Display apparatus and control method thereof

Abstract

The present invention relates to a display apparatus and a control method thereof. The display apparatus determines a gray scale of a first pixel based on video data, determines whether the first pixel is in a first degradation mode or a second degradation mode after the first degradation mode based on a driving history of the first pixel, in a case where it is determined that the first pixel is in the first degradation mode, refers to first adjustment information for the first degradation mode and determines a data signal to be supplied to the first pixel based on the gray scale and the driving history of the first pixel, and in a case where it is determined that the first pixel is in the second degradation mode, refers to second adjustment information for the second degradation mode and determines the data signal to be supplied to the first pixel based on the gray scale and the driving history of the first pixel.

Description

Technical Field

[0001] This disclosure relates to a display device and a method for controlling the display device. Background Technology

[0002] Organic light-emitting diode (OLED) devices are current-driven light-emitting devices, thus eliminating the need for backlighting. Furthermore, OLED devices offer advantages such as low power consumption, wide viewing angles, and high contrast; they are expected to contribute significantly to the development of flat panel display devices.

[0003] OLED devices degrade over time (driving time). Degraded OLED devices cannot emit light with the same brightness using the same driving current as before. Furthermore, unless a higher driving voltage is applied, the same driving current cannot be obtained as before. OLED devices require increased driving voltage and decreased brightness over driving time.

[0004] There are several external compensation techniques to compensate for the degradation of OLED element brightness. These techniques utilize the results of assessing the degradation of the monitored OLED elements and the cumulative data on the luminance of each individual OLED element. Summary of the Invention

[0005] The characteristic variations of OLED devices are non-uniform; this variation is not easily monitored and compensated for accurately. Specifically, the degradation (characteristic variation) of OLED devices generally falls into two modes: an initial degradation mode that occurs in the initial period after driving begins, and a stable degradation mode that occurs in the period following the initial period. The initial degradation mode exhibits more complex characteristic variations than the stable degradation mode.

[0006] The initial degradation mode is more likely to depend on manufacturing deviations; the characteristic changes in the initial degradation mode differ between display panels. Therefore, it is not possible to determine the characteristic changes in the initial degradation mode and the transition point from the initial degradation mode to the stable degradation mode in the same way for different display panels.

[0007] Therefore, identifying whether an OLED element is in an initial degradation mode during the initial driving period or a stable degradation mode in subsequent periods is crucial for improving the accuracy of external compensation. This also applies to display devices using light-emitting elements that differ from OLED elements.

[0008] One aspect of this disclosure is a display device, comprising: a display area including a plurality of pixels, the display area being configured to display an image based on video data from an external source; and a control circuit configured to control the plurality of pixels. Each of the plurality of pixels includes a light-emitting element and pixel circuitry. The control circuit is configured to: determine a grayscale level of a first pixel based on video data; determine, based on a driving history of the first pixel, whether the first pixel is in a first degradation mode or a second degradation mode following the first degradation mode; if the first pixel is determined to be in the first degradation mode, determine a data signal to be supplied to the first pixel by referring to first adjustment information for the first degradation mode and based on the grayscale level and driving history of the first pixel; and if the first pixel is determined to be in the second degradation mode, determine the data signal to be supplied to the first pixel by referring to second adjustment information for the second degradation mode, which is different from the first adjustment information, and based on the grayscale level and driving history of the first pixel.

[0009] One aspect of this disclosure is to improve the display quality of display devices.

[0010] It should be understood that the general description above and the detailed description below are exemplary and explanatory, and do not limit this disclosure. Attached Figure Description

[0011] Figure 1 An example configuration of an OLED display device is illustrated schematically;

[0012] Figure 2A The layout of the control lines on the TFT substrate is schematically shown;

[0013] Figure 2B The diagram schematically illustrates the anode power line pattern and the layout of the cathode electrodes on an insulating substrate.

[0014] Figure 3A An example configuration of pixel circuitry in the normal display area is shown;

[0015] Figure 3B An example configuration of pixel circuits in the first and second degradation evaluation regions is shown;

[0016] Figure 4A An example is shown showing the relationship between high-temperature aging time and relative brightness for OLED elements used in red subpixels;

[0017] Figure 4B An example is shown showing the relationship between high-temperature aging time and relative brightness for OLED elements used in green subpixels;

[0018] Figure 4CAn example is shown showing the relationship between high-temperature aging time and relative brightness for OLED elements used in blue subpixels;

[0019] Figure 5A An example is shown showing the relationship between the high-temperature aging time and the relative driving voltage for an OLED element used for a red subpixel;

[0020] Figure 5B An example is shown showing the relationship between the high-temperature aging time and the relative driving voltage of an OLED element used for a green subpixel;

[0021] Figure 5C An example is shown showing the relationship between the high-temperature aging time and the relative driving voltage of an OLED element used for a blue subpixel;

[0022] Figure 6A An example is shown showing the relationship between the relative driving voltage and relative brightness of an OLED element used for a red subpixel;

[0023] Figure 6B An example of the relationship between relative driving voltage and relative brightness for OLED elements used in green subpixels is shown;

[0024] Figure 6C An example of the relationship between relative driving voltage and relative brightness for OLED elements used in blue subpixels is shown;

[0025] Figure 7 This is a flowchart illustrating an aging test.

[0026] Figure 8 This is a plan view showing an example configuration of a motherboard undergoing aging tests;

[0027] Figure 9 This is a schematic diagram illustrating a technique for supplying a higher drive voltage by supplying a higher power supply voltage than in normal operation in response to a data signal that is the same as the data signal in normal operation during aging tests.

[0028] Figure 10 An example of the layout of the anode power line pattern and the cathode electrode on a TFT substrate is shown schematically.

[0029] Figure 11 The logical configuration of the OLED display device is illustrated schematically.

[0030] Figure 12 This is a flowchart illustrating a normal display operation after the product leaves the factory.

[0031] Figure 13 An example of the drive voltage under constant current drive, measured from the second degradation assessment region, is provided;

[0032] Figure 14 An example of a light-shielding structure is shown;

[0033] Figure 15 Another example of a light-shielding structure is shown;

[0034] Figure 16 The cross-sectional structure of the TFT substrate, driving TFT and OLED elements, and packaging structure unit is schematically shown.

[0035] Figure 17 This is a plan view showing an example of a light-shielding film pattern and a touch electrode pattern formed on a touchscreen; and

[0036] Figure 18 An example configuration of an OLED display device is shown, in which the first degradation assessment area is kept in a non-emissive state. Detailed Implementation

[0037] Embodiments of this disclosure will now be described with reference to the accompanying drawings. It should be noted that these embodiments are merely examples of implementing this disclosure and do not limit the technical scope of this disclosure.

[0038] In the following description, a pixel is the smallest unit in a display area and is an element used to emit monochromatic light. It is also called a subpixel. A group of pixels of different colors (e.g., red, green, and blue) constitutes an element used to display a point of mixed color. This element can be called a master pixel.

[0039] In the following description, a pixel may include a light-emitting element and pixel circuitry for controlling that light-emitting element. For clarity, when it is necessary to distinguish between elements for emitting monochromatic light and elements for emitting mixed-color light, the former is referred to as a sub-pixel and the latter as a main pixel. The features of this specification apply to monochrome display devices whose display area consists of monochromatic pixels.

[0040] The characteristics of OLED devices change non-uniformly; this change is not easy to monitor and compensate for precisely. Specifically, the degradation (characteristic change) of OLED devices generally falls into two modes: an initial degradation mode that occurs during the initial period of operation and a stable degradation mode that occurs in the period after the initial period. The initial degradation mode exhibits more complex changes than the stable degradation mode.

[0041] The initial degradation mode is more likely to depend on production variations; the characteristic changes within the initial degradation mode differ between display panels. For different display panels, it is difficult to uniformly determine the characteristic changes within the initial degradation mode and the transition point from the initial degradation mode to the stable degradation mode.

[0042] Therefore, identifying whether the OLED element is in an initial degradation mode during the initial period or a stable degradation mode in a period after the initial period is important for improving compensation accuracy. This also applies to display devices that use light-emitting elements different from OLED elements.

[0043] The display device in the embodiments of this specification determines whether pixel degradation is in an initial degradation mode or a stable degradation mode based on the pixel's driving history. The display device uses a method suitable for selecting either an initial degradation mode or a stable degradation mode based on the determination result to determine the data signal to be supplied to the pixel based on the grayscale level (emissivity level) determined from video data. Therefore, emissivity control suitable for the degradation mode is performed for each pixel.

[0044] Display device configuration

[0045] This describes an example configuration of a display device. In the examples described below, the light-emitting elements of the pixels are current-driven elements, such as organic light-emitting diode (OLED) elements. Reference Figure 1 This description outlines the overall configuration of the display device in the embodiments. For clarity, the elements in the accompanying drawings may be exaggerated in size or shape. An organic light-emitting diode (OLED) display device is described below as an example of a display device.

[0046] Figure 1 An example configuration of an OLED display device 10 is schematically illustrated. The OLED display device 10 includes a thin-film transistor (TFT) substrate 100 and a structural packaging unit 250 for encapsulating OLED elements. The TFT substrate 100 includes OLED elements (light-emitting elements). The TFT substrate 100 includes an insulating substrate on which the OLED elements are fabricated. The insulating substrate may be a flexible polyimide substrate or a rigid glass substrate.

[0047] The pixel array region 125 of the TFT substrate 100 includes multiple OLED elements and multiple pixel circuits for controlling the light emission of the OLED elements. The cathode electrode region 114 extends to a region further outward than the pixel array region 125; control circuitry is disposed around the periphery of the cathode electrode region 114. The control circuitry includes a scan driver 131, a light emission driver 132, an aging test circuit 133, a driver IC 134, and a demultiplexer 136. The driver IC 134 is connected to an external device via a flexible printed circuit (FPC) 135.

[0048] Scan driver 131 drives scan lines on TFT substrate 100 and further drives selection lines for pre-shipment aging tests and post-shipment degradation assessments of dummy pixels described later. Light emission driver 132 drives light emission control lines to control pixel emission. Aging test circuit 133 supplies data signals for pre-shipment aging tests to pixel array region 125. Aging test circuit 133 may include electrostatic discharge protection circuitry (not shown).

[0049] The driver IC 134 is mounted with, for example, an anisotropic conductive film (ACF). The driver IC 134 is connected to an external device via a flexible printed circuit 135.

[0050] The driver IC 134 drives and controls the scan driver 131, the light-emitting driver 132, and the aging test circuit 133 on the substrate. The driver IC 134 provides power signals, including timing signals, and control signals to the scan driver 131 and the light-emitting driver 132.

[0051] The driver IC 134 also generates a data signal from the video data received from the outside and supplies the data signal along with the power supply potential to the pixel array region 125. The data signal is provided to the pixel array region 125 through the demultiplexer 136.

