Microelectrical mechanical structure (MEMS) optical modulator and optical display system

• US 20050172625A1
• Filed: 02/22/2005
• Published: 08/11/2005
• Est. Priority Date: 10/31/2000
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Sinclair, Michael J., Starkweather, Gary K.
• Granted Patent: US 6,990,811 B2
• Time in Patent Office: Days
• US Class Current: 60/527
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/353 the optical element being a shutter, baffle, beam dump or opaque element absorbers on light guide termination G02B6/243
• CPC Class Codes: G02B 6/3554 3D constellations, i.e. with switching elements and switched beams located in a volume
• CPC Class Codes: G02B 6/356 in an optical cross-connect device, e.g. routing and switching aspects of interconnecting different paths propagating different wavelengths to (re)configure the various input and output links switching polarized beams G02B6/3594; power equalizers G02B6/356 and G02B6/3594; path selecting means H04Q11/0001
• CPC Class Codes: G02B 6/3576 Temperature or heat actuation thermal forces controlling reflecting elements in general G02B26/0866; thermo-optic devices G02F1/0147
• CPC Class Codes: G02B 6/3584 constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: G02B 6/3594 Characterised by additional functional means, e.g. means for variably attenuating or branching or means for switching differently polarized beams
• CPC Class Codes: H04N 5/7408 Direct viewing projectors, e.g. an image displayed on a video CRT or LCD display being projected on a screen
• CPC Class Codes: H04N 5/7416 involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal

Abstract

A microelectrical mechanical out-of-plane thermal buckle-beam actuator is capable of providing transverse-plane movement of shutters. The actuator includes a pair of structural anchors secured to a substrate and one or more thermal buckle-beams secured at respective base ends to the anchors. Each buckle-beam extends substantially parallel to and spaced-apart from the substrate and is releasable from the substrate at points other than at the anchors. The thermal buckle-beam actuators are suitable for use in a microelectrical mechanical optical display system.

Claims

1. A microelectrical mechanical out-of-plane thermal buckle-beam actuator capable of providing transverse-plane movement of shutters, comprising:

a pair of structural anchors secured to a substrate; and

at least one thermal buckle beam secured at respective base ends to said anchors, said buckle beam extending substantially parallel to and spaced-apart from the substrate and releasable from the substrate other than at said anchors.

2. A microelectrical mechanical out-of-plane thermal buckle-beam actuator as recited in claim 1, further comprising:

a pivot frame including a frame base secured to said buckle beam at a coupling point positioned between a buckle beam midpoint and one of said anchors.

3. A microelectrical mechanical out-of-plane thermal buckle-beam actuator as recited in claim 2, wherein said pivot frame further comprises at least one pivot arm coupled to said frame base at one end and extending to a free end that is pivotable out-of-plane.

4. A microelectrical mechanical out-of-plane thermal buckle-beam actuator as recited in claim 3, wherein said pivot frame is released and free to move, other than where said frame base is secured to said coupling point.

5. A microelectrical mechanical out-of-plane thermal buckle-beam actuator as recited in claim 1, wherein said structural anchors and at least one thermal buckle beam comprise electrically semi-conductive and positive coefficient of thermal expansion properties.

6. A microelectrical mechanical out-of-plane thermal buckle-beam actuator as recited in claim 5, wherein said at least one thermal buckle beam is formed of silicon and the actuator is activatable by supplying an electrical activation current through said buckle beam, thereby causing said buckle beam to expand longitudinally due to the positive temperature coefficient of expansion of silicon and buckling away from the substrate.

7. A microelectrical mechanical out-of-plane thermal buckle-beam actuator as recited in claim 6, wherein said at least one buckle beam is formed so as to have a widened aspect ratio, with its width (parallel to the substrate) greater than its thickness (perpendicular to the substrate), thus providing a bias for buckling away from the substrate rather than parallel to it.

8. A microelectrical mechanical out-of-plane thermal buckle-beam actuator as recited in claim 7, wherein buckling of said at least one buckle beam away from said substrate in the activated state of the actuator causes a free end of said pivot frame to pivot away from the substrate.

9. A microelectrical mechanical out-of-plane thermal buckle-beam actuator as recited in claim 8, wherein said pivot frame is rotatable about said frame base, and the free end is movable so as to exert a pivoting force outward away from the substrate.

10. A microelectrical mechanical out-of-plane thermal buckle-beam actuator as recited in claim 9, wherein said at least one buckle beam cools and contracts when said electrical activation current ceases, thereby causing the free end of said pivot frame to return to its initial position.