An object is to respectively excite transmission coils with different voltages using a single power supply with low power consumption in an electromagnetic induction type encoder.

A detection head of an encoder includes a voltage adjustment circuit and a plurality of excitation circuits. The excitation circuit includes a resonant circuit that includes a driving capacitor and a transmission coil connected in series and generates an alternate-current magnetic field inducing currents in scale coils disposed in a plurality of scale tracks on a scale by connecting both ends of the resonant circuit in a state in which the driving capacitor is charged. The voltage adjustment circuit includes a first transformer capacitor and controls a charging voltage of the driving capacitor in a single excitation circuit using the charged first transformer capacitor.

A differential angle sensor for measuring a differential angle between an input shaft and an output shaft includes a target assembly fixed to rotate with one of the shafts and a ring magnet with equidistantly spaced magnet segments fixed to rotate with the other one of the shafts. The target assembly includes four identical targets extending about the common axis parallel and axially spaced apart from one another, and each having a plurality of wedge-shaped teeth extending radially toward the ring magnet. A first magnetic field sensor is disposed between first and second targets for measuring a first magnetic field strength therebetween. A second magnetic field sensor is disposed between third and fourth targets for measuring a second magnetic field strength. The targets are all circumferentially offset relative to one another such that the magnetic field strengths each vary with the differential angle between the shafts and differently from one-another.

The present invention provides a multi-turn absolute torque angle sensor module containing a main gear magnet which includes a first magnet part in which a master track and a nonius track, in which magnets having different polarities are alternately disposed, vertically disposed on a circumferential surface portion of the first magnet part and the polarity distributions of the master track and the nonius track are to be shifted from each other by a difference of one or more polarities.

A rotary encoder that is capable of securing a sufficient synthesis tolerance while achieving miniaturization is provided. The rotary encoder 1 includes a rotor 3, a stator 4, and a calculating unit 5 for calculating the rotation angle. The rotor 3 has a first rotor pattern 31 with a plurality of unit patterns 310 arranged along the measurement direction around the rotating shaft 2, and a second rotor pattern 32 with fewer unit patterns 320 than the plurality of unit patterns 310 in the first rotor pattern 310 arranged along the measurement direction. The number of the plurality of unit patterns 310 of the first rotor pattern 31 and the number of the plurality of unit patterns 320 of the second rotor pattern 32 are provided such that the maximum common divisor therebetween is two or more. The calculating unit calculates the rotation angle of the rotor 3 based on the detection signals from the first rotor pattern 31 and the second rotor pattern 32.

A method of assembling a position sensing arrangement for sensing the position of a revolute joint of an articulated structure. The position sensing arrangement comprises a magnetic sensor assembly and a disc having a first magnetic ring with j magnetic pole pairs and a second magnetic ring with k magnetic pole pairs. A boundary of the disc is constrained by the articulated structure. The method comprises: determining a number of pole pairs of the first magnetic ring to be an integer p such that the first magnetic ring is separated from the constrained boundary by at least the magnetic sensor assembly; determining a number of pole pairs of the second magnetic ring to be an integer q such that the second magnetic ring is separated from the first magnetic ring by a predetermined distance; and if p and q are co-prime: selecting j to be p and k to be q; and assembling the position sensing arrangement by mounting the disc to the articulated structure such that both the disc and the revolute joint are permitted to rotate about the same axis.

A method for calibrating a position measurement system includes receiving measurement data from the position measurement system and determining that the measurement data includes periodic distortion data. The position measurement system includes a nonius track and a master track. The method also includes modifying the measurement data by decomposing the periodic distortion data into periodic components and removing the periodic components from the measurement data.

The present invention provides an apparatus for sensing rotor location, the apparatus comprising: a central shaft; a magnet coupled to the central shaft; a sensor portion is disposed correspond to the magnet; wherein the sensor portion comprising a substrate, a first group including a first Hall sensor and a third Hall sensor disposed on the substrate, and a second group including a second Hall sensor and a fourth Hall sensor, the first Hall sensor and the third Hall sensor are arranged to overlap in a radial direction about the central shaft and the second Hall sensor and the fourth Hall sensor are arranged to overlap in a radial direction about the central shaft.

A motor for sensing a rotor location is provided, the motor comprising a shaft, a sensing magnet including a main magnet and a sub-magnet coupled to the shaft and a substrate disposed on the sensing magnet. The substrate includes a plurality of first hall sensors and a plurality of second hall sensors spaced apart from the shaft by a first distance, and a plurality of third hall sensors and a plurality of fourth hall sensors spaced apart from the shaft by a second distance larger than the first distance.

A magnetic field sensor for sensing an absolute position of a target object can include a first one or more magnetic field sensing elements disposed proximate to a first portion of the target object, the first one or more magnetic field sensing elements operable to generate a first magnetic field signal responsive to the movement of the first portion; a second one or more magnetic field sensing elements disposed proximate to a second portion of the target object, the second one or more magnetic field sensing elements operable to generate a second magnetic field signal responsive to the movement of the second portion; a position detection module coupled to use the first and second magnetic field signals to generate a position value indicative of the absolute position; and an output format module coupled to receive the position value and to generate a position signal from the magnetic field sensor indicative of the absolute position.

The invention relates to an assembly comprising an encoder (1) secured in rotation to the member, said encoder comprising a primary magnetic track (2) and a secondary magnetic track (3) and a sensor (4) having two patterns (5) of sensitive elements which are suitable for detecting the signals supplied by the tracks (2, 3) of the encoder (1), each pattern (5) being arranged at reading distance from a track (2, 3) to form a representative signal of the position of said track, the sensitive elements of a first pattern (5) are based on a magnetoresistive material wherein the resistance varies according to the magnetic signal of the track (2, 3) to be detected, said first pattern being arranged at reading distance from a second track (3) having 2N1 magnetic pole pairs, the sensitive elements of the second pattern (5) being based on an anisotropic magnetoresistive material, said second pattern being arranged at reading distance from a primary track (2) having N magnetic pole pairs.