Improvement in the printing of articles suitable for use as documents, improvement in printing plate to work slot.The process of preoduzir a transitional image for printing slot and the article printed

摘要

1390302 Fraud preventing; intaglio printing AMERICAN BANK NOTE CO 6 July 1973 [6 July 1972] 32383/73 Heading B6A nad B6C A printed article produced by an intaglio printing process has a record medium 11 on which are printed ink pattern elements 14, 14(a) which have an appreciable depth forming an image and a background such that at one angle of view the image is undetectable and at another it appears in clear contrast. As shown in Fig. 1 an image of the letters A B C D denoted by dashed line is produced by portions 14a of parallel lines 14 being deeper than the rest of the line and is undetectable when viewed normal to the paper but appears in clear contrast when viewed from an angle L as shown in Fig. 3. The image may be formed from lines at an angle to the background, Fig. 5, which may also have an overall pattern formed from local differences in line spacing superimposed to obscure the image when viewed from above. Alternatively the image may be formed of lines lower than and between the background lines so that the image disappears at low angles of view as shown in Fig. 15. Instead of lines dots may be used. In an alternative embodiment the surface of the medium may be printed with a multi-colour image in discrete colours and the intaglio image printed thereon so that one of the colours is obscured at acute angles of view giving an apparent colour change. An intaglio plate is also described and claimed.