Oki OKIFAX4550, Maintenance Manual

Page: 321 / 592

41309401TH Rev.4
321 /
M
CN13
1
2
3
4
DM-T1
DM-T2
DM-T3
DM-T4
(2 phase excitation)
Drum motor
46F
Drum motor
drive
IC9
IOGA4
DMPH1
DMPH2
DMON1-N
IC2
Figure A.13 (1/2) Related Signals of Drum Motor
3.8 46F Circuit Diagram (8/13)
1. Block diagram
46F-PCB circuit diagram (8/13) shown the consists of the following functions and connectors:
• IC9 (Drum motor driver)
• Connector CN13 that provides an interface between 46F board and the drum motor.
Figure A.13 shows the related signals of the drum motor.
2. Function
1)
Drum motor control
This drum motor is driven by the motor driver IC9. It is two-phase excited and bipolar-driven
according to the DMPH1, DMPH2 and DMON1-N signals that are generated from the
IOGA4 (CPU). This drum motor rotates the image drum.
2) Drum motor timing chart
Figure A.13 (2/2) Drum motor signal timing chart
T0
DMPH1-P
DMPH2-P
Operation at normal speed: T0 to T3 = 0.781 ms
T1 T2 T3
3) Drive control
Time T0 to T3 determines the motor speed, while the difference of phase direction between
phase signals DMPH1-P and DMPH2-P determines the rotation direction, DMON1-N
signals control a motor coil current. According to the polarity of the phase signal, the coil
current flow as follows:
1) +38V
→
SW
→
motor coil
→
SW
→
resistor
→
earth, or,
2) +38
→
SW
→
motor coil
→
SW resistor
→
earth
The voltage drop across the resistor is input to comparator, where it is compared with a
reference voltage. If an overcurrent flow occurs, a limiter operates to maintain it within a
certain fixed amount of current.