JPS6012783A - Electromagnetic conversion element - Google Patents

Abstract

PURPOSE:To obtain the titled element having three terminals of extremely compact size and high accuracy by a method wherein a plurality of magnetic resistors are arranged in series to a required shape, and then bias current terminals and an output terminal are attached at fixed positions. CONSTITUTION:Ferromagnetic substances A and B of 80 Ni-20 Co alloy are formed on an insulation substrate 7, parallel linear parts 8 and 9 being successively connected in zigzag form, respectively; and bent parts 10 and 11 then being made parallel to one another. The substances A and B are connected in series at ends 8a and 9a of the linear parts, and the output terminal 4 is attached at this part, and the current terminals 2 and 3 at the other ends. Accordingly, the full length of the magnetic substance becomes longer, and the resistance larger, resulting in the miniaturization of the element 1; therefore the output voltage can be increased by the inhibition of consumed power. The linear parts 8 and 9 are so arranged as to be in the same number and to intersect each other rectangularly, and the bent parts 10 and 11 to intersect the respective linear parts rectangularly. The resistances at the time of saturated magnetization in the direction vertical and horizontal to that of the current simultaneously vary with temperatures, respectively; consequently zero point drift hardly occurs. Thus, the title element having three terminals of small size and high accuracy can be obtained while holding each characteristic of a hall element and a magnetic resistance element.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetoelectric transducer, and particularly provides a magnetoelectric transducer that is most suitable for application to brushless motors and the like.

2. Description of the Related Art In brushless motors, it has been known to detect the position of a rotor using a magneto-electric conversion element in order to sequentially switch the current flowing through the stator coil.

Examples of this magnetoelectric conversion element include a semiconductor Hall element,
There are semiconductor magnetoresistive elements, planar ball elements, magnetic magnetoresistive elements, and the like. Among these, elements using semiconductors have poor temperature characteristics due to large temperature changes in the number and mobility of carriers, and therefore require an external circuit for temperature compensation.

Furthermore, since the magnitude of the output signal changes depending on the strength of the magnetic field, when used as a switching element that detects the direction of the magnetic field, such as in a brushless motor, it is necessary to improve the magnetic properties and mechanical precision of the signal magnetic field forming means. It is necessary to provide a remic effect to the external circuit, which is disadvantageous in terms of cost in any case.

On the other hand, since an element using a magnetic material usually uses a metal magnetic material, temperature changes in resistivity and magnetoresistance coefficient are small, and the temperature characteristics are good.

Furthermore, as a property of the magnetic material itself, it becomes saturated when the signal magnetic field exceeds a certain level, so it has a reversing effect on fluctuations in the magnitude of the signal magnetic field.

Therefore, when used as a switching element that detects the direction of a magnetic field, such as in a brushless motor, it can be said that an element using a magnetic material is more advantageous than an element using a semiconductor in terms of wood quality. However, among conventional magnetoelectric conversion elements using magnetic materials, planar Hall elements have a small output voltage, and require special peripheral circuits such as high-gain amplifiers to be used for purposes such as driving brushless motors. It has the disadvantage of being necessary. Furthermore, although magnetoresistive elements can provide a large output voltage, since they are two-terminal elements, the unbalanced voltage is about two orders of magnitude larger than the output voltage. Fluctuations in the unbalanced voltage caused by this cannot be ignored compared to the output voltage, and therefore zero point drift due to temperature changes becomes a practical problem.

By combining a plurality of magnetoresistive elements, the present invention eliminates the above-mentioned drawbacks while retaining the features of a planar Hall element and magnetoresistive elements, and can be configured extremely compactly and easily manufactured with high precision. The present invention relates to a three-terminal magnetoelectric transducer that can be provided.

Next, the basic principle and structure of the magnetoelectric conversion element of the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, a magnetoelectric transducer (1) consists of flat ferromagnetic materials A and B having a magnetoresistive effect. The ferromagnetic materials A and B are arranged so that their longitudinal directions are perpendicular to each other, and are electrically connected to form a series circuit. Current terminals (2) and (3) for supplying bias current are provided at both ends of this series circuit, and an output terminal (4) for taking out the output voltage is provided at the midpoint of the connection. The current terminals (2) and (3) are connected to a power source (5), and one of the current terminals (3) is grounded, forming a magnetoelectric conversion circuit (6) as a whole.

Magnetic field T sufficient to saturate this ferromagnetic material A, 13
-1 in the plane formed by ferromagnetic materials A and H, ferromagnetic material A
It is applied in the longitudinal direction of , that is, in the direction intersecting the current direction at an angle θ. Generally, when saturated magnetized, the resistance of a ferromagnetic material changes depending on the anisotropy of magnetic resistance, so the magnetic field I]
Depending on the angle θ formed by ρ7 represents the resistance when the magnetic material is saturated magnetized in the direction perpendicular to the current, and ρ7 represents the resistance when the ferromagnetic material is saturated magnetized in the direction parallel to the current.

On the other hand, since the equivalent circuit of FIG. 1 is as shown in FIG. 2, the voltage V(θ) at the output terminal (4) is as follows. this(
Substituting the above equations (1) and (2) into equation 3) and rearranging, we get (where Δρ=ρ7−ρ□). In this equation (4), the first term on the right side is the reference voltage V
S (VSFVO/2), the second term is the amount of change ΔV(θ)
are shown respectively. If we focus on the current transformation ■ΔV(θ), we get the following. However, 2ρ. =ρ7+ρ, where ρ0 is the resistance when no magnetic field is applied.

Therefore, the output terminal (4) shows an output change depending on the direction of the magnetic field H, and θ is 0 degrees or 180 degrees, and 90 degrees or 27 degrees.
Each reaches its maximum value at 0 degrees. However, since the direction of change is opposite, it can be seen that using two magnetic fields with θ of 0 degrees and 90 degrees maximizes the amount of change and is optimal for performing a switching operation.

As can be seen from equation (5) above, changes in the output voltage are unrelated to the strength of the magnetic field, so even if the strength of the magnetic field I changes depending on its direction, the magnetic field H will change regardless of this change.
It is possible to generate an output according to the direction of the direction. However, it goes without saying that the strength of the magnetic field H must be such that the ferromagnetic materials A and B can be magnetized to saturation.

Furthermore, as can be seen from equation (5) above, this element (1)
In order to increase the change in output voltage with respect to the direction of the magnetic field, it is necessary to configure the ferromagnetic materials A and B with magnetic materials with a large Δρ/ρ. For example, 'If; Δρ/ρ at 7j%.

The following ferromagnetic metals with a magnetic flux of 2% or more are known, and these can be used as materials for the element of the present invention.

(The following is a margin, continued on the next page.) Among these, 8ONi-20Co alloy has Δρ/ρ. 6.
It is the most excellent material at 48%, and is the most excellent material in practical use because it has better oxidation resistance and lower cost than Ni-Fe alloys, and also has good solderability.

As can be seen from equation (5), the other requirement for increasing the output voltage change is the power supply voltage ■. By increasing this value, it is possible to increase the output voltage by selecting the right material. However, when used at a high power supply voltage, the power consumption of the element (1) generally increases and heat is generated, which is not preferable. Power consumption W is V. 0
Proportional to the square of impedance ρ. is inversely proportional to <W”
Vo''/2ρ.) Therefore, if the impedance of element (1) is also increased at the same time, the output voltage can be increased without increasing power consumption.

In the magnetoelectric conversion element (1) of the present invention, F of the ferromagnetic materials A and B
Since the width of the current path can be narrowed without changing J, the impedance ρ mentioned above. can be easily increased, and therefore an output voltage that is one to two orders of magnitude higher than the output voltage of a conventional planar Hall element can be obtained.

Furthermore, in the above equation (3), ρ7 and ρ□ each change depending on the temperature, but when they change, ρ7 and ρ change simultaneously, so Δρ and ρ. If the temperature change is extremely small, the output voltage change amount ΔV(θ) is hardly affected.

Also, since the magnetoelectric conversion element (1) is a three-terminal element, the current terminal (3) can be grounded as a common terminal for the output terminals.
Therefore, peripheral circuits such as a power supply circuit can be simplified.

Next, a specific example of the magnetoelectric transducer (1) according to the present invention is shown in FIG.

The magnetoelectric transducer (1) includes an insulating substrate (7) such as a slide glass or a photographic plate that has been subjected to surface cleaning treatment, and an 8ONi-20Go alloy coated on the surface of the substrate (7) with 600 to 1
The ferromagnetic materials A and B have a polygonal or zigzag shape formed by vapor deposition to a thickness of 1,000 mm and then remove unnecessary parts, and the output formed approximately in the middle of these ferromagnetic materials A and B. It consists of a terminal (4) and current terminals (2) and (3) formed at the other ends of the ferromagnetic bodies A and B. Ferromagnetic type, B has 17 straight sections, i.e. strip elements (8) and (9), which serve as main current paths, and these straight sections (8) and (9) are connected to each other at one end. It consists of bent parts, that is, connecting parts (10) and (11). That is, the ferromagnetic materials A and B each have a plurality of straight portions (8) extending parallel to each other in a zigzag shape.
, (9), and a plurality of bent portions (10) sequentially connecting these plurality of straight portions (8) and (9) and extending parallel to each other.
, (11). In addition, the straight part (8), (
9) At the ends (8a) and (9a) of the ferromagnetic material Δ, B
are connected to each other in series, and an output terminal (4) is taken out from this connection.

The reason for this configuration is to make the total length of the ferromagnetic materials A and B extremely long. As a result, it is possible to reduce the resistance of the ferromagnetic material Δ, B, thereby increasing the impedance of the element (I,), and also making it possible to downsize the element (1). Therefore, as described above, it is possible to suppress an increase in power consumption and increase the output voltage.

In addition, the respective envelopes of both ends of the linear portions (8) along the arrangement direction in which the linear portions (8) of the ferromagnetic material A are sequentially arranged from the current terminal (2) side to the output terminal (4) side. is substantially parallel to the straight line portion (9), that is, in the vertical direction in FIG.

In addition, the envelopes of both ends of the straight parts (9) of the ferromagnetic material B along the arrangement direction in which the straight parts (9) of the ferromagnetic material B are sequentially arranged from the current terminal (3) side to the output terminal (4) side. The line is approximately parallel to the straight section (8), ie in the horizontal direction in FIG.

Therefore, the straight line portion (8) closest to the current terminal (2) side of ferromagnetic material A and the straight line portion (9) closest to the current terminal (3) side of ferromagnetic material B are spaced apart from each other by an appropriate distance Ml, and the output terminal (
It will also be placed at a suitable distance from 4). Therefore, as is clear from FIG. 3, the output terminal (4) is located in the middle of the element (1), and the pair of current terminals (2),
(3) can be placed on both sides of the element (1), so that the lead wires can be connected to these terminals (2), (3), (4).
) is extremely easy to wire.

- In addition, the straight portions (8) and the straight portions (9) are the same in number and are arranged to be approximately orthogonal to each other, and the bent portions (lO) and the straight portions (8) are approximately orthogonal to each other and are arranged to be approximately perpendicular to each other. The curved part (11) and the straight part (9) are arranged to be substantially orthogonal to each other.Therefore, the resistance ρA of the ferromagnetic material A
(θ) and the resistance ρ of the external body B, it is extremely easy to make the sum of l(θ) exactly constant regardless of the angle θ formed by the magnetic field H.

In addition, the ferromagnetic materials A and B are each formed into a rectangular shape as a whole.If the overall shape of the ferromagnetic materials A and B is particularly square, then these ferromagnetic materials Δ and B are approximately connected to each other. By making the two ferromagnetic materials A and B adjacent to each other in the same shape and rotating them by 90 degrees, the entire structure of the two ferromagnetic materials A and B becomes a rectangular shape with a long side to short side ratio of 2:l, making it extremely compact. .

Next, '1' of element (1) shown in FIG. Describe X-ness. For example, if the film thickness of ferromagnetic materials A and B is (li00), the total resistance 2ρ0 becomes 2.5Ω, and if the driving voltage is shifted to 8V, an output voltage of 160rnV is generated. The saturation magnetic field is 5000 or more, and the power consumption is about 26 InW, which shows that the strength of the magnetic field required to operate element (1) is low, and the power consumption is also low.This element When the drive voltage in (1) is set to 12V, the output voltage is 240mV and the power consumption is approximately 58mW.Also, if the film thickness of the ferromagnetic materials A and B is, for example, 1000, the total resistance 2ρ becomes 1.4Ω, and if the drive voltage is set to 8V, an output voltage of 180mV is generated.The saturation magnetic field at this time is 5000 or more, and the power consumption is about 47mW. When the drive voltage is 12V, the output voltage is 27'Om.
V, and the power consumption is approximately 103 mW.

