Acceleration sensor
First Claim
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1. An acceleration sensor comprising:
- a weight;
a vibrator for supporting the weight at the center of gravity thereof, wherein the vibrator has such a cut angle that the piezoelectric constant in the longitudinal direction of the weight is zero and the piezoelectric constant in the thickness direction of the weight is also zero and for detecting an in-plane acceleration, the vibrator being positioned in a center of the weight in a longitudinal direction of the weight such that a center of rotation being located at a position further out than the vibrator in the longitudinal direction;
a first circuit that adds up outputs generated from two regions formed by dividing a surface of the vibrator into two in the longitudinal direction of the weight and provides output detection signals corresponding to translational acceleration; and
a second circuit that outputs the difference between the outputs and provides output detection signals correspond to angular acceleration, andwherein the weight having a size greater than that of the vibrator in the longitudinal direction, andwherein a sense signal based on the in-plane angular acceleration being output across detection electrodes provided on the vibrator.
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Abstract
An acceleration sensor includes a weight and a vibrator that supports the weight at its center of gravity. When acceleration is applied to the weight, stress equivalent to the applied acceleration is generated in the vibrator. As the vibrator is arranged to support the weight at its center of gravity, a characteristic relationship is observed between the acceleration, such as angular acceleration or translational acceleration, and the size of electric charges and the polarity. By taking advantage of this relationship, different types of acceleration can be easily detected.
46 Citations
12 Claims
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1. An acceleration sensor comprising:
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a weight; a vibrator for supporting the weight at the center of gravity thereof, wherein the vibrator has such a cut angle that the piezoelectric constant in the longitudinal direction of the weight is zero and the piezoelectric constant in the thickness direction of the weight is also zero and for detecting an in-plane acceleration, the vibrator being positioned in a center of the weight in a longitudinal direction of the weight such that a center of rotation being located at a position further out than the vibrator in the longitudinal direction; a first circuit that adds up outputs generated from two regions formed by dividing a surface of the vibrator into two in the longitudinal direction of the weight and provides output detection signals corresponding to translational acceleration; and a second circuit that outputs the difference between the outputs and provides output detection signals correspond to angular acceleration, and wherein the weight having a size greater than that of the vibrator in the longitudinal direction, and wherein a sense signal based on the in-plane angular acceleration being output across detection electrodes provided on the vibrator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An acceleration sensor comprising:
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a weight; a vibrator for supporting the weight at a center of gravity thereof, wherein the vibrator has such a cut angle that a piezoelectric constant in the longitudinal direction of the weight is zero and a piezoelectric constant in the thickness direction of the weight is also zero, and for detecting an in-plane acceleration, the vibrator being positioned in a center of the weight in a longitudinal direction of the weight such that a center of rotation being located at a position further out than the vibrator in the longitudinal direction, and a circuit that outputs detection signals corresponding to angular acceleration and translational acceleration, the detection signals being obtained by processing outputs generated from two regions formed by dividing a surface of the vibrator into two in the longitudinal direction of the weight, and wherein the weight has a size greater than that of the vibrator in the longitudinal direction, wherein a sense signal based on the in-plane angular acceleration is output across detection electrodes provided on the vibrator.
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Specification