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United States Patent Application
20040111737
Kind Code
A1
Masaki, Kiyoshi ; et al.
June 10, 2004
Disk drive apparatus
Abstract
The present invention is intended to provide a disk drive apparatus capable of suppressing the occurrence of undesirable vibration due to the imbalance of a disk and capable of carrying out high-rate transfer, wherein a balancer is formed so as to accommodate a predetermined number of spherical bodies in a ring-shaped track portion having a predetermined shape, and this balancer is provided so as to be rotatable integrally and coaxially with the disk. In addition, in the disk drive apparatus of the present invention, the ring-shaped track of the balancer is divided into plural tracks by partition walls or the like, and a ball used as a balance member is disposed so as to be movable on each divided track. Furthermore, the disk drive apparatus of the present invention is configured so that the disk is held on both sides or one side thereof by using four or more projections or rubber sheets.
Inventors:
Masaki; Kiyoshi
(Amagasaki-shi, JP)
, Mihara; Kazuhiro
(Moriguchi-shi, JP
)
, Yoshida; Shuichi
(Osaka-shi, JP
)
, Naka; Teruyuki
(Isumi-Shi, JP
)
, Fukuyama; Sachio
(Matsuyama-shi, JP
)
, Urayama; Noriaki
(Matsuyama-shi, JP
)
, Kikugawa; Masaaki
(Matsuyama-shi, JP
)
, Maruoka; Makoto
(Matsuyama-shi, JP
)
, Obayashi; Shinichiro
(Onsen-gun, JP
)
Correspondence Name and Address:
ONE COMMERCE SQUARE 2005 MARKET STREET, SUITE 2200
AKIN GUMP STRAUSS HAUER & FELD L.L.P.
PHILADELPHIA
PA
19103-7013
US
Series Code:
718119
Filed:
November 19, 2003
U.S. Current Class:
720/715;
720/702; 720/706
U.S. Class at Publication:
720/715;
720/702; 720/706
Intern'l Class:
G11B 017/028
Claims
1. A disk drive apparatus comprising: a turntable having four or more projections each of which has predetermined height, which are arranged at positions wherein a circumference is divided at equal intervals, and the tips of which are substantially on the same plane, for supporting a mounted disk by using said four or more projections; a clamper having four or more projections each of which has predetermined height, which are arranged at positions wherein a circumference is divided at equal intervals, and holding said disk between these projections and the projections on said turntable; and positioning means for holding said disk between the projections on said turntable and the projections on said clamper disposed opposite to each other.
2. A disk drive apparatus comprising: a turntable having four or more projections each of which has predetermined height, which are arranged at positions wherein a circumference is divided at equal intervals, and the tips of which are substantially on the same plane, for supporting a mounted disk by using said four or more projections; a clamper having four or more projections each of which has predetermined height, which are arranged at positions wherein a circumference is divided at equal intervals, and holding said disk between these projections and the projections on said turntable; positioning means for holding said disk between the projections on said turntable and the projections on said clamper disposed opposite to each other; a sub-base to which a spindle motor for rotating said disk is secured; a main base over which said sub-base is installed via elastic bodies; and a balancer having arc-shaped tracks with a plurality of arcs having a central angle of less than 360 degrees and balance members provided so as to be movable on said arc-shaped tracks, and provided so as to be rotatable integrally with said disk.
3. A disk drive apparatus comprising: a turntable provided with a ring-shaped rubber sheet stuck to a disk mounting face thereof on which a disk used as a recording medium is mounted; and a clamper having four or more projections each of which has predetermined height, which are arranged at positions wherein a circumference is divided at equal intervals, the tips of which are substantially on the same plane, and holding said disk between said projections and said ring-shaped rubber sheet.
4. A disk drive apparatus comprising: a turntable having four or more projections each of which has predetermined height, which are arranged at positions wherein a circumference is divided at equal intervals, and the tips of which are substantially on the same plane, for supporting a mounted disk by using said four or more projections; and a clamper provided with a ring-shaped rubber sheet stuck to a disk mounting face thereof for holding said disk between said ring-shaped rubber sheet and said projections of said turntable.
Description
TECHNICAL FIELD
[0001] The present invention relates to a disk drive apparatus capable of carrying out stable recording and reproduction by suppressing undesirable vibration and noise caused by an imbalance on a disk used as a recording medium.
PRIOR ART
[0002] In recent years, in disk drive apparatuses for recording/reproducing data, high-speed disk rotation is being advanced to improve data transfer rate. For example, in a CD-ROM disk drive apparatus, its rotation speed has increased from a conventional value of the order of 5000 rpm to 6000 rpm or more. This tendency is similarly shown not only in the half-height disk drive apparatuses for desktop computers but also the low-profile disk drive apparatuses for notebook computers.
[0003] However, there are various disks; some disks have a mass imbalance due to nonuniform thickness, and other disks have a mass imbalance due to the paper seal stuck thereto to indicate the contents recorded thereon. The amount of the mass imbalance of the disk reaches about 1 gcm in the case when the amount is large. When this kind of disk is rotated at high speed, an eccentric centrifugal force (an imbalance force) acts on the rotation center of the disk, thereby causing a problem wherein the vibration due to the imbalance force is transmitted to the whole of the device. The magnitude of this imbalance force increases in proportion to the square of rotation frequency (Hz) (rotation frequency is the revolutions per unit time (revolutions/sec) of a disk 501). For example, when increasing the rotation speed of a disk having a mass imbalance of 1
gcm by only about 10%, from 5400 rpm to 600 rpm, the imbalance force increases about 1.2 times, and the vibration also increases significantly.
[0004] When the mass of the disk is M (g), and when the distance from the center of the disk to the center of gravity of the disk is L (cm), the mass imbalance amount A (gcm) is represented by A=M.times.L.
[0005] When this kind of unbalanced disk is rotated at high speed, noise occurs due to its vibration, the bearings of the spindle motor for rotating the disk are damaged, thereby causing a problem wherein stable recording and reproduction cannot be attained.
[0006] Furthermore, when this kind of disk drive apparatus is built in an apparatus such as a computer, the vibration is transmitted to other devices inside the apparatus, thereby also causing a problem of adversely affecting the devices.
[0007] For these reasons, to improve data transfer rate by rotating the disk at high speed, it is necessary to accomplish a task of suppressing undesirable vibration due to the mass imbalance of the disk.
[0008] An example of a conventional disk drive apparatus will be described below referring to the drawings.
[0009] FIG. 72 is a perspective view showing the main unit of the conventional disk drive apparatus. Referring to FIG. 72, a disk 1 is rotated by a spindle motor 2; and a head 3 reads data recorded on the disk 1 or writes data on the disk 1. A head drive mechanism 5, comprising a rack, a pinion and the like, converts the rotation motion of a head drive motor 4 into a linear motion, and transmits it to the head 3. The head 3 is configured so as to be moved in the radial direction of the disk 1 by this head drive mechanism 5. The spindle motor 2, the head drive motor 4 and the head drive mechanism 5 are mounted on a sub-base 6. Vibration and impact transmitted from outside the device to the sub-base 6 are dampened by insulators 7 (elastic bodies), and the sub-base 6 is mounted on a main base 8 via these insulators 7. The main unit of the disk drive apparatus shown in FIG. 72 is configured so as to be built on a computer or the like via a frame (not shown) installed in the main base 8.
[0010] FIG. 73 is a side sectional view showing the vicinity of the spindle motor 2 of the conventional disk drive apparatus. A turntable 110
is secured to the shaft 21 of the spindle motor 2 and rotatably supports the clamp area 11 of the disk 1. Inside the boss 14 formed on the turntable 110, a positioning ball 116 making contact with the corner portion of the clamp hole 12 of the disk 1 by virtue of a pressing means 113, such as a coil spring, is built in. In this way, the disk 1 is disposed at a predetermined position by the pressing operation of the positioning ball 116.
[0011] In the conventional disk drive apparatus configured as describe above, in the condition wherein the disk 1 is disposed and clamped on the turntable 110, by making the positioning ball 116 contact with the corner portion of the clamp hole 12, the disk 1 is aligned and held on the turntable 110 by the pressing force of the pressing means 113. The disk 1
held in this way is rotated integrally with the turntable 110 by the spindle motor 2.
[0012] However, in the conventional disk drive apparatus having the above-mentioned configuration, if the disk 1 having a mass imbalance due to nonuniform thickness, a seal, etc. stuck thereon is mounted and rotated at high speed, a centrifugal force (an imbalance force) F acts on the center of gravity G1 of the disk 1 shown in FIG. 73. The direction of the action rotates as the disk 1 rotates. This imbalance force F is transmitted to the sub-base 6 via the turntable 110 and the spindle motor 2; however, since the sub-base 6 is supported by the insulators 7 used as elastic bodies, it is whirled significantly by the imbalance force F while the insulators 7 are deformed. Since the magnitude of the imbalance force F is proportional to the product of the mass imbalance amount (represented by the unit of gcm) and the square of the rotation frequency, the vibration acceleration of the sub-base 6 increases drastically in close proportion to the square of the rotation frequency of the disk 1. As a result, such problems occur that noise was caused due to the resonance of the sub-base 6 itself and the head drive mechanism 5
mounted on the sub-base 6, and stable recording and reproduction became impossible due to significant vibration of the disk 1 and the head 3.
[0013] To cope with the above-mentioned problems, in the conventional disk drive apparatus, the spring constant of the insulators 7 was raised, or an elastic material, such as a leaf spring, was provided between the sub-base 6 and the main base 8 as counter measures to suppress the vibration amplitude of the sub-base 6.
[0014] However, if the rigidity of the connection portion between the sub-base 6 and the main base 8 was raised in this way, when vibration and impact were applied reversely from outside the drive device to the disk drive apparatus, the vibration and impact were directly transmitted to the sub-base 6 on which the disk 1, the head 3 and the like were mounted, and stable recording and reproduction became impossible, thereby causing a problem of reducing the so-called vibration-resistant and impact-resistant characteristics.
[0015] Furthermore, the vibration of the sub-base 6 due to the imbalance force F was transmitted to the outside of the disk drive apparatus via the main base 8 and the like, thereby causing a problem of adversely affecting other devices in the computer in which this disk drive apparatus was built.
[0016] Moreover, a large side pressure was applied to the bearings of the spindle motor 2 by the imbalance force F, whereby the loss of the shaft torque increased, and the bearings were damaged, thereby to cause a problem of shortening the service life of the bearings.
DISCLOSURE OF THE INVENTION
[0017] In consideration of the above-mentioned problems, the present invention is intended to provide a disk drive apparatus capable of carrying out stable recording and reproduction even when an unbalanced disk is rotated at high speed, and also capable of carrying out high-rate transfer while having high reliability in preventing vibration and impact from outside the device.
[0018] In order to solve the above-mentioned problems, the disk drive apparatus of the present invention is a device wherein a balancer having a ring-shaped track portion accommodating balance members is provided so as to rotate integrally with a disk mounted on the disk drive apparatus; and concrete means thereof are described below.
