Display device and method for measuring brightness distribution thereof

Abstract

The present application relates to a display device and a method for measuring the brightness distribution thereof. A method for measuring the brightness distribution of a display device including pixels divided into blocks, comprising: measuring a first reference brightness distribution when a partial area of ​​each of the blocks is in a display state and the remaining area of ​​each of the blocks is in a non-display state; measuring a first brightness distribution when the entire area of ​​a first block among a plurality of blocks is in a display state, a partial area of ​​each of the remaining blocks is in a display state, and the remaining area of ​​each of the remaining blocks is in a non-display state; and measuring a second brightness distribution when the entire area of ​​a second block among a plurality of blocks is in a display state, a partial area of ​​each of the remaining blocks is in a display state, and the remaining area of ​​each of the remaining blocks is in a non-display state.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and all benefits derived from Korean Patent Application No. 10-2020-0059987, filed on May 19, 2020, the disclosure of which is hereby incorporated by reference in its entirety. Technical Field

[0003] Embodiments according to the present invention relate to a display device and a method for measuring brightness distribution thereof. Background Art

[0004] As information technology develops, the importance of display devices as a connection medium between users and information has been emphasized. In response to this, the use of display devices such as liquid crystal display devices, organic light emitting display devices, plasma display devices, and the like has been increasing.

[0005] A display device may include multiple pixels, and the pixels may use at least one common power supply voltage. The voltage drop (IR drop) in the power supply voltage across the pixels may vary depending on the pixel's location and grayscale value. To address mura display and similar issues, a data voltage must be supplied to the pixels with appropriately compensated voltage drop.

[0006] There is a method that pre-calculates the internal resistance of the display device and uses this internal resistance to calculate the voltage drop. However, because the calculated voltage drop differs from the actual brightness drop during display, it may be difficult to effectively solve the mura display problem. Summary of the Invention

[0007] The technical problem to be solved is to provide a display device and a method for measuring its brightness distribution that can effectively solve the mura display problem by reflecting the brightness reduction during actual display.

[0008] As a method for measuring the brightness distribution of a display device including multiple pixels divided into multiple blocks, the method for measuring the brightness distribution according to an embodiment of the present invention includes: measuring a first reference brightness distribution when a partial area of ​​each of the multiple blocks is in a display state and the remaining area of ​​each of the multiple blocks is in a non-display state; measuring a first brightness distribution when the entire area of ​​a first block among the multiple blocks is in a display state, a partial area of ​​each of the first multiple remaining blocks is in a display state, and the remaining area of ​​each of the first multiple remaining blocks is in a non-display state, wherein the first multiple remaining blocks are multiple blocks other than the first block; and measuring a second brightness distribution when the entire area of ​​a second block among the multiple blocks is in a display state, a partial area of ​​each of the second multiple remaining blocks is in a display state, and the remaining area of ​​each of the second multiple remaining blocks is in a non-display state, wherein the second multiple remaining blocks are multiple blocks other than the second block.

[0009] The remaining area may be larger than the partial area.

[0010] In measuring the first reference luminance distribution, a partial area of ​​each of the plurality of blocks may display white. In measuring the first luminance distribution, the entire area of ​​the first block may display white, and a partial area of ​​each of the first plurality of remaining blocks may display white. In measuring the second luminance distribution, the entire area of ​​the second block may display white, and a partial area of ​​each of the second plurality of remaining blocks may display white.

[0011] In measuring the first reference luminance distribution, a partial area of ​​each of the plurality of blocks may display the first color. In measuring the first luminance distribution, a partial area of ​​the first block may display the first color, the remaining area of ​​the first block may display white, and a partial area of ​​each of the first plurality of remaining blocks may display the first color. In measuring the second luminance distribution, a partial area of ​​the second block may display the first color, the remaining area of ​​the second block may display white, and a partial area of ​​each of the second plurality of remaining blocks may display the first color.

[0012] The method for measuring brightness distribution may also include: measuring a second reference brightness distribution when a partial area of ​​each of a plurality of blocks displays a second color and a remaining area of ​​each of the plurality of blocks is in a non-display state; measuring a third brightness distribution when a partial area of ​​the first block displays the second color, the remaining area of ​​the first block displays white, a partial area of ​​each of the first plurality of remaining blocks displays the second color, and the remaining area of ​​each of the first plurality of remaining blocks is in a non-display state; and measuring a fourth brightness distribution when a partial area of ​​the second block displays the second color, the remaining area of ​​the second block displays white, a partial area of ​​each of the second plurality of remaining blocks displays the second color, and the remaining area of ​​each of the second plurality of remaining blocks is in a non-display state.

[0013] In measuring the first reference luminance distribution, measuring the first luminance distribution, and measuring the second luminance distribution, the partial area may display the first color by emitting pixels of the first color among the plurality of pixels included in the partial area and not emitting pixels of the remaining colors except the first color. In measuring the second reference luminance distribution, measuring the third luminance distribution, and measuring the fourth luminance distribution, the partial area may display the second color by emitting pixels of the second color among the plurality of pixels included in the partial area and not emitting pixels of the remaining colors except the second color.

[0014] The method for measuring luminance distribution may further include storing a difference between the first reference luminance distribution and the first luminance distribution as a first block luminance distribution; and storing a difference between the first reference luminance distribution and the second luminance distribution as a second block luminance distribution.

