Coil actuated pressure sensor and deflectable substrate

Patent metadata

Field	Value
Publication number	US-11061084-B2
Application number	US-201916295131-A
Country	US
Kind code	B2
Filing date	Mar 7, 2019
Priority date	Mar 7, 2019
Publication date	Jul 13, 2021
Grant date	Jul 13, 2021

Abstract

A pressure sensor includes a conductive substrate having a cavity which forms a thin portion that can be deformed by a pressure differential. A magnetic field sensor has at least one coil responsive to a changing coil drive signal and positioned proximate to the thin portion of the substrate that induces eddy currents in the thin portion that generate a reflected magnetic field. Magnetic field sensing elements detect the reflected magnetic field and generate a magnetic field signal. The magnetic field sensor is positioned so that deformation of the thin portion of the substrate causes a distance between the thin portion of the substrate and the magnetic field sensor to change.

First claim

The invention claimed is:

1. A pressure sensor comprising:
a substrate having a cavity and at least a portion that is conductive and that is configured to be deformed by a pressure differential across the conductive substrate; and
a magnetic field sensor comprising:
at least one coil responsive to a changing coil drive signal and positioned proximate to the portion of the substrate so that a magnetic field produced by the at least one coil induces eddy currents in the portion of the substrate that generate a reflected magnetic field; and
at least one magnetic field sensing element disposed proximate to the at least one coil and to the portion of the substrate, and configured to generate a magnetic field signal in response to the reflected magnetic field;
wherein the magnetic field sensor is positioned so that deformation of the portion of the substrate causes a distance between the portion of the substrate and the at least one magnetic field sensing element to change.

2. The pressure sensor of claim 1 wherein a strength of the reflected magnetic field is responsive to the distance between the portion of the substrate and the magnetic field sensor.

3. The pressure sensor of claim 1 wherein a value of the magnetic field signal is responsive to the distance between the portion of the substrate and the magnetic field sensor.

4. The pressure sensor of claim 1 wherein the cavity is substantially rectangular and has squared corners and/or rounded corners.

5. The pressure sensor of claim 1 wherein the conductive substrate comprises mounting posts to mount a second substrate and/or a backing plate that supports a second substrate.

6. The pressure sensor of claim 1 wherein the at least one magnetic field sensing element comprises a magnetoresistance element, a Hall effect element, or both.

7. The pressure sensor of claim 1 wherein the substrate comprises a conductive material.

8. The pressure sensor of claim 1 wherein the substrate comprises a conductive coating.

9. The pressure sensor of claim 1 wherein the changing coil drive signal is an AC drive signal.

10. The pressure sensor of claim 1 further comprising a second substrate that supports the magnetic field sensor.

11. The pressure sensor of claim 10 wherein the second substrate is a printed circuit board, the magnetic field sensor is an integrated circuit, and the printed circuit board supports the integrated circuit.

12. The pressure sensor of claim 10 further comprising a backing plate physically coupled to the conductive substrate to form one wall of the cavity, wherein the second substrate is supported by the backing plate.

13. The pressure sensor of claim 1 wherein the conductive substrate forms a pipe and the cavity is formed on an inner surface of the pipe.

14. The pressure sensor of claim 13 further comprising a second cavity formed on an outer surface of the pipe and positioned so that the cavity and the second cavity form the portion.

15. The pressure sensor of claim 13 wherein a pressure within the pipe causes the portion to deform and the distance between the portion and the magnetic field sensor to change.

16. The pressure sensor of claim 1 further comprising a second cavity, wherein the cavity and the second cavity are positioned on opposite sides of the conductive substrate, and the portion is formed between the cavity and the second cavity.

17. The pressure sensor of claim 16 wherein the second cavity is substantially rectangular in shape and has squared corners and/or rounded corners.

18. The pressure sensor of claim 16 wherein the cavity and the second cavity have substantially the same length.

19. The pressure sensor of claim 16 wherein the second cavity is a rounded hollow in the conductive substrate.

20. The pressure sensor of claim 16 wherein the second cavity has a stepped shape.

21. The pressure sensor of claim 20 wherein:
the stepped shape is symmetric;
the stepped shape forms a deep portion and a shallow portion;
the shallow portion is configured to engage a second substrate that supports the magnetic field sensor; and
the second substrate is positioned so that the magnetic field sensor is positioned in the deep portion.

22. The pressure sensor of claim 20 wherein:
the stepped shape is asymmetric;
the stepped shape forms:
a deep portion adjacent to the, deformable portion of the conductive substrate; and

and a shallow portion;
the magnetic field sensor comprises at least two magnetic field sensing elements; and
the magnetic field sensor is positioned so that a first magnetic field sensing element is positioned in the shallow portion and a second magnetic field sensing element is positioned in the deep portion.

23. The pressure sensor of claim 22 wherein the first magnetic field sensing element produces a reference signal and the second magnetic field sensing element produces the magnetic field signal.

Assignees

• Allegro Microsystems Llc

Inventors

• Cadugan Bryan
• David Paul A
• Boudreau Jason
• Taylor William P

Classifications

• G01L13/025

  using diaphragms · CPC title

• G01R33/072 Primary

  Constructional adaptation of the sensor to specific applications · CPC title

• G01L9/007 Primary

  using variations in inductance · CPC title

• G01R33/0005

  Geometrical arrangement of magnetic sensor elements; Apparatus combining different magnetic sensor types (G01R33/0206 takes precedence) · CPC title