JP2001118349A - Disk device and information storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the head switching time from surpassing a desired time by stopping the increase of an inter-head offtrack while a magnetic disk device operates due to dimple slip of a head support mechanism. SOLUTION: This device carries out a CSC or an unload operation when the head switching time becomes long.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk device used for an external storage device of a computer and an information storage device using the disk device.

[0002]

2. Description of the Related Art In a disk apparatus, when recording / reproducing information over a plurality of tracks, a track for recording / reproduction is changed by switching a head within a predetermined time (skew time). In a normal disk (recording medium), when the head is switched from a certain track n to the next track n + 1, the track n + 1 is shifted from the last data of the track n by a distance corresponding to the rotation of the disk of the recording medium during the skew time. The first data is formatted so that recording / reproduction of information can be started immediately after head switching (immediately after the skew time elapses).

The time for switching the head from track n to the next track n + 1 is called a head switching time. The time set as the skew time is a time obtained by giving a margin to the time required for the normal head switching time.

A head slider of a disk drive is
Until an evacuation command or an unload command to the CSS zone is issued by a stop command or the like, it is floating on the disk for a long time.

[0005]

However, if the head switching time is increased for some reason and becomes longer than the skew time, the head position immediately after the switching is past the start position (first data position) of the track. After the disk rotates once, the recording / reproduction of information on the next track is started. Therefore, extra time is required for recording / reproducing information, and the processing time of the magnetic disk device is increased.

One of the main reasons why the head switching time is increased is that the head support mechanism is dimple-slid. When the dimple of the head support mechanism slides, the head element shifts with respect to the actuator that drives the head. This is called dimple slip, and the deviation from the position (reference position) where the head element should originally be located at that time is the amount of deviation due to dimple slip.

The direction (inner side / outer side of the disk) differs for each head depending on the amount and mode of the shift, so the amount of shift between head elements of each head, that is, the amount of off-track between heads increases. When the off-track amount between heads increases, the moving distance at the time of head switching increases, and as a result, the head switching time increases.

[0008] This dimple slip occurs at the time of a seek error or the like, and causes CSS (contact start / stop).
In the case of the system, it also occurs at the time of CSS, at the time of releasing adhesion, and the like.

If the slider continuously floats on the disk for a long time, dust adheres to the flying surface of the slider, the flying height increases, the recording / reproducing characteristics are deteriorated, and the recording / reproducing command is not performed. Is re-recorded / re-produced, and the number of inputs / outputs per unit time is reduced. Furthermore, repeated re-recording /
Replaying is performed, the input / output characteristics of the disk device are reduced,
The input / output characteristics of the storage device using the disk device are degraded.

[0010]

When dimple slippage occurs and the head switching time increases, the head slider and the disk are rubbed at a certain yaw angle. The yaw angle is the angle formed by the disk circumferential tangent to the head slider, and has the opposite sign to the angle formed by the slider to the disk circumferential tangent called the skew angle. When the head slider and the disk are rubbed at a certain yaw angle, all the heads in the magnetic disk drive are pulled in a certain direction (for example, on the inner peripheral side) by the frictional force between the disk and the head slider. The positional deviation of the actuator caused by slipping of the dimple is fixed in a certain direction (for example, the inner circumferential direction) from the initial position.
Can be aligned.

The positional deviation of the head element caused by the dimple slip is not fixed in a fixed direction such as the inner circumferential direction or the outer circumferential direction of the disk. The amount of truck can be halved. As a result, the once increased head-to-head off-track amount becomes smaller again, and the head switching time falls within the skew time.

Similarly, instead of rubbing the head slider and the disk, the actuator is caused to collide with either the inner circumference or the outer circumference, and an operation of gradually reducing the collision force is performed, thereby temporarily increasing the magnitude. The off-track amount between heads becomes smaller again, and the head switching time falls within the skew time.

As another method, unloading the head slider is effective in correcting dimple slip. This is because a phenomenon occurs in which the dimple and the gimbal tongue are separated during the unloading operation, and the frictional force acting at the moment when the dimple and the gimbal tongue are separated becomes zero. At this time, the gimbal tongue is pulled back to almost the neutral point by the reaction force acting on the gimbal arm, so that the dimple slip is corrected.

The problem is that the slider flies above the disk for a long time, dust or the like adheres to the slider's flying surface, and the flying height increases, resulting in deterioration of recording / reproducing characteristics and deterioration of input / output characteristics of the disk device. Regarding the point, when the number of times of input / output per unit time of the disk device is equal to or less than a predetermined number of times, or when input errors / output errors occur continuously and exceed the predetermined number of times, The problem can be solved by causing the head slider and the disk to rub when the operating time of the head becomes longer than a predetermined time.

