting diode may be made of an LED chip, may have a phosphor layer on the LED chip, or may optionally use a light emitting diode package in which the LED chip is packaged. The phosphor layer can emit light at one or more peak wavelengths emitted from the LED chip.

The pixel PX may further include a pixel circuit connected to the light emitting device. The pixel circuit may include at least one thin film transistor and at least one capacitor. The pixel circuit can be implemented by a semiconductor stacked structure within an LED chip.

The driver 120A may include a scan driver 122, a source driver 124, a compensation unit 126, and a control unit 128. The driver 120A may be implemented as a System On Chip (SOC) processor and electrically connected to the display panel 110. System On Chip Processor refers to an IC that contains a microprocessor, built-in memory, multiple peripheral devices, and an external bus interface in one chip.

The scan driver 122 is connected to a plurality of scan lines connected to the pixels PX of the display panel 110, and can apply scan signals to the scan lines.

The source driver 124 is connected to a plurality of data lines connected to the pixels (PX) of the display panel 110, and converts the luminance-corrected image data (DATA') received from the control unit 128 into a signal in the form of voltage or current. It can be converted to and applied to data lines.

The compensation unit 126 may provide data (CD) for luminance correction of the input image data (DATA) (raw data) to the control unit 128. As an example, data (CD) for luminance correction may be correction data. As another example, data (CD) for luminance correction may be second correction data.

The compensator 126 may previously generate and store data (CD) for luminance correction. As an example, the compensator 126 may calculate a luminance difference for each pixel, which represents the difference between the luminance for each pixel and the reference luminance, from the luminance data, and generate correction data based on the luminance difference for each pixel using a four-tree. there is. Here, the luminance data may be data corresponding to the luminance of each pixel based on output image data (hereinafter referred to as 'first output image data') obtained by applying input image data to a display device including a plurality of pixels. there is. The compensation unit 126 may obtain luminance data from the control unit 128. Correction data may be data corresponding to the difference in luminance for each pixel. The compensation unit 126 can save memory capacity in the display device by storing compression correction data that compresses the correction data using a quaternary tree. In addition, the compensation unit 126 may obtain correction data by decoding the compression correction data and provide the correction data to the control unit 128. As another example, the compensator 126 generates a pixel-specific luminance difference indicating the difference between the pixel-specific luminance and the reference luminance from the luminance data corresponding to the pixel-specific luminance of four or more pixels among the plurality of pixels included in the display panel. The memory capacity in the display device can be reduced by calculating, generating first correction data based on the luminance difference for each pixel, and storing compression correction data that compresses the first correction data using the median value of the luminance difference for each pixel. You can. In addition, the compensation unit 126 may obtain second correction data by decoding the compression correction data using linear interpolation and provide the second correction data to the control unit 128.

The control unit 128 may generate a scan control signal and a data control signal and transmit them to the scan driver 410 and the source driver 430, respectively. The control unit 128 receives input image data (DATA) from an external source (e.g., a graphics controller), and corrects the luminance of the input image data (DATA) using data (CD) for luminance correction. (DATA') can be transmitted to the source driver 124. The control unit 128 may convert input image data (DATA) into corrected image data (DATA') using data (CD) for luminance correction. Additionally, the control unit 128 may obtain second output image data by applying the corrected image data to a display device including a plurality of pixels. As an example, the control unit 128 may generate corrected image data by converting input image data using correction data. As another example, the control unit 128 may generate corrected image data by converting input image data using second correction data.

Although not shown, the driving unit 120A receives external power and/or internal power and converts it into voltages of various levels required for the operation of each component, and converts the corresponding voltages to the display panel 110 under the control of the control unit 50. ) may further include a power supply unit that supplies power.

Figure 2 is a block diagram showing an example of the configuration of a compensation unit according to an embodiment.

Referring to FIG. 2 together, the compensation unit 126 may include an encoder 1261, a memory 1267, and a decoder 1269.

The encoder 1261 may include a correction data generation unit 1263 and a compression unit 1265.

As an example, the correction data generator 1263 obtains luminance data corresponding to the luminance of each pixel for a plurality of pixels, calculates a luminance difference for each pixel indicating the difference between the luminance of each pixel and the reference luminance from the luminance data, , Correction data can be generated based on the luminance difference for each pixel. As another example, the correction data generator 1263 obtains luminance data corresponding to the luminance of each pixel for four or more pixels among a plurality of pixels, and generates a pixel representing the difference between the luminance of each pixel and the reference luminance from the luminance data. The luminance difference for each pixel may be calculated, and first correction data may be generated based on the luminance difference for each pixel.

For the test image, the control unit 128 receives input test data (DATA_TI) from the outside and transmits it to the source driver 124, and the source driver 124 converts the input test data (DATA_TI) into a signal in the form of voltage or current. This is an image displayed on the display panel 110 by applying it to the data lines. The test image contains foreign matter remaining on the display panel 110, or spotting defects due to luminance deviation due to the threshold voltage deviation of the transistor included in each pixel, changes in channel mobility, and/or deterioration of the light emitting device, etc. mura) may occur.

