Reduced capacitance display element

• US 8,004,504 B2
• Filed: 06/17/2005
• Issued: 08/23/2011
• Est. Priority Date: 09/27/2004
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Gally, Brian J., Cummings, William J.
• Primary Examiner(s): NGUYEN, KIMNHUNG T
• Application Number:
  US11/155,939
• Publication Number:
  US 20060077153A1
• Time in Patent Office: 2,258 Days
• Field of Search: 345/204, 345/84, 345/85, 359/212, 359/224, 359/530, 359/555, 359/556, 359/584, 359/585
• US Class Current: 345/204
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26

Abstract

A display element, such as an interferometric modulator, comprises a transparent conductor configured as a first electrode and a movable mirror configured as a second electrode. Advantageously, the partial reflector is positioned between the transparent conductor and the movable mirror. Because the transparent conductor serves as an electrode, the partial reflector does not need to be conductive. Accordingly, a greater range of materials may be used for the partial reflector. In addition, a transparent insulative material, such as a dielectric, may be positioned between the transparent conductor and the partial reflector in order to decrease a capacitance of the display element without changing a gap distance between the partial reflector and the movable mirror. Thus, a capacitance of the display element may be reduced without changing the optical characteristics of the display element.

Claims

1. A display element comprising:

a substantially transparent conductive layer;

a partially reflective insulator having a thickness of between about 40 and 150 Angstroms;

a moveable reflective layer, the partially reflective insulator being positioned between the conductive layer and the moveable reflective layer, wherein a voltage applied between the conductive layer and the moveable reflective layer induces movement of the moveable reflective layer; and

a dielectric layer positioned between the conductive layer and the partially reflective insulator, wherein a capacitance of the display element is reduced compared to a display element without the dielectric layer.

2. The display element of claim 1, wherein when the voltage is applied between the conductive layer and the moveable reflective layer, at least a portion of the moveable reflective layer moves so that the at least a portion of the moveable reflective layer physically contacts the partially reflective insulator.

3. The display element of claim 1, further comprising:

a thin dielectric layer positioned between the partially reflective insulator and the moveable reflective layer.

4. The display element of claim 1, wherein the dielectric layer comprises a material selected from the group consisting of:

SiO₂, Al₂O₃, and Silicon Nitride.

5. The display element of claim 1, wherein the partially reflective insulator comprises a material selected from the group consisting of:

Silicon Nitride, CrO₂, CrO₃, Cr₂O₃, Cr₂O, and CrOCN.

6. The display element of claim 1, further comprising a circuit configured to drive the moveable reflective layer such that light reflected by the moveable reflective layer and the partially reflective insulator can be modulated so as to form part of a viewable image.

7. The display element of claim 6, wherein the display element comprises a display element in a reflective display.

8. The display element of claim 1, wherein the display element is included with a plurality of other display elements to form an image by selectively modulating incident light.

9. The display element of claim 1, wherein the moveable reflective layer comprises a metal.

10. A display system comprising:

a display comprising a plurality of display elements, each of the display elements comprising

a substantially transparent conductive layer;

a partially reflective non-conductive layer having a thickness of between about 40 and 150 Angstroms; and

a moveable reflective layer, the partially reflective non-conductive layer being positioned between the conductive layer and the moveable reflective layer, wherein a voltage applied between the conductive layer and the moveable reflective layer induces movement of the moveable reflective layer;

a processor that is in electrical communication with the display, the processor being configured to process image data; and

a memory device in electrical communication with the processor.

11. The display system as recited in claim 10, further comprising:

a first controller configured to send at least one signal to the display; and

a second controller configured to send at least a portion of the image data to the first controller.

12. The display system as recited in claim 10, further comprising:

an image source module configured to send the image data to the processor.

13. The display system as recited in claim 12, wherein the image source module comprises at least one of a receiver, a transceiver, and a transmitter.

14. The display system as recited in claim 10, further comprising:

an input device configured to receive input data and to communicate the input data to the processor.

15. The display system of claim 10, wherein the plurality of display elements comprises a plurality of interferometric modulators.

16. The display system of claim 10, further comprising a circuit configured to drive the moveable reflective layer such that light reflected by the moveable reflective layer and the partially reflective non-conductive layer can be modulated so as to form part of a viewable image.

