Overview - Ricoh B202 Service Manual

PROCESS CONTROL
6.2 PROCESS CONTROL

6.2.1 OVERVIEW

This machine provides the following two forms of process control:
• Potential control
• Toner supply control
The process control facilities of this machine have the following features:
• Three ID (image density) sensors (front, center, and rear). Only the center ID
sensor is used for process control. All ID sensors are used for line positioning
and other adjustments.
• TD sensor.
6.2.2 POTENTIAL CONTROL
Overview
Potential control controls development to maintain the density of the toner images
on the drums. It does this by compensating for variations in drum chargeability and
toner density.
The machine uses the center ID sensor to measure the reflectivity of the transfer
belt and the density of a standard sensor pattern. This is done during the process
control self check.
The machine determines the following depending on the ID sensor output and a
reference table in memory.
• V
: Drum potential without exposure. The machine adjusts the charge roller
D
voltage to adjust this.
• V
: Development bias
B
• V
: Drum potential at the strongest exposure. The machine adjusts the laser
L
power to adjust this.
(In addition, V
REF
This process controls the development potential so that the maximum amount of
toner given to the drum is constant. However, the laser power control method can
be changed to control the development potential to improve reproduction of
highlight parts of images. This depends on the setting of SP3-125-2. The default
setting is "Process Control". Set this SP mode to "LD Power" if you want to change
the highlight range control method.
If SP3-125-1 is set to "Off", the machine does not do the potential control. Instead,
the machine uses the following:
• Development bias adjusted with SP2-201-1 to –9
• Charge roller voltage adjusted with SP2-001-1 to
• Laser power selected with SP2-103-1 to -27.
You should not adjust these SP modes in the field.
B202/B178/B180
is corrected. This is used for toner supply control.)
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6-8 SM