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DESCRIPTION JP2018007220

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DESCRIPTION JP2018007220
Abstract: To provide a tweeter unit capable of obtaining a small-diameter sound volume of a
sufficiently high frequency band, and an earphone using the tweeter unit. SOLUTION: A vibrating
plate 21 is vibrated by a piezoelectric element or MEMS, and a sound is reflected by a reflecting
material 25 and directed in the sound emission axis direction. By tilting the diaphragm 21 with
respect to the sound emission axis, the volume of high sound can be increased. The tweeter unit
2 is provided. In addition, an earphone using the tweeter unit 2 and the woofer unit 3 is
provided. [Selected figure] Figure 2
Tweeter unit and earphone
[0001]
The present invention relates to a tweeter unit used for an earphone, and an earphone using the
tweeter unit.
[0002]
In recent years, digital audio data of high sampling frequency has become widespread.
Along with this, in not only the speaker but also the earphone, an earphone with improved sound
quality in a high frequency band has appeared.
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[0003]
The sound quality improvement of the high frequency band in the earphone is not easy. The
structure using a driver with balanced armature system contributes to reducing the size and
weight of the earphone, but because there is a limit to the bandwidth of the frequency, multiple
drivers such as for low frequency and high frequency are required. The structure inside the
earphone becomes complicated and expensive. Also, in an earphone using a dynamic type driver,
the area of the diaphragm determines the volume, and the diaphragm is disposed perpendicular
to the sound guiding axis from the earphone to the ear, so the earphone with a restricted
diameter of the ear plug is sufficient I can not get the volume.
[0004]
Recently, for example, as disclosed in Patent Document 1, an earphone using a piezoelectric
driver excellent in reproduction in a high frequency band has come to be seen. However, even in
the piezoelectric driver, the volume is determined by the area of the diaphragm to which the
piezoelectric element is attached, and therefore, in the earphone in which the diameter of the ear
plug is restricted, a sufficient volume can not be obtained.
[0005]
Utility model registration 3 1984 75
[0006]
An object of the present invention is to provide a tweeter unit capable of obtaining a sound
volume of a small diameter and a sufficiently high frequency band, and an earphone using the
tweeter unit.
Here, "tweeter unit" refers to a member that generates sound in a high frequency band based on
an electrical signal.
[0007]
The tweeter unit of the present invention comprises: a cylindrical main body having a sound
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emission hole at one end for emitting sound in the sound emission axis direction; a tweeter in
which a piezoelectric element is attached to a diaphragm and disposed in the main body; A
reflecting member for reflecting the sound emitted from the tweeter toward the sound output
hole, the area of the diaphragm being S1, a cross section perpendicular to the sound output axis
of the inner space of the main body, within the cross section When the cross-sectional area of the
cross section closest to the sound output hole among the existing diaphragms is S2, S1 、 (√2)
S2.
[0008]
According to this feature, the diaphragm can be oriented in a direction other than the direction
perpendicular to the sound emission axis direction by the effect of the reflector, and the shape of
the diaphragm is not restricted by the cross-sectional shape of the cylindrical main body .
The volume of the diaphragm can be obtained by increasing the area of the diaphragm, which
was conventionally equal to or less than S2, to S1. Although the value of S1 is preferably large, it
is assumed that S1 ((≧ 2) S2. The sound volume can be obtained by (倍 2) times or more
compared to the conventional method. The (と し た 2) times or more means that the diaphragm
on the main body on the square pole is inclined 45 degrees or more to the sound emission axis In
principle, it is
[0009]
The tweeter unit according to the present invention is characterized in that the main body is a
columnar pipe whose axial direction is the direction of the sound emission axis.
[0010]
According to this feature, the present invention can be applied to a columnar pipe similar to the
conventional method.
[0011]
In the tweeter unit according to the present invention, the reflecting member is a flat member
facing the inner space of the main body, and the normal direction of the plane is an angle
between the normal line of the diaphragm and the sound emission axis. And the direction of the
bisector of
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[0012]
According to this feature, the sound reflected by the reflector is emitted in the direction of the
sound emission axis.
[0013]
In the tweeter unit of the present invention, the reflecting member is a member having a
paraboloid shape facing the internal space of the main body, and the paraboloid of revolution has
a rotational axis in the normal direction of the diaphragm. A focal point is located at a center
position of the sound emission hole or at a position away from the position along the sound
emission axis and outside the main body.
[0014]
According to this feature, the sound reflected by the reflector is concentrated at the focal point.
