JPS6371906A - Magnetic head - Google Patents

Abstract

PURPOSE:To improve yield at the time of manufacture by making the boundary between a magnetic block and a magnetic film include an extended section extending from near the end of a magnetic gap to outer periphery and a lined section lined with the magnetic gap, and forming the extended section on a straight line that intersects the magnetic gap, and making the lined section not existing on the straight line. CONSTITUTION:The unit is divided into two areas, i.e. an area F1 that extends from an end of a gap 7 to outer periphery and oblique to the gap 7 and an area F2 lined with the gap 7 and parallel to the gap 7. The boundary S1 (extended section) between the area F1 and the ferrite 1 is inclined to the gap 7 by theta=45 deg., and the boundary S2 (lined section) between the area F2 and ferrite is parallel to the gap 7. As the boundary S2 between the area F2 and ferrite is parallel, larger contour effect appears with the length of the parallel part, and the peak to peak value of ripple formed on the frequency-output characteristic curve becomes larger. When such ripple is less than about 2dB, no bad influence is exerted on reproduced video pictures.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a magnetic head, and in particular, a magnetic block made of a first magnetic material has a higher saturation magnetic flux density than the first magnetic material and a magnetic permeability. The present invention relates to a magnetic head in which core halves each coated with a magnetic film made of a second magnetic material having a low magnetic flux butt against each other through a magnetic gap disposed between the magnetic films.

<Conventional technology> In order to perform good magnetic recording and reproducing on magnetic recording media with higher coercive force than before, a magnetic metal film with high saturation magnetic flux density is coated on an oxide magnetic material block with high magnetic permeability. A composite magnetic head is made by abutting two core halves together through a magnetic gap, the so-called M
l I n G a p ) heads have been proposed and implemented.

There are two types of ki I G heads: one type in which the boundary between the alloy magnetic film and the oxide magnetic block on the sliding surface of the W body is parallel to the gap (this will be referred to as the P type), and the other type in which the boundary is parallel to the working gap. Non-parallel type with unmasked (
This will be called type A. For example, JP-A-54
It is disclosed in Japanese Patent Laid-open No. 60-30107, etc. ). However, in the P type, a phenomenon called the contour effect occurs due to the discontinuity of magnetic properties at the boundary between the high magnetic permeability material and the alloy magnetic material parallel to the gap, and ripples appear as noise in the frequency vs. output characteristic curve. However, it has not been put to practical use as a recording/reproducing head.

Therefore, up to now, A type MIG heads have been put into practical use for video tape recorders (VTRs).

FIG. 9 shows a schematic structure of a conventional MIG head for a VTR in a perspective view.

In FIG. 9, 11+12 is single crystal ferrite as a high magnetic permeability material, 2□, 2□ are sendust alloy films as high saturation magnetic flux density materials, and the thickness of the alloy film 2 is approximately 2
It is 0 μm. Reference numeral 7 indicates an operating gap with a thickness of about 0.23 μm formed of a non-magnetic material such as 5i02, 10 a wire-wound window, and 6 and 9 low melting point glass.

Ferrite 1 on the recording medium sliding surface of the head in FIG.
The boundary between the film 2 and the sendust film 2 forms an angle of about 45° with the gap 7, so there is no contour effect and the output is high (and exhibits excellent electromagnetic conversion characteristics).

In addition, both ends of the operating gap 7 are supported by highly wear-resistant ferrite material, which results in less uneven wear (it is clear that the head has good running stability and is structurally superior).

[Problem that the invention seeks to solve]

However, it is made of materials with different coefficients of linear expansion from ferrite, sendust, and glass, and when the glass is butted and welded, the temperature must be raised to around 600°C and then cooled down to room temperature again. If the thickness is too large, internal stress will accumulate at the joints and interfaces of each material, and as a result of the process of releasing it, the ferrite or glass may crack or, in severe cases, break. There is a lot of room for stabilizing the process from a yield standpoint.

Furthermore, the head having the structure shown in FIG. 1 is not suitable for use in a recording system with a wide track width, for example, when the track width is as much as 60 μm. Because Sendust film 2
If the thickness of the film is T, then the working gap length is f2·T since the film 2 is inclined at 45 degrees with respect to the gap.If you want to obtain a head with a desired track width of 60 μm and an azimuth angle of 0 degrees, , the film thickness is 'F2ζ60μm/f2ζ42μ
It reaches up to m. Attempting to obtain such a film thickness would not only take a long time to form the film, but also cause the ferrite substrate, which is the substrate, to crack due to the internal stress of the film itself, and even if the film could be formed without any problems, it would The problems in the welding process as described in detail become even more serious, and the yield rate up to the head chip becomes extremely low.

