JPS6040197B2 - Magnetoelectric conversion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetoelectric transducer using a magnetoresistive element made of a ferromagnetic material having a magnetoresistive effect, and is particularly suitable for application to a displacement sensor for detecting minute displacements. A magnetoelectric conversion device is provided.

Conventionally, a magnetic transducer using a semiconductor magnetoresistive element has been used to configure a rotation control frequency generator such as a motor, a magnetic scale reader, or a non-contact switch to configure a trout volume. There is.

By the way, semiconductor magnetoresistive elements are made of GaAs or lnSb.
Because it is formed from semiconductor materials such as An external compensation circuit is required to compensate for variations.

In addition, since semiconductor magnetoresistive elements have a magnetic field dependence of resistance that is proportional to approximately 2 squares of the magnetic field strength when the magnetic field is small, they usually require a magnetic bias of IKG or more, and Sufficient linearity cannot be obtained even in a large magnetic field region. Therefore, in a magnetoelectric transducer using such a semiconductor magnetoresistive element, it is extremely difficult to realize a displacement sensor that can detect minute displacements with good linearity. Therefore, in view of the problems in the conventional example described above, the present invention provides good temperature characteristics without using an external guarantee circuit. Another object of the present invention is to provide a magnetoelectric conversion device with a novel configuration that has small variations in resistance value and can obtain a conversion output with arbitrary magnetoelectric conversion characteristics.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings showing one embodiment.

Note that common components in each of the embodiments described below will be described using common numbers.

FIG. 1 shows the basic configuration of a first embodiment of a magnetoelectric transducer according to the present invention.

In this embodiment, the magnetoresistive element M is a flat band-shaped current path portion IC made of an anisotropic ferromagnetic material having a magnetoresistive effect such as NiCo alloy, NiFe alloy, NiAI alloy, NiMn alloy, or NiZn alloy. Power supply terminals T, L are provided at both ends in the longitudinal direction.

A constant current source CS is connected between the power supply terminals T, T2, and a constant current 1 for biasing is supplied from the constant current source CS to the current path section IC. Note that one of the power supply terminals T, , T2 (power supply terminal T2) is grounded. The magnetoresistive element MR has a bias magnetizing part MGB that generates a bias magnetic field HB having sufficient strength to saturate the ferromagnetic material forming the current passage part IC, and a signal magnetic field Hs. It is disposed opposite to the signal magnetization section MGs that is generated. The magnetoresistive element M and the bias magnetizing section MGB are fixed to each other, and are provided so as to be movable relative to the signal generating section MGs in the directions of arrows X and X in the figure. There is. Further, the bias magnet generating unit MGB is configured to normally generate a bias magnetic field HB having a strength of 10 e or more. Here, in general ferromagnetic metals, the maximum resistance value p is exhibited when the current and magnetization direction are parallel,
It has a magnetoresistive effect that exhibits the minimum resistance value p↓ when perpendicular to each other, and its resistance value per unit length p(0) is a function of the angle 8 formed by the current and the magnetization direction p(8) =p↓s
Rudder 80 p cos 20 . . . It can be expressed by the Vio-momson equation of the first equation.

Therefore, in the embodiment having the above-described configuration, the ferromagnetic material forming the current passage portion IC of the magnetoelectric conversion element MR is
Due to the bias magnetic field HB in the direction having an angle of 8 with respect to the direction of the bias current 1 flowing through the current path portion IC, rB=r↓sin8tei+r〃cos8tei per unit length.
. . . exhibits a resistance value rB of the second formula, and also has a signal magnetic field Hs having an angle of 82, so that per unit length rs r ↓ sin approximately 10 r' cos 8 ...
. . . It exhibits a resistance value rs expressed by the third formula.

If the total length in the longitudinal direction of the current path section IC of the magnetoresistive element M is 1, and the length of the current path section IC located in the signal magnetic field Hs is x, then the current path section IC
In a portion of length x in the middle, r(a)=x. (rLsin280r〃c()s28
)...Exhibits a resistance value r(0) shown by the fourth equation.

Incidentally, the angle 6 in the above-mentioned formula 4 is expressed as shown in FIG. It is determined as shown. That is, when considering the bias magnetic field HB and the signal magnetic field Hs on a Gaussian plane, the magnitude of the composite magnetic field of the bias magnetic field HB and the signal magnetic field Hs is lz+QI=ノ(x+a)20(y+b)2...
・This is the fifth equation, and its argument a'ma0=~g(z+Q)=tan-1P2...6th equation×
It is indicated by 10a.

