US1580115A - Color cinematography - Google Patents

Description

pril 13 1926. 1,580,115

P. n. BREw's-rER COLOR CINEMATOGRAPHY Original Filed DSO- 28, 191 8 4 Sheets-Sheet 1 lll-Llllbllllllli ll'lllllll-lllllllllllm lllmlllllllllwm a-mm April 13 1926. 1,580,115 v P. D. BREwsTER COLOR CINEMATOGRAPHY original Filed Dec. 28, 1918 4 sheets-sheet 2 6 s 0K2 02 0 w n v: QS/v 1, m D 0 S l. m O w D D D D D D D D @D D E D D s 2 2 2 4 @D fm2, tu A@ a 05 W/ m 3g 2 d 2 f m w D E E D D D D E D C 6 a ma g EM 2 Hmm o o 0% ai 1 9 .cm Z n n @D D D E D D D D@ D D E E D amm. ,\0\ m. 2 Mw mmmommmommmomm DDEE @DED DDQ@ @DE @n.mnmnnmnmm w w i a, a, 3, D D D D n DE@ @D D D D D D .a/w w M w 1 B A April 13 1926.

P. D. BREWSTER COLOR CINEMATOGRAPHY Original Filed D 4 Sheets-Sheet 4 Patented Apr. 13, 1926.

UNITED STATES 1,580,115 PATSEN orrlce.

PEBCY D. BBEWSTEB, OF EVAST ORANGE, NEW JERSEY.

COLOR CINEMATOGBAPEY.

Application led December 28, 1918, Serial No. 268,673. Renewed July 16, 1925.

a full, clear, and exact description.

My present invention relates to the construction of cameras and printers for color cinematography in which the color records are made on separate negative films and printed on opposite sides of a double coated positive and comprises means for securing vregistry between the images printed on the two sides of the positive film.

My invention consists broadly in perforating the negative films while they are at rest in their film gates and to register the negative films when printing the positive by means of these perforations, and is an improvement over myI co-pending application, Ser. No. 224,110 filed March 23, 1918.

I am aware that cameras for black and white have been made in which a single lm was perforated in the camera and registry with the positive when printing was secured by those perforations, and that it has been suggested in color photography to ez-:pose the separate films and to print by contact on two sides of a double coated positive film from the two negative films obtained, but this process has been a failure to date, due to insuperable difficulties in registration and the object of YUthis invention is to' provide means for securing the necessary degree of accuracy in registration.

Registration between the images on the two sides of the positive film should be sufficiently accurate that when the pictures are projected under normal conditions, no separation, fringing or banding of the colors about an object will be noticeable to the ordinary observer.

As the best lenses today have a .circle of confusion of about one five hundredths of an inch and as the silver grains in the negative film will not record any sharper image, it is apparentthat if the error in registry between the two imagesV does not exceed that amount the picture on the screen will be satisfactory.

My invention is illustrated in the accompanying drawings of which Fig. 1 is a horizontai section through the camera; Fig. 2

is a side elevation partly in section; Fig. 3 is a plan of the light splitting surface of the prism; Fig. 4 -is an elevation of the perforating plate; Fig. 5 is an enlarged section through the punch plate; Fig. Gis a plan view of the punch also double size;

Figs. 7 to 10 illustrate different arrangements of the punches; Figs. 11 to 16 illusa simultaneous-printer; Fig. 25 is a plan of the electric controlling commutator; Fig. 26 1s a diagram showing the contacts on the commutator; Fig. 27 is' a plan of the perforations superposed for printing; Fig. 28 is a side elevation of an optical printer.

Referring to the camera in Fig. 1, the lens 1 is'mounted on the front board 2, which is adapted to be moved for focusing on the base 3 between the guides 4, 4 by means of rack 5 and pinion 6 (Fig. 2).

The light rays from the lens 1 enter the splitting prism 7-8 mounted behind the lens and are divided into two color-groups. The surface 9 of prism 7 is adapted to transmit a portion of the light rays reaching it and to reflect a portion. This surface, Fig. 3, may be partly coated with bands of silver and cemented to the adjoining prism 8.

The transmitted portion of the light rays pass through the red filter 10 and are recorded on film 11 in the film gate while the reflected light rays pass through the green filter 12 and are recorded on film 13, to produce a red color-value negative image on film 11 and a corresponding green colorvalue image on film 13.

The films 11 and 13, as illustrated, are at right angles to each other, but they may be mounted in an relative position that is in accordance wit the angle of the light splitting prisms.

