Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specific detail of storage medium support or motion production
Reexamination Certificate
1998-03-13
2003-01-14
Miller, Brian E. (Department: 2652)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specific detail of storage medium support or motion production
C360S099080
Reexamination Certificate
active
06507555
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a disk drive apparatus that allows stable recording and playback by suppressing undesirable vibration and noise caused by the unbalance of a disk as a removable recording medium.
BACKGROUND ART
Recently, in a disk drive apparatus for driving disks as removable recording media (for example, CD-ROM), disk rotational speeds increase in order to increase data transfer speed. However, disks contain mass imbalance due to thickness nonuniformity, etc. If such disks are rotated at a high speed, a nonuniform centrifugal force (imbalance force) is exerted on the center of disk rotation, resulting in the problem that the vibration due to the imbalance force is transmitted to the entire apparatus. Since the magnitude of the imbalance force increases with the square of the rotational frequency, the vibration increase rapidly as the disk rotational speed is raised. Accordingly, rotating disks at high speed has involved the problems that noise is generated by the vibration, that the bearing of the spindle motor for driving disks is damaged, and that stable recording and playback are impossible. A further problem has been that when a disk drive apparatus is built in a computer or the like, the vibrations are transmitted to other peripheral devices, causing ill effects.
Therefore, in order to increase data transfer rates by increasing disk rotational speeds, it has been necessary to suppress undesirable vibrations caused by disk imbalance.
An example of a conventional disk drive apparatus will be described below with reference to drawing.
FIG. 24
is a perspective view showing the conventional disk drive apparatus. In
FIG. 24
, a disk
1
is driven for rotation by a spindle motor
2
, and a head
3
reads data recorded on the disk
1
or writes data to the disk
1
. A head driving mechanism
5
consists of a rack and pinion or the like, and converts the rotary motion of a head driving motor
4
into a rectilinear motion which is transmitted to the head
3
. By this head driving mechanism
5
, the head
3
is moved radially across the disk
1
. The spindle motor
2
, the head driving motor
4
, and the head driving mechanism
5
are mounted on a sub-base
6
. Vibration and shock transmitted to the sub-base
6
from outside the apparatus are dampened by an insulator
7
(elastic member); the sub-base
6
is mounted on a main base
8
via the insulator
7
. Main part of the disk drive apparatus is constructed so that it can be mounted inside a computer apparatus or the like by using a frame
9
attached to the main base
8
.
FIG. 25
is a cross-sectional side view showing the vicinity of the spindle motor
2
in the conventional disk drive apparatus. A turn table
110
is fixed to a shaft
21
of the spindle motor
2
and supports a clamp area
11
of the disk
1
in rotatable fashion. A boss
14
which engages with a clamp hole
12
in the disk
1
is formed integrally with the turn table
110
. The centering of the disk
1
is achieved by engaging the disk
1
with the boss
14
. In the upper part of the boss
14
is formed a positioning hole
113
, and further, a counter yoke
15
is fixed.
A clamper
116
has a center projection
17
for centering, which engages with the positioning hole
113
formed in the turn table
110
, and around which a ring-shaped magnet
18
is fixed. A flat contacting portion
19
which contacts the disk
1
is formed on the lower surface of the damper
116
.
In the thus constructed conventional disk drive apparatus, when loading the disk
1
, the disk
1
is placed on the turn table
110
with the clamp hole
12
engaging on the boss
14
. At this time, the disk
1
is held in position by the attractive force acting between the magnet
18
built into the clamper
116
and the counter yoke
15
fixed to the turn table
110
. The thus held disk
1
is driven for rotation by the spindle motor
2
in integral fashion with the turn table
110
and the damper
116
. When removing the disk
1
, the damper
116
and the turn table
110
are driven by the driving force of a disk loading motor (not shown) in such direction that both depart from each other, so that the disk
1
becomes in a state to be removable.
However, with the conventional disk drive construction described above, if the disk
1
contains mass imbalance due to thickness nonuniformity, etc., when the disk
1
is rotated at high speed a centrifugal force (imbalance force) F acts upon the center of mass, G
1
, of the disk
1
shown in FIG.
25
. Its acting direction turns with the rotation of the disk
1
. This imbalance force F is transmitted to the sub-base
6
via the turn table
110
and spindle motor
2
; since the sub-base
6
is supported on the insulator
7
formed of an elastic member, the sub-base
6
wobbles greatly because of the imbalance force, while deforming the insulator
7
. Since the magnitude of the imbalance force F is proportional to the product of its unbalance amount (expressed in gcm) and the square of the rotational frequency, the vibration acceleration of the sub-base
6
also increases rapidly, approximately in proportion to the square of the rotational frequency of the disk
1
. As a result, noise is generated by resonances of the sub-base
6
itself and the head driving mechanism
5
mounted on the sub-base
6
, and the disk
1
and the head
3
vibrate greatly, leading to the problem that stable recording and playback cannot be made.
In order to cope with this problem, in the conventional disk drive apparatus such a measure has been taken as to reduce the amplitude of vibration of the sub-base
6
by increasing the spring constant of the insulator
7
or by inserting an elastic member such as a plate spring between the sub-base
6
and the main base
8
. Increasing the stiffness of the joint portion between the sub-base
6
and the main base
8
, however, this measure led to the problem that when vibration or shock is applied from outside the apparatus, the vibration or shock is directly transmitted to the sub-base
6
on which the disk
1
, the head
3
, etc. are mounted, rendering stable recording and playback impossible and degrading the anti-vibration, anti-shock characteristics of the apparatus.
The above measure has also involved the problem that the vibration of the sub-base
6
caused by the imbalance force F is transmitted to the outside of the disk drive apparatus via the main base
8
and frame
9
, causing ill effects to other devices than the disk drive apparatus, which are mounted inside the computer apparatus. Furthermore, there has arisen the problem that a large side pressure is exerted on the bearing of the spindle motor
2
by the imbalance force F, increasing bearing damaging torque and leading to damage to the bearing, eventually shortening the bearing life.
In view of the above-outlined problems, the present invention provides a disk drive apparatus that ensures stable recording or reproducing even when an unbalanced disk is rotated at high speed, and that has high reliability against shock and vibration from outside the apparatus and achieves high data transfer rates by rotating the disk at high speed.
DISCLOSURE OF INVENTION
In order to solve the above-mentioned problems, the disk drive apparatus of the present invention is constructed such that a balancer having a hollow ring member containing therein a plurality of spherical bodies or a liquid is mounted so as to be rotatable with a disk loaded into the disk drive apparatus; hereinafter, specific means will be shown.
A disk drive apparatus according to the present invention comprises:
a sub-base to which a spindle motor for rotationally driving a loaded disk is fixed;
a main base on which the sub-base is mounted via an elastic member; and
a balancer mounted rotatably with the loaded disk, and having a hollow ring member containing therein a plurality of spherical bodies.
Thus, according to the disk drive apparatus of the present invention, a disk drive apparatus can be achieved that has high vibration and shock resistant characteristics and that is capa
Fukuyama Sachio
Kikugawa Masaaki
Masaki Kiyoshi
Mihara Kazuhiro
Urayama Noriaki
Akin Gump Strauss Hauer & Feld L.L.P.
Matsushita Electric - Industrial Co., Ltd.
Miller Brian E.
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