PROBLEM TO BE SOLVED: To simultaneously increase harmonic components and attenuate fundamental 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 a three-layer piezoelectric body, three layers are laminated in a manner that directions of polarization are partially reversed without laminating three layers with aligned directions of polarization, and the electrode layering is devised. Specifically, electrodes on surfaces on the separating sides of the mutually adjacent piezoelectric bodies are connected each other and are respectively connected to two terminals in parallel. Then, when the direction of the residual polarization of a piezoelectric body 2 is the same direction (+P), and the direction of the residual polarization of a piezoelectric body 3 is the opposite direction (-P), using the direction (+P) of the residual polarization of a piezoelectric body 1 as a reference, the sensitivity of the electric displacement between the terminals is canceled at &lambda/4 resonance, and is emphasized at 3&lambda/4 resonance. Consequently, the fundamental wave is suppressed, and the tertiary harmonics 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とともに、電極引回しを工夫する。具体的には、互いに隣り合う圧電体の離反側の面の電極同士を連絡して2つの端子にそれぞれ並列接続する。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を同方向(+P)、圧電体3を逆方向(-P)とすると、端子間の電気変位は、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次調波を抽出することができる。【選択図】図16
