OLED PIXEL CIRCUIT AND METHOD FOR DRIVING THE SAME, DISPLAY APPARATUS

• US 20190164500A1
• Filed: 09/21/2018
• Published: 05/30/2019
• Est. Priority Date: 11/29/2017
• Status: Active Grant

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: BOE Technology Group Co., Ltd.
• Inventors: SHI, Ling
• Granted Patent: US 10,726,790 B2
• Time in Patent Office: Days
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/043 Compensation electrodes or other additional electrodes in matrix displays related to distortions or compensation signals, e.g. for modifying TFT threshold voltage in column driver
• CPC Class Codes: G09G 2300/0439 Pixel structures
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays

Abstract

An OLED pixel circuit includes an initialization and compensation sub-circuit configured to initialize a driving sub-circuit and compensate a threshold voltage of the driving sub-circuit; a data writing sub-circuit configured to input a signal of a second signal end to the driving sub-circuit; a light-emitting control sub-circuit configured to input a signal of the first voltage end to the driving sub-circuit, and input a driving signal output by the driving sub-circuit to a light emitting sub-circuit; the driving sub-circuit configured to output the driving signal; and the light emitting sub-circuit configured to emit light.

Claims

1. An OLED pixel circuit, comprising:

an initialization and compensation sub-circuit, connected to a driving sub-circuit, a first signal end and an initial voltage end, and configured to initialize the driving sub-circuit and compensate a threshold voltage of the driving sub-circuit according to a signal input by the initial voltage end under control of a signal from the first signal end;

a data writing sub-circuit, connected to the driving sub-circuit, the first signal end and a second signal end, and configured to input a signal of the second signal end to the driving sub-circuit under control of a signal from the first signal end;

a light-emitting control sub-circuit, connected to the driving sub-circuit, a light emitting sub-circuit, an enable signal end and a first voltage end; and

configured to input a signal of the first voltage end to the driving sub-circuit, and to input a driving signal output by the driving sub-circuit to the light emitting sub-circuit under control of a signal from the enable signal end;

the driving sub-circuit, further connected to a third signal end, and configured to output the driving signal under control of a signal from the third signal end and in a case of the signal of the first voltage end being input to the driving sub-circuit; and

the light emitting sub-circuit, further connected to a second voltage end, and configured to emit light under a driving of the second voltage end and the driving signal output by the light-emitting control sub-circuit.

2. The OLED pixel circuit according to claim 1, wherein, the enable signal end and the third signal end are connected with a same signal input end.

3. The OLED pixel circuit according to claim 1, wherein, the initialization and compensation sub-circuit is further connected to the light emitting sub-circuit, and is configured to initialize the light emitting sub-circuit according to a signal input by the initial voltage end under control of a signal from the first signal end.

4. The OLED pixel circuit according to claim 1, wherein, the driving sub-circuit comprises a first transistor, a driving transistor and a reservoir capacitor, wherein

a first end of the reservoir capacitor is connected to the data writing sub-circuit, and a second end of the reservoir capacitor is connected to a first electrode of the driving transistor;

a gate electrode of the first transistor is connected to the third signal end, a first electrode of the first transistor is connected to the first end of the reservoir capacitor, and a second electrode of the first transistor is connected to a gate electrode of the driving transistor; and

the gate electrode of the driving transistor is further connected to the initialization and compensation sub-circuit, the first electrode of the driving transistor is further connected to the light-emitting control sub-circuit, and a second electrode of the driving transistor is connected to the initialization and compensation sub-circuit and the light-emitting control sub-circuit.

5. The OLED pixel circuit according to claim 1, wherein, the initialization and compensation sub-circuit comprises a second transistor and a third transistor, wherein

a gate electrode of the second transistor is connected to the first signal end, a first electrode of the second transistor is connected to the initial voltage end, and a second electrode of the second transistor is connected to the driving sub-circuit;

and

a gate electrode of the third transistor is connected to the first signal end, a first electrode of the third transistor is connected to the first electrode of the second transistor, and a second electrode of the third transistor is connected to the driving sub-circuit.

