Ricoh FT 4015, Service Manual

Page: 20 / 229

3. OPTICS
3.1 OVERVIEW
During the copy cycle, an image of the original is reflected onto the drum
surface through the optics assembly as follows:
Light path:
Exposure Lamp [A]
→
Original
→
First Mirror [B]
→
Second Mirror [C]
→
Third Mirror [D]
→
Lens [E]
→
Blue Filter [F]
→
Fourth Mirror [G]
→
Fifth
Mirror [H]
→
Sixth Mirror [I]
→
Drum [J]
This copier has eight standard reproduction ratios and a zoom function. The
operator can also change the reproduction ratio in one-percent steps from
50% to 200%. Stepper motors are used to change the positions of the lens
and 4th/5th mirrors to enlarge/reduce the image across the page. Changes in
reproduction ratio down the page are achieved by changing the scanner
speed.
The CPU monitors the temperature around the optics through a thermistor
which is located on the scanner frame. When the temperature reaches 40
°
C,
the optics cooling fan [K] starts rotating to draw cool air into the optics cavity.
The fan operates until the temperature drops below 38
°
C.
Additionally, a thermofuse on the 1st scanner provides back-up overheat
protection. It opens when the temperature reaches 128
°
C and cuts ac power
to the exposure lamp.
A blue filter is located just after the lens to improve the reproduction of red
areas of the original on copies.
[C] [C] [A] [B] [K] [E] [I] [G]
[H]
[J]
[D]
[F]
A219D507.wmf
OPTICS 20 December 1996
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