The present invention was made in view of the above-mentioned problems, and an object of the present invention is to provide a structure of a magnetic head that has good magnetic recording and reproducing characteristics, improves manufacturing yield, and can form a magnetic head that has a wide track width. shall be.

<Means for Solving the Problems> With this object in mind, in the present invention, a magnetic block made of a first magnetic material is provided with a material having a higher saturation magnetic flux density and a lower magnetic permeability than the first magnetic material. A magnetic head in which core halves each coated with a magnetic film made of a second magnetic material having low magnetic properties are brought into contact with each other through a magnetic gap disposed between the magnetic films, and the magnetic head on the medium sliding surface is The boundary between the block and the magnetic film includes an extending portion extending from near the end of the magnetic gap to the outer edge, and a parallel portion parallel to the magnetic gap, and the extending portion intersects with the magnetic gap. The parallel portions are formed on a straight line, and the parallel portions do not lie on the straight line.

<Operation> By configuring as described above, good magnetic recording and reproducing characteristics can be obtained by the magnetic film in contact with the above-mentioned extended portion, and since the track width is determined by the length of the parallel portion, the film thickness can be increased. Since the track width can be widened without any problems, it has become possible to improve the yield during manufacturing.

<Example> Examples of the magnetic head of the present invention will be described below.

FIG. 1 is a perspective view schematically showing a magnetic head as an embodiment of the present invention.

In Fig. 1, 1 (1, 1 □) is a high magnetic permeability material (first magnetic material) such as single crystal ferrite, and 2 (2, 2 □) is a high magnetic permeability material (first magnetic material) such as sputtering, etc. An alloy magnetic material (second magnetic material) having a high saturation magnetic flux density such as permalloy, sendust, amorphous, etc. formed by physical vapor deposition.
, 7 is a working magnetic gap formed of a non-magnetic material such as 5iO8 with a thickness of 0.2 μm to 0.3 μm depending on the design,
4 is a wire-wound window groove; 6 is a first low-melting glass; 9 is a low-melting glass having a melting point similar to or lower than that of the glass 6; 10
is a wire-wound window.

The structural features of this head will be explained with reference to FIG. 2, which shows the shape of each part appearing on the medium sliding surface.

The features of the cross-sectional shape of the sendust film 2 appearing on the sliding surface in FIG.
A region F2 parallel to and parallel to the gap 7 (
This is a point that can be divided into two areas (shaded area). In this example, the boundary SI between the oblique region F and the ferrite l
(extended part) is inclined at θ=45° with respect to gap 7,
A boundary S2 (parallel portion) between the region F2 and the ferrite 1 is parallel to the gap 7. ]・Rack width WT is 3
It is set to 0 μm. At this time, in the head with the structure as shown in FIG. 9, the film thickness T 2 =Wrsimθ=30 μm/'r2
= 21 μm, the film thickness T1 of this head is 1
It can be made as thin as 4 μm.

The shape of region F2 has a thickness of 10 in the direction perpendicular to the gap.
The length of the side parallel to the 8m1 gap is 20 μm. Since the boundary -52 of region F2 with the ferrite is parallel, the longer the parallel part, the greater the contour effect appears.
The peak-to-peak value of the ripple that occurs on the frequency-output characteristic curve becomes thicker.

If such ripple is about 2 dB or less, it will not cause any bad shadow on the video reproduced image.

An advantage of the structural features of this head lies in the simplicity of the mounting process. Parts 3 to 6 show the main manufacturing processes with these advantages.
This will be explained using figures.

In FIG. 3, 1 is a part of a rectangular parallelepiped block of ferrite single crystal, and the - face thereof has a large number of parallel first grooves 3. with a V-shaped cross section. ~34 is engraved. Each groove 3. ~3
The angle θ between the slope S, ~S4 of No. 4 and the groove forming surface is 10°.
Above, 40° to 60° is desirable. Next, cut the groove 4 for the winding window, and attach the sendust 2 to a thickness of 14 μm on the slopes S1 to S4.
A film is formed to a thickness of about m.

