Bistable latching actuator for optical switching applications

• US 20040223204A1
• Filed: 05/09/2003
• Published: 11/11/2004
• Est. Priority Date: 05/09/2003
• Status: Active Grant

• Current Assignee: BEI Sensors & Systems Company Incorporated (Schneider Electric SE)
• Original Assignee: OpticNet Inc.
• Inventors: Ostrom, Robert, Mao, Minyao, Lim, Martin
• Granted Patent: US 6,865,313 B2
• Time in Patent Office: Days
• US Class Current: 359/210
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G02B 6/358 Latching of the moving element, i.e. maintaining or holding the moving element in place once operation has been performed; includes a mechanically bistable system

Abstract

Bistable latching actuator for use in optical fiber switching applications having a generally planar mechanism with an arm that carries a mirror for movement in a direction perpendicular to the plane of the mechanism, and a bistable mechanical latch for retaining the mirror in stable positions on opposite sides of the plane without contacting the arm. Movement between the two stable positions is initiated and damped with an electrostatic comb drive.

Claims

1. A bistable latching actuator for use in optical fiber switching applications, comprising:

a pair of rocker arms disposed end-to-end for movement into and out of a plane, a flexible coupling between confronting ends of the arms, a mirror mounted on one of the arms, means yieldably urging the arms toward each other with a force that causes the arms to rock to and remain in two stable latching positions with the confronting ends on opposite sides of the plane, and means for selectively moving the arms between the two stable latching positions.

2. The actuator of claim 1 wherein the flexible coupling comprises a spring.

3. The actuator of claim 1 wherein the means for switching moving the arms between the two positions comprises an electrostatic comb drive for applying a force to the arms in a direction generally perpendicular to the plane.

4. The actuator of claim 1 including a sensor for monitoring the positions of the arms.

5. The actuator of claim 4 wherein the sensor comprises a comb sensor having a plurality of fingers coupled to one of the arms and forming a capacitor which varies in capacitance in accordance with the position of the arms.

6. A bistable latching actuator for use in optical fiber switching applications, comprising:

a pair of rocker arms disposed end-to-end, laterally extending cross arms affixed to the rocker arms, longitudinally extending mounting springs connected to the cross arms and supporting the rocker arms for movement relative to a plane, a coupling spring extending longitudinally between confronting ends of the rocker arms and constraining the confronting ends for movement in concert between opposite sides of the plane, a mirror carried by one of the rocker arms, means for compressing the springs to preload the springs and thereby bias the confronting ends of the rocker arms toward stable latching positions on opposite sides of the plane, and means for selectively switching the arms between the stable latching positions.

7. The actuator of claim 6 wherein the mirror is carried by a portion of the rocker arm which extends beyond the cross arm in cantilevered fashion.

8. The actuator of claim 6 wherein the means for compressing the springs includes a preloader which bears against the mounting springs supporting one of the rocker arms and is movable between longitudinally advanced and retracted positions.

9. The actuator of claim 8 wherein the preloader comprises a longitudinally extending stem, a pair of laterally extending flexures supporting the stem for movement between the advanced and retracted positions, and a cross beam which is affixed to the stem and bears against the mounting springs.

10. The actuator of claim 8 including a latch for holding the preloader in the advanced position.

11. The actuator of claim 6 wherein the means for switching the arms between the two positions comprises an electrostatic comb drive for applying a force to the arms in a direction generally perpendicular to the plane.

12. A bistable latching actuator for use in optical fiber switching applications, comprising:

a substrate, first and second rocker arms disposed end-to-end and generally parallel to a major surface of the substrate, a mirror carried by the first rocker arm for movement in a direction generally perpendicular to the surface of the substrate, cross arms extending laterally from the rocker arms and parallel to the surface of the substrate, a first set of mounting springs extending between the cross arms on the first rocker arm and anchors affixed to the substrate, a longitudinally extending stem supported by a pair of laterally extending flexures for movement between advanced and retracted positions, a cross beam affixed to the stem, a second set of mounting springs disposed between the cross beam and the cross arm on the second rocker arm, a spring which couples the confronting ends of the rocker arms together for movement in concert, a latch engagable with the stem for holding the stem in its advanced position with the springs compressed and biasing the confronting ends of the rocker arms toward stable latching positions on opposite sides of a plane parallel to the surface of the substrate, and an electrostatic comb drive having interleaved fingers affixed to the rocker arms and to the substrate for initiating movement of the rocker arms between the stable latching positions.

13. A bistable latching actuator for use in optical fiber switching applications, comprising a generally planar mechanism having an arm which carries a mirror for movement in a direction perpendicular to the plane of the mechanism, and a bistable mechanical latch for retaining the mirror in stable positions on opposite sides of the plane without contacting the arm.

