JPH0770022B2 - Magnetic head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head, and more particularly, to a core base whose side surface facing the magnetic gap is inclined with respect to the magnetic gap surface, and a core base of the core base. The present invention relates to a magnetic head provided with a core half having a magnetic gap and a magnetic thin film made of a magnetic material having a high saturation magnetic flux density, which is deposited on the side surface facing the magnetic gap.

[Conventional technology]

The coercive force of the magnetic recording medium is increased with the increase in density of magnetic recording, and a magnetic head capable of recording on this magnetic recording medium is composed of a magnetic material having a high saturation magnetic flux density at least at a portion facing the magnetic gap. Development of magnetic heads is in progress.

As a result of various studies on the magnetic head of this type, the present inventors have previously found that the side surface of the core base facing the magnetic gap is inclined with respect to the magnetic gap surface, and the side facing the magnetic gap of the core base. Has proposed a magnetic head using a core half having a magnetic thin film made of a magnetic material having a high saturation magnetic flux density and attached to the side surface (Japanese Patent Laid-Open No. 58-15551).
See No. 3).

7 and 8 are partial plan views and partial cross-sectional views of the proposed magnetic head, and FIGS. 9 to 15 are explanatory views showing the manufacturing process of the magnetic head.

This magnetic head comprises a first core half 1 and a second core half 2
And an exciting coil 3 wound around the first core half body 1. The first core half body 1 and the second core half body 2 are made of ferrite or the like, and have a core base 5 having a chevron-shaped protrusion at approximately the center of the side surface facing the magnetic gap.
And a magnetic thin film 6 having a high saturation magnetic flux density deposited on the side surface of the core substrate 5. As shown in FIG. 7, the protrusion 4 and the magnetic thin film 6 on the first core half 1 side.
The shape of the protrusion 4 and the magnetic thin film 6 on the side of the second core half 2 is substantially symmetrical in the vicinity of the junction with the magnetic gap interposed therebetween.

Next, a rough manufacturing process of this magnetic head will be described. As shown in FIG. 9, a pair of grooves 8, 8 are provided in parallel on one surface of the ferrite block 7 constituting the core substrate 5, and a protrusion having a sharp tip (top) is provided between the grooves 8. Article 9 is formed. Next, a magnetic thin film 6 made of a magnetic material having a high saturation magnetic flux density and a high magnetic permeability is uniformly formed on the surface on which the grooves 8 and the ridges 9 are formed by a thin film manufacturing technique such as vapor deposition or sputtering (10th embodiment). See figure).

Then, as shown in FIG. 11, a reinforcing layer 8 made of a non-magnetic material such as gatatus is provided on the magnetic thin film 6 with a relatively large thickness, and then polished to the position shown by the alternate long and short dash line in FIG. This state is shown in FIGS. 12 and 13, in which a part of the magnetic thin film 6 on the tip of the ridge 9 is flatly polished to form a flat portion.
11 is formed.

In some of the blocks thus formed, coil grooves 12 are formed by cutting to a predetermined depth in a direction orthogonal to the ridges 9 as shown in FIG. Next, the block with the coil groove 12 and the block without the coil groove 12 (see FIG. 13) are integrally bonded by glass bonding so that the reinforcing layers 10 face each other as shown in FIG. To do. Then, the magnetic head is assembled by slicing along the alternate long and short dash line shown in FIG.

This conventionally proposed magnetic head mainly considers a magnetic head having a narrow track width of about 10 μm, such as a VTR. In order to manufacture a magnetic head having such a narrow track width, the apex angle θ1 of the protrusion 4 of the core substrate 5 shown in FIG. 7 is designed to be a relatively small angle of about 45 ° to 90 °. When the apex angle θ1 of the protrusion 4 is made acute in this way, when the sharp end of the magnetic thin film 6 is polished, the width of the flat portion 11 (see FIG. 12) corresponding to the track width even if the polishing allowance varies a little. It is possible to obtain a magnetic head in which the dimensional variation is kept small and the track width is always narrow.

