JPH05101327A - Magnetic head - Google Patents

Abstract

(57) [Abstract] [Structure] Oxide magnetic materials 1 and 2 and metal magnetic thin films 3 and 4
A pair of magnetic core halves 5 and 6 and a metal magnetic thin film 3,
In a magnetic head having a magnetic gap g formed by abutting four of them, the film thickness of the metal magnetic thin film 3 disposed on the inlet side with respect to the running direction of the magnetic recording medium across the magnetic gap g is on the outlet side. It is made thinner than the film thickness of the metal magnetic thin film 4 to be arranged. [Effect] The step difference in the magnetic gap portion due to uneven wear can be reduced, and the spacing loss can be significantly reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head mounted on, for example, a video tape recorder (VTR).

[0002]

2. Description of the Related Art In recent years, in the field of magnetic recording, the density of recording signals has been increasing, and magnetic recording media having high coercive force and high residual magnetic flux density have been used. Along with this, the core material of the magnetic head is required to have a high saturation magnetic flux density and a high magnetic permeability.

However, ferrite, which is the most widely used oxide magnetic material as the core material, has an insufficient saturation magnetic flux density. Therefore, for example, a so-called metal-in-gap type magnetic head has been proposed in which ferrite is used as an auxiliary core material, and a thin film made of a metal magnetic material having a high saturation magnetic flux density is provided as a main core material in the magnetic gap portion. Has been converted.

However, in the metal-in-gap type magnetic head, uneven wear occurs due to the difference in hardness of materials, and a step is formed on the sliding surface. That is, the sliding surface of the magnetic recording medium is gradually abraded by the sliding contact with the magnetic recording medium, but a metal material having a relatively lower hardness than ferrite wears more severely than the ferrite. In particular, when used in a dusty place, uneven wear becomes more remarkable.

Here, a problem in the magnetic head is a step in the magnetic gap portion. The larger the step, the larger the spacing loss, and the lower head output and the lower image quality. .. Therefore, it is very difficult to deal with a video tape recorder or the like that requires high definition. Although the step difference in the magnetic gap portion varies depending on the types of ferrite and metal material,
Larger particles may reach 0.3 to 0.5 μm, and some of them are unbearable in terms of deterioration of image quality.

[0006]

SUMMARY OF THE INVENTION Therefore, the present invention has been proposed to solve the above-mentioned technical problems, and reduces the step difference in the magnetic gap portion due to uneven wear and reduces the spacing loss. It is an object of the present invention to provide a magnetic head with high head efficiency and high image quality.

[0007]

In order to achieve the above-mentioned object, the present invention provides a magnetic gap between a pair of magnetic core halves made of an oxide magnetic material and a metal magnetic thin film, the metal magnetic thin films being butted against each other. In the magnetic head having the above structure, the thickness W of the metal magnetic thin film disposed on the inlet side and the thickness H of the metal magnetic thin film disposed on the outlet side with respect to the traveling direction of the magnetic recording medium across the magnetic gap. Ratio of 2 <H / W
It is characterized in that ≦ 10.

[0008]

[Function] For example, a metal-in-gap type magnetic head in which a magnetic core half body made of a metal magnetic thin film and ferrite having the same film thickness are butted against each other through a gap film is mounted on a video tape recorder. In the case of recording / reproducing, the metal magnetic thin film and the outlet side (hereinafter referred to as the leading side) disposed on the inlet side (hereinafter referred to as the leading side) with respect to the traveling direction of the magnetic recording medium (the arrow X direction in the figure) across the magnetic gap. ,
Write as the trailing side. The abrasion of the metal magnetic thin film arranged in () is asymmetric. That is, the trailing side is worn more than the leading side.

However, in the present invention, the magnetic gap position is shifted to the leading side, that is, the thickness of the metallic magnetic thin film on the leading side is made smaller than that of the metallic magnetic thin film on the trailing side. The step difference in the portion is reduced, the spacing loss is reduced and the head output is improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described in detail below with reference to the drawings. As shown in FIGS. 1 and 2, the magnetic head of this embodiment mainly includes auxiliary core portions 1 and 2 made of an oxide magnetic material such as ferrite and metal magnetic thin films 3 and 4 made of a ferromagnetic material. A pair of magnetic core halves 5 and 6 as constituent elements are joined and integrated.

