1. Field of the Invention
The present invention relates to disk drives and more specifically, to a disk clamp for a disk drive that reduces debris migration onto the disk surface.
2. Description of Related Art
Work stations, personal computers and laptop computers require disk drives that provide a large amount of data storage within a minimal physical area. A disk drive typically includes one or more hard disks that are rotated at a constant high speed by a spindle motor. Generally, disk drives operate by positioning a transducer or read/write head over respective tracks on the disks. The information is written to and read from tracks on the disks through the use of an actuator assembly which rotates during a seek operation. The actuator is coupled to control electronics which control the positioning of the actuator and the read/write functions of the transducer. A typical actuator assembly includes a plurality of actuator arms which extend towards the disks with one or more flexures extending from each of the actuator arms. Mounted at the distal ends of each of the flexures is a head which acts as an air bearing enabling the head to fly in close proximity above the corresponding surface of the associated disk. The demand for increasing density of information stored on these disks is becoming greater and greater for a multitude of reasons. The increase of multi-user and multi-tasking operating system work stations which provide an operating environment requiring the transfer of large amounts of data to or from the hard disks, large application programs, the popularity of notebook and laptop computers and the continuing trend toward higher performance microprocessors all contribute to this end. The structural designs of these systems are also continually shrinking, requiring hard disk drives having high capacity storage capability while occupying a minimal amount of space within the system.
In order to accommodate these demands, there is a need for smaller hard disk drives which have increased storage capacity. To read this more densely stored information, engineers have decreased the gap fly height between the heads and the disks. Reducing the gap fly height leads to increased contact between a head and the data portion of the disk during operation of the disk drive. Nevertheless, there has been an industry wide push to reduce the height at which transducers are maintained over the disk surface without actually contacting the disk surface.
When a transducer flies over a rotating disk, the flying height tends to fluctuate slightly above and below a normal flying height because the disk surface itself is not flat. At lower flying heights the variation in the fly height may cause the transducer to contact the disk surface. This intermittent contact, if repeated, can damage the transducer or the disk and may cause drive failures.
In conventional disk drives, a stack of disks is provided on a cylindrical hub of a spindle motor. A disk clamp is provided on top of the stack of disks on the hub. The clamp has a larger radius than that of the hub so that the outer diameter of the clamp is in contact with the top disk. A plurality of screws, or a single screw, fit through holes located in the disk clamp. These screws (screw) are threaded into bores in the hub. When a screw is tightened, the force applied to the midsection of the disk clamp is transferred to the outer circumference of the disk clamp which contacts the disk surface. This force secures the disks to the spindle motor hub. The disks must be secured under considerable force in order to prevent any slippage of one or more disks in the presence of mechanical shocks. Even very slight slippage of a disk within a drive could result in mechanical misalignment of the transducer which could result in data transfer errors or failure.
The assembly of the disk clamp over the disk stack tends to generate minute particles which tend to disburse on the surface of the disks themselves. These small particles contribute to transducer contact with the disk surface, culminating in head crashes. The more fastening screws utilized to secure the disk clamp to the spindle motor, the more opportunity there is for the generation of these minute particles.
Accordingly, there is a need for a disk clamp that prevents dispersal of particles generated during assembly of the disk stack. The present invention provides a solution to this problem.