Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
1999-03-18
2001-10-23
Sniezek, Andrew L. (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S069000, C360S078040
Reexamination Certificate
active
06307703
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to magnetic disk apparatuses in which a magnetic disk is loaded and used, and more particularly, to a magnetic disk apparatus which reduces abrasion caused by a head on a disk surface.
2. Description of the Related Art
Magnetic media such as floppy disks have been used in magnetic disk apparatuses for recording computer data. In recent years, magnetic media with high capacities have been introduced.
In a conventional magnetic disk apparatus, when data is recorded into or reproduced from a medium, a head contacts the medium while the medium is rotating. Even after data recording or reproduction is finished, the head continues to contact the rotating medium.
Therefore, in some magnetic disk apparatuses for high-capacity media, when data recording or reproduction is not performed for a predetermined period of time, the head is moved to a position where a scratch on a medium causes no problem, namely, to an area not to be used on the disk, for example, to the innermost or the outermost side of the disk.
In such a conventional magnetic disk apparatus, however, when data recording or reproduction into or from a medium is requested from the host computer after the head is moved to an area not to be used on the disk, it takes a long time to perform recording or reproduction. To solve this problem, if the head is retracted after a longer time elapses, the probability that the medium will become abraded increases.
In other words, as shown in
FIG. 4
, even when data is not recorded or reproduced, a head
4
is driven by a driving section
20
that supports the head to compensate for a positional error, and a current flows into the section. If the head
4
vibrates or a mechanical resonance of the head
4
and a suspension
30
occurs, driving the driving section
20
greatly increases the vibration. As a result, abrasion of the medium
1
occurs.
In some magnetic disk apparatuses for high-capacity media, when data recording or reproduction is not performed, a measure is taken in which the head is reciprocated around the target track in order that the same track is not abraded for a long period.
In such a magnetic disk apparatus, however, although abrasion is averaged on the medium
1
, a response to a R/W command sent from the user is delayed. If the head vibrates by a small amount in order to solve this problem, a quick response is obtained but the effect of abrasion averaging becomes less effective.
As described above, in the conventional magnetic disk apparatus, the probability that the medium abrades increases an, in the worst case, previously recorded data may be damaged. The period in which the medium can be used becomes short and the medium frequently needs to be replaced with a new one to avoid data loss.
An additional problem is that power consumption is large even when data reading or writing is not performed, since the head is being driven.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a magnetic disk apparatus which reduces abrasion of a medium caused by a head as much as possible, which prevents the head from being damaged even if an external impact is applied while data recording or reproduction is not performed, and which reduces power consumption.
The foregoing object is achieved according to the present invention through the provision of a magnetic disk apparatus for controlling a head by servo control, for recording data into or reproducing data from a medium, and for performing tracking, wherein, after data recording or reproduction is stopped, servo control is stopped within a predetermined time to stop a positional compensation output to the head to reduce abrasion of the medium.
In the above apparatus, when a predetermined time elapses after data reading or writing is stopped, servo control for the head is stopped. With this operation, the head is released from a condition in which the head vibrates on a medium due to positional compensation. As a result, abrasion of the disk caused by forced vibration (vibration generated by positional compensation) of the head is suppressed as much as possible.
It is preferred that the above apparatus be configured such that servo data recorded in the medium is monitored while servo control is being stopped, and when the head is moved on the medium longer than a predetermined distance, servo control is activated to start a positional compensation output to the head.
As described above, even while servo is being stopped, since servo data recorded in the medium is always monitored, even if an external impact is applied to the magnetic disk apparatus and the head is moved longer than a predetermined distance, in other words, the head is moved outside an area for data use, the head is immediately driven when the head is moved longer than the predetermined distance, to prevent the head from being damaged by an applied large impact.
Servo control can be performed by a linear motor driving apparatus. With the drive of a linear motor, the head can be moved with very high precision.
When servo control is performed by a linear motor, if an external impact is applied while servo control is being stopped, inertia causes the head to attempt to move a long distance. Since a driving force is applied to the head when the head is moved longer than the predetermined distance as described above, the head is prevented from being damaged.
It is preferred that after the predetermined time elapses, when data recording or reproduction is not performed within a certain time, the head be retracted to the innermost side or the outermost side of the medium.
In this case, even if an external impact is applied, the head will not scratch the section of the medium where data recording takes place.
It is also preferred that the stop/start of servo control is processed by software.
As a result, servo control is implemented by a simple program. As compared with a method in which the head reciprocates around the target track, the size of the program can be made small, and thereby the load of the CPU is reduced.
REFERENCES:
patent: H5-298841 (1993-11-01), None
Moriya Makoto
Wakuda Hiroshi
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Sniezek Andrew L.
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