JP3752061B2 - Magnetic field detection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for detecting an external magnetic field using an amorphous magnetic element.
[0002]
[Prior art]
As an amorphous alloy wire, an amorphous alloy wire having zero magnetostriction or negative magnetostriction has been developed, which has an outer shell portion in which magnetic domains whose spontaneous magnetization directions are opposite to each other in the circumferential direction of the wire are separated by a domain wall. Yes. For example, Co _70.5 B ₁₅ Si ₁₀ Fe _4.5 has been developed.
[0003]
The inductance voltage component in the output voltage between both ends of the wire generated when a high frequency current is applied to the zero magnetostrictive or negative magnetostrictive amorphous magnetic wire is easily increased in the circumferential direction by the circumferential magnetic flux generated in the cross section of the wire. This is due to the magnetized outer shell being magnetized in the circumferential direction, and therefore the circumferential permeability μθ also depends on the circumferential magnetization of the outer shell.
[0004]
When an external magnetic field in the wire axial direction is applied to the energized amorphous wire, a magnetic flux acting on the outer shell portion having the easily magnetizable property in the circumferential direction is obtained by combining the circumferential magnetic flux and the external magnetic flux generated by the energization. Is deviated from the circumferential direction and magnetization in the circumferential direction is less likely to occur, the circumferential permeability μθ is changed, and the inductance voltage is changed.
Further, when the frequency of the energization current is in the order of MHz, the high frequency skin effect cannot be ignored, and the skin depth δ = (2ρ / wμθ) ^1/2 (μθ is the circumferential permeability, as described above, (ρ is electrical resistivity, w is angular frequency) changes with μθ, and this μθ changes with the external magnetic field as described above, so the resistance voltage component in the output voltage across the wire also changes with the external magnetic field. .
Therefore, it is possible to detect the external magnetic field from both the inductance voltage and the resistance voltage due to the external magnetic field, that is, the fluctuation of the output voltage between both ends of the wire (hereinafter, the fluctuation of the output voltage due to the external magnetic field is referred to as the impedance effect). It has been proposed (Japanese Patent Laid-Open No. 7-181239).
[0005]
The impedance effect of the zero magnetostrictive or negative magnetostrictive amorphous alloy wire is that the magnetic domain of the outer shell portion in which the magnetic domains of the spontaneous magnetization are alternately located in the positive and negative circumferential directions is external Rotated by a circumferential AC magnetic field shifted by an angle (α °) by the magnetic field, the circumferential permeability μθ is changed by an external magnetic field, and the skin depth is changed by the circumferential permeability μθ changed by the external magnetic field Depending on the fluctuation of the angle, the difference between the positive and negative values of the deviation angle α ° does not produce a difference. Therefore, the output between the positive and negative external magnetic fields in the wire axis direction, that is, + Hex and -Hex does not produce a difference. A parameter change occurs.
For this reason, it is known to apply a bias magnetic field to obtain a linear characteristic.
[0006]
[Problems to be solved by the invention]
In the magnetic field sensor, an electrically and mechanically stable welding between the amorphous magnetic element and the electrode is indispensable.
Therefore, the welding requires advanced technology so as not to crystallize the molten amorphous alloy during cooling (to maintain the amorphous state), and welding with copper, which is a general-purpose electrode material, is extremely difficult. It is.
Therefore, the present inventors diligently searched for a material that can be welded to the amorphous alloy, and found that there are many magnetic materials that can be welded to the amorphous alloy relatively easily.
It is estimated that the reason why the welding is easy is that the magnetic material contains a large amount of Fe, Co, Cr and the like and contains many atoms in common with the atoms in the amorphous alloy composition.
[0007]
An object of the present invention is to weld an amorphous magnetic element to an electrode of a magnetic field sensor when an external magnetic field is detected using the impedance effect of the zero magnetic strain or negative magnetostrictive amorphous magnetic wire under the bias magnetic field action. It is an object of the present invention to provide a magnetic field detection method using a magnetic material that is easy to detect and capable of performing detection with sufficiently high sensitivity while maintaining good linear characteristics.
