Method of compensating for luminance of display device

A method of compensating for luminance of a display device includes determining position compensation values of each of panel blocks for measurement grayscale values based on a difference between luminance of a reference panel block and luminance of the each of the panel blocks for the measurement grayscale values, generating a first gamma curve for a first driving frequency and the position compensation values of the each of the panel blocks for the measurement grayscale values, generating a second gamma curve for a second driving frequency and the luminance of the panel blocks for the measurement grayscale values at the first driving frequency, and compensating for input image data based on the first gamma curve and the second gamma curve.

PRIORITY STATEMENT

This application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2022-0015046, filed on Feb. 4, 2022, in the Korean Intellectual Property Office KIPO, the contents of which are herein incorporated by reference in their entireties.

BACKGROUND

Embodiments of the present inventive concept relate to a method of compensating for luminance of a display device. More particularly, embodiments of the present inventive concept relate to a method of compensating for luminance of a display device that support variable frame mode.

2. Description of the Related Art

Generally, a display device may display an image with a constant driving frequency of 60 Hz or higher. However, a rendering frequency of rendering by a host processor (e.g., a graphic processing unit (GPU), etc.) that provides input image data to the display device may not match the driving frequency of the display device. A tearing phenomenon in which a boundary line is generated in the image displayed on the display device may occur due to frequency mismatch.

To prevent such a tearing phenomenon, a variable frame mode in which the rendering frequency of the host processor and the driving frequency of the display device are synchronized (e.g., Free-Sync mode, G-Sync mode, etc.) has been developed.

However, in the display device operating in the variable frame mode, luminance of the display panel may not be uniform at different driving frequencies.

SUMMARY

Embodiments of the present inventive concept provide a method of compensating for a display device generating gamma curves for driving frequencies.

According to embodiments of the present inventive concept, a method of compensating for luminance of a display device may include determining position compensation values of each of panel blocks for measurement grayscale values based on a difference between luminance of a reference panel block and luminance of the each of the panel blocks for the measurement grayscale values, generating a first gamma curve for a first driving frequency based on luminance of the panel blocks for the measurement grayscale values at the first driving frequency and the position compensation values of the each of the panel blocks for the measurement grayscale values, generating a second gamma curve for a second driving frequency different from the first driving frequency based on a difference between luminance of the panel blocks for the measurement grayscale values at the second driving frequency and the luminance of the panel blocks for the measurement grayscale values at the first driving frequency, and compensating for input image data based on the first gamma curve and the second gamma curve.

In an embodiment, determining the position compensation values of the each of the panel blocks may include determining a first position compensation value of each of the panel blocks for a first measurement grayscale value based on a difference between luminance of the reference panel block for the first measurement grayscale value and luminance of the each of the panel blocks for the first measurement grayscale value, determining a second position compensation value of each of the panel blocks for the second measurement grayscale value based on a difference between luminance of the reference panel block for the second measurement grayscale value and luminance of the each of the panel blocks for the second measurement grayscale value, and determining the position compensation value of each of the panel blocks for other measurement grayscale values other than the first measurement grayscale value and the second measurement grayscale value among the measurement grayscale values based on the first position compensation value and the second position compensation value.

In an embodiment, the position compensation value of each of the panel blocks for the other measurement grayscale values may be determined by using

LC=C×(G-G⁢2G⁢1-G⁢2)u×(LC⁢1-LC⁢2)+LC⁢2,
where LC is the position compensation value of the each of the panel blocks for the other measurement grayscale values, C is a first characteristic coefficient, G is the other measurement grayscale values, G1is the first measurement grayscale value, G2is the second measurement grayscale value, u is a second characteristic coefficient, LC1is the first position compensation value, and LC2is the second position compensation value.

In an embodiment, the determining the position compensation value of the each of the panel blocks may include determining a third position compensation value of each of first panel blocks for a first measurement grayscale value based on a difference between luminance of the reference panel block for the first measurement grayscale value and luminance of the each of the first panel blocks for the first measurement grayscale value, determining a fourth position compensation value of each of second panel blocks for the first measurement grayscale value based on a difference between the luminance of the reference panel block for the first measurement grayscale value and luminance of the each of the second panel blocks for the first measurement grayscale value, determining a fifth position compensation value of each of the first panel blocks for a second measurement grayscale value based on a difference between luminance of the reference panel block for the second measurement grayscale value and luminance of the each of the first panel blocks for the second measurement grayscale value, determining a sixth position compensation value of each of the second panel blocks for third measurement grayscale value based on a difference between luminance of the reference panel block for the third measurement grayscale value and luminance of the each of the second panel blocks for the third measurement grayscale value, determining position compensation values of each of the first panel blocks for first other measurement grayscale values other than the first measurement grayscale value and the second measurement grayscale value among the measurement grayscale values based on the third position compensation value and the fifth position compensation value, and determining position compensation values of each of the second panel blocks for second other measurement grayscale values other than the first measurement grayscale value and the third measurement grayscale value among the measurement grayscale values based on the fourth position compensation value and the sixth position compensation value.

In an embodiment, the position compensation value of the each of the first panel blocks for the first other measurement grayscale values may be determined by using

LCA=C×(G-G⁢2G⁢1-G⁢2)u×(LC⁢3-LC⁢5)+LC⁢5,
where LCA is the position compensation value of the each of the first panel blocks for the first other measurement grayscale values, C is a first characteristic coefficient, G is the first other measurement grayscale values, G1is the first measurement grayscale value, G2is the second measurement grayscale, u is a second characteristic coefficient, LC3is the third position compensation value, and LC5is the fifth position compensation value. The position compensation value of the each of the second panel blocks for the second other measurement grayscale values may be determined by using

LCB=C×(G-G⁢1G⁢3-G⁢1)u×(LC⁢5-LC⁢4)+LC⁢4,
where LCB is the position compensation value of the each of the second panel blocks for the second other measurement grayscale values, C is the first characteristic coefficient, G is the second other measurement grayscale values, G1is the first measurement grayscale value, G3is the third measurement grayscale value, u is the second characteristic coefficient, LC6is the sixth position compensation value, and LC4is the fourth position compensation value.

