Angular-rate detecting apparatus

• US 20050066726A1
• Filed: 08/24/2004
• Published: 03/31/2005
• Est. Priority Date: 09/29/2003
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Mochida, Yoichi
• Granted Patent: US 7,093,487 B2
• Time in Patent Office: Days
• US Class Current: 73/504.140
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis

Abstract

An Angular-rate detecting apparatus includes four mass portions connected by at least one support beam, and the mass portions have respective individual vibration generators disposed thereon. The individual vibration generators excite the normal vibration mode by vibrating pairs of the mass portions adjacent to each other in opposite phases. Thus, the mass portions are forcibly vibrated in the normal vibration mode. Angular rate detectors detect displacements of inner frames of central mass portions as an angular rate about an axis perpendicular to a detection direction and also to a vibration direction when the inner frames are displaced in the detection direction while vibrating in the vibration direction.

Claims

1. An angular-rate detecting apparatus, comprising:

a substrate;

a plurality of mass portions juxtaposed to one another on the substrate in a predetermined direction;

a support beam connecting the plurality of mass portions so as to enable each of the plurality of mass portions to be vibratable in a vibration direction substantially perpendicular to the predetermined direction along which the plurality of mass portions are juxtaposed to one another;

a fixing portion fixing the support beam to the substrate;

vibration generators vibrating two of the plurality of mass portions adjacent to each other in opposite phases in the vibration direction; and

an angular rate detector detecting a displacement of a portion of the mass portions as an angular rate, displaced in a detection direction substantially perpendicular to the vibration direction in a state in which the mass portions are vibrating;

wherein

the vibration generators exert drive forces on the two mass portions adjacent to each other in opposite directions to each other.

2. The angular-rate detecting apparatus according to claim 1, wherein the vibration generators are individually disposed as individual vibration generators corresponding to the respective mass portions, and two of the individual vibration generators adjacent to each other generate drive forces in the opposite directions from each other.

3. The angular-rate detecting apparatus according to claim 1, wherein, among the plurality of mass portions, the ratio among the magnitudes of drive forces exerted on the respective mass portions by the vibration generators is substantially the same as the ratio among the products of masses and driven amplitudes of the corresponding mass portions.

4. The angular-rate detecting apparatus according to claim 1, wherein the plurality of mass portions includes four pieces of mass portions linearly juxtaposed to one another.

5. The angular-rate detecting apparatus according to claim 1, wherein the support beam includes outer support beam portions and inner support beam portions connecting the plurality of mass portions to one another.

6. The angular-rate detecting apparatus according to claim 1, wherein the plurality of mass portions are arranged symmetrically about a center of gravity of the angular-rate detecting apparatus.

7. The angular-rate detecting apparatus according to claim 1, wherein the fixing portion includes quadrangular mounts fixed on the substrate and arranged so as to surround the plurality of mass portions, extending portions disposed on side portions of the substrate and integral with the quadrangular mounts, and elastic arm portions disposed on the extend portions, connected to node portions of the support beam, and arranged so as to be spaced away from the substrate.

8. The angular-rate detecting apparatus according to claim 1, wherein each of the vibration generators includes a fixed drive electrode disposed on the substrate and a movable drive electrode disposed on a respective one of the plurality of mass portions.

9. The angular-rate detecting apparatus according to claim 8, wherein the fixed drive electrode includes a plurality of electrode plates disposed side by side in a comb shaped configuration and the movable drive electrode includes a plurality of electrode plates disposed side by side in a comb shaped configuration, the fixed drive electrode and the movable drive electrode are arranged such that the plurality of electrode plates of the fixed drive electrode are interdigitated with the plurality of electrode plates of the movable drive electrode.

10. The angular-rate detecting apparatus according to claim 1, wherein the angular rate detector includes a fixed detection electrode disposed on the substrate and a movable detection electrode disposed on a respective one of the plurality of mass portions.

