| 摘要 |
Upper electrodes (A1 to A5) are disposed on an upper surface of a disk-shaped piezoelectric element (10). On a lower surface of the piezoelectric element (10), an annular groove to surround origin O is formed at position corresponding to the upper electrodes (A1 to A5). At the portion where the annular groove is formed, the piezoelectric element (10) includes a flexible portion formed so as to have thin thickness. When the peripheral portion of the piezoelectric element (10) is fixed to the casing, the central portion positioned within the annular groove functions as a weight caused to hang down from the flexible portion. On the lower surface of the piezoelectric element (10), a lower electrode (B) is formed. When force is applied to the weight by acceleration, the flexible portion is bent. As a result, predetermined charges are produced in the upper electrodes (A1 to A5) with the lower electrode (B) being as a reference potential. Accordingly, applied acceleration can be detected. When a predetermined a.c. signal is delivered between the lower electrode (B) and the upper electrodes (A1 to A5), the weight is oscillated in a predetermined direction. Accordingly, angular velocity can be detected on the basis of Coriolis force applied to the weight. Thus, simple sensor capable of detecting both acceleration and angular velocity in three. dimensional directions can be realized.
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