Abstract: An illumination control system for electrographic apparatus of the type utilizing a reusable photoconductive insulator member that changes in electro-photosensitive properties during the period of its useful life. The system includes a device for sensing and storing usage information about such member, for providing signals representative of cumulative usage of the member and for increasing the exposure of the member in accordance with a non-linear schedule which corresponds to photochemical, sensitometric changes that occur in the member with increasing cumulative usage.

Abstract: An electrophotographic apparatus having improved structure and procedures for regenerating electrophotosensitive properties of its photoconductive imaging member. Erase lights, of spectral quality matching peak absorption characteristics of the imaging member, are located to enable their radiation to be strongly absorbed proximate the positively biased surface of the imaging member. The regenerative sources are provided at locations around the copying path which cause relief of field load on the photoconductor during each cycle, soon after its useful function has been accomplished.