PIXEL AND ORGANIC LIGHT EMITTING DISPLAY DEVICE USING THE SAME

• US 20100013816A1
• Filed: 07/10/2009
• Published: 01/21/2010
• Est. Priority Date: 07/18/2008
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Kwak, Won-Kyu
• Granted Patent: US 8,237,634 B2
• Time in Patent Office: Days
• US Class Current: 345/211
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2300/0861 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 Class Codes: G09G 2310/0248 Precharge or discharge of column electrodes before or after applying exact column voltages
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

A pixel capable of improving response characteristics and displaying an image having a uniform image quality, and an organic light emitting display device using the same. The pixel includes an organic light emitting diode coupled between first power and second power; a pixel circuit coupled between the first power and the organic light emitting diode for supplying a driving current to the organic light emitting diode; and a first transistor for supplying a reset voltage to an anode electrode of the organic light emitting diode during a first period when a previous scan signal is supplied to a previous scan line.

Claims

1. A pixel of an organic light emitting display device comprising:

an organic light emitting diode coupled between a first power and a second power;

a pixel circuit coupled between the first power and the organic light emitting diode for supplying a driving current to the organic light emitting diode; and

a first transistor for supplying a reset voltage to an anode electrode of the organic light emitting diode during a first period when a previous scan signal is supplied to a previous scan line coupled to the first transistor.

2. The pixel as claimed in claim 1, wherein:

the reset voltage is a voltage of separate initialization power; and

the first transistor is coupled between the anode electrode of the organic light emitting diode and the initialization power, and a gate electrode of the first transistor is coupled to the previous scan line.

3. The pixel as claimed in claim 1, wherein:

the reset voltage is a voltage of the second power; and

the first transistor is coupled between the anode electrode of the organic light emitting diode and the second power, and a gate electrode of the first transistor is coupled to the previous scan line.

4. The pixel as claimed in claim 1, wherein the pixel circuit comprises:

a second transistor coupled between a data line and a first node and having a gate electrode coupled to a current scan line;

a third transistor coupled between the first node and the organic light emitting diode and having a gate electrode coupled to a second node; and

a first capacitor coupled between the second node and the first power.

5. The pixel as claimed in claim 4, wherein the pixel circuit further comprises:

a fourth transistor coupled between the gate electrode of the third transistor and a drain electrode of the third transistor, and having a gate electrode coupled to the current scan line;

a fifth transistor coupled between the first power and the first node, and having a gate electrode coupled to a light-emitting control line;

a sixth transistor coupled between the third transistor and the organic light emitting diode, and having a gate electrode coupled to the light-emitting control line; and

a seventh transistor coupled between the second node and the initialization power, and having a gate electrode coupled to the previous scan line.

6. The pixel as claimed in claim 4, wherein the pixel circuit further comprises a second capacitor coupled between the second node and the current scan line.

7. An organic light emitting display device comprising a plurality of pixels at crossing regions of scan lines, light-emitting control lines, and data lines,

each of the pixels comprising:

an organic light emitting diode coupled between a first power and a second power;

a pixel circuit coupled between the first power and the organic light emitting diode for supplying a driving current to the organic light emitting diode; and

a first transistor for supplying a reset voltage to an anode electrode of the organic light emitting diode during a first period when a previous scan signal is supplied to a previous scan line of the scan lines.

8. The organic light emitting display device as claimed in claim 7, wherein:

the reset voltage is a voltage of separate initialization power; and

the first transistor is coupled between the anode electrode of the organic light emitting diode and the initialization power, and a gate electrode of the first transistor is coupled to the previous scan line.

9. The organic light emitting display device as claimed in claim 7, wherein:

the reset voltage is a voltage of the second power; and

the first transistor is coupled between the anode electrode of the organic light emitting diode and the second power, and a gate electrode of the first transistor is coupled to the previous scan line.

10. A method of driving a pixel of an organic light emitting display, the pixel comprising an organic light emitting diode coupled to a driving transistor, the pixel coupled to a scan line, a previous scan line, a light-emitting control line, and a data line, the method comprising:

after a previous frame and prior to applying a scan signal to the scan line in a current frame, setting a voltage at an anode of the organic light emitting diode to a reset voltage;

applying the scan signal to the scan line;

applying a data signal to the data line; and

applying a light-emitting signal to the light-emitting control line to enable the organic light emitting diode to emit light,

wherein the reset voltage remains substantially constant in the previous frame and the current frame.

11. The method as claimed in claim 10, wherein said setting the voltage at the anode of the organic light emitting diode to a reset voltage comprises:

applying a previous scan signal to the previous scan line in the previous frame; and

setting the voltage at the anode of the organic light emitting diode to the reset voltage in response to the previous scan signal.

12. The method as claimed in claim 11, wherein a voltage at a gate of the driving transistor corresponds to the voltage at the anode of the organic light emitting diode in response to the previous scan signal.