SERVICE MANUAL - O. Rensch OHG

(3-2) Drum surface potential
The laser beam is continually switched on and off depending on the print data. It is on for a black (exposed) dot and off
for a white (blank) dot. Since the drum surface is evenly charged, whenever it is illuminated by the laser beam, the
electrical resistance of the photoconductor is reduced and the potential on the photoconductor is also lowered. Resulted
on the drum surface is an electrostatic image which represents the data to print. Note that the area to be printed black
has the low potential, constituting a “positively exposed” image.
2DC
Laser beam
Exposed surface potential
approximately +60 to +80 V
Charged surface potential
+400±15 V
OPC
layer
Aluminum
cylinder
Drum
Figure 2-1-13 Drum surface potential
2-1-13