Disk drive spindle air bearing with features to improve start-stop performance

DETAILED DESCRIPTION The present invention relates to an air bearing structure for use in a disk drive device that produces relatively little stiction between air bearing surfaces during an initial disk spin up period.
In general, the structures of the present invention are designed to minimize contact between the air bearing surfaces of the bearing when the hub of the disk drive is at rest or rotating below a threshold velocity.
This minimization of contact is accomplished with relatively little effect on the performance of the air bearing.
The inventive structures also provide for a significant reduction in the collection of wear particles in the air bearing region.
The principles of the present invention can be used in virtually any form of disk drive device, including magnetic disk drives, optical drives, and other data storage devices utilizing a disk shaped medium.
In accordance with the present invention, reduced contact between thrust bearing surfaces is achieved by appropriately shaping the bearing surfaces.
Air bearings of the past typically parallel thrust bearing surfaces in the air bearing region to achieve the necessary lift.
Consequently, the gap height of these prior thrust bearings is constant as a function of radial distance from the axis of rotation.
In accordance with the present invention, the bearing surfaces of the thrust bearing are shaped such that the height of the gap between the bearing surfaces varies as a function of radial distance.
This non-uniform gap height exists while the disk is at rest and also when the disk is rotating at full operational speed (and at all speeds in between).
Therefore, contact between the air bearing surfaces during reduced velocity operation is limited to a small portion of the overall surface areas of the air bearing surfaces.
The reduced contact area also generates considerably less stiction on subsequent spin up of the disk than would a parallel plate configuration.
Various bearing surface shaping techniques are provided in accordance with the present invention