[0052] Driver IC 134 provides power and data signals to demultiplexer 136. Demultiplexer 136 outputs the output of one pin of driver IC 134 sequentially to d data lines (d is an integer greater than 1). Demultiplexer 136 changes the output data lines used for the data signal from driver IC 134 d times in each scan period to drive d times the number of data lines as the output pin of driver IC 134.

[0053] Cabling layout

[0054] The following describes an example of the wiring layout of the OLED display device 10. Figure 2A The layout of the control lines on the TFT substrate 100 is schematically shown. Figure 2B The layout of the anode power line pattern and the cathode electrode on the insulating substrate 202 is schematically shown.

[0055] exist Figure 2A In the configuration example, pixel array region 125 includes a normal display region 200 located in the middle, two second degradation evaluation regions 212 sandwiching the normal display region 200 in the middle, and two first degradation evaluation regions (test regions) 211 sandwiching these regions 200 and 212 in the middle. The first degradation evaluation region 211, the second degradation evaluation region 212, the normal display region 200, another second degradation evaluation region 212, and another first degradation evaluation region 211 are arranged in this order from... Figure 2A The settings are from left to right. Pixels in the normal display area 200 can be referred to as display pixels, and pixels in the first degradation evaluation area 211 can be referred to as test pixels.

[0056] The normal display area 200 displays images based on video data received from an external source. The first degradation assessment area 211 is used for aging tests performed before the OLED display device 10 leaves the factory and is not used for displaying images based on video data received from an external source. As described later, the first degradation assessment area 211 degrades faster due to accelerated aging. The aging test assesses the progression of OLED element degradation caused by accelerated aging and generates adjustment data based on the assessment results. The adjustment data is consulted to adjust the data signals to be supplied to the pixel circuitry in the normal display area 200.

[0057] The second degradation evaluation area 212 is used to evaluate pixel degradation after the OLED display device 10 leaves the factory, and is not used to display images. The second degradation evaluation area 212 is controlled to be under the same conditions as the normal display area 200. Specifically, the same power supply voltage is supplied to the second degradation evaluation area 212 as to the normal display area 200, and the upper and lower limits of the data signal used in the second degradation evaluation area 212 are the same as the upper and lower limits of the data signal used in the normal display area 100.

[0058] Figure 2A In the example, the pixel layout in the normal display area 200 is a strip arrangement. Specifically, each subpixel column extending along the Y-axis (vertical axis) consists of subpixels of the same color. Subpixels include OLED elements and their pixel circuitry. Each subpixel row extending along the X-axis (horizontal axis) consists of a cyclical arrangement of red, green, and blue subpixels.

[0059] Two second degradation evaluation regions 212 are located on both sides of the normal display region 200 and adjacent to the normal display region 200. The pixel layout here is the same as that in the normal display region 200, which is a strip arrangement. Figure 2A Each second degradation evaluation region 212 includes a red dummy subpixel column, a green dummy subpixel column, and a blue dummy subpixel column, but each second degradation evaluation region 212 may include multiple dummy subpixel columns of each color for more accurate degradation compensation.

[0060] The two first degradation evaluation regions 211 are configured to be adjacent to the outer ends of the second degradation evaluation region 212, respectively. The pixel layout here is the same as that in the normal display region 200, which is a strip arrangement. Figure 2AEach first degradation assessment region 211 includes a red dummy subpixel column, a green dummy subpixel column, and a blue dummy subpixel column, but each first degradation assessment region 211 may include multiple dummy subpixel columns of each color for more accurate degradation compensation.

[0061] The number of pixel rows (sub-pixel rows) in the first degradation evaluation area 211 and the second degradation evaluation area 212 is equal to the number of pixel rows (sub-pixel rows) in the normal display area 200. In another example, the number of pixel rows in the first degradation evaluation area 211 and the second degradation evaluation area 212 may be less than the number of pixel rows in the normal display area 200. In this case, the number of pixels connected to each control line is different between the scan line 106 and the light emission control line 107. This means that the load on the control lines is different. Therefore, it is necessary to set the output buffer's output control signal capability and the voltage level of the control signal so that the accuracy of the degradation evaluation is not affected by the load difference between the control lines, which may cause control signal delay.

[0062] The pixel layout in degradation evaluation areas 211 and 212 can differ from the pixel layout in normal display area 200. Degradation evaluation areas 211 and 212, as well as normal display area 200, can use any pixel layout.

[0063] Multiple scan lines 106 extend from scan driver 131 along the X-axis. Multiple light emission control lines 107 extend from light emission driver 132 along the X-axis. Figure 2A In the figure, as an example, one scan line and one emission control line are assigned reference numerals 106 and 107, respectively. Figure 2A In the configuration example, scan line 106 sends selection signals not only to the normal display area 200 but also to the degradation evaluation areas 211 and 212. Illumination control line 107 sends illumination control signals not only to the normal display area 200 but also to the degradation evaluation areas 211 and 212.

[0064] Multiple data lines 105 are configured to extend along the Y-axis and be arranged side-by-side along the X-axis within the pixel array region 125. Figure 2A In the example, one of the data lines is designated as 105. Data line 105 is connected to aging test circuit 133 and demultiplexer 136. Data line 105 is disposed in normal display area 200 and degradation evaluation areas 211 and 212; each data line sends a data signal to the pixel circuit connected thereto.

[0065] Data signals are supplied from the aging test circuit 133 to all pixel circuits in the pre-shipment aging test. After shipment, data signals for the normal display area 200 and the second degradation evaluation area 212 are supplied from the driver IC 134, and data signals for the first degradation evaluation area 211 are supplied from either the driver IC 134 or the aging test circuit 133.

[0066] Although Figure 2A Although not shown in the diagram, lines for evaluating the degradation of dummy pixels in degradation evaluation regions 211 and 212 are provided on the insulating substrate 202. Specifically, selection lines and sensing lines are provided; the selection lines are used to select dummy pixels whose degradation is to be evaluated, and the sensing lines are used to measure the voltage of the OLED element in the selected dummy pixel.

[0067] The selection line can be controlled by scan driver 131 or a driver circuit different from scan driver 131 and light-emitting driver 132. The sensing line for the first degradation evaluation region 211 can be connected to aging test circuit 133, and the signal from the first degradation evaluation region 211 is supplied to an external device through aging test circuit 133. The sensing line for the second degradation evaluation region 212 can be connected to driver IC 134 or aging test circuit 133, and the signal from the second degradation evaluation region 212 is supplied to driver IC 134 directly or through aging test circuit 133.

[0068] During pre-shipment aging testing, the driver IC 134 is not yet mounted on the TFT substrate 100. Therefore, an external device, separate from the TFT substrate 100, controls the scan driver 131, the light-emitting driver 132, and the aging test circuit 133 to perform aging tests on the first degradation evaluation area 211. Dashed ellipses 204 and 206 indicate the cut areas of the control lines connected to the external device. The control lines extend to the end of the insulating substrate 202. As described later, multiple TFT substrates 100 are cut from a motherboard. The TFT substrates 100 are subjected to aging tests before being cut from the motherboard.

[0069] The video data comprises consecutive frames, and the OLED display device 10 displays images corresponding to each frame. Driver IC 134 sends control signals to scan driver 131, light-emitting driver 132, and aging test circuit 133. Driver IC 134 controls the timing of the scan signal (selection pulse) from scan driver 131 and the light-emitting control signal from light-emitting driver 132 based on external video data.

[0070] Driver IC 134 supplies data signals for sub-pixels in the normal display area 200 to demultiplexer 136. Driver IC 134 determines the data signal for each sub-pixel in the normal display area 200. The data signal for a sub-pixel is determined from the intensity level of one or more sub-pixels of video data received from the outside (one frame). Demultiplexer 136 sequentially outputs one output of driver IC 134 to N data lines 105 (N is an integer greater than 1) during the scan period.

[0071] The driver IC 134 also supplies data signals for dummy sub-pixels in the second degradation evaluation region 212. The driver IC 134 supplies the data signals for the dummy sub-pixels to the second degradation evaluation region 212 via data lines 105 associated with the dummy sub-pixels. The dummy sub-pixels to which the data signals transmitted by a single data line 105 are to be supplied are selected by different scan lines 106. Furthermore, the driver IC 134 sends control signals for degradation evaluation to the second degradation evaluation region 212 and receives measurement signals from the second degradation evaluation region 212. For example, the driver IC 134 uses a selection signal from the scan driver 131 to select the dummy pixel circuit to be evaluated and uses a sensing line to measure the voltage of the OLED element in the selected dummy pixel.

[0072] Driver IC 134 can supply data signals for dummy sub-pixels in the first degradation evaluation area 211 after leaving the factory. Driver IC 134 supplies data signals for dummy sub-pixels to the first degradation evaluation area 211 via associated data lines 105. The dummy sub-pixels to which the data signals transmitted by a single data line 105 are to be supplied are selected by different scan lines 106. Driver IC 134 sends control signals for degradation evaluation to the first degradation evaluation area 211 and receives measurement signals from the first degradation evaluation area 211. For example, driver IC 134 uses a selection signal from scan driver 131 to select the dummy pixel circuit to be evaluated and uses a sensing line to measure the voltage of the OLED element in the selected dummy pixel. Details of the degradation evaluation will be described later.

[0073] The dashed line 207 represents a fold line of the TFT substrate 100. The insulating substrate 202 is, for example, a flexible substrate made of polyimide. The area including the driver IC 134 is folded backward. Therefore, the overall size of the TFT substrate 100 can be reduced. The insulating substrate 200 can be a rigid substrate.

[0074] Figure 2B The anode power line pattern and cathode electrode layout on the TFT substrate 100 are schematically shown. Figure 2BAs shown, the TFT substrate 100 includes an anode power line pattern 115. The anode power line pattern 115 supplies anode power potential to the pixel circuits in the normal display area 200, the first degradation evaluation area 211, and the second degradation evaluation area 212.

[0075] The driver IC 134 outputs an anode power potential to the anode power line pattern 115 and a cathode power potential to the cathode electrode 114. The anode power line pattern 115 has a mesh shape; it includes a contour portion defining the outer ends of the pattern, multiple X-axis portions, and multiple Y-axis portions. The X-axis portions are configured to extend along the X-axis in a region inward of the contour portion and overlap each other along the Y-axis. The Y-axis portions are configured to extend along the Y-axis in a region inward of the contour portion and are arranged side-by-side along the X-axis. The X-axis portions and Y-axis portions extend from one side of the contour portion to the opposite side. The anode power line pattern 115 can have different shapes.

[0076] The cathode electrode 114 has a sheet-like shape that completely covers the normal display area 200, the first degradation evaluation area 211, and the second degradation evaluation area 212. The cathode electrode of each sub-pixel in these areas is part of the sheet-like cathode electrode 114.

[0077] The dashed ellipse 206 represents the cut-off region of the power lines used to supply the anode and cathode power potentials from the outside. The power lines extend to the end of the insulating substrate 202. As described above, an aging test is performed before mounting the driver IC 134 and cutting the TFT substrate 100 from the motherboard. Therefore, the anode and cathode power potentials are supplied to the TFT substrate 100 from an external device via the power lines.

[0078] Pixel circuit configuration

[0079] Multiple pixel circuits are fabricated on the TFT substrate 100 to control the current supplied to the anode electrode of the sub-pixel. Figure 3A An example configuration of pixel circuitry in a normal display area 200 is shown. Each pixel circuit includes a driving transistor T1, a selection transistor T2, a light-emitting transistor T3, and a storage capacitor C1. The pixel circuitry controls the emission of light from the OLED element E1. The transistors are TFTs.

[0080] Select transistor T2 is a switch used to select a sub-pixel. Select transistor T2 is a p-channel TFT, with its gate terminal connected to scan line 106. Its source terminal is connected to data line 105. Its drain terminal is connected to the gate terminal of drive transistor T1.

[0081] Driving transistor T1 is a transistor (driving TFT) used to drive OLED element E1. Driving transistor T1 is a p-channel TFT, and its gate terminal is connected to the drain terminal of selection transistor T2. The source terminal of driving transistor T1 is connected to power line 108 for transmitting the anode power supply potential VDD. The drain terminal of driving transistor T1 is connected to the source terminal of light-emitting transistor T3. Storage capacitor C1 is disposed between the gate terminal and the source terminal of driving transistor T1.

[0082] Light-emitting transistor T3 is a switch used to control the supply / stop of drive current to OLED element E1. Light-emitting transistor T3 is a p-channel TFT, and its gate terminal is connected to the light-emitting control line 107. The source terminal of light-emitting transistor T3 is connected to the drain terminal of drive transistor T1. The drain terminal of light-emitting transistor T3 is connected to OLED element E1. The cathode of OLED element E1 is supplied with a cathode power supply potential VSS.

[0083] The pixel circuit includes a threshold voltage compensation circuit 103. The threshold voltage compensation circuit 103 compensates for variations in the threshold voltage of the driving transistor T1. The threshold voltage compensation circuit 103 includes multiple thin-film transistors. Various known circuit configurations exist for the threshold voltage compensation circuit 103; a desired circuit configuration can be employed.

[0084] Next, the operation of the pixel circuit is described. Scan driver 131 outputs a selection pulse to scan line 106 to turn on selection transistor T2. The data voltage supplied from driver IC 134 via data line 105 is adjusted by threshold voltage compensation circuit 103 according to the threshold voltage of driving transistor T1 and stored in storage capacitor C1. Storage capacitor C1 holds the stored voltage for the entire duration of a frame. The conductance of driving transistor T1 changes analogously according to the stored voltage, causing driving transistor T1 to supply a forward bias current corresponding to the grayscale level to OLED element E1.

[0085] Light-emitting transistor T3 is located on the drive current supply path. Light-emitting driver 132 outputs a control signal to light-emitting control line 107 to control the on / off state of light-emitting transistor T3. When light-emitting transistor T3 is on, drive current is supplied to OLED element E1. When light-emitting transistor T3 is off, this supply stops. The light-emitting period (duty cycle) within a frame can be controlled by controlling the on / off state of transistor T3.

[0086] Figure 3B An example configuration of pixel circuits in the first degradation evaluation region 211 and the second degradation evaluation region 212 is shown. (Compared to...) Figure 3A Compared to the pixel circuits in the normal display area 200, Figure 3BThe pixel circuit in the image has a configuration that includes an additional switching transistor T5. Switching transistor T5 is used to evaluate the degradation of OLED element E1; it is connected to sensing line 102 and the anode of OLED element E1.

[0087] Specifically, one of the source and drain of the switching transistor T5 is connected to the node between the anode of the OLED element E1 and the transistor T3, while the other of the source and drain is connected to the sensing line 102. The gate of the switching transistor T5 is connected to the selection line 104 used to transmit the selection signal SEL.

[0088] Transistor T5 is turned on / off by the selection signal SEL, and the sensing line 102 transmits the degradation measurement signal SENSE. To evaluate the degradation of OLED element E1, a predetermined data signal is supplied to the storage capacitor C1, switching transistor T5 on, and the voltage of OLED element E1 (degradation measurement signal SENSE) is measured using the sensing line 102. Alternatively, during the period when transistor T3 is not conducting, current is supplied from the driver IC 134 through the sensing line 102, and the voltage of OLED element E1 is measured for evaluation.

[0089] As described above, the pixel circuits in the normal display area 200 and the pixel circuits of the dummy pixels in the degradation evaluation areas 211 and 212 are identical in the portion used to control the light emission of the OLED element E1. The pixel circuits of the dummy pixels include, in addition to the circuit configuration of the pixel circuits in the normal display area 200, circuitry for degradation evaluation. Therefore, the degradation state of the pixel circuits in the normal display area 200 can be inferred more accurately.

[0090] Figure 3A and Figure 3B The pixel circuit shown is an example; pixel circuits can have other circuit configurations. Although Figure 3A and Figure 3B The pixel circuits in the image use p-channel TFTs, but they can also use n-channel TFTs.

[0091] Changes in the characteristics of OLED components

[0092] The following describes the time-varying degradation of OLED components. Figures 4A to 4C Examples of the relationship between high-temperature aging time and relative luminance for OLED elements used in red, green, and blue subpixels are shown, illustrating the time-varying relative luminance of OLED elements driven and controlled by pixel circuitry. In each graph, the horizontal axis represents aging time, and the vertical axis represents relative luminance. Aging time is the elapsed time since the OLED element began emitting light. Relative luminance is defined with an initial value of 100.

[0093] exist Figures 4A to 4C In each graph, the change in relative brightness at gray level 255 is represented by a solid line, and the change in relative brightness at gray level 186 is represented by a dashed line. Gray level 255 is the highest gray level, corresponding to maximum brightness (100%). Gray level 186 is an intermediate level, corresponding to 50% brightness. The gray level corresponds to the level of the data signal supplied to the pixel circuitry.

[0094] like Figures 4A to 4C As shown, for any color and grayscale level, relative brightness increases at the start of emission and then decreases. The time period showing the temporal change in relative brightness can be divided into two segments: the initial degradation period T01 since the start of emission and the stable degradation period following the initial degradation period T01. The characteristic changes during the initial degradation period T01 can be referred to as the initial degradation mode, while the characteristic changes during the stable degradation period can be referred to as the stable degradation mode.

[0095] A stable degradation mode is one in which relative brightness decreases at a relatively constant rate. An initial degradation mode precedes the stable degradation mode. The initial degradation mode exhibits more complex changes in relative brightness than the stable degradation mode. Figures 4A to 4C The examples in the text demonstrate an initial increase and subsequent decrease in relative brightness. The point where relative brightness begins to change steadily can be identified as the transition point between the two degradation modes.

[0096] like Figures 4A to 4C As shown, relative brightness varies over time depending on the color of the subpixel. Furthermore, relative brightness varies over time depending on the gray level. For example, the length of the initial degradation period T01 varies depending on the color and further varies depending on the gray level of the same color. Compared to the relative brightness at gray level 255, the relative brightness at gray level 186 increases to a larger value during the initial degradation period T01 and decreases at a smaller rate during the stable degradation period. Note that... Figures 4A to 4C An example of relative brightness variation over time is provided; the actual variation over time will vary depending on the panel.

[0097] Next, the relationship between the driving voltage and aging time of an OLED element is described. The driving voltage of an OLED element is the voltage between the anode and cathode of the OLED element. Figures 5A to 5C Examples of the relationship between the high-temperature aging time and the relative driving voltage of LED elements for red, green, and blue subpixels are shown, illustrating the time variation of the relative driving voltage of OLED elements driven and controlled by pixel circuitry. Figures 5A to 5C From providing Figures 4A to 4C The same OLED elements were obtained.

[0098] exist Figures 5A to 5C In each graph, the horizontal axis represents aging time, and the vertical axis represents the driving voltage of the OLED element. Aging time is the elapsed time since the OLED element began emitting light. The relative driving voltage is defined as an initial value of 100. Figures 5A to 5C In the figure, the initial degradation period is indicated by the reference numeral T01.

[0099] like Figures 5A to 5C As shown, the stable degradation mode exhibits a relatively constant increase in the driving voltage, while the initial degradation mode precedes the stable degradation mode. The initial degradation mode exhibits more complex changes than the stable degradation mode. Figures 5A to 5C In the example, the initial degradation mode initially exhibits a high growth rate relative to the drive voltage, followed by a lower growth rate. The point where the relative drive voltage begins to change at a constant rate can be identified as the transition point between the two degradation modes.

[0100] like Figures 5A to 5C As shown, the relative driving voltage varies with time depending on the color of the sub-pixel. Furthermore, the relative driving voltage varies with different gray levels. For example, the length of the initial degradation period T01 varies depending on the color and also varies with the gray levels of the same color. Compared to the relative driving voltage at gray level 186, the relative driving voltage at gray level 255 increases to a larger value during the initial degradation period T01 and further increases at a higher rate during the stable degradation period. Note that... Figures 5A to 5C An example of the time variation relative to the drive voltage is provided; the actual time variation varies depending on the panel.

[0101] The relative drive current of OLED elements exhibits a specific change with respect to aging time. Drive current is the current flowing through an OLED element at a constant voltage. Therefore, the degradation of an OLED element can be inferred by measuring the drive current, rather than the drive voltage.

[0102] Figures 6A to 6C The diagram schematically illustrates the relationship between the relative driving voltage and relative brightness of an OLED element. Figures 6A to 6C In each graph, the horizontal axis represents the relative driving voltage, and the vertical axis represents the relative brightness. Figures 6A to 6C In the figure, the initial degradation period is indicated by the reference numeral T01.

[0103] Figures 6A to 6C An example is shown showing the relationship between the relative driving voltage and relative brightness for OLED elements used for red, green, and blue subpixels. Figure 6A The data in the middle is from Figure 4A and Figure 5A The data was obtained from [the source]. Figure 6B The data in the middle is from Figure 4B and Figure 5B The data was obtained from [the source]. Figure 6C The data in the middle is from Figure 4C and Figure 5C The data was obtained from [the data source]. Emission control was based on the degradation state of the OLED element.

[0104] like Figures 4A to 4C As shown, the relative brightness changes with aging time. The change in relative brightness can vary depending on the color and gray level (data signal level) of the subpixel and also on the TFT substrate 100. In a TFT substrate 100, subpixels of the same color exhibit substantially the same change in relative brightness with respect to aging time at each gray level.

[0105] The embodiments described in this specification perform a degradation assessment on the first degradation assessment region 211 during the manufacturing process prior to shipment. More specifically, the degradation assessment measures the change in relative brightness of sub-pixels of each color illuminated at different gray levels in the first degradation assessment region 211 relative to aging time.

