公开(公告)号：US20230251114A1

公开(公告)日：2023-08-10

申请号：US17668290

申请日：2022-02-09

Applicant: Apple Inc.

Inventor： David D. Dashevsky ,  Christopher Gardiner ,  Tingjun Xu

IPC: G01D13/04

CPC classification number: G01D13/04

Abstract: A method includes imaging, with an optical read head attached to a second mechanical component, a portion of an encoder track disposed on a first mechanical component. The encoder track has a first encoder scale extending along the encoder track and a second encoder scale extending along the encoder track, and the imaged portion of the encoder track includes a first portion of the first encoder scale and a second portion of the second encoder scale. The method further includes transforming an imaged portion of the encoder track to a spatial frequency domain; identifying a pair of frequency bins in the spatial frequency domain; determining a phase difference between a first frequency bin and a second frequency bin in the pair of frequency bins; and mapping the phase difference to a positional relationship between the first mechanical component and the second mechanical component.