Display apparatus and control method thereof

Abstract

A control method of a display apparatus according to an embodiment of the present invention comprises the steps of: receiving image data from an external device (the image data includes a pixel value corresponding to each of at least one pixel); determining an area requiring display panel compensation by using the pixel values included in the received image data; changing pixel values for the area requiring display panel compensation by using a parameter stored in a memory; and outputting the changed pixel values to a display panel.

Description

Display device and control method thereof

[0001] The present invention relates to display devices. For example, it is directly or indirectly related to compensation technology for OLED panels used in automobiles or mobile phones, but the scope of the present invention is not necessarily limited thereto.

[0002] Flat panel display devices such as liquid crystal display devices, plasma display devices, and electroluminescent display devices are being developed.

[0003] In particular, an electroluminescent display device can be driven with a fast response speed and low power consumption by using a light-emitting diode (LED) or an organic light-emitting diode (OLED) that generates light through the recombination of electrons and holes.

[0004] However, there was a problem where the yield of the display panel was low due to the deterioration of the display device's expressiveness under low-gradation conditions.

[0005] One embodiment of the present invention aims to solve the problem of reduced expressiveness of a display device occurring under low grayscale conditions.

[0006] Through this, we aim to achieve additional objectives of improving the yield of display panels and enhancing quantitative and qualitative image quality.

[0007] A control method for a display device to solve the aforementioned technical problem comprises the steps of: receiving image data from an external device (the image data includes a pixel value corresponding to at least one pixel); determining an area requiring display panel compensation using the pixel value included in the received image data; changing the pixel value for the area requiring display panel compensation using a parameter stored in memory; and outputting the changed pixel value to the display panel.

[0008] The above-mentioned determining step further includes a step of calculating the average value of pixel values ​​included in a block composed of M pixels in the horizontal direction and N pixels in the vertical direction, and a step of considering the block as an area requiring display panel compensation if the calculated average value is less than or equal to a preset reference value.

[0009] The above-mentioned changing step further includes the step of calculating the total sum of pixel values ​​included in the block.

[0010] It is characterized by the fact that the pixel values ​​included in the block are changed differently according to the relationship between the above-calculated total sum and the parameters stored in the memory.

[0011] The above-mentioned determining step may further include a step of determining whether the block determined to be an area requiring display panel compensation is an edge area or a flat area.

[0012] Furthermore, a control method for a display device according to another embodiment of the present invention further includes the step of stopping the changing step when the block determined to be an area requiring display panel compensation is an edge area.

[0013] And, a display device according to one embodiment of the present invention includes a receiving module for receiving image data from an external device (the image data includes at least one pixel value corresponding to each pixel), and a controller for determining an area requiring display panel compensation using the pixel value included in the received image data, changing the pixel value for the area requiring display panel compensation using a parameter stored in memory, and outputting the changed pixel value to the display panel.

[0014] According to one embodiment of the present invention, there is a technical effect of solving the problem of reduced expressiveness of a display device occurring under low grayscale conditions.

[0015] Furthermore, through this, additional objectives such as improving the yield of display panels and enhancing quantitative and qualitative image quality can also be achieved.

[0016] Figure 1 is a diagram showing the signal flow of a Dimura compensation process according to the prior art.

[0017] Figure 2 is a diagram for comparing the results before and after Dimura compensation.

[0018] FIG. 3 is a diagram schematically illustrating a display device according to an embodiment of the present invention.

[0019] FIG. 4 is a block diagram illustrating the controller (300) shown in FIG. 3 in more detail.

[0020] FIG. 5 is a drawing for explaining the function of the operation unit (400) shown in FIG. 4 in more detail.

[0021] FIG. 6 illustrates the pixel values ​​of image data input to a display device according to an embodiment of the present invention.

[0022] FIG. 7 illustrates the pixel value of image data that is changed by a display device according to an embodiment of the present invention.

[0023] And, FIG. 8 is a flowchart illustrating a control method of a display device according to an embodiment of the present invention.

