Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Disk record
Reexamination Certificate
2001-07-31
2004-02-24
Heinz, A. J. (Department: 2652)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Disk record
Reexamination Certificate
active
06697216
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to disk drives. In particular, it is directed to disk drives in which the head is located upstream of the actuator arm.
BACKGROUND OF THE INVENTION
Disk drives are data storage devices that are commonly used in many applications. In a typical hard-disk drive, a disk enclosure houses a spindle that supports and spins a stack of disks and an actuator that positions a comb of head-carrying assemblies. At least one transducer element, (referred to here as a head) reads and/or writes data to and/or from each disk and is carried by each head-carrying assembly.
One of the challenges of disk-drive design is to maintain the head at a very precise location that is preferably a very small fixed distance above the disk. Variations in the height of the head from the disk, the radial location of the head over the disk, and the roll and pitch angles of the head increase the probability of read/write errors. An exceptional design would hold the head at a fixed height and orientation above the disk regardless of any conceivable disturbance.
Modern disk-drive design attempts to achieve these goals through the use of an air-bearing slider designed to fly over the spinning disk. The head is either formed as part of the slider, or is mounted to it. As the disk spins, the air adjacent to the disk is induced to rotate substantially with the disk. The slider flies in the induced flow. The aerodynamic forces generated on the slider are generally balanced by a suspension to which the slider is attached. A balance between the design aerodynamic forces on the slider and the restoring elastic forces imposed by the suspension helps to maintain the slider, and hence the head, at the desired fly height and angle.
Traditional disk drives are arranged as shown in
FIG. 1. A
shroud
105
partially encloses at least one disk
100
that is supported by a spindle
150
that rotates the disks. For convenience,
FIG. 1
shows only a single disk although many more may be part of the disk stack. The disk
100
spins in a spinning direction
120
. The air between adjacent disks (or if no adjacent disk exists, in the vicinity of the disk
100
) is dragged with the disk
100
, thereby inducing a flow
125
that rotates substantially with the disk
100
. The head-carrying assembly
200
is comprised of an actuator arm
210
, a suspension
230
, and a slider, which is not shown in
FIG. 1
, but which would be attached to the suspension
230
in the vicinity of the distal end
204
of the head-carrying assembly
200
. As mentioned earlier, a head would be mounted on, or be integral with, the slider. To position the head over the disk
100
, the head-carrying assembly
200
is usually designed to rotate about a point in the vicinity of its proximal end
202
. A rotary actuator rotates the head-carrying assembly
200
in response to signals received from an actuator electronics package, which determines exactly how much the head-carrying assembly
200
must rotate for the head to reach the desired position. Linear actuators, in which the head-carrying assembly is moved linearly to position the head over a desired radius of the disk, are currently less commonly used.
In the traditional configuration, the introduction of the head-carrying assembly
200
into the flow induced by the disk
100
distorts the substantially solid-body rotation of the flow. As seen in
FIG. 1
, the head-carrying assembly
200
blocks the smooth passage of the air. (As used herein, the word “air” denotes whatever fluid is between the disks.) The bulk of the air is channeled through the gap between the spindle
150
and the distal end
204
of the head-carrying assembly
200
. Most of the remaining air is deflected outwardly. In practice, a small portion of the air will also squeeze between the head-carrying assembly
200
and the disk
100
or an adjacent disk (not shown) in the disk stack.
The traditional arrangement causes a number of problems. The flow that is channeled through the gap between the spindle
150
and the distal end of the head-carrying assembly
204
is traveling faster than the disk
100
. Because turbulent fluctuations typically scale with flow speed, the increased speed likely implies increased turbulent fluctuation amplitude, and hence larger excitations of the head. In addition, some of the flow channeled through the gap has flowed alongside the edge of the head-carrying assembly
200
for an extended period of time. Turbulence created by the complicated interaction of the flow with the head-carrying assembly
200
will be swept along the suspension
230
and produce additional unsteadiness, which must be damped. The situation is dramatically worsened by the fact that the flow expands rapidly upon exiting the gap between the spindle
150
and the distal end
204
of the head-carrying assembly
200
, thereby producing very high-intensity turbulent fluctuations in the vicinity of the head.
One way to circumvent this problem is to position the head upstream of the actuator arm. Positioning one head upstream of the actuator arm is disclosed as a side effect in various prior patents that employ multiple head-carrying assemblies between adjacent disks.
U.S. Pat. No. 5,218,496 to Kaczeus shows a pair of angularly offset head-carrying assemblies disposed between adjacent disks. The head on one head-carrying assembly magnetically cooperates with the lower surface of the upper disk and the head on the other head-carrying assembly magnetically cooperates with the upper surface of the lower disk. The patent mentions that the orientation of the sliders that support the heads on each head-carrying assembly is reversed in the design.
In U.S. Pat. No. 5,343,347 to Gilovich, a disk drive is disclosed in which the positioning relative to the flow between the disks of some heads and actuator arms are reversed from that of others. Gilovich does not address which of the heads are upstream of their actuator arms and which are downstream, nor does he address the fluid-mechanical implications of altering the upstream/downstream relationship between the heads and the actuator arms.
However, in U.S. Pat. No. 6,057,990, also to Gilovich, he indicates that a weakness in his earlier work was that in most cases at least two different and distinct heads would be required (column 1, lines 48-57). He states that he believes that no manufacturer in the industry constructs a transducer head that would accommodate a disk rotating clockwise with a head to the right of the spindle or a disk rotating counterclockwise with a head to the left of the spindle (column 1, lines 28-34). Analysis of these configurations reveals that such orientations correspond to situations in which the head is upstream of the actuator arm.
SUMMARY OF THE INVENTION
Considerable effort has been expended devising schemes to dampen the effects that the turbulent fluctuations have on vibrations of the head. In the current invention, exceptional reduction of head vibration is achieved by decreasing the turbulent fluctuations encountered by the head. Reorienting the head-carrying assembly relative to the flow induced by the spinning disks reduces the turbulent fluctuations.
The reoriented configuration is illustrated schematically in FIG.
2
. In the novel configuration, the head-carrying assembly
200
is oriented such that, relative to the induced flow
125
, each head (not explicitly shown, but ordinarily carried by the suspension
230
) is disposed upstream of its actuator arm
210
. The prior art discussed above shows some, but not all, of the heads oriented upstream of their respective actuator arms. The current invention is distinguished from the prior art by requiring that each head-carrying assembly
200
is oriented with its head upstream of its actuator arm
210
.
Alternatively, the reoriented configuration can be described by considering the angle between two lines. A first line extends from the disk center
110
to the distal end
204
of the head-carrying assembly
200
. A second line extends from the disk center
110
to the pi
Hirano Toshiki
Lee Francis C.
Pan Tzong-Shii S.
Zeng Qinghua
Heinz A. J.
Hitachi Global Storage Technologies
Lumen Intellectual Property, Inc.
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