JPS62226423A - Magnetic disk - Google Patents

Abstract

PURPOSE:To obtain a desired lubricating effect for a long period of time by making the thickness of a lubricating film largest on the innermost periphery relative to the radial position of a magnetic disk and smaller toward the outer peripheral part. CONSTITUTION:Iron oxide (not shown) and epoxy resin (not shown) are coated on an Al substrate 1 having high purity and are thermally cured at a specified temp. to form a magnetic medium layer 2 thereon. The magnetic medium layer 2 contains fillers 3 consisting of alumina grains. The lubricating film 4 exists on the surface of the magnetic medium layer 2 to hold the disk surface. The thickness of the lubricating film 4 is made about 1/100 the thickness of the magnetic medium layer 2. The lubricating film 4 is so coated that the thickness thereof is largest on the inside peripheral part of the magnetic disk and is smaller toward the outside periphery. The desired lubricating effect is, therefore, obtd. for a long period of time even if the lubricating agent is migrated toward the outer peripheral region by centrifugal force.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk used in a magnetic disk device, and more particularly to a magnetic disk having a lubricating film attached thereto suitable for protecting the surface of the magnetic disk.

[Conventional technology]

In recent magnetic disk drives, a so-called contact start-stop system has become common, in which the magnetic disk slides against the head when starting and stopping the magnetic disk. For this reason, in order to reduce the frictional force during sliding and protect the surface of the magnetic disk, a fluorocarbon-based lubricating coating has come to be provided on the disk surface. In addition, to improve recording density,
The flying gap between an i-air head and a magnetic disk tends to become narrower year by year. As a result, contact between the head and the minute protrusions on the magnetic disk, or contact between the head and the disk due to the intrusion of dust, is likely to occur, and in order to reduce damage to the magnetic disk surface and head crashes, it is necessary to provide a The importance of lubricating films is increasing.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, simply increasing the thickness of the lubricating film,
If a large amount of it adheres to a magnetic disk, the head and disk may stick together while the magnetic disk is stopped, and the head and disk may be damaged when the disk is restarted. Therefore,
How to efficiently deposit a lubricating film is a necessary condition for improving the reliability of magnetic disk drives.

Conventionally, the thickness of the lubricating film was generally applied uniformly regardless of the radial position of the disk.
As stated in Publication No. 9-203241, the lubricating film gradually moves toward the outer circumference over a long period of time due to the centrifugal force caused by the rotation of the disk, and the film thickness on the inner circumference decreases to provide the desired lubrication. There was a disadvantage that no effect could be obtained. Therefore, maintaining the lubrication effect over the entire area of the magnetic disk for a long period of time is an important point in ensuring the reliability of the disk device.

An object of the present invention is to provide a magnetic disk that can maintain the effect of a lubricating film attached to the surface of a magnetic disk for a long period of time and prevent damage to the magnetic disk surface and head crash for a long period of time. be.

[Means for solving problems]

The magnetic disk of the present invention is characterized in that the thickness of the lubricating film is maximum at the innermost circumference of the magnetic disk and is deposited with a distribution that monotonically decreases as the disk radius increases.

[Effect]

According to the present invention, since a lubricant film is formed on the inner circumferential region of the disk that is easily moved toward the outer circumferential direction by the centrifugal force caused by rotation, even if the lubricant moves to the outer circumferential region due to the centrifugal force, the lubricant can remain in the desired state for a long period of time. A lubricating effect can be obtained.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to embodiments shown in the accompanying drawings.

Figure 1 shows a cross section of a magnetic disk.

Iron oxide (not shown) and epoxy resin (not shown) are coated on a high-purity AQ substrate 1 and thermally cured at a constant temperature to form a magnetic medium layer 2. This magnetic medium layer 2 contains filler (alumina particles) 3 as a reinforcing agent. The lubricating film 4 exists on the surface of the magnetic medium layer 2 and protects the disk surface. The actual thickness of the lubricant coating 4 is about 1/100 of the thickness of the magnetic medium layer 2, but the drawing is exaggerated.

FIG. 2 is a diagram showing an example of the relationship between the disk radius of a magnetic disk and the lubricant film thickness. As shown.

The coating is applied so that the film thickness is greatest at the inner circumference of the magnetic disk and decreases toward the outer circumference.

Lubricant lI! ! An effective method for forming i4 is to spray a lubricant solution onto the surface of the magnetic disk from a nozzle using a spray method, and control the film thickness by controlling the spray amount.

Next, a specific example will be given and explained. For a magnetic disk with an outer diameter of 14 inches and a magnetic disk with an outer diameter of 8 inches, the lubricant film thickness was set at 80°C and 6000 rpm for both the inner circumference>outer circumference and the conventional case where the thickness was uniform.
It was rotated for 3500 hours under the following conditions, and the film thickness before and after rotation was compared. The results are shown in Table 1.

Table 1 As is clear from Table 1, a 14-inch magnetic disk and an 8-inch magnetic disk
It can be seen that for both inch magnetic disks, if the initial thickness of the lubricant coating is expressed as inner circumference>outer circumference, a sufficiently thick lubricant coating remains in the inner circumference area even after 3,500 hours have elapsed.

Next, we conducted a contact start/stop test on the magnetic disks shown in Table 1 after 3,500 hours, and found that the conventional product, which had a lubricating film evenly applied in the radial direction of the magnetic disk, had a 14-inch magnetic field. 65 on disc
While scratches occurred on the 8-inch magnetic disk after 0 and 810 cycles, the five example products completed more than 1,000 cycles on both the 14-inch and 8-inch without any abnormalities.

As is clear from the above explanation, according to this embodiment, the thickness of the lubricant film in the inner circumferential area of the magnetic disk is the maximum, so even if the lubricant moves to the outer circumferential area due to centrifugal force, it will not work for a long time as desired. A lubricating effect can be obtained.

〔Effect of the invention〕

According to the present invention, the desired lubrication effect can be obtained for a long period of time, so damage to the surface of the magnetic disk and head crash can be prevented for a long period of time, which is effective in improving the reliability of the magnetic disk device. There is.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a magnetic disk, and FIG. 2 is a diagram showing an example of the relationship between the disk radius and the lubricant film thickness of the magnetic disk. DESCRIPTION OF SYMBOLS 1... AQ substrate, 2... Magnetic medium layer, 4... Lubricating film. Representative Patent Attorney Tadashi Akimoto Figure 1 Figure 2

Claims (1)

[Claims] 1. Having a magnetic medium layer for recording information on the substrate,
In a magnetic disk in which a lubricating film is applied to the surface of the magnetic medium layer, the thickness of the lubricating film is maximum at the innermost circumference and decreases toward the outer circumference with respect to the radial position of the magnetic disk. Features a magnetic disk.