Capacitance type accelerometer for air bag system
First Claim
1. A capacitance-accelerometer, comprising:
- a fixed electrode; and
a movable electrode being supported by a cantilever at a portion adjacent to said fixed electrode having a gap thereinbetween;
wherein grooves for reducing air damping are provided on a surface of said movable electrode, andsaid grooves are so arranged that electrode surface areas divided by said grooves are symmetrical with respect to a symmetrical axis parallel to said cantilever.
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Accused Products
Abstract
In a capacitance type accelerometer used for an air bag system etc., a plurality of grooves crossing each other are provided on the surface of a movable electrode which is arranged to face a fixed electrode at a portion having a gap thereinbetween, and end portions of each groove open to an outside space at the portion between the movable electrode and the fixed electrode. The grooves can be provided on surface of the fixed electrodes. Ventilation between inside and outside of the facing portion is improved by opening of the grooves to outside space, and air damping which is caused at operation of the movable electrode at the gap between the electrodes is reduced, and, consequently, response speed of the movable electrode is increased.
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Citations
11 Claims
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1. A capacitance-accelerometer, comprising:
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a fixed electrode; and a movable electrode being supported by a cantilever at a portion adjacent to said fixed electrode having a gap thereinbetween; wherein grooves for reducing air damping are provided on a surface of said movable electrode, and said grooves are so arranged that electrode surface areas divided by said grooves are symmetrical with respect to a symmetrical axis parallel to said cantilever. - View Dependent Claims (2, 5, 8, 9, 10, 11)
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3. A capacitance-accelerometer, comprising:
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a fixed electrode; and a movable electrode being supported by a cantilever at a portion adjacent to said fixed electrode having a gap thereinbetween; wherein grooves having openings which are disposed of at at least one side of said electrodes and are inter-connected with each other, are provided on a surface of said movable electrode, and said grooves are so arranged that electrode surface areas divided by said grooves are symmetrical with respect to a symmetrical axis parallel to said cantilever. - View Dependent Claims (4)
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6. A capacitance-accelerometer comprising:
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a fixed electrode; and a movable electrode being supported by an elastic body and facing said fixed electrode at a portion having a gap thereinbetween; wherein grooves are provided on a surface of said movable electrode to divide said surface into a plurality of electrode surface areas, said grooves are so arranged that said plurality of electrode surface areas divided by said grooves are uniformly balanced, and end portions of said grooves open to four sides of said movable electrode.
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7. A capacitance-accelerometer, comprising:
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a movable electrode being supported by an elastic body; and fixed electrodes, said movable electrode being disposed thereinbetween said fixed electrodes and said fixed electrodes facing respective surfaces of said movable electrode at a portion having a gap thereinbetween; wherein a plurality of grooves crossing each other on the surface of said movable electrode, end portions of said grooves open to an outside portion at the portion between said fixed electrodes and said movable electrode through openings, and through-holes leading to both surfaces of said movable electrode are formed at crossing points of said grooves.
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Specification