JP2001167537A - Bearing mechanism, pivot device with bearing mechanism, and spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide at low cost a bearing mechanism which has superior assembling performance and suppress the production of contaminative substances. SOLUTION: On the upper end side of a shaft member 61, an upper support member 111 is arranged above the upper end surface 611 of the shaft member 61. This upper support member 111 has an upper recessed abutting surface 111 which abuts against the upper end surface 611 of the shaft member 61. The upper abutting surface 112 while abutting against the upper end surface 611 of the shaft member 61 with specific contact pressure to the shaft member 61 through a contact pressure adjusting mechanism pivotally supports the shaft member 61 on the upper side. On the lower end side of the shaft member 61, pivot ?supporting constitution is provided similarly to the upper end side. Consequently, the shaft member 61 can be supported rotatably on an axis PA of rotation without using any bearing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing mechanism for rotatably supporting a shaft member having a rotation axis around the rotation axis, a pivot device having the bearing mechanism, and a spindle motor.

[0002]

2. Description of the Related Art Conventionally, in a magnetic disk drive, one or more magnetic disks (recording media) are driven to rotate by a motor, and a magnetic head is arranged on both sides or one side of each magnetic disk. Plays information recorded on a disk or writes information on a magnetic disk. The magnetic head is held by an arm of a head actuator, and when the arm is driven to rotate about a predetermined rotation axis, the magnetic head moves in the radial direction of the magnetic disk by the rotation of the arm. Positioned.

[0003] In a conventional magnetic disk drive, in order to rotate a magnetic disk or to rotate a magnetic head, for example, it is described in Japanese Patent Application Laid-Open Nos. 5-205413 and 6-235419. As described above, a bearing mechanism in which two ball bearings are superimposed in two stages, upper and lower, is employed.

[0004]

Incidentally, among components constituting a spindle motor for rotating a magnetic disk and a pivot device for rotating an arm, bearings are more expensive than other components, and the spindle motor and the pivots are expensive. It accounts for the majority of equipment costs. In particular,
The conventional bearing mechanism uses two bearings, and this is one of the main factors that increase the product cost. Further, when the number of bearings increases, the following problems occur in addition to the cost.

First, as the number of bearings increases, the number of assembling steps also increases, and there is a problem that the manufacturing steps become complicated.

In addition, oil mist is generated from the bearings, and outgas is generated from the adhesive for fixing the bearings, which becomes a substance that contaminates a clean space formed in the magnetic disk device, and is generated in the magnetic disk device. May have adverse effects. Such contaminants increase with the number of bearings, and it is desired to reduce the number of bearings.

In addition, a ball generated due to an error in the amount of adhesive applied to the ball bearing and the amount of preload applied in the manufacturing process of the device using the bearing, and the rolling surfaces of the inner and outer races holding the ball. The contact amount (contact area) and contact pressure of the ball, the ball surface or the rolling surface flaws caused by the application of external impact, etc. to the ball bearing,
Due to the distortion or the like, problems such as generation of noise and vibration or deterioration of rotation accuracy and friction torque are likely to occur, which causes difficulty in maintaining the productivity or quality of the apparatus.

Also, the natural frequency of the device using this bearing becomes unstable due to the variation in the contact amount and contact pressure between the ball and the rolling surface caused by the error in the amount of adhesive applied or the amount of preload applied. For example, in the case of a pivot device, when the natural frequency becomes unstable, it resonates at a certain frequency with other components of the magnetic disk device such as a spindle motor, and vibration and noise are further deteriorated, or the natural frequency of the pivot device is If the data overlaps with the sampling frequency of the information (data) recorded on the magnetic disk, there arises a problem that the information cannot be read or written.

Further, the following problems occur in a pivot device employing a conventional bearing mechanism, for example, the pivot device described in the above-mentioned Japanese Patent Application Laid-Open No. 5-205413. The contents will be described.

