| 摘要 |
PURPOSE:To obtain a small-sized vibration detector detecting vibration applied to the case sufficiently and to improve the sensitivity by opposing a fixed electrode to a movable electrode, and by forming a metallic layer with the thickness thicker than that required for electric function of an electrode on the movable electrode to increase the mass. CONSTITUTION:In the movable electrode 6 obtained by treating a metallic foil or a polyester film by metal evaporation or the like, the metallic foil or the metal-evaporated layer is increased in thickness to increase the mass of the electrode 6 by using the weight. If vibration is applied to the case 4, the movable electrode 6 is oscillated, the change of capacity is generated between the movable electrode 6 and the fixed electrode 9 and the change is applied to an FET11 as an electric signal. If it is defined that the charge of an electrolet 10 is Q and the capacity between the movable electrode 6 and the fixed electrode 9 is C, the voltage V applied to the FET11 is expressed by V=Q/C. The source 11c of the FET11 is connected to the case 4 through an earth pattern 12a of a printed circuit board 12 and earthed. The electrode 6 is sharply oscillated by the weight of the evaporated layer in accordance with the externally accelerated vibration and outputs high output voltage. |
