Patent GB-554272-A (GB)
Title: Improvements in or relating to cinematograph apparatus
IPC: G03B15/08
Filed: 1941-10-24
Abstract: 554,272. Kinematograph apparatus. REDLER, A. Oct. 24, 1941, Nos. 13715/41 and 13805/42. [Class 97 (i)] In apparatus having means for varying the frequency of film shift while the speed of the drive, and the speed of each film shift, remains constant, e.g. as described in Specification 518,978, a member is driven at constant speed irrespective of film shift frequency and the film shift device is automatically coupled temporarily to it at intervals corresponding to the filmshift frequency; constructions embodying claw, maltese cross, and heater feeds are described, and also means for controlling frequency change by a notched film, for effecting reverse feeding and controlling film tension during such feeding, for driving the shutter at constant speed, and for reducing shock when the frequency is changed. As shown, a shaft 1 driven by a motor M at a constant speed of 32 revolutions per second carries gears 1a, 1b, 1c permanently meshed with gears 2a, 2b on a shaft 2, and, through reduction gears 2d, with a gear 2c thereon. The gears 2a, 2b, 2c are alternatively operative to drive the shaft 2, and the gear ratios are such that they respectively make 16, 8 and 1 revolutions per second. Cranks A<SP>2</SP>, A<SP>1</SP>, on the shafts 2, 1, respectively carry a claw arm A3 and a link A4 connected thereto. The crank A<SP>1</SP> has a constant speed of 32 revs. per second, but the crank A<SP>2</SP> is rotated during periods of film dwell at the speed of one of the gears 2a, 2b, 2c, and during all periods of film shift at the speed of the gear 2a Control of the speed of the crank A<SP>2</SP> is effected by a pawl 4a on the gear 2a, a ratchet wheel 4 keyed to the shaft 2, and a fixed cam disc 9 secured to the casing C2. The cam disc 9 has a depression 9a, Fig. 4, extending over a quarter of its circumference, and the pawl 4a carries a pin 4b pressed by a spring 4e carried by the gear 2a so as to ride on the cam disc. The timing is such that, if the gear 2a drives the shaft 2, the pin 4b enters the depression 9a at the point P<SP>1</SP> just as a notch in the wheel 4 is in position to receive the pawl. If the shaft 2 is driven more slowly by one of the gears 2b, 2c, the pawl, on reaching the point P<SP>1</SP>, rides over the edge of the wheel 4 if the notch therein is not also at P<SP>1</SP>. The cam keeps the pawl from engagement with the notch in the wheel 4 until the wheel has made sufficient revolutions to bring the notch to the point P<SP>1</SP> at the same time as the pawl ; the engagement then causes the shaft 2 to be driven by the wheel 2a until the point P<SP>2</SP> at the end of the depression is reached, and film feed occurs during this time. The gear 2c drives the shaft 2 by a pawl 6a engaging a ratchet 6 keyed to the shaft, and toothed throughout its circumference; when the shaft is driven more quickly by another gear the pawl rides over the teeth. A sliding clutch member 3, keyed to the shaft 2, may be in neutral position, or may alternatively connect the gears 2a, 2b to the shaft, the former by direct engagement, and the latter by engagement with a ratchet wheel 5 free on the shaft 2 and driven by a pawl 5a carried by the gear 2b. The member 3 is moved by a fork R<SP>1</SP> pivoted on a rod R and operated by a spring 15 secured to the rod. The rod may be turned manually to any of three positions, corresponding to clutch positions, by a handle L<SP>1</SP> or may be turned to two other positions, respectively corresponding to the engaged positions of the clutch, permitting change from fast running to slow running (through the gear 2c) to be made under the control of notches in the film edge and of a lever 12 carrying a spring plunger 13 engaging the film edge. The pawls, ratchet, notches &c. may be duplicated, as shown, to render possible the reverse drive of the film when the motor M is reversed. A handle L<SP>2</SP> on a rod 17 carrying a switch arm 18 may occupy any of three positions for forward drive (as shown in Fig. 1), for rest, or for reverse drive. When the handle is moved over for reverse drive, an arm 19 on the rod 17 raises a slide carrying a roller 20a which comes into engagement with, and takes up, the upper film loop. The upper and lower film spools may be driven by chains 33, 34 from a chain wheel 30a on the shaft 2, and a shutter 29 may be constantly rotated at revolutions per second by a chain engaging a chain wheel 261 on the shaft 1. Shock-absorbing spring connections between gears, chain wheels &c. and the keys connecting them to their shafts are described. The cams operating the claw arm may be replaced by a single cam turning within a rectangular frame in a claw-arm rocking about a fixed point, modifications being made in the mechanism accordingly. Constructions of the mechanism associated respectively with the pin wheel of a maltese cross mechanism, and with one of two cranks operating a film heater are also described. According to the first Provisional Specification, the cam disc 9 is rotatable and variably controlled by a sliding stop-bar in two parts, in accordance with the frequency of film shift.