U.S. patent application number 14/949764 was filed with the patent office on 2016-03-17 for head gimbal assembly and storage device provided with the same.
The applicant listed for this patent is KABUSHIKI KAISHA TOSHIBA. Invention is credited to Masaya KUDO.
Application Number | 20160078890 14/949764 |
Document ID | / |
Family ID | 53173052 |
Filed Date | 2016-03-17 |
United States Patent
Application |
20160078890 |
Kind Code |
A1 |
KUDO; Masaya |
March 17, 2016 |
HEAD GIMBAL ASSEMBLY AND STORAGE DEVICE PROVIDED WITH THE SAME
Abstract
A head gimbal assembly includes a load beam, a wiring member
including a metal plate disposed on the load beam, a magnetic head
attached to a tip section of the wiring member, and a piezoelectric
element that is fixed to and supported by supporting pads and
deforms in response to a voltage applied thereto. The metal plate
includes a tip section to which the magnetic head is fixed, and a
base section that is spaced apart from the tip section and is fixed
to the load beam. The supporting pads include first and second
supporting pads proximate to the tip section and distal from the
base section and a third supporting pad proximate to the base
section and distal to the tip section, each of supporting pads
separated from and independent of both the tip section and the base
section.
Inventors: |
KUDO; Masaya; (Yokohama
Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOSHIBA |
Tokyo |
|
JP |
|
|
Family ID: |
53173052 |
Appl. No.: |
14/949764 |
Filed: |
November 23, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14190740 |
Feb 26, 2014 |
9196276 |
|
|
14949764 |
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Current U.S.
Class: |
360/99.08 ;
360/244.2 |
Current CPC
Class: |
B23K 26/364 20151001;
G11B 5/5552 20130101; G11B 5/4826 20130101; G11B 5/483 20150901;
G11B 5/4853 20130101 |
International
Class: |
G11B 5/48 20060101
G11B005/48 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 15, 2013 |
JP |
2013-236673 |
Claims
1. A head gimbal assembly comprising: a load beam; a wiring member
including a metal plate and an insulating layer disposed on the
metal plate and the load beam, the metal plate including a tip
section that is movable away from the load beam and a base section
that is fixed to the load beam; a magnetic head electrically
connected to a first wiring of the wiring member and attached to a
tip section of the wiring member; and an expanding and contracting
element that is fixed to supporting pads through the insulating
layer and configured to deform in response to a voltage applied
thereto through a second wiring of the wiring member, the
supporting pads including first and second supporting pads
proximate to the tip section of the metal plate and distal from the
base section and third and fourth supporting pads proximate to the
base section and distal from the tip section of the metal plate,
the first and second supporting pads being structurally separated
from and independent of both the tip section of the metal plate and
the base section, and the third and fourth supporting pads being
structurally connected to the base section.
2. The head gimbal assembly of claim 1, wherein the expanding and
contracting element includes a first element fixed to the first and
third supporting pads and a second element fixed to the second and
fourth supporting pads.
3. The head gimbal assembly of claim 1, wherein the third and
fourth supporting pads are structurally connected to the base
section by respective bridge sections, each having a width that is
substantially smaller than a width of the respective third and
fourth supporting pads.
4. The head gimbal assembly of claim 1, wherein the expanding and
contracting element includes first and second strips each having a
longitudinal axis aligned parallel to and on either side of a
longitudinal axis of the metal plate.
5. The head gimbal assembly of claim 4, wherein the first and
second strips deform in response to the voltage applied thereto to
rotate the magnetic head about an axis that is perpendicular to a
plane of the metal plate.
6. A storage device comprising: a disk-shaped recording medium; a
driving motor that supports and rotates the recording medium; and a
head gimbal assembly including: a load beam, a wiring member
including a metal plate and an insulating layer disposed on the
metal plate and the load beam, the metal plate including a tip
section that is movable away from the load beam and a base section
that is fixed to the load beam, a magnetic head electrically
connected to a first wiring of the wiring member and attached to a
tip section of the wiring member, and an expanding and contracting
element that is fixed to supporting pads through the insulating
layer and configured to deform in response to a voltage applied
thereto through a second wiring of the wiring member, the
supporting pads including first and second supporting pads
proximate to the tip section of the metal plate and distal from the
base section and third and fourth supporting pads proximate to the
base section and distal from the tip section of the metal plate,
the first and second supporting pads being structurally separated
from and independent of both the tip section of the metal plate and
the base section, and the third and fourth supporting pads being
structurally connected to the base section.
