Display device

Abstract

A display device includes a display region including a plurality of pixels, a low gray scale dithering controller that selects a dithering gray scale in accordance with an input gray scale in a low gray scale range below a threshold gray scale in input image data, and generates dithered input image data by performing a dithering operation on the input image data in the low gray scale range based on the dithering gray scale, and a display driver that drives the plurality of pixels based on the dithered input image data.

Description

[0001] This application claims priority and benefit to Korean Patent Application No. 10-2020-0152944, filed on November 16, 2020, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] This disclosure relates to a display device, and more specifically, to a display device capable of dithering a displayed image. Background Technology

[0003] A display device uses pixels to display an image based on input image data received from an external device. The display device can process the input image data in various ways to improve display quality. For example, the display device can perform dithering to express additional grayscale and brightness using a limited grayscale level.

[0004] Display devices can improve their display quality by performing dithering on the displayed image. Summary of the Invention

[0005] This disclosure provides a display device capable of dithering a low-grayscale image by selecting a dithering grayscale based on an input grayscale value in a low grayscale range from the input image data.

[0006] Furthermore, this disclosure provides a method for driving a display device by performing a dithering operation.

[0007] However, this disclosure is not limited to the display device and the method of driving the display device described above, and various extensions can be made to the display device and the method of driving the display device disclosed herein without departing from the spirit and scope of this disclosure.

[0008] According to embodiments of the present disclosure, a display device may include: a display area including a plurality of pixels; a low grayscale dithering controller that selects a dithering grayscale based on an input grayscale in a low grayscale range below a threshold grayscale in the input image data, and generates dithered input image data by performing a dithering operation on the input image data in the low grayscale range based on the dithering grayscale; and a display driver that drives the plurality of pixels based on the dithered input image data.

[0009] According to an embodiment, the low-grayscale jitter controller may include a memory storing a lookup table, the lookup table including a plurality of reference grayscale values ​​corresponding to each input grayscale value within the low grayscale range. The low-grayscale jitter controller may, in response to an input grayscale value, select one of the plurality of reference grayscale values ​​as the jitter grayscale value.

[0010] According to the embodiment, multiple reference gray levels can be greater than the threshold gray level.

[0011] According to an embodiment, a low-grayscale dithering controller can perform dithering operations by expressing the input grayscale based on dithering grayscale and black grayscale.

[0012] According to an embodiment, for the same dithering grayscale, the ratio of the dithering grayscale applied in the low grayscale dithering region in the display area where the dithering operation is performed can increase as the input grayscale increases.

[0013] According to an embodiment, the low-grayscale jitter controller can select a first jitter grayscale in response to a first input grayscale, and can select a second jitter grayscale in response to a second input grayscale that is smaller than the first input grayscale. The second jitter grayscale can be greater than the first jitter grayscale.

[0014] According to an embodiment, the low grayscale jitter controller can select a first jitter grayscale in response to a third input grayscale that is less than the second input grayscale.

[0015] According to an embodiment, in the low grayscale jitter region of the display area, the second ratio for applying the second jitter grayscale may be different from at least one of the first ratio for applying the first jitter grayscale in response to the first input grayscale and the third ratio for applying the first jitter grayscale in response to the third input grayscale.

[0016] According to an embodiment, in a low grayscale jitter region, the second ratio of applying the second jitter grayscale can be less than or equal to the third ratio of applying the first jitter grayscale in response to the third input grayscale.

[0017] According to an embodiment, the display driver may include a data driver that supplies dithered grayscale data voltages and black data voltages for black grayscale to a plurality of pixels.

[0018] According to an embodiment, the second voltage deviation between the second data voltage of the second jittered grayscale and the black data voltage can be greater than the first voltage deviation between the first data voltage of the first jittered grayscale and the black data voltage.

[0019] According to an embodiment, the low grayscale range may include grayscale values ​​that are greater than black grayscale and equal to or lower than the threshold grayscale.

[0020] According to the embodiment, the black grayscale can be grayscale 0, the threshold grayscale can be grayscale 10 of eight-bit grayscale, and the reference grayscale can be grayscale 11 to grayscale 15 of eight-bit grayscale.

[0021] According to another embodiment of this disclosure, a method for driving a display device may include: setting a low grayscale jitter region in a display area based on input grayscale values ​​in input image data that are in a low grayscale range below a threshold grayscale; selecting one of a plurality of reference grayscale values ​​as the jitter grayscale value in response to the input grayscale values, wherein the plurality of reference grayscale values ​​may correspond to each input grayscale value in the low grayscale range; and performing image jittering in the low grayscale jitter region based on the jitter grayscale value and the black grayscale value.

