US1930291A - Production of cinematograph film - Google Patents

Description

Oct. 10, 1933. '0. E. THORNTON PRODUCTION OF CII'EMATOGRAPH FILM Tig.

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lOOOOOOUODOUODO/ Oct. 10, 1933. J. E. THORNTON 1,930,291.

PRODUCTION OF CINEMATOGRAPH FILM Filed DeC. 31, 1931 2 Sheets-Sheet 2 mwn///l//a/d IIIIllllllllllllllllllllllllllllll n /raas @ver Figli.

Patented ocr. 1o, 1933 y UNITEDl STATE-s PMIrNT` OFFICE Application December 31, 1931 Serial No. 584,194

1 Claim.

This invention relates to the production of cinematograph or other continuous film-positives of two (or more) colors by means of a central support of transparent film-material suitably 5 prepared with two adhesive substratums andA two (or more) photographically produced component images which have been printed from the front then applied to such substratums upon opposite sides of the transparent support, by first preparing the images each upon a temporary support of porous paper, and then transferring and cementing the two images to the adhesive substratums by pressure-contact assisted by moisture and with their printed faces in contact with the substratums, then drying out themoisture, and subsequently developing both images from the back or opposite faces simultaneously and removing and discarding the two temporary supports of paper, and is a modification of my prior Patent 1,873,674, dated August 23, 1932.

The objects of the invention are two fold, viz:- (1) To enable aV film to be produced with only one piece of transparent support or lm material, and with two relief images which are exposed from the back (and developed from the front) whilst on a temporary. support of porous paper from which they are subsequently transferred on the one central permanent transparent support back-to-back; and

(2) To provide a means or method by which absolutely accurate register of the two component images forming one picture can be ensured by a process of simultaneous registration and simultaneous transfer and cementing of the two images tothe one central transparent support.

, State of the art Many investigators have endeavored to produce a continuous strip of cinematograph filmr 4Q with a single support of transparent film and two differently colored colloid relief images upon opposite sides of the support in accurate register with each other. One method for producing such an article hitherto has been by using two thin supports, each sensitized upon one side, exposing each in printing through the back of its transparent support, developing the images from the unprinted front side of the film, and cementing the two supports together back-to-back either before or after developing to form a single film. Both strips were perforated before printing, and the perforations served as means of registration when printing and when cementing. The result l was technically satisfactory, but objections were made against this method upon the ground that two thin supports cost more to produce than one `support of equal thickness to the two combined.

registration this proved useless owing to unavoidable variation in length relatively to the different strips, owing to expansion and contraction during the Wet processes of transfer, and

therefore the original perforations made in all three bands were at this stage not the same pitch in the transparent final support and the temporary. supports. Therefore the original per- 7 forations made in the transparent support were useless as traction perforations because they did not place and locate the pictures correctly during projection.

The present invention is designed to overcome both objections, which it accomplishes by the following combination of methods and of construction:-

(A) The images are printed by exposure to light through negatives on to sensitized colloid carried upon the front face of paper strips or temporary supports, both of which have identical perforations and therefore accurately register with each other when laid face-to-face.

(B) The printed images upon the two temporary supports are then accurately registered opposite each other, exposed-face towards exposedface, by and upon a pair of registration sprockets, the .teeth of which exactly fit the perforations of the printed strips.

l(C) The printed images are then transferred to the two prepared adhesive surfaces of the transparent film which forms the permanent support and at this stage has no perforations transfer being effected by pressure when all three bands are clamped together.

(D) The printed images are then developed into relief images upon the permanent support of transparent film, the temporary paper supports being discarded in the process.

(E) Finally a series of traction perforations are made in the transparent support and the two-color positive is then complete.

The methods and means .of carrying out the invention'will now be described in fuller detail.

In carrying out the invention a double-width strip of porous paper is provided on its surface with a layer of suitable colloid such as soft gelatine, which is sensitized either with silver salts in the usual way as an emulsion or with bichromate salts applied by absorption.

Suitable coloring matter, preferably mordanted dye, is incorporated with the colloid during manufacture of the sensitized paper, in such manner that one half the width contains one color and the other half width contains the other color.

This double-width paper positive strip is printed with twoimages from a double-width, negative strip in known manner, either by contact or by projection.

The margins are given a separate or supplementary exposure in order to produce insoluble solid relief margins, as in my Patents 1,674,810 and 1,672,352, instead of the usual transparent and bare margins of other processes.

After printing, the strip is longitudinally divided into two single-width strips, and these are next laid upon the non-perforated singlewidth transparent film strip with one of the printed faces in contact with one of the substratums and the other printed face in contact with the other substratum. To ensure satisfactory contact the surfaces are dampened, the simplest way of producing `iust the right condition being to pass the strip of transparent support through a water bath (which may contain a very small proportion of acetic acid) and press the dry faces of the printed strips into contact with the damp adhesive substratums. After a suitable period of contact theadhesion of the two surfaces will be sufficiently firm and the triple band is then passed through a drying chamber until sufficiently dry.