[0024] Throughout the specification, identical reference numbers denote substantially identical components. In the following description, detailed descriptions of components and functions known in the art may be omitted if they are not related to the core components of the invention. The meanings of the terms described in this specification should be understood as follows.

[0025] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0026] The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the present invention are exemplary, and therefore the present invention is not limited to the depicted details. Throughout the specification, the same reference numerals refer to the same components. Furthermore, in describing the present invention, if it is determined that a detailed description of related known technology may unnecessarily obscure the essence of the present invention, such detailed description is omitted.

[0027] Where terms such as 'comprising,' 'having,' 'consisting of,' etc. are used in this specification, other parts may be added unless 'only' is used. Where a component is expressed in the singular, it includes cases where it is included in the plural unless specifically stated otherwise.

[0028] In interpreting the components, they are interpreted to include a margin of error even in the absence of a separate explicit statement.

[0029] In the case of describing a positional relationship, for example, when the positional relationship between two parts is described using expressions such as 'on,' 'upper,' 'lower,' or 'next to,' one or more other parts may be located between the two parts unless 'immediately' or 'directly' is used.

[0030] In the case of an explanation of a temporal relationship, for example, when a temporal sequence is explained using 'after', 'following', 'next', 'before', etc., it may include cases where the sequence is not continuous unless 'immediately' or 'directly' is used.

[0031] Although terms such as "first," "second," etc. are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the technical scope of the present invention.

[0032] The term “at least one” should be understood to include all combinations that can be presented from one or more related items. For example, the meaning of “at least one of the first item, the second item and the third item” may mean not only the first item, the second item or the third item individually, but also all combinations of items that can be presented from two or more of the first item, the second item and the third item.

[0033] The features of each of the various embodiments of the present invention may be combined or combined with one another, either partially or wholly, and may technically enable various interlocking and operation. Each embodiment may be implemented independently of one another or may be implemented together in an associated relationship.

[0034] Hereinafter, embodiments of the present specification will be described in detail with reference to the attached drawings.

[0035] Figure 1 is a diagram showing the signal flow of a Dimura compensation process according to the prior art.

[0036] As illustrated in FIG. 1, the data processing circuit (110) can transmit image data (RGB) having certain grayscale values ​​to the source driver (120). The source driver (120) can convert these grayscale values ​​into a data voltage (Vd) and supply it to the display panel (140). At this time, gamma may be applied to the data voltage (Vd).

[0037] Also, the luminance (Lx) of each pixel of the display panel (140) can be controlled according to the data voltage (Vd). The luminance (Lx) of each pixel may differ from one another. The variation in luminance (Lx) of the pixels is also referred to as mura.

[0038] The camera device (220) can photograph the display panel (140), measure the brightness value for each pixel, and store it.

[0039] And, the mura compensation device (210) receives a digitized luminance value (DLx) from the camera device (220) and can generate a compensation value to resolve the mura phenomenon using the luminance value (DLx) of each pixel.

[0040] This process can be performed repeatedly for specific grayscale values. For example, for five major grayscale values ​​(e.g., 32, 64, 128, 192, 200) among the grayscale values ​​of 0-255, a luminance value (DLx) for each pixel may be stored in the Dimura compensation device (210).

[0041] The dimura compensation device (210) can acquire multiple luminance values ​​(DLx) corresponding to these multiple grayscale values ​​and calculate compensation values ​​(DCp) corresponding to the multiple grayscale values ​​so as to resolve the dimura phenomenon caused by the difference between the target luminance values ​​and the luminance values ​​(DLx). Here, the target luminance values ​​can be determined mainly according to the luminance values ​​of a block located in the center of the display panel.

[0042] Figure 2 is a diagram for comparing the results before and after Dimura compensation.

[0043] As mentioned above, during the display panel production process, a camera is used to photograph the display panel, and the resulting image is used to correct the deviation (mura) and store the correction data. Then, when the display panel is in operation, compensating for the deviation of each pixel using the stored correction data is called mura compensation.

