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JP2010252028

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DESCRIPTION JP2010252028
An object of the present invention is to provide an electromagnetic converter in which a driving
force can be obtained efficiently by applying a magnetic field of high magnetic flux density to a
coil of a vibrating film. A spacer (33) is provided between a pair of frames (31, 32), permanent
magnets (11, 13) are arranged in a zigzag on inner wall surfaces of the pair of frames (31, 32),
and plates (12, 14) are arranged on permanent magnets (11, 13). The vibrating membrane 15 is
disposed on a straight line in the horizontal direction, at an interval between the plates 12 and
14 and the pair of frames 31 and 32 and the spacer 33 and at an interval between the plates 12
and 14, and an interval between the plates 12 and 14 The coil pattern 15 b of the vibrating
membrane 15 was disposed at an interval between the plate 14 and the frame 32 or the spacer
33. [Selected figure] Figure 2
Electromagnetic converter
[0001]
The present invention relates to, for example, an electromagnetic transducer that combines a
permanent magnet and a vibrating membrane and reproduces sound from an audio signal.
[0002]
Various techniques have been proposed for an electromagnetic transducer combining a
permanent magnet and a vibrating membrane.
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According to Patent Document 1, for example, such an electromagnetic converter includes a
permanent magnet plate, a vibrating membrane disposed to face the permanent magnet plate,
and a buffer disposed between the permanent magnet plate and the vibrating membrane. And a
member.
[0003]
The permanent magnet is one in which strip-like different magnetic poles are alternately formed
with a constant interval (also referred to as a gap) (also referred to as a multi-pole magnetization
pattern). In addition, in the vibrating film, a coil (also referred to as a coil pattern) formed of a
meander-shaped conductor pattern is formed at a position opposite to a portion called a neutral
zone of so-called magnetization of the gap between different magnetic poles of permanent
magnet plates. It is done. In a general electromagnetic transducer, each of these members is
covered by a frame, and the frame is configured to be attached to the speaker housing.
[0004]
In the electromagnetic converter having such a configuration, the magnetic poles of the
permanent magnet plate are arranged to face up and down on the inner surface of the frame, and
a magnetic field is generated in the gap between the magnetic poles. The coil pattern of the
vibrating film is provided at a position facing the gap between the magnetic poles, and when
current (audio signal) flows through the coil pattern of the vibrating film, the coil pattern and the
multipolar magnetization pattern of the permanent magnet plate By electromagnetically
coupling, audio vibration occurs in the vibrating film according to Fleming's law. Audio vibration
is emitted to the outside by sound emission holes and the like formed in the frame to perform
sound reproduction.
[0005]
JP-A-9-331596
[0006]
However, in the conventional electromagnetic converter, since the coil pattern is formed at a
position facing the gap between the magnetic poles, the coil pattern formed on the vibrating film
is driven by the leakage flux of the magnetic field generated in the gap. , Was inefficient.
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[0007]
The present invention has been made to solve the above-mentioned problems, and to provide an
efficient electromagnetic transducer for driving a coil pattern formed on a vibrating film with a
magnetic field of high magnetic flux density between permanent magnets. To aim.
[0008]
The electromagnetic transducers according to the present invention are arranged such that a
hollow is formed when they are combined, and at the same time, the pair of frames in which at
least one end is bent and the opposing inner wall surfaces of the pair of frames. Rod-like
permanent magnets fixed so as to be arranged in a staggered arrangement in the direction of the
magnetic poles and a plate fixed so as to be aligned in a horizontal direction on the surface
opposite to the fixed surface of the permanent magnet frame; A spacer disposed in the vicinity of
the plates fixed to the staggered outer permanent magnets between the ends of the pair of
frames, and the cross section being uneven so as to be disposed between each plate and between
the plate and the frame or spacers And a coil pattern is formed in the vicinity between each plate
and in the vicinity between the plate fixed to the staggered outer permanent magnets and the
spacer Is that a Domaku.
[0009]
According to the electromagnetic converter of the present invention, the coil pattern on the
vibrating film can be driven by the magnetic field of high magnetic flux density between the
permanent magnets by the permanent magnet, the plate and the vibrating film configured as
described above, The driving force can be efficiently obtained, and the coil pattern of the outer
end on the vibrating membrane is driven by the magnetic field having the same high magnetic
flux density as the magnetic flux density between the permanent magnets by the spacer and the
vibrating membrane configured as described above The uniform driving force can be obtained on
the vibrating membrane.
As a result, an electromagnetic transducer with good acoustic characteristics can be obtained.
[0010]
It is an (a) external appearance perspective view which shows the structure of the
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electromagnetic converter of Embodiment 1, and (b) is a disassembled perspective view.
It is the sectional view on the AA line of FIG.
FIG. 5 is a cross-sectional view showing a length a of a folded back portion of a frame, a magnetic
field generation position # 1 between plates, and a magnetic field generation position # 2
between the frame and the plate in the electromagnetic converter of the first embodiment.
FIG. 6 is a graph showing a change in magnetic flux density at positions # 1 and # 2 when the
length a of the folded back portion of the frame shown in FIG. 3 is changed. FIG. 13 is a crosssectional view showing a structure in which one frame is not provided with a folded portion in
the electromagnetic converter of the first embodiment, and is a cross-sectional view showing the
configuration of the electromagnetic converter of the second embodiment.
[0011]
Hereinafter, embodiments of the present invention will be described in detail with reference to
the drawings. Embodiment 1 FIG. 1 is a perspective view for explaining the configuration of the
electromagnetic converter according to the first embodiment, FIG. 1 (a) is an external perspective
view, and FIG. 1 (b) is an exploded perspective view. As shown in FIGS. 1 (a) and 1 (b), the
electromagnetic converter 1 is composed of permanent magnets 11 and 13, plates 12 and 14, a
diaphragm 15, and a frame 30. The frame 30 is a box structure arranged to form a hollow when
the upper frame 31, the lower frame 32 (a pair of frames) and the spacer 33 are combined, and
on the surface of the upper frame 31 and the lower frame 32 The sound emission holes 31a and
32a which connect the inside and the outside of the flame | frame 30 are formed.
[0012]
The permanent magnets 11 and 13 have a rod-like shape, and plates 12 and 14 made of a
magnetic material are adhered to one surface of the permanent magnets 11 and 13.
[0013]
The vibrating membrane 15 is formed by forming a coil (hereinafter referred to as a coil pattern)
15b composed of a meander-shaped conductor pattern on the front and back surfaces of a
vibrating membrane base 15a composed of a thin and flexible resin film.
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[0014]
FIG. 2 is a cross-sectional view of the electromagnetic converter 1 cut along the line A-A shown in
FIG. 1, and the permanent magnets 11 and 13, the plates 12 and 14, the diaphragm 15, and the
upper frame 31 in the electromagnetic converter 1. , The lower frame 32 and the spacer 33 are
shown.
[0015]
As shown in FIG. 2, the permanent magnets 11 and 13 have the same direction of the magnetized
poles, and are fixed in a staggered arrangement on the opposing inner wall surfaces of the upper
frame 31 and the lower frame 32 with a predetermined interval. ing.
[0016]
The plate 12 is bonded and fixed to the surface facing the fixing surface of the permanent
magnet 11 and the upper frame 31, and the plate 14 is bonded to the surface facing the fixing
surface of the permanent magnet 13 and the lower frame 32. It is fixed.
Further, the plates 12 and 14 are arranged in line in the horizontal direction.
[0017]
The plates 12 and 14 are made of a magnetic substance such as iron and placed on the
magnetized permanent magnets 11 and 13, for example, as shown by arrows in FIG. 2, the
magnetic flux density with different nearby magnetic poles is concentrated It is acting like.
[0018]
The upper frame 31 and the lower frame 32 are formed with folded portions 31 b and 32 b in
which both ends are bent, and a spacer 33 is disposed between the outer ends of the folded
portions 31 b and 32 b.
The spacer 33 is made of, for example, a nonmagnetic material, and forms a gap portion having a
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predetermined height so that the outer ends of the bent portions 31b and 32b of the upper and
lower frames 31 and 32 do not contact each other.
As shown in FIG. 2, the spacers 33 are provided on the upper frame 31 to which the staggered
outer permanent magnets 13 are not fixed, and are arranged in the vicinity of the plate 14 fixed
to the permanent magnets 13.
[0019]
The vibrating membrane base 15a of the vibrating membrane 15 is formed to have an uneven
cross section, and has a vibrating membrane convex portion 15c, a vibrating membrane concave
portion 15d, and a vibrating membrane acting portion 15e.
The vibrating membrane convex portion 15c is disposed between the plate 14 and the upper
frame 31, the vibrating membrane concave portion 15d is disposed between the plate 12 and the
lower frame 32, and the vibrating membrane acting portion 15e is the plate 14 and the plate 12
Between the plate 14 and the lower frame 32 and between the plate 14 and the spacer 33.
The vibrating membrane acting portion 15e is a connection portion between the vibrating
membrane convex portion 15c and the vibrating membrane concave portion 15d, and the center
of the vibrating membrane acting portion 15e is disposed substantially in the middle between the
plates 12 and 14.
[0020]
Next, the operation principle of the electromagnetic converter 1 will be described. Between the
plates 12 and 14 mounted on the permanent magnets 11 and 13, a magnetic field is generated
so as to cross the vibrating film acting portion 15e of the vibrating film 15. When a current
(audio signal) is supplied to the coil pattern 15b from the outside, the coil pattern 15b and the
permanent magnets 11 and 13 are electromagnetically coupled, and a driving force is generated
in accordance with Fleming's law. The vibrating film 15 vibrates by the driving force of the
generated coil pattern 15b, and this vibration is radiated from the sound emission holes 31a and
32a to the outside, and is reproduced as sound.
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[0021]
Next, the magnetic flux density acting on the coil pattern 15b of the vibrating membrane acting
portion 15e will be described. FIG. 3 is a cross-sectional view in which a part of the
electromagnetic converter 1 cut along the line AA shown in FIG. 1 is omitted, and the length a of
the folded portion 31 b of the upper frame 31 and the generation position of the magnetic flux
density Shows an interval # 1 and an interval # 2. An interval # 1 is an interval between the plate
14 and the plate 12, and an interval # 2 is an interval between the plate 14 and the frame 32,
and an interval between the plate 14 and the spacer 33. In FIG. 4, the dimensions # 1 of the
permanent magnets 11 and 13 when the width W = 6.5 mm and the depth D = 5.5 mm, and the
length a (mm) of the folded portion 31b of the upper frame 31 is changed , # 2 show changes in
magnetic flux density.
[0022]
When the upper and lower frames 31 and 32 are brought into contact with each other in the
electromagnetic converter 1 as described above, the magnetic flux density at the interval # 2
decreases as shown in FIG. Since the magnitude of the magnetic flux density at the interval # 1 is
different and the generated driving force is different, there is a problem that the driving force is
unbalanced on the vibrating film 15.
[0023]
To address this problem, in the first embodiment, as described above, the spacer 33 made of a
nonmagnetic material or the like is provided as a gap between the upper frame 31 and the lower
frame 32 to configure the frame 30, The magnetic flux density in the space # 2 between the plate
14 and the frame 30 is prevented from being extremely reduced, but the length a (mm) of the
folded portion 31b of the frame 31 shown in FIG. An electromagnetic transducer having good
acoustic characteristics can be obtained.
[0024]
As shown in FIG. 4, when the dimensions of the permanent magnets 11 and 13 are set to a width
W = 6.5 mm and a depth D = 5.5 mm, the length a (mm) of the folded portion 31b is
approximately 3 mm. The magnetic flux density in the space # 1 between the plates 12 and 14
and the magnetic flux density in the space # 2 between the plate 14 and the frame 30 can be
made equal.
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[0025]
The magnetic flux density in the space # 1 between the plates 12 and 14 and the magnetic flux
density in the space # 2 between the plate 14 and the frame 30 are made equal by the change in
the dimension of the permanent magnets 11 and 13 or the difference in capacity. The length a of
the folded back portion 31b of the upper frame 31 is different.
[0026]
Further, depending on the size or ability of the permanent magnets 11 and 13, both ends of the
frame 31 may not be folded back.
For example, FIG. 5 is a cross-sectional view showing a structure in which both ends of the upper
frame 31 are not folded back. As shown in FIG. 5, instead of the folded part 31 b of the upper
frame 31 in FIG. It may be provided.
[0027]
As described above, in the electromagnetic converter 1 according to the first embodiment, the
permanent magnets 11 and 13 are staggered on the opposing inner wall surfaces of the upper
and lower frames 31 and 32, and the plate 12 is fixed to the permanent magnets 11 and 13. , 14
are arranged in a straight line in the horizontal direction, and the coil pattern 15b of the
vibrating film 15 is arranged between the plates 12, 14 to give the coil pattern 15b a strong
magnetic flux density of the permanent magnets 11, 13. it can.
[0028]
Further, by arranging the spacer 33 so as to provide a gap between the upper frame 31 and the
lower frame 32, the coil pattern 15b at the outer end of the vibrating membrane 15 is also
subjected to the magnetic field of strong magnetic flux density and driven. You can get it.
[0029]
Furthermore, by adjusting the length a of the folded portion 31 b of the upper frame 31, that is,
by setting the height of the spacer 33 to a predetermined height and providing a predetermined
gap portion between the upper frame 31 and the lower frame 32. The magnetic flux density in
the space # 2 between the plate 14 and the upper and lower frames 31 and 32 and the magnetic
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flux density in the space # 1 between the plates 12 and 14 can be made equal, and uniform
driving on the vibrating film 15 is possible. Power is obtained.
As a result, it is possible to obtain an electromagnetic transducer 1 having good acoustic
characteristics.
[0030]
Second Embodiment
In the first embodiment, the end portions of the folded portions 31 b and 32 b of the upper and
lower frames 31 and 32 are connected via the spacer 33, but in the second embodiment, the
plate 14 and the lower frame 32 are connected. The configuration for further increasing the
magnetic flux density at the interval # 2 will be described.
[0031]
FIG. 6 is a cross-sectional view of the electromagnetic converter 1 cut along the line A-A of FIG.
The configuration in FIG. 6 is the same as that in FIG. 1 or the like except that the protrusion 32 c
is provided, and therefore the same configuration is denoted by the same reference numeral and
the description thereof is omitted.
[0032]
As shown in FIG. 6, the lower frame 32 forms a projection 32 c formed by bending the folded
portion 32 b in the inward direction of the lower frame 32.
The projections 32 c act to concentrate the magnetic flux density on the plates 14 fixed to the
staggered outer permanent magnets 13.
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[0033]
With the electromagnetic converter 1 of the second embodiment configured as described above,
the magnetic flux density is concentrated between the protrusion 32 c and the plate 14 mounted
on the permanent magnet 13, so that the same configuration as that of the first embodiment can
be obtained. The effect can be obtained, and the magnetic flux density can be concentrated on
the coil pattern 15b of the vibrating membrane 15 more effectively.
[0034]
Note that FIGS. 1 to 6 are exaggeratingly enlarged for simplifying the explanation, and are
different from the actual scale, and some are omitted to facilitate the explanation. ing.
[0035]
Further, although the upper and lower sides of the frame are distinguished for ease of
explanation here, the upper and lower sides may be reversed.
[0036]
As described above, in the electromagnetic converter according to the present invention, the
permanent magnets 11 and 13 are staggered on the opposing inner wall surfaces of the upper
and lower frames 31 and 32, and the plates 12 and 14 are fixed to the permanent magnets 11
and 13. Are arranged in a straight line in the horizontal direction, and the coil pattern 15b of the
vibrating film 15 is arranged between the plates 12 and 14 and between the plate 14 and the
frame 30. The upper frame 31 and the lower frame 32 The spacer 33 is provided at the outer
end of the upper frame 31 as a gap portion of the upper frame 31 so that the coil pattern 15b is
driven by the magnetic field having a strong magnetic flux density equivalent to the magnetic
flux density between the permanent magnets 11 and 13 Since they can be driven uniformly and
efficiently, an electromagnetic converter having good acoustic characteristics can be obtained,
and therefore, they are suitable for use in acoustic devices and the like.
[0037]
Reference Signs List 1 electromagnetic transducer 11, 13 permanent magnet 12, 14 plate 15
vibrating membrane 15a vibrating membrane base 15b coil pattern 15c vibrating membrane
convex portion 15d vibrating membrane concave 15e vibrating membrane acting portion 30
frame 31 upper frame, 31a, 32a sound output hole, 31b, 32b folded portion, 32 lower frame,
32c protrusion, 33 spacer.
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