JP3763765B2 - Disk unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a disk device such as a DVD, CD, DVD-ROM, CD-ROM, MO and MD.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, disk devices that record / reproduce video signals, audio signals, and data signals with respect to a disk are known. The disk device includes a spindle motor that rotates the disk at a predetermined rotational speed with high accuracy, and a clamper that fixes the disk to the spindle motor so that the disk and the spindle motor rotate together. Also, a pickup for recording / reproducing various signals is provided, and the pickup is arranged to face the disk surface and moves (seek) from the inner circumference side to the outer circumference side or from the outer circumference side to the inner circumference side in the disk radial direction. It moves randomly in the disk radial direction (track jump) and records / reproduces various signals.
[0003]
Next, a method for rotating the spindle motor when various signals are recorded / reproduced by the pickup will be described.
Now, it is assumed that the disk is rotated at a constant rotational speed by the spindle motor (the angular velocity is constant). At this time, the velocity vector (linear velocity) of the disc with respect to the pickup in the disc tangential direction varies depending on the position of the pickup in the disc radial direction, and increases as the pickup moves from the inner circumference side to the outer circumference side. The linear velocity increase rate is proportional to the amount of movement of the pickup that moves in the disk radial direction. Such disk rotation is called CAV (Constant Angular Velocity). It is also possible to make the linear velocity constant by controlling the number of revolutions of the spindle motor as the pickup moves in the radial direction of the disc, and such disc rotation is called CLV (Constant Linear Velocity).
[0004]
DVDs, CDs, DVD-ROMs, CD-ROMs, MDs, and the like are generally reproduced by CLV. For example, when connected to a personal computer (hereinafter abbreviated as a personal computer), they are recorded on a disc. The CAV is used because a high response (response time) is required to reproduce the transmitted data signal as soon as possible and transmit it to the personal computer. Therefore, when a signal recorded in CLV is reproduced, the frequency band of the reproduced signal becomes wider as the movement amount of the pickup increases. In N-times speed playback, CAV is generally used.
[0005]
In the case of CLV, the rotational speed of the spindle motor must be changed depending on the radial position of the pickup with respect to the disk. For example, when reproducing the innermost signal and then reproducing the outermost signal, 1 × speed, about 1400 rpm to about 500 rpm = about 900 rpm deceleration, DVD N × speed about 900 rpm × N, CD 1 × speed about 500 rpm−about 200 rpm = about 300 rpm deceleration, CD N × speed Then, a deceleration of about 300 rpm × N is required. The torque of the spindle motor required for deceleration is proportional to the inertia of the rotating body (spindle motor, disk, etc.) and the required amount of change in the rotational speed, and inversely proportional to the required response. For this reason, in order to obtain a high response in CLV N-times speed reproduction, a low inertia spindle motor that generates a large torque is required. In addition, the inertia of the disc depends on the mechanical dimensions determined by the standard, but there is a poor product that does not satisfy the standard. Therefore, it is difficult to obtain a high response with CLV.
[0006]
On the other hand, N-times speed reproduction has been performed, and the eccentric center of gravity of the disk has become a problem. This is because as the rotational speed of the spindle motor increases, the excitation force due to the eccentric center of gravity of the disk increases and causes vibrations in the disk device. This vibration causes device noise, reproduction signal deterioration, and spindle motor life reduction.
[0007]
As a countermeasure against the above vibration, a disk device equipped with an autobalancer is known. The basic structure of the autobalancer-equipped disk device will be described with reference to FIG. The autobalancer-equipped disk device 200 includes a spindle motor 210, a turntable 220 with an autobalancer fixed to a rotating shaft 211 of the spindle motor 210, and a clamper 230. A magnet 222 is fixed to the upper portion of the turntable body 221, and the clamper 230 is attracted to the magnet 222, so that the disk 240 rotates integrally with the spindle motor shaft 211 and the turntable body 221. It is clamped by the clamper 230. A balancer holder 223 is provided at the lower part of the turntable body 221, and a balancer holder groove 223 a is formed in an annular shape around the rotation shaft 211 of the spindle motor 210. A plurality of balancer balls 224 are movably disposed in the balancer holder groove 223a. The opening of the balancer holder groove 223a is closed by the turntable body 221.
