Photographic film cassette

#The present invention relates to a photographic film cassette and, more particularly, to an improved photographic film cassette in which the rotation of the core of a spool causes a photographic film leader to advance to the outside of the cassette shell.

#A known photographic film cassette includes a photographic filmstrip positioned so that a photographic film leader does not protrude from a cassette shell prior to loading the cassette into a camera. Such a cassette is easily loaded into the camera. Simple film-advancing mechanisms of the camera are used with this type of cassette and include a construction which rotates the core of a spool to unwind the filmstrip, thereby causing the leader to move through a photographic film passageway and protrude from the cassette. In this construction, a roll of the filmstrip wound about the core is prevented from loosening in order to transmit rotation of the core to the leader. A cassette disclosed in U.S. Pat. Nos. 4,834,306 and 4,848,693 has a spool provided with such disks or flanges on both lateral sides of the roll that circumferential lips are formed on the periphery of the flanges to project in the direction along the length of the cassette. Spreaders or guide projections are formed on the inside of the cassette shell in the positions between the film passageway and a photographic film chamber of the cassette shell for deforming the flanges outwardly to widen the interval between the flanges. The spreaders constantly spread the flanges so as to release the outermost turn of the roll from contact with the circumferential lips.

#In order to produce the core and the flanges, using resin is very favorable since it is convenient and inexpensive. Due to deformation of the flanges, it is necessary for ensuring an unfailing advancement of the leader, with only a small torque applied to the core, to construct the flanges and the circumferential lips with a small thickness, e.g., 0.4 mm or below.

#The above objects and advantages of the present invention will become more apparent from the following detailed description when read in connection with the accompanying drawings, in which:

#FIG. 1 is an exploded perspective view illustrating a photographic film cassette according to the present invention;

#FIG. 2 is a vertical section illustrating the cassette illustrated in FIG. 1;

#In FIGS. 1 and 2 illustrating an inventive photographic film cassette, a cassette shell is constituted of two shell halves 3a and 3b molded from resin. The cassette is composed of the cassette shell, a spool 4 and a photographic filmstrip 5 wound on the spool 4 in a roll. The spool 4 is formed by a core 6 and a pair of disks or flanges 7 and 8 loosely fitted thereon. On the outside of the flanges 7 and 8, the core 6 is provided with rings 9 and 10 fitted thereon for preventing light from being incident on the roll of the filmstrip through the gaps between the core 6 and the flanges 7 and 8.

#Between the shell halves 3a and 3b is formed a photographic film passageway 15 for passing the filmstrip therethrough. On the shell half 3b is formed a separating claw 18 between the passageway 15 and a photographic film chamber of the cassette shell, which claw abuts on a leading end of the filmstrip 5 to separate it from the inner roll and to guide it to the outside of the cassette shell through the passageway 15. Plush or light-trapping fabric pieces 19 and 20 are attached to the passageway 15 in order to prevent ambient light from entering the film chamber. Arcuate ridges 21 and 22 are formed on the lateral walls of the film chamber for contact with the outside surface of the flanges 7 and 8. The ridges 21 and 22 press the lower portions of the flanges 7 and 8 so as to press the end faces of the roll.

#Reference is now made to FIGS. 3 and 4 illustrating an enlarged view of the disk or flange 7. Because the flange 8 is the same as the flange 7, only the flange 7 is described. A hole 40 is formed in the flange 7 at its center for inserting the core 6 therein. A circumferential lip 41 is formed on the circumferential edge of the flange 7 in a vertical direction for contact with a lateral side of the outermost turn of the roll so as to prevent the roll from loosening. The peripheral edge of the lip 41 is provided with a circumferential projection 42 including a collar 42a. The cross section of the lip 41 together with the projection 42 is in the shape of a crank as illustrated in FIG. 4. The surface of the lip 41 to be in contact with the filmstrip 5 is rounded off smoothly, so that the friction between the filmstrip 5 and the lip 41 is kept small.