JPH0241871Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Field of industrial application) The invention is a ferromagnetic magnetoresistive element that utilizes the magnetoresistive effect of a ferromagnetic material, and is particularly suitable for detecting the rotational speed of a rotating body. The present invention relates to a ferromagnetic magnetoresistive element.

(Prior art) Ferromagnetic magnetoresistive elements utilize the phenomenon that the electrical resistance of a ferromagnetic material changes when a magnetic field is applied to it. It is widely used because it has the advantage of being able to be controlled by As shown in FIG. 3, this type of ferromagnetic magnetoresistive element generally has meandering sides 1a and 2 whose directions are orthogonal to each other.
A first current path 1 and a second current path 2 made of a thin film-like ferromagnetic material each having a are arranged on a substrate 3, and these current paths 1 and 2 are connected in series. has been done. In the ferromagnetic magnetoresistive element A configured in this manner, a direct current is passed between the terminals a and b at both ends of each current path 1 and 2, and the common connection point of each current path 1 and 2 is It is used as a differential type in which the output voltage is obtained between the terminal c and the ground terminal provided on the ground terminal. Further, in this case, the resistance values of the first and second current paths 1 and 2 become maximum when lines of magnetic force parallel to each meandering side 1a and 2a interlink with each other, and each meandering side 1a , 2a are interlinked with the lines of magnetic force perpendicular thereto. Therefore, the output voltage of the ferromagnetic magnetoresistive element A is minimized when the line of magnetic force to be detected is on one of the meandering sides 1a, 2a. It is maximum when parallel to one and perpendicular to the other.

(Problems to be solved by the invention) When detecting the circulation number of a rotating body using the ferromagnetic magnetoresistive element A having the above configuration, as shown in FIG. A multi-pole magnetized annular permanent magnet 4 is attached, and a ferromagnetic magnetoresistive element A is placed at a position that receives the magnetic flux from this permanent magnet 4. At this time, the permanent magnet 4
The lines of magnetic force from the ferromagnetic magnetoresistive element A are interlinked with each other as shown in FIG. As is clear from FIG. 6, when the magnetic pole pitch of the permanent magnet 4 is sufficiently larger than the arrangement pitch of the first and second current paths 1 and 2, the lines of magnetic force from the permanent magnet 4 ( ) are each meandering side portion 1a, 2a
(It becomes parallel to one side and perpendicular to the other side as shown in FIG. 3, so a large output voltage can be obtained.

However, in recent years, in order to increase the resolution of rotation speed detection, it has been considered to magnetize the annular permanent magnet 4' attached to the rotating body to be detected to have more poles as shown in FIG. There is. However, when the magnetization pitch of the permanent magnet 4' becomes smaller than the arrangement pitch of the first and second current paths 1 and 2, the relative positional relationship between the permanent magnet 4 and the ferromagnetic magnetoresistive element A becomes As shown in Figure 7, which shows two examples, the lines of magnetic force from the permanent magnet 4' (indicated by the two-dot chain line)
Since the directions of interlinkage with respect to each of the meandering sides 1a and 2a (see FIG. 3) are substantially the same, there is a problem in that the output voltage decreases. In order to deal with such problems, it is sufficient to secure the effective length of each meandering side portion 1a, 2a and then reduce the size of the first and second current paths. In practice, it is extremely difficult to do so, and in the past, the situation was that the output voltage decreased as described above.

The present invention was developed in view of the above circumstances, and its purpose is to be able to obtain a large output voltage with a simple configuration even when the detected magnetic pole pitch is set small in order to increase the detection resolution. The object of the present invention is to provide a ferromagnetic magnetoresistive element that exhibits the following effects.

[Structure of the invention] (Means for solving the problem) The present invention provides a first current path and a second current path made of a ferromagnetic material formed in a meandering shape, which are disposed on a substrate. The present invention is intended for a ferromagnetic magnetoresistive element in which a current flows in series with each current path and an output voltage is obtained from a common connection point of each current path, and the first and second The current paths are parallel to each other, and each meandering side portion of the first and second current paths is formed in a curved shape along a parabola.

(Operation) The first and second current paths formed in a meandering shape are parallel to each other, and each meandering side of the first and second current paths is formed in a curved shape along a parabola. When the detected magnetic pole pitch is set small, the lines of magnetic force from the detected magnetic poles become parallel to one of the current paths and orthogonal to the other, thereby obtaining a large output voltage. Can be done.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, reference numeral 5 denotes a rectangular substrate made of an insulating material. On this substrate 5, a first current path 6 and a second current path are formed by forming a thin film of ferromagnetic material in a meandering shape. 7 are attached parallel to each other,
A ferromagnetic magnetoresistive element 8 is thus constructed.
In this case, each meandering side portion 6a and 7a of the first and second current paths 6 and 7 is formed in a curved shape along a parabola. Further, the first and second current paths 6 and the seventh are connected in series, and input terminals 8a and 8b are formed at both ends thereof, and an output terminal 8c is formed at the common connection point. The ferromagnetic magnetoresistive element 8 has an input terminal 8
Output terminal 8 with direct current flowing between a and 8b
It is configured as a differential type in which the output voltage is obtained between the C and ground terminals.

Ferromagnetic magnetoresistive element 8 configured in this way
For example, as shown in FIG.
When detecting the magnetic flux from a permanent magnet 9 that is magnetized with multiple poles to improve detection resolution like the permanent magnet 4' shown in the figure, the lines of magnetic force from the permanent magnet 9 (see the two-dot chain line) are parabolic. Due to the fact that
It becomes parallel to one of the meandering sides 6a and 7a (see Figure 1) and perpendicular to the other, and as a result, a large output voltage can be obtained between the output terminal 8c and the ground terminal. can. However, in FIG. 2, two examples of the relative positional relationship between the permanent magnet 9 and the ferromagnetic magnetoresistive element 8 are shown.

[Effects of the invention] According to the invention, as is clear from the above description, the first current path and the second current path formed of a ferromagnetic material in a meandering shape are arranged on a substrate. In a ferromagnetic magnetoresistive element in which a current is caused to flow in series with each of these current paths, and an output voltage is obtained from a common connection point of each of the current paths,
This has the practical effect of being able to obtain a large output voltage with a simple configuration even when the detected magnetic pole pitch is set small in order to improve the detection resolution.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, with FIG. 1 being an overall plan view and FIG. 2 being a plan view showing the actual usage state. In addition, FIGS. 3 to 7 are for explaining the conventional example, and FIG. 3 is a view equivalent to FIG. 1, FIGS. 4 and 5 are perspective views showing actual usage conditions, and FIG. and FIG. 7 are views corresponding to FIG. 2. In the figure, 5 is a substrate, 6 is a first current path, 7 is a second current path, 6a and 7a are meandering sides, and 8 is a ferromagnetic magnetoresistive element.

Claims (1)

[Scope of utility model registration request] A first current path and a second current path made of a ferromagnetic material formed in a meandering shape are arranged on the substrate, and a current is passed in series to each of these current paths, and a common current path of each of the current paths is In a ferromagnetic magnetoresistive element that obtains an output voltage from a connection point, the first and second current paths are configured to be parallel to each other, and each meandering of the first and second current paths is configured to be parallel to each other. A ferromagnetic magnetoresistive element characterized in that a side portion is formed in a curved shape along a parabola.