Patent GB-545701-A (GB)
Title: Cinematographic film printing apparatus
IPC: G03B27/08
Filed: 1940-12-05
Abstract: 545,701. Kinematograph film printing apparatus. TECHNICOLOR MOTION PICTURE CORPORATION. Dec. 5, 1940, No. 17304. Convention date, Sept. 10. Addition to 536,463. [Class 98 (ii)] [Also in Group XVI] The apparatus of the parent Specification or that of Specification 543,113 is modified (1) by causing the belt to be driven solely by the film or films, which themselves are fed to and from the belt over synchronously - driven film drivers, e.g. sprocket wheels, at points spaced from the belt, (2) by providing tensioning rolls in the film loops between the drivers and the belt, (3) by providing means actuated by notches in the edge of the film for operating a signal or means for changing the printing light, and (4) by providing means for signalling or stopping the machine if one of the films break. Fig. 1 shows schematically the lay-out for printing a positive film P from a sound film S at the printing-head SP and then from a picture negative N at the printing head PP. The arrows show the courses of the various films from their supply reels to their take-up reels. The film drivers are sprockets W synchronously driven by gearing 22-28 from a motor 21. The drums LD, RD are similarly constructed except that the shaft of LD is fixed, and that of RD is slidable, as described in the parent Specification. Drum RD is shown in Fig. 2. It has a film seating 30 of vulcanised rubber flanged with metal rings 31, and is carried on a shaft 33 turning in roller bearings in a mount 37 which is slidably mounted on roller bearings 40 against the action of an adjustable spring 44 in order to maintain the belt taut. Along the lower stretch between the drums, the belt B is backed by a plate 52 on the fixed framework, a plate 53 on the drum mount 37, and between them a wedge-shaped plate 54 actuated by a spring 59 so as to maintain the backing continuous at all separations of the drums. A film cleaning pad 60 is mounted below the plate 54. Film seating rolls R are provided where the films engage and leave the belt; each is mounted on an arm 67 pivoted at 69 and actuated by a spring 71 to press the roll on the belt, the pressure being releasable at will by turning an eccentric 73 normally held by a spring detent. Film tensioning rolls 2, 3, 9, 10, 17, 18 are mounted, as shown at 17, Fig. 2, for the negative film N, on an arm 76 pivoted at 77 and having a lug 80 co-operating with a stop 79 to limit its rocking movement, and the film tension is maintained by pressure of a spring-plunger 81 on the arm 76. The pitch of the teeth on the belt B is made slightly greater than the pitch of the film sprocket holes, and the tension imparted by the rolls 2 &c. is adjusted to stretch the film until the sprocket-hole pitch is equal to or slightly greater than that of the belt teeth so that the film engages with and disengages from the belt smoothly. The roll 17 is flanged on one side at 84, Fig. 5, but not at the other, where a roller 85, adapted to drop into pre-arranged notches in the edge of the film, is mounted on a spring- biased arm 86 pivoted at 87 and carrying an electric spring contact 88 which, on the arrival of a film-notch, engages a fixed contact 89 to operate a signal or change the intensity of the printing light. The device for giving warning or stopping the machine if a film breaks comprises a roller bearing upon one of the rolls, e.g. 7, Fig. 1, and mounted on a spring-biased arm which carries an electric contact normallv pressed by the spring against a fixed contact ; if the film breaks, the roller drops slightly onto the roll (7), thereby opening the contacts to actuate the signal or stop the machine.