METHOD FOR DETECTING METALLIC FOREIGN MATTER AND SYSTEM FOR DETECTING METALLIC FOREIGN MATTER

摘要

A method and a system for detecting a metallic foreign matter mixed into an article to be inspected, e.g. a food, a medical product, an industrial material, and the like, wrapped by a conductive packaging material of aluminum, or the like. A faint magnetic field is generated by applying a voltage or supplying a current to coils (10, 11) and the magnetic field from a metallic foreign matter is detected, in the form of a detection voltage or a detection current of the coils (10, 11), in response to the faint magnetic field and a detection signal is outputted. The metallic foreign matter is detected by analyzing the detection signal. The faint magnetic field utilizes the nonlinear part in the magnetic field characteristics of a core constituting the coils (10, 11) where the voltage being applied to the coils (10, 11) or the current being supplied thereto is very small.