Display device and method for compensating for degradation of display device

Abstract

A display device and a method for compensating for degradation of the display device are provided. The display device includes: a display panel including pixels; a sensing unit configured to measure threshold voltages of the pixels respectively; and a timing controller configured to determine grayscale compensation values ​​corresponding to the threshold voltages with respect to the pixels respectively, and compensate input image data with respect to the pixels respectively based on the grayscale compensation values, wherein the grayscale compensation values ​​have a linear relationship with the grayscale of the input image data by using a linear slope value determined based on the threshold voltage.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2018-0135408 filed in the Korean Intellectual Property Office on November 6, 2018, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] Embodiments of the present disclosure generally relate to a display device and a method of compensating for degradation of the display device. Background Art

[0004] Generally speaking, in an organic light emitting display device including an organic light emitting diode, as time passes, degradation of the organic light emitting diode or the driving transistor (hereinafter referred to as "degradation of a pixel") occurs corresponding to the driving time and the driving current amount. When a pixel degrades, the brightness of the pixel decreases. Therefore, the display quality may be reduced, or an afterimage may appear on the screen.

[0005] The threshold voltage (Vth) of the driving transistor provided in the pixel is different depending on the location of the pixel. The change in threshold voltage is caused by process errors in the process of forming the thin film transistor. Although the same driving voltage is applied to the driving transistor of each pixel, it still causes a difference between the currents flowing through the organic light emitting diode. Therefore, the pixels emit light with different brightness.

[0006] Specifically, when a pixel displays a white image for a long time, the threshold voltage of the driving transistor moves in a negative direction due to a negative bias temperature illumination stress (NTBis) applied to the driving transistor, etc. The data voltage can be compensated from the outside corresponding to the movement of the threshold voltage. However, the range of compensation is limited, and therefore, there is a limitation in compensating the threshold voltage. Specifically, when the threshold voltage exceeds the range of compensation due to the continuous movement of the threshold voltage in the negative direction, the brightness increases, and therefore, the reliability of the display device decreases. Summary of the invention

[0007] Embodiments disclosed herein provide a display device capable of accurately compensating for degradation of a pixel by considering a position where the pixel is located, and a method of compensating for degradation of the display device.

[0008] Embodiments also provide a display device capable of stably compensating for degradation of a pixel even when a threshold voltage moves in a negative direction, and a method of compensating for degradation of the display device.

[0009] According to aspects of the present disclosure, a display device is provided, comprising: a display panel including pixels; a sensing unit configured to measure threshold voltages of the pixels respectively; and a timing controller configured to respectively determine grayscale compensation values ​​corresponding to the threshold voltages relative to the pixels, and respectively compensate input image data relative to the pixels based on the grayscale compensation values, wherein the grayscale compensation values ​​have a linear relationship with the grayscale of the input image data by using a linear slope value determined based on the threshold voltage.

[0010] The timing controller may be configured to calculate threshold voltage mobilities of pixels based on minimum threshold voltages among the threshold voltages, calculate grayscale compensation levels of pixels according to the threshold voltage mobilities, and generate linear slope values ​​and grayscale compensation values ​​based on the grayscale compensation levels.

[0011] The threshold voltage mobility can be calculated using Equation 1 below.

[0012] Equation 1

[0013] ΔVth=Vth-Vth(target)

[0014] Here, ΔVth is the threshold voltage mobility, Vth is the measured threshold voltage, and Vth(target) is the minimum threshold voltage.

[0015] The grayscale compensation level can be calculated using Equation 2 below.

[0016] Equation 2

[0017]

[0018] Here, ΔGray is the grayscale compensation level, ΔVth is the threshold voltage mobility, bit is the number of bits of the input image data, Vdata(max gray) is the data voltage corresponding to the maximum grayscale of the input image data, and Vdata(mingray) is the data voltage corresponding to the minimum grayscale of the input image data.

[0019] The linear slope value may be set relative to each of the pixels and may be calculated using the following Equation 3.

[0020] Equation 3

[0021]

[0022] Here, α is a linear slope value, and ΔGray is a gray compensation level of each of the pixels.

[0023] The linear slope value may be set equally with respect to the pixel and may be calculated using the following Equation 4.

[0024] Equation 4

[0025]

[0026] Here, α is a linear slope value, and ΔGray is a gray compensation level of a pixel having a maximum threshold voltage among the threshold voltages.

[0027] The grayscale compensation value can be calculated using the following equation 5.

