| 摘要 |
PROBLEM TO BE SOLVED: To effectively prevent an illegal copy by displaying predetermined information by using ink reversibly discolored by at least one of heat received by an object read by an emitting light and heat received by a human body at the time of contact with the body. SOLUTION: A railway ticket 10 has a base material 11, a ground ting 12 printed on the material 11, and a mark 13. Ink of the mark 13 contains, for example, electron donative coloring organic compound, electron acceptive compound, discoloring temperature regulator and solvent. When an image of the ticket 10 is read by an image information reader, a surface of the ticket 10 receives heat from the reader, and the mark 13 is discolored. Accordingly, the image of the mark 13 cannot be read, and a copy of the ticket 10 is not copied with the image of the mark 10. Thus, the image of the ticket cannot be copied as it is to prevent its illegal copy. |
