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Service Guide ML520/521
Chapter 2 Principles of Operation
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.
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