[0015] A display device according to an embodiment of the present invention includes: a plurality of pixels divided into a plurality of blocks; and a grayscale converter that converts a plurality of input grayscales for the plurality of pixels into a plurality of output grayscales. Each of the plurality of blocks may include at least two pixels, and the grayscale converter may generate the plurality of output grayscales based on a plurality of block currents calculated from the plurality of input grayscales and a plurality of pre-stored block luminance distributions.

[0016] The grayscale converter may include a luminance drop amount calculator that scales each of the plurality of block luminance distributions corresponding to a magnitude of each of the plurality of block currents.

[0017] The brightness drop amount calculator may scale the plurality of block brightness distributions, and the brightness drop amount calculator scales the block brightness distribution to be smaller as the block current corresponding to the block brightness distribution is smaller.

[0018] The brightness drop amount calculator may generate a total brightness distribution by summing the scaled brightness distributions of the plurality of blocks.

[0019] The brightness drop amount calculator may interpolate the total brightness distribution to calculate a plurality of brightness drop amounts of a plurality of pixels.

[0020] The grayscale converter may further include a luminance domain converter that converts the plurality of input grayscales into a plurality of input luminances in a luminance domain.

[0021] The luminance domain converter may apply a gamma curve to a plurality of input grayscales to convert the plurality of input grayscales into a plurality of input luminances.

[0022] The grayscale converter may further include a compensation value calculator that calculates a plurality of compensation values ​​based on the plurality of input luminances and the plurality of luminance drop amounts.

[0023] The compensation value calculator may calculate a plurality of compensation values ​​according to a ratio of each of the plurality of luminance drop amounts to each of the plurality of input luminances.

[0024] As the ratio of the brightness drop amount to the input brightness increases, the compensation value calculator may calculate a larger compensation value.

[0025] The grayscale converter may further include an output grayscale calculator that sums the plurality of input grayscales and the plurality of compensation values ​​to calculate a plurality of output grayscales.

[0026] Each of the plurality of block currents may be a sum value of a plurality of driving currents desired to flow in light emitting diodes of a plurality of pixels included in each of the plurality of blocks.

[0027] The light emitting diodes may be commonly connected between the first power line and the second power line. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0029] Figure 1 is a block diagram for explaining a display device according to an embodiment of the present invention.

[0030] Figure 2 is a circuit diagram for explaining a pixel according to an embodiment of the present invention.

[0031] Figure 3 is a diagram for explaining blocks according to an embodiment of the present invention.

[0032] Figure 4 is a block diagram for explaining a grayscale converter according to an embodiment of the present invention.

[0033] Figure 5 and Figure 6 is a diagram for explaining a method for measuring luminance distribution according to an embodiment of the present invention.

[0034] Figure 7 and Figure 8 is a diagram for explaining block current according to an embodiment of the present invention.

[0035] Figure 9 1 is a diagram for explaining the amount of brightness reduction according to an embodiment of the present invention.

[0036] Figure 10 is a diagram for explaining a luminance domain converter according to an embodiment of the present invention.

[0037] Figure 11 is a diagram for explaining a method for measuring brightness distribution according to another embodiment of the present invention. DETAILED DESCRIPTION

[0038] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. The present invention can be implemented in various forms and is not limited to the embodiments described herein.

[0039] In order to clearly describe the present invention, parts that are not related to the description are omitted, and throughout the specification, the same or similar components are symbolized by the same reference numerals. Therefore, the above-mentioned reference numerals can be used in other figures. It will be understood that although the terms "first", "second", "third", etc. can be used to describe various elements, components, areas, layers and / or parts in this article, these elements, components, areas, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer or part from another element, component, area, layer or part. Therefore, without departing from the teachings herein, the first element, component, area, layer or part discussed below can be referred to as the second element, component, area, layer or part. The professional terms used herein are only for the purpose of describing a specific embodiment and are not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include plural forms, including "at least one", unless the context clearly indicates otherwise. "At least one" should not be interpreted as being limited to "a" or "an". "Or" means "and / or". As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It will be further understood that when used in this specification, the terms "comprise" and / or "comprising" or "include" and / or "including" specify the presence of stated features, regions, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components and / or groups thereof.

[0040] In addition, for the convenience of description, the size and thickness of each component shown in the drawings are arbitrarily shown, and therefore, the present invention is not necessarily limited to those shown in the drawings. In the drawings, the thickness may be exaggerated to clearly show layers and regions.

[0041] Figure 1 is a block diagram for explaining a display device 10 according to an embodiment of the present invention.

[0042] Reference Figure 1 , a display device 10 according to an embodiment of the present invention may include a timing controller 11 , a data driver 12 , a scan driver 13 , a pixel unit 14 (in other words, a display panel), and a grayscale converter 15 .

[0043] The timing controller 11 may receive input grayscale and control signals for each frame (ie, input image) from an external processor and may provide control signals suitable for each specification to the data driver 12, the scan driver 13, and the like to display the frame.

