JP2705384B2 - Magnetic disk assembly - 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 assembly, and more particularly, to noise generated when a magnetic disk rotates.

[0002]

2. Description of the Related Art In a magnetic disk assembly, information is stored concentrically with a constant width on a disk-shaped magnetic disk, and a magnetic head arranged opposite to the magnetic disk records and reproduces information. Is going. The rotating shaft on which the magnetic disk is mounted is supported by a base plate via a ball bearing, and is electrically isolated from the base plate because a grease oil film is formed on the ball bearing during rotation. For this reason, a method has been adopted in which the rotary shaft and the base plate are electrically connected by a good conductor for grounding.
Details of the above configuration will be described with reference to the drawings.

FIG. 3A is a sectional view of a conventional magnetic disk assembly. In the conventional example shown in FIG. 3A, the rotating shaft 2 has a magnetic disk 1 mounted thereon and is supported by a base plate 6 via a ball bearing 3. The magnetic head 4 arranged 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 a stator 11 and a rotor 12, and a spherical portion 9 is provided at an end protruding outside the base plate 6. The cover 10 is held on the base plate 6. The elastic body 7 is the cover 1
0, and presses the grounding good conductor 8 against the spherical portion 9. The rotating shaft 2 and the base plate 6 are electrically connected to each other via the good earth conductor 8 and the elastic body 7.

FIG. 3B shows a good conductor 8 for grounding and a spherical portion 9.
It is an enlarged view near the contact part with. A vertical line 14 at a contact portion 13b which is a contact point between the good earth conductor 8 and the spherical portion 9
And the shaft center line 15 of the rotating shaft 2 is extremely adjacent. That is, the contact portion 13b exists at a position very close to the axis center line 15.

[0005] Therefore, the sliding speed of the contact portion 13 b is extremely low, and the spherical portion 9 has higher rigidity between the good grounding conductor 8 and the spherical portion 9 and the good grounding conductor 8 has a certain degree with respect to the spherical portion 9. To have freedom,
The frictional motion does not become a continuous normal frictional phenomenon but an intermittent frictional motion in which adhesion and slipping are repeated. When the intermittent friction motion starts to adhere, the surface having the elastic degree of freedom is compressed with time, and the elastic force increases as a shear force. When this elastic force acts as a shear force and becomes larger than the bonding force of the adhesion between the two surfaces, slip occurs, and the amount of deflection of the elastic surface decreases. In this case, the elastic surface is performing elastic vibration. Adhesion starts again when the relative speed between the friction lower surface and the friction upper surface of the contact surface becomes zero due to the elastic vibration. In some cases, this movement is repeated at a constant frequency with one cycle as the movement.

[0006]

In the above-mentioned conventional magnetic disk assembly, since the good conductor for ground rubs due to the long-term driving of the rotating shaft, the contact area near the center of rotation between the good conductor for ground and the spherical portion is reduced. The above-mentioned intermittent frictional motion occurs, and there is a drawback that noise is generated.

[0007]

According to the present invention, there is provided a magnetic disk assembly comprising: a magnetic disk; a rotating shaft on which the magnetic disk is mounted; a ball bearing for supporting the rotating shaft;
A magnet having a base plate holding the ball bearing and enclosing the magnetic disk, a spherical body provided at an end of the rotating shaft, and a good grounding conductor pressed against the spherical portion from the base plate via an elastic body. In the disk assembly, the good grounding conductor and the spherical portion are brought into contact with each other at a position away from the axis of the rotating shaft.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1A is a sectional view of one embodiment of the present invention.

In the embodiment shown in FIG. 1A, the rotating shaft 2 has a magnetic disk 1 mounted thereon and is supported by a base plate 6 via a ball bearing 3. The magnetic disk 4 arranged to face the magnetic disk 1 is positioned on the magnetic disk 1 by the 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 11 and a rotor 12, and a spherical portion 9 is provided at an end protruding outside the base plate 6. The cover 10 is held on the base plate 6. The elastic body 7 is the cover 1
0, and presses the grounding good conductor 8 against the spherical portion 9. The vertical line 14 at the contact portion between the good earth conductor 8 and the spherical portion 9 has an angle 16 with respect to the axis center line 15. In other words, the position of the contact portion is away from the axis center line 15.

