Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Disk record
Reexamination Certificate
2000-02-17
2002-04-02
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Disk record
C360S135000
Reexamination Certificate
active
06366426
ABSTRACT:
FIELD OF THE INVENTION
This application relates to magnetic disc drives and more particularly to a disc drive having a component or components that incorporate a laminate damping material.
BACKGROUND OF THE INVENTION
Disc drives are data storage devices that store digital data in magnetic form on a rotating storage medium on a disc. Modern disc drives comprise one or more rigid discs that are coated with a magnetizable medium and mounted on the hub of a spindle motor for rotation at a constant high speed. Information is stored on the discs in a plurality of concentric circular tracks typically by an array of transducers (“heads”) mounted to a radial actuator for movement of the heads relative to the discs. Each of the concentric tracks is generally divided into a plurality of separately addressable data sectors. The read/write transducer, e.g. a magnetoresistive read/write head, is used to transfer data between a desired track and an external environment. During a write operation, data is written onto the disc track and during a read operation the head senses the data previously written on the disc track and transfers the information to the external environment. During either the read or write operation it is imperative that the head maintain a centered position within the desired track. An off-centered head will have lower overall reliability where the head has a higher likelihood of improperly performing the reading and writing operations.
Critical to maintaining proper head positioning within the center of a concentrically circular track is minimizing structural vibrations within the disc drive, especially vibrations that effect the stability of the information storage discs. Structural vibrations are introduced into the disc of a disc drive by such normal operating conditions as the rotation of the spindle motor, air turbulence around the outer diameter of the rotating discs and by other normal events that can cause pulse forces to transmit to the disc or originate at the disc. Additionally, non-operational vibrations may also be introduced to the disc by shock events like dropping or kicking the computer. In either case, normal operating conditions or shock events, a need exists to minimize structural vibrations in the disc so as to maintain the integrity of the head position at the center of a desired track.
Conventionally, discs are typically produced from stamped aluminum alloy substrate. Aluminum alloy as a disc substrate is cost effective, clean and facilitates ease of manufacture. However, aluminum alloys, like most structural metal alloys, exhibits negligible properties for limiting or damping structural vibrations. Two possible solutions for damping structural vibrations within a disc are to use an extrinsic damping material on the disc or to incorporate an intrinsic damping material within the disc.
An external damping material could be used to dampen structural vibrations within the metal components of a disc drive. This solution would require proper spacing to be maintained throughout the disc drive as well as effective positioning of the material on the relevant components.
An alternative solution to extrinsic damping is to intrinsically dampen the information storage disc. The industry standard for intrinsically damping information storage disc substrates is to adhere or laminate viscoelastic polymeric materials with the aluminum alloy substrate. This method of intrinsically damping the disc substrate, however, has several key shortcomings, including: (1) the adhered polymers tend to creep under the centrifugal acceleration forces of the rotating spindle. The creeping polymer tends to introduce variations in the thickness of the disc and, as a result, introduce surface distortions that have an adverse effect on the reliability in the read and write operations in the disc drive; and (2) adhesives and polymers tend to “outgas” over time and with use. Outgassing is a major concern of the disc drive industry, as outgassing tends to accelerate the rate of generation of corrosion products within the disc drive assembly. Further, outgassed hydrocarbons tend to build-up on the head and disc surfaces and can interfere with the head flying over the disc surface.
Accordingly, there is a need for a damped disc substrate that avoids the added cost and complexity of extrinsic damping materials and avoids the shortcomings of current intrinsic damping materials, yet absorbs the energy of structural vibrations and enhances overall disc drive reliability. Note also, that although the proceeding example focused on aluminum based information storage disc substrates, the same need exists for dampening structural vibrations within any of the structural components of the disc drive assembly.
SUMMARY OF THE INVENTION
Against this backdrop the present invention has been developed. The present invention is a structural component of a disc drive that incorporates a fusible alloy portion to dampen structural vibrations in the disc drive.
In accordance with the preferred embodiment of the present invention, a damped structural component in a disc drive includes a first structural alloy portion, a second structural alloy portion and a fusible alloy portion. The fusible alloy portion is sandwiched between the first and second structural alloy portions to operatively dampen structural vibrations felt by the structural component. The structural component may be an information storage disc, base plate or any structural component found within the disc drive.
The present invention can further be implemented as a method for reducing structural vibrations in a structural component of a disc drive. The method includes the steps of providing a first structural component portion, providing a second structural component portion, sandwiching a fusible alloy portion between the first and second structural component portions and joining together the first structural component portion, the fusible alloy portion and the second structural component portion.
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.
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Beatty Paul A.
Murphy James M.
Olivero David A.
Thomas Patrick M.
Wong Walter
Evans Jefferson
Prendergast Paul J.
Seagate Technology LLC
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