Patent GB-563544-A (GB)
Title: Improvements relating to apparatus for photographic copying
IPC: G03B27/465
Filed: 1943-03-15
Abstract: 563,544. Photographic copying apparatus. WRAY (OPTICAL WORKS), Ltd., SMITH, A. W., and JOHNSON, B. K. March 15, 1943, No. 4215. [Class 98 (i)] Apparatus for copying documents, books, &c. comprises a table-like open structure, the top of which contains a transparent support for the original illuminated from below, and the legs of which carry a lower support for an upwardlydirected enclosed film camera, the structure carrying also a pedal coupled to the camera so that on operating the pedal the film is advanced and the shutter is actuated. Switch contacts in the circuit of the illuminating lamps may be interconnected with the shutter mechanism of the camera so that the lamps are energized only when an exposure is being made. As shown, a table 1, Fig. 1, has an aperture into which is recessed a glass plate 4 on which the document &c. is pressed face downwards by a weighted platen. Cross-bars 9 between the legs 2 support shaded; angularly-adjustable lamps 8. A shelf 5 near floor-level supports the camera 6 with lens 7 directed towards the plate 4, the camera mechanism being controlled by a spring-biassed pedal 19 operating through linkage 18 a crank 17 fixed on a shaft 16 mounted in the camera body. Shaft 16 operates through ratchet mechanism a feed sprocket 14, Fig. 4, which draws film 29 from a supply spool 8 through the exposure gate 11 and over a guide roller'10, delivering it to a take-up spool 12 which is belt-driven from the sprocket through a slipping clutch at a speed which maintains the film taut ; the ratchet mechanism permits a 90 degrees rotation of the sprocket 14 when the pedal is depressed, the sprocket remaining stationary when the pedal is released. The film is held in the exposure gate 11 by a pressure plate 30 mounted on a pivoted arm 33 retained in operative position by a spring 32 ; a spring clip may also be provided to secure the plate in position. The crank 17 has a foot adapted, when the pedal is depressed and released to rock a stirrup 41, Fig. 1, the arm 42 of which is pivoted at 43, Fig., 3, in the lens shutter casing 35, and is biassed by a spring 47. An extension of this arm is pivoted to a link 44 pivoted at 45 to a sector plate 37, the pivot pin 45 bearing against the edge of an exposure aperture 36 in a shutter slide 34 adapted to move in guides 34a across the lens aperture 46. A bracket 48 on this slide is connected on the one hand to the piston 38 of a dashpot 39 and on the other hand to a tension spring 50. With the arm 42, link 44 and sector 37 in the full-line positions shown, the lens aperture 46 is obscured by the slide 34 only. When the arm 42 is rocked by depressing the pedal, slide 34 moves to the left, stressing spring 50, until its aperture 36 registers with the lens aperture 46, but this is not uncovered because the obscuring sector 37 moves ahead of the aperture 36 in the slide. When the pedal is released, the spring 47 rocks the arm 42 back, so that the link 44 rapidly withdraws the sector 37, initiating the exposure ; owing to the action of the dashpot 38, 39 the slide 34 follows relatively slowly under pull of the spring 50, so that the lens aperture 46 remains uncovered for a period depending on the time taken by the dashpot piston 38 to uncover an air inlet 51, whereafter the spring 50 rapidly withdraws the slide 34 to its original obscuring position. This period may be regulated by pre-setting the dashpot cylinder to different positions by means of a handle 52 moving over a scale 54. Thus, depression of the pedal feeds the film and arms the shutter ; release of the pedal releases the shutter to make the exposure. To synchronise the illumination with the shutter operation, the circuit of the lamps 8 includes contacts 57, Fig. 3, normally maintained open by pressure of a rod 55, mounted on the bracket 48, against a spring 56 carrying one of the contacts. When the shutter slide begins to move to the left, the spring 56 is moved by a biassing spring 58 to close the contacts 57, thus energizing the lamps, which remain lit until the contacts 57 are opened again by the rod 55 on return of the slide 34 after exposure.