U.S. patent application number 09/158647 was filed with the patent office on 2002-03-07 for an improved gimbal for a head of a disc drive with vertical limiter.
Invention is credited to BUDDE, RICHARD A..
Application Number | 20020027747 09/158647 |
Document ID | / |
Family ID | 26738766 |
Filed Date | 2002-03-07 |
United States Patent
Application |
20020027747 |
Kind Code |
A1 |
BUDDE, RICHARD A. |
March 7, 2002 |
AN IMPROVED GIMBAL FOR A HEAD OF A DISC DRIVE WITH VERTICAL
LIMITER
Abstract
A base mounting portion connects the gimbal spring to a load
beam and thereby to the actuator of the disc drive which positions
the gimbal and slider over a desired track on the disc. The gimbal
includes opposed spaced flexure arms which are formed of elongated
members, each having a proximal end and a distal end which define
an opening therebetween. The proximal ends of the flexure arms are
operably coupled to the base, and the distal ends are cantilevered.
A mounting tab is positioned between the ends of the flexure arms
and supports the slider. Bridge sections are provided which connect
the distal ends of the flexure arms to the mounting tab, the bridge
sections extending at an angle relative to the flexure arms and
being angled back toward the base section of the gimbal. The bridge
sections support a limiter extending over said load beam to limit
vertical movement of said load beam.
Inventors: |
BUDDE, RICHARD A.;
(PLYMOUTH, MN) |
Correspondence
Address: |
MR. JAMES A. SHERIDAN
THOMASON, MOSER & PATTERSON LLP
4149-B E1 CAMINO WAY
PALO ALTO,
CA
94306-4036
US
|
Family ID: |
26738766 |
Appl. No.: |
09/158647 |
Filed: |
September 22, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60059451 |
Sep 22, 1997 |
|
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Current U.S.
Class: |
360/245.7 ;
G9B/5.151 |
Current CPC
Class: |
G11B 5/4826
20130101 |
Class at
Publication: |
360/245.7 |
International
Class: |
G11B 005/48 |
Claims
What is claimed is:
1. A gimbal spring adapted to flexibly support a slider relative to
a disc surface for operation comprising: a base mounting portion
adapted to operably connect the gimbal spring relative to a load
beam and thereby to an actuation system; opposed spaced flexure
arms extending from the base, said flexure arms being formed of
elongated members each having a proximal end and a distal end
defining an elongated extent therebetween, said proximal end being
operably coupled to the base and said distal end being cantilevered
relative to the base; a mounting tab adapted to connect to a
slider, said mounting tab being positioned between the spaced
flexure arms and ends of the mounting tab being spaced a distance
from said flexure arms; bridge sections adapted to connect the
distal ends of the flexure arms to the mounting tab, the bridge
extending from the distal end of the flexure arms toward the
proximal end at a sloped angle relative to said flexure arms to
connect a distal end of the flexure arm relative to the mounting
tab; and a limiter supported by said bridge sections to restrain
vertical movement of said gimbal.
2. The gimbal spring of claim 1 wherein the gimbal spring is
adapted to support a slider supporting an optical lens.
3. The gimbal spring of claim 2 wherein the limiter lies over a
vertically opposed sides of said load beam from said gimbal
spring.
4. The gimbal spring of claim 2 wherein said bridge sections
supporting a slider mounting tab including a surface opposite to
that faced by said limiter and contacting a simple on said
slider.
5. In a head suspension assembly including a load beam supporting a
gimbal spring having a load button at an extended end of the
gimbal, a slider having a leading edge and a trailing edge, said
gimbal spring having a base mounting portion operably coupled to
the load beam and a mounting tab operably coupled to the slider,
and opposed spaced flexure arms each having a proximal end and a
distal end, the proximal end of the flexure arms being coupled to
the base mounting and the mounting tab being operably coupled to a
distal end of the flexure arms to flexibly support the slider
relative to the load beam, the gimbal spring being coupled to the
load beam and adapted to support the slider so that the load button
provides a load force to the slider at a pivot axis of the slider
relative to the gimbal spring, and a limiter supported between said
flexure arms and overlying said load beam to restrain vertical
movement.
6. The head suspension assembly of claim 5 wherein the pivot axis
is positioned in a center portion of the slider between the leading
and trailing edges.
7. The head suspension assembly of claim 5 wherein the gimbal
spring is adapted to support the slider supporting an optical
lens.
8. The head suspension assembly of claim 5 wherein the mounting tab
is positioned proximal of the distal end of the flexure arms and is
operably coupled to the distal end of the flexure arms by bridges
extending from the distal end of the flexure arms toward the
proximal end, the slider being supported on an opposite side of
said load beam from said limiter.
9. The assembly of claim 8 wherein said limiter is supported
between said bridge arms to extend over said load beam.
10. The assembly of claim 9 wherein said limiter is supported from
the rear of said mounting tab.
11. The head suspension assembly of claim 5 wherein the mounting
tab is coupled to the slider at the pivot axis.
12. The head suspension assembly of claim 11 wherein the mounting
tab is an elongated rectangular shaped member having opposed ends
adapted to couple to an upper surface of the slider and extending
between opposed sides of the slider where opposed ends are aligned
with opposed sides of the slider, and where the mounting tab is
depressed relative to a plane established by said flexure arms.
13. In a head suspension assembly including a load beam supporting
a gimbal spring having a load button at an extended end of the
gimbal, a slider having a leading edge and a trailing edge, said
gimbal spring having a base mounting portion operably coupled to
the load beam and a mounting tab operably coupled to the slider,
and opposed spaced flexure arms each having a proximal end and a
distal end, the proximal end of the flexure arms being coupled to
the base mounting and the mounting tab being operably coupled to a
distal end of the flexure arms to flexibly support the slider
relative to the load beam, the gimbal spring being coupled to the
load beam and adapted to support the slider so that the load button
provides a load force to the slider at a pivot axis of the slider
relative to the gimbal spring, wherein the improvement comprises:
means for supporting the slider and allowing pitch and roll around
and along said pivot axis; and means for limiting vertical movement
of said load beam.
14. A head suspension assembly as claimed in claim 13 wherein said
supporting means comprise bridge means supporting said means for
supporting the slider and means for limiting vertical movement of
said load beam.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to U.S. Provisional Patent
Application Serial No. 60/059,451, filed Sep. 22, 1997, and
entitled DEFLECTION LIMITER FOR AN OPTICALLY ASSISTED WINCHESTER
DRIVE.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a disc drive assembly. In
particular, the present invention relates to an improved suspension
design for supporting a head relative to a disc surface.
[0003] Disc drive systems are known which read data from a disc
surface during operation of a disc drive. Such disc drive systems
include conventional magnetic disc drives and optical disc drive
systems. Optical disc drive systems operate by focusing a laser
beam onto a disc surface via an optical assembly which is used to
read data from the disc surface. Conventional magnetic disc drive
systems use inductive type heads for reading or writing or
magneto-resistive (MR) heads for reading data. Discs are rotated
for operation of the disc drive via a spindle motor to position
discs for reading data from or writing data to selected positions
on the disc surface.
[0004] Known optical assemblies include an objective lens which is
positioned between the objective lens and the disc surface. The SIL
is positioned very close to the data surface of the disc and is
described in U.S. Pat. No. 5,125,750 to C. Orle et al., which
issued Jun. 30, 1992, and in U.S. Pat. No. 5,497,359 to Mamnin et
al., which issued Mar. 5, 1996. In these optical systems, a laser
beam is focused onto the SIL using an objective lens. The SIL is
preferably carried on a slider and the slider is positioned close
to the disc surface. Use of an SIL increases storage density.
[0005] The slider includes an air bearing surface to fly the SIL
above the disc surface. The slider includes a leading edge and a
trailing edge. Rotation of discs creates a hydrodynamic lifting
force under the leading edge of the slider to lift the leading edge
of the slider to fly above the disc surface in a known manner. The
slider preferably flies with a positive pitch angle in which the
leading edge of the slider flies at a greater distance from the
disc surface than the trailing edge via a suspension assembly which
includes a load beam and gimbal spring. The slider is coupled to
the load beam via the gimbal spring. The load beam applies a load
force to the slider via a load button. The load button defines an
axis about which the slider pitches and rolls via the gimbal
spring. The slider is preferably resilient in the pitch and roll
direction to enable the slider to follow the topography of the
disc.
