| 摘要 |
PURPOSE:To perform directivity control on a time delay basis through a simple circuit constitution, by controlling directivity by time delay. CONSTITUTION:A pulse train 22 from a pulse train generator 3 has a period T and is lsintheta/c when a composite beam faces in a direction theta, and the period is controlled by previously given theta (where l is intervals of vibrator and C is the velocity of an acoustic wave). Transmitted pulses 23 from a transmitted pulse generator 7 are inputted to a shift register 4 and shifted by the pulse train 22, thereby generating delay transmitted pulses 24-1-24-m at respective stages. Those pulses 24-1-24-m are inputted to one-side terminals of gates 5-1-5-m and higher harmonic pulses 21 are supplied to the other-side terminals; and the gates 5-1-5-m outputs higher harmonic pulses 25-1-25-m having higher harmonic pulses only in sections of the pulses 24-1-24-m. The pulses 25-1-25-m are frequency-divided by (n) through frequency dividers 6 to generate a basic wave 26 containing pulses of frequency (f) only in the sections of the pulses 24-1-24-m. This basic wave 26 has the frequency (f) of the ultrasonic wave radiated from each stage of an ultrasonic wave vibrator 1 in the sections of the pulses 24-1- 24-m and its starting time of the frequency (f) is delayed each by lsintheta/c. Thus, the composite beam of ultrasonic waves is generated in the direction theta. |
