US1170674A - Film-cartridge. - Google Patents

Description

@aATES PATENT OFFICE.

F ELGCHESTER, NEW YORK, ASSIGNR T0 EASTMAN KODAK .7, DE GHEETER, NEW YORK, A C QRPORATION OE N'IE"YEK.`

FILM-CARTRIDGE. f

Specification of Letters Patent. "p Patented Feb. 8, 1916.

application filed September 25, 1231-2.4 Serial N o. 722,165.

part of this s)ecificatilni.,` and to the refercited thereon.

r y present ation relates to photography andA more particularly to photo- ,n iev film rolls or ce.i for its object to provide a construction of such devices whereby as the' ,film and its paper or other protective backing is drawn fromA one spool Aonto the other during exposare in the camera it will be necessarily drawn taut and true occupy a flat posi.- tion in the focal plane.

To these and other ends the invention' consiste in certain improvements and combinations of parts all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.

ln tne drawing: Figure l is a perspective view of a photographic film roll constructed in 'accordance with and illustrating one embodiment of my invention, the outer end thereof being `pmt-ially unrolled; Fig. 2 is an elevation thereof, and Fig. 3 is a section through a camera in which the film roll is being" unwound from a feedspool onto a Winding spool during vthe process of exposure.

Similar reference numerals throughout the several ligures indicate the same parts.

As to its general features, the cartridge of the present invention may be constructed as usual, that is, to embody a roll preferably Wound about a suitable spool or center i and consisting or a strip of flexible film or sensitized material 2 and a protective backing strip usually of black paper superposed th ereon. the backing being slightly wider than the film strip and quite a little ger. The outer end of the film is attached to the backing in any suitable manner by a pastor and beyond this point 'of attachment enl of the backing conlution and final covf a meansof atspool.

g e' iment ridges, and it has inasmuch as the lm strip is Wound inside of the backing strip, though both are Wound together, the convolutions of the backing .strip arealways longer than the corresponding convolutions of the film strip being of a greater circumference. In other Words, a revolution of thewinding spool 6 (Fig. 3) takes up a greater length of backing than it does film. The result is that in any film roll of this kind there is a relative creeping movement of the `film with respect to the backing so that though the backing be taut the film will be loose and have a tendency to sag or bulge. This may be compensated for, of course, when the end of the unrolled film is reached either by leaving such end free in the beginning and vattaching it after unrolling or by providing a sliding or adjustable connection between the two.l However, the damage is done during the process of unrolling as the film is exposed at that time and if it bulges or buckles all parts of the negative will notbe in focus even though the backing is drawn taut by reason of the fact that it is the backing that is under tension from the Winding roll and which is causing the rotation ofthe feed roll. In the practice of my present invention I therefore transfer the Winding tension from the backing to the hlm itself. 'To this end, I provide the backing at a point intermediate the ends of the film strips and preferably near the outer or attached end so that it Will follow the lm end upon the lWinding spool7 with an extensible portion 7 that yields sufficiently to prevent the backing from assuming the strain further than its point of attachment to the film and which transfers the strain to the latter as Will be seen from inspection of Fig. 3. The extensible portion 7 of the backing may be 'conveniently and inexpensively formed by simply creasing the backing strip transversely and folding over a double prtion thereof in a manner clearly shown by the drawings. When so formed, it will Wind close on the roll and yet give ample additional length to the backing to overcome the shortening of the latter relatively to the filmr as above explained. l

0f course, differences either Way in theV relative thicknesses of the film and kbacking either aggrav or relieve the tendencies pointed out to a greater or less extent but they are very much aggravated when the convolutions on the Winding spoel are of spool. Thus, AWere it not for the extensible' portion 7 the backing Would be drawn tight and the slack in tb film Would increase, this effect being-cumulative though to a decreas i ing degree up to the time that the two rolls become of the same size, which is one of the reasons that I prefer to locate the extensible portion of the backing near the advancing or outer end of the film. After the Winding, roll becomes the larger and the feed roll the smaller a reverse action takes place which tends to take up some of the looseness 1n 'the .ilm but as far as the tighteningA of the inner end of the backing strip is concerned, the slipping of the last convolutions on the feed spool can usually be relied upon to take care of this.

l claim as my invention:

l. As an article of manufacture, an unn the same convolution v exposed photographic lm cartridge embodying a backing strip, and a film strip having one end attached thereto, the backing strip being provided, intermediate the ends of the film strip, with a relatively easily longitudinally expansible section.

2. As an article of manufacture, a. photographic film cartridge .embodying a baklng` strip and a film strip having one `end attached thereto, the backing stripbeing pmvided with an extensible portion at a point intermediate the ends of the film stri formed by a doubled crease or fold ma e transversely of the backing strip.

3. As an article of manufacture, an unexposed photographic film cartridge embodying a backing strip and alilm strip Wound together to form a roll with the backingstrip outside, the outer end of thelm strip being attached to the'backing strip and the latter being provided, intermediate the ends of the film strip and zadjacent the outer attached end of tlf-e filrr strip, with a relatively easily lm'gitudiiially expansible section.

JOHN A. ROBERTSON.

"Witnessesfz w s GRACE MENLENDYKE, RUSSELL B. Gmrrrrrn

Images