In recent years, with the increase in capacity of magnetic disk devices, the density of recording tracks on the recording surface of magnetic disks has been increasing. At the same time, there is a demand for an improvement in the processing speed of a device using the magnetic disk device. In order to satisfy this demand, it is necessary to move the magnetic head as quickly and accurately as possible on a recording track on which desired information is recorded, and to shorten the seek time.

However, in the conventional pivot device,
A pivot shaft is provided along the rotation axis,
The inner ring of the ball bearing is fixed to the outer surface in two steps by an adhesive or the like with a fastening member, and the actuator body rotates about the rotation axis with respect to the pivot shaft by these two steps of ball bearings. It is free. The arm is attached to the rotatable actuator body as described above, and is rotatable around the rotation axis. Therefore, the size of the head actuator has been increased, and it has become impossible to satisfy the above-mentioned requirements (shortening of seek time, etc.) in terms of controllability such as response to a control signal and followability.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its first object to provide a low-cost bearing mechanism having excellent assemblability and capable of suppressing generation of contaminants.

It is a second object of the present invention to provide a pivot device and a spindle motor having the above-mentioned bearing mechanism.

It is a third object of the present invention to provide a pivot device which is small and lightweight and has excellent controllability.

[0015]

A bearing mechanism according to the present invention is a bearing mechanism for supporting a shaft member having a rotation axis so as to be rotatable around the rotation axis.
In order to achieve the above object, a first support member having a first contact surface that abuts on one end surface of the shaft member on the rotation axis, and abuts on the other end surface of the shaft member on the rotation axis. A second support member having a second contact surface. And one surface of the one end surface and the first contact surface is formed as a substantially hemispherical or substantially conical convex surface, and the other surface is formed as a concave surface engageable with the convex surface, Further, one of the other end surface and the second contact surface is formed as a substantially hemispherical or substantially conical convex surface, and the other surface is formed as a concave surface engageable with the convex surface. I have.

In the bearing mechanism configured as described above, a pivot support structure is adopted on both ends of the shaft member in order to rotatably support both ends of the shaft member. That is, on one end side of the shaft member, a first support member having a first contact surface in contact with one end surface of the shaft member is provided, and one of the one end surface and the first contact surface is substantially hemispherical. And the other surface is formed as a concave surface engageable with the convex surface. The other end of the shaft member has the same configuration as the one end. That is, a second support member having a second contact surface that contacts the other end surface of the shaft member is provided, and one of the other end surface and the second contact surface is formed into a substantially hemispherical or substantially conical convex surface. It is formed and the other surface is formed as a concave surface capable of engaging with the convex surface. For this reason,
The shaft member can be rotatably supported without providing a bearing, and the disadvantage that has occurred in the conventional example in which the shaft member is rotatably supported by the bearing is eliminated.

Here, in order to suppress the swing of the shaft member, it is desirable to further provide contact pressure adjusting means for adjusting the contact pressure applied to the shaft member by the first support member and the second support member. As the contact pressure adjusting means, for example, the first
A first holding member for holding the support member, a second holding member for holding the second support member, and a fastening member for fastening the first holding member and the second holding member, the first holding by the fastening member The contact pressure may be adjusted by changing the fastening state between the member and the second holding member. Note that the first support member and the first holding member may be configured separately from each other, or may be integrally formed. On the other hand, the second support member and the second holding member may be formed separately or may be integrally formed.

Further, as another embodiment of the contact pressure adjusting means,
Contact pressure adjusting means for adjusting the contact pressure applied to the shaft member by the first support member and the second support member by urging the first contact surface toward one end surface of the shaft member may be provided.

It is desirable that the convex surface and the concave surface are made of materials different from each other in strength or coefficient of thermal expansion. With such a configuration, problems such as adhesion and seizure of the convex surface and the concave surface may occur. Can be suppressed. Further, in such a configuration, the shaft member and the first and second support members are all under the above conditions (the convex surface and the concave surface are made of materials different from each other in strength or coefficient of thermal expansion). The configuration may be such that it satisfies, or a plurality of parts may be combined to form the whole, but the parts corresponding to the convex or concave portions may satisfy the above conditions.

