JPH03189957A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To reduce the thickness of a drive motor by fixing only one end of shaft to a housing, supporting a hub freely rotatably on the shaft via a bearing and housing a magnet and an armature in a recessed part of the hub. CONSTITUTION:One end of the shaft 21 of the drive motor is fixed to the housing 24, where the hub 27 supporting the shaft 21 and a magnetic disk 28 is relatively and freely rotatably fixed. The magnet 32 and the armature 34 are disposed in the recessed part of an annular shape formed in the hub 27, and the magnet 32 is fixed to an inner wall of the hub 27. The housing 24 is arranged with a printed circuit board 29, and the armature coil body 34 is formed by surrounding the magnet 32 and rising from a position opposite to a recessed part 30 of the printed circuit board 29. By this method, the thickness of the drive motor can be reduced.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a magnetic disk device.

(Prior Art) Conventionally, in a magnetic disk device, a plurality of magnetic disks are rotated by a drive motor, and a magnetic head seeks out the magnetic disks to read and write information. .

FIG. 4 is a schematic diagram of a drive motor of a conventional magnetic disk device.

In the figure, ``■'' is a shaft, which is supported by a pair of ball bearings 2 and 3 arranged at a predetermined interval. The ball bearing 2 is fixed above the housing 4, and the ball bearing 3 is fixed below the housing 4. A preload spring 6 is disposed in the axial gap between the poll bearing 3 and the housing 4 by a loose fit, and the preload spring 6 causes both the ball hair rings 2
．． 3. This prevents the occurrence of play in the axial direction.

Further, a hub 7 is fixed to the tip of the shaft 1, and a plurality of magnetic disks 8 are attached to the hub 7 and rotate together with the shaft 1.

On the lower surface of the flange-shaped portion below the housing 4,
A printed circuit board 9 is provided, which carries the necessary circuits to supply current to the windings 11 wound around the stator 10.

Magnello 2 is disposed at a position facing stator 10 fixed to housing 4. The magnetoresistive eye 2 is fixed to a rotor frame 13 rotatably connected to the lower end of the shaft 1, and rotates with the rotation of the rotor 14.

In the drive motor having configuration 1, when current is supplied to the winding 11, the rotor 14 rotates around the shaft 1. This causes the magnetic disk 8 fixed to the tip of the shaft 1 via the hub 7 to rotate.

However, in the magnetic disk drive described above, the drive motor main body portions such as the stator 10 and the magnet 12 are disposed outside the hub 7, resulting in an increase in the size of the drive motor.

Therefore, miniaturized magnetic disk drives have been provided in which drive motors are made thinner.

FIG. 5 is a schematic diagram of a conventional in-hub type drive motor.

In the figure, the stator 1 is attached to the shaft fixed to the housing.
0 is fixed, a ball bearing 2.3 is arranged next to the stator 10 in the axial direction, and the pole bearing 2 is further fixed to the hub 7.

Similar to the example shown in FIG. 4, a winding 11 is disposed on the stator 10, and a magnetic disk 8 is fixed to the hub 7.

Furthermore, recently, the density and capacity of magnetic disks have been increasing, and magnetic disk devices have been provided that can reduce the number of magnetic disks and obtain the same recording capacity.

(Problems to be Solved by the Invention) However, in the magnetic disk device having the configuration described in item 1, the stator 10 and the hair ring 2.3 have a laminated structure, and the magnetic disk device cannot be made thinner.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic disk device that can solve the above problems and make the drive motor thinner.

(Means for Solving the Problems) For this purpose, the present invention fixes one end of the shaft of a drive motor to a housing, and fixes the shaft and a hub that supports a magnetic disk so as to be relatively rotatable. The hub is formed of an annular wall having an n-shaped cross section and opening toward the housing.

Inside the annular recess formed in the hub, there is a magnet.
and an armature, and a magnet is fixed to the inner wall of the hub. On the other hand, the armature is erected from the housing and is provided within the recessed portion to face the magnet.

