Ricoh FT6645 Manual page 31

PROCESS CONTROL
1.3.2 Drum Conditioning
When the fusing temperature reaches 180°C, the machine starts the drum
conditioning process. In this mode, the main motor, main charge corona,
erase lamp and development bias are activated for about 30 seconds and
drum sensitivity and residual voltage (V
copy runs.
1.3.3 V Adjustment
SG
During drum conditioning, the ID sensor checks the bare drum's reflectivity
and calibrates the output of the ID sensor to 4 ±0.2 V.
1.3.4 V Measurement
R
[V]
[–V]
Drum
Potential
The above figure shows the relationship between the drum potential and the
original density. To get constant copy quality, this relationship must be
maintained.
Since this relationship tends to change to the one represented by the dotted
line by various factors, compensations are required.
The residual voltage (V
voltage is increased. Therefore, the V
other means.
The main control board checks the drum potential just after the erase lamp
exposure by the drum potential sensor after drum conditioning. This
measured drum potential is in fact V
V and V corrections.
D L
NOTE: In the figure above, the residual voltage (V
0V. Actually, there is some residual voltage even on the new
drum.
V
o
V
D
V
Dark Original Density
) cannot be compensated even if the exposure lamp
R
) are stabilized, as in continuous
R
L
change has to be compensated by
R
. This V is used as the standard for the
R R
2-6
23 April 1993
New Drum
Used Drum
V
R
Light
) for the new drum is
R