Gamma correction method for a display device

Abstract

The gamma correction method for a display device relates to a gamma correction method for a display device that performs gamma correction for a low grayscale, wherein a first driving current is measured according to a first grayscale voltage corresponding to the low grayscale, a predicted brightness is determined based on a driving current-luminance relationship table and the first driving current, the predicted brightness is compared with a first target brightness for the low grayscale, and if the predicted brightness and the first target brightness are different, a first offset value is determined based on the first driving current and the first target brightness, and the first grayscale voltage is corrected based on the first offset value. That is, the gamma correction method for a display device performs gamma correction for the low grayscale by measuring the driving current, and accordingly, the process time for gamma correction can be shortened compared to when gamma correction for the low grayscale is performed by measuring the brightness.

Description

Technology Field

[0001] The present invention relates to a display device. More specifically, it relates to a gamma correction method for a display device. Background Technology

[0002] Generally, a display device includes a display panel, a gate driver, a source driver, and a timing controller. The display panel includes a plurality of gate lines, a plurality of data lines, and a plurality of pixels electrically connected to the plurality of gate lines and the plurality of data lines. The gate driver provides gate signals to the gate lines, the source driver provides data voltages to the data lines, and the timing controller controls the gate driver and the source driver.

[0003] If the image quality of a finished product fails to meet the target value due to variations in the manufacturing process or other factors, the product may be deemed defective. Since discarding all finished products that do not meet the target image quality results in a significant decrease in yield, it is required to post-correct the image quality of the display device to meet the target value. Accordingly, to match the image quality of the display device to the target value, gamma correction may be performed to enable the display device to have gamma characteristics corresponding to the target gamma value.

[0004] Gamma correction is a process in which a display device accurately adjusts the luminance of each grayscale level to a target luminance. Conventional gamma correction requires measuring the luminance of each grayscale level multiple times. In the case of low grayscale levels, there is a problem in that the luminance measurement time increases and the accuracy of gamma correction decreases due to the performance limitations of the light-receiving elements inside the luminance meter. The problem to be solved

[0005] One objective of the present invention is to provide a gamma correction method for a display device that measures the driving current and performs gamma correction for low grayscale.

[0006] However, the problem to be solved by the present invention is not limited to the problem mentioned above, and may be expanded in various ways without departing from the spirit and scope of the present invention. means of solving the problem

[0007] To achieve the objective of the present invention, a gamma correction method for a display device according to embodiments of the present invention may include the steps of: measuring a first driving current according to a first grayscale voltage corresponding to a low grayscale; determining a predicted brightness based on a driving current-brightness relationship table and the first driving current; comparing the predicted brightness with a first target brightness for the low grayscale; determining a first offset value based on the first driving current and the first target brightness when the predicted brightness and the first target brightness are different; and correcting the first grayscale voltage based on the first offset value.

[0008] In one embodiment, the method may further include the steps of: measuring a luminance according to a second grayscale voltage corresponding to a high grayscale; comparing the luminance according to the second grayscale voltage with a second target luminance for the high grayscale; determining a second offset value based on the luminance according to the second grayscale voltage and the second target luminance when the luminance according to the second grayscale voltage and the second target luminance are different; and correcting the second grayscale voltage based on the second offset value.

[0009] In one embodiment, when the predicted brightness matches the first target brightness, the step of no longer correcting the first grayscale voltage may be further included.

[0010] In one embodiment, the steps of measuring the first driving current, determining the predicted brightness, comparing, determining the first offset value, and correcting the first grayscale voltage may be repeated until the predicted brightness matches the first target brightness.

[0011] In one embodiment, the step of measuring the luminance according to the first grayscale voltage once is further included, and the driving current-luminance relationship table may include the luminance according to the first grayscale voltage.

[0012] In one embodiment, the step of determining the first offset value may include the step of determining a target current using the driving current-luminance relationship table and the first target luminance, the step of determining a target grayscale voltage using the driving current-grayscale voltage relationship, the first driving current, and the target current, and the step of determining the first offset value by subtracting the first grayscale voltage from the target grayscale voltage.

[0013] In one embodiment, the driving current-gradation voltage relationship can be updated according to the first driving current.

[0014] In one embodiment, the method further includes the steps of separately driving each panel block of a display panel to measure the first driving current for each of the panel blocks according to the first grayscale voltage, and calculating the deviation of the first driving current according to the position of each of the panel blocks, wherein the target grayscale voltage may be determined differently for each position of the display panel according to the deviation of the first driving current.

[0015] In one embodiment, the method further comprises the steps of separately driving an area of ​​the display panel excluding each panel block of the display panel to measure the first driving current for the area of ​​the display panel excluding each panel block according to the first grayscale voltage, and calculating a deviation of the first driving current according to the position of each panel block, wherein the target grayscale voltage may be determined differently for each position of the display panel according to the deviation of the first driving current.

[0016] In one embodiment, the correction of the first grayscale voltage can be performed by adding the first offset value to the first grayscale voltage.

[0017] In one embodiment, the first driving current is measured by a current measuring unit connected to a power line to which a power supply voltage is applied, and the power supply voltage can be applied to a display panel through the power line.

