Systems and methods for a magnet with uniform magnetic flux

Patent metadata

Field	Value
Publication number	US-9583247-B2
Application number	US-201414287469-A
Country	US
Kind code	B2
Filing date	May 27, 2014
Priority date	May 27, 2014
Publication date	Feb 28, 2017
Grant date	Feb 28, 2017

Abstract

A magnet includes a magnetic body having a length and width. The body has a first notch in one side and extending along at least a portion of the length of the body, and a second notch in an opposite side of the body extending along at least a portion of the length of the body. A magnetic field produced by the body has a substantially uniform magnetic flux along at least a portion of the length of the body. A system for detecting a target includes one or more magnetic field sensing elements positioned within the portion of the magnetic field having substantially uniform flux.

First claim

What is claimed is:

1. A magnetic field sensor comprising:
a magnet comprising:
a magnetic body having a length and width;
a first triangular notch in a first side of the body and extending along a portion of the length of the body; and
a second triangular notch in an opposite side of the body extending along portion of the length of the body, wherein a length of the first and second triangular notch is less than the length of the body and a magnetic field produced by the body has a substantially uniform magnetic flux along at least a portion of the length of the body; and

three magnetic field sensing elements arranged in a linear array positioned such that each of the three magnetic field sensing elements is positioned within the area of substantially uniform magnetic flux.

2. The magnetic field sensor of claim 1 wherein the first and second notches are centered along the length of the body.

3. The magnetic field sensor of claim 1 wherein the body has a magnetic orientation perpendicular to a plane defined by the length and width of the body.

4. An apparatus comprising:
a magnet comprising:
a magnetic body having a length and width;
a first triangular notch in a side of the body and extending along at least a portion of the length of the body; and
a second triangular notch in an opposite side of the body extending along at least a portion of the length of the body, wherein a length of the first triangular notch and a length of the second triangular notch are less than the length of the body and a magnetic field produced by the body has a substantially uniform magnetic flux along at least a portion of the length of the body; and

one or more magnetic field sensing elements positioned within the substantially uniform magnetic flux.

5. The apparatus of claim 4 wherein at least one of the magnetic field sensing elements is a Hall Effect element.

6. The apparatus of claim 4 wherein at least one of the magnetic field sensing elements is a magnetoresistive element.

7. The apparatus of claim 6 wherein the magnetoresistive element is selected from the list consisting of: an Indium Antimonide element, a giant magnetoresistance (GMR) element, an anisotropic magnetoresistance element (AMR), a tunneling magnetoresistance (TMR) element, a magnetic tunnel junction (MTJ), a spin-valve element, and a combination thereof.

8. A system comprising:
a magnet having a shaped body; and
one or more substrates supporting one or more magnetic field sensing elements arranged in a substantially linear array, wherein the one or more magnetic field sensing elements is positioned within the substantially uniform flux of the magnetic field;
wherein the shaped body comprises:
a first triangular notch in a side of the body and extending along a portion of the length of the body; and
a second triangular notch in an opposite side of the body extending along a portion of the length of the body, wherein a length of the first triangular notch and a length of the second triangular notch are less than the length of the body and a magnetic field produced by the body has a substantially uniform magnetic flux along at least a portion of the length of the body.

9. The system of claim 8 further comprising an integrated circuit package containing the one or more substrates, wherein the magnet is coupled to an outside surface of the integrated circuit package.

10. The system of claim 8 further comprising an integrated circuit package containing the one or more substrates, wherein the magnet is positioned within the integrated circuit package.

11. The system of claim 8 wherein the first and second notches are centered along the length of the body.

12. The system of claim 8 wherein the magnet has a magnetic orientation substantially perpendicular to the length and width of the magnetic body.

13. The system of claim 8 wherein the first and second notches have rounded interior corners.

14. The system of claim 8 wherein the one or more magnetic field sensing elements produce respective magnetic field signals, and the system produces at least one output signal representing a combination of signals produced by adjacent magnetic field sensing elements.

15. The system of claim 14 further comprising a processor coupled to receive the output signal and determine proximity, speed, direction or a combination thereof, of a target sensed by the magnetic field sensing elements.

Assignees

• Allegro Microsystems Llc

Inventors

• David Paul A
• Metivier Ryan

Classifications

• H01F7/0278 Primary

  for generating uniform fields, focusing, deflecting electrically charged particles (for magnetic separation by Lorentz force B03C1/023; specially adapted for NMR applications G01R33/383) · CPC title

• G01D5/145

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

• H01F7/06 Primary

  Electromagnets; Actuators including electromagnets {(electric coils H01F5/00; devices for holding workpieces using electric force B23Q3/15; load-engaging elements for lifting articles electromagnetically B66C1/06; electromagnetic couplings F16D27/00; magnetic brakes F16D63/002; electromagnetically operated valves F16K11/24, F16K31/00; analysing materials by magnetic means G01N27/72, G01N27/80; electromagnets for winding mechanical clocks G04C1/02; electromagnetic relays H01H51/00; windings for salient poles of dynamo-electric machines H02K3/18; electromagnets for telegraphic communication H04L; for arc lamps H05B31/28)} · CPC title

• G01D5/24438

  Special design of the sensing element or scale · CPC title

• G01D2205/40

  Position sensors comprising arrangements for concentrating or redirecting magnetic flux · CPC title