Dirt Sensor Control; Dust Detection In Stream Reading Mode - Canon iR6570 series Service Manual

AB-Configuration
Original
size
A3
B4
A4R
A4
B5
B5R
A5
B6
none

5.3.5 Dirt Sensor Control

5.3.5.1 Dust Detection in Stream Reading Mode

The machine uses the dust detection control mechanism to check for dust on the platen glass and the ADF platen roller, thus preventing reproduction of
dust, if any, in output images.
Timing of Control
1. at the end of a job
2. between sheets (for every sheet)
*Executed only if dust has been detected at all points (A, B, C, D, E) during the previous job. In such a case, the machine will use the point subjected to
least dust, and executes correction before starting a read operation.
Particulars of Control
- At the End of a Job (changing the stream reading dust read position)
The machine measures the light reflected by the surface of the platen roller, and detects the presence/absence of dust with reference to its intensity. If
the presence of dust is detected, the machine moves to the next point (5 points max.; A -> B -> C -> D -> E).
The machine uses the first point at which the absence of dust is detected as the read point for the next job.
CCD point
of detection
Original
1 2 3 4
A B A B A B A B sensor 1
Start key
ON
1st
SCAN
Dust detection control*
Inch-configuration
CCD point
Original of detection
1
size
A B
11"x17"
LGL
LTRR
LTR
STMTR
STMT
absent
change absent
F-5-25
2nd
SCAN
Dust detection Dust detection control
control
F-5-26
Original
2 3
sensor 3
A B A B
:change present
Chapter 5
0008-7512
5-13