JP2002148134A - Disc device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically correct an imbalance of a rotational system including the imbalance of a disc with ease over a wide number of revolutions and usage. SOLUTION: For correcting an imbalance in rotation of an optical disc 21 placed on a turntable 10, an imbalance correcting mechanism 22 is arranged. The imbalance correcting mechanism 22 is constructed of an annular hollow part 23 arranged around a rotary shaft 15 and a plurality of spherical correction bodies 24 freely moving inside the annular hollow part 23. A moving member 26 freely movable in the radial direction of the turntable 10 is arranged, and when the number of revolutions of the optical disc 21 exceeds a predetermined number, the moving member 26 is protruded into the annular hollow 23 by centrifugal force for restricting motion of the spherical correction bodies 24. In this case, a latch member 28 is engaged in an engaging hole 26B of the moving member 26, and motion of the spherical correction bodies 24 is kept restricted even when the number of revolutions of the optical disc 21 is lowered below the predetermined number.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive, and more particularly, to a disk drive having a function of suppressing undesired vibration and noise due to imbalance of a recording medium and enabling stable recording and reproduction.

[0002]

2. Description of the Related Art Disc-shaped interchangeable recording media are
A disk device for recording and reproducing data is an external device such as a personal computer (hereinafter, referred to as a PC).
Alternatively, it is used by being built in a PC or the like. In recent years, as such a disk device, a multi-media system that handles a large amount of data has been developed to use a CD-ROM, a DVD-ROM,
An optical disk device using an optical disk such as a VD-RAM has attracted attention. As multimedia becomes more advanced, it is necessary to record and reproduce a large amount of data such as still images and moving images with an optical disk, and in recent optical disk devices, the disk rotation speed has been increasing.

[0003] However, there is a major problem that must be overcome in order to increase the disk rotation speed. That is, when the disk rotation speed is increased, the unbalanced vibration of the optical disk increases. In an optical disk device such as a CD-ROM, a hard disk device (HDD)
Unlike the optical disk, the optical disk is interchangeable. Because such exchangeable optical disks are mass-produced by pressing,
Some discs have large variations in disk thickness and large variations in concentricity between the clamp inner diameter and the disk outer shape. Also, the imbalance in weight caused by printing characters and patterns on the optical disk cannot be ignored.

[0004] When a system having a large unbalance is rotated, an unbalance vibration is generated due to the fact that the center of gravity of the rotating system does not coincide with the center of rotation. The force F for generating the unbalanced vibration is expressed by the following equation, where ε is the distance between the center of gravity and the center of rotation, m is the mass of the rotating body, and ω is the number of rotations. F = m × ε × ω ² ............ (1)

[0005] As shown in equation (1), the unbalanced vibration is proportional to the square of the number of rotations. Unbalance vibration not only excites the optical head system and hinders reading / writing of signals, but also causes noise and vibrates the system itself in which the device is installed, causing a significant reduction in the reliability of the system itself. Become. Therefore, in order to achieve high-speed rotation of the disk, it is necessary to suppress undesired vibration due to unbalance of the disk.

Conventionally, an example of a disk device that suppresses vibrations caused by such disk imbalance is disclosed in Japanese Patent Application Laid-Open No. Hei 10-83622. In this publication, for example, a balancer is formed by housing a plurality of spheres or liquid compensators inside a hollow annular portion, and the balancer is rotated integrally with the disk, thereby achieving high-speed rotation of an unbalanced disk. It has been proposed to suppress vibration generated during rotation.

[0007]

However, in the above-mentioned prior art, the above-mentioned conventional technology functions at a rotational frequency higher than the natural frequency in the plane where the unbalance of the supporting system supporting the rotating system acts, but the characteristic of the supporting system is It is difficult to keep the corrector in the hollow annular portion at a position that balances the imbalance in the rotational frequency range near or below the frequency.

