Electrophotographic Behaviour of Two-Layer Structure Consisting of CdS-Resin and Insulating Layers

Abstract

Electrophotographic behaviour of a plate having two-layer structure consisting of a CdS-resin and an insulating layers is investigated. Three processes are used in which positive corona discharge is commonly applied at Step 1. Process 1 and Process 2 are different in Step 2, as negative corona discharge and ac corona discharge are used respectively with simultaneous exposure. Process 1 is better to obtain high contrast voltage than Process 2, even if the same plate is used. This is ascribed to the fact that Process 1 can widen the surface potential of the plate over its saturation potential. Process 2 does not give the contrast voltage difference between two plates with different properties, although Process 1 clearly distinguishes these plates from each another. The relationship between light part and dark part of surface potentials at Step 2 in Process 1 is opposite to that in Process 2, although the relationship is the same at Step 3. When plates are not charged to show their saturation (acceptance) potentials at Step 1, those behave differently, depending on whether the plates are charged with simultaneous light image projection soon after Step 1 (Process 1) or after uniform illumination following Step 1 (Process 3). Properties of photoconductors are investigated and the behaviour difference between plates is analyzed.