Spacing Operation - Oki ML390 Service Manual

Page: 23
Service Guide ML390/391
Chapter 2 Principles of Operation

2.3.04 Spacing Operation

Spacing Motor Control
The motor control LSI produces the spacing motor phase signals SP-U, SP-V, SP-W and the overdrive
signal SPD-A in accordance with spacing commands from the microprocessor.
The SPD-A signal is a fixed period pulse signal whose pulsewidth is controlled by the program. This signal
is used to control motor drive time.
The signal SP ON/OFF is used at acceleration/deceleration, when a large amount torque is required.
The motor driver (MTDV) drives the space motor in accordance with the SPD-A and SP ON/OFF signals.
Pins 9 and 11 of the MTDV are the protection circuits against over voltage and over current.
Spacing Motor Encoder Disk / Photosensor
As the spacing motor is driven, the signals PHASE-A and PHASE-B are generated by the photosensor /
encoder disk (which is mounted to the spacing motor).
The motor control LSI divides the frequency of these signals in accordance with the selected print pitch.
The LSI generates the IPT-N signal, which provides dot-on timing and carriage position detection.