| 摘要 |
PURPOSE:To so record information as to be impossible or difficult to be visually recognized by providing one specific wavelength range having 30% or more of difference of spectral reflectivity in a near infrared ray range, and providing two layers which are impossible or difficult to visually recognize it. CONSTITUTION:The first and second reflecting layers 1 and 2 of an information recording sheet both have one specific wavelength range having 30% or more of difference of spectral reflectivity in a near infrared ray range of 700-2,500nm in such a manner that the reflectivity of the first layer 1 is larger than that of the second layer 2. The first and second layers 1 and 2 are both impossible or difficult to be visually recognized, and can be identified only by utilizing a near infrared ray detecting system. In order to be difficult to visually recognize the first layer 1 from the second layer 2, they are formed to be achromatically, and an arbitrary pattern shape such as a character, a graphic, a bar code, etc., is, for example, formed on the layer 2. |
