JPH09198609A - Magnetic head - Google Patents

Abstract

(57) Abstract: A magnetic head having high reproduction output and less noise is provided. A main magnetic core 221 is formed of a soft magnetic ferrite material, a magnetic gap g that is in sliding contact with a magnetic recording medium is formed of a soft magnetic ferrite material, and a track width end of a magnetic gap portion g extends from inside the track width regulating groove. The soft magnetic metal film 25 is formed so as to cover the entire portion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head used in a magnetic recording / reproducing apparatus such as a video tape recorder or a computer data storage. More specifically, the present invention relates to a magnetic head suitable for use in a magnetic recording / reproducing apparatus having a structure that requires a specific signal frequency band.

[0002]

2. Description of the Related Art Conventionally, a soft magnetic oxide magnetic material such as Mn-Zn or Ni-Zn, a ferrite head having a so-called ferrite as a magnetic core, has been used as a magnetic head due to its excellent wear resistance. . Due to the high coercive force and high saturation magnetic flux density of the corresponding magnetic tape, in the field of using a magnetic head for both recording and reproducing, replacement with a MIG (metal-in-gap) head, which can obtain a larger magnetic field in the gap, has been promoted. However, the ferrite head has been reexamined in recent years due to the advantage that the output is superior to the MIG head, and the recording / reproducing head separation system, which can be combined with the recording using the MIG head and using the ferrite head with good output only for reproduction, is higher. Ferrite heads have come to be used again in the field of high recording density magnetic recording requiring output.

However, the output of the ferrite head is MI.
Although it is superior to the G head, it also has a drawback that the noise becomes larger than that of the MIG head. The increase in the output is canceled by the noise mainly due to the increase in the sliding noise and the second harmonic distortion noise, and the output alone is I am not able to fully utilize the rate of improvement in the playback output of the ferrite head.

[0004]

As described above, in the field of magnetic recording, the separation of recording and reproduction of the magnetic head has been advanced in response to high density recording, and particularly high output as a reproducing head has been achieved. A ferrite head which is obtained and which is inexpensive to manufacture is about to be used. However, the ferrite head can obtain a higher output than the MIG head whose magnetic path is composed of ferrite and a soft magnetic metal film, but has a problem of increasing noise.

In view of the above points, the present invention provides a magnetic head having high output and low noise.

[0006]

In a magnetic head according to the present invention, a magnetic gap portion that is in sliding contact with a magnetic recording medium is formed of a soft magnetic oxide magnetic material, and a track width end of the magnetic gap portion extends from the inside of the track width regulating groove. A soft magnetic metal film is formed over the portion.

Since the magnetic gap portion that is in sliding contact with the magnetic recording medium is formed of a soft magnetic oxide magnetic material, high reproducing efficiency is exhibited, while the soft magnetic property extends from the track width regulating groove to the track width end portion of the magnetic gap portion. Since the metal film is deposited and formed, noise is suppressed due to the effect that part of the magnetic flux flows through the soft magnetic metal film.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A magnetic head according to the present invention, particularly a magnetic head for reproduction, has a main magnetic core formed of a soft magnetic oxide magnetic material, and has a magnetic gap portion which is in sliding contact with a magnetic recording medium, that is, a sliding surface. The main track width portion on the magnetic gap surface in the vicinity of the moving surface is formed of a soft magnetic oxide magnetic material, and a soft magnetic metal film is formed by adhesion from inside the track width regulating groove to the track width end portion of the magnetic gap. And

In the magnetic head according to the present invention, the soft magnetic metal film deposited on the soft magnetic oxide magnetic material forms a substantially closed magnetic path along the inner surface of the winding groove.

An embodiment of the magnetic head of the present invention will be described below with reference to the drawings.

1 and 2 show an example of a magnetic head according to the present invention. The magnetic head will be described together with its manufacturing method. First, as shown in FIG. 3, Mn-Zn or N
A substrate 21 made of a soft magnetic oxide magnetic material of i-Zn, a so-called soft magnetic ferrite material is prepared. This soft magnetic ferrite substrate 21 has a length of 45 mm and a width of 45 mm so that, for example, 14 core half blocks can be obtained from this substrate 21.
B. It is formed to have a thickness of 1 mm. This soft magnetic ferrite substrate 21 is used for AA ', BB', CC ', D-
Cut along the line of D ', for example, 45 mm in length x 2.5 in width
A plurality of core half blocks 22 having a size of mm × 1 mm is formed.

