JPH06282930A - Control method for magnetic disk device - Google Patents

Abstract

(57) [Abstract] [Purpose] Detects signs of failure such as head crash during operation without causing enlargement of structure and lowering of operating efficiency, and ensures occurrence of fatal failure such as head crash. (EN) Provided is a magnetic disk drive control technique for preventing the above. A contact detection circuit 50 for detecting contact between the head 1 and the disk 2 by an energization phenomenon is provided, and the contact detection cycle and the rotation cycle of the disk 2 are matched or non-matched to intervene by intentionally executing CSS. Objects are removed, and operations such as contact detection position registration and access prohibition are performed to reliably avoid obstacles such as a fatal head crash.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive control technique, and more particularly to a technique effective for avoiding a fatal failure such as a head crash in the magnetic disk drive.

[0002]

2. Description of the Related Art In a magnetic disk device, a basic structure is aluminum or glass as a substrate material, a magnetic film is formed on the surface of the substrate to magnetically retain information, and the surface of the disk is rotated by rotating the magnetic disk. Slightly
It is composed of a head made of a material whose mainstream is a ferrite or a metal thin film for floating or writing information on or from the magnetic disk while keeping a space of about 0.1 micron. The magnetic disk and the head have a case (HD
A: Head Disk Assembly).

Therefore, the contact resistance between the head and the magnetic disk is not only directly related to the life of the device, but also the stored information cannot be locally read out depending on the condition of the failure, or if it becomes worse, it is stored in the device. All of the existing information may not be readable, and even today, in the field of magnetic disk drives that are becoming smaller, larger in capacity, higher in density, and faster in speed, the field of application has been expanded and the obstacle The impact of will have an important social position.

The initial phenomenon of such an important obstacle is mainly due to the collision between the head and the magnetic disk. This is because when the head floats and the surface roughness accuracy varies during the manufacturing process of the magnetic disk, the protrusions hit the head slider surface or are removed during the cleaning process of the parts mounted inside the HDA. If dust that could not be filled is present between the head and the magnetic disk,
The head is destroyed by the collision, resulting in the above-mentioned obstacle. Further, this collision phenomenon has a property that, once it occurs, it is accelerated by the broken pieces and dust emitted from both sides due to the collision.

In the future, further high density recording and large capacity will be indispensable, and the space (flying space) between the head and the magnetic disk tends to become narrower. Conventionally, as a means for solving this problem, The following measures have been considered.

The first conventional example is Japanese Patent Laid-Open No. 2-312059.
As disclosed in Japanese Patent Publication No. JP-A-2003-96, the resistance value at the time of contact and non-contact on the slider surface of the head and the magnetic disk surface is stored in the device in advance, and the current measured value is compared with the stored value. The device is stopped when it is determined to be in contact.

A second conventional example is Japanese Patent Laid-Open No. 2106101/1990.
As disclosed in Japanese Patent Publication, a vibration detecting element is provided on the upper surface of the head slider to determine whether or not the slider surface of the head is in contact with the magnetic disk surface. When it is determined that the contact is made, the apparatus is stopped. , Is.

[0008]

In order to prevent the above-mentioned important obstacles, when a collision between the head and the magnetic disk, which is the initial cause, is detected, it is detected and further deterioration is prevented even after the detection. And maintaining normal operation is an important issue.

The problems of the conventional example will be described below.

In the contact detection method of the first conventional example, the judgment is made by comparing the resistance value when contacting and when not contacting. However, inside the HDA, dust or aging that cannot be completely removed in the component cleaning process is used. For example, the quality may change and dust may be generated, and the resistance may change even when it floats inside until it is captured by the filter and is interposed between the head and the magnetic disk.

In this case, the dust has at least two properties, one of which is attached to the head or the magnetic disk and causes a serious trouble, and the other of which is temporarily interposed. There are some that go out of the magnetic disk at the next moment and do not cause a serious obstacle. Even in the latter case, if the device is simply stopped, the operation will be unnecessarily increased, which causes a problem in actual operation.

When a vibration detecting element is provided on the upper surface of the slider as in the second conventional contact detecting method to judge the contact between the slider surface of the head and the magnetic disk surface,
Considering the detection accuracy, the detection element must be mounted on the head support surface, but the current head support surface is 3.5
Since it is about mm square and the vibration detection element is about 1.5 mm square at the minimum, if you consider the place where it interferes with the load arm that supports the head, it is not possible to secure a mountable space, further downsizing, large capacity In a magnetic disk device for which higher speed, higher density recording, and higher speed are required, there is a concern that it may be an obstacle to narrowing the magnetic disk mounting interval.

