JPH05151754A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent the deformation of a magnetic disk due to fastening the cap of a spindle motor for thinning the magnetic disk in accordance with the large capacity of a magnetic disk device. CONSTITUTION:This device is constituted so as to separate the cap 4 fixing the magnetic disk 1 to a spacer ring 3 and the thin cap and so as to use the spacer ring 3 whose both surfaces are wrapped. Thus, the deformation of the magnetic disk is suppressed and the magnetic characteristics of the magnetic disk 1 are nearly equal in both upper and lower surfaces and the radial value of an inner peripheral side is reduced, then, the large capacity as the magnetic disk device is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device, and more particularly to a hard disk device.

[0002]

2. Description of the Related Art Recently, there has been a remarkable demand for a large capacity of a magnetic disk device. In order to meet the demand as a magnetic disk device, 1. Increase the linear recording density (the number of bits per unit length). 2. Increase the track density (number of tracks per unit length). 3. Increase the number of magnetic disks. 4. Take a large recording area. And so on, and mainly by achieving 1 and 2, a large capacity has been achieved. Currently, even a 3.5-inch magnetic disk device has a linear recording density of 45 Kbpi and a track density of 2
It has been put to practical use at 500 TPI (track width of about 8 μm).

In order to further increase the capacity of the magnetic disk device, the number of magnetic disks is increased, or a recording radius value of 23.5 to 24. It is possible to make 0mm smaller.

However, the magnetic disk device has a limitation that it is generally used for the entire height, and it is 41 mm for a half height and 25.4 mm for an inch height. Therefore, in order to increase the number of magnetic disks, the distance between the magnetic disks is narrowed or the thickness of the magnetic disks themselves is reduced.

A conventional magnetic disk device will be described with reference to the sectional view of FIG. FIG. 3 shows a 3.5-inch magnetic disk device having a half-height specification. 1A, 1B, 1C
... is a magnetic disk, and its thickness is about 0.8 mm. The number and thickness of magnetic disks are not limited to the six shown. A spindle motor 2 is fixed to the base 9. 3 is a spacer ring and 4 is a cap.
Reference numeral 5 is a magnetic head, 6 is a flexure that supports the magnetic head, and 7 is an arm that holds the flexure and is movable substantially parallel to the magnetic disk. Reference numeral 8 is a carriage for moving the arm. Further, as shown in FIG. 2, the magnetic disk 1 is fixed to the spindle motor 2 by fixing the cap 4 with six screws.

[0006]

However, when the thickness of the magnetic disk becomes thin, the cap of the spindle motor is tightened as shown in FIG. When the magnetic disk itself is warped, the magnetic film deposited is also warped. The magnetic film itself has magnetostriction, and its magnetic characteristics change depending on the force received. In this case, since the upper surface and the lower surface of the magnetic disk receive the opposite force of the compressive force and the tensile force, the magnetic characteristics of the upper surface and the lower surface of the magnetic disk change in opposite directions as shown in FIG. .. The direction of change depends on whether the magnetostriction is positive or negative. For this reason, there is a problem in that there is a difference in the electromagnetic conversion characteristics between the upper surface and the lower surface of the magnetic disk, and the output and resolution deteriorate on the surface having poor magnetic characteristics, and the reliability of data decreases.
In addition, there is a problem that the portion where the screw is tightened is particularly deformed, and the radius value of the inner circumference cannot be reduced from the viewpoint of fluctuation of the flying height and reliability. This is caused by the deformation of the cap that fixes the magnetic disk, and is due to the distribution of the tightening force in the circumferential direction and the radial direction.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a magnetic disk device in which a magnetic disk is not deformed into a concave surface or a convex surface, and a screw portion is not deformed.

[0008]

In order to achieve the above object, the present invention provides a magnetic disk, a spindle motor for holding the magnetic disk, an arm that moves substantially parallel to the magnetic disk, and the arm. In a magnetic disk device including a flexure attached to the flexure and a floating magnetic head attached to the flexure, when fixing the magnetic disk, the magnetic disk is further provided on the uppermost magnetic disk via a spacer ring. The disk is fixed from above with a cap. Further, the spacer ring used is processed by double-sided lapping.

[0009]

According to the present invention having the above-mentioned structure, the magnetic disk can be prevented from being deformed even if the cap is closed when the magnetic disk is fixed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention is shown in FIGS. Figure 1
Is a sectional view and FIG. 2 is a perspective view. Reference numeral 10 is a spacer ring newly provided in the present invention, and the other portions are the same as those of the conventional one described in FIG. 3, and therefore detailed description thereof will be omitted.

In the first embodiment, the uppermost spacer ring 10 which is double-sided is further provided between the spacer ring 3 and the cap 4, and in the second embodiment, the spacer ring 3 is used. The structure is such that an elastic spacer ring is interposed between the uppermost spacer ring 10 and the cap 4 by using a material processed by ordinary grinding or lathe.

As a comparative example, a comparison of characteristics with the conventional magnetic disk drive shown in FIG. 3 is shown in Table 1.

[0013]

[Table 1]

The thickness of all magnetic disks was 0.8 mm as in the examples. The conventional disk fixing cap has a structure in which the cap and the uppermost spacer ring in the embodiment are combined. First, the output at the inner circumference of 24.0 mm was measured for Examples and Comparative Examples. The measurement frequency is an output f = 4 MHz, and the magnetic disks are A, B, C, D, E and F from the bottom of the spindle motor as shown in FIGS. 1 and 3, and the surfaces are a, b and c from the bottom of the spindle motor. ，
… K and l. As shown in (Table 1), in the first embodiment, there is almost no difference between the upper surface and the lower surface of the magnetic disk, and substantially constant characteristics are obtained. The characteristics have deteriorated, and the reliability of the data on the magnetic disk has deteriorated. This is caused by the surface deformation of the magnetic disk surface into concave or convex as shown in FIG. This surface deformation means that the tightening force from the cap does not work perpendicularly to the surface of the magnetic disk, and the spacer
Caused by non-parallelism on both sides of the ring.

Next, as shown in FIG. 4, the deformation of the magnetic disk surface was measured using an optical displacement gauge while the cap was closed. The measurement was performed at a radius of 25 mm, 22.5 mm and 20 mm. Results are shown in FIG. In the first embodiment, the surface of the magnetic disk has a substantially flat surface, whereas in the comparative example, the smaller the radius is, the larger the deformation is, and the six irregularities corresponding to the screws are formed. It occurs on the surface. When the inner radius value is reduced, the reproduction signal is deteriorated due to the flying height variation, and the reliability problem during CSS occurs. However, with the structure of this embodiment, the inner radius value can be reduced. (CSS is an abbreviation for contact start stop, which is a method of starting and stopping the magnetic disk).

In the case of the second embodiment, instability remains with respect to surface deformation, but the amount of deformation can be relaxed. Further, when the magnetic disk becomes thinner, the above problem can be suppressed by interposing a ring made of an elastic material between the cap and the uppermost spacer ring.

[0017]

As is apparent from the description of the above embodiment, the present invention attaches to a magnetic disk, a spindle motor for holding the magnetic disk, an arm that moves substantially parallel to the magnetic disk, and an arm. And a floating magnetic head attached to the flexure, wherein a cap for fixing the disk is separated into a spacer ring and a thin cap when fixing the magnetic disk. By using a spacer ring having both sides lapped, the magnetic disk can be prevented from being deformed even when the cap is tightened, so that the magnetic characteristics can be made substantially constant on the upper surface and the lower surface of the magnetic disk, The reliability of data can be improved and the inner radius value can be reduced. , It is possible to achieve a large capacity as a magnetic disk device.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetic disk device according to an embodiment of the present invention.

FIG. 2 is a perspective view of the same.

FIG. 3 is a sectional view of a conventional magnetic disk device.

FIG. 4 is a perspective view of measuring a deformation amount of a magnetic disk.

FIG. 5 is a characteristic diagram showing a displacement amount of a magnetic disk.

FIG. 6 is a cross-sectional view illustrating a warp of a magnetic disk of a conventional magnetic disk device.

FIG. 7 is a characteristic diagram showing changes in magnetic characteristics due to warpage.

[Explanation of symbols]

 1 magnetic disk 2 spindle motor 3 spacer ring 4 cap 5 magnetic head 6 flexure 7 arm 10 uppermost spacer ring

Claims (3)

[Claims] 1. A magnetic disk, a spindle motor that holds the magnetic disk, an arm that moves substantially parallel to the magnetic disk, a flexure attached to the arm, and a floating magnetic element attached to the flexure. A magnetic disk device comprising a head, wherein the magnetic disk is fixed via an uppermost spacer ring between the magnetic disk and a cap. 2. The magnetic disk drive according to claim 1, wherein a spacer ring made of an elastic material is arranged between the uppermost spacer ring and the cap. 3. The magnetic disk drive according to claim 1, wherein the spacer ring is lapped on both sides.