[0015]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart of an operation showing an embodiment of the present invention, and FIG. 2 is a perspective view of a magnetic disk drive for implementing the flowchart of FIG. If the head switching time repeatedly exceeds a predetermined time (skew time), a contact start / stop (CSS) is performed. This magnetic disk device is a recording medium (a magnetic disk in this embodiment)
Has a CSS zone 2 on the inner peripheral side of the disc 1
At this time, the head slider (the magnetic head slider in this embodiment) 3 is located in the CSS zone 2. In the CSS zone 2, the head slider 3 has an angle with respect to the circumferential direction of the disk 1. When the head slider 3 comes into contact with the disk 1, the circumferential direction of the disk 1, It is pulled to the outer peripheral side 5 with respect to the longitudinal direction.

FIG. 3 is an enlarged view of the head support mechanism 4. The head slider 3 is fixed to a gimbal tongue 6 of a head support mechanism 4. The gimbal tongue 6 is integral with the gimbal arm 7 and is supported in contact with the dimple 9 of the load beam 8 of the head support mechanism 4. The root of the load beam 8 of the head support mechanism 4 is fixed via a carriage 11 to a motor 10 for positioning and driving the head support mechanism 4. The head support mechanism 4, the carriage 11, and the motor 10 are collectively called an actuator 12.

The position of the head slider 3 with respect to the actuator 12 includes the spring force of the gimbal arm 7 (hereinafter, spring force), the frictional force between the dimple 9 and the gimbal tongue 6 (hereinafter, frictional force), the head slider It is determined by the balance with the external force applied to 3 (hereinafter, external force).

When frictional force ≧ spring force + external force, the position of the head slider 3 with respect to the head support mechanism 4 is constant.

When frictional force <spring force + external force, relative movement (dimple slip) occurs between the dimple 9 and the gimbal tongue 6, and the head support mechanism of the head slider 3 is located at a position where frictional force = spring force + external force. 4 is determined.

Among the three factors that determine the position of the head slider 3 with respect to the load beam 8, the frictional force and the spring force vary depending on the individual head support mechanisms 4. Therefore, even if an external force of the same magnitude is applied to all the head sliders 3 by the head positioning operation, the head slider 3 is moved to the outer peripheral side 5 with respect to the longitudinal direction of the head support mechanism 4 with respect to the neutral point where the spring force becomes zero. The head sliders 3 are offset relative to each other, causing a relative positional shift between head sliders 3 (off-track between heads). After information is recorded / reproduced by one head slider 3, information of another head slider 3 is recorded. When reproducing / reproducing (when switching the head), the actuator 12 needs to be operated. The time required for the operation of the actuator 12 is called a head switching time.

The head switching time is determined by the off-track amount between heads. If the amount of information to be recorded / reproduced does not fit on one track, recording / reproduction is performed while switching the head. At this time, in order to perform recording / reproduction in a short time, the head of a continuous track is set at a position where the disk is rotated for a predetermined head switching time. Therefore, if the actual head switching time exceeds the predetermined head switching time, an operation (rotation wait) of making one revolution and waiting for the next head of the track occurs (write or reproduction time becomes extremely long). Occurs.

One major cause of the rotation waiting is an increase in off-track between heads caused by the dimple slip in the above-mentioned direction. According to the present embodiment,
By performing the CSS, the head displacement due to the dimple slip can be aligned in one direction, so that the increased off-track between heads can be reduced, and the problem due to the off-track between heads can be solved.

For example, a skew time is defined as 1 ms in a magnetic disk drive equipped with an actuator 12 that can move a distance of 5 μm in 1 ms. In this case, if the off-track amount between heads is 5 μm or less, head switching can be performed within 1 ms, so that head switching is in time for the skew time. However, when the off-track amount between heads becomes 5 μm or more due to dimple slip, the head switching time takes 1 ms or more. Therefore, when the head is switched, the desired position has passed, and the user has to wait one rotation to access the data.

Therefore, if this rotation wait occurs several times in succession (for example, three times), the head slider 3 and the disk 1
To rub at a constant yaw angle (8-10 °)
Perform S.

In this magnetic disk drive, the angle of the head slider 3 in the CSS zone with respect to the circumferential direction of the disk 1 is 10 °, and the force with which the head slider 3 is pulled in the circumferential direction of the disk 1 by the CSS. In the case of 20 mN,
The head slider 3 is 3.5 mN on the outer peripheral side 5 by CSS.
(= 20 mN × sin 10 °).

When the pressing load of the dimple 9 is 10 mN and the static friction coefficient is 0.33, the dimple slip is 3.
It occurs at 3 mN (= pressing load x static friction coefficient) or more. Since the pulling force (external force) is 3.5 mN as described above, dimple slip occurs in this case.

As a result, the positional deviation of all the head sliders 3 with respect to the actuator 12 can be made uniform to the outer peripheral side 5 from the initial position by the CSS. Although the positional deviation of the head element caused by the dimple slip is not fixed in a fixed direction such as the inner circumferential direction and the outer circumferential direction of the disk 1, by performing this operation, the dimple slip directions can be aligned. Therefore, the generated off-track amount between heads can be halved. As a result, once 5μ
m, the off-track amount between heads can be reduced to 5 μm or less again.
ms.

In this embodiment, in order to correct the off-track amount between heads caused by dimple slip,
Although CSS was performed, even if it is not CSS, the same effect can be obtained if the rotational speed of the disk is reduced and the head slider 3 is dragged at an angle to the disk 1.

Further, in the present embodiment, the correction is performed based on the number of times the head switching time becomes longer than the skew time. However, the head switching time is checked, and the correction is performed when the head switching time becomes longer than a predetermined time. You may do it. For example, the correction is performed when the head switching time exceeds the skew time so that the disk does not need to be rotated extra. Alternatively, the correction may be made if the head switching time exceeds 0.9 times the skew time because the head switching time is longer than the skew time when the head switching time becomes longer than the skew time.

If the frequency of correction is high, it takes a long time for correction, and recording / reproduction cannot be performed during that time, so that the average recording / reproduction time may be rather delayed. For this purpose, it may be set so that correction is not performed continuously.

Further, even if the head slider 3 and the disk 1 are not brought into contact with each other, for example, the head slider 3 may be hit multiple times against one of the stoppers (not shown) on the outer peripheral side or the inner peripheral side,
The same effect can be obtained by reducing the impact force to a force that causes dimple slip even if the spring force is initially zero, and gradually reducing the force.

Another embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a plan view of a magnetic disk drive on which the load / unload mechanism 4 is mounted. The configuration of the head support mechanism is substantially the same as that of FIG. 3, but a lift tab 13 having a curved surface is provided at the tip of the load beam 8 for loading / unloading.

When a load / unload command is executed, the lift tab 13 moves up and down while being in contact with the ramp 14 on the outer peripheral side of the disk 1. Gimbal tongue 6
On both sides, hooks 15 are provided for engaging the load beam 8 in the unloading process and forcibly separating the head slider 3 from the disk 1. Head slider 3
A so-called negative pressure type head slider utilizing negative pressure is generally used in order to make the floating gap with the disc 1 substantially constant at the inner, middle and outer circumferences.

FIG. 5 is a side view of the head support mechanism 4 during the unload operation. FIG. 5A shows the head slider 3.
The head slider 3 is floating above the disk 1 with a predetermined gap, and the dimple 9 is in contact with the gimbal tongue 6 at this time. (b) is a diagram at the time of unloading. When an unloading instruction is executed, the actuator 12 moves the head support mechanism 4 to the outer peripheral side of the disk 1. Then, the lift tab 13 contacts the ramp 14,
The lift tab 13 rides on the ramp 14.

However, since a negative pressure acts between the head slider 3 and the disk 1, the head slider 3
The lift tab 13 and the leading end of the load beam 8 are not deflected immediately from the surface, so that a so-called lift delay occurs. When the lift is further performed and the lift amount of the lift tab 13 reaches a certain amount, the dimple 9 and the gimbal tongue 6 are separated. At this time, a negative pressure acts between the flying surface of the head slider 3 and the disc 1 in the height direction, but almost no force acts in the in-plane direction of the disc 1.

Accordingly, the reaction force acting on the gimbal arm 7 causes the gimbal tongue 6 to be pulled back to a substantially neutral position. Thereby, the pivot slip can be corrected. When the lift further proceeds, as shown in FIG.
Since the lift tab 13 is lifted in a state where the load beam 8 is in contact with 5, the head slider 3 is forcibly peeled off from the surface of the disk 1.

As described above, dimple slippage can be corrected by executing the unload operation.

As another embodiment of the present invention, the head slider 3 floats on the disk 1 for a long time, dust and the like adhere to the flying surface of the head slider 3 to increase the flying height, and the recording / reproducing characteristics deteriorate. A method for solving the problem that occurs and degrades the input / output characteristics of the disk device will be described.

The number of times of input / output per unit time of the disk device becomes equal to or less than a predetermined number, or an input error /
When an output error occurs continuously and exceeds a predetermined number of times, or when the operation time of a disk device exceeds a predetermined
As in the case of the first embodiment, by rubbing the CSS or the rotation speed of the disk 1 between the head slider 3 and the disk 1, it is possible to remove the deposits on the floating surface and to recover the floating amount to a desired floating amount. ,
The recording / reproducing characteristics are restored, and the input / output characteristics of the disk device are restored.

The operation of lowering the rotation speed of the CSS or the disk 1 is performed, for example, when the number of times of input / output per unit time of the disk device is a predetermined number of times, for example, the number of times of disk device shipping
When the number of recordings becomes 95% or less, or when recording / reproduction cannot be continuously performed more than a predetermined number of times, for example, 5 or more times, the operation time is performed every predetermined time, for example, every 5000 hours. However, this operation is
Since the performance may be degraded due to other causes, the same operation is not repeated three or more times.

Further, when the magnetic disk device using these embodiments is used for an information storage device such as a RAID system, even if the input / output time for recording / reproducing information temporarily drops due to the occurrence of dimple slipping, it will immediately occur. Even if the flying height increases due to long-term operation, the recording / reproducing characteristics deteriorate, and the input / output performance temporarily drops, it can be recovered immediately, and the time for inputting and outputting a certain amount of data can be restored. The short state can be kept long. That is, an information storage device that can maintain high input / output performance for a long time can be realized.

[0042]

According to the present invention, a magnetic disk drive capable of maintaining high input / output performance for a long time can be realized.

Further, by using this magnetic disk device, it is possible to realize an information storage device capable of maintaining high input / output performance for a long time.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating the present invention.

FIG. 2 is a perspective view of a magnetic disk drive.

FIG. 3 is a diagram illustrating details of a head support mechanism.

FIG. 4 is a plan view of a magnetic disk drive equipped with a load / unload mechanism.

FIG. 5 is a side view of the head support mechanism during an unload operation.

[Explanation of symbols]

1 ... disk, 2 ... CSS zone, 3 ... head slider, 4
... head support mechanism, 5 ... outer peripheral side, 6 ... gimbal tongue, 7
... Gimbal arms, 8 ... Load beams, 9 ... Dimples,
10 motor, 11 carriage, 12 actuator, 13 lift tab, 14 lamp, 15 hook.

Claims (7)

[Claims] 1. A disk comprising a disk serving as a recording medium, a head slider for recording / reproducing information on / from the disk, a support mechanism for fixing the head slider, and a motor for positioning and driving the support mechanism. A disk device for rubbing the head slider and the disk when a head switching time of the head slider or a movable time of the disk device becomes equal to or longer than a predetermined time. 2. A disk as a recording medium, a head slider for recording / reproducing information on / from the disk, a support mechanism for fixing the head slider, a motor for positioning and driving the support mechanism, and the disk A load / unload mechanism for keeping the head slider and the head slider in a non-contact state, wherein when the head switching time of the head slider exceeds a predetermined time, or when input / output per head unit time is performed. A disk device for unloading the head slider from the disk when the number of outputs reaches a predetermined number. 3. A disk drive comprising: a disk serving as a recording medium; a head slider for recording / reproducing information on / from the disk; and an actuator for fixing and positioning the head slider. A disk drive for reducing the number of rotations of the disk when the head switching time becomes equal to or longer than a predetermined time. 4. A disk serving as a recording medium, a head slider for recording / reproducing information on / from the disk, a gimbal tongue for fixing the head slider, and a load for supporting the gimbal tongue via a dimple. A magnetic disk device comprising: a beam; and a dimple sliding when the head slider waits for rotation. 5. A disk serving as a recording medium, a head slider for recording / reproducing information on / from the disk, a gimbal tongue for fixing the head slider, and a load for supporting the gimbal tongue via dimples. What is claimed is: 1. A magnetic disk drive comprising a load / unload mechanism for keeping a beam, said disk and said head slider in a non-contact state, wherein said head slider is moved to said disk when rotation waiting occurs in said head slider. Disk unit to be unloaded from 6. A disk comprising a disk as a recording medium, a head slider for recording / reproducing information on / from the disk, a support mechanism for fixing the head slider, and a motor for positioning and driving the support mechanism. An input / output count per unit time of the disk device is equal to or less than a predetermined count, or an input error / output error is continuously generated and is equal to or greater than a predetermined count. A disk device that rubs against a disk. 7. A disk serving as a recording medium, a head slider for recording / reproducing information on / from the disk, a gimbal tongue for fixing the head slider, and a load beam for supporting the gimbal tongue via dimples. 7. An information storage device using a plurality of magnetic disk devices each having: a motor for fixing the load beam and positioning and driving the head slider. 7. The magnetic disk device according to claim 1, wherein An information storage device using a magnetic disk device.