[0028] Equation 5

[0029] GRAY'=α×GRAY+ΔGray

[0030] Here, GRAY' is a grayscale compensation value, GRAY is the grayscale of the input image data, ΔGray is a grayscale compensation level, and α is a linear slope value.

[0031] The timing controller may be configured to store the linear slope value and the grayscale compensation level relative to each of the pixels in a lookup table, and when any input image data supplied externally is received, the timing controller may be configured to load the linear slope value and the grayscale compensation level corresponding to the pixel in which the arbitrary input image data is to be displayed from the lookup table, and the timing controller may be configured to determine the grayscale compensation value relative to the grayscale of the arbitrary input image data based on the linear slope value and the grayscale compensation level.

[0032] According to another aspect of the present disclosure, a method for compensating for degradation of a display device is provided, the method comprising measuring a threshold voltage of a pixel, respectively determining a grayscale compensation value corresponding to the threshold voltage relative to the pixel, and compensating input image data corresponding to the pixel based on the grayscale compensation value, the grayscale compensation value being defined as having a linear relationship with the grayscale of the input image data according to a linear slope value determined based on the threshold voltage.

[0033] Determining the gray compensation value may include respectively calculating threshold voltage mobilities of pixels based on minimum threshold voltages among the threshold voltages, respectively calculating gray compensation levels of pixels according to the threshold voltage mobilities, and generating a linear slope value and a gray compensation value based on the gray compensation levels.

[0034] The threshold voltage mobility can be calculated using Equation 6 below.

[0035] Equation 6

[0036] ΔVth=Vth-Vth(target)

[0037] Here, ΔVth is the threshold voltage mobility, Vth is the measured threshold voltage, and Vth(target) is the minimum threshold voltage.

[0038] The grayscale compensation level can be calculated using Equation 7 below.

[0039] Equation 7

[0040]

[0041] Here, ΔGray is the grayscale compensation level, ΔVth is the threshold voltage mobility, bit is the number of bits of the input image data, Vdata(max gray) is the data voltage corresponding to the maximum grayscale of the input image data, and Vdata(mingray) is the data voltage corresponding to the minimum grayscale of the input image data.

[0042] A linear slope value may be set with respect to each of the pixels and may be calculated using the following Equation 8.

[0043] Equation 8

[0044]

[0045] Here, α is a linear slope value, and ΔGray is a gray compensation level of each of the pixels.

[0046] The linear slope value may be set equally with respect to the pixel and may be calculated using the following Equation 9.

[0047] Equation 9

[0048]

[0049] Here, α is a linear slope value, and ΔGray is a gray compensation level of a pixel having a maximum threshold voltage among the threshold voltages.

[0050] The grayscale compensation value can be calculated using the following equation 10.

[0051] Equation 10

[0052] GRAY'=α×GRAY+ΔGray

[0053] Here, GRAY' is a grayscale compensation value, GRAY is the grayscale of the input image data, ΔGray is a grayscale compensation level, and α is a linear slope value.

[0054] The linear slope value and the grayscale compensation level with respect to each of the pixels may be stored in a lookup table.

[0055] Compensating input image data may include: when receiving arbitrary input image data from the outside, loading a linear slope value and a grayscale compensation level corresponding to a pixel in which the arbitrary input image data will be displayed from a lookup table, determining a grayscale compensation value relative to the grayscale of the input image data based on the loaded linear slope value and the loaded grayscale compensation level, and outputting compensated image data corresponding to the determined grayscale compensation value. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 A diagram illustrating a display device according to an embodiment of the present disclosure.

[0057] Figure 2 To show Figure 1 An example of a pixel is shown in FIG.

[0058] Figure 3 FIG. 4 is a flowchart illustrating a method of compensating for degradation of a display device according to an embodiment of the present disclosure.

[0059] Figure 4 is a diagram showing the shift of the threshold voltage of a pixel.

[0060] Figure 5 FIG. 1 is a diagram illustrating a method of compensating for degradation of a display device according to a first embodiment of the present disclosure.

