JPS6134604B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnet generating body that generates a plurality of magnetic fields in different directions adjacent to each other with clear boundaries, and particularly relates to a displacement sensor using a magnetoresistive element having a magnetoresistive effect. The present invention provides a magnet-generating body that is suitable for use as a magnet-generating part, etc.

Conventionally, magnetoelectric transducers using regular-sized conductor magnetoresistive elements have been used to construct frequency generators for controlling the rotation of motors, magnetic scale readers, non-contact switches, non-contact volumes, etc. There is.

By the way, semiconductor magnetoresistive elements include GaAS and
Since it is formed from a semiconductor material such as InSb, the number and mobility of carriers are highly temperature dependent, resulting in poor temperature characteristics and large variations in resistance value from element to element. Requires external compensation circuit to compensate for variations. In addition, semiconductor magnetoresistive elements have a magnetic field dependence of resistance that is approximately proportional to the square of the magnetic field strength when the magnetic field is small, so they usually require a magnetic bias of 1 KG or more, and also require a large magnetic bias. Sufficient linearity cannot be obtained even in the 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.

Compared to such a magnetoelectric transducer using a semiconductor magnetoresistive element, a magnetoelectric transducer using a magnetoresistive element made of a ferromagnetic material having a magnetoresistive effect can clearly convert multiple magnetic fields in different directions. By detecting signal magnetic fields that are adjacent to each other with a boundary, it is possible to realize a displacement sensor that has excellent temperature characteristics and very good detection characteristics with little variation in resistance value without using an external compensation circuit.

However, in general, generating a magnetic field whose direction changes discontinuously across a certain boundary line is
It is said to be an almost impossible technique.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a magnet generating body that can generate a plurality of magnetic fields having different directions adjacent to each other with clear boundaries.

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 structure of a first embodiment of a magnetoelectric transducer constructed using a magnetic body according to the present invention.

In this example, the magnetoresistive element MR is
A current path portion in the form of a broken line pattern made of an anisotropic ferromagnetic material having a magnetoresistive effect such as NiCo alloy, NiFe alloy, NiAl alloy, NiMn alloy, or NiZn alloy.
A constant current source CS is connected between power supply terminals T ₁ and T ₂ at both ends of the IC in the longitudinal direction, and a constant current I for bias is caused to flow from this constant current source CS to the current path section IC. Note that one of the power supply terminals T ₁ and T ₂ (power supply terminal T ₂ ) is grounded.

The magnetoresistive element MR has sufficient strength to saturate magnetize the ferromagnetic material forming the current path portion IC, and has a boundary line that crosses the longitudinal direction of the current path portion IC. It is disposed opposite to a magnet generator MG that generates a first magnetic field Hs and a second magnetic field _Hn having different directions. The first magnetic field H _s
The region M _s of the second magnetic field H n is indicated by a broken line in FIG. 1, and the region M _n of the second magnetic field H _n is indicated by a chain line in FIG.

Here, FIG. 2 shows a specific example of the configuration of a magnetizing body MG having a region M _{s of a first magnetic field H s and} a region M _n of a second magnetic field H _n having boundary lines and different directions. show. That is, in Figure 2, Ns
is a magnetized belt magnetized to the north pole to generate the first magnetic field Hs, S _s is a magnetized belt also magnetized to the south pole, and N _n is the magnetized belt magnetized to the north pole to generate the first magnetic field Hs. The magnetized belt is magnetized to the north pole to generate H _n , and S _n is also the magnetized belt magnetized to the south pole. The magnetized belts N _s and S _s are arranged parallel to each other and mutually with an interval P between them. Similarly, the magnetized bands H _n and S _n are arranged parallel to each other and alternately. The magnetized bands N _s , S _s and the magnetized bands N _n , S _n are brought into contact with each other at different angles θ ₁ and θ ₂ with respect to the boundary line, respectively, at their longitudinal ends. has been done. Magnetic generating body with such a configuration
MG is the first magnetic field in the direction orthogonal to the above magnetized zones Ns and Ss.
The magnetic field H _s is generated, and the magnetized belt N _n ,
A second magnetic field Hm orthogonal to S _n is generated. Furthermore, by reducing the distance P between the magnetized bands N _s , S _s and the magnetized bands N _n , S _n , the range in which each magnetic field interacts near the boundary line becomes narrower. A clear boundary between the magnetic field H _s and the second magnetic field H _n can be provided.

