JPH0756508B2 - Magnetic detector - Google Patents

Description

The present invention relates to a magnetic detector utilizing a magnetoresistive effect,
Particularly, it relates to a configuration for increasing the detection output.

[Conventional technology]

FIG. 5 is a plan view showing a pattern configuration of a conventional magnetic detector, and FIG. 6 is a sectional view of the magnetic detector.

A magnetic ribbon 3 such as permalloy (Fe-Ni) is deposited on an insulating layer 2 formed of an oxide film such as SiO ₂ formed on a substrate 1 such as Si. This magnetic ribbon 3 is formed into a serpentine pattern 3p as shown in FIG. 5 by using a usual lithography technique. After that, heat treatment is performed in a magnetic field in order to impart uniaxial magnetic anisotropy in the longitudinal direction of the magnetic ribbon 3. Next, the adhesion layer 4 made of Ti, Cr or the like and the conductive thin strip 5 of Au are obliquely deposited at regular intervals to form a so-called barber pole pattern. At this time, the lead pattern 7 for establishing electrical connection with the outside is also produced at the same time. Finally, the magnetic detector is completed by fixing it to the lead frame by soldering or bonding and sealing it with the protective resin 6.

In such a magnetic detector, the direction of magnetization is parallel to the zigzag pattern as indicated by M, but when an external magnetic field Hex was applied in a direction perpendicular to this, it was initially parallel to the pattern. The magnetization M gradually increases as the external magnetic field Hex increases, and when a strong magnetic field is applied, the magnetization Hs in the same direction as the external magnetic field Hex is finally obtained.

FIG. 7 is a diagram showing the relationship between the magnetization direction M and the magnetoresistive effect at this time. The angle θ formed by the magnetization direction M by the external magnetic field Hex with respect to the current i flowing in the zigzag pattern as shown in (a). However, as in (b), from 0 degree to π / 4 → π / 2 → π
When it increases from 3/4 → π ..., the magnetoresistive effect shows the maximum value when the angle θ formed by the magnetization direction M and the current i is 0 ° and 180 °, that is, parallel to each other. At 90 degrees, that is, at right angles to each other, the minimum magnetoresistance effect is obtained.
The linearity is best at the intermediate values of 45 degrees, 135 degrees, 225 degrees, and 315 degrees, and the output changes linearly with respect to the external magnetic field Hex.

Therefore, in order to incline the conductive ribbon 5 at 45 degrees as shown in FIG.
As indicated by the arrow, the magnetic flux flows at an angle of 45 degrees with respect to the magnetization direction M. Therefore, it is possible to accurately output the change in the external magnetic field Hex at the position with the best linearity.

[Problems to be solved by the invention]

However, in the conventional detector formed by arranging the conductive ribbon 5 on the magnetic ribbon 3 which is thus folded in a zigzag manner by about 45 degrees,
As shown in FIG. 5, a portion Pa where the conductive ribbon 5 is formed and a return portion Pb where the conductive ribbon 5 is not formed are alternately connected.

In this configuration, there is a drawback that the return portion Pb deteriorates the linearity between the measurement magnetic field and the output.

On the other hand, as described in Japanese Patent Application Laid-Open No. 57-107088, by alternately stacking ferromagnetic films and insulating layers and alternately connecting the ferromagnetic films at both ends, the cross-sectional structure becomes a zigzag shape. As described in JP-A-59-9987, a method of forming unevenness on the substrate surface and forming a film having a magneto-resistive effect thereon is also proposed. However, if the ferromagnetic films are laminated or uneven, the characteristics may deteriorate due to distortion.

The technical problem of the present invention is to solve the above problems in the conventional magnetic detector, and to make it possible to form a conductive ribbon on all magnetic ribbons of the zigzag fold, thereby increasing the detection output and increasing the efficiency. It is to realize a good magnetic detector, to prevent the characteristics from being deteriorated by distortion, and to easily manufacture the magnetic detector.

[Means for Solving the Problem] The technical means according to the present invention taken to solve this problem is that a conductive ribbon is provided at regular intervals on a magnetic ribbon having uniaxial magnetic anisotropy in the longitudinal direction. A magnetic detector for detecting magnetism by a magnetoresistive effect, wherein the magnetic ribbon is formed in a flat surface, and the internal magnetism is aligned in the same direction in advance. The direction of internal magnetization and the flowing current are about π / 4 (or 7 / 4π)
The part where the conductive ribbons are obliquely arranged so as to form the angle of and the part where the conductive ribbons are obliquely formed so as to form approximately 5 / 4π (or 3 / 4π) are folded into a zigzag shape. It is connected alternately, and each folded-back portion of the zigzag-shaped pattern is formed by bending twice at a right angle.

[Action]

Also in the present invention, in the outward path of the zigzag folded pattern, the magnetic detection effect by the magnetoresistive effect is the same as the conventional, but in the present invention, in the return path of the zigzag folded pattern, the same as the outward path. A barber pole-shaped pattern is formed by arranging the conductive ribbons obliquely, and the magnetic detection function is performed. Further, since the magnetic detection outputs in both the reciprocating direction are formed so as to be superposed, a higher output than the conventional one can be obtained.