In order to make one end surface or the other end surface of the shaft member convex, for example, a ball member may be pressed into the end surface and the surface of the ball member may be made convex. Further, in order to make the first contact surface or the second contact surface a convex surface, similarly to the case of the shaft member, for example, a ball member is pressed into the contact surface, and the surface of the ball member may be a convex surface. .

The pivot device according to the present invention is a pivot device for supporting an arm for holding at least a head for reproducing information on a storage medium so as to be rotatable about a predetermined rotation axis. In order to achieve the second and third objects, a shaft member having a rotation axis, and rotatably disposed around the rotation axis with the rotation axis coinciding with the rotation axis. 6. The bearing mechanism according to claim 1, which supports the shaft member rotatably around the rotation axis. Then, the arm is fixed to the shaft member.

In the pivot device configured as described above,
A bearing mechanism according to any one of claims 1 to 5 is provided. The arm is directly fixed to a shaft member rotatably supported by the bearing mechanism. For this reason, the pivot device is smaller and lighter than the conventional pivot device described in, for example, JP-A-5-205413, and as a result, the natural frequency of the pivot device is increased and controllability is improved.

A spindle motor according to the present invention is a spindle motor for rotating at least one or more storage media. In order to achieve the second object, a shaft member having a rotation axis and a shaft member having a rotation axis are provided. 6. The bearing mechanism according to claim 1, which is rotatably supported around the rotation axis, a rotor hub attached to the shaft member, a driving magnet fixed to the rotor hub, and the driving mechanism. And a stator disposed to face the magnet.

In the spindle motor thus configured, the bearing mechanism according to any one of claims 1 to 5 is provided. A rotor hub is fixed to a shaft member rotatably supported by the bearing mechanism, and a magnetic field generated from a driving magnet fixed to the rotor hub and a magnetic field generated by a stator disposed opposite to the driving magnet. The shaft member is rotated by interaction with a magnetic field generated by energization.

[0025]

FIG. 1 is an internal plan view of a magnetic disk drive provided with a bearing mechanism according to the present invention. 2 and 3 are a sectional view taken along line AA and a sectional view taken along line BB of FIG. 1, respectively. As shown in FIG. 1, in the magnetic disk drive, a plurality of magnetic disks (recording media) 3 are mounted on a spindle motor 2 in a housing 1.
Is mounted and driven to rotate about the rotation axis RA. Although a plurality of magnetic disks 3 are provided here, the same applies to a single disk.

On the other hand, a head actuator 4 is provided in the vicinity of the magnetic disk 3 so as to be rotatable around a rotation axis PA. In this head actuator 4, a predetermined number of magnetic heads 5 are provided according to the number of magnetic disks 3 and corresponding to both surfaces or one surface of the magnetic disks, and are rotatable about a rotation axis PA by a pivot device 6. The arm 7 is attached to one end. Voice coil motor 1 for rotating head actuator 4 having arm 7 supporting magnetic head 5
Reference numeral 0 denotes a lower yoke 9a fixed to the support 1d of the housing 1, an upper yoke 9b opposed to the lower yoke 9a with a predetermined gap therebetween, and fixed to the inner surface of the lower yoke 9a to face the upper yoke 9b. And a voice coil 8b attached to a support frame 8a extending from the shaft member 61 like the arm 7. The support frame 8a and the voice coil 8b are
The head actuator 4 is located between the upper yoke 9b and the magnet 9c, and a magnetic field is generated by energizing the voice coil 8b, and the head actuator 4 rotates in the circumferential direction by interaction with the magnetic field generated by the magnet 9c. Then, the magnetic head 5 supported by the arm 7 moves in the radial direction of the magnetic disk 3 and is positioned.

Next, the structure of the pivot device 6 will be described with reference to FIG.
This will be described in detail with reference to FIGS. The pivot device 6 includes a bearing mechanism 100 according to the first embodiment of the present invention.
It is equipped with. As shown in FIGS. 2 and 3,
The shaft member 61 is rotated by the bearing
A is rotatably supported on A. The arm 7 and the support frame 8a are directly attached to the shaft member 61.

