Simulating digital exposure of xerographic photoreceptors using the domain-decomposition method

In digital electrophotography, the photoreceptor (PR) is discharged by exposing it to a high-intensity laser beam from an imager for a very short duration in an imagewise fashion. The resultant latent image on the PR surface is a function of the PR properties, the imager properties, as well as the spatial and temporal exposure sequence. A generalized computational model for discharge based on charge generation, injection, and transport in a PR has been discussed previously (Proc. SPIE, vol. 2658, p. 112, 1996). In this paper, the use of the domain-decomposition method to enable an efficient simulation of a latent image for wide-area exposures (such as wide lines and solid areas) is discussed. A photo-induced discharge curve (PIDC) with a multibeam imager is simulated using this algorithm. The simulation results show that laser exposure sequence can create an inhomogeneous field on the generator layer, which may lead to varying amounts of charge injected at the generator layer for the various scan lines. However, the impact on the discharged image is reduced since charges in transit appear to reequilibrate spatially. The photo-induced discharge is somewhat less efficient (10-15 V for exposures greater than 5 ergs/cm² for results presented here) due to a two-beam interlaced exposure sequence compared to the case when all the pixels are exposed simultaneously. Simulation results for discharge of lines show that narrow positive lines grow due to the field dependence of collection efficiency during charge generation and subsequent spreading of charges in transit. A single-pixel positive line, for instance, can grow as much as 40%. The effect is less pronounced for wide lines.