# US 7,612,559 B2 · Method and system for continuous position detection of moving parts in relation to each other > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,612,559 B2 - Document ID: US7612559B2 - Status: Granted - Kind: B2 - Application number: 11/480,024 - Filed: 2006-06-29 - Published: 2008-01-03 - Granted: 2009-11-03 - Earliest claimed: 2006-06-29 - Assignees: Nokia Corporation - Inventors: Vesa Koivuaho - Web page: https://patentgrep.com/patent/US7612559B2 ## CPC - G01R 33/02: Measuring direction or magnitude of magnetic fields or magnetic flux (G01R33/20 takes precedence) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract The invention relates to a method and system for continuous position detection using a contact-free detection technology. An arrangement includes a magnetic field source and magnetometer sensor, where the magnetic field source is adapted to generate a first magnetic field density and a sequential second magnetic field density determined by said magnetometer sensor. The sign of the determined first magnetic field generated by said magnetic field source is opposite than the second determined magnetic field generated by said magnetic field source. In addition the arrangement is adapted to compensate an offset drifting caused by the magnetic field environment and to determine a distance between the magnetic field source and magnetometer sensor based on the difference of the first magnetic field density and the sequential second magnetic field density determined by said magnetometer sensor. ## Claims ### Claim 1 An apparatus comprising: a magnetic field source configured to generate a first magnetic field density of a first magnetic field with a first field polarization and, at a later time, a sequential second magnetic field density of a second magnetic field with a second field polarization, where the second field polarization differs from the first field polarization, a magnetometer sensor configured to determine said two different sequential magnetic field densities of said magnetic fields with the different field polarization generated by said one magnetic field source, and a measurement unit configured to determine a distance between the magnetic field source and magnetometer sensor based on a difference of the first magnetic field density and the sequential second magnetic field density determined by said magnetometer sensor and to compensate an offset drifting caused by a magnetic field environment based at least in part on the determined distance. ### Claim 2 (depends on 1) An apparatus according to claim 1, wherein the magnetic field source is a coil operated by a current supply. ### Claim 3 (depends on 1) An arrangement according to claim 1, wherein the magnetic field source is a permanent magnet and a polarity of the magnetic field is changed turning the permanent magnet around its axis by an actuator. ### Claim 4 (depends on 1) An arrangement according to claim 1, wherein the magnetometer sensor is 1 to 3 dimensional magnetometer sensor. ### Claim 5 (depends on 1) An apparatus according to claim 1, wherein the magnetometer sensor is further configured to determine a relational speed of the magnetic field source and the magnetometer sensor. ### Claim 6 (depends on 1) An apparatus according to claim 1, wherein the magnetometer sensor is at least a 2 dimensional magnetometer sensor and the magnetometer sensor is further configured to determine an angle between the magnetic field source and the magnetometer sensor. ### Claim 7 A method comprising: generating by a magnetic field source of a first magnetic field density of a first magnetic field with a first field polarization and, at a later time, generating a sequential second magnetic field density of a second magnetic field with a second field polarization, where the second field polarization differs from the first field polarization, determining said two different sequential magnetic field densities of said magnetic fields with the different field polarization generated by said one magnetic field source by a magnetometer sensor, determining a distance between the magnetic field source and magnetometer sensor based on a difference of the first magnetic field density and the sequential second magnetic field density determined by said magnetometer sensor, and compensating an offset drifting caused by a magnetic field environment based at least in part on the determined distance. ### Claim 8 (depends on 7) A method according to a claim 7, wherein the magnetic field source is a coil operated by a current supply. ### Claim 9 (depends on 7) An arrangement according to claim 7, wherein the magnetic field source is a permanent magnet and a polarity of the magnetic field is changed turning the permanent magnet around its axis by an actuator. ### Claim 10 (depends on 7) An arrangement according to claim 7, wherein the magnetometer sensor is 1 to 3 dimensional magnetometer sensor. ### Claim 11 (depends on 7) An arrangement according to claim 7, wherein a relational speed of the magnetic field source and the magnetometer sensor is also determined. ### Claim 12 (depends on 7) An arrangement according to claim 7, wherein the magnetometer sensor is at least 2 dimensional