Electrostatic microactuator with offset and/or inclined comb drive fingers

• US 6,384,510 B1
• Filed: 04/12/2000
• Issued: 05/07/2002
• Est. Priority Date: 12/15/1998
• Status: Expired due to Term

• Current Assignee: Coherent Inc (Coherent Corp.)
• Original Assignee: iolon, Inc. (Coherent Corp.)
• Inventors: Jerman, John H., Grade, John D.
• Primary Examiner(s): Ramirez, Nestor
• Assistant Examiner(s): LE, DANG D
• Application Number:
  US09/547,698
• Time in Patent Office: 755 Days
• Field of Search: 310/309, 310/308, 310/40.MM, 360/294.5, 360/294.2, 361/283.3
• US Class Current: 310/309
• CPC Class Codes: G02B 6/3514 the reflective optical element moving along a line so as to translate into and out of the beam path, i.e. across the beam path
• CPC Class Codes: G02B 6/3548 1xN switch, i.e. one input and a selectable single output of N possible outputs
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• 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: G11B 11/10563 Access of indexed parts
• CPC Class Codes: G11B 7/08564 using galvanomirrors
• CPC Class Codes: H02N 1/008 Laterally driven motors, e.g. of the comb-drive type

Abstract

An electrostatic microactuator comprising a substrate and at least one comb drive assembly having a first comb member mounted on the substrate and a second comb member overlying the substrate. The first comb member has a plurality of first comb fingers. The second comb member has a plurality of second comb fingers. The second comb member is movable between a first position in which each second comb finger is not substantially fully interdigitated with an adjacent pair of first comb fingers and a second position in which each such second comb finger is substantially fully interdigitated with such adjacent pair of first comb fingers. Each of the second comb fingers is offset relative to the midpoint between the adjacent pair of first comb fingers when in the first position and is substantially centered on such midpoint when in the second position.

Claims

1. An electrostatic microactuator comprising a substrate, at least one comb drive assembly having first and second comb drive members, the first comb drive member being mounted on the substrate and the second comb dive member overlying the substrate, at least one spring member having a first end portion coupled to the substrate and a second end portion coupled to the second comb drive member, the first comb drive member having a first elongate member and a plurality of spaced-apart first comb drive fingers extending from a side of the first elongate member with respective spaces therebetween, the second comb drive member having a second elongate member and a plurality of spaced-apart second comb drive fingers extending from a side of the second elongate member, the first comb drive member having a midpoint in the space between each adjacent pair of the first comb drive fingers, the second comb drive member being movable between a first position in which each second comb drive finger is not substantially fully interdigitated with an adjacent pair of first comb drive fingers and a second position in which each such second comb drive finger is substantially fully interdigitated with such adjacent pair of first comb drive fingers, each of the second comb drive fingers being offset relative to the second elongate member from the midpoint between the adjacent pair of first comb drive fingers when in the first position and being substantially centered on such midpoint when in the second position.

2. A microactuator as in claim 1 wherein the at least one spring member comprises first and second beam-like spring members, the at least one comb drive assembly being disposed between the first and second beam-like spring members.

3. A microactuator as in claim 1 wherein the at least one comb drive assembly has first and second extremities and wherein the at least one spring member is a single beam-like member having a first end portion coupled to the substrate in the vicinity of the first extremity of the at least one comb drive assembly and a second end portion coupled to the second comb drive member in the vicinity of the second extremity of the at least one comb dive assembly.

4. A microactuator as in claim 3 wherein the at least one comb drive assembly comprises first and second comb drive assemblies, each of the first and second comb drive assemblies having such first and second comb drive members.

5. A microactuator as in claim 1 wherein the first elongate member is substantially parallel to the second elongate member.

6. A microactuator as in claim 1 wherein the second comb drive member moves to the second position in a direction substantially perpendicular to the second elongate member.

7. A microactuator as in claim 1 wherein each of the second comb drive fingers is joined to the second elongate member at a second oblique angle.

8. A microactuator as in claim 7 wherein each of the first comb drive fingers is joined to the first elongate member at a first oblique angle.

9. A microactuator as in claim 8 wherein the at least one comb drive assembly has first and second extremities and wherein the second oblique angle is inclined towards the first extremity of the at least one comb drive assembly and the first oblique angle is inclined towards the second extremity of the at least one comb drive assembly.

10. A microactuator as in claim 9 wherein the first and second oblique angles are equal.

11. A microactuator as in claim 10 wherein the first and second oblique angles are each approximately three degrees.

12. A microactuator as in claim 1 wherein each of the first and second comb drive fingers has a length and a constant width along the length.

