JPH0219522B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head suitable for use in combination with a high coercive force magnetic recording medium, and in particular, a magnetic head that can achieve high coercive force at a short recording wavelength by being constructed using a magnetic alloy thin film. effectively magnetizes the magnetic recording medium of
The frequency characteristics of the magnetic head are improved to enable broadband magnetic recording.

Regarding a magnetic head that uses this kind of magnetic alloy thin film and is suitable for use in combination with a magnetic recording medium of high coercive force, a patent application filed in 1973 by the applicant is filed.
Conventionally, including the one described in the specification of -90908,
The following two types of magnetic heads were considered.

In other words, (1) In order to prevent the tip of the magnetic head that is in contact with the high coercive force magnetic recording medium from being magnetically saturated, a large number of layers of magnetic alloys with a high saturation magnetic flux density B _S are laminated using a well-known thin film formation method. A magnetic alloy film multilayer magnetic head in which the entire head chip is composed of a magnetic alloy film.

(2) In order to prevent the tip of the magnetic head that is in contact with the high coercive force magnetic recording medium from becoming magnetically saturated, only the tip of the head chip, where magnetic saturation is a problem, is placed under a magnetic field with a large saturation magnetic flux density B _S. A magnetic alloy film ferrite composite magnetic head comprising an alloy film and the other part of the head chip comprising ferrite having a large effective magnetic permeability μ _e at high frequencies.

Although the magnetic alloy film multilayer magnetic head described in item 1 has good characteristics, it has to be manufactured one by one by a butting method, resulting in low productivity and poor product characteristics. The disadvantage was that there was a large variation in the

On the other hand, although the magnetic alloy film ferrite composite magnetic head described in item 2 has much better productivity than the former, it has been found that it has the following drawbacks in terms of characteristics.

That is, the results of actually measuring the characteristics of this kind of magnetic alloy film ferrite composite magnetic head described in the specification of Japanese Patent Application No. 54-90908 mentioned above show that the conventional composite magnetic head of this kind has the upper surface shown in FIGS. 1a and 1b. Since the joint surface S of the alloy film m and the ferrite F is parallel to the opposing surface of the head gap g, the effective magnetic permeability μ of the alloy film m and the ferrite F is If _e has different values, the head gap g
The distance between the two bonding surfaces S, S that sandwich the two, that is, the bonding distance G, etc., also acts equivalently as a head gap, and the originally desired head gap g formed between the magnetic alloy films m, m. It has been found that the magnetic head reproduces output e _h -frequency characteristic as shown in FIG. 2a, for example, as shown in FIG. 2a.

Therefore, the reproduction output-frequency characteristic shown in FIG. 2a is different from the reproduction output-frequency characteristic shown in FIG. It can be considered that the reproduced output-frequency characteristics as shown in FIG. 2c, which are exhibited by the originally desired head gap g due to m, are superimposed.

Therefore, to examine in detail the superposition of the desired and undesired head gap characteristics as described above, the recording frequency is MHz when the relative running speed between the magnetic recording medium and the magnetic head is vm/s. The wavelength λμm is expressed by the following equation (1).

λ=v/...(1) Also, the magnetic recording medium, which is magnetized in a sinusoidal manner with a period of recording wavelength _λ〓n , has a velocity relative to the reproducing head.
The reproduction output voltage e _h induced in the head coil when the vehicle is relatively traveling at vm/s is expressed by the following equation (2).

e _h = −8π ² Wδ _n nηI _r cos2πt × [sinπg/λ/πg/λ] (term of head gap loss) × [e ^- 〓 ^s/ 〓] (term of space loss between medium and head) × [1- e ² 〓〓 ^m/ 〓/2πδm/λ〓〓/2πδm/λ] (term of medium thickness loss)...(2) Where, W: recording track width δm: medium thickness n: number of head coil turns η: head reproduction efficiency _Ir : medium residual Magnetization g: Head gap length s: Space between medium and head According to equation (2), magnetic head reproduction output voltage e _h
As for the frequency characteristics, first, the reproduction output voltage e _h increases in proportion to the recording frequency, and then the reproduction output voltage e _h tends to decrease due to various losses. As a result, as shown in Fig. 2c It can be seen that the characteristics are as shown in .

Among the various losses, the loss of interest in the present invention relates to the head gap length g, so only the second term of the head gap loss in equation (2) will be considered in more detail.

That is, when a signal recorded on a magnetic recording medium at the recording wavelength λ expressed by equation (1) is reproduced by a magnetic head having a head gap of gap length G, the gap loss L _G is expressed by the second equation of equation (2).
According to the terms, it becomes as follows.

_L. = 20 μm, so from equations (1) and (3), the reproduced output voltage e _h drops at every frequency of about 4.5 MHz, producing a dip, resulting in the characteristics shown in FIG. 2b.

