Canon DR-2580C Service Manual page 33

3. Shading
This section describes how the reading
unit (lower) mechanically works when a
shading correction value is determined.
The reading unit is usually set up so that
the background color becomes black. When a
shading correction value is determined, the
data on a shading plate need to be read. Thus,
the reading unit (lower) is moved about 2 mm
to the document pickup side.
Figure 2-204 describes the structural
drawing of that part. If the carry motor is ro-
tated opposite to the feed direction, the me-
chanical clutch which is installed on the shaft
of the eject roller 1 rotates. At this point in time,
the coupling plate starts rotating by the head of
the coil spring and the reading unit moves
horizontally.
When such motor normally rotates, the
reading unit returns again to its original posi-
tion.
COPYRIGHT © 2005 CANON ELECTRONICS INC.
Eject roller 1
Reading unit (lower)
CANON DR-2580C FIRST EDITION APR. 2005
CHAPTER 2 FUNCTION & OPERATION
Shading plate
Mechanical clutch
Coupling plate
Pickup side
Figure 2-204
Reading unit (upper)
Shading plate
Reading unit (lower)
Figure 2-203
Carry motor
2-7