Linear position and rotary position magnetic sensors, systems, and methods

Patent metadata

Field	Value
Publication number	US-9863788-B2
Application number	US-201414482457-A
Country	US
Kind code	B2
Filing date	Sep 10, 2014
Priority date	Sep 10, 2014
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

Embodiments relate to a position sensor comprising a magnetic target. The magnetic target includes a magnetic multipole configured to generate a magnetic field. The magnetic field has three mutually-perpendicular components at a first region. Sensor elements can be configured to measure these field components at the first region. In embodiments, comparing the amplitudes of the components can be used to determine a global position, and the instantaneous values of these components can be used to determine a local position.

First claim

What is claimed is:

1. A position sensor comprising:
a magnetic target comprising a magnetic multipole configured to generate a magnetic field comprising, at a first region, a first component, a second component, and a third component, wherein the first, second, and third components are mutually perpendicular to one another at the first region;
a sensor die comprising:
a first sensor element configured to measure the first component at the first region; and
a second sensor element configured to measure at least one of the second or third components substantially at the first region;

a circuitry configured to: determine a first amplitude corresponding to an output from the first sensor element, determine a second amplitude corresponding to an output from the second sensor element, and produce a signal corresponding to the first amplitude divided by the second amplitude; and
a third sensor element configured to measure at least one of the first, second, or third components, determine a global position based upon the signal, and determine a local position based upon an output of the third sensor element.

2. The position sensor of claim 1 , wherein the magnetic multipole comprises a set of pole pairs, wherein the first and second sensor elements are configured to provide signal amplitudes to determine a global position of the magnetic target to within 360°/N, wherein N is a number of pole pairs in the set of pole pairs.

3. The position sensor of claim 1 , wherein the magnetic multipole comprises a ring mounted eccentrically on a first portion having a center of rotation.

4. The position sensor of claim 1 , wherein the magnetic multipole comprises a thick portion and a thin portion.

5. The position sensor of claim 1 , wherein the magnetic multipole comprises a non-toroidal geometry.

6. The position sensor of claim 4 , wherein the magnetic multipole comprises a discontinuity.

7. The position sensor of claim 1 ,
wherein at least one of the first sensor element or the second sensor element comprises a gradiometric sensor system configured to sense a gradient of one of the first, second, or third magnetic field components.

8. The position sensor of claim 1 , and further comprising a shielding, wherein the sensor die is arranged between the shielding and the magnetic multipole.

9. A magnetic multipole comprising:
an alternating sequence of magnetic south and north poles arranged along a first direction arranged such that a magnetic field generated by a magnetic multipole at a first region has a first component, a second component, and a third component, wherein the first, second, and third components are mutually perpendicular at the first region, wherein the magnetic multipole is arranged along an expected sensor track such that the first component has an amplitude that is not uniform along the sensor track, wherein the second component has another amplitude that is uniform along the sensor track, and wherein the sensor track circle is a circle centered to an axis of a rotation.

10. The magnetic multipole of claim 9 , and further comprising a substrate, wherein the alternating sequence is arranged on the substrate.

11. The magnetic multipole of claim 9 , wherein the magnetic multipole comprises a thick portion and a thin portion.

12. The magnetic multipole of claim 9 , wherein the magnetic multipole comprises a non-toroidal geometry.

13. The magnetic multipole of claim 12 , wherein the magnetic multipole comprises a discontinuity.

14. A method of determining a position of a member that is movable in a first direction, the method comprising:
arranging a magnetic multipole along the first direction, the magnetic multipole comprising a plurality of magnetic poles having alternating polarity;
arranging at least two magnetic sensor elements at a first region proximate to the magnetic multipole and spaced apart from the magnetic multipole in a second direction, wherein the second direction is perpendicular to the first direction;
sensing a first magnetic field component of a magnetic field of the magnetic multipole along a third direction, wherein the third direction is perpendicular to both the first and second directions at the first region to generate a first signal;
sensing a second magnetic field component of the magnetic field of the magnetic multipole along a fourth direction that is perpendicular to the third direction at the first region to provide a second signal; and
combining first and second signals in order to provide a global position of the member, wherein the combining comprises cancelling out common multiplicative factors in the first and second signals.

15. The method of claim 14 , and further comprising sensing a gradient of one of the first, second, or third magnetic field components.

16. The method of claim 14 , wherein:
a first magnetic field strength of the magnetic multipole is a sinusoidal function of the position and has a first amplitude that is a strong function of the position; and
a second magnetic field strength of the magnetic multipole is a sinusoidal function of the position, and has a second amplitude that is either not a function or only a weaker function of the position relative to the first amplitude.

17. The method of claim 14 , and further comprising sensing a third magnetic field strength of the magnetic multipole corresponding to a third magnetic field perpendicular to the first direction at the first region, and determining a local position based upon the third magnetic field strength.

Assignees

• Infineon Technologies Ag

Inventors

• Ausserlechner Udo

Classifications

• G01P3/38

  using photographic means · CPC title

• G01D5/2454 Primary

  Encoders incorporating incremental and absolute signals · CPC title

• G01D2205/73

  Targets mounted eccentrically with respect to the axis of rotation · CPC title

• G01D2205/80

  Manufacturing details of magnetic targets for magnetic encoders · CPC title

• G01D11/245

  Housings for sensors · CPC title