Electrophotography (also called xerography), the technology inside the famil iar copier, has become increasingly important to modern society. Since the first automatic electrophotographic copiers were introduced in 1959, they have become indispensable to the modern office and now constitute a multi billion dollar industry involving many of the world's largest corporations. By the 1990s, it is expected that electrophotography will be one of the most pre valent printer technologies. This will occur because of the growing need for printers that are quiet, that can produce multiple fonts, and that can print graphics and images. Electrophotographic printers satisfy these requirements and have demonstrated economic and technical viability over an enormous speed range, from 6 to 220 pages per minute, with output quality that ap proaches offset printing. Organizations contemplating designing a new electrophotographic copier or printer need to deal with two sets of issues. First, for each of the six process steps in electrophotography there are several different technologies that must be evaluated and chosen. For example, there are three development technol ogies (dual component, mono component and liquid); cleaning can be done with a blade or brush; and the photoconductor can be inorganic or organic, either of which can be configured in the form of a belt or a drum. Second, once a technology for each step is chosen, it must be optimized and integrated with the other process steps. This optimization and integration is facilitated by a firm scientific understanding of the technologies being considered.