FIG. 4 shows a state in which a first grade metal rod 5 is dropped into the groove 4 after film formation. In Fig. 4, ferrite block 1
The film thickness T3 of the sendust film formed on a surface other than the slope of the groove, for example, the surface facing the gap, was several tenths larger than the film thickness of the slope, and in the case of θ-45°, it was about 20% larger, about 18 μm. .

The manufacturing advantage of this head is that since the thickness of the metal film formed on the slope can be made thinner, the head can be manufactured even if sendust is formed in the groove for the winding window. If a film of 20 μm thick is formed on the slope as in the conventional method, a film of 25 μm thick will also be deposited on the surface of the 6M section 4 for the winding window facing the cap.
During the subsequent glass welding process, thermal stress caused cracks in the ferrite parts around the grooves, reducing yield. Therefore,
In order to prevent the sendust film from forming on the winding window groove 4, the first groove 31 is formed in the ferrite block l in FIG.
After cutting ~34, Sendust was formed, and then grooves for winding windows were cut. In this process, the grindstone used to cut the grooves for the winding windows was subject to considerable wear and tear as it cut through different materials, sendust and ferrite.

In the case of this head, after cutting the first grooves 31 to 34 in Fig. 3, the winding window groove 1 shown by the dotted line can be processed immediately, and only the ferrite material needs to be processed, so the grinding wheel has a long life. It is also effective. That is, one advantage is that the sendust film can be formed after forming the winding window groove 4 on the ferrite.

FIG. 5 shows that in FIG. 4, the aluminum rods 5 and the first grooves 3 to 34 to which the sendust film is adhered are connected to the first low melting point glass 6.
The figure shows the state halfway through carving a second groove of 83.8 degrees for track width processing after embedding and surface lapping to form a butting surface.

Assuming that the thickness of the remaining film wrapped to form the abutting surface in Fig. 5 is 74, when creating the head shown in Fig. 9, it is necessary to wrap at least until T4=O. For the head, 18μm is T4=10μm
It was only necessary to wrap up to 100 degrees, and the wrapping time was also significantly shortened. That is, another advantage is that the butt surface lapping time can be shortened.

FIG. 6 shows the second grooves 81, 8□, . . . in FIG. 5.
After processing all of..., SiO2 is applied to the butting surfaces.
After attaching about 0.2 μm of non-magnetic material such as, etc., a block similar to that shown in FIG. 84 is used to show a state in which the second glass 9 having a melting point similar to or lower than that of the first glass is welded.

The aluminum rod was cut at the cut plane position indicated by the dotted line perpendicular to the butting surface and buried in the groove for the winding window, and dissolved in alkaline solution.
After forming the winding window and processing the necessary sliding surfaces, the head chip shown in FIG. 1 is completed. If you want to add azimuth to the head, just tilt the cut surface as much as necessary with respect to the gap surface.

As is clear from the manufacturing process described above, generally speaking, MIG heads are heads made by processing three materials with different physical and chemical properties into a complex shape and joining them: metal, ferrite, and glass. , during the manufacturing process from room temperature to 6.
It is obtained through a harsh manufacturing method that requires a glass welding process in which the temperature is raised to around 000C and then returned to room temperature, and then machining processes such as grooving and cutting.As a result, ferrite and Cracks form in the glass, significantly reducing yield. Such a phenomenon naturally occurs when the deposited metal magnetic film has a thick culm. Therefore, in the case of this head, as explained in FIG. 2, the thickness of the deposited alloy magnetic film can be made thinner. The thinner it is, the better the yield will be.

In other words, another advantage in manufacturing this head is that the thickness of the alloy magnetic film can be reduced, reducing the time required for the film formation process, and another advantage is that the phenomenon of cracking in ferrite and glass can be suppressed. The goal is to improve overall yield.

Due to the advantages described above, the manufacturing process is simplified, time is shortened, and yield is improved, making it possible to reduce costs with this head.

Another embodiment in which the head of the present invention is suitably used is shown in FIG. The structural differences between the head shown in Fig. 7 and the head shown in Fig. 1 are that the track width in the head shown in Fig. 7 is approximately twice as large as 60 μm, and an alloy magnetic film is formed on the wall surface 4 of the winding window groove. There are two points: a point where no bonding is applied.

In order to achieve a track width of 60 μm with the type of head shown in Figure 1, a 40 μm thick alloy magnetic film was required on the side surface of the core diagonal to the gap (region Fl in Figure 2). In the case of 2071m, the remaining part of the track width is the area parallel to the gap (area
), it is easy to obtain a head with a good yield and a wide track width.