[0044] The grayscale converter 15 can provide an output grayscale GVo obtained by converting the input grayscale GVi (see Figure 4 The timing controller 11 may provide the output grayscale GVo to the data driver 12. The grayscale converter 15 may be composed of an integrated circuit (IC) chip integrated with the timing controller 11 or the data driver 12, or may be composed of an IC separate from the timing controller 11 and the data driver 12. In another embodiment, the grayscale converter 15 may be implemented by software in the timing controller 11 or the data driver 12.

[0045] The data driver 12 may generate data voltages using the output grayscale GVo and a control signal, and supply the data voltages to the plurality of data lines DL1, DL2, DL3, ..., and DLn. For example, the data driver 12 may sample the output grayscale GVo using a clock signal, and apply data voltages corresponding to the output grayscale GVo to the plurality of data lines DL1 to DLn in units of pixel rows, where n may be an integer greater than 0. A pixel row may represent a group of pixels connected to one scan line.

[0046] The scan driver 13 may receive a clock signal, a scan start signal, and the like from the timing controller 11 , generate a scan signal, and provide the scan signal to a plurality of scan lines SL1 , SL2 , SL3 , . . . , and SLm, where m may be an integer greater than 0.

[0047] The scan driver 13 may sequentially supply a scan signal having an on-level pulse to the plurality of scan lines SL1 to SLm. The scan driver 13 may be configured in the form of a shift register and may include a plurality of scan stages. The scan driver 13 may generate a scan signal by sequentially transmitting a scan start signal in the form of an on-level pulse to the next scan stage under the control of a clock signal.

[0048] The pixel unit 14 may include a plurality of pixels. Each pixel PXij may be connected to a corresponding data line and a scan line, where i and j may be integers greater than 0. The pixel PXij may refer to a pixel in which a scan transistor is connected to the i-th scan line SLi and the j-th data line DLj. The plurality of pixels may be commonly connected to a first power line ELVDDL and a second power line ELVSSL (refer to Figure 2 ).

[0049] Figure 2 is a circuit diagram for explaining a pixel PXij according to an embodiment of the present invention.

[0050] Reference Figure 2 , the pixel PXij may be a pixel emitting light of the first color. The pixel emitting light of the second color or the third color may have substantially the same configuration as the pixel PXij except for the light emitting diode LD, and thus repeated description of the same configuration will be omitted.

[0051] For example, the first color may be one of red, green, and blue, the second color may be one of red, green, and blue other than the first color, and the third color may be the remaining color of red, green, and blue other than the first and second colors. In addition, in another embodiment, magenta, cyan, and yellow may be used as the first to third colors instead of red, green, and blue.

[0052] The pixel PXij may include a plurality of transistors T1 and T2 , a storage capacitor Cst1 , and a light emitting diode LD.

[0053] In this embodiment, the plurality of transistors T1 and T2 are shown as P-type transistors, for example, PMOS transistors. However, those skilled in the art will be able to construct a pixel circuit with the same functionality using N-type transistors, for example, NMOS transistors.

[0054] The transistor T2 may include a gate electrode connected to the scan line SLi, a first electrode connected to the data line DLj, and a second electrode connected to the gate electrode of the transistor T1. The transistor T2 may be referred to as a scan transistor.

[0055] The transistor T1 may include a gate electrode connected to the second electrode of the transistor T2, a first electrode connected to the first power line ELVDDL, and a second electrode connected to the anode of the light emitting diode LD. The transistor T1 may be referred to as a driving transistor.

[0056] The storage capacitor Cst1 may connect the first electrode and the gate electrode of the transistor T1.

[0057] The light emitting diode LD may include an anode connected to the second electrode of the transistor T1 and a cathode connected to the second power supply line ELVSSL. The light emitting diode LD may be an element that emits light having a wavelength corresponding to the first color. The light emitting diode LD may be an organic light emitting diode, or may be an inorganic light emitting diode such as a micro-LED (Light Emitting Diod) and a quantum dot light emitting diode. In addition, the light emitting diode LD may be a light emitting element composed of or including organic and inorganic materials. In this embodiment, only one light emitting diode LD is shown, but in another embodiment, a plurality of sub-light emitting diodes may be connected in series, in parallel, or in series and in parallel to replace the light emitting diode LD.

[0058] When a scan signal of a turn-on level (low level) is supplied to the gate electrode of the transistor T2 through the scan line SLi, the transistor T2 can connect the data line DLj to the first electrode of the storage capacitor Cst1. Therefore, a voltage according to the difference between the data voltage applied through the data line DLj and the first power supply voltage ELVDD can be written to the storage capacitor Cst1.

[0059] The transistor T1 may allow a driving current determined by the voltage written to the storage capacitor Cst1 to flow from the first power line ELVDDL to the second power line ELVSSL. The light emitting diode LD may emit light having a brightness according to the amount of the driving current. The light emitting diodes LD of the plurality of pixels may be commonly connected between the first power line ELVDDL and the second power line ELVSSL.

[0060] Figure 3 BLK11 to BLK34 are diagrams for explaining a plurality of blocks BLK11 to BLK34 according to an embodiment of the present invention.

[0061] Reference Figure 3 , a plurality of pixels of the pixel unit 14 may be divided into a plurality of blocks BLK11, BLK12, BLK13, BLK14, BLK21, BLK22, BLK23, BLK24, BLK31, BLK32, BLK33, and BLK34. Each of the plurality of blocks BLK11 to BLK34 may include at least two pixels.