11. The angular-rate detecting apparatus according to claim 10, wherein the fixed detection electrode includes a plurality of electrode plates disposed side by side in a comb shaped configuration and the movable detection electrode includes a plurality of electrode plates disposed side by side in a comb shaped configuration, the fixed detection electrode and the movable detection electrode are arranged such that the plurality of electrode plates of the fixed detection electrode are interdigitated with the plurality of electrode plates of the movable detection electrode.

12. An angular-rate detecting apparatus, comprising:

a substrate;

a plurality of mass portions juxtaposed to one another on the substrate in a predetermined direction;

a support beam connecting the plurality of mass portions so as to enable each of the plurality of mass portion to be vibratable in a vibration direction substantially perpendicular to the predetermined direction along which the plurality of mass portions are juxtaposed to one another;

a fixing portion fixing the support beam to the substrate; and

an angular rate detector detecting displacement of a portion of the plurality of mass portions as an angular rate, displaced in a detection direction substantially perpendicular to the vibration direction in a state in which the mass portions are vibrating;

wherein

at least one of the plurality of mass portions has a vibration generator disposed thereon, and another one of plurality of mass portions adjacent to said at least one of the plurality of mass portions has a vibration monitor disposed thereon, monitoring vibrating state thereof and outputting monitor signal for controlling the vibration generator such that mass portions adjacent to each other vibrate in opposite phases in the vibration direction.

13. The angular-rate detecting apparatus according to claim 12, wherein the vibration monitor outputs a normal monitor signal when said at least one of the plurality of mass portions and said another one of the plurality of mass portions vibrate in opposite phases, and the vibration generator and the vibration monitor have a control circuit disposed therebetween, the control circuit maintains each of the plurality of mass portions in a resonant state by the vibration generator when the normal monitor signal is inputted to the control circuit from the vibration monitor.

14. The angular-rate detecting apparatus according to claim 12, wherein the plurality of mass portions includes four pieces of mass portions linearly juxtaposed to one another.

15. The angular-rate detecting apparatus according to claim 12, wherein the support beam includes outer support beam portions and inner support beam portions connecting the plurality of mass portions to one another.

16. The angular-rate detecting apparatus according to claim 12, wherein the plurality of mass portions are arranged symmetrically about the center of gravity of the angular-rate detecting apparatus.

17. The angular-rate detecting apparatus according to claim 12, wherein the fixing portion includes quadrangular mounts fixed on the substrate and arranged so as to surround the plurality of mass portions, extending portions disposed on side portions of the substrate and integral with the quadrangular mounts, and elastic arm portions disposed on the extend portions, connected to node portions of the support beam, and arranged so as to be spaced away from the substrate.

18. The angular-rate detecting apparatus according to claim 12, wherein the vibration generator includes a fixed drive electrode disposed on the substrate and a movable drive electrode disposed on a respective one of the plurality of mass portions.

19. The angular-rate detecting apparatus according to claim 18, wherein the fixed drive electrode includes a plurality of electrode plates disposed side by side in a comb shaped configuration and the movable drive electrode includes a plurality of electrode plates disposed side by side in a comb shaped configuration, the fixed drive electrode and the movable drive electrode are arranged such that the plurality of electrode plates of the fixed drive electrode are interdigitated with the plurality of electrode plates of the movable drive electrode.

20. The angular-rate detecting apparatus according to claim 12, wherein the angular rate detector includes a fixed detection electrode disposed on the substrate and a movable detection electrode disposed on a respective one of the plurality of mass portions.

21. The angular-rate detecting apparatus according to claim 20, wherein the fixed detection electrode includes a plurality of electrode plates disposed side by side in a comb shaped configuration and the movable detection electrode includes a plurality of electrode plates disposed side by side in a comb shaped configuration, the fixed detection electrode and the movable detection electrode are arranged such that the plurality of electrode plates of the fixed detection electrode are interdigitated with the plurality of electrode plates of the movable detection electrode.