Toshiba e-STUDIO453 Service Manual page 160

(2) Polygonal motor unit
This unit consists of the polygonal motor, polygonal mirror and polygonal mirror cover.
a. Polygonal motor
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: 38,090.55 rpm (600dpi)
: 38,951.37 rpm (FAX 15.4 × 16.0 dot/mm)
: 37,490.70 rpm (FAX 16.0 × 15.4 dot/mm)
b. Polygonal mirror
8
One laser beam emitted from the laser
diode is reflected by this mirror. As the
polygonal mirror is rotated by the po-
lygonal motor, the reflected laser beam
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
polygonal 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 wind-
age loss and noise, prevents adhesion
of foreign objects onto the mirror surface
and releases heat.
e-STUDIO350/352/353/450/452/453
LASER OPTICAL UNIT
( A )
( B )
( C )
Fig. 8-202
One scan is completed by completion of steps (A) to (C).
One scan is performed on one plane of the polygonal-
mirror. Eight scans can be made with one rotation of
the polygonal mirror.
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Drum
Laser beam
Drum
Laser beam
Drum
Laser beam