U.S. patent application number 11/082800 was filed with the patent office on 2005-09-29 for magnetostrictive actuator.
This patent application is currently assigned to Sony Corporation. Invention is credited to Ohashi, Yoshio.
Application Number | 20050212364 11/082800 |
Document ID | / |
Family ID | 34980817 |
Filed Date | 2005-09-29 |
United States Patent
Application |
20050212364 |
Kind Code |
A1 |
Ohashi, Yoshio |
September 29, 2005 |
Magnetostrictive actuator
Abstract
A magnetostrictive actuator has magnetostrictive element having
a magnetostrictive, a driving rod moving in a displacement
direction of the magnetostrictive element, which is connected with
the magnetostrictive element and made of a ferromagnet, a solenoid
coil applying magnetic field to the magnetostrictive element, which
is arranged around the magnetostrictive element, an enclosure
enclosing the magnetostrictive element and the solenoid coil. In
the enclosure, a permanent magnet for applying static magnetic bias
field to the magnetostrictive element and tubular cases including a
ferromagnet are arranged around the enclosed magnetostrictive
element, and the driving rod is arranged in the enclosure with a
space. Magnetic pull-in force caused between the driving rod and
the enclosure can apply prestress to the magnetostrictive
element.
Inventors: |
Ohashi, Yoshio; (Kanagawa,
JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Sony Corporation
Tokyo
JP
|
Family ID: |
34980817 |
Appl. No.: |
11/082800 |
Filed: |
March 18, 2005 |
Current U.S.
Class: |
310/26 |
Current CPC
Class: |
H01L 41/12 20130101 |
Class at
Publication: |
310/026 |
International
Class: |
H02N 002/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 2004 |
JP |
2004-080967 |
Claims
What is claimed is:
1. A magnetostrictive actuator comprising: displacement-generating
means configured to generate a displacement caused by magnetic
material having a magnetostrictive; movable means configured to
move in a displacement direction of the displacement-generating
means, said movable means being connected with the
displacement-generating means and made of a ferromagnet;
magnetic-field-generating means configured to apply magnetic field
to the displacement-generating means, said
magnetic-field-generatin- g means being arranged around the
displacement-generating means; and enclosing device configured to
enclose the displacement-generating means and the movable means,
wherein in the enclosing means, magnetic-circuit-forming member
including a ferromagnet and a permanent magnet for applying static
magnetic bias field to the displacement-generating means are
arranged around the enclosed displacement-generating means; and
wherein the movable means is arranged in the enclosing means with a
space, thereby allowing magnetic pull-in force caused between the
movable means and the enclosing means to apply prestress to the
displacement-generating means.
2. The magnetostrictive actuator according to claim 1, wherein
sealing member having flexibility seals the space between the
movable means and the enclosing means.
3. The magnetostrictive actuator according to claim 1, wherein in
the enclosing means, a plurality of permanent magnets are arranged
in a displacement direction of the displacement-generating means
with an interval therebetween.
4. A magnetostrictive actuator comprising: displacement-generating
device configured to generate a displacement caused by magnetic
material having a magnetostrictive; movable member configured to
move in a displacement direction of the displacement-generating
device, said movable member being connected with the
displacement-generating device and made of a ferromagnet;
magnetic-field-generating device configured to apply magnetic field
to the displacement-generating device, said
magnetic-field-generating device being arranged around the
displacement-generating device; and enclosing device configured to
enclose the displacement-generating device and the movable member,
wherein in the enclosing device, magnetic-circuit-forming member
including a ferromagnet and a permanent magnet for applying static
magnetic bias field to the displacement-generating device are
arranged around the enclosed displacement-generating device; and
wherein the movable member is arranged in the enclosing device with
a space, thereby allowing magnetic pull-in force caused between the
movable member and the enclosing device to apply prestress to the
displacement-generating device.
Description
CROSSREFERENCE TO RELATED APPLICATION
[0001] The present invention contains subject matter related to
Japanese Patent Application JP 2004-080967 filed in the Japanese
Patent Office on Mar. 19, 2004, the entire contents of which being
incorporated herein by reference.
[0002] 1. Field of the Invention
[0003] The present invention relates to a magnetostrictive
actuator. More particularly, it relates to a magnetostrictive
actuator for generating displacement or vibration by utilizing a
magnetostrictive event.
