| 摘要 |
The invention concerns a printed security document which comprises, for example, a background pattern formed from points or lines. In order to protect the document against copying, an object, for example the text "BEWARE OF FORGERY", is incorporated into this uniform background pattern. The text is incorporated such that, at the points where the text is located, the individual lines of the background pattern are split into two partial lines which are each only approximately half as wide as the original line. This division of the components of the background pattern is invisible or only visible with difficulty to the naked eye. If an original printed security document of this type is copied on a conventional photocopier, although the copy shows the original, relatively wide lines of the background pattern, the partial lines formed by their division will not be copied at all, or only very badly, such that the text "BEWARE OF FORGERY" appears clearly on the copy. |
