Pixel circuit and driving method thereof, display device

• US 10,991,307 B2
• Filed: 01/14/2019
• Issued: 04/27/2021
• Est. Priority Date: 05/25/2018
• Status: Active Grant

• Current Assignee: Beijing BOE Display Technology Co Ltd (BOE Technology Group Co., Ltd.), BOE Technology Group Co., Ltd.
• Original Assignee: Beijing BOE Display Technology Co Ltd (BOE Technology Group Co., Ltd.)
• Inventors: Wang, Zheng
• Primary Examiner(s): Leiby, Christopher E
• Application Number:
  US16/488,342
• Publication Number:
  US 20200402463A1
• Time in Patent Office: 834 Days
• CPC Class Codes: G09G 2300/0443 with several sub-pixels for the same colour in a pixel, not specifically used to display gradations G09G3/364 takes precedence
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 3/2007 Display of intermediate tones
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/2074 using sub-pixels
• 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

Abstract

The present disclosure provides a pixel circuit and a driving method thereof, and a display device. The pixel circuit includes: a data switching circuit configured to transmit a data voltage signal received from a data line in response to an on-signal; a data storage circuit configured to store the data voltage signal and output a first voltage and a second voltage according to the data voltage signal, wherein the first voltage is lower than the second voltage; a first light emitting circuit configured to emit light when turned on by a voltage difference between the first voltage and a power supply voltage; and a second light emitting circuit configured to emit light when turned on by a voltage difference between the second voltage and the power supply voltage.

Claims

1. A pixel circuit, comprising:

a data switching circuit configured to transmit a data voltage signal received from a data line in response to an on-signal from a control line;

a data storage circuit configured to store the data voltage signal received from the data switching circuit and output a first voltage and a second voltage according to the data voltage signal, wherein the first voltage is lower than the second voltage;

a first light emitting circuit disposed between a power supply voltage terminal and a ground terminal, and configured to emit light in a case where the first light emitting circuit is turned on by a voltage difference between the first voltage and a power supply voltage; and

a second light emitting circuit disposed between the power supply voltage terminal and the ground terminal and connected in parallel with the first light emitting circuit, and configured to emit light in a case where the second light emitting circuit is turned on by a voltage difference between the second voltage and the power supply voltage,

wherein the data storage circuit comprises a first capacitor and a second capacitor, and wherein a first terminal of the first capacitor is electrically connected to the data switching circuit and the second light emitting circuit, a second terminal of the first capacitor is directly connected to a first terminal of the second capacitor, the first terminal of the second capacitor is directly connected to the first light emitting circuit, and a second terminal of the second capacitor is directly connected to the ground terminal; and

the first light emitting circuit and the second light emitting circuit together serve as a light emitting circuit of a pixel structure.

2. The pixel circuit according to claim 1, wherein

the first light emitting circuit comprises a first driving transistor and a first light emitting device, wherein

a first terminal of the first driving transistor is electrically connected to the power supply voltage terminal, a second terminal of the first driving transistor is electrically connected to a first terminal of the first light emitting device, a control terminal of the first driving transistor is configured to receive the first voltage, and a second terminal of the first light emitting device is electrically connected to the ground terminal;

the second light emitting circuit comprises a second driving transistor and a second light emitting device, wherein

a first terminal of the second driving transistor is electrically connected to the power supply voltage terminal, a second terminal of the second driving transistor is electrically connected to a first terminal of the second light emitting device, a control terminal of the second driving transistor is configured to receive the second voltage, and a second terminal of the second light emitting device is electrically connected to the ground terminal.

3. A display device, comprising:

an array circuit comprising a plurality of pixel circuits according to claim 1.

4. The pixel circuit according to claim 2, wherein

both of the first driving transistor and the second driving transistor are NMOS transistors;

the first driving transistor is configured to make the first light emitting circuit does not emit light in a case where the data voltage signal is less than a first threshold; and

the second driving transistor is configured to make the second light emitting circuit emit light in the case where the data voltage signal is less than the first threshold.

5. The pixel circuit according to claim 4, wherein

the first driving transistor is further configured to make the first light emitting circuit emit light in a case where the data voltage signal is greater than or equal to the first threshold;

and

the second driving transistor is further configured to make the second light emitting circuit emit light in the case where the data voltage signal is greater than or equal to the first threshold.

6. The pixel circuit according to claim 2, wherein

both of the first driving transistor and the second driving transistor are PMOS transistors;

the first driving transistor is configured to make the first light emitting circuit does not emit light in a case where the data voltage signal is greater than a second threshold; and

the second driving transistor is configured to make the second light emitting circuit emit light in the case where the data voltage signal is greater than the second threshold.

7. The pixel circuit according to claim 6, wherein

the first driving transistor is further configured to make the first light emitting circuit emit light in a case where the data voltage signal is less than or equal to the second threshold;

and

the second driving transistor is further configured to make the second light emitting circuit emit light in the case where the data voltage signal is less than or equal to the second threshold.

8. The pixel circuit according to claim 2, wherein

an area of the first light emitting device is greater than an area of the second light emitting device.

9. The pixel circuit according to claim 2, wherein the data storage circuit further comprises:

a third capacitor or a diode disposed between the data switching circuit and the first capacitor.

10. The pixel circuit according to claim 9, further comprising:

an initialization circuit electrically connected to the ground terminal, and configured to raise a voltage of the first terminal of the first capacitor and a voltage of the first terminal of the second capacitor to a fixed voltage to perform an initialization process in response to an initialization signal and in a case where a voltage of the ground terminal is raised.

