Method for detecting metallic foreign matter and system for detecting metallic foreign matter

A metallic contaminant detecting apparatus comprising:

• conveying means having a conveyance path for conveying an inspection object contained in a package to detect a metallic contaminant accidentally mixed in said inspection object during a manufacturing process;
• metallic contaminant detecting means for detecting the metallic contaminant mixed in said inspection object by generating a magnetic field from a detecting element, provided in an intermediate portion of said conveyance path, said detecting element having a coil comprising a core and a conductor wound around said core;
• detection signal outputting means for generating a small magnetic field by applying a voltage to said coil or supplying an electric current to said coil, and for detecting a detection magnetic field generated from said metallic contaminant in response to said small magnetic field as a detection voltage or a detection current of said coil and outputting a detection signal;
• and
• a signal analyzing means for analyzing said detection signal to identify said metallic contaminant, wherein said small magnetic field is created by applying a small voltage to said coil or supplying a small electric current to said coil and using a non-linear portion of magnetic field characteristics of said core constituting said coil;
• a magnet booster disposed in said conveyance path upstream of said metallic contaminant detecting means, said magnet booster comprising magnet elements,
• wherein said magnet booster comprises at least two constituent parts disposed at respective positions facing each other across said conveyance path, and
• wherein said magnet elements forming said two constituent parts are disposed in such a manner that like magnetic poles thereof face toward said conveyance oath.