DE216610C - Process for the production of three-color screens for color photography - Google Patents

Description

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

CLASS 575th GROUP

FRITZ FAUPEL in BERLIN.

The present invention aims to produce three-color screens using use a method known per se, in which on a chromate gelatin layer under A system of lines is copied onto a cover grid, so that in the gelatin layer by exposure tanned lines lie next to unchanged lines that are opposite to dye solutions behave differently so that it is at

ίο single exposure succeeds in creating a two-tone Get grid.

For example, you can copy a black-and-white grid with about 20 lines per millimeter on a gelatinized and through potassium dichromate Light-sensitive celluloid or glass plates are created analogously to the grid a gelatin skin made of alternately tanned and untanned gelatin lines.

Since certain tar dyes have the property of coloring untanned gelatine, but not tanned while on the other hand other colors reverse tanned gelatin stain, on the other hand the untanned gelatin, so can be prepared as above Gelatin grid can be resolved in two basic colors by z. B. the untanned Lines with the solution of a blue dye, which is only absorbed by untanned gelatin is colored, the tanned lines on the other hand in a red dye solution, which only stains the tanned gelatin. You get in this way a colored system of lines that consists of 20 blue and 20 red per millimeter Lines.

Both dyes can be used in order to achieve the same and reliable coloration and intensity.

thus red and blue are mixed together in a certain proportion; it then occurs a coloring of the lines corresponding to the mixing ratio.

Azorubine, crystal ponceau 6 R, and the blue dyes methyl blue, brilliant wool blue G and brilliant aurine have proven to be suitable dyes for tanned gelatine.

If now the two-color lines thus obtained made raster sensitive to light again by bathing in potassium dichromate and the black and white raster copied at any angle to the first-prepared Liniatur, then the untanned the first ^process: and divided blue-stained line in tanned and untanned quadrangles. The excess potassium dichromate can be removed by brief rinsing without the color intensity of the colored gelatin being significantly impaired; for the dyes adhere very firmly to the gelatin and are only removed from the gelatine when it is soaked for a long time, while the potassium dichromate can be removed by a short, strong soak. Apart from this, however, depending on the nature of the dyes used, certain additives can be added to the wash-out bath, such as, for example, common salt or small amounts of acid, in order to exclude the possibility of even small parts of the dye being washed out as far as possible. If, after washing out the potassium dichromate, the plate is placed in a yellow dye solution that only stains the untanned gelatin, e.g. B. a solution of Chrome Fast Yellow G, the un-

tanned blue squares dyed green by over-dyeing with yellow.

The end result is now a color plate with red lines and intervening, evenly spaced blue and green squares. By any choice of line width of the black-and-white grid, the mixing ratios of red to blue and green be matched.

ίο You can see from this that with z. B. 20 lines per millimeter without difficulty 820 resolutions per square millimeter can be achieved thanks to their symmetrical Arrangement appear extremely calm and no longer noticeable to the unarmed eye are.

The color grid can of course also be produced in such a way that that the order in which the dyes are used is changes, so that you first create a red-yellow two-color raster and then after tanning the yellow lines the untanned parts of the latter with a blue one Dye treated to create a green color.

It is in the French patent 358250 the production of multicolor screens described, also dyes successively on tanned by exposure or untanned gelatine can be fixed. The present one differs from this method in the following points:

The new process is based on an uncolored chromate gelatin layer, on which then, after being broken down into tanned and untanned lines, a blue-red colored line system arises.

According to the procedure of French patent 358250 it is colored red Run out of chromate gelatin, and to get the blue lines it is necessary to First wash out the red from the unexposed lines in order to create these lines to color blue.

Just like the production of the two-colored ones initially formed in both processes Line systems is different, the other operations are also different from each other.

With the new process, the two-tone line system is directly used without one further overmolding, etc. used by placing the under the grid on the first exposure Untanned lines made photosensitive and then put through in any Angle to be copied black and white grid divided into tanned and untanned sections of which the unexposed when treated with a yellow dye solution and therefore the rectangles remained untanned in the blue lines and colored as a result go green.

In contrast, the method of French patent 358250 must have the first received blue-red colored line system initially a water-impermeable one Lacquer and then another colored chromate gelatin layer can be placed. On this The second layer repeats the same process that was used to dye the first Layer has served, only with the difference that this time the yellow washed out and is replaced by blue, while the lower gelatin layer is washed out and red was replaced by blue.

The operation described in French patent 358250 thus provides a four-color network, consisting of orange, purple, blue and green fields in two Layers that are separated by a waterproof layer. So there are two two-color grids placed one on top of the other, between which this one just mentioned waterproof layer is located. In contrast to this is the result of the new Procedure a three-color network consisting of red lines and blue and green square ones Fields that are all in a single layer.

Claims (1)

Patent claim: Process for the production of three-color grids by exposure of a chromate gelatin layer under a cover grid and coloring the exposed and unexposed areas in different colors, thereby characterized in that a gelatin layer dissolved by exposure into tanned and untanned parts of any shape first dyeing with two dyes, one of which dyes the tanned, the other the untanned gelatine, and that the untanned part can then be reused after treating the entire layer with bichromate decomposed into tanned and untanned elements by exposure and the latter with one on untanned Gelatin-absorbing third dye overstained.