Ring gyroscope structural features
Novel structural features applicable to a variety of inertial sensors. A composite ring composed of concentric subrings is supported by a compliant support structure suspending the composite ring relative to a substrate. The compliant support structure may either be interior or exterior to the composite ring. The compliant support may be composed of multiple substantially concentric rings coupled to neighboring rings by transverse members regularly spaced at intervals that vary with radius relative to a central axis of symmetry. Subrings making up the composite ring may vary in width so as to provide larger displacement amplitudes at intermediate radii, for example. In other embodiments, electrodes are arranged to reduce sensitivity to vibration and temperature, and shock stops are provided to preclude shorting in response to shocks.
1. A micro-scale gyroscope resonator comprising:
a composite ring comprising a first plurality of rings lying substantially in a plane and including at least a first ring having a first inner diameter and a first outer diameter, a second ring having a second inner diameter and a second outer diameter and a third ring having a third inner diameter and a third outer diameter, the composite ring being configured to exhibit an oscillation mode whereby an outermost ring of the first plurality of rings and an innermost ring of the first plurality of rings have substantially equal displacement amplitudes, wherein:
the first inner diameter is different from the second inner diameter and the third inner diameter,
a difference between the first outer diameter and the first inner diameter is different from a difference between the second outer diameter and the second inner diameter,
the difference between the first outer diameter and the first inner diameter is different from a difference between the third outer diameter and the third inner diameter, and
the difference between the second outer diameter and the second inner diameter is different from the difference between the third outer diameter and the third inner diameter;
a first electrode positioned inside the composite ring and a second electrode positioned outside the composite ring; and
a compliant support structure adapted to suspend the first plurality of rings relative to a substrate.
2. A micro-scale gyroscope resonator according to claim 1 , wherein
the first inner diameter is greater than the second inner diameter and the second inner diameter is greater than the third inner diameter,
the difference between the first outer diameter and the first inner diameter is greater than the difference between the second outer diameter and the second inner diameter, and
the difference between the second outer diameter and the second inner diameter is greater than the difference between the third outer diameter and the third inner diameter.
3. A micro-scale gyroscope resonator according to claim 1 , wherein the oscillation mode is such that the first plurality of rings produce a same amount of displacement.
4. A micro-scale gyroscope resonator according to claim 1 , wherein the first plurality of rings are concentric.
5. A micro-scale gyroscope resonator according to claim 1 , wherein the first plurality of rings are coupled to one another via a plurality of coupling beams.
6. A micro-scale gyroscope resonator according to claim 1 , further comprising at least one actuator positioned in correspondence with an anti-node of the composite ring.
7. A micro-scale gyroscope resonator according to claim 1 , wherein the compliant support structure comprises a second plurality of rings including at least a fourth ring, a fifth ring and a sixth ring, wherein the fourth ring is coupled to the fifth ring only via a first plurality of coupling beams and the fifth ring is coupled to the sixth ring only via a second plurality of coupling beams, the first plurality of coupling beams being angularly offset relative to the second plurality of coupling beams.
8. A micro-scale gyroscope resonator according to claim 7 , wherein at least one of the first plurality of coupling beams is stiff.
9. A micro-scale gyroscope resonator according to claim 7 , wherein all of the first plurality of coupling beams are stiff.
10. A micro-scale gyroscope resonator according to claim 7 , wherein the first plurality of coupling beams are spaced from one another at equal spacing angles.
11. A micro-scale gyroscope resonator according to claim 7 , wherein the second plurality of rings are concentric.
12. A micro-scale gyroscope resonator according to claim 7 , wherein the first plurality of coupling beams have first ends adjacent the fourth ring and second ends adjacent the fifth ring, and wherein the second plurality of coupling beams have first ends adjacent the fifth ring and second ends adjacent the sixth ring.
13. A micro-scale gyroscope resonator according to claim 1 , wherein the compliant support structure is coupled to the substrate via an anchor interior to all of the first plurality of rings.
14. A micro-scale gyroscope resonator according to claim 1 , wherein the first electrode is a drive electrode and the second electrode is a sense electrode.
15. A micro-scale gyroscope resonator comprising:
a composite ring comprising a first plurality of rings lying substantially in a plane and including at least a first ring having a first inner diameter, a first outer diameter and a first annular width, a second ring having a second inner diameter, a second outer diameter and a second annular width and a third ring having a third inner diameter, a third outer diameter and a third annular width;
a first electrode positioned inside the composite ring and a second electrode positioned outside the composite ring; and
a compliant support structure adapted to suspend the first plurality of rings relative to a substrate,
wherein the first inner diameter is greater than the second inner diameter and the second inner diameter is greater than the third inner diameter, and wherein the first annular width is greater than the second annular width and the second annular width is greater than the third annular width, and
wherein the composite ring is configured to exhibit an oscillation mode whereby an outermost ring of the first plurality of rings and an innermost ring of the first plurality of rings have substantially equal displacement amplitudes.
16. A micro-scale gyroscope resonator according to claim 15 , wherein the oscillation mode is such that the first plurality of rings produce a same amount of displacement.
17. A micro-scale gyroscope resonator according to claim 15 , wherein the compliant support structure comprises a second plurality of rings including at least a fourth ring, a fifth ring and a sixth ring.
18. A micro-scale gyroscope resonator according to claim 17 , wherein the fourth ring is coupled to the fifth ring only via a first plurality of coupling beams and the fifth ring is coupled to the sixth ring only via a second plurality of coupling beams, the first plurality of coupling beams being angularly offset relative to the second plurality of coupling beams.
19. A micro-scale gyroscope resonator according to claim 18 , wherein the first plurality of coupling beams are spaced from one another at equal spacing angles.
20. A micro-scale gyroscope resonator according to claim 15 , wherein the compliant support structure is coupled to the substrate via an anchor interior to all of the first plurality of rings.