| 摘要 |
PROBLEM TO BE SOLVED: To obtain the superior method in which authenticity of magnetic cards can be discriminated. SOLUTION: A magnetic card 10 has a magnetic layer A2 which is formed on a base body 1. A magnetic head is set close to the layer A2 and prescribed information is recorded. Then, one directional magnetic field is applied to conduct a first order erasing process. Then, another one directional magnetic field is applied in the opposite direction to conduct a second order erasing process. Then, pulse shaped reproduced output waveforms are reversed before and after the erasing processes to detect the differences in the polarities. |
