Laser Exposure - Ricoh FAX2900L Service Manual

PRINTING

2.2.4 LASER EXPOSURE

Overview
[C]
[A]
[B]
• The focusing lens [A] is a double toroidal lens that has a barrel toroidal
surface on both sides.
• The shield glass [B] prevents toner and dust from entering the laser optics
area.
• Mirror motor [C] speed: 10086.2069 rpm (16 dots/mm)
• The strength of the beam emitted from the LD unit [D] is 4 mW with a
wavelength of 780 nm. The photo transistor [E] inside the LD unit
synchronizes the laser main scan.
• The mirror [F] reflects the laser beam onto the drum.
The charge on the exposed areas of the drum drops to about -200V while non-
exposed areas remain at around -750V.
As a mechanical safety feature, a shutter slides to block the laser beam path
whenever the upper unit is opened.
Cross Reference
Group 3 Facsimile Manual: section 4-3-3
H547D505.WMF
2-8
21 May, 1999
[E]
[D]
[F]