Pixel driving circuit and operating method thereof

Patent metadata

Field	Value
Publication number	US-10878744-B2
Application number	US-201916683505-A
Country	US
Kind code	B2
Filing date	Nov 14, 2019
Priority date	Jan 15, 2019
Publication date	Dec 29, 2020
Grant date	Dec 29, 2020

Abstract

A pixel driving circuit utilizing a transistor having two gate ends as the driving unit for pixels of a display panel to provide a stable driving current to compensate for the variation of threshold voltages of transistors in different pixels and to improve the uniformity of the brightness of the display panel.

First claim

What is claimed is:

1. A pixel driving circuit, comprising:
a first transistor, comprising:
a first end, receiving a first supply voltage;
a second end;
a first gate end, receiving a first control signal and biasing the first transistor according to the first control signal;
a second gate end;

a capacitor, wherein one end of the capacitor is connected to the second gate end of the first transistor, and the other end is connected to the first end of the first transistor or the second end of the first transistor;
a second transistor, comprising:
a first end;
a second end;
a first gate end, receiving a second control signal and biasing the second transistor according to the second control signal;
a second gate end, connected to the second end of the second transistor and connected to the second gate end of the first transistor;

a third transistor, comprising:
a first end, receiving a data signal;
a second end, connected to the first end of the second transistor;
a gate end, receiving a third control signal and turning on the third transistor according to the third control signal;

a fourth transistor, comprising:
a first end, connected to the second end of the second transistor;
a second end, connected to a first initial voltage;
a gate end, receiving a fourth control signal and turning on the fourth transistor according to the fourth control signal to reset the second gate end of the first transistor;

a fifth transistor, comprising:
a first end, connected to the second end of the first transistor;
a second end, connected to a second initial voltage;
a gate end, receiving the third control signal or the fourth control signal; and

a light emitting element, comprising:
an anode end, electrically connected to the first end of the fifth transistor, wherein the fifth transistor is turned on according to the third control signal or the fourth control signal to reset the anode end of the light emitting element;
a cathode end, receiving a second supply voltage.

2. An operating method for the pixel driving circuit according to claim 1 , wherein the operating method comprises the following steps:
(A) in a first operating state, resetting the second gate end of the first transistor via the fourth transistor;
(B) in a second operating state, providing the data signal to the second gate end of the second transistor via the second transistor and the third transistor; and
(C) in a third operating state, providing a driving current to the light emitting element via the first transistor.

3. The operating method according to claim 2 , further comprising:
in the first operating state, the fourth control signal is provided to turn on the fourth transistor, and the second gate end of the first transistor receives the first initial voltage; and
in the first operating state, the fourth control signal is provided to turn on the fifth transistor, and the anode end of the light emitting element receives the second initial voltage,
wherein the first transistor and the second transistor are P-type transistors, and the voltage level of the first initial voltage is the same as the voltage level of the second initial voltage; when the first transistor and the second transistor are N-type transistors, the voltage level of the first initial voltage is greater than the voltage level of the second initial voltage.

4. The operating method according to claim 2 , further comprising:
in the first operating state, providing the fourth control signal to turn on the fourth transistor, the second gate end of the first transistor receiving the first initial voltage; and
in the second operating state, providing the third control signal to turn on the fifth transistor, the anode end of the light emitting element receiving the second initial voltage,
wherein when the first transistor and the second transistor are P-type transistors, the voltage level of the first initial voltage is the same as the voltage level of the second initial voltage; when the first transistor and the second transistor are N-type transistors, the voltage level of the first initial voltage is greater than the voltage level of the second initial voltage.

5. The operating method according to claim 2 , wherein the step (B) further comprises:
providing the second control signal to turn on the second transistor; and
providing the third control signal to turn on the third transistor, the second gate end of the first transistor receiving the data signal,
wherein the second control signal is the same as the third control signal, and the voltage level of the first control signal in the third operating state is the same as the voltage level of the second control signal in the second operating state.

6. The operating method according to claim 2 , wherein the step (B) further comprises:
providing the second control signal to bias the second transistor; and
providing the third control signal to turn on the third transistor, the second gate end of the first transistor receiving the data signal,
wherein the second control signal is a reference voltage different from the third control signal, and the voltage level of the first control signal in the third operating state is the same as the voltage level of the reference voltage.

7. The operating method according to claim 2 , wherein the step (B) further comprises:
providing the second control signal to bias the second transistor; and
providing the third control signal to turn on the third transistor, the second gate end of the first transistor receiving the data signal,
wherein the second control signal is the first initial voltage different from the third control signal, and the voltage level of the first control signal in the third operating state is the same as the voltage level of the first initial voltage.

8. The pixel driving circuit according to claim 7 , wherein the first transistor and the second transistor are transistors of the same type, and the third transistor, the fourth transistor and the fifth transistor are transistors of the same type and have different types from the first transistor; in a first operating state, the waveform of first control signal is in the same phase as that of the fourth control signal; and in a second operating state after the first operating state, the waveform of the first control signal is in the same phase as that of the third control signal.

9. The pixel driving circuit according to claim 8 , wherein the second control signal is a reference voltage, and the voltage level of the first control signal in a third operating state after the second operating state is the same as the voltage level of the reference voltage.

10. The pixel driving circuit according to claim 8 , wherein the first gate end of the second transistor is connected to the second end of the fourth transistor, the second control signal is the first initial voltage, and the voltage level of first control signal in a third operating state after the second operating state is the same as the voltage level of the first initial voltage.

11. The pixel driving circuit according to claim 7 , wherein the first transistor, the second transistor, the third transistor, the fourth transistor and the fifth transistor are transistors of the same type; in a first operating state, the waveform of the first control signal is in opposite phase with that of the fourth control signal; and in a second operating state after the first operating state, the waveform of the first control signal is in opposite phase with that of the third control signal.

12. The pixel driving circuit according to claim 11 , wherein the voltage level of the first control signal in a third o

Assignees

• Au Optronics Corp

Inventors

• Cheng Mao-Hsun
• Huang Cheng-Han
• Ma Mei-Sheng
• Chen Yi-Chiung
• Chang Hsiang-Sheng
• Wu Po-Jung
• Chen Yung-Chih
• Cheng Ching-Sheng

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

• G09G2300/08

  Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements · CPC title

• G09G2310/061

  for resetting or blanking · CPC title

• G09G2310/0264

  Details of driving circuits · CPC title