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DESCRIPTION JP2010278591

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DESCRIPTION JP2010278591
The present invention provides a speaker unit capable of creating a large sound field space even
in a high frequency range with high sound quality with little noise. A speaker unit is configured
to drive a diaphragm (5) through a voice coil (3) by a magnetic circuit (2) including a pole piece
(24), and the diaphragm (5) faces an upper end face of the pole piece (24). A center cap 8 is
provided at the center of the diaphragm 5 opposite to the upper end face of the pole piece 24.
On the upper end face of the pole piece 24, there is fixed a sheet member 6 having a cutout 63
which has an internal loss larger than that of the pole piece 24 and which radially extends from
the inner peripheral portion to the outer peripheral portion of the upper end face of the pole
piece 24 Ru. [Selected figure] Figure 1
スピーカユニット
[0001]
The present invention relates to a dynamic type speaker unit provided with a magnetic circuit
including a magnetic circuit including a pole piece that generates a direct current magnetic field
acting on a voice coil, and can reproduce high quality sound with particularly low noise and
create a large sound field space even in a high sound range. The present invention relates to a
speaker unit that can be
[0002]
The speaker unit is roughly classified into a dynamic type (electrokinetic type) and a capacitor
type (electrostatic type) according to a method of converting an alternating current electrical
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signal into mechanical vibration, but the mainstream is a dynamic type.
A dynamic speaker unit has a voice coil placed in a direct current magnetic field formed by a
magnetic circuit including a pole piece, and is configured to drive a diaphragm by Lorentz force
generated there (for example, Patent Document 1).
[0003]
The magnetic circuit includes an internal magnet type and an external magnet type, and in each
of the voice coils, a pole piece constituting a magnetic circuit is inserted. In addition, the
diaphragms joined to the voice coil include a dome type, a flat type, a cone type, etc., and the
whole of the dome type diaphragm is bonded to the voice coil facing the upper end face of the
pole piece and the flat type diaphragm Is partially joined to the voice coil so as to face the upper
end face of the pole piece, and in the case of a cone type diaphragm, a center cap opposite to the
upper end face of the pole piece is mounted at the center thereof. The upper end surface of the
pole piece refers to the surface on the diaphragm side in a state in which the speaker unit is
placed with the diaphragm on the upper side.
[0004]
JP 2003-333688 A
[0005]
In the speaker unit as described above, when the center cap or diaphragm opposed to the upper
end face of the pole piece vibrates, the sound radiated to the back side of them vibrates on the
pole piece to generate echo sound, or the pole piece It resonates to generate resonance sound.
The echo sound and resonance sound are mixed with the sound directly radiated forward from
the diaphragm and are heard as offensive noise.
[0006]
Therefore, it is also practiced to fill a sound absorbing material such as glass wool between the
pole cap and the center cap or the back side of the diaphragm, but according to this, it is
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necessary to suppress the generation of echo and resonance noise due to the pole piece. Even if it
is possible, the reproduced sound is aurally turbid and the high-range sound does not spread, so
the directivity in the high range is sharp and a large sound field space can not be created.
[0007]
The present invention has been made in view of the above-described circumstances, and an
object thereof is to provide a speaker unit capable of creating a large sound field space with high
sound quality with little noise and high pitch.
[0008]
In order to achieve the above object, a speaker unit according to the present invention comprises:
a voice coil 3 formed by winding a conductive wire around a coil bobbin 31; a magnetic circuit 2
including a pole piece 24 inserted inside the voice coil 3; From the inner peripheral portion to
the outer peripheral portion of the diaphragm 5 joined to the tip of the voice coil 3 and the inner
surface of the opposing surface of the pole piece 24 opposite to the diaphragm 5 with an internal
loss larger than that of the pole piece 24 And a sheet member 6 having a radially extending
cutout 63 attached to the opposing surface.
[0009]
The diaphragm 5 is characterized by being a dome-shaped diaphragm.
The diaphragm 5 is a cone-shaped diaphragm having a central hole 5a communicating with the
voice coil 3, and further includes a center cap 8 covering the central hole 5a.
[0010]
The sheet member 6 is made of a plastic film, a rubber sheet, paper, non-woven fabric, or woven
fabric.
[0011]
According to the speaker unit according to the present invention, the sheet member has a cutout
portion which has an internal loss larger than that of the pole piece and which radially extends
from the inner peripheral portion to the outer peripheral portion of the opposing surface facing
the diaphragm of the pole piece. Since it is stuck on the opposite surface of the pole piece, the
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sound radiated to the back side from the diaphragm or center cap opposite to the opposite
surface of the pole piece is attenuated to suppress the generation of resonance sound or echo
due to the pole piece Meanwhile, the sound can be spread radially and the sound field can be
expanded by the function of the cutout part that exposes the opposite surface of the pole piece.
[0012]
In particular, in the case of a sheet member made of plastic film, rubber sheet, paper, non-woven
fabric, or woven fabric, the material itself is not so expensive, so the product cost can be
suppressed, and moreover, it has a moderate internal loss larger than the pole piece. The
suppression effect of resonance noise and echo due to
[0013]
Sectional drawing which shows the speaker unit which concerns on one embodiment of this
invention Schematic which shows the front end surface of the pole piece which fixed the sheet
member Explanatory drawing which shows the modification of a sheet member which concerns
on one embodiment of this invention Cross section showing a modification
[0014]
Hereinafter, an embodiment of the present invention will be described in detail based on the
drawings.
First, referring to FIG. 1, an embodiment of a speaker unit according to the present invention will
be described. The speaker unit is an electrodynamic (dynamic) tweeter (for high sound).
Reference numeral 1 denotes a frame of the speaker unit, and a magnetic circuit 2 (external
magnet type in the illustrated example) is attached to the frame 1.
[0015]
The magnetic circuit 2 is mounted on a ring-shaped magnet 21 magnetized in the thickness
direction, a ring-shaped top plate 22 mounted on one of the magnetic poles of the magnet 21,
and the other magnetic pole of the magnet 21. And a pole piece 24 provided at the center of the
back plate 23. A magnetic gap G in which the magnetic flux of the magnet 21 acts is formed
between the pole piece 24 and the top plate 22. It is done.
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[0016]
The top plate 22, the back plate 23, and the pole piece 24 become a yoke for collecting the
magnetic flux of the magnet 21 in the magnetic gap G, and the voice coil 3 is inserted in the
magnetic gap G.
The back plate 23 and the pole piece 24 may be integrally formed.
[0017]
The voice coil 3 is formed by winding a conductive wire such as copper or aluminum coated with
an insulating film around the outer periphery of a non-conductive (a conductive nonmagnetic
material such as aluminum may be used) made of paper or the like. The upper end portion of the
pole piece 24 is inserted into the inner periphery of the wire portion 32, and the inner peripheral
surface of the top plate 22 faces the winding portion 32 of the outer periphery.
The voice coil 3 is attached to the frame 1 via the damper 4 and supported movably in the frontrear direction (the direction of the axis passing through the center of the voice coil 3 and in the
vertical direction in FIG. 1) by the damper 4 Its tip is joined to the dome-shaped diaphragm 5.
[0018]
The diaphragm 5 is a dome-shaped radiator formed of paper, wood, or a synthetic resin such as
polypropylene or polyester, aluminum or other metal, or chemical fiber, as is apparent from FIG.
Of the voice coil 3 so as to face the upper end surface of the voice coil 3.
The upper end surface of the pole piece 24 is an opposing surface opposed to the back surface of
the diaphragm 5.
[0019]
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Then, according to the speaker unit configured as described above, it is known that the voice
current flows in the voice coil 3 (precisely, the winding portion 32) orthogonal to the magnetic
lines of the direct current magnetic field generated in the magnetic gap G. Thus, the voice coil 3
vibrates by obtaining an oscillating force in the axial direction, and the vibration is converted to
air vibration through the diaphragm 5 so that sound can be reproduced.
[0020]
When the diaphragm 5 vibrates in the front-rear direction (vertical direction in FIG. 1), the sound
radiated to the back side (the rear side where the pole piece 24 is located) is reflected to the pole
piece 24 to generate echo sound. The pole piece 24 resonates to generate a resonant sound.
Therefore, according to the present embodiment, the sheet member 6 instead of the conventional
sound absorbing material is attached and fixed (fixed) to the upper end surface of the pole piece
24 with an adhesive or the like.
[0021]
The sheet member 6 is a sheet having a thickness of about 0.1 to 3 mm, particularly a nonmetallic sheet different in material from the pole piece 24 and is made of polypropylene (PP) or
the like which has an internal loss larger than the pole piece 24 exhibiting sound absorbing
performance. It is made of plastic film such as polyvinyl chloride (PVC), rubber sheet, paper, nonwoven fabric including felt and tufted cloth, or woven fabric.
Among these, for example, the internal loss of polypropylene is 0.08, and the internal loss of
paper is 0.025 to 0.055.
In addition, the pole piece 24 consists of magnetic metal with respect to the sheet | seat member
6 of that kind, Although the internal loss changes with materials, it is about 0.001 to about 0.01.
[0022]
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6
FIG. 2 shows the upper end surface of the pole piece 24 to which the sheet member 6 as
described above is fixed. As is apparent from FIG. 2, the sheet member 6 has a circular shape
identical to the upper end surface of the pole piece 24 and has a shape anisotropy that does not
entirely cover the upper end surface of the pole piece 24. Specifically, an annular portion 61
along the outer periphery of the pole piece 24 and a plurality of (four in the illustrated example)
projecting pieces 62 extending from the inner peripheral edge of the annular portion 61 toward
the center thereof are connected in a row. The cutouts 63 are cut out and opened between the
projecting pieces 62. The cutout portion 63 is located inside the annular portion 61 and formed
between the projecting piece portions 62, and radially extends from the inner peripheral portion
to the outer peripheral portion of the upper end surface of the pole piece 24. And a circular arc
portion 64 concentric with the circle.
[0023]
Then, according to the sheet member 6 as described above, the annular portion 61 and the
projecting portion 62 covering the upper end face of the pole piece 24 absorb the sound radiated
to the back side of the diaphragm 5 and resonate by the pole piece 24 The cut-out portion 63
and the arc portion 64 exposing the upper end face of the pole piece 24 do not inhibit the
propagation of the high-frequency range component by the pole piece 24 while suppressing the
sound and echo. Especially, the cut-out portion 63 It spreads radially and acts to expand the
sound field. In short, the sheet member 6 imparts acoustic anisotropy to the pole piece 24 as a
whole, and suppresses the resonance sound and echo from the pole piece 24 while the high-pitch
range is the radial direction of the upper end face of the pole piece 24 Work in the direction).
[0024]
Here, when the acoustic performance of the speaker unit of the present embodiment having the
sheet member 6 as described above and the conventional speaker unit not having the sheet
member 6 is compared, the directivity patterns in the horizontal direction are largely different
from each other. Although the speaker unit according to the present embodiment has less noise
and high sound quality than the conventional speaker unit, and has a good sense of sound field in
the high frequency range, the superiority in hearing is clear. there were.
[0025]
As mentioned above, although a suitable example of this embodiment was explained, sheet
member 6 is good also as a form as shown, for example in Drawing 3 (a)-(e) not only in a form
like Drawing 2.
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[0026]
Furthermore, although the speaker unit according to the present embodiment has been described
as a dome-shaped speaker in the above example, the present invention relates to a flat type
speaker in which a part of the diaphragm faces the tip surface of the pole piece 24 or The
present invention can also be applied to a cone type speaker having a center cap corresponding
to the tip surface.
[0027]
FIG. 4 shows an example applied to a cone type speaker.
In FIG. 4, the same reference numerals are given to parts having the same structure and function
as the dome-shaped speaker shown in FIG. 1, and the detailed description will be omitted.
[0028]
Here, the cone type speaker shown in FIG. 4 is a full range type or woofer, and its diaphragm 5 is
made of paper, wood, or synthetic resin such as polypropylene or polyester, aluminum or other
metal, or chemical fiber, etc. A circular central hole 5a communicating with the voice coil 3 is
formed in an inner central portion which is of a cone shape and joined to the voice coil 3.
Further, the outer periphery of the cone-shaped diaphragm 5 on the large diameter side is
supported by the frame 1 via an edge 7 that allows the diaphragm 5 to move in the front-rear
direction.
[0029]
Further, at the center of the diaphragm 5, a center cap 8 covering the center hole 5a is mounted
facing the upper end surface of the pole piece 24.
The center cap 8 is a dome-shaped member larger than the center hole 5a of the diaphragm 5,
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and is formed of paper, wood, metal, or a synthetic resin such as propylene or polyester like the
diaphragm 5, and the outer periphery is While being fixed to the diaphragm 5 with an adhesive,
the tip of the voice coil 3 is also bonded to the center cap 8. In the configuration of FIG. 4, the
upper end surface of the pole piece 24 is an opposing surface opposed to the back surface of the
diaphragm 5 and the center cap 8.
[0030]
The center cap 8 has a dustproof function to prevent dust from invading the magnetic circuit 2,
and the center cap 8 itself also vibrates along with the diaphragm 5 to affect the acoustic
characteristics. In particular, when the center cap 8 vibrates in the back and forth direction, the
sound radiated to the back side (the rear where the pole piece 24 is located) is reflected to the
pole piece 24 to generate echo sound, or the pole piece 24 resonates. It generates resonance
noise. For this reason, also in such a speaker unit, the sheet member 6 as described above is fixed
to the upper end surface of the pole piece 24 in the same manner as in the above example, with
an adhesive or the like.
[0031]
Therefore, it is possible to spread the sound in the radial direction (up and down, left and right
direction) of the pole piece 24 and to expand the sound field in the same direction while
suppressing the resonance sound and echo sound by the pole piece 24 even with the cone type
speaker.
[0032]
DESCRIPTION OF SYMBOLS 2 Magnetic circuit 24 pole piece 3 voice coil 31 coil bobbin 32
winding part 5 diaphragm 5a center hole 6 sheet member 63 cutout part 8 center cap
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