Foldable display device

Abstract

Disclosed is a foldable display device for compensating for degradation of a flexible display panel, for stopping performing a degradation compensation operation in a miscompensation period in which the display brightness is greater than a target brightness by sensing a display brightness, which is a brightness of a test image, using an optical module provided in a first display area of the flexible display panel, and performing a degradation compensation operation in a compensation period in which the display brightness is less than or equal to the target brightness.

Description

Technical Field

[0001] Embodiments of the inventive concept relate to a foldable display device. Background Art

[0002] Generally, a display device may include a display panel and a display panel driver. The display panel may include gate lines, data lines and pixels. The display panel driver may include a gate driver for providing a gate signal to the gate line, a data driver for providing a data voltage to the data line, and a drive controller for controlling the gate driver and the data driver.

[0003] The display brightness of each of the pixels may be determined based on the intensity of the driving current of each of the pixels, the intensity of the driving current may be determined by the level of the data voltage, and the level of the data voltage may be determined based on the grayscale of the input image data received by the driving controller.

[0004] Meanwhile, since pixels degrade with use, display brightness according to the same grayscale may increase or decrease. Therefore, a degradation compensation operation may be performed to compensate display brightness based on a degradation amount defined as a brightness reduction rate according to a stress value of each pixel. Summary of the invention

[0005] Embodiments of the inventive concept provide a foldable display device that compensates for degradation of a flexible display panel to improve display quality.

[0006] In an embodiment of a foldable display device conceived according to the present invention, the foldable display device includes: a flexible display panel, including a folding line, a first display area arranged on a first side of the folding line, and a second display area arranged on a second side of the folding line for displaying a test image; an optical module, arranged in the first display area to perform a sensing operation of sensing display brightness, the display brightness is the brightness of the test image; and a degradation compensator, configured to perform a degradation compensation operation of compensating the display brightness according to a brightness compensation value when the display brightness is less than or equal to a target brightness, and not perform the degradation compensation operation when the display brightness is greater than the target brightness.

[0007] In an embodiment, when the folding angle, which is an angle between the first display area and the second display area, is less than or equal to a reference angle, the optical module may perform a sensing operation.

[0008] In an embodiment, the reference angle may include 0 degrees.

[0009] In an embodiment, a sensing area may be determined by a folding angle, the sensing area being an area of ​​a test image sensed by the optical module.

[0010] In an embodiment, the sensing area may be smaller than the area of ​​the flexible display panel.

[0011] In an embodiment, when the folding angle is 0 degrees, the sensing area may be equal to the area of ​​the optical module.

[0012] In an embodiment, the degradation compensation operation may be performed on the entire flexible display panel based on the sensing area.

[0013] In an embodiment, the sensing area may have a brightness compensation value equal to a brightness compensation value of the entire flexible display panel.

[0014] In an embodiment, when the sensing operation is performed, a test image may be displayed in the second display area.

[0015] In an embodiment, the degradation compensator may include a lookup table including brightness compensation values ​​corresponding to stress values ​​of the flexible display panel.

[0016] In an embodiment, the degradation compensator may use a lookup table to compensate display brightness according to the brightness compensation value.

[0017] In an embodiment, the degradation compensator may include: a memory device configured to store a stress value of the flexible display panel; a compensation value calculator configured to calculate a brightness compensation value based on the stress value; and a compensation determiner configured to determine whether to perform a degradation compensation operation by comparing the display brightness with the target brightness, and when the degradation compensation operation is performed, compensate the display brightness according to the brightness compensation value.

[0018] In an embodiment, the optical module may include a camera module or an optical fingerprint sensor.

[0019] According to the display device, the display device can sense the display brightness as the brightness of the test image using an optical module provided in the first display area of ​​the flexible display panel, and does not perform the degradation compensation operation in the error compensation period in which the display brightness is greater than the target brightness. In addition, the degradation compensation operation is performed in the compensation period in which the display brightness is less than or equal to the target brightness. Therefore, the foldable display device can selectively perform the degradation compensation operation in the compensation period to improve the display quality of the foldable display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other features of the embodiments of the present inventive concept will become more apparent by describing the embodiments of the present inventive concept in detail with reference to the accompanying drawings, in which:

[0021] Figure 1 is a perspective view showing a foldable display device according to one embodiment of the present disclosure;

[0022] Figure 2 It is shown Figure 1 A block diagram of a foldable display device;

[0023] Figure 3 It is shown that the Figure 2 A circuit diagram of an example of a pixel in a foldable display device;

[0024] FIG. 4A to FIG. 4D is a graph showing display brightness according to stress values ​​of pixels;

[0025] Figure 5 It is shown that the Figure 2 A block diagram of a camera module and a degradation compensator in a foldable display device;

[0026] Figure 6 and Figure 7 is shown using the included Figure 2 A schematic diagram of performing a degradation compensation operation on a camera module in a foldable display device;

[0027] Fig. 8A and Figure 8B It is shown by Figure 2 The degradation compensator is relative to Figure 4A A graph showing a degradation compensation operation performed by the flexible display panel A;