7. The device of claim 6, wherein the expanding and contracting
element includes a first element fixed to the first and third
supporting pads and a second element fixed to the second and fourth
supporting pads.
8. The device of claim 6, wherein the third and fourth supporting
pads are structurally connected to the base section by respective
bridge sections, each having a width that is substantially smaller
than a width of the respective third and fourth supporting
pads.
9. The device of claim 6, wherein the expanding and contracting
element includes first and second strips each having a longitudinal
axis aligned parallel to and on either side of a longitudinal axis
of the metal plate.
10. The device of claim 9, wherein the first and second strips
deform in response to the voltage applied thereto to rotate the
magnetic head about an axis that is perpendicular to a plane of the
metal plate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of co-pending
U.S. application Ser. No. 14/190,740, which was filed on Feb. 26,
2014, and which is based upon and claims the benefit of priority
from Japanese Patent Application No. 2013-236673, filed Nov. 15,
2013, the entire contents of which are incorporated herein by
reference.
FIELD
[0002] Embodiments described herein relate generally to ahead
gimbal assembly used in a storage device and a disk unit provided
with the same.
BACKGROUND
[0003] In recent years, disk drives such as a magnetic disk drives
and an optical disk drives are widely used as an external recording
device and an image recording device of a computer.
[0004] The magnetic disk drive generally includes a magnetic disk
placed in a case, a spindle motor that supports and rotates the
magnetic disk, and a head gimbal assembly (HGA). The head gimbal
assembly includes a suspension that is attached to a tip section of
an arm, a flexure (a wiring member) that is provided on the
suspension and is connected to the outside, and a magnetic head
that is supported on the suspension with a gimbal section of the
flexure. A wiring of the flexure is electrically connected to the
magnetic head. Moreover, the suspension includes a load beam and a
base plate fixed to a base end side of the load beam, and the base
plate is fixed to the tip section of the arm.
[0005] In recent years, an HGA in which a thin-film piezoelectric
element (PZT element) is mounted on a gimbal section of a flexure
and a microscopic displacement is caused in a seek direction of a
magnetic head by an expansion and contraction of the piezoelectric
element, has been proposed. With this HGA, the operation of the
magnetic head may be controlled by varying a voltage applied to the
piezoelectric element.
[0006] However, in the above-described HGA, when the piezoelectric
element expands or contracts by a voltage application, the
piezoelectric element bends in a thickness direction thereof and an
out-of-plane vibration is sometimes generated. The out-of-plane
vibration is transferred to a load beam via the flexure,
unnecessarily exciting the resonance frequency of the load beam. As
a result, the positioning accuracy of the magnetic head is
reduced.
DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a perspective view showing a hard disk drive (HDD)
according to a first embodiment.
[0008] FIG. 2 is a perspective view showing a head gimbal assembly
of the HDD.
[0009] FIG. 3 is a perspective view showing a tip section and a
gimbal section of the head gimbal assembly.
[0010] FIG. 4 is an exploded perspective view showing a magnetic
head, piezoelectric elements, a flexure (a wiring member) , and a
load beam of the head gimbal assembly.
[0011] FIG. 5 is a sectional view of the tip section of the head
gimbal assembly taken on the line A-A of FIG. 3.
[0012] FIG. 6 is a sectional view of the head gimbal assembly
corresponding to FIG. 5 in a state in which the piezoelectric
element expands.
[0013] FIG. 7 is a plan view schematically showing a drive state of
the magnetic head by the piezoelectric elements.
[0014] FIG. 8 is an exploded perspective view showing a magnetic
head, piezoelectric elements, a flexure, and a load beam of a head
gimbal assembly according to a second embodiment.
[0015] FIG. 9 is an exploded perspective view showing a magnetic
head, piezoelectric elements, a flexure, and a load beam of a head
gimbal assembly according to a third embodiment.
[0016] FIG. 10 is a diagram showing a comparison among the
vibrations generated in the cross-track direction in a light gap
position of the magnetic head in the head gimbal assemblies
according to the first to third embodiments and a head gimbal
assembly according to a comparative example.
