Brother MFC-P2000 - B/W Laser Printer Service Manual page 38

2) Exposure Stage
After the drum is positively charged, it is exposed to the light emitted from the laser unit.
Laser detector
Laser diode
The area exposed to the laser beam is the image to be printed. The surface potential of
the exposed area is reduced, forming the electrostatic image to be printed.
+1150
+700
+400
+300
Drum
Sleeve
Drum
Paper
Laser beam
f
lens
Polygon mirror
Motor
Lens
Fig. 2-27
1 Cycle of drum
1 2 3 4
(a)
(b)
Time
Fig. 2-28
Laser Beam
Primary charging
1
2 Laser beam exposure and developing
(a) Unexposed area
( Non image area )
(b) Exposed area
( Image area )
3
Transfer the image to paper
Erase the residual potential
4
II-19