Patent GB-201202-A (GB)
Title: A new or improved cinematograph projector
IPC: G03B21/32
Filed: 1922-03-29
Abstract: 201,202. Peranne, J. B. A. E., and Vivant Posters, Ltd. March 29, 1922. No Patent granted (Sealing fee not paid). Kinematograph apparatus. - In projectors comprising two or more pairs of spools and filmfeed mechanisms and also means whereby one film is automatically rewound while another is being exhibited, the feed mechanisms being movable with respect to the optical system so that the rewinding takes place unobstrusively, means are provided for automatically freeing each film in its gate during rewinding, each film passes to and from the gate over opposite sides of one continuous-feed sprocket, the intermittent sprockets are mounted on one shaft and the films pass over opposite sides of them, corresponding film spools are mounted on the same shaft and have driving connection therewith in opposite directions, and means are provided for extinguishing the projection light during the stoppage of the film feed. As shown in Fig. 1, the apparatus comprises pairs of spools 3, 5, 4, 6 mounted on shafts 7, 8, continuous-feed sprockets 17, 19, gates 24, intermittent sprockets 25, 27, a lamp house 75, projection lens 77, shutter 78, and reflectors 79, 80 directing the image to a projection screen 81. The feed mechanism is driven by a motor 50 through a reversing gear 51, shaft 49, clutch 52, shafts 45, 42, 9, 43, and intermittent gearing 29, and is carried by a platform 30 which is moved vertically by mechanism shown in Fig. 3. The sprockets 17, 19 are respectively secured to sleeves 20, 21, Fig. 4, which are rotated in opposite directions by the shaft 42 through spiral gearing 40, 41, and bevel pinions 21<A>, 9<A>, 20<A>. Each spool shaft is driven by pinions 9A, 12, 11, and has clutches 14 whereby one or other of the spools is driven in accordance with the direction of rotation of the spool shaft. Each spool contains a spring 14<B> which presses a washer 14A into engagement with the clutch element carried by it and provides a friction drive. The platform 30, having bearings for the various shafts, is carried by sleeves 32 having helical cam-surfaces 33 and sliding on pillars 31. The surfaces 33 are engaged by helical surfaces 34 on members rotatable by a shaft 38 which is itself driven in one direction or the other by the motor 50, through shafts 49, 38<B>, so as to raise or lower the platform 30. The shaft 49 also drives a shaft 58 which carries a cam 57 operating through a lever 56, Fig. 1, to release the clutch 52 at the end of a film run, and the shaft 58 drives a cam shaft 60 which when the clutch 52 is released causes one of two unidirectional clutch elements 69<C>, 69<D> on the shaft 38<B> to engage a corresponding clutch element on a sleeve 72 constantly driven by the shaft 49, the consequent rotation of the shaft 38<B> resulting in the raising or lowering of the platform 30. Linkwork, preferably operated by the cam on the shaft 60, actuates the reversing gear 51 when the platform has been moved, the films being then fed in the opposite direction. The cam 57 may also operate a switch in the projection lamp circuit so as to extinguish the light when the feed mechanism is stopped, or a speed-controlled contact switch may be provided on the shaft 45. The gates comprise a member 82 fixed to the platform 30 and having apertures 83. A movable plate 84, Fig. 8, is secured over each aperture 83 by a sliding catch and is connected by links 86 and a spring 87<A> with a plate 87 which presses the film against the member 82. Each plate 87 is provided with a lug 88, and one or other of the lugs is pressed by one of two sliding members 89 so that the corresponding plate 87 is held away from the film. The members 89 are moved by an arm 90 frictionally mounted on the shaft 43 so that its position varies with the direction of rotation of the shaft 43. In a modification, fixed guides may cause the gate containing the film being exhibited to be closed, the other being opened by resilient means. The intermittent sprockets 25, 27 may be secured to their shaft 28 by grub screws so that they may be adjusted for film centring.