Magnetometer

• US 8,525,514 B2
• Filed: 03/19/2010
• Issued: 09/03/2013
• Est. Priority Date: 03/19/2010
• Status: Active Grant

• Current Assignee: Memsic Semiconductor (Wuxi) Co., Ltd. (MZ Investment Holdings Ltd.)
• Original Assignee: Memsic Incorporated (MZ Investment Holdings Ltd.)
• Inventors: Cai, Yongyao, Marcelino, Jerome S., Zhao, Yang, Laich, Mark, Liu, Haidong, Li, Zongya
• Primary Examiner(s): Hollington, Jermele M
• Application Number:
  US12/727,616
• Publication Number:
  US 20110227569A1
• Time in Patent Office: 1,264 Days
• Field of Search: None
• US Class Current: 324/252
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G01R 33/096 anisotropic magnetoresistance sensors
• CPC Class Codes: G01R 33/18 Measuring magnetostrictive properties

Abstract

A magnetometer with only a SET operation for initiating a magnetic orientation within a magnetic field sensor based on anisotropic magnetoresistive (AMR) technology. Within the magnetometer, the relative orientations of the respective X, Y and Z axes detectors are maintained by a package in which all detectors are mounted on a single assembly with the Z axis sensor displaced and held orthogonal to the other two sensors by potting material. Shorting bars on respective barber pole structures are provided with a geometry that allows for closer placement of adjacent barber poles to one another. The barber pole structures are deposited in a nested orientation which provides for balanced resistance legs in a Wheatstone bridge construction.

Claims

1. A method of operating an electronic magnetic field measuring device comprising a plurality of anisotropic magnetoresistive (AMR) sensors, the method comprising:

realigning a respective magnetic domain orientation of each AMR sensor in only one direction;

subsequent to the realigning of the respective magnetic domain orientation of each AMR sensor, detecting an output signal from the plurality of AMR sensors, the output signal being representative of a local magnetic field; and

implementing a next realignment step a predetermined amount of time after the prior realignment step.

4. The method of claim 1, wherein the realigning step comprises:

passing a first current in a first direction through a first conductor positioned near the plurality of AMR sensors,

wherein a first magnitude and a first duration of the first current are chosen to sufficiently realign the magnetic domain orientation of each AMR sensor.

5. The method of claim 4, further comprising:

orienting the first direction of the first current to pass each AMR sensor substantially perpendicular relative to a longitudinal direction of each respective AMR sensor.

2. A method of operating an electronic magnetic field measuring device comprising a plurality of anisotropic magnetoresistive (AMR) sensors, the method comprising:

realigning a respective magnetic domain orientation of each AMR sensor in only one direction;

subsequent to the realigning of the respective magnetic domain orientation of each AMR sensor, detecting an output signal from the plurality of AMR sensors, the output signal being representative of a local magnetic field;

detecting a maximum value Vmax for the output signal since last realigning the magnetic domain orientations;

detecting a minimum value Vmin for the output signal since last realigning the magnetic domain orientations; and

comparing (Vmax+Vmin)/2 to a predetermined value PV to determine whether or not the realigning step should be repeated.

3. The method of claim 2, wherein comparing further comprises:

implementing a next realignment step if (Vmax+Vmin)/2 is greater than the predetermined value PV.

6. The method of claim 2, wherein the realigning step comprises:

passing a first current in a first direction through a first conductor positioned near the plurality of AMR sensors,

wherein a first magnitude and a first duration of the first current are chosen to sufficiently realign the magnetic domain orientation of each AMR sensor.

7. The method of claim 6, further comprising:

orienting the first direction of the first current to pass each AMR sensor substantially perpendicular relative to a longitudinal direction of each respective AMR sensor.