Display device

Abstract

The utility model provides a display device. Each of the pixels of the display device includes stages connected to each other in series. Each of the stages includes a light emitting element. The storage unit stores position information of a defective pixel among the pixels in a case where there is a defect in the stage. The compensation unit generates compensation data by compensating the gradation value in the image data of the normal pixel on the basis of the first degradation coefficient and compensating the gradation value of the defective pixel corresponding to the position information on the basis of a second degradation coefficient different from the first degradation coefficient. The data driving section generates a data voltage based on the compensated data and supplies the data voltage to the pixels.

Description

Technical Field

[0001] The utility model relates to a display device. Background Art

[0002] With increasing interest in information display and increasing demand for the use of portable information media, demand for and commercialization of display devices are being intensively pursued. Utility Model Content

[0003] When a display device is driven for a long time, the light-emitting element may degrade, and the brightness of the display device may decrease or the display quality may decrease for the same image data. The display device can compensate for the decrease in brightness or display quality of the display device by accumulating the driving time and compensating the image data based on the accumulated driving time.

[0004] The purpose of the present invention is to provide a display device with improved display quality and a driving method of the display device.

[0005] According to an embodiment of the present invention, a display device includes: a display panel including pixels, each of the pixels including stages connected in series with each other, each of the stages including a light-emitting element; a storage unit storing position information of a defective pixel among the pixels when a defect exists in the stage; a compensation unit compensating for the grayscale value within image data of a normal pixel among the pixels based on a first degradation coefficient, and compensating for the grayscale value of the defective pixel corresponding to the position information based on a second degradation coefficient different from the first degradation coefficient, thereby generating compensated data; and a data driving unit generating a data voltage based on the compensated data, and providing the data voltage to the pixel.

[0006] The pixels of the display panel are connected to a data line, a first scan line, a second scan line, and a sensing line, and the data driving unit may be configured to sense light emission characteristics of the pixels through the sensing lines during a sensing period.

[0007] The display device may further include: a timing control unit, which receives a control signal and an image signal from the outside, and provides the compensation unit with image data for rearranging the image signal into image data that matches the arrangement of the pixels; and a scan drive unit, which is equipped with the display panel and supplies a first scan signal and a second scan signal to the first scan line and the second scan line, respectively, wherein the timing control unit is configured to generate a data control signal and a scan control signal corresponding to the received control signal, and provide the data control signal to the data drive unit, and provide the scan control signal to the scan drive unit.

[0008] Each of the pixels may further include the same pixel circuit for providing a drive current to the stages, the pixels may include the same number of stages as one another, and the light emitting elements of the pixels may have the same size as one another and emit light in the same color.

[0009] One of the stages of the defective pixel may include a short-circuit defect portion or a portion where the short-circuit defect is repaired, at least a portion of the light-emitting elements in the one stage may not emit light, and the light-emitting elements in the remaining stages may emit light.

[0010] Each of the pixels may include two of the levels, and the storage part may not include position information of the normal pixels and information on the number of defective levels.

[0011] Each of the pixels may include more than three of the levels, the defective pixels may include a first defective pixel and a second defective pixel, the first defective pixel includes one defective level having the defect, and the second defective pixel includes two defective levels having the defect, the storage unit stores position information and quantity information of the defective levels of each of the first defective pixel and the second defective pixel, and the compensation unit may compensate for the grayscale value of the first defective pixel based on the second degradation coefficient, and compensate for the grayscale value of the second defective pixel based on a third degradation coefficient different from the first degradation coefficient and the second degradation coefficient.

[0012] The compensation unit may include: an accumulation circuit that calculates a driving time by accumulating grayscale values ​​within the compensated data; a memory device that stores the driving time; and a compensation circuit that calculates a compensation value for each of the pixels based on the driving time and the first degradation coefficient and the second degradation coefficient, and uses the compensation value to compensate for the grayscale values ​​within the image data.

[0013] Each of the pixels may include: a first transistor electrically connected between a first power line and a second power line; a second transistor electrically connected between the data line and a gate electrode of the first transistor; a third transistor electrically connected between an electrode of the first transistor and the sensing line; and a storage capacitor electrically connected between the gate electrode and the electrode of the first transistor, wherein the stage is electrically connected between an electrode of the first transistor and the second power line.

[0014] An electrode of the second transistor can be connected to the gate electrode of the first transistor, the gate electrode of the second transistor is connected to the first scan line, an electrode of the third transistor is connected to the one electrode of the first transistor, and the gate electrode of the third transistor is connected to the second scan line.

[0015] Each of the first degradation coefficient and the second degradation coefficient may be a coefficient of a mathematical formula defining the luminance of the pixel reduced according to the driving time of the pixel, and the larger the coefficient is, the larger the change in luminance may be.

[0016] The second degradation coefficient of the defective pixel may be greater than the first degradation coefficient of the normal pixel.

[0017] Each of the first degradation coefficient and the second degradation coefficient may include a grayscale coefficient, a temperature coefficient, a frequency coefficient, and a light emission duty cycle coefficient, which respectively represent changes in the brightness according to grayscale value, driving temperature, driving frequency, and the light emission duty cycle of the pixel.

[0018] The compensation unit can calculate a first compensation value for compensating the grayscale value of the normal pixel based on the first degradation coefficient, and calculate a second compensation value for compensating the grayscale value of the defective pixel based on the second degradation coefficient. Under the conditions that the driving time is the same and the grayscale value in the image data is the same, the second compensation value can be greater than the first compensation value.

[0019] According to an embodiment of the present invention, a method for driving a display device is performed with the display device as an object. The display device includes pixels, each of which includes stages connected in series, and each of the stages includes a light-emitting element. The method for driving the display device may include the following steps: detecting a defective pixel among the pixels when a defect exists in the stage by applying a driving voltage to the display device; obtaining a first degradation coefficient of a normal pixel among the pixels and a second degradation coefficient of the defective pixel by driving the display device for a reference time; and storing position information of the defective pixel and the first degradation coefficient and the second degradation coefficient in a storage unit of the display device.

[0020] The first degradation coefficient may be a coefficient of a mathematical formula defining the brightness reduced according to the driving time of the normal pixel, and the second degradation coefficient is a coefficient of a mathematical formula defining the brightness reduced according to the driving time of the defective pixel. The larger the coefficient, the greater the change in brightness may be, and the second degradation coefficient of the defective pixel may be greater than the first degradation coefficient of the normal pixel.

[0021] Each of the pixels may further include the same pixel circuit for providing a driving current to the stages, the pixels may include the same number of stages as one another, and the light emitting elements of the pixels may have the same size as one another and emit light in the same color.

[0022] The step of detecting the defective pixel may include the following steps: obtaining a thermal infrared image by photographing the display device; detecting a defect level in the level where the defect occurs from the thermal infrared image; and obtaining the position information of the defective pixel based on the defect level.

[0023] Each of the pixels may include two levels, and in the step of detecting the defective pixel, only position information of the defective pixel may be obtained without obtaining position information of the normal pixel and information on the number of defective levels.

[0024] Each of the pixels may include more than three of the levels, the defective pixels may include a first defective pixel and a second defective pixel, the first defective pixel includes one defective level having the defect, and the second defective pixel includes two defective levels having the defect, and the step of detecting the first defective pixel may include the step of obtaining position information of each of the first defective pixel and the second defective pixel and quantity information of the defect levels.

[0025] Each of the first degradation coefficient and the second degradation coefficient may be a grayscale coefficient, a temperature coefficient, a frequency coefficient and a luminous duty cycle coefficient, which respectively represent the change in the brightness according to the grayscale value, the driving temperature, the driving frequency and the luminous duty cycle of the pixel. The steps of obtaining the first degradation coefficient and the second degradation coefficient may include the following steps: changing the grayscale value and obtaining the grayscale coefficient; changing the driving temperature and obtaining the temperature coefficient; changing the driving frequency and obtaining the frequency coefficient; and changing the luminous duty cycle and obtaining the luminous duty cycle coefficient.

[0026] The driving method of the display device may further include the following steps: compensating the grayscale value in the image data of a normal pixel among the pixels based on a first degradation coefficient, and compensating the grayscale value of the defective pixel based on a second degradation coefficient different from the first degradation coefficient, thereby generating compensated data; and generating a data voltage based on the compensated data, and providing the data voltage to the pixel.

[0027] According to the display device and the method for driving the display device according to the embodiments of the present invention, the grayscale values ​​of normal pixels can be compensated based on a first degradation coefficient, and the grayscale values ​​of defective pixels can be compensated based on a second degradation coefficient different from the first degradation coefficient. Therefore, the degradation of defective pixels can be compensated more accurately, and the display quality can be improved.

[0028] The effects according to the embodiment are not limited to the above-exemplified contents, and include more various effects in this specification. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0030] Figure 2 It is shown that the Figure 1 A circuit diagram of an embodiment of a pixel in a display device.

