Canon Paper Deck-V1, Service Manual

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Chapter 2
2-11
2.4 Deck Lifter
2.4.1 Detecting the Presence/Absence of Paper
0009-2054
The lifter of the deck is joined to a reel by means of a cable, and is driven by the deck lifter motor (M102); i.e., the
lifter moves up or down depending on the direction of rotation of the motor.
When the deck (compartment) is pushed inside the host machine, the deck open detecting switch (SW101) is pushed.
The lifter starts to move up as soon as the deck open sensor (PS109) detects the light-blocking plate; the lifter stops
to move up when the deck position sensor (PS104) detects the top of the stack of paper placed on the lifter
In the rare event that the lifter should fail to stop moving up after the sensor lever blocks the deck lifter position sensor
for some reason, the deck lifter upper limit sensor (PS103) will go on to stop the lifter, thereby preventing damage
to the deck.
The lifter, on the other hand, starts to move down when the deck open switch (SW100) is pushed, and will keep
moving down until the lifter moves past the sensor lever of the deck paper supply position sensor (PS107), i.e., falling
edge of the sensor output.
The addition of paper in this condition will push the lever of the deck paper supply position sensor, causing the lifter
to move farther down until the stack of paper moves past the sensor lever.
The lifter repeats its descent operation each time paper is added until the deck lifter lower limit detecting switch
(SW102) is pushed (maximum paper supply position).