Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
1998-10-19
2001-05-08
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
Reexamination Certificate
active
06229672
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to air bearing sliders for use in rotary disk drives and in particular to the air bearing surface geometry of a slider.
BACKGROUND OF THE INVENTION
Magnetic heads used in disk drives typically incorporate air bearing sliders carrying magnetic transducers that fly over the surface of a magnetic disk for reading and writing data on the disk. The slider is supported by a gimbal connected to a load beam of a head arm suspension assembly. In response to signals from a control unit or computer, the suspension assembly positions the slider over selected tracks of the disk. As the disk rotates it generates an air flow parallel to the tangential velocity of the disk. The air flow provides a lift that allows the slider to fly above the disk. A close spacing or flying height between the transducer and the disk improves the transducing relationship between the magnetic transducer and the magnetic disk. When used with very narrow transducing gaps and very thin magnetic record films, the close spacing allows short wavelength, high frequency signals to be recorded, thereby affording high density, high storage capacity recording.
A major thrust in disk drive design is toward smaller compact drives with smaller components. As a result, head suspensions and head sliders are being reduced in size. The next generation of magnetic disk drives have pico-size sliders, and a planar head air bearing design where usable slider surface area is reduced substantially. A pico-size slider is about 0.049 inches long, about 0.039 inch wide and about 0.012 inch high. A pico-size slider is about 30% of the size of a standard slider. A micro-slider is about 70% of the size of a standard slider and a nano-slider is about 50% of the size of a standard slider.
Hard drives require minimal change in slider flying height over a range of velocity and skew conditions. This requirement is more difficult to satisfy as the load on the air bearing increases, or as the surface area for the air bearing decreases. In high load applications, e.g. where non-operating shock issues are of concern, maintaining a proper flying-height profile for gram loads that are typical of larger nano-size sliders is desirable.
Current designs for pico-size sliders support loads in the 2.0 to 2.5 gram range, and are able to maintain near constant flying heights from the inside diameter to the outside diameter of a disk in a hard drive. However, when the gram load is pushed up to 3.5 grams, the modeled profile delta (pd) increases to 0.2 or 0.3 micro-inches. Profile deltas above 0.1 micro-inches are considered unacceptable. A “profile delta” is the maximum flying height minus the minimum flying height as the slider tracks from the inside radius of the disk to the outside radius of the disk.
An object of the invention is to provide an air bearing design for a reduced size form factor slider that makes the flight attitude of the slider less sensitive to changes in velocity and skew angle.
Another object of this invention is to provide an air bearing surface for a pico-sized slider which flies at near constant height under conditions of changing velocity and skew angle, at relatively high gram loads.
Another object of this invention is to provide an air bearing slider having constant flying height at different radii of a magnetic storage disk.
SUMMARY OF THE INVENTION
According to this invention, an air bearing slider is formed with an air bearing surface (ABS) having three pads or rails encompassed by multiple recess areas. The three pads include a center pad and two side pads. The slider is defined by a leading edge and a trailing edge and has a central longitudinal axis. A first recessed or etched area is configured in a T-shaped form that encompasses the center pad. The leg of the central T-shaped recess extends toward the slider trailing edge. The central T-shaped recess is disposed asymmetrically about the slider central longitudinal axis. A second major recess is formed adjacent to the leg of the central recess of a different depth than the depth of the central T-shaped recess. The second recess area includes the perimeter portions along the leading edge and the side boundaries of the slider. In one implementation, recess areas of a different depth than the major recess are formed on both sides of each of the side pads.
The depth of the T-shaped central recess is relatively shallow, about 5-30 microinches, while the depth of major recess is greater, between 60-150 microinches, by way of example. It should be understood that more than two recesses can be implemented with the novel air bearing design disclosed herein.
The invention has the advantage that by using two recessed areas of different depths and incorporating arbitrary shaping of the three ABS pads, a substantially constant flying height, with variations ≦0.1 microinch over the data zone, can be achieved while supporting a 3.5 gram load in a picoslider form factor. The novel design helps hard disk drive products circumvent the shock/vibration problems generally encountered on picoslider suspensions with a standard 2.5 gram load. The novel air bearing design incorporates a second recess depth to achieve subambient pressure thereby increasing the overall air bearing stiffness of the slider.
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Anaya-Dufresne Manuel
Chang Ciuter
Lee Christopher A.
Levi Pablo G.
Prabhu Pravin P.
Altman, III Franklin D.
Evans Jefferson
Kallman Nathan N
Read-Rite Corporation
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