On the other hand, since the originally desired gap length g is 1 μm, the frequency at which the dip first occurs in the reproduced output-frequency characteristic curve shown in Figure 2b is
86 MHz, which is the frequency range of interest in the present invention, there is no effect of gap loss, and the reproduced output-frequency characteristic shown in FIG. 2c, which is determined by factors other than the head gap, can be obtained.

Next, the second problem discovered by the inventors while studying the performance of the magnetic alloy film ferrite composite magnetic head mentioned in Section 2 above is that the 4-head type
When the contact pressure between the magnetic head and the magnetic tape is large, such as in a VTR, in the conventional magnetic alloy film ferrite composite magnetic head having the structure shown in Fig. 1, the bond between the magnetic alloy film m and the ferrite F is Since the mutual adhesion force at the surface S is not sufficient and the bonding surface S extends perpendicularly to the running direction of the magnetic tape, a minute gap is created in the bonding surface S, making it difficult to use as a magnetic head. This means that the characteristics of the product will be significantly deteriorated. On the other hand, if the same conventional composite magnetic head is used in a magnetic sheet recording/reproducing device with a small contact pressure with the magnetic head, the relative running speed between the magnetic sheet and the magnetic head will be 2 times higher than that of the above-mentioned 4-head VTR. equivalent to twice
Even when raised above 80 m/s, no gap was observed at the joint surface S as described above.

The object of the present invention is to solve the various problems of the conventional art described above at once, eliminate the drawbacks thereof, and provide a magnetic alloy film that does not cause deterioration of characteristics due to the presence of a bonding surface between the magnetic alloy film and the ferrite. An object of the present invention is to provide a ferrite composite magnetic head.

That is, in the magnetic head of the present invention, among the magnetic cores constituting the magnetic path in the magnetic head, a core portion forming a magnetic gap at a recording end of the magnetic head that is in contact with a recording medium is formed, and another core portion is formed. It is formed of a second magnetic material having a saturation magnetic flux density greater than the saturation magnetic flux density of the first magnetic material, and at least a part of the joint surfaces of the first and second magnetic materials abut against the magnetic gap. In the magnetic head configured to intersect obliquely with the surface, two portions made of the second magnetic material facing each other across the magnetic gap are a bonding surface of the second magnetic material to the first magnetic material. The outer circumferential surfaces facing the bonding surfaces are configured to intersect diagonally with respect to the abutting surfaces of the magnetic gap while maintaining a distance therebetween that does not substantially exceed the width of the abutting surfaces. It is characterized by:

The present invention will be described in detail below with reference to the drawings.

As is clear from the above description of the conventional magnetic alloy film ferrite composite magnetic head, the drawback of this type of conventional composite magnetic head is that the bonding surface between the magnetic alloy film and the ferrite is parallel to the abutting surface of the head gap. Therefore, in the magnetic head of the present invention, even though the presence of such a bonding surface is unavoidable, its presence does not cause the magnetic effect as described above. In order to avoid affecting the characteristics of the head,
The structure is such that the joint surface is not parallel to the abutting surface of the headgap, for example, the third
The structure is as shown in Figures a to c.

In the structural examples of the magnetic heads of the present invention shown in FIGS. 3a to 3c, the bonding surface S between the magnetic alloy film m and the ferrite F is in the direction of the opposing surface of the head gap g, that is, in the direction of the magnetic recording medium. The arrangement is made obliquely to the direction perpendicular to the relative running direction, at least to prevent the formation of an undesired effective head gap due to the opposing joint surfaces.

Next, among the structural examples shown in the third figure, especially the third
FIG. 3C shows a side view of the structure example whose top view is shown in FIG.

That is, in the manufacturing process of the magnetic head of the present invention, first, as shown in FIG. 4a, a roof shape with continuous triangles is formed on the part above the winding window w of the head core shown in FIG. 3c. A magnetic alloy m such as sendust alloy is deposited on the roof-shaped part of the ferrite block by a conventional thin film manufacturing method such as sputtering, and the bonding surface and outer peripheral surface of the magnetic alloy film are coated on the roof-shaped part of the block. as shown in Figure 4b, or as shown in Figure 3a,
A composite magnetic block is fabricated in parallel as shown in b. Then, as shown in the figure, a magnetic alloy film m
The apex part of the chiseled roof shape is ground to form the abutting surface p of the head gap. At that time, the track width w, which is determined by the width of the abutting surface p in the final finished state, is determined by the thickness of the alloy film m and the amount to be polished, and the bonding between the ferrite block and the magnetic alloy film is determined. The distance between the surface and the outer peripheral surface of the magnetic alloy film should not exceed the width of the abutting surface p. Next, a silicon oxide film G is applied to the abutting surfaces of the head gap formed by the polishing described above to a thickness of, for example, about 0.2 to 0.5 μm.
For example, a composite magnetic block that forms one side of the head chip is formed by applying high-frequency sputtering.
Produce F ₁ .

