JP2568953Y2 - Magnetic disk drive - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive for mounting and rotating a magnetic disk such as a hard disk.

[0002]

2. Description of the Related Art A configuration as shown in FIG. 2 has been proposed as a magnetic disk drive. In FIG. 2, frame 1
Has a large-diameter portion 2 integrally formed at the center portion thereof, and a shaft portion 3 is integrally provided above the large-diameter portion 2. Inner rings of a pair of upper and lower ball bearings 4 and 5 are fitted and fixed to the outer periphery of the shaft portion 3, and the outer rings of the ball bearings 4 and 5 are inserted into the inner diameter of the hub 6, thereby rotating the hub. It is freely supported. The outer peripheral portions of the shield plates 4a, 5a for sealing are fixed to the upper and lower ends of the outer rings of the ball bearings 4, 5, and the inner peripheral portions of the shield plates 4a, 5a extend to the inner ring side, and a slight gap is formed. At the inner ring.

The hub 6 is used to integrally hold and rotate a magnetic disk such as a hard disk (not shown), and is formed in a substantially bell shape, and has a step portion for mounting the magnetic disk on an outer diameter portion. 6a. further,
The lower portion of the step 6a of the hub 6 is integrally formed in a cylindrical shape having an outer diameter larger than the outer diameter portion, and is located inside the dish-shaped portion and on the inner peripheral surface below the step 6a. A cylindrical drive magnet 8 is fixed via an annular yoke 7 to form a rotor portion of the motor.

[0004] A labyrinth seal portion 9 is formed between the outer periphery of the dish-shaped portion and the inner surface of the frame 1 at a small interval. The labyrinth seal portion 9 prevents dust such as oil mist generated from the ball bearings 4 and 5 from scattering to the outer diameter portion of the hub 6. A cylindrical rotor magnet 8 is fitted and fixed to the inner peripheral side of the hub 5 to form a rotor portion.

On the other hand, an armature core 10 is fitted and fixed to the outer periphery of the large diameter portion 2. The armature core 9 has a plurality of radially formed salient poles, and a coil 11 is wound on each of the salient poles, for example, in a three-phase form. The outer peripheral surface of the armature core 10 faces the inner peripheral surface of the drive magnet 8 with a gap. A motor section is constituted by the armature core 9 and the driving magnet 8 and the like. The motor section is provided inside the frame 1 and the hub 6 is integrally rotated by urging the driving magnet 8 to rotate.

Further, a magnetic fluid seal mechanism 12 for preventing dust such as oil mist from the ball bearings 4 and 5 from scattering from the upper end side of the hub 6 to the outside is provided at the upper end of the hub 6. Have been. Since the frame 1 is generally formed integrally with the shaft 3 from a non-magnetic metal made of aluminum, a portion of the upper end of the shaft 3 corresponding to the magnetic fluid seal mechanism 12 is required to make the magnetic fluid seal mechanism 12 function effectively. Ring 13 made of magnetic metal
Are fitted and fixed.

[0007]

In the magnetic disk drive described above, a pair of upper and lower ball bearings 4, 5 in which the inner ring is fitted and fixed to the outer periphery of the shaft 3, respectively, are sealed at the upper and lower ends of the outer ring. Since the stopping shield plates 4a and 5a are provided, the axial dimension t1 of the ball bearing itself is inevitably increased. As a result, the span length L1 of the ball bearings 4 and 5 becomes shorter, so that the hub 6
The resonance frequency of the magnetic disk portion (not shown) mounted on the outer peripheral surface of the disk becomes lower. As a result, there is a problem that when vibration is given in a state where the magnetic disk drive device is incorporated in a hard disk drive device, the magnetic disk portion resonates and adversely affects read / write characteristics. Further, when the span length L1 of the ball bearings 4 and 5 is short, there is a problem that the runout of the outer peripheral portion of the hub 6 becomes large and the rotational accuracy is reduced.

The present invention has been made to solve such a problem. The resonance frequency is increased by a simple configuration to reduce the read / write error of the magnetic disk, and the rotation accuracy of the hub is increased. It is an object of the present invention to provide a magnetic disk drive capable of performing the following.

[0009]

According to the present invention, a large-diameter portion and a shaft portion are continuously provided from a center portion of a frame, and a stator portion of a motor is disposed around the large-diameter portion. In a magnetic disk drive device in which a hub is rotatably supported via a pair of ball bearings with a shield plate, the pair of ball bearings are formed flat only by providing the shield plates only on one end face located outside each other. These ball bearings are fitted and fixed to both ends of the shaft part at a distance from each other, and are placed on the flat surface of the step from the large diameter part to the shaft part.
The ball bearing on the large diameter side of the ball bearing
The above-mentioned shield plate of the ring is closely opposed .

