Sharp FO-4500, Руководство по обслуживанию

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(9) Driver block
Sending motor driver (IC13, IC17: PBL3717/2) ---- 16-pin DIP
This IC drives at the sending motor at the constant current with the
bipolar, chopper system.
•
Operation description (Refer to the waveforms of the terminal volt-
age and current waveforms.
1
The current M in the coiling of the motor is converted in the cur-
rent-voltage mode with the resistors RS (R2, 3, 5 and 6) which are
connected the terminal E (pin 16), is farther transmitted to the C
terminal (pin 10) through the filter Cc (C15, 16) and Rc (R4, 7).
(Vc)
2
The reference voltage (VR’) and (Vc) voltage of each comparator
are compared with the comparator which is selected with I
0
(pin 9)
and I
1
(pin 7).
3
If Vc
≥
VR’ is established here, the signal is output to the monost-
able to turn off the lower side of the bridge type output transistor
only for the time (0.69CrRr) determined by CT (C30, 31) and RT
(R10, 11) which are connected to the terminal T (pin 2) in order to
shut down the coil current IM.
4
At this time, the counter-electromotive force is generated by the
winding inductance. However, the energy is reduced with dis-
charge through V
MM
and the diode between M
A
and M
B
.
5
When the time (0.69CrRr) determined with the monostable has
passed, the transistor on the lower side is turned on again to flow
the winding current I
M
. Being suppressed by the inductance of the
motor, the current will increase and return to
1
.
3
15
8
6
1
7
9
11
–
+
–
+
–
+
5
4
12
13
10 2 16
SCHMIT1
TRIGGER
PHASE
VCC
CURRENT SENSOR
LOGIC I1
INPUT IO
&
GND
C
OUTPUT STAGE
1
MA
VMM
MONOSTABLE
IOR=0.69•PrCr
14
1
1
TIME
DELAY
MB
1
>
=
1
>
=
VR
& & &
T
E
Fig. 3
VCX
0V
VE (Pin16)
VC (Pin10)
T0
VF
V sat rec
V sat cond
T ON
TD
T OFF
(–0.69 RtCt)
V sat
t
IMP
IMX
0A
IM (MOTOR CURRENT)
t
t
VS
VS
0V
0V
VMA (Pin15)
VMB (Pin1)
VM - VMB - VMA
t
VCX
0V
t
Fig. 4
FO-4500H
5 – 15