GB1291074A - Colour electrophotography - Google Patents

Abstract

1291074 Electrophotographic material ILFORD Ltd 1 Dec 1970 [8 Dec 1969] S9824/69 Heading H1K In an electrophotographic element for colour reproduction comprising sets of areas which are sensitive to only selected regions of the visible spectrum, the sets of areas are made electrophotographically by exposing a charged photoconductive layer to a pattern of light and developing the pattern with a toner which sensitizes one set of areas corresponding to the pattern to a selected region of the spectrum, this technique being repeated at least once to produce another set of areas sensitive to another region of the spectrum. Each time the technique is repeated the layer is exposed overall to light to which all the areas have been previously sensitized to destroy the charge on the layer in the sensitized areas. This overall exposure may be before, simultaneously with or after the exposure to the pattern of light. The element may be sensitized to three or four regions of the spectrum and the various sensitized sets of areas are equal in area. Screens having opaque lines or lines which are opaque to a region of the spectrum may be used to produce the light patterns and the areas may be arranged as a series of blocks or intersecting lines. The toner is applied as charged particles in the form of a powder an aerosol spray or a liquid and is preferably dye-sensitized zinc oxide particles in an insulating carrier liquid together with an alkyd resin and ferric stearate.