[0062] In an embodiment, for example, when the pixel unit 14 has an ultra-high definition (UHD) resolution, the pixel unit 14 may include 3840×2160 pixels. In this case, 3840 pixels may be arranged on a horizontal line. For example, 3840 pixels may be connected to a scan line. In this case, 2160 pixels may be arranged on a vertical line. For example, 2160 pixels may be connected to a data line.

[0063] For example, the pixel unit 14 may be divided into 100 blocks. Each block may include the same number of pixels. For example, each block may include 384×216 pixels. However, for convenience of description, the pixel unit 14 divided into 12 blocks BLK11 to BLK34 will be described as an example.

[0064] Figure 4 is a block diagram for explaining the grayscale converter 15 according to the embodiment of the present invention. Figure 5 and Figure 6 is a diagram for explaining a method for measuring luminance distribution according to an embodiment of the present invention. Figure 7 and Figure 8 is a diagram for explaining block current according to an embodiment of the present invention. Figure 9 1 is a diagram for explaining the amount of brightness reduction according to an embodiment of the present invention. Figure 10 15 is a diagram for explaining the luminance domain converter 154 according to an embodiment of the present invention.

[0065] Reference Figure 4 The grayscale converter 15 according to an embodiment of the present invention may include a block luminance distribution storage unit 151, a block current calculator 152, a luminance drop amount calculator 153, a luminance domain converter 154, a compensation value calculator 155, and an output grayscale calculator 156.

[0066] The grayscale converter 15 may generate an output grayscale GVo based on the block current BLC calculated from the input grayscale GVi and the stored block luminance distribution BLD.

[0067] The block luminance distribution storage unit 151 may pre-store a plurality of block luminance distributions BLD. The block luminance distribution storage unit 151 may be configured as a memory separate from other memories or as a part of another memory.

[0068] Reference Figure 5 and Figure 6 , the brightness distribution measurement of the display device 10 can be performed before the display device 10 is put on the market. For example, the display device 10 can display a plurality of patterns, and the camera CAM can capture the patterns displayed on the pixel unit 14 to measure the brightness distribution. The block brightness distribution BLD calculated based on the measured brightness distribution can be stored in the block brightness distribution storage unit 151. Thereafter, the display device 10 can be put on the market. The block brightness distribution BLD based on the brightness distribution can be calculated by an external calculation device.

[0069] For example, when Figure 6As shown in the first figure of FIG, when the plurality of partial regions BLD11r, BLD12r, ..., and BLD34r of the plurality of blocks BLK11 to BLK34 are in a display state and the remaining regions of the plurality of blocks BLK11 to BLK34 are in a non-display state, the camera CAM may measure a first reference luminance distribution BLDr. In the step of measuring the first reference luminance distribution BLDr, the plurality of partial regions BLD11r, BLD12r, ..., and BLD34r of the plurality of blocks BLK11 to BLK34 may display white (i.e., a maximum grayscale).

[0070] In this case, the plurality of partial regions BLD11r, BLD12r, ..., and BLD34r may be the minimum area in which the camera CAM measures the brightness of each of the plurality of blocks BLK11 to BLK34. The plurality of partial regions BLD11r, BLD12r, ..., and BLD34r may be referred to as an observation area. The area of ​​the plurality of partial regions BLD11r, BLD12r, ..., and BLD34r is sufficiently small that the voltage drop caused by the display state of the plurality of partial regions BLD11r, BLD12r, ..., and BLD34r is negligible.

[0071] The remaining area may refer to an area in which the plurality of partial areas BLD11r, BLD12r, ..., and BLD34r are excluded from the entire area of ​​each of the plurality of blocks BLK11 to BLK34. The camera CAM may not measure the brightness of the remaining area. The remaining area may be referred to as a non-observation area. The remaining area may be larger than the plurality of partial areas BLD11r, BLD12r, ..., and BLD34r. That is, the number of pixels included in the remaining area may be larger than the number of pixels included in the plurality of partial areas BLD11r, BLD12r, ..., and BLD34r. The area of ​​the remaining area is large enough so that a voltage drop may occur when the remaining area is in a display state. When the remaining area emits light with high brightness or emits light close to a white grayscale, the amount of voltage drop may increase.

[0072] When measuring the first reference brightness distribution BLDr, since the remaining areas of all the plurality of blocks BLK11 to BLK34 are in a non-display state, the first reference brightness distribution BLDr may include the reference brightness of the plurality of blocks BLK11 to BLK34 where no voltage drop occurs. In this case, the reference brightness is the brightness of the plurality of partial areas BLD11r, BLD12r, . . . , and BLD34r of the plurality of blocks BLK11 to BLK34.

[0073] When the entire area BLD111 of the first block BLK11 among the multiple blocks BLK11 to BLK34 is in a display state, the partial areas BLD121 to BLD341 of the remaining blocks BLK12 to BLK34 are in a display state, and the remaining areas of the remaining blocks BLK12 to BLK34 are in a non-display state. The camera CAM can measure the first brightness distribution BLD1 in this state. In the step of measuring the first brightness distribution BLD1, the entire area BLD111 of the first block BLK11 can display white, and the multiple partial areas BLD121 to BLD341 of the remaining blocks BLK12 to BLK34 can display white.

