Source driver and display device including the same

Abstract

A source driver and a display device including the source driver are disclosed. The source driver includes a gamma voltage generating circuit and a data voltage generating circuit. The gamma voltage generating circuit generates a gamma voltage and changes the gamma voltage based on a driving frequency. The data voltage generating circuit generates a data voltage based on the gamma voltage.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0019335, filed on February 19, 2019, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a display device, and more particularly, to a source driver and a display device including the source driver. Background Art

[0004] A display device generally includes a source driver and a display panel. The source driver generates a gamma voltage representing each possible grayscale value and converts externally provided digital input data into an analog data signal using the gamma voltage. The pixels included in the display panel emit light at a brightness corresponding to the data signal provided thereto.

[0005] The source driver sets a reference gamma voltage corresponding to a corresponding grayscale value based on a gamma characteristic of a pixel, and divides the reference gamma voltage to generate a gamma voltage for each grayscale value. Summary of the invention

[0006] The display device operates during the changing driving frequency to reduce power consumption. However, when changing the driving frequency, the optical characteristics of the display device may change, and these changes are observable to the viewer, thereby reducing the perceived image quality.

[0007] Exemplary embodiments of the present invention provide a source driver capable of maintaining constant optical characteristics even if a driving frequency is variable, and a display device including the source driver.

[0008] According to an exemplary embodiment of the present invention, the source driver includes a gamma voltage generating circuit and a data voltage generating circuit. The gamma voltage generating circuit generates a gamma voltage and changes the gamma voltage based on a driving frequency. The data voltage generating circuit generates a data voltage based on the gamma voltage.

[0009] According to an exemplary embodiment of the present invention, the source driver may further include a frequency determination circuit that determines a driving frequency based on the image data.

[0010] According to an exemplary embodiment of the present invention, a gamma voltage generating circuit may include a first gamma voltage generator, an offset setter, and a second gamma voltage generator, the first gamma voltage generator generating a first gamma voltage based on a reference gamma voltage set corresponding to a reference frequency, the offset setter generating a gamma voltage offset based on a reference gamma voltage offset set corresponding to a driving frequency, and the second gamma voltage generator generating a second gamma voltage based on the first gamma voltage and the gamma voltage offset. The number of the reference gamma voltage offsets may be less than the number of the gamma voltage offsets. The number of the second gamma voltage may be equal to the number of the gamma voltage offsets.

[0011] According to an exemplary embodiment of the present invention, the number of reference gamma voltage shifts may be smaller than the number of reference gamma voltages.

[0012] According to an exemplary embodiment of the present invention, the offset setter may generate the gamma voltage offsets by interpolating the reference gamma voltage offsets.

[0013] According to an exemplary embodiment of the present invention, the offset setter may determine a first adjacent frequency and a second adjacent frequency adjacent to the driving frequency, and may set a reference gamma voltage offset by interpolating a preset first adjacent reference gamma offset corresponding to the first adjacent frequency and a preset second adjacent reference gamma offset corresponding to the second adjacent frequency.

[0014] According to an exemplary embodiment of the present invention, the gamma voltage generating circuit may further include a selector which outputs the first gamma voltage or the second gamma voltage.

[0015] According to an exemplary embodiment of the present invention, the reference gamma voltage offset may further include a first color reference gamma voltage offset, a second color reference gamma voltage offset, and a third color reference gamma voltage offset.

[0016] According to an exemplary embodiment of the present invention, the reference gamma voltage offset may be an inflection point of a curve configured by the gamma voltage offset.

[0017] According to an exemplary embodiment of the present invention, the gamma voltage generating circuit may further include a storage device storing information about the reference gamma voltage and information about the reference gamma voltage offset.

[0018] According to an exemplary embodiment of the present invention, a gamma voltage generating circuit may include an offset setter, a gamma voltage control signal generator, and a gamma voltage generator, the offset setter generating a second reference gamma voltage offset based on a first reference gamma voltage offset set corresponding to a driving frequency, the gamma voltage control signal generator setting a second reference gamma voltage based on a preset first reference gamma voltage and a second reference gamma voltage offset, and the gamma voltage generator generating a second gamma voltage based on the second reference gamma voltage. The number of the first reference gamma voltage offsets may be less than the number of the second reference gamma voltage offsets. The number of the first reference gamma voltage offsets may be equal to the number of the second reference gamma voltage offsets.

[0019] According to an exemplary embodiment of the present invention, the offset setter may generate the second reference gamma voltage offset by interpolating the first reference gamma voltage offset. The gamma voltage control signal generator may generate the second reference gamma voltage by adding the first reference gamma voltage and the second reference gamma voltage offset together.

[0020] A display device according to an exemplary embodiment of the present invention includes a display unit and a source driver. The display unit includes pixels. The source driver generates a data voltage based on image data and provides the data voltage to the pixels. The source driver includes a gamma voltage generating circuit, which generates a gamma voltage and changes the gamma voltage based on a driving frequency. The data voltage generating circuit is configured to generate a data voltage based on the gamma voltage.

[0021] According to an exemplary embodiment of the present invention, a gamma voltage generating circuit may include a first gamma voltage generator, an offset setter, and a second gamma voltage generator. The first gamma voltage generator generates a first gamma voltage based on a reference gamma voltage set corresponding to a reference frequency. The offset setter generates a gamma voltage offset based on a reference gamma voltage offset set corresponding to a driving frequency. The second gamma voltage generator generates a second gamma voltage based on the first gamma voltage and the gamma voltage offset. The number of reference gamma voltage offsets may be less than the number of gamma voltage offsets. The number of second gamma voltages may be equal to the number of gamma voltage offsets. The number of reference gamma voltage offsets may be less than the number of reference gamma voltages.

[0022] According to an exemplary embodiment of the present invention, the offset setter may generate the gamma voltage offsets by interpolating the reference gamma voltage offsets.

