Modelling dielectric heterogeneity in electrophotography

We introduce a continuum model of electrophotographic printing of paper and other disordered composite films. The model allows simulation of any dielectric distribution within a toner transfer gap. It is used to elucidate the role of mass density and paper thickness variations on toner transfer efficiency in Xerographic printing. Our simulations show that spatial variations in inorganic filler distribution within paper as well as paper thickness variations will strongly affect toner transfer uniformity by controlling the point-to-point variation of the local dielectric constant of paper. This variation will manifest itself as a mottle in toned images. It is specifically shown that paper thickness variations in paper lead to toner density variation on the scale of 1 mm, similar to those found in Xerographic printing of commercial papers.