US1288753A - Photographic-printing process. - Google Patents

Description

J. 'E. THORNTON.

PHO'TOGRAPHI C PRINTING PROCESS.

APPLICATION FILED JUNE 30.1915.

1,288',753. I Patented Dec. 24,1918.

2 SHEETS-SHEET 1 Fig.2.

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MW A 5 7 UNITED sTATEs PATENT onnron.

JOHN EDWARD THORNTON, or WEST HAMISTEAD, Lonnon, ENGLAND, nssrenon' To JOHN ownnn onnrnn, or MANCHESTER, ENQLAND.

PHOTOGRAPHIC-PRIHTING PROCESS.

To all wh m it may concern:

Be it known that I, JOHN Enwnnn THORN- TON, a British subject, residing, at West Hampstead, London, England, have invented certain new and useful Improvements in and Relating to Photographic-Printing Processes, of which the following is a specification.

- This invention relates to the manufacture or production ofcinematograph films upon a bichromated colloid or upon a similar slow printing surface, and is specially 1ntended for color printing where two or more colors are superimposed, though it can be used forsingle color work if desired. It forms an improvement upon the following applications recently filed by me in relation to this art; 733,633, filed November 26, 1912; 745,724, filed February 1,1913; 745,725, filed February 1, 1913;

772,440, filed June 7,1913; 38,016, filed July IIn some of those inventions, for example, United States applicationsSerial Nos. 760200 and 772440, superimposed prints in different colors are made from continuous duated negatives. upon material sen tone a sitizegf with bichromated colloids. Such prints may be developed from the front by stainmg with suitable dyes of the type that only stain soft gelatin and do not stain the The purpose of this in'vention'is to provide an improved process by which films-to' the colloid of which dye or pigment is added before rinting-are printed from the front, and eveloped from the front, without the necessity for any transfer or" after staining,

thereby securing greater simplicity and umformity than is possible when the coloring.

Specification of Letters Patent. Application filed June a. 1915. Serial m. 37,328.

760,200, filed April 10, 1913;

print; and

'bumen, gum,

Petented Dec. 24,1913.

matter or dye is added by means of developmentor staining after printing.

In the accompanying drawing Figure 1 is a perspective view of the film and sensitized layer; i

Fig. 2 is a face view or plan of the film with a sensitized layer on each side thereof;

.Fig. 3 represents a longitudinal section of the film and the sensitized layers on opposite sides thereof.

Fig. 4 is a diagrammatic view showing the method'of producing a positive print from a dot negative.

Fig. 5 represents a cross-section of the print obtained from the dot negative.

Fig. 6 is a diagrammatic view showing a method of obtaining a dot negative such as that shown in Fig. 4.

'- Fig. 57 is a diagrammatic view showing the method of arranging the dots indifferent positio'n's" inthe successive pictures of the final Fig. .8 is a diagrammatic yiew showing the relative positions of the dots of the pictures when projected in succession upon a screen. I

In carrying out the invention the film or othersupport 1 is first coated with a sensitized colloid 2such as gelatin, fish glue, al-

or mixtures thereof, -'in which igment or elsedg e of the desired color has con incorporate The sensitized film is exposed from the front for the requisite period of time to print under a screen printing through to the base, negative 6 of the special type hereinafter described, then developed, washed, and dried.

If the colloid be gelatin, hot water is used for development; and if it be fish glue, albumen or gum, cold water is used for development.

The development. is rendered capable of accomplishment from the front of the sensitized colloid. 2 (Fig. 4) and a sharp carbon print thus obtained because of'the breaking up of the image into a large number of very fine dots (say) about forty thousand to the s'quare'inch) y the use of a screen printing negative6 known-as a' process negative in which the-image is composed of a similar number of fine dots or lines, such negatives being used for halftone block making and other .well knownv photo-mechanical processes. Fig. 4 shows diagrammatically the I ness in inverse ratio to that of the negative,

and the whole of the dots composing the image are insoluble from back to front, the

soluble portions having been dissolved and washed away during development.

By using such a negative the light is obstructed by the lines or dots and the image is broken up into non-continuous blacks and half-tones, the tones being of uniform density and varying in area, instead of the regular graduated tones of varying density that would be obtained by using a graduated continuous tone negative.

