Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – For magnetizing or demagnetizing
Patent
1983-05-20
1985-02-12
Harris, George
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
For magnetizing or demagnetizing
340572, H01F 1300
Patent
active
044994443
ABSTRACT:
A desensitizer apparatus for use with magnetically based electronic article surveillance systems having a marker containing at least one magnetizable section which when magnetized, alters the response of the marker produced by an alternating magnetic field provided in an interrogation zone. The apparatus includes a magnet assembly having an elongated permanent magnet section and a pair of elongated pole pieces which concentrate external fields produced by the magnet sections near a gap extending the length of the magnet section, the external field near the gap being sufficient in intensity to magnetize the magnetizable section of a marker positioned proximate thereto, and being rapidly attenuated a short distance from the gap. Accordingly, magnetically sensitive articles such as prerecorded magnetic recording cassettes to which the markers are affixed are not affected.
REFERENCES:
patent: 3665449 (1972-05-01), Elder et al.
patent: 3781661 (1973-12-01), Trikilis
patent: 4378582 (1983-03-01), Maier et al.
Heltemes Eugene C.
Montean Samuel
Barte William B.
Harris George
Minnesota Mining and Manufacturing Company
Sell Donald M.
Smith James A.
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