Dynamic magnetic information storage or retrieval – Head – Head surface structure
Patent
1989-06-27
1991-09-17
Tupper, Robert S.
Dynamic magnetic information storage or retrieval
Head
Head surface structure
360126, G11B 5193, G11B 531
Patent
active
050500279
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns a magnetic recording-playback head with abrasion-resisting layer and, more particularly, a magnetic head comprising, on its surface in contact with the magnetic recording medium, a wear-resisting layer. The invention also concerns a method for making an abrasion-resistant layer of this type.
2. Discussion of Background
Magnetic heads made with a ferrite substrate such as very high-definition heads for present-day video (VHS) applications, subjected to tape running at 5 ms.sup.-1 or present-day digital heads (3.32 ms.sup.-1) known as rotary digital audio tapes (RDAT) undergo slow erosion which makes them unusable at the end of 2000 hours of use. Throughout a working time such as this, the head may be worn out on a height of 20 micrometers.
One solution to the problem of wear is to deposit an abrasion-resisting layer on the head. Unfortunately, it is very difficult to make materials like carbon cling to ferrite, and, given the heterogeneity of the materials that might form a magnetic head, such as ferrite, alumina, glass, the carbon layer may prove to be difficult to deposit.
SUMMARY OF THE INVENTION
The invention enables the resolving of this problem of the deposition of an abrasion-resisting layer on a magnetic head and, notably, on the surface of the head in contact with a magnetic recording medium.
The invention therefore concerns a magnetic recording/playback head comprising two magnetic poles separated by a gap made of non-magnetic material, characterized in that it also comprises: coefficient of bonding on the magnetic poles, and on which a carbon-based layer has a high bonding coefficent; abrasion-resisting layer of a carbon-based material.
The invention also concerns a method for the fabrication of a magnetic recording/playback head according to any one of the preceding claims, characterized in that it comprises the following steps: poles of the magnetic head, of a first clinging layer; on the second magnetic pole, of a layer of a non-magnetic material; second clinging layer; layer of non-magnetic material until the first clinging layer is reached; the layer of non-magnetic material remaining between the two clinging layers, of a layer of abrasion-resisting material until the first clinging layer is reached.
BRIEF DESCRIPTION OF THE DRAWINGS
The different objects and characteristics of the invention will appear more clearly through the following description in referring to to the appended figures, which represent:
FIG. 1, an embodiment of a magnetic head according to the invention;
FIG. 2, a variant of the magnetic head of FIG. 1;
FIG. 3, a planar magnetic head according to the invention in a top view;
FIG. 4, a sectional view of a magnetic head in thin layers;
FIGS. 5 to 7, different steps of a fabrication method according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, we shall first describe an embodiment of a magnetic head according to the invention.
This magnetic head has two magnetic poles P1 and P2, made of ferrite-based magnetic material. The two magnetic poles P1, P2, are separated by a gap E1, made of alumina (Al.sub.2 A.sub.3) based or silica (SiO.sub.2) based non-magnetic material.
A magnetic head of this type has to be covered with a layer of hard material, resistant to abrasion. A layer of this type may preferably be a carbon-based compound. However, it turns out that carbon clings poorly to ferrite.
According to the invention, as shown in FIG. 1, there is provision, on each magnetic pole, P1, P2, for a clinging layer S1, S2, made of magnetic material.
The material forming the layers S1, S2 has a composition such that it clings well to the ferrite of the magnetic poles S1, S2 and that the abrasion-resisting layer C1 also clings well to this material.
On the layers S1, S2, there is deposited an abrasion resistant layer C1, such as a carbon-based layer.
The invention provides, and this is important, for the layers S1, S2, to be made of magnetic material
REFERENCES:
patent: 4644431 (1987-02-01), Kishine et al.
patent: 4849842 (1989-07-01), Meunier et al.
Patent Abstracts of Japan, vol. 10, No. 180 (P-471) (2236), Jul. 24, 1986.
Patent Abstracts of Japan, vol. 10, No. 45 (P-430) (2102), Feb. 21, 1986.
Lehureau Jean C.
Meunier Paul L.
Rolland Jean L.
"Thomson-CSF"
Tupper Robert S.
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