ACTIVE MATRIX ORGANIC LIGHT-EMITTING DIODE DISPLAY AND METHOD FOR DRIVING THE SAME

• US 20130141469A1
• Filed: 12/01/2011
• Published: 06/06/2013
• Est. Priority Date: 12/01/2011
• Status: Active Grant

• Current Assignee: Chihao Xu
• Original Assignee: Chihao Xu
• Inventors: XU, Chihao
• Granted Patent: US 8,743,160 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2081 with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element

Abstract

In one exemplary embodiment, a method for driving an AMOLED display having OLED arranged in rows and columns, a pixel circuit for driving an OLED, a scan line for selecting the pixel circuits of each row and a data line for controlling the pixel circuits of each column and supply lines connectable to the anodes and cathodes of the AMOLED pixels may be described. The method may be steps for decomposing image data into a plurality of subframes based on a dependence of physical characteristics of the AMOLED display; generating binary subframe signals according to the decomposed subframes; activating an OLED, based on a scan signal on the scan line and a generated subframe signal applied on the data line, allowing or blocking a current to flow through the organic light emitting diode; and connecting the supply lines to a voltage source for a predetermined duration for each subframe.

Claims

1. A method for driving an active matrix organic light-emitting diode (AMOLED) display having organic light-emitting diodes (OLED) arranged in rows and columns, a pixel circuit for driving an OLED, a scan line for selecting the pixel circuits of each row and a data line for controlling the pixel circuits of each column and supply lines connectable to the anodes and cathodes of the AMOLED pixels, comprising:

decomposing image data into a plurality of subframes based on a dependence of physical characteristics of the AMOLED display;

generating binary subframe signals according to the decomposed subframes;

activating an organic light emitting diode, based on a scan signal on the scan line and a generated subframe signal applied on the data line, allowing or blocking a current to flow via the supply lines through the organic light emitting diode; and

connecting the supply lines to a voltage source for a predetermined duration for each subframe.

2. The method of claim 1, wherein the decomposition of the image depends on the set brightness of the display.

3. The method of claim 1, wherein a voltage value of the voltage source is a function of set brightness of the display.

4. The method of claim 1, further comprising detecting an OLED temperature or temperatures during the operation to adapt at least one of parameters of physical characteristics like current-voltage characteristics of OLEDs, values of trace resistances and a voltage value of the voltage source.

5. The method of claim 1, wherein the binary value subframe is generated by a comparison function with the remaining image data as an input.

6. The method of claim 5, further comprising simulating a pixel-wise luminance distribution of the AMOLED for a given binary subframe to calculate a next remaining image data.

7. The method of claim 6, further comprising considering of electro-optical characteristics of OLEDs and resistance of the supply lines during the simulation of a pixel-wise luminance distribution of the AMOLED display.

15. The method of claim 1, wherein the duration for connecting the supply lines to the voltage source is correlated to the threshold value for obtaining the binary value subframe.

33. The method of claim 4, wherein the binary value subframe is generated by a comparison function with the remaining image data as an input and further comprising simulating a pixel-wise luminance distribution of the AMOLED for a given binary subframe to calculate a next remaining image data.

8. A method for the determination of a sequence of binary-value subframes used for addressing and driving an AMOLED display from a gray-value or a color value image, comprising the steps:

obtaining a binary value subframe from a remaining image by comparing the gray or color values with a predetermined threshold value;

simulating a pixel-wise luminance distribution of the AMOLED display, based on the binary subframe and the predetermined time factor;

subtracting the pixel-wise luminance distribution of the AMOLED display from the actual remaining image data in order to calculate a next remaining image data; and

iterating the above steps with a next remaining image instead of the remaining image.

9. The method of claim 8, further comprising storing the remaining image data after each subframe.

10. The method of claim 9, further comprising that the dissolving of the remaining image data is higher than that of the source image.

11. The method of claim 8, wherein an own threshold value is used for each iteration.

12. The method of claim 8, wherein the thresholds are predetermined in dependence of physical characteristics of the AMOLED display and the set brightness.

13. The method of claim 8, wherein the threshold values are a function of the temperatures of the AMOLED display.

14. The method of claim 8, wherein generation of the subframe for a higher threshold value is prior to that for a lower threshold value.

