OLED current drive pixel circuit

• US 6,734,636 B2
• Filed: 06/21/2002
• Issued: 05/11/2004
• Est. Priority Date: 06/22/2001
• Status: Active Grant

• Current Assignee: InnoLux Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Sanford, James Lawrence, Libsch, Frank Robert
• Primary Examiner(s): Philogene, Haissa
• Application Number:
  US10/176,931
• Publication Number:
  US 20020195968A1
• Time in Patent Office: 690 Days
• Field of Search: 315/169.1, 315/169.3, 345/46, 345/76, 345/77, 345/80, 345/82, 345/204, 257/59, 257/88
• US Class Current: 315/169.3
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/325 the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver

Abstract

There is provided a method for driving an organic light emitting diode (OLED) pixel circuit. The method includes applying a first signal to a terminal of the OLED when setting a state of the pixel circuit, and applying a second signal to the terminal when viewing the state. There is also provided a driver for an OLED pixel circuit, where the driver employs this method.

Claims

1. A method for driving an organic light emitting diode (OLED) pixel circuit comprising:

applying a first signal to a terminal of said OLED when setting a state of said pixel circuit; and

applying a second signal to said terminal when viewing said state.

2. The method of claim 1, wherein said first signal causes said OLED to be off.

3. The method of claim 1, wherein said first signal causes said OLED to be reverse biased.

4. The method of claim 1, wherein said second signal allows said OLED to be forward biased.

5. The method of claim 1, wherein said state is set by a current drive.

6. The method of claim 1, further comprising altering a duty factor of said first signal with respect to said second signal.

7. The method of claim 1, wherein said pixel circuit is one of a plurality of pixel circuits, and wherein said method further comprises applying said first signal and said second signal to a terminal of each of said plurality of pixel circuits.

8. A driver for an organic light emitting diode (OLED) pixel circuit comprising:

a switch,

wherein said switch directs a first signal to a terminal of said OLED when setting a state of said pixel circuit; and

wherein said switch directs a second signal to said terminal when viewing said state.

9. The driver of claim 8, wherein said first signal causes said OLED to be off.

10. The driver of claim 8, wherein said first signal causes said OLED to be reverse biased.

11. The driver of claim 8, wherein said second signal allows said OLED to be forward biased.

12. The driver of claim 8, wherein said state is set by a current drive.

13. The driver of claim 8, wherein said switch is controlled to alter a duty factor of said first signal with respect to said second signal.

14. The driver of claim 8, wherein said pixel circuit is configured of a material selected from the group consisting of amorphous silicon, polysilicon and crystalline silicon.

15. The driver of claim 8, wherein said pixel circuit provides current through said OLED through a single transistor.

16. The driver of claim 15, wherein said transistor operates in saturation when said switch directs said second signal to said terminal.

17. The driver of claim 8,

wherein said pixel circuit is one of a plurality of pixel circuits, and

wherein said switch directs said first signal and said second signal to a terminal of each of said plurality of pixel circuits.