Ricoh FT6645 Manual page 32

23 April 1993
1.3.5 V Correction
D
Exposure
Glass
Drum
V Pattern
Potential
D
The drum potential just after the black pattern (V
Dark Potential) tends to lower during drum life due to a decrease in the
drum's capacity to carry a charge.
To check the actual V
V pattern (Black) stuck on the bottom side of the exposure glass bracket is
D
exposed on the drum.
The main control board measures V
adjusts it to a target value by adjusting the grid bias voltage (V
On the other hand, there is a change of the drum residual voltage (V
that the target V
D
Target V Value: V
D
The adjusted grid bias voltage (V
process control data initial setting.
[-V]
–770
Dark
, the first scanner moves to the home position and the
D
voltage is compensated as follows:
= V + (–770)
D R
GRID
V
D
V
R
New Drum
Original Density
Pattern) is exposed (V
D
through the drum potential sensor and
D
) is kept in memory until the next
2-7
PROCESS CONTROL
V Compensated
D
After many copies
V
D
).
GRID
), so
R
R
Light
: