Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
1998-06-16
2001-06-26
Renner, Craig A. (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S097020
Reexamination Certificate
active
06252742
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a head slider which moves over a storage medium in an external storage device such as a magnetic disk drive or an optical disk drive. More particularly, this invention relates to a floating head slider having air bearing surfaces which are separated from the disk surface when the head is stationary, yet do not accumulate excessive dust, and can be cleaned in areas of the disk surface provided for cleaning purposes.
2. Description of the Related Art
In disk drives, a CSS (Contact Start and Stop) system is generally adopted for head sliders which float over a storage medium such as a disk in such disk drives. In the CSS system, the head slider is positioned at a CSS zone on part of the surface of the disk medium when the disk drive is stationary. When the disk medium rotates, the head slider floats (or flies) over the surface of the disk medium of the disk drive.
A head slider is generally equipped with reading and/or writing heads. Recent magneto-optical disk drives are also equipped with a magnetic head for application of magnetic fields on the disk in reading and/or writing. Furthermore, on a test basis, an optical head including an optical element such as an object lens or a light emitting element has been installed on a head slider in order to allow a source of light to impinge onto a disk medium.
Such a slider is supported by a suspension, and is moved over the surface of a disk medium by maneuvering the suspension radially across the disk. The head slider floats due to the effect of the air flow over the surface of the rotating disk medium, or a principle of an air bearing force created by the dynamic pressure mechanism on the surface of disk medium.
In recent disk drives, there has been a trend toward lowering the floating height of the floating head slider to accommodate the faster pace with which advances are being achieved in high storage densities, as well as miniaturization. However, lowering the floating height may lead to other problems. For example, reducing the floating height of the slider may increase the risk that the slider will come into contact with projections on the disk surface, causing damage to the contacting surfaces. Consequently, efforts have been made to reduce the roughness of the disk surface to prevent the disk from coming into contact with the head when the floating height of the slider is lowered. However, the less disk surface roughness there is, the greater the contact area of the CSS zone and the more easily the slider will stick to the disk through adsorption. If the adsorption force is large enough, the disk driving motor will bear a heavier load and the suspension supporting the head may be damaged.
To reduce the adsorption force, some ideas have been disclosed, e.g., Japanese Laid open patents Tokkai-sho 63-37874 and Tokkai-hei 8-212740, in which a pad (also referred to as a projection) is attached to the air bearing surface (also referred to as a floating surface or rail surface) of a head slider facing a disk surface, to reduce the contact areas between the slider and the disk medium.
FIGS.
1
(
a
) and
1
(
b
) show head sliders based on the previous technology, depicting the surface which faces the disk medium (floating surface) and the air inflow end, respectively. Slider rails
92
and
93
, and pads
94
a,
94
b,
94
c
and
94
d
attached to rail surfaces
92
b
and
93
b
are installed onto the surface facing the disk on head slider
90
.
FIGS.
1
(
c
) and
1
(
d
) depict the surface of the side and the surface facing the disk (floating surface), and present some problems with the prior technology. Since the pads
94
a,
94
b,
94
c
and
94
d
project from the rail surfaces, which are the air bearing surfaces, airborne dust G inside the disk system tends to accumulate in the peripheries of pads
94
a,
94
b,
94
c
and
94
d,
conveyed by the air flow R created by rotation of the medium. As the amount of accumulated dust increases, fluctuations in the floating condition may eventually develop, resulting in system problems such as faulty recording/playing responses and head failures. Thus, there is a need for such head sliders which do not accumulate dust in this manner. There is also a need for disk arrangements by which the rail surfaces can be cleaned in service.
OBJECTS OF THE INVENTION
Accordingly, one object of this invention is to provide new and improved head sliders for magnetic storage devices.
Another object is to provide new and improved head sliders which float over a rotating disk medium by way of air flow beneath rail surfaces on the bottom of the slider, which air flow does not suffer from excessive dust accumulation on the rail surfaces.
Still another object is to provide methods and apparatus for cleaning the air bearing surfaces of floating head sliders.
SUMMARY OF THE INVENTION
With this background in mind, the present invention is directed at the provision of an improved head slider, as well as a mechanism capable of enhancing the reliability and durability of a disk system through optimization of the surface configuration of the slider. Two or more slider rails are provided with air bearing rail surfaces projecting downwards from a base plate, and extending lengthwise on the base plate to generate a hovering force when the underlying disk rotates at sufficient speed. Two or more pads are attached to the base plate which project below the rail surfaces. In this manner, the pads do not interrupt the air flow over the air bearing rail surfaces, and let the dust pass through the air outlet ends of the rail surfaces, thereby minimizing the amount of dust that collects on the rail surfaces.
In one embodiment, the slider rails are installed on at least both sides of the base plate, and at least one of the pads is attached to either side of the base plate inside or outside of both slider rails. Consequently, it is possible to reduce dust accumulation on the rail surfaces. In addition, if two or more pads are attached to the areas outside the slider rails, the slider can be supported more steadily during CSS operations. This ensures that no base plate portion other than the pads comes into contact with the disk. Therefore, it is possible to reduce dust accumulation on the rail surfaces.
Also, if preferred, a pad forming space can be prepared using the area inside the slider rails. As a result, a considerable number of pads can be formed to assure stable CSS operations. In addition, a variety of pad shapes can be arranged.
At least some of the pads can be made of diamond-like carbon, which is very hard. Thus, the pad hardness can be enhanced, resulting in reduced wear of the pads and prolonged durability. This will prolong the service life of the disk system.
The pads typically project about 10 nm below the rail surfaces. With this mechanism, the pad-disk adsorption prevention function can be maintained over an extended period, even if the pads have been considerably defaced. This will also prolong the service life of the disk system.
Thus, the basic configuration of the invention includes several slider rails with rail surfaces projecting from a base plate and extending lengthwise on the base plate to generate a hovering force, with pads attached to the base plate projecting more than than the rail surfaces. In addition, this invention also features the use of a disk having at least a cleaning zone with a greater degree of roughness compared to the projecting amount formed by the pads attached to the head slider. The cleaning zone can scrape off the deposits formed on the rail surfaces by polishing the rail surfaces on the cleaning zone, so that the floating stability is maintained over an extended period, preventing a failure from occurring.
The cleaning zone can typically be installed inside and/or outside of the CSS zone of the disk. Therefore, either the inner or outer empty space of the CSS zone can be used for cleaning. Cleaning of the rail surfaces can be performed by the movement of the slider toward the inner or outer side o
Fujitsu Limited
Greer Burns & Crain Ltd.
Renner Craig A.
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