| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a magnetic card in which the balance amount of money, the remaining number of points and the like are hard to be altered, by forming a soft magnetic stripe which is irreversibly convertible when the stripe is irradiated with ultraviolet rays and which is composed mainly of manganese and bismuth. SOLUTION: In the magnetic card 1, a hard magnetic stripe 2 and a magnetic stripe 3 for collation, which is provided with a hard magnetic region 3-1 and a soft magnetic region 3-2, are formed on a synthetic resin support. In addition, a punched hole 4 is formed in the lower part. The magnetic stripe 3 for collation is formed in such a way that a manganese powder in a particle size of 10um and a bismuth powder in a particle size of 50μm are mixed in a ratio of 2 to 8 so as to be kneaded, that their mixture is put into a mold and that a pressure is applied so as to form a solid body. In addition, the magnetic stripe is formed in such a way that the solid body is baked at 250 deg.C and for eight hours in a nitrogen atmosphere by using an electric furnace. The magnetic stripe using these magnetic materials displays a soft magnetic property, the magnetic stripe does not generate residual magnetism even when it is magnetized by a magnetic head, and it cannot be written. However, the magnetic stripe is converted irreversibly when it is irradiated with ultraviolet rays, and it can be written and read out.</p> |
