Mechanical isolation for a disc drive spindle motor

Details Mechanical isolation for a disc drive spindle motor Mechanical isolation for a disc drive spindle motor

1996-08-06

2003-01-21

Letscher, George J. (Department: 2653)

Dynamic magnetic information storage or retrieval

Record transport with head stationary during transducing

Disk record

Reexamination Certificate

active

06510021

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the field of disc drive data storage devices, and more particularly, but not by way of limitation, to improvements in mechanical isolation of a disc drive spindle motor to reduce the generation of acoustic noise and to suppress the effects of external mechanical shocks applied to the disc drive.
2. Discussion
Disc drives are commonly used in workstations, personal computers, portables and other computer systems to store large amounts of data in a form that can be made readily available to a user. In general, a disc drive comprises one or more magnetic discs that are rotated by a spindle motor at a constant high speed. The surface of each disc is divided into a series of data tracks which are spaced radially from one another across a band having an inner diameter and an outer diameter. The data tracks extends generally circumferentially around the discs and store data in the form of magnetic flux transitions within the radial extent of the tracks on the disc surfaces. Typically, each data track is divided into a number of data sectors that store fixed sized data blocks.
A head includes an interactive element such as a magnetic transducer which senses the magnetic transitions on a selected data track to read the data stored on the track, or to transmit an electrical signal that induces magnetic transitions on the selected data track to write data to the track. The head includes a read/write gap that positions the active elements of the head at a position suitable for interaction with the magnetic transitions on the data tracks of a disc as the disc rotates.
As is known in the art, each head is mounted to a rotary actuator arm and is selectively positionable by the actuator arm over a preselected data track of the disc to either read data from or write data to the preselected data track. The head includes a slider assembly having an air bearing surface that causes the head to fly over the data tracks of the disc surface due to fluid air currents caused by rotation of the disc.
Typically, several discs are stacked on top of each other and the surfaces of the discs are accessed by the heads mounted on a complementary stack of actuator arms which compose an actuator assembly, or “E-block”. The E-block generally includes head wires which conduct electrical signals from the heads to a flex circuit, which in turn conducts the electrical signals to a printed circuit board (PCB) mounted to a disc drive base deck.
As will be recognized, the general trend in the industry is to provide disc drives with ever decreasing form factors and ever increasing storage capacities. Along with increases in spindle motor rotation speeds, areal density of recorded data and faster data access times by disc drive actuator assemblies, customer expectations further include continued reductions in the level of acoustic emissions generated by modern disc drives, as well as the ability to withstand greater levels of externally generated operational and non-operational mechanical vibrations (also referred to as mechanical shocks).
Acoustic noise is typically generated by a disc drive from resonant vibrations induced in the disc drive housing by the operation of the spindle motor and the actuator assembly. A mechanical shock is provided to a drive through the handling of the drive or the system in which the drive is embedded. When an external mechanical shock is sufficiently severe, contact can be made between the internal components of the drive, causing damage to the surfaces of the discs or to the heads and flexures of the actuator assembly. Thus, the suppression of acoustic noise and the protection from external mechanical shock are related in that both involve controlling the transfer of mechanical energy to the drive housing, and both are important considerations in a disc drive design.
A variety of approaches have been proposed in the prior art to suppress the generation of acoustic noise and to protect disc drives against mechanical shock; for example, see U.S. Pat. No. 5,475,545 entitled METHOD FOR REDUCING NOISE DURING SEEKS IN A HARD DISC DRIVE issued Dec. 12, 1995 to Hampshire et al., which discloses shaping the velocity profile of an actuator assembly during the acceleration phase of a seek to reduce acoustic noise generated by the seek. Additionally, see U.S. patent application Ser. No. 07/673,967 entitled ACOUSTIC ISOLATOR FOR A DISC DRIVE ASSEMBLY, filed Mar. 22, 1991 by Morris et al., which discloses an acoustic compliance area surrounding the point of attachment of the spindle motor to the base deck to decrease the generation of acoustic noise and to protect against mechanical shocks. Both of these references are assigned to the assignee of the present invention and are incorporated herein by reference.
While the prior art has been effective, continued reductions in the size and continued increases in storage capacity requirements results in the need for improvements in the mechanical isolation of a disc drive. It is to such improvements that the present invention is directed.
SUMMARY OF THE INVENTION
The present invention provides an apparatus for mechanically isolating an excitation source, such as a disc drive spindle motor, to reduce the generation of acoustic noise by and to suppress the effects of external mechanical shocks upon a disc drive.
Accordingly, the disc drive includes a base deck having a central opening, the central opening having an interior surface. A mechanical isolator comprising an annular ring of compliant material is disposed within the central opening of the base portion so that an exterior surface of the mechanical isolator is connected to the interior surface of the central opening in the base portion. The mechanical isolator further includes a central opening having an interior surface to which an exterior surface of an inner support portion is attached, the inner support portion supporting the excitation source.
The mechanical isolator serves to isolate the inner support portion from the base portion of the base deck, damping the transfer of mechanical energy between the base portion and the support portion. In this manner, vibrations generated by the excitation source are damped before being transferred to the base deck, limiting the generation of acoustic noise by the drive. Moreover, mechanical shocks provided to the base deck are damped by the mechanical isolator so that reduced amounts of vibration are transferred to the spindle motor, reducing the risk of internal damage as a result of the mechanical shocks.
In a preferred embodiment, the mechanical isolator comprises vulcanized butyl rubber which is injection molded into place between the inner support portion and the remaining portions of the base deck. Additionally, teeth and corresponding grooves can be advantageously provided in the surfaces of the inner support portion and the base deck in order to increase the contact surface areas between these elements and the isolator.
An object of the present invention is to improve the ability of a disc drive to withstand the effects of external operational and non-operational mechanical shocks.
Still another object is to reduce the generation of acoustic noise by the disc drive.
Yet another object is to provide mechanical isolation for the drive in an inexpensive and easily manufacturable manner.
Other objects, advantages and features of the present invention will be apparent from the following description when read in conjunction with the drawings and appended claims.


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