Next, FIG. 4 shows the dependence of the output voltage on the angle of the magnetic field when the element (1) with a film thickness of 1000 is placed in a magnetic field of 3 KOe. In this figure, the vertical axis represents the amount of change Δ■(θ) in the output voltage, and the horizontal axis represents the angle θ.

Note that the angular origin is shifted by π/4 from the point in FIG. As is clear from FIG. 4, the output voltage change becomes a sine curve, and it can be seen that the above equation (5) is correct. When θ is -π/4, the output voltage is 104 mV, when θ is zero, that is, the output voltage is zero at the angle origin, when θ is π/4, the output voltage is approximately -103 mV, when θ is π/2, the output voltage is zero, and θ is 3
At π/4, the output voltage was 104 rnV, and when θ was π, the output voltage was zero.

Although the present invention has been described above based on one embodiment, it will be understood that further modifications can be made based on the idea of technique 11'r of the present invention. For example, when applying a non-uniform magnetic field, it is of course possible to provide the ferromagnetic material B on the back side of the substrate (7) and to separate the ferromagnetic material A and the substrate (7) so that they face each other. Further, as shown in the equivalent circuit diagram in FIG. 5, for example, three equivalent magnetoelectric transducers (1) can be connected in parallel and a power source (5) can be used in common. In this case, resistance ρA (θ)1 ρB (θ)−ρ7+ρ□−
2ρ0, ρ. -Since it is constant, mutual interference between the elements does not occur even if each element operates differently. Note that it is of course possible to connect a plurality of elements (1) in series. Also, the ferromagnetic material Δ, B is Nt-G.

Δρ/ρ in addition to alloys. For example, 8ONi-20 where
It can be made of Fe or the like, and in this case it is easily magnetized even in a weak signal magnetic field. Furthermore, in order to further increase the impedance, the straight parts (8) and (9
) can be changed in various ways, such as by making the width even smaller.

The magnetoelectric conversion element of the present invention can be applied to detecting the rotor position of a brushless motor, other switching operations, detecting the direction of a magnetic field, etc.

Furthermore, in the above example, metal is used as the ferromagnetic material, but in general, any material that has both magnetoresistive effect and metallic electrical conductivity can be used.

As described above, the present invention has a ferromagnetic film having an anisotropic magnetoresistive effect formed on one surface of the substrate, so it has the characteristics of a magnetoelectric transducer using a magnetic material, and therefore has the characteristics of a magnetoelectric transducer using a magnetic material. It exhibits saturation characteristics and has a limiter effect on fluctuations in the magnitude of the signal magnetic field, resulting in extremely poor switching characteristics. Moreover, since the ferromagnetic film is formed on one surface, the resistance changes depending on the anisotropy of the magnetic resistance when saturated magnetization occurs, and the direction of the magnetic field within that surface can be detected.

In addition, since the first and second current paths made of ferromagnetic films are arranged in a nearly zigzag pattern, the impedance can be easily increased by narrowing the width without changing the thickness of the ferromagnetic film. Moreover, the total length of the current path can be made longer than lightning, and the impedance can be increased. Therefore,
The output voltage can be significantly increased, and an increase in power consumption can be suppressed.

Also, ρ7. ．． Since Δρ and ρ vary simultaneously depending on the temperature, Δρ and ρ. ;X? The degree change is extremely small, and the amount of output voltage change is almost unaffected.

Furthermore, while the sum of the resistance values of the first and second current paths is kept constant, each resistance value is changed according to the change in the direction of the magnetic field component, so the output voltage changes due to this change. The angle of the magnetic field can be determined based on m.

Furthermore, since an output terminal is provided at the connection point of the first and second current paths and a current supply terminal is provided at the other end, it becomes a three-terminal element, and one current supply terminal can be commonly grounded, and the peripheral circuit can be simplified.

