JPH0766492B2 - Magnetic head - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a recording / reproducing magnetic head, and more particularly to a VTR magnetic head using metal magnetism.

[Background of the Invention]

Conventionally, a magnetic head using a metal magnetic material has been used as a magnetic material forming a magnetic head core. The magnetic head using a metal magnetic material has a high saturation magnetic flux density of the material, is capable of sufficiently recording even on a metal tape having a high coercive force, and has excellent characteristics of low sliding noise.

However, since the magnetic metal has a low specific resistance and a large eddy current loss, the effective magnetic permeability in the video frequency region is lower than that of the conventional high-permeability ferrite material with the commonly used head-shaped core thickness. There is a drawback that

Recently, in order to solve the above problem, a magnetic head has been proposed in which a metal magnetic material having a thickness of a track width and a protective material having excellent wear resistance are combined (Japanese Patent Laid-Open No. 56-1241).
12, No. 57-138119).

In this type of magnetic head, as shown in FIG. 1, protective materials 11, 11 'are provided on both side surfaces of a metal magnetic body 10 constituting a magnetic circuit. Here, in the figure, 12 is an operating gear via a non-magnetic material, and 13 is a coil winding window. In addition, such a magnetic head core is made into a composite block by the process shown in FIG. In FIG. 2 (a), a metal magnetic body 10 having a thickness equal to the track width is formed on the protective material 11 by vapor deposition or sputtering, and the other protective material 11 'is joined at the surface of the metal magnetic body 10. Thus, a composite block 14 as shown in FIG. 2 (b) is obtained. The composite material at this time is resin glass,
There are raw materials.

On the other hand, the protective material has wear resistance against the metal magnetic material of the core material,
Coefficient of thermal expansion. It is selected from materials with low electrical conductivity such as glass and ceramics whose workability is set appropriately.

However, when these protective materials are bonded together with a magnetic metal material and a resin, glass, or brazing material is used, there are advantages and disadvantages to the bonding of dissimilar materials, and they are not sufficiently satisfactory. For example, resin can be bonded relatively easily, but it has the greatest drawback that it is not reliable in accuracy and humidity and that the resin exudes on the surface during tape running. On the other hand, glass has strong bonding strength with the protective material, but weak bonding strength with the metal magnetic material. The reverse is true for brazing materials. As described above, even if they are bonded via the intermediate film, the bonding strength is weak, and a problem such as peeling during processing occurs, and the processing yield is low.

On the other hand, the track width for recording and reproducing signals has become narrower with the progress of higher density magnetic recording.
The track width of the R magnetic head is about 30 μm, which is extremely small. In the magnetic head having such a small track width, when the head core thickness T _W is equal to the track width t _W , the magnetic resistance of the head core increases, and as shown in FIG. The cutouts 15 and 15 'are provided near the gear to reduce the thickness of the head core to a track width t _W, and for other parts, the head core thickness T _W is set to be larger than the track width t _W. It is common practice to reduce the resistance and increase the read sensitivity of the magnetic head. Further, this increases the area of the tape sliding surface of the magnetic head, and is therefore effective in improving wear resistance.

Track such a magnetic head obtained by subtracting the track width than the thickness of Hetsudokoa (hereinafter referred to as narrow Toratsukuhetsudo) in the case of producing a metal magnetic body, for example by machining a composite block 14, as Figure 4 Width restriction groove 16,1
6'is provided to process the track width to a predetermined size. However, in this case, there is a problem that the dimensional accuracy of the track width of the completed magnetic head is deteriorated or a great amount of time is spent to maintain the dimensional accuracy, resulting in lack of mass productivity.

[Object of the invention] The object of the present invention is to eliminate the above-mentioned conventional drawbacks, in a magnetic head in which a metal magnetic material and a protective material are combined, the bonding strength is high, the processing yield is excellent, and the wear resistance is a narrow track. It is to provide the structure of the magnetic head.

[Outline of Invention]

According to the present invention, in a magnetic head in which a main magnetic path forming surface of a metal magnetic body having a shape of a magnetic head is sandwiched by two protective substrates, at least one of the protective substrate surfaces forms a continuous pair.
A plurality of shallow grooves are provided, and a metal magnetic body having a thickness substantially equal to or larger than the track width of the magnetic head is embedded in the pair of grooves so that the track width is smaller than the core thickness. It is a magnetic head configured in.