As an example, the output test data (DATA_TO) of the test image may be image data acquired by an imaging device shooting a test image. The imaging device may be a camera. The camera may transmit image data of a captured image of a test image displayed on the display panel 110, that is, output test data (DATA_TO), to the compensation unit 126 or the control unit 128.

The correction data generator 1263 may obtain luminance data corresponding to the luminance of each pixel for a plurality of pixels. As an example, the correction data generator 1263 may obtain luminance data corresponding to the luminance of each pixel for a plurality of pixels from the controller 128. As another example, the correction data generator 1263 may obtain luminance data corresponding to the luminance of each pixel for a plurality of pixels from an external device (not shown) that detects luminance. As another example, the control unit 128 obtains luminance data corresponding to the luminance of each pixel for a plurality of pixels from an external device (not shown), and the correction data generator 1263 obtains the luminance data from the control unit 128. can be obtained.

Luminance data may refer to data corresponding to the luminance of each pixel for a plurality of pixels. As an example, the luminance data may include data corresponding to the luminance of each pixel for all pixels included in the display panel. As another example, the luminance data may include data corresponding to the luminance of each pixel for four or more pixels among a plurality of pixels included in the display panel, but is not limited thereto.

The correction data generator 1263 may calculate a luminance difference for each pixel, which represents the difference between the detected luminance of a pixel and the reference luminance, from the luminance data. The method of calculating the luminance difference for each pixel is not particularly limited.

The correction data generator 1263 may generate correction data based on the luminance difference for each pixel. The method of generating correction data is not particularly limited.

As an example, the correction data generator 1263 may transmit correction data to the compression unit 1265. As another example, the correction data generator 1263 may store correction data in the memory 1267.

The compression unit 1265 may generate compression correction data by compressing correction data based on the luminance difference for each pixel using a quaternary tree. As an example, the compression unit 1265 may generate compression correction data by compressing the correction data using a quaternary tree and then store the compressed correction data in the memory 1267. The method by which the compression unit 1265 generates compression correction data by compressing the correction data using a quaternary tree will be described in detail below.

Additionally, the compression unit 1265 may generate compression correction data by compressing the first correction data based on the luminance difference for each pixel using the median value of the luminance difference for each pixel. As an example, the compression unit 1265 may generate compression correction data by compressing the first correction data based on the luminance difference for each pixel using the median value of the luminance difference for each pixel and store the compressed correction data in the memory 1267. A method in which the compression unit 1265 generates compression correction data by compressing the first correction data based on the luminance difference for each pixel using the median value of the luminance difference for each pixel will be described in detail below.

The memory 1267 may store correction data, compressed correction data, first correction data, or second correction data. Memory 1267 may include any non-transitory computer-readable recording medium. As an example, the memory 1267 may include random access memory (RAM), read only memory (ROM), disk drive, solid state drive (SSD), flash memory, and electrically erasable EEPROM (EEPROM) capable of updating and erasing data. It may include a permanent mass storage device such as Programmable Read Only Memory. As another example, non-perishable mass storage devices such as ROM, SSD, flash memory, disk drives, etc. may be a separate persistent storage device distinct from memory.

The decoder 1269 can read the compression correction data stored in the memory 1267, decompress it, and output it to the control unit 128. As an example, the decoder 1269 may read and decode the compression correction data compressed by the compression unit 1265 using a quaternary tree, and then obtain the correction data. As another example, the decoder 1269 may read and decode the compression correction data in which the first correction data is compressed using the median value of the luminance difference for each pixel in the compression unit 1265, and then obtain the second correction data. there is.

Generation and storage of compression correction data according to an embodiment of the present invention may be performed at regular intervals during the pre-shipment inspection stage after manufacturing the display device and/or during use of the display device after shipment.

FIG. 3 is a flowchart illustrating an example of a method for controlling luminance of a display device according to an embodiment.

Referring to FIG. 3, the compensation unit 126 may generate compressed correction data by compressing correction data using a quad-tree. As an example, the compensation unit 126 may generate compressed correction data by compressing the correction data using a quaternary tree.

In step 310, the compensator 126 may obtain luminance data corresponding to the luminance of each pixel for a plurality of pixels. As an example, the correction data generator 1263 may obtain luminance data corresponding to the luminance of each pixel for a plurality of pixels from the controller 128. As another example, the correction data generator 1263 may obtain luminance data corresponding to the luminance of each pixel for a plurality of pixels from an external device (not shown) that detects luminance. In step 320, the compensation unit ( 126) can calculate the luminance difference for each pixel, which represents the difference between the luminance for each pixel and the reference luminance, from the luminance data. As an example, the correction data generator 1263 may calculate the difference between the detected luminance and the reference luminance of each pixel from the luminance data.

