AMOLED pixel driving circuit and method for compensating nonuniform brightness

Patent metadata

Field	Value
Publication number	US-9875688-B2
Application number	US-201514655734-A
Country	US
Kind code	B2
Filing date	Apr 1, 2015
Priority date	Jan 26, 2015
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

The present invention provides an AMOLED pixel driving circuit and a pixel driving method. The AMOLED pixel driving circuit utilizes a 6T2C structure, comprising a first, a second, a third, a fourth, a fifth and a sixth thin film transistors (T 1 , T 2 , T 3 , T 4 , T 5 , T 6 ), a first, a second capacitors (C 1 , C 2 ) and an organic light emitting diode (OLED), and the first thin film transistor (T 1 ) is a drive thin film transistor, and the fifth thin film transistor (T 5 ) is a switch thin film transistor; and a first control signal (G 1 ), a second control signal (G 2 ) and a third control signal (G 3 ) are involved, and the three are combined with one another and correspond to a data signal writing stage ( 1 ), a whole compensation stage ( 2 ), a charging stage ( 3 ) and a light emitting stage ( 4 ) one after another. The threshold voltage changes of the drive thin film transistor and the organic light emitting diode can be effectively compensated to make the display brightness of the AMOLED more even and to raise the display quality.

First claim

What is claimed is:

1. An AMOLED pixel driving circuit, comprising:
a first thin film transistor, a second thin film transistor, a third thin film transistor, a fourth thin film transistor, a fifth thin film transistor, a sixth thin film transistor, a first capacitor, a second capacitor and an organic light emitting diode; the first thin film transistor is a drive thin film transistor, and the fifth thin film transistor is a switch thin film transistor;
a gate of the fifth thin film transistor is electrically coupled to a scan signal, and a source is electrically coupled to a data signal, and a drain is electrically coupled to a first node;
a gate of the fourth thin film transistor is electrically coupled to a first control signal, and a source is electrically coupled to the first node, and a drain is electrically coupled to a second node;
a gate of the third thin film transistor is electrically coupled to a second control signal, and a source is electrically coupled to the second node, and a drain is electrically coupled to a third node;
a gate of the second thin film transistor is electrically coupled to the first control signal, and a source is electrically coupled to the third node, and a drain is electrically coupled to one end of the second capacitor and a reference voltage;
a gate of the first thin film transistor is electrically coupled to the third node, and the drain is electrically coupled to a power source positive voltage, and a source is electrically coupled to a fourth node;
a gate of the sixth thin film transistor is electrically coupled to a third control signal, and a source is electrically coupled to the fourth node, and a drain is electrically coupled to an anode of the organic light emitting diode;
one end of the first capacitor is electrically coupled to the second node, and the other end is electrically coupled to the fourth node;
the one end of the second capacitor is electrically coupled to the drain of the second thin film transistor and the reference voltage, and the other end is electrically coupled to the first node;
the anode of the organic light emitting diode is electrically coupled to the drain of the sixth thin film transistor, and a cathode is electrically coupled to a power source negative voltage.

2. The AMOLED pixel driving circuit according to claim 1 , wherein all of the first thin film transistor, the second thin film transistor, the third thin film transistor, the fourth thin film transistor, the fifth thin film transistor and the sixth thin film transistor are Low Temperature Poly-silicon thin film transistors, oxide semiconductor thin film transistors or amorphous silicon thin film transistors.

3. The AMOLED pixel driving circuit according to claim 1 , wherein all of the first control signal, the second control signal and the third control signal are provided by an external sequence controller.

4. The AMOLED pixel driving circuit according to claim 1 , wherein the first control signal, the second control signal and the third control signal are combined with one another, and correspond to a data signal writing stage, a whole compensation stage, a charging stage and a light emitting stage one after another;
in the data signal writing stage, the first control signal is low voltage level, and the second control signal is high voltage level, and the third control signal is high voltage level;
in the whole compensation stage, the first control signal is low voltage level, and the second control signal is low voltage level, and the third control signal is high voltage level;
in the charging stage, the first control signal is high voltage level, and the second control signal is low voltage level, and the third control signal is high voltage level;
in the light emitting stage, the first control signal is low voltage level, and the second control signal is high voltage level, and the third control signal is high voltage level.

5. The AMOLED pixel driving circuit according to claim 4 , wherein the scan signal is a pulse signal in the data signal writing stage, and is low voltage level in any of the whole compensation stage, the charging stage and the light emitting stage.

6. The AMOLED pixel driving circuit according to claim 1 , wherein the reference voltage is a constant voltage.

7. An AMOLED pixel driving method, comprising steps of:
step S 1 , providing an AMOLED pixel driving circuit;
the AMOLED pixel driving circuit comprises: a first thin film transistor, a second thin film transistor, a third thin film transistor, a fourth thin film transistor, a fifth thin film transistor, a sixth thin film transistor, a first capacitor, a second capacitor and an organic light emitting diode; the first thin film transistor is a drive thin film transistor, and the fifth thin film transistor is a switch thin film transistor;
a gate of the fifth thin film transistor is electrically coupled to a scan signal, and a source is electrically coupled to a data signal, and a drain is electrically coupled to a first node;
a gate of the fourth thin film transistor is electrically coupled to a first control signal, and a source is electrically coupled to the first node, and a drain is electrically coupled to a second node;
a gate of the third thin film transistor is electrically coupled to a second control signal, and a source is electrically coupled to the second node, and a drain is electrically coupled to a third node;
a gate of the second thin film transistor is electrically coupled to the first control signal, and a source is electrically coupled to the third node, and a drain is electrically coupled to one end of the second capacitor and a reference voltage;
a gate of the first thin film transistor is electrically coupled to the third node, and the drain is electrically coupled to a power source positive voltage, and a source is electrically coupled to a fourth node;
a gate of the sixth thin film transistor is electrically coupled to a third control signal, and a source is electrically coupled to the fourth node, and a drain is electrically coupled to an anode of the organic light emitting diode;
one end of the first capacitor is electrically coupled to the second node, and the other end is electrically coupled to the fourth node;
the one end of the second capacitor is electrically coupled to the drain of the second thin film transistor and the reference voltage, and the other end is electrically coupled to the first node;
the anode of the organic light emitting diode is electrically coupled to the drain of the sixth thin film transistor, and a cathode is electrically coupled to a power source negative voltage;
step S 2 , entering a scan stage;
the first control signal provides low voltage level, and both the second, the fourth thin film transistors are deactivated; the second control signal provides high voltage level; the third control signal provides high voltage level; the scan signal is a pulse signal and a line by line scan is implemented, and the data signal is written into the first node line by line and stored in the second capacitor;
step S 3 , entering a whole compensation stage;
all of the scan signals are low voltage level, and the fifth thin film transistors in all pixels are deactivated; the first control signal provides low voltage level, and both the second, the fourth thin film transistors are deactivated; the second control signal provides low voltage level, and the third thin film transistor is deactivated; the third control signal provides high voltage level, and the sixth thin film transistor is activated; the fourth node charges to the organic light emitting diode for a trans-voltage;
step S 4 , entering a charging stage;
all of the scan signals remain to be low voltage level, and the fifth thin film transistor

Assignees

• Shenzhen China Star Optoelect

Inventors

• Han Baixiang

Classifications

• G09G2300/0819

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

• G09G2320/0233

  Improving the luminance or brightness uniformity across the screen · CPC title

• G09G2320/045

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

• G09G3/3233 Primary

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

• G09G2310/0251

  Precharge or discharge of pixel before applying new pixel voltage · CPC title