Service manual

AR-651/810 SCANNING SECTION 6 - 5
6. 3. 2. Two-phase motor drive circuit (fixed-current type)
The scanner motor is driven by the unipolar transistors as shown below. The current chopper method is
employed by the driver circuit to improve motor torque STK672-080 (IC4).
15 14 13 12 11 10
9 8
6 7
ENABLE
Mol
RESET
M3
CLOCK
CWB
M2 M1
Vcc2 Vref A AB B BB
PG
SUB
5 4 3 2
1
Excitation mode setting
Switching pulse ON/OFF detection
Excitation status monitor
CR oscillation
Phase counter
Generation of reference clock
PWM control
Generation of phase excitation signal
Generation of pseudo sine wave
Switching current fraction ratio