JP2001227985A - Magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic head allowing suppression of variation in surface magnetic flux density in the magnetic head. SOLUTION: In this magnetic head, plural semiconductor magnetoresistive elements 8 each formed with semiconductor magnetoresistive films 12 on a semiconductor substrate 11 are disposed on a mounting face 6a formed in a permanent magnet 6. The semiconductor magnetoresistive element 8 is disposed on the mounting face 6a of the permanent magnet 6 such that the mounting face 6a of the permanent magnet 6 faces a non-formation surface of the semiconductor magnetoresistive films 12, while a ferromagnetic substance 16 is disposed between the non-formation surfaces of the semiconductor substrates 11 and the mounting face 6a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a magnetic head for detecting rotation and movement of an object using a semiconductor magnetoresistive element.

[0002]

2. Description of the Related Art For example, a semiconductor magnetoresistive element using a magnetic conversion function has been used for detecting rotation and displacement of an object. As the semiconductor magnetoresistive element, those using indium antimony (InSb) having a large detection output as a semiconductor magnetoresistive film are often used, and an object to be detected made of a magnetic material, for example, a rotation detecting device for detecting rotation of a gear. Used in magnetic heads.

In this magnetic head, first and second semiconductor magnetoresistive elements each having a semiconductor substrate made of a high-resistance material such as silicon on a permanent magnet are formed on a thermosetting adhesive. It is configured by arranging through.
The magnetic head connects the first and second semiconductor magnetoresistive elements in series, takes out the midpoint of each semiconductor magnetoresistive element, and detects the midpoint potential to rotate the object to be detected. This is to detect movement.

[0004]

Such a magnetic head is,
The surface magnetic flux density of the permanent magnet varies depending on whether the mounting surface of the permanent magnet on which the semiconductor magnetoresistive elements are arranged is not necessarily flat or the material of the permanent magnet. Therefore, this variation in surface magnetic flux density
Variations in element characteristics of the semiconductor magnetoresistive element, that is, variations in the intermediate potential, occur. The variation in the intermediate potential is corrected by, for example, an adjustment resistor of a trimming resistor, but the manufacturing process is complicated.

Accordingly, the present invention is directed to a magnetic head capable of suppressing variations in surface magnetic flux density in a magnetic head, focusing on the above-described problems.

[0006]

According to the present invention, a plurality of semiconductor magnetoresistive elements each having a semiconductor magnetoresistive film formed on a substrate are arranged on a mounting surface provided on a permanent magnet. A magnetic head, wherein the semiconductor magnetoresistive element is disposed on the mounting surface of the semiconductor substrate such that a surface on which the semiconductor magnetoresistive film is not formed and a mounting surface of the permanent magnet face each other. In addition, a ferromagnetic material is provided between the non-formation surface of the semiconductor substrate and the mounting surface.

The ferromagnetic material is smaller than the mounting surface of the permanent magnet and is disposed substantially at the center of the mounting surface.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, for example, a rotation detecting device A includes a case 1, a magnetic head 2, and a hard circuit board 3.
And an electric cord 4.

The case 1 is made of PBT (polybutylene terephthalate) or PPS (polyphenylene sulfide).
Of the rotation detecting device A, which has a detection surface (bottom) 1a for detecting unevenness of a gear 5 such as a transmission gear serving as an object to be detected in the vehicle. To store.

The magnetic head 2 includes a permanent magnet 6, a magnet holder 7, a semiconductor magnetoresistive element 8, a flexible circuit board 9, and a ferromagnetic material to be described later.

The magnetic head 2 has a permanent magnet 6 disposed in a recess 7a of a magnet holder 7 made of a resin material in a state in which a part of the cylindrical permanent magnet 6 projects. A ferromagnetic material (to be described later) and a semiconductor magnetoresistive element 8 are sequentially arranged on a mounting surface 6a serving as an upper flat portion, and an element electrode to be described later formed on a magnetic detection surface 8a of the semiconductor magnetoresistive element 8 And the flexible circuit board 9 are electrically connected.

