Display device

Abstract

The display device includes a display panel having a plurality of pixels. The interpolation unit generates a first voltage value corresponding to the input data value by using a set gamma lookup table. The gamma correction unit selects at least one dimming lookup table from among a set of multiple dimming lookup tables based on the dimming value, and corrects the first voltage value based on the at least one dimming lookup table to calculate a first output data value. The gamma voltage generation unit generates a plurality of gamma voltages having a linear relationship. The data driving unit selects a first gamma voltage from among the plurality of gamma voltages based on the first output data value, and provides the first gamma voltage as a data voltage to the display panel.

Description

Technical Field

[0001] Embodiments of the present invention relate to a display device. Background Art

[0002] A display device includes a display panel and a driving unit. The display panel includes scan lines, data lines, and pixels. The driving unit includes a scan driving unit that sequentially provides scan signals to the scan lines and a data driving unit that provides data signals to the data lines. Each pixel can emit light with a brightness corresponding to the data signal provided through the corresponding data line in response to the scan signal provided through the corresponding scan line.

[0003] The data driving unit can generate gamma voltages corresponding to multiple gray levels and use the gamma voltages to transform the gray level values of image data into data signals.

[0004] Due to hardware size limitations, the data driving unit only generates reference gamma voltages corresponding to a part of each gamma voltage (i.e., reference gamma voltages corresponding to part of the tab points), and divides the reference gamma voltages to generate gamma voltages.

[0005] However, since the gamma voltages are linearly interpolated between the reference gamma voltages, the image displayed using the gamma voltages has a brightness error based on an ideal gamma curve (e.g., a 2.2 gamma curve).

[0006] In addition, when the display device is driven in a data dimming driving mode, the maximum brightness of the display device decreases, and the load is only concentrated on the gamma voltages in a partial interval of the reference gamma voltages (e.g., gamma voltages corresponding to a low gray level interval), so the brightness error may be more apparent. Summary of the Invention

[0007] An object of the present invention is to provide a display device capable of reducing brightness error.

[0008] To achieve an object of the present invention, a display device according to embodiments of the present invention includes: a display panel including a plurality of pixels; a power supply unit supplying a first power supply voltage and a second power supply voltage required for driving each of the pixels; a brightness correction unit generating a first data correction value corresponding to a voltage level of the second power supply voltage, multiplying a first input data value and the first data correction value to output a first corrected data value; an interpolation unit calculating a first voltage value corresponding to the first corrected data value by using a set gamma look-up table; a first gamma correction unit calculating a first voltage correction value corresponding to the voltage level of the second power supply voltage, adding the first voltage value and the first voltage correction value to calculate a first output data value; a gamma voltage generation unit generating a plurality of gamma voltages having a linear relationship; and a data driving unit selecting a first gamma voltage from the plurality of gamma voltages based on the first output data value, and providing the first gamma voltage as a data voltage to the display panel.

[0009] According to an embodiment, the first data correction value may be represented by P bits (where P is a natural number), the first input data value may be represented by Q bits (where Q is a natural number), and the first corrected data value may be represented by P+Q-1 bits.

[0010] According to an embodiment, the interpolation unit may determine a first voltage value range based on the upper R bits (where R is a natural number less than P) of the first corrected data value, and interpolate the first voltage value range based on the remaining lower bits of the first corrected data value to generate the first voltage value.

[0011] According to an embodiment, the gamma look-up table may include first gamma data, and the first gamma data may include a minimum voltage value of the first voltage value range and a triangular voltage value, where the triangular voltage value is a difference between a maximum voltage value and the minimum voltage value of the first voltage value range.

[0012] According to an embodiment, the interpolation unit may interpolate the triangular voltage value of the first gamma data based on the remaining bits in the first corrected data value.

[0013] According to an embodiment, the display device may further include: a second gamma correction unit selecting at least one dimming look-up table from a set of dimming look-up tables based on a dimming value, and correcting the first output data value based on the at least one dimming look-up table to output a first corrected voltage value, and the data driving unit receiving the first corrected voltage value as the first output data value.

[0014] According to an embodiment, it may be that each of the plurality of dimming look-up tables includes gamma correction values set corresponding to respective representative gray values, and the second gamma correction unit selects a first dimming look-up table and a second dimming look-up table based on the dimming value, and interpolates the gamma correction values in the first dimming look-up table and the gamma correction values in the second dimming look-up table based on the dimming value to generate an interpolated look-up table, and uses the interpolated look-up table to correct the corrected voltage value.

[0015] According to an embodiment, it may be that the number of the representative gray values is more than twice the number of reference marks included in the gamma voltage generation unit.

[0016] According to an embodiment, it may be that the second gamma correction unit interpolates the correction values in the interpolated look-up table to generate a gamma correction value for the first corrected voltage value, and performs an addition operation on the first corrected voltage value and the gamma correction value.

[0017] According to an embodiment, it may be that each of the plurality of dimming look-up tables further includes an offset set for a first representative gray value among the plurality of representative gray values, and based on the first representative gray value, it is set such that as the gray value increases, the offset is proportional to the square root of the gray value, and as the gray value decreases, the offset is proportional to the gray value.

[0018] According to an embodiment, it may be that the plurality of gamma voltages have a first-order linear relationship with respect to the first output data value.

[0019] According to an embodiment, it may be that the first input data value and the first output data value are located on a gray-scale - voltage curve, the differential value of the gray-scale - voltage curve has a constant value in a first interval and is expressed as a first-order equation in a second interval, and the input data value corresponding to the first interval is greater than the input data value corresponding to the second interval.

[0020] According to an embodiment, it may be that the differential value is expressed as a second-order equation in a third interval, and the input data value corresponding to the third interval is less than the input data value corresponding to the second interval.

[0021] According to an embodiment, it may be that a reference differential value with respect to a representative gray value is determined during an optical compensation process for setting a data voltage with respect to the representative gray value, and the constant value and the first-order equation are set based on the differential value.

[0022] To achieve an object of the present invention, a display device according to embodiments of the present invention includes: a display panel including a plurality of pixels; an interpolation unit configured to generate a first voltage value corresponding to an input data value by using a set gamma lookup table; a gamma correction unit configured to select at least one dimming lookup table from a plurality of set dimming lookup tables based on a dimming value, and correct the first voltage value based on the at least one dimming lookup table to calculate a first output data value; a gamma voltage generation unit configured to generate a plurality of gamma voltages having a linear relationship; and a data driving unit configured to select a first gamma voltage from the plurality of gamma voltages based on the first output data value, and provide the first gamma voltage as a data voltage to the display panel.

[0023] According to an embodiment, it may be that the plurality of dimming lookup tables each include a plurality of gamma correction values set corresponding to respective representative gray values, the gamma correction unit selects a first dimming lookup table and a second dimming lookup table from the plurality of dimming lookup tables based on the dimming value, and interpolates the plurality of gamma correction values in the first dimming lookup table and the plurality of gamma correction values in the second dimming lookup table based on the dimming value to generate an interpolated lookup table, and corrects the corrected voltage value by using the interpolated lookup table.

[0024] According to an embodiment, it may be that the gamma correction unit interpolates the plurality of correction values in the interpolated lookup table to generate a gamma correction value for the first voltage value, and performs an addition operation on the first voltage value and the gamma correction value.

[0025] According to an embodiment, it may be that the interpolation unit determines a first voltage value range based on the upper R bits (where R is a natural number less than P) in the input data value, and interpolates the first voltage value range based on the remaining bits in the input data value to generate the first voltage value.

[0026] According to an embodiment, it may be that the gamma lookup table includes first gamma data, the first gamma data includes a minimum voltage value of the first voltage value range and a triangular voltage value, and the triangular voltage value is the difference between the maximum voltage value and the minimum voltage value of the first voltage value range.

[0027] According to an embodiment, it may be that the interpolation unit interpolates the triangular voltage value of the first gamma data based on the remaining bits in the input data value.

[0028] (Advantages of the Invention)

[0029] Embodiments of the present invention relate to a display device that uses a set gamma lookup table to transform an input gray value into a data value based on a 2.2 gamma curve, thereby outputting a gamma voltage that more closely conforms to an ideal gamma curve. Therefore, the luminance error can be reduced.

