Multilayered oscillating device with spine support

• US 6,956,684 B2
• Filed: 10/09/2003
• Issued: 10/18/2005
• Est. Priority Date: 11/08/2002
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Orcutt, John W.
• Primary Examiner(s): Phan, James
• Application Number:
  US10/681,934
• Publication Number:
  US 20050185239A1
• Time in Patent Office: 740 Days
• Field of Search: 359/198, 359/199, 359221-226, 359212-214, 310/36, 310/40.R, 310/46, 310/40.MM, 310/152, 335/229, 335/302
• US Class Current: 359/199.1
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 3/007 For controlling stiffness, e.g. ribs
• 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 26/105 with one or more pivoting mirrors or galvano-mirrors G02B26/101 takes precedence

Abstract

A multilayered torsional hinged device such as a scanning mirror including a hinge layer with an attaching member pivotally supported by torsional hinges. A front layer is bonded to the front side of the attaching member and a back layer is bonded to the back side of the attaching member. The front layer and the back layer have equal mass moments to balance the moment of inertia and stresses on the torsional hinges. Further, the attaching member and a back portion of the front layer define a spine structure that extends to the tips of the mirror. The spine structure allows reduction of weight and mass of the mirror while maintaining mirror stiffness. The back layer may be a permanent magnet if the mirror oscillating drive is a magnetic drive. Alternately, the back layer may be another silicon slice.

Claims

1. A multilayered torsional hinged resonant pivoting device comprising:

a hinge layer defining a support structure and an attaching member, said support structure for pivotally supporting said attaching member along a first axis of rotation by a pair of torsional hinges, said attaching member having a front side and a back side, and said attaching member defining spines extending in opposite directions and away from said first axis;

a front layer having a front portion, a back portion and a selected thickness, said back portion of said front layer mounted to said front side of said attaching member and said front layer having a known mass moment about said first axis; and

a back layer mounted on said back side of said attaching member and having a mass moment substantially equal to and opposite said known mass moment of said front layer, such that the center of mass of the combined front and back layers is substantially coplanar with the first axis of rotation and the moment of inertia of said multilayered torsional hinged device is substantially centered on said first axis of rotation.

2. The multilayered device of claim 1 wherein said front portion of said front layer has a first size and shape and said back portion of said front layer further defines spines corresponding to said spines defined by said attaching member.

3. The multilayered device of claim 2 wherein said back layer further defines spines corresponding to said spines defined by said attaching member.

4. The multilayered device of claim 1 wherein said back layer further defines spines corresponding to said spines defined by said attaching member.

5. The multilayered device of claim 1 wherein said hinge layer comprises an anchor member connected to said attaching member along said first axis by said first pair of torsional hinges.

6. The multilayered device of claim 5 wherein said anchor member is a support frame.

7. The multilayered device of claim 5 wherein said anchor member is a pair of anchor pads.

8. The multilayered device of claim 1 wherein said support structure of said hinge layer comprises a gimbals portion connected to said attaching member along said first axis by said pair of torsional hinges and an anchor member pivotally supporting said gimbals portion by a second pair of torsional hinges along a second axis substantially orthogonal to said first axis.

9. The multilayered device of claim 3 wherein said support structure of said hinge layer comprises a gimbals portion connected to said attaching member along said first axis by said pair of torsional hinges and an anchor member pivotally supporting said gimbals portion by a second pair of torsional hinges along a second axis substantially orthogonal to said first axis.

10. The multilayered device of claim 8 wherein said anchor member is a support frame.

11. The multilayered device of claim 1 wherein said back layer is a permanent magnet.

12. The multilayered device of claim 2 wherein said back layer is a permanent magnet.

13. The multilayered device of claim 11 and further comprising a magnetic coil connected to an alternating voltage having a frequency substantially equal to the resonant frequency of the pivoting device and wherein said magnetic coil and said permanent magnet interact to create pivotal movement of said device at said resonant frequency.

14. The multilayered device of claim 12 and further comprising a magnetic coil connected to an alternating voltage having a frequency substantially equal to the resonant frequency of the pivoting device and wherein said magnetic coil and said permanent magnet interact to create pivotal movement of said device at said resonant frequency.

15. The multilayered device of claim 2 wherein said front portion of said front layer is a reflective surface and said multilayered device is a scanning mirror.

16. The multilayered device of claim 15 wherein said back layer further defines spines corresponding to said spines defined by said attaching member.

17. The multilayered device of claim 15 wherein said back layer is a permanent magnet.

18. The multilayered device of claim 17 wherein said support structure of said hinge layer comprises a gimbals portion connected to said attaching member along said first axis by said pair of torsional hinges and an anchor member pivotally supporting said gimbals portion by a second pair of torsional hinges along a second axis substantially orthogonal to said first axis.

19. The multilayered device of claim 18 and further comprising a magnetic coil connected to an alternating voltage having a frequency equal to a selected sweep frequency of said scanning mirror and wherein said magnetic coil and said permanent magnet interact to create pivotal oscillations of said scanning mirror at said selected sweep frequency.

20. The multilayered device of claim 19 wherein said selected sweep frequency is substantially equal to the resonant pivoting frequency.

21. The multilayered device of claim 17 and further comprising a magnetic coil connected to an alternating voltage having a frequency equal to a selected sweep frequency of said scanning mirror and wherein said magnetic coil and said permanent magnet interact to create pivotal oscillations of said scanning mirror at said selected sweep frequency.

22. The multilayered device of claim 21 wherein said selected sweep frequency is substantially equal, to the resonant pivoting frequency.

23. The multilayered device of claim 3 and further comprising piezoelectric material bonded to said support structure of said hinge layer to create resonant pivoting of said mirror.

24. The multilayered device of claim 1 wherein said hinge layer is made from single crystal silicon.

25. The multilayered device of claim 2 wherein said hinge layer is made from single crystal silicon.

26. The multilayered device of claim 3 wherein said hinge layer is made from single crystal silicon.

27. The multilayered device of claim 24 wherein said front layer is made from single crystal silicon.

28. The multilayered device of claim 25 wherein said front layer is made from single crystal silicon.

29. The multilayered device of claim 26 wherein said front layer is made from single crystal silicon.

30. The multilayered device of claim 17 and further comprising a magnetic coil connected to an alternating voltage having a frequency equal to a selected sweep frequency of said scanning mirror and wherein said magnetic coil and said permanent magnet interact to create pivotal oscillations of said scanning mirror at said selected sweep frequency.

31. The multilayered device of claim 30 wherein said selected sweep frequency is substantially equal to the resonant pivoting frequency.