Epson EPL-N4000, Service Manual

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EPSON EPL-N4000/EPL-N4000+ Chapter 2 Operating Principles
Rev.B 64
2.3 ROS (Raster Output Scanner)
The ROS (Raster Output Scanner) is the mechanism that carries out
Step 2. Expose of the print cycle.
Figure 2-18. Exposure
A semiconductor within the ROS Assembly generates a beam of laser
light. Image data received from the print controller modulates this beam,
turning it on and off according to image information that is received from
the host computer. Through the use of a series of rotating and
stationary mirrors within the ROS, the beam sweeps the negative
charged drum surface. Whenever the print controller sends a command
to print a black pixel, the laser switches on long enough to shine onto
the drum at a single pixel point. That point on the drum is now
discharged.
Figure 2-19. Laser Beam
2.3.1 ROS Components
The ROS Assembly is made up of one major component housing a
number of sub-components.
2.3.1.1 Housed inside the ROS Assembly
Laser Diode Assembly (LD)
A semiconductor Laser Diode that generates a 5 milliwatt class 3B
laser beam. Circuity on the LD PWB maintains the laser output
power at a constant level. The LD PWB is electrically connected to
the MCU PWB and to the C262 Main Board. The MCU provides
power and control circuitry. C262 Main Board provides the video
data input from the host computer
Corrective Lenses and Angled Mirror
Four lenses, two small, one medium, and one wide, and an angled
mirror focus the laser beam and direct it toward the Polygon Mirror.
Polygon Mirror
A twelve-side rotating mirror that is attached to the Scanner Motor
Assembly. The movement of the rotating Polygon Mirror reflects the
laser beam in a sweeping motion, from side to side across and
through the wide lens.
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sr1321x
W A R N I N G
The ROS generates a laser beam. The laser beam is
a very powerful and narrow beam of light that
produces extreme heat at its focal point. The laser
beam in this printer is invisible.
Although you cannot see the beam, it can still
cause severe eye injury. Direct eye exposure to the
laser beam may cause blindness. Never place a
mirror or a reflective tool or object in the laser beam
path. Never run the printer with the covers removed
or the ROS interlocks bypassed.