A PC equipped with a recently developed DVD (Digital Versatile Disk) uses a conventional CD-ROM.
It is also required that the ROM can be reproduced without any trouble at a high rotation speed, and can be reproduced without any trouble at various selected rotation speeds. In particular, it is necessary to keep the balance close to the resonance frequency of the rotating system. Further, depending on the configuration of the device, it is necessary to be able to cope with the case where the device is placed horizontally or vertically.

It is an object of the present invention to provide a disk device capable of easily and automatically correcting imbalance of a rotating system including disk imbalance in a wide range of rotation speeds and applications.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a rotatable turntable on which a disk-shaped recording medium is placed, and a rotating drive of the turntable to rotate the recording medium. Driving means for rotating about an axis;
A head for recording and reproducing data to and from the recording medium; and an unbalance correction mechanism for correcting imbalance during rotation of the recording medium, wherein the unbalance correction mechanism is a plane perpendicular to the rotation axis. An annular cavity portion provided around the rotation axis therein, a plurality of correction bodies for freely moving inside the annular cavity portion to correct imbalance, and a predetermined rotation speed of the turntable. When the number is exceeded,
Limiting means for restricting the movement of the corrector in the annular cavity and maintaining the restricted state.

According to the above arrangement, when the disk is mounted on the turntable and the disk rotates at a predetermined rotation speed or less, the correction member moves freely in the annular cavity. When rotating at a speed exceeding
The restricting means restricts the movement of the compensator in the annular cavity so that the compensator cannot move freely in the annular cavity. Then, the limiting means holds the state in which the movement of the correction body is limited, and holds this state even when the rotation speed of the disk decreases. For this reason, even if the rotation speed of the disk is reduced to near or even below the rotation frequency corresponding to the resonance frequency,
The compensator cannot move freely in the annular cavity,
As a result, the disk stops at a narrow area in the annular cavity, and vibration due to imbalance of the disk can be suppressed.

The limiting means has a plurality of moving members movable in a radial direction, and when the rotation speed of the turntable exceeds a predetermined rotation speed, the moving member moves radially outward by centrifugal force. The annular cavity is divided into a plurality of regions. Thereby, the movement of the correction body can be restricted.

The limiting means has a plurality of moving members movable in a radial direction, and when the rotation speed of the turntable exceeds a predetermined rotation speed, the moving members move radially outward by centrifugal force. Then, the corrector is pressed against the outer side wall of the annular cavity. Thereby, the movement of the correction body can be restricted.

Further, a release means for releasing the state in which the movement of the correction body is restricted can be provided.

Further, it is possible to provide a rotation speed control means for rotating the turntable beyond the predetermined rotation speed after placing the recording medium on the turntable, and thereafter reducing the rotation speed to the predetermined rotation speed or less. .

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 is a perspective view showing the internal configuration of the disk device according to the present invention. As shown in FIG. 4, the disk device 1 includes a mechanical chassis 2 and a mechanical unit 3, and the mechanical unit 3 is fixed to the mechanical chassis 2 via an elastic support member 4. In the mechanical unit 3,
A drive system including a spindle motor 5, a slide motor 6, and the like, and an optical system including an optical head 7 and the like are attached. Components that can be a vibration source are integrated in the mechanical unit 3. The optical head 7 is configured to move to the inner circumference or the outer circumference of the optical disk by the slide motor 6 along the main guide 8 and the sub guide 9. Note that a turntable 10 is attached to the spindle motor 5.

(Embodiment 1) FIGS. 1 to 3 are longitudinal sectional views of a disk drive device according to Embodiment 1; FIG. 1 shows a state where an optical disk is not mounted, and FIG. 2 shows a state where an optical disk is mounted. FIG. 3 shows a state where the mounted optical disk is rotated at a high speed. This disk drive is mounted on the disk device shown in FIG.

