GB701850A - Improvements in or relating to photographic film feeding apparatus - Google Patents

Abstract

701,850. Kinematograph apparatus. KODAK, Ltd. Sept. 19, 1951 [Nov. 17, 1950], No. 21950/51. Class 97(1) [Also in Group XL(b)] Advancing means engage spaced portions of a film and feed it into an upper loop and from a lower loop, a film positioning pin fixed relatively to a gate aperture having a surface substantially perpendicular to the direction of film movement for intermittently engaging a film perforation to locate the film at the gate, air under pressure applied to one of said film loops tending to expand it to maintain one edge of said perforation in engagement with said surface of the positioning pin. In the form shown in Fig. 7, the film F is fed continuously by sprockets 27, 29 inter-connected by gearing and motor driven. Loops L, L1 are formed between the sprockets and a gate member 19 round which the film is guided by rollers 66. The film loops pass 'between a wall, not shown, forming part of the apparatus casing, and plates 72, 73 parallel to the wall and connected to it by perpendicular walls 70. The parallel walls have small clearances from the film edges. Air from a blower is admitted to the spaces enclosed by two film loops through ports 82, 83 in the casing wall, by rotary valves 87, 88. The film loop L is acted on continuously by the air except when the sector 87 covers the port 82. The film is thus tensioned upwardly to register the lower eges of film perforations against the edges 63, Fig. 4, of the chamfered ends 65 of pins 60 secured by screws 62 in grooves 61 in the member 19. When the port 82 is covered the port 83 is uncovered by the port 89 in the valve 88. The loop L1 is then tensioned until the loop L is shortened against a shoe 75 and a fresh frame is registered at the gate. An adjustable epicycle drive is provided to control the instantaneous position of the sprocket 27, and the size of the loop L, when the film is fed. In a modification, air pressure is applied continuously to the loop L1 which is thereby tensioned downwards to register the perforations on the upper surface of a pin chamfered oppositely to that shown in Fig. 4. The film is allowed to feed by reciprocating the register pin. There is no air supply to the loop L but a hole is provided in the wall 70 to allow escape of air at a speed to damp movement of the film on to the shoe 75. In a further modification only one air chamber is provided, round the loop L and air is supplied continuously to register the film on pins as illustrated. The film is fed below the gate by claw or Maltese cross mechanism which is normal apart from some lost motion, for example by pin and slot connecting the Maltese cross with its sprocket. This, results in some over-travel of the film to ensure engagement with the register pins. The air pressure then retracts the film slightly to register it exactly.