Improvements in and relating to means for prolonging the exhibition of a single image in cinematographic projection apparatus

摘要

491,042. Kinematograph projectors. OFFICE GENERAL DE LA CINEMATOGRAPHIE FRANCAISE. May 28, 1937, No. 14894. Convention date, March 23. [Class 97 (i)] A delay-action device controlling the operation of means for prolonging the projection of a single image is actuated from the main shaft of the apparatus and is adjustable so that stoppage of the film feed occurs after the projection of a predetermined number of images ; the device may be applied to control the means described in Specification 473,098. A shaft 1 which controls the feed-stopping means, and may correspond to the shaft 19 of the apparatus described in Specification 473,098, carries a stop cam 2 normally held by a rod 3a which is withdrawn when an electromagnet 3 is energized, e.g. by the impact of a bullet on a plate behind a target. The cam 2 is held by a hook 25 when the rod 3a is first withdrawn, and the withdrawal rocks a lever 4 to free a notched disc 5 and also to free a pawl 6, Figs. 2 and 4, which then completes a driving connection between the main shaft of the apparatus and the disc. The pawl is pivoted on a wheel 11 and is also connected to it by a spring 7, the wheel 11 being, loose on a shaft carrying a gear 9 continuously driven by a pinion 10 on the main shaft and secured to a ratchet wheel 8. The pawl, when released, is pulled by the spring 7 into engagement with the ratchet wheel 8, and the wheel 11 and a pinion 12, secured to it, are then driven. The pinion 12 then drives a gear-13 secured to the disc 5 and to a timing shaft 15. The shaft 24 to which the hook 25 is secured carries a pawl engaging the edge of a disc 19 having a notch therein. The disc 19 rotates with the disc 5, and, when the notch comes into position for the pawl to move into it, the hook 25 releases the stop cam 2, and the film feed ceases. The relative positions of the discs 5 and 19 may be adjusted to vary the number of images which are fed before the film feed ceases, the disc 19 being secured to a knob 20 rotatable on the timing shaft 15, and being held by a spring 22 so that a pin 18 projecting from a wheel 17 secured to the shaft 15 engages between selected teeth on a toothed wheel 21 secured to the disc 19. The gearing is such that the wheel 7 rotates once in seven seconds and wheel 21 carries seventy teeth.