JPH0561681B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a magnetic head, and in particular to a core base portion whose side surface facing a magnetic gap is inclined with respect to the magnetic gap surface, and this core base portion. The present invention relates to a magnetic head having a core half comprising a magnetic thin film made of a magnetic material having a high saturation magnetic flux density and coated on the side surface facing the magnetic gap.

[Background of the invention]

With the increasing density of magnetic recording, the coercive force of magnetic recording media has been increased, and as a magnetic head capable of recording on this magnetic recording medium, at least the portion facing the magnetic gap is made of a magnetic material having a high saturation magnetic flux density. Development of magnetic heads is progressing.

As a result of various studies on this type of magnetic head, the present inventors first discovered a core base portion whose side surface facing the magnetic gap is inclined with respect to the magnetic gap surface, and a magnetic gap of the core base portion. proposed a magnetic head using a core half with a magnetic thin film made of a magnetic material having a high saturation magnetic flux density and coated on the opposing side surface (Japanese Patent Application Laid-Open No. 1983-1999).
(See No. 155513).

13 and 14 are a partial plan view and a partial sectional view of the proposed magnetic head, and FIGS. 15 to 21 are explanatory diagrams showing the manufacturing process of this magnetic head.

This magnetic head is mainly composed of a first core half 1, a second core half 2, and an excitation coil 3 wound around the first core half 1. The first core half 1 and the second core half 2 include a core base 5 made of ferrite or the like and having a chevron-shaped protrusion 4 at approximately the center of the side facing the magnetic gap, and a core base 5 that is covered with the side surface of the core base 5. It is composed of a magnetic thin film 6 having a high saturation magnetic flux density. As shown in FIG. 7, the protrusion 4 and magnetic thin film 6 on the first core half 1 side and the protrusion 4 and magnetic thin film 6 on the second core half 2 side have shapes near the joint that form a magnetic gap. It is almost symmetrical between the two sides.

Next, an outline of the manufacturing process of this magnetic head will be explained. As shown in FIG. 15, a pair of parallel grooves 8, 8 are provided close to each other on one side of the ferrite block 7 constituting the core base 5, and a protrusion having a pointed tip (top) is provided between the grooves 8. Section 9 is formed. Next, a thin film manufacturing technique such as vapor deposition or sputtering is applied to the surface on which the grooves 8 and protrusions 9 are formed to create a magnetic material made of a magnetic material with high saturation magnetic flux density and high permeability, as shown in FIG. The thin film 6 is formed uniformly.

Next, a relatively thick reinforcing layer 8 made of a non-magnetic material such as glass is provided on the magnetic thin film 6 as shown in FIG. 17, and then polished to the position shown by the solid chain line in the same figure. FIGS. 18 and 19 show this state, in which a part of the magnetic thin film 6 on the tip of the protrusion 9 is polished flat to form a flat portion 11.

Some of the blocks formed in this way are
As shown in FIG. 20, a coil groove 12 is formed by cutting to a predetermined depth in a direction perpendicular to the protrusion 9. Next, a block with this coil groove 12 formed therein and a block with no coil groove 12 formed therein (first
The blocks shown in FIG. 9) are bonded together by glass bonding so that the reinforcing layers 10 face each other as shown in FIG. Then, by cutting along the dashed-dotted line in the same figure,
Assemble the magnetic head.

This conventionally proposed magnetic head was designed as a magnetic head for a VTR with a track width of about 20 to 30 μm. In order to manufacture a magnetic head having such a large track width, the magnetic thin film 6 is formed uniformly in the longitudinal direction of the grooves 8 and the protrusions 9, as shown in FIG. Therefore, as shown in FIGS. 18 and 19, a flat portion 11 is formed by polishing the magnetic thin film 6 on the tip of the protrusion 9 flat.
is constant in the longitudinal direction with a width corresponding to the track width tw. One block thus formed is joined together so that the track widths tw of the magnetic films are opposed to each other, as shown in FIG. Such positioning of the track width portion is performed on the side facing the recording medium.

However, the track width of this magnetic head is
When applied to a narrow track magnetic head of 10 μm or less, there are the following problems.

