Patent GB-553046-A (GB)
Title: Improvements in or relating to photographic cameras
IPC: G03B27/46
Filed: 1942-03-20
Abstract: 553,046. Photographic cameras. POWERS, F. T. March 20, 1942, No. 3740. [Class 98 (i)] A camera comprises means for feeding a length of the sensitive material to the image field, a support for the length of material to be exposed, suction means for holding the material on the support, and cutting means between the support and feeding means for severing the length from the remainder of the material. In the copying- camera shown, a body 1 set in the wall 8 of a dark room, from which the interior is accessible through doors 9, 10, contains two rolls of film 12, 13 of different widths, the ends of which pass respectively between feed rollers 14. 15 and pressure rollers 30, 31. The rollers 14, 15 are rotated bv external handles and operate through gears indicators showing the length of film fed. The film is fed in front of a platen 70, Fig. 5, and behind two vertical strip-form guides 49, 50. Figs. 3, 6, which are secured at their ends respectively to the upper and lower runs of sprocket chains 48, 51. The sprockets at one end of these chains are connected through bevel gears and a sprocket chain 62 for simultaneous rotation by a handle 45, thus allowing' the guides 49, 50 to be simultaneously and equally adjusted towards and from each other so as to overlie the edges of the film in use. The platen 70 is held between channelled side members 79, 80 secured together by shafts 85, 86. Rollers 86a, b on the ends of the shaft 86 engage in channel members 86c, d so that, by means of link mechanism 108, 109, 110, 111, 112 operated by rocking a shaft 105 carrying the links 108, the platen may be withdrawn from the position of use shown in Fig. 1 to a slightly forwardly-inclined position nearer the back of camera. After the required length of film has been fed behind the guides 49, 50 the platen is moved forward to the operative position shown in Fig. 1, when a mercury switch carried by one of the links 108 completes the circuit of a motor driving an exhauster which is connected by a hose 78 to cavities in the platen communicating with clusters of apertures 74 in the front plate 71, which is preferably of resilient material. The film to be exposed, which is thus held to the platen by suction, is then severed from the roll by traversing across it a circular cutter 38 which co-operates with a fixed blade 37 and is mounted on a carriage slidable on a bar 40 by means of an external handle. At the end of its traverse the carriage engages a lever which raises a rod 118 carrying cam collars 121, 122 adapted to engage arms 123, 124 frictionally secured to the shafts 16, 17 of the feeding rollers, so rocking the shafts and turning the feed rolls slightly backwards. The cut edges of the films are thus retracted, that of the film not in use remaining so until the film is again fed down, thus avoiding fraying of the edge by repeated passages of the cutter along it during use of the other film. After the length of film to be exposed has been thus severed, the platen 70 carrying it is adjusted vertically in the channel members 79, 80 by rotation of a shaft 87 carrying sprockets on which are sprocket chains 90, 91 secured to the platen. A spring 93 on the shaft 87 counterbalances the platen. The shaft 87 is rotated by a handle 98 through a sprocket chain kept taut by idler sprockets as the platen is moved between its front and rear positions.