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 disk drive are a head disk assembly and a printed circuit board assembly which when fixed to one another form a functional unit that is then connected to a computer, such as by insertion into a bay of a host computer.
The head disk assembly includes a base and a cover which collectively house a head stack assembly and a data storage disk mounted on a spindle motor assembly for rotating said storage disk, 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 operation of a hard disk drive necessarily generates noise such as airborne and structure borne noises. For example, the electromagnetic spindle and the electro-mechanical 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. The motors transmit structural vibrations throughout the disk drive, for example the cover and the printed circuit board, creating audible noise of varying frequencies.
The presence of acoustic noise in an operating disk drive is undesirable. Users perceive loudness as an indication of lower quality. As such, acoustic characteristics may serve as a benchmark of product quality. Furthermore, the ever-increasing operational speed of computers mandates reductions in the data access time from disk drives, resulting in increases in the speed of spindle motor and the actuator which in turn intensifies the overall disk drive noise. In addition, disk drive customers present increasingly challenging acoustic requirements, forcing manufacturers to design disk drives characterized by reduced acoustic noise.
Currently, one form of reducing the noise associated with the operation of a disk drive is by use of damping materials. Typically, a layer of damping material, such as a foam material, is located in various regions of the disk drive, such as in between the printed circuit board and the head disk assembly to reduce the associated amplification of the noise by the printed circuit board. One example of the damping material is a layer of adhesive material inserted between the base assembly (of the head disk assembly) and the circuit board, as described in the U.S. Pat. No. 5,235,482 entitled “Magnetic disk drive incorporating a mechanically damped base”, herein incorporated by reference. Although increasing the thickness of damping material could improve acoustic damping, disk drive form factor standards limit the thickness of damping materials which can be used.
Accordingly, what is needed is a noise-damping device that allows for dampening the noise generated by the operation of the disk drive while minimizing the need for increased thickness of the noise-damping device.