A specific example is shown in FIG. That is, protective material
A pair of continuous shallow grooves is formed on at least one surface of 11 and 11 ', and the shallow magnetic grooves are filled with the metal magnetic material 10. The track width is obtained by reducing the thickness of the core. The main trace of the protective materials 11 and 11 'is performed at the joint surfaces 17, 17' of the protective materials. The joined composite block is divided into magnetic core halves 18 and 18 ', and coil winding groove 13 is formed in at least one of the core halves, and then the core halves are abutted on the operating gear tap abutment surface via a non-magnetic gear tap material. Body 18 , 1
Obtain a magnetic Hetsudokoa by joining 8 '. The main joining at this time is similarly performed on the surface of the protective material, and in addition, a part of the coil winding window or the rear portion of the core may be filled with the joining reinforcing material. FIG. 5 (b) shows the structure of the tape sliding surface. The both ends of the shallow groove are provided with an inclination so that the edge of the metal magnetic material filled in the shallow groove and the operating gear do not have a parallel portion.

Example of Invention

Hereinafter, the features of the magnetic head structure and the method for manufacturing the same will be described in detail with reference to examples.

FIG. 6 shows a first embodiment of the process for producing the magnetic head of the present invention. (A) and the like indicating the order of steps correspond to (a) and the like in FIG. 6, respectively.

(A) A protective substrate 20 forming one side surface of the magnetic head is prepared. The protective substrate is made of a non-magnetic ceramic material, the width a is about 3 mm in core width, and the length b is about 2.5 mm in core height.
(The length of the two pieces is shown), the thickness c is half the core thickness, which is about 1 mm, and includes the machining allowance. The upper surface 21 becomes a bonding surface with the other protective substrate (described later).
Two shallow grooves 22 and 22 'which are continuous with the joining surface 21 are formed so that the ends thereof adjacent to each other overlap, and a shallow groove 23 for filling the metal magnetic material is provided. At this time, both ends of the shallow grooves 22 and 22 'are provided with an inclination so as to give an azimuth loss so that the edge of the metal magnetic material filled in the shallow groove and the operating gear have no parallel portion. The end does not work as a pseudo gear. The angle θ of the inclined part is 30
The range was from ° to 60 °. The shallow groove 23 is formed so as to be slightly deeper than the track width of the magnetic head in the central projection (the portion where the shallow grooves 22 and 22 'overlap) and deeper in other areas, and the groove width is made narrower than the core width. , Process so as to leave the bonding surface with the protective material. The processing is performed by a grindstone or mask etching.

(B) Next, a film 24 made of a metal magnetic material such as sendust or various amorphous magnetic material alloys is formed in the shallow groove 23 by a thin film forming technique such as vapor deposition or sputtering.

(C) Next, the excess metal magnetic material generated in the above-mentioned magnetic film 24 forming step is removed by grinding, polishing, etc. to form a joint surface. At this time, the thickness of the metal magnetic film 24 at the central protruding portion is made substantially equal to the track width t _W of the magnetic head, and the protective substrate surface appears on both end surfaces.

(D) Next, the glass 25 is provided on the polished surface (bonding surface) by means such as spattering.

(E) Next, the other protective substrate 20 'is overlaid.
It is desirable that the bonding surface of the protective substrate 20 'be mirror-polished, and in some cases, if a glass film is also formed on the polishing surface, the bonding strength can be improved.

(F) Next, the above-mentioned protective substrates 20 and 20 'that have been overlapped are heated while being pressurized to form a bonded body 26 .

(G) Next, the joined body 26 is divided at the center to form a set of core block halves 27, 27 '. After that, the butt surfaces 28, 28 'of the gears to be butt-joined again are mirror-polished.

(H) Next, a groove 29 for coil winding is formed on at least one gear butting surface. Thereafter, a non-magnetic gear film is formed on the gear butting surfaces 28, 28 'by a sputtering method to a specified thickness. In this case, a high melting point glass may be formed at the front butting portion of the magnetic head core, and a low melting point glass serving as a bonding material may be formed at the rear butting portion.

(B) Next, the two co-block halves 27, 27 'are butted against each other and heated and joined while being pressed to form the magnetic head core block 30. At this time, as a reinforcing material, the joining strength can be increased by replenishing a part of the coil winding window with glass. The strength of the main joints is ensured by the joints 31, 31 'of the protective material. That is, since the oxide-based protective material has a good leak property with respect to glass and excellent bonding strength, problems such as peeling hardly occur in the processing step. (Nu) Next, a single magnetic head core 32 as shown in (nu) is obtained by cutting along the dotted line.

