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JP2011172157

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DESCRIPTION JP2011172157
An electromagnetic transducer with excellent performance is obtained by oscillating a diaphragm
with a dual support structure with a small number of parts. An electromagnetic converter
includes: permanent magnets (13a, 13b), a lower frame (12) for fixing one of pole faces of the
permanent magnets (13a, 13b), an upper frame (11) having an opening (11a) at the other
magnetic pole It has a magnetic circuit consisting of plates 14a and 14b fixed to the other
magnetic pole surface, and a diaphragm 15 in which a voice coil pattern 15g is disposed on side
surfaces 15b and 15c in the longitudinal direction and a top surface 15a. The protruding
portions 15i and 15j are connected between the side surfaces 15b and 15c. The periphery of the
top surface 15 a of the diaphragm 15 is joined to the periphery of the opening 11 a of the upper
frame 11 via the upper gasket 16. Further, the flange portion 15 f at the periphery of the four
side surfaces of the diaphragm 15 is joined to the inner peripheral surface of the upper frame
11, that is, the inside of the magnetic circuit via the lower gasket 18. [Selected figure] Figure 1
Electromagnetic converter
[0001]
The present invention relates to an electromagnetic transducer that performs sound
reproduction from an audio signal by combining a permanent magnet and a diaphragm.
[0002]
As a conventional speaker of the structure which integrated the diaphragm and the voice coil
pattern, there exist a speaker of the planar sound conversion apparatus of patent document 1, for
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example, and patent document 2. FIG.
In the flat acoustic transducer of Patent Document 1, a spiral voice coil pattern is formed on a
sheet made of polyimide of a thermosetting resin or polyethylene terephthalate (PET) of a
thermoplastic resin or a liquid crystal polymer, and both ends are bent. The diaphragm has a Ushaped cross section. The top surface of the diaphragm and the frame are joined by elastic edges
so that the voice coil patterns on both ends of the diaphragm are held so as to come to the
magnetic flux generating portion of the magnetic circuit. For this reason, even if the amplitude of
the diaphragm increases, the vertical displacement width of the voice coil pattern can be
contained in the magnetic flux generation portion.
[0003]
However, this diaphragm has a problem that rigidity is low because both ends in the longitudinal
direction are not bent only by bending both ends in the longitudinal direction, and noise is likely
to be generated due to unnecessary resonance accompanying vibration. The Furthermore, since a
support system such as an edge for fixing the diaphragm to the frame can be joined only to the
top surface of the diaphragm, there is also a problem that piston vibration is disturbed at large
amplitude and magnetic gap defects easily occur due to rolling.
[0004]
On the other hand, in the speaker of Patent Document 2, a voice coil pattern is formed in
advance on a thermosetting resin sheet such as a prepreg of a polyimide sheet or a laminated
sheet made of a glass resin and an epoxy resin, and heat-molded to form a cross section U It has
a letter-shaped dome shaped diaphragm. The entire periphery of the diaphragm and the frame
are joined by edges, and a support plate is fixed to the inside of the diaphragm, and the support
plate is joined to the damper on the frame side. Therefore, by making the diaphragm into a dome
shape, the rigidity can be improved, and the support structure of the diaphragm can be partially
but doubled.
[0005]
JP, 2008-113368, A JP, 2000-02094, A
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[0006]
Since the conventional electromagnetic converter is configured as described above, in the case of
the configuration of Patent Document 1, as described above, the generation of abnormal noise
due to low rigidity of the diaphragm and the generation of magnetic gap failure due to
disturbance of piston vibration There was a problem called.
On the other hand, in the case of the configuration of Patent Document 2, although the problem
of insufficient rigidity of the diaphragm can be solved, the problem that the vibration of the
piston is disturbed can be solved because the damper can be provided only partially. It was not.
[0007]
Furthermore, in the case of the configuration of Patent Document 2, the magnetic circuit has to
be divided in order to fix the damper to the frame, and there is a problem that the number of
parts increases. Further, when the magnetic circuit is divided and disposed, it causes unevenness
in the magnetic flux density and causes the magnetic flux density to decrease.