If the focal point is placed on the eardrum side of the earphone, the sound reflected by the
reflector can be emitted toward the eardrum.
[0015]
The tweeter unit according to the present invention is characterized in that a wall surface of an
internal space of the main body constitutes the reflective material.
[0016]
According to this feature, the tweeter unit is configured to be reflected by the main body and not
provided with a separate reflector.
[0017]
The tweeter unit according to the present invention is characterized in that the normal line of the
diaphragm is inclined 45 degrees or more with respect to the sound emission axis.
[0018]
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According to this feature, the area of the vibrating plate can be increased by utilizing the
cylindrical length of the cylindrical main body.
Assuming that the main body has a quadrangular prism shape, an area of (√2) times or more (=
1 / sin (45 degrees) or more) is obtained as compared with the case where the diaphragm is
provided perpendicularly to the sound output axis.
[0019]
An earphone according to the present invention is characterized by including the tweeter unit
according to the present invention and a woofer unit.
[0020]
According to this feature, an earphone utilizing the tweeter unit of the present invention is
provided.
[0021]
The earphone according to the present invention comprises an earphone plug for transmitting
sound to the ear along the sound guiding axis, and the tweeter unit and the woofer unit are
disposed in parallel toward the sound guiding axis. It features.
[0022]
According to this feature, the sound of the tweeter unit and the woofer unit can both be emitted
along the sound introducing axis.
[0023]
The earphone according to the present invention includes an earphone plug for transmitting
sound, the tweeter unit and the woofer unit are disposed in series toward the sound introducing
axis, and the emitted sound of the woofer unit is of the tweeter unit. It is characterized in that it
is transmitted to the internal space of the main body from a hole opposed to the sound output
hole of the main body and emitted from the sound output hole.
[0024]
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This feature also makes it possible to emit both the tweeter unit and the woofer unit along the
sound transmission axis.
Since the tweeter unit and the woofer unit are arranged in series, the outer diameter of the
earphone can be reduced.
[0025]
The earphone according to the present invention is characterized in that the woofer unit
comprises a balun-store-type woofer.
[0026]
According to this feature, the outer diameter of the earphone can be reduced by the small
diameter balun-store type woofer.
[0027]
According to the tweeter unit of the present invention, a high-volume tweeter unit is provided
while having a small diameter.
[0028]
Further, according to the earphone of the present invention, an earphone having a large sound
volume in a high frequency band and good frequency characteristics while having a small
diameter can be provided.
[0029]
FIG. 1 is a diagram showing the configuration of a conventional earphone.
FIG. 2 is a view showing a configuration example of the tweeter unit.
Example 1 FIG. 3 is a view showing an example of the configuration of a tweeter unit.
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Second Embodiment FIG. 4 is a view showing a configuration example of a tweeter unit.
Third Embodiment FIG. 5 is a view showing a configuration example of a tweeter unit.
Fourth Embodiment FIG. 6 is a view showing a configuration example of a tweeter unit.
Example 5 FIG. 7 is a view showing an example of the configuration of an earphone.
Sixth Embodiment FIG. 8 is a view showing an example of a tweeter.
Sixth Embodiment FIG. 9 is a diagram showing frequency characteristics.
Sixth Embodiment FIG. 10 is a view showing a configuration example of an earphone.
Example 7 FIG. 11 is a diagram showing frequency characteristics.
Example 7 FIG. 12 is a view showing an example of the configuration of an earphone.
Example 8 FIG. 13 is a diagram showing frequency characteristics.
(Example 8)
[0030]
FIG. 1 is a diagram showing the configuration of a conventional earphone.
The earphone 1 is provided with a woofer 21 and a tweeter 31 in a housing 11. Although the
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woofer 21 and the tweeter 31 can be designed arbitrarily, the woofer 21 is described as a
dynamic system and the tweeter 31 is an electromagnetic system.
[0031]
The woofer 21 and the tweeter 31 vibrate in the direction indicated by the white arrow in the
drawing to generate compression waves in the air, and emit sound in the direction indicated by
the black arrow in the drawing. Here, although the volume of the tweeter 31 is in proportion to
the area of the diaphragm, the inside diameter R of the housing 11 can not be increased so much,
and the area of the diaphragm is reduced. The volume of the tweeter (high frequency band)
becomes small, and the frequency characteristic of the entire earphone becomes a high
frequency attenuated one.
[0032]
Hereinafter, the principle of the tweeter unit of the present invention will be described. Examples
1 to 5 show tweeter units.
