MEMS SENSOR WITH DECOUPLED DRIVE SYSTEM

• US 20150211853A1
• Filed: 04/03/2015
• Published: 07/30/2015
• Est. Priority Date: 09/16/2011
• Status: Active Grant

• Current Assignee: Invensense Incorporated (TDK Corporation)
• Original Assignee: Invensense Incorporated (TDK Corporation)
• Inventors: SEEGER, Joseph, ANAC, Ozan
• Granted Patent: US 9,863,769 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

In a first aspect, the angular rate sensor comprises a substrate and a rotating structure anchored to the substrate. The angular rate sensor also includes a drive mass anchored to the substrate and an element coupling the drive mass and the rotating structure. The angular rate sensor further includes an actuator for driving the drive mass into oscillation along a first axis in plane to the substrate and for driving the rotating structure into rotational oscillation around a second axis normal to the substrate; a first transducer to sense the motion of the rotating structure in response to a Coriolis force in a sense mode; and a second transducer to sense the motion of the sensor during a drive mode. In a second aspect the angular rate sensor comprises a substrate and two shear masses which are parallel to the substrate and anchored to the substrate via flexible elements.

Claims

1. An angular rate sensor comprising;

a substrate;

a rotating structure coupled to the substrate;

a drive mass coupled to the substrate;

a flexible element coupling the drive mass and the rotating structure;

an actuator coupled to the rotating structure via the drive mass for driving the rotating structure into rotational oscillation around a first axis normal to the substrate;

a first transducer responsive to the rotational oscillation of the rotating structure during a drive mode; and

a second transducer which is responsive to the angular velocity of the angular rate sensor.

2. The angular rate sensor of claim 1, wherein the first transducer is attached to the rotating structure.

3. The angular rate sensor of claim 1, wherein the rotating structure comprises any of a rectangular proof mass or a circular proof mass.

4. The angular rate sensor of claim 1, wherein the drive mass is driven in a translational mode.

5. The angular rate sensor of claim 1, wherein an amplitude of the rotating structure is dependent upon the drive mass motion and the coupling element stiffness.

6. The sensor of claim 1, wherein at least one first proof mass is flexibly coupled to the rotating structure and the at least one first proof mass responds to a Coriolis force.

7. The sensor of claim 1, wherein the rotating structure responds to a Coriolis force.

8. The sensor of claim 1, wherein the rotating structure is flexibly coupled to an at least one first translational mass and wherein the first translational mass is flexibly coupled to the substrate and translates along a second axis which is parallel to the substrate.

9. The angular rate sensor of claim 8, wherein the first transducer is attached to the first translational mass.

10. The sensor of claim 8, includes a second translational mass, wherein the second translational mass is flexibly coupled to the substrate and translates along a third axis which is parallel to the substrate and to the second axis and wherein the first and second translational mass moves out of phase along the second and the third axis, respectively.

11. The sensor of claim 10, wherein the first and second translational masses are able to move anti-phase in response to a Coriolis force acting in a direction that is normal to the substrate generated by an angular rate around a fourth axis that is in-plane and orthogonal to the second axis.

12. The sensor of claim 5, wherein the drive mass and the rotating structure forms a mechanical system with two-degrees of freedom.

13. The sensor of claim 12, wherein motion of the drive mass is less than the motion of the rotating structure.

14. The sensor of claim 8, wherein a proof mass is flexibly connected to the first translational mass via a first spring and flexibly connected to the second translational mass via a second spring and rotates around an axis orthogonal to the substrate while the drive mass is driven in a first direction.

15. The sensor of claim 14, wherein the proof mass responds to a Coriolis force generated by an angular rate around an axis parallel to the substrate and orthogonal to the first axis.

16. The sensor of claim 10, wherein a proof mass is flexibly connected to the first translational mass which is able to move in the same direction as the second translational mass.

17. The sensor of claim 16, wherein a second proof mass is flexibly connected to a second translational mass which is able to move in the same direction as the first translational mass.

18. The sensor of claim 16, wherein the proof masses is able to move in response to a Coriolis force acting in a direction that is parallel to the first axis generated by an angular rate around an axis that is orthogonal to the substrate.

19. The sensor of claim 1, further comprising a suspension system coupling the drive mass to the substrate, wherein the suspension system is stiffer than the flexible element while rotating out of plane.

20. An angular rate sensor comprising;

a substrate;

a first and second shear masses coupled to the substrate;

a drive mass coupled to the substrate;

a flexible element coupling the drive mass and the first and second shear masses;

an actuator coupled to and the first and second shear masses via the drive mass for driving the and the first and second shear masses into anti-phase oscillation along a first and second direction parallel to each other;

a first transducer responsive to the anti-phase oscillation during a drive mode; and

a second transducer which is responsive to the angular velocity of the angular rate sensor.

21. The sensor of claim 20, wherein the first transducer is attached to the shear mass.

22. The sensor of claim 20, wherein the first and second shear masses are coupled to each other.

23. The sensor of claim 20. wherein the drive mass and the first and second shear masses forms a mechanical system with two-degrees of freedom and wherein motion of the drive mass is less than the motion of the first and second proof masses.

24. The sensor of claim 20, wherein the first and second shear masses are flexibly coupled to a first translational mass and wherein the first translational mass is flexibly coupled to the substrate and translates along a second axis which is parallel to the substrate.

25. The sensor of claim 24, wherein a proof mass is flexibly connected to the first translational mass via a first spring and flexibly connected to a second translational mass via a second spring and rotates around an axis orthogonal to the substrate while the drive mass is driven in a first direction.

26. The sensor of claim 25, wherein a second proof mass is flexibly connected to the first translational mass which is able to move in the same direction as the second translational mass.