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US 2017/0314907 A1Published application
Arrangements For Magnetic Field Sensors That Act As Tooth Detectors
AssigneeAllegro MicroSystems, LLC
InventorsWilliam P. Taylor, P. Karl Scheller, Paul A. David
Life of this patent
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Abstract
A variety of magnetic field sensor arrangements provide so-called “tooth detectors” using a simple low-cost magnet.
Claims33
A magnetic field sensor for sensing motion of a ferromagnetic object, comprising:
- a substrate, comprising:
- a first major surface, wherein a first dimension across the first major surface of the substrate defines a width dimension of the substrate and a second dimension across the first major surface of the substrate perpendicular to the width dimension defines a length dimension of the substrate;
- first and second substrate edges at ends of the width dimension of the substrate;
- and
- a second major surface parallel to the first major surface, wherein the magnetic field sensor further comprises:
- a magnet, comprising:
- a first major surface proximate to the substrate and substantially parallel to the first major surface of the substrate, wherein a first dimension across the first major surface of the magnet defines a width dimension of the magnet and a second dimension across the first major surface of the magnet perpendicular to the width dimension defines a length dimension of the magnet;
- a second major surface distal from the substrate and parallel to the first major surface of the magnet;
- and
- a magnet axis perpendicular to the first and second major surfaces of the magnet and centered within the width dimension and length dimension of the magnet, wherein the magnetic field sensor further comprises:
- a first magnetic field sensing element disposed upon the first major surface or the second major surface of the substrate and configured to generate a first magnetic field signal, wherein the first magnetic field sensing element comprises a center;
- and
- a second magnetic field sensing element disposed upon the first major surface or the second major surface of the substrate and configured to generate a second magnetic field signal, wherein the second magnetic field sensing element comprises a center, wherein the center of the first magnetic field sensing element and the center of the second magnetic field sensing element are the same distance from the first major surface of the magnet, wherein a line passing through the first and second magnetic field sensing elements intersects the ferromagnetic object, wherein the line passing through the first and second magnetic field sensing elements is parallel to the width dimension of the substrate and parallel to the width dimension of the magnet, wherein the center of the first magnetic field sensing element and the center of the second magnetic field sensing element are positioned upon the substrate beyond first and second respective ends of the width dimension of the magnet such that first and second lines passing through the first and second centers, respectively, of the first and second magnetic field sensing elements and perpendicular to the first major surface of the substrate, do not intersect the magnet, wherein the second magnetic field sensing element is substantially farther from the ferromagnetic object than the first magnetic field sensing element, resulting in the first magnetic field sensing element being substantially more responsive to the motion of the ferromagnetic object than the second magnetic field sensing element, wherein the magnet is offset from the line passing through the first and second magnetic field sensing elements in a direction perpendicular to the line passing through the first and second magnetic field sensing elements, and wherein the line passing through the first and second magnetic field sensing elements is perpendicular to the magnet axis.
