Stock material or miscellaneous articles – Circular sheet or circular blank – Recording medium or carrier
Reexamination Certificate
2001-02-13
2003-09-16
Resan, Stevan A. (Department: 1773)
Stock material or miscellaneous articles
Circular sheet or circular blank
Recording medium or carrier
C428S690000, C428S690000, C428S690000, C360S031000
Reexamination Certificate
active
06620481
ABSTRACT:
BACKGROUND OF THE INVENTION
i) Field of the Invention
The present invention relates to a magnetic recording medium in which information is magnetically recorded, a method of manufacturing the magnetic recording medium, and an information regeneration apparatus for regenerating the information recorded in the magnetic recording medium.
ii) Description of Related Art
In recent years, with spread of computers, a large amount of information has been handled in a daily manner, and as one of apparatuses for recording/regenerating a large amount of information, a hard disk drive (HDD) has been used.
The HDD incorporates a magnetic disk as a disk-like magnetic recording medium in which the information is recorded, and a magnetic head for recording/regenerating the information in the magnetic disk.
FIG. 1
is a diagram showing a positional relation between the magnetic recording medium and the magnetic head in the HDD.
FIG. 1
shows a magnetic disk
20
, and a head slider
30
floated from the magnetic disk
20
and provided with a magnetic head
31
in the vicinity of an end thereof.
In the magnetic disk
20
, an underlayer
12
constituted of Cr, and the like is formed on a nonmagnetic substrate
11
, and a magnetic layer
13
of a material indicating ferromagnetism is formed on the underlayer
12
. The magnetic layer
13
is divided into a plurality of micro areas, and carries information in accordance with magnetization directions in the respective micro areas. Moreover, the magnetic layer
13
is covered and protected by a protective layer
14
formed of carbon and the like and a lubricating layer
15
of perfluoropolyether (PFPE) and the like. During operation of HDD, the magnetic disk
20
is in a rotating state.
For the head slider
30
, a floating surface facing the magnetic disk
20
is covered and protected by a protective film
32
, for example, of carbon. The head slider
30
and the magnetic head
31
included in the head slider
30
are disposed in the vicinity of the magnetic disk
20
, and during starting/stopping of rotation of the magnetic disk, the floating surface contacts the surface of the magnetic disk
20
to slide thereon, but during operation, as shown in
FIG. 1
, a floating state above the rotating magnetic disk
20
is obtained.
The magnetic head
31
generates a magnetic field in accordance with a signal current from the outside, appropriately reverses each magnetization of each micro area of the magnetic disk to record information, and reads the respective magnetization directions of the magnetic disk
20
to regenerate the information.
A recording density of the information recorded in the magnetic disk is enhanced every year, and a magnetic disk in which recording with a higher recording density is possible has been demanded. As one factor necessary for enhancing the recording density, as shown by an arrow in
FIG. 1
, a distance (magnetic spacing) between the magnetic layer
13
of the magnetic disk and the magnetic head
31
is reduced. In recent years, the magnetic spacing of about 50 nm has been realized, but in order to enhance the recording density, the magnetic spacing needs to further be reduced.
The reduction of the magnetic spacing is realized, for example, by thinning the protective layer
14
. In recent years, in order to reduce the magnetic spacing, the protective layer of the magnetic disk is formed with a very thin film having thickness of about a dozen or so nanometers over the entire surface of the disk, but to further reduce the magnetic spacing, it has been requested to set the thickness of the protective layer to 10 nm or less.
However, when the protective layer with a thickness of 10 nm or less is formed, for example, using an amorphous carbon based material by a sputtering process, the formed protective layer is insufficient in film hardness and surface coverage, cannot maintain stable friction/abrasion properties for a long period and is disadvantageously inferior in contact sliding durability. Moreover, in a case in which the protective layer with a thickness of 10 nm or less is formed using the amorphous carbon based material by a plasma CVD process which is known to form the film with higher hardness and higher coverage rate than those of the sputtering process, in a thin film area of several nanometers, in spite of the high hardness of the protective layer itself, the hardness of the underlying magnetic layer influences a surface hardness, as a result the hardness of the medium surface is reduced, and there still occurs a problem that the contact sliding durability is deteriorated.
SUMMARY OF THE INVENTION
The present invention has been developed in consideration of the aforementioned circumstances, and an object thereof is to provide a magnetic recording medium in which reduction of a magnetic spacing and securing of a contact sliding durability are compatible with each other, a magnetic recording medium manufacture method, and an information regeneration apparatus.
To achieve the aforementioned object according to the present invention there is provided a first magnetic recording medium comprising:
a disk-like substrate;
a magnetic layer consisting of a material indicating ferromagnetism, said magnetic layer being formed on said substrate; and
a protective layer for protecting the magnetic layer, said protective layer being formed in at least one area of an outer peripheral area and an inner peripheral area of a disk excluding a middle area held between the outer peripheral area and the inner peripheral area on said magnetic layer.
The first magnetic recording medium of the present invention is employed, for example, in HDD, the protective layer is disposed only in areas such as the outer peripheral area or inner peripheral area which is brought into contact with a magnetic head in the HDD in a CSS or Load/Unload state, and the protective layer can be provided with a film thickness equal to a conventional film thickness as occasion demands. Therefore, in the first magnetic recording medium of the present invention, contact sliding durability is secured against the magnetic head. Moreover, for the first magnetic recording medium of the present invention, since no protective layer is formed in the middle area or another area with information recorded therein, the magnetic spacing can be reduced by the area with no protective layer formed therein. As described above, in the first magnetic recording medium of the present invention, the reduced magnetic spacing and the contact sliding durability are compatible with each other.
To achieve the aforementioned object according to the present invention there is provided a second magnetic recording medium comprising:
a disk-like substrate;
a magnetic layer consisting of a material indicating ferromagnetism, wherein a surface layer portion is modified by introducing a predetermined element, said magnetic layer being formed on said substrate; and
a protective layer for protecting the magnetic layer, said protective layer being formed in at least one area of an outer peripheral area and an inner peripheral area of a disk excluding a middle area held between the outer peripheral area and the inner peripheral area on the modified surface layer portion of said magnetic layer.
Similarly as the first magnetic recording medium of the present invention, the second magnetic recording medium of the present invention is employed, for example, in the HDD, the protective layer is disposed only in the areas such as the outer peripheral area or inner peripheral area which is brought into contact with the magnetic head in the HDD in the CSS or Load/Unload state, and the protective layer can be provided with the film thickness equal to the conventional film thickness as occasion demands. Therefore, in the second magnetic recording medium of the present invention, the contact sliding durability is secured against the magnetic head. Moreover, for the second magnetic recording medium of the present invention, no protective layer is formed in the middle area or another area with information recorded therei
Fujitsu Limited
Greer Burns & Crain Ltd.
Resan Stevan A.
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