[0004] 2. Background
[0005] As an actuator for generating displacement or vibration, a
piezoelectric actuator for generating displacement by applying
control voltage to a displacement-generation element using
piezoelectric material has been known. A magnetostrictive actuator
for generating displacement by applying magnetic field to a
displacement-generation element (referred to as "magnetostrictive
element" hereinafter) using magnetostrictive material has been also
known.
[0006] Magnetic circuit capable of controlling magnetic field
easily by supplying control current thereto is used in the
magnetostrictive actuator. Applying the magnetic field generated by
the magnetic circuit to the magnetostrictive element allows
displacement of the magnetostrictive element to be controlled. As
the magnetostrictive material, an Ni magnetostrictive alloy, a
Fe-Al magnetostrictive alloy, a ferrite magnetostrictive alloy have
been often used. Further, rare earth metal and transition metal
magnetostrictive supperalloy that generates displacement with an
order of magnitude too large as compared by these magnetostrictive
materials has been developed for commercial use.
[0007] The magnetostrictive element generates displacement along
its extension or compressive direction based on strength of the
applied magnetic field, not a direction of the magnetic field.
Thus, to the magnetostrictive element that generates displacement
along its extension direction, for example, initial displacement
such that static magnetic bias field is previously applied thereto
and the magnetostrictive element can be extended by only an order
applied by the magnetic bias field is applied. In a condition where
such the static magnetic bias field is previously applied thereto,
if magnetic field generated by the magnetic circuit is applied to
the magnetostrictive element, the element can be further displaced
along its extension or compressive direction from the initial
displacement condition based on the magnetic field generated by the
magnetic circuit. In other words, the magnetostrictive element can
generates displacement based on control current. Alternatively, if
the magnetostrictive element generates displacement along its
compressive direction, the static magnetic bias field is previously
applied to the magnetostrictive element so that any initial
displacement can be applied to the magnetostrictive element by
compressing it by only an order applied by the magnetic bias field,
thereby allowing additional displacement to be generated in the
magnetostrictive element based on control current. By disposition
of any permanent magnet in a magnet circuit, application of the
static magnetic bias field to the magnetostrictive element can be
carried out. Namely, the disposition of permanent magnet in the
magnet circuit causes magnetic field generated by the permanent
magnet to be applied to the magnetostrictive element as the static
magnetic bias field.
[0008] If external stress (hereinafter referred to as "prestress")
is previously applied to the magnetostrictive element, larger
displacement occurs when applying magnetic field thereto as
compared by a case where no prestress is applied thereto. Thus, any
prestress has been often applied to magnetostrictive actuator using
any magnetostrictive element to increase its displacement. The
prestress depends on material constituting the magnetostrictive
element. For example, in Ni magnetostrictive alloy, displacement
occurs in its compressive direction so that an initial strain
stress is applied as prestress, thereby obtaining larger
displacement. In each of the Fe-Al magnetostrictive alloy, ferrite
magnetostrictive alloy, and rare earth metal and transition metal
magnetostrictive supperalloy, on the other hand, displacement
occurs in its extension direction so that an initial compressive
stress is applied as prestress, thereby obtaining larger
displacement.
[0009] Japanese Patent Application Publication No. H07-15053
discloses a magnetostrictive actuator, as shown in FIG. 1,
including a rod-like magnetostrictive element 31 made of
magnetostrictive alloy, a solenoid coil 32, which arranged around
the magnetostrictive element 31, for applying controlling magnetic
field to the magnetostrictive element 31, a driving rod 33
connected to an end of the magnetostrictive element 31 to propagate
any displacement outputs of the magnetostrictive actuator, a fixed
base plate 34 connected to the other end of the magnetostrictive
element 31, a tubular case 35 attached to the fixed base plate 34
so as to be arranged around the solenoid coil 32. A permanent
magnet 36 is attached to the fixed base plate 34. The permanent
magnet 36 allows the magnetic bias field to be applied to the
magnetostrictive element 31.
[0010] The driving rod 33 and the cylinder-like case 35 are
connected to each other thorough the flexible connecting part 37.
The flexible connecting part 37 is connected to the driving rod 33
and the tubular case 35 so that it can be flexible in a driving
direction of the magnetostrictive actuator but solid in a direction
perpendicular to the driving direction. This connecting part 37 has
a configuration such that it has little effect on the displacement
output of the magnetostrictive element 31, thereby realizing a
design to decrease in a loss of the displacement output
thereof.
