公开(公告)号：DE2950174A1

公开(公告)日：1981-06-19

申请号：DE2950174

申请日：1979-12-13

Applicant: BASF AG

Inventor： KOESTER EBERHARD DIPL PHYS DR ,  HACK JOACHIM DIPL ING ,  STEUERWALD MANFRED

IPC: G06K19/10 ,  G06K7/08 ,  G06K19/12 ,  G07D7/04 ,  G11B5/00 ,  G11B23/30 ,  G07D7/00 ,  G06K19/08 ,  B44F1/12

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.

公开(公告)号：DE2162440A1

公开(公告)日：1973-07-05

申请号：DE2162440

申请日：1971-12-16

Applicant: BASF AG

Inventor： HARTMANN JOB WERNER DR ,  ROLLER HERMANN ,  HARTMANN HANS JOERG DR ,  HARTMANN HEINRICH DR ,  HACK JOACHIM DIPL ING

IPC: G11B5/70 ,  C09D5/23 ,  G11B5/702 ,  G11B5/842 ,  G11B5/68