[0044] Figure 2(a) is a captured image of a display panel output before Dimura compensation for pseudo-color, whereas Figure 2(b) is a captured image of the same image output by a display panel after Dimura compensation for pseudo-color.

[0045] Compared to (a) of Fig. 2, (b) of Fig. 2 has the advantage of outputting a uniform image without brightness variation.

[0046] However, according to conventional dimura compensation technology, deviation compensation is possible for pixel values ​​above a certain brightness level using images captured by a camera, but there was a problem in that deviation correction was difficult for low-brightness images because capturing them with a camera was difficult.

[0047] One embodiment of the present invention aims to solve the problem of reduced expressiveness of display devices, such as OLEDs, by intentionally changing pixel values ​​in such situations to have values ​​that are robust to deviations.

[0048] FIG. 3 is a diagram schematically illustrating a display device according to an embodiment of the present invention.

[0049] A display device according to one embodiment of the present invention includes, as shown in FIG. 3, a receiving module (310), a controller (300), and a display panel (320), etc. The receiving module (310) shown in FIG. 3 corresponds to, for example, a System on Chip (SoC), etc., and the controller (300) shown in FIG. 3 corresponds to, for example, a Display Driver Integrated Circuit (DDIC), etc.

[0050] First, the receiving module (310) can receive image data from an external device. In particular, the image data includes, for example, at least one pixel value corresponding to each pixel.

[0051] The controller (300) determines the area requiring display panel compensation by using the pixel values ​​included in the received image data.

[0052] Furthermore, the controller (300) changes the pixel value for the area requiring compensation of the display panel using parameters stored in memory.

[0053] And, the controller (300) outputs the changed pixel value to the display panel (320).

[0054] Additionally, the controller (300) calculates the average value of pixel values ​​included in a block consisting of M pixels in the horizontal direction and N pixels in the vertical direction, and if the calculated average value is less than or equal to a preset reference value, the block is considered an area requiring display panel compensation.

[0055] Furthermore, the controller (300) may calculate the total sum of the pixel values ​​included in the block. The pixel values ​​included in the block are changed differently depending on the relationship between the calculated total sum and the parameters stored in memory. More specific embodiments related to this will be described in more detail below with reference to FIGS. 6 and 7.

[0056] Meanwhile, the controller (300) may additionally determine whether the block determined to be an area requiring display panel compensation is an edge area or a flat area.

[0057] If the block determined to be an area requiring display panel compensation is an edge area, the controller (300) is designed not to change the input pixel value.

[0058] The detailed functions of the controller (300) shown in FIG. 3 will be explained in more detail below with reference to FIG. 4.

[0059] FIG. 4 is a block diagram illustrating the controller (300) shown in FIG. 3 in more detail.

[0060] The controller (400) illustrated in FIG. 4 includes a preprocessing unit (410), a detection unit (420), a memory (430), a calculation unit (440), and a synthesis unit (450), etc. In particular, the memory (430) may consist of a first memory (431) and a second memory (432).

[0061] First, the preprocessing unit (410) can be designed to preprocess pixel values ​​using the result of modeling the unique characteristics of the display panel.

[0062] In the low-gradation range of an image, the characteristics of the display panel vary from panel to panel and show different trends depending on each color channel.

[0063] Therefore, by modeling the characteristics of the display panel and then performing preprocessing on the image data to reflect them, the accuracy of the computation unit (440) can be improved.

[0064] Basically, image data is processed in the luminance domain by performing degamma processing using 2.2 gamma. At this time, the luminance that can be observed / measured on the display panel may differ significantly from the ideal value in the low-grayage area. Therefore, by reflecting the unique numerical value displayed by the display panel in a form similar to degamma, it is advantageous for maintaining luminance and color representation when processing image data.

[0065] As described above, the present invention considers the low-gradation area of ​​the image data as the Region of Interest (ROI). The high-gradation area does not provide a high technical effect due to the present invention and, on the contrary, poses a risk of degrading the image quality of the input image.

[0066] Accordingly, the detection unit (420) is designed to pre-detect the area to be compensated for by the display panel so that the compensation operation is performed in a limited manner.

