| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an external force detection device capable of precisely detecting an external force applied to a piezoelectric plate with a simple structure. <P>SOLUTION: A quartz plate 2 is cantilever-supported in a container 1. The quartz plate 2 has excitation electrodes 31 and 41 formed on the upper face and the lower face in, for example, a central area thereof. The quartz plate 2 has a movable electrode 5 formed on the lower face side in a front end area thereof so as to be connected to the excitation electrode 41 on the lower face side via an extension electrode 42, and a fixed electrode 6 is formed on the bottom of the container 1 opposing to the movable electrode 5. The excitation electrode 31 on the upper face side and the fixed electrode 6 are connected to an oscillation circuit 14. When the quartz plate 2 is bent by an external force applied thereto, the capacitance between the movable electrode 5 and the fixed electrode 6 changes. The capacitance change is obtained as a change of the oscillation frequency of the quartz plate 2. In order to prevent the damage of the front end of the quartz plate 2, a projection 7 is formed so that, when the quartz plate 2 is excessively bent, the projection 7 comes into contact with a stem portion of the quartz plate 2 before the front end of the quartz plate 2 collides with an inner wall of the container 1. <P>COPYRIGHT: (C)2013,JPO&INPIT |
