Electricity: measuring and testing – Magnetic – Magnetic information storage element testing
Patent
1980-12-03
1983-08-02
Strecker, Gerard R.
Electricity: measuring and testing
Magnetic
Magnetic information storage element testing
148129, 235449, 324224, 34082534, 360 53, G01R 3312, G06K 900
Patent
active
043968864
ABSTRACT:
A process for authenticating recording media which are to be safeguarded against falsification and which possess discrete regions of an exchange-anisotropic magnetic material, by comparison of the polarity of a residual magnetization which is left over, because of the exchange anisotropy of the magnetic material, from a predetermined initial magnetization after exposure of the material to a specific temperature cycle and, subsequently, to a magnetic AC field which decreases to zero, with the polarity of a residual magnetization formed in the same way from an opposite initial magnetization, and an apparatus for carrying out the said process.
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Hack Joachim
Koester Eberhard
Steuerwald Manfred
BASF - Aktiengesellschaft
Strecker Gerard R.
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