Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2001-08-16
2003-12-09
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S235800, C360S235700
Reexamination Certificate
active
06661611
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an air bearing slider for carrying a transducing head in a disc drive. More particularly it relates to an air bearing slider capable of operating at ultra-low flying heights.
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 s speeds, which generates a wind of air immediately adjacent to the flat surface of the disc. This wind acts upon a 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 height above the disc. 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. A slider is typically mounted on a gimbal and load beam assembly which biases the slider toward the rotating disc, providing a pre-load force opposite to the lift force acting on the air bearing surface of the slider. For the slider to maintain the ultra-low flying height above the surface of the disc the lift force must be balanced with the pre-load and suction forces.
As disc storage systems are designed for greater and greater storage capacities, the density of concentric data tracks on discs is increasing (that is, the size of data tracks and radial spacing between data tracks is decreasing), requiring that the air bearing gap between the transducing head carried by the slider and the rotating disc be reduced. One aspect of achieving higher data storage densities in discs is operating the air bearing slider at ultra-low flying heights. Shrinking the air bearing gap and operating the slider at ultra-low flying heights has become a source of intermittent contact between the transducing head and the disc. Furthermore, when a disc drive is subjected to a mechanical shock of sufficient amplitude, the slider may overcome the biasing pre-load force of the load beam assembly and further lift away from or off the disc. Damage to the disc may occur when the slider returns to the disc and impacts the disc under the biasing force of the load beam. Such contact can result in catastrophic head-disc interface failure. Damage to the disc may include lost or corrupted data or, in a fatal disc crash, render the disc drive inoperable. Contact resulting in catastrophic failure is more likely to occur in ultra-low flying height systems. In addition, intermittent contact induces vibrations detrimental to the reading and writing capabilities of the transducing head.
For the disc drive to function properly, the slider must maintain the proper fly height and provide adequate contact stiffness to assure that the slider does not contact the disc during operation. Also, the air bearing slider must have enhanced take-off performance at start up to limit contact between the slider and the disc. Such contact would cause damage to the slider during take-off and landing of the slider.
Air bearing sliders typically possess three primary degrees of movement, which are vertical motion, pitch, and roll rotation. The movement is relative to the gimbal and load beam associated with three applied forces upon the slider defined as pre-load, suction, and lift force. Steady state fly attitude for the slider is achieved when the three applied forces balance each other. Variations in disc drive manufacturing, such as pitch static angle or pre-load variation, result in varying fly attitude and intermittent contact with the disc. However, increasing pitch and vertical stiffness of the air bearing slider results in a greater resistence to varying fly heights. Increasing stiffness of the slider is achieved by generating more suction and lift force per unit area on the air bearing surface of the slider.
Air bearing slider designs are known in the art that increase the suction force. However there is a need in the art for a slider capable of generating greater localized lift force. Larger suction and lift forces yield greater contact stiffness, enhance take-off performance and improve dampening capability. In general, increasing the suction and lift forces lowers manufacturing sensitivity and minimizes intermittent contact between the slider and the disc.
BRIEF SUMMARY OF THE INVENTION
The present invention is a slider for supporting a transducing head proximate a rotating disc. The slider has a slider body having a disc opposing face and a longitudinal axis. The disc opposing face is bounded by a leading edge, a trailing edge, and first and second side edges. An air bearing surface is defined on the disc opposing face, with the air bearing surface having at least one pad behind the leading edge. A cavity is positioned on the disc opposing face and the cavity is recessed from the air bearing surface at a cavity depth. At least a portion of the cavity precedes the pad. A funnel directs air flow within the cavity from the leading edge toward the pad.
Another embodiment of the present invention has at least one trench positioned adjacent to the pad. The trench is recessed from the air bearing surface at a step depth.
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Bogy et al., “Reliability Criteria for Dynamic Load/Unload”, Computer Mechanics Laboratory Research Report, Dept. of Mechanical Engineering, University of California Berkeley, 1999.
Yong Hu et al., “Partial Contact Air Bearing Characteristics of Tripad Sliders for Proximity Recording”, Transaction of the ASME, vol. 120, 1998.
Chapin Mark A.
Mundt Michael D.
Rao Ram M.
Ryun Scott E.
Sannino Anthony P.
Kinney & Lange , P.A.
Seagate Technology LLC
Tupper Robert S.
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