Laser Exposure; Overview - Ricoh FAX3700l Service Manual

August 2nd,1995

2.2.4. Laser Exposure

1. Overview

[F]
[A]
The components of the laser section are the same as those described in the
section 4-3-3 of the Group 3 Facsimile manual. The drum [A] is positioned in
the same plane as the laser unit, so there is no mirror to change the optical
path.
Points to note:
•
The focusing lens [B] is a barrel toroidal lens.
•
The shield glass [C] prevents toner and dust from entering the laser op-
tics area.
•
An optical fiber [D] passes the reflected laser beam to the laser sychroni-
zation detector circuit in the FDU.
•
The shape of the mirror [E] is hexagonal.
•
The strength of the beam emitted from the LD unit [F] is 5 mW at a
wavelength of 780 nm.
The dimensions of the dot on the drum are 85 µm by 85 µm.
•
The hexagonal mirror motor speed depends on the printing resolution:
•
Copy and G3 l/mm mode (16 x 15.4 dots/mm): 10402 rpm
•
Printer mode (300 dpi):
The charge on the exposed section of the drum drops to about -100 V while
non-exposed areas it remains at about -750 V.
Cross reference
Group 3 Facsimile Manual: section 4-3-3
DETAILED SECTION DESCRIPTIONS
7977.8 rpm
2-15
PRINTING
[E]
[D]
[B]
[C]
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