U.S. patent application number 10/695043 was filed with the patent office on 2004-05-13 for disk drive apparatus.
This patent application is currently assigned to Matsushita Electric Industrial Co., Ltd.. Invention is credited to Fukuyama, Sachio, Kikugawa, Masaaki, Masaki, Kiyoshi, Mihara, Kazuhiro, Urayama, Noriaki, Yoshida, Shuichi.
Application Number | 20040093611 10/695043 |
Document ID | / |
Family ID | 26394605 |
Filed Date | 2004-05-13 |
United States Patent
Application |
20040093611 |
Kind Code |
A1 |
Masaki, Kiyoshi ; et
al. |
May 13, 2004 |
Disk drive apparatus
Abstract
To provide a disk drive apparatus that suppresses undesirable
vibrations due to the unbalance of a loaded disk and achieves
high-speed data transfer, the disk drive apparatus of the present
invention comprises a hollow ring member (23) that contains therein
a plurality of spherical bodies (24) or a liquid (26) to form a
balancer or a balancer, wherein the balancer is formed so as to be
rotatable in integral fashion with a disk, thereby suppressing the
vibrations generated when an unbalanced disk is rotated at high
speed.
Inventors: |
Masaki, Kiyoshi;
(Amagasaki-shi, JP) ; Mihara, Kazuhiro;
(Moriguchi-shi, JP) ; Yoshida, Shuichi;
(Osaka-shi, JP) ; Fukuyama, Sachio;
(Matsuyama-shi, JP) ; Urayama, Noriaki;
(Matsuyama-shi, JP) ; Kikugawa, Masaaki;
(Matsuyama-shi, JP) |
Correspondence
Address: |
AKIN GUMP STRAUSS HAUER & FELD L.L.P.
ONE COMMERCE SQUARE
2005 MARKET STREET, SUITE 2200
PHILADELPHIA
PA
19103-7013
US
|
Assignee: |
Matsushita Electric Industrial Co.,
Ltd.
|
Family ID: |
26394605 |
Appl. No.: |
10/695043 |
Filed: |
October 28, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10695043 |
Oct 28, 2003 |
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10179747 |
Jun 24, 2002 |
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6711116 |
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10179747 |
Jun 24, 2002 |
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08952350 |
Mar 13, 1998 |
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6507555 |
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08952350 |
Mar 13, 1998 |
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PCT/JP97/01032 |
Mar 26, 1997 |
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Current U.S.
Class: |
720/702 ;
G9B/19.029; G9B/19.03; G9B/33.024 |
Current CPC
Class: |
G11B 17/0282 20130101;
F16F 15/363 20130101; G11B 19/2027 20130101; G11B 19/2018 20130101;
G11B 33/08 20130101; G11B 17/0284 20130101 |
Class at
Publication: |
720/702 |
International
Class: |
G11B 019/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 19, 1996 |
JP |
HEI 08-191193 |
Feb 21, 1997 |
JP |
HEI 09-53882 |
Claims
We claim:
1. A motor in combination with an optical disk drive apparatus for
recording or reproducing an interchangeable optical disk,
comprising: a balancer mounted rotatably with a rotor, and having a
hollow ring member containing therein a rotatable balancing member,
and having a center axis positioned substantially concentrically
with a rotational center axis of said motor, wherein said balancer
reduces vibration due to imbalance of said interchangeable optical
disk loaded by a user, and said interchangeable optical disk is
driven for rotation at a frequency higher than the primary
resonance frequency of wobbling vibrations of said interchangeable
optical disk loaded by the user.
2. A motor in combination with an optical disk drive apparatus for
recording or reproducing an interchangeable optical disk, wherein a
balancer having a hollow ring member containing therein a balancing
member and having a center axis positioned substantially
concentrically with a rotational center axis of said motor is
mounted in integral fashion with a spindle shaft, wherein said
balancer reduces vibration due to imbalance of said interchangeable
optical disk loaded by a user, and said interchangeable optical
disk is driven for rotation at a frequency higher than the primary
resonance frequency of wobbling vibrations of said interchangeable
optical disk loaded by the user.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of prior application Ser.
No. 10/179,747, filed Jun. 24, 2002, which is a continuation of
prior application Ser. No. 08/952,350, filed Mar. 13, 1998, which
is a 371 of PCT/JP97/01032, filed Mar. 26, 1997, entitled DISK
DRIVE APPARATUS, the entire disclosure of which is incorporated
herein by reference.
TECHNICAL FIELD
[0002] 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 OF THE INVENTION
[0003] Recently, in a disk drive apparatus for driving disks as
removable recording media (for example, CD-ROM), it has been
proceeding to increase disk rotational speeds 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 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.
[0004] 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.
[0005] An example of a conventional disk drive apparatus will be
described below with reference to drawing.
[0006] 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.
[0007] 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.
[0008] 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 clamper 116.
[0009] 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 clamper 116. When removing the disk 1, the
clamper 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.
[0010] 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, G1, 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.
[0011] In order to coupe 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, has lead 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.
[0012] 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.
[0013] 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.
BRIEF SUMMARY OF THE INVENTION
[0014] 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
integrally with a disk loaded into the disk drive apparatus;
hereinafter, specific means will be shown.
[0015] A disk drive apparatus according to the present invention
comprises:
[0016] a sub-base to which a spindle motor for rotationally driving
a loaded disk is fixed;
[0017] a main base on which the sub-base is mounted via an elastic
member; and
[0018] a balancer mounted rotatably in integral fashion with the
loaded disk, and having a hollow ring member containing therein a
plurality of spherical bodies.
[0019] 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 capable
of high-speed data transfer.
[0020] A disk drive apparatus according to the present invention
comprises:
[0021] a sub-base to which a spindle motor for rotationally driving
a loaded disk is fixed;
[0022] a main base on which the sub-base is mounted via an elastic
member; and
[0023] a balancer mounted rotatably in integral fashion with the
loaded disk, and having a hollow ring member in which a liquid is
sealed.
[0024] Thus, according to the disk drive apparatus of the present
invention, the vibration of the sub-base due to the unbalance of a
loaded disk can be suppressed reliably.
[0025] A disk drive apparatus according to the present invention
comprises:
[0026] a sub-base to which a spindle motor for rotationally driving
a loaded disk is fixed;
[0027] a main base on which the sub-base is mounted via an elastic
member; and
[0028] a balancer having a plurality of hollow ring members and
mounted rotatably in integral fashion with the loaded disk,
[0029] wherein, of the plurality of hollow ring members, at least
one hollow ring member contains spherical bodies therein, and the
other hollow ring member contains a liquid sealed therein.
[0030] Thus, according to the disk drive apparatus of the present
invention, the vibration of the sub-base can be suppressed reliably
regardless of whether a disk with a large unbalance or a disk with
a small unbalance is loaded.
[0031] A disk drive apparatus according to the present invention
comprises:
[0032] a turn table for rotatably supporting a clamp area of the
loaded disk; and
[0033] a clamper, which is formed integrally with the balancer, for
clamping the disk in collaboration with the turn table.
[0034] Thus, according to the disk drive apparatus of the present
invention, the vibration of the sub-base due to the unbalance of a
loaded disk can be suppressed.
[0035] A disk drive apparatus according to the present invention
comprises:
[0036] a turn table, which is formed integrally with the balancer,
for rotatably supporting a clamp area of the loaded disk; and
[0037] a clamper for clamping the disk in collaboration with the
turn table.
[0038] Thus, according to the disk drive apparatus of the present
invention, the vibration of the sub-base due to the unbalance of a
loaded disk can be suppressed, and stable recording or playback can
be done.
[0039] In a disk drive apparatus according to the present
invention, the balancer is provided in integral fashion with a
rotor of the spindle motor.
[0040] Thus, according to the disk drive apparatus of the present
invention, the vibration of the sub-base due to the unbalance of a
loaded disk can be suppressed.
[0041] In a disk drive apparatus according to the present
invention, the vibration resonance frequency of the sub-base due to
deformation of the elastic member is set lower than the rotational
frequency of the disk.
[0042] Thus, according to the disk drive apparatus of the present
invention, a disk drive apparatus can be achieved that ensures
stable recording or playback and that is capable of high-speed
rotation, without degrading its anti-vibration, anti-shock
characteristics.
[0043] In a disk drive apparatus according to the present
invention, the primary resonance frequency of the sub-base due to
deformation of the elastic member in a mechanical vibration in a
direction parallel to the recording surface of the disk is set
lower than the rotational frequency of the disk.
[0044] Thus, according to the disk drive apparatus of the present
invention, since the vibration of the sub-base can be suppressed
reliably irrespective of the magnitude of disk imbalance, a disk
drive apparatus can be achieved that ensures stable recording or
reproducing and that is capable of high-speed rotation, without
degrading its anti-vibration, anti-shock characteristics.
[0045] In a disk drive apparatus according to the present
invention, the primary resonance frequency of the sub-base due to
deformation of the elastic member in a mechanical vibration in a
direction parallel to the recording surface of the disk is set
lower than the maximum rotational frequency of the disk.
[0046] Thus, according to the disk drive apparatus of the present
invention, a disk drive apparatus can be achieved that ensures
stable recording or reproducing and that is capable of high-speed
rotation, without degrading its anti-vibration, anti-shock
characteristics.
[0047] A disk drive apparatus according to the present invention
comprises:
[0048] a turn table, which is provided with a positioning hole
engaging with a spindle shaft of the spindle motor, for rotatably
supporting the clamp area of the loaded disk; and
[0049] a clamper, which is provided with a center shaft engaging
with the positioning hole, for clamping the disk in collaboration
with the turn table,
[0050] wherein the hollow ring member is formed concentrically with
a center axis of the clamper, and the balancer is formed integrally
with the clamper.
[0051] Thus, according to the disk drive apparatus of the present
invention, the vibration of the sub-base can be reduced further
regardless of whether a disk with a large unbalance or a disk with
a small unbalance is loaded.
[0052] A disk drive apparatus according to the present invention
comprises:
[0053] a turn table, which is provided with a positioning hole
engaging with a spindle shaft of the spindle motor, for rotatably
supporting the clamp area of the loaded disk; and
[0054] a clamper, which is provided with a center hole engaging
with the spindle shaft, for clamping the disk in collaboration with
the turn table,
[0055] wherein the hollow ring member is formed concentrically with
a center axis of the center hole in the clamper, and the balancer
is formed integrally with the clamper.
[0056] Thus, according to the disk drive apparatus of the present
invention, the vibration of the sub-base can be suppressed reliably
regardless of whether a disk with a large unbalance or a disk with
a small unbalance is loaded.
[0057] In a disk drive apparatus according to the present
invention, two kinds of spherical bodies of different materials are
arranged alternately and housed in the hollow ring member.
[0058] Accordingly, the disk drive apparatus of the present
invention is capable of suppressing the generation of noise from
the balancer itself.
[0059] In a disk drive apparatus according to the present
invention, a plurality of metal spherical bodies and plastic
spherical bodies are arranged alternately and housed in the hollow
ring member.
[0060] Accordingly, the disk drive apparatus of the present
invention is capable of suppressing the generation of noise from
the balancer itself.
[0061] A disk drive apparatus according to the present invention
comprises: a balancer with magnetic spherical bodies contained in
the hollow ring member; and magnetic field generating means for
holding the magnetic spherical bodies by attraction.
[0062] Accordingly, the disk drive apparatus of the present
invention is capable of suppressing the generation of noise from
the balancer itself.
[0063] A disk drive apparatus according to the present invention
comprises:
[0064] a turn table, to which a counter yoke as a magnetic plate is
fixed, for rotatably supporting the clamp area of the loaded disk;
and
[0065] a clamper which has a built-in magnet for clamping the disk
by an attractive force acting between the magnet and the counter
yoke, and which is formed integrally with a balancer having
magnetic spherical bodies contained in the hollow ring member.
[0066] Thus, according to the disk drive apparatus of the present
invention, not only the vibration of the sub-base due to the
unbalance of a loaded disk can be suppressed reliably, but the
generation of noise from the balancer itself can also be
suppressed, while keeping the number of components to a
minimum.
[0067] In a disk drive apparatus according to the present
invention, an elastic member is attached rigidly around the outer
circumferential surface of the magnet to which the magnetic
spherical bodies are made to adhere.
[0068] Accordingly, the disk drive apparatus of the present
invention is capable of suppressing the generation of noise and
vibration from the balancer itself.
[0069] A disk drive apparatus of the present invention is
constructed such that an elastic member is attached rigidly to a
back yoke which is a magnetic plate fixed to the opposite side of
the magnet from the side thereof facing the counter yoke, and the
magnetic spherical bodies are made to adhere to the elastic member
of the back yoke.
