Organic light emitting display device and method of driving the same

Patent metadata

Field	Value
Publication number	US-10580338-B2
Application number	US-201816185947-A
Country	US
Kind code	B2
Filing date	Nov 9, 2018
Priority date	Nov 16, 2017
Publication date	Mar 3, 2020
Grant date	Mar 3, 2020

Abstract

An organic light emitting display device includes a display panel including a plurality of active pixels in a display region, and a plurality of test pixels in a non-display region, a panel driver configured to provide the test pixels with data signals corresponding to a plurality of gray levels, and to drive the display panel, a readout circuit configured to measure sensing currents flowing through the test pixels, and a controller configured to obtain hysteresis characteristic values of the test pixels based on the sensing currents, to generate output image data by compensating input image data for the active pixels based on the hysteresis characteristic values of the test pixels to which the active pixels are mapped, and to control the panel driver to display an image based on the output image data.

First claim

What is claimed is:

1. An organic light emitting display device comprising:
a display panel comprising a plurality of active pixels in a display region, and a plurality of test pixels in a non-display region;
a panel driver configured to provide the test pixels with data signals corresponding to a plurality of gray levels, and to drive the display panel;
a readout circuit configured to measure sensing currents flowing through the test pixels; and
a controller configured to obtain hysteresis characteristic values of the test pixels based on the sensing currents, to generate output image data by compensating input image data for the active pixels based on the hysteresis characteristic values of the test pixels to which the active pixels are mapped, and to control the panel driver to display an image based on the output image data.

2. The organic light emitting display device of claim 1 , wherein the hysteresis characteristic values correspond to current differences between the sensing currents and target currents.

3. The organic light emitting display device of claim 2 , wherein the test pixels are grouped into first through N-th test groups, where N is an integer that is greater than 1, and
wherein each test group comprises a reference test pixel for receiving a data signal corresponding to a reference gray level, a first group for alternately receiving the data signal corresponding to the reference gray level and a data signal corresponding to a black gray level, and a second group for alternately receiving the data signal corresponding to the reference gray level and a data signal corresponding to a white gray level.

4. The organic light emitting display device of claim 3 , wherein a gray value for a first pixel of the active pixels in a current period is extracted from the input image data, and a selected test group corresponding to the first pixel is selected among the first through N-th test groups based on the gray value in the current period,
wherein a selected one of the first group and the second group of the selected test group is further selected by comparing the gray value in the current period and a gray value in a previous period before the current period, and
wherein the test pixel to which the first pixel is mapped is updated from a previous test pixel to an updated test pixel in the selected one of the first group and the second group such that the updated test pixel has a closest current difference to a current difference of the previous test pixel among current differences of the test pixels in the selected one of the first group and the second group.

5. The organic light emitting display device of claim 3 , wherein a gray value for a first pixel of the active pixels is extracted from the input image data, and a selected test group corresponding to the first pixel is selected among the first through N-th test groups based on the gray value, and
wherein, when the gray value for the first pixel is maintained for a reference period of time, the test pixel to which the first pixel is mapped is updated to the reference test pixel of the selected test group.

6. The organic light emitting display device of claim 1 , wherein the controller comprises:
a target current storage configured to store target currents corresponding to the plurality of gray levels;
a current difference calculator configured to calculate current differences between the sensing currents and the target currents;
a compensation information storage configured to store the current differences of the test pixels; and
a data compensator configured to obtain compensation values for the active pixels based on the current differences of the test pixels to which the active pixels are mapped, and to compensate the input image data based on the compensation values.

7. The organic light emitting display device of claim 6 , wherein the compensation information storage comprises:
a mapping table configured to store identifiers of the test pixels to which the active pixels are mapped; and
a hysteresis characteristic table configured to store the current differences of the test pixels having the identifiers.

8. The organic light emitting display device of claim 7 , wherein the current difference of each test pixel comprises a first current difference obtained at a first sensing reference voltage and a second current difference obtained at a second sensing reference voltage that is different from the first sensing reference voltage.

9. The organic light emitting display device of claim 1 , wherein the non-display region surrounds the display region.

10. The organic light emitting display device of claim 1 , wherein the non-display region is adjacent to at least one edge of the display region.

11. The organic light emitting display device of claim 1 , wherein the readout circuit is configured to measure the sensing currents every frame period, and
wherein the test pixels to which the active pixels are mapped are configured to be updated every frame period.

12. The organic light emitting display device of claim 1 , wherein the readout circuit is configured to measure the sensing currents with an interval of a plurality of frame periods, and
wherein the test pixels to which the active pixels are mapped are configured to be updated with the interval of the plurality of frame periods.

13. A method of driving an organic light emitting display device comprising a display panel, a panel driver, a readout circuit, a plurality of active pixels in a display region, and a plurality of test pixels in a non-display region, the method comprising:
providing the test pixels with data signals corresponding to a plurality of gray levels and driving the display panel with the panel driver;
measuring sensing currents flowing through the test pixels with the readout circuit;
obtaining hysteresis characteristic values of the test pixels based on sensing currents flowing through the test pixels;
generating output image data by compensating input image data for the active pixels based on the hysteresis characteristic values of the test pixels to which the active pixels are mapped; and
displaying an image based on the output image data.

14. The method of claim 13 , wherein the hysteresis characteristic values correspond to current differences between the sensing currents and target currents.

15. The method of claim 13 , wherein the test pixels are grouped into first through N-th test groups, where N is an integer that is greater than 1, and
wherein each test group comprises a reference test pixel that receives a data signal corresponding to a reference gray level, a first group that alternately receives the data signal corresponding to the reference gray level and a data signal corresponding to a black gray level, and a second group that alternately receives the data signal corresponding to the reference gray level and a data signal corresponding to a white gray level.

16. The method of claim 15 , further comprising:
extracting a gray value for a first pixel of the active pixels in a current period from the input image data;
selecting a test group corresponding to the first pixel among the first through N-th test groups based on the gray value in the current period;
selecting one of the first group and the second group of the selected test group by comparing the gray value in the current period and a gray value in a previous period before the current period; and
updating the test pixel to which the first pixel is mapped from a previous test pixel to a updated test pixel in the selected one of the first group and the second grou

Assignees

• Samsung Display Co Ltd

Inventors

• Park Jinwoo

Classifications

• G09G3/3275 Primary

  Details of drivers for data electrodes · CPC title

• G09G2360/18

  Use of a frame buffer in a display terminal, inclusive of the display panel · CPC title

• G09G2360/16

  Calculation or use of calculated indices related to luminance levels in display data · CPC title

• G09G2300/0413

  Details of dummy pixels or dummy lines in flat panels · CPC title

• G09G2300/0819

  used for counteracting undesired variations, e.g. feedback or autozeroing · CPC title