HL-5130/5140/5150D/5170DN SERVICE MANUAL
3-29
2.6.2 Exposure
stage
After the drum is positively charged, it is exposed to the light emitted from the laser unit.
Fig. 3-45
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. 3-46
Drum
Lens
Laser beam
Polygon mirror
Paper
Laser detector
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
