Interferometric modulation of radiation

• US 20040240032A1
• Filed: 01/05/2004
• Published: 12/02/2004
• Est. Priority Date: 05/05/1994
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Miles, Mark W.
• Granted Patent: US 7,692,844 B2
• Time in Patent Office: Days
• US Class Current: 359/291
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G02B 2006/12104 Mirror; Reflectors or the like
• 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
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: G02B 27/01 Head-up displays
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 6/12 of the integrated circuit kind electric integrated circuits H01L27/00
• CPC Class Codes: G02F 1/13725 based on guest-host interaction G02F1/13762, G02F1/13737, take precedence
• CPC Class Codes: G02F 1/169 based on orientable non-spherical particles having a common optical characteristic, e.g. suspended particles of reflective metal flakes
• CPC Class Codes: G02F 1/216 using liquid crystals, e.g. liquid crystal Fabry-Perot filters
• CPC Class Codes: G02F 2203/03 scattering
• CPC Class Codes: G06F 3/1431 using a single graphics controller
• CPC Class Codes: G06F 3/1446 display composed of modules, e.g. video walls
• CPC Class Codes: G06F 3/147 using display panels
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• CPC Class Codes: G09G 2300/0452 : Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 3/001 : using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP
• CPC Class Codes: G09G 3/2014 : by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/2074 : using sub-pixels
• CPC Class Codes: G09G 3/2077 : by a combination of two or more gradation control methods
• CPC Class Codes: G09G 3/3466 : based on interferometric effect
• CPC Class Codes: G09G 5/02 : characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H01Q 9/26 : with folded element or elements, the folded parts being spaced apart a small fraction of operating wavelength resonant loop antennas H01Q7/00

Abstract

Improvements in an interferometric modulator that cavity defined by two walls.

Claims

1. An interferometric modulator comprising a cavity defined by two walls, at least two arms connecting the two walls to permit motion of the walls relative to each other, the two arms being configured and attached to a first one of the walls in a manner that enables mechanical stress in the first wall to be relieved by motion of the first wall essentially within the plane of the first wall.

2. The modulator of claim 1 in which the motion of the first wall is rotational.

3. The modulator of claim 1 in which each of the arms has two ends, one of the ends attached to the first wall and a second end that is attached at a point that is fixed relative to a second one of the walls, the point of attachment of the second end being offset, with reference to an axis that is perpendicular to the first wall, from the end that is attached to the second wall.

4. The modulator of claim 1 in which the arms are configured to achieve a desired spring constant.

5. The modulator of claim 4 in which the lengths of the arms are configured to achieve the desired spring constant.

6. The modulator of claim 4 in which the thicknesses of the arms are configured to achieve the desired spring constant.

7. The modulator of claim 4 in which the positions along edges of the first wall where the arms are attached is selected to achieve the desired spring constant.

8. The modulator of claim 1 in which the first wall has two essentially straight edges and one end of each of the arms is attached at the middle of one of the edges.

9. The modulator of claim 1 in which the first wall has two essentially straight edges and an end of each of the arms is attached at the end of one of the edges.

10. The modulator of claim 9 comprising a third arm connecting the two walls.

11. The modulator of claim 1 comprising a third arm and a fourth arm each connecting the two walls.

12. The modulator of claim 10 or 11 in which the arms define a pinwheel configuration.

13. An array of interferometric modulators, each of the interferometric modulators comprising a cavity defined by two walls, at least two arms connecting the two walls to permit motion of the walls relative to each other, the walls and arms of different ones of the modulators being configured to achieve different spring constants associated with motion of the walls relative to each other.

14. The modulator of claim 13 in which each of the arms has two ends, one of the ends attached to the first wall and a second end that is attached at a point that is fixed relative to a second one of the walls, the point of attachment of the second end being offset, with reference to an axis that is perpendicular to the first wall, from the end that is attached to the second wall.

