Display device

Abstract

To provide a display device with which burn-in of a self-luminous element is suppressed.SOLUTION: A display device comprises: a display panel in which a plurality of pixels including self-luminous elements are arranged; a drive circuit for supplying a drive current to each of the plurality of pixels; and a control unit for controlling the drive circuit so that the drive current corresponding to a video signal is supplied to each of the plurality of pixels. The control unit determines the presence of a pixel among the plurality of pixels whose degradation information that indicates the degree of degradation of light emission efficiency has increased to a prescribed value or greater, and when determining that there exists a pixel whose degradation information has increased to the prescribed value or greater, controls the drive circuit so that the drive current supplied to the pixel becomes smaller than that before the degradation information increases to the prescribed value or greater.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a display device. [Background technology]

[0002] Patent Document 1 discloses a lighting device that compensates for deterioration of an electroluminescence (EL) element by increasing a voltage supplied to the EL element in accordance with the accumulated lighting time of the EL element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-245033 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to the lighting device of Patent Document 1, the voltage supplied to the EL element is increased according to the accumulated lighting time of the EL element, so that the longer the accumulated lighting time of the EL element, the more likely the burn-in of the EL element occurs. An object of one aspect of the present disclosure is to provide a display device that suppresses the burn-in of the self-luminous elements. [Means for solving the problem]

[0005] A display device according to one embodiment of the present disclosure comprises a display panel having a plurality of pixels, each including a light-emitting element; a drive circuit for supplying a drive current to each of the plurality of pixels; and a control unit for controlling the drive circuit so that the drive current corresponding to a video signal is supplied to each of the plurality of pixels, wherein the control unit determines whether or not there is a pixel among the plurality of pixels for which degradation information indicating a degree of degradation of luminous efficiency has reached a predetermined value or greater, and when it determines that there is a pixel for which the degradation information has reached the predetermined value or greater, controls the drive circuit so that the drive current supplied to the pixel is smaller than before the degradation information reached the predetermined value or greater. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a display device according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating a schematic configuration of a pixel circuit included in each of a plurality of pixels according to an embodiment. [Diagram 3] FIG. 3 is a diagram showing the relationship between elapsed time and degradation information of a pixel in the display device according to the embodiment. [Figure 4] FIG. 4 is a diagram showing the relationship between elapsed time and driving current of a pixel in the display device according to the embodiment. [Diagram 5] FIG. 5 is a diagram showing a flow of processing by the control unit in the display device according to the embodiment. [Figure 6] FIG. 6 is a diagram illustrating the relationship between elapsed time and degradation information of a pixel PX in a display device according to a first modification of the embodiment. [Figure 7] FIG. 7 is a diagram illustrating the relationship between elapsed time and driving current of a pixel in a display device according to the first modification of the embodiment. [Figure 8] FIG. 8 is a diagram illustrating a process flow of a control unit in a display device according to the second modification of the embodiment. [Figure 9] FIG. 9 is a diagram illustrating a schematic configuration of a display device according to a third modification of the embodiment. [Figure 10] 13 is a diagram illustrating a relationship between elapsed time and degradation information of a pixel in a display device according to a third modified example of an embodiment. FIG. [Figure 11] FIG. 11 is a diagram illustrating the relationship between the elapsed time and the driving current of a pixel in a display device according to the third modification of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] [Embodiment] 1 is a diagram illustrating a schematic configuration of a display device 1 according to an embodiment. The display device 1 includes a display panel 10, a source driver (drive circuit) 30, a control unit 40, and a storage unit 50. The display panel 10 includes a plurality of pixels PX, a gate driver 13, a plurality of gate lines G, and a plurality of data lines S. For example, the control unit 40 includes a degradation information determination unit 41 and a display control unit 42.

[0008] The pixels PX are arranged in a matrix in an image display area 11 of the display panel 10. Each of the pixels PX includes a self-emitting light-emitting element. In each of the pixels PX, as described later with reference to FIG. 2 etc., a driving current is supplied to the light-emitting element, causing the light-emitting element to emit light.

[0009] The display panel 10 displays an image in the display area 11 by, for example, the spontaneous emission of light from a plurality of pixels PX. As the display panel 10, for example, an organic EL (electro-luminescence) display panel using OLEDs (organic light emitting diodes) as light emitting elements, or a QLED display panel using QLEDs (quantum dot light emitting diodes) as light emitting elements, can be used. Note that the display panel 10 may be any display panel that includes a light emitting element for each of the plurality of pixels PX, and is not limited to an organic EL display panel or a QLED display panel.

[0010] The gate lines G and the data lines S are arranged to extend so as to intersect with each other within the display area 11. Each of the pixels PX is arranged at a portion where the data lines S and the gate lines G intersect with each other.

[0011] One end of each of the gate lines G is connected to the gate driver 13. The gate driver 13 sequentially scans each of the gate lines G based on a gate control signal output from the control unit 40. That is, the gate driver 13 outputs a scanning signal for selecting the pixels PX row by row to each of the pixels PX via each of the gate lines G.

[0012] One end of each of the multiple data lines S is connected to the source driver 30. The source driver 30 drives each of the multiple pixels PX via the multiple data lines S based on a source control signal output from the control unit 40. As will be described later with reference to FIG. 2, the source driver 30 is a drive circuit for supplying a drive current to each of the multiple pixels PX.