[0030] In addition, the display device uses a dimming lookup table including a plurality of correction values for more tabulation points to additionally compensate the data value, so that the luminance error can also be reduced during the dimming driving of the display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a block diagram showing a display device according to embodiments of the present invention.

[0032] Figure 2 is a diagram showing Figure 1 an example of a data conversion unit included in the display device.

[0033] Figure 3 is a diagram showing the relationship between an input gray value and a voltage value provided to an interpolation unit included in the Figure 2 data conversion unit.

[0034] Figure 4 is a diagram for explaining Figure 2 the operation of the interpolation unit included in the data conversion unit.

[0035] Figure 5 is a diagram showing an example of a dimming lookup table used in a second gamma correction unit included in the Figure 2 data conversion unit.

[0036] Figure 6 is a diagram for explaining Figure 2 the operation of the second gamma correction unit included in the data conversion unit.

[0037] Figure 7 is a chart showing a comparison example of luminance curves corresponding to each gray level of a display device showing Figure 1 the display device.

[0038] Figure 8 is a chart showing an example of a luminance curve of a Figure 1 display device.

[0039] Figure 9 is a chart showing an example of a plurality of gamma voltages generated by a gamma voltage generation unit included in a Figure 1 display device.

[0040] Figure 10 is a chart showing the relationship between an input gray value and a voltage value obtained through optical compensation of a Figure 1 display device.

[0041] Figure 11 is a diagram obtained by differentiating the diagram of Figure 10 .

[0042] Figure 12 represents a process of adding and correcting the diagram of Figure 10 .

[0043] Figure 13 represents a diagram showing the offset of the dimming lookup table used in the second gamma correction unit included in the display device of Figure 1 .

[0044] Figure 14 represents a diagram showing the change in the luminance curve with respect to the offset set in Figure 13 .

[0045] Figure 15 represents Figure 1 an example of a pixel included in the display device of DETAILED DESCRIPTION OF THE INVENTION

[0046] The present invention can have various modifications and can be implemented in various ways. Specific embodiments are illustrated in the drawings and will be described in detail herein. However, the present invention is not limited to the embodiments disclosed below and can be implemented in various ways.

[0047] On the other hand, in the drawings, some constituent elements that are not directly related to the features of the present invention may be omitted in order to clearly show the present invention. In addition, the sizes or ratios of some constituent elements on the drawings may be exaggerated. In all the drawings, the same or similar constituent elements are given the same reference numerals as much as possible even if they are shown in other drawings, and repeated descriptions are omitted.

[0048] Figure 1 is a block diagram showing the display device according to embodiments of the present invention.

[0049] Referring to Figure 1 , the display device 100 may include a display unit 110 (or a display panel), a scan driving unit 120 (or a scan driving circuit), a driving unit 130, a memory 140 (or a storage unit), a light emitting driving unit 150 (or a light emitting driving circuit), and a power supply unit 160.

[0050] The display unit 110 may include scan lines SL1 to SLn (where n is a positive integer), data lines DL1 to DLm (where m is a positive integer), light emission control lines EL1 to ELn, and pixels PXL. The pixels PXL may be arranged in a region (e.g., a pixel region) defined by the scan lines SL1 to SLn, the data lines DL1 to DLm, and the light emission control lines EL1 to ELn.

[0051] The pixel PXL can be connected to at least one of the scan lines SL1 to SLn, one of the data lines DL1 to DLm, and one of the emission control lines EL1 to ELn. For example, the pixel PXL can be connected to the scan line SLi, the previous scan line SLi-1 adjacent to the scan line SLi, the data line DLj, and the emission control line ELi (where i and j are positive integers respectively).

[0052] The pixel PXL can be initialized in response to a scan signal provided through the previous scan line SLi-1 (or a scan signal provided at the previous moment), store or record a data signal (or a data voltage) provided through the data line DLj in response to a scan signal provided through the scan line SLi (or a scan signal provided at the current moment), and emit light with a brightness corresponding to the stored data signal in response to an emission control signal provided through the emission control line ELi. Regarding the pixel PXL, it will be described with reference to Figure 15 described later.

[0053] The scan driving unit 120 can generate a scan signal based on a scan control signal SCS and sequentially provide the scan signal to the scan lines SL1 to SLn. Here, the scan control signal SCS can include a start signal (or a start pulse), a clock signal, etc., and the scan control signal SCS can be provided from the driving unit 130. For example, the scan driving unit 120 can include: a shift register (or a driving stage), which sequentially generates and outputs a scan signal corresponding to a start signal in the form of a pulse by using a clock signal.

[0054] The scan driving unit 120 can be formed in the display unit 110 through the same process as the process of forming the pixel PXL, or can be separately implemented by an integrated circuit.

[0055] The emission driving unit 150 can generate an emission control signal based on an emission driving control signal ECS and sequentially or simultaneously provide the emission control signal to the emission control lines EL1 to ELn. Here, the emission driving control signal ECS can include an emission start signal, an emission clock signal, etc., and the emission driving control signal ECS can be provided from the driving unit 130. For example, the emission driving unit 150 can include: a shift register, which sequentially generates and outputs an emission control signal corresponding to an emission start signal in the form of a pulse by using an emission clock signal.

[0056] The driving unit 130 can generate a data signal based on input image data DATA1 and a control signal CS provided from the outside (e.g., a graphics processor).

[0057] The driving unit 130 may include a control unit 131 (or a timing control unit), a data conversion unit 132, a gamma voltage generation unit 133, and a data driving unit 134. The control unit 131, the data conversion unit 132, the gamma voltage generation unit 133, and the data driving unit 134 may be implemented by one integrated circuit and may be mounted on a flexible circuit board connected to the display unit 110. However, this is only an example and is not limited thereto. For example, the control unit 131 may include the data conversion unit 132 and be implemented by one integrated circuit, and the data driving unit 134 may be implemented by an integrated circuit independent of the control unit 131.

[0058] The control unit 131 may receive input image data DATA1 and a control signal CS from the outside, generate a scan control signal SCS and a data control signal DCS based on the control signal CS, and transform the input image data DATA1 to generate image data DATA2. Here, the control signal CS may include a vertical synchronization signal, a horizontal synchronization signal, a clock signal, etc. For example, the control unit 131 may transform the input image data DATA1 in RGB format into image data DATA2 in RGBG format that conforms to the pixel arrangement in the display unit 110.

[0059] The data conversion unit 132 may use a lookup table LUT (or a gamma lookup table) to transform the input gray value included in the image data DATA2 into a voltage value VDATA (or a data value within a voltage range). Here, the lookup table LUT may include the voltage value VDATA corresponding to the input gray value, and the lookup table LUT may be provided to the data conversion unit 132 from the memory 140. The voltage value VDATA includes information (e.g., selection information) about one of the plurality of gamma voltages V_GAMMA generated by the gamma voltage generation unit 133, and the relationship between the input gray value and the voltage value VDATA may correspond to or be consistent with a 2.2 gamma curve. Regarding the voltage value VDATA, it will be referred to Figure 3 and Figure 4 described later.

[0060] In one embodiment, the data conversion unit 132 may change the input gray value based on the power supply voltage information I_VSS. Here, the power supply voltage information I_VSS represents the voltage level of the power supply voltage (for example, the second power supply voltage VSS) supplied to the display unit 110, and the power supply voltage information I_VSS may be provided from the power supply unit 160. In addition, in order to reduce power consumption, the display device 100 may be such that the lower the target brightness (or target brightness level) of the image displayed by the display device 100, the smaller the magnitude of the second power supply voltage VSS, and the display device 100 may vary the input gray value corresponding to the change in the target brightness and the change in the second power supply voltage VSS. For example, the data conversion unit 132 may reduce the input gray value based on the power supply voltage information I_VSS to generate a corrected data value (or corrected gray value). In this case, the data conversion unit 132 may use a look-up table LUT to convert the corrected data value into a voltage value VDATA.

[0061] In one embodiment, the data conversion unit 132 may compensate the voltage value VDATA based on the dimming value I_DIM (or dimming information). Here, the dimming value I_DIM may represent the target brightness level of the display device 100. The dimming value I_DIM may be provided from the control unit 131.

