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JP2016086435

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DESCRIPTION JP2016086435
Abstract: The present invention provides an electro-acoustic transducer capable of improving
assemblability and easily obtaining desired frequency characteristics. An earphone (100)
includes a housing (41), a piezoelectric sounding body (32), an electromagnetic sounding body
(31), a passage portion (35), and wiring members (C1, C2, C3). The piezoelectric speaker 32
includes a first diaphragm 321 directly or indirectly supported by the housing 41, and a
piezoelectric element 322 disposed on at least one surface of the first diaphragm 321. The inside
of the body 41 is divided into a first space S1 and a second space S2. The electromagnetic
speaker 31 has a second diaphragm and is disposed in the first space S1. The passage portion 35
is provided around the piezoelectric sounding body 32 or the piezoelectric sounding body 32 to
communicate the first space portion S1 with the second space portion S2. The wiring member C3
is electrically connected to the piezoelectric element 322, and is drawn to the side of the
electromagnetic sounding body 31 via a gap between the circumferential surface of the
electromagnetic sounding body 31 and the side wall 412 of the housing 41. [Selected figure]
Figure 1
Electro-acoustic transducer
[0001]
The present invention relates to an electroacoustic transducer applicable to, for example,
earphones, headphones, portable information terminals, and the like.
[0002]
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The piezoelectric sounding element is widely used as a simple electroacoustic conversion means,
and is widely used as, for example, an acoustic device such as an earphone or a headphone, and
further as a speaker of a portable information terminal.
The piezoelectric sound emitting element typically has a configuration in which a piezoelectric
element is bonded to one side or both sides of a diaphragm (see, for example, Patent Document
1).
[0003]
On the other hand, Patent Document 2 describes a headphone including a dynamic driver and a
piezoelectric driver, and by driving these two drivers in parallel, reproduction with a wide
bandwidth is possible. The piezoelectric driver is provided at the center of the inner surface of a
front cover that closes the front surface of the dynamic driver and functions as a diaphragm, and
is configured to function as the high-range driver.
[0004]
Unexamined-Japanese-Patent No. 2013-150305 Unexamined-Japanese-Patent No. 62-68400
[0005]
In recent years, in audio equipment such as earphones and headphones, for example, further
improvement in assemblability and sound quality is required.
However, in the configuration of Patent Document 2, since the dynamic type driver is closed by
the front cover, there is a problem that sound waves can not be generated with desired frequency
characteristics. Specifically, it flexibly responds to adjustment of the peak level in a
predetermined frequency band, optimization of the frequency characteristic at the intersection
(cross point) of the characteristic curve of the bass region and the characteristic curve of the
treble region, etc. It is difficult.
[0006]
In view of the circumstances as described above, it is an object of the present invention to
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provide an electroacoustic transducer capable of easily obtaining desired frequency
characteristics while improving the assemblability.
[0007]
In order to achieve the above object, an electroacoustic transducer according to an aspect of the
present invention includes a housing, a piezoelectric speaker, an electromagnetic speaker, a
passage, and a wiring member.
The piezoelectric speaker includes a first diaphragm directly or indirectly supported by the
housing, and a piezoelectric element disposed on at least one surface of the first diaphragm. The
piezoelectric speaker divides the inside of the housing into a first space and a second space. The
electromagnetic speaker has a second diaphragm and is disposed in the first space. The passage
portion is provided around the piezoelectric sounding body or the piezoelectric sounding body,
and establishes communication between the first space portion and the second space portion.
The wiring member is electrically connected to the piezoelectric element, and is drawn to the side
of the electromagnetic sounding body through a gap between the circumferential surface portion
of the electromagnetic sounding body and the side wall portion of the housing.
[0008]
In the above-mentioned electroacoustic transducer, the sound wave generated by the
electromagnetic sounding body vibrates the first diaphragm of the piezoelectric sounding body to
propagate the sound wave component to the second space portion, and the second sound wave
portion through the passage portion. It is formed by the synthetic wave with the sound wave
component which propagates to the space part of. Therefore, by optimizing the size, number, and
the like of the passage portions, it becomes possible to adjust the sound wave output from the
piezoelectric speaker to a desired frequency characteristic. The electromagnetic speaker is
typically configured to produce sound waves in the lower frequency range than the piezoelectric
speaker. In this case, for example, it is possible to easily obtain a frequency characteristic such
that a sound pressure peak can be obtained in a predetermined bass band.
[0009]
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Further, since the passage portion is provided in the piezoelectric sounding body, the resonance
frequency of the first diaphragm (the frequency characteristic of the piezoelectric sounding
body) can be adjusted by the form of the passage portion. Thereby, for example, it is easy to
make desired frequency characteristics flat, for example, to flatten the synthetic frequency at the
crossing point (cross point) between the characteristic curve of the low tone range by the
electromagnetic speaker and the characteristic curve of the high tone range by the piezoelectric
speaker. Can be realized.
[0010]
Furthermore, the passage portion has a function as a low pass filter that cuts high frequency
components above a predetermined level among the sound waves generated from the
electromagnetic speaker. Thereby, it becomes possible to output a sound wave of a
predetermined low frequency band without affecting the frequency characteristic of the high
sound range generated by the piezoelectric speaker.
[0011]
And since the wiring member electrically connected to the piezoelectric element is configured to
be drawn out to the side of the electromagnetic sounding body through the gap between the
peripheral surface portion of the electromagnetic sounding body and the side wall portion of the
housing It is possible to assemble the piezoelectric sounding body to the housing without losing
the rigidity.
[0012]
As described above, according to the present invention, desired frequency characteristics can be
easily obtained while improving the assemblability.
