Film spool for a filmstrip

Film cassettes normally include a spool on to which a filmstrip is wound. However, the filmstrip is normally fixed to the spool and needs to be severed therefrom prior to processing. Herein is a spool for a film cassette in which a filmstrip can easily be attached to and detached from the spool. The spool comprises a body portion carrying a pair of flange members and having a slot formed therein, the slot having a pair of shoulders and a protrusion. A pair of pin members are also provided in the body portion. A filmstrip is inserted into slot under shoulders and over protrusion until an aperture therein engages with the protrusion to retain the filmstrip. Inwardly applied pressure to the pin members pushes the filmstrip upwardly so that the aperture clears the protrusion to allow the filmstrip to be detached from the spool.

FIELD OF THE INVENTION 
The present invention relates to improvements in and relating to film 
cassettes and is more particularly concerned with means which allow 
repeated attachment/detachment of a filmstrip to/from a spool core 
retained in such cassettes. 
BACKGROUND OF THE INVENTION 
It is well known to rotatably support a filmstrip on a spool within a film 
cassette. In some such arrangements, the end of the filmstrip adjacent the 
spool is not secured thereto and there is a risk that the filmstrip will 
inadvertently become detached from the spool and hence be wholly withdrawn 
from the cassette during its exposure. One such arrangement is described 
in U.S. Pat. No. 4,145,133. 
There are other arrangements which overcome this problem by attaching the 
trailing edge of the filmstrip to the spool. These arrangements prevent 
the filmstrip being fully extracted from the cassette during exposure, but 
necessitate the use of a cutter to detach the filmstrip from the spool 
prior to processing. 
U.S. Pat. No. 5,054,710 discloses a spool for a camera on to which a 
filmstrip is to be wound during exposure. The spool includes a shaft 
having a slit formed therein. A protrusion is located in the slit to 
engage a perforation in the leading edge of the filmstrip, the filmstrip 
being wound on to the spool as it is exposed in the camera. When the 
filmstrip is fully exposed, it is unwound from this spool back into its 
cassette. The leading edge of the filmstrip slips out of the slit as the 
wall of the perforation engaging the protrusion slides down an angled wall 
thereof to release the filmstrip from the spool. 
U.S. Pat. No. 4,334,750 discloses an arrangement for a spool in a film 
cassette which allows the trailing edge of the filmstrip to be released. 
The arrangement comprises a hollow spool having a slot formed in its wall. 
A retaining member is located within the hollow spool and carries a 
protrusion for engaging a perforation in the trailing edge of the 
filmstrip to retain it in the slot. When it is desired to release the 
filmstrip from the spool, the retaining member is pushed inwardly with 
respect to the spool so that the protrusion is forced out of the slot 
thereby releasing the perforation and the trailing edge. Once pushed in, 
the retaining member cannot be withdrawn from the spool. 
PROBLEM TO BE SOLVED BY THE INVENTION 
Although the arrangement described in U.S. Pat. No. 4,334,750 provides a 
means of releasably attaching a filmstrip to a spool in a film cassette, 
once the retaining member is pushed in to release the filmstrip, the spool 
is not re-usable. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a new spool to which 
the trailing edge of a filmstrip can be releasably attached. 
It is a further object of the present invention to provide an improved film 
cassette which incorporates such a spool. 
A further object of the present invention is to provide a spool for a film 
cassette which is reusable. 
In accordance with one aspect of the present invention, there is provided a 
spool for a filmstrip, the spool comprising: 
a body portion; 
a slot formed in the body portion; and 
a protrusion provided in the slot for engagement with an aperture formed in 
the filmstrip for attaching the filmstrip to the spool; 
characterized in that the spool further includes actuating means operable 
to push the filmstrip so that the aperture formed therein is moved out of 
engagement with the protrusion to detach the filmstrip from the spool. 
Advantageously, the actuating means comprises a pair of pin members which 
are arranged one each end of the body portion of the spool, each pin 
member being movable into slot to engage edges of the filmstrip. 
The pin members are located in respective holes formed in the body portion, 
each hole being aligned with at least a portion of the slot. 
In accordance with another aspect of the present invention, there is 
provided a film cassette incorporating a spool as described above. 
