Tray Paper Surface Detection - Canon Finisher-AB1 Service Manual

Chapter 3

3.3.4 Tray Paper Surface Detection

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.
UN15
[1]
[2]
UN17
[1]
[3]
[1]Paper
[2]Tray A
[3]Tray B
[4]Non-sort delivery roller
UN15:tray A paper surface sensor (light-emitting)
UN16:tray A paper surface sensor (light-receiving)
3-8
[4]
UN16
[5]
UN18
F-3-8
[5]Stack delivery roller
[6]Tray descent movement (sample)
UN17:tray B paper surface sensor (light-emitting)
UN18:tray B paper surface sensor (light-receiving)
[6]
UN16
[1]
[2]
UN16
[1]
[2]
0015-2075
3
2
1
3
2
1