Patent ID: 7159781
Filing Date: 2007-01-09
Classification: G01D

Abstract:
1. A scanning unit for a position measuring device for scanning a measuring graduation of the position measuring device, comprising: a carrier; a scanning structure provided on the carrier and adapted to generate a periodic stripe pattern by interaction of electromagnetic radiation used to scan the measuring graduation; and a detector arrangement adapted to detect the stripe pattern, the detector arrangement including a plurality of detector elements of different phases arranged one after another and are adapted to generate output signals having a phase shift represented by a respective phase; wherein the detector elements of different phases are arranged one after another to form a periodic pattern, exactly one region of the scanning structure assigned to each of the detector elements, the detector elements combined to form two detector groups, at least detector elements of a same phase each belong to the same detector group, the detector elements within a detector group interconnected to generate a detector signal; and wherein bars of the scanning structure, corresponding to each region of the scanning structure assigned to each of the detector elements, are formed and arranged such that a totality of the bars assigned to a first detector group and a totality of the bars assigned to a second detector group each cover an active area of equal size on the carrier of the scanning structure during position measurement, the area covered by the totality of bars assigned to the first detector group and the area covered by the totality of bars assigned to the second detector group have a same area center of gravity.