Digital gamma circuit and source driver including the same

Abstract

A digital gamma circuit capable of reducing chip area and adjusting the white coordinates is disclosed, along with a source driver including the digital gamma circuit. The digital gamma circuit may include a digital gamma algorithm for setting a gamma curve for each R, G, or B. Using the digital gamma algorithm, the value of an X-axis point of the gamma curve can be set, the value of a Y-axis point corresponding to the X-axis point value can be set, and the value of at least one Y-axis point indicating white can be adjusted by adding an offset value.

Description

Technical Field

[0001] This disclosure relates to a display device, and more specifically, to a digital gamma circuit having a function for adjusting a white chromatic coordinate and a source driver including therein. Prior Technology

[0002] Typically, a display device may include a display panel, a display driver, a timing controller, etc.

[0003] Display driving devices may include source drivers, and multiple source drivers may be included by taking into account the size and resolution of the display panel. Source drivers can convert image data into source signals using gamma voltage and can provide these source signals to the display panel.

[0004] The source driver may include digital gamma circuitry to generate data for selecting voltages corresponding to gray levels within a grayscale voltage range. In this case, the gray level refers to the brightness level of the screen.

[0005] The human eye is sensitive to dark gray levels but not to bright gray levels. Digital gamma circuits can support the selection of gamma voltage, so that the brightness of each gray level is perceived by the human eye at uniform intervals.

[0006] Ideally, the digital gamma circuit is configured to select the gamma voltage corresponding to each gray level, but due to the limitations of chip size, it is difficult to implement the above configuration for the digital gamma circuit.

[0007] Digital gamma circuits based on conventional technology do not have the function of adjusting the white color coordinate. Summary of the Invention

[0008] Various implementations are intended to provide digital gamma circuits that can reduce wafer area and adjust the white coordinates, as well as source drivers that include digital gamma circuits.

[0009] In an implementation, the digital gamma circuit may include a digital gamma algorithm for setting a gamma curve for each R, G, or B. Using the digital gamma algorithm, the value of the X-axis point of the gamma curve can be set, the value of the Y-axis point corresponding to the X-axis point can be set, and the value of at least one Y-axis point (indicating white) can be adjusted by adding an offset value to it.

[0010] In this implementation, the values ​​of the X-axis points of the gamma curve can be set at intervals of 2 squared.

[0011] In an implementation, the source driver may include: a digital gamma circuit configured to set a gamma curve for each R, G, or B, and to convert the input grayscale signal into data indicating luminance values ​​using the gamma curve; a gamma voltage generator configured to generate and provide a gamma voltage; and a gamma decoder configured to receive the gamma voltage and data, and to select and output the gamma voltage corresponding to the data. The digital gamma circuit can set the value of the X-axis point of the gamma curve, can set the value of the Y-axis point of the gamma curve corresponding to the X-axis point value, and can adjust the value of at least one Y-axis point indicating white by adding an offset value to it.

[0012] The digital gamma circuit disclosed herein can adjust the white coordinate by adding an offset value to the value of at least one Y-axis point indicating white in the value of the Y-axis point of the gamma curve.

[0013] Furthermore, the digital gamma circuit disclosed herein can reduce logic power and chip area by setting the value of the X-axis point of the gamma curve at intervals of 2 squared through shift operations in digital design without using a divider.

[0014] When the power consumption and wafer area of ​​the logic of the digital gamma circuit are reduced as described above, the source driver of the digital gamma circuit according to this disclosure can also reduce power consumption and can have a reduced wafer area. Simple Explanation of the Diagram

[0015] Figure 1 is a block diagram illustrating a source driver according to an embodiment of the present invention.

[0016] Figure 2 is a block diagram of the digital gamma circuit in Figure 1.

[0017] Figure 3 is a circuit diagram used to describe the adjustment of the white coordinates of a digital gamma circuit.

[0018] Figure 4 is a graph showing the gamma curve set by the digital gamma circuit. Implementation

[0019] This disclosure discloses a digital gamma circuit capable of reducing wafer area and adjusting the white coordinate, as well as a source driver including the digital gamma circuit.

[0020] In an implementation, the grayscale signal GRAY can be defined as a signal indicating the level of brightness of the screen. For example, the grayscale signal can indicate the brightness of the screen within a grayscale range of 0 to 255 levels (i.e., grayscale levels) and can be recorded as 12-bit data.