[0019] A disk drive apparatus in accordance with the present invention comprises:
[0020] a balancer provided so as to be rotatable integrally with a mounted disk and having a ring-shaped track portion accommodating balance members, wherein
[0021] the balancer satisfies the relationship of:
h.gtoreq.f.sup.2.times..vertline.A-Z.vertline.,
[0022] when the total mass of the above-mentioned balance members is M [g], the distance to the center of gravity of the total of the above-mentioned balance members from the center axis of the above-mentioned ring-shaped track portion is T [cm], a balance amount Z [gcm] is represented by:
Z=M.times.T,
[0023] when the maximum rotation frequency of the above-mentioned disk is f [Hz], the maximum of the mass imbalance amount of the above-mentioned disk is A [gcm], and a constant is h.
[0024] Therefore, in accordance with the disk drive apparatus of the present invention, even if the disk is rotated at high speed, vibration due to the mass imbalance of the disk can be suppressed securely, whereby it is possible to attain a disk drive apparatus capable of carrying out high-rate transfer.
[0025] A disk drive apparatus in accordance with the present invention from another point of view comprises:
[0026] a balancer provided so as to be rotatable integrally with a mounted disk and having a ring-shaped track portion accommodating spherical bodies, wherein
[0027] the balancer satisfies the relationship of:
h.gtoreq.f.sup.2.times..vertline.A-Z.vertline.,
[0028] when the radius of the above-mentioned spherical body is r [cm], the radius of the inner wall face of the outer periphery of the above-mentioned ring-shaped portion is S [cm], the number of the above-mentioned spherical bodies is n, the specific gravity of the above-mentioned spherical body is .rho., and a balance amount Z [gcm] is represented by:
Z={fraction (4/3)}.pi.r.sup.2.rho.(S-r).sup.2.times.sin[n sin.sup.-1{r/(S-r)})],
[0029] when the maximum rotation frequency of the above-mentioned disk is f [Hz], the maximum of the mass imbalance amount of the above-mentioned disk is A [gcm], and a constant is h.
[0030] Therefore, in accordance with the disk drive apparatus of the present invention, even if the disk is rotated at high speed, vibration due to the mass imbalance of the disk can be suppressed securely, whereby it is possible to attain a disk drive apparatus capable of carrying out high-rate transfer.
[0031] In a disk drive apparatus in accordance with the present invention, the above-mentioned constant h may be represented by:
h=fo.sup.2.times.Ao,
[0032] in the case when the maximum allowable rotation frequency wherein vibration becomes an allowable value or less is fo [Hz] at the time when a disk having a mass imbalance amount Ao [gcm] is rotated in a condition wherein the above-mentioned balance amount Z=0 [gcm].
[0033] Furthermore, in a disk drive apparatus in accordance with the present invention, it is preferable that the diameter of a disk to be mounted is 12 [cm] or less, and that the above-mentioned constant h is 8100.
[0034] A disk drive apparatus in accordance with the present invention from another point of view comprises:
[0035] a head for carrying out recording or reproduction on a mounted disk; and
[0036] a balancer provided so as to be rotatable integrally with the above-mentioned disk and having a ring-shaped track portion accommodating balance members, wherein
[0037] said balancer is disposed on the same side of the above-mentioned head with respect to the recording face of the above-mentioned disk used as a reference face.
[0038] Therefore, in accordance with the disk drive apparatus of the present invention, even if a mounted unbalanced disk is rotated at high speed, vibration can be suppressed sufficiently, whereby it is possible to attain a low-profile disk drive apparatus capable of carrying out high-rate transfer.
[0039] A disk drive apparatus in accordance with the present invention from another point of view comprises:
[0040] a head for carrying out recording or reproduction on a mounted disk; and a balancer provided so as to be rotatable integrally with the above-mentioned disk and having a ring-shaped track portion accommodating balance members, wherein
[0041] the distance from the outer wall face of the outer periphery of the above-mentioned ring-shaped track portion to the center axis of the above-mentioned ring-shaped track portion is smaller than the distance from the end face of the inner peripheral side of the head being positioned at the innermost track to the center axis of the above-mentioned ring-shaped track portion.
[0042] Therefore, in accordance with the disk drive apparatus of the present invention, even if a mounted unbalanced disk is rotated at high speed, vibration can be suppressed sufficiently, whereby it is possible to attain a low-profile disk drive apparatus capable of carrying out high-rate transfer.
[0043] A disk drive apparatus in accordance with the present invention from another point of view comprises:
[0044] a motor base to which a spindle motor for rotating a disk is secured;
[0045] a sub-base over which the above-mentioned motor base is installed via elastic bodies, and on which a head for carrying out recording or reproduction on the above-mentioned disk is provided movably in the radial direction of the above-mentioned disk; and
[0046] a balancer provided so as to be rotatable integrally with the above-mentioned disk and having a ring-shaped track portion accommodating balance members.
[0047] Therefore, in accordance with the disk drive apparatus of the present invention, the vibration of the disk can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby stable recording or reproduction can be attained, and it is possible to attain a disk drive apparatus capable of carrying out high-speed rotation.
[0048] A disk drive apparatus in accordance with the present invention from another point of view is configured so that the above-mentioned disk is rotated at a frequency higher than the primary resonance frequency of the whirling vibration of the above-mentioned motor base due to the deformation of the above-mentioned elastic bodies.
[0049] Therefore, in accordance with the disk drive apparatus of the present invention, the vibration of the disk can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby stable recording or reproduction can be attained, and it is possible to attain a disk drive apparatus capable of carrying out high-speed rotation.
[0050] A disk drive apparatus in accordance with the present invention from another point of view comprises:
[0051] a balancer provided so as to be rotatable integrally with a mounted disk and having a ring-shaped track portion accommodating spherical bodies, wherein the inner wall face of the outer periphery of the above-mentioned ring-shaped track portion is inclined with respect to the center axis of the above-mentioned ring-shaped track portion.
[0052] Therefore, in accordance with the disk drive apparatus of the present invention, even when the mass imbalance amount of the mounted disk is very large, it is possible to attain a disk drive apparatus having a high vibration suppression effect and being capable of reducing undesirable noise.
[0053] A disk drive apparatus in accordance with the present invention from another point of view comprises:
[0054] a balancer provided so as to be rotatable integrally with a mounted disk and having a ring-shaped track portion accommodating spherical bodies, wherein the sectional shape of the inner wall face of the outer periphery of the above-mentioned ring-shaped track portion is a wedge.
[0055] Therefore, in accordance with the disk drive apparatus of the present invention, vibration due to the mounted unbalanced disk can be suppressed, and undesirable noise caused from the balancer itself can be reduced.
[0056] A disk drive apparatus in accordance with the present invention from another point of view comprises:
[0057] a balancer provided so as to be rotatable integrally with a mounted disk and having a ring-shaped track portion accommodating spherical bodies, wherein the sectional shape of the inner wall face of the outer periphery of the above-mentioned ring-shaped track portion is a curve.
[0058] Therefore, in accordance with the disk drive apparatus of the present invention, even when a disk having a large mass imbalance is mounted, or even when a disk having a small mass imbalance is mounted, vibration can be suppressed securely, and undesirable noise can be reduced.
[0059] A balancer for a disk drive apparatus in accordance with the present invention from another point of view is:
[0060] provided so as to be rotatable integrally with a mounted disk and has a ring-shaped track portion accommodating spherical bodies, wherein the inner wall face of the outer periphery of the above-mentioned ring-shaped track portion is inclined with respect to the center axis of the above-mentioned ring-shaped track portion.
[0061] Therefore, in accordance with the balancer for the disk drive apparatus of the present invention, noise caused from the balancer itself can be suppressed.
[0062] A balancer for a disk drive apparatus in accordance with the present invention from another point of view is:
[0063] provided so as to be rotatable integrally with amounted disk and has a ring-shaped track portion accommodating spherical bodies, wherein the sectional shape of the inner wall face of the outer periphery of the above-mentioned ring-shaped track portion is a wedge.
[0064] Therefore, in accordance with the disk drive apparatus of the present invention, noise caused from the balancer itself can be suppressed.
[0065] A balancer for a disk drive apparatus in accordance with the present invention from another point of view is:
[0066] provided so as to be rotatable integrally with amounted disk and has a ring-shaped track portion accommodating spherical bodies, wherein the sectional shape of the inner wall face of the outer periphery of the above-mentioned ring-shaped track portion is a curve.
[0067] Therefore, in accordance with the balancer for the disk drive apparatus of the present invention, even when a disk having a large mass imbalance is mounted, or even when a disk having a small mass imbalance is mounted, vibration can be suppressed securely, and undesirable noise caused from the balancer itself can be suppressed.
[0068] A balancer for a disk drive apparatus in accordance with the present invention from another point of view is:
[0069] provided so as to be rotatable integrally with amounted disk and has a ring-shaped track portion accommodating balance members, wherein
[0070] the balancer satisfies the relationship of:
h.gtoreq.f.sup.2.times..vertline.A-Z.vertline.,
[0071] when the total mass of the above-mentioned balance members is M [g], the distance to the center of gravity of the total of the above-mentioned balance members from the center axis of the above-mentioned ring-shaped track portion is T [cm], a balance amount Z [gcm] is represented by:
Z=M.times.T,
[0072] when the maximum rotation frequency of the above-mentioned disk is f [Hz], the maximum of the mass imbalance amount of the above-mentioned disk is A [gcm], and a constant is h.
[0073] Therefore, in accordance with the balancer for the disk drive apparatus of the present invention, even if the disk is rotated at high speed, vibration due to the mass imbalance of the disk can be suppressed securely, whereby it is possible to attain a disk drive apparatus capable of carrying out high-rate transfer.
[0074] A balancer for a disk drive apparatus in accordance with the present invention from another point of view is:
[0075] provided so as to be rotatable integrally with amounted disk and has a ring-shaped track portion accommodating spherical bodies, wherein
[0076] the balancer satisfies the relationship of:
h.gtoreq.f.sup.2.times..vertline.A-Z.vertline.,
[0077] when the radius of the above-mentioned spherical body is r [cm], the radius of the inner wall face of the outer periphery of the above-mentioned ring-shaped portion is S [cm], the number of the above-mentioned spherical bodies is n, the specific gravity of the above-mentioned spherical body is .rho., and a balance amount Z [gcm] is represented by:
Z={fraction (4/3)}.pi.r.sup.2.rho.(S-r).sup.2.times.sin[n sin.sup.-1{r/(S-r)}],
[0078] when the maximum rotation frequency of the above-mentioned disk is f [Hz], the maximum of the mass imbalance amount of the above-mentioned disk is A [gcm], and a constant is h.
[0079] In a balancer for a disk drive apparatus in accordance with the present invention, the above-mentioned constant h may be represented by:
h=fo.sup.2.times.Ao,
[0080] in the case when the maximum allowable rotation frequency wherein vibration becomes an allowable value or less is fo [Hz] at the time when a disk having a mass imbalance amount Ao [gcm] is rotated in a condition wherein the above-mentioned balance amount Z=0 [gcm].
[0081] In a balancer for a disk drive apparatus in accordance with the present invention, it is preferable that the diameter of a disk to be mounted is 12 [cm] or less, and that the above-mentioned constant h is 8100.
[0082] Therefore, in accordance with the balancer for the disk drive apparatus of the present invention, even if the disk is rotated at high speed, vibration due to the mass imbalance of the disk can be suppressed securely, whereby it is possible to attain a disk drive apparatus capable of carrying out high-rate transfer.