[0067] For example, the detection area can be determined by selecting a block of size M x N and determining the size of the average pixel value of the pixels within the block.

[0068] If compensation is performed simply using only the size of a single pixel, the characteristics of the original data may be corrupted due to the influence of surrounding pixels, or it may be difficult to expect the improvement effect of the present invention; therefore, the design ensures that low-gradation areas are determined in fixed block units.

[0069] Meanwhile, the detection unit (420) determines the low-gradation area by, for example, determining that the area is low-gradation when the sum of all pixel values ​​included in an MxN (ex: 2x2, etc.) block is less than or equal to a certain threshold value, and performing a pixel value rearrangement process.

[0070] Depending on the range in which a problem of reduced expressiveness occurs at low gray levels for any display panel, the aforementioned reference value may be, for example, 4 gray or less or 9 gray or less. However, the present invention is not necessarily limited thereto, and the examples of the aforementioned reference values ​​may be changed depending on the specifications or characteristics of the display panel.

[0071] The first memory (431) stores parameters related to display panel compensation.

[0072] The compensation intensity for low-grayage areas requiring compensation varies depending on the type and characteristics of the display panel, color channels, etc. Therefore, compensation values ​​and thresholds corresponding to each pixel value are stored and used during calculations.

[0073] If it is difficult to store parameters for every pixel of the image data, parameter values ​​can be assigned by specifying arbitrary intervals. In this case, unstored parameter values ​​can be predicted and used using various interpolation methods.

[0074] The second memory (432) stores parameters related to the operating environment.

[0075] The characteristics of the low-gradation area vary depending on the operating environment of the display panel, such as DBV (Display Brightness Value) or frame rate, or various external environmental factors such as the temperature of the display panel and ambient temperature. Therefore, parameters such as gain values ​​or offset values ​​are stored and used to compensate for this.

[0076] Similar to the first memory (431) described above, each parameter stored in the second memory (432) can be used by storing it in a sampled form, and can be used by methods such as using interpolation or specifying a representative value for each area.

[0077] The calculation unit (440) calculates compensation data based on various parameters stored in the first memory (431) or the second memory (432).

[0078] That is, the operation unit (440) utilizes various parameters stored in advance to calculate and extract compensation data that reflects the local characteristics of the image.

[0079] At this time, a block size of M x N is specified so that the compensation process proceeds independently for each block. In particular, during the processing, a pixel compensation value capable of maintaining the same luminance as the input image data is calculated and rearranged within the block. An embodiment related to this will be described in more detail below with reference to FIG. 5.

[0080] The synthesis unit (450) outputs an image that combines the compensation data calculated by the operation unit (440). The result of the compensation data operation is reprocessed and synthesized according to a specific order through processes such as dithering. At this time, the synthesis process may cause problems that could actually degrade the image quality in specific areas of the image. Therefore, it is necessary to resolve concerns about image quality degradation by minimizing the synthesis process for specific areas.

[0081] The term "dithering" as described in this specification refers to, for example, recirculating pixel values ​​within an MxN block to minimize the difference from the original image that occurs during the pixel value calculation process. This provides a technical effect of reducing artifacts.

[0082] For example, if image data around edges is dithered, movement can be observed as pixels are rearranged around the edges every frame. It is necessary to dither only the low-gradation areas of flat regions.

[0083] Meanwhile, when the pixel values ​​of pixels within an MxN block are compared and the difference is greater than a preset threshold, it is determined to be an edge region.

[0084] FIG. 5 is a drawing for explaining the function of the operation unit (400) shown in FIG. 4 in more detail.

[0085] First, the block (2x2) shown in FIG. 5 (a) represents the input pixel values ​​of the image data. In particular, it is assumed that the block is a low-gradation area.

[0086] At this time, the operation unit illustrated in FIG. 5(b) changes the output pixel value differently as illustrated in FIG. 5(c) by using parameters stored in memory, etc. However, the total sum of the input pixel values ​​illustrated in FIG. 5(a) and the total sum of the output pixel values ​​illustrated in FIG. 5(c) are designed to be the same.

