GB807779A - Improvements in or relating to transparency changers for optical projecting devices - Google Patents

Abstract

807,779. Optical projection apparatus LEITZ, G.m.b.H., E. Nov. 27, 1956 [Nov. 28, 1955], No. 36225/56. Class 97(1) In optical projection apparatus, transparencies are arranged in a tray and are movable one at a time from the tray and back again thereinto by means of a slider actuated by a manually operable plunger, the tray being movable stepwise on successive operations of the slider a distance equal to that between adjacent transparencies and the plunger for operating the slider being movable in a direction perpendicular to the direction of motion of the transparencies caused by the slider. A transparency charger, Fig. 2, an optical projector as in Specification 810,692, has a manually operable plunger 16 with a rack 17 engaging a pinion 18 on the same spindle as a pinion 20 meshing with a rack 12 carrying a member 21 with downwardly extending portions 13 and 14 for engaging the vertical edges of the transparencies. The plunger 16 is lifted to move the slider and the transparency to the projecting position and depressed to move them back again. The rack 17 disengages the wheel 18 as the transparency is returned to the tray and the slider is then locked by a projection 16a on the plunger sliding into a slot 16b of the rack 12. When the plunger is further depressed, a spring 24 at its lower end engages and rotates a toothed wheel 25 engaging a rack on the transparency tray which is moved to. bring the next transparency between the arms 13 and 14. In a modification, Fig. 5, the wheel 25 is locked against rotation by the lever 35, and the rack 27 which is vertically displaceable relative to the plunger 28 permanently engages the wheel 18. On depressing the plunger, a ledge 31 of the rack first engages the arm 32 of the lever 35 to rotate the same and unlock the wheel 25 which is thereupon engaged by the lower end of the plunger as in the former embodiment.