Vibrator and vibrating gyroscope

• US 9,383,205 B2
• Filed: 01/07/2014
• Issued: 07/05/2016
• Est. Priority Date: 08/01/2011
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Fujimoto, Katsumi, Yoneda, Toshimaro, Hada, Takuo, Horiuchi, Hideya
• Primary Examiner(s): Kwok, Helen
• Application Number:
  US14/148,964
• Publication Number:
  US 20140116188A1
• Time in Patent Office: 910 Days
• Field of Search: 735/041.2, 735/041.4, 735/040.4, 735/041.5, 735/142.9, 735/143.6, 735/143.8
• US Class Current: 1/1
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01C 19/5607 using vibrating tuning forks double-ended tuning forks using planar vibrating masses suspended at opposite ends G01C19/5719
• CPC Class Codes: G01C 19/5621 the devices involving a micromechanical structure
• CPC Class Codes: H10N 30/20 with electrical input and mechanical output, e.g. functioning as actuators or vibrators
• CPC Class Codes: Y10T 74/12 Gyroscopes
• CPC Class Codes: Y10T 74/18856 Oscillating to oscillating

Abstract

A vibrator includes first and second circular or substantially circular arc-shaped beam portions, a base end-side weight portion, and a base end-side weight portion joining portion. The end portions of the first and second circular or substantially circular arc-shaped beam portions in an X-axis positive direction face each other across a distance in a Y-axis direction, and the end portions thereof in an X-axis negative direction are joined to each other. The base end-side weight portion is disposed between the first and second circular or substantially circular arc-shaped beam portions. The base end-side weight portion joining portion extends from a joining portion between the first circular or substantially circular arc-shaped beam portion and the second circular or substantially circular arc-shaped beam portion in the X-axis positive direction, and joined to the base end-side weight portion.

Claims

1. A vibrator comprising:

a first circular or substantially circular arc-shaped beam portion and a second circular or substantially circular arc-shaped beam portion in which end portions on one side of a first axis direction face each other across a distance in a second axis direction perpendicular or substantially perpendicular to the first axis direction and end portions on the other side of the first axis direction are joined to each other;

a base end-side weight portion disposed between the first circular or substantially circular arc-shaped beam portion and the second circular or substantially circular arc-shaped beam portion;

a base end-side weight portion joining portion extending from a joining portion between the first circular or substantially circular arc-shaped beam portion and the second circular or substantially circular arc-shaped beam portion in the first axis direction, and joined to the base end-side weight portion;

a first leading end-side weight portion joined to the end portion of the first circular or substantially circular arc-shaped beam portion on the one side of the first axis direction; and

a second leading end-side weight portion joined to the end portion of the second circular or substantially circular arc-shaped beam portion on the one side of the first axis direction.

2. The vibrator according to claim 1, further comprising:

a supporting-portion joining portion extending from the joining portion between the first circular or substantially circular arc-shaped beam portion and the second circular or substantially circular arc-shaped beam portion in a direction opposite to the base end-side weight portion joining portion; and

a supporting portion joined to the supporting-portion joining portion.

3. The vibrator according to claim 2, wherein the supporting portion surrounds the first circular or substantially circular arc-shaped beam portion and the second circular or substantially circular arc-shaped beam portion.

4. The vibrator according to claim 3, further comprising a leading end-side supporting portion extending, in the first axis direction, from an end portion of the base end-side weight portion in the first axis direction, and joined to the supporting portion.

5. The vibrator according to claim 3, wherein the supporting portion is configured so that an inner circumference follows the first circular or substantially circular arc-shaped beam portion and the second circular or substantially circular arc-shaped beam portion.

6. The vibrator according to claim 2, wherein a dimension of the supporting portion in a third axis direction perpendicular or substantially perpendicular to the first axis direction and the second axis direction is larger than the first circular or substantially circular arc-shaped beam portion and the second circular or substantially circular arc-shaped beam portion.

7. A vibrating gyroscope comprising:

the vibrator according to claim 1;

a driving portion configured to drive the vibrator so that the vibrator vibrates in an in-plane vibration mode in which a distance between the end portions of the first circular or substantially circular arc-shaped beam portion and the second circular or substantially circular arc-shaped beam portion on the one side of the first axis direction changes; and

a detecting portion configured to detect a vibration of an out-of-plane vibration mode in which the first circular or substantially circular arc-shaped beam portion and the second circular or substantially circular arc-shaped beam portion alternately bend in a third axis direction due to a Coriolis force applied to the vibrator by an angular velocity around a first axis, the vibrator vibrating in the in-plane vibration mode.

8. The vibrating gyroscope according to claim 7, wherein

the vibrator includes a silicon substrate;

and

the driving portion and the detecting portion include a piezoelectric body film, a ground electrode, a driving electrode or a detection electrode.

9. The vibrating gyroscope according to claim 8, wherein the piezoelectric body film, the ground electrode, the driving electrode, and the detection electrode are provided on only one surface of the vibrator.

10. The vibrating gyroscope according to claim 9, wherein

the driving portion and the detecting portion include a floating electrode;

and

the driving electrode or the detection electrode faces the floating electrode across the piezoelectric body film.

11. The vibrating gyroscope according to claim 9, wherein the driving electrode includes a first driving electrode facing the ground electrode across the piezoelectric body film, and a second driving electrode that faces the ground electrode across the piezoelectric body film and is adjacent to the first driving electrode.

12. The vibrator according to claim 1, wherein the base end-side weight portion defines a supporting portion.

13. The vibrator according to claim 1, further comprising a pad used for an external connection and provided in the base end-side weight portion, detection electrodes, and a ground electrode.

14. The vibrator according to claim 2, wherein the supporting portion includes a rectangular or substantially rectangular frame body including a rectangular or substantially rectangular aperture.

15. The vibrator according to claim 14, wherein the rectangular or substantially rectangular frame body surrounds the first and second circular or substantially circular arc-shaped beam portions.

16. The vibrator according to claim 2, wherein the supporting portion includes a rectangular or substantially rectangular frame body including a circular or substantially circular aperture.

17. The vibrator according to claim 16, wherein a dimension of the supporting portion in a Z-axis direction is larger than the first and second circular or substantially circular arc-shaped beam portions.

18. The vibrator according to claim 1, further comprising first and second leading end-side weight portions including a slit provided therein.

19. The vibrating gyroscope according to claim 7, wherein the driving portion and the detecting portion are defined by one of an electromechanical conversion element and an electrostatic capacitance element.