Angular rate sensor

• US 6,494,094 B1
• Filed: 05/01/2000
• Issued: 12/17/2002
• Est. Priority Date: 11/01/1999
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Fujita, Hiroyuki, Konno, Nobuaki, Tsugai, Masahiro
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US09/562,288
• Time in Patent Office: 960 Days
• Field of Search: 735/040.2, 735/040.3, 735/040.4, 735/040.8, 735/040.9, 735/041.2, 735/143.2, 310/329
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis

Abstract

A conventional angular rate sensor has a problem that the displacement amplitude of a drive gimbal frame is limited due to the Pulled-in phenomenon where the drive gimbal frame is attached to drive electrodes, thereby decreasing its sensor sensitivity. In an angular rate sensor, a drive frame and a driven frame are separately provided. A bending oscillation of the drive frame is transmitted to the driven frame through link beams, causing the rotational oscillation of the driven frame. The displacement amplitude of a rotational oscillation of the driven frame is not limited to provide high sensor sensitivity.

Claims

1. An angular rate sensor comprising:

a substrate;

an inertial mass;

a driven frame surrounding the inertial mass;

inertial mass torsion beams connecting the inertial mass with the driven frame and rotatably supporting the inertial mass at two opposed positions;

driven frame torsion beams connected to and rotatably supporting the driven frame at two opposed positions;

a drive frame surrounding a half circumference of the driven frame with reference to a line extending along torsion axes of the driven frame torsion beams and including

an anchor portion connecting the drive frame to the substrate and

connecting portions transverse to and flexibly connecting the driven frame torsion beams to the anchor portion;

driving force generation means for producing a driving force causing bending oscillation of the drive frame in an out-of-plane direction;

link beams connecting the driven frame to the drive frame at two opposite positions proximate positions at which the driven frame torsion beams are connected to the driven frame; and

detection means for detecting displacement amplitude of a rotational oscillation of the inertial mass.

3. The angular rate sensor according to claim 1, further comprising monitor means for monitoring displacement amplitude of a rotational oscillation of the driven frame.

5. The angular rate sensor according to claim 1, wherein

a mass center of the inertial mass is positioned on the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second surfaces of the driven frame; and

torsion axes of the inertial mass torsion beams are perpendicular to the torsion axes of the driven frame torsion beams.

7. The angular rate sensor according to claim 1, wherein

a mass center of the inertial mass is shifted from the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second surfaces of the driven frame;

and

torsion axes of the inertial mass torsion beams are perpendicular to the torsion axes of the driven frame torsion beams.

9. The angular rate sensor according to claim 1, wherein

a mass center of the inertial mass is shifted from the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second surfaces of the driven frame;

and

torsion axes of the inertial mass torsion beams are parallel to the torsion axes of the driven frame torsion beams.

11. The angular rate sensor angular rate sensor according to claim 1, wherein

the inertial mass and the inertial mass torsion beams include at least two of:

a first inertial mass having a mass center positioned on the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second surfaces of the driven frame, and first inertial mass torsion beams connecting the first inertial mass to the driven frame, torsion axes of the first inertial mass torsion beams being perpendicular to the torsion axes of the driven frame torsion beams;

a second inertial mass having a mass center shifted from the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second bottom surfaces of the driven frame, and second inertial mass torsion beams connecting the second inertial mass to the driven frame, torsion axes of the second inertial mass torsion beams being perpendicular to the torsion axes of the driven frame torsion beams; and

a third inertial mass having a mass center shifted from the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second surfaces of the driven frame, and third inertial mass torsion beams connecting the third inertial mass to the driven frame, torsion axes of the third inertial mass torsion beams being parallel to the torsion axes of the driven frame torsion beams; and

the angular rate sensor comprises at least two rotational angular rate detection parts of;

a first rotational angular rate detection part including the first inertial mass and the first inertial mass torsion beams;

a second rotational angular rate detection part including the second inertial mass and the second inertial mass torsion beams; and

a third rotational angular rate detection part including the third inertial mass and the third inertial mass torsion beams.

13. The angular rate sensor according to claim 1, wherein

the inertial mass includes first and second inertial masses having mass centers symmetrically placed about the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second surfaces of the driven frame;

and

the inertial mass torsion beams include first inertial mass torsion beams connecting the first inertial mass to the driven frame and second inertial mass torsion beams connecting the second inertial mass to the driven frame, torsion axes of the first and second inertial mass torsion beams being parallel to each other.

