Ricoh A172 User Manual

2.2 TONER DENSITY CONTROL
2.2.1 V
CNT
CORRECTION
Even if the toner concentration is constant, the toner density sensor output
gradually increases after new developer is installed because of developer
characteristics. Because of this, the machine believes that the amount of
toner in the developer has reduced. This causes the machine to increase the
toner concentration because the machine controls the toner concentration so
that V
T
stays constant.
To compensate for this, the V
CNT
gain is corrected by using the
development gamma curve made from the 14-grade pattern during process
control self check.
The present gamma curve [A] and the previous gamma curve [B] are
compared, and the average [C] is calculated. As shown in the diagram, the
gain is decreased by 1 when the average gradient is 3.8 or more. The
maximum compensation value is –16.
Because of this new V
CNT
correction system, the V
CNT
correction previously
performed every 200 copies is no longer necessary. Also, due to the use of
the average value, over-reduction of the gain is avoided.
V
T
2.5
Copies
Drum Potential
Pattern Densit
y
(
m
g
/cm
2
)
[A]
[C]
[B]
Gain Value = –1
Gain Value =
±
0
Gain value = +1
Average
≥
3.8
Average
≤
2.3
Toner Density Detailed
Descriptions
SM 2-7 A172/A199

Ricoh A172 Specifications

General

Brand	Ricoh
Model	A172
Category	All in One Printer
Language	English