Here, z=×1ly, .・×=HBsjno,,y
=HBcosoQ=a+ib ・.・a=Hssln8
2, b=HsCoSO.

Therefore, if i is the current value of the bias current 1 supplied from the constant current source CS between the terminals T, , T2 of the magnetoresistive element M, then V(x)=1・(1−x)・( r↓si〆0, 10r〃cos28,) 10i・x(rLsi〆80r
〃cos28)=i・1(r↓si〆8, 10r'''c
os28,) 10i・x{r↓(si〆8−sin28,
) 10r〃(cos28-cos20,)}・・・・・・
An output voltage Vx expressed by the seventh equation is obtained.

As is clear from Equation 6, if the directions of the bias magnetic field HB and the signal magnetic field Hs are constant, the output voltage Vx is determined by the length x of the current path section IC located in the signal magnetic field Hs.
can be obtained in proportion to In an embodiment with such a configuration, the current path portion IC made of a ferromagnetic material has a temperature characteristic of its resistance value that is extremely small compared to a semiconductor magnetoresistive element, and has an output characteristic with good linearity. Furthermore, it is possible to easily manufacture a magnetoresistive element MR with excellent temperature characteristics and small variation in element resistance because it can be easily manufactured into an extremely precise shape by evaporation of a ferromagnetic thin film and a photoetching process. can be formed.

Therefore, in the embodiment configured as described above, without using an external compensation circuit, the minute relative displacement between the signal magnet generating section MGs and the magnetoresistive element MR is converted into an output voltage Vx with good linearity, and each terminal T, . It can be obtained during T2.

In the above-described embodiment, the direction of the bias magnetic field HB is made parallel to the direction of the current 1 flowing through the current path section IC, and the direction of the signal magnetic field Hs is made perpendicular to the direction of the current 1 flowing through the current path section IC.
The detection sensitivity of the relative change between the signal magnetizing part MGs and the magnetoresistive element MR is the highest under the ideal condition of 8 days.

Under such ideal conditions, the above-mentioned Type 6 skin =.・
8 = Vx±i. (11x)・r〃1・x・r↓=i・1・
r〃j·x·(r↓−r〃)...The output voltage Vx expressed by the eighth equation is obtained.

Here, in order to further improve the detection sensitivity, for example, as shown in FIG.
C, may be formed of a ferromagnetic material to increase the impedance between each terminal T, , L. The operating principle of the second embodiment shown in FIG. 3 is the same as that of the first embodiment described above, so common parts are designated by reference numerals in the drawings and detailed explanation thereof will be omitted. . FIG. 4 is a configuration diagram showing a third embodiment of the magnetoelectric transducer according to the present invention.

In this embodiment, the linearity or curvilinearity of the magnetoelectric conversion characteristics is set, and the current path section IC2 of the magnetoresistive element MR2 is composed of each element IC, whose length u in the longitudinal direction is gradually increased. , lc2 . . . are formed in a broken line pattern shape by ICn.

Introduction: The current passage section IC2 is made of a ferromagnetic material having a magnetoresistive effect. The current path section IC2 has a constant current source CS connected between each power supply terminal T, T2 provided at both ends thereof, and is placed in a bias magnetic field HB and a signal magnetic field Hs in different directions. There is.
In an embodiment with such a configuration, each elemental piece ic,
, lc2, ......... With the characteristic of the function 〆(u) given by the change in the length in the longitudinal direction of lcn (the function curve is shown by the double-dot iron line in the figure), the above signal magnetic field H
The output voltage Vu can be obtained between each terminal T, T2 by performing power conversion according to the length of the current path section IC2 located in the current path section IC2. If the above function (u) is set to be a straight line, linear magnetoelectric conversion characteristics can be obtained, and if it is set to be a curve, curved magnetoelectric conversion characteristics can be obtained. It is possible to realize arbitrary magnetoelectric conversion characteristics according to the function 〆(u). FIG. 5 is a configuration diagram showing a fourth embodiment of the magnetoelectric transducer according to the present invention.

In this embodiment, a potentiometer is constructed by connecting two current path section ICs of the magnetoresistive element M shown in FIG. 1 above in series and providing an output terminal at the midpoint of the connection. It is.

