JP2001327120A - Disk drive - Google Patents

Abstract

[PROBLEMS] To provide a disk drive capable of reducing RRO and ONRRO, and reducing mechanical resonance by reducing variations in bonding strength and the like. SOLUTION: As shown in FIG.
A plurality of projections 12 are provided on the outer peripheral surface of the ball bearing to divide the joint region with the inner peripheral surface of the ball bearing along the circumferential direction. FIG.
As shown in (b), a plurality of projections 13 are provided on the inner peripheral surface of the rotor hub 5a to divide the joint region with the outer peripheral surface of the ball bearing along the circumferential direction.

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 structure for mounting a ball bearing on a shaft or a rotor hub.

[0002]

2. Description of the Related Art Recording capacity is of the utmost importance as specifications and performance of a disk drive. As a high-density technology for recording more information within a limited standard size, a disk drive device is required to have improved rotational accuracy.

FIG. 14 shows a spindle motor 2f used in a conventional disk drive. The base end of the shaft 3d is press-fitted into the base 1 as the fixed side,
A rotor hub 5d is rotatably supported at the tip of the rotor d via a pair of ball bearings 4a and 4b.

The base 1 is provided with a stator 9 in which a stator coil 9b is wound around a stator core 9a. A magnet 7 is mounted on a surface of the rotor hub 5d facing the stator 9 via a yoke 8, and the stator coil 9b is fixed to the stator coil 9b. A rotating force is generated in the rotor hub 5 by the alternating magnetic field formed by the flowing current and the magnetic field of the magnet 7.

[0005] The ball bearings 4a, 4b are
And an inner ring 24 and a plurality of balls 25 interposed therebetween. A ring-shaped spacer bearing 19 is sandwiched between the opposed outer rings 23 of the pair of ball bearings 4a and 4b. In this state, the outer peripheral surfaces of the ball bearings 4a, 4b are fixed to the inner peripheral surface of the rotor hub 5d by light press-fitting together with an adhesive, and an axial load (hereinafter, referred to as "pressurization") is applied to the inner ring 24. In this state, the inner peripheral surface is fixed to the outer peripheral surface of the shaft 3d with an adhesive.

[0006] With such a configuration, the rotor hub 5d is rotatably supported by the shaft 3d with no backlash to the shaft 3d and with disturbance stiffness. Reference numeral 6 denotes a flange for mounting a disk formed on the outer peripheral surface of the rotor hub 5d. The magnetic seal 10 and the labyrinth seal 11 are provided in order to prevent the contamination generated in the internal space from scattering to the disk drive, and to reduce the adverse effect on the recording / reproducing operation between the head and the disk. Calibrated.

[0007]

In the spindle motor 2f configured as described above, the ball bearings 4a,
The rotor hub 5d attached via the support 4b is rotatably supported as described above.
a and 4b include repetitive run-out (hereinafter referred to as “RRO”) synchronized with the rotation of the rotor hub 5 and a non-rotational synchronous component (Non Re
petroleum run out (hereinafter referred to as "NRRO"), and there is a demand for an improved mounting structure of the ball bearings 4a and 4b to the shaft 3d and the rotor hub 5d.

[0008] Among such problems, for RRO, the tracking error can be kept relatively small by the learning control technique by the improvement of the control technique in recent years.
RRO remains a major problem as an obstacle to high density.

The NR of the ball bearings 4a and 4b will be described below.
The cause of RO occurrence will be described. The basic mechanism of NRRO generation is that the races of the inner ring 24 and the outer ring 23 and all balls 25
The rotational race moves to a position where the forces balance, due to the unbalance of the elastic contact forces acting between the rotating races.

The causes of NRRO in the ball bearings 4a and 4b can be roughly classified into the following three. The first occurrence factor is caused by a ridge of undulation caused by a shape error (inner / outer ring component) between the inner ring 24 and the outer ring 23, and occurs when the following equation is satisfied.

[0011] Here, Z is the number of balls 25, n is a natural number, and m is a natural number unrelated to n. The second factor is due to a dimensional error (ball cage component) of the ball 25, and the third factor is due to a shape error (ball component) of the ball 25.

FIG. 15 shows NRRO due to the first occurrence factor.
Indicates the occurrence of Here, the cause of the NRRO caused by the shape error of the outer ring 23 of the ball bearings 4a and 4b is shown.
The case where the outer ring 23 rotates counterclockwise [in the direction of arrow A], the ball 25 is used, and n = 1 and m = 1 will be described by taking the fixed shaft type spindle motor 2f as an example. . 23b is the center of rotation of the outer ring 23, 24b
Indicates the center of rotation of the inner ring 24.

[0015] As shown in FIG.
3 and the ball and the ball are in contact with the vicinity of the undulation peak of the outer ring 23, the ball and the ball near the position symmetrical with respect to the rotation center axis with respect to the ball are the outer ring 2
Touch the swell valley of 3. At this time, the sum of the elastic contact forces generated from the balls to all the balls 25 acts in the + direction of the Y-axis, and the rotating orbital ring (here, the outer ring 23) moves its rotation center 23b in the + direction of the Y-axis. It is.

At the next moment, as shown in FIG. 15B, the arrangement of the balls 25 and the undulation of the outer ring 23 are symmetrical with respect to the X axis, and the elasticity generated in all the balls 25 from one ball to another. The sum of the contact forces acts in the negative direction of the X axis, and the outer ring 23
Is rotated in the negative direction of the X-axis.

At the next moment, as shown in FIG. 15C, when the ball contacts the undulation peak of the outer ring 23, and the ball and the ball are in contact with the vicinity of the undulation peak of the outer ring 23, The ball and the ball near the symmetrical position with respect to the rotation center axis with respect to the ball contact the undulating valley of the outer ring 23. Then, the sum of the elastic contact forces generated from the balls to all the balls 25 acts in the negative direction of the Y axis, and the rotation center 23
b is moved in the negative direction of the Y axis.

In the case where the inner ring 24 has undulation, or in the case where the sum of the elastic contact forces acting on all the balls 25 does not become zero in a qualitative manner, it is qualitatively the same. , The rotating race is moved, which leads to the occurrence of NRRO.

.., M = 2, 3,..., Qualitatively, when the sum of the elastic contact forces acting on all the balls 25 does not become zero, The bearing ring is moved, which becomes NRRO. However, actually NR
What is observed as RO is due to low frequency undulations of up to about 10 peaks.

The above is the cause of the occurrence of NRRO. To reduce the NRRO of the ball bearings 4a and 4b, it is necessary to reduce the shape error and the dimensional error of the outer ring 23, the inner ring 24, and the balls 25, which are the components.

In the spindle motor 2f configured as described above, each component is fixed by means of bonding, press-fitting, shrink fitting, or the like. However, separation caused by vibration, impact, thermal deformation, or the like is performed. It needs to be mounted firmly to prevent destruction. On the other hand, the ball bearings 4a and 4b that rotatably support the rotor hub 5d with respect to the shaft 3d minimize damage such as deformation when attached to the spindle motor 2f in order to suppress the occurrence of NRRO as described above. It must be controlled and the conflicting conditions must be met.

