Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Disk record
Reexamination Certificate
2001-06-28
2003-10-21
Heinz, A. J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Disk record
Reexamination Certificate
active
06636379
ABSTRACT:
FIELD OF THE INVENTION
This application relates generally to disc drives for storing data and more particularly relates to an impaction filter that reduces the number of airborne particulates, while simultaneously reducing acoustic noise and mechanical vibrations within a disc drive housing.
BACKGROUND OF THE INVENTION
Efforts to miniaturize disc drives have resulted in disc drive designs that permit greater data storage density. Recent disc drive designs increase storage density by adding more discs to a disc drive and by increasing the track density of each disc. However, as the storage density increases, the disc drive's ability to position a read/write head above a particular track becomes more difficult and more critical.
One approach to increasing the ability of the disc drive to more accurately position the read/write head is to reduce internal and/or external mechanical vibrations that may affect the operation of the disc drive. Vibrations tend to cause the disc drive to incorrectly position the read/write head. When vibrations affect the positioning of the read/write head, remedial procedures must be taken to correct the positioning. Such measures cost precious seek time and can significantly reduce a disc drive's efficiency. Various attempts have been made to reduce internal and external vibrations that may affect the performance of a disc drive. However, these approaches generally require the addition of parts into the disc drive housing, thus frustrating the goal of disc drive miniaturization.
Vibrations also cause acoustic noise that may be perceivable by a disc drive user or may cause interference with other equipment. It is well known that the mechanical vibrations that cause perceivable acoustic noise can be generated by the movement of the disc. These mechanical vibrations are known to couple across the gap between the discs and the disc drive housing, thereby enabling the mechanical vibrations to emanate from the disc drive housing as acoustic noise. Acoustic noise is another reason that disc drive designers endeavor to reduce mechanical vibrations within a disc drive.
The presence of particulates within the housing of a disc drive is a well-documented phenomenon. If the particulates reside on the surface of a disc or otherwise interfere with the operation of the disc drive read/write head, such particulates can adversely affect the reading and writing operations of a disc drive. Moreover, as a disc spins within the disc drive housing, the disc causes air to flow, generally in a radial pattern with the spin direction of the disc. One problem caused by airflow in the disc drive housing is the transportation of particulates within the housing that can cause damage to the disc or interfere with the operation of the read/write head. The airflow can cause particulates to swirl within the housing and to collect on the disc and between the read/write head and the disc surface.
One approach to reducing the presence of particulates in the disc drive housing is to place filters in strategic locations within the disc drive housing. Such filters reduce the number of airborne particulates by filtering the air and slightly restricting airflow into the portion of the housing in which the disc resides. Unfortunately, the presence of other parts, such as the actuator arm, create tangential (i.e., not radial) airflow currents in the housing. Strategically positioned filters can fail to reduce particulates transported in the tangential airflow caused by parts other than the disc. Moreover, most filtration devices are solely directed at particulate filtration and do not reduce acoustic noise or mechanical vibrations in the disc drive housing.
FIG. 1
depicts a disc drive
100
equipped with a conventional particulate filtration system. The disc drive
100
includes a base
102
to which various components of the disc drive
100
are mounted. A top cover (not shown) cooperates with the base
102
to form an internal, hermetically sealed environment for the disc drive in a conventional manner. The primary disc drive components include a spindle motor
146
that rotates one or more discs
108
at a high speed. A disc shroud
150
can be formed in the base
102
, thereby providing space for the discs
108
and other disc drive components. The discs
108
can be one or more discs that are typically arranged in a vertically oriented disc pack. The vertical dimension of all of the discs in the disk pack is the disc pack height. Information is written to and read from tracks on the discs
108
through the use of an actuator assembly
110
, which rotates during a seek operation about a bearing shaft assembly
144
positioned adjacent the discs
108
. Mounted at the distal end of the actuator assembly
110
is a read/write head
118
. During a seek operation, the track position of the heads
118
is controlled through the use of a voice coil motor
124
.
A flex assembly
130
provides electrical connection paths for the actuator assembly
110
while allowing pivotal movement of the actuator assembly
110
during operation. The flex assembly includes a printed circuit board
132
to which head wires (not shown) are connected; the head wires being routed along the actuator assembly
110
to the heads
118
. The printed circuit board
132
typically includes circuitry for controlling the write currents applied to the read/write head
118
during a write operation and a preamplifier for amplifying read signals generated by the read/write head
118
during a read operation. The flex assembly terminates at a flex bracket
134
for communication through the base deck
102
to a disc drive control circuit board (not shown) mounted to the bottom side of the disc drive
100
. The drive control circuit provides a communication interface between the disc drive
100
and a host device (not shown), such as a personal computer. For example, the personal computer may request information that is contained on the disc or may send information to be stored on the disc.
The disc
108
, typically spins in the direction of arrow A. When the disc
108
rotates, airflow is generated by the rotation. Most of the airflow follows the radial direction of the disc and flows in the direction of arrows B and C. However, when the actuator arm
110
is extended toward the spindle motor
146
, a negative pressure can be created by the airflow and a tangential airflow can be created, for example, in the direction of arrow D. It is well known that particulates can exist within the disc drive housing. Particulates can be dust, lubrication, or any other unfixed matter that may be present in the disc drive housing. Such particulates can cause damage to the disc
108
, to the read/write head
118
, and generally adversely affect the operation of the disc drive
100
.
The disc drive
100
of
FIG. 1
is equipped with two, conventional filtration devices
136
,
140
. A fence filter
136
has a filter element
138
that is positioned substantially perpendicular to the flat surface of the disc
108
. The fence filter
136
is designed to catch particulates transported by radial airflow at the periphery of the disc
108
. The fence filter
136
also can catch particulates transported by tangential airflow at the periphery of the disc
108
, such as particulates carried in the direction of arrow D. However, the fence filter
136
is confined to a particular area of the disc drive housing and cannot collect particulates in radial or tangential airflow in other areas of the disc drive housing. A circulation filter
140
has a filter element
142
that is also positioned substantially perpendicular to the flat surface of the disc
108
. The circulation filter
140
is designed to catch particulates transported by radial airflow at the periphery of the disc
108
. The circulation filter
140
is incapable of catching particulates transported by tangential airflow at the periphery of the disc
108
. Moreover, the circulation filter
140
is confined to a particular area of the disc drive housing and cannot collect particulates
Rannow Randy K
Wong Walter
Heinz A. J.
Merchant & Gould P.C.
Seagate Technology LLC
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