Inertia force sensor

• US 6,736,008 B2
• Filed: 11/21/2002
• Issued: 05/18/2004
• Est. Priority Date: 05/24/2002
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Yoshida, Yukihisa, Tsutsumi, Kazuhiko, Kumagai, Munehito
• Primary Examiner(s): Kwok, Helen C.
• Application Number:
  US10/300,751
• Publication Number:
  US 20030217597A1
• Time in Patent Office: 544 Days
• Field of Search: 735/041.4, 735/040.4, 735/141.6, 735/142.9, 735/740.1, 735/143.2, 735/041.5, 735/040.2, 735/143.8, 738/623.82
• US Class Current: 73/504.14
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type

Abstract

An inertia force sensor with a damper. The damper includes a cantilever for a movable part disposed in a movable electrode protruding therefrom, and a cantilever for a fixed part disposed in a support portion for the movable part or a support portion for the fixed part and protruding therefrom. The damper allows the cantilever for the movable part and the cantilever for the fixed part to contact each other before the movable electrode contacts the support portion for the movable part and the support portion for the fixed part. As a result, it is possible to prevent a stopper from being damaged and to improve the reliability of the sensor.

Claims

1. An inertia sensor comprising:

insulating substrates; and

a silicon structure that is bonded between the insulating substrate with a clearance space therebetween, said silicon structure having

a movable portion and a fixed portion, the movable portion having a movable electrode displaceable in a direction of an inertial force applied to the sensor,

first and second beam structures for the movable portion, connected to respective ends of the movable electrode and supporting the movable dec ode opposite the clearance space, and

a pair of support portions for the movable portion that support the beam structures for the movable portion and are bonded to the insulating substrates, wherein the fixed portion has a fixed electrode opposing the movable electrode and a support portion for the fixed portion that supports the fixed electrode and is bond to the insulating substrates,

stoppers that restrict displacement of the movable electrode on four outer corners of the first and second beam structures for the movable portion so the movable electrode is brought into contact with the support portions for the movable portion and the support portion for the fixed portion, and

a damper, including a cantilever for the movable portion, provided on the movable electrode, protruding, therefrom, and extending opposite the clearance space, and a cantilever for the fixed portion provided on the support portions for the movable portion or the support portion for the fixed portion, protruding therefrom, and extending opposite the clearance space, disposed near each of the stoppers so that the cantilever for the movable portion and the cantilever for the fixed portion make contact with each other before the movable electrode contacts the support portions for the movable portion and the support portion for the fixed portion.

2. The inertia sensor according to claim 1, wherein the damper is disposed near the stoppers.

3. The inertia sensor according to claim 1, wherein the cantilever for the movable portion and the cantilever for the fixed portion are disposed substantially at right angles to the direction of movable electrode displacement.

4. The inertia sensor according to claim 1, wherein a distance between the cantilever for the movable portion and the cantilever for the fixed portion is smaller than a distance between the movable electrode and the support portions of the movable portion, and smaller than a distance between the movable electrode and the support portions of the fixed portion in the stoppers.

5. The inertia sensor according to claim 1, wherein

the movable electrode has a comb-shaped electrode for the movable portion that includes a plurality of cantilever electrodes disposed on opposite sides of the movable portion in a longitudinal direction and extending opposite the clearance space, and the fixed electrode has a comb-shaped electrode for the fixed portion including a plurality of cantilever electrodes that extend opposite the clearance space,

the plurality of cantilever electrodes of the comb-shaped electrode for the movable portion and the comb-shaped electrode for the fixed portion are opposite e ch other across a gap, and

at least a pair of opposing cantilever electrodes of the comb-shape electrode for the movable portion and the comb-shaped electrode for the fixed portion are ore rigid than others of the cantilever electrodes, thereby forming a damper portion.