[0006] The flexure of the gimbal spring permits the air bearing
slider to pitch and roll as the slider flies above the disc
surface. It is important to maintain the proximity of the SIL and
slider relative to the disc surface to maintain the proper focus of
light onto the disc surface as is known for optical disc drive
systems. It is important that the flexure system including the load
beam and the gimbal spring be designed to stably and accurately
support the slider during operation of the disc drive system. In a
magneto-optic (M-O) system, a magnetic transducer element is
carried on the slider to write data to the disc surface. It is also
important to accurately support and position the magnetic
transducer elements relative to the disc surface during operation
of an M-O system.
[0007] An actuator mechanism is coupled to the suspension assembly
to locate the SIL relative to selected disc positions for operation
of the disc system. During movement of the suspension system, force
is transmitted through the load beam and gimbal spring to move the
slider. Operation of the actuator mechanism, air bearing surface,
and spindle motor introduce external vibration to the slider and
suspension assembly. Depending upon the mass and stiffness of the
suspension assembly, including the gimbal spring and load beam,
external vibration may excite the load beam and gimbal spring at a
resonant frequency. Thus the input motion or external vibration may
be amplified substantially, causing unstable fly characteristics
and misalignment of the slider relative to the disc surface.
[0008] External vibration or excitation of the suspension assembly
and slider may introduce varied motion to the slider and suspension
assembly. Depending upon the nature and frequency of the excitation
force, the slider and suspension assembly may cause torsional mode
resonance, sway mode resonance, and bending mode resonance.
Torsional mode motion relates to rotation or twisting of the
suspension assembly about an in-plane axis. Bending mode resonance
essentially relates to up-down motion of the suspension assembly
relative to the disc surface. Sway mode vibration relates to
in-plane lateral motion and twisting. It is important to limit
resonance motion to assure stable fly characteristics for the SIL.
In particular, it is important to control the torsion and sway mode
resonance, since they produce a transverse motion of the slider,
causing head misalignment with respect to the data tracks on the
disc surface.
[0009] The resonance frequency of the suspension assembly is
related to the stiffness or elasticity and mass of the suspension
system. Thus, it is desirable to design a suspension system which
limits the effect of sway mode and torsion mode resonance in the
operating frequencies of the disc drive while providing a
suspension design which permits the slider to pitch and roll
relative to the load button, and which has relatively high lateral
rigidity and stiffness for maintaining precise in-plane positioning
of the slider along the yaw axis.
[0010] It is also highly desirable to incorporate a deflection
limiter in the design of the suspension assembly.
[0011] Deflection limiters are beneficial for several reasons.
During a shock event, such as dropping the disc drive or HGA
shipping tray, the mass of the head and lens can pull the gimbal
away from the load beam if there is no deflection limiter. This
deflection will induce stress in the gimbal. The stress could be
high enough to yield the gimbal and result in dimple separation and
changes to the pitch and roll static angle of the gimbal. A
deflection limiter will prevent this from happening by ensuring
that the deflection is not large enough to cause the stress to
reach the yield point. Deflection limiters are also beneficial for
ramp load/unload applications, especially with negative pressure
air bearings.
SUMMARY OF THE INVENTION
[0012] Thus it is an object of the present invention to provide an
improved suspension system for a disc drive. More specifically, it
is an objective to provide an improved suspension design which
utilizes a simplified design approach to providing a deflection
limiter in a suspension system.
[0013] A further object of this invention is to provide an improved
suspension which limits the resonance motion and the vertical
travel of the gimbal to assure stable flying characteristics for
the gimbal. More specifically, the objective of the invention is to
limit the rotational or twisting motion of the suspension as well
as the up-down motion of the suspension or gimbal relative to the
disc surface.
