Dynamic magnetic information storage or retrieval – Monitoring or testing the progress of recording
Reexamination Certificate
2002-02-07
2003-11-11
Faber, Alan T. (Department: 2651)
Dynamic magnetic information storage or retrieval
Monitoring or testing the progress of recording
C360S053000, C360S097020, C360S075000
Reexamination Certificate
active
06646821
ABSTRACT:
FIELD OF THE INVENTION
This application relates generally to disc drives and more particularly to a disc drive leak detection system for a disc drive containing a low-density gas other than air.
BACKGROUND OF THE INVENTION
A disc drive typically includes a base to which various components of the disc drive are mounted. A top cover cooperates with the base to form a housing that defines an internal, sealed environment for the disc drive. The components include a spindle motor, which rotates one or more discs at a constant high speed. Information is written to and read from tracks on the discs through the use of an actuator assembly. The actuator assembly includes actuator arms, which extend towards the discs, with one or more flexures extending from each of the actuator arms. Mounted at the distal end of each of the flexures is a head, which includes an air bearing slider enabling the head to fly in close proximity above the corresponding surface of the associated disc.
Filling disc drives with low-density gases other than air (i.e., a gas having a density lower than air at similar pressures) can enhance their performance. For example, low-density inert gases such as helium can reduce the aerodynamic drag between the discs and their associated read/write heads by a factor of approximately five-to-one compared to operating in air. This reduced drag results in reduced power requirements for the spindle motor. A helium filled drive thus uses substantially less power than a comparable disc drive that operates in an air environment. At the same time, the helium gas conducts away heat generated during operation of the disc drive more effectively than air.
Despite the advantages of helium filled drives, such drives have not been commercially successful. This is mainly due to problems associated with the helium leaking from the disc drives over time. As the helium leaks out, air leaks in causing undesirable effects in the operation of the disc drives and possibly causing the disc drives to fail. For example, the increased concentration of air may increase the forces on the read/write head due to turbulent airflow within the drive and it may cause noise and/or the heads to fly at too great a distance above the discs. The risk of unexpected failure due to inadequate amounts of helium is a considerable drawback to helium disc drives, especially because the data stored within the disc drive can be irretrievably lost if the disc drive fails.
Accordingly there is a need for an improved drive that can effectively use helium without the risk of the disc drive unexpectedly crashing due to a low helium concentration. The present invention provides a solution to this and other problems, and offers other advantages over the prior art.
SUMMARY OF THE INVENTION
Against this backdrop the present invention has been developed. In accordance with one embodiment of the present invention, a method detects that a concentration of a low-density gas (such as helium) in a disc drive is in danger of reaching an unacceptable level. The method includes monitoring a signal that varies in response to variations in the concentration of the gas in the disc drive and determining a criterion based on the monitored signal. The criterion is chosen to indicate whether the disc drive is in danger of not performing satisfactorily due to a low concentration of the gas in the disc drive. This concentration is not necessarily unacceptable itself, but it indicates that the concentration is in danger of reaching an unacceptable level. The method also includes setting a flag when the criterion has been met. This flag may trigger a warning to the user or it may trigger other functions within the disc drive, such as automatically backing up the data from the disc drive.
Another embodiment of the present invention is a disc drive containing a low-density gas such as helium and including a gas leak detection system. The detection system includes a sensor within the drive producing a signal responsive to variations in the concentration of the gas in the disc drive. The sensor could be a read/write transducer and the signal could be an amplitude of the read signal representing the fly height of the transducer or a position error signal representing nonrepeatable runout. The signal may also represent the run current of a spindle motor or the measured disc mode vibrations of a separate accelerometer positioned on or within the disc drive.
The present invention can further be implemented as a disc drive including a housing containing a low-density gas other than air. The disc drive includes means for detecting whether the disc drive is in danger of not performing satisfactorily due to a low concentration of the gas in the disc drive. The detecting means preferably includes means for receiving a signal that varies in response to variations in the concentration of the low-density gas in the disc drive and a further means for determining whether a criterion based on the signal has been met.
These and various other features as well as advantages which characterize the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.
REFERENCES:
patent: 4514672 (1985-04-01), O'Gwynn
patent: 5798459 (1998-08-01), Ohba et al.
patent: 6144178 (2000-11-01), Hirano et al.
patent: 6167749 (2001-01-01), Yanagisawa et al.
patent: 0 635 785 (1995-01-01), None
patent: WO 96/10824 (1996-04-01), None
patent: WO 98/37548 (1998-08-01), None
Bernett Frank William
Fioravanti Louis J.
Merchant & Gould P.C.
Seagate Technology LLC
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