# US 2017/0284831 A1 · Sensor for detecting a period magnetic field > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0284831 A1 - Document ID: US20170284831A1 - Status: Published application - Kind: A1 - Application number: 15/474,780 - Filed: 2017-03-30 - Published: 2017-10-05 - Earliest claimed: 2016-03-31 - Assignees: Ntn-Snr Roulements - Applicants: Ntn-Snr Roulements - Inventors: Christophe Duret; Cyril Peterschmitt - Web page: https://patentgrep.com/patent/US20170284831A1 ## CPC - G01D 5/165: by relative movement of a point of contact {or actuation} and a resistive track - G01D 5/16: by varying resistance - G01R 33/093: {using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00)} - G01R 33/098: {comprising tunnel junctions, e.g. tunnel magnetoresistance sensors} - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A sensor including a measuring assembly integrating at least one magnetoresistive element having a stack of two conductive magnetic layers, respectively reference and sensitive, the reference layer having magnetic anisotropy in the direction X and the sensitive layer having a direction Y, polarization permanent magnet having a surface extending in a plane of directions X and Y and having a symmetry plane of directions X and Z, the measuring assembly being disposed with respect to the symmetry plane of the polarization magnet so that the layers of the magnetoresistive element are disposed in a plane parallel to the surface while being offset from said plane in the direction Y by a distance (Δy) that is arranged so that the magnetic field of the polarization magnet orients the magnetisation of the sensitive layer in the direction Y. ## Claims ### Claim 1 A sensor for detecting a periodic magnetic field comprising a measuring assembly integrating at least one magnetoresistive element the electrical resistance of which varies as a function of the amplitude of the component of said periodic magnetic field in a direction X, said magnetoresistive element comprising a stack of two conductive magnetic layers, respectively reference and sensitive, between which a separation layer is disposed so that the electrical resistance of said stack is dependent on the relative orientation of the magnetization of the reference and sensitive layers, said sensor further comprising an electronic circuit arranged so as to use the variations in said electrical resistance in order to deliver a signal representing the magnetic field to be detected, the reference layer having magnetic anisotropy in the direction X and the sensitive layer having a direction Y perpendicular to the direction X, said sensor including a permanent polarization magnet having a surface extending in a plane of directions X and Y and having a symmetry plane of directions X and Z, the direction Z being perpendicular to the directions X and Y and being the direction along which the magnetic field of said magnet mainly extends, the measuring assembly being disposed with respect to the symmetry plane of the polarization magnet so that the layers of the magnetoresistive element are disposed in a plane parallel to the surface while being offset from said plane in the direction Y by a distance (Δy) that is arranged so that the magnetic field of the polarization magnet orients the magnetization of the sensitive layer in the direction Y while allowing variations in the orientation of said magnetization according to the component of the direction X of the magnetic field to be detected, said variations in magnetization causing a linear variation in the electrical resistance of the magnetoresistive element over a magnetic field range to be detected. ### Claim 2 (depends on 1) The detection sensor according to claim 1, the sensitive layer having a preferential direction of magnetization in the direction Y. ### Claim 3 (depends on 1) The detection sensor according to claim 1, the measuring assembly including a plurality of magnetoresistive elements that are disposed in a linear geometry extending in the direction X. ### Claim 4 (depends on 3) The detection sensor according to claim 3, the magnetoresistive elements being included in the measuring assembly in a Wheatstone bridge. ### Claim 5 (depends on 3) The detection sensor according to claim 3, the magnetoresistive elements being included in the measuring assembly in a current loop. ### Claim 6 (depends on 1) The detection sensor according to claim 1, the measuring assembly being disposed opposite a central part of the surface of the polarization magnet. ### Claim 7 (depends on 1) The detection sensor according to claim 1, the measuring assembly being formed on one face of an electronic card, the other face of said card being fixed to the surface of the polarization magnet. ### Claim 8 (depends on 1) The detection sensor according to claim 1, the polarization magnet being produced from ferrite. ### Claim 9 (depends on 1) The detection sensor according to claim 1, the measuring assembly being offset from the symmetry plane by a distance (Δy) that lies between 5 and 15% of the dimension (Dy) of the surface (3) of the polarization magnet in the direction Y. ### Claim 10 (depends on 1) The detection sensor according to claim 1, the magnetoresistive element being of the tunnel effect type. ### Claim 11 (depends on 1) A system for determining at least one movement parameter of a member able to move with respect to a fixed structure, said system comprising: an encoder securable to the movable member so as to move conjointly with it, said encoder being arranged so as to deliver a periodic magnetic field that represents the movement of the encoder; a detection sensor according to claim 1 that is securable to the fixed structure with the measuring assembly at a detection distance from the magnetic field; and a computing device for determining the movement parameter of the movable member according to variations in electrical resistance of the measuring assembly. ### Claim 12 (depends on 11) The determination system according to claim 11, the encoder comprising at least one multipole magnetic track that is able to emit a magnetic field, the component of which in the direction X varies pseudosinusoidally according to the movement of said track relative to the measuring assembly. ### Claim 13 (depends on 11) The determination system according to claim 11, the encoder having a ferromagnetic structure that is arranged so as to modify the magnetic field emitted by the polarization magnet so as to deliver a component of said field in the direction X that varies pseudosinusoidally according to the movement of said structure relative to the measuring assembly.