Patent GB-655589-A (GB)
Title: Improvements in or relating to slide-changing devices for optical projection apparatus
IPC: G03B23/04
Filed: 1948-09-10
Abstract: 655,589. Optical - projection apparatus. KODAK, Ltd. Sept. 10, 1948, No. 23852. Convention date, Sept. 24, 1947. [Class 97 (i)] A slide-changing device for use with optical projection apparatus comprises a plate formed with an aperture in registry with which a slide is positioned during projection and carrying a supply magazine for the slides, a slide-changing member reciprocally mounted on the plate at the front end of the magazine to engage an edge of the front slide therein for moving said slide out of the magazine and into the projection position, and slide-separating means for preventing the removal of more than one slide at a time from the magazine upon each reciprocation of the slide-changing member, said means comprising a member carried by the plate adjacent the front end of the magazine and extending across and normally partially blocking the exit opening of the latter so as to be displaced by the slide as it is moved to the projection position by the slide-changing member. As shown in Fig. 3, a plate 15 is formed with the projection aperture. To this plate are attached magazines 17, 18 from and to which the slides are fed spring-pressed members 22, 36 act on the slides therein. The slides are fed successively by reciprocating a plate 19 lying behind the plate 15. The plate 19 has an aperture, in which engages the front slide in the magazine 18 whereby the slide is pushed across to the projection aperture. Reverse movement of the plate 19 retracts the slide. The device shown in Fig. 9 ensures that, after projection, the slide is fed to the magazine 18. It is springy and secured to the rear face of the plate 15 with the fingers 29 extending across the mouth of the magazine 17. As a slide is fed from the magazine it straightens the curved ends 30 of the fingers 29, Fig. 11, until the trailing edge of the slide passes the ends of the fingers. When retracted the slide is thus guided on the front faces of the fingers 29. Since this movement involves inclination of the slide to the planes of the plate 19, the edge 38 of the aperture therein is thickened, so as to remain in contact with the slide by a tongue 39, seen in section in Fig. 4, struck slightly upwards therefrom. The aperture, at the side of the magazine, from which the slides emerge is almost completely blocked by a resilient member 53 which is pushed aside by each slide, to an extent depending on the thickness of the slide. The member 53 is one limb of an L-shaped member, the other limb 51 of which is secured to the base portion 49 of a spring member as shown in Fig. 8. This base portion carries ears 57 and terminates in fingers 45 attached at 46 to the plate 15. If the member 53 is deflected far the end portion 55 engages the ears 57, whereby the fingers 45 are also caused to yield. Spring fingers 48 which engage the slide in the projection aperture also form part of the member. The spring-pressed member 36 acting on the slides in the take-up magazine is inclined as shown in Fig. 3 to assist entry of slides into the magazine.