[Problems to be solved by the invention]

However, when this magnetic head is applied to a wide one having a track width of about 40 to 200 μm, such as a recording / reproducing device for a magnetic disk, there are the following problems.

That is, in order to widen the track width, it is necessary to widen the width of the flat portion 11 of the magnetic thin film 6 corresponding thereto,
For that purpose, the magnetic thin film 6 must be attached thickly.
By the way, as described above, the apex angle θ of the protrusion 4 of the core substrate 5 is
When 1 is an acute angle, it takes too much time to apply the magnetic thin film 6 thickly, which results in poor productivity and high cost. On the other hand, if the magnetic thin film 6 is left thin, a desired recording track width cannot be obtained.

Further, in the case of the proposed magnetic head, since the magnetic thin film 6 is deposited on the ferrite block 7 and then the coil groove 12 is formed thereon, as shown in FIG.
The magnetic thin film 6 at the portion provided with is excluded from the core substrate 5. Therefore, the exciting magnetic flux generated by energizing the exciting coil 3 is always guided to the magnetic thin film 6 after passing through the core substrate 5 (made of ferrite), so that the magnetic permeability of the core half is poor. Furthermore, coil grooves are formed by machining such as cutting.
When forming 12, the magnetic thin film 6 may peel off from the core substrate 5 due to an external cutting force, resulting in poor yield and poor productivity.

In the proposed magnetic head, as shown in FIG. 7, the film thickness T of the magnetic thin film 6 is restricted to 1/2 or less of the width of the flat end portion of the magnetic thin film 6 corresponding to the track width. By doing so, the thickness T of the magnetic thin film 6 is substantially extremely thin (if the track width is 10 μm, the thickness T of the magnetic thin film 6 is 5 μm).
m or less), and therefore, the magnetic gap portion (near the flat end portion) is magnetically saturated, and therefore the portion of the magnetic thin film 6 apart from the magnetic gap portion is magnetically saturated, resulting in a high saturation magnetic flux. The advantage of using the magnetic thin film 6 having a density is not fully exhibited.

Furthermore, for example, when the track width is set to 10 μm for VTR, the film thickness of the magnetic thin film 6 is regulated to 5 μm or less. If the magnetic thin film 6 is extremely thin as described above, a uniform film should be formed. However, when the magnetic thin film 6 having a defect such as a pinhole is formed, it causes the above-mentioned magnetic saturation.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a magnetic head having excellent magnetic characteristics.

[Means for solving problems]

In order to achieve this object, the present invention is directed to a magnetic head in which a first core half body and a second core half body are joined via a magnetic gap.

The first core half has a first core base having a protrusion and a coil groove on both side surfaces facing the magnetic gap, the protrusion having both side surfaces inclined with respect to the magnetic gap surface, and the first core base. A first magnetic material having a high magnetic permeability and a high saturation magnetic flux density, which is continuously deposited along both side surfaces of the protrusion and the end opposite to the magnetic gap from the coil groove.
A magnetic thin film, and the interlocking angle θ2 on both sides of the protrusion exceeds 90 °.
The cross-sectional area of a portion, which is regulated in the range of 0 ° and is cut along one side of the magnetic gap from the one end of the protruding portion of the first core substrate perpendicularly to an imaginary line A, is S ₁ , The cross-sectional area of a portion cut along the virtual line B drawn from the other end of the magnetic gap perpendicularly to the other inclined side surface of the protruding portion of the first core base body is S ₂ , one end of the virtual line A and the virtual line B Virtual line C that connects one end of
S _{3 is} the cross-sectional area of the portion cut along the line, and S is the cross-sectional area of the magnetic thin film cut along the imaginary line D that is cut parallel to the magnetic gap surface from the position of the imaginary line C. _G , the saturation magnetic flux density of the first core substrate is B _S1 , and the saturation magnetic flux density of the first magnetic thin film is B _S2 , the first core substrate and the first magnetic thin film are configured so that the following relational expressions are established. , (S ₁ + S ₂ + S ₃ ) B _S2 + S ₄ · B _S1 ≧ S _G · B _S2 The second core half body is the second core base body and the magnetic gap surface of the second core base body. A second magnetic thin film made of a magnetic material having a high saturation magnetic flux density, which is continuously applied along the opposite side surfaces, and is formed by an exciting coil wound around a coil groove of the first core base. By pressing the middle part of the magnetic thin film and joining the first core half and the second core half together, It is characterized in that the end of the second magnetic thin film on the magnetic gap side and the end on the side opposite to the magnetic gap are pressed against each other.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings. First
1 is a plan view of the composite magnetic head according to the first embodiment, and FIG. 2 is a sectional view taken along the line ii in FIG.

