Organic light emitting display and method for driving the same

• US 20090058772A1
• Filed: 05/20/2008
• Published: 03/05/2009
• Est. Priority Date: 09/04/2007
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Baek-Woon
• Granted Patent: US 8,497,827 B2
• Time in Patent Office: Days
• US Class Current: 345/82
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

A method of driving an organic light emitting display device includes generating a luminance map for a plurality of pixels by applying the same driving voltage to driving transistors formed in the plurality of pixels of a panel and by capturing luminances of the pixels, generating a threshold voltage map by calculating threshold voltage correction values that compensate for threshold voltages of the driving transistors associated with the luminances of the pixels. A lookup table is generated by sampling the threshold voltage correction values stored in the threshold voltage map. Threshold voltage correction values are restored by interpolating the sampled threshold voltage correction values, and correcting a driving voltage by adding the restored threshold voltage correction values to input gray level data and by providing the added value to the panel.

Claims

1. A method of driving an organic light emitting display device, comprising:

generating a luminance map for a plurality of pixels by applying a driving voltage having a common magnitude to driving transistors associated with the plurality of pixels of a display panel and capturing a luminance of the pixels;

generating a threshold voltage map by calculating threshold voltage correction values that compensate for threshold voltage variation of the driving transistors corresponding to the luminances of the pixels;

generating a lookup table by sampling the threshold voltage correction values stored in the threshold voltage map;

restoring the threshold voltage correction values by interpolating the sampled threshold voltage correction values; and

correcting a driving voltage by adding the restored threshold voltage correction values to input gray level data and by providing the added value to the panel.

2. The method of claim 1, wherein the panel is an organic light emitting display panel that includes an organic light emitting display element driven by the driving transistor.

3. The method of claim 2, wherein generating the lookup table comprises sampling the plurality of pixels on a grid basis and storing the threshold voltage correction values corresponding to the sampled pixels in the lookup table.

4. The method of claim 3, wherein generating the threshold voltage map comprises:

calculating the threshold voltages corresponding to the luminances of the pixels by using correlation between the luminances of the pixels and the threshold voltages of the driving transistors formed in the pixels;

implementing gamma correction such that the input gray level data has a substantially linear relation with gray level voltages applied to the driving transistors; and

scaling the gray level voltages corresponding to the gray level data to generate gamma-corrected threshold voltages as the threshold voltage correction values and to generate the threshold voltage correction values as the threshold voltage map.

5. The method of claim 4, wherein generating the threshold voltage map further comprises removing noise included in the luminance map by noise filtering or geometric correction.

6. The method of claim 2, wherein restoring the threshold voltage correction values is implemented by bilinear interpolation.

7. The method of claim 2, wherein generating the luminance map comprises applying a driving voltage corresponding to a black gray level to the driving transistors before applying the same driving voltage to the driving transistors.

8. The method of claim 4, wherein correcting the driving voltage comprises:

implementing gamma correction such that the input gray level data has a substantially linear relation with the gray level voltages; and

scaling the input gray level data and adding the scaled gray level data to the threshold voltage correction values.

9. A method of driving an organic light emitting display device, comprising:

calculating a threshold voltage correction value that compensates for a threshold voltage of each driving transistor from a luminance map for an organic light emitting display panel in which driving transistors are formed;

sampling and storing the calculated threshold voltage correction value on a grid basis;

restoring the threshold voltage correction value for each driving transistor from the sampled threshold voltage correction value by bilinear interpolation; and

adding the restored threshold voltage correction value to input gray level data and applying the added value to the driving transistor.

10. An organic light emitting display device, comprising:

an organic light emitting display panel having a plurality of organic light emitting display elements each having an associated driving transistor;

a threshold voltage decoder comprising a lookup table in which threshold voltage correction values of the driving transistors are sampled and stored, and restores the threshold voltage correction values of the driving transistors from the sampled threshold voltage correction values; and

an adder that adds the threshold voltage correction values to input gray level data and provides the added values to the organic light emitting display panel.

11. The organic light emitting display device of claim 10, further comprising a counter that generates a counting signal to output sampled threshold voltage correction values from the lookup table and provides the generated counting signal to the threshold voltage decoder.

12. The organic light emitting display device of claim 10, wherein the threshold voltage decoder restores the threshold voltage correction values of the driving transistors by bilinear interpolation.

13. The organic light emitting display device of claim 12, further comprising:

a gamma corrector that implements gamma correction such that a variation of the input gray level data has a substantially linear relation with a variation of gray level voltages; and

a scaler that scales the gamma-corrected input gray level data and provides the scaled data to the adder.