Canon iR3245, Service Manual

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Chapter 5
5-12
5.3.4 Detecting the Size of Originals
5.3.4.1 Overview
0019-4675
iR3225 / iR3225N / iR3235 / iR3235N / iR3245 / iR3245N
The machine identifies the original size by the combination of measurement result of reflection light from the reflection sensor and specific points of CCD. Also to
identify it accurately even though an original moves when ADF is closed, the machine measures 2 points for each size.
- Main scanning direction: CCD (AB type: 8 points measurement, inch type: 6 points measurement)
- Sub scanning direction: Reflection type photo sensor (AB type: 1 point, inch type: 1 point (original sensor 2 is not used.))
The followings are the procedures of original size identification.
1)External light search (main scanning direction only)
According to the LED status, the machine identifies the CCD level of each detection position in main scanning direction.
2)Output level detection of each sensor
The machine turns on the LED on CCD unit and measures the CCD level of each detection position in main scanning direction.
Also, turns on the LED on reflection type photo sensor in sub scanning direction and measures the sensor output.
The original size is identified by the combination of these output result.
5.3.4.2 Control Details
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iR3225 / iR3225N / iR3235 / iR3235N / iR3245 / iR3245N
For main scanning direction, the machine moves the CCD unit to the following CCD original detection positions according to the location of original to measure
the CCD level of each detection position. For sub scanning direction, the machine uses the original sensor 0, 1 to identify sizes.
F-5-12
1. 2 points original detection at each detection position
For each point of measurement in main scanning direction, the machine checks the presence/absence of an original with reference to the CCD output at 2 points
near the point of measurement.
* The machine checks if the signal is changed or not from ADF (pressure plate) open to close at both points of 1A and 1B.
Change in the signal: Yes
Change in the signal: No
Judgment is done by the measurement results of 1A and 1B, and it indicates the presence of original if either point shows absence (absence). It indicates absence
of original if both signals show Yes (presence).
F-5-13
T-5-3
Change Result of detection
1A 1B
Yes Yes Original absence
No Yes Original presence
Yes No Original presence
No No Original presence
Original sensor 0
Original detection
position 1
B5
B6
A5
A4
B5R
A4R
B4
A3
CCD original detection position
LTRR STMT
LTR
LGL
279.4×431.8mm
(11"×17")
AB type Inch type
STMTR
Original detection
position 2
Original detection
position 3
Original detection
position 4
CCD original detection position
Original detection
position 1
Original detection
position 2
Original detection
position 3
Original sensor 1
approx 4mm
approx 13mm
1A=additional
detection point 1
Borderline of
original size
1B=conventional
detection point 2
Borderline of
original size