OSCILLATING ANGULAR SPEED SENSOR

• US 20100229646A1
• Filed: 03/12/2010
• Published: 09/16/2010
• Est. Priority Date: 03/13/2009
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: HIGUCHI, Hirofumi, Fujii, Tetsuo, Yamanaka, Akitoshi
• Granted Patent: US 8,210,040 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

Abstract

An oscillating angular speed sensor includes a detector, a driving portion, and a separating portion. When an angular speed is generated while the detector is driven to oscillate by the driving portion, Coriolis force is applied to the detector. Therefore, the angular speed is detected based on a capacitance variation in accordance with a variation of an interval between a movable electrode and a fixed electrode of the detector. The separating portion is distanced from the detector and the driving portion, and is configured to separate a first space accommodating the detector and a second space accommodating the driving portion.

Claims

1. An oscillating angular speed sensor comprising:

a detector arranged on a face of a substrate, the detector having

a fixed electrode supported by a part of the substrate, and

a movable electrode to oppose to the fixed electrode so as to be movable relative to the fixed electrode in a movable direction,

a driving portion arranged on the face of the substrate, the driving portion driving the detector to oscillate in a drive direction approximately perpendicular to the movable direction; and

a separating portion fixed on the face of the substrate so as to be distanced from the detector and the driving portion, wherein

the movable electrode is displaced by Coriolis force applied to the detector, when an angular speed is generated while the detector is oscillated, such that the angular speed is detected based on a capacitance variation generated in accordance with a variation of an interval between the movable electrode and the fixed electrode, and

the separating portion is configured to separate a first space accommodating the detector and a second space accommodating the driving portion.

2. The oscillating angular speed sensor according to claim 1, wherein

the detector is located to surround the driving portion,

the separating portion covers the driving portion, and

the separating portion is distanced from the driving portion.

3. The oscillating angular speed sensor according to claim 1, wherein

the driving portion is located to surround the detector,

the separating portion is distanced from the detector, and

the separating portion covers the detector.

4. The oscillating angular speed sensor according to claim 1, wherein

the separating portion includes

a first cap fixed on the face of the substrate so as to surround the detector, and

a second cap fixed on the face of the substrate so as to surround the driving portion,

the first cap covers the detector, and is distanced from the detector, such that the detector is sealed in the first space by the first cap,

the second cap covers the driving portion, and is distance from the driving portion, such that the driving portion is sealed in the second space by the second cap, and

the first space and the second space are separated from each other.

5. The oscillating angular speed sensor according to claim 1, wherein

the separating portion includes

a first cap fixed on the face of the substrate so as to surround the detector, and

a second cap fixed on the substrate so as to cover the first cap and to be distanced from the first cap,

the first cap covers the detector, and is distanced from the detector, such that the detector is sealed in the first space by the first cap,

the second space is defined between the first cap and the second cap,

the first cap has a wiring extending approximately parallel to the movable direction of the movable electrode,

a part of the second cap is made of a magnetic member to generate a magnetic field approximately perpendicular to the face of the substrate,

the driving portion is made of the wiring of the first cap and the magnetic member of the second cap, and

the detector is oscillated in the drive direction by Lorenz force generated in the wiring, when a current flows in the wiring, and when the magnetic field is applied to the wiring.

6. The oscillating angular speed sensor according to claim 1, wherein

the separating portion includes

a first cap fixed on the face of the substrate so as to surround the detector, and

a second cap fixed on the substrate so as to cover the first cap and to be distanced from the first cap,

the first cap covers the detector, and is distanced from the detector, such that the detector is sealed in the first space by the first cap,

the second space is defined between the first cap and the second cap,

a part of the first cap is made of a magnetic member to generate a magnetic field approximately perpendicular to the face of the substrate,

the second cap has a wiring extending approximately parallel to the movable direction of the movable electrode,

the driving portion is made of the magnetic member of the first cap and the wiring of the second cap, and

the detector is oscillated in the drive direction by Lorenz force generated in the wiring, when a current flows in the wiring, and when the magnetic field is applied to the wiring.

7. The oscillating angular speed sensor according to claim 4, wherein

the substrate includes a first board, a second board, and an insulation layer layered between the first board and the second board,

the detector and the driving portion are constructed by the first board, and

the first cap and the second cap are fixed on a face of the first board.

8. The oscillating angular speed sensor according to claim 7, wherein

the first board includes a support board, a semiconductor layer, and a sacrifice layer layered between the support board and the semiconductor layer,

the fixed electrode and the movable electrode are constructed by the semiconductor layer, and

the first cap and the second cap are fixed on a face of the semiconductor layer opposite from the sacrifice layer.

9. The oscillating angular speed sensor according to claim 8, wherein

the first cap and the detector define an oscillator,

the driving portion is located to surround the oscillator,

the driving portion has a driving beam connected to the oscillator,

the driving beam is constructed by only the semiconductor layer of the first board, such that the sacrifice layer, the support board and the insulation layer are eliminated in an area of the driving beam,

the driving beam supports the oscillator to be separated from the second board,

the first cap has a thickest part having a first thickness,

the first thickness is approximately equal to a sum of thicknesses of the support board and the sacrifice layer, and

the oscillator and the driving beam have center of gravity located in the same face approximately parallel to the face of the semiconductor layer.

10. The oscillating angular speed sensor according to claim 8, wherein

the face of the semiconductor layer and a face of the first cap opposing to the semiconductor layer are separated from each other by a first distance, and

the first distance is approximately equal to a second distance defined between the support board and the movable electrode.

11. The oscillating angular speed sensor according to claim 1, wherein

the second space has a pressure lower than a pressure of the first space.