Pixel circuit for organic light emitting display and driving method thereof, organic light emitting display

Patent metadata

Field	Value
Publication number	US-9646536-B2
Application number	US-201615250774-A
Country	US
Kind code	B2
Filing date	Aug 29, 2016
Priority date	Dec 26, 2012
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

A pixel circuit for an organic light emitting display includes first, second, third, fourth, fifth, and sixth MOS transistors, a first capacitor, and an organic light emitting diode. The gate electrode of the first MOS transistor receives a first scanning signal. The first electrode of the first MOS transistor receives a data signal. The gate electrode of the third MOS transistor receives a control signal. The gate electrode of the fourth MOS transistor receives the first scanning signal. The gate electrode of the fifth MOS transistor receives the control signal. The first electrode of the fifth MOS transistor receives a reference voltage. The gate electrode of the sixth MOS transistor receives a second scanning signal. The first electrode of the sixth MOS transistor receives the reference voltage.

First claim

What is claimed is:

1. A driving method for a pixel circuit, the pixel circuit comprising: an organic light emitting diode; a first MOS transistor, comprising a gate electrode, a first electrode, and a second electrode; a second MOS transistor, comprising a gate electrode, a first electrode, and a second electrode, wherein the first electrode of the second MOS transistor is coupled to a first power supply; a third MOS transistor, comprising a gate electrode, a first electrode, and a second electrode, wherein the first electrode of the third MOS transistor is coupled to the second electrode of the second MOS transistor, and the second electrode of the third MOS transistor is coupled to a second power supply via the organic light emitting diode; a fourth MOS transistor, comprising a gate electrode, a first electrode, and a second electrode, wherein the first electrode of the fourth MOS transistor is coupled to the gate electrode of the second MOS transistor, and the second electrode of the fourth MOS transistor is coupled to the second electrode of the second MOS transistor; a fifth MOS transistor, comprising a gate electrode, a first electrode, and a second electrode; a sixth MOS transistor, comprising a gate electrode, a first electrode, and a second electrode; and a first capacitor, comprising first and second terminals, wherein the first terminal of the first capacitor is coupled to the second electrode of the first MOS transistor and is coupled to the second electrode of the fifth MOS transistor, and the second terminal is coupled to the gate electrode of the second MOS transistor and is diode coupled to the first electrode of the fourth MOS transistor, wherein the gate electrode of the first MOS transistor receives a first scanning signal, the first electrode of the first MOS transistor receives a data signal, the gate electrode of the third MOS transistor receives a control signal, the gate electrode of the fourth MOS transistor receives the first scanning signal, the gate electrode of the fifth MOS transistor receives the control signal, the first electrode of the fifth MOS transistor receives a reference voltage, the gate electrode of the sixth MOS transistor receives a second scanning signal, and the first electrode of the sixth MOS transistor receives the reference voltage, the method comprises:
during an initialization stage, turning off the first MOS transistor and the fourth MOS transistor via the first scanning signal, turning off the third MOS transistor and the fifth MOS transistor via the control signal received by the gate electrode of the third MOS transistor, and turning on the sixth MOS transistor via the second scanning signal.

2. The driving method according to claim 1 , further comprising, turning on the first MOS transistor and the fourth MOS transistor via the first scanning signal during a data-writing stage, wherein the data signal received by the first electrode of the first MOS transistor is transmitted to the first terminal of the first capacitor through the first MOS transistor; turning off the sixth MOS transistor via the second scanning signal received by the gate electrode of the sixth MOS transistor; and turning off the third MOS transistor and the fifth MOS transistor via the control signal received by the gate electrode of the third MOS transistor.

3. The driving method according to claim 2 , further comprising during a light emitting stage, turning off the first MOS transistor and the fourth MOS transistor via the first scanning signal turning off the sixth MOS transistor via the second scanning signal received by the gate electrode of the sixth MOS transistor; turning on the fifth MOS transistor and the third MOS transistor via the control signal, wherein a voltage at the gate electrode of the second MOS transistor is based on the data signal received by the first electrode of the first MOS transistor, a drive current is generated by the third MOS transistor based on the data signal, and the drive current is configured to cause the organic light emitting diode to emit light according to the data signal.

4. The driving method according to claim 1 , wherein the data signal is provided during the data-writing stage and the data signal is not provided during the initialization stage and during the light emitting stage.

5. The driving method according to claim 1 , wherein the first scanning signal and the second scanning signal do not overlap.

6. An organic light emitting display comprising:
a scanning drive unit;
a data drive unit;
N scan lines;
M data lines; and
a plurality of pixel circuits, each of the pixel circuits comprising:
an organic light emitting diode;
a first MOS transistor, comprising a gate electrode, a first electrode, and a second electrode;
a second MOS transistor, comprising a gate electrode, a first electrode, and a second electrode, wherein the first electrode of the second MOS transistor is coupled to a first power supply;
a third MOS transistor, comprising a gate electrode, a first electrode, and a second electrode, wherein the first electrode of the third MOS transistor is coupled to the second electrode of the second MOS transistor, and the second electrode of the third MOS transistor is coupled to a second power supply via the organic light emitting diode;
a fourth MOS transistor, comprising a gate electrode, a first electrode, and a second electrode, wherein the first electrode of the fourth MOS transistor is coupled to the gate electrode of the second MOS transistor, and the second electrode of the fourth MOS transistor is coupled to the second electrode of the second MOS transistor;
a fifth MOS transistor, comprising a gate electrode, a first electrode, and a second electrode;
a sixth MOS transistor, comprising a gate electrode, a first electrode, and a second electrode; and
a first capacitor, comprising first and second terminals, wherein the first terminal of the first capacitor is coupled to the second electrode of the first MOS transistor and is coupled to the second electrode of the fifth MOS transistor, and the second terminal is coupled to the gate electrode of the second MOS transistor and is coupled to the first electrode of the fourth MOS transistor,
wherein the gate electrode of the first MOS transistor receives a first scanning signal, the first electrode of the first MOS transistor receives a data signal, the gate electrode of the third MOS transistor receives a control signal, the gate electrode of the fourth MOS transistor receives the first scanning signal, the gate electrode of the fifth MOS transistor receives the control signal, the first electrode of the fifth MOS transistor receives a reference voltage, the gate electrode of the sixth MOS transistor receives a second scanning signal, and the first electrode of the sixth MOS transistor receives the reference voltage,

wherein the scanning drive unit is configured to provide scanning signals to respective scan lines, the data drive unit is configured to provide data signals to respective data lines, and the plurality of the pixel circuits are respectively arranged in pixel areas formed near intersections of the scan lines and the data lines, and
wherein the gate electrodes of the first MOS transistor and the fourth MOS transistor are both coupled to an nth scan line, and the gate electrode of the sixth MOS transistor is coupled to an (n+1)th scan line, where 1≦n<N.

7. The organic light emitting display according to claim 6 , wherein the first scanning signal and the second scanning signal do not overlap.

8. The organic light emitting display according to claim 6 , wherein the first MOS transistor, the second MOS transistor, the third MOS transistor, the fourth MOS transistor, the fifth MOS transistor and the sixth MOS transi

Assignees

• Shanghai Tianma Microelectronics Co Ltd

Inventors

• Qian Dong
• Liu Gang
• Liu Chen

Classifications

• G09G3/3258 Primary

  with pixel circuitry controlling the voltage across the light-emitting element · CPC title

• G09G2300/0439

  Pixel structures · CPC title

• G09G3/3275

  Details of drivers for data electrodes · CPC title

• G09G3/3233 Primary

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

• G09G2320/0233

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