[0070] Accordingly, the disk drive apparatus of the present
invention is capable of suppressing the generation of noise and
vibration from the balancer itself.
[0071] A disk drive apparatus according to the present invention
comprises:
[0072] a turn table, to which a magnet is fixed, for rotatably
supporting the clamp area of the loaded disk; and
[0073] a clamper which has a built-in counter yoke for clamping the
disk by an attractive force acting between the magnet and the
counter yoke, and which is formed integrally with a balancer having
magnetic spherical bodies contained in the hollow ring member.
[0074] Thus, according to the disk drive apparatus of the present
invention, not only the vibration of the sub-base due to the
unbalance of a loaded disk can be suppressed reliably, but the
generation of noise from the balancer itself can also be
suppressed, while keeping the number of components to a
minimum.
[0075] A disk drive apparatus according to the present invention is
constructed such that an elastic member is attached rigidly to the
counter yoke built into the clamper, and the magnetic spherical
bodies are made to adhere to the elastic member.
[0076] Accordingly, the disk drive apparatus of the present
invention is capable of suppressing the generation of noise and
vibration from the balancer itself.
[0077] In a disk drive apparatus according to the present
invention, the hollow ring member housing the spherical bodies is
constructed from an upper case having an opening in a lower side
thereof and a lower case having an opening in an upper side
thereof, and a balancer is provided that has an elastic member
sandwiched between an outer circumferential side wall of the upper
case and an outer circumferential side wall of the lower case.
[0078] Accordingly, the disk drive apparatus of the present
invention is capable of suppressing the generation of noise and
vibration from the balancer itself.
[0079] In a disk drive apparatus according to the present
invention, the hollow ring member housing the spherical bodies is
constructed from an upper case having an opening in a lower side
thereof and a lower case having an opening in an upper side
thereof, and a balancer is provided that has an elastic member
sandwiched between a lower end portion of an outer circumferential
side wall of the upper case and a bottom upper surface of the lower
case.
[0080] Accordingly, the disk drive apparatus of the present
invention is capable of suppressing the generation of noise and
vibration from the balancer itself.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0081] The foregoing summary, as well as the following detailed
description of preferred embodiments of the invention, will be
better understood when read in conjunction with the appended
drawings. For the purpose of illustrating the invention, there is
shown in the drawings embodiments which are presently preferred. It
should be understood, however, that the invention is not limited to
the precise arrangements and instrumentalities shown.
[0082] In the drawings:
[0083] FIG. 1 is a cross-sectional side view showing the vicinity
of a spindle motor 2 in a disk drive apparatus according to a first
embodiment of the present invention.
[0084] FIG. 2 is a cross-sectional plan view showing a hollow ring
member 23 provided on a clamper 16a in the disk drive apparatus of
the first embodiment shown in FIG. 1.
[0085] FIG. 3 is an explanatory diagram showing the case where the
center axis P2 of an outer circumferential wall 25 is displaced
from the rotational center axis P0 of a spindle motor.
[0086] FIG. 4 shows measured values of the vibration acceleration
of a sub-base 6 to illustrate the effect of the first embodiment of
the present invention.
[0087] FIG. 5 is a cross-sectional side view showing the vicinity
of the spindle motor 2 in a disk drive apparatus according to a
second embodiment of the present invention.
[0088] FIG. 6 is a cross-sectional plan view showing a hollow ring
member 23 provided on a clamper 16a in the disk drive apparatus of
the second embodiment shown in FIG. 5.
[0089] FIG. 7 is a cross-sectional side view showing the vicinity
of the spindle motor 2 in a disk drive apparatus according to a
third embodiment of the present invention.
[0090] FIG. 8 is a cross-sectional plan view showing hollow ring
members 23a and 23b provided on a clamper 16b in the disk drive
apparatus of the third embodiment shown in FIG. 7.
[0091] FIG. 9 is a cross-sectional plan view of the hollow ring
members 23a and 23b, explaining the positions of spherical bodies
24 and liquid 26 when the mass imbalance of a disk 1 is small in
the third embodiment shown in FIG. 7.
[0092] FIG. 10 is a cross-sectional side view showing the vicinity
of the spindle motor 2 in a disk drive apparatus according to a
fourth embodiment of the present invention.
[0093] FIG. 11 is a cross-sectional plan view showing a hollow ring
member 23 provided on a clamper in a disk drive apparatus of a
fifth embodiment of the present invention.
[0094] FIG. 12 is a cross-sectional side view showing the vicinity
of the spindle motor 2 in a disk drive apparatus according to a
sixth embodiment of the present invention.
[0095] FIG. 13 is a cross-sectional side view showing the vicinity
of the spindle motor 2 in different conditions in a disk drive
apparatus according to a seventh embodiment of the present
invention.
[0096] FIG. 14 is a cross-sectional side view showing the vicinity
of the spindle motor 2 in a disk drive apparatus according to an
eighth embodiment of the present invention.
[0097] FIG. 15 is a cross-sectional side view showing the vicinity
of the spindle motor 2 in a disk drive apparatus according to a
ninth embodiment of the present invention.
[0098] FIG. 16 is a cross-sectional plan view showing the vicinity
of a hollow ring member 23 and an electromagnet 40 provided on a
turn table 10c in the disk drive apparatus of the ninth embodiment
shown in FIG. 14.
[0099] FIG. 17 is a cross-sectional side view showing the vicinity
of a turn table 110 in a disk drive apparatus according to a tenth
embodiment of the present invention.
[0100] FIG. 18 is an enlarged cross-sectional side view showing the
vicinity of the clamper 16d and turn table 110 in a disk drive
apparatus according to an eleventh embodiment of the present
invention.
[0101] FIG. 19 is a cross-sectional side view showing the vicinity
of the spindle motor 2 in a disk drive apparatus according to a
twelfth embodiment of the present invention.
[0102] FIG. 20 is a cross-sectional side view showing the vicinity
of the turn table 10c in a disk drive apparatus according to a
thirteenth embodiment of the present invention.
[0103] FIG. 21 is a cross-sectional side view showing the vicinity
of the turn table 110 in a disk drive apparatus according to a
fourteenth embodiment of the present invention.
[0104] FIG. 22 is a cross-sectional side view showing the vicinity
of the turn table 110 in a disk drive apparatus according to a
fifteenth embodiment of the present invention.
[0105] FIG. 23 is a cross-sectional side view showing the vicinity
of the spindle motor 2 in a disk drive apparatus according to a
sixteenth embodiment of the present invention.
[0106] FIG. 24 is a perspective view showing a conventional disk
drive apparatus.
[0107] FIG. 25 is the cross-sectional side view showing the
vicinity of the spindle motor 2 in the conventional disk drive
apparatus.
DETAILED DESCRIPTION OF THE INVENTION
[0108] First Embodiment
[0109] A disk drive apparatus according to a first embodiment of
the present invention will be described below with reference to
accompanying drawings.
[0110] FIG. 1 is a cross-sectional side view showing the vicinity
of a spindle motor 2 in the disk drive apparatus according to the
first embodiment of the present invention. FIG. 2 is a
cross-sectional plan view showing only a hollow ring member 23
provided on a clamper 16a according to the first embodiment of the
present invention. FIG. 3 is a diagram showing the case where the
center axis P2 of an outer circumferential wall 25 of the hollow
ring member 23 is displaced from the rotational center axis P0 of
the spindle motor. FIG. 4 shows measured values of the vibration
acceleration of a sub-base 6 to illustrate the effect of the disk
drive apparatus of the present invention. Here, elements
essentially identical to those in the disk drive apparatus shown in
FIGS. 24 and 25 are designated by the same reference numerals, and
descriptions of such elements are omitted.
[0111] In FIG. 1, the disk drive apparatus of the first embodiment
is constructed so that the disk 1 on the turn table 110 is clamped
in a fixed position by the clamper 16a and is driven for rotation
by the spindle motor 2. In the disk drive apparatus, reading data
recorded on the disk 1 or writing data to the disk 1 is done by
means of a head. The spindle motor 2, head driving motor, head
driving mechanism, etc. 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 the main base 8 via the insulator 7. The disk drive
apparatus body is constructed so that it can be mounted inside a
computer apparatus or the like by using a frame attached to the
main base 8.
[0112] The turn table 110 is fixed to the shaft 21 of the spindle
motor 2 and supports the clamp area 11 of the disk 1 in rotatable
fashion. A boss 14 which engages with the clamp hole 12 in the disk
1 is formed integrally with the turn table 110. The centering of
the disk 1 is achieved with the disk 1 engaging with the boss 14. A
counter yoke 15 is embedded in the upper part of the boss 14.
[0113] The clamper 16a has a center projection 17 for centering,
which engages with the positioning hole 13 formed in the turn table
110, and around which a ring-shaped magnet 18 is fixed. A flat
contacting portion 19 that contacts the disk 1 is formed on the
lower surface of the clamper 16a.
[0114] In the disk drive apparatus of the first embodiment of the
present invention, a spherical balancer 22a is formed on the
clamper 16a. As shown in FIGS. 1 and 2, the clamper 16a of the
first embodiment has the center projection (center axis) 17 formed
thereon for achieving positioning with respect to the turn table
110, and the hollow ring member 23 is provided concentrically with
the center projection 17. Inside the hollow ring member 23 houses a
plurality of spherical bodies 24 (for example, six spherical
bodies) in movable fashion. The hollow ring member 23 and the
spherical bodies 24 together constitute the spherical balancer 22a,
and the spherical balancer 22a is formed integrally with the
clamper 16a.
[0115] On the other hand, the turn table 110 has the positioning
hole 13, which is formed passing through the turn table 110, and
the positioning hole 13 is engaged with the spindle shaft 21 which
serves as the rotational center axis P0 of the spindle motor 2.
Therefore, the turn table 110 is fixed to the spindle shaft 21 so
that the turn table 110 rotates in integral fashion with the
spindle motor 2.
[0116] When the disk 1 is clamped by the clamper 16a, the disk 1 is
held on the turn table 110 with the clamp hole 12 engaging on the
boss 14, as in the case of the conventional disk drive apparatus
previously shown in FIG. 25. Then, the disk 1 is clamped and held
in position by the attractive force acting between the magnet 18
fixed to the clamper 16a and the counter yoke 15 fixed to the turn
table 110. At this time, since positioning is achieved with the
center projection (center axis) 17 formed on the clamper 16a
engaging with the positioning hole 13 formed in the turn table 110,
the hollow ring member 23 provided concentrically with the center
projection (center axis) 17 is positioned substantially coaxial
with the rotational center axis P0 of the spindle motor 2. The
clamper 16a is then driven for rotation by the spindle motor 2 in
integral fashion with the disk 1 and the turn table 110. When
removing the disk 1, the clamper 16a and the turn table 110 are
driven in directions that separate one from the other by the
driving force of a disk loading motor (not shown), thus allowing
the disk 1 to be removed.
[0117] Further, in the disk drive apparatus of the first
embodiment, the insulator (elastic member) 7 having low stiffness
is used to join the sub-base 6 to the main base 8, and the primary
resonance frequency in a direction parallel to the recording
surface of the disk 1 in the mechanical vibration of the sub-base 6
due to deformation of the insulator 7, is set lower than the
rotational frequency of the disk 1. More specifically, the
rotational frequency of the disk 1 is about 100 Hz, and the primary
resonance frequency of the vibration of the sub-base 6 is set at
about 60 Hz for both the direction in which the head is driven by
the head driving mechanism (the access direction) and the direction
at right angles to it.
[0118] Operation will be described below with reference to FIGS. 1
and 2 when a disk 1 with a large unbalance amount is rotated at 100
Hz in the thus constructed disk drive apparatus of the first
embodiment of the present invention.
[0119] First, in the disk 1, a centrifugal force (called the
imbalance force) F acts on its center of mass G1, and its acting
direction turns with the rotation of the disk 1. The insulator 7 is
deformed by the imbalance force F, and the sub-base 6 and the
entire component assembly mounted on the sub-base 6 wobble at the
rotational frequency of the disk 1. Here, the resonance frequency
(about 60 Hz) of the sub-base 6 due to the deformation of the
insulator 7 is set lower than the rotational frequency (about 100
Hz) of the disk 1. As a result, the displacing direction of the
sub-base 6 is always substantially opposite to the acting direction
of the imbalance force F. Consequently, the wobbling center axis P1
of the disk 1 rotating above the sub-base 6, the center of mass,
G1, of the disk 1 upon which the imbalance force F is acting, and
the rotational center axis P0 of the spindle motor are all arranged
substantially in a straight line, as shown in FIG. 2, with both the
wobbling center axis P1 of the disk 1 and the center of mass, G1,
of the disk 1 positioned on the same side with respect to the
rotational center axis P0 of the spindle motor.