The correction data generator 1263 may set the reference luminance for each pixel in the luminance table. The reference luminance may refer to the luminance that serves as a standard for correcting the detected luminance of each pixel. The reference luminance may be the detected luminance of at least one adjacent pixel among adjacent pixels in the top, bottom, left, right, and diagonal directions within a predetermined range (for example, the size of an n x n pixel array) at the position of each pixel. The position of an adjacent pixel for determining the reference luminance may be determined in advance. The reference luminance may be the average luminance of two or more adjacent pixels. As an example, the correction data generator 1263 generates a luminance distribution diagram indicating the luminance distribution of the test image, generates a luminance distribution diagram of the test image indicating the number (frequency) of pixels for each luminance, and generates a luminance distribution diagram of the test image indicating the luminance distribution of the test image, and generates a luminance distribution diagram of the test image indicating the number of pixels (frequency) for each luminance. The center luminance can be set as the reference luminance.

The correction data generator 1263 may calculate the difference between the detected luminance and the reference luminance of each pixel. As an example, the correction data generator 1263 may calculate the luminance difference for each pixel based on the difference between the detected luminance of each pixel and the central luminance of the test image.

In step 330, the compensation unit 126 may generate correction data based on the luminance difference for each pixel. As an example, the correction data generator 1263 may generate correction data based on the luminance difference for each pixel.

In step 340, the compensation unit 126 may store correction data using a 4-tree. As an example, the compression unit 1265 may generate compression correction data by compressing the correction data using a quaternary tree, and the memory 1267 may store the compression correction data. The method by which the compensation unit 126 stores correction data using a quaternary tree will be described in detail in FIG. 4 below.

Figure 4 is a flowchart illustrating an example of generating compression correction data according to an embodiment.

In step 3301, the compression unit 1265 may generate a luminance table that maps the luminance difference for each pixel of the first output image data to pixel positions based on the correction data. As an example, the compression unit 1265 may generate a luminance table indicating the luminance difference for each pixel of the first output image data. As another example, the compression unit 1265 may generate a luminance table of the test image that maps the luminance differences for each pixel of the first output image data to correspond to pixel positions. The luminance table may have the same size as the resolution of the display panel 110.

In step 3302, the compression unit 1265 may divide the luminance table into four tables. Specifically, the compression unit 1265 may divide the luminance table into four tables considering the size of the quaternary tree.

The size of the quaternary-tree corresponds to the size of a plurality of pixel arrays included in the display panel. As an example, the size of the quaternary-tree corresponds to the size of an n x n pixel array, and n may include a natural number greater than or equal to 1. As another example, the size of the quaternary-tree corresponds to the size of an m x n pixel array, and m and n may include, but are not limited to, 1 or more natural numbers that are not equal to each other.

The compression unit 1265 may divide the luminance table into four tables considering the size of the quaternary tree. Specifically, the compression unit 1265 may divide the luminance table into four tables each with the size of the quaternary tree. As an example, the compression unit 1265 converts a luminance table with a size of a 16 x 16 pixel array into four tables with a size of 8 x 8 pixel arrays using a quaternary tree with a size of an 8 x 8 pixel array. It can be divided into fields. As another example, the compression unit 1265 converts a luminance table with a size of a 16 x 8 pixel array into four tables with a size of 8 x 4 pixel arrays using a quaternary tree with a size of an 8 x 4 pixel array. It can be divided into fields.

The four tables to be divided do not necessarily have the same size, and can be divided into four tables with different pixel array sizes depending on the size of the pixel array of the luminance table. As an example, the compression unit 1265 converts a luminance table with a size of an 8 x 8 pixel array into a 5 x 3 pixel array, a 3 x 3 pixel array, a 5 x 5 pixel array, and 3 x 5 pixels. Using a quaternary tree with the size of the array, it can be divided into four tables with different pixel array sizes.

In step 3303, the compression unit 1265 may calculate the inter-pixel luminance difference for each of the divided tables by comparing the luminance difference for each pixel within the table.

The luminance difference between pixels may refer to a value obtained by comparing the luminance differences for each pixel of pixels existing in each divided table. As an example, the luminance difference between pixels may refer to a value obtained by comparing the luminance difference for each pixel on a pixel basis. As another example, the luminance difference between pixels may refer to a value obtained by comparing the luminance difference in units of blocks including a predetermined number of pixels.

In step 3304, the compression unit 1265 may modify the luminance table by setting the luminance difference for each pixel within the table as one value for the table in which the luminance difference between pixels is within a threshold value.

The threshold may be determined by considering the capacity of the memory of the display device and the luminance of each pixel corrected using correction data. The lower the threshold, the larger the memory capacity of the display device occupied by the compression correction data, but the higher the accuracy of the luminance of each pixel corrected using the correction data. On the other hand, the higher the threshold, the smaller the memory capacity of the display device occupied by the compression correction data, but the lower the accuracy of the luminance of each pixel corrected using the correction data.

