| 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 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. Further, in the quartz plate 2, the thickness of a thin plate portion 22 is formed to be smaller than the thickness of a portion 21 formed with the electrode sandwiched by the excitation electrodes 31 and 41 to reduce the bent of the portion 21 formed with the electrode. With this, the change of the oscillation frequency due to the bent of the quartz plate 2 is reduced. <P>COPYRIGHT: (C)2013,JPO&INPIT |