[0013] For example, when the source driver 30 receives from the control unit 40 a gradation signal (digital signal) corresponding to the luminance value at which the pixel PX is to emit light, the source driver 30 converts the received digital signal into an analog signal to generate a gradation voltage and supplies the analog signal to the data line S. As a result, a drive current corresponding to the luminance value at which the pixel PX is to emit light based on the video signal flows through the pixel PX connected to the data line S.

[0014] The control unit 40 controls the operation of the gate driver 13 and the source driver 30 to display an image in the display area 11. The control unit 40 controls the source driver 30 and the gate driver 13 so that a drive current corresponding to a video signal input from outside the control unit 40 is supplied to each of the plurality of pixels PX. For example, the control unit 40 corrects the video signal input from outside the control unit 40, generates a gradation signal, which is a digital signal, corresponding to the luminance value at which each of the plurality of pixels PX should emit light, and outputs the generated gradation signal to the source driver 30.

[0015] The degradation information determination unit 41 generates degradation information indicating the degree of degradation of the luminous efficiency of each of the multiple pixels PX based on the video signal input to the control unit 40, and stores the generated degradation information in the memory unit 50 as degradation information accumulation data 51.

[0016] The deterioration information is a time-integrated value of the power consumption supplied to each of the plurality of pixels PX. The power consumption [mW] supplied to each of the plurality of pixels PX is expressed as the product of the gradation voltage [mV] supplied to each pixel PX based on the video signal and the drive current [mA] flowing through each pixel PX when the gradation voltage is supplied. The deterioration information determination unit 41 obtains the power consumption [mW] supplied to each of the plurality of pixels PX and the time [h] during which the power consumption is supplied based on the input video signal, thereby obtaining deterioration information [mWh] for each of the plurality of pixels PX. Then, the deterioration information determination unit 41 accumulates and stores the obtained deterioration information for each of the plurality of pixels PX in the storage unit 50 as deterioration information accumulation data 51.

[0017] 3 and the like, the degradation information determination unit 41 determines whether or not there is a pixel PX whose degradation information indicating the degree of degradation of the luminous efficiency has reached a predetermined value or more among the multiple pixels PX. Then, when the degradation information determination unit 41 determines that there is a pixel PX whose degradation information has reached a predetermined value or more, the display control unit 42 controls the driving of the source driver 30 so that the drive current supplied to the pixel PX whose degradation information has reached a predetermined value or more is smaller than that before the degradation information reached the predetermined value or more.

[0018] The deterioration information determination unit 41 and the display control unit 42 included in the control unit 40 may be realized by a logic circuit (hardware) formed by an integrated circuit (IC chip) or the like, or may be realized by software. In the latter case, the deterioration information determination unit 41 and the display control unit 42 included in the control unit 40 can be realized by the control unit 40, which can be realized by a CPU or the like, reading out a program stored in the storage unit 50 into a memory or the like (not shown) and executing it.

[0019] As described above, the storage unit 50 stores degradation information accumulation data 51 in which degradation information indicating the degree of degradation of the luminous efficiency of each of the multiple pixels PX is accumulated. For example, a flash memory or the like can be used as the storage unit 50. Note that the storage unit 50 is not limited to a flash memory, and may be a semiconductor memory such as a static random access memory (SRAM), a dynamic random access memory (DRAM), a read only memory (ROM), or a solid state drive (SSD), a register, a magnetic storage device such as a hard disk drive (HDD), or an optical storage device such as an optical disk drive.

[0020] 2 is a diagram showing a schematic configuration of a pixel circuit 20 included in each of the pixels PX. The pixel circuit 20 includes a light emitting element 21, a capacitor C1, a selection transistor Tr1, and a drive transistor Tr2.

[0021] The light-emitting element 21 is a self-emitting element such as an OLED (Organic Light Emitting Diode) or a QLED (Quantum dot Light Emitting Diode). Note that the light-emitting element 21 is not limited to an OLED or a QLED.

[0022] The capacitor C1 has one terminal connected to the high-level power supply line ELVDD and the drain terminal of the drive transistor Tr2, and the other terminal connected to the drain terminal of the selection transistor Tr1 and the gate terminal of the drive transistor Tr2.

[0023] The selection transistor Tr1 is provided between the data line S and the gate terminals of the capacitor C1 and the drive transistor Tr2. The selection transistor Tr1 has a gate terminal connected to the gate line G1, a source terminal connected to the data line S, and a drain terminal connected to the gate terminal of the drive transistor Tr2 and the other terminal of the capacitor C1.

[0024] The driving transistor Tr2 is connected in series with the light-emitting element 21. In the driving transistor Tr2, a gate terminal is connected to the drain terminal of the selection transistor Tr1 and the other terminal of the capacitor C1, a drain terminal is connected to the high-level power supply line ELVDD and one terminal of the capacitor, and a source terminal is connected to the anode of the light-emitting element 21.

[0025] Next, the operation of the pixel circuit 20 will be described with reference to Fig. 2. During an image display period, i.e., a period during which a gradation voltage is written, the gate line G is set to an active state (selected state) by the gate driver 13, and the selection transistor Tr1 is turned on.