This composite magnetic head is used for a magnetic disk recording / reproducing apparatus, and has a recording / reproducing head 21, an erasing head 22,
It is mainly composed of a non-magnetic body 23 for preventing a magnetic influence between both magnetic heads. These integrated components are attached to a head holder (not shown) such that the recording / reproducing head 21 is arranged on the upstream side in the traveling direction of the magnetic recording medium (magnetic disk) and the erasing head 22 is arranged on the downstream side.

The recording / reproducing head 21 includes a first core half 24, a second core half 25 facing the first core half 24, and a coil groove provided in the first core half 24.
It is mainly composed of an exciting coil 27 wound around 26. 28 is a reinforcing layer made of non-magnetic material such as glass.
It is provided near the joint between the core half 24 and the second core half 25.

The first core half body 24 is composed of a first core base body 30 having a chevron-shaped protrusion 29 substantially in the center of the side surface facing the magnetic gap 35, and a first magnetic thin film 31 deposited on the entire side surface. Has been done.

For the first core substrate 30, a ferrite having a high magnetic permeability such as manganese-zinc ferrite or nickel-zinc ferrite is used.

For the first magnetic thin film 31, a crystalline alloy or an amorphous alloy having a high saturation magnetic flux density and a high magnetic permeability is used. This crystalline alloy is an iron-aluminum-silicon alloy,
Examples include iron-silicon alloys and iron-nickel alloys. As the amorphous alloy, an alloy composed of 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, or Based on this, alloys containing elements such as aluminum, germanium, beryllium, tin, molybdenum, indium, tungsten, titanium, manganese, chromium, zirconium, hafnium, and niobium, or cobalt and zirconium as the main components, There are alloys containing additional elements.

Similarly to the first core half body 24, the second core half body 25 also has a second core base body 33 made of high magnetic permeability ferrite having a mountain-shaped protrusion 32 in the center of the side surface facing the magnetic gap 35, and And a second magnetic thin film 34 made of a metal magnetic material having a high saturation magnetic flux density and a high magnetic permeability, which is attached to the side surface of the.

As shown in FIG. 1, the protrusion 29 and the first magnetic thin film 31 on the side of the first core half 24 and the protrusion 32 and the second magnetic thin film 34 on the side of the second core half 25 are close to each other. The shape is almost bilaterally symmetric via the magnetic gap 35. The magnetic gap 35 has a length of about 100 to 140 μm.

On the other hand, the erasing head 22 mainly includes a first core half body 36, a second core half body 37 facing the first core half body 36, and an exciting coil 39 wound around a coil groove 38 provided in the second core half body 37. It is configured. 40 is a reinforcing layer made of non-magnetic material such as glass.
It is provided near the joint between the core half body 36 and the second core half body 37.

The first core half body 36 is composed of a first core base body 43 made of ferrite having high magnetic permeability and having two mountain-shaped protrusions 42 at predetermined intervals on the side surface facing the magnetic gap 41, and on the side surface thereof. The first magnetic thin film 44 is made of a metallic magnetic material having a high saturation magnetic flux density and a high magnetic permeability.