[0031] Figure 3 It shows Figure 2 A plan view of an embodiment of a pixel.

[0032] Figure 4 It is shown that the Figure 1 A circuit diagram of another embodiment of a pixel in a display device.

[0033] Figure 5 Is used to illustrate the detection Figure 1 FIG. 1 is a diagram of a method for detecting defective pixels within a display device.

[0034] Figure 6 It shows Figure 5 Graph showing degradation characteristics of pixels.

[0035] Figure 7 and Figure 8 is a diagram showing an example of a lookup table including information of defective pixels.

[0036] Figure 9 It is shown that the Figure 1 A block diagram of an embodiment of a compensation unit in a display device.

[0037] Figure 10 It is shown that the Figure 1 A circuit diagram of another embodiment of a pixel in a display device.

[0038] Figure 11 is a flowchart illustrating a method for driving a display device according to an embodiment. DETAILED DESCRIPTION

[0039] The present invention is susceptible to numerous modifications and various forms, and specific embodiments are illustrated in the accompanying drawings and described in detail herein. However, this does not limit the present invention to the specific disclosed forms, and the present invention should be understood to encompass all modifications, equivalents, and even substitutes encompassed by the concept and technical scope of the present invention.

[0040] Terms such as "first" and "second" may be used to describe various components, but the components are not limited to these terms. These terms are used only to distinguish one component from another. For example, without departing from the scope of the present invention, a first component may be named a second component, and similarly, a second component may be named a first component. Unless the context clearly indicates otherwise, expressions in the singular include expressions in the plural.

[0041] In this application, the terms "including" or "having" are used to specify the presence of features, numbers, steps, operations, constituent elements, parts or combinations thereof described in the specification, and should be understood as not excluding in advance the presence or additional possibility of one or more other features or numbers, steps, operations, constituent elements, parts or combinations thereof. In addition, when referring to a layer, film, region, plate or other part being "above" another part, this includes not only the case where it is "immediately above" the other part, but also the case where other parts exist between them. In addition, in this specification, when referring to a layer, film, region, plate or other part being formed on another part, the direction in which it is formed is not limited to the upper direction, but also includes the case where it is formed on the side surface or in the lower direction. On the contrary, when referring to a layer, film, region, plate or other part being "below" another part, this includes not only the case where it is "immediately below" the other part, but also the case where other parts exist between them.

[0042] In the following description, when a part is mentioned to be connected to another part, this includes not only the case of direct connection, but also the case of electrical connection with other components between them. In one embodiment of the present invention, the "connection" between two components can refer to both electrical connection and physical connection.

[0043] Hereinafter, a display device according to an embodiment will be described with reference to the accompanying drawings.

[0044] Figure 1 is a block diagram illustrating a display device according to an embodiment.

[0045] Reference Figure 1 The display device may include a display portion 100 (or a display panel), a scan driving portion 200 , a data driving portion 300 , a timing control portion 400 , a storage portion 500 , and a compensation portion 600 .

[0046] The term "display device" may refer to any electronic device that provides a display screen, or may be applied to any such electronic device. For example, a display device may include a television, laptop computer, monitor, billboard, IoT device, mobile phone, smartphone, tablet PC (Personal Computer), electronic watch, smartwatch, watch phone, head-mounted display, mobile communication terminal, electronic notepad, e-book, portable multimedia player (PMP), navigation system, game console, digital camera, video camera, etc. that provides a display screen.

[0047] The display device may be implemented as a self-luminous display device including a plurality of self-luminous elements. For example, the display device may be an inorganic light-emitting display device including inorganic light-emitting elements. However, the display device is not limited thereto and may be an organic light-emitting display device including organic light-emitting elements, or a display device including light-emitting elements composed of a combination of inorganic and organic substances.

[0048] The display unit 100 may include a pixel PX (or a plurality of pixels) connected to a data line DL, a first scan line SL, a second scan line SSL, and a sensing line RL. The display unit 100 (or pixel PX) may receive a first driving voltage VDD, a second driving voltage VSS, and an initialization voltage from the outside. The specific structure of the pixel PX will be described below with reference to Figure 2 Provide explanation.

[0049] The scan driver 200 can supply a first scan signal to the first scan line SL and a second scan signal to the second scan line SSL in response to a scan control signal SCS. The scan control signal SCS may include a scan start signal (or start pulse), a scan clock signal, and the like, and may be provided to the scan driver 200 from the timing control unit 400. For example, the scan driver 200 may include a shift register that uses the scan clock signal to sequentially generate and output a pulse-shaped first scan signal and / or second scan signal corresponding to a pulse-shaped scan start signal (e.g., a pulse at a gate-on voltage level that turns on a transistor).

[0050] The data driver 300 can generate a data signal (or data voltage) based on the data control signal DCS and the compensated data DATA2, and provide the data signal to the data line DL. The data control signal DCS is a signal provided by the timing control unit 400 to control the operation of the data driver 300, and can include a load signal (or data enable signal) indicating the output of a valid data voltage. The compensated data DATA2 can be provided by the compensation unit 600.

[0051] In one embodiment, the data driver 300 may generate a data signal corresponding to the data value (or grayscale value) included in the compensated data DATA2 using gamma voltages. The gamma voltages may be generated within the data driver 300 or provided from a separate gamma voltage generating circuit (e.g., a gamma integrated circuit). For example, the data driver 300 may select one of the gamma voltages based on the data value and output it as the data signal.

[0052] The data driving unit 300 may supply an initialization voltage to the sensing line RL during a display period (i.e., a period during which the display unit 100 displays an image). Furthermore, the data driving unit 300 may sense the light emission characteristics of the pixel PX via the sensing line RL during a sensing period. The light emission characteristics of the pixel PX may include the threshold voltage and mobility of at least one transistor (e.g., a driving transistor) in the pixel PX, as well as characteristic information of the light emitting element (e.g., current-voltage characteristics).

[0053] The sensing line RL is shown as being connected to the data driving part 300 , but is not limited thereto. For example, a sensing part (or sensing circuit) independent of the data driving part 300 may also be connected to the sensing line RL.

[0054] The timing control unit 400 may receive a control signal CTL and image signals RGB from an external processor, such as a graphics device. The timing control unit 400 may generate a data control signal DCS and a scan control signal SCS in response to the control signal CTL. The timing control unit 400 may supply image data DATA1 to the compensation unit 600, which rearranges the image signals RGB to match the arrangement of pixels PX in the display unit 100.

[0055] The storage unit 500 may include the position information of the defective pixel. Figure 2 ) has a defect (e.g., a short circuit), or the defective portion has been repaired (e.g., removed) and at least some of the light-emitting elements in the portion of the stage fail to emit light normally or do not emit light, the pixel PX may be referred to as a defective pixel (or defective pixel). Furthermore, pixels PX without defects in stages SET1 and SET2 may be referred to as normal pixels.

[0056] According to an embodiment, in the case where the pixel PX includes three or more levels, in addition to the position information of the defective pixel, the storage unit 500 may also include the number information of the defective levels (i.e., the level where the defect occurs) of the defective pixel or information corresponding thereto (e.g., the number information of normal levels).

[0057] In addition, the storage unit 500 may also include lifespan data representing the drive time (or cumulative drive time) of the pixel PX. The drive time refers to the cumulative drive time of the pixel PX after manufacturing the display device, and may be the same as or proportional to the value obtained by multiplying the grayscale value for the pixel PX in the compensated data DATA2 by the time it was driven at that grayscale value. For example, the drive time may further reflect a weighted value based on the drive temperature of the display device, a weighted value based on the drive frequency of the display device, a weighted value based on the luminous duty cycle of the pixel PX, and the like. For example, the drive time may be calculated as being longer when the drive temperature is higher, the drive frequency is higher, or the luminous duty cycle is larger.

[0058] The storage unit 500 can be implemented as a non-volatile storage device such as an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory, a phase change random access memory (PRAM), a resistance random access memory (RRAM), a nano floating gate memory (NFGM), a polymer random access memory (PoRAM), a magnetic random access memory (MRAM), or a ferroelectric random access memory (FRAM).

[0059] Compensation unit 600 can compensate the grayscale value for pixel PX within image data DATA1 based on the degradation coefficient, thereby generating compensated data DATA2. Here, the degradation coefficient (or degradation constant, or lifetime acceleration coefficient) is a coefficient of a mathematical formula (or degradation curve, or lifetime curve) that defines or predicts the decrease in brightness of pixel PX as a function of the driving time of pixel PX. A larger coefficient indicates a greater change in brightness. For example, the mathematical formula can be a stretched exponential function, but is not limited thereto.

[0060] For example, a degradation curve representing the luminance of a pixel PX that decreases according to the driving time of the pixel PX may be defined by Mathematical Formula 1 below.

