JPH0280975A - Evaluation of magnetic disc medium - Google Patents

Abstract

PURPOSE:To evaluate the strength of a magnetic disk medium in an actual state within a short time by performing seek operation using a head disk assembly HDA and accelerating the contact state of the magnetic disk medium. CONSTITUTION:The HDA 4 of the evaluation device of a magnetic disk medium is arranged in a vacuum chamber 1 and, when this chamber is evacuated by a vacuum pump 3, the magnetic head 6 mounted on the actuator 8 of the HDA 4 under atmospheric pressure receives collaboration by the rotation of the magnetic disk medium 5 fixed to a spindle 7 to float above the medium 5. Further, the head 6 performs seek operation by the driving of the actuator 8 while holds a fine gap above the medium 5. A read error detector 11 detects the error of the signal read from the head 6 and accumulates the value thereof. Then, the seek operation of the head 6 is accelerated by the actuator 8 and the deterioration of the medium 5 is evaluated without performing long-time continuous operation.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for evaluating magnetic disk media, and is particularly applicable to KHL).
This is a magnetic disk medium evaluation method in which the contact between the magnetic head and the magnetic disk medium during a seek operation in an AC head disk assembly (AC head disk assembly) is increased by 71 G by disturbing only the flying of the magnetic head, and the strength of the magnetic disk medium is determined.

[Conventional technology]

The role of magnetic disk devices as external storage devices for computer systems has become increasingly important in recent years, and demands for higher distribution density and larger capacity are increasing. In order to meet all of these demands for higher recording density and larger capacity, it is inevitable that the flying height of the magnetic head relative to the magnetic disk medium be lowered, and currently the flying height is 0.2 nm to α5 μm. - As the flying height becomes lower, the possibility of information loss due to contact between the magnetic head and the magnetic disk medium, or so-called head crash, increases.

Head crash: There are two methods to avoid L1 and improve stability: reducing the vibration of the magnetic head and improving the strength of the magnetic disk, but from a fail-safe perspective, improving the strength of the magnetic disk tends to be prioritized. In order to improve the strength of the magnetic disk, it is necessary to improve the disk composition and lubricant2.
Although there are measures such as improving the disk surface shape, an evaluation method for comparing magnetic disk strengths is required to determine how much strength can be improved. As a conventional evaluation method, JP-A-60-
Collision test method described in No. 124073, JP-A-59-11
Single plate vacuum test method described in No. 578, JP-A-59-148
The vibration impact test method described in No. 117 is known.

[Problem that the invention seeks to solve]

As an evaluation method for magnetic disk media, it is desirable to perform evaluation using HDA, which is equivalent to the product, from the perspective of ensuring reliability.Also, in order to shorten the development period, it is possible to accelerate the actual operation state in HI)A. things are desirable. From this point of view, depending on the above-mentioned conventional technology, it is not possible to evaluate the HDA, or it is not possible to fully simulate the actual operating state in Ml)A. Furthermore, there is a problem that the actual operating state of Hl)A cannot be maintained at 710 speeds.

The object of the present invention is to provide a method for evaluating magnetic disk media that can be evaluated using an HDA equivalent to that of a product, and that can accelerate the actual operation of the HDK.

[Means for Solving the Problem J] The present invention provides a rotatably supported magnetic disk medium;
In order to record/reproduce information on a magnetic disk medium, there is a magnetic head that can float above the magnetic disk medium when the magnetic disk medium rotates, and a magnetic head that supports the magnetic head and moves it to any position on the magnetic disk medium. This can be accomplished by completely reducing the pressure inside the head disk assembly by including a fully movable positioning mechanism, disturbing the flying stability of the magnetic head, and bringing the magnetic head into contact with the magnetic disk medium. In other words, the head disk rises until the pressure reaches such a level that the magnetic head becomes unstable. By reducing the pressure inside J(Hl)A) and making the magnetic head float unstably, the magnetic head's imaging speed increases compared to the atmospheric pressure state where it floats stably, which increases the frequency of contact with the magnetic disk medium. , and in this unstable floating state, the magnetic head floating above the magnetic disk medium (i-movement (seek operation) accelerates the phenomenon that occurs due to long-time operation of HDA at atmospheric pressure, and reads This is accomplished by measuring the strength of the magnetic disk medium by measuring changes in the signal output.

[Function J] The HDA used in the evaluation is equivalent to that used in products, and the magnetic head stably floats above the rotating magnetic disk medium at atmospheric pressure. As the pressure inside HL)A is completely reduced, a region begins to appear in which the magnetic head flies unstable below a certain pressure P. Unstable levitation is a sudden change in the rigidity of the air film that makes the nod levitate magnetically.
Pitching of the magnetic head (rotational movement around the short axis of the head), rolling (rotational movement around the entire long axis of the head)
and up and down @ (parallel movement perpendicular to the magnetic disk medium)
It is said that the vibration of the metal increases rapidly. If the pressure is further reduced to below the pressure P, unstable levitation will occur in the entire area. Due to the unstable floating of the magnetic head, vibrations in the magnetic disk medium and the installation direction increase, and the frequency of contact between the magnetic head and the magnetic disk medium increases, causing the actual operating state of (L)A to change to D0 speed. It becomes ink.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained with reference to gold drawings.

Fig. 1 is a side view showing an evaluation device used in an embodiment of the present invention, and Fig. 3 is a functional conceptual diagram showing the flying state of the magnetic head due to pressure changes and frequency changes. In FIG. 1, an HDAd is installed, a magnetic disk medium 5 fixed to a spindle 7, a magnetic head 6 for recording and reproducing information on the disk medium 5, an actuator 8 for seeking the ffl head 6 onto the disk medium 5, and a breathing filter 9. , and a base 10t on which all these components are mounted. This HDA
4 is placed in the decompression chamber 1, and the vacuum pump 3 provides a decompression OT function. HL) The inside of A4 is at atmospheric pressure (to x
10''Pa), the magnetic head 6 attached to the actuator 8 receives lift from the rotation of the magnetic disk medium 5 fixed to the spindle 7.