[0013]
FIG. 1 is a schematic side sectional view showing an electro-acoustic transducer according to an
embodiment of the present invention.
It is a schematic sectional side view which shows the state before the assembly of the
electromagnetic type and piezoelectric type sounding body in the said electroacoustic transducer.
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It is a schematic plan view of the said electromagnetic type sounding body. It is a schematic
perspective view which shows one structural example of the piezoelectric element which
comprises the said piezoelectric type sounding body. It is a schematic sectional side view of the
piezoelectric element of FIG. It is a schematic perspective view which shows the other structural
example of the said piezoelectric element. It is a schematic sectional side view of the piezoelectric
element of FIG. It is a schematic plan view which shows one structural example of the said
piezoelectric type sounding body. It is a schematic plan view which shows the other structural
example of the said piezoelectric type sounding body. It is a figure which shows the frequency
characteristic of the electroacoustic transducer which concerns on a comparative example. It is a
figure which shows the frequency characteristic of the electroacoustic transducer of FIG. It is a
schematic sectional side view which shows the electroacoustic transducer which concerns on
other embodiment of this invention. It is a schematic plan view which shows one structural
example of the piezoelectric-type sounding body in the electroacoustic transducer of FIG. It is a
schematic plan view which shows the other structural example of the said piezoelectric type
sounding body. It is a schematic plan view which shows the other structural example of the said
piezoelectric type sounding body. It is a figure which shows the frequency characteristic of the
electroacoustic transducer of FIG. It is a schematic diagram which shows the modification of a
structure of the said electroacoustic transducer. It is a sectional view showing roughly the
internal structure of the above-mentioned electromagnetic sounding body. It is principal part
sectional drawing which shows the modification of a structure of the said electroacoustic
transducer. It is a schematic sectional side view which shows the electroacoustic transducer
which concerns on other embodiment of this invention.
[0014]
Hereinafter, embodiments according to the present invention will be described with reference to
the drawings.
[0015]
First Embodiment FIG. 1 is a schematic side sectional view showing a configuration of an
earphone 100 as an electroacoustic transducer according to an embodiment of the present
invention.
In the figure, the X-axis, the Y-axis and the Z-axis indicate three axis directions orthogonal to
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each other.
[0016]
[Overall Configuration of Earphone] The earphone 100 has an earphone body 10 and an earpiece
20. The earpiece 20 is attached to the sound path 11 of the earphone body 10 and configured to
be attachable to the user's ear.
[0017]
The earphone body 10 has a sound producing unit 30 and a housing 40 for housing the sound
producing unit 30. The sound production unit 30 has an electromagnetic sounding body 31 and
a piezoelectric sounding body 32. The housing 40 has a housing 41 and a cover 42.
[0018]
[Case] The case 41 has a cylindrical shape with a bottom, and is typically made of a plastic
injection molded body. The housing 41 has an internal space for accommodating the sound
generation unit 30, and the sound passage 11 communicating with the internal space is provided
at the bottom 410 thereof.
[0019]
The housing 41 has a support portion 411 supporting the peripheral portion of the piezoelectric
sounding body 32 and a side wall portion 412 surrounding the periphery of the sounding unit
30. The support portion 411 and the side wall portion 412 are both formed in an annular shape,
and the support portion 411 is provided so as to protrude inward from the vicinity of the bottom
portion of the side wall portion 412. The support portion 411 is formed as a plane parallel to the
XY plane, and supports the peripheral portion of the piezoelectric sounding body 32 described
later directly or indirectly via another member. In addition, the support part 411 may be
comprised by several columnar body cyclically arrange | positioned along the internal peripheral
surface of the side wall part 412. As shown in FIG.
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[0020]
[Electromagnetic Sounding Body] The electromagnetic sounding body 31 is composed of a
speaker unit that functions as a woofer that reproduces a low tone range. In the present
embodiment, for example, a dynamic speaker that mainly generates a sound wave of 7 kHz or
less, a mechanical unit 311 including a vibrating body such as a voice coil motor
(electromagnetic coil), and a pedestal unit 312 that vibratably supports the mechanical unit 311.
And. The pedestal portion 312 is formed in a substantially disk shape having an outer diameter
substantially the same as the inner diameter of the side wall portion 412 of the housing 41, and
has a circumferential surface portion 31e (FIG. 2) fitted to the side wall portion 412.
[0021]
The configuration of the mechanical portion 311 of the electromagnetic speaker 31 is not
particularly limited. FIG. 18 is a cross-sectional view of an essential part showing one
configuration example of the mechanical part 311. As shown in FIG. The mechanical section 311
has a diaphragm E1 (second diaphragm) vibratably supported by the pedestal portion 312, a
permanent magnet E2, a voice coil E3, and a yoke E4 supporting the permanent magnet E2. The
diaphragm E1 is supported by the pedestal portion 312 by the peripheral edge thereof being
sandwiched between the bottom portion of the pedestal portion 312 and the annular fixture 310
integrally assembled thereto.
[0022]
The voice coil E3 is formed by winding a conducting wire around a bobbin serving as a winding
core, and is joined to the central portion of the diaphragm E1. Further, the voice coil E3 is
disposed perpendicularly to the direction of the magnetic flux of the permanent magnet E2 (in
the Y-axis direction in the drawing). When an alternating current (voice signal) is supplied to the
voice coil E3, an electromagnetic force acts on the voice coil E3, so the voice coil E3 vibrates in
the Z-axis direction in the figure in accordance with the signal waveform. This vibration is
transmitted to the diaphragm E1 connected to the voice coil E3, and the air in the first space S1
is vibrated to generate a sound wave in the low frequency range.