[0062] In addition, according to the dimming value I_DIM, the maximum brightness of the display device 100 (or the image displayed by the display device 100) may decrease, and thus, the brightness error (or brightness error ratio) may become relatively larger. Therefore, the data conversion unit 132 may correct the voltage value VDATA using a look-up table LUT (or dimming look-up table) when the dimming value I_DIM is below the reference dimming value (for example, when the maximum brightness of the display device 100 is below 100 nits (nit)).

[0063] The gamma voltage generation unit 133 may generate a plurality of gamma voltages V_GAMMA that have a linear relationship with each other. For example, the gamma voltage generation unit 133 may be configured to include a resistor string and a gamma buffer that transfers a reference gamma voltage to a tab (or tab point) of the resistor string. Since the gamma voltage generation unit 133 may be implemented by a general analog gamma integrated circuit, the detailed configuration of the gamma voltage generation unit 133 is omitted.

[0064] The data driving unit 134 can generate a data signal based on the data control signal DCS provided from the control unit 131, the voltage value VDATA provided from the data conversion unit 132, and the plurality of gamma voltages V_GAMMA provided from the gamma voltage generation unit 133, and provide the data signal to the display unit 110 (or the pixel PXL). Here, the data control signal DCS is a signal for controlling the operation of the data driving unit 134, and may include a load signal (or a data strobe signal) indicating the output of a valid data signal, etc.

[0065] For example, the data driving unit 134 may be configured to include a shift register, a latch, a decoder, an output buffer, etc. The data driving unit 134 can sequentially provide the voltage value VDATA to the shift register and the latch or temporarily store it in the shift register and the latch based on the data control signal DCS, select a gamma voltage corresponding to the voltage value VDATA among the plurality of gamma voltages V_GAMMA through the decoder, and output the selected gamma voltage as a data signal (or a data voltage) to the data line through the output buffer.

[0066] The memory 140 can store a look-up table LUT. For example, the memory 140 can be implemented by a flash memory, installed on a flexible circuit board on which the driving unit 130 is installed, and can be connected to the driving unit 130 (e.g., the data conversion unit 132).

[0067] In one embodiment, the look-up table LUT may include a gamma look-up table and a dimming look-up table. Regarding the gamma look-up table and the dimming look-up table, reference will be made to Figures 3 to 5 described later.

[0068] The power supply unit 160 can supply a first power supply voltage VDD and a second power supply voltage VSS to the display unit 110. Here, the first power supply voltage VDD and the second power supply voltage VSS are voltages required for the operation of the pixel PXL, and the first power supply voltage VDD may have a voltage level higher than that of the second power supply voltage VSS. In addition, an initialization power supply voltage Vint can also be provided to the display unit 110. The first power supply voltage VDD, the second power supply voltage VSS, and the initialization power supply voltage Vint can be provided to the display unit 110 from a separately provided power supply unit.

[0069] In one embodiment, the power supply unit 160 can change the voltage level of the second power supply voltage VSS.

[0070] In one embodiment, the power supply unit 160 may measure the voltage level of the second power supply voltage VSS to generate power supply voltage information I_VSS. For example, the power supply unit 160 may measure the voltage at the output terminal that outputs the second power supply voltage VSS to generate power supply voltage information I_VSS. The power supply voltage information I_VSS may be provided to the driving unit 130 (e.g., the data conversion unit 132).

[0071] As described with reference to Figure 1 the display device 100 (or the data conversion unit 132) may use a look-up table LUT to convert the input gray value into a voltage value VDATA on the 2.2 gamma curve, and use, among a plurality of gamma voltages V_GAMMA having a linear relationship with each other, the gamma voltage corresponding to the voltage value VDATA as a data signal (or data voltage) to output. That is, instead of generating a plurality of gamma voltages corresponding to the 2.2 gamma curve, the display device 100 may use a method of using a look-up table LUT (or gamma look-up table) including the relationship between the input gray value and the voltage value set according to the 2.2 gamma curve to convert the input gray value into the voltage value VDATA (furthermore, a method of outputting, among the linear plurality of gamma voltages V_GAMMA, the gamma voltage corresponding to the voltage value VDATA as a data signal).

[0072] In addition, when the dimming value I_DIM is below the reference dimming value, the display device 100 may use a look-up table LUT (or dimming look-up table) to compensate the voltage value VDATA. Therefore, the brightness error of the image displayed by the display device 100 (i.e., the difference between the target brightness and the actual brightness) can be reduced.

[0073] Figure 2 is a block diagram showing an example of the data conversion unit included in the Figure 1 display device.

[0074] Referring to Figure 2 , the data conversion unit 132 may convert the first input gray value I_R0 (or input data value) to output an output data value O_R0 (i.e., the voltage value VDATA described with reference to Figure 1 ).

[0075] The data conversion unit 132 may include a brightness correction unit 210, a first operation unit 220, an interpolation unit 230 (or voltage value calculation unit), a first gamma correction unit 240, a second operation unit 250, a second gamma correction unit 260, a third operation unit 270, and a buffer 280 (or buffer register).

[0076] The luminance correction unit 210, the first arithmetic unit 220, the interpolation unit 230, the first gamma correction unit 240, the second arithmetic unit 250, the second gamma correction unit 260, and the third arithmetic unit 270 can form a data conversion module, and can have the data conversion module in units of pixels PXL (refer to Figure 1 )(or sub-pixels) that make up a unit pixel. For example, when the unit pixel includes a first pixel R0 that emits light of a first color, a second pixel G0 that emits light of a second color, a third pixel B1 that emits light of a third color, and a fourth pixel G1 that emits light of the second color, that is, when the unit pixel includes the first pixel R0, the second pixel G0, the third pixel B1, and the fourth pixel G1 arranged in a PenTile form, the data conversion unit 132 can include a first data conversion module 132a for the first pixel R0, a second data conversion module 132b for the second pixel G0, a third data conversion module 132c for the third pixel B1, and a fourth data conversion module 132d for the fourth pixel G1, respectively.

[0077] Since the first data conversion module 132a to the fourth data conversion module 132d for the first pixel R0 to the fourth pixel G1 are substantially the same or similar to each other, the following includes the first data conversion module 132a to the fourth data conversion module 132d and describes the first data conversion module 132a for the first pixel R0.

[0078] The luminance correction unit 210 can generate a data correction value (or a first data correction value for the first pixel R0) corresponding to the power supply voltage information I_VSS (or the voltage level of the second power supply voltage VSS). Here, the data correction value can represent a correction ratio of the first input gray value I_R0 based on the second power supply voltage VSS, a ratio of the reference voltage level of the second power supply voltage VSS to the current voltage level of the second power supply voltage VSS, etc. The data correction value can be calculated based on the power supply voltage information I_VSS, or the first data correction value corresponding to the power supply voltage information I_VSS can be preset in advance. The smaller the magnitude of the second power supply voltage VSS, the smaller the data correction value can be.

[0079] The first data correction value can be represented by P bits (where P is a natural number). For example, P can be 12. Hereinafter, for the sake of convenience of explanation, it is assumed that P is 12, that is, the first data correction value is 12 bits. Similarly, the first input gray value I_R0 can be represented by Q bits (where Q is a natural number). Hereinafter, it is assumed that Q is 11, that is, the first input gray value I_R0 is 11 bits, and it is assumed that the output data value O_R0 is P bits, that is, 12 bits.

[0080] The first arithmetic unit 220 can perform a multiplication operation on the first input grayscale value I_R0 and the data correction value, thereby outputting the first corrected data value SC_R0. The first arithmetic unit 220 can be implemented by a logic operation circuit. The first arithmetic unit 220 can also be included in the luminance correction unit 210. Through the multiplication operation of the 11-bit first input grayscale value I_R0 and the 12-bit data correction value, the first corrected data value SC_R0 can be represented by 22 bits (i.e., P + Q - 1 bits).

[0081] The interpolation unit 230 can calculate the first voltage value SR_R0 corresponding to the first corrected data value SC_R0 by using the preset gamma lookup table GLUT. Here, the gamma lookup table GLUT can be included in the lookup table LUT described in Figure 1 the reference, and the gamma lookup table GLUT can be provided from the memory 140 to the interpolation unit 230.

