Canon ImageRunner iR8500 Series, Service Manual, Page: 277 / 1122

Chapter 5
5-25
T-5-16
5.3.5 Dirt Sensor Control
5.3.5.1 Detecting Dust in Stream Reading
0006-9651
iR105i/iR105+ / iR9070
In addition to the common points for stream reading, the machine uses an additional 6 points each for small-size and large-size sheets at intervals of 0.5
mm to avoid areas of dust (in total, 7 points for small-size and 7 points for large-size).
If it detects dust, however, it changes the point of reading to prevent dust from appearing in images. The detection of dust is executed at the end of each
single job that uses stream reading; the machine moves the ADF belt idly when stream reading is selected and identifies any black line as an area of dust.
When it detects dust, it resets the current point of stream reading, and uses the point of reference on the leftmost edge for dust detection; if dust is detected,
it moves the point of stream reading to the right by 1 point (0.5 mm) for detection of dust for a second time. If dust is not detected, the machine uses that
point as the point for stream reading. If dust is detected once again, it will use the next point. If dust is detected at all 7 points, the machine will indicate
the message "Copyboard Glass Soiled," which will remain unit the ADF is opened and the copyboard glass is cleaned. The machine will not use stream
reading but use fixed reading as long as the message remains.
F-5-46
Advise the user to clean the area where the CCD stops in stream reading if the message has appeared. A label indicating the points for stream reading (for
small-size and large-size) is attached to the rear of the copyboard glass.
If a jam has occurred, the machine will not execute dust detection at the end of a job. If the ongoing job is cancelled, it will execute dust detection at the
end of operation.
AB-Configuration Inch-Configuration
Originals
Point of CCD detection
Original Originals Point of CCD
detection Original
size 1 2 3 4 sensor size 1 2 sensor
A3 yes yes yes yes yes 11"x 7" yes yes yes
B4 yes yes yes no yes LGL yes no yes
A4R yes yes no no yes LTRR yes no no
A4 yes yes yes yes no LTR yes yes no
B5 yes yes yes no no None no no no
B5R yes no no no yes
None no no no no no yes: Changes no: Does not changes
Black line on
output
Dust
3 mm (7 points)