Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specific detail of storage medium support or motion production
Reexamination Certificate
2000-06-08
2004-05-25
Whitehead, Jr., Carl (Department: 2813)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specific detail of storage medium support or motion production
Reexamination Certificate
active
06741544
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a disk drive apparatus capable of carrying out stable recording and reproduction by suppressing undesirable vibration and noise caused by an imbalance on a disk used as a recording medium.
PRIOR ART
In recent years, in disk drive apparatuses for recording/reproducing data, high-speed disk rotation is being advanced to improve data transfer rate. For example, in a CD-ROM disk drive apparatus, its rotation speed has increased from a conventional value of the order of 5000 rpm to 6000 rpm or more. This tendency is similarly shown not only in the half-height disk drive apparatuses for desktop computers but also the low-profile disk drive apparatuses for notebook computers.
However, there are various disks; some disks have a mass imbalance due to nonuniform thickness, and other disks have a mass imbalance due to the paper seal stuck thereto to indicate the contents recorded thereon. The amount of the mass imbalance of the disk reaches about 1 gcm in the case when the amount is large. When this kind of disk is rotated at high speed, an eccentric centrifugal force (an imbalance force) acts on the rotation center of the disk, thereby causing a problem wherein the vibration due to the imbalance force is transmitted to the whole of the device. The magnitude of this imbalance force increases in proportion to the square of rotation frequency (Hz) (rotation frequency is the revolutions per unit time (revolutions/sec) of a disk
501
). For example, when increasing the rotation speed of a disk having a mass imbalance of 1 gcm by only about 10%, from 5400 rpm to 600 rpm, the imbalance force increases about 1.2 times, and the vibration also increases significantly.
When the mass of the disk is M (g), and when the distance from the center of the disk to the center of gravity of the disk is L (cm), the mass imbalance amount A (gcm) is represented by A=M×L.
When this kind of unbalanced disk is rotated at high speed, noise occurs due to its vibration, the bearings of the spindle motor for rotating the disk are damaged, thereby causing a problem wherein stable recording and reproduction cannot be attained.
Furthermore, when this kind of disk drive apparatus is built in an apparatus such as a computer, the vibration is transmitted to other devices inside the apparatus, thereby also causing a problem of adversely affecting the devices.
For these reasons, to improve data transfer rate by rotating the disk at high speed, it is necessary to accomplish a task of suppressing undesirable vibration due to the mass imbalance of the disk.
An example of a conventional disk drive apparatus will be described below referring to the drawings.
FIG. 72
is a perspective view showing the main unit of the conventional disk drive apparatus. Referring to
FIG. 72
, a disk
1
is rotated by a spindle motor
2
; and a head
3
reads data recorded on the disk
1
or writes data on the disk
1
. A head drive mechanism
5
, comprising a rack, a pinion and the like, converts the rotation motion of a head drive motor
4
into a linear motion, and transmits it to the head
3
. The head
3
is configured so as to be moved in the radial direction of the disk
1
by this head drive mechanism
5
. The spindle motor
2
, the head drive motor
4
and the head drive mechanism
5
are mounted on a sub-base
6
. Vibration and impact transmitted from outside the device to the sub-base
6
are dampened by insulators
7
(elastic bodies), and the sub-base
6
is mounted on a main base
8
via these insulators
7
. The main unit of the disk drive apparatus shown in
FIG. 72
is configured so as to be built on a computer or the like via a frame (not shown) installed in the main base
8
.
FIG. 73
is a side sectional view showing the vicinity of the spindle motor
2
of the conventional disk drive apparatus. A turntable
110
is secured to the shaft
21
of the spindle motor
2
and rotatably supports the clamp area
11
of the disk
1
. Inside the boss
14
formed on the turntable
110
, a positioning ball
116
making contact with the corner portion of the clamp hole
12
of the disk
1
by virtue of a pressing means
113
, such as a coil spring, is built in. In this way, the disk
1
is disposed at a predetermined position by the pressing operation of the positioning ball
116
.
In the conventional disk drive apparatus configured as describe above, in the condition wherein the disk
1
is disposed and clamped on the turntable
110
, by making the positioning ball
116
contact with the corner portion of the clamp hole
12
, the disk
1
is aligned and held on the turntable
110
by the pressing force of the pressing means
113
. The disk
1
held in this way is rotated integrally with the turntable
110
by the spindle motor
2
.
However, in the conventional disk drive apparatus having the above-mentioned configuration, if the disk
1
having a mass imbalance due to nonuniform thickness, a seal, etc. stuck thereon is mounted and rotated at high speed, a centrifugal force (an imbalance force) F acts on the center of gravity G
1
of the disk
1
shown in FIG.
73
. The direction of the action rotates as the disk
1
rotates. This imbalance force F is transmitted to the sub-base
6
via the turntable
110
and the spindle motor
2
; however, since the sub-base
6
is supported by the insulators
7
used as elastic bodies, it is whirled significantly by the imbalance force F while the insulators
7
are deformed. Since the magnitude of the imbalance force F is proportional to the product of the mass imbalance amount (represented by the unit of gcm) and the square of the rotation frequency, the vibration acceleration of the sub-base
6
increases drastically in close proportion to the square of the rotation frequency of the disk
1
. As a result, such problems occur that noise was caused due to the resonance of the sub-base
6
itself and the head drive mechanism
5
mounted on the sub-base
6
, and stable recording and reproduction became impossible due to significant vibration of the disk
1
and the head
3
.
To cope with the above-mentioned problems, in the conventional disk drive apparatus, the spring constant of the insulators
7
was raised, or an elastic material, such as a leaf spring, was provided between the sub-base
6
and the main base
8
as countermeasures to suppress the vibration amplitude of the sub-base
6
.
However, if the rigidity of the connection portion between the sub-base
6
and the main base
8
was raised in this way, when vibration and impact were applied reversely from outside the drive device to the disk drive apparatus, the vibration and impact were directly transmitted to the sub-base
6
on which the disk
1
, the head
3
and the like were mounted, and stable recording and reproduction became impossible, thereby causing a problem of reducing the so-called vibration-resistant and impact-resistant characteristics.
Furthermore, the vibration of the sub-base
6
due to the imbalance force F was transmitted to the outside of the disk drive apparatus via the main base
8
and the like, thereby causing a problem of adversely affecting other devices in the computer in which this disk drive apparatus was built.
Moreover, a large side pressure was applied to the bearings of the spindle motor
2
by the imbalance force F, whereby the loss of the shaft torque increased, and the bearings were damaged, thereby to cause a problem of shortening the service life of the bearings.
DISCLOSURE OF THE INVENTION
In consideration of the above-mentioned problems, the present invention is intended to provide a disk drive apparatus capable of carrying out stable recording and reproduction even when an unbalanced disk is rotated at high speed, and also capable of carrying out high-rate transfer while having high reliability in preventing vibration and impact from outside the device.
In order to solve the above-mentioned problems, the disk drive apparatus of the present invention is a device wherein a balancer having a ring-shaped track portion accommodating balance members
Fukuyama Sachio
Kikugawa Masaaki
Maruoka Makoto
Masaki Kiyoshi
Mihara Kazuhiro
Akin Gump Strauss Hauer & Feld L.L.P.
Dolan Jennifer M
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