[0018] To achieve another objective of the present invention, a gamma correction method for a display device according to embodiments of the present invention may include the steps of: measuring a first driving current N times according to a grayscale voltage corresponding to a low grayscale; calculating an average value of the first driving current measured N times; determining a predicted brightness based on a driving current-luminance relationship table and the average value of the first driving current; comparing the predicted brightness with a first target brightness for the low grayscale; if the predicted brightness and the first target brightness are different, determining a first offset value based on the average value of the first driving current and the first target brightness; and correcting the first grayscale voltage based on the first offset value (N is a positive integer greater than or equal to 2).

[0019] In one embodiment, the method may further include the steps of: measuring a luminance according to a second grayscale voltage corresponding to a high grayscale; comparing the luminance according to the second grayscale voltage with a second target luminance for the high grayscale; determining a second offset value based on the luminance according to the second grayscale voltage and the second target luminance when the luminance according to the second grayscale voltage and the second target luminance are different; and correcting the second grayscale voltage based on the second offset value.

[0020] In one embodiment, the step of measuring the luminance according to the first grayscale voltage once is further included, and the driving current-luminance relationship table may include the luminance according to the first grayscale voltage.

[0021] In one embodiment, the step of determining the first offset value may include the step of determining a target current using the driving current-luminance relationship table and the first target luminance, the step of determining a target grayscale voltage using the driving current-grayscale voltage relationship, the average value of the first driving current, and the target current, and the step of determining the first offset value by subtracting the first grayscale voltage from the target grayscale voltage.

[0022] In one embodiment, the driving current-gradation voltage relationship can be updated according to the first driving current.

[0023] In one embodiment, the method further includes the steps of separately driving each panel block of a display panel to measure the first driving current for each of the panel blocks according to the first grayscale voltage, and calculating the deviation of the first driving current according to the position of each of the panel blocks, wherein the target grayscale voltage may be determined differently for each position of the display panel according to the deviation of the first driving current.

[0024] In one embodiment, the method further comprises the steps of separately driving an area of ​​the display panel excluding each panel block of the display panel to measure the first driving current for the area of ​​the display panel excluding each panel block according to the first grayscale voltage, and calculating a deviation of the first driving current according to the position of each panel block, wherein the target grayscale voltage may be determined differently for each position of the display panel according to the deviation of the first driving current.

[0025] In one embodiment, the correction of the first grayscale voltage can be performed by adding the first offset value to the first grayscale voltage.

[0026] In one embodiment, the first driving current is measured by a current measuring unit connected to a power line to which a power supply voltage is applied, and the power supply voltage can be applied to a display panel through the power line. Effects of the invention

[0027] A gamma correction method for a display device according to embodiments of the present invention measures a first driving current corresponding to a first grayscale voltage corresponding to a low grayscale, determines a predicted brightness based on a driving current-brightness relationship table and the first driving current, compares the predicted brightness with a first target brightness for the low grayscale, and if the predicted brightness and the first target brightness are different, determines a first offset value based on the first driving current and the first target brightness, and corrects the first grayscale voltage based on the first offset value, thereby enabling gamma correction for the low grayscale by measuring the driving current. Accordingly, the process time for gamma correction can be shortened compared to when gamma correction for the low grayscale is performed by measuring the brightness.

[0028] However, the effects of the present invention are not limited to the effects described above and may be extended in various ways without departing from the spirit and scope of the present invention. Brief explanation of the drawing

[0029] FIG. 1 is a flowchart illustrating a gamma correction method for a display device according to embodiments of the present invention. FIG. 2 is a block diagram showing an example of a display device according to the gamma correction method of the display device of FIG. 1. FIG. 3 is a block diagram showing an example of a pixel according to the gamma correction method of the display device of FIG. 1. Figure 4 is a table showing an example of a driving current-luminance relationship table according to the gamma correction method of the display device of Figure 1. FIG. 5 is a diagram showing an example of gamma correction being performed according to the gamma correction method of the display device of FIG. 1. Figure 6 is a flowchart illustrating a gamma correction method for the display device of Figure 1. FIG. 7 is a diagram showing panel blocks of a gamma correction method of a display device according to embodiments of the present invention. FIG. 8 is a drawing showing panel blocks of a gamma correction method of a display device according to embodiments of the present invention. FIG. 9 is a flowchart illustrating a gamma correction method for a display device according to embodiments of the present invention. FIG. 10 is a block diagram showing an electronic device according to embodiments of the present invention. Figure 11 is a diagram showing an example in which the electronic device of Figure 10 is implemented as a smartphone. Specific details for implementing the invention

[0030] Hereinafter, the present invention will be described in more detail with reference to the attached drawings.

[0031] FIG. 1 is a flowchart illustrating a gamma correction method for a display device according to embodiments of the present invention, FIG. 2 is a block diagram illustrating an example of a display device (1000) according to the gamma correction method of FIG. 1, and FIG. 3 is a block diagram illustrating an example of a pixel (P) according to the gamma correction method of the display device of FIG. 1.

[0032] Referring to FIG. 1, the gamma correction method of the display device of FIG. 1 measures a first driving current according to a first grayscale voltage corresponding to a low grayscale (S110), determines a predicted brightness based on a driving current-brightness relationship table and the first driving current (S120), compares the predicted brightness with a first target brightness for the low grayscale (S130), and if the predicted brightness and the first target brightness are different, determines a first offset value based on the first driving current and the first target brightness (S140), and corrects the first grayscale voltage based on the first offset value (S150). The gamma correction method of the display device of FIG. 1 may not further correct the first grayscale voltage if the predicted brightness and the first target brightness match. The gamma correction method of the display device of FIG. 1 may repeat the measurement of a first driving current, the determination of a predicted brightness, the comparison of the predicted brightness with a first target brightness, the determination of a first offset value, and the correction of a first grayscale voltage until the predicted brightness and the first target brightness match. A detailed explanation thereof will be provided later.

