Epson LQ-2550 Technical Manual page 140

REV.-A
PF Motor Drive Circuit
Figure 2-86 shows the PF motor drive circuit and Figure 2-87 shows the PF motor drive circuit signal -"
timing. This circuit employs unipolar stepper motor driver IC STK698 1 H (7D) and drives the PF motor
using constant current chopper type control. The chopper type control is performed by a self-excitation
system using the reactance in the PF motor coil. The +35 V power supply voltage is applied
intermittently to the PF motor coil from
motor coil to keep the PF motor coil current constant.
Refer to Appendix A.1.l.l 1 for details of the STK6981 H.
+35 +
\ 16 16
D 0 2
14 1 4
B02
15
7
C 0 2
13
5
A 0 2
8
GH
and
AC
COM
PF MOTOR
1
POT3
Figure 2-86. PF Motor Drive Circuit
2-94
that a mean voltage is applied to the PF
+5
: D15
1
C34
17
SURGE VOLTAGE A8SORVING
12
GH
S w
C C
IR UIT
1
+35
=
ZD5