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JP2015095667

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DESCRIPTION JP2015095667
PROBLEM TO BE SOLVED: To provide a dynamic headphone unit that suppresses vibration and
resonance of acoustic resistance and prevents deterioration of frequency response and distortion
factor by applying stress to acoustic resistance. SOLUTION: A diaphragm 13 having a voice coil
133, a magnetic circuit 17 having a magnetic gap in which the voice coil 133 is disposed, a
magnetic circuit 17 and the diaphragm 13 are supported and opposed to the diaphragm 13. And
the unit frame 14 in which the acoustic resistance (11, 12) is disposed in the formed sound hole
(15, 16), and the acoustic resistance (11, 12) is stressed by the elastic members (21, 22) Is
added. [Selected figure] Figure 1
Dynamic headphone unit and dynamic headphone
[0001]
The present invention relates to a dynamic headphone unit and a dynamic headphone.
[0002]
In the dynamic headphone unit, a magnetic circuit is formed by a permanent magnet, a pole
piece provided on one pole side of the permanent magnet, and a yoke provided on the other pole
side of the permanent magnet.
A voice coil vibratably supported via a diaphragm is disposed in a magnetic gap formed in the
magnetic circuit. When a current corresponding to the voice signal is supplied to the voice coil,
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the voice coil vibrates according to the current by the action of the magnetic field generated by
the current and the magnetic field in the magnetic gap, and the diaphragm vibrates accordingly.
Sound is output. In such a dynamic headphone unit, an acoustic resistance is used to flatten the
frequency response to the input signal (see, for example, Patent Document 1).
[0003]
A conventionally known dynamic headphone unit will be described with reference to FIG. FIG. 3
is a cross-sectional view showing an example of the structure of a conventional dynamic
headphone unit 100. As shown in FIG. The dynamic headphone unit 100 has a diaphragm 13, a
unit frame 14, and a magnetic circuit 17 as a basic configuration.
[0004]
The diaphragm 13 has a center dome 131 and a sub dome 132 continuously provided around
the center dome 131, and a voice coil 133 is integrally attached to the boundary portion between
the center dome 131 and the sub dome 132 by an adhesive or the like. It is done.
[0005]
The magnetic circuit 17 includes a permanent magnet 171, a center pole piece 172, and a yoke
173.
The permanent magnet 171 is a magnet in which a disc-like metal is magnetized in the thickness
direction. The center pole piece 172 and the yoke 173 are separate magnetic bodies, and the
center pole piece 172 disposed on one pole side of the permanent magnet 171 and the other
pole side of the permanent magnet 171 A magnetic gap is formed between the plate-like yoke
173 and the plate-like yoke 173.
[0006]
The unit frame 14 is a disc made of synthetic resin, and supports the magnetic circuit 17 in a
hole formed in the central portion thereof. Further, the peripheral portion of the unit frame 14
supports the outer end portion of the sub dome 132 of the diaphragm 13 so that the voice coil
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133 can vibrate in the magnetic gap.
[0007]
A dynamic headphone provided with the dynamic headphone unit 100 includes a baffle plate
(not shown), a headphone case (ear cup), an ear pad, and a headband. The baffle plate is a diskshaped plate for fixing the dynamic headphone unit 100. The headphone case is attached to the
back side of the baffle plate on the back side (right side in FIG. 3) of the dynamic headphone unit
100. The space formed by the baffle plate, the dynamic headphone unit 100 and the housing
becomes a back air chamber. The ear pads are disposed on the front side of the baffle plate and
abut on the side of the user.
[0008]
A first sound hole 15 is formed in the peripheral portion of the unit frame 14 in order to
acoustically connect the back side of the sub dome 132 of the diaphragm 13 and the back air
chamber (not shown). A plurality of first sound holes 15 are concentrically formed at the
peripheral portion of the unit frame 14. A second sound hole 16 is formed in the central portion
of the magnetic circuit 17 in order to acoustically connect the back side of the center dome 131
of the diaphragm 13 and the back air chamber (not shown).
[0009]
The first acoustic resistor 11 is attached to the back side of the first sound hole 15. The first
sound hole 15 is covered by the first acoustic resistor 11. In addition, the second acoustic
resistor 12 is attached to the back side of the second sound hole 16. The second acoustic
resistance 12 covers the second sound hole 16. By using the acoustic resistance material in this
manner, the frequency response to the input signal in the dynamic headphone unit 100 can be
made flat.
[0010]
When an input signal of 1 mW is applied to the conventional dynamic headphone unit 100
having the above configuration, the vibration of the diaphragm 13 by this input signal causes
approximately 100 dB (2 Pa) in the front space and the rear space of the diaphragm 13. Sound
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pressure occurs.
[0011]
Assuming that the dynamic headphone unit 100 is used, the user's ear is in front of the
diaphragm 13.
The volume of the space formed by the ear, the ear pad, and the diaphragm 13 is about 10 times
larger than the volume of the space behind the diaphragm 13. In other words, the volume of the
space formed by the diaphragm 13 and the first and second acoustic resistors 11 and 12 is about
1/10 of the volume of the space in front of the diaphragm 13.
[0012]
The diaphragm 13 moves in the same manner forward and backward. The sound pressure in the
rear space of the diaphragm 13 generated by the 1 mW input signal to the dynamic headphone
unit 100 is about 120 dB (20 Pa) or more.
[0013]
The sound pressure as described above increases in accordance with the level of the input signal
to the dynamic headphone unit 100. For example, when the level of the input signal exceeds 32
mW, the sound pressure in the space behind the diaphragm 13 exceeds 150 dB. Such a large
sound pressure is applied to the first acoustic resistance 11 and the second acoustic resistance
12.
[0014]
The first acoustic resistor 11 is for applying a resistive load to the entire sub dome 132.
Therefore, the effective area of the first acoustic resistor 11 needs to be close to the area of the
sub dome 132. That is, the opening area of the first sound hole 15 needs to be increased. In
addition, the second acoustic resistor 12 applies a resistive load to the entire center dome 131.
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Therefore, the effective area of the second acoustic resistance 12 also needs to be close to the
area of the center dome 131. That is, the opening area of the second sound hole 16 needs to be
increased. However, when the effective area of the first acoustic resistor 11 or the second
acoustic resistor 12 is increased, the first acoustic resistor 11 or the second acoustic resistor 12
easily vibrates due to the large sound pressure being added thereto.
[0015]
JP, 2011-87098, A
[0016]
Since the sound resistant material is made of a mesh or non-woven fabric, it vibrates easily with a
large sound pressure as described above, and resonates at a specific frequency determined by
the mass and stiffness of the sound resistant material. .
Such vibration or resonance of the acoustic resistance material causes the frequency response
and distortion rate of the dynamic headphone unit 100 to deteriorate, and causes the sound
quality of the output of the dynamic headphone unit 100 to deteriorate.
[0017]
Therefore, an object of the present invention is to provide a dynamic headphone unit that
suppresses vibration and resonance of acoustic resistance and prevents deterioration of
frequency response and distortion factor.
[0018]
The present invention supports a diaphragm having a voice coil, a magnetic circuit having a
magnetic gap in which the voice coil is disposed, and the sound circuit formed to support the
magnetic circuit and the diaphragm and to be opposed to the diaphragm. And a unit frame in
which an acoustic resistance is disposed, wherein the acoustic resistance is characterized by
being stressed by an elastic member.
[0019]
According to the present invention, it is possible to suppress the vibration and resonance of the
acoustic resistance and to prevent the deterioration of the frequency response and the distortion
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factor.
[0020]
It is a sectional view showing an example of an embodiment of a dynamic headphone unit
concerning the present invention.
It is the expanded sectional view which expanded the characteristic part of the said dynamic
headphone unit.
It is sectional drawing which shows the example of the conventional dynamic headphone unit.
[0021]
Hereinafter, embodiments of a dynamic headphone unit according to the present invention will
be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an example of a dynamic headphone unit 10 according
to the present embodiment. The dynamic headphone unit 10 includes, as a basic configuration, a
configuration common to the conventional example. In the description of the present
embodiment, the same components as those of the conventional example are denoted by the
same reference numerals.
[0022]
As shown in FIG. 1, the dynamic headphone unit 10 includes a diaphragm 13, a unit frame 14,
and a magnetic circuit 17.
[0023]
The diaphragm 13 has a center dome 131 and a sub dome 132 continuously provided around
the center dome 131, and a voice coil 133 is integrally attached with an adhesive or the like at a
boundary portion between the center dome 131 and the sub dome 132. ing.
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[0024]
The magnetic circuit 17 includes a permanent magnet 171, a center pole piece 172, and a yoke
173.
The permanent magnet 171 is a magnet in which a disc-like metal is magnetized in the thickness
direction.
The center pole piece 172 and the yoke 173 are separate magnetic bodies. A magnetic gap is
formed between the center pole piece 172 disposed on one pole side of the permanent magnet
171 and the plate-like yoke 173 disposed on the other pole side of the permanent magnet 171.
[0025]
The unit frame 14 is a disc made of synthetic resin, and supports the magnetic circuit 17 in a
hole formed in the central portion thereof. The peripheral edge of the unit frame 14 supports the
outer end of the sub dome 132 of the diaphragm 13 so that the voice coil 133 can vibrate in the
magnetic gap as described above.
[0026]
A dynamic headphone including the dynamic headphone unit 10 includes a baffle plate (not
shown), a headphone case (ear cup), an ear pad, and a headband. The baffle plate is a diskshaped plate for fixing the dynamic headphone unit 10. The headphone casing is attached to the
back side of the baffle plate on the back side (right side in FIG. 1) of the dynamic headphone unit
10. A space formed by the baffle plate, the dynamic headphone unit 10, and the housing
becomes a back air chamber. The ear pads are disposed on the front side of the baffle plate and
abut on the side of the user.
[0027]
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A first sound hole 15 is formed in the peripheral portion of the unit frame 14. A plurality of first
sound holes 15 are concentrically formed at the peripheral portion of the unit frame 14 to face
the sub dome 132 of the diaphragm 13, and the back side of the sub dome 132 and the back air
chamber (not shown) are acoustically Connected A second sound hole 16 is formed in the central
portion of the magnetic circuit 17. The second sound hole 16 faces the center dome 131 of the
diaphragm 13 to acoustically connect the back side of the center dome 131 and the back air
chamber (not shown).
[0028]
The first acoustic resistor 11 is disposed on the back side (right side in FIG. 1) of the first sound
hole 15. In addition, a second acoustic resistor 12 is disposed on the back side of the second
sound hole 16. Each of the first acoustic resistance 11 and the second acoustic resistance 12 is a
material that transmits sound, and is, for example, a net or non-woven fabric.
[0029]
A first elastic member 21 and a first pressing member 23 for pressing the first elastic member
21 against the first acoustic resistor 11 are disposed on the back side (right side in FIG. 1) of the
first acoustic resistor 11. . The first elastic member 21 is, for example, a sponge, made of a
material that transmits sound and has elasticity. The first elastic member 21 has the same shape
as the outer edge portion shape (peripheral portion shape) of the unit frame 14.
[0030]
Here, the first elastic member 21 and the first pressing member 23 will be described in detail.
FIG. 2 is an enlarged cross-sectional view of a region A in FIG. As shown in FIG. 2, the first elastic
member 21 is disposed on the back side of the first acoustic resistor 11, and the first pressing
member 23 is disposed on the back side of the first elastic member 21.
[0031]
When the first elastic member 21 is abutted against the back surface side of the first acoustic
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resistor 11 and the first pressing member 23 is pressed to the unit frame 14 side, the first elastic
member 21 faces the diaphragm 13 (direction of the sub dome 132). It will be crushed. Since the
first elastic member 21 is made of a material such as sponge, after being crushed once by the
first pressing member 23, the first elastic member 21 expands in an attempt to return to the
original state.
[0032]
The first pressing member 23 has, for example, the same shape as the outer edge portion shape
(peripheral portion shape) of the unit frame 14 and is fixed to the unit frame 14 by a fastening
member (screw) or the like not shown. A hole is formed in the first pressing member 23, and the
hole is disposed at a position facing the first sound hole 15 in a state where the unit frame 14
and the first pressing member 23 are fixed. That is, the space on the back side of the sub dome
132 is in communication with the back air chamber (not shown) via the first acoustic resistance
11, the first elastic member 21, and the first pressing member 23.
[0033]
When the first elastic member 21 pressed to the unit frame 14 side by the first pressing member
23 expands, the first acoustic resistance 11 is pushed out to the sub dome 132 side. That is, the
first acoustic resistance 11 is in a state of being pressed against the unit frame 14 by the first
elastic member 21 and the first acoustic resistance 11 of the portion corresponding to the first
sound hole 15 swells toward the diaphragm 13 and is deformed. Do. The stress caused by this
deformation makes it difficult for the first acoustic resistor 11 to resonate even when a large
pressure is applied due to the vibration of the sub dome 132, thereby suppressing the vibration.
[0034]
That is, the dynamic headphone unit 10 prevents the deterioration of the frequency response and
the distortion factor by arranging the first elastic member 21 on the back side of the first
acoustic resistance 11 to apply stress to the first acoustic resistance 11. be able to.
[0035]
Return to FIG.
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A second elastic member 22 is disposed in the second sound hole 16 provided in the central
portion of the magnetic circuit 17. A second pressing member 24 for securing the second elastic
member 22 in the second sound hole 16 is attached to the opening on the center dome 131 side
of the second sound hole 16.
[0036]
The second elastic member 22 is, for example, a sponge, made of a material that transmits sound
and has elasticity. The second elastic member 22 has the same shape as the second sound hole
16.
[0037]
When the second elastic member 22 is inserted into the second sound hole 16 and pushed in, the
second elastic member 22 is crushed once. Thereafter, before the second elastic member 22 is
restored, the insertion port of the second elastic member 22 is closed by the second pressing
member 24. Then, the second pressing member 24 and the second acoustic resistance 12 expand
outward of the magnetic circuit 17 by the restoring force of the second elastic member 22. That
is, stress is applied to the second acoustic resistance 12 by the second elastic member 22. The
second pressing member 24 is a material that passes the same sound as the first acoustic resistor
11 and the second acoustic resistor 12 and is, for example, a net or a non-woven fabric. The
second acoustic resistance 12 and the second pressing member 24 may be fixed to the outer
surface of the magnetic circuit 17 using an adhesive such as double-sided tape.
[0038]
Due to this stress, the second acoustic resistance 12 is less likely to resonate even when a large
pressure is applied due to the vibration of the center dome 131, and the vibration can be
suppressed. That is, the dynamic headphone unit 10 prevents the deterioration of the frequency
response and the distortion factor by arranging the second elastic member 22 on the front side
of the second acoustic resistance 12 to apply a stress to the second acoustic resistance 12. be
able to. A space on the back side of the center dome 131 is in communication with a back air
chamber (not shown) via the second pressing member 24, the second elastic member 22, and the
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second acoustic resistor 12.
[0039]
According to the dynamic headphone unit 10 described above, by applying stress to the acoustic
resistance material, it is possible to suppress the vibration and resonance of the acoustic
resistance material and to prevent the deterioration of the frequency response and the distortion
factor and the deterioration of the sound quality.
[0040]
10 dynamic headphone unit 11 first acoustic resistance 12 second acoustic resistance 13
diaphragm 14 unit frame 15 first sound hole 16 second sound hole 21 first elastic member 22
second elastic member 23 first holding member 24 second holding member
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