[0061] Figure 6 FIG. 2 is a diagram illustrating a method of compensating for degradation of a display device according to a second embodiment of the present disclosure. DETAILED DESCRIPTION

[0062] By referring to the detailed description and drawings of the embodiments, the features of the inventive concept and its implementation method can be more easily understood. Hereinafter, the embodiments will be described in more detail with reference to the drawings. However, the described embodiments can be embodied in various different forms and should not be interpreted as being limited to the embodiments shown herein. On the contrary, these embodiments are provided as examples so that the disclosure will be thorough and complete, and the aspects and features of the inventive concept will be fully conveyed to those skilled in the art. Therefore, it may not be described that the processes, elements and techniques that are unnecessary for those of ordinary skill in the art to fully understand the aspects and features of the inventive concept. Unless otherwise stated, throughout the drawings and written descriptions, the same reference numerals represent the same elements, and therefore, their descriptions are not repeated. In addition, parts that are not related to the description of the embodiments may not be shown to make the description clear. In the drawings, for clarity, the relative sizes of elements, layers and regions may be magnified.

[0063] Various embodiments are described herein with reference to cross-sectional views, which are schematic diagrams of embodiments and / or intermediate structures. As such, variations from the illustrated shapes due to, for example, manufacturing techniques and / or deviations can be expected. In addition, the specific structural or functional descriptions disclosed herein are merely illustrative, for the purpose of describing embodiments according to the concepts of the present disclosure. Furthermore, as will be appreciated by those skilled in the art, the described embodiments may be modified in a variety of different ways, all without departing from the spirit or scope of the present disclosure.

[0064] In the detailed description, for the purpose of explanation, many specific details are set forth to provide a thorough understanding of various embodiments. However, it is apparent that various embodiments can be practiced without these specific details or with one or more equivalent arrangements. In other instances, well-known structures and devices are shown in block diagram form to avoid unnecessary obfuscation of various embodiments.

[0065] It should be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the spirit and scope of the present disclosure, the first element, component, region, layer or part described below may be referred to as a second element, component, region, layer or part.

[0066] It should be understood that when an element, layer, region or component is referred to as being "on", "connected to" or "coupled to" another element, layer, region or component, it may be directly on, directly connected to or directly coupled to another element, layer, region or component, or one or more intermediate elements, layers, regions or components may be present. However, "direct connection / direct coupling" refers to a component being directly connected or coupled to another component without intermediate components. At the same time, other expressions describing the relationship between components, such as "between", "immediately between" or "adjacent to" and "directly adjacent to", may be similarly interpreted. In addition, it should also be understood that when an element or layer is referred to as being "between" two elements or layers, it may be the only element or layer between the two elements or layers, or one or more intermediate elements or layers may also be present.

[0067] The terms used herein are only used to describe specific embodiments and are not intended to limit the present disclosure. As used herein, the singular form "a" is intended to also include the plural form, unless the context clearly states otherwise. It will be further understood that when used in this specification, the terms "include", "comprise" and "have" indicate the presence of stated features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or their groups. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0068] When a specific embodiment can be implemented in different ways, the specific processing order can be performed differently from the described order. For example, two processes described in succession can be performed substantially at the same time, or in the reverse order of the described order.

[0069] The electrical or electronic device and / or any other related device or component according to the embodiments of the present disclosure described herein can be implemented using any suitable hardware, firmware (e.g., application specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, the various components of these devices can be formed on an integrated circuit (IC) chip or on a separate IC chip. In addition, the various components of these devices can be implemented on a flexible printed circuit film, a tape carrier package (TCP), a printed circuit board (PCB), or formed on a substrate. In addition, the various components of these devices can be processes or threads running on one or more processors, wherein the processor is located in one or more computing devices for executing computer program instructions and interacting with other system components to perform the various functions described herein. The computer program instructions are stored in a memory that can be implemented in a computing device using a standard storage device, such as a random access memory (RAM). The computer program instructions can also be stored in other non-temporary computer-readable media, such as a CD-ROM, a flash drive, etc. In addition, it should be appreciated by those skilled in the art that the functions of each computing device can be combined or integrated into a single computing device, or the functions of a specific computing device can be distributed between one or more other computing devices without departing from the spirit and scope of the embodiments of the present disclosure.

[0070] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meanings as commonly understood by those of ordinary skill in the art to which the inventive concept belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and / or in this specification, and should not be interpreted in an idealized or overly formal sense, unless explicitly defined as such in this article.

[0071] Figure 1 A diagram illustrating a display device according to an embodiment of the present disclosure.

[0072] refer to Figure 1 , the display device 100 according to an embodiment of the present disclosure may include a display panel 110, a scan driver 120, a data driver 130, an emission driver 140, a sensing unit 150, a timing controller 160, and a memory 170. The display device 100 may be a device that outputs an image based on externally supplied image data (e.g., first image data DATA1) provided from the outside. For example, the display device 100 may be an organic light emitting display device.