An object of the present invention is to detect the occurrence of a failure such as a head crash during operation without causing an increase in size of the structure and a decrease in operating efficiency, and to ensure the occurrence of a fatal failure such as a head crash. Another object of the present invention is to provide a control technology of a magnetic disk device that can prevent the above.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0015]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

That is, the control method of the magnetic disk device of the present invention is such that a rotatable disk-shaped magnetic disk for recording information, a head for recording and reproducing information on the magnetic disk, and a magnetic field of the head. Head driving means for moving and positioning the disk in the radial direction,
Position detecting means for detecting a radial position of the head with respect to the magnetic disk, an information recording / reproducing circuit for recording / reproducing information by the head, and a housing for accommodating at least the magnetic disk, the head and the head driving means in a sealed state,
In a magnetic disk device including a filter for trapping suspended dust in the housing, contact detection means for detecting a contact state between the head and the magnetic disk is provided by a contact phenomenon, and the magnetic disk is detected when the contact is detected. When the first operation of retracting the head from the upper contact detection position and recording the contact detection position does not match the generation cycle of the contact detection signal obtained from the contact detection means and the rotation cycle of the magnetic disk, the head is rotating. When the generation cycle and the rotation cycle coincide with the second operation of intentionally bringing the magnetic disk and the head into contact with each other in a specific area on the magnetic disk and accelerating the atmosphere circulation in the housing, the contact detection position Reposition the head to the magnetic disk to check again for contact, and if contact is detected again, set the contact detection position. It is obtained to perform a third operation of the access prohibition.

[0017]

According to the above-described method for controlling a magnetic disk drive of the present invention, when contact between the head and the magnetic disk occurs, which is one of the signs of a head crash that is an important obstacle,
When the contact detection position is recorded and the generation cycle of the contact detection signal and the rotation cycle of the magnetic disk do not match, depending on the generation cycle or the like, it is caused by, for example, floating dust or foreign matter adhering to the head side. It is determined that the magnetic disk and the head are intentionally brought into contact with each other in a specific area such as a CSS area on the rotating magnetic disk to remove foreign matter attached to the head, and to accelerate the circulation of the atmosphere in the housing. When the generation cycle of the contact detection signal coincides with the rotation cycle, the head is positioned at the contact detection position to reconfirm the contact with the magnetic disk, and the contact is made again. If detected, an operation is performed to prohibit access to the contact detection position.

As a result, the operating efficiency of the magnetic disk device is improved as compared with the case where the device is simply stopped at the time of contact detection. Further, since the contact state between the head and the magnetic disk is detected by the energization phenomenon between the head and the magnetic disk, it is not necessary to add a device having a large size such as a head, and the device may be increased in size due to the addition of the device. Absent.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A control method for a magnetic disk drive according to an embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a conceptual diagram showing an example of the principle of the control method of the magnetic disk device of this embodiment, and FIG. 2 is a sectional view showing an example of the configuration of the magnetic disk device of this embodiment. Further, FIG. 3 is an explanatory diagram showing a part of the extracted structure.

First, the configuration of the magnetic disk drive of this embodiment will be described with reference to FIG.

A disc 2 for holding information magnetically, which has a magnetic film formed on the surface of aluminum as a substrate material, is fixed by a disc clamp 4 to a spindle motor 7 for rotationally driving the disc. It is equipped with an electromagnetic coil that levitates on the surface of this rotationally driven disk 2 while keeping a constant space of only about 0.1 micron and magnetically writes or reads information to convert information into a magnetic field. Head 1 and load arm 1 holding the head 1
9, a head arm 9 for fixing the head 1, a carriage 11 for accurately positioning them on the surface of the disk 2, and a head clamp 12 for fixing the head arm 9 to the carriage 11, which are VCMs. It is driven and positioned by the coil 13 and the voice coil motor 14 (VCM).

A signal for reading and writing of the head 1 is transmitted through the head arm 9 by the head thin wire 23 and fixed at several places and connected to the flexible printed circuit board 22 (FPC) to control the signal for reading and writing of the head 1. 21 (see FIG. 5) and is connected to a main board 26 provided outside the HDA for controlling the apparatus. Also V
The drive current of the CM coil 13 is also connected to the main board 26 outside the HDA through the FPC 22. Spindle motor 7, carriage 11, VCM 14 are base 1
It is fixed to No. 5 and is sealed with a cover 16 via a packing 27 to shut off from the outside air. The HDA configured as described above interferes with the magnetic field by inclusions entering the HDA internal space in order to accurately process the signal in the operation state of writing or reading information between the head 1 and the disk 2. Since it must be kept clean since it must not always be provided, a filter 25 (see FIG. 5) is provided to capture the internal dust by the air circulation inside the HDA generated by the rotation of the disk 2.