[0021] In an implementation, the gamma curve can be defined as indicating the correlation between the grayscale signal and the brightness of the image displayed on the display panel.

[0022] In the implementation, the X-axis point of the gamma curve can indicate the grayscale signal, the Y-axis point of the gamma curve can indicate the luminance, and the slope can indicate the gamma value.

[0023] In an implementation, the gamma value can indicate the ratio of the change in luminance to the change in screen brightness.

[0024] In an implementation, the command signal CMD can be defined as a signal provided from the outside to adjust the white coordinate relative to various color standards.

[0025] In describing the implementation methods, detailed descriptions of well-known technologies in the art will be omitted to avoid obscuring the subject matter of this disclosure.

[0026] Figure 1 is a block diagram of a source driver 100 including a digital gamma circuit 10 according to an embodiment.

[0027] Referring to Figure 1, the source driver 100 may include a digital gamma circuit 10, a gamma voltage generator 20, a gamma decoder (DEC) 30, and an output buffer 40.

[0028] The digital gamma circuit 10 can set a gamma curve for each red (R), green (G), or blue (B) color.

[0029] The digital gamma circuit 10 can set the value of the X-axis point of the gamma curve and the value of the Y-axis point corresponding to the X-axis point of the gamma curve.

[0030] In this configuration, the digital gamma circuit 10 can set the X-axis point values ​​at intervals of 2 squared. Limiting the interval of the X-axis point values ​​to 2 squared allows for the use of shift operations instead of dividers during linear interpolation in digital designs. This results in advantages such as reduced logic power and chip area for the digital gamma circuit 10.

[0031] Furthermore, the digital gamma circuit 10 can adjust the white coordinate by adding an offset value of each R, G, or B to the value of at least one Y-axis point indicating white. For example, the digital gamma circuit 10 can adjust the white coordinate by adding different offset values ​​to the values ​​of two or more Y-axis points indicating white. As another example, when setting which Y-axis point is the white point, the digital gamma circuit 10 can adjust the white coordinate by adding the same offset value to the value of Y-axis points after the white point.

[0032] Offset values ​​can be set relative to each of various color standards. Examples of color standards include Adobe RGB, standard RGB (sRGB), Digital Cinema Initiatives (DCI)-P3, etc. For each color standard, the X and Y coordinates of R, G, B, and W can be different, and other offset values ​​can be applied to the color standard.

[0033] The digital gamma circuit 10 can receive a command signal CMD for adjusting the white color coordinates, and can adjust the white color coordinates using an offset value relative to the color standard setting corresponding to the command signal CMD. For example, under normal conditions, the digital gamma circuit 10 can support only the 2.2 gamma curve or color coordinates of sRGB without needing to adjust the color coordinates separately.

[0034] When a command signal CMD is received from an application (not shown) instructing the white coordinate to be adjusted to the DCI-P3 coordinate, the digital gamma circuit 10 can adjust the white coordinate by applying an offset value corresponding to the DCI-P3 coordinate. For example, when a smartphone user is watching a movie, the application can provide the digital gamma circuit 10 of the source driver 100 with the command signal CMD instructing the white coordinate to be adjusted to the DCI-P3 coordinate.

[0035] When the application receives a command signal CMD instructing the white coordinates to be adjusted to the Adobe RGB coordinates, the digital gamma circuit 10 can adjust the white coordinates by applying an offset value corresponding to the Adobe RGB coordinates. For example, when a smartphone user wants to view a photo or attempts to watch a screen with vibrant colors, the application can provide the digital gamma circuit 10 of the source driver 100 with a command signal CMD instructing the white coordinates to be adjusted to the Adobe RGB coordinates.

[0036] For example, when a command signal CMD is received, offset values ​​for various color standards can be received from a controller (not shown) or an application. In another example, the offset values ​​for various color standards can be stored in memory (not shown). The offset values ​​in memory corresponding to the command signal CMD can be applied to adjust the white coordinates. The memory can be configured internally or externally to the source driver 100.

[0037] In addition, the digital gamma circuit 10 can receive the grayscale signal GRAY and convert the grayscale signal GRAY into data DATA indicating the brightness value by using a gamma curve.