FIG. 1B is an enlarged view of the vicinity of a contact portion between the good earth conductor 8 and the spherical portion 9 when the elastic body 7 is a leaf spring 17. The leaf spring 17 is held by the cover 10. A vertical line 14 at a contact portion 13a, which is a contact point between the good earth conductor 8 and the spherical portion 9, is formed by an axis center line 15
The good conductor 8 for grounding is provided so as to have an angle 16 with respect to. The grounding good conductor 8 is pressed against the spherical portion 9 by a leaf spring 17. The rotating shaft 2 and the base plate 6 are electrically connected to each other via the good ground conductor 8 and the leaf spring 17.

FIG. 2 is an enlarged view of the vicinity of the contact portion between the good earth conductor 8 and the spherical portion 9 when the elastic body 7 is a compression coil spring 18. The compression coil spring 18 is held by the cover 10a. The good ground conductor 8 is provided so that a vertical line 14 at a contact portion 13 a, which is a contact point between the good ground conductor 8 and the spherical portion 9, has an angle 16 with respect to the axis 15 of the rotating shaft 2. The good conductor for ground 8 is pressed against the spherical portion 9 by a compression coil spring 18. The rotating shaft 2 and the base plate 6 are made of a good earth conductor 8 and a compression coil spring 1.
8 electrically.

In FIG. 1B or FIG. 2, the good earth conductor 8 and the spherical portion 9 are in contact with each other at a contact portion 13a where the vertical line 14 and the axial center line 15 have an angle 16. Since the contact portion 13a is apart from the central axis of the rotating shaft 2, the rotational peripheral speed of the contact portion 13a becomes faster than the rotational peripheral speed near the central axis of the rotating shaft 2. As the rotational peripheral speed of the contact portion 13a increases, the slip speed on the contact surface of the contact portion 13a increases.
When the sliding speed at the contact surface of the contact portion 13a increases, the coefficient of static friction at the contact surface of the contact portion 13a decreases. When the coefficient of static friction decreases, the difference between the coefficient of static friction and the coefficient of dynamic friction decreases, so that the amount of the periodic elastic surface deflection decreases. When the slip velocity reaches a certain critical friction coefficient velocity, the difference between the static friction coefficient and the dynamic friction coefficient becomes extremely small, so that there is no temporary adhesion. When the good conductor 8 for grounding and the spherical portion 9 are in continuous normal frictional motion without being temporarily attached to the contact surface of the contact portion 13a, the good conductor 8 for grounding is used.
The intermittent frictional motion that repeats adhesion and sliding between the and the spherical portion 9 cannot be generated. When the intermittent friction motion does not occur, no elastic vibration occurs on the elastic surface.

[0014]

As described above, by using the present invention for a magnetic disk assembly, elastic vibration of a good earth conductor caused by abrasion due to long-term driving of a rotating shaft is suppressed, thereby preventing generation of noise. be able to. 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 the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing an embodiment of the present invention. FIG. 1 (A) is a cross-sectional view, and FIG. 1 (B) is an enlarged view near a grounding good conductor 8 when an elastic body 7 is used as a leaf spring. It is.

FIG. 2 is an enlarged view of the vicinity of a grounding good conductor 8 when the elastic body 7 in FIG. 1A is used as a compression coil spring.

FIG. 3 is a view showing a conventional magnetic disk assembly;
(A) is a sectional view, and (B) is an enlarged view near the good conductor 8 for grounding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic disk 2 Rotating shaft 3 Ball bearing 6 Base plate 7 Elastic body 8 Good conductor for ground 9 Spherical part 10, 10a Cover 13a, b Contact part 14 Vertical line 15 Axis center line 16 Angle 17 Leaf spring 18 Compression coil spring

Claims (1)

(57) [Claims] 1. A magnetic disk, a rotating shaft on which the magnetic disk is mounted, a ball bearing for supporting the rotating shaft, a base plate for holding the ball bearing and containing the magnetic disk, and an end of the rotating shaft. In the magnetic disk assembly having a spherical body provided on the base plate and a grounding good conductor pressed from the base plate to the spherical part via an elastic body, the good grounding conductor and the spherical part are axially centered on the rotation axis. A magnetic disk assembly, wherein the magnetic disk assembly is brought into contact at a position away from the line.