[0014] These and other objectives of the invention are achieved by
providing a gimbal spring which flexibly supports the slider
relative to the disc surface. The design incorporates a base
mounting portion which connects the gimbal spring to a load beam
and thereby to the actuator of the disc drive which positions the
gimbal and slider over a desired track on the disc. The gimbal
includes opposed spaced flexure arms which are formed of elongated
members, each having a proximal end and a distal end which define
an opening therebetween, the proximal ends of the flexure arms
being operably coupled to the base portion, and the distal end
being cantilevered. A mounting tab is positioned between the ends
of the flexure arms and supports the slider. Bridge sections are
provided which connect the distal ends of the flexure arms to the
mounting tab, the bridge sections extending at an angle relative to
the flexure arms and being angled back toward the base section of
the gimbal. More specifically, the bridges are curved to conform to
the curvature of an optical lens mounted on the slider to be used
to read information from or store information on the surface of the
disc.
[0015] In a further feature, a deflection limiter is provided by
defining a limiter comprising a continuous member extending across
the width of the load beam tongue. The limiter extends over one
surface of the load beam tongue; the opposite surface of the load
beam tongue supports the slider. Preferably, the limiter extends
from one section to the other so that the load beam is captured,
and its vertical movement restrained, between sections and the
limiter.
[0016] Another unique feature of this design approach is that it
places the limiter and bond tongue towards the leading edge of the
slider. This is beneficial for a ramp load/unload device since it
will tend to lift the slider by the leading edge and prevent the
leading edge of the slider from crashing into the disc as other
gimbal/limiter concepts do that constrain motion at the trailing
edge of the gimbal.
[0017] Other features and advantages of the invention can be found
by reference to the attached drawings and accompanying description
of an exemplary embodiment
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a schematic illustration of operation of an
optical disc drive system.
[0019] FIG. 2 is a side view of a slider supporting an SIL.
[0020] FIG. 3 is a top view of a suspension assembly coupled to an
actuator mechanism for supporting a slider relative to a disc
surface (not shown).
[0021] FIG. 4 is a cross-sectional view taken along line 4-4 of
FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] FIG. 1 is a simplified diagram illustrating an optical
storage system using a solid immersion lens (SIL). Obviously, the
invention can be used with many other slider designs and associated
lenses. Optical system 10 includes an optical disc 12 having a data
surface which carries optically encoded information. Disc 12
rotates about spindle 14 and is driven by a spindle motor 16
mounted on base 18. A slider 20 is movably supported relative to
disc surface 12 via an actuator mechanism 22.
[0023] The slider 20 supports an SIL 24 for focusing a laser beam
of an optical system on the disc surface for reading
optically-encoded information. The actuator mechanism 22 preferably
includes a voice coil motor 26. The slider 20 is coupled to the
voice coil motor via a suspension assembly 28. The optical system
includes an optical head 30 which preferably is coupled to the
actuator mechanism 22 and operated thereby. The optical head 30
includes a laser beam which is focused onto the disc surface via
the SIL 24 in a known manner for operation of the optical disc
drive system.
[0024] FIG. 2 illustrates the slider 20 and SIL 24 construction.
Preferably, the slider is formed of a transparent material, such as
a cubic zirconia. The SIL 24 is bonded to the slider 20 or,
alternatively, the slider 20 and SIL 24 may be formed of an
integral material machined from a single piece of crystal. For
example, the integrated SIL 24 and slider 20 can be formed by
injection molding a single piece of transparent material such as a
commercially available polycarbonate in a known manner. The slider
20 includes an upper surface 32 and a lower air bearing surface
(ABS) 34 (surface not visible in FIG. 2) which is formed in a known
manner to provide a hydrodynamic lifting force to the slider 20 and
the lens 24 via rotation of optical disc 12 in a known manner.
[0025] The slider 20 is supported by a suspension assembly 28
operably coupled to the actuator mechanism. In particular, as
illustrated in FIG. 3, the suspension assembly 28 includes a load
beam 36 and a gimbal spring 40. Preferably, the load beam 36 is
formed of an elongated flexible material which includes side rails
44 and a load tab 46 having load button 48 (on a lower surface of
load tab 46) at an extended end of the load beam 36 as will be
explained. Side rails 44 provide lateral and bending stiffness and
a means for connecting wires (not shown) to the slider 20.
