Cartridge Primary charging roller Laser beam Blade Cleaning blade Developing cylinder Photosensitive drum Static charge eliminator Transfer charging roller Figure 40. Toner cartridge Photosensitive drum The photosensitive drum is the heart of the image formation system. This drum’s special properties allow an image to form on the drum's surface and then transfer to paper. The drum is an aluminum cylinder coated with an organic-photoconductive material (OPC). The photosensitive drum’s aluminum base is electrically connected to ground. The OPC material becomes electrically conductive when exposed to light. Areas not exposed to light remain nonconductive and maintain their negative charge.
Figure 41. Photosensitive drum Cleaning stage At the cleaning stage, the photosensitive drum's surface is prepared to hold an image. During printing, the drum rotates completely several times per printed page. Before forming the image for a given section of print, a cleaning blade removes toner from the previous rotation of the drum. The toner cartridge stores waste toner and prevents it from being used in later print jobs. C7058-90936 Printer functionality and operation 81