11. The pixel circuit according to claim 10, wherein the initialization circuit comprises:

a first switching transistor, of which a first terminal is electrically connected to the first terminal of the first capacitor, a second terminal is electrically connected to the second terminal of the first capacitor, and a control terminal is configured to receive the initialization signal; and

a second switching transistor, of which a first terminal is electrically connected to the first terminal of the second capacitor, a second terminal is electrically connected to the ground terminal, and a control terminal is configured to receive the initialization signal.

12. The pixel circuit according to claim 11, wherein the initialization circuit further comprises:

a third switching transistor, of which a first terminal is electrically connected to the data switching circuit, a second terminal is electrically connected to the first terminal of the first capacitor, and a control terminal is configured to receive the initialization signal.

13. The pixel circuit according to claim 12, wherein

the first light emitting circuit further comprises:

a fourth switching transistor, of which a first terminal is electrically connected to the control terminal of the first driving transistor, a second terminal is electrically connected to the second terminal of the first driving transistor, and a control terminal is configured to receive a first strobe signal;

the second light emitting circuit further comprises;

a fifth switching transistor, of which a first terminal is electrically connected to the control terminal of the second driving transistor, a second terminal is electrically connected to the second terminal of the second driving transistor, and a control terminal is configured to receive a second strobe signal;

wherein the first driving transistor and the second driving transistor are configured to discharge to the power supply voltage terminal respectively, in a case where the power supply voltage is lowered, the fourth switching transistor receives the first strobe signal, and the fifth switching transistor receives the second strobe signal.

14. The pixel circuit according to claim 13, wherein the data switching circuit comprises:

a sixth switching transistor, of which a first terminal is electrically connected to the data line, a second terminal is electrically connected to the data storage circuit, and a control terminal is connected to the control line.

15. The pixel circuit according to claim 2, wherein

the first light emitting circuit further comprises:

a fourth switching transistor, of which a first terminal is electrically connected to the control terminal of the first driving transistor, a second terminal is electrically connected to the second terminal of the first driving transistor, and a control terminal is configured to receive a first strobe signal;

the second light emitting circuit further comprises;

a fifth switching transistor, of which a first terminal is electrically connected to the control terminal of the second driving transistor, a second terminal is electrically connected to the second terminal of the second driving transistor, and a control terminal is configured to receive a second strobe signal;

wherein the first driving transistor and the second driving transistor are configured to discharge to the power supply voltage terminal respectively, in a case where the power supply voltage is lowered, the fourth switching transistor receives the first strobe signal, and the fifth switching transistor receives the second strobe signal.

16. A driving method for a pixel circuit, the pixel circuit comprising a data switching circuit, a data storage circuit, a first light emitting circuit, and a second light emitting circuit, wherein the data storage circuit comprises a first capacitor and a second capacitor, and wherein a first terminal of the first capacitor is electrically connected to the data switching circuit and the second light emitting circuit, a second terminal of the first capacitor is directly connected to a first terminal of the second capacitor, the first terminal of the second capacitor is directly connected to the first light emitting circuit, and a second terminal of the second capacitor is directly connected to the ground terminal;

and the first light emitting circuit and the second light emitting circuit together serve as a light emitting circuit of a pixel structure;

the driving method comprising;

transmitting a data voltage signal to the data storage circuit by the data switching circuit; and

storing the data voltage signal, outputting a first voltage to the first light emitting circuit and outputting a second voltage to the second light emitting circuit according to the data voltage signal by the data storage circuit, such that the first light emitting circuit emits light in a case where the first light emitting circuit is turned on by a voltage difference between the first voltage and a power supply voltage, and the second light emitting circuit emits light in a case where the second light emitting circuit is turned on by a voltage difference between the second voltage and the power supply voltage, wherein the first voltage is lower than the second voltage.

17. The driving method according to claim 16, wherein the pixel circuit further comprises an initialization circuit electrically connected to a ground terminal;

and

before the data voltage signal is transmitted to the data storage circuit, the driving method further comprises;

applying an initialization signal to the initialization circuit, raising a voltage of the ground terminal, and lowering the power supply voltage.

18. The driving method according to claim 17, wherein

the first light emitting circuit comprises a first driving transistor, a first light emitting device, and a fourth switching transistor, a first terminal of the first driving transistor being electrically connected to a power supply voltage terminal, a second terminal of the first driving transistor being electrically connected to a first terminal of the first light emitting device, a control terminal of the first driving transistor being configured to receive the first voltage, a second terminal of the first light emitting device being electrically connected to the ground terminal, a first terminal of the fourth switching transistor being electrically connected to the control terminal of the first driving transistor, a second terminal of the fourth switching transistor being electrically connected to the second terminal of the first driving transistor, and a control terminal of the fourth switching transistor being configured to receive a first strobe signal;

the second light emitting circuit comprises a second driving transistor, a second light emitting device, and a fifth switching transistor, a first terminal of the second driving transistor being electrically connected to the power supply voltage terminal, a second terminal of the second driving transistor being electrically connected to a first terminal of the second light emitting device, a control terminal of the second driving transistor being configured to receive the second voltage, a second terminal of the second light emitting device being electrically connected to the ground terminal, a first terminal of the fifth switching transistor being electrically connected to the control terminal of the second driving transistor, a second terminal of the fifth switching transistor being electrically connected to the second terminal of the second driving transistor, and a control terminal of the fifth switching transistor being configured to receive a second strobe signal; and

after the initialization signal is applied to the initialization circuit and before the data voltage signal is transmitted to the data storage circuit, the driving method further comprises;

in a case where the power supply voltage is lowered, applying the first strobe signal to the fourth switching transistor and applying the second strobe signal to the fifth switching transistor such that the first driving transistor and the second driving transistor discharge to the power supply voltage terminal respectively.