Ricoh FW780 Service Manual - Page 37

1. DRUM 1.1 DRUM CHARACTERISTICS The organic photoconductor (OPC) drum has the following characteristics: • It is able to accept a high negative electrical charge in the dark. (The electrical resistance of the OPC drum is high in the absence of light.) • The electric charge on the drum surface dissipates when the drum is exposed to light. (The conductivity of the OPC drum is greatly enhanced by exposure to light.) • It dissipates an amount of charge that is in direct proportion to the intensity of the light. That is, where stronger light is directed to the photoconductor surface, a smaller voltage remains. The OPC drum used in this model has high sensitivity, good color reproduction, and good reproduction of low contrast originals (pencil originals, etc.) A163 2-1 SM