[0023] The source driver and the display device according to the exemplary embodiment of the present invention change the gamma voltage according to the change of the driving frequency, and thus can maintain the optical characteristics constant.

[0024] In addition, the source driver and the display device may each store a reference gamma voltage offset corresponding to a portion of the entire set of gray values, calculate a gamma voltage offset for the entire set of gray values ​​by interpolating the reference gamma voltage offset, and generate a gamma voltage corresponding to a variable frequency by adding the gamma voltage offset to a gamma voltage corresponding to a reference frequency. Since only the reference gamma voltage offset is set and stored, the manufacturing cost of the source driver and the display device may be reduced.

[0025] The display device includes a display unit having a plurality of pixels. A scan driver is configured to generate a scan signal for the display unit. A data driver is configured to generate a data signal for the display unit. The data driver includes a driving frequency determination circuit, a gamma voltage generation circuit, and a data voltage generation circuit, the driving frequency determination circuit is configured to determine a driving frequency for the display unit, the gamma voltage generation circuit is configured to generate a gamma voltage depending on the determined driving frequency for the display unit, and the data voltage generation circuit is configured to generate a data signal based on the generated gamma voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] A more complete understanding of the present disclosure and many of its attendant aspects will be readily obtained and become better understood by referring to the following detailed description when considered in conjunction with the accompanying drawings, in which:

[0027] Figure 1 is a block diagram showing a display device according to an exemplary embodiment of the present invention;

[0028] Figure 2 It is shown that the Figure 1 A block diagram of an example of a data driver in a display device;

[0029] Figure 3 It is shown that the Figure 2 A block diagram of an example of a gamma voltage generating circuit in a data driver;

[0030] Figure 4 is a diagram showing an example of a gamma voltage for each gray scale;

[0031] Figure 5 is a graph showing a difference between a gamma voltage according to a reference frequency and a gamma voltage according to a variable frequency;

[0032] Figure 6 It is shown Figure 3 A block diagram of an example of a gamma voltage generating circuit;

[0033] Figure 7 is shown by including Figure 6 FIG. 1 is a diagram showing an example of a gamma voltage offset set by an offset setter in a gamma voltage generating circuit of FIG. 1 ;

[0034] Figure 8 It is shown that the Figure 2 A block diagram of another example of a gamma voltage generating circuit in a data driver of FIG.

[0035] Fig. 9 It shows Figure 1 A sequence diagram of an example of an optical compensation method in which a display device performs optical compensation. DETAILED DESCRIPTION

[0036] Various exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that those skilled in the art can easily perform the present invention. The present invention can be implemented in many different forms and is not limited to the exemplary embodiments described herein.

[0037] In the drawings and their description, the same or similar reference numerals may be used to describe the same or similar elements. In addition, to the extent that detailed description of various elements is omitted, it can be assumed that those elements not described in detail are at least similar to corresponding elements described in detail elsewhere in the present disclosure and the drawings.

[0038] Figure 1 is a diagram illustrating a display device according to an exemplary embodiment of the present invention.

[0039] Reference Figure 1 The display device 100 includes a display unit 110 , a scan driver 120 (also referred to as a gate driver), a data driver 130 (also referred to as a source driver), and a timing controller 140 .

[0040] The display unit 110 (also referred to as a display panel) may include scan lines SL1 to SLn (where n is a positive integer), data lines DL1 to DLm (where m is a positive integer), and pixels PX. The pixels PX may be arranged in a region (eg, a pixel region) divided by the scan lines SL1 to SLn and the data lines DL1 to DLm.

[0041] Each of the pixels PX may be connected to one of the scan lines SL1 to SLn and one of the data lines DL1 to DLm. For example, the illustrated pixel PX may be connected to a scan line SLi and a data line DLj (where each of i and j is a specific positive integer). Although only one of the pixels PX is illustrated, it should be understood that there is one pixel PX for each possible combination of the scan lines SL1 to SLn and the data lines DL1 to DLm.

[0042] The pixel PX may emit light having brightness corresponding to a data signal supplied through the data line DLj in response to a scan signal supplied through the scan line SLi.

[0043] The scan driver 120 generates a scan signal in response to the scan control signal SCS, and sequentially supplies the scan signal to the scan lines SL1 to SLn. Here, the scan control signal SCS includes a start signal, a clock signal, etc., and may be provided from the timing controller 140. For example, the scan driver 120 may include a shift register that sequentially generates and outputs a pulse-shaped scan signal corresponding to the pulse-shaped start signal in response to the clock signal.

[0044] The data driver 130 may generate a data signal in response to the image data DATA2 and the data control signal DCS provided from the timing controller 140, and output the data signal to the display unit 110 (or the pixel PX). Here, the data control signal DCS controls the operation of the data driver 130, and may include a load signal (or a data enable signal) for instructing to output a valid data signal.

[0045] In an exemplary embodiment of the present invention, the data driver 130 may generate a gamma voltage corresponding to each possible value of the entire set of grayscale values, and may convert the image data DATA2 into an analog data signal using the gamma voltage.

[0046] In an exemplary embodiment of the present invention, the data driver 130 may change the driving frequency based on the control of the external input signal or the image data DATA2, and may change the gamma voltage based on the driving frequency. Here, the driving frequency is the frequency at which the data driver 130 is driven, and may be the same as the frequency of the output data signal. For example, the data driver 130 may change the driving frequency from a base frequency of 60 Hz to 48 Hz, 85 Hz, 120 Hz, etc., and may adjust the gamma voltage according to the changed driving frequency.

[0047] The following will refer to Figure 2 and Figure 3 A description is given of a configuration in which the data driver 130 changes the gamma voltage according to a change in the driving frequency.

[0048] The timing controller 140 may receive input image data DATA1 and a control signal CS from an external source (e.g., a graphics processor), generate a scan control signal SCS and a data control signal DCS in response to the control signal CS, and convert the input image data DATA1 to generate image data DATA2. For example, the timing controller 140 may convert the input image data DATA1, which may be in an RGB format, into image data DATA2, which may be in an RGBG format, to conform to a pixel arrangement in the display unit 110.