[0073] The display panel 110 may include a plurality of first scan lines S11 to S1n, a plurality of second scan lines S21 to S2n, a plurality of data lines D1 to Dm, a plurality of emission control lines E1 to En, a plurality of feedback lines F1 to Fm, and a plurality of pixels 111 (n and m are integers of 2 or more). The pixels 111 may be arranged at intersections of the first scan lines S11 to S1n, the second scan lines S21 to S2n, the data lines D1 to Dm, the emission control lines E1 to En, and the feedback lines F1 to Fm.

[0074] Each of the pixels 111 may store a data signal in response to the first scan signal and the second scan signal, and may emit light based on the stored data signal. Figure 2 The configuration of the pixel 111 is described in detail.

[0075] The scan driver 120 may generate a first scan signal and a second scan signal based on the scan drive control signal SCS. That is, the scan driver 120 may supply the first scan signal to the pixel 111 through the first scan lines S11 to S1n during a display period in one frame, and may supply the second scan signal to the pixel 111 through the second scan lines S21 to S2n during a sensing period for sensing the characteristics of the pixel 111. The scan drive control signal SCS may be provided to the scan driver 120 from the timing controller 160. The scan drive control signal SCS may include a start pulse signal and a clock signal, and the scan driver 120 may include a shift register that sequentially generates the scan signals corresponding to the start pulse signal and the clock signal.

[0076] The data driver 130 may generate a data signal based on the data drive control signal DCS and image data (e.g., the second image data DATA2). The data driver 130 may provide the display panel 110 with the data signal generated based on the data drive control signal DCS during the display period. That is, the data driver 130 may supply the data signal to the pixel 111 through the data lines D1 to Dm. The data drive control signal DCS may be provided to the data driver 130 from the timing controller 160.

[0077] The sensing unit 150 may be coupled to the feedback lines F1 to Fm, and may measure (or sense) characteristics of the pixel 111 based on the control signal CS. The characteristics of the pixel 111 are characteristics of a driving transistor provided in each pixel 111, and may include a threshold voltage Vth and / or mobility information of the driving transistor, etc. The sensing unit 150 may transmit information related to the measured characteristics of the pixel 111 to the timing controller 160.

[0078] In some embodiments, the data driver 130 may apply a sensing voltage to a specific data line (e.g., the mth data line Dm) in response to a control signal CS during a sensing period, and the sensing unit 150 may measure characteristics of a driving transistor provided in one or more pixels 111 based on a current or voltage fed back through a corresponding feedback line (e.g., the mth feedback line Fm) in response to the sensing voltage.

[0079] The emission driver 140 may generate an emission control signal based on the emission driving control signal ECS. The emission driving control signal ECS may be provided to the emission driver 140 from the timing controller 160. The emission driver 140 may generate the emission control signal based on the emission driving control signal ECS and the clock signal simultaneously or sequentially.

[0080] The timing controller 160 may control operations of the scan driver 120, the data driver 130, the emission driver 140, and the sensing unit 150. The timing controller 160 may generate a scan driving control signal SCS, a data driving control signal DCS, an emission driving control signal ECS, and a control signal CS, and may control each of the scan driver 120, the data driver 130, the emission driver 140, and the sensing unit 150 based on the generated signals.

[0081] In various embodiments of the present disclosure, the timing controller 160 may calculate a threshold voltage mobility of each pixel 111 based on characteristics of the pixel 111 , and may correct input image data (eg, first image data DATA1 ) based on the threshold voltage mobility.

[0082] For example, the timing controller 160 may calculate the threshold voltage mobility by comparing the threshold voltage Vth of the pixel 111 measured during the sensing period with the target threshold voltage. The target threshold voltage may be the minimum threshold voltage Vth(min) among the threshold voltages Vth measured with respect to the pixel 111.

[0083] The timing controller 160 may determine the grayscale compensation level according to the calculated threshold voltage mobility, and may calculate the grayscale compensation value corresponding to the grayscale compensation level. In an embodiment, the grayscale compensation value may be calculated using a linear equation. The linear equation may include a correlation between the grayscale of the input image data and the grayscale compensation value. The timing controller 160 may store information related to the grayscale compensation value defined by the linear equation in the form of a lookup table or the like.

