JPH065568B2 - Magnetic head - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic transducer for magnetic recording / reproducing, that is, a magnetic head, and more particularly to a thin film type video head for a VTR for wideband recording / reproducing.

[Conventional technology]

Conventionally, a ferromagnetic alloy multi-layer thin film head has a non-magnetic metal or ceramic substrate whose coefficient of thermal expansion is almost the same as that of the ferromagnetic alloy, and the ferromagnetic alloy thin film and the electrically insulating film are alternately sputtered or evaporated. It was attached by means to form a multilayer film, which was used as the core material.
Further, the same type of substrate is used as a backing plate to have a sandwich structure. These ferromagnetic alloy multilayer thin film heads are described in the following documents, for example. Shibatani et al. "Fabrication of magnetic alloy film by sputtering and its application to narrow track video head" IEICE Transactions 57C-9 [p325]
(Sho 49), Kawano et al. "Sendust video head for metal tape" Proceedings of the National Conference of the Television Society of Japan 8-3 [p197]
(Showa 56), Kuroe et al., "Sputter Amorphous Video Head," Proceedings of the IEICE General Conference 239 [p1-241] (Show 5
9), Saito et al. "Fe-Al-Si Alloy Sputtered Film Video Head" Proceedings of the Japan Society for Applied Magnetics Academic Conference 29PA-2 [p288]
(Sho 60).

In such a structure of the magnetic head, the core main magnetic path is composed of only the ferromagnetic alloy multilayer thin film, and the cross-sectional width thereof is the same as the film thickness, which is extremely narrow. Further, in terms of production technology, if a deviation occurs in the step of abutting the rear gap portion, it becomes narrower and intermittent, and the magnetic flux transmission efficiency decreases. Fig. 4 shows the situation. In the figure, 1
Is a substrate, 1'is a contact substrate, 2 is a ferromagnetic alloy multilayer film portion, 3
Is the back gap. Since the substrate 1 and the backing substrate 1'are non-magnetic materials, if the film shifts in the rear gap portion, the magnetic flux transmission efficiency is reduced accordingly.

Since the ferromagnetic alloy multilayer thin film and the two substrates are made of different materials, when they slide on the magnetic tape, uneven wear (step difference due to difference in wear) occurs due to difference in wear characteristics. Substrate 1,1 '
Since a high hardness wear-resistant material is used for the ferromagnetic alloy multilayer thin film 2 forming the main magnetic path as shown in FIG.
2A is generated, the space between the magnetic tape 4 and the magnetic tape 4 increases, and the space loss increases. At the same time, the contact becomes unstable.

Further, since the ferromagnetic alloy multilayer thin film and the thin film deposition substrate are different materials, strictly speaking, the physical properties such as the coefficient of thermal expansion do not match, and the adhesion strength during the processes such as sputtering and vapor deposition is weak. Further, mechanical processing, gap forming welding, heat treatment, or handling during the head manufacturing process often causes damages such as cracks and chips in the thin film, which may cause the thin film to be lost or dropped.

There was a problem in terms of performance and production technology.

[Problems to be solved by the invention]

The present invention has the above-mentioned conventional drawbacks, that is, a decrease in magnetic flux transmission efficiency due to a shift in the rear gap portion, an increase in space loss due to uneven wear of the head, unstable contact, and weak adhesion strength of the ferromagnetic alloy multilayer film to the substrate. It is an object of the present invention to provide a magnetic head having improved recording / reproducing characteristics, particularly sensitivity, and excellent productivity.

[Means for solving problems]

In order to achieve such an object, the magnetic head of the present invention is a magnetic head using a ferromagnetic alloy multilayer thin film as a core material, and the substrate is a ferromagnetic alloy base material for preparing a ferromagnetic alloy multilayer thin film or a ferromagnetic alloy base material. It is characterized by being formed of a ferromagnetic alloy having the same or substantially the same wear characteristics and thermal expansion coefficient as the material.

[Work]

According to the present invention, the core main magnetic path is composed of the ferromagnetic alloy multilayer thin film and the ferromagnetic alloy used as the substrate thereof, so that the cross-sectional width can be increased. Further, even if there is a deviation in the abutting process of the rear gap portion, the main magnetic path width is wide, so that the magnetic flux transmission efficiency does not decrease because the main magnetic path width is not intermittent. Further, since the ferromagnetic alloy multilayer thin film and both substrates are made of the same or similar material, when they slide on the magnetic tape, they have the same wear characteristics and do not cause uneven wear. Therefore, the ferromagnetic alloy multi-layered thin film does not have any dents and operates in a state where there is no space loss, that is, the contact between the head and tape is good. Furthermore, the physical properties such as the coefficient of thermal expansion are almost the same, and the adhesion strength in the processes such as sputtering and vapor deposition is strong. Therefore, it is less likely to be damaged during the head manufacturing process.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