[0061] [Mathematical formula 1]

[0062]

[0063] Here, L(t) may be the reduced luminance (or estimated luminance) according to the driving time t of pixel PX. For example, it may be the ratio of the reduced luminance to the initial maximum luminance of pixel PX. t may be the driving time of pixel PX. τ and β may be experimentally determined degradation coefficients.

[0064] In one embodiment, the compensation unit 600 may compensate the grayscale values ​​for normal pixels based on a first degradation coefficient, and may compensate the grayscale values ​​for defective pixels corresponding to the position information based on a second degradation coefficient different from the first degradation coefficient. For example, the compensation unit 600 may compensate the grayscale values ​​within the image data DATA1 based on the first degradation coefficient, and may compensate the grayscale values ​​within the image data DATA1 corresponding to the position information based on the second degradation coefficient. For example, the compensation unit 600 may calculate a first compensation value for compensating the grayscale values ​​of normal pixels based on the first degradation coefficient, and may calculate a second compensation value for compensating the grayscale values ​​of defective pixels based on the second degradation coefficient. Under the conditions of the same driving time and the same grayscale values ​​within the image data DATA1, the second compensation value may be greater than the first compensation value.

[0065] As described below, for the same grayscale value (or the same brightness), a relatively higher voltage and / or driving current may be applied to the light-emitting element of the defective pixel compared to the normal pixel, and the defective pixel may degrade faster than the normal pixel. As the degradation of the defective pixel accelerates, the degradation characteristics of the defective pixel may become worse than the degradation characteristics of the normal pixel. In this case, even if the defective pixel and the normal pixel are structurally identical (for example, even if the pixel circuits of the defective pixel and the normal pixel are the same, and the size, number, color, etc. of the light-emitting elements equipped in the defective pixel and the normal pixel are substantially the same), it may be difficult to define the degradation characteristics of the defective pixel and the degradation characteristics of the normal pixel using only one mathematical formula (or one degradation coefficient). Therefore, the compensation unit 600 can additionally include a second degradation coefficient that is different from the first degradation coefficient used for the normal pixel, and the second degradation coefficient can be used to compensate for the degradation of the defective pixel.

[0066] Since defective pixels degrade faster than normal pixels, the second degradation coefficient for the defective pixels may be greater than the first degradation coefficient for the normal pixels, but is not limited thereto.

[0067] The first degradation coefficient and the second degradation coefficient may be stored in the compensation unit 600, but are not limited thereto. For example, the first degradation coefficient and the second degradation coefficient may be stored in the storage unit 500 and may also be loaded into the compensation unit 600. As another example, instead of the first degradation coefficient, the relationship between the grayscale value (i.e., the grayscale value before compensation) and the grayscale value after compensation may be stored as a lookup table in the compensation unit 600 or the storage unit 500 for each driving time based on the first degradation coefficient. Similarly, a lookup table based on the second degradation coefficient may also be stored in the compensation unit 600 or the storage unit 500.

[0068] As described above, the display device (or compensation unit 600) can compensate the grayscale values ​​of normal pixels based on a first degradation coefficient, and can compensate the grayscale values ​​of defective pixels based on a second degradation coefficient that is different from the first degradation coefficient. Therefore, the degradation of defective pixels can be compensated more accurately, and display quality can be improved.

[0069] In addition, Figure 1 , the scan driver 200, the data driver 300, the timing control unit 400, and the compensation unit 600 are shown as being independently configured. However, this is merely exemplary and not limiting. For example, at least one of the scan driver 200, the data driver 300, the timing control unit 400, and the compensation unit 600 may be incorporated into the display unit 100, or may be implemented as an integrated circuit. For example, the scan driver 200 may be incorporated into the display unit 100. For example, at least two of the scan driver 200, the data driver 300, the timing control unit 400, and the compensation unit 600 may be implemented as a single integrated circuit.

[0070] Figure 2 It is shown that the Figure 1 A circuit diagram of an embodiment of a pixel in a display device. Figure 1 The pixels PX (i.e., normal pixels and defective pixels) in the display device can be identical to each other, for example, the pixel circuit PXC, the structure / size of the light-emitting unit EMU, the size, number, and color of the light-emitting element LD of each pixel PX (i.e., normal pixels and defective pixels) can be identical.

[0071] Reference Figure 2 The pixel PX may include a light emitting unit EMU that generates light with brightness corresponding to the data signal. In addition, the pixel PX may further selectively include a pixel circuit PXC for driving the light emitting unit EMU.

[0072] The light-emitting unit EMU may include a plurality of light-emitting elements LD connected in parallel between a first power line PL1 to which a first driving voltage VDD is applied and a second power line PL2 to which a second driving voltage VSS is applied. For example, the light-emitting unit EMU may include a first electrode EL1 connected to the first power line PL1 via a pixel circuit PXC, a third electrode EL3 connected to the second power line PL2, and a plurality of light-emitting elements LD connected in parallel between the first electrode EL1 and the third electrode EL3 in the same direction. In one embodiment of the present invention, the first electrode EL1 may be an anode electrode, and the third electrode EL3 may be a cathode electrode.

[0073] Each of the light emitting elements LD included in the light emitting unit EMU may include one end connected to the first power line PL1 through the first electrode EL1 and the other end connected to the second power line PL2 through the third electrode EL3 .

[0074] The light-emitting element LD connected in parallel in the same direction between the first electrode EL1 and the third electrode EL3, which are supplied with different potentials (i.e., the first driving voltage VDD and the second driving voltage VSS), can constitute an effective light source. Such effective light sources can be aggregated to form the light-emitting unit EMU of the pixel PX.

[0075] The light emitting element LD of the light emitting unit EMU may emit light at a brightness corresponding to the driving current ID supplied by the corresponding pixel circuit PXC. For example, during each frame period, the pixel circuit PXC may supply the light emitting unit EMU with the corresponding frame data (for example, the compensated data DATA2 (refer to FIG. Figure 1 )) corresponding to the grayscale value of the driving current ID. The driving current ID supplied to the light-emitting unit EMU can be divided and flowed through each light-emitting element LD. Accordingly, each light-emitting element LD can emit light at a brightness corresponding to the current flowing therethrough, and the light-emitting unit EMU can emit light at a brightness corresponding to the driving current ID.

[0076] In addition to the light-emitting elements LD that constitute each effective light source, the light-emitting unit EMU may further include at least one inactive light source, exemplified by a reverse light-emitting element LDr. The reverse light-emitting element LDr may be connected in parallel with the light-emitting elements LD that constitute the effective light source, between the first electrode EL1 and the third electrode EL3, and connected in a direction opposite to (or with a different polarity than) that of the light-emitting elements LD. Even when a predetermined drive voltage (exemplified by a forward drive voltage) is applied between the first electrode EL1 and the third electrode EL3, the reverse light-emitting element LDr remains in an inactive state, and thus substantially no current flows through the reverse light-emitting element LDr.

[0077] The pixel circuit PXC may be connected to the first scan line SL, the second scan line SSL, the data line DL, and the sensing line RL of the corresponding pixel PX.

[0078] According to an embodiment, the pixel circuit PXC may include a first transistor T1, a second transistor T2, a third transistor T3, and a storage capacitor Cst. However, the structure of the pixel circuit PXC is not limited to Figure 2 The embodiment shown.

[0079] A first terminal (or first electrode) of a first transistor T1 (driving transistor) may be connected to a first power line PL1, and a second terminal (or second electrode) may be connected to a second node N2 (or first electrode EL1). A gate electrode of the first transistor T1 may be connected to a first node N1. The first transistor T1 described above can control the amount of driving current ID supplied to the light emitting unit EMU in response to the voltage of the first node N1.

[0080] A second transistor T2 (switching transistor) may have a first terminal connected to the data line DL, and a second terminal connected to the first node N1. A gate electrode of the second transistor T2 may be connected to the first scan line SL. The second transistor T2 may be turned on when a first scan signal SC, which provides a gate-on voltage (e.g., a high voltage) that turns on the second transistor T2, is supplied from the first scan line SL, thereby electrically connecting the data line DL to the first node N1. At this time, a data signal Vdata of the corresponding frame may be supplied to the data line DL, thereby transmitting the data signal Vdata to the first node N1. The data signal Vdata transmitted to the first node N1 may charge the storage capacitor Cst.

[0081] One electrode of the storage capacitor Cst may be connected to the first node N1, and the other electrode may be connected to the second node N2. The storage capacitor Cst may be charged with a voltage corresponding to the data signal Vdata supplied to the first node N1 and maintain the charged voltage until the data signal Vdata of the next frame is supplied.

[0082] The first terminal of the third transistor T3 (sensing transistor) can be connected to the second node N2, and the second terminal can be connected to the sensing line RL. The gate electrode of the third transistor T3 can be connected to the second scan line SSL. Alternatively, if the sensing line RL is omitted, the second terminal of the third transistor T3 can be connected to the data line DL. If the second scan line SSL is omitted, the gate electrode of the third transistor T3 can also be connected to the first scan line SL. As described above, the third transistor T3 can be turned on during a predetermined sensing period by the second scan signal SS supplying a gate-on voltage to the second scan line SSL, thereby electrically connecting the sensing line RL to the second node N2.