[0083] Furthermore, in order to attain the above-mentioned objects, the disk drive apparatus of the present invention is a device wherein a balancer having a ring-shaped track divided into plural tracks and balance members movable along the divided tracks respectively is provided so as to be rotatable integrally with a disk; and concrete means thereof are described below.
[0084] A disk drive apparatus in accordance with the present invention comprises a balancer having a plurality of arc-shaped tracks and balance members provided so as to be movable on the above-mentioned arc-shaped tracks.
[0085] Therefore, in accordance with the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby stable recording or reproduction can be attained, and it is possible to attain a disk drive apparatus capable of carrying out high-speed rotation without losing vibration-resistant and impact-resistant characteristics.
[0086] A disk drive apparatus in accordance with the present invention from another point of view comprises a balancer having division means for dividing a ring-shaped track into plural tracks, arc-shaped tracks formed by the above-mentioned division means, and balance members provided so as to be movable on the above-mentioned arc-shaped tracks.
[0087] Therefore, in accordance with the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby stable recording or reproduction can be attained, and it is possible to attain a disk drive apparatus capable of carrying out high-speed rotation without losing vibration-resistant and impact-resistant characteristics.
[0088] In a disk drive apparatus in accordance with the present invention, the above-mentioned division means may be configured to absorb shock.
[0089] Therefore, in accordance with the disk drive apparatus of the present invention, noise caused from the balancer itself can be suppressed.
[0090] In a disk drive apparatus in accordance with the present invention, in at least portions of the above-mentioned arc-shaped tracks, the distance from the rotation axis of a disk to at least one track increases in the rotation direction of the above-mentioned disk.
[0091] Therefore, in accordance with the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby stable recording or reproduction can be attained, and it is possible to attain a disk drive apparatus capable of carrying out high-speed rotation without losing vibration-resistant and impact-resistant characteristics.
[0092] In a disk drive apparatus in accordance with the present invention, the above-mentioned division means may be configured to be held so as to be rotatable with respect to the ring-shaped tracks.
[0093] Therefore, in accordance with the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby stable recording or reproduction can be attained, and it is possible to attain a disk drive apparatus capable of carrying out high-speed rotation without losing vibration-resistant and impact-resistant characteristics.
[0094] In a disk drive apparatus in accordance with the present invention, the above-mentioned balance members may be formed of a magnetic material, and magnetic field generation means having magnetic poles may be disposed in the vicinity of the above-mentioned division means.
[0095] Therefore, in accordance with the disk drive apparatus of the present invention, noise caused from the balancer itself can be suppressed regardless of the high speed or low speed of disk rotation.
[0096] In a disk drive apparatus in accordance with the present invention, the above-mentioned balance members may be formed of a magnetic material, magnetic field generation means having magnetic poles may be disposed in the vicinity of the above-mentioned division means, and shock-absorbing members may be provided in the above-mentioned ring-shaped tracks at positions opposite to the positions of the magnet poles of the above-mentioned magnetic field generation means.
[0097] Therefore, in accordance with the disk drive apparatus of the present invention, noise caused from the balancer itself can be suppressed regardless of the high speed or low speed of disk rotation.
[0098] In a disk drive apparatus in accordance with the present invention, the above-mentioned balance members may be formed of a magnetic material, magnetic field generation means for magnetically attracting the above-mentioned balance members may be provided, and the connection portions between the above-mentioned division means and the above-mentioned ring-shaped tracks may be formed of curves.
[0099] Therefore, in accordance with the disk drive apparatus of the present invention, noise caused from the balancer itself can be suppressed regardless of the high speed or low speed of disk rotation.
[0100] In a disk drive apparatus in accordance with the present invention, the above-mentioned ring-shaped tracks may be plural in number.
[0101] Therefore, in accordance with the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk.
[0102] A balancer for a disk drive apparatus in accordance with the present invention has a plurality of arc-shaped tracks and balance members provided so as to be movable on the above-mentioned arc-shaped tracks.
[0103] Therefore, in accordance with the balancer for the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby vibration and noise from the balancer can be suppressed.
[0104] A balancer for a disk drive apparatus in accordance with the present invention from another point of view has division means for dividing a ring-shaped track into plural tracks, arc-shaped tracks formed by the above-mentioned division means and balance members provided so as to be movable on the above-mentioned arc-shaped tracks.
[0105] Therefore, in accordance with the balancer for the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby vibration and noise from the balancer can be suppressed.
[0106] In a balancer for a disk drive apparatus in accordance with the present invention, the above-mentioned division means may be configured to absorb shock.
[0107] Therefore, in accordance with the balancer for the disk drive apparatus of the present invention, noise caused from the balancer itself can be suppressed.
[0108] In a balancer for a disk drive apparatus in accordance with the present invention, in at least portions of the above-mentioned arc-shaped tracks, the distance from the rotation axis of a disk to at least one track increases in the rotation direction of the disk.
[0109] Therefore, in accordance with the balancer for the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby vibration and noise from the balancer can be suppressed.
[0110] In a balancer for a disk drive apparatus in accordance with the present invention, the above-mentioned division means may be configured to be held so as to be rotatable with respect to the above-mentioned ring-shaped tracks.
[0111] Therefore, in accordance with the balancer for the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby vibration and noise from the balancer can be suppressed.
[0112] In a balancer for a disk drive apparatus in accordance with the present invention, the above-mentioned balance members maybe formed of a magnetic material, and magnetic field generation means for magnetically attracting the above-mentioned balance members may be provided.
[0113] Therefore, in accordance with the balancer for the disk drive apparatus of the present invention, noise caused from the balancer itself can be suppressed regardless of the high speed or low speed of disk rotation.
[0114] In a balancer for a disk drive apparatus in accordance with the present invention, the above-mentioned balance members may be formed of a magnetic material, magnetic field generation means for magnetically attracting the above-mentioned balance members may be provided, and the connection portions between the above-mentioned division means and the above-mentioned ring-shaped tracks may be formed of curves.
[0115] Therefore, in accordance with the balancer for the disk drive apparatus of the present invention, noise caused from the balancer itself can be suppressed regardless of the high speed or low speed of disk rotation.
[0116] A clamper for a disk drive apparatus in accordance with the present invention comprises a balancer having a plurality of arc-shaped tracks and balance members provided so as to be movable on the above-mentioned arc-shaped tracks, and is configured to rotatably hold a disk mounted on a turntable.
[0117] Therefore, in accordance with the clamper for the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby vibration and noise from the balancer can be suppressed.
[0118] A spindle motor for a disk drive apparatus in accordance with the present invention comprises a balancer having a plurality of arc-shaped tracks and balance members provided so as to be movable on the above-mentioned arc-shaped tracks.
[0119] Therefore, in accordance with the spindle motor for the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby vibration and noise from the balancer can be suppressed.
[0120] A spindle motor for a disk drive apparatus in accordance with the present invention from another point of view comprises a balancer having a plurality of arc-shaped tracks and balance members provided so as to be movable on the above-mentioned arc-shaped tracks, wherein said balancer is provided so as to be rotatable integrally with a rotor.
[0121] Therefore, in accordance with the spindle motor for the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby vibration and noise from the balancer can be suppressed.
[0122] A spindle motor for a disk drive apparatus in accordance with the present invention from another point of view comprises a balancer having a plurality of arc-shaped tracks and balance members provided so as to be movable on the above-mentioned arc-shaped tracks, wherein said balancer is provided so as to be rotatable integrally with a spindle shaft.
[0123] Therefore, in accordance with the spindle motor for the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby vibration and noise from the balancer can be suppressed.
[0124] A turntable for a disk drive apparatus in accordance with the present invention comprises a balancer having a plurality of arc-shaped tracks and balance members provided so as to be movable on the above-mentioned arc-shaped tracks, wherein a disk is mounted thereon and the above-mentioned disk is supported rotatably.
[0125] Therefore, in accordance with the spindle motor for the disk drive apparatus of the present invention, the vibration of the sub-base can be suppressed securely regardless of the magnitude of the mass imbalance of the disk, whereby vibration and noise from the balancer can be suppressed.
[0126] In order to solve the above-mentioned problems, the disk drive apparatus of the present invention relates to a turntable and a clamper used as means for holding a disk and rotating it integrally; and concrete means thereof are described below.
[0127] A disk drive apparatus in accordance with the present invention comprises disk support means for supporting at least one side of the above-mentioned disk by using four or more projections, wherein the tips of the above-mentioned projections are substantially on the same plane.
[0128] Therefore, in accordance with the disk drive apparatus of the present invention, the disk can be held securely; and in the case when the disk is rotated at high speed, vibration and noise due to the imbalance, such as a face deflection, of the disk can be reduced, whereby it is possible to attain a disk drive apparatus capable of carrying out high-rate data transfer.
[0129] A disk drive apparatus in accordance with the present invention from another point of view comprises:
[0130] a turntable on which a disk is mounted; and
[0131] a clamper having four or more projections, the tips of which are substantially on the same plane, wherein the above-mentioned disk is held between the above-mentioned projections and the above-mentioned turntable.
[0132] Therefore, in accordance with the disk drive apparatus of the present invention, the disk can be held securely by using the clamper; and in the case when the disk is rotated at high speed, vibration and noise due to the imbalance, such as a face deflection, of the disk can be reduced, whereby stable recording/reproduction can be attained, and it is possible to attain a disk drive apparatus capable of carrying out high-rate data transfer.
[0133] A disk drive apparatus in accordance with the present invention from another point of view comprises:
[0134] a turntable for supporting a disk by using four or more projections, the tips of which are substantially on the same plane; and
[0135] a clamper used with the above-mentioned turntable to hold the above-mentioned disk therebetween.
[0136] Therefore, in accordance with the disk drive apparatus of the present invention, the disk can be held securely by using the turntable, and vibration and noise in the case when the disk is rotated at high speed can be reduced.
[0137] A disk drive apparatus in accordance with the present invention from another point of view comprises:
[0138] a turntable for supporting a disk by using four or more projections, the tips of which are substantially on the same plane; and
[0139] a clamper having four or more projections and holding the above-mentioned disk between the projections and the projections of the above-mentioned turntable.
[0140] Therefore, in accordance with the disk drive apparatus of the present invention, the disk can be held securely between the turntable and the clamper, and vibration and noise in the case when the disk is rotated at high speed can be reduced.
[0141] In the disk drive apparatus of the present invention, in addition to the means of the above-mentioned disk drive apparatus, the projections of the above-mentioned turntable and the projections of the above-mentioned clamper may be provided so as to be opposite to each other.
[0142] Therefore, in accordance with the disk drive apparatus of the present invention, the disk can be held more securely between the turntable and the clamper, and vibration and noise in the case when the disk is rotated at high speed can be reduced.
[0143] A disk drive apparatus of the present invention, in addition to the means of the above-mentioned disk drive apparatus, may comprise:
[0144] a sub-base to which a disk rotation drive motor is secured;
[0145] a main base over which the above-mentioned sub-base is installed via elastic bodies; and
[0146] a balancer having a ring-shaped track portion accommodating plural spherical bodies therein and provided so as to be rotatable integrally with a disk.