(L) Next, as shown in (L), the core width T (about 150μ
Cutting to m) gives the magnetic head 33 according to the invention.

Another embodiment of the present invention is shown in FIGS. 7 (a) to (d) and FIGS. 8 and 9.

In step (a), the protective substrate 20 is provided with a shallow groove 23 for filling with a metal magnetic material. At this time, a flat portion that is shallower than the other portions and is parallel to the protective substrate surface is provided in the central portion of the shallow groove 23. The depth of the shallow groove in the flat part is slightly deeper than the track width of the magnetic head.

In the step (b), the metal magnetic material 24 is vapor-deposited or sputtered to the extent that the shallow groove is filled.

In the step (c), the unnecessary portion of the metal magnetic film is ground,
It was removed by polishing, and the thickness of the metal magnetic film in the central flat portion was defined to be the track width t _{W of the} magnetic head.

The subsequent steps are manufactured by the steps shown in FIGS. 6 (d) to 6 (l), and a magnetic head core having the structure of the tape sliding surface as shown in step (d) is obtained.

According to the present invention, since the portion defining the track width t _W of the magnetic head can be widened, the dimensional accuracy of the obtained magnetic head is high.

On the other hand, in the case of manufacturing a magnetic head core having a wide track width, it can be obtained by stacking two blocks filled with a metal magnetic film as shown in FIG. 8 or 9.

The metal magnetic film to be filled may be a single-layer film or a multi-layer film with an insulating film sandwiched in the middle. In particular, in a magnetic head core having a wide track width, the use of a multilayer film can reduce the eddy current loss, so that the high frequency characteristics do not deteriorate.

Further, according to the present invention, as shown in FIG. 10, the flow of the magnetic flux in the magnetic circuit made of a metal magnetic material is restricted near the actuating gear 12, so that the magnetic head has high recording and reproducing sensitivity. It is particularly effective when a multilayer film is used.

〔The invention's effect〕

According to the present invention, in a magnetic head in which a side surface of a metal magnetic body having the shape of a magnetic head is sandwiched by two protective substrates,
Two continuous shallow grooves forming a set on at least one of the protective substrates are integrally provided so that adjacent ends overlap with each other, and a metal magnetic body having a thickness substantially equal to the track width is embedded in the grooves to integrate them. Since the thickness of the metal magnetic material in the central portion of the groove is equal to the track width, the groove for regulating the track width is not required, and the narrow track magnetic head with high dimensional accuracy can be easily obtained.

In addition, since the main bonding strength is a structure composed of two bonded joints on the surfaces of the protective substrates, the use of a non-magnetic, high hardness material of an acid-based material for the protective substrate allows The bonding strength with the glass is increased, the problem of peeling in the heading process is almost eliminated, and the heading yield is significantly improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a structure of a conventional magnetic head, FIGS. 2 (a) and 2 (b) are block perspective views showing a method of manufacturing a conventional magnetic head, and FIG. 3 is an explanatory view of a narrow track head. Four
FIG. 5 is a process diagram showing a method for producing a narrow track head from a conventional composite block, FIG. 5 is a perspective view of a core showing an example of the magnetic head of the present invention, and FIGS. FIG. 7 is a perspective view and a plan view for explaining the head manufacturing process, FIGS. 7 (a) to (d), FIG. 8 and FIG. 9 are magnetic head manufacturing process diagrams and heads for explaining another embodiment of the present invention. FIG. 10 is a plan view of the tip, and FIG. 10 is an enlarged view of the head core for explaining the flow of magnetic flux. 10, 24 ... Metal magnetic material, 11, 20 ... Protective material, 22, 23 ... Metal magnetic material filling groove, 25 ... Bonding material.

Claims (2)

[Claims] 1. A magnetic head in which two core halves are joined together via a magnetic gear, wherein the core half is formed by filling a groove provided in a protective substrate with a metal magnetic material, and A magnetic head, characterized in that a side edge portion opposite to the gear cup is inclined with respect to the magnetic gear cup, and a track width is smaller than a thickness of the head core. 2. A flat portion which is shallower than the other portion of the groove and is parallel to the surface of the protective substrate is formed in the vicinity of the central portion of the groove, and the operating portion is formed by the flat portion. The magnetic head according to claim 1.