JPH0696514A - Spindle motor - Google Patents

Abstract

PURPOSE:To adjust the height of the medium receiving face of a medium support member by installing a height adjustment means which adjusts the height up to the medium receiving face from the reference face of a stator support member. CONSTITUTION:A stator 23 composed of a coil is fixed to the outer circumference of a sidewall 19 erected and installed from the central part of a stator support member 3, and it generates a magnetic field when an electric current is applied. A magnet 27 is fixed, via a yoke 25, to the inner wall of a hub 9 so as to face the stator 23. The magnet 27 generates a turning effort which turns the hub 9 with reference to the stator support member 3 by the magnetic field generated by the stator 23. The central position in the height direction of the stator 23 and the magnetization center in the height direction of the magnet 27 are arranged so as to be dislocated. Two magnetic disks 5 are mounted on the medium receiving face 7 of the hub 9 via a spacer 29 and are sandwiched between, and held by, a fixation member 31 and the medium receiving face 7. When a wear-resistant material 17 is turned and moved, a shaft 11 is moved up and down, the hub 9 is moved up and down and the height H up to the medium receiving face 7 of the hub 9 from the reference face A of the support member 3 can be adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor which is used in a magnetic disk device or the like to rotate a magnetic recording medium.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional spindle motor 1 used in a magnetic disk device. In FIG. 1, this spindle motor 1 has a medium receiving surface 7 on which a magnetic recording medium (hereinafter referred to as “magnetic disk”) 5 is placed on a stator support member 3 fixed to a magnetic disk device main body (not shown). A medium support member (hereinafter referred to as “hub”) 9 is rotatably arranged.

A rotating shaft 11 is provided at the center of the hub 9, and an axially lower end of the rotating shaft 11 is rotatably supported by a stator support member 3 by a thrust bearing 13. This thrust direction bearing 13 is
Hard balls 15 arranged at the lower end of the stator and the stator support member 3
And an abrasion resistant material 17 fixed to the.

The outer circumference of the rotary shaft 11 in the axial direction is
It is rotatably supported by a radial bearing 21. The radial bearing 21 is supported by the inner wall of the side wall 19 which is erected from the center of the stator support member 3.
As the radial bearing 21, an oil-impregnated bearing, a dynamic pressure bearing, a magnetic fluid bearing, a resin sliding bearing, or the like is used.

A stator 23, which is a coil, is fixed to the outer periphery of the side wall 19 provided upright from the central portion of the stator support member 3 to generate a magnetic field when energized. Further, the yoke 2 is provided on the inner wall of the hub 9 so as to face the stator 23.
The magnet 27 is fixed via 5. This magnet 27
Generates a rotational force that rotates the hub 9 with respect to the stator support member 3 by the magnetic field generated by the stator 23. Further, the center position of the stator 23 in the height direction is deviated from the magnetization center of the magnet 27 in the height direction, and a pressing force for pressing the rotating shaft 11 toward the thrust direction bearing 13 is generated.

Two magnetic disks 5 and 5 are placed on the medium receiving surface 7 of the hub 9 via a spacer 29, and the medium receiving surface 7 is fixed by a fixing member 31 fixed to the upper surface of the hub 9 with screws 33. It is clamped and fixed between the surface 7 and the surface 7.

In the spindle motor 35 as described above, the support structure of the rotating shaft 11 of the hub 9 is changed from a ball bearing to correspond to miniaturization, cost reduction, high performance of the magnetic disk device.
There is a tendency to substitute oil-impregnated bearings, dynamic pressure bearings, magnetic fluid bearings, resin sliding bearings, etc. Unlike ball bearings, these bearings
Only the radial direction (the direction that supports the outer circumference of the rotary shaft 11) is supported, and the thrust direction (the axial direction of the rotary shaft 11) must be supported by a bearing having a different structure. As an example of this,
As shown in FIG. 3, a structure in which the hard balls 15 and the abrasion resistant material 17 are supported by contact is used.

Further, in the above spindle motor 1,
By shifting the center position in the height direction of the stator 23 and the magnetization center in the height direction of the magnet 27, a pressing force in the thrust direction (axial direction of the rotating shaft 11) is generated, and the hard balls 15 and abrasion resistance. A pressing force is generated between the hard ball 15 and the wear-resistant material 17 to keep the contact state stable, and the height from the reference surface A of the stator support member 3 to the medium receiving surface 7 of the hub 9 is high. Positioning is performed in H, that is, the thrust direction.

[0009]

In the magnetic disk device, the height of the magnetic disk 5 is important with respect to the mounting height of the recording / reading head on the magnetic disk 5. In the case where the spindle motor 1 has a structure having a flange, the reference surface A of the flange for attaching the spindle motor 1 to the magnetic disk device body and the medium receiving surface 7 of the hub 9
The dimensional accuracy of the height H is required (in this case, the accuracy of the head height from the magnetic disk device through the carriage has been obtained). When the spindle motor 1 is integrated with the main body of the magnetic disk device, the height relationship between the carriage mounting surface and the medium receiving surface 7 of the hub 9 is important (in this case, the height from the carriage reference surface to the head). Accuracy has been obtained).

In order to obtain the dimensional accuracy of the height H of the medium receiving surface 7 of the hub 9 from the reference surface A, the spindle motor 1 is conventionally used.
After assembling, the medium receiving surface 7 of the hub 9 was subjected to finishing processing to obtain height accuracy.

However, when the medium receiving surface 7 of the hub 9 is post-processed, a large load is applied to the thrust bearing 13, which may damage the thrust bearing 13 (hard ball 15, wear-resistant material 17). is there. For this reason, when the thrust bearing 13 as described above is used, there is a problem that post-processing cannot be performed.

Therefore, in order to eliminate the post-processing, it is conceivable to extremely improve the processing accuracy of the component parts.
In this case, there is a problem that the manufacturing cost of the component parts becomes high.

Therefore, an object of the present invention is to provide a magnetic disk device having a spindle motor capable of adjusting the height of the medium receiving surface of the medium supporting member.

[0014]

In order to achieve the above object, the invention according to claim 1 is a height adjusting a height from a stator support member to a medium receiving surface by moving a rotating shaft in an axial direction. It is characterized in that a height adjusting means is provided.

According to a second aspect of the present invention, in the magnetic disk drive according to the first aspect, the center of the stator in the height direction and the magnetizing center of the magnet in the height direction are displaced from each other so that the rotating shaft is thrust. It is characterized in that a pressing force for pressing the directional bearing is generated to press the medium support member toward the stator support member.

[0016]

According to the first aspect of the invention, the height of the magnetic recording medium relative to the mounting height of the head is adjusted by adjusting the height from the stator supporting member to the medium receiving surface by the height adjusting means. It is possible to set the optimum positional relationship. Further, since the height of the medium receiving surface can be easily adjusted by the height adjusting means, there is no need to post-process the medium receiving surface.
Therefore, it is possible to reduce the cost by not requiring the processing accuracy of the component parts, and to prevent an excessive pressing force from being applied to the thrust direction bearing.

According to the second aspect of the invention, the positional relationship between the magnet and the stator is shifted and the rotary shaft is pressed in the thrust direction bearing direction, whereby the rotary shaft is positioned in the thrust direction.

[0018]

Embodiments of the spindle motor according to the present invention will be described below with reference to the drawings. 1 shows a spindle motor 35 of the first embodiment, and FIG. 2 shows a spindle motor 39 of the second embodiment. The same components as those of the spindle motor 1 shown in FIG.

As shown in FIG. 1, in the spindle motor 35 of the first embodiment, a hub 9 having a medium receiving surface 7 on which a magnetic disk 5 is placed is rotatably arranged on a stator support member 3. There is.

The axial lower end of the rotary shaft 11 at the center of the hub 9 is rotatably supported by a thrust direction bearing 13 composed of a hard ball 15 and an abrasion resistant material 17 fixed to the stator support member 3. There is. The wear resistant material 17 is formed on a male screw and is screwed into a screw hole formed on the stator support member 3. Therefore, by rotating the abrasion resistant material 17, the abrasion resistant material 17 moves up and down the screw hole. The height adjusting means 37 includes the above-described screw hole of the stator support member 3 and the male screw-shaped wear resistant material 17.

The outer circumference of the rotary shaft 11 is rotatably supported by radial bearings 21 such as oil-impregnated bearings, dynamic pressure bearings, magnetic fluid bearings, resin sliding bearings and the like.

A stator 23, which is a coil, is fixed to the outer periphery of the side wall 19 provided upright from the central portion of the stator support member 3 and generates a magnetic field when energized. A magnet 27 is fixed to the inner wall side of the hub 9 facing the stator 23 via a yoke 25. The magnet 27 generates a rotational force that rotates the hub 9 with respect to the stator support member 3 by the magnetic field generated by the stator 23. In addition, the center position of the stator 23 in the height direction is offset from the magnetization center of the magnet 27 in the height direction. Therefore, a pressing force in the thrust direction (axial direction of the rotary shaft 11) is generated,
A pressing force is generated between the hard balls 15 and the wear resistant material.

Further, two magnetic disks 5 and 5 are placed on the medium receiving surface 7 of the hub 9 via a spacer 29, and sandwiched between the two by the fixing member 31.

Here, when adjusting the height from the reference surface A of the stator support member 3 to the medium receiving surface 7, by rotating the abrasion resistant material 17, the rotary shaft 11 moves up and down. , The hub 9 moves up and down. Thereby, the height H of the medium receiving surface 7 can be adjusted. A thrust force is generated by the stator 23 and the magnet 27,
The contact state between the hard balls 15 and the abrasion resistant material 17 is kept stable, and the height H from the reference surface A of the stator support member 3 to the medium receiving surface 7 of the hub 9, that is, the positioning in the thrust direction is performed. ing.

Next, a second embodiment will be described with reference to FIG. The spindle motor 39 shown in FIG.
Is provided so as to project from the central portion of the stator support member 3, and the thrust direction bearing 13 is arranged at the upper end portion of the rotating shaft 11. That is, the hard sphere 15 is arranged at the upper end of the rotary shaft 11, and the male screw-shaped wear resistant material 17 screwed into the screw hole of the hub 9 is placed on the hard sphere 15. Further, a hole 31a is formed in the center of the fixing member 31, and the head of the wear resistant material 17 is exposed from the hole 31a.

Also in this embodiment, in the height adjusting means 41, the hub 9 is moved up and down and the medium receiving surface 7 is moved up and down by rotating the abrasion resistant material 17 in the screw hole.

In the above embodiment, an example in which the spindle motor of the present invention is applied to the magnetic disk device is shown.
The present invention can be applied as a spinning motor of a floppy disk device.

[0028]

As described above, according to the spindle motor of the present invention, the height of the medium receiving surface from the stator supporting member can be easily adjusted by the height adjusting means. As a result, it becomes possible to make the machining accuracy and the assembly accuracy of each component in the height direction rougher than in the conventional case, and it is possible to reduce the manufacturing cost.

Further, structurally, the medium support member and the stator support member can be easily separated (they can be removed by applying a thrust force more than the attractive force of the stator and the magnet), so that the medium in the state where the medium is attached to the medium support member Servo track writing can be performed in the assembly unit, and it can be fitted into the motor fixed side.

Further, although there is a one-to-one correspondence between the stator side and the magnet side due to dimensional variations, any combination can be made by the height adjusting means.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a spindle motor according to the present invention.

FIG. 2 is a sectional view showing a spindle motor according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional spindle motor.

[Explanation of symbols]

 3 stator support member 5 magnetic recording medium 7 medium receiving surface 9 medium support member 11 rotating shaft 13 thrust direction bearing 21 radial direction bearing 27 magnet 35, 39 spindle motor 37, 41 height adjusting means

Claims (2)

[Claims] 1. A stator support member, a medium support member having a medium receiving surface on which a recording medium is placed, a rotary shaft provided at the center of the medium support member, and an axial end portion of the rotary shaft. A thrust direction bearing rotatably supported on the stator support member, a radial direction bearing rotatably supporting the outer circumference of the rotating shaft on the stator support member, and a magnetic field generated by energization provided on the stator support member. In a spindle motor including a stator and a magnet that is fixed to the medium supporting member facing the stator and applies a rotating force to the medium supporting member by a magnetic field generated by the stator, the spindle is moved in the axial direction. And a height adjusting means for adjusting the height from the stator supporting member to the medium receiving surface. 2. The medium support is generated by displacing the center position of the stator in the height direction and the magnetization center of the magnet in the height direction to generate a pressing force for pressing the rotating shaft toward the thrust bearing. The spindle motor according to claim 1, wherein a member is pressed toward the stator support member.