[0026] The gimbal spring 40 is coupled to the load beam 36 and
flexibly supports slider 20 relative to the load beam 36. The load
button 48 applies a load force to the upper surface 32 of the
slider and defines a gimbal pivot axis 50 about which the slider 20
can pitch, and pivot axis 68 about which the slider 20 can roll,
relative to the disc surface for operation of the disc drive.
[0027] The lower air bearing surface 34 of the slider 20 (not
shown) faces the disc surface so that rotation of disc 12 provides
a hydrodynamic lifting force to the slider 20 which flies above the
disc surface as data is read and written to the disc surface. The
load force counteracts the hydrodynamic lifting force of the
ABS.
[0028] The slider is lifted via the ABS surface to fly at a pitch
angle relative to the disc surface. During operation of the disc
drive, it is important to maintain a stable fly height for slider
20 close to the disc surface and that the slider 20 be able to
pitch and roll to follow the topography of the disc surface. Thus,
the gimbal spring 40 should be designed to support the slider
relative to the load beam to allow sufficient pitch and roll of the
slider 20 during operation. If the pitch and roll stiffness of the
gimbal spring is too low, it will be difficult to control the fly
characteristics of the slider and the gimbal will exhibit
undesirable resonance behavior. If the gimbal spring 40 is too
stiff in the pitch and roll axes, then the slider will not be able
to follow the topography of the disc surface.
[0029] During operation, the actuator mechanism 22 moves the
suspension assembly to position the slider 20 and SIL 24 relative
to selected positions on the disc surface. Rotation of the disc
supplies a lifting force to the slider 20 at the ABS surface.
Operation of the slider thus introduces vibration to the suspension
system which, depending on the construction of the suspension
assembly and gimbal spring 40, may coincide with the resonance
frequencies of the suspension system, causing the external motion
to be amplified. Vibration of the suspension system at the
resonance frequencies may interfere with placement and operation of
the slider 20. Typical excitation forces are fairly low-frequency,
less than 10,000 Hz. Thus, it is desirable to design the gimbal
spring so that its resonance frequencies are high to avoid
resonance vibration at typical operation frequencies of the disc
drive.
[0030] Further, as discussed, during operation of an optical disc
drive, a slider 20 supports an SIL 24 above the disc surface via
operation of the ABS surface and the load force of the load beam
36. Depending upon the position of the load button 48 and gimbal
pivot 50, the weight of the SIL 24 may be unbalanced relative to
the load position and during operation may excite the gimbal spring
40. Depending upon the design of the suspension system, this
vibration is amplified at the resonance frequency, thus degrading
the performance of the slider and SIL 24. The gimbal spring 40 of
the present invention is designed to provide desirable pitch and
roll stiffness with desired resonance frequency as will be
explained.
[0031] Further, during a shock event the mass of the head and lens
can pull the gimbal away from the load beam in the absence of some
deflection limiting mechanism. This deflection will induce stress
in the gimbal. The stress could be high enough to yield the gimbal
and result in dimple separation and changes to the pitch and roll
static angle of the gimbal. A deflection limiter will prevent this
from happening by ensuring that the deflection is not large enough
to cause the stress to reach the yield point.
[0032] As shown in FIG. 3, the slider includes a leading edge 52
and a trailing edge 54, and the distance between the leading edge
and trailing edge defines the longitudinal extent of the slider.
The SIL 24 is positioned toward the trailing edge 54 of the slider
20 on a rear portion of the slider 20. Since the SIL 24 is
positioned along the rear portion, the distribution of weight
between forward portion and rear portion is unbalanced. The load
tab 46 extends from the leading edge 52 over a forward portion 58
of the slider. The load tab 46 is sized to extend over the forward
portion 58 to a center portion of the slider so that the pivot axis
50 is generally at the center portion of the slider 20 for flight
stability of the slider 20 during operation.
[0033] The suspension assembly illustrated in FIG. 3 illustrates an
embodiment of a gimbal spring 40 of the present invention for
supporting slider 20 designed to optimize pitch and roll stiffness
and gimbal resonance characteristics while incorporating deflection
limiting capability. As shown, the gimbal spring 40 generally
includes spaced flexure arms 62, 64 and a slider mounting tab 66.