DETAILED DESCRIPTION
[0017] An exemplary embodiment provides a head gimbal assembly and
a disk unit that may suppress the vibration of a load beam.
[0018] In general, according to one embodiment, a head gimbal
assembly includes a load beam, a wiring member including a metal
plate disposed on the load beam, an insulating layer disposed on
the metal plate and the load beam, and a conductive layer forming
first and second wirings, a magnetic head electrically connected to
the first wiring of the wiring member and attached to a tip section
of the metal plate, and a piezoelectric element that is fixed to
and supported by supporting pads and configured to deform in
response to a voltage applied thereto through the second wiring.
The metal plate includes a tip section to which the magnetic head
is fixed, and a base section that is spaced apart from the tip
section and is fixed to the load beam. The supporting pads include
first and second supporting pads proximate to the tip section and
distal from the base section and a third supporting pad proximate
to the base section and distal to the tip section, each of the
supporting pads separated from and independent of both the tip
section and the base section.
[0019] Hereinafter, with reference to the drawings, a hard disk
drive (HDD) will be described in detail as a magnetic disk unit
according to an embodiment.
First Embodiment
[0020] FIG. 1 shows an internal structure of the HDD from which a
top cover is removed. As shown in FIG. 1, the HDD includes a
housing 10. The housing 10 includes a base 12 in the shape of a
rectangular box, with an opening on a top face thereof, and a top
cover (not shown) that closes the top opening of the base 12 by
being secured to the base 12 with a plurality of screws. The base
12 includes a rectangular bottom wall 12a and a side wall 12b
erected along the outer edge of the bottom wall.
[0021] In the housing 10, two magnetic disks 16 are provided as
recording media and a spindle motor 18 is provided as a drive
section that supports and rotates the magnetic disks. The spindle
motor 18 is provided on the bottom wall 12a. Each magnetic disk 16
is formed to have a diameter of 2.5 inches (6.35 cm), for example,
and includes a magnetic recording layer on a top face and a lower
face. The magnetic disks 16 are concentrically fitted onto a hub
(not shown) of the spindle motor 18 and are clamped by a clamp
spring 27 and thereby fixed to the hub. As a result, the magnetic
disks 16 are supported in a state in which the magnetic disks 16
are parallel to the bottom wall 12a of the base 12. The magnetic
disks 16 are rotated by the spindle motor 18 at a predetermined
speed.
[0022] In the housing 10, a plurality of magnetic heads 17 that
record and reproduce information on and from the magnetic disks 16
and a head stack assembly (hereinafter referred to as an HSA) 22
that movably supports the magnetic heads 17 with respect to the
magnetic disks 16 are provided. Moreover, in the housing 10, a
voice coil motor (hereinafter referred to as a VCM) 24 that
rotationally moves and positions the HSA 22, a ramp loading
mechanism 25 that holds the magnetic heads in an unloading position
which is away from the magnetic disks when the magnetic heads 17
move to the outermost periphery of the magnetic disks 16, a latch
mechanism 26 that holds the HSA in a retraction position when an
impact or the like is given to the HDD, and a substrate unit 21
including a connector and so forth, are provided.
[0023] On the outer surface of the bottom wall 12a of the base 12,
a printed circuit board (not shown) is secured with screws. The
printed circuit board controls the operations of the spindle motor
18, the VCM 24, and the magnetic heads 17 via the substrate unit
21. Near the side wall 12b of the base 12, a circulating filter 23
that captures dust generated in the housing due to the operation of
the movable section is provided and is located on the outside of
the magnetic disks 16. Moreover, near the side wall 12b of the base
12, a breathing filter 15 that captures dust from the air flowing
into the housing 10 is provided.
[0024] As shown in FIG. 1, the HSA 22 includes a rotatable bearing
unit 28, four arms 32 that are attached to the bearing unit in a
stacked configuration, a head gimbal assembly (hereinafter referred
to as an HGA) 30 extending from each arm 32, and spacer rings (not
shown) disposed in such a way as to be stacked between the arms 32.
Each arm 32 is formed to have a long flat plate-like shape from
stainless steel, aluminum, or the like, for example. Each arm 32
includes a tip section on the side where an extension end is
located, and, in this tip section, a caulking bearing surface
provided with a caulking hole (not shown) is formed. The bearing
unit 28 includes a pivot erected in the bottom wall 12a of the base
12 near the outer periphery of the magnetic disks 16 and a
cylindrical sleeve rotatably supported on the pivot with a bearing
placed between the cylindrical sleeve and the pivot.
[0025] FIG. 2 is a perspective view showing the HGA 30. As shown in
FIGS. 1 and 2, each HGA 30 includes a suspension 34 extending from
the arm 32 and a magnetic head 17 supported on the extension end of
the suspension 34.
[0026] The suspension 34 includes a rectangular base plate 42 made
of a metal plate which is several hundreds of micrometers in
thickness and a load beam 35 in the shape of a long leaf spring,
the load beam 35 being made of a metal plate which is several tens
of micrometers in thickness. A base end of the load beam 35 is
disposed in such a way as to be stacked on a tip section of the
base plate 42 and is fixed to the base plate 42 by performing
welding in multiple places. The width of the base end of the load
beam 35 is formed to be substantially equal to the width of the
base plate 42. At the tip of the load beam 35, a long rod-like tab
46 is provided in such a way as to protrude therefrom.
[0027] The base plate 42 is provided with a circular opening and a
ring-shaped protrusion 43 located around this opening in a base end
thereof. The base plate 42 is secured to the tip section of the arm
32 as a result of the protrusion 43 being fitted into the circular
caulking hole (not shown) formed in the caulking bearing surface of
the arm 32 and the protrusion 43 being crimped.
[0028] The HGA 30 includes a pair of piezoelectric elements (PZT
elements) 50 and a long strip-shaped flexure (wiring member) 40 for
transmitting a recording and reproduction signal and a drive signal
of the piezoelectric element. As shown in FIG. 2, a tip-side
portion 40a of the flexure 40 is mounted on the load beam 35 and
the base plate 42, and a rear portion (an extending section) 40b
extends from a side edge of the base plate 42 to the outside and
extends along a side edge of the arm 32. In addition, a connection
end of the flexure 40 located at the tip of the extending section
40b is connected to a main FPC 21b which will be described
later.
[0029] A tip section of the flexure 40 located on a tip section of
the load beam 35 forms a gimbal section 36, and the magnetic head
17 and the piezoelectric elements 50 are mounted on the gimbal
section 36. The magnetic head 17 includes a slider having a
virtually prismatic shape and a recording element and a
reproduction element which are provided in the slider, and is fixed
on the gimbal section 36 and is supported on the load beam 35 with
the gimbal section 36 placed between the magnetic head 17 and the
load beam 35. A pair of the piezoelectric elements (PZT elements)
50 is attached to the gimbal section 36 and is located, near the
magnetic head 17, on the side of the load beam 35 where the base
end thereof is located.
[0030] FIG. 3 is a perspective view showing an enlarged magnetic
head portion of the HGA 30, FIG. 4 is an exploded perspective view
showing the magnetic head, the piezoelectric elements, the flexure,
and the load beam of the HGA, and FIG. 5 is a sectional view of the
HGA, showing a portion in which the piezoelectric element is
mounted.
[0031] As shown in FIGS. 2 to 5, the flexure 40 includes a metal
thin plate (a backing layer) 44a made of stainless steel or the
like, the metal thin plate (the backing layer) 44a serving as a
base, an insulating layer 44b formed on the metal thin plate, a
conductive layer (a wiring pattern) 44c that is formed on the
insulating layer 44b and forms a plurality of wiring 45a, and a
protective insulating layer (not shown) covering the conductive
layer 44c, and is formed as a long, strip-shaped laminated plate.
The side of the tip-side portion 40a of the flexure 40 where the
metal thin plate 44a is located is pasted or spot-welded to the
surfaces of the load beam 35 and the base plate 42.
[0032] In the gimbal section 36 of the flexure 40, the metal thin
plate 44a includes a rectangular tongue section 36a located on the
tip side, a rectangular base end 36b located on the base end side
with a spacing (distance) between the tongue section 36a and the
base end 36b, and a pair of right and left link sections 36c
extending from the tongue section 36a to the base end 36b. In the
space between the tongue section 36a and the base end 36b, a pair
of island-shaped first supporting sections (supporting pads) 36d
and a pair of island-shaped second supporting sections (supporting
pads) 36e are provided. These first and second supporting sections
36d and 36e are formed of a metal thin plate.
