Toshiba 353 All in One Printer User Manual


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e-STUDIO350/352/353/450/452/453
LASER OPTICAL UNIT
8
8 - 5
© 2003 - 2008 TOSHIBA TEC CORPORATION All rights reserved
(3) f
θ
lenses-1 and -2
Thesetwolensesperformthefollowingadjustmentonthelaserbeamreectedbythepolygonal
mirror.
a. Uniform-velocity scanning
Since the polygonal mirror is rotating at a
uniformvelocity,thelaserbeamreected
from the mirror scans over the drum
surface at a uniform angular velocity;
namely, the pitch between the dots on
the drum is wider at both ends than at
the center of the scanning range. The
f
θ
lenses help to correct this difference,
making all the dot-to-dot pitches equal on
the drum surface.
b. Face tilt correction
Thereectingfaceofthepolygonalmir
-
ror is tilted slightly to one side against the
perfect vertical. Horizontal deviation of
the laser beam which is caused by the tilt
is corrected.
c. Sectional shape of laser beam
The shape of the laser beam spotted on
the drum is adjusted.
(4) H-Sync signal detection PC board
Thelaserbeamwhichisstartedtobescannedfromoneofthereectedplaneofthepolygonal
mirrorisreectedbytheH-SyncdetectionmirrorandentersthePINdiodeontheH-Syncsignal
detectionPCboard.Theprimaryscanningsynchronizingsignalisgeneratedbasedonthisreec-
tion.
Fig. 8-203
Fig. 8-204
Wider
Narrower
Drum
f
Ø
Lens-1
f
Ø
Lens-2
Same intervals
Mirror plane is tilted. Deviation
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