| 摘要 |
PURPOSE:To enable detection of a defect at a fixed accuracy without use of any amplifier, by varying a defect detecting voltage according to an attenuation curve of an ultrasonic wave. CONSTITUTION:A defect detecting circuit with a distance corrector comprises an attenuation curve memory mode in which an attenuation curve of an ultrasonic wave is memorized and a defect detection voltage output mode with a distance correction in which a defect detection voltage is generated from the attenuation curve. In the attenuation curve memory mode, several identical artificial defects are provided on a test piece and a probe is moved to memorize an attenuation curve obtained from an echo height measuring circuit 1 and a path measuring circuit 2 into a digital memory 4. In the defect detection mode, a path counter started up by a repetition timing signal from a synchronization circuit 3 is connected to obtain an output thereof as reading address for the digital memory 4 and an echo height data read is inputted via a D/A converter 5 into an attenuator 6 for setting a defect detecting voltage. A comparator 7 compares an input from an ultrasonic signal input terminal 8 with the defect detecting voltage.
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