[0049] The display unit 110 may receive a first power voltage VDD and a second power voltage VSS which are voltages necessary for the operation of the pixel PX and may have a higher voltage level than that of the second power voltage VSS.

[0050] At least one of the scan driver 120, the data driver 130, and the timing controller 140 may be a part of the display unit 110, or may be configured as an integrated circuit (IC) to be connected to the display unit 110 through a tape carrier package. In addition, at least two of the scan driver 120, the data driver 130, and the timing controller 140 may be configured as a single IC.

[0051] Figure 2 It is shown that the Figure 1 A block diagram of an example of a data driver in a display device.

[0052] Reference Figure 1 and Figure 2 , the data driver 130 may include a driving frequency determination circuit 210 , a gamma voltage generation circuit 220 , and a data voltage generation circuit 230 .

[0053] The driving frequency determination circuit 210 may determine the driving frequency FREQ of the data driver 130. For example, the driving frequency determination circuit 210 may determine or change the driving frequency FREQ in response to an external input (e.g., a signal provided from the timing controller 140 and indicating that the driving frequency FREQ is changed). For example, the driving frequency determination circuit 210 may change the driving frequency FREQ based on a transmission period of the image data DATA2. According to an exemplary embodiment of the present invention, the driving frequency determination circuit 210 may be omitted, and the driving frequency FREQ may be provided from an external source (e.g., the timing controller 140).

[0054] The gamma voltage generating circuit 220 may generate a gamma voltage GVS, and may change the gamma voltage GVS based on the driving frequency FREQ. Here, the gamma voltage GVS corresponds to each possible value of the entire set of grayscale values, and for example, 256 gamma voltages GVS corresponding to grayscale values ​​of 0 to 255 may be generated. In addition, the gamma voltage generating circuit 220 may generate a gamma voltage GVS for each sub-pixel. Here, the sub-pixel may be included in one pixel and emit monochromatic light. For example, the sub-pixel may be a red sub-pixel emitting red light, a green sub-pixel emitting green light, or a blue sub-pixel emitting blue light.

[0055] The data voltage generating circuit 230 may generate the data voltage V_DATA based on the gamma voltage GVS and the image data DATA2. For example, the data voltage generating circuit 230 may include a shift register for transmitting the image data DATA2, a data latch for latching the data received from the shift register, a digital-to-analog converter (DAC) for converting the digital data transmitted through the data latch into an analog data signal based on the gamma voltage, a buffer for outputting the data signal to an external source, etc.

[0056] Figure 3 It is shown that the Figure 2 A block diagram of an example of a gamma voltage generating circuit in a data driver of FIG.

[0057] Reference Figure 2 and Figure 3 , the gamma voltage generating circuit 220 may include a memory 310, a first gamma voltage generator 320, an offset setter 330, and a second gamma voltage generator 340. In addition, the gamma voltage generating circuit 220 may further include a selector 350. Each of these elements may be implemented as a circuit, and two or more of these elements may be implemented on a single circuit.

[0058] The memory 310 (or storage device) may store information about a reference gamma voltage RGVS1 (or a representative gamma voltage) of a reference frequency and information about a reference gamma voltage offset RGVOS1 (or a reference gamma voltage offset value, a representative gamma voltage offset) of each of possible driving frequencies (hereinafter referred to as "variable frequencies") different from the reference frequency. Here, the reference frequency may be a common (or standard) driving frequency of the display device 100, for example, 60 Hz, and is not limited thereto. When the data driver 130 is driven at the reference frequency, the reference gamma voltage RGVS1 of the reference frequency is a part of the first gamma voltage GVS1 generated by the gamma voltage generating circuit 220, and, for example, the reference gamma voltage RGVS1 may be 10 gamma voltages selected from 256 first gamma voltages GVS1. For example, the number of the reference gamma voltages RGVS1 may be less than the number of the first gamma voltages GVS1. The information about the reference gamma voltages RGVS1 may include a value indicating a voltage level of each of the reference gamma voltages RGVS1 or a selection value for selecting the reference gamma voltage RGVS1 from among a plurality of preset voltages.

[0059] Similarly, the variable frequency (or changed frequency) FREQ may be a frequency different from the reference frequency, such as 48 Hz, 85 Hz, and 120 Hz. The reference gamma voltage offset RGVOS1 of the variable frequency FREQ may be a value set for a portion of the second gamma voltage GVS2 of the variable frequency FREQ based on a portion of the reference gamma voltage RGVS1 of the reference frequency. For example, the reference gamma voltage offset RGVOS1 of the variable frequency FREQ may be a voltage difference (e.g., 4 voltage differences) between 4 gamma voltages selected from 256 second gamma voltages GVS2 and the reference gamma voltage corresponding thereto (e.g., 4 gamma voltages selected from 10 reference gamma voltages RGVS1). For example, the number of reference gamma voltage offsets RGVOS1 may be less than the number of second gamma voltages GVS2, and may be less than the number of reference gamma voltages RGVS1 of the reference frequency. As described below, as the number of reference gamma voltage offsets RGVOS1 becomes smaller, the capacity of the memory 310 is reduced, and the number / required time (or takt time) of optical compensation steps required for setting the reference gamma voltage offset RGVOS1 in the manufacturing steps is reduced, and therefore, the cost of the data driver 130 (and the display device 100) can be reduced.

[0060] The information about the reference gamma voltage offset RGVOS1 may have the same form as the information about the reference gamma voltage RGVS1 of the reference frequency.

