U.S. patent application number 09/874983 was filed with the patent office on 2003-05-22 for linear oscillating actuator.
This patent application is currently assigned to Matsushita Electric Works, Ltd.. Invention is credited to Kobayashi, Noboru, Motohashi, Ryo, Nishinaka, Takahiro, Shimizu, Hiroaki, Yabuuchi, Hidekazu.
Application Number | 20030094861 09/874983 |
Document ID | / |
Family ID | 26593519 |
Filed Date | 2003-05-22 |
United States Patent
Application |
20030094861 |
Kind Code |
A1 |
Shimizu, Hiroaki ; et
al. |
May 22, 2003 |
LINEAR OSCILLATING ACTUATOR
Abstract
An improved linear oscillating actuator is capable of minimizing
the undesired vibrations while moving first and second oscillators
in parallel paths. The first and second oscillators carry first and
second drive elements respectively for driving connection to
individual reciprocating loads. The first and second drive elements
project upwardly respectively from the first and second oscillators
such that the first drive element is disposed immediately upwardly
of the second oscillator and the second drive elements is disposed
immediately upwardly of the first oscillator. With this reverse
arrangement of the first and second drive elements relative to the
first and second oscillators, the individual oscillating systems
each including the oscillator, the drive element and the
corresponding reciprocating load can have its mass center disposed
in close proximity to a mass center of the actuator, thereby
enabling to reduce undesired vibrations which would otherwise occur
around the mass center of the actuator.
Inventors: |
Shimizu, Hiroaki;
(Hikone-shi, JP) ; Motohashi, Ryo; (Hikone-shi,
JP) ; Yabuuchi, Hidekazu; (Hikone-shi, JP) ;
Nishinaka, Takahiro; (Ohmihachiman-shi, JP) ;
Kobayashi, Noboru; (Hikone-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Matsushita Electric Works,
Ltd.
Kadoma-shi
JP
|
Family ID: |
26593519 |
Appl. No.: |
09/874983 |
Filed: |
June 7, 2001 |
Current U.S.
Class: |
310/36 |
Current CPC
Class: |
B26B 19/282 20130101;
B26B 19/288 20130101; H02K 33/10 20130101 |
Class at
Publication: |
310/36 |
International
Class: |
H02K 041/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 7, 2000 |
JP |
2000-171269 |
Jun 7, 2000 |
JP |
2000-171271 |
Claims
What is claimed is:
1. A linear oscillating actuator comprising: a stator having one of
an electromagnet and a permanent magnet; first and second
oscillators each having the other of said electromagnet and said
permanent magnet; a chassis fixedly mounting said stator and
movably supporting said first and second oscillators in such a
manner as to allow them to move respectively in parallel linear
paths; said electromagnet including a winding receiving a drive
current to generate a magnetic field which interacts with the
permanent magnet to cause said oscillators to reciprocate relative
to said stator respectively in the parallel linear paths; a first
drive element integrally projecting from said first oscillator and
being adapted to be connected to a reciprocating load for driving
the same; and a second drive element integrally projecting from
said second oscillator and being adapted to be connected to a
reciprocating load for driving the same; wherein said first and
second drive elements project upwardly respectively from said first
and second oscillators such that said first drive element is
disposed immediately upwardly of said second oscillator and said
second drive elements is disposed immediately upwardly of said
first oscillator.
2. The linear oscillating actuator as set forth in claim 1, wherein
said first and second oscillators have lengths respectively
extending along the linear paths, and have respective upright axes,
said first drive element being integrally connected to a lengthwise
center of said first oscillator by way of a center stem which
extends obliquely with respect to the upright axis of said first
oscillator, said second drive element being integrally connected to
apposite lengthwise ends of said second oscillator by way of a gate
which is offset laterally in a direction perpendicular to the
length of said second oscillator, and said gate having an opening
though which said center stem extends loosely so that said first
drive element is allowed to oscillate without being jammed with
said second drive element.
3. The linear oscillating actuator as set forth in claim 2, wherein
a reinforcement fin projects on top of the first oscillator and
merges into a juncture of the center stem with the first
oscillator, said reinforcement fin extending in the lengthwise
direction of the first oscillator over a distance greater than a
lengthwise dimension of the center stem measured with respect to
the length of the first oscillator.
