Display device and driving method thereof

Abstract

The invention provides a display device and a driving method thereof. The driving method comprises the following steps: timing from the beginning of a vertical blanking period of a frame of picture displayed by the display panel; when timing reaches a preset time point, controlling the power management chip to increase the power voltage of the pixels to be input into the display panel from a first voltage value to a preset voltage value; and after the vertical blanking period is finished, controlling the power supply management chip to restore the power supply voltage from the preset voltage value to the first voltage value. The display device comprises a display panel, a time schedule controller and a power management chip, the time schedule controller is electrically connected with the display panel, and the power management chip is electrically connected with the display panel and the time schedule controller. By dynamically adjusting the power supply voltage of the pixels of the display panel during the vertical blanking period, the display brightness attenuation caused by the leakage current of the low-temperature polycrystalline silicon thin film transistor can be effectively compensated, and the brightness uniformity of a display picture is improved.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a display device and a driving method thereof. Background Art

[0002] The application scope of OLED (Organic Light-Emitting Diode) display technology has expanded from mobile phones to laptops, monitors, and TVs. In gaming and e-sports application scenarios, OLED display panels need to support high refresh rate and variable refresh rate (VRR) functions to provide better display effects and user experience.

[0003] Currently, LTPS (Low Temperature Poly-Silicon) technology is widely used in OLED display panel products due to its excellent electron mobility characteristics. However, LTPS technology has the characteristic of large leakage current. During the display process, the leakage current of the LTPS thin-film transistor (TFT) will cause the data voltage stored in the pixel circuit to gradually decay over time, thereby causing the display brightness to decay. This brightness decay phenomenon manifests differently at different refresh rates: the lower the refresh rate, the longer the frame time, and the more obvious the brightness decay. Figure 1 As shown in FIG. 1 , at a refresh rate of 60 Hz, the brightness of the OLED display panel continues to decrease over time after the display data is written, as shown in FIG. 1 . Figure 2 As shown in the figure, at 60Hz and 120Hz refresh rates, due to different frame times, the brightness attenuation is different, resulting in different average brightness at the two refresh rates. The lower the refresh rate, the lower the average brightness. Therefore, in variable refresh rate mode, there will be a significant brightness difference between high refresh rate and low refresh rate, which is easy to produce flicker that can be perceived by the human eye, affecting the display quality and user experience.

[0004] Therefore, it is necessary to propose a new technical solution to solve the above technical problems. Summary of the invention

[0005] The purpose of the embodiments of the present application is to provide a display device and a driving method thereof, aiming to improve the brightness uniformity of a display panel using low-temperature polysilicon thin-film transistors when displaying images based on a variable refresh rate technology.

[0006] An embodiment of the present application provides a method for driving a display device, comprising: timing from the beginning of a vertical blanking period of a frame of an image displayed by a display panel of the display device; when the timing reaches a preset time point, controlling a power management chip of the display device to increase a power supply voltage of pixels to be input to the display panel from a first voltage value to a preset voltage value; and after the vertical blanking period ends, controlling the power management chip to restore the power supply voltage of pixels to be input to the display panel from the preset voltage value to the first voltage value.

[0007] In the above-mentioned driving method, before the timing starts at the beginning of the vertical blanking period of a frame of an image displayed by the display panel of the display device, the driving method also includes: receiving a variable refresh rate video source; and displaying a first image with a first refresh rate and a second image with a second refresh rate according to the variable refresh rate video source; wherein, when the first refresh rate is greater than the second refresh rate, the number of preset time points during the vertical blanking period of the first image is less than the number of preset time points during the vertical blanking period of the second image; when the first refresh rate is less than the second refresh rate, the number of preset time points during the vertical blanking period of the first image is greater than the number of preset time points during the vertical blanking period of the second image.

[0008] In the above-mentioned driving method, in the first picture, the preset voltage value is a second voltage value, and in the second picture, the preset voltage value is a third voltage value, and the second voltage value and the third voltage value are both greater than the first voltage value; when the first refresh rate is greater than the second refresh rate, the third voltage value is greater than the second voltage value; when the first refresh rate is less than the second refresh rate, the second voltage value is greater than the third voltage value.

[0009] In the above driving method, the vertical blanking period includes a plurality of the preset time points, and the time interval between two adjacent preset time points is in the range of 1 millisecond to 3 milliseconds.

[0010] In the above driving method, the vertical blanking period includes 1 to 6 preset time points.

[0011] An embodiment of the present application also provides a display device, comprising: a display panel; a timing controller electrically connected to the display panel; and a power management chip electrically connected to the display panel and the timing controller; wherein the timing controller is used to start timing from the beginning of a vertical blanking period of a frame displayed by the display panel of the display device, and to control the power management chip of the display device to increase the power supply voltage of the pixels to be input to the display panel from a first voltage value to a preset voltage value when the timing reaches a preset time point, and to control the power management chip to restore the power supply voltage of the pixels to be input to the display panel from the preset voltage value to the first voltage value after the vertical blanking period ends.