[0083] exist Figure 2 , the first transistor T1, the second transistor T2, and the third transistor T3 are all n-type transistors, but the present invention is not limited thereto. For example, at least one of the first transistor T1, the second transistor T2, and the third transistor T3 may be changed to a p-type transistor. Figure 2 , the light emitting unit EMU is connected between the pixel circuit PXC and the second power line PL2 , but the light emitting unit EMU may also be connected between the first power line PL1 and the pixel circuit PXC.

[0084] The light-emitting unit EMU may include a first stage SET1 (or a first stack, a first sub-light-emitting unit, and a first element group) and a second stage SET2 (or a second stack, a second sub-light-emitting unit, and a second element group) sequentially connected between a first power line PL1 and a second power line PL2. The light-emitting unit EMU may include a first electrode EL1, a second electrode EL2, a third electrode EL3, and a fourth electrode EL4. The first stage SET1 and the second stage SET2 may each include a plurality of light-emitting elements LD connected in parallel along the same direction between two electrodes EL1 to EL4.

[0085] The first stage SET1 may include a first electrode EL1 and a second electrode EL2 (or a first sub intermediate electrode CTE- 1 ), and may include at least one first light emitting element LD1 connected between the first electrode EL1 and the second electrode EL2 (or the first sub intermediate electrode CTE- 1 ).

[0086] The second stage SET2 may include a fourth electrode EL4 (or a second sub intermediate electrode CTE- 2 ) and a third electrode EL3 , and may include at least one second light emitting element LD2 connected between the fourth electrode EL4 (or a second sub intermediate electrode CTE- 2 ) and the third electrode EL3 .

[0087] The first sub-intermediate electrode CTE-1 of the first-stage SET1 and the second sub-intermediate electrode CTE-2 of the second-stage SET2 can be integrally provided and connected to each other. That is, the first sub-intermediate electrode CTE-1 and the second sub-intermediate electrode CTE-2 can constitute the intermediate electrode CTE that electrically connects the first-stage SET1 and the second-stage SET2. When the first sub-intermediate electrode CTE-1 and the second sub-intermediate electrode CTE-2 are integrally provided, the first sub-intermediate electrode CTE-1 and the second sub-intermediate electrode CTE-2 can be different regions of the intermediate electrode CTE.

[0088] In the above embodiment, the first electrode EL1 may be an anode electrode of the light emitting unit EMU of each pixel PX, and the third electrode EL3 may be a cathode electrode of the light emitting unit EMU.

[0089] As described above, the light emitting unit EMU of the pixel PX including the light emitting elements LD connected in a series / parallel hybrid structure can easily adjust the driving current ID and / or voltage conditions according to applicable product specifications.

[0090] In particular, the light emitting unit EMU of the pixel PX including the light emitting elements LD connected in a series / parallel hybrid structure can reduce the driving current ID compared to the light emitting unit EMU having a structure in which the light emitting elements LD are connected only in parallel.

[0091] In addition, Figure 2 FIG shows a case where the pixel PX (or the light emitting unit EMU) includes two stages (ie, the first stage SET1 and the second stage SET2), but is not limited thereto. For example, the pixel PX may include more than three stages, which will be referred to in FIG. Figure 10 This will be described later.

[0092] Figure 3 It shows Figure 2 For ease of explanation, except for Figure 2 The pixel circuit PXC is included in the pixel PXC and the light emitting unit EMU is shown as the center. Figure 1 The light emitting units EMU of the pixels PX in the display device (ie, the light emitting units EMU of the normal pixels and the light emitting units EMU of the defective pixels) are identical to each other and can be Figure 3 The same as the embodiment.

[0093] Reference Figure 2 and Figure 3Pixel PX may be formed in a pixel area PXA defined on a substrate. Pixel area PXA may include an emission area EMA. According to an embodiment, pixel PX may include a bank BNK and may be defined by the bank BNK surrounding the emission area EMA. The bank BNK may include a first opening OP1 and a second opening OP2 exposing a lower portion. The emission area EMA may be defined by the first opening OP1 of the bank BNK.

[0094] The first electrode EL1, the second electrode EL2, the third electrode EL3, and the fourth electrode EL4 may be arranged sequentially along a first direction DR1. Each of the first electrode EL1, the second electrode EL2, the third electrode EL3, and the fourth electrode EL4 may extend along a second direction DR2 that intersects the first direction DR1. Ends of the first electrode EL1, the second electrode EL2, the third electrode EL3, and the fourth electrode EL4 may be located within the second opening OP2 of the bank BNK. For reference, during the manufacturing process of the display device, the first electrode EL1, the second electrode EL2, the third electrode EL3, and the fourth electrode EL4 may extend to an adjacent pixel region before the light-emitting element LD is supplied to the substrate. After the light-emitting element LD is supplied and arranged in the pixel region PXA, it may be separated from other electrodes (e.g., electrodes of adjacent pixels adjacent in the second direction DR2) within the second opening OP2.

[0095] The first electrode EL1 can be connected to the reference electrode through the first contact hole CNT1. Figure 2 The third electrode EL3 can be connected to the reference transistor T1 through the second contact hole CNT2. Figure 2 The second power supply line PL2 is connected.

[0096] Depending on the embodiment, each of the first electrode EL1, the second electrode EL2, the third electrode EL3, and the fourth electrode EL4 may have a single-layer structure or a multi-layer structure. As an example, the first electrode EL1, the second electrode EL2, the third electrode EL3, and the fourth electrode EL4 may have a multi-layer structure including a reflective electrode and a conductive cover layer. Furthermore, the reflective electrode may have a single-layer structure or a multi-layer structure. As an example, the reflective electrode may include at least one reflective conductive layer and may optionally include at least one transparent conductive layer disposed above and / or below the reflective conductive layer.

[0097] According to an embodiment, the pixel PX may include a first bank pattern BNKP1 overlapping an area of ​​the first electrode EL1, a second bank pattern BNKP2 overlapping an area of ​​the second electrode EL2, a third bank pattern BNKP3 overlapping an area of ​​the third electrode EL3, and a fourth bank pattern BNKP4 overlapping an area of ​​the fourth electrode EL4.

[0098] The first bank pattern BNKP1, the second bank pattern BNKP2, the third bank pattern BNKP3, and the fourth bank pattern BNKP4 may be spaced apart from each other in the light emitting area EMA and may cause a region of each of the first electrode EL1, the second electrode EL2, the third electrode EL3, and the fourth electrode EL4 to protrude upward. For example, the first electrode EL1 (or a protruding portion of the first electrode EL1) may be arranged on the first bank pattern BNKP1 so as to protrude in a third direction DR3 (i.e., the thickness direction of the substrate) via the first bank pattern BNKP1. The second electrode EL2 may be arranged on the second bank pattern BNKP2 so as to protrude in the third direction DR3 via the second bank pattern BNKP2. The third electrode EL3 may be arranged on the third bank pattern BNKP3 so as to protrude in the third direction DR3 via the third bank pattern BNKP3. The fourth electrode EL4 (or a protruding portion of the fourth electrode EL4) may be arranged on the fourth bank pattern BNKP4 so as to protrude in the third direction DR3 via the fourth bank pattern BNKP4. The second bank pattern BNKP2 and the third bank pattern BNKP3 may also be formed as one body without being separated from each other.

[0099] The first light emitting element LD1 may be arranged between the first electrode EL1 and the second electrode EL2. The first end (or one end) of the first light emitting element LD1 may face the first electrode EL1, and the second end (or the other end) of the first light emitting element LD1 may face the second electrode EL2. In the case where a plurality of first light emitting elements LD1 are provided, the first light emitting elements LD1 may be connected in parallel between the first electrode EL1 and the second electrode EL2, and may constitute a reference electrode. Figure 2 The first level SET1 is described.

[0100] Similarly, the second light-emitting element LD2 can be arranged between the third electrode EL3 and the fourth electrode EL4. The first end of the second light-emitting element LD2 can face the fourth electrode EL4, and the second end of the second light-emitting element LD2 can face the third electrode EL3. The second end of the second light-emitting element LD2 and the second end of the first light-emitting element LD1 can include the same type of semiconductor layer (for example, a p-type semiconductor layer) and can face each other with the second electrode EL2 and the third electrode EL3 interposed therebetween. In the case of providing a plurality of second light-emitting elements LD2, the second light-emitting elements LD2 can be connected in parallel between the third electrode EL3 and the fourth electrode EL4, and can constitute a reference Figure 2 The second level SET2 is described.

[0101] According to an embodiment, the first light emitting element LD1 and the second light emitting element LD2 may each be an ultra-small (for example, nanometer to micrometer-sized) light emitting diode using an inorganic crystalline material.