[0120] In the above condition, since the hollow ring member 23
provided on the clamper 16a is positioned with its center aligned
with the rotational center axis P0 of the spindle motor 2, the
center of the hollow ring member 23, that is the center P2 of the
outer circumferential wall 25, coincides with the rotational center
axis P0 of the spindle motor 2, and the hollow ring member 23
wobbles about the wobbling center axis P1.
[0121] At this time, each spherical body 24 housed in the hollow
ring member 23 is acted upon by a centrifugal force q directed in
the direction joining the wobbling center axis P1 to the center of
mass of the spherical body 24. Further, since the movement of each
spherical body 24 is limited by the outer circumferential wall 25
of the hollow ring member 23, a reaction N from the outer
circumferential wall 25 is exerted on the spherical body 24. The
reaction N from the outer circumferential wall 25 is acting in the
direction toward the center P2 of the outer circumferential wall
25. As a result, a moving force R, which is the resultant force of
the centrifugal force q and reaction N, acts on each spherical body
24 in the direction of a tangent line to a circle having its center
at the center P2 of the outer circumferential wall 25 and passing
through the center of mass of the spherical body 24, and in the
direction moving away from the wobbling center axis PI. With this
moving force R, the spherical bodies 24 move along the outer
circumferential wall 25 and cluster in a position substantially
diametrically opposite the center of mass G1 of the disk 1 across
the wobbling center axis P1.
[0122] As a result, a centrifugal force Q acting on the whole
cluster of spherical bodies 24 is almost opposite in direction to
the imbalance force F acting on the center of mass G of the disk 1,
so that the imbalance force F is offset by the centrifugal force Q
and the force acting on the sub-base 6 is reduced. The vibration
generated in the sub-base 6 when the unbalanced disk 1 is rotated
is thus suppressed.
[0123] Further, in case of the hollow ring member 23 is provided on
the clamper 16a as in the first embodiment, since the space above
the disk 1 is utilized where there are few other component elements
around it, the hollow ring member 23 can be formed larger in
diameter to allow the mass per spherical body 24 or the number of
spherical bodies 24 to be increased; as a result of this is that
vibrations can be suppressed sufficiently for a disk having a
larger unbalance amount.
[0124] In the first embodiment, the primary resonance frequency in
the direction parallel to the recording surface of the disk 1 in
the mechanical vibration of the sub-base 6 due to the deformation
of the insulator 7, is set lower than the rotational frequency of
the disk 1. This is done so that the direction of the vibrational
displacement of the disk 1 due to the imbalance force becomes
substantially opposite to the acting direction of the imbalance
force.
[0125] Generally, in a mechanical vibration system consisting of a
spring and mass, a phase shift begins to occur near its resonance
frequency, between the frequency of an external force acting on the
mass and the frequency of the displacement due to the external
force. At a frequency sufficiently higher than the resonance
frequency, the phase shift is nearly 180 degrees in terms of
electrical angle, at which the acting direction of the external
force is opposite to the direction of the displacement. That is,
when the resonance frequency of the sub-base 6 is set lower than
the rotational frequency of the disk 1 and at such a frequency that
the direction of the vibrational displacement due to the imbalance
force becomes nearly opposite to the acting direction of the
imbalance force, the spherical bodies 24 cluster in a position
substantially diametrically opposite the center of mass G1 of the
disk 1, and the acting direction of the centrifugal force Q acting
on the spherical bodies 24 becomes substantially opposite to the
acting direction of the imbalance force, as already mentioned.
Accordingly, it is desirable that the resonance frequency of the
sub-base 6 be set by considering the direction of the vibrational
displacement due to the imbalance force of the rotational frequency
of the disk 1.
[0126] Next, we will discuss how the resonance frequency of the
sub-base 6 is set in a disk drive apparatus designed to record or
reproduce with constant linear velocity, that is, by varying the
rotational frequency between the inner and outer circumferences of
a disk, or in a disk drive apparatus designed to record or
reproduce with constant angular velocity but to rotate disks not at
a single rotational frequency but at a plurality of rotational
frequencies.
[0127] Vibration and noise due to the unbalance of the disk 1
increase with increasing rotational frequency of the disk 1.
Therefore, a sufficient effect cannot be obtained by the spherical
balancer 22a in the first embodiment unless the resonance frequency
of the sub-base 6 is set at least lower than the maximum rotational
frequency of the disk 1.
[0128] Further, the resonance frequency of the sub-base 6 need not
be set unnecessarily lower than the rotational frequency when
vibration is small and does not affect the operation of the disk
drive apparatus or when noise is sufficiently suppressed, but it is
desirable that the resonance frequency be set sufficiently lower
than the rotational frequency (for example, 100 Hz) at which the
vibration and noise due to the imbalance force begin to cause
problems.
[0129] In the first embodiment of the present invention, the
direction of the vibrational displacement of the disk 1 due to the
imbalance force is set nearly opposite to the acting direction of
the imbalance force by setting the primary resonance frequency of
the sub-base 6 due to the deformation of the insulator (elastic
member) 7 lower than the rotational frequency of the disk 1, as
previously described. Theoretically, the direction of the
vibrational displacement of the disk 1 due to the imbalance force
can be set nearly opposite to the acting direction of the imbalance
force by setting the primary resonance frequency (critical speed)
of the flexural vibration caused in the spindle shaft by the
imbalance force lower than the rotational frequency of the disk 1.
However, if the primary resonance frequency of the flexural
vibration of the spindle shaft is to be set lower than the
rotational frequency (for example, 100 Hz) at which the vibration
and noise due to the imbalance force begin to cause problems, the
stiffness of the spindle shaft will have to be set lower than the
level required in the disk drive apparatus, and it will pose a
problem if the disk drive apparatus is to be driven for rotation by
such a spindle shaft. When a spindle shaft with low stiffness is
used, trouble will occur, for example, with the torsional vibration
generated in the spindle shaft exciting the resonance of the disk
1.
[0130] On the other hand, in the first embodiment of the present
invention, since the primary resonance frequency of the sub-base 6
due to the deformation of the insulator (elastic member) 7 is set
lower than the rotational frequency of the disk 1, as previously
mentioned, the direction of the vibrational displacement of the
disk 1 due to the imbalance force can be set nearly opposite to the
acting direction of the imbalance force. Accordingly, the vibration
suppressing effect of the spherical balancer 22a can be fully
displayed without reducing the stiffiess of the spindle shaft
21.
[0131] In the first embodiment of the present invention,
positioning is achieved by engaging the center projection (center
axis) 17 provided on the clamper 16a with the hole in which the
spindle shaft 21 of the spindle motor 2 is fitted, that is, the
same hole as the positioning hole 13. As a result, in the disk
drive apparatus of the first embodiment, the center of the hollow
ring member 23 formed concentrically with the center projection
(center axis) of the clamper 16a coincides with the rotational
center axis P0 of the spindle motor 2; as a result, the spherical
bodies 24 cluster in the position diametrically opposite the center
of mass GI of the disk 1, and the vibration suppressing effect can
thus be increased.
[0132] As in the conventional disk drive apparatus previously shown
in FIG. 24, if the hole engaged with the clamper 116 is different
from the hole in which the spindle shaft 21 is rigidly supported,
or if the construction is such that the positioning is achieved by
engaging a tapered portion provided on the turntable 110 with a
tapered portion provided on the clamper 116, the positional
displacement between the center of the hollow ring member and the
rotational center axis P0 of the spindle motor 2 may further
increase due to the effects of the displacement between the axes of
the holes, dimensional errors of the tapered portions, etc. If the
hollow ring member 23 of the present embodiment is provided on the
clamper of such a disk drive apparatus, the following problem will
arise.
[0133] Referring to FIGS. 2 and 3, operation will be described when
the center of the hollow ring member 23, that is, the center P2 of
the outer circumferential wall 25, is displaced from the rotational
center axis P0 of the spindle motor 2.
[0134] FIG. 2 showed the case where the center axis P2 of the outer
circumferential wall 25 coincides with the rotational center axis
P0 of the spindle motor; on the other hand, FIG. 3 shows the case
where there is a displacement between their positions. In FIG. 2,
wobbling motion is performed with the center P2 of the outer
circumferential wall 25 maintained at the same position as the
rotational center axis P0 of the spindle motor 2, the center P2 of
the outer circumferential wall 25 wobbling about the center axis P1
with a radius X1.
[0135] In FIG. 3, the center P2 of the outer circumferential wall
25 is located at a position displaced by X from the rotational
center axis P0 of the spindle motor 2, so that the center P2 of the
outer circumferential wall 25 wobbles with a radius X2. In this
condition, when the mass of the spherical body 24 remains the same
the moving force R acting on each spherical body 24 increases as
the angle between the direction of the centrifugal force q acting
on the spherical body 24 and the direction of the reaction N from
the outer circumferential wall 25 increases, and the angle k
increases as the rotational radius X2 of the wobbling motion
increases. Quantitatively, the magnitude of the moving force R is
proportional to the product of the rotational radius X2 of the
wobbling motion and the rotational frequency. Therefore, the moving
force R is reduced when the rotational radius of the wobbling
motion is reduced with the center axis P2 of the outer
circumferential wall 25 displaced by X from the rotational center
axis P0 of the spindle motor, as shown in FIG. 3. When the moving
force R is reduced, the movement of the spherical bodies 24 is
obstructed because of the frictional resistance and rolling
resistance along the outer circumferential wall 25 and the bottom
surface of the hollow ring member 23, leading to a phenomenon in
which the spherical bodies 24 do not cluster in the position
diametrically opposite the center of mass, G1, of the disk 1. As
described above, when the positional displacement between the
center of the hollow ring member 23 and the rotational center axis
P0 of the spindle motor 2 is large, the vibration suppressing
effect of the spherical bodies 24 is reduced.
[0136] To address this problem, the first embodiment of the present
invention is constructed so that the positioning of the clamper 16a
is achieved by engaging the center projection (center axis) 17
provided on the clamper 16a with the hole in which the spindle
shaft 21 of the spindle motor 2 is fitted, that is, the same hole
as the positioning hole 13. This construction, therefore,
substantially prevents a positional displacement from occurring
between the center of the hollow ring member 23 formed
concentrically with the center projection (center axis) 17 of the
clamper 16a and the rotational center axis P0 of the spindle motor
2. Accordingly, in the disk drive apparatus of the first
embodiment, the spherical bodies 24 cluster in the position
diametrically opposite the center of mass G1 of the disk 1 without
fail, thus enhancing the vibration suppressing effect.
[0137] FIG. 4 shows the results of an experiment in which the
effect of the disk drive apparatus of the first embodiment was
examined using a disk 1 having an unbalance amount of about 1
gcm.
[0138] In this experiment, the vibrational acceleration of the
sub-base 6 was actually measured when the disk 1 was rotated at
about 100 Hz. Part (a) of FIG. 4 shows the case of the conventional
disk drive apparatus not equipped with a spherical balancer. As
shown in part (a) of FIG. 4, in the conventional disk drive
apparatus, the sub-base 6 is vibrating with a maximum acceleration
of about 8G. Part (b) of FIG. 4 shows the case of the disk drive
apparatus according to the first embodiment of the present
invention; the vibrational acceleration is reduced to about 3G.
[0139] In this way, in the disk drive apparatus of the first
embodiment, since the vibrational acceleration is reduced, the side
pressure being applied to the bearing of the spindle motor 2 by the
imbalance force F is reduced, solving the problems of increased
bearing damaging torque, damage to the bearing, and shortened
bearing life.
[0140] As described above, according to the construction of the
disk drive apparatus of the first embodiment, the vibration of the
sub-base 6 due to the unbalance of the loaded disk 1 can be
suppressed reliably without having to increase the stiffness of the
insulator 7. Accordingly, the disk drive apparatus of the first
embodiment is capable of stable recording or reproducing even when
a greatly unbalanced disk 1 is rotated at high speed, and a disk
drive apparatus capable of high speed rotation can be achieved
without degrading its anti-vibration, anti-shock
characteristics.
[0141] <<Second Embodiment>>
[0142] Next, a disk drive apparatus according to a second
embodiment of the present invention will be described with
reference to drawing. FIG. 5 is a cross-sectional side view showing
the vicinity of the spindle motor 2 in the disk drive apparatus
according to the second embodiment of the present invention. FIG. 6
is a cross-sectional plan view showing only a hollow ring member 23
provided on a clamper 16a in the disk drive apparatus of the second
embodiment. Here, elements essentially identical to those in the
disk drive apparatus of the foregoing first embodiment shown in
FIG. 1 or to those in the disk drive apparatus shown in FIGS. 24
and 25 are designated by the same reference numerals, and
descriptions of such elements are omitted.