In the bearing mechanism 100, the shaft member 61 to which the arm 7 and the support frame 8a are directly mounted.
Are pivotally supported on both ends of the shaft member 61 in order to rotatably support the shaft member around the rotation axis PA. That is, on the upper end side of the shaft member 61, the upper support member 111 is disposed at a position above the upper end surface 611 of the shaft member 61. The upper support member 111 has a concave upper surface 112 that is in contact with the upper end surface 611 of the shaft member 61.
In this embodiment, as shown in FIG.
The upper end surface 611 of the first support member 111 is formed in a substantially conical convex surface, whereas the upper contact surface 112 of the upper support member 111 has a larger radius of curvature than the radius of curvature of the upper end surface 611. The upper contact surface 112 pivotally supports the shaft member 61 on the upper side while the upper contact surface 112 contacts the upper end surface 611 of the shaft member 61 with a predetermined contact pressure against the shaft member 61 by a contact pressure adjusting mechanism described later. .

On the other hand, the lower end side of the shaft member 61 is also provided with a pivot support structure, similarly to the upper end side. Specifically, the lower end surface 61 of the shaft member 61
2, a lower support member 121 is provided.
The lower support member 121 has a concave contact surface 122 that is in contact with the lower end surface 612 of the shaft member 61. In this embodiment, the shaft member 61
Is formed in a substantially conical convex surface, whereas the lower contact surface 122 of the lower support member 121 has a larger radius of curvature than the radius of curvature of the lower end surface 612. Therefore, the lower contact surface 122 pivotally supports the shaft member 61 on the lower side while contacting the lower end surface 612 of the shaft member 61 with a predetermined contact pressure against the shaft member 61 by the contact pressure adjusting mechanism.

Next, the contact pressure adjusting mechanism will be described.
In this embodiment, the contact pressure adjusting mechanism 130 includes an upper holding member 131 that holds the upper supporting member 111 and a lower holding member 132 that holds the lower supporting member 121. The upper holding member 131 and the lower holding member 132 are opposed to each other so as to sandwich the shaft member 61 between the upper supporting member 111 and the lower supporting member 121, and are fastened to each other by two screws 133, 134. Of these two screws, the screw 133 farthest from the rotation axis PA
Denotes a fastening screw.

On the other hand, the screw 134 closer to the rotation axis PA functions as a contact pressure adjusting screw for adjusting the contact pressure by changing the fastening state between the upper holding member 131 and the lower holding member 132. . That is, when the degree of tightening by the contact pressure adjusting screw 134 is loosened, the upper support member 1
The distance between the lower support member 121 and the lower support member 121 increases, and the contact pressure decreases. Conversely, when the tightening is strengthened, the above-mentioned interval is narrowed and the contact pressure is increased. As described above, the contact pressure adjusting screw 134 corresponds to the component “fastening member” of the present invention.

As described above, according to the bearing mechanism 100 of this embodiment, since the pivot support structure is employed at the upper and lower ends of the shaft member 61, the shaft member 61 is rotated without using a bearing. It can be rotatably supported around the axis PA. As a result, the number of bearings can be reduced, the cost can be reduced, the assemblability is excellent, and the generation of pollutants can be suppressed. Further, by equipping the pivot device with the bearing mechanism 100 having such effects, effects such as cost reduction of the pivot device, improvement of assemblability of the pivot device, and suppression of generation of contaminants from the pivot device can be obtained.

The bearing mechanism 100 is provided with a contact pressure adjusting mechanism 130 for changing the distance between the upper contact surface 112 and the lower contact surface 122 so that the upper support member 111 and the lower support member 121 are formed. The contact pressure applied to the shaft member 61 can be adjusted. Therefore, the swing of the shaft member 61 can be suppressed by appropriately adjusting the contact pressure. In particular, in a magnetic disk drive, it is necessary to move the magnetic head 5 accurately on a recording track on which desired information is recorded, and the effect of suppressing the swing of the shaft member 61 is great.