[0102] According to embodiments, the light-emitting element LD can be prepared in a form dispersed in a predetermined solution and supplied to the light-emitting area EMA of the pixel area PXA by inkjet printing or slit coating. As an example, the light-emitting element LD can be mixed with a volatile solvent and supplied to the light-emitting area EMA. In this case, if a predetermined voltage is applied between the first electrode EL1 and the second electrode EL2, and between the third electrode EL3 and the fourth electrode EL4, an electric field can be formed between the first electrode EL1 and the second electrode EL2, and between the third electrode EL3 and the fourth electrode EL4, thereby adaptively aligning the light-emitting element LD between the first electrode EL1, the second electrode EL2, the third electrode EL3, and the fourth electrode EL4. After aligning the light-emitting element LD, the solvent is removed by volatilization or other methods, so that the light-emitting element LD can be stably arranged between the first electrode EL1 and the second electrode EL2, and between the third electrode EL3 and the fourth electrode EL4.

[0103] According to an embodiment, the pixel PX may include a first contact electrode CNE1 , a second contact electrode CNE2 , and an intermediate electrode CTE.

[0104] The first contact electrode CNE1 may be formed on the first end portion of the first light emitting element LD1 and at least a region of the first electrode EL1 corresponding to the first end portion, thereby physically and / or electrically connecting the first end portion of the first light emitting element LD1 to the first electrode EL1.

[0105] The second contact electrode CNE2 may be formed on the second end of the second light emitting element LD2 and at least a region of the third electrode EL3 corresponding to the second end, thereby physically and / or electrically connecting the second end of the second light emitting element LD2 to the third electrode EL3.

[0106] The intermediate electrode CTE may include a first sub-intermediate electrode CTE-1 (or first intermediate electrode) and a second sub-intermediate electrode CTE-2 (or second intermediate electrode) extending along the second direction DR2. The first sub-intermediate electrode CTE-1 may be formed on the second end of the first light-emitting element LD1 and at least a region of the second electrode EL2 corresponding to the second end. The intermediate electrode CTE may extend from the first sub-intermediate electrode CTE-1, bypassing the second contact electrode CNE2 or the second light-emitting element LD2. The second sub-intermediate electrode CTE-2 may be formed on the first end of the second light-emitting element LD2 and at least a region of the fourth electrode EL4 corresponding to the first end. The intermediate electrode CTE may electrically connect the second end of the first light-emitting element LD1 with the first end of the second light-emitting element LD2.

[0107] Figure 4 It is shown that the Figure 1 A circuit diagram of another embodiment of a pixel in a display device. Figure 4 , a circuit diagram of a defective pixel PX_F is shown in FIG.

[0108] Reference Figure 2 and Figure 4 , except that there is a defect in the first stage SET1 (or the first light emitting element LD1), the defective pixel PX_F can be Figure 2 The pixels PX (or normal pixels) are substantially the same. Therefore, repeated description will not be repeated. The defect in the first stage SET1 is exemplary. For example, a defect may also exist in the second stage SET2 (or the second light-emitting element LD2) instead of the first stage SET1.

[0109] For example, the first electrode EL1 and the second electrode EL2 may have Figure 4 In this case, the driving current ID flowing between the first electrode EL1 and the second electrode EL2 passes through the defective first light emitting element LD1 and may not flow through other first light emitting elements LD1 that require an operating voltage.

[0110] For reference, when the first light-emitting element LD1 is disconnected (open), only the first light-emitting element LD1 has no current flowing through it, while the current can flow through the other first light-emitting elements LD1, so the display quality is hardly degraded. As the number of first light-emitting elements LD1 increases, the disconnection of one first light-emitting element LD1 may have almost no effect on the first stage SET1. In contrast, when the first light-emitting element LD1 is short-circuited, the first stage SET1 does not operate (or emit light), and the brightness of the pixel PX may be significantly reduced (for example, reduced to 1 / 2 level). Figure 2 The pixel PX and Figure 4 When the same data signal Vdata is applied to the defective pixel PX_F, Figure 4 The defective pixel PX_F can be compared with Figure 2 The pixel PX emits light with a low brightness. Figure 1 ) When equipped with multiple defective pixels PX_F, brightness deviation may occur and the display quality may be reduced.

[0111] Therefore, by detecting defective pixels PX_F and ensuring that they emit at the same brightness as normal pixels (or pixels PX), degradation in display quality can be prevented. For example, for the same grayscale value, the data signal Vdata (or drive current ID) applied to the defective pixel PX_F can be increased compared to normal pixels, thereby ensuring that the brightness of the defective pixel PX_F is the same as that of normal pixels. However, as the current flowing through the light-emitting element LD increases, the defective pixel PX_F may degrade faster than normal pixels.

[0112] As another example, to eliminate a short circuit caused by a defective first light-emitting element LD1, a defective pixel PX_F can be repaired by cutting off at least one of the defective first light-emitting element LD1, the first electrode EL1, and the second electrode EL2. Given the small size of the light-emitting element LD, it is difficult to directly remove only the defective first light-emitting element LD1. To improve the repair efficiency of the defective pixel PX_F, the first electrode EL1 and / or the second electrode EL2 can be partially cut off (e.g., cut in half). In this case, the drive current ID can be split to flow through only a portion (e.g., half) of the first light-emitting element LD1 of the first stage SET1 of the defective pixel PX_F. In other words, a relatively high current can flow through only a portion (e.g., half) of the first light-emitting element LD1 of the first stage SET1 of the defective pixel PX_F. Even without increasing the data signal Vdata (or drive current ID), the defective pixel PX_F can still emit light at the target brightness. However, the high current flowing through each first light-emitting element LD1 may cause rapid degradation of the defective pixel PX_F.

[0113] As described above, the defective pixel PX_F may include a short-circuit defect portion or a short-circuit defect repaired portion in one of the stages SET1 ˜ SET2 , in which case the defective pixel PX_F may deteriorate faster than a normal pixel.

[0114] Alternatively, a short circuit failure may occur in all stages SET1 to SET2 . However, in this case, since the pixel (or light emitting unit EMU) does not emit light, the pixel may not be considered as a target for degradation compensation.

[0115] Figure 5 Is used to illustrate the detection Figure 1 FIG. 1 is a diagram of a method for detecting defective pixels within a display device.

[0116] Reference Figure 5 , a driving voltage may be applied to the display portion 100 (or display device), and the pixel PX may emit light. The driving current ID (refer to Figure 2 ) can be separated and flow through the light emitting element LD in the pixel PX ( Figure 2) (or level), and the light emitting element LD can emit light and release heat.

[0117] The inspection device 50 (or photographing device) may be disposed at a predetermined angle so as to be able to photograph the entire area of ​​the front surface of the display portion 100 .

[0118] The inspection device 50 may include a thermal imaging camera, a charge-coupled device (CCD) camera, etc. The inspection device 50 may photograph the display unit 100 (or the display device) to obtain a thermal infrared image or temperature data.

[0119] If the temperature of a region corresponding to a specific level (e.g., the first level SET1) in the thermal infrared image appears low (e.g., lower than the average temperature of the entire display unit 100), it can be determined that current is not flowing in the light-emitting elements within the corresponding level (i.e., a defect has occurred in the corresponding level). Furthermore, based on the position of the region (i.e., the low-temperature region) within the thermal infrared image, the defective level (i.e., the level where the defect has occurred) and the defective pixel PX_F containing it can be specified. In other words, the position information of the defective pixel PX_F can be obtained.

[0120] The position information of the defective pixel PX_F may be provided to the storage part 500 , and the storage part 500 may store the position information of the defective pixel PX_F.

[0121] Figure 6 It shows Figure 5 Graph showing degradation characteristics of pixels. Figure 6 , a first degradation curve CURVE1 for a pixel PX (or a normal pixel) and a second degradation curve CURVE2 for a defective pixel PX_F are shown. Each of the first degradation curve CURVE1 and the second degradation curve CURVE2 represents a luminance change (or luminance reduction rate) according to a driving time (or cumulative driving time).

[0122] Reference Figure 5 and Figure 6 The display unit 100 (or display device) may be driven at a reference time and the luminance of the display unit 100 may be periodically measured by the inspection device 50. That is, the first degradation curve CURVE1 and the second degradation curve CURVE2 may be obtained through experiments.

[0123] A first degradation coefficient may be calculated or obtained based on the first degradation curve CURVE1 and Mathematical Formula 1. The first degradation coefficient may correspond to the slope of the first degradation curve CURVE1. Similarly, a second degradation coefficient may be obtained based on the second degradation curve CURVE2 and Mathematical Formula 1. The second degradation coefficient may correspond to the slope of the second degradation curve CURVE2 and may be greater than the first degradation coefficient.