[0033]
FIG. 2 is a view showing a configuration example of the tweeter unit. The configuration of the
tweeter unit 2 is shown in a perspective view in FIG. The tweeter unit 2 includes a diaphragm 21
and a housing 22, and the housing 22 is provided with a sound output hole 23 and an
adjustment hole 24.
[0034]
The diaphragm 21 is supported by the support portion 21 a, is attached with a piezoelectric
element (not shown), and vibrates based on a voltage applied to the piezoelectric element. The
configuration of the diaphragm and the piezoelectric element may be a unimorph type having a
piezoelectric element on one side of the diaphragm or a bimorph type having a piezoelectric
element on one side of the diaphragm.
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[0035]
The housing 22 is a square pole shaped pipe having a rectangular cross section.
[0036]
The sound release hole 23 is an outlet for compression waves (sounds) of air generated by
vibration.
The sound is emitted from the sound emission hole 23 in the direction of the black arrow in the
figure. The direction of the black arrow is referred to as the axial direction of the pillars of the
box-like housing 22 (hereinafter referred to as the “sound emitting axis direction”. Not exactly
the same as), but in the same direction.
[0037]
The adjustment holes 24 are for preventing a pressure difference between the front and back
sides of the diaphragm 21 generated by the vibration of the diaphragm 21.
[0038]
FIG. 2B is a cross-sectional view of the tweeter unit 2 (a cross-sectional view at a plane S
indicated by a dashed-dotted line in FIG. 2A).
The sound generated by the vibration of the diaphragm 21 is reflected by the reflecting member
25 which is one surface of the housing 22 (the surface on the left front side in FIG. 2A) as shown
by thin arrows in the figure, and may be further vibrated in some cases. It is reflected by the
plate 21 and emitted from the sound emission hole 23. The normal direction of the diaphragm
21 is inclined by θ with respect to the direction perpendicular to the sound emission axis of the
prior art.
[0039]
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The diaphragm 21 is inclined at an angle θ with respect to the direction perpendicular to the
sound introducing axis 26. The area of the diaphragm 21 is S1 and the area of the virtual
diaphragm 21x in the case of the prior art in the case of the prior art not inclined with respect to
the direction perpendicular to the sound introducing axis 26 (a cross section perpendicular to the
sound emitting axis of the housing 22 When the area) is S2, S1 / S2 = sin θ. If θ = 45 degrees,
then S1 / S2 = √2. If θ> 45 degrees, then S1 / S2> √2. The rate of increase of the area of the
diaphragm 21 with respect to the prior art can be evaluated by the value of S1 / S2.
[0040]
Here, the virtual diaphragm 21x can move in the lateral direction of the drawing. In the present
embodiment, since the case 22 has a columnar shape, the area S2 of the virtual diaphragm 21x
does not change even if it moves in the lateral direction of the drawing. However, when the case
is not columnar, the area S2 of the virtual diaphragm 21x changes, so the value of S1 / S2 also
changes, and the increase ratio of the area of the diaphragm 21 to the prior art is evaluated It
may not be easy to do. However, the position of the virtual diaphragm 21x (the cross section
perpendicular to the sound output axis of the housing 22) may be the position of the most part of
the sound output hole of the diaphragm 21. In order to transmit the sound to the ear, in the prior
art, the diaphragm is made as close as possible to the sound emission hole. In this embodiment, a
virtual diaphragm 21 x of the diaphragm 21 is extended in the forehead direction with the sound
output hole 23. Thereby, the area S2 of the virtual diaphragm 21x can be defined as the crosssectional area of the cross section perpendicular to the sound output axis of the housing 22 at
the position of the most part of the sound output hole of the diaphragm 21.
[0041]
As mentioned above, although only the tweeter unit 2 was demonstrated, a woofer can be
provided in addition and an earphone can be comprised. The present invention improves the
volume of the high frequency region (and the frequency characteristics based thereon), and the
principle of the improvement is due to the tweeter unit 2. Hereinafter, only the tweeter unit 2
will be described also in the second to fifth embodiments.
[0042]
As described above in detail, according to the tweeter unit of the present embodiment, the area of
the vibrating plate of the tweeter using the piezoelectric element can be increased, and the
volume of the high frequency region can be increased.
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[0043]
The present embodiment shows the arrangement of the diaphragm 21 and the reflector 25
different from the first embodiment.
Detailed descriptions of parts similar to those of the first embodiment will be omitted.
