| 摘要 |
PURPOSE:To prevent forgery and alteration by providing a thermally recordable layer laid on a card base and a shielding layer which is laid partly on the thermally recordable layer and capable of infrared transmission and making the color developed part of the thermally recordable layer invisible. CONSTITUTION:A thermally recordable layer 2 is capable of thermally developing a pattern in color using a thermal head. The thermally colored patterned part is characteristic of absorbing infrared beam and the part where no color has developed is characteristic of reflecting infrared beam. On the other hand, a shielding layer 3 allows transmission of the infrared beam and does not allow transmission of a visible light. That is, the shielding layer 3 has properties which enable the infrared beam to be transmitted, and make the color developed part of the thermally recordable layer 2 invisible. Therefore, if a card is irradiated with an infrared beam, the patterned part 5 does not allow almost all of the infrared beam to be reflected in the infrared area, while the non-color developed area shows a high reflection factor. Subsequently, significant variations of the reflection factor permit the pattern to be read and thereby the authencity of the card can be identified and data such as value can be recognized. Thus it is possible to prevent forgery and alteration. |
