Dynamic magnetic information storage or retrieval – General processing of a digital signal – Data in specific format
Reexamination Certificate
1998-07-29
2002-10-15
Sniezek, Andrew L. (Department: 2651)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Data in specific format
C360S077080, C360S075000
Reexamination Certificate
active
06466387
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a data recording disk, a disk drive device and a method for writing servo patterns on a data recording surface of a rotating data recording disk, and more particularly to a method, data recording disk and disk drive having servo patterns that improve efficiency of head positioning and data storage.
2. Description of Related Art
A giant magneto resistive (GMR) head has been developed as a next generation read/write head of a hard disk drive device. The GMR head can generate an output signal which is larger than an output signal generated by a prior magneto resistive (MR) head. The capability of generating the large output signal causes a reduction of a head width of the GMR head.
The GMR head is fabricated by the fabrication process of the MR head, and hence a head width of the GMR head is determined by a tolerance of the fabrication process of the MR head. It is assumed that the head width of the prior MR head is 2 &mgr;m, (1 &mgr;m=10
−6
m), the head width of the GMR head is 1 &mgr;m, and the tolerance of the fabrication technology of the MR head is 0.4 &mgr;m. Since the tolerance of the 0.4 &mgr;m is applied to both the MR head and GMR head, the head width of the MR head is 2 &mgr;m±0.4 &mgr;m, that is, the track width of the MR head varies from 1.6 &mgr;m to 2.4 &mgr;m, and a variance of the head width is 20%. The head width of the GMR head is 1 &mgr;m±0.4 &mgr;m, that is, the head width of the GMR head varies from 0.6 &mgr;m to 1.4 &mgr;m, and a variance of the head width is 40%. In this manner, the variance of the head width of the MR head is 20%, while the variance of the head width of the GMR head is 40% which is larger than that of the MR head.
An uniform track pitch is used in the track arrangement of the prior MR technology. A track pitch is a distance between a track center of one track and a track center of the next track.
If the uniform track pitch of the MR head is used for the GMR head, the following first problem, as shown in
FIG. 1
occurs. As described above, the head width of the GMR head varies from 0.6 &mgr;m to 1.4 &mgr;m. For simplifying the description, three kinds of the GMR heads
1
,
2
and
3
are shown in
FIG. 1
, i.e., the GMR head
1
has the 1.4 &mgr;m head width, the GMR head
2
has the 1.0 &mgr;m head width, and the GMR head
3
has the 0.6 &mgr;m head width. The track width of all the tracks
1
,
2
and
3
are the same width, i.e., 1.4 &mgr;m, which is the largest width of the GMR head, and the uniform track pitch is used for all the tracks. A gap is provided for separating the adjacent two tracks. And, the center of the GMR heads
1
,
2
and
3
are aligned to the track center of each track, respectively. It is apparent that useless or wasted space exists between the GMR heads
1
and
2
, and between the GMR heads
2
and
3
.
The following second problem occurs with respect to the servo patterns provided in the track. The servo patterns A and B are written to define the tracks, and read by the head to generate a feedback signal which is supplied to a hard disk control device. The detail of the servo patterns A and B are shown in FIG.
4
(B) and (C). The servo pattern A has alternately arranged opposite magnetization direction, and the servo pattern B has an uniform magnetization direction. The hard disk control device responds to the feedback signal to position the center of the head on the track center. It is assumed that the GMR heads
1
,
2
and
3
are shifted from the track center by a distance of 10% of the track pitch, as shown by the dashed line in FIG.
1
. For example, it is assumed that the track pitch=track width×1.1=1.4 &mgr;m=1.1×1.6 &mgr;m, and the shift distance=track pitch×0.1=0.16 &mgr;m. In this case, the GMR heads
1
,
2
and
3
are shifted with respect to the servo pattern B, and the variation of the levels of the feedback signals sensed by the GMR heads
1
,
2
and
3
are as follows.
In the case of the GMR head
1
of the 1.4 &mgr;m head width: 0.16 &mgr;m/1.41 &mgr;m=0.114. That is, the level of feedback signal is reduced by 11.4%. In the case of the GMR head
2
of the 1.01 &mgr;m head width: 0.16 &mgr;m/1.0 &mgr;m=0.16. That is, the level of feedback signal is reduced by 16%. In the case of the GMR head
3
of the 0.6 &mgr;m head width: 0.16 &mgr;m/0.6 &mgr;m=0.267. That is, the level of feedback signal is reduced by 26.7%.
The variation of the levels of the feedback signal sensed by the prior MR head of 2.4 &mgr;m head width, the prior MR head of 2.0 &mgr;m head width, and the prior MR head of 1.6 &mgr;m head width are, as follows. It is assumed that the track pitch=track width×1.1=2.4 &mgr;m×1.1=2.6 &mgr;m, and the shift distance=track pitch×0.1=0.26 &mgr;m.
In the case of the MR head of the 2.4 &mgr;m head width: 0.26 &mgr; m/2.4 &mgr; m=0.108. That is, the level of the feedback signal is reduced by 10.8%. In the case of the MR head of the 2.0 &mgr;m head width: 0.26 &mgr;m /2.0 &mgr;m=0.13. That is, the level of the feedback signal is reduced by 13%. In the case of the MR head of the 1.6 &mgr;m head width: 0.26 &mgr;m/1.6 &mgr;m=0.163. That is, the level of the feedback signal is reduced by 16.3%.
In this manner, when the head is shifted by the distance of track pitch multiplied by A, the level of the feedback signal of the MR head to the hard disk control device varies from 10.8% to 16.3%, while the level of the feedback signal of the GMR head to the hard disk control device varies from 11.4% to 26.7%.
The range of the variation of the feedback signals to the hard disk control device should be small, since if the range of the variation becomes large, undesirable phenomenon, such as an oscillation of the entire servo system may occur.
It can be seen then that there is a need for a method, data recording disk and disk drive that eliminates useless or wasted space on a data recording disk.
It can also be seen that there is a need for a method, data recording disk and disk drive that provides a track pitch that varies depending o the track width.
It can also be seen that there is a need for a method, data recording disk and disk drive that provides a uniform level of variation I the feedback signals.
SUMMARY OF THE INVENTION
To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a data recording disk that includes a first data recording surface and a second data recording surface, wherein a track pitch of adjacent data recording tracks of the first data recording surface differs from a track pitch of adjacent data recording tracks of the second data recording surface.
A data recording disk according to the present invention includes a first data recording surface and a second data recording surface, wherein the number of data recording tracks of the first data recording surface differs from the number of data recording tracks of the second data recording surface, and the a gap width between the data recording tracks of the first data recording surface differs from a gap width between the data recording tracks of the second data recording surface.
A data recording disk according to the present invention includes a first data recording surface and a second data recording surface, wherein the number of data recording tracks of the first data recording surface differs from the number of data recording tracks of the second data recording surface.
A disk drive device according to the present invention includes data recording surfaces on a rotating data recording disk, each of the data recording surfaces is provided with a read/write head, wherein the number of data recording tracks of a first data recording surface differs from the number of data recording tracks of a second data recording surfa
Kobayashi Keiji
Ogasawara Kenji
Yanagisawa Hiroshi
Altera Law Group LLC
Sniezek Andrew L.
LandOfFree
Data recording disk and disk drive device for reducing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Data recording disk and disk drive device for reducing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Data recording disk and disk drive device for reducing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2992391