Dynamic magnetic information storage or retrieval – Head mounting – For shifting head between tracks
Reexamination Certificate
2001-01-10
2004-05-18
Letscher, George J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head mounting
For shifting head between tracks
Reexamination Certificate
active
06738228
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to magnetic head positioner assembly for use in disk storage systems such as magnetic or optical disk storage systems.
2. Description of the Related Art
The density of storage of data in magnetic disk units are now increasing at an annual rate of 60% or more due to an improvement in BPI (Bit Per Inch) and TPI (Track Per Inch).
To realize a higher BPI, required are a reduction in height at which magnetic heads fly over the disk surface, the employment of highly sensitive heads, and highly efficient signal processing techniques. To realize a higher TPI, a technique for positioning magnetic heads with high accuracy is inevitable in addition to the foregoing.
For example, a density of storage of data of 0.155 Gb/cm
2
(1 Gb/in
2
) provides densities of 8 kTPI or less in the direction of tracks or track pitches of 3 to 4 &mgr;m. To realize a density of storage of data of 1.55 Gb/cm
2
(10 Gb/in
2
) or greater, track densities of 25 kTPI or greater or track pitches of 1 &mgr;m or less are required. This in turn requires an accuracy of positioning of magnetic heads on the disks of 0.1 &mgr;m or less (which is approximately equal to 10% of a track pitch).
FIG. 1
is a perspective view showing a conventional magnetic head positioner assembly. In addition,
FIG. 2
is an exploded perspective view showing the arrangement of the conventional magnetic head positioner assembly. Moreover,
FIGS. 3A and 3B
are plan and perspective views showing a magnetic head support member of the conventional magnetic head positioner assembly, respectively.
As shown in
FIG. 1
, the conventional magnetic head positioner assembly comprises magnetic head support members
510
, an arm
520
for holding the magnetic head support members
510
, and a movable coil
530
provided at the arm
520
.
As shown in
FIGS. 2
,
3
A, and
3
B, the magnetic head support member
510
comprises a slider
512
of a floating or a contact type to which a magnetic head
511
is mounted, a gimbal spring
513
for supporting the slider
512
, and a load beam
514
for providing a predetermined push load for the slider
512
. In addition, the magnetic head support member
510
is fitted into a magnetic head support member mounting hole
528
provided on a holder arm
525
of the arm
520
, via a boss
515
a
provided on a base plate
515
.
FIG. 4
is a plan view showing the main portion of a conventional disk storage system. As shown in
FIG. 4
, a plurality of holder arms
525
which support the magnetic head support members
510
are integrated with the arm
520
at the proximal end thereof and mounted rotatably into the magnetic disk storage system via a rotatable bearing portion
527
provided on the arm
520
.
At the end portion of the arm
520
, there is formed a movable coil support portion
529
and the movable coil
530
is provided on the movable coil support portion
529
. Moreover, the movable coil
530
and an external stationary magnetic circuit
560
on the side of the magnetic disk storage system constitute a voice coil motor (hereinafter referred to as the VCM). The VCM applies a predetermined drive current to the movable coil
530
and thereby generates a drive force to rotationally drive the arm
520
or the magnetic head support members
510
along a circular arc path in the direction of a seek operation (in the radial direction of the disks). This allows the positioning operation of the magnetic heads
511
to target tracks on the disks (the rotary actuator scheme).
Incidentally, the positioning operation mentioned above is divided into a seek operation (tracking) for moving the magnetic head
511
from the position of an arbitrary track to that of a target track and a follow operation (following) for allowing the magnetic head
511
to remain on the target track.
The magnetic heads
511
are prepared according to the number of recording media. In addition, each magnetic head support member
510
for individually supporting each magnetic head
511
is also swaged to each of the holder arms
525
according to the number of the magnetic heads
511
. For example, two recording media provide four data recording surfaces on the both surfaces of the media. In this case, a total of four magnetic head support members
510
is swaged to the holder arms
525
, respectively.
FIG. 5
is a side view showing the entire conventional magnetic head positioner assembly.
FIG. 6
is an enlarged side view showing the region shown by P
3
of FIG.
3
. In the case where two recording media are available, the arm
520
comprises three holder arms
525
as shown in
FIGS. 5 and 6
. One magnetic head support member
510
is mounted to each of the holder arms
525
a
,
525
a
at the both ends of the stack of the holder arms
525
. On the other hand, two magnetic head support members
510
are mounted to the middle holder arm
525
b
sandwiched by the two recording media
40
with each of the arm
520
being arranged to be opposite to each of the associated data recording surfaces of the recording media.
In addition, the conventional magnetic head positioner assembly is adapted to drive a plurality of magnetic heads
511
with one VCM at the same time. This provides insufficient positioning accuracy and particularly inaccurate tracking during a follow operation. Thus, as described above, this is making it difficult for the conventional magnetic head positioner assembly to cope with a high TPI system which requires a magnetic head positioning accuracy of 0.1 &mgr;m or less.
Moreover, consider the case where a plurality of recording media are incorporated into a disk storage system to provide an increased capacity therefor. In this case, one magnetic head support member
510
is connected to each of the holder arms
525
a
,
525
a
at the both ends of the stack of the holder arms
525
. In contrast, the middle holder arm
525
b
sandwiched by the recording media is connected with two magnetic head support members
510
,
510
. This will cause a difference in mass between the holder arms
525
a
and
525
b
, thereby presenting a problem of providing different vibration characteristics between the magnetic heads
511
a
,
511
d
at the both ends of the stack and the magnetic heads
511
b
,
511
c
at the middle portion of the stack.
This is conceivably resulted from a difference in mass caused by a difference in number of HGA (Head Gimbal Assembly) connected to the holder arms
525
a
,
525
a
located at the both ends of the stack and the middle holder arm
525
b
located at the middle portion of the stack. To improve this, it is commonly implemented to provide a dummy mass equivalent to the mass of the HGA for the holder arms
525
a
,
525
a
located at the both ends of the stack, thereby providing the same frequency characteristics for each of the magnetic heads. However, this allows the drive portion (the edge portion of the arms) to be provided with an additional excessive mass (dummy mass), thus presenting a problem of narrowing a control band due to the lowering of a resonance frequency to a lower band.
In addition, in a system with a plurality of recording media being implemented therein, the number of holder arms would increase as the number of recording media increases, thereby making the shape of the arm integrated therewith more complicated. This makes it difficult to form the arm. Furthermore, for example, forming the arm by cutting would present a problem of producing a great amount of cuttings and reducing in yield.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a disk storage system having a plurality of recording media implemented therein with a magnetic head positioner assembly which is provided with good vibration characteristics by eliminating a difference in frequency characteristics among the magnetic heads and which provides good productivity.
A magnetic head positioner assembly according to a first aspect of the present invention comprises a plurality of magnetic head support members for individually supp
Beacham Christopher R
Letscher George J.
TDK Corporation
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