Organic light emitting display device and driving method thereof

Patent metadata

Field	Value
Publication number	US-9898963-B2
Application number	US-201514945216-A
Country	US
Kind code	B2
Filing date	Nov 18, 2015
Priority date	May 13, 2013
Publication date	Feb 20, 2018
Grant date	Feb 20, 2018

Abstract

An organic light emitting display device is disclosed. One inventive aspect includes a plurality of pixels provided at a region sectioned by scan lines and data lines and an initialization power unit. The plurality of pixels are configured to control the amount of a current flowing from a first power source to a second power source through an organic light emitting diode in response to a data signal. The initialization power unit supplies initialization power to a driving transistor within each pixel circuit. The initialization power unit further controls the voltage of the initialization power supply to maintain a substantially constant voltage difference between the second power source and the initialization power.

First claim

What is claimed is:

1. An organic light emitting display device, comprising:
a plurality of pixels formed in a region defined by intersections of a plurality of scan lines and a plurality of data lines, the pixels being configured to control an amount of current flowing from a first power source to a second power source through an organic light emitting diode in response to at least a data signal; and
an initialization power generator configured to supply an initialization power to a driving transistor of one of the plurality of pixels, wherein the initialization power generator is configured to control a voltage of the initialization power to maintain a constant voltage difference between the second power source and the initialization power, and wherein a voltage of the second power source and the voltage of the initialization power are different,
wherein one of the plurality of the pixels further comprises a first transistor electrically connected between the organic light emitting diode and the initialization power voltage, the first transistor being configured such that leakage current flowing therethrough is independent of changes in the load to the pixels.

2. The organic light emitting display device of claim 1 , wherein the initialization power is set to have a voltage lower than the second power source.

3. The organic light emitting display device of claim 1 , wherein the initialization power generator further comprises:
a voltage meter configured to measure a voltage of the second power source; and
a voltage generator configured to generate the initialization power to maintain the constant voltage difference between the second power source and the initialization power based on the measured voltage.

4. The organic light emitting display device of claim 1 , wherein the initialization power generator comprises:
a comparator configured to compare a voltage difference between an external initialization power supplied from an external device and the second power source; and
a generator configured to generate the initialization power by controlling a voltage of the external initialization power to maintain the constant voltage difference between the second power source and the initialization power in response to a comparison result generated by the comparator.

5. The organic light emitting display device of claim 4 , wherein the initialization power generator outputs at least any one of the external initialization power and the initialization power in response to a control signal supplied from the external device.

6. The organic light emitting display device of claim 1 , wherein each of the pixels comprises:
a pixel circuit comprising the driving transistor,
wherein the first transistor is electrically connected between an anode electrode of the organic light emitting diode and the initialization power.

7. The organic light emitting display device of claim 6 , wherein the first transistor is connected to any one of the scan lines.

8. The organic light emitting display device of claim 6 , wherein each of the pixels is connected to at least one scan line, light emitting control line and data line.

9. The organic light emitting display device of claim 8 , wherein each of the pixels on a jth horizontal line (where j is a natural number) comprises:
the driving transistor configured to control an amount of a current from the first power source to the organic light emitting diode connected through a first node in response to a voltage of a second node;
a fifth transistor between a data line and the first node and turned on when a scan signal is supplied to a jth scan line;
a third transistor connected between the second node and the initialization power and turned on when the scan signal is supplied to a j−1th scan line; and
a fourth transistor connected between the second node and a second electrode of the driving transistor and turned on when the scan signal is supplied to the jth scan line.

10. The organic light emitting display device of claim 9 , wherein the first transistor of each of the pixels on the jth horizontal line is connected to a j+1 th scan line.

11. The organic light emitting display device of claim 9 , wherein each of the pixels on a jth horizontal line (where j is a natural number) further comprises:
a sixth transistor connected between the first node and the first power source, the sixth transistor turned off when a light emitting control signal is supplied to a jth light emitting control line, and the sixth transistor turned on when the light emitting control signal is not supplied to the jth light emitting control line; and
a seventh transistor connected between a second electrode of the first transistor and the anode electrode of the organic light emitting diode, turned off when the light emitting control signal is supplied to the jth light emitting control line and turned on in all other situations.

12. A method of driving an organic light emitting display device comprising a pixel configured to control an amount of a current flowing from a first power source to a second power source through an organic light emitting diode, the method comprising:
generating an initialization power to maintain a constant voltage difference between the second power source and the initialization power, wherein the pixel comprises a first transistor electrically connected between the organic light emitting diode and the initialization power voltage, and wherein a voltage of the second power source and the voltage of the initialization power are different;
supplying a voltage of the initialization power to a driving transistor of the pixel before a data signal is supplied; and
supplying a leakage voltage through the first transistor, wherein the leakage current is independent of changes in the load to the pixel.

13. The method of claim 12 , wherein generating the initialization power comprises generating the initialization power having a voltage lower than the second power source.

14. The method of claim 12 , wherein generating the initialization power comprises:
measuring a voltage of the second power source; and
generating the initialization power to have the voltage difference between the second power source and the initialization power based on the measured voltage.

15. The method of claim 12 , wherein generating the initialization power comprises:
comparing a voltage difference between an external initialization power and the second power source from an external device to generate a comparison result; and
generating the initialization power by controlling a voltage of the external initialization power to maintain the constant voltage difference between the second power source and the initialization power in response to the comparison result.

16. The method of claim 15 , wherein generating the initialization power comprising outputting at least any one of the external initialization power and the initialization power in response to a control signal sent from the external device.

17. The method of claim 12 further comprising:
controlling an amount of a current to the organic light emitting diode connected through a first node in response to a voltage of a second node;
turning on a fifth transistor between a data line and the first node when a scan signal is supplied to a jth scan line;
turning on a third transistor connected to the second node and the initialization power when the scan signal is supplied to a j−1th scan line; and
turning on a fourth transistor connected between the second node and a second electrode of the driving transistor whe

Assignees

• Samsung Display Co Ltd

Inventors

• Lee Sang Hyun
• Kim Jong Woon

Classifications

• G09G2300/0819

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

• G09G3/3291

  in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements · CPC title

• G09G2310/0243

  Details of the generation of driving signals · CPC title

• G09G2300/0426

  Layout of electrodes and connections · CPC title