[0028] Fig. 9A and Fig. 9B It is shown by Figure 2 The degradation compensator is relative to Figure 4B A graph showing a degradation compensation operation performed by the flexible display panel B;

[0029] Fig. 10A and Fig. 10B It is shown by Figure 2 The degradation compensator is relative to Figure 4C A graph showing a degradation compensation operation performed by the flexible display panel C;

[0030] Fig.11 is a flow chart illustrating a method for compensating for degradation of a flexible display panel according to one embodiment of the present disclosure;

[0031] Fig.12 is a perspective view showing a foldable display device according to an embodiment;

[0032] Fig.13 It is shown Fig.12 A block diagram of a foldable display device; and

[0033] Fig.14 is a block diagram illustrating an electronic device. DETAILED DESCRIPTION

[0034] Hereinafter, the present disclosure will be described in more detail with reference to the accompanying drawings.

[0035] Figure 1 is a perspective view showing a foldable display device 10 according to one embodiment of the present disclosure. Figure 2 It is shown Figure 1 1 is a block diagram of a foldable display device 10.

[0036] refer to Figure 1 and Figure 2 According to one embodiment of the present disclosure, the foldable display device 10 may be a display device using flexible display technology. The flexible display technology may refer to a technology using a flexible display panel that can be bent without being damaged.

[0037] The foldable display device 10 includes a flexible display panel 100 and a display panel driver. The display panel driver may include a driving controller 200, a gate driver 300, a data driver 500, an emission driver 600, and a degradation compensator 700. The foldable display device 10 may further include an optical module. In one embodiment, the optical module may be a camera module CM.

[0038] For example, the driving controller 200 and the data driver 500 may be integrally formed. For example, the driving controller 200, the data driver 500 and the emission driver 600 may be integrally formed. At least the driving controller 200 and the data driver 500 are integrally formed in a driving module, which may be referred to as a timing controller embedded data driver (TED).

[0039] The flexible display panel 100 may include a display portion for displaying an image and a peripheral portion disposed adjacent to the display portion.

[0040] The flexible display panel 100 may include a folding line FL, a first display area DA1 disposed on a first side of the folding line FL, and a second display area DA2 disposed on a second side of the folding line FL. The flexible display panel 100 may be folded around the folding line FL. When the flexible display panel 100 is folded, a folding angle FA, which is an angle between the first display area DA1 and the second display area DA2, may decrease. In one embodiment, the folding angle FA may range from 0 degrees to 180 degrees. In another embodiment, the folding angle FA may range from 0 degrees to 360 degrees.

[0041] For example, in this embodiment, the flexible display panel 100 may be an organic light emitting diode display panel including an organic light emitting diode. For example, the flexible display panel 100 may be a quantum dot organic light emitting diode display panel including an organic light emitting diode and a quantum dot color filter. For example, the flexible display panel 100 may be a quantum dot nano light emitting diode display panel including a nano light emitting diode and a quantum dot color filter.

[0042] The flexible display panel 100 may include a gate line GL, a data line DL, an emission line EML, and pixels P, each of which is electrically connected to the gate line GL, the data line DL, and the emission line EML. The gate line GL may extend in a first direction, the data line DL may extend in a second direction intersecting the first direction, and the emission line EML may extend in the first direction.

[0043] The drive controller 200 may receive input image data IMG and an input control signal CONT from an external device (not shown). For example, the input image data IMG may include red image data, green image data, and blue image data. The input image data IMG may include white image data. The input image data IMG may include magenta image data, yellow image data, and cyan image data. The input control signal CONT may include a master clock signal and a data enable signal. The input control signal CONT may also include a vertical synchronization signal and a horizontal synchronization signal.

[0044] The driving controller 200 may generate a first control signal CONT1 , a second control signal CONT2 , a third control signal CONT3 , and a data signal DATA based on input image data IMG and an input control signal CONT.

[0045] The driving controller 200 may generate a first control signal CONT1 for controlling the operation of the gate driver 300 based on the input control signal CONT, and output the first control signal CONT1 to the gate driver 300. The first control signal CONT1 may include a vertical start signal and a gate clock signal.

[0046] The driving controller 200 may generate a second control signal CONT2 for controlling the operation of the data driver 500 based on the input control signal CONT, and output the second control signal CONT2 to the data driver 500. The second control signal CONT2 may include a horizontal start signal and a load signal.

[0047] The driving controller 200 may generate a data signal DATA based on the input image data IMG. The driving controller 200 may output the data signal DATA to the data driver 500.

[0048] The gate driver 300 may generate a gate signal for driving the gate line GL in response to the first control signal CONT1 received from the driving controller 200. The gate driver 300 may output the gate signal to the gate line GL.

[0049] The data driver 500 may receive the second control signal CONT2 and the data signal DATA from the driving controller 200. The data driver 500 may convert the data signal DATA into an analog type data voltage. The data driver 500 may output the data voltage to the data line DL.

[0050] The emission driver 600 generates an emission signal for driving the emission lines EML in response to the third control signal CONT3 received from the driving controller 200. The emission driver 600 may output the emission signal to the emission lines EML.

[0051] The camera module CM may be disposed in the first display area DA1. The camera module CM may photograph an object positioned in front of the flexible display panel 100 or sense external brightness. In other words, the camera module CM may include a brightness sensor and sense external brightness through the brightness sensor. In the present embodiment, the flexible display panel 100 may display a test image in the second display area DA2, and the camera module CM may sense a display brightness LUM_D as the brightness of the test image.

[0052] The degradation compensator 700 may receive display brightness LUM_D from the camera module CM and receive input image data IMG from the driving controller 200. The pixels P included in the flexible display panel 100 may be degraded according to use. The degradation compensator 700 may generate a stress value for each of the pixels P based on the input image data IMG. The stress value may refer to the degree of degradation of the pixel P. The degradation compensator 700 may generate a data signal DATA by compensating the input image data IMG based on the input image data IMG, the display brightness LUM_D, and the stress value. The degradation compensator 700 may output the data signal DATA to the data driver 500.

[0053] In the present embodiment, the degradation compensator 700 is illustrated as being formed independently of the drive controller 200 , but the present disclosure is not limited thereto. In another embodiment, the degradation compensator 700 may be formed integrally with the drive controller 200 .

[0054] Figure 3 It is shown that the Figure 2 1 is a circuit diagram of an example of a pixel P in the foldable display device 10.

[0055] refer to Figures 1 to 3 , the pixel P may include first to seventh transistors T1 to T7 and a light emitting element EE.

[0056] The first transistor T1 (ie, a driving transistor) may include a gate electrode connected to the first node N1, a first electrode connected to the second node N2, and a second electrode connected to the third node N3.

[0057] The second transistor T2 may include a gate electrode to which the data write gate signal GW is applied, a first electrode to which the data voltage VDATA is applied, and a second electrode connected to the second node N2. The data voltage VDATA may be applied to the pixel P according to the data write gate signal GW.

[0058] The third transistor T3 may include a gate electrode to which the compensation gate signal GC is applied, a first electrode connected to the first node N1, and a second electrode connected to the third node N3. The threshold voltage of the first transistor T1 may be compensated according to the compensation gate signal GC.

[0059] The fourth transistor T4 may include a gate electrode applied with the data initialization gate signal GI, a first electrode applied with the initialization voltage VINIT, and a second electrode connected to the first node N1. According to the data initialization gate signal GI, the gate electrode of the first transistor T1 may be initialized to the initialization voltage VINIT.

[0060] The fifth transistor T5 may include a gate electrode to which the emission signal EM is applied, a first electrode to which the first driving voltage ELVDD is applied, and a second electrode connected to the second node N2.

[0061] The sixth transistor T6 may include a gate electrode to which the emission signal EM is applied, a first electrode connected to the third node N3, and a second electrode connected to the anode electrode of the light emitting element EE.

[0062] The seventh transistor T7 may include a gate electrode to which a light emitting element initialization gate signal GB is applied, a first electrode to which a light emitting element initialization voltage VAINIT is applied, and a second electrode connected to an anode electrode of the light emitting element EE. According to the light emitting element initialization gate signal GB, the anode electrode of the light emitting element EE may be initialized to the light emitting element initialization voltage VAINIT.

[0063] The light emitting element EE may include an anode electrode and a cathode electrode to which a second driving voltage ELVSS is applied. The second driving voltage ELVSS may be lower than the first driving voltage ELVDD.

[0064] The pixel P may further include a storage capacitor CST including a first electrode to which the first driving voltage ELVDD is applied and a second electrode connected to the first node N1. The storage capacitor CST may store a voltage corresponding to the data voltage VDATA.

[0065] The driving current ID of the pixel P may flow to the fifth transistor T5, the first transistor T1, and the sixth transistor T6 in sequence to drive the light emitting element EE. The brightness of the light emitting element EE may be determined by the intensity of the driving current ID. The intensity of the driving current ID may be determined by the level of the data voltage VDATA. The level of the data voltage VDATA may be determined by the grayscale of the input image data IMG.

[0066] When all of the transistors included in the pixel P are P-type transistors, flickering may be caused in low-frequency driving due to the leakage current of the transistor. Therefore, some of the transistors included in the pixel P may be N-type transistors. In the present embodiment, the third transistor T3 and the fourth transistor T4 may be N-type transistors, and the first transistor T1, the second transistor T2, the fifth transistor T5, the sixth transistor T6, and the seventh transistor T7 may be P-type transistors. However, the present disclosure is not limited thereto. The present disclosure may be applied to pixels including only P-type transistors, or may be applied to pixels including only N-type transistors.

[0067] FIG. 4A to FIG. 4D is a graph showing display luminance LUM_D according to stress value SV of a pixel P.

[0068] refer to Figures 1 to 4D , the pixel P may degrade according to use. As the pixel P is used, the stress value SV may increase. The stress value SV may refer to the degree of degradation of the pixel P. For example, when the use time of the pixel P increases, the pixel P may further degrade. For example, when the grayscale of the input image data IMG, the data voltage VDATA, or the driving current ID increases, the pixel P may further degrade.

[0069] The display brightness LUM_D may be increased or decreased according to the stress value SV. The period in which the display brightness LUM_D increases according to the stress value SV may be referred to as the rising period RP, and the period in which the display brightness LUM_D decreases according to the stress value SV may be referred to as the falling period FP. Generally, it may be difficult to predict the slope of the degradation curve in the rising period RP, and in the falling period FP, because the slope of the degradation curve is constant, it may be easy to predict the slope of the degradation curve. In addition, the distribution of the stress value SV may be large in the rising period RP, and the distribution of the stress value SV may be small in the falling period FP. The degradation amount ΔLUM_D may be calculated based on the stress value SV and the display brightness LUM_D. The degradation amount ΔLUM_D may be the degree of reduction of the display brightness LUM_D compared to the target brightness TL. For example, when the display brightness LUM_D is greater than the target brightness TL, the degradation amount ΔLUM_D may have a negative value. For example, when the display brightness LUM_D is equal to the target brightness TL, the degradation amount ΔLUM_D may be 0. For example, when the display brightness LUM_D is less than the target brightness TL, the degradation amount ΔLUM_D may have a positive value. In one embodiment, the target brightness TL may be the display brightness LUM_D at the zero stress value SV0 of the foldable display device 10 . FIG. 4A to FIG. 4D Degradation curves G1 , G2 , and G3 representing the display luminance LUM_D according to the stress value SV are shown.

[0070] Even when the foldable display device is manufactured under the same conditions (such as temperature, humidity, material and process time), the characteristics of the flexible display panel may be different for each flexible display panel. Therefore, when the foldable display device is manufactured, the display brightness according to the same grayscale can be set to the target brightness in consideration of the characteristics of the flexible display panel. When the foldable display device 10 is manufactured, the stress value SV may be a zero stress value SV0. This process may be performed by an inspection device (not shown) that exists separately from the foldable display device 10. The inspection device can sense the display brightness LUM_D under strict conditions in the manufacturing process, and can set the display brightness LUM_D to the target brightness TL. However, the degradation amount ΔLUM_D according to the use of the flexible display panel 100 may be different according to the characteristics of the flexible display panel 100.

[0071] For example, flexible display panel A, flexible display panel B, and flexible display panel C can be manufactured under the same conditions. Figure 4A As shown in , the display luminance LUM_D according to the stress value SV may be dispersed in the flexible display panel A, and the degradation curve G1 of the flexible display panel A may be represented based on the dispersed display luminance LUM_D of the flexible display panel A. Figure 4BAs shown in , the display brightness LUM_D according to the stress value SV may be dispersed in the flexible display panel B, and the degradation curve G2 of the flexible display panel B may be represented based on the dispersed display brightness LUM_D of the flexible display panel B. Figure 4C As shown in , the display luminance LUM_D according to the stress value SV may be dispersed in the flexible display panel C, and the degradation curve G3 of the flexible display panel C may be represented based on the dispersed display luminance LUM_D of the flexible display panel C. Figure 4D , a degradation curve G1 of the flexible display panel A, a degradation curve G2 of the flexible display panel B, and a degradation curve G3 of the flexible display panel C are shown together. In the falling period FP, the difference LD1 between the degradation curve G1 of the flexible display panel A and the degradation curve G2 of the flexible display panel B may be constant. In the falling period FP, the difference LD2 between the degradation curve G2 of the flexible display panel B and the degradation curve G3 of the flexible display panel C may be constant.

[0072] For example, Figure 4A As shown in , the display brightness LUM_D of the flexible display panel A can be 100nit (100%) at the zero stress value SV0, 102nit (102%) at the first stress value SV1, 100nit (100%) at the third stress value SV3, and 95nit (95%) at the fourth stress value SV4. In this case, the degradation amount ΔLUM_D of the flexible display panel A can be 0nit (0%) at the zero stress value SV0, -2nit (-2%) at the first stress value SV1, 0nit (0%) at the third stress value SV3, and 5nit (5%) at the fourth stress value SV4. In the case of the flexible display panel A, the rising period RP can be the period between the zero stress value SV0 and the first stress value SV1, and the falling period FP can be the period after the first stress value SV1.

[0073] For example, Figure 4BAs shown in , the display brightness LUM_D of the flexible display panel B can be 100nit (100%) at the zero stress value SV0, 101nit (101%) at the first stress value SV1, 100nit (100%) at the second stress value SV2, and 90nit (90%) at the fourth stress value SV4. In this case, the degradation amount ΔLUM_D of the flexible display panel B can be 0nit (0%) at the zero stress value SV0, -1nit (-1%) at the first stress value SV1, 0nit (0%) at the second stress value SV2, and 10nit (10%) at the fourth stress value SV4. The rising period RP can be a period between the zero stress value SV0 and the first stress value SV1, and the falling period FP can be a period after the first stress value SV1.

[0074] For example, Figure 4C As shown in , the display brightness LUM_D of the flexible display panel C may be 100nit (100%) at the zero stress value SV0, 98nit (98%) at the first stress value SV1, and 85nit (85%) at the fourth stress value SV4. In this case, the degradation amount ΔLUM_D of the flexible display panel C may be 0nit (0%) at the zero stress value SV0, 2nit (2%) at the first stress value SV1, and 15nit (15%) at the fourth stress value SV4. The falling period FP may be a period after the zero stress value SV0, and the rising period RP may not exist.

[0075] Unlike the above manufacturing process, after manufacturing the foldable display device 10, it is difficult to require the user to use an inspection device to measure the display brightness LUM_D. Therefore, the reference degradation curve GR can be generated by averaging the display brightness LUM_D according to the stress value SV of each of the flexible display panels manufactured under the same conditions. The brightness compensation value LCV according to the stress value SV can be calculated based on the reference degradation curve GR, and the brightness compensation value LCV according to the stress value SV can be stored in a lookup table. The degradation compensator 700 may include a lookup table, and generates a brightness compensation value LCV according to the stress value SV based on the lookup table to compensate the display brightness LUM_D according to the brightness compensation value LCV.

[0076] For example, the reference degradation curve GR may be generated based on the degradation curves G1, G2, and G3 of the flexible display panel A, B, and C. Assume that the reference degradation curve GR is the same as the degradation curve G2 of the flexible display panel B.

[0077] For example, the degradation amount ΔLUM_D of the flexible display panel A at the fourth stress value SV4 may be 5 nit (5%), the degradation amount ΔLUM_D of the flexible display panel B at the fourth stress value SV4 may be 10 nit (10%), and the degradation amount ΔLUM_D of the flexible display panel C at the fourth stress value SV4 may be 15 nit (15%). When it is assumed that the reference degradation curve GR is the same as the degradation curve G2 of the flexible display panel B, the lookup table may be generated based on the reference degradation curve GR. In all of the flexible display panels A, B, and C, the brightness compensation value LCV according to the stress value SV calculated based on the lookup table may be 10 nit.

[0078] Figure 5 It is shown that the Figure 2 1 is a block diagram of a camera module CM and a degradation compensator 700 in a foldable display device 10.

[0079] refer to Figures 1 to 5 , the degradation compensator 700 may include a memory device 710 , a compensation value calculator 720 , and a compensation determiner 730 .

[0080] The memory device 710 may receive input image data IMG from the driving controller 200 and accumulate the input image data IMG to generate a stress value SV for each of the pixels P. In an embodiment, the memory device 710 may be configured to store the stress value SV of the flexible display panel 100 .

[0081] The compensation value calculator 720 may receive input image data IMG from the driving controller 200 and receive the stress value SV from the memory device 710. The compensation value calculator 720 may generate a brightness compensation value LCV based on the input image data IMG and the stress value SV by using a lookup table LUT. In an embodiment, the compensation value calculator 720 may be configured to calculate the brightness compensation value LCV based on the stress value SV.

[0082] The compensation determiner 730 may receive the display brightness LUM_D from the camera module CM and accept the brightness compensation value LCV from the compensation value calculator 720. The compensation determiner 730 may determine whether to perform a degradation compensation operation by comparing the display brightness LUM_D with the target brightness TL. When the display brightness LUM_D is greater than the target brightness TL, the compensation determiner 730 may not perform the degradation compensation operation. In this case, the compensation determiner 730 may output the data signal DATA to the drive controller 200 without compensating the display brightness LUM_D. The period in which the display brightness LUM_D is greater than the target brightness TL may be referred to as a miscompensation period. When the display brightness LUM_D is less than or equal to the target brightness TL, the compensation determiner 730 may perform a degradation compensation operation. When the compensation determiner 730 performs the degradation compensation operation, the compensation determiner 730 may compensate the display brightness LUM_D according to the brightness compensation value LCV and output the data signal DATA to the drive controller 200. The period in which the display brightness LUM_D is less than or equal to the target brightness TL may be referred to as a compensation period.

[0083] Figure 6 and Figure 7 is shown using the included Figure 2 Schematic diagram of the camera module CM in the foldable display device 10 performing a degradation compensation operation.

[0084] refer to Figures 1 to 7As described above, unlike the above manufacturing process, after manufacturing the foldable display device 10, it is difficult to require the user to measure the display brightness LUM_D by using an inspection device. However, the flexible display panel 100 can be folded around the folding line FL. Therefore, when the folding angle FA is reduced to a predetermined angle or less, the camera module CM set in the first display area DA1 can capture an image of the flexible display panel 100 in the second display area DA2. The area of ​​the test image sensed by the camera module CM may be referred to as a sensing area. The sensing area SA, which is the area of ​​the sensing area, may be determined by the folding angle FA, and the sensing area SA may be smaller than the area of ​​the flexible display panel 100. Therefore, since the display brightness LUM_D of the flexible display panel 100 other than the sensing area cannot be sensed, the brightness compensation value LCV of the sensing area SA may be equal to the brightness compensation value LCV of the entire flexible display panel 100. For example, the sensing area SA may decrease as the folding angle FA decreases, and the area of ​​the image capture area may increase as the folding angle FA increases. In particular, when the folding angle FA is less than or equal to the reference angle, the flexible display panel 100 may display a test image in the second display area DA2, and the camera module CM may perform a sensing operation of sensing the brightness of the test image displayed in the second display area DA2. The reference angle may be an angle set to perform a sensing operation under strict conditions such as during the above manufacturing process. In addition, the reference angle may be an angle indicating that the user is not using the foldable display device 10. As the folding angle FA decreases, the reliability of the sensing operation may increase. In one embodiment, the reference angle may be 0 degrees. For example, when the reference angle is 0 degrees, the sensing area SA may be the same as the area CMA of the camera module CM.