[0038] In this configuration, the digital gamma circuit 10 can select the values ​​of two X-axis points, including the grayscale signal GRAY, between the X-axis points. Furthermore, the digital gamma circuit 10 can select the values ​​of two Y-axis points adjacent to the grayscale signal GRAY and corresponding to the values ​​of the two X-axis points.

[0039] As described above, the digital gamma circuit 10 can use the values ​​of two selected X-axis points and two Y-axis points as described above to calculate the luminance value corresponding to the grayscale signal GRAY by linear interpolation.

[0040] The digital gamma circuit 10 can convert the 12-bit grayscale signal GRAY into 10-bit data DATA indicating the brightness value, and can provide the data DATA to the gamma decoder 30.

[0041] The gamma voltage generator 20 can generate 1024 gamma voltages and provide 1024 gamma voltages to the gamma decoder 30.

[0042] The gamma decoder 30 can receive gamma voltage from the gamma voltage generator 20, receive data DATA indicating brightness values ​​from the digital gamma circuit 10, and can select the gamma voltage corresponding to the data DATA. That is, the gamma decoder 30 can select the gamma voltage corresponding to the brightness of the screen and can provide the selected gamma voltage to the output buffer 40.

[0043] The output buffer 40 can output the gamma voltage provided by the gamma decoder 30 to the display panel (not shown). That is, the output buffer 40 can output the gamma voltage of the 256-grayscale image corresponding to the grayscale signal GRAY with 256 grayscale levels to the display panel.

[0044] The digital gamma circuit 10 can set a gamma curve for each R, G or B, and can adjust the white coordinate by adding an offset value corresponding to the color standard to the value of at least one Y-axis point (i.e., the final Y-axis point) corresponding to white in the value of the Y-axis point of the gamma curve.

[0045] Figure 2 is a block diagram of the digital gamma circuit 10 according to an embodiment.

[0046] Referring to Figure 2, the digital gamma circuit 10 may include a digital gamma algorithm. The digital gamma algorithm can be represented as having multiple functional blocks. The multiple functional blocks can be represented as including an X-point generation unit 11, a Y-point set linear interpolation unit 12, a Y-point offset unit 13, an XY-point selection unit 14, a linear interpolation unit 15, and a color mixing unit 16.

[0047] The digital gamma circuit 10 can be configured to set a gamma curve for each R, G, or B using a digital gamma algorithm. For example, the digital gamma circuit 10 can generate a gamma curve by using up to 25 points on each of the X and Y axes.

[0048] In addition to the grayscale signal GRAY and command signal CMD described with reference to Figure 1, the digital gamma circuit 10 can also receive the point values ​​on the X-axis, the point values ​​on the Y-axis, brightness information, and offset values. The point values ​​on the X-axis are indicated as points 0 to 24. The point values ​​on the Y-axis are indicated as SET0-Ypoint 0 to 24, SET1-Ypoint 0 to 24, and SET2-Ypoint 0 to 24. The brightness information is indicated as BI. The point values ​​on the X-axis, the point values ​​on the Y-axis, the brightness information, and the offset values ​​can be understood from the description given below.

[0049] The digital gamma circuit 10 can receive point values ​​from 0 to 24 and generate the values ​​of the X-axis points of the gamma curve. The values ​​of the X-axis points of the gamma curve can be generated by the X-point generation unit 11. The X-point generation unit 11 can generate X-axis point values ​​(refer to Figure 4) from Xpoint0 to Xpoint24 at intervals of 2 squared based on point values ​​from 0 to 24.

[0050] For example, when receiving 0 as the point value (point value = point 0), the X-point generation unit 11 can set the value Xpoint0 of X-axis point0 to 0. Furthermore, when receiving 1 as the point value (point value = point 1), the X-point generation unit 11 can set the value Xpoint1 of X-axis point1 to Xpoint0+21. Furthermore, when receiving 2 as the point value (point value = point 2), the X-point generation unit 11 can set the value Xpoint2 of X-axis point2 to Xpoint1+22.

