Laser Unit - Xerox Phaser 6121MFP Service Manual

Theory of Operation

Laser Unit

Imaging Unit Exposure
2-20
The Laser Unit in the Phaser 6121 printer has two laser diodes. The laser diode
control circuitry adjusts the light intensity for each beam automatically. Image
data is transmitted to the laser diodes in the Laser Assembly as digital signals. The
laser diodes convert the image data from digital signals to optical signals. The
Laser Assembly monitors and adjusts the intensity of the laser beams to attain a
stable electrostatic image. The Laser Assembly is replaced as a complete assembly.
Functional components within the Laser appear in the following.
SOS Mirror
G2 Lens
G1 Lens
Polygon Mirror
Semiconductor Laser
The surface of the Imaging Unit is irradiated with laser light to form an
electrostatic latent image. The polygon mirror has four faces. The two-beam laser
array consists of two laser diodes arranged vertically. Two lines are scanned
through a single face of the polygon mirror.
Laser Diode
Polygon Mirror
Return Mirror
Photo Conductor Surface
Beam A
Beam B
Photo
Conductor
G2 Lens
G1 Lens
Return Mirror
Phaser 6121MFP Service Manual
SOS Sensor
s6121mfp-117
s6121mfp-118