[0061] The first gamma voltage generator 320 may generate the first gamma voltage GVS1 based on the reference gamma voltage RGVS1 set corresponding to the reference frequency. For example, the first gamma voltage generator 320 may generate 10 reference gamma voltages RGVS1 based on information about the 10 reference gamma voltages RGVS1, and generate 256 first gamma voltages GVS1 by dividing the 10 reference gamma voltages RGVS1. The first gamma voltage generator 320 is configured by a universal gamma voltage generator, and may include, for example, at least one resistor string connected between a maximum reference voltage and a minimum reference voltage, and a plurality of selectors (e.g., multiplexers) that select a portion of the voltage divided by the at least one resistor string.

[0062] The offset setter 330 (or offset generator, offset calculator) may generate the gamma voltage offset GVOS2 based on the reference gamma voltage offset RGVOS1 set corresponding to the variable frequency FREQ. Here, the variable frequency FREQ (or information about the variable frequency FREQ) may be provided from the driving frequency determination circuit 210. For example, the offset setter 330 may interpolate 4 reference gamma voltage offsets RGVOS1 to generate 256 gamma voltage offsets GVOS2.

[0063] The second gamma voltage generator 340 may generate the second gamma voltage GVS2 based on the first gamma voltage GVS1 and the gamma voltage offset GVOS2. For example, the second gamma voltage generator 340 may add 256 first gamma voltages GVS1 and 256 gamma voltage offsets GVOS2 to generate 256 second gamma voltages GVS2, respectively.

[0064] The selector 350 may output the first gamma voltage GVS1 or the second gamma voltage GVS2. For example, the selector 350 may output the second gamma voltage GVS2 preferentially, and may output the first gamma voltage GVS1 when the second gamma voltage GVS2 is not applied.

[0065] As reference Figure 3 As described, the gamma voltage generating circuit 220 can generate the second gamma voltage GVS2 of the variable frequency FREQ based on the reference gamma voltage offset RGVOS1 set corresponding to the variable frequency FREQ and the first gamma voltage GVS1 of the reference frequency. Since the number of the reference gamma voltage offset RGVOS1 is less than the number of the reference gamma voltage RGVS1 of the reference frequency, the number of times / required time for optical compensation for setting the reference gamma voltage offset RGVOS1 in the manufacturing step (or the tact time required for correcting the brightness / color coordinates) is reduced, and therefore, the cost of the data driver 130 (and the display device 100) can be reduced.

[0066] Figure 4 is a diagram showing an example of a gamma voltage for each grayscale.

[0067] First, refer to Figure 4 , a first frequency red gamma curve 60Hz_RED, a first frequency green gamma curve 60Hz_GREEN, a first frequency blue gamma curve 60Hz_BLUE, a second frequency red gamma curve 85Hz_RED, a second frequency green gamma curve 85Hz_GREEN, and a second frequency blue gamma curve 85Hz_BLUE are shown.

[0068] When the data driver 130 (see Figure 1 ) is driven at a first driving frequency (or reference frequency) of 60 Hz, the first frequency red gamma curve 60 Hz_RED, the first frequency green gamma curve 60 Hz_GREEN, and the first frequency blue gamma curve 60 Hz_BLUE represent the gamma characteristics of the red sub-pixel, the gamma characteristics of the green sub-pixel, and the gamma characteristics of the blue sub-pixel, respectively. Similarly, when the data driver 130 (see Figure 1) is driven with a second driving frequency of 85 Hz (or variable frequency FREQ), the second frequency red gamma curve 85Hz_RED, the second frequency green gamma curve 85Hz_GREEN and the second frequency blue gamma curve 85Hz_BLUE respectively represent the gamma characteristics of the red sub-pixel, the gamma characteristics of the green sub-pixel and the gamma characteristics of the blue sub-pixel.

[0069] Table 1 shows the relationship between the gamma voltage according to the reference frequency and the gamma voltage according to the variable frequency FREQ as follows.

[0070] Table 1:

[0071]

[0072] Refer to Table 1, according to Figure 4 The first frequency red gamma curve 60Hz_RED, the first frequency green gamma curve 60Hz_GREEN, the first frequency blue gamma curve 60Hz_BLUE, the second frequency red gamma curve 85Hz_RED, the second frequency green gamma curve 85Hz_GREEN, and the second frequency blue gamma curve 85Hz_BLUE shown in FIG. 1 show data voltages of representative gray values, for example, reference gamma voltages. Here, the representative gray values ​​correspond to characteristic points (for example, inflection points) on the first frequency red gamma curve 60Hz_RED, the first frequency green gamma curve 60Hz_GREEN, the first frequency blue gamma curve 60Hz_BLUE, the second frequency red gamma curve 85Hz_RED, the second frequency green gamma curve 85Hz_GREEN, and the second frequency blue gamma curve 85Hz_BLUE. For example, the representative grayscale values ​​may include grayscale values ​​of 11, 23, 35, 51, 87, 151, 203, and 255 among grayscale values ​​of 0 to 255, but these grayscale values ​​are examples and the representative grayscale values ​​are not limited thereto.

[0073] On the first frequency red gamma curve 60Hz_RED, the first frequency green gamma curve 60Hz_GREEN, the first frequency blue gamma curve 60Hz_BLUE, the second frequency red gamma curve 85Hz_RED, the second frequency green gamma curve 85Hz_GREEN and the second frequency blue gamma curve 85Hz_BLUE, as the grayscale increases, the data voltage V_DATA decreases, and this exemplifies the sub-pixel (or Figure 1 The pixel PX) includes a p-type transistor, and the present invention is not limited thereto.

[0074] like Figure 4As shown in Table 1, the first frequency red gamma curve 60Hz_RED, the first frequency green gamma curve 60Hz_GREEN, and the first frequency blue gamma curve 60Hz_BLUE may have data voltages different from each other for one grayscale (or the same grayscale). Accordingly, a reference voltage is set for each sub-pixel. Figure 3 The reference gamma voltage RGVS1 is described, and the first gamma voltage GVS1 may be generated for each sub-pixel.

[0075] Similarly, the second frequency red gamma curve 85 Hz_RED, the second frequency green gamma curve 85 Hz_GREEN, and the second frequency blue gamma curve 85 Hz_BLUE have data voltages different from each other for one gray scale (or the same gray scale).

