SEAM DETECTOR FOR SHEET INCLUDING METAL FOIL

摘要

PURPOSE:To make it possible for sure to detect a seam that has been electrically insulated and to obtain improved easiness of operation and simplification of electric circuit by arranging a pair of coils in opposed positions with a sheet in between them. CONSTITUTION:A seam 3' is detected 9a, 9b as a sheet 3 including a metal foil which has an electrically insulated seam 3' and the thickness of which is 20mu or less is made to travel. In this case a pair of coils 2a and 4a are juxtaposed in parallel to each other with their coil diameter being over 1.5 times the distance between a pair of coils 2b and 4b and their coil diameter. With this arrangement detection of the seam 3' is ensured.