| 摘要 |
<p>PROBLEM TO BE SOLVED: To detect a minute metal piece included in a body to be inspected. SOLUTION: In the metal detector a transmitting coil 6 to which an AC excitation signal is applied and a receiving coil 15 are arranged along the conveyance path of the body 1 to be inspected and the coils are connected in series to each other and further there are provided coils 15a and 15b which have different winding directions and are arrayed along the conveyance path so that the wiring directions have specific patterns, reference signal memories 19a and 19b which store reference signals outputted from synchronous detectors 9a and 9b when a reference metal piece is conveyed to the conveyance path, correlation calculation parts 18a and 18b which find and output correlation signals between the output signals of the synchronous detectors and the reference signals stored in the reference signal memories, and a decision part 26 which judges that the object body includes a metal piece when the values of the correlation signals outputted by the correlation calculation parts exceed a specific threshold.</p> |
