Patent GB-749884-A (GB)
Title: Improvements in or relating to drive mechanisms
IPC: G03B1/38
Filed: 1953-12-07
Abstract: 749,884. Intermittent toothed gearing. SOC D'EXPLOITATION DES PROCEDES SERIX. Dec. 7, 1953 [Dec. 6 1952], No. 33932/53. Class 80(1) [Also in Group XXVI] In a driving mechanism particularly suitable for moving films comprising a driving member, a driven member and mechanical connecting means therebetween, energy storing means are provided between the driving member and the driven one. In the embodiment described the power from an electric motor drives a Geneva mechanism which intermittently rotates a film driving drum surplus energy from the motor being supplied to a spring during the stationary period of the Geneva mechanism this stored energy being released by the spring to the drum during the rotative period of the mechanism. The electric motor 14 drives at a constant speed a shaft 1 upon which is mounted a plate member 20 integral with a suitably notched (28a) stop plate 28 for the Geneva mechanism. Also mounted upon the shaft 1 and carried by the plate 20 is an arm 21 and a cam 22 the arm and the plate 20 carrying therebetween a roller 23. The shaft 2, which comprises the driven member, has keyed thereto a film drum 3 and a Geneva wheel 25 and carries a triangularly shaped plate 33 which is freely rotatable thereabout. Pivotally connected at one apex of plate 33 is a spring 38 which at its other end is adjustably secured to the mechanism casing. At another apex a 'T-shaped member 30 is pivotally connected at 36 whilst at 34 the member 30 is pivotally connected to an arm 32 which at 35 is pivotally mounted on a plate fixed to the casing. The member 30 carries at 31 a roller 29 for engagement with the cam 22. One edge of plate 33 is formed with a cam surface u, v of radius equal to the radius of movement of roller 23 about shaft 1, a cam surface v, w in radial alignment with shaft 2, and a cam surface 45 which may be of any shape. Fig. 1 shows the roller 23 just emerging from a Geneva wheel slot 24. For the next 270 degrees of revolution of shaft 1 the wheel 25 is stationary but due to the interengagement of cam 22 and roller 29 the member 30 is pushed upwards to rotate the plate 33 in an anti-clockwise direction thus stretching the spring 38. Fig. 5 shows the roller 23 just about to engage a slot 24. The roller 29 is just about to be freed from the cam 22 but it cannot move downwards and the plate 33 cannot move clockwise to release the energy stored in the spring 28 because of the interengagement of roller 23 with the cam surface u, v. For a brief while the wheel 25 rotates but the stored energy is not released. Release occurs when the roller 23 in the slot 24 engages the surface v, w of plate 33. At this position the spring is suddenly released and drives the wheel via the interengagement of cam surface v, w with roller 23 which is in the wheel slot 34. After this energy release the energy storing means 38, 33, 30, 32 then returns to its position indicated in Fig 1. In the foregoing example the operational cycle corresponds to one complete rotation of. the driving shaft 1. This is not essential since the operational cycle could be made to correspond to a fraction of a complete rotation of shaft 1. If the driving shaft rotates through 360‹/n (n being greater than unity) in each operational cycle two sets of n mechanical contact members are carried by the shaft.