Canon PC770 Service Manual - Page 56

Current, switching, circuit, Motor, driver, COPYRIGHT, CANONINC., CANON PC7207401150IT10,

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=OPERATIONS AND TIMING 4. Driving the Scanner Motor a. Outline The scanner motor (M2) is a 4-phase stepping motor. It is turned on or off and its direction and speed of rotation is changed by controlling the output timing of the drive power supply SC-COMA and SC-COMB and pulse signals A, A*, B, and B*. b. Operation The microprocessor (Q101) on the DC controller PCB receives such instructions as copying modes and reproduction ratios from the control panel circuit; and, in response, it sends drive pulses to the scanner motor (M2) through the motor drive circuit. The scanner motor is a 4-phase stepping motor, and controls the direction and speed of scanning by changing the frequency and the sequence of drive pulses (SC-A through SC-B*). The motor drive voltage on/off switching circuit supplies power to drive the motor and removes power to stop it. The current switching circuit sets the current flowing to the motor according to the speed of rotation; the motor driver circuit is used to control the rated current according to the setting. (Q101) DC controller PCB Voltage on/off signal 24V Motor drive voltage on/off switching circuit J101 SC-COMA I SC-COMB A A* Microprocessor B B* (Q109) 5V Current switching signal ► Current switching circuit Motor driver circuit SC-A SC-A* Q.9 SC-B SC-B` g M2 Figure 3-207 3 - 16 COPYRIGHT © 1994 CANONINC. CANON PC7207401150IT10REV.0 AUG.1994 PRINTEDINJAPAN(mput AU JAPAN)

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=OPERATIONS
AND
TIMING
4.
Driving
the
Scanner
Motor
a.
Outline
The
scanner
motor
(M2)
is
a
4
-phase
stepping
motor.
It
is
turned
on
or
off
and
its
direction
and
speed
of
rotation
is
changed
by
controlling
the
output
timing
of
the
drive
power
supply
SC
-COMA
and
SC
-COMB
and
pulse
signals
A,
A*,
B,
and
B*.
b.
Operation
The
microprocessor
(Q101)
on
the
DC
controller
PCB
receives
such
instructions
as
copying
modes
and
reproduction
ratios
from
the
control
panel
circuit;
and,
in
response,
it
sends
drive
pulses
to
the
scanner
motor
(M2)
through
the
motor
drive
circuit.
(Q101)
Microprocessor
DC
controller
PCB
24V
Voltage
on/off
signal
The
scanner
motor
is
a
4
-phase
step-
ping
motor,
and
controls
the
direction
and
speed
of
scanning
by
changing
the
frequen-
cy
and
the
sequence
of
drive
pulses
(SC
-A
through
SC
-B*).
The
motor
drive
voltage
on/off
switching
circuit
supplies
power
to
drive
the
motor
and
removes
power
to
stop
it.
The
current
switching
circuit
sets
the
current
flowing
to
the
motor
according
to
the
speed
of
rotation;
the
motor
driver
circuit
is
used
to
control
the
rated
current
according
to
the
setting.
A
Motor
drive
voltage
on/off
switching
circuit
J101
SC
-COMA
I
SC
-COMB
A
*
B
B
*
Current
switching
signal
►
Current
switching
circuit
5V
(Q109)
Motor
driver
circuit
SC
-A
SC
-A*
SC
-B
SC
-B`
g
Figure
3-207
Q.9
M2
3
-
16
COPYRIGHT
©
1994 CANONINC.
CANON PC7207401150IT10
REV.0
AUG.1994
PRINTED IN JAPAN
(mput
AU JAPAN)