| 摘要 |
<p>PURPOSE:To obtain a plastic card that is remarkably difficult to forge or alter and easily discrimate a forged item in appearance by a method wherein one of first and second magnetic recording layers has a coercive force twice or more higher than the other and a Curie point lower than the other by a specific temperature or higher, and the saturation writing currents of the both are substantially made equal by heating the both in a temperature range from the lower Curie point down to a point a specific temperature lower than this point. CONSTITUTION:One of first and second magnetic recording layers 13, 14 has a coercive force twice or more higher than the other and a Curie point Tc lower than the other by 100 deg.C or higher, and the saturation writing currents of both the recording layers 13 and 14 are substantially made equal by heating the both in a temperature range from the Curie point Tc of the magnetic recording layer having the lower Curie point Tc down to a point 30 deg.C lower than the Tc. In this manner, the recording layer 13 serves as a magnetic layer having a high coercive force and a low Curie point, and the recording layer 14 serves as a magnetic layer having a low coercive force and a high Curie point, and vice versa. It is difficult that magnetic information simultaneously written at the same current value are simultaneously rewritten using a normal magnetic recorder.</p> |
