ANGLE ENCODER

摘要

An angular position sensor comprising a body (1) rotatable about an axis of rotation (8) fixed with respect to a surrounding housing (5). The body having a grating element (2) comprising a surface of revolution about the axis of rotation. The surface comprising a pseudo-random distribution of regions of high (21) and low (22) EMR reflectivity arranged in the form of endless succession of individual binary bar codes. The sensor having an EMR source (10) and an array of EMR sensitive detectors (9) fixed with respect to the housing. The source irradiating the surface and the array receiving incident reflected EMR. A pattern produced by incident EMR on the array resulting from the alternate regions of low and high reflectivity on the surface. The pattern processed by a processor (11) to derive the absolute angular position of the regions with respect to the housing, providing a measure of the absolute angular position of the rotatable body with respect to the housing.