[0008]
The autobalancer-equipped disk device 200 configured as described above is fixed to a mechanical chassis 300 of the disk device body as shown in FIG. The mechanical chassis 300 is attached to the mechanical base 400 with four mounting screws 320 via four insulators 310 (blocking disturbance vibrations). As a result, the disk device main body constitutes a vibration system with the insulator 310 serving as a spring element and vibration damping element and the mechanical chassis 300 supported by the insulator 310 serving as a mass element. The vibration system is divided into a vibration system (longitudinal vibration) in the rotation axis direction (Z direction) of the rotating spindle motor and a vibration system (lateral vibration) in the disk radial direction. When a disk having an eccentric gravity center is rotated at a predetermined rotational speed, the spindle motor acts as a source for generating an excitation force for the vibration system. The effect of the autobalancer can be obtained by designing the transverse vibration resonance rotational speed ω0 (rad / s) of the vibration system to be sufficiently smaller than the CAV rotational speed ω of the spindle motor.
[0009]
Next, the operation of the autobalancer will be described with reference to FIGS.
The mechanical chassis 300 and the insulator 310 constitute a transverse vibration system having a resonance rotational speed ω0. FIG. 11A schematically shows the spring element of the insulator 310 by four springs. Consider a case where a disk 340 having an eccentric gravity center is fixed to the autobalancer-equipped disk device 200 and the rotational speed ω is gradually increased. The eccentric center of gravity is represented by a model in which the rotational imbalance amount m is attached to a position on the disk 340 that is separated from the center of the disk 340 by a distance e. Furthermore, in order to make the drawing easier to see, the center of gravity G of the mechanical chassis 300 and the rotation locus virtual center C0 of G are illustrated far apart from the rotation center C of the disk device 200 with the autobalancer. In general, the actual G and C are designed to be as close as possible.
[0010]
FIG. 11A shows a state where the rotation of the autobalancer-equipped disk device 200 is ω << ω0. At this time, the balancer ball 224 of the autobalancer-equipped disk device 200 exists at an arbitrary position, but as the lateral vibration of the mechanical chassis 300 caused by the excitation force generated by the eccentric gravity center of the disk increases. Get together. That is, the locus of the center of gravity position G of the mechanical chassis 300 rotates around the rotation center C0 of the lateral vibration caused by the excitation force at a rotation speed of Ω (= ω). The centrifugal force generated at this time also acts on the autobalancer-equipped disk device 200, and the balancer balls 224 gather in the direction in which G exists as viewed from C0. Further, the position of the rotational imbalance amount m viewed from the rotation center C of the disk device 200 equipped with the autobalancer and the position of the center of gravity G viewed from the virtual center C0 of the mechanical chassis 300 (the phase difference between ω and Ω) Always leading, Ω is the same value as ω, but only the phase is gradually delayed.
[0011]
FIG. 11B shows a state in which the rotation of the autobalancer-equipped disk device 200 is ω = ω0. At this time, the position of the rotational imbalance amount m viewed from the rotation center C of the autobalancer-equipped disk device 200 and the position of the center of gravity G viewed from the virtual center C0 of the mechanical chassis 300 (phase difference between ω and Ω) are approximately The relationship is 90 ° phase shift, and the mechanical chassis 300 vibrates most intensely because of a resonance state of a lateral vibration system. The balancer balls 224 are gathered by centrifugal force generated by the mechanical chassis 300 in the direction of the center of gravity G viewed from the virtual center C0 of the mechanical chassis 300. However, as the rotational speed ω of the autobalancer-equipped disk device 200 increases beyond the resonant rotational speed ω0, the vibration of the mechanical chassis 300 converges so as to satisfy the following expression.
XM / em = 1
(X: mechanical chassis vibration, M: mechanical chassis + disk mass, m: rotational unbalance amount, e: unbalance position)
If there is no autobalancer, the mechanical chassis 300 continues to vibrate with the residual displacement amount Xr = em / M obtained from the above equation, but if there is an autobalancer, the centrifugal force generated at this time Acts on the balancer ball 224, the balancer ball 224 moves according to the unbalance amount m and automatically converges the vibration.