In step 3305, the compression unit 1265 divides a table in which the luminance difference between pixels exceeds the threshold and has an array size of 4 or more pixels until the luminance difference between pixels is within the threshold. The steps of calculating the luminance difference between pixels and modifying the luminance table may be additionally performed.

Specifically, the compression unit 1265 selects the pixel for a table in which the luminance difference between pixels exceeds a threshold and has an array size of 4 or more pixels, for example, a table with an 8 x 8 pixel array size. Until the luminance difference between pixels is within the threshold, it is further divided into 4 tables with the size of a 4 x 4 pixel array, and the luminance difference between pixels is calculated within the table with the size of the 4 x 4 pixel array, and if If the luminance difference between pixels in a table with the size of a 4 x 4 pixel array is within the threshold, the luminance table is modified by setting the luminance difference for each pixel in the table to one value. This process is further performed until the luminance difference between pixels in the divided table is within the threshold. However, the step of dividing the table cannot proceed any further if the number of pixels is 3 or less. This will be explained in detail in step 3306 below.

In step 3306, the compression unit 1265 may no longer divide the table in which the luminance difference between pixels exceeds the threshold and the size of the array of pixels is three or less.

For a table in which the luminance difference between pixels exceeds the threshold and the size of the array of pixels is less than 3, it can no longer be divided into 4 tables. Therefore, do not correct the pixel-specific luminance difference of 3 or less pixels, or select the average value of the pixel-specific luminance difference of 3 or less pixels and set the pixel-specific luminance difference of 3 or less pixels as one value. You can modify the luminance table or select one pixel-specific luminance difference among the pixel-specific luminance differences of 3 or less pixels and set the pixel-specific luminance difference of 3 or less pixels to one value, but are not limited to this. .

In step 3307, the compression unit 1265 may generate compression correction data based on the modified luminance table.

Once the luminance table has been modified through the above-described steps, the compression unit 1265 generates compression correction data based on the modified luminance table. Accordingly, the amount of data in the generated compressed correction data is reduced compared to the initial correction data. As a result, the cost increase due to the addition of a compensation circuit can be minimized by integrating the low-capacity memory into the driving chip.

Hereinafter, with reference to FIGS. 5 and 6, an example in which the compression unit 1265 generates compression correction data by dividing the luminance table according to an embodiment using a quaternary tree will be described. The method of generating compression correction data by dividing the luminance table using a quaternary tree according to an embodiment described here is the same as the above-described method, so detailed details will be omitted.

FIG. 5 is a diagram illustrating an example of generating compression correction data using a quaternary tree in one embodiment.

FIG. 6 is a diagram illustrating an example of a quaternary tree used when generating compression correction data according to an embodiment.

Referring to FIG. 5, it can be seen that the luminance table corresponding to the size of the 16 x 16 pixel array is divided into tables corresponding to the sizes of different pixel arrays, each named with the alphabet from A to S.

Referring to FIG. 6, a tree structure corresponding to the size of each different pixel array, each named with the alphabet from A to S, can be seen.

First, the compression unit 1265 divides the luminance table corresponding to the size of the 16 x 16 pixel array into four tables corresponding to the size of the 8 x 8 pixel array. And the compression unit 1265 calculates the luminance difference between pixels by comparing the luminance difference for each pixel in the table corresponding to the size of each 8 x 8 pixel array. At this time, for the A table, since the luminance difference between pixels falls within the threshold, the compression unit 1265 modifies the luminance table by setting the luminance difference for each pixel to one value without further dividing. For the tables corresponding to the remaining 8 The steps of dividing the tables until the values are within the range, calculating the luminance difference between pixels, and modifying the luminance table are additionally performed. Accordingly, the compression unit 1265 contains tables (B, C, D, E, F, G, H, I, J, R) corresponding to the size of the 4 x 4 pixel array in which the luminance difference between pixels is within the threshold. , S) is not further divided and the luminance table is modified by setting the luminance difference for each pixel to one value. Then, the compression unit 1265 divides the table corresponding to the size of the 4 x 4 pixel array in which the luminance difference between pixels exceeds the threshold into a table corresponding to the size of the 2 x 2 pixel array. Likewise, the compression unit 1265 does not further divide the tables (O, P, Q) corresponding to the size of the 2 x 2 pixel array in which the luminance difference between pixels is within the threshold, but converts the luminance difference for each pixel into one value. Set to modify the luminance table. Then, the compression unit 1265 divides the table corresponding to the size of the 2 x 2 pixel array in which the luminance difference between pixels exceeds the threshold into the table (K, L, M, N) corresponding to the size of the 1 x 1 pixel array. Divide into At this time, the compression unit 1265 does not further divide the K, L, M, and N tables, and does not modify the luminance table for the luminance difference for each pixel, or selects the luminance difference for each pixel and selects the K, L , M, N The luminance table corresponding to the table area can be stored as one value.

FIG. 7 is a diagram for explaining an example of the size of a quaternary tree according to an embodiment.