4. The linear oscillating actuator as set forth in claim 3, wherein
said gate comprises a bridge anchored at its opposite lengthwise
ends to the lengthwise ends of said second oscillator so as to
define said opening between the bridge and the second oscillator,
said reinforcement fin opposing said bridge with a small clearance
therebetween so as to be capable of bearing the bridge when the
second drive element is depressed.
5. The linear oscillating actuator as set forth in claim 2, wherein
said gate comprises a bridge anchored at its opposite lengthwise
ends to the lengthwise ends of said second oscillator so as to
define said opening between the bridge and the second oscillator,
said bridge being formed at its lengthwise center with a raised
platform from which said second drive element projects.
6. The linear oscillating actuator as set forth in claim 1, wherein
said first and second oscillators have respective legs for anchored
connection with said chassis, said actuator further including a
link which interlocks the first and second oscillators in such a
manner as to oscillate the oscillators in opposite phase, and the
leg of each of said first and second oscillators being connected to
said link at a point below the anchored connection of said leg with
said chassis.
7. The linear oscillating actuator as set forth in claim 1, wherein
a reinforcement member is embedded in the center stem of said first
oscillator.
8. The linear oscillating actuator as set forth in claim 7, wherein
said reinforcement member is in the form of a metal pin.
9. The linear oscillating actuator as set forth in claim 7, wherein
said reinforcement member is defined by a part of a metal pin
projecting through the first drive element for driving connection
with the reciprocating load.
10. The linear oscillating actuator as set forth in claim 7,
wherein said reinforcement member is a part of a back yoke provided
in the first oscillator adjacent to the permanent magnet.
11. The linear oscillating actuator as set forth in claim 1,
wherein said first and second oscillators are suspended from said
chassis by means of respective leaf springs, each of said leaf
springs having a portion wider than a thickness of a corresponding
one of said first and second oscillators, and said leaf springs
being offset relative to the corresponding ones of said first and
second oscillators in the thickness direction thereof, while being
disposed close to each other in the thickness direction.
12. The linear oscillating actuator as set forth in claim 11,
wherein said leaf spring is connected at its upper end with said
chassis and at its lower end with one of said first and second
oscillators, the lower end of said leaf spring having a width
substantially equal to that of the upper end of said leaf
spring.
13. The linear oscillating actuator as set forth in claim 11,
wherein said leaf spring is connected at its upper end with said
chassis and at its lower end with one of said first and second
oscillators, the lower end of said leaf spring having a width less
than the upper end of said leaf spring.
14. The linear oscillating actuator as set forth in claim 11,
wherein said leaf spring is connected at its upper end with said
chassis and at its lower end with one of said first and second
oscillators, the lower end of said leaf spring carrying a joint
which is molded from a plastic material to have a means for
connection with the corresponding one of the first and second
oscillators.
15. The linear oscillating actuator as set forth in claim 14,
wherein said leaf spring is formed at its lower end with a hole
into which a portion of said joint engages for firmly securing the
joint to the leaf spring.
16. The linear oscillating actuator as set forth in claim 14,
wherein said joint has a projection which is inserted into a recess
formed in the lower end of the corresponding one of the first and
second oscillators.
17. The linear oscillating actuator as set forth in claim 16,
wherein said projection has cross-section smaller than that of the
joint.
18. The linear oscillating actuator as set forth in claim 1,
wherein said stator has the electromagnet composed of a core and
the winding disposed around the core, said core having an upper end
which opposes said permanent magnets provided on the side of the
first and second oscillators to define therebetween a magnetic gap,
and said core being formed at its lower end with an extension
having a stator's mating surface which abuts against a chassis's
mating surface at a corresponding portion of said chassis for
welding connection of said stator with said chassis.
19. The linear oscillating actuator as set forth in claim 18,
wherein both of said stator's mating surface and said chassis's
mating surface are flat horizontal surfaces.
20. The linear oscillating actuator as set forth in claim 18,
wherein said extension includes a first stopper which engages with
the chassis to fix said stator to said chassis with respect to a
longitudinal direction along said linear path.
21. The linear oscillating actuator as set forth in claim 20,
wherein said extension includes a second stopper which engages with
the chassis to fix said stator to said chassis with respect to a
lateral direction perpendicular to said longitudinal direction.