[0082] In one embodiment, the interpolation unit 230 can determine the first voltage value range based on the upper R bits of the first corrected data value SC_R0 (where R is a natural number less than P), and interpolate the first voltage value range based on the remaining lower bits of the first corrected data value SC_R0 (e.g., the lower P + Q - 1 - R bits) to generate the first voltage value SR_R0. For example, the interpolation unit 230 can determine the first voltage value range based on the upper 8 bits of the first corrected data value SC_R0, and interpolate the first voltage value range based on the lower 14 bits of the first corrected data value SC_R0 to generate the first voltage value SR_R0.

[0083] For example, the interpolation unit 230 can select specific GLUT data (or the first gamma data) from each gamma lookup table data (or each gamma lookup table data value, hereinafter referred to as "GLUT data") included in the gamma lookup table GLUT based on the upper 8 bits of the first corrected data value SC_R0. That is, the upper 8 bits of the first corrected data value SC_R0 can represent the address of the specific GLUT data.

[0084] On the other hand, the GLUT data included in the gamma lookup table GLUT may include the minimum voltage value of the first voltage value range and the delta voltage value, and the delta voltage value may be the difference between the maximum voltage value and the minimum voltage value of the first voltage value range. For example, the GLUT data may be composed of 21 bits. The upper 12 bits of the GLUT data represent the minimum voltage (or reference voltage, for example, the nth reference voltage, where n is the address of the GLUT data) of the first voltage value range, and the lower 9 bits represent the delta voltage value (for example, the (n + 1)th reference voltage - the nth reference voltage). However, since there is no 256th reference voltage, the 255th delta voltage value may be set to 0. The GLUT data includes the delta voltage value, so that at least one step can be reduced in the operation process of calculating the voltage value (for example, the step of loading the value corresponding to the (n + 1)th reference voltage and calculating the delta voltage value for interpolating the first voltage value range).

[0085] To illustrate the specific operation of the interpolation unit 230, reference may be made to Figure 3 and Figure 4 . Refer to Figure 3 and Figure 4 After explaining the interpolation unit 230, the first gamma correction unit 240 etc. will be explained.

[0086] Figure 3 It is a graph showing the relationship between the input grayscale value and the voltage value provided to the interpolation unit in the data conversion unit included in Figure 2 . Figure 4 It is a diagram explaining the operation of the interpolation unit in the data conversion unit included in Figure 2 .

[0087] Refer to Figure 3 and Figure 4 , the first voltage curve CURVE_V represents the relationship between the upper 8 bits of the first corrected data value SC_R0 and the voltage value VDATA. The first voltage curve CURVE_V may be preset corresponding to the ideal 2.2 gamma curve. Regarding the configuration for setting the first voltage curve CURVE_V, it will be described later with reference to Figures 10 to 12 .

[0088] For example, when the upper 8 bits of the first corrected data value SC_R0 have the value 1, the interpolation unit 230 may determine the range (or interval) of the voltage value VDATA corresponding to the interval between the value 1 and the value 2 as the first voltage value range, and determine the voltage value VDATA corresponding to the value 1 as the minimum voltage value.

[0089] Then, the interpolation unit 230 can perform interpolation (or linear interpolation) on the first voltage value range (i.e., the triangular voltage value of the GLUT data) based on the lower 14 bits of the first corrected data value SC_R0 to calculate the first voltage value SR_R0.

[0090] In one embodiment, the gamma lookup table GLUT may further include a reference voltage value VDATA_BLACK (or black voltage value) that deviates from the first voltage curve CURVE_V. The reference voltage value VDATA_BLACK may be a voltage value corresponding to 0 gray level, or represent the data voltage provided to the pixel PXL that appears black (refer to Figure 1 ) or the voltage value corresponding to the data voltage. The reference voltage value VDATA_BLACK (and the last reference voltage, i.e., the 255th reference voltage) is used as a correction reference in the first gamma correction unit 240 described later, so the reference voltage value VDATA_BLACK can always be output from the interpolation unit 230.

[0091] In each embodiment, the display device 100 (refer to Figure 1 ) can be driven in a first mode (or, normal mode, conventional mode) or a second mode (or low persistence mode, low power mode). Here, the first mode may be a conventional mode in which an image is displayed on the entire display unit 110 (refer to Figure 1 ), and the second mode may be a mode in which an image is displayed only on a part of the display unit 110 (refer to Figure 1 ).

[0092] In the first mode, the interpolation unit 230 can determine the first voltage value range based on the first corrected data value SC_R0 and perform interpolation on the first voltage value range (or triangular voltage value) to output the first voltage value SR_R0. On the other hand, in the second mode, the interpolation unit 230 can output the minimum voltage of the first voltage value range as the first voltage value SR_R0 based on the first corrected data value SC_R0. That is, in the second mode, the interpolation unit 230 can not perform the interpolation operation on the triangular voltage value of the GLUT data, but only output the minimum voltage of the GLUT data as the first voltage value SR_R0. In this case, in the second mode, the power consumption of the display device 100 (refer to Figure 1 ) can be further reduced.

[0093] Refer again to Figure 2, the first gamma correction unit 240 can calculate a first voltage correction value EGRAM_R0 based on the power supply voltage information I_VSS. Here, the first voltage correction value EGRAM_R0 is a value used to compensate for the change in the second power supply voltage VSS for the first voltage value SR_R0 (for example, a value partially deviating from the 2.2 gamma curve). The first voltage correction value EGRAM_R0 can be calculated based on the power supply voltage information I_VSS, or the first voltage correction value EGRAM_R0 corresponding to the power supply voltage information I_VSS can be preset.

[0094] The second arithmetic unit 250 can perform an addition operation on the first voltage value SR_R0 and the first voltage correction value EGRA M_R0 to generate a first corrected voltage value SE_R0. The second arithmetic unit 250 can be included in the first gamma correction unit 240.

[0095] When the first corrected voltage value SE_R0 exceeds the maximum voltage value, the second arithmetic unit 250 can output the maximum voltage value as the first corrected voltage value SE_R0. For example, when the first corrected voltage value SE_R0 exceeds the value 4080, the second arithmetic unit 250 can output the value 4080 as the first corrected voltage value SE_R0. Therefore, overflow of the first corrected voltage value SE_R0 can be prevented.

[0096] When the dimming value I_DIM is less than or equal to the reference dimming value (for example, 100 nit), the second gamma correction unit 260 can select at least one dimming lookup table from a plurality of preset dimming lookup tables based on the dimming value I_DIM, and generate a first dimming correction value WGRAM_R0 based on the at least one dimming lookup table. Here, the dimming lookup table can be included in the lookup table LUT described in Figure 1 the description, and the dimming lookup table can be provided from the memory 140 to the interpolation unit 230, but is not limited thereto.

[0097] On the other hand, when the dimming value I_DIM exceeds the reference dimming value or the display device 100 is driven in the second mode (or low power mode), the second gamma correction unit 260 does not operate.

[0098] As described in Figure 1 the description, as the dimming value I_DIM decreases, the brightness error increases. Therefore, when the dimming value I_DIM is less than or equal to the reference dimming value, the second gamma correction unit 260 can use the dimming lookup table to generate a first dimming correction value WGRAM_R0 for additional compensation of the first corrected voltage value SE_R0.

[0099] To illustrate the operation of the dimming lookup table and the second gamma correction unit 260, reference can be made to Figure 5 andFigure 6 。

[0100] Figure 5 It is a diagram showing an example of a dimming lookup table used in a second gamma correction unit included in a data conversion unit in Figure 2 the data. Figure 6 It is a diagram for explaining Figure 2 the operation of the second gamma correction unit included in the data conversion unit of

[0101] Referring to Figure 5 , dimming lookup tables (P_DIM_SET1 to P_DIM_SET8) can be set for specific dimming values (or specific brightness levels). For example, the first dimming lookup table P_DIM_SET1 can be set corresponding to a brightness of 10 nit, the second dimming lookup table P_DIM_SET2 can be set corresponding to a brightness of 20 nit, the eighth dimming lookup table P_DIM_SET8 can be set corresponding to a brightness of 100 nit, and the third dimming lookup table P_DIM_SET3 to the seventh dimming lookup table P_DIM_SET7 can be set at 20 nit brightness intervals.