When permanent adhesion of the printed faces of each transferred film to each substratum has been firmly established, the complete strip is submitted to the usual developing and other processes of treating to produce relief images. These operations will vary Iaccording to the type of sensitized surface used.

For example, if the colloid has been sensitized with bichromate, development is effected by hot water alone which is applied to the back of the printed image through the porous paper, the hot water dissolving all soft colloid and allowing the paper to come away from the film and be discarded entirely, and leaving behind firmly attached to the transparent support a series of relief images of insoluble colloid.

`If however, the sensitive colloid consists of a gelatine-silver emulsion it will, after printing, require the additional treatment of developing the silver image, then tanning the gelatine of the silver image in order to render it insoluble, and then total removal of the silver by means of the usual solvents; and when all these operations have been completed the film is treated with hot water to dissolve and remove the soft gelatine and leave behind relief images of insoluble colloid, as in the previous example.

The coloring matter is preferably incorporated with the colloid in the form of transparent mordanted dyes at the time of manufacturing the sensitive paper, and therefore when the images are converted into reliefs theyv will be readycolored reliefs. I

But the process can also be used with noncolored sensitive paper. in which 'case the reliefimages, when the developing and -treating processes have been completed, will be colorless and transparent. They are nextdyed to the right colors by application of suitable dyes in a dyeing machine fed by ductor rollers, and are afterwards mordanted to permanently fix the colors.

The feature of the invention which renders the successful carrying out of the process possible is the means of registration.

The invention will be described with reference to the accompanying drawings:-

Fig. l is a diagrammatic view of the apparatus for carrying out the invention.

Fig. 2 is a transverse section through the temporary supports and film strip.

Fig. 3 is a transverse section through the film positive.

Fig. 4 is a perspective view of non-perforated transparent celluloid film-strip showing an adhesive substratum upon each side.

Fig. 5 is a plan of porous paper strip and sensitized colloid layer and images thereon, after development.

Fig. 6 is a plan of the other similar strip (complementary lto the firs't strip) showing its images reversed with respect to those on the strip Fig. 5.

Fig. 7 is a very much magnified cross section showing the two paper temporary strips after development with their images of insoluble hardened and soluble non-hardened colored colloid represented by the darker shading, each image being of a different color, and with registration perforations in the extended margins of the paper strips, these being the first or temporary perforations which are used only for registration purposes in the printing and cementing operations. The sketch shows the two printed strips and the transparent celluloid strip in their relative positions before the printed images are cemented to the adhesive substratums of the transparent celluloid strip by pressure and moisture combined.

Fig. 8 is a very much magnified cross section showing the three parts of the lm after development and after cementing, but before its final development into relief, consisting of five layers all united together as one solid strip, and showing the registration perforations in the two paper temporary strips. 4

Fig. 9 shows the paper strips being removed from the nlm as it emerges from the hot water tank in which the developed images are converted into relief images attached upon both sides of the film support; the unfinished film of five layers having all been perforated together and therefore the two paper strips have two sets of perforations each, one for registration and the other for traction purposes.

Fig. l0 is an enlarged longitudinal section of the five layer unfinished film.

Fig. 11 shows a very much magnified cross section of the finished 2-color film-positive, comprising a central strip of transparent film having a series of traction perforations and a colloid relief image in blue-green permanently attached to one side, and another colloid relief image in orange-red permanently attached to the other side of the transparent celluloid support.

Fig. l2 is a very much magnified longitudinal section of a film having developed images on only one side before conversion into reliefs.

The transfer of the images is effected in the following way:-

The two images are first printed on a strip of double-width which is divided into two strips after printing and developing the images and before squeegeeing them to the transparent support and before conversion into reliefs. The Figs. 5 and 6 show the two strips after division wider than the finished film.

The two printed colloid images, whilst still attached to their paper supports, are first squeegeedinto contact with the twosticky adhesive faces of the central transparent film. They are' a drying chamber, from which it emerges dry'.

with all the layers firmly stuck together, the necessary time required to ensure perfect and permanent adhesion being provided by the length of travel through the drying chamber. This complete band, comprising five layers, is shown in magnified form in Figs. 9 and 10.

The solid band then passes 'through a perforating apparatus where the non-perforated central film y is perforated, the punches passing through the whole solid band, comprising all the aforesaid layers, including one film, two substratums, two printed colloid layers, and two paper supports. l

In a modification the film may be perforated before being sandwiched between the two paper strips and the two paper strips will then only have one set of registration perforations and the celluloid strip has one set of perforations for traction purposes.

The solid band then passes into a hot water tank. The hot water passes through the porous paper and dissolves some of the gelatine, so that the two papers no longer stick and'can therefore part company from the film, leaving the two printed images on the films instead of on the papers.

A suitable machine for registering, adhering and developing the strips and also for perforating is described in application Serial No. 366,743 filed May 28, 1929.