22. The linear oscillating actuator as set forth in claim 20,
wherein a coil bobbin is interposed between said core and said
winding, said core having a means for latching engagement with said
coil bobbin.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention is directed to a linear oscillating
actuator, and more particularly to a linear oscillating actuator
having a pair of oscillators moving in parallel paths for driving
individual loads.
[0003] 2. Description of the Prior Art
[0004] A linear oscillating actuator has been utilized in many
fields as an alternative to the rotary driving source.
Particularly, as disclosed in U.S. Pat. No. 5,632,087, the linear
actuator has found itself advantageous for use as a driving source
of dry shavers of reciprocatory type. When applied to the shaver
having a pair of inner cutters, i.e., the reciprocating loads, the
linear oscillating actuator is designed to have a corresponding
pair of oscillators running in parallel oscillating paths and being
adapted for driving connection respectively with the inner cutters.
In this instance, each individual oscillating system composed of
the oscillator and the corresponding reciprocating load has its
mass center offset in a lateral direction perpendicular to the
oscillating direction from a mass center of the actuator or the
shaver. Due to this offset arrangement of the individual
oscillating systems from the mass center of the actuator, the
actuator suffers from undesired vibrations around its mass
center.
SUMMARY OF THE INVENTION
[0005] The present invention has been achieved in view of the above
problem to provide an improved linear oscillating actuator which is
capable of minimizing the undesired vibrations, while moving a pair
of oscillators in parallel paths. The linear oscillating actuator
in accordance with the present invention includes a stator having
one of an electromagnet and a permanent magnet, first and second
oscillators each having the other of the electromagnet and the
permanent magnet, and a chassis fixedly mounting the stator and
movably supporting the first and second oscillators in such a
manner as to allow them to move respectively in parallel linear
paths. The electromagnet includes a winding receiving a drive
current to generate a magnetic field which interacts with the
permanent magnet to cause the oscillators to oscillate relative to
the stator respectively in the parallel linear paths. A first drive
element integrally projects from the first oscillator and is
adapted to be connected to a reciprocating load for driving the
same, while the second drive element integrally projects from the
second oscillator and is adapted to be connected to a reciprocating
load for driving the same. An important feature of the present
invention resides in that the first and second drive elements
project upwardly respectively from the first and second oscillators
such that the first drive element is disposed immediately upwardly
of the second oscillator and the second drive elements is disposed
immediately upwardly of the first oscillator. With this reverse
arrangement of the first and second drive elements relative to the
first and second oscillators, the individual oscillating systems
each including the oscillator, the drive element and the
corresponding reciprocating load can have its mass center disposed
in close proximity to a mass center of the actuator, thereby
enabling to reduce undesired vibrations which would otherwise occur
around the mass center of the actuator.
[0006] The first and second oscillators are configured to have
lengths respectively extending along the liner paths and to have
respective upright axes. In a preferred embodiment, the first drive
element is integrally connected to a lengthwise center of the first
oscillator by way of a center stem which extends obliquely with
respect to the upright axis of the first oscillator, while the
second drive element is integrally connected to opposite lengthwise
ends of the second oscillator by way of a gate which is offset
laterally in a direction perpendicular to the length of the second
oscillator. The gate has an opening through which the center stem
of the first oscillator extends loosely so that the first drive
element is allowed to oscillate without being jammed with the
second drive element. Thus, the first and second drive elements can
be successfully disposed respectively immediately above the second
and first oscillators without sacrificing the oscillatory
movement.
[0007] Projecting on top of the first oscillator is a reinforcement
fin which merges into the juncture of the center stem with the
first oscillator. The reinforcement fin extends in the lengthwise
direction of the first oscillator over a distance greater than the
lengthwise dimension of the center stem measured with respect to
the length of the first oscillator. With the inclusion of the
reinforcement tin, the first oscillator is given sufficient
rigidity against deforming force acting in the lengthwise direction
along the oscillating path, assuring a stable and reliable
oscillating performance.
[0008] The gate on the side of the second oscillator is shaped to
have a bridge anchored at its opposite ends to the lengthwise ends
on top of the second oscillator so as to define the opening between
the bridge and the second oscillator. The reinforcement fin opposes
the bridge with a small clearance therebetween so as to be capable
of bearing the bridge when the second drive element is depressed.
