Angular velocity sensor

• US 6,240,780 B1
• Filed: 02/25/1999
• Issued: 06/05/2001
• Est. Priority Date: 03/16/1998
• Status: Expired due to Term

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Negoro, Yosuhiro, Kobayashi, Shinji, Konaka, Yoshihiro, Moriya, Kazufumi
• Primary Examiner(s): Chapman, John E.
• Application Number:
  US09/257,852
• Time in Patent Office: 831 Days
• Field of Search: 735/041.2, 735/041.4, 735/041.5, 735/041.6
• 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

An angular velocity sensor includes a board, a first vibrator, a second vibrator, a vibration generator, a displacement detector and a frequency adjuster. The first vibrator is supported on the board through first supporting beams and arranged so as to be vibrated in the direction of a first axis. The second vibrator is supported on the first vibrator through second supporting beams and arranged so as to be vibrated in the direction of the first axis and in the direction of a second axis at a right angle to the direction of the first axis. The vibration generator cause the first vibrator to vibrate in the direction of the first axis. The displacement detector detects a displacement of the second vibrator in the direction to the second axis when an angular velocity has been applied around a third axis at right angles with the first and second axes. The frequency adjuster adjusts a vibrating side resonance frequency at the time when the first vibrator is vibrated in the direction of the first axis and adjusts a detecting side resonance frequency at the time when the second vibrator is vibrated in the direction of the second axis by an angular velocity applied around the third axis.

Claims

1. An angular velocity sensor comprising:

a board;

a first vibrator supported on the board through first supporting beams and arranged so as to be vibrated in the direction of a first axis;

a second vibrator supported on the first vibrator through second supporting beams and arranged so as to be vibrated in the direction of the first axis by the first vibrator and in the direction of a second axis at a right angle to the direction of the first axis when an angular velocity is applied to the second vibrator around a third axis at right angles to the first and second axes;

a vibration generating means to cause the first vibrator to vibrate in the direction of the first axis;

a displacement detecting means to detect a displacement of the second vibrator in the direction of the second axis when the angular velocity is applied around the third axis and when the vibration generating means causes the first vibrator to vibrate in the direction of the first axis; and

a frequency adjustment means for adjusting a vibrating side resonance frequency when the first vibrator is vibrated in the direction of the first axis by the vibration generating means and adjusting the detecting side resonance frequency when the second vibrator is vibrated in the direction of the second axis by an angular velocity applied around the third axis, the frequency adjustment means including a vibrating side additional electrode formed on an end surface of the first vibrator and a fixed side additional electrode facing the vibrating side additional electrode and formed on a side of the board, the frequency adjustment means applying in the first direction an electrostatic attraction force caused between the vibrating side additional electrode and the fixed side additional electrode.

2. An angular velocity sensor comprising:

a board;

a first vibrator supported on the board through first supporting beams and arranged so as to be vibrated in the direction of a first axis;

a second vibrator supported on the first vibrator through second supporting beams and arranged so as to be vibrated in the direction of the first axis by the first vibrator and in the direction of a second axis at a right angle to the direction of the first axis when an angular velocity is applied to the second vibrator around a third axis at right angles to the first and second axes;

a vibration generating means to cause the first vibrator to vibrate in the direction of the first axis;

a displacement detecting means to detect a displacement of the second vibrator in the direction of the second axis when the angular velocity is applied around the third axis and when the vibration generating means causes the first vibrator to vibrate in the direction of the first axis; and

a frequency adjustment means for adjusting a vibrating side resonance frequency when the first vibrator is vibrated in the direction of the first axis by the vibration generating means and adjusting the detecting side resonance frequency when the second vibrator is vibrated in the direction of the second axis by an angular velocity applied around the third axis, the frequency adjustment means comprising a vibration adding means for adding a force in the direction of the first axis to the first vibrator when the vibration generating means vibrates the first vibrator in the direction of the first axis, the vibration adding means comprising a vibrating side additional electrode formed on an end surface of the first vibrator and a fixed side additional electrode facing the vibrating side additional electrode and formed on a side of the board, the respective facing surfaces of the vibrating side additional electrode and the fixed side additional electrode being saw-toothed.

3. An angular velocity sensor comprising:

a board;

a first vibrator supported on the board through first supporting beams and arranged so as to be vibrated in the direction of a first axis;

a second vibrator supported on the first vibrator through second supporting beams and arranged so as to be vibrated in the direction of the first axis by the first vibrator and in the direction of a second axis at a right angle to the direction of the first axis when an angular velocity is applied to the second vibrator around a third axis at right angles to the first and second axes;

a vibration generating means to cause the first vibrator to vibrate in the direction of the first axis;

a displacement detecting means to detect a displacement of the second vibrator in the direction of the second axis when the angular velocity is applied around the third axis and when the vibration generating means causes the first vibrator to vibrate in the direction of the first axis; and

a frequency adjustment means for adjusting a vibrating side resonance frequency when the first vibrator is vibrated in the direction of the first axis by the vibration generating means and adjusting the detecting side resonance frequency when the second vibrator is vibrated in the direction of the second axis by an angular velocity applied around the third axis, the frequency adjustment means comprising a vibration adding means for adding a force in the direction of the second axis to the second vibrator, the vibration adding means comprising a vibrating side additional electrode formed on an end surface of the second vibrator and a fixed side additional electrode facing the vibrating side additional electrode and formed on a side of the board, the respective facing surfaces of the vibrating side additional electrode and the fixed side additional electrode being saw-toothed.

