Oki Microline 520

Space Motor Control
The SP/LF motor driver
(Location 5A: MHM2025)
drives the three-phase brushless
motor. Motor movement is
based on the phase signal
(SPU,SPV and SPW) and the
speed instruction data from the
LSI. The MPU can identify the
current speed of the space motor
by measuring the pulse width of
the output (Phase A, Phase B)
of the encoder disk sensor.
After comparing the target speed
for each print mode with the actual
speed, the motor is accelerated or
decelerated to maintain the desired
speed for each print mode.
Encoder Disk
As the space motor operates, the
encoder disk spins. When the
encoder disk interrupts the photo
sensors, the signals Phase A and
Phase B are generated. The LSI
(Location 04B: MSM79V035)
divides these edge pulse signals
(the frequency division is based
on the selected print pitch) to
generate the signal IPT. The IPT
signal provides dot-on timing
and carriage position detection
timing.
2-1-05b.tif
2-1-05c.tif
Microline 520/521 Service Handbook 2 - 11 Principles of Operation
P/N 59257803