[0044]
FIG. 3 is a diagram showing a configuration example of the tweeter unit. The structure of the
tweeter unit 2 is shown by a perspective view in FIG. 3 (A). The tweeter unit 2 includes a
diaphragm 21 and a housing 22, and the housing 22 is provided with a sound output hole 23.
[0045]
Unlike the first embodiment, the adjustment hole 24 is not provided. Because the diaphragm 21
does not separate the space in the housing 22, it is not necessary to consider the air pressure on
the back side of the diaphragm 21.
[0046]
The diaphragm 21 is provided on the side surface of the housing 22. It is provided at a position
where θ = 90 degrees in the first embodiment. By designing the length of the housing 22 ("left
and right direction" in the figure), the value of S1 can be arbitrarily increased. That is, the value
of S1 / S2 can be arbitrarily increased.
[0047]
FIG. 3B is a cross-sectional view of the tweeter unit 2 (a cross-sectional view in a plane S
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indicated by a dashed-dotted line in FIG. 3A). The sound generated by the vibration of the
diaphragm 21 is reflected by the reflecting material 25 which is one surface of the housing 22
(the surface facing the diaphragm 21) as shown by the arrow in the figure, and in some cases, is
further reflected by the diaphragm 21. And emitted from the sound release hole 23.
[0048]
A diaphragm 21 is provided on the side of the housing 22, and sound is emitted perpendicularly
to the sound emission axis. For this reason, in order to direct the sound to the sound emission
hole 23, the reflector 25 which is one surface of the housing 22 is inclined by φ with respect to
the sound emission axis. In the first embodiment, φ = 90 degrees, but in the present
embodiment, φ <90 degrees.
[0049]
As described above in detail, according to the tweeter unit of this embodiment, the area of the
vibration plate of the tweeter using the piezoelectric element can be increased to an arbitrary
value according to the design, and the volume of the high frequency region is increased. It can be
enlarged.
[0050]
This embodiment is a combination of the arrangement of the diaphragm 21 and the reflector 25
in the first and second embodiments.
Detailed descriptions of parts similar to those in the first and second embodiments will be
omitted.
[0051]
FIG. 4 is a view showing a configuration example of the tweeter unit. FIG. 3 is a cross-sectional
view similar to that shown in FIG. 2 (B) and FIG. 3 (B). As shown in the first embodiment, the
diaphragm 21 is inclined by θ, and the reflecting material 25 is inclined by φ.
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[0052]
As shown in the figure, the fact that both the diaphragm 21 and the reflecting member 25 are
inclined has an effect of accurately directing the sound reflected by the reflecting member 25 in
the sound emission axis direction. If the normal direction of the surface of the reflector 25 is
equal to the direction of the bisector of the angle between the normal of the diaphragm 21 and
the sound emission axis, the reflected sound is accurately emitted in the direction of the sound
emission axis Ru. The relationship of φ = 90 degrees−θ / 2 may be established. In the figure,
θ = φ = 60 degrees.
[0053]
Also by setting θ = 45 degrees in the first embodiment and φ = 45 degrees in the second
embodiment, it is possible to correctly direct the sound reflected by the reflector 25 in the sound
emission axis direction. However, by tilting both of the diaphragm 21 and the reflector 25 as in
the present embodiment, the sound reflected by the reflector 25 can be accurately emitted in the
sound emission axis direction without making the diameter of the tweeter unit 2 too large. Can
be turned to
[0054]
As described above in detail, according to the tweeter unit of this embodiment, the sound
reflected by the reflector 25 can be accurately directed in the sound emission axis direction
without increasing the diameter of the tweeter unit 2 too much.
[0055]
In the present embodiment, the shape of the reflective material 25 in the second embodiment is
different.
Detailed descriptions of parts similar to those of the second embodiment will be omitted.
[0056]
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FIG. 5 is a view showing a configuration example of the tweeter unit. The structure of the tweeter
unit 2 is shown by a perspective view in FIG. 5 (A). Unlike the second embodiment, the reflector
25 has a curved shape.
[0057]
FIG. 5B shows a cross-sectional view of the tweeter unit 2 (a cross-sectional view in a plane S
indicated by a dashed-dotted line in FIG. 5A). The curved surface shape of the reflecting member
25 is a paraboloid of revolution having a focal point at a point 25F spaced apart from the center
position of the sound output hole 23 by a distance D along the sound emission axis and outside
the housing 22. The rotation axis passes through the focal point 25F and is a straight line in the
normal direction of the diaphragm 21 as indicated by P in the figure.
[0058]
The distance D may be a distance from the sound release hole 23 to the tympanic membrane.