Thus, the gate can be protected against a possible impact or stress
applied to the reciprocating load or the second drive element.
[0009] Further, the bridge may be formed at its longitudinal center
with a raised platform from which the second drive element projects
in order to strengthen the joint between the second drive element
and the second oscillator sufficiently to withstand the impact or
stress applied to the second drive element.
[0010] The first and second oscillators have respective legs for
anchored connection with the chassis. Further included in the
actuator is a link which interlocks the first and second
oscillators in such a manner as to oscillate the oscillators in
opposite phase. In this connection, the leg of each of the first
and second oscillators is connected to the link at a point below
the anchored connection of the leg with the chassis. That is, each
oscillator is connected to the chassis and also to the link at
vertically spaced points, thereby requiring no extra dimensions
with respect to the longitudinal and lateral directions for the
interlocking connection, and therefore contributing to a compact
design.
[0011] The center stem of the first oscillator can be given
increased rigidity by a reinforcement member embedded therein. The
reinforcement member may be either in the form of a metal pin or a
part of a back yoke provided in the first oscillator adjacent to
the permanent magnet. The metal pin may project out of the first
drive element for driving connection with the reciprocating
load.
[0012] The first and second oscillators are suspended from the
chassis by means of respective leaf springs so that the oscillators
are movable only along the linear oscillating paths under the bias
of the springs. Each leaf spring has a portion wider than a
thickness of a corresponding one of the first and second
oscillators so as to be given sufficient resistance to a torsion
for stably supporting the oscillator. The leaf spring is offset
laterally relative to the corresponding ones of the first and
second oscillators in the thickness direction thereof, while being
disposed close to each other in the thickness direction. Thus, the
first and second oscillators can be held close to each other, yet
allowing the use of the leaf springs having the wider portion than
the thickness of the oscillator. Whereby, it is possible to make
compact the actuator in the thickness direction of the oscillators
while stably supporting the oscillators to the chassis.
[0013] In a preferred embodiment, the leaf spring is connected at
its upper end with the chassis and at its lower end with one of the
first and second oscillators. The lower end of the leaf spring may
be configured to have a width either substantially equal to or less
than that of the upper end of the leaf spring.
[0014] Further, in order to facilitate the connection of the leaf
spring to the oscillator, the leaf spring may carry at its lower
end a joint which is molded from a plastic material to have a means
for connection with the corresponding one of the first and second
oscillators. In this connection, the leaf spring may be formed with
a hole into which a portion of the joint engages for firmly
securing the joint to the leaf spring. The joint has a projection
for insertion into a recess formed in the lower end of the
corresponding one of the first and second oscillators.
[0015] The present invention further discloses a unique structure
of mounting the stator to the chassis. The stator has the
electromagnet composed of a core and the winding disposed around
the core. The core has an upper end which opposes the permanent
magnet on the side of the first and second oscillators to define
therebetween a magnetic gap. The core is formed at its lower end
with an extension having a stator's mating surface which abuts
against a chassis's mating surface at a corresponding portion of
the chassis for welding connection of the stator with the chassis.
Preferably, both of the stator's mating surfaces and the chassis's
mating surface are finished as flat horizontal surfaces.
[0016] The extension may also include a first stopper which engages
with the chassis to fix the stator thereto with respect to a
longitudinal direction along the linear path, and a second stopper
which engages with the chassis to fix the stator thereto with
respect to a lateral direction perpendicular to the longitudinal
direction. Thus, the stator can be positioned accurately relative
to the chassis without requiring external jig.
[0017] Further, the core may be given a means for latching
engagement with a coil bobbin interposed between the core and the
winding for stably holding the coil bobbin in position.
[0018] These and still other objects and advantageous features of
the present invention will become more apparent from the following
description of the embodiments when taken in conjunction with the
attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a perspective view of a linear oscillating
actuator in accordance with a preferred embodiment of the present
invention;
[0020] FIG. 2 is a front view of the actuator;
[0021] FIG. 3 is a side view of the actuator;
[0022] FIG. 4 is an exploded perspective view of the actuator;
[0023] FIGS. 5A and 5B are front and side view of a first
oscillator utilized in the actuator;
[0024] FIGS. 6A and 6B are front and side view of a second
oscillator utilized in the actuator;
[0025] FIGS. 7A, 7B, and 7C are front, side, and top views of a
combination of the first and second oscillators;
[0026] FIG. 8 is a sectional view taken along line 8-8 of FIG.