[0012] In the above-mentioned display device, the timing controller is also used to receive a variable refresh rate video source; and the display panel is used to display a first picture with a first refresh rate and a second picture with a second refresh rate according to the variable refresh rate video source; wherein, when the first refresh rate is greater than the second refresh rate, the number of preset time points during the vertical blanking period of the first picture is less than the number of preset time points during the vertical blanking period of the second picture; when the first refresh rate is less than the second refresh rate, the number of preset time points during the vertical blanking period of the first picture is greater than the number of preset time points during the vertical blanking period of the second picture.

[0013] In the above-mentioned display device, in the first picture, the preset voltage value is a second voltage value, and in the second picture, the preset voltage value is a third voltage value, and the second voltage value and the third voltage value are both greater than the first voltage value; when the first refresh rate is greater than the second refresh rate, the third voltage value is greater than the second voltage value; when the first refresh rate is less than the second refresh rate, the second voltage value is greater than the third voltage value.

[0014] In the above display device, the vertical blanking period includes a plurality of the preset time points, and the time interval between two adjacent preset time points is in the range of 1 millisecond to 3 milliseconds.

[0015] In the above display device, the vertical blanking period includes 1 to 6 preset time points.

[0016] In the display device and the driving method thereof provided in the embodiments of the present application, in a variable refresh rate scenario, by timing at the beginning of the vertical blanking period and increasing the power supply voltage from the first voltage value to the preset voltage value at a preset time point, the display brightness attenuation caused by the leakage current of the LTPS thin film transistor can be effectively compensated. By restoring the power supply voltage to the first voltage value after the vertical blanking period ends, the display of the next frame can be not affected, thereby ensuring the brightness uniformity of the display screen. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the brightness change of a traditional display panel at a refresh rate of 60 Hz.

[0018] Figure 2 Schematic diagram of the brightness change of a traditional display panel when the refresh rate is switched between 60 Hz and 120 Hz.

[0019] Figure 3 is a schematic diagram of a display device provided in an embodiment of the present application.

[0020] Figure 4 A schematic diagram of the time relationship between different frames of a display device and a driving method thereof provided in an embodiment of the present application at different refresh rates.

[0021] Figure 5 A schematic diagram of a voltage modification process of a display device and a driving method thereof provided in an embodiment of the present application.

[0022] Figure 6 A schematic diagram of the brightness compensation effect of the display device and the driving method thereof provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] The specific implementation methods of the present application are described in detail below with reference to the accompanying drawings.

[0024] The terms "first", "second" and similar words do not indicate any order, quantity or importance, but are only used to distinguish different technical features. The term "plurality" and similar words mean two or more, unless otherwise clearly defined.

[0025] The embodiments of the present application may be combined with each other.

[0026] The display device provided in the embodiments of the present application may be, for example, an OLED display device, a Mini-LED display device, or a Micro-LED display device. The embodiments of the present application are described using an OLED display device as an example.

[0027] like Figure 3As shown, an embodiment of the present application provides a display device, which includes a display panel, a timing controller, a source driving circuit (not shown in the figure) and a power management chip (the power management chip can be integrated with the timing controller into the same chip). The display panel is an organic light emitting diode display panel.

[0028] The display panel includes a display area and a non-display area. The display area is provided with m×n pixels arranged in an array, where m and n are integers greater than 1. The non-display area is located around the display area and is used to arrange a drive circuit and various signal lines. The display panel also includes a plurality of scan lines, a plurality of data lines and a gate drive circuit. The plurality of scan lines extend along a first direction and are arranged along a second direction, and the plurality of data lines extend along a second direction and are arranged along the first direction, and the first direction is perpendicular to the second direction. The gate drive circuit is provided in the non-display area and is electrically connected to the plurality of scan lines. The source drive circuit is electrically connected to the plurality of data lines through a flexible circuit board. The timing controller is electrically connected to the gate drive circuit and the source drive circuit, respectively.

[0029] The display panel includes an organic light emitting diode array substrate and an encapsulation layer. The organic light emitting diode array substrate includes a base substrate, a buffer layer arranged on the base substrate, an active layer arranged on the buffer layer, a gate insulating layer arranged on the active layer, a first metal layer arranged on the gate insulating layer, an interlayer insulating layer arranged on the first metal layer, a second metal layer arranged on the interlayer insulating layer, a planarization layer arranged on the second metal layer, a first electrode layer arranged on the planarization layer, a pixel defining layer arranged on the first electrode layer, an organic light emitting layer arranged in an opening area defined by the pixel defining layer, and a second electrode layer arranged on the organic light emitting layer. The first metal layer includes a scan line, a gate electrode, etc. The second metal layer includes a data line, a source electrode, a drain electrode, etc. The encapsulation layer is sealed and connected to the organic light emitting diode array substrate to prevent moisture and oxygen from invading the organic light emitting layer.

