Ultrasonic irradiation system.

摘要

An ultrasonic irradiation system has a transducer (1) which is composed of a plurality of elements divided at least in a circumferential direction of the face of the transducer (1) so that the phases of drive signals may be changed according to the respective circumferential positions of the oscillating elements. This permits the phases of the drive signals to be rotated by n rotations in the circumferential direction. As a result, an annular focal zone having a desired radius is formed, and the integrated values of sound waves in the circumferential direction may be substantially zero on the focal plane so that no unnecessary secondary focal zone is formed.