In this example, the magnetoresistive element
MR and the magnet generating body MG are provided so as to be relatively movable in the longitudinal direction (arrow X in FIG. 1) of the current passage section IC, and by moving the magnet generating body MS, the above-mentioned The position of the boundary line that crosses the current path section IC moves.

Generally, for ferromagnetic metals, the maximum resistance value ρ‖ is reached when the current and magnetization direction become parallel.
It has a magnetoresistance effect such that it exhibits a minimum resistance value ρ⊥ when they are perpendicular to each other, and its resistance value per unit length ρ(θ) is a function of the angle θ between the current and the magnetization direction ρ (θ)=ρ⊥sin ² θ+ρ‖con ² θ...It can be expressed by the Viogt-Thomson equation of the first equation.

Therefore, in the embodiment with the above-mentioned configuration,
The ferromagnetic material forming the current passage part IC of the magnetoresistive element MR is caused to have a unit length by a first magnetic field Hs in a direction having an angle θ ₁ with respect to the direction of the bias current I flowing through the current passage part IC. Hitting r _s = r⊥sin ² θ ₁ + r‖cos ² θ ₁ ......Exhibits the resistance value r _s of the second formula, and also due to the second magnetic field H _n having an angle θ ₂ , the unit length Hitting r _n =r⊥sin ² θ ₂ +r‖con ² θ ₂ . . . The resistance value r _n is expressed by the third formula.

Since a constant bias current I is passed from a constant current source CS to the current path IC of the magnetoresistive element MR, the current value of the bias current I is defined as i, and the total length in the longitudinal direction of the current path IC. If L is the length of the current path section IC located in the second magnetic field _Hn , then the terminals T ₁ and T ₂ provided at both ends of the current path section IC have Vx. _{= i . _} This results in the output voltage Vx being obtained.

_{Here ,} α in the fourth equation above is a constant expressed by the fifth equation, α=r _n / _rs . Takes a value. That is, when H _s is an orthogonal magnetic field, r _s is minimum, and when H _n is a parallel magnetic field, _on is maximum, α=r‖/r⊥, and the constant α takes the maximum value. In other words, this constant α is such that the magnetic field H _s is orthogonal to the current path portion IC, and the magnetic field H _n
It takes the maximum value when the two are parallel. Here, since the positions of the magnetizing bodies are swapped and become relatively the same, the above constant α is determined by one of the magnetic fields H _s and H _n with respect to the direction of the current I flowing through the current path portion IC. The maximum value is obtained when the two are orthogonal and the other is parallel. In the embodiment according to the present invention, the directions of the magnetic fields H _s and H _n with respect to the direction of the current I are made different, so the constant α is never equal to 1.

As is clear from the fourth equation above, each terminal T ₁ ,
The output voltage Vx obtained during T ₂ has a voltage value proportional to the length x, and the output voltage _Vx obtained during T 2 has _a voltage value proportional to the length
The boundary line between them is the current path IC of the magnetoresistive element MR.
can be obtained corresponding to the position across the .

In addition, the current path IC made of a ferromagnetic material has an extremely small temperature characteristic of its resistance value compared to a semiconductor magnetoresistive element, and has a temperature characteristic with good linearity. Since it can be easily manufactured into an extremely precise shape by vapor deposition and photoetching processes, it is possible to form a magnetoresistive element MR with excellent temperature characteristics and small variations in element resistance.

