Patent ID: 8217808
Filing Date: 2012-07-10
Classification: G01D

Abstract:
1. An incremental coder comprising: a movable element and a fixed element, two sensors secured to the fixed element, a succession of marks secured to the movable element that can be detected by the sensors during the motion of the movable element with respect to the fixed element, means of binary coding representing the detection and the absence of detection of the marks by the sensors, the coding arising from one sensor being phase-shifted with respect to the coding of the other sensor, a change of binary value of one of the codings defining an interval of the coder, the codings forming a binary word, stable positions of the coder being defined by multiples of the coder interval, and means for defining a value of variation of stable positions of the coder on the basis of the binary word, the coder further comprising a memory containing a number of intervals between two stable positions, wherein the means for defining a current stable position of the coder compute a difference between a binary word obtained for a current stable position and a binary word obtained for a previous stable position, and compute the value of variation of stable positions by determining the integer part of the division of the difference by the number of intervals between two stable positions.