| 摘要 |
PROBLEM TO BE SOLVED: To detect a flaw on the surface of a container accurately by irradiating an object with a continuous ultrasonic wave, detecting an abnormality in the shape of reflected wave caused by a flaw, converting the abnormality into an electric signal and comparing with a normal electric signal. SOLUTION: An object 1 is irradiated with a continuous ultrasonic wave transmitted from a transducer 4 (transmitter) and an abnormality in the shape of reflected wave caused by a flaw in the object 1 is detected by a transducer 4 (receiver). It is then converted into an electric signal and comparing with a normal electric signal. More specifically, when an acoustic wave impinges on a flat surface having a flaw, scattering wave and interference wave due to the irregularity of flaw are superposed on the reflected wave thereof and apparent absorption attenuation takes place in the sound pressure of reflected wave. The flaw is detected based on the drop in the sound pressure level. Ultrasonic wave of 80-1000kHz is preferably employed. The object 1 includes the body part, neck part, etc., of a glass bottle. |
