2BT
2-1-11
(1) Formation of magnetic brush
The developing roller consists of a magnet roller with five poles and a sleeve roller. Rotation of the sleeve roller around
the magnet roller entrains developer, which in turn forms a magnetic brush at pole N1 on the magnet roller. The height of
the magnetic brush is regulated by the doctor blade; the developing result is affected by the position of the poles on the
magnet roller and the position of the doctor blade.
A developing bias voltage generated by the high-voltage transformer PCB (HVTPCB) is applied to the developing roller
to provide image contrast.
1
Developing unit housing
2
Developing roller
3
Toner sensor (TNS)
4
Doctor blade
5
Right developing spiral
6
Left developing spiral
7
Developing paddle
Figure 2-1-14 Developing section block diagram
Figure 2-1-13 Forming a magnetic brush
A
A: Distance between the doctor blade and developing roller: 0.6
–0.05
mm
+0.1
4
7
6
5
3
1
2
N1
N1: 900
×
10
-4
±
50
×
10
-4
T
N2: 640
×
10
-4
±
50
×
10
-4
T
S1: 590
×
10
-4
±
50
×
10
-4
T
S2: 485
×
10
-4
±
50
×
10
-4
T
S3: 605
×
10
-4
±
50
×
10
-4
T
92
°
69.3
°
60
°
68.2
°
S2
S3
N2
S1
CN6-15
24 V DC
MPCB
CN1-1
DB
HVTPCB
CN6-10
DB REM
CN1-6
CN6-9
CN2-2
CN2-4
CN2-6, 7
DB CONT
TNS SIG
Developing roller
TNS CONT
CN1-7
TFM
