PROBLEM TO BE SOLVED: To provide a vibration waveform sensor using a piezoelectric device which can achieve both of high sensor sensitivity and noise resistance performance.SOLUTION: A pair of conductive pads 22, 23 and a piezoelectric element 30 are provided on a substrate 20, and a spacer 40 having conductivity surrounds the surrounding of them. The piezoelectric element 30 is configured so that, a polarization direction of a piezoelectric substance 32 is a vertical direction with respect to a direction where a pair of terminal electrodes 34, 36 face each other, the terminal electrodes 34, 36 are connected to the conductive pads 22, 23, so that the polarization direction becomes vertical to the substrate 20. On the piezoelectric body 32, polarization terminals 42, 44 are used for performing polarization to a d31 direction, for maintaining high sensitivity similar to that in a prior art. In addition, the polarization terminals 42, 44 are used only during polarization, and an inner conductor is not used for polarization, so that, a capacity of a vibration waveform sensor is a capacity of veneer, the capacity is about 1/10 of the capacity of a prior structure, and affection of noise can be avoided.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2018,JPO&INPIT【課題】高いセンサ感度と耐ノイズ性能の両立が可能な圧電素子を用いた振動波形センサを提供する。【解決手段】基板20上に一対の導電パッド22,23と圧電素子30が設けられ、これらの周囲が導電性を有するスペーサ40で囲まれる。前記圧電素子30は、圧電体32の分極方向が、一対の端子電極34,36の対向する方向に対して垂直方向であり、前記端子電極34,36を前記導電パッド22,23に接続して、前記分極方向が前記基板20に対して垂直になるように実装される。前記圧電体32には、分極端子42,44を用いてd31方向に分極を施すことで従来と同様の高い感度を維持する。また、分極時のみ分極端子42,44を用い、内部導体を分極に利用しない構造のため、容量的には単板となり、従来構造の1/10程度の容量となり、ノイズの影響を回避する。【選択図】図1