[0147] Therefore, in accordance with the disk drive apparatus of the present invention, the balls of the balancer can be stabilized, whereby imbalance due to the eccentricity of the disk at the time of rotation can be reduced securely.
[0148] In the disk drive apparatus of the present invention, the above-mentioned projections may be disposed on a circumference being coaxial with the rotation center of a disk.
[0149] In the disk drive apparatus of the present invention, the above-mentioned projections may be disposed on circumferences having different diameters and being coaxial with the rotation center of a disk.
[0150] Therefore, in accordance with the disk drive apparatus of the present invention, vibration and noise in the case when the disk being held is rotated at high speed can be reduced further.
[0151] A disk drive apparatus in accordance with the present invention from another point of view comprises:
[0152] a turntable provided with an elastic body on a face thereof on which a disk used as a recording medium is mounted; and
[0153] a clamper having four or more projections, the tips of which are substantially on the same plane, and holding the above-mentioned disk between the above-mentioned projections and the above-mentioned turntable.
[0154] Therefore, in accordance with the disk drive apparatus of the present invention, the unevenness on the disk mounting face of the turntable can be improved easily, and vibration and noise in the case when the disk is rotated at high speed can be reduced.
[0155] A disk drive apparatus in accordance with the present invention from another point of view comprises:
[0156] a turntable for supporting a disk by using four or more projections, the tips of which are substantially on the same plane; and
[0157] a clamper provided with an elastic body on a face thereof for holding the above-mentioned disk to hold the above-mentioned disk between the above-mentioned elastic body and the above-mentioned turntable.
[0158] Therefore, in accordance with the disk drive apparatus of the present invention, the unevenness on the disk holding face of the clamper can be improved easily, and vibration and noise in the case when the disk is rotated at high speed can be reduced.
[0159] A disk drive apparatus in accordance with the present invention from another point of view comprises:
[0160] a turntable provided with an elastic body on a face thereof on which a disk used as a recording medium is mounted; and
[0161] a clamper provided with an elastic body on a face thereof for holding the above-mentioned disk to hold the above-mentioned disk between the above-mentioned elastic body and the above-mentioned turntable.
[0162] Therefore, in accordance with the disk drive apparatus of the present invention, the unevenness on the disk mounting face of the turntable and the disk holding face of the clamper can be improved easily, and vibration and noise in the case when the disk is rotated at high speed can be reduced.
[0163] While the novel features of the invention are set forth particularly in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, along with other objects and features thereof, from the following detailed description taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0164] FIG. 1 is a side sectional view showing the vicinity of the spindle motor 2 of the disk drive apparatus in accordance with the first embodiment of the present invention.
[0165] FIG. 2 is a plan sectional view showing only the spherical body balancer 22a provided integrally with the rotor 80 of the disk drive apparatus in accordance with the first embodiment of FIG. 1.
[0166] FIG. 3 is a graph showing the measured values of the vibration acceleration of a sub-base 6 in order to show the effects of the first embodiment of the present invention.
[0167] FIG. 4 is a side sectional view showing the vicinity of the spindle motor 2 of the disk drive apparatus in accordance with the second embodiment of the present invention.
[0168] FIG. 5 is a side sectional view showing the vicinity of the spindle motor 2 of the disk drive apparatus in accordance with the third embodiment of the present invention.
[0169] FIG. 6 is a sectional view showing the vicinity of the balancer 22c provided integrally with the rotor 80 of the disk drive apparatus in accordance with the fourth embodiment of the present invention.
[0170] FIG. 7 is a sectional view showing the vicinity of the balancer 22d provided integrally with the rotor 80 of the disk drive apparatus in accordance with the fifth embodiment of the present invention.
[0171] FIG. 8 is a sectional view showing the vicinity of the balancer 22e provided integrally with the rotor 80 of the disk drive apparatus in accordance with the sixth embodiment of the present invention.
[0172] FIG. 9 is a perspective view showing a conventional disk drive apparatus.
[0173] FIG. 10 is a side sectional view showing the vicinity of the spindle motor of the conventional disk drive apparatus.
[0174] FIG. 11 is a view illustrating the movement of the balls of a balancer in the conventional disk drive apparatus.
[0175] FIG. 12 is a side sectional view showing the vicinity of the spindle motor of the disk drive apparatus in accordance with the seventh embodiment of the present invention.
[0176] FIG. 13 is a plan sectional view illustrating forces acting on the balls of a balancer of the disk drive apparatus in accordance with the seventh embodiment of the present invention.
[0177] FIG. 14 is a view illustrating the movement of the balls of the balancer in the case when a disk having a mass imbalance is rotated at high speed by the disk drive apparatus in accordance with the seventh embodiment of the present invention.
[0178] FIG. 15 is a view illustrating the movement of the balls of the balancer in the case when a uniform disk having no mass imbalance is rotated at high speed by the disk drive apparatus in accordance with the seventh embodiment of the present invention.
[0179] FIG. 16 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the seventh embodiment of the present invention.
[0180] FIG. 17 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the seventh embodiment of the present invention.
[0181] FIG. 18 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the seventh embodiment of the present invention.
[0182] FIG. 19 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the seventh embodiment of the present invention.
[0183] FIG. 20 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the seventh embodiment of the present invention.
[0184] FIG. 21 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the seventh embodiment of the present invention.
[0185] FIG. 22 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the seventh embodiment of the present invention.
[0186] FIG. 23 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the seventh embodiment of the present invention.
[0187] FIG. 24 shows a plan sectional view (a) and a vertical sectional view (b) showing the configurations of other two kinds of balancers of the disk drive apparatus in accordance with the seventh embodiment of the present invention.
[0188] FIG. 25 is a plan sectional view showing the configuration of a balancer of the disk drive apparatus in accordance with the eighth embodiment of the present invention.
[0189] FIG. 26 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the eighth embodiment of the present invention.
[0190] FIG. 27 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the eighth embodiment of the present invention.
[0191] FIG. 28 is a plan sectional view showing the configuration of a balancer of the disk drive apparatus in accordance with the ninth embodiment of the present invention.
[0192] FIG. 29 is a view illustrating a problem in the balancers of the disk drive apparatuses in accordance with the seventh embodiment of the present invention.
[0193] FIG. 30 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the ninth embodiment of the present invention.
[0194] FIG. 31 is a view illustrating the movement of the balls of the balancer in the case when a disk having a mass imbalance is rotated at high speed by the disk drive apparatus in accordance with the 10th embodiment of the present invention.
[0195] FIG. 32 is a view illustrating the movement of the balls of the balancer in the case when a uniform disk having no mass imbalance is rotated at high speed by the disk drive apparatus in accordance with the 10th embodiment of the present invention.
[0196] FIG. 33 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the 10th embodiment of the present invention.
[0197] FIG. 34 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the 10th embodiment of the present invention.
[0198] FIG. 35 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the 10th embodiment of the present invention.
[0199] FIG. 36 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the 10th embodiment of the present invention.
[0200] FIG. 37 is a plan sectional view showing the configuration of another balancer of the disk drive apparatus in accordance with the 10th embodiment of the present invention.
[0201] FIG. 38 is a view illustrating the movement of the balls of the balancer in the case when a disk having a mass imbalance is rotated at high speed by the disk drive apparatus in accordance with the 11th embodiment of the present invention.
[0202] FIG. 39 is a view illustrating the movement of the balls of the balancer in the case when a disk having a mass imbalance is rotated at high speed by the disk drive apparatus in accordance with the 11th embodiment of the present invention.
[0203] FIG. 40 is a plan sectional view showing the configuration of a balancer of the disk drive apparatus in accordance with the 12th embodiment of the present invention.
[0204] FIG. 41 is a plan sectional view showing the configuration of a balancer of the disk drive apparatus in accordance with the 13th embodiment of the present invention.
[0205] FIG. 42 is a perspective view showing a condition wherein a disk 501 is mounted on the conventional disk drive apparatus and secured by a clamper 581.
[0206] FIG. 43 is a side sectional view showing the vicinity of the spindle motor 502 of the conventional disk drive apparatus.
[0207] FIG. 44 is a side sectional view showing the vibration of the disk 501 in the case when the disk 501 is mounted on the turntable 582 of the conventional disk drive apparatus and rotated.
[0208] FIG. 45 is a plan view showing the two-division mode of the vibration of the disk 501 of the conventional disk drive apparatus.
[0209] FIG. 46 is a plan view showing the four-division mode of the vibration of the disk 501 of the conventional disk drive apparatus.
[0210] FIG. 47 is a plan view showing the six-division mode of the vibration of the disk 501 of the conventional disk drive apparatus.
[0211] FIG. 48 is a plan view showing the eight-division mode of the vibration of the disk 501 of the conventional disk drive apparatus.
[0212] FIG. 49 is a graph showing the result of the vibration analysis of the disk 501 of the conventional disk drive apparatus.
[0213] FIG. 50 shows a side sectional view of the clamper 581(a) of the conventional disk drive apparatus and a reverse-side view (b) of the clamper 581 showing the face of the clamper 581 making contact with the disk 501.
[0214] FIG. 51 is a side sectional view showing the difference in the vibration of the disk 501 depending on the difference in the face of the clamper 581 of the conventional disk drive apparatus making contact with the disk 501.
[0215] FIG. 52 is a perspective view showing a condition wherein the disk 501 is mounted on the disk drive apparatus of the 14 embodiment of the present invention, and secured with a clamper 541.
[0216] FIG. 53 is a side sectional view showing the vicinity of the spindle motor 502 of the disk drive apparatus in accordance with the 14th embodiment of the present invention.
[0217] FIG. 54 shows a side sectional view (a) and a reverse-side view (b) showing the clamper 541 of the disk drive apparatus in accordance with the 14th embodiment of the present invention.
[0218] FIG. 55 shows a side sectional view (a) and a reverse-side view (b) showing another clamper 541 of the disk drive apparatus in accordance with the 14th embodiment of the present invention.
[0219] FIG. 56 shows a side sectional view (a) and a reverse-side view (b) showing another clamper 541 of the disk drive apparatus in accordance with the 14th embodiment of the present invention.
[0220] FIG. 57 is a partially enlarged view showing the shapes of the clamper projections 551 provided on the clamper 541 of the disk drive apparatus in accordance with the 14th embodiment of the present invention.
[0221] FIG. 58 is a reverse-side view showing the dispositions of the clamper projections 551 provided on another clamper 541 of the disk drive apparatus in accordance with the 14th embodiment of the present invention.
[0222] FIG. 59 shows a side sectional view (a) and a reverse-side view (b) showing the vicinity of the clamper 541 of the disk drive apparatus in accordance with the 15th embodiment of the present invention.
[0223] FIG. 60 shows a side sectional view (a) and a reverse-side view (b) showing the vicinity of the clamper 413 of the disk drive apparatus in accordance with the 16th embodiment of the present invention.
[0224] FIG. 61 is a perspective view showing the positioning mechanism of the disk drive apparatus in accordance with the 16th embodiment of the present invention.
[0225] FIG. 62 shows side sectional views showing the vicinity of the clamper 414 of the disk drive apparatus in accordance with the 17th embodiment of the present invention, showing conditions at rest (a) and at the time of rotation (b).
[0226] FIG. 63 shows plan sectional views showing the clamper 541 of the disk drive apparatus in accordance with the 17th embodiment of the present invention, showing conditions at rest (a) and at the time of rotation (b) and (c).
