Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – For magnetizing or demagnetizing
Patent
1987-06-24
1988-06-21
Harris, George
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
For magnetizing or demagnetizing
324260, 361151, 340572, H01F 1300
Patent
active
047527587
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 a portion of which exhibits generally decreasing intensities at the working surface of the housing along that portion of the section. The peak intensity of the outermost field is controlled to have a peak intensity less than that of adjacent regions. The section and a cover plate are oriented 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. Accordingly, magnetically sensitive articles, such as for example, prerecorded magnetic cassettes, to which the markers are affixed, are not adversely affected.
REFERENCES:
patent: 3665449 (1972-05-01), Elder et al.
patent: 3747086 (1973-07-01), Peterson
patent: 3790945 (1974-02-01), Fearon
patent: 4003336 (1977-01-01), Koester et al.
patent: 4271782 (1981-06-01), Bate et al.
patent: 4499444 (1985-02-01), Heltemes et al.
Prodt. Info. Brochure from 3M entitled "Plastiform"-Permanent Magnet Mat. Prod. No. B-1060, (Pl-1.6H).
Prodt. Info. Brochure from 3M entitled "Plastiform"-Permanent Magnet Material Product Nos. B-1030, (PL-1.4H), B-1013, (PL-1.4H).
Barte William B.
Harris George
Minnesota Mining and Manufacturing Company
Sell Donald M.
Smith James A.
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