| 摘要 |
<p>PROBLEM TO BE SOLVED: To record pieces of inherent fixed information which are different at every recording medium, when pieces of the information are issued and to make their alteration difficult by forming a magnetic thin film composed of a specific material which can be recorded only in a demagnetized state on a base material, together with a rewritable information recording layer. SOLUTION: In the magnetic recording medium 1, a magnetic pattern 4 in which a plurality of magnetic codes 3 are arranged on a base material 2 at equal intervals, by which a unidirectional recording operation can be performed and by which inherent fixed information can be recorded at the time when it is issued, is formed. At the same time, a rewritable information recording layer 5 is formed at the front of the base material 2, and a concealment layer 6 by which the magnetic pattern 4 and the magnetic recording layer 5 are concealed and a surface protective layer 7 are formed. At this time, a magnetic thin film at the magnetic pattern 4 is composed of an Mn-Bi cyclic crystal. When it is magnetized at room temperature from a demagnetized state at a coercive force of 600 to 1000Oe, an initial magnetization characteristic is saturated at 1/2 or lower the coercive force, and the coercive force is 10kOe or higher at this time, and the magnetic thin film can be recorded only in a demagnetized state. Thereby, pieces of fixed information which are different at every recording medium can be set and recorded, and their alteration becomes difficult.</p> |