That is, in this embodiment, as shown in FIG.
A magnetoresistive element MR3 is configured such that Ca and the second current path section ICb are connected in series, an output terminal T3 is provided at the midpoint of the connection, and power supply terminals T, L are provided at both ends. It is used. The magnetoresistive element M old 3 has respective power supply terminals T, . A constant voltage source VS is connected between T2, and the first current path section IC
A signal magnetizing section MGs that generates a signal magnetic field Hs in a direction perpendicular to the longitudinal direction of each current path ICa and ICb in a region Ms spanning between a and the second current path section ICb, and each current path. A bias magnet generating section MG8 that generates a bias magnetic field HB in a direction parallel to the respective current passage sections ICa and ICb is disposed in a region MB extending over the entire portions ICa and ICb, facing each other. Note that the signal magnetizing section M○s and the magnetoresistive element M old 3 are provided so as to be freely movable relative to each other.

In the embodiment with such a configuration, when the resistance value r^ of one of the first and second current path sections ICa and ICb increases with the relative movement of the signal magnetization section MGs in the longitudinal direction thereof, , exhibits a differential change characteristic such that the other resistance value rB decreases, and the total resistance value (r^+
Since rB) does not change, the constant voltage source VS. V
in. ．． ．． ．． ．． ．． ．． ．． ．． …． . . . A constant current 1 having a current value i expressed by the ninth equation 1 = ▽ is caused to flow.

Here, in the eighth equation, Vjn is the voltage applied between both terminals T, , T2 of the magnetoresistive element MR3 from the constant voltage source VS, r^ is the resistance value in the first current path section ICa, and rB
is the resistance value in the second current path portion *ICb. In addition, the above-mentioned respective resistance values are as follows. In addition, each of the above resistance values r^, r
B can be determined by the first equation described above. That is, the entire length in the longitudinal direction of the first current path section ICa is L,
, the total length in the longitudinal direction of the second current path Cb is L2, the distance between the first and second current path portions ICa and ICb is L3, the total length in the longitudinal direction of the region Ms of the signal magnetic field Hs is L,
A first current path section IC located in the signal magnetic field Hs
The length in the longitudinal direction of a is x, and the length in the longitudinal direction of the second current path portion ICb located in the signal magnetic field Hs is x2.
, then r^=(L-x,). (r↓sin280r
〃cos20,) ten×,.

(r↓s rudder 80r〃cos28)... 1st G type r8: (L2-×2)・(r'' sin28, 10r〃co
s281>10-.

(r↓Si〆a, 10r〃cos28).・…． ...The above-mentioned resistance values r^ and r8 can be determined using the first equation (11th equation) and the 11th equation.

Therefore, the total resistance value between the terminals T, T2 of the magnetoresistive element MR3 is r^+rB=(L-r.)・(r1sin2
8, ten r〃cos28,) ten×,.

(r↓si〆80r〃cos20) ten (L-x2)・(
r↓sin28, ten r〆 cos281) ten.

(rLs solution 80r〃cos28)=(L+L2)・(r
↓sin28, 10r〃c()s281)1(L+L3)
．． {(r↓sin28, 10r〃c()s201>-(r
↓s elbow 80 r〃cos 28) ......As shown in the 12th equation, which is the la equation, if the directions of the bias magnetic field HB and the signal magnetic field Hs are constant, the signal magnetic field Hs It remains constant regardless of the position.

Here, each length above is L=12=L, x, 10×2=L
-L3=Lo, and the output voltage (Vout) under the ideal conditions described above is (Se-X2)r〃+X2r
↓ Vout = {Yamaichi (X, 10 × 2)} Keju (X, 10 × 2
)r↓・VinL2Mvin ni〆-r”)Vj
n. ．． ．． ．．
．． ．． ... 1st $ formula - (4--Lek + Lr (Koichi L) r
It can be expressed by the IS equation: 〃+−r↓・equal.

The first term on the right side of Equation 13 above is a constant voltage, the second term is
The term represents a voltage that changes in proportion to the length of the signal magnetic field Hs depending on the change in position of the signal magnetic field Hs.

Here, bias magnetic field H in the magnetoelectric transducer according to the present invention configured as a potentiometer as described above.
Examples of specific structures for applying B and the signal magnetic field Hs to the magnetoresistive element M4 are shown in FIGS. 6 to 10. First, the bias generator MOB that generates the bias magnetic field HB is formed from a permanent magnet, and the magnetoresistive element M old 4
It is fixed by adhesive or the like to the substrate BB on which the current path portions IC, ^, IC, 8 are formed.

The magnetoresistive element MR is
A bias magnetic field HB can be constantly applied to 4. Magnetoresistive element MR4 integrally attached as described above
For example, as shown in FIG. 6, the signal magnetizing section MGs, which is provided relatively movably with respect to the bias magnetizing section MGB, faces each other so that the magnetoresistive element M eaves 4 is located therebetween. It consists of two permanent magnets Mg, , Mg2.