(Function) According to the present invention, as described above, the shaft of the drive motor is fixed to the housing at only one end, and the hub is rotatably supported by the shaft via the hair ring.

Further, an annular recess is formed in the hub, and a magnet and an armature are disposed in the recess.

When a current flows through the armature, the hub rotatably supported on the shaft rotates.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a drive motor of a magnetic disk device showing an embodiment of the present invention, FIG. 2 is an enlarged view of an armature winding, and FIG. 3 is a sectional view of a hub.

In the figure, 21 is the shaft of the drive motor, and the shaft 2
1 is fixed to the housing 24 at its lower end.

Further, the shaft 21 is supported by a pair of first and second pole bearings 22 and 23 arranged at a predetermined interval. Both ball hair rings 22 and 23 are further supported by a hub 27, and the first pole bearing 22 is placed above the hub 27, and the second pole hair ring 2
3 is fixed below the hub 27.

A preload spring 26 is disposed in the axial gap between the second ball bearing 23 and the hub 27 by a loose fit, and the preload spring 26 causes both ball bearings to
2.23 This prevents the occurrence of axial play.

1. The hub 27 is formed by annularly arranging a wall 33 having an n-shaped cross section and having a recess 30 that opens downward.
A magnet 32 is fixed to the inner wall of 0. On the other hand, a printed circuit board 29 is arranged in the housing 24,
An armature winding body 34 is formed to stand up from a position facing the recess 30 of the printed circuit board 29 and surround the magnet 32.

As shown in FIG. 2, the armature winding body 34 is constructed by disposing coils 36 at several locations in the circumferential direction of an annular cylindrical body 35. The cylinder 35 is made of epoxy resin and is integrally molded with the coil 36.

In FIG. 3, the N-shaped wall 33 has an armature yoke 27b on the inner circumference side and a rotor yoke 27a on the outer circumference side.
have. And the armature yoke 27b
An annular magnet 32 is fixed to.

The magnet 32 is divided into sections, each section forming a north pole and a south pole.

On the other hand, an armature winding body 34 fixed to the housing 24 is arranged to surround the magnet 32, and a plurality of U, V, and W coils 36 are divided and arranged.

Reference numeral 29 denotes a printed circuit board disposed on the surface of the housing 24, on which a circuit necessary for supplying current to each coil 36 of the armature winding body 34 is mounted. Further, 28 is a magnetic disk disposed around the outer periphery of the hub 27.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, only one end of the shaft of the drive motor is fixed to the housing, and the hub is rotatably supported on the shaft via the hair ring.
Moreover, since the magnet and armature are housed in the annular recess formed in the hub, the drive motor can be made thinner.

Furthermore, since it is an outer rotor type and has no slots, there is no coking, making it possible to form a drive motor with low vibration and low noise.

Furthermore, since the rotation is obtained by the magnet and armature, there is no iron loss such as hysteresis loss or eddy current product, and efficiency can be improved.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a drive motor of a magnetic disk device showing an embodiment of the present invention, Fig. 2 is an enlarged view of an armature winding body, Fig. 3 is a cross-sectional view of a hub, and Fig. 4 is a conventional magnetic disk drive motor. A schematic diagram of the drive motor of the device, FIG. 5 is a schematic diagram of a conventional in-hub type drive motor. 1.21...shaft, 4.24...housing, 7.2
7...Hub, 8, 28...Magnetic disk, 22...
- First ball hair ring, 23... Second ball hair ring, 30... Concave portion.

Claims (1)

[Scope of Claims] (a) a shaft having one end fixed to the housing; (b) a hub consisting of an annular wall with an n-shaped cross section that supports a magnetic disk and is open to the housing; (c) A means for relatively rotatably connecting the hub and the shaft;
d) a magnet fixed to an inner wall of an annular recess formed in the hub; and (e) an armature that stands up from the housing and is provided within the recess to face the magnet. magnetic disk device.