[0106] The designer based on Figures 4A to 4C The results of degradation assessments at multiple different gray levels, illustrated in the example, create adjustment information representing the relationship between the driving history (driving) of a subpixel and the adjustment amount of the data signal. Designers can refer to this information together. Figures 5A to 5C The measurement results of the changes in the driving voltage shown are used to determine a more appropriate adjustment amount. The adjustment information is included in the OLED display device 10. The OLED display device 10 records the driving history of each sub-pixel in the normal display area 200 and adjusts the data signal based on the driving history and adjustment information.

[0107] Below, two methods for adjusting the data signal are mainly described. One method refers to determining the adjustment amount of the data signal for the sub-pixels in the normal display area 200 by referring to the results of the post-factory degradation assessment of the second degradation assessment area 212 and adjustment information. The other method does not refer to the results of the degradation assessment of the second degradation assessment area 212 when determining the adjustment amount of the data signal for the sub-pixels in the normal display area 200. The OLED display device 10 using the latter method does not need to include the second degradation assessment area 212.

[0108] First, an adjustment method is described that does not refer to the results of the degradation assessment of the second degradation assessment region 212. The designer can determine the relationship between the degradation state of each color sub-pixel and the change in relative brightness based on the assessment results of the first degradation assessment region 211, and further determine the adjustment amount for the data signal based on the change in relative brightness. For example, the data signal can be adjusted by adjusting the grayscale level.

[0109] The degradation state of a subpixel is calculated based on its driving history. The degradation state can be represented using standard gray levels and driving time (operation time). See reference... Figures 4A to 6C If a sub-pixel emits light at a fixed gray level, then that fixed gray level is a standard gray level, and the emission time is the driving time. In the aging test, the predetermined fixed gray level is the standard gray level, and the aging time is the driving time.

[0110] The gray levels (data signals) of the sub-pixels used in the normal display area 200 are not fixed, but change instantaneously. Degradation states can be normalized over the driving history of sub-pixels that are driven differently. The degradation state of a sub-pixel is calculated based on its driving history. The driving history represents the temporal variation of the gray levels assigned to the sub-pixel.

[0111] A simple method is to determine the standard gray level as the time-averaged gray level from the driving history. Driving time is the total time for supplying gray-level-based data signals to sub-pixels. Driving time can be the total operating time of the device. The methods for calculating the standard gray level and driving time are not limited to these; an appropriate method can be determined based on the design. Degradation conditions can be represented using one or more variables that represent feature values ​​different from the combination of standard gray levels and driving time. For example, temperature information can be included.

[0112] Adjustment information, representing the relationship between the driving history and the adjustment amount used for the data signal, is included in the OLED display device 10. As described above, the adjustment information is configured based on the evaluation results of the first degradation evaluation region 211. The OLED display device 10 uses the adjustment information to adjust the data signal for the sub-pixels of each color in the normal display region 200.

[0113] The adjustment information enables the determination of the adjustment amount for the data signal used for that sub-pixel based on the sub-pixel's driving history and the gray level (intensity level in the image) specified for that sub-pixel in the next video frame to be displayed. For example, the driving history may include the total emission time for each past gray level. The OLED display device 10 calculates the degradation state based on the driving history, for example, using a function included in the adjustment information. Furthermore, the OLED display device 10 refers to the adjustment information and determines the adjustment amount for the data signal, for example, the adjustment amount for the intensity level in the image, based on the determined degradation state and the intensity level in the image.

[0114] The OLED display device 10 stores adjustment information for each color. The OLED display device 10 records the driving history of each sub-pixel and determines the adjustment amount for the data signal based on the adjustment information, the driving history, and the intensity level in the image.

[0115] For reference Figures 4A to 4CThe OLED elements degrade in significantly different ways between an initial degradation mode (initial degradation period) and a stable degradation mode (stable degradation period). Therefore, for the light emission control of the normal display area 200, it is important for the OLED display device 10 to identify the degradation mode of each sub-pixel and adjust the data signal using a method applicable to that degradation mode.

[0116] In the embodiments described in this specification, the OLED display device 10 determines the degradation state of each sub-pixel based on the driving history of the sub-pixels. During the period from when the sub-pixel starts operating after leaving the factory until the degradation state reaches a predetermined state, the sub-pixel is determined to be in an initial degradation period (initial degradation mode). When the degradation state reaches the predetermined state, the sub-pixel is determined to have entered a stable degradation period (stable degradation mode).

[0117] When the degradation state is represented by standard gray levels and driving time, a threshold for the driving time can be assigned to each gray level. When the driving time of a sub-pixel reaches the threshold assigned to its standard gray level, the degradation of the sub-pixel is determined to change from the initial degradation mode to a stable degradation mode.

[0118] The OLED display device 10 adjusts the data signal used for the sub-pixels by referring to adjustment information prepared for each color. The adjustment information includes adjustment information prepared for the initial degradation period and adjustment information prepared for the stable degradation period. (See reference...) Figures 4A to 4C The relative brightness varies in a complex manner during the initial degradation period and decreases in a substantially constant manner during the stable degradation period.

[0119] In embodiments of this specification, the adjustment information for the initial degradation period is a lookup table providing the relationship between degradation state and adjustment amount. This configuration enables adjustments suitable for complex variations in relative brightness. The adjustment information for the stabilizing degradation period can be a predefined function. This configuration saves memory area required for adjustments. The adjustment information for the stabilizing degradation period can include a different lookup table than the one used for the initial degradation period.

[0120] When a subpixel is in the initial degradation period, the OLED display device 10 refers to a lookup table to determine the adjustment amount. Once the subpixel enters the stable degradation mode, the OLED display device 10 switches the light emission control for the subpixel from the light emission control used for the initial degradation mode to the light emission control used for the stable degradation mode. In the embodiments of this specification, the light emission control for the stable degradation mode considers the state of the subpixel when it enters the stable degradation mode as the nominal initial state used to control its light emission. The OLED display device 10 uses only the driving history during the stable degradation period, without referring to the driving history prior to entering the stable degradation period. For example, the adjustment amount is determined using a function or lookup table that takes the driving time, average gray level, and intensity level in the image as inputs since the start of the stable degradation mode.

[0121] As described above, the second degradation evaluation region 212 can be excluded when the adjustment of the data signal used for the normal display region 200 is not based on the post-factory evaluation results of the dummy pixel. Furthermore, if it is possible for manufacturing purposes, the first degradation evaluation region 211 can be cut out from the TFT substrate 100 after the degradation evaluation of the first degradation evaluation region 211 is completed.

[0122] Another method for controlling the light emission of the normal display area 200 is described. This method references not only the results of a pre-shipment degradation assessment of the first degradation assessment area 211, but also the results of a post-shipment degradation assessment of the second degradation assessment area 212. This configuration allows for more appropriate light emission control of the normal display area 200. The degradation assessment measures the current-voltage characteristics of the OLED elements in the second degradation assessment area 212. Details of the light emission control and degradation assessment for the second degradation assessment area 212 will be described later.

[0123] For reference Figures 5A to 5C As described, in each of the initial degradation mode and the stable degradation mode, the relative driving voltage of the OLED element changes characteristically with aging time. Furthermore, as referenced... Figures 6A to 6C The relative brightness of each color exhibits a specific relationship with the driving voltage in each TFT substrate 100. Therefore, by comparing the measured driving voltage in the first degradation evaluation region 211 with the measured driving voltage in the second degradation evaluation region 212, more appropriate degradation compensation in the normal display region 200 can be obtained.

[0124] Measurements from the second degradation assessment region 212 can be utilized in several ways. An example of this utilization is inferring whether a subpixel in the normal display region 200 has transitioned from an initial degradation mode to a stable degradation mode. Another example of this utilization is calculating the amount of adjustment used for the data signal during a stable degradation period.

[0125] Another example of this utilization is calculating the adjustment amount used for the data signal during the initial degradation period. One or more of these utilizations can be applied to the OLED display device 10. A detailed method for using measurement results from the second degradation evaluation region 212 will be described later.

[0126] Pre-shipment aging test

[0127] The following describes a pre-shipment aging test used to evaluate degradation in the first degradation assessment area 211. Information for degradation compensation in the normal display area 200 is generated based on the results of this degradation assessment and set in the OLED display device 10.

[0128] Aging tests can be performed under accelerated degradation conditions to reduce the time required for degradation assessment. Examples of accelerated degradation conditions can include high temperatures, high drive voltages for OLED elements, and high data signal levels for pixel circuits.

[0129] In the embodiments described in this specification, the aging test divides sub-pixels of the same color in the first degradation evaluation region 211 on each TFT substrate into multiple groups and supplies data signals of different levels to each group. Different data signal levels under accelerated conditions correspond to different gray levels under normal operating conditions.

[0130] The aging test measures the brightness and drive voltage of each color sub-pixel group, for which different levels of data signals are provided. The brightness of each sub-pixel group can be measured using a point sensor that is moved to sense the light point or using a region sensor, and the change in brightness of each sub-pixel group is measured. Measuring brightness with a point sensor allows groups other than the one being measured to remain in a non-emitting state.

[0131] The driving voltage of an OLED element is measured through its pixel circuitry. For example... Figure 3B As shown, the pixel circuit in the first degradation evaluation region 211 includes a switching transistor T5 for evaluating the degradation of the OLED element E1. The switching transistor T5 is kept off during light emission control to accelerate the degradation of the OLED element E1. During degradation evaluation of the OLED element E1, the switching transistor T5 is kept on.

[0132] Aging control writes a predetermined data signal to the pixel circuit selected by scan line 106 via data line 105 and keeps switching transistor T3 on to illuminate OLED element E1. Degradation evaluation selects the pixel circuit to be evaluated via selection line 104 and keeps switching transistor T5 on. In the pixel circuits connected to sensing line 102, all pixel circuits except the one to be evaluated are supplied with selection signal SEL to keep their switching transistor T5 off.

[0133] Sensing line 102 transmits a degradation measurement signal for each sub-pixel. The degradation measurement signal represents the anode potential of the OLED element E1. The cathode potential is fixed. Therefore, the degradation measurement signal represents the driving voltage of the OLED element E1. Instead of the driving voltage under constant current, the driving current under low voltage can be measured.

[0134] The aging test measures the time-varying changes in brightness and driving voltage for each combination of data signal level and color. The aging test calculates the average brightness value and average driving voltage of the sub-pixels in each sub-pixel group. Changes in these averages represent the changes in brightness and driving voltage for each combination of data signal level and color.

[0135] The aging test continues until all subpixels exhibit a stable degradation pattern. The data obtained from the aging test is used to determine the relationship between the degradation level of each color subpixel and the amount of adjustment to the data signal in both the initial degradation pattern and the stable degradation pattern.

