To measure the dark area potential (VD) for the first time after the power switch is turned on, the machine uses the most recently measured current level, and meas-

ures the drum surface potential using the potential sensor. The DC controller PCB compares the drum surface potential and the target potential; as a result, if the

measured potential is +/-6 V of the target value, the machine corrects the primary current and measures the potential once again. The machine executes potential

measurement a maximum of 8 times, and also corrects the primary current as many times.

7.4.4 Determining the Laser Output

iR5065 / iR 5055 / iR5075 / iR5075N / iR5065N / iR5055N

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 / iR5075N / iR5065N / iR5055N

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