Toshiba 4560, Руководство по обслуживанию

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Nov. 1997 © TOSHIBA 18 - 55 4560/4570 RADF
The figure above shows the equalizing circuit of the STK6713BMK4. The circuit comprises a phase
driver, comparator, PWM excitation selector and current detection resistor.
When a L-level signal is input to
φ
A and a H-level signal is input to
φ
A
–
, Q1 turns ON. As the + terminal of
IC1 (comparator) becomes L-level, the output S of IC1 becomes L-level. As current iON of the A coil
passing through Q1 increases, the voltage across the terminals of source resistor R7 also increases,
output
S
becomes H-level from the moment that the voltage across pin 8 and R
02
becomes equal, and
Q1 is turned OFF.
The energy accumulated at coil L1 of the pulse motor is induced to L2. At this time, the current flowing to
L2 is taken as i
OFF
. The energizing time of i
OFF
is the time up to when the voltage accumulated at capaci-
tors C1 at both ends of R3 becomes equal to the voltage across both terminals of R
02
. When the voltage
is equal, output
S
is inverted, and becomes L-level, so motor coil current i
ON
increases to the voltage
level of R02 again. In this way, the motor current is turned ON/OFF, that is, current chopping operation is
repeatedly carried out.
The same operation is carried out for other phases.
(Motor rotation amount input circuit)
This circuit is for improving stop positional accuracy by counting the number of steps of the pulse motor.
A pulse of cycle twice the step of the pulse motor is output from the output obtained by inputting PMA1
and PMB1 from amount the 2-phase excitation pulses to EXOR (IC13). When both edges of this pulse
are detected by the CPU interrupt terminal, the number of motor steps can be counted.
(Description of STK6713BMK4 Internal Circuit Operation)
-
+
F2
i
Q2
j i
Q1
j
F1
2
A
3
A
15
A
13
A
8
Td1
9
Vref
12
NC
1
Vcc2
+5V
Vcc1
S
IC2
IC2
IC2
IC2
R1
IC1
C1
R3
R5
D1
R7
F3
D2
R8
IC3
IC3
IC3
F4
IC3
R2
IC1
+
-
R4
R6
C2
B
4
PQ
6
B
7 16
B
Td2
14
B
10 11
Vref
5
SQ
ON OFF
1 1
L2
L1
R01 R02