In the pivot device 6 equipped with the bearing mechanism 100, the arm 7 and the support frame 8a are directly attached to the shaft member 61 so as to be rotatable around the rotation axis PA. The following specific effects can be obtained. That is, in the conventional pivot device, as described in, for example, Japanese Patent Application Laid-Open No. 5-205413, an actuator body is rotatably attached to a pivot shaft via two bearings, and an arm is further attached to the actuator body. By fixing, the arm is configured to be rotatable about the rotation axis.
Therefore, there is a problem that controllability such as responsiveness and controllability to a control signal is reduced due to an increase in the size of the head actuator.

On the other hand, in the pivot device 6 according to the above embodiment, the arm 7 is directly connected to the shaft member 6 without providing a bearing and an actuator body.
Since it is fixed to 1, it is smaller and lighter than the conventional device. Along with this weight reduction, the natural frequency of the pivot device becomes higher, and the controllability is improved by that much,
As a result, the magnetic head 5 can be moved as quickly and accurately as possible on the recording track on which desired information is recorded, and the seek time can be reduced.

In the above embodiment, the contact pressure is adjusted by the contact pressure adjusting screw 134. However, as shown in FIG. 5, the contact pressure is adjusted by a biasing member such as a spring or an elastic sheet. You may. Hereinafter, the bearing mechanism according to the second embodiment will be described with reference to FIG.

FIG. 5 shows a second embodiment of the bearing mechanism according to the present invention.
It is a figure showing an embodiment. The second embodiment is largely different from the previous embodiment only in the configuration for adjusting the contact pressure, and the other configurations are the same. Therefore, the same components are denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, a guide groove 135 dug down along the rotation axis PA is provided on the lower surface side of the upper holding member 131 as shown in FIG. The support member 111 is provided movably along the rotation axis PA. An urging member 136 such as a spring or an elastic sheet is disposed between the back surface of the upper support member 111 and the bottom surface of the guide groove 135, and the upper support member 111 is attached to the upper end surface 611 of the shaft member 61. I'm going. Therefore, by appropriately setting the urging force of the urging member 136 in advance, the contact pressure can be adjusted, and the swing of the shaft member 61 can be suppressed, as in the first embodiment.

In the first and second embodiments,
The upper holding member 131 and the lower holding member 132 are fastened and fixed to each other with fastening screws 133.
As shown in FIG. 7 and FIG. 7, the support member may be held by a holding member 137 obtained by integrally molding the both. Further, the support member and the holding member may be integrated. In addition,
6 and 7, the lower support member 121 is attached to the holding member 1.
37, while the upper support member 111 is urged by the urging member 136 toward the upper end surface 611 of the shaft member 61 to adjust the contact pressure as in the second embodiment (FIG. 5). I have.

The above embodiment relates to a pivot device equipped with the bearing mechanism according to the present invention, but this bearing mechanism is also applicable to a spindle motor of a magnetic disk drive. Hereinafter, the details will be described with reference to FIGS. 8 and 9.

FIG. 8 is a view showing one embodiment of a spindle motor equipped with a bearing mechanism according to the present invention.
The shaft member 21 of this motor is rotatably supported around a rotation axis RA by a bearing mechanism 100 configured in the same manner as in the previous embodiment.

In this bearing mechanism 100, the pair of upper and lower support members 111 and 121 are connected to the rotation axis RA of the shaft member 21.
Is placed on top. Of these, the lower support member 121
Is held by the housing base 1a of the magnetic disk drive. In this embodiment, the housing base 1a and the lower support member 121 are formed separately, but they may be integrally formed.