6. The OLED pixel circuit according to claim 5, wherein, the initialization and compensation sub-circuit further comprises a fourth transistor, wherein

a gate electrode of the fourth transistor is connected to the first signal end, a first electrode of the fourth transistor is connected to the initial voltage end, and a second electrode of the fourth transistor is connected to the light emitting sub-circuit.

7. The OLED pixel circuit according to claim 1, wherein, the data writing sub-circuit comprises a fifth transistor, wherein

a gate electrode of the fifth transistor is connected to the first signal end, a first electrode of the fifth transistor is connected to the second signal end, and a second electrode of the fifth transistor is connected to the driving sub-circuit.

8. The OLED pixel circuit according to claim 1, wherein, the light-emitting control sub-circuit comprises a sixth transistor and a seventh transistor, wherein

a gate electrode of the sixth transistor is connected to the enable signal end, a first electrode of the sixth transistor is connected to the first voltage end, and a second electrode of the sixth transistor is connected to the driving sub-circuit;

and

a gate electrode of the seventh transistor is connected to the enable signal end, a first electrode of the seventh transistor is connected to the driving sub-circuit, and a second electrode of the seventh transistor is connected to the light emitting sub-circuit.

9. The OLED pixel circuit according to claim 1, wherein, the driving sub-circuit comprises a first transistor, a driving transistor and a reservoir capacitor;

the initialization and compensation sub-circuit comprises a second transistor, a third transistor and a fourth transistor;

the data writing sub-circuit comprises a fifth transistor;

the light-emitting control sub-circuit comprises a sixth transistor and a seventh transistor; and

the light emitting sub-circuit comprises a light-emitting device, wherein

a gate electrode of the fifth transistor is connected to the first signal end, a first electrode of the fifth transistor is connected to the second signal end, and a second electrode of the fifth transistor is connected to a first end of the reservoir capacitor;

a second end of the reservoir capacitor is connected to a first electrode of the driving transistor;

a gate electrode of the first transistor is connected to the third signal end, a first electrode of the first transistor is connected to the first end of the reservoir capacitor, and a second electrode of the first transistor is connected to a gate electrode of the driving transistor and a second electrode of the second transistor;

the gate electrode of the driving transistor is further connected the second electrode of the second transistor, the first electrode of the driving transistor is further connected to a second electrode of the sixth transistor, and a second electrode of the driving transistor is connected to a second electrode of the third transistor and a first electrode of the seventh transistor;

a gate electrode of the sixth transistor is connected to the enable signal end, and a first electrode of the sixth transistor is connected to the first voltage end;

a gate electrode of the seventh transistor is connected to the enable signal end, and a second electrode of the seventh transistor is connected to an anode of the light-emitting device;

a gate electrode of the second transistor is connected to the first signal end, and a first electrode of the second transistor is connected to the initial voltage end;

a gate electrode of the third transistor is connected to the first signal end, and a first electrode of the third transistor is connected to the initial voltage end;

a gate electrode of the fourth transistor is connected to the first signal end, a first electrode of the fourth transistor is connected to the initial voltage end, and a second electrode of the fourth transistor is connected to the anode of the light-emitting device; and

a cathode of the light-emitting device is connected to the second voltage end.

10. A display apparatus, comprising the OLED pixel circuit of claim 1, wherein, the OLED pixel circuit comprises:

an initialization and compensation sub-circuit, connected to a driving sub-circuit, a first signal end and an initial voltage end, and configured to initialize the driving sub-circuit and compensate a threshold voltage of the driving sub-circuit according to a signal input by the initial voltage end under control of a signal from the first signal end;

a data writing sub-circuit, connected to the driving sub-circuit, the first signal end and a second signal end, and configured to input a signal of the second signal end to the driving sub-circuit under control of a signal from the first signal end;

a light-emitting control sub-circuit, connected to the driving sub-circuit, a light emitting sub-circuit, an enable signal end and a first voltage end, and configured to input a signal of the first voltage end to the driving sub-circuit, and to input a driving signal output by the driving sub-circuit to the light emitting sub-circuit under control of a signal from the enable signal end;

the driving sub-circuit, further connected to a third signal end, and configured to output the driving signal under control of a signal from the third signal end and in a case of the signal of the first voltage end being input to the driving sub-circuit; and

a light emitting sub-circuit, further connected to a second voltage end, and configured to emit light under a driving of the second voltage end and the driving signal input by the light-emitting control sub-circuit.

