Canon F1 Service Manual page 36

2
Technology > Controls > Reader > Original size detection
3) Close DADF (The angle of DADF is from 5 to 25 degree).
3-1) The external light detection operation is performed. Since the area covered by an
original will be blocked from external light, the machine will assume the absence of an
original at points that detect external light. After the DADF sensor 2 detects [Close],
the external light detection operation is started.
In case of the described original size, A3/B4/A4/B5 are excluded from the list of
possible sizes at this point.
25 degrees
original
: external light
3-2) After the external light detection operation, the machine turns ON the LED in the
main scanning direction and the reflected light is detected by the reading sensor
(5 points). After the first detection, it continues detection by the specified interval (it
completes after 3 sec). The original size sensor 1 starts detection in the sub scanning
direction.
25 degrees
: LED light
2 Technology > Controls > Reader > Original size detection
4) DADF fully closed (the angle of DADF is 5 degree or less).
The machine monitors the changes of output level of each sensor for 3 sec from when
the DADF open sensor 1 detects the [Close] status. The machine determines the original
presence in the point where the output level has no change.
The machine identifies the original size from the combination of the level change at 5 points
(priority on the front original presence).
5) Wait status (wait for start key)
Scanner unit: Stream reading position
F-2-48
LED lamp unit: ON
Original size sensor: OFF
F-2-49
5 degrees
2-23
F-2-50
F-2-51
2-23