Capacitive type dynamic quantity sensor

• US 20030154789A1
• Filed: 11/12/2002
• Published: 08/21/2003
• Est. Priority Date: 02/19/2002
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Sakai, Minekazu
• Granted Patent: US 6,848,309 B2
• Time in Patent Office: Days
• US Class Current: 73/514.32
• 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

In a capacitive type dynamic quantity sensor, a width of a beam in a beam portion extending in a direction that is perpendicular to a predetermined deformation direction and a gap disposed between a movable electrode and the fixed electrode in the predetermined deformation direction are approximately identical. Accordingly, manufacturing error is prevented from affecting the sensitivity of the capacitive type dynamic quantity sensor. For example, a manufacturing tolerance error of ±2.5% is allowed as a result of designing the width of the beam and the gap to be identical in length.

Claims

1. A capacitive type dynamic quantity sensor comprising:

a beam portion having a beam for deforming in a predetermined deformation direction based on physical force application;

a movable electrode formed integrally with the beam portion to move therewith and extending in a direction perpendicular to the predetermined deformation direction; and

a fixed electrode facing the movable electrode and being separated therefrom in the predetermined deformation direction by a predetermined gap;

wherein a width of the beam extending in the direction perpendicular to the predetermined deformation direction and the gap are approximately identical.

2. The capacitive type dynamic quantity sensor of claim 1, wherein the beam of the beam portion includes two beams, both of which extend in a parallel direction and join with each other at end portions thereof, the width of each of the beams being approximately the same as a width of the gap.

3. The capacitive type dynamic quantity sensor of claim 1, wherein the width of the beam and the gap are defined so that one may be shifted by ±

2.5% from another.

4. The capacitive type dynamic quantity sensor of claim 1, wherein the capacitive type dynamic quantity sensor is adapted for use in one of a one of vehicle acceleration sensor for airbag control, a gyro sensor for airbag control, for ABS control and for side skid control.

5. The capacitive type dynamic quantity sensor of claim 1, further comprising:

a plumb portion formed integrally with the movable electrode and the beam portion,

wherein the movable electrode includes comb-shaped electrodes located at both sides of the plumb portion; and

the fixed electrode includes comb-shaped first and second fixed electrodes extending in parallel with, and opposed to respective ones of the comb-shaped electrodes of the movable electrode so as to define the predetermined gap therebetween.

6. A method of manufacturing a capacitive type dynamic quantity sensor, wherein the capacitive type dynamic quantity sensor has a beam portion with a beam for deforming in a predetermined deformation direction based on physical force application, a movable electrode formed integrally with the beam portion to move therewith and extending in a direction perpendicular to the predetermined deformation direction, and a fixed electrode facing and being separated from the movable electrode, comprising:

forming a trench in a substrate to form the beam portion, the movable electrode and the fixed electrode simultaneously, wherein the forming of the trench forms the beam so as to have a width extending in the direction perpendicular to the predetermined deformation direction, and the gap disposed between the movable electrode and the fixed electrode so as to have a width in the predetermined deformation direction that is approximately identical to the beam width.

7. The method of claim 6, wherein the forming the trench includes forming the trench by etching the substrate.

8. The method of claim 6, wherein the forming the trench defines the width of the beam and the gap so that one of which may be shifted by ±

2.5% from another.

9. A method of manufacturing a capacitive type dynamic quantity sensor comprising:

forming a trench in a substrate to form a beam portion, a movable electrode and a fixed electrode simultaneously, wherein the forming of the trench forms the beam so as to have a width extending in a direction perpendicular to a predetermined deformation direction, and a gap disposed between the movable electrode and the fixed electrode so as to have a width in the predetermined deformation direction that is approximately identical to the beam width.