JPH11154371A - Disk driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce vibration and noise even when a recording disk large in deviation center of gravity at the time of high speed rotation is rotated by providing a catching part catching a ball for compensating dynamic balance in an inner peripheral part side of a ring groove. SOLUTION: Plural small protrusion 15 are formed on an outer peripheral part of a guide ring 10 engaged with an inner wall part of a ring groove 8 in the direction of ring width. When acceleration is performed from low speed rotation, balls 9 which are collected downside by gravity are rotated together with a turn table 1 by frictional force between the balls and the wall of the ring groove 8, and moved upward of the ring groove 8, but at the time of low speed rotation, the balls 9 are returned to the original downside by gravity even when desire to lift upward since the frictional force is small. A dropping ball 9 is caught by the protrusion 15 by attaching the guide ring 10 having the protrusion 15 to an inner peripheral wall of the ring groove 8, the ball is lifted upward again by rotation of the turn table 1, and the ball 9 is made easy to carry upward.

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 provided with means for correcting dynamic balance.

[0002]

2. Description of the Related Art In recent years, the number of revolutions of a recording disk has been remarkably increased as the reproduction signal of the recording disk has been broadened. In particular, in a CD-ROM device, the recording disk rotates at a high speed of 7000 to 8000 rpm. At that time, in the case of a recording disk with a good weight balance, no vibration occurs even when rotated at high speed, but the recording disk with a poor weight balance or the recording disk is mounted eccentrically with respect to the center of rotation even if the balance is good. If
Vibration occurs due to the displacement between the center of rotation and the center of gravity of the disk. Since the excitation force of this vibration is proportional to the square of the rotation speed,
High-speed rotation produces large vibrations and causes noise.

As means for automatically correcting such a deviation (center of gravity) between the center of rotation and the center of gravity of the disk, a plurality of metal balls rotating around the center of rotation of the disk are inserted into the inside of the disk drive. The so-called ball balancer device, which sets the natural frequency including the rotation system lower than the rotation frequency and utilizes the characteristic that the balls gather in the eccentric direction during high-speed rotation, is called "vibration control" JOHN N. MAC
DUFF JOHNR. CURRERI, published by Cocorona P. 258-266. However, the conventional ball balancer has the following problems.

[0004]

That is, when the disk drive is placed vertically (when the disk surface is vertical), when the balls gather at the time of rest due to the effect of gravity and the disk drive is placed horizontally. In comparison, the balance cannot be obtained unless the rotation speed is higher. In addition, the balance is not improved not only at the time of high-speed rotation but also at the time of low-speed rotation, and at this time, the sliding noise of the ball due to the relative rotation of the ball and the rotating body is generated and becomes noise.

In order to correct the balance, it is necessary for the ball to rotate smoothly with low friction. However, the friction against the ball increases due to the following reasons, and the correction ability is reduced. That is, the ball is pressed against the side wall of the ring groove during rotation and rotates. For this reason, the side wall of the ring groove is dented by the Hertz force, and the friction increases. Since this pressing force is a centrifugal force, the friction further increases during high-speed rotation. In addition, the ball contacts the ring at two points, the side wall and the bottom surface, so that not only a pure rolling motion but also a slip occurs, so that the friction increases.

Further, the friction accompanying the rotation of the ball is small,
When the eccentricity of the recording disk is small, the ball causes self-excited vibration, which causes a phenomenon that the relative rotation between the ball and the rotating body is difficult to stop.

An object of the present invention is to solve such a disadvantage of the prior art, and to provide an inexpensive disk drive capable of greatly reducing vibration and noise even when a recording disk having a large center of gravity shift is driven at high speed rotation. To provide.

[0008]

According to the present invention, a ring groove is provided around the center of rotation of a shaft, a ball for dynamic balance correction is movably inserted into the ring groove, and is inserted into an opening of the ring groove. It is intended for a disk drive device provided with a lid.

In order to achieve the above object, a first aspect of the present invention is to provide a method in which the dynamic balance correction ball is caught on the inner peripheral side of the ring groove by, for example, a projection, unevenness, or a member having a large friction coefficient. It is characterized by having been provided.