However, if D ≧ 0, it may be designed arbitrarily.
[0059]
All sound emitted from the diaphragm 21 and reflected by the reflector 25 passes through the
focal point 25F. At the focal point 25F, the volume of the high frequency band is maximum.
[0060]
As described above in detail, according to the tweeter unit of this embodiment, the sound
reflected by the reflector 25 can be concentrated on the focal point 25F to increase the volume
of the high frequency band.
[0061]
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In the present embodiment, the shape of the housing 22 in the first embodiment is different.
Detailed descriptions of parts similar to those of the first embodiment will be omitted.
[0062]
FIG. 6 is a view showing a configuration example of the tweeter unit. The configuration of the
tweeter unit 2 is shown in a perspective view in FIG. Unlike the first embodiment, the housing 22
has a semicircular cross section.
[0063]
The diaphragm 21 has a hole 21b, and a MEMS element 21c (for example, a thin film of PZT thin
film formed on a silicon wafer and configured to apply a voltage with a platinum thin film) is
attached to cover the hole 21b. There is. The hole 21b is not completely covered by the MEMS
element 21c, and as shown in the figure, narrow gaps are formed on both sides of the MEMS
element 21c.
[0064]
Also in the first to fourth embodiments, the tweeter may be configured using the MEMS element
in this way instead of the piezoelectric element.
[0065]
As described above in detail, according to the tweeter unit of this embodiment, the same effect as
that of the tweeter unit of the first embodiment can be obtained by the tweeter unit 2 having the
casing 22 having a semicircular cross section.
The effect of making the cross-section semi-circular shape is shown in Example 8.
[0066]
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Hereinafter, an embodiment of the present invention will be described with reference to an
earphone. The earphone is also referred to as a housing ("ear plug") inserted into the ear. ), The
tweeter unit and the woofer unit. The tweeter unit uses the tweeter unit of the present invention
shown in Examples 1-5. As the woofer unit, a dynamic type, a balunstature type, or other widely
used one may be used.
[0067]
FIG. 7 is a view showing a configuration example of the earphone. The structure of the tweeter
unit 2 and the woofer unit 3 is shown by a perspective view to FIG. 7 (A). The tweeter unit 2 is as
shown in the first embodiment. The woofer unit 3 includes a woofer 31 (not shown) in a housing
32 and emits sound from the sound emission hole 33.
[0068]
The tweeter unit 2 uses a tweeter in which five piezoelectric sheets each having a thickness of 14
μm are laminated to a diaphragm 21 made of a titanium alloy of 5.9 mm × 4 mm × 0.05 mm.
The dimensions of the piezoelectric element are 5.5 mm × 3.8 mm × 0.075 mm.
[0069]
FIG. 8 is a diagram showing an example of the tweeter. The diaphragm 21 is supported by the
support portion 21a as shown in FIG. 8A, and is bent and vibrated by the vibration of the
piezoelectric element 21d. In addition, you may support like FIG. 8 (B) (C). The vibrating plate
and the piezoelectric element structure may be optionally designed as long as they generate
bending vibration. By the bending vibration, sound (compression wave of air) is radiated in the
normal direction of the diaphragm 21.
[0070]
The woofer unit 3 is of a balunstature type having an outer dimension of 5.6 mm × 4.3 mm ×
2.8 mm and a reproduction frequency band of 20 to 20000 Hz.
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[0071]
A cross-sectional view of the earphone 1 is shown in FIG. 7 (B).
The tweeter unit 2 and the woofer unit 3 are arranged in parallel along the sound introduction
axis (the left and right direction in the drawing). In order to reduce the diameter of the case 11 of
the earphone with this structure, it is preferable that the woofer unit 3 be a small-diameter
balunstature type.
[0072]
FIG. 9 is a diagram showing frequency characteristics. White noise was generated and the
frequency characteristics of the output sound were measured. In the figure, the solid line 41 is
that of the present embodiment, and the broken line 42 is that measured in the same manner as
in the prior art, with no signal input to the tweeter unit. The solid line 41 maintains the volume of
the high frequency band.
[0073]
As described above in detail, according to the earphone of the present embodiment, the area of
the diaphragm 21 can be increased, the volume of the high frequency band can be maintained,
and good frequency characteristics can be obtained.
[0074]
In the present embodiment, the tweeter unit 2 in the sixth embodiment is replaced with that
shown in the second embodiment.
Detailed descriptions of parts similar to those of the sixth embodiment will be omitted.