Similarly to the first core half body 36, the second core half body 37 is also a second core made of a high magnetic permeability ferrite having two chevron-shaped protrusions 42 on a side surface facing the magnetic gap 41 at a predetermined interval. Substrate 46 and second magnetic thin film made of a metallic magnetic material having a high saturation magnetic flux density and a high magnetic permeability, which is attached to the side surface of the substrate 46.
It consists of 47 and. Therefore, as shown in FIG.
The first core half 36 side projection 42 and the first magnetic thin film 44.
And the protruding portion 45 on the second core half 37 side and the second magnetic thin film.
The shape in the vicinity of the junction with 47 is substantially symmetrical with the magnetic gap 35 in between.

The magnetic gap 35 of the recording / reproducing head 21 and the erasing head 22
The two magnetic gaps 41 have a positional relationship as shown in FIG. 1, and a recording track is formed on the magnetic recording medium by the recording / reproducing head 21, and immediately after that, both ends of the recording track are partially formed by the erasing head 22. It is erased and the track width is regulated.

As shown in FIG. 1, the angle at which both inclined side surfaces of the protrusion 29 of the first core substrate 30 intersect, that is, the apex angle θ2 is 90 °.
It is regulated in the range of over 150 °. This apex angle θ
When 2 is 90 ° or less, that is, an acute angle, when the magnetic thin film 31 is deposited on the inclined surfaces on both sides of the protrusion 29 by vapor deposition or sputtering, the inclination of both sides of the protrusion 29 with respect to the raw material target forming the magnetic thin film 31 is increased. The angle of inclination of the surface is too large. Therefore, it takes too much time to form the thick magnetic thin film 31, and the productivity is poor. Further, when the apex angle θ2 is an acute angle, when the protrusion 29 is formed by cutting, a chip is likely to occur at the tip end thereof, resulting in poor yield.

On the other hand, when the apex angle θ2 becomes larger than 150 °, the protrusion 29
The vicinity of the tip end of the magnetic disk approaches a planar shape, and the vicinity of the tip end constitutes a pseudo magnetic gap, which is not preferable in terms of characteristics. Therefore, the tip portion of the protrusion 29 is not chipped, and the magnetic thin film 31 having a predetermined thickness is formed with good productivity.
In order to prevent the pseudo gap from being formed in the vicinity of the tip end of the, the apex angle θ2 of the protrusion 29 must be restricted to a range of more than about 90 ° and up to 150 °.

The regulation of the apex angle of the protrusion is not limited to the first core half 24 of the recording / reproducing head 21, but also the second core half 25 of the recording / reproducing head 21 and the first core half 36 and the second core half of the erasing head 22. The same applies to 37.

As shown in FIG. 2, the first core half 24 of the recording / reproducing head 21.
In addition, the coil grooves 26 and 38 are formed in the second core half 37 of the erasing head 22, respectively, but the order is different from that of the previously proposed magnetic head. That is, before applying the magnetic thin films 31, 47 to the core bases 30, 46, the magnetic thin films 31, 4
The coil grooves 26, 38 are formed in consideration of the film thickness of 7, and then the magnetic thin films 31, 47 are deposited. Therefore, as shown in the figure, the magnetic thin films 31 and 47 are formed continuously from the upper part to the lower part without being divided by the coil grooves 26 and 38 in the middle.

Further, by winding the exciting coils 27, 39 in the coil grooves 26, 38, there are magnetic thin films 31, 47 having high magnetic permeability just below the exciting coils 27, 39, and therefore, the exciting coils 27, 39 are provided.
The electromagnetic conversion characteristics between the core and the core are good.

Further, by integrally joining the first core halves 24,36 and the second core halves 25,37, the magnetic gap side end portions of the first magnetic thin films 31,44 and the second magnetic thin films 34,47 and The opposite ends are pressed against each other. From such a thing,
The first magnetic thin films 31 and 44 can be mechanically adhered to the first core bases 30 and 43 side, and the second magnetic thin films 34 and 47 can be mechanically adhered to the second core bases 33 and 46 side, respectively. An increase in magnetic resistance can be suppressed.

FIG. 3 is a plan view of the vicinity of the magnetic gap 35 in the recording / reproducing head 21, and FIG. 4 is a cross-sectional view taken along the line of FIG.

