Patent ID: 7696747
Filing Date: 2010-04-13
Classification: G01N

Abstract:
1. An electromagnetic induction type inspection device comprising: a sensor having an exciting coil generating a magnetic field with application of an alternating current having an exciting phase and a detection coil unit for detecting a change of the magnetic field of said exciting coil, and a signal processor for calculating, as a level-mode value, a first detection value relevant to a voltage value of a voltage signal outputted from said detection coil unit and, as a phase-mode value, a second detection value relevant to a phase difference between the phase of the voltage signal and the exciting phase of the alternating current applied to said exciting coil, to inspect, identify or discriminate an inspection object based on the first and second detection values, wherein said first detection value in said signal processor is obtained by subtracting a DC voltage value obtained by amplifying and rectifying a standard voltage signal outputted from said detection coil unit when placing a standard specimen in the magnetic field generated by said exciting coil from a DC voltage value obtained by amplifying and rectifying the voltage signal outputted from said detection coil unit, and wherein said second detection value in said signal processor is obtained by subtracting the phase differential voltage value relevant to the phase difference between the phase of the standard voltage signal outputted from said detection coil unit for the standard specimen and the phase of the exciting voltage of said exciting coil from the voltage value relevant to the phase difference between the phase of the voltage signal outputted from said detection coil unit for the inspection object and the phase of the exciting voltage of said exciting coil.