Further, both ends of the plurality of strip elements of the first current path along the arrangement direction in which the plurality of strip elements of the first current path are sequentially arranged from the first current supply terminal side to the output one terminal side. The respective envelopes 35) of the sections are arranged substantially parallel to the strip elements of the second current path, and the strip elements of the second current path run from the second current supply terminal side to the output terminal side. The respective envelopes at both ends of the plurality of strip elements of the second current path along the arrangement direction that are sequentially arranged are substantially parallel to the strip elements of the first current path. Therefore, it is extremely easy to arrange a pair of current supply terminals to be separated from each other by an appropriate distance, and to arrange the current supply terminal and output terminal to be separated by an appropriate distance. It is possible to perform wiring processing extremely easily.

The first and second current paths each include a plurality of strip elements extending parallel to each other in a zigzag shape, and a plurality of connecting portions sequentially connecting these strip elements and extending parallel to each other. The strip elements of the first current path and the strip elements of the second current path are the same in number and are arranged to be substantially orthogonal to each other, and the connecting portion of the first current path and the strip element of the second current path are The strip elements of the current path are arranged to be substantially orthogonal to each other, and the connection portion of the second current path and the strip element of the second current path are arranged to be substantially orthogonal to each other. Both ends of the plurality of strip elements of the first and second current paths along the arrangement direction in which the plurality of strip elements are sequentially arranged from the first and second current supply terminal side toward the output terminal side. The respective envelopes of the sections are configured substantially parallel to the strip elements of the second and first current paths. Therefore, the first electricity? It is extremely easy to make the sum of the resistance of the Ji path and the resistance of the second current path exactly constant in the jJH% relationship, where &' is the angle of the field component.

[Brief explanation of drawings]

Figure 1 is a schematic principle diagram of the magnetoelectric conversion element of the present invention, Figure 2 is an equivalent circuit diagram of the element shown in Figure 1, Figure 3 is a plan view of a specific example of the magnetoelectric conversion element, and Figure 4 is the output voltage. A curve diagram showing the magnetic field angle dependence of the amount of change, and FIG. 5 is an equivalent circuit diagram showing a power supply system when three magnetoelectric conversion elements are connected in parallel. In the symbols used in the drawings, (1) is a magnetoelectric conversion element, (2) and (3) are current terminals, (4) is an output terminal, and A and B are ferromagnetic materials having magnetoresistive characteristics. Agent: Masaru Doatsu〃 Yoshio Tsunekami

Claims (1)

[Scope of Claims] (a) First and second ferromagnetic films each having an anisotropic magnetoresistive effect and provided on one surface of a substrate and connected in series to each other; a current path; (1)) an output terminal provided at a connection point connecting one end of each of the first and second current paths; (C) another end of each of the first and second current paths; a plurality of strip elements extending parallel to each other so that the first and second current paths each have a zigzag shape; The plurality of strip elements are sequentially connected and are made up of a plurality of connecting portions extending parallel to each other, and the strip elements of the first current path and the strip elements of the second current path are the same in number. and are arranged to be substantially perpendicular to each other, and the connecting portion of the first current path and the strip element of the first current path are approximately perpendicular to each other, and the connecting portion of the second current path and the strip element of the first current path are substantially perpendicular to each other. The strip elements of the current path are arranged to be substantially orthogonal to each other, and the plurality of strip elements of the first current path are arranged sequentially from the first current supply terminal side toward the output terminal side. Envelopes at both ends of the plurality of strip elements of the first current path along the arrangement direction are configured to be substantially parallel to the strip elements of the second current path, and The plurality of strip elements of the second current path are arranged sequentially from the second current supply terminal side toward the output terminal side at both ends of the plurality of strip elements of the second current path along the arrangement direction. stone)
is approximately parallel to the strip element of the first current path (1:\
In response to a change in the direction of the magnetic field component substantially parallel to the surface of the substrate, each of the resistance values of the first and second currents and the iI circuit changes while keeping the sum of the resistance values of the iI circuit constant. 1. A magnetoelectric transducer, characterized in that the magnetoelectric transducer is configured to detect a change in voltage at the output terminal due to the change in voltage.