In FIG. 1, a spindle motor 5 has a stator 11 and a motor rotor 12, and a motor substrate 1
3 and is fixed on the mechanical unit 3. A bearing 14 is incorporated in the motor substrate 13, and a shaft (rotating shaft) 15 of the spindle motor 5 is rotatably supported on the bearing 14. The motor rotor 12 is mounted on a shaft 15. The motor rotor 12 is formed in a cylindrical shape, and has a multi-polarized drive magnet 16 provided therein. The drive magnet 16 is arranged to face the stator 11 fixed together with the bearing 14 on the motor board 13. That is, in the present embodiment, the spindle motor 5 is configured as an outer rotor type.

The turntable 10 is a spindle motor 5
It is provided above. The turntable 10 is provided with a centering bracket 17 and a moving bracket 18 arranged outside the centering bracket 17 at the center thereof. The centering bracket 17 is formed in a circular shape as shown in FIG. 5, and has a shaft hole 17A through which the shaft 15 of the spindle motor 5 is inserted and fixed, and a lower flange 17B at the lower portion. ing. Moving bracket 1
8 is formed in an annular shape as shown in FIG. 6, and a lower flange 18A whose peripheral edge is folded is provided at a lower portion thereof. The lower flange 18A is formed with a hole 18C through which a distal end of a latch member 28 described later is inserted. The outer peripheral surface of the centering bracket 17 is provided with four grooves 17C along the axial direction.
8, four ridges 18B are formed along the axial direction on the inner peripheral surface of the ring. When the centering bracket 17 is inserted into the ring of the moving bracket 18 as shown in FIG. The ridge 18B is fitted. That is, the groove 17C and the ridge 18B function as splines, whereby the moving bracket 18 rotates together with the centering bracket 17 when rotating around the shaft 15, but in the axial direction along the shaft 15 (up and down in FIG. 1). Direction) can be moved alone. A driving spring 19 is provided between the lower flange 17B of the centering bracket 17 and the upper part of the moving bracket 18 inside the ring of the moving bracket 18, and the moving bracket 18 is urged upward in the drawing by the driving spring 19. ing.

On the upper part of the centering bracket 17,
A clamp magnet 20 for centering and holding the optical disk via a moving bracket 18 is embedded therein.
When the optical disc is placed on the turntable 10, the optical disc 21 is fixed at a predetermined position as shown in FIG. 2 by the magnetic attraction acting between the clamp magnet 20 and a clamper (not shown).

An unbalance correction mechanism 22 is provided on the outer periphery of the turntable 10. As shown in FIG. 8, the unbalance correction mechanism 22 includes an annular cavity 23 provided around the rotation shaft 15 and a plurality of spherical correctors 24 housed inside the annular cavity 23. Have. The annular hollow portion 23 includes an outer peripheral wall 10A of the turntable 10 and an inner peripheral wall 10B formed inside the outer peripheral wall 10A. The spherical corrector 24 includes the outer peripheral wall 10A and the inner peripheral wall 10B.
Along the inside of the annular hollow portion 23. In addition, four moving members 26 that are movable in the radial direction are provided inside the annular hollow portion 23. The moving member 26 has a flange 26A formed on the side near the rotation shaft 15, and a holding spring 27 is provided between the flange 26A, the bottom 10C of the turntable 10, and the centering bracket 17. And moving member 2
6 is pressed against the lower outer peripheral surface of the centering bracket 17 by the holding spring 27.

As shown in FIG. 7, an engagement hole 26B is formed on the upper surface of the moving member 26. On the other hand, the lower flange 18A of the moving bracket 18 is provided with a latch member 28.
Are provided movably in the vertical direction. This latch member 28 has a flange 28A at the upper part,
Hole 18C formed in lower flange 18A (see FIG. 6)
Has been inserted. Further, the latch member 28 is urged downward by a latch pressurizing spring 29 attached to an upper portion thereof. FIG. 7 shows only the left half of the turntable 10, and the right half is omitted.