As in the previous embodiment, the lower support member 121 is formed with a lower contact surface 122 that is in contact with the lower end surface 212 of the shaft member 21 in a concave shape.
The lower end surface 212 of the shaft member 21 is formed in a substantially conical convex surface, while the lower support member 121
Has a larger radius of curvature than the radius of curvature of the lower end surface 212. Therefore, the shaft member 21 is pivotally supported on the lower side while the lower contact surface 122 contacts the lower end surface 212 of the shaft member 21.

On the other hand, the upper support member 111 is provided in the guide groove 1c of the housing lid 1b, and is movably held along the rotation axis RA. As in the previous embodiment, the upper support member 111 has a concave upper surface 112 that is in contact with the upper end surface 211 of the shaft member 21. Then, the upper end surface 2 of the shaft member 21
11 is formed in a substantially conical convex surface, whereas the upper contact surface 112 of the upper support member 111 has a larger radius of curvature than the radius of curvature of the upper end surface 211. And
The upper contact surface 112 is pressed against the shaft member 21 with a predetermined contact pressure against the shaft member 21 by an urging member described below.
The shaft member 21 is pivotally supported on the upper side while being in contact with the upper end surface 211 of the shaft member 21.

A fine adjustment screw 138 is attached to the housing lid 1b so as to correspond to the guide groove 1c, and the tip surface of the fine adjustment screw 138 is the bottom surface of the guide groove 1c. An urging member 136 such as a spring or an elastic sheet is arranged between the bottom surface and the back surface of the upper support member 111 to urge the upper support member 111 toward the upper end surface 211 of the shaft member 21. I have.

Therefore, in this embodiment, the urging member 136 not only gives the upper support member 111 and the lower support member 121 a contact pressure to the shaft member 21 but also turns the fine adjustment screw 138 to rotate the housing lid part. 1
The contact pressure can be finely adjusted by moving forward and backward with respect to b. The process of finely adjusting the contact pressure using the fine adjustment screw 138 as described above can be applied to the bearing mechanism shown in FIGS. 5 and 6. On the other hand, it goes without saying that a contact pressure adjusting mechanism similar to that employed in the pivot device 6 may be applied to the present embodiment.

As described above, the shaft member 21 rotatably supported by the bearing mechanism 100 around the rotation axis RA.
The stator 22 surrounds the housing base 1
a. The stator 22 includes a stator core 22a externally fitted to the shaft member 21, and a winding 22b wound therearound.

The rotor hub 23 is fixed to the shaft member 21. Here, the rotor hub 23 is formed of stainless steel, aluminum, or an aluminum alloy according to the material of the magnetic disk. The magnetic disk 3 is mounted outside the cylindrical portion of the rotor hub 23.

A driving rotor magnet 24 is fitted inside the cylindrical portion of the rotor hub 23, and the rotor magnet 24 is connected to the stator 2 via a predetermined gap.
2 are disposed opposite to each other. Therefore, the stator 2
2, a magnetic field is generated from the stator 22, and the interaction between the magnetic field and the magnetic field generated from the rotor magnet 24 causes the magnetic disk 3 to rotate together with the shaft member 21, the rotor hub 23, and the rotor magnet 24. Rotate around RA.

As described above, according to the spindle motor 2 of this embodiment, since the pivot support structure is employed at the upper and lower ends of the shaft member 21, the shaft member 21 can be rotated without using a bearing. It can be supported rotatably around the center RA. As a result, the number of bearings can be reduced, the cost of the motor can be reduced, the motor can be easily assembled, and the generation of pollutants can be suppressed.

The upper support member 111 and the lower support member 121 are moved by the urging member 136 to the shaft member 21.
And a fine adjustment screw 138.
Since the contact pressure can be fine-adjusted, the contact pressure can be adjusted with high precision, and the swinging of the shaft member 61 can be reliably suppressed.

In the spindle motor according to this embodiment, the contact pressure is adjusted by directly expanding and contracting the biasing member 136. However, as shown in FIG. 9, for example, the contact pressure is adjusted by indirectly expanding and contracting the urging member 136. You may. More specifically, in the embodiment shown in FIG.
The housing base 1a and the housing lid 1b are connected by fine adjustment screws 139. Then, by adjusting the degree of tightening by the fine adjustment screw 139, the housing base 1a and the housing lid 1b are relatively moved to control the contact pressure by the urging member 136.

