Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Disk record
Reexamination Certificate
2001-10-05
2003-10-14
Ometz, David L. (Department: 2653)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Disk record
C360S265700, C360S265800
Reexamination Certificate
active
06633452
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a disk drive apparatus, a hard disk drive, and an enclosure for a hard disk drive.
2. Description of the Related Art
As is well known, a hard disk drive has often been used as a main storage medium for data in a computer.
FIG. 9
shows a typical example of a construction of a hard disk drive. In a hard disk drive
1
shown in
FIG. 9
, a disk enclosure
4
is constituted of a bottomed box-shaped base
2
with an opening in the upper part thereof and a cover
3
for sealing the upper opening of the base
2
. In the disk enclosure
4
is provided a spindle motor
5
having an in-hub construction on the side of the base
2
. On the spindle motor
5
are stacked a predetermined number of magnetic disks
6
, which disks are fixed to a rotor
5
a
of the spindle motor
5
by means of a top clamp
7
. These magnetic disks
6
are rotationally driven at a predetermined rotational speed by the spindle motor
5
.
Also, in the disk enclosure
4
is provided an actuator
10
. The actuator
10
is rotatably fixed to the base
2
via a pivot
11
in an intermediate portion. In a tip end portion of the actuator
10
, there is provided a magnetic head
12
for reading and writing data stored on the magnetic disks
6
. Also, at the rear end of the actuator
10
is provided a voice coil
13
. On the other hand, the base
2
is provided with a stator
14
, which cooperates with the voice coil
13
, so as to be opposed to the voice coil
13
. The voice coil
13
and the stator
14
constitutes a voice coil motor. This voice coil motor pivotally moves the actuator
10
around the pivot
11
by utilizing a magnetic force created between the voice coil
13
and the stator
14
by the supply of an electric current to the voice coil
13
.
3. Problems to be Solved by the Invention:
In recent years, the throughput of a computer has increased remarkably, and also the storage capacity of the hard disk drive
1
has increased. Accordingly, the speed of data access must be increased. As a result, the rotational speed of the magnetic disk
6
has become dramatically higher than that of the conventional disk, which has resulted in various problems that the background art does not have.
For example, a noise problem arises when the hard disk drive
1
is operated. In the hard disk drive
1
, a noise (sympathetic sound) due to resonance is sometimes produced in the cover
3
having a lower stiffness than the base
2
. The reason for this is probably that the cover
3
is resonated by vibrations transmitted to the cover
3
through the base
2
when the magnetic disks
6
are rotated or by vibrations caused when the actuator
10
is operated, whereby a noise is produced.
To prevent this problem, conventionally, the natural frequency of the base
2
has been shifted from the frequency of the magnetic disk
6
in rotation and the frequency of the actuator
10
in operation by, for example, installing various types of damping members in several portions of the hard disk drive
1
, whereby measures against resonance have been taken. However, a demand for reduction in noise has become increasingly strong. Moreover, the number of parts constituting the hard disk drive
1
is increased by the addition of the damping members, which leads to a rise in manufacturing cost. Therefore, such measures do not necessarily provide the best solution to the problem.
Also, there arises another problem of reliability when data is read and written. Specifically, with the increase in storage capacity, the recording density of the magnetic disk
6
has increased dramatically, and the distance between tracks in the radial direction of the magnetic disk
6
has become smaller. As a result, when data is read or written with the magnetic head
12
, high accuracy is required in positioning the magnetic head
12
with respect to the magnetic disk
6
(more particularly, the track of the magnetic disk
6
in which the objective data is stored).
One of the factors greatly affecting the positioning accuracy for the magnetic head
12
is a change of the relative positional relationship between the actuator
10
and the magnetic disk
6
caused when the actuator
10
is operated. If this relative positional relationship changes, the positioning accuracy for the magnetic head
12
with respect to the magnetic disk
6
decreases. As a result, an error occurs in reading and writing data from and on the magnetic disk
6
, or the reading and writing of data becomes impossible, which presents a problem in that the reliability of the hard disk drive
1
decreases.
The present invention has been made to solve the above-described technical problems, and accordingly a principal object thereof is to provide a disk drive apparatus capable of effectively reducing noise in operation. Also, another object of the present invention is to provide a disk drive apparatus, a hard disk drive, and an enclosure therefor capable of enhancing the reliability.
SUMMARY OF THE INVENTION
To achieve the above objects, the inventors made a study earnestly to determine causes of a decrease in positioning accuracy for the magnetic head
12
when the actuator
10
is operated. As the result of the study, we found that the fact that the pivot
11
for supporting the actuator
10
is displaced in a different direction with respect to the axis thereof, that is, it is tilted (hereinafter, this phenomenon is referred to as a tilt) contributes greatly to the above problems.
As shown in
FIG. 10A
, the pivot
11
is mounted to a boss
16
provided at the bottom of the base
2
. As shown in
FIG. 10B
, the boss
16
is formed with a recess
16
a
in which the lower end portion of the pivot
11
is set and a screw hole
16
b
formed in the central portion of the recess
16
a
. The pivot
11
is attached to the base
2
by fastening the lower end portion thereof set in the recess
16
a
with a screw
18
from the back face of the base
2
through the screw hole
16
b
. Further, the upper end portion of the pivot
11
is fixed to the cover
3
with a screw
19
. However, the cover
3
has a lower stiffness than the base
2
, so that this fixation is complementary. Therefore, the pivot
11
is substantially in a state in which the lower end portion thereof is supported on the base
2
in a cantilever manner. Whether a tilt of the pivot
11
occurs or not depends on the stiffness of the bottom portion of the base
2
.
If the frequency (resonance frequency) when the actuator
10
is driven is close to the natural frequency (resonance frequency) of the base
2
, a tilt of the pivot
11
is produced by resonance. The tilt of the pivot
11
for the actuator
10
occurring in this manner has an adverse influence on the positioning accuracy for the magnetic head
12
with respect to the magnetic disk
6
.
To restrain the tilt of the pivot
11
, an increase in stiffness of the bottom portion of the base
2
is thought, and for this purpose, an increase in the thickness of the bottom plate of the base
2
is thought. However, the increase in the thickness of the bottom plate of the base
2
decreases an internal space of the disk enclosure
4
, so that an increase in the number of magnetic disks
6
demanded by an increase in storage capacity in recent years is sometimes hindered.
The disk drive apparatus in accordance with the present invention, which has been made in consideration of such a respect, is characterized in that in an enclosure for containing a disk driving source and an actuator, a rib extending from a peripheral wall toward a rotating shaft of the actuator is provided on a bottom plate for supporting the rotating shaft. Such a rib can reinforce the bottom plate of the enclosure in the vicinity of the rotating shaft. Also, when the rib is provided on both sides of the axis of the rotating shaft, a connection rib for connecting both of the ribs to each other is formed, whereby the reinforcing effect is further increased.
Such a disk drive apparatus is not limited to what is called a hard disk drive, and may b
Hirasaka Yoshihiro
Ohta Mutsuro
Serizawa Kohji
Takahasi Keishi
Blouin Mark S
Bracewell & Peterson, L.L.P.
Martin Robert B.
Ometz David L.
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