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EP-4131238-B1 - PIXEL CIRCUIT AND DRIVING METHOD THEREFOR, AND DISPLAY APPARATUS AND DRIVING METHOD THEREFOR

EP4131238B1EP 4131238 B1EP4131238 B1EP 4131238B1EP-4131238-B1

Inventors

  • YU, Ziyang
  • WANG, Zhu
  • HU, SHENG
  • LIU, Tianliang
  • LIU, GUO

Dates

Publication Date
20260506
Application Date
20200331

Claims (7)

  1. A display device (1200) comprising: a plurality of pixel units (11) arranged in a matrix, wherein each pixel unit (11) comprises a light-emitting element (112, OLED) and a pixel driving circuit (111, 40, 50, 60) for driving the light-emitting element (112, OLED) to emit light, and the pixel driving circuit (111, 40, 50, 60) and the light-emitting element (112, OLED) are electrically connected to a first node (N1); a first compensation sub-circuit (12) electrically connected to each pixel driving circuit (111, 40, 50, 60) in each of the plurality of pixel units (11), wherein the first compensation sub-circuit (12) is configured to provide an initialization signal (Vref) to the pixel driving circuit (111, 40, 50, 60), and to obtain a voltage at the first node (N1) when the light-emitting element (112, OLED) emits light via the pixel driving circuit (111, 40, 50, 60), and to generate a compensation data signal (Da k ) based on the voltage at the first node (N1); and a second compensation sub-circuit (13) electrically connected to each pixel driving circuit (111, 40, 50, 60) in each of the plurality of pixel units (11) and configured to keep the voltage at the first node (N1) within a set operating voltage range of the light-emitting element (112), wherein the pixel driving circuit (111, 40, 50, 60) is further configured to initialize the first node (N1) based on the initialization signal (Vref), and to use the compensation data signal (Da k ) to drive the light-emitting element (112, OLED) to emit light, wherein the pixel driving circuit (111, 40, 50, 60) comprises: a driving sub-circuit (41) configured to generate a current for causing the light-emitting element (112, OLED) to emit light; a light emission control sub-circuit (42, 52) electrically connected to the light-emitting element (112, OLED) and the driving sub-circuit (41), and configured to receive a first control signal (CON1) and supply a current for causing the light-emitting element (112, OLED) to emit light to the light-emitting element (112, OLED) under the control of the first control signal (CON1); a driving control sub-circuit (43, 53) electrically connected to the driving sub-circuit (41), and configured to receive the compensation data signal (Da k ) and a second control signal (CON2), and to provide the compensation data signal (Da k ) to the driving sub-circuit (41) at a third node (N3) under the control of the second control signal (CON2); and a reset sub-circuit (44, 54) electrically connected to the driving sub-circuit (41) and the first compensation sub-circuit (12), and configured to receive a third control signal (CON3) and a fourth control signal (CON4), and to apply the initialization signal (Vref) provided by the first compensation sub-circuit (12) to the first node under the control of the third control signal (CON3) and the fourth control signal (CON4) or to output the voltage at the first node (N1) when the light-emitting element (112, OLED) emits light to the first compensation sub-circuit (12) under the control of the third control signal (CON3) and the fourth control signal (CON4), wherein the driving sub-circuit (41) comprises a driving transistor (DTFT), a fourth transistor (T4) and a storage capacitor (C1), wherein a gate of the driving transistor (DTFT) is electrically connected to a first end of the storage capacitor (C1), a drain of the driving transistor (DTFT) and the light emission control sub-circuit (42, 52) are electrically connected to a second node (N2), and a source of the driving transistor (DTFT) and the light emission control sub-circuit (42, 52) are electrically connected to the third node (N3); a gate of the fourth transistor (T4) is electrically connected to receive the second control signal (CON2), a first electrode of the fourth transistor (T4) is electrically connected to the first end of the storage capacitor (C1), and a second electrode of the fourth transistor (T4) is electrically connected to the second node (N2); a second end of the storage capacitor (C1) is electrically connected to the first node (N1), wherein the driving control sub-circuit (43, 53) comprises a seventh transistor (T7), a gate of the seventh transistor (T7) is electrically connected to receive the second control signal (CON2), a first electrode of the seventh transistor (T7) is electrically connected to receive the compensation data signal (Da k ), and a second electrode of the seventh transistor (T7) is electrically connected to the third node (N3); wherein the second compensation sub-circuit (13) comprises a plurality of compensation capacitors (C2) which correspond to respective pixel driving circuits (111, 40, 50, 60), and a first end of each of the compensation capacitors (C2) is electrically connected to the first node (N1), and the second end of each of the compensation capacitors (C2) is electrically connected to the gate of the seventh transistor (T7), and wherein the reset sub-circuit (44, 54) comprises an eighth transistor (T8) and a ninth transistor (T9), a gate of the eighth transistor (T8) is electrically connected to receive the third control signal (CON3), a first electrode of the eighth transistor (T8) is electrically connected to the first node (N1), and a second electrode of the eighth transistor (T8) is electrically connected to the first compensation sub-circuit (12); a gate of the ninth transistor (T9) is electrically connected to receive the fourth control signal (CON4), a first electrode of the ninth transistor (T9) is electrically connected to receive a first voltage signal (ELVDD), and a second electrode of the ninth transistor (T9) is electrically connected to the first end of the storage capacitor (C1).
  2. The display device (1200) according to claim 1, wherein the first compensation sub-circuit (20) comprises: a switching sub-circuit (21) configured to receive a first switching signal (SW1) and a second switching signal (SW2), and to output the initialization signal (Vref) at an output terminal of the switching sub-circuit (21) under the control of the first switching signal (SW1) and keep the output terminal in a floating state under the control of the second switching signal (SW2); a sampling sub-circuit (22) configured to obtain the voltage at the first node (N1) while the output terminal is kept in the floating state; and a data compensation sub-circuit (23) configured to generate the compensation data signal (Da k ) based on a preset compensation model and the voltage at the first node (N1).