FIGS. 22 to 24 are diagrams showing an example thereof. The head core shown in these figures is a magnetic head core sliced from the block shown in FIG. FIG. 22 is a plan view seen from the side facing the recording medium, FIG. 23 is a plan view seen from the opposite side, and FIG. 24 is A-A in FIGS. 22 and 23.
It is a sectional view on a line. The block shown in FIG. 24 is made by combining the two blocks shown in FIGS. 19 and 20 into one piece by butting together the flat parts 11 of the magnetic thin film 6 that have been polished so that the part thereof is equal to the track width tw. It is joined. Positioning at this time is performed on the surface facing the recording medium shown in FIG. Therefore, accurate positioning can be achieved on the side facing the recording medium. However, on the other side, when a dimensional deviation occurs during block processing or a positional deviation occurs during butting work, it is necessary to butt the flat portions 11 of the magnetic thin film 6 on the entire surface as shown in FIG. 24. There are some things that I can't do. In that case, positional deviation occurs on the opposite side, so that the bonding area on the opposite side decreases as shown by the shaded area. As a result, the joint viewed from the opposite side of the core is
As shown in FIG. 23, the flat portion 11 of the magnetic thin film 6
are shifted from each other. When such a problem occurs, the magnetic resistance of the magnetic path constituting the magnetic head increases, resulting in a significant deterioration of recording and reproducing characteristics. Furthermore, even if the recording/reproducing characteristics are obtained, the dispersion of the characteristics becomes large.
Combination work is also difficult when used in combination with a plurality of heads. In conventional magnetic heads with wide track widths, even slight deviations did not affect the head characteristics much.
If the magnetic head has a narrow track of 20 to 30 μm or less, characteristics will deteriorate. When such a phenomenon occurs, variations in the inductance of the magnetic head core increase. In particular, when we disassembled a magnetic head with low inductance, we found that the bonding area of the magnetic thin film at the rear became narrower.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the drawbacks of the prior art described above and to provide a narrow-touch magnetic head having excellent magnetic properties.

[Summary of the invention]

To achieve this object, the present invention provides a magnetic head comprising two core halves joined via a magnetic gap, the core halves having a side surface facing the magnetic gap facing the magnetic gap surface. A core base having a protruding portion with both side surfaces inclined at an angle, and a magnetic thin film made of a magnetic material having a high saturation magnetic flux density coated on the side of the core base facing the magnetic gap. , when the magnetic thin film adhered to at least one core half is thicker on the rear bonding surface side than on the side facing the magnetic gap, and a flat portion is formed in the magnetic thin film of the protrusion provided on the core base, The width of the flat portion is wider on the rear joint surface side than on the side facing the magnetic gap.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a plan view of a magnetic head according to a first embodiment of the present invention. Figures 2 and 3 are Figure 1B
FIG. 3 is a cross-sectional view taken along line -B (magnetic gap abutting surface).

In FIG. 1, the magnetic head 30 mainly includes a first core half 31, a second core half 32 opposite thereto, and an excitation coil 40 wound through a coil groove provided in the first core half 31. It is composed of. 37 is a reinforcing layer made of a non-magnetic material such as glass, which connects the first core half 31 and the second core half 3.
It is provided near the joint of 2. The first core half 31 has a first core base 3 having a chevron-shaped protrusion 38 approximately at the center of the side surface facing the magnetic gap 41.
3, and a first magnetic thin film 35 adhered to the side surface.

The first core base 33 is made of, for example, manganese.
A ferrite with high magnetic permeability, such as zinc ferrite or nickel-zinc ferrite, is used.
In some cases, a non-magnetic material may be used. In this case, the magnetic thin films 35 and 36 constitute a magnetic circuit. Note that when the core base is made of ferrite having high magnetic permeability, the magnetic path may be formed of a magnetic thin film, or may be formed of a magnetic thin film and high magnetic permeability ferrite.

On the other hand, for the first magnetic thin film 35, a crystalline alloy or an amorphous alloy having high saturation magnetic flux density and high magnetic permeability is used. Examples of such crystalline alloys include iron-aluminum-silicon alloys, iron-silicon alloys, and iron-nickel alloys. The amorphous alloy may include one or more elements selected from the group of iron, nickel, and cobalt, and one or more elements selected from the group of phosphorus, carbon, boron, and silicon.
Aluminum, germanium, beryllium, tin, mobdenum, indium, tungsten, titanium, manganese, chromium, zirconium,
Alloys with added elements such as hafnium and niobium,
Alternatively, there are alloys containing cobalt and zirconium as main components and the above-mentioned additive elements.
Furthermore, small amounts of noble metal elements such as gold, silver, platinum, and ruthenium may be added to adjust magnetostriction, crystallization temperature, etc.