[0102] On the other hand, Figure 5 shows a case where eight dimming lookup tables (P_DIM_SET1 to P_DIM_SET8) are set at 10 nit or 20 nit brightness intervals, but this is just an example, and the dimming lookup tables (P_DIM_SET1 to P_DIM_SET8) are not limited to this. For example, the number of dimming lookup tables (P_DIM_SET1 to P_DIM_SET8) can be seven or less or nine or more, and the dimming lookup tables (P_DIM_SET1 to P_DIM_SET8) can also be set at brightness intervals of 10 nit or less or 20 nit or more.

[0103] Each of the dimming lookup tables (P_DIM_SET1 to P_DIM_SET8) can include gamma correction values set corresponding to respective representative gray values. Here, the representative gray values can be arbitrarily set among all the input gray values included in the gray range of the first input gray value I_R0. For example, the number of representative gray values can be 30. The number of representative gray values can be twice or more the number of tags (for example, 10) included in the gamma voltage generation unit 133 (refer to Figure 1 ). This is to more accurately compensate for a specific brightness range where brightness degradation (i.e., a phenomenon such as emitting light at a brightness lower than the target brightness) occurs when driving the display device 100 in a dimming drive mode.

[0104] In the first dimming lookup table P_DIM_SET1, the first gamma correction value p_s1_r / g / b00 is the gamma correction value relative to the first representative gray value, and may include the gamma correction value for the first pixel R0 described for reference Figure 2 the gamma correction value for the second pixel G0, and the gamma correction value for the third pixel B1. Similarly, the second gamma correction value p_s1_r / g / b01 may be the gamma correction value relative to the second representative gray value. That is, the k-th gamma correction value p_s1_r / g / bk (where k is an integer greater than 2 and less than 30) may be the gamma correction value relative to the k-th representative gray value.

[0105] Similarly, in the second dimming lookup table P_DIM_SET2, the first gamma correction value p_s2_r / g / b00 may be the gamma correction value relative to the first representative gray value, and the second gamma correction value p_s2_r / g / b01 may be the gamma correction value relative to the second representative gray value. That is, the k-th gamma correction value p_s2_r / g / bk may be the gamma correction value relative to the k-th representative gray value.

[0106] On the other hand, each gamma correction value included in the eighth dimming lookup table P_DIM_SET8 may be 0. The eighth dimming lookup table P_DIM_SET8 may be generated for the interpolation operation of the second gamma correction unit 260.

[0107] When the dimming value I_DIM corresponds to a specific brightness (i.e., one of the brightnesses for which the dimming lookup table is set), the dimming lookup table corresponding to the specific brightness may be selected. However, when the dimming value I_DIM is different from the specific brightness, the second gamma correction unit 260 may select two dimming lookup tables.

[0108] Referring to Figure 6 , the second gamma correction unit 260 may select two adjacent dimming lookup tables (for example, the m-th dimming lookup table and the n-th dimming lookup table, where n = m + 1) based on the dimming value I_DIM, and interpolate each gamma voltage (or each corresponding gamma voltage) included in the two dimming lookup tables to generate an interpolated dimming lookup table P_DIM_SET_C (or an interpolated lookup table).

[0109] For example, when the dimming value I_DIM corresponds to 15 nit, the second gamma correction unit 260 may select a first dimming lookup table P_DIM_SET1 corresponding to 10 nit and a second dimming lookup table P_DIM_SET2 corresponding to 20 nit, and interpolate the first gamma correction values p_s1_r / g / b00 of the first dimming lookup table P_DIM_SET1 and the first gamma correction values p_s2_r / g / b00 of the second dimming lookup table P_DIM_SET2 to generate the first gamma correction value cset_r / g / b00 of the interpolated dimming lookup table P_DIM_SET_C. The second gamma correction unit 260 may round off the first gamma correction value cset_r / g / b00 so that the first gamma correction value cset_r / g / b00 of the interpolated dimming lookup table P_DIM_SET_C has the same size (e.g., 12 bits) as the first gamma correction value p_s1_r / g / b00 of the first dimming lookup table P_DIM_SET1.

[0110] Similarly, the second gamma correction unit 260 may interpolate the second gamma correction values p_s1_r / g / b01 of the first dimming lookup table P_DIM_SET1 and the second gamma correction values p_s2_r / g / b01 of the second dimming lookup table P_DIM_SET2 to generate the second gamma correction value cset_r / g / b01 of the interpolated dimming lookup table P_DIM_SET_C, and generate the interpolated dimming lookup table P_DIM_SET_C.

[0111] On the other hand, when the dimming value I_DIM is less than the minimum dimming value (for example, when the dimming value I_DIM is less than 10 nit), the second gamma correction unit 260 may select the first dimming lookup table P_DIM_SET1.

[0112] In addition, when the dimming value I_DIM changes, a selection of at least one dimming lookup table among the dimming lookup tables (P_DIM_SET1 to P_DIM_SET8) and a generation operation of the interpolated dimming lookup table P_DIM_SET_C may be performed.

[0113] In each embodiment, the second gamma correction unit 260 may interpolate each gamma correction value (cset_r / g / b00 to cset_r / g / b29) of the interpolated dimming lookup table P_DIM_SET_C to calculate the first dimming correction value WGRAM_R0 in the entire range.

[0114] In one embodiment, the second gamma correction unit 260 may perform a subtraction operation on adjacent gamma correction values in the interpolated dimming lookup table P_DIM_SET_C to calculate differential gamma correction values. For example, the second gamma correction unit 260 may perform a subtraction operation on the second gamma correction value cset_r / g / b01 and the first gamma correction value cset_r / g / b00 to calculate the first differential gamma correction value cdiff_r / g / b00.

[0115] The corresponding gamma correction values and differential gamma correction values may have an address Addr. For example, the first gamma correction value cset_r / g / b00 and the first differential gamma correction value cdiff_r / g / b00 may have a first address value of 0, and the second gamma correction value cset_r / g / b01 and the second differential gamma correction value cdiff_r / g / b01 may have a second address value (p_r / g / b_cadr_01).

[0116] On the other hand, the first input grayscale value I_R0 provided to the data conversion unit 132 may be used as the address Addr of the gamma correction values and differential gamma correction values in the interpolated dimming lookup table P_DIM_SET_C.

[0117] In one embodiment, the second gamma correction unit 260 may generate a first dimming correction value WGRAM_R0 according to the following mathematical formula 1.

[0118] [Mathematical formula 1]

[0119] WGRAM_R0 = cset_rN + cdiff_rN * (I_R0 - p_r_card_N) / (p_r_card_N + 1 - p_r_card_N)

[0120] Here, N is a natural number, cset_rN is the Nth gamma correction value, and cdiff_rN is the Nth differential gamma correction value.

[0121] For example, when the address based on the first input grayscale value I_R0 is greater than the second address value p_r / g / b_cadr_01 and less than the third address value p_r / g / b_cadr_02, the second gamma correction value cset_r / g / b01 and the second differential gamma correction value cdiff_r / g / b01 based on the second address value p_r / g / b_cadr_01 can be used in the generation of the first dimming correction value WGRAM_R0. In this case, the second gamma correction unit 260 can substitute the first input grayscale value I_R0, the second address value p_r / g / b_cadr_01, the third address value p_r / g / b_cadr_02, the second gamma correction value cset_r / g / b01, and the second differential gamma correction value cdiff_r / g / b01 into the mathematical formula 1, so as to calculate the first dimming correction value WGRAM_R0 relative to the first corrected voltage value SE_R0.

[0122] The third arithmetic unit 270 can perform an addition operation on the first corrected voltage value SE_R0 and the first dimming correction value WGRAM_R0 to generate the first output voltage value SPG_R0. The third arithmetic unit 270 can be included in the second gamma correction unit 260.

[0123] When the first output voltage value SPG_R0 exceeds the maximum voltage value, the third arithmetic unit 270 can output the maximum voltage value as the first output voltage value SPG_R0. For example, when the first output voltage value SPG_R0 exceeds the value 4080, the third arithmetic unit 270 can output the value 4080 as the first output voltage value SPG_R0. Therefore, overflow of the first output voltage value SPG_R0 can be prevented.

