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 meas-

ures 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 devel-

oping bias for use in determining the laser output (LP) needed to attain the target potential.

7.4.5 Determining the Developing Bias

iR5065 / iR 5055 / iR5075 / / /

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)

7-6

Target VD

Fixing assembly temperature 195 C

WMUP

Potential sensor

Grid bias

Primary charging

Potential control

sequence start

Fixing assembly

temperature 195 Deg C