Oki ML420 Maintenance Manual page 24

(2) Encoder disk
In the operation of the spacing motor, the PHASE-A and PHASE-B signals are generated
when the encoder disk interrupts the photo sensor.
The LSI divides these edge pulse signals in accordance with the print pitch, and sends
the IPT signal to provide dot-on timing and carriage position detection timing.
SPU
SPV
SPW
PHASE-A
PHASE-B
• UTILITY MODE
IPT 10 CPI
IPT 12 CPI
IPT 15 CPI
IPT 17 CPI
IPT 20 CPI
(3) LF motor control
The LF motor driver (MHM2025) drives the LF motor in two-phase or 1-2 phase bipolar,
based on the phase changeover data and the output current data from the MPU.
The data from the MPU is processed by a specific register contained in the LF motor driver
to measure the overdrive time and to change the phase.
PHASE-A
PHASE-B
42113901TH01 Rev.3
1/720"
1/120"
1/144"
1/180"
1/206"
1/240"
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