[0124] In addition, the compensation portion 600 (see Figure 1 ) can calculate a first degradation curve CURVE1 based on the first degradation coefficient (i.e., the brightness reduced within a specific driving time), and can compensate the grayscale value of the pixel PX based on the difference between the target brightness according to the reference curve CURVE0 and the reduced brightness (i.e., the amount of insufficient brightness). Similarly, the compensation unit 600 can calculate a second degradation curve CURVE2 based on the second degradation coefficient (i.e., the brightness reduced within a specific driving time), and can compensate the grayscale value of the defective pixel PX_F based on the difference between the target brightness according to the reference curve CURVE0 and the reduced brightness (i.e., the amount of insufficient brightness).

[0125] In one embodiment, each of the first degradation coefficient and the second degradation coefficient may include a grayscale coefficient, a temperature coefficient, a frequency coefficient, and a light emission duty cycle coefficient, respectively representing changes in brightness according to grayscale value, driving temperature, driving frequency, and light emission duty cycle of the pixel. The grayscale coefficient, temperature coefficient, frequency coefficient, and light emission duty cycle coefficient included in the second degradation coefficient may be different from the grayscale coefficient, temperature coefficient, frequency coefficient, and light emission duty cycle coefficient included in the first degradation coefficient, respectively. However, this is not limited to this.

[0126] For example, a degradation curve representing the driving time, grayscale value, driving temperature, driving frequency, and luminance of a pixel reduced according to the light emission duty ratio of the pixel may be defined by the following Mathematical Formula 2.

[0127] [Mathematical formula 2]

[0128]

[0129] Where L can be the reduced brightness (or estimated brightness), for example, the ratio of the reduced brightness to the initial maximum brightness of the pixel (normal or defective). G can be the grayscale value for the pixel, T can be the driving temperature, F can be the driving frequency, and D can be the emission duty cycle. τ1 and β1 can be grayscale coefficients, τ2 and β2 can be temperature coefficients, τ3 and β3 can be frequency coefficients, and τ4 and β4 can be emission duty cycle coefficients.

[0130] For example, the gamma coefficient can be obtained by measuring the luminance of the display unit 100 using the inspection device 50 or performing experiments while changing the grayscale values ​​of the pixels or setting the grayscale values ​​of each pixel to different values. Similarly, the temperature coefficient can be obtained by performing experiments while changing the drive temperature of the display unit 100 (or display device) or setting the drive temperature of each display unit 100 to different values. The frequency coefficient can be obtained by performing experiments while changing the drive frequency of the display unit 100 (or display device) or the drive frequency of each display unit 100. The emission duty cycle coefficient can be obtained by performing experiments while changing the emission duty cycle of the pixels or setting the emission duty cycle of each pixel to different values.

[0131] In addition, the compensation portion 600 (see Figure 1 ) can compensate the grayscale value of a pixel (normal pixel or defective pixel) by considering the grayscale coefficient, temperature coefficient, frequency coefficient, and luminous duty cycle coefficient.

[0132] Figure 7 and Figure 8 is a diagram showing an example of a lookup table including information of defective pixels.

[0133] First, refer to Figure 1 、 Figure 7 and Figure 8 , the information of the defective pixels may be stored in the storage unit 500 in the form of a lookup table.

[0134] In one embodiment, the lookup table LUT may include defect information for each pixel.

[0135] Reference Figure 7 For example, the first information INFO_P1 indicates whether the pixel located in the first row and first column is defective, and a value of 0 may indicate no defect. The second information INFO_P2 indicates whether the pixel located in the first row and second column is defective, and a value of 1 may indicate that a defect exists in a level. In this way, the lookup table LUT can include defect information for each pixel.

[0136] In an embodiment, the lookup table LUT may include position information of a defective pixel for each specific area of ​​the display portion 100 .

[0137] In one embodiment, the lookup table LUT may include position information indicating the row where the defective pixel is located in units of columns. Figure 8For example, the first position information INFO_S1 may refer to the row where the defective pixel is located among the pixels located in the first column, and the second position information INFO_S2 may refer to the row where the defective pixel is located among the pixels located in the second column. For example, a value of A may mean that the defective pixel is located in row A, and a value of B may mean that the defective pixel is located in row B. In addition, a value of 0 may mean that there is no defective pixel. Figure 7 Compared to the lookup table LUT, Figure 8 Unnecessary information (eg, information about normal pixels) can be reduced in the lookup table LUT, and thus the capacity of the storage unit 500 for storing the lookup table LUT can be reduced.

[0138] In another embodiment, the lookup table LUT may include position information indicating the column where the defective pixel is located in units of rows. Figure 8 For example, the first position information INFO_S1 may indicate the column where the defective pixel is located among the pixels in the first row. When the number of rows is smaller than the number of columns, the size of the lookup table LUT and the capacity of the storage unit 500 can be further reduced.

[0139] In another embodiment, the lookup table LUT may include position information of defective pixels in units of blocks. A block may include M rows×N columns of pixels, and the size of the block may be set based on the frequency of generation of defective pixels. M and N may be integers greater than 1. For example, if a defective pixel is generated approximately every 2000 pixels (or 40×50 pixels) on average, the block may have a size of 40 rows×50 columns. Figure 8 For example, the first position information INFO_S1 may refer to the position of the defective pixel in the first block. Since the blocks are set based on the generation frequency of the defective pixels, the size of the lookup table LUT and the capacity of the storage unit 500 can be minimized.

[0140] In addition, although the case of including only the position information of the defective pixel (for example, the case of not including the position information of the normal pixel and the number information of the defect level) has been described, Figure 8 For example, the lookup table LUT may further include information on the number of defect levels of defective pixels. Figure 8 For example, the value in the brackets may indicate the number of defect levels, a value of 1 in the brackets may indicate that the defective pixel includes one defect level, and a value of 2 in the brackets may indicate that the defective pixel includes two defect levels.

[0141] Figure 9 It is shown that the Figure 1 A block diagram of an embodiment of a compensation unit in a display device.

[0142] Reference Figure 1 and Figure 9 The compensation unit 600 may include an accumulator 610 (or an accumulation circuit, a pressure calculation unit, a driving time calculation unit), a memory 620 (or a memory device, a storage circuit), and a compensator 630 (or a compensation circuit).

[0143] The accumulator 610 may calculate a driving time (or an accumulated driving time, an accumulated pressure) of each pixel PX based on the compensated data DATA2 .

[0144] For example, the accumulator 610 may calculate a first driving time of a normal pixel by accumulating a first compensated grayscale value GRAY1′ (or a first converted grayscale value) included in the compensated data DATA2, and may calculate a second driving time of a defective pixel by accumulating a second compensated grayscale value GRAY2′ (or a second converted grayscale value) included in the compensated data DATA2. Here, the first compensated grayscale value GRAY1′ may be a grayscale value converted from the first grayscale value GRAY1 corresponding to the first pixel through degradation compensation, and similarly, the second compensated grayscale value GRAY2′ may be a grayscale value converted from the second grayscale value GRAY2 corresponding to the second pixel through degradation compensation.

[0145] For example, the accumulator 610 may accumulate the first compensated grayscale value GRAY1' for each frame or average and reduce the first compensated grayscale value GRAY1' output during a specific time period to calculate the first drive time for the normal pixel. The accumulator 610 may add the first drive time to the first accumulated grayscale value GRAY_AC1 or update the first accumulated grayscale value GRAY_AC1 based on the first drive time. Here, the first accumulated grayscale value GRAY_AC1 may be included in the accumulated data DATA_AC (or drive time data), and the accumulated data DATA_AC is stored and updated in the memory 620 described later.

[0146] Similarly, the accumulator 610 may calculate the second driving time for the second pixel, thereby updating the second accumulated gray value GRAY_AC2 , and the second accumulated gray value GRAY_AC2 may be included in the accumulated data DATA_AC and stored and updated in the memory 620 .

[0147] The memory 620 may store the accumulated data DATA_AC and provide the accumulated data DATA_AC to the accumulator 610 in response to a request of the accumulator 610 (ie, a request to provide the accumulated data DATA_AC), and may update the accumulated data DATA_AC in real time or periodically.

[0148] In addition, the memory 620 may store degradation coefficients or corresponding lookup tables LUT1 to LUT2. As shown in Table 1 below, the first lookup table LUT1 may include first degradation coefficients according to normal pixels (eg, referring to Figure 6 The first degradation curve CURVE1 described above is used to represent the grayscale value or degradation compensation ratio compensated for each driving time for a normal pixel.

[0149] [Table 1]

[0150]

[0151] Table 1 shows an example of the first lookup table LUT1.

[0152] According to an embodiment, the first lookup table LUT1 may include compensated gray values ​​GRAY1_L1 ′, GRAY1_L″ according to driving times t1 , t2 corresponding to the first input gray value GRAY1_L1 .

