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JP2004088646

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DESCRIPTION JP2004088646
An electro-acoustic transducer with improved impact resistance is provided. An electro-acoustic
transducer (1) has a cylindrical surface direction displacement restriction portion (14) extending
from an upper surface portion of an upper case (11) to an outer periphery of an end face of a
magnetic piece (47). The surface direction displacement restricting portion 14 restricts the
displacement of the magnetic piece 47 in the surface direction when an impact due to a drop or
the like is applied to the electroacoustic transducer 1. Thereby, since the diaphragm 46 can be
prevented from being buckled, the impact resistance of the electroacoustic transducer 1 can be
enhanced. [Selected figure] Figure 2
Electro-acoustic transducer
TECHNICAL FIELD [0001] The present invention relates to an electroacoustic transducer. [0002]
A conventional electro-acoustic transducer accommodates a diaphragm in which a plate-like
magnetic piece serving as an additional mass is joined to one surface in a cylindrical case with a
resonance space separated. Furthermore, an iron core is accommodated on the other surface side
of the diaphragm, and a drive source in which a coil and a ring-shaped magnet are disposed in
order on the outer peripheral side of the iron core is accommodated. Then, by applying an
alternating voltage or pulse voltage to both ends of the coil, the diaphragm is vibrated in the
direction perpendicular to the plate surface, and the sound is emitted from the sound emission
port provided on the wall surface of the case. [0003] However, in the conventional electroacoustic transducer, when an impact is applied by dropping or the like, a direction in which the
magnetic piece crosses the original vibration direction of the diaphragm (for example, a
perpendicular direction) ) May cause the diaphragm to buckle, which may change the acoustic
characteristics of the electroacoustic transducer or cause a failure, and further improvement of
the impact resistance is desired. The The present invention has been made to solve the above-
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mentioned problems, and it is an object of the present invention to provide an electroacoustic
transducer with improved impact resistance. In order to solve the above problems, in the electroacoustic transducer according to the present invention, a diaphragm in which a plate-like
magnetic piece is joined to one surface is perpendicular to the plate surface. An electro-acoustic
transducer that emits vibration by vibrating in one direction is characterized in that it comprises
regulating means for regulating the displacement of the magnetic piece in the direction
intersecting the direction of the vibration. According to the electro-acoustic transducer, the platelike magnetic piece joined to one surface of the diaphragm intersects the surface direction of the
diaphragm, ie, the vibration direction of the diaphragm during operation of the electro-acoustic
transducer. Control means for restricting displacement in the direction (e.g., the vertical
direction). Therefore, even if an impact is applied to this electroacoustic transducer, the buckling
of the diaphragm can be prevented, so that the impact resistance can be enhanced. In the electroacoustic transducer according to the present invention, preferably, the restriction means is
disposed at a predetermined interval so as to surround the outer periphery of the end face of the
magnetic piece. . According to the present invention, the displacement of the magnetic piece can
be effectively restricted by arranging the restriction means at a predetermined interval so as to
surround the outer periphery of the end face of the magnetic piece. Therefore, even if an impact
is applied to this electroacoustic transducer, as a result of being able to prevent the buckling of
the diaphragm, its impact resistance can be enhanced.
The electro-acoustic transducer according to the present invention further comprises a case for
accommodating the diaphragm to which the magnetic piece is joined, and the regulation means is
provided on the one side of the diaphragm. It may be characterized in that it comprises a
plurality of projections which extend from the inner wall and which are disposed to surround the
outer periphery of the end face of the magnetic piece. According to the present invention, a
plurality of projections extending from the case inner wall on one side of the diaphragm, ie, the
resonance space side, and surrounding the outer periphery of the end face of the magnetic piece
are used as the restricting means. Thereby, the above-mentioned displacement of a magnetic
piece can be regulated, reducing the rate for which this convex part occupies to resonance space.
