GB677425A - Improvements in sound film recording or reproducing devices - Google Patents

Abstract

677,425. Optical sound recording and reproducing apparatus. PESTEL, J. Jan. 17, 1949. [Jan. 19, 1948 ; Oct. 12, 1948] Nos. 1313/49 and 1314/49. Class 40 (ii). Relates to sound film recording apparatus and provides for a uniform speed of movement of the film in front of the photoelectric cell by enabling perfect adhesion of the film to the fly-wheel driven drum by the pull of the film and having a surface engaged by one edge of the film, said drum including a friction device acting against the other edge of the film, in the form of a lateral inherently resilient check concentric with the fly-wheel drum and projecting beyond the periphery of the latter, the said resilient check serving to press the film by the edge against the said surface of the drum so that the latter steadies the film movement and damps vibrating which may be produced in its running. The drum has elements 13, 14 forming checks to bear against the edges of the film. The element 14 is a thin metal disc with holes to increase its flexibility, and it is backed by a steel disc 15 cut so as to provide a series of blade springs, as in Fig. 4. The element 13 is hollow and houses a photo-electric cell which is held inside it by an arm passing through a gap 21 between it and the drum 12. On the shaft 8 of the drum is a flywheel 9. The shaft 8 runs in bearings 3 and 5, the latter being in a cage 4 which may be moved lengthwise of the shaft. A spring 10 is provided to take up play in the bearings. The assembly is mounted in a casing 1. The film is fed on the drum from a roller 17 which has a flange 20, disposed as shown so that, at the point where the film meets the drum, the discs 14, 15 are bent back to allow the film to pass. The drum is slightly narrower than the film, so when the latter is wound on the drum it is firmly clamped between the cheeks 13, 14. The drum assembly may be adjusted laterally by a screw 25 acting on the end of a lever 26 pivoted at 27, the other end of the lever being forked and acting on the cage 4, contact being maintained by the spring 10. To hold the drum in its adjusted position the casing 1 is split lengthwise and has lugs 28 through which is passed a threaded rod 29, Fig. 8, passing also through a tube 37. The rod 29 has a transverse opening through which passes an eccentric portion of a key 36 which is held in two holes in the tube 37. When the key 36 is turned by its cross piece 39 its eccentric portion engages the side of the hole in the rod 29 and causes the lugs 28 to converge, so clamping the cage 4. The necessity for the gap 21 may be avoided by making the drum of transparent material, in which case it may incorporate a prismatic formation to direct rays from a.light source to the photo-electric cell. Instead of using a flexible disc to clamp the film the check may have a rubber or similar inset, or a, series of balls arranged to run on the film, and the flexible disc may be displaced where the film meets the drum by a roller whose axis is perpendicular to that of the drum.