Side spring micro-mirror

• US 7,119,942 B2
• Filed: 06/30/2004
• Issued: 10/10/2006
• Est. Priority Date: 06/30/2004
• Status: Expired due to Fees

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Vancampen, Stephen D., Nathanson, Harvey C., Howell, Robert S., Storaska, Garrett A., Goodell, John B.
• Primary Examiner(s): Dang, Hung Xuan
• Assistant Examiner(s): TRA, TUYEN Q
• Application Number:
  US10/879,040
• Publication Number:
  US 20060012850A1
• Time in Patent Office: 832 Days
• Field of Search: 359/290, 359/291, 359/292, 359/214, 359/223, 359/224, 359/318, 359/320, 359/324
• US Class Current: 359/291
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A micro-electrical mechanical system (MEMS) mirror assembly including an array of micro-mirrors formed on a substrate and having springs on one side and which angularly tilt between ON and OFF states in response to an electrostatic force generated by a voltage applied to an electrode located on the substrate. At least one, but preferably two springs in the form of two thin strips of metal attach to post(s) at the side edge of the mirror and act as springs which provide a restoring force when the mirror is tilted between an OFF state which occurs when the mirror is flat relative to the substrate with no voltage applied, and in the ON state when the mirror is tilted when a voltage is applied.

Claims

1. A micro-mirror for use in a MEMS mirror array comprising:

a generally flat mirror body member including a light reflective surface and having a plurality of rectilinear side edges defining width and length dimensions of the mirror body member,

said body member being suspended above a substrate only on one width dimension side edge by a pair of equal length spring members which comprise an integral portion of said body member and which are equally spaced from the length dimension side edges and extend inwardly of said body member a distance of aprroximatelv one-half of the length dimension of the side edges and operate to provide a restoring force to the mirror body member to a substantially flat OFF state when tilted along said side edge to an ON state by an electrostatic pull down force generated by an actuation electrode located on the substrate forwardly adjacent an inner end portion of said spring members.

2. The micro-mirror according to claim 1 wherein said spring members are tapered inwardly from said one width dimension side edge.

3. The mirror element according to claim 1 wherein said body is on or about 5 μ

m×

5 μ

m along a side dimension.

4. The mirror element according to claim 3 wherein said array includes about 1024×

768 mirror elements.

5. The mirror element according to claim 4 wherein said array of mirror elements form a light reflective target of about 0.5 cm×

0.4 cm.

6. The mirror element according to claim 5 wherein said target is located in a pocket pen sized housing for use with a portable image projection system.

7. The micro-mirror according to claim 1 and additionally including a return electrode for an actuation pulse applied to an actuation electrode and located on the substrate adjacent the actuation electrode beneath said pair of spring members.

8. The micro-mirror according to claim 7 and additionally including a grounded set-down member for the mirror body located on and extending across the substrate adjacent the actuation electrode and the other width dimension side edge of the mirror body.

9. The micro-mirror according to claim 1 wherein the array is located in a portable housing.

10. The micro-mirror according to claim 9 wherein the housing comprises a pocket-pen sized housing.

11. The micro-mirror according to claim 1 and additionally including a grounded set-down member for the mirror body located on and extending across the substrate adjacent the actuation electrode and the other width dimension side edge of the mirror body.

12. A deflectable mirror element for an array of mirror elements, comprising:

a generally rectangular planar mirror body having a light reflective surface, and side edges defining a width dimension and a length dimension, and additionally including a plurality of substantially equal length and equal width finger members formed in mutually parallel relationship along one of said width dimension side edges of said body above a substrate and having a length less than one-half of a length dimension side edge; and

wherein a pair of said finger-like members are attached to a respective post adjacent said width dimension side edge, and the remaning finger-like members of said plurality of finger-like members are located on either side of said pair of finger-like members, said pair of finger-like members maintaining said mirror body in a first position substantially parallel to said substrate in an unactuated OFF state and for acting as springs so as to provide a restoring force to said mirror body back to said first position when tilted at a predetermined angle along said one width dimension side edge to a second position in an actuated ON state.

13. The mirror element according to claim 12 wherein said mirror body comprises a MEMS mirror element.

14. The mirror element according to claim 12 and additionally including an actuation electrode located on the substrate forward of the finger-like members for generating an electrostatic pull down force for tilting the mirror body to the ON position.

15. The mirror element according to claim 14 wherein said planar mirror is tilted downward toward the substrate in the ON position at an angle of about 20°

.

16. The mirror element according to claim 14 and additionally including an actuation pulse return electrode located on the substrate adjacent the actuation electrode and beneath the finger-like members.