A measuring device for a spindle or for a rotary table includes at least two first and second position sensing elements and a scale element, having a first and second graduations and being rotatable about an axis of rotation relative to the position sensing elements. The first graduation includes regular structures arranged in parallel next to one another along a first direction, having a directional component in the circumferential direction. The second graduation includes regular structures arranged in parallel next to one another along a second direction, having a directional component in the axial direction. The first position sensing elements are offset from one another in the circumferential direction, and are able to scan the first graduation so that the position of the scale element in a plane having an orthogonal orientation to the axis of rotation is determinable. In addition, at least one of the first position sensing elements is able to determine an angular position of the scale element in relation to the first position sensing elements in absolute terms within and across a rotation. The second position sensing elements are offset from one another in the circumferential direction, and are able to scan the second graduation, and the axial position of the scale element is able to be determined.

In a length or position measuring system which has an at least locally substantially linear measuring gauge and at least one sensor able to be moved relative to the measuring gauge wherein the measuring gauge includes an incremental track and at least one absolute track and wherein the incremental track and the at least one absolute track have pole pairs arranged in the longitudinal direction of the measuring gauge, it is provided in particular that at least one pole pair of the absolute track is phase-shifted relative to a corresponding pole pair of the incremental track.

The various embodiment of the present disclosure provides a system to define and identify an absolute mechanical reference position for a rotating element, The system comprises a radial ring magnet comprising plurality of pole pairs mounted to the rotating element, a first magnetic sensor in proximity of the radial ring magnet to detect angular position of said rotating element, at least one second magnetic sensor in proximity of the radial ring magnet to detect the passage of each of the pole pair and a control module adapted to define said absolute mechanical position by computing a unique first set of feature values for each of said plurality of pole pairs based on responses of said first magnetic sensor and said second magnetic sensor. The first set of feature values is stored in a memory unit.

An absolute encoder includes a scale having a sequence of marks, a detector configured to detect a signal corresponding to a plurality of marks of the scale, and a processor configured to obtain an absolute position corresponding to the signal. The processor is configured to select code sequences, from a group of code sequences corresponding to absolute positions, as a candidate group for a code sequence corresponding to the signal, and to select the code sequence corresponding to the signal from the candidate group.

A rotary position encoder includes a detection unit and a scale co-configured and co-operative to detect a relative rotational position and to generate a position output accordingly. The scale has a scale pattern according to a linear-feedback shift register (LFSR) pseudo-random code, which is a non-maximal length code having a seed value, tap positions, and modified least-significant bit position(s) of code words that satisfy rotary constraint by which each code word follows in sequence from the adjacent code word.

In a length or position measuring system which has an at least locally substantially linear measuring gauge and at least one sensor to be moved relative to the measuring gauge, wherein the measuring gauge includes an incremental track and at least one absolute track and wherein the incremental track and the at least one absolute track have poles arranged in the longitudinal direction of the measuring gauge, the poles of the at least one absolute track form at least two regions in the sensor with different field strengths or signal amplitudes.

There is provided a displacement measuring apparatus capable of being used in a vacuum environment. The displacement measuring apparatus includes a scale and a detection head part disposed in such a manner as to be relatively displaceable to the scale and as to face the scale with a predetermined gap. The detection head part detects a displacement or position relative to the scale. The scale is disposed in a vacuum. The detection head part is housed in a housing holder separating an atmospheric environment side from a vacuum environment side. In a gap between the detection head part and the scale, the housing holder includes a relay means for passing a detection signal between the detection head part and the scale.

In a length or position measuring system which has an at least locally substantially linear measuring gauge and at least one sensor to be moved relative to the measuring gauge, wherein the measuring gauge includes an incremental track and at least one absolute track and wherein the incremental track and the at least one absolute track have poles arranged in the longitudinal direction of the measuring gauge, the poles of the at least one absolute track form at least two regions in the sensor with different field strengths or signal amplitudes.

In a length or position measuring system which has an at least locally substantially linear measuring gauge and at least one sensor able to be moved relative to the measuring gauge wherein the measuring gauge includes an incremental track and at least one absolute track and wherein the incremental track and the at least one absolute track have pole pairs arranged in the longitudinal direction of the measuring gauge, it is provided in particular that at least one pole pair of the absolute track is phase-shifted relative to a corresponding pole pair of the incremental track.