JP3158857B2 - Motor and disk device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor and a disk drive provided with the motor.

[0002]

FIG. 4 shows a conventional turntable motor 10 of a floppy disk drive. The motor 10 has a stator unit 11 and a rotor unit 12. Reference numeral 13 denotes an oil-impregnated sintered bearing as a sliding bearing. Reference numeral 14 denotes a rotating shaft, which is rotatably supported by the bearing 13. Rotating shaft 14
The turntable 15 is fitted and fixed. The rotating shaft 14 is a cut product formed by cutting a metal rod.

Since the motor 10 has a sliding bearing structure in which the rotary shaft 14 is received by the oil-impregnated sintered bearing 13, a whirl phenomenon in which the rotary shaft 14 whirls occurs. The Whirl phenomenon is a phenomenon that occurs in a sliding bearing structure, and refers to a phenomenon in which the rotating shaft periodically oscillates once every two rotations. The cause is thought to be the excitation force generated in the lubricating oil film.

[0004]

In the conventional motor 10, when the motor 10 is driven by using the micro-sense 20, and the whirling of the rotary shaft 14 is measured, one wobble occurs every two rotations. There was a runout of about 12 μm. In the turntable motor 10, the whirling of the shaft is reduced by reducing the margin for reading and writing signals from and to the floppy disk. Therefore, the motor 10 needs to have a small shaft runout.

Here, if grooves are provided on the peripheral surface of the rotating shaft 14, the whirling of the shaft can be suppressed (see "Lubrication", Vol. 20, No. 7 (1975), pages 481 to 488). . However, machining for forming a groove on the peripheral surface of the rotating shaft 14 is troublesome, and the cost of the motor increases.
Therefore, an object of the present invention is to provide a motor and a disk device that solve the above problems.

[0006]

According to the first aspect of the present invention, a step
A rotor section and a rotor section.
Bull and, rotation axis which is fixed to the center of the turntable
And the stator part is fixed to the base and the base.
A slide shaft that is in contact with the outer circumference of the above-mentioned rotary shaft
A first bearing comprising a bearing, the base and the
A second bearing between the rotary shaft and the
Is made of a porous sintered material .

According to a second aspect of the present invention, a disk is mounted.
Turntable motor that rotates the turntable
And the above-mentioned mode while placed on the turntable
To play the information on the disc
And the turntable motor has the turntable
Table and rotation fixed at the center of the turntable
A rotor portion having a shaft, a base, and fixed to the base;
Yes, from a plain bearing that is in contact with the outer circumference of the rotary shaft
And a stator portion having a first bearing, and
A second bearing between the base and the turntable;
And the rotating shaft is made of a porous sintered material.
The configuration is as follows.

[0008]

According to the first aspect of the present invention, the rotary shaft is made of a porous sintered material, and the characteristic that the rotary shaft is originally provided with a porous material is a film of oil or air between the rotary shaft and the slide bearing. Act so as not to generate an exciting force. The structure having the turntable motor in which the rotating shaft is made of a porous sintered material according to claim 1 acts to suppress the whirling of the disk.

[0009]

FIG. 1 shows a turntable motor 30 according to an embodiment of the present invention. The motor 30 includes a stator 31
And a rotor section 32. The stator portion 31 includes a base 33, a flat coil 34 on the base 33, and an oil-impregnated sintered bearing 3 as a sliding bearing fixed to the base 33.
And 5.

The rotor section 32 includes a rotating shaft 36 which is an essential part of the present invention, and a turntable 3 fixed to the rotating shaft 36.
7, a substantially annular rotor yoke 38 fitted and fixed to the turntable 37, and an annular rotor magnet 39 fixed to the lower surface of the rotor yoke 38. The lower (base) portion of the rotating shaft 36 is fitted to the oil-impregnated sintered bearing 35, and the rotating shaft 36 is connected to the oil-impregnated sintered bearing 3.
5 rotatably supported.

A ball bearing 40 is provided between the turntable 37 and the base 33. Here, the rotating shaft 36
Is a sintered part formed by sintering stainless steel (SUS) powder in a predetermined mold. Therefore, the manufacturing cost of the rotating shaft 36 is lower than that of the rotating shaft which is a conventional cut product. Rotation shaft 36 is porous, its peripheral surface in FIG. 2 (A), having a roughness indicated by the line I.

As is clear from the surface roughness of the rotary shaft 14 of the conventional machined product shown by the line II in FIG. 1B, the peripheral surface of the rotary shaft 36 is rough. When the motor 30 was driven and the amount of runout of the rotating shaft 36 was measured using the microsense 20, the runout once every two rotations was sufficiently suppressed.
It was 5 μm. This deflection amount is about 3 μm smaller than that of the conventional motor 10. Therefore, it can be seen that the Whirl phenomenon is suppressed in the motor 30 as compared with the conventional motor 10. This is considered to be due to the fact that the porosity of the rotating shaft 36 suppresses the exciting force generated in the lubricating oil film.

FIG. 3 shows the turntable motor 3 described above.
0 shows a floppy disk drive 50 in which 0 is incorporated.
The floppy disk drive 50 is provided with a motor 51 for the turntable, a cartridge holder 52,
A head carriage 54 having a magnetic head 53, a carriage moving mechanism 55, and the like are attached.
The cartridge 61 inch floppy disk 60 are accommodated is inserted in the X ₁ direction is used.

When the cartridge 61 is mounted, the floppy disk 60 is mounted on the turntable 37, the motor 30 starts, and the floppy disk 60 rotates. Further, the carriage moving mechanism 55 operates, and the magnetic head 53 moves in the X ₁ and X ₂ directions together with the head carriage 54 to access a predetermined track of the floppy disk 60 and read information of this track or read the information of this track. Information is written to

[0015] because it is suppressed whirling of the rotary shaft 36 of the motor 30, also becomes smaller degree whirling of the floppy disk 60. Therefore, the margin for reading and writing information is not narrowed. That is, in the floppy disk device 50, the deterioration of the information read / write margin is suppressed. Further, the turntable motor 30 can be applied to a magneto-optical disk device and an optical disk device, and has the same effects as described above.

[0016]

As described above, according to the first aspect of the present invention, the first bearing, which is a sliding bearing, supports the first bearing.
The rotating shaft that rotates while rotating is made of a porous sintered material, and
And a second bearing between the base and the turntable.
Since it has a girder configuration, it is possible to suppress the whirl phenomenon without performing processing for forming a groove on the peripheral surface of the rotating shaft. That is, compared to a motor in which a groove is formed on the peripheral surface of the rotating shaft,
A motor that is inexpensive and that can suppress the Whirl phenomenon can be realized.

According to the invention of claim 2, the turntable
Motor can suppress the whirl phenomenon,
Swaying is suppressed, and the margin for reading and writing information is narrow.
This makes it possible to realize a disk device that does not become worse and the information read / write margin does not deteriorate.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a turntable motor according to one embodiment of the present invention.

2 is a diagram showing the roughness of the peripheral surface of the rotating shaft in FIG. 1 in comparison with the roughness of the peripheral surface of the rotating shaft in FIG. 4;

FIG. 3 is a diagram showing a floppy disk drive in which the turntable motor of FIG. 1 is incorporated.

FIG. 4 is a diagram showing a conventional motor.

[Explanation of symbols]

 Reference Signs List 30 Turntable motor 31 Stator part 32 Rotor part 33 Base 34 Coil 35 Oil-impregnated sintered bearing 36 Rotating shaft made of SUS sintered material 37 Turntable 38 Rotor yoke 39 Rotor magnet 40 Ball bearing 50 Floppy disk device 51 Chassis 52 Cartridge holder 53 Magnetic head 54 Head carriage 55 Carriage moving mechanism 60 Floppy disk 61 Cartridge

Claims (2)

(57) [Claims] The present invention has a stator portion and a rotor portion, the rotor portion having a turntable and a turntable.
A rotating shaft fixed to the center, the stator portion is fixed to the base and the base,
Consists of a sliding bearing that contacts the outer circumference of the rotating shaft
A first bearing, and a second bearing between the base and the turntable.
And the rotating shaft is made of a porous sintered material.
And a motor. 2. A turntable on which a disk is placed.
The turntable motor to be rotated and the motor mounted on the turntable
Thus, a head for reproducing information from a rotating disk
And the turntable motor includes the turntable and the
Having a rotation axis fixed to the center of the turntable.
Data base, a base and the rotating shaft fixed to the base.
Bearing consisting of a plain bearing bearing on the outer periphery of a bearing
And a stator portion having:
A second bearing between the turntable, and
The rotation shaft is made of a porous sintered material.
Disk drive said and.