INERTIAL SENSOR

• US 20100037691A1
• Filed: 08/12/2008
• Published: 02/18/2010
• Est. Priority Date: 08/12/2008
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Fukuda, Hiroshi, Jeong, Heewon
• Granted Patent: US 8,250,916 B2
• Time in Patent Office: Days
• US Class Current: 73/504.120
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 15/097 by vibratory elements
• CPC Class Codes: G01P 15/125 by capacitive pick-up

Abstract

One inertial sensor detects an acceleration in a driving direction as well as an angular rate about one axis and an acceleration in a detecting direction at the same time. A driving-direction acceleration detecting unit is provided to members vibrating in mass members on the left and right via an elastic body. In this manner, when an acceleration is applied in the driving direction, the mass members on the left and right normally vibrated with a same amplitude and in opposite phases have displacement amounts in a same phase, and the driving-direction acceleration detecting unit detects the displacement amounts in the same phase as a capacitance change, thereby detecting the acceleration in the driving direction.

Claims

1. An inertial sensor comprising:

(a) a basement layer having a main surface; and

(b) a first sensor unit and a second sensor unit arranged along a first direction on the main surface of the basement layer, wherein

each of the first sensor unit and the second sensor unit includes;

(b1) a drive frame that is vibrated in a driving direction being the first direction; and

(b2) a driving unit that vibrates the drive frame in the driving direction, wherein

the drive frame of the first sensor unit and the drive frame of the second sensor unit are vibrated in opposite phases with each other; and

the inertial sensor comprising

(c) a driving-direction acceleration detecting unit that is connected to the drive frame of the first sensor unit and the drive frame of the second sensor unit via an elastic body and detects an acceleration in the driving direction.

2. The inertial sensor according to claim 1, wherein

the driving-direction acceleration detecting unit detects the acceleration in the driving direction by detecting displacement amounts in a same phase in the driving direction of the drive frame of the first sensor unit and the drive frame of the second sensor unit.

3. The inertial sensor according to claim 2, wherein

the driving-direction acceleration detecting unit is formed by a capacitive element arranged in a comb-teeth shape and detects the acceleration in the driving direction based on a capacitance change of the capacitive element.

4. The inertial sensor according to claim 1, wherein

the driving unit is formed by a capacitive element arranged in a comb-teeth shape and vibrates the drive frame in the driving direction based on a electrostatic attractive force applied to the capacitive element.

5. The inertial sensor according to claim 1, wherein

a plurality of the driving-direction acceleration detecting units are formed.

6. The inertial sensor according to claim 1, wherein

the elastic body connecting the drive frame of the first sensor unit and the drive frame of the second sensor unit is fixed to the basement layer.

7. The inertial sensor according to claim 1, wherein

the elastic body connecting the drive frame of the first sensor unit and the drive frame of the second sensor unit is not fixed to the basement layer.

8. The inertial sensor according to claim 1, wherein

each of the first sensor unit and the second sensor unit comprises:

a Coriolis frame that is connected to the drive frame and vibrated in the driving direction in a same phase with the vibration of the drive frame, and vibrated in a detecting direction intersecting the driving direction by Coriolis force; and

a detecting unit that detects a displacement amount of the Coriolis frame in the detecting direction based on the vibration of the Coriolis frame in the detecting direction.

9. The inertial sensor according to claim 8, wherein

the detecting unit is formed by a capacitive element arranged in a comb-teeth shape and detects the displacement amount in the detecting direction based on a capacitance change of the capacitive element.

10. The inertial sensor according to claim 8, wherein

an angular rate and the acceleration in the detecting direction are detected based on the displacement amount in the detecting direction detected by the detecting unit of the first sensor unit and the displacement amount in the detecting direction detected by the detecting unit of the second sensor unit.

11. The inertial sensor according to claim 1, wherein

each of the first sensor unit and the second sensor unit comprises:

a Coriolis frame that is connected to the drive frame and vibrated in the driving direction in a same phase with the vibration of the drive frame, and vibrated in a detecting direction intersecting the driving direction by Coriolis frame;

a detection frame that is connected to the Coriolis frame and vibrated in the detecting direction in a same phase with the vibration in the detecting direction of the Coriolis force; and

a detecting unit that detects a displacement amount of the detection frame in the detecting direction based on the vibration in the detecting direction.

12. The inertial sensor according to claim 11, wherein

the detecting unit is formed by a capacitive element arranged in a comb-teeth shape and detects the displacement amount in the detecting direction based on a capacitance change of the capacitive element.

13. The inertial sensor according to claim 11, wherein

an angular rate and the acceleration in the detecting direction are detected based on the displacement amount in the detecting direction detected by the detecting unit of the first sensor unit and the displacement amount in the detecting direction detected by the detecting unit of the second sensor unit.

14. The inertial sensor according to claim 1, wherein

the basement layer is an SOI substrate.

15. The inertial sensor according to claim 1, wherein

the first sensor unit and the second sensor unit are formed of conductive silicon, conductive poly-silicon, or a metal.

16. An inertial sensor comprising:

(a) a basement layer having a main surface; and

(b) a first sensor unit and a second sensor unit arranged along a first direction on the main surface of the basement layer, wherein

each of the first sensor unit and the second sensor unit includes;

(b1) a drive frame that is vibrated in a driving direction being the first direction;

(b2) a driving unit that vibrates the drive frame in the driving direction; and

(b3) a structure that is vibrated in the driving direction, wherein

the drive frame of the first sensor unit and the drive frame of the second sensor unit are vibrated in opposite phases with each other, and a structure of the first sensor unit and a structure of the second sensor unit are vibrated in opposite phases with each other; and

the inertial sensor comprising

(c) a driving-direction acceleration detecting unit that is connected to the structure of the first sensor unit and the structure of the second sensor unit via an elastic body and detects an acceleration in the driving direction.

17. The inertial sensor according to claim 16, wherein

the driving-direction acceleration detecting unit detects the acceleration in the driving direction by detecting displacement amounts in a same phase in the driving direction of the structure of the first sensor unit and the structure of the second sensor unit.

18. The inertial sensor according to claim 17, wherein

the driving-direction acceleration detecting unit is formed by a capacitive element arranged in a comb-teeth shape and detects the acceleration in the driving direction based on a capacitance change of the capacitive element.

19. An inertial sensor comprising:

(a) a basement layer having a main surface; and

(b) a first sensor unit and a second sensor unit arranged along a first direction on the main surface of the basement layer, wherein

each of the first sensor unit and the second sensor unit includes;

(b1) a drive frame that is vibrated in a driving direction being the first direction; and

(b2) a driving unit that vibrates the drive frame in the driving direction, wherein

the drive frame of the first sensor unit and the drive frame of the second sensor unit are vibrated in opposite phases with each other; and

the inertial sensor comprising

(c) a driving-direction acceleration detecting unit that is connected to a joint of the elastic body and detects an acceleration in the driving direction.

20. The inertial sensor according to claim 19, wherein

the driving-direction acceleration detecting unit detects the acceleration in the driving direction by detecting that a position of the joint of the elastic body is displaced in the driving direction.

21. The inertial sensor according to claim 20, wherein

the driving-direction acceleration detecting unit is formed by a capacitive element arranged in a comb-teeth shape and detects the acceleration in the driving direction based on a capacitance change of the capacitive element.