In the magnetic path other than the magnetic gap facing surface of the first core half 24, a product of a cross-sectional area substantially perpendicular to the direction of the magnetic flux flowing in the first core base 30 and the saturation magnetic flux density of the first core base 30, As a result of examining the place where the sum of the cross-sectional area almost perpendicular to the direction of the magnetic flux flowing in the first magnetic thin film 31 and the product of the saturation magnetic flux density of the first magnetic thin film 31 becomes the smallest, FIG. 3 and FIG. It was clarified that it is the position of A, B, C, D, E shown by the virtual line in the figure.

That is, an imaginary line A drawn from one end of the magnetic gap 35 perpendicularly to one inclined side surface of the projecting portion 29 of the first core base 30, and from the other end of the magnetic gap 35 to the other inclined side surface of the projecting portion 29. A virtual line B drawn perpendicularly to the magnetic head, a virtual line C connecting one end of the virtual line A and one end of the virtual line B, a virtual line D lowered from the position of the virtual line C parallel to the magnetic head surface, and the virtual line It is a position indicated by an imaginary line E vertically lowered from one end of D toward the first magnetic thin film 31 on the inclined surface 48 side.

The inventors of the present invention have variously studied the thickness of the magnetic thin film 31 on which the characteristics of the magnetic thin film 31 deposited on the surface of the first core substrate 30 can be sufficiently exhibited, and as a result, the following relational expression is satisfied. It has been found that, with this structure, the effect of using the magnetic thin film 31 having a high saturation magnetic flux density can be sufficiently exhibited.

That is, the cross-sectional area of the portion cut along the imaginary line A shown in FIGS. 3 and 4 is S ₁ , the cross-sectional area of the portion cut along the imaginary line B is S ₂ , and the cross-sectional area cut along the imaginary line E. The cross-sectional area of the portion is S ₃ , the cross-sectional area of the portion cut along the virtual line C and the virtual line D is S ₄ , and the magnetic gap facing area of the magnetic thin film 31 is
S _G , the saturation magnetic flux density of the first core substrate 30 is B _S1 , the magnetic thin film 31
If the defined saturation magnetic flux density and _{B S2, (S 1 + S} 2 + S 3) B S2 + S 4 · B S1 ≧ S and such that _{G · B S2 ...... (1)} , the first core base 30 and first magnetic thin film 31
Make up.

Thus, the product of the cross-sectional area almost perpendicular to the direction of the magnetic flux flowing in each part of the magnetic thin film 31 and the saturation magnetic flux density of the magnetic thin film 31 [(S ₁ + S ₂ + S ₃ ) B _S2 ] and the core substrate Even at the position where the sum of the cross-sectional area almost perpendicular to the direction of the magnetic flux flowing in 30 and the product of the saturation magnetic flux density [S ₄ · B _S1 ] of the core substrate 30 is the smallest, the total value is the magnetic thin film. The product of the area facing the magnetic gap of 31 and the saturation magnetic flux density of the magnetic thin film 31 [S _G
B _S2 ] If the core substrate 30 and the magnetic thin film 31 are configured as described above, the portion of the magnetic thin film far from the magnetic gap is magnetically formed before the vicinity of the magnetic gap as conventionally proposed. The effect of using the magnetic thin film 31 having a high saturation magnetic flux density can be sufficiently exhibited without being saturated, and excellent magnetic characteristics can be obtained.

The product of the cross-sectional area and the saturation magnetic flux density means the maximum amount of magnetic flux that can pass through the magnetic flux without magnetic saturation in the cross-section.

In the case of the magnetic head of this embodiment, the portions other than the magnetic gap portion of the magnetic path forming the magnetic circuit of the core half are the cross-sectional areas S ₁ , S ₂ , S ₃ , and S ₄ . Therefore, the total amount of magnetic flux in those portions, that is, the total amount of magnetic flux in the portion other than the magnetic gap portion of the magnetic path of the core half becomes the sum of the products of the cross-sectional area and the saturation magnetic flux density.