SUMMARY OF THE INVENTION
[0011] In the above magnetostrictive actuator, as shown in FIG. 1,
in order to allow the magnetostrictive actuator to gain larger
displacement, the connecting part 37 has been previously bent,
thereby allowing its restoring force to apply a prestress to the
magnetostrictive element 31. If, however, a period of displacement
is too short when such the restoring force is used, it is difficult
for a restoration of the connecting part 37 to follow the
displacement of magnetostrictive element 31. This results in
applying a prestress to the magnetostrictive element 31 unstably.
Further, applying a prestress to the magnetostrictive element 31
unstably may gain no displacement output according to the control
current when the current is flown through the solenoid coil 32.
[0012] Additionally, the permanent magnet 36 is attached to the
fixed base plate 34 so that a magnetic bias field applied to the
magnetostrictive element 31 can become stronger at a side of the
fixed base plate 34 of the magnetostrictive element 31 but weaker
at side of the driving rod 33 thereof. This may prevent uniformed
magnetic bias field from being applied to the magnetostrictive
element 31.
[0013] It is desirable to provide an magnetostrictive actuator that
is capable of gaining larger displacement output with decreasing a
loss of the displacement output and easy to be downsized at a
relatively low cost.
[0014] According to an embodiment of the invention, there is
provided a magnetostrictive actuator having displacement-generating
means configured to generate a displacement caused by magnetic
material having a magnetostrictive. The actuator also has movable
means configured to move in a displacement direction of the
displacement-generating means. The movable means is connected with
the displacement-generating means and made of a ferromagnet. The
actuator further has magnetic-field-generating means configured to
apply magnetic field to the displacement-generating means. The
magnetic-field-generating means is arranged around the
displacement-generating means. The actuator additionally has
enclosing device configured to enclose the displacement-generating
means and the movable means.
[0015] In the enclosing means, magnetic-circuit-forming member
including a ferromagnet and a permanent magnet for applying static
magnetic bias field to the displacement-generating means are
arranged around the enclosed displacement-generating means. The
movable means is arranged in the enclosing means with a space,
thereby allowing magnetic pull-in force caused between the movable
means and the enclosing means to apply prestress to the
displacement-generating means.
[0016] The sealing member having flexibility seals the space
between the movable means and the enclosing means. In the enclosing
means, a plurality of permanent magnets is arranged in a
displacement direction of the displacement-generating means with an
interval therebetween.
[0017] According to another embodiment of the invention, there is
also provided a magnetostrictive actuator having
displacement-generating device configured to generate a
displacement caused by magnetic material having a magnetostrictive.
The actuator also has movable member configured to move in a
displacement direction of the displacement-generating device. The
movable member is connected with the displacement-generating device
and made of a ferromagnet. The actuator further has
magnetic-field-generating device configured to apply magnetic field
to the displacement-generating device. The
magnetic-field-generatin- g device is arranged around the
displacement-generating device. The actuator additionally has
enclosing device configured to enclose the displacement-generating
device and the movable member.
[0018] In the enclosing device, magnetic-circuit-forming member
including a ferromagnet and a permanent magnet for applying static
magnetic bias field to the displacement-generating device are
arranged around the enclosed displacement-generating device. The
movable member is arranged in the enclosing device with a space,
thereby allowing magnetic pull-in force caused between the movable
member and the enclosing device to apply prestress to the
displacement-generating device.
[0019] The concluding portion of this specification particularly
points out and directly claims the subject matter of the present
invention. However those skill in the art will best understand both
the organization and method of operation of the invention, together
with further advantages and objects thereof, by reading the
remaining portions of the specification in view of the accompanying
drawing(s) wherein like reference characters refer to like
elements.
[0020] According to the embodiments of the invention, magnetic
pull-in force caused between the movable member and the enclosing
device is allowed to apply prestress to the displacement-generating
device. Since no friction with a bearing for supporting the movable
member occurs, it is possible to decrease a loss of the
displacement output of the magnetostrictive actuator significantly.
