Canon Saddle Finisher-AF2, Service Manual

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Chapter 3
3-5
3.3.4 Tray Paper Surface Detection
0020-4695
The machine is equipped with a mechanism to detect the position of the top of the stack deposited in its 2 trays.
The trays are each fitted with a sensor PCB that consists of a light-emitting segment (UN15, UN17) and a light-receiving segment (UN16, UN18).
The light-emitting segment is arranged at the rear of the machine, and is a LED. The light-receiving segment, on the other hand, is found at the front of the machine,
and it consists of 3 photosensors.
When the power is turned on or a jam has been removed, the finisher controller PCB checks the 3 photosensors (light-receiving segment) as soon as the LED (light-
emitting segment) goes on.
As more and more sheets are deposited in the tray, the light reaching the light-receiving segments will be blocked, causing the finisher controller PCB to move
down the tray to keep the top of the stack at a specific level.
When the tray becomes full of paper (i.e., light blocked, not reaching any of the 3 photosensors), the finisher controller PCB switches over to a different tray for
subsequent delivery. If the newly selected tray is full, it will stop the operation of the machine, and will indicate the fact to the host machine.
F-3-8
[1] Auxiliary tray solenoid drive signal
SL9: Auxiliary tray solenoid
M23: Tray lift motor
MEMO:
A stack with a folded sheet tends to be higher along its lead edge than its trail edge, blocking the discharge slot when it contains multiple folded sheets. (A subsequent
sheet will likely hit the preceding sheet, causing a jam.)
[1] Paper [5] Stack delivery roller
[2] Tray A [6] Tray descent movement (sample)
[3] Tray B
[4] Non-sort delivery roller
UN15: Tray A paper surface sensor (light-emitting) UN17: Tray B paper surface sensor (light-emitting)
UN16: Tray A paper surface sensor (light-receiving) UN18: Tray B paper surface sensor (light-receiving)
[1]
[1]
[2]
[3]
[4]
[5]
UN15
UN16
UN16
UN17
UN18
1
2
3
UN16
1
2
3
[1]
[2]
[1]
[2]
[6]