| 摘要 |
PROBLEM TO BE SOLVED: To prevent forgery and alteration even when magnetic information is duplicated, by a method wherein a means for holding thermally-changeable storage information and a protective layer are provided and the means for holding the thermally-changeable storage information is made to have a structure not allowing to see the information. SOLUTION: In a forgery preventing card 1 such as a prepaid card, necessary information is recorded as bar-code-shaped information in a thermal recording part 3. A protective layer 5 is a layer of a thin film of opaque plastic and, therefore, the recorded information can not be seen from outside. On the occasion when the card 1 thus prepared is used, an infrared light is cast on the card 1 from an infrared light casting element when the card is inserted into a card reader, the light reflected from the thermal recording part 3 through the protective layer 5 is detected by a sensor and the information of the recording part 3 detected thereby is sent to a processing device. After completion of the use, the processing device calculates the amount of the use, subtracts it from a residual amount of the card 1 and makes a heating head change physical properties of a prescribed position of the recording part 3 according to the information on the residual amount. |