[0008]
Moreover, in order to obtain the diaphragm of the three-dimensional structure of the shape of
patent document 2 using a thermosetting resin sheet, after hardening the thermosetting resin
sheet in which the voice coil pattern was formed in three-dimensional structure, it hardens by
heat processing. In order to obtain a diaphragm having a three-dimensional structure using a
thermoplastic resin sheet, it is necessary to stretch a thermoplastic resin sheet on which a voice
coil pattern is formed by drawing using a heat press to obtain a three-dimensional shape. At this
time, since the elongation of the thermoplastic resin sheet and the elongation of the voice coil
pattern formed on the sheet are different, there is a problem that the coil and the sheet are
broken when drawn and formed. Furthermore, the thermosetting resin has a problem that the
cost is higher than that of the thermoplastic resin.
[0009]
The present invention has been made to solve the problems as described above, and it is an
object of the present invention to obtain an electromagnetic transducer with excellent
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performance by causing a diaphragm to vibrate in a piston with a dual support structure with a
small number of parts. I assume.
[0010]
An electromagnetic converter according to the present invention comprises a permanent magnet,
a magnetic circuit comprising a frame in which one magnetic pole surface of the permanent
magnet is fixed and the other magnetic pole side is open, and a plate fixed to the other magnetic
pole surface; It has a top surface in the covering position, four side surfaces formed from the top
surface toward the permanent magnet and located between the plate and the frame opening, and
a reinforcement that connects between the two opposite side surfaces, A diaphragm on which a
voice coil pattern is formed, a first support portion joined to a top surface peripheral edge of the
diaphragm and a frame opening peripheral edge and displacably holding the diaphragm, and a
side edge side peripheral edge of the diaphragm And a second support portion which is joined to
the inner peripheral surface of the frame and holds the diaphragm displaceably.
[0011]
According to the present invention, since the top surface peripheral edge of the diaphragm is
joined to the frame opening peripheral edge and the side end side peripheral edge is joined to the
inner peripheral surface of the frame, the diaphragm is constructed with a dual support structure
with a small component configuration. The piston can be oscillated, and an electromagnetic
transducer with excellent performance can be obtained.
[0012]
It is a disassembled perspective view which shows the structure of the electromagnetic converter
which concerns on Embodiment 1 of this invention.
FIG. 2 is a cross-sectional view of the electromagnetic converter according to Embodiment 1,
taken along line AA of FIG. 1;
It is sectional drawing which cut ¦ disconnected the electromagnetic converter which concerns on
Embodiment 1 along the BB line of FIG.
FIG. 4A shows a cross-sectional view of the diaphragm of the electromagnetic converter
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according to Embodiment 1 cut along the line CC in FIG. 1, and FIG. 4B shows the configuration
of the back surface. 5 is a graph of output characteristics of the electromagnetic converter
according to Embodiment 1. FIG. FIG. 13 is an external perspective view showing a modification
of the diaphragm in the electromagnetic converter according to the first embodiment. FIG. 13 is
an external perspective view showing a modification of the diaphragm in the electromagnetic
converter according to the first embodiment.
[0013]
Embodiment 1 FIG. 1 is an exploded perspective view showing a configuration of an
electromagnetic converter 10 according to Embodiment 1 of the present invention, and FIG. 2
shows a cross sectional view cut along a line AA and a cross section cut along a line BB. The
figure is shown in FIG. Moreover, sectional drawing of the diaphragm 15 cut ¦ disconnected
along CC line is shown to Fig.4 (a), and the structure of a back side is shown in FIG.4 (b). The
electromagnetic converter 10 shown in the figure includes a magnetic circuit including an upper
frame 11, a lower frame 12, two permanent magnets 13a and 13b, and two plates 14a and 14b,
a diaphragm 15, and the diaphragm 15. A first support consisting of an upper gasket 16 and an
edge 17 for holding the magnetic circuit on the upper side, and a second support consisting of a
lower gasket 18 and a damper 19 for holding the diaphragm 15 inside the magnetic circuit It
consists of In the first embodiment, the upper and lower portions are distinguished for the
purpose of explanation, but in actuality, any surface may be upper.