[0143] In the disk drive apparatus of the second embodiment of the
present invention, the spherical bodies 24 in the hollow ring
member 23 provided on the clamper 16a in the foregoing first
embodiment are replaced by a liquid 26 which is sealed therein to
form a liquid balancer 27. In other respects, the construction is
the same as that of the foregoing first embodiment. Water, oil, or
even a fluid with fine particles suspended therein, is used as the
liquid.
[0144] In the thus constructed disk drive apparatus of the second
embodiment, when a disk 1 with a large unbalance amount is rotated
at 100 Hz, the sub-base 6 and the entire component assembly mounted
on the sub-base 6 wobble at the rotational frequency of the disk 1
because of the imbalance force F acting on the center of mass, G1,
of the disk 1, as in the case of the first embodiment. In the disk
drive apparatus of the second embodiment, the resonance frequency
of the sub-base 6 (about 60 Hz) due to the deformation of the
insulator 7 is set lower than the rotational frequency of the disk
1 (100 Hz), that is, the vibration frequency due to the imbalance
force F. As a result, the center axis P1 about which the disk 1
wobbles is located between the center of mass G1 of the disk 1,
upon which the imbalance force F is acting, and the rotational
center axis P0 of the spindle motor. In this condition, the liquid
26 sealed in the hollow ring member 23 provided on the clamper 16a
forms a free water surface 28 of radius S with its center at the
wobbling center axis P1 because of the centrifugal force Q acting
radially from the wobbling center axis P1 toward the outer
circumferential wall 25. Thus, the liquid 26 is concentrated in a
position diametrically opposite the center of mass G1 of the disk.
Accordingly, as in the foregoing first embodiment which used the
spherical bodies 24, the imbalance force F acting on the center of
mass G1 of the disk 1 is offset by the centrifugal force Q acting
on the liquid 26 concentrated in the position diametrically
opposite the center of mass G1 of the disk. As a result, in the
disk drive apparatus of the second embodiment, the vibration of the
sub-base 6 due to the unbalance of the disk 1 is reliably
suppressed.
[0145] In the second embodiment, the liquid 26 is used instead of
the spherical bodies 24 that served as a balancer in the first
embodiment; when the liquid 26 used in the second embodiment is
compared with the spherical bodies 24 used in the first embodiment
assuming that the spherical bodies 24 are steel balls, the
centrifugal force Q acting on the liquid 26 is smaller since,
generally, a liquid has a smaller specific gravity. In the disk
drive apparatus of the second embodiment, therefore, a liquid of a
large volume is required if the imbalance force F is to be offset
completely. Accordingly, when using a liquid, it is desirable that
the balancer be constructed so that the largest possible
centrifugal force Q can be generated utilizing the space allowed
for the balancer within the apparatus.
[0146] The magnitude of the centrifugal force Q acting on the
liquid 26 increases as the radius of the outer circumferential wall
25 of the hollow ring member 23 and the volume of the liquid 26
sealed therein increase; when both are limited, the magnitude is
determined by the specific gravity of the liquid 26 and the radius
S of the free water surface 28. The radius S of the free water
surface 28 increases with increasing distance between the center of
the hollow ring member 23 and the wobbling center axis P1 of the
disk 1, that is, with increasing rotational radius X1 of the
wobbling motion. Therefore, if the center P2 of the hollow ring
member 23 is displaced by X from the rotational center axis P0 of
the spindle motor, as shown in FIG. 3, the radius S of the free
water surface 28 decreases correspondingly.
[0147] However, the disk drive apparatus of the second embodiment,
as in the foregoing first embodiment, employs the construction such
that the positioning is achieved with the center projection (center
axis) 17 provided on the clamper 16a engaging with the hole in
which the spindle shaft 21 of the spindle motor 2 is fitted, that
is, the same hole as the positioning hole 13, to substantially
eliminate the positional displacement between the center P2 of the
hollow ring member 23 and the rotational center axis P0 of the
spindle motor 2. With this construction, the disk drive apparatus
of the second embodiment prevents the rotational radius X1 of the
wobbling motion from decreasing, and allows the radius S of the
free water surface 28 to be increased, making it possible to
generate a larger centrifugal force Q within a limited volume.
[0148] Further, in the second embodiment, the liquid 26 is used in
place of the spherical bodies 24 used as a balancer in the first
embodiment; in the case of a liquid, since there are fewer factors
that impede its movement, the balancer can be concentrated reliably
in a position opposite the disk mass center G1, so that a stable
effect can be obtained with the disk drive apparatus of the second
embodiment. More specifically, when the unbalance amount is
relatively small, or when a performance of increased stability is
required, the balancer using a liquid as in the second embodiment
achieves a greater effect.
[0149] The second embodiment has dealt with an example in which a
liquid is used as the balancer, but it will be appreciated that a
similar effect to that of the second embodiment can be obtained if
a powder or a mixed fluid of liquid with spherical bodies is
used.
[0150] <<Third Embodiment>>
[0151] Next, a disk drive apparatus according to a third embodiment
of the present invention will be described with reference to
drawing. FIG. 7 is a cross-sectional side view showing the vicinity
of the spindle motor 2 in the disk drive apparatus according to the
third embodiment of the present invention. FIG. 8 is a
cross-sectional plan view showing only hollow ring members 23a and
23b provided on a clamper 16a in the disk drive apparatus of the
third embodiment. Here, elements essentially identical to those in
the disk drive apparatus of the foregoing first and second
embodiments or to those in the disk drive apparatus shown in FIGS.
24 and 25 are designated by the same reference numerals, and
descriptions of such elements are omitted.
[0152] In the disk drive apparatus of the third embodiment of the
present invention, the two hollow ring members 23a and 23b are
provided concentrically with the center projection (center axis) 17
formed on the clamper 16b for positioning with respect to the turn
table 110. Inside the first hollow ring member 23a located on the
inner circumferential side are housed a plurality of spherical
bodies 24 in movable fashion, while the second hollow ring portion
23b located on the outer circumferential side contains a liquid
26.
[0153] Thus the spherical bodies 24 in the first hollow ring member
23a and the liquid 26 in the second hollow ring member 23b together
constitute a balancer 29. This balancer 29 is formed integrally
with the clamper 16b. In other respects, the construction is the
same as that of the first embodiment, and the description thereof
is therefore omitted.
[0154] In the thus constructed disk drive apparatus of the third
embodiment, when a disk 1 with a large unbalance amount is rotated
at 100 Hz, the insulator 7 deforms due to the imbalance force F
acting on the center of mass G1 of the disk 1, and the sub-base 6
and the entire component assembly mounted on the sub-base 6 wobble
at the rotational frequency of the disk 1, as in the case of the
first embodiment.
[0155] In the third embodiment, the resonance frequency of the
sub-base 6 (about 60 Hz) due to the deformation of the insulator 7
is set lower than the rotational frequency of the disk 1 (about 100
Hz), so that the sub-base 6 is always deformed in a direction
substantially opposite to the acting direction of the imbalance
force F. As a result, the wobbling center axis P1 of the disk 1
rotating above the sub-base 6 is located between the center of
mass, G1 of the disk 1, upon which the imbalance force F is acting,
and the rotational center axis P0 of the spindle motor, as shown in
FIG. 8.
[0156] In the disk drive apparatus of the third embodiment, the
first hollow ring member 23a and second hollow ring member 23b
provided on the clamper 16b are formed concentrically, and their
center P2 is positioned substantially concentric with the
rotational center axis P0 of the spindle motor 2. As a result, the
center P2 of the outer circumferential wall 25a of the first hollow
ring member 23a and the outer circumferential wall 25b of the
second hollow ring member 23b coincides with the rotational center
axis P0 of the spindle motor 2, and wobbles about the wobbling
center axis P1.
[0157] The plurality of spherical bodies 24 contained in the first
hollow ring 23a move along the outer circumferential wall 25a due
to the moving force R which is the resultant force of the
centrifugal force qa and the reaction from the outer
circumferential wall 25a, and cluster toward the position
substantially diametrically opposite the center of mass G1 of the
disk 1 across the wobbling center axis P1, thus generating a
centrifugal force Qa, as in the previously described first
embodiment.
[0158] On the other hand, the liquid 26 sealed in the second hollow
ring member 23b forms a free water surface 28 of radius S with its
center at the wobbling center axis P1 by the action of a
centrifugal force Qb, as in the foregoing second embodiment.
Accordingly, the liquid 26 is concentrated in the position
substantially diametrically opposite the disk mass center G1.
[0159] As a result, the imbalance force F acting on the center of
mass G of disk 1 is offset by the centrifugal forces Qa and Qb
acting on the plurality of spherical bodies 24 and the liquid 26,
respectively, gathered in the position substantially diametrically
opposite the center of mass G1 of the disk 1, thus suppressing the
vibration of the sub-base 6 that occurs when the unbalanced disk 1
is rotated.
[0160] When both the first hollow ring member 23a with the
spherical bodies 24 contained therein and the second hollow ring
member 23b with the liquid 26 sealed therein are provided on the
clamper 16b, as in the above third embodiment, the respective
shortcomings of the spherical balancer and liquid balancer are
compensated for and a better vibration suppressing effect can be
obtained.
[0161] Next, the complementary effect of the spherical balancer and
liquid balancer will be described with reference to FIGS. 8 and 9.
FIG. 9 illustrates the positions of the spherical bodies 24 and
liquid 26 when a well-balanced, ideal disk is rotated.
[0162] When a greatly unbalanced disk 1 is rotated, the spherical
bodies 24 and the liquid 26 are concentrated in the position
substantially diametrically opposite the disk mass center G1, and
the imbalance force F is offset primarily by the centrifugal force
Qa acting on the spherical bodies 24 having a larger specific
gravity.
[0163] On the other hand, when a well-balanced, ideal disk 1 is
rotated, the spherical bodies 24 and the liquid 26 are unevenly
distributed in position. With this uneven positional distribution,
there arises the possibility that the clamper 16b may be thrown out
of balance by the spherical bodies 24 or the liquid 26 itself.
Accordingly, it is desirable that the plurality of spherical bodies
24 be moved to positions counterbalancing each other and the liquid
26 be evenly distributed, as shown in part (a) of FIG. 9.
[0164] However, since the spherical bodies 24 are subjected to
frictional resistance and rolling resistance along the outer
circumferential wall 25a and bottom surface of the first hollow
ring member 23a, the movement of the spherical bodies 24 is impeded
if the moving force R acting on the spherical bodies 24 is smaller
than these resistive forces. As previously described in the
explanation of the first embodiment, the moving force R acting on
the spherical bodies 24 is proportional to the radius X1 of the
wobbling motion shown in FIG. 3, and the radius X1 of the wobbling
motion increases as the imbalance force F increases. Accordingly,
in case of a disk 1 almost free from mass imbalance, the spherical
bodies 24 cannot be moved to the positions counterbalancing each
other as shown in part (a) of FIG. 9, unless the amount of
unbalance due to the spherical bodies 24 themselves becomes greater
than a certain level, for example, with the spherical bodies 24
temporarily gathering in one position and causing an unbalanced
condition. By contrast, the liquid 26 sealed in the second hollow
ring member 23b moves without fail even when the unbalance is
small, since there are few factors impeding its movement.
Accordingly, as shown in part (b) of FIG. 9, even when the
spherical bodies 24 cannot be moved to the desired positions, the
liquid 26 is gathered in a position counterbalancing the imbalance
in the spherical bodies 24 themselves, and the vibration can thus
be suppressed.
[0165] As described above, according to the construction of the
third embodiment of the present invention, the vibration of the
sub-base 6 can be suppressed regardless of whether the mass of the
disk 1 rotating at high speed is greatly unbalanced or well
balanced; therefore, the disk drive apparatus of the third
embodiment ensures stable recording or playback on any disk 1
without generating noise, and a disk drive apparatus capable of
higher speed rotation can thus be achieved.
[0166] <<Fourth Embodiment>>
[0167] Next, a disk drive apparatus according to a fourth
embodiment of the present invention will be described with
reference to drawing. FIG. 10 is a cross-sectional side view
showing the vicinity of the spindle motor 2 in the disk drive
apparatus according to the fourth embodiment of the present
invention. Here, elements essentially identical to those in the
disk drive apparatus of the first and second embodiments or to
those in the disk drive apparatus shown in FIGS. 24 and 25 are
designated by the same reference numerals, and descriptions of such
elements are omitted.