Further, the RRO of the spindle motor 2f alone
Increases, the recording / reproducing operation will be hindered, such as the occurrence of vibration due to an increase in imbalance and a decrease in signal output due to fluctuations in the gap between the head and the disk caused by axial runout. It is required to perform high-precision assembly up to the position and posture to reduce RRO.

In consideration of the above, in order to reduce the NRRO and rotate the rotor hub 5 coaxially with the shaft 3, that is, to reduce the RRO, generally, the rotor hub 5 and the ball bearing 4 are fixed by light press-fitting. Means such as bonding with a clearance of about several microns, or light press-fitting using an adhesive are used. In order to fix the shaft 3d and the ball bearings 4a and 4b, an adhesive having a clearance of about several microns is used.

Next, after the disk is mounted on the spindle motor 2f configured as described above, N
An increase in RRO and an increase in RRO will be described. FIG.
Shows a configuration for mounting the disk 15 on the spindle motor 2f.

A disk 15 as a recording medium is mounted on the flange 6 so that the center hole of the disk 15 is engaged with the rotor hub 5, and a plurality of disks 1 are interposed via a spacer disk 16.
5 are arranged.

The periphery of the center hole of the disk 15 is pressed by a clamp disk 17 and fastened to the rotor hub 5 with screws 18 so as to be coaxially and integrally rotatable with the spindle motor 2f.

In the disk drive configured as described above, it is necessary to guarantee the operation in a temperature range of about 5 ° C. to 55 ° C. However, since the rotor hub 5d is generally made of aluminum, and the inner race 24, the outer race 23, and the ball 25 of the ball bearings 4a and 4b are made of stainless steel, when a temperature change occurs in the use environment of the disk device, the heat of the aluminum and stainless steel is increased. Due to the difference in expansion, stress is generated in the rotor hub 5d and the ball bearings 4a and 4b, and a phenomenon that is detrimental to high density is caused as described below.

First, when the deformation of the rotor hub 5d reaches the data track on the disk 15 due to the above-mentioned stress, R
When the RO increases, the recording / reproducing operation is hindered. When the outer ring 23 of the ball bearings 4a, 4b is deformed by this stress, the NRRO increases, and the recording / reproducing operation is hindered.

When the rotor hub 5d is made of stainless steel, the deformation due to the thermal stress as described above is relatively small, but the inner ring 24 and the outer ring 2
3. The ball 25 is deformed and NRRO may increase. Similarly, when the shaft 3d and the inner ring 24 are made of stainless steel having the same thermal expansion, the deformation due to the thermal stress is relatively small, but the inner ring 24, the outer ring 23, and the ball 25 are deformed by applying a preload. However, NRRO increases.

To solve such a problem, a spindle motor 2g configured as shown in FIG. 17 has been proposed. In the spindle motor 2g, the fixing structure of the rotor hub 5d and the outer ring 23 is improved by using the cartridge bearing 14c having a small number of parts.
That is, focusing on the stress generated in the contact area between the rotor hub 5d and the outer ring 23, the joining area 26c between the rotor hub 5d and the outer ring 23 is a section sandwiched between the holding portions of the balls 25 of the cartridge bearing 14c.

According to this structure, even if the outer ring 23 is deformed due to the attachment of the cartridge bearing 14c and the rotor hub 5d or a change in temperature, the deformation at the contact portion with the ball 25 is alleviated.
We can expect a decrease.

Further, since the number of components is small, dimensional errors and deviations in posture during assembly are reduced, and RRO can be reduced. As described above, in order to advance the technology corresponding to the high density of the disk drive, the ball bearings 4a, 4
b, reducing the NRRO at the time of assembling the ball bearings 4a, 4b to the spindle motor 2 and increasing the NRRO at the time of light press-fitting, preventing the RRO / NRRO from increasing by applying a pressurized force, NR due to thermal stress after assembly of motor 2
It has been clarified that it is necessary to take measures to prevent an increase in RO and to prevent an increase in RRO due to thermal stress after the disk 15 is attached.

FIG. 18 shows the shaft 3d of the spindle motor 2f and the inner race 24 of the ball bearings 4a and 4b.
This shows the state of adhesion to FIGS. 18A and 18B show a state in which the inner ring 24 and the shaft 3d having the same dimensional / shape error are bonded with the adhesive 20. FIG. Reference numeral 30 denotes an unbonded area of the adhesive.

As described above, it is apparent that even if the relative mounting positions and angles of the two are different, a difference occurs in the bonding area. Further, when the size and shape vary within a predetermined range, a further difference occurs in the bonding area.

Although the adhesive 20 is applied only to the inner peripheral surface of the inner ring 24 here, the same phenomenon occurs when the curing accelerator is applied to the outer peripheral portion of the shaft 3d.
In addition to the adhesion between the shaft 3d and the inner ring 24 of the ball bearings 4a, 4b, the ball bearings 4a, 4b
Even in the case of light press-fitting between the outer peripheral portion of b and the inner peripheral surface of the rotor hub 5d, the same fixing force cannot be obtained at all positions in the joining region as described above. For example, since errors such as delicate dimensions, surface roughness, and undulations are present, variations occur in the bonding area, bonding position, and bonding force in the bonding region, and the natural frequency of the spindle motor 2f varies.
Natural vibration of other components and ball bearings 4a, 4b
May resonate with the NRRO vibration.

FIG. 19 shows the mounting state of the ball bearings 4a and 4b in the spindle motor 2f. FIG.
FIG. 8B is an enlarged view of a region C in FIG. When the ball bearings 4a, 4b are inserted between the rotor hub 5d and the shaft 3d, the spacer bearings 19
The contact surfaces of the ball bearings 4a and 4b with the outer ring 23 have slight errors such as inclination, surface roughness, and undulation. Therefore, the mounting positions and postures of the ball bearings 4a and 4b are spacer bearings. A deviation larger than the value specified for the degree of parallelism and surface roughness of the contact surface with the outer ring 23 occurs.

Therefore, not only increase in RRO, but also fixing, application of pressurization, and generation of thermal stress while the mounting position and posture are shifted, the components of the ball bearings 4a and 4b are deformed irregularly, resulting in NRRO. Cause an increase.

FIG. 20 shows the application of a preload to the spindle motor 2f. The ball bearings 4a and 4b have
A load is applied by a pressurizing weight or a pressurizing jig 21 as shown by an arrow B.

At this time, since errors such as slight inclination, surface roughness, and undulation exist on the upper surface of the pressurizing weight, the pressurizing jig 21 or the inner ring 24, the pressurizing is uniform over the entire circumference of the inner ring 24. And the NRRO and RRO may increase due to deviations in the mounting positions and postures of the ball bearings 4a and 4b, and irregular deformation of the inner ring 24.