[0136] The aging test was conducted by an external testing system. Figure 7 This is a flowchart of an example of an aging test. The test system writes multiple levels of data signals to the first degradation evaluation area 211 under degradation acceleration conditions (conditions that cause sub-pixels to emit light at a brighter level than the highest level in normal operation) and evaluates the degradation state (S11).

[0137] The testing system continues aging tests until it determines that all sub-pixel groups provided with data signals of different levels have transitioned from the initial degradation period to the stable degradation period (S12). The testing system averages the measurement results according to the data signal levels and accumulates the data used to infer the degradation state (S13).

[0138] As described above, the measurement data represents the changes in brightness and current-voltage characteristics of each color subpixel at each data signal level. Therefore, initial degradation modes or stable degradation modes can be appropriately identified. Furthermore, the degradation rate after entering a stable degradation mode can be monitored using the data signal level, and the monitoring results can be fed back into the degradation calculation formula during normal display operation.

[0139] Figure 8 This is a plan view showing an example configuration of a motherboard 400 undergoing aging tests. Before the driver IC 134 is installed, the motherboard 400 includes multiple TFT substrates 100. Figure 8 In the example, a TFT substrate before cutting is labeled 100. Figure 8In the configuration example, the motherboard 400 includes multiple pads 411 for aging tests in an area outside the TFT substrate 100. The pads 411 are positioned along the ends of the motherboard 400, and transmission lines 431 extend from the pads 411 to the TFT substrate 100. Figure 8 In the figure, as an example, a pad and a transmission line are assigned reference numerals 411 and 431, respectively. Figure 8 Only some pads 411 and transmission lines 431 are shown.

[0140] The test system (not shown) contacts multiple pins of its connected devices to pads 411 and supplies power potential and control signals to first degradation evaluation areas 211 of multiple TFT substrates 100. Transmission line 431 is connected to... Figure 2A and Figure 2B The transmission lines in the elliptical regions 204, 205, or 206 enclosed by the dashed lines.

[0141] Specifically, the test system supplies control signals for the scan driver 131, the light-emitting driver 132, and the aging test circuit 133, as well as data signals for the data lines, through the control pad 411, and further supplies the anode power potential, the cathode power potential, and the power potential for the scan driver 131, the light-emitting driver 132, and the aging test circuit 133 through the power pad 411.

[0142] After the aging test is completed, each TFT substrate 100 is cut from the motherboard 400. Figure 8 In the diagram, some of the multiple horizontal and vertical cutting lines are assigned reference numerals. Specifically, cutting line 453 is... Figure 8 The motherboard 400 extends horizontally, and the cutting line 451 is on it. Figure 8 It extends vertically on the motherboard 400.

[0143] Placing pads and transmission lines outside the TFT substrate area of ​​the motherboard 400 and supplying signals for aging tests to the TFT substrate 100 through them enables efficient aging tests and eliminates the need for pads on the TFT substrate.

[0144] Figure 9 This is a schematic diagram illustrating a technique for supplying a higher drive voltage than in normal operation in response to the same data signal as in normal operation during aging tests. For example, to perform accelerated aging tests on the first degradation evaluation area 211 at four times the brightness in normal display operation, a higher data signal voltage than usual is required, such as... Figure 9 As shown, by increasing the anode power supply potential, the sub-pixel can emit light four times brighter than usual in response to the normal data signal voltage.

[0145] Figure 9 This is a graph showing the light intensity characteristics under different anode power supply potentials. The X-axis represents the data signal voltage, and the Y-axis represents the brightness of the emitted light. Curve 501 shows the light intensity characteristics of the OLED element when the anode power supply potential VDD2 in the aging test is equal to the anode power supply potential VDD1 in normal operation. This characteristic is the same as that of the sub-pixels in the normal display area 200.

[0146] To achieve a white level, a data signal voltage Vd0 is supplied to the sub-pixels during normal operation, and a data signal voltage Vd1 is supplied to the sub-pixels in the first degradation evaluation region 211 during aging testing. In this example, the sub-pixels in the first degradation evaluation region 211 emit light at four times the brightness of the sub-pixels during normal operation.

[0147] Curve 502 represents the light intensity characteristics of the sub-pixels in the first degradation evaluation region 211 when the anode power supply potential VDD2 in the first degradation evaluation region 211 is higher than the anode power supply potential VDD1 in normal operation. By selecting a specific value for the anode power supply potential VDD2, in response to the same data signal voltage Vd0 in normal operation, the brightness of the sub-pixels in the first degradation evaluation region 211 reaches 400%. In other words, the sub-pixels in the first degradation evaluation region 211 can achieve four times the brightness under the same voltage range (from lowest to highest brightness) in normal operation.

[0148] Figure 10 An example of the layout of the anode power line pattern and the cathode electrode on the TFT substrate 100 is schematically shown. Figure 10 In the configuration example, the anode power line for the first degradation assessment area 211 is separated from the anode power line for the normal display area 200 and the second degradation assessment area 212.

[0149] For reference Figure 9 As described, this configuration allows the first degradation assessment region 211 to be supplied with a higher anodic power potential than other regions 200 and 212. By applying a higher driving voltage than that in normal operation between the anode and cathode electrodes of the OLED element E1 to allow a high current to flow through the OLED element E1, the time required for aging tests is reduced.

[0150] Figure 10 An example configuration includes pads for accelerated aging testing of the first degradation evaluation region 211 on the insulating substrate 202. This configuration allows for a reduction in the wiring area of ​​the motherboard; more TFT substrates can be mounted on the motherboard. Figure 8 As shown, the pads used for testing can be located outside the TFT substrate area.

[0151] like Figure 10As shown, the TFT substrate 100 includes a first anode power line pattern 551 and a second anode power line pattern 552. The first anode power line pattern 551 supplies anode power potential to the pixel circuits in the normal display area 200 and the second degradation evaluation area 212. The second anode power line pattern 552 supplies anode power potential to the pixel circuits in the first degradation evaluation area 211.

[0152] Multiple aging test pads are disposed on the insulating substrate 202, and some of them are labeled. The anode power pad 561 supplies a high anode power potential to the second anode power line pattern 552. Figure 10 In the example, the second anode power line pattern adjacent to the scan driver 131 and the second anode power line pattern adjacent to the light-emitting driver 132 are connected via the aging test circuit 133. If there is any space in the wiring layout of the insulating substrate 202, another anode power pad 561 can be placed near the second power line pattern adjacent to the light-emitting driver 132 to input the anode power potential to each second anode power line pattern.

[0153] Cathode power pad 562 supplies cathode potential to cathode electrode 114 from the outside. Pad 571 supplies control signals or power potential to light-emitting driver 132. Figure 10 As shown, multiple pads are provided for the scan driver 131, the light-emitting driver 132, and the aging test circuit 133.

[0154] The driver IC 134 outputs an anode power supply potential VDD1 to the first anode power line pattern 551, and the test system outputs an anode power supply potential VDD2 to the second anode power line pattern 552. The driver IC 134 and the test system output a cathode power supply potential VSS to the cathode electrode 114. The anode power supply potential VDD2 is higher than the anode power supply potential VDD1.

[0155] Illumination control for the normal display area

[0156] The following describes the post-shipment light emission control of the normal display area 200. The light emission control using adjustment information is described below, based on the results of a pre-shipment aging test on the first degradation assessment area 211 and further based on the results of a post-shipment degradation assessment of the second degradation assessment area 212. The results of the post-shipment degradation assessment of the first degradation assessment area 211 may also be used.

[0157] Figure 11The logic configuration of the OLED display device 10 is schematically illustrated. A grayscale signal controller 600, a data signal generator 621, a timing signal controller 622, a signal controller 631, a data signal output unit 632, and a degradation detector 633 may be included in the driver IC 134. Each logic functional unit may be implemented by hardware circuitry or a combination of hardware and software. The aging test circuit 133 is not required for operation after the product leaves the factory. Therefore, Figure 11 The aging test circuit 133 is not included. The aging test circuit 133 can be used to control or evaluate the degradation assessment area.

[0158] The grayscale signal controller 600 generates grayscale signals for each sub-pixel based on a video signal received from an external controller. The video signal consists of consecutive frames; a grayscale signal for each sub-pixel is generated from each frame. The grayscale signal specifies the grayscale level of the sub-pixel.

[0159] Data signal generator 621 generates data signals based on grayscale signals from grayscale signal controller 600. Data signals for displaying video frames are supplied to normal display area 200 via signal controller 631 and data signal output unit 632. Data signal generator 621 supplies data signals for degradation evaluation to first degradation evaluation area 211 and second degradation evaluation area 212. The data signal for first degradation evaluation area 211 is optional.

[0160] The degradation detector 633 detects the current / voltage values ​​from the second degradation assessment region 212. (The last sentence appears to be incomplete and possibly refers to a different process.) Figure 3B In the pixel circuit configuration, the degradation detector 633 detects the driving voltage value of each OLED element under constant current. The degradation detector 633 can detect the driving current value of each OLED element under constant voltage, and can also detect the current / voltage value from the first degradation evaluation region 211. The detection result of the degradation detector 633 is transmitted to the degradation determination unit 602 via the signal controller 632.

[0161] The timing signal controller 622 generates and outputs timing signals to control the timing of the scan signal, the light emission control signal, and the data signal. The timing signals are supplied to the signal controller 631, and then further supplied to the scan driver 131 and the light emission driver 132 through the signal controller 631.

[0162] The grayscale signal controller 600 adjusts the specified grayscale level in the video data according to the degradation state of the sub-pixels to generate an adjusted grayscale signal for the sub-pixels in the normal display area 200. The grayscale adjustment is based on adjustment information generated from the results of aging tests on the first degradation assessment area 211 and the results of post-factory degradation assessments on the second degradation assessment area 212. This configuration achieves more appropriate degradation compensation in the normal display area 200. This example is described below.

[0163] Another example involves performing a post-shipment degradation assessment on the second degradation assessment area 212 and the first degradation assessment area 211, and then compensating for degradation in the normal display area 200 based on the assessment results. Yet another example involves performing degradation compensation without performing a degradation assessment on the second degradation assessment area 212 and the first degradation assessment area 211.

[0164] The grayscale signal controller 600 includes a signal processing unit 601, the aforementioned degradation determination unit 602, an initial degradation mode grayscale signal generator 603, an initial degradation mode lookup table 604, a stable degradation mode grayscale signal generator 605, a stable degradation mode lookup table 606, and an adjustment information updater 607.

[0165] The signal processing unit 601 determines the grayscale level for each sub-pixel in each frame based on the video signal input from an external source. The degradation determination unit 602 records the driving history of each sub-pixel and determines its degradation mode based on the driving history of each sub-pixel. The degradation determination unit 602 also generates information needed to adjust the grayscale level. The degradation determination unit 602 determines whether each sub-pixel is in an initial degradation mode or a stable degradation mode based on the current / voltage values ​​measured from the second degradation evaluation region 212 and the driving history of the sub-pixel.

