Absolute encoder utilizing a code pattern carrier having a varying mixture of phosphors deposited thereon

摘要

An encoder having a code carrier, light source, and detector is disclosed. The code carrier includes a track that emits light at each of a plurality of track points on the track when that track point is illuminated with light having a predetermined spectrum. Each of the track points emits light having a spectrum that is different from the spectrum emitted by others of the track points. The light source illuminates a portion of the track with light of the predetermined illumination spectrum. The detector provides a plurality of signals indicative of the spectrum of light leaving the portion of the track when the portion includes one of the track points. The code carrier moves with respect to the detector, and the signals define the relative position of the code carrier with respect to the detector.