| 摘要 |
A technique capable of accurately and easily detecting external force applied to a piezoelectric plate is provided. A crystal plate 2 is cantilever-supported in a container 1. Excitation electrodes 31, 41 are formed on an upper face and lower face, respectively, for example in a center portion of the crystal plate 2. On a front end portion of a lower face side of the crystal plate 2, a movable electrode 5 connected via a lead-out electrode 42 to the excitation electrode 41 is formed on the lower face side, and a fixed electrode 6 is provided on a bottom portion of the container 1 to face this 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 crystal plate 2 bends by external force applied, capacitance between the movable electrode 5 and fixed electrode 6 changes, and this capacitance change and a deformation of the crystal plate 2 are regarded as a change in oscillation frequency of the oscillation circuit 14. Further, an angle ¸ formed between a direction in which external force is applied and a direction of the movable electrode 5 along a length direction of the crystal plate 2 before the external force is applied is set to 30° to 60°, preferably 40° to 50°, to perform measurement. |