In an embodiment, the first characteristic coefficient and the second characteristic coefficient may be calculated through artificial intelligence learning.

In an embodiment, determining the position compensation value of the each of the panel blocks may include displaying the third measurement grayscale value to the reference panel block, the first measurement grayscale value to the first panel blocks, and the third measurement grayscale value to the second panel blocks in a first measurement period of the first driving frequency, displaying the second measurement grayscale value to the first panel blocks, and the first measurement grayscale value to the second panel blocks in a second measurement period of the first driving frequency, and displaying the first measurement grayscale value to the reference panel block and the different measurement grayscale values to the first panel blocks and the second panel blocks in a third measurement period of the first driving frequency.

In an embodiment, the first gamma curve may be generated by adding the position compensation value of each of the panel blocks for the measurement grayscale values to luminance of the panel blocks for the measurement grayscale values measured in the third measurement period.

In an embodiment, generating the second gamma curve may include displaying the measurement grayscale values to the panel blocks in a same manner as in the third measurement period, in a fourth measurement period of the second driving frequency, and generating the second gamma curve by adding the position compensation value of each of the panel blocks for the measurement grayscale values to luminance of the panel blocks for the measurement grayscale values measured in the fourth measurement period.

In an embodiment, the first measurement grayscale may be greater than the second measurement grayscale and is smaller than the third measurement grayscale, the first panel blocks may be disposed to surround the reference panel blocks, and the second panel blocks may be disposed to surround the first panel blocks.

In an embodiment, the measurement grayscale values displayed on the first panel blocks may be smaller than the measurement gray scale values displayed on the second panel blocks in the third measurement period.

In an embodiment, the compensating for the input image data may include generating gamma curves for frequencies other than the first driving frequency and the second driving frequency based on the first gamma curve and the second gamma curve, and compensating for the input image data by a difference between the first gamma curve and gamma curves other than the first gamma curve.

In an embodiment, the first driving frequency may be greater than the second driving frequency.

According to embodiments, a method of compensating for luminance of a display device may include determining position compensation values of each of panel blocks for measurement grayscale values based on a difference between luminance of a reference panel block and luminance of the each of the panel blocks for the measurement gray scale values, generating a first gamma curve for a first driving frequency based on luminance of the panel blocks for the measurement grayscale values at the first driving frequency and the position compensation values of the each of the panel blocks for the measurement grayscale values, generating a second gamma curve for a second driving frequency different from the first driving frequency based on a difference between luminance of the panel blocks for the measurement grayscale values at the second driving frequency and the luminance of the panel blocks for the measurement grayscale values at the first driving frequency, generating a third gamma curve for a third driving frequency different from the first driving frequency and the second driving frequency based on a difference between luminance of the panel blocks for the measurement grayscale values at the third driving frequency and the luminance of the panel blocks for the measurement grayscale values at the first driving frequency, and compensating for input image data based on the first gamma curve, the second gamma curve, and the third gamma curve.

In an embodiment, the determining the position compensation values of the each of the panel blocks may include determining a third position compensation value of each of first panel blocks for a first measurement grayscale value based on a difference between luminance of the reference panel block for the first measurement grayscale value and luminance of the each of the first panel blocks for the first measurement grayscale value, determining a fourth position compensation value of each of second panel blocks for the first measurement grayscale value based on a difference between the luminance of the reference panel block for the first measurement grayscale value and luminance of the each of the second panel blocks for the first measurement grayscale value, determining a fifth position compensation value of each of the first panel blocks for a second measurement grayscale value based on a difference between luminance of the reference panel block for the second measurement grayscale value and luminance of the each of the first panel blocks for the second measurement grayscale value, determining a sixth position compensation value of each of the second panel blocks for a third measurement grayscale value based on a difference between luminance of the reference panel block for the third measurement grayscale value and luminance of the each of the second panel blocks for the third measurement grayscale value, determining position compensation values of each of the first panel blocks for first other measurement grayscale values other than the first measurement grayscale value and the second measurement grayscale value among the measurement grayscale values based on the third position compensation value and the fifth position compensation value, and determining position compensation values of each of the second panel blocks for second other measurement grayscale values other than the first measurement grayscale value and the third measurement grayscale value among the measurement grayscale values based on the fourth position compensation value and the sixth position compensation value.

In an embodiment, the determining the position compensation values of each of the panel blocks may include displaying the third measurement grayscale value to the reference panel block, the first measurement grayscale value to the first panel blocks, and the third measurement grayscale value to the second panel blocks in a first measurement period of the first driving frequency, displaying the second measurement grayscale value to the first panel blocks and the first measurement grayscale value to the second panel blocks in a second measurement period of the first driving frequency, and displaying the first measurement grayscale value to the reference panel block and the different measurement grayscale values to the first panel blocks and the second panel blocks, in a third measurement period of the first driving frequency.

In an embodiment, the first gamma curve may be generated by adding the position compensation values of each of the panel blocks for the measurement grayscale values to luminance of the panel blocks for the measurement grayscale values measured in the third measurement period.

In an embodiment, the generating the second gamma curve may include displaying the same measurement grayscale values as the third measurement period to the panel blocks in a fourth measurement period of the second driving frequency, and generating the second gamma curve by adding the position compensation values of each of the panel blocks for the measurement grayscale values to luminance of the panel blocks for the measurement grayscale values measured in the fourth measurement period. The generating the third gamma curve may include displaying the same measurement grayscale values as the third measurement period to the panel blocks in a fifth measurement period of the third driving frequency, and generating the third gamma curve by adding the position compensation values of each of the panel blocks for the measurement grayscale values to luminance of the panel blocks for the measurement grayscale values measured in the fifth measurement period.

In an embodiment, the compensating for the input image data may include generating gamma curves for frequencies other than the first driving frequency, the second driving frequency, and the third driving frequency based on the first gamma curve, the second gamma curve, and the third gamma curve, and compensating for the input image data by a difference between the first gamma curve and gamma curves other than the first gamma curve.

In an embodiment, the first driving frequency may be greater than the second driving frequency and the third driving frequency.

Therefore, the method may generate gamma curves for driving frequencies by determining position compensation values of each of panel blocks for measurement grayscale values based on a difference between luminance of a reference panel block and luminance of the each of the panel blocks for the measurement grayscale values, generating a first gamma curve for a first driving frequency based on luminance of the panel blocks for the measurement grayscale values at the first driving frequency and the position compensation values of the each of the panel blocks for the measurement grayscale values, generating a second gamma curve for a second driving frequency different from the first driving frequency based on a difference between luminance of the panel blocks for the measurement grayscale values at the second driving frequency and the luminance of the panel blocks for the measurement grayscale values at the first driving frequency, and compensating for input image data based on the first gamma curve and the second gamma curve. Accordingly, the display device may compensate for a difference in luminance according to the driving frequency.

In addition, the method may more accurately compensate for a difference in luminance according to a driving frequency than when compensating for input image data only based on a first gamma curve and a second gamma curve by generating a third gamma curve for a third driving frequency different from the first driving frequency and the second driving frequency based on a difference between luminance of the panel blocks for the measurement grayscale values at the third driving frequency and the luminance of the panel blocks for the measurement grayscale values at the first driving frequency.

However, the effects of the present inventive concept are not limited to the above-described effects, and may be variously expanded without departing from the spirit and scope of the present inventive concept.

DETAILED DESCRIPTION OF THE INVENTIVE CONCEPT

Hereinafter, the present inventive concept will be explained in detail with reference to the accompanying drawings.

FIG.1is a block diagram illustrating a display device1000according to embodiments of the present inventive concept.

Referring toFIG.1, the display device1000may include a display panel100, a driving controller200, a gate driver300, and a data driver400. In an embodiment, the driving controller200and the data driver400may be integrated into one chip.

The display panel100has a display region AA on which an image is displayed and a peripheral region PA disposed adjacent to the display region AA. In an embodiment, the gate driver300may be mounted on the peripheral region PA of the display panel100.

The display panel100may include a plurality of gate lines GL, a plurality of data lines DL, and a plurality of pixels P electrically connected to the data lines DL and the gate lines GL. The gate lines GL may extend in a first direction D1and the data lines DL may extend in a second direction D2crossing the first direction D1.

The driving controller200may receive input image data IMG and an input control signal CONT from a host processor (e.g., a graphic processing unit; GPU). For example, the input image data IMG may include red image data, green image data and blue image data. In an embodiment, the input image data IMG may further include white image data. For another example, the input image data IMG may include magenta image data, yellow image data, and cyan image data. The input control signal CONT may include a master clock signal and a data enable signal. The input control signal CONT may further include a vertical synchronizing signal and a horizontal synchronizing signal.

The driving controller200may generate a first control signal CONT1, a second control signal CONT2, and output image data OIMG based on the input image data IMG and the input control signal CONT.

The driving controller200may generate the second control signal CONT2for controlling operation of the data driver400based on the input control signal CONT and output the second control signal CONT2to the data driver400. The second control signal CONT2may include a horizontal start signal and a load signal.

The driving controller200may receive the input image data IMG and the input control signal CONT, and generate the output image data OIMG. The driving controller200may output the output image data OIMG to the data driver400.

The gate driver300may generate gate signals for driving the gate lines GL in response to the first control signal CONT1input from the driving controller200. The gate driver300may output the gate signals to the gate lines GL. For example, the gate driver300may sequentially output the gate signals to the gate lines GL.

The data driver400may receive the second control signal CONT2and the output image data OIMG from the driving controller200. The data driver400may convert the output image data OIMG into data voltages having an analog type. The data driver400may output the data voltage to the data lines DL.

FIG.2is a conceptual diagram illustrating a driving frequency of the display panel100of the display device1000ofFIG.1.

Referring toFIGS.1and2, the display panel100may be driven with a variable driving frequency (i.e., operated in a variable frame mode). The first frame F1having the first driving frequency may include a first active period AC1and a first blank period BL1.

The second frame F2having a second driving frequency different from the first driving frequency may include a second active period AC2and a second blank period BL2. The third frame F3having a third driving frequency different from the first driving frequency and the second driving frequency may include a third active period AC3and a third blank period BL3.

The first active period AC1may have the same length as the second active period AC2, and the first blank period BL1may have a different length from the second active period BL2and the third active period.

The second active period AC2may have the same length as the third active period AC3, and the second blank period BL2may have a different length from the first active period and the third active period BL3.

A display device supporting the variable frame mode may include a data writing period in which the data voltages are written to the pixels P and a self-scan period in which only light emission is performed without writing the data voltages to the pixels P. The data writing period may be arranged in the active periods AC1, AC2, and AC3. The self-scan period may be arranged in the blank periods BL1, BL2, and BL3.

