Patent GB-617618-A (GB)
Title: Improvements in motion picture film apparatus
IPC: G03D13/00
Filed: 1946-04-23
Abstract: 617,618. Registering kinematograph films. KODAK, Ltd. April 23, 1946, No. 12307. Convention date, April 20, 1945. [Class 98 (ii)] Apparatus for registering two film strips having similar perforations along at least one margin includes two sprockets or two sets of sprockets over which the strips may be carried in contact with each other, guide means for maintaining the film strips in a straight path whilst passing over said sprockets, and a row of teeth on at least one of each of these sets of sprockets adapted substantially to fill such perforations longitudinally but not laterally, means for holding the films in tension between the two sprockets or two sets of sprockets so as to register accurately the strips longitudinally by means of their perforations, and a row of teeth on said first sprocket or at least one of said first set of sprockets which is expansible to fill the perforations laterally so as to register the strips laterally. The invention is described as applied to the registering section of the emulsion stripping and transferring apparatus described in Specification 582,439 with the differences that the two single sprockets for registering and re-registering the two film strips are replaced by two series of sprockets, the second series of sprockets being driven, rendering unnecessary the separate driving sprocket of the prior Specification. As shown, a transfer film support 11 and a multilayer emulsion film 12, pre-conditioned by passage through a humidifying cabinet as described in Specification 582,436, are passed into a water tank 32 and round a fixed roller 15 and a " floating " weighted roller 18 so as to contact registering sprockets 22 to 25 along a straight path, i.e. tangentially, between two pressure rollers 27, 28 above the water level, which squeeze the surplus water out from between the film strips, over further registering sprockets 36 to 39, past a squeegee blower 110 and a further registering sprocket 40 to a sprocket 41 which delivers the registered film to the stage where the bonding of the uppermost emulsion layer of the multilayer film to the transfer support film is completed, after which the two films are stripped apart with transfer of one emulsion layer. Each pair of sprockets 22-23, 24-25, 36-37, 38-39, is arranged within a guide plate 19 (Fig. 5, not shown), co-operating with which is a guide plate 20 movable for threading and secured by pressure members 20a so as to define a narrow channel for the two films to keep them straight. Roller 28 may be swung away from the fixed roller 27 for threading, a spring 33a normally retaining it in engagement therewith. Each of the sprockets 22 to 25, 36 to 40 has one set of fixed teeth 42a, Fig. 7, and one set of expansible teeth 43. Each expansible tooth comprises a fixed part 47 carried by a web integral with that carrying the fixed teeth and pinned to the sprocket driving shaft, and a movable part 50 carried on a disc fixed on a sleeve splined to the shaft for axial movement thereon, the two parts being urged apart to secure lateral registration of the films by a compression spring disposed between them and a fixed bifurcated stop limiting the travel of the disc. A blade is mounted on the frame of the apparatus for clearing dirt &c. out of the space between the fixed and movable sprocket parts. Sprockets 22 to 25, which are rotated solely by the passage of the film strips, are braked by two friction belts wound sinuously in opposite directions about pulleys coaxial with the sprockets, each belt being anchored at one end to the frame of the apparatus and attached at the other to a weight passing over a pulley. Sprocket 36 is positively driven by a chain and chain wheel but sprockets 37 to 40 are driven by means of pulleys on the sprocket shafts over-driven by a belt drive from a smaller pulley on the shaft of sprocket 36, a " floating " weight passing over a pulley keeping the belt suitably tensioned. Thus the film strips are held under tension between sprockets 22 to 25 and 36 to register the strips longitudinally since (i) edges 57, 58, Fig. 7, of the fixed and expansible teeth of sprockets 22 to 25 engage the rear edges 55, 56 of the film perforations; (ii) edges 61, 63 of the teeth of sprockets 36 to 40 engage the front edges 59, 60 of the perforations, the pressure rollers 27, 28 engaging the films at the point of greatest tension; and (iii) sprockets 37 to 40, by attempting to drive the strips faster than sprocket 36, maintain them in longitudinal registration. The registering sprockets, pressure rollers and the squeegee blower 110 are all mounted on a. single plate removable as a unit for overhaul. When using a film of the kind described in Specification 574,137 which has a yellow filter layer between the uppermost (blue) and the second (green) emulsion layers and stripping layers between the emulsion layers, stripping of the uppermost layer only partially removes the stripping layer, and hence, prior to registering the multilayer film with a second transfer support in preparation for stripping the second emulsion layer, the film 12 is made to pass over cleaning rollers 112, which are supplied with water by jets 119, by manually movable rollers 113, 114 so as to remove the remnants of the stripping layer.