[0033] Referring to FIG. 2, the display device (1000) may include a display panel (100), a timing controller (200), a gate driver (300), a source driver (400), a power voltage supply unit (500), and a current measuring unit (600). In one embodiment, the timing controller (200) and the source driver (400) may be integrated on a single chip.

[0034] The display panel (100) may include a display portion (AA) for displaying images and a peripheral portion (PA) positioned adjacent to the display portion (AA). In one embodiment, a gate driver (300) may be integrated in the peripheral portion (PA).

[0035] A display panel (100) may include a plurality of gate lines (GL), a plurality of data lines (DL), and a plurality of pixels (P) electrically connected to the gate lines (GL) and the data lines (DL). The gate lines (GL) may extend in a first direction (D1), and the data lines (DL) may extend in a second direction (D2) that intersects the first direction (D1).

[0036] The timing controller (200) can receive input image data (IMG) and input control signals (CONT) from a host processor (e.g., a graphic processing unit (GPU), etc.). For example, the input image data (IMG) may include red image data, green image data, and blue image data. In one embodiment, the input image data (IMG) may further include white image data. In another example, the input image data (IMG) may include magenta image data, yellow image data, and cyan image data. The input control signals (CONT) may include a master clock signal and a data enable signal. The input control signals (CONT) may further include a vertical synchronization signal and a horizontal synchronization signal.

[0037] The timing controller (200) can generate a first control signal (CONT1), a second control signal (CONT2), and a data signal (DATA) based on input image data (IMG) and an input control signal (CONT).

[0038] The timing controller (200) can generate a first control signal (CONT1) to control the operation of the gate driver (300) based on an input control signal (CONT) and output it to the gate driver (300). The first control signal (CONT1) may include a vertical start signal and a gate clock signal.

[0039] The timing controller (200) can generate a second control signal (CONT2) to control the operation of the source driver (400) based on an input control signal (CONT) and output it to the source driver (400). The second control signal (CONT2) may include a horizontal start signal and a load signal.

[0040] The timing controller (200) can receive input image data (IMG) and an input control signal (CONT) to generate a data signal (DATA). The timing controller (200) can output the data signal (DATA) to the source driver (400).

[0041] The gate driver (300) can generate gate signals to drive gate lines (GL) in response to a first control signal (CONT1) received from the timing controller (200). The gate driver (300) can output the gate signals to the gate lines (GL). For example, the gate driver (300) can output the gate signals to the gate lines (GL) sequentially.

[0042] The source driver (400) can receive a second control signal (CONT2) and a data signal (DATA) from the timing controller (200). The source driver (400) can generate data voltages by converting the data signal (DATA) into an analog voltage. The source driver (400) can output the data voltages to the data line (DL).

[0043] The power voltage generating unit (500) can generate a power voltage and provide it to the display panel (100). For example, the power voltage generating unit (600) can provide a first power voltage (ELVDD) and a second power voltage (ELVSS) to the display panel (100) that are applied to each of the pixels (P) including a light-emitting element. For example, the first power voltage (ELVDD) may be a high power voltage, and the second power voltage (ELVSS) may be a low power voltage.

[0044] The current measuring unit (600) is connected to a power line to which a power supply voltage is applied and can measure the driving current (IDATA) flowing through the pixel (P). For example, the current measuring unit (600) may be connected to a power line to which a first power supply voltage (ELVDD) is applied. As another example, the current measuring unit (600) may be connected to a power line to which a second power supply voltage (ELVSS) is applied.

[0045] Referring to FIGS. 2 and 3, each pixel (P) may include a driving transistor (DT) and a light-emitting element (EE). The driving transistor (DT) may include a control electrode to which a data voltage (VDATA) is applied, a first electrode to which a first power supply voltage (ELVDD) is applied, and a second electrode connected to the light-emitting element (EE). The light-emitting element (EE) may include an anode electrode connected to the driving transistor (DT) and a cathode electrode to which a second power supply voltage (ELVSS) is applied.

[0046] The source driver (400) can determine the data voltage (VDATA) according to the gradation voltage. For example, if the gradation voltage corresponding to 255 gradations is 20V, the data voltage (VDATA) for displaying 255 gradations may be 20V.

[0047] The driving current (IDATA) can be determined by the data voltage (VDATA) applied to the control electrode of the driving transistor (DT). For example, the driving current (IDATA) can increase as the data voltage (VDATA) increases.

[0048] When a driving current flows through a light-emitting element (EE), the light-emitting element (EE) can emit light. At this time, the brightness can increase as the driving current (IDATA) increases.

[0049] FIG. 4 is a table showing an example of a driving current-luminance relationship table (DLT) according to the gamma correction method of the display device of FIG. 1, and FIG. 5 is a diagram showing an example of gamma correction being performed according to the gamma correction method of the display device of FIG. 1.