FIG.3is a diagram illustrating the display panel100of the display device1000ofFIG.1.

Referring toFIG.3, The display panel100may be divided into panel blocks PB. The panel blocks PB may include a reference panel block RPB, first panel blocks PB1, and second panel blocks PB2. The first panel blocks PB1may be disposed outside the reference panel block RPB in the display panel100. The second panel blocks PB2may be disposed outside the first panel blocks PB1in the display panel100. For example, the reference panel block RPB may be disposed in a center of the display panel100, the first panel blocks PB1may surround the reference panel block RPB, and the second panel blocks PB2may surround the first panel blocks PB1.

FIG.4is a flowchart illustrating a method of compensating for luminance of a display device according to embodiments of the present inventive concept,FIG.5is a conceptual diagram illustrating an example in which a position compensation value is determined according to the method ofFIG.4, andFIG.6is a conceptual diagram illustrating an example in which gamma curves GC1and GC2are generated according to the method ofFIG.4.

Referring toFIGS.1to6, the method ofFIG.4may include determining the position compensation value of each of the panel blocks PB for measurement grayscale values based on a difference between luminance of the reference panel block RPB and luminance of the each of panel blocks PB for a same grayscale value (S100), generating a first gamma curve GC1for a first driving frequency FR1based on luminance of the panel blocks PB for the measurement grayscale values at the first driving frequency FR1and the position compensation value of the each of panel blocks PB for the measurement grayscale values (S200), generating a second gamma curve GC2for a second driving frequency FR2different from the first driving frequency FR1based on a difference between luminance of the panel blocks PB for the measurement grayscale values at the second driving frequency FR2and the luminance of the panel blocks PB for the measurement grayscale values at the first driving frequency FR1(S300), and compensating for the input image data IMG based on the first gamma curve GC1and the second gamma curve GC2(S400). The measurement grayscale values may be grayscale values displayed on the panel blocks PB in measurement periods MP1, MP2, MP3, and MP4.

Specifically, the method ofFIG.4may include determining the position compensation value of each of the panel blocks PB for the measurement grayscale values based on the difference between luminance of the reference panel block RPB and luminance of the each of the panel blocks PB for the measurement grayscale values (S100).

For example, the method ofFIG.4may display the first measurement gray scale value G1to the panel blocks PB in a first measurement period MP1of the first driving frequency FR1, display the second measurement grayscale value G2to the panel blocks PB in a second measurement period MP2of the first driving frequency FR1, display the first measurement grayscale value G1to the reference panel block RPB and display grayscale values to the first panel blocks PB1and the second panel blocks PB2, in a third measurement period MP3of the first driving frequency FR1, and display the measurement grayscale values to the panel blocks PB in a same manner as in the third measurement period MP3, in a fourth measurement period MP4of the second driving frequency FR2.

A first position compensation value of each of the panel blocks PB for the first measurement grayscale value G1may be determined based on a difference between luminance of the reference panel block RPB for the first measurement grayscale value G1and luminance of the panel blocks PB for the first measurement grayscale value G1. A second position compensation value of each of the panel blocks PB for the second measurement grayscale value may be determined based on a difference between luminance of the reference panel block RPB for the second measurement grayscale value G2and luminance of the panel blocks PB for the second measurement grayscale value G2. The position compensation value of each of the panel blocks PB for other measurement grayscale values other than the first measurement grayscale value G1and the second measurement grayscale value G2among the measurement grayscale values may be determined based on the first position compensation value and the second position compensation value.

For example, it is assumed that the first measurement grayscale value G1is a 12 grayscale value and the second measurement grayscale value G2is a 4 grayscale value. The method ofFIG.4may measure luminance of all panel blocks PB on which the 12 grayscale value is displayed and luminance of all panel blocks PB on which 4 grayscale value is displayed through the first measurement period MP1and the second measurement period MP2. The first position compensation value of each of the panel blocks PB for the 12 grayscale value may be a difference between luminance of the reference panel block RPB on which the 12 grayscale value is displayed and luminance of all the panel blocks PB on which the 12 grayscale value is displayed. For example, when the luminance of the reference panel block RPB on which the 12 grayscale value is displayed is 2 nit and luminance of a specific panel block on which the 12 grayscale value is displayed is 1 nit, the position compensation value of the specific panel block for the 12 grayscale value may be 1 (2−1=1). For example, when the luminance of the reference panel block RPB on which a 4 grayscale value is displayed is 1 nit and luminance of a specific panel block on which the 4 grayscale value is displayed is 0.5 nit, the position compensation value of the specific panel block for the 4 grayscale value may be 0.5 (1−0.5=0.5). The position compensation value of each of the panel blocks PB for the first measurement grayscale value G1and the second measurement grayscale value G2may be determined by measuring luminance.

In an embodiment, the position compensation value of each of the panel blocks PB for the other measurement grayscale value may be determined by interpolating the position compensation value of each of the panel blocks PB for the first measurement grayscale value G1and the position compensation value of each of the panel blocks PB for the second measurement grayscale value G2. For example, when the first measurement grayscale value G1is the 12 grayscale value, the second measurement grayscale value G2is the 4 grayscale value, the position compensation value of a specific panel block for the 12 grayscale value is 1, and the position compensation value of the specific panel block for the 4 grayscale value is 0.5, the position compensation value of the specific panel block for a 8 grayscale value may be 0.75. Accordingly, the position compensation value of each of the panel blocks PB for all the measurement grayscale values may be determined.

