Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2002-06-24
2003-12-16
Renner, Craig A. (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S254800
Reexamination Certificate
active
06665146
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to magnetic disk data storage systems, and more particularly to the use of a ramp to facilitate the loading and unloading of sliders.
Magnetic disk drives are used to store and retrieve data for digital electronic apparatuses such as computers. In
FIGS. 1A and 1B
, a magnetic disk data storage system
10
of the prior art includes a sealed enclosure or housing
12
, a spindle motor
14
, a magnetic medium or disk
16
, supported for rotation by a drive spindle S
1
of the spindle motor
14
, a voice-coil actuator
18
and a load beam
20
attached to an actuator spindle S
2
of voice-coil actuator
18
. A slider support system consists of a flexure
22
coupled at one end to the load beam
20
, and at its other end to a slider
24
. The slider
24
, also commonly referred to as a head or a read/write head, typically includes an inductive write element with a sensor read element.
As the motor
14
rotates the magnetic disk
16
, as indicated by the arrow R, an air bearing is formed under the slider
24
allowing it to “fly” above the magnetic disk
16
. Discrete units of magnetic data, known as “bits,” are typically arranged sequentially in multiple concentric rings, or “tracks,” on the surface of the magnetic disk
16
. Data can be written to and/or read from essentially any portion of the magnetic disk
16
as the voice-coil actuator
18
causes the slider
24
to pivot in a short arc, as indicated by the arrows P, over the surface of the spinning magnetic disk
16
. The design and manufacture of magnetic disk data storage systems is well known to those skilled in the art.
Reducing the distance between the slider
24
and the spinning disk
16
, commonly known as the “fly height,” is desirable in magnetic disk drive systems
10
as bringing the magnetic medium closer to the inductive write element and sensor read element improves signal strength and allows for increased areal densities. However, as the fly height is pushed to lower values, the effects of contamination at the head-disk interface become more pronounced. Specifically, debris may be collected over time on the air bearing surface of the slider
24
and which may ultimately cause the slider
24
to crash into the magnetic disk
16
causing the disk drive system
10
to fail. Consequently, reducing contamination within the sealed enclosure
12
is a continuing priority within the disk drive industry.
One strategy that has been used to reduce the debris that collects on slider
24
is to focus on the tribology at the head-disk interface to reduce the amount of contact between the slider
24
and the disk
16
when the system
10
is started and stopped. Traditionally, when a system
10
was shut down the slider
24
was parked on a track at the inner diameter (ID) of the disk
16
commonly known as a landing zone. There the slider
24
would rest in contact with the surface of the disk
16
until the disk was spun again, at which point the air bearing would form and the slider
24
would lift back off of the surface. Unfortunately, the friction and wear that occurred in these systems at the head-disk interface, even with improved lubricants, created unacceptable amounts of debris on the slider
24
to allow for still lower fly heights. In order to reduce friction and wear at the head-disk interface so as to reduce debris accumulation, the landing zone was improved by making it textured, often with a pattern of bumps, in order to reduce the contact area between the slider
24
and the disk
16
, among other reasons.
Textured landing zones proved effective to a point; however, the need to fly the slider
24
still lower, with the inevitable need to reduce contamination further, led to the development of techniques whereby the slider
24
is held off of the surface of the disk
16
when not in use. Such techniques seek to avoid any contact between the slider
24
and disk
16
at all. However, simply lifting the slider
24
higher off of the surface of the disk
16
is not sufficient because a system
10
in a portable computer system is subject to shock that can cause the slider
24
to slap into the disk
16
. Therefore, a technique used in the prior art to securely park the slider
24
away from the surface of the disk
16
, as shown in
FIG. 2
, is to employ a small ramp
30
placed proximate to the outer diameter (OD) of the disk
16
and tab
32
attached to the slider
24
. As the voice-coil actuator
18
causes the slider
24
to move toward the extreme OD the tab
32
rides up on the ramp
30
and lifts the slider
24
away from the surface. The slider
24
is pushed still further along the ramp
30
past the OD of the disk
16
to be parked on a flat or slightly indented portion on the ramp
30
.
FIGS. 3 and 4
serve to better illustrate the relationships between the components of ramp systems of the prior art.
FIG. 3
shows an elevational view, taken along the line
3
—
3
in
FIG. 2
, of a slider
24
of the prior art suspended beneath a load beam
20
by a flexure
22
. Attached to the end of the load beam
20
is a tab
32
intended to move in sliding contact with a ramp
30
for loading and unloading the slider
24
. Although shown as attached to the end of the load beam
20
, it should be noted that the tab
32
is typically formed as an integral part of the load beam
20
.
FIG. 4
shows an elevational view, taken along the line
4
—
4
of
FIG. 2
, of the ramp
30
relative to the tab
32
, read slider
24
, and the disk
16
, when the slider
24
is flying and the tab
32
is disengaged from the ramp
30
. For clarity, the load beam
20
and the flexure
22
are not shown. The tab
32
has a rounded bottom surface to reduce the contact area with the ramp
30
when the two are in sliding contact. Arrows in
FIG. 4
indicate the directions of motion of the load beam
20
for both loading and unloading.
One problem with a ramp
30
of this design is that the tab
32
is in sliding contact with the ramp
30
each time the system
10
is started or stopped. The sliding contact produces wear contamination that can be transferred to the disk
16
to be picked up by the air bearing surface of the slider
24
. The wear may be reduced by shaping the tab
32
so that the surface that contacts the ramp
30
is convex and by employing a lubricant. Although the amount of wear debris formed in this way is less significant compared to that which is generated with textured landing zones, nevertheless it may interfere with the aerodynamics of the slider
24
at very low fly heights and lead to crashes.
Another problem encountered with ramps
30
is that the slider
24
is not entirely parallel to the surface of the disk
16
. Rather, the leading edge of the slider
24
, the one facing into the direction of the rotation of the disk
16
, is higher than the trailing edge of the slider
24
to provide lift. Viewed another way, the pitch on the slider
24
causes the trailing edge to be closer to the surface. Similarly, since the air flow under the side of the slider
24
nearest the OD is always greater than under the side nearest the ID, the slider
24
may have some roll such that the ID edge of the slider is lower than the OD edge. Consequently, the corner of the slider
24
on the ID side of the trailing edge is commonly closest to the surface. As a slider
24
is loaded over a disk
16
the tab
32
slides down the ramp
30
until the lift experienced by the slider
24
is sufficient to cause the slider to fly.
What is desired, therefore, is a way to park the slider
24
on a ramp
30
while minimizing as much as possible the wear between the tab
32
and the ramp
30
. It is further desired to provide a smoother transition during loading and unloading.
SUMMARY OF THE INVENTION
The present invention provides for a ramp to assist the loading and unloading of a slider in a magnetic disk drive. The ramp comprises a body having a first surface and a second surface and a plurality of apertures extending between them, where each aperture has a first opening at
Bozorgi Jamshid
Hawwa Muhammad A.
Menon Aric
Renner Craig A.
Western Digital (Fremont)
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