Magnetic gap g in this magnetic head
Is constituted by sandwiching the metal magnetic thin films 3 and 4 with each other by sandwiching a gap film 7 made of fused glass or a non-magnetic film. The track width Tw of the magnetic gap g is regulated by the facing width of the metal magnetic thin films 3 and 4 that are abutted against each other.

The auxiliary core portions 1 and 2 constituting the magnetic core halves 5 and 6 are made of, for example, Mn-Zn ferrite or Ni-Zn ferrite, and a coil is provided on the abutting surface of one of the auxiliary core portions 1. A winding groove 8 for winding is provided. The winding groove 8 is formed as a groove having a substantially U-shaped cross section, and the depth of the magnetic gap g is regulated by the inclined surface 8a provided on the magnetic gap g side.

On the other hand, the metal magnetic thin films 3 and 4 are formed as a continuous film from the front portion where the magnetic gap g is formed to the back portion side including the inside of the winding groove 8.
Therefore, in this magnetic head, the metal magnetic thin films 3 and 4 are abutted and joined together to form a closed magnetic path by the auxiliary core portions 1 and 2 and the metal magnetic thin films 3 and 4.

As the magnetic material used for the metal magnetic thin films 3 and 4, a ferromagnetic alloy material having a high saturation magnetic flux density and an excellent soft magnetic property is used. Any conventionally known one can be used,
It does not matter whether it is crystalline or amorphous. For example, Fe-
Ni-based alloys, Fe-C-based alloys, Fe-Al-Si-based alloys, Fe-Ga-Si-based alloys, Fe-Al-Ge-based alloys, Fe-Ga-Ge-based alloys, Fe-Si-Ge-based alloys, Fe-Co-Si based alloy, Fe-Co-Si-Al
Crystalline alloy materials such as series alloys, and so-called amorphous alloys (for example, one or more elements of Fe, Ni, Co and P,
An alloy consisting of one or more elements of C, B, Si, or Al, Be, Sn, In, Mo
Metal-metalloid amorphous alloys such as alloys containing W, Ti, Mn, Cr, Zr, Hf, Nb, etc., alloys containing a transition element as a main component such as Co-Zr, Co-Hf, or rare earths Metal-metal amorphous alloys such as alloys with added elements. ) Etc. In this example, a Co-Zr type amorphous alloy was used.

As a method for forming the metal magnetic thin films 3 and 4, the PVD technique represented by a vacuum vapor deposition method, a sputtering method, an ion plating method or the like is adopted. The metal magnetic thin films 3 and 4 may be single-layer films, but for the purpose of further increasing the output in the high band, for example, SiO ₂ , Ta ₂ O ₅ , Al ₂ O ₃ , ZrO ₂ , Si.
_A multilayer film may be formed through an insulating film such as ₃ N ₄ .

Particularly, in the magnetic head of this embodiment, the film thickness of the metal magnetic thin films 3 and 4 is asymmetrical across the magnetic gap g. That is, the film thickness W of the metal magnetic thin film 3 on the leading side with respect to the film thickness H of the metal magnetic thin film 4 on the trailing side with respect to the traveling direction of the magnetic recording medium across the magnetic gap g (direction of arrow X in FIG. 2). It is made thin. This is because the step difference in the magnetic gap portion caused by the uneven wear of the auxiliary core portions 1 and 2 and the metal magnetic thin films 3 and 4 due to the hardness difference is made as small as possible, and the thickness ratio is 2 <. The range is H / W ≦ 10.

The range of the film thickness ratio can be obtained from the following experimental results. That is, as shown in FIG. 3, magnetic core halves 55 and 56 made of metal magnetic thin films 51 and 52 and ferrites 53 and 54 having the same thickness are abutted to each other via the gap film 57. Metal In
A gap type magnetic head was used, and this was mounted on a video tape recorder, and repeatedly run for 3 days outdoors in a dusty atmosphere. And a surface shape measuring instrument (model name α-ste
Scan and measure the sliding surface according to p). The result is shown in FIG. From FIG. 3, the metal magnetic thin film 51 disposed on the inlet side and the metal magnetic thin film 52 disposed on the outlet side with respect to the traveling direction of the magnetic recording medium (direction of arrow X in the figure) across the magnetic gap g are It can be seen that the wear is asymmetric.
That is, the metal magnetic thin film 52 on the trailing side is worn more than the metal magnetic thin film 51 on the leading side. In the measurement, Co—Zr type amorphous alloy was used for the metal magnetic thin films 51 and 52, Mn—Zn ferrite was used for the ferrites 53 and 54, and the film thickness of each was set to 7.5 μm. The video tape recorder is manufactured by Sony, model name Betacam-S.
P was used and the tape was trade name BCT-20G.