In another embodiment, The position compensation value of each of the panel blocks PB for the other measurement grayscale values may be calculated using Equation 1.

LC=C×(G-G⁢2G⁢1-G⁢2)u×(LC⁢1-LC⁢2)+LC⁢2,[Equation⁢1]
where LC is the position compensation value of each of the panel blocks for the other measurement grayscale values, C is a first characteristic coefficient, G is the other measurement grayscale values, G1is the first measurement grayscale value, G2is the second measurement grayscale value, u is a second characteristic coefficient, LC1is the first position compensation value, and LC2is the second position compensation value. For example, when the first characteristic coefficient and the second characteristic coefficient are 1, the first measurement grayscale value G1is the 12 grayscale value, the second measurement grayscale value G2is the 4 grayscale value, the first position compensation value (the position compensation value of a specific panel block for the 12 grayscale value) is 1, and the second position compensation value (the position compensation value of the specific panel block for the 4 grayscale value) is 0.5, the position compensation value LC of the specific panel block for the 8 grayscale value may be 0.75. Accordingly, the position compensation value of each of the panel blocks PB for all the measurement grayscale values may be determined.

In an embodiment, the first characteristic coefficient C and the second characteristic coefficient u may be values calculated through artificial intelligence learning. For example, luminance may be measured while displaying various grayscale values on the panel blocks PB. The position compensation values for the other measurement grayscale values may be directly calculated through the measured luminance. The first characteristic coefficient C and the second characteristic coefficient u may be determined by repeatedly learning the artificial intelligence so that the directly calculated position compensation value is output as a result value.

Specifically, the method ofFIG.4may include generating the first gamma curve GC1for the first driving frequency FR1based on luminance of the panel blocks PB for the measurement grayscale values at the first driving frequency FR1and the position compensation value of each of the panel blocks PB for the measurement grayscale values (S200). For example, the first gamma curve GC1may be generated by adding the position compensation value of each of the panel blocks PB for the measurement grayscale values to luminance of the panel blocks PB for the measurement grayscale values measured in the third measurement period MP3.

For example, when luminance for a 11 grayscale value measured in the third measurement period MP3is 3 nit and the position compensation value of the panel block PB on which the 11 grayscale value is displayed in the third measurement period MP3is 1, luminance according to the 11 grayscale value (x-axis) may be 4 nit (y-axis) in the first gamma curve GC1. As shown inFIG.3, when the number of the panel blocks PB is 25, luminance according to 25 grayscale values is indicated on the first gamma curve GC1, and luminance according to the remaining grayscale values is measured by interpolation or the like. Accordingly, the first gamma curve GC1may be generated.

Specifically, the method ofFIG.4may include generating the second gamma curve GC2for the second driving frequency FR2different from the first driving frequency FR1based on the difference between the luminance of the panel blocks PB for the measurement grayscale values at the second driving frequency FR2and the luminance of the panel blocks PB for the measurement grayscale values at the first driving frequency FR1(S300). Accordingly, the second gamma curve GC2for the second driving frequency FR2may be generated.

For example, the second gamma curve GC2may be generated by adding the position compensation value of each of the panel blocks PB for the measurement grayscale values to the luminance of the panel blocks PB for the measurement grayscale values measured in the fourth measurement period MP4. The generating the second gamma curve GC2is substantially the same as the generating the first gamma curve GC1except that the second gamma curve GC2is generated through the luminance of the panel blocks PB for the measurement grayscale values at the second driving frequency FR2. Thus, any repetitive explanation will be omitted.

In another example, the second gamma curve GC2may be generated by changing the first gamma curve GC1by a difference between luminance of the panel blocks PB for the measurement grayscale values measured in the fourth measurement period MP4and luminance of the panel blocks PB for the measurement grayscale values measured in the third measurement period MP3.

Specifically, the method ofFIG.4may include compensating for the input image data IMG based on the first gamma curve GC1and the second gamma curve GC2(S400). Gamma curves for frequencies other than the first driving frequency FR1and the second driving frequency FR2may be generated based on the first gamma curve GC1and the second gamma curve GC2. For example, the gamma curves for the frequencies other than the first driving frequency FR1and the second driving frequency FR2may be generated by interpolating the first gamma curve GC1and the second gamma curve GC2.

The input image data IMG may be compensated for by a difference between the first gamma curve GC1and gamma curves other than the first gamma curve GC1. That is, the first gamma curve GC1may be a reference gamma curve. In other words, the input image data IMG may be compensated so that a correlation between grayscale values and luminance at driving frequencies different from the first driving frequency FR1becomes the same as that of the first gamma curve GC1. Accordingly, by compensating the input image data IMG according to the driving frequency, a difference in luminance according to the driving frequency may be compensated.

In an embodiment, the first driving frequency FR1may be greater than the second driving frequency FR2. Accordingly, the second gamma curve GC2may indicate lower luminance than the first gamma curve GC1at the same grayscale value.

FIG.7is a conceptual diagram illustrating an example in which the position compensation value is determined according to a method of compensating for luminance of a display device according to embodiments of the present inventive concept.

The method according to the present embodiment is substantially the same as the method ofFIG.4except for determining the position compensation value. Thus, the same reference numerals are used to refer to the same or similar element, and any repetitive explanation will be omitted.

Referring toFIGS.1to3,6, and7, the method ofFIG.7may include determining a position compensation value of each of the panel blocks PB for the measurement grayscale values based on the difference between luminance of the reference panel block RPB and luminance of the panel blocks PB for a same grayscale value.

