Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2002-06-03
2004-01-20
Miller, Brian E. (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S236100, C360S097010
Reexamination Certificate
active
06680820
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a magnetic disk drive, particularly to a magnetic disk drive wherein, with respect to outer dimensions of a slider of a magnetic head included as part of the magnetic disk drive along with a magnetic disk and a head supporting device, a thickness from a flying plane to an opposite surface on the reverse side thereof is determined to be 0.65 mm or less, a length thereof in the direction of air discharge to be 3 mm or less, or preferably 0.5 to 3 mm and a width in a direction orthogonal to the direction of air discharge to be 2.5 mm or less, or preferably 0.5 to 2.5 mm. Therefore, it is possible to achieve miniaturization, a high capacity and a high density for the magnetic recording medium, and a smaller diameter of the magnetic disk with high durability and high stability thereof.
2. Discussion of the Background
In a conventional magnetic disk drive, a magnetic head is used which flies by dynamic pressure caused by running a magnetic disk opposed thereto and maintaining head clearance due to a minute air bearing generated between the magnetic disk and the magnetic head. A flying-type magnetic head has a basic structure including reading/writing elements formed on a slider having flying planes on the side of a surface thereof opposing a magnetic disk. As conventional examples, a Winchester-type magnetic head provided with a U-shaped core having a coil at a slider composed of a magnetic body and a composite-type magnetic head attached with a bulk-type reading/writing element in a groove of a slider composed of a nonmagnetic ceramic structure and a thin film magnetic head formed with thin film reading/writing elements on a slider thereof by a process similar to the semiconductor production technology, are well known.
Among these flying-type magnetic heads, the Winchester-type magnetic head and the composite-type magnetic head are publicly known, for instance, by Japanese Examined Patent Publication No. 569/1982 (U.S. Pat. No. 3,823,416), Japanese Examined Patent Publication No. 21329/1983, Japanese Examined Patent Publication No. 28650/1983 or the like. The reading/writing elements are the bulk-type ones provided with coils composed of wires wound around cores.
The thin film magnetic head is publicly known, for instance, by Japanese Examined Patent Publication No. 84019/1980 (U.S. Pat. No. 4,190,872), Japanese Unexamined Patent Publication No. 84020/1980 (U.S. Pat. No. 4,219,854) or the like. The thin film magnetic head is provided with a structure wherein a thin film magnetic film, a conductive coil film, an inter-coil-layer insulating film, a protection film and the like are formed on a slider. With respect to the thin film magnetic head, the inductance value of the conductive coil film is low compared with a bulk-type flying magnetic head, by a single digit or more. Accordingly, the high frequency characteristic thereof is extremely good and the thin film magnetic head has excellent high response performance and is suitable for the high density recording. Owing to this characteristic, the thin film magnetic head can achieve a high speed in data transfer and a high density of magnetic recording in a domain which cannot be reached by the bulk-type flying magnetic head.
Furthermore, the thin film magnetic head is provided with characteristics wherein a magnetic film constructing a magnetic circuit thereof is composed of a metallic magnetic material of permalloy or the like having a high saturation magnetic flux density and a high permeability, a magnetic gap length thereof can be reduced, and a pole width for reading and writing that can be extremely narrowed down. Accordingly, in addition to the excellent high frequency characteristic wherein the inductance value of the conductive coil film and the magnetic film composing a core is low, the thin magnetic head can achieve an excellent high frequency response performance and high recording density compared with the bulk-type flying magnetic head.
Next, explanation will be given of a specific example of the flying-type magnetic head in reference to FIG.
20
.
FIG. 20
is a perspective view of a conventional magnetic head, wherein a reference numeral
1
designates a slider composed of, for instance, a ceramic structure, and
2
, a reading/writing element.
The slider
1
is formed to have two rails
101
and
102
spaced apart from each other on a plane thereof opposing a magnetic disk and the surfaces of the rails
101
and
102
are formed with flying planes
103
and
104
having a high flatness.
With respect to the outer dimension of the slider
1
, as shown for instance in U.S. Pat. No. 4,624,048, normally, a thickness d from each of the flying planes
103
and
104
to an opposite surface on the reverse side
105
is selected to be 0.85 mm, a length L in the air discharge direction is selected to be 4 mm and a width w in a direction orthogonal to the air discharge direction is selected to be 3.2 mm. The flying planes
103
and
104
are provided with structures wherein tapered portions
103
a
and
104
a
each is provided on the side of an end thereof which makes an inflow end for an air flow that flows in the direction of an arrow mark “a,” generated in the combination thereof with a magnetic disk.
The reading/writing element
2
is a thin film element formed by a process similar to the IC production technology in case of a thin film magnetic head, which is attached to an end portion of the air discharge on the opposite side of the tapered portions
103
a
and
104
a
. Although not illustrated, the Winchester-type magnetic head, or the composite-type magnetic head is a bulk-type one provided with a coil wound around a core.
When the reading/writing element
2
is composed of a thin film element, with respect to the dimension of the reading/writing element
2
, to satisfy a required electromagnetic conversion performance, a diameter D
2
thereof in a direction orthogonal to the air discharge direction is determined to be approximately 0.3 mm, and a diameter thereof D
1
in a direction from the flying planes
103
and
104
to the opposite surface
105
, approximately 0.4 mm. Furthermore, the thin film magnetic head is provided with take-out electrodes
201
and
202
on a side end face of the slider
1
attached with the reading/writing elements. These take-out electrodes
201
and
202
communicate to a conductive coil film of the reading/writing element
2
, not shown. The take-out electrodes
201
and
202
are portions to which lead wires communicating to the magnetic disk drive are connected. To provide a lead wire connecting area, a length L
0
thereof in a direction orthogonal to the air discharge direction “a” is determined to be about 0.5 mm, and a wire width h
1
viewed in the direction of the opposite surface
105
to the flying planes
103
and
104
, approximately 0.2 mm.
The above thin film magnetic head is produced utilizing a high accuracy pattern forming technology, such as photolithography, by forming a great number of thin film reading/writing elements on a wafer to be transformed into a portion of the slider
1
, by separating the thin film reading/writing elements obtained by performing a cutting operation on the wafer, and by performing a necessary grooving operation on the rails
101
and
102
or the like and polishing the flying planes
103
and
104
.
The magnetic disk drive is attached with the above magnetic head on a front end portion of a head supporting device an end of which is supported by a positioning device that positions the magnetic head on predetermined tracks of the magnetic disk and drives the magnetic head by a so-called contact-start-stop (hereinafter CSS) system wherein the flying planes
103
and
104
of the slider
1
contact the surface of the magnetic disk by a spring and starting and stopping thereof are performed in the contact state. Thus, when the magnetic disk is stationary, the flying planes
103
and
104
are pressed to the surface of the magnetic disk by spring pressure. When the magnetic
Fukuda Kazumasa
Matsuzaki Mikio
Tsuna Takamitsu
Miller Brian E.
TDK Corporation
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