Scanning System - Brother HL-3450CN Service Manual

1.5

Scanning System

This printer employs a semiconductor laser diode as a light source. This laser diode is
switched according to the transmitted image data (video signal).
The generated laser light scans over the OPC belt through a polygon mirror and lens, by
which method electrostatic latent images will be formed on the OPC belt.
(1) Structure of the Scanning System (Refer to Fig.4-24.)
The scanner unit is located as shown in Fig.4-8.
The scanner unit consists of the following parts;
c
d
e
f
g
h
i
j
k
Scanner Unit box
Dust proof glass
Developer belt
Scanner Unit: Light emitting source incorporating a laser diode.
Cylinder lens: Condenser for the laser beam.
Polygon mirror: Hexahedral mirror for scanning the laser beam.
6
Focus lens for the laser beam.
F- lens:
Scanner motor: Motor to rotate the polygon mirror.
Mirror: Reflecting mirror for the laser beam path.
LDC: Laser diode control circuit.
PD: Beam detector.
BTD mirror: Beam timing detector mirror to guide the laser beam
to the PD sensor.
6
4
2
5
3
Fig. 4-24
4-23
HL-3450CN SERVICE MANUAL
8
9
2
1
7