| 摘要 |
PROBLEM TO BE SOLVED: To form a satisfactory ultrasonic beam by detecting the center frequencies of received signals so as to take a deviation in time (corresponding to a depth) of center frequencies into consideration and control a delay or a phase process based upon the center frequency. SOLUTION: Arrayed ultrasonic vibrators 12 to a number of (n) receive signals with wave front arrival time difference from an objective focus point, and an amplifier 13 amplifies the received signals which are then digitized and are then delivered to a delaying part 10 where the wave fronts are aligned. Thereafter, they are added on an adder 11 so as to obtain an ultrasonic wave beam. Further, at this stage, in means 15 (15a to 15c) for obtaining a center frequency, center frequencies detected at respective received wave focusing stages, are delivered to a control part 16 which delivers focus date to a delaying part 10 or an A/D converter 1 so as to carry out delaying/phase-processing. With this arrangement, it is adjusted at the center frequency which varies with time in depending upon a depth, thereby affection upon the ultrasonic beam caused by a deviation of the ultrasonic waves is eliminated. |