7A;
[0027] FIG. 9 is a sectional view of the first oscillator;
[0028] FIG. 10 is a perspective view of an internal structure of
the first oscillator;
[0029] FIGS. 11 to 13 are views respectively illustrating modified
structures of the first oscillator;
[0030] FIG. 14 is an exploded perspective view showing connections
of the first and second oscillators to associated leaf springs,
respectively;
[0031] FIG. 15 is a sectional view of a part of the oscillator;
[0032] FIGS. 16A and 16B are partial views of the lower end of the
leaf spring, respectively;
[0033] FIGS. 17A and 17B are partial views of the lower end of a
modified leaf spring, respectively;
[0034] FIGS. 18A and 18B are partial views of the lower end of a
modified leaf spring shown with a corresponding portion of the
oscillator, respectively;
[0035] FIGS. 19A and 19B are partial views of the lower end of a
modified leaf spring shown with a corresponding portion of the
oscillator, respectively;
[0036] FIGS. 20 and 21 are perspective views illustrating the
chassis and the core viewed respectively from different
directions;
[0037] FIGS. 22 and 23 are perspective views illustrating the
chassis and a modified core viewed respectively from different
directions.
[0038] FIG. 24 is a front view partly in section of the combination
of a core and a coil bobbin of the stator;
[0039] FIG. 25 is an exploded front view of the combination of the
core and the coil bobbin; and
[0040] FIG. 26 is a side view of a modified actuator in accordance
with the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENT
[0041] Now referring to FIGS. 1 to 4, there is shown a linear
oscillating actuator in accordance with the present invention which
is adapted to be incorporated in a dry shaver as a driving source
for oscillating a pair of inner cutters respectively in parallel
linear paths relative to an outer cutter. The actuator is basically
composed of a chassis 10 mounting a stator 20 and a pair of
oscillators, i.e., a first oscillator 40 and a second oscillator
60. The stator 20 is realized in the form of an electromagnet
composed of a core 22 and a pair of windings 24 disposed
respectively around two upright poles 23 of the core 22. The
windings 24 are connected in series and supplied with an
alternating current to generating a magnetic field of alternating
polarity. The first and second oscillators 40 and 60 are suspended
from the chassis 10 respectively by means of leaf springs 80 so as
to be movable only in the linear paths defined along a horizontal
length of the chassis 10. In this connection, the chassis 10 is has
the horizontal length, an upright axis defining the height of the
actuator, and a lateral width defining the width of the actuator.
The oscillators and the associated parts are explained in this
description to have a length along the horizontal length of the
chassis, to have a thickness along the lateral width of the
chassis, and to have a height along the upright axis of the chassis
10. The first and second oscillators 40 and 60 are provided
respectively with permanent magnet 44 and 54 which are so
magnetized to interact with the magnetic field of the electromagnet
for oscillating the oscillators along the lengthwise direction in a
reverse phase relation to each other. The first and second
oscillators are molded from a plastic material to have integral
first and second drive elements 50 and 70 which are adapted to be
connected with the inner cutters, i.e., the reciprocating loads for
driving the same.
[0042] As best shown in FIGS. 5A and 5B, the first oscillator 40 is
of a generally U-shaped configuration having a top bar 41 and a
pair of legs 42 depending from opposite ends of the top bar. The
first drive element 50 extends integrally from the longitudinal
center of the top bar 41 through an inclined stem 52 in such a
manner as to project upright but in a laterally offset relation
from the first oscillator 40. A drive pin 58 is inserted in the
first drive element 50 to project therefrom for connection with the
inner cutter. Embedded in the top bar 41 is a back yoke 43 which
backs up the permanent magnet 44. A reinforcement fin 45 of reduced
height extends integrally from the top bar 41 over a lengthwise
distance larger than the dimension of the stem 52 along the same
lengthwise distance and merges into the lower end of the stem 52,
thereby strengthening the connection of the drive element 50 with
the oscillator 40.
