Canon iR3245, Service Manual

Page: 171 / 746

Chapter 5
5-15
5) Standby status (waiting for start key)
CCD unit: in original detection position
LED: OFF
Original sensor: OFF
F-5-20
F-5-21
5.3.5 Dirt Sensor Control
5.3.5.1 Overview
0019-4650
iR3225 / iR3225N / iR3235 / iR3235N / iR3245 / iR3245N
The machine changes the original read point or executes image correction depending on the presence/absence of dust on the stream reading glass or the platen roller
of the ADF to prevent the dust from showing up in the output. These operations are carried out only when the ADF is in use and, in addition, is closed.
[Control timing]
- At the end of a job
- Between sheets (for each reading of a sheet)
- At the start of a job (only when any of the following conditions is true.)
First job after power-on
Dust detected at all points of detection at the end of the previous job
Dust detection failed to end normally at the end of the previous job (e.g., ADF opened)
F-5-22
[Particulars of control]
- At the end of a job (dust detection)
CCD checks the light reflected by the surface of the platen roller of the ADF at the read point to detect the presence/absence of dust. Presence of dust is detected
at points A, B, and C in this order. The point where least dust is detected will be used as the read position for the next job.
The point selected here will be used as the read position for the next job.
Regarding the control at the end of a job, if an original is placed in the ADF with dust detected at all points (A, B, C), the machine will indicate a message on its
control panel to prompt cleaning of the glass surface. The Start key will remain invalid until this message is cleared.
Original
size
A3
B4
A4R
A4
B5
B5R
A5
B6
Absent
Original
sensor 0
CCD detection position
ABtype
11"×17"
LGL
LTRR
LTR
STMTR
STMT
Inch type
No change Changed
1
A B
2
A B
3
A B
4
A B
1
A B
2
A B
3
A B
Original
size Original
sensor 1
CCD detection position
Absent
Main power
switch
ON
Dust detection
control
STBY WMUP
Start key
ON
1st
SCAN 2nd
SCAN
Dust detection
control
Dust detection
control