The present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention. For example, both end surfaces 211 and 212 of the shaft member 21
And the contact surfaces 112 and 122 of the support members 111 and 121 are in contact with each other and rub against each other due to the rotating operation of the shaft member 21, so that the shaft member 21 and the support members 111 and 1 are rubbed.
21 is preferably made of a material having a different strength or coefficient of thermal expansion. By selecting such a material, adhesion and seizure between the shaft member 21 and the support members 111 and 121 are suppressed. Therefore, the life of the spindle motor 2 can be extended. Here, in selecting the material in this manner, the entirety of each of the support members 111 and 121 and the shaft member 21 is made of the above-mentioned conditions (the convex and concave surfaces are made of materials different from each other in strength or coefficient of thermal expansion). ) May be satisfied, or a plurality of parts may be combined to form the whole, but parts corresponding to convex or concave parts may satisfy the above condition. Good. In addition, about these improvement examples, the pivot device 6 is completely the same.

In order to make one end surface or the other end surface of the shaft member convex, for example, a ball member may be pressed into the end surface and the surface of the ball member may be made convex. Further, in order to make the first contact surface or the second contact surface a convex surface, similarly to the case of the shaft member, for example, a ball member is pressed into the contact surface, and the surface of the ball member may be a convex surface. .

In the above embodiment, the convex surface has a substantially conical shape. However, the convex shape is not limited to a substantially conical shape, and may be formed in a substantially spherical shape. In addition, while both end surfaces of the shaft member are formed as convex surfaces, and the contact surfaces of the support members are formed as concave surfaces, these surface shapes may be interchanged at both ends or at one end. In short, at one end side of the shaft member, one of the one end surface and the abutting surface is formed as a substantially hemispherical or substantially conical convex surface, and the other surface is engaged with the convex surface. What is necessary is just to form in the concave surface which can be combined. Also, on the other end side, the other end face,
It is sufficient that one of the contact surfaces that come into contact therewith is formed as a substantially hemispherical or substantially conical convex surface, and the other surface is formed as a concave surface that can engage with the convex surface.

Further, the application of the bearing mechanism according to the present invention is not limited to the above-mentioned pivot device and spindle motor, but is generally applied to any device having a bearing mechanism for rotatably supporting a shaft member around a predetermined rotation axis. Can be applied to

[0057]

As described above, according to the first aspect of the present invention, since the pivot support structure is provided at both ends of the shaft member, the number of bearings can be reduced as compared with the conventional example. Thus, the cost can be reduced, the assemblability is excellent, and the generation of pollutants can be suppressed.

According to the second to fifth aspects of the present invention, since the contact pressure adjusting means for adjusting the contact pressure applied to the shaft member by the first support member and the second support member is further provided, an appropriate The contact pressure can be applied to the shaft member, and the swing of the shaft member can be effectively suppressed.

According to the invention described in claim 6, the bearing mechanism according to any one of claims 1 to 5 is used as a bearing mechanism for rotatably supporting the shaft member about the rotation axis. By reducing the number, the effects of reducing the cost of the pivot device, improving the assemblability of the device, and suppressing the generation of contaminants from the pivot device can be obtained. Also, since the arm is directly fixed to the shaft member,
It is possible to reduce the size and weight as compared with the conventional device. With the weight reduction, the natural frequency of the pivot device is increased, and the controllability is improved accordingly. As a result, the magnetic head is moved on the recording track where desired information is recorded as quickly as possible. Moreover, it is possible to move accurately and to reduce seek time.

According to the seventh aspect of the present invention, the bearing mechanism according to any one of the first to fifth aspects is used as a bearing mechanism for rotatably supporting the shaft member about the rotation axis. By reducing the number, effects such as cost reduction of the spindle motor, improvement of motor assemblability, and suppression of generation of contaminants from the spindle motor can be obtained.