As a result, even if an impact is applied to the electroacoustic transducer, it is possible to prevent
the buckling of the diaphragm, and thus the impact resistance can be enhanced. The electroacoustic transducer according to the present invention further comprises a case for housing the
diaphragm to which the magnetic piece is joined, the magnetic piece being in the shape of a disc,
and the restriction means is the magnetic member. The end face of the magnetic piece is
surrounded by the inner peripheral surface of the tip of the sound emitting cylinder having a tip
with an inner diameter larger than the outer diameter of the piece and extending from the inner
wall of the case on one surface of the diaphragm. It may be characterized by According to the
present invention, the sound output tube extending from the one surface side of the diaphragm,
that is, the inner wall of the case on the side of the resonance space also serves as the control
means. The tip end portion of the sound emitting tube has an inner diameter larger than the
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outer diameter of the disk-shaped magnetic piece, and the tip portion surrounds the outer
periphery of the end face of the magnetic piece, so that the above-described displacement of the
magnetic piece can be restricted. Therefore, even if an impact is applied to this electroacoustic
transducer, as a result of being able to prevent the buckling of the diaphragm, its impact
resistance can be enhanced. The electro-acoustic transducer according to the present invention
further comprises a case for housing the diaphragm to which the magnetic piece is joined, and
the magnetic piece is on the opposite side to the surface joined to the diaphragm. The control
means has a tip portion having an outer diameter smaller than the inner diameter of the recess,
and the release means extends from the inner wall of the case on one side of the diaphragm. The
tip end of the sound cylinder may be inserted into the recess. According to the present invention,
the magnetic piece is formed with a circular recess at the center, and the tip outer diameter of
the sound emitting tube extending from the inner wall of the case on the resonance space side is
smaller than the inner diameter of the recess, By inserting it into the recess, it becomes a
regulating means. That is, the outer peripheral surface of the tip end portion of the sound output
tube faces the inner peripheral surface of the recess formed in the magnetic piece.
Since the above-mentioned displacement of the magnetic piece is restricted by this, even if an
impact is applied to this electroacoustic transducer, it is possible to prevent the buckling of the
diaphragm, and as a result, its impact resistance can be enhanced. Further, in the electro-acoustic
transducer according to the present invention, the magnetic piece has a disk shape, and the
restriction means has an inner diameter larger than the outer diameter of the magnetic piece,
and It may be characterized by being formed of a ring-shaped member disposed with the
circumferential surfaces facing each other. According to the present invention, the outer
periphery of the end face of the magnetic piece is surrounded by the inner peripheral surface of
the ring-shaped member having an inner diameter larger than the outer diameter of the diskshaped magnetic piece. Therefore, the above-mentioned displacement of the magnetic piece can
be regulated by this ring-shaped member. As a result, even if an impact is applied to the
electroacoustic transducer, it is possible to prevent the buckling of the diaphragm, and thus the
impact resistance can be enhanced. In the electro-acoustic transducer according to the present
invention, the ring-shaped member is preferably made of a magnetic material. According to the
present invention, the ring-shaped member further forms the auxiliary magnetic path, so that the
magnetic flux based on the voltage applied to the coil can efficiently flow into the magnetic piece.
BEST MODE FOR CARRYING OUT THE INVENTION An electroacoustic transducer according to an
embodiment of the present invention will be described below. In the following description of the
embodiment, in order to facilitate understanding of the description, the same constituent
elements in the drawings are denoted by the same reference numerals as much as possible, and
redundant description will be omitted. Also, the dimensional ratios in the drawings do not
necessarily match those in the description. First Embodiment First, an electro-acoustic transducer
1 according to a first embodiment of the present invention will be described. FIG. 1 is a plan view
of the upper case 11 provided in the electroacoustic transducer 1 according to the first
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embodiment as viewed from the open end thereof. FIG. 2 is a cross-sectional view showing a
cross-sectional structure of the electroacoustic transducer 1 together with a cross-section taken
along line II-II of the upper case 11 shown in FIG. As shown in FIG. 1 and FIG. 2, this
electroacoustic transducer 1 has an upper case 11 and a lower case 21 made of thermoplastic
resin, and by using ultrasonic welding technology, the upper side The case 11 and the lower case
21 are joined. The upper case 11 has a cylindrical shape and has an upper surface at one end. A
sound emission port 12 is formed on the upper surface portion, and a sound emission tube 13 is
provided continuously to the sound emission port 12.
