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1. WO2009011767 - REDUCED POWER CONSUMPTION IN OLED DISPLAY SYSTEM

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[ EN ]
CLAIMS:

1. A method of controlling a passive matrix display having rows and columns of pixels comprising:
a. receiving an input image signal;
b. determining drive signals for at least a first image field and a second image field;
c. calculating a value that is correlated to a change in the total capacitive charge of the pixels that will occur between the display of the first image field and the second image field for at least one column of the passive-matrix, electro-luminescent display;
d. adjusting at least one of the drive signals within first or second image fields to compensate for the change in total capacitive charge; and
e. providing adjusted drive signals for each pixel.

2. A passive matrix, electro-luminescent display system for receiving an input image signal, processing such input image signal, and displaying such processed image with reduced power consumption, comprising:
a. a passive matrix, electro-luminescent display having an array of column electrodes, an array of row electrodes oriented orthogonal to the array of column electrodes and a thin film electro-luminescent layer located between the array of column electrodes and the array of row electrodes, the intersection of each column and row electrode forming an individual light-emitting element (pixel) having an effective capacitor;
b. one or more row drivers for receiving current from one or more row electrodes within the array of row electrodes;
c. one or more column drivers for providing current to the column electrodes within the array of column electrodes to charge the capacitor of the light-emitting elements and provide a drive current to the light-emitting elements; and d. a display driver for receiving the input image signal and processing this input image signal to provide signals to the one or more column drivers corresponding to the electrical charge to be provided by the column driver during the display of a plurality of image fields, wherein the display driver:
i. receives the input image signal;
ii. determines column drive signals for at least a first image field and a second image field;
iii. calculates a value that is correlated to a change in the a capacitive charge of the capacitors that will occur between the display of the first image field and the second image field for at least one column of the passive-matrix, electro-luminescent display;
iv. adjusts at least one of the column drive signals within first or second image fields to compensate for the change in total capacitive charge; and
v. provides adjusted column drive signals for each pixel.

3. The passive matrix, electro-luminescent display system of claim 2, wherein the column driver provides drive signals that do not include a precharge or discharge state.

4. The passive matrix, electro-luminescent display system of claim 2, wherein the capacitors have a capacitance is at least 50 pF per square mm.

5. The passive matrix, electro-luminescent display system of claim 2, wherein the capacitors have a capacitance is at least 200 pF per square mm.

6. The passive matrix, electro-luminescent display system of claim 2, wherein the total thickness of the thin film electro-luminescent layer is less than 5000A.

7. The passive matrix, electro-luminescent display system of claim 2, wherein the dielectric constant of the thin film electro-luminescent layer is greater than 2.

8. The passive matrix, electro-luminescent display system of claim 2, wherein the electric charge provided by a column driver to display one image field is controlled through time division multiplexing.

9. The passive matrix, electro-luminescent display system of claim 8, wherein the time that the total current is provided during the display of the first image field is reduced to reduce the electric charge to compensate for the discharge of the capacitive charge of a column of the display between the display of a first and second image field occurs.

10. The passive matrix, electro-luminescent display system of claim 8, wherein the row drivers provide a programmable current sink and wherein this current sink is programmed to control the source current provided by the column drivers.

11. The passive matrix, electro-luminescent display system of claim 10, wherein the current sinks in the row drivers are programmed to limit the current of the column drivers such that at least one of the one or more column drivers provides a constant current to at least one column electrode for the entire image field time.

12. The passive matrix, electro-luminescent display system of claim 2, wherein the column driver includes programmable current sources.

13. The passive matrix, electro-luminescent display system of claim 12, wherein the column driver controls the amplitude of the current to adjust for a change in total capacitive charge of a column of the display between the display of a first and second image field.

14. The passive matrix, electro-luminescent display system of claim 2, wherein groups of multiple rows and columns of light-emitting elements are simultaneously controlled.

15. The passive matrix, electro-luminescent display system of claim 14, wherein the row drivers provide separate signals at different times to different groups of row electrodes within the array of row electrodes, such that the row drivers simultaneously provide at least two different level signals to the array of row electrodes.

16. The passive matrix, electro-luminescent display system of claim 14, wherein during the processing the input image signal to provide column drive signals, the display driver, presharpens the input image signal.

17. The passive matrix, electro-luminescent display system of claim 14, wherein the luminance output for light-emitting elements within each group of multiple rows of light-emitting elements, is distributed such that the luminance output of light-emitting elements at or near the center of the group of multiple rows, is higher than the luminance output of light-emitting elements of other light-emitting elements, within each group of multiple rows.

18. The passive matrix, electro-luminescent display system of claim 14, wherein each group of multiple rows of light-emitting elements includes at least three rows of light-emitting elements.

19. The passive matrix, electro-luminescent display system of claim 16, wherein the luminance output for light-emitting elements within each group of multiple rows of light-emitting elements is distributed such that the luminance output of light-emitting elements decreases, increases, and finally decreases again as the distance from the center of the group of multiple rows of light-emitting elements is increased.

20. The passive matrix, electro-luminescent display system of claim 14, wherein a first group of rows of light-emitting elements are
simultaneously controlled during a first image field time and a second group of rows of light-emitting elements are simultaneously controlled during a second image field and wherein the first group of rows of light-emitting elements overlap the second first group of rows of light-emitting elements with the exception of one row of light-emitting elements, such as to reduce the change in total capacitive charge for any light-emitting element within the display device between the first and second image field time.