Pixel circuit having threshold voltage compensation, driving method thereof, organic electroluminescent display panel, and display device

• US 10,192,487 B2
• Filed: 09/30/2016
• Issued: 01/29/2019
• Est. Priority Date: 01/06/2016
• Status: Active Grant

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: BOE Technology Group Co., Ltd.
• Inventors: Ma, Zhanjie
• Primary Examiner(s): Park, Sanghyuk
• Application Number:
  US15/520,210
• Publication Number:
  US 20180090071A1
• Time in Patent Office: 851 Days
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• 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 2300/0866 by means of changes in the pixel supply voltage
• 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: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 50/805 Electrodes

Abstract

A pixel circuit, a driving method, an organic electroluminescent display panel, and a display device, the pixel circuit includes a light emitting element, a driving control module, a resetting control module, a charging control module, a writing control module, and a light emitting control module; the resetting control module resets the first node and the light emitting element; the charging control module charges the second node through the light emitting control module and discharges the second node through the driving control module and the resetting control module; the writing control module writes a data signal to the second node; and the light emitting control module controls the driving control module to drive the light emitting element to emit light.

Claims

1. A pixel circuit, comprising a light emitting element, a driving control module, a resetting control module, a charging control module, a writing control module, and a light emitting control module, wherein:

a first control terminal and a second control terminal of the resetting control module are connected to a reset signal terminal, an input terminal of the resetting control module is connected to a first level signal terminal, a first output terminal of the resetting control module is connected to a first node, and a second output terminal of the resetting control module is connected to an output terminal of the driving control module and an input terminal of the light emitting element;

the resetting control module is configured to reset the first node and the light emitting element;

a control terminal of the charging control module is connected to the reset signal terminal, an input terminal of the charging control module is connected to an output terminal of the light emitting control module and a first input terminal of the driving control module, and an output terminal of the charging control module is connected to a second node;

the charging control module is configured to charge the second node through the light emitting control module and discharge the second node through the driving control module and the resetting control module;

a control terminal of the writing control module is connected to a scan signal terminal, an input terminal of the writing control module is connected to a data signal terminal, and an output terminal of the writing control module is connected to the second node;

the writing control module is configured to write a data signal to the second node;

a control terminal of the light emitting control module is connected to a light emitting signal terminal, and an input terminal of the light emitting control module is connected to a second level signal terminal;

the light emitting control module is configured to control the driving control module to drive the light emitting element to emit light;

a second input terminal of the driving control module is connected to the first node, and a third input terminal of the driving control module is connected to the second node; and

an output terminal of the light emitting element is connected to a third level signal terminal,

wherein the driving control module comprises a driving transistor having a gate connected to the first node, a first electrode connected to the input terminal of the charging control module and the output terminal of the light emitting control module, a second electrode connected to the input terminal of the light emitting element and the second output terminal of the resetting control module without intervention of any transistor.

2. The pixel circuit according to claim 1, wherein the driving control module further comprises a first capacitor connected between the first node and the second node.

3. The pixel circuit according to claim 2, wherein the driving control module further comprises a second capacitor;

one terminal of the second capacitor is connected to the second node and the other terminal of the second capacitor is connected to the second level signal terminal.

4. The pixel circuit according to claim 2, wherein the resetting control module comprises a first switching transistor and a second switching transistor;

a gate of the first switching transistor is connected to the reset signal terminal, a first electrode of the first switching transistor is connected to the first level signal terminal and a first electrode of the second switching transistor, and a second electrode of the first switching transistor is connected to the first node;

a gate of the second switching transistor is connected to the reset signal terminal, and a second electrode of the second switching transistor is connected to the second electrode of the driving transistor and the input terminal of the light emitting element.

5. The pixel circuit according to claim 2, wherein the charging control module comprises a third switching transistor;

a gate of the third switching transistor is connected to the reset signal terminal, a first electrode of the third switching transistor is connected to the first electrode of the driving transistor and the output terminal of the light emitting control module, and a second electrode of the third switching transistor is connected to the second node.

