GB807079A - Improvements in electrostatic printing - Google Patents

Abstract

807,079. Electrophotographic processes. GENERAL DYNAMICS CORPORATION. Feb. 21, 1957 [March 19, 1956], No. 5921/57. Class 98(2) An image is formed on an electrically insulating surface by supporting it on an electrically conductive backing material and contacting its surface, either directly or through an intervening layer of insulating liquid, with the surface of a photoconductive layer on an electrically conductive support, forming an electrostatic charge pattern of the image to be reproduced on the surface of the photoconductive layer either before or after contact with the insulating layer, connecting the electrically conductive backing layers so that they are both at the same potential, and then separating the photoconductive and insulating layers and developing the image on the insulating layer. The photoconductive material may be given a uniform electrostatic change followed by imagewise exposure before it is contacted with the insulating layer. Alternatively, the insulating layer may be given a uniform electrostatic charge and the layers assembled in contact. The backing layers are then connected to the same potential and the photoconductive layer exposed through its conducting backing, which must of course be transparent. When the layers are contacted through an intervening layer of insulating liquid, the latter may be a silicone oil, and this may be applied to the photoconductive layer prior to charging. The insulating material on which the image is formed may be a polyester terephthalate plastic film, which may be attached to aluminium foil as a backing. Specifications 672,767, 755,486, and U.S.A. Specification 2,693,416 are referred to.