GB982285A - Process for the production of electrophotographic continuous-tone images - Google Patents

Abstract

982,285. Electrophotographic processes. AGFA A.G. April 30, 1963 [May 19, 1962], No. 16989/63. Heading G2H. [Also in Division H1] An electrophotographic process for producing images comprises charging a photo-conductive layer, exposing the charged layer to the original to be reproduced, thus producing a latent electrostatic image, subjecting the layer carrying the image to a second charging, the product of the voltage and duration of which is from 0.1 to 0.01 of that of the first charging and developing the image with a coloured electrically charged aerosol. In one example, a sheet carrying a photo-conductive layer is placed on an earthed metal plate and is charged for 20 seconds by a needle electrode 180 mm. above the centre of the plate with a voltage of 20 Kv between the electrode tip and plate. The photo-conductive layer is then exposed for two seconds in contact with a continuous tone transparent positive. The original is removed and a second charge is applied to the layer for 0. 5 seconds in the dark at the same voltages. The latent image is developed by an aerosol applied to the layer through a grid-shaped developer electrode. The developer liquid may be a saturated solution of Brilliant blau CC in benzyl alcohol. The second charging may be carried out in several separate steps and the image may be developed between these steps. Specifications 834,502, 874,133, 883,783 and 896,610 are referred to.