Slider and head assembly

Details Slider and head assembly Slider and head assembly

1998-09-17

2004-05-04

Tupper, Robert S. (Department: 2652)

Dynamic magnetic information storage or retrieval

Fluid bearing head support

Disk record

C360S294300, C360S294500

Reexamination Certificate

active

06731462

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a slider or head assembly used in such fields as magnetic storage.
2. Description of the Related Art
A hard disk drive (hereinafter referred to as HDD) is a well known magnetic storage. An HDD utilizes a disk as a storage medium. The following is description of the case where a disk is used as a storage medium.
In the field of HDD, storage capacity is rapidly increasing. Storage media (hereinafter referred to as disks) and magnetic heads are being developed to cope with this high storage capacity. The magnetoresistive head (hereinafter referred to as MR head) is well known as a magnetic head that copes with high storage capacity.
An MR head that copes with high storage capacity is being manufactured with a track width on the order of several microns. Further, storage capacity is increasing at a rate approaching 5 Gb/in
2
. A tracking operation in an HDD involves moving an MR head-equipped slider in a track on a disk and reading magnetic signals recorded on that track. In this tracking operation, a method is used whereby the slider is held by a suspension, and this suspension is driven by a voice coil motor.
The assembly that joins a suspension to a slider that positions an MR head is called a head assembly. A conventional example of this head assembly is described.
An HDD is provided with a voice coil motor (hereinafter referred to as VCM) near the base of the suspension. The VCM drives the suspension, and controls the position of the slider mounted at the tip of the suspension. The magnetic head is positioned above a track on a disk by controlling the position of the slider.
A track of several &mgr;m or less in width is provided on a disk, and the tracks are in close proximity to one another.
A slider has a flying surface that faces the disk. When the disk rotates, an airflow is produced between the slider flying surface and the disk, generating a force that causes the slider to float above the disk. In this manner, the MR head provided on the slider magnetically records information on the disk, and/or reads magnetically recorded information from the disk.
An increase in storage capacity affects recording and reading accuracy. Disk track width becomes narrower in line with increased storage capacity. As a result of this, finer tracking operations are required. Therefore, in this tracking operation, the MR head must be accurately moved to a micro-track region.
A tracking operation, as described above, means moving an MR head built into a head assembly to a track region by driving the head assembly suspension by using a VCM. However, because the accuracy of VCM-driven movement is limited, it is impossible to achieve high positioning accuracy.
With a low-positioning-accuracy tracking operation, the MR head is affected by an adjacent track, resulting in a heightened noise level. A rise in the noise level causes a drop in read-write accuracy.
Further, because the drive of the VCM is transmitted to the MR head via the suspension, it is not possible to drive the MR head with a high speed of response. When the head assembly drive speed is slow, it is impossible to speed up the overall write operations and read operations of an HDD, even though the signal frequency of the electronic circuit, which processes the write signals and read signals, is increased.
Conventional technology, which attempts to solve for the above-mentioned problems, is described below.
FIG. 14
is an oblique view showing a schematic of a head assembly disclosed in “INVAR MEMS MILLIACTUATOR FOR HARD DISK DRIVE APPLICATION” on pages 378-382 of IEEE Catalog Number 97CH36021, and “ANGULAR MICROPOSITIONER FOR DISK DRIVES” on pages 454-459 of the same catalog.
FIG. 14
shows a head assembly comprising a slider
901
having a flying surface
911
, an actuator
902
, a suspension
903
, and an MR head
12
.
The actuator
902
has a movable portion
922
on a substrate, as shown in
FIG. 15
, which is a cross-sectional view of the C-C′ portion of FIG.
14
. The actuator
902
, rotating or linearly moving the movable portion
922
, performs tracking by rotating or linearly moving the slider
901
.
That is, with this technology, in addition to using a VCM to move (with rough movement) the MR head via a suspension, an attempt is made to enhance drive accuracy by mounting an actuator
902
to the slider
901
and utilizing this actuator
902
to refine the movement of the MR head.
Furthermore, when describing this technology, the drive portion
921
of the actuator
902
is affixed to the slider
901
side, while the movable portion
922
is affixed to the suspension
903
side. The rotating movement or linear movement of the movable portion
922
causes the slider
901
to rotate or to move linearly. The movement of the slider
901
implements the tracking of the MR head
12
with good accuracy at the prescribed position.
The problems that arise with the technology illustrated in
FIGS. 14 and 15
when attempts are made to further increase storage capacity are described here.
As, in this prior art, mounted on top of the slider
901
is an actuator
902
, which has a drive portion
921
and a movable portion
922
to move the MR head
12
, the overall thickness and weight of the head assembly (in this prior art, this assembly comprises a slider
901
with an MR head, a suspension
903
and an actuator
902
) increases by the amount of the actuator
902
, and the center gravity is heightened.
The reading of a signal recorded on a disk is performed via the following operation. A slider of floating type is moved at high speed above the track to be read on a rotating disk. Hereinafter, the movement of this slider is called a seek operation. A sensor portion provided on the slider reads the magnetic storage recorded on a track. The slider is controlled so that the flying height, which is the distance between the built-in sensor portion and the disk, is constant.
A high center gravity position of a slider causes the slider to sink. A large slider sink results in larger angle of inclination of the slider flying surface which faces the surface of the disk. A large slider sink makes it impossible to control the flying height in a consistent manner. The problem is that a change in the flying height of a slider at seek causes the slider to make contact with the disk, damaging the disk. There is also the problem that a change in the flying height of a slider during reading generates noise.
Further, there is the problem that an increase in the weight of a slider increases the inertial force applied to the tip of the head assembly at seek, making tracking difficult.
A disk array HDD is formed by stacking a plurality of disks, a plurality of heads and a plurality of suspensions. In a disk array HDD, the distance between a slider's flying surface and a suspension is the sum of the respective thicknesses of the slider, head and suspension. An increase in the thickness of each component increases the spacing between the disks, increasing the thickness of the HDD. An increase in the thickness of the HDD makes it difficult to incorporate the HDD into equipment such as portable personal computers, which are required to make the overall thickness thinner.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the present invention is to design a head assembly of the type that has an actuator built into the slider so as to curb the weight and thickness thereof.
The present invention makes the thickness of the slider partially thinner, forming a thin plane portion. The plane portion is formed by a step portion or a flat portion on the slider. The head assembly is configured by joining an actuator to the thin plane portion. This configuration makes the thickness of the assembly that joins together the slider and the actuator substantially thinner. The present invention prevents increases in the thickness and weight of the tip of the head assembly, and stabilizes flying characteristics.
The plane portion is formed on the surface of the side opposite the flyin

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