It floats above this disk medium 5. The atmospheric pressure is sufficiently higher than the pressure P (approximately 4.5 x 10' P a ) at which the unstable flying region begins to appear as shown in Figure 3, and the magnetic head 6 flies stably. Further, driven by the actuator 8, the magnetic head 6 can move on the surface of the magnetic disk medium 5 while maintaining a minute gap (seek operation). The read error detection unit 11 detects a read error in the signal read by the magnetic head 6, and impulses the value.

Now, the pressure inside the decompression chamber 1 is reduced by the vacuum pump 3, and the pressure inside the chamber 1 is gradually reduced.

HD through the breathing filter 9 attached to HDA4
The inside of Aj is also reduced to the same atmospheric pressure as the inside of the decompression chamber 1.

Since the pressure inside the HDAJ is the same as that inside the decompression chamber 1 unless rapid pressure reduction is performed, the pressure can be measured by the pressure gauge 2 attached to the decompression chamber 1. When the pressure is reduced to below P (FIG. 3), an unstable floating region begins to appear in the magnetic head 6. Further reduce the pressure t,
Pressure P, (depends on circumferential speed. Approximately t7X at circumferential speed of 58 m/s
If the pressure is less than 10'Pa), the 1Mi air head 6 will fly unstable over the entire area.

Due to the appearance of an unstable floating region due to reduced pressure, the dynamic component of the magnetic head perpendicular to the magnetic disk medium 5 increases compared to when it is in a stable floating state, and the lower the pressure, the more the dynamic component increases.
L, the frequency of contact with the magnetic disk medium 5 increases. In this state, the actuator 8 is driven to move the magnetic head 6 over the entire surface of the magnetic disk medium 5 (seek operation). Deterioration of the magnetic disk medium 5 due to contact can be reproduced at an accelerated rate. More specifically, the pressure P in the head unstable flying region increases when the direct contact between the magnetic head 6 and the magnetic disk medium 5 increases.

During the HDA seek operation in the following cases and at atmospheric pressure, the normalized seek operation time T expressed in logarithm and the number of read errors Ng of the magnetic disk medium 5 caused by contact with the magnetic head 6 (according to the read error detection unit 11 When the detected value is measured, the relationship shown in FIG. 4 is obtained. The acceleration coefficient r of the deterioration of the magnetic disk medium 5 due to depressurization is the number of read errors at atmospheric pressure and during depressurization at one time t1.
, nl r-(m'/n+)lLCk is Nv,
-'r [tfl M A coefficient determined by K, and has pressure dependence. ), it can be predicted that the time t at which the magnetic disk medium 5 reaches the same deterioration level l1l (number of read errors) at atmospheric pressure as at reduced pressure is 4l-r-#. If we consider the usage limit of the magnetic disk medium 50, then t is the lifetime of the magnetic disk medium 5.

The strength life of the magnetic disk medium 5 can be predicted.

In addition, various magnetic disk media can be incorporated into the same HDA4,
- If the same evaluation as in the above is performed, the relationship shown in FIG. 5 will be obtained, making it possible to compare the strengths of magnetic disk media.

In this example, since disk B has fewer read errors than disk AJ in terms of seek operation time, disk B is relatively better. In this way, it is possible to evaluate a magnetic disk medium that satisfies the lifetime strength specifications.

FIG. 2 is a side view showing a configuration according to another embodiment. This example does not use vacuum chamber 1t- directly 1-IL)A
4f (it is designed to reduce the pressure, and this also allows for the same phenomenon as the configuration shown in FIG. 1 to occur.

〔Effect of the invention〕

According to the present invention, since it is possible to use HDA'i to perform seek operations and accelerate the contact state between the magnetic head and the magnetic disk medium, the strength of the magnetic disk medium can be evaluated in a relatively short time under actual machine conditions. It becomes possible to implement.

[Brief explanation of the drawing]

Fig. 1 is a side view of an evaluation device used in one embodiment of the present invention, Fig. Wc2 is a side view showing another embodiment, and Fig. 3 is an operational concept showing the floating state of the magnetic head due to pressure changes and frequency changes. Figure 4, Figure 4, and Figure 5 are diagrams showing the relationship between the normalized seek time and the number of read errors in the evaluation method according to this embodiment. 1... Decompression chamber, 2... Pressure gauge, 3... Vacuum pump. 4... HDA, 5... Magnetic disk medium, 6...
Magnetic head, 7... Spindle, 8... Actuator, 9... Breathing filter, 10... Base, 11
...Read error detection section. Collection No. f--5A Manmisenno 2-, Tamaga total 3--41 empty pumps--HDA 5--Manhiki, Te ≧ Zuku medium 6---To music score. ···········································Fig.

Claims (1)

[Claims] A rotatably supported magnetic disk medium, a magnetic head that can fly above the magnetic disk medium when the magnetic disk medium rotates in order to record/reproduce information on the magnetic disk medium, and In a head disk assembly that surrounds a positioning mechanism that can support and move the magnetic head to any position on the magnetic disk medium, the air pressure within the head disk assembly is reduced to stabilize the flying stability of the magnetic head. 1. A method for evaluating a magnetic disk medium, which comprises measuring the contact strength of a magnetic disk medium by disturbing the magnetic head and bringing a magnetic head into contact with the magnetic disk medium.