[0022] According to an embodiment, for the same jitter grayscale, the method may further include increasing the ratio of applying jitter grayscale in the low grayscale jitter region as the input grayscale increases.

[0023] According to an embodiment, the method may further include selecting a first dithered grayscale in response to a first input grayscale, and selecting a second dithered grayscale in response to a second input grayscale that is smaller than the first input grayscale. The second dithered grayscale may be greater than the first dithered grayscale.

[0024] According to an embodiment, the method may further include selecting a first dithered gray level in response to a third input gray level that is less than the second input gray level.

[0025] According to an embodiment, in a low grayscale jitter region, the second ratio for applying the second jitter grayscale can be equal to or less than the third ratio for applying the first jitter grayscale in response to the third input grayscale.

[0026] According to an embodiment, the second voltage deviation between the second data voltage of the second dithered grayscale and the black data voltage of the black grayscale can be greater than the first voltage deviation between the first data voltage of the first dithered grayscale and the black data voltage.

[0027] According to an embodiment, the low grayscale range may include grayscale values ​​that are greater than black grayscale and equal to or lower than the threshold grayscale. Attached Figure Description

[0028] The accompanying drawings are included to provide a further understanding of the inventive concept, and are incorporated in and constitute a part of this disclosure. The drawings illustrate some embodiments of the inventive concept and, together with the detailed description, serve to explain the principles of the inventive concept.

[0029] Figure 1 This is a block diagram illustrating a display device according to an embodiment.

[0030] Figure 2 It is shown that it includes Figure 1 A diagram of a low grayscale dithering controller in a display device.

[0031] Figure 3 This is for explaining the embodiments. Figure 2 A diagram illustrating the operation of a low-grayscale jitter controller.

[0032] Figure 4 This is a diagram showing the jittered grayscale corresponding to the input grayscale according to an embodiment.

[0033] Figure 5A , Figure 5B and Figure 5C It shows Figure 2 A diagram illustrating an example of the operation of a low-grayscale jitter controller.

[0034] Figure 6 This is a graph illustrating an example of the relationship between jitter grayscale and data voltage.

[0035] Figure 7 This is a diagram showing the jittered grayscale corresponding to the input grayscale according to another embodiment.

[0036] Figure 8 It shows Figure 2 A diagram illustrating an example of the operation of a low-grayscale jitter controller.

[0037] Figure 9 This is a flowchart illustrating a method for driving a display device according to an embodiment. Detailed Implementation

[0038] Below, some embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used for the same parts, and repeated descriptions of the same parts are omitted.

[0039] Figure 1 This is a block diagram illustrating a display device 1000 according to an embodiment.

[0040] refer to Figure 1 The display device 1000 may include a display area 100, a display driver 200, and a low grayscale dithering controller 300.

[0041] The display device 1000 can be a flat panel display device, a flexible display device, a curved display device, a foldable display device, a bendable display device, or a stretchable display device. Furthermore, the display device 1000 can be applied to transparent display devices, head-mounted display devices, or wearable display devices. Additionally, the display device 1000 can be applied to various electronic devices, such as smartphones, tablet computers, smart tablets, televisions (TVs), or monitors.

[0042] The display device 1000 can be implemented as a self-emissive display device including multiple self-emissive elements. For example, the display device 1000 can be an organic light-emitting display device including organic light-emitting elements, a display device including inorganic light-emitting elements, or a display device including light-emitting elements comprising a combination of inorganic and organic materials. However, this is merely an example, and the display device 1000 can be implemented as a liquid crystal display device, a plasma display device, or a quantum dot display device, etc.

[0043] Display area 100 may include scan lines SL1 to SLn, data lines DL1 to DLm, and pixels PX, where n and m can be integers greater than 1. Pixels PX may be electrically connected to the data lines DL1 to DLm and the scan lines SL1 to SLn. According to an embodiment, at least one scan line may be connected to each of the pixels PX.

[0044] Each pixel PX can emit light with a brightness corresponding to the gray level supplied from the data lines DL1 to DLm.

[0045] The low-grayscale jitter controller 300 can select the jitter grayscale based on the grayscale (input grayscale) corresponding to the low grayscale range in the input image data IDATA. Multiple jitter grayscale values ​​can be stored in a lookup table, and the low-grayscale jitter controller 300 can select the jitter grayscale value from among these values ​​by searching the lookup table. The low grayscale range can include grayscale values ​​below a predetermined threshold grayscale. For example, the low grayscale range can include low grayscale values ​​that the light-emitting element cannot express using the drive current provided from the driving transistor of the pixel PX. When the grayscale of the input image data IDATA is expressed in 8 bits (i.e., 256 grayscale levels or 256 brightness levels), the threshold grayscale can be grayscale 10, and the low grayscale range can include grayscale values ​​from 1 to 10.

