GB1277233A - Electrophotography - Google Patents

Abstract

1277233 Multi-colour electro-photographic apparatus CANON K K 10 June 1969 [12 June 1968] 29361/69 Heading G2H An electro-photographic apparatus for reproducing multi-colour originals has an electrophotographic drum 13 which is exposed to an original 16 to form a latent image of a selected colour content of an original, developing apparatus for developing the latent image with a corresponding coloured developer i.e. the same colour or a complementary colour, means for transferring the developed image to an intermediate member 26, means for causing these steps to be repeated for other colours of the original and transfer means for transferring the composite coloured image from the member 26 to an image member 30. The drum 13 has a substrate 1, a photoconductive layer 2 and an insulating layer 3 laminated one upon another. In another embodiment of image member Fig. 2 (not shown) insulating layer (3) and (3)<SP>1</SP> are formed on either side of a photo-conductive layer (2). The substrate 1 may be a metal such as copper, tin, or aluminium or paper with an aluminium coating. The insulating layer may be organic high molecular compounds, e.g. fluororesins, polycarbonate resins or polyethylene or inorganic compounds, e.g., Al 2 O 3 , Si O 2 Ti O 2 or BN. A corona charger 14 uniformly charges the insulating layer 3 before exposure to the original 16 through a filter 20 e. g. a blue filter. A second corona charger 15, which may be an A.C. charger, charges the layer with an opposite polarity during exposure. The image area is then uniformly illuminated by a lamp 21 to increase contrast. The latent image is then developed with yellow toner and transferred to drum 26. The residual image is removed from the drum 26 and the process is repeated using a red filter and cyan toner, and than a green filter and magenta toner. The composite image on the drum 26 is then transferred by a pressure roller 32, to member 30 which may be of fabric. The developers may be dry, e.g., a cyan toner may include polystyrene and an oil soluble metal complex dye such as "Orasol" (Trade Mark) Brilliant Blue or polystyrene and an acid dyestuff such as Kayacyl (Trade Mark) Blue, magenta toner containing polystyrene and Kayanol milling Red; and yellow toner containing polystyrene and Kayacyl Yellow. Liquid developer may contain linseed oil and lead chromate dispersed in an insulating liquid, such as a pentane or carbon tetrachloride, Isopar H (Trade Mark) or linseed oil and cadmium selenate dispersed in n-pentane, or linseed oil and phthalocyanine blue dispersed in n-pentane. Specifications 1165405 to 1165410 are referred to.