The permanent magnets M9 and Mg2 have magnetic poles of different polarities formed on surfaces facing each other with the magnetoresistive element M4 in between. In addition, as the above-mentioned signal magnetizing section MGs,
As shown in FIG. 7, one permanent magnet Mg may be used, which is disposed so as to face each of the current path portions IC, ^, IC, and B of the magnetoresistive element MR4. Furthermore, as shown in FIG. 8 or 9, by attaching magnetic yokes My, My2 made of ferromagnetic material to the permanent magnets Mg, Mg2, Mg for generating the signal magnetic field Hs, the signal magnetic field Hs can be generated. It can be strengthened. In the specific example shown in FIG. 9, the opposing portions My2' and My2' of the magnetic yoke My2, between which the magnetoresistive element M old 4 is located, are formed in a tapered shape toward the magnetoresistive element MR4. , the signal magnetic flux can be concentrated, and furthermore, the signal magnetic field H
s can be strengthened. Furthermore, as the signal magnetizing section MGs for generating the signal magnetic field Hs, an electromagnet EMg as shown in FIG. 10 may be used. As described above, in the signal generator MGs using the electromagnet EMg, the strength of the signal magnetic field Hs can be arbitrarily set by the drive current supplied to the electromagnet EMg, and can be made sufficiently strong. In this case, the permanent magnet used in the bias magnet generating unit MGo needs to have a high coercive force. FIG. 11 is a block diagram showing a fifth embodiment of the nutritional conversion device according to the present invention.

In this embodiment, a pair of potentiometers are used from the first and second fin flow passages connected in series to form a bridge circuit to improve the detection sensitivity of relative changes between the magnetizing part and the magnetoresistive element. This is what I did.

That is, in the fifth embodiment shown in FIG.
b,,ICa2,ICb2, the first and second current path portions ICa,,ICb, are connected in series to form a first potentiometer, and the third and fourth current path portions IC A magnetoresistive element M5 is used in which ICb2 is connected in series to form a second potentiometer.

A positive power supply terminal T, a is provided at one end of the first current path section IC, and the second current path section ICb,
A negative side power supply terminal T pin is provided at one end of the , and further,
A first output terminal T3a is provided at a connection midpoint connecting the other ends of each current path section ICb. Further, a negative side power supply terminal T2b is provided at one end of the third current path section IC2, and a negative side power supply terminal T2b is provided at one end of the third current path section IC2.
Positive side power supply terminals T and b are provided at one end of the circuit, and a second output terminal T3b is provided at a connection midpoint connecting each current path section ICa2 and each other end of the IC ground. Then, a,, ICa2, ICb, .
A signal magnetizing section MGs that applies a signal magnetic field Hs to a partial region Ms spanning the IC ground and the magnetoresistive element M5 are arranged opposite to each other so as to be movable relative to each other in the direction of the arrow X-X in the figure. Ru.
In addition, each of the above current path portions ICa,, IC2, ICb,
, ICb2, a bias magnetic field HB from a bias magnet generating section MGB is applied to the region Mo extending over the entirety of ICb2. Therefore, in the embodiment configured as described above, the signal magnetic field Hs generated by the signal magnetizing section MGs is applied to each current path section ICa, , ICb, , I
When the position across Cb2 is displaced by the relative movement between the signal magnetizing section MGs and the magnetoresistive element MR5, the first current path section ICa and the second current path section ICa and the second
The first potentiometer formed by the current path section ICb, and the second potentiometer formed by the third current path section ICb and the fourth current path section ICb2 operate differentially, An output voltage Vout corresponding to the amount of displacement can be obtained between the output terminal Tne and the second output terminal Tmatsu.

Note that the above output voltage Vout is applied to each output terminal T3a, T
The signal is outputted via a differential amplifier A connected between 3b and 3b.
In an embodiment of such a configuration, the output voltage Vout is a differential output between the first and second potentiometers.
Since the temperature characteristics of each potentiometer are canceled out, the temperature characteristics of the magnetoresistive element MR5 can be improved, and the displacement detection sensitivity is improved compared to the embodiment shown in FIG. can be doubled.