[0051] In this way, the values ​​of X-axis points Xpoint0 to Xpoint24 can be set at intervals of 2 squared. The structure for setting the X-axis points from value Xpoint_0 to Xpoint_24 at intervals of 2 squared is such that, if the grayscale signal GRAY, indicating the brightness level, is used as the input value between the values ​​of the two X-axis points, the brightness is calculated by replacing the divider with a shift operation instead of using the divider when performing linear interpolation to calculate the corresponding luminance.

[0052] Furthermore, the digital gamma circuit 10 can set the values ​​of the Y-axis points corresponding to the X-axis points Xpoint0 to Xpoint24, which are set at intervals of 2 squared as described above, based on the target brightness.

[0053] For example, a set can be set to the Y-axis point values ​​Ypoint0 to Ypoint24. Depending on the target brightness of the panel, multiple such sets can be set. For example, the first set SET0 can be set to the Y-axis point values ​​indicating the highest brightness. The second set SET1 can be set to the Y-axis point values ​​indicating medium brightness. The third set SET2 can be set to the Y-axis point values ​​indicating the lowest brightness. For example, the Y-axis point values ​​of the first set SET0 can be indicated as SET0-Ypoint0 to 24, the Y-axis point values ​​of the second set SET1 can be indicated as SET1-Ypoint0 to 24, and the Y-axis point values ​​of the third set SET2 can be indicated as SET2-Ypoint0 to 24.

[0054] Furthermore, in order to indicate various types of brightness, the digital gamma circuit 10 can calculate the values ​​of Y-axis points between multiple sets by linear interpolation. The linear interpolation of the values ​​of Y-axis points between multiple sets can be performed by the Y-point set linear interpolation unit 12.

[0055] For example, when receiving brightness information BI of the target brightness from the indicator panel, the Y-point set linear interpolation unit 12 of the digital gamma circuit 10 can select the set corresponding to the brightness information BI, or it can calculate the Y-axis point values ​​Ypoint0 to Ypoint24 by linearly interpolating the values ​​of the Y-axis points between sets of brightness adjacent to the brightness corresponding to the brightness information BI. The brightness information BI can be received from the application and can be received in the form of binary data. For example, when receiving brightness information BI between the first set and the second set, the Y-point set linear interpolation unit 12 can calculate the Y-axis point values ​​Ypoint0 to Ypoint24 corresponding to the brightness information BI by using the Y-axis point values ​​SET0-Ypoint0 to 24 of the first set and the Y-axis point values ​​SET1-Ypoint0 to 24 of the second set.

[0056] In addition, the digital gamma circuit 10 can adjust the white color coordinate.

[0057] For example, the digital gamma circuit 10 can adjust the white coordinate by adding an offset value of each R, G, or B to the value of at least one Y-axis point indicating white from Ypoint0 to Ypoint24. The white coordinate can be adjusted by the Y-point offset unit 13.

[0058] For example, the Y-point offset unit 13 of the digital gamma circuit 10 can adjust the white coordinate by adding different offset values ​​or the same offset value to the values ​​of two or more Y-axis points indicating white.

[0059] The Y-point offset unit 13 of the digital gamma circuit 10 can be set with an offset value relative to each of various color standards. For example, the Y-point offset unit 13 can be set with an offset value for each R, G, or B relative to each of various color standards (such as Adobe RGB, sRGB, and DCI-P3).

[0060] The digital gamma circuit 10 can receive a command signal CMD for adjusting the white color coordinate. The Y-point offset unit 13 can adjust the white color coordinate using an offset value relative to the color standard set corresponding to the command signal CMD.

[0061] For example, when a user attempts to watch a movie, the application can provide the source driver 100 with a command signal CMD instructing the white coordinates to be adjusted to the DCI-P3 coordinates. Upon receiving the command signal CMD from the application, the digital gamma circuitry 10 of the source driver 100 can adjust the white coordinates of the gamma curve by applying an offset value corresponding to the DCI-P3 coordinates. In this case, although the white coordinates are adjusted, the 2.2 gamma curve still needs to be maintained.

[0062] Furthermore, when a user wants to view a photo or attempts to watch a screen with vibrant colors, the application can provide the source driver 100 with a command signal CMD instructing the white coordinate to be adjusted to the Adobe RGB coordinate. When the application receives the command signal CMD instructing the white coordinate to be adjusted to the Adobe RGB coordinate, the digital gamma circuit 10 of the source driver 100 can adjust the white coordinate by applying an offset value corresponding to the Adobe RGB coordinate.

