Dynamic sensor having capacitance varying according to dynamic force applied thereto
First Claim
1. A dynamic sensor comprising:
- a semiconductor substrate;
a stationary member formed on the semiconductor substrate, the stationary member having elongate stationary electrodes;
a movable member anchored on the semiconductor substrate, the movable member having elongate movable electrodes facing the stationary electrodes and forming a capacitance therebetween which varies according to a dynamic force applied to the movable electrodes, wherein;
a plurality of projections are formed on either the stationary electrodes or the movable electrodes or on both electrodes, the projections having various heights so that the highest projections first hit the electrodes facing the projections when an excessive dynamic force is applied to the dynamic sensor.
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Accused Products
Abstract
A dynamic sensor includes stationary electrodes and movable electrodes facing each other and forming a capacitance therebetween. The capacitance changes in accordance with a dynamic force such as acceleration imposed on the sensor. Plural projections are formed on the stationary electrodes to avoid or suppress electrode sticking between the movable electrodes and the stationary electrodes due to an excessive impact imposed on the sensor. The projections are formed to have various heights so that higher projections first hit the movable electrodes and thereby protect lower projections. Even after the higher projections are destroyed by the excessive impact, the lower projections remain intact and serve to prevent the electrode sticking by the excessive impact which may occur later.
13 Citations
11 Claims
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1. A dynamic sensor comprising:
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a semiconductor substrate;
a stationary member formed on the semiconductor substrate, the stationary member having elongate stationary electrodes;
a movable member anchored on the semiconductor substrate, the movable member having elongate movable electrodes facing the stationary electrodes and forming a capacitance therebetween which varies according to a dynamic force applied to the movable electrodes, wherein;
a plurality of projections are formed on either the stationary electrodes or the movable electrodes or on both electrodes, the projections having various heights so that the highest projections first hit the electrodes facing the projections when an excessive dynamic force is applied to the dynamic sensor. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A dynamic sensor comprising:
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a semiconductor substrate;
a stationary member formed on the semiconductor substrate, the stationary member having elongate stationary electrodes;
a movable member anchored on the semiconductor substrate, the movable member having elongate movable electrodes facing the stationary electrodes and forming a capacitance therebetween which varies according to a dynamic force applied to the movable electrodes, wherein;
the elongate stationary electrodes are supported on the semiconductor substrate at one end thereof, forming cantilevers;
the movable member includes an elongate center rib and a flexible beam resiliently swinging according to a dynamic force applied to the dynamic sensor, the elongate center rib being anchored on the semiconductor substrate at both ends thereof, the elongate movable electrodes being connected to the center rib, forming cantilevers; and
a plurality of projections for restricting an excessive swinging motion of the flexible beam are formed on the flexible beam. - View Dependent Claims (8, 9, 10, 11)
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Specification