Inertial sensor with a linear array of sensor elements

• US 20050229705A1
• Filed: 04/14/2005
• Published: 10/20/2005
• Est. Priority Date: 04/14/2004
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Geen, John A.
• Granted Patent: US 7,287,428 B2
• Time in Patent Office: Days
• US Class Current: 73/514.160
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01C 19/574 the devices having two sensing masses in anti-phase motion

Abstract

An inertial sensor includes at least one pair of sensor elements arranged in a linear array. Each sensor element has a frame and a movable mass suspended within the frame. The frames of each pair of sensor elements may be coupled so that the frames are allowed to move in anti-phase to one another along parallel axes but are substantially prevented from moving in phase with one another.

Claims

1. An inertial sensor comprising:

at least one substrate; and

at least two pairs of sensor elements configured in a linear array substantially in a plane above the at least one substrate, each pair of sensor elements including;

a first sensor element having a first resonator suspended within a first frame; and

a second sensor element having a second resonator suspended within a second frame, wherein;

all of the frames are substantially aligned along a first axis in the plane and the frames of each pair are configured to move in anti-phase to one another along parallel axes in the plane normal to the first axis.

2. An inertial sensor according to claim 1, wherein the first and second resonators are caused to move co-linearly and in anti-phase to one another along the first axis.

3. An inertial sensor according to claim 1, wherein rotation of the at least one substrate about an axis normal to the plane causes the movements of the frames.

4. An inertial sensor according to claim 1, wherein each pair of sensor elements further includes:

a first coupling interconnecting the first and second frames.

5. An inertial sensor according to claim 4, wherein the first coupling comprises:

at least one bar coupled between the first and second frames, the at least one bar supported by structures anchored to the at least one substrate, the structures allowing the at least one bar to rotate at a pivot point when the frames move in anti-phase to one another but substantially preventing in-phase movements of the frames.

6. An inertial sensor according to claim 5, wherein the first coupling comprises:

a first pair of short flexures extending from one of the frames and interconnected by a first long flexure;

a second pair of short flexures extending from the other of the frames and interconnected by a second long flexure;

a bar coupling the first long flexure to the second long flexure substantially at the midpoints of the first and second long flexures; and

an anchor flexure supporting the bar, the anchor flexure intersecting with the bar substantially at the midpoints of the bar and the anchor flexure, each end of the anchor flexure anchored to the substrate.

7. An inertial sensor according to claim 5, wherein the first coupling comprises:

a first flexure extending from one of the frames;

a second flexure extending from the other of the frames;

a bar coupled between the first and second flexures; and

at least one anchor flexure supporting the bar, each anchor flexure including a structure anchored at one end to the at least one substrate and folded back 180 degrees to meet with the bar.

8. An inertial sensor according to claim 1, wherein the placement of the inertial sensors and the phase of the resonators are coordinated so as to share a common centroid.

9. An inertial sensor according to claim 1, wherein each frame includes finger structures that interdigitate with fixed sensing fingers anchored to the at least one substrate for electrostatically sensing the movements of the frames.

10. An inertial sensor according to claim 1, wherein each resonator includes finger structures that interdigitate with fixed drive fingers anchored to the at least one substrate for electrostatically moving the resonators.

11. An inertial sensor according to claim 1, wherein the second frame of one pair is adjacent to the first frame of another pair, and wherein said adjacent frames are configured to operate in phase with one another.

12. An inertial sensor comprising:

at least one substrate; and

at least two pairs of sensor elements configured in a linear array substantially in a plane above the at least one substrate, each pair of sensor elements including;

a first sensor element having a first resonator suspended within a first frame; and

a second sensor element having a second resonator suspended within a second frame, wherein;

all of the frames are substantially aligned along a first axis in the plane, and wherein the inertial sensor further comprises means for operating the frames of each pair of sensor elements in anti-phase to one another along parallel axes in the plane normal to the first axis.

13. An inertial sensor according to claim 12, further comprising:

means for moving the resonators such that the first and second resonators are caused to move co-linearly and in anti-phase to one another along the first axis.

14. An inertial sensor according to claim 12, wherein rotation of the at least one substrate about an axis normal to the plane causes the movements of the frames.

15. An inertial sensor according to claim 12, further comprising:

means for interconnecting the first and second frames of each pair of sensor elements.

16. An inertial sensor according to claim 15, wherein the interconnecting means comprises:

at least one bar coupled between the first and second frames; and

means for supporting the at least one bar so as to allow the at least one bar to rotate at a pivot point when the frames move in anti-phase to one another but substantially prevent in-phase movements of the frames.

17. An inertial sensor according to claim 16, wherein the interconnecting means comprises:

a first pair of short flexures extending from one of the frames and interconnected by a first long flexure;

a second pair of short flexures extending from the other of the frames and interconnected by a second long flexure;

a bar coupling the first long flexure to the second long flexure substantially at the midpoints of the first and second long flexures; and

an anchor flexure supporting the bar, the anchor flexure intersecting with the bar substantially at the midpoints of the bar and the anchor flexure, each end of the anchor flexure anchored to the substrate.

18. An inertial sensor according to claim 16, wherein the interconnecting means comprises:

a first flexure extending from one of the frames;

a second flexure extending from the other of the frames;

a bar coupled between the first and second flexures; and

at least one anchor flexure supporting the bar, each anchor flexure including a structure anchored at one end to the at least one substrate and folded back 180 degrees to meet with the bar.

19. An inertial sensor according to claim 12, wherein the placement of the inertial sensors and the phase of the resonators are coordinated so as to share a common centroid.

20. An inertial sensor according to claim 12, further comprising:

means for sensing the movements of the frames.

21. An inertial sensor according to claim 12, wherein the second frame of one pair is adjacent to the first frame of another pair, and wherein said adjacent frames are configured to operate in phase with one another.