Canon Color Image Reader - L1 Service Manual page 26

2
Technology
Dust detection correction control (non-continuous lines)
The machine detects and corrects the lines due to the dust other than dust between sheets.
The dust on the original is not detected before the leading edge of original. This dust some-
times stops at the reading position due to the friction with the reading glass and sticks to the
original again. In this case, the dust is fed together with the original and will not be detected
after the trailing edge of the original. This control detects the non-continuous lines appears
between the leading edge and the training edge formed as above and corrects the image.
This correction targets the lines in the sub scanning direction on the read image. The ma-
chine determines whether the lines are due to the dust or not by the length, color and bright-
ness of lines and the correction is executed if the lines are deemed as dust-related lines.
Also, if the dust causing lines exceeds the specifi ed amount, the machine displays an alarm
to prompt cleaning.
Before reading
Platen roller 1
Original
Floating dust Stream reading
Scanning position
2
Technology
After reading
glass
MEMO:Additional function mode (removing the faulty lines)
At the original reading, you can specify whether to execute the removing function or not
when non-continuous lines are detected.
Setting items are as below.
•
ON: Detect and remove the non-continuous lines (default).
•
OFF: Do not remove the non-continuous lines.
When there are extra-fi ne lines on the original, if this item is set to ON, the machine
sometimes detects them as non-continuous lines erroneously and they may be re-
moved from the image. If the extra-fi ne lines on the original are removed frequently due
to wrong detection, specify this item to OFF.
Result of reading
It sticks on the original
during scanning.
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