Pixel circuit and driving method thereof, display panel

• US 10,643,536 B2
• Filed: 06/14/2017
• Issued: 05/05/2020
• Est. Priority Date: 12/29/2016
• Status: Active Grant

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: BOE Technology Group Co., Ltd.
• Inventors: Yue, Han, Chen, Xiaochuan, Yang, Shengji, Liu, Dongni, Wang, Lei, Fu, Jie, Lu, Pengcheng, Xiao, Li
• Primary Examiner(s): Nguyen, Jennifer T
• Application Number:
  US15/744,476
• Publication Number:
  US 20190005881A1
• Time in Patent Office: 1,056 Days
• Field of Search: 345 76- 80, 345 98-100, 345690-691
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• 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 2330/10 Dealing with defective pixels
• 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 3/3208 organic, e.g. using organic light-emitting diodes [OLED]
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3241 the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror

Abstract

A pixel circuit and a driving method thereof, a display panel. The pixel circuit includes a driving circuit, a light emitting circuit and a short-circuit protection circuit. The short-circuit protection circuit is connected in series between the driving circuit and the light emitting circuit, and the short-circuit protection circuit is configured to obtain an input terminal signal of the light emitting circuit and disconnect or connect an input signal branch of the light emitting circuit according to the obtained input terminal signal of the light emitting circuit.

Claims

1. A pixel circuit, comprising:

a driving circuit,

a light emitting circuit having an input terminal and

a short-circuit protection circuit, wherein the short-circuit protection circuit is connected in series between the driving circuit and the light emitting circuit, and is configured to obtain an input terminal signal of the light emitting circuit and disconnect or connect an input signal branch of the light emitting circuit according to the input terminal signal of the light emitting circuit;

wherein the short-circuit protection circuit comprises;

a short circuit protection transistor and a signal control circuit,

the signal control circuit comprises an input terminal being connected to an input terminal of the light emitting circuit and an output terminal being directly connected to a control electrode of the short circuit protection transistor, and is configured to obtain the input terminal signal of the light emitting circuit and output a short circuit control signal; and

the short circuit protection transistor comprises a first electrode being connected to an output terminal of the driving circuit and a second electrode being connected to the input terminal of the light emitting circuit, and is configured to disconnect or connect the input signal branch of the light emitting circuit according to the short circuit control signal output by the signal control circuit;

a judgment control circuit comprising;

an input terminal being connected to the input terminal of the light emitting circuit and an output terminal being connected to the control electrode of the short circuit protection transistor, and is configured to obtain the input terminal signal of the light emitting circuit and output the short circuit control signal in a case that the light emitting circuit is in an operation stage;

wherein the judgment control circuit comprises a first judgment transistor having a control electrode, a first electrode and a second electrode and a second judgment transistor having a control electrode, a first electrode and a second electrode,

wherein the control electrode of the first judgment transistor is connected to an input terminal of the light emitting circuit, the first electrode of the first judgment transistor is connected to a first voltage signal, and the second electrode of the first judgment transistor is connected to a second electrode of the second judgment transistor;

wherein the control electrode of the second judgment transistor is connected to the input terminal of the light emitting circuit, the first electrode of the second judgment transistor is connected to a second voltage signal, and the second electrode of the second judgment transistor is connected to the control electrode of the short circuit protection transistor; and

wherein a type of the first judgment transistor and a type of the second judgment transistor are opposite.

2. The pixel circuit according to claim 1, wherein the signal control circuit further comprises a pre-charge circuit, the pre-charge circuit is connected in series between the judgment control circuit and the control electrode of the short circuit protection transistor, the pre-charge circuit is configured to control the short circuit protection transistor to be in a turned-on state in a case that the light emitting circuit is in a non-operation stage, and is further configured to transmit the short circuit control signal to the control electrode of the short circuit protection transistor in a case that the light emitting circuit is in the operation stage.

3. The pixel circuit according to claim 2, wherein the pre-charge circuit comprises a first pre-charge transistor, a second pre-charge transistor, a third pre-charge transistor and a pre-charge capacitor,

a control electrode of the first pre-charge transistor is connected to a first control signal terminal, a first electrode of the first pre-charge transistor is connected to a third voltage signal, and a second electrode of the first pre-charge transistor is connected to the control electrode of the short circuit protection transistor;

a control electrode of the second pre-charge transistor is connected to a second control signal terminal, a first electrode of the second pre-charge transistor is connected to a fourth voltage signal, and a second electrode of the second pre-charge transistor is connected to a second electrode of the third pre-charge transistor;

a control electrode of the third pre-charge transistor is connected to a third control signal terminal, and a first electrode of the third pre-charge transistor is connected to the output terminal of the judgment control circuit; and

a first terminal of the pre-charge capacitor is connected to the control electrode of the short circuit protection transistor, and a second terminal of the pre-charge capacitor is connected to the second electrode of the third pre-charge transistor.

4. The pixel circuit according to claim 2, further comprising a switch circuit, configured to transmit a data signal to a control terminal of the driving circuit in a case of the switch circuit being turned on.

5. The pixel circuit according to claim 2, wherein the light emitting circuit is an organic electroluminescent device, an anode of the organic electroluminescent device is connected to an input terminal of the short-circuit protection circuit, and a cathode of the organic electroluminescent device is connected to a ground terminal.

6. The pixel circuit according to claim 1, further comprising a switch circuit, configured to transmit a data signal to a control terminal of the driving circuit in a case of the switch circuit being turned on.

7. The pixel circuit according to claim 1, wherein the light emitting circuit is an organic electroluminescent device, an anode of the organic electroluminescent device is connected to an input terminal of the short-circuit protection circuit, and a cathode of the organic electroluminescent device is connected to a ground terminal.

8. A driving method used for a pixel circuit according to claim 1, comprising:

in an operation stage, inputting a data signal to a control terminal of the driving circuit, and outputting a light emitting signal corresponding to the data signal to the light emitting circuit through the driving circuit, the light emitting signal being the input terminal signal of the light emitting circuit;

wherein the operation stage comprises a short circuit detection stage; and

in the short circuit detection stage, the input terminal signal of the light emitting circuit is obtained through the short-circuit protection circuit, and the input signal branch of the light emitting circuit is disconnected or connected according to the input terminal signal of the light emitting circuit.

9. The driving method of the pixel circuit according to claim 8, wherein:

in the short circuit detection stage, a signal control circuit obtains the input terminal signal of the light emitting circuit and outputs a short circuit control signal, and a short circuit protection transistor disconnects or connects the input signal branch of the light emitting circuit according to the short circuit control signal output by the signal control circuit.

10. The driving method of the pixel circuit according to claim 9, further comprising:

in a non-operation stage, outputting a signal through a pre-charge circuit to turn on the short circuit protection transistor; and

in the short circuit detection stage, obtaining the input terminal signal of the light emitting circuit through a judgment control circuit, outputting the short circuit control signal, and transmitting the short circuit control signal to a control electrode of the short circuit protection transistor through the pre-charge circuit, so as to disconnect or connect the input signal branch of the light emitting circuit.

11. A display panel, comprising a pixel circuit according to claim 1.

12. The pixel circuit according to claim 1, further comprising a switch circuit, configured to transmit a data signal to a control terminal of the driving circuit in a case of the switch circuit being turned on.

13. The pixel circuit according to claim 1, wherein the light emitting circuit is an organic electroluminescent device, an anode of the organic electroluminescent device is connected to an input terminal of the short-circuit protection circuit, and a cathode of the organic electroluminescent device is connected to a ground terminal.

14. The pixel circuit according to claim 1, wherein the first judgment transistor is an N-type transistor, the second judgment transistor is a P-type transistor.

15. The pixel circuit according to claim 1, wherein the first judgment transistor is a P-type transistor, the second judgment transistor is an N-type transistor.