Patent GB-694933-A (GB)
Title: Kinematograph film registering apparatus
Inventor: ANDREAS JOHN MOORE
IPC: G03B27/08
Filed: 1951-12-03
Abstract: 694,933. Kinematograph film registering apparatus. TECHNICOLOR MOTION PIC. TURE CORPORATION. Dec. 3, 1951, No. 28274/51. Class 98 (ii). To register kinematograph films, two films are fed about a smooth drum in superposition through an arc which is many times as long as the width of the film and are driven by feed-on sprockets engaging the films before they reach the drum and take-off sprockets engaging the films after they leave the drum, the sprockets being rotated in unison to turn at the same tooth speed, and the tension on one of the films is automatically and continuously adjusted so that they travel round the drum at the same perforation speed by a loaded guide pressing transversely on the shorter film as this approaches the drum. The apparatus is applicable to photographic contact and imbibitionprinting and to stripping an emulsion layer from one kinematograph film support and transferring it to another. As shown, a negative film N and an unexposed positive film P, on which the negative is to be printed by lamps 5, are fed by sprockets 16, 6 over tensioning loops 17, 12 to a smooth drum 1 on which they are seated by rollers 19, 8, and are removed from the drum over a roller 9, whereafter they pass separately over tensioning loops 21, 13 to takeoff sprockets 22, 11, the four sprockets being geared together to be rotated in step by a motor M which drives the drum through a variable-speed transmission 4. The movable pulleys in the loops 12, 13 are provided with weights 14, 15 to maintain the positive under tension, while from the pulleys in the loops 17, 21 depends a bar 24 from the middle of which is suspended by a spring 25 a heavy piston 26 movable in a cylinder 27 supplied with compressed air through a port 29 regulable by a valve 28 suspended from the bar beneath the loop 17. The negative film seating roller 19 and the take-off roller 9 may be forced against the drum by springs S to prevent slippage between the films. If the pitch of the feed perforations of the negative film is less than that of the positive film, so that loop 17 decreases and loop 21 increases, the bar 24 falls on the left and rises on the right, whereupon the flow of air into the cylinder 27 decreases and the piston falls, thereby increasing the tension in both the loops 17, 21 until the negative film is stretched sufficiently to have the same perforation pitch as the positive when the two films travel in step. If the pitch of the negative is greater than that of the positive, the action is reversed. In a modification in which the drum is freely rotatable and driven by the films, the positive film loop on the take-off side of the drum may be omitted and the pulleys in the negative loops are not connected, the feed-on loop pulley being attached to the free end of a fixed adjustable spring. The tension in the feed-on loop for the negative film may be reduced by providing two feed-on sprockets in tandem with a weighted loop between them, and the stretching of the negative film may be increased by braking the film seating roller. The drum may be provided with a groove adjacent one margin so that when printing a sound track the surface of the film is not scratched, and either the seating and guiding rollers may be flanged or guiding rollers having axes perpendicular to the film may be employed. If desired the smooth drum may be stationary and the films may be supported thereon by anti-friction means as described in U.S.A. Specification 2,561,497. The films may be seated helically around the drum for more than one complete turn. When making photographic contact prints, the duration of the exposure may be changed either by altering the speed of the machine or by cutting off part of the light with a shutter.