JPS5932035Y2 - magnetic head core - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improved structure of a head core as a component of a magnetic head.

Conventionally, magnetic head cores have been constructed from metallic magnetic materials such as Sendust alloy or oxide magnetic materials such as ferrite.

In general, metal magnetic materials have lower specific resistance than oxide magnetic materials, so special measures must be taken to minimize eddy current loss.

For this reason, in conventional magnetic heads made of metal magnetic materials, several thin pieces of metal magnetic material are laminated and an insulating layer is interposed between the layers to prevent the eddy current loss from increasing.

However, such conventional magnetic heads have the following problems.

(1) When laminating thin metal magnetic material pieces, strict dimensional accuracy is required for each material piece, which increases the manufacturing cost.

In particular, it is currently not easy to thin a material as hard as sendust alloy with high precision.

(2) When several magnetic thin pieces are laminated, uneven wear occurs in the laminated parts, and powdery foreign matter from the magnetic tape adheres to the laminated parts, resulting in deterioration of sound quality during recording and playback. The frequency characteristics are unstable.

The purpose of this invention is to provide a novel magnetic rad core that solves the problems of the prior art described above.

The magnetic head core according to this invention includes: (a) a butting core member made of a plate-shaped metal magnetic material having a pair of main surfaces facing each other, and between both end portions, each scheduled abutting portion is formed in the thickness direction; (b) a thin piece made of permalloy or ferrite inserted into the notch grooves; (c) the notches; An insulating layer is provided between the inner surface of the groove and the thin piece.

According to the structure of this invention, since the tip of the head core is made of a solid magnetic material, good and stable frequency characteristics can be obtained, and the middle part of the head (coil winding part) which makes a large contribution to the head characteristics V. ) has a substantially laminated shape, so it is possible to suppress the occurrence of eddy current loss in the coil winding portion.

Further, since the rear end portion of the head core is also structured to remain continuous in the thickness direction, when a plurality of -7J cores are butted, a large butting area can be obtained, which has the advantage of making it easier to butt.

In manufacturing the magnetic head core of this invention, a wire saw or other simple mechanical means can be used for cutting the grooves, and high dimensional accuracy is not required in the case of laminating thin pieces, making it possible to significantly reduce costs.

Further, since a core lamination step is not necessary when assembling the head, the number of assembly steps can be reduced.

Embodiments of this invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the top structure of a magnetic head according to an embodiment of this invention, and FIGS.
This figure shows a cross section taken along the line ■-■, where A shows the state in which the cut groove is formed, and B shows the state in which a thin piece or the like is inserted into the cut groove.

As shown, the magnetic head 10 includes two core members 12 and 22 that are abutted against each other with a predetermined gap between them.

Each of these core members 12 and 22 has a pair of main surfaces facing each other (two surfaces corresponding to the front and back in the paper of FIG. 1).
It is a plate-like material having a substantially U-shaped planar shape, for example, 9.6% Si -5.4% A7
It is made of a sendust alloy with a composition of -8.5% Fe.

The core members 12, 22 have respective distal ends 14°24.
and abutting portions 14a, 1 continuous in the thickness direction as illustrated in FIG. 2A at the respective rear end portions 16.26.
6a are formed respectively.

In addition, the core members 12, 22 have grooves 1d parallel to the main surfaces between the leading ends 14, 24 and the rear ends 16, 26, as illustrated in FIG. 2A. As illustrated in FIG. 2B, a thin piece 21 made of permalloy or ferrite is inserted into each of the cut grooves 18 through an insulating layer 19.

In addition, in FIG. 1, 18a, 18b, 28a, 28
b indicates the terminal end of the cut groove, A indicates the tip 1
4,24 and the rear end 16,26.

FIG. 2A shows the cut groove 1 for one core member 12.
8, the width d of the cut groove portion 18 can be approximately 0.1 to 0.2 mm.

In this way, the butt portions 14a, 16 at both ends of the core member
The cut groove portion 18 is cut so that a remains continuous in the thickness direction.
When formed, both core members 12, as shown in FIG.
22, it is advantageous because the abutting area can be increased (therefore, the magnetic path resistance is also reduced).

FIG. 2B shows a state in which a thin piece of permalloy or ferrite is inserted into the cut groove 18 shown in FIG. 2A through an insulating layer 19. etc. can be used.

