Ricoh FT5034 Service Manual page 31

2. Light Shading Mechanism
The machine is designed so that the
intensity of the light across the drum is
uniform at 100% reproduction. However,
the intensity of the light striking the drum
tends to increase toward the edges when
the reproduction ratio is decreased, as a
result of the change in position of the lens.
For this reason, a light shading mechanism
has been installed to prevent uneven
illumination when making reduced copies.
When the lens moves in the reduction
direction, the groove cams move the
shading plates closer together.
The plates block part of the light passing
through the lens to keep the intensity of the
light on the drum even.
3. 2nd Scanner Drive
In order to provide the proper optical
distance between the original and the lens,
this model uses a stepper motor to move
the second scanner.
A separate motor is used because the
second scanner must travel a long distance
in order to accommodate a wide range of
reproduction ratios.
When the second scanner motor drives the
second scanner drive pulley, the wire
pulleys rotate as shown by the black
arrows ( ).
So, the second scanner moves in the
direction of the white arrow (
ð
).
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Shading Plate
Groove Cam
2nd Scanner
Drive Pulley
Shading
Cam Plate
2nd Scanner
2nd Scanner
Pulley