Detection apparatus for security systems
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United States of America Patent
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-
Sep 6, 1994
Grant Date -
N/A
app pub date -
Dec 26, 1991
filing date -
Feb 28, 1990
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
An electronic article surveillance system is provided that comprises a core-wound drive coil which produces an AC magnetic interrogation field, and a detection coil provided on one side with at least one element of a screening material, which detection coil detects an AC magnetic response field generated by a magnetically active tag or marker which is subjected to the interrogation field when the tag or marker comes in proximity with the detection coil. The screening material may take the form of an open-ended electrically conductive box having an insulating gap along its length, or a laminate consisting of a plurality of metal foils interleaved with an electrically insulating material. The invention provides well-defined flux control for the detection coil which preventsinterference from unwanted external magnetic fields.
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