[0063] The operation of adjusting the white coordinate using the offset value corresponding to the command signal CMD will be described later with reference to Figure 3.

[0064] The digital gamma circuit 10 of the source driver 100 can be designed to receive the offset value of the corresponding color standard when receiving the command signal CMD for adjusting the color coordinates. Alternatively, the digital gamma circuit 10 of the source driver 100 can be designed to retrieve the corresponding offset value from the memory storing the offset value of the corresponding color standard when receiving the command signal CMD for adjusting the color coordinates.

[0065] In addition, the digital gamma circuit 10 can receive a grayscale signal GRAY, which indicates the brightness level of the image to be displayed on the display panel, from the application, and can convert the grayscale signal GRAY into data DATA, which indicates the luminance value, by means of a set gamma curve.

[0066] For example, the digital gamma circuit 10 can locate the position of the received grayscale signal GRAY between X-axis points, and can select the values ​​of the two X-axis points required for linear interpolation. Furthermore, the digital gamma circuit 10 can select the values ​​of the two Y-axis points corresponding to the values ​​of the two X-axis points.

[0067] The values ​​of the two X-axis points and the two Y-axis points can be selected by the XY point selection unit 14. That is, the XY point selection unit 14 can select the values ​​of the two X-axis points adjacent to the grayscale signal GRAY, and can select the values ​​of the two Y-axis points corresponding to the values ​​of the two X-axis points.

[0068] Furthermore, the digital gamma circuit 10 can calculate the luminance value corresponding to the grayscale signal GRAY by using the values ​​of two X-axis points and two Y-axis points.

[0069] The linear interpolation unit 15 can use the values ​​of two X-axis points and two Y-axis points to calculate the luminance value corresponding to the grayscale signal GRAY. It can be understood that the linear interpolation unit 15 performs linear interpolation on the values ​​of the two X-axis points and the values ​​of the two Y-axis points in response to the grayscale signal GRAY. The linear interpolation unit 15 can output a grayscale signal GRAY with luminance values ​​calculated by multiple linear interpolations.

[0070] Digital gamma circuit 10 can convert the 12-bit grayscale signal GRAY output by linear interpolation unit 15 into 10-bit data DATA indicating luminance values ​​by using color mixing. Color mixing can be performed by color mixing unit 16. Color mixing can be defined as an image processing scheme used in the process of reducing the number of colors in an image. This color mixing enables the display of high-definition images by generating patterns using combinations of similar colors, so as to represent shadows or colors using a limited number of colors.

[0071] Color mixing can be categorized into temporal color mixing and spatial color mixing. Temporal color mixing allows for the representation of a large number of colors by combining consecutive frames over time using temporal averages. Spatial color mixing allows for the expansion of representable gray levels by using spatial averages.

[0072] The following effect can be expected: when the 12 bits corresponding to the value of the Y-axis point are provided as 10 bits of data to the gamma decoder 30 using such a color mixing function, the lower 2 bits of the decimal point can be represented.

[0073] For example, when V is selected by the gamma decoder 30 <0> voltage and V <1> When the voltages are 6V and 5V respectively, the voltage selected by the gamma decoder 30 is either 6V or 5V. However, due to the color mixing effect, it can exhibit voltage effects of 5.25V, 5.5V, or 5.75V. Therefore, the brightness can be finely adjusted.

[0074] Figure 3 is a circuit diagram illustrating the adjustment of the white coordinate by the Y-point offset unit 13 of the digital gamma circuit 10.

[0075] Referring to Figures 1 to 3, it can be understood that the values ​​of the X-axis point and the Y-axis point are ultimately set between the values ​​of the X-axis point and the Y-axis point corresponding to the white coordinates. In this case, it can be understood that the final set values ​​of the X-axis point and the Y-axis point are respectively the maximum values ​​of the X-axis point and the Y-axis point.

[0076] To adjust the white coordinates, the value of the Y-axis point corresponding to the white coordinates needs to be adjusted. Adjusting the corresponding R, G, and B offset values ​​is necessary because white is produced by the combination of R, G, and B.

[0077] Various panel manufacturers may each want to use a different number of X-axis points. Therefore, it is necessary to freely apply offsets to specify a range.

