Patent GB-456686-A (GB)
Title: Improvements in or relating to sound film reproducing apparatus
Filed: 1935-08-20
Abstract: 456,686. Optical sound-reproducing apparatus. ESDAILE, E. W., 21, Towers Street, Arncliffe, and HEPWORTH, R. PLATT-, 68, Paddington Street, Paddington, both near Sydney, Australia. Aug. 20, 1935, No. 23396. Convention date, Aug. 23, 1934. [Class 40 (ii)] Relates to a rotating sound gate for use in sound film reproducing apparatus and consists in an arrangement in which an optical system intermediate the film and the light sensitive cell is contained in a transverse orifice through a stud about which a guide member or members supporting the film are rotatable. Figs. 1 and 2 show a construction in which the film 12 passes under a flanged roller 13 and marginal contact rollers 14 which hold it in light contact with rotatable members 19, 20 independently journalled on anti-friction bearings 21, 22 on a stud 17 keyed at 27 to the frame 18. A block 23 serves as a distance piece between the inner races of the bearings 21, 22, the whole being held in position against displacement on the stud 17 by the screw 25 and washer 26. The optical system is fitted in a transverse aperture 28 in the block 23 and stud 17 in axial relation to the light beam projected from the tube 11 on to the light sensitive cell 29. One marginal edge of the film rides on the flanged edge 31 of the member 20 whilst the other marginal edge runs on the flanged edge 32 of member 19. The member 19 may be cut away at 141 to facilitate access to the optical system for cleaning purposes and, if desired, the axis 42 of the light beam may be slightly tilted laterally as shown at 43 in order to minimize risk of light fringing at the edge 44 of the member 20. The rollers 14 are adapted to rotate freely on trunnions 33 on a wrist piece which is free to rock transversely on the outer end of an arm 35, a spring 36 carried by the arm bearing symmetrically on the wrist piece to prevent undue rotation thereof round the axis of the arm 35. The arm is hollow and a spring 41 within it bears endwise on a flat-ended plunger 40 which in turn bears on a flat 39 cut in a pin 37 on which the arm may be rocked. Alternatively, pressure may be applied by a single roller to the medial portion of the film, the roller being held in a forked support swivelled on the axis of the arm 35. Fig. 3 shows a modified construction in which the film 12 is driven by the revolving drum 45 journalled on the fixed stud 49 which also carries the optical block 23 and a pair of stationary members on the faces 50, 51 of which the margins of the film run without surface contact. Small lateral guide fins 52, 53 may be provided for centring the film to the margins of which light pressure may be applied by a pad or jockey pulley. The outer stationary member 55 is held on the stud 49 by a screw 56 and washer 57, the latter being held against rotation on the stud by a key 58 and being fitted with a spring-controlled latch pin 59 which holds the member 55 against rotation while in the operative position. A portion of member 55 and washer 57 is cut away at 60 to facilitate cleaning of one end of the optical system. By withdrawing the pin 59 and turning member 55 through 180‹ cleaning of the outer end of the optical system is facilitated.