In order to achieve the above object, a second aspect of the present invention is to provide, for example, a projection, unevenness, or a member having a large friction coefficient in which the dynamic balance correction ball is caught on the side of the lid facing the dynamic balance correction ball. A catch portion is provided.

According to a third aspect of the present invention, there is provided a vibration damping means comprising, for example, a lubricant film for damping the vibration of the dynamic balance correcting ball. It is characterized by having.

According to a fourth aspect of the present invention, the outer peripheral portion of the ring groove has a conical surface shape extending in a direction away from the groove bottom surface, and a guide ring is provided on an inner peripheral portion of the ring groove. It is characterized by being fitted.

In order to achieve the above object, a fifth aspect of the present invention is characterized in that an annular groove extending in a circumferential direction is formed on an outer peripheral portion of the ring groove.

In order to achieve the above object, a sixth aspect of the present invention is characterized in that a hard layer is formed on the inner surface of the ring groove by, for example, chrome plating.

In order to achieve the above object, a seventh aspect of the present invention is characterized in that the ring groove is formed on the disk mounting surface side of the turntable.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, according to the first aspect of the present invention, the provision of a hook portion on the inner peripheral side of the ring groove facilitates the rotation of the ball even when the apparatus is placed vertically. Balance correction can be performed even at relatively low speed rotation.

According to the second aspect of the present invention, as described above, the provision of the catch on the lid promotes the rotation of the ball even when the apparatus is placed vertically, and performs the balance correction even at a relatively low speed. be able to.

According to the third aspect of the present invention, as described above, since the vibration damping means is provided inside the ring groove, the oscillation phenomenon of the ball in the ring groove is suppressed, and the balance adjustment is smoothly performed. be able to.

According to the fourth aspect of the present invention, as described above, by forming the outer peripheral portion of the ring groove into a conical shape, the ball floats from the groove bottom surface and rotates in a state close to a pure rolling motion. Is extremely small, the ball moves lightly, and the balance correction ability increases when used in combination with the guide ring.

According to the fifth aspect of the present invention, as described above, since the annular groove is formed on the outer peripheral portion of the ring groove, when the ball floats from the groove bottom surface and is caught by the annular groove, the ball is close to a pure rolling motion. , So the friction is extremely small,
The ball moves lightly and the balance correction ability increases.

According to the sixth aspect of the present invention, since the hard layer is formed on the inner surface of the ring groove and the surface hardness is increased as described above, the number of dents due to the ball is reduced and the coefficient of friction is reduced. Yes, the balance correction ability increases.

According to the seventh aspect of the present invention, as described above, since the ring groove is formed on the disk mounting surface side of the turntable,
The same chucking process or molding with the same mold as the guide part of the center hole of the turntable disk is possible, the rotational runout of the outer circumference of the ring groove is reduced, the dynamic balance of the disk drive is reduced, and vibration and noise are reduced. Can be reduced.

Next, an example in which the embodiment of the present invention is applied to a disk drive for a CD-ROM will be described with reference to the drawings. 1 is a sectional view of the disk drive, FIG. 2 is a schematic configuration diagram showing a support structure of the disk drive, and FIG. 3 is an enlarged sectional view of a ring groove.

In these figures, reference numeral 1 denotes a turntable which is press-fitted into a shaft 2 and rotates integrally therewith.
Is rotatably supported by two bearings 3 provided in a case 4. A stator 5 is attached to an outer peripheral portion of the case 4, and a rotor magnet 6 adhered to a metal case 7 is attached to an outer peripheral portion of the turntable 1, and is turned by a motor composed of the stator 5 and the rotor magnet 6. The table 1 rotates. The recording disk 12 is placed on the sheet 13, fitted on the central projection of the turntable 1, and pressed against the turntable 1 by the cap 14.