[0166] If the sub-pixel is in the initial degradation mode, the degradation determination unit 602 forwards the information about the frame's gray level and the degradation state required to adjust the gray level to the initial degradation mode gray level signal generator 603, and instructs the initial degradation mode gray level signal generator 603 to generate a gray level signal. If the sub-pixel is in the stable degradation mode, the degradation determination unit 602 forwards the information about the frame's gray level and the degradation state required to adjust the gray level to the stable degradation mode gray level signal generator 605, and instructs the stable degradation mode gray level signal generator 605 to generate a gray level signal.

[0167] The initial degradation mode grayscale signal generator 603 generates a grayscale signal for sub-pixels in the initial degradation mode. Based on the grayscale level received from the degradation determination unit 602, information about the degradation state, and the evaluation result of the second degradation evaluation region 212, the initial degradation mode grayscale signal generator 603 generates the grayscale signal by consulting the initial degradation mode lookup table 604. This grayscale signal specifies the grayscale level after degradation compensation.

[0168] The stable degradation mode grayscale signal generator 605 generates a grayscale signal for sub-pixels in a stable degradation mode. Based on the grayscale level received from the degradation determination unit 602, information about the degradation state, and the evaluation result of the second degradation evaluation region 212, the stable degradation mode grayscale signal generator 605 generates the grayscale signal by consulting the stable degradation mode lookup table 606, which specifies the grayscale level after degradation compensation.

[0169] Figure 12 This is a flowchart illustrating an example of normal display operation after factory release. Driver IC 134 applies a data signal representing a representative grayscale level under normal display conditions to the second degradation evaluation area 212 and evaluates the degradation state (S11). Data signal generator 621 supplies the second degradation evaluation area 212 with some or all of the data signals selected from the lowest to the highest level to be supplied to the normal display area 200. The grayscale data signal selected for aging tests on the first degradation evaluation area 211 can be supplied to the second degradation evaluation area 212.

[0170] For example, the data signal generator 621 divides the sub-pixels in the second degradation evaluation region 212 into multiple groups and supplies data signals for the same gray level to the sub-pixels in the same group. The gray level of the sub-pixels in the same group is fixed. At least some different groups are supplied with data signals of different levels.

[0171] In one example, each second degradation evaluation region 212 includes a group to which a data signal for a grayscale level shared between the two second degradation evaluation regions 212 will be supplied. The data signal generator 621 supplies a data signal for a fixed grayscale level to each sub-pixel in the second degradation evaluation region 212 during the same time period as the driving period (operation period) of the normal display region 200. A statistical value (e.g., average value) of the values ​​measured from sub-pixels of the same color at the same grayscale level can be used as the determining value for that color sub-pixel at that grayscale level.

[0172] The data signal generator 621 can also supply a data signal to the first degradation evaluation region 211. For example, the data signal generator 621 supplies a data signal to the sub-pixel for the same gray level as the data signal supplied during the aging test of the first degradation evaluation region 211. The data signal generator 621 or the signal processing unit 601 can adjust the data signal according to the characteristics of the OLED display device 10 independently of the initial degradation mode gray level signal generator 603 and the stable degradation mode gray level signal generator 605.

[0173] The degradation detector 633 sends the measurement results of the current-voltage characteristics of each sub-pixel in the second degradation evaluation region 212 to the degradation determination unit 602. Assume that the degradation detector 633 measures the driving voltage of an OLED element driven by a constant current in this example. Figure 3A and Figure 3B As shown, the scan line 108 and the light emission control line 107, shared with the normal display area 200, are used to control the application of data signals to the second degradation evaluation area 212. The degradation detector 633 detects the driving voltage of the sub-pixel selected by the selection line 104. The measured value is sent to the degradation determination unit 602, for example, in each frame.

[0174] The degradation determination unit 602 records the driving history of the normal display area 200 and further records the measurement results from the second degradation evaluation area 212. If the first degradation evaluation area 211 also needs to be evaluated, the degradation determination unit 602 also records the measurement results from the first degradation evaluation area 211.

[0175] Next, the degradation determination unit 602 determines the degradation mode of each sub-pixel in the normal display area 200 (S12). For example, this determination can be performed in each frame or in a predetermined number of frames. In the embodiments of this specification, the degradation determination unit 602 determines the degradation mode of the sub-pixel based on the driving history of the sub-pixel and the measurement results from the second degradation evaluation area 212.

[0176] For example, the degradation determination unit 602 determines the standard gray level of a sub-pixel based on its driving history. As described above, the standard gray level is calculated based on the total emission time of each gray level in the driving history; for example, the standard gray level could be a time-averaged value of the gray levels. The standard gray level provides information about the degradation state of the sub-pixel. The degradation determination unit 602 determines the driving voltage of sub-pixels of the same color at the standard gray level based on measurements from the second degradation evaluation region 212. If no sub-pixel actually emits light at the standard gray level, the driving voltage can be estimated using a complementary function from values ​​measured from sub-pixels emitting light at other gray levels.

[0177] The degradation determination unit 602 stores determination reference information representing the relationship between the relative driving voltage and the degradation mode, which is obtained from aging tests of the first degradation evaluation region 211 at each gray level for each color. For example, storing information representing... Figures 5A to 5C The information shown relates the change in relative driving voltage to the transition point between degradation modes. When the relative driving voltage increases uniformly with driving time, the corresponding relative driving voltage for each standard grayscale level can be saved as information representing the transition point.

[0178] The degradation determination unit 602 determines, based on the determination reference information, whether the sub-pixel of interest has entered a stable degradation mode by analyzing the history of the relative driving voltage of sub-pixels of the same color as the sub-pixel of interest at the standard gray level in the second degradation evaluation region 212, and the relationship between the relative driving voltage of the sub-pixel of that color at the standard gray level and the degradation mode. The reference value of the relative driving voltage in the second degradation evaluation region 212 can be determined at the factory, or it can be a value measured for the first time after leaving the factory.

[0179] If the sub-pixel of interest remains in the initial degradation mode (S12: Yes), the initial degradation mode grayscale signal generator 603 adjusts the grayscale level according to the instruction from the degradation determination unit 602 (S13). The initial degradation mode grayscale signal generator 603 obtains information about color and grayscale level based on video frames, as well as information for adjusting the grayscale level, from the degradation determination unit 602. For example, the information for adjustment represents the relative driving voltage of the sub-pixel of that color in the second degradation evaluation region 212 at the standard grayscale level.

[0180] The initial degradation mode grayscale signal generator 603 determines the adjustment amount for the grayscale level acquired from the video frame by consulting the initial degradation mode lookup table 604 using the color of the subpixel, the standard grayscale level, and the current grayscale level. The initial degradation mode lookup table 604 can provide the adjustment amount in response to inputs of color, standard grayscale level, relative drive voltage, and current grayscale level.

[0181] As described above, the initial degradation mode grayscale signal generator 603 can determine the adjustment amount in the initial degradation mode (initial degradation period) without using the measurement results from the second degradation assessment region 212. Alternatively, the initial degradation mode grayscale signal generator 603 can maintain zero adjustment in the initial degradation mode.

[0182] If a sub-pixel has already entered a stable degradation mode (S12: No), the stable degradation mode grayscale signal generator 605 adjusts the grayscale level according to the instruction from the degradation determination unit 602 (S14). The stable degradation mode grayscale signal generator 605 obtains information about color and grayscale level based on video frames, as well as information for adjusting the grayscale level, from the degradation determination unit 602. For example, the information for adjustment includes the driving time and standard grayscale level after the sub-pixel enters the stable degradation mode. The driving time and standard grayscale level after entering the stable degradation mode are information about the degradation state. Defining the state at the start of the stable degradation mode as the initial state and using the initial state as a reference to adjust the grayscale level allows for adjustments more suitable for the stable degradation mode. The initial state can be defined as a state later than the start of the stable degradation mode, and information about the standard grayscale level can be excluded.

[0183] The stable degradation mode grayscale signal generator 605 adjusts the current grayscale level by consulting the stable degradation mode lookup table 606 using the drive time after entering the stable degradation mode and the standard grayscale level. The stable degradation mode lookup table 606 can provide adjustment amounts in response to the input of color, the drive time after entering the stable degradation mode, the standard grayscale level, and the current grayscale level.

[0184] The adjustment information updater 607 updates the stable degradation mode lookup table 606 based on measurement results from the second degradation assessment region 212. The update frequency can be each predetermined operating period of the normal display region 200. The adjustment information updater 607 obtains the measurement history of the second degradation assessment region 212 from the degradation determination unit 602. The measurement history of the second degradation assessment region 212 can be the change of the relative driving voltage for multiple gray levels relative to the driving time after entering the stable degradation mode. The multiple gray levels can be the gray levels actually used to drive the second degradation assessment region 212.

[0185] Figure 13 An example of the drive voltage under constant current drive, measured from the second degradation assessment region 212, is provided. Figure 13 Data at 15 (653), 63 (652), and 256 (651) gray levels were provided. Figure 13 In the diagram, dashed lines represent estimated values ​​based on aging test results. Each marker Φ represents a value measured from the second degradation assessment region 212. Each solid line represents a result obtained by adjusting the estimated value with the measured value. The reference value for the relative drive voltage is the value at the start of the stable degradation mode.

[0186] The adjustment information updater 607 uses measurements from the second degradation assessment region 212 to correct for the time variation of the relative driving voltage in the stable degradation mode estimated based on aging tests of the first degradation assessment region 211, and further updates the stable degradation mode lookup table 606 according to this correction. As a result, the gray level for the sub-pixel in the stable degradation mode is determined based on measurements from the second degradation assessment region 212. Adjusting the gray level based on the state of the sub-pixel with existing degradation progress allows for more accurate degradation compensation.

[0187] The example above updates the stable degradation mode lookup table 606 based on measurements from the second degradation evaluation region 212. Another example could use post-factory measurements from the first degradation evaluation region 211 together. These provide information about more degraded subpixels.

[0188] Another example is that the gray level can be adjusted using the same adjustment method as in the initial degradation mode, with the driving voltage at the start of the stable degradation mode defined as a reference value. Yet another example is that the gray level for sub-pixels in the initial degradation mode can be adjusted without referring to the measurement results from the second degradation evaluation region 212, and the gray level for sub-pixels in the stable degradation mode can be adjusted with reference to the measurement results from the second degradation evaluation region 212.

[0189] Light-shielding structure

[0190] The following describes a structure for blocking light from the second degradation evaluation area 212. As described above, the OLED display device 10 is powered on together with the normal display area 200 and the second degradation evaluation area 212 after leaving the factory. Since the normal display area 200 displays images based on video data, the OLED display device 10 includes a light-blocking structure for blocking light from the second degradation evaluation area 212 to prevent the displayed image from being affected. When the first degradation evaluation area 211 is powered on together with the normal display area 200, the light-blocking structure also blocks light from both the first degradation evaluation area 211 and the second degradation evaluation area 212.

