Ricoh FT7770 Service Manual page 77

To center the image on the copy paper, the lens also moves to the side (per-
pendicular to the direction of paper movement) when the reproduction ratio
A bearing on the bottom of the lens housing is engaged with
is changed.
one of the grooves on the lens cam plate.
guide rod X, the lens cam plate forces the lens housing to move along guide
rod Y.
When the lens moves to the left-front side for reduction copying, the light
striking the lens becomes nonsymmetrical. (The halogen lamps are positioned
to provide symmetrical light when the lens is at the home position.) To
prevent this from causing uneven exposure, a shutter plate is positioned in
front of the lens. This shutter blocks part of the light and makes the light
intensity even.
The shutter plate is mounted on the lens housing. A pin on the bottom of
the shutter engages a groove on the lens cam plate, and the shutter moves
sideways as the lens moves along guide rod X.
u
As the housing moves along
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April, '89