[0087] Since the sum of the input pixel values ​​and the sum of the output pixel values ​​must be kept the same to maintain the average brightness level that the pixels within the block (e.g., MxN) area are intended to represent, there is an advantage that even if some pixel values ​​change within the block, the user can perceive the block (MxN) area at an equivalent level.

[0088] However, a more specific embodiment in which the operation unit changes the pixel value differently will be explained below with reference to FIGS. 6 and FIGS. 7.

[0089] FIG. 6 illustrates the pixel value of image data input to a display device according to an embodiment of the present invention. FIG. 7 illustrates the pixel value of image data that is changed by a display device according to an embodiment of the present invention.

[0090] First, as shown in FIG. 6, let us assume that the pixel value of P0 is input to the first pixel (610), the pixel value of P1 is input to the second pixel (620), the pixel value of P2 is input to the third pixel (630), and the pixel value of P3 is input to the fourth pixel (640).

[0091] At this time, the controller in the device according to one embodiment of the present invention calculates the sum of all pixel values ​​in the block (2x2).

[0092] Then, depending on the result of dividing the sum of all pixel values ​​in the block (2x2) by a specific parameter stored in memory (e.g., a pixel value to be relocated), one of the four embodiments shown in FIG. 7 is selectively output.

[0093] When the sum of all pixel values ​​in a block (2x2) is divided by a specific parameter (Div) stored in memory and the quotient (Quo) is 0, three pixel values ​​are set to 0 as shown in FIG. 7 (a), and the remaining one pixel value is set as the remainder (rem) of the division operation.

[0094] When the sum of all pixel values ​​in a block (2x2) is divided by a specific parameter (Div) stored in memory and the quotient (Quo) is 1, as shown in FIG. 7 (b), two pixel values ​​are set to 0, the remaining pixel value is set to the remainder (rem) of the division operation, and the last pixel value is set to the specific parameter (Div) stored in memory.

[0095] Meanwhile, for example, as the Display Brightness Value (DBV) decreases, it is desirable for the value of a specific parameter (Div) stored in the memory to increase, but the present invention is not necessarily limited thereto.

[0096] Alternatively, depending on the frame rate or ambient temperature, the specific parameter (Div) value may be designed to increase as the pixel value becomes darker.

[0097] When the sum of all pixel values ​​in a block (2x2) is divided by a specific parameter (Div) stored in memory and the quotient (Quo) is 2, as shown in Fig. 7 (c), one pixel value is set to 0, two pixel values ​​are set to the specific parameter (Div) stored in memory, and the last pixel value is set to the remainder (rem) of the division operation.

[0098] When the sum of all pixel values ​​in a block (2x2) is divided by a specific parameter (Div) stored in memory and the quotient (Quo) is 3, as shown in FIG. 7 (d), three pixel values ​​are set to the specific parameter (Div) stored in memory and the last pixel value is set to the remainder (rem) of the division operation.

[0099] In FIG. 7, the block is exemplified as 2 x 2, but the present invention is not necessarily limited thereto.

[0100] Also, FIG. 8 is a flowchart illustrating a control method for a display device according to an embodiment of the present invention. Those skilled in the art can interpret FIG. 8 by referring to the preceding drawings.

[0101] A display device according to an embodiment of the present invention receives image data from an external device (S810). At this time, the image data includes a pixel value corresponding to at least one pixel.

[0102] Furthermore, the display device determines an area requiring display panel compensation by using pixel values ​​included in the received image data (S820).

[0103] Additionally, the display device changes the pixel value for the area requiring the display panel compensation using parameters stored in memory (S830).

[0104] And, the display device outputs the changed pixel value to the display panel (S840).

[0105] Meanwhile, step S820 calculates the average value of pixel values ​​included in a block composed of M pixels in the horizontal direction and N pixels in the vertical direction, and if the calculated average value is less than or equal to a preset reference value, the block is considered an area requiring display panel compensation.

