Driving circuit for current programmed organic light-emitting diode displays

• US 20060208961A1
• Filed: 02/09/2006
• Published: 09/21/2006
• Est. Priority Date: 02/10/2005
• Status: Active Grant

• Current Assignee: IGNIS Innovation Incorporated
• Original Assignee: IGNIS Innovation Incorporated
• Inventors: Chali, Gholamreza Reza, Nathan, Arokia
• Granted Patent: US 10,078,984 B2
• Time in Patent Office: Days
• US Class Current: 345/44
• CPC Class Codes: G09G 2310/0248 Precharge or discharge of column electrodes before or after applying exact column voltages
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2330/06 Handling electromagnetic interferences [EMI], covering emitted as well as received electromagnetic radiation
• CPC Class Codes: G09G 3/3241 the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror
• CPC Class Codes: G09G 3/3283 in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H05B 45/00 Circuit arrangements for operating light-emitting diodes [LED]
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A load driving circuit for a load having a parasitic capacitance associated therewith is provided. The load being current programmed. The driving circuit has a data line having a voltage controlling the load, a feedback loop having a lowpass filter for monitoring the voltage of the data line; and a current source for providing a current to the data line; the current source being controlled by a signal line and an output from the lowpass filter.

Claims

1. A load driving circuit for a load having a parasitic capacitance associated therewith and being current programmed, the driving circuit comprising:

a data line having a voltage controlling the load;

a feedback loop having a lowpass filter for monitoring the voltage of the data line; and

a current source for providing a current to the data line;

the current source being controlled by a signal line and an output from the lowpass filter.

2. The load driving circuit according with claim 1 wherein the lowpass filter comprises a so-called Butterworth filter and a differentiator.

3. The load driving circuit according to claim 1 wherein the current source is a voltage controlled current source (VCCS).

4. A driving circuit for a light emitting diode that is current programmed and having a parasitic capacitance, the driving circuit comprising:

a data line controlling the light emitting diode;

a low pass filter monitoring the voltage of the data line; and

a current source for providing a current to the data line;

the current source being controlled by a signal line and an output from the lowpass filter.

5. The driving circuit according with claim 4 wherein the lowpass filter comprises a so called Butterworth filter and a differentiator.

6. The driving circuit according to claim 4 wherein the current source is a voltage controlled current source (VCCS).

7. The driving circuit according to claim 4 wherein the light emitting diode is an organic light emitting diode.

8. The driving circuit according to claim 4, wherein an illumination of the light emitting diode is responsive to the current provided by the data line.

9. The driving circuit according to claim 4, wherein the light emitting diode is controlled by a thin film transistor.

13. A display having an array of pixels each including an organic light emitting diode wherein the diode is driven by a driving circuit according to claim 4.

10. A driving circuit for a light emitting diode that is current programmed and having a parasitic capacitance, the driving circuit comprising:

a data line controlling the light emitting diode;

a feedback loop comprising;

an analogue to digital converter; and

a controller running an algorithm that provides low pass filter functionality to the feedback loop; and

a current source for providing a current to the data line;

the current source receiving input from a digital to analogue converter that receives input from the controller.

11. The driving circuit according to claim 10 wherein the current source is a voltage controlled current source (VCCS).

12. The driving circuit according to claim 10 wherein the light emitting diode is an organic light emitting diode.

14. A display having an array of pixels each including an organic light emitting diode wherein the diode is driven by a driving circuit according to claim 10.

15. A method of driving a light emitting diode in a display, the light emitting diode having a parasitic capacitance and being current programmed, the method comprising the steps of:

providing a current to the light emitting diode, the current being provided by a current source;

monitoring a voltage of a data line providing the current to the light emitting diode with a low pass filter; and

mixing the voltage and a data line signal to form an input;

providing the input to the current source.

16. The method according to claim 15, wherein the current source is a voltage controlled current source (VCCS).

17. The method according to claim 15, wherein the light emitting diode is an organic light emitting diode.