[0050] Referring to FIGS. 1 to 5, the gamma correction method of the display device of FIG. 1 can measure (S110) a first driving current (IDATA1) according to a first grayscale voltage (VG1) corresponding to a low grayscale. The range of the low grayscale can be determined by the user. For example, if the grayscale has a value from 0 to 255, the 0 grayscale (0G) to the 20 grayscale (20G) can be determined as the low grayscale, and the 21 grayscale (21G) to the 255 grayscale (255G) can be determined as the high grayscale. Hereinafter, it is assumed that the low grayscale is from the 0 grayscale (0G) to the 20 grayscale (20G), and the high grayscale is from the 21 grayscale (21G) to the 255 grayscale (255G).

[0051] The first grayscale voltage (VG1) may be a grayscale voltage (VG) for displaying a low grayscale. For example, the first grayscale voltage (VG1) may be a grayscale voltage (VG) for displaying a grayscale between 0 grayscale (0G) and 20 grayscale (20G).

[0052] The first driving current (IDATA1) may be a driving current (IDATA) flowing to the pixel (P) when the first grayscale voltage (VG1) is applied to the pixel (P). For example, the first driving current (IDATA1) may be a driving current (IDATA) flowing to the pixel (P) when a grayscale between 0 grayscale (0G) and 20 grayscale (20G) is displayed.

[0053] The gamma correction method of the display device of FIG. 1 can determine the predicted luminance (PL) (S120) based on the driving current-luminance relationship table (DLT) and the first driving current (IDATA1). The gamma correction method of the display device of FIG. 1 can measure the luminance according to the first grayscale voltage (VG1) once. The driving current-luminance relationship table (DLT) may include the luminance according to the first grayscale voltage (VG1).

[0054] A driving current-luminance relationship table (DLT) can be used to predict the luminance to be displayed by the first driving current (IDATA) from the first driving current (IDATA1). Therefore, in the gamma correction method of the display device of FIG. 1, gamma correction for low grayscale does not require measuring the luminance for each grayscale multiple times.

[0055] The gamma correction method of the display device of FIG. 1 may measure the luminance according to the first grayscale voltage (VG1) only once to generate a driving current-luminance relationship table (DLT). For example, if the measured luminance is 10 nits when a driving current of 10 A flows through the pixel (P) in a single measurement, the driving current-luminance relationship table (DLT) may include a luminance of 10 nits corresponding to a driving current of 10 A (IDATA). Furthermore, driving current-luminance relationships that are not measured may be determined through the interpolation of the measured values. However, the gamma correction method of the display device other than the embodiments of this invention is not limited thereto. For example, the gamma correction method of the display device of FIG. 1 may measure the luminance according to the first grayscale voltage (VG1) two or more times.

[0056] The predicted luminance (PL) may be the luminance predicted from the first driving current (IDATA1) using a driving current-luminance relationship table (DLT). For example, if the driving current-luminance relationship table (DLT) includes a luminance of 10 nit corresponding to a driving current (IDATA) of 10 A, the predicted luminance (PL) generated from the first driving current (IDATA1) of 10 A may be 10 nit.

[0057] The gamma correction method of the display device of FIG. 1 can compare the predicted luminance (PL) with the first target luminance (TL1) for the low grayscale (S130). The first target luminance (TL1) for the low grayscale may be a luminance set so that the display device has gamma characteristics corresponding to the target gamma value in the low grayscale.

[0058] For example, gamma correction may be a process in which the maximum luminance is determined and the luminance of each gradation is corrected to have gamma characteristics corresponding to the target gamma value. For example, if the maximum luminance is determined to be 500 nits and the target gamma value is 2.2, the luminance of each gradation may be determined so that the luminance of 255 gradations becomes 500 nits and the gradation-luminance curve has a gamma value of 2.2. At this time, the determined luminance of the lower gradation may be the first target luminance (TL1).

[0059] The gamma correction method of the display device of FIG. 1 can determine a first offset value (OV1) based on a first driving current (IDATA1) and a first target brightness (TL1) when the predicted brightness (PL) and the first target brightness (TL1) are different (S140), and correct a first grayscale voltage based on the first offset value (OV1) (S150). The gamma correction method of the display device of FIG. 1 can determine a target current (TC) using a driving current-brightness relationship table (DLT) and a first target brightness (TL1), determine a target grayscale voltage (TVG) using a driving current-grayscale voltage relationship, a first driving current (IDATA1), and a target current (TC), and determine a first offset value (OV1) by subtracting a first grayscale voltage (VG1) from the target grayscale voltage (TVG). Correction of the first grayscale voltage (VG1) can be performed by adding a first offset value (OV1) to the first grayscale voltage (VG1).

[0060] The target current (TC) may be a driving current (IDATA) flowing through a pixel (P) to display a first target luminance (TL1). Just as the gamma correction method of the display device of FIG. 1 determined the predicted luminance (PL) from the first driving current (IDATA1) using a driving current-luminance relationship table (DLT), the target current (TC) can be determined from the first target luminance (TL1) using a driving current-luminance relationship table (DLT).

[0061] The target grayscale voltage (TVG) may be a grayscale voltage (VG) that causes the target current (TC) to flow through the pixel (P). To determine the target grayscale voltage (TVG), a driving current-grayscale voltage relationship may be used. In one embodiment, the driving current-grayscale voltage relationship may be updated according to the first driving current (IDATA1).

