Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2001-10-18
2003-07-15
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S236300, C360S235700
Reexamination Certificate
active
06594113
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an air bearing slider carrying a transducing head in a disc drive. More particularly, it relates to capturing contaminants on the slider and expunging the contaminants from the slider.
Air bearing sliders have been extensively used in disc drives to appropriately position a transducing head above a rotating disc. In most high capacity storage applications, when the disc is at rest, the air bearing slider is in contact with the disc. During operation, the disc rotates at high speeds, which generates a wind of air immediately adjacent the flat surface of the disc. The wind acts upon the lower air bearing surface of the slider and generates a lift force directing the slider away from the disc and against a load beam causing the slider to fly at an ultra-low fly height above the disc. A slider is typically mounted on a gimbal and load beam assembly which biases the slider toward the rotating disc, providing a preload force opposite to the lift force acting on the air bearing surface of the slider. In negative pressure sliders, the wind also acts upon a portion of the air bearing surface of the slider to generate a suction force. The suction force counteracts the lift force by pulling the slider back toward the surface of the disc. For the slider to maintain the ultra-low flying height above the surface of the disc, the lift force must be balanced with (and greater than) the preload and suction forces.
As disc storage systems are designed for greater and greater storage capacities, the density of concentric data tracks on the disc increases (that is, the size of data tracks and radial spacing between data tracks decreases). One aspect of achieving higher data storage densities in the disc is operating the air bearing slider at ultra-low flying heights. Furthermore, the increase in data storage densities requires that the air bearing gap, or head media spacing (HMS) between the transducing head carried by the slider and the rotating disc be reduced.
As the HMS has decreased, increased accumulation of contaminants, such as lubricant (lube), and debris on the slider has occurred. Lubricant is typically applied to the disc to prevent corrosion. Lube displaced by evaporation or head disc contact collects on the slider body. The collected lube typically migrates across the surface of the slider and accumulates in a location where airflow across the slider tends to produce a stagnation point. Lube accumulation on the slider results in flyability and stiction problems. Lube accumulation on the slider induces loss of fly height resulting in intermittent contact between the slider and the disc until finally a crash occurs between the two. Additionally, lube accumulated on the slider and lube on the disc create a friction between the slider and the disc, and the lube acts as an adhesive between the two. When the disc begins spinning, the motor does not have enough torque to overcome the stiction force between the disc and the slider, thereby resulting in poor takeoff performance or the inability of the slider to takeoff from the disc.
Particle contamination on the slider results in loss of data or a skip write (or head bounce). Fly height of the slider is typically less than 0.5 microns, however particle size can be greater than 0.5 microns. During particle contamination, particles accumulate on the slider and either embed in the disc surface or create a bump on the disc surface. A particle embedded in the disc surface causes data to be lost or results in a skip write. A particle forming a bump on the disc results in a head bounce or the particle will become further embedded in the disc. During a head bounce, the slider contacts the bump, bounces upward and stops modulating, thereby preventing the slider from reading or writing to or from the disc.
In the past attempts at contaminant mitigation have been restricted to a center pad adjacent a trailing edge of the slider. Furthermore, typically these attempts displace the subambient pressure regions on the slider and increase sensitivity to manufacturing variations. Some other means include using a second head to clean the disc. However, a second head adds manufacturing costs to the disc drive. There is a need in the art for a slider with features that capture contaminants and expel them from the slider without displacing subambient pressure regions, with the ability to capture and flush contaminants from many regions of the slider and not increase the cost of manufacturing.
BRIEF SUMMARY OF THE INVENTION
The present invention relates to a slider for supporting a transducing head proximate a rotating disc. The slider includes a slider body having a disc opposing face bounded by a leading edge, a trailing edge and first and second side edges. The slider body has a longitudinal axis. An air bearing surface is defined on the disc opposing face. A furrow is positioned on the disc opposing face for flushing contaminants towards the trailing edge of the slider body.
In one preferred embodiment of the invention, a first side arm and a second side arm are recessed from the disc opposing face and extend from the furrow. The side arms flush contaminants into the furrow and thereby towards the trailing edge of the slider body.
In another preferred embodiment of the invention, first and second side rails are positioned substantially along the first and second side edges of the slider body. A first side furrow is disposed in the first side rail and a second side furrow is disposed in the second side rail. The side furrows flush contaminants from the disc opposing face of the slider body.
REFERENCES:
patent: 4212044 (1980-07-01), Plotto
patent: 4486798 (1984-12-01), Feliss et al.
patent: 4510541 (1985-04-01), Sasamoto
patent: 5467238 (1995-11-01), Lee et al.
patent: 5751517 (1998-05-01), Agarwal
patent: 5831792 (1998-11-01), Ananth
patent: 6233118 (2001-05-01), Boutaghou et al.
patent: 6424493 (2002-07-01), Matsumoto et al.
patent: 6449126 (2002-09-01), Dorius et al.
Rao Ram M.
Ryun Scott E.
Sannino Anthony P.
Schnur Deborah S.
Kinney & Lange , P.A.
Seagate Technology LLC
Tupper Robert S.
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