[0046] The low-grayscale dithering controller 300 can generate dithered input image data by performing a dithering operation on the low grayscale range of the input image data IDATA based on the dithered grayscale. The low-grayscale dithering controller 300 can provide the dithered input image data as first data DATA1 to the display driver 200. For example, the first data DATA1 can be image data corresponding to the low-grayscale dithering area of ​​the display area 100. Therefore, grayscale values ​​that are not expressed by the drive current in the low-grayscale dithering area can be output through the dithering operation. Here, grayscale 0 may be black grayscale, and dithering may not be applied to black grayscale values.

[0047] Dithering operations can be performed using various dithering methods. For example, spatial dithering and / or temporal dithering methods can be used to perform dithering operations on low grayscale ranges.

[0048] In an embodiment, the time-dithering method can widen the expression of grayscale range by changing the grayscale over time. For example, when grayscale 0 (or black grayscale) and dithered grayscale are displayed alternately according to frame and / or position, and the ratio of dithered grayscale changes within a predetermined area, the time-dithering method can express the low grayscale between grayscale 0 and dithered grayscale.

[0049] Display driver 200 can drive pixels PX based on input image data IDATA. In an embodiment, display driver 200 may include scan driver 220, data driver 240, and timing controller 260.

[0050] The timing controller 260 can receive input image data IDATA (e.g., red / green / blue (RGB) data) from an external device (e.g., a graphics processor) and first data DATA1 from a low-grayscale dithering controller 300. The timing controller 260 can generate a scan control signal SCS and a data control signal DCS based on the control signals received from the external device. Additionally, the timing controller 260 can rearrange the input image data IDATA and the first data DATA1 into second data DATA2 corresponding to the pixel arrangement of the display area 100, and output the second data DATA2 to the data driver 240.

[0051] The scan driver 220 can receive the scan control signal SCS from the timing controller 260 and supply scan signals to the scan lines SL1 to SLn accordingly. For example, the scan control signal SCS may include a start signal and a clock signal, etc.

[0052] The scan driver 220 may be disposed on the display area 100 (or an area of ​​the display panel), or it may be implemented as an integrated chip (IC) and mounted on a flexible circuit board to connect to the display area 100. In embodiments, the scan driver 220 may be located on opposite sides of the display area 100 (e.g., the left and right sides).

[0053] The data driver 240 can generate a data voltage based on the data control signal DCS and the second data DATA2, and provide the data voltage to the data lines DL1 to DLm. The data control signal DCS can control the operation of the data driver 240 and may include data enable signals, etc.

[0054] The data driver 240 can be implemented as an IC (e.g., a driver IC) and can be mounted on a flexible circuit board to connect to the display area 100.

[0055] Although Figure 1N scan lines, SL1 to SLn, are shown, but this disclosure is not limited thereto. As an example, corresponding to the circuit structure of pixel PX, a pixel PX connected to the scan line corresponding to the current horizontal line (or current pixel row) may be additionally connected to the scan line corresponding to the previous horizontal line (or previous pixel row) and / or the scan line corresponding to the next horizontal line (or next pixel row). Dummy scan lines (not shown) may be additionally formed in the display area 100. Furthermore, the display device 1000 may further include an emission driver (not shown) for controlling the emission of light from pixel PX.

[0056] exist Figure 1 In this disclosure, the low-grayscale jitter controller 300, the timing controller 260, and the data driver 240 are shown as separate elements, but this disclosure is not limited thereto. For example, at least some functions of the low-grayscale jitter controller 300 and / or the timing controller 260 may be implemented in the data driver 240, or the low-grayscale jitter controller 300 and / or the timing controller 260 may be included in the data driver 240.

[0057] Figure 2 It is shown that it includes Figure 1 A diagram of the low grayscale dithering controller 300 in the display device 1000. Figure 3 This is for explaining the embodiments. Figure 2 A diagram illustrating the operation of the low grayscale dithering controller 300.

[0058] refer to Figure 1 , Figure 2 and Figure 3 The low grayscale jitter controller 300 may include a jitter circuit 320 and a memory 340.

