Method of determining a position of a sensor device relative to a magnetic source, includes: a) determining a first and a second magnetic field component at a first sensor location; b) determining a third and a fourth magnetic field component at a second sensor location; c) determining a first difference of the first and third component, and determining a second difference of the second and fourth component, and determining a first angle based on a ratio of the first and second difference; d) determining a first sum of the first and third component, and determining a second sum of the second and fourth component; e) determining a second angle based on a ratio of said first and second sum; f) comparing the first and second angle to detect error.

An encoder is provided that is capable of suppressing accuracy deterioration even if a scale is disposed in a tilted manner with respect to a receiving unit by being rotated around an axis (i.e., a rotation axis) orthogonal to a receiving surface. The encoder 1 includes scale 2 and detection head 3. The detection head 3 includes light source (transmitting unit) 4 and light-receiving unit (receiving unit) 5. The light-receiving unit includes light-receiving surface (receiving surface) 50 and converts light received at the light-receiving surface 50 into differential detection signals with two phases and outputs the same. The light-receiving surface 50 includes element array group 7 including four element arrays 71-74 provided in a parallel manner along an orthogonal direction, with each element array 71-74 including a plurality of light-receiving elements (receiving elements) 500. The plurality of element arrays 71-74 in the element array group 7 are disposed at positions where the sum of: (i) a distance in the orthogonal direction from a reference position to a positive phase signal element array 71, 72; and (ii) a distance in the orthogonal direction from the reference position to the negative phase signal element array 73, 74, is the same for all the phases of the at least two phases.

A magnetic linear position detector includes a stator and a mover that is movable along a first direction with respect to the stator. One of the stator and the mover includes a magnetic detector, and the other of the stator and the mover includes a magnet. The magnet has a first face facing the magnetic detector, and the first face is provided alternately with N poles and S poles along the first direction. The magnet includes a first region and a second region provided on each side of the first region along the first direction. In the first region, a length along a second direction perpendicular to the first face is constant. In the second region, a length along the second direction is different from the length in the first region.

A position sensor system is arranged for determining a position of a sensor device movable along a predefined path relative to a magnetic source. The system includes the magnetic source and the sensor device. The magnetic source has a first plurality of magnetic pole pairs arranged along a first track and a second plurality of magnetic pole pairs arranged along a second track, centrelines of the tracks are spaced apart by a predefined track distance. The sensor device is configured for measuring at least two orthogonal magnetic field components at a first sensor location, and at least two second orthogonal magnetic field components at a second sensor location. The first and second sensor location are spaced apart by a predefined sensor distance smaller than the predefined track distance, in a direction transverse to the tracks.

An encoder for detecting rotation information of a first rotation shaft includes a first detector which detects a pattern provided in the first rotation shaft, a first housing case which houses the pattern provided in the first rotation shaft and the first detector, a second housing case which houses at least a part of a shaft portion different from a portion where the pattern is provided, of the first rotation shaft, and an adjusting mechanism which adjusts at least one of an atmospheric pressure and a temperature in the first housing case to be higher than at least one of an atmospheric pressure and a temperature in the second housing case. The inflow of the high-humidity air from a motor into the encoder is prevented or suppressed, so that the condensation in the encoder can be prevented or suppressed.

The rotation detection apparatus including an annular member, a scale member having flexibility and being fixed to a circumferential portion of the annular member, and a detector facing the scale member and configured to detect relative rotation between the scale member and the detector. The circumferential portion of the annular member includes multiple convex portions and multiple concave portions along a circumferential direction of the annular member. The scale member is in contact with the multiple convex portions. Both ends, in the circumferential direction, of the scale member are fixed to the circumferential portion.

An inductive angle measuring device includes a scanning element and a scale element having scale tracks. First and third scale tracks have an equal first number of scale structures, and a second scale track has a different number of scale structures. The scale tracks are arranged circumferentially and concentrically about an axis, such that the first scale track is located radially inwardly, the second scale track is located radially between the first scale track and the third scale track, and the third scale track is located radially outwardly. The scanning element includes receiver conductors by which the signals having angle-related signal periods can be generated. The first signal period is equal to the third signal period. An overall signal can be generated from the first signal and the third signal and can be combined with the second signal for determining absolute angle position information.

The invention relates to a system comprising a coder that has an alternation of North and South magnetic poles separated by transitions extending along a helix of pitch p and of angle α, the magnetic track having N.sub.pp pairs of North and South poles and a polar width L.sub.p measured along a normal to the transitions which are: N.sub.pp=πa/l and L.sub.p=p.Math.cos α. The invention also includes at least one sensor able to detect the rotating magnetic field in a plane perpendicular to the magnetic track and to the transitions by means of a mounting of at least two sensitive magnetic elements. The mounting being disposed at a radial reading distance from the magnetic track and being arranged to deliver signals in quadrature.

There is provided an optical encoder with alignable relative positions between elements including an encoding medium, a sensor package and a memory. The sensor package includes a photodiode array and two alignment photodiodes opposite to the encoding medium. The memory records an alignment pattern associated with output signals of the two alignment photodiodes when the encoding medium and the sensor package are at nominal operating positions. When the encoding medium and the sensor package are not at the nominal operating positions, the relative position alignment is performed by adjusting current relative positions between the encoding medium and the sensor package to cause a current pattern associated with output signals of the two alignment photodiodes to be identical to the alignment pattern.

A rotation detection device includes: a detector arranged with a gap to a rotating body in which rotation position information is periodically provided at regular intervals, and detecting a magnetic change as a rotation position of the rotating body; and a signal processor acquiring the rotation position information. The detector has first and second magnetic elements arranged with an interval of a/2 in a rotation direction. Each regular interval is defined as a. The first magnetic element outputs a first signal having a period corresponding to the regular intervals. The second magnetic element outputs a second signal having an opposite phase to the first signal and the period. The signal processor acquires a differential signal between the first and second signals as the rotation position information.