PROBLEM TO BE SOLVED: To simultaneously increase harmonic components and attenuate basic wave components in transmitting and receiving harmonics by using a laminated piezoelectric body for an ultrasonic transducer in a medical ultrasonic diagnostic apparatus.SOLUTION: In transmitting and receiving third harmonic waves by using the three-layer piezoelectric body, the directions of polarization of three layers is partially arranged in a reverse opposite direction without laminating three layers with the aligned directions of polarization. Specifically, electrodes at both ends are connected to terminals to connect the respective piezoelectric bodies in parallel. Then, when the directions of the residual polarization of the piezoelectric body 2 and the piezoelectric body 3 are arranged to be the opposite direction (-P) by using the direction (+P) of the residual polarization of the piezoelectric body 1 as a reference, the sensitivity of an electric field between terminals is canceled at &lambda/4 resonance, and is emphasized at 3&lambda/4 resonance. Consequently, the basic wave is suppressed, and the third harmonic waves are extracted without using a filter or an amplifier.COPYRIGHT: (C)2012,JPO&INPIT【課題】医療用超音波診断装置において、超音波トランスデューサに多層圧電体を用いて高調波を送受波するにあたって、高調波成分を増加させると同時に基本波成分を減衰させる。【解決手段】3層圧電体を用いて3次高調波を送受波するにあたって、その3層を分極方向を揃えて積層するのではなく、一部の向きを逆方向にする。具体的には、両端の電極を端子に接続して各圧電体を直列接続する。そして、圧電体1の残留分極の向き(+P)を基準として、圧電体2および圧電体3を逆方向(-P)とすると、端子間の電場は、λ/4共振ではその感度が打ち消され、3λ/4共振においては強調される。こうして、フィルタやアンプを用いることなく、基本波を抑え、3次高調波を抽出することができる。【選択図】図15