[0084] The timing controller 160 can obtain a grayscale compensation value corresponding to the grayscale of the input image data (e.g., the first image data DATA1) by using the stored lookup table as described above, and can generate corrected image data (e.g., the second image data DATA2) by reflecting the obtained grayscale compensation value, and can then provide the corrected image data to the data driver 130.

[0085] The memory 170 may store a lookup table having grayscale compensation values ​​generated by the timing controller 160 as described above.

[0086] In various embodiments, the display device 100 may further include a power supply unit. The power supply unit may generate a driving voltage suitable for driving the display device 100. The driving voltage may include a first driving voltage ELVDD and a second driving voltage ELVSS. The first driving voltage ELVDD may be greater than the second driving voltage ELVSS.

[0087] At the same time, despite Figure 1 The display panel 110 is shown to include feedback lines F1 to Fm, and the data driver 130 is coupled to the feedback lines F1 to Fm, but the display panel 110 is not limited thereto. For example, the display panel 110 of other embodiments does not include the feedback lines F1 to Fm, and the data lines D1 to Dm may be used as the feedback lines F1 to Fm by time division driving.

[0088] Figure 2 To show Figure 1 An example of a pixel is shown in FIG.

[0089] refer to Figure 2 , the pixel 111 may include first to third transistors T1 to T3, a storage capacitor Cst, and an organic light emitting diode OLED. The pixel 111 may be coupled to the data driver 130 through the data line Dj, and may be coupled to the sensing unit 150 through the feedback line Fj. In addition, the pixel 111 may be coupled to the scan driver 120 through the first scan line S1i and the second scan line S2i.

[0090] An anode electrode of the organic light emitting diode OLED may be coupled to the second electrode of the first transistor T1 (e.g., coupled to the second node N2), and a cathode electrode of the organic light emitting diode OLED may be coupled to the second driving voltage ELVSS. The organic light emitting diode OLED generates light (e.g., with a predetermined brightness) corresponding to the amount of current supplied from the first transistor T1.

[0091] A first electrode of the first transistor (driving transistor) T1 may be coupled to a first driving voltage ELVDD, and a second electrode of the first transistor T1 may be coupled to an anode electrode / second node N2 of the organic light emitting diode OLED. A gate electrode of the first transistor T1 may be coupled to the first node N1. The first transistor T1 controls the amount of current flowing through the organic light emitting diode OLED corresponding to the voltage of the first node N1.

[0092] A first electrode of the second transistor T2 may be coupled to the data line Dj, and a second electrode of the second transistor T2 may be coupled to the first node N1. A gate electrode of the second transistor T2 may be coupled to the first scan line S1i. When a first scan signal is supplied to the first scan line S1i, the second transistor T2 may be turned on to transmit a voltage from the data line Dj to the first node N1.

[0093] In various embodiments of the present disclosure, the data signal may be supplied to the data line Dj in synchronization with the first scan signal supplied during the display period, and the sensing voltage may be supplied to the data line Dj in synchronization with the first scan signal supplied during the sensing period.

[0094] The third transistor T3 may be coupled between the feedback line Fj and the second electrode / second node N2 of the first transistor T1. The gate electrode of the third transistor T3 may be coupled to the second scan line S2i. When the second scan signal is supplied to the second scan line S2i, the third transistor T3 may be turned on to electrically couple the feedback line Fj and the second node N2 to each other.

[0095] In various embodiments of the present disclosure, a reference voltage may be supplied to the feedback line Fj in synchronization with the second scan signal supplied during the display period, and any current or voltage may be supplied to the feedback line Fj from the second node N2 in synchronization with the second scan signal supplied during the sensing period. The current or voltage supplied to the feedback line Fj during the sensing period may be transmitted to the sensing unit 150 and may be used to measure characteristics of the pixel 111. The characteristics of the pixel 111 may include a threshold voltage Vth and / or mobility information of the first transistor T1.

[0096] The storage capacitor Cst may be coupled between the first node N1 and the second node N2. The storage capacitor Cst may store a voltage corresponding to a difference in voltage between the first node N1 and the second node N2.

[0097] In various embodiments of the present disclosure, the brightness of the pixel 111 is mainly determined by the data signal. However, the characteristic value of the first transistor T1 may be additionally reflected to the brightness of the pixel 111. That is, in the present disclosure, an external compensation method may be applied, in which the characteristic of the first transistor T1 is sensed during the sensing period, and the first image data DATA1 is changed by reflecting information related to the sensed characteristic. In this embodiment, an image with uniform image quality may be displayed in the display panel 110 regardless of the characteristic change of the first transistor T1.

