Canon Color Image Reader - L1 Service Manual page 24

2
Technology
Stream reading glass dust detection control
The machine checks the presence/absent of dust on the stream reading glass and the DADF
platen roller 1. It then changes the point of reading or executes image correction (refer to
[dust detection correction control (continuous lines)]) depending on the result of detection to
avoid the reproduction of dust particles in its output images.
a. At the start of a job
The scanner unit moves to the reading position saved at the detection of the previous job
ends.
After it moves, the dust detection is executed. If the dust is detected, the machine executes
dust correction by making correction on the pixels on both sides of the area where dust is
found.
[1] It moves to the reading position.
b. Between sheets
The dust detection is executed. If the dust is detected, the machine executes dust correction
by making correction on the pixels on both sides of the area where dust is found.
The scanner unit does not move due to the dust detection.
c. At the end of a job
1) The scanner unit moves to the default reading position A.
[2] It moves to the reading position A.
*1: In case that the reading position at the start of a job is one other than A.
2) The dust detection is executed. If there is no dust on the A position, the machine saves
the A as a reading position for a next job and fi nishes the dust detection.
3) If there is a dust on the A position, the machine execute the dust detection on the B
position. If there is no dust on the B position, the machine saves the B as a reading
position for a next job and fi nishes the dust detection.
[3] It moves to the B position.
4) If there is a dust on the B position, the machine executes the dust detection on the C
position. If there also is a dust on the C position, the machine saves the position where
the least dust is found among the A, B or C positions as a reading position for a next job
and then, displays an alarm to perform the cleaning.
[4] It moves to the reading position C.
2
Technology
0.5 mm 0.5 mm
A B
At the start
of a job
[1]
At the end
of a job
[2]
*1
[3] [4]
MEMO:
(Lv.1) COPIER > OPTION > IMG-RDR > DFDST-L1
Adjustment of the dust detection level between sheets
(Lv.1) COPIER > OPTION > IMG-RDR > DFDST-L2
Adjustment of the dust detection level at job end
C
*1
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