Ricoh FT5233 Service Manual page 54

12 February 1992
4. OPTICS
4.1 OVERVIEW
[D]
[E]
During the copy cycle, an image of the original is reflected onto the drum
surface via the optics assembly as follows.
Light Path:
Exposure Lamp [A] →
→ 2nd Mirror [D] →
→ 4th Mirror [G]
→ Toner Shield Glass [J] → OPC Drum [K]
The optics cooling fan [L] removes warm air (heated by the exposure lamp)
from the optics cavity. This blower operates if the optics thermister installed
on the left scale bracket senses 40°C or more. This operation reduces the
possibility of the optics unit becoming dirty by the optics cooling fan.
The 1st scanner (lamp and 1st mirror), 2nd scanner (2nd and 3rd mirrors),
3rd scanner (4th and 5th mirrors), and the lens function together to achieve a
wide range of reproduction ratios (50 –200%).
The auto density selection (ADS) sensor board is mounted on the optics
bottom plate in the lens housing cover. The ADS sensor board collects light
reflected from the original in ADS mode. Original length and width sensors
are mounted in the optics cavity for the original size detection.
A thermoswitch (turning off at 130°C) is installed on the back of the exposure
lamp reflector as a back-up safety for preventing the optics unit overheating.
[B] [A]
[I]
[C]
[K]
Original [B]
3rd Mirror [E]
→
5th Mirror [H]
2-25
[F]
→
1st Mirror [C]
→
Lens [F]
→
6th Mirror [I]
OPTICS
[G] [L]
[J]
[H]
→
→
→