| 摘要 |
PROBLEM TO BE SOLVED: To accurately identify the internal defect of a sample without being affected by the characteristics of a transducer by detecting the presence/absence of the internal defect by comparing the positive and negative values of reflected wave signals with each other. SOLUTION: An ultrasonic transducer 12 converts the impulse signal of a transmitting section 11 into an ultrasonic wave and radiates the wave upon a sample 1. The transducer 12 converts reflected waves from the front and rear surfaces and inside of the sample 16 into reflected wave signals and a gate section 18 only extracts the internally reflected wave signal for identifying defect. When the sample 16 has no internal defect, the peak value of the reflected wave signals becomes negative > positive and the signals do not pass through an HPF 20 and are halved by means of a switch 21. One half of the signals is detected 22, sent to a comparing section 25, and stored in a memory 28 as picture data. The other half is detected 24 after polarity inversion 23 and sent to the comparing section 25. The signal of the compared result becomes off. When the sample 16 has an internal defect, the peak value becomes positive > negative and the signals pass through the HPF 20. The compared result of the signal becomes on. The on/off of the signals are displayed 30 as defect identifying data together with the picture data. |
