An optical projection apparatus with picture changer for the progressive projection of lantern slides

摘要

812,925. Optical-projection apparatus. AGFA, A. G. Oct. 31, 1955, No. 31093/55. Class 97(1) A vertically movable member carries jaws at its lower end for gripping a slide and lifting it, from a magazine below the optical system, into projecting position and subsequently replacing it, each downward movement causing the magazine to move forward one step so that the next slide is lifted on the next stroke. In the form shown a housing 6 contains a plate 7 operated by a knob 8 and having pivoted at 9, jaws 10 urged together by a spring 11 and of V-section at their lower inner edges so as to grip the edges of a slide in the magazine 3. The slide is raised to projecting position at the aperture 6c by lifting the knob 8. As it is subsequently lowered rollers 12 pivoted on the jaws 10 strike cams 13 to open the jaws to release the slide and permit movement of the magazine. This movement is produced by one on the spindle 15 of a pinion 14 enried o nthe spindle 15 of a pinion 14 engaging a rack on the side of the magazine. The knob 16 is urged upwardly by a spring 17 and connected to the spindle 15 by a pin and helical slot so that axial movement of the knob produces relative rotation of knob and spindle. A spring pawl 20 bears on ratchet teeth on the knob and a spring pawl 19 bears on pinion 14. The pawls are arranged so that pinion rotates to move the magazine forward as the knob is depressed, whereas, when the knob is released, it rotates, leaving the pinion stationary. When the magazine is inserted initially its movement is stopped at a position for projecting the first slide, by a spring urged lever 22 in its path. This lever is moved aside by one of the jaws 10 during the first downward stroke of the plate 7 and subsequently bears on the side of the magazine. Since the slides are removed from the top of the magazine no slots are required in the magazine and a detachable cover for the magazine encloses the slides completely. A spring detent 6e locates the plate 7 in the projection position. The plate may be spring biased towards one end of its travel. Downward movement of a plate 7 lowers a shutter 24 over the aperture 6c while the slides are changed.