[0059] The dithering circuit 320 can analyze the input grayscale I_GRAY of the input image data IDATA to determine the low grayscale dithering region in the display area 100 where dithering is applied. For example, in the display area 100, the region where the input grayscale I_GRAY is applied below a threshold grayscale can be determined as the low grayscale dithering region.

[0060] Additionally, the dithering circuit 320 can select the dithered grayscale DG corresponding to the input grayscale I_GRAY of the input image data IDATA from the lookup table LUT stored in the memory 340.

[0061] In one embodiment, the lookup table (LUT) may include multiple reference grayscale values ​​(RG) corresponding to each of the input grayscale values ​​(I_GRAY) in the low grayscale range. For example, the low grayscale range of the lookup table LUT may include input grayscale values ​​1 to 10, excluding grayscale 0 (e.g., black grayscale BG). In another embodiment, the low grayscale range of the lookup table LUT may include a different number of input grayscale values ​​(e.g., more than 10 grayscale values). For example, the lookup table LUT may include input grayscale values ​​of grayscale values ​​11 to 15. Here, the reference grayscale values ​​(RG) may have grayscale values ​​greater than grayscale 10. For example, the reference grayscale values ​​(RG) may include grayscale values ​​of grayscale values ​​11 to 15.

[0062] In an embodiment, the dithering circuit 320 can achieve a brightness corresponding to the input grayscale I_GRAY based on the dithered grayscale DG and the black grayscale BG. For example, as Figure 3 As shown, the dithering circuit 320 can generate first data DATA1 corresponding to the dithering pattern included in the low grayscale dithering area LGDA of the display area 100. The dithering pattern can include information about the grayscale corresponding to each pixel in the pixels included in the low grayscale dithering area LGDA (e.g., the position of pixel PX with applied dithering grayscale DG and the position of pixel PX with applied black grayscale BG).

[0063] In an embodiment, the dithering pattern may have a form in which black grayscale BG and dithering grayscale DG are displayed alternately over time. For example, Figure 3 The diagram illustrates the digital representation of grayscale values ​​corresponding to a predetermined low-grayscale dithering region LGDA. A pixel PX with applied dithering grayscale DG can be represented as "1", and a pixel PX with applied black grayscale BG can be represented as "0". The dithering grayscale DG can be determined to be a grayscale 11 greater than the grayscale 10 corresponding to the threshold grayscale, and in response to the digital value 1, a data voltage of grayscale 11 can be supplied to the corresponding pixel PX.

[0064] Figure 3 The area of ​​the 2×2 dithering pattern is shown. In odd-numbered frames, the data voltage corresponding to the dithered grayscale DG can be supplied to the first pixel in the first row and first column, and the second pixel in the second row and second column; and in even-numbered frames, the data voltage corresponding to the dithered grayscale DG can be supplied to the third pixel in the first row and second column, and the fourth pixel in the second row and first column. Based on the input grayscale I_GRAY, such a dithering pattern can have a predetermined shape and / or sequence.

[0065] When the reference gray level RG used to represent gray levels in the low gray-level range is a single gray level, jitter noise may occur, reducing the expressiveness of a specific input gray level I_GRAY. In the displayed image, this jitter noise can be visually identified as mura.

[0066] The reference gray level RG can be experimentally calculated using image analysis, etc., through image capture. For example, in Figure 2 In the lookup table (LUT) shown, the reference gray level RG for the first gray level A can be set corresponding to the input gray level I_GRAY for gray levels 1, 2, 3, 4, 6, 7, 9, and 10. The reference gray level RG for the second gray level B can be set corresponding to the input gray level I_GRAY for gray level 5. The reference gray level RG for the third gray level C can be set corresponding to the input gray level I_GRAY for gray level 8.

[0067] The first grayscale A, the second grayscale B, and the third grayscale C can be greater than the threshold grayscale of the low grayscale range (e.g., grayscale 10). Furthermore, the sizes of the first grayscale A, the second grayscale B, and the third grayscale C can be independent of the size of the input grayscale I_GRAY. For example, the sizes of the second grayscale B and the third grayscale C can be greater than the size of the first grayscale A.

[0068] The dithering circuit 320 can select a reference grayscale RG corresponding to the input grayscale I_GRAY from a lookup table (LUT) as the dithering grayscale DG. As described above, the dithering circuit 320 can use a combination of the dithering grayscale DG and the black grayscale BG to perform time dithering in the low grayscale dithering region LGDA. For example, time dithering can be performed using a halftone method.

[0069] It should be noted that the dithering circuit 320 can perform dithering in various ways, not limited to the example above, and can also use dithering grayscale DG and black grayscale BG.

