Dynamic magnetic information storage or retrieval – Head mounting – Disk record
Reexamination Certificate
2002-03-06
2004-04-27
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
Disk record
C360S244300, C360S244500, C360S245200
Reexamination Certificate
active
06728072
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a head suspension assembly having a mounting region with an integral boss tower and to a multi-piece head suspension assembly with an integral boss tower.
BACKGROUND OF THE INVENTION
In a dynamic rigid disk storage device, a rotating disk is employed to store information. Rigid disk storage devices typically include a frame to provide attachment points and orientation for other components, and a spindle motor mounted to the frame for rotating the disk. A read/write head is formed on a “head slider” for writing and reading data to and from the disk surface. The head slider is supported and properly oriented in relationship to the disk by a head suspension that provides both the force and compliance necessary for proper head slider operation. As the disk in the storage device rotates beneath the head slider and head suspension, the air above the disk also rotates, thus creating an air bearing which acts with an aerodynamic design of the head slider to create a lift force on the head slider. The lift force is counteracted by a spring force of the head suspension, thus positioning the head slider at a desired height and alignment above the disk that is referred to as the “fly height.”
Head suspensions for rigid disk drives include a load beam and a flexure. The load beam includes a mounting region at its proximal end for mounting the head suspension to an actuator of the disk drive, a rigid region, and a spring region between the mounting region and the rigid region for providing a spring force to counteract the aerodynamic lift force generated on the head slider during the drive operation as described above. The flexure typically includes a gimbal region having a slider-mounting surface where the head slider is mounted. The gimbal region is resiliently moveable with respect to the remainder of the flexure in response to the aerodynamic forces generated by the air bearing. The gimbal region permits the head slider to move in pitch and roll directions and to follow disk surface fluctuations.
In one type of head suspension, the flexure is formed as a separate piece having a load beam-mounting region that is rigidly mounted to the distal end of the load beam using conventional methods such as spot welds. Head suspensions of this type typically include a load point dimple formed in either the load beam or the gimbal region of the flexure. The load point dimple transfers portions of the load generated by the spring region of the load beam to the flexure, provides clearance between the flexure and the load beam, and serves as a point about which the head slider can gimbal in pitch and roll directions to follow fluctuations in the disk surface.
The actuator arm is coupled to an electromechanical actuator that operates within a negative feedback, closed-loop servo system. The actuator moves the data head radially over the disk surface for track seek operations and holds the transducer directly over a track on the disk surface for track following operations.
The preferred method of attaching the head suspension to the actuator arm is swaging because of the speed and cleanliness of the swaging process. Swaging also provides a strong joint that resists microslip. The swaging process has been in use in rigid disk drives since the late 1960s for attaching head-suspension assemblies to actuator arms.
FIG. 1
is an exploded, isometric view of a conventional head stack assembly
10
including a load beam
12
, an actuator arm
32
and a discrete base plate
24
with a boss tower
28
. The head suspension assembly
10
includes a load beam
12
with a flexure
16
to which a head slider
20
having a read/write element or head is to be mounted. The load beam
12
includes a mounting region
14
at a proximal end, a rigid region
22
adjacent to a distal end, and a spring region
18
between the mounting region
14
and rigid region
22
. Spring region
18
is relatively resilient and provides a downward bias force at the distal tip of load beam
12
for holding the read/write head near a spinning disk in opposition to an upward force created by an air bearing over the disk. The flexure
16
is to allow pitch and roll motion of head slider
20
and read/write head as they move over the data tracks of the disk. The head suspension assembly
10
is typically coupled to the actuator via the actuator arm
32
that is attached to the mounting
14
region of load beam
12
.
A swage type attachment is used to couple the mounting region
14
of the load beam
12
to the actuator arm
32
. To swage load beam
12
to actuator arm
32
, actuator arm
32
and mounting region
14
include apertures
34
and
26
, respectively. The base plate
24
having a boss tower
28
with a swage hole
30
extending therethrough and, typically, a square flange
36
is welded or otherwise attached to a bottom face of mounting region
14
of load beam
12
. Boss tower
28
is then inserted through actuator arm aperture
34
. One or more swage balls are then forced through swage hole
30
in boss tower
28
causing boss tower
28
to expand in actuator arm aperture
34
. This expansion creates a frictional attachment interface between outside surface
66
of boss tower
28
and interior surface
68
of actuator arm aperture
34
. The load beam
12
typically includes one or more processing holes
38
useful for aligning the load beam
12
with the base plate
24
and/or actuator arm
32
. The base plate
24
and/or actuator arm
32
may optionally include corresponding processing holes
38
a
,
38
b
to facilitate alignment.
The design of the swage joint has been reduced in size to keep up with the miniaturization of disk drives. As the industry pushes to decrease disk spacing and to increase aerial spacing, the thickness of the base plate
24
and actuator arm
32
are constantly being decreased. However, recent moves to disk-to-disk spacing of under two millimeters have presented a severe problem. Miniaturization of the swage plates is not satisfactory because the torque-out capability that the swaged system drops too low to be useful.
What is needed is an attachment system that reduces head stack thickness without compromising torque-out capabilities.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to a head suspension assembly with a mounting region comprising an integral boss tower. The integral boss tower can be formed from material comprising the mounting region or as a separate component attached directly to the mounting region without a base plate. The integral boss tower eliminates the base plate and reduces the size of the head stack assembly, and hence, reduces disk spacing. The elimination of the base plate also reduces mass and inertia of the head suspension. The present integral boss tower can be used to mount a head suspension assembly to an actuator arm using industry-accepted standards.
The head suspension assembly comprises a load beam having a mounting region, a rigid region, and a spring region located between the mounting region and rigid region. The mounting region comprises an integral boss tower having an attachment feature. The integral boss tower can be formed from the material comprising the mounting region or attached directly to the mounting region without a base plate.
The mounting region, the rigid region, and the spring region can be a unitary structure. Alternatively, the mounting region and the rigid region can be separate components.
The present invention is also directed to a multi-piece head suspension assembly with an integral boss tower. In one embodiment, the mounting region and the rigid region comprise a first layer, and the spring region comprises a second layer in a multi-piece suspension. In another embodiment, the mounting region and the rigid region comprise a first layer, and the spring region and a flexure comprise a second layer in a multi-piece suspension. In yet another embodiment, the mounting region and the rigid region comprise a first layer, the spring region comprises a second layer, and the f
Bennin Jeffry S.
Christianson Mark R.
Fraser Brandon K.
Mahoney James R.
Marek Stevenson J.
Evans Jefferson
Faegre & Benson LLP
Hutchinson Technology Inc.
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