[0023]
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FIG. 2 is a schematic side sectional view of the sound generation unit 30 showing a state before
assembling to the housing 41, and FIG. 3 is a schematic plan view of the sound generation unit
30. As shown in FIG.
[0024]
The electromagnetic speaker 31 has a disk shape having a first surface 31 a facing the
piezoelectric speaker 32 and a second surface 31 b on the opposite side.
At the periphery of the first surface 31 a, a leg 312 a is provided so as to be in contact with the
periphery of the piezoelectric sounding body 32. Although the leg part 312a is formed annularly,
it is not restricted to this and may be constituted by a plurality of columns.
[0025]
The second surface 31 b is formed on the surface of a disk-like raised portion 31 c provided at
the center of the upper surface of the pedestal portion 312. The circuit board 33 which
comprises the electric circuit of the sound generation unit 30 is being fixed to the 2nd surface
31b. As shown in FIG. 3, on the surface of the circuit board 33, a plurality of terminal portions
331, 332, 333 connected to various wiring members are provided. The circuit board 33 is
typically formed of a wiring board, but may be a board provided with terminal portions to which
at least each wiring member is connected. Further, the circuit board 33 is not limited to the
example provided on the second surface 31 b, and may be provided on another part such as the
inner wall of the cover 42, for example.
[0026]
The terminal portions 331 to 333 are provided in pairs. The terminal portion 331 is connected
with a wiring member C1 for inputting a reproduction signal transmitted from a reproduction
device (not shown). The terminal portions 332 are electrically connected to the terminal portions
313 of the electromagnetic sounding body 31 through the wiring member C2. The terminal
portion 333 is electrically connected to the terminal portions 324 and 325 of the piezoelectric
sounding body 32 through the wiring member C3. The wiring members C2 and C3 may be
directly connected to the wiring member C1 without the circuit board 33 interposed
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therebetween.
[0027]
[Piezoelectric Sounding Body] The piezoelectric sounding body 32 constitutes a speaker unit that
functions as a tweeter that reproduces a high range. In the present embodiment, the oscillation
frequency is set so as to mainly generate, for example, a sound wave of 7 kHz or more. The
piezoelectric speaker 32 includes a vibrating plate 321 (first vibrating plate) and a piezoelectric
element 322.
[0028]
The diaphragm 321 is made of a conductive material such as a metal (for example, 42 alloy) or
an insulating material such as a resin (for example, liquid crystal polymer), and the planar shape
thereof is substantially circular. The term "substantially circular" means not only circular but also
substantially circular as described later. The outer diameter and thickness of the diaphragm 321
are not particularly limited, and are appropriately set according to the size of the housing 41, the
frequency band of the reproduced sound wave, and the like. The outer diameter of the
diaphragm 321 is set smaller than the outer diameter of the electromagnetic speaker 31. In the
present embodiment, a diaphragm with a diameter of about 12 mm and a thickness of about 0.2
mm is used. The diaphragm 321 is not limited to a flat plate, and may be a three-dimensional
structure such as a dome shape.
[0029]
The diaphragm 321 may have a notch formed in a concave shape or a slit shape which is
recessed from the outer periphery toward the inner peripheral side, as necessary. In addition, if
the planar shape of the diaphragm 321 is a circle as a rough shape, even if it is not strictly a
circle due to the formation of the above-mentioned notches, it is regarded as a circle
substantially.
[0030]
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As shown in FIGS. 1 and 2, the diaphragm 321 has a peripheral portion 321 c supported by the
housing 41. The sound generation unit 30 further includes an annular member 34 disposed
between the support portion 411 of the housing 41 and the peripheral portion 321 c of the
diaphragm 321. The annular member 34 has a support surface 341 for supporting the leg 312 a
of the electromagnetic speaker 31. The outer diameter of the annular member 34 is formed
substantially the same as the inner diameter of the side wall portion 412 of the housing 41.
[0031]
In the peripheral portion 321 c of the diaphragm 321, the peripheral portion of one main surface
(first main surface 32 a) of the diaphragm 321 and the peripheral edge of the other main surface
(second main surface 32 b) of the diaphragm 321 And a side surface of the diaphragm 321.
[0032]
The material which comprises the cyclic member 34 is not specifically limited, For example, it is
comprised with elastic materials, such as a metal material, a synthetic resin material, rubber |
gum, etc.
When the annular member 34 is made of an elastic material such as rubber, the vibration of the
resonance of the diaphragm 321 is suppressed, whereby a stable resonance operation of the
diaphragm 321 can be secured.
[0033]
The diaphragm 321 has a first main surface 32 a facing the sound path 11 and a second main
surface 32 b facing the electromagnetic speaker 31. In the present embodiment, the piezoelectric
speaker 32 has a unimorph structure in which the piezoelectric element 322 is bonded only to
the second major surface 32 b of the diaphragm 321.
[0034]
Not limited to this, the piezoelectric element 322 may be joined to the first major surface 32 a of
the diaphragm 321. In addition, the piezoelectric speaker 32 may have a bimorph structure in
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which piezoelectric elements are respectively bonded to both main surfaces 32 a and 32 b of the
diaphragm 321.
[0035]
FIG. 4 is a schematic perspective view showing one configuration example of the piezoelectric
element 322, and FIG. 5 is a schematic cross-sectional view thereof. FIG. 6 is a schematic
perspective view showing another configuration example of the piezoelectric element 322, and
FIG. 7 is a schematic cross-sectional view thereof.