It goes without saying that when the above-mentioned thermal stress is applied to such a state, RRO and NRRO further increase. As a method of coping with such RRO and NRRO in discrete type ball bearings 4a and 4b, efforts are being made to increase the processing accuracy of the inner ring 24, outer ring 23 and balls 25 of the ball bearings 4a and 4b. However, an improvement in processing accuracy necessarily leads to an increase in cost, and goes against the cost reduction of the disk drive.

Further, at the time of incorporation into a disk drive, a portion engaged with and fixed to the ball bearings 4a and 4b;
That is, a method of improving the processing accuracy of the outer peripheral surface of the shaft 3a and the inner peripheral surface of the rotor hub 5d to reduce RRO,
Similarly, a method of improving the processing accuracy to reduce variations in the bonding area, the bonding position, and the bonding force in the bonding region generated during bonding or light press-fitting can be considered, but this also leads to an increase in cost.

Further, in the spindle motor 2g of the disk drive device configured as shown in FIG. 17, even if the outer ring 23 is deformed due to the mounting of the cartridge bearing 14 and the rotor hub 5d or a change in temperature, the contact portion with the ball 25 is formed. Since the deformation is alleviated, NRRO can be expected to be somewhat reduced as compared with other conventional examples. In addition, since the number of parts is small, dimensional errors and deviations in posture during assembly are reduced,
RRO can also be reduced.

However, as important design guidelines for the spindle motors 2f and 2g as disk drive devices, avoidance of natural vibration of the spindle motors 2f and 2g at the rated rotation speed and resonance with NRRO are mentioned.

Of these frequencies, the NRRO frequency can be obtained with high accuracy by calculation, but the natural frequency can be determined in detail by examining the strength of the joint fixing portion during assembly and the effects of centrifugal force during rotation. It is difficult to reflect on the calculation result, and the calculation prediction and the actual measurement may be different. Therefore, in order to prevent the excitation of resonance that actually hinders the recording / reproducing operation, the design must be performed in consideration of the frequency up to about 2 kHz.

However, since there are a large number of natural vibrations and NRROs of the spindle motor in this range, not only the prediction by calculation but also the design specifications of the spindle motor do not become firm unless actual trial evaluation is performed.

The method of avoiding the resonance of the NRRO with the natural vibration of the spindle motor is generally the simplest and most reliable method in consideration of the shortening of the response time and cost. And the rigidity of the spindle motor is changed by changing the position of the support of the ball bearing with respect to the rotational center of gravity.

FIG. 21 shows how the ball bearings 4a, 4b are mounted on the spindle motors 2f, 2g.
N due to change of internal specifications of ball bearings 4a, 4b
Changes in RRO and changes in stiffness are considered to be avoided as much as possible in consideration of the time required for the response, the cost, the burden on other performance due to the change, and the risk of unexpected failures.

As shown in FIG. 21 (a), when a discrete bearing is used, the distance L between the ball bearings 4a and 4b, which is a general method described above, is changed, and the ball is positioned with respect to the center of gravity of the rotating body. Bearings 4a, 4b
The rigidity of the spindle motor 2f can be easily changed only by changing the dimensions of the spacer bearing 19 and the rotor hub 5 by changing the position of the support portion.

On the other hand, when the cartridge bearing 14c shown in FIG. 17 is used, a part of the rotor hub 5d and a part of the ball bearings 4a, 4b are integrally formed.
Although the manufacturing cost can be reduced and the shaft runout accuracy of the spindle motor 2g can be improved, the positions of the inner raceway 28 and the outer raceway 29 of the cartridge bearing 14c as shown in FIG. It is necessary to change both the specifications inside the bearing and the like and the rotor hub 5d. In addition, there is a problem that routing is inconvenient at the time of mass production design of the spindle motor 2g. The spindle motor 2g is used only for a part of currently manufactured spindle motors, and most of them use discrete type ball bearings 4a and 4b. ing.

As described above, the spindle motor 2g can be applied only when the cartridge bearing 14c is used, and can be applied to the discrete type ball bearings 4a and 4g.
An effective configuration and means for reducing NRRO and RRO when using b is required.

The present invention solves the above-mentioned problem, and fixes the spindle motor to a ball bearing, applies a pressurization, and causes thermal stress after assembling the spindle motor.
It is an object of the present invention to provide a disk drive capable of reducing RO and NRRO, and further reducing variations in bonding strength and the like to reduce problems related to mechanical resonance.

[0050]

According to the present invention, there is provided a disk drive device comprising: a joining region between an outer peripheral surface of a shaft and an inner peripheral surface of a ball bearing; or a joining region of an inner peripheral surface of a rotor hub 5 and an outer peripheral surface of a ball bearing 4. The region is divided into a plurality of regions along the circumferential direction.

According to the present invention, the RRO and NRRO can be reduced, and the variation in the joining force in the joining region can be reduced. Can be realized.

[0052]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a disk drive according to a first aspect of the present invention, a ball bearing is provided between an outer periphery of a shaft and an inner periphery of a rotor hub to rotatably support the rotor hub with respect to the shaft. The joint region between the outer peripheral surface of the shaft and the inner peripheral surface of the ball bearing is divided into a plurality of regions along the circumferential direction.

According to this configuration, when the outer peripheral surface of the shaft and the inner peripheral surface of the ball bearing are bonded or lightly press-fitted, even if errors such as delicate dimensions, surface roughness, undulation, etc. exist between them, the bonding area and the bonding can be improved. By reducing the variation in the position and the joining force, a reduction in rigidity of the spindle motor and a resonance phenomenon between the spindle motor and other components and the ball bearing NRRO can be reduced, and a spindle motor of stable quality can be realized.

According to a second aspect of the present invention, in the disk drive device, a ball bearing is provided between the outer periphery of the shaft and the inner periphery of the rotor hub to rotatably support the rotor hub with respect to the shaft. The joint area between the peripheral surface and the outer peripheral surface of the ball bearing is divided into a plurality of areas along the circumferential direction.

According to this configuration, when the inner peripheral surface of the rotor hub and the outer peripheral surface of the ball bearing are bonded or lightly press-fitted to each other, even if errors such as delicate dimensions, surface roughness, and undulation exist between the two, the joining area can be increased. By reducing the variation in the joining position and joining force, the rigidity of the spindle motor can be reduced, and the resonance phenomenon between the spindle motor and other components and the ball bearing NRRO can be reduced. Even when the deformation extends to the data track of the disk, the order of the undulation is the same as the number divided into the plurality of regions, so that the learning control for a specific frequency is set strongly, so that the recording and reproducing operation can be performed. It is possible to provide a spindle motor having a stable quality without any adverse effect.

According to a third aspect of the present invention, there is provided a disk drive device according to the first aspect, wherein a plurality of projections are provided on an outer peripheral surface of the shaft to divide the joining region into a plurality of regions.

According to a fourth aspect of the present invention, there is provided a disk drive device according to the first aspect, wherein a plurality of recesses are provided on an outer peripheral surface of the shaft to divide the joining region into a plurality of regions.

