Detecting The Size Of Originals - Canon imageRUNNER 2525 Series Service Manual

■ 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 Change in Horizontal Scan Direction
In the horizontal scan direction, magnification is changed as follows depending on the selected magnification rate:
1. When magnification is reduced to 50-99%
• In the Book mode
Data is processed on the main controller PCB with the original scan speed held at 61.5 mm/sec or 123 mm/sec.
• When the ADF is used
The original feed speed is changed within the range of 61.5 mm/sec or 123 mm/sec to 246 mm/sec depending on the
selected magnification rate. Data is not processed on the main controller PCB.
2. When magnification is increased to 100-200%
The original scan speed (in the Book mode)/original feed speed (when the ADF is used) is changed within the range of 123
mm/sec to 61.5 mm/sec depending on the selected magnification rate. Data is not processed on the main controller PCB.

■ Detecting the Size of Originals

● Overview
The original size is identified by the combination of presence and absence of output levels of the reflection type sensors as
summarized in the tables below.
• Absence of paper: The light reflected from the reflection type sensor changes when the copyboard cover is open/close.
• Presence of paper: The light reflected from the reflection type sensor does not change when the copyboard cover is open/
close.
This machine is provided with the following sensors. Locations of the sensors are shown below.
• Vertical scan direction: Reflection type photo sensors (2 locations for AB; 1 location for Inch)
• Horizontal scan direction: Reflection type photo sensors (2 locations for AB; 2 locations for Inch)
CMOS sesor channel x 4
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2. Technical Explanation