Amplification of MEMS motion

• US 6,781,744 B1
• Filed: 06/11/2003
• Issued: 08/24/2004
• Est. Priority Date: 06/11/2003
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Simon, Maria E., Pardo, Flavio, Lopez, Omar D., Aksyuk, Vladimir A.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): HASAN, MOHAMMED A
• Application Number:
  US10/459,108
• Time in Patent Office: 440 Days
• Field of Search: 359/290-292, 359/295, 359/198, 310/90, 310/309
• US Class Current: 359/290
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 3/0062 Devices moving in two or more dimensions, i.e. having special features which allow movement in more than one dimension
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 6/3518 the reflective optical element being an intrinsic part of a MEMS device, i.e. fabricated together with the MEMS device MEMS devices in general B81B; manufacture of MEM devices in general B81C; micromechanical devices controlling the direction of light G02B26/0833
• CPC Class Codes: G02B 6/357 Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841

Abstract

A MEMS device having a movable mirror and a movable actuator plate mechanically coupled together such that a relatively small displacement of the plate results in mirror rotation by a relatively large angle. In a representative embodiment, the mirror and actuator plate are supported on a substrate. The actuator plate moves in response to a voltage difference applied between the plate and an electrode located on the substrate beneath that plate. One or more springs attached to the plate provide a counteracting restoring force when they are stretched from their rest positions by the plate motion. A spring attached between the actuator plate and the mirror transfers the motion of the actuator plate to the mirror such that, when the actuator plate moves toward the substrate, the mirror moves away from the substrate. A representative MEMS device of the invention configured with a mirror that is about 100 μm in length is capable of producing the mirror rotation angle of about 15 degrees using an actuator voltage of only about 50 V.

Claims

1. A MEMS device, comprising:

first and second movable plates, each supported on and positioned offset from a substrate, wherein;

the second plate is supported by a spring attached between the second plate and a stationary post supported on the substrate;

each of the first and second plates is adapted to move with respect to the substrate, wherein the first plate is adapted to move in response to a voltage applied between an electrode and the first plate; and

the first and second plates are mechanically coupled together such that motion of the first plate with respect to the substrate produces motion of the second plate with respect to the substrate and with respect to the first plate.

2. The device of claim 1, wherein the second plate is adapted to rotate with respect to the substrate.

3. The device of claim 2, wherein:

a rotation axis of the second plate defines first and second portions of the second plate, said portions including opposite ends of the second plate with respect to the rotation axis;

the first plate is movably connected to the first portion; and

motion of the first plate toward the substrate produces motion of the second portion in a direction away from the substrate.

4. The device of claim 3, wherein length of the second portion is greater than length of the first portion.

5. The device of claim 2, wherein:

the first plate is adapted to rotate with respect to the substrate; and

rotation of the first plate by a first angle produces rotation of the second plate by a second angle whose magnitude is greater than the magnitude of the first angle.

6. The device of claim 5, wherein, when the first plate rotates in one direction, the second plate rotates in the opposite direction.

7. The device of claim 1, wherein:

a first end of the first plate is movably connected to the second plate;

a second end of the first plate is connected to the substrate;

the connection between the first plate and the substrate is a flexible connection; and

displacement of the first end of the first plate corresponds to displacement of the first plate relative to the substrate.

8. The device of claim 1, wherein:

a first end of the first plate is movably connected to the second plate;

a second end of the first plate is connected to the substrate;

the connection between the first plate and the substrate is a rigid connection; and

displacement of the first end of the first plate corresponds to bending of the first plate.

9. The device of claim 1, wherein:

the second plate has a reflective surface; and

the device is configured as an optical cross-connect.

10. The device of claim 1, wherein the device is part of an array of MEMS devices supported on the substrate.

11. A MEMS device, comprising:

first and second plates, each supported on and positioned offset from a substrate, wherein;

the second plate is rotatably connected to the substrate, wherein the rotatable connection defines a rotation axis of the second plate, the rotation axis defining first and second portions of the second plate, said portions including opposite ends of the second plate with respect to the rotation axis;

a first end of the first plate is movably connected to the first portion of the second plate;

a second end of the first plate is connected to the substrate; and

the connection between the first plate and the substrate is a flexible connection and displacement of the first end of the first plate corresponds to displacement of the first plate relative to the substrate.

12. The device of claim 11, further comprising an electrode positioned between the first plate and the substrate and electrically isolated from the first plate.

13. The device of claim 11, wherein, when the first end of the first plate is moved toward the substrate, the second plate rotates such that the second portion of the second plate moves away from the substrate.

14. The device of claim 13, wherein the magnitude of the rotation of the second plate is greater than the magnitude of an angle corresponding to the displacement of the first end of the first plate.

15. The device of claim 11, wherein the rotatable connection between the second plate and the substrate is provided by one or more torsional springs.

16. The device of claim 11, wherein the rotatable connection between the second plate and the substrate is provided by a serpentine spring.

17. The device of claim 11, wherein the movable connection between the first end of the first plate and the first portion of the second plate is provided by one or more torsional springs.

18. The device of claim 11, wherein the movable connection between the first end of the first plate and the first portion of the second plate is provided by a serpentine spring.

19. The device of claim 11, wherein:

the first plate is adapted to rotate with respect to the substrate; and

rotation of the first plate by a first angle produces rotation of the second plate by a second angle whose magnitude is greater than the magnitude of the first angle.

20. A MEMS device, comprising:

first and second plates, each supported on and positioned offset from a substrate, wherein;

the second plate is rotatably connected to the substrate, wherein the rotatable connection defines a rotation axis of the second plate, the rotation axis defining first and second portions of the second plate, said portions including opposite ends of the second plate with respect to the rotation axis;

a first end of the first plate is movably connected to the first portion of the second plate;

a second end of the first plate is connected to the substrate; and

the connection between the first plate and the substrate is a rigid connection and displacement of the first end of the first plate corresponds to bending of the first plate.