PIXEL CIRCUIT AND ORGANIC LIGHT EMITTING DISPLAY APPARATUS INCLUDING THE SAME

• US 20110063197A1
• Filed: 03/02/2010
• Published: 03/17/2011
• Est. Priority Date: 09/14/2009
• Status: Abandoned Application

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Kim, Keum-Nam, Chung, Bo-Yong
• Application Number:
  US12/716,134
• Publication Number:
  US 20110063197A1
• Time in Patent Office: Days
• US Class Current: 345/82
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

A pixel circuit includes: a second NMOS transistor coupled to a data line and a scan line, the second NMOS transistor for supplying data signals to a first node; a capacitor having a first terminal coupled to the first node and a second terminal coupled to a second node; an OLED having a first terminal coupled to the second node and a second terminal coupled to a second power source; a first NMOS transistor including a first electrode, a second electrode, and a gate electrode coupled to the first node, and for supplying a current corresponding to a voltage applied to the first node from a first power source to the second power source via the OLED; and a third NMOS transistor coupled to the first NMOS transistor in series and configured to be turned on when a light emission control signal is supplied from a light emission control line.

Claims

1. A pixel circuit of an organic light emitting display, the pixel circuit comprising:

a second N-channel metal oxide semiconductor (NMOS) transistor coupled to a data line and a scan line, the second NMOS transistor being for supplying data signals to a first node;

a storage capacitor having a first terminal coupled to the first node and a second terminal coupled to a second node;

an organic light emitting diode (OLED) having a first terminal coupled to the second node and a second terminal coupled to a second power source;

a first NMOS transistor comprising a first electrode, a second electrode, and a gate electrode coupled to the first node, and for supplying a current corresponding to a voltage applied to the first node from a first power source to the second power source via the OLED; and

a third NMOS transistor coupled to the first NMOS transistor in series and configured to be turned on when a light emission control signal is supplied from a light emission control line.

2. The pixel circuit of claim 1, wherein the first electrode of the first NMOS transistor is a drain electrode and the second electrode of the first NMOS transistor is a source electrode, and the second electrode of the first NMOS transistor is coupled to the second node.

3. The pixel circuit of claim 1, wherein the third NMOS transistor comprises:

a gate electrode coupled to the light emission control line;

a first electrode coupled to the first power source; and

a second electrode coupled to the first electrode of the first NMOS transistor.

4. The pixel circuit of claim 1, wherein the third NMOS transistor comprises:

a gate electrode coupled to the light emission control line;

a first electrode coupled to the second electrode of the first NMOS transistor; and

a second electrode coupled to the second node.

5. The pixel circuit of claim 1, wherein the second NMOS transistor is configured to be turned on when a scan signal is supplied from the scan line.

6. The pixel circuit of claim 1, further comprising a third power source for applying a reference voltage to the second node.

7. The pixel circuit of claim 1, wherein the first power source is configured to supply a first voltage, and the second power source is configured to supply a second voltage that is lower than the first voltage.

8. An organic light emitting display apparatus comprising:

a first scan driver coupled to light emission control lines for supplying light emission control signals;

a second scan driver coupled to scan lines for supplying scan signals;

a data driver coupled to data lines for supplying data signals; and

a display unit comprising a plurality of pixel circuits coupled to the scan lines, the light emission control lines, and the data lines,

wherein each of the pixel circuits comprises;

a second N-channel metal oxide semiconductor (NMOS) transistor for supplying a corresponding one of the data signals to a first node, the second NMOS transistor coupled to a corresponding one of the data lines and a corresponding one of the scan lines;

a storage capacitor having a first terminal coupled to the first node and a second terminal coupled to a second node;

an organic light emitting diode (OLED) having a first terminal coupled to the second node and a second terminal coupled to a second power source;

a first NMOS transistor comprising a first electrode, a second electrode, and a gate electrode coupled to the first node, and for supplying a current corresponding to a voltage applied to the first node from a first power source to the second power source via the OLED; and

a third NMOS transistor coupled to the first NMOS transistor in series and configured to be turned on when a corresponding one of the light emission control signals is supplied from a corresponding one of the light emission control lines.

9. The organic light emitting display apparatus of claim 8, wherein the first electrode of the first NMOS transistor is a drain electrode and the second electrode of the first NMOS transistor is a source electrode, and the second electrode of the first NMOS transistor is coupled to the second node.

10. The organic light emitting display apparatus of claim 8, wherein the third NMOS transistor comprises:

a gate electrode coupled to the corresponding light emission control line;

a first electrode coupled to the first power source; and

a second electrode coupled to the first electrode of the first NMOS transistor.

11. The organic light emitting display apparatus of claim 8, wherein the third NMOS transistor comprises:

a gate electrode coupled to the corresponding one of the light emission control lines;

a first electrode coupled to the second electrode of the first NMOS transistor; and

a second electrode coupled to the second node.

12. The organic light emitting display apparatus of claim 8, wherein the second NMOS transistor is configured to be turned on when a corresponding one of the scan signals is supplied from a corresponding one of the scan lines.

13. The organic light emitting display apparatus of claim 8, further comprising a third power source for applying a reference voltage to the second node.

14. The organic light emitting display apparatus of claim 8, wherein the first power source is configured to apply a first voltage, and the second power source is configured to apply a second voltage that is lower than the first voltage.