[0030] Each pixel includes a pixel driving circuit and an organic light emitting diode (light emitting device). The pixel driving circuit includes at least two thin film transistors and a storage capacitor. One of the thin film transistors is used as a switching transistor, and its gate is electrically connected to the corresponding scan line, and its source is electrically connected to the corresponding data line; the other thin film transistor is used as a driving transistor, and its gate is electrically connected to the drain of the switching transistor, the source is electrically connected to the first power supply voltage line, and the drain is electrically connected to the anode of the organic light emitting diode. One end of the storage capacitor is electrically connected to the gate of the driving transistor, and the other end is electrically connected to the source or drain of the driving transistor. The cathode of the organic light emitting diode is electrically connected to the second power supply voltage line.

[0031] The gate drive circuit includes n-stage cascaded gate drive subcircuits, and each stage of the gate drive subcircuit is electrically connected to a scan line. Under the control of the timing controller, the gate drive subcircuit outputs scan signals in sequence to scan each row of pixels in the display area line by line. Under the control of the timing controller, the source drive circuit generates and outputs data signals according to the image data. The timing controller is used to receive and process externally input image data and timing signals, generate control signals, and transmit image data to the source drive circuit. The power management chip is used to provide operating voltages for various parts of the display device, including providing a second power supply voltage for the cathode of the organic light emitting diode, providing a first power supply voltage for the first power supply voltage line, and providing a gate drive voltage for the gate drive circuit.

[0032] The timing controller is electrically connected to the display panel, the power management chip is electrically connected to the display panel and the timing controller, and the timing controller is connected to the power management chip via a communication interface, which includes an I2C interface, a GPIO interface or a programmable potentiometer.

[0033] The timing controller is used to receive a variable refresh rate video source VS.

[0034] The display panel is used to display a first picture with a first refresh rate and a second picture with a second refresh rate according to a variable refresh rate video source VS. Each frame displayed by the display panel includes a display period and a vertical blanking period. During the display period, the display data of the current frame is written into the pixel. After the display data is written into the pixel, due to the leakage current characteristics of the low-temperature polysilicon thin-film transistor of the pixel, the display brightness of the pixel will continue to decrease over time. Experimental tests have shown that at a refresh rate of 60 Hz, the display brightness of the pixels of the display panel shows a continuous attenuation trend; when the display panel switches between the two refresh rates of 60 Hz and 120 Hz, due to the different time lengths of the frames corresponding to 60 Hz and 120 Hz, the average brightness of the display panel at the two refresh rates is different, and the lower the refresh rate, the lower the average brightness.

[0035] The timing controller is used to start timing from the beginning of the vertical blanking period of a frame of an image displayed by the display panel of the display device, and is used to send a control signal CS to the power management chip of the display device when the timing reaches a preset time point, so as to control the power management chip to increase the power supply voltage VDD of the pixels to be input to the display panel from a first voltage value to a preset voltage value, and is used to send a control signal CS to the power management chip of the display device after the vertical blanking period ends, so as to control the power management chip to restore the power supply voltage VDD of the pixels to be input to the display panel from the preset voltage value to the first voltage value.

[0036] like Figure 4As shown, taking a display panel with 4K resolution and a variable refresh rate of 48 Hz to 144 Hz as an example: the number of pixel rows in the vertical effective display area is 2160 rows, and the number of pixel rows in the vertical blanking area is 62 rows. When the first start signal STV1 appears, the display data of the first frame begins to be written into the pixels of the display panel, and the display period of the first frame begins. The vertical blanking period of the first frame begins about 7 milliseconds after the display data is written. The time when the second start signal STV2 appears is the start time of the display period of the second frame. When the refresh rate of the second frame is 144 Hz, the second start signal STV2 appears earlier. At this time, the vertical blanking period of the first frame is the shortest, about 0.2 milliseconds; when the refresh rate of the second frame is 48 Hz, the second start signal STV2 appears later. At this time, the vertical blanking period of the first frame is the longest, about 13.7 milliseconds.

[0037] When the first refresh rate is greater than the second refresh rate, the number of preset time points during the vertical blanking period of the first picture is less than the number of preset time points during the vertical blanking period of the second picture.

[0038] When the first refresh rate is lower than the second refresh rate, the number of preset time points in the vertical blanking period of the first picture is greater than the number of preset time points in the vertical blanking period of the second picture.

[0039] In the first frame, the preset voltage value is a second voltage value, and in the second frame, the preset voltage value is a third voltage value. Both the second voltage value and the third voltage value are greater than the first voltage value.

[0040] When the first refresh rate is greater than the second refresh rate, the third voltage value is greater than the second voltage value.

[0041] When the first refresh rate is lower than the second refresh rate, the second voltage value is higher than the third voltage value.

