A Model to Describe Electrographic Development of Resistive One-Component Toner Systems

A phenomenological model is presented which describes the electrographic development of very resistive one-component magnetic toners on a charged photoconductor surface. The model, based on field emission and space charge limited effects, gives a possible qualitative description of the physics involved in the developer nip region for one embodiment of the process described in Nelson´s US Patent 4 121 931. The toners used for these machines are more resistive than many toners used in two-component toner systems. Because the toners are so resistive, a simple electrical induction process for toner development is inadequate in describing the physics of the process. Furttermore, a simple triboelectric mechanism for charging the toner is insufficient to describe the process. The basic model assumptions, along with pertinent supporting data, will be presented. Intrinsic toner properties, such as conductivity, flow characteristics, triboelectric characteristics, and magnetic characteristics also will be included, along with the effect of these properties on image density and image sharpness.