Latent image changes during electrophotographic development

Abstract

The latent image formed at the surface of a photoconductive layer is leveled out during the time of development by means of charge neutralization, due to the finite conductivities of the surrounding media. The representation of the charge distribution in terms of its spatial frequency components, and the assumption of the currents at the image surface being proportional to the local electric field associated, yields an exponential decay of each component. The corresponding ’’spectral time constants’’ derived determine the rate of decrease and the degree of spread of the charge and field distributions with increasing time. Their dependence on the parameters of the electrophotographic system is governed both by static and dynamic boundary conditions. Numerical results for periodic line charge patterns are presented, varying in spatial frequency and electrode spacing. As can be predicted from the frequency dependence of the spectral time constants the charge and field distributions are smeared out remarkably in the case of low spatial frequencies and large electrode spacings. It follows that an edge enhancement will be compensated soon after immersion of the image surface. The resultant time scale is essentially defined by the effective conductivity at the boundary layer.