[0026] Then, in response to the grayscale signal supplied to the source driver 30 by the control unit 40, a grayscale voltage is supplied from the source driver 30 to the data line S. As a result, a charge corresponding to the supplied grayscale voltage is stored in the capacitor C1. Then, the gate line G is put into an inactive state (non-selected state) by the gate driver 13, so that the selection transistor Tr1 is turned off. Then, the drive transistor Tr2 is turned on, and a drive current 61 flows between the drain terminal and source terminal of the drive transistor Tr2 and further between the anode and cathode of the light-emitting element 21 in response to the charge stored in the capacitor C1. As a result, the light-emitting element 21 emits light at a target luminance.

[0027] Fig. 3 is a diagram showing the relationship between elapsed time and degradation information of the pixel PX in the display device 1 according to the embodiment. Fig. 4 is a diagram showing the relationship between elapsed time and drive current of the pixel PX in the display device 1 according to the embodiment.

[0028] Here, in a self-luminous display device that displays an image by emitting light from the light-emitting elements of a plurality of pixels, a pixel that is supplied with a high grayscale voltage for a long time and through which a large driving current flows is likely to have its luminous efficiency deteriorated. When the luminous efficiency of a plurality of pixels deteriorates, so-called burn-in may occur. In a display device in which pixel burn-in occurs, a portion of a displayed image that includes a pixel in which burn-in occurs may discolor or a part of an image displayed in a previous frame period may not disappear, causing a decrease in the display quality of the image. Therefore, in the display device 1 according to this embodiment, image display control is performed to suppress the occurrence of burn-in in the pixel PX. A specific description will be given below.

[0029] In Fig. 3, data M1 shown by a solid line represents the change in degradation information of a pixel PX whose degradation information increases at a relatively fast rate among the multiple pixels PX. In Fig. 3, data M2 shown by a dashed line represents the change in degradation information of a pixel PX whose degradation information increases at a relatively slow rate among the multiple pixels PX. In this way, the rate at which degradation information increases differs depending on the pixel PX.

[0030] In Fig. 4, data N1 shown by a solid line represents the change in the drive current of a pixel PX whose degradation information increases at a relatively fast rate among the multiple pixels PX. In Fig. 4, data N2 shown by a dashed line represents the change in the drive current of a pixel PX whose degradation information increases at a relatively slow rate among the multiple pixels PX.

[0031] For example, a predetermined value Ath is set in advance as a threshold value of degradation information for determining that the degradation of the luminous efficiency of the pixel PX is progressing. An example of the predetermined value Ath is, for example, 40000 [mWh]. Note that the predetermined value Ath is not limited to 40000 [mWh] and can be set arbitrarily.

[0032] Then, for example, as shown in the data M1 of FIG. 3, among a plurality of pixels PX, it is assumed that the degradation information of the pixel PX with a relatively fast rising rate of the degradation information reaches a predetermined value Ath at time T2. Then, the degradation information determination unit 41 determines that there is a pixel PX among the plurality of pixels PX whose degradation information reaches the predetermined value Ath at time T2, and identifies the pixel PX whose degradation information reaches the predetermined value Ath. In the example shown in the data M1 of FIG. 3, the degradation information rises from time T1 to time T2, and the degradation information reaches the predetermined value Ath at time T2.

[0033] Then, as shown in the data N1 of FIG. 4, the display control unit 42 generates a gradation signal so that the drive current flowing in accordance with the video signal in the pixel PX specified by the degradation information determination unit 41 as having reached the predetermined value Ath becomes less after time T2 than before time T2, and supplies it to the source driver 30. For example, the display control unit 42 may be set with a predetermined ratio for reducing the drive current that flows in advance, such as making the drive current flowing in the pixel PX whose degradation information has reached the predetermined value Ath decrease by a predetermined ratio of the drive current flowing before time T2 after time T2. In the example shown in FIG. 4, the display control unit 42 shows an example of reducing the drive current flowing in the pixel PX whose degradation information has reached the predetermined value Ath from the current value B3 to the current value B1 at time T2. Note that the display control unit 42 may reduce the drive current from the current value B3 to the current value B1 over a predetermined period from time T2.

[0034] As a result, the drive current flowing in accordance with the video signal in the pixel PX whose degradation information has reached the predetermined value Ath becomes smaller after time T2 than before time T2. In the example shown in the data N1 of FIG. 4, the drive current flowing in the pixel PX whose degradation information has reached the predetermined value Ath decreases from the current value B3 between time T1 and time T2 to the current value B1 (B1 < B3) until time T3 after time T2.

[0035] 3, the rate of increase in the degradation information of the pixel PX whose degradation information has reached the predetermined value Ath is smaller after time T2, such as from the predetermined value Ath at time T2 to value A2 at time T3, than the rate of increase from time T1 to time T2 before time T2. This makes it possible to suppress the rate of increase in the degradation information of the pixel PX whose degradation information increases relatively quickly after time T2, compared to before time T2. In other words, it is possible to slow down the rate of deterioration of the luminous efficiency of the pixel PX whose degradation information increases relatively quickly after time T2, compared to before time T2.

