| 摘要 |
PURPOSE:To improve a detecting accuracy and a reliability by providing an inspecting coil of a small diameter placed concentrically with an exciting coil of a large diameter for generating a high frequency alternating field, and processing a detecting signal by using a phase shifter and a synchronous detector. CONSTITUTION:As for an eddy current flaw detecting probe, an exciting coil 2 of a large diameter and an inspecting coil 3 of a small diameter are arranged concentrically. A high frequency current is supplied to the coil 2 from an oscillator 31, and an eddy current is generated on an inspecting surface 7. A mutual induced volage by the eddy current is generated in the coil 3, and a variation of the induced voltage is inputted to synchronous detectors 5, 6 through a differential amplifier 32. A high frequency signal from the oscillator 31 is led to a 360 deg. phase shifter 60 deg. and a 90 deg. phase shifter 50. The detector 5 outputs a component (flaw signal) whose phase is shifted by 90 deg. with respect to a standard phase in an output signal from the coil 3, and the detector 6 outputs a component (lift-off signal) of a standard phase direction. In this way, the detecting accuracy of a flow and the reliability can be improved. |