[0036]
The planar shape of the piezoelectric element 322 is formed in a polygonal shape, and in this
embodiment, it is rectangular (rectangular), but other quadrilaterals such as a square,
parallelogram, trapezoid, or a polygon other than a quadrilateral, or It may be circular, oval, oval
or the like. The thickness of the piezoelectric element 322 is also not particularly limited, and is,
for example, about 50 μm.
[0037]
The piezoelectric element 322 has a structure in which a plurality of piezoelectric layers and a
plurality of electrode layers are alternately stacked. Typically, the piezoelectric element 322
includes a plurality of ceramic sheets (dielectric layers) Ld having piezoelectric characteristics
such as lead zirconate titanate (PZT), an alkali metal-containing niobium oxide, etc. It is produced
by baking at predetermined temperature after laminating | stacking. One end portions of the
respective electrode layers are alternately drawn out to both end surfaces in the long side
direction of the dielectric layer Ld. The electrode layer Le exposed to one end face is connected
to the first lead-out electrode layer Le1, and the electrode layer Le exposed to the other end face
is connected to the second lead-out electrode layer Le2. The piezoelectric element 322 expands
and contracts at a predetermined frequency by applying a predetermined alternating voltage
between the first and second extraction electrode layers Le1 and Le2, and the diaphragm 321
vibrates at a predetermined frequency. The number of laminated layers of the piezoelectric layer
and the electrode layer is not particularly limited, and is set to an appropriate number of layers
that can obtain the required sound pressure.
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[0038]
In the configuration example of the piezoelectric element 322 shown in FIG. 4 and FIG. 5, the
first lead-out electrode layer Le1 is formed from one end face of the dielectric layer Ld to the
lower surface, and the second lead-out electrode layer Le2 is a dielectric layer It is formed from
the other end face of Ld to the upper surface. The lower surface of the piezoelectric element 322
is bonded to the second main surface 32b of the diaphragm 321 via a conductive material such
as solder or a conductive adhesive. In this case, the diaphragm 321 is made of a metal material,
but may be made of an insulating material in which the second major surface 32b is covered with
a conductive material.
[0039]
So, in this embodiment, as shown in FIG. 2, one wiring member C3 (1st wiring member) is
connected to the terminal part 324 provided in the diaphragm 321 among two wiring members
C3. The other wiring member C 3 (second wiring member) is connected to a terminal portion
325 provided on the piezoelectric element 322. One terminal portion 324 is provided on the
second main surface 32 b of the diaphragm 321, and the other terminal portion 325 is provided
on the second lead-out electrode layer Le 2 on the top surface of the piezoelectric element 322.
This makes it possible to apply a predetermined drive voltage between the first and second
extraction electrode layers Le1 and Le2.
[0040]
On the other hand, in the configuration example of the piezoelectric element 322 shown in FIG. 6
and FIG. 7, the first lead electrode layer Le1 is formed from one end face of the dielectric layer Ld
to a part of the top surface. Is formed from the other end face of the dielectric layer Ld to
another part of the top surface. In this case, since the two lead-out electrode layers Le1 and Le2
are exposed adjacent to each other on the upper surface of the piezoelectric element 322, the
terminal portions 324 and 325 may be provided on these. In this case, the diaphragm 321 may
be made of an insulating material.
[0041]
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As shown in FIG. 1, the piezoelectric sounding body 32 is assembled to the support portion 411
of the housing 41 in a state where the annular member 34 is mounted on the peripheral portion
321 c of the diaphragm 321. An adhesive layer may be provided between the annular member
34 and the support portion 411 to bond them. The internal space of the housing 41 is divided by
the piezoelectric speaker 32 into a first space portion S1 and a second space portion S2. The first
space portion S1 is a space portion that accommodates the electromagnetic sounding body 31,
and is formed between the electromagnetic sounding body 31 and the piezoelectric sounding
body 32. The second space S 2 is a space communicating with the sound path 11 and is formed
between the piezoelectric speaker 32 and the bottom of the housing 41.
[0042]
The electromagnetic speaker 31 is assembled on the annular member 34. An adhesive layer is
provided between the outer peripheral edge of the electromagnetic speaker 31 and the side wall
412 of the housing 41 as necessary. The adhesive layer also functions as a sealing layer, so that
the degree of sealing of the sound field formation space (first space portion S1) of the
electromagnetic sounding body 31 can be increased. In addition, the close contact between the
electromagnetic sounding body 31 and the annular member 34 makes it possible to stably
secure a predetermined volume of the first space S1 and to prevent the occurrence of sound
quality variation among products due to the fluctuation of the volume. can do.
[0043]
[Cover] The cover 42 is fixed to the upper end of the side wall portion 412 so as to close the
inside of the housing 41. A pressing portion 421 for pressing the electromagnetic sounding body
31 toward the annular member 34 is provided on the inner upper surface of the cover 42. Thus,
the annular member 34 is firmly held between the leg portion 312 a of the electromagnetic
sounding body 31 and the support portion 411 of the housing 41, so the peripheral portion 321
c of the diaphragm 321 is integrated with the housing 41. It is possible to connect to
[0044]
The pressing portion 421 of the cover 42 is formed in an annular shape, and the tip end portion
thereof is an annular upper surface portion 31 d formed around the raised portion 31 c of the
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electromagnetic sounding body 31 via the elastic layer 422 (FIG. 2 and FIG. 3). Contact). As a
result, the electromagnetic sounding body 31 is pressed with uniform force over the entire
circumference of the annular member 34, and the sounding unit 30 can be properly positioned
inside the housing 41. The pressing portion 421 is not limited to being formed annularly, and
may be configured by a plurality of columns.