[0036] On the other hand, for example, as shown in data M2 of Fig. 3, the degradation information of a pixel PX whose degradation information increases at a relatively slow rate among the multiple pixels PX is a value A1 smaller than the predetermined value Ath at time T2, and reaches the predetermined value Ath at time T3 after time T2. Then, the degradation information determination unit 41 determines that there is a pixel PX whose degradation information reaches the predetermined value Ath at time T3 among the multiple pixels PX, and identifies the pixel PX whose degradation information has reached the predetermined value Ath. In the example shown in data M2 of Fig. 3, the degradation information increases from time T1 to time T3, and the degradation information reaches the predetermined value Ath at time T3.

[0037] Then, as shown in data N2 of FIG. 4, the display control unit 42 generates a gradation signal so that the driving current flowing in the pixel PX specified by the degradation information determination unit 41 as having the degradation information reach the predetermined value Ath in response to the video signal is reduced from time T3 onward compared to before time T3, and supplies the gradation signal to the source driver 30. For example, the display control unit 42 may set a predetermined rate for reducing the driving current flowing in advance, such as reducing the driving current flowing in response to the video signal in the pixel PX in which the degradation information has reached the predetermined value Ath by a predetermined rate from before time T3 onward. In the example shown in FIG. 4, the display control unit 42 reduces the driving current flowing in the pixel PX in which the degradation information has reached the predetermined value Ath from a current value B2 to a current value B1 at time T3. Note that the display control unit 42 may reduce the driving current flowing in the pixel PX in which the degradation information has reached the predetermined value Ath from a current value B2 to a current value B1 over a certain period from time T3.

[0038] As a result, the drive current flowing in response to the video signal to the pixel PX whose degradation information has reached the predetermined value Ath becomes smaller after time T3 than before time T3. In the example shown in data N2 in Fig. 4, the drive current flowing in response to the video signal to the pixel PX whose degradation information has reached the predetermined value Ath is reduced from the current value B2 between time T1 and time T3.

[0039] 3, the rate of increase in the degradation information of the pixel PX whose degradation information has reached the predetermined value Ath becomes slower after time T3 than the rate of increase from time T1 to time T3 before time T3. As a result, after time T3, it is possible to suppress the rate of increase in the degradation information of the pixel PX whose rate of increase in the degradation information is relatively slower than that before time T3.

[0040] In addition, the driving current flowing through the pixel PX whose degradation information has reached the predetermined value Ath is made smaller than that before the degradation information reached the predetermined value Ath, so that the difference in degradation information between each of the pixels PX can be suppressed. Specifically, for example, the difference between the predetermined value Ath, which is the value of the degradation information of the pixel PX shown in the data M1 at time T2 in Fig. 3, and the predetermined value Ath, which is the value of the degradation information of the pixel PX shown in the data M2, is smaller than the difference between the predetermined value Ath, which is the value of the degradation information of the pixel PX shown in the data M1 at time T2 in Fig. 3, and the value A1 of the degradation information of the pixel PX shown in the data M2.

[0041] 5 is a diagram showing a process flow of the control unit 40 in the display device 1 according to the embodiment. In step S1, the degradation information determination unit 41 generates degradation information for each of the plurality of pixels PX based on the video signal acquired by the control unit 40, and accumulates the generated degradation information for each of the plurality of pixels PX in the storage unit 50 as degradation information accumulation data 51.

[0042] Next, in step S2, the degradation information determination unit 41 refers to the degradation information accumulation data 51 stored in the memory unit 50 and determines whether or not there is a pixel PX whose accumulated degradation information is equal to or greater than a predetermined value Ath among the multiple pixels PX. In step S2, if the degradation information determination unit 41 determines that there is no pixel PX whose accumulated degradation information is equal to or greater than a predetermined value Ath among the multiple pixels PX (No in step S2), the process returns to step S1.

[0043] Furthermore, in step S2, if the deterioration information determination unit 41 determines that there is a pixel PX among the multiple pixels PX whose accumulated deterioration information has become equal to or greater than a predetermined value Ath (if Yes in step S2), then in step S3, the display control unit 42 reduces the drive current supplied to the pixel PX among the multiple pixels PX for which the deterioration information determination unit 41 has determined that the accumulated deterioration information has become equal to or greater than the predetermined value Ath, compared to the drive current supplied before the deterioration information became equal to or greater than the predetermined value Ath.

[0044] 5 shows an example of the process flow of the control unit 40, in which the display control unit 42 sequentially reduces the drive current of the pixels PX whose degradation information has become equal to or greater than the predetermined value Ath, compared to the drive current supplied before the degradation information became equal to or greater than the predetermined value Ath. In this way, by sequentially reducing the drive current of the pixels PX whose degradation information has become equal to or greater than the predetermined value Ath, it is possible to quickly suppress burn-in of the light-emitting element 21 of the pixel PX whose degradation information has become equal to or greater than the predetermined value Ath.

[0045] As described above, in the display device 1 according to the present embodiment, the degradation information determination unit 41 determines whether or not there is a pixel PX whose degradation information indicating the degree of degradation of the luminous efficiency has reached a predetermined value Ath or more among the multiple pixels PX. Then, when the degradation information determination unit 41 determines that there is a pixel PX whose degradation information has reached the predetermined value Ath or more, the display control unit 42 controls the source driver 30 so that the drive current supplied to the pixel PX whose degradation information has reached the predetermined value Ath or more becomes smaller than that before the degradation information reached the predetermined value Ath or more.

