
EPSON EPL-N1600 Chapter 2 Operating Principles
Rev. A 48
XEROGRAPHIC MODULES
ROS ASSY: The ROS (Raster Output Scanner) Assembly
scans a laser beam on the drum surface. The
ROS Assembly consists of two major
components: PWBA LD and Scanner Assembly.
Basic Operation:
The Laser Diode (LD) of the PWBA LD emits
laser li
ht. The LD is switched on and off
accordin
to the print ima
e si
nal durin
printin
. The power of the laser li
ht is
monitored by the monitor circuit and controlled
to be a constant power. The laser li
ht from the
LD is shaped and conver
ed into a very thin
beam by means of a slit and a Cylinder Lens,
and directed to a Poly
on Mirror. The Poly
on
Mirror has six facets and is rotated at a constant
speed by the Scanner Motor. These facets
reflect the laser beam in turn as the Poly
on
Mirror rotates. The laser beam reflected by the
Poly
on Mirror passes throu
h a Correction
Lens L1 and is reflected by a Mirror M1 onto the
drum surface, movin
from one end of the Drum
to the other. The laser beam is thus scanned
one line by each facet of the Poly
on Mirror.
LD Output Power Control:
The drive current of the LD is switched on and
off by the Current Switchin
Circuit in the LDD
(Laser Diode Driver) accordin
to the print
ima
e si
nal (/PDATA) from the en
ine control
circuit. The LD drive current while the LD is on is
precisely determined by the two DC volta
e
si
nals (VLI and VL2) from HMCU. The laser
power is monitored usin
a monitor si
nal (MO),
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