The size of the quaternary-tree corresponds to the size of a plurality of pixel arrays included in the display panel. As an example, the size of the quaternary-tree corresponds to the size of an n x n pixel array, and n may include a natural number greater than or equal to 1. As another example, the size of the quaternary-tree corresponds to the size of an m x n pixel array, and m and n may include, but are not limited to, 1 or more natural numbers that are not equal to each other.

FIG. 8 is a flowchart illustrating an example of storing first correction data using the median value of the luminance difference for each pixel, according to an embodiment.

In step 810, the compensator 126 may obtain luminance data corresponding to the luminance of each pixel for four or more pixels among the plurality of pixels included in the display panel.

The control unit 128 may obtain first output image data by applying input image data to a display panel including a plurality of pixels. Specifically, the control unit 128 receives input test image data from the outside and controls the scan driver 122 and the source driver 124 to apply the input test image data to the pixels (PX) of the display panel 110. By doing so, the test image can be displayed on the display panel 110 to obtain first output image data. The compensation unit 126 may obtain luminance data corresponding to the luminance of each pixel based on the first output image data from the control unit 128.

The compensator 126 may acquire luminance data corresponding to the luminance of four or more pixels. As an example, the correction data generator 1263 may obtain luminance data corresponding to the luminance of four or more pixels based on the output test data (DATA_TO). As another example, when the correction data generator 1263 divides the table corresponding to a plurality of pixels included in the display panel into one or more regions, the correction data generation unit 1263 divides the table corresponding to the plurality of pixels included in the display panel into one or more regions, corresponding to the luminance of each pixel for four or more pixels present in the region. luminance data can be obtained.

The four or more pixels may include four or more pixels present in the area when the table corresponding to the plurality of pixels included in the display panel is divided into at least one area.

The size of the area corresponds to the size of an n x m pixel array, and n and m may include natural numbers of 1 or more. As an example, the size of the area corresponds to the size of an n x n pixel array, and n may include a natural number of 1 or more. As another example, the size of the area corresponds to the size of an m x n pixel array, and m and n may include natural numbers of 1 or more that are not the same, but are not limited thereto.

Additionally, the size of the area may be determined by considering the capacity of the memory of the display device and the luminance of each pixel corrected using data for luminance correction. As the size of the area becomes smaller, the memory capacity of the display device occupied by the compression correction data increases, but the accuracy of the luminance of each pixel corrected using the correction data increases. On the other hand, the larger the size of the area, the smaller the memory capacity of the display device occupied by the compression correction data, but the lower the accuracy of the luminance of each pixel corrected using the correction data.

Referring again to FIG. 8 , in step 820, the compensator 126 may calculate a luminance difference for each pixel, which represents the difference between the luminance for each pixel and the reference luminance, from the luminance data. As an example, the correction data generator 1263 may calculate a luminance difference for each pixel, which represents the difference between the luminance for each pixel and the reference luminance. Since the reference luminance is the same as that described in step 320 of FIG. 3, redundant description will be omitted.

Hereinafter, with reference to FIG. 11 , an example in which the correction data generator 1263 calculates the luminance difference for each pixel, which represents the difference between the luminance for each pixel and the reference luminance, will be described.

FIG. 11 is a diagram illustrating an example of the luminance of four pixels and the difference in luminance of each pixel according to an embodiment.

The correction data generator 1263 acquires luminance data corresponding to the luminance (156, 152, 157, 118) of each of the four pixels existing in an area with a size of 16 x 16. Then, the correction data generator 1263 calculates the luminance difference (-28, -24, -29, 10) for each pixel, which represents the difference between the luminance for each pixel and the reference luminance.

In Figure 11, the luminance of each 4 pixels is shown in an area of 16 x 16 in size. However, the luminance is not limited to this and the luminance difference for each pixel can be calculated by obtaining luminance data corresponding to the luminance of 5 or more pixels.

Referring again to FIG. 8, in step 830, the compensator 126 generates first correction data based on the luminance difference for each pixel. As an example, the correction generator 1263 generates first correction data based on the luminance difference for each pixel.

In step 840, the compensator 126 may store the first correction data using the median value of the luminance difference for each pixel. As an example, the compression unit 1265 generates compression correction data by compressing the first correction data using the median value of the luminance difference for each pixel, and the memory 1267 stores the compression correction data.

Hereinafter, with reference to FIG. 9, an example of generating compression correction data by compressing the first correction data using the median value of the luminance difference for each pixel will be described.

Figure 9 is a flowchart illustrating an example of generating compression correction data according to an embodiment.

In step 8401, the compression unit 1265 calculates the median value of the luminance difference for each pixel present in the first correction data. As an example, the median value may refer to the average value of the luminance difference for each pixel. As another example, the median value may refer to the average value of the largest and smallest values of the luminance difference for each pixel. As another example, the median value may refer to a value located at the center of the entire pixel when the luminance difference between pixels is arranged in order of size.

In step 8402, the compression unit 1265 calculates a difference value by subtracting the median value from the luminance difference for each pixel.

