JPH05210828A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent an accident of head crush caused by dirt of a magnetic head by periodically cleaning the surface of a head of a head loading and unloading system. CONSTITUTION:The time for a period of loading the magnetic head on a magnetic disk surface is measured by a working time measuring means 1. Then, when a power source is inputted, a signal is immediately sent to an accumulated time storage means 2, and afterward, the signal is sent, for instance, every 15 min. Subsequently, whenever the accumulative time is renewed, whether a time interval required for cleaning has elapsed or not is decided by a cleaning time deciding means 3. When it is decided that a prearranged time has elasped, a cleaning means 4 is operated to clean the magnetic head, provided that there is no information write/read command from a host device. When there is the command, the cleaning operation is commenced after the command is finished.

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 using a magnetic head loading / unloading method, and more particularly to a magnetic disk device having a head cleaning function for preventing a head crash.

[0002]

2. Description of the Related Art In a magnetic disk device, when a magnetic disk medium rotates at a high speed, the magnetic head is levitated with a slight gap in order to prevent the magnetic head from coming into contact with the medium and causing abrasion or mechanical damage. .. Most of the magnetic disk devices currently used are fixed disk devices in which the magnetic disk medium is not replaced.

Conventionally, in a fixed disk device, when the magnetic head comes into contact with the magnetic disk medium at the time of stop and starts up, the magnetic head rubs the surface of the medium at first, but when the number of rotations increases, aerodynamic buoyancy causes magnetic force. A method in which the head floats by about 0.2 μm was used. This is called the contact start / stop method. As the recording density of the magnetic disk device becomes higher, the flying height of the magnetic head is decreasing in order to realize the higher recording density, and at present, the head of about 0.1 μm to 0.18 μm has appeared.

In order to stably fly the magnetic head with such a low flying height, the surface of the magnetic disk medium is required to have an extremely flat finish without protrusions. However, if it is too flat, when the magnetic head comes into contact at the time of stop, the magnetic head and the medium are attracted to each other, and if they are forcibly peeled off, the suspension of the magnetic head is deformed and a head crash accident occurs. Has been.

In order to avoid this adsorption, it is necessary to make the medium surface uneven to some extent, and this process is called texture. Therefore, as long as the contact start / stop is used, the low flying height and the adsorption prevention conflict with each other, and it is difficult to realize high density recording. As a solution, instead of the contact start stop method, the head
The load / unload method has begun to be put to practical use. In this method, when the rotation of the magnetic disk medium is stopped, the magnetic head is forcibly lifted by mechanical means so as not to come into contact with it.

[0006]

In the magnetic disk drive using the above-mentioned head load / unload method, the magnetic head and the magnetic disk medium never come into contact with each other. However, even in the conventional contact start / stop type magnetic disk device, dust and lubricant applied to the magnetic disk medium gradually adhere to the surface of the magnetic head and solidify when the power is on for a long time. However, a head crash may occur. The contact start / stop method has a function of scraping off dust and the like adhering to the magnetic head.
The unloading method has a drawback that only dust is attached, and therefore the risk of head crash increases.

[0007]

According to the present invention, there is provided an operating time measuring means for measuring an operating time of a magnetic disk device, a cumulative time storing means for storing a cumulative value of the measured operating time, and a magnetic disk medium for a magnetic head. And a head cleaning means for cleaning the facing surface, and a cleaning for determining whether or not the magnetic head cleaning operation is performed by the head cleaning means when the cumulative value of the operating time stored in the cumulative time storage means exceeds a predetermined value. And a time determination means.

The head cleaning means may be a mechanism for lowering the number of revolutions of the magnetic disk medium and for bringing the magnetic head into contact with the magnetic disk medium, or the head cleaning means sets the magnetic head to an unloading state and magnetically drives the magnetic head. A mechanism for wiping dirt off the surface of the head may be used.

The cumulative time storage means may be a large-capacity capacitor, an IC memory backed up by a battery, or an electrically erasable programmable read only memory (EEPROM).

