Epson AcuLaser C2800 - Ros Assy

AcuLaser C2800/C2800D/C3800/C3800D Revision C
OPERATING PRINCIPLES Main Structures and Functions 49
Confidential
2.5.5 ROS ASSY
2.5.5.1 Part Names and Functions
 ROS ASSY
ROS ASSY (Raster Output Scanner Assembly) is the exposure unit that outputs a
laser beam to make a electrostatic latent image on the drum surface.
In this manual, items concerning the ROS ASSY are simply called “ROS”.
The ROS ASSY mainly consists of the components shown below.
 LD PWB
LD PWB consists of four Laser Diodes (LD) that correspond with Y, M, C,
and K. LDs convert image data input as electrical signal into flashing of a
laser beam. PWBA LD monitors the laser beam at all times so that the amount
of laser beam that draws latent image remains stable. This control is called
“APC” (Auto Power Control).

Scanner Assy
Scanner Assy consists of a Scanner Motor that rotates at constant speed and a
Polygon Mirror attached to the rotary shaft of the motor.
Laser beam emitted from LD irradiates the Polygon Mirror via a mirror.
Polygon Mirror has a six-sided reflecting mirror, and the Scanner Motor
rotation changes an angle of reflection. This allows the laser to scan across on
the drum from side to side. The laser can scan one horizontal line on the drum
while it hits on the reflecting mirror.
 Mirror/Window/Lens
Laser beam reflected by Polygon Mirror irradiates the drum surface via Lens,
Mirror, and Window. Lens is for correcting aberration, Mirror is for ensuring
an optical path, and Window keeps foreign materials from entering inside
ROS.
 SOS PWB
SOS Sensor on SOS (Start of Scan) PWB converts input laser beam into
electrical signal as a start of scanning.
This signal is used to match the start timing of a laser scanning with that of
image drawing.
Figure 2-25. ROS Assy
 LD PWB
LD (Laser Diode)
 Scanner Assy
Polygon Mirror
 SOS PWB
SOS Sensor
 Lens
 Mirror  Window