17. The display system of claim 16, wherein the display comprises a reflective display.

18. The display system of claim 10, wherein the plurality of display elements are configured to form an image by selectively modulating incident light.

19. The display system of claim 10, wherein the moveable reflective layer comprises a metal.

20. The display system of claim 10, wherein the partially reflective non-conductive layer comprises a material selected from the group consisting of:

Silicon Nitride, CrO₂, CrO₃, Cr₂O₃, Cr₂O, and CrOCN.

21. A display element comprising:

a substantially transparent conductive layer;

a dielectric layer;

a partially reflective layer, wherein the dielectric layer is positioned between the conductive layer and the partially reflective layer; and

a moveable reflective layer, the partially reflective layer being positioned between the conductive layer and the moveable reflective layer, wherein

a voltage applied between the conductive layer and the moveable reflective layer induces movement of the moveable reflective layer; and

a capacitance of the display element is reduced compared to a display element without the dielectric layer.

22. The display element of claim 21, wherein the dielectric layer has a thickness of between about 800 and 3,000 Angstroms.

23. The display element of claim 21, wherein the partially reflective layer is conductive.

24. The display element of claim 21, wherein the partially reflective layer is substantially non-conductive.

25. The display element of claim 21, further comprising another dielectric layer positioned between the partially reflective layer and the moveable reflective layer.

26. The display element of claim 21, further comprising a circuit configured to drive the moveable reflective layer such that light reflected by the moveable reflective layer and the partially reflective layer can be modulated so as to form part of a viewable image.

27. The display element of claim 26, wherein the display element comprises a display element in a reflective display.

28. The display element of claim 21, wherein the display element is included with a plurality of other display elements to form an image by selectively modulating incident light.

29. The display element of claim 21, wherein the moveable reflective layer comprises a metal.

30. The display element of claim 21, wherein the dielectric layer comprises a material selected from the group consisting of:

SiO₂, Al₂O₃, and Silicon Nitride.

31. The display element of claim 21, wherein the partially reflective layer comprises a material selected from the group consisting of:

Silicon Nitride, CrO₂, CrO₃, Cr₂O₃, Cr₂O, and CrOCN.

32. A display element comprising:

a substantially transparent conductive layer;

a dielectric layer;

a partially reflective layer, the dielectric layer being positioned between the conductive layer and the partially reflective layer; and

a moveable reflective layer, the moveable reflective layer being separated from the partially reflective layer by a gap, wherein when the display element is in an actuated state, the display element appears white to a viewer and in a released state the display element appears non-white to the viewer.

33. The display element of claim 32, wherein the gap is sized so that in the released state the display element appears at least one of black, blue, green, and red.

34. The display element of claim 32, wherein the partially reflective layer is substantially non-conductive.

35. The display element of claim 32, wherein the partially reflective layer has a thickness of between about 40 and 150 Angstroms.

36. The display element of claim 32, wherein the dielectric layer has a thickness of between about 800 and 3,000 Angstroms.

37. The display element of claim 32, wherein a distance between the partially reflective layer and the reflective layer when the display element is in the actuated state is less than about 200 Angstroms.

38. The display element of claim 37, wherein a distance between the partially reflective layer and the reflective layer when the display element is in the released state is less than about 1,550 Angstroms.

39. The display element of claim 32, further comprising an additional dielectric layer positioned between the partially reflective layer and the moveable reflective layer,

wherein a thickness of the dielectric layer is less than about 150 Angstroms.

40. The display element of claim 32, further comprising a circuit configured to drive the moveable reflective layer such that light reflected by the moveable reflective layer and the partially reflective layer can be modulated so as to form part of a viewable image.

41. The display element of claim 40, wherein the display element comprises a display element in a reflective display.

42. The display element of claim 32, wherein the display element is included with a plurality of other display elements to form an image by selectively modulating incident light.

43. The display element of claim 32, wherein the movable reflective layer comprises a metal.

44. The display element of claim 32, wherein the dielectric layer comprises a material selected from the group consisting of:

SiO₂, Al₂O₃, and Silicon Nitride.

45. The display element of claim 32, wherein the partially reflective layer comprises a material selected from the group consisting of:

Silicon Nitride, CrO₂, CrO₃, Cr₂O₃, Cr₂O, and CrOCN.