6. The pixel circuit according to claim 5, wherein the light emitting control module comprises a fifth switching transistor;

a gate of the fifth switching transistor is connected to the light emitting signal terminal, a first electrode of the fifth switching transistor is connected to the second level signal terminal, and a second electrode of the fifth switching transistor is connected to the first electrode of the third switching transistor and the first electrode of the driving transistor.

7. The pixel circuit according to claim 1, wherein the writing control module comprises a fourth switching transistor;

a gate of the fourth switching transistor is connected to the scan signal terminal, a first electrode of the fourth switching transistor is connected to the data signal terminal, and a second electrode of the fourth switching transistor is connected to the second node.

8. The pixel circuit according to claim 1, wherein an absolute value of a difference between a first level signal inputted from the first level signal terminal and a third level signal inputted from the third level signal terminal is smaller than a turn-on voltage of the light emitting element.

9. An organic electroluminescent display panel, comprising the pixel circuit according to claim 1.

10. A display device, comprising the organic electroluminescent display panel according to claim 9.

11. The organic electroluminescent display panel according to claim 9, wherein the driving control module further comprise a first capacitor connected between the first node and the second node.

12. The organic electroluminescent display panel according to claim 11, wherein the driving control module further comprises a second capacitor;

one terminal of the second capacitor is connected to the second node and the other terminal of the second capacitor is connected to the second level signal terminal.

13. The organic electroluminescent display panel according to claim 11, wherein the resetting control module comprises a first switching transistor and a second switching transistor;

a gate of the first switching transistor is connected to the reset signal terminal, a first electrode of the first switching transistor is connected to the first level signal terminal and a first electrode of the second switching transistor, and a second electrode of the first switching transistor is connected to the first node;

a gate of the second switching transistor is connected to the reset signal terminal, and a second electrode of the second switching transistor is connected to the second electrode of the driving transistor and the input terminal of the light emitting element.

14. The organic electroluminescent display panel according to claim 11, wherein the charging control module comprises a third switching transistor;

a gate of the third switching transistor is connected to the reset signal terminal, a first electrode of the third switching transistor is connected to the first electrode of the driving transistor and the output terminal of the light emitting control module, and a second electrode of the third switching transistor is connected to the second node.

15. The organic electroluminescent display panel according to claim 14, wherein the light emitting control module comprises a fifth switching transistor;

a gate of the fifth switching transistor is connected to the light emitting signal terminal, a first electrode of the fifth switching transistor is connected to the second level signal terminal, and a second electrode of the fifth switching transistor is connected to the first electrode of the third switching transistor and the first electrode of the driving transistor.

16. The organic electroluminescent display panel according to claim 9, wherein the writing control module comprises a fourth switching transistor;

a gate of the fourth switching transistor is connected to the scan signal terminal, a first electrode of the fourth switching transistor is connected to the data signal terminal, and a second electrode of the fourth switching transistor is connected to the second node.

17. The organic electroluminescent display panel according to claim 9, wherein an absolute value of a difference between a first level signal inputted from the first level signal terminal and a third level signal inputted from the third level signal terminal is smaller than a turn-on voltage of the light emitting element.

18. A driving method for the pixel circuit according to claim 1, comprising:

in a reset period, making the resetting control module in a turned-on status under control of the reset signal terminal, applying a signal at the first level signal terminal to the first node and the light emitting element, so as to reset the first node and the light emitting element;

making the charging control module in a turned-on status under control of the reset signal terminal, and making the light emitting control module in a turned-on status under control of the light emitting signal terminal, applying a signal at the second level signal terminal to the second node so as to charge the second node;

in a compensation period, making the charging control module in a turned-on status under control of the reset signal terminal, applying a signal at the second node to the first input terminal of the driving control module;

making the resetting control module in a turned-on status under control of the reset signal terminal, applying the signal at the first level signal terminal to the output terminal of the driving control module, and discharging the second node by the signal at the first level signal terminal;

in a writing period, making the writing control module in a turned-on status under control of the scan signal terminal, applying a data signal at the data signal terminal to the second node so as to write the data signal at the data signal terminal to the second node; and

in a light emitting period, making the light emitting control module in a turned-on status under control of the light emitting signal terminal, applying the signal at the second level signal terminal to the driving control module, and controlling the driving control module to drive the light emitting element to emit light by the signal at the second level signal terminal.