[0042] The vertical blanking period includes a plurality of preset time points, and the time interval between two adjacent preset time points is in the range of 1 millisecond to 3 milliseconds.

[0043] like Figure 3 As shown, the timing controller includes a variable refresh rate optical compensation module, which times the current frame and controls the power management chip to adjust the power supply voltage through the communication interface at these preset time points.

[0044] like Figure 5 As shown, when the communication interface is an I2C interface, the time for I2C to configure the register is less than 1 millisecond, and the response time and voltage rise time (from 2 volts to 7.5 volts) of the power management chip are less than 1 millisecond. Based on this, the time interval between two adjacent preset time points can be set to 2 milliseconds.

[0045] The vertical blanking period includes 1 to 6 preset time points. Specifically, when the refresh rate of a frame is 144 Hz, the vertical blanking period includes 1 preset time point. When the refresh rate of a frame is 48 Hz, the vertical blanking period includes 6 preset time points.

[0046] An embodiment of the present application further provides a method for driving a display device, the method comprising:

[0047] The timing controller receives a variable refresh rate video source VS.

[0048] The display panel displays a first picture with a first refresh rate and a second picture with a second refresh rate according to the variable refresh rate video source VS.

[0049] Each frame of an image (including a first frame and a second frame) displayed by the display panel includes a display period and a vertical blanking period.

[0050] During the display period, the display data of the current frame is written into the pixel. After the display data is written into the pixel, the display brightness of the pixel will continue to decrease over time due to the leakage current characteristics of the low-temperature polysilicon thin-film transistor of the pixel. Experimental tests have shown that at a refresh rate of 60 Hz, the display brightness of the pixels of the display panel shows a continuous attenuation trend; when the display panel switches between the two refresh rates of 60 Hz and 120 Hz, the time length of the frame corresponding to 60 Hz is different from the time length of the frame corresponding to 120 Hz, resulting in a difference in the average brightness of the display panel at the two refresh rates, and the lower the refresh rate, the lower the average brightness.

[0051] In order to compensate for this brightness attenuation, the driving method further includes:

[0052] The timing starts from the beginning of the vertical blanking period of a frame displayed by the display panel.

[0053] When the timing reaches a preset time point, the timing controller sends a control signal CS to the power management chip of the display device through the communication interface to control the power management chip to increase the power supply voltage VDD of the pixel to be input to the display panel from the first voltage value to the preset voltage value. The communication interface can be, for example, an I2C interface, a GPIO interface, or a programmable potentiometer.

[0054] After the vertical blanking period ends, the timing controller sends a control signal CS to the power management chip of the display device through the communication interface to control the power management chip to restore the power voltage VDD to be input to the pixels of the display panel from the preset voltage value to the first voltage value.

[0055] like Figure 4As shown, taking a display panel with 4K resolution and a variable refresh rate of 48 Hz to 144 Hz as an example: the number of pixel rows in the vertical effective display area is 2160 rows, and the number of pixel rows in the vertical blanking area is 62 rows. When the first start signal STV1 appears, the display data of the first frame begins to be written into the pixels of the display panel, and the display period of the first frame begins. The vertical blanking period of the first frame begins about 7 milliseconds after the display data is written. The time when the second start signal STV2 appears is the start time of the display period of the second frame. When the refresh rate of the second frame is 144 Hz, the second start signal STV2 appears earlier. At this time, the vertical blanking period of the first frame is the shortest, about 0.2 milliseconds; when the refresh rate of the second frame is 48 Hz, the second start signal STV2 appears later. At this time, the vertical blanking period of the first frame is the longest, about 13.7 milliseconds.

[0056] In the first picture, the preset voltage value is the second voltage value, and in the second picture, the preset voltage value is the third voltage value, and both the second voltage value and the third voltage value are greater than the first voltage value. When the first refresh rate is greater than the second refresh rate, the third voltage value is greater than the second voltage value; when the first refresh rate is less than the second refresh rate, the second voltage value is greater than the third voltage value. In this way, corresponding compensation can be made for the degree of brightness attenuation under different refresh rates.

[0057] When the first refresh rate is greater than the second refresh rate, the number of preset time points during the vertical blanking period of the first picture is less than the number of preset time points during the vertical blanking period of the second picture; when the first refresh rate is less than the second refresh rate, the number of preset time points during the vertical blanking period of the first picture is greater than the number of preset time points during the vertical blanking period of the second picture.

[0058] The variable refresh rate optical compensation module in the timing controller times the current frame and controls the power management chip to adjust the power supply voltage through the communication interface at these preset time points. Figure 5 As shown, the communication interface can be an I2C interface, the time for configuring the I2C register is less than 1 millisecond, and the response time and voltage rise time (from 2 volts to 7.5 volts) of the power management chip are less than 1 millisecond.

[0059] The vertical blanking period includes a plurality of preset time points, and the time interval between two adjacent preset time points is in the range of 1 millisecond to 3 milliseconds. For example, the time interval between two adjacent preset time points is 2 milliseconds.