The films may be both panchromatic or one may be specially sensitized for light of the green color group by pinaverdol, for example and the other film sensitized for the red color group with pinacyanol. In case the films are specially sensitized I sometimes prefer to use in front of the fil-m sensitized for green a yellow filter such as K 2 or K-3, which sufficiently reduces the action on the film of the blue or violet light rays. This type of filter is faster than the green filters and thereby permits a reduction in timev of exposure. This yellow filter is of course not complementary to the red filter. The two films may bey fed through the exposure fields of the camera by any of the well known intermittent feeding mec-'hanisms, such as the Lumire. or Geneva movements, the latter being illustrated. The film 11, being fed by means of the sprocket 14, attached to the star wheel 15 and operated by the pin 'wheel 16 Von shaft'17, which also drives the film feeding mecha.- nism of film 13 through the miter gears 18 and shaft 23.

The cams 19 and 2O are mounted on the Shafts 17 and 23 respectively, and are arnanged to operate the rocker arms 21 and 22.

Film punches 24, 24 are mounted in guides 25, 25 respectively, so as to perforate the films 11- and 13 preferably inthe margin. Springs 26, 26 are mounted to act between the guides and the enlarged hea-ds of the punches 24, 24 and tend to force the heads of the punches against the rocker arms and, in turn, to hold the arms against the controlling cam.

The cams are preferably so, time-d that when the film has been fed down one space Vby the sprockets, the punches vcut one or more perforations in each film.

The film used in the camera may be without perforatio-ns and fed b-y means of wellknown friction feed mechanisms, but I prefer to use film perforated with one or more perforations missing in each series of four, as shown in Fig. 11. I then prefer to arrange the punches so they will cut the master perforations 27, 27, Fig. l2, in .the space between the feed perforations 28, 28. The

film being fed through the camera by means of sprockets on which every fourth tooth is missing.

As shown in Fig. 12, these master perforations 27, 27 are round, but they may be any shape desired, or made to conform to the present film standard as sho-wn by perforations 29, 29, Fig. 13. It is not essential that these perforations be equally spaced between the feed perforation 28, 28 as indicated in Fig. 12.

In ease the flattened perforations are used, it is essential that the flat portions of each of the punches 24, 24 should be parallel. I

vprovide means for adjusting the punches y mounting a pin or key 30 arranged to move in a slot 31, in the bushing 32 in the guide 25. The key is fitted without shake in the slot and the whole bushing with the punch may be turned in relation to the guide, being secured .by the screws 33, 33

to pa-ssbetween the die plate 34 and the guide 25, beingv held against the die plate.`

by means of thepressure plate 38, by the action of the springs .39, 39. v

In my invention I prefer that the punches perforate the films before exposure and remain in place during the exposure and are withdrawn after the exposure and before the films are moved, but the film may be perforated and the punches withdrawn before the exposure or the film may be perforated during or after the exposure, without departing from my inventio- One of the punches, or sets of punches, are set arbitrarily to engage the film atv the proper point, preferably alongside of the. image and this relation to the image is accepte as a standard and t-he posit-ion of the image on the other film in relation to its master perforat-ions is adjusted to. conform to the relation of the first film as a standard.

My invention provides two means by which this registrycan be secured; one by movinoone image in relation to the other and tie second, by adjusting Athe position of the punches controlling one of the. films.

The optical adjustment is secured by mounting the prisms 7-9 on the Aplate 40 adapted to ti rn in the base 3 on pin 41, controlled by t ie action offthe eapstan screw 42, between Stops 43, 43.' The clearance holes for the screws 44, 44 in4 plate 40 are sufficiently large. to permit the necessary slight rotation of the pla-te for adjustment. By adjusting the capstan screw the image on the film 20 is moved in azimuth in relation to the imiage on the other film. Adjustments in altitude are made'by inserting packing or .shims under one side of the prism wl1icl1.isl1eld in place by spring clamps 45, 45. Or the plate 40 may bc tapped out on either side to receive screws adaptedv .to bear against the prisms and tilt them in either direction desired. Any means of adjust-ment, single or universal. maybe used for controlling the position of the splitting prisms Vwithout departing from the spirit .of my invention.

In a well built camera. of this type vonlyv very small adjustments, possibly a few hundredths of an inch, are necessary to secure registry and I have found by practical experience that shims 46, 46 fittlng between the punch guides 25, Fig. 4, ,and the film gate provide very satisfactory means of Securing these adjustments. My practise has been to perforate the two negative films in the camera and to register them by means of pins through the Iperforations and to measure, under a microscope, the error in registry vertically and horizontally in thousandths of an inch and to alter the thickness of the shims controlling one punch guide to correct the errors thus determined.