A ring groove 8 having a center of rotation as a center is formed on the outer peripheral upper surface of the turntable 1, that is, on the disk mounting surface side, and a plurality of metal balls 9 are rotatably inserted therein. A guide ring 10 is provided on the inner wall of the ring groove 8.
The upper portion of the ring groove 8 is covered with a lid 11 to prevent the ball 9 from jumping out.

The disk drive 101 is thus constructed, and as shown in FIG. 2, the disk drive 101 is fixed to a chassis 103 having a pickup and a feed mechanism (both not shown). The chassis 103 is attached to a frame 104 via a damper rubber 105. Due to such a structure, when the recording disk 102 whose center of gravity is shifted with respect to the rotation center of the shaft 2 is mounted and rotated, an in-plane vibration force acts on the disk drive device 101 and the chassis 103, and the chassis 103
Is elastically supported on the frame 104 by the damper rubber 105, so that it oscillates and vibrates mainly at the rotational frequency in the in-plane direction of the disk, and the disk drive 10
1 also vibrates together with the chassis 103.

The vibration system includes a spring constant of the damper rubber 105 and the disk drive 101 and the chassis 103.
Has a resonance frequency determined by the mass of Due to this vibration, when the number of rotations increases, a deviation occurs between the whirling center and the rotation center of the turntable 1. This direction of displacement based on the direction of displacement of the center of gravity changes with an increase in the number of rotations,
At low speed rotation, the center of gravity shifts in the direction opposite to the center of gravity, and at rotations higher than the resonance frequency, the center of gravity shifts in the opposite direction. Therefore, when the rotation frequency is lower than the resonance frequency, a force in the direction of the shift of the center of gravity acts on the ball 9, and when the rotation frequency exceeds the resonance frequency, a force in the direction opposite to the direction of the shift of the center of gravity acts. With this force, the ball 9 acts in the direction of correcting the shift of the center of gravity, that is, the direction of correcting the balance. This is the principle of the ball balancer. Since the force acting on the ball is weak, it is necessary to minimize the friction against the operation of the ball.

FIG. 3 shows a sectional shape of the ring groove 8 for reducing the friction. During low-speed rotation, the ball 9 is at the position shown by the broken line in the figure due to gravity and centrifugal force, that is, at the position in contact with both the groove bottom surface and the outer peripheral surface. In this state, a pure rolling motion does not occur at both contact points, and the coefficient of friction does not decrease because of a motion state intermediate between rolling and sliding. Therefore, the lower part of the outer peripheral surface of the ring groove 8 and the vicinity of the portion where the ball 9 contacts in a broken line state are inclined in the direction in which the groove width increases as going upward, and this part of the outer peripheral surface becomes a conical surface as a whole. ing.

Since the ball 9 is pressed against the outer peripheral surface by centrifugal force, if the ball 9 is inclined as described above, a force for pushing the ball 9 upward is generated. At low speed rotation, the ball 9 is in the position indicated by the broken line due to static friction. However, at high speed rotation, the centrifugal force increases. At the position indicated by the solid line, the ball 9 rotates in contact with the outer peripheral surface without contacting the groove bottom surface.

When the angle formed by the oblique portion of the outer peripheral surface and the vertical direction is small, the ball 9 comes into contact with two extremely close points on the outer peripheral surface. This state is very close to the state where the ball 9 is in contact with one point on the wall, and therefore the ball 9 rotates in a state close to a pure rolling motion, so that the friction is extremely small and the ball 9
Moves lightly, and the balance correction ability increases. If the angle between the inclined surface and the vertical direction is large, the contact point with the ball 9 is separated and pure rolling friction is lost, so that the inclination angle cannot be made too large. Therefore, it is appropriate that the angle between the oblique portion of the outer peripheral surface and the vertical direction is in the range of 1 to 20 degrees.

The depth of the ring groove 8 (the distance from the lower surface of the lid 11 to the bottom of the groove) corresponds to a value obtained by adding the diameter of the ball 9 and the clearance. Since the ball 9 only needs to be slightly away from the groove bottom surface, it is sufficient that the maximum height of the inclined surface is の of the depth of the ring groove 8 even if the amount of deflection of the groove bottom surface is considered.
In this state, the clearances above and below the ball 9 are substantially equal.

