MEMS device with improved spring system

• US 9,097,524 B2
• Filed: 01/30/2012
• Issued: 08/04/2015
• Est. Priority Date: 09/11/2009
• Status: Active Grant

• Current Assignee: Invensense Incorporated (TDK Corporation)
• Original Assignee: Invensense Incorporated (TDK Corporation)
• Inventors: Seeger, Joseph, Anac, Ozan
• Primary Examiner(s): Martin, Laura
• Assistant Examiner(s): Shah, Samir M
• Application Number:
  US13/361,261
• Publication Number:
  US 20120125101A1
• Time in Patent Office: 1,282 Days
• Field of Search: 735/040.2, 735/041.2, 735/041.4, 735/10, 735/143.8
• US Class Current: 1/1
• CPC Class Codes: G01C 19/5733 Structural details or topology
• CPC Class Codes: G01C 19/5755 the devices having a single sensing mass

Abstract

A system and method in accordance with an embodiment reduces the cross-axis sensitivity of a gyroscope. This is achieved by building a gyroscope using a mechanical transducer that comprises a spring system that is less sensitive to fabrication imperfection and optimized to minimize the response to the rotations other than the intended input rotation axis. The longitudinal axes of the first and second flexible elements are parallel to each other and parallel to the first direction.

Claims

1. A gyroscope that detects angular velocity comprising:

a first structure including a first proof mass wherein the first proof mass oscillates in a driving direction, wherein a Coriolis force acts on the first proof mass in a sensing direction that is orthogonal to the driving direction when the gyroscope is rotated with an angular velocity about an input axis orthogonal to the driving and sensing directions;

a spring system compliant in a first direction of motion, coupled to the first structure, the spring system comprising a first flexible element;

a rigid element coupled to the first flexible element; and

a second flexible element coupled to the rigid element, wherein the first flexible element and the second flexible element, each has a longitudinal axis parallel to the first direction of motion, wherein the first structure and spring system are disposed substantially in a plane;

wherein when a force is applied to the spring system, the first and second flexible elements deflect and the rigid element rotates; and

a transducer responsive to the Coriolis force acting on the first proof mass.

2. The gyroscope of claim 1 wherein the transducer comprises capacitive sensors.

3. The gyroscope of claim 1 wherein the spring system deflects when the first proof mass oscillates.

4. The gyroscope of claim 3 wherein the driving direction is parallel to the first direction of motion.

5. The gyroscope of claim 1 wherein the first flexible element and the second flexible element each has a midpoint aligned along an axis perpendicular to the first direction of motion.

6. The gyroscope of claim 1 wherein the first flexible element and the second flexible element are both coupled to the rigid element on a first side of the rigid element.

7. The gyroscope of claim 1 wherein the first flexible element is coupled to the rigid element on a first side of the rigid element and the second flexible element is coupled to the rigid element on an opposite side of the rigid element.

8. The gyroscope of claim 1 wherein the second flexible element is anchored.

9. The gyroscope of claim 1 further comprising a third flexible element, wherein the first flexible element, the second flexible element, and the third flexible element are coupled to the rigid element.

10. The gyroscope of claim 9 further comprising a second structure including a second proof mass;

the first flexible element is coupled to the first structure and the third flexible element is coupled to the second structure, wherein the first and second proof masses move in opposite directions, wherein the spring system deflects when the first and second proof masses oscillate.

11. The gyroscope of claim 1 wherein the spring system is coupled to the first proof mass;

wherein the Coriolis force acts on the first proof mass in the sensing direction parallel to the first direction of motion; and

the first proof mass moves and the spring system deflects in response to angular velocity about the input axis.

12. The gyroscope of claim 1 wherein the first proof mass responds to an angular velocity about the input axis normal to the plane of the gyroscope.

13. The gyroscope of the claim 1 wherein the first proof mass responds to an angular velocity about the input axis in the plane of the gyroscope.

14. The gyroscope of claim 1 wherein the first proof mass oscillates at a frequency greater than 20 kHz.