15. A method of fabricating an interferometric modulator comprising forming two walls of a cavity connected by at least two arms and, after the forming, permitting the a first one of the walls to rotate in the plane of the first wall relative to the arms to relieve mechanical stress in the first wall.

22. The modulator of claim 15 in which the aperture comprises a round hole in the center of the wall.

16. An interferometric modulator comprising three walls that are generally parallel to one another, the walls being supported for movement of at least one of the walls relative to the other two, and control circuitry for driving at least one of the walls to discrete positions representing three discrete states of operation of the modulator.

17. The modulator of claim 16 in which in one of the three discrete states, there is a gap between the first and a second of the two walls and a gap between the second and a third of the two walls, in a second of the three discrete states, there is a gap between the first and the second of the two walls and no gap between the second and the third of the two walls, and in the third of the three discrete states, there is no gap between the first and the second of the two walls and no gap between the second and the third of the two walls.

18. The modulator of claim 16 in which each membrane comprises a combination of dielectric, metallic, or semiconducting films.

19. An interference modulator comprising a cavity defined by two walls that are movable relative to one another to and from a contact position in which the two walls are essentially adjacent to one another, and spacers mounted to form part of one of the walls to reduce the surface area over which the two walls touch in the contact position.

20. The modulator of claim 19 in which the spacers comprise electrodes and further comprising conductors to feed current to the electrodes.

21. An interference modulator comprising a cavity defined by two walls that are separated by a fluid-filled gap, the two walls being movable relative to each other to change the volume of the gap, and an aperture in one of the walls configured to control the damping effect of fluid moving into or out of the gap as the volume of the gap changes.

23. An interference modulator comprising at least two walls that are movable relative to each other to define a cavity between them, the relative positions of the walls defining two modes, one in which the modulator reflects incident light and appears white and another in which the modulator absorbs incident light and appears black.

24. The modulator of claim 23 in which one of the walls comprises a sandwich of a dielectric between metals, and the other of the walls comprises a dielectric.

25. An interferometric modulator comprising a cavity defined by two walls, at least two arms connecting the two walls to permit motion of the walls relative to each other, with the response time of the modulator being controlled to a predetermined value by a combination of at least two of:

the lengths of the arms, the locations at which the arms are connected to the walls, the thickness of one of the walls, the thickness of the arms, the presence and dimensions of damping holes, and the ambient gas pressure in the vicinity of the modulator.

26. An interferometric modulator comprising a cavity defined by two walls, at least two arms connecting the two walls to permit motion of the walls relative to each and a charge deposition mitigating device comprising at least one of actuation rails or the application of alternating polarity drive voltages.

27. An interferometric modulator comprising a cavity defined by two walls held by a support comprising two materials such that the electrical or mechanical properties of the mechanical support differ at different locations in a cross-section of the mechanical support.

28. The modulator of claim 27 in which the support comprises a laminate of two or more discrete materials.

29. The modulator of claim 27 in which the support comprises or a gradient of two or more materials.

30. The modulator of claim 27 in which the two materials exhibit respectively different and complementary electrical, mechanical, or optical properties.

31. A method for use in fabricating a microelectromechanical structure, comprising

using a gas phase etchant to remove a deposited sacrificial layer.

32. The method of claim 31 in which the MEMS comprises an interference modulator in which a wall of the modulator is formed on the substrate and the gas phase etchant removes the sacrificial layer from between the wall and the substrate.

33. The process of claim 31 in which the gas phase etchant includes one of the following:

XeF2, BrF3, ClF3, BrF5, or IF5.

34. A method of making arrays of microelectromechanical structure on a production line comprising

forming electronic features on a surface of a glass or plastic substrate that is at least as large as 14″

×

16″

, and

micromachining electromechanical structures on the substrate.

35. The method of claim 34 in which the microelectromechanical structure comprises interference modulators.

36. The method of claim 34 in which steps of forming the electronic features are overlapping with steps of micromachining the structures.

37. The method of claim 34 in which steps of forming the electronic features are non-overlapping with steps of micromachining the structures.