FIG. 4 is a sectional view showing a second embodiment of the present invention. In this example, one or a plurality of annular grooves 16 such as V-shaped grooves or U-shaped grooves extending in the circumferential direction are formed on the outer peripheral surface of the ring groove 8. When the ball 9 is caught in the annular groove 16 as shown in FIG. 4 for some reason, the ball 9 is in a stable state and continues to rotate in this state, close to a pure rolling motion, and the coefficient of friction becomes extremely small.

As described above, the ball 9 rotates while being pressed against the wall of the ring groove 8 by the action of centrifugal force and gravity. Therefore, the wall is elastically recessed by the Hertz force, and the larger the recess, the greater the friction. This dent becomes smaller as the surface hardness of the wall increases,
The coefficient of friction decreases. Therefore, by forming a hard layer on the wall surface of the ring groove 8 by metal plating such as chrome plating, vapor deposition, sputtering, or the like, the surface hardness can be increased and the friction coefficient can be reduced. Forming a hard layer not only reduces the coefficient of friction, but also has the effect of preventing surface corrosion and extending the life of the entire device.

Next, the operation of the guide ring 10 will be described. FIG. 5 shows a state in which the ring groove 8 is viewed from a direction perpendicular to the disk surface with the disk drive device placed vertically.
FIG. 6 shows a perspective view of the guide ring 10. In FIG. 5, the downward direction is the direction of gravity. A plurality of small protrusions 1 are provided on the outer peripheral portion of the guide ring 10 fitted to the inner wall portion of the ring groove 8.
5 are formed in the direction of the ring width.

When accelerating from low-speed rotation, as shown in FIG. 5, the balls 9 are gathered downward by gravity. The balls 9 gathered below rotate together with the turntable 1 due to the frictional force with the wall of the ring groove 8 and try to be carried above the ring groove 8. Even if lifted, it often returns to its original lower part due to gravity. The lifted ball 9 falls while contacting the inner peripheral wall of the ring groove 8. Then the projection 15
When the guide ring 10 having the following is mounted on the inner peripheral wall of the ring groove 8, the falling ball 9 is caught by the projection 15 and is lifted up again by the rotation of the turntable 1,
The ball 9 is easily carried upward. When carried up,
The ball 9 falls in the rotation direction inside the groove, and the ball 9 starts rotating in the same direction with respect to the ring groove 8.

When the ball 9 is further accelerated, a centrifugal force acts on the ball 9, and the centrifugal force causes the ball 9 to move in the outer peripheral direction and rotate stably without contacting the projection 15.
When the guide ring 10 having the projections 15 is mounted on the inner peripheral wall of the ring groove 8 as described above, the balls 9 do not continue to gather downward even at a low speed due to the action of the projections 15. However, balance correction can be performed.

In the present embodiment, the guide ring 10 having the projections 15 is used. However, the guide ring 10 is provided with an infinite number of irregularities on the outer peripheral surface thereof to increase the coefficient of friction, or the guide ring 10 is made of rubber or the like. It is made of a material having a large coefficient, a rubber ring is fitted on the outer peripheral portion of the guide ring 10, a projection is provided on the inner peripheral wall of the ring groove 8 by omitting the guide ring 10, or the inner peripheral wall of the ring groove 8 is formed. Even if the surface roughness is increased to increase the friction coefficient, the same operation and effect as described above can be obtained.

Since the lid 11 shown in FIG. 1 serves as a side wall when the disk drive is placed vertically, the ball 9 also comes into contact with the lid 11. Therefore, by increasing the coefficient of friction of this portion with respect to the ball 9, the force for transporting the ball 9 from below to above can also be increased. For this reason, as shown in FIG. 7, the projections 17 are formed on the surface of the lid 11 which contacts the ball 9 or countless irregularities are formed to increase the friction coefficient. It is good to form with a material.

