Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2001-03-20
2004-04-13
Watko, Julie Anne (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06721132
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an inductive head for use in magnetic recording.
2. Description of the Related Art
With increasing recording density of magnetic disk apparatuses, magnetic recording media enhance the coercivity, and the track width of inductive heads for use in recording is made smaller. In addition, as the coercivity of the magnetic recording media is made higher, the thickness of the inductive heads is increased in order to provide a magnetic flux enough for recording. At present, the thickness of the front end of an upper magnetic core of the inductive heads is increased as compared with the track width, thereby making it more difficult to manufacture them.
In order to solve the problems, Japanese Un-examined Patent Publication No. Hei 7(95)-296328 describes the structure of an inductive head having a trench with a smaller width than the width of the magnetic pole end of the upper magnetic core of the inductive head, and the width of the trench is defining a track width.
As described above, in the inductive head described in Japanese Un-examined Patent Publication No. Hei 7(95)-296328, the width of the magnetic pole end of the upper magnetic core is larger than the magnetic pole tip layer defining the track width. This structure can maintain the large magnetic flux on the front end of the upper magnetic core, so as to manufacture a magnetic pole tip layer having a small thickness and a track width with high precision. However, a large magnetic field is leaked not only from the magnetic gap portion but also from the front end portion of the upper magnetic core. At recording, the recording magnetic field is applied to the recording media in a region wider than a track width desired, thereby damaging adjacent information.
As one of means of solving the problem, in order to reduce the magnetic field leaked from the magnetic pole end portion of the upper magnetic core, the upper magnetic core is constructed such that the magnetic pole end surface thereof is recessed from the air bearing surface. However, in this case, as the magnetic field leaked is reduced, the recording magnetic field is small.
SUMMARY OF THE INVENTION
In order to realize a small track width, an inductive head according to the present invention forms a magnetic pole tip layer having a substantially track width at least near the air bearing surface between an upper magnetic core and a lower magnetic core.
In order to efficiently carry the magnetic flux to the magnetic pole tip layer, the top surface of the rear end of the magnetic pole tip layer is milled, and then the rear end of the magnetic pole tip layer is connected to the front end of the upper magnetic core having a width larger than that of the rear end of the magnetic pole tip layer, so as to realize a recording head having a large recording magnetic field.
When the front end of the upper magnetic core is exposed from the air bearing surface of the magnetic head, the magnetic field leaked from the both side of front end of the upper magnetic core can damage information of the adjacent track. In order to avoid this, in the recording head of the present invention, the front end of the upper magnetic core is desirably recessed from the air bearing surface by 0.2 to 3.0 &mgr;m.
REFERENCES:
patent: 5245493 (1993-09-01), Kawabe et al.
patent: 5617278 (1997-04-01), Cheng et al.
patent: 5652687 (1997-07-01), Chen et al.
patent: 5828533 (1998-10-01), Ohashi et al.
patent: 6151193 (2000-11-01), Terunuma et al.
patent: 2002/0048117 (2002-04-01), Ostrowski et al.
patent: 2002/0060878 (2002-05-01), Kamijima
patent: 7-296328 (1995-11-01), None
Micropatent PatSearch—Abstract of JP07296328.
S. Narumi et al., “Simulation of the write field for T-shaped pole heads”,Journal of Applied Physics, vol. 87, No. 9, Parts 2 and 3, 1 May 2000, pp. 5419-5421.
Hoshiya Hiroyuki
Maruyama Yohji
Narumi Shun-ichi
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