Canon imageRUNNER ADVANCE C3330 Series Service Manual page 46

Related Error Codes
• E302-0001 : White Shading error
• E302-0002 : Black Shading error
Related Alarm Codes
• 02-0025 : Insufficient Scanner Unit LED light intensity alarm
● Dust detection / correction control
Overview
Dust detection / correction control executes the following processing in association with the shading correction to correct image
density variation (white streaks) in areas of dust.
1. Before shading, dust adhered at shading positions is detected.
2. After shading, the shading coefficient of already detected areas of dust is corrected.
Execution timing
Dust detection / correction control is always executed at the time of white shading during shading correction.
There are 2 processings for dust.
Processing to avoid dust (when starting the first stream reading job after turning ON the power, when ending a stream
reading job, etc.)
Like the time of completion of a job, presence/absence of dust is detected at all positions (1, 2, 3, 4 and 5 in that order). The
position where dust is least present is used as the reading position and reading starts.
Processing to correct dust (when a regular stream reading job starts, between papers)
Dust detection is executed at the reading position, and image density variation (white streaks) in areas of dust is corrected
from the next original if there is any dust.
0.5 mm 0.5 mm
2 3 1 4 5
1
2
3
4
5
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2. Technology