[0046] In other words, for example, the display control unit 42 reduces the value representing the luminance value indicated by the gradation signal supplied to the source driver 30 so that the drive current supplied to the pixel PX whose degradation information has become equal to or greater than a predetermined value Ath is smaller than that before the degradation information became equal to or greater than the predetermined value Ath.

[0047] This makes it possible to prevent the deterioration of the pixels PX whose deterioration information is equal to or greater than the predetermined value Ath from progressing and causing burn-in. This makes it possible to provide a display device 1 that prevents burn-in of the light-emitting elements 21.

[0048] In addition, as described with reference to FIG. 3, the variation in the deterioration degree between the pixels PX can be suppressed. For example, the difference between the value A2 of the deterioration information of the pixel PX shown in the data M1 at time T3 and the predetermined value Ath, which is the value of the deterioration information of the pixel PX shown in the data M2, can be made smaller than the difference between the predetermined value Ath, which is the value of the deterioration information of the pixel PX shown in the data M1 at time T2 in FIG. 3, and the value A1 of the deterioration information of the pixel PX shown in the data M2. Therefore, it is possible to suppress burn-in of only some pixels PX whose deterioration information increases relatively quickly among the pixels PX. This makes it possible to suppress the variation in the deterioration degree between the pixels PX of the display device 1, and to suppress the deterioration of the display quality of the displayed image.

[0049] Fig. 6 is a diagram showing the relationship between elapsed time and degradation information for pixel PX in display device 1 according to modification 1 of the embodiment. Fig. 7 is a diagram showing the relationship between elapsed time and drive current for pixel PX in display device 1 according to modification 1 of the embodiment. For example, display control unit 42 may change the amount by which the drive current flowing through pixel PX is reduced in accordance with the degradation information.

[0050] For example, as shown in data M1 of Fig. 6, it is assumed that the degradation information of a pixel PX whose degradation information increases at a relatively fast rate among the multiple pixels PX reaches a predetermined value Ath at time T2. Then, the degradation information determination unit 41 determines that there is a pixel PX whose degradation information reaches the predetermined value Ath at time T2 among the multiple pixels PX, and identifies the pixel PX whose degradation information has reached the predetermined value Ath. In the example shown in data M1 of Fig. 6, the degradation information increases from time T1 to time T2, and the degradation information reaches the predetermined value Ath at time T2.

[0051] Then, as shown in data N1 of FIG. 7, the display control unit 42 generates a gradation signal so that the driving current flowing in response to the video signal to the pixel PX identified by the degradation information determination unit 41 as having the degradation information reach the predetermined value Ath is smaller from time T2 onwards than before time T2, and supplies the gradation signal to the source driver 30. For example, in the example shown in FIG. 7, the display control unit 42 reduces the driving current having a current value B4 flowing in the pixel PX whose degradation information has reached the predetermined value Ath by increasing the amount of reduction from time T2 to time T4, so that the driving current is constant at the current value B2 at time T4. In this way, the display control unit 42 may set the driving current flowing in response to the video signal to the pixel PX whose degradation information has reached the predetermined value Ath as a current value B2, which is reduced by a predetermined percentage from the current value B4 before time T2, from time T2 onwards.

[0052] Then, as shown in data M1 of FIG. 6, the rate of increase of the degradation information of the pixel PX whose degradation information has reached the predetermined value Ath is smaller after time T2 than the rate of increase from time T1 to time T2 before time T2. In the example shown in FIG. 6, the rate at which the rate of increase of the degradation information decreases increases from the predetermined value Ath, which is the value at time T2, to a value A3 at time T4, and the degradation information increases at a constant rate after time T4. In this way, in the example shown in data M1 of FIG. 6, the rate of increase of the degradation information can be quickly reduced from time T2 to time T4. In other words, the rate at which the degradation efficiency of the pixel PX whose degradation information increases relatively quickly can be quickly slowed down from time T2 to time T4.

[0053] On the other hand, for example, as shown in data M2 of Fig. 6, among the multiple pixels PX, the degradation information of a pixel PX whose degradation information increases at a relatively slow rate is a value A1 smaller than the predetermined value Ath at time T2, and reaches the predetermined value Ath at time T3 after time T2. Then, the degradation information determination unit 41 determines that there is a pixel PX among the multiple pixels PX whose degradation information has reached the predetermined value Ath at time T3, and identifies the pixel PX whose degradation information has reached the predetermined value Ath. In the example shown in data M2 of Fig. 6, the degradation information increases from time T1 to time T3, and the degradation information reaches the predetermined value Ath at time T3.

[0054] Then, as shown in data N2 of FIG. 7, the display control unit 42 generates a gradation signal so that the driving current flowing in response to the video signal to the pixel PX identified by the degradation information determination unit 41 as having the degradation information reach the predetermined value Ath is smaller after time T3 than before time T3, and supplies the gradation signal to the source driver 30. For example, in the example shown in FIG. 7, the display control unit 42 reduces the driving current having a current value B3 flowing in the pixel PX whose degradation information has reached the predetermined value Ath by increasing the amount of reduction from time T3 to time T5, so that the driving current is constant at a current value B1 at time T5. In this way, the display control unit 42 may set the driving current flowing in response to the video signal to a pixel PX whose degradation information has reached the predetermined value Ath as a current value B1, which is reduced by a predetermined percentage from the current value B3 before time T3, after time T3.

