Dr. Johannes Heidenhain Gmbh

Gerald Metz

Alfons Spies

Holmer Dangschat

Christian Spaeth

A device for determining the position of an object that is movable along at least one displacement direction, the or each displacement direction having assigned to it one length measuring device for measuring the position of the object along the respective spatial direction, includes: at least one scale extending along a displacement direction of the object to be measured as a first component of the respective length measuring device; a scanning head for scanning the scale as a second component of the respective length measuring device such that a change in the position of the scale with respect to the scanning head along the associated displacement direction of the object to be measured is measurable, one of the two components of the respective length measuring device being moved together with the object to be measured along the respective displacement direction when the latter is moved; and a device for determining the distance of the component of the respective length measuring device, which is movable together with the object to be measured, from the object to be measured along the measuring direction of the associated length measuring device. The device for determining the distance of the component of the respective length measuring device, which is movable together with the object to be measured, from the object to be measured includes a measuring graduation as a first module and an associated measuring head as a second module, one of the two modules being provided on the object to be measured and the other of the two modules being provided on the component of the length measuring device that is movable together with the object to be measured.

Device for determining the position of an object movable along at least one displacement direction

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.

Position measuring system using two groups of magnetoresistors spaced

A position measuring instrument for measuring the relative position of two objects movable relative to one another. The position measuring instrument comprises a periodic measurement scale division having a period t and a scanner unit, wherein the scanner unit and the periodic measurement scale division move relative to one another in a measuring direction. In addition, the scanner unit comprises four groups (A-D) each comprising at least four magnetoresistive elements (A.sub.n -D.sub.n) (n=1, 2, 3, 4, . . .), which are interconnected in the form of a series-parallel circuit to form a half bridge circuit having an upper branch and a lower branch. The upper branch comprises a magnetoresistive element from each group (A-D) and the lower branch comprises a corresponding magnetoresistive element from each group (A-D). Furthermore, the magnetoresistive elements of the upper branch are offset from the corresponding magnetoresistive elements of the lower branch by t/2. The position measurement instrument further comprises an evaluation device to form position measurement values from position-dependent output signals generated by the magnetoresistive elements in response to relative movement between the periodic measurement scale division and the scanner unit.

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St. Georgen, Germany

Gerald Metz