Patent ID: 7091884
Filing Date: 2006-08-15
Classification: G01D,H03M

Abstract:
1. A position-measuring circuit for use with an analog position encoder comprising a code member and at least one sensor for sensing successive marks on the code member during relative movement between the code member and sensor and providing an oscillating signal in response thereto, the position-measuring circuit comprising means for obtaining a relatively coarse measure of position by detecting successive distinguishable instants in the signal, means for establishing relatively high and low threshold levels based upon the amplitudes of the signal at least at selected detection instants, wherein a value of the high and low threshold levels vary with the sensor position and/or over time, and are set to change dynamically with an amplitude of the signal during operation of the analog position encoder, and means for obtaining a fine measure of position by measuring an instantaneous amplitude of the signal and calculating the fine measure as a function of the instantaneous amplitude of the signal and the difference between neighboring high and low threshold levels.