[Brief description of the drawings]

FIG. 1 is an internal plan view of a magnetic disk drive provided with a bearing mechanism according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a partially enlarged view of the bearing mechanism shown in FIGS. 2 and 3;

FIG. 5 is a view showing a second embodiment of the bearing mechanism according to the present invention.

FIG. 6 is a view showing a third embodiment of the bearing mechanism according to the present invention.

FIG. 7 is an exploded perspective view of the bearing mechanism of FIG. 6;

FIG. 8 is a diagram showing one embodiment of a spindle motor equipped with a bearing mechanism according to the present invention.

FIG. 9 is a view showing another embodiment of a spindle motor equipped with a bearing mechanism according to the present invention.

[Explanation of symbols]

 2 spindle motor 3 magnetic disk (recording medium) 4 head actuator 5 magnetic head 6 pivot device 7 arm 21 shaft member 22 stator 22 a stator core 22 b winding 23 rotor hub 24 rotor magnet 61 Shaft member 100: Bearing mechanism 111: Upper support member 112: Upper contact surface 121: Lower support member 122: Lower contact surface 130: Contact pressure adjusting mechanism 131: Upper holding member 132: Lower holding member 134: For contact pressure adjustment Screws 211, 611: Upper end surface 212, 612: Lower end surface PA: Rotation axis RA: Rotation axis

Continuation of the front page (72) Inventor Tadashi Hasegawa 1145-4, Takiri, Iijima-cho, Kamiina-gun, Nagano F-term (reference) in Nagano Technology Development Center, Nidec Corporation 5D068 AA01 BB01 CC12 EE13 GG07 GG25

Claims (7)

[Claims] 1. A bearing mechanism for supporting a shaft member having a rotation axis so as to be rotatable around the rotation axis, wherein a first contact abuts on one end surface of the shaft member on the rotation axis. A first support member having a surface, and a second support member having a second contact surface that contacts the other end surface of the shaft member on the rotation axis, wherein the one end surface and the first contact surface One surface is formed as a substantially hemispherical or substantially conical convex surface, and the other surface is formed as a concave surface engageable with the convex surface, and the other end surface and the second contact surface are Wherein one surface is formed as a substantially hemispherical or substantially conical convex surface, and the other surface is formed as a concave surface engageable with the convex surface. 2. A contact pressure adjustment for changing a distance between the first contact surface and the second contact surface to adjust a contact pressure applied to the shaft member by the first support member and the second support member. 2. The bearing mechanism according to claim 1, further comprising means. 3. The contact pressure adjusting means includes a first holding member that holds the first support member, a second holding member that holds the second support member, the first holding member, and the second holding member. 3. The contact pressure according to claim 2, further comprising: a fastening member configured to fasten a member, wherein the contact pressure can be adjusted by changing a fastening state between the first holding member and the second holding member by the fastening member. Bearing mechanism. 4. The bearing mechanism according to claim 3, wherein said first support member and said first holding member are integrally formed, and said second support member and said second holding member are integrally formed. 5. A contact pressure for urging the first contact surface toward the one end surface of the shaft member to adjust a contact pressure applied to the shaft member by the first support member and the second support member. The bearing mechanism according to claim 1, further comprising an adjusting unit. 6. A pivot device for supporting an arm for holding at least a head for reproducing information on a storage medium so as to be rotatable about a predetermined rotation axis, comprising a rotation axis. 2. A shaft member rotatably arranged around the rotation axis with a rotation axis coinciding with the rotation axis, and a shaft member rotatably supported around the rotation axis. 3. A pivot device, comprising: the bearing mechanism according to any one of (a) to (d), wherein the arm is fixed to the shaft member. 7. A spindle motor for rotating at least one storage medium, comprising: a shaft member having a rotation axis; and a shaft member rotatably supported around the rotation axis. And a rotor hub attached to the shaft member; a driving magnet fixed to the rotor hub; and a stator disposed to face the driving magnet. A spindle motor.