[0074] Because the entire area BLD111 of the first block BLK11 displays white, the maximum voltage drop due to the first block BLK11 may occur. Accordingly, in the first brightness distribution BLD1, the voltage drop generated by the first block BLK11 (or the remaining area of ​​the first block BLK11) can be reflected in the brightness of the multiple partial areas BLD121 to BLD341 of the other blocks BLK12 to BLK34. In addition, in the first brightness distribution BLD1, the voltage drop generated by the first block BLK11 (or the remaining area of ​​the first block BLK11) can be reflected in the brightness of the partial areas of the first block BLK11.

[0075] When the entire area BLD122 of the second block BLK12 among the multiple blocks BLK11 to BLK34 is in the display state, the multiple partial areas BLD112, ..., and BLD342 of the remaining blocks BLK11 and BLK13 to BLK34 are also in the display state, and the remaining areas of the remaining blocks BLK11 and BLK13 to BLK34 are in the non-display state. In this state, the camera CAM can measure the second brightness distribution BLD2. During the step of measuring the second brightness distribution BLD2, the entire area BLD122 of the second block BLK12 can display white, and the multiple partial areas BLD112, ..., and BLD342 of the remaining blocks BLK11 and BLK13 to BLK34 can display white.

[0076] Since the entire area BLD122 of the second block BLK12 displays white, the maximum voltage drop due to the second block BLK12 may occur. Accordingly, in the second brightness distribution BLD2, the voltage drop generated by the second block BLK12 (or the remaining area of ​​the second block BLK12) can be reflected in the brightness of the plurality of partial areas BLD112, ... and BLD342 of the remaining blocks BLK11 and BLK13 to BLK34. In addition, in the second brightness distribution BLD2, the voltage drop generated by the second block BLK12 (or the remaining area of ​​the second block BLK12) can be reflected in the brightness of the partial areas of the second block BLK12.

[0077] The camera CAM may repeat this process as many times as the number of blocks BLK11 to BLK34 to measure multiple brightness distributions BLD1 to BLDp. For example, when the entire area (e.g., BLD34p) of the pth block (e.g., block BLK34) among the multiple blocks BLK11 to BLK34 is in the display state, the multiple partial areas BLD11p, BLD12p, ... of the remaining blocks BLK11 to BLK33 are in the display state, and the remaining areas of the remaining blocks BLK11 to BLK33 are in the non-display state. In this state, the camera CAM may measure the pth brightness distribution BLDp. In this case, p may be an integer greater than 1 and equal to the total number of blocks.

[0078] Next, the external calculation device may calculate a difference between the first reference luminance distribution BLDr and the first luminance distribution BLD1 as a first block luminance distribution, and store the calculated first block luminance distribution in the block luminance distribution storage unit 151. The first block luminance distribution may include luminance drop amounts generated in a plurality of blocks when the first block BLK11 emits light at a maximum grayscale.

[0079] Similarly, the external computing device may calculate the difference between the first reference luminance distribution BLDr and the second luminance distribution BLD2 as the second block luminance distribution, and store the calculated second block luminance distribution in the block luminance distribution storage unit 151. The second block luminance distribution may include the amount of luminance drop generated in the plurality of blocks when the second block BLK12 emits light at the maximum grayscale. The external computing device may repeat this process as many times as the number of the plurality of blocks BLK11 to BLK34 to store p block luminance distributions in the block luminance distribution storage unit 151.

[0080] The block current calculator 152 may calculate a plurality of block currents BLC11 to BLC34 (refer to Figure 7 and Figure 8 Each of the plurality of block currents BLC11 to BLC34 may be the sum of the drive currents that are expected to flow through the light emitting diodes of the pixels included in each of the plurality of blocks BLK11 to BLK34. For example, the block current BLC11 may be the sum of the drive currents that are expected to flow through the light emitting diodes of the pixels included in the block BLK11.

[0081] Reference Figure 7 , shows an exemplary input image composed of input grayscales GVi. It is expected that a relatively large drive current will flow to the light-emitting diodes in the bright part of the input image, and a relatively small drive current will flow to the light-emitting diodes in the dark part of the input image. Figure 7 and Figure 8 , expectations and Figure 7 The block current BLC12 of the block BLK12 corresponding to the bright part of the input image is large, and it is expected to be Figure 7 The block current BLC23 of the block BLK23 corresponding to the dark portion of the input image is small.

[0082] In an embodiment, the block current calculator 152 may calculate the expected plurality of block currents BLC11 to BLC34 by summing the plurality of input grayscales GVi corresponding to each of the plurality of blocks BLK11 to BLK34 or by calculating the average value of the plurality of input grayscales GVi corresponding to each of the plurality of blocks BLK11 to BLK34. For example, the block current calculator 152 may calculate the block current BLC11 by summing the plurality of input grayscales GVi of the pixels included in the block BLK11 or by calculating the average value of the plurality of input grayscales GVi of the pixels included in the block BLK11.