A perspective view of the first embodiment is shown in FIG. The ferromagnetic alloy multilayer thin film deposition substrate 11 and the backing substrate 11 'for forming a sandwich structure are attached to the substrate 11 by sputtering, vapor deposition or the like to form the base material of the ferromagnetic alloy multilayer thin film 12 that constitutes the core main magnetic path ( The same material), or a similar ferromagnetic alloy having a similar composition and a similar thermal expansion coefficient and wear characteristics, and has a gap 13, a winding window 14 and a core 15 similar to a normal magnetic head. The structure is such that windings 16 are provided on both sides. In this case, the track width t is a dimension obtained by adding the film thickness of the ferromagnetic alloy multilayer thin film 12 and the thicknesses of both substrates 11 and 11 '. Such a magnetic head core has a thickness of, for example, 50 μm.
The sendust plate or sendust quenched ribbon that has been cut and polished as the substrate 11 is sputtered or vapor-deposited by alternately sending sendust having a thickness of 1 to 5 μm and sio ₂ having a thickness of about 0.2 μm on the substrate 11, and applying the same as the substrate 11. It is obtained by forming a sandwich structure with the substrate 11 '. The number of layers of the sendust multilayer film is determined according to the track width.
It is desirable that the alloy compositions of the substrate and the multilayer film are the same, but there is no problem even if they are slightly different. As the substrate and the multilayer magnetic alloy, for example, an amorphous Co-Zr-Nb alloy can be used.

FIG. 2 shows a perspective view of the second embodiment of the present invention, and FIG. 3 shows a top view thereof. This embodiment is a case of a high density recording head, in which only the vicinity of the gap of both substrates 11 and 11 'of the first embodiment is carved from both sides to form a concave portion 17 to narrow the track width t. The recess may be filled with glass or the like. The thinner the substrates 11, 11 'in the recess 17, the better.

Next, the operation of this head will be described. When a current is passed through the winding 16, a magnetic flux is generated in the core 15 and transmitted to the gap 13,
A leakage magnetic field is generated at this tip to magnetize (record) the medium. On the contrary, the leakage magnetic flux from the medium is collected in the gap 13 and transmitted by the core 15, and the winding 16 senses (reproduce) voltage.

〔The invention's effect〕

As described above, with the head configuration of the present invention, the core main magnetic path is composed of the ferromagnetic alloy multilayer thin film and the ferromagnetic alloy used as the substrate thereof, and its cross-sectional width can be increased. Further, even if there is a deviation in the abutting process of the rear gap portion, the main magnetic path width is wide, so that the magnetic flux transmission efficiency does not decrease because the main magnetic path width is not intermittent.

Since the ferromagnetic alloy multilayer thin film and both substrates are made of the same or similar material, when they slide on the magnetic tape, they have the same wear characteristics and do not cause uneven wear. Therefore, the ferromagnetic alloy multi-layered thin film does not have any dents and operates in a state where there is no space loss, that is, the contact between the head and tape is good.

Further, since the ferromagnetic alloy multilayer thin film and the ferromagnetic alloy multilayer thin film deposition substrate are the same or similar materials,
The physical properties such as the coefficient of thermal expansion are almost the same, and the adhesion strength is strong during the processes such as sputtering and vapor deposition. Therefore,
Less likely to be damaged during the head manufacturing process.

By eliminating the drawbacks of the conventional thin film type head in terms of performance and production technology as described above, it is possible to improve recording / reproducing characteristics, particularly sensitivity and productivity.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the laminated head of the present invention, and FIGS. 2 and 3 are perspective views and top views showing a second embodiment (for high density recording), respectively, and FIG. FIG. 4 is an explanatory diagram of an interrupted magnetic path due to a shift of a rear gap portion in a conventional laminated head. FIG. 5 is a cross-sectional view illustrating an increase in space loss due to uneven wear in a conventional laminated head. 1, 11 ... Substrate, 1 ', 11' ... Reliable substrate, 2, 12 ... Ferromagnetic alloy multilayer thin film, 3, 13 ... Gap, 14 ... Winding window, 15 ... Core, 16 ... Winding.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shirai Aoki 1-10-11 Kinuta, Setagaya-ku, Tokyo Inside the Broadcasting Technology Laboratory, Japan Broadcasting Corporation (72) Inventor Hiromichi Shibata 1-10 Kinuta, Setagaya-ku, Tokyo No. 11 Inside the Japan Broadcasting Corporation Broadcasting Technology Laboratory

Claims (1)

[Claims] 1. In a magnetic head using a ferromagnetic alloy multilayer thin film as a core material, the substrate has a ferromagnetic alloy base material for producing the ferromagnetic alloy multilayer thin film, or the same or substantially the same wear characteristics as the ferromagnetic alloy base material. A magnetic head formed of a ferromagnetic alloy having a coefficient of thermal expansion.