`In previously known and used methods of transferring two series of transfer images from two paper strips on to transparent film, it has been usual toA transfer them separatelyone after the other, and generally one over the other. In the period between transferring the first and the second series of images one series wouldalter in length compared with the other, owing to expansion or contraction of either the paper strip or the transparent strip, or both, with .the result that the two component images never registered accurately one over the other, and therefore when the picture was magnified upon the screen this difference, though slight in the prints, was greatly magnified, thus spoilingthe result.

In the present invention this serious defect is entirely eliminated, and accurate register en.- sured, by the hereinbefore described system of printing both sets of images simultaneously on the one double-width strip, and registering and transferring them simultaneously by two sets of registration devices which interlock as one common device only, and developing them simultaneously. l

'I'hese registering-devices may comprise a pair ot opposite placed wheels or drums having accurately cut sprocket teeth projecting from the surface of each drum, the two paper strips having each'a series of accurately punched perforations which are accurately spaced to the same pitch as the sprocket teeth.

To ensure the best results the teeth of one sprocket fit into holes in the other sprocket alternately, that is to say half the positions on each vsprocket comprise projecting teeth and the other half positions comprise holes placed in the alternate positions between them. Therefore one paper strip is always properly registered upon its own set of teeth and the other strip is likewise always properly registered upon its own set of teeth.

This pair of sprockets always` brings the pair of paper strips to the impression point where allthree strips are squeezed together. In effect they form a pair of smooth-faced drums or rollers between which the images to be transferred and the transparent support are gripped, the paper strips passing over or around one half of each of the said drums. The drums may, if desired, be rubber covered to provide slightly yielding pads. Y,

' The above described method of obtaining accu-n rate register requires that the pair. of paper strips" should be of greater width than the film and that they should have the registration perforations in the margins outside the width of the fil The same accurate registration can alg@ obtained with paper strips of the same widths the film strip and with the perforations in the usual margins vcommonly allowed in the film printing by employing two sprocket wheels the teeth of which do not themselves interlock but which are instead intergeared and driven from a common shaft through worm or bevel gearing. These sprocket wheels are arranged above the impression point, the latter being obtained by the first pair of a series of pairs of smooth rollers. Thus the contact of the two paper strips with the film strip does not commence until after the paper strips have passed the registering sprocket wheels instead of at the interlocking sprocket wheels in the earlier described method of obtaining accurate registration.

In both methods two paper strips are independently registered by independent sprockets. but in both methods these sprockets are under one common control either by being interlocked or intergeared, and the blank film is drawn or fed forward by the usual means, and is accurately guided upon each side to the impression point so that it is accurately placed in the right track at the period of impression. 12

The drawings (Fig. 1) show the process in principle but the complete mechanisms and modiflcations there of for carrying out the transfer are shown in detail in the machine described in my L specification Serial No. 564,360 filed September 22nd, 1931.

The transferring machine comprises a suitable reels, and with suitable feed sprockets or drums for supporting and feeding the: two paper strips 135 and the transparent strip 'and bringing them to the pressure rolls, after which the combined triple strip passes to developing and treating apparatus of any suitable known kind, but preferably to a machine such as described in my prior Patent No. '1,736,557 dated November 19, 1929.

The colors used in producing a film according to the invention are varied as required. For a two-color natural photograph one color will be 145. orange-red and the other blue-green. For a stereoscopic picture of the non-registering type one image will be red and the other green.

Monochrome pictures comprising images on one side only of the film support may be transferred and treated in the same way, as shown in Fig. 12.

If four-color films are required the operations are repeated by transferring a second set of image-components on to and superimposed upon the rst set, the colors in that case being preferably red, green, violet and orange.

In my Patents Nos. 1,250,713 and 1,173,898 and 1,173,899 I have described a process for manufacturing a color lm comprising a central transparentA support with a differently-colored image upon each side, and which is produced by sensitizing the transparent support itself upon both sides and interposing a light-obstructing layer between the support and sensitized layers, and each sensitized layer is printed by exposure from its face side whilst forming an integral part of the lrn.

In the present invention the central transparent support is plain and not sensitized, there are no light-obstructing layers, the sensitive layers are carried before printing upon separate temporary paper supports, they are each printed from the face side of the sensitized layer, and after printing the sensitized layers are cemented by their ,printed faces to the central transparent support so that the printed sides are inwards,

and are finally developed into reliefs from the back of each print through the porous paper;

therefore the former backs of each print become the outside fronts of the completed nlm (the images having been 'inverted in the process).

The negatives used in printing have one image of the pair reversed in relation to the other image.

What I claim as my invention and desire to protect by Letters Patent is A method for the production of cinematograph 111m positives from partial images carried on separate porous paper supports comprising registering the paper supports one on each side of a nonperforated llm base, simultaneously transferring the images from the paper supports on to each side of the lm base by pressure contact, passing the combined band firstly through a drying chamber, secondly through a perforating machine which punches traction perfor-ations therein and thirdly through a hot water bath which loosens the porous paper from the film strip and nally stripping the porous paper therefrom to leave a film strip having relief images on each side in accurate register.

J OHN EDWARD THORNTON.

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