[0227] FIG. 64 is a side sectional view showing the vicinity of the clamper 414 of the disk drive apparatus in accordance with the 17th embodiment of the present invention.
[0228] FIG. 65 shows a side sectional view (a) and a reverse-side view (b) showing the vicinity of a clamper 415 of the disk drive apparatus in accordance with the 18th embodiment of the present invention.
[0229] FIG. 66 is a side sectional view showing the magnitude of disk deformation and vibration depending on the disk securing method of the clamper in the disk drive apparatus.
[0230] FIG. 67 shows a side sectional view (a) and a reverse-side view (b) showing the vicinity of another clamper 415 of the disk drive apparatus in accordance with the 18th embodiment of the present invention.
[0231] FIG. 68 shows a side sectional view (a) and a reverse-side view (b) showing the vicinity of another clamper 415 of the disk drive apparatus in accordance with the 18th embodiment of the present invention.
[0232] FIG. 69 shows a side sectional view (a) of the vicinity of a clamper 541 and a reverse-side view (b) of the clamper 541, showing the positional relationship between the dispositions of the clamper projections 551 provided on the clamper 541 of the disk drive apparatus in accordance with the 19th embodiment of the present invention and a turntable-use rubber sheet 571 stuck to the turntable 216.
[0233] FIG. 70 shows a side sectional view (a) of the vicinity of another 416 clamper 416 and a reverse-side view (b) of the clamper 416, showing the positional relationship between a clamper-use rubber sheet 572 stuck to the clamper 416 of the disk drive apparatus in accordance with the 19th embodiment of the present invention and the dispositions of the clamper projections 552 provided on the turntable 212.
[0234] FIG. 71 shows a side sectional view (a) of the vicinity of another 416 clamper 416 and a reverse-side view (b) of the clamper 416, showing the positional relationship between the clamper-use rubber sheet 572
stuck to the clamper 416 of the disk drive apparatus in accordance with the 19th embodiment of the present invention and the turntable-use rubber sheet 571 stuck to the turntable 216.
[0235] FIG. 72 is a perspective view showing the conventional disk drive apparatus.
[0236] FIG. 73 is a side sectional view showing the vicinity of the spindle motor 502 of the conventional disk drive apparatus.
[0237] It will be recognized that some or all of the Figures are schematic representations for purposes of illustration and do not necessarily depict the actual relative sizes or locations of the elements shown.
BEST MODE FOR CARRYING OUT THE INVENTION
First Embodiment
[0238] A disk drive apparatus in accordance with a first embodiment of the present invention will be described below referring to the accompanying drawings.
[0239] FIG. 1 is a side sectional view showing the vicinity of the spindle motor 2 of the disk drive apparatus in accordance with the first embodiment of the present invention. FIG. 2 is a plan sectional view showing only the hollow ring-shaped portion 23 used as a ring-shaped track portion provided so as to be rotatable integrally with the rotor 80
of the first embodiment of the present invention. FIG. 3 shows the measured values of the vibration acceleration of a sub-base 6 in order to show the effects of the disk drive apparatus of the first embodiment of the present invention.
[0240] In the disk drive apparatus of the first embodiment, the disk 1
mounted on a turntable 110 is configured so as to be rotated by the spindle motor 2, and a head (not shown) is used to read data or write data. In addition, in the disk drive apparatus of the first embodiment, a head drive mechanism comprising a rack, a pinion and the like, which converts a rotation motion into a linear motion, and a head drive motor are provided as shown in the above-mentioned FIG. 72. The head is configured so as to be moved in the radial direction of the disk 1 by this head drive mechanism. The spindle motor 2, the head drive motor, the head drive mechanism and the like are mounted on the sub-base 6. Vibration and impact transmitted from outside the device to the sub-base 6 are dampened by insulators 7 (elastic bodies). The sub-base 6 is mounted on a main base 8 via these insulators 7. The main unit of the disk drive apparatus shown in FIG. 1 is configured so as to be built in a computer or the like via a frame (not shown) installed on the main base 8.
[0241] In FIG. 1, the turntable 110 is secured to the shaft 21 of the spindle motor 2 and rotatably supports the clamp area 11 of the disk 1. Inside the boss 14 formed on the turntable 110, a positioning ball 116
making contact with the corner portion of the clamp hole 12 of the disk 1
by virtue of a pressing means 113, such as a coil spring, is built in. In this way, the disk 1 is securely disposed at a predetermined position on the turntable 110 by the pressing operation of the positioning ball 116.
[0242] As described above, in the disk drive apparatus of the first embodiment, the disk 1 on the turntable 110 is pressed and secured by the positioning ball 116, thereby being configured so as to be rotated coaxially together with the rotor 80 of the spindle motor 2.
[0243] As shown in FIG. 1, the disk drive apparatus of the first embodiment comprises a spherical body balancer 22arotatable integrally with the rotor 80 of the spindle motor 2. FIG. 2 is a plan sectional view showing only the spherical body balancer 22a.
[0244] As shown in FIGS. 1 and 2, the spherical body balancer 22aof the first embodiment comprises a hollow ring-shaped portion 23 used as a ring-shaped track portion having a ring-shaped passage provided coaxially with the spindle shaft 21 of the spindle motor 2, and a plurality of spherical bodies 24 movably accommodated inside the passage of the hollow ring-shaped portion 23.
[0245] As described above, in the condition wherein the disk 1 is clamped on the turntable 110 by the positioning ball 116, by making the positioning ball 116 contact with the corner portion of the clamp hole 12, the disk 1 is positioned and disposed at the predetermined position, and held on the turntable 110 by the pressing force of the coil spring used as the pressing means 113, just as in the case of the conventional disk drive apparatus shown in the above-mentioned FIG. 73. The disk 1
held in this way is rotated integrally with the turntable 110, the rotor 80 and the spherical body balancer 22a by the spindle motor 2.
[0246] Furthermore, the disk drive apparatus of the first embodiment uses the insulators (elastic bodies) 7 having low rigidity to connect the sub-base 6 to the main base 8. In the disk drive apparatus of the first embodiment, the primary resonance frequency of the mechanical vibration of the sub-base 6 due to the deformation of the insulators 7, having the direction parallel to the recording face of the disk 1, is set lower than the rotation frequency of the disk 1. More specifically, in the first embodiment, the rotation frequency of the disk 1 is set at about 100 Hz, and both the primary resonance frequency of the vibration of the sub-base 6 in the direction (access direction) wherein the head is driven by the head drive mechanism and the primary resonance frequency of the vibration of the sub-base 6 in the direction perpendicular thereto are set at about 60 Hz.
[0247] In the disk drive apparatus of the first embodiment of the present invention configured as described above, operation in the case when the disk 1 having a large mass imbalance amount is rotated at 100 Hz will be described referring to FIGS. 1 and 2.
[0248] First, a centrifugal force F (referred to as an imbalance force) acts on the center of gravity G1 of the disk 1, and the direction of the action rotates as the disk 1 rotates. This imbalance force F deforms the insulators 7, and the sub-base 6 and the whole of the components mounted on the sub-base 6 whirl at the rotation frequency of the disk 1. In the first embodiment, the primary resonance frequency (about 60 Hz) of the sub-base 6 due to the deformation of the insulators 7 is set lower than the rotation frequency (about 100 Hz) of the disk 1. Therefore, the displacement direction of the sub-base 6 and the action direction of the imbalance force F are nearly opposite to each other at all times.
[0249] Therefore, as shown in FIG. 2, the whirling center axis P1 of the disk 1 rotating on the sub-base 6 is disposed between the center of gravity G1 of the disk 1 on which the imbalance force F acts and the rotation center axis P0 of the spindle motor.
[0250] In the above-mentioned condition, since the hollow ring-shaped portion 23 integrally provided with the rotor 80 is positioned so as to be coaxial with the rotation center axis P0 of the spindle motor 2, the center of the hollow ring-shaped portion 23, i.e., the center P2 of the inner wall face 25 of the outer periphery thereof, coincides with the rotation center axis P0 of the spindle motor 2. Therefore, the hollow ring-shaped portion 23 carries out whirling operation around the whirling center axis P1.
[0251] During this whirling operation, a centrifugal force q acts on the spherical body 24 (a spherical body positioned at the upper portion in FIG. 2, for example) accommodated in the hollow ring-shaped portion 23 in the direction of connecting the whirling center axis P1 to the center of gravity of the spherical body 24. In addition, since the movement of the spherical body 24 is restricted by the inner wall face 25 of the outer periphery of the hollow ring-shaped portion 23, a reaction N from the inner wall face 25 of the outer periphery acts on the spherical body 24. This reaction N from the inner wall face 25 of the outer periphery acts toward the center P2 of the inner wall face 25 of the outer periphery. Therefore, a movement force R, i.e., the resultant force of the centrifugal force q and the reaction N, acts on the spherical body 24 in the direction of the tangent of the circle centered at the center P2 of the inner wall face 25 of the outer periphery, passing through the center of gravity of the spherical body 24, and being away from the whirling center axis P1. By this movement force R, the spherical body 24 is moved along the inner wall face 25 of the outer periphery, that is, is moved in the direction nearly opposite to the center of gravity G1 of the disk 1
with respect to the whirling center axis P1, whereby the spherical body 24 and the other spherical bodies 24 gather together at the position nearly opposite to the center of gravity G1.
[0252] As a result, when the component of the centrifugal force q, acting on each of the spherical bodies 24 having gathered in the same direction of the imbalance force, is a balance force zk, the imbalance force F due to the rotation of the disk 1 is canceled by the resultant force Zn of these balance forces zk. As a result, the force acting on the sub-base 6
decreases. Therefore, the vibration of the sub-base 6 occurring in the case when an unbalanced disk 1 is rotated is suppressed securely.
[0253] In the first embodiment of the present invention, since the imbalance force F is canceled by the balance force Zn acting on the spherical bodies 24 having gathered as described above, the whirling radius X1 of the center P2 of the inner wall face 25 of the outer periphery around the center axis P1 becomes nearly zero, whereby the center P2 of the inner wall face 25 of the outer periphery and the whirling center axis P1 shown in FIG. 2 nearly coincide with each other.
[0254] As shown in FIG. 2, when the radius of the spherical body 24 is r [cm], the specific gravity thereof is .rho., the number of pieces thereof is n, the radius of the inner wall face 25 of the outer periphery of the hollow ring-shaped portion 23 is S [cm], and rotational angular velocity is .omega. [rad/sec], the centrifugal force q acting on each spherical body 24 is represented by:
q={fraction (4/3)}.pi.r.sup.3.rho.(S-r).omega..sup.2 (1).
[0255] At this time, when the line connecting the center of gravity G1 of the disk 1 to the center P2 of the inner wall face 25 of the outer periphery is defined as a reference line in FIG. 2, and the angle from the reference line of the spherical body 24 positioned first on the upper side of the reference line is a as shown in FIG. 2, it is represented by:
.alpha.=sin.sup.-1{r/(S-r)} (2).
[0256] The angle .alpha.k between the reference line and the position of the spherical body 24 located at the kth position from the reference line is represented by:
.alpha.k=(2k-1) .alpha. (3).
