Acceleration sensor

• US 6,513,382 B2
• Filed: 04/16/2001
• Issued: 02/04/2003
• Est. Priority Date: 11/17/2000
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited, Fujitsu Media Devices Limited (Fujitsu Limited)
• Original Assignee: Fujitsu Limited, Fujitsu Media Devices Limited (Fujitsu Limited)
• Inventors: Ono, Masaaki, Sawada, Katsuhiro, Tanaka, Hiroshi, Yachi, Masanori, Ishikawa, Hiroshi
• Primary Examiner(s): MOLLER, RICHARD ALAN
• Application Number:
  US09/834,958
• Publication Number:
  US 20020059830A1
• Time in Patent Office: 659 Days
• Field of Search: 735/140.1, 735/141.5, 735/141.6, 735/143.4, 310/311, 310/313.A, 310/365
• US Class Current: 73/514.01
• CPC Class Codes: G01P 15/0915 of the shear mode type
• CPC Class Codes: G01P 15/097 by vibratory elements
• CPC Class Codes: G01P 15/18 in two or more dimensions

Abstract

A small-sized, high detection sensitivity and high performance acceleration sensor having directional or non-directional sensitivity is disclosed. The acceleration sensor is provided with a vibrator having uni-directional polarization and a weight connected to the vibrator. The weight is supported at the position different from the center of gravity of the total body of the vibrator and the weight itself. The vibrator is disposed so that its direction of polarization axis is either consistent or inconsistent with an axis of the torsion of the vibrator.

Claims

1. An acceleration sensor comprising:

a vibrator having unidirectional polarization;

a weight connected to said vibrator;

the weight being supported at a position deviating from the center of gravity of the entity of the vibrator and the weight; and

a plurality of separate detection electrodes formed on one side of the vibrator.

2. The acceleration sensor according to claim 1,

wherein one electrode out of said plurality of separate detection electrodes has different area ration from the other electrodes.

3. The acceleration sensor according to claim 1,

wherein the vibrator and the weight are disposed in a different center line position of line symmetry in a width direction.

4. The acceleration sensor according to claim 1,

wherein the center of gravity of said weight is positioned deviating from a center line of line symmetry in a width direction of the vibrator.

5. The acceleration sensor according to claim 1,

wherein the vibrator is a piezoelectric vibrator formed of either a piezoelectric single crystal or a piezoelectric polycrystal.

6. The acceleration sensor according to claim 1,

wherein said plurality of separate detection electrodes of the vibrator is formed through etching, dicing or a similar process.

7. The acceleration sensor according to claim 1,

wherein the vibrator comprises two separate detection electrodes respectively formed in parallel with a torsion direction of the vibrator.

8. The acceleration sensor according to claim 1,

wherein the vibrator comprises two separate detection electrodes respectively formed perpendicularly to a torsion direction of the vibrator.

9. An acceleration sensor comprising:

a vibrator having unidirectional polarization;

a weight connected to said vibrator, the weight being supported at a position deviating from the center of gravity of the entity of the vibrator and the weight; and

a plurality of separate electrodes formed on one side of the vibrator, at least one out of which is a detection electrode.