Brother HL-1660e Series User Manual page 20

2. LASER/SCANNER SYSTEM
To external device
Main PCB
SBD DATA VOFF
Scanner driver
Collimator lens
Scanning mirror
Cylindrical lens
Scanner motor
Optical sensor
Focusing lenses
Beam detect mirror
Figure 2.4
In response to the print signal transmitted from the external device, the main PCB generates the
drive signals (DATA,VOFF) for the laser diode and sends the signals to the scanner unit.
The laser diode in the scanner unit generates a laser beam modulated by DATA.
The modulated laser beam is aligned into a parallel beam by a collimator lens and a cylindrical
lens and then brought to the scanning mirror which is rotating at a constant speed.
The laser beam reflected by the scanning mirror focuses on the photosensitive drum via the
focusing lenses arranged in front of the scanning mirror.
The path of the beam coming through the focusing lenses is reflected by the reflective mirror.
As the scanning mirror rotates at a constant speed, the laser beam scans the photosensitive
drum at a constant speed.
As the photosensitive drum rotates at a constant speed and the laser beam scans the drum, an
images is formed on the drum.
II - 4