In this embodiment, the spindle motor 5 constitutes a driving means, and the moving member 26, the latch member 28 and the like constitute limiting means.

The operation when the optical disk 21 is rotated with the optical disk 21 mounted on the turntable 10 in the above configuration will be described with reference to FIGS. When the optical disk 21 is placed on the turntable 10, the moving bracket 18 is pushed down against the urging force of the drive spring 19 by the electromagnetic force acting between the clamp magnet 20 and a clamper (not shown). The end surface is positioned in contact with the lower flange 17B of the centering bracket 17. Along with the movement of the moving bracket 18, the latch member 28 also moves downward by the urging force of the pressurizing spring 29, and its tip hits the upper surface of the moving member 26. When the disk 21 having an unbalance is rotated with respect to the rotation center of the shaft 15 from such a state, the vibration in the in-plane direction of the optical disk acts on the spindle motor 5 and the mechanical unit 3 as shown in FIG. And mechanical unit 3
Is elastically supported on the mechanical chassis 2 by the elastic support member 4, so that it oscillates and vibrates mainly at a frequency corresponding to the rotational speed in the in-plane direction of the optical disk 21, and the spindle motor 5 is also integrated with the mechanical unit 3. Vibrate.

This vibration system has a resonance frequency ωn determined by the spring constant of the elastic support member 4 and the mass of the mechanical unit 3 and the objects mounted on the mechanical unit 3. Therefore, when the rotation speed is equal to or lower than the resonance frequency, the position of the whirling center is oriented in the same direction as the unbalance, and at a rotation speed higher than the resonance frequency, the position is opposite to the unbalance direction.

In the configuration of the present embodiment, once the rotational speed is higher than the resonance frequency, the spherical corrector 24 in the annular cavity 23 moves to a position that balances the imbalance of the rotating system and stabilizes. . Further increase the rotation speed,
When the centrifugal force acting on the moving member 26 becomes equal to or greater than the urging force of the holding spring 27, the moving member 26 separates from the lower outer peripheral surface of the centering bracket 17 and moves away from the holding spring 27.
And move radially outward. And
The tip of the moving member 26 protrudes into the annular cavity 23 from an opening provided on the inner peripheral side of the annular cavity 23, and divides the annular cavity 23 into a plurality of regions. At the same time, the tip of the latch member 28 urged by the pressurizing spring 29 engages with the engagement hole 26B on the surface of the moving member 26, and the moving member 2
6 is fixed.

FIG. 8 shows that the moving member 26 is
Is divided into a plurality of regions, (a) is a longitudinal sectional view of the disk drive device, and (b) is a sectional view taken along line AA of (a). As shown in FIG. 8, in the high-speed rotation region, when the plurality of moving members 26 protrude from the inner periphery of the annular cavity 23 to form a partition, the annular cavity 2
3 is divided into a plurality of areas. From this state, when the rotation speed of the optical disk 21 decreases and the rotation speed becomes lower than the resonance rotation speed, the spherical corrector 24, which is stationary in the annular cavity 23 divided by the moving member 26, (B)
Move in the direction of the arrow A or the arrow B toward the unbalance direction G shown in FIG. 3, but the movement is restricted by hitting the moving member 26 protruding from the annular cavity 23. Because its movement range is limited to the divided annular cavity,
The whirling vibration can be reduced even in the rotation frequency region below the resonance frequency.

When the optical disk 21 is removed from the disk device, the moving bracket 18 is pushed up by the drive spring 19 and the lower flange 18 of the moving bracket 18 is moved.
A comes into contact with the flange 28A of the latch member 28, and pushes the latch member 28 up against the urging force of the pressurizing spring 29, so that the latch member 28 is disengaged from the engagement hole 26B of the moving member 26, and the latch member 28 is moved. The member 26 returns to the initial position by the urging force of the holding spring 27.