The efiect of this is to leave the bichromated colloid in the form of having unprinted spaces that dissolve completely away during development, leaving intervening parts composed of insoluble colloid (containing pigment or dye) extending right through from the front to the base which stand up as lines or dots owing to the light which passes through the transparent spaces between the dots of the negative, penetrating through to the base supporting the colloid film, and thereby rendering it insoluble so that the pigment or dye is locked up in the insoluble portions of colloid.

The resultant image is one having a somewhat grainy appearance, but is more transparent than one in continuous graduated tones.

The screen printing negative 6 which is used in accordance with the present invention is made, as shown diagrammatically in Fig. 6, by placing acontinuous tone positive cinematograph film 8, which latter is made by contact from the original continuous tone negative, in front of a powerful light 9 and placing behind such film a sensitive silver bromid film 10, a dot screen 11 being interposed between the two films.

Upon developing the sensitive film so exposed the screen negative 6 will result bearing a series of images that are counterparts of the original except that they consist of dots or grain varying in .size and closeness, thus producing a picture in broken tones instead ofcontinuous tones.

This film is used as a negative for producing the required cinematograph films.

By suitable modifications of screen, diaphragm, light distances, and exposure, a variety of efi'ects are obtainable according to character of subject and other governing factors.

For cinematograph films in two or more colors, (multi-colors after the style of the Lumiere autochrome. screen plates or the Sanger-Shepherd superimposed prints), the positive film is sensitized, printed and developed, two, three or four times, each time from one of these special screen negatives according to number of colors required, each sensitizing and printing being superimposed upon the preceding one as set forth in my pending applications Serial Nos. 760200 and The special broken tone or screen printing negatives for such color Work may be made in the manner already described, either from continuous tone negatives, each of which represents one color only, out of the two, three or four colors; or they may be made from a multi-color negative of the Lumiere film; but where two prints are made on opposite sides of the same piece of film they ma be sensitized together and printed simultaneously.

By coating two layers of sensitized emulsion in two colors on one side of thefilm such as red and green, one on top of the other, and then exposing through a red filter, and then giving a second exposure through a green filter, two colors may be printed immediately one after the other, and developmentof the two proceed simultaneously. In this case a two-colorfinished pic-' ture is obtained at one complete operation.

The same efi'ect may be got if the two layers of colored sensitized emulsion 3 and 4 are coated upon opposite sides of the film 5, as shown in Figs. '2 and 3.

By coating the other side of the film with a third layer of colored sensitized emulsion a three color picture is obtained.

And b coating the second side of the filmthe reproduced grainy or screen printing negative, as shown diagrammatically in Fig. 7 so that the lines or dots of each picture i come in a different place on the projection the relative ppsitions of the dots of the successive pictures as projected onto the screen being shown diagrammatically in Fig. 8.

It will be understood that the term negative applies to the transparent cliche used in printing the final print, but it may be either a negative or a positive according to the'character of print desired.

The image may be converted into and printed in the form of fine lines instead of fine dots if preferred.

mm I claim as my inventionand desire to protect by Letters Patent is c 1. In the production of a cinematograph films by the carbonprocess upon a colored sensitized colloid, the improved process which comprises preparing from an ordinary cinematograph full tone negative a reproduced negative of broken tones or dots and printing through such reproduced nega'-' tive and through'said colored sensitized colloid from front to back to produce a final .print composed of dotsof colo'red colloid all of the same height or thickness but varying in theirarea or distance of separation which dots have been rendered insoluble.

2. The process of producing cinematograph films from a negative taken by a camera which consists in printing from the negative on to a sensitized film to produce a positive, photographing such posltive through a screen onto another film to pro\ duce a screen printing negative and finally printing therefrpm, on to the front and through to the back of a colored sensitized film and developing same from the front.

3. In the process of roducing multi-color cinematograph films by superimposing a plurality of printings of section color pic tures on the same film, preparing each color which the film is composed, said dots being\ of uniform depth or height, the area of or distance between the dots varying to give varying gradation oflight and shade to different parts of the picture and which dots are obtained through the intervention of a screen. 4

5. A cinematograph film having a series of. pictures superimposed thereon, each picture being represented in dots of gelatin of which the film is composed, the dots being of uniform depth or height and the area of or distance between the dots varying to give varying gradation of lightand shade toeach picture. 7 p

In testimony whereof I have hereunto set my hand in presence of a subscribing Witness.

- JOHN Witness:

I. OWDEN OBRIEN.

EDWARD THORNTON.

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