For example, the method ofFIG.7may display the third measurement gray scale value G3to the reference panel block RPB, the first measurement grayscale value G1to the first panel blocks PB1, and the third measurement grayscale value to the second panel blocks PB2in the first measurement period MP1of the first driving frequency FR1, display the second measurement grayscale value G2to the reference panel blocks RPB and the first panel blocks PB1, and the first measurement grayscale value G1to the second panel blocks PB2in the second measurement period MP2of the first driving frequency FR1, and display the first measurement grayscale value G1to the reference panel block RPB, and the different measurement grayscale values to the first panel blocks PB1and the second panel blocks PB2in the third measurement period MP3of the first driving frequency FR1. In an embodiment, the first measurement grayscale value G1may be greater than the second measurement grayscale value G2and may be smaller than the third measurement grayscale value G3.

A third position compensation value of each of the first panel blocks PB1for the first measurement grayscale value G1may be determined based on a difference between luminance of the reference panel block RPB for the first measurement grayscale value and luminance of the first panel blocks PB1for the first measurement grayscale value. A fourth position compensation value of each of the second panel blocks PB2for the first measurement grayscale value G1may be determined based on a difference between the luminance of the reference panel block RPB for the first measurement grayscale value G1and luminance of the second panel blocks PB2for the first measurement grayscale value G1. A fifth position compensation value of each of the first panel blocks PB1for the second measurement grayscale value G2may be determined based on a difference between luminance of the reference panel block RPB for the second measurement grayscale value G2and luminance of the first panel blocks PB1for the second measurement grayscale value G2. A sixth position compensation value of each of the second panel blocks PB2for the third measurement grayscale value G3may be determined based on a difference between luminance of the reference panel block RPB for the third measurement grayscale value G3and luminance of the second panel blocks PB2for the third measurement grayscale value G3. A position compensation value of each of the first panel blocks PB1for first other measurement grayscale values other than the first measurement grayscale value G1and the second measurement grayscale value G2among the measurement grayscale values may be determined based on the third position compensation value and the fifth position compensation value. A position compensation value of each of the second panel blocks PB2for second other measurement grayscale values other than the first measurement grayscale value G1and the third measurement grayscale value G3among the measurement grayscale values may be determined based on the fourth position compensation value and the sixth position compensation value.

For example, it is assumed that the first measurement grayscale value G1is the 12 grayscale value, the second measurement grayscale value G2is the 4 grayscale value, and the third measurement grayscale value G3is a 40 grayscale value. The method ofFIG.7may measure luminance of all panel blocks PB on which the 12 grayscale value is displayed, luminance of all panel blocks PB on which 4 grayscale value is displayed, and luminance of all panel blocks PB on which the 40 grayscale value is displayed through the first measurement period MP1, the second measurement period MP2, and the third measurement period MP3. The first position compensation value of each of the panel blocks PB for the 12 grayscale value may be a difference between luminance of the reference panel block RPB on which the 12 grayscale value is displayed and luminance of each of the panel blocks PB on which the 12 grayscale value is displayed. For example, when the luminance of the reference panel block RPB on which the 12 grayscale value is displayed is 2 nit and luminance of a specific panel block on which the 12 grayscale value is displayed is 1 nit, the position compensation value of the specific panel block for the 12 grayscale value may be 1 (2−1=1). For example, when the luminance of the reference panel block RPB on which a 4 grayscale value is displayed is 1 nit and luminance of a specific panel block on which the 4 grayscale value is displayed is 0.5 nit, the position compensation value of the specific panel block for the 4 grayscale value may be 0.5 (1−0.5=0.5). For example, when the luminance of the reference panel block RPB on which a 40 grayscale value is displayed is 4 nit and luminance of a specific panel block on which the 40 grayscale value is displayed is 2.5 nit, the position compensation value of the specific panel block for the 40 gray scale value may be 1.5 (4−2.5=1.5). The position compensation value of each of the panel blocks PB for the first measurement grayscale value G1, the second measurement grayscale value G2, and the third measurement grayscale value G3may be determined by measuring luminance.

In an embodiment, the position compensation value of each of the first panel blocks PB1for the first other measurement grayscale values may be determined based on the third position compensation value (i.e., the position compensation value of each of the first panel blocks PB1for the first measurement grayscale value G1) and the fifth position compensation value (i.e., the position compensation value of each of the first panel blocks PB1for the second measurement grayscale value G2). Accordingly, a position compensation value of each of the first panel blocks PB1for all grayscale values may be determined.

In another embodiment, the position compensation value of each of the first panel blocks PB1for the first other measurement grayscale values may be determined by using Equation 2.

LCA=C×(G-G⁢2G⁢1-G⁢2)u×(LC⁢3-LC⁢5)+LC⁢5,[Equation⁢2]
where LCA is the position compensation value of each of the first panel blocks PB1for the first other measurement grayscale values, C is the first characteristic coefficient, G is the first other measurement grayscale values, G1is the first measurement grayscale value, G2is the second measurement grayscale, u is the second characteristic coefficient, LC3is the third position compensation value, and LC5is the fifth position compensation value. For example, when the first characteristic coefficient and the second characteristic coefficient are 1, the first measurement grayscale value G1is the 12 grayscale value, the second measurement grayscale value G2is the 4 grayscale value, the third position compensation value of a specific first panel block is 1, and the fifth position compensation value of the specific first panel block is 0.5, the position compensation value of the specific first panel block for the 8 grayscale value may be 0.75. Accordingly, a position compensation value of each of the first panel blocks PB1for all grayscale values may be determined.

In an embodiment, the first characteristic coefficient C and the second characteristic coefficient u may be values calculated through artificial intelligence learning. For example, luminance may be measured while displaying various grayscale values on the panel blocks PB. The position compensation values for the first other measurement grayscale values may be directly calculated through the measured luminance. The first characteristic coefficient C and the second characteristic coefficient u may be determined by repeatedly learning the artificial intelligence so that the directly calculated position compensation value is output as a result value.

In an embodiment, the position compensation value of each of the second panel blocks PB2for the second other measurement grayscale values may be determined based on the fourth position compensation value (i.e., the position compensation value of each of the second panel blocks PB2for the first measurement grayscale value G1) and the sixth position compensation value (i.e., the position compensation value of each of the second panel blocks PB2for the third measurement grayscale value G3). For example, when the first measurement grayscale value G1is the 12 grayscale value, the third measurement grayscale value G3is the 40 grayscale value, the fourth position compensation value of a specific first panel block is 0.5, and the sixth position compensation value of the specific first panel block is 1, the position compensation value of the specific first panel block for a 26 grayscale value may be 0.75. Accordingly, a position compensation value of each of the second panel blocks PB2for all grayscale values may be determined.

In another embodiment, the position compensation value of each of the second panel blocks PB2for the second other measurement grayscale values may be determined by using Equation 3.

LCB=C×(G-G⁢1G⁢3-G⁢1)u×(LC⁢5-LC⁢4)+LC⁢4,[Equation⁢3]
where LCB is the position compensation value of each of the second panel blocks PB2for the second other measurement grayscale values, C is the first characteristic coefficient, G is the second other measurement grayscale values, G1is the first measurement grayscale value, G3is the third measurement grayscale value, u is the second characteristic coefficient, LC6is the sixth position compensation value, and LC4is the fourth position compensation value. For example, when the first characteristic coefficient C and the second characteristic coefficient u are 1, the first measurement grayscale value G1is the 12 grayscale value, the third measurement grayscale value G3is the 40 grayscale value, the fourth position compensation value of a specific second panel block is 0.5, and the sixth position compensation value of the specific second panel block is 1, the position compensation value of the specific second panel block for the 26 grayscale value may be 0.75. Accordingly, a position compensation value of each of the second panel blocks PB2for all grayscale values may be determined.

In an embodiment, the first characteristic coefficient C and the second characteristic coefficient u may be values calculated through artificial intelligence learning. For example, luminance may be measured while displaying various grayscale values on the panel blocks PB. The position compensation values for the second other measurement grayscale values may be directly calculated through the measured luminance. The first characteristic coefficient C and the second characteristic coefficient u may be determined by repeatedly learning the artificial intelligence so that the directly calculated position compensation value is output as a result value.

In an embodiment, the measurement grayscale values displayed on the first panel blocks PB1may be smaller than the measurement grayscale values displayed on the second panel blocks PB2in the third measurement period MP3. The first measurement grayscale value G1may be greater than the second measurement grayscale value G2and may be smaller than the third measurement grayscale value G3. Accordingly, the position compensation value of each of the first panel blocks PB1on which grayscale values smaller than grayscale values displayed on the second panel blocks PB2are displayed may be determined based on the position compensation value for the first measurement value G1and the second measurement value G2smaller than the third measurement value G3, and the position compensation value of each of the second panel blocks PB2may be determined based on the position compensation value for the second measurement value G2and the third measurement value G3.

FIG.8is a flowchart illustrating a method of compensating for luminance of a display device according to embodiments of the present inventive concept, andFIG.9is a conceptual diagram illustrating an example in which gamma curves GC1, GC2, and GC3are generated according to the method ofFIG.8.

The method according to the present embodiment is substantially the same as the method ofFIG.7except for generating the gamma curves GC1, GC2, and GC3. Thus, the same reference numerals are used to refer to the same or similar element, and any repetitive explanation will be omitted.

Referring toFIGS.1to3,8, and9, the method ofFIG.8may include determining the position compensation value of each of the panel blocks PB for measurement grayscale values based on a difference between luminance of the reference panel block RPB and luminance of the each of the panel blocks PB for a same grayscale value (S100), generating a first gamma curve GC1for a first driving frequency FR1based on the luminance of the panel blocks PB for the measurement grayscale values at the first driving frequency FR1and the position compensation value of each of the panel blocks PB for the measurement grayscale values (S200), generating a second gamma curve GC2for a second driving frequency FR2different from the first driving frequency FR1based on a difference between luminance of the panel blocks PB for the measurement grayscale values at the second driving frequency FR2and the luminance of the panel blocks PB for the measurement grayscale values at the first driving frequency FR1(S300), generating a third gamma curve GC3for a third driving frequency FR3different from the first driving frequency FR1and the second driving frequency FR2based on a difference between luminance of the panel blocks PB for the measurement grayscale values at the third driving frequency FR3and the luminance of the panel blocks PB for the measurement grayscale values at the first driving frequency FR1(S500), and compensating for the input image data IMG based on the first gamma curve GC1, the second gamma curve GC2, and the third gamma curve GC3(S600).

For example, the method ofFIG.8may display the first measurement gray scale value G1to the panel blocks PB in the first measurement period MP1of the first driving frequency FR1, display the second measurement grayscale value G2to the panel blocks PB in the second measurement period MP2of the first driving frequency FR1, display the first measurement grayscale value G1to the reference panel block RPB and the different measurement grayscale values to the first panel blocks PB1and the second panel blocks PB2in the third measurement period MP3of the first driving frequency FR1, display the measurement grayscale values to the panel blocks PB in a same manner as in the third measurement period MP3in the fourth measurement period MP4of the second driving frequency FR2, and display the measurement grayscale values to the panel blocks PB in a same manner as in the third measurement period MP3in a fifth measurement period MP5of the third driving frequency FR3.