[0191] Figure 14 An example of a light-shielding structure is shown. Figure 14 An example of the structure includes a light-shielding film 721 in a metal layer on the substrate of the touchscreen 333. In addition to the light-shielding film 721, the metal layer also includes electrodes or lines for detecting touches on the touchscreen 333. This effective structure allows light from the second degradation evaluation area 212 to be invisible to the user in front of the panel.

[0192] Figure 14The insulating substrate 202 of the TFT substrate 100 and the OLED element 300 on the insulating substrate 202 are schematically shown. A touchscreen 333 is disposed on the front side of the TFT substrate 100 (on the side of the TFT substrate closer to the user viewing the image) and may be included. Figure 1 The structure is encapsulated in unit 250 as shown.

[0193] The light-shielding film 721 is a light-blocking metallic film. In Figure 14 In the configuration example, when viewed from the front, the light-shielding film 721 covers not only the second degradation evaluation area 212 but also the first degradation evaluation area 211. If the first degradation evaluation area 211 does not emit light after leaving the factory, the light-shielding film 721 can be excluded from the area in front of the first degradation evaluation area 211.

[0194] Figure 15 Another example of a light-shielding structure is shown. Figure 15 The example structure uses a metal casing 820 to block light from the second degradation assessment area 212. This effective structure ensures that light from the second degradation assessment area 212 is not visible to the user in front of the panel.

[0195] The metal casing 820 houses the TFT substrate 100 and includes a frame-like bezel region 822 surrounding the outer edge of the front side of the TFT substrate 100 displaying the image. The back side of the insulating substrate 202 is adhered to the inner bottom surface of the metal casing 820 by an adhesive (buffer material) 824. The metal casing 820 has an opening 823 on its front side located inside the bezel region 822. The normal display area 200 is observed through the opening 823. The second degradation evaluation area 212 is covered by the bezel region 822.

[0196] When viewed from the front, Figure 15 In the configuration example, the border area 822 covers not only the second degradation evaluation area 212, but also the first degradation evaluation area 211. In the case that the first degradation evaluation area 211 does not emit light after leaving the factory, the first degradation evaluation area 211 can be exposed from the metal casing 820.

[0197] The second degradation assessment area 212 and the first degradation assessment area 211 can be covered by another light-shielding structure, such as a light-shielding film in the black resin layer of the TFT substrate 100 or a filter substrate (not shown). The housing can be made of another material (e.g., resin) with light-shielding properties. As described above, the light-shielding film 721 and a portion of the metal housing 820 are light-shielding areas.

[0198] Figure 16The diagram schematically illustrates the cross-sectional structure of the TFT substrate 100, the driving TFT and OLED elements, and the encapsulation unit 250. The insulating substrate is a flexible substrate, but it can also be a rigid substrate. In the following description, the definitions of top and bottom correspond to the top and bottom in the figure. The encapsulation unit 250 can be an encapsulation substrate.

[0199] The OLED display device includes a TFT substrate 100 and a structural packaging unit 250. The TFT substrate 100 includes a substrate 202 and pixel circuits (TFT array) and OLED elements fabricated on the substrate 202. The pixel circuits and OLED elements are disposed between the substrate 202 and the structural packaging unit 250.

[0200] Substrate 202 is a flexible substrate composed of multiple layers including an organic layer (e.g., a polyimide layer) and an inorganic layer (e.g., a silicon oxide layer or a silicon nitride layer). Pixel circuits (TFT arrays) and OLED elements are fabricated on substrate 202. The OLED element includes a lower electrode (e.g., an anode electrode 308), an upper electrode (e.g., a cathode electrode 302), and a multilayer organic light-emitting film 304. The multilayer organic light-emitting film 304 is located between the cathode electrode 302 and the anode electrode 308. Multiple anode electrodes 308 are disposed on the same plane (e.g., on a planarization film 321); one multilayer organic light-emitting film 304 is disposed above one anode electrode 308. Figure 16 In the example, the cathode electrode 302 of a sub-pixel is part of a continuous conductive film.

[0201] Figure 16 The diagram illustrates an example of a top-emitting pixel structure, which includes a top-emitting OLED element. The top-emitting pixel structure is configured such that a cathode electrode 302 shared by multiple pixels is disposed on the emitting side (the side to be observed, or the upper side in the figure). The cathode electrode 302 has a shape that completely covers the entire pixel array region 125. The top-emitting pixel structure is characterized in that the anode electrode 308 is light-reflective and the cathode electrode 302 is light-transmitting. Therefore, a configuration is achieved that transmits light from the multilayer organic light-emitting film 304 to the structural encapsulation unit 250.

[0202] Compared to bottom-emitting pixel structures configured to extract light directed toward the substrate 202, top-emitting pixel structures do not require a light-transmitting area within the pixel region to extract light. Therefore, top-emitting pixel structures offer high flexibility in pixel circuit layout. For example, the light-emitting area can be positioned above the pixel circuitry or lines.

[0203] The bottom-emitting pixel structure has a transparent anode electrode and a reflective cathode electrode to emit light outward through the substrate (from the side to be observed). If both the anode and cathode electrodes are made of a light-transmitting material, a transparent display device can be obtained. The flexible substrate structure disclosed herein is applicable to any of these types of OLED display devices, and further applicable to display devices including light-emitting elements other than OLEDs.

[0204] In a full-color OLED display, subpixels typically emit light in one of three colors: red, green, or blue. Red, green, and blue subpixels constitute a main pixel. Pixel circuitry, comprising multiple thin-film transistors, controls the light emission of its associated OLED element. An OLED element consists of an anode (lower electrode), an organic light-emitting film, and a cathode (upper electrode).

[0205] OLED display devices include multiple pixel circuits (TFT arrays). Each pixel circuit includes multiple switches formed between substrate 202 and anode electrode 308 to control the current supplied to anode electrode 308. Figure 16 The driving TFT in this example has a top-gate structure. Other TFTs also have a top-gate structure.

[0206] A polysilicon layer is disposed above the substrate 202. The polysilicon layer includes a channel 315 at the location where the gate electrode 314 will be formed later. The characteristics of the TFT are determined by the channel 315. At both ends of each channel 315, source / drain regions 316 and 317 are provided. The source / drain regions 316 and 317 are doped with a high concentration of impurities for electrical connection with the wiring layer above them.

[0207] A lightly doped drain (LDD) with a low concentration of impurities can be disposed between channel 315 and source / drain region 316 and between channel 315 and source / drain region 317. Figure 16 LDD is omitted to avoid complexity. A gate electrode 314 is disposed above the polysilicon layer, and a gate insulating film 323 is located between the polysilicon layer and the gate electrode 314. An interlayer insulating film 322 is disposed above the layer of the gate electrode 314.

[0208] Within the pixel array region 125, source / drain electrodes 310 and 312 are disposed above the interlayer insulating film 322. Each source / drain electrode 310 and each source / drain electrode 312 are connected to the source / drain regions 316 and 317 of the polysilicon layer through contact holes 311 and 313 disposed in the interlayer insulating film 322 and the gate insulating film 323.

[0209] An insulating organic planarization film 321 is disposed on the source / drain electrodes 310 and 312. An anode electrode 308 is disposed above the planarization film 321. Each anode electrode 308 is connected to the source / drain electrode 312 through a contact hole 309 in the planarization film 321. The TFT of the pixel circuit is formed below the anode electrode 308.

[0210] The anode electrode 308 may consist of an intermediate reflective metal layer and a transparent conductive layer sandwiching the reflective metal layer in between. An insulating pixel defining layer (PDL) 307 is disposed above the anode electrode 308 to separate the OLED element. The OLED element is formed in an opening 306 in the pixel defining layer 307.

[0211] A multilayer organic light-emitting film 304 is disposed above each anode electrode 308. The multilayer organic light-emitting film 304 is in contact with the pixel defining layer 307 at the opening 306 and its periphery. Each multilayer organic light-emitting film 304 is formed by depositing an organic light-emitting material of R, G, or B color on the anode electrode 308.

[0212] A multilayer organic light-emitting film 304 is formed by vapor-phase deposition of organic light-emitting materials in the region corresponding to the pixel using a metal mask. The multilayer organic light-emitting film 304, for example, consists of, from bottom to top, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer. The layered structure of the multilayer organic light-emitting film 304 is determined according to the design.

[0213] A cathode electrode 302 is disposed on a multilayer organic light-emitting film 304. The cathode electrode 302 is a transparent electrode. The cathode electrode 302 transmits a portion of the visible light from the multilayer organic light-emitting film 304. The cathode electrode 302 is formed by vapor deposition of a metal such as Al or Mg or their alloys. If the resistance of the cathode electrode 302 is too high to impair the uniformity of the emitted light, an additional auxiliary electrode layer can be formed using a material suitable for transparent electrodes (such as ITO or IZO).

[0214] The stack of an anode electrode 308, a multilayer organic light-emitting film 304, and a cathode electrode 302 formed in the opening 306 of the pixel limiting layer 307 corresponds to an OLED element. A structural encapsulation unit 250 is disposed above and in direct contact with the cathode electrode 302. The structural encapsulation unit (thin-film encapsulation unit) 250, starting from the bottom, sequentially includes an inorganic insulating layer 301, an organic planarization film 331, and another inorganic insulating layer 332. The inorganic insulating layers 301 and 332 are a lower passivation layer and an upper passivation layer, respectively, used to improve reliability.

[0215] On the encapsulation unit 250, the touchscreen 333, the λ / 4 lens 334, the polarizer 335, and the resin-covered lens 336 are arranged in this order, facing upwards. The λ / 4 lens 334 and the polarizer 335 reduce the reflection of light from the outside. (Reference) Figure 16 The layered structure of the described OLED display device is an example; it can be omitted. Figure 16 One or more layers in, and can be added Figure 16 One or more layers not shown. Instead of depositing the touch screen on the TFT substrate 100, the touch screen manufactured in a process independent of the process used for the TFT substrate 100 can be properly aligned and bonded to the TFT substrate 100.

[0216] Figure 17 This is a plan view showing an example of the light-shielding film pattern and touch electrode pattern formed on the touch screen 333. Figure 17 The electrode pattern shown is for a projected capacitive touchscreen. Touchscreen 333 includes an X-touch electrode 771 and a Y-touch electrode 781. The X-touch electrodes extend along the X-axis and are stacked on top of each other along the Y-axis, while the Y-touch electrodes extend along the Y-axis and are arranged side-by-side along the X-axis. Figure 17 In the example, an X touch electrode and a Y touch electrode are assigned reference numerals 771 and 781, respectively.

[0217] Each X-touch electrode 771 consists of a rhomboid or triangular electrode piece 751 arranged along the X-axis and a rectangular connector region 753 for connecting the corners of adjacent electrode pieces 751. The connector region 753 is narrower than the electrode piece 751. The electrode piece 751 and the connector region 753 are made of a transparent conductor such as ITO. The X-touch electrode 771 is made of a continuous transparent conductor; its electrode piece 751 and connector region 753 are included in the same layer.

