Lubricant control in disc drive

Details Lubricant control in disc drive Lubricant control in disc drive

1998-11-30

2002-03-12

Hudspeth, David (Department: 2651)

Dynamic magnetic information storage or retrieval

Automatic control of a recorder mechanism

Synchronizing moving-head moving-record recorders

C360S075000

Reexamination Certificate

active

06356405

ABSTRACT:

BACKGROUND OF THE INVENTION
Magnetic disc drives for the storage of digital information in computerized systems are known. In such disc drives, a read/write head flies above the surface of spinning disc having magnetic media at its surface. The head is positionable to read and write information on concentric tracks on the disc. Typically the disc and head will have multiple layers to provide a compact arrangement, and the disc drives are sealed and have lubricant distributed over the media surfaces over which the head flies.
As the disc drive is exercised in ordinary use, the lubricant accumulates undesirably on head surfaces over time. The lubricant can migrate from air bearing stagnation regions between the head and the disc to air bearing surface regions of the head by capillary action. The process of migration is complex and depends on many factors such as lubricant viscosity and surface tension, the peak roughness of the disc surface, the length of the slider, temperature, as well as the presence of humidity and other contaminants.
When the disc drive is not in use for some time, the heads are landed in a landing zone and the spinning of the disc is stopped. When there is a large enough accumulation of lubricant on the head, the lubricant can flow back into the narrowed interface between the head and the disc, resulting a high static friction, or stiction between the head and the disc. If the disc drive motor does not have sufficient torque to overcome the stiction, the discs will become stuck, making repair or replacement of the disc drive necessary.
There is a need for disc drive technology which reduces the stiction to a small enough level so that the disc does not become stuck due to lubricant accumulation after periods of normal exercise or use.
SUMMARY OF THE INVENTION
In a disc drive with a disc spun by a motor and a head positionable over the disc, a disc drive controller alternately lands the head on the disc for a selected stop interval to remove an increment of lubricant from the head then automatically lifts the head by spinning the disc a run interval after the stop interval so the head does not stick to the disc.


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