| 摘要 |
940,577. Electrophotography. AGFA A. G. Nov. 4, 1960 [Nov. 5, 1959], No. 38021/60. Heading G2H. [Also in Division H1] In the production of electrophotographic images by imagewise discharge by light of a charged photo conductive layer, this layer is charged non- homogeneously and the charge image is developed with a toner which has not been subjected to a charging treatment and which has a high electrical polarisability. Non-uniform charging prior to exposure may be achieved by one of the following: (1) using a charging field that causes local disruption of the photoconductive layer e.g. 7 to 15 kV for a 10 to 30 Á layer of zinc oxide in silicone resin; (2) including dispersed materials of lower conductivity than the photoconductor; (3) employing a photoconductive layer with an irregular or patterned surface; (4) using a photoconductive layer with a surface having irregular electrical, e.g. tribo -electrical, properties. The toner may be of conductive materials such as carbon black, graphite, or conductive pigments or dyes or may be particles of an insulating material coated with antistatic compounds. A specific example is a bitumen-graphite toner treated with a phosphoric acid ester wetting agent or an aqueous dispersion of a stearic acid ester.
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