GB1223357A - Imaging process - Google Patents

Abstract

1,223,357. Electro-photographic processes. XEROX CORP. April 30, 1968 [May 1, 1967], No.20429/68. Heading G2H. In an electro-photographic method, an imaging plate, comprising a substrate overlaid with a solvent softenable layer containing a homogeneous dispersion of photo-sensitive particles, has a latent electrostatic image of one polarity formed thereon, the plate is then charged uniformly with an opposite polarity and developed in a liquid or vapour solvent or by heat whereby the softenable layer is softened or dissolved and photo-sensitive particles adhere to the substrate in a negative image configuration. The latent image may be formed by uniform charging e.g. with a corona discharger, and imagewise exposure of the softenable layer, or the softenable layer and substrate may be oppositely charged with corona dischargers. If the substrate is non-conducting charging is carried out with the substrate contacting an earthed conductive plate, which may be kept in contact with the substrate during development, or stripped therefrom prior to development. Suitable substrate materials are metals e.g. gold or silver or conductively coated insulators e.g. aluminized plastics. The softenable layer may be, for example a rosin ester, an alkyd or silicone resin, a polyolefin or a polystyrene. The photo-sensitive particles may be inorganic e.g. selenium or organic, e.g. a dye pigment. The solvent for the softenable layer may be e.g. xylene, ethylether, benzene, tolvene, and must be electrically insulating and chosen so as not to dissolve the substrate and photo-sensitive material. In another embodiment, non photo-sensitive particles e.g. carbon black, are used and charging is accomplished via a mask stencil or by using a shaped electrode. In another embodiment additional steps of charging with opposite polarity and uniform exposure to activating radiation are included.