Further, by magnetic pull-in force, any prestress is applied to the
displacement-generating device, so that, even if a period of
displacement in the displacement-generating device is too short, it
is possible to keep applying the prestress thereto, thereby gaining
a proper displacement output. Since a bearing for supporting the
movable member, a connecting member for connecting the movable
member and the enclosure, a spring or the like for applying the
prestress to the displacement-generating device are not necessary
to be provided, it is possible to make the magnetostrictive
actuator easily downsized at a relatively low cost.
[0021] The sealing member having flexibility seals the space
between the movable means and the enclosing means. This avoids
foreign body from being inserted into the magnetostrictive actuator
to adversely affecting operations of the magnetostrictive actuator.
The sealing member has flexibility so that it is possible for the
sealing member to decrease a loss of the displacement output of the
magnetostrictive actuator.
[0022] Further, in the enclosure, a plurality of permanent magnets
is arranged in a displacement direction of the
displacement-generating means with an interval therebetween. Thus,
it is possible to make magnetic bias field that is applied to the
displacement-generating device more uniform.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a conceptually cross-sectional diagram for showing
a configuration of a magnetostrictive actuator according to related
art;
[0024] FIG. 2 is a conceptually cross-sectional diagram for showing
a configuration of a first embodiment of a magnetostrictive
actuator according to the invention;
[0025] FIG. 3 is a diagram for showing magnetic flux lines in the
first embodiment;
[0026] FIG. 4 is a conceptually cross-sectional diagram for showing
a configuration of a second embodiment of a magnetostrictive
actuator according to the invention;
[0027] FIG. 5 is a conceptually cross-sectional diagram for showing
a configuration of a third embodiment of a magnetostrictive
actuator according to the invention;
[0028] FIG. 6 is a diagram for showing magnetic flux lines in the
third embodiment; and
[0029] FIG. 7 is a conceptually cross-sectional diagram for showing
a configuration of a fourth embodiment of a magnetostrictive
actuator according to the invention.
DESCRIPTION OF THE INVENTION
[0030] The following will describe embodiments of the present
invention with reference to drawings. FIG. 2 shows a configuration
of a first embodiment of a magnetostrictive actuator 10a according
to the invention. The magnetostrictive actuator 10a has a rod-like
magnetostrictive element 11 as displacement-generating device
generating a displacement in a extending direction, solenoid coil
12 as magnetic-field-generating device applying magnetic field to
the magnetostrictive element 11, which is arranged around the
magnetostrictive element 11, a driving rod 13 as the movable member
transmitting the displacement output of the magnetostrictive
actuator 10a by being connected with an end of the magnetostrictive
element 11, the enclosure 14 enclosing the magnetostrictive element
11 and the solenoid coil 12.
[0031] The enclosure 14 has a fixed base plate 141, a permanent
magnet 142, and tubular cases 143. To the fixed base plate 141, the
other end of the magnetostrictive element 11 is connected and the
fixed base plate 141 supports the magnetostrictive element 11. The
permanent magnet 142 applying static magnetic bias field to the
magnetostrictive element 11, and the tubular cases 143 as
magnetic-circuit-forming member are arranged around the enclosed
magnetostrictive element 11. The tubular cases 143 are arranged at
both sides of the driving rod 13 and the fixed base plate 141 of
the permanent magnet 142. By being manufactured by a ferromagnet,
the tubular cases 143 can effectively apply the static magnetic
bias filed to the magnetostrictive element 11. By being also
manufactured by a ferromagnet, the fixed base plate 141 also can
further effectively apply the static bias magnetic filed to the
magnetostrictive element 11.
[0032] The driving rod 13 is arranged in the enclosure 14 with a
space, and the driving rod 13 is made of ferromagnet also so that
the rod 13 can be pulled in by the permanent magnet 142. This
allows magnetic pull-in force to be generated between the driving
rod 13 and the enclosure 14 to apply the prestress to the
magnetostrictive element 11 equipped with the driving rod 13.
[0033] FIG. 3 shows magnetic flux lines in the first embodiment.
The magnetic flux lines starting from the permanent magnet 142
passes through one of the tubular cases 143 towards the permanent
magnet 142 via the space 15, the driving rod 13, the fixed base
plate 141, and the other tubular case 143. This allows magnetic
pull-in force to be generated between the driving rod 13 and the
enclosure 14, thereby applying the prestress to the
magnetostrictive element 11 by the force. Part of the magnetic flux
lines also passes through the one of tubular cases 143 towards the
permanent magnet 142 via the space 15, the driving rod 13, the
magnetostrictive element 11, the fixed base plate 141, and the
other tubular case 143. Thus, this allows the static magnetic bias
field to be applied to the magnetostrictive element 11.
