Data voltage current drive amoled pixel circuit

• US 7,071,932 B2
• Filed: 11/05/2002
• Issued: 07/04/2006
• Est. Priority Date: 11/20/2001
• Status: Expired due to Fees

• Current Assignee: InnoLux Corporation
• Original Assignee: Toppoly Optoelectronics Corporation (InnoLux Corporation)
• Inventors: Sanford, James L, Libsch, Frank R
• Primary Examiner(s): Awad, Amr A.
• Assistant Examiner(s): SHENG, TOM V
• Application Number:
  US10/287,937
• Publication Number:
  US 20030095087A1
• Time in Patent Office: 1,337 Days
• Field of Search: 345/82, 345/84, 345/204, 345211-213, 315/169.3
• 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 2300/0842 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 2310/0254 Control of polarity reversal in general, other than for liquid crystal displays
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

There is provided a circuit for driving an organic light emitting diode (OLED). The circuit includes a current source for providing current to a first terminal of the OLED, and a generator for providing a variable voltage signal to a second terminal of the OLED to facilitate control of the current.

Claims

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

a current drive transistor for providing current to a first terminal of said OLED;

a capacitor for storing a preset voltage and a data voltage to control said current drive transistor, wherein said capacitor is connected to said first terminal;

a data transistor for adding said data voltage onto said capacitor; and

a generator for providing a variable voltage signal to a second terminal of said OLED to facilitate said control of said current drive transistor,

wherein said variable voltage signal comprises a voltage level for facilitating said storing of said preset voltage.

2. The circuit of claim 1, wherein said current, when flowing, is substantially independent of a threshold voltage of said current drive transistor.

3. The circuit of claim 1, wherein said preset voltage and said data voltage are relative to a data reference voltage.

4. The circuit of claim 1, wherein said variable voltage signal further comprises a voltage level that facilitates said storing of said data voltage.

5. The circuit of claim 1, wherein said OLED has a capacitance that facilitates said storing of said preset voltage and said data voltage.

6. The circuit of claim 1, wherein said variable voltage signal comprises a voltage level for turning off said OLED.

7. The circuit of claim 1, wherein said variable voltage signal comprises a voltage level for facilitating said storing of said data voltage.

8. The circuit of claim 1, wherein said variable voltage signal comprises a voltage level for allowing luminance of said OLED.

9. The circuit of claim 1, wherein said variable voltage signal comprises a voltage level for reversing a voltage polarity across said OLED.

10. The circuit of claim 1, wherein said variable voltage signal comprises a voltage level for reversing a source to drain voltage polarity of said current drive transistor.

11. The circuit of claim 1, wherein said variable voltage signal comprises a voltage level for reversing a gate to drain voltage polarity of said current drive transistor.

12. The circuit of claim 1, wherein said current drive transistor and said data transistor are amorphous silicon transistors.

13. A circuit for driving an organic light emitting diode (OLED), comprising:

a current drive transistor for providing current to a first terminal of said OLED;

a capacitor for storing a preset voltage and a data voltage to control said current drive transistor, wherein said capacitor is connected to said first terminal;

a data transistor for adding said data voltage onto said capacitor;

a generator for providing a variable voltage signal to a second terminal of said OLED to facilitate said control of said current drive transistor; and

a data reference voltage transistor for establishing a data reference voltage,

wherein said preset voltage and said data voltage are referenced to said data reference voltage.

14. The circuit of claim 13, wherein a preset signal controls operation of said data reference voltage transistor.

15. The circuit of claim 14,

wherein said circuit is a member of a plurality of circuits in an array of rows and columns, and

wherein said preset signal is provided to said plurality of circuits.

16. The circuit of claim 14,

wherein said circuit is in a row of an array that contains a plurality of such circuits, and

wherein said preset signal is provided from a gate line signal that is used by another row in said array.