According to a fifth aspect of the present invention, in the second aspect, a plurality of projections are provided on an inner peripheral surface of the rotor hub to divide the joining region into a plurality of regions. .

According to a sixth aspect of the present invention, in the second aspect, a plurality of recesses are provided on an inner peripheral surface of the rotor hub to divide the joining region into a plurality of regions.

According to a seventh aspect of the present invention, in the disk drive device according to the first or second aspect, the divided joining regions are uniformly arranged on the entire circumference of the shaft, and the divided number is Z Where n is a natural number and n is a natural number.

According to this configuration, even if the components of the ball bearing are deformed at the time of bonding or light press-fitting, the unbalance of the elastic contact forces acting between the inner and outer races and all the balls can be reduced. A spindle motor with a small NRRO can be realized.

The disk drive according to claim 8 of the present invention is the disk drive according to claim 1 or 2, wherein the divided joining areas are uniformly arranged on the entire circumference of the shaft, and the number of divisions is Z Where n is a natural number and the product of Z and n is (Z × n).

According to this configuration, even if the ball bearing components such as the inner ring, the outer ring and the rolling elements are deformed at the time of bonding or light press-fitting, the elastic contact acting between the inner / outer ring races and all the balls. Can reduce power imbalance,
A spindle motor with a small NRRO can be realized.

According to a ninth aspect of the present invention, a pair of ball bearings is provided between an outer periphery of a shaft and an inner periphery of a rotor hub, with a ring-shaped spacer bearing interposed between opposed outer rings. A disk drive that rotatably supports the rotor hub with respect to the shaft and applies an axial load to the inner ring side of the pair of ball bearings, the outer ring of the pair of ball bearings and the spacer bearing. A plurality of contact points are provided along the circumferential direction, respectively.

According to this configuration, when the ball bearing is inserted into the rotor hub or the shaft, even if there are slight errors such as slight inclination, surface roughness, and undulation of the side surface of the spacer bearing, the mounting position of the ball bearing can be improved. It is possible to realize a spindle motor of stable quality with small NRRO and RRO by eliminating deviations in posture and posture.

According to a tenth aspect of the present invention, in the ninth aspect, a contact point between the outer ring of the ball bearing and the spacer bearing is provided at equal intervals over the entire circumference of the ball bearing. Is a natural number represented by Z / n when n is a natural number.

According to this configuration, even if the ball bearing components, especially the outer ring, are deformed when the ball bearing is assembled to the spindle motor or when thermal stress is generated,
It is possible to reduce the unbalance of the elastic contact forces acting between the inner and outer races and all the balls, and to provide a spindle motor with a small NRRO.

According to an eleventh aspect of the present invention, in the ninth aspect, the contact point between the outer race of the ball bearing and the spacer bearing is provided at equal intervals over the entire circumference of the ball bearing. Is the number of balls of a ball bearing and n is a natural number, and is the product of Z and n (Z × n).

According to this configuration, even if the ball bearing components, especially the outer ring, are deformed when the ball bearing is assembled to the spindle motor or when thermal stress is generated, the ball bearing acts between the inner and outer ring races and all the balls. An unbalance in elastic contact force can be reduced, and a spindle motor with a small NRRO can be realized.

In a twelfth aspect of the present invention, in the ninth aspect, the outer ring of the pair of ball bearings and the spacer bearing are joined and fixed at a plurality of positions.

According to this structure, even when the components of the ball bearing, particularly the outer ring, are deformed when the pair of ball bearings generates thermal stress, the elastic contact acting between the inner and outer races and all the balls is obtained. A power imbalance can be reduced, and a spindle motor with a small NRRO can be realized.

According to a thirteenth aspect of the present invention, in the twelfth aspect, a plurality of protrusions are provided on a surface of the spacer bearing facing the ball bearing, and are bonded.

A disk drive according to a fourteenth aspect of the present invention is the disk drive according to the twelfth aspect, wherein a plurality of recesses are provided on a surface of the spacer bearing facing the ball bearing and are bonded.

A disk drive according to a fifteenth aspect of the present invention is characterized in that, in the ninth aspect, the axial load applied to the inner ring of the ball bearing is distributed to at least two or more locations in the circumferential direction.

According to this configuration, even if there is an error such as a slight inclination, surface roughness, or undulation of the pressurized weight or pressurizing jig or the inner ring side surface, the pressurized pressure is distributed over the entire circumference of the inner ring. The displacement of the mounting position and posture of the ball bearing is small, the irregular deformation of the inner ring can be reduced, and a spindle motor with small RRO and NRRO can be realized.

According to a ninth aspect of the present invention, in the ninth aspect of the present invention, in the ninth aspect, the axial load applied to the inner race of the ball bearing is represented by Z being the number of balls of the ball bearing and n being a natural number along the circumferential direction. And then distributed to natural numbers represented by Z / n.

According to this configuration, it is possible to reduce the deformation of the ball bearing components, particularly the inner ring, when the preload is applied, and to act between the inner and outer ring races and all the balls even if the deformation occurs. Therefore, it is possible to reduce the unbalance of the elastic contact force, thereby realizing a spindle motor having a small RRO or NRRO.

According to a ninth aspect of the present invention, in the ninth aspect, in the ninth aspect, the axial load applied to the inner race of the ball bearing is represented by Z being the number of balls of the ball bearing and n being a natural number along the circumferential direction. And then distributed to the location represented by the product of Z and n (Z × n).

According to this configuration, it is possible to reduce the irregular deformation of the ball bearing components, particularly the inner ring, at the time of applying a pressurization, and even if the deformation occurs, it acts between the inner and outer ring races and all the balls. Therefore, it is possible to reduce the unbalance of the elastic contact force, thereby realizing a spindle motor having a small RRO or NRRO.

The disk drive according to claim 18 of the present invention is characterized in that in any of claims 9 to 17, the spacer bearing is formed integrally with the rotor hub.

According to a nineteenth aspect of the present invention, there is provided a disk drive according to the fifteenth to seventeenth aspects, wherein the pair of ball bearings has outer ring surfaces opposed to each other and a ring-shaped spacer bearing sandwiched therebetween. Are integrally formed as a cartridge bearing.

According to a twentieth aspect of the present invention, in the disk drive device according to the ninth to seventeenth aspects, the opposed outer races of the pair of ball bearings, and the spacer bearing and the rotor hub interposed therebetween. Are integrally formed as a cartridge bearing.

According to a twenty-first aspect of the present invention, in the disk drive device according to the first to twentieth aspects, the rotor hub is a fixed base. According to this configuration, the present invention is also applicable to a shaft rotation type spindle motor. The same effect can be obtained in each case.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 13. (Embodiment 1) FIGS. 1 to 3 show (Embodiment 1) of the present invention.

In this (Embodiment 1), in order to reduce PRO and NRRO, a plurality of projections 12 are provided on the outer peripheral surface of the shaft 3a, and a plurality of projections 13 are provided on the inner peripheral surface of the rotor hub 5a. Therefore, the joint region between the shaft 3a and the ball bearings 4a and 4b and the joint region between the rotor hub 5a and the ball bearings 4a and 4b are divided into a plurality of regions.

