Micromechanical element having adjustable resonant frequency

• US 20060071578A1
• Filed: 10/12/2005
• Published: 04/06/2006
• Est. Priority Date: 04/15/2003
• Status: Abandoned Application

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Drabe, Christian, Wolter, Alexander, Schenk, Harald
• Application Number:
  US11/249,060
• Publication Number:
  US 20060071578A1
• Time in Patent Office: Days
• US Class Current: 310/309
• CPC Class Codes: G01C 19/5642 using vibrating bars or beams
• 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 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: H02N 1/006 of the gap-closing type H02N1/004 takes precedence
• CPC Class Codes: H03H 2009/02511 Vertical, i.e. perpendicular to the substrate plane
• CPC Class Codes: H03H 9/02409 by application of a DC-bias voltage H03H9/02417 takes precedence
• CPC Class Codes: H03H 9/2457 Clamped-free beam resonators

Abstract

A micromechanical element described includes a vibrating system having a vibrating body and an elastic suspension by means of which the vibrating body is suspended to be able to vibrate, and an adjuster for adjusting a resonant frequency of the vibrating system by applying a voltage difference between at least one part of the vibrating body and at least one stationary electrode.

Claims

1. A micromechanical element comprising:

a vibrating system comprising;

a vibrating body; and

an elastic suspension by means of which the vibrating body is suspended to be able to vibrate; and

an adjuster for adjusting a resonant frequency of the vibrating system by applying a voltage difference between at least one part of the vibrating body and at least one stationary electrode.

2. The micromechanical element according to claim 1, wherein the stationary electrode is arranged such that it causes an electrostatic counter-force in a direction of the rest position when the vibrating body is deflected from its rest position.

3. The micromechanical element according to claim 1, wherein the stationary electrode is arranged such that it causes an electrostatic force in a direction away from the rest position when the vibrating body is deflected from its rest position.

4. The micromechanical element according to claim 1, comprising a static electrode of a first kind and a static electrode of a second kind, wherein the static electrode of the first kind is arranged such that it causes an electrostatic counter-force in the direction of the rest position when the vibrating body is deflected from its rest position, and the static electrode of the second kind is arranged such that it causes an electrostatic force in the direction away from the rest position when the vibrating body is deflected from its rest position.

5. The micromechanical element according to claim 1, further comprising:

a rib which may be cut through for optionally fixing the elastic suspension at a fixing point to limit a deformation range of the elastic suspension in which the elastic suspension deforms elastically when the vibrating body vibrates in a non-cut-through state and to increase same in a cut-through state.

6. The micromechanical element according to claim 5, comprising several ribs which may be cut through for fixing the elastic suspension at a respective fixing point in a non-cut-through state.

7. The micromechanical element according to claim 5, wherein the elastic suspension comprises a first part having a smaller cross-section and a second part having a greater cross-section.

8. The micromechanical element according to claim 1, wherein the vibrating body, the elastic suspension and the stationary electrode are formed in one layer.

9. The micromechanical element according to claim 8, wherein a frame having an anchor where the elastic suspension is fixed and a rib extending between a fixing point of the elastic suspension and the frame and being either cut through or not cut through are additionally formed in the layer.

10. The micromechanical element according to claim 8, wherein the static electrode is opposite to that part of the circumference of the vibrating body across a slot in the layer which is subject to the greatest deflection when the vibrating system vibrates.

11. The micromechanical element according to claim 1 having a first stationary electrode which is arranged such that it approaches the at least one part of the vibrating body with a deflection of the vibrating body from its rest position in a first deflection direction, and withdraws from the at least one part of the vibrating body with a deflection of the vibrating body from its rest position in a second deflection direction, and a second static electrode which is arranged such that it withdraws from the at least one part of the vibrating body with a deflection of the vibrating body from the rest position in the first deflection direction, and approaches the at least one part of the vibrating body with a deflection of the vibrating body from the rest position in the second deflection direction.

12. The micromechanical element according to claim 1, wherein a first torsion spring, a second torsion spring and the vibrating body are formed in one layer, wherein the first and the second torsion springs define a pivot axis for the vibrating body which divides the vibrating body into a first and a second part which move in different directions from the layer plane of the layer with a deflection of the vibrating body from its rest position, wherein a first and the second static electrode are arranged either below or above the vibrating body and the first static electrode is opposite to one of the two parts of the vibrating body and the second static electrode is opposite to the other one of the two parts.

13. The micromechanical element according to claim 1, wherein the elastic suspension has the effect of a torsion spring.

14. The micromechanical element according to claim 1, wherein the elastic suspension has the effect of a cantilevered bending spring.

15. The micromechanical element according to claim 1, wherein the elastic suspension is arranged to limit a vibrating movement of the vibrating body to a tilting movement around a pivot axis.

16. The micromechanical element according to claim 1, wherein the elastic suspension is arranged to limit a vibrating movement of the vibrating body to a translatory movement along a pivot axis.

17. A method for operating a micromechanical element having a vibrating system comprising a vibrating body and an elastic suspension by means of which the vibrating body is suspended to be able to vibrate, the method including the step of:

adjusting a resonant frequency of the vibrating system by applying a voltage difference between at least one part of the vibrating body and at least one stationary electrode.