PROBLEM TO BE SOLVED: To equalize frequency response to low frequencies in the shorter axis direction of an ultrasonic probe.SOLUTION: In the ultrasonic diagnostic system, a piezoelectric layer 2 includes: a piezoelectric layer 2-3 (first piezoelectric layer) of which one surface is an ultrasonic wave-outputting surface a piezoelectric layer 2-4 (second piezoelectric layer) laminated on the other surface of the ultrasonic wave-outputting surface of the first piezoelectric layer a common electrode 8 provided on a lamination boundary surface between the first piezoelectric layer and the second piezoelectric layer to which ultrasonic signals are supplied a first ground electrode 7-1 provided on the ultrasonic wave-outputting surface of the first piezoelectric layer and a second ground electrode 7-2 provided on a backside on the other side of the lamination boundary surface of the second piezoelectric layer. The first piezoelectric layer and the second piezoelectric layer are respectively formed in specified thickness. On the backside of the electrode in contact with the second piezoelectric layer, a regulation layer 9 is provided which comprises material having sound impedance similar to that of piezoelectric material composing the piezoelectric layer. The regulation layer is formed in such a way that its thickness in the shorter axis direction perpendicular to the arrangement direction of an ultrasonic vibrator gets gradually thicker from a center toward the end.COPYRIGHT: (C)2009,JPO&INPIT【課題】超音波探触子の短軸方向の低周波に対する周波数応答を均等化する。【解決手段】圧電層2が、一方の面が超音波射出面となる圧電層2-3(第1圧電層)と、第1圧電層の超音波射出面の反対面に積層された圧電層2-4(第2圧電層)と、第1圧電層と第2圧電層の積層境界面に設けられ、超音波信号が供給される共通電極8と、第1圧電層の超音波射出面に設けられた第1の接地電極7-1と、第2圧電層の積層境界面の反対側の背面に設けられた第2の接地電極7-2を備えた超音波診断装置において、第1圧電層と第2圧電層がそれぞれ一定の厚みに形成され、第2圧電層に接する電極の背面に、圧電層を構成する圧電材に近い音響インピーダンスを有する材料からなる調整層9を設け、調整層は超音波振動子の配列方向に直交する短軸方向の厚みが中心部から端部に向かうにつれて徐々に厚く形成されてなる。【選択図】図7