Since the magnetic disk device is required to have a small size, a large capacity, a high density recording, and a high speed, a plurality of disks 2 are mounted in order to obtain a storage capacity. Since it exists, a disk spacer 3 is provided between the disks 2 and a head spacer 1 is provided between the head arms 9 and 9.
By setting 0, the interval is kept constant.

In this embodiment, the head crush prevention function is activated by detecting the contact between the head 1 and the disk 2 due to the energization phenomenon on the surfaces of the head 1 and the disk 2. Therefore, the energization phenomenon occurs between the slider surface of the head 1 and the disk 2. Must be detected by contact with. Therefore, the configuration of the contact detection circuit 50 will be described below with reference to FIG.

The contact detection circuit 50 of the present embodiment uses a lead wire 6 connected to the disk 2 side and a thin wire 18 connected to the head 1 side to connect a desired direct current between the head 1 and the disk 2. It is composed of a power supply 51 for applying a voltage, a resistance element 52 (R) for adjusting a current value, a voltmeter 53 for observing a change in potential, and the like. If the material of the slider of the head 1 is a conductor, the thin wire 18 on the head 1 side of the detection circuit may be directly connected, but if the material of the slider is a non-conductor or the detection position (danger area) range is In order to detect accurately, for example, as shown in FIG.
It is also possible to use a structure in which a conductive member 17 or a conductor-treated film is applied to a part of the slider surface closest to the surface of the disk 2 facing the disk 2 and the area is set as small as possible to set the dangerous area in a narrow range. A thin wire 18 electrically connected to this is provided, and it is guided to the head arm 9 together with the thin head wire 23 and connected to the main substrate 26.

Wiring examples from the thin wire 18 to the main board 26 are shown in FIGS. FIG. 5 shows the head 1 on the surface of the disk 2.
An example of a magnetic disk device adopting a rotary type in which the transfer method of FIG. In FIG. 6, the carriage 1 is the transfer method of the head 1.
An example of a magnetic disk device adopting a linear type for performing linear motion of No. 1 will be shown. When the load arm spacer 28 of the head 1 is attached to the head arm 9, the load arm spacer 28 of the head 1 and the head arm 9 are electrically insulated from each other by adhering the load arm spacer 28 to the head arm 9 through the head insulating film 24. This insulating location may be provided anywhere as long as the circuit configuration is such that the slider surface of the head 1 and the disk 2 are brought into a conductive state by contact with each other. It is desirable that the head insulating film 24 is thin in terms of mounting space efficiency.

Here, the structure of the spindle motor 7 is an outer rotor structure of a shaft rotation type as shown in FIG. 2 (a structure in which a motor coil 29 and a rotor 31 to which a motor magnet 30 is fixed are provided outside the HDA. In the case of 1), the spindle ground 8 is fixed to the base 15 by providing a contact portion at the center of rotation of the rotor 31. When the spindle motor 7 has a shaft-fixed in-hub structure as shown in FIG. 4 (a structure in which the motor coil 29 and the motor magnet 30 are provided inside the hub of the spindle motor 7), the bearing 20 for rotating the hub is used. The detection accuracy can be improved by reducing the electric resistance between the disk 2 and the base 15 by using a conductive grease.

Further, the lead wire 6 is provided at an arbitrary position on the base 15.
To be electrically connected. By applying a voltage between the lead wire 6 and the thin wire 18 connected to the head 1, the head 1
The contact between the slider surface and the disk 2 surface is detected. The detection voltage can be read or written by the device (R
It is applied when in the EADY state. This applied voltage condition is such that it does not interfere with the operation of simultaneously writing or reading information when energized.