[0070] Figure 4 This is a diagram showing the jittered grayscale DG corresponding to the input grayscale I_GRAY according to an embodiment. Figures 5A to 5C It shows Figure 2 A diagram illustrating an example of the operation of the low grayscale jitter controller 300.

[0071] refer to Figure 1 , Figure 2 , Figure 4 , Figure 5A , Figure 5B and Figure 5C The low grayscale jitter controller 300 can determine the output grayscale O_GRAY by applying jitter in response to the input grayscale I_GRAY within the low grayscale range LGR.

[0072] In this embodiment, the low grayscale range LGR to which dithering is applied may include 10 grayscale levels from grayscale G1 to grayscale G10. Due to physical characteristics, a pixel PX may not be able to distinguish grayscale levels G1 to G10 from each other by controlling the drive current of the drive transistor, and therefore dithering can be used to represent the corresponding grayscale levels. In this example, grayscale G10 may be a threshold grayscale level that defines the low grayscale range LGR. In this case, grayscale 0 may be a black grayscale BG, and dithering may not be applied to the black grayscale BG.

[0073] The low-grayscale dithering controller 300 can represent the input grayscale I_GRAY using a pattern combination of dithered grayscale DG and black grayscale BG included in a predetermined mask pattern. The dithered grayscale DG can be greater than a threshold grayscale. For example, the dithered grayscale DG can have a grayscale value of G11 or higher.

[0074] The low-grayscale dithering controller 300 can select a dithering grayscale DG from multiple reference grayscale RGs by looking up a lookup table (LUT). For example, the reference grayscale RGs may include a first dithering grayscale DG1 and a second dithering grayscale DG2. Figure 4 As shown, the dithered grayscale DG can be selected as one of a first dithered grayscale DG1 corresponding to grayscale G11 and a second dithered grayscale DG2 corresponding to grayscale G13. The data voltage corresponding to the first dithered grayscale DG1 and the data voltage corresponding to the second dithered grayscale DG2 can be different from each other.

[0075] It should be noted that the gray values ​​of the first jitter grayscale DG1 and the second jitter grayscale DG2, as well as the number of jitter grayscale DG (i.e., the number of reference grayscale RG), are not limited to the examples above.

[0076] For example, when the input grayscale I_GRAY is grayscale G10, the first dithering grayscale DG1 and the black grayscale BG can be selected as the output grayscale O_GRAY. The low grayscale dithering controller 300 can output a dithering pattern that includes a combination of the first dithering grayscale DG1 and the black grayscale BG. Therefore, grayscale G10 can be represented.

[0077] When the input grayscale I_GRAY is grayscale G9, the low grayscale dithering controller 300 can output a dithering pattern that includes a combination of the first dithering grayscale DG1 and the black grayscale BG. Similarly, when the input grayscale I_GRAY is one of grayscale G1, grayscale G2, grayscale G3, grayscale G4, grayscale G6, grayscale G7, and grayscale G8, the low grayscale dithering controller 300 can output a dithering pattern that includes a combination of the first dithering grayscale DG1 and the black grayscale BG.

[0078] As described above, various low grayscale outputs can be achieved by combining the first dithering grayscale DG1 and the black grayscale BG. When the first dithering grayscale DG1 is applied for dithering, the ratio of applying the first dithering grayscale DG1 in the low grayscale dithering region LGDA of the display area 100 can increase as the input grayscale I_GRAY increases. This will be referenced... Figure 5A and Figure 5C Detailed description.

[0079] Figures 5A to 5C The display area 100 is shown as a low grayscale dithering region LGDA with a 4×4 pattern. The grayscale obtained through dithering can be displayed in the low grayscale dithering region LGDA. Here, the low grayscale dithering region LGDA can refer to the portion of the display area 100 where dithering is applied.

[0080] It should be noted that the following description is based on the assumption that the first input grayscale I_GRAY1 is greater than the second input grayscale I_GRAY2 and the second input grayscale I_GRAY2 is greater than the third input grayscale I_GRAY3. As a non-limiting example, the first input grayscale I_GRAY1 can be grayscale G6, the second input grayscale I_GRAY2 can be grayscale G5, and the third input grayscale I_GRAY3 can be grayscale G4.

[0081] In an embodiment, for a frame, the first dithered grayscale DG1 and the second dithered grayscale DG2 can be applied to a random position within the low grayscale dithering region LGDA or a predetermined dithering pattern. In this case, even if the positions where the first dithered grayscale DG1 and the second dithered grayscale DG2 are applied may change, the ratio of the dithered grayscale DG (e.g., the first dithered grayscale DG1 or the second dithered grayscale DG2) in the low grayscale dithering region LGDA can be kept constant at a value corresponding to the input grayscale I_GRAY.

