PHOTORECEPTOR BELT DRIVE SYSTEM TO ENABLE REAR EXPOSURE FOR MULTIPLE READ STATIONS
Original Publication Date: 1995-Apr-30
Included in the Prior Art Database: 2004-Apr-07
Xerox Disclosure Journal
In an electrophotographic printing machine, typically a surface of the photoconductive member is charged, exposed and subsequently developed with toner particles. Alternatively, the surface may be charged and the surface of the photoconductive member opposed from to the charged surface may be exposed. The first mentioned surface is then developed. This requires that the photoconductive member be substantially transparent. A system of this type would be highly desirable in a single pass multicolor printing machine. In a printing machine of this type, the first surface of the photoconductive member is charged and the second or opposed surface is exposed. Thereafter, the first surface is developed with toner particles of the first color. The process is then repeated for subsequent colors to form a composite multicolor image on the first surface of the photoconductive member which is subsequently transferred to a copy sheet. When exposing in this fashion, exposure energy is not lost due to scattering and absorption by exposing through the developed toner image on the first surface of the photoconductive member. Moreover, the exposure level at the second and subsequent exposure stations is not dependent on the mass and optical properties of the toner image developed at the preceding development station. However, in order to accomplish exposure through the rear side of the photoconductive member, abrading of the photoconductive member must be prevented. Typically, the photoconductive member is a belt entrained about a plurality of rollers for advancement thereby. Thus, it is necessary to prevent abrading of the back surface of the belt. Abrading of the back surface of the belt causes scattering of the incident exposure energy. In order to prevent abrading of the back surface of the belt, a sprocket drive may be used to advance the photoconductive belt. Hydrostatic air bearings support the interior surface of the belt. In this way, the interior surface of the belt does not become abraded.