GB784482A - An optical projection apparatus with picture changer for the progressive projection of lantern slides - Google Patents

Abstract

784,482. Optical-projection apparatus. AGFA CAMERA-WERK AKT.-GES. Feb. 28, 1956 [March 1, 1955], No. 6241/56. Class 97(1) In an optical projector with a slide changer the slides are accommodated, upright and parellel, in a container beneath the projector proper, the container being open topped and having an aperture in the base whereby successive slides can be engaged and pushed up into projection position, the container being advanced after the projection of each slide to bring the next into position for projection, the slide engaging member moving in a curved path to reduce the extent of its vertical movement. In the form shown in Fig. 1 the slides are disposed in channels 12a in the side walls of a box 12 and are pushed upwards for projection, into a channel between the face of a partition 8 and guides 16. The forked pusher member 14a is secured to one end of a steel tape 14 which is slightly curved in transverse crosssection to stiffen it except where it is flattened when led round a roller 17, which, and a roller 18, carry an endless band 19 to which the other end of the tape 14 is secured at 20. The curved transverse crosssection of the tape 14 is maintained by a guide 21 of curved cross-section. The band 19 and hence the tape 14, are actuated, to feed the shoes by the mechanism shown in Fig. 2. Clockwise rotation of a handwheel 23 turns a pivot 22 to which is attached a lever 24, the end 24a of which is attached to the band 19, whereby a slide is lifted to the projection position. At the end of this movement the end 24b of the lever 24 strikes the end of a sliding member 28 coupled to lift a flap 27, pivoted at 27a, which covers the projection aperture during slide changing. A portion of the flap when lifted, bears on spring blades 25 to depress them to grip the slide being projected. During the feed movement of the lever 24 it also bears on a roller 34b at the end of a lever 34 pivoted at 35 and coupled at its lower end 33 to a pawl engaging a rack 12e on the bottom of the box 12, whereby the pawl is pulled back, to engage the next tooth of the rack, against the tension of the spring 36. The box meanwhile is held in position by a latch 31, pivoted at 30 and carrying a tooth 31a also engaging the rack 12e. As the handwheel. 23 and lever 24 are returned to their initial positions to return the slide to the box 12, an abutment 24c on the lever 24 strikes the latch 31 to release the box 12 which is then moved forward by the spring 36 to bring the next slide into position for projection. In another embodiment the projection aperture is covered during slide'changing by a sliding plate which is pushed upwardly by the slide itself as it is moved into position. To reduce the height needed for the movement of such plate it may be replaced by a number of strips which move down to cover different parts of the projection aperture but are moved up into superposition.