| 摘要 |
PURPOSE:To remarkably raise detection accuracy of a flaw, by converting a time series signal detected by a flaw detecting circuit to a signal distribution of the surface of a body to be inspected, and extracting a feature of the flaw from this signal distribution. CONSTITUTION:Signal detecting circuits 200, 300 fetch an impedance variation of a pair of detecting coils 109, 110 in a rotary probe 100 by each bridging circuit, and output it as detecting signals na, nb. The signal na has positive and negative values by making a flaw F as a boundary, and its extreme value is elongated like a ridge in parallel with the flaw F on both sides of the flaw F. Accordingly, it is known that the flaw F is in the middle of this extreme values, but it is difficult to decide the end part of the flaw. On the other hand, the signal nb comes to have an extreme value in the vicinity of the end part of the flaw F. Accordingly, the end part of the flaw F is decided easily, but whether 2 extreme values are related to each other or not cannot be decided. Therefore, from both signals of the signal na and nb, the end part of the flaw, namely, its length can be decided. |