14. The actuator of claim 13 wherein the stable positions are disposed symmetrically of the plane.

15. The actuator of claim 13 wherein the arm is mounted for pivotal movement into and out of the plane, and the latch includes a spring coupled to the arm in such manner that the spring is compressed when the arm is in the plane and relaxed when the mirror is in the stable positions.

16. The actuator of claim 13 including an electrostatic comb drive for applying a force to the arm to initiate and damp movement between the stable positions.

17. A bistable latching actuator for use in optical fiber switching applications, comprising a generally planar mechanism having an arm which carries a mirror for movement between two stable positions on opposite sides of the plane of the mechanism, and an electrostatic comb drive for applying a force to the arm to initiate and damp movement between the stable positions.

18. A bistable latching actuator for use in optical fiber switching applications, comprising:

a pair of longitudinally extending rocker arms disposed end-to-end, mounting springs supporting the rocker arms for rocking movement relative to a plane, a coupling spring interconnecting confronting ends of the rocker arms and constraining the confronting ends for movement in concert between opposite sides of the plane, a mirror carried by one of the rocker arms, and a preloader for exerting a preloading force upon the springs so that the springs bias the confronting ends of the rocker arms toward stable latching positions on opposite sides of the plane.

19. The actuator of claim 18 wherein the mounting springs extend in a direction generally parallel to the rocker arms and are compressed by the preloading force.

20. The actuator of claim 18 wherein the mounting springs are leaf springs which extend in a direction generally perpendicular to the rocker arms.

21. The actuator of claim 18 wherein the mounting springs are generally U-shaped and have relatively long central sections which extend in a direction generally perpendicular to the rocker arms.

22. The actuator of claim 18 wherein the confronting ends of the rocker arms are connected together by a back-to-back pair of U-shaped springs.

23. The actuator of claim 18 wherein the confronting ends of the rocker arms are connected together by springs spaced laterally apart on opposite sides of the rocker arms and positioned between laterally extending cross arms at the confronting ends of the rocker arms.

24. The actuator of claim 18 wherein the preloader comprises a longitudinally extending stem, laterally extending flexures supporting the stem for movement between longitudinally advanced and retracted positions, and a cross beam which is affixed to the stem and bears against the mounting springs supporting one of the rocker arms.

25. The actuator of claim 24 including an enlarged head toward one end of the stem and a latch engagable with the enlarged head for holding the stem in the advanced position.

26. The actuator of claim 24 including a lock stem movable between laterally advanced and retracted positions relative to the longitudinally extending stem, mating teeth carried by the stems for locking engagement with each other when the stems are in their advanced positions, and resilient means urging the lock stem toward its advanced position.

27. The actuator of claim 18 wherein the preloader comprises a longitudinally extending stem and a bistable spring system supporting the stem for movement to a stable preload position in which forces produced by the bistable spring system balance the forces produced by the mounting spring and the coupling spring.

28. The actuator of claim 27 wherein the bistable spring system comprises a pair of laterally extending leaf springs connected end-to-end in offset planes between the longitudinally extending stem and a support.

29. A bistable latching actuator for use in optical fiber switching applications, comprising:

a pair of longitudinally extending rocker arms disposed end-to-end, longitudinally compressible mounting springs supporting the rocker arms for rocking movement relative to a plane, a longitudinally compressible coupling spring interconnecting confronting ends of the rocker arms and constraining the confronting ends for movement in concert between opposite sides of the plane, a mirror carried by one of the rocker arms, a preloader movable between longitudinally advanced and retracted positions relative to the rocker arms for exerting a compressive force upon the springs in the advanced position, and a latch for holding the preloader in the advanced position.

30. A bistable latching actuator for use in optical fiber switching applications, comprising:

a substrate, first and second axially elongated rocker arms disposed end-to-end and generally parallel to a major surface of the substrate, a mirror carried by the first rocker arm, axially compressible mounting springs connected between the rocker arms and the substrate, means interconnecting the confronting ends of the rocker arms for movement in concert between stable latching positions on opposite sides of a plane parallel to the surface of the substrate, with the mirror moving in a direction generally perpendicular to the surface, and a preloader for exerting a compressive force on the springs to urge the rocker arms toward the latching positions.

31. The latching actuator of claim 30 wherein the means interconnecting the confronting ends of the rocker arms comprises an axially compressible spring.

32. The latching actuator of claim 30 wherein the mirror is mounted on an outer end portion of the arm.

33. The latching actuator of claim 30 wherein the preloader is movable between an advanced position in which the springs are compressed and a retracted position in which the springs are relaxed, and the preloader can be latched in the advanced position.