4. An angular velocity sensor comprising:

a board;

a first vibrator supported on the board through first supporting beams and arranged so as to be vibrated in the direction of a first axis;

a second vibrator supported on the first vibrator through second supporting beams and arranged so as to be vibrated in the direction of the first axis by the first vibrator and in the direction of a second axis at a right angle to the direction of the first axis when an angular velocity is applied to the second vibrator around a third axis at right angles to the first and second axes;

a vibration generating means to cause the first vibrator to vibrate in the direction of the first axis;

a displacement detecting means to detect a displacement of the second vibrator in the direction of the second axis when the angular velocity is applied around the third axis and when the vibration generating means causes the first vibrator to vibrate in the direction of the first axis; and

a frequency adjustment means for adjusting a vibrating side resonance frequency when the first vibrator is vibrated in the direction of the first axis by the vibration generating means and adjusting the detecting side resonance frequency when the second vibrator is vibrated in the direction of the second axis by an angular velocity applied around the third axis, the frequency adjustment means comprising a first vibration adding means for adding a force in the direction of the first axis to the first vibrator when the vibration generating means vibrates the first vibrator in the direction of the first axis and a second vibration adding means for adding a force in the direction of the second axis to the second vibrator, the second vibration adding means comprising a vibrating side additional electrode formed on an end surface of the second vibrator and a fixed side additional electrode facing the vibrating side additional electrode and formed on a side of the board, the respective facing surfaces of the vibrating side additional electrode and the fixed side additional electrode being saw-toothed.

5. An angular velocity sensor comprising:

a board;

a first vibrator structured and arranged to be vibrated in the direction of a first axis with respect to the board;

a second vibrator supported on the first vibrator and structured and arranged so as to be vibrated in the direction of the first axis by the first vibrator and in the direction of a second axis at a right angle to the direction of the first axis when an angular velocity is applied to the second vibrator around a third axis at right angles to the first and second axes;

a vibration generator to cause the first vibrator to vibrate in the direction of the first axis;

a displacement detector to detect a displacement of the second vibrator in the direction of the second axis when the angular velocity is applied around a third axis; and

a frequency adjuster for adjusting a resonant frequency of vibration or a resonant frequency of detection or respective resonant frequencies of vibration and detection, the frequency adjuster including a vibrating side additional electrode formed on an end surface of the second vibrator and a fixed side additional electrode facing the vibrating side additional electrode and formed on a side of the board, the frequency adjuster applying in the second direction an electrostatic attraction force caused between the vibrating side additional electrode and the fixed side additional electrode.

6. An angular velocity sensor comprising:

a first vibrator structured and arranged to be vibrated in the direction of a first axis;

a second vibrator supported on the first vibrator and structured and arranged so as to be vibrated in the direction of the first axis by the first vibrator and in the direction of a second axis at a right angle to the direction of the first axis when an angular velocity is applied to the second vibrator around a third axis at right angles to the first and second axes;

a vibration generator to cause the first vibrator to vibrate in the direction of the first axis;

a displacement detector to detect a displacement of the second vibrator in the direction of the second axis when the angular velocity is applied around a third axis; and

a frequency adjuster for adjusting a resonant frequency of vibration or a resonant frequency of detection or respective resonant frequencies of vibration and detection, the frequency adjuster adds a force in the direction of the first axis to the first vibrator when the first vibrator is vibrated in the direction of the first axis by the vibration generator, the frequency adjustor comprising a vibrating side additional electrode formed on an end surface of the first vibrator and a fixed side additional electrode facing the vibrating side additional electrode and mounted on a support member, the respective facing surfaces of the vibrating side additional electrode and the fixed side additional electrode being saw-toothed.

7. An angular velocity sensor comprising:

a first vibrator structured and arranged to be vibrated in the direction of a first axis;

a second vibrator supported on the first vibrator and structured and arranged so as to be vibrated in the direction of the first axis by the first vibrator and in the direction of a second axis at a right angle to the direction of the first axis when an angular velocity is applied to the second vibrator around a third axis at right angles to the first and second axes;

a vibration generator to cause the first vibrator to vibrate in the direction of the first axis;

a displacement detector to detect a displacement of the second vibrator in the direction of the second axis when the angular velocity is applied around a third axis; and

a frequency adjuster for adjusting a resonant frequency of vibration or a resonant frequency of detection or respective resonant frequencies of vibration and detection, the frequency adjuster adding a force in the direction of the second axis to the second vibrator and comprising a vibrating side additional electrode formed on an end surface of the second vibrator and a fixed side additional electrode facing the vibrating side additional electrode and mounted on a support member, the respective facing surfaces of the vibrating side additional electrode and the fixed side additional electrode being saw-toothed.

8. An angular velocity sensor comprising:

a first vibrator structured and arranged to be vibrated in the direction of a first axis;

a second vibrator supported on the first vibrator and structured and arranged so as to be vibrated in the direction of the first axis by the first vibrator and in the direction of a second axis at a right angle to the direction of the first axis when an angular velocity is applied to the second vibrator around a third axis at right angles to the first and second axes;

a vibration generator to cause the first vibrator to vibrate in the direction of the first axis;

a displacement detector to detect a displacement of the second vibrator in the direction of the second axis when the angular velocity is applied around a third axis; and

a frequency adjuster for adjusting a resonant frequency of vibration or a resonant frequency of detection or respective resonant frequencies of vibration and detection, the frequency adjuster adding a force in the direction of the first axis to the first vibrator when the first vibrator is vibrated in the direction of the first axis by the vibration generator, and adding a force in the direction of the second axis to the second vibrator, the frequency adjuster comprising a vibrating side additional electrode formed on an end surface of the first vibrator and a fixed side additional electrode facing the vibrating side additional electrode and mounted on a support member, the respective facing surfaces of the vibrating side additional electrode and the fixed side additional electrode being saw-toothed.