PROBLEM TO BE SOLVED: To provide an ultrasonic sensor which can sufficiently secure generation voltage at the reception in accordance with adjustment of the width of a lower electrode.SOLUTION: An ultrasonic sensor comprises: a diaphragm a lower electrode which is laminated on the diaphragm, has length L in a first direction along the surface of the diaphragm, and width Wbe equal to or less than the length L in a second direction orthogonal to the first direction along the surface of the diaphragm a piezoelectric substance which is laminated on the lower electrode, and has width Wpz in the second direction and an upper electrode which is laminated on the piezoelectric substance. The ratio Wbe/Wpz of the width Wbe of the lower electrode to the width Wpz of the piezoelectric substance is equal to or greater than 0.1 and equal to or less than 0.8.SELECTED DRAWING: Figure 12COPYRIGHT: (C)2016,JPO&INPIT【課題】下電極の幅の調整に応じて、受信時の生成電圧を十分に確保することができる超音波センサーを提供する。【解決手段】超音波センサーは、振動板と、振動板に積層されて、振動板の表面に沿って第1方向に長さLを有し、振動板の表面に沿って第1方向に直交する第2方向に長さL以下の幅Wbeを有する下電極と、下電極に積層されて、第2方向に幅Wpzを有する圧電体と、圧電体に積層される上電極とを備える。下電極の幅Wbeと圧電体の幅Wpzとの比Wbe/Wpzは0.1以上0.8以下である。【選択図】図12