[0078] The offset values ​​for R, G, and B can be set relative to each of the various color standards.

[0079] The digital gamma circuit 10 can select the offset value OFFSET in response to the offset enable signal Offset_en provided in response to the command signal CMD, and can adjust the white coordinate by adding the offset value to the value Ypoint indicating the white Y-axis point.

[0080] Therefore, as shown in Figure 3, the Y-point offset unit 13 of the digital gamma circuit 10 can be configured to include a multiplexer 132 and an adder 134. In this case, the multiplexer 132 is configured to select and provide one of an offset value OFFSET and 0 in response to the offset enable signal Offset_en. The adder 134 is configured to output the final white coordinate Ypoint obtained by adding the offset value OFFSET or 0 provided by the multiplexer 132 to the value Ypoint indicating the white of the Y-axis point.

[0081] For example, when receiving the command signal CMD corresponding to the sRGB color coordinates, the digital gamma circuit 10 can support only the 2.2 gamma curve or the sRGB color coordinates without adjusting the color coordinates.

[0082] When the command signal CMD corresponding to the DCI-P3 color coordinate is received, the digital gamma circuit 10 can select the offset value OFFSET corresponding to the DCI-P3 color coordinate, and can adjust the final Y-axis point value Ypoint by adding the offset value OFFSET to the value Ypoint of the Y-axis point corresponding to white.

[0083] When receiving the command signal CMD corresponding to the Adobe RGB color coordinates, the digital gamma circuit 10 can select the offset value OFFSET corresponding to the Adobe RGB color coordinates, and can adjust the final Y-axis point value Ypoint by adding the offset value OFFSET to the value Ypoint of the Y-axis point corresponding to white.

[0084] In this case, the digital gamma circuit 10 can adjust the final Y-point value by applying different offset values ​​to the white indicator value of the Y-axis point, or it can adjust the final Y-point value by applying the same offset value to all Y-axis points after the white Y-axis point when receiving information indicating which Y-axis point corresponds to white.

[0085] Furthermore, when the value of the final X-axis point is less than the maximum value of the grayscale signal GRAY or when the value of the grayscale signal GRAY is between the value of the final X-axis point and the maximum value of the received grayscale signal GRAY, the digital gamma circuit 10 can set the final Y-axis point to the value corresponding to the value of the final X-axis point, thereby maintaining the value of the final Y-axis point.

[0086] Figure 4 is a graph showing the gamma curve set by the digital gamma circuit according to the embodiment.

[0087] Referring to Figure 4, the X-axis indicates the grayscale signal GRAY, which is the input to indicate the screen brightness, the Y-axis indicates the output luminance, and the slope of the gamma curve indicates the gamma value.

[0088] The digital gamma circuit 10 can set the values ​​of X-axis points at intervals of 2 squared. For example, the value of X-axis point 0, Xpoint0, can be set to 0, the value of X-axis point 1, Xpoint1, can be set to Xpoint0+21, and the value of X-axis point 2, Xpoint2, can be set to Xpoint1+22. In this way, the values ​​of X-axis points can be set at intervals of 2 squared.

[0089] Depending on the target brightness, the digital gamma circuit 10 can freely set the value of the Y-axis point of the gamma curve, corresponding to the values ​​of the X-axis points set at intervals of 2 squared. For example, the values ​​of the Y-axis points can be set to multiple sets depending on the target brightness of the panel.

[0090] The digital gamma circuit 10 can calculate the luminance value corresponding to the grayscale signal GRAY by linear interpolation.

[0091] For example, when a grayscale signal GRAY with values ​​between Xpoint1 and Xpoint2 on the X-axis is input, the digital gamma circuit 10 can calculate the luminance value corresponding to the grayscale signal GRAY by using the values ​​Xpoint1 and Xpoint2 on the X-axis and the values ​​Ypoint1 and Ypoint2 on the Y-axis corresponding to the values ​​Xpoint1 and Xpoint2 on the X-axis.

[0092] The digital gamma circuit 10 can adjust the white color coordinate. For example, the digital gamma circuit 10 can adjust the value of the final Y-axis point by adding the offset value of each R, G, or B to the value of at least one Y-axis point indicating white.