Similarly to the first core half 31, the second core half 32 also includes a second core base 34 made of high magnetic permeability ferrite and having a chevron-shaped protrusion 39 approximately at the center of the side surface facing the magnetic gap 41; It is comprised of a second magnetic thin film 36 made of a metallic magnetic material having high saturation magnetic flux density and high magnetic permeability, which is adhered to the side surface of the magnet. As shown in FIG. 1, the protrusion 38 and the first magnetic thin film 35 on the first core half 31 side and the protrusion 39 and the second magnetic thin film 36 on the second core half 32 side are shaped in the vicinity of the joint. are substantially symmetrical across the magnetic gap 41. This magnetic gap portion 41 has a length corresponding to a track width of about 5 to 30 μm. Note that the magnetic gap is approximately 0.1 to 0.3 μm.

Note that the protruding portion of the core base shown in FIG. 1, that is, the apex angle θ is not particularly limited,
A range of 90 degrees is preferred. If the apex angle θ is less than 30 degrees, the mechanical strength of the protrusion will be weakened, and the protrusion will often be missing during processing, resulting in poor production yield. In addition, if the apex angle θ exceeds 90 degrees, the magnetic thin film 3
5 and 36, when polishing the tip of the magnetic thin film to form a flat part equal to the track width, even if the polishing amount varies slightly, the width dimension will vary widely, making it difficult to control the track width. There are some drawbacks such as: The present invention will be explained in detail below. Note that the same parts in the present invention are indicated by the same numbers and symbols.

FIGS. 2 and 3 are diagrams for explaining the main parts of the present invention.
It is a sectional view cut on the -B line. Figure 2 is the first
The magnetic gap facing surface in the core half 31, the third
The figure shows the surface of the second core half 32 facing the magnetic gap.

As shown in FIG. 2, in the flat part composed of the magnetic thin films 35, 35', the rear flat part 35' (lower part of the figure) is wider than the width tw of the flat part 35 (upper part of the figure) forming the magnetic gap. Make the width tw wide.

In this case, the width tw of the flat portion 35 of the magnetic thin film corresponds to the track width. In this example, the width tw is 10μm
The width Tw of the rear flat part 35' is 15 to 20 μm (tw
1.5 to 2 times).

In contrast, the second core half 3 shown in FIG.
The width tw' of the flat part 36 composed of the magnetic thin film No. 2 is
It was assumed to be equivalent to tw, and constant up to the rear.

FIG. 4 shows a third core on top of the first core half 31 in FIG.
FIG. 4 is a diagram showing the positional relationship between the magnetic thin films 35, 35' and 36 when the second core halves 32 shown in the figure are butted against each other.
That is, the dotted line portion in FIG. 4 corresponds to the magnetic thin film 3 in FIG.
6, which shows a state in which the magnetic thin films 35 and 35' of FIG. 2 are butted against each other with a misalignment. As is clear from FIG. 4, in the first core of FIG. 2, the lower magnetic thin film 3 is wider than the width tw of the upper magnetic thin film 35
By widening the width Tw of 5′, the third
Even if the magnetic thin film portion 36 of the second core half shown in the figure is butted against each other with misalignment, the joint area (shaded area)
has not changed. In this way, when the first core half 31 and the second core half 32 are butted against each other, the facing area of the magnetic thin film portions will always be constant. the result,
The inductance of the magnetic core can be kept constant, and variations in the recording and reproducing characteristics of the magnetic head can be reduced.

Note that the width Tw of the lower magnetic thin film 35' is 1.5 to 1.5 to the width tw of the upper magnetic thin film 35 of the first core half 31.
It is preferable to make it about twice as large. If Tw is less than 1.5 times, the machining accuracy and alignment accuracy of the core half blocks relative to each other will be severe, resulting in poor production yield. Furthermore, if Tw is twice or more than tw, the time for depositing the magnetic thin film will be twice or more, resulting in poor productivity.

Next, a second embodiment of the present invention will be described with reference to FIGS. 5 and 6. Figure 5 shows the first core half 3
1 and 6 show the second core half 32, and respectively show cross-sectional views taken along the line B--B of the magnetic core in FIG.

In FIG. 5, the width of the magnetic thin films 35, 35' is
It was set as tw and constant. On the other hand, the width tw' of the magnetic thin film 36 in _FIG .
It was made twice as wide as Tw. In this way, the same effect as the method described in the first embodiment can be obtained.

Note that the first core half tw and the second core half tw' may have the same width, and if the required track width is tw, alignment is facilitated by making tw' slightly wider. The permissible width varies depending on the device specifications, but it is sufficient to ensure that adjacent recorded signals or adjacent signals do not have an adverse effect on reproduction. For example, tw′ is the width that appears at both ends of tw by 2 to 3 μm.
It is preferable to keep it within.

