Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Disk record
Reexamination Certificate
1999-11-19
2001-09-11
Ometz, David L. (Department: 2652)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Disk record
Reexamination Certificate
active
06288866
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to disk drives. More particularly, this invention pertains to a disk drive that includes a vibration damping system having a compressible foam and mass damper fixed adjacent to the outer surface of a printed circuit board for reducing noise and vibration.
2. Description of the Prior Art
Disk drives are commonly employed in workstations, personal computers, portables and other computer systems to store large amounts of data in a readily-available form. Typically, the primary components of a hard disk drive are a head disk assembly and a printed circuit board assembly. When fixed to one another, they form a functional unit for insertion into a bay of a host computer.
The head disk assembly includes a base casting and a cover, a disk having a recording surface, a spindle motor for causing the disk to rotate and an actuator arrangement, driven by a voice coil motor, for advancing a read/write head. A flex circuit transmits data signals to and from the read/write head of the actuator.
The printed circuit board assembly includes circuitry for processing signals and controlling operations of the drive. A representative disk drive incorporating the structures referred to herein is taught, for example, in U.S. Pat. No. 5,790,348 of Alfred et al. entitled “Head Stack Assembly Having a Coil Portion for Damping Vibration Which Includes Elongated Openings in the Plastic Portion.” Such patent, property of the assignee herein, is hereby incorporated by reference.
The operation of a hard disk drive necessarily generates structural noise and vibration. Both the electromagnetic spindle and the electromechanical voice coil motors drive the device with the spindle motor continually rotating the storage disk(s) and the voice coil motor selectively driving the actuator(s) to position the read/write heads in the “seek” mode. The motors transmit resonances throughout the disk drive, creating structural vibrations and acoustical, audible noise of varying frequencies. Such noise is transmitted to the substantially-planar printed circuit board which, in turn, can amplify resonant frequency sound intensity, acting, in effect, as a speaker diaphragm.
The presence of acoustic noise in an operating disk drive is undesirable. Customers perceive loudness as an indication of lower quality. As such, acoustic characteristics serve as a benchmark of product quality. Increases in spindle motor speeds intensify the noise transmitted by the head disk assembly to the printed circuit board assembly. Acoustics standards, such as those of the internationally-recognized European International Standards Organization (“ISO”), are regularly lowered, forcing manufacturers to design disk drives characterized by reduced acoustic noise.
SUMMARY OF THE INVENTION
The invention can be regarded as a disk drive that includes a head disk assembly having a base casting that comprises a sidewall defining a base area within the peripheral edge of the assembly. A planar printed circuit board includes opposed inner and outer surfaces. The board is fixed within the base area of the assembly so that the inner surface of the printed circuit board faces the assembly.
A vibration damping system for reducing noise and vibration associated with operation of the disk drive is fixed adjacent the lower surface of the board and substantially underlies the base area. The system includes an external planar member of compressible foam composition characterized by an unconstrained thickness d
1
having opposed upper and lower surfaces as well as a substantially-planar, rigid mass damper. The mass damper has major upper and lower surfaces.
The external planar member and the mass damper are of like extent and shape and are arranged in an overlapping configuration. The upper surface of the external member contacts the outer surface of the printed circuit board while major upper surface of the mass damper contacts the lower surface of the external member. Means are provided for fixing the upper surface of the mass damper in substantially-uniform spaced relationship from the outer surface of the printed circuit board by a predetermined amount that is less than d
1
, thereby compressing the external member.
REFERENCES:
patent: 5060100 (1991-10-01), Mihara et al.
patent: 5282099 (1994-01-01), Kawagoe et al.
patent: 5282100 (1994-01-01), Tacklind et al.
patent: 5394306 (1995-02-01), Koenck et al.
patent: 5596483 (1997-01-01), Wyler
patent: 5757580 (1998-05-01), Andress et al.
patent: 5982580 (1999-11-01), Woldemar et al.
patent: 406126872-A (1994-05-01), None
Butler Walter W.
Cheng Chunjer C.
Altman, III Franklin D.
Kim W Chris
Ometz David L.
Shara Milad G
Western Digital Technologies Inc.
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