Therefore, in the embodiment with the above-mentioned configuration, the magnetizing body MG and the magnetoresistive element can be easily connected without using an external compensation circuit.
Using MR, a minute relative displacement can be converted into an output voltage V _x with good linearity, which can be obtained between each terminal T ₁ and T ₂ .

Note that in this embodiment, when the output _{voltage V
s} ) is at its maximum, that is, when the constant α determined by the ratio of r _n and r _s becomes maximum. Since the maximum ratio of relative changes means the maximum detection sensitivity, the difference between the first magnetic field H _s and the second magnetic field H _n with respect to the direction of the current I flowing through the current path IC. The above magnetizing body is formed so that one direction is perpendicular and the other direction is parallel, and the above-mentioned constant α is
When is set to take the maximum value, the detection sensitivity of the relative displacement between the magnetizing body MG and the magnetoresistive element MR becomes the highest. The specific configuration of such a magnetizing body MG is explained in the third section.
As shown in the figure.

That is, in the magnetizing body MG ₁ shown in FIG. 3, each magnetized belt N _{s and} S _s are arranged in a region M _s parallel to the boundary line, and each magnetized belt N _n is arranged in a region M _n . ，
S _n is arranged parallel to the boundary line. Moreover, the distance P between each of the above magnetized belts N _n and S _n
is the _interval λ between the individual pieces ic ₁ , ic ₂ , . It is set as shown in Equation 6.

Note that n in the sixth formula is any positive integer.

FIG. 4 is a configuration diagram showing a second embodiment of a magnetoelectric conversion device constructed using a magnetizing body according to the present invention.

In this embodiment, a current path IC made of a ferromagnetic material is used.
A potentiometer is constructed by connecting two in series and providing an output terminal at the midpoint of the connection.

That is, in this embodiment, as shown in FIG. 4, each planar band-shaped first current path section IC _a and second current path section IC _b made of a ferromagnetic material are connected in series. In addition, an output terminal _T3 is provided at the midpoint of the connection, and power supply terminals are provided at both ends.
A magnetoresistive element MR ₁ provided with T ₁ and T ₂ is used. The magnetoresistive element MR ₁ has a constant voltage source VS connected between each power supply terminal T ₁ and T ₂ , and a first boundary line a and a first boundary line _a crossing the first current path part IC _a . In the first region M ₁ between the second boundary line _b that crosses the current path portion IC _b of 2, the first magnetic field H ₁ in the direction perpendicular to the longitudinal direction of each current path portion IC _{a and} IC _b is applied. In the second magnetic field region M 2 and the third magnetic field region M ₃ which are adjacent to each other via the boundary lines _a and _b , the second magnetic field region M ₂ and the third magnetic field region M 3 in the direction parallel to the longitudinal direction of each current path portion IC _a and IC _b Magnetizers MG ₂ that generate third magnetic fields H ₂ and H ₃ are disposed facing each other so as to be relatively movable.

In order to generate the first to third magnetic fields H ₁ , H ₂ , H ₃ , for example, a magnet generator MG ₂ having a configuration as shown in FIG. 5 is used. That is, in FIG. 5, in the region M ₁ where the magnetized bands S ₁ and _{N 1} are arranged parallel to each other and alternately with the longitudinal direction being orthogonal to the boundaries _a and b, the boundaries _a , A first magnetic field H ₁ parallel to _b can be generated. In addition, in each region M ₂ and M ₃ where the magnetized bands S ₂ and N ₂ and S ₃ and N ₃ are arranged parallel to each other and alternately with the longitudinal direction parallel to each boundary line _a and _b , Second and third magnetic fields H ₁ and H ₃ in directions perpendicular to the boundary lines _a and _b can be generated.