[0008]
[Means for Solving the Problems]
In the magnetic field detection method according to claim 1 of the present application, an amorphous magnetic element is welded between electrodes, a current is applied to the element of a magnetic field sensor in which a coil is disposed in the vicinity of the element, and a bias magnetic field is applied by the coil. Thus, in the method of detecting the external magnetic field from the change in the voltage across the amorphous magnetic element, a magnetic material electrode is used as the electrode of the magnetic field sensor, and the magnetization of the magnetic material electrode due to the bias magnetic field and the external magnetic field is suppressed. Further, the magnetic material electrode is magnetized with a polarity opposite to its magnetization.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of a linear magnetic field sensor used in the present invention.
In FIG. 1, 1 is an insulating substrate, for example, a glass epoxy substrate, a ceramic substrate, etc., and the dimension is 10 mm or less in both length and width. Reference numerals 2a and 2b denote a pair of bar-shaped electrodes made of a magnetic material, and the tip side is fixed to one side of the insulating substrate 1 in parallel arrangement. The rear ends of these bar electrodes 2a and 2b are drawn out of the insulating substrate 1. Reference numeral 3 denotes an amorphous magnetic wire as an amorphous magnetic element connected by welding between the tip ends 21a and 21b of the bar-like electrode, and one end portion is extended from the tip end 21a of one electrode in order to widen the detection range for localized magnetism. It may be protruded.
This amorphous magnetic wire 3 has an outer shell portion in which magnetic domains whose spontaneous magnetization directions are opposite to each other in the circumferential direction of the wire are alternately separated by a domain wall, and an amorphous alloy wire having zero magnetostriction or negative magnetostriction. Is used.
Reference numeral 4 denotes a bias magnetic field generating coil disposed in the vicinity of the amorphous magnetic element, which is disposed on the insulating substrate so that the direction of the generated magnetic field coincides with the axial direction of the amorphous magnetic element.
[0010]
FIG. 2 is a diagram for explaining a magnetic field detection method according to claim 1, where Hex represents an external magnetic field to be detected, Hb represents a magnetic field generated by a coil, and a high-frequency power source 5 is connected between the electrodes 2 a and 2 b. A high-frequency current is passed through the amorphous magnetic wire 3 and the output voltage V across the wire
Go to measure.
In FIG. 2, assuming that the electrode is non-magnetic, the magnetic field passing through the amorphous magnetic element in the axial direction may be assumed to be an external magnetic field and a coil-generated magnetic field. The fluctuation occurs in the magnetic domain of the outer shell of the amorphous magnetic wire in which the direction of spontaneous magnetization and the magnetic domain in the negative circumferential direction are alternately positioned. ) Rotating with a shifted circumferential AC magnetic field to change the circumferential magnetic permeability μθ with an external magnetic field, and changing the skin depth with the circumferential magnetic permeability μθ changed with the external magnetic field Therefore, there is no difference in the output voltage when the difference of the deviation angle α ° is only positive and negative. Therefore, when the external magnetic field is the same in magnitude and only in the positive and negative directions, the output voltage becomes zero when the bias magnetic field is zero. The difference is Does not occur and does not have linear characteristics.
[0011]
On the other hand, when the bias magnetic field Hb is applied, the output voltage value for the external magnetic field (Hb + Hex) is different from the output voltage value for the external magnetic field (Hb−Hex). The output voltage with respect to the detected external magnetic field + Hex can be made different, the polarity of the detected external magnetic field can be discriminated, and the bias magnetic field Hb can be set appropriately to achieve linear characteristics within the range of a certain external magnetic field.
[0012]
By the way, in the magnetic field detection method according to the first aspect, since the magnetic material is used for the electrode of the magnetic field sensor, the electrode is magnetized by the magnetic induction generated by the coil and the external magnetic field, and the magnetic field is based on the magnetization. H ′ is generated, and the magnetic field passing through the amorphous magnetic element becomes Hb + Hex + H ′.
However, in the invention according to claim 1, the magnetization of the magnetic material electrode is anticipated, the magnetic material electrode is previously magnetized with the opposite polarity to the magnetization, and the magnetic molecules of the magnetic material electrode are caused to generate magnetic fields by the external magnetic field and the coil generation magnetic field. It is designed not to magnetize even if it is oriented, and an external magnetic field can be detected with the same linear characteristics and sensitivity as when the electrode is a non-magnetic material without magnetization.
