JPS6363106A - Magnetic head - Google Patents

Abstract

PURPOSE:To reduce sliding noise at the time of reproducing to a greater extent and to obtain an excellent reproduced image by constituting an oxide magnetic material of a polycrystalline material having <=1X10<-6> absolute value of magnetostriction constant. CONSTITUTION:The oxide magnetic material of a magnetic head of a composite type formed by constituting magnetic core half bodies of the oxide magnetic material and thin magnetic alloy film is formed of the polycrystalline material and the absolute value ¦lambdas¦ of the magnetostriction constant lambdas thereof is specified to <=1X10<-6>. The use of the polycrystalline material as the oxide magnetic material of the composite type magnetic head is advantageous in terms of the magnetostriction constant lambdas and more particularly the sliding noise is reduced to a greater extent by selecting the material consisting of the compsn. having <=1X10<-6> absolute value ¦lambdas¦ thereof.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic head suitable for recording and reproducing information on a high coercivity magnetic recording medium such as a so-called metal tape. The present invention relates to a magnetic head made of a composite magnetic material of an oxide magnetic material and a magnetic alloy thin film.

[Summary of the invention]

The present invention provides a composite magnetic head in which a magnetic core is composed of an oxide magnetic material and a magnetic alloy thin film, in which the oxide magnetic material is made of a magnetostriction constant (λs) having an absolute value (1
By using a polycrystalline material with λst) of lXl0-6 or less, it is possible to significantly reduce sliding noise during reproduction and obtain excellent reproduced images.

[Conventional technology]

In recent years, equipment such as video tape recorders has become smaller.

With the demand for long-duration recording and the advent of so-called digital video tape recorders, high-density recording and short-wavelength recording have been promoted, and in response, high-coercivity magnetic recording media have come into use. There is.

Along with this, there is an increasing demand for improved performance of magnetic heads. Under these circumstances, a composite magnetic material consisting of an oxide magnetic material (ferrite, etc.) and a magnetic alloy (Fe-A6-3 i-based alloy, etc.) was used as the magnetic core material, and the magnetic alloy'gt films were butted together. It is well known that a so-called composite magnetic head in which a portion of the magnetic head is used as an operating gap has been proposed and put into practical use.

That is, the above-mentioned composite magnetic head has Fe-Ajl-3i, which is a high saturation magnetic flux density material near the working gap.
Most of the other material is made of ferrite, which is a high magnetic permeability material.

Therefore, during recording, the magnetic head exhibits the same characteristics as if the entire magnetic head were made of a high permeability material, and sufficient recording can be performed even on a high coercive force magnetic recording medium, and during playback, the magnetic head It has a structure that exhibits good electromagnetic conversion characteristics because of its high average magnetic permeability.

[Problem that the invention seeks to solve]

However, as described above, the magnetic head using ferrite for the magnetic core has the problem that so-called sliding noise occurs during reproduction, making it impossible to obtain a good reproduced image.

The above-mentioned sliding noise strongly depends on the magnetostriction of the magnetic core material, and elastic vibrations are transmitted from the recording medium to the head, and this vibration generates an inverse magnetostrictive effect, causing changes in magnetic flux, which are detected as noise by the coil. It is.

Single-crystal ferrite, which has conventionally been widely used as a core material, has a large absolute value of its magnetostriction constant, so reducing the sliding noise is a major issue in magnetic heads using this ferrite. In particular, in the above-mentioned composite magnetic head, the influence of the magnetic alloy thin film material, bonding material, etc., and the influence of the above-mentioned sliding noise become even more pronounced.
This improvement is urgently needed.

The present invention was proposed in view of the above circumstances, and aims to provide a magnetic head that has extremely low sliding noise during reproduction and exhibits good recording and reproduction characteristics for high coercive force magnetic recording media. purpose.

[Means for solving problems]

The inventors of the present invention have conducted intensive research over a long period of time to achieve the above-mentioned purpose, and have found that the above-mentioned sliding noise can be effectively eliminated by using a polycrystalline material with a magnetostriction constant within a predetermined range as an oxide magnetic material. We discovered that it is possible.

