GB853168A - Improvements in or relating to electro-photographic copying apparatus - Google Patents

Abstract

853,168. Electrophotographic processes. CARIBONUM Ltd. Dec. 16, 1958 [Dec. 19, 19571, No. 39530/57. Class 98(2) [Also in Group XXXV] In an automatic xerographic contact printer, for successively charging, contact printing, powder developing and fixing the powder image on copy paper having a photoconductive insulating layer, the back of the paper is earthed during charging by means of a moving support made of flexible natural or synthetic plastic or rubber. As shown, the paper may be carried, during charging, on a conductive coating of graphite on a plasticised polyvinylchloride endless band 24, a vacuum deposited layer of copper or aluminium on a spongy foam plastic roller covered with smooth polyvinylchloride (Figs. 4 A, B, not shown) or on an endless band of conductive rubber (Fig. 6, not shown). Copy paper and a translucent original are positioned in slots 11 and 12 in contact with fingers 17 and 21. On starting the machine; rollers 15 and 19 are simultaneously pressed towards feed rollers 14 and 18 so that the paper and original are fed in and will arrive in register at transparent rotating printing cylinder 40. The paper is carried past a corona discharge head 22 (see Group XXXV) by belt 24, the graphite layer of which is earthed and maintained by rubbing on earthed graphite roller 31. Belt 24 may be driven by roller 27 of sponge rubber having plastic flanges 28. Contact printing is effected by lamp 47 and, on leaving cylinder 40, the edge of the original, which leads that of the paper by a small amount, is deflected by a timed motion of a separator bar 48 and is guided by plate 49 to tray 50. Alternatively, if the original is to be repeatedly copied on to a web of copy paper, the leading edge is held in a resiliently urged clamping strip pivotally mounted on cylinder 40 (Fig. 6, not shown). The exposed copy paper is guided by brass plate 52 to a -continually renewed magnetic brush 54, charged with toner powder, where it is developed. The operation of the developing section of the machine is described in detail in Specification 853,169. The powder image is fused by means of a current of hot air from an air heater 59. The fused powder is pressed into the paper by a roller 60 having a polished chromium plated surface and co-operating with a scraper blade 62. In another form (Fig. 5, not shown) the paper is heated to fuse the powder by an infra-red lamp which is automatically switched off if the paper should stop moving in front of the lamp. Specification 853,170 also is referred to.