  3. The display device (1200) according to claim 2, wherein the switching sub-circuit (21) comprises a first transistor (T1), a second transistor (T2), and a third transistor (T3), wherein a gate of the first transistor (T1) is electrically connected to receive the first switching signal (SW1), a first electrode of the first transistor (T1) is electrically connected to receive the initialization signal (Vref), and a second electrode of the first transistor (T1) is electrically connected to a second electrode of the second transistor (T2) and serve as the output terminal; a gate of the second transistor (T2) is electrically connected to receive the second switching signal (SW2), and a first electrode of the second transistor (T2) is electrically connected to a first electrode of the third transistor (T3); a gate of the third transistor (T3) is electrically connected to receive a sampling control signal (SW3), and a second electrode of the third transistor (T3) is electrically connected to the sampling sub-circuit (22).
  4. The display device (1200) according to any one of claims 2 to 3, wherein the light emission control sub-circuit (42, 52) comprises a fifth transistor (T5) and a sixth transistor (T6), wherein a gate of the fifth transistor (T5) is electrically connected to receive the first control signal (CON1), a first electrode of the fifth transistor (T5) is electrically connected to receive the first voltage signal (ELVDD), and a second electrode of the fifth transistor (T5) is electrically connected to the second node (N2); a gate of the sixth transistor (T6) is electrically connected to receive the first control signal (CON1), a first electrode of the sixth transistor (T6) is electrically connected to the third node (N3), and a second electrode of the sixth transistor (T6) is electrically connected to the first node (N1).
  5. A method suitable for driving the display device (1200) according to claims 1 to 4, comprising: compensating (S710) a threshold voltage of the pixel driving circuit (111, 40, 50, 60), so as to eliminate influence of the threshold voltage on a current flowing through the light-emitting element (112, OLED); generating (S720) the compensation data signal (Da k ) by using the first compensation sub-circuit (12); and driving (S730) the light-emitting element (112, OLED) in each pixel unit (11) to emit light based on the compensation data signal (Da k ).
  6. The method (700) according to claim 5, wherein the compensation data signal (Da k ) is generated based on light-emitting brightness of a selected light-emitting element before driving the light-emitting element (112, OLED) in each pixel unit (11) to emit light; or wherein, in a process of driving the light-emitting element (112, OLED) in each pixel unit (11) to emit light, the compensation data signal (Da k ) is generated based on light-emitting brightness of a light-emitting element in each of selected pixel units or based on the light-emitting brightness of the light-emitting element in each pixel unit, wherein generating the compensation data signal (Da k ) by using the first compensation sub-circuit (12) comprises: in a first sampling period, providing a first switching signal (SW1) having a second level, a sampling control signal (SW3) having a second level, a second switching signal (SW2) having a first level, so that the output terminal of the switching sub-circuit (21) is kept in a floating state, providing a third control signal (CON3) having a first level, so that the eighth transistor (T8) is turned on, so as to obtain the voltage at the first node (N1) at the output terminal; and in a second sampling period, providing the sampling control signal (SW3) having a first level, wherein the sampling sub-circuit (22) is connected to the output terminal to sample the voltage at the first node (N1), the data compensation sub-circuit (23) is configured to compare the collected voltage at the first node (N1) with an expected voltage of the light-emitting element (112, OLED) under a brightness, and a compensation signal is obtained according to a compensation model in the data compensation sub-circuit (23), and the compensation signal is fed back to a data signal through gamma voltage, so as to generate a compensation data signal (Da k ).
  7. The method (700) according to any one of claims 5 to 6, wherein driving the light-emitting element (112, OLED) in each pixel unit (11) to emit light based on the compensation data signal (Da k ) comprises: in a first driving period, providing the first switching signal (SW1) having a first level, the second switching signal (SW2) having a second level, so that the output terminal of the switching sub-circuit (21) outputs an initialization voltage, providing the third control signal (CON3) having a first level, so that the eighth transistor (T8) is turned on, so as to initialize the voltage at the first node (N1) to the initialization voltage, providing the fourth control signal (CON4) having a first level, so that the ninth transistor (T9) is turned on, and the first end of the storage capacitor (C1) and the gate of the driving transistor (DTFT) are initialized to a first voltage; in a second driving period, providing the second control signal (CON2) having a first level, so that the fourth transistor (T4) and the seventh transistor (T7) are turned on, and the drain and the gate of the driving transistor (DTFT) are electrically connected, charges at the first end of the storage capacitor (C1) flow to a data signal line through the fourth transistor (T4), the driving transistor (DTFT) and the seventh transistor (T7), wherein the third control signal (CON3) is maintained at a high level, so that the third transistor (T3) is maintained to be turned on, and an anode of the light-emitting element (112, OLED) is maintained at the initialization voltage; and in a third driving period, providing the second control signal (CON2), the third control signal (CON3), and the fourth control signal (CON4) which all have a second level, so that the fourth transistor (T4), the seventh transistor (T7), the eighth transistor (T8) and the ninth transistor (T9) are turned off, providing the first control signal (CON1) having a first level, so that the fifth transistor (T5) and the sixth transistor (T6) are turned on, and the current flows through the light-emitting element (112, OLED) so that the light-emitting element (112, OLED) emits light.

Description

TECHNICAL FIELD Embodiments of the present disclosure relate to the field of display technology, in particular to a pixel circuit and a driving method thereof, a display device and a driving method thereof. BACKGROUND Semiconductor devices, such as organic light-emitting diodes (OLEDs), use a current driving mode for light-emitting display, thus current stability requirements for driving TFTs (DTFTs) and OLED devices are very high. Meanwhile, OLED devices may deteriorate due to device aging after long-term use, resulting in image quality degradation problems such as afterimages during display. EP 3159883 A1 discloses a display device including a display panel and a scan driver. The display panel displays an image. The scan driver includes a scan signal generation circuit disposed on one side of the display panel, and an emission signal generation circuit disposed on the other side of the display panel. The emission signal generation circuit outputs an emission signal having at least two Logic High sections in response to an external clock signal and first and second scan signals output from the scan signal generation circuit. CN 110189701 A discloses a pixel driving circuit, a driving method of the pixel driving circuit, a display panel and a display device. The pixel driving circuit comprises a drive circuit, an energy storage circuit; a data and sensing line; a first initialization circuit; a second initialization circuit and a data writing circuit, wherein in the display mode, the data and sensing line writes data voltage into the control end of the driving circuit through the data write-in circuit; in the sensing mode, the data and sensing line receives the sensing data output by the driving circuit through the second initialization circuit to obtain external compensation value of the drive circuit. CN 106205486 A discloses that an organic light emitting display comprises a display panel having a plurality of pixels, a gate drive circuit that drives scan lines and emission lines on the display panel, and a data drive circuit that drives data lines on the display panel. Each of the pixels is arranged in an nth row. A single frame for the organic light emitting display comprises an initial period in which the gate voltage of a driving transistor is initialized, a sampling period for compensating the threshold voltage of the driving transistor, and a light emission period in which an organic light emitting diode emits light. A value corresponding to an image signal to be displayed by the organic light emitting diode is applied to a data line during the sampling period, and an initial voltage is applied to one electrode of a capacitor during the initial period. WO 2017/173767 A1 discloses a pixel driving circuit configured to operate in a display cycle including sequentially an initialization period, a compensation period, and a light-emitting period, the pixel driving circuit including a driving transistor having a gate, a source, and a drain; a first storage capacitor having a first terminal connected to the gate of the driving transistor and a second terminal connected to a first power signal input port; an emission control sub-circuit disposed between the source of the driving transistor and the first power signal input port; a data write-in sub-circuit disposed between a data input port and the drain of the driving transistor which is also connected to the emission control sub-circuit; a compensation sub-circuit disposed between the source of the driving transistor and the first terminal of the first storage capacitor; and a light emitting device having a first terminal connected to the emission control sub-circuit and a second terminal connected to a second power signal input port; the data write-in sub-circuit is configured to control a data voltage signal to be passed into the drain of the driving transistor during the compensation period; the compensation sub-circuit is configured to control a connection between the source and the gate of the driving transistor during the compensation period to set the driving transistor to a conduction state for inducing a source-to-drain current until a gate voltage of the driving transistor reaches a value substantially equal to the data voltage signal plus a threshold voltage of the driving transistor. US 2016/189614 A1 discloses that an organic light-emitting diode display panel and an OLED display device have a sensing driving stabilizer that can increase accuracy in sensing and compensation by providing potential stability to a reference voltage line acting as a sensing line during the sensing driving. SUMMARY The invention is set out by the appended set of claims. Embodiments of the present disclosure provide a pixel circuit and a driving method thereof, as well as a display device and a driving method thereof. We also disclose a pixel circuit comprising: a plurality of pixel units arranged in a matrix, wherein each pixel unit comprises a light-emitting ele