[0106] Furthermore, step S830 may further include a step of calculating the total sum of pixel values ​​included in the block.

[0107] The pixel values ​​included in the block are changed differently depending on the relationship between the calculated total sum and the parameters stored in the memory. An example related to this is omitted as it was described in detail in the previous FIG. 7.

[0108] And, step S820 may further include a step of determining whether the block determined to be an area requiring display panel compensation is an edge area or a flat area.

[0109] If the block determined to be an area requiring display panel compensation is an edge area, the display device is designed to stop step S830.

[0110] Those skilled in the art to which the present invention pertains will understand that the above-described invention may be implemented in other specific forms without altering its technical concept or essential features.

[0111] Additionally, the methods described herein may be implemented at least partially using one or more computer programs or components. These components may be provided as a series of computer instructions via a computer-readable or machine-readable medium including volatile and non-volatile memory. The instructions may be provided as software or firmware and may be implemented wholly or partially in hardware configurations such as ASICs, FPGAs, DSPs, or other similar devices. The instructions may be configured to be executed by one or more processors or other hardware configurations, which perform or are capable of performing all or part of the methods and procedures disclosed herein when executing the series of computer instructions.

[0112] Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. The scope of the invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the invention.

[0113] Various embodiments for implementing the present invention have been described in detail in the previous table of contents.

[0114] Since the present invention is applicable to display devices, its industrial applicability is recognized.

Claims

1. In a method for controlling a display device, A step of receiving image data from an external device—the image data includes at least one pixel value corresponding to each pixel—; A step of determining an area requiring display panel compensation using pixel values ​​included in the received image data; A step of changing pixel values ​​for the area requiring compensation of the display panel using parameters stored in memory; and Step of outputting the above-mentioned changed pixel value to the display panel A control method for a display device characterized by including 2. In Paragraph 1, The above-mentioned decision-making step is, A step of calculating the average value of pixel values ​​included in a block composed of M pixels in the horizontal direction and N pixels in the vertical direction; and If the above calculated average value is less than or equal to a preset reference value, the step of considering the block as an area requiring display panel compensation A control method for a display device characterized by further including 3. In Paragraph 2, The above-mentioned changing step is, Step of calculating the total sum of pixel values ​​included in the above block A control method for a display device characterized by further including 4. In Paragraph 3, A control method for a display device characterized by changing pixel values ​​included in the block differently according to the relationship between the calculated total sum and the parameters stored in the memory.

5. In Paragraph 1, The above-mentioned decision-making step is, A step of determining whether a block determined to be an area requiring display panel compensation is an edge area or a flat area. A control method for a display device characterized by further including 6. In Paragraph 5, If the block determined to be an area requiring display panel compensation is an edge area, the step of stopping the above-mentioned changing step. A control method for a display device characterized by further including 7. In a display device, A receiving module for receiving image data from an external device—the image data includes at least one pixel value corresponding to each pixel—; and Using the pixel values ​​included in the received image data above, the area requiring display panel compensation is determined, and Using parameters stored in memory, pixel values ​​are changed for the area requiring compensation of the display panel, and A controller that outputs the above-mentioned changed pixel value to the above-mentioned display panel A display device characterized by including 8. In Paragraph 7, The above controller is, Calculate the average value of pixel values ​​included in a block consisting of M pixels in the horizontal direction and N pixels in the vertical direction, and A display device characterized by considering the block as an area requiring display panel compensation when the above-determined average value is less than or equal to a preset reference value.

9. In Paragraph 8, The above controller is, A display device characterized by calculating the total sum of pixel values ​​included in the above block.

10. In Paragraph 9, A display device characterized in that the pixel values ​​included in the block are changed differently according to the relationship between the above-calculated total sum and the parameters stored in the memory.

11. In Paragraph 7, The above controller is, A display device characterized by determining whether a block determined to be an area requiring display panel compensation is an edge area or a flat area.

12. In Paragraph 11, The above controller is, A display device characterized by stopping the changing step when the block determined to be an area requiring display panel compensation is an edge area.

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