I sometimes prefer to use shims 46, 46 between one side and top of the film gate and the guide and to insert the screws 47, 47

through the other side of the film gate to.

force the guide against the shims. By altering the thickness of the shims the error is quickly and accurately corrected. The screws 48, 48 pass through clearance holes in the guides 25, 25 and are tapped in the film gate and may be loosened to permit the necessary adjustments to the guides.

The shutter 49, adapted to protect the films from the action of light when the films are moving is operated by gears 50 and 51 from shaft 23.

Particularly if punches cutting the master perforations in the negative are shaped similarly to the perforations inthe positive, I prefer to locate the punches controlling the films exactly similarly spaced in regard to the individual images they control or the perforations are displaced in regard to the location of the image by the exact distance between one or more perforations in the positive as is illustrated by the Figures 7 and 8. ln this case one negative would be registered on the positive by means of its master perforation and a perforation suitable for registry purposes in the positive, While the negative film on the other side is registered by its master perforation and a different registry perforation in the positive.

if desired, the two punches Fig. 9 may he set at different levels preferably separated by a multiple of the distance between the perforations in the positive or both punches may be set to perforate in one margin of the film as shown in Fig. 10, or a single hole may be punched in each of the films and by means for contactingagainst the sides of the film used to secure proper registry Without departing from my invention.

Film may be perforated in the camera, as shown in Fig. 14, withmaster perforations 52, 52 controlling the position of the images and'before printing, be reperforated as in Fig. 15, using the master perforations as a guide for the pilot pins in the reperforator and cutting registry perforations 53, 53, which preferably are located at equal distances from the images, or are displaced by a distance the multiple of the distance between perforations inthe positive, and which conform to the standard of perforations used in the positive. I prefer that the three films when printing may be registered by passing properly shaped registry pins through the registry perforations 53, 53 in the two negative films and any registry perforations in the positive.

Fig. 16 illustrates a negative film in which the holes 52, 52 perforated in the camera are on different levels as well as the registry perforations 53, 53 cut in the reperforator, but which conform to the standard of perforation in the positive and can be readily registered. The camera perforations 52, 52 may be located between the images near the center of the film and these holes may be used to guide the pilot pins in reperforatmg.

holes 28, 28, may be used in a camera adapted to advance the film five perforations for every exposure. Every fifth perforation in the margin is omitted and while in the camera a single master perforation 29a Fig. 18 is cut in the film, preferably near the center while at rest for each exposure and wwhen the film is moved forward for the next exposure a pin, preferably tapered is entered into the perforation to hold it in exact place before the next perforation is cut in the film. Each image is thereby fixed in place b its relation to the perforation above and elow it. Before printing or even before development the registry perforations 30, Fig. 19, preferably shaped to conform to the perforation standard of the positive, are cut in the margin by a perforator, their location being controlled by pilot pins entering the perforations 29, 29a above and be- Film perforated, as shown in Fig. 17, with low the picture. The film may then be registered directly with the positive by pins through its registry master perforation and a registry perforation in the positive.

By this method any change in size `of the negative, due to shrinkage in developing, fixing and drying the films after exposure, avoided and the negative and positive perforation standards are exactly equal.

Negative film perforated in the camera with round holes or any special shape, as the holes 27, 27 shown in Fig. 12, between successive groups of feed- perforations 28, 28, Fig. 11, may be registered on positive film perforated as shown in Fig. 20 with the specially shaped perforations 28a P28, between the successive groups of standar perforations 28, 28, and after. printing (before development if desired) the positive may be reperforated with the standard perforations cutting away the original registry perforation 28, If desired only the holes v28?, 28EL may be perforated before or during printing and all the lstandard perforations cut in afterward. "-Ifthe negative master perforations 27, 27, and the registry perforations 28u are larger than the standlio ard perforations28 provided in the' positive for feeding thelatter through the projecting machine, the positive perforations 28, .28a may be left as they are instead of being reperforated and tlre positive film may then be fed through the projector by the remaining perforations 28, 28. In short, it is only when the registry perforations 28a in the positive lare not large enough to receive ,the feed-claws or teeth of the feed-mechanism of the projecting machine that the registry perforations need to be re-cut. n

Using the type of perforation'in which the registry master perforation in the negative conform to the positive standards of perforation it is not neces3ary that the images` on both sides of the positive film should be simultaneously printed, but the4 film may be printed in a type of printer illustrated diagrammatically in Fig. y22. The double 'coatedpositive film 84 is fed from roll 85 in contact with the negative film 89 from roll 90 through the printing aper- A ture and registered by pins 93 and'printed aio 'the printer by means of the reciprocating by light 92, the films being moved intermittently by sprocket 86 and the negative film wound up on spool 91. The positive film 84 continuing along in contact on the other side with the other color record nega'- tive 94, fed from roll 95 and printed by light 96 when located in the printing aperture by pins 97, both films being fed intermittently y sprocket 87 and Wound up on spools 95 and 88 respectively.

