| 摘要 |
<p>PURPOSE:To effectively prevent illegal usage of a copying machine by providing a 1st section composed of 1st-pattern-like dots where the possibility that fine elements comprising a dot are adjacent to each other is high and a 2nd section composed of 2nd-pattern-like dots where the possibility that fine elements comprising a dot are adjacent to each other is low. CONSTITUTION:The sheet is formed of the 1st section 2 composed of the 1st- pattern-like dots so that the possibility that the fine elements for comprising the dot is high and the 2nd section 3 composed of the 2nd-pattern-like dots so that the possibility that the fine elements for comprising the dot is low. A hidden image which cannot be discriminated by the naked eye is formed by printing on the surface of the sheet A, and information 1 is recorded thereon. Consequently, when the density of a copying machine is adjusted to take a copy at a low density so that the hidden image cannot appear, the information is difficult to see, whereas if a copy is taken at a high density so that the information is visible, the hidden image looks sharp.</p> |
