Transverse magnetic field annealed amorphous magneto-mechanical elements for use in electronic article surveillance system and method of making same

摘要

A marker for use in a magneto-mechanical electronic article surveillance (EAS) system comprises an amorphous magneto-restrictive strip (12) formed of a Fe-Co alloy contg. at least 30 at. % Co. Also claimed are: (i) a method of making this marker comprising mounting the strip near a biasing element (16) providing a dc magnetic biasing field so that the element has a resonant frequency; (ii) an EAS system using the above comprising a means of generating an alternating e.m. field including an interrogation coil in an interrogation zone and the marker above secured to an article for passage through the zone, along with biasing element. A detector detects the resonance of the element in the alternating field.