Dust Detection Preventive Process - Canon imageRUNNER 1750 Series Service Manual

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Technical Explanation > Original Exposure and Feed System > Controls > Dust Detection Preventive Process

■ Dust Detection Preventive Process

The contact image sensor (CIS) detects the reflected light from the ADF reading glass and
platen guide surface (at the read position) to judge presence or absence of dust.
This process is performed when the power is turned on or each time a job is completed.
The dust detection process is performed at three positions (A, B, and C) as follows regardless
of whether there is dust:
1) The dust detection process is performed at position A.
2) The dust detection position moves to position B to perform the dust detection process
there.
3) The dust detection position moves to position C to perform the dust detection process
there.
4-a) The dust-free position is determined as the original read position in the order of priority (A
> B > C).
4-b) If dust is detected at all of positions A, B, and C, position A is determined as the original
read position.
2 Technical Explanation > Original Exposure and Feed System > Controls > Dust Detection Preventive Process
0.5mm
A B C
ADF reading glass
Lens
Position
A Reference position for read
B About 0.5 mm to the right of the reference position A
C About 1.0 mm to the right of the reference position A
Note:
When dust has been detected at all of positions A, B, and C, setting an original on the
ADF will show a message that prompts the user to clean the glass surface.
2-17
0.5mm
Platen guide
Contact image sensor unit
F-2-28
Description
T-2-8
2-17