The gimbal spring 40 is cantileveredly supported relative to the
load beam 36 via a mounting portion (not shown but well known in
the industry). Spaced flexure arms 62, 64 are supported by and
extend from the mounting portion in spaced cantilevered relation.
Slider mounting tab 66 is operably coupled to the flexure arms 62,
64 and is fixedly secured to the slider 20 to flexibly support the
slider 20 relative to the load beam 36 to gimbal (pitch and roll)
relative to pivot axis 50 and 68.
[0034] The flexure arms 62, 64 are spaced relative to the width of
the slider 20 a certain distance from the centerline 68, and width
70 of each of the flexure arms 62, 64 is sized to provide desired
roll characteristics. If the flexure arms 62, 64 are spaced too far
apart, roll stiffness increases and if spaced too close, roll
stiffness is too low. If the width 70 of the flexure arms 62, 64 is
too thick, roll stiffness increases and if too thin, roll stiffness
is too low. Flexure arms 62, 64 include a proximal end 72 and a
distal end 74. The proximal end 72 is coupled to the mounting
portion and distal end 74 is coupled to mounting tab 66. The
proximal end 72 is fixed relative to the load beam 36 and the
distal end 74 flexibly supports slider 20 relative to the pivot
axis 50. As shown, the distal end 74 is cantilevered beyond the
pivot axis 50 of slider 20 to provide desired pitch stiffness
relative to load button 48 at pivot axis 50. The extent or length
of the flexure arms 62, 64 tends to decrease the pitch stiffness
based upon the width and thickness of the flexure arms 62, 64. The
extent between the proximal and distal ends 72, 74 is sufficient so
that when mounting tab 66 is coupled to the upper surface of the
slider 20 and load button 48 is aligned generally at the center
portion 59 of the slider 20, a portion of the flexure arms extends
beyond pivot axis 50 to provide sufficient pitch stiffness for
desired fly characteristics.
[0035] As shown, the length of the flexure arms 62, 64 is designed
so that when the mounting tab 60 is secured to the load beam 36 and
load beam 36 is positioned so that the load button supplies a load
force to the center portion 59 of the slider, the distal end 74
extends beyond the pivot axis 50 but does not extend along the
entire rear portion 56 to the trailing edge of the slider 20. The
shortened length provides increased gimbal resonance frequencies
for bending or torsion of the gimbal as compared to flexure arms
having a greater flexure length for movably supporting the slider
relative to the pivot axis 50. The design also provides a reduced
width and offset flexure arms 62, 64 having lower roll
stiffness.
[0036] As shown, mounting tab 66 couples the distal end 74 of
flexure arms 62, 64 to slider 20. For an optimal disc drive system,
placement of mounting tab 66 is restricted by the SIL 24. In the
embodiment shown, the SIL 24 is supported in the rear portion 56,
thus interferes with placement of mounting tab 66 in alignment with
the distal end 74 of flexure arms 62, 64.
[0037] Thus as shown, the distal ends 74 of flexure arms 62, 64 are
coupled to a proximally spaced mounting tab 66 via bridges 76, 78.
Bridges 76, 78 extend at a sloped angle to connect distal ends 74
of flexure arms 62, 64 to the proximally spaced mounting tab 66.
The sloped design of bridges 76, 78 provides a direct connection
between distal end 74 of flexure arms 62, 64 and mounting tab 66
which does not require additional width between arms 62, 64. The
angled relation between distal end 74 and bridges 76, 78 defines a
gap 82 between flexure arms 62, 64 and bridges 76, 78 for desired
flexure of the gimbal spring. Sides 83, 84 of bridges 76, 78 are
preferably curved to the contour of the SIL for placement close to
the SIL and a side 86 of the mounting tab 66 is also curved to the
contour of the SIL. The length of the flexure arms from axis 50 to
distal end 74 is important in providing a pitch stiffness low
enough to allow proper flying characteristics. The curved shape of
the flexure mounting tabs or bridges 76, 78 allows this increased
length. This design also keeps the dimple in the midsection of the
arms.
