JPH05334663A - Magnetic disk - Google Patents

Abstract

PURPOSE:To eliminate the pressure difference between the air layer provided between a magnetic sheet and a substrate and the outdoor air regardless of a change in the external moisture and temp. and to extend the magnetic sheet uniformly over the entire circumference, and to eliminate the pressure difference of even the magnetic disk of a double sided type extended with the magnetic sheets 6 on both surfaces of a rigid substrate. CONSTITUTION:This magnetic disk is constituted by extending the magnetic sheets on the disk-shaped rigid substrate 2 having respectively circular projecting parts 5, 6 along its outer peripheral edge and inner peripheral edge with the projecting parts 5, 6 of the above-mentioned outer peripheral edge and inner peripheral edge as adhesive surfaces. The projecting part 6 of the outer peripheral edge is made into double structures. The projecting part 6a on the inner peripheral side and the projecting part 6b on the outer peripheral side are provided with notched parts. 9a, 9b. These notched parts are so disposed as not to line up in the diametral direction of the disk. The notched parts may be provided not only in the projecting part 6 of the outer peripheral edge but in the projecting part 5 on the inner peripheral edge as well or may be provided in either thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk in which a flexible magnetic sheet is stretched in a so-called drum-like state on the surface of a disc-shaped rigid substrate.

[0002]

2. Description of the Related Art For example, a magnetic disk system using a flexible magnetic recording medium is widely used as a floppy disk, a Mabika, etc., and both track density and linear density are high in order to further reduce the size and increase the capacity. It is in the direction of becoming. At this time, since a base film made of a polymer material is used as the magnetic recording medium, the influence of expansion and contraction of the magnetic recording medium due to changes in temperature and humidity becomes significant. Therefore, a magnetic disk having the features of both a hard disk and a floppy disk, that is, a flexible film-shaped magnetic recording medium is attached to a convex portion of a highly rigid disk-shaped substrate with its outer and inner edges raised Fixed magnetic disks have been developed.

In such a magnetic disk, since the film-shaped magnetic recording medium is stretched and supported by the rigid substrate, the recording area in contact with the magnetic head becomes a uniform surface and the magnetic head also contacts. A good head contact can be obtained because the recording area becomes an air layer.
Therefore, this magnetic disk is superior to a hard disk, a floppy disk, or the like in that the magnetic head collides with the rigid substrate and the pressure pad is unnecessary.

By the way, in the above magnetic disk,
Since the film-shaped magnetic recording medium is held against the rigid substrate with uniform tension, it is necessary to prevent a pressure difference between the air layer provided between the medium and the substrate and the outside air. As a means for this, for example, by providing a small circular vent hole penetrating the plate thickness of the rigid substrate between the convex portions provided on the outer peripheral edge and the inner peripheral edge, the pressure difference between the air layer between the medium and the substrate and the external air is provided. There is a method of eliminating.

However, if the rigid substrate is formed with a vent hole penetrating the plate thickness, only one side of the magnetic disk can be used, which is not suitable for high recording density which will be required more and more in the future. In addition, it is conceivable to provide a small ventilation hole in the magnetic recording medium itself, but since the medium is attached to the rigid substrate with tension, the medium is liable to break,
Unreliable.

[0006]

Therefore, the present invention has been proposed in view of such circumstances, and eliminates the pressure difference between the air layer between the medium and the substrate and the outside air, and obtains a good head contact. At the same time, it is an object of the present invention to provide a magnetic disk that can sufficiently support high density recording.

[0007]

The present invention has been proposed to achieve the above object. That is, a magnetic recording medium is formed by tensioning a film-shaped magnetic recording medium on a disc-shaped rigid substrate having annular convex portions along the outer peripheral edge and the inner peripheral edge, respectively, with the convex portions of the outer peripheral edge and the inner peripheral edge serving as adhesive surfaces. In the disc, at least one of the convex portions on the outer peripheral edge or the inner peripheral edge has a concentric double structure, and notches are formed in the convex portion on the outer peripheral side and the convex portion on the inner peripheral side, respectively. It is characterized in that the notch portions are arranged so as not to be aligned in the radial direction of the disc.

[0008]

In the magnetic disk of the present invention, since the notch is provided on at least one of the outer peripheral edge and the inner peripheral edge of the rigid substrate, the notch functions as a ventilation hole, and the outer peripheral edge The pressure of the air layer existing between the film-shaped magnetic recording medium stretched between the convex portion and the convex portion of the inner peripheral edge and the rigid substrate and the outside air are kept equal.

Further, the convex portions on the outer peripheral edge or the inner peripheral edge have a concentric double structure, and the notch portions provided on the convex portion on the outer peripheral side and the convex portion on the inner peripheral side are arranged in the radial direction of the disk. By arranging the film-shaped magnetic recording medium so that it does not exist, the film-shaped magnetic recording medium is apparently adhered over the entire circumference of the rigid substrate. That is, even if the film-shaped magnetic recording medium is not adhered to the cutout portion formed in one of the convex portions having the double structure, the same radius of the position where the cutout portion is provided is provided. Bonding is performed at the other convex portion. Therefore, the tension of the film-shaped magnetic recording medium is stretched substantially uniformly over the entire circumference of the rigid substrate.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described in detail below with reference to the drawings. In the magnetic disk 1 of this embodiment, as shown in FIG. 1, a flexible film-shaped magnetic recording medium (hereinafter referred to as a magnetic sheet 3) is fixed to a rigid substrate 2 having a disk shape. It is stretched in a so-called taiko-drum state with the tension of.

Since the magnetic sheet 3 is stretched on the rigid substrate 2 with a constant tension, the material of the rigid substrate 2 is a material having a low coefficient of thermal expansion that is not easily affected by changes in humidity and temperature. It is required to be made of a highly rigid material. For example, a metal such as aluminum or stainless steel, a plastic, or the like can be used, and a molded body of these is suitable.

At the center of the rigid substrate 2, there is provided a center hole 4 into which a positioning protrusion of a turntable attached to the tip of a spindle motor provided in the magnetic recording / reproducing apparatus is inserted and engaged. The positioning protrusion of the turntable is inserted into the center hole 4, and the magnetic disk 1 is positioned on the turntable 4 by engaging the protrusion with the inner wall surface of the center hole 4.

Then, as shown in FIG.
On one surface, a convex portion 5 along the inner peripheral edge and a convex portion 6 along the outer peripheral edge, which serve as an adhesive portion for adhesively fixing the magnetic sheet 3, are provided. The protrusions 5 and 6 are respectively formed as annular protrusions having a rectangular cross section, and the upper surfaces thereof are adhesive surfaces for adhesively fixing the magnetic sheet 3. Therefore, the widths of the upper surfaces of the projections 5 and 6 are at least wide enough to securely bond and fix the magnetic sheet 3.

When the rigid substrate 2 is viewed in the opposite way, a wide and relatively shallow annular groove 7 is provided between the inner peripheral edge convex portion 5 and the outer peripheral edge convex portion 6. Will be Since the concave groove 7 is closed by the magnetic sheet 3 stretched over the convex portions 5 and 6 of the rigid substrate 2, an air layer 8 is formed in the gap between the magnetic sheet 3 and the concave groove 7. Become. The air layer 8 serves as an escape groove that secures a good contact with the magnetic head and that alleviates an accidental collision of the head. That is, even if the magnetic head carelessly contacts the magnetic sheet 3 with a strong force, the magnetic head does not contact the rigid substrate 2.

In this magnetic disk, among the projections 5 and 6 provided on the rigid substrate 2, the projections 6 along the outer peripheral edge are the concentric circular projections 6a on the inner peripheral side and the outer peripheral side. It has a double structure composed of the convex portions 6b. And
From the opposite viewpoint of the rigid substrate 2 in the vicinity of the convex portion 6 along the outer peripheral edge, between the inner peripheral convex portion 6a and the outer peripheral convex portion 6b, a small annular concave portion is formed. The groove 10 will be provided.

The inner peripheral side convex portion 6a and the outer peripheral side convex portion 6
in b, as shown in FIG. 3, the circumferential width W _1, W ₂ is a cut-away portion 9a, 9b is provided. These cutouts 9a and 9b function as ventilation holes for eliminating the pressure difference between the air layer 8 existing between the magnetic sheet 3 and the concave groove 8 and the outside air due to the change in the external humidity temperature. The notch 9a provided on the inner peripheral side convex portion is formed outward from the concave groove 7 (outer peripheral side convex portion 6b side) at substantially the same position as the bottom surface of the concave groove 7. It On the other hand, the convex portion 6 on the outer peripheral side
The notch 9b provided in b is formed at the substantially same position on the bottom surface of the groove 10 and outward from the groove 10. Therefore, the air layer 8 in the gap between the magnetic sheet 3 and the concave groove 7 communicates with the outside air through the cutout portion 9a, the concave groove 10, and the cutout portion 9b. As a result, as shown in FIG. 4, the air in the air layer 8 is removed from the notch 9
It flows out into the atmosphere via a, the groove 10, and the notch 9b. As a result, the pressure difference between the air layer 8 and the outside air is made equal.

