Ricoh Aficio Color 6010, Руководство по обслуживанию

Страница: 102 / 448

LASER EXPOSURE 30 March, 1999
2-58
f
θθθθ
Lenses and the BTL
The angles between pixels are equal.
However, if the beam were to go directly
to the drum as shown in the upper
illustration, the spacing between pixels
would depend on the angle of the beam.
The pixels near the end of the drum
would be further apart than the ones
near the middle, and slightly thicker
toward the ends of the drum than in the
middle.
The f-theta lenses [A] and barrel toroidal
lens (BTL) [B] correct for this by
deflecting the beam slightly inward to
ensure uniform pixel spacing and
diameter. The f-theta lenses and BTL
also correct for very slight deviations of
the polygon mirror surfaces from being
perfectly perpendicular to the plane of
the laser beam.
Laser Synchronization Mechanism
The laser synchronizing detector board
[A] synchronizes the main scan start
timing. This board generates and sends
a synchronization signal when the laser
synchronizing detector mirror [B] reflects
the laser beam to the detector as the
laser beam starts its sweep across the
drum.
A269D098.WMF
A269D101.WMF
[A]
[A]
[B]
[B]