Next, as shown in FIG. 4, a track width regulating groove 23 having a substantially U-shaped cross section is formed in a predetermined manner so that a prescribed track width Tw remains on the main surface 22a of the core half block 22. Form with a pitch. In this example, the angle of the contact portion with respect to the main surface 22a is set to 60 °, and for example, the width t of the groove opening portion is set.
₁ is 190 μm, depth h ₁ is 95 μm, and the remaining track width Tw is 16 μm, which is a substantially U-shaped groove 23. The shape of the groove 23 may be a rectangular shape including a vertical surface and a horizontal surface, or a V shape.

Next, as shown in FIG. 5, a winding groove 24 is formed on the main surface 22a of the core half block 22 perpendicularly to the track width regulating groove 23. In this example, the opening width t ₂ is 6
A substantially pentagonal shape having a depth of 50 μm, a depth h ₂ of 200 μm, an angle of 40 ° to the main surface 22a at the end close to the sliding surface, and an angle of 90 ° to the main surface 22a at the opposite end. A winding groove 24 having a cross-sectional shape of After that, polishing is performed so that the surface roughness of the portion having the track width Tw remaining on the main surface 22a becomes about 50 nm.

Next, as shown in FIGS. 6A and 6B, one main surface 22a of the core half block 22 and the track width regulating groove 2 are formed.
3. A soft magnetic metal film 25 is formed on the entire surface including the winding groove 24 by a method such as sputtering via a reaction preventive film 32 made of, for example, SiO ₂ , platinum or the like.

As shown in FIG. 6A for the purpose of the present invention, a soft magnetic metal film 25 is formed inside the winding groove 24 to form a front gap surface on the sliding surface side (so-called gap butt surface). It is desirable to form the soft magnetic metal film 25 from 26 to the rear gap surface (so-called gap abutting surface) 27 at the rear of the winding groove 24, but the winding groove 2
4) If the magnetic characteristics of the soft magnetic metal film 25 in the inside 4 are such that sufficient magnetic characteristics cannot be obtained due to the angle of the groove forming surface of the substrate, the surface roughness of the processed surface, etc. Even if the soft magnetic metal film 25 is formed so as to be partially interrupted, the effect of the present invention is reduced, but it does not depart from the gist of the present invention.

As the soft magnetic metal film 25, sendust,
FeGaSiRu, an amorphous material, or a microcrystalline soft magnetic material containing nitrogen, carbon, boron, etc. is generally M
The soft magnetic metal material used for the IG head can be used.

Next, as shown in FIGS. 7A and 7B, the gap surfaces 26 and 27 are polished to form the gap surfaces 26 and 27.
The soft magnetic metal film 25 and the reaction preventive film 32 formed on the above are removed. That is, polishing is performed until the ferrite surface is exposed, and the gap surfaces 26 and 27 are formed so that the surface roughness is 100 Å or less.

Next, as shown in FIG. 8, a pair of similarly formed core half blocks 22A and 22B are provided with gap spacers so that the track widths Tw of the gap surfaces 26 and 27 coincide with each other. Align through and match. Then, glass 29 is poured so as to fill the track width regulation groove 23 to bond the core half blocks 22A and 22B. Then, with the azimuth according to the specifications of the format using the head, a-
The head chip alone is obtained by cutting along the lines a ', bb', cc ', d'd' and ee '.

Next, the sliding surface 30 is formed by cylindrical grinding to obtain the target magnetic head 31 shown in FIGS.

That is, the magnetic head 31 shown in FIGS.
Indicates that a pair of ferrite core halves 221A and 221B are joined via a gap spacer to form a magnetic gap g between the abutting surfaces thereof, and the gap surfaces of the front gap and the rear gap, that is, the abutting surfaces are Except for this, the metal magnetic film 25 is formed so as to reach the sliding surface 30 along the winding groove 24 and the track width regulation groove 23 and to cover the track width end of the magnetic gap g. As a result, a magnetic path that is continuous along the inner surface of the winding groove 24, that is, a closed magnetic path is formed only by the metal magnetic film 25.