Further, as shown in FIG. 3, it is more effective to use both the guide ring 10 at the inner periphery and the inclined surface shape at the outer periphery. As described above, in order to lower the friction coefficient in the shape of the inclined surface of the outer peripheral portion, the inclination angle cannot be made too large, so that the force for pushing the ball 9 upward is not large. For this reason, there are cases where the ball 9 returns once it has risen along the inclined surface. In this state, the coefficient of friction is large,
When the ball 9 returns to the bottom surface, the ball 9 comes into contact with the guide ring 10 easily. When the ball 9 comes into contact with the guide ring 10, the ball 9 is moved in the rotating direction. .

As shown in FIG. 1, the ring groove 8 is formed by directly shaving the turntable 1 on the disk mounting surface side. This is different from the structure in which the ring groove 8 is formed on the side opposite to the disk mounting surface, because the ring groove 8 can be formed by the same chucking or the same mold as the guide of the disk center hole of the turntable 1. Rotational vibration of the outer peripheral portion of the disk drive 8 is reduced, and the dynamic balance of the disk drive device is reduced, so that vibration and noise can be reduced.

When the chassis 103 (see FIG. 2) vibrates, a relative rotational force to the turntable 1 acts on the ball 9 due to a shift between the center of rotation and the center of the turntable 1. When the displacement of the center of gravity of the recording disk is small, the main cause of the displacement of the center of gravity of the entire system is the ball 9 itself.
When a plurality of balls 9 are used, a kind of oscillation phenomenon that corrects the eccentricity of each other occurs. Therefore, the relative rotational movement of the ball 9 with respect to the turntable 1 does not stop even during high-speed rotation, which causes vibration and noise. This is a phenomenon that occurs because the frictional force and the damping force for the relative rotation of the ball 9 are too small.

As a countermeasure, in the present embodiment, the oscillation phenomenon is suppressed by applying a lubricant such as graphite, molybdenum disulfide, fluororesin, silicone oil or the like to the wall surface of the ring groove 8 or by injecting a liquid. In addition, the balance can be smoothly adjusted.

In the above-described embodiment, the turntable is provided with the ring groove. However, the present invention is not limited to this, and the ring groove may be provided on another rotating member that rotates about the shaft.

[0044]

According to the first aspect of the present invention, as described above, the provision of the catch on the inner peripheral side of the ring groove promotes the rotation of the ball even when the apparatus is placed vertically.
Balance correction can be performed even at relatively low speed rotation.

According to the second aspect of the present invention, as described above, the provision of the catch on the lid promotes the rotation of the ball even when the apparatus is placed vertically, and corrects the balance even at a relatively low speed. be able to.

According to the third aspect of the present invention, as described above, since the vibration damping means is provided inside the ring groove, the oscillation phenomenon of the ball in the ring groove is suppressed, and the balance is smoothly adjusted. be able to.

According to the fourth aspect of the present invention, as described above, by forming the outer peripheral portion of the ring groove into a conical surface shape, the ball floats from the groove bottom surface and rotates in a state close to a pure rolling motion. Is extremely small, the ball moves lightly, and the balance correction ability increases when used in combination with the guide ring.

According to the fifth aspect of the present invention, as described above, since the annular groove is formed on the outer peripheral portion of the ring groove, when the ball floats from the groove bottom surface and is caught by the annular groove, the ball is close to a pure rolling motion. , So the friction is extremely small,
The ball moves lightly and the balance correction ability increases.

According to the sixth aspect of the present invention, as described above, the hard layer is formed on the inner surface of the ring groove and the surface hardness is increased, so that the number of dents due to the ball is reduced and the coefficient of friction is reduced. Yes, the balance correction ability increases.

According to the seventh aspect of the present invention, as described above, since the ring groove is formed on the disk mounting surface side of the turntable, the same chucking or molding by the same mold as the guide portion of the disk center hole of the turntable is used. Is possible,
Rotational runout at the outer peripheral portion of the ring groove is reduced, and the dynamic balance of the disk drive device is reduced, so that vibration and noise can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a schematic configuration diagram showing a support structure of the disk drive device.

FIG. 3 is an enlarged sectional view of a ring groove of the disk drive device.

