Ricoh FT6645 Manual page 27

PROCESS CONTROL
1.1.1 Latent Image Control
The figure shows the changes of the drum potential during the copy process.
Vo:
V (Dark Potential):
D
V (Light Potential):
L
V (Residual Voltage):
R
After long usage following installation or a PM, drum potential will gradually
increase due to the following factors:
Dirty optics or exposure lamp deterioration
Dirty charge corona wire and grid plate
Change of the drum sensitivity
In this copier, the change in drum potential is detected by the drum potential
sensor and the following items are controlled to maintain good copy quality.
The grid bias voltage
The exposure lamp voltage
The development bias voltage.
A drum thermistor detects the drum temperature and this data is also used to
control the above voltages. It is impossible to explain simply because it is
controlled by methods developed in our laboratories using an artificial neural
network.
Q Charge
L
The drum potential just after charging the drum.
The drum potential just after exposing the black
pattern (V
The drum potential just after exposing the white
pattern (V
The drum potential just after the exposure of the
erase lamp.
Exposure
Black White
Vo
V
D
pattern)
D
pattern)
L
2-2
23 April 1993
Erase
Potential
Sensor
V
R
V
L
Drum