Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Disk record
Reexamination Certificate
2000-06-20
2002-09-24
Heinz, A. J. (Department: 2754)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Disk record
Reexamination Certificate
active
06456453
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic disk drive used in, for example, an external storage device of a computer.
2. Description of the Related Art
A conventional magnetic disk drive is described.
FIG. 14
is a plan view schematically showing the conventional magnetic disk drive.
FIG. 15
is a right side view of the main portion as viewed in the direction of arrow XIV in
FIG. 14
, in which a chassis and a bottom cover in the conventional magnetic disk drive are in an assembled state.
FIG. 16
is a plan view of the bottom cover in the conventional magnetic disk drive.
FIG. 17
shows measured values obtained when a body of the conventional magnetic disk drive is resonating.
In
FIGS. 14
to
16
, a chassis
31
is a thin iron plate, and comprises a flat section
31
a
which is a substantially rectangular flat surface, side walls
31
b
1
and
31
b
2
formed vertically from both longer sides of the flat section
31
a
, and a side wall
31
c
formed by erecting vertically a portion of one of the shorter sides of the flat section
31
a
. Near a boundary between the flat section
31
a
and the side wall
31
b
l, recess-shaped holding sections
32
which are recessed from the flat section
31
a
are formed at two locations in a longitudinal direction of the chassis
31
. Similarly, near a boundary between the side wall
31
b
2
and the flat section
31
a
, recess-shaped holding sections
32
are formed at two locations in the longitudinal direction of the chassis
31
. The sets of two holding sections
32
near the two boundaries of the chassis
31
are disposed parallel to each other with
1
respect to a center line X
3
—X
3
extending in the longitudinal direction of the chassis
31
.
Each holding section
32
includes a tapering section
32
a
and a pedestal
32
b
which is a top portion formed continuously with its corresponding tapering section
32
a
and formed parallel to the flat surface corresponding to the flat section
31
a
, with a through hole
32
c
passing vertically through substantially the center of its corresponding pedestal
32
b.
A head transporting device
33
comprises a head carriage
34
including a head arm for carrying a magnetic head (not shown) at an end thereof, a guide shaft
35
which is inserted into the head carriage
34
, and a stepping motor
36
to which one end of the guide shaft
35
is fitted. The stepping motor
36
allows the head carriage
34
to move in the longitudinal direction of the chassis
31
. The head transporting device
33
which is inserted into a hole (not shown) formed in the side wall
31
c
is secured to the chassis
31
using a desired securing means such as screwing.
A spindle motor
37
is mounted to the flat section
31
a
of the chassis
31
from below using a desired mounting means such as screwing. Although not shown, other component parts are mounted to the chassis
31
to form a body A
1
.
As shown in
FIG. 16
, a bottom cover
38
is a thin iron plate, and comprises a bottom plate
38
a
which is a substantially rectangular flat surface, and side walls
38
b
1
and
38
b
2
formed vertically from both longer sides of the bottom plate
38
a
. Near a boundary between the bottom plate
38
a
and the side wall
38
b
1
, protruding holding sections
39
formed by indenting portions of the bottom plate
38
a
from the bottom side to the top side are formed at two locations in a longitudinal direction of the bottom cover
38
. Similarly, near a boundary between the side wall
38
b
2
and the bottom plate
38
a
, protruding holding sections
39
are formed at two locations in the longitudinal direction. The sets of two holding sections near the two boundaries of the bottom plate
38
a
are disposed parallel to each other with respect to a center line X
4
—X
4
extending in the longitudinal direction.
Similarly to each holding section
32
of the chassis
31
, each holding section
39
includes a tapering section
39
a
and a pedestal
39
b
which is a top portion formed continuously with its corresponding tapering section
39
a
and formed parallel to the flat surface of the bottom plate
38
a
, with a hole
39
c
passing vertically through substantially the center of its corresponding pedestal
39
b.
As shown in
FIG. 15
, the bottom cover
38
is mounted to the chassis
31
so as to cover the bottom side of the chassis
31
and so as to make the pedestal
32
b
of each holding section
32
of the chassis
31
contact, that is, abut against the pedestal
39
b
of each holding section
39
of the bottom cover
38
. This causes the hole
39
c
in each holding section
39
of the bottom cover
38
and the hole
32
c
of each holding section
32
of the chassis
31
to be in a connected state. Holding means, such as screws
40
, are inserted into the holes
39
c
and the corresponding holes
32
c
in the connected state in order to secure the bottom cover
38
and the chassis
31
together. Accordingly, the bottom cover
38
is completely secured to the chassis
31
at four locations with the screws. By mounting the bottom cover
38
to the body A
1
, the magnetic disk drive is constructed.
The magnetic disk drive is used as an external storage device of a computer, such as a desktop PC, and is placed in various external environmental conditions. It functions to perform read/write operations with a magnetic head which sandwiches a magnetic floppy disk from both sides thereof.
Therefore, when the magnetic disk drive is vibrated by changes in some external environmental condition, the vibration acts on the magnetic head through the head carriage, so that the read/write operations may be affected in some way.
Here, as shown in
FIG. 17
, an evaluation of the vibration of the body A
1
was carried out by vibrating the entire conventional magnetic disk drive and changing the oscillation frequency thereof using a measuring device called a servo analyzer. In
FIG. 17
, the vertical axis represents a ratio in which an output acceleration a
1
of the body A
1
is divided by an input acceleration a
2
to the magnetic disk drive (a
1
/a
2
), and the horizontal axis represents the oscillation frequency (in Hz).
According to
FIG. 17
, at input frequencies of 230 Hz and 317 Hz, the a
1
/a
2
level become steep and reach peak points. From
FIG. 17
, it can be seen that the body A
1
resonates when the outside vibration has vibration frequencies of 230 Hz and 317 Hz.
As can be understood from the foregoing description, in the conventional magnetic disk drive, the chassis
31
and the bottom cover
38
are completely secured together by the four holding sections
32
of the chassis
31
and the four holding sections
39
of the bottom cover
38
, so that any vibration and shock exerted to the bottom cover
38
from the outside are directly transmitted to the body A
1
. Therefore, as shown in
FIG. 17
, resonance occurs at 200 to 350 Hz. When the body A
1
resonates, the spindle motor
37
, the head carriage
34
, and the like are adversely affected, so that, for example, variations in rotation occur therein. In particular, the head carriage
34
itself has a natural resonance mode near 300 Hz, so that the head carriage
34
is greatly affected, causing a side of the head arm where the magnetic disk is gripped to open, resulting in read/write operation errors.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to make it possible to effectively reduce externally applied vibration and shock by making a body comprising a chassis to which component parts are mounted rotatable with reference to a location situated away from the center of gravity of the body.
To this end, according to the present invention, there is provided a magnetic disk drive comprising:
a body including a chassis formed of a flat plate and at least a spindle motor and a head carriage that are mounted to the chassis;
a bottom cover mounted so as to cover the chassis; and
holding means for holding the chassis and the bottom cover;
wherein the holding means is disposed on a support li
Mizuta Koji
Wauke Tomokuni
Yamamoto Akihito
Alps Electric Co. ,Ltd.
Heinz A. J.
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