13. An electrostatic microactuator comprising a substrate, at least one comb drive assembly having first-and second comb drive members, the first comb drive member being mounted on the substrate and the second comb drive member overlying the substrate, at least one spring member having a first end portion coupled to the substrate and a second end portion coupled to the second comb drive member, the first comb drive member having a first elongate member and a plurality of spaced-apart first comb drive fingers extending from a side of the first elongate member and facing the second comb drive member, the second comb drive member having a second elongate member and a plurality of spaced-apart second comb drive fingers extending from a side of the second elongate member and facing the first comb drive member, each of the second comb drive fingers being joined to the second elongate member at an oblique angle, the second comb drive member being movable between a first position in which the second comb drive fingers are not substantially fully interdigitated with the first comb drive fingers and a second position in which the second comb drive fingers are substantially fully interdigitated with the first comb drive fingers.

14. A microactuator as in claim 13 wherein each of the first comb drive fingers is joined to the first elongate member at the oblique angle.

15. A microactuator as in claim 13 wherein the at least one spring member comprises first and second beam-like spring members, the at least one comb drive assembly being disposed between the first and second beam-like spring members.

16. A microactuator as in claim 13 wherein the at least one comb drive assembly has first and second extremities and wherein the at least one spring member is a single beam-like member having a first end portion coupled to the substrate in the vicinity of the first extremity of the at least one comb drive assembly and a second end portion coupled to the second comb drive member in the vicinity of the second extremity of the at least one comb drive assembly.

17. An electrostatic microactuator comprising a substrate, at least one comb drive assembly having first and second extremities and first and second comb drive members, the first comb drive member being mounted on the substrate and the second comb drive member overlying the substrate, first and second beam-like spring members, the at least one comb drive assembly being disposed between the first and second beam-like spring members, each of the first and second beam-like spring members having a first end portion coupled to the substrate in the vicinity of he first extremity of the at least one comb drive assembly and a second end portion coupled to the second comb drive member in the vicinity of the second extremity of the at least one comb drive assembly, the first comb drive member having a first elongate member and a plurality of spaced-apart first comb drive fingers extending from a side of the first elongate member and joined to the first elongate member at a first oblique angle, the second comb drive member having a second elongate member and having a plurality of spaced-apart second comb drive fingers extending from a side of the second elongate member and joined to the first elongate member at a second oblique angle, the first comb drive fingers having respective spaces therebetween and the first comb drive member having a midpoint in the space between each adjacent pair of the first comb drive fingers, the second comb drive member being movable between a first position in which each second comb drive finger is not substantially fully interdigitated with an adjacent pair of first comb drive fingers and a second position in which each such second comb drive finger is substantially fully interdigitated with such adjacent pair of first comb drive fingers, each of the second comb drive fingers being offset relative to the second elongate member from the midpoint between the adjacent pair of first comb drive fingers when in the first position and being substantially centered on such midpoint when in the second position.

18. A microactuator as in claim 17 wherein the first and second oblique angles are equal.

19. A microactuator as in claim 17 wherein the first elongate member is substantially parallel to the second elongate member.

20. A microactuator as in claim 17 wherein the at least one comb drive assembly has a length and wherein each of the first and second beam-like spring members has a length approximating the length of the at least one comb drive assembly.

21. A linear electrostatic microactuator comprising a substrate, at least one comb drive assembly having first and second extremities and first and second comb drive members, the first comb drive member being mounted on the substrate and the second comb drive member overlying the substrate, first and second nonfolded bean-like spring members, the at least one comb drive assembly being disposed between the first and second spring members, each of the first and second spring members having a first end portion coupled to the substrate in the vicinity of the first extremity of the at least one comb drive assembly and a second end portion coupled to the second comb drive member in the vicinity of the second extremity of the at least one comb drive assembly, each of the first and second comb drive members being provided with comb drive fingers, the second comb drive member being movable between a first position in which the comb drive fingers of the first ad second comb drive members are not substantially fully interdigitated and a second position in which the comb drive fingers of the first and second comb drive members are substantially fully interdigitated.

22. A microactuator as in claim 21 wherein each of the first and second comb drive members has an elongate member, the respective comb drive fingers being longitudinally spaced apart along the elongate member and joined to the elongate member at an oblique angle.

23. A microactuator as in claim 22 wherein the first comb drive member has a midpoint in the space between each adjacent pair of the comb drive fingers, each of the comb drive fingers of the second comb drive member being offset relative to the elongate member of the second comb drive member from the midpoint between the adjacent pair of comb drive fingers of the first comb drive member when in the first position and being substantially centered on such midpoint when in the second position.