Further, the operating time measuring means and the cumulative time storage means may be a timer circuit that holds the cumulative value when the voltage at the input terminal is not at a prescribed level, and a power source backup means for this timer circuit.

Further, the cumulative operating time stored in the cumulative time storage means may be recorded in a part outside the user data recording area of the magnetic disk medium.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. The operating time measuring means 1 measures the time during which the magnetic head is loaded (ie, levitated) on the magnetic disk surface. This resolution is a predetermined value, for example, 1
It is set to 5 minutes. Then, immediately after the power is turned on, a signal is sent to the cumulative time storage means 2, and thereafter, a signal is sent every 15 minutes. The cumulative time storage means 2 adds and stores one unit (15 minutes) each time a signal is received from the activation time measurement means. In this case, since a signal is sent immediately after the power is turned on, even if the startup time is 15 minutes or less, it is considered to have been operating for 15 minutes. The accumulated time storage means 2 holds the stored contents even when the power is turned off. Each time the cumulative time is updated, the cleaning time determination means 3 determines whether the time interval required for cleaning has elapsed. When it is determined that the scheduled time has just passed, the cleaning means 4 is operated under the condition that there is no information write / read command from the host device, and the magnetic head is cleaned. When there is a command, the cleaning operation is performed after the completion of the command.

FIG. 2 is a block diagram showing an embodiment of the head cleaning means of the present invention.

The magnetic disk medium 6 is attached to the spindle shaft of the spindle motor 5 and 3600 revolutions / minute (RP
Rotate with M). A magnetic head 7 is provided on each side of the magnetic disk medium 6. The magnetic head 7 attached to the rotary type carriage is driven and positioned by a Pois coil motor 8 on an arbitrary track on the inner and outer circumferences of the magnetic disk medium 6. Next, when the rotation of the spindle shaft stops and when the power is turned off, the magnetic head 7 is lifted by the head load / unload mechanism 9 so as not to come into contact with the disk medium.

When the cleaning time determination means 3 issues a head cleaning command, the control circuit 10 first controls the VCM (voice coil motor) drive circuit 12 to move the magnetic head 7 to the innermost data recording area of the magnetic disk medium 6. Move it outside. Next, the SPM (spindle motor) drive circuit 11 is controlled to apply a brake to reduce the rotation speed from the steady rotation of 3600 RPM to about 500 RPM. The flying height of the magnetic head 7 decreases due to the decrease in the number of revolutions, and the magnetic head 7 comes into contact with the magnetic disk medium 6, so that dirt adhering to the surface is scraped off. Here, if the spindle shaft is stopped, the head may be attracted, so the control circuit 10 returns the rotation speed to 3600 PRM again without stopping the spindle shaft. This operation is repeated a plurality of times to complete the head cleaning.

The head cleaning means of FIG. 2 is a mechanism for lowering the rotation speed of the magnetic disk medium 6 to bring the magnetic head 7 into contact with the magnetic disk medium 6, and can be realized only by controlling the circuit and without any special additional mechanism. Further, although the mechanism is complicated, the magnetic head cleaning means may be a mechanism for wiping dirt off the surface of the magnetic head after the magnetic head 7 is unloaded and moved to the outside of the disk surface.

FIG. 3 is a block diagram showing an example of the cumulative time storage means. In FIG. 3, the IC memory 13 is connected to the power supply backup means 15, and is connected to the power supply via the diode 14. As the power backup means 15 even if the power is turned off, a super large capacity capacitor (so-called super capacitor) or a battery can be used.

Further, as a cumulative time storage means, an electrically erasable programmable read only memory (EE
If PROM) is used, the power supply backup means is unnecessary. Further, although the control becomes slightly complicated, the cumulative time may be recorded in a part outside the user data area of the disk medium.

