Exposure Stage - Brother HL-1070 - B/W Laser Printer Service Manual

2.5.2

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
+1000
+700
+400
+300
Drum
Sleeve
Drum
Paper
Laser beam
f
lens
Polygon mirror
Motor
Lens
Fig. 2.28
reduced forming the electrostatic image to be printed.
1 Cycle of drum
1 2 3
(a)
(b)
Fig. 2.29
Laser Beam
Primary charging
1
4
2
Laser beam exposure and developing
(a) Unexposed area
(b) Exposed area
3 Transfer the image to paper
Erase the residual potential
4
Time
II-22
( Non image area )
( Image area )