[0153] According to an embodiment, the first lookup table LUT1 may also include grayscale compensation values ​​GRAY1_D1, GRAY1_D2 (or compensated grayscale values) instead of the compensated grayscale values ​​GRAY1_L1′, GRAY1_L″. Here, the grayscale compensation values ​​GRAY1_D1, GRAY1_D2 may be the difference between the compensated grayscale values ​​GRAY1_L1′, GRAY1_L1″ according to the driving times t1, t2 and the first input grayscale value GRAY1_L1.

[0154] Similarly, the second lookup table LUT2 may include a second degradation coefficient according to the defective pixel (eg, referring to Figure 6 The second degradation curve CURVE2 (illustrated in FIG. 2 ) shows the compensated grayscale value or degradation compensation ratio corresponding to the driving time of the defective pixel. Based on the second degradation coefficient of the defective pixel (i.e., the second degradation curve CURVE2), the compensated grayscale value of the defective pixel can be greater than the compensated grayscale value of a normal pixel based on the same driving time.

[0155] In addition, the degradation coefficients or the corresponding lookup tables LUT1-LUT2 are described as being stored in the memory 620, but the present invention is not limited thereto. For example, the degradation coefficients or the corresponding lookup tables LUT1-LUT2 may be stored in the storage unit 500 and loaded from the storage unit 500 into the memory 620 when the display device is powered on.

[0156] The memory 620 may be implemented by a volatile memory device such as a dynamic random access memory (DRAM) or a static random access memory (SRAM).

[0157] The memory 620 may provide the compensator 630 with the lookup tables LUT1 and LUT2 in response to a request from the compensator 630. In addition, the memory 620 may provide the compensator 630 with the accumulated data DATA_AC in response to a request from the compensator 630.

[0158] The compensator 630 may compensate the image data DATA1 based on the accumulated data DATA_AC and the lookup tables LUT1 , LUT2 (or degradation coefficients), thereby generating compensated data DATA2 .

[0159] For example, the compensator 630 may compensate the first grayscale value GRAY1 (i.e., the grayscale value for a normal pixel) based on the first accumulated grayscale value GRAY_AC1 and the first lookup table LUT1 (or the first degradation coefficient), thereby calculating a first compensated grayscale value GRAY1′. Similarly, the compensator 630 may compensate the second grayscale value GRAY2 (i.e., the grayscale value for a defective pixel) based on the second accumulated grayscale value GRAY_AC2 and the second lookup table LUT2 (or the second degradation coefficient), thereby calculating a second compensated grayscale value GRAY2′.

[0160] In an embodiment, the compensator 630 may include a selection section 631 and a calculation section 632 .

[0161] The selection part 631 (or selector) may generate compensation data DATA_C corresponding to the image data DATA1 based on the accumulated data DATA_AC and the lookup tables LUT1 , LUT2 (or degradation coefficients).

[0162] For example, the selection unit 631 may select the second lookup table LUT2 (or the second degradation coefficient) based on the position information of the defective pixel, and may obtain the second grayscale compensation value based on the second grayscale value GRAY2, the second driving time (or the second cumulative grayscale value GRAY_AC2), and the second lookup table LUT2 (or the second degradation coefficient). In addition, the selection unit 631 may select the first lookup table LUT1 (or the first degradation coefficient) for a normal pixel without separate position information, and may obtain the first grayscale compensation value based on the first grayscale value GRAY1, the first driving time (or the first cumulative grayscale value GRAY_AC1), and the first lookup table LUT1 (or the first degradation coefficient). That is, the selection unit 631 may select the second lookup table LUT2 (or the second degradation coefficient) based on the position information of the defective pixel (for example, Figure 7 or Figure 8One of the lookup tables LUT1 and LUT2 (or degradation coefficients) is selected based on the information in the lookup table LUT.

[0163] The calculation unit 632 (or calculator) can generate compensated data DATA2 by adding the compensation data DATA_C to the image data DATA1. For example, the calculation unit 632 can calculate a first compensated gray value GRAY1' by adding the first gray compensation value to the first gray value GRAY1, and can calculate a second compensated gray value GRAY2' by adding the second gray compensation value to the second gray value GRAY2.

[0164] As described above, the compensation part 600 may compensate for the first gray value GRAY1 for the normal pixel using the first lookup table LUT1 and may compensate for the second gray value GRAY2 for the defective pixel using the second lookup table LUT2.

[0165] Figure 10 It is shown that the Figure 1 A circuit diagram of another embodiment of a pixel in a display device.

[0166] Combine Figure 1 、 Figure 2 as well as Figure 9 And refer to Figure 10 , the pixel PX_1 may include a light emitting unit EMU_1 and a pixel circuit PXC. Since the pixel circuit PXC has been referred to Figure 2 The above description has been given, so the repeated description will not be repeated.

[0167] The light-emitting unit EMU_1 may include a third stage SET3 (or a third sub-light-emitting unit, or a third element group), a first stage SET1_1, a second stage SET2_1, and a fourth stage SET4 (or a fourth sub-light-emitting unit, or a fourth element group), which are sequentially connected between a first power line PL1 and a second power line PL2. The light-emitting unit EMU_1 may include first to eighth electrodes EL1_1 to EL8. Each of the first to fourth stages SET1_1 to SET4 may include a plurality of light-emitting elements LD connected in parallel along the same direction between two electrodes among the first to eighth electrodes EL1_1 to EL8.

[0168] The first level SET1_1 and the second level SET2_1 can be respectively Figure 2 The illustrated first stage SET1 and second stage SET2 are substantially the same or similar.

[0169] The first stage SET1_1 may include a first electrode EL1_1 (or the first-second intermediate electrode CTE1-2) and a second electrode EL2_1 (or the second-first intermediate electrode CTE2-1), and may include at least one first light emitting element LD1 connected between the first electrode EL1_1 (or the first-second intermediate electrode CTE2-1) and the second electrode EL2_1 (or the second-first intermediate electrode CTE2-1).

[0170] The second stage SET2_1 may include a fourth electrode EL4_1 (or a second-2 intermediate electrode CTE2-2) and a third electrode EL3_1 (or a third-1 intermediate electrode CTE3-1), and may include at least one second light emitting element LD2 connected between the fourth electrode EL4_1 (or the second-2 intermediate electrode CTE2-2) and the third electrode EL3_1 (or the third-1 intermediate electrode CTE3-1).

[0171] The third stage SET3 may include fifth and sixth electrodes EL5 and EL6 (or first intermediate electrode CTE1 - 1 ), and may include at least one third light emitting element LD3 connected between the fifth and sixth electrodes EL5 and EL6 (or first intermediate electrode CTE1 - 1 ).

[0172] The fourth stage SET4 may include an eighth electrode EL8 (or the third-second intermediate electrode CTE3 - 2 ) and a seventh electrode EL7 , and may include at least one fourth light emitting element LD4 connected between the eighth electrode EL8 (or the third-second intermediate electrode CTE3 - 2 ) and the seventh electrode EL7 .

[0173] The first first intermediate electrode CTE1-1 and the first second intermediate electrode CTE1-2 may constitute the first intermediate electrode CTE1. Similarly, the second first intermediate electrode CTE2-1 and the second second intermediate electrode CTE2-2 may constitute the second intermediate electrode CTE2. The third first intermediate electrode CTE3-1 and the third second intermediate electrode CTE3-2 may constitute the third intermediate electrode CTE3.

[0174] In the above embodiment, the fifth electrode EL5 may be an anode electrode of the light emitting unit EMU_1 of the pixel PX_1 , and the seventh electrode EL7 may be a cathode electrode of the light emitting unit EMU_1 .

[0175] In addition, when the pixel PX_1 includes four levels SET1_1 to SET4, the defective pixels can be divided into three types. For example, the defective pixels can be divided into a first defective pixel including one defective level, a second defective pixel including two defective levels, and a third defective pixel including three defective levels. In this case, as shown in FIG. Figure 8As described above, the storage unit 500 (or the lookup table LUT) can store (or include) the position information of the defective pixel and the number information of the defect level of the defective pixel. Figure 5 and Figure 6 In an illustrative manner, a degradation curve of each of the first to third defective pixels can be obtained through experiments, and a degradation coefficient of each of the first to third defective pixels (or a lookup table including the compensation grayscale value corresponding thereto) can be obtained from the degradation curve, and the degradation coefficient of each of the first to third defective pixels can be stored in the storage unit 500. In this case, the compensation unit 600 (refer to Figure 1 ) can compensate the grayscale values ​​of the first to third defective pixels based on different degradation coefficients (e.g., second, third, and fourth degradation coefficients that are different from each other). For example, the compensation unit 600 can compensate the grayscale value of the first defective pixel based on the second degradation coefficient, the grayscale value of the second defective pixel based on the third degradation coefficient, and the grayscale value of the third defective pixel based on the fourth degradation coefficient.