In step 8403, the compression unit 1265 generates compression correction data based on the median and difference values.

Hereinafter, an example in which the compression unit 1265 generates compression correction data using the intermediate value will be described in FIG. 12.

FIG. 12 is a diagram illustrating an example of generating compression correction data using an intermediate value according to an embodiment.

Referring to FIG. 12, an example can be seen in which the difference value is calculated by subtracting the median value of 10 from the pixel luminance differences of 9, 9, 10, and 10. The median value can be calculated from the luminance difference for each pixel using various methods as described above, and in Figure 12, the median value corresponds to 10.

The compression unit 1265 may generate compression correction data consisting of the median and difference values by calculating the median and difference values from the first correction data. Compressed correction data consisting of median and difference values has the advantage of reducing memory capacity by using saved storage space compared to the first correction data.

Hereinafter, an example in which the compensation unit 126 obtains second correction data by decoding compression correction data using linear interpolation will be described in FIG. 10.

FIG. 10 is a flowchart illustrating an example of decoding using a linear interpolation method according to an embodiment.

In step 1101, the decoder 1269 calculates the luminance difference for each of four or more pixels based on the median and difference values. In Figures 9 and 12, the median and difference values were calculated from the luminance difference for each pixel. Using this inversely, the decoder 1269 calculates the luminance difference for each pixel from the median value and the difference value. The calculated luminance difference for each pixel may be the same as the luminance difference for 4 or more pixels calculated in step 830.

In step 1102, the decoder 1269 generates a luminance table that maps the luminance differences for each of four or more pixels to pixel positions.

In step 1103, the decoder 1269 selects the luminance difference between any two pixels within the same y-axis among the luminance differences between four or more pixels and calculates the luminance difference between pixels within the same y-axis using linear interpolation.

In step 1104, the decoder 1269 selects the luminance difference between any two pixels within the same x-axis among the luminance differences between four or more pixels and the luminance difference between pixels within the same y-axis and uses linear interpolation to determine the luminance difference between pixels within the same x-axis. Calculate the luminance difference for each pixel.

In step 1105, the decoder 1269 obtains second correction data based on the luminance difference between four or more pixels, the luminance difference between pixels within the same y-axis, and the luminance difference between pixels within the same x-axis.

Hereinafter, with reference to FIG. 13, an example in which the decoder 1269 decodes compression correction data using linear interpolation will be described.

Figure 13 is a diagram for explaining an example of decoding using linear interpolation.

First, the decoder 1269 can select the luminance difference between any two pixels within the same y-axis among the luminance differences between four or more pixels and calculate the luminance difference between pixels within the same y-axis using linear interpolation. At x _i = 0 and x _i = 16, linear interpolation can be performed on the y-axis, respectively, to calculate the luminance difference for each pixel within the same y-axis. When x _i is 0, the luminance difference for each pixel with values of -28 and -29 can be used to calculate the luminance difference for each pixel within the y-axis where x _i is 0 through linear interpolation. When x _i is 16, the luminance difference for each pixel with values of -24 and 10 can be used to calculate the luminance difference for each pixel within the y-axis where x _i is 16 through linear interpolation.

Then, the decoder 1269 selects the luminance difference between any two pixels within the same x-axis among the luminance differences between four or more pixels and the luminance difference between pixels within the same y-axis, and uses linear interpolation to determine the luminance difference between pixels within the same x-axis. The luminance difference can be calculated. From y _i = 0 to y _i = 16, linear interpolation can be performed on the x-axis to calculate the luminance difference for each pixel within the same x-axis.

Additionally, the decoder 1269 may obtain second correction data based on the luminance difference between four or more pixels, the luminance difference between pixels within the same y-axis, and the luminance difference between pixels within the same x-axis. The decoder 1269 may obtain second correction data from the luminance table corresponding to the size of the 16 x 16 pixel array.

Figure 14 is a block diagram showing another example of a display device according to an embodiment.

Referring to FIG. 14, the display device 20 according to one embodiment may be a multi-display device in which a plurality of first to nth display modules 110_1 to 110_n are arranged adjacently. A large display device can be implemented by combining a plurality of display modules. The display device 20 can be used on an electronic signboard that displays commercial and public information indoors or outdoors in performance halls, exhibition halls, stock exchanges, department stores, hospitals, playgrounds, railroads, airports, highways, homes, etc.

The first to nth display modules 110_1 to 110_n of the display device 20 may each independently display individual images or may be integrated to display one image. Each of the first to nth display modules 110_1 to 110_n may be a display panel 110 of the display device 10 shown in FIG. 1 .

The first to nth display modules 110_1 to 110_n may be arranged horizontally and vertically at regular intervals. The first to nth display modules 110_1 to 110_n may be in contact with each other and may be spaced apart by a gap less than or equal to the width of the black matrix (not shown).

