US1871478A - Color photography - Google Patents

Description

Aug.. 16, 1932. w. 1.-. TARBIN lcoLoR PHOTOGRAPHY Filed Jan. 2l, 1928 RED Fig. 2

K NA W described Patented Aug. 16, 1932 UNITED STATES WILLIAM THOMAS TARBIN, OF ECOLES,

.MESNE ASSIGNMENTS, TO AGFA YORK, A CORPORATION 0F N EW YORK MANCHESTER, ENGLAND, ASSIGNOR, '.BY

AN'SGO CORPORATION, OF BINGHAMTON, NEW

COLOR PHOTOGRAPHY Application filed January 21, 1928, Serial No. 248,391, and in Germany February 1, 1927.

This invention relates to the method of color photography, which expression as, used herein includes color cinematography, and photo-mechanical color printing processes, for example the half-tone, intaglio, collotype and like processes of pictorial reproduction in substantially natural color, by the exposure simultaneously of a plurality of superimposed layers of light-sensitive compositions differing one from the other in respect of their sensitivity to light rays forming particular bands of the spectrum in such manner as to enable a corresponding number of differently colored photographic images to be obtained by printing or projection, which when superimposed will form a composite representation of a subject in substantially its natural colors.

Usually the number of superimposed layers of light-sensitive composition employed and the number of differently colored photographic images which are arranged in superposition in processes of this kind are two or three, the process in the one case being as a two-color process and in the other case a three-color process.

Hitherto, processes of the kind in question, using a plurality of superimposed layers of light-sensitive composition, have not given wholly satisfactory results owing, lirstly, to the lack of definition or diiiusion of the image due to the scattering of light by the several layers and their supports and, secondly, to the length of the exposure needed in forming the negative.

The object of the invention is to provide an improved Film pack of the kind referred `to which shall not be open to the abovestated objections inherent in the prior proposals.

The invention is based upon the observation that the layer of light-sensitive composition which is selectively sensitive to the rays situated towards the blue end of the spectrum should be located in making the exposure to obtain the negative images farthest from the source of light.

A bromide emulsion of high sensitivity will normally be used as the layer of lightsensitive composition sensitive to blue in place of the chloro-bromide emulsions previously employed for forming the blue sensitive layer in the known processes.

Where `the invention is applied to the three-color process it would seem relatively immaterial whether the layer of composition sensitive to red or green is arranged immediately in front of the blue sensitive layer though in view of the fact that the so-called blue-printer is most importantin giving form and definition to the completed picture, it would be preferable for the red sensitive layer which gives the blue print) to be nearest to the light source, and in practice this will be the arrangement usually adopted.

The several layers of light-sensitive composition may be associated with a transparent suport or transparent supports in a variety ofmanners. In some cases it may be desirableor even necessary to employ layers of composition which may be stripped from the support; for example, in the three-color process the layer of composition sensitive to red may be in the form of a'stripping film attached to a transparent support such as glass or Celluloid while the layer of composition sensitive to green and the layer of composition sensitive to blue are non-stripping films on suitably transparent supports.

As will be understood, the support for the layer of composition which is located between the other two layers `of composition should be as thin as possible.

The invention will be described in detail and by way of example with reference to the accompanying drawing, in Which:-

Figure 1 is a section and F igurc 2 a front elevation plate.

of a composite .In the drawing, l is a sheet of glass coated with a layer of composition sensitive to red in the form of a stripping film 2, the layer of composition sensitive to green heilig in the form of a non-stripping film 3 on a thin celluloid support 4 with its coating in contact with vthe' layer of composition sensitive vto red while the layer'of composition sensitive to blue 5 is coated upon a sheet of glass 6, the layer being iarranged in contact withthe rear `face of the ypreviously-mentioned Celluloidl support.

Conveniently the supports for the several layers are secured together as shown in the drawing by clips 7 Which may be furnished with V-shaped notches 8 which during the I '6 .simultaneous exposure of the plurality of layers of light-sensitive composition will protect the compositions from the action of light and thereby leave impressions on the several images.

Certain of the layers of li ght-sensitive composition may be arranged to act as compensating filters, such films being dyed with nonsensitizing dyes While the opacity or translucency of the emulsions may be regulated to facilitate securing t-he desired degree of speed or sensitivity to light of the several lightsensitive layers.

By the arrangement of the several layers of li ght-sensitive Composition in the manner above defined and by the regulation of the sensitivity, opacity and translucency of the several layers, a means for producing negative images adapted for use in the production of composite representations in natural colors will be secured which Will be capable of Working at speeds comparable with the speeds of photographic plates and cut films.

The application of the invention to cinematography is described in the divisional application Serial No. 357,270, filed April 22, 1929.

Having now described my invention what I claim as new and desire to secure by Letters Patent is 1. A composite pack for color photography comprising a plurality of super-imposed layers of light-sensitive materials suitably arranged on transparent supports, said materials being selectively 4sensitive to light rays 40 forming particular bands of the spectrum,

which layers, after exposure and development, when super-imposed, Will form a complete, negative, composite representation of a subject in substantially its natural colors, and one of the layers of light-sensitive material being selectively sensitive to blue rays of light and being located farthest from the source of light, when the pack is exposed.

2. A tri-pack for color photography comprising three super-imposed layers of lightsensitive materials for simultaneous exposure, each layer being selectively sensitive to light rays of a primary color, the layer ofA the pack farthest from the light source during exposure being selectively sensitive to blue rays of light.

3. A tri-pack for color photography comprising three super-imposed layers of lightsensitive materials for simultaneous exposure, the layer of the pack nearest the light source during exposure being selectively sensitive to red rays of light, the layer farthest from the light source during exposure being selectively sensitive to blue rays of light, and

the layer intermediate thereof being selectively sensitive to green rays of light.

4. A composite pack for the three-color process of photography comprising a sheet of glass coated With a layer of composition selectively sensitive to red rays of light, in the form of a stripping film, a layer of composition selectively sensitive to green rays of light in the form of a non-stripping film of a thin Celluloid support with its coating in Contact with the layer of composition selectively sensitive to the red rays of light` and a layer of composition selectively sensitive to blue rays of light, coated on a sheet of glass, said layer being arranged in contact With the rear face of the sai d Celluloid support.

5. A composite pack for the three-color process of photography comprising a sheet of glass coated With a layer of composition selectively sensitive to red rays of light, in the form of a stripping film, a layer of composition selectively sensitive to green rays of light in the form of a non-stripping film of a thin celluloid support With its coating in contact With the layer of composition selectively sensitive to the red rays of light, a layer of composition selectively sensitive to blue rays of light, coated on a sheet of glass, said layer being arranged in contact with the rear face of the said celluloid support, and means for securing said layers together comprising clips having means for facilitating registration of the prints representative of the several colors of light rays for producing the composite image.

In testimony whereof' I have signed my name to this specification.

WILLIAM THOMAS TARBIN.

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