I prefer to print the two sides of the positive simultaneously from the two negatives in the printer illustrated in Figs.` 23 to 26 inclusive. The negative 11, the double coated positive film 54 and the other negative film 13 are fed or moved intermittently through feed pins 55 mounted on the cross head 56,

the movements of which are controlled by the rod guides 57, 57. The cross head'is operated by the rod 58 sliding in the oscillating guide 59, which turns on shaft 6() and is drlven by the sliding connecting rod 61 from the crank pin 62, mounted on disk 63 attached to driving shaft 64. Solenoids A, A controlled vby the commutator 25, Fig. 19, are adapted to draw inl the iron or magnetic portion 66, 66 of the feed pins 55, 55 against the action of springs 67. These feed pins tapered at their tips, are adapted to enter the perforations of all three films and to feed or move them one ima'g space and are adjusted so as to leave the registry perforations of the two negative films and a pair 'of perforations in the positive films sufficiently superposed to allow the entrance of the suitably tapered registry pins l68, 68 alongside of the exposing aperture 69, open top and bottom in the printer. Suitable lights are arranged above and below the films for exposing the positive film, and shutter mechanisms, operating in harmony, with the film feeding mechanism, are provided to protect the film from the action of light .when it is moving. The registry pins 68, 68 are operated by solenoids C, C, controlled from the commutator 65, against the action of the springs 7.0, 70. The films are fed through the printer under light tension When moving or when the registry pins are entering but, just before exposure, the pressure plate, adapted to fit over the films about the aperture plate, and attached to covers in the solenoids D, D, is drawn down firmly against the lower plate of the film gate and the films are forced firmly into contact with each other while print-ing.

If the negative films are perforated With round holes, 23, 27, Fig. 12, slnaller in size than the perforations in the positive or, in fact, if the negative perforations are not similar in shape to the positive perforations, the registry pins, while locating and superposing the two negatives have no control of the position of the images printed on the positive film. Under these conditions each pair of images on the tvvosides of the positive will register but may not be similarly spaced in relation to the sides of the positive film or the pe forations, the result being that the picture Willize very unsteady or weave When projected on the screen. I overcome this condition in my invention by providing pressure shoes 71, 7l to maintain 'a varying pressure on the positive film only. These shoes are pressed against the film by means of the fiat spreader springs 72, 72. The core 73 in the solenoid B is forced against the spreader spring 72 constantly by fiat spring 74, which is adapted to hold the film under the desired tension when being fed, while the solenoid B is adapted t-o grip the film and hold it firmly after the film has been fed one image space and before the registry pins start to enter and possibly move the positive film by friction from the two negative films being moved'slightly in being superposed by the registry pins. ,I also prefer to provide suitable side guides in contact with the positive to prevent any side displacements ofthe positive.

-The commutator drum 65, operated in synchronism with the film feeding mechanism, is mounted in frame 75 and is adapted to hold the four brushes A, B, C and D against the drum. Metal segments 76, 77,

78 and 79 on the drum properly connected to an electric circuit are adapted to make contacts at the proper times with the'brushes A. B, C and D, which are connected to the similarly lettered solenoids. The duration of the contacts With the brushes, and consequently the action of the solenoids is shown by the diagram in Fig. 20. The solenoids A, A are energized while the feeding pins are moving the film, the solenoid B, B are lll) energized after the film hasstopped feeding until nearly ready for the next feeding movement; the solenoids C', C are energized y pins 84.

after the film hasrf been gripped by the solenoid B, B and 'while the exposure has been made and theIsolenoids D, D are energized after the registering pins have entered the film perforations. Anyv suitable mechanical movements may be substituted for the solenoids illustrated, without departing from my invention.

If desired all the images can be printed on one side of the positive film in a single-light printer and then the positive film turned over and run through the printer again with the other negative film and the images printcd on the other side of the fihn.

