Differential type magnetic sensor

Patent metadata

Field	Value
Publication number	US-10509080-B2
Application number	US-201615561744-A
Country	US
Kind code	B2
Filing date	Feb 23, 2016
Priority date	Mar 27, 2015
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

(Subject)
To provide a differential magnetic sensor capable of accurate magnetic detection of a local weak magnetic field even when there is a difference in detection sensitivity of a plurality of magnetic sensors used as a differential type magnetic sensor.
(Means for solving)
The differential type magnetic sensor comprises a driving circuit 2 for outputting driving currents, two magnetic detecting means E 10 , E 20 including two magneto-impedance elements comprising two magneto-sensitive bodies which are disposed at two distant points and wherein the magnetic field signal voltages are generated in response to two external magnetic fields intensities around the two magneto-sensitive bodies to which the driving currents are applied and a differential operating means 5 for operating a difference signal voltage between the two magnetic field signal voltages output from the magnetic detecting means and for outputting the difference signal voltage between the two external magnetic field intensities, and further comprises a signal adjusting means which is interposed between the driving circuit 2 and the differential operating means and adjust the two magnetic field signal voltages output based on the two magneto-sensitive bodies having different detection sensitivities such that the detection sensitivities of the two magnetic detection means are considered to be roughly the same as each other.

First claim

What is claimed is:

1. A differential type magnetic sensor comprising a driving means for outputting driving currents,
two magnetic detecting means including two magneto-impedance elements comprising two magneto-sensitive bodies which are disposed at two distant points and wherein two magnetic field signal voltages are generated in response to two external magnetic fields intensities around said two magneto-sensitive bodies to which the driving currents are applied and
a differential operating means for operating a difference signal voltage between the two magnetic field signal voltages output from said magnetic detecting means and for outputting the difference signal between the two external magnetic field intensities, and
further comprising a signal adjusting means which is interposed between said driving means and said differential operating means and adjusts the output signals of said two magnetic detecting means in response to the different detection sensitivities of two magneto-impedance elements in order that said two magnetic detecting means including said two magneto-impedance elements having different detection sensitivities output the two magnetic field signal voltages of same level in case of same intensities on the two external magnetic field intensities around said two magneto-sensitive bodies, and wherein
said differential type magnetic sensor is configured that a local weaker magnetic field than a background magnetic field component is detected by adjusting the two magnetic field signal voltages such that the detection sensitivities of the magnetic detecting means are regarded to be roughly the same as each other and canceling the background magnetic field components common to the two points.

2. The differential type magnetic sensor according to claim 1 , wherein
said signal adjusting means is configured to adjust the driving current supplied from said driving means in response to a difference between the detection sensitivities on said magneto-sensitive bodies constituting said two magneto-impedance elements.

3. The differential type magnetic sensor according to claim 1 , wherein
said signal adjusting means is configured to adjust gains of signal processing means, which connect to said two magneto-impedance elements and constitute said magnetic detecting means, in response to a difference between the detection sensitivities on said magneto-sensitive bodies constituting said two magneto-impedance elements.

Assignees

• Aichi Steel Corp

Inventors

• Kawano Takeshi
• Aoyama Hitoshi
• Yamamoto Michiharu
• Arakawa Hideo

Classifications

• G01R33/06 Primary

  using galvano-magnetic devices · CPC title

• H01L43/02

  Electricity · mapped topic

• G01R33/063 Primary

  Magneto-impedance sensors; Nanocristallin sensors · CPC title

• G01R33/0041

  using feed-back or modulation techniques · CPC title

• G01R33/0029

  Treating the measured signals, e.g. removing offset or noise · CPC title