[0014]
The lower frame 12 fixes one magnetic pole surface of each of the permanent magnets 13a and
13b, and the upper frame 11 covers the lower frame 12 together with the permanent magnets
13a and 13b, and the other magnetic pole surface of each of the permanent magnets 13a and
13b. And an opening 11a at substantially the same height position. Plates 14a and 14b are
adhered to the other magnetic pole surfaces of the permanent magnets 13a and 13b,
respectively. Thus, the plates 14a and 14b and the opening 11a are at substantially the same
height, and the magnetic flux density between the plates 14a and 14b and the opening 11a is
high. The permanent magnets 13a and 13b and the plates 14a and 14b are separately disposed
so as not to contact the protruding portions 15i and 15j formed in the lower part of the side
surfaces 15b and 15c in the longitudinal direction of the diaphragm 15.
[0015]
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For the diaphragm 15, a thermoplastic resin sheet such as PEI (polyether imide), PEN
(polyethylene naphthalate), PET, PEEK (polyether ether ketone) is used. A conductor coil (copper,
aluminum, etc.) is edged on one side or both sides of the thermoplastic resin sheet prior to threedimensional molding at positions corresponding to the top surface 15a and the side surfaces 15b
and 15c in the longitudinal direction to form a voice coil pattern 15g And three-dimensional
structure by heat press molding. The rigidity of the diaphragm 15 can be improved by forming
the four sides of the diaphragm 15 into four side surfaces 15b to 15e depending from the top
surface 15a by heat press molding. In the illustrated example, the side surfaces 15b and 15c in
the longitudinal direction are formed to hang vertically from the top surface 15a, and the side
surfaces 15d and 15e in the short direction are formed to hang obliquely from the top surface
15a. The side surfaces 15b and 15c in the longitudinal direction on which the voice coil pattern
15g is formed can be molded without stretching the thermoplastic resin sheet at the time of heat
press molding, so there is no fear of breakage due to the difference in elongation rate.
[0016]
Moreover, the flange part 15f is shape ¦ molded on the front end side of side 15b-15e. The flange
portion 15 f serves as a fixing margin when the diaphragm 15 is bonded to the damper 19.
Further, tongue-like protruding portions 15i and 15j, which extend the thermoplastic resin sheet,
are formed on the side surfaces 15b and a part of the tip side of the side surface 15c. It is
generated at the time of driving by forming fitting convex part 15k in one of these projecting
parts 15i and 15j, forming a hole in the other, fitting and adhering fitting convex part 15k to the
hole and making it into a band shape. It becomes a reinforcement for vibration.
[0017]
Further, in the illustrated example, the voice coil patterns 15 g are formed on both the front and
back sides of the diaphragm 15. Here, the voice coil patterns 15g formed on the front and back
surfaces of each of the side surfaces 15b and 15c in the longitudinal direction of the diaphragm
15 are arranged such that the pattern on the front surface and the pattern on the back surface
overlap each other. Increase the rigidity of
[0018]
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The peripheral edge of the opening 17 a of the edge 17 is joined to the peripheral edge of the
top surface 15 a of the diaphragm 15, and the outer peripheral edge of the edge 17 is joined to
the peripheral edge of the opening 16 a of the upper gasket 16. Upper gasket 16 is secured to
the upper surface of upper frame 11. The upper gasket 16 and the edge 17 serve as a first
support portion to support the diaphragm 15 so as to be vertically displaceable. The outer
peripheral edge of the edge 17 may be directly joined to the upper frame 11 without using the
upper gasket 16. In that case, it is necessary to secure a predetermined distance between the top
surface 15a and the plates 14a and 14b so as not to collide with the plates 14a and 14b when
the diaphragm 15 is displaced up and down. A portion of the upper surface may be protruded
upward for height alignment, or the outer peripheral edge of the edge 17 may be extended to the
upper surface of the upper frame 11.
[0019]
The periphery of the opening 19 a of the damper 19 is joined to the flange portion 15 f of the
peripheral edge of the side surface of the diaphragm 15, and the outer periphery of the damper
19 is joined to the periphery of the opening 18 a of the lower gasket 18. The lower gasket 18 is
fixed to the upper back surface of the upper frame 11, that is, the inside of the magnetic circuit.
The lower gasket 18 and the damper 19 serve as a second support portion to support the
diaphragm 15 so as to be vertically displaceable. The outer peripheral edge of the damper 19
may be directly joined to the inside of the upper frame 11 without using the lower gasket 18.
[0020]
In a general electromagnetic converter having a conical diaphragm, a material having no air
permeability at the edge is used. However, in the electromagnetic converter 10 according to the
first embodiment, the edge 17 is permeable to air. A good material or a structure that allows air
to permeate may be used. Thereby, the sound generated from the side surfaces 15 b and 15 c of
the diaphragm 15 can be used. That is, the sound generated from the side surfaces 15b and 15c
of the diaphragm 15 passes through the edge 17 and is synthesized with the sound generated
from the top surface 15a, thereby improving the high-pitched sound reproduction performance
of the electromagnetic converter 10.
[0021]
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FIG. 4 is a graph comparing the reproduction performance of the electromagnetic converter 10
according to the difference in the material of the edge 17. The vertical axis represents the sound
pressure level, and the horizontal axis represents the frequency. In this example, the frequency of
the electromagnetic converter 10 in the case where the edge 17 is made of an elastomer which
does not transmit air (shown by a solid line) and in the case where the edge is made of a
polyester woven weakly woven (shown by a dotted line). The characteristics are illustrated. From
this graph, it can be seen that the use of the air-permeable edge 17 provides a better high-range
characteristic. At this time, the damper 19 is made of a material that does not transmit air or a
structure that does not transmit air in order to prevent the sound of the opposite phase emitted
from the rear surface of the diaphragm 15 from being emitted to the front surface of the
electromagnetic converter 10.
[0022]
Next, the operation principle of the electromagnetic converter 10 will be described. When
current (audio signal) is supplied from the outside to the voice coil pattern 15g, the current
flowing through the voice coil pattern 15g and the magnetic flux generated between the opening
11a of the upper frame 11 and the plates 14a and 14b are electromagnetically The driving force
is generated according to Fleming's law. The vibrating plate 15 vibrates in the vertical direction
by the generated driving force, and a sound wave is generated. The whole circumference of the
top surface 15a of the diaphragm 15 and the whole circumference of the flange portion 15f are
supported so as to be vertically displaced by the first and second support portions, respectively.
Absent. Therefore, no magnetic gap failure occurs due to rolling.
[0023]
Further, since the reinforcing portion formed by fitting and bonding the protruding portions 15i
and 15j suppresses unnecessary resonance of the side surfaces 15b and 15c, the diaphragm 15
does not collide with the permanent magnets 13a and 13b and the plates 14a and 14b, and no
hitting noise occurs. . Furthermore, since the voice coil patterns 15g on the side surfaces 15b and
15c in the longitudinal direction of the diaphragm 15 partially overlap on the front and back
surfaces, the rigidity of the side surfaces 15b and 15c is increased, and unnecessary resonance is
reduced. Therefore, generation of abnormal noise can be suppressed.
[0024]
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As described above, according to the first embodiment, the electromagnetic converter 10
includes the permanent magnets 13a and 13b, the lower frame 12 for fixing one of the magnetic
pole faces of the permanent magnets 13a and 13b, and the opening 11a on the other magnetic
pole side. Magnetic circuit comprising the upper frame 11 formed and the plates 14a and 14b
fixed to the other magnetic pole surface, the top surface 15a at a position covering the plates 14a
and 14b, and the direction from the top surface 15a to the permanent magnets 13a and 13b The
diaphragm 15 having four side surfaces 15b to 15e formed between the plates 14a and 14b and
the opening 11a of the upper frame 11 and having the voice coil pattern 15g formed on one side
or both sides and the opening of the upper frame 11 11a, the upper gasket 16 bonded to the
periphery, the top surface 15a of the diaphragm 15 and the periphery of the opening 16a of the
upper gasket 16 The edge 17 which holds the diaphragm 15 displaceably by bonding, the lower
gasket 18 adhered to the inner peripheral surface of the upper frame 11, the flange 15f of the
diaphragm 15 and the periphery of the opening 18a of the lower gasket 18 It joined and it
comprised so that the damper 19 which holds the diaphragm 15 displaceably could be provided.
For this reason, the diaphragm 15 can be supported by the dual support structure with a small
number of parts and the piston can be vibrated, and generation of abnormal noise can be
prevented. Further, it is not necessary to divide the magnetic circuit as in the prior art, and the
number of parts is not increased and the cost is not increased. Furthermore, since it is not
necessary to divide and arrange the magnetic circuit, neither unevenness in magnetic flux density
nor magnetic flux density is reduced.
[0025]
Further, according to the first embodiment, the diaphragm 15 has the four side surfaces 15b to
15e formed by heat-press forming both ends in the longitudinal direction and both ends in the
width direction of the thermoplastic resin sheet. The coil pattern 15g is disposed on the side
surfaces 15b and 15c and the top surface 15a in the longitudinal direction. Therefore, it is
possible to use a low cost thermoplastic resin instead of a high cost thermosetting resin, and as a
result, an inexpensive electromagnetic converter 10 can be obtained.
[0026]
Further, according to the first embodiment, the two opposing side surfaces 15b and 15c of the
diaphragm 15 are extended to form the tongue-like protruding portions 15i and 15j and to bond
them, thereby forming the space between the side surfaces 15b and 15c. The reinforcement part
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to connect was comprised. For this reason, the diaphragm 15 can be reinforced with a small
number of parts without newly providing a structure for reinforcing the diaphragm 15.
[0027]
Further, although not shown in the drawing, a rib structure or a concavo-convex structure for
enhancing the rigidity of the diaphragm 15 may be formed on the tongue-like protruding
portions 15i, 15j of the diaphragm 15. By providing a reinforcing structure in the strip-like
protruding portions 15i and 15j transferred to the side surfaces 15b and 15c, the rigidity of the
diaphragm 15 can be further improved, and the performance of the electromagnetic converter
10 can be enhanced. Furthermore, the connection between the side surfaces 15b and 15c is not
limited to only one place by adhesion of the protruding parts 15i and 15j, and even if the
protruding parts are formed in a plurality of places to increase the number of connections. Good.
[0028]
Further, according to the first embodiment, the voice coil patterns 15g are formed on both the
front and back sides of the side surfaces 15b and 15c of the diaphragm 15, and the front surface
pattern and the rear surface pattern partially overlap each other. Therefore, the rigidity of the
diaphragm 15 can be further improved by eliminating the portion of only the thermoplastic resin
sheet whose strength is inferior to the conductor pattern made of copper, aluminum or alloy
having high rigidity, and the electromagnetic converter 10 can be further improved. Performance
can be enhanced.
[0029]
Further, according to the first embodiment, since the edge 17 is made of a material or a structure
through which air passes, the sound generated from the top surface 15 a and the side surfaces
15 b to 15 e of the diaphragm 15 is output from the front surface of the electromagnetic
converter 10 Thus, it is possible to improve the high-range reproduction performance. At this
time, if the damper 19 is made of a material or a structure which does not transmit air, it is
possible to prevent the sound of the opposite phase coming out of the back surface of the
diaphragm 15 from coming out of the front surface of the electromagnetic converter 10. It can
be enhanced.
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[0030]
A reinforcing structure 15 h may be formed on the top surface 15 a of the diaphragm 15 to
increase the rigidity of the diaphragm 15. 6 and 7 are perspective views showing the structure of
a reinforcing structure 15h provided on the diaphragm 15 according to the first embodiment.
The reinforcing structure 15h may be realized by a rib structure or a concavo-convex structure,
and the formation direction of the rib or the concavo-convex may be the longitudinal direction or
the transverse direction of the diaphragm 15 as shown in FIGS. By providing the reinforcing
structure 15h on the top surface 15a, the rigidity of the diaphragm 15 can be further improved,
and the performance of the electromagnetic converter 10 can be improved.
[0031]
In the first embodiment, the method of forming the voice coil pattern 15g by edging before hotpressing the diaphragm 15 has been described, but the present invention is not limited to this.
The voice coil pattern 15g may be printed and formed, or a voice coil pattern 15g may be formed
by attaching a coil to the diaphragm 15 after three-dimensional formation.
[0032]
DESCRIPTION OF SYMBOLS 10 electromagnetic converter, 11 upper frame (frame), 11a, 16a,
17a, 18a, 19a opening, 12 lower frame (frame), 13a, 13b permanent magnet, 14a, 14b plate, 15
diaphragm, 15a top surface, 15b, 15c, 15d, 15e side surface, 15f flange portion, 15g voice coil
pattern, 15h reinforcing structure, 15i, 15j projecting portion, 15k fitting convex portion, 16
upper gasket (first support portion), 17 edge (first) 18) lower gasket (second support), 19
damper (second support).
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