JPH05242589A - Magnetic disk assembly - Google Patents

Abstract

PURPOSE:To prevent a good conductor for grounding from generating a noise on account of the friction motion of a friction surface when the good conductor for grounding is worn by the long-term driving of the revolving shaft of magnetic disks and the contact area of the revolving shaft and the good conductor increases. CONSTITUTION:A base plate 6 supports the revolving shaft 2 via ball bearings 3. A spherical surface part 10 is provided at the end of the revolving shaft 2. The good conductor 8 for grounding is pressed by an elastic body 7 to the spherical surface part 10 of the revolving shaft 2. The revolving shaft 2 and the base plate 6 are electrically conducted via the good conductor 8 for grounding. The good conductor 8 for grounding is provided with a cylindrical through- hole centering at the central axis of the revolving shaft 2. The good conductor 8 for grounding and the spherical surface part 10 come into contact with each other in the position apart from the center of rotation and increase the sliding speed. A fluctuation in the speed by friction is thereby suppressed and the generation of the noise is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk assembly, and more particularly to a magnetic disk assembly which requires low noise.

[0002]

2. Description of the Related Art Conventionally, in this type of magnetic disk assembly,
Information is stored concentrically with a fixed width on a disk-shaped magnetic disk, and a magnetic head arranged facing the magnetic disk records and reproduces stored information. The rotating shaft is supported by the base plate via a ball bearing, and the ball bearing is electrically isolated from the base plate during rotation because an oil film of grease is formed. Therefore, a method of electrically connecting the rotary shaft and the base plate with a good conductor for grounding is adopted.

FIG. 4 is a sectional view of a conventional magnetic disk assembly. Further details will be described with reference to this figure. The rotating shaft 2 carries a magnetic disk 1 and is supported by a base plate 6 via a ball bearing 3. The magnetic heads 4 arranged so as to face the magnetic disk 1 are positioned on the magnetic disk 1 by a magnetic head positioning mechanism 5. The base plate 6 contains the magnetic disk 1 and the magnetic head positioning mechanism 5. The rotating shaft 2 is driven by a stator 12 and a rotor 13, and a spherical portion 10 having a shape of a part of an A sphere is provided at an end portion protruding outside the base plate 6.
Is provided. The cover 11 is held by the base plate 6. The elastic body 7 is held by the cover 11 and presses the grounding good conductor 108 against the spherical surface portion 10. The rotating shaft 2 and the base plate 6 are electrically connected to the grounding good conductor 108 through the elastic body 7.

The spherical portion 10 is in contact with the good ground conductor 108 only near the center axis of rotation of the rotary shaft 2. As a result, the sliding speed of the contact portion becomes extremely small, and the spherical good conductor 108 and the spherical surface portion 10 have a higher rigidity than the spherical good portion 108, and the good grounding conductor 108 has a certain degree of freedom with respect to the spherical surface portion 10. In addition, the frictional movement does not become a continuous normal friction phenomenon but becomes an intermittent frictional movement in which adhesion and slip are repeated. When this intermittent frictional movement begins to adhere, the surface having the elastic degree of freedom is compressed with time, and the elastic force increases as a shearing force. When this elastic force acts as a shearing force and becomes larger than the bonding force of the adhesion between the two surfaces, slippage occurs and the amount of bending of the elastic surface becomes small. In this case, the elastic surface is elastically vibrating. When the relative velocity between the friction lower surface and the friction upper surface of the contact surface becomes 0 due to elastic vibration, the adhesion starts again. This movement may be repeated as a cycle with a constant frequency.

[0005]

In the above-described conventional magnetic disk assembly, the contact area between the good earth conductor and the spherical portion near the center of rotation is abraded by the good earth conductor due to long-term driving of the rotating shaft. Has a drawback that a specific frictional movement occurs and noise is generated.

[0006]

SUMMARY OF THE INVENTION A magnetic disk assembly of the present invention is a magnetic disk for magnetic recording, a rotary shaft for mounting and rotating the magnetic disk, a ball bearing for supporting the rotary shaft, and the ball. A base plate that holds a bearing and contains the magnetic disk, and a spherical through hole that has a cylindrical through hole centered on the central axis of the rotary shaft and is provided along the inner edge of the through hole at the end of the rotary shaft. A good grounding conductor that is in contact with the base plate and is pressed from the base plate through the elastic body to the spherical surface part.