[0082] like Figure 5A As shown, in response to the first input grayscale I_GRAY1, the first dithering grayscale DG1 can be applied to the low grayscale dithering region LGDA at a ratio of 9 / 16. Additionally, as... Figure 5C As shown, in response to the third input grayscale I_GRAY3, the first dithering grayscale DG1 can be applied to the low grayscale dithering region LGDA at a ratio of 6 / 16 (or 3 / 8).

[0083] As described above, when the low grayscale jitter controller 300 performs jitter operation based on the first jitter grayscale DG1, the ratio of the first jitter grayscale DG1 applied in the low grayscale jitter region LGDA of the display area 100 can increase as the input grayscale I_GRAY increases.

[0084] When the low-grayscale dithering controller 300 performs dithering based on the first dithering grayscale DG1 in response to the second input grayscale I_GRAY2, mura may be visually identifiable in the displayed image due to dithering noise. Therefore, for the second input grayscale I_GRAY2, the low-grayscale dithering controller 300 can use a second dithering grayscale DG2, which is different from the first dithering grayscale DG1, to perform dithering.

[0085] Therefore, the image can be displayed in the low grayscale jitter region LGDA with a grayscale (and its corresponding brightness) similar to the second input grayscale I_GRAY2. For example, as Figure 4 As shown, the image displayed based on the second dithered grayscale DG2 can have a grayscale corresponding to grayscale G5.

[0086] For example, such as Figure 5B As shown, in response to the second input grayscale I_GRAY2, the low grayscale jitter controller 300 can apply the second jitter grayscale DG2 to the low grayscale jitter region LGDA at a ratio of 6 / 16 (or 3 / 8). In this case, the second jitter grayscale DG2 can be greater than the first jitter grayscale DG1. In the embodiment, as... Figure 5B and Figure 5C As shown, the ratio of the second jittered grayscale DG2 corresponding to the second input grayscale I_GRAY2 in the low grayscale jitter region LGDA can be the same as the ratio of the first jittered grayscale DG1 corresponding to the third input grayscale I_GRAY3 in the low grayscale jitter region LGDA.

[0087] It should be noted that the ratio of the second jittered grayscale DG2 corresponding to the second input grayscale I_GRAY2 in the low grayscale jitter region LGDA can be less than the ratio of the first jittered grayscale DG1 corresponding to the third input grayscale I_GRAY3 in the low grayscale jitter region LGDA.

[0088] When the input grayscale I_GRAY is less than the third input grayscale I_GRAY3, the ratio of the first dithering grayscale DG1 applied to the dithering pattern can be less than [a certain value]. Figure 5B The ratio of the second dithered grayscale DG2 shown.

[0089] In other words, the ratio of the second jitter grayscale DG2 used to implement the second input grayscale I_GRAY2 in the low grayscale jitter region LGDA can be determined, regardless of the ratio of the first jitter grayscale DG1 used to implement the other input grayscale I_GRAY.

[0090] As described above, the display device 1000 can perform dithering on a low grayscale image based on a dithered grayscale DG selected from a plurality of reference grayscale RGs according to the input grayscale I_GRAY within the low grayscale range LGR. Therefore, the non-uniformity of color coordinates within the low grayscale range (e.g., grayscale 10 or less) and / or the mura caused by dithering noise in the low grayscale image can be minimized or eliminated, thereby improving the image quality of the display device 1000.

[0091] Figure 6 This is a graph illustrating an example of the relationship between jitter grayscale and data voltage.

[0092] refer to Figure 1 , Figure 2 , Figure 4 , Figure 5A , Figure 5B , Figure 5C and Figure 6 The magnitude of the data voltage can be determined based on the dithered grayscale (DG).

[0093] The data driver 240 included in the display driver 200 can convert the second data DATA2 into an analog format data voltage and supply the data voltage to the data lines DL1 to DLm.

[0094] In one embodiment, the data driver 240 may include a digital-to-analog (DA) converter that converts digitally formatted grayscale values ​​into data voltages. The data driver 240 may convert dithered grayscale values ​​(DG) into dithered data voltages and black grayscale values ​​(BG) into black data voltages (V_BK).

[0095] The data driver 240 can convert the first jittered grayscale DG1 into a first jittered data voltage V_DG1, and can convert the second jittered grayscale DG2 into a second jittered data voltage V_DG2.

