| 摘要 |
<p>PURPOSE:To easily identify dropout or error in recording by a method wherein at least a part of the surface of a card in use is made of a frosted layer of a synthetic resin, an image is formed at a specific temperature and pressure at the time of recording, and the image is erased at a higher temperature. CONSTITUTION:A card C in use is provided with a frosted layer of a synthetic resin on at least a part of the surface thereof. In the case of entrance using this card, the frosted layer 1 is partially pressurized and smoothened by a thermal stamp method, whereby a flat image 2, such as predetermined characters and symbols, is formed thereon. Since the smooth image 2 is formed at a temperature higher than the glass transition temperature of the resin of the frosted layer 1 but lower than the melting point thereof, it has a strain inside and a tendency to return to the former frosted surface by reheating. In the case of exit, the card C is heated to above the temperature at the time of the pressurization, whereby the strain retained in the smooth image 2 is eliminated. Thus, the smooth image 2 is erased and returned to the former frosted surface.</p> |