[0093] For example, when the value of the white X-axis point is Xpoint22, the digital gamma circuit 10 can adjust the white coordinates by applying different offset values ​​offset22, offset23 and offset24 or the same offset value to the Y-axis point values ​​Ypoint22, Ypoint23 and Ypoint24 corresponding to the X-axis point values ​​Xpoint22, Xpoint23 and Xpoint24.

[0094] According to the embodiment, the digital gamma circuit can adjust the white coordinate by adding an offset value to the value of at least one Y-axis point indicating white in the value of the Y-axis point of the gamma curve.

[0095] Furthermore, digital gamma circuits can reduce chip area by setting the X-axis points of the gamma curve at intervals of 2 squared.

[0096] 10: Digital Gamma Circuit 11:X point generation unit 12: Linear interpolation unit of Y-point set 13: Y-point offset unit 14: XY point selection unit 15: Linear interpolation unit 16: Mixing unit 20: Gamma Voltage Generator 30: Gamma Decoder 40: Output buffer 100: Source Driver 132: Multiplexer 134: Adder B: Blue BI: Brightness Information CMD: Command signal DATA: Data DEC: Gamma Decoder G: Green GRAY: Grayscale signal OFFSET: Offset value Offset_en: Offset enable signal R: Red Xpoint0: Value Xpoint1: Value Xpoint2: Value Xpoint3: Value Xpoint22: value Xpoint23: Value Xpoint24: Value Ypoint: value Ypoint0: Value Ypoint1: Value Ypoint2: value Ypoint3: Value Ypoint22: value Ypoint23: value Ypoint24: value

Claims

1. A digital gamma circuit, comprising: A digital gamma algorithm is used to set a gamma curve for each red, green, or blue color. The algorithm sets the value of an X-axis point of the gamma curve, sets the value of a Y-axis point corresponding to the X-axis point, and adjusts the value of at least one Y-axis point indicating white by adding an offset value. The algorithm receives a grayscale signal, selects the values ​​of two adjacent X-axis points and two corresponding Y-axis points, and calculates a luminance value using the selected values ​​of the two X-axis points and the two selected Y-axis points.

2. The digital gamma circuit according to claim 1, wherein, The values ​​of the X-axis points are set at intervals of 2 squared.

3. The digital gamma circuit according to claim 1, wherein, The digital gamma algorithm adjusts the values ​​of two or more Y-axis points that indicate white, as another offset value.

4. The digital gamma circuit according to claim 1, wherein, When setting which of the Y-axis points is the white point, the digital gamma algorithm adjusts the value of the Y-axis points after the white point based on the same offset value.

5. The digital gamma circuit according to claim 1, wherein, The offset value is set differently relative to each of the various color standards.

6. The digital gamma circuit according to claim 5, wherein, When a command signal for adjusting the white coordinate is received, the digital gamma algorithm adjusts the value of the at least one Y-axis point corresponding to the white based on an offset value set for the color standard corresponding to the command signal.

7. The digital gamma circuit according to claim 1, wherein, The digital gamma algorithm converts a 12-bit grayscale signal into 10-bit data.

8. The digital gamma circuit according to claim 1, wherein: The value of the Y-axis point is set to a plurality of sets depending on the target brightness of the panel, and when brightness information is received from the application, the digital gamma algorithm selects the set corresponding to the brightness information or calculates the value of the Y-axis point between the plurality of sets by linear interpolation.

9. The digital gamma circuit according to claim 1, wherein: The digital gamma circuit includes an X-point generation unit, a Y-point set linear interpolation unit, a Y-point offset unit, an XY-point selection unit, a linear interpolation unit, and a color mixing unit for the digital gamma algorithm. The X-point generation unit receives the values ​​of the X-axis points and generates the values ​​of the X-axis points of the gamma curve at intervals of 2 squared. The Y-point set linear interpolation unit receives luminance information and the values ​​of first Y-axis points from multiple sets, and calculates the values ​​of second Y-axis points by linearly interpolating the values ​​of the first Y-axis points between sets adjacent to the luminance information. The Y-point offset unit adjusts the value of at least one second Y-axis point corresponding to white based on an offset value set for a color standard in response to an external command signal. The XY point selection unit receives an external first grayscale signal and selects the values ​​of two X-axis points adjacent to the first grayscale signal and the values ​​of two second Y-axis points corresponding to the values ​​of the two X-axis points. The values ​​of the two X-axis points are selected from the values ​​of the X-axis points provided by the X-point generation unit, and the values ​​of the two second Y-axis points are selected from the values ​​of the Y-axis points provided by the Y-point offset unit. The linear interpolation unit receives the first grayscale signal and outputs a second grayscale signal having a luminance value calculated using the values ​​of the two X-axis points and the values ​​of the two second Y-axis points selected by the XY point selection unit. The color mixing unit converts the second grayscale signal having a first bit into data having a second bit and indicating the luminance value by color mixing, and outputs the data.