The track width regulating groove 23 is filled with glass 29, and the ferrite core half body 221A,
A reaction preventing film 32 for preventing mutual reaction is formed between the 221B and the metal magnetic film 25.

According to the magnetic head 31 of the above embodiment,
The main magnetic core 221 is made of soft magnetic ferrite,
Since the track width portion of the sliding surface 30, that is, the magnetic gap g is composed of a ferrite core, a high reproduction output can be obtained. On the other hand, since the soft magnetic metal film 25 forms a closed magnetic path independently of the ferrite core, a part of the magnetic flux flows through the soft magnetic metal film 25, so that the generation of noise can be suppressed.

10 and 11 show a second embodiment of the magnetic head of the present invention. In the above-described magnetic head 31 of the first embodiment, the ends of the track width in the magnetic gap g are formed by the soft magnetic metal film 25. However, in the magnetic head 41 of the second embodiment, the soft ends at both ends are formed. Magnetic metal film 25
Is further cut toward the gap surface, and the track width portion of the magnetic gap g is composed only of ferrite. The other structure is similar to that of the first embodiment shown in FIGS.

In the second embodiment, as shown in FIG. 11A, after the processing corresponding to FIG. 7A of the first embodiment is performed, the soft magnetic metal film 23 remaining on the side surface of the track width is ground. Perform processing. This grinding substantially eliminates the soft magnetic metal film 23 at the track width end of the gap surface. Further, when the grinding angle θ (see FIG. 11B) of the soft magnetic metal film 23 is large, the azimuth of adjacent tracks on the tape is reduced. It becomes an angle close to and easily causes noise such as crosstalk,
If the depth is shallow, the effect of reducing sliding noise and harmonic noise due to the formation of the magnetic film, which is the gist of the present invention, is reduced. From this, the grinding angle θ is preferably about 20 ° to 60 °.

Next, a comparison between the MIG head and the ferrite head and the magnetic head of the present invention will be shown. Regarding a MIG head, a ferrite head, and a magnetic head of the present invention, in which only a specific single frequency is recorded on a metal tape by using an MIG head, they are formed to have substantially the same size, and windings are formed so as to have the same inductance, FIG. 12 shows the frequency components of the output obtained in the wide frequency range of the reproduced signal. In FIG. 12, the spectra obtained by each head are shifted in the horizontal axis direction so that the peaks do not overlap so that they can be seen easily. Curve I is amplifier noise, curve II is M
IG head, curve III shows the output of the magnetic head of the present invention, and curve IV shows the output of the ferrite head.

The ferrite head (curve IV) has a higher reproduction output than the MIG head (curve II) for a single recorded frequency, as shown by the head output in the figure. This difference is about 5 when the tape used in 8 mm video is used and the recording frequency is 5 MHz at a head-tape relative speed of 3.8 m / s.
dB.

On the other hand, when the ratio of the reproduced signal of 10 MHz which is the second harmonic component to the original signal of 5 MHz is measured, the ratio of the second harmonic in the ferrite head (curve IV) is the same as that in the MIG head. It was found that it was about 2 dB larger than that. Furthermore, when the difference between the output level, which is called oscillation noise, when the head is not slid on the tape and the output in the frequency band where the original reproduced waveform when sliding is not obtained is measured, the ferrite head (curve IV) is about 3d compared to MIG head (curve II)
The level when sliding about B is high. From these results, in the case of a system that is susceptible to noise in the noise generation band and signal processing, the improvement in the reproduction output of the ferrite head is canceled by the noise,
In some cases, the MIG head and the signal-to-noise (S / N) component were equal to each other.

Next, when only the magnetic film on the gap surface of the MIG head is removed to form the magnetic head structure of the present invention, as shown by the curve III, the head output is 4 dB better than the MIG head, and the noise is MIG. 2 compared to the head
It was found that both the second harmonic distortion and the sliding noise were suppressed by the deterioration of about 1 dB, respectively, and as a result, the S / N was improved by 2 to 3 dB as compared with the MIG head and the ferrite head.