[0043] As shown in FIGS. 6A and 6B, the second oscillator 60 is of
generally identical configuration to the first oscillator 40 to
have a top bar 61 and a pair of opposed legs 62. The second drive
element 70 extends integrally from the second oscillator 60 through
a gate 71 which is of generally U-shaped configuration having a
horizontal bridge 72 and a pair of anchor legs 73 joining at the
respective lower ends to the opposite ends of the top bar 61. In
detail, the second drive element 70 projects upright from the
longitudinal center of the bridge 72 in a laterally offset relation
from the upright axis of the second oscillator 60. That is, the
gate 71 is itself offset laterally from the second oscillator 60
with the anchor legs 73 connected at its lateral ends to the top
bar 61 of the second oscillator 60, as shown in FIG. 6B. Formed
between the bridge 72 and the top bar 61 is an opening 74 through
which the stem 52 of the first drive element 50 extends such that,
as shown in FIGS. 7C and 8, the first drive element 50 is disposed
immediately upwardly of the second oscillator 60 and the second
drive element 70 is disposed immediately upwardly of the first
oscillator 40. The opening 74 has its lower boundary only defined
by the top bar 61 of the first oscillator laterally offset from the
bridge 72. This means that the opening 74 has its immediate bottom
left open such that the top bar 41 of the first oscillator 40 is
positioned immediately below the gate 71 and is kept in level with
the top bar 61 of the second oscillator 60. With this reverse
arrangement of the first and second drive elements 50 and 70
relative to the first and second oscillators 40 and 60, the
individual oscillating systems each including the oscillator, the
drive element and the corresponding reciprocating load can have its
mass center M1 and M2 disposed in close proximity to a mass center
of the actuator along the lateral direction perpendicular to the
longitudinal direction, i.e., the oscillating direction of the
oscillators, as shown in FIG. 8. That is, the individual mass
centers M1 and M2 can be aligned on or closely adjacent to a center
line CL when the reciprocating loads are attached to the individual
drive elements 50 and 60, Whereby it is possible to greatly reduce
undesired vibrations which would otherwise occur around an upright
axis passing through the mass center of the whole assembly, i.e.,
the actuator.
[0044] The second drive element 70 projects from a raised platform
75 which is formed at a longitudinal center of the bridge 72 and
has a recess 76 in its bottom to impart resistivity against an
impact which may be applied to the gate through the second drive
element. When the second oscillator 60 is combined with the first
oscillator 40, the reinforcement fin 45 of the first oscillator 40
is positioned just below the bridge 72 with a small clearance
therebetween, such that the reinforcement fin 45 can bear the
bridge 72 when the bridge is deformed as a consequence of the
second drive element being subject to the impact. The second drive
element 70 also includes a drive pin 78 for driving connection to
the inner cutter, i.e., the reciprocating load.
[0045] Interposed between the stem 52 of the first oscillator 40
and the anchor legs 73 of the second oscillator 60 are coil springs
90 which are cooperative with the leaf springs 80 to give restoring
forces for counteracting the magnetic driving force developed by
the electromagnet and therefore establishing the oscillation
system. The first and second oscillators 40 and 60 are interlocked
by means of a link 100 pivotally supported to the chassis 10 so
that the oscillators 40 and 60 oscillates in counter directions As
shown in FIG. 3, the link 100 has a hole 101 receiving a pivot axis
11 projecting on the bottom of the chassis 10, and has a pair of
pins 102 for loose engagement into corresponding pivot holes 49, 69
each formed in the bottom of the leg of each of the first and
second oscillators 40 and 60, as shown in FIG. 15.
[0046] As shown in FIGS. 9 and 10, the first oscillator 40 carries
a metal-made reinforcement member 53 which is embedded in a portion
extending from the top bar 41 through the stem 52 with its lower
end anchored to the back yoke 43 for imparting increased rigidity
to the connection between the first oscillator 40 and the first
drive element 50. In addition to the reinforcement effect, the
metal member 53 is incorporated to adjust the position of the mass
center for the oscillating system including the oscillator and the
drive element. The reinforcement member 53 may be formed integrally
with the drive pin 58, as shown in FIG. 11, or may be formed
integrally with the back yoke 43, as shown in FIG. 12. Further, the
reinforcement member 53 may be in the form of a pin anchored at its
lower end to the back yoke 43, as shown in FIG. 13.