[0012]
FIG. 11C shows a state in which the rotation of the autobalancer-equipped disk device 200 is ω >> ω0. According to the calculation, the XM / em ratio, which shows the maximum value at ω = ω0, decreases to about 1.3 without auto balancer when ω exceeds twice ω0, and the phase difference becomes about 135 degrees or more. Thereafter, the XM / em ratio approaches 1 and the phase difference asymptotically approaches 180 degrees. The autobalancer further reduces the residual vibration Xr and brings the XM / em ratio closer to zero. Further, since the effect of the autobalancer increases as the phase difference exceeds 90 degrees and approaches 180 degrees, it is necessary to rotate at ω exceeding twice ω0.
[0013]
However, in the above-described autobalancer-equipped disk device 200, the vibration system constituted by the mechanical chassis 300 and the insulator 310 is particularly used until the rotational speed of the spindle motor 210 is increased to ω> 2 × ω0 where the autobalancer functions. When the resonance speed is exceeded, the balancer balls collide with each other to generate a large impact sound (in order to cancel a large disc eccentric center of gravity, the impact sound increases as the mass of the balancer ball increases). is there.
[0014]
Therefore, in Japanese Patent Application Laid-Open No. 2000-48474 (conventional example 1) shown in FIG. 12, a plurality of balancer balls 524 and the same number of springs 525 are alternately inserted into an annular groove 523a formed in the balancer holder 523. Disclosure According to this, the collision sound between balancer balls can be prevented.
[0015]
13 (conventional example 2) shown in FIG. 13, the width of the annular groove 623a formed in the balancer holder 623 is large in the radial direction, and the bottom surface of the annular groove 623a is the rotation of the spindle motor 610. It is disclosed that it is inclined toward the center, and pockets 623b in which one balancer ball 624 can be stored are formed on the rotation center side of the inclination. According to this, when the rotational speed of the spindle motor 610 is low, that is, when the centrifugal force generated by the spindle motor 610 is small and the balancer ball 624 cannot run up the slope of the annular groove 623a, the collision of the balancer ball 624 occurs. There is no sound.
[0016]
[Problems to be solved by the invention]
However, in the former (conventional example 1), the spring 525 slides with the balancer holder 523 to generate a large frictional force, which prevents the balancer ball 524 from moving smoothly, and the spring 525 causes the balancer ball 524 to move to the balancer holder. There is a problem in that longitudinal vibration is caused in the circumferential direction by the annular groove 523a of 523, and this becomes disturbance vibration accompanying rotation of the spindle motor 510, thereby reducing the reliability of the apparatus.
[0017]
In the latter case (conventional example 2), the centrifugal force is gradually increased by the rotation of the spindle motor 610, and the balancer ball 624 jumps out of the pocket 623b and runs up the slope when the rotation speed reaches a predetermined rotational speed. Under a situation where acceleration / deceleration is not smoothly performed, there is a problem that the balancer balls 624 collide with each other to generate a collision sound.
[0018]
Further, as a means for solving the above-mentioned problems, a liquid is injected into an annular groove in which a balancer ball of a balancer holder is movably arranged, and the liquid is used as a balancer while the collision sound between the balancer balls is generated. It may be possible to reduce the friction of the spring, but it is necessary to add packing parts to prevent liquid leakage, and the assembly work becomes difficult, which increases costs and increases the reliability of the device due to liquid leakage. There is a problem that it leads to a decrease in performance.
[0019]
The present invention has been made in view of such a situation, and an object of the present invention is to provide a highly reliable disk device that prevents a collision sound between balancer balls of an autobalancer.
[0020]
[Means for Solving the Problems]
In order to solve the above-described problems, the disk device according to the present invention employs the following means.
[0021]
A first gist of the present invention is a spindle motor, a turntable fixed to a rotating shaft of the spindle motor, on which a disk is placed, and the disk is sandwiched between the turntable and integrated with the disk. And a clamper that rotates around the rotation axis of the spindle motor. Balance holder A plurality of balancer balls movably disposed in the annular groove, and a balancer plate disposed between the balancer balls. Said The present invention relates to a disk device characterized in that it is lightly fitted so as to be rotatable about the axis of a balance holder, and each balancer plate has a function as an autobalancer together with each balancer ball.
[0022]
According to the first aspect of the present invention, when the disc and the clamper are rotated together by the spindle motor, a plurality of balancer balls are gathered in a part of the annular groove when the disc has an eccentric center of gravity. Will be cancelled. At this time, collision between the balancer balls is avoided by the balancer plate disposed between the balancer balls.
