Magnetic Field Sensor Providing a Movement Detector

Patent metadata

Field	Value
Publication number	US-2016123771-A1
Application number	US-201414529669-A
Country	US
Kind code	A1
Filing date	Oct 31, 2014
Priority date	Oct 31, 2014
Publication date	May 5, 2016
Grant date	—

Abstract

A magnetic field sensor has a plurality of magnetic field sensing elements and operates as a motion detector for sensing a rotation or other movement of a target object.

First claim

What is claimed is:

1 . A magnetic field sensor for measuring movement of a target object, the movement in an x-z plane within x-y-z Cartesian coordinates with x, y, and z orthogonal axes, a tangent to a direction of movement of a surface of the target object proximate to the magnetic field sensor substantially parallel to the x axis, the magnetic field sensor comprising:
a substrate having a major planar surface within about twenty degrees of parallel to the x-z plane; and a plurality of magnetic field sensing elements disposed upon the major planar surface of the substrate, each one of the plurality of magnetic field sensing elements having a major response axis substantially parallel to the major planar surface of the substrate, and the plurality of magnetic field sensing elements is configured to generate a respective plurality of magnetic field signals.

2 . The magnetic field sensor of claim 1 , wherein the plurality of magnetic field sensing elements comprises a plurality of magnetoresistance elements.

3 . The magnetic field sensor of claim 1 , further comprising:
an electronic circuit disposed upon the substrate and coupled to the plurality of magnetic field sensing elements, the electronic circuit comprising: a non-volatile memory device operable to store a value indicative of a measured operational characteristic of the magnetic field sensor.

4 . The magnetic field sensor of claim 3 , wherein the stored value is stored during a first time period, and wherein the stored value is recalled and used during a second different time period after the first time period.

5 . The magnetic field sensor of claim 1 , further comprising:
an electronic circuit disposed upon the substrate and coupled to the plurality of magnetic field sensing elements, the electronic circuit comprising: an output protocol module operable to use the plurality of magnetic field signals to determine a direction of movement of the target object.

6 . The magnetic field sensor of claim 1 , further comprising:
a magnet disposed proximate to the substrate, the magnet having at least two poles to generate a magnetic field substantially parallel to the major planar surface of the substrate.

7 . The magnetic field sensor of claim 6 , wherein the major planar surface of the substrate overlaps the target object such that a line perpendicular to the major planar surface of the substrate intersects the target object.

8 . The magnetic field sensor of claim 1 , wherein the target object comprises a ring magnet having a plurality of alternating north and south poles, the target object to generate a magnetic field substantially parallel to the major planar surface of the substrate.

9 . The magnetic field sensor of claim 8 , wherein the major planar surface of the substrate overlaps the target object such that a line perpendicular to the major planar surface of the substrate intersects the target object.

10 . The magnetic field sensor of claim 1 , wherein the plurality of magnetic field sensing elements is arranged in a line within about twenty degrees of parallel to the tangent to the direction of movement of the target object.

11 . The magnetic field sensor of claim 10 , wherein the plurality of magnetic field sensing elements comprises a quantity of magnetic field sensing elements in a range of two to nine magnetic field sensing elements.

12 . The magnetic field sensor of claim 10 , wherein the electronic circuit further comprises:
an output protocol module operable to use the plurality of magnetic field signals to determine a direction of movement of the target object.

13 . The magnetic field sensor of claim 10 , further comprising:
a non-volatile memory device operable to store a value indicative of a measured operational characteristic of the magnetic field sensor.

14 . The magnetic field sensor of claim 10 , wherein the plurality of magnetic field sensing elements comprises a plurality of magnetoresistance elements.

15 . The magnetic field sensor of claim 10 , wherein maximum response axes of the plurality of magnetic field sensing elements are substantially parallel to each other.

16 . The magnetic field sensor of claim 10 , further comprising:
an electronic circuit disposed upon the substrate and coupled to the plurality of magnetic field sensing elements, the electronic circuit comprising:
a plurality of analog or digital comparators configured to compare each respective one of the plurality of magnetic field signals to a threshold signal to generate a plurality of binary signals, wherein states of the plurality of binary signals are indicative of a position of the target object relative to the plurality of magnetic field sensing elements.

17 . The magnetic field sensor of claim 16 , wherein the electronic circuit further comprises:
an output protocol module operable to use the plurality of binary signals to determine a direction of movement of the target object.

18 . The magnetic field sensor of claim 16 , wherein the electronic circuit further comprises:
a non-volatile memory device operable to store a value indicative of a measured operational characteristic of the magnetic field sensor.

19 . The magnetic field sensor of claim 10 , further comprising:
an electronic circuit disposed upon the substrate and coupled to the plurality of magnetic field sensing elements, the electronic circuit operable to determine a position of the target object relative to the plurality of magnetic field sensing elements.

20 . The magnetic field sensor of claim 10 , further comprising:
an electronic circuit disposed upon the substrate and coupled to the plurality of magnetic field sensing elements, the electronic circuit comprising:
at least one analog-to digital converter operable to convert the plurality of magnetic field signals to generate a plurality of binary signals, wherein states of the plurality of binary signals are indicative of a position of the object relative to the plurality of magnetic field sensing elements.

21 . The magnetic field sensor of claim 20 , wherein the at least one analog-to-digital converter comprises a plurality of analog-to-digital converters, each one of the plurality of analog-to-digital converters coupled to a respective one of the plurality of magnetic field sensing elements.

22 . The magnetic field sensor of claim 10 , further comprising:
an electronic circuit disposed upon the substrate and coupled to the plurality of magnetic field sensing elements, the electronic circuit comprising: a processor configured to compare each respective one of the plurality of magnetic field signals to a respective threshold signal to generate a plurality of binary signals, wherein states of the plurality of binary signals are indicative of a position of the target object relative to the plurality of magnetic field sensing elements.

23 . The magnetic field sensor of claim 22 , wherein the electronic circuit further comprises:
a. threshold calculation module coupled to receive signals representative of the plurality of magnetic field signals, the threshold calculation module configured to generate a plurality of threshold values indicative of amplitudes of the plurality of magnetic field signals; a nonvolatile memory device operable to store the plurality of threshold values; and a plurality of analog or digital comparators, the memory device operable to provide the plurality of threshold values as input values to the

Assignees

• Allegro Microsystems Llc

Inventors

• David Paul A
• Taylor William P

Classifications

• G01D5/147

  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 title

• G01D5/145 Primary

  influenced by the relative movement between the Hall device and magnetic fields (see G01R33/06) · CPC title

• G01D5/2013

  by a movable ferromagnetic element, e.g. a core (G01D5/2033 takes precedence) · CPC title