For example, in the model of FIG. 1 as an example, the disk 2 is a general sputter disk having aluminum as a substrate material and a surface coated with a lubricant, and is gradually lowered from the normal flying height of the head 1. When the head 1 is intentionally brought into contact with the surface of the disk 2 and there is no inclusion between the head 1 and the surface of the disk 2, R (resistance value) is about 500 ohms, and the power supply voltage is about 2 volts. In the applied state, an energization phenomenon of about 2 mA can be confirmed between the slider surface of the head 1 and the surface of the disk 2, and the voltage drop amount at that time is about 1 volt. Next, set the flying height to 0.0
When it is increased by about 1 micron, the energization phenomenon disappears. Further, when there is an inclusion between the head 1 and the disk 2 and the inclusion is attached to the head 1, energization is started with a higher flying height than when there is no inclusion, and then CSS is applied.
By performing the (Contact Start Stop) operation, the state without inclusions is reproduced when the above experiment is performed again.

From the above results, normally, when the apparatus writes or reads information, the current flowing through the coil of the head 1 is about 20 to 50 milliamperes, so that the information is simultaneously written or read when energized. This does not hinder this, and even if a non-conductive lubricant is applied to the surface of the disk 2, it is negligible and there is no problem. In addition, the amount of voltage drop is about 1/2 of the steady application, so that it can be sufficiently detected.

In the case of this embodiment, the current is applied to the head 1 when the slider surface of the head 1 and the surface of the disk 2 come into contact with each other.
From the thin wire 18 connected to the lead wire 6 of the base 15 to the spindle member 7 of the disk 2 which is in contact with the conductive member 17 or the conductor treatment film provided on the slider surface.

Next, the slider surface of the head 1 and the disk 2
The command operation of the head crash prevention function after detecting the contact between the both due to the energization phenomenon on the surface of will be described with reference to FIGS. 7, 8 and 9.

When the contact is detected by the drop of the applied voltage of the contact detection circuit 50, the detected position information is once stored in a specific area of the disk 2 or the RAM. If the device state at the time of contact detection is an operation of writing or reading information, the information is also stored once on the disk 2 or in the RAM. The information stored once is used in the subsequent operations (A information in FIG. 8).

Next, after contact detection, the head 1 is immediately withdrawn from the contact detection position (dangerous area), and the spindle motor 7
3 times or more (Head 1 slider contacts 3 times or more)
Transfer to a safe area so that it is not at the contact detection position. The dangerous area is a shaded area in FIG. 7, and the safe area is a range other than the dangerous area. Here, the cause of contact detection is floating dust or dust adhering to the disk 2 or the head 1.
Determine whether it is dust adhering to the or other causes or not as follows. That is, this judgment is made by the spindle motor 7 at the time of detection after the head 1 is transferred to the safe area.
It is performed by checking whether the detection signal interval is synchronized with the rotation speed of the spindle motor 7 according to the rotation speed and the detection signal interval.

When synchronized, T1 and T2 shown in FIG.
When the times are the same, it is determined that the dust is attached to the disk 2 in this case, and it is determined as another cause in other cases.

Next, in the case of non-synchronization as described above, it is judged that it is either floating dust or dust adhering to the head 1, and as a measure for removing the floating dust, the rotation speed of the spindle motor 7 is increased to circulate air in the HDA. The CSS operation is performed as a countermeasure for the operation of capturing the suspended dust by the filter 25 by the acceleration and the removal of the dust adhering to the head 1. The subsequent operation is the same as the operation when the contact detection cycle is synchronized with the rotational speed of the spindle motor 7, and is as follows.

Next, the head 1 is positioned at the contact detection position to reproduce the operating state of the apparatus when the contact is detected. When the result of the re-operation is normal and no contact is detected, it is determined that the temporary operation has no effect on the subsequent operation, and the information once stored in the specific area on the disk 2 or the RAM at the time of the first detection. Is erased from the disk 2 or the RAM, and this function ends.

When the result of the re-operation is normal and the contact is detected, it is judged that there is a sign of a serious failure, and the dangerous area on the disk 2 is made unusable in the subsequent operations.
D registration and control so that the slider surface of the head 1 does not hit the detection position when the head 1 is transferred, and the information once stored on the disk 2 or RAM at the time of the first detection is this dangerous. Save for later use as an alternative to the area.

When the result of the re-operation is not normal and the operation is the writing operation at the time of the first detection, the operation is performed so that the slider surface of the head 1 does not hit the detection position in the subsequent transfer of the head 1 through the dangerous area. The information once stored on the disk 2 or the RAM at the time of the first detection is stored for later use as a substitute for this dangerous area.

When the result of the re-operation is not normal and the operation is read at the first detection, the operation is performed so that the slider surface of the head 1 does not hit the detection position in the subsequent transfer of the head 1 through the dangerous area as described above. If the information stored on the disk 2 or in the RAM at the time of the first detection is normal, it is saved for later use as a substitute for this dangerous area and is important to the host device if it is not normal. A warning indicating a failure is issued and this function ends.

