Ricoh FT 4015 Service Manual page 20

OPTICS
3. OPTICS
3.1 OVERVIEW
[C] [C] [B] [A]
[D]
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.
[K] [E] [F] [I]
[J]
2-6
20 December 1996
[G]
[H]
A219D507.wmf