Identifying The Size Of The Original - Canon DADF-M1 Service Manual

Chapter 2

2.3.3 Identifying the Size of the Original

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A. Normal Printing
The machine identifies the size of an original with reference to combinations of the size
(width, length) detected on the original tray and the size (length) detected while the original
is being moved.
a. Detecting the Size of the Original in Feed Direction
The machine detects the size of an original in feed direction with reference to the state of
the post-separation sensor (PI7) after the read sensor (PI8) has gone off and the state of the
LGL sensor (PI4)on the tray (LGL/STMT).
The machine measures the length of the time from when the read sensor goes on to when it
goes off to find out the length of the original; it then uses the result of the measurement and
the result of detection made on the original tray to identify the size of the original.
ADF driver PCB
Trailing edge of the original
(small size)
PI7
PI8
Trailing edge of the original
Read standing by position
(large size)
F-2-18
When an original is placed on the original tray, the light-blocking plate operates in keeping
with the detecting lever of the LGL sensor to block the light of the photo interrupter. The
machine identifies whether or not the original is LGL with reference to the LGL sensor
signal (LG_S) and the width of the original. The machine communicates the original size
information to the host machine as soon as the Start key is pressed.
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