Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2000-08-28
2002-10-08
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S235600, C360S235700, C360S236000, C360S236100
Reexamination Certificate
active
06462909
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to disc drive data storage systems and, more particularly, to a disc drive data storage system having a slider, which dampens various modes of excitation of slider vibration.
Disc drives of the “Winchester” and optical types are well known in the industry. Such drives use rigid discs, which are coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor, which causes the discs to spin and the surfaces of the discs to pass under respective hydrodynamic (e.g. air) bearing disc head sliders. The sliders carry transducers, which write information to and read information from the disc surfaces.
An actuator mechanism moves the sliders from track-to-track across the surfaces of the discs under control of electronic circuitry. The actuator mechanism includes a track accessing arm and a suspension for each head gimbal assembly. The suspension includes a load beam and a gimbal. The load beam provides a load force which forces the slider toward the disc surface. The gimbal is positioned between the slider and the load beam, or is integrated in the load beam, to provide a resilient connection that allows the slider to pitch and roll while following the topography of the disc.
The slider includes a bearing surface, which faces the disc surface. As the disc rotates, the disc drags air under the slider and along the bearing surface in a direction approximately parallel to the tangential velocity of the disc. As the air passes beneath the bearing surface, air compression along the air flow path causes the air pressure between the disc and the bearing surface to increase, which creates a hydrodynamic lifting force that counteracts the load force and causes the slider to lift and fly above or in close proximity to the disc surface.
The bearing clearance between the slider and the disc surface at the recording head is an important parameter to disc drive performance. Slider bearings in computer hard drives have three degrees of freedom, including vertical motion, pitch rotation and roll rotation. The three degrees of freedom are associated with three vibration modes. As in any mechanical system, these three vibration modes have respective natural, or “resonant”, frequencies, which depend on the mass and stiffness of the respective degree of freedom. When a slider is subjected to an external vibration source having a frequency that resides in the vicinity of one or more of the bearing's natural frequencies, the slider sustains vibrations, which often result in significant modulation of the head-media spacing. Modulation of the head-media spacing degrades the head's read and write performance and can cause intermittent contact between the head and the disc surface.
As bearing clearances continue to decrease to achieve greater recording densities, micro-waviness in the disc surface has been observed to be an increasing source of vibration excitation for sliders, especially at flying heights below 0.5 microinches. Since micro-waviness is a broadband frequency type of excitation, it is often impossible to de-couple the bearing's natural frequency with the frequency of the excitation source by changes to the geometry of the bearing surface.
A slider is desired, which dampens head-media separation modulation in response to dynamic excitation induced by media micro-waviness at flying heights below 0.5 microinches.
SUMMARY OF THE INVENTION
One aspect of the present invention relates to disc head slider for supporting a transducer relative to a data storage disc. The slider includes a slider body having a disc-facing surface with a leading slider edge and a trailing slider edge. First and second rails are disposed on the disc-facing surface about a central recess and form first and second bearing surfaces, respectively, which terminate prior to the trailing slider edge. First and second wear-resistant pads are formed on the disc-facing surface between respective ones of the first and second bearing surfaces and the trailing slider edge. The first and second wear-resistant pads are raised from the central recess and are recessed from the first and second bearing surfaces to provide transitions in the disc-facing surface that generate vibration-dampening pressure gradients while limiting contact between the pads and the data storage disc during operation.
Another aspect of the present invention relates to a disc head slider, which includes a slider body having a disc-facing surface with a leading slider edge and a trailing slider edge. A bearing and a wear-resistant pad are formed on the disc-facing surface. The wear-resistant pad includes a convergent channel, which has a leading channel end open to fluid flow from the leading slider edge toward the trailing slider edge, non-divergent channel side walls, and a trailing channel end closed to the fluid flow.
Another aspect of the present invention relates to a disc drive assembly, which includes a disc and a slider bearing. The disc is rotatable about a central axis and has a recording surface with a circumferential waviness characteristic. The slider bearing has a wear-resistant pad for reducing wear on the slider bearing and the disc during rotation of the disc and for generating vibration dampening pressure gradients between the bearing surface and the disc.
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Boutaghou Zine-Eddine
Hanchi Jorge V.
Sannino Anthony P.
Seagate Technology LLC
Tupper Robert S.
Westman Champlin & Kelly
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