An example of avoiding the contact detection position (dangerous area) in the subsequent movement and positioning operation of the head 1 by the command operation of the head crash avoidance control as described above is shown in FIG.
Shown in. The dangerous area is at least twice the width X of the head 1 in the radial direction of the disk 2, the width Y of the head at least 1 after the contact detection position in the circumferential direction, and the width of the head 1 Y before the contact detection position. It is an oval range consisting of a surplus length Z from the head 1 positioning speed.

As described above, when the contact between the head 1 and the disk 2, which is a sign of a serious failure such as a head crash, occurs, the contact phenomenon is accurately detected, and the cause of the contact is determined according to the cause of the contact. It is possible to take optimal measures such as removing foreign matter and prohibiting access to the contact detection position, and prevent the contact between the headphone 1 and the disk 2 from becoming a fatal obstacle such as head crash. It is possible to maintain normal operation as much as possible.

[0044]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

According to the magnetic disk drive control method of the present invention, the structure is not enlarged and the operating efficiency is not reduced.
The effect of detecting a failure such as a head crash during operation and reliably preventing the occurrence of a fatal failure such as a head crash is obtained.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of the principle of a control method of a magnetic disk device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an example of the configuration of a magnetic disk device in which a method of controlling a magnetic disk device according to an embodiment of the present invention is implemented.

FIG. 3 is an explanatory diagram showing a main part of a magnetic disk device in which a method of controlling a magnetic disk device according to an embodiment of the present invention is implemented.

FIG. 4 is a schematic cross-sectional view showing a modified example of a motor structure in a magnetic disk device in which a method of controlling a magnetic disk device according to an embodiment of the present invention is implemented.

FIG. 5 is a schematic cross-sectional view showing an example of a head drive system in a magnetic disk device in which a method of controlling a magnetic disk device according to an embodiment of the present invention is implemented.

FIG. 6 is a schematic cross-sectional view showing an example of a head drive system in a magnetic disk device in which a method for controlling a magnetic disk device according to an embodiment of the present invention is implemented.

FIG. 7 is a conceptual diagram showing an example of an operation of a control method for a magnetic disk device according to an embodiment of the present invention.

FIG. 8 is a flow chart showing an example of the operation of the control method of the magnetic disk device according to the embodiment of the present invention.

FIG. 9 is a diagram showing an example of the operation of the method of controlling the magnetic disk device according to the embodiment of the present invention.

[Explanation of symbols]

 1 Head 2 Disc 3 Disc Spacer 4 Disc Clamp 6 Lead Wire 7 Spindle Motor 8 Spindle Earth 9 Head Arm 10 Head Spacer 11 Carriage 12 Head Clamp 13 VCM Coil 14 Voice Coil Motor 15 Base (Housing) 16 Cover (Housing) 17 Conductive member 18 Fine wire 19 Load arm 20 Bearing 21 CNT substrate 22 Flexible printed circuit board 23 Head fine wire 24 Head insulating film 25 Filter 26 Main substrate 27 Packing 28 Load arm spacer 29 Motor coil 30 Motor magnet 31 Rotor 50 Contact detection circuit 51 Power supply 52 Resistance element 53 Voltmeter

Claims (1)

[Claims] 1. A rotatable disk-shaped magnetic disk for recording information, a head for recording and reproducing information on the magnetic disk, and a movement and positioning operation of the head in the radial direction of the magnetic disk. Head driving means for performing, position detecting means for detecting a radial position of the head with respect to the magnetic disk, an information recording / reproducing circuit for recording / reproducing information by the head, at least the magnetic disk, the head and the head driving In a magnetic disk device including a housing that encloses the means in a sealed state and a filter that traps suspended dust in the housing, a contact that detects a contact state between the head and the magnetic disk due to an energization phenomenon. Providing detection means,
The first operation of retracting the head from the contact detection position on the magnetic disk when the contact is detected and recording the contact detection position, the generation cycle of the contact detection signal obtained from the contact detection means, and the magnetic field A second operation in which the magnetic disk and the head are intentionally brought into contact with each other in a specific region on the rotating magnetic disk and the atmosphere circulation in the casing is accelerated when the rotation cycle of the disk does not match. When the generation cycle and the rotation cycle match, the head is positioned at the contact detection position to reconfirm the contact with the magnetic disk, and if contact is detected again, the contact detection is performed. And a third operation of prohibiting access to a position, the method of controlling a magnetic disk device.