Dynamic magnetic information storage or retrieval – Head – Core
Patent
1993-05-25
1995-04-04
Sniezek, Andrew L.
Dynamic magnetic information storage or retrieval
Head
Core
360119, 360122, G11B 5147
Patent
active
054042607
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns a magnetic recording/playback head and, more particularly, a plane head, namely a magnetic head wherein the magnetic poles are located along one and the same plane. A magnetic head of this type can be used particularly in techniques for recording/playback on magnetic tapes. The invention also concerns a method for making a magnetic head of this type.
2. Discussion of the Background
The making of plane magnetic heads, of the shape shown in FIG. 1, is known.
These heads possess a magnetic circuit M having a plane face P. The magnetic poles of the recording head and the gap that separates them are located along this plane P. The recording medium such as a magnetic tape is placed, in the vicinity of the magnetic poles and of the gap E, parallel to the plane P. A magnetic field induction coil, supplied with current through the connections 70 and 71, surround an arm of the magnetic circuit M. As can be seen in FIG. 1, a head of this type has a narrowed portion at the gap E. This narrowed portion is brittle and difficult to make.
The invention concerns a head of this type which is less brittle and easier to make.
Furthermore, in known plane heads, the size of the gap (thickness of 0.2 micrometers and height of one micrometer) necessitates achieving growths of non-plane materials as described, for example, in the French patent application No. 86 14974, filed on 28th Oct., 1986. Thus, as shown in FIG. 2, a magnetic pole P1 is made on a substrate S with a layer of non-magnetic material E placed on a flank of the pole P1. Another layer of magnetic material (P2) is deposited on the unit. Then the upper face of the head is machined to obtain a plane magnetic head as shown in FIG. 3, with the magnetic poles P1 and P2 separated by a gap E.
As can be seen in FIG. 2, the layer of magnetic material forming the magnetic pole P2 must match the shape of the gap E: this disturbs the magnetic properties at the edge of the gap E. The definition of the gap and the discontinuity that it creates in the magnetic field thus get deteriorated, and this happens in a zone extending to a distance equal to some multiples of the height of the gap, measured from the gap.
However, it is essential to make thin layers of a thickness of 2 to 3 micrometers for plane magnetic heads. According to this technique, the magnetic pole P2 is thus dependent on the height of the gap.
The invention provides, according to one variant embodiment, for resolving this difficulty.
SUMMARY OF THE INVENTION
The invention thus concerns a magnetic head comprising a magnetic circuit of massive form comprising a plane face corresponding to the recording face of the head, characterized in that this magnetic circuit comprises: plane face, said interruption comprising a non-magnetic material which is flush with the plane face of the magnetic circuit; deposited on said plane face and separated by a gap located at the non-magnetic material.
The invention also concerns a magnetic head characterized in that the magnetic circuit has two U-shaped parts bonded to each other by the ends, one of the ends of at least one of these two parts comprising a part made of non-magnetic material which is flush with said plane face, the two layers made of magnetic material being made on said plane face with the gap located at the part made of non-magnetic material.
Finally, the invention concerns a method for fabricating a magnetic head, characterized in that it comprises the following steps: one plane face and, incorporated in this part, an element made of non-magnetic material flush with the plane face on a determined surface; reaching the element made of non-magnetic material in such a way that this element forms an interruption in the magnetic circuit formed by said part; two edges separated by a gap located on said determined surface occupied by the element made of non-magnetic material, these magnetic poles being made by means of a thin layer of magnetic material; the aperture and surrounding the ma
REFERENCES:
patent: 3845503 (1974-10-01), Kanai
patent: 3893187 (1975-07-01), Kanai et al.
patent: 4100584 (1978-07-01), Behr
patent: 4670972 (1987-06-01), Sakakima
Patent Abstracts of Japan, vol. 8, No.: 97 (P-272) (15934) May 8, 1984, & JP,A598115 (Matsushta Denki Sangyo K.K.) Jan. 17, 1984.
Proceedings of the IEEE, vol. 74, No.: 11, Nov. 1986, IEEE, (New York, U.S.) F. Jeffers: "High-Density Magnetic Recording Heads", pp. 1540-1556.
Machui Jurgen
Meunier Paul L.
"Thomson-CSF"
Sniezek Andrew L.
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