Dirt Sensor Control; Overview - Canon Color iR C3480 Service Manual

After the copyboard cover sensor has identified a "closed" state, the machine checks for a change in the output level of the original sensor (CCD point of
detection) for 3 sec. If there is no change in the level of output, the machine identifies the condition to indicate the presence of an original.
The machine uses combinations of changes in the levels of 6 locations to identify the size of the original:
6) Standby (in wait for a press on the Start key)
CIS: moves to home position
xenon lamp: off
original sensor: off
AB-Configuration
Original
size
A3
A4
B4
B5
A4R
A5
B5R
No original

5.3.6 Dirt Sensor Control

5.3.6.1 Overview

Color iR C3380G / Color iR C2880G / Color iR C3380i / Color iR C3380 / Color iR C2880i / Color iR C2880 / iR C3480 / iR C3480i / iR C3080 / iR C3080i / iR
C2550
When reading an original, the machine changes the point of reading or corrects image data in reference to the presence/absence of dust on the stream reading glass/
ADF platen roller, thereby avoiding the effects of dust on images. The machine executes this control only when the ADF is used and, in addition, when it is closed.
1. Timing of Control
(1) at the end of a job
(2) between sheets (each time a sheet is read)
(3) at the start of a job (only if any of the following is met)
(a) first job after power-on
(b) presence of dust at all points of detection at the end of the previous job
(c) failure of dust detection at the end of the previous job (e.g., the ADF is opened)
Original
1 2 3 4 sensor1
Main power
Start key
switch
ON
ON
WMUPR STBY
Dust detection control
Original sensor
Original(A4R)
1
2
3
4
Original size detection position
F-5-23
Copyboard glass
CIS HP
F-5-24
Inch-Configuration
Original
size
1
11"X17"
LTR
LGL
LTR-R
STMT-R
No original
F-5-25
1st 2nd
SCAN SCAN
Dust detection control
Dust detection control
F-5-26
Original
2 3 sensor2
: Change absent
: Change present
Chapter 5
0013-8592
5-15