When a photoreceptor is dip coated, the layer thickness increases slowly to a target value after the takeup speed reaches a constant value. The resulting non-uniformity in layer thickness is called “sloping.” “Sloping” of the deposited layer over the imaging area of the photoreceptor is undesirable since it can degrade the performance of the photoreceptor. To prevent the deposited layer from exhibiting “sloping” in the imaging area, one can use a longer substrate to provide a longer non-imaging area so that the “sloping” of the deposited layer occurs only in the non-imaging area while the deposited layer exhibits relatively uniform thickness in the imaging area. However, a longer substrate and a longer non-imaging area increase costs since more materials have to be used in the substrate and the deposited layer or layers. Thus, there is a need, which the present invention addresses, for new methods to eliminate or reduce the above described problem.
Coating methods and apparatus are described in Petropoulos et al., U.S. Pat. No. 5,633,046; Herbert et al., U.S. Pat. No. 5,683,742; Swain et al., U.S. Pat. No. 6,132,810; Petropoulos et al., U.S. Pat. No. 5,578,410; and Crump et al., U.S. Pat. No. 5,385,759.