[0085] As described above, because the sensing area SA is smaller than the area of ​​the flexible display panel 100 , the compensation value calculator 720 may perform the degradation compensation operation on the entire flexible display panel 100 based on the sensing area SA.

[0086] Fig. 8A and Figure 8B It is shown by Figure 2 The degradation compensator 700 is relative to Figure 4A A graph showing the degradation compensation operation performed by the flexible display panel A.

[0087] refer to Figures 1 to 8B , the degradation compensator 700 may perform a degradation compensation operation on the flexible display panel A.

[0088] The compensation value calculator 720 may calculate the brightness compensation value LCV based on the input image data IMG and the stress value SV by using a lookup table LUT. For example, the brightness compensation value LCV may be calculated as -1 nit at the first stress value SV1, the brightness compensation value LCV may be calculated as 0 nit at the third stress value SV3, and the brightness compensation value LCV may be calculated as 10 nit at the fourth stress value SV4.

[0089] The compensation determiner 730 may receive the display brightness LUM_D and the brightness compensation value LCV. The compensation determiner 730 may compare the display brightness LUM_D with the target brightness TL to determine that a period between the zero stress value SV0 and the third stress value SV3 (the period in which the display brightness LUM_D is greater than the target brightness TL) is the miscompensation period MCP, and may determine that a period after the third stress value SV3 (the period in which the display brightness LUM_D is less than or equal to the target brightness TL) is the compensation period CP.

[0090] The compensation determiner 730 may not perform the degradation compensation operation in the miscompensation period MCP. Figure 8B As shown in , the compensation determiner 730 may output the data signal DATA to the driving controller 200 without compensating for the display brightness LUM_D.

[0091] The compensation determiner 730 may perform a degradation compensation operation during the compensation period CP. Figure 8B As shown in , the compensation determiner 730 may compensate for the display brightness LUM_D according to the brightness compensation value LCV to output the data signal DATA to the driving controller 200 .

[0092] As described above, the degradation compensator 700 may perform a process similar to Figure 8B The degradation compensation operation of the degradation curve G1' of the flexible display panel A.

[0093] Fig. 9A and Fig. 9B It is shown by Figure 2 The degradation compensator 700 is relative to Figure 4B A graph showing the degradation compensation operation performed by the flexible display panel B.

[0094] refer to Figures 1 to 9B , the degradation compensator 700 may perform a degradation compensation operation with respect to the flexible display panel B.

[0095] The compensation value calculator 720 may calculate the brightness compensation value LCV based on the input image data IMG and the stress value SV by using a lookup table LUT. For example, the brightness compensation value LCV may be calculated as -1 nit at the first stress value SV1, the brightness compensation value LCV may be calculated as 0 nit at the second stress value SV2, and the brightness compensation value LCV may be calculated as 10 nit at the fourth stress value SV4.

[0096] The compensation determiner 730 may receive the display brightness LUM_D and the brightness compensation value LCV. The compensation determiner 730 may compare the display brightness LUM_D with the target brightness TL to determine that a period between the zero stress value SV0 and the second stress value SV2 (the period during which the display brightness LUM_D is greater than the target brightness TL) is the miscompensation period MCP, and may determine that a period after the second stress value SV2 (the period during which the display brightness LUM_D is less than or equal to the target brightness TL) is the compensation period CP.

[0097] The compensation determiner 730 may not perform the degradation compensation operation during the miscompensation period MCP. Fig. 9B As shown in , the compensation determiner 730 may output the data signal DATA to the driving controller 200 without compensating for the display brightness LUM_D.

[0098] The compensation determiner 730 may perform a degradation compensation operation during the compensation period CP. Fig. 9B As shown in , the compensation determiner 730 may compensate for the display brightness LUM_D according to the brightness compensation value LCV to output the data signal DATA to the driving controller 200 .

[0099] As described above, the degradation compensator 700 may perform a process similar to Fig. 9B The degradation compensation operation of the degradation curve G2' of the flexible display panel B.

[0100] Fig. 10A and Fig. 10B It is shown by Figure 2 The degradation compensator 700 is relative to Figure 4C A graph showing the degradation compensation operation performed by the flexible display panel C.

[0101] refer to Figures 1 to 10B , the degradation compensator 700 may perform a degradation compensation operation with respect to the flexible display panel C.

[0102] The compensation value calculator 720 may calculate the brightness compensation value LCV based on the input image data IMG and the stress value SV by using a lookup table LUT. For example, the brightness compensation value LCV may be calculated as 0 nit at the zero stress value SV0, the brightness compensation value LCV may be calculated as 2 nit at the first stress value SV1, and the brightness compensation value LCV may be calculated as 15 nit at the fourth stress value SV4.

[0103] The compensation determiner 730 may receive the display luminance LUM_D and the luminance compensation value LCV and may compare the display luminance LUM_D with the target luminance TL to determine that the period after the zero stress value SV0 (the period in which the display luminance LUM_D is less than or equal to the target luminance TL) is the compensation period CP.

