Pixel circuit, driving method thereof, display panel and display device

Patent metadata

Field	Value
Publication number	US-11062652-B1
Application number	US-202016860254-A
Country	US
Kind code	B1
Filing date	Apr 28, 2020
Priority date	Jan 2, 2020
Publication date	Jul 13, 2021
Grant date	Jul 13, 2021

Abstract

Disclosed are a pixel circuit, a driving method, a display panel and a display device. A data writing module of the pixel circuit supplies a data signal to a gate electrode of a drive transistor and a first plate of a storage capacitor in a data writing phase. A reset module of the pixel circuit supplies a reset signal to a second plate of the storage capacitor in a data writing phase. A threshold compensation module of the pixel circuit supplies a threshold compensation signal to the second plate of the storage capacitor in a threshold compensation phase, and accordingly a potential of the first plate of the storage capacitor is adjusted to a first potential, and the drive transistor is threshold compensated. The threshold compensation signal is greater than the reset signal. A drive transistor supplies a drive current to an organic light-emitting element in a light emission phase to drive the organic light-emitting element to emit light.

First claim

What is claimed is:

1. A pixel circuit comprising:
a drive transistor,
a storage capacitor,
a data writing module,
a reset module,
a threshold compensation module, and
an organic light-emitting element,
wherein the data writing module is electrically connected to a gate electrode of the drive transistor and a first plate of the storage capacitor, and configured to write a data signal to the gate electrode of the drive transistor and the first plate of the storage capacitor in a data writing phase;
wherein the reset module is electrically connected to a second plate of the storage capacitor, and configured to write a reset signal to the second plate of the storage capacitor in the data writing phase;
wherein the threshold compensation module is electrically connected to the second plate of the storage capacitor, and configured to write a threshold compensation signal to the second plate of the storage capacitor in a threshold compensation phase to adjust a potential of the first plate of the storage capacitor to a first potential to perform threshold compensate on the drive transistor, wherein the threshold compensation signal is greater than the reset signal; and
wherein the drive transistor is electrically connected to the organic light-emitting element, and configured to provide a drive current to the organic light-emitting element in a light emission phase to drive the organic light-emitting element to emit light.

2. The pixel circuit of claim 1 , wherein the threshold compensation module comprises a first transistor; and a threshold voltage of the first transistor is a first threshold voltage; and
wherein the threshold compensation signal comprises the first threshold voltage.

3. The pixel circuit of claim 2 , wherein a threshold voltage of the drive transistor is a second threshold voltage; and
wherein a difference between the first threshold voltage and the second threshold voltage is within a preset range.

4. The pixel circuit of claim 3 , wherein an active layer of the first transistor comprises a first channel and an active layer of the drive transistor comprises a second channel; and
wherein a distance W between the first channel and the second channel satisfies: 2.5 μm≤W≤4.5 μm.

5. The pixel circuit of claim 1 , wherein the threshold compensation module comprises a first transistor, the data writing module comprises a second transistor, and the reset module comprises a third transistor;
wherein a first electrode of the first transistor is connected to an anode of the organic light-emitting element, and a second electrode of the first transistor and a gate electrode of the first transistor are both electrically connected to the second plate of the storage capacitor;
wherein a first electrode of the third transistor receives the reset signal, a second electrode of the third transistor is electrically connected to the second plate of the storage capacitor, and a gate electrode of the third transistor receives a first scanning signal;
wherein a first electrode of the second transistor receives a data signal, a second electrode of the second transistor is electrically connected to the gate electrode of the drive transistor and the first plate of the storage capacitor, and a gate electrode of the second transistor receives the first scanning signal; and
wherein a first electrode of the drive transistor receives a power signal, a second electrode of the drive transistor is electrically connected to the anode of the organic light-emitting element, and a cathode of the organic light-emitting element receives a low-level signal.

6. The pixel circuit of claim 5 , further comprising a connect wire, wherein the first transistor, the second transistor and the third transistor are electrically connected to the storage capacitor through different connect wires;
wherein a width L 1 of the connect wire satisfies: 1.5 μm≤L 1 ≤2.5 μm;
wherein a maximum extension length of a vertical projection of the first transistor on a reference plane is L 2 , wherein L 2 ≤3 μm, wherein the reference plane is parallel to a plane of an active layer of the first transistor;
wherein a maximum extension length of a vertical projection of the second transistor on the reference plane is L 3 , wherein L 3 ≤3 μm; and
wherein a maximum extension length of a vertical projection of the third transistor on the reference plane is L 4 , wherein L 4 ≤3 μm.

7. The pixel circuit of claim 1 , wherein the first plate or the second plate of the storage capacitor also serves as the gate electrode of the drive transistor.

8. A method for driving a pixel circuit, the pixel circuit comprising a drive transistor, a storage capacitor, a data writing module, a reset module, a threshold compensation module and an organic light-emitting element, the method comprising:
in a data writing phase, writing, by the data writing module, a data signal to a gate electrode of the drive transistor and a first plate of the storage capacitor, and writing, by the reset module, a reset signal to a second plate of the storage capacitor so that a potential of the second plate of the storage capacitor is equal to a potential of the reset signal;
in a threshold compensation phase, writing, by the threshold compensation module, a threshold compensation signal to the second plate of the storage capacitor so that the potential of the second plate of the storage capacitor is equal to a potential of the threshold compensation signal and the drive transistor is threshold compensated, wherein the threshold compensation signal is greater than the reset signal; and
in a light emission phase, providing, by the drive transistor, a drive current to the organic light-emitting element to drive the organic light-emitting element to emit light.

9. The method of claim 8 , wherein the threshold compensation module comprises a first transistor, the data writing module comprises a second transistor, and the reset module comprises a third transistor;
wherein a first electrode of the first transistor is connected to an anode of the organic light-emitting element, and a second electrode of the first transistor and a gate electrode of the first transistor are both electrically connected to the second plate of the storage capacitor;
wherein a first electrode of the third transistor receives the reset signal, a second electrode of the third transistor is electrically connected to the second plate of the storage capacitor, and a gate electrode of the third transistor receives a first scanning signal;
wherein a first electrode of the second transistor receives the data signal, a second electrode of the second transistor is electrically connected to the gate electrode of the drive transistor and the first plate of the storage capacitor, and a gate electrode of the second transistor receives the first scanning signal;
wherein a first electrode of the drive transistor receives a power signal, a second electrode of the drive transistor is electrically connected to the anode of the organic light-emitting element, and a cathode of the organic light-emitting element receives a low-level signal;
wherein the data writing phase comprises a first phase and a second phase;
wherein in the first phase, the second transistor and the third transistor are switched on, and the data signal is written to the gate electrode of the drive transistor and the first plate of the storage capacitor through the second transistor to initialize the gate electrode of the drive transistor and a first electrode of the storage capacitor, and the reset signal is written to the second plate of the storage capacitor and the gate electrode of the first transistor through the third transistor to initialize the second plate of the storage capa

Assignees

• Wuhan Tianma Micro Electronics Co Ltd

Inventors

• Zhou Maoqing
• Chen Fei
• Xiang Dongxu

Classifications

• G09G2354/00

  Aspects of interface with display user · CPC title

• G09G2300/0465

  Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness · CPC title

• G09G3/3233 Primary

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

• G09G2320/045

  Compensation of drifts in the characteristics of light emitting or modulating elements · 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