Negative film made according to my invention either with round or standard shaped perforation may be printed in the optical printer illustrated in Fig. 28, in which one of the negative films is drawn intermittently down through the film gate 80 and the registry pin 8l used to properly locate the images in the film gate by means of a mechanism similar to that described in the camera. The positive film 82 is fed intermittently up through film gate 83 by suitable means, the position of the images on the positive film being located by the registry A suitable source of light is arranged to illuminate the negat-ive film 11,

and a shutter arranged to protect the posi-v tive film from the action of light when it is in motion. After the seriesof images on one side of the film are printed from one negative. film, the positive film is turned over and again fed through the printer with the other negative film; if the positive is not reversed one of the negative films must be printed through the Celluloid. A

It is to be understood that, according to my invention, it is immaterial as to the optical system employed for exposing the negative films, whether a single or double lens system be used, whether the two negatives are made simultaneously or consecutively and whether the two films run horizontally or vertically through the camera.

In place of the two separate films, an extra wide film may be used and the negative images exposed side by side, perfo-rations being punched to control the position of the images on the film. After exposure, if desired, these films may be vcut apart and used. as two separate films or the images on the double width film first on one side of the positive and then on the other. l

For three color cinematography three separate films may be used, the position ofthe images on the three films being controlled by suitable perforations cut in the camera and the films printed in registry by means 1 of these perforations, 'i

I prefer to use on all finished positive prints the generally accepted standard for perforating so the film may be used in any projector without difficulty, but if I intend perforating the negative with holes that are adapted to register with the positive perforations, I prefer to use in a negative special perforations of standard shape which .are larger and spaced farther apart (across the film) than the standard size and separation to compensate for the shrinkage of the negative film in developing and drying. This shrinkage is usually considered to be about one per cent or slightly over, so that the negative perforations are preferably made about one per cent larger and further separated than the positive.

I claim- 1. In the art of color-cinematography, the improvement comprising passing a plurality of negative films' step by step through exposure fields, dividing the light rays from the object to be photographed into aplurality of color-groups and projecting the colorgroups upon said negative films to form separate series of color-value negative images on the respective films, perforating the films, at definitely located points with respect to the images projected thereon, while the films are at rest for exposure, to produce master perforations, re-perforating the films with said master perforations as guides to produce registry perforations, and printing the several series of 'color-value negative images on opposite sides of a positive film provided with registry perforations conforming to the registry perforations in .the

negatives and iny printing, registering registry perforations in one film with registry perforations in another, whereby the images printed on one side of the positive are made to register witli'those on the other side. .i

2. In the art of color cinematography, the improvement comprising dividing the light rays from an object to be photographed into color-groups and projecting the same upon separate negative films to produce separate color-value negatives, perforating the negative films at definitely located points relative to the imagesY projected thereupon whilethe films are in position for exposure to produce master perforat-ions therein, re-perforating the negative films with the master perforations as guides to produce registry perforations, and printing the negative images from one of said negative films upon one side of a perforated positive film and the negative images from another of said negative films upon the other side, of the positive film; and in printing, inserting pilot pins into registry perforations in the positive and registry per-v forations in the negative to produce registry of the images printed on the two sides of the positive.

3. In the lart of color cinematography, the improvement comprising passing step-bystep through'separate exposure fields negative films each having along an edge a series of 4spaced groups of feed-perforations, dividing the light rays from the object to be photographed into color-groups and projecting the same upon the respective negative films while the latter are at rest to produce thereon separate series of negative images, and While the films are at rest perforating the same between successive groups of feed perforations to produce master penforations at definitely located points relative to the respective images projected thereon; re-perforating the negative lilms with the master perforations as guides to produce registry perforations; providing a positive film sensitized on both sides, having in an edge a series of spaced groups of feed-perforations and registry perforations between successive groups of feed-perforations, printing the images of one negative film upon one side of the positive and the images of another negative' film upon the other side of the positive, and in printing, inserting pilot pins into the registry perforations 111 at least two films whereby the images printed on one side of the positive are made to reg1ster with the respective images on the other side.

In testimony whereof I afiix my signature;

PERCY D. BREwsTER.

'Certcatoffcorreetiom .y p It is .herebyl certified that in Letters Patent No. 1,586,115, granted `pril 13,1926,y

upon the application of Percy D. Brewster, of EastOrange, Newieiseyyfor'au p C lo 4Cinemato'ra, hy errors appear in the printed specifica# Improvement m o r A D agel line 14, strike out the word..master orrection as follows: y L v alzdl flgltlllilliid perforation 7 Yread perforqtz'om; and that the said Letters Patent n .should be read-with thesecorrections therem recordof the case in the Patent Office this 11th day -of yMay,

I Signed and sealed [SEAL] Afl D.l i926, i l l J.` MOORE,

that the'samemay conform vto the:`

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