| 摘要 |
PROBLEM TO BE SOLVED: To obtian a method to perform a self-diagnostic operation without making the shape of an electrode complicated, and to obtain a three-axis acceleration sensor with a self-diagnostic function. SOLUTION: A sensor part 20 is constituted of a flexible member 21, a piezoelectric element 23, and a weight body 24. Four fan-shaped detecting electrodes 26 are formed on the surface of the piezoelectric element 23 on the X-axis and the Y-axis so as to be axis-symmetric with respect to the X-axis and the Y-axis. The circumferential; part of every detecting electrode 26 is formed inside a line, in which a stress becomes zero when a force is applied to the direction of the Z-axis. In addition, a circle-shaped detecting electrode 28 is formed on the surface of the piezoelectric element 23 at the outer side from the line. By this constitution, the detecting sensitivity in the direction of the three axes can be made nearly equal. An electrode 29 is formed nearly on the whole rear surface of the piezoelectric element 23. Four derivative electrodes are derived from the electrode 29 to the surface of the piezoelectric element 23. |