11. A method for driving an OLED pixel circuit, comprising:

in a first phase of a frame, by a initialization and compensation sub-circuit, inputting a reset signal output via an initial voltage end to a driving sub-circuit, initializing the driving sub-circuit and compensating a threshold voltage of the driving sub-circuit under control of a signal from a first signal end;

inputting, by a data writing sub-circuit, a data signal output via a second signal end to the driving sub-circuit under control of the signal from the first signal end, to store the data signal into the driving sub-circuit;

in a second phase of the frame, inputting, by a light-emitting control sub-circuit, a supply voltage output via a first voltage end to the driving sub-circuit under control of a signal from an enable signal end;

outputting, by the driving sub-circuit, a driving signal under control of a signal from a third signal end;

inputting, by the light-emitting control sub-circuit, the driving signal output by the driving sub-circuit to a light emitting sub-circuit under control of a signal from the enable signal end; and

emitting light, by the light emitting sub-circuit under a driving of the driving signal input by the light-emitting control sub-circuit and a second voltage end.

12. The method according to claim 11, wherein, the driving sub-circuit comprises a first transistor, a driving transistor and a reservoir capacitor;

the initialization and compensation sub-circuit comprises a second transistor and a third transistor; and

the data writing sub-circuit comprises a fifth transistor, the method further comprises;

in the first phase of the frame,

inputting, via the first signal end, a turn-on signal to control the second transistor, the third transistor and the fifth transistor to be turned on;

inputting the reset signal output via the initial voltage end to the driving transistor via the second transistor, to initialize the driving transistor and compensate a threshold voltage of the driving transistor; and

inputting the data signal output via the second signal end to the reservoir capacitor via the fifth transistor and storing the same into the reservoir capacitor.

13. The method according to claim 12, wherein, the initialization and compensation sub-circuit further comprises a fourth transistor, in the first phase of the frame, the method further comprises:

Inputting, via the first signal end, a turn-on signal to control the fourth transistor to be turned on; and

inputting the reset signal output via the initial voltage end to the light emitting sub-circuit via the fourth transistor to initialize the light emitting sub-circuit.

14. The method according to claim 12, wherein, the light-emitting control sub-circuit comprises a sixth transistor and a seventh transistor, the method further comprises:

in the second phase of the frame,

inputting, via the third signal end, a turn-on signal to control the first transistor to be turned on; and

transmitting, by the reservoir capacitor, the data signal stored therein to a gate electrode of the driving transistor via the first transistor, to control the driving transistor to be turned on;

inputting, via the enable signal end, a turn-on signal to control the sixth transistor and the seventh transistor to be turned on;

inputting a supply voltage output via the first voltage end to the driving transistor via the sixth transistor;

outputting, by the driving transistor, the driving signal under control of the data signal and the supply voltage, and transmitting the driving signal to the light emitting sub-circuit via the seventh transistor; and

the light emitting sub-circuit emitting light under control of the driving signal and the supply voltage output by the second voltage end.

15. The method according to claim 14, wherein, in the second phase of the frame, the third signal end and the enable signal end input turn-on signals simultaneously;

or,

in a first sub-phase of the second phase of the frame, the third signal end inputs a turn-on signal; and

the reservoir capacitor transmits the data signal stored therein to the gate electrode of the driving transistor via the first transistor; and

in a second sub-phase of the second phase of the frame, while the third signal end inputs a turn-on signal continuously, the enable signal end inputs a turn-on signal.