More specifically, as shown in FIG. 1A, a plurality of protrusions 12 extending along the axial direction are formed on the outer peripheral surface of the shaft 3a at equal intervals in the circumferential direction. As shown in b), a plurality of projections 13 extending along the axial direction are formed at equal intervals in the circumferential direction on the inner peripheral surface of the rotor hub 5a.

As shown in FIG. 2, the spindle motor 2a
Is a pair of ball bearings 4 between the outer peripheral surface of the shaft 3a and the inner peripheral surface of the rotor hub 5a.
a, 4b are interposed. In addition, ball bearing 4
The inner ring 24 of a and 4b is configured to apply an axial load.

Since the protruding portions 12 and 13 are formed on the shaft 3a and the rotor hub 5a as described above, the outer peripheral surface of the shaft 3a and the ball bearing 4 are formed as shown in FIG.
The joining area 26a of the inner ring 24a with the inner ring 24 is divided into a plurality of areas along the circumferential direction, and a gap 27a is arranged between the joining areas 26a. Further, a joining region 26 between the inner peripheral surface of the rotor hub 5a and the outer peripheral surfaces of the ball bearings 4a, 4b.
b is also divided into a plurality of regions along the circumferential direction by the protrusions 13 formed on the inner peripheral surface of the rotor hub 5a, and a gap 27b is formed between the joining regions 26a.

As described above, the shaft 3a and the ball bearing 4 or the rotor hub 5a and the ball bearings 4a and 4b
By dividing the joining regions 26a and 26b with a limited region in advance by dividing into a plurality of regions, the joining regions 26a and 26b
Even if there are slight errors such as dimensional differences, surface roughness, waviness, etc. on the contact surface of the contact surface 26b, this variation is only in the limited joining regions 26a, 26b, so that the joining force varies. Can be reduced.

As a result, it is possible to reduce the reduction and variation in the rigidity of the spindle motor 2a, and to reduce the resonance phenomenon of other components and the ball bearings 4a and 4b with the NRRO.
A spindle motor 2a of stable quality can be provided.

Even if a thermal stress occurs such that the deformation of the rotor hub 5a extends over the data track of the disk 15 due to the difference in the thermal expansion coefficient between the ball bearings 4a, 4b and the rotor hub 5a, the undulation caused by the thermal stress is as described above. As described above, since the same number as the number of divided joining regions 26b of the rotor hub 5a becomes dominant, it is possible to cope with setting strongly the learning control for a specific frequency.

That is, the rotational speed of the spindle motor 2 is represented by f
[Hz], and the number of protrusions 13 provided on the rotor hub 5a is i, the frequency of the generated undulation is f × i [Hz]. Since this swing is synchronized with the rotation, that is, RRO, an efficient control of setting a strong response to this frequency when setting the learning control and weakening the response to the unnecessary rotation synchronization frequency is performed. And a stable quality spindle motor 2a that does not adversely affect the recording / reproducing operation can be provided.

In the above description, a plurality of projections 12 are formed on the outer peripheral surface of the shaft 3a to form the ball bearings 4a,
The joint region 26a with the shaft 4b is divided into a plurality of regions, but a concave portion is formed on the outer peripheral surface of the shaft 3a to form the joint region 26a.
a may be configured to be divided into a plurality of regions. Similarly, in the rotor hub 5a, a concave portion is provided instead of the convex portion 13 so that the joint region 26b with the ball bearings 4a and 4b is formed.
May be divided into a plurality of regions.

The outer peripheral portion of the shaft 3a and the inner peripheral surface of the rotor hub 5a may be subjected to a mechanical or chemical surface treatment or a film forming treatment instead of the convex portions 12, 13 or the concave portions.

In the above description, the bonding regions 26a, 26a
Although 6b is divided into two, the number of the joining regions 26a and 26b may be plural, and the number is not particularly limited. Further, in FIGS. 1A and 1B, the protrusions 12, 1
The height of the joining regions 26a, 2 is increased depending on the use environment, particularly the use temperature condition, although the height of the joint regions 26a, 2 is large.
As long as the gap 6b and the gaps 27a, 27b are formed, the order may be on the order of μm. This is the same for the concave portion.

In the above description, the protruding portions 12, 13 are formed on both the outer peripheral surface of the shaft 3a and the inner peripheral surface of the rotor hub 5a. (Embodiment 2) FIG. 4 shows (Embodiment 2) of the present invention.

In this (Embodiment 2), the rotor hub 5
The difference is that the same number of the protrusions 13 formed on the inner peripheral surface of the ball bearing a as the number of the balls 25 of the ball bearing 4 are provided, but the other configuration is the same as the above (Embodiment 1).

More specifically, as shown in FIG. 4A, the same number of balls 25 as the number of balls 25 of the ball bearings 4a and 4b are provided on the inner peripheral surface of the rotor hub 5a constituting the spindle motor 2a.
The plurality of protrusions 13 are formed.

Hereinafter, the rotational drive of the ball bearings 4a, 4b and the rotor hub 5a will be described by taking as an example a case where the outer ring 23 of the ball bearings 4a, 4b has undulation. Note that, for the sake of explanation, the balls 25 are given the numbers 〜 to 玉 25, and the hills of the outer ring 23 are also assigned the numbers を. 23a is the center of the outer ring 23, 24
a indicates the center of the inner race 24, 29 indicates the outer raceway, and 28 indicates the inner raceway.

In FIG. 4 (a), the ball contacts the undulation peak of the outer ring, and the ball located at a position symmetrical with respect to the center axis of rotation contacts the undulation peak of the outer ring, and the trajectory of the ball and the outer ring The elastic contact force acting between the ball and the ball and the raceway 29 of the outer ring are balanced. Similarly, the elastic contact force acting between the ball and the outer raceway 29 and the elastic contact force acting between the ball and the outer raceway 29 are also balanced. The sum of the elastic contact forces generated in all the balls is balanced.

Therefore, the rotating race (the outer race 23 in this case)
NRRO does not occur. Further, even when the rotor hub 5a rotates in the direction of arrow A to the state shown in FIG.
Are in a balanced state, and NRRO is not generated.

In this configuration, the same number of protrusions 13 as the number of balls are formed on the inner peripheral surface of the rotor hub 5a, and the joining region 26b between the inner peripheral surface of the rotor hub 5a and the outer peripheral surface of the ball bearing 4 is uniformly divided. This is because errors such as undulations of the projections 23 are limited to the joining region 26b between the convex portion 13 and the outer peripheral surface of the ball bearing 4. The variation in joining force is reduced, and the rotor hub 5a rotates in the direction of arrow A. Even in the state shown in FIG. 4 (c), NRRO does not occur in the same manner as described above.