[0062] For example, the initial driving current-grayscale voltage relationship can represent the ideal relationship between the driving current (IDATA) and the grayscale voltage (VG) (i.e., the relationship between the driving current (IDATA) and the data voltage (VDATA). For example, the initial driving current-grayscale voltage relationship It may be. Here, IDATA may be the driving current and VG may be the grayscale voltage. However, since there are various external factors that affect the relationship between the driving current (IDATA) and the grayscale voltage (VG), the driving current-grayscale voltage relationship equation can be updated to correspond to reality through data on the relationship between the driving current (IDATA) and the grayscale voltage (VG) accumulated as the first driving current (IDATA1) is measured.

[0063] The first offset value (OV1) can be added to the first grayscale voltage (VG1) so that the first grayscale voltage (VG1) becomes the target grayscale voltage (TVG). However, since the first offset value (OV1) is determined using a value predicted through the driving current-luminance relationship table (DLT) and the driving current-grayscale voltage relationship equation, the first grayscale voltage (VG1) and the target grayscale voltage (TVG) may not be matched in a single gamma correction. Accordingly, the gamma correction method of the display device of FIG. 1 may repeat the measurement of the first driving current (IDATA1), the determination of the predicted luminance (PL), the comparison of the predicted luminance (PL) with the first target luminance (TL1), the determination of the first offset value (OV1), and the correction of the first grayscale voltage (VG1) until the predicted luminance (PL) and the first target luminance (TL1) match. That is, the gamma correction method of the display device of FIG. 1 may no longer correct the first grayscale voltage (VG1) when the predicted luminance (PL) matches the first target luminance (TL1). A series of processes will be explained below through FIG. 5.

[0064] For example, when the first grayscale voltage (VG1) corresponding to the first 10 grayscales (10G) is 10V and a data voltage (VDATA) of 10V is applied, the driving current (IDATA) (i.e., the first driving current (IDATA1) according to the first grayscale voltage (VG1) corresponding to the 10 grayscales (10G)) is 10A, the driving current-luminance relationship table (DLT) is as shown in FIG. 4, and the driving current-grayscale voltage relationship equation is ..., and it is assumed that the first target luminance (TL1) for 10 gradations (10G) is 20 nits. In this case, the predicted luminance (PL) may be 10 nits, which is different from the first target luminance (TL1). Since the first target luminance (TL1) is 20 nits, the target current (TC) may be 20A. Since the first driving current (IDATA1) must be doubled to become the target current (TC), the target gradation voltage (TVG) is It can be. Therefore, the first offset value (OV1) is And, the first grayscale voltage (VG1) is It can be corrected as. And, Assuming that when the data voltage (VDATA) is applied, the driving current (IDATA) (i.e., the first driving current (IDATA1) corresponding to the first grayscale voltage (VG1) corresponding to the corrected 10 grayscales (10G)) is 20A, the predicted luminance (PL) may be 20 nits, which is the same as the first target luminance (TL1). Therefore, the gamma correction method of the display device of FIG. 1 may no longer correct the first grayscale voltage (VG1).

[0065] Since the display device according to the embodiments is substantially identical to the configuration of the display device (1000) of FIG. 1, except for the error correction code comparison unit (1240) and the sleep operation unit (1250), the same reference numbers and reference symbols are used for identical or similar components, and redundant descriptions are omitted.

[0066] Figure 6 is a flowchart illustrating a gamma correction method for the display device of Figure 1.

[0067] Referring to FIGS. 2, FIGS. 3, and FIGS. 6, the gamma correction method of the display device of FIG. 1 measures the brightness according to a second grayscale voltage corresponding to a high grayscale (S210), compares the brightness according to the second grayscale voltage with a second target brightness for the high grayscale (S220), determines a second offset value based on the brightness according to the second grayscale voltage and the second target brightness when the brightness according to the second grayscale voltage and the second target brightness are different (S230), and corrects the second grayscale voltage based on the second offset value (S240).

[0068] The second grayscale voltage may be a grayscale voltage for displaying high grayscale. For example, the second grayscale voltage may be a grayscale voltage for displaying grayscale between 21 and 255 grayscales.

[0069] The luminance according to the second grayscale voltage may be the luminance displayed when the second grayscale voltage is applied to the pixel (P). For example, the luminance according to the second grayscale voltage may be the luminance displayed when a grayscale between 21 and 255 is displayed.

[0070] The gamma correction method of the display device of FIG. 1 can compare the luminance according to the second grayscale voltage with the second target luminance for the high grayscale (S220). The second target luminance for the high grayscale (TL2) may be a luminance set so that the display device has gamma characteristics corresponding to the target gamma value in the high grayscale.

[0071] For example, gamma correction may be a process in which the maximum luminance is determined and the luminance of each gradation is corrected to have gamma characteristics corresponding to the target gamma value. For example, if the maximum luminance is determined to be 500 nits and the target gamma value is 2.2, the luminance of each gradation may be determined so that the luminance of 255 gradations becomes 500 nits and the gradation-luminance curve has a gamma value of 2.2. At this time, the determined luminance of the high gradation may be the second target luminance (TL2).

