PIXEL CIRCUIT, ORGANIC LIGHT EMITTING DISPLAY PANEL AND DISPLAY APPARATUS

• US 20160275860A1
• Filed: 11/07/2014
• Published: 09/22/2016
• Est. Priority Date: 08/22/2014
• Status: Active Grant

• Current Assignee: Beijing BOE Optoelectronics Technology Co Ltd. (BOE Technology Group Co., Ltd.), BOE Technology Group Co., Ltd.
• Original Assignee: Beijing BOE Optoelectronics Technology Co Ltd. (BOE Technology Group Co., Ltd.), BOE Technology Group Co., Ltd.
• Inventors: WU, Hao
• Granted Patent: US 9,711,085 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2330/12 Test circuits or failure detection circuits included in a display system, as permanent part thereof
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• 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

There are provided a pixel circuit, an organic light emitting display panel and a display apparatus. The pixel circuit comprises: a light emitting device (01), a charging module (02), a driving module (03), and a testing module (04); an input terminal of the charging module (02) is connected to a data signal terminal (Data), a control terminal thereof is connected to a scan signal terminal (Gate), and an output terminal thereof is connected to a first input terminal (al) and a first output terminal (b1) of the testing module (04) respectively; a control terminal of the driving module (03) is connected to a second output terminal (b2) of the testing module (04), an input terminal thereof is connected to a first reference signal terminal (Ref1), and an output terminal thereof is connected to an input terminal of the light emitting device (01); and a control terminal of the testing module (04) is connected to a test signal terminal (TEST), a second input terminal (a2) thereof is connected to an output terminal of the light emitting device (01), and a third output terminal (b3) thereof is connected to a second reference signal terminal (Ref2), wherein the testing signal terminal (TEST) is used to provide a test signal switching between a displaying period of time and a testing period of time. The pixel circuit is capable of realizing that a current signal for driving the light emitting device (01) to emit light reaches the uniformity standard so that display luminance of pixels is uniform and quality of a display picture is ensured.

Claims

1. A pixel circuit, comprising:

a light emitting device, a charging module, a driving module, and a testing module;

wherein an input terminal of the charging module is connected to a data signal terminal, a control terminal thereof is connected to a scan signal terminal, and an output terminal thereof is connected to a first input terminal and a first output terminal of the testing module respectively;

a control terminal of the driving module is connected to a second output terminal of the testing module, an input terminal thereof is connected to a first reference signal terminal, and an output terminal thereof is connected to an input terminal of the light emitting device; and

a control terminal of the testing module is connected to a test signal terminal, a second input terminal thereof is connected to an output terminal of the light emitting device, and a third output terminal thereof is connected to a second reference signal terminal,

wherein the testing signal terminal is used to provide a test signal switching between a displaying period of time and a testing period of time.

2. The pixel circuit according to claim 1, wherein during the displaying period of time, the testing module is configured to connect the output terminal of the charging module with the control terminal of the driving module, and connect the second reference signal terminal with the output terminal of the light emitting device, so that the charging module provides a driving voltage signal to the driving module under the control of the scan signal terminal, and the driving module drives the light emitting device to emit light under the control of the driving voltage signal.

3. The pixel circuit according to claim 1, wherein during the testing period of time, the testing module is configured to connect the output terminal of the light emitting device with the output terminal of the charging module, so that the charging module outputs a current signal of the light emitting device to the data signal terminal under the control of the scan signal terminal.

4. The pixel circuit according to claim 3, wherein the testing module comprises:

a first switching transistor, and a second switching transistor and a third switching transistor which have a same doping polarity;

and the first switching transistor has a doping polarity inverse to the second switching transistor and the third switching transistor respectively;

wherein a gate of the first switching transistor, a gate of the second switching transistor and a gate of the third switching transistor are connected to the test signal terminal respectively;

a source of the first switching transistor and a source of the third switching transistor are connected to the output terminal of the light emitting device respectively;

a drain of the first switching transistor and a source of the second switching transistor are connected to the output terminal of the charging module;

a drain of the second switching transistor is connected to the control terminal of the driving module; and

a drain of the third switching transistor is connected to the second reference signal terminal.

5. The pixel circuit according to claim 4, wherein the first switching transistor is an N type transistor, while the second switching transistor and the third switching transistors are P type transistors;

or

the first switching transistor is the P type transistor, while the second switching transistor and the third switching transistor are N type transistors.

6. The pixel circuit according to claim 4, wherein the charging module comprises:

a fourth switching transistor;

wherein a gate of the fourth switching transistor is connected to the scan signal terminal, a source thereof is connected to the data signal terminal, and a drain thereof is connected to the first input terminal and the first output terminal of the testing module.

7. The pixel circuit according to claim 4, wherein the driving module comprises:

a storage capacitor and a fifth switching transistor;

a source of the fifth switching transistor is connected to the first reference signal terminal, a gate thereof is connected to the second output terminal of the testing module, and a drain thereof is connected to the input terminal of the light emitting device;

when the fifth switching transistor is the P type transistor, the storage capacitor is connected in parallel between the source and the gate of the fifth switching transistor; and

when the fifth switching transistor is the N type transistor, the storage capacitor is connected in parallel between the drain and the gate of the fifth switching transistor.