[0045]
At a predetermined position of the cover 42, a feedthrough for leading the wiring member C1
connected to the terminal portion 331 of the circuit board 33 to a reproduction device (not
shown) is provided.
[0046]
[Drawing-Out Structure of Wiring Member C3] In the present embodiment, each wiring member
C3 connected to the piezoelectric sounding body 32 is configured to be drawn from the side of
the second main surface 32b of the diaphragm 321.
That is, since the terminal portions 324 and 325 of the piezoelectric sounding body 32 are
disposed to face the first space portion S1, there is a routing path for guiding the wiring member
C3 to the terminal portion 333 on the circuit board 33. It will be necessary. So, in this
embodiment, the guide groove which can accommodate wiring member C3 is provided in the
side peripheral surface of pedestal part 312 of electromagnetic sounding body 31, and annular
member 34, respectively, and wiring member C3 is a piezoelectric type. It is configured to be
drawn out from the sounding body 32 to the side of the electromagnetic sounding body 31 via
the first space portion S1.
[0047]
As shown in FIG. 2, the circumferential surface portion 31 e and the upper surface portion 31 d
of the electromagnetic sounding body 31 accommodate a plurality of wiring members C 3 routed
between the first surface 31 a and the second surface 31 b. A first guide groove 31f is provided.
Thus, the wiring member C3 is provided between the circumferential surface 31e of the
electromagnetic sounding body 31 and the side wall 412 of the housing 41 and between the
upper surface 31d of the electromagnetic sounding body 31 and the pressing portion 421 of the
cover 42. It can be easily pulled around without damaging it.
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[0048]
The first guide groove 31 f is formed along the radial direction in the upper surface portion 31 d
and along the height direction (Z-axis direction) in the circumferential surface portion 31 e. The
guide grooves 31f formed in the upper surface portion 31d and the circumferential surface
portion 31e are connected to each other. The first guide groove 31 f is configured by a square
groove, but may be configured by a concave groove of another shape such as a round groove.
Although the formation position of the first guide groove 31 f is not particularly limited, it is
preferable that the first guide groove 31 f be provided at a position near the terminal portion
333 of the circuit board 33 as shown in FIG. 3.
[0049]
In the case where the pressing portion 421 of the cover 42 is constituted by a plurality of
columns, the wiring member C3 can be passed between the columns, and hence the formation of
the guide groove 31f in the upper surface portion 31d is omitted. Can.
[0050]
On the other hand, the support surface 341 of the annular member 34 is provided with a second
guide groove 34a capable of accommodating the plurality of wiring members C3.
The second guide groove 34 a is formed linearly in the radial direction so as to connect between
the inner peripheral edge and the outer peripheral edge of the annular member 34. The second
guide groove 34 a is formed at a position in communication with the first guide groove 31 f in a
state where the sound generation unit 30 is incorporated in the housing 41. This makes it
possible to easily route the wiring member C3 between the leg portion 312a of the
electromagnetic speaker 31 and the annular member 34 without damaging the wiring member
C3. As described above, according to the present embodiment, the electromagnetic speaker 31
can be assembled to the housing 41 without impairing the workability.
[0051]
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[Passage] If the first space S1 is sealed, it may not be possible to generate sound waves in the low
frequency range with desired frequency characteristics. Specifically, it flexibly responds to
adjustment of the peak level in a predetermined frequency band, optimization of the frequency
characteristic at the intersection (cross point) of the characteristic curve of the bass region and
the characteristic curve of the treble region, etc. It becomes difficult.
[0052]
Therefore, in the present embodiment, the piezoelectric sounding body 32 is provided with the
passage portion 35 for communicating the first space portion S1 with the second space portion
S2. FIG. 8 is a schematic plan view showing the configuration of the piezoelectric speaker 32. As
shown in FIG.
[0053]
The passage portion 35 is provided in the thickness direction of the diaphragm 321. In the
present embodiment, the passage portion 35 is configured by a plurality of through holes
provided in the diaphragm 321. As shown in FIG. 8, a plurality of passage portions 35 are formed
around the piezoelectric element 322. Since the annular member 34 is attached to the peripheral
edge portion 321 e of the diaphragm 321, the passage portion 35 is provided in the region
between the piezoelectric element 322 and the annular member 34. In the present embodiment,
since the piezoelectric element 322 has a rectangular planar shape, the passage portion 35 is in
the region between at least one side of the piezoelectric element 322 and the peripheral portion
321 c (annular member 34) of the diaphragm 321. By being provided, the area | region which
forms the channel | path part 35 can be ensured, without restrict | limiting the magnitude | size
of the piezoelectric element 322 more than necessary.
[0054]
The passage portion 35 is for passing a part of the sound wave generated by the electromagnetic
sounding body 31 from the first space portion S1 to the second space portion S2. Therefore, the
frequency characteristics of the bass region can be adjusted or tuned depending on the number
and size of the passage portions 35, and the number and size of the passage portions 35 are
determined according to the frequency characteristics of the desired bass region. Ru. For this
reason, the number and the size of the passage portions 35 are not limited to the example of FIG.
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8 and, for example, the passage portions 35 may be singular.
[0055]
The opening shape of the passage portion 35 is not limited to a circle, and the number may be
different depending on the place. For example, the passage 35 may include an oval passage 351
as shown in FIG.
[0056]
[Operation of Earphone] Subsequently, a typical operation of the earphone 100 of the present
embodiment configured as described above will be described.
[0057]
In the earphone 100 of the present embodiment, the reproduction signal is input to the circuit
board 33 of the sound generation unit 30 via the wiring member C1.
