| 摘要 |
<p>PURPOSE:To enable a specific sheet to be determined, by a method wherein, a plate having a repeated pattern is provided on the plate surface of an endless plate body, and a plate having either a pattern which has been made by slightly reducing the pattern on the plate of the aforesaid plate body or a different pattern is formed on the plate surface of the other endless plate body. CONSTITUTION:A pattern P1 is formed on a plate 81 of an endless plate body 61, and a pattern P2 is formed on a plate 82 of an endless plate body 62. The pattern P2 is of the same form as the pattern P1, but is formed by being multiplied by a very low ratio of reduction in the plate-making. For example, if the length of the plate body 62 is made slightly smaller than that of the plate body 61 and an endless printing is made on a sheet 3 with the plates 81, 82 of the plate bodies 61, 62, the discrepancy in the patterns occurs in a small amount with every rotation of the plate bodies 61, 62. As a result, the patterns return to an original pattern when a printing corresponding to a least common multiple of the lengths of the plate bodies 61 and 62 is accomplished. Therefore, by reading these patterns by, for example, an optical reader, the difference between the patterns can be identified. Thus, the time of printing, date of issuance, and others of the printed matter are known by reading the patterns.</p> |