Therefore, when the ball bearings 4a and 4b are adhered to the spindle motor 2 or lightly pressed into the spindle motor 2, the unbalance of the elastic contact force acting between the inner and outer races and all the balls 25 due to thermal stress is reduced. NRRO due to the deformation of the inner ring 24 and the outer ring 23 can be reduced.
The spindle motor 2 with a small RRO can be realized.

In the above description, the example in which the convex portion 13 is formed on the inner peripheral surface of the rotor hub 5a has been described. However, a concave portion may be provided instead of the convex portion 13; Represents the number of balls 4c of the ball bearings 4a and 4b as Z,
When a natural number is n, a multiplier of Z and n (Z × n) or a divisor of Z and n (Z / n) may be used. Note that Z
For / n, it is necessary to select Z and n so that the value is a natural number.

In the above description, the case where the outer ring 23 has undulation is shown. However, the case where the convex portion 12 or the concave portion is provided on the outer peripheral surface of the shaft 3a can be similarly considered with respect to the undulation of the inner ring 24. It is sufficient that the occurrence of NRRO can be reduced, and the numbers of the convex portions 12 and the concave portions can be represented by Z / n or Z × n as described above.

(Embodiment 3) FIG. 5 shows (Embodiment 3) of the present invention. In this (Embodiment 3), a plurality of protrusions 2 are provided on the surface of spacer bearing 19 facing outer ring 23.
2 is provided, but the other configuration is the same as the above-described conventional example.

As shown in FIG. 5A, a plurality of convex portions 22 are formed on the surface of the spacer bearing 19 facing the outer ring 23 of the ball bearings 4a and 4b.
Is divided into three regions at equal intervals along the circumferential direction.

In the spindle motor 2 using the spacer bearing 19, as shown in FIG. 5B, the joint between the spacer ring 19 and the ball bearings 4a and 4b is divided into three regions in the circumferential direction. In addition, the projection 22 of the spacer bearing 19 and the outer ring 23 of the ball bearings 4a and 4b are reliably connected along the projection 22. Ball bearing 4 of projection 22
Since the contact surfaces with a and 4b indicate the parallelism and flatness of the spacer bearing 19, if the connection is reliably made along this contact surface as described above, the parallelism of the spacer bearing 19 can be improved. And the deviation of the mounting position and posture that exceed the values specified for the flatness are reduced.

Therefore, even if there are slight errors such as inclination, surface roughness, and undulation on the surface of the spacer bearing 19 facing the ball bearings 4a and 4b, the RRO can be reduced.
In addition, a stable quality spindle motor 2b that can reduce the displacement of the mounting positions and postures of the ball bearings 4a and 4b, does not increase the NRRO due to the irregular deformation of the ball bearings 4a and 4b due to the application of pressurization and thermal stress. realizable.

In the above description, the example in which the convex portion 22 is formed on the spacer bearing 19 has been described. However, a concave portion is formed instead of the convex portion 22 to join the spacer bearing 19 and the ball bearings 4a and 4b. The region may be divided evenly along the circumferential direction.

In the above description, the height of the convex portion 22 is set large for ease of description. However, the height of the convex portion 22 may be different from the bonding region and the gap under the use environment, particularly the use temperature condition. It may be on the order of μm as long as it is possible. This is the same for the concave portion.

In the above description, the joining region between the spacer bearing 19 and the ball bearings 4a and 4b is divided into three regions.
There is no particular limitation as long as the parallelism or flatness of the plane defined by 2 or the concave portion does not exceed a specified value.

(Embodiment 4) FIG. 6 shows (Embodiment 4) of the present invention. This (Embodiment 4) is different in that the number of protrusions 22 formed on the spacer bearing 19 is the same as the number of the balls 25, but the other configuration is the same as that of the above (Embodiment 3).

As shown in FIG. 6A, the spacer bearing 19 is formed with eight projections 22 equal in number to the balls 25 of the ball bearings 4a and 4b. FIG. 6 (b)
Shows a spindle motor 2c using the spacer bearing 19.

When a preload is applied to the inner rings 24 of the ball bearings 4a and 4b as shown by the arrow B, the load becomes
The light is transmitted from the inner ring 24 of the ball bearing 4 a to the ball 25 and then to the outer ring 23. Further, the component is transmitted to the spacer bearing 19 and then to the outer ring 23, the ball 25, and the inner ring 24 of the ball bearing 4b, and each component undergoes minute deformation.

At this time, the joining regions between the spacer bearings 19 and the outer races 23 of the ball bearings 4a and 4b are provided at equal intervals in the circumferential direction, and the number thereof is the same as the number of balls of the ball bearing 19 at eight places. Therefore, all the balls 25 are made according to the same principle as the above (Embodiment 2).
Are balanced, and no force is applied to the rotating race (here, the outer race 23).

Therefore, even if the components of the ball bearings 4a, 4b, particularly the outer ring 23, are deformed when the ball bearings 4a, 4b are attached to the spindle motor 2 when pressurization or thermal stress is generated, the inner and outer ring raceways are deformed. NR is reduced by reducing the unbalance of the elastic contact force acting between the wheel and all the balls.
The increase in RO can be greatly reduced, and the spindle motor 2c with small NRRO can be realized.

In the above description, the ball bearing 4
Although the case where the number of the balls 25 of a and 4b is eight has been described, the occurrence of NRRO can be reduced when the number of the balls 25 is other. Further, in the above description, the convex portion 22 is formed on the surface of the spacer bearing 19 facing the ball bearings 4a and 4b, but a concave portion may be formed instead of the convex portion 22.
Alternatively, when the number of balls 4c of the ball bearings 4a and 4b is Z and the natural number is n, the number of concave portions is a multiplier of Z and n (Z
× n) or the divisor of Z and n (Z / n). As for Z / n, Z and n are selected so that the value becomes a natural number.

(Embodiment 5) FIG. 7 shows (Embodiment 5) of the present invention. This (Embodiment 5) differs in that the outer races 23 of the ball bearings 4a and 4b and the projection 22 of the spacer bearing 19 are fixed with an adhesive 20, but other configurations are the same as those of the above (Embodiment 3). ) Is the same.

As shown in FIG. 7 (a), in the spacer bearing 19 constructed in the same manner as in FIG. 5 (a), an adhesive 20 is applied to the contact surface of the projection 22 with the ball bearings 4a, 4b. Have been.

Therefore, as shown in FIG. 7B, the spindle motor 2 using this spacer bearing 19
The convex portion 22 and the outer ring 23 of the ball bearings 4a and 4b are securely joined and fixed, and the frictional force in the joining region can be made uniform.

Further, since the projections 22 are arranged at equal intervals along the circumferential direction, the ball bearing 4
Even if a force is applied to the a and 4b, the biased deformation of the components of the ball bearings 4a and 4b caused by thermal stress, in particular, the unbalanced deformation of the outer ring 23 can be evenly distributed to the three fixed joints. To reduce the unbalanced deformation that occurs in
The spindle motor 2 having a small RRO can be realized. Furthermore, even if the components of the ball bearings 4a and 4b, particularly the outer race 23, are deformed by thermal stress, the inner and outer races 2
It is possible to reduce the unbalance of the elastic contact forces acting between 8, 29 and all the balls 25, and to realize the spindle motor 2b with a small NRRO.