Next, the change in the separation loss Ls when the position of the magnetic gap g was moved to the leading side was examined. The result is shown in FIG. In addition, x shown on the horizontal axis in FIG.
Indicates the film thickness of the metal magnetic thin films 51 and 52 in FIG. 3, and the zero position indicates that the film thickness of the metal magnetic thin film 51 on the leading side is zero. Further, the separation loss Ls has a wavelength λ of 0.
7 μm and Ls = −54.6 (d / λ) [dB] (where d represents the distance between the medium and the head surface).

As can be seen from FIG. 4, the separation loss Ls is 5
If the output decreases by more than dB, the image quality becomes unbearable. Therefore, if a film thickness of 5 dB or less is selected, the thickness becomes 5 μm. At this time, the ratio of the film thickness W of the leading magnetic metal thin film 51 to the film thickness H of the trailing metal magnetic thin film 52 is H because the total film thickness is 15 μm.
/ W = 10/5 = 2. Therefore, it is necessary to satisfy H / W> 2 in order to keep the image quality at a level that does not deteriorate due to uneven wear. On the other hand, the upper limit is determined in a range where film peeling does not occur because film peeling occurs when the film thickness is too large. For example, the upper limit is H / W ≦ 10
Is. It should be noted that although the saturation characteristic of the metal magnetic thin film 4 on the leading side is mainly important for the recording characteristics, it becomes easy to saturate when the film thickness of the metal magnetic thin film 4 on the leading side becomes thin, so the lower limit film thickness is set to about 2 μm. Is desirable. Also, regarding the upper limit, general metal in
In the gap type head, the thickness of the metal magnetic thin film is 4 to 1
Since it is about 0 μm, about 5 μm is preferable.

In the magnetic head constructed as described above, even if the sliding surface of the magnetic recording medium is abraded due to the sliding contact with the magnetic recording medium, uneven wear is small, and in particular, a step difference in the magnetic gap portion is generated. It is much smaller than a head with the same film thickness. Therefore, spacing loss is reduced and head output is improved.

[0021]

As is apparent from the above description, in the magnetic head of the present invention, the thickness of the metal magnetic thin film on the leading side is smaller than that of the metal magnetic thin film on the trailing side. Therefore, the step difference in the magnetic gap portion due to the uneven wear can be reduced. Therefore, even when used in a dusty place, the spacing loss due to the step in the magnetic gap can be reduced, and the head output can be improved and the image quality can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a magnetic head to which the present invention is applied.

FIG. 2 is an enlarged side view of a magnetic gap portion of a magnetic head to which the present invention is applied.

FIG. 3 is a diagram showing a state of a sliding surface side when a metal-in-gap type magnetic head is mounted on a video tape recorder outdoors in a dusty atmosphere and a tape running test is performed.

FIG. 4 is a characteristic diagram showing a change in separation loss when the magnetic gap position is moved to the leading side.

[Explanation of symbols]

 1, 2 ... Auxiliary core part (ferrite) 3, 4 ... Metal magnetic thin film 7 ... Gap film

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Kaoru Aoki 6-5-6 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Magne Products Co., Ltd. (72) Yukari Utsumi 6-chome, Kita-Shinagawa, Shinagawa-ku, Tokyo No. 5 and 6 in Sony Magne Products Co., Ltd.

Claims (1)

[Claims] 1. A magnetic head comprising a pair of magnetic core halves composed of an oxide magnetic material and a metal magnetic thin film, the metal magnetic thin films being abutted against each other to form a magnetic gap. The ratio of the film thickness W of the metal magnetic thin film arranged on the inlet side to the film thickness H of the metal magnetic thin film arranged on the outlet side with respect to the traveling direction of the medium is 2 <H / W ≦ 10. Magnetic head.