Angular velocity sensor

• US 6,865,943 B2
• Filed: 06/20/2001
• Issued: 03/15/2005
• Est. Priority Date: 12/29/1994
• Status: Expired due to Fees

• Current Assignee: Wacoh Company
• Original Assignee: Kazuhiro Okada
• Inventors: Okada, Kazuhiro
• Primary Examiner(s): Kwok, Helen C.
• Application Number:
  US09/885,620
• Publication Number:
  US 20020040602A1
• Time in Patent Office: 1,364 Days
• Field of Search: 735/041.2, 735/040.2, 735/040.3, 735/040.4, 735/041.3, 735/041.4, 735/041.5, 735/143.2, 735/143.4, 738/620.42, 738/620.43
• 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
• CPC Class Codes: G01P 15/0907 of the compression mode type
• CPC Class Codes: G01P 15/0922 of the bending or flexing mode type
• CPC Class Codes: G01P 15/11 by inductive pick-up
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/084 the mass being suspended at more than one of its sides, e.g. membrane-type suspension, so as to permit multi-axis movement of the mass

Abstract

An angular velocity sensor for detecting an angular velocity component includes an oscillator having mass, a sensor casing for accommodating the oscillator therewithin, a flexible member for connecting the oscillator to the sensor casing so that the oscillator can be moved with respect to the sensor casing, and capacitance elements including a first electrode provided on a surface of the oscillator and a second electrode provided on a surface of a fixed member fixed to the sensor casing.

Claims

1. An angular velocity sensor for detecting an angular velocity component comprising:

an oscillator having mass;

a sensor casing for accommodating the oscillator therewithin;

a flexible member for connecting the oscillator to the sensor casing so that the oscillator can be moved with respect to the sensor casing;

capacitance elements including a first electrode provided on a surface of the oscillator and a second electrode provided on a surface of a fixed member fixed to the sensor casing; and

an excitation element for oscillating the oscillator.

2. An angular velocity sensor for detecting an angular velocity component about a Z-axis in an XYZ three-dimensional coordinate system, the sensor comprising:

an oscillator having mass;

a sensor casing for accommodating the oscillator therewithin;

a flexible member for connecting the oscillator to the sensor casing so that the oscillator can be moved with respect to the sensor casing with at least a degree of freedom along an XY-plane in the coordinate system;

excitation capacitance elements for oscillating the oscillator in the X-axis direction based on Coulomb force, said excitation capacitance elements including an electrode provided on a surface of the oscillator and an electrode provided on a surface of a fixed member fixed to the sensor casing; and

detection capacitance elements for detecting a displacement of the oscillator in a Y-axis direction, said detection capacitance elements including an electrode provided on a surface of the oscillator and an electrode provided on a surface of the fixed member so that an angular velocity component about the Z-axis can be obtained based on the detected displacement.

3. An angular velocity sensor for detecting an angular velocity component about a Z-axis in an XYZ three-dimensional coordinate system, the sensor comprising:

an oscillator having mass;

a sensor casing for accommodating the oscillator therewithin;

a flexible member for connecting the oscillator to the sensor casing so that the oscillator can be moved with respect to the sensor casing with at least a degree of freedom along an XY-plane in the coordinate system;

excitation capacitance elements and detection capacitance elements, each including a first electrode provided on a surface of the oscillator and a second electrode provided on a surface of a fixed member fixed to the sensor casing;

a voltage supplying circuit to apply an a. c. signal to the excitation capacitance elements so that the oscillator is oscillated in the X-axis direction based on Coulomb force; and

a capacitance detecting circuit to detect a capacitance value of the detection capacitance elements so that a displacement of the oscillator in a Y-axis direction is detected and an angular velocity component about the Z-axis can be obtained based on the detected displacement.

4. An angular velocity sensor according to claim 3, wherein the oscillator and the flexible member are made of silicon.

5. An angular velocity sensor according to claim 4, wherein the oscillator is made of a silicon substrate.