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JP2011130350

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DESCRIPTION JP2011130350
An object of the present invention is to provide a "speaker" which can suppress the generation of
abnormal noise due to the deflection of a diaphragm and can prevent damage to a damper which
may be concerned when an excessive current is applied. A rectangular diaphragm 2 of a speaker
1 is provided with reinforcement ribs (for example, reinforcement ribs 8 to 11) extending along
the width direction of the diaphragm 2 at a position separated from a voice coil 3 by a
predetermined amount. The thickness of the reinforcing rib is set such that one side surface
thereof faces the magnetic circuit 6. For example, one side surface of the reinforcing rib 8 faces
one side surface of the yoke 12, and one side surface of the reinforcing rib 9 faces one side
surface of the yoke 14. Further, the distance d between the reinforcing rib and the magnetic
circuit 6 at the time of non-energization is set to a value smaller than the allowable value of the
amount of elastic displacement of the damper 4 along the longitudinal direction of the
diaphragm 2. [Selected figure] Figure 3
スピーカ
[0001]
The present invention relates to a speaker that vibrates a diaphragm by energizing a voice coil in
a magnetic gap, and more particularly to a speaker in which a voice coil is provided in the form
of a planar coil in the vicinity of an end of the diaphragm.
[0002]
In this type of speaker, a voice coil is provided in the form of a flat coil near the end of the
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diaphragm formed in a rectangular shape or the like, and this voice coil is arranged in a
predetermined direction along the plate surface of the diaphragm (longitudinal direction of the
diaphragm). By driving, the vibrating diaphragm is vibrated in the direction orthogonal to the
plate surface.
Both ends in the longitudinal direction of the diaphragm are supported by a frame via a damper
or the like, and a magnetic circuit including a magnet and a yoke is attached to the frame. The
voice coil is disposed in the magnetic gap of the magnetic circuit, and when a current (voice
signal) is applied, an electromagnetic driving force along the longitudinal direction of the
diaphragm acts on the voice coil. In addition, in this type of speaker, there is conventionally
known a technique of directly patterning a voice coil in the vicinity of an end portion of a
diaphragm by etching or the like in order to promote weight reduction and cost reduction (for
example, patent documents 1).
[0003]
FIG. 5 is an explanatory view showing the structure in the vicinity of the magnetic circuit in the
conventional speaker in a simplified manner. In the figure, the diaphragm 20 is made of a thin
flat plastic film or the like, and one end 20a of the diaphragm 20 is elastically supported by a
damper 21 made of a gel-like elastic body or the like. Is held by A voice coil 23 is provided in the
form of a planar coil in the vicinity of one end 20 a of the diaphragm 20, and both ends of the
voice coil 23 are connected to a terminal (not shown). The portion of the diaphragm 20 provided
with the voice coil 23 is disposed in the magnetic gaps G1 and G2 of the magnetic circuit 24. The
magnetic circuit 24 comprises a plurality of yokes 25, 26, 27 and a magnet 28, and magnetic
gaps G1, G2 are respectively formed between a plate-like yoke (plate) 25 and a pair of yokes 26,
27 sandwiching the magnet 28. It is done. The magnetic circuit 24 is held by the frame 22, and
the gap size (gap length) of the magnetic gaps G 1 and G 2 is defined by the gap holder 29.
[0004]
The direction of the magnetic field in the magnetic gaps G1 and G2 is the vertical direction in
FIG. 5, and when current is supplied to the voice coil 23 through the terminal portion, the voice
coil 23 is in the direction orthogonal to the sheet of FIG. An electromagnetic driving force along
the longitudinal direction (horizontal direction in FIG. 5) of the diaphragm 20 acts on the
extended portion. As a result, the curved substantially central portion (not shown) of the
diaphragm 20 vibrates in a direction perpendicular to the plate surface to generate a sound
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pressure.
[0005]
JP, 2009-194460, A
[0006]
By the way, in the conventional speaker described above, although the use of the thin flat
diaphragm 20 is advantageous for weight reduction and low power consumption, on the other
hand, the diaphragm driven at the time of energization Since 20 is easily bent in the width
direction, the possibility of the voice coil 23 disposed in the magnetic gaps G1 and G2 coming
into contact with the magnetic circuit 24 is increased, and an offensive noise (chattering noise) is
easily generated. There was a problem.
[0007]
Further, in the above-described conventional speaker, although the damper 21 is designed to be
elastically deformed following the vibration of the diaphragm 20, an excessive current is applied
for some reason and an excessive electromagnetic driving force is applied to the diaphragm 20.