10. A source driver, comprising: A digital gamma circuit is configured to set a gamma curve for each red, green, or blue color, and to convert an input grayscale signal into data indicating a luminance value using the gamma curve; a gamma voltage generator is configured to generate and provide a gamma voltage; and a gamma decoder is configured to receive the gamma voltage and the data and to select and output a gamma voltage corresponding to the data, wherein the digital gamma circuit sets the value of an X-axis point of the gamma curve, sets the value of a Y-axis point of the gamma curve corresponding to the value of the X-axis point, and adjusts the value of at least one Y-axis point by adding an offset value to the value of at least one Y-axis point indicating white; wherein the digital gamma circuit receives a grayscale signal, selects the values ​​of two X-axis points adjacent to the grayscale signal and the values ​​of two Y-axis points corresponding to the values ​​of the two X-axis points, and calculates a luminance value using the selected values ​​of the two X-axis points and the selected values ​​of the two Y-axis points.

11. The source driver according to claim 10, wherein, The digital gamma circuit sets the values ​​of the X-axis points at intervals of 2 squared.

12. The source driver according to claim 10, wherein, The digital gamma circuit adjusts the values ​​of two or more Y-axis points that are indicated by white, as another offset value.

13. The source driver according to claim 10, wherein, When setting which of the Y-axis points is the white point, the digital gamma circuit adjusts the value of the Y-axis point after the white point based on the same offset value.

14. The source driver according to claim 10, wherein, The offset value is set differently relative to each of the various color standards.

15. The source driver according to claim 14, wherein, When a command signal for adjusting the white coordinate is received, the digital gamma circuit adjusts the value of the at least one Y-axis point corresponding to the white based on an offset value set for the color standard corresponding to the command signal.

16. The source driver according to claim 10, wherein, The digital gamma circuit converts the 12-bit grayscale signal into 10-bit data.

17. The source driver according to claim 10, wherein: The value of the Y-axis point is set to a plurality of sets depending on the target brightness of the panel, and when brightness information is received from the application, the digital gamma circuit selects the set corresponding to the brightness information or calculates the value of the Y-axis point between the plurality of sets by linear interpolation.

18. The source driver according to claim 10, wherein: The digital gamma circuit includes an X-point generation unit, a Y-point set linear interpolation unit, a Y-point offset unit, an XY-point selection unit, a linear interpolation unit, and a color mixing unit. The X-point generation unit receives the values ​​of the X-axis points and generates the X-axis point values ​​of the gamma curve at intervals of 2 squared. The Y-point set linear interpolation unit receives luminance information and the values ​​of multiple sets of first Y-axis points, and calculates the values ​​of second Y-axis points by linearly interpolating the values ​​of the first Y-axis points between sets adjacent to the luminance information. The Y-point offset unit adjusts the value of at least one second Y-axis point corresponding to white based on an offset value set for a color standard in response to an external command signal. The XY point selection unit receives an external first grayscale signal and selects the values ​​of two X-axis points adjacent to the first grayscale signal and the values ​​of two second Y-axis points corresponding to the values ​​of the two X-axis points. The values ​​of the two X-axis points are selected from the values ​​of the X-axis points provided by the X-point generation unit, and the values ​​of the two second Y-axis points are selected from the values ​​of the Y-axis points provided by the Y-point offset unit. The linear interpolation unit receives the first grayscale signal and outputs a second grayscale signal having a luminance value calculated using the values ​​of the two X-axis points and the values ​​of the two second Y-axis points selected by the XY point selection unit. The color mixing unit converts the second grayscale signal having a first bit into data having a second bit and indicating the luminance value by color mixing, and outputs the data.

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