The base 31, the iron core 32, the bobbin 33, the coil 34, the magnet 39, and the vibration unit
45 are accommodated in an internal space formed by the upper case 11 and the lower case 21. A
base 31 is fixed to the above-mentioned inner space side of the lower case 21, and a substantially
cylindrical iron core 32 is crimped by the base 31 and the lower case 21. The bottom of the
bobbin 33 is fixed to the upper surface of the base 31, and the extended portion thereof is placed
along the outer periphery of the iron core 32. A conducting wire is wound around the outer
periphery of the bobbin 33 to form a coil 34. Both ends of the coil are connected to pins (not
shown) serving as electrical contacts with the outside. The magnet 39 is an annular plastic
magnet, the bottom surface of which is in contact with the base 31 and the outer peripheral
surface of which is in contact with the inner peripheral surface of the upper case 11 and is
arranged at a predetermined distance from the outer periphery of the coil 34. ing. A vibrating
portion 45 is fixed to the upper surface of the magnet 39. The vibrating portion 45 is provided
with a thin-film disk-shaped vibrating plate 46 made of iron material, and a disk-shaped magnetic
as an additional mass at the center of the upper surface. The piece 47 is fixed. Furthermore, from
the inner wall of the upper surface portion of the upper case 11, three cylindrical surface
direction displacement regulating portions (regulating means) 14 extend to a position facing the
end face of the magnetic piece 47, and the end face of the magnetic piece 47 It is provided to
surround the outer periphery. Further, at the tip end of the sound output tube 13, three
protrusion-like vibration direction displacement regulation portions 15 are provided at equal
intervals. The operation of the electroacoustic transducer 1 will now be described. In the
electroacoustic transducer 1, the vibrating portion 45 is attracted to the iron core 32 side by the
static magnetic field of the magnet 39. In this state, when an AC voltage or pulse voltage is
applied to the conductors at both ends of the coil 34, a signal current flows through the coil 34,
and an oscillating magnetic field corresponding to this signal current is generated at the tip of
the iron core 32. Then, when the vibrating portion 45 vibrates in a direction perpendicular to the
surface by the vibrating magnetic field, the surrounding air is vibrated, and this vibration is
amplified in the resonance space 50 and emitted from the sound emission port 12 to the outside.
In the electro-acoustic transducer 1 having such a configuration, when the electro-acoustic
transducer 1 receives an impact due to a drop or the like, the magnetic piece 47 moves in the
plane direction of the electro-acoustic transducer 1. That is, while the electroacoustic transducer
1 is in operation, the displacement of the magnetic piece 47 in the direction (for example, the
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perpendicular direction) intersecting the direction in which the diaphragm 46 originally vibrates
is restricted.
