Oce 3121 Technical & Service Manual page 194

Pre-exposure
1
Charging (AC + negative DC)
2
laser exposure
3
Development (AC + negative DC bias)
4
Transfer (positive DC)
5
Separation (negative DC)
6
Fusing
7
OPC cleaning
8
The OPC has a layer construction. The outer layer is a photo-conductive layer
of OPC. The inner layer is a conductive aluminium substrate.
Formation of the latent image
The image creation is in three phases. Ultimately, negative charges remain on
the OPC in the areas where the document is white. The negative charge is dis-
sipated in those areas which correspond with the black areas on the document.
These images on the OPC, created by the negative charges, are invisible to the
human eye. They are referred to as static, or latent images.
Surface
potential (V)
-500
-1000
ed.1
photoconductive layer
Photoconductive layer
substrate
Substrate
Time (t)
Light areas
(dark areas of originals)
Dark areas
(areas not exposured by the laser)
Laser exposure (step 3)
General operation 5