The reproduction signal is input to the electromagnetic sounding body 31 and the piezoelectric
sounding body 32 through the circuit board 33 and the wiring members C2 and C3. As a result,
the electromagnetic sounding body 31 is driven to generate a sound wave mainly in the low
frequency range of 7 kHz or less. On the other hand, in the piezoelectric speaker 32, the
diaphragm 321 vibrates by the expansion and contraction of the piezoelectric element 322, and
a sound wave in a high temperature range of 7 kHz or more is mainly generated. The generated
sound waves in each band are transmitted to the user's ear via the sound path 11. Thus, the
earphone 100 functions as a hybrid speaker having a sound producing body for the low
frequency band and a sound producing body for the high frequency band.
[0058]
Here, a sound wave generated by the electromagnetic sounding body 31 vibrates the diaphragm
321 of the piezoelectric sounding body 32 and propagates to the second space portion S 2, a
sound wave component, and the second space via the passage portion 35. It is formed by a
synthetic wave with the sound wave component propagating to the part S2. Therefore, by
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optimizing the size, the number, and the like of the passage portions 35, the sound wave in the
low sound range output from the piezoelectric sounding body 32 has a frequency characteristic
such that a sound pressure peak can be obtained in a predetermined low sound band, for
example. It is possible to adjust or tune.
[0059]
In the present embodiment, since the passage portion 35 is constituted by the through hole
penetrating in the thickness direction of the diaphragm 321, the sound wave propagation path
from the first space portion S1 to the second space portion S2 is minimum (shortest) Can be This
makes it easy to set the sound pressure peak in a predetermined bass range.
[0060]
For example, FIG. 10 is a characteristic diagram of the reproduced sound wave when the sound
wave propagation path becomes longer than necessary. In the figure, the horizontal axis
represents frequency, and the vertical axis represents sound pressure (arbitrary unit), F1
represents the frequency characteristic of the bass range reproduced by the electromagnetic
speaker, and F2 represents the high range reproduced by the piezoelectric speaker. The
frequency characteristics are shown respectively. In the example of FIG. 10, a large dip occurs at
about 3 kHz. When the reproduced sound is music, the 3 kHz band generally corresponds to the
frequency band of vocal vocal sounds. Therefore, if a dip occurs in this band, the sound quality of
the vocal tends to be degraded.
[0061]
On the other hand, FIG. 11 is the same characteristic diagram as FIG. 10 about the reproduction |
regeneration sound wave when the passage part 35 is comprised by the shortest path. According
to this embodiment, a bass frequency characteristic having a peak near 3 kHz can be obtained.
As a result, the sound quality of the vocals is improved, and the reproduction quality of the music
can be improved.
[0062]
11-05-2019
18
In addition, the passage portion 35 has a function as a low pass filter that cuts high frequency
components above a predetermined level among the sound waves generated from the
electromagnetic speaker. As a result, it is possible to output a sound wave of a predetermined low
frequency band without affecting the frequency characteristic of the high sound range generated
by the piezoelectric speaker 32.
[0063]
Furthermore, according to the present embodiment, the piezoelectric sounding body 32 is
configured to draw out all of the plurality of wiring members C3 toward the second main surface
32b of the diaphragm 321. As compared with the case where the wiring is drawn out from the
main surface 32 a side, not only the connection workability of the wiring member C 3 to the
piezoelectric element 322 but also the assemblability to the housing 41 can be improved.
[0064]
Moreover, since the sound producing unit 30 can be collectively incorporated into the inside of
the housing 41 in a state where the electromagnetic sound producing body 31 and the
piezoelectric sound producing body 32 are mutually connected by the wiring member C3, the
assemblability is further enhanced. It can improve.
In addition, since the first and second guide grooves 31f and 34a capable of accommodating the
wiring member C3 are respectively provided on the peripheral surface 31e of the
electromagnetic sounding body 31 and the support surface 341 of the annular member 34, the
wiring member C3 can be used. It is possible to take a proper route without damaging it. As a
result, stable assembly accuracy can be secured without requiring the level of skill of operation.
[0065]
Second Embodiment FIG. 12 is a schematic cross-sectional view of an earphone 200 according to
another embodiment of the present invention. Hereinafter, configurations different from the first
embodiment will be mainly described, and the same configurations as those of the abovedescribed embodiment are denoted by the same reference numerals, and the description thereof
will be omitted or simplified.
11-05-2019
19
[0066]
The earphone 200 of the present embodiment is different from the above-described first
embodiment in the configuration of the sound generation unit 50, particularly the piezoelectric
sound generator 52. The piezoelectric speaker 52 has a vibration plate 521 and a piezoelectric
element 322 joined to one of the main surfaces of the vibration plate 521 (in the present
example, the main surface facing the first space S1).
[0067]
FIG. 13 is a schematic plan view showing the configuration of the piezoelectric speaker 52. As
shown in FIG. As shown in FIG. 13, a plurality of (three in the illustrated example) protruding
pieces 521 g are provided on the peripheral edge portion of the diaphragm 521 so as to radially
project radially outward. The plurality of projecting pieces 521 g are fixed to the inner
circumferential portion of the annular member 34. Therefore, the diaphragm 521 is fixed to the
support portion 411 of the housing 41 via the plurality of projecting pieces 521 g and the
annular member 34.
[0068]
The plurality of projecting pieces 521g are typically formed at equal angular intervals. The
plurality of projecting pieces 521 g are formed by providing a plurality of cutouts 521 h in the
peripheral portion of the diaphragm 521. The protrusion amount of the protrusion piece 521g is
adjusted by the notch depth of the notch part 521h.
