Film cassette with flanged film spool

Claim 1

A film cassette wherein a flange has a central opening into which a spool core extends to allow rotation of said spool core relative to said flange in film unwinding and film winding directions, and respective engagement means are located on said flange and said spool core for engaging the flange with the spool core responsive to rotation of the spool core relative to the flange in the unwinding direction to then make the flange rotate with the spool core in the unwinding direction to advance a filmstrip off the spool and for disengaging the flange and the spool core responsive to rotation of the spool core relative to the flange in the winding direction to allow the spool core to rotate independently of the flange in the winding direction to wind a filmstrip onto the spool core, and wherein the improvement comprises: said engagement means located on said spool core is defined by a cut-out in the periphery of the spool core within said central opening in said flange; and said engagement means located on said flange is a locking pawl supported on a resilient cantilever of the flange which biases said locking pawl into said central opening to move from the periphery of said spool core into said cut-out to engage with the spool core when the spool core is rotated relative to the flange in the unwinding direction and to allow the locking pawl to move out of the cut-out to disengage the spool core when the spool core is rotated relative to the flange in the winding direction.