[0013]
As described above, according to the present invention, when a magnetic material is used for the electrode of the magnetic field sensor, the electrode is a non-magnetic material such as copper under the action of a bias magnetic field by the coil. Can detect an external magnetic field with the same linear characteristics and sensitivity.
Therefore, according to the present invention, the external magnetic field is excellent in linear characteristics and sensitivity even under harsh environments such as under vibration due to stable electrical and mechanical welding between the magnetic electrode of the magnetic field sensor and the amorphous magnetic element. Can be detected.
[0014]
As the magnetic material, in addition to those used in the examples, the following hard magnetic materials and semi-hard magnetic materials can be used.
(1) Hard magnetic material Fe, Co, Cr, Ni—Co alloy (Co 20 wt%, Ni 80 wt%), permalloy (Fe 10 wt%, Ni 90 wt%), supermalloy (Fe 50 wt%, Ni 50 wt%) ), Kovar (Co 17-18 wt%, Ni 28-29 wt%, balance Fe).
(2) Semi-hard magnetic material 17% Cr steel (C 0.7 wt%, Cr 2.5 wt%, Co 17 wt%, balance Fe), 36% Co steel (C 0.7 wt%, Cr 4 wt%, Co 36 wt%) , Balance Fe), bicalloy alloy (V10-20 wt%, Cr10-20 wt%, Co52 wt%, balance Fe), P-6 alloy (V4 wt%, Co45 wt%, Ni6 wt%, balance Fe) Fe -Ni-Al alloy (Al 9 wt%, Co trace, Cu trace, Ni 14-18 wt%), Fe-Mn-Ti alloy (Ti 3 wt%, Mn 12-13 wt%, balance Fe), Fe-Mn alloy (Mn12 .5 wt%, balance Fe), Fe—Mn—Cr—N alloy (N slightly, Cr 7 wt%, Mn 12 wt%, Co slightly, Mo slightly, balance Fe), maraging steel (Co 0.01 wt%, Al 0.16 weight %, Si 0.1% by weight, P 0.007% by weight, Ti 19.7% by weight, Mn 0.18% by weight, Co 12.15% by weight, Ni 19.74% by weight, Mo 3.13% by weight, balance Fe), Fe- Cr—Co alloy (Si 1.5 wt%, Cr 25 to 35 wt%, Co 10 wt%, balance Fe), Fe—Cr—Mo alloy (Co 12 wt%, Mo 8 wt%, balance Fe), Fe—Cr—Ni— Cr alloy (Cr 6-9 wt%, Co 22 wt%, Ni 14-11, balance Fe), carbon steel (C 0.5 wt%, balance Fe), FNC alloy (Ni 16-18 wt%, Cu 6 wt%, balance Fe) Fe-Mn-Co alloy (Mn 5-10 wt%, Co 13-20 wt%, balance Fe), Fe-Ni-Al-Ti alloy (Al 3-4.5 wt%, Ti slightly, Ni 14-23 wt%, Remaining Fe) Fe—Co—Ni—Cr—Cu (Co 20 to 25 wt%, Ni 12 wt%, Cr 7 to 5 wt%, Cu 3 wt%, balance Fe), Licalloy (Nb 3.1 wt%, balance Fe), Fe—Co— Cu—V alloy (V 0.9 wt%, Co 16.3 wt%, Cu 20.9 wt%, balance Fe), Co—Cr steel (C 0.80 to 0.84 wt%, Cr 4.4 to 4.6 wt%) %, Mn 0.5 to 0.6 wt%, Co 14 to 15 wt%, balance Fe), Co—Fe—Au alloy (Fe 12 wt%, Au 6 wt%, balance Co), Co—Fe—Ti alloy (Ti 3 wt%) %, Fe 12 wt%, balance Co), Co—Fe—Be alloy (Be 1.3 wt%, Fe 10.2 wt%, balance Co), Nibucolloy (Fe 12 wt%, Nb 3 wt%, balance Co), Fe—Cu Alloy (Fe 60% by weight, balance u), Fe-Cu-Mn alloy (Mn 1.7 wt%, FE80 wt%, balance Cu) or the like.