magnetometer sensor and an angle between the magnetic field source and the magnetometer sensor is also determined. ### Claim 13 A mobile device comprising: a first part and a second part movable attached to said first part, a magnetic field source in said first part configured to generate a first magnetic field density of a first magnetic field with a first field polarization and to generate, at a later time, a sequential second magnetic field density of a second magnetic field with a second field polarization, where the second field polarization differs from the first field polarization, a magnetometer sensor in said second part configured to determine said two different sequential magnetic field densities of said magnetic fields with the different field polarization generated by said one magnetic field source, and a measurement unit configured to determine of a distance between the magnetic field source and magnetometer sensor based on a difference of the first magnetic field density and the sequential second magnetic field density determined by said magnetometer sensor, and thereby to determine the distance between the first and second part of the mobile device, and to compensate an offset drifting cuased by a magnetic field environment based at least in part on the determined distance between the first and second part of the mobile device. ### Claim 14 (depends on 13) A mobile device according to claim 13, wherein the magnetic field source is a coil operated by a current supply. ### Claim 15 (depends on 13) A mobile device according to claim 13, wherein the magnetic field source is a permanent magnet and a polarity of the magnetic field is changed by turning the permanent magnet around its axis by an actuator. ### Claim 16 (depends on 13) A mobile device according to claim 13, wherein the magnetometer sensor is a 1 to 3 dimensional magnetometer sensor. ### Claim 17 (depends on 13) A mobile device according to claim 13, wherein the measurement unit is further configured to determine a relational speed of the magnetic field source and the magnetometer sensor, and thereby the relational speed of the first and second part of the mobile device. ### Claim 18 (depends on 13) A mobile device according to claim 13, wherein the magnetometer sensor is at least a 2 dimensional magnetometer sensor and the measurement unit is further configured to determine an angle between the magnetic field source and the magnetometer sensor, and thereby the angle between the first and second part of the mobile device. ### Claim 19 (depends on 13) A mobile device according to claim 13, wherein the mobile device is a mobile phone. ### Claim 20 (depends on 13) A mobile device according to claim 13, wherein the parts are configured to slide in relation to each other. ### Claim 21 (depends on 13) A mobile device according to claim 13, wherein the parts are rotatably hinged to each other around at least one axis. ### Claim 22 A computer program product comprising machine readable instructions stored on a computer readable medium having computer executable components configured to control: a generation by a magnetic field source of a first magnetic field density of a first magnetic field with a first field polarization and, at a later time, generation of a sequential second magnetic field density of a second magnetic field with a second field polarization, where the second field polarization differs from the first field polarization, a determination of said two different sequential magnetic field densities of said magnetic fields with the different field polarization generated by said one magnetic field source by a magnetometer sensor, a determination of a distance between the magnetic field source and magnetometer sensor based on a difference of the first magnetic field density and the sequential second magnetic field density determined by said magnetometer sensor, and a compensation of an offset drifting caused by a magnetic field environment based at least in part on the determined distance. ### Claim 23 (depends on 22) A computer program product according to claim 22, having further a computer executable component configured to control a current supply operating a coil generating the magnetic field. ### Claim 24 (depends on 22) A computer program product according to claim 22, having further a computer executable component configured to control a changing of a polarity of the magnetic field generated by a permanent magnet by turning the permanent magnet around its axis by an actuator. ### Claim 25 (depends on 22) A computer program product according to claim 22, having further a computer executable component configured to control a determination of a relational speed of the magnetic field source and the magnetometer sensor, and thereby the relational speed of the first and second part of the mobile device. ### Claim 26 (depends on 22) A computer program product according to claim 22, having further a computer executable component configured to control a determination of an angle between the magnetic field source and the magnetometer sensor, and thereby the angle between the first and second part of the mobile device, when the magnetometer sensor is at least a 2 dimensional magnetometer sensor.