[0072] The gamma correction method of the display device of FIG. 1 determines a second offset value (S230) based on the brightness according to the second grayscale voltage and the second target brightness when the brightness according to the second grayscale voltage and the second target brightness are different, and corrects the second grayscale voltage (S240) based on the second offset value. The correction of the second grayscale voltage can be performed by adding the second offset value to the second grayscale voltage. For example, the absolute value of the second offset value may be larger as the difference between the brightness according to the second grayscale voltage and the second target brightness becomes larger. However, the gamma correction method of the display device of FIG. 1 may repeat the brightness measurement several times while changing the second offset value so that the brightness according to the second grayscale voltage becomes the second target brightness. Accordingly, the gamma correction method of the display device of FIG. 1 may repeat the measurement of luminance according to the second grayscale voltage, the comparison of luminance according to the second grayscale voltage with the second target luminance for high grayscale, the determination of the second offset value, and the correction of the second grayscale voltage until the luminance according to the second grayscale voltage matches the second target luminance. That is, the gamma correction method of the display device of FIG. 1 may not further correct the second grayscale voltage when the luminance according to the second grayscale voltage matches the second target luminance.

[0073] FIG. 7 is a drawing showing panel blocks (PB) of a gamma correction method of a display device according to embodiments of the present invention.

[0074] Since the gamma correction method of the display device according to the embodiments is substantially the same as the gamma correction method of the display device of FIG. 1, except for the determination of the target grayscale voltage, the same reference numbers and reference symbols are used for identical or similar components, and redundant descriptions are omitted.

[0075] Referring to FIGS. 2, FIGS. 3, and FIG. 7, the gamma correction method of the display device of FIG. 7 can separately drive each panel block (PB) of the display panel (100) to measure a first driving current for each panel block (PB) according to a first grayscale voltage, and calculate a deviation of the first driving current according to the position of each panel block (PB). The target grayscale voltage can be determined differently for each position of the display panel (100) according to the deviation of the first driving current.

[0076] Panel blocks (PB) may be areas in which the display panel (100) is divided into a certain size. Even if the same data voltage (VDATA) is applied to each panel block (PB), the driving current (IDATA) may differ depending on the location within the display panel (100) (i.e., a deviation in the first driving current may occur). Therefore, when determining the target grayscale voltage from the target current, it may be necessary to reflect the deviation in the first driving current.

[0077] For example, the deviation of the first driving current can be determined based on the first driving current measured by displaying a white gradation (e.g., 255 gradations) on each panel block (PB) and a black gradation (e.g., 0 gradations) on an area of ​​the display panel (100) excluding each panel block (PB). For example, the deviation of the first driving current can be determined based on the first driving current of the central panel block (PB). As another example, the deviation of the first driving current can be determined based on the average value of the first driving currents in all panel blocks (PB).

[0078] FIG. 8 is a drawing showing panel blocks (PB) of a gamma correction method of a display device according to embodiments of the present invention.

[0079] Since the gamma correction method of the display device according to the embodiments is substantially the same as the gamma correction method of the display device of FIG. 1, except for the determination of the target grayscale voltage, the same reference numbers and reference symbols are used for identical or similar components, and redundant descriptions are omitted.

[0080] Referring to FIGS. 2, FIGS. 3, and FIG. 8, the gamma correction method of the display device of FIG. 8 separately drives an area of ​​the display panel (100) excluding each panel block (PB) of the display panel (100) to measure a first driving current for the area of ​​the display panel (100) excluding each panel block (PB) according to a first grayscale voltage, and calculates a deviation of the first driving current according to the position of each panel block (PB). The target grayscale voltage can be determined differently for each position of the display panel (100) according to the deviation of the first driving current.

[0081] For example, the deviation of the first driving current can be determined based on the first driving current measured by displaying a black gradation (e.g., 0 gradation) on each panel block (PB) and displaying a white gradation (e.g., 255 gradation) on the area of ​​the display panel (100) excluding each panel block (PB). For example, the deviation of the first driving current can be determined based on the first driving current of the central panel block (PB). As another example, the deviation of the first driving current can be determined based on the average value of the first driving currents in all panel blocks (PB).

[0082] FIG. 9 is a flowchart illustrating a gamma correction method for a display device according to embodiments of the present invention.

[0083] Since the gamma correction method of the display device according to the embodiments is substantially the same as the gamma correction method of the display device of FIG. 1, except that the average value of the first driving current is used instead of the first driving current, the same reference numbers and reference symbols are used for identical or similar components, and redundant descriptions are omitted.

[0084] The gamma correction method of the display device of FIG. 9 can measure a first driving current N times (where N is a positive integer greater than or equal to 2) according to a grayscale voltage corresponding to a low grayscale (S310), calculate the average value of the first driving current measured N times (S320), determine a predicted brightness based on a driving current-brightness relationship table and the average value of the first driving current (S330), compare the predicted brightness with a first target brightness for the low grayscale (S340), and if the predicted brightness and the first target brightness are different, determine a first offset value based on the average value of the first driving current and the first target brightness (S350), and correct the first grayscale voltage based on the first offset value (S360). Additionally, the gamma correction method of the display device of FIG. 9 can determine a target grayscale voltage using a driving current-grayscale voltage relationship, the average value of the first driving current, and a target current. Therefore, the gamma correction method of the display device of Fig. 9 can perform gamma correction more accurately than the gamma correction method of the display device of Fig. 1.

[0085] FIG. 10 is a block diagram showing an electronic device according to embodiments of the present invention, and FIG. 11 is a diagram showing an example in which the electronic device of FIG. 10 is implemented as a smartphone.