[0034] In the magnetostrictive actuator 10a thus configured, no
bearing supports the driving rod, so that any friction of the
bearing with the driving rod 13 occurs, thereby decrease a loss of
the displacement output of the magnetostrictive actuator 10a
significantly. Further, the prestress is applied to the
magnetostrictive element 11 by the magnetic full-in force, so that
even if a period of displacement of the magnetostrictive element 11
is too short, the actuator 10a keeps the prestress to be applied to
it with stability, thereby gaining a proper displacement output
according to the control current supplied to the solenoid coil 12.
The permanent magnet 142 intervenes between two tubular cases 143.
This allows static magnetic bias field applied to the
magnetostrictive element 11 to be made uniform by comparing a case
where a permanent magnet is arranged on a position of the fixed
base plate 141. Further, since a bearing for supporting the movable
member, a connecting member for connecting the movable member and
the enclosure, a spring or the like for applying the prestress to
the displacement-generating device are not necessary to be
provided, it is possible to make the magnetostrictive actuator
easily downsized at a relatively low cost.
[0035] In the first embodiment, however, the space 15 is arranged
between the driving rod 13 and the enclosure 14 so that a foreign
body may be inserted from the space into inside. The following will
describe a magnetostrictive actuator 10b that prevents the foreign
body from being inserted into inside.
[0036] FIG. 4 shows a configuration of a second embodiment of
magnetostrictive actuator according to the invention. In FIG. 4,
like members corresponding to the ones shown in FIG. 1 are applied
to like symbols, a description of which will be deleted.
[0037] In the second embodiment of the magnetostrictive actuator
10b, sealing member 16 is inserted into the space 15 of the first
embodiment. As the sealing member 16, in order to prevent a loss of
the displacement output from resulting in the magnetostrictive
actuator 10b, materials of a low hardness having flexibility such
as silicon-based resin or rubber-based resin are used. As the
sealing member 16, magnetic flux or the like may be used to seal
the space 15. Thus, according to the second embodiment, the space
15 is sealed to prevent the foreign body from being inserted into
the inside of the magnetostrictive actuator, thereby avoiding the
foreign body from being inserted into inside to adversely affecting
operations of the magnetostrictive actuator.
[0038] The following will describe a third embodiment of a
magnetostrictive actuator of the invention. The third embodiment
refers to a magnetostrictive actuator 10c that is possible of
making the static magnetic bias field applied to the
magnetostrictive element 11 more uniform as compared by the above
cases of the first and second embodiments.
[0039] FIG. 5 shows a configuration of a third embodiment of
magnetostrictive actuator according to the invention. In FIG. 5,
like members corresponding to the ones shown in FIG. 1 are applied
to like symbols, a description of which will be deleted.
[0040] In the magnetostrictive actuator 10c, in order to make the
static magnetic bias field applied to the rod-like magnetostrictive
element 11 uniform, a plurality of permanent magnets 142 is
arranged in a displacement direction of the magnetostrictive
element 11 (i.e. an axis direction of the rod-like magnetostrictive
element 11) with an interval therebetween. For example, as shown in
FIG. 5, a first permanent magnet 142a is arranged in a side of the
driving rod 13. On the other hand, a third permanent magnet 142c is
arranged in a side of the fixed base plate 141. Further, a second
permanent magnet 142b is arranged in a middle of the first and
third permanent magnets 142a and 142c. Each of the tubular cases
143 is arranged between the first and second permanent magnets 142a
and 142b and between the second and third permanent magnets 142b
and 142c. Thus, a plurality of permanent magnets 142 is arranged in
a displacement direction of the magnetostrictive element 11 with an
interval therebetween, thereby applying static magnetic bias field
to the magnetostrictive element 11.
[0041] FIG. 6 shows magnetic flux lines in the third embodiment.