In the above description, a plurality of projections 22 are formed on the surface of the spacer bearing 19 facing the ball bearings 4a and 4b, so that the joint region with the spacer bearing 19 is divided into a plurality of regions. Alternatively, a concave portion may be provided instead of the convex portion 22.

Further, on the surface of the spacer bearing 19 facing the ball bearings 4a, 4ba, 4b, a mechanical or chemical surface treatment or a film forming treatment may be applied instead of the convex portion 13 or the concave portion.

Further, in the above description, the joining region is divided into three, but the number is not particularly limited as long as there are a plurality of joining regions. (Embodiment 6) FIG. 8 shows (Embodiment 6) of the present invention.

In (Embodiment 6), a state in which a pressure is applied to the ball bearings 4a and 4b of the spindle motor 2b configured in the same manner as in (Embodiment 3) will be described. As shown by arrow B, ball bearings 4a, 4b
Applied to the inner ring 24 of the spacer bearing 1
In this case, three parts are provided in the circumferential direction, the number being equal to the number of joint regions between the ball bearings 9 and the ball bearings 4a and 4b.

As described above, by applying the pressurization uniformly distributed in the circumferential direction, errors such as slight inclination, surface roughness, undulation, etc., on the surface of the pressurizing weight, the pressurizing jig, the inner ring 24 or the like are reduced. Even if it is present, the preload can be distributed over the entire circumference of the inner ring 24 and applied, the deviation of the mounting positions and postures of the ball bearings 4a and 4b is small, and the irregular deformation of the inner ring 24 can be reduced. And a spindle motor 2b having a small NRRO.

In the above description, the pressurization is distributed and applied to three places. However, the present invention is not limited to this, and it is sufficient that a plurality of pressurizations are uniformly distributed in the circumferential direction. (Embodiment 7) FIG. 9 shows (Embodiment 7) of the present invention.

In this (Embodiment 7), an applied state of pressurizing the ball bearing 4 of the spindle motor 2c configured in the same manner as (Embodiment 4) will be described. As shown by the arrow B, the inner race 2 of the ball bearings 4a, 4b
When the pressurizing force applied to the inner ring 2 is divided into eight equal to the number of joint regions between the spacer bearing 19 and the ball bearings 4a and 4b, here the number of balls, the inner ring 2 is pressurized.
The deformation of 4 is the same as the number of balls of the ball bearings 4a and 4b.
Since the peak component is dominant, the sum of the elastic contact forces generated in all the balls 25 is in a balanced state as in the above (Embodiment 2), and the sum of the elastic contact forces with respect to the rotating race ring (here, the outer ring) is increased. Will not give power.

Therefore, even if a pressure is applied to the inner race 24 of the ball bearings 4a, 4b in the direction of arrow B when the ball bearings 4a, 4b are assembled to the spindle motor 2, the ball bearings 4a, 4b
Deviation of the mounting position and posture of the inner ring 24 is reduced.
Irregular deformation can be reduced. Even if the ball bearings 4a, 4b are deformed, the inner and outer races 28, 2
Unbalance in the elastic contact force acting between the ball 9 and all the balls 25 can be reduced, and the spindle motor 2c with a small RRO or NRRO can be realized.

In the above description, the ball bearing 4
Although the same number of protrusions 22 as the number of balls 25 of a and 4b are formed on the surface of the spacer bearing 19 facing the ball bearings 4a and 4b, the present invention is not limited to this.
The number of the convex portions 22 or the concave portions is determined by the ball bearings 4a, 4
When the number of balls 4c of b is Z and the natural number is n, a multiplier of Z and n (Z × n) or a divisor of Z and n (Z / n) may be used. As for Z / n, Z and n are selected so that the value becomes a natural number.

(Embodiment 8) FIG. 10 shows (Embodiment 8) of the present invention. In the above (Embodiment 3) to (Embodiment 7), the spacer bearing 19 and the rotor hub 5
a are provided individually, but in order to reduce the number of parts, etc., as shown in FIG.
The effect similar to the above can be obtained by d.

(Embodiment 9) FIG. 11 shows (Embodiment 9) of the present invention. In the spindle motor 2b configured in the same manner as in the above (Embodiment 6) and (Embodiment 7), as shown in FIG. 11A, an outer ring 23 of a pair of ball bearings 4a and 4b, The ring-shaped spacer bearing 19 sandwiched between them may be integrally formed as a cartridge bearing 14a.

In addition, as shown in FIG. 11B, the inner race 24 of the ball bearing 4b may be integrally formed with the outer peripheral surface of the shaft 1. With such a configuration, the same effect as described above can be obtained.

(Embodiment 10) FIG. 12 shows (Embodiment 10) of the present invention. The above (Embodiment 6)-
In the spindle motor 2b configured in the same manner as in the eighth embodiment, as shown in FIG. 12A, the outer ring 23 of the ball bearings 4a and 4b and the spacer bearing 19 sandwiched between the outer ring 23 and the cartridge bearing 14 are provided.
b may be integrally formed.

As shown in FIG. 12B, the inner race 24 of the ball bearing 4b may be formed integrally with the outer periphery of the shaft 3 in addition to the above structure. With such a configuration, the same effect as described above can be obtained.

(Embodiment 11) FIG. 13 shows (Embodiment 11) of the present invention. This spindle motor 2e
Is a rotary shaft type spindle motor 2e in which the rotor hub 5c is configured as a fixed side.

The same effects as described above can be obtained by applying each of the above embodiments to such a spindle motor 2e.

[0139]

As described above, according to the disk drive of the present invention, the joint area between the shaft and the ball bearing or the rotor hub and the ball bearing is divided into a plurality of areas along the circumferential direction, so that the ball bearing can be formed. The displacement of the position or posture due to bonding or light press-fitting when incorporated into the spindle motor is reduced, and RRO and NRRO can be reduced. In addition, the variation in the joining force in the joining region is reduced, and the decrease and the variation in the natural frequency of the spindle motor can be reduced. Furthermore, even if the ball bearing is deformed due to assembly, temperature change, application of pressurization, etc., NRR
It is possible to realize a high-precision rotating disk drive device which is less likely to generate O and can cope with a high density in which the frequency of the PRO due to the deformation of the disk is easily controlled.

[Brief description of the drawings]

FIG. 1 is a perspective view of a shaft and an enlarged perspective view of a rotor hub according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the spindle motor according to the embodiment.

FIG. 3 is a horizontal sectional view of the spindle motor according to the embodiment.

FIG. 4 is a schematic view showing a joint state between a ball bearing and a rotor hub according to a second embodiment of the present invention.

FIG. 5 is an enlarged perspective view of a spacer bearing and a longitudinal sectional view of a spindle motor according to a third embodiment of the present invention.