[0096] To express the first input grayscale I_GRAY1, the data driver 240 can apply the first jitter data voltage V_DG1 and the black data voltage V_BK to the low grayscale jitter region LGDA.

[0097] To express the second input grayscale I_GRAY2, the data driver 240 can apply the second dithering data voltage V_DG2 and the black data voltage V_BK to the low grayscale dithering region LGDA.

[0098] Since the second jitter grayscale DG2 is greater than the first jitter grayscale DG1, the second voltage deviation Vdf2 (i.e., the voltage deviation between the second jitter data voltage V_DG2 and the black data voltage V_BK) can be greater than the first voltage deviation Vdf1 (i.e., the voltage deviation between the first jitter data voltage V_DG1 and the black data voltage V_BK).

[0099] That is, when an image with low grayscale within a low grayscale range (e.g., grayscale 10 or less) is expressed in the display area 100, the magnitude of the dithering data voltage can be changed according to the input grayscale I_GRAY.

[0100] As an example, Figure 6 The data voltage relationship of the P-type driving transistor (P-channel transistor) of pixel PX is shown. In this case, the first dithering data voltage V_DG1 and the second dithering data voltage V_DG2 can be less than the black data voltage V_BK.

[0101] When the driving transistor of pixel PX is an N-type (N-channel transistor), the first dithering data voltage V_DG1 and the second dithering data voltage V_DG2 can be greater than the black data voltage V_BK. Furthermore, the second dithering data voltage V_DG2 can be greater than the first dithering data voltage V_DG1. However, the relationship between the first voltage deviation Vdf1 and the second voltage deviation Vdf2 may be independent of the type of driving transistor, and the second voltage deviation Vdf2 can be greater than the first voltage deviation Vdf1.

[0102] As described above, the magnitude of the dithering data voltage supplied to the display area 100 can be varied based on the input grayscale I_GRAY within the low grayscale range LGR. Therefore, the non-uniformity of color coordinates within the low grayscale range (e.g., grayscale 10 or less) and / or the mura caused by dithering noise in the low grayscale image can be minimized or eliminated.

[0103] Figure 7 This is a diagram showing the jittered grayscale DG corresponding to the input grayscale I_GRAY according to another embodiment. Figure 8 It shows Figure 2 A diagram illustrating an example of the operation of the low grayscale jitter controller 300.

[0104] In addition to adding a third jitter grayscale DG3, the operation and reference of the low grayscale jitter controller 300 according to this embodiment are as follows: Figures 4 to 6 The operation of the low grayscale dithering controller 300 described is essentially the same. The same reference numerals are used for the same or corresponding parts, and repeated descriptions will be omitted.

[0105] refer to Figure 1 , Figure 2 , Figure 4 , Figure 5A , Figure 5B , Figure 5C and Figure 7 The low grayscale jitter controller 300 can determine the output grayscale O_GRAY by applying jitter in response to the input grayscale I_GRAY within the low grayscale range LGR.

[0106] In this embodiment, the low-grayscale dithering controller 300 can select a third dithering grayscale DG3 to represent the input grayscale I_GRAY of grayscale G3. For example, the third dithering grayscale DG3 can correspond to grayscale G12. Grayscale G3 can be most accurately represented by the dithering of grayscale G12 and black grayscale BG.

[0107] refer to Figure 8 In response to the fourth input grayscale I_GRAY4, the low grayscale jitter controller 300 can apply the third jitter grayscale DG3 to the low grayscale jitter region LGDA at a ratio of 4 / 16 (i.e., 1 / 4). The fourth input grayscale I_GRAY4 can correspond to grayscale G3.

[0108] The ratio at which the third dithering grayscale DG3 is applied to the low grayscale dithering region LGDA to display grayscale G3 can be set independently of the ratio at which the first dithering grayscale DG1 is applied to the same region to display grayscale G4 and the ratio at which the first dithering grayscale DG1 is applied to the same region to display grayscale G2.

[0109] As described above, by subdividing the dithered grayscale DG according to the input grayscale I_GRAY within the low grayscale range LGR, the quality of the low grayscale image displayed by the display device 1000 can be further improved.

[0110] Figure 9 This is a flowchart illustrating a method for driving a display device according to an embodiment.

[0111] refer to Figure 9 Drive the display device (e.g., Figure 1 The method of the display device 1000 may include: setting a low grayscale dithering region of the display area (S100); selecting one of the reference grayscales as the dithering grayscale in response to the input grayscale (S200); and dithering the image based on the dithering grayscale and the black grayscale (S300).

