Patent ID: 8173950

Claim:
A reflective optical encoder, comprising: a substrate having a top surface; a light emitter mounted on or attached to the top surface and configured to emit light therefrom; a single track light detector mounted on or attached to the top surface, the single track light detector having a common axis, the single track light detector having disposed along the common axis a plurality of alternating sequences of pairs of A and B data channel light detectors and A/ and B/ data channel light detectors, and at least one pair of index channel I and I/ light detectors, wherein the A and A/ light detectors, and the B and B/ light detectors, are arranged 90 degrees out of phase with one another, and a code scale comprising index and data strips and configured to travel along the common axis, the code scale being located and configured operably in respect of the single track light detector such that at least a portion of the light emitted from the light emitter is reflected from the code scale towards the data and index channel light detectors; wherein each of the data channel light detectors has a first width and a first height, at least one of the index channel I light detector and the index channel I/ light detector has a second width greater than about 1.5 times, greater than about 2 times, or greater than about 3 times the first width, and at least one of the index channel I light detector and the index channel I/ light detector has a second height greater than the first height.