US498396A - William kurtz - Google Patents

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WITNESSE UNITED STATES PATENT GEFIcE.

WILLIAM KURTZ, OF NEV'YORK, N. Y.

PHOTOMECHANI'CAL PRINTING.

SPEGIFICATION forming part of Letters Patent No. 498,396, dated May 30, 1893.

Applioationiiled February 23,l 1893. Serial No. 463,328. (No model.) l

city, county, and State of'NeW York, have invented a new and useful Improvement in Photographic-Printng Methods, of which the following is a full, true, and exact specification,

reference being had to the accompanying drawings.

In printing chromos or colored prints on the lithographie, type, Lichtdruck, gelatine, photogravure, or any other press, either from halt-tone plates or from transfers on stone, which have been produced by the half-tone photoengraving process-or by similar methods, the prints show in spite of the most perfect register, a so-called moir-effect, a defect which may appear only in a few portions of the picture or recur regularly all over the picture in the form of a pattern'resemblingwatered silk, thus rendering it entirely Worthless. This moire-effect or confusion of lines is due to the fact that the colors are printed one over the other While they should really be arranged side-Wise of each other on the paper,

or cross each other in such a Way as to make confusion or moire impossible. To avoid this serions defect, instead of making a halftone negative of the yellow color, another of the red color and half-tone negatives for every other color that is to be used, all of which negatives would be produced by the screen or net in crossed lines, dots or stippled lines, my negatives are made in single lines by interposing in lieu of the screen or net, a glassplate ruled with parallel lines running in one direction only, so that the negatives show only one half of the picture or color to be reproduced, instead of the more fullyV modeled negatives in use heretofore.

My invention consists therefore in a process of photomechanical printing, in Which half-tone negatives are produced by exposing each plate with a screen With parallel lines running in one direction only, the lines of one negative running in a different direction from the lines of the other negatives, and then printing in colors from these half-tone negatives, so thatthe lines of the different plates will intersect each other in different directions.

In the accompanying drawings my improved plate is subjected to a single exposure through a screen, the parallel lines of which run in a different direction to the lines of the Iirst screen. rIhe remaining plates are likewise exposed in the same mannerthrough screens, the parallel lines Vof which run in directions differing from the first two screens. When a picture is to be printed, forinstance, in three colors, the color-plates are made from the halftone negatives which are obtained by single exposures by the interpositions of the screens,

shown in Figs. 1, 2 and 3, so that a picture representing one color is obtained in which the stripes run in one direction, say horizontally, as shown in Fig. 4, while the pictures obtained by the remaining color-plates are produced in stripes that run diagonally to the lines of the first plate and in opposite directions to each other, as shown in Figs.5 and 6.

The printing-plates are produced from the vhalf-tone negatives by the photo-etching process in the well-known manner, so that when the colors are printed onev over the other in colored printing inks,la picture is obtained, in which the light and shade ofthe original are fully shown, although each color has been photographed' for only one half of its area, the remaining half being taken up by the lines. The moire pattern or similar defects are thereby entirely obviated, as the color-stripes intersect each other and reproduce thereby theoriginal picture in a more complete and artistic manner. One of the colors may be printed from a grained plate and the picture then be completed by printing the other colors over the color produced by the grained plate from printing plates, the lines of which cross each other at right angles. When the picture is to be printed in four colors, a fourth printing-plate is used, the lines of which inlines run in diierent directions to each other, next producing printing plates from said halftone negatives and nally printing in different colors from these printing-plates, so that the lines of the different printing-plates will intersect each other in dierent directions, substantially as set forth.

In testimony whereof I have signed my n naine to this specification in the presence of two subscribing witnesses.

WILLIAM KURTZ. N Vtnesses;

OWEN WARD, CLARENCE R. COMES.

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