[0033] The pair of first supporting sections 36d is located near
the tongue section 36a and is disposed side by side in the width
direction of the gimbal section 36. Moreover, the pair of second
supporting sections 36e is located near the base end 36b and is
disposed side by side in the width direction of the gimbal section
36. Between each second supporting section 36e and the base end
36b, a slit section or a notch section 38 is provided, and the
second supporting sections 36e and the base end 36b are separated
from each other. The first supporting sections 36d and the second
supporting sections 36e are arranged in the longitudinal direction
of the gimbal section 36 with a space section between the first
supporting sections 36d and the second supporting sections 36e.
[0034] In the gimbal section 36, the insulating layer 44b and the
conductive layer 44c extend to the tip side of the tongue section
36a passing over the base end 36b, passing through the slit section
or the notch section 38, passing over the pair of second supporting
sections 36e, passing through the space section, and passing over
the pair of first supporting sections 36d.
[0035] The magnetic head 17 is fixed to the tongue section 36a with
an adhesive and the insulating layer 44b is disposed between the
magnetic head 17 and the tongue section 36a. The base end 36b of
the metal thin plate 44a is fixed to the load beam 35 by welding or
the like. A portion of the tongue section 36a which is
substantially at the center thereof makes contact with a dimple (a
support protrusion) 48 provided in the tip section of the load beam
35 in such a way as to protrude therefrom. The tongue section 36a
and the magnetic head 17 may swing or roll about the dimple 48 by
elastic deformation of the link sections 36c.
[0036] The piezoelectric elements 50 are formed to have a long,
rectangular plate-like shape and expand and contract in the
longitudinal direction thereof. The piezoelectric elements 50 are
fixed to the insulating layer 44b of the gimbal section 36 with an
adhesive or the like. The piezoelectric elements 50 are disposed in
such a way that the longitudinal direction thereof is parallel to
the longitudinal direction of the load beam 35 and the flexure 40.
As a result, the two piezoelectric elements 50 are disposed in such
a way that the piezoelectric elements 50 are arranged parallel to
each other and a space is left therebetween in the width direction
of the gimbal section 36.
[0037] As shown in FIG. 5, one end of each piezoelectric element 50
in the longitudinal direction thereof, that is, an end of the
piezoelectric element 50 on the side where the magnetic head 17 is
located is supported on the first supporting section 36d. The other
end of each piezoelectric element 50 in the longitudinal direction
thereof, that is, an end of the piezoelectric element 50 on the
side where the base end 36b is located is supported on the second
supporting section 36e.
[0038] As shown in FIGS. 3 to 5, some of the wiring 45a of the
flexure 40 are wiring for transmitting a recording and reproduction
signal to the magnetic head 17, and these wiring extend to the
magnetic head 17 and include electrode pads 45b at the extension
ends thereof. These electrode pads 45b and the recording and
reproduction elements of the magnetic head 17 are electrically
joined to each other with solder or an electrically-conducting
adhesive such as a silver paste. Moreover, some of the wiring 45a
of the flexure 40 transmit a drive signal to the piezoelectric
elements 50, and these wiring extend to the vicinity of the
piezoelectric elements 50 and include electrode pads 45c at the
extension ends thereof. These electrode pads 45c and the
piezoelectric elements 50 are electrically joined to each other
with solder or an electrically-conducting adhesive such as a silver
paste. Incidentally, these wiring 45a extend to the connection end
side of the flexure along the flexure 40 and are connected to
connection pads (not shown) provided at the connection end.
[0039] Each piezoelectric element 50 expands and contracts in the
longitudinal direction of the flexure 40 by a voltage application
as indicated with arrows in FIGS. 6 and 7. By driving these two
piezoelectric elements 50 in such a way that the piezoelectric
elements 50 expand and contact in opposite directions, the tongue
section 36a of the gimbal section 36 may be swung via the flexure
40 and the magnetic head 17 may be displaced in a seek direction.
In this embodiment, since the space between the first supporting
section 36d and the second supporting section 36e that support the
piezoelectric elements 50 and the base end 36b of the metal thin
plate 44a is mainly maintained by the low rigidity of the
insulating layer 44b, the out-of-plane vibration during driving of
the piezoelectric elements is prevented from being transferred to
the load beam 35 via the base end 36b of the metal thin plate
44a.
