Tiltable electrostatic microactuator and method for using same

• US 6,333,584 B1
• Filed: 01/05/2001
• Issued: 12/25/2001
• Est. Priority Date: 01/05/2000
• 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): Waks, Joseph
• Application Number:
  US09/755,743
• Time in Patent Office: 354 Days
• Field of Search: 310/309, 310/40.M
• US Class Current: 310/309
• CPC Class Codes: H02N 1/008 Laterally driven motors, e.g. of the comb-drive type

Abstract

A tiltable electrostatic microactuator comprising a substantially planar substrate and a rotatable member overlying the substrate for rotation about an axis of rotation extending perpendicular to the planar substrate. A plurality of comb drive assemblies are provided and each has a first comb drive member mounted on the substrate and a second comb drive member coupled to the rotatable member. Each of the first and second comb drive members is provided with comb drive fingers. First and second spaced-apart springs are included in the microactuator and each has a first end portion coupled to the substrate and a second end portion coupled to at least one of the second comb drive members for suspending the second comb drive members and the rotatable member over the substrate. The second comb drive members are movable in a direction of travel about the axis of rotation between a first position in which the comb drive fingers of the first and 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. A controller is electrically coupled to the second comb drive members and the substrate for tilting the rotatable member relative to the substrate about a pivot axis extending parallel to the planar substrate. A method for using the microactuator is provided.

Claims

1. A tiltable electrostatic microactuator comprising a substantially planar substrate, a rotatable member overlying the substrate for rotation about an axis of rotation extending perpendicular to the planar substrate, a plurality of comb drive assemblies, each of the comb drive assemblies having a first comb drive member mounted on the substrate and a second comb drive member, means for coupling the rotatable member to the second comb drive members, each of the first and second comb drive members being provided with comb drive fingers, first and second spaced-apart springs, each of the first and second springs having a first end portion coupled to the substrate and a second end portion coupled to at least one of the second comb drive members for suspending the second comb drive members and the rotatable member over the substrate, the second comb drive members being movable in a direction of travel about the axis of rotation between a first position in which the comb drive fingers of the first and 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, and a controller electrically coupled to the second comb drive members and the substrate for electrostatically tilting the rotatable member relative to the substrate about a pivot axis extending parallel to the planar substrate.

2. A microactuator as in claim 1 wherein the pivot axis extends perpendicular to the axis of rotation.

3. A microactuator as in claim 1 wherein the plurality of comb drive assemblies subtend an angle of approximately 180°

or less about the axis of rotation so as to have a fan-like shape.

4. A microactuator as in claim 3 wherein the plurality of comb drive assemblies form a semicircle having a base extending substantially along a diameter of the semicircle, the axis of rotation being disposed adjacent the base at the center of the semicircle.

5. A microactuator as in claim 1 wherein the means for coupling the rotatable member to the second comb drive members includes means for rigidly coupling the rotatable member to the second comb drive members so that the second comb drive members tilt about the pivot axis in unison with the rotatable member.

6. A microactuator as in claim 1 wherein the means for coupling the rotatable member to the second comb drive members includes means for flexibly coupling the rotatable member to the second comb drive members so that the rotatable member tilts about the pivot axis relative the substrate and the second comb drive members.

7. A microactuator as in claim 6 wherein the means for flexibly coupling the rotatable member to the second comb drive members includes first and second torsional members, each of the torsional members having a first end portion coupled to the second comb drive members and a second end portion coupled to the rotatable member.

8. A microactuator as in claim 7 wherein the first and second torsional members are collinear and extend parallel to the planar substrate.

9. A microactuator as in claim 6 wherein the second comb drive members extend radially from the axis of rotation in a first direction and the rotatable member extends radially from the axis of rotation in a second direction opposite to the first direction.

10. A microactuator as in claim 1 wherein each of the first and second springs extends substantially radially from the axis of rotation and wherein the plurality of comb drive assemblies include first and second comb drive assemblies disposed between the first and second springs.

11. A method for operating an electrostatic microactuator having a substantially planar substrate and a rotatable member and a plurality of comb drive assemblies, the rotatable member overlying the substrate for rotation about an axis of rotation extending perpendicular to the planar substrate, each of the comb drive assemblies having a first comb drive member mounted on the substrate and a second comb drive member coupled the rotatable member, each of the first and second comb drive members being provided with comb drive fingers, the second comb drive members and the rotatable member being suspended over the substrate by first and second spaced-apart springs and being movable in a direction of travel about the axis of rotation between a first position in which the comb drive fingers of the first and 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, the method comprising the steps of tilting the rotatable member relative to the substrate about a pivot axis extending parallel to the planar substrate.

12. The method of claim 11 wherein the tilting step includes the step of tilting the second comb drive members relative to the substrate about the pivot axis.

13. The method of claim 11 wherein the tilting step includes the step of tilting the rotatable member relative to the second comb drive members about the pivot axis.

14. The method of claim 11 wherein the tilting step includes the step of electrostatically tilting the rotatable member relative to the substrate.

15. The method of claim 14 wherein the tilting step includes the step of applying a voltage differential between the rotatable member and the substrate.