US2111759A

US2111759A - Film developing machine

Info

Publication number: US2111759A
Application number: US742203A
Authority: US
Inventors: William L Douden
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1934-08-31
Filing date: 1934-08-31
Publication date: 1938-03-22
Anticipated expiration: 1955-03-22

Description

March 22, 19381. 'w DOUDEN 7 2,111,759

FILM DEVELOPING MACHINE Filed Aug. 31, 1934 2 Sheets-Sheet l 0 ISnnentor VVilliam L. Douala,

' attorney a.rcl1122,1938. D DE 2,111,759;

FILM DEVELOPING MACHINE Filed Aug. 31, 1934 2 Sheets-Sheet 2 "nmlmmmmm Z5 llllllllll ll i mm I I 7 ATTORNEY Patented Mar. 22, 1938 FIIM DEVELQPIN G MACHINE William L. Douden, New York, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application August 31,

6 Claims.

The present invention relates to an improvement in film developing machines, and more particularly to an improvement in the type of such machines used in the continuous high-speed development of motion picture films. The present invention also involves a novel method of developing films, included in the operation of such machines but which can be performed independently thereof and which is claimed in my divisional application Serial No. 117,350, filed December 23,1936. I

It has heretofore been customary in the art to pass motion picture film through a series of tanks or tubes of developing fluids under the control of driving sprockets or rolls, the film being passed downwardly into the various fluids, upwardly therefrom,- and again downwardly from the air,

into fluid until the termination of the process.

Such procedure is particularly objectionable in the case of motion picture film, which is perfo rated at the edges with" sprocket holes, as the sprocket holes retain air and carry it into the developer. All photographic developers are notoriously subject to oxidation, since; from their very nature, they are required to be powerful (although controllable) reducing agents. As a consequence, the carrying of air and oxygen into the developer and other baths by the film shortens the life of the developer, and, due to the irregular oxidation by the air bubbles, tends to produce irregular development resulting ,in spots, and streaks on the fllm. This is particularly annoying in the case of combined sound and picture film, where the spots and streaks produce loud pops and bangs in the sound reproduction from the photographic sound track.

One object of the present invention is to provide a developing machine which will prevent the introduction of air into any of the fluid baths used in treating the film.

Another object of my invention is the provision of a developing machine which eliminates air or gas bubbles from the fluid baths.

Another object of my invention is to provide a developing machine which treats the film at less than atmospheric pressure.

Another object of my invention-is. to provide a developing machine which is substantially proof against leakage.

Another objectof my invention is to provide such a machine which can be readily cleaned. Other and ancillary objects of my invention will be apparent to those skilled in the art from an inspection of the accompanying drawings and reading of the accompanying specification.

1934, Serial No. 742,203

In the drawings: A

Figure 1 shows a longitudinal section of a preferred form" of my invention;

Figure 2 shows a second form of my invention;

Figure 3 shows a transverse section thereof, and 5 Figure 4 shows a preferred detail applicable to both of the above forms: 7

As will be-apparent from a casual inspection of these drawings, one of the major features of my invention is the complete processing of the film 10 in a partial or complete toricellian vacuum, where the highest pressure to which the film is subjected is approximately that of the atmosphere and the lowest pressure approximates that of the vapor pressure of the developer at the temperature of development.

Referring first to Fig. 1: The film F passes into the apparatus, for example, from left to right as indicated over an idler roller and into the fluid D contained within the tank I, and the level of which is maintained by the inlet pipe b which the supply is provided from the supply t I nk.

T e film' passes around an appropriately-bearinged corrosion-proof idler roller 2' and upwardly into the developing tube 3. This developing tube may be made of any desired material, but for negative film I prefer to make it of- Monel metal or hard rubber, which are opaque and corrosionresisting; while for positive film I prefer to make it of astrong corrosion-resisting glass such, for example, as that known under the trade name of Pyrex in order to permit inspection of the film during development, as the positive film' may be safely handled in a relatively strong yellow light.

Near the top of the tube the film passes over,35 an idler roller 4 which is supported from a float 5 in the fluid. It will be apparent that, since the :roller 4 is supported by the float 5, the film can never be supported above the fluid level in the tube. The float may preferably be made of par- 40 afiined: cork or balsa wood, or hollow, and of Monel metal, hard rugber, or plated copper or brass, but.

tracting proper quantities of fluid from the tubes and maintaining an appropriate vacuum.

