Brother MFC-9420CN Service Manual page 52

8 Drum Cleaning
Transfer belt cleaning process means that the residual toner on the transfer belt is removed.
(1) Structure of transfer unit cleaner PU (Refer to Fig.3-23.)
1) Transfer unit cleaner PU is located as shown in Fig.3-9.
2) Cleaning brush is a semiconductor type fur brush to clean the surface of transfer belt
as rotating. However, the cleaning brush stays away from the transfer belt while
imaging on the transfer belt.
3) Belt cleaning roller is positively biased by the positive voltage FCBV(V).
4) FCBV(V) is injected to the cleaning brush as well, and the cleaning brush is self-
biased by the resistance of brush.
5) Cleaning roller rotates as contacting to the belt cleaning brush.
(2) Process of transfer belt cleaning (Refer to Fig.3-23.)
1) There is the residual toner on the surface of transfer belt after the paper transfer
process.
2) Cleaning brush is positively self-biased. Cleaning brush has the negatively charged
residual toner fall off from the surface of transfer belt, and electrically absorbs the
residual toner into the belt cleaning brush.
3) Cleaning roller has been biased to the positive FCBV(V), the residual toner absorbed
into the cleaning brush is attracted by the positive FCBV(V) is adhered to the surface
of cleaning roller.
4) Waste toner adhering to the surface of cleaning roller PU is scavenged by the
cleaning blade and collected to the waste toner pack by the waste toner feeder.
Cleaning Brush
Residual
Toner
FCBV
Transfer Belt
Cleaning Roller
Waste Toner Feeder
Drum
Fig. 3-23
3 - 2 0
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