[0076] The first frequency red gamma curve 60 Hz_RED and the second frequency red gamma curve 85 Hz_RED may have data voltages different from each other for one grayscale (or the same grayscale) even if the curves have gamma characteristics for the same red sub-pixel. Accordingly, in order to drive the variable frequency FREQ of the display device 100, the first gamma voltage GVS1 corresponding to the first frequency red gamma curve 60 Hz_RED separately requires the second gamma voltage GVS2 corresponding to the second frequency red gamma curve 85 Hz_RED (and a setting value for generating the second gamma voltage GVS2).

[0077] Since the relationship between the first frequency green gamma curve 60 Hz_GREEN and the second frequency green gamma curve 85 Hz_GREEN and the relationship between the first frequency blue gamma curve 60 Hz_BLUE and the second frequency blue gamma curve 85 Hz_BLUE are substantially the same or similar to the relationship between the first frequency red gamma curve 60 Hz_RED and the second frequency red gamma curve 85 Hz_RED, repeated description will not be repeated.

[0078] When the data voltage RV_DATA (or the reference gamma voltage) on the second frequency red gamma curve 85Hz_RED or the setting value corresponding thereto is fully stored, referring to Figure 3 The capacity of the described memory 310 increases, and a process (or a required time for the process, a tact time) for measuring or setting the data voltage RV_DATA on the second frequency red gamma curve 85 Hz_RED may increase.

[0079] Accordingly, the data driver 130 (or the display device 100) may store only the voltage difference (delta) between the data voltage RV_DATA on the first frequency red gamma curve 60 Hz_RED (e.g., the reference gamma voltage RGVS1) and the data voltage RV_DATA on the second frequency red gamma curve 85 Hz_RED (e.g., the voltage difference (delta) set for each representative gray), and the capacity of the memory 310 may be reduced.

[0080] In addition, the data driver 130 (or the display device 100) selects only a portion of the voltage difference (delta) to determine as a reference. Figure 3 The reference gamma voltage offset RGVOS1 described above (e.g., the reference gamma voltage offset RGVOS1 of the variable frequency FREQ of 85 Hz). For example, only the voltage differences (delta) corresponding to the gray values ​​of 11, 23, 51, and 255 may be included in the reference gamma voltage offset RGVOS1. The capacity of the memory 310 may be further reduced. In addition, during the optical compensation process, only the data voltage of a portion of the representative gray value corresponding to the reference gamma voltage offset RGVOS1 is measured instead of the entire representative gray value, and therefore, the takt time may be further reduced.

[0081] Described in this article Figure 5 The reference gamma voltage offset RGVOS1 and a portion of a representative grayscale value corresponding to the reference gamma voltage offset RGVOS1 are shown.

[0082] Figure 5 is a graph showing a difference between a gamma voltage according to a reference frequency and a gamma voltage according to a variable frequency. Figure 5 A red delta curve delta_RED, a green delta curve delta_GREEN, and a blue delta curve delta_BLUE are shown for a variable frequency FREQ (e.g., a driving frequency of 85 Hz). Each of the red delta curve delta_RED, the green delta curve delta_GREEN, and the blue delta curve delta_BLUE may include a voltage difference (e.g., the voltage difference described with reference to Table 1) within the entire grayscale range GREYSCALE. Since the red delta curve delta_RED, the green delta curve delta_GREEN, and the blue delta curve delta_BLUE have similar inflection point characteristics, the red delta curve delta_RED will be described as a representative of the red delta curve delta_RED, the green delta curve delta_GREEN, and the blue delta curve delta_BLUE.

[0083] On the red Δ curve delta_RED, the voltage difference (delta) (or voltage difference or slope) begins to increase significantly at the point corresponding to grayscale 11, the voltage difference (delta) is the highest at the point corresponding to grayscale 23 and then begins to decrease significantly, the voltage difference (delta) begins to gradually decrease at the point corresponding to grayscale 51, and the voltage difference (delta) is the lowest at the point corresponding to grayscale 255.

[0084] Accordingly, the inflection point of the red delta curve delta_RED may be set as the first color reference gamma voltage offset. The voltage difference (delta) at the remaining points except the inflection point on the red delta curve delta_RED may be calculated by interpolating the two reference gamma voltage offsets adjacent to the relevant point. Similarly, the inflection point of the green delta curve delta_GREEN may be set as the second color reference gamma voltage offset, and the inflection point of the blue delta curve delta_BLUE may be set as the third color reference gamma voltage offset. The first color reference gamma voltage offset, the second color reference gamma voltage offset, and the third color reference gamma voltage offset may be included in the reference Figure 3 The reference gamma voltage is offset as described in RGVOS1.

[0085] Tables 2 and 3 herein show the effect of using the reference gamma voltage offset RGVOS1 instead of the reference gamma voltage.

[0086] Table 2:

[0087]

[0088] Table 3:

[0089]

[0090] Tables 2 and 3 show examples of tabulation points for setting the gamma voltages of Table 1. Tabulation points are grayscale points at which brightness is measured in an optical compensation process of the display device 100, and setting values ​​(or reference gamma voltages and voltage offsets) at tabulation points may be stored in the memory 310 (see Figure 3 )middle.

[0091] Referring to Table 2 and Table 3, Table 2 is a first lookup table and Table 3 is a second lookup table, and the first lookup table and the second lookup table include tabulation points at a first driving frequency (or a reference frequency, for example, 60 Hz) and tabulation points at a second driving frequency (or a first variable frequency, for example, 48 Hz).

[0092] The first lookup table may include a first tabulation point (e.g., grayscale value) to be compensated or measured for each brightness value DRV of the display device 100. For example, in order for the display device 100 driven at the second driving frequency of 85 Hz to display an image of 300 nits, data voltages of grayscale values ​​of 1, 7, 11, 23, 35, 51, 87, 151, 203, and 255 may be measured or compensated, for example, a total of 10 grayscale values ​​may be measured or compensated. When the display device 100 is optically compensated by using the first lookup table, the tact time for optical compensation may increase in proportion to the number of variable frequencies FREQ.

[0093] The second lookup table may include a second tabulation point (e.g., grayscale value) to be compensated or measured for each brightness value DRV of the display device 100. For example, in order for the display device 100 driven at the second driving frequency of 85 Hz to display an image of 300 nits, data voltages of grayscale values ​​of 11, 23, 51, and 255 may be measured or compensated, for example, a total of 4 grayscale values ​​may be measured or compensated. When optical compensation of the display device 100 is performed by using the second lookup table, the tact time for optical compensation may be reduced to 70% of the tact time of optical compensation using the first lookup table, and as the number of variable frequencies FREQ increases, the tact time for optical compensation may be smaller to be less than or equal to half of the tact time of optical compensation using the first lookup table.

[0094] In addition, the reference gamma voltage RGVS1 corresponding to the second lookup table (see Figure 3 ) and the reference gamma voltage offset RGVOS1 (see Figure 3 ) of the information storage 310 (see Figure 3 ) may be smaller so as to be less than or equal to half the capacity of the memory corresponding to the first lookup table.

[0095] As reference Figure 4 and Figure 5 As described in Tables 1 to 3, the gamma voltage is generated by using a reference gamma voltage offset of a portion of the representative grayscale value, and thereby the setting values ​​stored for generating the gamma voltage (e.g., the reference gamma voltage and the reference gamma voltage offset) can be reduced, and the beat time for optical compensation can be reduced.

[0096] Figure 6 It is shown Figure 3 1 is a block diagram of an example of a gamma voltage generating circuit.

[0097] Reference Figure 3 and Figure 6, the memory 310 may store information about the reference gamma voltage RGVS1 of the reference frequency and information about the reference gamma voltage offset RGVOS1 of the variable frequency FREQ. For example, the information about the reference gamma voltage RGVS1 of the reference frequency of 60 Hz may include a setting value W255OC of gray 255, a setting value W203OC of gray 203, a setting value W151OC of gray 151, a setting value W87OC of gray 87, a setting value W51OC of gray 51, a setting value W35OC of gray 35, a setting value W23OC of gray 23, a setting value W11OC of gray 11, a setting value W7OC of gray 7, and a setting value W1OC of gray 1. For example, information about the reference gamma voltage offset RGVOS1 for the variable frequency FREQ of 48 Hz may include a setting value W255OC of grayscale 255, a setting value W87OC of grayscale 87, a setting value W23OC of grayscale 23, and a setting value W7OC of grayscale 7.

[0098] The first gamma voltage generator 320 may include a first frequency gamma voltage setting unit 321 , a first frequency gamma voltage generating unit 322 , and a first frequency gamma voltage output unit 323 .

[0099] The first frequency gamma voltage setting unit 321 may generate the reference gamma voltage RGVS1 based on the information about the reference gamma voltage RGVS1. For example, the first frequency gamma voltage setting unit 321 may generate the reference gamma voltage RGVS1 by dividing the maximum reference voltage and the minimum reference voltage based on the information about the reference gamma voltage RGVS1.

[0100] The first frequency gamma voltage generating unit 322 may generate the first gamma voltage GVS1 based on the reference gamma voltage RGVS1. For example, the first frequency gamma voltage generating unit 322 may generate the first gamma voltage GVS1 of the entire set of gray values ​​by dividing the reference gamma voltage RGVS1.

[0101] The first frequency gamma voltage output unit 323 may provide the first gamma voltage GVS1 to the selector 350 or the data voltage generating circuit 230 (see Figure 2 ).

[0102] The offset setter 330 may include a second frequency data voltage offset selecting unit 331 , a second frequency data voltage offset setting unit 332 , and a second frequency offset voltage generating unit 333 .

[0103] The second frequency data voltage offset selection unit 331 may acquire information about the reference gamma voltage offset RGVOS1 based on the variable frequency FREQ.

[0104] According to an exemplary embodiment of the present invention, the second frequency data voltage offset selection unit 331 (or the offset setter 330) may determine a first adjacent frequency and a second adjacent frequency adjacent to a specific driving frequency, and set a reference gamma voltage offset corresponding to the specific driving frequency by interpolating a preset first adjacent reference gamma voltage offset corresponding to the first adjacent frequency and a preset second adjacent reference gamma voltage offset corresponding to the second adjacent frequency. Here, the first adjacent reference gamma voltage offset corresponding to the first adjacent frequency and the second adjacent reference gamma voltage offset corresponding to the second adjacent frequency may be stored in the memory 310, and the reference gamma voltage offset corresponding to the specific driving frequency may not be stored in the memory 310.

[0105] Please refer to Figure 7 A description will be given of a configuration in which a reference gamma voltage offset is set by using a first adjacent frequency and a second adjacent frequency.

[0106] Figure 7 is shown by including Figure 6 FIG. 1 is a diagram of an example of a gamma voltage offset value set by an offset value setter in a gamma voltage generating circuit of FIG.

[0107] Reference Figure 7 , when the reference gamma voltage offset RGVOS1 of the kth driving frequency Fk (where k is a positive integer) is not stored in the memory 310, the second frequency data voltage offset selection unit 331 (or the offset setter 330) may determine a first adjacent frequency F1 and a second adjacent frequency F2 adjacent to the kth driving frequency Fk, and may set the reference gamma voltage offset by interpolating a preset first adjacent reference gamma voltage offset RGVOS_A1 corresponding to the first adjacent frequency F1 and a preset second adjacent reference gamma voltage offset RGVOS_A2 corresponding to the second adjacent frequency F2. For example, the first reference gamma voltage offset RGVO_Fk of the kth driving frequency Fk may be determined based on the kth driving frequency Fk by interpolating a first reference gamma voltage offset RGVO1_F1 included in the first adjacent reference gamma voltage offset RGVOS_A1 and a first reference gamma voltage offset RGVO1_F2 included in the second adjacent reference gamma voltage offset RGVOS_A2. Accordingly, it is possible to reduce the capacity of the memory 310 , the tact time, the cost of the data driver 130 (and the display device 100 ), and the like.