[0098] In various embodiments of the present disclosure, a sensing period in which the characteristics of the pixel 111 are measured may be performed at least once before the display device 100 is released into the market (e.g., during a manufacturing stage). Initial characteristic information of the first transistor T1 may be stored before the display device 100 is released into the market, and the first image data DATA1 may be corrected (e.g., second image data DATA2 is generated) using the initial characteristic information so that an image with uniform image quality may be displayed in the display panel 110.

[0099] Alternatively, in various embodiments of the present disclosure, the sensing period in which the characteristics of the pixel 111 are measured may be performed even after the display device 100 is actually used. For example, the sensing period may be located at a portion of the time when the display device 100 is turned on and / or the time when the display device 100 is turned off. In addition, the sensing period may be located at a portion of the vertical blank period that occurs between each display period. Thus, even when the display device 100 is being driven, the characteristic information (e.g., the characteristics of the driving transistor / first transistor T1 included in each of the pixels 111) may be updated in real time to be reflected in the data signal generation. Therefore, the display panel 110 can continuously display an image with uniform image quality.

[0100] Figure 3 FIG. 4 is a flowchart illustrating a method of compensating for degradation of a display device according to an embodiment of the present disclosure. Figure 4 is a diagram showing the shift of the threshold voltage of a pixel. Figure 5 FIG. 1 is a diagram illustrating a method of compensating for degradation of a display device according to a first embodiment of the present disclosure. Figure 6 FIG. 2 is a diagram illustrating a method of compensating for degradation of a display device according to a second embodiment of the present disclosure.

[0101] refer to Figure 3 , the display device 100 according to the embodiment of the present disclosure performs threshold voltage sensing on the pixel 111 ( 301 ).

[0102] When the driving time elapses, the data driver 130 may measure the threshold voltage Vth of the driving transistor provided in the pixel 111, and may transmit the measured threshold voltage Vth to the timing controller 160. The measurement of the threshold voltage Vth may be performed for each of the pixels 111 selected in the above-mentioned sensing period. Figure 4 Compared with the initial threshold voltage shown in , the threshold voltage Vth measured with respect to each of the pixels 111 may have a value moving within the range of a minimum threshold voltage Vth(min) to a maximum threshold voltage Vth(max).

[0103] Next, the display device 100 determines the threshold voltage mobility with respect to each of the pixels 111 by comparing the threshold voltage Vth measured with respect to the pixels 111 with the target threshold voltage (302). In various embodiments of the present disclosure, the target threshold voltage may be the minimum threshold voltage Vth(min) among the threshold voltages Vth measured with respect to the pixels 111.

[0104] In an embodiment of the present disclosure, the timing controller 160 may calculate the threshold voltage mobility using the following Equation 1 based on the threshold voltage measured with respect to each of the pixels 111 .

[0105] Equation 1

[0106] ΔVth=Vth-Vth(target)

[0107] Here, ΔVth is the threshold voltage mobility, Vth is the measured threshold voltage, and Vth(target) is the target threshold voltage.

[0108] Next, the display device 100 calculates the grayscale compensation level of each of the pixels 111 according to the threshold voltage mobility (303). For example, the timing controller 160 may allocate data voltages corresponding to the grayscales constituting the input image data, respectively. In addition, the timing controller 160 may calculate the grayscale compensation level according to the threshold voltage mobility by using the allocated data voltages corresponding to the maximum grayscale and the minimum grayscale of the input image data, respectively, and the number of bits of the input image data. In an embodiment, the grayscale compensation level may be calculated using the following equation 2.

[0109] Equation 2

[0110]

[0111] Here, ΔGray is the grayscale compensation level, ΔVth is the threshold voltage mobility, (2 bit)bit is the number of bits of the input image data, Vdata(max gray) is the data voltage corresponding to the maximum grayscale, and Vdata(min gray) is the data voltage corresponding to the minimum grayscale. In the example of the present embodiment, the maximum grayscale is the grayscale corresponding to white, which is grayscale 255, and the minimum grayscale is the grayscale corresponding to black, which is grayscale 0.

[0112] Next, the display device 100 determines a grayscale compensation value for each of the pixels 111 according to the grayscale compensation level (304). In an embodiment, the grayscale compensation value refers to a compensated grayscale relative to the grayscale of the input image data, and may be defined as a linear equation including a correlation between the grayscale of the input image data and the compensated grayscale. In an embodiment, the linear equation may be defined using the following equation 3.

