Canon imageRUNNER ADVANCE 4551i Service Manual page 60

■ Dust Detection Control
● Overview
When reading an original, original reading position is changed according to the presence/absence of dust on the Stream Reading
Glass or the Guide Plate of the ADF (on the Platen Roller in case of the reverse model), or image correction is performed to
prevent the dust to be printed on an image. This control is performed only when the ADF is being used and has been closed.
[Control timing]
• At job completion
• At paper interval (after each sheet is read)
• At the start of a job (only when one of the following conditions is met)
When dust is detected at all detection points when the previous job finished
When dust detection was not completed normally when the previous job finished (because the ADF was opened, etc.)
Main power
switch ON
AB type
Original detection
position 1
Original detection
position 2
Original detection
position 3
Original detection
position 4
Original detection position 5
Original detection position 6
CCD original detection position
Inch type
Original detection
position 1
Original detection
position 2
Original detection
position 3
CCD original detection position
Start key
ON
WMUP STBY
Dust detection
Original sensor 1
A5R
B5R
A5 A4R
B5
K16
A4
STMTR
LTRR
STMT
LTR
1st 2nd
SCAN SCAN
Dust detection
control
control
47
2. Technology
B4
K8
A3
Original sensor 2
LGL
279.4×431.8mm
(11"×17")
Dust detection
control