FIG. 4 is an enlarged sectional view of a ring groove of a disk drive according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a state where a guide ring is mounted in a ring groove according to the present invention.

FIG. 6 is a perspective view of a guide ring according to the present invention.

FIG. 7 is a perspective view of a lid according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turntable 2 Shaft 3 Bearing 4 Case 5 Stator 6 Rotor magnet 7 Metal case 8 Ring groove 9 Metal ball 10 Guide ring 11 Cover 12 Recording disk 13 Sheet 14 Cap 15 Projection 16 Ring groove 17 Projection

Continued on the front page (72) Inventor Akiyu Terada 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Hitachi Image Information System Co., Ltd.

Claims (21)

[Claims] 1. A disk drive in which a ring groove is provided around the center of rotation of a shaft, and a ball for dynamic balance correction is movably inserted into the ring groove. A disk drive device having a hook portion on which a balance correction ball is hooked. 2. The disk drive device according to claim 1, wherein said hook portion is formed by a projection. 3. The disk drive device according to claim 1, wherein said catching portion is formed with irregularities. 4. The disk drive according to claim 1, wherein the hook portion is formed of a member having a large coefficient of friction. 5. The disk drive according to claim 2, wherein the protrusion is provided on an outer peripheral portion of a guide ring fitted to an inner peripheral portion of the ring groove. 6. The disk drive according to claim 2, wherein the protrusion is provided directly on an inner peripheral portion of the ring groove. 7. The disk drive according to claim 3, wherein the irregularities are provided on an outer peripheral portion of a guide ring fitted to an inner peripheral portion of the ring groove. 8. The disk drive according to claim 3, wherein the irregularities are provided directly on an inner peripheral portion of the ring groove. 9. The disk drive according to claim 4, wherein the guide ring fitted to the inner peripheral portion of the ring groove is made of a member having a large coefficient of friction. 10. The disk drive according to claim 4, wherein an inner peripheral portion of said ring groove is formed of a member having a large friction coefficient. 11. A disk drive device comprising: a ring groove having a center of rotation of a shaft as a center, a ball for dynamic balance correction movably inserted into the ring groove, and a lid provided at an opening of the ring groove. A disk drive device, comprising: a catch portion on the side of the lid facing the dynamic balance correction ball, where the dynamic balance correction ball is caught. 12. The disk drive device according to claim 11, wherein said hook portion is constituted by a projection. 13. The disk drive device according to claim 11, wherein said hook portion is formed with unevenness. 14. The disk drive according to claim 11, wherein said hook portion is formed of a member having a large coefficient of friction. 15. A disk drive device in which a ring groove is provided around the center of rotation of a shaft, and a ball for dynamic balance correction is movably inserted into the ring groove, wherein the dynamic balance correction is provided inside the ring groove. A disk drive device provided with vibration damping means for damping vibration of a ball for use. 16. The disk drive according to claim 15, wherein said vibration damping means is a lubricant applied to a wall surface of said ring groove. 17. The disk drive device according to claim 15, wherein said vibration damping means is a liquid injected into said ring groove. 18. A disk drive device in which a ring groove is provided around the center of rotation of a shaft, and a ball for dynamic balance correction is movably inserted in the ring groove. A disk drive device characterized in that it has a conical surface shape that expands in a direction away from each other, and a guide ring is fitted to an inner peripheral portion of the ring groove. 19. A disk drive device in which a ring groove centering on a rotation center of a shaft is provided, and a ball for dynamic balance correction is movably inserted in the ring groove. A disk drive device, wherein an annular groove extending in a direction is formed. 20. A disk drive device in which a ring groove centering on the rotation center of a shaft is provided and a ball for dynamic balance correction is movably inserted in the ring groove, wherein a hard layer is formed on an inner surface of the ring groove. A disk drive characterized by being formed. 21. A disk drive device in which a ring groove centering on the rotation center of a shaft is provided and a ball for dynamic balance correction is movably inserted in the ring groove, wherein the ring groove is on the disk mounting surface side of the turntable. A disk drive device characterized by being formed in a disk drive.