A typical data storage system includes one or more data storage disks coaxially mounted on a hub of a spindle motor. The spindle motor rotates the disks at speeds typically on the order of several thousand revolutions-per-minute. Digital information, representing various types of data, is typically written to and read from the data storage disks by one or more transducers, or read/write heads, which are mounted to an actuator assembly and passed over the surface of the rapidly rotating disks.
A conventional actuator assembly typically includes a plurality of outwardly extending arms onto which at least one head suspension assembly (HSA) is mounted at the extreme end of the arms. A typical HSA includes a load beam configured for mounting to the end of an actuator arm and a slider assembly onto which one or more read/write transducers are mounted. Airflow produced above and below the respective surfaces of the rapidly rotating disks results in the production of an air bearing upon which the aerodynamic slider is supported, thus causing the slider to fly a short distance above the rotating disk surface.
An actuator assembly configured to include a plurality of such outwardly extending arms is often termed an actuator comb. In operation, the actuator arms are interleaved into and out of the stack of rotating disks, typically by means of a coil assembly mounted to the actuator. The coil assembly generally interacts with a permanent magnet structure, and the application of current to the coil in one polarity causes the actuator arms and sliders to shift in one direction, while current of the opposite polarity shifts the actuator arms and sliders in an opposite direction.
In a typical digital data storage system, digital data is stored in the form of magnetic transitions on a series of concentric, closely spaced tracks comprising the surface of the magnetizable rigid data storage disks. The tracks are generally divided into a plurality of sectors, with each sector comprising a number of information fields. One of the information fields is typically designated for storing data, while other fields contain sector identification and synchronization information, for example. Data is transferred to, and retrieved from, specified track and sector locations by the transducers which are shifted from track to track, typically under the control of a data storage system controller. The transducer assembly typically includes a read element and a write element. Other transducer assembly configurations incorporate a single transducer element used to read and write data to and from the disks.
Writing data to a data storage disk generally involves passing a current through the write element of the transducer assembly to produce magnetic lines of flux which magnetize a specific location of the disk surface. Reading data from a specified disk location is typically accomplished by a read element of the transducer assembly sensing the magnetic field, or flux lines, emanating from the magnetized locations of the disk. As the read element passes over the rotating disk surface, the interaction between the read element and the magnetized locations on the disk surface results in the production of an electrical signal, often termed a readback signal, in the read element.
A trend has developed in the data storage system manufacturing community to miniaturize the chassis or housing of a data storage system to a size suitable for incorporation into miniature personal computers, such as notebook and pocket-sized computers, for example. Various industry standards have emerged that specify the external housing dimensions of small and very small form factor data storage systems. One such recognized family of industry standards is the PCMCIA (Personal Computer Memory Card Industry Association) family of standards, which specifies both the dimensions for the data storage system housing and the protocol for communicating control and data signals between the data storage system and a host computer system coupled thereto.
Recently, four families or types of PCMCIA device specifications have emerged. By way of example, a Type-I PCMCIA device must be fully contained within a housing having a maximum height dimension of 3.3 millimeters (mm). By way of further example, a Type-II PCMCIA device housing must not exceed a maximum height of 5.0 mm. A maximum height of 10.5 mm is specified for the housing of Type-III PCMCIA devices, and Type-IV devices are characterized as having a maximum housing height dimension in excess of 10.5 mm. It is anticipated that the industry trend toward continued miniaturization of data storage systems will eventually result in the production of systems complying with the Type-II PCMCIA specification. Such Type-II PCMCIA data storage systems will likely have external housing dimensions of approximately 54 mm.times.86 mm.times.5 mm, and include a data storage disk having a diameter of approximately 45 mm and a width dimension similar to that of a standard credit card.
It can be appreciated that a reduction in the housing dimensions of a data storage system necessarily results in a concomitant reduction in the size of the data storage disks disposed therein. It would appear desirable to increase the number of data storage disks disposed within the data storage system to provide for an increase in data storage capacity. This alternative, however, necessitates a reduction in axial spacing between adjacently stacked data storage disks which, in turn, necessitates a reduction in the thickness of the outwardly extending arms of the actuator assembly in order to accommodate the smaller disk-to-disk spacing. Although the thickness of the actuator arms must be reduced, the length of the actuator arms, however, must remain unchanged, thereby resulting in actuator arms having reduced stiffness characteristics.
The mechanical stiffness of an elongated actuator arm is generally a function of the arm's section modulus, configuration, and the material used to fabricate the arm, among other factors. It is generally considered critical that an actuator arm be sufficiently stiff in order to resist detrimental levels of bending or deflection which, in turn, can result in catastrophic contact between the actuator arm and the sensitive surface of a data storage disk. In particular, an actuator arm must generally be designed to resist detrimental levels of deflection in the presence of high-magnitude, short-duration, non-operational shock vibrations, in addition to resisting normal levels of deflection resulting from normal data storage system operation. It is noted that the packaging constraints imposed on the manufacturer's of compact data storage systems generally preclude employment of a conventional shock attenuation apparatus, thereby making such compact systems particularly susceptible to high-magnitude, short-duration shock vibrations.
It is well-understood that an elongated actuator arm becomes increasingly susceptible to such detrimental short-duration shock vibrations as its sectional modulus and, therefore, its stiffness is reduced. In addition to undesirable deflection characteristics, actuator arms having reduced stiffness are difficult to handle during actuator assembly fabrication. An actuator assembly that satisfactorily passes inspection after the actuator build process may subsequently be irreparably damaged by mis-handling the actuator assembly during installation into a data storage system. In order to increase the stiffness of actuator arms having reduced sectional moduli, it has been suggested that materials other than conventionally used materials be used in the fabrication of an actuator assembly. Such suggested alternative materials include ceramics, beryllium, beryllium alloys, and various other exotic alloys and composites. Although one or more of these suggested materials may appear to be suitable alternatives, none of these can be used to produce data storage system actuator assemblies in a cost-effective, high-yield manufacturing environment.
There exists in the data storage system manufacturing industry a keenly felt need to provide a shock-resistant actuator assembly suitable for use in systems having reduced disk-to-disk clearance specifications. There exists a further need for such an actuator assembly that can be reliably manufactured using conventional processes and at a relatively low-cost. The present invention fulfills these and other needs.