Self-catching Spool For Tapelike Record Carriers

Abstract

A spool for tapelike record carriers which automatically grips the record carrier strip as it is inserted between the flanges of the spool.

Description

BACKGROUND OF THE INVENTION

The field of the invention is winding and reeling and the invention is particularly concerned with spools with flanges.

A flanged spool of the present invention is useful for winding and reeling tapelike record carriers wherein during rotation the record carrier, for example a narrow motion picture film, is automatically gripped when it is inserted between the flanges of the spool.

Spools of this kind are already known to the prior art in two fundamentally different forms. On the one hand spools are known which carry on their hub a ring that is usually rotatable and which grips into the perforations of the approaching film to catch the latter, and on the other hand spools are known which carry flat bandlike springs on the inner side of the flange between which the approaching film is gripped and held. In contrast to the first-mentioned system, the film of the second system is subjected to a lateral pressure in such a manner that there is no danger of the film being torn at the perforations. The purpose of the present invention is to technically perfect this second system. Such spools in their present form have the disadvantage of being difficult to manufacture. The spools, which are usually made of synthetic plastic, are formed of two similar halves which are joined at their hubs. The production of such a spool requires two injection operations and one adhering operation which necessitates too many manipulations for such a simple product.

Another serious disadvantage of this prior art system is that the spools do not have in their hub rings any slit in the axial direction into which the film could be threaded and in which it could be clamped tight. Such spools are actually suitable for automatically gripping only and can be used only on a projector which is equipped with a corresponding film receiving device. In other projectors where the film must be fastened manually, such a spool cannot be used at all.

SUMMARY OF THE INVENTION

Having in mind the limitations of the prior art, it is an object of the present invention to avoid these limitations by having the two flanges of the spool consist of equal numbers of spaced apart flange sectors, the sectors of each flange being staggered with the intervals between flanges of the other sector, and whose radial lateral borders are slitted outwardly from the hub ring and cut free at the latter to provide spring elements. To ensure proper functioning it is advantageous to provide axial grooves in the periphery of the hub under the ends of the spring elements with the free ends thereof projecting into the grooves. This prevents the initial turns of the film from being pushed under the free ends of the spring elements by the lateral pressure of the elements.

The subdivision of the spool flanges into sectors, which at one side of the spool are opposite the intermediate vacant spaces at the other side, makes it possible to produce the spools by one manufacturing process and permit them to be sold as soon as they are taken from the injection molding machine. The second injection molding step of the prior art and also the adhering step are completely avoided which means a saving of at least half of the cost of the manufacture.

The present invention also eliminates the last-mentioned difficulty of the prior art by forming the axial slit in the hub ring in a simple manner during the formation of the spool.

The fundamental requirement for catching the film between two leaf springs acting laterally from opposite sides upon the film is that these two springs should be opposite each other in the axial direction. It has however been found that the spools still function satisfactorily with the two spring elements slightly offset from each other while still remaining in the same line of movement of the film. That will permit the use of an injection mold of simple construction for the production of the spool by a single molding step. A further lateral displacement of the spring elements relative to each other is also possible, although with plainly less satisfactory carrying effect. When they are displaced laterally more than a certain amount, they no longer catch the film satisfactorily.

BRIEF DESCRIPTION OF THE DRAWING

The present invention may best be explained by reference to the drawing which illustrates embodiments of the concept of the present invention wherein:

FIG. 1 is a perspective view of the spool;

FIG. 2 is an enlarged fragmentary side view of the flange sectors; and

FIG. 3 is a radial section of the spool.

With particular reference to FIG. 1, the spool is shown with a middle hub 9 and a hub ring 7. The hub ring 7 has three flange sectors 1, 2 and 3 on one side and three other flange sectors 4, 5 and 6 on the other side.

The flange sectors 1 to 6 have catching springs 1a, 1b to 6a, 6b respectively associated therewith.

An axial groove 8 extends through the hub ring 7 to the depth of the flange sector 4. Slots 7a are provided in the hub ring 7 at the free ends of the catching springs 1a, 1b to 6a, 6b.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

It can be clearly seen, especially on FIG. 1, that one side of the spool is provided with three flange sectors 1, 2 and 3 whose radial center lines are spaced 120.degree. from one another. On the other side of the spool the three flange sectors 4, 5 and 6 are of the same construction but are positioned opposite the vacant spaces between the sectors of the first side.

Each flange sector is slitted radially along its two outer edges and in those regions is severed from the hub ring 7 in such a manner that each sector is provided with two inwardly bent catching springs, as shown most clearly at sector 1 which is provided with catching springs 1a, 1b.

The hub ring 7 is also provided with slots 7a into which the free ends of the spring elements extend, since these ends were cut free from the hub ring at the bottom of the slot. The ends of the spring elements will therefore extend into the interior of each slot, inside the periphery of the hub ring.

FIG. 2 clearly shows that the outer edges of neighboring sectors are in circumferential alignment with each other. With this arrangement of the sectors, a dependable catching of the film is assured, and it is also possible to produce the spool by a simple injection molding process. The process proceeds with a separation of the mold sections from one another, and in a manner which also permits formation of the axial groove 8 in the hub ring 7 which could not be formed in the spools of the prior art constructions.

FIG. 3 shows a transverse radial section through the hub of the spool and perpendicular to the film. The middle hub 9 is for receiving the end of the projector shaft and it carries radially projecting walls of equal thickness so as to ensure uniform contraction of the material. The flange sectors of 1 to 6, the hub ring 7, and the middle hub 9 have the same wall thickness.

Claims

I claim:

1. A self-catching unitary spool for a record carrier strip comprising a hub ring (7) and two spool flanges on the top and bottom of said hub ring, each flange defining an equal number of sectors (1--3 and 4--6) with each sector being positioned opposite vacant spaces between the flange sectors of the opposite flange, and radial slits in the lateral margins of each sector which are cut free at said hub ring from said slit to the outer edge of said sector to define leaflike spring elements (1a, 1b--6a, 6b) projecting inwardly from said sectors, the outer edges of said spring elements of two flange sectors on opposite sides of the spool being aligned in the same axial direction whereby said spring elements are offset from each other.