Angular velocity sensor

• US 6,308,567 B1
• Filed: 12/10/1999
• Issued: 10/30/2001
• Est. Priority Date: 12/10/1998
• Status: Expired due to Term

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Higuchi, Hirofumi, Fukada, Tsuyoshi, Ohya, Nobuyuki
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US09/458,954
• Time in Patent Office: 690 Days
• Field of Search: 735/041.2, 735/041.3, 735/041.4, 735/040.4, 735/040.2, 735/040.8, 735/041.8
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces

Abstract

A compact angular velocity sensor, which can improve an S/N (signal/noise) ratio. An angular velocity sensor includes an SOI substrate, four oscillatory masses movably supported to the SOI substrate, and four detection electrodes provided outer side of the oscillatory masses for detecting displacements of the oscillatory masses. The oscillatory masses are arranged point-symmetry with respect to a predetermined point K in a flat plane parallel to the SOI substrate. Each of the four oscillatory masses adjacent each other is oscillated in reverse phase in a circumstantial direction about the predetermined point K along the flat plane. When an angular velocity Ω is generated about the predetermined point K, detection weights of the oscillatory masses are displaced along a direction perpendicular to oscillation direction in the flat plane. Capacitance changes between the detection weights and the detection electrodes are processed in a circuit portion so as to output angular velocity detection signal S1 due to Corioli'"'"'s force with canceling external acceleration and centrifugal force acted to the detection weights of the oscillatory masses.

Claims

1. An angular velocity sensor comprising:

a substrate;

a plurality of movable portions movably supported on the substrate, being point-symmetry arranged from each other with respect to a predetermined point and being movable in a circumferential direction centering the predetermined point, and being arranged so as to be movable in a radial direction parallel to a surface of the substrate with respect to the predetermined point when angular velocity is generated around the predetermined point on a condition that the plurality of movable portions oscillate in the circumferential direction; and

a detection portion confronted with the movable portions for detecting displacement of the movable portions in the radial direction in accordance with the angular velocity.

2. An angular velocity sensor according to claim 1, wherein the movable portions include a first movable portion and a second movable portion confronted with the first movable portion with the predetermined point interposed therebetween, and the first movable portion and the second movable portion are to be oscillated in the same phase.

3. An angular velocity sensor according to claim 1, wherein the number of the movable portions is selected from an even number.

4. An angular velocity sensor according to claim 1, wherein:

the number of the movable portions is selected from multiples of four,

every two movable portions being point-symmetry arranged from each other with respect to the predetermined point are to be oscillated in the same phase, and

one half of the movable portions and another one half of the movable portions are oscillated in reverse phase.

5. An angular velocity sensor according to claim 4, wherein each of the movable portions adjacent to each other is oscillated in reverse phase.

6. An angular velocity sensor according to claim 1, wherein the detection portion is arranged on an outer side of the movable portions in the radial direction with respect to the predetermined point.

7. An angular velocity sensor according to claim 1, further comprising:

a circuit portion for inputting an angular velocity signal from the detection portion for processing so as to output a signal due to Corioli'"'"'s force acted to the movable portions.

8. An angular velocity sensor according to claim 7, wherein the circuit portion processes so as to output a signal due to Corioli'"'"'s force acted to the movable portions with substantially canceling an external force acted on the movable portions.

9. An angular velocity sensor according to claim 1, wherein the detection portion comprises fixed electrodes fixed to the substrate so as to confront with the movable portions, for detecting capacitance changes between the fixed electrodes and the movable portions as a result of displacement of the movable portions along a flat plane parallel to the substrate.

10. An angular velocity sensor according to claim 1, wherein each of the movable portions comprises

a first elastic member elastically deformable along an oscillation direction;

an oscillation portion supported to the substrate via the first elastic member;

a second elastic member connected to the oscillation portion, and being elastically deformable along a direction perpendicular to the oscillation direction in a flat plane parallel to the substrate; and

a detection weight supported to the oscillation portion via the second elastic member.

11. An angular velocity sensor according to claim 10, wherein:

the substrate has a driving electrode having a comb-shape for confronting with the oscillation portion;

the oscillation portion has a confront electrode having a comb-shape for confronting with the driving electrode so as to mesh with the comb-shape of the driving electrode, and

the driving electrode is for generating electrostatic force between the driving electrode and the confront electrode so as to oscillate the movable portions by applying an alternating voltage between the driving electrode and the confront electrode.

12. An angular velocity sensor according to claim 1, wherein the detection portion faces the movable portions in the radial direction, and detects changes in capacitance between the detection portion and the movable portions.

13. An angular velocity sensor according to claim 12, wherein the displacement is caused by the angular velocity applied around an axis perpendicular to a plane on which the movable portions are displaced.

14. An angular velocity sensor comprising:

a substrate;

a plurality of movable portions movably supported on the substrate, including a first movable portion and a second movable portion being point-symmetry arranged with the first movable portion with respect to a predetermined point, the first and second movable portions being oscillated in a circumferential direction centering the predetermined point in the same phase of each other, and being arranged so as to be movable in a radial direction parallel to a surface of the substrate with respect to the predetermined point when angular velocity is generated around the predetermined point on a condition that the first and second movable portions oscillate in the circumferential direction;

a detection portion provided at an outer side of the movable portions, for detecting displacement of the movable portions in the radial direction in accordance with the angular velocity; and

a process circuit for processing signals from the detection portion and for outputting an angular velocity signal due to Corioli'"'"'s force acting on the movable portions in a flat plane parallel to the substrate as a result of oscillation of the movable portions.

15. An angular velocity sensor according to claim 14, wherein the movable portions further includes a third movable portion and a fourth movable portion being point-symmetry arranged with the first movable portion with respect to a predetermined point, the third and fourth movable portions being oscillated in the circumferential direction about the predetermined point in the same phase of each other and in the reverse phase with respect to the phase of the first and the second movable portions.

16. An angular velocity sensor according to claim 14, wherein the detection portion faces the movable portions in the radial direction, and detects changes in capacitance between the detection portion and the movable portions.

17. An angular velocity sensor according to claim 16, wherein the displacement is caused by the angular velocity applied around an axis perpendicular to a plane on which the movable portions are displaced.