[0055] Then, as shown in data M2 of FIG. 6, the rate of increase of the degradation information of the pixel PX whose degradation information has reached the predetermined value Ath is smaller after time T3 than the rate of increase from time T1 to time T3 before time T3. In the example shown in FIG. 6, the amount by which the rate of increase of the degradation information decreases increases from the predetermined value Ath, which is the value at time T3, to the value A2 at time T5, and the degradation information increases at a constant rate after time T5. In this way, in the example shown in data M2 of FIG. 6, the rate of increase of the degradation information can be quickly reduced from time T3 to time T5. In other words, the rate of deterioration of the luminous efficiency of the pixel PX whose degradation information is relatively slow to increase can be quickly slowed down from time T3 to time T5.

[0056] In the above example, an example was described in which the amount of current flowing to a pixel PX whose degradation information has reached a predetermined value Ath is reduced by increasing the amount by which the rate of increase in the degradation information of the pixel PX whose degradation information has reached a predetermined value Ath is reduced for a certain period of time (e.g., from time T2 to time T4, or from time T3 to time T5).

[0057] However, on the other hand, the amount of current flowing to a pixel PX whose degradation information has reached a predetermined value Ath may be reduced for a certain period of time (e.g., from time T2 to time T4, or from time T3 to time T5), thereby reducing the amount by which the rate of increase in the degradation information of the pixel PX whose degradation information has reached the predetermined value Ath is reduced for a certain period of time (e.g., from time T2 to time T4, or from time T3 to time T5).

[0058] In this way, the display control unit 42 may control the source driver 30 to change the amount by which the drive current is reduced in accordance with the deterioration information. This also makes it possible to prevent the deterioration of the pixels PX whose deterioration information is equal to or greater than the predetermined value Ath from progressing and causing burn-in. This makes it possible to provide a display device 1 that prevents burn-in of the light-emitting elements 21.

[0059] In addition, as described with reference to FIG. 6, the variation in the deterioration degree between each of the plurality of pixels PX can be suppressed. For example, the difference between the value A3 of the deterioration information of the pixel PX shown in the data M1 at time T5 and the value A2 of the deterioration information of the pixel PX shown in the data M2 at time T5 can be made smaller than the difference between the predetermined value Ath, which is the value of the deterioration information of the pixel PX shown in the data M1 at time T2 in FIG. 6, and the value A1 of the deterioration information of the pixel PX shown in the data M2. Therefore, it is possible to suppress burn-in of only some pixels PX whose deterioration information increases relatively quickly among the plurality of pixels PX. This makes it possible to suppress the variation in the deterioration degree between each of the plurality of pixels PX possessed by the display device 1, and suppress the deterioration of the display quality of the displayed image.

[0060] 8 is a diagram showing a process flow of the control unit 40 in the display device 1 according to the modified example 2 of the embodiment. After the number of the pixels PX whose degradation information has become equal to or greater than the predetermined value Ath becomes equal to or greater than a predetermined ratio, the display control unit 42 may reduce the drive current of each of the pixels PX whose degradation information has become equal to or greater than the predetermined value Ath, compared to the drive current supplied before the degradation information became equal to or greater than the predetermined value Ath.

[0061] As shown in Fig. 8, the deterioration information determination unit 41 sequentially undergoes the processing of step S1 and step S2 described with reference to Fig. 5. In step S2, the deterioration information determination unit 41 refers to the deterioration information accumulation data 51 stored in the memory unit 50, and determines whether or not there is a pixel PX among the multiple pixels PX whose accumulated deterioration information has become equal to or greater than a predetermined value Ath. In step S2, if the deterioration information determination unit 41 determines that there is no pixel PX among the multiple pixels PX whose accumulated deterioration information has become equal to or greater than the predetermined value Ath (No in step S2), the deterioration information determination unit 41 returns to the processing of step S1.

[0062] Furthermore, in step S2, if the degradation information determination unit 41 determines that there is a pixel PX whose accumulated degradation information has become equal to or greater than a predetermined value Ath among the multiple pixels PX (Yes in step S2), then in step S11, the degradation information determination unit 41 adds up the number of pixels whose degradation information has become equal to or greater than the predetermined value. Note that the degradation information determination unit 41 may store the added number of pixels in the storage unit 50 or a memory not shown.

[0063] Next, in step S12, the degradation information determination unit 41 determines whether or not the number of the pixels PX whose degradation information is equal to or greater than a predetermined value is equal to or greater than a predetermined ratio (e.g., 90% of all pixels PX) relative to the number of the pixels PX provided on the display panel 10. If, in step S12, the degradation information determination unit 41 determines that the number of the pixels PX whose degradation information is equal to or greater than a predetermined value is not equal to or greater than the predetermined ratio relative to the number of the pixels PX provided on the display panel 10 (No in step S12), the degradation information determination unit 41 returns to the processing of step S1.

