DRUM UNIT
SM 6-79 B234/B235/B236/D101/D102/D103
Detailed
Descriptions
Auto Process Control Flow
Step 1
Charge Unit Corona Wire Cleaning
↓
Step 2
Process Control Begins (OPC Drum Start Timing)
↓
Step 3
ID Sensor Vsg Adjustment
↓
Step 4
Vb (Development Bias Voltage), Vg (Charge Grid Voltage),
LD (Laser Diode) Power Adjustments
(Based on Drum Potential Sensor Readings)
↓
Step 5
TD Sensor (Vref) Adjustment
(Based on ID Sensor Readings)
↓
Step 6
Vb (Development Bias Voltage), Vg (Charge Grid Voltage)
Adjustments (Based on VL Detection)
↓
Step 7
Process Control Ends
Vsg Reflectivity of the bare surface of the drum. This reading is used
with Vsp (the reflectivity of the ID sensor pattern where it is covered
with toner) to calculate Vref (Vsp/Vsg).
Vb Development bias. A charge applied to the drum to prevent dirty
backgrounds on copies. Backgrounds emerge dirty if the residual
potential (Vr) remains high.
Vg Voltage output of the charge corona unit. Vg is used to adjust Vd,
the drum potential of the unexposed areas of the drum.
Vh Standard drum potential for halftone.
VL Light potential, the drum potential after maximum laser exposure.
The drum potential sensor measures VL by reading the white
patches of the potential sensor pattern. To change VL, the machine
adjusts input current of the laser diode.
Vd Detected by the drum potential sensor, this is the reading of the
drum surface before it is exposed by the laser. This is the "dark
potential".
Vdref The target value of Vd, the dark potential of the drum before it is
exposed by the laser.
LD PM Laser Diode Pulse Modulation. This is strength (intensity, amount of
light) of the laser beams.
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