15. The angular rate sensor according to claim 1, wherein the drive frame includes a first drive frame surrounding a first half circumference of the driven frame with reference to the line extending along the torsion axes of the driven frame torsion beams, and a second drive frame surrounding a second half circumference of the driven frame.

17. The angular rate sensor according to claim 1, wherein the driving force generation means comprises a piezoelectric element on the drive frame, an electrode located opposite the drive frame, or a piezoresistor in the drive frame.

18. The angular rate sensor according to claim 1, wherein the detection means comprises piezoresistors in the inertial mass torsion beams or an electrode located opposite the driven frame.

19. The angular rate sensor according to claim 3, wherein the monitor means comprises a piezoelectric element on the drive frame, an electrode located opposite the drive frames, or piezoresistors in the driven frame torsion beams.

2. An angular rate sensor comprising:

a substrate;

an inertial mass;

a driven frame surrounding the inertial mass;

inertial mass torsion beams connecting the inertial mass with the driven frame and rotatably supporting the inertial mass at two opposed positions;

driven frame torsion beams connected to and rotatably supporting the driven frame at two opposed positions;

a drive frame surrounding a half circumference of the driven frame with reference to a line extending along torsion axes of the driven frame torsion beams and including

an anchor portion connecting the drive frame to the substrate and

connecting portions transverse to and flexibly connecting the driven frame torsion beams to the anchor portion;

driving force generation means for producing a driving force causing bending oscillation of the drive frame in an out-of-plane direction; and

detection means for detecting displacement amplitude of a rotational oscillation of the inertial mass, wherein a center of gravity of the driven frame is located on a side of the line extending along the torsion axes of the driven frame torsion beams opposite from the driving force generation means.

4. The angular rate sensor according to claim 2, further comprising monitor means for monitoring displacement amplitude of a rotational oscillation of the driven frame.

6. The angular rate sensor according to claim 2, wherein

a mass center of the inertial mass is positioned on the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second surfaces of the driven frame; and

torsion axes of the inertial mass torsion beams are perpendicular to the torsion axes of the driven frame torsion beams.

8. The angular rate sensor according to claim 2, wherein

a mass center of the inertial mass is shifted from the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second surfaces of the driven frame;

and

torsion axes of the inertial mass torsion beams are perpendicular to the torsion axes of the driven frame torsion beams.

10. The angular rate sensor according to claim 2, wherein

a mass center of the inertial mass is shifted from the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second surfaces of the driven frame;

and

torsion axes of the inertial mass torsion beams are parallel to the torsion axes of the driven frame torsion beams.

12. The angular rate sensor angular rate sensor according to claim 2, wherein

the inertial mass and the inertial mass torsion beams include at least two of:

a first inertial mass having a mass center positioned on the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second surfaces of the driven frame, and first inertial mass torsion beams connecting the first inertial mass to the driven frame, torsion axes of the first inertial mass torsion beams being perpendicular to the torsion axes of the driven frame torsion beams;

a second inertial mass having a mass center shifted from the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second surfaces of the driven frame, and second inertial mass torsion beams connecting the second inertial mass to the driven frame, torsion axes of the second inertial mass torsion beams being perpendicular to the torsion axes of the driven frame torsion beams; and

a third inertial mass having a mass center shifted from the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second surfaces of the driven frame, and third inertial mass torsion beams connecting the third inertial mass to the driven frame, torsion axes of the third inertial mass torsion beams being parallel to the torsion axes of the driven frame torsion beams; and

the angular rate sensor comprises at least two rotational angular rate detection parts of;

a first rotational angular rate detection part including the first inertial mass and the first inertial mass torsion beams;

a second rotational angular rate detection part including the second inertial mass and the second inertial mass torsion beams; and

a third rotational angular rate detection part including the third inertial mass and the third inertial mass torsion beams.

14. The angular rate sensor according to claim 2, wherein

the inertial mass includes first and second inertial masses having mass centers symmetrically placed about the line extending along the torsion axes of the driven frame torsion beams, and positioned opposite one of the first and second surfaces of the driven frame;

and

the inertial mass torsion beams include first inertial mass torsion beams connecting the first inertial mass to the driven frame and second inertial mass torsion beams connecting the second inertial mass to the driven frame, torsion axes of the first and second inertial mass torsion beams being parallel to each other.

16. The angular rate sensor according to claim 2, wherein the drive frame includes a first drive frame surrounding a first half circumference of the driven frame with reference to line extending along the torsion axes of the driven frame torsion beams and a second drive frame surrounding a second half circumference of the driven frame.