Pixel circuit, driving method thereof and display device

Patent metadata

Field	Value
Publication number	US-11488530-B2
Application number	US-202017261702-A
Country	US
Kind code	B2
Filing date	Sep 17, 2020
Priority date	Jul 15, 2020
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

The present application provides a pixel circuit, a driving method thereof and a display device. An anti-leakage transistor is added between the gate of the driving transistor and the initialization transistor and between the gate of the driving transistor and the compensation transistor. The anti-leakage transistor includes an active layer with oxide semiconductor. Low leakage property of a metal oxide transistor is utilized to suppress potential changes of the gate of the driving transistor during a light-emitting diode emits light.

First claim

The invention claimed is:

1. A pixel circuit, comprising:
a light-emitting diode;
a driving transistor, wherein a first end of the driving transistor is electrically connected to the light-emitting diode, a control end of the driving transistor is connected to a first node, and the driving transistor is configured to control operation state of the light-emitting diode based on a potential of the first node;
an anti-leakage transistor, wherein the first end of the anti-leakage transistor is connected to the first node, a second end of the anti-leakage transistor is connected to a second node, and the anti-leakage transistor comprises an active layer with oxide semiconductor and is in switched-off state when the light-emitting diode is in light-emitting state;
an initialization transistor, wherein the first end of the initialization transistor is connected to the second node, the second end of the initialization transistor is connected to an initialization signal line, and the initialization transistor is configured to transmit an initialization signal input from the initialization signal line to the first node;
a compensation transistor, wherein the first end of the compensation transistor is connected to the first end of the driving transistor, the second end of the compensation transistor is connected to the second node, and the compensation transistor is configured to enable the first end of the driving transistor and the control end of the driving transistor to be electrically connected; and
a restoration transistor, wherein the first end of the restoration transistor is connected to an anode of the light-emitting diode, the second end of the restoration transistor is connected to the first end of the initialization transistor and the second node, and the restoration transistor is configured to transmit the initialization signal to the anode of the light-emitting diode based on a third control signal, wherein the initialization transistor is configured to transmit the initialization signal to the second end of the restoration transistor and the first node based on the third control signal.

2. The pixel circuit according to claim 1 , wherein the anti-leakage transistor is configured to be in the switched-off state based on a first control signal when the light-emitting diode is in the light-emitting state, and
wherein the anti-leakage transistor is an N-type transistor and the initialization transistor is a P-type transistor.

3. The pixel circuit according to claim 1 , wherein the anti-leakage transistor is configured to be in the switched-off state based on a second control signal when the light-emitting diode is in the light-emitting state;
the initialization transistor is configured to transmit the initialization signal input from the initialization signal line to the first node based on the third control signal;
the compensation transistor is configured to enable the first end of the driving transistor and the control end of the driving transistor to be electrically connected based on a fourth control signal;
the second control signal, the third control signal, and the fourth control signal are different from each other.

4. The pixel circuit according to claim 1 , further comprising:
a switching transistor, wherein the first end of the switching transistor is connected to the second end of the driving transistor, the second end of the switching transistor is connected to a data signal line, and the switching transistor is configured to transmit a data signal input from the data signal line to the second end of the driving transistor based on a fourth control signal;
a first light-emitting control transistor, wherein the first end of the first light-emitting control transistor is connected to the second end of the driving transistor, the second end of the first light-emitting control transistor is connected to a power supply voltage signal line, the control end of the first light-emitting control transistor is connected to a light-emitting control signal line, and the first light-emitting control transistor is configured to transmit a power supply voltage input from the power supply voltage signal line to the second end of the drive transistor based on a light-emitting control signal at input from the light-emitting control signal line;
a second light-emitting control transistor, wherein the first end of the second light-emitting control transistor is connected to the first end of the driving transistor, the second end of the second light-emitting control transistor is connected to the anode of the light-emitting diode, the control end of the second light-emitting control transistor is connected to the light-emitting control signal line, and the second light-emitting control transistor is configured to transmit a driving current output from the driving transistor to the light-emitting diode based on the light-emitting control signal;
a storage capacitor, wherein the first end of the storage capacitor is connected to the first node, and the second end of the storage capacitor is connected to the power supply voltage signal line.

5. The pixel circuit according to claim 4 , wherein all the driving transistor, the switching transistor, the compensation transistor, the initialization transistor, the first light-emitting control transistor and the second light-emitting control transistor are P-type transistors having active layers with polysilicon.

6. A method for driving the pixel circuit according to claim 1 , comprising the steps of:
in initialization phase, switching on the anti-leakage transistor, and switching on the initialization transistor to transmit an initialization signal to the first node;
in threshold voltage compensating and data writing phase, switching on the anti-leakage transistor, and switching on the compensation transistor to enable the first end of the driving transistor and the control end of the driving transistor to be electrically connected;
in light-emitting phase, switching off the anti-leakage transistor, the compensation transistor and the initialization transistor, and switching on the driving transistor to control the light-emitting diode to be in the light-emitting state.

7. A display device, comprising:
a light-emitting diode;
a driving transistor, configured to transmit a driving current to the light-emitting diode;
an initialization transistor, configured to transmit an initialization signal to a control end of the driving transistor;
a compensation transistor, configured to transmit a data signal with a compensated threshold voltage to the control end of the driving transistor;
an anti-leakage transistor, connected between the control end of the driving transistor and the initialization transistor and connected between the control end of the driving transistor and the compensation transistor, wherein the anti-leakage transistor comprises an active layer with oxide semiconductor; and
a restoration transistor, a first end of the restoration transistor is connected to an anode of the light-emitting diode, a second end of the restoration transistor is connected to the first end of the initialization transistor, and the control end of the restoration transistor is configured to receive a third control signal, wherein the first end of the initialization transistor is connected to the second end of the restoration transistor, the control end of the initialization transistor is configured to receive the third control signal, and the second end of the initialization transistor is configured to receive the initialization signal.

8. The display device according to claim 7 , wherein the anti-leakage transistor is configured to be in switched-off state based on a first control signal, and
wherein the anti-leakage t

Assignees

• Wuhan China Star Optoelectronics Semiconductor Display Tech Co Ltd

Inventors

• Wang Xuanyun
• Cho Sunghwan
• Dai Chao

Classifications

• G09G3/3233 Primary

  with pixel circuitry controlling the current through the light-emitting element · CPC title

• G09G2300/0861

  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 title

• G09G2320/0247

  Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes · CPC title

• G09G2300/0819

  used for counteracting undesired variations, e.g. feedback or autozeroing · CPC title

• G09G2310/08

  Details of timing specific for flat panels, other than clock recovery · CPC title