AMOLED pixel driving circuit and pixel driving method

Patent metadata

Field	Value
Publication number	US-10297199-B2
Application number	US-201615106835-A
Country	US
Kind code	B2
Filing date	May 13, 2016
Priority date	Apr 12, 2016
Publication date	May 21, 2019
Grant date	May 21, 2019

Abstract

Disclosed are an AMOLED pixel driving circuit and a pixel driving method. The AMOLED pixel driving circuit utilizes the 4T2C structure, and comprises: a first thin film transistor (T 1 ), a second thin film transistor (T 2 ), a third thin film transistor (T 3 ), a fourth thin film transistor (T 4 ), a first capacitor (C 1 ), a second capacitor (C 2 ) and an organic light emitting diode (D 1 ); the nth scan signal (SCAN(n)) and the n+1th scan signal (SCAN(n+1)) are combined with each other, and correspond to a threshold voltage sensing stage, a holding stage, a programming stage and a drive stage one after another. In comparison with the pixel driving circuit of the 5T2C structure, the corresponding thin film transistor is controlled merely with arranging the scan signal. There will be the compensation function, and the amount of the control signals can be decreased, and the circuit structure is simplified and the cost is decreased.

First claim

What is claimed is:

1. An active matrix organic light emitting display 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 first capacitor, a second capacitor and an organic light emitting diode, wherein all the respective first thin film transistor, second thin film transistor, third thin film transistor and fourth thin film transistor are P type thin film transistors;
wherein the first thin film transistor is a drive thin film transistor, and a gate of the first thin film transistor is electrically coupled to a first end of the first capacitor through a first node, and a source of the first thin film transistor is electrically coupled to a power source positive voltage, and a drain of the first thin film transistor is electrically coupled to an anode of the organic light emitting diode;
a gate of the second thin film transistor receives a current-row scan signal that corresponds to a current row where the pixel driving circuit is located, and a source of the second thin film transistor receives a data signal, and a drain of the second thin film transistor is electrically coupled to a second end of the first capacitor through a second node;
a gate of the third thin film transistor receives a next-row scan signal that corresponds to a next row that is next to the current row where the pixel driving circuit is, and a source of the third thin film transistor is electrically coupled to the second node, and a drain of the third thin film transistor is electrically coupled to a reference voltage;
a gate of the fourth thin film transistor receives the current-row scan signal, and a source of the fourth thin film transistor is electrically coupled to the first node, and a drain of the fourth thin film transistor is electrically coupled to the anode of the organic light emitting diode;
the first end of the first capacitor is electrically coupled to the first node, and the second end of the first capacitor is electrically coupled to the second node;
a first end of the second capacitor is electrically coupled to the first node, and a second end of the second capacitor is electrically coupled to the power source positive voltage; and
the anode of the organic light emitting diode is electrically coupled to the drain of the first thin film transistor and the drain of the fourth thin film transistor, and a cathode of the organic light emitting diode is electrically coupled to a power source negative voltage; and
wherein the drain of the second thin film transistor and the source of the third thin film transistor are both electrically shorted to the second end of the first capacitor and wherein the second thin film transistor and the third thin film transistor are respectively controlled by the current-row scan signal and the next-row scan signal to supply the data signal and the reference voltage to the second end of the first capacitor at different time periods that are separated by a time interval therebetween.

2. The active matrix organic light emitting display pixel driving circuit according to claim 1 , wherein the reference voltage is a constant voltage.

3. The active matrix organic light emitting display 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 and the fourth thin film transistor are Low Temperature Poly-silicon thin film transistors, oxide semiconductor thin film transistors or amorphous silicon thin film transistors.

4. The active matrix organic light emitting display pixel driving circuit according to claim 1 , wherein the current-row scan signal and the next-row scan signal are each a pulse signal having a falling edge and a rising edge, and the falling edge of the next-row scan signal is later than the rising edge of the current-row scan signal.

5. The active matrix organic light emitting display pixel driving circuit according to claim 4 , wherein the current-row scan signal and the next-row scan signal are combined with each other to provide a threshold voltage sensing stage, a holding stage, a programming stage and a drive stage one after another;
in the threshold voltage sensing stage, the current-row scan signal is a low voltage level, and the next-row scan signal is a high voltage level;
in the holding stage, the current-row scan signal is a high voltage level, and the next-row scan signal is a high voltage level;
in the programming stage, the current-row scan signal is a high voltage level, and the next-row scan signal is a low voltage level;
in the drive stage, the current-row scan signal is a high voltage level, and the next-row scan signal is a high voltage level.

6. An active matrix organic light emitting display pixel driving method, comprising the following steps:
step 1, providing an active matrix organic light emitting display pixel driving circuit;
wherein the active matrix organic light emitting display 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 first capacitor, a second capacitor and an organic light emitting diode, wherein all the respective first thin film transistor, second thin film transistor, third thin film transistor and fourth thin film transistor are P type thin film transistors;
wherein the first thin film transistor is a drive thin film transistor, and a gate of the first thin film transistor is electrically coupled to a first end of the first capacitor through a first node, and a source of the first thin film transistor is electrically coupled to a power source positive voltage, and a drain of the first thin film transistor is electrically coupled to an anode of the organic light emitting diode;
a gate of the second thin film transistor receives a current-row scan signal that corresponds to a current row where the pixel driving circuit is, and a source of the second thin film transistor receives a data signal, and a drain of the second thin film transistor is electrically coupled to a second end of the first capacitor through a second node;
a gate of the third thin film transistor receives a next-row scan signal that corresponds to a next row that is next to the current row where the pixel driving circuit is, and a source of the third thin film transistor is electrically coupled to the second node, and a drain of the third thin film transistor is electrically coupled to a reference voltage;
a gate of the fourth thin film transistor receives the current-row scan signal, and a source of the fourth thin film transistor is electrically coupled to the first node, and a drain of the fourth thin film transistor is electrically coupled to the anode of the organic light emitting diode;
the first end of the first capacitor is electrically coupled to the first node, and the second end of the first capacitor is electrically coupled to the second node;
a first end of the second capacitor is electrically coupled to the first node, and a second end of the second capacitor is electrically coupled to the power source positive voltage; and
the anode of the organic light emitting diode is electrically coupled to the drain of the first thin film transistor and the drain of the fourth thin film transistor, and a cathode of the organic light emitting diode is electrically coupled to a power source negative voltage;
step 2, entering a threshold voltage sensing stage;
wherein the current-row scan signal provides a low voltage level, so that the second thin film transistor and the fourth thin film transistor are activated, and the next-row scan signal provides a high voltage level, so that the third thin film transistor is deactivated; the data signal i

Assignees

• Shenzhen China Star Optoelect

Inventors

• Cai Yuying

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

• G09G2310/0262

  The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes · CPC title

• G09G2300/0852

  being a dynamic memory with more than one capacitor · CPC title

• G09G2310/0208

  using active addressing · CPC title