Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Disk record
Reexamination Certificate
2001-09-19
2003-12-02
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Disk record
Reexamination Certificate
active
06657812
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a disk drive apparatus that is represented by a hard disk drive, and in particular, to technology for improving a collection efficiency of a dust filter in a disk drive apparatus.
2. Background Art
A hard disk drive that is the most general as data storage means of a computer (hereinafter, an HDD) has the structure of locating one or a plurality of magnetic disk platters in the same shaft and driving the one or plurality of magnetic disk platters by a spindle motor. Reading and writing is performed by a magnetic head which is provided with facing respective surfaces of the magnetic disk, and this magnetic head is driven by an actuator, that is, a voice coil motor (hereinafter, a VCM) in general. The above-described magnetic disk, magnetic head, and actuator are contained in a housing that is called a disk enclosure. The disk enclosure consists of a base made of a shallow-box-like aluminum alloy and a top cover sealing an opening section of the base.
Main technical subjects in HDDs are to improve memory capacity per magnetic disk platter, and to improve reading speed of data, stored in a magnetic disk, and writing speed of data into the magnetic disk. As for the latter, it is possible to improve reading and writing speed of data by shortening seek time when the magnetic head moves to a necessary track on the magnetic disk. Since the magnetic head is driven by a VCM as described above, it is possible to accelerate the seek time by enhancing the performance of this VCM. In order to enhance the performance of the VCM, it is sufficient just to adopt another permanent magnet that configures the VCM and has a stronger magnetic characteristic, or to enlarge a magnetic field applied to the voice coil by making the permanent magnet thicker. Nevertheless, the enhancement of the magnetic characteristic of a permanent magnet is also near to its limit. Furthermore, in an HDD that is requested to be small, there is a limit to make a permanent magnet thicker than a current one.
In addition, by accelerating the rotational speed of a magnetic disk, it is possible to improve the reading and writing speed of data. Nevertheless, if the rotational speed of a magnetic disk is accelerated, a probability that dust collides with a magnetic head becomes higher even if the same number of dust exists in an HDD. This collision may cause a damage of the magnetic head, and magnetic disk. On the other hand, because the floating height of a magnetic head from a magnetic disk is also lowered so as to correspond to capacity expansion of the magnetic disk, there is a possibility of collision even if the dust has small size that has not been a big issue up to now. Therefore, dust reduction in an HDD becomes an important subject.
Because a disk enclosure configuring an HDD consists of a base and a top cover, and an opening section of the base is sealed by the top cover, dust hardly enters into the HDD after the assembly of the HDD. Therefore, dust becoming a problem is mixed inside the disk enclosure in the process of assembling the HDD. The HDD has a catching mechanism to catch this dust.
FIGS. 9 and 10
are perspective views showing the configuration of a disk enclosure
116
configuring a conventional HDD.
FIG. 9
shows a condition that a base
112
and a top cover
114
are separated from each other, and
FIG. 10
shows a condition that the top cover
114
is mounted on the base
112
. In addition, the top cover
114
shown in
FIG. 9
is a backside facing the base
112
. Furthermore, in
FIG. 10
, in order that the inside of the base
112
can be observed, the top cover
114
is shown in a transparent condition.
The base
112
has a peripheral wall
112
a
that is stood around its outer periphery. In an area surrounded by the peripheral wall
112
a
, there are a disk container
112
b
containing a disk assembly that consists of a magnetic disk and a spindle motor rotationally driving the magnetic disk, and an actuator container
112
c
accommodating an actuator mechanism for making a magnetic head seek a track on the magnetic disk. The catching mechanism
113
of dust is located in the outer periphery of the disk container
112
b.
An enlarged top view showing the vicinity of the catching mechanism
113
is shown in FIG.
4
. The catching mechanism
113
has a partition wall
113
a
, stood at a predetermined distance from the peripheral wall
112
a
of the base
112
, and a filter
113
b
, located between the peripheral wall
112
a
and partition wall
113
a
. A catching chamber
113
e
is formed between the partition wall
113
a
and peripheral wall
112
a
, and an inlet
113
c
is formed in one end of the catching chamber
113
e
and an outlet
113
d
is in another end.
Since the magnetic disk turns counterclockwise (shown by a dotted arrow in the figure), a counterclockwise air stream occurs in the disk container
112
b
. Dust in the HDD floats with this air stream. As for this air stream, because linear velocity caused by the rotation of the magnetic disk becomes larger as going to the outer periphery, dust moves along the peripheral wall
112
a
. In addition, the dust enters the catching mechanism
113
from the inlet
113
c
with the air stream, and is caught by the filter
113
b
. The air stream after the dust being caught is exhausted from the outlet
113
d
. Although the dust in the HDD is caught in this manner, it is requested to improve a collection efficiency of the filter
113
b
in connection with accelerating the rotation speed of the magnetic disk. Then, the present invention is intended to improve a dust collection efficiency in a disk drive apparatus represented by an HDD.
SUMMARY OF THE INVENTION
As an index for measuring the collection efficiency in the filter
113
b
, there is the pressure drop before and after the filter
113
b
. This is an evaluation method adopted also in IDEMA (International Disk Drive Equipment Material Association). Thus, in
FIG. 4
, let pressure before the filter
113
b
be Pf and let pressure after the filter
113
b
be Pr. The larger the pressure drop obtained from Pf-Pr is, the more volume of air passes the filter
113
b
. Assuming that dust is included uniformly in the air passing the catching mechanism
113
, that more volume of air passes the filter
113
b
means that more volume of dust collides against and is caught by the filter
113
b
. Therefore, the present inventor investigated to enlarge the pressure drop (L) obtained from Pf-Pr.
It is possible to enlarge the pressure drop (L) by increasing Pf or decreasing Pr. Then, first, a review about structure of the catching mechanism
113
was performed about whether Pr could be increased. In order to increase Pr, it is effective to enhance airtightness in the catching chamber
113
e
that is a space formed by the partition wall
113
a
, filter
113
b
, peripheral wall
112
a
, and top cover
114
. Nevertheless, it is confirmed that airtightness of the catching chamber
113
e
is not enough in the catching mechanism
113
of the conventional HDD.
As shown in
FIGS. 9 and 10
, a gasket
115
is provided in a back face of the top cover
114
, and when the top cover
114
is mounted on the base
112
, the gasket
115
is pressed on a top face of the peripheral wall
112
a
in the base
112
to secure airtightness against the outside. Here, a partial cross section of the catching mechanism
113
is shown in
FIG. 5A
, and according to the figure, a gap is formed between the partition wall
113
a
and top cover
114
. This is because there was concern about not being able to secure the airtightness in the HDD because of the lack of contact pressure of the gasket
115
and peripheral wall
112
a
if the partition wall
113
a
contacts to the top cover
114
. In general, although the base
112
consists of aluminum alloy formed by die casting, it is difficult to form highly precise parts by die casting. Owing to that, conventionally, the base
112
has been designed so that the contact of the partition wall
113
a
and top cover
Hirasaka Yoshihiro
Serizawa Kohji
Bracewell & Patterson L.L.P.
Evans Jefferson
Hitachi Global Storage Technologies - Netherlands B.V.
Martin Robert B.
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