[0083] In another embodiment, the block current calculator 152 may multiply the plurality of input grayscales GVi corresponding to each of the plurality of blocks BLK11 to BLK34 by a weight to convert the plurality of input grayscales GVi into a current domain, and sum or average the plurality of input grayscales GVi in the current domain to calculate the desired plurality of block currents BLC11 to BLC34. For example, the block current calculator 152 may multiply the plurality of input grayscales GVi of the pixels included in the block BLK11 by a weight to convert the plurality of input grayscales GVi into a current domain, and sum or average the plurality of input grayscales GVi in the current domain to calculate the block current BLC11.

[0084] In another embodiment, the block current calculator 152 may convert the plurality of input grayscales GVi corresponding to each of the plurality of blocks BLK11 to BLK34 into the current domain by referring to a lookup table, and sum or average the plurality of input grayscales GVi of the current domain to calculate the desired plurality of block currents BLC11 to BLC34. For example, the block current calculator 152 may convert the plurality of input grayscales GVi of the pixels included in the block BLK11 into the current domain by referring to a lookup table, and sum or average the plurality of input grayscales GVi of the current domain to calculate the block current BLC11.

[0085] The brightness drop calculator 153 may scale each of the plurality of block brightness distributions BLD in accordance with the magnitude of each of the plurality of block currents BLC. The brightness drop calculator 153 may scale the block brightness distributions BLD to be smaller as the block brightness distribution of the block current BLC becomes smaller. Scaling may be performed by multiplying each of the plurality of block brightness distributions BLD by a scaling factor corresponding to the block brightness distributions BLD.

[0086] Since the plurality of block brightness distributions BLD stored in the block brightness distribution storage unit 151 correspond to a case where a maximum voltage drop occurs in each of the plurality of blocks, the scaling factor may have a range of 0 to 1. For example, the maximum scaling factor may be applied to the block brightness distribution of the block BLK12 having the maximum block current BLC12. When the block BLK12 displays white grayscale, the scaling factor 1 may be applied. For example, the minimum scaling factor may be applied to the block brightness distribution of the block BLK23 having the minimum block current BLC23. When the block BLK23 displays black grayscale, the scaling factor 0 may be applied.

[0087] The brightness drop amount calculator 153 may generate a total brightness distribution by summing the scaled block brightness distributions. Accordingly, the voltage drop amounts generated in all of the plurality of blocks BLK11 to BLK34 may be reflected in the brightness drop amount of each of the plurality of blocks in the total brightness distribution.

[0088] The luminance drop calculator 153 may interpolate the total luminance distribution to calculate the luminance drop amounts PLD of the plurality of pixels. For example, the luminance drop amounts PLD of the plurality of pixels may be calculated by performing bilinear interpolation between the luminance drops of adjacent blocks. The interpolation may be linear interpolation or nonlinear interpolation.

[0089] The luminance domain converter 154 may convert the plurality of input grayscales GVi into a plurality of input luminances LVi of the luminance domain. For example, the luminance domain converter 154 may apply a gamma curve to the plurality of input grayscales GVi to convert the plurality of input grayscales GVi into a plurality of input luminances LVi. Figure 10 , gamma curves when the gamma values ​​gm are 1.0, 2.2, and 2.8 are shown as examples.

[0090] The compensation value calculator 155 can calculate a compensation value CV based on the input luminance LVi and the luminance drop amount PLD. For example, the compensation value calculator 155 can calculate the compensation value CV based on the ratio of each of the plurality of luminance drop amounts PLD to each of the plurality of input luminances LVi. For example, as the ratio of the luminance drop amount PLD to the input luminance LVi in a pixel increases, the compensation value calculator 155 can calculate a larger compensation value for that pixel. For example, when the input luminance of pixel PXij is 100 nits and the luminance drop amount is 5 nits, the ratio of the luminance drop amount of pixel PXij to the input luminance may be 5 percent (%). In this case, since relatively large compensation is required, the compensation value calculator 155 may generate a compensation value for (+) 7 grayscale levels. For example, when the input luminance of pixel PXij is 500 nits and the luminance drop amount is 5 nits, the ratio of the luminance drop amount of pixel PXij to the input luminance may be 1%. In this case, since relatively small compensation is required, the compensation value calculator 155 may generate a compensation value for (+) 1 grayscale level.

[0091] According to an embodiment, the compensation value calculator 155 may apply an inverse gamma curve when generating the compensation value CV. For example, when generating the compensation value CV, the compensation value calculator 155 may apply an inverse gamma curve based on the gamma value gm of the luminance domain converter 154.

[0092] The output grayscale calculator 156 may calculate the output grayscale GVo by summing the input grayscale GVi and the compensation value CV.

[0093] Accordingly, according to this embodiment, the compensation value CV is not calculated based on the internal resistance calculated in the display device 10 and the voltage drop according to Ohm's law, but can be calculated based on the brightness drop actually measured in the display device 10. Therefore, the mura display problem can be effectively solved.

[0094] Figure 11 is a diagram for explaining a method for measuring luminance distribution according to another embodiment of the present invention.

[0095] Reference Figure 11 ,and Figure 6 Unlike the case of BLK11 , partial areas of the plurality of blocks BLK11 to BLK34 display colors other than white.

[0096] For example, in the step of measuring the first reference luminance distribution BLDr′, the plurality of partial regions BLD11r′ and BLD12r′ to BLD34r′ of the plurality of blocks BLK11 to BLK34 may display a first color (eg, red).

