Pixel and organic light emitting display device using the same

Patent metadata

Field	Value
Publication number	US-9549450-B2
Application number	US-201213666230-A
Country	US
Kind code	B2
Filing date	Nov 1, 2012
Priority date	Jul 25, 2012
Publication date	Jan 17, 2017
Grant date	Jan 17, 2017

Abstract

A pixel includes an organic light emitting diode, a first transistor that controls an amount of current supplied to the organic light emitting diode, a second transistor connected between a gate electrode of the first transistor and an initialization power supply, and a third transistor diode-connected between an anode electrode of the organic light emitting diode and the initialization power supply.

First claim

What is claimed is:

1. A pixel, comprising:
an organic light emitting diode;
a first transistor that controls an amount of current supplied to the organic light emitting diode;
a second transistor connected between a gate electrode of the first transistor and an initialization power supply; and
a third transistor being directly connected between an anode electrode of the organic light emitting diode and the initialization power supply and including a first electrode and a second electrode, wherein:
the first electrode of the third transistor is electrically connected to the anode electrode of the organic light emitting diode, and
the second electrode of the third transistor is electrically connected to the initialization power supply, and wherein
when the third transistor is reverse-diode-connected, a leakage current flows from the anode electrode of the organic light emitting diode to the initialization power supply through the third transistor being reverse-diode-connected.

2. The pixel according to claim 1 , wherein the gate electrode of the third transistor is connected to the gate electrode of the first transistor.

3. The pixel according to claim 1 , wherein the initialization power supply is set to a voltage lower than a voltage applied to the anode electrode of the organic light emitting diode.

4. The pixel according to claim 1 , wherein a voltage applied to the gate electrode of the first transistor is set to a voltage higher than a voltage applied to the anode electrode of the organic light emitting diode.

5. The pixel according to claim 1 , further comprising:
a fourth transistor connected between the gate electrode of the first transistor and a second electrode of the first transistor, the fourth transistor being turned on after the second transistor is turned on;
a fifth transistor connected between a first electrode of the first transistor and a data line, the fifth transistor being turned on and turned off simultaneously with the fourth transistor;
a sixth transistor connected between the first electrode of the first transistor and a first power supply, the sixth transistor being turned off during a period of time when the second and fourth transistors are turned on and being turned on during another period of time; and
a seventh transistor connected to the second electrode of the first transistor and the organic light emitting diode, the seventh transistor being turned on and turned off simultaneously with the sixth transistor.

6. The pixel according to claim 5 , further comprising a storage capacitor connected between the gate electrode of the first transistor and the first power supply.

7. The pixel according to claim 1 , wherein a gate electrode of the third transistor is electrically and directly connected to the anode electrode of the organic light emitting diode.

8. An organic light emitting display device, comprising:
a scan driving unit that supplies scan signals to scan lines and that supplies light emitting control signals to light emitting control lines;
a data driving unit that supplies a data signal to data lines; and
pixels positioned at intersections of the scan lines and the data lines, each of the pixels including:
an organic light emitting diode;
a first transistor that controls an amount of current supplied to the organic light emitting diode;
a second transistor connected between a gate electrode of the first transistor and an initialization power supply, the second transistor being turned on when one of the scan signals is supplied to a previous scan line; and

a third transistor being directly connected between an anode electrode of the organic light emitting diode and the initialization power supply and including a first electrode and a second electrode, wherein:
the first electrode of the third transistor is electrically connected to the anode electrode of the organic light emitting diode, and
the second electrode of the third transistor is electrically connected to the initialization power supply, and wherein
when the third transistor is reverse-diode-connected, a leakage current flows from the anode electrode of the organic light emitting diode to the initialization power supply through the third transistor being reverse-diode-connected.

9. The organic light emitting display device according to claim 8 , wherein the gate electrode of the third transistor is connected to the gate electrode of the first transistor.

10. The organic light emitting display device according to claim 8 , wherein the initialization power supply is set to a voltage lower than a voltage applied to the anode electrode of the organic light emitting diode.

11. The organic light emitting display device according to claim 8 , wherein the data signal is set to a voltage lower than a voltage applied to the anode electrode of the organic light emitting diode.

12. The organic light emitting display device according to claim 8 , further comprising:
a fourth transistor connected between the gate electrode of the first transistor and a second electrode of the first transistor, the fourth transistor being turned on when another of the scan signals is supplied to a current scan line;
a fifth transistor connected between the a first electrode of the first transistor and one of the data lines, the fifth transistor being turned on when the other of the scan signals is supplied to the current scan line;
a sixth transistor connected between the first electrode of the first transistor and a first power supply, the sixth transistor being turned off during a period of time when a light emitting control signal is supplied to a current light emitting control line and being turned on in another period; and
a seventh transistor connected to the second electrode of the first transistor and the organic light emitting diode, the seventh transistor being turned off when the light emitting control signal is supplied to the current light emitting control line and being turned on in the other period.

13. The organic light emitting display device according to claim 12 , wherein the previous scan line is an i−1-th scan line, the current scan line is an i-th scan line, and the current light emitting control line is an i-th light emitting control line.

14. The organic light emitting display device according to claim 13 , wherein the scan driving unit supplies the light emitting control signal to the current light emitting control line so as to overlap the light emitting control signal with scan signals supplied to the previous scan line and the current scan line.

15. The organic light emitting display device according to claim 12 , further comprising a storage capacitor connected between the gate electrode of the first transistor and the first power supply.

Assignees

• Kim Dong-Hwi
• Samsung Display Co Ltd

Inventors

• Kim Dong-Hwi

Classifications

• H05B45/60 Primary

  Circuit arrangements for operating LEDs comprising organic material, e.g. for operating organic light-emitting diodes [OLED] or polymer light-emitting diodes [PLED] · CPC title

• G09G3/3241 Primary

  the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror · CPC title

• G09G2300/0819

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

• G09G2300/0842

  forming a memory circuit, e.g. a dynamic memory with one capacitor · CPC title

• G09G3/3233

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