[0108] Refer again Figure 6 , the second frequency data voltage offset setting unit 332 may generate the reference gamma voltage offset RGVOS1 based on the information about the reference gamma voltage offset RGVOS1.

[0109] The second frequency offset voltage generating unit 333 may generate the gamma voltage offset GVOS2 based on the reference gamma voltage offset RGVOS1. For example, the second frequency offset voltage generating unit 333 may generate the gamma voltage offset GVOS2 of the entire set of gray values ​​by dividing the reference gamma voltage offset RGVOS1.

[0110] The second gamma voltage generator 340 may include a second frequency gamma voltage generating unit 341 and a second frequency gamma voltage output unit 342 .

[0111] The second frequency gamma voltage generating unit 341 may generate the second gamma voltage GVS2 based on the first gamma voltage GVS1 and the gamma voltage offset GVOS2. For example, the second frequency gamma voltage generating unit 341 may generate the second gamma voltage GVS2 by adding the first gamma voltage GVS1 and the gamma voltage offset GVOS2.

[0112] The second frequency gamma voltage output unit 342 may provide the second gamma voltage GVS2 to the selector 350 or the data voltage generating circuit 230 (see Figure 2 ).

[0113] As reference Figure 6 and Figure 7 As described, the gamma voltage generating circuit 220 can calculate the reference gamma voltage offset corresponding to a specific driving frequency by interpolating the reference gamma voltage offsets set corresponding to adjacent frequencies. Accordingly, the capacity of the memory 310, the tact time, the cost of the data driver 130 (and the display device 100), etc. can be reduced.

[0114] Figure 8 It is shown that the Figure 2 FIG. 1 is a block diagram of another example of a gamma voltage generating circuit in a data driver of FIG. 1 .

[0115] Reference Figure 2 , Figure 3 and Figure 8 The gamma voltage generating circuit 220 may include a memory 910 (or a storage unit), an offset setter 920, a gamma voltage control signal generator 930, and a gamma voltage generator 940. The memory 910, the offset setter 920, and the gamma voltage generator 940 may be respectively connected to the reference Figure 3 The described memory 310 , the offset setter 330 , and the first gamma voltage generator 320 are substantially the same or similar, and thus, duplicate descriptions will not be repeated.

[0116] The offset setter 920 may generate a second reference gamma voltage offset RGVOS2 based on the first reference gamma voltage offset RGVOS1 set corresponding to the variable frequency FREQ. Figure 3 The reference gamma voltage offset RGVOS1 described above is substantially the same and may include, for example, an offset of 4 representative gray values ​​selected from among 10 representative gray values. The second reference gamma voltage offset RGVOS2 may include an offset corresponding to the first reference gamma voltage RGVS1 (eg, referring to Figure 3 The reference gamma voltage RGVS1 described above may include, for example, offsets of 10 representative gray values.

[0117] For example, the offset setter 920 may generate the second reference gamma voltage offset RGVOS2 by interpolating or extrapolating the first reference gamma voltage offset RGVOS1 based on the representative grayscale value.

[0118] The gamma voltage control signal generator 930 may generate a setting value (or a control signal) of the second reference gamma voltage RGVS2 corresponding to the variable frequency FREQ based on the second reference gamma voltage offset RGVOS2 and the first reference gamma voltage RGVS1 corresponding to the reference frequency (or a setting value of the first reference gamma voltage RGVS1 ).

[0119] For example, the gamma voltage control signal generator 930 may generate the setting values ​​of the second reference gamma voltage RGVS2 by adding the second reference gamma voltage offset RGVOS2 to the setting values ​​of the first reference gamma voltage RGVS1 , respectively.

[0120] The gamma voltage generator 940 may generate the gamma voltages GVS of the entire set of gray values ​​(or the gamma voltages corresponding to the variable frequency FREQ) based on the set value of the second reference gamma voltage RGVS2.

[0121] For example, refer to Figure 3 The gamma voltage generating circuit 220 described above may generate the first gamma voltage GVS1 and the second gamma voltage GVS2 by using the first gamma voltage generator 320 and the second gamma voltage generator 340, and Figure 8 The gamma voltage generating circuit shown in FIG. 9 may generate the gamma voltages GVS by using one gamma voltage generator 940 .

[0122] Fig. 9 It shows Figure 1 A sequence diagram of an example of an optical compensation method in which a display device performs optical compensation.

[0123] Reference Figure 1 , Figure 2 , Figure 3 and Fig. 9 ,exist Fig. 9 In the method of , the optical compensation value may be calculated based on a tabulation point at a first driving frequency (eg, 60 Hz) included in a second lookup table ( S1010 ).

[0124] For example, in Fig. 9 In the method, an image may be displayed for each grayscale value (or brightness) by the display device 100, the brightness of at least one area of ​​the display device 100 may be measured by the image capture device, and the data voltage may be adjusted so that the brightness / color coordinates are consistent with the reference brightness / reference color coordinates. The adjusted data voltage (e.g., the first data voltage) may be stored in the memory 310 as the reference gamma voltage RGVS1.

[0125] Later, in Fig. 9 In the method of , the optical compensation value may be calculated based on a tabulation point at a second driving frequency (eg, 48 Hz) included in a second lookup table (S1020).

[0126] For example, in Fig. 9 In the method, the second data voltage corresponding to the four representative gray values ​​may be set by displaying an image of each of the four representative gray values ​​by the display device 100.

[0127] Later, in Fig. 9 In the method, the first reference gamma voltage offset RGVOS1 may be calculated based on the second data voltage and a portion of the first data voltage corresponding to the second data voltage (eg, the first data voltage corresponding to a representative grayscale value for obtaining the second data voltage) (S1030).

