Method and system for writing data to MEMS display elements

• US 20070126673A1
• Filed: 12/07/2005
• Published: 06/07/2007
• Est. Priority Date: 12/07/2005
• Status: Abandoned Application

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Inventors: Lewis, Alan, Cummings, William, Mignard, Marc, Djordjev, Kostadin, Hastings, R.
• Application Number:
  US11/296,656
• Publication Number:
  US 20070126673A1
• Time in Patent Office: Days
• US Class Current: 345/84
• CPC Class Codes: G09G 2300/06 Passive matrix structure, i.e. with direct application of both column and row voltages to the light emitting or modulating elements, other than LCD or OLED
• CPC Class Codes: G09G 2310/0254 Control of polarity reversal in general, other than for liquid crystal displays
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/0204 Compensation of DC component across the pixels in flat panels
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 3/2051 with use of a spatial dither pattern
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

Charge balanced display data writing methods use write and hold cycles of opposite polarity during selected frame update periods. Spatial dithering of hold cycle signals can reduce flicker.

Claims

1. A method of writing frames of display data to an array of microelectromechanical system (MEMS) display elements, said method comprising:

writing display data to said MEMS display elements to display an image;

applying a first series of bias voltages of alternating polarity to a first set of columns or rows of the array of MEMS display elements; and

applying a second series of bias voltages of alternating polarity to a second set of columns or rows of the array of MEMS display elements;

wherein said first set of columns or rows is interleaved with said second set of columns or rows such that adjacent columns or rows receive bias voltages of opposite polarity during said applying of the first series and said applying of the second series.

2. The method of claim 1, wherein the first and second series are applied to the first and second sets of columns or rows, respectively in an ABAB or an ABBA pattern, wherein A represents a column or row of the first set and B represents a column or row of the second set.

3. The method of claim 1, further comprising:

applying a third series of bias voltages of alternating polarity to a third set of columns or rows of the array of MEMS display elements; and

applying a fourth series of bias voltages of alternating polarity to a fourth set of columns or rows of the array of MEMS display elements.

4. The method of claim 3, wherein the first and second series are applied to first and second sets of columns, and the third and fourth series are applied to third and fourth sets of rows.

5. The method of claim 1, wherein the displayed image is maintained while the first and second series are applied.

6. The method of claim 1, wherein each of the elements changes from having a first light modulation characteristic to having a second light modulation characteristic in response to the application of the first and second series.

7. The method of claim 6, wherein the first and second light modulation characteristics are slightly different.

8. The method of claim 1, wherein actuated elements remain actuated and unactuated elements remain unactuated while the first and second series are applied.

9. The method of claim 1, wherein the bias voltages minimize charging of the elements.

10. The method of claim 1, wherein said first and second series of voltages are applied substantially contemporaneously.

11. A method of reducing flicker during a display hold-mode in a bistable display, said method comprising applying bias potentials of opposite polarity to adjacent rows and/or adjacent columns of the display.

12. The method of claim 11, wherein the bias potentials are applied such that hold mode flicker is spatially dithered.

13. The method of claim 12, wherein the flicker is spatially dithered in at least one of the row direction, the column direction, and both the row and the column direction.

14. The method of claim 11, wherein a first series of bias potentials of opposite polarity is applied to rows of the display and a second series of bias potentials is applied to columns of the display.

15. The method of claim 11, wherein the bias potentials minimize charging of the elements.

16. The method of claim 11, wherein said first and second series of voltages are applied substantially contemporaneously.

17. A method of driving a plurality of bistable microelectromechanical system (MEMS) display devices, the method comprising:

writing image data to the devices to display an image;

applying hold signals to the display devices, wherein the hold signals are applied to sets of display devices so as to spatially dither differences in light output such that visible flicker is reduced in said display devices during said applying, wherein the differences in light output are caused by the application of the hold signals.

18. The method of claim 17, wherein the hold signals comprise signals of at least one of opposite polarity and different amplitude.

19. The method of claim 18, wherein adjacent sets receive hold signals differing by at least one of polarity and amplitude.

20. The method of claim 17, wherein the sets comprise at least one of rows, columns, portions of rows, portions of columns, portions of multiple rows, and portions of multiple columns.

21. The method of claim 17, wherein the sets are contiguous.

22. The method of claim 17, wherein the sets are not contiguous.

23. A display device comprising:

an array of microelectromechanical system (MEMS) display elements; and

a display driver configured to supply signals to rows and columns of the array so as to display an image, to apply a first series of bias voltages of alternating polarity to a first set of columns or rows of the array, and to apply a second series of bias voltages of alternating polarity to a second set of columns or rows,

wherein said first set of columns or rows is interleaved with said second set of columns or rows such that adjacent columns or rows receive bias voltages of opposite polarity during said applying of the first series and said applying of the second series.

24. The device of claim 23, wherein the driver is further configured to apply a third series of bias voltages of alternating polarity to a third set of columns or rows of the array of MEMS display elements, and to apply a fourth series of bias voltages of alternating polarity to a fourth set of columns or rows of the array of MEMS display elements.

25. The device of claim 23, wherein the first and second series are applied to first and second sets of columns, and the third and fourth series are applied to third and fourth sets of rows.

26. The device of claim 23, wherein each of the elements is configured to change from having a first light modulation characteristic to having a second light modulation characteristic in response to the application of the first and second series.

27. The device of claim 23, wherein the array is configured such that actuated elements remain actuated and unactuated elements remain unactuated while the first and second series are applied.

28. The method of claim 23, wherein said first and second series of voltages are applied substantially contemporaneously.

29. A display device comprising:

means for displaying an image;

means for supplying signals to rows and columns of the displaying means so as to display an image;

means for applying a first series of bias voltages of alternating polarity to a first set of portions of the displaying means; and

means for applying a second series of bias voltages of alternating polarity to a second set of portions of the displaying means,

wherein said first set of portions is interleaved with said second set of portions such that adjacent portions of the displaying means receive bias voltages of opposite polarity during said applying of the first series and said applying of the second series.

30. The device of claim 29, wherein the supplying means is further configured to apply a third series of bias voltages of alternating polarity to a third set of portions of the displaying means, and to apply a fourth series of bias voltages of alternating polarity to a fourth set of portions of the displaying means.

31. The device of claim 29, wherein each of the portions of the displaying means is configured to change from having a first light modulation characteristic to having a second light modulation characteristic in response to the application of the first and second series.

32. The device of claim 29, wherein the displaying means is configured such that actuated portions of the displaying means remain actuated and unactuated portions of the displaying means remain unactuated while the first and second series are applied.