[0086] Referring to FIGS. 10 and 11, the electronic device (2000) may include a processor (2010), a memory device (2020), a storage device (2030), an input / output device (2040), a power supply (2050), and a display device (2060). In this case, the display device (2060) may be the display device (1000) of FIG. 2. Additionally, the electronic device (2000) may further include several ports capable of communicating with a video card, sound card, memory card, USB device, etc., or communicating with other systems. In one embodiment, as shown in FIG. 11, the electronic device (2000) may be implemented as a smartphone. However, this is exemplary and the electronic device (2000) is not limited thereto. For example, the electronic device (2000) may be implemented as a mobile phone, video phone, smart pad, smart watch, tablet PC, vehicle navigation system, computer monitor, laptop, head-mounted display device, etc.

[0087] The processor (2010) can perform specific calculations or tasks. According to an embodiment, the processor (2010) may be a microprocessor, a central processing unit, an application processor, etc. The processor (2010) may be connected to other components via an address bus, a control bus, a data bus, etc. According to an embodiment, the processor (2010) may also be connected to an expansion bus such as a Peripheral Component Interconnect (PCI) bus.

[0088] The memory device (2020) can store data necessary for the operation of the electronic device (2000). For example, the memory device (2020) may include non-volatile memory devices such as an Erasable Programmable Read-Only Memory (EPROM) device, an Electrically Erasable Programmable Read-Only Memory (EEEPROM) device, a flash memory device, a Phase Change Random Access Memory (PRAM) device, a Resistance Random Access Memory (RRAM) device, a Nano Floating Gate Memory (NFGM) device, a Polymer Random Access Memory (PoRAM) device, a Magnetic Random Access Memory (MRAM) device, a Ferroelectric Random Access Memory (FRAM) device, and / or volatile memory devices such as a Dynamic Random Access Memory (DRAM) device, a Static Random Access Memory (SRAM) device, a mobile DRAM device, etc.

[0089] The storage device (2030) may include a solid state drive (SSD), a hard disk drive (HDD), a CD-ROM, etc.

[0090] The input / output device (2040) may include input means such as a keyboard, keypad, touchpad, touchscreen, mouse, etc., and output means such as a speaker, printer, etc. According to an embodiment, a display device (2060) may be included in the input / output device (2040).

[0091] The power supply (2050) can supply power required for the operation of the electronic device (2000). For example, the power supply (2050) may be a power management integrated circuit (PMIC).

[0092] The display device (2060) can display an image corresponding to the visual information of the electronic device (2000). At this time, the display device (2060) may be an organic light-emitting display device or a quantum dot light-emitting display device, but is not limited thereto. The display device (2060) may be connected to other components through the buses or other communication links. At this time, the gamma correction method of the display device (2060) can perform gamma correction for low grayscale by measuring the driving current. Accordingly, the process time for gamma correction can be shortened compared to when gamma correction for low grayscale is performed by measuring the brightness.

[0093] In one embodiment, the gamma correction method of the display device (2060) measures a first driving current according to a first grayscale voltage corresponding to a low grayscale, determines a predicted brightness based on a driving current-brightness relationship table and the first driving current, compares the predicted brightness with a first target brightness for the low grayscale, and if the predicted brightness and the first target brightness are different, determines a first offset value based on the first driving current and the first target brightness, and corrects the first grayscale voltage based on the first offset value. However, since this has already been explained with reference to FIGS. 1 to 8, a redundant explanation thereof will be omitted.

[0094] In another embodiment, a first driving current corresponding to a grayscale voltage corresponding to a gamma-corrected low grayscale of a display device (2060) is measured N times, the average value of the first driving current measured N times is calculated, a predicted brightness is determined based on a driving current-brightness relationship table and the average value of the first driving current, the predicted brightness is compared with a first target brightness for the low grayscale, and if the predicted brightness and the first target brightness are different, a first offset value is determined based on the average value of the first driving current and the first target brightness, and the first grayscale voltage can be corrected based on the first offset value. However, since this has already been explained with reference to FIG. 9, a redundant explanation thereof will be omitted. Industrial applicability

[0095] The present invention may be applied to display devices and electronic devices including the same. For example, the present invention may be applied to digital TVs, 3D TVs, mobile phones, smartphones, tablet computers, VR devices, PCs, home electronic devices, laptop computers, PDAs, PMPs, digital cameras, music players, portable game consoles, navigation systems, etc.

[0096] Although the invention has been described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims. Explanation of the symbols

[0097] 2000: Electronic devices 2010: Processors 2020: Memory device 2030: Storage device 2040: Input / Output Device 2050: Power Supply Device 2060, 1000: Display device 1100: Display panel driver 100: Display panel 200: Timing controller 300: Gate Driver 400: Source Driver 500: Power voltage supply unit 600: Current measurement unit