[0124] The buffer 280 can output the first output voltage value SPG_R0 as the output data value O_R0 (or the voltage value VDATA referred to Figure 1 in the description). For example, the output data value O_R0 can also include the first output voltage value SPG_R0 of the first data conversion module 132a, the second output voltage value of the second data conversion module 132b, the second output voltage value of the third data conversion module 132c, and the output voltage value of the fourth data conversion module 132d.

[0125] On the other hand, the buffer 280 can also directly receive the first input grayscale value I_R0. For example, when the data conversion unit 132 does not need to work, the buffer 280 can also output the first input grayscale value I_R0 as the output data value O_R0. That is, according to the need, the buffer 280 can skip the first input grayscale value I_R0.

[0126] As referred to Figures 2 to 6As described, the data conversion unit 132 can use the gamma lookup table GLUT to convert the input grayscale value into an output data value on the 2.2 gamma curve. Additionally, when the dimming value I_DIM is below the reference dimming value, the data conversion unit 132 can use the dimming lookup table to additionally compensate the output data value. Therefore, the brightness error (i.e., the difference between the target brightness and the actual brightness) of the image displayed by the display device 100 can be reduced.

[0127] On the other hand, in Figure 2 it is shown that the data conversion unit 132 includes the brightness correction unit 210 (and the first operation unit 220) and the first gamma correction unit 240 (and the second operation unit 250), but the present invention is not limited thereto.

[0128] For example, in the case where the power supply unit 160 (refer to Figure 1 ) generates the second power supply voltage VSS having a fixed voltage level, the data conversion unit 132 may not include the brightness correction unit 210 (and the first operation unit 220) and the first gamma correction unit 240 (and the second operation unit 250). In this case, it may be that the first input grayscale value I_R0 is directly provided to the interpolation unit 230, and the first voltage value SR_R0 generated by the interpolation unit 230 is directly provided to the third operation unit 270 (or the second gamma correction unit 260).

[0129] Figure 7 is a chart showing a comparison example of the brightness curve representing Figure 1 the brightness corresponding to each grayscale of the display device. Figure 8 is a chart showing an example of the brightness curve of the Figure 1 display device.

[0130] First, referring to Figure 1 and Figure 7 , the gamma voltage generation unit related to the comparative example can divide the reference voltages VGS and VREG by a ladder resistance to generate each gamma voltage corresponding to the 2.2 gamma curve.

[0131] In particular, the gamma voltage generation unit related to the comparative example can generate each reference gamma voltage corresponding to partial tabulation points (for example, six tabulation points corresponding to 255 grayscale, 203 grayscale, etc.), and linearly interpolate each reference gamma voltage to generate each gamma voltage. In this case, the comparative brightness curve CURVE_L_C of the display device based on each gamma voltage may have a brightness error based on the brightness curve of the ideal 2.2 gamma curve due to linear changes occurring between each tabulation point.

[0132] The first error curve CURVE_E1 represents the luminance error corresponding to each gray level based on the comparative luminance curve CURVE_L_C of the comparative example. Along the first error curve CURVE_E1, the luminance error at each gamma tabulation point approaches 0, but as it gradually moves away from the tabulation point, the maximum luminance error that occurs reaches 8%. This luminance error will be manifested as a display quality error and may be recognized by the user.

[0133] On the other hand, referring to Figure 1 , Figure 7 and Figure 8 , the gamma voltage generation unit 133 according to each embodiment of the present invention can generate each gamma voltage by dividing the reference voltages VGS and VREG through a ladder resistance, and the data conversion unit 132 can convert the first input gray value I_R0 into an output data value O_R0 corresponding to a 2.2 gamma curve. That is, through the data conversion unit 132, each gamma voltage can be digitally made to coincide with the luminance curve CURVE_L corresponding to the ideal 2.2 gamma curve (i.e., curve fitting). In this case, the gamma voltage generation unit 133 can set each tabulation point regardless of the inflection point on the 2.2 gamma curve, so the number of tabulation points can be reduced.

[0134] Referring again to Figure 7 , the second error curve CURVE_E2 represents the luminance error corresponding to each gray level based on the luminance curve CURVE_L of the embodiment of the present invention. Along the second error curve CURVE_E2, it is shown that the luminance error within the entire gray level range can approach 0. This can be manifested as a relative display quality improvement.

[0135] Hereinafter, with reference to Figures 9 to 12 , the process of generating the gamma lookup table GLUT (refer to Figure 2 )(and GLUT data) will be described.

[0136] Figure 9 is a diagram showing an example of a plurality of gamma voltages generated by the gamma voltage generation unit included in the Figure 1 display device. Figure 10 is a diagram showing the relationship between the input gray value and the voltage value obtained through optical compensation of the Figure 1 display device. Figure 11 is a diagram obtained by differentiating the Figure 10 diagram once. Figure 12 is a diagram showing the process of performing additional correction on the Figure 10 diagram.

[0137] First, refer to Figure 1 and Figure 9 , the first gamma voltage curve CURVE_GR (or the first color gamma voltage curve) represents the first gamma voltage (or the first color gamma voltage) corresponding to the gray level of the first pixel that emits light in the first color, the second gamma voltage curve CURVE_GG (or the second color gamma voltage curve) represents the second gamma voltage (or the second color gamma voltage) corresponding to the gray level of the second pixel that emits light in the second color, and the third gamma voltage curve CURVE_GB (or the third color gamma voltage curve) represents the third gamma voltage (or the third color gamma voltage) corresponding to the gray level of the third pixel that emits light in the third color.

[0138] Along the first gamma voltage curve CURVE_GR, the first gamma voltages can have a linear relationship with each other. That is, as the gray level value increases, the first gamma voltage can decrease linearly. Similarly, along the second gamma voltage curve CURVE_GG, the second gamma voltages can have a linear relationship with each other, and along the third gamma voltage curve CURVE_GB, the third gamma voltages can have a linear relationship with each other.

[0139] That is, the gamma voltage generation unit 133 can generate the first gamma voltage, the second gamma voltage, and the third gamma voltage that have a linear relationship with each other regardless of the 2.2 gamma curve.

[0140] Refer to Figure 9 and Figure 10 , and by optical compensation for the display device 100, the output data value (or the seed for generating the GLUT) can be extracted.

[0141] For example, the voltage value VDATA for a specific tab point (or a specific gray level value) can be determined by multi-time programming (MTP) of the display device 100, and the determined voltage values VDATA are linearly connected, so that all voltage values VDATA can be derived. That is, the first voltage curve CURVE_VR (or the first gray level-voltage curve) including the first gamma voltage, the second voltage curve CURVE_VG including the second gamma voltage, and the third voltage curve CURVE_VB including the third gamma voltage can be derived.

[0142] On the other hand, in multiple programming processes, the ratio of voltage to luminance (or the ratio of voltage to luminance) at each specific tabulation point can be calculated. Here, the ratio of voltage to luminance represents the ratio of the change in voltage to the change in luminance, and can be used in the correction of the first voltage curve CURVE_VR to the third voltage curve CURVE_VB, which will be referred to Figure 12 as described later.

[0143] referred to Figure 11 , by taking the first derivative of each of the first voltage curve CURVE_VR to the third voltage curve CURVE_VB respectively, the differential voltage curve CURVE_V_D can be derived. In Figure 11 , the differential voltage curve CURVE_V_D for one of the voltage curves among the first voltage curve CURVE_VR to the third voltage curve CURVE_VB is illustrated. The differential voltage curves of the remaining voltage curves among the first voltage curve CURVE_VR to the third voltage curve CURVE_VB can be represented similarly to the differential voltage curve CURVE_V_D.

[0144] The differential voltage curve CURVE_V_D can be divided into a first section SECTION1 to a fourth section SECTION4 according to the gray value. For example, taking the inflection point of the differential voltage curve CURVE_V_D (or the first voltage curve CURVE_VR) as a reference, each tabulation point is set, and the first section SECTION1 to the fourth section SECTION4 can be divided based on each tabulation point.

