Patent ID: 7129858
Filing Date: 2006-10-31
Classification: G01D,H03M

Abstract:
1. An encoding system for determining position and position changes of a moving member, comprising: a sequence of encoder marks forming incremental patterns and at least one index pattern, wherein two subsequent incremental patterns are indicative of an incremental position-change of the moving member and the index pattern is indicative of a reference position of the moving member; a sensor configured to view a section of the encoder-mark sequence, wherein the viewed section of the encoder-mark sequence carries redundant incremental position-change information at least in regions not disturbed by the index pattern; and an analyzer arranged to analyze an encoder-mark pattern in the viewed section with regard to the incremental patterns and the index pattern and to generate, in response to a pattern match found, an incremental-position-change signal and an index signal, wherein the signals are generated only after confirming a correlation greater than selected thresholds between the encoder-mark pattern and the incremental patterns and the index pattern.