Toshiba e-STUDIO281c Service Manual page 187

2) Polygonal motor unit
This unit consists of the polygonal motor (M4), polygonal mirror and polygonal mirror cover.
a. Polygonal motor (M4)
This motor rotates the polygonal mirror in high
speed.
The DC motor controls the rotation speed of
the mirror motor as follows:
During ready: 10,000.00 rpm
During printing
: 36,734.37 rpm (600dpi)
: 37,322.12 rpm (FAX 15.4x16.0dot/mm)
: 35,922.54 rpm (FAX 16.0x15.4dot/mm)
b. Polygonal mirror
One laser beam emitted from the laser diode
is reflected by this mirror. As the polygonal
mirror is rotated by the polygonal motor (M4),
the reflected laser light moves in sync with the
rotation. The direction of the movement is the
primary scanning direction of the image. One
scan is performed on one plane of the polygo-
nal mirror.
As the polygonal mirror has eight planes, eight
scans are performed in one rotation of the
polygonal mirror.
c. Polygonal mirror cover
Polygonal mirror cover reduces the windage
loss and noise, prevents adhesion of foreign
matters onto the mirror surface and releases
heat.
© 2005 - 2008 TOSHIBA TEC CORPORATION All rights reserved
( A )
( B )
( C )
Fig. 8-4
One scan is completed by completion of steps (A)
to (C). One scan is performed on one plane of the
polygonalmirror. Eight scans can be made with
one rotation of the polygonal mirror.
8 - 5
Drum
Laser beam
Drum
Laser beam
Drum
Laser beam
e-STUDIO281c/351c/451c
LASER OPTICAL UNIT
8