Micromechanical rpm sensor

• US 6,490,923 B1
• Filed: 12/14/2000
• Issued: 12/10/2002
• Est. Priority Date: 06/25/1998
• Status: Expired due to Fees

• Current Assignee: Litec-LP GmbH
• Original Assignee: Litec-LP GmbH
• Inventors: Hafen, Martin, Breng, Uwe, Handrich, Eberhard, Ryrko, Bruno
• Primary Examiner(s): MOLLER, RICHARD ALAN
• Application Number:
  US09/719,698
• Time in Patent Office: 726 Days
• Field of Search: 735/041.2, 735/040.2
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5656 the devices involving a micromechanical structure

Abstract

A micromechanical rotation rate sensor based on the Coriolis principle includes two plate-like oscillators arranged one above the other in two planes for excitation to oscillate by means of an electrostatic drive. Three elements in each case form an oscillator structure. The oscillators are in each case suspended on opposite side edges by at least one web between an associated plate-like support and an associated drive plate element. The two supports and the two drive plate elements are, in each case, arranged one above the other in layers. A fixed plate element is located between the two drive plate elements so that, in each case, an identical narrow drive gap is defined between the drive plate elements. The drive gap is considerably smaller than the distance between the plate-like oscillators. An intermediate support that fills the intermediate space is inserted between the two plate-like supports and is completely electrically isolated from the surrounding frame to further reduce the respective capacitances to be recharged. The invention reduces the electrodynamic coupling between the drive and the read-out by a factor of about 100 in comparison with known micromechanical rotation rate sensors of like design.

Claims

1. A micromechanical rotation rate sensor based on the Coriolis principle comprising, in combination:

a) two plate-like oscillators arranged one above the other in two planes for excitation via an electrostatic drive to oscillate at right angles to said planes;

b) said oscillators being suspended in the direction of a rotation axis on opposite side edges via, in each case, at least one narrow spring web between an associated plate-like support lying in the same plane via which signals are read out, and an associated drive plate element of the electrostatic drive also lying in the same plane;

c) said two supports and said two drive plate elements in each case being spaced apart, one above the other, with a fixed plate element inserted therebetween in such a manner that a narrow drive gap to the two drive plate elements is defined in each case; and

d) said drive gap is considerably smaller than the distance between said oscillators.

2. A micromechanical rotation rate sensor as defined in claim 1, further including an intermediate support which fills an intermediate space, inserted between said two plate-like supports.

3. A micromechanical rotation rate sensor as defined in claim 1 or 2 wherein said pair of drive plate elements and said pair of plate-like supports each have identical surface areas.

4. A micromechanical rotation rate sensor as defined in claim 1 characterized in that:

a) an oscillator with associated support and drive plate element is held within a surrounding frame by said spring webs; and

b) an entire structure in each case is produced from a wafer.

5. A micromechanical rotation rate sensor as defined in claim 4, additionally comprising:

a) a three-layer wafer layer composite;

b) an upper and a lower layer structure in each case surrounded by an identical frame, a support, an oscillator, and a drive plate element;

c) said fixed plate element being positioned between said to drive plate elements and connected to an identical frame; and

d) an intermediate support fills said space between said supports but is not mechanically connected to said frame formed in said third interposed layer structure within said identical frame.

6. A micromechanical rotation rate sensor as defined in claim 5, further characterized in that:

a) said intermediate support ends flush with said two supports in the direction of said two supports so that no overlapping area exists; and

b) projecting oscillators lie one above the other.

7. A micromechanical rotation rate sensor as defined in claim 1, further characterized in that said supports are connected to associated frames via torsion springs.

8. A micromechanical rotation rate sensor as defined in claim 1 wherein said drive plate elements are connected to said associated frames by spiral springs.

9. A micromechanical rotation rate sensor as defined in claim 7 or 8 wherein said oscillators are in each case connected via spring webs to said associated support on one side and to said associated plate drive element on the other side.

10. A micromechanical rotation rate sensor as defined in claim 7 wherein said torsion springs comprise cross spring joints.