[0168] In the disk drive apparatus of the fourth embodiment of the
present invention, the spindle shaft 21 is fitted into the
positioning hole 13 formed in the turn table 110 and is passed
through the positioning hole 13. The spindle shaft 21 passed
through the positioning hole 13 in the turn table 110 is fitted
into the center hole 117 formed in the center of the clamper 16c,
and the clamper 16c is positioned in place with the spindle shaft
21 passing through it.
[0169] The hollow ring member 23 is provided concentrically with
the center hole 117 in the clamper 16c, and inside the hollow ring
member 23 are housed a plurality of spherical bodies 24. Thus the
hollow ring member 23 and the spherical bodies 24 together
constitute a spherical balancer 22b, and the spherical balancer 22b
is formed integrally with the clamper 16c. In other respects, the
construction is the same as that of the previously described first
embodiment.
[0170] In the thus constructed disk drive apparatus of the fourth
embodiment, when a disk 1 having a large unbalance amount is
rotated at 100 Hz, the wobbling center axis P1 of the disk 1
rotating on the sub-base 6 is located between the center of mass G1
of the disk 1, upon which the imbalance force F is acting, and the
rotational center axis P0 of the spindle motor, as in the case of
the first embodiment shown in FIG. 2.
[0171] As shown in FIG. 10, the hollow ring member 23 provided on
the clamper 16c in the disk drive apparatus of the fourth
embodiment is formed concentrically with the center hole 117.
Further, the center hole 117 is formed so as to directly fit onto
the spindle shaft 21 which is the rotational center axis of the
spindle motor 2. Accordingly, the displacement X of the center P2
of the outer circumferential wall 25 of the hollow ring member 23
with respect to the rotational center axis P0 of the spindle motor
2 is setted to substantial zero, as in the first embodiment
previously shown in FIG. 3. This serves to avoid the problem that
the vibration suppressing effect of the spherical bodies 24 is
reduced because of the positional displacement between the center
P2 of the hollow ring member 23 and the rotational center axis P0
of the spindle motor 2, as previously described in connection with
the first embodiment.
[0172] As described above, with the construction of the fourth
embodiment of the present invention, the vibration suppressing
effect of the balancer using the spherical bodies 24 can be further
enhanced.
[0173] <<Fifth Embodiment>>
[0174] Next, a disk drive apparatus according to a fifth embodiment
of the present invention will be described with reference to
drawing. FIG. 11 is a cross-sectional plan view showing the hollow
ring member 23 provided on the clamper in the disk drive apparatus
of the fifth embodiment. Here, elements essentially identical to
those in the disk drive apparatus of the first and second
embodiments or to those in the disk drive apparatus shown in FIGS.
24 and 25 are designated by the same reference numerals, and
descriptions of such elements are omitted.
[0175] The disk drive apparatus of the fifth embodiment of the
present invention is aimed at reducing the magnitude of the noise
occurring from the balancer itself, and as in the first embodiment
previously shown in FIG. 1, the spherical balancer 22c is formed
integrally with the clamper.
[0176] As shown in FIG. 11, in the disk drive apparatus of the
fifth embodiment, metal spherical bodies 24c and plastic spherical
bodies 24d arranged in alternating fashion are housed inside the
hollow ring member 23. In other respects, the construction is the
same as that of the previously described first embodiment.
[0177] In the thus constructed disk drive apparatus of the fifth
embodiment, when a disk 1 with a large unbalance amount is rotated
at 100 Hz, the metal spherical bodies 24c and plastic spherical
bodies 24d are concentrated in the position substantially
diametrically opposite the disk mass center G1 by the moving force
R acting on the respective spherical bodies, as in the previously
described first embodiment. Since the resultant force Q of the
centrifugal forces acting on the respective spherical bodies works
to offset the imbalance force F acting on the disk mass center G1,
the vibration of the sub-base 6 in the disk drive apparatus of the
fifth embodiment is suppressed.
[0178] Next, a description will be given of the movements of the
spherical bodies in the spherical balancer when the disk 1 is in a
stopped condition, or when the rotational frequency is low during
acceleration where the disk 1 is accelerated from the stopped
condition toward a target rotational frequency or during
deceleration where the disk 1 is decelerated for stopping.
[0179] When the disk 1 is in a stopped condition, no centrifugal
forces are acting on the spherical bodies as a matter of course,
and when the rotational frequency is low, the centrifugal forces
acting on the spherical bodies are small; as a result, a situation
can occur where the spherical bodies are not pressed against the
outer circumferential wall 25 of the hollow ring member 23.
Accordingly, when vibration is applied from the outside during
transportation of the disk drive apparatus, or when the disk 1 is
in an early stage of the acceleration process or at the end of the
deceleration process, the spherical bodies move freely inside the
hollow ring member 23, and hit against each other or against the
inner wall surfaces of the hollow ring member 23. As a result, if
all the spherical bodies are made of a hard material such as metal,
colliding noise will occur in the above conditions, and the
magnitude of the noise may increase to an undesirable level.
[0180] In the fifth embodiment of the present invention, therefore,
the metal spherical bodies 24c arranged alternately between the
plastic spherical bodies 24d having a lower hardness are housed
inside the hollow ring member 23, as shown in FIG. 11, thus at
least avoiding the possibility of the hard metal spherical bodies
24c directly hitting against each other. With this construction,
the disk drive apparatus of the fifth embodiment can reduce the
magnitude of the noise occurring when the disk 1 is in a stopped
condition or is in an early stage of the acceleration process or at
the end of the deceleration process.
[0181] Here, the plastic spherical bodies 24d may be formed
entirely from a plastic material, but the same effect can be
obtained if they are formed from metal spherical bodies coated with
a plastic material or vibration isolating rubber.
[0182] As described above, with the construction of the fifth
embodiment of the present invention, a disk drive apparatus can be
achieved that ensures stable recording or reproducing playback even
when a disk with a greatly unbalanced mass is rotated at high
speed, and that does not generate undesirable noise not only during
high speed rotation but also during the acceleration or
deceleration of disk rotation, or even during transportation of the
apparatus.
[0183] <<Sixth Embodiment>>
[0184] Next, a disk drive apparatus according to a sixth embodiment
of the present invention will be described with reference to
drawing. FIG. 12 is a cross-sectional side view showing the
vicinity of the spindle motor 2 in the disk drive apparatus
according to the sixth embodiment of the present invention. Here,
elements essentially identical to those in the disk drive apparatus
of the first and second embodiments or to those in the disk drive
apparatus shown in FIGS. 24 and 25 are designated by the same
reference numerals, and descriptions of such elements are
omitted.
[0185] In the disk drive apparatus of the sixth embodiment of the
present invention, the hollow ring member 23 which was provided on
the clamper 16 in the first embodiment is provided on the turn
table 10. Inside the hollow ring member 23 in the sixth embodiment
are housed a plurality of spherical bodies 24 in movable fashion.
The clamper 116 used in the sixth embodiment is the same as that
used in the disk drive apparatus shown in FIGS. 24 and 25; in other
respects, the construction of the sixth embodiment is the same as
that of the previously described first embodiment.
[0186] In the disk drive apparatus of the sixth embodiment, the
plurality of spherical bodies 24 are contained in movable fashion
inside the hollow ring member 23. Accordingly, since the hollow
ring member 23 is provided on the turn table 10 which is always
constructed in integral fashion with the shaft 21 of the spindle
motor 2, it is easy to form the center axis of the hollow ring
member 23 so as to be coaxial with the spindle motor rotational
center axis P0 of the hollow ring member 23. As a result, the
displacement between the center axis P2 of the outer
circumferential wall 25 of the hollow ring member 23 and the
rotational center axis P0 of the spindle motor can be virtually
eliminated, and the effect of the ball balancer 22 can be obtained
stably and consistently. In the sixth embodiment, the plurality of
spherical bodies 24 are housed inside the hollow ring member 23
provided on the turn table 10, but it will be appreciated that the
same effect can be obtained if the liquid 26 is sealed therein
instead of the spherical bodies 24.
[0187] <<Seventh Embodiment>>
[0188] Next, a disk drive apparatus according to a seventh
embodiment of the present invention will be described with
reference to drawing. Parts (a) and (b) of FIG. 13 are
cross-sectional side views showing the vicinity of the spindle
motor 2 in the disk drive apparatus of the seventh embodiment. The
part (a) of FIG. 13 shows the condition in which the disk 1 is
stationary or is rotating at slow speed, while the part (b) of FIG.
13 shows the condition in which the disk 1 is rotating at high
speed. Here, elements essentially identical to those in the disk
drive apparatus of the first and second embodiments or to those in
the disk drive apparatus shown in FIGS. 24 and 25 are designated by
the same reference numerals, and descriptions of such elements are
omitted.
[0189] The seventh embodiment of the present invention concerns a
disk drive apparatus that is able to reduce the magnitude of the
noise occurring from the balancer itself. As shown in the parts (a)
and (b) of FIG. 13, the hollow ring member 23c is provided on the
turn table 10a, and a plurality of magnetic spherical bodies 24e
are housed inside the hollow ring member 23c. The spherical
balancer 22d consisting of the hollow ring member 23c and the
magnetic spherical bodies 24e is formed integrally with the turn
table 10a.
[0190] In the disk drive apparatus of the seventh embodiment, a
ring-shaped magnet 30 is mounted on the inner circumferential side
of the hollow ring member 23c. Further, the clamper 116 used in the
disk drive apparatus of the seventh embodiment is the same as that
used in the conventional disk drive apparatus; in other respects,
the construction is the same as that of the previously described
first embodiment.
[0191] In the disk drive apparatus of the seventh embodiment, since
the plurality of magnetic spherical bodies 24e are contained inside
the hollow ring member 23c, and the ring-shaped magnet 30 is
mounted on the inner circumferential side of the hollow ring member
23c, the magnetic spherical bodies 24e are acted upon by the
attractive force from the magnet 30 so that the magnetic spherical
bodies 24e are urged at all times in such a direction as to contact
the inner circumferential wall 31 of the hollow ring member 23c. As
a result, when the disk 1 is stationary, or when the rotational
frequency of the disk 1 is low in an early stage of the
acceleration process or at the end of the deceleration process, and
the centrifugal force acting on the magnetic spherical bodies 24e
is small, the magnetic spherical bodies 24e are made to adhere to
the inner circumferential wall 31 of the hollow ring member 23c by
the attractive force of the magnet 30, as shown in the part (a) of
FIG. 13.
[0192] Accordingly, when vibration is applied from the outside
during transportation of the disk drive apparatus, or when the disk
1 is in an early stage of the acceleration process or at the end of
the deceleration process, as described in the explanation of the
fifth embodiment, the spherical bodies are prevented from hitting
against each other or against the inner wall surfaces of the hollow
ring member 23c, and generation of undesirable noise can thus be
avoided.
[0193] On the other hand, when the rotational frequency of the disk
1 increases to the point where the vibration caused by the
unbalance of the disk 1 becomes undesirably large, the magnetic
spherical bodies 24e are pressed against the outer circumferential
wall 25c of the hollow ring member 23c by its centrifugal force, as
shown in the part (b) of FIG. 13.
[0194] For example, when the disk 1 is accelerated for rotation,
and the rotational frequency of the disk 1 increases to the point
where the centrifugal force acting on the magnetic spherical bodies
24e becomes greater than the attractive force of the magnet 30, the
magnetic spherical bodies 24e adhering to the inner circumferential
wall 31 are thrown toward the outer circumferential wall 25c.
[0195] When fs denotes the rotational frequency that causes the
magnetic spherical bodies 24e to be thrown toward the outer
circumferential wall 25c, fh denotes the rotational frequency that
generates a centrifugal force sufficient to press and hold the
magnetic spherical bodies 24e against the outer circumferential
wall 25c, and fn denotes the rotational frequency where the
vibration caused by the unbalance of the disk 1 becomes undesirably
large, it is desirable that the relation between them be set as
fh<fs<fn. That is, it is desirable that fs be set
sufficiently higher than fh so that the magnetic spherical bodies
24e can be attracted and held securely even if vibration or shock
is applied from the outside when the rotational frequency of the
disk 1 is lower than fh, and it is preferable that the magnitude of
the attractive force of the magnet 30 is set so that fs is lower
than fn and the vibration suppressing effect of the spherical
balancer 22c can be displayed.
[0196] Further, in the disk drive apparatus of the seventh
embodiment, since the hollow ring member 23c is provided on the
turn table 10a fixed to the spindle shaft 21 of the spindle motor
2, it is easy to form the center axis of the hollow ring member 23c
to be coaxial with the spindle motor rotational center axis P0 of
the hollow ring member 23c.