FIG. 4 is a block diagram showing an example in which the timer circuit 16 and the power source backup means 15 of the timer circuit constitute an operating time measuring means of the magnetic disk device and an operating time accumulated time storing means. In FIG. 4, the timer circuit 16 is configured to cumulatively count the time when the voltage at the input terminal of the STP (stop) signal is equal to or higher than a prescribed level, and hold the accumulated value when the voltage is equal to or lower than the prescribed level. .. Then, when the power is turned off, the STP signal becomes low and the cumulative value of the operating time is held. The RST (reset) input of the timer circuit is a terminal for resetting the initial value of the timer to zero.

A model used for a laptop personal computer such as a 2.5-inch magnetic disk device is often provided with a standby mode or the like for stopping the spindle rotor in order to save power during battery operation. In such a model, the operating time should be the time when the spindle axis is rotating (the time excluding the time in standby mode), not the time when the power is turned on.
It is easy to add a change such as adding a standby mode to the stop condition of the timer circuit shown in FIG. 4, and it is within the scope of the present invention.

[0022]

As described above, in the magnetic disk device of the present invention, the surface of the head of the head load / unload system is regularly cleaned, so that the head slash itself caused by the dirt of the magnetic head is prevented. effective. In addition, since the operating time information of the magnetic disk device can be obtained at the same time, there is an effect that it is useful for MTBF (mean failure interval) data collection and failure analysis.

[Brief description of drawings]

FIG. 1 is a block diagram showing components of the present invention.

FIG. 2 is a block diagram showing an example of cleaning means 4 in FIG.

3 is a block diagram showing an example of a cumulative time storage means 2 of FIG.

FIG. 4 is a block diagram showing another example of the operating time measuring means 1 and the cumulative time storing means 2 of FIG.

[Explanation of symbols]

 1 Working Time Measuring Means 2 Cumulative Time Storage Means 3 Cleaning Time Judging Means 4 Cleaning Means 5 Spindle Motor 6 Magnetic Disk Medium 7 Magnetic Head 8 Voice Coil Motor 9 Head Loading / Unloading Mechanism 10 Control Circuit 11 SPM Drive Circuit 12 VCM Drive Circuit 13 IC memory 14 Diode 15 Power supply backup means

Claims (8)

[Claims] 1. A magnetic disk device in which a magnetic head loads / unloads a magnetic disk medium,
Operating time measuring means for measuring the operating time of the magnetic disk device, cumulative time storage means for storing the cumulative value of the measured operating time, and head cleaning means for cleaning the surface of the magnetic head facing the magnetic disk medium. And a cleaning time determination means for determining whether or not the head cleaning means performs a cleaning operation of the magnetic head when the cumulative value of the operating time stored in the cumulative time storage means exceeds a predetermined value. A magnetic disk device comprising: 2. The magnetic disk device according to claim 1, wherein the head cleaning means is a mechanism for lowering the rotation speed of the magnetic disk medium and for bringing the magnetic head into contact with the magnetic disk medium. 3. The magnetic disk drive according to claim 1, wherein the head cleaning means is a mechanism for removing the dirt on the surface of the magnetic head by setting the magnetic head in an unloading state. 4. The magnetic disk drive according to claim 1, wherein the cumulative time storage means is an IC memory backed up by a large capacity capacitor. 5. The magnetic disk device according to claim 1, wherein the cumulative time storage means is an IC memory backed up by a battery. 6. A programmable read only memory (EEPR) in which the cumulative time storage means is electrically erasable.
4. The magnetic disk device according to claim 1, wherein the magnetic disk device is an OM). 7. The operating time measuring means and the cumulative time storing means are composed of a timer circuit for holding a cumulative value when the voltage at the input terminal is not at a prescribed level, and a power source backup means for the timer circuit. 4. The magnetic disk device according to claim 1, wherein the magnetic disk device is a magnetic disk device. 8. The cumulative value of the operating time stored by the cumulative time storage means is recorded in a part of the user data storage area of the magnetic disk medium.
8. The magnetic disk device according to claim 1.