As a result, it is possible to prevent the diaphragm 46 from being buckled by the weight of the
magnetic piece 47, and as a result, the impact resistance of the electroacoustic transducer 1 can
be enhanced. Similarly, when the electroacoustic transducer 1 receives an impact due to a drop
or the like, the vibration direction displacement restricting portion 15 excessively moves the
magnetic piece 47 in the direction perpendicular to the surface, that is, the electroacoustic
transducer 1 regulates excessive displacement of the magnetic piece 47 in the direction in which
the diaphragm 46 vibrates during operation. As a result, even if an impact is applied to the
electroacoustic transducer 1, the influence of deformation or the like given to the diaphragm 46
can be prevented, so that the impact resistance can be enhanced. Furthermore, while having such
an effect, since the surface direction displacement regulating portion 14 is formed into a
cylindrical shape with a small volume as described above, the volume occupied by the surface
direction displacement regulating portion 14 in the resonance space 50 can be reduced. . Here,
FIG. 3 shows changes in acoustic characteristics before and after the shock due to the drop is
applied to the electro-acoustic transducer 1. Further, for reference, FIG. 4 shows changes in
acoustic characteristics before and after an impact due to a drop is applied to the electroacoustic
transducer which does not have the surface direction displacement restricting portion 14. The
characteristics shown in FIGS. 3 and 4 are based on data obtained by measuring the sound
pressure level by applying a voltage of 5 [V] and a 50% square wave to the electroacoustic
transducer while changing the frequency. It is. Also, the characteristics shown by the solid line
are based on the data for the electro-acoustic transducer before falling, and the characteristics
shown by the dotted line are based on the data for the electro-acoustic transducer after falling.
As clearly shown in FIGS. 3 and 4 by referring to the characteristics around 700 [Hz] which is the
peak frequency of the electro-acoustic transducer used in the evaluation, the electro-acoustic
transducer 1 according to this embodiment is By providing the surface direction displacement
restricting portion 14, the change in acoustic characteristics before and after the drop is small.
On the other hand, in the electro-acoustic transducer which does not have the surface direction
displacement restriction portion 14, the acoustic characteristics are largely changed before and
after the fall. From the above results, it is clear that the electro-acoustic transducer 1 according
to the present embodiment is excellent in impact resistance by the surface direction displacement
restricting portion 14. Although the electro-acoustic transducer 1 according to the first
embodiment of the present invention has been described above, the present invention can be
variously modified without being limited to the above-described embodiment. For example,
although the number of the plane direction displacement restricting portions 14 is three in the
above embodiment, the number is larger than this number, and arranged so as to restrict the
displacement of the magnetic pieces 47 in the plane direction. Therefore, the number is not
limited.
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In the first embodiment, the shape of the surface direction displacement regulating portion 14 is
a cylindrical shape, but this shape can be changed, for example, as follows. FIG. 5 is a plan view
of the upper case 11 of the electroacoustic transducer 1 according to the modified embodiment
as viewed from the open end thereof. 6 is a cross-sectional view showing a cross-sectional
structure of the electro-acoustic transducer 1, together with a cross-section taken along line VI-VI
of the upper case 11 shown in FIG. In the electroacoustic transducer 1 shown in FIGS. 5 and 6,
the surface direction displacement regulating portion 14 is a member having a substantially
rectangular cross section extending from the inner wall of the upper surface portion of the upper
case 11, and the portion facing the end face of the magnetic piece 47 is a curved surface. It has a
shape. Then, three surface direction displacement regulating portions 14 are provided so as to
surround the magnetic piece 47. Also by the surface direction displacement restricting portion
14 having such a shape, it is possible to restrict the displacement of the magnetic piece 47 in the
surface direction due to an impact or the like and to improve the impact resistance of the
electroacoustic transducer 1. Further, although the magnetic piece 47 has a disk shape, this
shape may be a flat plate having various planar shapes such as a triangle and a star shape, for
example. In this case, the displacement of the magnetic piece 47 in the surface direction can be
restricted by changing the position of the surface direction displacement regulating portion 14
so as to surround the outer periphery of the end face of the magnetic piece 47 according to the
shape of the magnetic piece 47. . Second Embodiment Next, an electroacoustic transducer 1
according to a second embodiment of the present invention will be described. In the following
description, the description of the portions common to the electroacoustic transducer 1
described in the first embodiment will be omitted. FIG. 7 is a plan view of the upper case 11
provided in the electroacoustic transducer 1 according to the second embodiment as viewed
from the open end thereof. FIG. 8 is a cross-sectional view showing the VIII-VIII cross section of
the upper case 11 in FIG. 7 together with the cross-sectional structure of the electroacoustic
transducer 1. As shown in FIG. As shown in FIGS. 7 and 8, in the electroacoustic transducer 1
according to the second embodiment, the magnetic piece 47 has a substantially disc shape and is
opposite to the surface joined to the diaphragm 46. The ridge portion 48 is provided at the
periphery of the face of Further, a sound outlet 12 is provided at the center of the upper surface
portion of the upper case 11, and the tip end of the sound emitting cylinder 13 provided
continuously to the sound outlet 12 faces the end face of the flange portion 48 of the magnetic
piece 47. Extend to the desired position. The inner diameter of the tip of the sound emitting tube
13 is larger than the outer diameter of the collar 48, and the inner peripheral surface of the tip is
disposed as the surface direction displacement restriction portion 14 so as to surround the end
face of the collar 48 . By providing the surface direction displacement restricting portion 14 in
this manner, it is possible to restrict the displacement of the magnetic piece 47 in the surface
direction due to an impact or the like.