[0047] Turning back to FIGS. 1 to 4, each of the leaf springs 80
carries at its upper end a fastener 81 for secure engagement with
the upper end of the chassis 10, and carries at its lower end a
joint 82 for secure engagement with the lower end of the leg 42, 62
of each oscillator. As shown in FIG. 14, the joint 82 is molded
around the lower end of the spring 80 to have a square stud 83
which engages into a corresponding square hole 46, 66 at the lower
end of the leg 42, 42 of each oscillator 40, 60 and is thereafter
welded thereto by the known ultrasonic welding. One of the legs of
each oscillator is longer than the other to have the hole 46, 66 at
a location immediately upwardly of the pivot hole 49, 69, as shown
in FIG. 15 while the other leg has the hole 46, 66 at its lower
end. As shown in FIGS. 16A and 16B, the joint 82 covers the entire
width of the lower end of the spring 80 to make the square
cross-section of the stud 83 as large as possible in order to
suspend the oscillator straight and therefore keep a precise
positioning of the permanent magnet relative to the pole ends of
the electromagnet, thereby assuring a stable oscillating movement
of the oscillators. As shown in FIG. 3, that the spring 80 has a
narrowed width at its lengthwise center to give a desired biasing
force, while having the upper and lower ends having a width greater
than the thickness of the leg of the oscillator so as to give the
above effect of precisely positioning the oscillators as well as to
give a secure connection of the spring to the oscillators. In this
connection, the springs 80 having the enlarged upper and lower
width are offset laterally from the oscillators but within the
thickness of the chassis 10 in order to keep the oscillators in
closely adjacent relation to each other, making the whole assembly
compact. For increased bonding strength to the joint 82, the spring
80 may be formed with a through-hole 84 for entrapping a portion of
the joint 82, as shown in FIGS. 17A and 18B Further, as shown in
FIGS. 18 and 19, the joint 82 may be formed at a portion
immediately opposite of the stud 83 with a bump 86 which is adapted
to be in contact with a horn of the ultrasonic welder for
concentrating the ultrasonic bonding pressure to the stud.
[0048] As shown in FIG. 20, the core 22 is made from a stack of the
metal plates to have horizontal extensions 25 extending
longitudinally away from the poles 23. The extensions 25 are each
formed with a stator's mating surface 26 which is a flat horizontal
surface for abutment against a chassis's mating surface 12 also of
a flat horizontal surface at the lower end of the chassis 10.
Thereafter, the extensions 25 are welded to the chassis 10. Thus,
the core 22, i.e., the stator 20 forming the electromagnet can be
easily and accurately assembled to the chassis 10 to give the
precise magnetic gap between the poles 23 and the permanent magnets
44 and 64. Also formed on the extensions 25 adjacent the stator's
mating surface 26 are first stoppers 27 which engage with the lower
inner edges of the chassis 10, as seen from FIGS. 20 and 21, so as
to fix the stator 20 to the chassis 10 relative to the lengthwise
direction, i.e., the oscillating direction of the oscillators 40
and 60. Further, as shown in FIGS. 22 and 23, the extensions 25 may
be formed with second stoppers 28 which project from the stator's
mating surfaces 26 to engage with slits 14 respectively formed in
the lower inner edges of the chassis 10 so as to fix the stator 20
to the chassis 10 with respect to the lateral direction
perpendicular to the oscillating direction, facilitating to make
correct positioning of the stator to the chassis prior to the
welding.
[0049] As shown in FIGS. 24 and 25, each of the poles 23 of the
core 22 is fitted with a coil bobbin 30 of dielectric material for
holding the winding 24 therearound. The coil bobbin 30 is formed at
its upper end with a latch projection 31 which projects radially
inwardly for latching engagement with a corresponding notch 29
formed at the upper end of each pole 23 of the core 22. Thus, the
coil bobbin 30 can be easily assembled to the core 22.
[0050] FIG. 26 illustrates a modified actuator which is identical
to that explained hereinbefore except that the lower end of each
leaf spring 80 has a width equal to the thickness of the
corresponding one of the legs 42 and 62 of the first and second
oscillators 40 and 60. The leaf spring 80 has a width larger at the
upper end than at the lower end. The upper end of the leaf spring
80 is offset laterally from the upright axis of the corresponding
one of the legs 42 and 62 of the first and second oscillators,
while keeping the legs in closely adjacent relation.
* * * * *