[0060] The vertical blanking period includes 1 to 6 preset time points. Specifically, when the refresh rate of a frame is 144 Hz, the vertical blanking period includes 1 preset time point. When the refresh rate of a frame is 48 Hz, the vertical blanking period includes 6 preset time points.

[0061] like Figure 6 As shown, the brightness of the picture displayed by the display device after compensation by the technical solution provided by the present application is shown as curve A1, while the brightness of the picture displayed by the display device without compensation by the technical solution provided by the present application is shown as curve A2. From the comparison between curve A1 and curve A2, it can be seen that the technical solution provided by the present application overcomes the problem that the brightness of the display panel in the traditional technical solution continues to decrease over time after the display data is written, that is, the technical solution provided by the present application can compensate for the brightness attenuation caused by the leakage current of the low-temperature polysilicon thin-film transistor at different refresh rates, and improve the brightness uniformity of the display picture. The technical solution provided by the present application will not cause picture delay and picture tearing, does not need to improve the specifications of the driver integrated circuit, and does not need to change the design of the display panel, and is suitable for most pixel circuits.

[0062] In actual application scenarios, under high temperature conditions, the leakage current of LTPS TFT will further increase, resulting in more serious brightness attenuation.

[0063] In view of the above technical problems, a first temperature sensor, a second temperature sensor, a third temperature sensor and a fourth temperature sensor are respectively arranged in the upper left corner, the upper right corner, the lower left corner and the lower right corner of the display panel. Each temperature sensor includes a temperature sensitive element and a signal conversion circuit. The temperature sensitive element is used to convert the detected temperature into a resistance value, and the signal conversion circuit is used to convert the resistance value into a digital temperature signal. The four temperature sensors are electrically connected to the timing controller through independent conductive wires, and each conductive wire adopts a double-layer wiring structure. The upper conductive wire is used to transmit the temperature signal, and the lower conductive wire is used to transmit the ground signal.

[0064] The timing controller includes a temperature data acquisition unit, a temperature data processing unit and a voltage compensation calculation unit. The temperature data acquisition unit includes four signal receiving subunits and a data buffer subunit. The four signal receiving subunits correspond to four temperature sensors one by one, and are used to receive and analyze the digital temperature signals sent by the temperature sensors. The data buffer subunit is used to temporarily store the temperature values ​​obtained by the analysis. The temperature data processing unit includes a data screening subunit and a weighted calculation subunit. The data screening subunit judges the validity of the cached temperature values ​​and eliminates abnormal temperature values. The weighted calculation subunit assigns different weight coefficients according to the positions of the four temperature sensors, performs weighted averaging on the screened temperature values, and obtains the current temperature value of the display panel. Specifically, the weight coefficient of the temperature sensor located near the center area of ​​the display panel is larger, and the weight coefficient of the temperature sensor located at the edge area of ​​the display panel is smaller.

[0065] The voltage compensation calculation unit includes a temperature interval judgment subunit, a lookup table storage subunit and a voltage adjustment subunit. The temperature interval judgment subunit divides the temperature range of 0°C to 70°C into 7 temperature intervals. The lookup table storage subunit stores a temperature-voltage compensation correspondence table, which records the adjustment coefficients of the preset voltage values ​​corresponding to the 7 temperature intervals. Specifically, when the temperature is in the range of 0°C to 15°C, the adjustment coefficient is 0.6, and the preset voltage value is reduced by 40%; when the temperature is in the range of 15°C to 25°C, the adjustment coefficient is 0.8, and the preset voltage value is reduced by 20%; when the temperature is in the range of 25°C to 35°C, the adjustment coefficient is 1.0, and the preset voltage value remains unchanged; when the temperature is in the range of 35°C to 45°C, the adjustment coefficient is 1.2, and the preset voltage value is increased by 20%; when the temperature is in the range of 45°C to 55°C, the adjustment coefficient is 1.4, and the preset voltage value is increased by 40%; when the temperature is in the range of 55°C to 65°C, the adjustment coefficient is 1.6, and the preset voltage value is increased by 60%; when the temperature is in the range of 65°C to 70°C, the adjustment coefficient is 1.8, and the preset voltage value is increased by 80%. The voltage adjustment subunit multiplies the adjustment coefficient determined by the temperature interval judgment subunit with the original preset voltage value to obtain a new preset voltage value.

[0066] The timing controller also includes a temperature threshold storage unit and an alarm control unit. The temperature threshold storage unit stores an upper temperature threshold and a lower temperature threshold. When the alarm control unit detects that the current temperature value of the display panel exceeds the threshold range, it sends an over-temperature warning signal to the system through the main controller. The timing controller sends the new preset voltage value to the power management chip through the SPI communication interface. The power management chip includes a voltage conversion circuit and an output control circuit. The voltage conversion circuit generates a corresponding output voltage according to the received new preset voltage value. The output control circuit applies the output voltage to the pixel circuit of the display panel to achieve temperature-based voltage compensation.