[0097] In the step of measuring the first brightness distribution BLD1 ′, the partial area BLD111 ′ of the first block BLK11 may display the first color, the remaining area of ​​the first block BLK11 may display white, and the partial areas BLD121 ′ to BLD341 ′ of the remaining blocks BLK12 to BLK34 may display the first color.

[0098] During the step of measuring the second brightness distribution BLD2', partial area BLD122' of the second block BLK12 may display the first color, the remaining area of ​​the second block BLK12 may display white, and the plurality of partial areas BLD112', ..., and BLD342' of the remaining blocks BLK11 and BLK13 to BLK34 may display the first color. In this manner, p brightness distributions of the first color may be measured. For example, during the step of measuring the p-th brightness distribution BLDp', the plurality of partial areas BLD11p', BLD12p', ..., and BLD34p' of the plurality of blocks BLK11 to BLK34 may display the first color. In this case, p may be an integer greater than 1 and equal to the total number of blocks.

[0099] In an embodiment, for example, in the step of measuring the first reference brightness distribution BLDr', the step of measuring the first brightness distribution BLD1', and the step of measuring the second brightness distribution BLD2', only pixels of the first color among the pixels included in the multiple partial areas emit light, and pixels of the remaining colors do not emit light, so that the multiple partial areas can display the first color.

[0100] According to this embodiment, the block luminance distribution based on the first reference luminance distribution BLDr', the first luminance distribution BLD1', and the second luminance distribution BLD2' may be used to accurately calculate the luminance drop amount PLD of the display device 10 when displaying the first color.

[0101] As reference Figure 2 As described, the pixels of pixel unit 14 may correspond to any one of a first color, a second color (eg, green), and a third color (eg, blue). Therefore, block luminance distributions for the second and third colors may be additionally required.

[0102] For example, the method for measuring luminance distribution may further include measuring a second reference luminance distribution when a partial area of ​​each of the plurality of blocks BLK11 to BLK34 displays the second color and the remaining area of ​​each of the plurality of blocks BLK11 to BLK34 is in a non-display state.

[0103] In addition, the method for measuring brightness distribution may further include: measuring a third brightness distribution when a partial area of ​​the first block BLK11 displays the second color, the remaining area of ​​the first block BLK11 displays white, partial areas of the remaining blocks BLK12 to BLK34 display the second color, and the remaining areas of the remaining blocks BLK12 to BLK34 are in a non-display state.

[0104] Additionally, the method for measuring brightness distribution may further include measuring a fourth brightness distribution when a portion of the second block BLK12 displays the second color, the remaining portion of the second block BLK12 displays white, portions of the remaining blocks BLK11 and BLK13 to BLK34 display the second color, and the remaining portions of the remaining blocks BLK11 and BLK13 to BLK34 are in a non-display state. Here, the "third" and "fourth" brightness distributions for the second color are designated for the sole purpose of distinguishing between the first brightness distribution BLD1' and the second brightness distribution BLD2' for the first color. In this manner, p brightness distributions for the second color may be measured. In this case, p may be an integer greater than 1 and equal to the total number of blocks.

[0105] For example, in the step of measuring the second reference brightness distribution, the step of measuring the third brightness distribution, and the step of measuring the fourth brightness distribution, only the pixels of the second color among the pixels included in the multiple partial areas emit light, and the pixels of the remaining colors do not emit light, so that the multiple partial areas can display the second color.

[0106] The block luminance distribution for the third color can also be calculated in a similar manner to that described above, and therefore repeated description will be omitted.

[0107] In another embodiment, when generating the block luminance distribution, portions of the plurality of blocks BLK11 to BLK34 may display gray instead of white. Assuming an ideal luminance contribution ratio of 1:1:1 for red, green, and blue, white may be composed of 255 grayscales of red, 255 grayscales of green, and 255 grayscales of blue. Gray may be composed of q grayscales of red, q grayscales of green, and q grayscales of blue. For example, q may be an integer greater than 0 and less than 255. Black may be composed of 0 grayscales of red, 0 grayscales of green, and 0 grayscales of blue.

[0108] According to this embodiment, the luminance drop amount PLD of the intermediate grayscale and the white corresponding to the highest grayscale can be accurately calculated.

[0109] The display device and the method for measuring brightness distribution according to the present invention can effectively solve the mura display problem by reflecting the brightness reduction amount during actual display.

[0110] The accompanying drawings and the detailed description of the present invention referred to so far are merely illustrative of the present invention. It will be understood that the present invention is disclosed for illustrative purposes only and is not intended to limit the scope of the present invention. Therefore, it will be understood by those skilled in the art that various modifications and equivalent embodiments may be made without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical concepts of the appended claims.

Claims

1. A method for measuring brightness distribution of a display device, the display device including a plurality of pixels divided into a plurality of blocks, the method comprising: measuring a first reference luminance distribution when a partial area of ​​each of the plurality of blocks is in a display state and a remaining area of ​​each of the plurality of blocks is in a non-display state; measuring a first luminance distribution when an entire area of ​​a first block among the plurality of blocks is in the display state, the partial area of ​​each of a first plurality of remaining blocks is in the display state, and the remaining area of ​​each of the first plurality of remaining blocks is in the non-display state, wherein the first plurality of remaining blocks are the plurality of blocks excluding the first block; and A second luminance distribution is measured when the entire area of ​​a second block among the plurality of blocks is in the display state, the partial area of ​​each of a second plurality of remaining blocks is in the display state, and the remaining area of ​​each of the second plurality of remaining blocks is in the non-display state, wherein the second plurality of remaining blocks are the plurality of blocks other than the second block.

