GB1281235A - Electrostatic image transfer - Google Patents

Abstract

1281235 Transferring electrostatic latent images RANK XEROX Ltd 24 July 1969 [26 July 1968] 37323/69 Heading G2H An imaging process for producing multiple copies comprises forming a latent electrostatic image on a photo-conductive plate insulating layer 22 having a light fatigued resistivity in the range from 10<SP>8</SP> to 10<SP>13</SP> ohm-cm, and contacting the image surface with the uniformly charged surface. of an insulating layer 35, increasing the field between surfaces and then separating the surfaces to transfer selectively transfer charges between the surfaces to produce an electrostatic image on the insulating layer conforming to that on the photo-conductive layer 22. A potential is applied to the layer 35 by a corona device 24, Fig. 5 such that air breakdown decends in the air-gap between layers 35 and 22 which modifies the negative charge on the layer 35. Due to persistent conductivity of exposed areas of the layer 22 the negative charges in the exposed areas will be dissipated and the original image on the layer 22 will be recovered. The insulating layer may be, for example, of cellulose acetate, ethyl cellulose, polystyrene, polyethylene, polyvinyl chroride, insulating paper or polytetrafluoroethylene. Examples of photo-conductive materials are lead oxide, zinc oxide, cadmium sulphide, and arsenic selenium alloy. The latent image formed on the layer is developed in known manner e.g. g. in a rocking tray, Fig. 6 (not shown) and then heat fixed. Multiple copies may be formed on separate insulating layers without reimaging the photoconductive layer.