Oki ML490 Maintenance Manual page 23

(1) Space Motor Control
The SP motor driver (MHM2025) drives the three-phase brushless motor based on the
phase signal (SPU, SPV and SPW) from the LSI and the speed instruction data from the
MPU. The MPU can identify the current speed of the space motor by measuring through
the LSI the pulse length of the output (øA, øB) of the slit encoder included in the space
motor.
By comparing the target speed for each print mode with the actual current speed to change
the speed instruction data, the motor speed is accelerated or decelerated to maintain the
specified speed for each print mode.
SPU
SPV
SPW
42114101 Rev.1
SP truth table
HALL AMP INPUT
SPU SPV SPW
H H L
H L L
H L H
L L H
L H H
L H L
OUTPUT
U V W
OPEN L H
L OPEN H
L H OPEN
OPEN H L
H OPEN L
H L OPEN
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