[0197] Accordingly, the displacement X between the center P2 of the
outer circumferential wall 25 and the rotational center axis P0 of
the spindle motor, such as previously shown in FIG. 3, is almost
eliminated; this serves to avoid the problem that the vibration
suppressing effect of the spherical bodies 24 is reduced because of
the positional displacement between the center of the hollow ring
member 23 and the rotational center axis P0 of the spindle motor 2,
as previously described in connection with the first
embodiment.
[0198] Furthermore, if magnetic steel balls having a large specific
gravity are used as the spherical bodies housed inside the hollow
ring member 23c, it is possible to further enhance the effect of
suppressing the vibration caused by the imbalance force.
[0199] As described above, with the construction of the seventh
embodiment of the present invention, a disk drive apparatus can be
achieved that ensures stable recording or reproducing even when a
disk with a greatly unbalanced mass is rotated at high speed, and
that does not generate undesirable noise not only during high speed
rotation but also during the acceleration or deceleration of disk
rotation, or even during transportation of the apparatus.
[0200] <<Eighth Embodiment>>
[0201] Next, a disk drive apparatus according to an eighth
embodiment of the present invention will be described with
reference to drawing. FIG. 14 is a cross-sectional side view
showing the vicinity of the spindle motor 2 in the disk drive
apparatus of the eighth embodiment. Here, elements essentially
identical to those in the disk drive apparatus of the foregoing
first and second embodiments or to those in the disk drive
apparatus shown in FIGS. 24 and 25 are designated by the same
reference numerals, and descriptions of such elements are
omitted.
[0202] In the disk drive apparatus of the eighth embodiment of the
present invention, the hollow ring member 23c is provided on the
turn table 10b, as shown in FIG. 14, and a plurality of magnetic
spherical bodies 24e are contained inside the hollow ring member
23c; the spherical balancer 22d consisting of the hollow ring
member 23c and the magnetic spherical bodies 24e is formed
integrally with the turn table 10b.
[0203] In the disk drive apparatus of the eighth embodiment, the
ring-shaped magnet 30 is mounted on the outer circumferential side
of the hollow ring member 23c. In other respects, the construction
is the same as that of the foregoing seventh embodiment.
[0204] In the thus constructed eighth embodiment, as in the
foregoing seventh embodiment, the magnetic spherical bodies 24e are
acted upon by the attractive force from the magnet 30 so that the
magnetic spherical bodies 24e are urged at all times in such a
direction as to contact the outer circumferential wall 25c of the
hollow ring member 23c. As a result, when the disk 1 is stationary,
or when the rotational frequency of the disk 1 is low during the
starting of disk rotation or at the end of the deceleration
process, and the centrifugal force acting on the magnetic spherical
bodies 24e is small, the magnetic spherical bodies 24e are made to
stick to the outer circumferential wall 25c of the hollow ring
member 23c by the attractive force of the magnet 30. Accordingly,
as in the foregoing seventh embodiment, when vibration is applied
from the outside during transportation of the disk drive apparatus,
or when the disk 1 is in an early stage of the acceleration process
or at the end of the deceleration process, the spherical bodies are
prevented from hitting against each other or against the inner wall
surfaces of the hollow ring member 23c, and generation of
undesirable noise can thus be avoided.
[0205] In the disk drive apparatus of the eighth embodiment, unlike
the foregoing seventh embodiment, the magnetic spherical bodies 24e
are kept contacting and adhering to the outer circumferential wall
25c regardless of the rotational frequency of the disk 1 and even
when the disk 1 is stationary. Accordingly, in the disk drive
apparatus of the eighth embodiment, if the magnet 30 is magnetized
so that the attractive force of the magnet 30 acting on the
magnetic spherical bodies 24e does not become excessive but becomes
uniform along the entire circumference of the outer circumferential
wall 25c, the attractive force of the magnet 30 does not prevent
the magnetic spherical bodies 24e from moving to the position
opposite the disk mass center G1, and a sufficient vibration
suppressing effect can be obtained. Preferably, the magnet 30 is
single-pole magnetized, for example, in the direction of the center
axis of the outer circumferential wall 25c.
[0206] As described above, with the construction of the eighth
embodiment of the present invention, a disk drive apparatus capable
of high speed rotation can be achieved that ensures stable
recording or reproducing even when a disk with a greatly unbalanced
mass is rotated at high speed, and that does not generate
undesirable noise not only during high speed rotation but also
during the acceleration or deceleration of disk rotation, or even
during transportation of the apparatus.
[0207] <<Ninth Embodiment>>
[0208] Next, a disk drive apparatus according to a ninth embodiment
of the present invention will be described with reference to
drawing. FIG. 15 is a cross-sectional side view showing the
vicinity of the spindle motor 2 in the disk drive apparatus of the
ninth embodiment. FIG. 16 is a cross-sectional plan view showing
the vicinity only of the hollow ring member 23c provided on the
turn table 10c in the disk drive apparatus of the ninth embodiment.
Here, elements essentially identical to those in the disk drive
apparatus of the first and second embodiments or to those in the
disk drive apparatus shown in FIGS. 24 and 25 are designated by the
same reference numerals, and descriptions of such elements are
omitted.
[0209] In the ninth embodiment of the present invention, as shown
in FIGS. 15 and 16, the hollow ring member 23c is provided on the
turn table 10c, and the spherical balancer 22d containing a
plurality of magnetic spherical bodies 24e is formed therein. An
electromagnet 40 is mounted outside the outer wall 43 of the hollow
ring member 23c. The electromagnet 40 consists of an iron core 41
and a coil 42 wound around the center portion of the iron core 41.
The iron core 41 is formed with its inside end face facing the
outer wall 43 of the hollow ring member 23c with a prescribed gap
provided therebetween, and is fixed to the sub-base 6. In other
respects, the construction is the same as that of the previously
described seventh embodiment.
[0210] In the thus constructed ninth embodiment, a magnetic field
is created by supplying current through the coil 42, thus exerting
an attractive force on the magnetic spherical bodies 24e. With this
attractive force, the magnetic spherical bodies 24e are urged in a
direction toward the outer circumferential wall 25c of the hollow
ring member 23c. Thus, when the disk 1 is stationary, or when the
rotational frequency of the disk 1 is low in an early stage of the
acceleration process or at the end of the deceleration process, and
the centrifugal force acting on the magnetic spherical bodies 24e
is small, the magnetic spherical bodies 24e are made to stick to
the outer circumferential wall 25c of the hollow ring member 23c by
flowing current through the coil 42. The disk drive apparatus of
the ninth embodiment can thus prevent the spherical bodies from
hitting against each other or against the inner wall surfaces of
the hollow ring member 23c.
[0211] Further, in the disk drive apparatus of the ninth
embodiment, when the disk 1 is rotating at a frequency high enough
to generate a centrifugal force that is sufficient to make the
magnetic spherical bodies 24e stick to the outer circumferential
wall 25c, the current to the coil 42 is cut off. In this way, the
magnetic spherical bodies 24e are allowed to move to the position
opposite the disk mass center G1, as in the previously described
first embodiment.
[0212] With this construction of the disk drive apparatus of the
ninth embodiment, the magnitude of the attractive force acting on
the magnetic spherical bodies 24e can be controlled by controlling
the amount of current flown to the coil 42, and also, switching
between the attracted state and movable state can be made easily by
switching the current to the coil 42 on and off. Therefore, when
attraction is necessary, a sufficient current is flown through the
coil 42, and thus, the generation of noise by colliding magnetic
spherical bodies 24e can be reliably prevented. Moreover, when the
disk 1 is rotating at high speed, and the vibration due to the
imbalance force increases, the current to the coil 42 is cut off,
thereby allowing the magnetic spherical bodies 24e to move to the
position opposite the disk mass center G1 so that the vibration
suppressing effect can be fully utilized.
[0213] As described above, with the construction of the ninth
embodiment of the present invention, a disk drive apparatus capable
of high speed rotation can be achieved that ensures stable
recording or reproducing even when a disk with a greatly unbalanced
mass is rotated at high speed, and that does not generate
undesirable noise not only during high speed rotation but also
during the acceleration or deceleration of disk rotation.
[0214] <<Tenth Embodiment>>
[0215] Next, a disk drive apparatus according to a tenth embodiment
of the present invention will be described with reference to
drawing. FIG. 17 is a cross-sectional side view showing the
vicinity of the turn table 110 in the disk drive apparatus of the
tenth embodiment. Here, elements essentially identical to those in
the disk drive apparatus of the first and second embodiments or to
those in the disk drive apparatus shown in FIGS. 24 and 25 are
designated by the same reference numerals, and descriptions of such
elements are omitted.
[0216] In the tenth embodiment of the present invention, as shown
in FIG. 17, the hollow ring member 23d is formed around the outer
circumference of a magnet 18 built into the clamper 16d, and a
plurality of magnetic spherical bodies 24e are contained inside the
hollow ring member 23d. The spherical balancer 22e consisting of
the hollow ring member 23d and the magnetic spherical bodies 24e is
formed integrally with the clamper 16d.
[0217] As shown in FIG. 17, in the disk drive apparatus of the
tenth embodiment, a back yoke 50 is fixed to the upper surface of
the magnet 18. The outer radius of the back yoke 50 is formed
larger than the outer radius of the magnet 18. An elastic member 52
such as a vibration isolating rubber is attached around the outer
circumferential surface 51 of the magnet 18. In other respects, the
construction is the same as that of the previously described first
embodiment.
[0218] In the thus constructed tenth embodiment, the magnetic
spherical bodies 24e are attracted and held by utilizing the magnet
18, which generates an attractive force to clamp the disk 1 in
position, instead of the magnet 30 in the seventh embodiment shown
in FIG. 13.
[0219] The magnetic spherical bodies 24e are acted upon by the
attractive force from the magnet 18 so that the magnetic spherical
bodies 24e are urged at all times in a direction toward the outer
circumferential surface 51 of the magnet 18. As a result, when the
disk 1 is stationary, or when the rotational frequency of the disk
1 is low, and the centrifugal force acting on the magnetic
spherical bodies 24e is small, the magnetic spherical bodies 24e
are made to adhere to the elastic member 52 attached around the
outer circumferential surface 51 of the magnet 18 by the attractive
force of the magnet 18. Accordingly, as in the previously described
seventh embodiment, when vibration is applied from the outside
during transportation of the disk drive apparatus, or when the disk
1 is in an early stage of the acceleration process or at the end of
the deceleration process, the spherical bodies are prevented from
hitting against each other or against the inner wall surfaces of
the hollow ring member 23d, and generation of undesirable noise can
thus be avoided.
[0220] The magnet 18 is magnetized in vertical directions in order
to generate a sufficient attractive force to clamp the disk 1.
Therefore, the magnetic spherical bodies 24e are attracted and held
by utilizing the magnetic flux leaking to the side faces of the
magnet 18, and the attractive force acting on the magnetic
spherical bodies 24e is far smaller than the attractive force
acting between the magnet 18 and the counter yoke 15.
[0221] On the other hand, if the attractive force acting between
the magnet 18 and the counter yoke 15 is made too large, a very
large force will be required to overcome the attractive force when
unloading the disk 1 from the turn table 110. As a result, the
current consumption of the loading motor (not shown) for unloading
will have to be increased, and in some case, trouble may occur,
such as an inability to unload the disk. Therefore, it is not
desirable to increase more than necessary the magnitude of the
magnetic field generated by the magnet 18, and if a sufficient
attractive force to attract and hold the magnetic spherical bodies
24e is to be obtained from the magnet 18, the magnetic flux leakage
to the side walls of the magnet 18 must be utilized to the
full.
[0222] For this reason, in the disk drive apparatus of the tenth
embodiment, the outer radius of the back yoke 50 fixed to the upper
surface of the magnet 18 is formed larger than the outer radius of
the magnet 18. With this construction of the disk drive apparatus
of the tenth embodiment, when the rotational frequency of the disk
1 is low, the magnetic spherical bodies 24e are made to stick
securely to the elastic member 52 attached around the outer
circumferential surface 51 of the magnet 18. That is, when the
rotational frequency of the disk 1 is low, if the magnetic
spherical bodies 24e try to come off the elastic member 52 because
of centrifugal force, the attractive force continues to act upon
the magnetic spherical bodies 24e since magnetic paths are formed
from the outer circumferential edges of the back yoke 50 to the
bottom surface of the magnet 18 through the magnetic spherical
bodies 24e.
