Enlargement/Reduction; Detecting The Size Of Originals - Canon imageRUNNER 2545 Series Service Manual

2
Technology > Original Exposure System > Controls > Detecting the Size of Originals

■ Enlargement/Reduction

● Magnifications in Main Scanning Direction
In book mode/ADF mode
An image is read at 100% in main scanning direction. Magnification variation and its data
process are controlled on main controller PCB.
● Magnification in Sub Scanning Direction
To vary the magnification of sub scanning direction, the machine operates as below
depending on the original reading methods and the magnifications.
1) Magnifications in book mode
To suite the selected rate of magnification, the machine changes the speed of original
reading and executes data processing on main controller
PCB.
e.g.) Reduction to 25%: an original is read at 249.5mm/s, and the data is processed for 25%
reduction (skipping for 4/1) by the main controller PCB.
e.g.) at 100%: an original is read at 249.5mm/s.
Operation
Speed change of original reading (mm/
sec)
Digital magnification process (%) on the
main controller PCB
2) Magnifications in ADF mode
To suite the selected rate of magnification, the machine changes the speed of original
reading and executes data processing on main controller
PCB.
e.g.) Reduction to 25%: an original is read at 249.5mm/s and the data is processed for 25%
reduction (skipping 4/1) by the main controller PCB.
e.g.) Enlargement to 200%: an original is read at 124.7mm/s and the data is processed for
100% direct reproduction by main controller PCB.
Operation
Speed change of original reading (mm/
sec)
Digital magnification process (%) on the
main controller PCB
2 Technology > Original Exposure System > Controls > Detecting the Size of Originals
Magnifications
25% to 50% 50.1% to 199.9% 200% to 400%
249.5 249.5 124.7
25 to 50 50.1 to 199.9 100 to 200
Magnifications
25% to 50% 50.1% to 199.9% 200% to 400%
249.5 249.5 124.7
25 to 50 50.1 to 199.9 100 to 200

■ Detecting the Size of Originals

● Overview
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.
● Control Details
T-2-5
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.
AB type
Original sensor 0
Original detection
position 1
B6
Original detection
position 2 A5
Original detection
position 3 B5
Original detection
position 4 A4
T-2-6
CCD original detection position
Inch type
Original detection
position 1
STMTR
B5R
Original detection
position 2
A4R
STMT
B4
Original detection
position 3
A3
LTR
CCD original detection position
2-9
Original sensor 1
LTRR LGL
279.4×431.8mm
(11"×17")
F-2-14
2-9