| 摘要 |
PURPOSE:To enable finding of flaw by means of ultrasonic beam which is high in focusing degree even in case a defect-finding distance is changed by changing a relative operation timing of an oscillator selected from a plurality of oscillators arranged in a row. CONSTITUTION:A unit selection signal S8 is added to a changing-over swich 3 in synchronism with an internal synchronizing signal of a control signal generation circuit 8, and a transmitting trigger signal S41, which is generated in a delay circuit 4 and is different in timing, is added to a selected transmitting and receiving device 2 and an oscillator 1. A reflection wave due to a flaw is fed to the delay circuit 4 through the oscillator 1 and the changing-over switch 3. An adder 5 adds a part, corresponding to a reflection wave produced in the proximity of a focus, to a receiving signal S42 which is phase-controlled, and a flaw detecting signal, selectively received, is indicated in a picture manner in an indicator 7. This causes changing of an opening corresponding to the flaw detecting distance and permits finding of a defect at an approximately similar precision irrespective of the flaw-detecting distance. |