[0223] Accordingly, in the disk drive apparatus of the tenth
embodiment, the magnetic spherical bodies 24e can be attracted and
held securely until a high rotational frequency is reached. That
is, the disk drive apparatus of the tenth embodiment can securely
hold the magnetic spherical bodies 24e attracted to the elastic
member 52 until the rotational frequency is reached where a
centrifugal force is generated that is sufficient to make the
magnetic spherical bodies 24e stick to the outer circumferential
wall 25d of the hollow ring member 23d.
[0224] When the rotational frequency of the disk 1 is lowered, the
magnetic spherical bodies 24e sticking to the outer circumferential
wall 25d are drawn to the outer circumferential surface 51 of the
magnet 18 by the attractive force of the magnet 18. At this time,
since the elastic member 52 is attached around the outer
circumferential surface 51 of the magnet 18, the magnetic spherical
bodies 24e do not hit directly against the magnet 18, but hit
against the elastic member 52 which absorbs the shock. Accordingly,
the disk drive apparatus of the tenth embodiment can avoid the
generation of undesirable noise as well as trouble due to the shock
when stopping the rotation of the disk 1 or when performing
recording or reproducing by reducing the rotational frequency of
the disk 1.
[0225] Furthermore, according to the tenth embodiment of the
present invention, since the magnet 18, which generates an
attractive force for clamping the disk 1, is utilized to attract
and hold the magnetic spherical bodies 24e, there is no need to
provide a separate magnet for attracting and holding them, and the
number of components can thus be reduced.
[0226] Here, the elastic member 52 attached to the magnet 18 may be
a cover formed, for example, from a vibration isolating material,
or may be formed by coating the outer circumferential surface 51 of
the magnet 18 with a vibration isolating material.
[0227] As described above, with the construction of the tenth
embodiment of the present invention, a disk drive apparatus can be
achieved that ensures stable recording or reproducing even when a
disk with a greatly unbalanced mass is rotated at high speed, and
that does not generate undesirable noise not only during high speed
rotation but also during the acceleration or deceleration of disk
rotation, or even when performing recording or reproducing by
varying the rotational speed as needed.
[0228] <<Eleventh Embodiment>>
[0229] Next, a disk drive apparatus according to an eleventh
embodiment of the present invention will be described with
reference to drawing. FIG. 18 is a cross-sectional side view
showing the vicinity of the clamper 16d and the turn table 110 in
the disk drive apparatus of the eleventh embodiment. Here, elements
essentially identical to those in the disk drive apparatus of the
first and second embodiments or to those in the disk drive
apparatus shown in FIGS. 24 and 25 are designated by the same
reference numerals, and descriptions of such elements are
omitted.
[0230] In the construction of the foregoing tenth embodiment, the
elastic member 52 formed from a vibration isolating rubber or the
like was attached around the outer circumferential surface 51 of
the magnet 18; in the disk drive apparatus of the eleventh
embodiment of the present invention, on the other hand, an elastic
member 53 formed from a vibration isolating rubber or the like is
also attached around the end faces and lower surface portions of
the back yoke 50 protruding outward of the outer circumferential
surface 51 of the magnet 18. In other respects, the construction is
the same as that of the foregoing tenth embodiment.
[0231] In the thus constructed disk drive apparatus of the eleventh
embodiment, since the elastic member 53 is also provided on the
back yoke 50, the occurrence of undesirable noise and trouble due
to shock can be avoided.
[0232] Even when the rotational frequency of the disk 1 is lowered
during deceleration of the disk rotation, and the magnetic
spherical bodies 24e are drawn to the outer circumferential surface
51 of the magnet 18 by the attractive force of the magnet 18, if
the magnetic spherical bodies 24e hit against the end faces or
lower surface portions of the back yoke 50, not against the elastic
member 52 attached around the outer circumferential surface 51 of
the magnet 18, the occurrence of undesirable noise and trouble due
to shock can be avoided.
[0233] When the disk 1 is placed in a horizontal position, there is
little possibility of the magnetic spherical bodies 24e hitting
against the back yoke 50 because of the force of gravity, but, in
particular, when the disk 1 is held in a vertical position, in the
disk drive apparatus placed longitudinally, there aries the
possibility that the magnetic spherical bodies 24e will be drawn
toward the back yoke 50.
[0234] As described above, with the construction of the eleventh
embodiment of the present invention, an excellent disk drive
apparatus can be achieved that ensures stable recording or
reproducing even when a disk with a greatly unbalanced mass is
rotated at high speed, and that does not generate undesirable noise
regardless of whether the disk drive apparatus is set in a
horizontal position or a vertical position.
[0235] <<Twelfth Embodiment>>
[0236] Next, a disk drive apparatus according to a twelfth
embodiment of the present invention will be described with
reference to drawing. FIG. 19 is a cross-sectional side view
showing the vicinity of the spindle motor 2 in the disk drive
apparatus of the twelfth embodiment. Here, elements essentially
identical to those in the disk drive apparatus of the first and
second embodiments or to those in the disk drive apparatus shown in
FIGS. 24 and 25 are designated by the same reference numerals, and
descriptions of such elements are omitted.
[0237] In the disk drive apparatus of the twelfth embodiment of the
present invention, the turn table 10c, which supports the clamp
area 11 of the disk 1 in rotatable fashion, is fixed to the spindle
shaft 21 of the spindle motor 2, as shown in FIG. 19. Further, a
positioning taper 60 is formed on the side faces of the boss 114 of
the turn table 10c, and a ring-shaped magnet 61 is embedded inside
it.
[0238] In the clamper 16e, there is formed a tapered hole 63 for
centering the clamper 16e by engaging on the positioning taper 60
formed on the turn table 10c. A ring-shaped counter yoke 64 is
fixed to the upper portion of the tapered hole 63.
[0239] A flat contacting portion 19 which contacts the disk 1 is
formed on the lower surface of the clamper 16e. Further, the
clamper 16e is provided with a hollow ring member 23e concentric
with the center axis of the tapered hole 63. Inside the hollow ring
member 23e are contained a plurality of magnetic spherical bodies
24e in movable fashion, and a spherical balancer 22f comprising of
the hollow ring member 23e and the magnetic spherical bodies 24e is
formed integrally with the clamper 16e.
[0240] When the disk 1 is clamped by the clamper 16e, the disk 1 is
centered and held on the turn table 10c with the clamp hole 12 in
the disk 1 engaging on the boss 114 of the turn table 10c. Then,
the disk 1 is clamped in position by the attractive force acting
between the counter yoke 64 fixed to the clamper 16e and the magnet
61 fixed to the turn table 10c. At this time, since positioning is
done with the tapered hole 63 formed in the clamper 16e engaging on
the positioning taper 60 provided on the turn table 10c, the hollow
ring member 23e provided concentrically with the center axis of the
tapered hole 63 is positioned substantially concentric with the
rotational center axis P0 of the spindle motor 2. The clamper 16e
with the disk 1 clamped in this way is driven by the spindle motor
2 for rotation in integral fashion with the disk 1 and the turn
table 10c.
[0241] Further, as in the previously described first embodiment,
the disk drive apparatus of the twelfth embodiment uses a
low-stiffness insulator (elastic member) 7 to join the sub-base 6
to the main base 8. In the disk drive apparatus of the twelfth
embodiment, the primary resonance frequency in a direction parallel
to the recording surface of the disk 1 in the mechanical vibration
of the sub-base 6 due to the deformation of the insulator 7 is set
at about 60 Hz, which is lower than the rotational frequency of the
disk 1 (about 100 Hz).
[0242] In the thus constructed twelfth embodiment, when a disk 1
with a large unbalance amount is rotated at about 100 Hz, the
magnetic spherical bodies 24e are concentrated in a position
substantially diametrically opposite the disk mass center G1 by the
moving force R, as in the previously described first embodiment
shown in FIG. 2. As a result, the imbalance force F acting on the
disk mass center G1 is offset by the centrifugal force Q acting on
the magnetic spherical bodies 24e, and the vibration of the
sub-base 6 is thus suppressed.
[0243] In the disk drive apparatus of the twelfth embodiment, the
magnetic spherical bodies 24e are acted upon by the attractive
force arising from the leakage magnetic flux from the counter yoke
64 and the magnet 61, so that the magnetic spherical bodies 24e are
urged at all times in a direction toward the outer end faces of the
counter yoke 64. Accordingly, when the disk 1 is stationary, or
when the rotational frequency of the disk 1 is low and the
centrifugal force acting on the magnetic spherical bodies 24e is
small, the magnetic spherical bodies 24e are made to stick to the
outer end faces of the counter yoke 64 by the attractive force from
the counter yoke 64.
[0244] As described above, in the disk drive apparatus of the
twelfth embodiment, as in the previously described seventh
embodiment, the spherical bodies are prevented from hitting against
each other or against the inner wall surfaces of the hollow ring
member 23e when vibration is applied from the outside during
transportation of the disk drive apparatus or when the disk 1 is in
an early stage of the acceleration process or at the end of the
deceleration process, and in this way, the occurrence of
undesirable noise can be avoided.
[0245] As described above, in the disk drive apparatus of the
twelfth embodiment of the present invention, a disk loading
mechanism is provided which consists of the clamper 16e provided
with the counter yoke 64 and the turn table 10c provided with the
magnet 61. Using such a disk loading mechanism also, a disk drive
apparatus can be achieved that ensures stable recording or
reproducing even when a disk 1 with a greatly unbalanced mass is
rotated at high speed, and that prevents the generation of
undesirable noise.
[0246] <<Thirteenth Embodiment>>
[0247] Next, a disk drive apparatus according to a thirteenth
embodiment of the present invention will be described with
reference to drawing. FIG. 20 is a cross-sectional side view
showing the vicinity of the turn table 10c in the disk drive
apparatus of the thirteenth embodiment. Here, elements essentially
identical to those in the disk drive apparatus of the first and
second embodiments or to those in the disk drive apparatus shown in
FIGS. 24 and 25 are designated by the same reference numerals, and
descriptions of such elements are omitted.
[0248] In the disk drive apparatus of the thirteenth embodiment of
the present invention, as shown in FIG. 20, an elastic member 65
formed from a vibration isolating rubber or the like is attached
around the circumference of the counter yoke 64 shown in the
construction of the foregoing twelfth embodiment. In other
respects, the construction is the same as that of the foregoing
twelfth embodiment.
[0249] In the thus constructed thirteenth embodiment, when the
rotational frequency of the disk 1 is lowered during deceleration
of the disk rotation, and the magnetic spherical bodies 24e are
drawn to the outer end faces of the counter yoke 64 by the
attractive force from the counter yoke 64, the provision of the
elastic member 65 on the counter yoke 64 serves to prevent the
magnetic spherical bodies 24e from hitting directly against the
counter yoke 64; the magnetic spherical bodies 24e instead hit
against the elastic member 65 which absorbs the shock, and the
magnetic spherical bodies 24e are thus made to stick to the elastic
member 65. In this way, the generation of undesirable noise and
trouble due to the shock can be avoided.
[0250] As described above, in the disk drive apparatus of the
thirteenth embodiment of the present invention, a disk loading
mechanism is provided which comprises of the clamper 16e provided
with the counter yoke 64 and the turn table 10c provided with the
magnet 61. Using such a disk loading mechanism also, a disk drive
apparatus can be achieved that ensures stable recording or
reproducing even when a disk 1 with a greatly unbalanced mass is
rotated at high speed, and the generation of undesirable noise can
be prevented reliably.
[0251] <<Fourteenth Embodiment>>
[0252] Next, a disk drive apparatus according to a fourteenth
embodiment of the present invention will be described with
reference to drawing. FIG. 21 is a cross-sectional side view
showing the vicinity of the turn table 110 in the disk drive
apparatus of the fourteenth embodiment. Here, elements essentially
identical to those in the disk drive apparatus of the first and
second embodiments or to those in the disk drive apparatus shown in
FIGS. 24 and 25 are designated by the same reference numerals, and
descriptions of such elements are omitted.
[0253] In the disk drive apparatus of the fourteenth embodiment of
the present invention, the clamper 16f comprises an upper case 70
and a lower case 71, as shown in FIG. 21. The upper case 70 and the
lower case 71 are assembled together with the outer circumferential
side wall 73 of the lower case 71 positioned outside the outer
circumferential side wall 72 of the upper case 70. An elastic
member 74 is sandwiched between the outer circumferential side wall
72 of the upper case 70 and the outer circumferential side wall 73
of the lower case 71 in intimately contacting relationship.