FIG. 6 is an enlarged perspective view of a spacer bearing and a longitudinal sectional view of a spindle motor according to (Embodiment 4) of the present invention.

FIG. 7 is an enlarged perspective view of a spacer bearing and a longitudinal sectional view of a spindle motor according to a fifth embodiment of the present invention.

FIG. 8 is an enlarged perspective view of a ball bearing according to (Embodiment 6) of the present invention.

FIG. 9 is an enlarged perspective view of a ball bearing according to (Embodiment 7) of the present invention.

FIG. 10 is a longitudinal sectional view of a spindle motor according to (Embodiment 8) of the present invention.

FIG. 11 is a longitudinal sectional view showing a configuration of a ball bearing according to a ninth embodiment of the present invention.

FIG. 12 is a longitudinal sectional view showing a cartridge bearing according to (Embodiment 10) of the present invention.

FIG. 13 is a longitudinal sectional view of a rotary shaft type spindle motor according to an eleventh embodiment of the present invention.

FIG. 14 is a longitudinal sectional view of a conventional spindle motor.

FIG. 15 is a schematic view for explaining a cause of NRRO caused by a shape error of an outer ring in the ball bearing of FIG. 14;

16 is a longitudinal sectional view showing a state where a disk is mounted on the spindle motor shown in FIG. 14;

FIG. 17 is a longitudinal sectional view of another conventional spindle motor different from FIG. 14;

FIG. 18 is a schematic diagram illustrating a connection state between a shaft and an inner ring of a ball bearing.

19 is a longitudinal sectional view of the spindle motor shown in FIG. 14 and an enlarged longitudinal sectional view of a ball bearing.

FIG. 20 is an enlarged cross-sectional view illustrating the application of a preload to the ball bearing shown in FIG.

FIG. 21 is a longitudinal sectional view illustrating a mounting state of ball bearings of the spindle motor shown in FIG. 14 and the spindle motor shown in FIG. 17;

[Explanation of symbols]

 3a shaft 4a, 4b ball bearing 5a-5c rotor hub 12 convex portion 13 convex portion 14 cartridge bearing 19 spacer bearing 20 adhesive 23 outer ring 24 inner ring 25 ball 26 joining area 27 gap

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 21/22 H02K 21/22 M 5H621 // F16C 25/08 F16C 25/08 F term (reference) 3J012 AB04 AB11 BB03 CB04 DB12 DB13 DB14 FB10 HB02 3J017 AA01 DA01 DA02 DB07 DB10 3J101 AA02 AA43 BA77 FA41 FA46 5D109 BB04 BB05 BB13 BB16 BB27 5H607 AA04 BB01 BB04 BB07 BB14 BB17 CC01 CC08 DD02J03 GG01 GG08

Claims (21)

[Claims] 1. A ball bearing is provided between an outer periphery of a shaft and an inner periphery of a rotor hub to rotatably support the rotor hub with respect to the shaft. An outer peripheral surface of the shaft and an inner peripheral surface of the ball bearing are provided. A disk drive device in which the joining region of the above is divided into a plurality of regions along the circumferential direction. 2. A ball bearing is provided between an outer periphery of a shaft and an inner periphery of a rotor hub to rotatably support the rotor hub with respect to the shaft. A disk drive device in which the joining region of the above is divided into a plurality of regions along the circumferential direction. 3. The disk drive according to claim 1, wherein a plurality of projections are provided on an outer peripheral surface of the shaft to divide the joining region into a plurality of regions. 4. The disk drive according to claim 1, wherein a plurality of recesses are provided on an outer peripheral surface of the shaft, and the joining region is divided into a plurality of regions. 5. The disk drive according to claim 2, wherein a plurality of projections are provided on an inner peripheral surface of said rotor hub to divide said joining region into a plurality of regions. 6. The disk drive according to claim 2, wherein a plurality of recesses are provided in an inner peripheral surface of said rotor hub, and said joining region is divided into a plurality of regions. 7. The divided joining region is uniformly arranged on the entire circumference of the shaft, and the number of divisions is a natural number represented by Z / n where Z is the number of balls of a ball bearing and n is a natural number. The disk drive device according to claim 1 or claim 2. 8. The divided joining areas are uniformly arranged on the entire circumference of the shaft, and the number of divisions is the product of Z and n when Z is the number of balls of a ball bearing and n is a natural number (Z × n). The disk drive device according to claim 1 or 2, wherein 9. A pair of ball bearings having a ring-shaped spacer bearing interposed between opposed outer rings is provided between an outer periphery of a shaft and an inner periphery of a rotor hub, and the rotor hub is rotatable with respect to the shaft. A disk drive device that applies an axial load to the inner ring side of the pair of ball bearings, wherein a contact point between the outer ring of the pair of ball bearings and the spacer bearing is
A plurality of disk drives each provided along the circumferential direction. 10. The contact point between the outer ring of the ball bearing and the spacer bearing is provided at equal intervals over the entire circumference of the ball bearing, and when Z is the number of balls of the ball bearing and n is a natural number, Z / Z 10. The disk drive according to claim 9, wherein the disk drive is a natural number represented by n. 11. A contact point between the outer ring of the ball bearing and the spacer bearing is provided at equal intervals over the entire circumference of the ball bearing, and Z is the number of balls of the ball bearing, and n is a natural number when n is a natural number. Product of n (Z × n)
10. The disk drive according to claim 9, wherein: 12. The disk drive according to claim 9, wherein the outer races of said pair of ball bearings and said spacer bearing are respectively joined and fixed at a plurality of locations. 13. A spacer bearing having a plurality of projections provided on a surface facing said ball bearing and bonded thereto.
3. The disk drive according to 2. 14. A spacer bearing having a plurality of recesses provided on a surface thereof facing said ball bearing.
3. The disk drive according to 2. 15. The disk drive according to claim 9, wherein the axial load applied to the inner race of the ball bearing is distributed to at least two places in the circumferential direction. 16. An axial load applied to the ball bearing inner ring is distributed along a circumferential direction to a natural number portion represented by Z / n where Z is the number of balls of the ball bearing and n is a natural number. The disk drive according to claim 9. 17. An axial load applied to the ball bearing inner ring is expressed by a product (Z × n) of Z and n when Z is the number of balls of the ball bearing and n is a natural number along the circumferential direction. 10. The disk drive device according to claim 9, wherein the disk drive device is distributed to the locations where the operations are performed. 18. The disk drive according to claim 9, wherein said spacer bearing is formed integrally with said rotor hub. 19. The method according to claim 15, wherein the outer ring surfaces of the pair of ball bearings facing each other and a ring-shaped spacer bearing sandwiched therebetween are integrally formed as a cartridge bearing. Disk drive. 20. The method according to claim 9, wherein the outer races of the pair of ball bearings facing each other, the spacer bearing and the rotor hub interposed therebetween are integrally formed as a cartridge bearing. Disk drive. 21. A disk drive according to claim 1, wherein said rotor hub is a fixed base.