Claims

Claim 1 A gamma correction method for a display device comprising: a step of measuring a first driving current according to a first grayscale voltage corresponding to a low grayscale; a step of determining a predicted brightness based on a driving current-brightness relationship table and the first driving current; a step of comparing the predicted brightness with a first target brightness for the low grayscale; a step of determining a first offset value based on the first driving current and the first target brightness when the predicted brightness and the first target brightness are different; and a step of correcting the first grayscale voltage based on the first offset value. Claim 2 A gamma correction method for a display device according to claim 1, further comprising: a step of measuring luminance according to a second grayscale voltage corresponding to a high grayscale; a step of comparing the luminance according to the second grayscale voltage with a second target luminance for the high grayscale; a step of determining a second offset value based on the luminance according to the second grayscale voltage and the second target luminance when the luminance according to the second grayscale voltage and the second target luminance are different; and a step of correcting the second grayscale voltage based on the second offset value. Claim 3 A gamma correction method for a display device according to claim 1, further comprising the step of no longer correcting the first grayscale voltage when the predicted brightness matches the first target brightness. Claim 4 A gamma correction method for a display device according to claim 3, wherein the steps of measuring the first driving current, determining the predicted brightness, comparing, determining the first offset value, and correcting the first grayscale voltage are repeated until the predicted brightness matches the first target brightness. Claim 5 A gamma correction method for a display device according to claim 1, further comprising the step of measuring the luminance according to the first grayscale voltage once, wherein the driving current-luminance relationship table includes the luminance according to the first grayscale voltage. Claim 6 A gamma correction method for a display device according to claim 1, wherein the step of determining the first offset value comprises: determining a target current using the driving current-luminance relationship table and the first target luminance; determining a target grayscale voltage using the driving current-grayscale voltage relationship, the first driving current, and the target current; and determining the first offset value by subtracting the first grayscale voltage from the target grayscale voltage. Claim 7 A gamma correction method for a display device according to claim 6, characterized in that the driving current-grayscale voltage relationship is updated according to the first driving current. Claim 8 A gamma correction method for a display device according to claim 6, further comprising the steps of: driving each panel block of a display panel separately to measure the first driving current for each of the panel blocks according to the first grayscale voltage; and calculating the deviation of the first driving current according to the position of each of the panel blocks, wherein the target grayscale voltage is determined differently for each position of the display panel according to the deviation of the first driving current. Claim 9 A gamma correction method for a display device according to claim 6, further comprising: a step of separately driving an area of ​​the display panel excluding each panel block of the display panel to measure the first driving current for the area of ​​the display panel excluding each panel block according to the first grayscale voltage; and a step of calculating a deviation of the first driving current according to the position of each panel block, wherein the target grayscale voltage is determined differently for each position of the display panel according to the deviation of the first driving current. Claim 10 A gamma correction method for a display device according to claim 1, characterized in that the correction of the first grayscale voltage is performed by adding the first offset value to the first grayscale voltage. Claim 11 A gamma correction method for a display device according to claim 1, characterized in that the first driving current is measured by a current measuring unit connected to a power line to which a power supply voltage is applied, and the power supply voltage is applied to a display panel through the power line. Claim 12 A gamma correction method for a display device comprising: a step of measuring a first driving current N times according to a first grayscale voltage corresponding to a low grayscale; a step of calculating an average value of the first driving current measured N times; a step of determining a predicted brightness based on a driving current-luminance relationship table and the average value of the first driving current; a step of comparing the predicted brightness with a first target brightness for the low grayscale; a step of determining a first offset value based on the average value of the first driving current and the first target brightness when the predicted brightness and the first target brightness are different; and a step of correcting the first grayscale voltage based on the first offset value (N is a positive integer greater than or equal to 2). Claim 13 A gamma correction method for a display device according to claim 12, further comprising: a step of measuring luminance according to a second grayscale voltage corresponding to a high grayscale; a step of comparing the luminance according to the second grayscale voltage with a second target luminance for the high grayscale; a step of determining a second offset value based on the luminance according to the second grayscale voltage and the second target luminance when the luminance according to the second grayscale voltage and the second target luminance are different; and a step of correcting the second grayscale voltage based on the second offset value. Claim 14 A gamma correction method for a display device according to claim 12, further comprising the step of measuring the luminance according to the first grayscale voltage once, wherein the driving current-luminance relationship table includes the luminance according to the first grayscale voltage. Claim 15 A gamma correction method for a display device according to claim 12, wherein the step of determining the first offset value comprises: determining a target current using the driving current-luminance relationship table and the first target luminance; determining a target grayscale voltage using the driving current-grayscale voltage relationship, the average value of the first driving current, and the target current; and determining the first offset value by subtracting the first grayscale voltage from the target grayscale voltage. Claim 16 A gamma correction method for a display device according to claim 15, characterized in that the driving current-grayscale voltage relationship is updated according to the first driving current. Claim 17 A gamma correction method for a display device according to claim 15, further comprising the steps of: driving each panel block of a display panel separately to measure the first driving current for each of the panel blocks according to the first grayscale voltage; and calculating the deviation of the first driving current according to the position of each of the panel blocks, wherein the target grayscale voltage is determined differently for each position of the display panel according to the deviation of the first driving current. Claim 18 A gamma correction method for a display device according to claim 15, further comprising: a step of separately driving an area of ​​the display panel excluding each panel block of the display panel to measure the first driving current for the area of ​​the display panel excluding each panel block according to the first grayscale voltage; and a step of calculating a deviation of the first driving current according to the position of each panel block, wherein the target grayscale voltage is determined differently for each position of the display panel according to the deviation of the first driving current. Claim 19 A gamma correction method for a display device according to claim 12, characterized in that the correction of the first grayscale voltage is performed by adding the first offset value to the first grayscale voltage. Claim 20 A gamma correction method for a display device according to claim 12, characterized in that the first driving current is measured by a current measuring unit connected to a power line to which a power supply voltage is applied, and the power supply voltage is applied to a display panel through the power line.

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