[0254] As shown in FIG. 21, the hollow ring member 23f is formed by
an upper inner surface of the upper case 70 of the clamper 16f, an
inner surface of the outer circumferential side wall 72, a bottom
inner surface of the lower case 71, and an outer circumferential
surface of the magnet 18, and a plurality of magnetic spherical
bodies 24e are contained inside the hollow ring member 23f. In this
way, in the disk drive apparatus of the fourteenth embodiment, a
spherical balancer 22g consisting of the hollow ring member 23f and
the magnetic spherical bodies 24e is formed integrally with the
clamper 16f.
[0255] Further, in the disk drive apparatus of the fourteenth
embodiment, the back yoke 50 is fixed to the upper surface of the
magnet 18, and the elastic member 53 is attached rigidly to the
back yoke 50, as in the previously described eleventh embodiment.
Furthermore, the elastic member 52 is attached rigidly to the outer
circumferential surface 51 of the magnet 18. In other respects, the
construction is the same as that of the previously described first
embodiment.
[0256] In the thus constructed disk drive apparatus of the
fourteenth embodiment, when the disk 1 is stationary, or when the
rotational frequency of the disk 1 is low during acceleration or
deceleration, and the centrifugal force acting on the magnetic
spherical bodies 24e is small, the magnetic spherical bodies 24e
are made to stick to the elastic member 52 or the elastic member 53
by the attractive force of the magnet 18, as in the previously
described eleventh embodiment. In this condition, when the rotation
of the disk 1 is accelerated and the rotational frequency increases
to the point where the centrifugal force acting on the magnetic
spherical bodies 24e exceeds the attractive force of the magnet 18,
the magnet spherical bodies 24e sticking to the elastic member 52
or the elastic member 53 are thrown toward the outer
circumferential wall 25f and hit against the outer circumferential
wall 25f.
[0257] When fs denotes the rotational frequency that causes the
magnetic spherical bodies 24e to be thrown toward the outer
circumferential wall 25f, fh denotes the rotational frequency that
generates a centrifugal force sufficient to hold the magnetic
spherical bodies 24e adhering to the outer circumferential wall
25f, and fn denotes the rotational frequency where the vibration
caused by the unbalance of the disk 1 becomes undesirably large, it
is desirable that the relation between them be set as
fh<fs<fn, as in the previously described seventh embodiment.
That is, it is desirable that the attractive force of the magnet 18
be increased and fs be set sufficiently higher than fh so that the
magnetic spherical bodies 24e can be attracted and held securely
even if vibration or shock is applied from the outside when the
rotational frequency of the disk 1 is lower than fh. However, the
higher the fs is set, the higher the speed at which the magnetic
spherical bodies 24e collide against the outer circumferential wall
25f, and there arises the possibility that the shock caused by the
collision of the magnetic spherical bodies 25e is transmitted to
the disk 1, causing the disk 1 to vibrate and adversely affecting
recording or reproducing operations, or increasing the colliding
noise to an undesirable level.
[0258] To address this, in the disk drive apparatus of the
fourteenth embodiment, the elastic member 74 is sandwiched between
the outer circumferential wall 72 of the upper case 70 and the
outer circumferential wall 73 of the lower case 71. With the
damping effect of the elastic member 74, the shock caused when the
magnetic spherical bodies 24e collide against the outer
circumferential wall 25f is absorbed, preventing the shock from
being transmitted to the disk 1, while reducing the magnitude of
the colliding noise. Accordingly, even if the attractive force of
the magnet 18 acting on the magnetic spherical bodies 24e is
increased so that the magnetic spherical bodies 24e can be
attracted and held securely when the rotational frequency of the
disk 1 is low, the occurrence of trouble can be prevented, avoiding
situations where adverse effects are caused to recording or
reproducing operations by the shock when the magnetic spherical
bodies 24e collide against the outer circumferential wall 25f
during the acceleration of the rotation of the disk 1, or where the
colliding noise increases to an undesirable level.
[0259] As described above, with the construction of the fourteenth
embodiment of the present invention, a disk drive apparatus can be
achieved that ensures stable recording or playback even when a disk
with a greatly unbalanced mass is rotated at high speed, and that
prevents the generation of undesirable noise even if vibration or
shock is applied to the disk drive apparatus when the disk is
stationary or is rotating at slow speed.
[0260] <<Fifteenth Embodiment>>
[0261] Next, a disk drive apparatus according to a fifteenth
embodiment of the present invention will be described with
reference to drawing. FIG. 22 is a cross-sectional side view
showing the vicinity of the turn table 110 in the disk drive
apparatus of the fifteenth embodiment. Here, elements essentially
identical to those in the disk drive apparatus of the first and
second embodiments or to those in the disk drive apparatus shown in
FIGS. 24 and 25 are designated by the same reference numerals, and
descriptions of such elements are omitted.
[0262] As in the foregoing fourteenth embodiment, in the fifteenth
embodiment of the present invention shown in FIG. 22, the hollow
ring member 23f is formed by the upper inner surface of the upper
case 70, the inner surface of the outer circumferential side wall
72, the bottom inner surface of the lower case 71, and the outer
circumferential surface of the magnet 18. As shown in FIG. 22, in
the disk drive apparatus of the fifteenth embodiment, an elastic
member 75 is sandwiched between the lower end portion of the outer
circumferential side wall 72 of the upper case 70 and the bottom
inner surface of the lower case 71 in intimately contacting
relationship. In other respects, the construction is the same as
that of the foregoing fourteenth embodiment.
[0263] In the thus constructed disk drive apparatus of the
fifteenth embodiment, as in the foregoing fourteenth embodiment,
the vibration of the outer circumferential side wall 72 caused when
the magnetic spherical bodies 24e collide against the outer
circumferential wall 25f is damped with the vibration damping
effect of the elastic member 75 sandwiched between the lower end
portion of the outer circumferential side wall 72 of the upper case
70 and the bottom upper surface of the lower case 71, thus
preventing the vibration from being transmitted to the disk 1,
while reducing the magnitude of the colliding noise. Accordingly,
even when the attractive force of the magnet 18 is increased to
such a level that the magnetic spherical bodies 24e can be
attracted and held securely even if vibration or shock is applied
to the disk drive apparatus when the disk is stationary or is
rotating at slow speed, the occurrence of trouble can be prevented,
avoiding situations where adverse effects are caused to recording
or reproducing operations by the shock when the magnetic spherical
bodies 24e collide against the outer circumferential wall 25f, or
where the colliding noise increases to an undesirable level.
[0264] Furthermore, in the disk drive apparatus of the fifteenth
embodiment, the upper case 70 and lower case 71 of the clamper 16f
can be easily assembled comparison with the disk drive apparatus of
the foregoing fourteenth embodiment. This is because in the disk
drive apparatus of the fifteenth embodiment, the absence of the
elastic member 74 between the outer circumferential side wall 72 of
the upper case 70 and the outer circumferential side wall 73 of the
lower case 71 makes it possible to assemble the cases by pressing
the lower end portion of the outer circumferential side wall 72 of
the upper case 70 against the elastic member 75 on the bottom upper
surface of the lower case 71.
[0265] As described above, with the construction of the fifteenth
embodiment of the present invention, as in the foregoing fourteenth
embodiment, a disk drive apparatus can be achieved that ensures
stable recording or reproducing even when a disk with a greatly
unbalanced mass is rotated at high speed, and that prevents the
generation of undesirable noise even if vibration or shock is
applied to the disk drive apparatus when the disk is stationary or
is rotating at slow speed. <<Sixteenth Embodiment>>
[0266] Next, a disk drive apparatus according to a sixteenth
embodiment of the present invention will be described with
reference to drawing. FIG. 23 is a cross-sectional side view
showing the vicinity of the spindle motor 2 in the disk drive
apparatus according to the sixteenth embodiment of the present
invention. Here, elements essentially identical to those in the
disk drive apparatus of the first and second embodiments or to
those in the disk drive apparatus shown in FIGS. 24 and 25 are
designated by the same reference numerals, and descriptions of such
elements are omitted.
[0267] In the disk drive apparatus of the sixteenth embodiment of
the present invention, the hollow ring member 23g is provided on
the rotor 80 of the spindle motor 2. Inside the hollow ring member
23g of the sixteenth embodiment are contained a plurality of
spherical bodies 24 in movable fashion, and the hollow ring member
23g and the spherical bodies 24 together constitute a spherical
balancer 22f. The clamper 116 and the turn table 110 are the same
as those used in the conventional disk drive apparatus; in other
respects, the construction is the same as that of the previously
described first embodiment.
[0268] As in the case of the previously described first embodiment
(FIG. 1), fourth embodiment (FIG. 10), and seventh embodiment (FIG.
13), the sixteenth embodiment aims at solving the problem that the
center axis P2 of the outer circumferential wall 25g of the hollow
ring member 23g becomes displaced from the rotational center axis
P0 of the spindle motor, and by managing the concentricity of the
hollow ring member 23g with respect to the rotational center axis
P0 of the spindle motor in advance, a stable effect of the
spherical balancer 22f can be obtained consistently. In the
sixteenth embodiment, the same effect can be obtained if a liquid
26, instead of the spherical bodies 24, is sealed inside the hollow
ring member 23g provided on the rotor 80.
[0269] As in the disk drive apparatus of the sixteenth embodiment
of the present invention shown in FIG. 23, the hollow ring member
23g containing the plurality of spherical bodies 24 in movable
fashion is provided spaced apart from an unbalanced disk 1 in the
direction of the rotational axis P0 of the spindle motor 2. In this
case, the center of mass of the sub-base 6 and the entire component
assembly mounted on the sub-base 6 is denoted by G2. When the
moment FbL1 about the center of mass G2 of the entire component
assembly due to the imbalance force acting on the center of mass G1
of the disk 1 is compared with the moment QL2 about the center of
mass G2 due to the centrifugal force Q acting on the spherical
bodies 24 clustered in the position directly opposite to the
direction of the imbalance force F, if the centrifugal force Q and
the imbalance force F are equal in magnitude, the moment FL1 of the
unbalance force F is larger because L1 is larger than L2. The
sub-base 6 generates rotational vibrations due to their resultant
moment M. Therefore, in cases where rotational vibrations become a
problem, if the hollow ring member 23 is provided on an element
near the disk 1, for example, on the clamper 116 or the turn table
110, and the spherical bodies 24 or the liquid 26 is placed
therein, the difference between the moment FL1 and the moment QL2
can be reduced.
[0270] Further, if there is a limitation on the size of the hollow
ring member 23g, and the mass of the spherical bodies 24 or liquid
26 to be contained in the hollow ring member 23g cannot be made
sufficiently large, or if the unbalance amount of the disk 1 is
extremely large, the centrifugal force Q becomes smaller than the
imbalance force F, increasing the difference between the moment FL1
and the moment QL2. In such cases, however, distance L2 between the
points of action of the center of mass G2 and the centrifugal force
Q is made larger by forming the hollow ring member, for example, on
the upper part of the clamper 116. In this way, the difference
between the moment FL1 and the moment QL2 can be reduced, reducing
the resultant moment M. Accordingly, even in cases where the
vibration in the direction parallel to the disk surface of the disk
1 cannot be suppressed sufficiently, the rotational vibration due
to the resultant moment M can be reduced.
[0271] In the first to sixteenth embodiments, the operation and
effect have been described when an unbalance is contained in the
disk 1, but if there is an unbalance in any member driven for
rotation by the spindle motor 2, such as the turn table 110, the
rotor of the spindle motor 2, or the clamper 116, the effect of
suppressing the vibration due to that unbalance can also be
obtained.
[0272] As described above, according to the disk drive apparatus of
the present invention, by providing a balancer containing a
plurality of spherical bodies or a liquid so as to be rotatable in
integral fashion with a disk the vibration of the sub-base due to
disk imbalance can be suppressed reliably, and a disk drive
apparatus can be achieved that ensures stable recording or
reproducing even when an unbalanced disk is rotated at high speed,
and that is quiet in operation, has excellent anti-vibration,
anti-shock characteristics, and is capable of high-speed data
transfer.
INDUSTRIAL APPLICABILITY
[0273] The disk drive apparatus of the present invention suppresses
vibrations due to mass imbalance of a disk or the like, and the
present invention can be applied to every kind of disk drive
apparatus that records data on a disk or play back data recorded on
a disk while rotating the disk. For example, by applying the
technological concept of the present invention to a playback-only
optical disk drive apparatus for CD, CD-ROM, etc. or to a
recordable apparatus that requires more precise relative distance
control between the optical head and track on the disk (tracking
control), a more reliable apparatus can be achieved.
[0274] Furthermore, undesirable vibrations due to disk imbalance
can be suppressed not only in an apparatus that performs
non-contacting recording or reproducing using an optical head, but
also in an apparatus that performs recording or reproducing on a
disk using a contact-type magnetic head or floating-type magnetic
head.
* * * * *