Packages for coil actuated position sensors

• US 10,649,042 B2
• Filed: 04/25/2019
• Issued: 05/12/2020
• Est. Priority Date: 05/26/2017
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Latham, Alexander, Doogue, Michael C., Boudreau, Jason
• Primary Examiner(s): Shah, Neel D
• Application Number:
  US16/394,338
• Publication Number:
  US 20190250220A1
• Time in Patent Office: 383 Days
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01B 7/023 for measuring distance between sensor and object G01B7/082 and G01B7/102 take precedence
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: G01N 27/90 using eddy currents
• CPC Class Codes: G01P 3/49 using eddy currents
• 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 33/0029 Treating the measured signals, e.g. removing offset or noise
• CPC Class Codes: G01R 33/0094 Sensor arrays
• CPC Class Codes: G01R 33/025 Compensating stray fields G01R33/0017 takes precedence
• CPC Class Codes: G01R 33/032 using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
• CPC Class Codes: G01R 33/1284 Spin resolved measurements; Influencing spins during measurements, e.g. in spintronics devices G01R33/093 takes precedence; semiconductor devices using spin polarized carriers H01L29/66984
• CPC Class Codes: H01F 2027/348 Preventing eddy currents
• CPC Class Codes: H01F 5/003 Printed circuit coils

Abstract

An apparatus comprises a first substrate and two coils supported by the first substrate and arranged next to each other, the coils configured to each generate a magnetic field which produces eddy currents in and a reflected magnetic field from a conductive target, the two coils arranged so their respectively generated magnetic fields substantially cancel each other in an area between the coils. One or more magnetic field sensing elements are positioned in the area between the coils and configured to detect the reflected magnetic field.

Claims

1. An apparatus comprising:

a first substrate;

two coils supported by the first substrate and arranged next to each other such that a current through each of the coils flows in the same plane, the coils configured to each generate a magnetic field which produces eddy currents in and a reflected magnetic field from a conductive target, the two coils arranged so their respectively generated magnetic fields substantially cancel each other in an area between the coils; and

one or more magnetic field sensing elements positioned in the area between the coils and configured to detect the reflected magnetic field in order to detect one or more of a position, speed, rotational angle, or direction of the conductive target.

2. The apparatus of claim 1 wherein the one or more magnetic field sensing elements comprise a bridge circuit.

3. The apparatus of claim 1 wherein the one or more magnetic field sensing elements comprise at least two pairs of magnetic field sensing elements.

4. The apparatus of claim 3 wherein a center area of the conductive target is adjacent to one of the pairs of magnetic field sensing elements and an edge of the conductive target is adjacent to another of the pairs of magnetic field sensing elements.

5. The apparatus of claim 1 further comprising a second substrate, wherein the one or more magnetic field sensing elements and/or a processing circuit are supported by the second substrate.

6. The apparatus of claim 5 wherein the second substrate is centered in the area between the coils.

7. The apparatus of claim 5 wherein the first and/or second substrates comprise one or more of:

a semiconductor material, a glass material, or a ceramic material.

8. An apparatus comprising:

a first substrate;

a conductive trace supported by the first substrate and having a first portion looped in a first direction to form a first coil and a second portion looped in a second direction to form a second coil, wherein the second direction is opposite the first direction and wherein the first and second coils are configured to each generate a magnetic field which produces eddy currents in and a reflected magnetic field from a conductive target, the two coils arranged so their respectively generated magnetic fields substantially cancel each other in an area between the coils; and

one or more magnetic field sensing elements positioned in the area between the coils and configured to detect the reflected magnetic field in order to detect one or more of a position, speed, rotational angle, or direction of the conductive target.

9. The apparatus of claim 8 wherein the one or more magnetic field sensing elements comprise a bridge circuit.

10. The apparatus of claim 8 wherein the one or more magnetic field sensing elements comprise at least two pairs of magnetic field sensing elements.

11. The apparatus of claim 10 wherein a center area of the conductive target is adjacent to one of the pairs of magnetic field sensing elements and an edge of the conductive target is adjacent to another of the pairs of magnetic field sensing elements.

12. The apparatus of claim 8 further comprising a second substrate, wherein the one or more magnetic field sensing elements and/or a processing circuit are supported by the second substrate.

13. The apparatus of claim 12 wherein the second substrate is centered in the area between the coils.

14. The apparatus of claim 12 wherein the first and/or second substrates comprise one or more of:

a semiconductor material, a glass material, or a ceramic material.

15. An apparatus comprising:

a first substrate;

two coils supported by the first substrate and arranged next to each other such that a current through each of the coils flows in opposite directions with respect to each other, the coils configured to each generate a magnetic field which produces eddy currents in and a reflected magnetic field from a conductive target, the two coils arranged so their respectively generated magnetic fields substantially cancel each other in an area between the coils; and

one or more magnetic field sensing elements positioned in the area between the coils and configured to detect the reflected magnetic field in order to detect one or more of a position, speed, rotational angle, or direction of the conductive target.

16. The apparatus of claim 15 wherein the one or more magnetic field sensing elements comprise a bridge circuit.

17. The apparatus of claim 15 wherein the one or more magnetic field sensing elements comprise at least two pairs of magnetic field sensing elements.

18. The apparatus of claim 17 wherein a center area of the conductive target is adjacent to one of the pairs of magnetic field sensing elements and an edge of the conductive target is adjacent to another of the pairs of magnetic field sensing elements.

19. The apparatus of claim 15 further comprising a second substrate, wherein the one or more magnetic field sensing elements and/or a processing circuit are supported by the second substrate.

20. The apparatus of claim 19 wherein the second substrate is centered in the area between the coils.

21. The apparatus of claim 19 wherein the first and/or second substrates comprise one or more of:

a semiconductor material, a glass material, or a ceramic material.