Circuit Diagram (8/13) - Oki OKIFAX4550 Maintenance Manual

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.
IC2
DMPH1
DMPH2
IOGA4
DMON1-N
2) Drum motor timing chart
DMPH1-P
DMPH2-P
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.
41309401TH Rev.4
IC9
Drum motor
drive
(2 phase excitation)
Figure A.13 (1/2) Related Signals of Drum Motor
T0 T1
Figure A.13 (2/2) Drum motor signal timing chart
46F
CN13
DM-T1
1
DM-T2 2
DM-T3 3
DM-T4 4
T2 T3
Operation at normal speed: T0 to T3 = 0.781 ms
Drum motor
M
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