Position measuring system using two groups of magnetoresistors spaced differently
First Claim
1. A position measuring system for measuring the relative position of a first object with respect to a second object, the first object and second objects being movable with respect to each other, comprising:
- a periodic graduation located on the first object, the periodic graduation having an index period of t;
a scanning unit located on the second object for scanning the periodic graduation, the scanning unit comprising;
a first base arrangement facing the periodic graduation, the base arrangement including;
a first group of at least four magneto-resistive elements, the first group spanning a distance no greater than the index period of the graduation;
a second group of at least four magneto-resistive elements located adjacent to the first group, the second group spanning a distance greater than the index period of the graduation,the first and second groups separated by a predetermined distance so that a center point exists between the two groups; and
a plurality of conductors for connecting elements of the first group to elements of the second group without crossing the conductors, wherein the Nth element of the first group is directly connected to the Nth element of the second group, where N represents the number element of the first and second groups from the center point.
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Accused Products
Abstract
In a position measuring system a period graduation is scanned by a scanning unit using two groups of respectively four magneto-resistive elements. To avoid crossings of the connecting strip conductors of the magneto-resistive elements and short-wave interference effects on the measuring accuracy, the magneto-resistive elements of the first group extend over one index period of the graduation at a mutual separation of t/4, while every magneto-resistive element of the second group is disposed in adjoining index periods of the graduation at a mutual separation of 3/4(t). Starting at the center of both groups, the respectively Nth magneto-resistive element of the first group is connected to the Nth magneto-resistive element of the second group free of crossings.
23 Citations
20 Claims
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1. A position measuring system for measuring the relative position of a first object with respect to a second object, the first object and second objects being movable with respect to each other, comprising:
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a periodic graduation located on the first object, the periodic graduation having an index period of t; a scanning unit located on the second object for scanning the periodic graduation, the scanning unit comprising; a first base arrangement facing the periodic graduation, the base arrangement including; a first group of at least four magneto-resistive elements, the first group spanning a distance no greater than the index period of the graduation; a second group of at least four magneto-resistive elements located adjacent to the first group, the second group spanning a distance greater than the index period of the graduation, the first and second groups separated by a predetermined distance so that a center point exists between the two groups; and a plurality of conductors for connecting elements of the first group to elements of the second group without crossing the conductors, wherein the Nth element of the first group is directly connected to the Nth element of the second group, where N represents the number element of the first and second groups from the center point. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A scanning unit for scanning a periodic graduation comprising:
a first base arrangement facing the periodic graduation, the base arrangement including; a first base arrangement facing the periodic graduation, the base arrangement including; a first group of at least four magneto-resistive elements, the first group spanning a distance no greater than the index period of the graduation; a second group of at least four magneto-resistive elements located adjacent to the first group, the second group spanning a distance greater than the index period of the graduation, the first and second groups separated by a predetermined distance so that a center point exists between the two groups; and a plurality of conductors for connecting elements of the first group to elements of the second group without crossing the conductors, wherein the Nth element of the first group is directly connected to the Nth element of the second group, where N represents the number element of the first and second groups from the center point. - View Dependent Claims (19, 20)
Specification