[0176] Figure 11 is a flowchart illustrating a method for driving a display device according to an embodiment. Figure 11 The method can be Figure 1 The display device is executed as an object. Figure 2 and Figure 10 As described above, the pixel PX or PX_1 may include stages SET1 ˜ SET2 or SET1_1 ˜ SET4 connected in series, and each of the stages SET1 ˜ SET2 or SET1_1 ˜ SET4 may include a light emitting element.

[0177] Reference Figure 1 、 Figure 5 as well as Figure 11 ,exist Figure 11 In the method, a defective pixel can be detected by applying a driving voltage to the display device (or display unit 100) (S110). Here, the defective pixel may include a short-circuited portion or a portion whose short-circuited portion has been repaired in at least one stage.

[0178] As reference Figure 5 As mentioned, Figure 11 In the method, a thermal infrared image can be obtained by photographing the display device using the inspection device 50, a defect level can be detected from the thermal infrared image, and position information of the defective pixel can be obtained based on the defect level.

[0179] In one embodiment, when a pixel includes only two levels (e.g. Figure 2 Pixel PX), Figure 11The method can only obtain the position information of the defective pixel, but not the position information of the normal pixel and the number information of the defect level. In this case, the capacity of the storage unit 500 can be reduced.

[0180] In another embodiment, in the case where a pixel includes more than three levels (e.g. Figure 10 Under the pixel PX_1), Figure 11 In addition to the position information of the defective pixel, the method can also obtain the number of defect levels. For example, the position information of the first defective pixel and the number of defect levels (e.g., one) and the position information of the second defective pixel and the number of defect levels (e.g., two) can be obtained.

[0181] Then, in Figure 11 In the method, a first degradation coefficient of a normal pixel and a second degradation coefficient of a defective pixel may be obtained by driving the display device at a reference time (S120). Figure 11 In the method, the display device can be driven at a reference time and the brightness of the display device can be periodically measured by the inspection device 50, and the brightness can be obtained based on the measured brightness. Figure 6 The first degradation curve CURVE1 and the second degradation curve CURVE2. Figure 11 In the method, it can be based on Figure 6 The first degradation coefficient can be obtained by using the first degradation curve CURVE1 and Mathematical Formula 1, and can be based on Figure 6 The second degradation coefficient is obtained by using the second degradation curve CURVE2 and Mathematical Formula 1.

[0182] In one embodiment, each of the first degradation coefficient and the second degradation coefficient may include a grayscale coefficient, a temperature coefficient, a frequency coefficient, and a luminous duty cycle coefficient, respectively representing the change in the brightness according to the grayscale value, driving temperature, driving frequency, and the luminous duty cycle of the pixel.

[0183] For example, in Figure 11 In the method, the grayscale coefficient can be obtained by measuring the brightness of the display unit 100 or performing an experiment by the inspection device 50 while changing the grayscale value of the pixel or setting the grayscale value of each pixel differently. Figure 11 In the method, the temperature coefficient can be obtained by performing an experiment while changing the driving temperature of the display device or setting the driving temperature of each display device differently. Figure 11 In the method, the frequency coefficient can be obtained by performing experiments while changing the driving frequency of the display device or setting the driving frequency of each display device differently. Figure 11In the method, an experiment can be performed while changing the light emission duty ratio of the pixel or setting the light emission duty ratio of each pixel differently, thereby obtaining a light emission duty ratio coefficient.

[0184] exist Figure 11 In the method, the position information of the defective pixel and the first degradation coefficient and the second degradation coefficient may be stored in the storage unit 500 of the display device (S130). Figure 8 As described above, the position information of the defective pixel can be stored in the storage unit 500 in the form of a lookup table LUT. In the case of additionally obtaining information on the number of defect levels of the defective pixel, the information on the number of defect levels can also be stored in the storage unit 500 together with the position information of the corresponding defective pixel. In addition, instead of the first degradation coefficient and the second degradation coefficient, the lookup tables LUT1 and LUT2 corresponding to the first degradation coefficient and the second degradation coefficient (see Figure 9 ) can also be stored in the storage unit 500.

[0185] exist Figure 11 In the method, the grayscale value of the normal pixel can be compensated based on the first degradation coefficient, and the grayscale value of the defective pixel can be compensated based on the second degradation coefficient different from the first degradation coefficient (S210), and the compensated data DATA2 can be generated (refer to Figure 1 ).

[0186] According to an embodiment, in the case where a plurality of degradation coefficients are preset to correspond to the number of defect levels, for example, in the case where a second degradation coefficient for a first defective pixel including one defect level, a third degradation coefficient for a second defective pixel including two defect levels, etc. is set, Figure 11 In the method, the grayscale value of the first defective pixel may be compensated by using the second degradation coefficient, and the grayscale value of the second defective pixel may be compensated by using a third degradation coefficient different from the second degradation coefficient.

[0187] exist Figure 11 In the method, a data signal (or data voltage) may be generated based on the compensated data DATA2 and provided to the pixel (S220). Figure 1 As mentioned, Figure 11 In the method, the data driving unit 300 may be used to generate the data signal.

[0188] The above description is made with reference to the preferred embodiments of the present invention. However, any skilled technician in the technical field to which the present invention belongs or any person with ordinary knowledge in the technical field to which the present invention belongs will understand that the present invention can be modified and changed in various ways without departing from the scope of the idea and technical field of the present invention recorded in the claims.

[0189] Therefore, the technical scope of the present invention should be determined by the claims and is not limited to the contents described in the detailed description of the specification.

Claims

1. A display device, characterized in that: include: A display panel including pixels, each of the pixels including stages connected in series with each other, each of the stages including a light emitting element; a storage unit configured to store position information of a defective pixel among the pixels when a defect exists in the level; a compensation unit that compensates grayscale values ​​in image data of normal pixels among the pixels based on a first degradation coefficient, and compensates grayscale values ​​of the defective pixels corresponding to the position information based on a second degradation coefficient different from the first degradation coefficient, thereby generating compensated data; as well as The data driving unit generates a data voltage based on the compensated data and provides the data voltage to the pixel.

2. The display device according to claim 1, wherein The pixels of the display panel are connected to the data line, the first scan line, the second scan line and the sensing line. The data driving section is configured to sense light emission characteristics of the pixel through the sensing line during a sensing period.

3. The display device according to claim 2, wherein: Also includes: a timing control unit that receives a control signal and an image signal from the outside and provides the compensation unit with image data for rearranging the image signal to match the arrangement of the pixels; as well as A scan driving unit is provided on the display panel and supplies a first scan signal and a second scan signal to the first scan line and the second scan line respectively. The timing control unit is configured to generate a data control signal and a scan control signal corresponding to the received control signal, and provide the data control signal to the data driving unit and the scan control signal to the scan driving unit.

4. The display device according to claim 1, wherein Each of the pixels further comprises an identical pixel circuit that provides a drive current to the stage, said pixels include the same number of said stages as one another, The light emitting elements of the pixels have the same size as each other and emit light in the same color.

5. The display device according to claim 1, wherein One of the stages of the defective pixels includes a short-circuit defect portion or a portion where the short-circuit defect is repaired, At least a portion of the light emitting elements in the one stage does not emit light, and the light emitting elements in the remaining stages of the stages emit light.

6. The display device according to claim 1, wherein Each of said pixels comprises two of said stages, The storage section does not include position information of the normal pixels and number information of defect levels.

7. The display device according to claim 1, wherein Each of said pixels comprises three or more said stages, The defective pixel includes a first defective pixel and a second defective pixel, the first defective pixel includes one defective level having the defect, and the second defective pixel includes two defective levels having the defect, The storage unit stores position information and quantity information of the defect levels of each of the first defective pixel and the second defective pixel, and the compensation unit compensates the grayscale value of the first defective pixel based on the second degradation coefficient, and compensates the grayscale value of the second defective pixel based on a third degradation coefficient different from the first degradation coefficient and the second degradation coefficient.

8. The display device according to claim 1, wherein The compensation unit includes: an accumulation circuit for calculating a driving time by accumulating grayscale values ​​in the compensated data; a memory device storing the driving time; and A compensation circuit calculates a compensation value for each of the pixels based on the driving time and the first and second degradation coefficients, and compensates for grayscale values ​​within the image data using the compensation value.

9. The display device according to claim 2, wherein: Each of the pixels comprises: a first transistor electrically connected between the first power line and the second power line; a second transistor electrically connected between the data line and the gate electrode of the first transistor; a third transistor electrically connected between an electrode of the first transistor and the sensing line; and a storage capacitor electrically connected between the gate electrode and the first electrode of the first transistor, The stage is electrically connected between an electrode of the first transistor and the second power line.

10. The display device according to claim 9, wherein: One electrode of the second transistor is connected to the gate electrode of the first transistor, and the gate electrode of the second transistor is connected to the first scan line. An electrode of the third transistor is connected to the one electrode of the first transistor, and a gate electrode of the third transistor is connected to the second scan line.

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