[0040] As shown in FIG. 1, the HSA 22 includes a supporting frame
extending from the bearing unit 28 in a direction opposite to the
arm 32, and a voice coil forming part of the VCM 24 is embedded in
the supporting frame. When the HSA 22 configured as described above
is mounted on the base 12, a lower end of the pivot of the bearing
unit 28 is fixed to the base 12, and the bearing unit 28 is erected
in such a way as to be substantially parallel to the spindle of the
spindle motor 18. Each magnetic disk 16 is located between the two
HGAs 30. During operation of the HDD, the magnetic heads 17
attached to the suspensions 34 face the top face and the lower face
of each magnetic disk 16 and are located on the sides where the
faces of the magnetic disk 16 are located. The voice coil fixed to
the supporting frame is located between a pair of yokes 37 fixed on
the base 12, and these yokes and a magnet (not shown) fixed to one
yoke form the VCM 24.
[0041] As further shown in FIG. 1, the substrate unit 21 includes a
main body 21a formed of a flexible printed circuit board, and the
main body 21a is fixed to the bottom wall 12a of the base 12. On
the main body 21a, a connector and an electronic component for
connection with the printed circuit board (both not shown) are
mounted.
[0042] The substrate unit 21 includes a main flexible printed
circuit board (hereinafter referred to as a main FPC) 21b extending
from the main body 21a. An extension end of the main FPC 21b forms
a connection end and is fixed to the vicinity of the bearing unit
28 of the HSA 22. The flexure 40 of each HGA 30 is mechanically and
electrically connected to the connection end of the main FPC 21b.
As a result, the substrate unit 21 is electrically connected to the
magnetic head 17 and the piezoelectric elements 50 via the main FPC
21b and the flexure 40.
[0043] As shown in FIG. 1, the ramp loading mechanism 25 includes a
ramp 47 disposed outside the magnetic disks 16 on the bottom wall
12a of the base 12 and the tab 46 (see FIGS. 2 to 4) extending from
the tip of each suspension 34. When the HSA 22 rotationally moves
about the bearing unit 28 and the magnetic heads 17 move to the
retraction position located outside the magnetic disks 16, each tab
46 engages a ramp surface formed in the ramp 47 and is then pulled
up by the inclination of the ramp surface. As a result, the
magnetic heads 17 are unloaded from the magnetic disks 16 and are
held in the retraction position.
[0044] According to the HDD and the HGA 30 configured as described
above, the piezoelectric elements 50 are attached to the gimbal
section 36 of the flexure 40, and, by applying a voltage to the
piezoelectric elements 50 via the flexure 40, the magnetic head 17
attached to the gimbal section may be displaced in a seek
direction. As a result, by controlling the voltage applied to the
piezoelectric elements 50, the position of the magnetic head 17 may
be finely controlled and the positioning accuracy of the magnetic
head may be improved.
[0045] Moreover, in the gimbal section 36 to which the
piezoelectric elements 50 are attached, the first supporting
sections 36d and the second supporting sections 36e of the metal
thin plate 44a, the first supporting sections 36d and the second
supporting sections 36e supporting both ends of the piezoelectric
elements 50 in the longitudinal direction thereof, are separated
from and independent of the base end 36b of the metal thin plate
44a. The first supporting sections 36d and the second supporting
sections 36e and the base end 36b of the metal thin plate 44a are
connected to one another mainly by the insulating layer 44b having
low rigidity. Therefore, even when an out-of-plane vibration is
generated in the piezoelectric elements 50 and the first and second
supporting sections 36d and 36e during driving of the piezoelectric
elements 50, the out-of-plane vibration are prevented from being
transferred to the load beam 35 via the base end 36b of the metal
thin plate 44a. As a result, a head gimbal assembly that suppresses
unnecessary resonance excitation of the load beam 35 and improves
the positioning accuracy of the magnetic head 17 may be
obtained.
[0046] Next, HGAs according to other embodiments will be described.
In the other embodiments described below, portions that are
identical to those of the first embodiment described above are
identified with the same reference characters, and the detailed
descriptions thereof are omitted.