Furthermore, the minimum value of the total sum is equal to or greater than the product of the area of the magnetic gap and the saturation magnetic flux density means that the total amount of magnetic flux in the portion of the magnetic path forming the magnetic circuit of the core half body other than the magnetic gap is , Which means that it is larger than the amount of magnetic flux on the magnetic gap surface. In other words, it means that the portion other than the magnetic gap portion is not magnetically saturated before the magnetic gap portion.

5 and 6 are diagrams for explaining the second embodiment. This embodiment is suitable for increasing the length of the magnetic gap 35, in other words, the recording track width.
Two or more protrusions 29 and two protrusions 32 of the second core base 33 are arranged side by side, and the first magnetic thin film 31 and the second magnetic thin film 34 are deposited thereon.

Also in this embodiment, in the magnetic path other than the magnetic gap facing surface of the first core half 24, the cross-sectional area substantially perpendicular to the direction of the magnetic flux flowing in the first core base 30 and the first core half 30 thereof. The sum of the product of the saturation magnetic flux density, the cross-sectional area substantially perpendicular to the direction of the magnetic flux flowing in the first magnetic thin film 31 and the product of the saturation magnetic flux density of the first magnetic thin film 31 is the smallest The positions are shown by imaginary lines A, B, C and D in the drawings and FIG.

The cross-sectional area of the part cut along the imaginary line A shown in the figure
S ₁ , the cross-sectional area of the portion cut along the imaginary line B is S ₂ , the cross-sectional area of the portion cut along the imaginary line E is S ₃ , and the cross-sectional area of the protrusion 29 cut along the imaginary line C is S ₅ , S ₇ , the cross-sectional area of the magnetic thin film 31 cut along the imaginary line C is S ₆ , the magnetic gap facing area of the magnetic thin film 31 is S _G , and the saturation magnetic flux density of the core substrate 30 is
If the saturation magnetic flux density of B _S1 and the magnetic thin film 31 is defined as B _S2 , (S ₁ + S ₂ + S ₃ + S ₆ ) B _S2 + (S ₅ + S ₇ ) B _S1 ≧ S _G · B _S2 … …
(2) so that the first core substrate 30 and the first magnetic thin film 31
Make up.

In order to manufacture a magnetic head that satisfies the above condition (1) or (2), the apex angle θ2 of the protrusion on the core substrate is restricted to a range of more than 90 ° to 150 ° as described above. It can be easily created.

In the above embodiment, the case where the magnetic thin film is formed on the core substrate made of a magnetic material such as manganese-zinc ferrite has been described. However, the core substrate is made of a non-magnetic material such as non-magnetic ferrite or ceramic, and the surface thereof is magnetic. The present invention is also applicable to a magnetic head that forms a thin film, and in this case, B _S1 in the expressions (1) and (2) is zero.

Further, although the first core half of the recording / reproducing head has been described in the above embodiment, it is needless to say that the present invention can be applied to other core half.

〔The invention's effect〕

 The present invention has the following operational effects.

． According to the present invention, a first core base having a protrusion having side surfaces inclined to the magnetic gap surface on the side facing the magnetic gap, both side surfaces of the protrusion of the first core base, and the magnetic gap. In a core half having a structure including a first magnetic thin film deposited along the end opposite to the first core substrate, a cross-sectional area perpendicular to the direction of the magnetic flux flowing in the first core substrate and saturation of the first core substrate. The product of the magnetic flux density, the cross-sectional area perpendicular to the direction of the magnetic flux flowing in the first magnetic thin film, and the first
It was specified that the sum of the product of the saturation magnetic flux density of the magnetic thin film and the virtual lines A, B, C, D, and E was the smallest.

Then, when the magnetic head is manufactured, the thicknesses of the core substrate and the magnetic thin film at the positions of the virtual lines A to E are monitored so that the relational expressions as described above are established. A part of the magnetic thin film away from the magnetic gap will not be magnetically saturated, and the magnetic head that can fully exert the effect of using the magnetic thin film having a high saturation magnetic flux density can be stably mass-produced. It is possible and consistent in quality.