[0069]
The piezoelectric sounding body 52 is provided with a passage 55 for communicating the first
space S1 with the second space S2. In the present embodiment, the notch depth of each notch
521 h is formed so that an arc-shaped opening having a predetermined width is formed between
the inner circumferential surface of the annular member 34 and the plurality of adjacent
projecting pieces 521 g. Is set. A passage portion 55 penetrating in the thickness direction of the
diaphragm 521 is formed by the opening.
11-05-2019
20
[0070]
The number of passage portions 55, the opening width along the radial direction of the
diaphragm 521, the opening length along the circumferential direction of the diaphragm 521,
and the like can be set as appropriate, and according to the frequency characteristics of the
desired bass range. It is determined. As a result, as in the first embodiment, for example, it is
possible to obtain the frequency characteristic of the reproduced sound having a sound pressure
peak in a predetermined low-pitch range (for example, 3 kHz). FIG. 14 shows a configuration
example of the diaphragm 521 having four projecting pieces 521g, and FIG. 15 shows a
configuration example of the diaphragm 521 having five projecting pieces 521g.
[0071]
Further, since the diaphragm 521 of the present embodiment is configured to vibrate with a part
or all of the plurality of projecting pieces 521g as a fulcrum, the resonance of the diaphragm 521
is caused by the number, shape, arrangement or fixing method of the projecting pieces 521g. It is
possible to adjust the frequency. For example, when the resonance frequency of the diaphragm
521 having four fulcrums as shown in FIG. 14 is designed to be 10 kHz, the resonance frequency
of the diaphragm 521 having three fulcrums as shown in FIG. The resonance frequency of the
diaphragm 521 having five fulcrums as shown in FIG. 15 is as high as 12 kHz, for example. In
addition, the resonance frequency can be adjusted also by the thickness, outer diameter, material
and the like of the diaphragm 521.
[0072]
As described above, since it is possible to adjust the resonance frequency of the diaphragm 521
by the number of the projecting pieces 521g and the like, for example, the characteristic curve of
the bass region by the electromagnetic speaker 31 and the high tone region by the piezoelectric
speaker 52. Desired frequency characteristics can be easily realized, for example, by flattening
the synthesized frequency at the intersection (cross point) with the characteristic curve.
[0073]
16A to 16C are schematic diagrams for explaining the relationship between the resonant
11-05-2019
21
frequency of the diaphragm 521 and the frequency characteristics of the reproduced sound of
the earphone 200. The horizontal axis represents frequency, and the vertical axis represents
sound pressure.
In each figure, F1 (thin solid line) indicates the bass range and frequency characteristics
reproduced by the electromagnetic sounding body 31, F2 (dotted line) indicates the frequency
characteristic of the high tone range reproduced by the piezoelectric sounding body 52, F0 (thick
solid line) indicates each of these combined characteristics. Furthermore, P indicates the
intersection point of the curve F1 and the curve F2, that is, the above-mentioned cross point.
[0074]
In FIGS. 16A to 16C, the resonance frequency of the diaphragm 521 increases in the order of B,
C, and A. In the example of FIG. 16A, dips easily occur in the band of the cross point P, and in the
example of FIG. 16B, peaks easily occur in the band of the cross point P. On the other hand, in
the example of FIG. 16C, flat characteristics are obtained in the band of the cross point P.
[0075]
In general, in a hybrid speaker, a cross point between a characteristic curve of a bass region and
a characteristic curve of a treble region is important in the tuning of sound quality. Typically, as
shown in FIG. 16C, the combined frequency of the low range and the high range is adjusted to be
flat in the band of the cross point P. According to the present embodiment, since the resonance
frequency of the diaphragm 521 can be adjusted by the number of supporting points (projecting
pieces 521g) of the diaphragm 521, desired frequency characteristics such that the band of the
cross point P becomes flat can be obtained. It can be easily realized.
[0076]
Third Embodiment FIG. 20 is a schematic cross-sectional view of an earphone 400 according to
another embodiment of the present invention. Hereinafter, configurations different from the first
embodiment will be mainly described, and the same configurations as those of the abovedescribed embodiment are denoted by the same reference numerals, and the description thereof
will be omitted or simplified.
11-05-2019
22
[0077]
The earphone 400 of the present embodiment is different from the first embodiment in the
configuration of the sound generation unit 70, in particular, the piezoelectric sound generator
72. The sound generation unit 70 includes an electromagnetic sound generator 31 and a
piezoelectric sound generator 72. The piezoelectric speaker 72 is configured in the same manner
as the piezoelectric speaker 32 of the first embodiment, but differs in that the piezoelectric
element 322 is joined to the second major surface 32 a of the diaphragm 321. The sound
generation unit 70 further includes an annular member 54 disposed between the support portion
411 of the housing 41 and the peripheral portion 321 c of the diaphragm 321.
[0078]
The annular member 54 has a contact surface 413 in contact with the support portion 411, and
a second guide groove 35a which is provided on the contact surface 413, communicates with the
first guide groove 31f, and accommodates the wiring member C3. The contact surface 413
includes the outer peripheral surface and the bottom surface of the annular member 54. The
second guide groove 35a is formed along the outer peripheral surface and the bottom surface of
the annular member 54, and in the outer peripheral surface, in the height direction (Z-axis
direction), in the bottom surface, along the radial direction. It is formed linearly. The second
guide groove 35a can accommodate a plurality of wiring members C3 in the same manner as the
first guide groove 31f.