An extraction pipe 6 is provided, preferably connected to a pump and extraction system of any known or desired type withdrawing a predetermined quantity of fluidper unit of time or influx, and preferably irrespective of the gaseous content thereof; i. e., such as gas-well clearingpumps and the like.

Above the influx level of .the pipe 6, there is preferably provided a second effusion pipe I connected to a second manifold tand which, in turn, is connected to a second pumping system of known type adapted and adjusted to maintain a predetermined pressure difference between atmospheric pressure and the exhaust pressure, in order to maintain a constant fluid level. Such a system may be comprised, for example, of a relatively large capacity exhaust pump and either a control or a relief valve governed by atmospheric pressure to maintain a constant pressure difference; the large capacity of the exhaust pump being desired to provide for the initial elimination of dissolved gases, and such gases 'as might be accidentally introduced.

ment of the film.

The film passes downwardly through the tube 3 to the idler 2, which is identical with 2', and thence upwardly to the driving sprocket I0 which forms of my invention inthe form of a hinged trough. The trough is preferably supported at one side by the bracket 2| and pivoted at 22, and is supported, at the other side by a movable member 23 which fits beneath a catch 24.

When it is desired to clean the apparatus, the trough I is raised slightly to release the member 23 from the catch 24, the member 23 is pulled is illustrated as slightly above the fluid level, for

reasons hereinafter described. In order to secure the simple film drive shown in Fig. 4 wherein the sprocket shafts 26 are driven through a helical gear from the line shaft 21, the driving sprockets are shown as located above the..,fluid level. It will be, apparent, however, that'if other driving means. are substituted such, for example, as corrosion resisting chains or gears, the-sprockets may be immersed in the fluid and the film kept continually immersed during'the entire process.

In the successive elements of the apparatus, the corresponding parts are designated by identical reference numerals 2 to ill inclusive, and the pipes 6 and l are respectively connected to the manifolds 8 and 9.

It is apparent that if fluids of different density are to be used for the same time,or fluids of incommensurate density for incommensurate units of,time, the manifolds must be corre-' spondingly subdivided and controlled, or the lengths of the tubes selected or controlled, or

' both.

backwardly and the trough l is permitted to hang from the pivot 22, thereby emptying its contents into a trough 25 formed in the floor of the 'room housing the apparatus and permitting a thorough scrubbing not only of the trough l but of the tubes or tanks 3.

Having now described my invention, I claim:

1. In a developing machine, a liquid receptacle, and a film treating chamber closed at its upper end and extending upwardly therefrom and adaptedto contain a liquid maintained by atmospheric pressure, whereby film may be passed continuously through the region of reduced pressure at the upper end of said receptacle.

2. A developing machine comprising a liquid treating container, means for immersing the lower end thereof in liquid, and means for producing a pressure below that of the atmosphere within treating container, means for immersing the lower end thereof in liquid, means for withdrawing liquid from the upper end thereof, and means for producing a pressure below that of the atmosphere within the upper end thereof, whereby film may be passed continuously through the region of reduced pressure at the upper end of said container.

4. A developing machine comprising a receptacle for liquids having its lower end open and its upper end closed to the surrounding atmosphere, means for passing film through said receptacle, and means for maintaining liquid within {I'he fluid level maybe controlled in any appropriate manner either by control of the exhaust apparatus or by the provision of an exterior tank as shown in 'sig. 1, and this fluid level is generally indicated at 3!, the film being withdrawn through an appropriate trap 32. The inlet pipe is the same as that shown in Fig. 1.

As shown in Fig.3, the film may be threaded said receptacle, whereby film may be passed continuously through the region of reduced pressure at the upper end of said receptacle.

5. A developing machine comprising an inverted tank, a trough therebeneath and covering the lower end thereof for maintaining fluid therein, means supporting said trough in such a manner that it is removable from said covering position, and means for passing a strip of film through said trough and tank, whereby fllm may be passed continuously through the region of reduced pressure at the upper end of said tank.

6. A developing machine comprising a liquid treating chamber maintained at less than atmospheric pressure, and means including a liquid seal for passing film therethrough, whereby film may be passed continuously through the region of reduced pressure at the upper end of said chamber.

WILLIAM L. DOUDEN.