In addition, when the alloy magnetic film in the oblique region F1 is 25 μm or more, it is better to avoid cracks in the ferrite if the alloy magnetic film is not adhered to the wall surface of the winding window groove, as in the head shown in FIG. It is smaller (higher yield).

However, in terms of electromagnetic conversion characteristics, if the alloy magnetic film is coated on the wall surface of the groove for the winding window, especially on the surface that intersects diagonally with the gap, the output will be slightly higher and the contour will be slightly higher when compared at the same gap depth. - There are few effects.

Next, we will discuss still another embodiment of the present invention, particularly a case where the alloy magnetic film on the head sliding surface has various shapes, as shown in FIG.
Shown in a) to (f).

The shapes of the alloy magnetic films shown in FIGS. 8(a) to (e) are as follows.
In the region F2 parallel to the gap in the figure, it can be said that the boundary line S2 between the alloy magnetic film and the ferrite is changed from being parallel to the gap to various non-parallel boundary lines. Such deformation of the boundary line complicates the manufacturing process, but it is possible to further suppress the occurrence of contour effects.

Note that the alloy magnetic film 2. in the heads of FIGS. 2 and 8(a) to (e). and 2□ are point symmetrical with respect to the gap center, but they may also be line symmetrical with respect to gap 7,
Furthermore, the shapes of the alloy magnetic films on the left and right core halves may be different. In the head shown in Figure 8(f), a core half-hole having the shape shown in Figure 9 is used for the core half-hole without the winding window, and a core half-hole similar to that in Figure 1 is used for the core half-hole having the winding window. It is something. This is because the ferrite block without the winding window groove has less processing distortion, so even if the alloy magnetic film on the side surface of the core tip is made thicker, the manufacturing yield is relatively high.

Further, the winding window groove can be provided not only on one half of the core but also on both.

<Effects of the Invention> As explained above, according to the magnetic head of the present invention, it is possible to achieve good magnetic recording and reproducing characteristics and improve yield during manufacturing, and it is also possible to manufacture a magnetic head with a wide track width. can.

[Brief explanation of the drawing]

1 is a perspective view schematically showing the structure of a magnetic head as an embodiment of the present invention; FIG. 2 is a plan view schematically showing the structure on the sliding surface of the head of FIG. 1; 6 are perspective views for explaining the main steps of the manufacturing method of the head shown in FIG. 2, and FIG. 7 is a perspective view schematically showing the structure of a magnetic head as another embodiment of the present invention. Figures 8(a) to 8([) are plan views showing various configurations on the head sliding surface of embodiments of the present invention, respectively, and Figure 9 is a plan view of the MIG head currently in practical use. FIG. 2 is a perspective view schematically showing the structure. ■++ '2 is a high magnetic permeability material block (first magnetic material block) such as ferrite single crystal that constitutes the main part of the core, 21,2□ is a high permeability material block such as alloy magnetic material coated on the tip of the core. a film made of a saturated magnetic flux density material (a film made of a second magnetic material),
3 (31 to 34) are first grooves carved in the high magnetic permeability material block 1, 4 is a groove for a winding window, 5 is a metal rod, and 6 is a winding in which the first groove and the metal rod 5 are installed. A first low-melting point glass fills the groove 4 for the line window, 7 is an actuating cap formed of a thin non-magnetic film, and 8 (8,, 8°...) defines the track width. The second groove 9 is a second low-melting glass that fills the second groove 8 in the butt welding process, lO is the volume i', ! ν window, SI, S2 is the boundary between the high magnetic permeability material block and the high saturation magnetic flux density material film, and S is the extension part, S2
is the parallel part. Appeasement mouth is crawling fiercely

Claims (2)

[Claims] (1) A core half formed by covering a magnetic block made of a first magnetic material with a magnetic film made of a second magnetic material having a higher saturation magnetic flux density and lower magnetic permeability than the first magnetic material. A magnetic head is formed by abutting two magnetic blocks through a magnetic gap arranged between the magnetic films, and the boundary between the magnetic block and the magnetic film on the medium sliding surface is located near the end of the magnetic gap. and a parallel part parallel to the magnetic gap, the extended part is formed on a straight line intersecting the magnetic gap, and the parallel part does not lie on the straight line. A magnetic head characterized by: (2) Claim (1) characterized in that at least a part of the parallel portion is parallel to the magnetic gap.
The magnetic head described in Section 1.