IMAGING MEMBER AND METHOD
Original Publication Date: 1977-Oct-31
Included in the Prior Art Database: 2004-Mar-30
Xerox Disclosure Journal
An imaging member capable of the preparation of multiple copies of an original object with only one exposure step and a method for utilizing the member are described. The member consists essentially of a conductive substrate, a persistent photoconductive insulating layer and an electrically insula-ting overlayer. A developable electrostatic latent image is formed by imagewise exposing the member with activating radia-tion and charging the member such as with a corotron to a constant surface charge. The exposure step is carried out with image information at a wavelength and for an interval sufficient to render the persistent photoconductive layer per-sistently conductive for a prolonged period of time, typically at least about 60 seconds and preferably significantly longer, subsequent to the termination of illumination. The exposure may be prior to, simultaneous with or after the charging step. Optimally the exposure step is carried out after the charging step. There is thus generated on the surface of the member a contrast potential sufficient for the formation of a visible image. The magnitude of the contrast potential is related to the relative thicknesses and dielectric constants of the per-sistent photoconductive layer and the electrically insulating overlayer. The electrostatic latent image can be developed by any of the known xerographic development techniques. Multiple reproductions of the same original object may be made without any additional exposure steps as long as recombination life-time of the photo-induced carriers in the persistent photocon-ductive layer permits. This may be on the order of minutes or hours.