| 摘要 |
<p>A magnetic recording medium having an irreversible recording layer whose saturation magnetization changes irreversibly by heating in order to prevent alteration of data. The magnetic recording medium has, at least in part of its substrate, an irreversible recording layer containing an irreversible recording material whose saturation magnetization changes irreversibly by heating. A fixed information recording region for recording fixed information on the medium is formed at least in part of the irreversible recording layer. In the fixed information recording region, a plurality of heated bars whose saturation magnetization has changed irreversibly are arranged substantially in parallel with one another. The arrangement pattern of the heated bars or the arrangement pattern of unheated bars provided between adjacent heated bars is formed by coding the fixed information by frequency modulation or phase modulation.</p> |