The first and second current path portions IC _a and IC _b arranged in the first to third magnetic fields H ₁ , H ₂ , H ₃ generated by such a magnet generator MG ₂ are connected to the magnetic field. As the boundaries _a and _b of H ₁ , H ₂ , and H ₃ move in the longitudinal direction, the resistance value R _A of one increases and the resistance value R _B of the other decreases. , and the total resistance value between terminals T ₁ and T ₂ (R _A + R
_B ) does not change, so the constant voltage source VS generates a constant current I having a current value i expressed by the seventh equation: i=V _io /R _A +R _B
will be washed away. Here, in the seventh equation, V _io is the voltage applied between both terminals T ₁ and T ₂ of the magnetoresistive element MR ₁ from the constant voltage source VS, and R _A is the resistance in the first current path section IC _a. The value R _B is the resistance value in the second current path portion IC _b . Note that each of the resistance values R _A and R _B can be determined by the first equation described above.

Therefore, in the embodiment with the above-mentioned configuration,
A magnet is connected between the output terminal T ₃ provided at the midpoint of the connection between the series-connected current path sections IC _a and IC _b and the ground.
It is possible to obtain an output voltage _Vput whose voltage level changes depending on the relative displacement between MG ₂ and magnetoresistive element MR ₁ .

FIG. 6 is a configuration diagram showing a third embodiment constructed using a magnetizing body according to the present invention.

In this embodiment, the first and second
A bridge circuit is constructed by using a pair of potentiometers each having a current path section of 1, to improve the detection sensitivity of relative changes between the magnetoresistive element and the magnetoresistive element.

That _{is ,} in the _third embodiment shown in _FIG . Passage portions IC _a1 and IC _b1 are connected in series to form a first potentiometer, and third and fourth current path portions IC _a2 and IC _b2 are connected in series to form a second potentiometer. A magnetoresistive element MR ₂ is used. A positive power supply terminal T _1a is provided at one end of the first current path IC _a1 , a negative power supply terminal T _2a is provided at one end of the second current path IC _b1 , and , a first output terminal T _3a is provided at a connection midpoint connecting the other ends of each of the current path portions IC _a1 and IC _b1 . Further, a negative side power supply terminal T2b is provided at one end of the third current path section IC _b1 , and a fourth current path section IC b1 is provided with a negative side power supply terminal _T2b .
A positive power supply terminal T _1b is provided at one end of IC _b2 , and a second output terminal T _3b is provided at the connection midpoint connecting the other ends of each current path section IC _a2 and IC _b2 . ing.

Then, each of the above current path portions IC _a1 , IC _a2 , IC _b1 ,
First to fourth magnetic fields H _{a ,} H b , H having mutually different directions with a boundary line ₁ crossing IC _b2 and a boundary line 2 dividing between the first and second current path portions IC _{a1 and} IC _b1 The magnet G ₃ that generates _C and H _d and the magnetoresistive element MR ₂ are arranged opposite to each other so as to be relatively movable in the direction of the arrow X-- in the figure.

Here, the first to fourth magnetic fields H _a , H _b ,
To generate H _c and H _d , a magnet generator MG ₃ having a configuration as shown in FIG. 7 is used.

That is, the magnet generator MG ₃
In _{the first} and _third regions M _a , M _c of the first to fourth regions M a , M _b , M _c , M _d divided into four by 1 and 2, an N- _pole magnetized zone is formed. The N _ac and the S-pole magnetized belt S _ac are arranged parallel to the boundary line ₁ and alternately, and the second and fourth regions M _b , M _d
, N-pole magnetized belts N _bd and S-pole magnetized belts S _bd are arranged parallel to boundary ₁ and alternately. The magnetizing body MG ₃ having such _a configuration has adjacent regions _{M a ,} M _b , M
It is possible to generate first to fourth magnetic fields _Ha , _Hb , _{Hc ,} and _Hd in mutually orthogonal directions at C _{and Md} . Note that the directions of the first and third magnetic fields H _a and H _c are parallel to each other, and the directions of the second and fourth regions H _b and H _d are parallel to each other; The directions of the first and third magnetic fields H _a and H _c and the directions of the second and fourth regions H _b and H _d are orthogonal to each other.

