Patent ID: 6175414
Filing Date: 2001-01-16
Classification: G01D

Abstract:
An optical position measuring device for determining a relative position of two objects movable with respect to each other in a measuring direction, by generating a reference pulse signal corresponding to at least one defined relative reference position, the position measuring device comprising:a scale having a scale reference mark structure, the scale being connected to one of the two objects and the scale reference mark structure being composed of n (n=2,3,4 . . . ) blocks disposed in the measuring direction, the scale reference mark structure blocks having a plurality of sequentially arranged partial areas of varying optical characteristics disposed in the measuring direction; anda scanning unit connected to the other of the objects and including a scanning plate with a plurality of detector elements and a scanning reference mark structure composed of n scanning reference blocks arranged sequentially in the measuring direction, the scanning reference mark structure blocks having assigned to them corresponding detector elements;wherein at least a first group of blocks of one of the scale reference and scanning reference mark structures is configured, at the reference position in the plane of a respective other one of the scanning reference and scale reference mark structures, to supply an intensity distribution that is identical to the structure of the associated first group of blocks,wherein at least a second group blocks of another one of the scale reference and the scanning reference mark structures, in a plane of a respective other one of the scanning reference and scale reference mark structures, supplies an intensity distribution that is complementary to the structure of the associated second group of blocks,and wherein the detector elements are interconnected such that output signals of the detector elements of each group of blocks are connected to each other to generate a reference pulse output signal resulting from the output signals, said reference pulse output signal having a maximum or a minimum at the defined relative position of the two objects.