Micromachined apparatus with split vibratory masses

• US 7,216,539 B2
• Filed: 02/23/2006
• Issued: 05/15/2007
• Est. Priority Date: 02/06/2002
• Status: Expired due to Term

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Geen, John A.
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US11/360,848
• Publication Number:
  US 20060191340A1
• Time in Patent Office: 446 Days
• Field of Search: 735/041.2, 735/041.4, 735/040.4, 735/041.6, 735/143.2, 735/143.6, 735/143.8, 735/141.6, 735/142.9
• US Class Current: 73/504.14
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: Y10T 74/12 Gyroscopes

Abstract

Each of a number of resonator masses is split into two separate lobes or masses joined together by a short flexure. The short flexure allows the separate lobes or masses to rotate slightly as they resonate so as to substantially relieve longitudinal stresses in certain resonator structures.

Claims

1. Apparatus comprising a plurality of resonator structures including a pair of split masses suspended by suspension flexures, wherein each split mass includes two lobes interconnected with a flexure that allows the lobes to rotate slightly as the masses resonate so as to reduce longitudinal stresses in the suspension flexures.

2. Apparatus according to claim 1, wherein the pair of split masses are interconnected through a plurality of levers so as to resonate in anti-phase with one another, wherein the rotation of the lobes reduces longitudinal stresses in the levers.

3. Apparatus according to claim 2, wherein the plurality of levers transform the coupled motion of the lobes from co-linear motion to parallel motion.

4. Apparatus according to claim 1, wherein each lobe includes a plurality of drive fingers interdigitated with a corresponding array of fixed drive fingers affixed to a substrate.

5. Apparatus according to claim 1, wherein each lobe comprises at least one notch for electronic quadrature suppression.

6. Apparatus according to claim 2, wherein the plurality of resonator structures are suspended within an inner perimeter of a frame and wherein the resonator structures are mechanically coupled to produce substantially a single resonance frequency so as to restrict transfer of inertial forces to the frame.

7. Apparatus according to claim 6, wherein each of the plurality of levers is coupled at one end to the frame and at another end to a different one of the lobes, and wherein each lever has pivots, defined at the points of attachment to the frame and the lobe by the intersection of the axes of at least two orthogonal flexures, to ensure that the attachment point cannot translate with respect to the lever.

8. Apparatus according to claim 2, wherein each of the levers includes a plurality of lever fingers interdigitated with corresponding fixed fingers affixed to an underlying substrate for at least one of driving the lever and sensing position of the lever.

9. Apparatus according to claim 8, wherein each of the levers moves with an arcuate motion, and wherein the lever fingers are disposed at varying angles so as to maintain substantially equal distances from said corresponding fixed fingers during movement of the levers.

10. Apparatus according to claim 1, wherein the plurality of resonator structures are micromachined from a single wafer.

11. Apparatus comprising a plurality of resonator structures including a first pair of masses coupled through a first flexure and a second pair of masses coupled through a second flexure, each mass suspended by a suspension flexure, wherein the first and second flexures allow the masses to rotate slightly as the masses resonate so as to reduce longitudinal stresses in the suspension flexures.

12. Apparatus according to claim 11, wherein the first and second pairs of masses are interconnected through a plurality of levers so as to resonate in anti-phase with one another, wherein the rotation of the masses reduces longitudinal stresses in the levers.

13. Apparatus according to claim 12, wherein the plurality of levers transform the coupled motion of the masses from co-linear motion to parallel motion.

14. Apparatus according to claim 11, wherein each mass includes a plurality of drive fingers interdigitated with a corresponding array of fixed drive fingers affixed to a substrate.

15. Apparatus according to claim 11, wherein each mass comprises at least one notch for electronic quadrature suppression.

16. Apparatus according to claim 12, wherein the plurality of resonator structures are suspended within an inner perimeter of a frame and wherein the resonator structures are mechanically coupled to produce substantially a single resonance frequency so as to restrict transfer of inertial forces to the frame.

17. Apparatus according to claim 16, wherein each of the plurality of levers is coupled at one end to the frame and at another end to a different one of the masses, and wherein each lever has pivots, defined at the points of attachment to the frame and the mass by the intersection of the axes of at least two orthogonal flexures, to ensure that the attachment point cannot translate with respect to the lever.

18. Apparatus according to claim 12, wherein each of the levers includes a plurality of lever fingers interdigitated with corresponding fixed fingers affixed to an underlying substrate for at least one of driving the lever and sensing position of the lever.

19. Apparatus according to claim 18, wherein each of the levers moves with an arcuate motion, and wherein the lever fingers are disposed at varying angles so as to maintain substantially equal distances from said corresponding fixed fingers during movement of the levers.

20. Apparatus according to claim 11, wherein the plurality of resonator structures are micromachined from a single wafer.