GB1458819A - Film cassettes - Google Patents

Abstract

1458819 Light-tight film cassette CIBAGEIGY AG 18 April 1974 [16 May 1973] 23347/73 Heading B8M A cylindrical cassette for a spool of photographic film has an exit slot formed by a pair of lips 2, 9 between which the leading edge of the film may protrude, lip 2 being an extension of the peripheral wall and lip 9 being an extension of curved member 20 which forms with the peripheral wall a light labyrinth through which the film travels from the reel to the exit slot, the surface of lip 2 which helps define the slot constituting a tangent to a circle concentric with the longitudinal axis of the cylinder, the circle having a diameter of less than 0À8 of the internal diameter of the cylindrical cassette and preferably at least 0À6 times. Preferably the cassette comprises two halves 1, 8 each having two lugs 10, 11 and 3, 4 which co-operate to lock the cassette together. Lugs 4, 11 are rounded to facilitate snapping lugs 3, 10 together. The end walls have overlapping portions and/or tongues and grooves to keep out light. The cassette halves are moulded from polystyrene, polypropylene, acrylonitrile-butadienestyrene copolymer, cellulose nitrate or cellulose acetate. The material contains 5% polytetrafluoroethylene to reduce friction and carbon black or titanium oxide plus dye to render it opaque. The surface of the light labyrinth over which the picture area of the film travels is matt and is recessed compared to the rest of the labyrinth surface. Specification 1,458,820 shows the same cassette. Its claims are directed particularly to the means for securing together and light proofing the cassette.