PROBLEM TO BE SOLVED: To provide an array type ultrasonic transmitter for high intensity convergence ultrasonic treatment, in which ultrasonic output per drive voltage is high, the transmitter being formed from a piezoelectric element that is able to apply a high electric field to a piezoelectric body at a relatively low drive voltage and is less in heat generated even in highly ultrasonic output.SOLUTION: A resonance characteristic is not obtained by thickness resonance but is obtained by mechanical resonance in the width direction. Thus, a spherical curvature can be imparted to a piezoelectric element structure in the direction of ultrasonic radiation surface and/or back thereof, the piezoelectric element structure being able to decrease the distance between electrodes in a thickness direction.COPYRIGHT: (C)2012,JPO&INPIT【課題】比較的低い駆動電圧により高電界を圧電体に印加でき、かつ、高超音波出力時にも発熱が少ない圧電素子よりなる、駆動電圧あたりの超音波出力が高い高強度集束超音波治療用のアレイ型超音波送波器を提供する。【解決手段】共振特性を厚み共振でなく幅方向の機械的共振により得ることにより、厚み方向の電極間距離を縮めることを可能とする圧電素子構造を、その超音波放射面および背面の両方またはどちらか一方に、球面状の曲率を与えることにより実現する。【選択図】図4