Inserting the thin piece 21 of high magnetic permeability made of Nippermalloy or ferrite into the cut groove 18 in this manner is advantageous because it can compensate for the reduction in cross-sectional area due to the formation of the cut groove 818.

In order to clarify the effects of the magnetic head core based on this idea, the following table compares the playback characteristics and recording characteristics of the magnetic head based on this idea 2, measured using JIS (Japanese Industrial Standards) test methods, with those of the conventional product. This is what is shown.

In this table, all the specimens are made of Sendust alloy with the above-mentioned composition, have a thickness of approximately 0.6M, and a width (Y in Figure 1) of approximately 10 mm.
This magnetic head for cassettes (Philips type) is made up of two core members arranged as shown in FIG.

Conventional product ■← Each core member force of ma--sodo;
The conventional product (■) is made of a single piece of grooveless core material with a thickness of approximately 0.3 mm, and the invented product (■) is made of each core member. (Fig. 1 X)
Core material 1 with a thickness of approximately 0.6M with a cut groove portion of approximately 9m
A ferrite thin piece is inserted into the cut groove as shown in FIG. 2B, and the device (2) has the same structure as the device (2) except that the inserted thin piece is a permalloy thin piece.

According to the above table, it is clear that invented products I and II have playback and recording characteristics that are equal to or better than conventional product (1) (laminated type).

As a method for forming the cut groove portion 18 as shown in FIG. 2A, inexpensive mechanical processing using a wire saw, tungsten blade, cutting wheel, etc. can be used. The method using a two-stage wire saw will be explained with reference to FIG. 3c.

First, as shown in FIG. 3a, a block-shaped core material 30 made of sendust alloy is prepared, and a third
A profile polishing process is performed to form a recess 32 as shown in Figure b.

After this, as shown in the mBc diagram, no wires S1 to S8 are connected to Sl, S3. The set of S5, S7 and S2゜S4
Cut grooves 818 perpendicular to the recesses 32 in the material 30 using a wire saw that moves in the direction of the arrow while maintaining the height position in two steps, including the group S6.88.
is formed from the surface opposite to the recess formation surface, and at the same time, the material 3
0 into individual core members 12.

Such a method is advantageous in practice because relatively high-precision processing can be performed with only a few steps.

Note that the formation of the cut groove portion 18 and the core member 12 of the material 30
Of course, dividing into scales is a separate process.

In the embodiment described above, the smaller the width d of the cut groove portion 180 is, the larger the cross-sectional area of the magnetic circuit becomes, which is desirable.

Moreover, the effect of reducing eddy current is greater when the number of cut grooves 18 is two than one, and when the depth X of the cut grooves 18 is larger.

Further, the cut groove portion 18 does not necessarily have to have a uniform width extending from the rear end to the tip, and may have a non-uniform width.

In order to increase the mechanical strength, the cut grooves 18 can be partially interrupted.

As described above, according to this invention, by forming a cut groove in the butt core member and inserting a thin piece of permalloy or ferrite into the cut groove through an insulating layer, eddy current loss can be reduced and stable Excellent effects such as being able to obtain good frequency characteristics and simplifying the manufacturing process to reduce costs can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a top view showing a magnetic head according to an embodiment of this invention, and FIGS.
Fig. 7 is a sectional view taken along the line ■-n of one core member constituting the 7th board, in which figure A shows the state in which the cut groove is formed, and figure B shows the state in which a thin piece etc. is inserted into the cut groove. Figure 3a~
Figure 3 shows the process of forming the cut groove.
Figures a and 3b are perspective views, and figure 3c is a sectional view. 10... Magnetic head, 12, 22...
Core member, 14a, 16a...butting planned portion,
14, 24... Core tip, 16, 26...
... Core rear end, 18 ... Cut groove, 19
...Insulating layer, 21. ... thin section.

Claims (1)

[Claims for Utility Model Registration] (a) A core member for abutment made of a plate-shaped metal magnetic material having a pair of main surfaces facing each other, each of which has a thickness between its two end portions. (b) a thin piece made of permalloy or ferrite inserted into the cut grooves; (c) a thin piece of permalloy or ferrite inserted into the cut grooves; A magnetic head core having an insulating layer interposed between the inner surface of the cut groove and the thin piece.