[0104] The compensation determiner 730 may perform a degradation compensation operation during the compensation period CP. Fig. 10B As shown in , the compensation determiner 730 may compensate for the display brightness LUM_D according to the brightness compensation value LCV to output the data signal DATA to the driving controller 200 .

[0105] As described above, the foldable display device 10 can sense the display brightness LUM_D as the brightness of the test image using the camera module CM disposed in the first display area DA1 of the flexible display panel 100, and may not perform the degradation compensation operation in the miscompensation period MCP (which is a period in which the display brightness LUM_D is greater than the target brightness TL), and may perform the degradation compensation operation in the compensation period CP (which is a period in which the display brightness LUM_D is less than or equal to the target brightness TL). Therefore, the foldable display device 10 can selectively perform the degradation compensation operation in the compensation period CP to improve the display quality of the foldable display device 10.

[0106] As described above, the degradation compensator 700 may perform a process similar to Fig. 10B The degradation compensation operation of the degradation curve G3' of the flexible display panel C is shown.

[0107] Fig.11 is a flowchart illustrating a method for compensating for degradation of the flexible display panel 100 according to one embodiment of the present disclosure.

[0108] refer to Figures 1 to 11, a method for compensating for degradation of a flexible display panel 100 according to an embodiment of the present disclosure includes the following steps: sensing a display brightness LUM_D, the display brightness LUM_D being the brightness of a test image displayed on the flexible display panel 100 including a folding line FL, a first display area DA1 being disposed on a first side of the folding line FL, and a second display area DA2 being disposed on a second side of the folding line FL (S100); and when the display brightness LUM_D is less than or equal to a target brightness TL, performing a degradation compensation operation of compensating the display brightness LUM_D according to a brightness compensation value LCV, and when the display brightness LUM_D is greater than the target brightness TL, not performing the degradation compensation operation (S200).

[0109] Fig.11 The method for compensating for degradation of the flexible display panel 100 is substantially the same as the method for compensating for degradation of the flexible display panel 100. Figure 2 The method of degradation of the foldable display device 10 is the same. Therefore, substantially the same description will be omitted.

[0110] Therefore, according to the method for compensating for degradation of the flexible display panel 100, the display brightness LUM_D as the brightness of the test image can be sensed using an optical module disposed in the first display area DA1 of the flexible display panel 100, and the degradation compensation operation may not be performed in the miscompensation period MCP (which is a period in which the display brightness LUM_D is greater than the target brightness TL), and the degradation compensation operation may be performed in the compensation period CP (which is a period in which the display brightness LUM_D is less than or equal to the target brightness TL). Therefore, the method for compensating for degradation of the flexible display panel 100 can selectively perform the degradation compensation operation in the compensation period CP, thereby improving the display quality of the foldable display device 10.

[0111] Fig.12 is a perspective view showing a foldable display device 10 according to an embodiment. Fig.13 It is shown Fig.12 1 is a block diagram of a foldable display device 10.

[0112] refer to Fig.12 and Fig.13 The foldable display device 10 may include a flexible display panel 100 and a display panel driver. The display panel driver may include a driving controller 200, a gate driver 300, a data driver 500, an emission driver 600, and a degradation compensator 700. The foldable display device 10 may further include an optical module. In an embodiment, the optical module may be an optical fingerprint sensor OFS.

[0113] The optical fingerprint sensor OFS may be disposed in the second display area DA2. Typically, the optical fingerprint sensor OFS may sense the user's fingerprint by receiving light reflected from the user's finger. The optical fingerprint sensor OFS may also be used as an illumination sensor. In this case, the optical fingerprint sensor OFS may sense external brightness. In the present invention, the flexible display panel 100 may display a test image in the first display area DA1, and the optical fingerprint sensor OFS may sense the display brightness LUM_D as the brightness of the test image.

[0114] In addition to the optical module is an optical fingerprint sensor OFS, Fig.12 and Fig.13 The foldable display device 10 and Figure 1 and Figure 2 The foldable display device 10 is substantially the same. That is, only the method of sensing the external brightness is different, and FIG. 4A to FIG. 11 The operation of the degradation compensator 700 described in is substantially the same. Therefore, redundant explanations therefor will be omitted.

[0115] Fig.14 is a block diagram showing the electronic device 1000 .

[0116] refer to Fig.14 , the electronic device 1000 may include a processor 1010, a memory device 1020, a storage device 1030, an input / output (I / O) device 1040, a power supply 1050, and a display device 1060. The display device 1060 may be Figure 1 The foldable display device 10. In addition, the electronic device 1000 may further include a plurality of ports for communicating with a graphics card, a sound card, a memory card, a universal serial bus (USB) device, other electronic devices, and the like.

[0117] In an embodiment, if Fig.13 As shown in , the electronic device 1000 may be implemented as a smart phone. However, the electronic device 1000 is not limited thereto. For example, the electronic device 1000 may be implemented as a mobile phone, a video phone, a smart tablet, a smart watch, a tablet PC, a car navigation system, a computer monitor, a laptop computer, a head mounted display (HMD) device, etc.