[0067] In actual application scenarios, under different grayscale voltages, the degree of brightness attenuation caused by leakage current is different.

[0068] In view of the above technical problems, the timing controller includes a grayscale statistics unit, a lookup table storage unit and a voltage selection unit. The grayscale statistics unit includes a data receiving subunit, a counting subunit and an interval judgment subunit. The data receiving subunit receives the RGB display data of the current frame through the display interface and converts the RGB display data into corresponding grayscale values. The counting subunit accumulates and counts the number of occurrences of each grayscale value to obtain a grayscale distribution histogram. The interval judgment subunit determines the interval where the grayscale value corresponding to the peak value in the grayscale distribution histogram is located as the main grayscale interval.

[0069] The lookup table storage unit includes a storage control subunit and a plurality of lookup table subunits. The storage control subunit is used to store and call the data in the lookup table subunit. Each lookup table subunit corresponds to a specific refresh rate and is used to store the preset voltage values ​​corresponding to different grayscale intervals under the refresh rate. Specifically, five lookup table subunits are provided in the lookup table storage unit, corresponding to five refresh rates of 48 Hz, 60 Hz, 90 Hz, 120 Hz and 144 Hz, respectively. Each lookup table subunit adopts a two-dimensional array structure, and divides the grayscale value range of 0 to 255 into 8 grayscale intervals, and each grayscale interval corresponds to a preset voltage value.

[0070] In the lookup table corresponding to the 48 Hz refresh rate, the grayscale range of 0 to 31 corresponds to the first preset voltage value of 7.2 volts, the grayscale range of 32 to 63 corresponds to the second preset voltage value of 7.0 volts, the grayscale range of 64 to 95 corresponds to the third preset voltage value of 6.8 volts, the grayscale range of 96 to 127 corresponds to the fourth preset voltage value of 6.6 volts, the grayscale range of 128 to 159 corresponds to the fifth preset voltage value of 6.4 volts, the grayscale range of 160 to 191 corresponds to the sixth preset voltage value of 6.2 volts, the grayscale range of 192 to 223 corresponds to the seventh preset voltage value of 6.0 volts, and the grayscale range of 224 to 255 corresponds to the eighth preset voltage value of 5.8 volts.

[0071] In the lookup table corresponding to the 60 Hz refresh rate, the preset voltage value corresponding to each grayscale interval is 0.2 volts higher than that at the 48 Hz refresh rate. In the lookup table corresponding to the 90 Hz refresh rate, the preset voltage value corresponding to each grayscale interval is 0.2 volts higher than that at the 60 Hz refresh rate. In the lookup table corresponding to the 120 Hz refresh rate, the preset voltage value corresponding to each grayscale interval is 0.2 volts higher than that at the 90 Hz refresh rate. In the lookup table corresponding to the 144 Hz refresh rate, the preset voltage value corresponding to each grayscale interval is 0.2 volts higher than that at the 120 Hz refresh rate.

[0072] The voltage selection unit includes a refresh rate detection subunit, a lookup table selection subunit and a voltage output subunit. The refresh rate detection subunit determines the current refresh rate by monitoring the frequency of the frame synchronization signal. The lookup table selection subunit selects the corresponding lookup table subunit from the lookup table storage unit according to the current refresh rate. The voltage output subunit reads the corresponding preset voltage value from the selected lookup table subunit according to the main grayscale interval.

[0073] The voltage selection unit also includes a voltage smoothing subunit for smoothing the preset voltage value. When the difference between the preset voltage values ​​of two adjacent frames is greater than the preset threshold, the voltage smoothing subunit evenly distributes the change in the preset voltage value to multiple consecutive frames to avoid display abnormalities caused by voltage mutations. The voltage selection unit sends the processed preset voltage value to the power management chip through the SPI communication interface. The power management chip includes a voltage regulation circuit and an output buffer circuit. The voltage regulation circuit generates a corresponding output voltage based on the received preset voltage value, and the output buffer circuit outputs the output voltage to the power supply terminal of the pixel circuit of the display panel to achieve grayscale-based voltage compensation.

[0074] In actual application scenarios, when the refresh rate is switched quickly, the display panel may experience a sudden change in brightness.