Second Embodiment
[0047] FIG. 8 is an exploded perspective view showing a magnetic
head 17, piezoelectric elements 50, a flexure 40, and a load beam
35 of an HGA 30 according to a second embodiment. According to this
embodiment, in a gimbal section 36, part of each of a pair of
second supporting sections 36e of a backing metal thin plate 44a is
connected to the base end 36b by a long bridge section 41 . The
width of the bridge section 41 is formed to be sufficiently smaller
than the width of the second supporting section 36e. Except for the
bridge section 41, each second supporting section 36e is separated
from the base end 36b by the notch section 38.
[0048] In the second embodiment, the other structures of the HGA 30
and the HDD are the same as the structures of the HGA 30 and the
HDD of the first embodiment described previously.
[0049] Also in the second embodiment structured as described above,
an out-of-plane vibration that is transferred from the second
supporting section 36e to the base end 36b of the metal thin plate
44a may be reduced and unnecessary resonance excitation of the load
beam may be suppressed. Moreover, since the bridge section 41 is
provided, the supporting stability of the piezoelectric elements 50
is improved. As a result, a head gimbal assembly that improves the
positioning accuracy of the magnetic head 17 may be obtained.
Third Embodiment
[0050] FIG. 9 is an exploded perspective view showing a magnetic
head 17, piezoelectric elements 50, a flexure 40, and a load beam
35 of an HGA 30 according to a third embodiment. According to this
embodiment, in a gimbal section 36, the second supporting section
36e of a backing metal thin plate 44a is formed as one common
second supporting section. The second supporting section 36e is
formed to have a rectangular shape and extends in the width
direction of the gimbal section 36. Moreover, the second supporting
section 36e is separated from a base end 36b by the slit section or
the notch section 38. The single second supporting section 36e
supports one end of each of the two piezoelectric elements 50.
[0051] In the third embodiment, the other structures of the HGA 30
and the HDD are the same as the structures of the HGA 30 and the
HDD of the first embodiment described previously.
[0052] Also in the third embodiment structured as described above,
an out-of-plane vibration that is transferred from the second
supporting section 36e to the base end 36b of the metal thin plate
44a may be reduced and unnecessary resonance excitation of the load
beam may be suppressed. As a result, a head gimbal assembly and the
HDD that improves the positioning accuracy of the magnetic head 17
may be obtained. In a modification of the third embodiment, the
second supporting section 36e may be connected to the base end 36b
by one or a plurality of bridge sections.
[0053] FIG. 10 shows the results of a simulation of frequency
transmission characteristics of cross-track direction displacement
at a write gap position (or read-write element position) of a
magnetic head for a drive voltage of the piezoelectric elements 50.
The simulation is performed using a finite-element analysis on the
HGAs according to the first to third embodiments described above
and a comparative example. Moreover, in FIG. 10, the frequency
transmission characteristics in the 7 kHz band which is a primary
torsional resonance frequency of the load beam are shown. In an HGA
according to the comparative example, a second supporting section
is integrally formed in abase end of a metal thin plate.
[0054] The load beam 35 used in the simulation is a stainless plate
which is 30 .mu.m in thickness. In the flexure 40, the backing
metal thin plate is a stainless plate which is 18 .mu.m in
thickness, the insulating layer 44b is 8 .mu.m in thickness, and
the conductive layer 44c is 12 .mu.m in thickness. The thickness of
each piezoelectric element 50 is 10 .mu.m. Moreover, the conditions
of a voltage application to the piezoelectric elements 50 are the
same.
[0055] It is found from FIG. 10 that, under the same condition of a
voltage application, the primary torsional resonance gains of the
load beams in the first to third embodiments are smaller than the
primary torsional resonance gain of the load beam in the
comparative example. Therefore, in simulations, the first to third
embodiments described above are shown to prevent the out-of-plane
vibration of the piezoelectric elements 50 that is generated during
driving when the torsional resonance of the load beam is
unnecessarily excited and thereby enhance the positioning
performance of the suspension and the magnetic head.
[0056] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
inventions.
[0057] In the embodiments described above, as the arms of the HSA,
plate-like arms which are independent of one another are used, but
the arms are not limited to such arms; a structural member into
which a plurality of so-called E-block-shaped arms and a bearing
sleeve are integrated together may be applied. The magnetic disk is
not limited to a 2.5-inch magnetic disk, and a magnetic disk of
other size may be used. The number of magnetic disks is not limited
to two, and one or three or more magnetic disks may be used. The
number of HGAs may also be increased or reduced in accordance with
the number of placed magnetic disks.
* * * * *