Intermediate transfer member belt/roller configuration for single-pass color electrophotographic printer

The field of electrophotographic (EP) printers, particularly those intended for an office environment, is actively migrating from mono (single color, i.e., black) printers to color printers. In a known type of color EP printer, four stations associated with four colors, yellow, magenta, cyan, and black, are provided. Each station includes a laser printhead that is scanned to provide a latent image on the charged surface of a photoconductive (PC) drum. The latent image on each drum is developed with the appropriate color toner and transferred onto an intermediate transfer member (ITM) belt. The image is accumulated on the belt by passing each of the four color stations in turn. In another known type of color EP printer, each color image is developed separately on a single PC drum and accumulated on the ITM belt by making four passes past the PC drum. From the ITM belt, the image is transferred to a media substrate such as paper or a transparency. In another known type of color EP printer, a sheet of media is carried on a belt past the four stations and the image is accumulated directly on the media substrate. The toner on the substrate is then fused to the substrate in a fuser assembly, and the substrate is transported out of the printer. A single-pass color electrophotographic printer includes four imaging stations, yellow, cyan, magenta, and black, on a generally linear path. A toned image in each toner color is developed on an image bearing member or photoconductive drum. A plurality of electrically biased first transfer rollers associated with each imaging station is operative to transfer the developed images from the photoconductive drum to an intermediate transfer member (ITM) belt that travels sequentially past the imaging stations along the generally linear path in a first transfer operation. The image on the ITM belt is transferred to media at a second transfer operation at which the ITM belt passes through a nip between a backup roller and a further electrically biased transfer roller. A servo operation is used to set the voltages on the transfer rollers. Rollers at the second transfer are positioned to direct media downwardly out of the nip to a media transport belt and to a fuser assembly. A reverse roller is provided downstream of the second transfer operation to shift the path of the ITM belt away from the media guide plate and media transport belt. The ITM belt is formed of a resistive material having a uniform thickness and high tensile modu