| 摘要 |
PURPOSE:To enable a very precise detection of flows with an inexpensive circuitry, by relatively moving a probe with respect to material to be inspected to input a signal into a flaw signal extraction circuit from the probe corresponding to the condition of the surface of the material being inspected. CONSTITUTION:A flaw detector 2 having a probe 6 is turned about material 1 to be inspected with a rotation device 3. Detection coils 9 and 10 wound on magnetic poles 7 and 8 are differentially connected to the probe 6 and one and the other end of the coils serve as output point 11 for a flaw signal. Then, when detecting flaws of the material 1 being inspected, the probe 6 outputs the flaw signal of the waveform sequentially varying - rising, falling and rising again sequentially - from the output point 11. On the other hand, this probe 6 is connected to a flaw signal extraction circuit 16 via an eddy current detec tion circuit 15. Then, the circuit 16 outputs a signal to a marker driving circuit 18 from the output point 11 only when the signal varies - rising, falling and rising again sequentially - and matches at least the predetermined time for the falling section thereof. |
