Display methods and apparatus

• US 7,755,582 B2
• Filed: 01/06/2006
• Issued: 07/13/2010
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Pixtronix, Incorporated (Qualcomm, Inc.)
• Inventors: Barton, Roger, Lewis, Stephen, Hagood, Nesbitt W., McAllister, Abraham
• Primary Examiner(s): Hjerpe; Richard
• Assistant Examiner(s): Said; Mansour M
• Application Number:
  US11/326,962
• Publication Number:
  US 20060187191A1
• Time in Patent Office: 1,649 Days
• Field of Search: 345/48, 345 83- 84, 345 87- 88, 345/90, 345/92, 345 95- 96, 345/100, 345108-109, 345/55, 345/201, 345/214, 315/169.3, 359/198, 359/214, 359/224, 359/227, 359/290, 359/295, 359/298
• US Class Current: 345/84
• CPC Class Codes: G02B 26/04 by periodically varying the intensity of light, e.g. using choppers shutters, diaphragms for cameras G03B9/00; devices for eliminating or reducing the effect of flicker in projection systems G03B21/40
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/088 using a non-linear two-terminal element
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2310/063 Waveforms for resetting the whole screen at once
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833

Abstract

The invention relates to methods and apparatus for forming images on a display utilizing a control matrix to control the movement of MEMs-based light modulators.

Claims

1. A display apparatus comprising:

an array of pixels including

a transparent substrate, and

a plurality of MEMS-based light modulators; and

a control matrix disposed on the substrate including, for a pixel in the array of pixels, i) a write-enabling interconnect for enabling the pixel to respond to a data voltage, ii) an actuation voltage interconnect for providing a voltage sufficient to actuate the pixel, iii) a first switch for selectively governing the application of the voltage provided by the actuation voltage interconnect to the pixel, and iv) a data voltage interconnect for controlling the first switch, thereby regulating the application of the actuation voltage across an actuator included in a respective light modulator, thereby empowering the light modulator to change states to form an image.

2. The display apparatus of claim 1, comprising:

an actuation voltage source for providing a voltage to the actuation voltage interconnect;

a data voltage source for providing a voltage to the data voltage interconnect, wherein the voltage provided by the actuation voltage source is greater than the voltage provided by the data voltage source.

3. The display apparatus of claim 2, wherein the actuation voltage source provides a voltage that at least about 4 times greater than the voltage provided by the data voltage source.

4. The display apparatus of claim 1, comprising, for the pixel, a second data voltage interconnect for controlling a second switch, wherein application of a predetermined voltage to the first data voltage interconnect empowers the light modulator to enter a first state and the application of a predetermined voltage to the second data voltage interconnect empowers the light modulator to enter a second state.

5. The display apparatus of claim 1, wherein the light modulators include an elastic member to return the light modulator to a rest state in the absence of the application of the actuation voltage.

6. The display apparatus of claim 1, comprising, for the pixel, a memory element for storing an intended light modulator state.

7. The display apparatus of claim 6, wherein the memory element stores a current intended light modulator state.

8. The display apparatus of claim 6, wherein the memory element stores a subsequent intended light modulator state.

9. The display apparatus of claim 6, wherein the memory element comprises a capacitor.

10. The display apparatus of claim 9, wherein the light modulator changes state in response to a discharging of the capacitor.

11. The display apparatus of claim 6, wherein the memory element stores the data voltage applied to the data interconnect.

12. The display apparatus of claim 6, wherein the memory element comprises one of a SRAM and a DRAM circuit.

13. The display apparatus of claim 1, wherein a plurality of pixels in the array of pixels share a common actuation voltage interconnect.

14. The display apparatus of claim 1, wherein the pixel comprises a resistor positioned between the actuation voltage interconnect and the first switch.

15. The display apparatus of claim 1, wherein the first switch comprises a transistor.

16. The display apparatus of claim 1, wherein the first switch comprises varistor.

17. The display apparatus of claim 1, wherein the switch comprises a MIM diode.

18. The display apparatus of claim 1, wherein a plurality of pixels in the array of pixels are arranged to form a scan line, and wherein the pixels in the scan line share the write-enable interconnect.

19. The display apparatus of claim 1, wherein empowering comprises actuating the actuator.

20. The display apparatus of claim 1, wherein empowering comprises substantially reducing an additional minimum voltage change needed to actuate the actuator.

21. The display apparatus of claim 20, wherein the control matrix comprises a global actuation interconnect for causing at least the additional minimum voltage change to a plurality of pixels in the array of pixels.

22. The display apparatus of claim 1, comprising a global actuation interconnect for initiating actuation of the empowered actuators.

23. The display apparatus of claim 1, wherein the light modulator comprises a shutter-based light modulator.

24. The display apparatus of claim 23, wherein the shutter-based light modulator comprises a shutter configured for motion parallel to the substrate.

25. The display apparatus of claim 23, wherein the states of the light modulator include an open state and a closed state.

26. The display apparatus of claim 1, wherein the substrate comprises a transparent substrate.

27. A display apparatus comprising:

an array of pixels including

a substrate having a plurality of apertures, and

a plurality of shutters corresponding to the plurality of apertures;

wherein a shutter has at least one mechanical support substantially limiting a range of motion of the shutter to a movement plane that is parallel to a plane defined by the substrate; and

a control matrix disposed on the substrate including, for a pixel in the array of pixels, i) a write-enabling interconnect for enabling the pixel to respond to a data voltage, ii) an actuation voltage interconnect for providing a voltage sufficient to actuate the pixel, iii) a first switch for selectively governing the application of the voltage provided by the actuation voltage interconnect to the pixel, and iv) a data voltage interconnect for controlling the first switch, thereby regulating the application of the actuation voltage across an actuator connected to a respective shutter and empowering an electrostatically driven movement of the respective shutter substantially within the movement plane.

28. A method of forming an image on a display comprising:

applying a write-enabling voltage to a plurality of pixels arranged in a scan line;

applying an actuation voltage to at least one of the pixels in the scan line;

selectively applying a data voltage to a switch corresponding to a pixel in the scan line to regulate the application of the actuation voltage to an actuator in the pixel, thereby controlling the state of a MEMS-based light modulator incorporating the actuator that corresponds to the thin film transistor, wherein the actuation voltage is at least twice the data voltage.

29. The method of claim 28, wherein the actuation voltage is at least about 4 times greater than the data voltage.

30. The method of claim 28, comprising grounding the actuator, thereby allowing an elastic restoring force to drive the MEMS-based light modulator into a rest state.

31. The method of claim 28, comprising storing an intended state of the MEMS-based light modulator at the pixel.

32. The method of claim 31, wherein storing the intended state of the MEMS-based light modulator comprises charging a capacitor.

33. The method of claim 31, wherein storing the intended state of the MEMS-based light modulator comprises discharging a capacitor.

34. The method of claim 31, wherein storing the intended state of the MEMS-based light modulator comprises storing the shutter position in one of a SRAM circuit and a DRAM circuit incorporated into the pixel.

35. The method of claim 31, wherein the memory element stores a subsequent intended state of the MEMS-based light modulator.

36. The method of claim 31, wherein storing the intended state of the MEMS-based light modulator comprises storing the data voltage applied to the switch.

37. The method of claim 28, comprising applying a global actuation voltage to a plurality of pixels in the array of pixels.

38. The method of claim 28, wherein the MEMS-based light modulator comprises a shutter-based light modulator.

39. The method of claim 38, wherein the shutter-based light modulator comprises a shutter configured for motion parallel to the substrate.

40. The method of claim 38, wherein the intended state of the shutter-based light modulator is one of an open state and a closed state.