Next, an embodiment of the method for manufacturing a magnetic head according to the present invention will be described with reference to FIGS. 7 to 12. As shown in FIG. 7, a pair of grooves 44, 4 are formed close to each other on one side of the ferrite block constituting the first core half 31.
4 are provided in parallel, and a protrusion 38 having a sharp tip (top) is formed between the grooves 44. Next, a magnetic thin film 35 made of a magnetic material with high saturation magnetic flux density and high magnetic permeability is uniformly coated on the surface on which the grooves 44 and protrusions 38 are formed using a thin film manufacturing technique such as vapor deposition or sputtering. . The thickness of the magnetic thin film 35 on the side surface of the protrusion was approximately 10 μm.

Further, the second core half 32 (not shown) is also subjected to the same process.

Next, as shown in FIG. 8, a first core half 31 having a coil winding groove 42 and another first core half 3 are separated.
1' are arranged close to each other, the surface on the side where the tip magnetic gap is formed is covered with a mask 43, and a magnetic thin film 35' of about 10 μm is again deposited on the rear abutting surface. Therefore, the thickness of the magnetic thin film is approximately twice as thick on the rear abutting surface than on the side where the tip magnetic gap is formed.

Next, as shown in FIG.
A relatively thick reinforcing layer 37 made of a non-magnetic material such as glass is provided on the layer 35', and then polished to the position shown by the solid chain line in the figure. As shown in FIG.
5 until a flat portion having a width tw (corresponding to the track width) is formed on the side where the tip magnetic gap is formed. In this example, tw was set to 10 μm. At this time, the width of the magnetic thin film on the rear abutting surface is approximately twice the width tw since it has been deposited twice as thick in advance (see Figure 2). This state is shown in the 11th
FIG. FIG. 11 is a perspective view of the first core half block, and FIG. 12 is a perspective view of the second core half block. After a non-magnetic thin film is deposited on the surfaces of the first core half block and the second core half block to obtain a predetermined magnetic gap, the magnetic thin film parts tw and tw' of each are arranged to face each other. and join them together. By cutting this, a plurality of magnetic heads as shown in FIG. 1 can be obtained.

The embodiment described above is just one example, and it goes without saying that the present invention can be applied to other modified magnetic heads in which a magnetic thin film is used as a magnetic circuit.

〔Effect of the invention〕

As explained above, the present invention has the above-mentioned structure, and provides a magnetic head that is easy to process and assemble even in a magnetic head with a narrow track width of 20 to 30 μm or less, and has little variation in recording and reproducing characteristics. can be obtained. Furthermore, the characteristics of the magnetic thin film having a high saturation magnetic flux density can be fully exhibited, and a magnetic head having excellent magnetic properties can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view of a magnetic head according to a first embodiment of the present invention, and FIGS. 2, 3, and 4 are cross-sections of a core half for explaining the first embodiment of the present invention. Figures 5 and 6 are sectional views of the core half taken along the line B-B in Figure 1 for explaining the second embodiment of the present invention, Figures 7, 8, 9 and 10. 11 and 12 are manufacturing process diagrams of a magnetic head according to the present invention, and FIGS. 13 and 14 are a partial plan view and a partial cross-sectional view, respectively, for explaining the structure of a conventionally proposed magnetic head. Figure, Figure 15, Figure 16
17, 18, 19, 20 and 21 are explanatory diagrams showing the manufacturing process of a conventional magnetic head. FIG. 3 is a partial plan view and a partial cross-sectional view of the head. 30... Magnetic head, 31... First core half, 32
...Second core half, 38, 39...Protrusion, 33...First core base, 34...Second core base, 35, 35',
36...Magnetic thin film, 41...Magnetic gap, 42...Coil winding groove.

Claims (1)

[Claims] 1. Two core halves are joined via a magnetic gap, and the core halves form a protruding portion with both side surfaces facing the magnetic gap inclined with respect to the magnetic gap surface. , comprising a magnetic thin film made of a magnetic material having a high saturation magnetic flux density and deposited on the side surface of the core substrate facing the magnetic gap, wherein the magnetic thin film deposited on at least one half of the core is When the rear bonding surface side is made thicker than the magnetic gap facing surface side and a flat portion is formed in the magnetic thin film of the protrusion provided on the core base, the width of the flat portion is thicker than the rear bonding surface side than the magnetic gap facing surface side. A magnetic head characterized by having a wide surface.