Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
1999-09-17
2003-08-12
Korzuch, William (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
Reexamination Certificate
active
06606222
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 with a convergent channel feature.
Disc drives of the “Winchester” type 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.
One type of slider is a “self-loading” air bearing slider, which includes a leading taper, a pair of raised side rails, a cavity dam and a subambient pressure cavity. The leading taper is typically lapped or etched onto the end of the slider that is opposite to the recording head. The leading taper pressurizes the air as the air is dragged under the slider by the disc surface. An additional effect of the leading taper is that the pressure distribution under the slider has a peak near the taper end or “leading edge” due to a high compression angle of the taper, and a second peak near the recording end or “trailing edge” due to a low bearing clearance for efficient magnetic recording. This dual-peak pressure distribution results in a bearing with a high pitch stiffness.
The bearing clearance between the slider and the disc surface at the recording head is an important parameter to disc drive performance. It is desired to minimize variation in the head clearance or “flying height”. As average flying heights continue to be reduced, it is important to control several metrics of flying height performance, such as flying height sensitivity to process variations, ambient pressure (e.g., altitude) variations, changes in radial position of the slider over the disc surface and resulting head skew, and quick movements of the slider from one radial position to another radial position. Also, the slider should take off from the disc surface as quickly as possible after the start of disc rotation.
The above-mentioned sensitivities are reduced by providing the slider with a high bearing stiffness in the pitch and roll directions. To achieve high pitch and roll stiffness, air bearings have utilized geometries that distribute the positive pressure away from the center of the slider. However, with some bearing geometries, it is difficult to generate sufficient localized pressure along certain areas of the bearing surface. For example, it is difficult to generate localized positive pressure near the trailing edge of a slider having truncated side rails and a discrete center pad positioned at the trailing edge.
More effective bearing features are desired for generating localized pressure along selected areas of a bearing surface.
SUMMARY OF THE INVENTION
One aspect of the present invention relates to a disc head slider including a slider body having a leading slider edge, a trailing slider edge and a slider length measured from the leading slider edge to the trailing slider edge. First and second raised rails are positioned on the slider body, which have first and second bearing surfaces, respectively. A recessed area is positioned between the first and second side rails and has a recess floor. A first raised pad is positioned rearward of a midpoint along the slider length and includes a third bearing surface, which is generally coplanar with the first and second bearing surfaces. A convergent channel is recessed within the third bearing surface and trails a portion of the recessed area. The convergent channel includes a leading channel end open to fluid flow from the portion of the recessed area, non-divergent channel side walls and a trailing channel end closed to the fluid flow and forward of a localized region of the third bearing surface.
Another aspect of the present invention relates to a disc drive assembly, which includes a housing, a disc rotatable about a central axis within the housing, an actuator mounted within the housing and a slider supported over the disc by the actuator. The slider includes a slider body having a leading slider edge, a trailing slider edge and a slider length measured from the leading slider edge to the trailing slider edge. First and second raised rails are positioned on the slider body, which comprise first and second bearing surfaces, respectively. A recessed area is positioned between the first and second side rails and has a recess floor. A first raised pad is positioned rearward of a midpoint along the slider length and includes a third bearing surface, which is generally coplanar with the first and second bearing surfaces. A convergent channel is recessed within the third bearing surface and trails a portion of the recessed area. The convergent channel includes a leading channel end open to fluid flow from the portion of the recessed area, non-divergent channel side walls and a trailing channel end closed to the fluid flow and forward of a localized region of the third bearing surface.
Yet another aspect of the present invention relates to a disc drive assembly, which includes a disc rotatable about a central axis and a slider supported over the disc for generating a fluid bearing between the slider and the disc as the disc rotates beneath the slider about the central axis.
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Castro Angel
Korzuch William
Seagate Technology LLC
Westman Champlin & Kelly
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