The first to nth display modules 110_1 to 110_n may be arranged in the same size and/or same shape. The first to nth display modules 110_1 to 110_n may be arranged in a square, rectangular, or polygonal shape. As another example, at least one of the first to nth display modules 110_1 to 110_n may have a different size and/or a different shape.

The display device 20 may include a driver 120B that controls the first to nth display modules 110_1 to 110_n. The driving unit 120B controls the first to nth driving units 120_1 to 120_n and the first to nth driving units 120_1 to 120_n, which independently control the first to nth display modules 110_1 to 110_n, respectively. It may include a second control unit 130.

Each of the first to nth drivers 120_1 to 120_n may include a scan driver 122_1, a source driver 124_1, a first control unit 128_1, and a compensation unit 126_1. Since the components of each of the first to nth driving units 120_1 to 120_n are the same as those of the driving unit 120A shown in FIG. 1, detailed descriptions are omitted. Each of the first to nth driving units 120_1 to 120_n may further include a sensing unit like the driving unit 120A shown in FIG. 2 .

Each of the first to nth driving units 120_1 to 120_n may perform luminance correction of the corresponding first to nth display modules 110_1 to 110_n by the above-described method.

A luminance difference may occur between the first to nth display modules 110_1 to 110_n. The second control unit 130 may generate and provide data for luminance correction to correct the luminance difference between the first to nth driving units 120_1 to 120_n and the first to nth display modules 110_1 to 110_n.

As an example, each of the first to nth drivers 120_1 to 120_n displays a test image on a corresponding display module among the first to nth display modules 110_1 to 110_n, and displays the pixel-specific luminance for a plurality of pixels. Data for luminance correction by acquiring luminance data corresponding to can be created.

As another example, each of the first to nth drivers 120_1 to 120_n displays a test image on a corresponding display module among the first to nth display modules 110_1 to 110_n, and displays the pixel-specific luminance for a plurality of pixels. Brightness is corrected by acquiring luminance data corresponding to the luminance data, calculating the luminance difference for each pixel from the luminance data, generating correction data based on the luminance difference for each pixel, and storing the correction data using the median value of the luminance difference for each pixel. Data can be created for .

Input test image data input to each of the first to nth display modules 110_1 to 110_n may be the same image data. Each of the first to nth driving units (120_1 to 120_n) corrects luminance based on the difference between the detected luminance of the pixel obtained from the test image in the corresponding first to nth display modules (110_1 to 110_n) and the first reference luminance. Data can be generated for . The first reference luminance may be the luminance of at least one adjacent pixel or the central luminance of the test image.

The second control unit 130 may receive the global brightness (GB) of the test image displayed on the first to nth display modules 110_1 to 110_n from the first to nth driving units 120_1 to 120_n. The global luminance (GB) may be the average luminance of the test image or the central luminance in the luminance distribution of the test image.

The second control unit 130 generates global luminance correction data for each display module to correct the global luminance difference between the first to nth display modules 110_1 to 110_n and outputs the global luminance correction data to the first to nth driving units 120_1 to 120_n, respectively. can be provided. Global luminance correction data may be an offset value or gain value for all pixels.

Each of the first to nth drivers 120_1 to 120_n may correct the luminance of input image data using luminance correction data (CD) and global luminance correction data. The first control unit of each of the first to nth driving units 120_1 to 120_n converts the input image data DATA into corrected image data DATA' using data for luminance correction (CD) and global luminance correction data. You can.

The second control unit 130 generates data for each display module to correct the average luminance or center luminance received from the first to nth display modules 110_1 to 110_n to the second reference luminance, and outputs data to the first to nth driving units (110_1 to 110_n). 120_1 to 120_n) can be provided respectively. The second reference luminance may be one of the average luminances or the center luminance of the first to nth display modules 110_1 to 110_n. The second reference luminance may be any luminance set by the user.

Figure 15 is a luminance distribution diagram for test images of a plurality of display modules according to an embodiment.

The central luminance (CB1) of the first display module (110_1) and the central luminance (CB2) of the n-th display module (110_n) are different. Accordingly, the global luminance of the first display module 110_1 and the n-th display module 110_n may be different, resulting in a luminance difference between the first display module 110_1 and the n-th display module 110_n.

The second control unit 130 generates data for each display module to correct the center luminance of the first to nth display modules 110_1 to 110_n to the reference center luminance (RB) and outputs data to the first to nth drive units 120_1 to 120_n. ) can be provided separately. The reference central luminance (RB) may be one of the central luminances (CB) of the first to nth display modules (110_1 to 110_n). The reference center luminance (RB) may be any luminance set by the user.

The display device 20 can ensure luminance uniformity between the first to nth display modules 110_1 to 110_n by correcting the luminance difference between the first to nth display modules 110_1 to 110_n.

The display device 20 can individually correct the luminance of the first to nth display modules 110_1 to 110_n and uniformly adjust the luminance between the first to nth display modules 110_1 to 110_n.

