JPH0140510B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetoelectric conversion element, and is particularly suitable for use in a detection mechanism for detecting a plurality of output waves having mutually different phases.

The present applicant previously proposed a magnetoelectric transducer having a novel structure in Japanese Patent Laid-Open No. 50-28989. First, the outline of the magnetoelectric conversion element according to the above application will be explained.

FIG. 1 shows the structure of this magnetoelectric transducer 10, in which the surface of a substrate 1 made of glass or the like has anisotropy of magnetoresistive effect like nickel-cobalt, that is, it has anisotropy of magnetoresistive effect depending on the direction of the magnetic field. Thin films of ferromagnetic materials A and B whose electrical resistance changes are formed. The ferromagnetic materials A and B can be formed by, for example, depositing a ferromagnetic material in a comb-teeth pattern or by depositing it on the entire surface and then etching it. These ferromagnetic materials A and B have a plurality of straight portions 2A, which serve as main current paths,
2B, and bent portions 3A, 3B connecting these, and the straight portions 2A, 2B
are arranged so as to be substantially orthogonal to each other. Further, the respective ends 4A and 4B of the straight portions 2A and 2B are connected to each other, and the ferromagnetic bodies A and B are connected in series. An output terminal 5 is formed at the connecting portion, and current terminals 7A, 7B are formed at the other ends 6A, 6B of the straight portions 2A, 2B, respectively.

FIG. 2 is a diagram showing the principle of operation, in which current terminals 7A and 7B are connected to a power source 8, and one current terminal 7B is grounded, forming a magnetoelectric conversion circuit 9 as a whole.

Now, apply a magnetic field H of sufficient strength to saturate magnetize the ferromagnetic materials A and B in the direction of the straight portion 2A of the ferromagnetic material A, that is, in the direction of the current in the plane formed by the ferromagnetic materials A and B. On the other hand, when the _{angle .theta} .

ρ _A = ρ⊥sin ² θ+ρ″cos ² θ … ρ _B =ρ⊥cos ² θ+ρ″sin ² θ … However, ρ⊥ is the value when ferromagnetic materials A and B are saturated magnetized in the direction perpendicular to the current. Similarly, the electrical resistance ρ'' of the ferromagnetic materials A and B is the electrical resistance of the ferromagnetic materials A and B when they are saturated magnetized in the direction parallel to the current.

Moreover, the voltage Vθ of the output terminal 5 is
are connected in series, so if the power supply voltage is _V0 , it can be expressed by the following equation.

Vθ=ρ _B /ρ _A +ρ _B V ₀ ... Substituting the formula into the equation and rearranging, Vθ=V ₀ /2−Δρ/2(ρ″+ρ⊥)・cos ² θ・V ₀
... (However, Δρ = ρ'' - ρ⊥.) In this equation, the first term on the right side represents the reference voltage, the second term represents the amount of change ΔVθ, and ΔV(θ) = Δρ/ It is expressed as 4ρ ₀ cos ² θ・V ₀ .... However, 2ρ ₀ = ρ″+ρ⊥, and ρ ₀ is the electrical resistance in the demagnetized state.

Therefore, the voltage Vθ at the output terminal 5 changes depending on the direction of the magnetic field H, and the output change is as shown in FIG.
It becomes a sine waveform with minimum values at 0° and 180° and maximum values at 90° and 270°.

Figure 4 shows the equivalent circuit, in which ferromagnetic material A,
It can be considered that B is a variable resistance whose resistance value changes depending on the direction of the magnetic field H.

When detecting rotation using such a magnetoelectric transducer 10, as shown in FIG.
This element 10 is arranged near the outer periphery of the rotor 11 to which S is magnetized, and changes in the lines of magnetic force due to the rotation of the rotor 11 are detected by this element 10. However, due to the rotation detection mechanism using such an element 10,
For example, in order to have a wavelength selection function, two output waves P whose phases are shifted by φ as shown in FIG.
When trying to detect Q, as shown in Figure 6,
Two elements 10 must be used separated by a predetermined distance l. At this time, if the interval between the magnetic pole patterns N or S is λ, then λ/l=180°/φ... That is, it can be seen that the spacing l between the elements 10 is closely related to the spacing λ of the magnetic pole patterns. Therefore, when designing such a rotation detection mechanism,
The arrangement of the element 10 must be determined by calculation from the spacing λ of the magnetic pole patterns. For example, if the spacing λ of the magnetic pole patterns differs because the diameter of the rotor 11 or the number of magnetized poles differs, The spacing l of the elements 10 must be changed each time. Also, element 10
is provided with a certain amount of clearance d from the rotor 11, so it was necessary to take this distance d into consideration. For example, if the clearances d of the two elements 10 are different from each other, the waveform of the resulting combined output wave may be distorted.