[0075] In view of the above technical problems, the timing controller includes a refresh rate switching detection module and a voltage gradient control module, and the refresh rate switching detection module is electrically connected to the voltage gradient control module. The refresh rate switching detection module includes a frame synchronization signal detection unit and a refresh rate calculation unit, the frame synchronization signal detection unit receives the frame synchronization signal of the variable refresh rate video source VS, and the refresh rate calculation unit calculates the current refresh rate according to the time interval between two adjacent frame synchronization signals. When the refresh rate calculation unit detects that the refresh rate has changed, it sends a refresh rate switching signal to the voltage gradient control module. The voltage gradient control module includes a voltage gradient unit and a frame counting unit, and the voltage gradient unit pre-stores target preset voltage values ​​corresponding to different refresh rates. After receiving the refresh rate switching signal, the frame counting unit starts counting, and controls the voltage gradient unit to gradually adjust the preset voltage value from the current value to the target value within 8 consecutive frames. Specifically, the voltage gradient unit evenly distributes the difference between the current preset voltage value and the target preset voltage value to 8 frames, and adjusts the preset voltage value by 1 / 8 of the difference during the vertical blanking period of each frame. For example, when the refresh rate is switched from 60 Hz to 120 Hz, if the current preset voltage value is 7.5 volts and the target preset voltage value is 5.5 volts, the preset voltage value is reduced by 0.25 volts for each frame within 8 frames. The voltage gradient unit sends the preset voltage value corresponding to each frame to the power management chip through the communication interface, and the power management chip adjusts the power supply voltage VDD of the pixel to be input to the display panel according to the received preset voltage value.

[0076] In actual application scenarios, leakage current characteristics of different areas of a display panel may differ.

[0077] In view of the above technical problems, the display panel is equally divided into 4 areas in the horizontal direction and the vertical direction respectively, so that the display panel is divided into 16 compensation areas. The timing controller includes a parameter storage unit and a voltage distribution unit, and the compensation coefficient corresponding to each compensation area is stored in the parameter storage unit. The voltage distribution unit includes 16 independent voltage control channels, and each voltage control channel corresponds to a compensation area one by one. Each voltage control channel includes a voltage adjustment unit and a timing control unit, and the voltage adjustment unit is used to adjust the preset voltage value according to the compensation coefficient of the corresponding compensation area, and the timing control unit is used to control the working timing of the voltage adjustment unit. Specifically, the pixels of each compensation area of ​​the display panel are connected to the power management chip through an independent power line. At each preset time point during the vertical blanking period, the 16 voltage control channels work simultaneously, and the voltage adjustment unit of each voltage control channel multiplies the current preset voltage value with the compensation coefficient of the compensation area corresponding to the channel to obtain the actual preset voltage value of the compensation area. The voltage distribution unit sends the actual preset voltage values ​​of the 16 compensation areas to the power management chip through the communication interface, and the power management chip adjusts the power supply voltages of the pixels of the 16 compensation areas through 16 independent power lines. The compensation coefficient ranges from 0.8 to 1.2, and the specific value of the compensation coefficient can be determined by testing the actual brightness attenuation of each compensation area. For example, for a compensation area with a larger leakage current, the compensation coefficient can be set to 1.2, so that the area obtains a larger voltage compensation; for a compensation area with a smaller leakage current, the compensation coefficient can be set to 0.8, so that the area obtains a smaller voltage compensation.

[0078] In actual application scenarios, frequent voltage adjustments may increase the power consumption of the display device.

[0079] In view of the above technical problems, the timing controller includes a content analysis module and a power consumption optimization module. The content analysis module includes a frame comparison unit and a feature extraction unit. The frame comparison unit is used to compare the display data of two adjacent frames, and the feature extraction unit is used to extract the dynamic range characteristics of the current frame. The power consumption optimization module includes a scene judgment unit, a compensation strategy unit and a voltage control unit. The scene judgment unit divides the display scene into three categories according to the comparison result of the frame comparison unit: static scene, low dynamic scene and high dynamic scene. Among them, when the display data of 8 consecutive frames are exactly the same, it is determined to be a static scene; when the number of pixels that have changed in 8 consecutive frames is less than 20% of the total number of pixels, it is determined to be a low dynamic scene; the rest of the cases are determined to be high dynamic scenes. The compensation strategy unit determines the compensation strategy according to the scene type and dynamic range characteristics. Specifically, in a static scene, voltage compensation is performed every 8 frames, and the adjustment range of the preset voltage value is 50% of the original adjustment range; in a low dynamic scene, voltage compensation is performed every 4 frames, and the adjustment range of the preset voltage value is 75% of the original adjustment range; in a high dynamic scene, the original compensation frequency and adjustment range are maintained. The voltage control unit includes a voltage divider circuit and a switch circuit. The voltage divider circuit is used to generate preset voltage values ​​of different amplitudes, and the switch circuit is used to control the timing of voltage compensation. The voltage control unit sends the preset voltage value corresponding to the compensation strategy to the power management chip through the communication interface, and the power management chip adjusts the power supply voltage of the pixels of the display panel according to the received preset voltage value. Through this adaptive compensation mechanism based on display content, power consumption can be effectively reduced while ensuring the display effect.

