Browse Prior Art Database

Original Publication Date: 1985-Feb-28
Included in the Prior Art Database: 2004-Apr-04

Publishing Venue

Xerox Disclosure Journal


Previously, in the development system of an electrophotographic printing machine, it appeared that the dynamic conductivity of insulating single component toner particles was due to charge transport through the development region. Recent experimental results indicate that this phenomena, at least in part, is due to toner particle charge exchange adjacent the photoconductive surface. Jostling between adjacent toner particles in this region permits charge exchange so as to neutralize electrostatic fields. By way of example, an applied positive bias to a developer roller generates a positively charged toner adjacent to the photoconductive surface and negatively charged toner particles beneath the photoconductive surface. The positive toner particles are captured by the electrostatic latent image with the negative toner particles being retained on the developer roller and subsequently neutralized. The situation is further complicated by reverse fringe fields at the edges of the electrostatic latent image and the difficulty in controlling the residual negatively charged toner particles after the positive toner particles are captured by the latent image. Another complication is a concentration phenomena due to the relative velocity of the photoconductive surface and the developer roller. The exit rate of the negatively charged toner particles differs from that of the positively charged toner particles. This results in a net charge which limits the background control latitude.