[0010]

The shield plates of a pair of ball bearings are provided only on one end face located outside each other, and are formed flat.
When these ball bearings are fitted and fixed to both ends of the shaft portion while being separated from each other, the span length between the ball bearings increases, so that the resonance frequency of the hub can be increased. As a result, even when vibration is applied from the outside, resonance of the hub and the magnetic disk is reduced, and read / write errors of the magnetic disk can be reduced. Further, when the span length between the pair of ball bearings is increased, the hub is supported at both ends, and the rotation accuracy of the hub is increased. Ma
Also, close to the plane of the step even if the inner shield plate is eliminated
Since the outer shield plate is placed facing
The dust generated in the bearing can be shut off.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic disk drive according to the present invention will be described below with reference to the drawings. 2 denote the same parts, and a detailed description thereof will be omitted. In FIG. 1, a pair of ball bearings 20, 21
By providing the shielding plates 20a, 21a for sealing only on one end face located outside each other, the axial dimension t2 is reduced and the whole is formed in a flat shape.
Each of the shield plates 20a and 21a has an outer peripheral portion fixed to the outer ring, and the inner peripheral portion extends toward the inner ring side and faces the inner ring with a slight gap.

The pair of flat ball bearings 20 and 21 are spaced apart from both ends of a shaft 3 integrally connected to a large diameter portion 2 integrally formed at the center of the frame 1. Fitted and fixed. Incidentally, it is desirable that the distance between the ball bearings 20 and 21 is set to be equal to or greater than the axial dimension t2 of the ball bearing.

On the other hand, a shield plate 20a provided on the lower ball bearing 20 is closely opposed to a flat surface of a step portion from the large diameter portion 2 to the small diameter shaft portion 3 of the frame 1 with a small gap. With this configuration, the outer ring of the ball bearing 20 rotates at a high speed together with the hub 6,
An air flow is generated in the gap to generate a kind of air curtain effect, and dust such as oil mist in the ball bearing is shut off.

The dust shielding effect is also provided by the shield plate 21a of the upper ball bearing 21, but a magnetic fluid seal mechanism 12 is provided on the upper end side of the hub 6 for further perfection. ing. Since the frame 1 in this embodiment is made of a magnetic material such as iron, the inner peripheral side of the magnetic fluid sealing mechanism 12 is directly opposed to the upper end of the shaft 3.

With the above configuration, the ball bearing 2
The span length L2 between 0 and 21 is significantly longer than the span length L1 of FIG. As described above, when the span length L2 is increased and the hub 6 is supported by being fitted and fixed to both ends of the shaft portion 3, the resonance frequency of the outer peripheral portion of the hub 6 can be increased. Therefore, even if vibration is applied in a state where the magnetic disk drive device is incorporated in the hard disk drive device, the magnetic disk portion does not resonate,
Good read / write characteristics are obtained. Further, in the above embodiment, since the span length L2 between the ball bearings 20 and 21 is set substantially equal to the axial dimension of the hub 6, the run-out of the hub 6 is greatly suppressed, and the rotation of the hub 6 is reduced. The accuracy will be kept high.

The above-described embodiment shows an example of the present invention, and the shapes of the respective parts such as the hub and the frame may be changed in other ways, and various changes can be made without departing from the present invention.

[0017]

As is apparent from the above description, the magnetic disk drive of the present invention has a flat structure in which the shield plates of the pair of ball bearings are provided only on one end face located outside each other and are flat. Since these ball bearings are fitted and fixed at both ends with a space between them, the span length between the ball bearings can be increased, so that the resonance frequency of the hub can be increased. Write errors can be reduced. Further, because possible to increase the span length, next it can support the hub at both ends, there is the advantage that it is possible to improve the rotational accuracy of the hub. Furthermore, the inside shield plate is eliminated.
Dust in each ball bearing is discharged to the outside by
However, the flat surface of the step from the large diameter part to the shaft part
Because the two shield plates are close to each other, the dust
The discharge to the motor unit can be blocked.

[0018]

[Brief description of the drawings]

FIG. 1 is a half sectional view showing an embodiment of a magnetic disk drive according to the present invention.

FIG. 2 is a sectional view showing a conventional magnetic disk drive.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Frame 2 Large diameter part 3 Shaft part 6 Hub 10 Armature core (stator) 20,21 Ball bearing 20a, 21a Shield plate

Claims (1)

(57) [Scope of request for utility model registration] 1. A large diameter portion and a shaft portion are continuously provided from a center portion of a frame, a stator portion of a motor is provided around the large diameter portion, and a ball with a pair of shield plates is provided on the shaft portion. In a magnetic disk drive device in which a hub is rotatably supported via a bearing, the pair of ball bearings are formed flat by providing the shield plates only on one end surface located outside each other, and are formed flat at both ends of the shaft portion. apart from these ball bearings were fitted and fixed, the above-mentioned from the large-diameter portion
The top of the above ball bearing
Close the shield plate of the ball bearing on the large diameter side
A magnetic disk drive device that faces each other.