[0257] And the balance force zk acting on the spherical body 24 located at the kth position from the reference line is represented by:
zk=q cos(k) (4).
[0258] Therefore, when the number n of the spherical bodies is an even number, and n=2v, the resultant force Zn of the balance forces zk individually acting on the gathering spherical bodies 24 is represented by:
Zn=2q{cos .alpha.+cos 3.alpha.+. . . +cos(2v-1).alpha.} (5).
[0259] When this expression is modified by using the above-mentioned expressions (2), (3) and (4):
Zn=q.times.1/2.times.sin{2v sin.sup.-1(r/S-r)}/(r/S-r).
[0260] This expression is obtained. When the expression (1) is substituted into this expression, when v is replaced with n, and when the expression is arranged:
Zn={fraction (4/3)}.pi.r.sub.2.rho.(S-r).sub.2.times.sin[n sin.sub.-1{r/(S-r)}].omega..sub.2.
[0261] This expression is obtained. When the ratio of the balance force Zn with respect to the square of the rotational angular velocity .omega. is a balance amount Z [gcm]:
Z=Zn/.omega..sup.2.
[0262] This expression is obtained. As a result:
Z={fraction (4/3)}.pi.r.sup.2.rho.(S-r).sup.2.times.sin[n sin.sup.-1{r/(S-r)}] (6).
[0263] This expression is obtained.
[0264] After all, an imbalance force in proportion to the product of the difference between the balance amount Z due to the spherical bodies 24
and the mass imbalance amount A of the disk 1, that is, the residual mass imbalance amount .vertline.A-Z.vertline., and the square of the rotation frequency f [Hz] of the disk 1 acts on the sub-base 6. Therefore, the vibration of the sub-base 6 can be suppressed by making f.sup.2.vertline.A-Z.vertline. sufficiently small.
[0265] In the disk drive apparatus of the first embodiment of the present invention, h is used as a predetermined constant; the radius r [cm], the specific weight .rho. and the number of the spherical bodies 24, and the radius S [cm] of the inner wall face 25 of the outer periphery of the hollow ring-shaped portion 23 are set so that the balance amount Z represented by the expression (6) satisfies the following expression:
h.gtoreq.f.sup.2.times..vertline.A-Z.vertline. (7).
[0266] Herein, the constant h means the magnitude of f.sup.2.times.A at the time when the magnitude of the vibration of the sub-base 6 is limited to the maximum allowable amount wherein stable recording or reproduction can be attained. For example, the maximum mass imbalance amount A of a 12
cm diameter CD-ROM disk is about 1 gcm; in the conventional disk drive apparatus, when a disk having a mass imbalance amount A of 1 gcm is rotated, the limit rotation frequency thereof is about 90 Hz; when the disk was rotated at 100 Hz or more, stable reproduction was unable to be carried out, or noise increased to an undesirable level. In other words, in the case of a CD-ROM disk drive apparatus, the maximum allowable value hc represented by f.sup.2.times.A becomes:
hc=90.sup.2.times.1=8100 gcm/sec.sup.2.
[0267] In the disk drive apparatus of the first embodiment of the present invention, in the case when a disk having a mass imbalance amount A of 1
gcm is rotated at 100 Hz or more for example, the following is obtained from the expression (7):
8100.gtoreq.100.sup.2.times.(1-Z).
[0268] Eventually, the following is obtained:
Z.gtoreq.0.19.
[0269] In other words, by setting the balance amount Z due to the spherical bodies 24 at 0.19 gcm or more, the vibration amount of the sub-base 6 can be suppressed to the allowable value or less even if a CD-ROM disk having a mass imbalance amount A of 1 gcm is rotated at 100
Hz. For this reason, by setting the radius r [cm], the specific weight .rho. and the number of the spherical bodies 24, and the radius S [cm] of the inner wall face 25 of the outer periphery of the hollow ring-shaped portion 23 on the basis of the expression (6) so that the balance amount Z due to the spherical bodies 24 is 0.19 gcm or more, it is possible to attain a disk drive apparatus having a sufficient vibration suppression effect even if a disk having a mass imbalance amount A of 1 gcm is rotated at 100 Hz.
[0270] The descriptions in the above-mentioned embodiment have been provided with respect to a 12 cm diameter CD-ROM disk; however, even when any 12 cm diameter disk is used as a general recording medium, by setting the balance amount Z so that the maximum allowable value hc is 8100
gcm/sec.sup.2 or less, an excellent vibration suppression effect is obtained. Furthermore, even when a disk smaller than 12 cm in diameter is used, by setting the balance amount Z so that the maximum allowable value hc is 8100 gcm/sec.sup.2 or less, a vibration suppression effect is obtained as a matter of course.
[0271] Moreover, according to the expression (7), in the case when the rotation frequency of the disk 1 is raised to 120 Hz, the balance amount Z of the spherical bodies 24 becomes:
Z.gtoreq.0.43.
[0272] Therefore, the radius r [cm], the specific weight .rho. and the number of the spherical bodies 24, and the radius S [cm] of the inner wall face 25 of the outer periphery of the hollow ring-shaped portion 23
should only be set on the basis of the expression (6) so that the balance amount Z becomes 0.43 gcm or more.
[0273] Furthermore, a similar effect is obtained even when disks other than CD-ROM disks are used. For example, in the case of a disk having a maximum mass imbalance amount A of 2 gcm, a rotation frequency f0 is obtained wherein the magnitude of the vibration of the sub-base 6 is suppressed to the maximum allowable amount so that stable recording or reproduction can be attained while the rotation frequency of the disk is changed in a condition without mounting the spherical body balancer 22a. Then, the maximum allowable value h, f0.sup.2.times.A, is calculated, and the necessary balance amount Z due to the spherical bodies 24 at a target rotation frequency f (>f0) is obtained from the expression (7). In the end, by setting the radius r [cm], the specific weight .rho. and the number of the spherical bodies 24, and the radius S [cm] of the inner wall face 25 of the outer periphery of the hollow ring-shaped portion 23
so that the necessary balance amount Z can be obtained from the expression (6), it is possible to attain a disk drive apparatus capable of carrying out stable recording or reproduction even if a disk having a mass imbalance amount A of 2 gcm is rotated at the target rotation frequency f.
[0274] Furthermore, in the first embodiment of the present invention, the radius r [cm] and the number of the spherical bodies 24, and the radius S [cm] of the inner wall face 25 of the outer periphery of the hollow ring-shaped portion 23 are set to satisfy the following expression.
r/(S-r).ltoreq.sin{.pi./(2n)} (8).
[0275] This is used to optimize the number of the spherical bodies 24. By modifying the expression (8):
n.ltoreq..pi./2/sin n.sup.-1{r/(S-r)} (9).
[0276] This expression is obtained.
[0277] This means that the maximum value of the number n of the spherical bodies 24 is represented by the expression (9) in the case when the radius r [cm] of the spherical bodies 24 and the radius S [cm] of the inner wall face 25 of the outer periphery of the hollow ring-shaped portion 23 have been determined.
[0278] Furthermore, the magnitude of the balance amount Z due to the spherical bodies 24 can be obtained from the above-mentioned expression (6). From the expression (6), the maximum value Zmax of the balance amount Z is represented by:
Zmax={fraction (4/3)}.pi.r.sup.2.rho.(S-r).sup.2 (11),
[0279] at the time when
n sin.sup.-1{r/(S-r)}=.pi./2, that is,
n=.pi./2/sin.sup.-1{r/(S-r)} (10).
[0280] The expression (6) shows that the balance amount Z becomes smaller than Zmax represented by the expression (11) when the number n of the spherical bodies 24 is made larger than the value calculated by the expression (10). In other words, it is desirable that the number n of the spherical bodies 24 should be set at a value satisfying the expression (9). By this setting, it is possible to prevent the number n of the spherical bodies 24 from being set more than necessary in the case when the radius r [cm] of the spherical bodies 24 and the radius S [cm] of the inner wall face 25 of the outer periphery of the hollow ring-shaped portion 23 have been determined, whereby a necessary balance amount Z can be obtained by using an optimum number of pieces.
[0281] In the first embodiment, the primary resonance frequency in the direction parallel to the recording face of the disk 1 in the mechanical vibration of the sub-base 6 due to the deformation of the insulators 7 is set lower than the rotation frequency of the disk 1. This is done so that the direction of the vibration displacement due to the imbalance force F is set nearly opposite to the action direction of the imbalance force F.
[0282] Generally, in a mechanical vibration system comprising a spring and a mass, the phase of the frequency of an external force acting on the mass near its resonance frequency begins to dislocate from the phase of the frequency of the displacement due to the external force. In addition, at a frequency sufficiently higher than the resonance frequency, the dislocation between the phases becomes an electrical angle of about 180
degrees, whereby the action direction of the external force becomes opposite to the direction of the displacement. In other words, by setting the resonance frequency of the sub-base 6 at a frequency lower than the rotation frequency of the disk 1, wherein the direction of the vibration displacement due to the imbalance force F becomes nearly opposite to the action direction of the imbalance force F, the spherical bodies 24 gather at the positions nearly opposite to the center of gravity G1 of the disk 1 as described above. In addition, when the component of the centrifugal force q, acting on each of the spherical bodies 24 in the same direction of the imbalance force F, is a balance force zk, the action direction of the resultant force Zn of the balance forces zk becomes nearly opposite to the action direction of the imbalance force. Therefore, it is desirable that the resonance frequency of the sub-base 6 should be set in consideration of the direction of the vibration displacement due to the imbalance force F at the rotation frequency of the disk 1.
[0283] FIG. 3 shows the measured values of the vibration acceleration of the sub-base 6, and shows the results of an experiment for examining effects by the disk drive apparatus of the first embodiment using a disk 1 having a mass imbalance amount A of about 1 gcm. In this experiment, an ACCELEROMETER, MODEL 2250A-10 made by ENDEVCO (California, USA) was used as an acceleration sensor, and an ISOTRON AMPLIFIER, MODEL 102 made by ENDEVCO was used as an amplifier for the acceleration sensor.
[0284] In this experiment, the vibration acceleration of the sub-base 6
was measured when the disk 1 was rotated at about 100 Hz. (a) of FIG. 3
corresponds to the case of the conventional disk drive apparatus with no spherical body balancer. As shown in (a) of FIG. 3, vibration occurs at an acceleration of about 8 G at the maximum in the conventional disk drive apparatus. (b) of FIG. 3 corresponds to the case of the disk drive apparatus of the first embodiment of the present invention, and the vibration acceleration thereof is suppressed to about 3 G.
[0285] As described above, in the disk drive apparatus of the first embodiment, the vibration acceleration is suppressed drastically; therefore, the side pressure caused by the imbalance force F and applied to the bearings of the spindle motor 2 decreases, thereby solving the problems of increased loss of the shaft torque, damaged bearings and shorter service lives of the bearings.
[0286] As described above, thanks to the configuration of the disk drive apparatus of the first embodiment, the vibration of the sub-base 6 can be suppressed securely regardless of the mass imbalance amount A of the mounted disk 1 and the rotation frequency of the disk 1. Therefore, the disk drive apparatus of the first embodiment can carry out stable recording or reproduction even if a disk 1 having a large imbalance is rotated at high speed, whereby a disk drive apparatus capable of rotating at high speed can be attained.