The cause of this is considered as follows. MIG
In the case of the head, the magnetic property of the ferrite portion on which the metal magnetic film is formed due to the formation of the metal magnetic film is deteriorated due to the stress and strain due to the formation, but in the case of the magnetic head of the present invention, this is improved To be done. Further, the soft magnetic metal film causes less noise generation when transmitting magnetic flux than ferrite does. Therefore, in the case of the magnetic head of the present invention, the soft magnetic metal film acts as an auxiliary magnetic path to suppress noise generation. It

Further, in the case of a ferrite head, when a narrow track and a narrow gap length are obtained, the reaction is promoted at a high temperature during glass fusing, and as a result, the gap film is eroded by the glass at the track width end, and subsequently the glass is eroded. Corrosion of ferrite occurs due to, and the ferrite component dissolved in the glass causes reprecipitation in the cooling process of fusion. As a result, the magnetic insulation deteriorates at both ends of the gap, and the magnetic flux directly passing between the cores increases without passing through the tape in the gap. This may result in reduced efficiency,
In the case of the above-described first embodiment and the second embodiment, a small amount of metal magnetic film is left on both ends of the magnetic gap g (0.5 to
(About 1.0 μm), the magnetic gap g
Both ends of the magnetic field are metal magnetic films 23, and the efficiency of the head is improved as compared with the ferrite head.

That is, it becomes difficult for erosion and reprecipitation by glass to occur, and the ferrite portion in the center of the gap has a small capacity of contacting the ferrite of the glass, and is a chemically polished polished surface, which is a functional area of glass-ferrite. Is less per unit volume, and since it is a flat surface, a chemical reaction is less likely to occur, and as a result, a magnetically good gap between cores is easily formed, and the magnetic resistance of the gap portion increases. This also has the effect of improving the efficiency of the head due to the gap as compared with the case of a ferrite head.

[0032]

According to the magnetic head of the present invention, it is possible to obtain a magnetic head having high reproduction output and less noise. That is, a magnetic head having high signal-to-noise characteristics can be obtained. Moreover, it is possible to stably manufacture in a simple manufacturing process.

Therefore, it is suitable for use in a magnetic head of a magnetic recording / reproducing apparatus having a structure requiring a specific signal frequency band.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a magnetic head according to the present invention.

FIG. 2 is a plan view seen from the sliding surface side of FIG.

FIG. 3 is a manufacturing process drawing of a first embodiment of a magnetic head according to the present invention.

FIG. 4 is a manufacturing process diagram of a magnetic head according to a first embodiment of the invention.

FIG. 5 is a manufacturing process diagram of a first embodiment of a magnetic head according to the present invention.

FIG. 6A is a manufacturing process diagram of a magnetic head according to a first embodiment of the invention. 6B is an enlarged view of the main part of FIG. 6A. FIG.

FIG. 7A is a manufacturing process diagram of a magnetic head according to a first embodiment of the invention. 6B is an enlarged view of the main part of FIG. 6A. FIG.

FIG. 8 is a manufacturing process diagram of a first embodiment of a magnetic head according to the present invention.

FIG. 9 is a perspective view showing a second embodiment of the magnetic head according to the present invention.

10 is a plan view seen from the sliding surface side of FIG. 9. FIG.

FIG. 11A is a manufacturing step diagram of the magnetic head according to the second embodiment of the present invention. B is an enlarged view of a main part of FIG. 11A.

FIG. 12 is a head characteristic diagram showing a comparison of head output, sliding noise, and second harmonic noise between the magnetic head of the present invention and a conventional magnetic head.

[Explanation of symbols]

 21 ferrite substrate 22 core half block 23 track width regulation groove 24 winding groove 25 soft magnetic metal film 211 ferrite core 221A, 221B ferrite core half g magnetic gap 30 tape sliding surface

Claims (2)

[Claims] 1. A main magnetic core is formed of a soft magnetic oxide magnetic material, a magnetic gap portion that is in sliding contact with a magnetic recording medium is formed of the soft magnetic oxide magnetic material, and the magnetic gap portion is formed from inside a track width regulating groove. A magnetic head formed by depositing a soft magnetic metal film over the end portion of the track width. 2. The soft magnetic metal film deposited on the soft magnetic oxide magnetic material forms a substantially closed magnetic path along the inner surface of the winding groove. Magnetic head.