Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1998-02-18
1999-12-14
Hofsass, Jeffery A.
Communications: electrical
Condition responsive indicating system
Specific condition
3405723, 3405724, G08B 1314
Patent
active
06002335&
ABSTRACT:
A demagnetization apparatus for use with magnetically based electronic article surveillance systems having a dual status anti-theft marker containing at least one demagnetizable control element which when demagnetized allows the marker to be detected by the system when the marker is present in an interrogation zone. The apparatus includes an elongated magnetic section contained within a housing which exhibits a succession of fields of alternate polarity and at least a portion of which exhibits exponentially decreasing intensities at the working surface of the housing along that portion of the section. The section and a cover plate are orientated such that the external fields near the working surface are sufficient in intensities to demagnetize the demagnetizable element of the marker positioned proximate thereto while being rapidly attenuated a short distance from the section.
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Persson Erland K.
Zarembo Peter J.
3M Innovative Properties Company
Hofsass Jeffery A.
Olson Peter L.
Trieu Van T.
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