16. A method for simulating a pixel current distribution of an AMOLED display, wherein the display comprises a matrix of AMOLED pixels, arranged in rows and columns, wherein all AMOLED pixels are driven digitally, wherein all AMOLED pixels in a column are connected to a supply line for that column, wherein at least one end of the supply line is either connected or switched to the voltage source comprising, for a column of AMOLED pixels in the matrix, the steps of:

estimating a value for a voltage/current for a selected node of the column;

calculating at least one of a voltage value and a current value for remaining nodes of the column, based on one of an estimated voltage or current value; and

iterating the previous steps in order to reduce a difference between a calculated voltage or current value and a real voltage or current value at a chosen location of the column.

17. The method according to claim 16, wherein the simulation of the pixel current distribution for a binary subframe is executed during at least one of the addressing and driving phase for this subframe

18. The method according to claim 16, wherein the number of iterations is limited.

19. The method according to claim 16, wherein the number of iterations for each subframe (Bi) depends on the duration of the corresponding time factor (ti).

20. The method according to claim 16, wherein, for a subframe, the calculated pixel current distribution is correlated to the luminance distribution of this subframe.

21. The method according to claim 20, further comprising considering the internal OLED capacitance for the simulation of a pixel-wise luminance distribution of the AMOLED display.

22. The method according to claim 16, further comprising the consideration of supply connections structured in parallel lines with one line for each column.

23. The method according to claim 16, wherein the selected node is at an end of the column.

24. The method of claim 16, further comprising choosing at least one of a node and a position of a current divide in the column.

25. The method according to claim 16, wherein the current-voltage characteristics of an OLED are stored as a lookup table.

26. The method according to claim 16, further comprising estimating a value for at least one of the voltage and current for a selected node of a row.

27. The method according to claim 16, further comprising considering the resistance of the row lines.

28. The method of claim 16, further wherein a pixel current that is at least one of estimated or calculated, is applied for the calculation of an anode potential of the next pixel at a same column and for the calculation of a cathode potential of the next pixel at the same row.

29. A device for driving an active matrix organic light-emitting diode (AMOLED) display, the display comprising organic light-emitting diodes (OLED) arranged in rows and columns, a pixel circuit for driving an OLED, a scan line for selecting the pixel circuits of each row and a data line for controlling the pixel circuits of each column and supply lines connectable to the anodes and cathodes of the AMOLED pixels, comprising:

a circuit that decomposes the image data into several subframes in dependence of the physical characteristics of the AMOLED display;

a circuit that generates binary subframe signals according to the decomposed subframes;

a circuit that activates an organic light emitting diode, based on a scan signal on the scan line and a generated subframe signal applied on the data line, and that allows or blocks a current from flowing through the organic light emitting diode; and

a circuit that connects the supply lines to a voltage source for a predetermined duration for each subframe.

30. A device for the determination of a sequence of binary-value subframes used for addressing/driving an AMOLED display from one of a gray-value or a color value image, comprising:

a circuit that obtains a binary value subframe from one of a gray value or color value remaining image by comparing the gray or color values with a predetermined threshold value;

a circuit that simulates a pixel-wise luminance distribution of the AMOLED display, based on the binary value subframe and a predetermined time factor;

a circuit that subtracts the pixel-wise luminance distribution of the AMOLED display from the remaining image data in order to calculate the next remaining image data.

31. A device for simulating a pixel current distribution of an AMOLED display, wherein the display comprises a matrix of AMOLED pixels, arranged in rows and columns, wherein all AMOLED pixels are driven digitally, wherein all AMOLED pixels in a column are connected to a supply line for that column, wherein at least one end of the supply line is connected/switched to the voltage source,

comprising, for at least one of a column or a row of AMOLED pixels in the matrix:

a circuit that estimates at least one of a voltage or a current for a selected node of the at least column or row;

a circuit that estimates the voltage/current values for the remaining nodes of the at least column or row, based on an estimated value of the voltage or the current;

a circuit that repeats the previous steps in order to reduce the difference between the calculated and the real voltage or current value at a chosen location of the at least column or row.

32. An active matrix organic light-emitting diode (AMOLED) display module comprising:

an active matrix organic light-emitting diodes (OLED) display,

a device that determines a sequence of binary-value subframes used for addressing/driving an AMOLED display from one of a gray-value or a color value image, through simulation of a pixel current distribution of a digitally driven AMOLED display, and

a device that connects the supply lines of an AMOLED display to a voltage source for a predetermined duration for each subframe, wherein at least one supply side of the AMOLED display, anode and/or cathode, is structured in parallel lines with one line for each column/row.