[0145] The first section SECTION1 is a high gray level section corresponding to a relatively large gray value. In the first section SECTION1, the differential voltage curve CURVE_V_D can have a constant value independent of the change in the gray value. That is, in the first section SECTION1, the value of the differential voltage curve CURVE_V_D (or the differential value of the first voltage curve CRUVE_VR (refer to Figure 10 )) can be set or adjusted to a constant value.

[0146] The second section SECTION2 is an intermediate gray level section corresponding to a relatively intermediate gray value. In the second section SECTION2, the differential voltage curve CURVE_V_D can have a value that decreases as the gray value increases. That is, in the second section SECTION2, the differential voltage curve CURVE_V_D can be represented by a linear equation, or adjusted to be representable by a linear equation.

[0147] The third section, SECTION3, is a low gray level section corresponding to a relatively low gray level value. In the third section, SECTION3, the differential voltage curve, CURVE_V_D, can be represented by a quadratic equation or adjusted to be represented by a quadratic equation.

[0148] The fourth section, SECTION4, is an extremely low gray level section corresponding to the minimum gray level value. In the fourth section, SECTION4, the differential voltage curve, CURVE_V_D, can be represented by a multi-order equation.

[0149] Then, the voltage curve for the voltage value VDATA (e.g., Figure 10 the first voltage curve, CURVE_VR, as shown) can be reset or corrected based on the adjusted differential value.

[0150] On the other hand, Figure 11 illustrates the case where the value of the differential voltage curve, CURVE_V_D, is set based on four tabulation points (or the first section, SECTIONI1 to the fourth section, SECTION4), but it is not limited to this. For example, the differential voltage curve, CURVE_V_D, can also be reset based on the differential values at the intermediate gray level values of the first section, SECTIONI1 to the third section, SECTION3 (i.e., three additional tabulation points) and the differential values at the initial four tabulation points. That is, curve fitting for the voltage curve (e.g., the first voltage curve, CURVE_VR (refer to Figure 10 )) can also be performed through seven tabulation points.

[0151] In each embodiment, additional correction for the voltage curve (e.g., the first voltage curve, CURVE_VR) can be performed based on the ratio of voltage to luminance calculated in the multi-programming process described in Figure 10 With reference to

[0152] With reference to Figure 1 and Figure 12 the actual luminance curve, CURVE_M, of the display device 100 driven by the gamma voltage based on the first voltage curve, CURVE_VR, may have a luminance error, ERROR, at some gray level values with respect to the ideal luminance curve, CURVE_L0, as a reference.

[0153] As Figure 12As shown, when curve fitting for the first voltage curve CURVE_VR is performed through multiple programming for the 121 gray value 121G and the 195 gray value 195G, the actual brightness curve CURVE_M may have a brightness error ERROR at the middle gray value (e.g., the 158 gray value 158G). In this case, based on the ratio of voltage to brightness (V2L) at the 121 gray value 121G and the ratio of voltage to brightness at the 195 gray value 195G, additional correction for the actual brightness curve CURVE_M can be performed. For example, interpolate the ratio of voltage to brightness (V2L) at the 121 gray value 121G and the ratio of voltage to brightness at the 195 gray value 195G to calculate the ratio of voltage to brightness at the 158 gray value 158G, and set the additional voltage correction value corresponding to the brightness error ERROR based on the ratio of voltage to brightness at the 158 gray value 158G. Thus, a brightness curve CURVE_L (or the brightness curve after additional correction) similar to the 2.2 gamma curve can be derived.

[0154] The additional voltage correction value between the 121 gray value 121G and the 195 gray value 195G can be set and stored as an offset Offset. For example, the offset Offset can be reflected in the GLUT gamma data described in Figure 2 the reference.

[0155] The offset Offset can be set as shown in the offset curve CURVE_OFFSET in Figure 12 For example, the offset curve CURVE_OFFSET can be expressed as the square of the gray value (i.e., y = x^2) with the 158 gray value 158G as the reference between the 121 gray value 121G and the 195 gray value 195G.

[0156] Since the brightness error curve CURVE_ERROR representing the brightness error ERROR is compensated by the compensation curve CURVE_COMP based on the offset Offset, the compensated error can substantially have a value of 0 or be eliminated.

[0157] As described in the reference in Figures 9 to 12 the gamma lookup table GLUT (and GLUT data) can be generated through the linear setting step of the gamma voltage, the seed extraction step for GLUT generation through optical compensation, the setting step of the voltage curve using the differential value (i.e., the curve fitting step), and the additional correction step using the ratio of voltage to brightness V2L (i.e., the offset setting step of the GLUT data).

[0158] Figure 13 represents for Figure 1Diagram of the offset of the dimming lookup table used in the second gamma correction unit included in the display device. Figure 14 is a diagram showing the change of the luminance curve based on the offset set in Figure 13 .

[0159] First, referring to Figure 13 , the table may include offsets for representative gray values (or tabulation points). The offset Offset may be set based on 35 gray values (or 65 gray values when the display device 100 (refer to Figure 1 ) is driven in the dimming drive mode) and a dimming level (DataDim) (or dimming value) of 2.

[0160] In other words, for the display device 100 driven by dimming with a dimming level of 2, programming can be performed multiple times on 65 gray values to calculate the offset Offset used in the dimming lookup table. Additionally, the corresponding offset Offset can be interpolated based on the dimming level and the gray value to calculate the offset Offset for all representative gray values.

[0161] For example, it can be that as the gray value increases, the offset Offset is set to be proportional to the square root of the gray value (i.e., Offset^1 / 2), and as the gray value decreases, the offset Offset is set to be proportional to the gray value (i.e., Offset*ratio).

[0162] The calculated offset Offset can be reflected in the dimming lookup table (P_DIM_SET1 to P_DIM_SET8) described with reference to Figure 5 .

[0163] Referring to Figure 14 , the luminance curves (CURVE_L1, CURVE_L2) of the display device 100 driven at a luminance of 2 nit (i.e., a dimming level of 2) are shown.

[0164] The first luminance curve CURVE_L1 represents the luminance corresponding to each gray value of the display device 100 operating with a dimming lookup table based on the offset Offset not reflected in the reference Figure 13 description, and the second luminance curve CURVE_L2 represents the luminance corresponding to each gray value of the display device 100 operating with a dimming lookup table based on the offset Offset reflected in the reference Figure 13 description. Compared with the first luminance curve CURVE_L1, in the second luminance curve CURVE_L2, the voltage values corresponding to the 23 gray value are set relatively low, and the display device 100 can display an image that more conforms to the ideal 2.2 gamma curve.

[0165] Figure 15is a diagram showing an example of a pixel in a display device included in Figure 1 The pixel PXL may include a first transistor T1 to a seventh transistor T7, a storage capacitor Cst, and a light-emitting element LD.

[0166] Referring to Figure 15 the pixel PXL may include a first transistor T1 to a seventh transistor T7, a storage capacitor Cst, and a light-emitting element LD.

[0167] The first transistor T1 to the seventh transistor T7 may each be implemented by a P-type transistor, but are not limited thereto. For example, at least a part of the first transistor T1 to the seventh transistor T7 may be implemented by an N-type transistor.

[0168] The first electrode of the first transistor T1 (drive transistor) may be connected to the second node N2, or connected to the first power supply line (i.e., the power supply line to which the first power supply voltage VDD is applied) via the fifth transistor T5. The second electrode of the first transistor T1 may be connected to the first node N1, or connected to the anode of the light-emitting element LD via the sixth transistor T6. The gate electrode of the first transistor T1 may be connected to the third node N3. The first transistor T1 may control the amount of current flowing from the first power supply line through the light-emitting element LD to the second power supply line (i.e., the power supply line that transmits the second power supply voltage VSS) corresponding to the voltage of the third node N3.

[0169] The second transistor T2 (switching transistor) may be connected between the data line DLj and the second node N2. The gate electrode of the second transistor T2 may be connected to the scan line SLi. The second transistor T2 may be turned on when a scan signal is supplied to the scan line SLi, thereby electrically connecting the data line DLj and the first electrode of the first transistor T1.

