JP2885178B2 - Magnetic disk drive reliability evaluation method and magnetic disk drive using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for evaluating the reliability of a magnetic disk device used as an external storage device of a computer system and a magnetic disk device using the same.

[0002]

2. Description of the Related Art Conventionally, as a method for detecting contact between a magnetic head slider and a magnetic disk in a magnetic disk drive, a method using an AE (Acoustic Emission) sensor as disclosed in Japanese Patent Application Laid-Open No. 61-32278 has been proposed. well known.

The main purpose of using the AE sensor is to detect contact to prevent the magnetic slider from dropping and damaging the magnetic disk surface due to the presence of magnetic powder and the like.

In a recent magnetic disk drive, a magnetic head slider floats on a magnetic disk rotating at a high speed by the dynamic pressure of air, and the magnetic head slider used in this magnetic disk drive has a large capacity. In order to increase the recording density, the distance between the magnetic disk and the magnetic head slider is becoming narrower.

[0005] However, when trying to realize a small interval, the probability of the magnetic head slider contacting or colliding with the magnetic disk is increased, and a head crash or other trouble tends to occur.

The surface of the magnetic disk is a CSS (Contac
When it is combined with a magnetic head slider of the (t Start Stop) type, wear occurs due to contact sliding with the magnetic head slider. For this reason, improvement in the wear resistance of the magnetic disk is required, and a test method and apparatus capable of effectively evaluating the wear resistance, ie, the durability, of the magnetic disk are required.

[0007]

The above-mentioned conventional device has the following problems.

(1) In a recent magnetic disk drive, the reliability has been improved. Therefore, the life of the magnetic disk drive is not limited to the time when intermittent contact occurs between the magnetic head slider and the magnetic disk. It should be considered that the protection film on the magnetic film starts to be exposed when the lubricating oil is depleted.

However, in the above-described conventional apparatus, only the presence or absence of contact between the magnetic head slider and the magnetic disk is detected.

(2) When the contact between the magnetic head slider and the magnetic disk is detected, the protection function of the magnetic disk device works when the contact is detected, so that the capacity and density of the magnetic head slider can be increased. In the case where there is no space between the magnetic head slider and the magnetic disk, the protection function works meaninglessly.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has been developed in consideration of the reliability evaluation at the time when the lubricating oil is depleted and the protective film on the magnetic film starts to be exposed. It is an object of the present invention to provide a method for evaluating the reliability of a magnetic disk device capable of performing the above-mentioned, and a magnetic disk device using the same.

[0012]

In order to achieve the above object, the present invention provides a magnetic film on which information is recorded, a protective film applied on the magnetic film, and a lubricating material applied on the protective film. A magnetic head slider provided on a magnetic disk including oil, for writing information on the magnetic disk and reading information recorded on the magnetic disk; and detecting a contact state between the magnetic head slider and the magnetic disk. A method for evaluating the reliability of a magnetic disk drive having a contact sensor, the method comprising: determining whether an output value from the contact sensor is equal to or higher than a predetermined first determination level; When it is determined that the value is equal to or higher than the predetermined first determination level, the subsequent output value from the contact sensor is lower than the first determination level. And evaluating the reliability by determining whether a second judgment level below a predetermined order.

Further, the second determination level is a level at which it is possible to determine a state in which the lubricating oil is partially depleted and the protective film is partially exposed.

In a magnetic disk drive utilizing the above-described method for evaluating the reliability of a magnetic disk drive, it is determined whether an output value from the contact sensor is equal to or higher than the first determination level. A comparison circuit that determines whether an output value from the contact sensor is equal to or less than the second determination level, and an output value from the contact sensor is equal to or less than the second determination level in the comparison circuit. And an actuator control circuit for outputting a signal for moving the magnetic head slider to the landing zone when it is determined that

A motor control circuit for outputting a signal for stopping the motor rotating the magnetic disk when the comparison circuit determines that the output value from the contact sensor is equal to or lower than the second determination level; It is characterized by having.

Further, the contact sensor may be an Acoustic Emi
It is a ssion sensor.