[0015]
As the amorphous magnetic element, in addition to the amorphous magnetic wire, an amorphous magnetic thin film (thickness 0.001 to 5 μm) formed on a substrate by vacuum deposition, ion sputtering, or the like can be used.
The electrode can be formed by sticking the foil, etching, spraying, sputtering, vapor deposition, plating, or the like of the metal foil of the metal foil laminated insulating substrate.
[0016]
As a magnetic field detection device used in the present invention, a Colpitts oscillation circuit having the magnetic field sensor as an inductive element is assembled, and a demodulation circuit for demodulating the amplitude modulation of the oscillation circuit by an external magnetic field is connected. It is possible to use the one that extracts only the inductance voltage component having a sharp rise compared to the resistance voltage component through −.
[0017]
【Example】
The magnetic field sensors used are as follows.
In FIG. 2, a 1.0 mm thick ceramic plate was used for the insulating substrate 1 and a Co _70.5 B ₁₅ Si ₁₀ Fe _4.5 amorphous wire having an outer diameter of 50 μm was used for the amorphous magnetic wire. The dimensions of each part of the electrodes 2a and 2b are as follows: a = 5.0 mm, b = 6.0 mm, c = 10.30 mm, d = 0.5 mm, e = 0.3 mm, f = 0.3 mm, g = 0.5 mm H = 2.3 mm. A tube with an outer diameter of 0.5 mm wound with a bias coil was passed through the amorphous magnetic wire, and each end of the wire and each electrode were welded.
The electrode has a 0.1 mm thick JIS SK-4 semi-hard magnetic material of Table 1 (C 0.90 to 1.00, Si 0.35 or less, Mn 0.50 or less, P 0.03 or less, S 0.03 or less, Cu 0. 03 or less, Ni 0.25 or less, Cr 0.20 or less, and the balance Fe).
For comparison, a magnetic field sensor using a 0.1 mm thick copper foil as an electrode was also manufactured. However, since welding was impossible, the amorphous magnetic wire and the electrode were inevitably joined by soldering.
[0018]
In order to evaluate the welding strength between the magnetic field sensor electrode and the amorphous magnetic wire, a tensile test was performed. When the electrode was made of a semi-rigid magnetic material, the amorphous magnetic wire was strong enough to break. If the electrode was a copper foil, welding was impossible.
3, the magnetic field sensor energizing current of about 10 mA of amorphous wire, about 40 MHz, the external magnetic field Hex -0.8Oe~ + 0.8Oe, bias magnetic field of about 0.5 Oe (corresponding to 0.16Oe at 100 m A) The original output characteristics are shown.
[0019]
【The invention's effect】
According to the magnetic field detection method of the present invention, the magnetic field can be detected with the same characteristics as the conventional one using a magnetic material capable of being firmly welded to the amorphous magnetic element for the electrode of the bias magnetic field type amorphous magnetic field sensor. Even in harsh environments, stable magnetic field detection is possible.
[Brief description of the drawings]
FIG. 1 is a drawing showing an example of a linear magnetic field sensor used in the present invention.
FIG. 2 is a drawing used to explain a magnetic field detection method according to the present invention.
FIG. 3 is a chart showing sensitivity characteristics of an example of the present invention.
[Explanation of symbols]
1 Insulating substrate 2a Magnetic material electrode 2b Magnetic material electrode 3 Amorphous magnetic element 4 Bias coil 5 High frequency power supply

Claims (2)

An amorphous magnetic element is welded between electrodes, a current is passed through the element of a magnetic field sensor in which a coil is disposed in the vicinity of the element, a bias magnetic field is applied by the coil, and an external magnetic field is applied between both ends of the amorphous magnetic element. In the method of detecting from a change in voltage, a magnetic material electrode is used as the electrode of the magnetic field sensor, and the electrode is made to have a polarity opposite to the magnetization so as to suppress the magnetization of the magnetic material electrode due to a bias magnetic field and an external magnetic field. A magnetic field detection method characterized by magnetizing. Magnetic field detection method according to claim 1, wherein the magnetic material electrode is a hard magnetic material or a semi-hard magnetic material.

Images