Patent ID: 7626502
Filing Date: 2009-12-01
Classification: G08B

Abstract:
1. An acoustic-magneto security label with resonating frequency centered at 56-60 kHz comprising: a housing defining a resonating cavity; a resonator piece positioned within said resonating cavity; a soft magnetic bias piece supported on said housing proximate to said resonator piece, said soft magnetic bias piece having direct current coercivity measured in the range of 6.0-10.0 Oe and alternating current coercivity measured at 60 kHz being greater than 12 Oe, said soft magnetic bias piece being constructed from a Fe-Ni (45-55 wt %) soft magnetic alloy being cold rolled with greater than 80% reduction to a thickness in the range of 0.03 to 0.08 mm without application of any heat treatments after cold rolling; and a top cover affixed to said housing to seal said soft magnetic bias piece and said resonator piece within said housing.