[0075]
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FIG. 10 is a view showing a configuration example of the earphone. The structure of the tweeter
unit 2 and the woofer unit 3 is shown by a perspective view to FIG. 10 (A). FIG. 10B shows a
cross-sectional view of the earphone 1. The tweeter unit 2 is the same as the sixth embodiment
except that the tweeter unit 2 is the one shown in the second embodiment.
[0076]
FIG. 11 is a diagram showing frequency characteristics. The frequency characteristics of the
output sound were measured. In the figure, the solid line 41 is that of the present embodiment,
and the broken line 42 is that in which the diaphragm of the tweeter unit 3 is perpendicular to
the sound output axis (in place of the diaphragm 21, the virtual diaphragm 21 x in FIG. ). The
volume of the high frequency band is maintained.
[0077]
As compared with the sixth embodiment, the volume of the high frequency band is kept larger.
The volume of the high frequency band is large despite the area of the diaphragm 21 being
smaller than that of the sixth embodiment, which is considered to be because the direction of the
reflected sound is close to the sound emission axis. In addition, it is conceivable to reduce the
influence of the air spring on the back side (the side without the piezoelectric element) of the
diaphragm 21.
[0078]
As described above in detail, according to the earphone of the present embodiment, the area of
the diaphragm 21 can be increased, and the volume of the high frequency band can be
maintained compared to the sixth embodiment, and a good frequency can be obtained.
Characteristics can be obtained.
[0079]
The present embodiment uses the tweeter unit 2 of the fifth embodiment, and the tweeter unit 2
and the woofer unit 3 are disposed at places different from the sixth and seventh embodiments.
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Detailed descriptions of parts similar to those in the sixth and seventh embodiments will be
omitted.
[0080]
FIG. 12 is a view showing a configuration example of an earphone. FIG. 12A shows the
configuration of the tweeter unit 2 and the woofer unit 3 in a sectional view. The tweeter unit 2
is that shown in the fifth embodiment. The woofer unit 3 is a dynamic type.
[0081]
The tweeter unit 2 has a semi-cylindrical shape with a diameter of 4.0 mm and a length of 5.0
mm. The MEMS element 21c is configured to form a 2 μm PZT thin film on a silicon wafer
having an outer dimension of 2.8 mm × 1.3 mm × 0.012 mm and apply a voltage with a
platinum thin film. The hole 21 b has a size of 2.5 mm × 1.6 mm. The width of the narrow gap
on both sides of the MEMS element 21c is 0.15 mm.
[0082]
The woofer unit 3 is a dynamic type with a diameter of 5.8 mm. In the present embodiment,
since the woofer unit 3 is not disposed in parallel with the tweeter unit 2 toward the sound
guiding axis, the diameter of the woofer unit 3 can be larger than in the sixth and seventh
embodiments. A dynamic type can be adopted.
[0083]
Since the tweeter unit 2 has a semi-cylindrical shape, it is accommodated in a half volume of the
ear plug portion 11 a of the housing 11 of the earphone. The other half can be the passage of
sound from the woofer unit 3.
[0084]
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FIG. 12B shows the earphone as viewed from the sound guiding axis (ear side). The treble is
emitted from the upper side of the figure and the bass is emitted from the lower side.
[0085]
FIG. 13 is a diagram showing frequency characteristics. White noise was generated and the
frequency characteristics of the output sound were measured. In the figure, the solid line 41
corresponds to that of this embodiment, and the broken line 42 corresponds to the diaphragm of
the tweeter unit 3 perpendicular to the sound output axis. As in the sixth and seventh
embodiments (strictly speaking somewhat strong), the volume of the high frequency band is
maintained. Also, by making the woofer unit a dynamic type, the volume of the low frequency
band is sufficient.
[0086]
As described above in detail, according to the earphone of the present embodiment, it is possible
to maintain the volume of the high frequency band and obtain excellent frequency characteristics
by using the dynamic woofer.
[0087]
It is a tweeter unit capable of obtaining a sound volume of a small diameter and a sufficiently
high frequency band, and an earphone using the tweeter unit.
It may be used by many earphone producers.
[0088]
DESCRIPTION OF SYMBOLS 1 earphone 11 housing | casing (earphone) 2 tweeter unit 21
diaphragm 21a support part 21b hole part 21c MEMS element 21d piezoelectric element 22
housing | casing (tweeter unit main body) 23 sound emission hole 24 adjustment hole 25
reflector 3 woofer unit 31 woofer 32 Housing (woofer unit) 33 Sound emission hole (woofer)
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