Patent ID: 8760153

Claim:
A rotary encoder, comprising: a magnet disposed on a rotational axis of the encoder, the magnet polarized transversely to the rotational axis; a first magnetic sensor disposed on the rotational axis proximate the magnet disposed on the rotational axis; a magnet ring disposed rotationally coaxially with the rotational axis and having a selected diametric distance from the rotational axis, the magnet ring having a plurality of alternatingly polarized magnets, a number of pole pairs in the magnet ring resulting from the alternatingly polarized magnets selected to match an angular resolution of the first magnetic sensor; and a second magnetic sensor disposed proximate a flat surface of the magnet ring, the second magnetic sensor having a selected angular resolution, whereby a combination of signals from the first magnetic sensor and the second magnetic sensor comprises an angular resolution of the first magnetic sensor divided by the angular resolution of the second magnetic sensor and an absolute angular orientation, the angular resolution of each of the first and second magnetic sensors defined, respectively as a number of sensor counts per revolution of the magnet disposed on the rotational axis and the magnet ring.