[0023]
The second gist of the present invention is that the spindle motor, the turntable fixed to the rotation shaft of the spindle motor and on which the disk is placed, and the disk is sandwiched between the turntable and rotate integrally with the disk. In a disk device including a clamper, the turntable is formed around a rotation axis of the spindle motor. Balance holder A plurality of balancer balls movably disposed in the annular groove, and a balancer plate disposed between the balancer balls. Said The present invention relates to a disk device characterized in that it is lightly fitted so as to be rotatable about the axis of a balance holder, and each balancer plate has a function as an autobalancer together with each balancer ball.
[0024]
According to the second aspect of the present invention, when the disc and the turntable are rotated together by the spindle motor, a plurality of balancer balls are gathered in a part of the annular groove when the disc has an eccentric gravity center. The mind is cancelled. At this time, collision between the balancer balls is avoided by the balancer plate disposed between the balancer balls.
[0025]
According to a third aspect of the present invention, there is provided the disk device according to the first or second aspect, wherein the balancer plate is formed from a resin material at least a portion where the balancer ball abuts.
[0026]
According to the third aspect of the present invention, the balancer balls come into contact with the portion molded from the resin material, and collision between the balancer balls is avoided.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a disk device according to the present invention will be described below with reference to the drawings.
1 to 4 illustrate an embodiment (1) of a disk device according to the present invention.
FIG. 1 is a side sectional view showing a disk device 100 according to the present invention. The disk device 100 is schematically composed of a spindle motor 10, a turntable 20 and a clamper 30, and a disk 40 is sandwiched between the turntable 20 and the clamper 30.
[0028]
The spindle motor 10 rotates the disk 40 at a predetermined number of revolutions, and a brushless motor or a DC motor such as a brush motor is generally used. The spindle motor 10 is provided with a rotating shaft 11 protruding from one end face 12.
[0029]
As shown in FIG. 2, the turntable 20 includes a turntable main body 21, a ring sheet 22, a spring 23, an alignment ring 24, and a cap 25. The turntable main body 21 is formed in a substantially disc shape, and a through hole 21 a is formed in the center portion to be fitted and fixed to the rotary shaft 11 of the spindle motor 10. The ring sheet 22 is for preventing slippage between the turntable 20 and the disk when the turntable 20 is rotated by the spindle motor 10, and is attached to the upper surface 21 b of the turntable body 21. The alignment ring 24 is formed in a substantially disc shape having an inclined surface 24a on the outer peripheral portion, and by placing the disc 40, the edge portion 40b of the inner peripheral hole 40a of the disc 40 comes into contact with the inclined surface 24a so that the disc 40 is Center. The spring 23 is, for example, a coil spring formed in a substantially conical cross-sectional shape, and is arranged between the turntable 21 and the alignment ring 24 so that the central axis coincides with the rotation axis 11. Is urged upward by its elastic force. The cap 25 is lightly fitted with a through-hole 24b formed in the center of the alignment ring 24, and a cylindrical portion 25a that guides the alignment ring 24 so as to be movable in the vertical direction. It is comprised from the collar part 25b which restrict | limits the movement amount. The cap 25 is formed of a metal material so as to be attracted by a magnet provided in the clamper 30 described later. The cap 25 is fitted and fixed to the rotary shaft 11 of the spindle motor 10 through a through hole 25c formed at the center.