As a result, even if an impact is applied to the electroacoustic transducer 1, the diaphragm 46
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can be prevented from buckling, so that the impact resistance of the electroacoustic transducer 1
can be enhanced. Further, the inner diameter of the body portion of the sound output tube 13 is
smaller than the inner diameter of the tip portion, and the surface formed by the difference in the
inner diameter serves as the vibration direction displacement restricting portion 15 so as to face
the upper surface of the flange portion 48 Do. As a result, excessive displacement of the
magnetic piece 47 in the direction perpendicular to the plate surface due to impact or the like
can be restricted. As a result, it is possible to prevent the influence of deformation or the like
given to the diaphragm 46 by the impact. Thus, in the electro-acoustic transducer 1 according to
the second embodiment, it is possible to improve the impact resistance due to dropping or the
like, and the sound output cylinder 13 doubles as the surface direction displacement restricting
portion 14 and the vibration direction displacement restricting portion 15. Therefore, as in the
electroacoustic transducer 1 shown in the first embodiment, it is not necessary to provide a
separate convex portion on the inner wall of the upper surface portion of the upper case 11 as
the surface direction displacement restricting portion 14 and the vibration direction
displacement restricting portion 15 . As a configuration in which the sound output tube 13
doubles as the surface direction displacement restricting portion 14 and the vibration direction
displacement restricting portion 15, for example, the following modification may be applied. FIG.
9 is a plan view of the upper case 11 of the electroacoustic transducer 1 according to the
modified embodiment as viewed from the open end thereof. FIG. 10 is a cross-sectional view
showing a cross-sectional structure of the electroacoustic transducer 1 together with an X-X
cross section of the upper case 11 shown in FIG. In the electroacoustic transducer 1 shown in
FIG. 9 and FIG. 10, the magnetic piece 47 has a substantially disc shape, and has a ridge portion
48 on the periphery of the surface opposite to the surface joined to the diaphragm 46. Thus, a
recess is formed at the center of the magnetic piece 47. Further, a sound output port 12 is
provided at the center of the upper surface portion of the upper case 11, and a sound output
tube 13 is provided continuously to the sound output port 12. The outer diameter of the tip of
the sound release tube 13 is smaller than the inner diameter of the recess of the magnetic piece
47, and the tip extends to a position where the tip is inserted into the recess of the magnetic
piece 47. Then, the outer peripheral surface of the tip end portion of the sound output tube 13
serves as the surface direction displacement restriction portion 14 and faces the inner peripheral
surface of the recess of the magnetic piece 47. Thus, displacement of the magnetic piece 47 in
the surface direction due to an impact or the like can be restricted. Further, the outer diameter of
the sound release cylinder 13 is larger than the outer diameter of the tip end portion, and the
surface formed by the difference of the outer diameter serves as the vibration direction
displacement restricting portion 15 so as to face the upper surface of the flange portion 48 Do.
As a result, excessive displacement of the magnetic piece 47 in the direction perpendicular to the
plate surface due to impact or the like can be restricted.