[0113] Equation 3

[0114] GRAY'=α×GRAY+ΔGray

[0115] Here, GRAY' is a grayscale compensation value, GRAY is the grayscale of the input image data, and ΔGray is a grayscale compensation level. In addition, α is a value defined using the following equation 4.

[0116] Equation 4

[0117]

[0118] In the first embodiment of the present disclosure, α may be set with respect to each of the pixels 111. That is, in the first embodiment of the present disclosure, α may have different values, which may correspond to the grayscale compensation level of each of the pixels 111. Figure 5 Graph 2 shows the linear relationship between the grayscale of the input image data and the grayscale compensation value defined in this embodiment. Figure 5 The first straight line L1 of represents the linear relationship of a pixel having a threshold voltage mobility of 0 (eg, a pixel having a minimum threshold voltage Vth(min)), and Figure 5 The second straight line L2 represents the linear relationship of the pixel with the largest threshold voltage mobility (eg, the pixel with the maximum threshold voltage Vth(max)). Figure 5 As shown in , the straight lines representing the relationship between the grayscale of input image data and the grayscale compensation value (which corresponds to the threshold voltage mobility) may have different slopes (α).

[0119] Meanwhile, in the second embodiment of the present disclosure, α may be set based on the pixel having the maximum threshold voltage Vth(max). That is, in the second embodiment of the present disclosure, α may be determined corresponding to the grayscale compensation level of the pixel having the maximum threshold voltage Vth(max), and may be determined to be the same value with respect to all pixels 111. Figure 6 Graph 2 shows the linear relationship between the grayscale of the input image data and the grayscale compensation value defined in this embodiment. Figure 6 The first straight line L1′ represents the linear relationship of a pixel having a threshold voltage mobility of 0 (eg, a pixel having a minimum threshold voltage Vth(min)), and Figure 6 The second straight line L2' represents the linear relationship of the pixel with the largest threshold voltage mobility (eg, the pixel with the maximum threshold voltage Vth(max)). Figure 6 As shown in , the straight line representing the relationship between the grayscale of input image data and the grayscale compensation value has the same slope (α) regardless of the threshold voltage mobility.

[0120] Meanwhile, in the present disclosure, Figure 5 and Figure 6 As shown in , even when a shift in the threshold voltage in the negative direction occurs in an arbitrary pixel, grayscales can be stably compensated without limiting the compensation range with respect to all grayscales.

[0121] The display device 100 stores information about the gray compensation value determined with respect to each of the pixels 111 (305). For example, the timing controller 160 may store the gray compensation level and the value α determined with respect to each of the pixels 111 in the memory 170 in the form of a lookup table.

[0122] The display device 100 may perform image data correction (306). For example, the display device 100 may correct input image data (e.g., first image data DATA1) received from the outside by using information related to the stored grayscale compensation value, and may generate corrected image data (e.g., second image data DATA2), and then may supply the corrected image data to the data driver 130.

[0123] To this end, the display device 100 may determine the grayscale of the input image data. The display device 100 may load the grayscale compensation level and the value α stored in the memory 170 with respect to the pixel 111 in which the input image data will be displayed. The display device 100 may calculate the grayscale compensation value using the above equation 3 based on the determined grayscale of the input image data, the loaded grayscale compensation level, and the loaded value α. The display device 100 may generate corrected image data corresponding to the grayscale compensation value.

[0124] In the display device and method according to the present disclosure, brightness non-uniformity due to threshold voltage variation between pixels may be reduced or minimized.

[0125] Furthermore, in the display device and method according to the present disclosure, degradation may be compensated with respect to a pixel in which a shift in the threshold voltage in the negative direction occurs.

[0126] Exemplary embodiments have been disclosed herein, and although specific terms are used, they are used and interpreted in a general and descriptive sense only and not for purposes of limitation. In some cases, as will be apparent to one of ordinary skill in the art to which this application is submitted, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments, unless expressly indicated otherwise. Accordingly, various changes in form and detail may be made without departing from the spirit and scope of the present disclosure as set forth in the appended claims (functional equivalents of which are included herein).