[0064] Also, in step S12, when the deterioration information determination unit 41 determines that the number of pixels PX whose deterioration information has become equal to or greater than the predetermined value has reached a predetermined ratio or more with respect to the number of pixels PX provided on the display panel 10 (if Yes in step S12), in step S13, the display control unit 42 controls the source driver 30 so that the drive current supplied to the pixels PX whose deterioration information has been determined by the deterioration information determination unit 41 to have become equal to or greater than the predetermined value Ath among the pixels PX provided on the display panel 10 is smaller than the drive current supplied before the deterioration information became equal to or greater than the predetermined value Ath. In other words, for example, the display control unit 42 reduces a value representing the luminance value indicated by the grayscale signal supplied to the source driver 30 so that the drive current supplied to the pixels PX whose deterioration information has become equal to or greater than the predetermined value Ath is smaller than the drive current supplied before the deterioration information became equal to or greater than the predetermined value Ath.

[0065] In this way, when the deterioration information determination unit 41 determines that there is a pixel PX whose deterioration information has become equal to or greater than the predetermined value Ath, if the proportion of the pixels PX whose deterioration information has become equal to or greater than the predetermined value Ath among the pixels PX provided on the display panel 10 becomes equal to or greater than a predetermined proportion, the deterioration information determination unit 41 controls the source driver 30 so that the drive current supplied to each of the pixels PX whose deterioration information has become equal to or greater than the predetermined value Ath becomes smaller than the drive current supplied to each of the pixels PX whose deterioration information has become equal to or greater than the predetermined value Ath before the deterioration information became equal to or greater than the predetermined value Ath.

[0066] This makes it possible to reduce the processing load on the control unit 40 compared to a case where the driving current for each pixel of the plurality of pixels provided on the display panel whose degradation information has reached a predetermined value or more is sequentially reduced from the driving current supplied before the degradation information reached the predetermined value or more. This makes it possible to prevent a decrease in the processing speed of the control unit 40.

[0067] 9 is a diagram showing a schematic configuration of a display device 1 according to a third modified example of the embodiment. When the display control unit 42 reduces the drive current of a pixel PX whose degradation information has become equal to or greater than a predetermined value Ath, the display control unit 42 may also reduce the drive current of at least one pixel PX adjacent to the pixel PX whose degradation information has become equal to or greater than the predetermined value Ath. As shown in FIG. 9, a pixel PXa whose degradation information increases at a relatively fast rate is adjacent to a pixel PXb whose degradation information increases at a relatively slow rate.

[0068] Fig. 10 is a diagram showing the relationship between elapsed time and degradation information for pixels PXa and PXb in a display device 1 according to a third modification of the embodiment. Fig. 11 is a diagram showing the relationship between elapsed time and drive current for pixels PXa and PXb in a display device 1 according to a third modification of the embodiment.

[0069] In Fig. 10, data M1a shown by a solid line represents the change in degradation information of pixel PXa. In Fig. 10, data M2b shown by a dashed line represents the change in degradation information of pixel PXb. In Fig. 11, data N1a shown by a solid line represents the change in drive current of pixel PXa. In Fig. 11, data N2b shown by a dashed line represents the change in drive current of pixel PXb.

[0070] For example, as shown in data M1a of FIG. 10, it is assumed that the deterioration information of pixel PXa, whose deterioration information increases at a relatively fast rate among the multiple pixels PX, reaches a predetermined value Ath at time T2. Then, the deterioration information determination unit 41 determines that there is a pixel PXa among the multiple pixels PX whose deterioration information reaches the predetermined value Ath at time T2, and identifies the pixel PXa whose deterioration information has reached the predetermined value Ath. In the example shown in data M1 of FIG. 10, the deterioration information increases from time T1 to time T2, and the deterioration information reaches the predetermined value Ath at time T2. In addition, the deterioration information determination unit 41 identifies at least one pixel PX adjacent to the pixel PXa whose deterioration information has reached the predetermined value Ath. In this modification example 3, the deterioration information determination unit 41 identifies a pixel PXb adjacent to the pixel PXa whose deterioration information has reached the predetermined value Ath.

[0071] 11, the display control unit 42 generates a gradation signal so that the drive current flowing in response to the video signal to the pixel PXa identified by the degradation information determination unit 41 as having the degradation information reach the predetermined value Ath is smaller after time T2 than before time T2, and supplies the gradation signal to the source driver 30. For example, in the example shown in FIG 11, the display control unit 42 reduces the drive current having a current value B4 flowing to the pixel PXa whose degradation information has reached the predetermined value Ath by increasing the amount of reduction from time T2 to time T4, so that the drive current becomes constant at a current value B2 at time T3.

[0072] 11, the display control unit 42 generates a gradation signal so that the drive current flowing in response to the video signal to pixel PXb adjacent to pixel PXa identified by the degradation information determination unit 41 as having degradation information reaching the predetermined value Ath is smaller after time T2 than before time T2, and supplies the gradation signal to the source driver 30. For example, in the example shown in FIG. 11, the display control unit 42 reduces the drive current having a current value B3 flowing to pixel PXb adjacent to pixel PXa whose degradation information has reached the predetermined value Ath by increasing the amount of reduction from time T2 to time T3, so that the drive current is constant at a current value B1 at time T3.

