b. Detecting the Volume of Copy Paper
The volume of remaining copy paper is
checked by three sensors (Q43, Q45, Q18), and
the result is indicated on the control panel in
terms of three levels or the Add Paper message.
q
From when the lifter starts to move up until the
sensor arm blocks the Q43, the result indi-
cates that the volume of paper on the side tray
is 1/2 or more.
w
From when the lifter moves farther up until the
sensor arm blocks Q43, the result indicates
that the volume of paper on the side tray is
between 1/2 and 1/4.
e
From when the lifter moves even farther until
the sensor arm blocks Q45, the result indi-
cates that the volume of paper on the side tray
is 1/4.
Table 3-403
When copy paper runs out and the sensor arm
blocks Q18, the Add Paper will be indicated. At
such times, the lifter keeps moving until the cam
presses the upper limit detecting switch (SW10).
The lifter, on the other hand, keeps moving
down until its cam presses the lower limit detect-
ing switch (SW11).
At power-on, the lifter moves to the level sen-
sor (Q45, Q43) or the lifter lower limit detecting
switch (SW11) to find out the current position.
c. Paper Deck Motor Control Circuit
The paper deck motor control circuit is located
on the side tray controller PCB. (See Figure 3-405
for its block diagram.)
The combination circuit in Figure 3-405 con-
sists of various logic circuits, and it generates the
up/down switching signal and the paper deck
motor ON signal (=0) based on the output signals
and control signals from the various sensors and
switches.
The two signals are used to operate the motor
drive circuit to drive the paper deck motor clock-
wise or counterclockwise.
If an overcurrent flows because of a short cir-
cuit in the motor, the overcurrent detection circuit
forces OFF the paper deck motor ON signal. If the
circuit has activated, remove the cause, and turn
OFF and ON the power switch to reset.
■
Conditions to Move Up the Lifter
•
The paper deck is closed so that
➝
The door open signal (STDO) is ‘0’.
•
The light-blocking plate is not at the lifter
position sensor, and the lifter upper limit
switch is OFF so that
➝
The lifter position signal (SLTP) is ‘0’.
•
The output of the microprocessor (Q115)
on the DC controller PCB (lifter ON control
signal) is ‘0’.
•
The output of the microprocessor (Q115)
on the DC controller (lifter up/down control
signal) is ‘0’.
As the result of the above, the combination cir-
cuit generates the following outputs:
up/down switching signal=0 and
paper deck motor ON signal=0,
thereby moving up the lifter.
3. OPERATIONS AND TIMING
COPYRIGHT © 1996 CANON INC.
CANON NP6085 REV.0 JULY 1996 PRINTED IN JAPAN (IMPRIME AU JAPON)
3-87
1/2 ~ 1/4
1/4 or less
1/2 or more
Indication
Sensor No.
Q43
Q45
Q18
OFF
ON
ON
ON
No paper
OFF
OFF
ON
ON
OFF
OFF
OFF
ON