The present invention was completed based on such knowledge,
In a composite magnetic head in which a magnetic core is composed of an oxide magnetic material and a magnetic alloy thin film, the oxide magnetic material is made of a polycrystalline material, and the absolute value (1λ31) of the magnetostriction constant (λs) is I. It is characterized by being equal to or less than X 10-'.

[Effect]

In the above polycrystalline oxide magnetic material, the magnetostriction appearing externally is averaged over all the small crystal grains, so it appears isotropic. The magnetostriction constant λs at this time is the magnetostriction constant λ1° in the (100) direction of the single crystal oxide magnetic material. and the magnetostriction constant λ in the (111) direction, 1, can be expressed as in the following equation.

Here, the above λ1°. and λ,, are never 0, and λ1゜. <O (shrinks in the magnetization direction), λ1.1>0
(extends in the magnetization direction).

Therefore, the absolute value (1λ31) of the magnetostriction constant λs of the polycrystalline oxide magnetic material is equal to the absolute value 1λs of the strain constant of the single crystal oxide magnetic material. . 1. ) is always smaller than λ51111.

That is, using a polycrystalline material as the oxide magnetic material of the composite magnetic head is advantageous in terms of the magnetostriction constant λs, and in particular, by selecting a material with a composition whose absolute value 1λs1 is 1XIO-h or less, Sliding noise is significantly reduced.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an example of a magnetic head to which the present invention is applied, and FIG. 2 is an enlarged plan view of the main part showing the sliding surface of the magnetic recording medium.

In this magnetic head, the magnetic core half (1), (
The magnetic core portions (11) and (12) occupy the majority of the
are made of an oxide magnetic material with a polycrystalline structure, and the inclined surfaces (lla) and (12a), which are diagonally cut out from the bonding surfaces of these magnetic core parts (11) and (12), have a bank gap from the front gap surface. A magnetic alloy thin film (13^) + (13B) made of a high saturation magnetic flux density alloy, such as a Fe-A/1-3i alloy, is deposited all the way to the surface.
The magnetic core halves (1) and (n) are constructed respectively. And these pair of magnetic core halves (1),
(II) through a gap spacer such as 5ift, and form the above magnetic alloy thin films (13A) and (13B).
The abutment surface is configured to form an operating gap g with a track width T-. In addition, the above magnetic alloy thin film (13A)
, (13B) Upper and track width regulating groove (llb).

Inside (12b) are non-magnetic materials (16^), (16
B), (17A), and (17B) are melt-filled. Further, one magnetic core half (1) is provided with a winding hole (18) for winding a coil.

Here, in the present invention, a polycrystalline oxide magnetic material is used as the magnetic core parts (11) and (12).

The above-mentioned polycrystalline oxide magnetic material may be one normally used in this type of magnetic head, but Mn--Zn ferrite, Ni--Zn ferrite, etc. are particularly suitable. Further, as the polycrystalline oxide magnetic material, a so-called high-density polycrystalline structure in which the size of pinholes is small and the number of pinholes is very small is more preferable, that is, the pinholes are large (5 to 10 cm or more). ) Polycrystalline oxide magnetic materials that do not have a high density may cause pinholes to become clogged with powder from the medium during sliding contact with the recording medium, causing spacing loss and damage to the medium and contributing to noise. , head wear increases, which is undesirable.

On the other hand, with a high-density polycrystalline structure, even if there is a pinhole, it is only about 0.5μm, and the surface shakes when the medium slides into contact with it, and there appears to be no pinholes, making it stable. Head characteristics can be obtained.

In any case, in the present invention, as the polycrystalline oxide magnetic material, the absolute value 1λs1 of the magnetostriction constant λs is lX
10-' or less are used.

That is, when IASl exceeds lXl0-', the magnetic flux changes due to elastic vibrations within the magnetic core sections (11) and (12), and as a result, the sliding noise level increases, making it impossible to achieve the initial purpose.

In this way, by using a polycrystalline oxide magnetic material in which the absolute value 1λs1 of the magnetostriction constant λs is equal to or less than lXl0-r for the magnetic core parts (11) and (12), it is possible to significantly reduce the sliding noise that occurs during reproduction. . Therefore, a magnetic head with excellent reproduction characteristics can be provided.

