To measure the light area potential (VL1) for the first time after the power switch is turned on, the machine uses the most recent laser output level (LP0),

and measures the drum surface potential using the potential sensor. The DC controller PCB compares the drum source potential and the target potential;

if the measured potential is +/-10V of the target value, the machine corrects the potential of the laser output, and measures the potential once again. The

machine executes potential measurement a maximum of 8 times, and also corrects the lower output level as many times. In addition, the machine measures

the light area (VL2) for the developing bias for use in determining the laser output (LP) needed to attain the target potential.

7.4.5 Determining the Developing Bias

The machine determines the developing bias (VDC) as follows with reference to the drum surface potential (VL2):

VDC = VL2 + delta VDC

For copier potential, delta VDC=110 V

For printer potential, delta VDC=85 to 110 V (i.e., the printer potential varies to suit the reading of the environment sensor, thus ensuring the reproduction

of correct line width)

7-8

Target VD

Fixing assembly temperature 195 C

WMUP

Potential control

sequence start

Fixing assembly

temperature 195 Deg C

WMUP

Potential sensor

Developing bias