EPSON AcuLaser CX11/CX11F Revision B
OPERATING PRINCIPLES Printer Section Operating Principle 109
2.2.5.1 Main Functions
ROS ASSY
 ROS ASSY
ROS ASSY (Raster Output Scanner Assembly) is the exposure unit that outputs
the laser beam to make the electrostatic latent image on the drum surface. (From
here on, ROS ASSY is simply called "ROS.")
ROS consists of the components shown in Figure 2-45.
îš„ The PWBA LD (Laser Diode) converts the image data (electric signal), to
laser light ON/OFF signals.
PWBA LD constantly monitors the laser light intensity so that laser intensity
stabilizes to the appropriate level when making the electrostatic latent image.
This is called " APC (Automatic Power Control".
îš„ The Scanner Assy consists of a Scanner Motor that operates at a fixed speed
and a polygon mirror attached to the Motor's rotary shaft.
The laser beam emitted from the PWDA LD is irradiated on the polygon
mirror.
The polygon mirror has six reflecting mirror surfaces, and the angle of the
reflected laser beam changes by rotation of the Scanner Motor. This lets the
laser beam scan across on the Drum from side to side. The laser beam makes a
single line on the Drum with one reflective mirror.
îš„ The laser beam reflected by the polygon mirror passes through the lens,
mirror and window to reach the drum surface. The lens functions to
compensate for aberration, the mirror to ensure an optical path, and the
window to prevent the entry of foreign bodies into ROS.
îš„ The timing to start writing image data must synchronize exactly with the
beginning of laser scanning in order to properly form an electrostatic latent
image on the drum surface. When the SOS sensor on the PWBA SOS (Start
Of Scan) receives the laser beam, it converts the laser into an electric signal
(SOS signal) for detecting the initial position (start of scan reference point) for
scanning the various lines.
Figure 2-45. Main Functional Components of ROS
Leg_Sec06_008FA
Drum
Mirror
Lens COL
Lens CYL
Lens L1
Polygon Mirror
PWBA SOS
SOS Sensor
Scanner Assy
PWBA LD
Mirror SOS
Window
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