Mirror Device and Mirror Device Manufacturing Method

• US 20090244676A1
• Filed: 12/27/2006
• Published: 10/01/2009
• Est. Priority Date: 01/12/2006
• Status: Active Grant

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Shimokawa, Fusao, Uchiyama, Shingo, Ishii, Hiromu, Sasakura, Kunihiko, Yamaguchi, Johji
• Granted Patent: US 7,978,388 B2
• Time in Patent Office: Days
• US Class Current: 359/225.100
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129

Abstract

When a mirror (230) rotates with a maximum angle, a distance from the rotation center of the mirror (230) to the edge of the mirror (230) along a direction horizontal to an electrode substrate (300) is larger than a distance from a perpendicular, perpendicular to the horizontal direction and extending through the rotation center, to the distal end of an electrode (340a-340d) along the horizontal direction. Even when the mirror (230) rotates to come into contact with the electrode substrate (300), since the electrode (340a-340d) does not exist at a position with which the mirror (230) comes into contact when rotating, the mirror (230) and the electrode (340a-340d) can be prevented from being electrodeposited.

Claims

1. A mirror device characterized by comprising:

a mirror rotatably supported by an upper substrate;

a first electrode which is formed on a lower substrate opposing said upper substrate to be spaced apart therefrom by a predetermined gap, and controls a tilt angle of said mirror; and

a collision preventive structure which is provided to said mirror and prevents collision of said mirror with said first electrode when said mirror rotates.

2. A mirror device according to claim 1,

characterized in that when said mirror rotates with a maximum angle, a distance from a rotation center of said mirror to an edge of said mirror along a direction horizontal to said lower substrate is larger than a distance from a perpendicular, perpendicular to the horizontal direction and extending through the rotation center, to a distal end of said first electrode along the horizontal direction.

3. A mirror device according to claim 2,

characterized in that said first electrode is disposed at a position closer to the rotation center of said mirror than a position on said lower substrate with which said mirror comes into contact when rotating.

4. A mirror device according to claim 2,

characterized by further having a second electrode which is disposed at a position farther from the rotation center of said mirror than the position on said lower substrate with which said mirror comes into contact when rotating, and controls a tilt angle of said mirror together with said first electrode.

5. A mirror device according to claim 2,

characterized in that said mirror has a first projection, projecting along a radial direction of said mirror, at an edge thereof.

6. A mirror device according to claim 5,

characterized in that said first projection has the same potential as that of said mirror.

7. A mirror device according to claim 2, characterized in that

said mirror device further comprises a gimbal which is supported to be rotatable with respect to said upper substrate, rotatably supports said mirror arranged in an inner opening thereof, and has the same potential as that of said mirror, and

when said gimbal rotates with a maximum angle, a distance from a rotation center of said gimbal to an edge of said gimbal along a direction horizontal to said lower substrate is larger than a distance from a perpendicular, perpendicular to the horizontal direction and extending through the rotation center, to a distal end of said first electrode along the horizontal direction.

8. A mirror device according to claim 7,

characterized in that said first electrode is disposed at a position closer to the rotation center of said gimbal than a position on said lower substrate with which said gimbal comes into contact when rotating.

9. A mirror device according to claim 8,

characterized in that said gimbal has a second projection, projecting along a radial direction of said gimbal, at an edge thereof.

10. A mirror device according to claim 9,

characterized in that said second projection has the same potential as that of said mirror and said gimbal.

11. A mirror device according to claim 2,

characterized by further comprising an insulating member which is disposed at a position on said lower substrate with which one of said mirror and said gimbal comes into contact when rotating.

12. A mirror device according to claim 2,

characterized by further having a conductive member which is disposed at a position on said lower substrate with which one of said mirror and said gimbal comes into contact when rotating and which has the same potential as that of said mirror and said gimbal.

13. A mirror device according to claim 1,

characterized in that said upper substrate comprises an SOI substrate comprising a silicon base portion having a mirror formation region, a buried insulating layer formed on said base portion, and a silicon layer formed on said buried insulating layer, and includes

a base formed in said mirror formation region and a mirror rotatably connected to said base through a pair of connectors, and

a projecting structure formed on said mirror in said silicon layer.

14. A mirror device according to claim 13,

characterized in that said projecting structure is arranged at a center of said mirror.

15. A mirror device according to claim 13,

characterized in that said projecting structure is arranged on a periphery of said mirror.

16. A mirror device according to claim 15,

characterized in that a plurality of projecting structures are arranged around said mirror.

17. A mirror device according to claim 13,

characterized by further comprising an insulating portion formed on said projecting structure.

18. A method of manufacturing a mirror device having a mirror rotatably supported with respect to an upper substrate, and a first electrode which is formed on a lower substrate opposing the upper substrate and controls a tilt angle of the mirror, characterized by comprising at least the steps of:

forming a projecting structure on a surface of a mirror formation region of a silicon layer of an SOI substrate comprising a substrate portion, a buried insulating layer on the substrate portion, and the silicon layer on said buried insulating layer;

forming a movable portion formation mask pattern on a surface of the silicon layer, processing the silicon layer by etching using the movable portion formation mask pattern as a mask, and forming a base and plate-like mirror, connected to the base through a pair of connectors, on the mirror formation region on the buried insulating layer;

forming a frame formation mask pattern, with an opening serving as a mirror formation region, on a surface of the substrate portion, removing the substrate portion and the buried insulating layer by etching using the frame formation mask pattern as a mask, to expose the silicon layer on a substrate portion side in the mirror formation region, and forming a frame portion outside the mirror formation region; and

forming a reflecting film on a surface of the mirror, which is opposite to a surface where the projecting structure is formed, of the upper substrate where the projecting structure, the mirror and the frame portion are formed.

19. A mirror device manufacturing method according to claim 18,

characterized in that the projecting structure is arranged at a center of the mirror.

20. A mirror device manufacturing method according to claim 18,

characterized in that the projecting structure is arranged on a periphery of the mirror structure.