In accordance with a further aspect of the present invention, there is 
provided a method of releasably attaching a filmstrip to a film cassette 
spool as described above, the method comprises the steps of: 
a) inserting the filmstrip into the slot formed in the body portion of the 
cassette spool; 
b) engaging aperture of the filmstrip with the protrusion in the slot; and 
c) detaching the filmstrip from the protrusion, 
characterized in that step c) comprises pushing on the side edges of the 
filmstrip using the actuating means to disengage aperture from the 
protrusion thereby releasing the filmstrip from the spool. 
ADVANTAGEOUS EFFECT OF THE INVENTION 
A simple arrangement is provided by which a filmstrip can be easily 
attached to and detached from a spool in a film cassette, thereby allowing 
the film cassette and spool to be re-used. 
Advantageously, there is no requirement to alter the film finishing or 
punching operations in order to utilize the spool of the present invention 
.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention relates to an improved film spool on which the 
trailing edge of a filmstrip can be releasably mounted. 
In FIG. 1, a film spool 10 is shown. The spool 10 comprises a body portion 
12 which carries two flange members 14, 16 spaced apart along the body 
portion a distance to accommodate the width of the filmstrip to be wound 
thereon. A slot 18 is formed in the body portion 12 for retaining the 
trailing end of the filmstrip (not shown). The slot 18 has a central 
protrusion 20 and two shoulder portions 22, 24 formed one on either side 
of the protrusion 20. A pair of pin members 26, 28 are provided at either 
end of the body portion 12 as shown, the pin members 26, 28 being movable 
into and out of the spool in the direction indicated by arrows `A`. 
FIG. 2 illustrates schematically the slot 18 together with the protrusion 
20 and shoulder portions 22, 24 of the body portion 12 and the two pin 
members 26, 28. Two holes 30, 32 are shown which are shaped and sized to 
receive the pin members 26, 28 as they move into and out of the body 
portion 12 of the spool 10 as indicated by arrows `B`. The cooperation 
between the pin members 26, 28 and their associated holes 30, 32 will be 
described in more detail later. 
A portion of a filmstrip 40 is shown having a trailing end 42 with a single 
central aperture 44 formed therein. For attachment to the spool 10, the 
trailing end 42 of the filmstrip 40 is passed into slot 18 under shoulder 
portions 22, 24, in the direction indicated by arrow `C` so that aperture 
44 engages protrusion 20. Protrusion 20 is ramped to allow the trailing 
end 42 to pass over it until the aperture 44 is reached, the aperture 44 
engaging with the protrusion 20 to retain the trailing end 42 of the 
filmstrip 40 in the slot 18 of the spool 10. Engagement of the aperture 44 
with the protrusion 20 is shown more clearly in FIG. 3. 
FIG. 3 shows the slot 18 with the trailing end 42 of the filmstrip engaged 
therewith. Here, pin members 26, 28 have been pushed out of their respect 
holes 30, 32, indicated by arrows `D`, by the trailing end 42 of the 
filmstrip. Aperture 44 is engaged with protrusion 20. 
When it is desired to detach the trailing end 42 from the spool 10, pin 
members 26, 28 are pushed into their respective holes 30, 32. As this is 
done, the trailing end 42 is pushed upwards so that the aperture 44 clears 
the protrusion 20. This is shown in FIG. 4. The filmstrip can then be 
pulled away from the slot 18 in the spool 10. 
Removal of the trailing end 42 from the slot 18 is made easier if the width 
of the trailing end 42 is slightly wider than the slot 18 so that it is 
always slightly bowed as shown in FIG. 3. This makes it easier for the 
portion of the trailing end 42 having the aperture 44 formed therein to be 
pushed upwards to clear the protrusion 20 and allow the filmstrip 40 to be 
detached from the spool 10. 
TS LIST 
10 . . . film spool 
12 . . . body portion 
14, 16 . . . flange members 
18 . . . slot 
20 . . . central protrusion 
22, 24 . . . shoulder portions 
26, 28 . . . pin members 
30, 32 . . . holes 
40 . . . filmstrip 
42 . . . trailing end 
44 . . . aperture