Method and apparatus for monitoring a series of products

摘要

PCT No. PCT/GB90/00469 Sec. 371 Date Feb. 4, 1991 Sec. 102(e) Date Feb. 4, 1991 PCT Filed Mar. 29, 1990 PCT Pub. No. WO90/12316 PCT Pub. Date Oct. 18, 1990.Monitoring a series of products of the kind in which the presence of foreign bodies in the product being monitored is detected by the characteristic magnetic field phase difference each material exhibits. The signal generated by a satisfactory product having no foreign body in it is used as the datum for judging whether the next subsequent product is free from a foreign body or not.