Brother HL-4000CN, Service Manual

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III-4
1.3 Description of Printing Process Techniques
1.3.1 Charging with electricity
In the charging process, the drum surface rotating at a constant speed is charged
uniformly with negative electricity by discharging of HTC (Hechima Tube Charge:
Charged film).
This process is performed in parallel for yellow, magenta, cyan and black colors.
•
The HTC is kept in contact with the drum and rotates following the rotations of the
drum.
HTC is a conductive roll, receives discharge voltage from HVPS (High Volume
Power Supply) and discharges at minus DC voltage.
•
The drum surface is uniformly and negatively charged with DC bias voltage.
The drum surface is optical conductor (which is insulator in a dark place and
conductor when receiving light) and the drum inside is composed of conductor.
•
The Refresher is a conductive brush, and it receives negative DC voltage from the
HVPS to catch the toner of reverse polarity returned to the drum via IDT. Also, it
removes discharge products.
-
+
-
-
+
+
-
-
-
HTC
Refresher
HVPS
Optical conductor
Conductor
Drum
Fig.3-4
Drum surface
Fig.3-5
Electric potential
on drum
-V
0
Fig.3-6