[0007]

The present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention.
Similar to the conventional example shown in FIG. 4, the rotary shaft 2 carries the magnetic disk 1 and is supported by the base plate 6 via the ball bearings 3. A magnetic head 4 arranged so as to face the magnetic disk 1 is positioned on the magnetic disk 1 by a magnetic head positioning mechanism 5. The base plate 6 contains the magnetic disk 1 and the magnetic head positioning mechanism 5.
The rotating shaft 2 is driven by the stator 12 and the rotor 13, and the spherical portion 1 is provided on the end protruding outside the base plate 6.
0 is provided. The cover 11 is held by the base plate 6. The elastic body 7 is held by the cover 11,
The good conductor 8 for earth is pressed against the spherical surface portion 10. The rotating shaft 2 and the base plate 6 are electrically connected to each other through a good conductor 8 for grounding and an elastic body 7. 4 is different from the conventional example in FIG. 4 in that the grounding good conductor 8 is provided with a cylindrical through hole 9 centered on the central axis of the rotating shaft 2 and the tip of the spherical portion 10 is provided in this through hole 9. It is inset.

FIG. 2 is an enlarged view of the vicinity of the contact portion 16 between the grounding good conductor 8 and the spherical surface portion 10 when the elastic body 7 is the leaf spring 14. The leaf spring 14 is held by the cover 11 and presses the good earth conductor 8 against the spherical surface portion 10. The rotary shaft 2 and the base plate 6 are electrically connected to each other through a good grounding conductor 8 and a leaf spring 14.

FIG. 3 shows a contact portion 16 between the good conductor 8 for grounding and the spherical portion 10 when the elastic body 7 is a compression coil spring 15.
It is an enlarged view of the vicinity. The compression coil spring 15 covers the cover 11.
The good conductor 8 for earth is pressed against the spherical surface portion 10. The rotary shaft 2 and the base plate 6 are electrically connected to each other through a grounding good conductor 8 and a compression coil spring 15.

Next, the function of reducing noise when the magnetic disk rotates will be described. The good conductor 8 for grounding and the spherical surface portion 10 are on the contact circle 1 on the outer circumference circle of the through hole 9 and apart from the central axis of the rotating shaft 2.
Contacted at 6. The rotating peripheral speed of the contact portion 16 is the rotating shaft 2
Since it is distant from the central axis of, the rotational peripheral speed near the central axis of the rotary shaft 2 becomes faster. As the rotational peripheral speed of the contact portion 16 becomes faster, the sliding speed at the contact surface of the contact portion 16 becomes faster and the static friction coefficient becomes smaller. When the static friction coefficient becomes smaller, the difference between the static friction coefficient and the dynamic friction coefficient becomes smaller, so that the amount of deflection of the elastic surface becomes smaller in one cycle. When the slip velocity reaches a certain critical friction velocity, the difference between the static friction coefficient and the dynamic friction coefficient becomes extremely small, and temporary adhesion does not occur. When the normal conductor 8 for grounding and the spherical surface portion 10 have continuous normal frictional movements without temporarily adhering to each other on the contact surface of the contact portion 16, intermittent friction that repeats adhesion and sliding between the good conductor for earthing 8 and the spherical surface portion 10 is performed. Movement cannot occur. When the intermittent friction motion stops,
Elastic vibration does not occur on the elastic surface, and noise is suppressed.

[0012]

As described above, according to the present invention, the contact point of the good conductor for grounding for electrical connection with the rotating shaft of the magnetic disk is located away from the center of rotation to increase the sliding speed, and thus the rotating shaft. It is possible to prevent the generation of noise by suppressing the elastic vibration of the good conductor for grounding caused by the abrasion due to the long-term driving. Further, there is an effect that an environmental problem due to noise is improved and a highly reliable magnetic disk assembly can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetic disk assembly showing an embodiment of the present invention.

FIG. 2 is an enlarged view of the vicinity of a good ground conductor when the elastic body of FIG. 1 is composed of a leaf spring.

FIG. 3 is an enlarged view of the vicinity of a good conductor for ground when the elastic body of FIG. 1 is composed of a compression coil spring.

FIG. 4 is a sectional view of a conventional magnetic disk assembly.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 magnetic disk 2 rotating shaft 3 ball bearing 4 magnetic head 5 magnetic head positioning mechanism 6 base plate 7 elastic body 8,108 good conductor for earth 9 through hole 10 spherical surface 11 cover 12 stator 13 rotor 14 leaf spring 15 compression coil spring 16 contact portion

Claims (1)

[Claims] 1. A magnetic disk for magnetic recording, a rotating shaft for mounting and rotating the magnetic disk, a ball bearing for supporting the rotating shaft, and a base plate for holding the ball bearing and enclosing the magnetic disk.
There is a cylindrical through hole centering on the central axis of the rotating shaft and is in contact with a spherical portion provided at the end of the rotating shaft along the inner edge of the through hole, and an elastic body is removed from the base plate. A magnetic disk assembly, comprising: a good grounding conductor pressed against the spherical surface through the magnetic disk assembly.