[0112] A low grayscale dithering region can be set in the display area (S100). For example, the input grayscale of the input image data supplied to the display device from an external device (e.g., a graphics processor) can be analyzed to determine the location or region with grayscale values ​​in a low grayscale range below a threshold grayscale value. The location or region in the display area with low input grayscale values ​​can be set as a low grayscale dithering region (S100).

[0113] The display device may include a lookup table storing a plurality of reference gray levels corresponding to each of the low input gray levels. Therefore, a reference gray level corresponding to the input gray level can be selected as the dithering gray level (S200).

[0114] Image dithering in low-grayscale dithering regions can be performed based on selected dithering grayscale and blackscale (S300). During image dithering, an image pattern combining the dithering grayscale and blackscale can be output to display an image of the input grayscale. According to one embodiment, a reference can be used... Figures 2 to 8 The described method for applying image jitter is used.

[0115] Already referenced Figures 2 to 8 A driving method for a display device that performs a dithering operation by selecting a dithering grayscale from multiple reference grayscales is described in detail. Therefore, repeated descriptions are omitted.

[0116] As described above, the display device and driving method of the present disclosure according to various embodiments can perform dithering of a low grayscale image using a dithered grayscale selected from a plurality of reference grayscales based on the input grayscale in the low grayscale range. Therefore, the non-uniformity of color coordinates in the low grayscale range and / or mura caused by dithering noise in the low grayscale image can be minimized or eliminated, and the image quality of the display device can be improved.

[0117] However, this disclosure is not limited to the embodiments described above, and various extensions can be made to the display device and the driving method of the display device without departing from the spirit and scope of this disclosure.

[0118] As described above, some embodiments of this disclosure have been described with reference to the accompanying drawings. However, those skilled in the art will understand that various modifications and changes can be made to this disclosure without departing from the spirit and scope of this disclosure as set forth in the appended claims.

Claims

1. A display device, comprising: The display area includes multiple pixels; A low-grayscale jitter controller selects a jitter grayscale based on the input grayscale in the low grayscale range below a threshold grayscale in the input image data, and generates jittered input image data by performing a jitter operation on the input image data in the low grayscale range based on the jitter grayscale. as well as The display driver drives the plurality of pixels based on the jittered input image data. The low-grayscale jitter controller selects a first jitter grayscale in response to a first input grayscale, and selects a second jitter grayscale in response to a second input grayscale smaller than the first input grayscale. Wherein, the second jitter grayscale is greater than the first jitter grayscale.

2. The display device according to claim 1, wherein, The low-grayscale jitter controller includes a memory storing a lookup table, the lookup table including multiple reference grayscales corresponding to each input grayscale within the low grayscale range, and The low grayscale jitter controller responds to the input grayscale and selects one of the plurality of reference grayscales as the jitter grayscale.

3. The display device according to claim 2, wherein, The plurality of reference gray levels are greater than the threshold gray level, and The low-grayscale jitter controller performs the jitter operation by expressing the input grayscale based on the jitter grayscale and the black grayscale.

4. The display device according to claim 3, wherein, For the same dithered grayscale, the ratio of the dithered grayscale applied in the low grayscale dithered region of the display area where the dithering operation is performed increases as the input grayscale increases.

5. The display device according to claim 4, wherein, The low-grayscale jitter controller selects the first jitter grayscale in response to a third input grayscale that is less than the second input grayscale.

6. The display device according to claim 5, wherein, In the low grayscale jitter region of the display area, the second ratio of the second jitter grayscale applied is different from at least one of the first ratio of the first jitter grayscale applied in response to the first input grayscale and the third ratio of the first jitter grayscale applied in response to the third input grayscale.

7. The display device according to claim 6, wherein, In the low grayscale jitter region, the second ratio of the second jitter grayscale applied is less than or equal to the third ratio of the first jitter grayscale applied in response to the third input grayscale.

8. The display device according to claim 5, wherein, The display driver includes a data driver that supplies the jitter grayscale data voltage and the black grayscale black data voltage to the plurality of pixels, and Wherein, the second voltage deviation between the second data voltage of the second jittered grayscale and the black data voltage is greater than the first voltage deviation between the first data voltage of the first jittered grayscale and the black data voltage.

9. The display device according to any one of claims 3 to 8, wherein, The low grayscale range includes grayscale values ​​greater than the black grayscale and equal to or lower than the threshold grayscale. Wherein, the black grayscale is grayscale 0, the threshold grayscale is grayscale 10 of the eight-bit grayscale, and the plurality of reference grayscales are grayscale 11 to grayscale 15 of the eight-bit grayscale.

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