10 more elements
A magnetic field sensor for sensing motion of a ferromagnetic object, comprising:
- a substrate, comprising:
- a first major surface, wherein a first dimension across the first major surface of the substrate defines a width dimension of the substrate and a second dimension across the first major surface of the substrate perpendicular to the width dimension defines a length dimension of the substrate;
- first and second substrate edges at ends of the width dimension of the substrate;
- and
- a second major surface parallel to the first major surface, wherein the magnetic field sensor further comprises:
- a magnet, comprising:
- a first major surface proximate to the substrate and substantially parallel to the first major surface of the substrate, wherein a first dimension across the first major surface of the magnet defines a width dimension of the magnet and a second dimension across the first major surface of the magnet perpendicular to the width dimension defines a length dimension of the magnet;
- a second major surface distal from the substrate and parallel to the first major surface of the magnet;
- and
- a magnet axis perpendicular to the first and second major surfaces of the magnet and centered within the width dimension and length dimension of the magnet, wherein the magnetic field sensor further comprises:
- a first magnetic field sensing element disposed upon the first major surface or the second major surface of the substrate and configured to generate a first magnetic field signal, wherein the first magnetic field sensing element comprises a center;
- and
- a second magnetic field sensing element disposed upon the first major surface or the second major surface of the substrate and configured to generate a second magnetic field signal, wherein the second magnetic field sensing element comprises a center, wherein the center of the first magnetic field sensing element and the center of the second magnetic field sensing element are the same distance from the first major surface of the magnet, wherein a line passing through the first and second magnetic field sensing elements intersects the ferromagnetic object, wherein the line passing through the first and second magnetic field sensing elements is parallel to the width dimension of the substrate and parallel to the width dimension of the magnet, wherein the second magnetic field sensing element is substantially farther from the ferromagnetic object than the first magnetic field sensing element, resulting in the first magnetic field sensing element being substantially more responsive to the motion of the ferromagnetic object than the second magnetic field sensing element, wherein the magnet is offset from the line passing through the first and second magnetic field sensing elements in a direction perpendicular to the line passing through the first and second magnetic field sensing elements, and wherein the line passing through the first and second magnetic field sensing elements is perpendicular to the magnet axis, wherein the first magnetic field sensing element is selected from among a plurality of magnetic field sensing elements disposed upon the first major surface or the second major surface of the substrate, the selection of the first magnetic field sensing element based upon a desired accuracy characteristic of the magnetic field sensor, and other ones of the plurality of magnetic field sensing elements are inactive.
10 more elements
A magnetic field sensor for sensing motion of a ferromagnetic object, comprising:
- a substrate, comprising:
- a first major surface, wherein a first dimension across the first major surface of the substrate defines a width dimension of the substrate and a second dimension across the first major surface of the substrate perpendicular to the width dimension defines a length dimension of the substrate;
- first and second substrate edges at ends of the width dimension of the substrate;
- and
- a second major surface parallel to the first major surface, wherein the magnetic field sensor further comprises:
- a magnet, comprising:
- a first major surface proximate to the substrate and substantially parallel to the first major surface of the substrate, wherein a first dimension across the first major surface of the magnet defines a width dimension of the magnet and a second dimension across the first major surface of the magnet perpendicular to the width dimension defines a length dimension of the magnet;
- a second major surface distal from the substrate and parallel to the first major surface of the magnet;
- and
- a magnet axis perpendicular to the first and second major surfaces of the magnet and centered within the width dimension and length dimension of the magnet, wherein the magnetic field sensor further comprises:
- a first magnetic field sensing element disposed upon the first major surface or the second major surface of the substrate and configured to generate a first magnetic field signal, wherein the first magnetic field sensing element comprises a center;
- and
- a second magnetic field sensing element disposed upon the first major surface or the second major surface of the substrate and configured to generate a second magnetic field signal, wherein the second magnetic field sensing element comprises a center, wherein the center of the first magnetic field sensing element and the center of the second magnetic field sensing element are the same distance from the first major surface of the magnet, wherein a line passing through the first and second magnetic field sensing elements intersects the ferromagnetic object, wherein the line passing through the first and second magnetic field sensing elements is parallel to the width dimension of the substrate and parallel to the width dimension of the magnet, wherein the second magnetic field sensing element is substantially farther from the ferromagnetic object than the first magnetic field sensing element, resulting in the first magnetic field sensing element being substantially more responsive to the motion of the ferromagnetic object than the second magnetic field sensing element, wherein the magnet is offset from the line passing through the first and second magnetic field sensing elements in a direction perpendicular to the line passing through the first and second magnetic field sensing elements, and wherein the line passing through the first and second magnetic field sensing elements is perpendicular to the magnet axis, wherein the magnetic field sensor is operable to generate an output signal indicative of a tooth detector and not an edge detector.
10 more elements
Dependencies are inferred from the claim text.