GB990683A - Magazine-type transparency slide projector - Google Patents

Abstract

990,683. Magazine-type slide projectors. FRANKE & HEIDECKE G.m.b.H., [trading as ROLLEIWERKE FRANKE & HEIDECKE]. Dec. 19,1961 [Dec. 22,1960], No. 45428/61. Addition to 965,558. Heading G2J. In an improvement in or modification of the magazine-type slide projector disclosed in the parent Specification in which two magazines movable in parallel guideways on opposite sides of the projector are provided for slides of different formats,a pair of pivoted masks located in the path of the projection light beam are arranged to be opened only when a slide is located in one or other of the two alternative projection positions. In the projector of the parent, two slide changing claws 17,18 are provided for slides of two different sizes, these claws being respectively slidable transversely of the optical axis on rods 19, 20 and being driven in feed and return movements by driving means (not shown) through links 28, 29, a double armed lever 27, a pinion 26, a reciprocating rack 24 and a cam 22 on a driving shaft 21. A knob 23 is provided for manual control. A pair of masks 34, 35 are now provided pivoted respectively about vertical axes 32, 33 and linked by a member 35c. The masks are urged towards their open positions by a spring 38 acting on a lever 36 fixed relative to mark 34 but are normally held closed by a pin 39 on the lever 36 engaging in a cam groove 40 rigid with a pinion 41 meshing with a further pinion 30 on the driving shaft 21. The pinion 41 rotates twice for each rotation of the pinion 30. A radially enlarged portion 42 of the groove 40 is arranged so that when the claws 17 and 18 are in their projection positions (and also in their outermost positions) the pin 39 is released for opening of the masks 34, 35. Opening of the masks, however, is prevented unless a slide is correctly positioned in one or other of the two gates by a latching device comprising sliding members 49, 50 having lugs 62,63 engageable by properly positioned slides and a spring-urged lever 45 which is coupled to the members 49, 50 by arms 47,48 and has a lug 43 normally positioned in the path of movement of the lever 36. The slides may be provided with three rounded or recessed corners and only one square one so that the lugs 62,63 can only be engaged by properly oriented slides. The masks 34,35 may be provided with notches thereby forming a central hole 72 when closed so as to reduce eyestrain caused by continual changes from light to dark on the screen. The hole 72 may also serve as a pin-hole objective for producing an image of the lamp filament on the screen for facilitating positioning of the sources. The projection lens would be removed for this. Alternatively the projection lens may be retained and the positioning effected with reference to an image produced on a frosted glass screen held in front of the projection lens (cf. Fig. 4 not shown).