PHOTOCONDUCTOR IMPLICATIONS IN DIGITAL ELECTROPHOTOGRAPHY

The nature of the electrophotographic image when dual-layer organic ph otoconductors are exposed to digital input is different than that of i mages obtained with analog input on account of several considerations: (1) reciprocity, (2) space-charge-limited discharge, (3) optical inte rference effects, and many others. Reciprocity and space-charge-limite d conditions result from short exposure times. Reciprocity refers to t he change in the efficiency of the supply of carriers from the generat or layer into the transport layer. Although, on the basis of theoretic al considerations, there could be either an increase or a decrease of supply efficiency, most published results show a reduction in sensitiv ity. This reduction has been ascribed to Langevin recombination effect s. In the limit of space-charge-limited discharge, there is considerab le lateral motion of the charge carriers (due to their mutual Coulomb repulsion) during their transit through the transport layer, resulting in loss of resolution, which can also occur in analog exposure throug h electric field distortion during exposure. Coherent light interferen ce leads to a print pattern in the background.