| 摘要 |
<p>PURPOSE:To enable the recording of fixed information simultaneously with subtraction information and to improve a security property by forming magnetic patterns of combinations of magnetic materials having specific coercive forces on a track indicating the subtraction information. CONSTITUTION:The magnetic patterns consisting of the combinations of magnetic bars A13 which are the magnetic material having the coercive force lower than the coercive force of external magnetic fields at the time of information reading and are saturated by the external magnetic fields of a prescribed value or below and the magnetic bars B14 which are the magnetic materials having the coercive force lower than the coercive forces of the external magnetic fields and are satd. by the external magnetic fields of a prescribed value or above are formed in the punched track indicating the subtraction information. The adequate reading is, therefore, not possible unless both values of bias voltage values and slice levels are adjusted. Then, it is difficult for a forger to find out a plurality of the combinations of the bias voltage values and bias levels effective for reading and there are no chances for the forger to know the presence of the fixed information. Since the subtraction information and the fixed information coexist in proximity, the security property is improved.</p> |
