JPH01140481A - Magnetic disk - Google Patents

Abstract

PURPOSE:To enlarge a magnetic disk using area by providing the bank part of a magnetic paint in the peripheral part of an aluminum substrate and thereby eliminating a protrusion part by the bank part of the magnetic paint of the peripheral part of a magnetic disk. CONSTITUTION:When the magnetic paint is applied on the aluminum substrate 1 by a spin coating method, the phenomenon of the rise of the magnetic paint is generated in the peripheral part of the disk. When it is cured to have the magnetic disk, this part directly grows the rise part 6 to a magnetic layer to form an area incapable of being used in the peripheral part of the disk. In such a way, the bank part 8 of the magnetic paint is disposed on the peripheral part of the aluminum substrate so as to absorb the rise of the magnetic paint. Accordingly, the rise in the magnetic paint is absorbed to the bank part 8 of the aluminum substrate 1. Thereby, the protrusion part of the peripheral part of the disk is eliminated to enlarge the magnetic disk using area.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk, and more particularly to a coated magnetic disk manufactured by applying a magnetic paint to a substrate and curing it.

[Conventional technology]

The surface of the aluminum substrate used in conventional magnetic disks was processed to be flat, as described in "Precision Polishing Technology for Magnetic Disk Substrates" (Machinery and Tools, August 1984, p. 66). . Magnetic paint was spin-coated onto this aluminum substrate and cured to produce magnetic disks.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into consideration the possibility that a bulging portion of the magnetic layer is formed on the outer periphery of the magnetic disk, and there is a problem in that the area in which the magnetic disk can be used cannot be expanded.

An object of the present invention is to provide a magnetic disk whose usable area is expanded.

[Means for solving problems]

The above object is a magnetic disk having an aluminum substrate and a magnetic layer formed by coating and curing magnetic paint on the aluminum substrate, characterized in that a magnetic paint pooling portion is provided on the outer periphery of the aluminum substrate. This is accomplished by using magnetic disks.

[Effect]

When magnetic paint is applied to a conventionally shaped aluminum substrate by spin coating, a phenomenon occurs in which the magnetic paint bulges around the outer periphery of the disk. When this is hardened to form a magnetic disk, this portion directly becomes a raised portion (protrusion) of the magnetic layer, forming an unusable area on the outer periphery of the disk. Therefore, a pool of magnetic paint is provided on the outer periphery of the aluminum substrate so as to absorb this build-up of magnetic paint. Since the build-up of the magnetic paint is absorbed by the pooled portion of the aluminum substrate, no protrusions are formed on the outer periphery of the 5th disc, and the usable area of the outer periphery of the disc can be expanded.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a sectional view of a conventional magnetic disk, and FIG. 5 is a detailed sectional view of section A in FIG. A magnetic disk is manufactured by applying a magnetic paint to an aluminum substrate 1, curing it with heat, and applying a surface finish to form a magnetic layer 2. A detailed examination of the outer periphery of this magnetic disk reveals that there is a chamfered portion 5 on the outer periphery of the aluminum substrate 1, and a raised portion 6 of the magnetic layer near the intersection of this chamfered portion 5 and the flat portion 7 of the aluminum substrate. When trying to expand the usable area of the magnetic disk from position B to position C in FIG. The floating of head 3 becomes unstable,
This causes a flash accident between the magnetic disk and the magnetic head 3. Therefore, it is not possible to expand the usable area of the magnetic disk.

The present invention will be explained in detail using FIG. Aluminum substrate 1
A magnetic paint pooling portion 8 is provided at the intersection of the chamfered portion 5 and the flat portion 7 of the aluminum substrate. This absorbs the build-up of the magnetic paint and prevents it from forming a protrusion on the surface of the magnetic disk. Therefore, the surface of the magnetic disk becomes flat all the way to the outer periphery, and even if the magnetic head 3 is brought from position 1B to position IC, it will not come into contact with the magnetic disk. Therefore, it has become possible to expand the usable area of magnetic disks.

The shape of the magnetic paint accumulation portion 8 is such that the first stage chamfered portion is at an angle of approximately 15 to 60 degrees with respect to the flat portion 7 of the aluminum substrate.
Furthermore, from the intersection of the aluminum substrate flat part 7 and the chamfered part 5, 0.
Any shape may be used as long as the 5-50 μm portion is cut into an arc shape, a straight line shape, or the like. It is more preferable that the dimension H be 0.2-10-10-1 in the case of the circular arc shape shown in Fig. 1, and 54-50-11-10-1 in the case of the two-step chamfer shown in Fig.2. The same effect can be obtained even if the portion 8 has a stepped shape as shown in FIG. In this case H is 5IIIa ~ 50-
It is preferable that the incision inside 1 (in the direction of the center of the disk) is 2 to 3 mm. In addition, when the two-stage bevel shown in Fig. 2 is used.

It is clear that there may be three or more stages, and the stepped shape shown in FIG. 3 may be two or more stages, and the shape of a part of the two-stage chamfer may be combined with a circular arc shape. Although a small raised portion of the magnetic layer is shown in FIG. 3, it is clear that if the height is less than the flying height of the magnetic head, it will not come into contact with the magnetic head.

In the magnetic disk of the present invention, the magnetic layer is substantially flat up to the outer periphery, or the height of the raised portion is less than or equal to the flying height of the magnetic head. Therefore, the area in which magnetic disks can be used has been expanded. This is particularly effective for medium and small (5 inch, 3.5 inch, etc.) magnetic disks.

〔Effect of the invention〕

By providing a portion where magnetic paint accumulates on the outer periphery of the aluminum substrate according to the present invention, it is possible to eliminate protrusions caused by the accumulation of magnetic paint on the outer periphery of the magnetic disk, thereby expanding the area in which the magnetic disk can be used.

[Brief explanation of the drawing]

1, 2, and 3 are partial cross-sectional views of a magnetic disk according to an embodiment of the present invention, FIG. 4 is a cross-sectional view of a conventional magnetic disk, and FIG. 5 is a partial cross-sectional view of the magnetic disk of FIG. FIG. 1... Aluminum substrate 2... Magnetic layer 3... Magnetic head 4... Contact part 5... Chamfered part
6... Raised portion 7... Flat portion of aluminum substrate 8... Magnetic paint accumulation Patent attorney Junnosuke Nakamura Figure 1 Figure 4 Figure 5

Claims (1)

[Claims] 1. An aluminum substrate, and applying magnetic paint on the aluminum substrate.
1. A magnetic disk having a hardened magnetic layer, characterized in that a magnetic paint pool is provided on the outer periphery of the aluminum substrate.