PROBLEM TO BE SOLVED: To allow transmitting a bipolar waveform which has good positive/negative symmetric property.SOLUTION: An apparatus includes: a first transistor 72-1 which is inserted between a potential point P1 and a first electrode 71a of an ultrasonic oscillator 71 a forth transistor 72-4 which is inserted between a potential point P4 with a different potential from the potential point P1 and the first electrode 71a a third transistor 72-3 which is inserted between the potential point P1 and a second electrode 71b and an eighth transistor 72-8 which is inserted between a potential point P5 having the same potential as the potential point P4 and a second electrode 71b. The control circuits 74-1, 74-2 turn on the first and fourth transistors 72-1, 72-4 during a first transmitting period and turn on the second and third transistors 72-2 and 72-3 during the second trasmitting period different from the first transmitting period.COPYRIGHT: (C)2008,JPO&INPIT【課題】正負の対称性が良いバイポーラ波形を送信可能とする。【解決手段】電位点P1と超音波振動子71の第1の電極71aとの間に介挿される第1のトランジスタ72-1と、電位点P1とは異なる電位を持つ電位点P4と第1の電極71aとの間に介挿される第4のトランジスタ72-4と、電位点P1と第2の電極71bとの間に介挿される第3のトランジスタ72-3と、電位点P4と同じ電位を持つ電位点P5と第2の電極71bとの間に介挿される第8のトランジスタ72-8とを備える。制御回路74-1,74-2は、第1の送信期間に第1および第4のトランジスタ72-1,72-4をONし、第1の送信期間とは異なる第2の送信期間に第2および第3のトランジスタ72-2,72-3をONする。【選択図】図1