Next, the composite magnetic block F ₂ forming the other side of the head chip is formed completely symmetrically so that the abutting surfaces p coincide with each other, and a winding window w is provided, and the composite magnetic block F 1 described above is brought into contact with the composite magnetic block F ₁ . They are arranged as shown in Figure 4c and welded to each other at the back gap B using, for example, glass.

Next, the composite magnetic blocks F ₁ and F ₂ welded as described above are cut into blocks of the triangular roof as shown by dotted lines in FIG. 4c to produce a large number of composite magnetic heads.

Finally, each composite magnetic head created as described above is provided with a winding window w as shown in FIG. 3c.
The coil c is wound around each block F ₁ and F ₂ through the magnetic head to complete a magnetic head.

An example of the method and conditions for forming the magnetic alloy film described above is as follows.

Deposition method: DC sputtering method Magnetized alloy: Sendust (Fe, Si, Al) alloy Argon gas pressure: 1 to 2 x 10 ^-3 Torr Target voltage: 1000V Ferrite temperature during _DC deposition: 350 to 400°C The magnetic alloy film described above can also be formed by other thin film manufacturing methods, such as high frequency sputtering, vapor deposition, plating, etc.
The magnetized alloy may also be a permalloy (Ni, Fe) alloy, an alperm (Fe, Al) alloy, or the like.

As is clear from the above description, according to the present invention, the above-mentioned drawbacks that have conventionally occurred in magnetic heads made of composite magnetic materials having bonding surfaces of different magnetic materials with different effective magnetic permeabilities in the vicinity of the head gap can be solved. The deterioration of characteristics due to undesired peaks and dips in the reproduced output-frequency characteristics caused by an undesired equivalent head gap due to the joint surface of the head gap can be avoided by simply changing the direction of the joint surface from the conventional one and intersecting the head gap at an angle. By simply arranging them in such a way, they can be removed all at once and a composite magnetic head with good characteristics can be realized.

Furthermore, according to the present invention, the distance between the bonding surface of the magnetic alloy film to the ferrite block and the outer peripheral surface is narrowed, and the thickness of the second magnetic material is significantly thinner than in the past. Not only does it become easier to deposit and form a magnetic alloy film, but the loss due to high frequency eddy currents that tend to occur in this type of magnetic alloy film is significantly reduced.

Furthermore, the bonding surface described above extends obliquely to the relative running direction of the magnetic recording medium in contact with the magnetic head, and the strong contact pressure causes mechanical damage to the magnetic recording medium running in contact with the magnetic head. Since sufficient strength is obtained, there is no risk of creating an undesired gap at the joint surface unlike in the past, and
By appropriately setting the amount of magnetic alloy film deposited and the amount of polishing during the manufacturing process, the track width of the head gap in the finished state can be easily adjusted to the desired value, and the characteristics of the composite magnetic head, especially , the regeneration efficiency can be further improved.

[Brief explanation of drawings]

Figures 1a and b are top and side views showing the structure of a conventional composite magnetic head, respectively, and Figure 2a is a
- c are characteristic curve diagrams respectively showing the reproduction output-frequency characteristics, Figs. 3 a, b and c are top and side views showing structural examples of the magnetic head of the present invention, respectively, and Figs. 4 a - c are the same. It is a perspective view which shows the manufacturing process sequentially. F, F ₁ , F ₂ ... ferrite (block), m...
...Magnetic alloy film, g...Head gap, B...Back gap, w...Window window, c...Coil, S
...joint surface, G...joint surface interval, W...track width, p...butt surface.

Claims (1)

[Scope of Claims] 1. Of the magnetic cores constituting the magnetic path in the magnetic head, a core portion constituting a magnetic gap at a recording end of the magnetic head that is in contact with a recording medium is replaced by a core portion constituting a magnetic gap forming another core portion. a second magnetic material having a saturation magnetic flux density greater than the saturation magnetic flux density of the first magnetic material, and at least a part of the joint surface of the first and second magnetic materials is an abutting surface of the magnetic gap. In the magnetic head, two portions made of the second magnetic material facing each other across the magnetic gap are arranged to intersect obliquely with the second magnetic material.
The bonding surface of the magnetic material to the first magnetic material and the outer circumferential surface opposite to the bonding surface are spaced apart from each other with respect to the abutting surface of the magnetic gap that does not substantially exceed the width of the abutting surface. A magnetic head characterized in that it is configured so that each head crosses obliquely when the two heads are held in the same position. 2. A magnetic head according to claim 1, wherein the first magnetic material is ferrite, and the second magnetic material is a magnetic alloy thin film.