GB705026A - Improvements in or relating to an optical projection apparatus - Google Patents

Abstract

705,026. Optical projection apparatus. WATERWORTH, E. N. Sept. 17, 1951 [Sept. 18, 1950], No. 21754/51. Class 97(1) An episcopic projector comprises a carriage for a plane original, a plane surface on which the carriage is movable in two directions perpendicular to each other and to the axis of a lens which projects an image on to a screen, and illuminating means comprising a light source and condenser and a lens and prism to concentrate the light beam on to the original. As shown, the original is clamped between a glass plate 5 and a resiliently mounted plate 6, both mounted on a carriage 15 on a baseplate 16. Brackets 17 on the carriage embrace a rod 18 and impose lateral, but not vertical constraint. The rod 18 is secured to a rod 19 slidable in fixed brackets 20 by rack and pinion 23, 22 actuated by a knob 21 to produce longitudinal movement of the carriage 15. Transverse movement along the rod 18 is produced through a rack 29 engaged by a pinion on a shaft 27 squared or splined to be slidable in a bevel pinion 26 meshing with a pinion 25 rotatable by a knob 24. The baseplate 16 is grooved to prevent accumulation of dirt in the way of the carriage 15. The illumination system shown in Fig. 3 includes a condenser 7 and a tapered prism 9, to which are secured lenses 8, 10 to concentrate light on the portion of the original below the objective 12. The projection beam is reflected by a mirror 14 to form an image on the screen 13. The lower part of the apparatus is enclosed by a casing, part of which is shown at 36.