Ricoh A085, Manual

Page: 264 / 617

1.3.3 V
R
Correction
V
R
level Vrp/Vrg x 100(%)
Grid bias correction
voltage
Development bias
correction voltage
0 100~84
±
0 V
±
0 V
1 83~58 – 40 V – 40 V
2 57~41 – 80 V – 80 V
3 40~28 – 120 V – 120 V
4 27~0 – 160 V – 160 V
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
R
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
R
pattern becomes darker.
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.
Det
a
il
ed
Descriptions
12 February 1992 PROCESS CONTROL
2-9