[0170] The third transistor T3 may be connected between the first node N1 and the third node N3. The gate electrode of the third transistor T3 may be connected to the scan line SLi. The third transistor T3 may be turned on when a scan signal is supplied to the scan line SLi to electrically connect the first node N1 and the third node N3. Therefore, when the third transistor T3 is turned on, the first transistor T1 may be connected in a diode form.

[0171] The storage capacitor Cst may be connected between the first power supply line and the third node N3. The storage capacitor Cst may store a data signal and a voltage corresponding to the threshold voltage of the first transistor T1.

[0172] The fourth transistor T4 can be connected between the third node N3 and the initialization power supply line (i.e., the power supply line that transmits the initialization power supply voltage Vint). The gate electrode of the fourth transistor T4 can be connected to the previous scan line SLi-1. The fourth transistor T4 can be turned on when supplying a scan signal to the previous scan line SLi-1, so as to supply the initialization power supply voltage Vint to the first node N1. Here, the initialization power supply voltage Vint can be set to have a voltage level lower than that of the data signal.

[0173] The fifth transistor T5 can be connected between the first power supply line and the second node N2. The gate electrode of the fifth transistor T5 can be connected to the light emission control line Eli. The fifth transistor T5 can be turned off when supplying a light emission control signal to the light emission control line Eli, and turned on in other cases.

[0174] The sixth transistor T6 can be connected between the first node N1 and the light emitting element LD. The gate electrode of the sixth transistor T6 can be connected to the light emission control line Eli. The sixth transistor T6 can be turned off when supplying a light emission control signal to the light emission control line Eli, and turned on in other cases.

[0175] The seventh transistor T7 can be connected between the initialization power supply line and the anode of the light emitting element LD. The gate electrode of the seventh transistor T7 can be connected to the scan line SLi. The seventh transistor T7 can be turned on when supplying a scan signal to the scan line SLi, so as to supply the initialization power supply voltage Vint to the anode of the light emitting element LD.

[0176] The anode of the light emitting element LD can be connected to the first transistor T1 via the sixth transistor T6, and the cathode can be connected to the second power supply line. The light emitting element LD can generate light of a predetermined brightness corresponding to the current supplied from the first transistor T1. The first power supply voltage VDD can be set to have a voltage level higher than that of the second power supply voltage VSS, so that current flows to the light emitting element LD.

[0177] The scope of the present invention is not limited to the content detailed in the specification, and should be defined only by the claims. In addition, it should be interpreted that all changes or variations derived from the meaning, scope and equivalent concepts of the claims are included in the scope of the present invention.

Claims

1. A display device, comprising: a display panel including a plurality of pixels; a power supply unit supplying a first power supply voltage and a second power supply voltage required for driving each of the pixels; a luminance correction unit generating a first data correction value corresponding to a voltage level of the second power supply voltage, and performing a multiplication operation on a first input data value and the first data correction value to output a first corrected data value; an interpolation unit calculating a first voltage value corresponding to the first corrected data value by using a set gamma look-up table; a first gamma correction unit calculating a first voltage correction value corresponding to the voltage level of the second power supply voltage, and performing an addition operation on the first voltage value and the first voltage correction value to calculate a first output data value; a gamma voltage generation unit generating a plurality of gamma voltages having a linear relationship; and a data driving unit selecting a first gamma voltage from among the plurality of gamma voltages based on the first output data value, and providing the first gamma voltage as a data voltage to the display panel, wherein the first data correction value is represented by P bits, where P is a natural number, the first input data value is represented by Q bits, where Q is a natural number, the first corrected data value is represented by P + Q - 1 bits, the interpolation unit determining a first voltage value range based on upper R bits of the first corrected data value, and interpolating the first voltage value range based on remaining lower bits of the first corrected data value to generate the first voltage value, where R is a natural number less than P.

2. The display device according to claim 1, wherein the gamma look-up table includes first gamma data, the first gamma data includes a minimum voltage value of the first voltage value range and a triangular voltage value, the triangular voltage value is a difference between a maximum voltage value and the minimum voltage value of the first voltage value range.

3. The display device according to claim 2, wherein the interpolation unit interpolates the triangular voltage value of the first gamma data based on remaining bits in the first corrected data value.

4. The display device according to claim 1, further comprising: a second gamma correction unit selecting at least one dimming look-up table from among a set of dimming look-up tables based on a dimming value, and correcting the first output data value based on the at least one dimming look-up table to output a first corrected voltage value, wherein the data driving unit receives the first corrected voltage value as the first output data value.

5. The display device according to claim 4, wherein the plurality of dimming look-up tables each include gamma correction values set corresponding to respective representative gray values, the second gamma correction unit selects a first dimming look-up table and a second dimming look-up table based on the dimming value, and interpolates the gamma correction value in the first dimming look-up table and the gamma correction value in the second dimming look-up table based on the dimming value to generate an interpolated look-up table, and corrects the corrected voltage value by using the interpolated look-up table.

6. The display device according to claim 5, wherein The number of the representative gray values is more than twice the number of reference marks included in the gamma voltage generation unit.

7. The display device according to claim 5, wherein The second gamma correction unit interpolates the correction values in the interpolated look-up table to generate gamma correction values for the first corrected voltage values, and performs an addition operation on the first corrected voltage values and the gamma correction values.

8. The display device according to claim 5, wherein Each of the plurality of dimming look-up tables further includes an offset set for a first representative gray value among the plurality of representative gray values, Based on the first representative gray value, it is set such that as the gray value increases, the offset is proportional to the square root of the gray value, and as the gray value decreases, the offset is proportional to the gray value.

9. The display device according to claim 1, wherein The plurality of gamma voltages have a first-order linear relationship with respect to the first output data value.

10. The display device according to claim 1, wherein The first input data value and the first output data value are located on a gray-scale - voltage curve, The differential value of the gray-scale - voltage curve has a constant value in a first interval and is represented as a first-order equation in a second interval, The input data value corresponding to the first interval is greater than the input data value corresponding to the second interval.

11. The display device according to claim 10, wherein The differential value is represented as a second-order equation in a third interval, The input data value corresponding to the third interval is less than the input data value corresponding to the second interval.

12. The display device according to claim 10, wherein A reference differential value with respect to a representative gray value is determined during an optical compensation process for setting a data voltage with respect to the representative gray value, The constant value and the first-order equation are set based on the differential value.

13. A display device, comprising: A display panel including a plurality of pixels; An interpolation unit that uses a set gamma look-up table to generate a first voltage value corresponding to an input data value; A gamma correction unit that selects at least one dimming look-up table from a plurality of set dimming look-up tables based on a dimming value, and corrects the first voltage value based on the at least one dimming look-up table to calculate a first output data value; A gamma voltage generation unit that generates a plurality of gamma voltages having a linear relationship; And A data driving unit that selects a first gamma voltage from among the plurality of gamma voltages based on the first output data value, and provides the first gamma voltage as a data voltage to the display panel, The interpolation unit determines a first voltage value range based on the upper R bits of the input data value, and interpolates the first voltage value range based on the remaining bits of the input data value to generate the first voltage value, where R is a natural number, Each of the plurality of dimming look-up tables includes a plurality of gamma correction values respectively set corresponding to each representative gray value.

14. The display device according to claim 13, wherein The gamma correction unit selects a first dimming lookup table and a second dimming lookup table from among the multiple dimming lookup tables based on the dimming value, and interpolates multiple gamma correction values in the first dimming lookup table and multiple gamma correction values in the second dimming lookup table based on the dimming value to generate an interpolated lookup table, and uses the interpolated lookup table to correct the corrected voltage value.

15. The display device according to claim 14, wherein the gamma correction unit interpolates multiple correction values in the interpolated lookup table to generate a gamma correction value for the first voltage value, and performs an addition operation on the first voltage value and the gamma correction value.

16. The display device according to claim 13, wherein the gamma lookup table includes first gamma data, the first gamma data includes a minimum voltage value and a triangular voltage value of the first voltage value range, the triangular voltage value is the difference between the maximum voltage value and the minimum voltage value of the first voltage value range.

17. The display device according to claim 16, wherein the interpolation unit interpolates the triangular voltage value of the first gamma data based on the remaining bits in the input data value.

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