Since the damper 21 is pulled by the diaphragm 20 beyond the allowable limit of elastic
deformation when there is an action, there is a risk that the damper 21 is damaged and the
diaphragm 20 does not operate normally.
[0008]
The present invention has been made in view of the circumstances of the prior art as described
above, and its object is to suppress the generation of abnormal noise due to the deflection of the
diaphragm and to be concerned when an excessive current is applied. An object of the present
invention is to provide a speaker capable of preventing damage to the damper in advance.
[0009]
In order to achieve the above object, according to the present invention, there is provided a
rectangular diaphragm in which a voice coil is provided in the form of a planar coil near at least
one end, and a frame supporting both longitudinal ends of the diaphragm. And a damper
interposed between the frame and at least one end of the diaphragm, and a magnetic circuit
attached to the frame with a magnetic gap in which the voice coil is disposed, the voice In the
speaker for vibrating the diaphragm by energizing the coil, the diaphragm is provided with a
reinforcing rib extending along the short direction of the diaphragm at a position separated from
the voice coil, and the reinforcing rib and the magnetic when not energized The distance between
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the circuit and the circuit was set to a value smaller than the allowable value of the amount of
elastic displacement of the damper along the longitudinal direction of the diaphragm.
[0010]
Since the reinforcing rib attached to the diaphragm extends along the width direction (short side
direction) of the diaphragm in the vicinity of the voice coil in the speaker configured in this
manner, the width direction of the diaphragm within the magnetic gap There is no risk of
bending.
Also, even if an excessive current is applied and an excessive electromagnetic driving force acts
on the diaphragm, the reinforcing rib abuts on the magnetic circuit before the damper exceeds
the allowable limit of elastic deformation, thereby causing excessive movement of the diaphragm.
Because the regulation is performed, damage to the damper can be prevented in advance.
[0011]
In the above configuration, when the reinforcing ribs are provided at two positions facing each
other across the voice coil, reciprocation of the diaphragm can be reliably restricted by each
reinforcing rib when an excessive current is applied. preferable.
[0012]
Further, in the above configuration, the reinforcing ribs may be provided only on one side of the
diaphragm, but if the reinforcing ribs are provided on both the front and back sides of the
diaphragm, the reinforcing ribs on both sides cause excessive vibration of the diaphragm.
Movement can be regulated more reliably.
[0013]
Further, in the above configuration, the reinforcing rib can be appropriately selected from light,
hard and inexpensive materials. Among them, a reinforcing rib made of carbon resin is
particularly preferable.
[0014]
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In the speaker according to the present invention, the reinforcing rib attached to the diaphragm
extends along the width direction of the diaphragm in the vicinity of the voice coil, and the
reinforcing rib functions as a cross beam reinforcing the diaphragm, so There is no possibility
that the diaphragm will be bent in the width direction, so that the generation of abnormal noise
due to the bending of the diaphragm can be suppressed.
Furthermore, even if an excessive current is applied, the reinforcing rib abuts on the magnetic
circuit before the damper exceeds the allowable limit of elastic deformation to restrict excessive
movement of the diaphragm, thereby preventing damage to the damper in advance. Can.
[0015]
It is an explanatory view simplifying and showing the section structure of the speaker concerning
the example of an embodiment of the present invention.
It is a perspective view of the diaphragm used by the speaker of FIG.
It is a principal part enlarged view of FIG.
It is a top view corresponding to FIG.
It is explanatory drawing which simplifies and shows the structure of the magnetic circuit vicinity
in the conventional speaker.
[0016]
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to
4.
As shown in these figures, the speaker 1 according to this embodiment includes a rectangular
diaphragm 2 in which a voice coil 3 is provided in the form of a planar coil near one end 2a, and
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a longitudinal direction of the diaphragm 2 A magnetic circuit 6 attached to the frame 5 with the
frame 5 elastically supporting the one end 2a via the damper 4 and fixedly supporting the other
end 2b, and the magnetic gaps G1 and G2 And the gap holder 7 for defining the gap size (gap
length) of the magnetic gaps G1 and G2, and the band-like reinforcing ribs 8, 9, 10 and 11
dispersed on both the front and back sides of the diaphragm 2. Is configured.
[0017]
The diaphragm 2 is made of a thin flat plastic film or the like.
The diaphragm 2 is supported by the frame 5 so as to extend from the one end 2 a to a
substantially central portion in the longitudinal direction while maintaining a flat surface, and a
portion of the diaphragm 2 provided with the voice coil 3 is a magnetic circuit 6. Are disposed in
the magnetic gaps G1, G2. When the voice coil 3 is driven in the direction of arrow A by the
magnetic circuit 6, the substantially central portion of the diaphragm 2 vibrates in a direction
perpendicular to the plate surface and is curved. At this time, the damper 4 supporting the one
end portion 2 a of the diaphragm 2 elastically deforms following the movement of the diaphragm
2. The damper 4 is made of, for example, a gel-like elastic body or an oil damper, and the frame 5
holds the damper 4. The frame 5 is formed by molding a synthetic resin or the like.
[0018]
As shown in FIG. 2, the voice coil 3 is formed by etching or the like in a frame-like region in the
vicinity of one end 2 a of the diaphragm 2, and both ends of the voice coil 3 are connected to
terminal portions not shown. The voice coil 3 has a first strip 3a extending along the widthwise
direction of the diaphragm 2 (the width direction shown by the arrow B) and an arrow A
direction (longitudinal length of the diaphragm 2) orthogonal to the first strip 3a. And the second
strip 3b extending along the direction is patterned as a continuous strip-shaped conductor. The
first band-shaped portion 3a is an effective portion contributing to the vibration of the
diaphragm 2, and is formed to be longer than the second band-shaped portion 3b. The second
strip portion 3 b is an ineffective portion that does not contribute to the vibration of the
diaphragm 2, and is located on both sides of the diaphragm 2.
[0019]
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The reinforcing ribs 8 to 11 are formed by printing and curing paste-like carbon resin on the
diaphragm 2, but the reinforcing ribs may be formed using other materials (for example,
aluminum foil, paper, etc.). Each of the reinforcing ribs 8 to 11 extends in the shape of a band
having a length substantially equal to the width dimension of the diaphragm 2 along the arrow B
direction. These reinforcing ribs 8 to 11 are relatively thin and lightweight but hard and difficult
to deform, and thus function as a cross beam that reinforces the diaphragm 2. As shown in FIGS.
3 and 4, one reinforcing rib 8 is provided at a position separated from the voice coil 3 by a
predetermined amount on one side of the one end portion 2 a of the diaphragm 2, and another
reinforcing rib 9 is the diaphragm 2. It is provided in the position corresponding to the
reinforcement rib 8 in the other surface of the one end part 2a. The pair of reinforcing ribs 8 and
9 is formed as a slightly wide band, and one side surface of the reinforcing rib 8 can be in
contact with one side surface of the yoke (plate) 12 of the magnetic circuit 6. One side surface
can be in contact with one side surface of the yoke 14 of the magnetic circuit 6. Further, one of
the remaining two reinforcing ribs 10 is provided on one side of the diaphragm 2 at a position
opposite to the reinforcing rib 8 as viewed from the voice coil 3, and the other reinforcing rib 11
is of the diaphragm 2. It is provided at a position corresponding to the reinforcing rib 10 on the
other side. The pair of reinforcing ribs 10 and 11 is formed as a somewhat narrow band, and one
side surface of the reinforcing rib 10 can contact the other side surface of the yoke 12 of the
magnetic circuit 6, and one side surface of the reinforcing rib 11 Can be in contact with one side
surface of the yoke 13 of the magnetic circuit 6. The reinforcing ribs 8 to 11 are all formed to
have the same thickness, where Tr is the thickness, Tf is the thickness of the diaphragm 2 and Tg
is the gap length of the magnetic gaps G1 and G2, (2Tr + Tf)> Since the relational expression Tg
is established, the value of Tr is larger than the value of {(Tg−Tf) / 2}.
[0020]
As shown in FIG. 3, when not energized, the intervals between the reinforcing ribs 8 to 11 and
the magnetic circuit 6 are all set to the same value d. That is, the reinforcing rib 8 is separated
from one side surface of the yoke 12 by the dimension d, and the reinforcing rib 10 is separated
from the other side surface of the yoke 12 by the size d. Further, the reinforcing rib 9 is
separated from one side surface of the yoke 14 by a dimension d, and the reinforcing rib 11 is
separated from one side surface of the yoke 13 by a dimension d. In this embodiment, a value
slightly smaller than the allowable value of the amount of elastic displacement of the damper 4
along the direction of the arrow A (longitudinal direction of the diaphragm 2) is selected as the
magnitude of the value d. When the elastic deformation of the diaphragm 4 is large, the
reinforcing ribs 8 to 11 abut against the magnetic circuit 6 to restrict the vibration of the
diaphragm 2, thereby preventing the damper 4 from being elastically deformed beyond the
allowable limit.
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[0021]
As shown in FIG. 1, the magnetic circuit 6 is configured by combining a plurality of yokes 12, 13,
14 and a magnet 15, and a plate-like yoke (plate) with a pair of yokes 13, 14 sandwiching the
magnet 15. The magnetic gaps G1 and G2 are respectively formed between them. The direction
of the magnetic field in the magnetic gaps G1 and G2 is almost the same as the thickness
direction of the diaphragm 2, but the directions of the magnetic fields in the magnetic gap G1
and the magnetic gap G2 are opposite. The upper first band-shaped portion 3a in FIG. 2 is
disposed in the magnetic gap G1, and the lower first band-shaped portion 3a in the figure is
disposed in the magnetic gap G2.
[0022]
Then, when current is supplied to the voice coil 3 through the terminal portion, reverse current
flows in the upper first strip portion 3a and the lower first strip portion 3a in FIG. An
electromagnetic driving force in the same direction also acts on the one strip portion 3a.
According to Fleming's left-hand rule, the direction of the electromagnetic driving force is in the
direction of arrow A, so the diaphragm 2 is driven along the longitudinal direction. As a result,
the substantially central portion of the diaphragm 2 vibrates in the direction orthogonal to the
plate surface to generate a sound pressure.
[0023]
Thus, in the speaker 1 according to this embodiment, the reinforcing ribs 8 to 11 attached to the
diaphragm 2 extend along the width direction (arrow B direction) of the diaphragm 2 in the
vicinity of the voice coil 3, Since these reinforcing ribs 8 to 11 function as cross beams that
reinforce the diaphragm 2, there is no possibility that the diaphragm 2 will be bent in the width
direction in the magnetic gaps G1, G2. Therefore, the speaker 1 can effectively suppress the
generation of abnormal noise caused by the deflection of the diaphragm 2.
[0024]
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In the speaker 1 according to the present embodiment, even if an excessive current is applied
and an excessive electromagnetic driving force acts on the diaphragm 2, the reinforcing ribs 8 to
8 are used before the damper 4 exceeds the allowable limit of elastic deformation. Since 11 abuts
on the side surfaces (side surfaces of the yokes 12 to 14) of the magnetic circuit 6 to restrict
excessive movement of the diaphragm 2, damage to the damper 4 can be prevented in advance.
Therefore, the speaker 1 is not easily broken even if an excessive current is applied, and the
reliability is increased.
[0025]
In the embodiment described above, a case where a total of four reinforcing ribs 8 to 11 are
dispersedly provided on both the front and back surfaces of the diaphragm 2 has been described.
However, a configuration in which reinforcing ribs are provided on only one surface of the
diaphragm 2 For example, even if only the reinforcing ribs 8 and 10 are provided, substantially
the same effect as that of the above embodiment can be obtained.
[0026]
Further, although in the above-described embodiment, the reinforcing ribs are provided at two
places of the diaphragm 2 facing each other across the voice coil 3, the reinforcing ribs may be
provided only at one of the sites. Deflection in the width direction of the diaphragm 2 can be
effectively prevented.
[0027]
In the embodiment described above, the speaker in which the voice coil 3 is provided only at one
end 2a of the diaphragm 2 has been described. However, voice coils are provided at both ends 2a
and 2b in the longitudinal direction of the diaphragm 2 A speaker having a configuration in
which each voice coil is individually disposed in the magnetic gap of two magnetic circuits
attached to both ends of 5 and each of the both ends 2a and 2b of the diaphragm 2 is elastically
supported by a damper In this case, it is preferable to provide reinforcing ribs at both ends 2a
and 2b of the diaphragm 2.
[0028]
The width dimension and the length of the reinforcing rib can be appropriately selected
according to the forming position of the reinforcing rib, the size of the diaphragm 2, the material
and the like.
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Further, the shape of the frame 5 and the configuration of the magnetic circuit 6 are not limited
to the above embodiment.
[0029]
Reference Signs List 1 speaker 2 diaphragm 3 voice coil 4 damper 5 frame 6 magnetic circuit 8
to 11 reinforcement rib 12 to 14 yoke 15 magnet G1, G2 magnetic gap
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