． A magnetic thin film made of a magnetic material having a high saturation magnetic flux density on the surface of the core base using a core base having a protrusion and a coil groove whose side surface facing the magnetic gap is inclined with respect to the magnetic gap surface. In the magnetic head formed by depositing the same, there are a narrow track type and a wide track type.

In other words, in a narrow track with a track width of about 20 μm, in other words, the magnetic thin films formed on both side surfaces of the protrusion are extremely thin, and the flat surface of the joint between both magnetic thin films is as narrow as 20 μm. It is possible to magnetically saturate the vicinity of the magnetic gap before the other parts of the magnetic thin film only by forming the magnetic thin films on both side surfaces of the magnetic thin film.

On the other hand, in the case of a wide track having a track width of 40 to 200 μm, if the magnetic thin films on both sides of the protrusion are not made thick enough by forming the magnetic thin films on both sides of the protruding portion, the magnetic thin film near the magnetic gap will be formed. The magnetic head cannot be magnetically saturated before the other parts, so that the life of the magnetic head is short.

Further, in order to make the magnetic thin film considerably thick, it takes a long time to form the film by, for example, sputtering or vapor deposition, resulting in poor productivity.

In this wide track type, if a magnetic thin film is continuously formed from the coil groove to the end on the side opposite to the magnetic gap part in addition to the both side surfaces of the protruding part as in the present invention, the vicinity of the magnetic gap can be sufficiently formed. It is possible to saturate, and it is not necessary to increase the thickness of each magnetic thin film so much, which improves productivity.

． The linear expansion coefficient is different between the core substrate and the magnetic thin film, so that when the temperature is changed, the magnetic thin film is likely to be peeled off from the core substrate, and the magnetic resistance at the contact surface between the two tends to increase.

In that respect, according to the present invention, by integrally joining the first core half body and the second core half body, the magnetic gap side end portions of the first magnetic thin film and the second magnetic thin film and the end portion on the opposite side thereof are formed. The structure is such that they are pressed against each other. Therefore, the magnetic thin film and the core substrate can be brought into close contact with each other, and the increase in the magnetic resistance between them due to the temperature change can be suppressed.

． Since the intermediate portion of the magnetic thin film having a high magnetic permeability exists just below the exciting coil, the electromagnetic conversion efficiency between the exciting coil and the core is good.

[Brief description of drawings]

FIG. 1 is a plan view of a composite magnetic head according to the first embodiment, FIG. 2 is a cross-sectional view taken along the line EE of FIG. 1, and FIG. 3 is a plan view of a magnetic read / write head of the composite magnetic head in the vicinity of a magnetic gap. Explanatory drawing, FIG. 4 is a cross-sectional explanatory view on the line of FIG.
FIG. 5 is an explanatory plan view in the vicinity of the magnetic gap of the magnetic head according to the second embodiment, FIG. 6 is an explanatory sectional view taken along the line of FIG. 5, and FIG. 7 and FIG. Partial plan view and partial cross-sectional view of the head, and FIGS. 9 to 15 are explanatory views showing the manufacturing process of the magnetic head. 21 …… Recording / playback head, 22 …… Erasing head, 24,36 ……
First core half, 25,37 …… Second core half, 26 …… Coil groove, 27 …… Excitation coil, 28,40 …… Reinforcing layer, 29,32,42…
… Projection part, 30,43 …… First core substrate, 31,44 …… First magnetic thin film, 33,46 …… Second core substrate, 34,47 …… Second magnetic thin film, 35,41 …… Magnetic Gap, 48 …… Lower inclined surface, θ2
...... An interlinking angle of both side surfaces of the protrusion, A imaginary line drawn perpendicularly from one end of the magnetic gap to one inclined side surface of the protrusion, B ...... An imaginary line drawn perpendicular to the other inclined side surface, C ... an imaginary line connecting one end of the imaginary line A and one end of the imaginary line B, and D ... parallel to the magnetic head surface from the position of the imaginary line C. Virtual line lowered, E ... Virtual line vertically lowered from one end of the virtual line D toward the first magnetic thin film on the inclined surface side.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hideo Fujiwara 1-88, Tora, Ibaraki-shi, Osaka Within Hitachi Maxell Co., Ltd. (72) Minoru Yamano 1-88, Tora-tora, Ibaraki-shi, Osaka Hitachi Maxel Co., Ltd. (72) Inventor Takeshi Tottori 1-88, Tora, Ibaraki-shi, Osaka Hitachi Maxell Co., Ltd. (72) Noboru Kumasaka, Inventor 1-280, Higashi Koigakubo, Kokubunji, Tokyo Hitachi, Ltd. Central Research Laboratory (72) Inventor Shigekazu Otomo 1-280 Higashi Koigakubo, Kokubunji, Tokyo Hitachi Central Research Laboratory (72) Inventor Norihiro Kudo 1-280 Higashi Koigakubo, Kokubunji, Tokyo Hitachi Central Research Institute (72) Inventor Juichi Morikawa 1410 Inada, Katsuta City, Ibaraki Prefecture Hitachi Ltd. Tokai Plant (56) References JP-A-56-169214 (JP, A) JP-A-58-155513 (JP, A) JP-A-58-220232 (JP, A) JP-A-59-207415 (JP, A)

