GB1066249A - Xerographic charge transfer process - Google Patents

Abstract

1,066,249. Transferring electrostatic images. GENERAL ANILINE & FILM CORPORATION. Nov. 19, 1963 [Dec. 28, 1962], No.45627/63. Heading G2H. In order to provide a temporarily conducting interlayer in a charge receiving sheet for use in effecting a latent electrostatic image transfer, under conditions of very low relative humidity, a photo-conductive insulating layer or laminar zone underlies the charge receiving surface and is uniformly exposed to actinic radiation immediately prior to transfer. As shown in Fig. 1, a photo-conductive insulating layer 32 contains zinc oxide produced by the French process and underlies an insulating resin layer 33 which may contain a pigment such as mica, silican or titania. Both layers are supported on a paper or plastic film base 31. The layer 32 is made conductive by passing the strip beneath a fluorescent lamp 25. The conductivity is retained while the layer is earthed at 69 and an electrostatic latent image is transferred from photo-conducting insulating layer 37, under the influence of an electric field from high voltage generator 39a.. The charge image 42 on layer 33 is subsequently developed and fixed. In Fig. 4 (not shown) the insulating resin layer is omitted and the photo-conductive insulating zinc oxide layer 32" is so absorptive at the wavelengths used for exposure, that only the part of the layer nearer the lamp 25b is made conductive. The transfer of charge is effected by bringing the photo-conductive layers 37' and 32" into contact. In another form, Fig. 7 (not shown) the receiving strip is charged prior to transfer and the transferred image is developed with a liquid toner and fixed by drying with a current of warm air. In a further form Fig. 6 (not shown), in which the primary image is formed electrically on a rotary cylindrical surface, the residual charge is removed from this surface by wiping it with a sponge roller dipping into a container of earthed conductive liquid. A method of exposing the strip prior to image transfer, to a dot pattern on a transparent cylinder is described. The resultant image is stated to be of use in the preparation of half-tone plates. Several constructions of sheet material are described and in one of these the base layer 36 is used as the image receiving layer. In another construction the photo-conductive zone is formed in a paper base layer by impregnating one face of the paper with photo-conductive material. This face is then coated with a charge receiving insulating layer.