In addition, the magnetic ribbon is formed in a flat surface, and each folded portion of the zigzag pattern is also formed by bending twice at a right angle in the same surface, which facilitates manufacturing and causes distortion. There is no fear of characteristic deterioration.

〔Example〕

Next, practical examples of how the magnetic detector according to the present invention is embodied will be described. FIG. 1 is a plan view showing a pattern configuration of a magnetic detector according to the present invention. The cross-sectional structure of the magnetic detector is the same as the conventional one, and has the same layer structure as in FIG. In the pattern configuration of the present invention, as shown in FIG. 1, the oblique conductive thin strip 5 on the zigzag folded magnetic thin strip 3 is provided not only on the outward path Pa of the zigzag folding pattern but also on the return path Pb with the same inclination, and thus the zigzag folding is performed. A barber pole-like pattern is formed in all of the parallel portions of the.

That is, according to the present invention, the angle (θ ₁ ) formed by the current i flowing through the conductive ribbon 5 in the direction of the magnetization M applied parallel to the zigzag magnetic ribbon 3 is π / 4 + nπ (or 7 / 4π-nπ). ) (N
= 0, 1), the output is increased by paying attention to the fact that the magnetic resistance ρ has the same relationship.

Now, as shown in FIG. 2 (a), it has uniaxial magnetic anisotropy.
By applying an in-plane magnetic field Hex to the magnetic ribbon 3 at right angles.
The magnetization M from the easy axis θ₁If it rotates,It is represented by. Where Hs is required to saturate the magnetization
Magnetic field According to Fig. 2 (a), current i and magnetization M
The angle θ isTherefore, the magnetic resistance ρ (= ρ_⊥+ Δρm (1-sin²θ) (2) (ρ , Ρ_⊥: When the magnetization M is saturated parallel to the current i
Resistance value and resistance value when magnetized perpendicularly Δρm = ρ −
ρ_⊥) IsIt is represented by.

here However, the equation (2) is converted into the equation (3).

Therefore, it can be seen that if the angle formed by the current i and the magnetization M has the relationship of (1) or (4), the magnetic resistance ρ exhibits the same value.

A similar relationship is In other words, the same holds for negative elements as shown in FIGS. 2B and 3.

The embodiment shown in FIGS. 1 and 2 (a) is an example in which the current flows in the directions of π / 4 and 5 / 4π with respect to the direction of the magnetization M. As is clear from the above equation, It is obvious that the same effect can be obtained even in the case of flowing in the directions of 7 / 4π and 3 / 4π as shown in FIGS. 2 (B) and 3.

As shown in FIG. 4, using the magnetic detection element in which the conductive ribbons are obliquely arranged in both of the zigzag-shaped reciprocation as described above,
A high-sensitivity magnetic detector can be realized by assembling the element in a bridge and measuring the potential difference between both output terminals.

〔The invention's effect〕

Thus, in the detector constructed according to the method of the present invention, the output voltage can be made higher than the conventional one because the magnetic detection effect by the magnetoresistive effect is performed even in the return path of the zigzag-shaped magnetic ribbon. Is also improved, and the effect is extremely large. In addition, since the magnetic ribbon is formed in a flat surface, and each folded portion of each zigzag-shaped conductive ribbon is formed by bending twice at a right angle in the same surface, it is easy to manufacture. There is no fear of deterioration of characteristics due to distortion.

[Brief description of drawings]

1 is a plan view showing an embodiment of a magnetic detector according to the present invention, FIG. 2 is a view showing characteristics of an element, FIG. 3 is a plan view showing another embodiment, and FIG. 4 is a magnetic view of the present invention. FIG. 5 is a circuit diagram of a magnetic detection device using a detector, FIG. 5 is a plan view of a conventional magnetic detector, FIG. 6 is a sectional view thereof, and FIG. 7 is a diagram showing a magnetic detection action. In the figure, 3 is a magnetic ribbon, 5 is a conductive ribbon, Pa is the outward path of the zigzag pattern, and Pb is the return path of the zigzag pattern.

Claims (1)

[Claims] 1. A magnetic detector in which conductive ribbons are arranged at regular intervals on a magnetic ribbon having uniaxial magnetic anisotropy in the longitudinal direction, and the magnetism is detected by a magnetoresistive effect. The ribbon is formed on a flat surface, and the internal magnetization is aligned in the same direction beforehand. The direction of the internal magnetization and the flowing current are about π / 4 (or 7 / 4π).
The part where the conductive ribbons are obliquely arranged so as to form the angle of and the part where the conductive ribbons are obliquely formed so as to form approximately 5 / 4π (or 3 / 4π) are folded into a zigzag shape. A magnetic detector characterized in that they are alternately connected, and that each of the folded portions of the zigzag folded pattern is formed by bending twice at a right angle.