Canon iR4570 Series Service Manual page 229

-Between Sheets
The machine does not move the contact image sensor (CIS) for dust detection between sheets. It reads the original
using the position determined at the end or start of a job; if the presence of dust is detected, however, the machine
will execute image correction.
0.5mm 0.5mm
A B C
ADF
reading
glass
F-5-24
<Service Mode>
COPIER>OPTION>BODY>DFDST-L1 (level 1)
(used to adjust the dust detection level between sheets)
COPIER>OPTION>BODY>DFDST-L2 (level 1)
(used to adjust the dust detection level at the end of a job)
Point Discription
A read reference position
B about 0.5 mm from the reference position
to the inner side of the roller
C about 1.0 mm from the reference position
to the inner side of the roller
Platen roller
Lens
Contact image sensor
LED
T-5-7
Chapter 5
5-21