[0038] Thus, as described, the gimbal spring 40 of the present
invention is not limited to the shape of the particular mounting
tab 66 shown; alternately designed mounting tabs 66 may be designed
to secure the flexure arms 62, 64 relative to the slider 20. If
there is not sufficient area, SIL 24 will restrict placement of the
load button 42 toward the center of slider 20. Preferably, the load
button 48 is formed by an etching process. The load button or
dimple 48 formed by the etching process requires less surface area
to form the dimple than traditionally formed dimples. Thus, the
load button 48 formed by the etching process limits the contact to
the slider 20 and provides sufficient surface area to mount the
mounting tab 66 and wire termination pads relative to the upper
surface 31 of the slider 20.
[0039] Thus, as described, the bridge design of the present
invention illustrates the shape of a preferred embodiment of the
gimbal spring 40 of the present invention.
[0040] In summary, in addition to significantly lower roll
stiffness, the new gimbal design also greatly increases the
resonance frequencies of the gimbal resonance modes. The reduced
roll stiffness is further aided by reducing the thickness of the
gimbal from 0.0015" to 0.001" and reducing the width of the arms
62, 64. However, if these were the only changes, the gimbal would
probably have unacceptably low gimbal resonance frequencies. To
overcome this problem, the bond or slider mounting pad 66 was moved
from the trailing edge of the lens 24 to the leading edge. This
reduced the length of the gimbal arms 62, 64 and greatly increased
the resonance frequencies of the gimbal modes.
[0041] If the gimbal arms 62, 64 are shortened too much, the entire
length of the gimbal arms would be on the leading edge side of the
load point. It is highly desirable for pitch stiffness to have some
length of the gimbal arms on both sides of the load point. To
accomplish that with this design, a unique feature was
incorporated. The unique feature is the circular shape or edge to
the bond pad. The circular shape follows the profile of the
objective lens 24 and allows the gimbal arms 62, 64 to be extended
past the load point towards the trailing edge of the slider. In
FIG. 3, if the straight lead edge 69 of the bond pad 66 were
extended straight out until it intersected the gimbal arms 62, 64
the region 73 would be filled in and solid. As a result, the pitch
stiffness would be approximately 50% higher.
[0042] This design is also especially adaptable to incorporate a
deflection limiter. The deflection limiter in this application
comprises a continuous member 90 supported from the slider mounting
pad 66 and extending across the width of the low beam tongue 46.
The limiter extends across the opposite surface of the tongue which
contacts the dimple 48. This makes the limiter 90 which is
supported from the bonding pad 66 very strong and able to resist
great forces without bending or otherwise allowing the limiter to
become disengaged and maintains the load tab 46 in contact with the
load button 48. Another benefit of the design is that the limiter
is very strong and able to resist great forces without bending or
otherwise allowing the limiter 90 to become disengaged and allowing
the slider to deflect without restriction.
[0043] A further feature of this design approach is that it places
the limiter 90 and the bond tongue 46 toward the leading edge of
the slider. This is very beneficial for a ramp load/unload device
since it will tend to lift the slider by the leading edge and
prevent the leading edge of the slider from crashing into the disc
as other gimbal/limiter concepts may do, which constrain motion of
the trailage edge of the gimbal. The construction of the present
invention is further shown in FIG. 4 at the left-hand side the load
beam 36 is shown with upraised tabs 92, 94 which are used to hold
the electrical connectors in the load beam as they extend out to
the transducer (not shown) supported on the slider. The figure also
shows the slider 20 supporting the lens 24, with movement of the
slider relative to the mounting tab 66 being freely available over
contact 66 and the dimple 48. The limiter is formed by providing a
substantially vertical connecting portion 92 between the rear of
the mounting tab 66 and the limiter 90 so that the limiter 90 is
substantially parallel in a parallel plane but in a different
elevation. The low beam 46 can be extended through an opening 95
(FIG. 3) between mounting tab 66 and limiter 90, encaptured between
these two sections to restrain vertical movement of the load beam
46 relative to the slider, so that the slider cannot easily
separate itself from the load beam.
[0044] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
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