While the above description has been given of the operation in the case where the unbalanced disk is mounted and driven, the centrifugal force acting on the moving member overcomes the pressurized spring force even in the case of a disk having a small unbalance. Is accelerated up to the preset rotation speed as
The vibration can be reduced by moving the position of the correction body 24 inside to a position where the balance is imbalanced, and then reducing the rotational speed to the target rotational speed.

(Embodiment 2) Next, a disk drive device according to Embodiment 2 of the present invention will be described. FIG. 9 is a longitudinal sectional view of the disk drive device, and FIG.
It is sectional drawing along the line. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the present embodiment, instead of the moving member 26 in the first embodiment, four plate-shaped magnetic members 31 spreading in a fan shape from the inner peripheral side to the outer peripheral side are provided in the radial direction of the turntable 10. The magnetic member 31 is provided with a non-magnetic elastic member 32 which is more easily deformable than the magnetic member 31. A permanent magnet 33 having an annular cross section is fixed to a lower outer peripheral surface of the centering bracket 17, and an inner peripheral side of the magnetic member 31 is attracted to the permanent magnet 33. The upper surface of the magnetic member 31 has an engagement hole 31.
A is formed.

The lower flange 18A of the moving bracket 18
Is provided with a latch member 34 corresponding to the engagement hole 31A of the magnetic member 31. The latch member 34 is vertically movable, and a flange is formed on an upper portion thereof. The latch member 34 has the same shape as the latch member 28 of the first embodiment, but is formed of a non-magnetic material. The latch member 34 is also urged downward by the pressurizing spring 29. Reference numeral 35 denotes a regulating member that regulates the magnetic member 31 from shifting in the circumferential direction of the turntable 10, and is fixed to the bottom 10C of the turntable 10. In the present embodiment, the magnetic member 31
The latch member 34 and the like constitute limiting means.

The operation when the optical disc 21 is mounted on the turntable 10 and the optical disc 21 is rotated in the above configuration will be described with reference to FIGS. When the optical disc 21 is placed on the turntable 10, the moving bracket 18 is pushed down by the electromagnetic force acting between the clamp magnet 20 and a clamper (not shown) as in the first embodiment. When the turntable 10 is rotated in this state, and the rotation speed of the optical disk 21 reaches or exceeds the resonance frequency of the support system, the magnetic member 31 that has been attracted to the permanent magnet 33 is separated from the permanent magnet 33 by centrifugal force, and further turned. The radial movement of the table 10 causes the elastic member at the peripheral edge of the magnetic member 31 to hit the spherical corrector 24 as shown in FIG. Constrain the movement of

At the same time, the latch member 34 is engaged with the engagement hole 31A provided on the upper surface of the magnetic member 31 to fix the magnetic member 31. As a result, even if the rotation speed of the optical disk 21 is reduced to fall below the resonance frequency of the support system, the magnetic member 3
1 is to keep the position at the time of high-speed rotation because the movement in the radial direction is restricted by the latch member 34, and to keep the spherical corrector 24 at a position where it is unbalanced,
Vibration due to whirling can be reduced. The operation after the removal of the optical disk 21 is the same as that of the first embodiment.

[0035]

As described above, according to the present invention, when the rotation speed of the turntable exceeds a predetermined rotation speed, the movement of the compensator in the annular cavity is restricted. Even if the number is less than the limit, the restricted state is maintained, so the vibration of the mechanical unit due to the imbalance of the optical disk can be reliably reduced, and the unbalanced disk can be rotated regardless of whether the device is placed horizontally or vertically. However, stable recording or reproduction is possible.

Further, it is possible to realize a disk device in which low vibration is maintained from a high speed range to a low speed range and high-speed data transfer is possible.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a disk drive device according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view when an optical disk is placed on the disk drive device of FIG.

FIG. 3 is a longitudinal sectional view when an optical disk is mounted on the disk drive device of FIG. 1 and rotated at a high speed.

FIG. 4 is a perspective view showing the internal configuration of the disk device of the present invention.

