TARGETS FOR COIL ACTUATED POSITION SENSORS

• US 20180340988A1
• Filed: 05/26/2017
• Published: 11/29/2018
• Est. Priority Date: 05/26/2017
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission), Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission), Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Latham, Alexander, Fermon, Claude, Monreal, Gerardo A., Milesi, Alejandro Gabriel
• Granted Patent: US 10,641,842 B2
• Time in Patent Office: Days
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01D 5/2013 by a movable ferromagnetic element, e.g. a core G01D5/2033 takes precedence
• CPC Class Codes: G01R 33/0005 Geometrical arrangement of magnetic sensor elements; Apparatus combining different magnetic sensor types G01R33/0206 takes precedence
• CPC Class Codes: G01R 33/0011 comprising means, e.g. flux concentrators, flux guides, for guiding or concentrating the magnetic flux, e.g. to the magnetic sensor
• CPC Class Codes: G01R 33/0017 Means for compensating offset magnetic fields or the magnetic flux to be measured; Means for generating calibration magnetic fields
• CPC Class Codes: G01R 33/0094 Sensor arrays
• CPC Class Codes: G01R 33/025 Compensating stray fields G01R33/0017 takes precedence
• CPC Class Codes: H01F 5/04 Arrangements of electric connections to coils, e.g. leads

Abstract

An apparatus comprises a conductive material having varying thickness along its length, the varying thickness providing varying response along a length of the conductive material to a magnetic field having a non-zero frequency; wherein the magnetic field produces an eddy current in the conductive material which generates a reflected magnetic field, wherein the varying response causes the reflected magnetic field to vary in strength along the length of the conductive material. The apparatus may include one or more reference portions of conductive material.

Claims

1. An apparatus comprising:

a conductive material having varying thickness along its length, the varying thickness providing varying response along a length of the conductive material to a magnetic field having a non-zero frequency;

wherein the magnetic field produces an eddy current in the conductive material which generates a reflected magnetic field, wherein the varying response causes the reflected magnetic field to vary in strength along the length of the conductive material.

2. The apparatus of claim 1 further comprising a low-conductivity material physically coupled to the conductive material.

3. The apparatus of claim 1 wherein the varying response is based at least in part on a material thickness of the conductive material.

4. The apparatus of claim 1 wherein the varying response is due to a distance between the conductive material and a source of the magnetic field.

5. The apparatus of claim 1 wherein the apparatus comprises a rod.

6. The apparatus of claim 5 wherein the conductive material has a thickness that varies along a length of the rod.

7. The apparatus of claim 6 wherein the thickness of the high conductivity varies substantially linearly along the length of the rod.

8. The apparatus of claim 5 wherein the conductive material comprises wells positioned along the length of the rod.

9. The apparatus of claim 8 wherein the wells are connected by a relatively thin portion of conductive material.

10. The apparatus of claim 1 wherein the apparatus comprises a cylinder.

11. The apparatus of claim 10 wherein the cylinder has a thickness that varies as a function of angle and varies in the radial or zeta dimension.

12. The apparatus of claim 10 wherein the conductive material comprises wells positioned in a circle around the cylinder.

13. The apparatus of claim 12 further comprising two or more circular rows of wells each arranged in a circle around the cylinder.

14. A system comprising:

one or more magnetic field sensing elements;

a coil configured to produce a magnetic field having a non-zero frequency; and

a target comprising;

a conductive material having varying response to the magnetic field along a length of the conductive material;

wherein the magnetic field produces one or more eddy currents in the conductive material which generate a reflected magnetic field that varies in strength along the length of the conductive material.

15. The system of claim 14 wherein the target comprises a rod.

16. The system of claim 15 wherein a thickness of the conductive material varies along a length of the rod.

17. The system of claim 14 wherein the target comprises a cylinder.

18. The system of claim 17 wherein a thickness of the conductive material varies with an angle of the cylinder.

19. The system of claim 14 wherein the conductive material comprises a spiral inclined plane positioned so that one portion of the conductive material is closer to the coil than another portion of the conductive material.

20. The system of claim 14 wherein the one or more magnetic field sensors are arranged in a grid.

21. The system of claim 14 wherein the target comprises a reference portion of conductive material.

22. The system of claim 14 wherein the coil is configured to produce a second magnetic field having a second non-zero frequency.

23. An apparatus comprising:

a first portion of conductive material having varying response to a generated magnetic field along a length of the conductive material, wherein the first portion of conductive material produces a varying eddy current and a varying reflected magnetic field, in response to the generated magnetic field; and

one or more reference portions of conductive material having a relatively invariable response to the generated magnetic field, wherein the reference portion of conductive material produces a relatively invariable eddy current and a relatively invariable reflected magnetic field in response to the generated magnetic field.

24. The apparatus of claim 23 wherein the first portion of conductive material comprises a varying thickness along a length of the first portion of conductive material.

25. The apparatus of claim 23 wherein the first portion of conductive material comprises a varying distance along a length of the first portion of conductive material, wherein the distance varies as function of the length of the first portion of conductive material.

26. The apparatus of claim 25 wherein the first portion of conductive material comprises an inclined plane.

27. The apparatus of claim 26 wherein the inclined plane is a spiral inclined plane.