Claims (1)

[Claims] 1. A magnetic head formed by joining a first core half body (24) and a second core half body (25) through a magnetic gap (35), wherein the first core half body (24) comprises: A first core base (30) having a protrusion (29) having side surfaces inclined to the magnetic gap surface and a coil groove (26) on the side surface facing the magnetic gap (35), and the first core thereof. High permeability and high saturation magnetic flux density continuously applied from both sides of the protrusion (29) of the base body (30) and along the end opposite to the magnetic gap (35) from the coil groove (26). First made of a magnetic material having
A magnetic thin film (31), the interlocking angle θ2 of both side surfaces of the protrusion (29) is restricted to a range from more than 90 ° to 150 °, and the first core extends from one end of the magnetic gap (35). Base (30)
S _{1 is} a cross-sectional area of a portion cut along an imaginary line A drawn perpendicularly to one inclined side surface of the projecting portion (29) in S, and the first core base body (30) from the other end of the magnetic gap (35). S ₂ , the imaginary line A is the cross-sectional area of the portion cut along the imaginary line B drawn perpendicularly to the other inclined side surface of the protrusion (29) in FIG.
S _{3 is} a cross-sectional area of a portion cut along an imaginary line C connecting one end of the phantom line and one end of the phantom line B, and is cut along an imaginary line D lowered from the position of the imaginary line C in parallel with the magnetic gap surface. The cross-sectional area of the portion is S ₄ , and the first magnetic thin film (31) is formed on the lower inclined surface (48) of the protrusion (29) from one end of the virtual line D.
S _{5 is} a cross-sectional area of a portion cut along an imaginary line E that is vertically lowered toward, a magnetic gap facing area of the first magnetic thin film (31) is S _G , and a saturation magnetic flux density of the first core substrate (30) is To B _S1 ,
When the saturation magnetic flux density of the first magnetic thin film (31) is B _S2 ,
The first core substrate (30) and the first magnetic thin film (31) are configured so that the following relational expressions hold, and (S ₁ + S ₂ + S ₃ ) B _S2 + S ₄ · B _S1 ≧ S _G · B _S2 The second core half body (25) is continuously deposited along the second core base body (33) and the side surface of the second core base body (33) opposite to the magnetic gap surface. And a second magnetic thin film (34) made of a magnetic material having a high saturation magnetic flux density, and by joining the first core half body (24) and the second core half body (25) together, A magnetic head characterized in that the thin film (31) and the second magnetic thin film (34) are pressed against each other at the magnetic gap side end and the magnetic gap side end and the opposite end.