Ricoh FT5233 Service Manual page 38

12 February 1992
1.3.3 V Correction
R
V level Vrp/Vrg x 100(%)
R
0 100~84
1
2
3
4
When calling SP mode #54, the reference voltage of the V sensor output Vrg
is automatically adjusted to 4V at the same time as Vsg is adjusted.
The grid bias voltage and the development bias voltage are corrected (V
correction) according to the ratio between Vrp and Vrg as shown in the above
table.
(ex. If there is no residual voltage on the drum, Vrp=4V and Vrg=4V. Then
the proportion is: Vrp/Vrg x 100 = 4/4 x 100 = 100%)
When the drum residual voltage increases, the V
The value of Vrp decreases and also the Vrp/Vrg ratio decreases. Then the
CPU increases the negative development bias voltage to prevent a dirty
background, and simultaneously increases the negative grid bias voltage to
prevent low image density.
Grid bias correction
83~58
57~41
40~28
27~0
2-9
PROCESS CONTROL
Development bias
voltage correction voltage
± 0 V
– 40 V
– 80 V
– 120 V
– 160 V
pattern becomes darker.
R
± 0 V
– 40 V
– 80 V
– 120 V
– 160 V
,
R