The display devices 10 and 20 according to an embodiment of the present invention store correction data for correcting the luminance of a data signal in the built-in memory of the driving unit. As an example, compressed correction data in which correction data is compressed using a quaternary tree may be stored in the internal memory. As another example, compression correction data obtained by compressing the first correction data using the median value of the luminance difference for each pixel may be stored in the internal memory. Additionally, the display devices 10 and 20 according to an embodiment of the present invention can obtain second correction data by decoding the compression correction data using linear interpolation. As a result, it is possible to solve the problem of high costs caused by providing a storage means for storing luminance deviation information of all pixels of the display device and a storage means for storing compression correction data corresponding thereto, separately from the driver 120. That is, embodiments of the present invention can meet the requirements for price and miniaturization by minimizing memory capacity while embedding only a single memory in the driving unit.

In the above-described embodiments, the luminance difference is calculated on a pixel basis, but the embodiment of the present invention is not limited to this, and the luminance difference can be calculated on a block basis including a predetermined number of pixels.

Claims (14)

Obtaining luminance data corresponding to pixel-specific luminance for a plurality of pixels;
calculating a luminance difference for each pixel representing a difference between the luminance for each pixel and a reference luminance from the luminance data;
generating correction data based on the luminance difference for each pixel; and
A luminance control method for a display device comprising: storing the correction data using a quad-tree. According to claim 1,
The size of the quaternary-tree corresponds to the size of the nxn pixel array,
The method wherein n includes a natural number of 1 or more. According to claim 1,
The size of the quaternary-tree corresponds to the size of the mxn pixel array,
The method wherein m and n include natural numbers of 1 or more that are not equal to each other. According to claim 1,
The saving step is,
A method comprising: storing compression correction data obtained by compressing the correction data using a quaternary tree. According to clause 4,
The step of storing the compression correction data is,
generating a luminance table mapping the luminance difference for each pixel to a pixel position based on the correction data;
Splitting the table into four tables considering the size of the quaternary tree;
For each of the divided tables, calculating a luminance difference between pixels by comparing luminance differences for each pixel existing in the table;
For a table in which the luminance difference between pixels is within a threshold, modifying the luminance table by setting the luminance difference for each pixel in the table to one value;
For a table in which the luminance difference between pixels exceeds a threshold and the size of an array of four or more pixels, dividing until the luminance difference between pixels is within the threshold, calculating the luminance difference between pixels additionally performing the steps of: and modifying the luminance table;
For a table in which the luminance difference between pixels exceeds a threshold and the size of the array of pixels is three or less, not further dividing the table; and
A method comprising: generating compression correction data based on the modified luminance table. According to clause 5,
The method wherein the threshold value is determined considering the capacity of the memory occupied by the compression correction data and the luminance of each pixel corrected using the correction data. According to clause 6,
The obtaining step is,
Obtaining first output image data by applying input image data to a display panel including a plurality of pixels;
Detecting luminance for each pixel from the first output image data, and obtaining luminance data corresponding to the luminance for each pixel. According to clause 7,
The method further comprising: decoding the compression correction data to obtain the correction data. According to clause 8,
Converting the input image data using the correction data to generate correction image data. The method further comprising: According to clause 9,
The method further comprising: obtaining second output image data corresponding to the corrected image data. a display panel including a plurality of pixels forming at least one row and column;
a control unit configured to apply input image data to the display panel to obtain first output image data, and obtain luminance data corresponding to luminance for each pixel based on the first output image data; and
a compensation unit that calculates a pixel-wise luminance difference between the pixel-wise luminance and a reference luminance from the luminance data, generates correction data based on the pixel-wise luminance difference, and stores the correction data using a quaternary tree; A display device containing a. According to claim 11,
The compensation department,
Generating a luminance table mapping the luminance difference for each pixel to a pixel location based on the correction data,
Divide the table into four tables considering the size of the quaternary tree,
For each of the divided tables, calculate the luminance difference between pixels by comparing the luminance difference for each pixel existing in the table,
For a table in which the luminance difference between pixels is within a threshold value, modify the luminance table by setting the luminance difference for each pixel in the table to one value,
For a table in which the luminance difference between pixels exceeds a threshold and has an array size of 4 or more pixels, the division is performed until the luminance difference between pixels is within the threshold,
Additional steps of calculating the luminance difference between pixels and modifying the luminance table are performed,
For a table in which the luminance difference between pixels exceeds the threshold and the size of the array of pixels is 3 or less, no further division is performed,
A display device that generates compression correction data based on the modified luminance table. According to claim 11,
a scan driver that outputs scan signals to a plurality of pixels included in the display panel; and
The display device further comprising a source driver that outputs image data to a plurality of pixels included in the display panel. According to claim 11,
The display device includes a plurality of display panels connected to each other,
Global luminance of output image data corresponding to the input image data is provided from each of the plurality of display panels, and global luminance correction data that corrects the difference in global luminance of the plurality of display panels is sent to each of the plurality of display panels. A display device further comprising a second control unit providing a second control unit.

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