(Operation) In the present invention constructed as described above, the reliability of the magnetic disk drive is evaluated based on the contact state between the magnetic head slider and the magnetic disk detected by the contact sensor. The evaluation is based on whether the output value from the contact sensor has fallen below the level at which the lubricating oil applied to the magnetic disk can be partially depleted and the protective film can be partially exposed. Will be

When the output value from the contact sensor falls below a level at which it can be determined that the state of the protection film partially exposed due to the partial depletion of the lubricating oil applied to the magnetic disk. Outputs a signal for stopping the drive of the magnetic disk drive.

As described above, the reliability of the magnetic disk drive is evaluated when the lubricating oil applied on the magnetic disk is depleted and the protective film on the magnetic film starts to be exposed.

[0020]

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

FIG. 1 is a diagram for explaining an embodiment of a reliability evaluation method for a magnetic disk drive according to the present invention.
(A) is a figure which shows the normal levitation state, (b) is a figure which shows the output of the contact sensor in the state shown to (a).

In this embodiment, as shown in FIG. 1, a magnetic disk 2 on which information is recorded, and a magnetic disk 2 provided on the magnetic disk 2,
Magnetic head slider 1 for writing information on magnetic disk 2 and reading information recorded on magnetic disk 2
An arm suspension 3 supporting the magnetic head slider 1, a holder arm 4 supporting the arm suspension 3, and an AE (Acoustic Emission) for detecting a contact state between the magnetic head slider 1 and the magnetic disk 2.
The magnetic disk 2 includes a substrate 10 and a magnetic film 8 on which information is recorded.
And protective films 7, 9 applied on the magnetic film 8 to protect the magnetic film 8, and a fluorine-based material applied on the protective film 7 to smooth the contact between the magnetic disk 2 and the magnetic head slider 1. And a lubricating oil 6 such as a liquid lubricant.
The magnetic disk 2 is driven to rotate by a spindle motor (not shown) provided outside.

When the magnetic head slider 1 as shown in FIG. 1 (a) flies and is completely separated from the magnetic disk 2, the amplitude of the voltage output from the contact sensor 5 is as shown in FIG. 1 (b). As shown, small, only noise level.

FIGS. 2A and 2B are diagrams showing a state in which the magnetic head slider 1 and the magnetic disk 2 are in contact with each other in the reliability evaluation method of the magnetic disk device shown in FIG. 1, wherein FIG. FIG. 4 is a diagram showing an output of the contact sensor in the state shown in FIG.

When the magnetic head slider 1 is in contact with the magnetic disk 2 as shown in FIG. 2A, the amplitude value of the voltage output from the contact sensor 5 is as shown in FIG. 2B. growing.

FIG. 3 is a view showing a state in which the lubricating oil 6 is depleted and the protective film 7 is exposed on the surface of the magnetic disk 2 in the reliability evaluation method of the magnetic disk device shown in FIG.
(A) is an external view, (b) is a figure which shows the output of the contact sensor in the state shown to (a).

As shown in FIG. 3A, when the contact sliding proceeds, the lubricating oil 6 is depleted, and the protective film 7 is exposed on the surface of the magnetic disk 2. Then, the amplitude value of the voltage output from the contact sensor 5 decreases as shown in FIG.

FIG. 4 is a view showing a state where the protective film 7 is worn out and the magnetic film 8 is exposed on the surface of the magnetic disk 2 in the reliability evaluation method of the magnetic disk device shown in FIG.
(A) is an external view, (b) is a figure which shows the output of the contact sensor in the state shown to (a).

As shown in FIG. 4A, when the contact sliding further proceeds, the protective film 7 is worn, and the magnetic film 8 is exposed on the surface of the magnetic disk 2. Then, the amplitude value of the voltage output from the contact sensor 5 increases as shown in FIG. Here, the amplitude value of the voltage shown in FIG. 4B is large in the portion where the magnetic film 8 is exposed.

FIG. 5 is a graph showing the amplitude value of the voltage output from the contact sensor 5 in each state shown in FIGS.

The graph shown in FIG. 5 shows the results of two experiments, and it can be seen that the graph has good reproducibility.

Since the amplitude value of the voltage output from the contact sensor greatly changes when the lubricating oil 6 applied on the magnetic disk 2 is depleted, it is possible to separate the time point. When the lubricating oil 6 is depleted and the protective film 7 is worn, a head crash occurs.
Considering that the presence / absence of the lubricating oil does not affect the recording / reproducing signal, it is considered that the point at which the lubricating oil 6 is depleted is the limit for ensuring reliability.

FIG. 6 is a diagram showing a configuration example of a magnetic disk drive to which the reliability evaluation method of the magnetic disk drive shown in FIGS. 1 to 4 is applied.

The magnetic disk drive according to the present embodiment includes an averaging circuit 11 for averaging the output value from the contact sensor 5 and an amplitude width of the voltage averaged in the averaging circuit 11 to a predetermined constant value. A comparison circuit 12 for comparison; a latch circuit 13 for temporarily holding a comparison result in the comparison circuit 12; an actuator control circuit 14 for moving the magnetic head slider 1 based on an output value from the latch circuit 13; A spindle motor control circuit 15 for stopping a motor rotating the magnetic disk 2 based on the output value.

Hereinafter, the operation of the magnetic disk drive configured as described above will be described.

FIGS. 7A and 7B are diagrams for explaining the operation of the magnetic disk drive shown in FIG. 6, wherein FIG. 7A shows the output value of the averaging circuit 11, and FIG. It is a figure showing a value.

FIG. 8 is a flowchart showing the operation of the magnetic disk drive shown in FIG.

Here, as shown in FIG. 7 (a), the noise level of the contact sensor 5 is L1, the maximum average output when the lubricating oil is worn is L2, and when the lubricating oil is completely depleted and the protective film is exposed. Is L3, and the first output is between L2 and L3.
The second judgment level V2 is provided between V1 and V1 and L3. In addition,
At V2, the level is set so that it can be determined that the lubricating oil is partially depleted and the protective film is partially exposed.

First, the contact sensor 5 detects a contact state between the magnetic head slider 1 and the magnetic disk 2 (step S101).

Next, in the averaging circuit 11,
The detection results of the contact sensor 5 are averaged (Step S102).

Next, in the comparison circuit 12, the output value from the averaging circuit 11 is compared with V1 (step S103). If the output value from the averaging circuit 11 is less than V1, the lubricating oil is effectively used. It is determined that a contribution has been made (step S104), and the averaging circuit 11
If the output value from is more than V1, it is determined that the lubricating oil is partially worn (step S105).

When it is determined that the lubricating oil is partially worn, the latch circuit 13 holds and outputs V1 (step S106).

Next, the comparison circuit 12 compares the output value from the averaging circuit 11 with V2 (step S107). If the output value from the averaging circuit 11 exceeds V2, the lubricating oil is removed. It is determined that the protective film has been worn but is covered (step S108), and if the output value from the averaging circuit 11 is equal to or less than V2, the lubricating oil is partially depleted and the protective film is partially removed. It is determined that it is exposed (step S109).

When it is determined that the protection film is partially exposed, V2 is held and output in the latch circuit 13 (step S110).

When V2 is output from the latch circuit 13,
The magnetic head slider 1 moves to the landing zone under the control of the actuator control circuit 14, and the motor rotating the magnetic disk stops under the control of the spindle motor control circuit 15 (step S11).
1).

By the above-described series of operations, the drive of the magnetic disk drive can be stopped when the lubricating oil is exhausted.

Here, when the lubricating oil is exhausted, since the protective film is still present, it is possible to take a countermeasure such as a backup, and no data is damaged.

In this embodiment, V1 = 0.2
V, V2 = 0.1V, L1 = 0.02V, L2 = 0.3
V, L3 = 0.065V.

[0049]

Since the present invention is configured as described above, it has the following effects.

(1) A state in which the lubricating oil applied to the magnetic disk is partially depleted and the protective film is partially exposed based on the state of contact between the magnetic head slider and the magnetic disk detected by the contact sensor. It is determined whether the level is below the level at which it can be determined that the magnetic flux is below the threshold, and the reliability is evaluated based on the determination result. Can be evaluated for reliability.

(2) Since the reliability is evaluated when the lubricant is depleted and the protective film on the magnetic film starts to be exposed, even in a magnetic disk device having no space between the magnetic disk and the magnetic head slider. A reliability evaluation can be performed.

(3) When the output value from the contact sensor falls below a level at which it can be determined that the lubricant applied to the magnetic disk is partially depleted and the protective film is partially exposed. In addition, since a signal for stopping the drive of the magnetic disk drive is output, data is not damaged.

As is apparent from the above effects, according to the magnetic disk drive reliability evaluation method of the present invention and the magnetic disk drive using the same, the contact sensor for detecting the contact between the magnetic head slider and the magnetic disk surface is provided. At
By adopting a configuration in which a sign of head crash is detected at the time of lubricating oil depletion, it is possible to perform reliability evaluation excellent in reproducibility and sensitivity. In addition, since the magnetic head slider does not slide at high speed for a long time on the magnetic disk on which the protective film is exposed due to the depletion of the lubricating oil, the magnetic disk has high reliability without causing data destruction due to scratches on the magnetic disk. A magnetic disk drive can be provided.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams for explaining an embodiment of a method for evaluating the reliability of a magnetic disk drive according to the present invention, wherein FIG. 1A shows a normal flying state, and FIG. It is a figure showing an output of a contact sensor in a state.

2A and 2B are diagrams showing a state in which a magnetic head slider and a magnetic disk are in contact with each other in the reliability evaluation method of the magnetic disk device shown in FIG. 1, wherein FIG. 2A is an external view and FIG. It is a figure showing an output of a contact sensor in the state shown.

3A and 3B are diagrams showing a state in which lubricating oil is depleted and a protective film is exposed on the surface of the magnetic disk in the reliability evaluation method of the magnetic disk device shown in FIG. 1, wherein FIG.
(B) is a figure which shows the output of the contact sensor in the state shown to (a).

4A and 4B are diagrams showing a state in which a protective film is worn and a magnetic film is exposed on the surface of a magnetic disk in the reliability evaluation method of the magnetic disk device shown in FIG. 1, wherein FIG.
(B) is a figure which shows the output of the contact sensor in the state shown to (a).

FIG. 5 is a graph showing the amplitude value of the voltage output from the contact sensor in each of the states shown in FIGS.

FIG. 6 is a diagram showing a configuration example of a magnetic disk device to which the reliability evaluation method of the magnetic disk device shown in FIGS. 1 to 4 is applied;

7A and 7B are diagrams for explaining the operation of the magnetic disk device shown in FIG. 6, wherein FIG. 7A is a diagram showing an output value of an averaging circuit, and FIG. 7B is a diagram showing an output value of a comparison circuit; is there.

8 is a flowchart showing the operation of the magnetic disk device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic head slider 2 Magnetic disk 3 Arm suspension 4 Holder arm 5 Contact sensor 6 Lubricant 7, 9 Protective film 8 Magnetic film 10 Substrate 11 Averaging circuit 12 Comparison circuit 13 Latch circuit 14 Actuator control circuit 15 Spindle motor control circuit

Claims (5)

(57) [Claims] 1. A magnetic disk provided on a magnetic disk comprising a magnetic film on which information is recorded, a protective film applied on the magnetic film, and a lubricating oil applied on the protective film. Evaluation of the reliability of a magnetic disk drive comprising: a magnetic head slider for writing information to the magnetic disk and reading information recorded on the magnetic disk; and a contact sensor for detecting a contact state between the magnetic head slider and the magnetic disk. In the method, it is determined whether an output value from the contact sensor is equal to or higher than a predetermined first determination level, and if the output value from the contact sensor is equal to or higher than the predetermined first determination level. If determined, whether the subsequent output value from the contact sensor is equal to or less than a predetermined second determination level lower than the first determination level A reliability evaluation method for a magnetic disk drive, characterized in that reliability is evaluated by judging the reliability. 2. The reliability evaluation method for a magnetic disk drive according to claim 1, wherein the second determination level is a state in which the lubricant is partially depleted and the protective film is partially exposed. A method for evaluating the reliability of a magnetic disk drive, which is at a level at which it can be determined. 3. A magnetic disk drive using the magnetic disk drive reliability evaluation method according to claim 1 or 2, wherein an output value from said contact sensor is equal to or higher than said first determination level. A comparison circuit that determines whether or not the output value from the contact sensor is equal to or less than the second determination level. In the comparison circuit, the output value from the contact sensor is An actuator control circuit for outputting a signal for moving the magnetic head slider to a landing zone when it is determined that the magnetic head slider is below the second determination level. 4. The magnetic disk drive according to claim 3, wherein the magnetic disk is rotated when the comparison circuit determines that the output value from the contact sensor is equal to or less than the second determination level. A magnetic disk drive comprising a motor control circuit for outputting a signal for stopping a motor. 5. The magnetic disk drive according to claim 3, wherein the contact sensor is an acoustic emission sensor.