Here, the cutout portions 9a and 9b are not arranged on the same radius of the rigid substrate 2, but are provided in a staggered manner. As a result, when the magnetic sheet 3 is bonded to the rigid substrate 2, the magnetic sheet 3 has the convex portion 6
In a, even if the notch 9a is not adhered, it is adhered on the convex portion 6b on the outer peripheral side located on the same radius, and conversely, if the notch 9b is not adhered, the same radius is obtained. It is adhered on the convex portion 6a on the inner peripheral side located above.

Therefore, the width W of each notch 9a, 9b
_{Even if 1} and W ₂ are made relatively wide, the tension of the magnetic sheet 3 is kept uniform. In addition, these notches 9a and 9b
The widths W ₁ and W ₂ of the magnetic sheet 3 may be such that the air in the air layer 8 can pass through sufficiently.
In order to prevent the cutouts 9a and 9b from being blocked by the adhesive used when the is bonded to the rigid substrate 2, it may be widened to some extent.

On the other hand, the magnetic sheet 3 is formed by forming a magnetic layer on the surface of a flexible base film such as a polyethylene terephthalate film or a polyimide film. The magnetic layer used here is
It is not particularly limited, and may be one obtained by dispersing and coating a magnetic powder such as a ferromagnetic oxide powder such as γ-Fe ₂ O ₃ or a ferromagnetic metal powder such as Fe. A ferromagnetic metal magnetic material such as a Co—Ni alloy may be deposited by a vacuum thin film forming technique such as vapor deposition or sputtering. If necessary, a protective film layer, a lubricant layer, etc. may be formed on the magnetic layer. The magnetic sheet 3 is pressed against the convex portions 5, 6 and 7 of the rigid substrate 2 to which the adhesive is applied with a predetermined tension applied by a pair of donut-shaped rings, and then dried. The rigid substrate 2 is stretched with respect to the rigid substrate 2 by being cut along the outermost peripheral surface of the rigid substrate 2 with a knife or the like.

The cutouts 9a and 9b as the vent holes as described above may be provided not only on the convex portion 6 along the outer peripheral edge but also on the convex portion 5 along the inner peripheral edge, or It may be provided in either of them. However, when provided only on the convex portion 5 along the inner peripheral edge, the convex portion 5 needs to have a double structure like the convex portion 6 in the present embodiment.

[0021]

As is apparent from the above description, in the magnetic disk of the present invention, since at least one of the outer peripheral edge and the inner peripheral edge of the rigid substrate is provided with a notch portion functioning as a ventilation hole, The pressure difference between the air layer existing between the magnetic sheet stretched between these convex portions and the rigid substrate and the outside air disappears. Therefore, the tension of the magnetic sheet can be kept constant without being affected by the external wet temperature, and a good head contact of the magnetic head can be secured.

Further, since the air holes are provided in the convex portion which is provided one step higher than the main surface of the rigid substrate, the magnetic sheet is not broken as in the conventional case where the air holes are formed in the magnetic sheet itself. There is no fear, and it can also be applied to a double-sided magnetic disk in which magnetic sheets are stretched on both sides of a rigid substrate. Further, in the magnetic disk of the present invention, at least one of the protrusions on the outer peripheral edge or the inner peripheral edge has a concentric double structure, and cuts provided on the outer peripheral side convex portion and the inner peripheral side convex portion, respectively. Since the notches are arranged so that they are not aligned in the radial direction, the magnetic sheet adheres to the rigid substrate over the entire circumference, and even if the width of this notch is increased to some extent, the tension of the magnetic sheet It is possible to prevent unevenness.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a magnetic disk to which the present invention is applied.

FIG. 2 is a sectional view showing the structure of a magnetic disk to which the present invention is applied.

FIG. 3 is a perspective view showing a structure of a rigid substrate of a magnetic disk to which the present invention is applied.

FIG. 4 is an enlarged plan view for explaining the flow of air that flows out through a notch provided in a convex portion along the outer peripheral edge of the rigid substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Magnetic disk 2 ... Rigid substrate 3 ... Magnetic sheet (film-shaped magnetic recording medium) 4 ... Center hole 5 ... Inner peripheral edge convex portion 6 ... Outer peripheral edge convex portion 6a ... Convex portion on the inner peripheral side 6b ... Convex portion on the outer peripheral side 7,10 ... Concave groove 8 ... Air layers 9a, 9b ... Notched portion

Claims (1)

[Claims] 1. A film-shaped magnetic recording medium is stretched on a disc-shaped rigid substrate having annular protrusions along the outer peripheral edge and the inner peripheral edge, with the convex portions on the outer peripheral edge and the inner peripheral edge serving as adhesive surfaces. At least one of the convex portions on the outer peripheral edge or the inner peripheral edge has a concentric double structure, and notches are formed on the convex portion on the outer peripheral side and the convex portion on the inner peripheral side. The magnetic disk is characterized in that the notches are arranged so as not to be aligned in the radial direction of the disk.