[0030]
As shown in FIG. 3, the clamper 30 includes a clamper body 31, a magnet 32, a balancer holder 33, a balancer ball 34, a balancer plate 35, and an upper lid 36. The clamper main body 31 is formed in a substantially disc shape having a hole 31 a in the center, and is disposed above the turntable 20. A stepped portion 31b whose inside is lowered is formed around the hole 31a of the clamper main body 31, and a magnet 32 formed in a disk shape having a hole 31a at the center is fixed to the stepped portion 31b. The balancer holder 33 is formed in a substantially disk shape and is disposed on the upper portion of the clamper body 31. The balancer holder 33 protrudes upward to form a shaft 33c, and a magnet having a hole 33a for fitting with the rotating shaft 11 of the spindle motor 10 at the bottom. A cylindrical portion 33e that fits into the 32 holes 32a is formed to protrude downward. The balancer ball 34 is movably disposed in an annular groove 33 b formed in the balancer holder 33. As the balancer ball 34, a metal material having a large mass is used. The balancer plate 35 is formed in a substantially elongated plate shape having a hole 35e at one end and an overhanging portion 35f at the other end, and the hole 35e is lightly fitted to the shaft 33c of the balancer holder 33 so as to be freely rotatable (note that The overhanging portion 35f is formed wider than the central portion 35g of the balancer plate 35 and increases the inertia of the balancer plate 35 around the shaft 33c). Further, the balancer plate 35 is composed of, for example, three balancer plates 35a, 35b, and 35c, and each balancer plate 35 is disposed between a plurality of balancer balls 34 as shown in FIG. The balancer plate 35 may be formed from a material that does not generate a collision sound due to the collision between the balancer balls. For example, a resin material or a metal material having vibration damping characteristics is applied. Further, as shown in FIG. 5, the balancer plate 35 may be made of a base material 45a as a metal material and only a portion 45b with which the balancer ball 34 abuts as a resin material by outsert molding or the like. The balancer plate 35 has a function as an autobalancer together with the balancer ball 34. The upper lid 36 is formed in a substantially disc shape, and the hole 36 a is engaged with the column portion 31 c formed in the clamper body 31 and the hole 36 b is engaged with the shaft 33 c of the balancer holder 33, so that the balancer ball 34 and the balancer are fixed. The plate 35 is covered so as not to be detached from the balancer holder 33.
[0031]
Next, the operation of the disk device configured as described above will be described.
First, the disk 40 is placed on the alignment ring 24 of the turntable 20. Next, the clamper 30 is attracted to the cap 25 of the turntable 20 by the magnet 32, and the lower end surface 31 d of the clamper 30 presses the disk 40 against the urging force of the alignment ring 24 by the spring 23, and the disk 40 is pressed. It is sandwiched between the turntable 20 and the clamper 30.
Next, when the disk 40 is rotated by the spindle motor 10 and the disk 40 has an eccentric center of gravity, the balancer balls 34 gather in a part of the annular groove 33 b of the balancer holder 33. At this time, since the balancer plate 35 is disposed between the balancer balls 34, collision between the balancer balls 34 is prevented.
[0032]
Next, an embodiment (2) of the disk device according to the present invention will be described. 6 to 8 show the embodiment (2) of the disk device according to the present invention. In addition, the description similar to Embodiment (1) is abbreviate | omitted by attaching | subjecting the same code | symbol.
[0033]
The disk device 150 of this embodiment (2) has a configuration in which the balancer holder 33, balancer balls 34, and balancer plate 35 of the disk device 100 of the embodiment (1) are provided on the turntable 20 side. As shown in FIG. 7, the turntable 60 of the embodiment (2) includes a balancer holder 68, a balancer plate 67, a balancer ball 34, a turntable body 61, a ring sheet 22, a spring 23, an alignment ring 24, and a cap 65. It is composed of The balancer holder 68 is formed in a substantially disc shape, and is formed with an annular groove 68a in which the balancer ball 34 is movably disposed, and a through hole 68b. The balancer plate 67 is formed in substantially the same shape as the balancer plate 35 except for the holes 67e. The turntable body 61 is formed in a substantially disc shape, and protrudes downward from the bottom to form a cylindrical portion 61a. The rotation shaft 11 of the spindle motor 10 is fitted in the through hole 61b of the cylindrical portion 61a, and the center portion is formed. The balancer plate 67 is rotatably supported through the hole 67e of the balancer plate 67, the stepped portion 61c of the cylindrical portion 61a is fitted into the hole 68b of the balancer holder 68, and the balancer is supported by the column portion 61d. The circumferential portion is fixed by engaging with the hole 68 c of the holder 68. The cap 65 is formed in substantially the same shape as the cap 25 except for the step portion 65b and the inclined portion 65c of the through hole 65a. The clamper 70 of the embodiment (2) is composed of a clamper main body 73, a magnet 32 and an upper lid 71. The clamper main body 73 is formed in a substantially disc shape, and has a central hole 73 a and a stepped portion 73 b to which the magnet 32 is fixed. The upper lid 71 is formed in a substantially disc shape, and includes a protrusion 71 a that fits with a step portion 65 b of the through hole 65 a of the cap 65, a column portion 71 b that engages with the hole 73 c of the clamper main body 73, and the clamper main body 73. A hole 71c that engages with the protrusion 73e is formed.