[0080] In the display device and the driving method thereof provided in the embodiments of the present application, in a variable refresh rate scenario, by timing at the beginning of the vertical blanking period and increasing the power supply voltage from the first voltage value to the preset voltage value at a preset time point, the display brightness attenuation caused by the leakage current of the LTPS thin film transistor can be effectively compensated. By restoring the power supply voltage to the first voltage value after the vertical blanking period ends, the display of the next frame can be not affected, thereby ensuring the brightness uniformity of the display screen.

[0081] In addition, the display device and the driving method thereof provided by the embodiment of the present application also adapt to the brightness compensation requirements under different refresh rates by adjusting the number of preset time points. When the first refresh rate is greater than the second refresh rate, since the frame time corresponding to the second refresh rate is longer and the brightness attenuation is more obvious, more preset time points are set during the vertical blanking period of the second picture for compensation; conversely, when the first refresh rate is less than the second refresh rate, more preset time points are set during the vertical blanking period of the first picture. In this way, the brightness attenuation problem under different refresh rates can be solved in a targeted manner.

[0082] In addition, since the voltage compensation operation of the technical solution of the present application is performed during the vertical blanking period, it will not affect the picture display during the normal display period, and thus will not cause problems such as picture delay and picture tearing.

[0083] The embodiments of the present application are described in detail above, and the contents of this specification should not be construed as limiting the scope of protection of the present application.

Claims

1. A method for driving a display device, characterized in that: include: Timing starts from the beginning of the vertical blanking period of a frame displayed by the display panel of the display device; When the timing reaches a preset time point, controlling the power management chip of the display device to increase the power voltage of the pixels to be input to the display panel from the first voltage value to the preset voltage value; as well as After the vertical blanking period ends, the power management chip is controlled to restore the power voltage of the pixels to be input to the display panel from the preset voltage value to the first voltage value.

2. The driving method according to claim 1, characterized in that: Before timing starts from the beginning of a vertical blanking period of a frame displayed by the display panel of the display device, the driving method further includes: receiving a variable refresh rate video source; and Displaying a first picture with a first refresh rate and a second picture with a second refresh rate according to the variable refresh rate video source; Wherein, when the first refresh rate is greater than the second refresh rate, the number of the preset time points during the vertical blanking period of the first picture is less than the number of the preset time points during the vertical blanking period of the second picture; When the first refresh rate is lower than the second refresh rate, the number of the preset time points during the vertical blanking period of the first picture is greater than the number of the preset time points during the vertical blanking period of the second picture.

3. The driving method according to claim 2, characterized in that: In the first picture, the preset voltage value is a second voltage value, and in the second picture, the preset voltage value is a third voltage value, and both the second voltage value and the third voltage value are greater than the first voltage value; When the first refresh rate is greater than the second refresh rate, the third voltage value is greater than the second voltage value; When the first refresh rate is lower than the second refresh rate, the second voltage value is higher than the third voltage value.

4. The driving method according to claim 1, characterized in that: The vertical blanking period includes a plurality of the preset time points, and a time interval between two adjacent preset time points is in a range from 1 millisecond to 3 milliseconds.

5. The driving method according to claim 4, characterized in that: The vertical blanking period includes 1 to 6 preset time points.

6. A display device, characterized in that: include: Display panel; A timing controller, electrically connected to the display panel; as well as A power management chip, electrically connected to the display panel and the timing controller; Among them, the timing controller is used to count from the beginning of the vertical blanking period of a frame of image displayed by the display panel of the display device, and is used to control the power management chip of the display device to increase the power supply voltage of the pixels to be input to the display panel from a first voltage value to a preset voltage value when the timing reaches a preset time point, and is used to control the power management chip to restore the power supply voltage of the pixels to be input to the display panel from the preset voltage value to the first voltage value after the vertical blanking period ends.

7. The display device according to claim 6, characterized in that The timing controller is also used to receive a variable refresh rate video source; and The display panel is used to display a first picture with a first refresh rate and a second picture with a second refresh rate according to the variable refresh rate video source; Wherein, when the first refresh rate is greater than the second refresh rate, the number of the preset time points during the vertical blanking period of the first picture is less than the number of the preset time points during the vertical blanking period of the second picture; When the first refresh rate is lower than the second refresh rate, the number of the preset time points during the vertical blanking period of the first picture is greater than the number of the preset time points during the vertical blanking period of the second picture.

8. The display device according to claim 7, characterized in that: In the first picture, the preset voltage value is a second voltage value, and in the second picture, the preset voltage value is a third voltage value, and both the second voltage value and the third voltage value are greater than the first voltage value; When the first refresh rate is greater than the second refresh rate, the third voltage value is greater than the second voltage value; When the first refresh rate is lower than the second refresh rate, the second voltage value is higher than the third voltage value.

9. The display device according to claim 1, wherein: The vertical blanking period includes a plurality of the preset time points, and a time interval between two adjacent preset time points is in a range from 1 millisecond to 3 milliseconds.

10. The display device according to claim 9, characterized in that The vertical blanking period includes 1 to 6 preset time points.

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