Second Embodiment
[0287] Next, a disk drive apparatus in accordance with a second embodiment of the present invention will be described referring to the drawings. FIG. 4 is a side sectional view showing the vicinity of the spindle motor 2 of the disk drive apparatus in accordance with the second embodiment of the present invention. The elements substantially identical to those used for the disk drive apparatus of the first embodiment shown in the above-mentioned FIG. 1 are represented by the same numeral codes, and the descriptions for the preceding embodiment are applied, thereby omitting overlap descriptions.
[0288] The disk drive apparatus of the second embodiment of the present invention has a hollow ring-shaped portion 23, used as a ring-shaped track portion and having a ring-shaped passage accommodating spherical bodies 24 therein, just as in the case of the first embodiment. In the disk drive apparatus of the second embodiment, when the recording face of the disk 1 held on the turntable 110 is assumed to be a reference face, a spherical body balancer 22b provided rotatably and integrally with the rotor 80 is disposed on the same side of the head 3 with respect to this reference face.
[0289] As shown in FIG. 4, the radius of the outer wall face 102 of the outer periphery of the hollow ring-shaped portion 23 in the second embodiment is set smaller than the radius of the end face 103 of the inner peripheral side of the head 3 when the head 3 is positioned at the innermost track 117. The other configurations are the same as those of the above-mentioned first embodiment.
[0290] In the disk drive apparatus of the second embodiment configured as described above, the action of the spherical body balancer 22b is similar to that of the spherical body balancer 22a of the above-mentioned first embodiment, and the vibration of the sub-base 6 due to the mass imbalance of the disk 1 is suppressed securely by the above-mentioned configurations.
[0291] Furthermore, in the disk drive apparatus of the second embodiment of the present invention, when the recording face of the disk 1 held on the turntable 110 is assumed to be the reference face, the spherical body balancer 22b is disposed on the same side of the head 3 with respect to this reference face; therefore, the spherical body balancer 22b does not occupy any space above the disk 1, whereby the device can be made lower in profile.
[0292] Moreover, the radius of the outer wall face 102 of the outer periphery of the hollow ring-shaped portion 23 is set smaller than the radius of the end face 103 of the inner peripheral side of the head 3
when the head 3 is positioned at the innermost track 117, whereby the spherical body balancer 22b can be disposed in parallel with the head 3. Therefore, when the recording face of the disk 1 is assumed to be the reference face, the spherical body balancer 22b does not occupy any new space even in the space on the same side of the head 3 with respect to this reference face, whereby the device can be made lower in profile even if the spherical body balancer 22b is mounted.
[0293] In the disk drive apparatus of the second embodiment of the present invention, the radius S of the inner wall face 25 of the outer periphery of the hollow ring-shaped portion 23 is required to be made smaller; however, a sufficient vibration suppression effect can be obtained by setting the radius r [cm], the specific weight .rho. and the number of the spherical bodies 24, and the radius S [cm] of the inner wall face 25
of the outer periphery of the hollow ring-shaped portion 23 so as to satisfy the above-mentioned expressions (6), (7) and (8), just as in the case of the above-mentioned first embodiment. For example, in the case of a CD-ROM disk, the radius of its innermost track 117 is 2.3 cm, and the mass imbalance amount A of a 12 cm diameter CD-ROM disk is about 1 gcm at the maximum. As described above, in the conventional disk drive apparatus, when a disk having a mass imbalance amount A of 1 gcm is rotated, the limit rotation frequency thereof is about 90 Hz. Therefore, in the case of a CD-ROM disk drive apparatus, the maximum allowable value hc represented by f.sup.2.times.A becomes:
hc=90.sup.2.times.1=8100 gcm/sec.sup.2.
[0294] In the case when a disk having a mass imbalance amount A of 1 gcm is rotated at 120 Hz or more for example even in the disk drive apparatus of the second embodiment of the present invention, the following is obtained from the expression (7):
8100.gtoreq.120.sup.2.times.(1-Z).
[0295] Eventually, the following is obtained:
Z.gtoreq.0.43.
[0296] In other words, by setting the balance amount Z due to the spherical bodies 24 at 0.43 gcm or more, the vibration amount of the sub-base 6 can be suppressed to the allowable value or less even if a CD-ROM disk having a mass imbalance amount A of 1 gcm is rotated at 120
Hz.
[0297] The distance from the center of the lens 104 of the head for reproduction on a CD-ROM disk to the end face 103 of the inner peripheral side of the head 3 is generally about 0.7 cm, and the clearance between the end face 103 of the inner peripheral side of the head 3 and the outer wall face 102 of the outer periphery of the hollow ring-shaped portion 23
is 0.1 cm. Furthermore, in the case when the outer peripheral wall of the hollow ring-shaped portion 23 is formed of a resin material, and when its thickness is set at 0.1 cm, the radius S [cm] the inner wall face 25 of the outer periphery of the hollow ring-shaped portion 23 is represented by:
S=2.3-0.7-0.1-0.1=1.4 cm.
[0298] When the head 3 is positioned at the innermost track 117, the distance from the center of the lens 104 of the head 3 to the center of the shaft of the spindle motor 2 is 2.3 cm.
[0299] In the second embodiment, when the spherical body 24 is formed of a steel ball having a specific weight .rho. of about 7.8 and a radius r [cm] of 0.1 cm, the maximum number n of the spherical bodies 24 is obtained from the expression (9), a modified expression of the above-mentioned expression (8), as follows:
n.ltoreq.20 pieces,
[0300] from n.ltoreq..pi./2/sin.sup.-1{0.1/(1.4-0.1)]. In the case when the maximum number of the spherical bodies 24 is 20, and when the radius r=0.1 cm, the specific weight .rho.=7.8, n=13 and S=1.4 cm are substituted in the expression (6):
Z=0.55 gcm,
[0301] is obtained, and when the number n of the spherical bodies 24 is set the maximum value of 20, the balance amount Z due to the spherical bodies 24 satisfies the necessary value of 0.43 gcm or more.
[0302] Furthermore, a balance amount in the case when the number of the spherical bodies 24 is decreased is obtained by using the expression (6); when the number n is decreased to 12, the balance amount Z becomes 0.44
gcm. Therefore, by using the spherical bodies 24 formed of steel balls having a radius r [cm] of 0.1 cm and by setting the number n of the spherical bodies 24 in the range of 12 to 20, it is possible to attain a low-profile disk drive apparatus having a sufficient vibration suppression effect even if a disk having a mass imbalance amount A of 1
gcm is rotated at 120 Hz.
[0303] As described above, thanks to the configuration of the disk drive apparatus of the second embodiment, the vibration of the sub-base 6 can be suppressed securely without making the device thicker even in the case when the mass imbalance amount A of the mounted disk 1 is large. Therefore, the disk drive apparatus of the second embodiment can carry out stable recording or reproduction even if a disk 1 having a large mass imbalance is rotated at high speed, whereby it is possible to attain a disk drive apparatus being low in profile and capable of rotating at high speed.
Third Embodiment
[0304] Next, a disk drive apparatus in accordance with a third embodiment of the present invention will be described referring to the drawings. FIG. 5 is a side sectional view showing the vicinity of the spindle motor 2 of the disk drive apparatus in accordance with the third embodiment of the present invention. The elements substantially identical to those used for the disk drive apparatuses of the above-mentioned first and second embodiments are represented by the same numeral codes, and the descriptions for the preceding embodiments are applied, thereby omitting overlap descriptions.
[0305] In the disk drive apparatus of the third embodiment of the present invention, as shown in FIG. 5, just as in the case of the above-mentioned first embodiment, a spherical body balancer 22a is formed so as to be rotatable integrally with the rotor 80 of the spindle motor 2. The spherical body balancer 22a comprises a hollow ring-shaped portion 23
used as a ring-shaped track portion having a ring-shaped passage provided coaxially with the spindle shaft 21 of the spindle motor 2, and a plurality of spherical bodies 24 movably accommodated inside the passage of the hollow ring-shaped portion 23.
[0306] Furthermore, referring to FIG. 5, in the disk drive apparatus of the third embodiment, the disk 1 on the turntable 110 is pressed and secured by the positioning ball 116, thereby being configured so as to be rotated by the spindle motor 2. In this disk drive apparatus, a head (not shown) is used to read data recorded on the disk 1 or to write data on the disk 1. A motor base 9 to which the spindle motor 2 is secured is mounted on the sub-base 6 via elastic bodies 40. In addition, the head drive motor, the head drive mechanism and the like are mounted on the sub-base 6.
[0307] As shown in FIG. 5, the sub-base 6 is mounted on the main base 8
via the insulators 7, and vibration and impact transmitted from outside the device to the sub-base 6 are dampened by the insulators 7. The main unit of the disk drive apparatus shown in FIG. 5 is configured so as to be built in a computer or the like via a frame (not shown) installed on the main base 8.
[0308] The disk drive apparatus of the third embodiment uses the elastic bodies 40 having low rigidity to connect the motor base 9 to the sub-base 6. In the disk drive apparatus of the third embodiment, the primary resonance frequency of the mechanical vibration of the motor base 9 due to the deformation of the elastic bodies 40, in the direction parallel to the recording face of the disk 1, is set lower than the rotation frequency of the disk 1. More specifically, the rotation frequency of the disk 1 is about 100 Hz. In addition, both the primary resonance frequency of the vibration of the motor base 9 in the direction (tracking direction) wherein the head is driven by the head drive mechanism and the primary resonance frequency of the vibration of the motor base 9 in the direction perpendicular thereto are set at about 60 Hz.
[0309] In the disk drive apparatus of the third embodiment of the present invention configured as described above, operation in the case when the disk 1 having a large mass imbalance amount A is rotated at 100 Hz will be described referring to the above-mentioned FIGS. 2 and 5.
[0310] First, a centrifugal force F (referred to as an imbalance force) acts on the disk 1 at the center of gravity G1 thereof, and the direction of the action rotates as the disk 1 rotates. By the imbalance force F, the elastic bodies 40 are deformed, and the motor base 9 as well as the spindle motor 2, the spherical body balancer 22a and the disk 1 mounted on the motor base 9 whirl at the rotation frequency of the disk 1. In the disk drive apparatus of the third embodiment, the resonance frequency (about 60 Hz) of the motor base 9 due to the deformation of the elastic bodies 40 is set lower than the rotation frequency (about 100 Hz) of the disk 1. Therefore, the displacement direction of the motor base 9 and the action direction of the imbalance force F are nearly opposite to each other at all times. In other words, the motor base 9 whirls in a phase nearly opposite to that of the imbalance force F. Therefore, just as in the case of the above-mentioned first embodiment shown in FIG. 2, the whirling center axis P1 of the disk 1 rotating on the motor base 9 is disposed between the center of gravity G1 of the disk 1 on which the imbalance force F acts and the rotation center axis P0 of the spindle motor.
[0311] In the above-mentioned condition, since the hollow ring-shaped portion 23 integrally provided with the rotor 80 is positioned so as to be coaxial with the rotation center axis P0 of the spindle motor 2, the center of the hollow ring-shaped portion 23, i.e., the center P2 of the inner wall face 25 of the outer periphery thereof, coincides with the position of the rotation center axis P0 of the spindle motor 2. Therefore, the hollow ring-shaped portion 23 carries out whirling operation around the whirling center axis P1.