[0118] The processor 1010 may perform various computing functions. The processor 1010 may be a microprocessor, a central processing unit (CPU), an application processor (AP), etc. The processor 1010 may be connected to other components via an address bus, a control bus, a data bus, etc. In addition, the processor 1010 may be connected to an expansion bus such as a peripheral component interconnect (PCI) bus.

[0119] The memory device 1020 may store data used for the operation of the electronic device 1000. For example, the memory device 1020 may include at least one nonvolatile memory device and / or at least one volatile memory device, the nonvolatile memory device being, for example, an erasable programmable read-only memory (EPROM) device, an electrically erasable programmable read-only memory (EEPROM) device, a flash memory device, a phase change random access memory (PRAM) device, a resistive random access memory (RRAM) device, a nano-floating gate memory (NFGM) device, a polymer random access memory (PoRAM) device, a magnetic random access memory (MRAM) device, a ferroelectric random access memory (FRAM) device, etc., and the volatile memory device being, for example, a dynamic random access memory (DRAM) device, a static random access memory (SRAM) device, a mobile DRAM device, etc.

[0120] The storage device 1030 may include a solid state drive (SSD) device, a hard disk drive (HDD) device, a CD-ROM device, or the like.

[0121] I / O devices 1040 may include input devices such as a keyboard, a keypad, a mouse device, a touch pad, a touch screen, etc. and output devices such as a printer, a speaker, etc. In some embodiments, I / O devices 1040 may include a display device 1060 .

[0122] The power supply 1050 may provide power for the operation of the electronic device 1000 .

[0123] Display device 1060 may be connected to other components via a bus or other communication links.

[0124] The inventive concept can be applied to any display device and any electronic device including a touch panel. For example, the inventive concept can be applied to mobile phones, smart phones, tablet computers, digital televisions (TVs), 3D TVs, personal computers (PCs), home appliances, laptop computers, personal digital assistants (PDAs), portable multimedia players (PMPs), digital cameras, music players, portable game consoles, navigation devices, etc.

[0125] The foregoing is an illustration of the inventive concept and should not be construed as limiting the inventive concept. Although some embodiments of the inventive concept have been described, it will be readily understood by those skilled in the art that many modifications are possible in the embodiments without substantially departing from the novel teachings and advantages of the inventive concept. Therefore, all such modifications are intended to be included within the scope of the inventive concept as defined in the claims. In the claims, the device-plus-function clause is intended to cover the structure described herein that performs the function, and not only structural equivalents, but also equivalent structures. Therefore, it should be understood that the foregoing is an illustration of the inventive concept and should not be construed as being limited to the specific embodiments disclosed, and modifications to the disclosed embodiments and other embodiments are intended to be included within the scope of the appended claims. The inventive concept is defined by the appended claims and the equivalents of the claims to be included therein.

Claims

1. A foldable display device, comprising: A flexible display panel, comprising: a folding line, a first display area arranged on a first side of the folding line, and a second display area arranged on a second side of the folding line for displaying a test image; an optical module disposed in the first display area to perform a sensing operation of sensing display brightness, the display brightness being brightness of the test image; and The degradation compensator is configured to perform a degradation compensation operation of compensating the display brightness according to a brightness compensation value when the display brightness is less than or equal to a target brightness, and not perform the degradation compensation operation when the display brightness is greater than the target brightness.

2. The foldable display device according to claim 1, wherein: The optical module performs the sensing operation when a folding angle, which is an angle between the first display area and the second display area, is less than or equal to a reference angle.

3. The foldable display device according to claim 2, wherein: The reference angle includes 0 degrees.

4. The foldable display device according to claim 2, wherein: A sensing area is determined by the folding angle, the sensing area being an area of ​​the test image sensed by the optical module.

5. The foldable display device according to claim 4, wherein: The sensing area is smaller than an area of ​​the flexible display panel.

6. The foldable display device according to claim 5, wherein: When the folding angle is 0 degrees, the sensing area is equal to the area of ​​the optical module.

7. The foldable display device according to claim 5, wherein: The degradation compensation operation is performed on the entire flexible display panel based on the sensing area.

8. The foldable display device according to claim 7, wherein: The sensing area has a brightness compensation value equal to a brightness compensation value of the entire flexible display panel.

9. The foldable display device according to claim 1, wherein: When the sensing operation is performed, the test image is displayed in the second display area.

10. The foldable display device according to claim 1, wherein: The degradation compensator includes a lookup table including brightness compensation values ​​corresponding to stress values ​​of the flexible display panel.

11. The foldable display device according to claim 10, wherein: The degradation compensator uses the lookup table to compensate the display brightness according to the brightness compensation value.

12. The foldable display device according to claim 1, wherein: The degradation compensator comprises: a memory device configured to store a stress value of the flexible display panel; a compensation value calculator configured to calculate the brightness compensation value based on the stress value; and A compensation determiner is configured to determine whether to perform the degradation compensation operation by comparing the display brightness with the target brightness, and when performing the degradation compensation operation, compensate the display brightness according to the brightness compensation value.

13. The foldable display device according to claim 1, wherein: The optical module includes a camera module or an optical fingerprint sensor.

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