[0128] For example, in Fig. 9 In the method, each of the voltage differences between the four second data voltages and the four data voltages selected from among the first data voltages may be calculated, and the voltage difference may be determined as the first reference gamma voltage offset RGVOS1. The first reference gamma voltage offset RGVOS1 may be stored in the memory 310.

[0129] According to an exemplary embodiment of the present invention, Fig. 9 In the method, a gamma voltage offset of the entire set of gray values ​​or a second reference gamma voltage offset RGVOS2 of a representative gray value may be calculated based on the first reference gamma voltage offset RGVOS1 ( S1040 ).

[0130] For example, in Fig. 9 In the method of , 255 gamma voltage offsets GVOS2 of the entire set of grayscale values ​​can be calculated by interpolating or extrapolating the four first reference gamma voltage offsets RGVOS1. Fig. 9In the method of , 10 second reference gamma voltage offsets RGVOS2 may be calculated by interpolating or extrapolating the four first reference gamma voltage offsets RGVOS1. In this case, the 10 second reference gamma voltage offsets RGVOS2 may be stored in the memory 310.

[0131] According to an exemplary embodiment of the present invention, Fig. 9 In the method, a first gamma voltage GVS1 of a first driving frequency may be generated based on a reference gamma voltage RGVS1, and a second gamma voltage GVS2 of a second driving frequency may be generated based on the first gamma voltage GVS1 and a gamma voltage offset GVOS2 (S1050).

[0132] For example, in Fig. 9 In the method of , the first gamma voltages may be generated by dividing the reference gamma voltage RGVS1 corresponding to the driving frequency of 60 Hz, and the second gamma voltages GVS2 may be generated by respectively adding the first gamma voltages GVS1 and the gamma voltage offsets GVOS2.

[0133] Later, in Fig. 9 In the method, one of the first gamma voltage GVS1 and the second gamma voltage GVS2 may be output (S1060).

[0134] As reference Fig. 9 As described, in the optical compensation method, optical compensation is performed only on a portion of representative grayscale values ​​of the display device 100 driven at the second driving frequency (or variable frequency FREQ), and thus the takt time can be reduced.

[0135] The detailed description and corresponding drawings provided above are exemplary only and various modifications and equivalents are within the scope of the present invention.

Claims

1. A source driver for a display device, comprising: a gamma voltage generating circuit configured to generate a gamma voltage, wherein the gamma voltage generating circuit is further configured to change the gamma voltage according to a driving frequency of the display device, including shifting a first gamma voltage corresponding to a first driving frequency to obtain a second gamma voltage corresponding to a second driving frequency; and a data voltage generating circuit configured to generate a data voltage for displaying image data on the display device based on the gamma voltage, Wherein, the gamma voltage generating circuit comprises: a first gamma voltage generator configured to generate a first gamma voltage based on a reference gamma voltage corresponding to a reference frequency; an offset setter configured to generate a gamma voltage offset based on a reference gamma voltage offset corresponding to the driving frequency of the display device; and a second gamma voltage generator configured to generate a second gamma voltage based on the first gamma voltage and the gamma voltage offset, wherein the number of the reference gamma voltage offsets is smaller than the number of the gamma voltage offsets, wherein the number of the second gamma voltages is equal to the number of the gamma voltage offsets, and The number of the reference gamma voltage offsets is smaller than the number of the reference gamma voltages.

2. The source driver for a display device according to claim 1, further comprising: A frequency determination circuit is configured to determine the driving frequency of the display device based on the image data.

3. The source driver for a display device according to claim 1, wherein: The offset setter is further configured to generate the gamma voltage offsets by interpolating the reference gamma voltage offsets.

4. The source driver for a display device according to claim 1, wherein: The offset setter is further configured to determine a first adjacent frequency and a second adjacent frequency adjacent to the driving frequency, and to set the reference gamma voltage offset by interpolating a preset first adjacent reference gamma offset corresponding to the first adjacent frequency and a preset second adjacent reference gamma offset corresponding to the second adjacent frequency.

5. The source driver for a display device according to claim 1, wherein: The reference gamma voltage offsets include a first color reference gamma voltage offset, a second color reference gamma voltage offset, and a third color reference gamma voltage offset.

6. The source driver for a display device according to claim 1, wherein: The reference gamma voltage offset is an inflection point of a curve configured by the gamma voltage offset.

7. The source driver for a display device according to claim 1, wherein: The gamma voltage generating circuit further includes: A storage device is configured to store information about the reference gamma voltage and information about the reference gamma voltage offset.

8. A source driver for a display device, comprising: a gamma voltage generating circuit configured to generate a gamma voltage, wherein the gamma voltage generating circuit is further configured to change the gamma voltage according to a driving frequency of the display device, including shifting a first gamma voltage corresponding to a first driving frequency to obtain a second gamma voltage corresponding to a second driving frequency; and a data voltage generating circuit configured to generate a data voltage for displaying image data on the display device based on the gamma voltage, Wherein, the gamma voltage generating circuit comprises: an offset setter configured to generate a second reference gamma voltage offset based on a first reference gamma voltage offset corresponding to the driving frequency; a gamma voltage control signal generator configured to set a second reference gamma voltage based on a preset first reference gamma voltage and the second reference gamma voltage offset; and a gamma voltage generator configured to generate a second gamma voltage based on the second reference gamma voltage, wherein the number of the first reference gamma voltage offsets is less than the number of the second reference gamma voltage offsets, wherein the number of the first reference gamma voltages is equal to the number of the second reference gamma voltage offsets, wherein the offset setter is configured to generate the second reference gamma voltage offset by interpolating the first reference gamma voltage offset, and The gamma voltage control signal generator is configured to generate the second reference gamma voltage by adding the first reference gamma voltage and the second reference gamma voltage offset respectively. 9 . A display device comprising the source driver for a display device according to claim 1 .

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