Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2002-12-30
2004-09-21
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S235800, C360S236300, C360S235100
Reexamination Certificate
active
06795275
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a magnetic disk device, particularly to the structure of a magnetic head slider and a magnetic disk in a contact recording magnetic disk device in which the magnetic head slider touches the magnetic disk.
To increase the recording density of the magnetic disk device, the narrowing of flying height, that is defined as the spacing between a magnetic head slider mounted with a magnetic head and a rotating magnetic disk, is important.
The uniform flying height over the all surface of the magnetic disk is also required. Further, the fluctuation of flying height by an environmental variation, especially the decrease of flying height by the drop of atmospheric pressure in the high altitude is required to be minimized.
In proportion to the decrease of the flying height, the possibility of the contact of the magnetic head slider with the magnetic disk increases, and if the contacting state is severe, the magnetic head slider crashes against the magnetic disk and there is the possibility of destroying the recorded data on the magnetic disk.
As a conventional technology for generally equalizing the flying height over the all surface of the magnetic disk, reducing the decrease of flying height and keeping the uniform flying height all over the magnetic disk in the high altitude, a technology is disclosed by JP-A-2000-57724.
Said Japanese publication discloses a step air bearing sub-ambient pressure force magnetic head slider which generally equalizes the flying height over the all surface of the magnetic disk and enabling to reduce the decrease of the flying height in the high altitude by the adequate combination of a step air bearing having the recess of the depth of sub-microns, the recess deeper than that of the air bearing for generating sub-ambient pressure force and the rail surfaces.
SUMMARY OF THE INVENTION
A first thing to do to increase the recording density of magnetic disk device while keeping the high reliability of it is to devise the measures of preventing the contact between the magnetic head slider and the magnetic disk by narrowing and equalizing the flying height over the all surface of the magnetic disk, reducing the fluctuation of the flying height caused by the variation of the manufacturing of the magnetic head slider, reducing the fluctuation of flying height by seek operations, and reducing the decrease of flying height in the high altitude.
However, whatever measures are taken with above described effects, the contact between the magnetic head slider and the magnetic disk is unavoidable with the narrow flying height of 15 nm or less and the vibration or the wear of the magnetic head slider are becoming a new problem.
Regarding to the step air bearing sub-ambient pressure force magnetic head slider disclosed by said JP-A-2000-57724, it is disclosed that the flying height is generally uniform, and the fluctuations of the flying height by the variation of the manufacturing, seek operations and in the high altitude can be reduced.
However, it gives no considerations especially to the vibration of magnetic head slider caused by the contact with the magnetic disk and improvement on this point has been requested.
Further, to reduce fluctuations in the flying height due to variations in manufacturing, it is necessary for manufacturing at high accuracy even when the depth is reduced by the formation of a surface such as a slider rail surface. For example, in a case when the depth of 400 nm is fabricated at ±10% accuracy, a tolerable variation is ±40 nm, whereas this is ±1 nm for the depth of 10 nm. A depth of 10 nm or less cannot be fabricated at an accuracy of about ±1 nm by the existent fabrication such as ion milling and an improvement has been demanded in this regard.
The present invention relates to the above described needs and intends to provide the magnetic disk device and the magnetic head slider that are generally uniform with the flying height over the all surface of the magnetic disk, reduced with the fluctuations of flying height by the variation of the manufacturing, seek operations and in the high altitude, and in case of the contact between the magnetic head slider and the magnetic disk, the magnetic head slider slides on the surface of the magnetic disk smoothly maintaining a high reliability.
Further, the present invention intends to provide a magnetic head slider with less variation in the depth even in a case where the depth is reduced as shallow as 10 nm or less due to the formation of a surface such as a slider rail surface.
To solve above described problems, the present invention adopts the following constitution.
A magnetic head slider comprising a magnetic head mounting surface on the air flow-out side which is the closest to the magnetic disk in operation and mounted with the magnetic head, a slider rail surface which is separated from said magnetic head mounting surface and formed with the surface near to air flow-in side and both side surfaces near the air flow-in edge having the depth of 10 nm to 50 nm from the magnetic head mounted surface, a slider step air bearing surface formed surrounding said slider rail surface and has the depth of 50 nm to 200 nm from said slider rail surface, and a recess for generating sub-ambient pressure force surrounding said slider step air bearing surface and having the depth of 400 nm to 1.3 &mgr;m from said slider step air bearing surface.
Further, the present invention intends to provide a magnetic head slider comprising a magnetic head mounting surface on the air flow-out side which is closest to the magnetic disk in operation and provided with the magnetic head, a protective film of 10 nm or less comprising one or more layers of films at least formed on the magnetic head mounting surface, a slider rail surface formed with the surface near to air flow-in side and the surface near to air flow-out side, a step air bearing surface having a depth of about 50 nm to 200 nm from the surface of the slider rail surface at least on the air flow-in side, and a recess for generating sub-ambient pressure force surrounding the slider step air bearing surface and having a depth of 400 nm to 1.3 &mgr;m, in which the surface near the air flow-out side surface in the slider rail has a depth equal to a thickness of one or more layers of the protective film from the surface of the protective film comprising one or more layers of films.
A magnetic disk device is provided with the magnetic head slider mounted with the magnetic head and the magnetic disk that is a data recording medium, wherein the vicinity of said magnetic head of said magnetic head slider has the possibility of contacting said magnetic disk, said magnetic head slider has the length of 1.25 mm or less, the width of 1 mm or less and the thickness of 0.3 mm or less, and the friction force exerted between said magnetic head slider and said magnetic disk is 10 mN or less.
A magnetic disk device is provided with the magnetic head slider having the magnetic head and the magnetic disk that is the data recording medium, wherein the vicinity of said magnetic head of said magnetic head slider has the possibility of contacting said magnetic disk, the floating pitch angle of said magnetic head slider is 50 micro-radian or more, the mean surface roughness Ra of said magnetic disk is 2 nm or less and the peak count of it is 700/400 &mgr;m2 or more.
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Anan Hidetoshi
Hashimoto Kiyoshi
Higashiya Teruyoshi
Kohira Hidekazu
Matsuda Akira
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Tupper Robert S.
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