ELECTROMAGNETIC INDUCTION TYPE INSPECTION DEVICE AND METHOD
First Claim
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, anda 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, andwherein 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.
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Accused Products
Abstract
Any inspection object regardless of material can easily be inspected or discriminated with high accuracy and high sensitivity by being placed in a magnetic field generated by applying an alternating current to an exciting coil and detecting changes of voltage level and phase of electromotive force induced by a detection coil unit. The discrimination of the inspection object is performed on the basis of a DC voltage value with respect to a standard specimen and a phase differential voltage value with respect to a phase difference between the phase of a voltage signal from the induction coil and the phase of the exciting current to the exciting coil.
39 Citations
16 Claims
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1. An electromagnetic induction type inspection device comprising:
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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. - View Dependent Claims (2, 3, 4, 6, 7, 8)
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5. (canceled)
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9. An electromagnetic induction type inspection method comprising:
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generating a magnetic field by applying an alternating current having a phase to an exciting coil, detecting, by means of a detection coil unit, an electromotive force induced by the magnetic field generated by said exciting coil as a voltage value having amplitude and a phase, placing an inspection object in the magnetic field generated by said exciting coil, detecting a change in voltage value caused by placing said inspection object in the magnetic field, calculating, as a level-mode value, a first detection value relevant to said voltage value obtained from said detection coil unit, calculating, as a phase-mode value, a second detection value relevant to a phase difference between the phase of said voltage signal and the phase of the alternating current applied to said exciting coil, and subjecting said inspection object to one of inspection, identification and discrimination based on said first and second detection values, wherein said first detection value 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 said 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. - View Dependent Claims (11, 13, 15, 16)
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10. (canceled)
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12. (canceled)
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14. (canceled)
Specification