2. The method according to claim 1, wherein The remaining area is larger than the partial area.

3. The method according to claim 1, wherein When the first reference luminance distribution is measured, the partial area of ​​each of the plurality of blocks displays white, wherein, when measuring the first brightness distribution, the entire area of ​​the first block appears white, and the partial area of ​​each of the first plurality of remaining blocks appears white, and Wherein, when the second luminance distribution is measured, the entire area of ​​the second block appears white, and the partial area of ​​each of the second plurality of remaining blocks appears white.

4. The method according to claim 1, wherein When the first reference luminance distribution is measured, the partial area of ​​each of the plurality of blocks displays a first color, wherein, when measuring the first brightness distribution, the partial area of ​​the first block displays the first color, the remaining area of ​​the first block displays white, and the partial area of ​​each of the first plurality of remaining blocks displays the first color, and Wherein, when measuring the second brightness distribution, the partial area of ​​the second block displays the first color, the remaining area of ​​the second block displays white, and the partial area of ​​each of the second plurality of remaining blocks displays the first color.

5. The method according to claim 4, further comprising: measuring a second reference luminance distribution when the partial area of ​​each of the plurality of blocks displays a second color and the remaining area of ​​each of the plurality of blocks is in the non-display state; measuring a third luminance distribution when the partial area of ​​the first block displays the second color, the remaining area of ​​the first block displays white, the partial area of ​​each of the first plurality of remaining blocks displays the second color, and the remaining area of ​​each of the first plurality of remaining blocks is in the non-display state; as well as A fourth luminance distribution is measured when the partial area of ​​the second block displays the second color, the remaining area of ​​the second block displays white, the partial area of ​​each of the second plurality of remaining blocks displays the second color, and the remaining area of ​​each of the second plurality of remaining blocks is in the non-display state.

6. The method according to claim 5, wherein: In measuring the first reference luminance distribution, measuring the first luminance distribution, and measuring the second luminance distribution, the partial area displays the first color by emitting pixels of the first color among a plurality of pixels included in the partial area and not emitting pixels of colors other than the first color, and Wherein, in measuring the second reference brightness distribution, measuring the third brightness distribution and measuring the fourth brightness distribution, the partial area displays the second color by emitting pixels of the second color among the multiple pixels included in the partial area and not emitting pixels of the remaining colors except the second color.

7. The method according to claim 1, further comprising: storing a difference between the first reference luminance distribution and the first luminance distribution as a first block luminance distribution; as well as A difference between the first reference luminance distribution and the second luminance distribution is stored as a second block luminance distribution.

8. A display device comprising: Multiple pixels are divided into multiple blocks; as well as A grayscale converter converts a plurality of input grayscales for the plurality of pixels into a plurality of output grayscales, wherein each of the plurality of blocks includes at least two pixels of the plurality of pixels, wherein the grayscale converter generates the plurality of output grayscales based on a plurality of block currents calculated from the plurality of input grayscales and a plurality of pre-stored block luminance distributions, wherein the block brightness distribution is calculated based on the difference between the first reference brightness distribution and the corresponding brightness distribution, wherein the first reference luminance distribution is measured when a partial area of ​​each of the plurality of blocks is in a display state and a remaining area of ​​each of the plurality of blocks is in a non-display state, and wherein the corresponding brightness distribution is measured when the entire area of ​​a corresponding block among the multiple blocks is in the display state, the partial area of ​​each of the multiple remaining blocks except the corresponding block is in the display state, and the remaining area of ​​each of the multiple remaining blocks is in the non-display state.

9. The display device according to claim 8, wherein The grayscale converter includes a luminance drop amount calculator that scales each of the plurality of block luminance distributions corresponding to a magnitude of each of the plurality of block currents. The brightness drop amount calculator scales the plurality of block brightness distributions, and when the block current corresponding to the block brightness distribution is smaller, the brightness drop amount calculator scales the block brightness distribution to a smaller value. wherein the brightness drop amount calculator generates a total brightness distribution by summing the scaled brightness distributions of the plurality of blocks, and The brightness drop calculator interpolates the total brightness distribution to calculate a plurality of brightness drop amounts of the plurality of pixels.

10. The display device according to claim 9, wherein The grayscale converter further includes a brightness domain converter, which converts the plurality of input grayscales into a plurality of input brightnesses in a brightness domain. The grayscale converter further includes a compensation value calculator, which calculates a plurality of compensation values ​​based on the plurality of input luminances and the plurality of luminance drop amounts. wherein the compensation value calculator calculates the plurality of compensation values ​​according to a ratio of each of the plurality of brightness drop amounts to each of the plurality of input brightnesses, and The grayscale converter further includes an output grayscale calculator, which sums the multiple input grayscales and the multiple compensation values ​​to calculate the multiple output grayscales.

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