Oscillating micro-mechanical sensor of angular velocity

• US 20060156814A1
• Filed: 12/28/2005
• Published: 07/20/2006
• Est. Priority Date: 12/31/2004
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: VTI Technologies Oy (Murata Manufacturing Co Limited)
• Inventors: Blomqvist, Anssi
• Granted Patent: US 7,454,971 B2
• Time in Patent Office: Days
• US Class Current: 73/504.120
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

The invention relates to measuring devices used in measuring angular velocity, and, more specifically, to oscillating micro-mechanical sensors of angular velocity. In the sensor of angular velocity according to the present invention seismic masses (1), (2), (36), (37) are connected to support areas by means of springs or by means of springs and stiff auxiliary structures, which give the masses (1), (2), (36), (37) a degree of freedom in relation to an axis of rotation perpendicular to the plane of the wafer formed by the masses, and in relation to at least one axis of rotation parallel to the plane of the wafer. The structure of the sensor of angular velocity according to the present invention enables reliable and efficient measuring particularly in compact oscillating micro-mechanical sensors of angular velocity.

Claims

1. An oscillating micro-mechanical sensor of angular velocity, said sensor comprising two seismic masses (1), (2), (36), (37), which are attached to the body of the sensor component at support areas, and a connecting spring between the masses (1), (2), (36), (37), such that

the primary motion of the sensor of angular velocity, which motion must be generated, is an opposite phase angular oscillation of the two seismic masses (1), (2), (36), (37) about the support areas,

the seismic masses (1), (2), (36), (37) are connected to each other by means of at least one bending spring (11), (50), which mechanically synchronizes their primary motion, and that

the seismic masses (1), (2), (36), (37) are connected to the support areas by means of springs, or by means of springs and stiff auxiliary structures, which give the masses (1), (2), (36), (37) a degree of freedom in relation to an axis of rotation perpendicular to the plane of the disk formed by the masses, and in relation to at least one axis of rotation in the direction of the plane of said disk.

2. Sensor of angular velocity according to claim 1, wherein the sensor of angular velocity is a sensor of angular velocity measuring angular velocity in relation to one axis, the sensor having two seismic masses (1), (2) attached to the body of the sensor component at least two attachment spots (3), (4).

3. Sensor of angular velocity according to claim 2, wherein the bending spring (11) is essentially higher than it is wide.

4. Sensor of angular velocity according to claim 2, wherein the sensor of angular velocity comprises

rotary springs (5), (6) for the primary motion, which springs have flexibility in relation to the primary motion, and

torsion springs (7)-(10) for the detection motion, which springs have flexibility in relation to a torsion oscillation caused by a torque moment generated by an external angular velocity.

5. Sensor of angular velocity according to claim 2, wherein the oscillation caused by the external angular velocity is detected in a capacitive manner by means of electrodes located above or underneath the masses (1), (2).

6. Sensor of angular velocity according to claim 5, wherein the electrodes are grown onto the inner surface of a wafer hermetically closing the sensor structure.

7. Sensor of angular velocity according to claim 2, wherein the sensor of angular velocity comprises a second bending spring extending essentially in the same direction as, and attached at the center point of, the spring (11) connecting the masses of the sensor of angular velocity.

8. Sensor of angular velocity according to claim 2, wherein the masses (1), (2) are attached to the body by means of attachment spots (3), (4), and additionally by means of attachment spots (12), (13) installed at the center.

9. Sensor of angular velocity according to claim 2, wherein the masses (1), (2) are attached to the body by means of attachment spots (3), (4), and additionally by means of attachment spots (14)-(17) installed in the corners or at the edge.

10. Sensor of angular velocity according to claim 2, wherein the masses (1), (2) are attached to the body by means of attachment spots (18), (19), which attachment spots (18), (19) at one side are attached to the masses (1), (2) by means of designed stiff auxiliary structures.

11. Sensor of angular velocity according to claim 2, wherein the masses (1), (2) are attached to the body by means of attachment spots (18), (19), which attachment spots (18), (19) at one side are attached to the masses (1), (2) by means of springs.

12. Sensor of angular velocity according to claim 2, wherein the masses (1), (2) are attached to the body by means of attachment spots (24), (25), which are installed at the center of the ends, and additionally by means of attachment spots (20), (21), which attachment spots (20), (21) at one side, are attached to the masses (1), (2) by means of springs (22), (23).

13. Sensor of angular velocity according to claim 2, wherein the sensor of angular velocity comprises strain relieving structures (26), (27).

14. Sensor of angular velocity according to claim 2, wherein the sensor of angular velocity comprises a comb structure (28), (29).

15. Sensor of angular velocity according to claim 2, wherein the sensor of angular velocity comprises radial comb structures (34), (35).

16. Sensor of angular velocity according to claim 1, wherein the sensor of angular velocity is a sensor of angular velocity measuring angular velocity in relation to two axes, the sensor containing two seismic masses (36), (37) attached to the body of the sensor component by means of two attachment spots (38), (39).

17. Sensor of angular velocity according to claim 16, wherein the bending spring (50) is essentially higher than it is wide.

18. Sensor of angular velocity according to claim 16, wherein the sensor of angular velocity comprises

rotary springs (40), (41) for the primary motion, which springs have flexibility in relation to the primary motion,

torsion springs (42)-(45) for the detection motion in a first direction, which springs have flexibility in relation to the detection motion in the first direction, and

torsion springs (46)-(49) for the detection motion in a second direction, which springs have flexibility in relation to the detection motion in the second direction.

19. Sensor of angular velocity according to claim 16, wherein the oscillation caused by the external angular velocity is detected in a capacitive manner by means of electrodes located above or underneath the masses (36), (37).

20. Sensor of angular velocity according to claim 19, wherein the electrodes are grown onto the inner surface of a wafer hermetically closing the sensor structure.

21. Sensor of angular velocity according to claim 2, wherein the attachment spots (3), (4), (14)-(19), (20), (21), (24), (25), (30), (31) are joined in an anodic manner to the wafer hermetically closing the sensor structure.

22. Sensor of angular velocity according to claim 2, wherein the attachment spots (3), (4), (14)-(19), (20), (21), (24), (25), (30), (31) are joined by means of a fusion joint to the wafer hermetically closing the sensor structure.