IP Library › Granted Patent US 8,878,831
Granted Patent B2
US 8,878,831 · App. 13/241,230 · Granted Nov 4, 2014

Pixel driving circuit of an organic light emitting diode

Inventors: Hsuan-Ming Tsai (Hsin-Chu, TW); Chun-Yen Liu (Hsin-Chu, TW)
Assignee: AU Optronics Corp.
G09G3/3233G09G2300/043G09G2300/0819G09G2300/0814G09G2320/045
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Quick Facts
Patent No.
US 8,878,831
App. No.
13/241,230
Granted
Nov 4, 2014
Kind
B2
Abstract

A pixel driving circuit of an organic light emitting diode (OLED) includes a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a capacitor, and an OLED. The operation of the pixel driving circuit includes three stages including discharging, data writing, and emitting. The pixel driving circuit compensates the threshold voltage of the transistor in the stage of data writing, so the driving current of the OLED can be irrelevant to the variations of threshold voltages.

Claims (32)

1. A pixel driving circuit of an organic light emitting diode, comprising:

a first transistor, comprising a first end for receiving a data voltage, a second end, and a control end for receiving a first scan signal;

a capacitor, comprising a first end electrically connected to the second end of the first transistor, and a second end;

a second transistor, comprising a first end electrically connected to a first voltage source, a control end, and a second end electrically connected to the second end of the capacitor;

a third transistor, comprising a first end for receiving a first reference voltage, a second end electrically connected to the control end of the second transistor, and a control end for receiving the first scan signal;

a fourth transistor, comprising a first end electrically connected to the control end of the second transistor, a second end electrically connected to the second end of the first transistor, and a control end for receiving a second scan signal;

a fifth transistor, comprising a first end electrically connected to the second end of the capacitor, a second end, and a control end for receiving a driving signal; and

an organic light emitting diode, comprising a first end electrically connected the second end of the fifth transistor, and a second end electrically connected to a second voltage source, wherein the first scan signal is complementary to the second scan signal.

2. The pixel driving circuit of claim 1 , wherein a voltage level of the first reference voltage equals a voltage level of a voltage provided by the first voltage source.

3. The pixel driving circuit of claim 1 , wherein the first reference voltage is an independent voltage source.

4. The pixel driving circuit of claim 1 , further comprising:

a sixth transistor, comprising a first end electrically connected to the second end of the fifth transistor, a second end for receiving a second reference voltage, and a control end for receiving the first scan signal.

5. The pixel driving circuit of claim 1 , wherein the first transistor, the second transistor, the third transistor, the fourth transistor and the fifth transistor are N-type transistors.

6. The pixel driving circuit of claim 1 , wherein when the first transistor, the third transistor and the fifth transistor are turned on and the fourth transistor is turned off, the capacitor discharges via the fifth transistor for resetting a voltage of the second end of the second transistor.

7. The pixel driving circuit of claim 1 , wherein when the first transistor and the third transistor are turned on and the fourth transistor and the fifth transistor are turned off, a voltage of the second end of the second transistor is generated according to the first reference voltage and a threshold voltage of the second transistor.

8. The pixel driving circuit of claim 1 , wherein when the fourth transistor and the fifth transistor are turned on and the first transistor and the third transistor are turned off, the organic light emitting diode is driven to emit light according to a current generated by the data voltage and the first reference voltage.

9. A pixel driving circuit of an organic light emitting diode, comprising:

a first transistor, comprising a first end for receiving a data voltage, a second end, and a control end for receiving a first scan signal;

a capacitor, comprising a first end electrically connected to the second end of the first transistor, and a second end;

a second transistor, comprising a first end electrically connected to a first voltage source, a control end, and a second end electrically connected to the second end of the capacitor;

a third transistor, comprising a first end for receiving a first reference voltage, a second end electrically connected to the control end of the second transistor, and a control end for receiving the first scan signal;

a fourth transistor, comprising a first end electrically connected to the control end of the second transistor, a second end electrically connected to the second end of the first transistor, and a control end for receiving a second scan signal;

a fifth transistor, comprising a first end electrically connected to the second end of the capacitor, a second end, and a control end for receiving a driving signal; and

an organic light emitting diode, comprising a first end electrically connected the second end of the fifth transistor, and a second end electrically connected to a second voltage source, wherein when the first transistor and the third transistor are turned on and the fourth transistor and the fifth transistor are turned off, a voltage of the second end of the second transistor is generated according to the first reference voltage and a threshold voltage of the second transistor.

10. A pixel driving circuit of an organic light emitting diode, comprising:

a first transistor, comprising a first end for receiving a data voltage, a second end, and a control end for receiving a first scan signal;

a capacitor, comprising a first end electrically connected to the second end of the first transistor, and a second end;

a second transistor, comprising a first end electrically connected to a first voltage source, a control end, and a second end electrically connected to the second end of the capacitor;

a third transistor, comprising a first end for receiving a first reference voltage, a second end electrically connected to the control end of the second transistor, and a control end for receiving the first scan signal;

a fourth transistor, comprising a first end electrically connected to the control end of the second transistor, a second end electrically connected to the second end of the first transistor, and a control end for receiving a second scan signal;

a fifth transistor, comprising a first end electrically connected to the second end of the capacitor, a second end, and a control end for receiving a driving signal; and

an organic light emitting diode, comprising a first end electrically connected the second end of the fifth transistor, and a second end electrically connected to a second voltage source, wherein when the fourth transistor and the fifth transistor are turned on and the first transistor and the third transistor are turned off, the organic light emitting diode is driven to emit light according to a current generated by the data voltage and the first reference voltage.

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Sep 23, 2011
From: TSAI, HSUAN-MING; LIU, CHUN-YEN
To: AU OPTRONICS CORP.
Reel/Frame 026952/0685 →
Priority Claims (1)
TW 99138807 A · Nov 11, 2010 · national
Continuity (1)
Related Publication 20120120042A1 · May 17, 2012