| 摘要 |
<p>656,235. Photo-mechanical printing plates. INTERCHEMICAL CORPORATION. July 17, 1947, No. 19108. Convention date, July 5, 1940. [Class 98 (ii)] [Also in Group XL (b)] The continuous variation of tone of an original representation is reproduced by photoelectric scanning and reproducing apparatus (see Group XL (b)) in the form of a recorded photographic image, or a printing plate made therefrom, by means of spaced rectangular dots of black and white on light and dark backgrounds respectively, in which both dimensions of the dots and the spacing between the centres of the dots are varied with the tone of the original. The image plates may be used in typographical or lithographical processes, Figs. 1, 2, 3 (not shown), and in the case of an intaglio process, Figs. 4, 5, white dividing lines 5a of small width are formed in the dark areas to produce narrow ridges 5 in the intaglio plate.</p> |