The present invention has been made to overcome the above-mentioned drawbacks, and aims to provide a magnetoelectric transducer that is independent of the spacing between magnetic pole patterns.

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 7 and 8.
This will be explained with reference to the figures.

As shown in FIG. 7, the magnetoelectric transducer 15 according to this embodiment has a first element part 16 and a second element part 1.
7 are formed so as to form a laminated structure. That is, on an oxide film 19 formed on the surface of a silicon substrate 18, a first element portion 16 made of a ferromagnetic material having anisotropy of magnetoresistive effect, such as Ni-Co, is formed.
are formed in a predetermined pattern, and furthermore, a second element portion 17 is also formed in a predetermined pattern on the upper surface thereof with an insulating layer 20 interposed therebetween. These first and second element parts 16 and 17 each have linear main current paths 21 and 22 and 23 and 24 connected by bending parts, respectively, similarly to the magnetoelectric conversion element 10 described above. At that time, the main current paths 21 and 22 and 2 in the first element section 16 and the second element section 17
The directions of 3 and 24 are perpendicular to each other. Furthermore, the first main current path 21 in the first element section 16 and the first main current path 23 in the second element section 17 are arranged at a predetermined angle with respect to each other, for example. Therefore, the second main current path 22 in the first element section 16 and the second main current path 24 in the second element section 17 are also tilted by φ. It's leaning. The first element section 16 and the second element section 17 are provided with output terminals 25, 26 and current terminals 27, 28, respectively, similarly to the magnetoelectric conversion element 10 described above.

That is, the magnetoelectric conversion element 1 configured as described above
5, each element portion 16, 17 has the same function as the magnetoelectric conversion element 10 described above.
Therefore, the same output waveform as shown in FIG. 3 is obtained from each output terminal 25, 26, and the first
The main current paths 21 and 22 of the element section 16 and the main current paths 23 and 24 of the second element section 17 are at an angle φ.
Since the output wave is tilted by φ, the phase of the output wave obtained is shifted by φ. In other words, it can be seen that the magnetoelectric transducer 15 of this example has exactly the same function as the two magnetoelectric transducers 10 arranged at a predetermined interval l as shown in FIG. Moreover, since the first element section 16 and the second element section 17 are stacked on top of each other, the phase shift φ is always constant regardless of the magnetic pole spacing of the rotor.

Next, an example of a method for manufacturing the magnetoelectric transducer 15 will be described with reference to FIGS. 8A to 8C.

As shown in FIG. 8A, first, the silicon substrate 18
An oxide film 19 is formed on the surface of the Ni-Co
A first element portion 16 consisting of the following is formed into a pattern by vapor deposition or the like. Next, as shown in FIG. 8B, a polyimide resin (trade name: PIQ, manufactured by Hitachi Chemical Co., Ltd.), for example, is coated on the upper surface as an insulating layer 20 under a curing condition of 120.
Apply at ℃×1h, 200℃×1h, 300℃×1h, etc.
Finally, as shown in FIG. 8c, a second element portion 17 also made of Ni--Co is formed in a pattern on the upper surface thereof by vapor deposition or the like. Actually 1
It is preferable to form several or more magnetoelectric transducers on a single silicon substrate, and after the above-mentioned steps are completed, to divide the magnetoelectric transducers into individual elements, thereby simultaneously manufacturing several or more magnetoelectric transducers.

Note that in this example, the first and second element portions 1
Although Ni-Co was used as 6 and 17, Insb etc. can also be used. Moreover, as the insulating layer 20,
Although SiO ₂ , Si ₃ N ₄ , ceramics, etc. can be used, the polyimide resin used in this example has the heat resistance (300°C or higher), surface flatness, chemical resistance, and It has excellent adhesion and can be said to be an advantageous material compared to thin films formed by vapor phase growth (SiO ₂ , Si ₃ N ₄ ), vapor deposition, sputtering, etc. as described above. Furthermore, in this example, an element pattern was formed on a silicon substrate, but transistors, diodes, ICs, etc. were formed within the substrate, and the elements were formed on the surface via an insulating layer (preferably _{a two} -layer SiO layer and a polyimide resin layer). It is also possible to form patterns. In this case, the transistor or the like on the substrate and the magnetoelectric conversion element may be connected with a commonly used conductive metal such as Al or Au through a contact hole provided in an insulating layer.