The magnetic flux lines starting from the three permanent magnets
142a through 142c passes through the tubular cases 143 towards the
permanent magnets 142a through 142c via the space 15, the driving
rod 13, and the fixed base plate 141. This allows magnetic pull-in
force to be generated between the driving rod 13 and the magnet
142a, thereby applying the prestress to the magnetostrictive
element 11 by the force. Part of the magnetic flux lines also
passes through the tubular cases 143 towards the permanent magnets
142 via the space 15, the driving rod 13, the magnetostrictive
element 11, and the fixed base plate 141. Thus, this allows the
static magnetic bias field to be applied to the magnetostrictive
element 11. Further, the permanent magnets 142a through 142c are
arranged in a displacement direction of the magnetostrictive
element 11 so that they can make the static magnetic bias field
applied to the magnetostrictive element 11 more uniform, as
compared by each of the cases of the first and second embodiments
where one permanent magnet is arranged.
[0042] Thus, according to the third embodiment, as the first
embodiment, it is possible to decrease a loss of the displacement
output of the magnetostrictive actuator 10c significantly. Further,
it is also possible to gain proper displacement output according to
the control current supplied to the solenoid coil 12 and easily
down-size it. It is further possible to make more uniform the
static magnetic bias field applied to the magnetostrictive element
11.
[0043] The following will describe a fourth embodiment of this
invention in which sealing member 16 seals the space 15 of the
third embodiment as the second embodiment. FIG. 7 shows a
configuration of the fourth embodiment of a magnetostrictive
actuator 10d according to the invention. In FIG. 7, like members
corresponding to the ones shown in FIG. 1 are applied to like
symbols, a description of which will be deleted.
[0044] In the fourth embodiment of the magnetostrictive actuator
10d, the sealing member 16 is inserted into the space 15 of the
third embodiment. As the sealing member 16, in order to prevent a
loss of the displacement output from resulting in the
magnetostrictive actuator 10d, materials of a low hardness having
flexibility are used as the second embodiment.
[0045] Thus, according to the fourth embodiment, the sealing member
16 seals the space 15 to prevent the foreign body from being
inserted into the inside of the magnetostrictive actuator, thereby
avoiding the foreign body from being inserted into the inside to
adversely affecting operations of the magnetostrictive
actuator.
[0046] In the first embodiment, the magnetostrictive element 11 is
made of terbium-dysprosium-iron (Th-Dy-Fe) alloy having its
component of Th.sub.0.33Dy.sub.0.66Fe.sub.1.9. This
magnetostrictive element 11 has a diameter of 1.0 mm and a length
of 10 mm. The driving rod 13 and the tubular cases 143 are made of
carbon steel S15C. Each of the tubular cases 143 has an inner
diameter of 4.5 mm, an outer diameter of 8.0 mm, and a length of
4.0 mm. An outer diameter of the driving rod 13 is similar to those
of each of the tubular cases 143 or the permanent magnet 142a. As
the permanent magnets 142, 142a, 142b, and 142c,
neodymium-iron-boron (Nd-Fe-B) magnet, for example, NEOMAX 32H, a
magnet made by NEOMAX MATERIALS Co., Ltd. having maximum energy
product, BHmax of 32MGOe are used. Each of them has an inner
diameter of 4.5 mm, an outer diameter of 8.0 mm, and a length of
3.0 mm and their direction of magnetization is displacement
direction of the magnetostrictive element 11. If the space 15 is
provided as having its amount of clearance of 0.2 mm, a calculation
result of compressive force applied to the magnetostrictive element
11 was 1.3.times.10.sup.6 N/m.sup.2. Further, in the third
embodiment, when a height of each of the permanent magnets 142,
142a, 142b, and 142c is set to 1.0 mm, a calculation result of
compressive force applied to the magnetostrictive element 11 was
8.0.times.10.sup.6 N/m.sup.2. Thus, the driving rod 13 is mounted
to the enclosure 14 with the space 15 so that compressive force can
be applied to the magnetostrictive element 11.
[0047] As described above, the embodiments of the magnetostrictive
actuator of the invention is available to an actuator having a good
response and a little loss of the displacement and is preferably
applied to various kinds of fields, for example,
vibration-controlling apparatus, positioning apparatus, voice
output apparatus, and a pump.
[0048] Thus have been described the magnetostrictive actuator. It
should be understood by those skilled in the art that various
modifications, combinations, sub-combinations and alternations may
occur depending on design requirements and other factors insofar as
they are within the scope of the appended claims or the equivalents
thereof.
* * * * *