GB606000A - Improvements in and relating to continuous feed kinematograph apparatus - Google Patents

Abstract

606,000. Kinematograph apparatus. MAYTUM, J. A., and SMITH, L. Feb. 15, 1946, No. 4864. [Class 97 (i)] In continuous feed apparatus a toothed wheel driven only by engagement with the film is coaxial with, but laterally offset from, an optically compensating prism driven thereby and a fixed prism deviates the light path to include the film and the compensating prism. In the projector shown, the film 31 is driven by a friction roller 21 with a rubber surface and a pressure roller 22 and is wound on to a take-up spool with slipping belt drive 27. The roller 21 is driven by the motor 23. The film is drawn round the sprocket 20, carrying the optical compensator, and over a film guide 14 past the projection aperture 15 from the spool 25. The sprocket 20 is thus in line with the aperture 15 and the rhombic prism 16 produces the sideways displacement of the light beam so that it passes through the compensator 17 and projection lens 18. The compensator may be a square prism as in Specification 597,090, or a polygonal ring of plates. In the latter case, one end of the rhombic prism is within the ring of plates. A shutter, pivoted round the axis of the sprocket 20, has a spring urged tooth engaging a film perforation and carrying it across the aperture 15 at the time of changeover between succeeding facets of the compensator. The tooth then strikes a dimple on the guide 14 and the shutter is released to fly back under spring action to engage the next film frame. This movement is damped frictionally or magnetically or by a pawl on the shutter arm engaging a toothed wheel on the sprocket shaft. An adjustable roller may be provided in contact with the film where it passes over a recess in the film guide by which the length of the film path may be varied for framing.