[0079]
The wiring member C3 is electrically connected to the piezoelectric element 322, and is drawn
from the piezoelectric element 322 to the side of the electromagnetic sounding body 31 via the
second space portion S2. That is, the terminal portions 324 and 325 of the piezoelectric speaker
72 are disposed facing the second space S2, and the wiring member C3 connected to the
terminal portions 324 and 325 has the second guide groove 35a and the second guide groove
35a. It is led to the terminal portion 333 on the circuit board 33 through the first guide groove
31 f. According to the present embodiment, since the second guide groove 35a faces the second
space portion S2 and there is no guide groove facing the first space portion S1, the sealability of
the first space portion S1 is improved. To rise. Thereby, the leak of the sound pressure of the
11-05-2019
23
electromagnetic sounding body 31 is prevented, and it becomes easy to control the sound
pressure of the bass range. Further, for example, the vibration of the wiring caused by the sound
pressure leakage from the guide groove and the interference with the wiring may become a noise
source in the audible range as chattering noise (noise, noise). Since each wiring member C3 is on
the opposite side of the piezoelectric sounding body 72 from the electromagnetic sounding body
31, generation of such chattering noise can be prevented.
[0080]
Further, since the sound producing unit 70 can be collectively incorporated into the inside of the
housing 41 in a state where the electromagnetic sound producing body 31 and the piezoelectric
sound producing body 72 are mutually connected by the wiring member C3, the assemblability is
improved. Can be Further, since the first and second guide grooves 31f and 35a capable of
accommodating the wiring member C3 are respectively provided on the peripheral surface 31e
of the electromagnetic sounding body 31 and the contact surface 413 of the annular member 34,
the wiring member C3 can be used. It is possible to take a proper route without damaging it. As a
result, stable assembly accuracy can be secured without requiring the level of skill of operation.
[0081]
In the present embodiment, the piezoelectric element 322 is bonded to the second major surface
32 a of the diaphragm 321, but may be bonded to the first major surface 32 b. In this case, each
wiring member C3 may be drawn out from the side of the first main surface 32b, and may be
accommodated in the second guide groove 35a through the passage portion 35. That is, the
wiring member C3 is drawn out from the piezoelectric element 322 to the side of the
electromagnetic speaker through the first space S1. Such a configuration can also be applied to
the above embodiments.
[0082]
As mentioned above, although embodiment of this invention was described, this invention is not
limited only to the above-mentioned embodiment, of course, a various change can be added.
[0083]
11-05-2019
24
For example, in the above embodiments, the passage section for guiding the sound wave in the
low frequency range to the sound path is provided in the piezoelectric sounding body, but the
invention is not limited thereto, and may be provided around the piezoelectric sounding body.
In this case, for example, as schematically shown in FIG. 17, the outer diameter of the
piezoelectric sounding body U2 is smaller than the inner diameter of the side wall of the housing
B, and the electromagnetic sounding body U1 is generated between them. A passage portion T is
formed to pass the sound waves in the low frequency range. The piezoelectric speaker U2 is fixed
to the bottom B1 of the housing B via a plurality of columns R. Thereby, the sound wave which
passed passage part T can be led to sound path B2.
[0084]
Moreover, in the above embodiment, although the earphones 100, 200, and 300 have been
described as an example of the electroacoustic transducer, the present invention is not limited to
this, and can be applied to headphones, a hearing aid, and the like. The present invention can
also be applied as a speaker unit mounted in an electronic device such as a portable information
terminal or a personal computer.
[0085]
Furthermore, in each of the above embodiments, the sounding units 30, 50, 70 are configured as
separate parts of the electromagnetic sounding body 31 and the piezoelectric sounding body 32
(52, 72), respectively. It may consist of one part. For example, FIG. 19 shows a configuration
example of a sounding unit 300 in which the electromagnetic sounding body 31 and the
piezoelectric sounding body 32 are integrated.
[0086]
In FIG. 19, the peripheral edge portion 323 c of the diaphragm 323 of the piezoelectric speaker
32 is fixed to the pedestal 312 together with the peripheral edge of the diaphragm E 1 of the
electromagnetic speaker 31 by the annular fixture 310. The annular fixing tool 310 is assembled
to the pedestal portion 312 to form a fixing portion that commonly supports the peripheral
portions of the two diaphragms 323 and E1. Further, in the vibrating plate 323 of the
11-05-2019
25
piezoelectric sounding body 32, the central region joined to the piezoelectric element 322 and
constituting the vibrating surface is formed to be bent from the peripheral portion 323c in a
direction away from the vibrating plate E1 of the electromagnetic sounding body 31. It has a
shallow dish shape. This enables the two diaphragms 323 and E1 to vibrate independently
without interfering with each other.
[0087]
Further, in the central region of the diaphragm 323, there is provided a passage portion 35
through which sound waves of a low frequency range generated in the electromagnetic sounding
body 31 can pass. The passage portion 35 is configured by a through hole as in the first
embodiment, but may be configured by forming a notch in the peripheral portion 323 c as in the
second embodiment.
[0088]
According to the sounding unit 300 of the above configuration, since the electromagnetic
sounding body 31 and the piezoelectric sounding body 32 are formed as a single component
integrated with each other, the structure of the sounding unit 300 can be simplified and thinned.
It is possible to Further, since the number of parts can be reduced, the assemblability of the
electroacoustic transducer can be improved.
[0089]
DESCRIPTION OF SYMBOLS 10 ... Earphone main body 11 ... Sound path 20 ... Earpiece 30, 50,
70, 300 ... Sounding unit 31 ... Electromagnetic sounding body 32, 52, 72 ... Piezoelectric
sounding body 34, 54 ... Annular member 35, 55 ... Passage part 41 ... housing 321, 323, 521 ...
diaphragm 322 ... piezoelectric element S1 ... first space portion S2 ... second space portion
11-05-2019
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