The hard circuit board 3 is made of a hard material such as a resin containing glass fiber. The hard circuit board 3 has a predetermined wiring pattern on the front and back surfaces, and a land provided at a predetermined position of the wiring pattern is used to amplify the output from the semiconductor magnetoresistive film 8 or absorb external noise. Are mounted, and the flexible circuit board 9 is connected and fixed. A magnet holder 7 is disposed on the gear 5 side of the hard circuit board 3. The magnet holder 7 is configured such that the magnetic detection surface 8 a of the semiconductor magnetoresistive film 8 is on the detection surface 1 a of the case body 1. It is arranged on the rigid circuit board 3 so as to follow.

The electric cord 4 is for supplying power to the semiconductor magnetoresistive element 8 and for outputting an output signal from the semiconductor magnetoresistive element 8 to the outside.

Next, the magnetic head 2 will be described in detail with reference to FIGS.

The magnetic head 2 has first and second rectangular shapes.
Semiconductor magnetoresistive elements 8a and 8b (8).

Each semiconductor magnetoresistive element 8a, 8b is a semiconductor substrate (for example, silicon (Si)) made of a high-resistance material.
11 on the surface side, indium (In) and antimony (Sb)
Is formed in a predetermined shape including
On the semiconductor magnetoresistive film 12, for example, a metal thin film having a two-layer structure of chromium (Cr) or copper (Cu) is used to form an element electrode (extraction electrode for extracting to the outside) 13 for extracting an electric signal and a resistance value adjustment. Forming a short-circuit electrode 14 for
A protective film 15 made of an insulating material such as polyimide is formed on the semiconductor substrate 11 so that a part of the device electrode 13 is exposed to the outside.
Covered in. Incidentally, each semiconductor magnetoresistive element 8a, 8b
Has a two-terminal structure in which the device electrodes 13 are formed on one side of the semiconductor substrate 11 respectively.

The magnetic head 2 has a mounting surface 6a on which the permanent magnet 6 is mounted.
Iron (Fe) or nickel (Ni) between the semiconductor substrate 11 (the side of the semiconductor substrate 11 where the semiconductor magnetoresistive film 12 is not formed) of the semiconductor magnetoresistive elements 8a and 8b.
A ferromagnetic body 16 having a circular shape is formed.

The ferromagnetic body 16 is a plate-like member in which the periphery of the ferromagnetic body 16 is smaller than the mounting surface 6a located inside the circumference of the mounting surface 6a of the permanent magnet 6, and is substantially the same as the mounting surface 6a. It is arranged in the center.

In the magnetic head 2, the flexible circuit board 9 is electrically fixed to the element electrodes 13 of the semiconductor magnetoresistive elements 8a and 8b.
a, 8b and the ferromagnetic material 16 and the ferromagnetic material 16 and the permanent magnet 6 are bonded and fixed via a thermosetting adhesive, respectively, and the permanent magnet 6 is disposed in the magnet holder 7. .

The magnetic head 2 has a two-terminal structure in which each element electrode 13 located inside each of the semiconductor magnetoresistive elements 8a and 8b is connected via a flexible circuit board 9, so that each semiconductor magnetoresistive element 8a and 8b are connected in series, a predetermined drive voltage Vin is applied to each element electrode 13 located outside, and the resistance value change of each semiconductor magnetoresistive element 8a and 8b accompanying the change of the bias magnetic field due to the rotation of the gear 5 Is taken out as an intermediate potential Vout to detect the rotation of the gear 6.

A feature of the magnetic head 2 is that a ferromagnetic material 16 is provided between each of the semiconductor magnetoresistive elements 8a and 8b and the permanent magnet 6.