Therefore, the boundary line ₁ of each magnetic field H _a , H _b , H _c , H _d generated by the magnetizing body MG ₃ as described above corresponds to each current path portion IC _{a2 ,} IC _a1 ,
When the position across IC _b1 and IC _b2 is displaced by the relative movement of the magnetoresistive element MG ₃ and the magnetoresistive element MR ₂ , the first current path section IC _a1 changes according to the amount of displacement.
The first potentiometer formed by the second current path section IC _b1 and the second potentiometer formed by the third current path section IC _a2 and the fourth current path section IC _b2 are different from each other. operates dynamically and the first output terminal
An output voltage V _put can be obtained between T _3a and the second output terminal T _3b according to the amount of displacement.

In an embodiment with such a configuration, since the output voltage V _put is obtained as a differential output between the first and second potentiometers, the temperature characteristics of each potentiometer are canceled out, and the magnetoresistive element MR In addition to improving the temperature characteristics as shown in _FIG .

As is clear from the above-mentioned embodiments, according to the present invention, there are at least two magnetized regions in which adjacent magnetized regions are arranged in parallel, each of which is magnetized with opposite polarity, and each By making the parallel arrangement directions of the magnetized bands in the magnetized regions different from each other, and by arranging each magnetized region adjacent to each other with a boundary line, it is possible to clearly distinguish multiple magnetic fields with different directions. It is possible to provide magnetic generating bodies that are generated adjacently with a boundary. Therefore, by applying the magnetizing body of the present invention to a displacement sensor using a magnetoresistive element made of a ferromagnetic material having a magnetoresistive effect, it is possible to realize a displacement sensor with extremely good detection characteristics. Therefore, the intended purpose can be fully achieved. It goes without saying that the present invention is not only applicable to the magnetoelectric conversion device in the above-described embodiments, but also to other devices that utilize magnetic action.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a first embodiment of a magnetoelectric conversion device constructed using a magnetizing body according to the present invention. FIG. 2 is a plan view of a main part showing a specific configuration of the magnetizing body according to the present invention applied to the first embodiment. FIG. 3 is a plan view of a main part showing a specific configuration of the magnetizing body according to the present invention when the detection sensitivity is maximized in the first embodiment. FIG. 4 is a configuration diagram showing a second embodiment of a magnetoelectric conversion device constructed using a magnetizing body according to the present invention. Fifth
The figure is a plan view showing a specific configuration of the magnetizing body according to the present invention applied to the second embodiment. FIG. 6 is a configuration diagram showing a third embodiment of a magnetoelectric conversion device constructed using a magnetizing body according to the present invention. 7th
The figure is a plan view showing a specific configuration of the magnetizing body according to the present invention applied to the third embodiment. 1...Bias current, IC, IC _a , IC _b , IC _a1 ,
IC _b1 , IC _a2 , IC _b2 ...Current path, MR, MR ₁ , MR ₂
... Magnetoresistive element, , _a , _b , ₁ , ₂ ... Boundary line, MG, MG ₁ , MG ₂ , MG ₃ ... Magnetizing body, N _s , S
_s , N _n , S _n , N ₁ , S ₁ , N ₂ , S ₂ , N ₃ , S ₃ , N _ac ,
S _ac , N _bd , S _bd ... Magnetized zone, H _s , H _n , H ₁ , H ₂ ,
_Ha , _Hb , _Hc , _Hd ...magnetic field.

Claims (1)

[Claims] 1. It has at least two magnetized regions, each of which is made up of parallelly arranged magnetized bands that are magnetized with opposite polarities, and the parallel arrangement directions of the magnetized bands in each magnetized region are different from each other. Also, a magnetizing body characterized in that each magnetized region is arranged adjacent to each other with a boundary line.