The magnetostriction constant λs of the polycrystalline oxide magnetic material is greatly influenced by the composition of the nuclear oxide magnetic material. Therefore, the present inventors investigated each component (Fetox, ZnO, etc.) in Mn-Zn ferrite having a polycrystalline structure.

The magnetostriction constant λs was measured with various compositions of Mn0), and the composition range in which its absolute value 1λs1 was less than lXl0-'' was determined. molχ, ZnOmolχ, Mn
Omo1χ) is (54, 4, 42), (54, 24, 2
2), the polycrystalline ferrite in the region surrounded by the three points (51, 24, 25) has an absolute value Iλsl of the magnetostriction constant λs of l
It was found that Xl0-'- or less.

Next, the present inventors used Mn-Zn polycrystalline ferrite having the above composition range as the magnetic core parts (11) and (12) of the composite magnetic head shown in FIGS. 1 and 2. A head was created and the sliding noise level was measured. For comparison, the above magnetic core part (11).

(12) The sliding noise level was also measured for a magnetic head made using Mn-Zn single crystal ferrite.

The results are shown in FIG. 4 (this example) and FIG. 5 (comparative example), respectively.

The above sliding noise level is calculated by subtracting the system noise level (curve in the figure) Q b ) from the noise level when the magnetic tape is slid (curve a in the figure), and the remaining amount is the sliding noise level. (Curve C in the figure).

As is clear from FIGS. 4 and 5, it has been found that the sliding noise level during reproduction can be significantly reduced by using a multi-antagonist material as the oxide magnetic material constituting the magnetic core.

Furthermore, Mn-Zn is added to the magnetic core parts (11) and (12).
Composite magnetic heads using polycrystalline ferrite were fabricated with various magnetostriction constants λs of the polycrystalline ferrite, and their sliding noise levels were measured. The results are shown in Figure 6.

From FIG. 6, it can be seen that sliding noise has a correlation with the magnetostriction constant of polycrystalline ferrite, and magnetic heads using polycrystalline ferrite with a magnetostriction constant λs of less than lXl0-b have an extremely low sliding noise level and are good. It was found that the material exhibited excellent playback characteristics.

By the way, if a polycrystalline oxide magnetic material is used for the magnetic core, there is a concern that crystal grain agglomerates, so-called branes, may fall off during sliding contact with the medium, but in the magnetic head of this embodiment, polycrystalline oxide is used near the operating gear g. Since there is no oxide magnetic material in the structure and the magnetic alloy yi films (13A) and (13B) are provided, there is no fear of the branes falling off. Therefore, the gap length of the working gap g is stable over a long period of time, and a highly reliable magnetic head can be provided.

Furthermore, if a single crystal oxide magnetic material is used for the magnetic core parts (11) and (12), the magnetic alloy thin film (13A), (
Strain is accumulated due to the difference in thermal expansion coefficient with 13B),
Although this has been a major problem in terms of manufacturing or electromagnetic conversion characteristics, the use of an oxide magnetic material with a polycrystalline structure has the advantage that the strain can be effectively dispersed as described above.

Therefore, the magnetic core part (11).

By using a polycrystalline oxide magnetic material for (12), electromagnetic conversion characteristics and yield are significantly improved.

Furthermore, the polycrystalline oxide magnetic material can be manufactured at a cost approximately 1 to 5 times lower than that of single crystal, and at the same time, there is no platinum incorporation defect, which is a drawback in the manufacturing method of single crystal ferrite.

Therefore, it is possible to significantly reduce the manufacturing cost, and at the same time, it is possible to increase the size of the substrate, which is advantageous in terms of plate productivity.

Furthermore, since the present invention can be implemented without making any changes to the conventional head structure or manufacturing process, it can be said that its practical value is extremely high.

In the above embodiment, F is used as the magnetic base metals mHQ (13A) and (13B) forming the working gap
Although the e-Al-3i alloy is taken as an example, there are also ferromagnetic amorphous alloys, so-called ferromagnetic amorphous alloys (e.g. Fe
, Ni, Co and p, c.