Therefore, the magnetic head 2 is used when the mounting surface 6a of the permanent magnet 6 on which the semiconductor substrate 1 is disposed is not flat or when the surface magnetic flux density of the permanent magnet 6 varies due to the material of the permanent magnet 6. Even if there is, the variation of the surface magnetic flux density can be averaged, so that the variation of the intermediate potential Vout which is the output of each of the semiconductor magnetoresistive elements 8a and 8b can be suppressed, and the intermediate potential Vout which is troublesome in the manufacturing process. (Adjustment by trimming resistance) can be simplified. In addition, with the simplification of the adjustment process of the intermediate potential Vout, the adjustment accuracy of the intermediate potential Vout can be improved, and the rotation detection device A that can accurately detect rotation can be provided.

The magnetic head 2 focuses on the fact that the surface magnetic flux density is small at the peripheral portion and the surface magnetic flux density is large at the center of the permanent magnet 6, and the ferromagnetic material 16 is attached to the mounting surface 6a of the permanent magnet 6 on the permanent magnet 6. Since it is smaller and is disposed substantially at the center of the mounting surface 6a, the average value of the surface magnetic flux density can be improved, so that the intermediate potential Vout can be favorably obtained.

In the embodiment of the present invention, the ferromagnetic material 1
Although the magnet 6 is smaller than the mounting surface 6a of the permanent magnet 6, in the present invention, even if the ferromagnetic material 16 and the permanent magnet 6 have substantially the same diameter, the average of the surface magnetic flux density is obtained. And the variation of the intermediate potential can be suppressed.

Further, in the embodiment of the present invention, the ferromagnetic body 16 is formed in a circular shape, but may be, for example, a square shape, and the shape of the ferromagnetic body in the present invention can be arbitrarily changed. .

[0027]

According to the present invention, there is provided a magnetic head in which a plurality of semiconductor magnetoresistive elements each having a semiconductor magnetoresistive film formed on a substrate are arranged on a mounting surface provided on a permanent magnet. The non-formation surface of the semiconductor magnetoresistive film and the semiconductor magnetoresistive element are arranged on the placement surface so that the placement surface of the permanent magnet faces the placement surface, and the non-formation surface of the semiconductor substrate. A ferromagnetic material is disposed between the mounting surface and the mounting surface, and a mounting surface for mounting the semiconductor substrate in the permanent magnet is not flat or a material of the permanent magnet, and the like. Even if the surface magnetic flux density of the permanent magnet varies, the variation of the surface magnetic flux density can be averaged, so that the variation of the intermediate potential which is the output of the semiconductor magnetoresistive element is suppressed. Bets can be, it is possible to simplify the adjustment process of bothersome of the intermediate potential in the manufacturing process.

Further, the ferromagnetic material is smaller than the mounting surface of the permanent magnet and is disposed substantially at the center of the mounting surface, and improves the average value of the surface magnetic flux density. Therefore, the intermediate potential can be obtained favorably.

[Brief description of the drawings]

FIG. 1 is an essential part cross-sectional view showing a rotation detection device according to an embodiment of the present invention.

FIG. 2 is an essential part cross sectional view showing the magnetic head of the embodiment;

FIG. 3 is a plan view showing the magnetic head of the embodiment.

[Explanation of symbols]

 Reference Signs List 2 magnetic head 6 permanent magnet 6a mounting surface 7 magnet holder 7a recess 8 semiconductor magnetoresistive element 8a first semiconductor magnetoresistive element 8b second semiconductor magnetoresistive element 9 flexible circuit board 11 semiconductor substrate 16 ferromagnetic material

Claims (2)

[Claims] 1. A magnetic head in which a plurality of semiconductor magnetoresistive elements each having a semiconductor magnetoresistive film formed on a substrate are disposed on a mounting surface provided on a permanent magnet, wherein the semiconductor magnetoresistive film on the semiconductor substrate is provided. The semiconductor magnetoresistive element is arranged on the mounting surface such that the non-forming surface of the permanent magnet faces the mounting surface of the permanent magnet, and the non-forming surface and the mounting surface of the semiconductor substrate are arranged on the mounting surface. Wherein a ferromagnetic material is disposed between the magnetic head and the magnetic head. 2. The magnetic head according to claim 1, wherein the ferromagnetic material is smaller than the mounting surface of the permanent magnet, and is disposed substantially at the center of the mounting surface.