Dynamic magnetic information storage or retrieval – General recording or reproducing – Specifics of biasing or erasing
Reexamination Certificate
2000-02-07
2003-05-27
Faber, Alan T. (Department: 2651)
Dynamic magnetic information storage or retrieval
General recording or reproducing
Specifics of biasing or erasing
C360S137000, C361S267000, C361S149000
Reexamination Certificate
active
06570727
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for erasing information recorded on a disk of a magnetic disk device. More particularly, the present invention relates to a method and an apparatus for erasing servo data and test data used in fabrication steps, particularly in repairing steps, of a magnetic recording device.
2. Background Art
Servo data are written in servo data writing steps during the manufacturing process of magnetic disk devices. The manufacturing process also includes writing and testing test data. Defects in the servo data frequently cause disk drives to fail the drive tests. In these cases, generally the disk drive must be disassembled so that any reusable parts can be recovered and so as to avoid the environmental and financial costs of discarding the entire disk device. Recovering the disk is particularly important because disks are costly and it is difficult to recycle disks after they have been discarded.
Any servo or test data on the recovered disks generally must be erased before the disks can be incorporated into a new disk drive so as prevent interference with the new servo and test data that will be recorded on the disk.
Several conventional methods for erasing information recorded on a disk have been used including:
1. DC erase by a servo track writer;
2. DC erase by a dedicated erasing device; and
3. Erase by an erasing bar.
In servo track writer DC erase methods, information on the disk is erased by DC signals applied to a servo track writer write head. Although this method can completely erase the information on the disk, it is unsuitable for a mass production process since servo track writers are costly and large sized. Also servo track writer DC erase methods are comparatively slow.
Dedicated erasing devices provide a lower cost alternative to servo track writer DC erase methods. However, conventional dedicated erasing devices are generally too slow to be suitable for mass production processes.
In DC erase methods using an erasing bar, a bar on which a permanent magnet is mounted is inserted between the rotated disks to erase all of the information on the disks, as described in Japanese published patent application H7-29106. A problem with conventional erasing bar DC erase methods is that while they may be used with disk devices having a flat type base as shown in
FIG. 2
, the methods are not readily used with disk devices having a bath tub type base as shown in
FIG. 3
since a space for inserting the erasing bar from a lateral direction is required. That is, in a disk device
200
shown in
FIG. 2
, a spindle motor
204
is mounted on a flat type base
202
, and magnetic disks
206
and
208
are mounted on the spindle motor
204
. Information written on disks
206
and
208
is erased by removing a top cover, not shown, and inserting the erasing bar
210
from a side of the disk device. In contradistinction, in the disk device
300
shown in
FIG. 3
, a spindle motor
304
is mounted on a bath tub type base
302
, and magnetic disks
306
and
308
are mounted on the spindle motor
304
. Even if a top cover, not shown, is removed, the sides of the disks are still covered by the bath tub type base
302
, thereby preventing insertion of erasing bar
310
.
A further drawback of DC erase methods using erasing bars is that the vertical position of the erasing bar must be precisely controlled due to the narrow spacing of the disks, and positional deviations can damage the disks. Furthermore, the space between disks is decreasing as a result of efforts to increase the storage capacity, and reduce the size of disk drives.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and an apparatus for erasing information recorded on disks in magnetic disk devices irrespective of the shape of the base of the disk device.
Another object of the present invention is to provide a method and an apparatus for rapidly and reliably erasing information recorded on disks in magnetic disk devices.
A further object of the present invention is to provide an inexpensive system for erasing information on disks, while ensuring the disk device does not contact the magnets.
A method of erasing information recorded on a disk recording medium in a magnetic disk device comprising the disk recording medium, a motor for rotating the disk recording medium, a base attached to the motor, and a magnetic head, according to one embodiment of the present invention comprises generating a magnetic field outside of the magnetic disk device, and inserting the magnetic disk device into the magnetic field, wherein the magnetic field passes through the base to erase information recorded on the disk recording medium.
An apparatus for erasing information recorded on a disk recording medium in a magnetic disk device comprising the disk recording medium, a motor for rotating the disk recording medium, a base attached to the motor, and a magnetic head, according to one embodiment of the present invention comprises: a magnet to generate a magnetic field, and a handler to insert the magnetic disk device into the magnetic field.
REFERENCES:
patent: 3869713 (1975-03-01), Owens, Jr.
patent: 4847727 (1989-07-01), Spaman
patent: 5436857 (1995-07-01), Nelson et al.
patent: 5721665 (1998-02-01), Schultz
Patent Abstract for Japanese application No. 05-175,824, Nec Corp., published on Jan. 31, 1995.*
Patent Abstract for Japanese application No. 60-129,909, Yoshimori, published on Jul. 11, 1985.
Mori Hiroki
Tamura Hitoshi
Faber Alan T.
International Business Machines - Corporation
Kunzler & Associates
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