Rice Lake Okidata 320-390-420 Turbo - Service Guide - Manual (Page 21)

Page: 9
Service Guide ML320/321Turbo
Chapter 2 Operation Description
2.1.6 SP/LF Motor Control
(1) Space motor control
The SP motor driver (HA13412) drives the three-phase brushless motor 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 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 increased or decreased to maintain the specified speed for each print
mode.
(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.