Specifically, the method ofFIG.8may include generating the first gamma curve GC1for the first driving frequency FR1based on luminance of the panel blocks PB for the measurement grayscale values at the first driving frequency FR1and the position compensation value of each of the panel blocks PB for the measurement grayscale values (S200). For example, the first gamma curve GC1may be generated by adding the position compensation value of each of the panel blocks PB for the measurement grayscale values to luminance of the panel blocks PB for the measurement grayscale values measured in the third measurement period MP3.

For example, when luminance for the 11 grayscale value measured in the third measurement period MP3is 3 nit and the position compensation value of the panel block PB on which the 11 grayscale value is displayed in the third measurement period MP3is 1, luminance according to the 11 grayscale value (x-axis) may be 4 nit (y-axis) in the first gamma curve GC1. As shown inFIG.3, when the number of the panel blocks PB is 25, luminance according to 25 grayscale values is indicated on the first gamma curve GC1, and luminance according to the remaining grayscale values is measured by interpolation or the like. Accordingly, the first gamma curve GC1may be generated.

Specifically, the method ofFIG.8may include generating the second gamma curve GC2for the second driving frequency FR2different from the first driving frequency FR1based on the difference between the luminance of the panel blocks PB for the measurement grayscale values at the second driving frequency FR2and the luminance of the panel blocks PB for the measurement grayscale values at the first driving frequency FR1(S300). Accordingly, the second gamma curve GC2for the second driving frequency FR2may be generated.

For example, the second gamma curve GC2may be generated by adding the position compensation value of each of the panel blocks PB for the measurement grayscale values to the luminance of the panel blocks PB for the measurement grayscale values measured in the fourth measurement period MP4. The generating the second gamma curve GC2is substantially the same as the generating the first gamma curve GC1except that the second gamma curve GC2is generated through the luminance of the panel blocks PB for the measurement grayscale values at the second driving frequency FR2. Thus, any repetitive explanation will be omitted.

In another example, the second gamma curve GC2may be generated by changing the first gamma curve GC1by a difference between luminance of the panel blocks PB for the measurement grayscale values measured in the fourth measurement period MP4and luminance of the panel blocks PB for the measurement grayscale values measured in the third measurement period MP3.

Specifically, the method ofFIG.8may include generating the third gamma curve GC3for the third driving frequency FR3different from the first driving frequency FR1and the second driving frequency FR2based on a difference between luminance of the panel blocks PB for the measurement grayscale values at the third driving frequency FR3and the luminance of the panel blocks PB for the measurement grayscale values at the first driving frequency FR1(S500). Accordingly, the third gamma curve GC3for the second driving frequency FR2may be generated.

For example, the third gamma curve GC3may be generated by adding the position compensation value of each of the panel blocks PB for the measurement grayscale values to the luminance of the panel blocks PB for the measurement grayscale values measured in the fifth measurement period MP5. The generating the third gamma curve GC3is substantially the same as the generating the first gamma curve GC1except that the third gamma curve GC3is generated through the luminance of the panel blocks PB for the measurement grayscale values at the third driving frequency FR3. Thus, any repetitive explanation will be omitted.

In another example, the third gamma curve GC3may be generated by changing the first gamma curve GC1by a difference between luminance of the panel blocks PB for the measurement grayscale values measured in the fifth measurement period MP5and luminance of the panel blocks PB for the measurement grayscale values measured in the third measurement period MP3.

Specifically, the method ofFIG.8may include compensating for the input image data IMG based on the first gamma curve GC1, the second gamma curve GC2, and the third gamma curve GC3(S600). Gamma curves for frequencies other than the first driving frequency FR1, the second driving frequency FR2, and the third driving frequency FR3may be generated based on the first gamma curve GC1, the second gamma curve GC2, and the third gamma curve GC3. For example, the gamma curves for the frequencies other than the first driving frequency FR1, the second driving frequency FR2, and the third driving frequency FR3may be generated by interpolating the first gamma curve GC1, the second gamma curve GC2, and the third gamma curve GC3. The method ofFIG.8may generate the gamma curves other than the first driving frequency FR1, the second driving frequency FR2, and the third driving frequency FR3based on the gamma curves GC1, GC2, and GC3for the first driving frequency FR1, the second driving frequency FR2, and the third driving frequency FR3, but the method is not limited thereto. For example, the method ofFIG.8may generate gamma curves for different frequencies based on gamma curves for four or more driving frequencies.

The input image data IMG may be compensated for by a difference between the first gamma curve GC1and gamma curves other than the first gamma curve GC1. That is, the first gamma curve GC1may be a reference gamma curve. In other words, the input image data IMG may be compensated so that a correlation between grayscale values and luminance at driving frequencies different from the first driving frequency FR1becomes the same as that of the first gamma curve GC1. Accordingly, by compensating the input image data IMG according to the driving frequency, a difference in luminance according to the driving frequency may be compensated.

In an embodiment, the first driving frequency FR1may be greater than the second driving frequency FR2and the third driving frequency FR3. Accordingly, the second gamma curve GC2and the third gamma curve GC3may indicate lower luminance than the first gamma curve GC1at the same grayscale value.

The inventive concepts may be applied to any electronic device including the display device. For example, the inventive concepts may be applied to a television (TV), a digital TV, a 3D TV, a mobile phone, a smart phone, a tablet computer, a virtual reality (VR) device, a wearable electronic device, a personal computer (PC), a home appliance, a laptop computer, a personal digital assistant (PDA), a portable multimedia player (PMP), a digital camera, a music player, a portable game console, a navigation device, etc.