Dual Beam Writing - Ricoh B079 Service Manual

6.6.3 DUAL BEAM WRITING

This LD unit employs two laser diodes
[A] (LD) and [B] (L2). Each face of the
polygon mirror writes two main scan
lines, and twelve main scans are
produced when the polygon mirror
rotates once. This reduces polygon
motor rotation speed, reduces noise
generated by the polygon motor, and
reduces the frequency of the image data
clock.
The two laser beams follow the path:
collimating lenses [C] " prism [D] "
polygonal mirror [E]
The two laser beams arrive on the drum surface about 2 mm apart in the main
scan direction and about 0.06 mm apart (at 400 dpi) in the sub scan direction (see
the next page). The two-mm difference in the main scan direction allows the
machine to detect the laser synchronization signal for each beam.
SM
CÓPIA NÃO CONTROLADA
[B]
[A]
2 mm
P1: 400 dpi
P2: 600 dpi
6-49
CÓPIA NÃO CONTROLADA
LASER EXPOSURE
[C]
[D]
B004D203.WMF
B079/B082
[E]