Brother mfc8440 - Exposure Stage

MFC-8440/8840D/8840DN, DCP-8040/8045D/8045DN
SERVICE MANUAL
3-23
2.7.2 Exposure stage
After the drum is positively charged, it is exposed to the light emitted from the laser unit.
Fig. 3-36
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.
Fig. 3-37
Drum
Lens
Laser beam
Polygon mirror
Paper
Laser detecto
r
Laser diode
Motor
Laser beam
f θ lens
3
Primary charging
Laser beam exposure and developing
(a) Unexposed area
(Non image area)
(b) Exposed area
(Image area)
Transfer the image to paper
Time
Drum
sleeve
0
2 1
1
2
3
(a)
(b)
+150
+400
+870
Surface
potential (V)
1 Cycle of drum