Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
1999-05-21
2002-10-15
Holder, Regina N. (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S067000, C360S077020
Reexamination Certificate
active
06466394
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a storage device used as an external storage device for a computer or the like as well as to a method of detecting a position of a head on a disk used for the same and more particularly, to a storage device for detecting a position of a magnetic head on a magnetic disk with a data region and a servo region provided thereon based on time division (“time division mode”) as well as to a method of detecting a position of head on a disk used for the same.
BACKGROUND OF THE INVENTION
In recent years storage devices having great storage capacity are widely used. As a method of detecting a position of a magnetic head on a magnetic disk in such a storage device there is know a method of previously recording the servo patterns on the magnetic disk and detecting a position of the magnetic head thereon according to the servo patterns.
As an external storage device for a computer or the like, a storage device having a magnetic disk as a storage medium are widely used. A magnetic disk has a data region for storing therein data and a servo region for previously recording therein servo patterns for servo controls existing thereon in time division mode.
This type of storage device is substantially configured with the magnetic disk, a magnetic head closely located with respect to the magnetic disk, a servo controlling section for servo controlling so that the magnetic head positions at a target position by moving the magnetic head along the direction of radius of the disk at the time of read seek and write seek, and a read/write circuit for controlling a write and/or read operation of the magnetic disk using the magnetic head.
Herein, the magnetic head has a write core for writing data in a data region on the magnetic disk with a magnetic field generated by a current for recording fed from the read/write circuit, and a read core for magnetically detecting the data written in the data region and detecting a servo pattern recorded on the servo region.
The servo controlling section detects a position of the magnetic head on the magnetic disk according to a phase of the servo pattern detected by the read core of the magnetic head and then moves the magnetic head on the magnetic disk to a target position. More specifically, the servo controlling section servo-controls the magnetic head while receiving feedback of information for a detected position obtained from the servo pattern so that a positional error between the detected position and the target position becomes zero.
Next description is made for specific configuration of the storage device based on the conventional technology and the operations performed during detection of a position of the head on the disk with reference to FIG.
5
A and FIG.
5
B through FIG.
9
. FIG.
5
A and
FIG. 5B
are perspective views each showing configuration of the key section of the storage device based on the conventional technology. In
FIG. 5A
, the magnetic disks
111
1
to
111
n
are n-pieces of disk-shaped recording medium for magnetically storing data therein, and are located at prespecified intervals in the axial direction in a multi-layered form. These magnetic disks
111
1
to
111
n
are rotated and driven with high speed by a spindle motor not shown in the figure. Further, each of the magnetic disks
111
1
to
111
n
has a data region for storing the data therein and a servo region for recording servo patterns therein respectively.
In each of the magnetic disks
111
1
to
111
n
, each region obtained by dividing a space between the most inner region and the most outer region thereof into concentric circles with a prespecified width therebetween (track pitch) is called a track TK. When the tracks TK on the magnetic disks
111
1
to
111
n
are extracted three-dimensionally, these tracks TK are arranged cylindrically. A set of plurality of tracks TK existing at the same distance in the radial direction from the center on the surfaces of each of the magnetic disks
111
1
to
111
n
are called cylinders C
1
to Cn (Refer to FIG.
5
B).
FIG. 6
is a view showing servo regions RS on each of the magnetic disks
111
1
to
111
n
. In the figure, the same reference numerals are assigned to the sections corresponding to those in FIG.
5
A and
FIG. 5B
, and description thereof is omitted herein. It should be noted that
FIG. 6
shows an example of servo regions RS each provided as a linear shape and also shows the cylinders C
0
to C
3
of the cylinders C
0
to Cn to facilitate the understanding thereof.
In
FIG. 6
, four cylinders C
0
to C
3
are set as one group. Those cylinders C
0
to C
3
(or the tracks TK) are located adjacent to each other with boundries K, K, . . . at a track pitch TP. Herein the track pitch is 2 &mgr;m. A total of three lines of servo patterns S
3
, S
3
, . . . with a phase difference of 90 degree from each other are recorded in time division mode on each of the cylinders C
0
to C
3
.
Namely, taking the cylinder C
0
as an example, three lines of servo patterns S
3
, S
3
, . . . are recorded on this cylinder C
1
at a prespecified interval therebetween so as to divide one track pitch TP into m (m=3 in the example of the figure) divisions. These patterns S
3
, S
3
, . . . are magnetic patterns used for positions of the magnetic heads
113
1
to
113
n
on the magnetic disks
111
1
to
111
n
. Herein a servo pattern length L
3
of the servo pattern S
3
is set to ⅓ of the track pitch TP.
Returning back to
FIG. 5A
, the magnetic heads
113
1
to
113
n
each have a read core and a write core having an extremely narrow gap, and are located adjacent to the magnetic disks
111
1
to
111
n
respectively. Each of the magnetic heads
113
1
to
113
n
has a write core W (Refer to
FIG. 7
) for writing data in each of the magnetic disks
111
1
to
111
n
with a magnetic field generated by a recording current fed when writing, and a read core R (Refer to
FIG. 7
) for magnetically detecting the data and the servo patterns S
3
(Refer to
FIG. 6
) recorded on each of the magnetic disks
111
1
1
to
111
1
. A number n of the magnetic heads
113
1
to
113
n
is decided according to a number n of the magnetic disks
111
1
to
111
n
.
Herein, on the magnetic head
1131
shown in
FIG. 7
, a center line Xb linking the read core R to the write core W and a tangent line Xa of the cylinder C
1
where the read core R positions make an angle &thgr; of yaw. A width WR of the read core R is around ½ of the track pitch TP because of designing restriction, and is more specifically 0.7 &mgr;m to 1.3 &mgr;m. Also, since there is the angle &thgr; of yaw as described above, an effective read-core width WR′ with respect to the cylinder C
1
becomes WR·cos&thgr;.
Operations for detecting a position of a head on a disk in the storage device based on the conventional technology will be described in the following. In
FIG. 5A
, when a spindle motor not shown herein is driven, the magnetic heads
113
1
to
113
n
are concurrently rotated and driven. Description centering on an operation of the magnetic head
113
1
will be made hereinafter to simplify the description.
Assuming herein that the magnetic head
113
1
shown in
FIG. 7
positions outside the cylinder C
0
and that the magnetic head
113
1
is moved from the current position to a central position of the cylinder C
1
shown in the same figure, the servo controlling section (not shown herein) moves the magnetic head
113
1
at a ⅓-track pitch in the radius direction of the disk.
With this operation, the magnetic head
113
1
is first moved so as to traverse the cylinder C
0
. During this movement, the servo patterns S
3
, S
3
, . . . are detected by the read core R, and the servo controlling section generates a positional error signal from the difference between a detected position signal according to a phase difference of each servo patterns S
3
and a target position signal according to a target position of the magnetic head
113
1
.
The servo controlling section amplifies the positional error signal with a
Kosugi Tatsuhiko
Saito Tomoaki
Greer Burns & Crain Ltd.
Holder Regina N.
Slavitt Mitchell
LandOfFree
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