[0312] At this time, a centrifugal force q acts on the spherical body 24
accommodated in the hollow ring-shaped portion 23 in the direction of connecting the whirling center axis P1 to the center of gravity of the spherical body 24. In addition, the movement of the spherical body 24 is restricted by the inner wall face 25 of the outer periphery of the hollow ring-shaped portion 23. Therefore, a reaction N from the inner wall face 25 of the outer periphery acts on the spherical body 24. This reaction N from the inner wall face 25 of the outer periphery acts toward the center P2 of the inner wall face 25 of the outer periphery. Therefore, a movement force R, i.e., the resultant force of the centrifugal force q and the reaction N, acts on the spherical body 24 in the direction of the tangent of the circle centered at the center P2 of the inner wall face 25
of the outer periphery, passing through the center of gravity of the spherical body 24, and being away from the whirling center axis P1. By this movement force R, the spherical body 24 is moved along the inner wall face 25 of the outer periphery, whereby the spherical bodies 24
gather in the direction nearly opposite to the center of gravity G1 of the disk 1 with respect to the whirling center axis P1.
[0313] As a result, when the component of the centrifugal force q, acting on each of the spherical bodies 24 having gathered in the same direction of the imbalance force F, is a balance force zk, the imbalance force F due to the rotation of the disk 1 is canceled by the resultant force Zn of the balance forces zk, whereby the force acting on the motor base 9
decreases. Therefore, even if the unbalanced disk 1 is rotated, the vibration of the motor base 9 is suppressed, whereby the vibration of the disk 1 mounted on the motor base 9 is also suppressed. In addition, the vibration transmitted to the sub-base 6 connected to the motor base 9 via the elastic bodies 40 is reduced, and the vibration of the head 3 mounted on the sub-base 6 is also suppressed.
[0314] In the above-mentioned first embodiment, by setting the resonance frequency (about 60 Hz) of the sub-base 6 due to the deformation of the insulators 7 lower than the rotation frequency (about 100 Hz) of the disk 1, it is attained that the hollow ring-shaped portion 23 whirls in a phase nearly opposite to that of the imbalance force F. On the other hand, in the disk drive apparatus of the third embodiment of the present invention, by mounting the motor base 9 over the sub-base 6 via the elastic bodies 40 and by setting the resonance frequency (about 60 Hz) of the motor base 9 due to the deformation of the elastic bodies 40 lower than the rotation frequency (about 100 Hz) of the disk 1, it is attained that the hollow ring-shaped portion 23 whirls in a phase nearly opposite to that of the imbalance force F. With this configuration, just as in the case of the above-mentioned first embodiment, the spherical bodies 24
securely gather toward the position nearly opposite to the center of gravity G1 of the disk 1, whereby the mass imbalance of the disk 1 is securely canceled by the spherical bodies 24.
[0315] In order to raise the vibration suppression effect of the spherical body balancer of the present invention, it is desirable that the spherical bodies 24 gather accurately at position nearly opposite to the center of gravity G1 of the disk 1, that the action direction of the whirling of the hollow ring-shaped portion 23 and the action direction of the imbalance force F are nearly opposite to each other in phase as much as possible, and that the locus of the whirling of the center of the hollow ring-shaped portion 23 forms a condition of a nearly perfect circle. Therefore, in the third embodiment of the present invention, the elastic bodies 40 are newly provided to attain this optimum vibration condition. In addition, the third embodiment can easily attain a condition more optimal than the above-mentioned first embodiment wherein the insulators 7 are used both in attaining the above-mentioned vibration condition and in dampening the vibration and impact transmitted from outside the device to the sub-base 6. For example, by setting the shape of the motor base 9 so that the center of gravity of the whole of the motor base 9 and the spindle motor 2 mounted on the motor base 9 is disposed at the rotation center axis P0 of the spindle motor 2, and by disposing three or four elastic bodies 40 at equiangular pitches on the same radius from the rotation center axis P0, both the center of gravity of the whole of the components mounted on the whirling motor base 9 and the support center of the elastic bodies 40 can be positioned on the rotation center axis P0 of the spindle motor 2. Therefore, in accordance with the third embodiment, the locus of the whirling of the center of the hollow ring-shaped portion 23 can form a nearly perfect circle.
[0316] Furthermore, in the disk drive apparatus of the third embodiment, the rigidity of the elastic body 40 can be set easily at a desirable magnitude so that the whirling of the hollow ring-shaped portion 23 and the action direction of the imbalance force F are nearly opposite to each other in phase; and it is possible to carry out setting so that only the whirling vibration mode occurs by optimizing the rigidity of the elastic bodies 40 in the direction of the rotation center axis P0 and in the direction perpendicular thereto.
[0317] As described above, thanks to the configuration of the disk drive apparatus of the third embodiment, it is possible to easily attain the optimum vibration condition for further raising the vibration suppression effect of the spherical body balancer 22a; and even when the mass imbalance amount of the mounted disk 1 is large, the vibration of the motor base 9 and the sub-base 6 can be suppressed securely. Therefore, the disk drive apparatus of the third embodiment can carry out stable recording or reproduction even if a disk 1 having a large mass imbalance is rotated at high speed, whereby a disk drive apparatus capable of rotating at high speed can be attained.
Fourth Embodiment
[0318] Next, a disk drive apparatus in accordance with a fourth embodiment of the present invention will be described referring to the drawings. FIG. 6 is a plan sectional view showing a spherical body balancer 22c provided integrally with the rotor 80 in the disk drive apparatus of the fourth embodiment of the present invention. The elements substantially identical to those used for the disk drive apparatus of the above-mentioned first embodiment are represented by the same numeral codes, and the descriptions for the preceding embodiment are applied, thereby omitting overlap descriptions.
[0319] In the disk drive apparatus of the fourth embodiment of the present invention, as shown in FIG. 6, just as in the case of the above-mentioned first embodiment, the spherical body balancer 22c is formed so as to be rotatable integrally with the rotor 80 of the spindle motor 2. This spherical body balancer 22c comprises a hollow ring-shaped portion 23c used as a ring-shaped track portion provided coaxially with the spindle shaft 21 of the spindle motor 2, and a plurality of spherical bodies 24
movably accommodated inside this hollow ring-shaped portion 23c.
[0320] Furthermore, in the disk drive apparatus of the fourth embodiment of the present invention, the inner wall face 25c of the outer periphery of the hollow ring-shaped portion 23c of the spherical body balancer 22c is inclined with respect to the center axis (P2 of FIG. 6) of the hollow ring-shaped portion 23c. Except for the above, the configuration is the same as that of the above-mentioned first embodiment.
[0321] In the disk drive apparatus of the fourth embodiment configured as described above, in the case when the disk 1 having a large mass imbalance amount A is rotated, the hollow ring-shaped portion 23c performs whirling operation around the whirling center axis P1, just as in the case of the above-mentioned first embodiment shown in FIG. 2.
[0322] At this time, a centrifugal force q acts on the spherical body 24
accommodated in the hollow ring-shaped portion 23c in the direction of connecting the whirling center axis P1 to the center of gravity of the spherical body 24. In addition, since the movement of the spherical body 24 is restricted by the inner wall face 25c of the outer periphery of the hollow ring-shaped portion 23, a reaction N from the inner wall face 25c of the outer periphery acts on the spherical body 24. As shown in FIG. 6, this reaction N from the inner wall face 25c of the outer periphery acts perpendicular to the inner wall face 25c of the outer periphery; therefore, it has a component N1 in the direction toward the center P2 of the hollow ring-shaped portion 23c and a component N2 in the direction parallel with the center axis P2 of the hollow ring-shaped portion 23c. Therefore, as shown in FIG. 2, a movement force R, i.e., the resultant force of the centrifugal force q and the component N1 of the reaction N, acts on the spherical body 24 in the direction of the tangent of the circle centered at the center P2 of the inner wall face 25c of the outer periphery, passing through the center of gravity of the spherical body 24, and being away from the whirling center axis P1. By this movement force R, the spherical body 24 is moved along the inner wall face 25c of the outer periphery, whereby the spherical bodies 24 gather in the direction nearly opposite to the center of gravity G1 of the disk 1 with respect to the whirling center axis P1.
[0323] As a result, when the component of the centrifugal force q, acting on each of the spherical bodies 24 having gathered in the same direction of the imbalance force, is a balance force zk, the imbalance force F due to the rotation of the disk 1 is canceled by the resultant force Zn of the balance forces zk, whereby the force acting on the sub-base 6
decreases. Therefore, the vibration of the sub-base 6, occurring in the case when an unbalanced disk 1 is rotated, is suppressed.
[0324] Furthermore, the spherical body 24 is pressed against the bottom face of the hollow ring-shaped portion 23c by the component N2 of the reaction N. Therefore, even if vibration and impact are applied from outside the device in the direction of the center axis P2 of the hollow ring-shaped portion 23c, the spherical body 24 remains the condition of making contact with the bottom face of the hollow ring-shaped portion 23c by virtue of the component N2 of the reaction N. For this reason, in the fourth embodiment, the spherical body 24 does not freely move in the direction parallel with the center axis P2 of the hollow ring-shaped portion 23c inside the hollow ring-shaped portion 23c, whereby it is possible to avoid the problem of generating noise due to collisions of the spherical bodies 24 with the ceiling face and the bottom face of the hollow ring-shaped portion 23c.
[0325] As described above, in the configuration of the fourth embodiment of the present invention, thanks to the spherical body balancer 22c, it is possible to suppress the vibration of the sub-base 6, and it is possible to prevent undesirable noise from occurring from the spherical body balancer 22c itself.
Fifth Embodiment
[0326] Next, a disk drive apparatus in accordance with a fifth embodiment of the present invention will be described referring to the drawings. FIG. 7 is a plan sectional view showing a spherical body balancer 22d having a hollow ring-shaped portion 23d and provided integrally with the rotor 80 in the disk drive apparatus of the fifth embodiment of the present invention. The elements substantially identical to those used for the disk drive apparatus of the above-mentioned first embodiment are represented by the same numeral codes, and the descriptions for the preceding embodiment are applied, thereby omitting overlap descriptions.
[0327] The disk drive apparatus of the fifth embodiment of the present invention, just as in the case of the above-mentioned fourth embodiment, is intended to decrease the level of noise occurring from the balancer itself. As shown in FIG. 7, the spherical body balancer 22d is formed so as to be rotatable integrally with the rotor 80 of the spindle motor 2. This spherical body balancer 22d comprises a hollow ring-shaped portion 23d used as a ring-shaped track portion provided coaxially with the spindle shaft 21 of the spindle motor 2, and a plurality of spherical bodies 24 movably accommodated inside the hollow ring-shaped portion 23d.
[0328] As shown in FIG. 7, the cross-section of the inner wall of the outer periphery of the spherical body balancer 22d is formed in a wedge shape. Except for the above, the configuration is the same as that of the above-mentioned first embodiment.
[0329] In the disk drive apparatus of the fifth embodiment configured as described above, in the case when the disk 1 having a large mass imbalance amount A is rotated, the hollow ring-shaped portion 23d performs whirling operation around the whirling center axis P1, just as in the case of the above-mentioned first em