[0218] Each Y-touch electrode 781 consists of a rhomboid or triangular electrode piece 761 arranged along the Y-axis and a rectangular connector region 763 for connecting the corners of adjacent electrode pieces 761. The connector region 763 is narrower than the electrode piece 761. The electrode piece 761 is made of a transparent conductor such as ITO or IZO. Figure 17 In this example, electrode sheet 761 is included in the same layer as X-touch electrode 771. Connector region 763 is disposed on a layer above electrode sheet 761 and is made of a conductor (metal) with light-shielding properties. Connector region 763 may be made of Al or Mo.

[0219] The electrode pads 751 of the X-touch electrode 771 and 761 of the Y-touch electrode 781 are arranged in a matrix. A driver IC 134 or a detector circuit (not shown) detects the capacitance change between the X-touch electrode 771 and the Y-touch electrode 781 caused by a pointer (such as a finger or stylus) approaching the touchscreen 333 via lines 773 and 783. This operation locates the touch point.

[0220] When viewed in planar view, the connector region 763 of the Y-touch electrode 781 is positioned to intersect with the connector region 753 of the X-touch electrode 771. An insulating layer (not shown) is disposed between the layer of the connector region 763 and the layer of the X-touch electrode 771. An insulating film is inserted at the intersection between the connector regions 763 and 753 to maintain their electrical isolation.

[0221] The touchscreen 333 also includes a light-shielding film pattern composed of multiple light-shielding films 721. The light-shielding films 721 are disposed outside the touch detection area where touch electrodes 771 and 781 are located. As described above, the light-shielding films 721 are made of a light-shielding material; in Figure 17 In the example, the light-shielding film 721 is on the same layer as the connector area 763 of the Y-touch electrode 781, meaning that the light-shielding film 721 is made of a metal with light-shielding properties. Forming the light-shielding film 721 on the same layer as the light-shielding element of the touch screen 333 improves the efficiency of manufacturing the display device. Providing multiple light-shielding films 721 allows for a smaller size of each film, thereby minimizing any adverse effects on touch detection.

[0222] Figure 17 The configuration example includes columns of light-shielding films on both sides of the touch detection area. The number of columns and the number of light-shielding films in each column can be selected as desired. See reference... Figure 14 The light-shielding film 721 is arranged to cover the dummy sub-pixels, preventing light from the dummy sub-pixels from leaking to the user. The pattern of the light-shielding film 721 can also be determined as desired; for example, the patterns (number and shape) of the light-shielding films 721 on both sides of the touch detection area can be different. The number and shape of the light-shielding film used for the first degradation assessment area can differ from the number and shape of the light-shielding film used for the second degradation assessment area.

[0223] The light-shielding film 721 can be disposed on a separate layer of the touch screen 333, which includes light-shielding elements and is different from the touch electrodes, or on a different layer than the touch screen 333. Any sensing method can be selected for the touch screen 333; furthermore, the touch screen 333 is not required.

[0224] Post-shipment control for the first degradation assessment area

[0225] This section describes the post-shipment control of the first degradation assessment area 211 in the OLED display device 10. The configuration example of the OLED display device 10 in this section maintains the first degradation assessment area 211 in a non-emissive state during operation of the OLED display device 10. After shipment, no degradation assessment of the first degradation assessment area 211 is performed.

[0226] Figure 18 An example configuration of an OLED display device 10 is shown, in which the first degradation evaluation area 211 is kept in a non-emissive state. The aging test circuit 133 includes a data selection circuit 851. Each data selection circuit 851 supplies a data signal to all data lines used in the first degradation evaluation area 211, the value of which is equal to or lower than the absolute value of the data signal used for grayscale level 0 in the normal display area 200. As a result, all dummy pixels in the first degradation evaluation area 211 are kept in a non-emissive state. Therefore, a light-shielding structure for the first degradation evaluation area 211 becomes unnecessary.

[0227] As described above, embodiments of the present disclosure have been presented; however, the present disclosure is not limited to the foregoing embodiments. Those skilled in the art can readily modify, add to, or transform each element in the foregoing embodiments within the scope of the present disclosure. A portion of the configuration of one embodiment may be replaced by the configuration of another embodiment, or the configuration of one embodiment may be incorporated into the configuration of another embodiment.

Claims

1. A display device, comprising: A display area comprising a plurality of pixels is configured to display an image based on video data from an external source. A control circuit configured to control the plurality of pixels; A degradation evaluation area, comprising a plurality of dummy pixels disposed outside the display area, wherein each of the plurality of dummy pixels includes a light-emitting element and a pixel circuit; and The test area includes a plurality of test pixels disposed outside the display area, wherein each of the plurality of test pixels includes a light-emitting element and a pixel circuit, and the degradation evaluation area is located between the test area and the display area. Each of the plurality of pixels includes a light-emitting element and a pixel circuit. The control circuit is configured as follows: Based on the video data, determine the gray level of the first pixel; Based on the driving history of the first pixel, determine whether the first pixel is in a first degradation mode or a second degradation mode following the first degradation mode. If it is determined that the first pixel is in the first degradation mode, the data signal to be supplied to the first pixel is determined by referring to the first adjustment information for the first degradation mode and based on the gray level and driving history of the first pixel; and If it is determined that the first pixel is in the second degradation mode, the data signal to be supplied to the first pixel is determined by referring to second adjustment information for the second degradation mode, which is different from the first adjustment information, and based on the gray level of the first pixel, driving history, and measurement results of current-voltage characteristics from dummy pixels of the same color as the first pixel. The first adjustment information and the second adjustment information are based on measurement results from the plurality of test pixels regarding the relationship between driving history and the brightness of emission.

2. The display device according to claim 1, in, The control circuit is configured to determine, based on the driving history of the first pixel and measurements of current-voltage characteristics from a dummy pixel of the same color as the first pixel, whether the first pixel is in a first degradation mode or a second degradation mode following the first degradation mode.

3. The display device according to claim 1, wherein, The control circuit is configured as follows: If it is determined that the first pixel is in the second degradation mode, the state of the first pixel after entering the second degradation mode is determined to be the initial state of the first pixel in the second degradation mode. as well as Using the initial state as a reference and based on the grayscale level and driving history of the first pixel since the initial state, the data signal to be supplied to the first pixel is determined.

4. A display device, comprising: The display area includes a plurality of pixels, wherein each of the plurality of pixels includes a light-emitting element and a pixel circuit, and the display area is configured to display an image based on video data from an external source; A control circuit configured to control the plurality of pixels; A test area, comprising a plurality of test pixels disposed outside the display area, wherein each of the plurality of test pixels includes a light-emitting element and a pixel circuit; and The degradation assessment area includes a plurality of dummy pixels disposed outside the display area, wherein each of the plurality of dummy pixels includes a light-emitting element and a pixel circuit, and the degradation assessment area is located between the display area and the test area; The control circuit is configured as follows: Based on the video data, determine the gray level of the first pixel; Based on the measurement results of the relationship between driving history and brightness of emission from the multiple test pixels, the reference information is saved and determined. Based on the driving history of the first pixel, the determination reference information, and the measurement results of current-voltage characteristics from dummy pixels of the same color as the first pixel, it is determined whether the first pixel is in a first degradation mode or a second degradation mode following the first degradation mode. If it is determined that the first pixel is in the first degradation mode, the data signal to be supplied to the first pixel is determined by referring to the determination reference information for the first degradation mode and based on the gray level and driving history of the first pixel; and If it is determined that the first pixel is in the second degradation mode, the data signal to be supplied to the first pixel is determined by referring to the determination reference information for the second degradation mode, which is different from the determination reference information for the first degradation mode, and based on the gray level and driving history of the first pixel.

5. The display device according to claim 1 or 4, wherein, The control circuit is configured to keep the light-emitting elements in the test area in a non-light-emitting state during the period when the video data displays an image.

6. The display device according to claim 1 or 4, further comprising: A first line pattern is configured to supply a power potential to the anode of a light-emitting element in the display area; as well as A second line pattern, spaced apart from the first line pattern, is configured to supply a power potential to the anode of a light-emitting element in the test area.

7. A method for controlling a display device, The display device includes: A display area comprising a plurality of pixels is configured to display an image based on video data from an external source. A degradation evaluation area, comprising a plurality of dummy pixels disposed outside the display area, wherein each of the plurality of dummy pixels includes a light-emitting element and a pixel circuit; and The test area includes a plurality of test pixels disposed outside the display area, wherein each of the plurality of test pixels includes a light-emitting element and a pixel circuit, and the degradation evaluation area is located between the test area and the display area. Each of the plurality of pixels includes a light-emitting element and a pixel circuit. The method includes: Based on the video data, determine the gray level of the first pixel; Based on the driving history of the first pixel, determine whether the first pixel is in a first degradation mode or a second degradation mode following the first degradation mode. If it is determined that the first pixel is in the first degradation mode, the data signal to be supplied to the first pixel is determined based on the first adjustment information for the first degradation mode and the gray level and driving history of the first pixel; and If it is determined that the first pixel is in the second degradation mode, the data signal to be supplied to the first pixel is determined by using second adjustment information, which is different from the first adjustment information, for the second degradation mode, and based on the gray level of the first pixel, driving history, and measurement results of current-voltage characteristics from dummy pixels of the same color as the first pixel. The first adjustment information and the second adjustment information are based on measurement results from the plurality of test pixels regarding the relationship between driving history and the brightness of emission.

8. A method for controlling a display device, The display device includes: The display area includes a plurality of pixels, wherein each of the plurality of pixels includes a light-emitting element and a pixel circuit, and the display area is configured to display an image based on video data from an external source; A test area, comprising a plurality of test pixels disposed outside the display area, wherein each of the plurality of test pixels includes a light-emitting element and a pixel circuit; and The degradation evaluation area includes a plurality of dummy pixels disposed outside the display area, wherein each of the plurality of dummy pixels includes a light-emitting element and a pixel circuit, and the degradation evaluation area is located between the display area and the test area. The method includes: Based on the video data, determine the gray level of the first pixel; Based on the measurement results of the relationship between driving history and brightness of emission from the multiple test pixels, the reference information is saved and determined. Based on the driving history of the first pixel, the determination reference information, and the measurement results of current-voltage characteristics from dummy pixels of the same color as the first pixel, it is determined whether the first pixel is in a first degradation mode or a second degradation mode following the first degradation mode. If it is determined that the first pixel is in the first degradation mode, the data signal to be supplied to the first pixel is determined using the determination reference information for the first degradation mode and based on the gray level and driving history of the first pixel; and If it is determined that the first pixel is in the second degradation mode, the data signal to be supplied to the first pixel is determined by using the second degradation mode determination reference information, which is different from the determination reference information used for the first degradation mode, and based on the gray level and driving history of the first pixel.

Images