24. An electrostatic microactuator comprising a stationary comb drive member having a first elongate member and a plurality of spaced-apart first comb drive fingers extending from the first elongate member with respective spaces therebetween, the stationary comb drive member having an imaginary centerline extending in the space between each adjacent pair of first comb drive fingers, a movable comb drive member having a second elongate member and a plurality of spaced-apart second comb drive fingers extending from the second elongate member, the movable comb drive member being movable from a rest position to an actuated position in which the second comb drive fingers mesh with the first comb drive fingers, the second comb drive fingers being offset from the imaginary centerline when in the rest position and being substantially coincident with the imaginary centerline when in the actuated position.

25. A microactuator as in claim 24 fiber comprising at least one spring member coupled to the movable comb drive member for urging the movable comb drive member towards the rest position.

26. A microactuator as in claim 25 further comprising a voltage source coupled to the stationary and movable comb drive members for applying a voltage potential between the stationary and movable comb drive members to drive the movable comb drive member from the rest position to the actuated position.

27. A microactuator as in claim 24 wherein the first comb drive fingers extend from the first elongate member at a first oblique angle and the second comb drive fingers extend from the second elongate member at a second oblique angle.

28. A microactuator as in claim 27 wherein the first and second oblique angles are equal.

29. An electrostatic microactuator comprising a substrate, a first comb drive member mounted on the substrate and having a plurality of spaced-apart first comb drive fingers with respective spaces therebetween, the first comb drive member having an imaginary centerline extending in the space between each adjacent pair of first comb drive fingers, a second comb drive member overlying the substrate and having a plurality of spaced-apart second comb drive fingers, the second comb drive member being movable from a rest position to an actuated position in which the second comb drive fingers substantially interdigitate with the first comb drive fingers, the second comb drive fingers being offset from the imaginary centerline when in the rest position and being substantially coincident with the imaginary centerline when in the actuated position.

30. A microactuator as in claim 29 further comprising at least one spring member coupled to the second comb drive member for urging the second comb drive member towards the rest position.

31. A microactuator as in claim 29 further comprising a voltage source coupled to the first and second comb drive members for applying a voltage potential between the first and second comb drive members to drive the second comb drive member from the rest position to the actuated position.

32. An electrostatic microdevice comprising a substrate, a stationary comb drive member mounted on the substrate and having a first elongate member and a plurality of spaced-apart first comb drive fingers extending from the first elongate member with respective spaces therebetween, the stationary comb drive member having an imaginary centerline extending in the space between each adjacent pair of first comb drive fingers, a movable comb drive member overlying the substrate and having a second elongate member and a plurality of spaced-apart second comb drive fingers extending from the second elongate member, the second comb drive fingers being offset from the imaginary centerline when in a rest position relative to the first comb drive fingers.

33. A microdevice as in claim 32 wherein the first comb drive fingers extend from the first elongate member at a first oblique angle and the second comb drive fingers extend from the second elongate member at a second oblique angle.

34. A microdevice as in claim 33 wherein the first and second oblique angles are equal.

35. An electrostatic microdevice comprising a substrate, a first comb drive member mounted on the substrate and having a plurality of spaced-apart first comb drive fingers, a second comb drive member overlying the substrate and having a plurality of spaced-apart second comb drive fingers, the second comb drive member being movable from a first position to a second position in which each second comb drive finger substantially interdigitates with an adjacent pair of first comb drive fingers, each second comb drive finger being off centered relative to the adjacent pair of first comb drive fingers when in the first position and being centered with the adjacent pair of first comb drive fingers when in the second position.

36. A microdevice as in claim 35 further comprising at least one spring member coupled to the second comb drive member for supporting the second comb drive member over the substrate.

37. A microdevice as in claim 35 further comprising a voltage source coupled to the first and second comb drive members for applying a voltage potential between the first and second comb drive members to drive the second comb drive member from the first position to the second position.

38. An electrostatic microdevice comprising a substrate, a stationary comb drive member mounted on the substrate, the stationary comb drive member having a first elongate member and a plurality of spaced-apart first comb drive fingers extending from the first elongate member at a first oblique angle, a movable comb drive member overlying the substrate, the movable comb drive member having a second elongate member and a plurality of spaced-apart second comb drive fingers extending from the second elongate member at a second oblique angle, the movable comb drive member being movable from a first position to a second position in which the second comb drive fingers substantially interdigitate with the first comb drive fingers.

39. A microdevice as in claim 38 wherein the first and second oblique angles are equal.

40. A microdevice as in claim 38 further comprising a voltage source coupled to the stationary and movable comb drive members for applying a voltage potential between the stationary and movable comb drive members to drive the movable comb drive member from the first position to the second position.