GB442706A - Improvements in or relating to continuous feed mechanism for sound picture films - Google Patents

Abstract

442,706. Gearing for conveying rotary motion. TOMLINS, F. C., Melbourne House, Aldwych, London.-(Electrical Research Products, Inc. ; 195, Broadway, New York, U.S.A.) May 3, 1935, No. 13209. [Class 80 (i)] [See also Group XXXVIII] In combined sound- and - picture film apparatus, for obtaining uniform velocity of a filmfeeding sprocket wheel, the sprocket is driven by a multiple arrangement comprising motordriven gears connected through an elastic coupling to the sprocket and a pulley which is rigidly connected to the sprocket and to which a separate drive is transmitted by a belt. A single motor 20 is employed in the construction shown, the motor driving shafts 25, 26 through wheels 22, 23 and through reduction gearing in a gear-box 24, the shaft 26 being provided for feeding the film 2 through the picture head (not shown). On a shaft 4 is a sprocket 1 for feeding the film past the sound gate 3. A pulley 5 is fixed on the shaft 4, and is connected through light springs 15 and a spider 13 to a sleeve 9, to which is secured a wheel 7 gearing with a wheel 8 on the shaft 25. A belt 18 passes over the pulley 5 and over a pulley 19 on the motor shaft 21. When the machine is driven at normal speed, the belt creep causes some stressing of the springs 15, whereby the teeth of the gear 7 are pressed against those of 8 in the non- driving direction. The sprocket shaft 4 is thus driven uniformly by the belt, but only at a rate permitted by the gears 7, 8. Momentary variations in the velocity of the gears are absorbed by the springs. In a modification, (Figs. 3 and 4, not shown), instead of using a common motor, the pulley is driven by a small separate motor which has a slightly greater driving torque than that required by the normal load of the film. During the driving of the film, the springs are stretched a given amount, and thus absorb the excess torque of the motor and regulate its speed. The belt-driving motor may be a 1 /100 H.P. three-phase induction motor, and is secured to a base which is adjustably mounted on a shaft, whereby the required tension of the belt may be obtained. The speed-regulating apparatus described in Specifications 275,582 and 297,135, [both in Class 38 (iii)], may be used in carrying out the invention.