Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
1999-08-12
2001-10-23
Hindi, Nabil (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S048000
Reexamination Certificate
active
06307704
ABSTRACT:
BACKGROUND OF THE INVENTION
(a). Field of the Invention
The present invention relates to a data recording medium and a data recording/reproducing device and, more particularly, to a technique for positioning control of recording/reproducing heads onto a desired track of a recording medium by using a servo-burst signal.
In a computer system, hard disk drives are widely used for storing a large amount of information. For increasing the recording capacity of the hard disk drive, it is desired to increase the recording density of the recording disk in the circumferential direction (moving direction) as well as the radial direction (direction normal to the moving direction) of the recording disk. The increase of the recording density in the radial direction can be achieved by increasing the track density of the recording disk.
The increase of the tracking density highlights an error due to vibration or thermal expansion in the relative location of the recording/reproducing head with respect to the recording disk in the radial direction. The correction of the position error is generally achieved by using a servo-burst pattern recorded on the recording disk. Specifically, the reproducing head reads the servo-burst pattern, which is then subjected to signal processing by a tracking system of the disk drive for accurately positioning the reproducing head onto the data track.
FIG. 1
shows a part of a conventional recording disk, generally designated by numeral
100
, using a sampled servo-burst scheme. In the recording disk
100
, each data track
11
is periodically divided into a plurality of data blocks
12
in a circumferential direction (U), and a plurality of data blocks
12
arranged in the radial direction (R) from the inner periphery to the outer periphery of the disk forms a data area
10
. A servo-burst area
20
is provided between each adjacent two of the data area
10
. In the servo-burst area
20
, four types of servo-burst signals A, A
−
, B and B
−
are successively recorded in the circumferential direction, wherein each type of servo-burst signals is disposed in a column extending in the radial direction. Signal “A” and signal “B” have an equal length, which is equal to the track pitch “p”, and deviated in the radial direction by p/2 from each other. Signal A
−
and signal B
−
are recorded at the locations where signal A and signal B, respectively, are not recorded, i.e., at the locations where A
−
and B
−
supplement signal A and signal B, respectively. The centers of signals A and A
−
as viewed in the radial direction are aligned with the centers of the gaps between the adjacent data tracks
11
, whereas the centers of signals B and B
−
as viewed in the radial direction are aligned with the centers of the data tracks
11
.
The recording/reproducing device includes a single reproducing head (or a single recording and reproducing head)
31
, which reproduces the servo-burst signals. The reproduced signal provides the amount of displacement of the head with respect to the center of the data track
11
for allowing the recording/reproducing device to control the location of the reproducing head.
In the conventional recording disk
100
having the servo-burst area as described above, the servo-burst signals arranged in the four columns occupy a large area, which reduces the data areas or effective user area in the recording disk.
In addition, with the recent increase of the track density of the recording disk, about 2 kHz is generally required for the response frequency of the servo-burst signal, whereas as high as about 20 kHz is required for the frequency of the servo-burst signal itself. In the disk drive adapted for the high frequency and having a rotational speed higher than 100 rps (rotations per second) or 6000 rpm (rotations per minute), the number of servo-burst signals required in a single rotation ranges 100 to 200. This involves a problem of reduced recording capacity due to the large occupied area for the servo-burst signals and a reduced user area.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a data recording medium having an increased user area and reduced servo-burst areas as well as a recording/reproducing device having such a recording medium, by improving the servo-burst signals used for positioning control and a technique for detecting the servo-burst signals even in the case of a reduced track pitch.
The present invention provides a recording medium including a plurality of data tracks extending in a moving direction of the recording medium and arranged with a track pitch “p” in a normal direction perpendicular to the moving direction, each of the data tracks having a plurality of data blocks arranged in the moving direction, a plurality of the data blocks arranged in the normal direction forms a data area, a servo-burst area disposed between each adjacent two of the data area, the servo-burst area including a periodic servo-burst pattern having a period &lgr;, wherein &lgr;=2p×n/m, given n and m being natural numbers prime to each other, with a relationship n/m<2 therebetween.
The present invention also provide a data recording/reproducing device for recording/reproducing data to/from the recording medium as described above.
More specifically, the data recording/reproducing device includes first and second reproducing heads arranged in the normal direction with a pitch of (2j+1)p, given j being an integer not lower than zero.
Alternatively, the data recording/reproducing device includes first through third reproducing heads arranged in the normal direction so that distances between the first reproducing head and the second reproducing head and between the first reproducing head and the third reproducing head are (2j+1)p and (4k+2)p, given j and k being integers not lower than zero.
Alternatively, the recording/reproducing device includes first through fourth reproducing heads arranged in the normal direction so that distances between the first reproducing head and the second reproducing head, between the first reproducing head and the third reproducing head and between the first reproducing head and the fourth reproducing head are (2j+1)p, (4k+2)p and (41+3)p, given j, k and 1 being integers not lower than zero.
In accordance with the recording medium of the present invention, the area for the servo-burst areas can be reduced. The reduced servo-burst areas can increase the total user area and thus increase the recording capacity of the recording medium, without degrading the accuracy of the positioning control of the reproducing heads, which are disposed in operative relationship with the servo-burst area according to the data recording/reproducing device of the present invention.
The above and other objects, features and advantages of the present invention will be more apparent from the following description, referring to the accompanying drawings.
REFERENCES:
patent: 4334252 (1982-06-01), Toriu
patent: 4669004 (1987-05-01), Moon et al.
patent: 5943180 (1999-08-01), Seo et al.
Ikeda Hiroyuki
Seo Yuzo
Hindi Nabil
Mitsubishi Chemical Corporation
Neal Regina Y.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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