Patent ID: 9714846
Date: 2017-07-25
CPC Classifications: G01D

Claim:
1. A linear measurement system, comprising: a scale comprising a first plurality of scale bars extending along a measurement axis for a coarse position measurement and a fine position measurement; a scale bar energizer configured to energize the scale bars; a reader comprising a second plurality, less than the first plurality, of reader bars extending along the measurement axis; the reader moveable relative to the scale along the measurement axis whereby each of said reader bars is capacitively coupled to different ones of said scale bars; a controller responsive to a plurality of capacitively coupled signals from said reader bars resulting from a capacitive coupling of the reader bars to a plurality of the first plurality of scale bars for generating the coarse position measurement, the fine position measurement, and a measured position based on the coarse and fine measurements; the energizer is configured to provide the plurality of scale bars with a plurality of scale signals such that the plurality of capacitively coupled signals read by the reader are a unique set of signals for each position of the reader relative to the scale when in a coarse position measurement mode; and, a display for displaying the measured position.