As shown in FIG. 12, in place of the second potentiometer consisting of the third and fourth current path portions ICb, , ICn in the fifth embodiment, series-connected resistors R, , IC2 are used. Even if the potentiometer is formed using R2 and R3, the same operation as in the fifth embodiment described above can be performed. As is clear from the description of each embodiment described above, according to the present invention, a magnetoresistive element having a current path made of a ferromagnetic material having a magnetoresistive effect, and a bias current being supplied to the current path of the resistance element. a power source; a bias magnet generating section that generates a bias magnetic field that magnetizes the current path of the magnetoresistive element in one direction over the entire area; The feature is that it is equipped with a signal magnetization section that applies to a partial area, and that an output signal is obtained according to the relative displacement between the magnetoresistive element and the signal magnetization section, thereby making it possible to use an external compensation circuit. Even without using it, it is possible to provide a magnetoelectric conversion device that has good temperature characteristics, small variations in conversion output voltage, and can obtain a conversion output with arbitrary magnetoelectric conversion characteristics. In particular, by configuring a potentiometer from two current paths crossed by magnetic fields in different directions, or by configuring a bridge circuit using a pair of the above-mentioned potentiometers, minute relative displacement between the JI power conversion element and the magnetizing part can be realized. can be detected with high sensitivity and good linearity, it is possible to realize a magnetic force conversion device that is most suitable for application as a minute displacement sensor, and the intended purpose can be fully achieved.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention. FIG. 2 is an explanatory diagram schematically showing the direction of the magnetic field applied to the magnetoresistive element in the first embodiment. FIG. 3 is a configuration diagram showing a second embodiment of the present invention. FIG. 4 is a configuration diagram showing a third embodiment of the present invention. FIG. 5 is a configuration diagram showing a fourth embodiment of the present invention. FIGS. 6 to 10 are external perspective views showing specific examples of how the bias magnetizing section and the signal magnetizing section are attached to the present invention. FIG. 11 is a configuration diagram showing a fifth embodiment of the present invention. FIG. 12 is a configuration diagram showing a sixth embodiment of the present invention. 1...Bias current, IC, IC,,
IC2, ICa, ICb, IC, ^, IC, 8, ICa
,,ICb,,ICa2,IC snake...current path, MR,Mnagi,. M old 2. M old 3, N rudder 4, M old 5...
... Magnetoresistive element, MG8... Magnetizing part for bias,
MGs...Signal magnet generating section, HB...Bias magnetic field, Hs...Signal magnetic field. Figure 2 Figure 6 Figure 1 Figure 3 Figure 4 Figure 7 Figure 8 Figure 5 Figure 9 Figure 10 Figure 11 Figure 12

Claims (1)

[Scope of Claims] 1. A magnetoresistive element having a current path made of a ferromagnetic material having a magnetoresistive effect, a power supply supplying a bias current to the current path of the magnetoresistive element, and a current path of the magnetoresistive element. a bias magnet generating section that generates a bias magnetic field that magnetizes in one direction over the entire area; and a signal magnet generating section that applies a signal magnetic field in a direction different from the bias magnetic field to a partial region of the current path of the magnetoresistive element. What is claimed is: 1. A magneto-electric transducer comprising: a magnetoresistive element and a signal magnet generating section, wherein an output signal is obtained according to a relative displacement between a magnetoresistive element and a signal magnet generating section. 2. The magnetoelectric transducer according to claim 1, wherein the magnetoresistive element has a current path in the form of a broken line pattern whose longitudinal direction is a direction intersecting the region of the signal magnetic field. Magnetoelectric conversion device. 3. The magnetoelectric transducer according to claim 2, wherein the length of each path element in the longitudinal direction of the current path of the magnetoresistive element is made different. 4. First and second current paths each made of a ferromagnetic material having a magnetoresistive effect are connected in series, and an output terminal is provided at a connection point between the first current path and the second current path. a magnetoresistive element to which a bias current is supplied from a power supply terminal provided at each other end of each current path; a power source that supplies bias current to each current path of the magnetoresistive element; and each current path of the magnetoresistive element. a bias magnet generating section that generates a bias magnetic field that magnetizes in one direction over the entire area; and a signal generator that applies a signal magnetic field in a direction different from the bias magnetic field to a partial region spanning each current path of the magnetoresistive element. 1. A magnetoelectric transducer comprising: a magnetic section, and configured to obtain an output signal according to relative displacement between a magnetoresistive element and a signal magnet generating section. 5. The magnetoelectric conversion device according to claim 4, comprising a pair of magnetoresistive elements having the first and second current paths, and supplying power of opposite polarity to each magnetoelectric conversion element to connect each output terminal. A magneto-electric conversion device characterized in that a differential output signal is obtained between the two.