| 摘要 |
PURPOSE:To detect short-axis defects and long-axis defects with high accuracy by operating a differential methof flaw detecting circuit and an absolute method flaw detecting circuit alternately, and parallel-recording the outputs thereof on the same recording paper. CONSTITUTION:A bridge circuit is constituted of a pair of coils 2, 3 of the same characteristics wound coaxially on a probe and disposed in proximity to each other and variable impedances 31, 32, and is operated as a detecting part for a differential method flaw detecting circuit. A dummy coil 4 which is so selected as to make the impedances 31, 32 negligible is connected in parallel with the coil 3, and constitutes a bridge circuit together with variable impedances 39, 40. It is operated as a detecting part for an absolute method flaw detecting circuit. One group of switches 43, 45, 57, and one group of 44, 46, 48 turn on and off periodically and synchronously, respectively. The outputs from the respective detection parts are fed to a phase detector 36, the outputs whereof are parallel-recorded discretely on the same recording paper. |
