GB842032A - Improvements in or relating to copying apparatus - Google Patents

Abstract

842,032. Electrophotographic apparatus. ZINDLER, W., [trading as LUMOPRINT ZINDLER KOMM.-GES.] Oct. 7, 1957 [Oct. 22, 1956; Nov. 16, 1956], No. 31367/57. Class 98(2) An electrostatic latent image is developed by passing it under a magnetic device which is moved relative to the image and supplied with developer from a distributer device, the developer comprising magnetic carrier particles which adhere to the magnets and form "brushes", and toner particles which are transferred to give the developed image. The magnets may be in the form of rollers, of bar magnets supported horizontally from the face of a vertical disc, or of bar magnets on an endless conveyer band. The rollers may comprise a series of bar magnets with their centres on the roller axis, the magnets being parallel to each other or arranged in star fashion. The poles of the magnets may be in an outer cylindrical surface of non-magnetizable material. Alternatively, the magnetic roller can comprise ring-shaped or sector shaped magnets. In the case of magnets on a conveyer band, this may travel either parallel to or perpendicular to the direction of travel of the latent image, and both sides of the band may pass across the image surface or one side over and one under the image surface. The band may pass across the surface in a curved path. Apparatus is described for performing all the steps of producing a fixed, developed image on a xerographic sheet comprising a photoconductive layer. In Fig. 1, the xerographic sheet is inserted in slot 3 wherein it receives a uniform charge, exposed under plate 13 by lamps 11, through a master inserted at 2, and passed to the developer unit comprising parallel bar magnets 21 spaced along a core 20 and having their poles in an outer cylinder 33. Carrier particles adhere to the magnets and pick-up toner from the distributer 18 and transfer it to the latent image. Auxiliary magnets 23 make the "brushes" of carrier particles stand up again after being flattened by contact with the image. The developed sheet passes, to the fixing unit comprising a heated plate 25 to which it is held by suction from a blower 28. Additional radiators 30 and reflectors 31 may be provided. In the apparatus shown in Figs. 3 and 5, the xerographic sheet is inserted at 42, charged at 44, exposed by a lamp 47, and thereafter held on its guide path through the developer and fixing units by air sucked through holes 54, 82 by suction pipe 85. The developer unit comprises bar magnets 62 mounted on a rubber belt 61 which passes round rollers at each end so that the magnets on both sides of the belt pass across the xerographic sheet 63 to be developed (Fig. 5). Toner powder is supplied from distributers 69, 70, and directed on to bar magnets 62 by additional magnets 75, 76. The developed image is fixed in the heated chamber 41.