| 摘要 |
PROBLEM TO BE SOLVED: To provide a forgery prevention structure, which is hardly forged and has a concealed pattern that is hardly recognized with a usual visible light source and can be checked by an extremely simple verification method without using a specified polarization film or a specified verification device or the like, and to provide a forgery prevention sheet using the structure and a method for determining authenticity of the structure. SOLUTION: The forgery prevention structure 1, the forgery prevention sheet and the method for determining authenticity of the sheet are characterized in that: the forgery prevention structure 1 comprises a diffraction structure 2 having a concavo-convex pattern on one surface, a reflection layer 3 provided to cover the concavo-convex pattern, and a polarizer 4 provided on the whole surface in the side opposite to the reflection layer 3; and the diffraction structure 2 has a diffraction grating structure having a periodical cycle of≤400 nm and an aspect ratio of≥0.3 or a cross grating structure. COPYRIGHT: (C)2009,JPO&INPIT |
