US2041317A - Photoengraving screen and process of producing same - Google Patents

Description

y 1936- c. E. BENSON 2,041,312

Pnowoxsmemwme SCREEN AND PROCESS OF PRODUCING SAME Filed May 22, 1935 =1 #3 EH" lt:

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CHARLES E. BENSON 51 A TTOENE Y5 Patented May 19, 1936- UNITED STATES PATENT OFFICE PHOTOENGRAVING SCREEN AND PROCESS OF PRODUCING SAME Application May 22, 1935, Serial No. 22,860

3 Claims.

This invention relates to screens for use in the art of photo-engraving and a new and novel process of producing same.

The invention is more particularly directed to half-tone and mezzograph screens, the former characterized by symmetrically placed, conventional, opaque and transparent square dots of uniform size as distinguished from a mezzograph screen which is made so as to produce grains of different degrees of fineness and not symmetrically placed. Such screens are employed for the purpose of obtaining fine tonal and artistic effects in half-tone prints produced therefrom. A halftone screen structurally embodies a grating or mesh consisting of clear finely polished glass panels, each ruled with parallel lines etched into the glass and filled in with an opaque substance, both pieces being connected together to dispose the rulings on one glass at exact right angles to the Q0 rulings on the other, leaving transparent square apertures between the rulings the size of which will be determined by the distance apart of the respective rulings. As distinguished from the features which characterize a halftone screen, a as conventional mezzograph screen is characterized by a grain structure in various degrees of grain fineness, the screen glass being coated with a resistant, which is treated so it will reticulate and produce a smooth, even, grained structure 80 with no opaque filling between the grains, as their form is such that light is refracted in passing through them to provide corresponding grain structures of. high lights and shadows on the negative.

It has been discovered'that any conventional screen of the kind above referred to can be employedwith whichto produce a new, novel and useful screen having the form of a photographic composite of such conventional dots or grains, 40 as the case may be, and a pattern of some suitable design, such as the weave of textile material, that is to say, canv'as, monks cloth or other pattern producing surface, whether of a textile nature or not, and that a halftone print of a copy 45 made through such-composite of these two structures will be enhanced to an appreciable degree,

the tonal effect and render to. the eye the impression that the reproduction is a print of a copy on canvas or other foundation or pattern 50 material;

' It is therefore an object of the invention to provide either a dot screen or a grain screen which has photographically superimposed thereon, so to speak, a photographic image of a particular distinctive pattern, upon which the photographed subject or copy will itself appear as having been directly painted thereon. in this manner, the copy or subject from which a halftone is tobe made can be placed in front of a copy board and photographed to provide a halftone negative 5 in the customary manner, except that instead of using a dot screen, use is made of a screen which is a composite of the pattern to be reproduced and a dot screen.

In the accompanying drawing, wherein has 10 been illustrated a preferred embodiment of the invention,

Figure 1 is a plan view of a conventional cross line screen ordinarily employed in the making of a halftone negative;

Figure 2 is a detail view of a section of pattern providing material;

Figure 3 is aschematic illustration wherein a. conventional halftone screen has been placed as usual in front of a sensitized plate in a process camera and the pattern material positioned on the copy board to be photographed onto the plate through said conventional cross line screen;

Figure 4 is a View of two half-tone pictures as produced by the photo-engraving screen and process embodying this invention.

Referring more particularly to the accompanying drawing, wherein like reference numerals indicate similar parts throughout the several views, {indicates a conventional process camera; 6 a sensitized plate in plate holder 1; and 8 a conventional halftone screen. A copy board 9 of usual construction is shown at l0 and mounted thereon is a pattern material H, such as canvas, monks cloth or any other well known pattern providing material upon which a light can be projected from a lamp I? as is the practice when photographing a copy.

Assuming that the screen 8 has been properly adjusted relative to the plate 6, and that the camera has been focussed for size and sharpness of the pattern material, exposure can now be made the same as'when making a halftone negative.

From a negative thus made, the same being a composite of a conventional dot screen and a pattern material such as described herein, a positive can now be made and subsequently employed in lieu of the customary dot or cross lined screen. A copy from which a halftone is to be made can nowbe photographed directly through this composite screen, and, as first above described, a print will appear to the eye as having been made from a copy on a particular pattern material. The degree of perceptibility of the pattern will be 55 1. The herein described method of making a photo-engraving screen which comprises exposing a sensitive photographic plate through a con" ventional photo-engraving screen and photographing upon the entire sensitized surface of the plate, the surface images of portions of a material of predetermined kind, whereby to provide a negative which is a composite of the images of the 'screen characterizing portions of the conventional screen and the images of the surface portions of the aforestated material, then making a positive from the negative adapted to he used in the making of prints in place of a conventional screen, so that the subject in the print when photographed upon a sensitized plate through said positive will appear as though mounted upon a backing having the surface characteristics of the atorestated material of predetermined kind.

2. The herein described method of making a photo-engraving screen which comprises exposing a sensitive photographic plate through a conventional photo-engraving screen and photographing upon the entire sensitized surface of the plate, the surface images oi. portions of a fabric material of predetermined kind, whereby to provide a negative which is a composite oi! the images of the screen characterizing portions of the conventional screen and the images of the surface portions of the aforestated material, then making a positive from the negative adapted to be used in the making of prints in place of a conventional screen, so that the subject in the print when photographed upon a sensitized plate through said positive will appear as though mounted upon a backing having the surface characteristics oi the aforestated material of predetermined kind. 3. The herein described method of making a photo-engraving screen which comprises exposing a sensitive photographic plate through a conventionnl photo-engraving screen and photographing upon the entire sensitized surface of the plate, the surface images of portions of a woven material of predetermined kind, whereby to provide a negative which is a composite oi the images of the screen characterizing portions of the conventional screen and the images of the surface portions of the aiorestated material, then making a positive from the negative adapted to he used in the making of prints in place of o. conventional screen, so that the subject in the prin when photograpl'lecl upon. a sensitised through said, positive will appear as though mounted upon a backing having the l acteristics oi the ai'orestatetl material oi? pro determined lzllid.

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