FIG. 5 is a plan view of a centering bracket that is one of the components of the disk drive device of FIG. 1;

FIG. 6 is a plan view of a moving bracket which is one of the components of the disk drive device of FIG. 1;

FIG. 7 is an enlarged view of the left half of the turntable.

FIGS. 8A and 8B are diagrams for explaining the operation of the disk drive device according to the first embodiment of the present invention, wherein FIG. 8A is a longitudinal sectional view of the disk drive device, and FIG. It is sectional drawing along.

FIG. 9 is a longitudinal sectional view of a disk drive according to a second embodiment of the present invention.

FIG. 10 is a cross-sectional view taken along the line AA of FIG.

FIG. 11 is a longitudinal sectional view when an optical disk is placed on the disk drive device of FIG. 9;

12 is a longitudinal sectional view when an optical disk is mounted on the disk drive device of FIG. 9 and rotated at a high speed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disk device 2 Mechanical chassis 3 Mechanical unit 4 Elastic support member 5 Spindle motor 6 Slide motor 7 Optical head 10 Turntable 10A Outer peripheral wall 10B Inner peripheral wall 10C Bottom part 11 Stator 12 Motor rotor 13 Motor substrate 14 Bearing 15 Shaft 16 Drive magnet 17 Centering bracket 17B Lower Flange 18 Moving Bracket 18A Lower Flange 19 Drive Spring 20 Clamp Magnet 21 Optical Disk 22 Unbalance Correction Mechanism 23 Circular Cavity 24 Spherical Corrector 26 Moving Member 26A Engagement Hole 27 Holding Spring 28 Latch Member 29 Pressing Spring 31 Magnetic Member 31A Engagement hole 32 Elastic member 33 Permanent magnet 34 Latch member

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 5/24 H02K 7/04 7/04 F16F 15/32 K (72) Inventor Yoshihiro Sato Tsuchiura-shi, Ibaraki 502, Kachimachi-cho, Machinery Research Laboratory, Hitachi, Ltd. BB14 BB19 DD09 5H607 AA04 AA12 BB01 BB07 BB09 BB14 BB17 BB25 CC01 CC03 CC05 DD14 EE38 FF12

Claims (5)

[Claims] 1. A rotatable turntable on which a disk-shaped recording medium is placed, and driving means for rotating the turntable to rotate the recording medium about a rotation axis;
A head that performs recording and reproduction of data with the recording medium, and an unbalance correction mechanism that corrects imbalance during rotation of the recording medium, wherein the unbalance correction mechanism is a plane perpendicular to the rotation axis. An annular cavity portion provided around the rotation axis therein, a plurality of correction bodies for freely moving inside the annular cavity portion to correct imbalance, and a predetermined rotation speed of the turntable. Limiting means for restricting the movement of the correction body in the annular cavity when the number exceeds the number, and holding the restriction state. 2. The disk device according to claim 1, wherein said limiting means has a plurality of moving members movable in a radial direction, and said moving means is provided when a rotation speed of said turntable exceeds a predetermined rotation speed. A disk device, wherein a member moves radially outward by centrifugal force to divide the annular cavity into a plurality of regions, thereby restricting the movement of the correction body. 3. The disk device according to claim 1, wherein said limiting means has a plurality of moving members which are movable in a radial direction, and said moving means moves when a rotation speed of said turntable exceeds a predetermined rotation speed. A disk device, wherein a member moves radially outward by a centrifugal force and presses the correction body against an outer peripheral wall of the annular cavity, thereby restricting movement of the correction body. 4. The disk device according to claim 1, further comprising a release unit configured to release a state in which the movement of the correction body is restricted. 5. The disk device according to claim 1, wherein the recording medium is placed on the turntable, and then the turntable is rotated at a speed exceeding the predetermined number of revolutions. A disk device comprising a rotation speed control means for decelerating to a rotation speed or less.