Patent GB-150298-A (GB)
Title: Improvements relating to kinematograph apparatus
IPC: G03B21/43
Filed: 1920-05-07
Abstract: 150,298. Petra Akt.-Ges. f³r Elektromechanik. Aug. 26, 1919, [Convention date]. Kinematograph apparatus.-Relates to kinematograph projection apparatus having means for automatically rewinding the film on to the feedspool, after an exhibition, without reversing the motor. The apparatus is so constructed that during rewinding the pressure plate at the gate is removed, the film is freed from the feed-sprockets, and the lamp circuit is broken; means for maintaining the film loops may also be provided. Figs. 1 and 2 show opposite elevations of an apparatus in accordance with the invention having its parts in the projecting position, and projecting vertically. The film passes from a feed-spool 2 over a sprocket 3 to the gate 4, and thence over a sprocket 5 to the take-up spool 6. A driving- shaft 10 is geared by wheels 11, 12 to a shaft 13 having bevel wheels 14, 23 geared with bevel wheels 15, 24 on the shafts 16, 25 of the sprockets. The shaft 16 carries a pulley geared with a pulley on the spindle 18 of the spool 6 by an elastic cord 17. A tensioning-roller 19 on a lever 20 having an arm 21 bearing on an arm 22 projecting from the lamp house 7 keeps the cord 17 tight during projection. During rewinding, the lamp house 7 is lowered. It then allows the cord 17 to become slack, and also, by the engagement of a lug 72 with a lever 73, raises a rod 74, and brings clutch-elements 28, 29 into engagement, so that the spool 2 is driven by shafts 27, 30 from the bevel-wheel 24. The lamp house carries a pressure plate 9 and arms 69 carrying pressure rollers 68, the arms removing the film from the sprockets 3, 5 as the lamp house is lowered. A rod 77 fixed to the lamp house tilts a mercury switch 79 as the lamp house is lowered and breaks the lamp circuit. The up and down movements of the lamp house are controlled by a sliding rod 53 which is normally held by pawls 54, 55. During projection, an arm 45 bearing on the film on the spool 2 turns about its pivot 50 by spring action and turns an arm 49 against a spring 52 on .the rod 53. When the film is unwound from the spool 2, the arm 49 engages a lug 60 on the pawl 54 and lifts the pawl so that the spring 52 can slide the rod 53. A pin 61 on the rod 53 then slides a clutch element 62 on the shaft so that a screwed spindle 65 is rotated, and a nut 66 thereon, secured to the lamp house, travels downwards. When the lamp house reaches its lowest position, an inclined surface 70 attached thereto engages a coned flange 71 on the clutch element and disengages the clutch. Arms 45, 46, a spring 58, pin 81, and clutch element 82, function in connexion with the spool 6 during reminding in the same way as the corresponding parts described in connexion with the spool 2 function during exhibition, the lamp house being raised at the end of the rewinding operation and bringing a curved member 84 into contact with the clutch element 82 to disengage it and stop the upward movement. Maintenance of the film loops is effected by mounting the sprockets 3, 5 loosely on their spindles and driving them by pawls 3&, 37 from ratchets 34, 35 fast on the spindles. If the film becomes tight between the sprocket 3 and the gate, the pawl 38 overruns the ratchet 34 and causes a loop to be again formed. If the film becomes tight between the gate and the sprocket 5, a spring raised arm 39, pivoted on the lamp house and carrying a roller 40 over which the film passes, becomes depressed by the film. The free end 42 of the arm 39 then comes into the path of pins 43 on the sprocket 5 so as to hold the sprocket while film accumulates between it and the gate, the arm being then again raised by the spring and freeing the sprocket.