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Information recording medium and method for recording and reproducing information to a medium to prevent unauthorized copying

  • US 5,886,979 A
  • Filed: 03/14/1997
  • Issued: 03/23/1999
  • Est. Priority Date: 10/21/1996
  • Status: Expired due to Term
First Claim
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1. An information recording medium capable of rewriting information by a recording operation and an erasing operation, comprising:

  • plural unit areas composed of a plurality of bits on an information recording area, the unit areas having an irreversible unit area(s) recorded irreversibly and a non-irreversible unit area(s) not recorded irreversibly, wherein a predetermined key information is recorded by the arrangement of the irreversible unit area(s) and the non-irreversible unit area(s).

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