8. An organic light emitting display panel, comprising a plurality of the pixel circuits according to claim 1 arranged in array.

9. A display apparatus, comprising the organic light emitting display panel according to claim 8.

10. The display apparatus according to claim 9, further comprising:

a test controlling unit connected to a test signal terminal through a test signal line, and a compensation processing unit and a driving unit connected to a data signal terminal through a data line;

wherein the test controlling unit is configured to provide a test signal switching between a displaying period of time and a testing period of time to the test signal terminal;

the compensation processing unit is configured to determine a compensation voltage signal for the respective pixel circuits according to a current signal received from the data signal terminal during the testing period of time and transmit the compensation voltage signal to the driving unit; and

the driving unit is configured to superpose the compensation voltage signal transmitted by the compensation processing unit and a data signal received from a signal source and then transmit the superposed signals to the data signal terminal.

11. The display apparatus according to claim 10, wherein the compensation processing unit and the driving unit are integrated on a same chip.

12. The pixel circuit according to claim 2, wherein during the testing period of time, the testing module is configured to connect the output terminal of the light emitting device with the output terminal of the charging module, so that the charging module outputs a current signal of the light emitting device to the data signal terminal under the control of the scan signal terminal.

13. The pixel circuit according to claim 2, wherein the testing module comprises:

a first switching transistor, and a second switching transistor and a third switching transistor which have a same doping polarity; and

the first switching transistor has a doping polarity inverse to the second switching transistor and the third switching transistor respectively;

wherein a gate of the first switching transistor, a gate of the second switching transistor and a gate of the third switching transistor are connected to the test signal terminal respectively;

a source of the first switching transistor and a source of the third switching transistor are connected to the output terminal of the light emitting device respectively;

a drain of the first switching transistor and a source of the second switching transistor are connected to the output terminal of the charging module;

a drain of the second switching transistor is connected to the control terminal of the driving module; and

a drain of the third switching transistor is connected to the second reference signal terminal.

14. The pixel circuit according to claim 3, wherein the testing module comprises:

a first switching transistor, and a second switching transistor and a third switching transistor which have a same doping polarity; and

the first switching transistor has a doping polarity inverse to the second switching transistor and the third switching transistor respectively;

wherein a gate of the first switching transistor, a gate of the second switching transistor and a gate of the third switching transistor are connected to the test signal terminal respectively;

a source of the first switching transistor and a source of the third switching transistor are connected to the output terminal of the light emitting device respectively;

a drain of the first switching transistor and a source of the second switching transistor are connected to the output terminal of the charging module;

a drain of the second switching transistor is connected to the control terminal of the driving module; and

a drain of the third switching transistor is connected to the second reference signal terminal.

15. The OLED panel according to claim 8, wherein during the displaying period of time, the testing module is configured to connect the output terminal of the charging module with the control terminal of the driving module, and connect the second reference signal terminal with the output terminal of the light emitting device, so that the charging module provides a driving voltage signal to the driving module under the control of the scan signal terminal, and the driving module drives the light emitting device to emit light under the control of the driving voltage signal.

16. The OLED panel according to claim 8, wherein during the testing period of time, the testing module is configured to connect the output terminal of the light emitting device with the output terminal of the charging module, so that the charging module outputs a current signal of the light emitting device to the data signal terminal under the control of the scan signal terminal.

17. The OLED panel according to claim 8, wherein the testing module comprises:

a first switching transistor, and a second switching transistor and a third switching transistor which have a same doping polarity; and

the first switching transistor has a doping polarity inverse to the second switching transistor and the third switching transistor respectively;

wherein a gate of the first switching transistor, a gate of the second switching transistor and a gate of the third switching transistor are connected to the test signal terminal respectively;

a source of the first switching transistor and a source of the third switching transistor are connected to the output terminal of the light emitting device respectively;

a drain of the first switching transistor and a source of the second switching transistor are connected to the output terminal of the charging module;

a drain of the second switching transistor is connected to the control terminal of the driving module; and

a drain of the third switching transistor is connected to the second reference signal terminal.

18. The OLEO panel according to claim 17, wherein the first switching transistor is an N type transistor, while the second switching transistor and the third switching transistors are P type transistors;

or

the first switching transistor is the P type transistor, while the second switching transistor and the third switching transistor are N type transistors.

19. The OLEO panel according to claim 17, wherein the charging module comprises:

a fourth switching transistor;

wherein a gate of the fourth switching transistor is connected to the scan signal terminal, a source thereof is connected to the data signal terminal, and a drain thereof is connected to the first input terminal and the first output terminal of the testing module.

20. The OLEO panel according to claim 17, wherein the driving module comprises:

a storage capacitor and a fifth switching transistor;

a source of the fifth switching transistor is connected to the first reference signal terminal, a gate thereof is connected to the second output terminal of the testing module, and a drain thereof is connected to the input terminal of the light emitting device;

when the fifth switching transistor is the P type transistor, the storage capacitor is connected in parallel between the source and the gate of the fifth switching transistor; and

when the fifth switching transistor is the N type transistor, the storage capacitor is connected in parallel between the drain and the gate of the fifth switching transistor.