Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Disk record
Reexamination Certificate
1999-08-03
2001-08-14
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Disk record
Reexamination Certificate
active
06275353
ABSTRACT:
FIELD OF THE INVENTION
This application relates generally to magnetic data storage devices and more particularly to a hard disc drive apparatus having reduced susceptibility to mechanical shock damage.
BACKGROUND OF THE INVENTION
Disc storage devices are used in data processing systems for storing large amounts of information that can be accessed in milliseconds. Storage or retrieval of information is accomplished by a disc drive system which includes one or more read/write (R/W) heads or “sliders” to read/write data from/to one or more discs.
A disc drive system stores data on rotating media, for example a magnetic disc, and uses read/write heads suspended on a moving armature which read/write the data on the rotating media as the surface of the rotating media moves past them. The interface between the heads and the disc surface is extremely delicate.
It is known that all physical parts of the disc drive system posses resonant vibrational modes, where, if a frequency equal to the resonant mode frequency is applied to the system, the part will resonate and amplify the initial exciting frequency. The spindle/disc pack also possesses such modes. When the spindle/disc pack is excited, typically by externally generated shock loads, it can generate a large amount of movement of the disc surface relative to the read/write heads. This prevents the heads from reading/writing the correct tracks on the disc surface and may result in the disc drive controller inhibiting a write or read, known as a write protect/write unsafe or a read protect/read unsafe. When the duration of the disturbance is prolonged, a write or read fault is declared, i.e. the disc drive indicates that it cannot write or read the data, despite repeated attempts. As a result, a fatal condition occurs. When the disc drive is properly mounted in a computer console or case, such impact loads are usually minimized. However, when the drive is removed or handled prior to installation in the cabinet bay or case, the situation is different. Dropping the drive can severely damage the delicate disc/head interface.
When a mechanical shock load is experienced by a hard disc drive, for example, by the user hitting the drive or dropping the drive prior to or during handling while installing the drive in the computer case or laptop computer, the spin motor in the hard disc drive receives this shock and transmits the shock received by the housing to the discs. If the frequency of the shock coincides with a resonance characteristic of the housing and/or the HDA, the transmitted shock load may be substantial. Since each of the sliders rests on the surface of one of the discs, the shock induced vibrations may cause surface to slider contact with potentially detrimental damage to the discs and/or sliders. Consequently, it is desirable to minimize the effects of external shock loads on the drive when the drive is not installed in the computer case or rack. One solution is to provide a rubber gasket between the base of the disc drive housing and the spin motor support in the disc drive housing, which dampens transmission of shock loads. However, this solution has the drawback of requiring additional assembly parts and therefore adds an additional cost to the apparatus.
Another problem that arises is one associated with the return of allegedly defective drives to the manufacturer. Sometimes a user/purchaser may drop a drive on the ground, then install the drive, and then find out that the drive no longer reads or writes data properly. The user then typically returns the drive to the dealer or manufacturer for a replacement drive. There is presently no built in mechanism in disc drives to accurately determine whether the drive has been subjected to unacceptably high shock loads during handling.
The present invention provides solutions to the above and other problems and offers advantages over the prior solutions to the above and other problems. These and various other features as well as advantages which characterize the present invention will be apparent upon reading of the following detailed description and review of the associated drawings.
SUMMARY OF THE INVENTION
The disc drive apparatus in accordance with the present invention incorporates a means for dampening shock loads to the disc drive housing by providing in the base plate structure of the housing itself a dampening means thus reducing the shock loads seen internally by the spin motor and thus reducing the shock loads to the disc/head interface. This may be done with or without providing a separate vibration damping spin motor mounting gasket between the base plate and the spin motor itself.
The disc drive in accordance with the present invention includes a base plate for supporting the head disc assembly (HDA) thereon and a cover fastenable to the base plate for enclosing the HDA on the base plate. A first embodiment of the invention has a cantilevered rail member formed in the base plate preferably on either side of the spin motor and preferably extending along the longer side edges of the base plate. Typically, these rails are used to mount the drive in a drive bay in a computer case via screws placed in appropriately spaced holes in the rails. These cantilevered rail members are formed by providing a horizontally open slot in each rail extending longitudinally either in the outer face or the inner face of the rail.
A second embodiment of the disc drive in accordance with the invention includes a base plate having a longitudinal side rail extending downward from each side of the rectangular base plate along each long edge of the rectangular base plate and at least one through slot extending longitudinally through the side rail. Since the disc drive is typically mounted into a computer case via screws in screw holes through the side rails, the longitudinal through slot is preferably spaced between the screw holes.
In another embodiment of the present invention, an open longitudinal slot may be cut through each of the ends of the side rails so as to form a thin tongue of rail at each rail end. If the drive is dropped onto a hard surface, for example, the drive typically will not land squarely on its top, bottom, or side. Instead, one of the corners will strike the hard surface first. Since, in this embodiment, a thin tongue of rail exists at each end of the rail and thus at each corner of the base plate, it will likely strike the hard surface and deform or break. This serves two purposes. First, the tongue deformation or breakage absorbs at least part of the impact load. Second, the deformation can be detected upon return of the “defective” drive as evidence of the drive having been subjected to an excessive load. The location, length, and thickness of the rail tongue or finger can be selected such that an acceptable shock load will not deform the tongue, but an excessive load will. Thus the second purpose is to provide an indicator of excessive shock loading.
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: 5305180 (1994-04-01), Mitchell et al.
patent: 5662482 (1997-09-01), Shin
patent: 5717575 (1998-02-01), Copeland et al.
patent: 5941552 (1999-08-01), Beran
patent: 6005768 (1999-12-01), Jo
patent: 6078498 (2000-06-01), Eckerd et al.
patent: 8-7426 (1996-01-01), None
Evans Jefferson
Merchant & Gould
Seagate Technology LLC
Wahl John R.
LandOfFree
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