[0034]
In the above embodiment, the disk device using the alignment ring and the spring (alignment mechanism) is shown, but the present invention can also be applied to a disk device without an alignment mechanism.
[0035]
In addition, thin disk devices for so-called notebook personal computers do not correspond to the clampers shown in the embodiments, and there are disk devices having a chucking mechanism on a turntable. It is.
[0036]
Further, the present invention can also be applied to a disk device that employs CLV by setting the resonance frequency of a vibration system composed of a mechanical chassis and an insulator to be sufficiently low with respect to the necessary minimum rotational speed of CLV.
[0037]
【The invention's effect】
As described above, according to the present invention, when the disc and the clamper / turntable are rotated together by the spindle motor, a plurality of balancer balls are collected in a part of the annular groove when the disc has an eccentric center of gravity. The eccentric center of gravity is canceled. At this time, in order to avoid the collision between the balancer balls by the balancer plate arranged between the balancer balls, the balancer ball moves smoothly compared to the balance ball that includes a spring, and It is possible to provide a disk device that prevents collision noise between highly reliable balancer balls that does not cause disturbance vibration.
[0038]
Compared to the case where liquid is injected into an annular groove in which the balancer ball is movably disposed, packing parts are not required and assembly work is easy, so that a low-cost and highly reliable balancer can be obtained. It is possible to provide a disk device that prevents collision noise between balls.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing an embodiment (1) of a disk device according to the present invention.
FIG. 2 is an exploded view of a turntable in the disk device of FIG.
FIG. 3 is an exploded view of a clamper in the disk device of FIG. 1;
4 is a front view of a clamper in the disk device of FIG. 1. FIG.
FIG. 5 is a view showing another balancer plate of the clamper in the disk device of FIG. 1;
FIG. 6 is a side sectional view showing the embodiment (2) of the disk drive according to the present invention.
7 is an exploded view of a clamper in the disk device of FIG. 2;
8 is a front view of a clamper in the disk device of FIG. 2. FIG.
FIG. 9 is a side sectional view showing a conventional disk device.
FIG. 10 is a diagram showing a state (vibration system) in which a conventional disk device main body (including a mechanical chassis) is attached to a mechanical base.
11A is a diagram schematically showing the vibration system of FIG. 10 (when ω << ω0). FIG.
(B) A diagram schematically showing the vibration system of FIG. 10 (when ω = ω0).
(C) It is a figure which shows the vibration system of FIG. 10 typically (at the time of (omega) >> omega0).
FIG. 12 is a diagram showing a conventional disk device (conventional example 1).
FIG. 13 is a diagram showing a conventional disk device (conventional example 2).
[Explanation of symbols]
10 Spindle motor
11 Rotating shaft
20, 60 turntable
21 Turntable body
22 Ring sheet
23 Spring
24 alignment ring
25 cap
30, 70 Clamper
31 Clamper body
32 Magnet
33 Balancer holder
34 Balancer Ball
35 Balancer board
36 Upper lid
40 discs
100, 150 disk devices

Claims (3)

A disk apparatus comprising: a spindle motor; a turntable fixed to a rotating shaft of the spindle motor; and a clamper that holds the disk between the turntable and rotates integrally with the disk. In
The clamper includes a plurality of balancer balls that are movably disposed in an annular groove of a balance holder that is formed around the rotation axis of the spindle motor, and a balancer plate that is disposed between the balancer balls.
The balancer plate is comprised of a plurality, the about the axis of the balance holder is rotatably light fitted to each independently, each balancer plate, wherein with each balancer balls a function as automatic balancers A disk unit. In a disk device comprising: a spindle motor; a turntable fixed to a rotating shaft of the spindle motor; and a clamper that holds the disk between the turntable and rotates integrally with the disk.
The turntable includes a plurality of balancer balls that are movably disposed in an annular groove of a balance holder that is formed around the rotation axis of the spindle motor, and a balancer plate that is disposed between the balancer balls. ,
The balancer plate is comprised of a plurality, the about the axis of the balance holder is rotatably light fitted to each independently, each balancer plate, wherein with each balancer balls a function as automatic balancers A disk unit.   3. The disk device according to claim 1, wherein the balancer plate is formed of a resin material at least a portion where the balancer ball contacts.

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