Furthermore, the magnetoelectric transducer 15 according to this embodiment has the following advantages. That is, in the magnetoelectric transducer 15 of this embodiment, the first element portion 16 and the second
The element parts 17 are stacked on each other with an insulating layer 20 in between, and the main current paths 21 and 2 of both the element parts 16 and 17 are
2, 23, and 24 substantially completely overlap each other in substantially parallel planes. Therefore, for example,
The distance (clearance) d of each element part 16, 17 from the rotor etc. is equalized, and there is no output difference between the two element parts 16, 17 depending on the positional relationship, so a synthesized output wave without distortion can be obtained. . Also, element 1
The overall size of 5 can be reduced, and costs can be reduced. Furthermore, since the first element section 16 is covered with the insulating layer 20, disconnection thereof can be effectively prevented, and the element pattern can be protected from oxidation and the like. Moreover, each element part 1
Main current paths 21, 22 and 2 in 6, 17
3 and 24 exist in planes that are substantially parallel to each other, so when a magnetic field is applied parallel to the substrate 18, the magnetic field is uniformly applied to each element portion 16 and 17.
Therefore, the variation in the output characteristics is reduced, and the distortion of the resulting combined output wave is also reduced.

Although the present invention has been described above with reference to one embodiment, the above embodiment does not limit the present invention in any way, and various changes can be made based on the technical idea of the present invention. For example, the main current paths 21 and 22 of the first element section 16 and the main current path 2 of the second element section 17
The slope φ between 3 and 24 can be selected to a desired value. In addition, this slope φ was sequentially changed 3
It is also possible to stack three or more element parts, and in this case, three or more output waves having respective phase differences can be obtained. Furthermore, if the magnetic field strength is strong and the magnetic flux density becomes uneven depending on the location, the main current paths 21 and 22 of the first element section 16 and the main current path 23 of the second element section 17 24, that is, a structure in which all the main current paths are stacked can be used.

As explained above, the magnetoelectric transducer according to the present invention is made of a ferromagnetic material whose electrical resistance changes depending on the direction of the magnetic field, and which are arranged in a perpendicular direction and connected in series. A plurality of element parts having first and second main current paths are stacked with the directions of the corresponding main current paths set at a predetermined angle with respect to each other. Therefore, an output wave having a desired phase difference can be obtained regardless of the magnetic pole pattern of the rotor, etc., and therefore it can be used for various magnetic pole patterns. Further, since there is no need to take into account the variation in clearance from, for example, the rotor, the handling becomes easier. Furthermore,
The size of the entire element can be reduced, and costs can be reduced.

[Brief explanation of drawings]

Fig. 1 is a plan view showing the structure of a conventional magnetoelectric conversion element, Fig. 2 is its principle circuit diagram, Fig. 3 is an output voltage waveform diagram, Fig. 4 is an equivalent circuit diagram, and Fig. 5 shows that the phase is φ.
FIG. 6 is an output voltage waveform diagram similar to FIG. 3 showing two output waves shifted by a certain amount, and FIG. 6 is a schematic plan view showing the arrangement of a conventional magnetoelectric transducer for obtaining the output shown in FIG. FIG. 7 is an exploded perspective view showing the structure of a magnetoelectric conversion element according to an embodiment of the present invention, and FIG. 8 shows a method for manufacturing this magnetoelectric conversion element in order of steps.
The figure is a schematic sectional view showing a state in which a first element portion is formed on a substrate, FIG. 8B is a schematic sectional view similar to FIG. 8A showing a state in which an insulating layer is formed thereon, and FIG.
FIG. C is a schematic sectional view similar to FIG. 8A, showing a state in which a second element portion is further formed thereon. In addition, in the symbols used in the drawings, 15
...Magnetoelectric conversion element, 16...First element portion, 17
...Second element section, 21, 22, 23, 24...
This is the main current path.

Claims (1)

[Claims] 1. At least two element parts are made of a ferromagnetic material whose electrical resistance changes depending on the direction of the magnetic field, and have first and second main current paths connected in series and arranged at right angles to each other. , a magnetoelectric conversion element characterized in that the elements are laminated in such a manner that the directions of the corresponding main current paths are mutually inclined at a predetermined angle.