Claims

1. A display device, comprising: Display panel, including pixels; A sensing unit configured to measure the threshold voltage of each pixel; as well as a timing controller configured to respectively determine grayscale compensation values ​​of compensated grayscales corresponding to the threshold voltages of the pixels and corresponding to grayscales of input image data input from the outside, and to respectively compensate the input image data of the pixels based on the grayscale compensation values, wherein the grayscale compensation value is determined according to a linear equation that gradually increases as the grayscale of the input image data increases, The slope of the linear equation is determined according to the threshold voltage of the driving transistor included in the pixel, wherein the timing controller is configured to: calculate the threshold voltage mobility of the pixels based on the minimum threshold voltage among the threshold voltages, calculate the grayscale compensation level of the pixels based on the threshold voltage mobility, and generate the slope of the linear equation and the grayscale compensation value based on the grayscale compensation level, Wherein the linear equation is the following equation: GRAY'=α×GRAY+ΔGray Wherein GRAY' is the grayscale compensation value, GRAY is the grayscale of the input image data, ΔGray is the grayscale compensation level, and α is the slope of the linear equation.

2. The display device according to claim 1, wherein the threshold voltage mobility is calculated using the following equation 1: Equation 1 AVth=Vth-Vth(target) Wherein ΔVth is the threshold voltage mobility, Vth is the measured threshold voltage, and Vth(target) is the minimum threshold voltage.

3. The display device of claim 2, wherein the grayscale compensation levels are calculated using the following equation 2: Equation 2 Wherein bit is the number of bits of the input image data, Vdata(max gray) is the data voltage corresponding to the maximum grayscale of the input image data, and Vdata(min gray) is the data voltage corresponding to the minimum grayscale of the input image data.

4. The display device of claim 3 , wherein the slope of the linear equation is set with respect to each of the pixels and is calculated using the following equation 3: Equation 3 Wherein ΔGray is the grayscale compensation level of each of the pixels.

5. The display device of claim 3, wherein the slope of the linear equation is set equally with respect to the pixel and is calculated using Equation 4: Equation 4 Wherein ΔGray is the gray compensation level of the pixel having the maximum threshold voltage among the threshold voltages.

6. A display device as described in claim 1, wherein the timing controller is configured to store the slope of the linear equation and the grayscale compensation level relative to each of the pixels in a lookup table, and when any input image data supplied externally is received, the timing controller is configured to load the slope of the linear equation and the grayscale compensation level corresponding to the pixel in which the arbitrary input image data is to be displayed from the lookup table, and the timing controller is configured to determine the grayscale compensation value relative to the grayscale of the arbitrary input image data based on the slope of the linear equation and the grayscale compensation level.

7. A method for compensating for degradation of a display device, the method comprising: measuring the threshold voltage of each pixel; respectively determining grayscale compensation values ​​of compensated grayscales corresponding to the threshold voltages of the pixels and corresponding to grayscales of input image data input from the outside; as well as compensating the input image data corresponding to the pixel based on the grayscale compensation value, wherein the grayscale compensation value is determined according to a linear equation that gradually increases as the grayscale of the input image data increases, The slope of the linear equation is determined according to the threshold voltage of the driving transistor included in the pixel, Wherein determining the grayscale compensation value comprises: respectively calculating the threshold voltage mobility of the pixels based on a minimum threshold voltage among the threshold voltages; calculating the grayscale compensation level of the pixels respectively according to the threshold voltage mobility; and generating the slope of the linear equation and the gray compensation value based on the gray compensation level, Wherein the linear equation is the following equation: GRAY'=α×GRAY+ΔGray Wherein GRAY' is the grayscale compensation value, GRAY is the grayscale of the input image data, ΔGray is the grayscale compensation level, and α is the slope of the linear equation.

8. The method of claim 7, wherein the threshold voltage mobility is calculated using the following equation 6: Equation 6 AVth=Vth-Vth(target) Wherein ΔVth is the threshold voltage mobility, Vth is the measured threshold voltage, and Vth(target) is the minimum threshold voltage.

9. The method of claim 8, wherein the grayscale compensation level is calculated using the following equation 7: Equation 7 Wherein bit is the number of bits of the input image data, Vdata(max gray) is the data voltage corresponding to the maximum grayscale of the input image data, and Vdata(min gray) is the data voltage corresponding to the minimum grayscale of the input image data.

10. The method of claim 9, wherein the slope of the linear equation is generated with respect to each of the pixels using the following Equation 8: Equation 8 Wherein ΔGray is the grayscale compensation level of each of the pixels.

11. The method of claim 9, wherein the slope of the linear equation is set equally with respect to the pixel and is generated using the following equation 9: Equation 9 Wherein ΔGray is the gray compensation level of the pixel having the maximum threshold voltage among the threshold voltages.

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