Thus, the impact resistance of the electroacoustic transducer 1 can be enhanced also by forming
a recess in the magnetic piece 47 and inserting the tip of the sound output tube 13 into the
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recess. Third Embodiment An electro-acoustic transducer 1 according to a third embodiment of
the present invention will be described. In the following description, the description of the
portions common to the electroacoustic transducer 1 described in the first embodiment will be
omitted. FIG. 11 is a cross-sectional view of the electro-acoustic transducer 1 according to the
third embodiment. As shown in FIG. 11, in the electroacoustic transducer 1 according to the third
embodiment, the magnetic piece 47 has a substantially disc shape, and a ring-shaped member
having an inner diameter larger than the outer diameter of the magnetic piece 47 is surface
direction The displacement restricting portion 14 is disposed to surround the outer periphery of
the end face of the magnetic piece 47. The end surface of the surface direction displacement
restricting portion 14 is in contact with the side inner wall surface of the upper case 11, and the
peripheral portion of one surface is fixed to the magnet 39. As described above, also by the
surface direction displacement regulating portion 14 of the ring-shaped member, displacement of
the magnetic piece 47 in the surface direction due to an impact or the like can be regulated. As a
result, it is possible to prevent the buckling of the diaphragm 46 due to impact or the like, and to
improve the impact resistance of the electroacoustic transducer 1. In the electro-acoustic
transducer 1 according to the third embodiment, it is more preferable that the ring-shaped
member made of a magnetic material be a surface direction displacement restricting portion 14.
In this case, the surface direction displacement restricting portion 14 has the effect of being able
to restrict the displacement of the magnetic piece 47 in the surface direction as described above,
and the surface direction displacement restricting portion 14 which is a ring-shaped magnet
Since the auxiliary magnetic path is formed, the magnetic flux based on the voltage applied to the
coil 34 can efficiently flow into the magnetic piece 47. According to the present invention, the
regulation means is disposed at a predetermined interval so as to surround the outer periphery
of the end face of the plate-like magnetic piece joined to one surface of the diaphragm. . The
restricting means restricts the displacement of the magnetic piece in a direction (for example, the
perpendicular direction) intersecting the original vibration direction perpendicular to the plate
surface of the diaphragm, so even if an impact is applied to the electroacoustic transducer As a
result, it is possible to prevent the buckling of the diaphragm and to improve its impact
resistance. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of an upper case of an
electroacoustic transducer according to a first embodiment. FIG. 2 is a cross-sectional view of the
electro-acoustic transducer according to the first embodiment. FIG. 3 is a graph showing acoustic
characteristics before and after a drop test of the electro-acoustic transducer according to the
embodiment.
FIG. 4 is a graph showing acoustic characteristics before and after a drop test of an
electroacoustic transducer which does not have a surface direction displacement restriction part.
FIG. 5 is a plan view of an upper case of the electro-acoustic transducer according to a
modification of the first embodiment. FIG. 6 is a cross-sectional view of an electro-acoustic
transducer according to a modification of the first embodiment. FIG. 7 is a plan view of the upper
case of the electro-acoustic transducer according to the second embodiment. FIG. 8 is a cross-
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sectional view of an electro-acoustic transducer according to a second embodiment. FIG. 9 is a
plan view of an upper case of an electroacoustic transducer according to a modification of the
second embodiment. FIG. 10 is a cross-sectional view of an electro-acoustic transducer according
to a modification of the second embodiment. FIG. 11 is a cross-sectional view of an electroacoustic transducer according to a third embodiment. [Description of the code] 1 ... electroacoustic transducer, 11 ... upper case, 12 ... sound emission port, 13 ... sound emission cylinder,
14 ... surface direction displacement regulation section, 15 ... vibration direction displacement
regulation section, 21 ... lower case , 31: base, 32: iron core, 33: bobbin, 34: coil, 39: magnet, 45:
vibrating portion, 46: diaphragm, 47: magnetic piece, 48: ridge portion, 50: resonance space
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