Oce 3121 Technical & Service Manual page 195

Pre-Exposure
Prior to charging, light from the pre-exposure lamp is directed onto the surface
of the OPC. This removes any residual charges, later preventing uneven copy
density.
Primary Charging
primary charging roller
Primary charging roller
The charging roller is a conductive rubber. The use of direct charging requires
a lower application voltage that the conventional corona charging system. Al-
so, it produces almost no ozone.
An AC bias is applied to stabilise the charges applied to the photosensitive
drum.
The primary charging roller is a special roller and is not the same as the transfer
roller.
Laser Exposure
laser light
Laser light
dark area light area
Dark area Light area
A laser beam, containing the darker areas of the document image, is directed
onto the surface of the OPC. This neutralises the charges. The areas of this la-
ser image on the OPC will later attract toner, during the development phase.
6 TSM Océ 3121 General operation