Operating Principles
LC&300
Service Manual
2.3.8 Paper Feed Motor Driver Circuit
Figure 2-19 shows the paper feed motor driver circuit, an open-loop, constant-voltage drive with
1-2 phase excitation.
The ports (pins 7-lo) on the CPU are used to control the stepping motor. The pulse signal from the
IC1
controls four
tmmsistors
and the stepping motor. The motor is driven at six speeds, 300,500,
600, 1000, 1200, and 1300 pps, to correspond to the idling voltage, the paper handling condition,
and the volume of paper feeding.
The
CPU controls motor driving speed. At the holding time, the
PFCOM
voltage is changed VX
(+35
V) into VL (+5 V) via
Q1
and
Q6 by the gate array.
Gate Array
143
I
CPU (ICI)
E
M13
M12
Mll
MIO
PF Motor Drive
Transistors
Q2
==%
!37
PF-~
!W
Q3
PF_A
139
Q4
PF~
140
Q5
P FA
+5V
A4
&
k---wTpFcOM
~-
‘
1
J
VL
Vx
Figure 2-19. Paper Feed Motor Driver Circuit Diagram
2.3.9
Printhead Driver Circuit
Figure 2-20 shows the
printhead
driver
circuit block diagram. Print data, already expanded into
image
data
is split by the
CPU
and transferred to the
latch
circuit in the gate array in the system.
Port
AN6
(pin 66) of
IC1
samples
the
voltage of the +35
VDC
line
via the A/D converter. By
sampling the +35
VDC
line voltage and deterrninin
g the length of the head drive signal, it is
possible to maintain the energy supplied to
the
head at a constant level. If the voltage from the
+35 V line is HIGH,
ICI
shortens
the
output
puke.
If the voltage from
the
+35
VDC
line is LOW,
ICI lengthens the output pulse.
CPU
DATA
BUS
ANI
62
Gate Array
VP
QM1 -6
●
,
●
●
●
●
●
●
y
9
●
-vW-
●
● :
●
●
●
+
!
●
●
●
●
b
,
●
+5
v
VP
Id
A=
-1-
d
Figure 2-20.
Printhead
Driver Circuit Diagram
#l
#24
c
.,
\
.,
.
c
.,
.,
f
‘
--h
i
,-,,
2-16
Rev.A
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