[0073] As a result, as shown in data M1a in Fig. 10, the rate of increase in the degradation information of pixel PXa whose degradation information has reached the predetermined value Ath becomes slower after time T2 compared to the rate of increase from time T1 to time T2 before time T2. In the example shown in Fig. 10, the data M1a shows an increasing amount at which the rate of increase in the degradation information decreases from the predetermined value Ath, which is the value at time T2, to a value A3 at time T3, and the value of the degradation information increases at a constant rate after time T3.

[0074] In addition, as shown in data M2b in Fig. 10, the rate of increase in the degradation information of pixel PXb adjacent to pixel PXa whose degradation information has reached a predetermined value Ath is smaller after time T2 than the rate of increase from time T1 to time T2 before time T2. In the example shown in Fig. 10, the rate at which the rate of increase in the degradation information decreases increases from value A1 at time T2 to value A2 at time T3, and the degradation information increases at a constant rate after time T3.

[0075] In this way, when the display control unit 42 reduces the drive current of the pixel PXa of which the deterioration information is equal to or greater than the predetermined value Ath among the pixels PX, it controls the source driver 30 so that the drive current supplied to the pixel PXb adjacent to the pixel PXa of which the deterioration information is equal to or greater than the predetermined value Ath is also reduced. This makes it possible to suppress burn-in of the pixel PXa, which is prone to deterioration, and to suppress deterioration of the pixel PXb adjacent to the pixel PXa, which is prone to deterioration. In addition, since the drive current flowing through each of the adjacent pixels PXa and PXb is reduced, it is possible to suppress the occurrence of a difference in the luminance of each of them. As a result, it is possible to suppress the deterioration of the display quality of the image displayed by the display device 1.

[0076] The elements appearing in the above-described embodiment and modified examples may be combined as appropriate to the extent that no contradiction occurs. [Explanation of symbols]

[0077] 1: display device, 10: display panel, 11: display area, 13: gate driver, 20: pixel circuit, 21: light emitting element, 30: source driver (drive circuit), 40: control unit, 41: deterioration information determination unit, 42: display control unit, 50: storage unit, 51: deterioration information accumulation data, PX·PXa·PXb: pixels

Claims

1. A display panel provided with a plurality of pixels including light-emitting elements; A drive circuit for supplying a drive current to each of the plurality of pixels; a control unit that controls the drive circuit so that the drive current corresponding to a video signal is supplied to each of the plurality of pixels; The control unit is determining whether or not there is a pixel among the plurality of pixels whose degradation information indicating a degree of degradation of the luminous efficiency is equal to or greater than a predetermined value; When it is determined that there is a pixel whose degradation information is equal to or greater than the predetermined value, a display device which, when a proportion of the plurality of pixels whose degradation information is equal to or greater than the predetermined value reaches or exceeds a predetermined proportion, controls the drive circuit so that the drive current supplied to each of the plurality of pixels whose degradation information is equal to or greater than the predetermined value becomes smaller than the drive current before the degradation information reached or exceeds the predetermined value.

2. A display panel provided with a plurality of pixels including light-emitting elements; A drive circuit for supplying a drive current to each of the plurality of pixels; a control unit that controls the drive circuit so that the drive current corresponding to a video signal is supplied to each of the plurality of pixels; The control unit is determining whether or not there is a pixel among the plurality of pixels whose degradation information indicating a degree of degradation of the luminous efficiency is equal to or greater than a predetermined value; When it is determined that there is a pixel whose degradation information is equal to or greater than the predetermined value, adding up the number of pixels whose degradation information is equal to or greater than the predetermined value; Furthermore, when a ratio of the number of pixels whose deterioration information is equal to or greater than the predetermined value to the total number of the plurality of pixels becomes equal to or greater than a predetermined ratio, the display device controls the drive circuit so that the drive current supplied to each of the plurality of pixels whose deterioration information is equal to or greater than the predetermined value becomes smaller than that before the deterioration information became equal to or greater than the predetermined value.

3. A display panel provided with a plurality of pixels including light-emitting elements; A drive circuit for supplying a drive current to each of the plurality of pixels; a control unit that controls the drive circuit so that the drive current corresponding to a video signal is supplied to each of the plurality of pixels; The control unit is determining whether or not there is a pixel among the plurality of pixels whose degradation information indicating a degree of degradation of the luminous efficiency is equal to or greater than a predetermined value; when it is determined that there is a pixel whose deterioration information has reached or exceeded the predetermined value, the drive circuit is controlled so that the drive current supplied to the pixel is smaller than that before the deterioration information reached or exceeded the predetermined value; The control unit controls the drive circuit so that when reducing the drive current of the pixel whose degradation information has become equal to or greater than the predetermined value, the drive current supplied to a pixel adjacent to the pixel whose degradation information has become equal to or greater than the predetermined value is also reduced.

4. The display device according to claim 1 , wherein the degradation information is a time-integrated value of power consumption supplied to each of the plurality of pixels.

5. The display device according to claim 1 , wherein the control unit controls the drive circuit to change an amount by which the drive current is reduced in accordance with the degradation information.

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