Acceleration sensor with oppositely-polarized piezoelectric plates
First Claim
1. A testable acceleration sensor comprisinga base (3);
- at least one piezoelectric element (1), mounted on said base (3), and formed as a sandwich structure of at least two piezoelectric plates (2) superposed on each other and having respective opposite polarizations, and an intermediate solid layer (10) mechanically interconnecting said plates; and
at least two electrodes (9) applied to each of first and second lateral portions (11a, 11b) of said piezoelectric element;
wherein,said lateral portions (11a, 11b) are electrically isolated from each other by an air gap (13) but are mechanically coupled to each other by a mechanical bridging means (12); and
the sensor is testable by applying an electrical voltage to electrodes on said second lateral portion (11b), thereby causing a bending deformation of said element (1), said bending deformation giving rise to a test signal which is detectable at electrodes (9) on said first lateral portion (11a).
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Abstract
An acceleration sensor, which is particularly adapted for use in motor vehicles, is improved by structuring it to be readily testable, to assure reliability before installation. The acceleration sensor has a piezo element (1), which consists of at least two piezo-electric plates (2) placed on top of each other, the piezo-electrical polarization of which is oriented in opposite directions. At least two electrodes (9) are placed on each of the topside (7) and the underside (8) of the piezo element (1). For testing the sensor, the piezo element is deformed by the application of an electrical voltage to electrodes (9) of a first lateral portion (11a) of the piezo element. This deformation is detected by means of a deformation-generated voltage at the electrodes (9) of a second lateral portion (11b) of the piezo element.
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Citations
12 Claims
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1. A testable acceleration sensor comprising
a base (3); -
at least one piezoelectric element (1), mounted on said base (3), and formed as a sandwich structure of at least two piezoelectric plates (2) superposed on each other and having respective opposite polarizations, and an intermediate solid layer (10) mechanically interconnecting said plates; and at least two electrodes (9) applied to each of first and second lateral portions (11a, 11b) of said piezoelectric element; wherein, said lateral portions (11a, 11b) are electrically isolated from each other by an air gap (13) but are mechanically coupled to each other by a mechanical bridging means (12); and the sensor is testable by applying an electrical voltage to electrodes on said second lateral portion (11b), thereby causing a bending deformation of said element (1), said bending deformation giving rise to a test signal which is detectable at electrodes (9) on said first lateral portion (11a). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification