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DESCRIPTION JP2010011328

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DESCRIPTION JP2010011328
An object of the present invention is to obtain a headphone capable of maintaining the acoustic
characteristics required for the headphone by using a configuration unique to the headphone in
preventing generation of noise caused by extraneous electromagnetic waves. SOLUTION: A
headphone unit 1 provided with a diaphragm 6 driven by an audio signal and emitting an
acoustic wave, and a circuit board 12 provided with a hole 121 disposed behind the headphone
unit 1 and communicating with an acoustic hole 22 of the headphone unit 1 And a shield /
sound-resistant material 16 disposed behind the headphone unit 1 together with the circuit
board 12. The shield and sound resistance material 16 is made of a conductive cloth. The resin
baffle plate 10 to which the headphone unit 1 and the circuit board 12 are fixed is provided, and
a conductive layer is formed on the surface of the baffle plate 10. [Selected figure] Figure 1
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[0001]
The present invention relates to a headphone, and is particularly characterized in the shield
structure for preventing the generation of noise due to electromagnetic waves and the
configuration of an acoustic resistance material for improving frequency response.
[0002]
A typical headphone comprises, as a main component, a headphone unit having a similar
structure to that of a dynamic speaker.
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In the case of headphones with an ear-cover type, a headphone unit is generally attached to the
baffle plate, an ear pad is attached to the front side of the baffle plate, and a housing that covers
the headphone unit is attached to the back side of the baffle plate. .
[0003]
FIG. 2 shows an example of a conventional earbud headphone. In FIG. 2, reference numeral 1
indicates a headphone unit. The headphone unit 1 is based on the unit frame 2 and has a
magnetic circuit component, a diaphragm 6 and a voice coil 7 as main components. The magnetic
circuit component includes a dish-like yoke 3, a magnet 4 fixed to the inner bottom of the yoke 3,
and a pole piece 5 fixed to the front end face of the magnet 4. A cylindrical gap is formed over
the entire circumference between the inner peripheral surface of the front end portion of the
yoke 3 and the outer peripheral surface of the pole piece 5, and the gap is a magnetic flux
generated by passing a magnetic flux from the magnet 4. It is a gap.
[0004]
An outer periphery of the yoke 3 is fitted to a cylindrical portion 21 formed at a central portion
of the unit frame 2 and integrated with the unit frame 2. The diaphragm 6 comprises a main
dome at a central portion and a sub dome surrounding the periphery of the main dome, and the
outer peripheral edge of the sub dome is fixed to the front outer peripheral edge of the unit
frame 2. The diaphragm 6 is, for example, a thin plate-like component made of resin, and can
vibrate in the front-rear direction with the outer peripheral edge fixed to the unit frame 2 as a
fulcrum. The front end of the voice coil 7 is fixed to the back side of the diaphragm 6 along the
boundary between the main dome and the sub dome. The voice coil 7 is a component in which a
thin conductive wire is wound in a cylindrical shape, and is disposed in the magnetic gap, and
can move in the front-rear direction without touching the yoke 3 or the pole piece 5 together
with the diaphragm 6 ing.
[0005]
As apparent from the configuration described above, since the voice coil 7 is disposed in the
magnetic gap, when a voice signal is input to the voice coil 7, the current according to the voice
signal and the magnetic flux in the magnetic gap The electromagnetic force moves the voice coil
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2
7 in the front-rear direction. Since the diaphragm 6 vibrates back and forth together with the
voice coil 7, a sound wave according to the audio signal is emitted from the diaphragm 6.
[0006]
The unit frame 2 of the headphone unit 1 is fitted and fixed in a hole provided at the center of
the baffle plate 10. An ear pad 13 is fixed to the front outer peripheral edge of the baffle plate
10, and a bowl-shaped housing 14 is fixed to the back side of the baffle plate 10. A space is
formed between the diaphragm 6 and the magnetic circuit component, and assuming that this
space is a closed space, the air in this space acts as a spring and the diaphragm 6 serves as an
audio signal. You will not be able to vibrate faithfully. Therefore, an appropriate number of
acoustic holes 22 are formed in the unit frame 2 to communicate the internal space of the
headphone unit 1 with the space behind the headphone unit 1. Further, in order to provide the
diaphragm 6 with an appropriate damping characteristic to improve the frequency response, the
acoustic resistance material 25 is attached to the unit frame 2 to cover the acoustic hole 22. As
the acoustic resistance material 25, a material such as an open-celled sponge, glass wool, a nonwoven fabric, or the like that provides appropriate resistance to the flow of air is selected.
[0007]
A jetty 11 is formed on the back side of the baffle plate 10 so as to surround the mounting
portion of the headphone unit 1 on the outer peripheral side of the mounting portion of the
headphone unit 1. The circuit board 12 is overlapped and fixed to the tip of the jetty 11 (right
end in FIG. 2). A hole is formed in the central portion of the circuit board 12, and the hole
communicates with the acoustic hole 22 of the unit frame 2. The acoustic resistance material 20
is overlapped and fixed to the circuit board 12, and the hole at the central portion of the circuit
board 12 is covered with the acoustic resistance material 20. In order to improve the frequency
response of the headphone unit 1, the acoustic resistance value of the acoustic resistance
material 20 is set to an appropriate value.
[0008]
A protector 8 is disposed in front of the diaphragm 6 so that the diaphragm 6 can not be touched
from the outside. The protector 8 has substantially the same shape as the shape of the
diaphragm 6, and the outer peripheral edge portion is fixed to the front surface of the baffle
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plate 10 with a predetermined distance from the front surface of the diaphragm 6. The protector
8 is provided with an appropriate number of holes in order to pass the sound wave from the
diaphragm 6. The headphones configured as described above are usually coupled by a headband
as two pairs, and stereo headphones are configured.
[0009]
The headphone as described above is desired to be as lightweight as possible because the user
wears it on the head and uses it. Therefore, plastic parts are more often used than component
parts. For example, in the conventional example shown in FIG. 2, the baffle plate 10, the unit
frame 2, the protector 8 and the like are often made of plastic. Therefore, the structure is such
that electromagnetic waves from the outside can easily penetrate the plastic parts.
[0010]
In the case of general headphones, problems caused by the penetration of electromagnetic waves
are not very noticeable, but in noise canceling headphones, since electronic circuits for noise
cancellation are mounted, the electromagnetic waves that enter are detected by electronic circuit
components, Generate noise. In particular, with the widespread use of mobile phones in recent
years, mobile phones are often used near headphones, and when electromagnetic waves radiated
from nearby mobile phones intrude into headphones, the level of noise generated by detection by
electronic circuits is Get higher. In the case of headphones, since electromagnetic waves, that is,
noise caused by high frequency current directly enter the ear as sound waves, if the noise level is
high, there is a concern that the user may feel uncomfortable.
[0011]
Therefore, in the present invention, in order to prevent generation of noise caused by
electromagnetic waves in headphones, the present invention is devised so that electromagnetic
waves entering from the outside can be effectively blocked. However, in various electronic
devices, in order to shield electromagnetic waves, as described below, devices specific to the
respective electronic devices have been made.
[0012]
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In Patent Document 1, in an electronic device such as a portable computer, a concave portion for
accommodating a hard disk drive (hereinafter referred to as "HDD") is provided, a shield layer is
formed on the inner surface of the concave portion, and The shield structure of the HDD is
described, in which the conductive member is provided to conduct and the HDD cover whose
inner surface is provided with the shield layer is covered with the HDD cover.
[0013]
Patent Document 2 includes a substrate for mounting an electronic component and a shield case
for shielding the electronic component in an electronic device such as a mobile phone, and the
shield case covers the electronic component and is attached to the mounting surface and
mounted on the mounting surface. And a shield cover attached to the shield base so as to cover
the first opening, the shield cover being inserted into the first opening. There is described a
shield structure provided with a pressing portion that presses the electronic component to the
substrate side.
[0014]
Both the invention described in Patent Document 1 and the invention described in Patent
Document 2 shield the electronic component specific to each electronic device with a unique
shield structure based on the configuration specific to the configuration of the individual
electronic device.
[0015]
JP 2007-328531 A JP JP 2007-299814 A
[0016]
An object of the present invention is to provide a headphone capable of maintaining the acoustic
characteristics required for the headphone by utilizing a configuration unique to the headphone
in preventing the generation of noise caused by an external electromagnetic wave. Do.
[0017]
A headphone according to the present invention comprises a headphone unit provided with a
diaphragm driven by an audio signal to emit sound waves, a circuit board provided behind the
headphone unit and provided with a hole communicating with an acoustic hole of the headphone
unit And a shield / acoustic resistance material disposed behind the headphone unit.
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[0018]
According to the headphone according to the present invention, since the shield and acoustic
resistance material is disposed to cover the circuit board together with the headphone unit,
electromagnetic waves from the outside are prevented from entering the circuit board, and the
electronic circuit of the circuit board is used. It is possible to prevent the problem that noise is
generated by detecting the electromagnetic wave.
The shield and acoustic resistance material also functions as an acoustic resistance, so it is
possible to adjust the acoustic characteristics of the headphones, and despite the relatively
simple configuration, it is possible to obtain a great effect as the headphones .
[0019]
The shield and sound resistance material may be made of a conductive cloth.
The shield effect can be further enhanced by providing a resin baffle plate on which the
headphone unit and the circuit board are fixed and forming a conductive layer on the surface of
the baffle plate.
The shielding and acoustic resistance material can be further enhanced in the shielding effect if it
is conducted to the conductive layer on the surface of the baffle plate.
[0020]
Hereinafter, with reference to FIG. 1, an embodiment of a headphone according to the present
invention will be described.
The same reference numerals as in the prior art shown in FIG.
In FIG. 1, reference numeral 1 indicates a headphone unit.
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The headphone unit 1 is based on a unit frame 2 and has a magnetic circuit component, a
diaphragm 6 and a voice coil 7 as main components. The above-mentioned magnetic circuit
constituent members are a disk-shaped yoke 3, a disk-shaped magnet 4 fixed to the inner bottom
surface of the yoke 3, and a disk-shaped pole piece fixed to the front end surface of the magnet
4. It will be equipped with five. A cylindrical gap is formed over the entire circumference between
the inner peripheral surface of the front end (left end in FIG. 1) of the yoke 3 and the outer
peripheral surface of the pole piece 5. Becomes a magnetic gap. The material of the unit frame 2
may be metal, and resin may be used for weight reduction.
[0021]
An outer periphery of the yoke 3 is fitted to a cylindrical portion 21 formed at a central portion
of the unit frame 2 and integrated with the unit frame 2. The diaphragm 6 comprises a main
dome at a central portion and a sub dome surrounding the periphery of the main dome, and the
outer peripheral edge of the sub dome is fixed to the front outer peripheral edge of the unit
frame 2. The diaphragm 6 is, for example, a thin plate-like component made of resin, and can
vibrate in the front-rear direction with the outer peripheral edge fixed to the unit frame 2 as a
fulcrum. The front end of the voice coil 7 is fixed to the back side of the diaphragm 6 along the
boundary between the main dome and the sub dome. The voice coil 7 is a component in which a
thin conductive wire is wound in a cylindrical shape, and is disposed in the magnetic gap, and
can move in the front-rear direction without touching the yoke 3 or the pole piece 5 together
with the diaphragm 6 ing.
[0022]
The unit frame 2 of the headphone unit 1 is fitted and fixed in a hole provided at the center of
the baffle plate 10. An ear pad 13 is fixed to the front outer peripheral edge of the baffle plate
10, and a bowl-shaped housing 14 is fixed to the back side of the baffle plate 10. An internal
space is formed between the diaphragm 6 and the magnetic circuit component. An appropriate
number of acoustic holes 22 are formed in the unit frame 2, and the internal space of the
headphone unit 1 and the space behind the headphone unit 1 are in communication via the
acoustic holes 22. Further, in order to provide the diaphragm 6 with an appropriate damping
characteristic to improve the frequency response, the acoustic resistance material 25 is attached
to the unit frame 2 to cover the acoustic hole 22. As the acoustic resistance material 25, a
material such as an open-celled sponge, glass wool, a non-woven fabric, or the like that provides
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appropriate resistance to the flow of air is selected.
[0023]
A jetty 11 is formed on the back side of the baffle plate 10 so as to surround the mounting
portion of the headphone unit 1 on the outer peripheral side of the mounting portion of the
headphone unit 1. The circuit board 12 is overlapped and fixed to the front end (right end in FIG.
1) of the jetty 11. A hole 121 is formed in the central portion of the circuit board 12, and the
hole 121 communicates with the acoustic hole 22 of the unit frame 2.
[0024]
Since the voice coil 7 is disposed in the magnetic gap, when a voice signal is input to the voice
coil 7, the voice coil 7 is moved in the front-back direction by the electromagnetic force of the
current according to the voice signal and the magnetic flux in the magnetic gap. Move to Since
the diaphragm 6 vibrates back and forth together with the voice coil 7, a sound wave according
to the audio signal is emitted from the diaphragm 6.
[0025]
In the conventional example shown in FIG. 2 described above, the acoustic resistance material 20
is superimposed on and fixed to the circuit board 12, and the hole 121 in the central portion of
the circuit board 12 is covered with the acoustic resistance material 20. The acoustic resistance
value of the acoustic resistance material 20 has been set to an appropriate value in order to
improve the In the embodiment of the present invention shown in FIG. 1, a shield and acoustic
resistance material 16 is disposed in place of the acoustic resistance material 20, and the shield
and acoustic resistance material 16 covers the back of the headphone unit 1 together with the
circuit board 12. . As the shield / acoustic resistance material 16, a material provided with a
shield effect for blocking an electromagnetic wave and an acoustic resistance effect which is an
appropriate resistance to the transmission of a sound wave is selected. A conductive cloth is a
material suitable as the shielding and acoustic resistance material 16, and in the embodiment
shown in FIG. 1, a conductive cloth "Sui-78-5050T" manufactured by Seiren Co., Ltd. was used.
[0026]
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In order to reduce the weight of the headphones, the baffle plate 10 is made of resin, and
electromagnetic waves can pass through the baffle plate 10. Therefore, a conductive layer is
formed on the surface of the baffle plate 10 by a method such as plating. The shield and acoustic
resistance material 16 has an area sufficiently larger than that of the circuit board 12, is bent
toward the circuit board 12 along the outer peripheral edge of the circuit board 12, and is
pressed against the inner circumferential surface of the housing 14. The outer peripheral edge
portion of the shield and acoustic resistance material 16 is in contact with the conductive layer
on the surface of the baffle plate 10 and passes. The conductive layer of the baffle plate 10 is
grounded, for example, by being connected to a ground electrode.
[0027]
As described above, since the back side of the headphone unit 1 is covered with the circuit board
12 with the shield and acoustic resistance material 16, the electromagnetic wave that is going to
intrude from the back side of the headphone is blocked by the shield and acoustic resistance
material 16 . This shielding effect is particularly effective in active noise cancellation
headphones. The active noise cancellation headphone has a microphone for detecting
environmental noise and a cancellation signal generation circuit for canceling out the
environmental noise detected by the microphone, and the circuit elements constituting the
cancellation signal generation circuit are mounted on the circuit board 12 Ru. When an
electromagnetic wave intrudes into this circuit element, it is detected and generates noise.
However, according to the embodiment shown in FIG. 1, the occurrence of noise can be
prevented by blocking the penetration of the electromagnetic wave into the circuit board 12 by
the shield / acoustic resistance material 16. The shielding and acoustic resistance material 16
passes through the conductive layer on the surface of the baffle plate 10 to further enhance the
shielding effect. Since the shield and acoustic resistance material 16 also has an effect as an
acoustic resistance material, the acoustic characteristics of the headphones can be adjusted
without separately providing the acoustic resistance material.
[0028]
In FIG. 1, a protector 8 is disposed in front of the diaphragm 6 so that the diaphragm 6 can not
be touched from the outside. The protector 8 has substantially the same shape as the shape of
the diaphragm 6, and the outer peripheral edge portion is fixed to the front surface of the baffle
plate 10 with a predetermined distance from the front surface of the diaphragm 6. The protector
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8 is provided with an appropriate number of holes in order to pass the sound wave from the
diaphragm 6. The protector 8 is made of resin, and a conductive layer is formed on the surface of
the protector 8. The conductive layer of the protector 8 passes through the conductive layer on
the surface of the baffle plate 10. The baffle plate 10 and the protector 8 may be molded of resin
as an integral part, and a conductive layer may be formed on the surface.
[0029]
The electromagnetic wave which is going to intrude from the front side of the headphone unit 1
is blocked by the conductive layer on the surface of the protector 8, and generation of noise due
to the electromagnetic wave can be prevented. By passing the conductive layer of the protector 8
and the conductive layer on the surface of the baffle plate 10, the shielding effect can be further
enhanced. The headphones configured as described above are usually coupled by a headband as
two pairs, and stereo headphones are configured.
[0030]
Instead of the conductive layer formed on the surface of the protector 8 in the above
embodiment, a shield and acoustic resistance material may be attached to the surface of the
protector 8. Since this shield and sound resistant material is a member that may come in contact
with the user's ear or the like, it is preferable to use, for example, a sponge-like shield and sound
resistance material so as not to impair the feel. Furthermore, if a conductive cloth or a conductive
layer is formed on the inner and outer surfaces of the ear pad 13 constituting the front side
cavity when using headphones, the shield with the human body side is also ensured.
[0031]
It is a longitudinal cross-sectional view which shows the Example of the headphone which
concerns on this invention. It is a longitudinal cross-sectional view which shows the example of
the conventional headphone.
Explanation of sign
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[0032]
Reference Signs List 1 headphone unit 2 unit frame 3 yoke 4 magnet 5 pole piece 6 diaphragm 7
voice coil 8 protector 10 baffle plate 11 jetty 12 circuit board 13 ear pad 14 housing 16 shield
and acoustic resistance material 22 acoustic hole
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