An alloy consisting of one or more elements of B and Si, or an alloy containing this as a main component such as Af, Ge, Be, Sn, or In.

metal-metalloid amorphous alloys such as alloys containing Mo, W, Ti, Mn, Cr, Zr, Hf, Nb, etc.;
or metal-metal amorphous alloys whose main components are transition metals such as Co, HE, Zr, and rare earth elements),
Fe-AA alloy, Fe-3i alloy, Fe-3i-(
It may be an o-based alloy, a Ni-Fe-based alloy, a Fe-Ga-3i-based alloy, or the like. In addition, the method for attaching the film is as follows:
Vacuum thin film forming techniques such as sputtering method, vacuum deposition method, flash evaporation method, ion blating method, and cluster ion beam method can be mentioned. Further, although the magnetic alloy thin films (13A) and (13B) have a single layer structure in this example, they may be made of, for example, SiOx, Taxos,
A plurality of layers may be formed via a highly wear-resistant insulating film such as A I2 tOi, ZrO□, or 3i3Nm. In this case, the number of laminated magnetic alloy thin films can be set arbitrarily.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and can be applied to composite magnetic heads of various structures without departing from the spirit of the present invention.

For example, as shown in FIG. 7, track width regulating grooves (21, 22) for regulating the track width are located near the contact surfaces of the magnetic core parts (21) and (22) made of a polycrystalline oxide magnetic material. 21a) and (22a) are cut out, and magnetic alloy thin films wA (23) and (24) are formed on the contact surfaces including the trunk width regulating grooves (21a) and (22a). ), (24), the parallel parts (23a) and (24a) may be butted against each other to form an operating gap g. This magnetic head may have a track width Th of a thin magnetic metal Fl(23).
, (24) can be made large regardless of the film thickness, so it is suitable for a magnetic head with a wide track.

〔Effect of the invention〕

As is clear from the above description, in the present invention, in order to reduce the sliding noise generated during reproduction, a polycrystalline oxide magnetic material having a magnetostriction constant within a predetermined range and a magnetic alloy thin film are used as the magnetic core material. Since a composite magnetic material is used, it is possible to provide a magnetic head that exhibits excellent recording and reproducing characteristics. Therefore, the magnetic head to which the present invention is applied not only exhibits sufficient recording characteristics for high coercive force magnetic recording media compatible with high-density recording, but also exhibits extremely low sliding noise and good playback. An image is obtained.

Further, since the polycrystalline oxide magnetic material described above can effectively disperse strain caused by thermal strain and thermal expansion coefficient, there is no fear that cranks or the like will occur in the magnetic core during the head manufacturing process. Therefore, the magnetic properties of the oxide magnetic material or the magnetic alloy thin film are fully exhibited, resulting in a head that exhibits good electromagnetic conversion properties, and the yield is significantly improved.

Furthermore, since the polycrystalline ferrite can be produced at a lower cost than conventional single crystal ferrite, material costs can be reduced.

Further, according to the present invention, there is an advantage that the sliding noise level can be reduced without changing the manufacturing process or the head structure.

These advantages greatly contribute to the demand for improved performance of magnetic heads due to the remarkable progress of video tape recorders and the like in recent years, and make it possible to provide magnetic heads with high practical value.

[Brief explanation of drawings]

FIG. 1 is an external perspective view showing an example of a magnetic head to which the present invention is applied, and FIG. 2 is an enlarged plan view of essential parts showing the sliding contact surface of the magnetic recording medium of the magnetic head shown in FIG. 1. FIG. 3 is a ternary composition diagram of Mn--Zn polycrystalline ferrite, showing the composition range in which the magnetostriction constant is lXl0-' or less. FIG. 4 is a characteristic diagram showing the frequency characteristics of the sliding noise level of an embodiment to which the present invention is applied (using polycrystalline ferrite);
Figure 5 shows a conventional magnetic head (using single crystal ferrite)
A characteristic diagram showing the frequency characteristics of the sliding noise level is shown. FIG. 6 is a characteristic diagram showing the relationship between the magnetostriction constant and sliding noise of polycrystalline ferrite. FIG. 7 is an enlarged plan view of a main part showing the sliding contact surface of a magnetic recording medium in another structural example of a magnetic head to which the present invention is applied.

Claims (1)

[Claims] In a composite magnetic head in which a magnetic core half is composed of an oxide magnetic material and a magnetic alloy thin film, the oxide magnetic material is made of a polycrystalline material and its magnetostriction constant (λs
) has an absolute value (|λs|) of 1×10^-^6 or less.