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CODED MAGNETIC CARD AND SYSTEM FOR ENCODING AND SENSING THE SAME

  • US 3,788,617 A
  • Filed: 06/12/1972
  • Issued: 01/29/1974
  • Est. Priority Date: 10/18/1967
  • Status: Expired due to Term
First Claim
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1. A magnetically coded card including a sheet of magnetic material characterized as a homogeneous sheet in which magnetic material is diStributed throughout a plastic-like base, a. said sheet being permanently magnetized at a plurality of first portions having randomly shaped first areas over the face of the sheet, the first portions being magnetically poled along lines perpendicular to the opposite faces of the sheet, some of the first portions exhibiting north poles on one face and south poles on the opposite face and others of the first portions exhibiting south poles on one face and north poles on the opposite face, b. said sheet further including magnetized code bearing second portions having second areas smaller than said first areas and distributed over the face such that some of the second areas lie wholly within some of the first areas and others of the second areas intersect common boundaries of the first areas to lie partially in adjacent first areas, said second portions being magnetically poled along lines perpendicular to the opposite faces of the sheet, some of the second portions exhibiting north poles on said one face of the sheet and south poles on the opposite face and others of the second portions exhibiting south poles on the one face and north poles on the opposite face, such that any second area which lies wholly within a first area wherein the corresponding second portion exhibits the same pole as the first portion defining the first area, is undetectable whereby the particular arrangement and location of the magnetized code bearing second portions are undetectable in the absence of a previous knowledge of said particular arrangement and location as a consequence of the presence of said first portion.

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